Abstract:
The present invention relates to a method for evaluating the regenerative and/or differentiation capacity of ciliated epithelial tissue in a vertebrate subject, in particular a mammal, preferably a human, and to the use of microRNA in treating illnesses associated with a dysfunction of multiciliated epithelial cells.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the area of the regeneration and differentiation of ciliated epithelia in vertebrates, notably mammals, and in particular humans, leading to a functional ciliogenesis and to involvement of microRNAs in the process of regeneration and differentiation of said epithelia as well as to the genes modulated by said microRNAs. 
     The present invention relates more particularly to the use of microRNA in the treatment of diseases associated with a dysfunction of the cilia of multiciliated epithelial cells, especially disorders resulting from nonfunctional ciliogenesis, such as chronic respiratory diseases for which regeneration and/or differentiation of the airway epithelium is defective. 
     BACKGROUND OF THE INVENTION 
     The ciliated cells coating the apical surface of the epithelia are essential for various physiological processes such as cleaning of the respiratory passages, embryo implantation, or circulation of the cerebrospinal fluid. Defective ciliogenesis is the direct cause of or is associated with a great variety of diseases. 
     The process of ciliogenesis comprises a sequence of events that begins with acquisition of the identity of the ciliated cell (phase 1). This first step consists of lateral inhibition between two adjacent cells by the Notch signalling system via interaction between Notch and its ligand such as delta-like 1 (DLL1). The cell expressing the DLL1 ligand becomes a progenitor cell of ciliated cells, and simultaneously, activation of Notch in the neighbouring cells prevents transformation of these cells into progenitor cells of ciliated cells. The inventors have shown that the progenitor cell of ciliated cells expresses the microRNAs of the family miR-449 and the transcription factor FOXJ1. During a second phase, the miR-449s inhibit cell division and induce differentiation. Multiplication of the centrioles begins in the progenitor cell of ciliated cells, and this multiplication is followed by anchoring of the basal bodies to the apical pole of the cells; this step is followed by assembly of the axoneme and cilia synthesis proper. 
     The epithelia perform a barrier function between the internal medium and the external environment. The respiratory passages are coated with a highly differentiated pseudostratified epithelium consisting of mucus-secreting and ciliated basal cells (each ciliated cell having hundreds of cilia). The coordinated movement of these numerous cilia present on the surface of the epithelium permits the removal of waste carried by the mucus during a process called mucociliary clearance. In this connection, the cilia play an important role in the processes of defense against first-line respiratory tract infections (Puchelle et al.  Proc Am Thorac Soc  (2006) 3, 726-733). 
     The permanent exposure of the airway epithelium to environmental stresses caused by pathogenic microorganisms, allergens, toxic molecules, etc. leads to tissue lesions. Following these lesions, a physiological process of regeneration of the airway epithelium goes into action. This process, when successful, repairs the lesion and restores the integrity of the respiratory tissue, the lesion being replaced with tissue that is differentiated and is functional again. 
     This regeneration comprises several steps: 
     1) the epithelial cells proliferate and/or migrate in order to fill the wound bed; 
     2) these first steps are followed by activation of a step of cellular polarization characterized by the formation of tight junctions and by specific differential addressing of membrane proteins (channels, ion transporters etc.) between the apical pole and the basolateral pole (Puchelle et al. 2006; Hajj, R. et al.  J Pathol  (2007) 211, 340-350); 
     3) a stage of terminal differentiation leading to the formation of cilia on the surface of the ciliated cells (ciliogenesis) and to the presence of secretory cells responsible for the synthesis and secretion of mucus. 
     A pseudostratified mucociliary epithelium thus replaces the lesion, reconstituting a functional ciliated tissue having properties identical to those of the original tissue. 
     Taken together, these biological phenomena are associated with mechanisms of signal transduction and with particular gene expression profiles. Among certain known actors implicated in the differentiation and ciliogenesis of the airway epithelium, the Foxj1 transcription factor is one of the best documented (Yu, X. et al. (2008)  Nat Genet.  40, 1445-1453). Foxj1 acts in a late phase of ciliogenesis, playing a role in anchoring of the basal bodies (small organelles of structural organization close to the centrioles that are indispensable for formation of the base of the cilia) to the apical membrane during formation of the axoneme (Gomperts, B. N. et al. (2004)  J Cell Sci  117, 1329-1337 (2004). 
     In certain chronic respiratory diseases such as chronic obstructive pulmonary disease (COPD), mucoviscidosis, asthma or primary ciliary dyskinesia (PCD), inflammations and chronic infections lead to destruction of the respiratory tissue (Marshall, W. F. (2008)  J Cell Biol  180, 17-21). For reasons that are still poorly understood, these diseases are associated with defects of epithelial regeneration and differentiation. These defects result in abnormal restructuring of the tissue, fibrosis and irreversible functional loss (Marshall, W. F., 2008). There is still no therapeutic treatment for these various diseases, and only symptomatic treatments are available for combating, with a varying degree of effectiveness, the progressive destruction of the respiratory tissue. In this connection, elucidation of the mechanisms leading to the formation of functional cilia (ciliogenesis) represents a major challenge with obvious therapeutic benefits. 
     Cellular differentiation involves fine temporal and spatial regulation of the transcription and translation governing the expression of specific genes. These events are controlled by various molecular and mechanical signals. Understanding the physiological mechanisms underlying differentiation and ciliogenesis is therefore an indispensable prelude to the development of therapeutic approaches that are more specific and more effective. 
     The microRNAs (miRNAs), small noncoding RNAs of about 22 bases discovered in 1993, which have regulatory properties, play a key role in the regulation of cellular phenomena such as survival, apoptosis, proliferation, homeostasis or differentiation (Lu, Y. et al. (2007)  Dev Biol  310, 442-453). 
     Their mechanisms of action involve the formation of a complex between several bases of the miRNA and the noncoding 3′ portion of the target mRNA. This interaction is said to induce destabilization of the target mRNA and/or inhibition of protein synthesis. Recognition between a miRNA and its target is mainly controlled by a sequence of about 7 bases, situated in the 5′ portion of the miRNA (hereinafter, recognition sequence or seed). Accordingly, each miRNA would have the capacity to regulate the stability of a wide range of separate mRNAs. 
     To date, more than 750 miRNAs have been characterized in humans, where they are said to regulate more than 30% of the transcripts. Regulation by the miRNAs therefore appears to be a major regulation of gene expression, the impact of which has been underestimated until now (Berezikov, E. et al. (2005)  Cell  120, 21-24; Xie, X. et al. (2005)  Nature  434, 338-345). 
     The miRNAs are transcribed in the nucleus in the form of long precursors. They undergo a first maturation in the nucleus to give a precursor of miRNA (pre-miRNA) possessing a smaller hairpin structure. This precursor is exported from the nucleus to the cytoplasm where it will undergo a final maturation. Degradation of its loop by the enzyme Dicer generates two single-stranded miRNAs (a 5p strand and a 3p strand); the so-called mature strand is managed by a multi-protein complex (the RISC complex: RNA induced silencing complex) which interacts with the noncoding 3′ portion of the target mRNAs, whereas the so-called “star” complementary strand will undergo a degradation; the complementary strand of a miRNA miR-xy, miR-xy-z or let-7x is designated, respectively, miR-xy*, miR-xy-z* or let-7x*. 
     Recent studies have demonstrated the importance of the microRNAs in the mouse in the mechanisms of differentiation and morphogenesis; in particular in embryonic development and the proliferation of the precursors of the epithelial cells of the epidermis (Lena, A. M. et al. (2008)  Cell Death Differ  15, 1187-1195; Yi, R. et al. (2008)  Nature  452, 225-229) or in lung development (Lu, Y. et al. (2007)  Dev Biol  310, 442-453 (2007); Harris, K. S. et al. (2006)  Proc Natl Acad Sci USA  103, 2208-2213; Lu, Y. et al. (2008)  Proc Am Thorac Soc  5, 300-304). More precisely, Lena et al. demonstrated the involvement of the miRNAs of the locus miR-17-92 in pulmonary morphogenesis in the mouse. Although there is proof of the involvement of miRNAs during pulmonary morphogenesis in the mouse, their precise role(s) and their mechanisms of action have yet to be investigated. 
     Finally, several studies suggest a particular role of certain miRNAs in diseases such as cancers, cardiac hypertrophy, diabetes or certain viral infections (Triboulet, R. et al. (2007)  Science  315, 1579-1582; Calin, G. A. &amp; Croce, C. M. (2006)  Nat Rev Cancer  6, 857-866; Grassmann, R. &amp; Jeang, K. T. (2008)  Biochim Biophys Acta  1779, 706-711; Latronico, M. V., (2008)  Physiol Genomics  34, 239-242; Poy, M. N. et al. (2004)  Nature  432, 226-230). 
     To date, no study has demonstrated the role or involvement of miRNAs in the regeneration and differentiation of ciliated epithelia, such as the airway epithelium, and the control of ciliogenesis in vertebrates. 
     SUMMARY OF THE INVENTION 
     Therefore the inventors have demonstrated for the first time the involvement of certain miRNAs in the control of ciliogenesis of epithelial tissues in vertebrates and, in particular, in the regeneration and differentiation of human airway epithelial cells in a mucociliary surface epithelium. 
     More particularly, the inventors used different experimental approaches combining high-throughput sequencing of miRNAs, miRNA biochips as well as quantitative RT-PCR and identified the miRNAs involved specifically in different stages of differentiation of the human airway epithelium and of ciliated epidermal cells of embryos of the frog  Xenopus laevis , namely signatures of the specific miRNAs 1) of the proliferation step, 2) of cellular polarization and 3) of terminal differentiation and of ciliogenesis. 
     They also confirmed the role of the miRNAs thus identified in the control of ciliogenesis of epithelial tissues notably via repression of the DLL1 Notch ligand. 
     They thus showed that the role of the microRNAs demonstrated in regeneration and ciliogenesis of a human airway epithelial tissue could be extrapolated to the mechanism of ciliogenesis of any multiciliated epithelial tissue in vertebrates. 
     It has thus been demonstrated that 63 miRNAs are expressed or repressed and/or are present in a significant amount in healthy airway epithelial tissue during regeneration and differentiation (see Tables III, IV, V and VI). The finding of a change in expression of one or more miRNAs in a sick individual relative to a healthy individual is an indicator of a defect of regulation of the expression of one or more genes; this change can therefore be compensated by administering the underexpressed miRNA or miRNAs and/or by administering the antagomirs of the overexpressed miRNA or miRNAs. 
     The present invention thus finds applications for evaluating the capacity for regeneration and differentiation, and thus for leading to functional ciliogenesis, of the ciliated epithelial tissue of a subject; the invention also makes it possible to evaluate the capacity for regeneration and/or differentiation of an airway epithelial tissue of said subject; the method according to the invention is also of particular interest in the area of in vitro and in vivo diagnostics. The present invention thus relates to a method of evaluating the capacity of a ciliated epithelial tissue to lead to functional ciliogenesis in a vertebrate, notably mammalian, subject, preferably human, characterized in that it comprises the steps of: 
     (i) quantitative measurement of the level of expression of the miRNAs of the ciliated epithelial tissue of said subject; 
     (ii) establishment of the expression profile of the miRNAs of the ciliated epithelial tissue of said subject; 
     (iii) comparison of the expression profile of the miRNAs of said subject with the expression profile of miRNAs of healthy ciliated epithelial tissue of one or more other subjects, said profile comprising some or all of the miRNAs in Table I given below; 
     (iv) identification of at least one miRNA, the level of expression of which by said subject differs by at least a factor of 2 relative to the level of expression of the same miRNA by said other subject(s), i.e. for which any one of the expression levels represents at least twice the other level of expression; and 
     (v) demonstration of a defect in capacity to lead to functional ciliogenesis of a ciliated epithelial tissue connected with an abnormality in expression of at least one miRNA of said subject if at least one miRNA of said profile established in step (ii) has a level of expression that differs by at least a factor of 2 relative to the level of expression of the same miRNA in the expression profile in Table I. When the level of expression is expressed in log 2 (as in Table I), this signifies that a defect in the capacity for regeneration and/or differentiation, and therefore for ciliogenesis, of a ciliated epithelial tissue connected with an abnormality of expression of at least one miRNA is observed when the level of expression in log 2 of the test subject varies by at least one unit relative to the expression profile in one or more other healthy subjects. 
     Application of the method according to the invention requires establishment of the expression profile of the miRNAs of the ciliated epithelial tissue of a subject for whom we wish to establish a diagnosis relating to the capacity for regeneration and/or differentiation of a ciliated epithelial tissue and of the expression profile of the miRNAs of the ciliated epithelial tissue of one or more healthy subjects, i.e. selected for not having a disorder of differentiation and/or regeneration and of ciliogenesis of the ciliated epithelial tissue. 
     According to another of its objects, the present invention relates to a method of evaluating the capacity for regeneration and/or differentiation and for leading to functional ciliogenesis of an airway epithelial tissue of a mammalian subject, preferably human, characterized in that it comprises the steps of: 
     (i) quantitative measurement of the level of expression of the miRNAs of the airway epithelial tissue of said subject; 
     (ii) establishment of the expression profile of the miRNAs of the airway epithelial tissue of said subject; 
     (iii) comparison of the expression profile of the miRNAs of said subject with the expression profile of the miRNAs of said healthy airway epithelial tissue of one or more other subjects, said profile comprising some or all of the miRNAs in Table I given below; 
     (iv) identification of at least one miRNA, the level of expression of which by said subject differs by at least a factor of 2 relative to the level of expression of the same miRNA by said other subject(s), i.e. for which any one of the expression levels represents at least twice the other level of expression; and 
     (v) demonstration of a defect in the capacity for regeneration and/or differentiation of an airway epithelial tissue connected with an abnormality of expression of at least one miRNA of said subject if at least one miRNA of said profile established in step (ii) has a level of expression that differs by at least a factor of 2 relative to the level of expression of the same miRNA in the expression profile in Table I. 
     DEFINITIONS 
     
         
         
           
             “Subject” means a vertebrate individual, in particular mammalian, and preferably human. Preferably, the subject for which we wish to establish a diagnosis relating to the capacity of a ciliated epithelial tissue to lead to functional ciliogenesis, it can more specifically be a matter of diagnosing the capacity for regeneration and/or differentiation of an airway epithelial tissue and the healthy subject or subjects belong to the same species. 
             In the context of the present invention, the terms “ciliated” and “multiciliated” are used indiscriminately, it being understood that the epithelial tissues in question are such that their cells bear several cilia. 
             Expression profile of the miRNAs in a given tissue means all of the miRNAs having a level of expression greater than or equal to a selected value. 
             The level of expression of a miRNA in a cell or a tissue is determined by measuring the miRNAs present in the cell or tissue. 
             The level of expression of a miRNA can be measured by any technique known by a person skilled in the art; we may notably mention, after a step of RNA extraction, high-throughput sequencing of the miRNAs, sequencing by NASBA (nucleic acid strand based amplification), by primer extension, or DNA chips permitting hybridization of the miRNAs. 
             The level of expression of the miRNAs can be expressed by different means such as: 
             the level of intensity of expression in log 2, this value is representative of the amount of miRNA present in a cell or a tissue; for establishment of an expression profile, it is preferable to use the miRNAs that have a level of intensity of expression in log 2 greater than or equal to 3; 
           
         
       
    
     This level of intensity of expression can be calculated by different means depending on the technique used for measuring the miRNAs expressed. 
     In the case of measurement of fluorescence on chips of the Agilent type (see the examples given below), measurement of the level of expression corresponds to an intensity of fluorescence, from which log 2 is then calculated. In the case of high-throughput sequencing, the level of intensity of expression counts the number of times the sequence of a miRNA is sequenced, this number is normalized relative to the total number of sequences, and then its log 2 is calculated.
         the abundance, which represents the percentage expression of a miRNA in a cell or a tissue relative to the total amount of miRNAs expressed in the same cell or the same tissue, in this case the miRNAs whose abundance is greater than or equal to 0.1%, preferably 0.5%, more preferably 1%, will be retained.       

     Preferably, the values characterizing the level of expression are expressed in log 2. 
     Table I given below describes the expression profile in which the level of expression is expressed as the level of intensity of expression in log 2 of the miRNAs of a healthy human airway epithelial tissue: 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                   
                   
                   
                 Level of intensity of 
               
               
                   
                   
                   
                 expression in log2 
               
               
                   
                   
                 Sequence number 
                 At the differentiated 
               
               
                   
                 Name of the 
                 of the miRNA 
                 stage (WD) 
               
               
                   
                 miRNA 
                 (SEQ ID) 
                 measured in HTS 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 hsa-miR-100 
                 1 
                 9.00 
               
               
                   
                 hsa-miR-106b 
                 2 
                 5.39 
               
               
                   
                 hsa-miR-125a-5p 
                 3 
                 14.08 
               
               
                   
                 hsa-miR-130a 
                 4 
                 11.98 
               
               
                   
                 hsa-miR-140-3p 
                 5 
                 13.12 
               
               
                   
                 hsa-miR-141 
                 6 
                 9.75 
               
               
                   
                 hsa-miR-148a 
                 7 
                 8.97 
               
               
                   
                 hsa-miR-151-5p 
                 8 
                 10.22 
               
               
                   
                 hsa-miR-15a 
                 9 
                 7.68 
               
               
                   
                 hsa-miR-16 
                 10 
                 5.35 
               
               
                   
                 hsa-miR-17 
                 11 
                 11.61 
               
               
                   
                 hsa-miR-181a 
                 12 
                 0.01 
               
               
                   
                 hsa-miR-191 
                 13 
                 16.82 
               
               
                   
                 hsa-miR-193b 
                 14 
                 11.67 
               
               
                   
                 Hsa-miR-1975 
                 15 
                 11.22 
               
               
                   
                 hsa-miR-200a 
                 16 
                 10.96 
               
               
                   
                 hsa-miR-200b 
                 17 
                 10.64 
               
               
                   
                 hsa-miR-200c 
                 18 
                 14.57 
               
               
                   
                 hsa-miR-203 
                 19 
                 14.55 
               
               
                   
                 hsa-miR-205 
                 20 
                 15.24 
               
               
                   
                 hsa-miR-21 
                 21 
                 8.09 
               
               
                   
                 Hsa-miR-21* 
                 73 
                 10.49 
               
               
                   
                 hsa-miR-210 
                 22 
                 9.29 
               
               
                   
                 hsa-miR-22 
                 23 
                 11.22 
               
               
                   
                 hsa-miR-224 
                 24 
                 14.10 
               
               
                   
                 hsa-miR-23a 
                 25 
                 15.35 
               
               
                   
                 hsa-miR-23b 
                 26 
                 9.35 
               
               
                   
                 hsa-miR-25 
                 27 
                 3.52 
               
               
                   
                 hsa-miR-26a 
                 28 
                 7.75 
               
               
                   
                 hsa-miR-26b 
                 29 
                 6.81 
               
               
                   
                 hsa-miR-27b 
                 30 
                 14.81 
               
               
                   
                 hsa-miR-29a 
                 31 
                 14.53 
               
               
                   
                 hsa-miR-29c 
                 32 
                 9.74 
               
               
                   
                 hsa-miR-30b 
                 33 
                 0.01 
               
               
                   
                 hsa-miR-30c 
                 34 
                 10.87 
               
               
                   
                 hsa-miR-30d 
                 35 
                 8.76 
               
               
                   
                 hsa-miR-30e 
                 36 
                 12.74 
               
               
                   
                 hsa-miR-31 
                 37 
                 11.83 
               
               
                   
                 hsa-miR-31* 
                 89 
                 11.18 
               
               
                   
                 hsa-miR-34a 
                 38 
                 13.75 
               
               
                   
                 hsa-miR-34b 
                 39 
                 10.65 
               
               
                   
                 Hsa-miR-34b* 
                 91 
                 14.29 
               
               
                   
                 hsa-miR-34c-5p 
                 40 
                 0.01 
               
               
                   
                 hsa-miR-365 
                 41 
                 2.78 
               
               
                   
                 hsa-miR-374a 
                 42 
                 11.87 
               
               
                   
                 hsa-miR-378 
                 43 
                 11.70 
               
               
                   
                 hsa-miR-425 
                 44 
                 9.53 
               
               
                   
                 hsa-miR-429 
                 45 
                 15.11 
               
               
                   
                 hsa-miR-449a 
                 46 
                 12.24 
               
               
                   
                 hsa-miR-449b 
                 47 
                 14.56 
               
               
                   
                 hsa-miR-449c 
                 201 
                 10.98 
               
               
                   
                 hsa-miR-574-3p 
                 48 
                 13.42 
               
               
                   
                 hsa-miR-92b 
                 49 
                 0.01 
               
               
                   
                 hsa-miR-939 
                 50 
                 5.43 
               
               
                   
                 hsa-miR-96 
                 51 
                 12.65 
               
               
                   
                 hsa-miR-99a 
                 52 
                 9.00 
               
               
                   
                 hsa-let-7a 
                 157 
                 4.31 
               
               
                   
                 hsa-let-7b 
                 158 
                 11.28 
               
               
                   
                 hsa-let-7c 
                 159 
                 7.86 
               
               
                   
                 hsa-let-7e 
                 160 
                 7.60 
               
               
                   
                 hsa-let-7f 
                 161 
                 5.35 
               
               
                   
                 hsa-let-7g 
                 162 
                 12.40 
               
               
                   
               
             
          
         
       
     
     The method according to the invention can have an additional step consisting of comparing the expression profile of microRNAs of ciliated epithelial tissue, notably respiratory, of the subject for which we desire to establish a diagnosis relating to the capacity to control functional ciliogenesis of said tissue, notably the capacity for regeneration and/or differentiation, with an expression profile of miRNAs of healthy ciliated epithelial tissue of one or more subjects established at a particular stage of differentiation, such a profile can be established with Table IV. 
     The present invention thus relates to at least one miRNA identified by the method according to the invention selected from hsa-miR-100, hsa-miR-106b, hsa-miR-125a-5p, hsa-miR-130a, hsa-miR-140-3p, hsa-miR-141, hsa-miR-151-5p, hsa-miR-15a, hsa-miR-16, hsa-miR-17, hsa-miR-181a, hsa-miR-191, hsa-miR-193b, hsa-miR-1975, hsa-miR-200a, hsa-miR-200b, hsa-miR-200c, hsa-miR-203, hsa-miR-205, hsa-miR-21, hsa-miR-210, hsa-miR-22, hsa-miR-224, hsa-miR-23a, hsa-miR-23b, hsa-miR-25, hsa-miR-26a, hsa-miR-26b, hsa-miR-27b, hsa-miR-29a, hsa-miR-29c, hsa-miR-30b, hsa-miR-30c, hsa-miR-30d, hsa-miR-30e, hsa-miR-31, hsa-miR-34a, hsa-miR-34b, hsa-miR-34c-5p, hsa-miR-365, hsa-miR-374a, hsa-miR-378, hsa-miR-425, hsa-miR-429, hsa-miR-449a, hsa-miR-449b, hsa-miR-449c, hsa-miR-574-3p, hsa-miR-92b, hsa-miR-939, hsa-miR-96, hsa-miR-99a, hsa-let-7a, hsa-let-7b, hsa-let-7c, hsa-let-7e, hsa-let-7f and hsa-let-7g of sequence SEQ ID No. 1 to 6, 8 to 52, 157 to 162 and 201 (see Table I below), their “star” complementary strand of sequence SEQ ID No. 53 to 58, 60 to 104, 163 to 168 and 202, or the complementary sequence strand optionally modified chemically, and their precursor of sequence SEQ ID No. 105 to 110, 112 to 156, 169 to 174, 193 to 200 and 203 for use for the prevention and/or treatment of disorders associated with a dysfunction of the cilia of ciliated epithelial tissue. 
     Ciliated epithelial tissue means a tissue whose cells bear cilia on their apical surface; in mammals, it is notably the airway epithelium or the epithelium of the Fallopian tubes and the endometrium of the uterus, of the choroid plexus and ependymal cells in the brain, and of the spermatozoa, rete testis and vas deferens in the male. 
     Complementary sequence strand of a given first single-stranded nucleic acid fragment means the single-stranded nucleic acid fragment whose sequence is the complement of the sequence of said first fragment and is capable of pairing with said first fragment. 
     In the context of the invention, chemically modified complementary-sequence strands can be used, i.e. their sequence comprises one or more bases that have been modified chemically, in order to improve their intracellular and extracellular stability and make them less sensitive to hydrolysis in acid or basic conditions as well as under the action of nucleases; the modifications that are conceivable are notably those listed for the interfering RNAs (siRNA) in the review of T. M. Rana (Nature Reviews, 2007, Vol. 8: 23-36) or as described in application WO 2007/021896; in particular, complementary-sequence strands can comprise a chemically modified nucleotide selected from the nucleotides modified in 2′ such as a 2′-deoxy, 2′-deoxy-2′-fluoro, 2′-O-methyl, 2′-O-methoxyethyl (2′-O-MOE), 2′-O-aminopropyl (2′-OAP), 2′-O-dimethylaminoethyl (2′-O-DMAOE), 2′-O-dimethylaminopropyl (2′-O-DMAP), 2′-O-dimethylaminoethyloxyethyl (2′-O-DMAEOE) or 2′-O—N-methylacetamido (2′-O-NMA) base. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE II 
               
             
             
               
                   
               
               
                 miRNAs according to the invention and reference of their 
               
               
                 nucleotide sequence, of the nucleotide sequence of their 
               
               
                 complementary strand and of that of their precursor 
               
             
          
           
               
                 Name and Sequence 
                 Name and sequence 
                 Sequence of the 
               
               
                 (SEQ ID number) 
                 (SEQ ID number) of the 
                 precursor (SEQ 
               
               
                 of the miRNAs 
                 complementary strand 
                 ID number) 
               
               
                   
               
             
          
           
               
                 hsa-miR-100 
                 1 
                 hsa-miR-100* 
                 53 
                 105 
               
               
                 hsa-miR-106b 
                 2 
                 hsa-miR-106b* 
                 54 
                 106 
               
               
                 hsa-miR-125a-5p 
                 3 
                 hsa-miR-125a-3p 
                 55 
                 107 
               
               
                 hsa-miR-130a 
                 4 
                 hsa-miR-130a* 
                 56 
                 108 
               
               
                 hsa-miR-140-3p 
                 5 
                 hsa-miR-140-5p 
                 57 
                 109 
               
               
                 hsa-miR-141 
                 6 
                 hsa-miR-141* 
                 58 
                 110 
               
               
                 hsa-miR-148a 
                 7 
                 hsa-miR-148a* 
                 59 
                 111 
               
               
                 hsa-miR-151-5p 
                 8 
                 hsa-miR-151-3p 
                 60 
                 112 
               
               
                 hsa-miR-15a 
                 9 
                 hsa-miR-15a* 
                 61 
                 113 
               
               
                 hsa-miR-16 
                 10 
                 hsa-miR-16* 
                 62 
                 114, 193 
               
               
                 hsa-miR-17 
                 11 
                 hsa-miR-17* 
                 63 
                 115 
               
               
                 hsa-miR-181a 
                 12 
                 hsa-miR-181a* 
                 64 
                 116, 194 
               
               
                 hsa-miR-191 
                 13 
                 hsa-miR-191* 
                 65 
                 117 
               
               
                 hsa-miR-193b 
                 14 
                 hsa-miR-193b* 
                 66 
                 118 
               
               
                 Hsa-miR-1975 
                 15 
                 Hsa-miR-1975* 
                 67 
                 119 
               
               
                 hsa-miR-200a 
                 16 
                 hsa-miR-200a* 
                 68 
                 120 
               
               
                 hsa-miR-200b 
                 17 
                 hsa-miR-200b* 
                 69 
                 121 
               
               
                 hsa-miR-200c 
                 18 
                 hsa-miR-200c* 
                 70 
                 122 
               
               
                 hsa-miR-203 
                 19 
                 hsa-miR-203* 
                 71 
                 123 
               
               
                 hsa-miR-205 
                 20 
                 hsa-miR-205* 
                 72 
                 124 
               
               
                 hsa-miR-21 
                 21 
                 hsa-miR-21* 
                 73 
                 125 
               
               
                 hsa-miR-210 
                 22 
                 hsa-miR-210* 
                 74 
                 126 
               
               
                 hsa-miR-22 
                 23 
                 hsa-miR-22* 
                 75 
                 127 
               
               
                 hsa-miR-224 
                 24 
                 hsa-miR-224* 
                 76 
                 128 
               
               
                 hsa-miR-23a 
                 25 
                 hsa-miR-23a* 
                 77 
                 129 
               
               
                 hsa-miR-23b 
                 26 
                 hsa-miR-23b* 
                 78 
                 130 
               
               
                 hsa-miR-25 
                 27 
                 hsa-miR-25* 
                 79 
                 131 
               
               
                 hsa-miR-26a 
                 28 
                 hsa-miR-26a* 
                 80 
                 132, 195 
               
               
                 hsa-miR-26b 
                 29 
                 hsa-miR-26b* 
                 81 
                 133 
               
               
                 hsa-miR-27b 
                 30 
                 hsa-miR-27b* 
                 82 
                 134 
               
               
                 hsa-miR-29a 
                 31 
                 hsa-miR-29a* 
                 83 
                 135 
               
               
                 hsa-miR-29c 
                 32 
                 hsa-miR-29c* 
                 84 
                 136 
               
               
                 hsa-miR-30b 
                 33 
                 hsa-miR-30b* 
                 85 
                 137 
               
               
                 hsa-miR-30c 
                 34 
                 hsa-miR-30c* 
                 86 
                 138, 196 
               
               
                 hsa-miR-30d 
                 35 
                 hsa-miR-30d* 
                 87 
                 139 
               
               
                 hsa-miR-30e 
                 36 
                 hsa-miR-30e* 
                 88 
                 140 
               
               
                 hsa-miR-31 
                 37 
                 hsa-miR-31* 
                 89 
                 141 
               
               
                 hsa-miR-34a 
                 38 
                 hsa-miR-34a* 
                 90 
                 142 
               
               
                 hsa-miR-34b 
                 39 
                 hsa-miR-34b* 
                 91 
                 143 
               
               
                 hsa-miR-34c-5p 
                 40 
                 hsa-miR-34c-3p 
                 92 
                 144 
               
               
                 hsa-miR-365 
                 41 
                 hsa-miR-365* 
                 93 
                 145, 197 
               
               
                 hsa-miR-374a 
                 42 
                 hsa-miR-374a* 
                 94 
                 146 
               
               
                 hsa-miR-378 
                 43 
                 hsa-miR-378* 
                 95 
                 147 
               
               
                 hsa-miR-425 
                 44 
                 hsa-miR-425* 
                 96 
                 148 
               
               
                 hsa-miR-429 
                 45 
                 hsa-miR-429* 
                 97 
                 149 
               
               
                 hsa-miR-449a 
                 46 
                 hsa-miR-449a* 
                 98 
                 150 
               
               
                 hsa-miR-449b 
                 47 
                 hsa-miR-449b* 
                 99 
                 151 
               
               
                 hsa-miR-449c 
                 201 
                 hsa-miR-449c* 
                 202 
                 203 
               
               
                 hsa-miR-574-3p 
                 48 
                 hsa-miR-574-5p 
                 100 
                 152 
               
               
                 hsa-miR-92b 
                 49 
                 hsa-miR-92b* 
                 101 
                 153 
               
               
                 hsa-miR-939 
                 50 
                 hsa-miR-939* 
                 102 
                 154 
               
               
                 hsa-miR-96 
                 51 
                 hsa-miR-96* 
                 103 
                 155 
               
               
                 hsa-miR-99a 
                 52 
                 hsa-miR-99a* 
                 104 
                 156 
               
               
                 hsa-let-7a 
                 157 
                 hsa-let-7a* 
                 163 
                 169, 198, 199 
               
               
                 hsa-let-7b 
                 158 
                 hsa-let-7b* 
                 164 
                 170 
               
               
                 hsa-let-7c 
                 159 
                 hsa-let-7c* 
                 165 
                 171 
               
               
                 hsa-let-7e 
                 160 
                 hsa-let-7e* 
                 166 
                 172 
               
               
                 hsa-let-7f 
                 161 
                 hsa-let-7f* 
                 167 
                 173, 200 
               
               
                 hsa-let-7g 
                 162 
                 hsa-let-7g* 
                 168 
                 174 
               
               
                   
               
             
          
         
       
     
     The miRNAs according to the present invention are thus of particular interest for the prevention and/or treatment of so-called primary ciliopathies, i.e. which are directly associated with a dysfunction of the cilia, these primary ciliopathies are notably:
         primary ciliary dyskinesia or Kartagener syndrome;   situs invertus;   male infertility (motility of the spermatozoa) and female infertility (e.g. ectopic pregnancies);   Alstrom syndrome;   Bardet-Biedl syndrome;   Meckel-Gruber syndrome;   polycystic kidney;   retinal degeneration;   Senior-Løken syndrome.       

     The miRNAs according to the present invention are also of interest for the prevention and/or treatment of so-called secondary ciliopathologies, i.e. which are associated with a defect of function of the cilia such as:
         mucoviscidosis;   chronic obstructive pulmonary disease (COPD);   asthma;   bronchiolitis;   respiratory infections of viral origin.       

     The use according to the present invention therefore finds applications more particularly in the prevention and/or treatment of pathologies involving a disorder of regeneration and/or of differentiation of the airway epithelium; these pathologies are notably chronic and/or hereditary respiratory diseases such as chronic obstructive pulmonary disease (COPD), mucoviscidosis, asthma, primary ciliary dyskinesia, chronic inflammations and infections of the respiratory passages and respiratory failure. 
     The chronic and/or hereditary respiratory diseases (e.g. COPD, mucoviscidosis, asthma, PCD, allergic rhinitis etc.) represent a major public health problem, the fourth cause of mortality in the industrialized countries, and with rapidly increasing prevalence, hence the urgent need for better understanding of the causes and mechanisms of these diseases so that their treatments can be better targeted. 
     Asthma is the commonest of the chronic respiratory diseases in children (5 to 20%) and represents one of the major causes of hospitalization. The upsurge in respiratory allergies and the increase in industrial pollution contribute to the large increase in cases of asthma in the general population (0 van Schayck, et al. IPAG DIAGNOSIS &amp; MANAGEMENT HANDBOOK. Chronic Airways Diseases. A Guide for Primary Care Physicians. 1-34, 2005). 
     The COPDs are a group of respiratory diseases associated with high morbidity and high mortality. COPDs are caused by inhaled toxic particles, tobacco being the most representative, which will lead to inflammation and to chronic infections that weaken the respiratory tissue. About 15% of smokers are likely to develop a COPD in their life. The World Health Organization estimates that there are nearly 1.1 billion smokers in the world, with a prevalence of COPD from 0.8 to 6% of the world population. Studies predict that in 2020, COPDs will represent the third cause of mortality in the world. Although the causes and mechanisms of these diseases are still largely unknown, it is probable that other factors (genetic, epigenetic) are likely to influence the development of COPD (0 van Schayck, et al. 2005). 
     Mucoviscidosis is the commonest hereditary genetic disease in the Caucasian population (1 birth out of 2500), affecting the exocrine glands and therefore all of the secretory epithelial tissue of the various organs (lungs, pancreas, liver, sweat glands, intestines). Defects of ion transport through the epithelia lead to a thickening of the mucus, notably responsible for inflammation and chronic respiratory infections, resulting in irreversible tissue destruction and to severe respiratory failure. There is no treatment for curing this disease, but advances in scientific and medical knowledge have made it possible to establish symptomatic treatments that have increased patients&#39; life expectancy from 3 years in the 1960s to about 45 years today. 
     Primary ciliary dyskinesia (PCD) is a rare recessive autosomal disease (1 birth out of 15000) causing a defect of mobility of the cilia of the airway epithelium leading to defective mucociliary clearance, inflammations and chronic infections and irreversible tissue destruction. 
     The interest of these miRNAs with a view to treatment of diseases involving a disorder of regeneration and/or of differentiation of the airway epithelium is confirmed by the fact that these miRNAs regulate genes that are known to be involved in the regeneration and/or differentiation of the airway epithelium (see example III below). 
     In the context of the invention, it is preferable to use miRNAs that are present in significant quantity within the ciliated epithelial tissue during the process of ciliogenesis (preferably, the abundance of which is at least 1% of the total miRNAs, see Table III). Thus, it is preferable to use at least one miRNA selected from hsa-miR-34a (SEQ ID No. 38), hsa-miR-34b (SEQ ID No. 39), hsa-miR-34c-5p (SEQ ID No. 40), hsa-miR-449a (SEQ ID No. 46), hsa-miR-449b (SEQ ID No. 47), hsa-miR-449b* (SEQ ID No. 99), hsa-miR-449c (SEQ ID No. 201), hsa-miR-92b (SEQ ID No. 49), hsa-miR-1975 (SEQ ID No. 15), hsa-miR-99a (SEQ ID No. 52), hsa-miR-191 (SEQ ID No. 13), hsa-miR-378 (SEQ ID No. 43), hsa-miR-23b (SEQ ID No. 26), hsa-miR-125a-5p (SEQ ID No. 3), hsa-miR-203 (SEQ ID No. 19), hsa-miR-574-3p (SEQ ID No. 48), hsa-miR-29c (SEQ ID No. 32), hsa-miR-140-3p (SEQ ID No. 5), hsa-miR-205 (SEQ ID No. 20), hsa-miR-23a (SEQ ID No. 25), hsa-miR-31 (SEQ ID No. 37), hsa-miR-31* (SEQ ID No. 89), hsa-miR-21 (SEQ ID No. 21), hsa-miR-17 (SEQ ID No. 11), hsa-miR-29a (SEQ ID No. 31), hsa-miR-193b (SEQ ID No. 14), hsa-miR-210 (SEQ ID No. 22) and hsa-miR-130a (SEQ ID No. 4), their “star” complementary strand of sequence SEQ ID No. 55 to 57, 63, 65 to 67, 71 to 74, 77, 78, 83, 84, 90 to 92, 95, 98, 100, 101, 104 and 202, their complementary sequence strand optionally chemically modified, and their precursors of SEQ ID No. 107 to 109, 115, 117 to 119, 123 to 126, 129, 130, 135, 136, 141 to 144, 147, 151 to 153, 156 and 203. 
     Among these miRNAs, those whose expression is induced can be distinguished from those whose expression is repressed (Table IV); in order to reproduce a miRNA expression profile comparable to that of a healthy individual, it appears to be advantageous to use one or more miRNAs whose expression is induced and/or one or more miRNA antagomirs whose expression is repressed during the process of ciliogenesis of the ciliated epithelial tissues and, notably, of regeneration and of differentiation of the airway epithelial tissue. Thus, according to an advantageous variant of the invention, at least one miRNA is used according to the invention, selected from hsa-miR-34a (SEQ ID No. 38), hsa-miR-34b (SEQ ID No. 39), hsa-miR-34c-5p (SEQ ID No. 40), hsa-miR-449a (SEQ ID No. 46), hsa-miR-449b (SEQ ID No. 47), hsa-miR-449b* (SEQ ID No. 99), hsa-miR-449c (SEQ ID No. 201), hsa-miR-92b (SEQ ID No. 49), hsa-miR-1975 (SEQ ID No. 15), hsa-miR-99a (SEQ ID No. 52), hsa-miR-191 (SEQ ID No. 13), hsa-miR-378 (SEQ ID No. 43), hsa-miR-23b (SEQ ID No. 26), hsa-miR-125a-5p (SEQ ID No. 3), hsa-miR-203 (SEQ ID No. 19), and their precursors of sequence SEQ ID No. 107, 117, 119, 123, 130, 142 to 144, 147, 150, 151, 153, 156 and 203 and/or at least one “star” complementary strand of the miRNAs selected from hsa-miR-205, hsa-miR-31, hsa-miR-21, hsa-miR-17, hsa-miR-29a, hsa-miR-193b, hsa-miR-31*, hsa-miR-210 hsa-miR-130a; these “star” complementary strands are hsa-miR-205* (SEQ ID No. 72), hsa-miR-31 and hsa-miR-31* (SEQ ID No. 37 and 89), hsa-miR-21* (SEQ ID No. 73), hsa-miR-17* (SEQ ID No. 63), hsa-miR-29a* (SEQ ID No. 83), hsa-miR-193b* (SEQ ID No. 66), hsa-miR-210* (SEQ ID No. 74), hsa-miR-130a* (SEQ ID No. 56) and their precursors of sequence SEQ ID No. 108, 115, 118, 124 to 126, 135 and 141. 
     Among said miRNAs whose expression is modulated during the process of ciliogenesis of the ciliated epithelial tissues, and notably of regeneration and/or differentiation of the airway epithelial tissue, those whose expression is induced are preferably used according to the invention: hsa-miR-34a (SEQ ID No. 38), hsa-miR-34b (SEQ ID No. 39), hsa-miR-34c-5p (SEQ ID No. 40), hsa-miR-449a (SEQ ID No. 46), hsa-miR-449b (SEQ ID No. 47), hsa-miR-449c (SEQ ID No. 201), hsa-miR-449b* (SEQ ID No. 99), hsa-miR-92b (SEQ ID No. 49), hsa-miR-1975 (SEQ ID No. 15), hsa-miR-99a (SEQ ID No. 52), hsa-miR-191 (SEQ ID No. 13), hsa-miR-378 (SEQ ID No. 43), hsa-miR-23b (SEQ ID No. 26), hsa-miR-125a-5p (SEQ ID No. 3), hsa-miR-203 (SEQ ID No. 19), and their precursors of sequence SEQ ID No. 107, 117, 119, 123, 130, 142 to 144, 147, 150, 151, 153, 156 and 203. 
     The present invention also relates to the use of expression vectors expressing at least one miRNA whose expression is induced during the process of ciliogenesis of an epithelial tissue or during the process of regeneration and/or differentiation of the airway epithelial tissue. Any expression vector capable of expressing RNAs in a eukaryotic cell and into which an expression cassette of a miRNA is cloned can be used in the context of the present invention. 
     The invention also relates to the use of miRNAs having the recognition sequence GGCAGUG (SEQ ID No. 175) positioned in region 2-7 of the miRNA, i.e. from the 2nd to the 7th nucleotide of the miRNA, or in region 3-8 of the miRNA, i.e. from the 3rd to the 8th nucleotide of the miRNA; they are notably the miRNAs hsa-miR-34a (SEQ ID No. 38), hsa-miR-34c-5p (SEQ ID No. 40), hsa-miR-449a (SEQ ID No. 46), hsa-miR-449b (SEQ ID No. 47) and hsa-miR-449c (SEQ ID No. 201). 
     The invention also relates to the use of miRNAs having the recognition sequence AAUCACU (SEQ ID No. 176) positioned in region 2-7 or in region 3-7 of the miRNA; it is notably the miRNA hsa-miR-34b (SEQ ID No. 39). 
     The invention further relates to the use of miRNAs having the recognition sequence AUCACUA (SEQ ID No. 177) positioned in region 2-7 or in region 3-7 of the miRNA; it is notably the miRNA hsa-miR-34c-3p (SEQ ID No. 40). 
     The invention finally relates to the use of at least one miRNA described above selected from the miRNAs of sequence SEQ ID No. 3-5, 8, 9, 11-15, 17, 19, 20, 23-26, 28-32, 35-37, 39-44, 46-52 and 201, their complementary strand or antagomir of sequence SEQ ID No. 55-57, 60, 61, 63-67, 69, 71, 72, 7578, 80-84, 87-89, 91-96, 98-104 and 202, optionally modified chemically, and their precursor of sequence SEQ ID No. 107-109, 112, 113, 115-119, 121, 123, 124, 127-130, 132-136, 139-141, 143-148, 150-156, 194, 195, 197 and 203 for use as a medicinal product. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Besides the arrangements given above, the invention further comprises other arrangements which will become clear from the description presented below, which refer to examples of implementing the present invention, as well as to the appended drawings in which: 
       FIGURES 
         FIG. 1  shows micrographs of primary cultures of human airway epithelial cells observed by confocal and electron microscopy, revealing the morphology of the cells marked with hematoxylin and with eosin. The cells were also immunolabeled in order to examine the expression of epithelial markers of differentiation (tubulin-β4 for the ciliated cells ( FIGS. 1E-F ), mucin MUC5AC for the mucus-secreting cells ( FIGS. 1G-H ), and cytokeratin 13 for the basal cells ( FIGS. 1I-J )). The states of differentiation were evaluated. 
         FIG. 2A  presents cumulative histograms showing the 26 miRNAs having the strongest expression in at least one of the different stages of differentiation of the human airway epithelium in 3 separate patients: ALI-D0 (D0, proliferation), ALI-D7 (D7, proliferation and polarization), ALI-FC (FC, start of ciliogenesis), ALI-WD (WD, wholly differentiated epithelium).  FIG. 2B  presents cumulative histograms showing the 22 miRNAs that have the strongest expression and are significantly modulated in at least one of the different stages of differentiation of the human airway epithelium in 3 separate patients: ALI-D0 (D0, proliferation), ALI-D7 (D7, proliferation and polarization), ALI-FC (FC, start of ciliogenesis), ALI-WD (WD, wholly differentiated epithelium). 
         FIG. 3  shows a hierarchic cluster obtained by Agilent® miRNA chips showing the variations in intensity of expression of the miRNAs expressed statistically (A&gt;8, P&lt;0.05) and modulated in at least one condition of cellular culture (1&lt;M&lt;−1) (the darker the boxes, the less the miRNAs are expressed) as a function of the states of differentiation of the cellular cultures. 
         FIG. 4  is a graph showing the correlation between the results obtained in high-throughput sequencing (HTS) and in miRNA chips (Agilent®). 
         FIG. 5  shows a histogram of the variations observed by quantitative PCR of the 5p strands of each of the miRNAs tested at each stage of differentiation as indicated on the diagram. The results show the average of 3 separate donors. 
         FIG. 6  combines two graphs showing the microRNAs regulated during ciliogenesis. Diagrams a and c show the abundance of the microRNAs as a percentage relative to the total microRNAs in undifferentiated HAEC cells (not ciliated, stage ALI-D0) (diagram a) and in an epidermal explant of  Xenopus  embryo before embryonic stage E11.5 (gastrula) and after stage E26 (tail bud) (diagram c). Diagrams b and d repeat the same data and illustrate the quantitative abundance of the miRNAs. 
         FIG. 7  presents micrographs for visualizing the specific localization of miR-449 in the ciliated cells. These tests were performed by hybridization in situ on frozen sections from culture of HAEC cells at 21 days (stage ALI-D21) (micrographs a, b, c), of human bronchial tissues (micrographs e, f, g) or from  Xenopus  embryos at the tail bud stage (micrographs h, i, j, k, l) using LNA probes labeled with digoxigenin and directed against miR-449 (micrographs a, e, f, h, i, j, l) or against miR-31 (micrograph b) and random probes (“scramble”) as negative control (micrographs c, g, i). The ciliated cells of  Xenopus  embryo were identified by immunocytolabeling with a primary antibody directed against acetylated tubulin. The LNA probes directed against miR-449 label the ciliated cylindrical cells (micrographs a, e, h). Conversely, the probes directed against miR-31 labeled the basal cells preferentially (micrograph b). The mucus-secreting cells were labeled with anti-mucin antibody MUC5AC (indicated by arrows in panel e). Diagram d illustrates the levels of expression of miR-449, miR-31 and miR-34 in the basal cells of the epithelial tissue of human respiratory passages and in ciliated cylindrical cells. 
         FIG. 8  shows a mapping (heat-map) of the microRNAs significantly regulated between pyramidal cells (ciliated+secretory) versus basal cells. The 5 microRNAs located at the top of the column are specific to pyramidal cells (ciliated+secretory); below these, the lighter the appearance of the miRNAs, the more they are specific to the basal cells. 
         FIG. 9  is a graph showing the relations between log 2  of the ratio at two stages of differentiation (abscissa) and the value of statistical significance (ordinate) for each of the 2 by 2 comparisons indicated on the diagram. The genes that are significantly overexpressed are shown in dark gray (right-hand side of the graph) and the genes that are significantly repressed are shown in medium gray (left-hand side of the graph). 
         FIG. 10  is a histogram showing the log 2  of the intensity of expression of the mRNA of caveolin-1 in each of the culture conditions investigated, as indicated on the diagram. 
         FIG. 11  is a histogram showing the effect of each of the miRNAs selected on the activity of luciferase (expressed relative to the % of the maximum effect obtained with the control vector PSICHECK) when the reporter gene of luciferase is fused to the noncoding 3′ portion of the mRNA of Cav-1 versus the control (PSICHECK). The data were normalized relative to the results obtained with a negative control miRNA. 
         FIG. 12  combines graphs illustrating the enrichment of genes containing the sequence of the recognition sequence (“seed”) common to mir-449a, mir-449b, mir-34a, mir-34b* and mir-34c. The number of genes analyzed (about 25000) is shown on the abscissa; these genes are positioned according to their level of repression or expression: the genes are shown from left to right, from the most repressed to the most induced. The ordinate represents the statistical value in log 10 of the level of enrichment (the enrichment score shown on the ordinate corresponds to the absolute value of log 10 of the value P, calculated according to a hypergeometric, binomial cumulative model described by van Dongen S et al. Nat. Methods. 2008 December; 5(12): 1023-5). The miRNA that was transfected into the HAEC cells is indicated on each graph. 
         FIG. 13  shows the result of identification, using the IPA software, of biological functions and diseases in relation to the genes that were modulated by expression of the miRNAs according to the invention. 
         FIG. 14  illustrates the inhibition of ciliogenesis by suppression of the expression of miR-449. 
       (a,b) the HEAC cells are treated several times with anti-miR-449 antagomirs or a control antagomir (20 nM) during their regeneration (generally 21 days). The percentage of ciliated cells was defined as the ratio of the number of cells positive to +tubulin-β4 relative to the number of nuclei (20 fields/filter and 3 filters/donor). Micrograph (a) shows an immunolabeling typical of HAEC cells treated with a control antagomir (Antago-Neg) or an anti-miR-449 antagomir (Antago-449). The histogram indicates the percentage of ciliated cells per field for each experimental condition (n=6, ***, P&lt;0.001, Student test). Micrograph (b) shows that the anti-miR-449 antagomir suppresses the expression of miR449a and miR-449b, but it has no effect on the expression of miR-21 (n=6, ns=not significant, **, P&lt;0.01, ***, P&lt;0.001, Student test). 
       Tests on  Xenopus : a mixture comprising 30 ng of control morpholino oligonucleotides (MO) (micrographs c, d, h) or of MO miR-449a/b/c (10 ng each) and 2.5 ng of fluorescent lysine-dextran (FLDx, colored orange/brown, micrographs c and f) or 500 pg of mRNA of TD-tomato-CAAX for tracing the cells injected (micrographs g, i) is injected into the epidermis of  Xenopus  embryos at the segmentation stage. 
       Micrographs e and f permit detection of progenitors of ciliated cells by labeling with tubulin-α with the technique of hybridization in situ. 
       Micrograph f: region depleted of miR-449 (top) shows an excess of cells positive to tubulin-α relative to the region not injected (bottom). Micrographs h and show the detection of cilia in embryos at the tadpole stage with an anti-acetylated tubulin antibody. The image is obtained in the region of the tail fin. No cilium is detected in the cells co-injected with MO miR-449 and mRNA TD-tomato-CAAX. Graph g shows the percentage of cells injected (positive for red fluorescence TD-tomato) which develop cilia in the control explant (225 cells, 8 tails) and in that modified with MO miR-449 (242 cells, 8 tails, p=0.036, Kruskall-Wallis test). 
         FIG. 15  illustrates the induction of specialization of the ciliated cells by suppression of miR-449. A mixture of MO anti-miR-449 or of control MO and of FLDx is injected in the epidermis of embryos at the segmentation stage. The embryos are fixed at the early neurula stage and then submitted to hybridization in situ with riboprobes of tubulin-α, Tex15 and Foxj1, they are then immunolabeled to reveal the presence of FLDx (fluorescent lysine-dextran). The embryos were then sectioned for better visualization of the density of progenitors of the ciliated cells in the injected areas. For the three markers, suppression of expression of the miR-449s led to an increase in progenitors of the ciliated cells. 
       The four sections of  FIG. 16  illustrate results of enrichment of the genes as explained on the website http://www.broadinstitute.org/gsea/doc/GSEAUserGuideFrame. html. The GSEA calculates an enrichment score (ES) which reflects the degree to which a gene is overexpressed within a list of given genes. A positive ES indicates enrichment of a gene on the left of the ensemble of genes (corresponding to an over-regulated gene), a negative ES indicates enrichment of a gene on the right of said ensemble of genes (corresponding to an under-regulated gene). For each section, the top panel is a graphical representation of the enrichment score of an ensemble of genes as indicated on the left. The middle part of the panel shows where the members of the ensemble of genes appear in the list (“cell cycle” or “ciliogenesis”). The bottom part of the panel shows the value of metric scheduling which measures the correlation between the expression of a gene and the cellular phenotype; a positive value indicates a correlation with the first phenotype (differentiation or overexpression of the miR-449s) and a negative value indicates a correlation with the second phenotype (not differentiated or control). All these experimental data are stored in the Base Gene Expression Omnibus under accession number GSE22147. 
         FIG. 17  presents the results showing that miR-449 targets the cell cycle and the Notch pathway. 
       Cell cycle: graph (a) shows the modulation of the activity of the reporter gene of luciferase fused to the noncoding 3′ part of the mRNA of Areg, Ccnb1, Ccne2, Cdc25a by miR-449a/b and miR-34a/c5-p. 
       Notch signalling pathway: Graph (c) shows the modulation of the activity of the reporter gene of luciferase fused to the noncoding 3′ part of the mRNA of DLL1 and Notch 1 by miR-449a/b and miR-34a/c5-p. 
       All the experiments were carried out at least twice in triplicate. The values were normalized to the internal control of  Renilla  luciferase. The error bars indicate the standard deviation. 
       Graph (b) shows the blocking of the cell cycle in phase G1 by miR-449 and miR-34. 
       Graph (d) shows the effect of inhibition of the Notch pathway by DAPT (10 μM) on the ciliogenesis of the HAEC cells. 
       Micrographs (e) and (f) show embryos at the segmentation stage, where the epidermis received an injection of a mixture of MO anti-miR-449 and of fluorescent lysine-dextran (FLDx). 
       Staining by hybridization in situ reveals the sustained expression of DLL1 in the epidermis deficient in miR-449. 
       Panel (g) shows embryos at the segmentation stage, where the epidermis received an injection of control MO, of MO anti-miR-449 and of MO DII1 or of mRNA DLL1. The cilia were stained with an anti-acetylated tubulin antibody (in red). For each condition, at least 200 cells positive to FLDx (in green), on 6 to 8 tails, have cilia (P&lt;0.03). It should be noted that the injection of mRNA of DII1 suppresses ciliogenesis, although it increases the number of progenitors of ciliated cells. Extinction of the expression of DII1 induces ciliogenesis. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Examples 
     I—Preparation of the Biological Cellular Model 
     I-A. Human Airway Epithelial Cells 
     The tests were conducted with primary cultures of healthy human airway epithelial cells isolated from nasal conchae or polyps collected from patients undergoing septoplasty, turbinectomy or polypectomy. The cells were then cultivated on a porous substrate covered with type IV collagen (Transwell® clear, polyester, 0.4 μm, Costar) at the air-liquid interface (ALI) for the purpose of inducing differentiation (Puchelle, E et al., 2006). The morphological and physiological characteristics of the airway epithelium were described in detail (Puchelle, E. et al., 2006). 
     I-A.1. Material and Methods 
     Patients and Tissue Samples 
     Inferior conchae or nasal polyps were collected from 3 patients who were to undergo turbinectomies or polypectomies for nasal obstruction or septoplasty (Dr. Castillo, ORL Department, Pasteur Hospital, Nice, France). Patients with asthma, mucoviscidosis or allergies were excluded from the study. All the procedures were approved by the ethical committee of the University of Nice-Sophia-Antipolis. 
     Isolation and Culture of Healthy Human Airway Epithelial Cells (HAECs) 
     The primary cultures of healthy HAECs derived from nasal mucosa were conducted by a method adapted from previous studies (Wu et al., 1985; Marcet et al., 2007; LeSimple et al., 2007). After excision, the tissue is immersed immediately in an equilibrated solution of salts (HBSS (without Ca 2+ /Mg 2+ ) Invitrogen) containing HEPES (25 mM, Invitrogen), 100 U/ml penicillin (Gibco, Invitrogen), 100 mg/ml streptomycin (Gibco, Invitrogen), 100 mg/ml of gentamicin sulfate (Gibco, Invitrogen), and 2.5 mg/ml of amphotericin B (Gibco, Invitrogen). After rinsing 3 times with the medium HBSS-HEPES-antibiotics, the tissue is digested with 0.1% of pronase (Sigma) at 4° C., overnight. The tissue is then carefully withdrawn from the digestion medium, and the airway epithelial cells on the surface of the nasal mucosa are detached from the stroma by gentle stirring with the medium HBSS-HEPES-antibiotics containing 10% of fetal calf serum (FCS). The cellular suspension is centrifuged at 150 g, 10 min at 4° C. and the cellular pellet is resuspended in 10% FCS-HBSS-HEPES-antibiotics and centrifuged again. The second cellular pellet is then resuspended in a medium of 10% FCS-antibiotics-Dulbecco&#39;s modified Eagle&#39;s medium (DMEM, Invitrogen) using a needle (0.8 mm) and a 10-ml syringe for dissociating the cellular aggregates. The cells are then seeded (10 4 /cm 2 ) on permeable porous supports (Transwell®, Costar, Sigma) covered with type IV collagen (Sigma) and incubated in a humidified atmosphere at 37° C., 5% CO 2 . On the next day, the culture medium is replaced with proliferation medium (BEGM) reconstituted using BEBM medium (Lonza) containing the following hormonal supplements and other growth factors: insulin, apotransferrin, epidermal growth factor (EGF), epinephrine, hydroxycortisone, 3,30,5-triiodothyronine, endothelial cell growth supplement, retinoic acid (at low concentration, about 10 nM), amphotericin B (2.5 mg/ml), streptomycin (100 mg/ml), penicillin (100 U/ml), gentamicin sulfate (50 mg/ml) and L-glutamine (2 mM). 
     Confluence of the monolayer of airway epithelial cells is typically reached after 7 days of culture. The apical surface medium is then withdrawn in order to put the cells at the air-liquid interface and the basolateral medium is replaced with differentiation medium: BEBM/DMEM of ratio (1:1) and containing the same supplements as stated above apart from the retinoic acid, which is added this time at high concentration, about 300 nM, to induce mucociliary differentiation of the airway epithelium. The experiments are then conducted on differentiated cultures having a transepithelial resistance above 500 ohm/cm 2 . 
     Immunocytochemical Labeling and Confocal and Electron Microscopy 
     The sections of membranes from airway cell cultures grown at the air-liquid interface are fixed in acetone or in methanol (10 min, −20° C.). After rinsing in PBS, the nonspecific sites are blocked in PBS-BSA 3%, then the primary antibody is incubated in PBS-BSA-1% from 1 h at room temperature to 16 h at 4° C. depending on the antibody used. After rinsing, the coupled secondary antibody, dissolved in PBS-BSA 1%, is incubated for 1 h at room temperature. After rinsing, the nuclei are labeled with DAPI and counterstained with Harris hematoxylin. After rinsing, the slides are mounted and are observed in the confocal microscope. In the case of double sequential labeling involving two mouse antibodies, a step of blocking the free sites of the primary antibodies is performed using anti-mouse anti-Fab (H+L) antibodies for 30 minutes at room temperature. 
     For electron microscopy, the cells are fixed in monosodium phosphate buffer 0.1 M containing 1.6% of glutaraldehyde. 
     Sorting of the Airway Epithelial Cells 
     After dissociation of the stroma of nasal polyps, the epithelial cells (about 20.10 6 ) are incubated in PBS-BSA-EDTA for 30 min and then incubated with labeled antibody CD151-PE and anti-TF (tissue factor)-FITC for 20 min, 4° C. (see Hajj, R. et al.,  Stem Cells  25, 139-148 (2007)). After washing twice, the cells are taken up in PBS-EDTA and incubated with DAPI for labeling the cells whose integrity has been altered. 
     Cell sorting was carried out on the FACSAria sorter (BD Biosciences) equipped with 3 lasers, blue, red and violet. Dead cells, aggregates and double cells were excluded. The doubly positive population of basal cells (CD151+/FT+) and the negative population of cylindrical cells (containing ciliated cells and mucus-secreting cells) (CD151−/FT−) were selected and sorted at a rate of 5000 events/s (30 MHz frequency). The purity and identity of the sorted cells were then verified by cytometry and immunocytochemistry. 
     I-A.2. Observation of the Morphology of the Cells Labeled with Hematoxylin and with Eosin 
     Immunolabeling was performed in order to examine the expression of epithelial markers of differentiation (tubulin-β4 for ciliated cells ( FIGS. 1E-F ), mucin MUC5AC for mucus-secreting cells ( FIGS. 1G-H ), and cytokeratin 13 for basal cells ( FIGS. 1I-J )). 
     The states of differentiation were evaluated by confocal and electron microscopy. It was decided to study four key times in differentiation: 
     (1) during the first days of establishment of the air-liquid interface (ALI-D0), the cells proliferate and form a stratified squamous epithelium; 
     (2) after 5-7 days of air-liquid interface (ALI-D7), cellular polarization begins; 
     (3) after about 14 days of air-liquid interface, the cells form a pseudostratified epithelium where the first cilia appear on the surface of the cells (ALI-FC), as well as cellular elongation, indicating the start of ciliogenesis ( FIG. 1C ); 
     (4) after about 21 days of air-liquid interface (ALI-WD), the airway epithelium becomes pseudostratified, a wholly differentiated stage in which most cells are cylindrical and ciliated, with an underlying layer of basal cells, as well as mucus-secreting cells ( FIG. 1D ). 
     After 3-4 weeks of culture, the morphological criteria and the specific markers of differentiation of the 3 cellular types of the surface airway epithelium (i.e. basal ( FIGS. 1I-J ), secreting ( FIGS. 1G-H ), and ciliated ( FIGS. 1E-F ) can be observed. 
     II—Measurement of Expression of the miRNAs in the Cells Selected During Ciliogenesis 
     The techniques of high-throughput sequencing make it possible to establish the abundance of certain miRNAs in a complex mixture. 
     Based on the number of specific sequences of a miRNA within an experimental condition, it is possible to evaluate the abundance of said miRNA within all of the miRNAs. 
     II-1. Material and Methods 
     Ciliated Epidermal Cells of Embryos of  Xenopus laevis    
     The ciliated epidermis of embryos of  Xenopus laevis  is used as a model of mucociliary epithelium as described by Hayes et al. ( Dev Biol  312 (1), 115 (2007)). 
     Extraction of Total RNAs and Quality Controls 
     The total RNAs were extracted from HAECs cultivated at the air-liquid interface at four stages of differentiation: ALI-D0 (0 day), ALI-D7 (7 days), ALI-FC (during appearance of the first cilia at about 14 days) and ALI-WD (wholly differentiated at about 21 days). The cells are lysed in reagent with Trizol® (Invitrogen). The total RNAs containing small RNAs and microRNAs are purified on Qiagen RNEasy columns (Qiagen) according to the supplier&#39;s instructions. 
     The purity and concentration of the samples of total RNAs are first evaluated using the Nanodrop spectrophotometer. The ratios 260/280 (ratio of the values of absorbance at 260 and 280 nm of a sample measured with a spectrophotometer) and 260/230 (ratio of the values of absorbance at 260 and 230 nm of a sample measured with a spectrophotometer); these ratios reflect RNA purity when they are between 1.5 and 2; they are verified and must have a value close to 2. 
     The total RNAs of embryonic cells of  Xenopus  were purified with a Qiagen RNeasy kit (Qiagen). 
     The RNAs are then loaded on an RNAnano chip (Agilent Technologie, France) and their quality (integrity and level of degradation of the RNAs) is analyzed using the Bioanalyzer System (Agilent Technologies, France). 
     High-Throughput Sequencing of microRNA 
     The total RNAs containing small RNAs and microRNAs are isolated as before. The procedure is based on the Applied Biosystems Ligase-Enhanced Genome Detection technology (LEGenD™); the SOLiD™ Small RNA Expression kit (Applied Biosystems, France) was used. With this method it is possible to convert the small RNAs of a sample into a library of double-stranded DNA; it was developed by Applied Biosystems SOLiD™ System for a new generation of high-throughput sequencing. 
     The high-throughput sequencing of the microRNAs was carried out according to the supplier&#39;s recommendations. Briefly, the total RNAs containing the small RNAs are hybridized (65° C., 10 min, then at 16° C., 5 min) and ligated (16° C., 2-16 h in a thermocycler) with the Adaptor Mix A for producing a matrix for sequencing the 5′ end of the small RNAs, or with the Adaptor Mix B for sequencing the 3′ end. The samples are then reverse-transcribed (42° C., 30 min) to synthesize the complementary DNA (cDNA). The library of small RNAs is amplified by PCR and after migration on polyacrylamide gel the amplified small RNAs are cut out and extracted from the gel according to their size (length of about 105-150 bases, according to the supplier&#39;s instructions), eluted and resuspended in nuclease-free water. The concentration of nucleic acids is then measured and normalized before proceeding with preparation of the samples for sequencing. 
     Statistical Analyses of the Data from High-Throughput Sequencing 
     The statistical analyses are performed using software R from Bioconductor® (Peter Dalgaard, Statistics and computing, Introductory statistics with R. Springer, 2002; R. Gentleman, V. J. Carey, W. Huber, R. A. Irizarry, S. Dudoit. Statistics for biology and health. Bioinformatics and computational biology solutions using R and bioconductor. Springer, 2005). 
     For each microRNA sequenced, the number of sequences of the 5p strand and of the 3p strand of the microRNA was normalized to 10 6  sequences and converted to percentage abundance of expression for each of the microRNAs. The data were then normalized according to a linear model and an empirical Bayesian method using software R. For subsequent analyses, only the microRNAs were retained for which the percentage expression (or abundance) is greater than 1% of the total of the microRNAs in at least one culture condition, with a |Log 2  Ratio| below 0.5 and an adjusted P-value below 0.05. 
     Analysis of the microRNAome by microRNA Chips (Agilent Technologies) 
     In parallel with the high-throughput sequencing of the microRNAs, the repertoire of expression of the microRNAs (microRNAome) is investigated using the technology of Agilent® microRNA chips. For this, RNA samples from the same patients as before were used, labeled and hybridized on Agilent® miRNA chips (Human miRNA Microarray v2, containing 866 human miRNAs and 89 human viral miRNAs, i.e. all the human miRNAs contained and referenced in Sanger miRBase v.12.0, Agilent Technologies, France) using the “miRNA labeling and hybridization” kit, following the supplier&#39;s instructions (Agilent Technologies). 
     Analyses of the Transcriptome by DNA Chips (Affymetrix®) 
     For the analyses of the transcriptome, the total RNAs are purified and their quality is verified as before. 
     The analysis is then performed on DNA chips, GeneChip® Human Gene 1.0 ST Array (Affymetrix®). Each of the 28869 genes is represented on the chip by about 26 probes covering the entire length of the gene. The total RNAs are labeled and hybridized using “whole Transcript (WT) Sense Target Labeling and Control Reagents, fluidics and scanning instrumentation and basic analysis software”. 
     Analyses of the Transcriptome Data Obtained by DNA Chips (Affymetrix®) 
     The data analyses are performed using the software R Bioconductor developed by the statistical consortium R. Then the data are visualized by means of the Mediante interface, an information system developed for large-scale analysis and storage of information obtained during analyses of chips (Le Brigand and Barbry, 2007). 
     For the Affymetrix® chips, the data are analyzed using the RMA (Robust Multi-Chip Average) algorithm, which performs a correction for background noise, a normalization step, and reporting of the levels of the probes. This method displays high accuracy, particularly for low values of expression, and displays higher specificity and sensitivity than many other known methods (Irizarry et al., 2003). The data are normalized according to a linear model and an empirical Bayesian method using the R Bioconductor software. Graphics in the form of Volcano plots ( FIG. 7 ) are used for showing the quantitative level of regulation of the genes expressed in log 2 as a function of their statistical significance relative to experimental replicas. 
     Hybridization In Situ 
     After fixation in 4% paraformaldehyde (Electron Microscopy Sciences), frozen sections of cellular cultures at stage ALI-D21 or of human airway tissues were acetylated, incubated overnight at 55° C. with 0.3 ng/μl of LNA probes labeled with digoxigenin targeting microRNAs (Exiquon, Woburn, Mass.) in deionized formamide 50%, 0.3 M NaCl, 20 mM Tris-HCl pH 8.0, 5 mM EDTA, 10 mM NaPO4 pH 8.0, 10% dextran sulfate, 1× of Denhardt solution, and 0.5 mg/ml of yeast RNA. 
     The sequences of the probes are: 
     for miR-449: ccagctaacaatacactgcc (SEQ. ID. No. 204) 
     for miR-31: agctatgccagcatcttgcct (SEQ. ID. No. 205) for the negative control microRNA (“scramble”): gtgtaacacgtctatacgccca (SEQ. ID. No. 206). 
     The probes were detected by sequential incubations with peroxidase conjugated with anti-digoxigenin antibodies (Roche) with the signal amplification kit “Tyramide Signal Aplificatin Plus DNP ASystem” (Perkin Elmer) on the BCIP/NBT substrate (DakoCytomation). 
     Some slides were then exposed to anti-MUC5AC mouse antibodies and detected with the “LSAB2 System-HRP” kit (Dako). The sections were counterlabeled with the eosin/saffron dye “Nuclear Fast Red”, and mounted using the Eukitt mounting medium (Electron Microscopy Sciences). 
     In  Xenopus , eggs obtained from NASCO females are fertilized in vitro, cultivated and injected as described by Marchal, L et al. ( Proc Natl Acad Sci USA  106 (41), 17437 (2009)). The cRNAs of DII1 and of centrin-2-GFP are prepared with the “Ambion mMessage Machine” kit. The membrane-bound vector Td-tomato-CAAX (donated by Chenbei Chang) is linearized with Asel and the cRNA is synthesized with Sp6 polymerase. The fluorescent lysine-dextran (FLDx, 2.5 ng/cell) is co-injected with the morpholino (MO) oligonucleotides for labeling the live embryos and an anti-fluorescein immunodetection is performed for monitoring the distribution of the MOs in the embryos. All the injections are duplicated. 
     An anti-miR-449a LNA probe labeled with mono-digoxigenin (Exiqon) was used for the hybridization in situ which was performed as described by Kloosterman et al. ( Nat Methods  3 (1), 27 (2006)). Antisense ribosomal probes of tubulin-α, DII1, Tex15 and Foxj1 were prepared as described by: Deblandre et al. ( Development  126 (21), 4715 (1999)) for tubulin-α and DII1; Hayes et al. ( Dev Biol  312 (1), 115 (2007)) for Tex15 and Pohl et al. ( Dev Genes Evol  214 (4), 200 (2004)) for Foxj1. 
     II-2. Expression of the miRNAs in the Selected Cells 
     II-2.A. HAEC Cells 
     For all the human miRNAs currently known (about 750), the inventors thus found firstly by means of the technique of high-throughput sequencing (HTS) of miRNAs that 115 miRNAs were expressed during differentiation with an intensity value above 8 (corresponding to the Log 2 of the normalized number of miRNAs sequenced). 
     Using the sequencing technique, it is possible to determine the percentage abundance of each of the miRNAs sequenced. The inventors were thus able to establish, surprisingly, that 26 miRNAs were present in the different stages of differentiation of the human airway epithelium with an abundance above 1% (shown in  FIG. 2  and in Table IIIA given below). 
     The 26 miRNAs identified cover just by themselves of the order of 80% of all the miRNAs expressed in the human airway epithelium; this quantity shows that they are involved in the process of regeneration and/or differentiation of the airway epithelial tissue. 
     A more detailed analysis of these 26 miRNAs shows that 22 are significantly regulated in at least one of the four stages of differentiation of the human airway epithelium and represent about 70% of the total of the miRNAs: 13 miRNAs are overexpressed whereas 9 miRNAs are repressed (see  FIG. 2B  and Table IV below). 
     The value of modulation (also denoted as the ratio of the level of intensity of expression in log 2 at two stages of differentiation) is calculated as the difference between the levels of intensity of expression in log 2 at the two stages of differentiation indicated at the top of each column. 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE IIIA 
               
             
             
               
                   
               
               
                 MiRNAs significantly expressed in human airway epithelium and with an abundance greater than 1% in 
               
               
                 at least one stage of differentiation, identified by high-throughput sequencing (HTS) of miRNA. 
               
             
          
           
               
                   
                   
                   
                 Modulation (ratio of the 
               
               
                   
                   
                   
                 level of intensity of 
               
               
                   
                 Level of intensity of 
                   
                 expression in log2 in two 
               
               
                   
                 expression in log2 
                 Abundance (%) 
                 stages of differentiation) 
               
             
          
           
               
                 Name 
                 Pre-mir 
                 strands 
                 D0 
                 D7 
                 FC 
                 WD 
                 D0 
                 D7 
                 FC 
                 WD 
                 D7 − D0 
                 FC − D7 
                 WD − FC 
                 WD − D0 
               
               
                   
               
             
          
           
               
                 hsa-miR-449a 
                 hsa-mir- 
                 5p 
                 4.48 
                 9.69 
                 14.90 
                 15.11 
                 0.00 
                 0.18 
                 6.49 
                 5.70 
                 5.21 
                 5.21 
                 0.21 
                 10.63 
               
               
                   
                 449a 
               
               
                 hsa-miR-449b 
                 hsa-mir- 
                 5p 
                 3.64 
                 6.96 
                 12.36 
                 12.24 
                 0.00 
                 0.03 
                 1.12 
                 0.78 
                 3.32 
                 5.40 
                 −0.12 
                 8.60 
               
               
                   
                 449b 
               
               
                 hsa-miR-449b* 
                 hsa-mir- 
                 3p 
                 6.40 
                 10.23 
                 13.59 
                 13.84 
                 0.02 
                 0.26 
                 2.62 
                 2.37 
                 3.83 
                 3.36 
                 0.26 
                 7.45 
               
               
                   
                 449b 
               
               
                 hsa-miR-449c 
                 hsa-mir- 
                   
                 1.54 
                 4.13 
                 11.57 
                 10.98 
                 0.00 
                 0.00 
                 0.32 
                 0.20 
                 2.59 
                 7.44 
                 −0.59 
                 9.44 
               
               
                   
                 449c 
               
               
                 hsa-miR-34b 
                 hsa-mir- 
                 3p 
                 7.01 
                 8.26 
                 12.43 
                 13.75 
                 0.03 
                 0.07 
                 1.17 
                 2.22 
                 1.25 
                 4.17 
                 1.32 
                 6.74 
               
               
                   
                 34b 
               
               
                 hsa-miR-34c- 
                 hsa-mir- 
                 5p 
                 7.88 
                 9.21 
                 13.23 
                 14.29 
                 0.05 
                 0.13 
                 2.05 
                 3.23 
                 1.33 
                 4.02 
                 1.06 
                 6.41 
               
               
                 5p 
                 34c 
               
               
                 hsa-miR-92b 
                 hsa-mir- 
                 3p 
                 7.49 
                 8.70 
                 12.82 
                 13.42 
                 0.04 
                 0.09 
                 1.54 
                 1.77 
                 1.21 
                 4.12 
                 0.60 
                 5.93 
               
               
                   
                 92b 
               
               
                 hsa-miR-1975 
                 hsa-mir- 
                 3p 
                 11.08 
                 13.22 
                 13.55 
                 14.01 
                 0.48 
                 2.09 
                 2.56 
                 2.67 
                 2.13 
                 0.34 
                 0.46 
                 2.93 
               
               
                   
                 1975 
               
               
                 hsa-miR-99a 
                 hsa-mir- 
                 5p 
                 9.77 
                 11.19 
                 11.96 
                 12.65 
                 0.19 
                 0.52 
                 0.85 
                 1.03 
                 1.43 
                 0.77 
                 0.69 
                 2.88 
               
               
                   
                 99a 
               
               
                 hsa-miR-191 
                 hsa-mir- 
                 5p 
                 14.67 
                 15.57 
                 16.40 
                 16.82 
                 5.71 
                 10.68 
                 18.46 
                 18.69 
                 0.90 
                 0.84 
                 0.42 
                 2.15 
               
               
                   
                 191 
               
               
                 hsa-miR-378 
                 hsa-mir- 
                 3p 
                 10.37 
                 12.53 
                 12.26 
                 11.87 
                 0.29 
                 1.30 
                 1.04 
                 0.61 
                 2.15 
                 −0.26 
                 −0.39 
                 1.50 
               
               
                   
                 378 
               
               
                 hsa-miR-23b 
                 hsa-mir- 
                 3p 
                 14.06 
                 15.35 
                 15.18 
                 15.35 
                 3.73 
                 9.19 
                 7.92 
                 6.72 
                 1.30 
                 −0.17 
                 0.16 
                 1.29 
               
               
                   
                 23b 
               
               
                 hsa-miR-125a- 
                 hsa-mir- 
                 5p 
                 12.92 
                 13.55 
                 13.29 
                 14.08 
                 1.69 
                 2.64 
                 2.13 
                 2.79 
                 0.64 
                 −0.27 
                 0.79 
                 1.16 
               
               
                 5p 
                 125a 
               
               
                 hsa-miR-203 
                 hsa-mir- 
                 3p 
                 13.49 
                 13.60 
                 13.39 
                 14.57 
                 2.53 
                 2.73 
                 2.29 
                 3.92 
                 0.11 
                 −0.21 
                 1.18 
                 1.08 
               
               
                   
                 203 
               
               
                 hsa-miR-574- 
                 hsa-mir- 
                 3p 
                 13.64 
                 14.12 
                 14.24 
                 14.56 
                 2.80 
                 3.92 
                 4.12 
                 3.90 
                 0.48 
                 0.12 
                 0.32 
                 0.92 
               
               
                 3p 
                 574 
               
               
                 hsa-miR-29c 
                 hsa-mir- 
                 3p 
                 13.66 
                 14.48 
                 14.50 
                 14.53 
                 2.84 
                 5.03 
                 4.95 
                 3.82 
                 0.82 
                 0.02 
                 0.03 
                 0.87 
               
               
                   
                 29c 
               
               
                 hsa-miR-140- 
                 hsa-mir- 
                 3p 
                 12.39 
                 12.72 
                 13.08 
                 13.12 
                 1.17 
                 1.48 
                 1.85 
                 1.44 
                 0.33 
                 0.37 
                 0.04 
                 0.73 
               
               
                 3p 
                 140 
               
               
                 hsa-miR-205 
                 hsa-mir- 
                 5p 
                 14.61 
                 15.23 
                 14.11 
                 14.55 
                 5.48 
                 8.43 
                 3.76 
                 3.87 
                 0.62 
                 −1.12 
                 0.44 
                 −0.06 
               
               
                   
                 205 
               
               
                 hsa-miR-23a 
                 hsa-mir- 
                 3p 
                 14.42 
                 14.47 
                 13.67 
                 14.10 
                 4.79 
                 4.99 
                 2.77 
                 2.83 
                 0.06 
                 −0.80 
                 0.43 
                 −0.31 
               
               
                   
                 23a 
               
               
                 hsa-miR-31 
                 hsa-mir- 
                 5p 
                 13.69 
                 13.31 
                 12.40 
                 12.74 
                 2.89 
                 2.24 
                 1.15 
                 1.10 
                 −0.37 
                 −0.91 
                 0.34 
                 −0.95 
               
               
                   
                 31 
               
               
                 hsa-miR-21 
                 hsa-mir- 
                 5p 
                 16.40 
                 15.66 
                 14.50 
                 15.24 
                 19.01 
                 11.41 
                 4.94 
                 6.26 
                 −0.74 
                 −1.16 
                 0.74 
                 −1.16 
               
               
                   
                 21 
               
               
                 hsa-miR-17 
                 hsa-mir- 
                 5p 
                 12.85 
                 12.68 
                 11.81 
                 11.61 
                 1.61 
                 1.44 
                 0.76 
                 0.50 
                 −0.17 
                 −0.87 
                 −0.20 
                 −1.24 
               
               
                   
                 17 
               
               
                 hsa-miR-29a 
                 hsa-mir- 
                 3p 
                 16.24 
                 14.90 
                 14.79 
                 14.81 
                 17.01 
                 6.72 
                 6.02 
                 4.64 
                 −1.34 
                 −0.11 
                 0.02 
                 −1.43 
               
               
                   
                 29a 
               
               
                 hsa-miR-193b 
                 hsa-mir- 
                 3p 
                 13.26 
                 12.09 
                 11.19 
                 11.67 
                 2.16 
                 0.96 
                 0.50 
                 0.52 
                 −1.17 
                 −0.90 
                 0.48 
                 −1.60 
               
               
                   
                 193b 
               
               
                 hsa-miR-31* 
                 hsa-mir- 
                 3p 
                 13.56 
                 12.91 
                 11.60 
                 11.83 
                 2.64 
                 1.69 
                 0.66 
                 0.59 
                 −0.65 
                 −1.31 
                 0.24 
                 −1.73 
               
               
                   
                 31 
               
               
                 hsa-miR-210 
                 hsa-mir- 
                 3p 
                 12.29 
                 11.33 
                 10.60 
                 10.49 
                 1.10 
                 0.57 
                 0.33 
                 0.23 
                 −0.96 
                 −0.74 
                 −0.10 
                 −1.80 
               
               
                   
                 210 
               
               
                 hsa-miR-130a 
                 hsa-mir- 
                 3p 
                 13.91 
                 12.51 
                 12.71 
                 11.98 
                 3.38 
                 1.28 
                 1.42 
                 0.65 
                 −1.40 
                 0.19 
                 −0.73 
                 −1.94 
               
               
                   
                 130a 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE IV 
               
             
             
               
                   
               
               
                 MiRNAs significantly expressed and modulated during differentiation of the airway epithelium, with 
               
               
                 an abundance greater than 1% identified by high-throughput sequencing (HTS) of miRNA. 
               
             
          
           
               
                   
                   
                   
                 Modulation (ratio of the 
               
               
                   
                   
                   
                 level of intensity of 
               
               
                   
                   
                   
                 expression in log2 in 
               
               
                   
                 Level of intensity of 
                   
                 two stages of 
               
               
                   
                 expression in log2 
                 Abundance (%) 
                 differentiation) 
               
             
          
           
               
                 Name 
                 Pre-mir 
                 strands 
                 D0 
                 D7 
                 FC 
                 WD 
                 D0 
                 D7 
                 FC 
                 WD 
                 D7 − D0 
                 FC − D7 
                 WD − FC 
                 WD − D0 
               
               
                   
               
             
          
           
               
                 hsa-miR-449a 
                 hsa-mir- 
                 5p 
                 4.48 
                 9.69 
                 14.90 
                 15.11 
                 0.00 
                 0.18 
                 6.49 
                 5.70 
                 5.21 
                 5.21 
                 0.21 
                 10.63 
               
               
                   
                 449a 
               
               
                 hsa-miR-449b 
                 hsa-mir- 
                 5p 
                 3.64 
                 6.96 
                 12.36 
                 12.24 
                 0.00 
                 0.03 
                 1.12 
                 0.78 
                 3.32 
                 5.40 
                 −0.12 
                 8.60 
               
               
                   
                 449b 
               
               
                 hsa-miR- 
                 hsa-mir- 
                 3p 
                 6.40 
                 10.23 
                 13.59 
                 13.84 
                 0.02 
                 0.26 
                 2.62 
                 2.37 
                 3.83 
                 3.36 
                 0.26 
                 7.45 
               
               
                 449b* 
                 449b 
               
               
                 hsa-miR-449c 
                 hsa-mir- 
                   
                 1.54 
                 4.13 
                 11.57 
                 10.98 
                 0.00 
                 0.00 
                 0.32 
                 0.20 
                 2.59 
                 7.44 
                 −0.59 
                 9.44 
               
               
                   
                 449c 
               
               
                 hsa-miR-34b 
                 hsa-mir- 
                 3p 
                 7.01 
                 8.26 
                 12.43 
                 13.75 
                 0.03 
                 0.07 
                 1.17 
                 2.22 
                 1.25 
                 4.17 
                 1.32 
                 6.74 
               
               
                   
                 34b 
               
               
                 hsa-miR-34c- 
                 hsa-mir- 
                 5p 
                 7.88 
                 9.21 
                 13.23 
                 14.29 
                 0.05 
                 0.13 
                 2.05 
                 3.23 
                 1.33 
                 4.02 
                 1.06 
                 6.41 
               
               
                 5p 
                 34c 
               
               
                 hsa-miR-92b 
                 hsa-mir- 
                 3p 
                 7.49 
                 8.70 
                 12.82 
                 13.42 
                 0.04 
                 0.09 
                 1.54 
                 1.77 
                 1.21 
                 4.12 
                 0.60 
                 5.93 
               
               
                   
                 92b 
               
               
                 hsa-miR-1975 
                 hsa-mir- 
                 3p 
                 11.08 
                 13.22 
                 13.55 
                 14.01 
                 0.48 
                 2.09 
                 2.56 
                 2.67 
                 2.13 
                 0.34 
                 0.46 
                 2.93 
               
               
                   
                 1975 
               
               
                 hsa-miR-99a 
                 hsa-mir- 
                 5p 
                 9.77 
                 11.19 
                 11.96 
                 12.65 
                 0.19 
                 0.52 
                 0.85 
                 1.03 
                 1.43 
                 0.77 
                 0.69 
                 2.88 
               
               
                   
                 99a 
               
               
                 hsa-miR-191 
                 hsa-mir- 
                 5p 
                 14.67 
                 15.57 
                 16.40 
                 16.82 
                 5.71 
                 10.68 
                 18.46 
                 18.69 
                 0.90 
                 0.84 
                 0.42 
                 2.15 
               
               
                   
                 191 
               
               
                 hsa-miR-378 
                 hsa-mir- 
                 3p 
                 10.37 
                 12.53 
                 12.26 
                 11.87 
                 0.29 
                 1.30 
                 1.04 
                 0.61 
                 2.15 
                 −0.26 
                 −0.39 
                 1.50 
               
               
                   
                 378 
               
               
                 hsa-miR-23b 
                 hsa-mir- 
                 3p 
                 14.06 
                 15.35 
                 15.18 
                 15.35 
                 3.73 
                 9.19 
                 7.92 
                 6.72 
                 1.30 
                 −0.17 
                 0.16 
                 1.29 
               
               
                   
                 23b 
               
               
                 hsa-miR- 
                 hsa-mir- 
                 5p 
                 12.92 
                 13.55 
                 13.29 
                 14.08 
                 1.69 
                 2.64 
                 2.13 
                 2.79 
                 0.64 
                 −0.27 
                 0.79 
                 1.16 
               
               
                 125a-5p 
                 125a 
               
               
                 hsa-miR-203 
                 hsa-mir- 
                 3p 
                 13.49 
                 13.60 
                 13.39 
                 14.57 
                 2.53 
                 2.73 
                 2.29 
                 3.92 
                 0.11 
                 −0.21 
                 1.18 
                 1.08 
               
               
                   
                 203 
               
               
                 hsa-miR-205 
                 hsa-mir- 
                 5p 
                 14.61 
                 15.23 
                 14.11 
                 14.55 
                 5.48 
                 8.43 
                 3.76 
                 3.87 
                 0.62 
                 −1.12 
                 0.44 
                 −0.06 
               
               
                   
                 205 
               
               
                 hsa-miR-31 
                 hsa-mir-31 
                 5p 
                 13.69 
                 13.31 
                 12.40 
                 12.74 
                 2.89 
                 2.24 
                 1.15 
                 1.10 
                 −0.37 
                 −0.91 
                 0.34 
                 −0.95 
               
               
                 hsa-miR-21 
                 hsa-mir-21 
                 5p 
                 16.40 
                 15.66 
                 14.50 
                 15.24 
                 19.01 
                 11.41 
                 4.94 
                 6.26 
                 −0.74 
                 −1.16 
                 0.74 
                 −1.16 
               
               
                 hsa-miR-17 
                 hsa-mir-17 
                 5p 
                 12.85 
                 12.68 
                 11.81 
                 11.61 
                 1.61 
                 1.44 
                 0.76 
                 0.50 
                 −0.17 
                 −0.87 
                 −0.20 
                 −1.24 
               
               
                 hsa-miR-29a 
                 hsa-mir- 
                 3p 
                 16.24 
                 14.90 
                 14.79 
                 14.81 
                 17.01 
                 6.72 
                 6.02 
                 4.64 
                 −1.34 
                 −0.11 
                 0.02 
                 −1.43 
               
               
                   
                 29a 
               
               
                 hsa-miR-193b 
                 hsa-mir- 
                 3p 
                 13.26 
                 12.09 
                 11.19 
                 11.67 
                 2.16 
                 0.96 
                 0.50 
                 0.52 
                 −1.17 
                 −0.90 
                 0.48 
                 −1.60 
               
               
                   
                 193b 
               
               
                 hsa-miR-31* 
                 hsa-mir-31 
                 3p 
                 13.56 
                 12.91 
                 11.60 
                 11.83 
                 2.64 
                 1.69 
                 0.66 
                 0.59 
                 −0.65 
                 −1.31 
                 0.24 
                 −1.73 
               
               
                 hsa-miR-210 
                 hsa-mir- 
                 3p 
                 12.29 
                 11.33 
                 10.60 
                 10.49 
                 1.10 
                 0.57 
                 0.33 
                 0.23 
                 −0.96 
                 −0.74 
                 −0.10 
                 −1.80 
               
               
                   
                 210 
               
               
                 hsa-miR-130a 
                 hsa-mir- 
                 3p 
                 13.91 
                 12.51 
                 12.71 
                 11.98 
                 3.38 
                 1.28 
                 1.42 
                 0.65 
                 −1.40 
                 0.19 
                 −0.73 
                 −1.94 
               
               
                   
                 130a 
               
               
                   
               
             
          
         
       
     
     The inventors then used the Agilent miRNA chips to investigate the repertoire of expression of the miRNAs of the human airway epithelium and compare the results obtained in high-throughput sequencing with those obtained with Agilent® commercial miRNA chips. Using this technique, 48 miRNAs were found to be significantly expressed and modulated (Log 2 of the level of intensity of expression&gt;8; 1&lt;log 2 (ratio)&lt;−1 and an adjusted P value&lt;0.05) in at least one of the four stages of differentiation (see  FIG. 3  and Table V). 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE V 
               
             
             
               
                   
               
               
                 miRNAs significantly expressed and modulated 
               
               
                 during differentiation of the airway epithelium 
               
               
                 identified by Agilent ® miRNA chips 
               
             
          
           
               
                   
                   
                 Modulation (ratio of the 
               
               
                   
                   
                 level of intensity of 
               
               
                   
                 Level of intensity of 
                 expression in log2 at two 
               
               
                   
                 expression in log2 
                 stages of differentiation) 
               
             
          
           
               
                 Name 
                 D0 
                 D7 
                 FC 
                 WD 
                 D7 − D0 
                 FC − D7 
                 WD − FC 
                 WD − D0 
               
               
                   
               
             
          
           
               
                 hsa-miR-449a 
                 1.47 
                 8.00 
                 13.70 
                 13.54 
                 6.53 
                 5.70 
                 −0.15 
                 12.08 
               
               
                 hsa-miR-449b 
                 0.47 
                 3.08 
                 9.33 
                 9.11 
                 2.61 
                 6.25 
                 −0.22 
                 8.64 
               
               
                 hsa-miR-34b 
                 0.77 
                 3.65 
                 8.13 
                 8.94 
                 2.88 
                 4.48 
                 0.81 
                 8.17 
               
               
                 hsa-miR-34c-5p 
                 3.94 
                 6.29 
                 10.56 
                 11.39 
                 2.35 
                 4.27 
                 0.82 
                 7.44 
               
               
                 hsa-miR-34b* 
                 5.96 
                 7.98 
                 11.35 
                 12.44 
                 2.02 
                 3.36 
                 1.10 
                 6.48 
               
               
                 hsa-miR-99a 
                 5.02 
                 7.35 
                 8.12 
                 8.31 
                 2.33 
                 0.77 
                 0.19 
                 3.28 
               
               
                 hsa-miR-30b 
                 7.62 
                 9.98 
                 10.03 
                 10.17 
                 2.36 
                 0.05 
                 0.15 
                 2.55 
               
               
                 hsa-miR-768-3p 
                 7.43 
                 9.51 
                 9.81 
                 9.96 
                 2.08 
                 0.30 
                 0.14 
                 2.53 
               
               
                 hsa-miR-30e 
                 6.73 
                 9.50 
                 9.25 
                 9.12 
                 2.76 
                 −0.25 
                 −0.13 
                 2.38 
               
               
                 hsa-miR-200a 
                 8.64 
                 10.58 
                 10.79 
                 10.84 
                 1.94 
                 0.20 
                 0.06 
                 2.20 
               
               
                 hsa-miR-26a 
                 8.50 
                 10.70 
                 10.59 
                 10.65 
                 2.20 
                 −0.11 
                 0.06 
                 2.15 
               
               
                 hsa-miR-200b 
                 9.93 
                 11.94 
                 11.87 
                 12.04 
                 2.01 
                 −0.07 
                 0.17 
                 2.11 
               
               
                 hsa-miR-429 
                 7.97 
                 9.68 
                 9.82 
                 9.93 
                 1.71 
                 0.14 
                 0.10 
                 1.95 
               
               
                 hsa-miR-34a 
                 8.58 
                 10.89 
                 10.35 
                 10.49 
                 2.31 
                 −0.54 
                 0.13 
                 1.91 
               
               
                 hsa-miR-141 
                 11.15 
                 13.31 
                 13.03 
                 13.03 
                 2.16 
                 −0.28 
                 0.00 
                 1.88 
               
               
                 hsa-miR-15a 
                 7.74 
                 10.10 
                 9.71 
                 9.61 
                 2.36 
                 −0.39 
                 −0.10 
                 1.87 
               
               
                 hsa-miR-30d 
                 7.06 
                 8.94 
                 8.88 
                 8.92 
                 1.88 
                 −0.06 
                 0.05 
                 1.86 
               
               
                 hsa-miR-23b 
                 8.92 
                 10.88 
                 10.61 
                 10.64 
                 1.96 
                 −0.27 
                 0.04 
                 1.72 
               
               
                 hsa-miR-224 
                 6.84 
                 9.40 
                 8.52 
                 8.52 
                 2.55 
                 −0.87 
                 0.00 
                 1.68 
               
               
                 hsa-miR-26b 
                 7.97 
                 9.91 
                 9.54 
                 9.62 
                 1.94 
                 −0.37 
                 0.08 
                 1.65 
               
               
                 hsa-miR-148a 
                 7.35 
                 9.41 
                 8.91 
                 8.95 
                 2.06 
                 −0.50 
                 0.04 
                 1.60 
               
               
                 hsa-miR-16 
                 9.47 
                 11.54 
                 11.18 
                 11.06 
                 2.07 
                 −0.36 
                 −0.11 
                 1.59 
               
               
                 hsa-miR-29c 
                 9.04 
                 10.66 
                 10.38 
                 10.62 
                 1.61 
                 −0.28 
                 0.24 
                 1.57 
               
               
                 hsa-miR-425 
                 6.61 
                 8.21 
                 8.39 
                 8.18 
                 1.59 
                 0.19 
                 −0.21 
                 1.57 
               
               
                 hsa-miR-30c 
                 7.80 
                 9.77 
                 9.43 
                 9.31 
                 1.97 
                 −0.34 
                 −0.12 
                 1.51 
               
               
                 hsa-let-7g 
                 9.30 
                 11.12 
                 10.59 
                 10.80 
                 1.83 
                 −0.54 
                 0.21 
                 1.50 
               
               
                 hsa-miR-151-5p 
                 6.71 
                 8.54 
                 8.17 
                 8.17 
                 1.83 
                 −0.37 
                 0.00 
                 1.46 
               
               
                 hsa-miR-200c 
                 10.20 
                 12.01 
                 11.54 
                 11.64 
                 1.82 
                 −0.47 
                 0.09 
                 1.44 
               
               
                 hsa-miR-27b 
                 9.26 
                 11.03 
                 10.57 
                 10.62 
                 1.77 
                 −0.47 
                 0.05 
                 1.36 
               
               
                 hsa-let-7f 
                 11.11 
                 12.75 
                 12.01 
                 12.19 
                 1.63 
                 −0.73 
                 0.17 
                 1.08 
               
               
                 hsa-let-7c 
                 9.10 
                 10.71 
                 10.00 
                 10.15 
                 1.61 
                 −0.71 
                 0.14 
                 1.05 
               
               
                 hsa-let-7a 
                 11.54 
                 13.16 
                 12.47 
                 12.55 
                 1.62 
                 −0.69 
                 0.08 
                 1.01 
               
               
                 hsa-let-7b 
                 11.00 
                 12.66 
                 11.89 
                 11.96 
                 1.67 
                 −0.77 
                 0.07 
                 0.97 
               
               
                 hsa-let-7e 
                 8.53 
                 9.91 
                 9.34 
                 9.48 
                 1.38 
                 −0.57 
                 0.15 
                 0.95 
               
               
                 hsa-miR-21 
                 14.27 
                 15.83 
                 15.15 
                 15.20 
                 1.56 
                 −0.69 
                 0.06 
                 0.93 
               
               
                 hsa-miR-374a 
                 7.04 
                 8.45 
                 7.91 
                 7.83 
                 1.41 
                 −0.54 
                 −0.08 
                 0.79 
               
               
                 hsa-miR-125a-5p 
                 7.37 
                 8.66 
                 8.20 
                 8.15 
                 1.29 
                 −0.46 
                 −0.04 
                 0.79 
               
               
                 hsa-miR-939 
                 6.64 
                 8.04 
                 7.41 
                 7.34 
                 1.40 
                 −0.63 
                 −0.07 
                 0.70 
               
               
                 hsa-miR-106b 
                 8.08 
                 9.47 
                 8.94 
                 8.77 
                 1.39 
                 −0.53 
                 −0.18 
                 0.69 
               
               
                 hsa-miR-25 
                 7.15 
                 8.50 
                 7.85 
                 7.80 
                 1.35 
                 −0.65 
                 −0.05 
                 0.66 
               
               
                 hsa-miR-96 
                 8.52 
                 9.71 
                 9.21 
                 9.16 
                 1.19 
                 −0.50 
                 −0.04 
                 0.64 
               
               
                 hsa-miR-22 
                 10.67 
                 11.75 
                 11.10 
                 11.15 
                 1.09 
                 −0.66 
                 0.05 
                 0.48 
               
               
                 hsa-miR-181a 
                 7.05 
                 8.47 
                 7.62 
                 7.25 
                 1.41 
                 −0.84 
                 −0.37 
                 0.20 
               
               
                 hsa-miR-21* 
                 7.28 
                 8.49 
                 7.75 
                 7.46 
                 1.21 
                 −0.74 
                 −0.29 
                 0.18 
               
               
                 hsa-miR-365 
                 8.44 
                 8.41 
                 7.21 
                 7.25 
                 −0.02 
                 −1.21 
                 0.05 
                 −1.18 
               
               
                 hsa-miR-130a 
                 8.83 
                 9.48 
                 7.95 
                 7.52 
                 0.65 
                 −1.53 
                 −0.43 
                 −1.31 
               
               
                 hsa-miR-100 
                 8.00 
                 7.55 
                 6.29 
                 6.52 
                 −0.46 
                 −1.25 
                 0.22 
                 −1.49 
               
               
                 hsa-miR-193b 
                 8.62 
                 7.95 
                 6.76 
                 6.69 
                 −0.67 
                 −1.19 
                 −0.07 
                 −1.93 
               
               
                   
               
             
          
         
       
     
     On comparing the miRNAs that are found to be significantly modulated and expressed in at least one condition of cellular culture in high-throughput sequencing of miRNAs (HTS) or in Agilent® miRNA chips, a strong correlation is obtained between the results obtained with the two techniques, with a correlation coefficient r=0.9106 (see  FIG. 4 ). 
     To summarize, 26 miRNAs were detected and selected in HTS in at least one of the culture conditions (with an abundance of expression above 1%) and 48 miRNAs on Agilent® miRNA chips (with a level of intensity of expression in log 2 above 8). Counting the common miRNAs obtained by the two techniques, this means 61 separate miRNAs significantly expressed in at least one of the conditions of differentiation of the epithelium (60 are shown in Table VI, to which hsa-miR-1975 must be added, see Table III). 
     The 22 miRNAs identified as significantly regulated and sufficiently abundant in HTS are also found to be modulated on Agilent® miRNA chips with varying significance and with various levels of intensity. 
     As described above, the miRNAs are synthesized in the form of precursors having a hairpin structure and then undergo a final maturation by the enzyme Dicer to give two small single-stranded RNAs (5p and 3p) of which one of the two strands called mature will interact with the RISC complex and exert its modulating function whereas the other complementary strand called star (designated mir-xy*) will be degraded. Accordingly, the inventors measured the two strands of each of the miRNAs systematically by means of the various techniques used (miRNA chips, sequencing, PCR). The inventors observed that for some of the miRNAs selected, the two strands (5p and 3p) are modulated, but only one of the two strands for a given selected miRNA is found to be expressed more abundantly. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE VI 
               
             
             
               
                   
               
               
                 Comparison of the miRNAs modulated and expressed between Agilent ® miRNA chips and HTS 
               
             
          
           
               
                   
                 Modulation (ratio of 
                 Modulation (ratio of 
                   
                   
               
               
                   
                 the level of intensity 
                 the level of intensity 
               
               
                   
                 of expression in log2 
                 of expression in log2 
               
               
                   
                 in two stages of 
                 in two stages of 
               
               
                   
                 differentiation) 
                 differentiation) 
                 Level of intensity of 
                 Level of intensity of 
               
               
                   
                 measured with the 
                 measured by high- 
                 expression in log2 
                 expression in log2 
               
               
                   
                 Agilent chips 
                 throughput sequencing 
                 measured with the 
                 measured by high- 
               
             
          
           
               
                   
                 D7 − 
                 FC − 
                 WD − 
                   
                 D7 − 
                 FC − 
                 WD − 
                   
                 Agilent chips 
                 throughput sequencing 
               
             
          
           
               
                 Name 
                 D0 
                 D7 
                 FC 
                 WD − D0 
                 D0 
                 D7 
                 FC 
                 WD − D0 
                 D0 
                 D7 
                 FC 
                 WD 
                 D0 
                 D7 
                 FC 
                 WD 
               
               
                   
               
             
          
           
               
                 hsa-let-7a 
                 1.62 
                 −0.69 
                 0.08 
                 1.01 
                 −0.64 
                 0.28 
                 0.88 
                 0.51 
                 11.54 
                 13.16 
                 12.47 
                 12.55 
                 3.80 
                 3.16 
                 3.43 
                 4.31 
               
               
                 hsa-let-7b 
                 1.67 
                 −0.77 
                 0.07 
                 0.97 
                 −0.57 
                 −0.03 
                 0.66 
                 0.05 
                 11.00 
                 12.66 
                 11.89 
                 11.96 
                 11.23 
                 10.65 
                 10.62 
                 11.28 
               
               
                 hsa-let-7c 
                 1.61 
                 −0.71 
                 0.14 
                 1.05 
                 0.14 
                 0.21 
                 0.55 
                 0.90 
                 9.10 
                 10.71 
                 10.00 
                 10.15 
                 6.96 
                 7.10 
                 7.31 
                 7.86 
               
               
                 hsa-let-7e 
                 1.38 
                 −0.57 
                 0.15 
                 0.95 
                 0.38 
                 −0.27 
                 0.07 
                 0.18 
                 8.53 
                 9.91 
                 9.34 
                 9.48 
                 7.42 
                 7.80 
                 7.53 
                 7.60 
               
               
                 hsa-let-7f 
                 1.63 
                 −0.73 
                 0.17 
                 1.08 
                 0.22 
                 −0.56 
                 0.45 
                 0.11 
                 11.11 
                 12.75 
                 12.01 
                 12.19 
                 5.24 
                 5.46 
                 4.90 
                 5.35 
               
               
                 hsa-let-7g 
                 1.83 
                 −0.54 
                 0.21 
                 1.50 
                 −0.24 
                 −0.03 
                 0.83 
                 0.56 
                 9.30 
                 11.12 
                 10.59 
                 10.80 
                 11.84 
                 11.60 
                 11.57 
                 12.40 
               
               
                 hsa-miR-100 
                 −0.46 
                 −1.25 
                 0.22 
                 −1.49 
                 −1.05 
                 −2.36 
                 1.69 
                 −1.72 
                 8.00 
                 7.55 
                 6.29 
                 6.52 
                 10.72 
                 9.67 
                 7.32 
                 9.00 
               
               
                 hsa-miR-106b 
                 1.39 
                 −0.53 
                 −0.18 
                 0.69 
                 1.33 
                 −0.28 
                 −0.09 
                 0.96 
                 8.08 
                 9.47 
                 8.94 
                 8.77 
                 4.43 
                 5.76 
                 5.48 
                 5.39 
               
               
                 hsa-miR- 
                 1.29 
                 −0.46 
                 −0.04 
                 0.79 
                 0.64 
                 −0.27 
                 0.79 
                 1.16 
                 7.37 
                 8.66 
                 8.20 
                 8.15 
                 12.92 
                 13.55 
                 13.29 
                 14.08 
               
               
                 125a-5p 
               
               
                 hsa-miR-130a 
                 0.65 
                 −1.53 
                 −0.43 
                 −1.31 
                 −1.40 
                 0.19 
                 −0.73 
                 −1.94 
                 8.83 
                 9.48 
                 7.95 
                 7.52 
                 13.91 
                 12.51 
                 12.71 
                 11.98 
               
               
                 hsa-miR- 
                 1.54 
                 −0.08 
                 0.06 
                 1.52 
                 0.33 
                 0.37 
                 0.04 
                 0.73 
                 3.55 
                 5.09 
                 5.01 
                 5.07 
                 12.39 
                 12.72 
                 13.08 
                 13.12 
               
               
                 140-3p 
               
               
                 hsa-miR-141 
                 2.16 
                 −0.28 
                 0.00 
                 1.88 
                 1.17 
                 0.37 
                 0.17 
                 1.70 
                 11.15 
                 13.31 
                 13.03 
                 13.03 
                 8.05 
                 9.22 
                 9.58 
                 9.75 
               
               
                 hsa-miR-148a 
                 2.06 
                 −0.50 
                 0.04 
                 1.60 
                 1.31 
                 −0.28 
                 0.91 
                 1.93 
                 7.35 
                 9.41 
                 8.91 
                 8.95 
                 7.04 
                 8.34 
                 8.06 
                 8.97 
               
               
                 hsa-miR- 
                 1.83 
                 −0.37 
                 0.00 
                 1.46 
                 1.13 
                 −0.02 
                 −0.09 
                 1.02 
                 6.71 
                 8.54 
                 8.17 
                 8.17 
                 9.20 
                 10.33 
                 10.31 
                 10.22 
               
               
                 151-5p 
               
               
                 hsa-miR-15a 
                 2.36 
                 −0.39 
                 −0.10 
                 1.87 
                 1.41 
                 −0.19 
                 0.35 
                 1.57 
                 7.74 
                 10.10 
                 9.71 
                 9.61 
                 6.11 
                 7.52 
                 7.33 
                 7.68 
               
               
                 hsa-miR-16 
                 2.07 
                 −0.36 
                 −0.11 
                 1.59 
                 2.01 
                 −1.17 
                 1.38 
                 2.22 
                 9.47 
                 11.54 
                 11.18 
                 11.06 
                 3.13 
                 5.14 
                 3.97 
                 5.35 
               
               
                 hsa-miR-17 
                 0.31 
                 −1.14 
                 −0.39 
                 −1.22 
                 −0.17 
                 −0.87 
                 −0.20 
                 −1.24 
                 9.03 
                 9.34 
                 8.19 
                 7.81 
                 12.85 
                 12.68 
                 11.81 
                 11.61 
               
               
                 hsa-miR-181a 
                 1.41 
                 −0.84 
                 −0.37 
                 0.20 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 7.05 
                 8.47 
                 7.62 
                 7.25 
                 0.01 
                 0.01 
                 0.01 
                 0.01 
               
               
                 hsa-miR-191 
                 2.32 
                 0.29 
                 −0.30 
                 2.31 
                 0.90 
                 0.84 
                 0.42 
                 2.15 
                 0.64 
                 2.97 
                 3.25 
                 2.95 
                 14.67 
                 15.57 
                 16.40 
                 16.82 
               
               
                 hsa-miR-193b 
                 −0.67 
                 −1.19 
                 −0.07 
                 −1.93 
                 −1.17 
                 −0.90 
                 0.48 
                 −1.60 
                 8.62 
                 7.95 
                 6.76 
                 6.69 
                 13.26 
                 12.09 
                 11.19 
                 11.67 
               
               
                 hsa-miR-200a 
                 1.94 
                 0.20 
                 0.06 
                 2.20 
                 1.00 
                 0.67 
                 0.54 
                 2.20 
                 8.64 
                 10.58 
                 10.79 
                 10.84 
                 9.02 
                 10.01 
                 10.68 
                 11.22 
               
               
                 hsa-miR-200b 
                 2.01 
                 −0.07 
                 0.17 
                 2.11 
                 0.76 
                 0.56 
                 1.03 
                 2.36 
                 9.93 
                 11.94 
                 11.87 
                 12.04 
                 8.60 
                 9.37 
                 9.93 
                 10.96 
               
               
                 hsa-miR-200c 
                 1.82 
                 −0.47 
                 0.09 
                 1.44 
                 0.78 
                 0.46 
                 1.05 
                 2.29 
                 10.20 
                 12.01 
                 11.54 
                 11.64 
                 8.35 
                 9.13 
                 9.59 
                 10.64 
               
               
                 hsa-miR-203 
                 0.97 
                 −0.67 
                 0.13 
                 0.44 
                 0.11 
                 −0.21 
                 1.18 
                 1.08 
                 10.64 
                 11.61 
                 10.95 
                 11.08 
                 13.50 
                 13.60 
                 13.39 
                 14.57 
               
               
                 hsa-miR-205 
                 1.00 
                 −0.72 
                 −0.39 
                 −0.11 
                 0.62 
                 −1.12 
                 0.44 
                 −0.06 
                 13.18 
                 14.18 
                 13.46 
                 13.07 
                 14.61 
                 15.23 
                 14.11 
                 14.55 
               
               
                 hsa-miR-21 
                 1.56 
                 −0.69 
                 0.06 
                 0.93 
                 −0.74 
                 −1.16 
                 0.74 
                 −1.16 
                 14.27 
                 15.83 
                 15.15 
                 15.20 
                 16.40 
                 15.66 
                 14.50 
                 15.24 
               
               
                 hsa-miR-21* 
                 1.21 
                 −0.74 
                 −0.29 
                 0.18 
                 0.44 
                 −0.62 
                 −0.07 
                 −0.25 
                 7.28 
                 8.49 
                 7.75 
                 7.46 
                 8.34 
                 8.78 
                 8.16 
                 8.09 
               
               
                 hsa-miR-210 
                 0.18 
                 −0.63 
                 −0.11 
                 −0.56 
                 −0.96 
                 −0.74 
                 −0.10 
                 −1.80 
                 9.08 
                 9.25 
                 8.63 
                 8.52 
                 12.29 
                 11.33 
                 10.60 
                 10.49 
               
               
                 hsa-miR-22 
                 1.09 
                 −0.66 
                 0.05 
                 0.48 
                 0.80 
                 −1.14 
                 0.73 
                 0.40 
                 10.67 
                 11.75 
                 11.10 
                 11.15 
                 8.89 
                 9.69 
                 8.55 
                 9.29 
               
               
                 hsa-miR-224 
                 2.55 
                 −0.87 
                 0.00 
                 1.68 
                 1.52 
                 −0.72 
                 0.83 
                 1.63 
                 6.84 
                 9.40 
                 8.52 
                 8.52 
                 9.59 
                 11.12 
                 10.39 
                 11.22 
               
               
                 hsa-miR-23a 
                 0.78 
                 −0.94 
                 0.02 
                 −0.14 
                 0.06 
                 −0.80 
                 0.43 
                 −0.31 
                 11.72 
                 12.50 
                 11.56 
                 11.58 
                 14.42 
                 14.47 
                 13.67 
                 14.10 
               
               
                 hsa-miR-23b 
                 1.96 
                 −0.27 
                 0.04 
                 1.72 
                 1.30 
                 −0.17 
                 0.16 
                 1.29 
                 8.92 
                 10.88 
                 10.61 
                 10.64 
                 14.06 
                 15.35 
                 15.18 
                 15.35 
               
               
                 hsa-miR-25 
                 1.35 
                 −0.65 
                 −0.05 
                 0.66 
                 0.66 
                 −0.03 
                 −0.39 
                 0.24 
                 7.15 
                 8.50 
                 7.85 
                 7.80 
                 9.11 
                 9.77 
                 9.74 
                 9.35 
               
               
                 hsa-miR-26a 
                 2.20 
                 −0.11 
                 0.06 
                 2.15 
                 1.31 
                 −0.98 
                 2.90 
                 3.22 
                 8.50 
                 10.70 
                 10.59 
                 10.65 
                 0.30 
                 1.61 
                 0.62 
                 3.52 
               
               
                 hsa-miR-26b 
                 1.94 
                 −0.37 
                 0.08 
                 1.65 
                 0.09 
                 0.05 
                 0.78 
                 0.92 
                 7.97 
                 9.91 
                 9.54 
                 9.62 
                 6.84 
                 6.93 
                 6.97 
                 7.75 
               
               
                 hsa-miR-27b 
                 1.77 
                 −0.47 
                 0.05 
                 1.36 
                 0.64 
                 −0.69 
                 −0.06 
                 −0.11 
                 9.26 
                 11.03 
                 10.57 
                 10.62 
                 6.92 
                 7.57 
                 6.88 
                 6.81 
               
               
                 hsa-miR-29a 
                 0.17 
                 −0.71 
                 0.16 
                 −0.38 
                 −1.34 
                 −0.11 
                 0.02 
                 −1.43 
                 11.23 
                 11.40 
                 10.69 
                 10.85 
                 16.24 
                 14.90 
                 14.79 
                 14.81 
               
               
                 hsa-miR-29c 
                 1.61 
                 −0.28 
                 0.24 
                 1.57 
                 0.82 
                 0.02 
                 0.03 
                 0.87 
                 9.04 
                 10.66 
                 10.38 
                 10.62 
                 13.66 
                 14.48 
                 14.50 
                 14.53 
               
               
                 hsa-miR-30b 
                 2.36 
                 0.05 
                 0.15 
                 2.55 
                 0.83 
                 −0.27 
                 0.68 
                 1.24 
                 7.62 
                 9.98 
                 10.03 
                 10.17 
                 8.50 
                 9.33 
                 9.06 
                 9.74 
               
               
                 hsa-miR-30c 
                 1.97 
                 −0.34 
                 −0.12 
                 1.51 
                 0.32 
                 −0.33 
                 −0.39 
                 −0.40 
                 7.80 
                 9.77 
                 9.43 
                 9.31 
                 0.42 
                 0.73 
                 0.41 
                 0.01 
               
               
                 hsa-miR-30d 
                 1.88 
                 −0.06 
                 0.05 
                 1.86 
                 0.64 
                 −0.09 
                 1.20 
                 1.75 
                 7.06 
                 8.94 
                 8.88 
                 8.92 
                 9.12 
                 9.76 
                 9.67 
                 10.87 
               
               
                 hsa-miR-30e 
                 2.76 
                 −0.25 
                 −0.13 
                 2.38 
                 1.27 
                 −0.02 
                 0.46 
                 1.71 
                 6.73 
                 9.50 
                 9.25 
                 9.12 
                 7.04 
                 8.31 
                 8.30 
                 8.76 
               
               
                 hsa-miR-31 
                 0.77 
                 −1.16 
                 −0.15 
                 −0.54 
                 −0.37 
                 −0.91 
                 0.34 
                 −0.95 
                 10.13 
                 10.90 
                 9.74 
                 9.59 
                 13.69 
                 13.31 
                 12.40 
                 12.74 
               
               
                 hsa-miR-31* 
                 0.43 
                 −1.10 
                 −0.10 
                 −0.77 
                 −0.65 
                 −1.31 
                 0.24 
                 −1.73 
                 9.00 
                 9.42 
                 8.33 
                 8.22 
                 13.56 
                 12.91 
                 11.60 
                 11.83 
               
               
                 hsa-miR-34a 
                 2.31 
                 −0.54 
                 0.13 
                 1.91 
                 1.46 
                 −1.04 
                 0.45 
                 0.88 
                 8.58 
                 10.89 
                 10.35 
                 10.49 
                 10.31 
                 11.77 
                 10.73 
                 11.18 
               
               
                 hsa-miR-34b 
                 2.88 
                 4.48 
                 0.81 
                 8.17 
                 1.25 
                 4.17 
                 1.32 
                 6.74 
                 0.77 
                 3.65 
                 8.13 
                 8.94 
                 7.01 
                 8.26 
                 12.43 
                 13.75 
               
               
                 hsa-miR-34b* 
                 2.02 
                 3.36 
                 1.10 
                 6.48 
                 1.22 
                 3.50 
                 0.95 
                 5.67 
                 5.96 
                 7.98 
                 11.35 
                 12.44 
                 4.99 
                 6.20 
                 9.70 
                 10.65 
               
               
                 hsa-miR- 
                 2.35 
                 4.27 
                 0.82 
                 7.44 
                 1.33 
                 4.02 
                 1.06 
                 6.41 
                 3.94 
                 6.29 
                 10.56 
                 11.39 
                 7.88 
                 9.21 
                 13.23 
                 14.29 
               
               
                 34c-5p 
               
               
                 hsa-miR-365 
                 −0.02 
                 −1.21 
                 0.05 
                 −1.18 
                 −0.39 
                 0.00 
                 0.00 
                 −0.39 
                 8.44 
                 8.41 
                 7.21 
                 7.25 
                 0.41 
                 0.01 
                 0.01 
                 0.01 
               
               
                 hsa-miR-374a 
                 1.41 
                 −0.54 
                 −0.08 
                 0.79 
                 −0.33 
                 1.74 
                 0.74 
                 2.16 
                 7.04 
                 8.45 
                 7.91 
                 7.83 
                 0.62 
                 0.30 
                 2.04 
                 2.78 
               
               
                 hsa-miR-378 
                 3.23 
                 −0.81 
                 −0.26 
                 2.16 
                 2.15 
                 −0.26 
                 −0.39 
                 1.50 
                 4.38 
                 7.61 
                 6.80 
                 6.54 
                 10.37 
                 12.53 
                 12.26 
                 11.87 
               
               
                 hsa-miR-425 
                 1.59 
                 0.19 
                 −0.21 
                 1.57 
                 0.42 
                 0.74 
                 −0.04 
                 1.12 
                 6.61 
                 8.21 
                 8.39 
                 8.18 
                 10.58 
                 11.01 
                 11.75 
                 11.70 
               
               
                 hsa-miR-429 
                 1.71 
                 0.14 
                 0.10 
                 1.95 
                 0.42 
                 0.14 
                 0.74 
                 1.30 
                 7.97 
                 9.68 
                 9.82 
                 9.93 
                 8.23 
                 8.65 
                 8.79 
                 9.53 
               
               
                 hsa-miR-449a 
                 6.53 
                 5.70 
                 −0.15 
                 12.08 
                 5.21 
                 5.21 
                 0.21 
                 10.63 
                 1.47 
                 8.00 
                 13.70 
                 13.54 
                 4.48 
                 9.69 
                 14.90 
                 15.11 
               
               
                 hsa-miR-449b 
                 2.61 
                 6.25 
                 −0.22 
                 8.64 
                 3.32 
                 5.40 
                 −0.12 
                 8.60 
                 0.47 
                 3.08 
                 9.33 
                 9.11 
                 3.64 
                 6.96 
                 12.36 
                 12.24 
               
               
                 hsa-miR- 
                 1.69 
                 −0.46 
                 −0.18 
                 1.04 
                 0.48 
                 0.12 
                 0.32 
                 0.92 
                 4.73 
                 6.42 
                 5.96 
                 5.77 
                 13.64 
                 14.12 
                 14.24 
                 14.56 
               
               
                 574-3p 
               
               
                 hsa-miR-92b 
                 0.48 
                 4.21 
                 −0.29 
                 4.39 
                 1.21 
                 4.12 
                 0.60 
                 5.93 
                 0.10 
                 0.57 
                 4.78 
                 4.49 
                 7.49 
                 8.70 
                 12.82 
                 13.42 
               
               
                 hsa-miR-939 
                 1.40 
                 −0.63 
                 −0.07 
                 0.70 
                 0.13 
                 −0.13 
                 0.00 
                 0.00 
                 6.64 
                 8.04 
                 7.41 
                 7.34 
                 0.01 
                 0.15 
                 0.01 
                 0.01 
               
               
                 hsa-miR-96 
                 1.19 
                 −0.50 
                 −0.04 
                 0.64 
                 −0.08 
                 −0.71 
                 0.81 
                 0.02 
                 8.52 
                 9.71 
                 9.21 
                 9.16 
                 5.41 
                 5.33 
                 4.62 
                 5.43 
               
               
                 hsa-miR-99a 
                 2.33 
                 0.77 
                 0.19 
                 3.28 
                 1.43 
                 0.77 
                 0.69 
                 2.88 
                 5.02 
                 7.35 
                 8.12 
                 8.31 
                 9.77 
                 11.19 
                 11.96 
                 12.65 
               
               
                   
               
             
          
         
       
     
     It should be noted that mir-449a, mir-449b, mir-449b*, mir-34a, mir-34b (3p), mir-34b* (5p), mir-34c (5p) are found to be significantly modulated during differentiation and are therefore involved in initiating and maintaining the state of differentiation of the airway epithelium. 
     These five miRNAs: mir-449a, mir-449b, mir-34a, mir-34b, mir-34c are found to be strongly induced during differentiation, more particularly at the start of ciliogenesis. Once induced, their expression remains high and stable throughout differentiation including in the wholly differentiated epithelium. The completely differentiated repertoire of the miRNAs of the epithelium is characterized by a remarkable abundance of these 5 miRNAs which represent nearly 20% of the total number of all the miRNAs expressed in this tissue. Regarding mir-34a, however, it is induced less strongly than the other four miRNAs and is found earlier, at stage ALI-D7. 
     Interestingly, the 5p strands of each of the miRNAs mir-449a, mir-449b, mir-34a, mir-34b and mir-34c share a sequence homology at the level of their recognition sequence, suggesting that they target certain transcripts in common. 
     That is why the inventors then concentrated their efforts on these 5 miRNAs. The levels of regulation of these miRNAs as well as of mir-31 (which is found to be repressed during differentiation of the airway epithelium) were validated by a third approach, by quantitative PCR (see  FIG. 5 ). 
     These 5 miRNAs that are overexpressed during differentiation of the airway epithelium belong to two separate miRNA families: mir-449 and mir-34. Moreover, the genomic localization of mir-449a and of mir-449b is identical: both are localized at the level of the second intron of the cdc20b gene, situated on human chromosome 5 (5q11.2, chr5:54456388-54504760). The mir-34 family is composed of mir-34a which is localized in an intergenic region of chromosome 1 whereas the miRNAs mir-34b and mir-34c belong to the same cluster and both are localized in an intergenic region of chromosome 11. The mir-34 family has been linked functionally to the p53 signalling pathway. 
     II-2.B. Ciliated Epidermal Cells of  Xenopus  Embryos 
     The results obtained for this model are presented in Table IIIB below and in  FIG. 6 , which also presents results for the HAEC cells. 
     These tests show that, once again, the microRNA family miR-449, and more particularly miR-449a, constitute by far the microRNAs most strongly induced during ciliogenesis. 
     
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE IIIB 
               
             
             
               
                   
               
               
                 miRNAs significantly expressed in the ciliated cells of the 
               
               
                   Xenopus  embryo epidermis, comparison with non-ciliated cells 
               
             
          
           
               
                   
                 Log Ratio 
                   
                   
                   
                   
               
               
                   
                 of expression of 
                 % of miR 
                   
                   
                   
               
               
                   
                 miR between 
                 non- 
                 % of miR 
                   
                   
               
               
                 
                   xenopus 
                 
                 ciliated-non- 
                 ciliated 
                 ciliated 
                 sd non- 
                 sd 
               
               
                 miRNA 
                 ciliated 
                 cells 
                 cells 
                 ciliated 
                 ciliated 
               
               
                   
               
             
          
           
               
                 miR-449a 
                 3.166507029 
                 4.241910975 
                 38.99145137 
                 0.66831542 
                 0.5580561 
               
               
                 miR-17-5p 
                 1.843961214 
                 1.739241798 
                 6.439037664 
                 0.03088444 
                 0.44692614 
               
               
                 miR-427 
                 −3.577711451 
                 84.3912305 
                 7.287645762 
                 3.81200367 
                 0.43536764 
               
               
                 miR-18a 
                 1.963297831 
                 1.445998485 
                 5.770842336 
                 0.25353698 
                 0.40662557 
               
               
                 miR-203 
                 2.899525765 
                 0.802824596 
                 6.122022692 
                 0.14427702 
                 0.16748381 
               
               
                 miR-429 
                 3.489311848 
                 0.5611861 
                 6.308452174 
                 0.18811487 
                 0.19190601 
               
               
                 miR-34b 
                 8.639233391 
                 0.023309799 
                 6.678155706 
                 0.02362849 
                 0.24212636 
               
               
                 miR-130c 
                 3.303007088 
                 0.319262952 
                 3.090857721 
                 0.13938414 
                 0.20761583 
               
               
                 miR-20b 
                 0.920427989 
                 1.297427834 
                 1.839130412 
                 1.29177087 
                 0.55721948 
               
               
                 miR-200a 
                 2.92597595 
                 0.309242272 
                 2.418052837 
                 0.03713634 
                 0.23727106 
               
               
                 miR-130b 
                 5.041603605 
                 0.061086987 
                 2.057820515 
                 0.01136075 
                 0.16380899 
               
               
                 miR-106 
                 2.067406718 
                 0.395322902 
                 1.683867839 
                 0.09703348 
                 0.14099092 
               
               
                 miR-93b 
                 0.31478571 
                 0.797852579 
                 0.902730776 
                 0.63514139 
                 0.4494722 
               
               
                 miR-93a 
                 0.317106219 
                 0.795629375 
                 0.898232543 
                 0.63828547 
                 0.44663817 
               
               
                 miR-26 
                 2.754387045 
                 0.166267205 
                 1.158759618 
                 0.02096265 
                 0.18818027 
               
               
                 miR-20a 
                 2.428912948 
                 0.212684269 
                 1.096366145 
                 0.11342212 
                 0.12723715 
               
               
                 miR-218 
                 12.28452357 
                 0.002273204 
                 1.086641349 
                 0.00307337 
                 0.11041905 
               
               
                 miR-34a 
                 1.883909316 
                 0.183851237 
                 0.690835543 
                 0.04597169 
                 0.08895895 
               
               
                   
               
             
          
         
       
     
     II-2.C. Discussion 
     Whereas the miR-449s represent less than 0.01% of all the sequences of microRNAs in the HAEC cells during their multiplication, these miR-449s represent more than 8% of the microRNAs expressed in the differentiated HAEC cells (see  FIG. 6  graphs a and b). Moreover, miR-449a in the cells of  Xenopus  increases significantly during differentiation, representing up to 39% of all the sequences of microRNAs in ciliated cells of epidermal explants (see  FIG. 6 , graphs c-d). 
     As pointed out above, the miR-449s and the miR-34s belong to one and the same superfamily of microRNAs. Interestingly, it is noted that expression of the members of the miR-34 family was also induced during ciliogenesis in the two models (see  FIG. 6 , graphs a and b), even if to a lesser extent than that of the miR-449s. 
     The miR-449 family seems be conserved in vertebrates: investigation of the syntenic loci of Cdc20b (where the miR-449 cluster is located in humans and in the frog) revealed the existence of miR-449 in all the genomes of vertebrates fully or partially sequenced. 
     The differentiated HAEC cells and the ciliated cells of the epidermis of  Xenopus laevis  consist of a mixture of different cellular types, including basal cells, mucus-secreting cells and multiciliated cells. 
     Hybridization in situ on HAEC primary cultures (see micrographs a and c of  FIG. 7 ) and on human bronchial tissue (see micrographs e and g of  FIG. 7 ) revealed that the miR-449s were expressed in the multiciliated cylindrical cells but not in the basal cells (see micrograph a of  FIG. 7 ) or in the muc5AC-positive secretory cells (see micrograph e of  FIG. 7 ). 
     These results were confirmed by the tests of high-throughput sequencing on fractions enriched with cylindrical cells (mainly composed of multiciliated cells and some mucus-secreting cells) and with basal cells, derived from the epithelium of human respiratory passages. 
     Graph d in  FIG. 7  shows an enrichment of the miR-449s in the fraction of ciliated cells, whereas the expression of the miR-34s that is observed is more uniform and was observed in both types of cells. 
     Finally, hybridization in situ on the cells of  Xenopus  embryos revealed that expression of the miR-449s was restricted to the ciliated cells, said cells being positive on labeling with acetylated tubulin (see micrographs h and l of  FIG. 7 ). 
     All of these results show that the miR-449s are the most abundant microRNAs of the multiciliated cells of vertebrates. 
     III—Determination of the Specific Targets of the Selected miRNAs 
     III-1. Identification of the Specific Cellular Type of Each miRNA 
     Like the native airway epithelium, the model of differentiation in vitro used in these tests consists of basal cells, ciliated cells and mucus-secreting cells. In order to identify the repertoires of the miRNAs specific to each of the cellular types, the inventors used cell sorting by flow cytometry by means of specific markers (Hajj, R. et al. 2007). Using this technique, adult airway progenitor cells (corresponding a priori to basal cells) were isolated, selected and sorted (such cells appear doubly positive for tetraspanin CD151 and for the tissue factor) from the pyramidal cells (i.e. ciliated cells and mucus-secreting cells) which appear negative for these same markers. These were purified from polyps or from nasal conchae obtained from 3 separate donors. 
     After extracting the total RNAs, the expression profiles of the miRNAs were established by means of Agilent® commercial chips or by high-throughput sequencing (HTS). The two experimental approaches corroborate, for several miRNA selected including mir-449a, mir-449b, mir-34a, mir-34b, mir-34b* (mir-34b-5p), mir-34c and mir-34c* (mir-34c-3p), their specific expression in the epithelial ciliated cells. Moreover, this cell sorting experiment is able to show that the miRNAs repressed in cells in culture (e.g. mir-31, mir-31*, mir-205, mir-130a, mir-193b) are more specific to the basal cells (see  FIG. 8  and Table VII). For the first time, the inventors thus attribute a repertoire of expression of the miRNAs specifically to separate cellular types of the airway epithelium during differentiation. 
                                                         TABLE VII                   Specific miRNAs of the basal cells or of the pyramidal cells (ciliated +       secretory) identified by HTS and Agilent ® chips.                Modulation of   Intensity of   Intensity of           expression of the   the level of   the level of           miRNAs in pyramidal   expression   expression in           cells (323(−))   in log2 in   log2 in           relative to basal   basal cells   pyramidal       Name   cells 323(+)   (323(+))   cells (323(−))                    hsa-let-7a   −1.29   11.93   10.65       hsa-let-7b   −1.96   12.20   10.24       hsa-let-7c   −0.48   9.43   8.95       hsa-let-7e   −1.42   8.24   6.82       hsa-let-7f   −0.94   10.82   9.88       hsa-let-7g   −0.15   8.37   8.22       hsa-miR-100   1.62   3.28   4.90       hsa-miR-106b   −2.05   7.22   5.16       hsa-miR-125a-5p   −0.05   6.63   6.58       hsa-miR-130a   −6.33   9.76   3.43       hsa-miR-140-3p   0.91   2.75   3.66       hsa-miR-141   −2.88   11.12   8.24       hsa-miR-148a   −1.76   7.14   5.39       hsa-miR-151-5p   −0.73   7.24   6.51       hsa-miR-15a   −2.10   7.86   5.75       hsa-miR-16   −0.48   9.10   8.62       hsa-miR-17   −2.60   6.64   4.04       hsa-miR-181a   −2.29   6.88   4.59       hsa-miR-191   0.00   0.14   0.14       hsa-miR-193b   −3.57   3.90   0.33       hsa-miR-200a   −0.95   8.80   7.85       hsa-miR-200b   −0.15   9.99   9.84       hsa-miR-200c   −0.67   10.24   9.57       hsa-miR-203   −3.50   3.64   0.14       hsa-miR-205   −7.00   12.44   5.44       hsa-miR-21   −1.26   11.34   10.08       hsa-miR-21*   −2.20   5.03   2.83       hsa-miR-210   −2.03   6.60   4.57       hsa-miR-22   −1.73   8.81   7.07       hsa-miR-224   −2.84   3.65   0.82       hsa-miR-23a   −2.45   10.25   7.80       hsa-miR-23b   −2.23   9.41   7.18       hsa-miR-25   −0.70   5.40   4.70       hsa-miR-26a   −2.24   9.92   7.68       hsa-miR-26b   −1.47   8.75   7.28       hsa-miR-27b   −3.56   9.77   6.21       hsa-miR-29a   −2.95   11.09   8.14       hsa-miR-29c   −3.06   11.06   8.00       hsa-miR-30b   −0.80   8.76   7.96       hsa-miR-30c   −1.01   6.92   5.91       hsa-miR-30d   −1.11   8.16   7.05       hsa-miR-30e   −1.60   6.94   5.34       hsa-miR-31   −4.31   6.36   2.05       hsa-miR-31*   −3.70   3.84   0.14       hsa-miR-34a   0.64   6.72   7.36       hsa-miR-34b   8.24   0.88   9.12       hsa-miR-34b*   6.05   5.48   11.52       hsa-miR-34c-5p   5.74   4.75   10.49       hsa-miR-365   −0.99   4.83   3.84       hsa-miR-374a   −1.04   4.26   3.22       hsa-miR-378   −2.43   4.11   1.68       hsa-miR-425   0.70   4.52   5.22       hsa-miR-429   −0.31   6.92   6.61       hsa-miR-449a   6.07   2.81   8.88       hsa-miR-449b   4.05   0.14   4.18       hsa-miR-574-3p   0.91   3.53   4.44       hsa-miR-768-3p   −1.20   10.15   8.95       hsa-miR-92b   1.67   0.40   2.07       hsa-miR-939   1.28   4.81   6.08       hsa-miR-96   −1.51   6.81   5.30       hsa-miR-99a   0.99   5.42   6.40                    
III-2. Identification of the Target mRNAs of the miRNAs Selected
 
     A major challenge in miRNA biology is to be able to identify and characterize experimentally the target mRNAs that they regulate. With this objective, in silico approaches (bioinformatic software for predicting targets) were combined with experimental approaches (transcriptome chips, ectopic expression of miRNAs as well as of reporter vectors containing the 3′-UTR portion of the gene of interest fused to luciferase). Supplementary experiments used immunocytochemistry, video-microscopy and biochemistry approaches. 
     Several algorithms for predicting targets have been proposed. They are generally based on: i) the complementarity between the miRNA and the 3′UTR of the target mRNA in the 5′ region of the miRNA (recognition sequence); ii) phylogenetic conservation of this sequence in the 3′UTR of the target mRNA. 
     In order to determine the target genes potentially regulated by these miRNAs of interest, the inventors established profiling of the mRNAs by expression chip (Affymetrix, human HuGene 1.0 ST microarrays). The samples analyzed are the same as those used for measurement of the miRNAs during differentiation. A supplementary approach consisted of evaluating the transcriptome of airway epithelial cells after manipulation of the level of expression of the miRNAs selected by transfection. Target genes were selected in relation to regeneration and differentiation of the epithelium by means of bioinformatic aids (Mediante, Ingenuity Pathway™). The inventors were thus able to establish a functional link between the miRNAs previously identified and a certain number of transcripts implicated in the regeneration and differentiation of the human airway epithelium. The results obtained show that 500-1000 transcripts are associated with differentiation (see  FIG. 9 ). 
     Only the expression of some genes varies between ALI-FC and ALI-WD, indicating a stability of expression of the RNAs once ciliogenesis has been initiated. 
     III-3. Identification in Silico of the Putative Target Genes Common to the 5p Strands of the miRNAs mir-449a, mir-449b, mir-34a, mir-34b and mir-34c 
     The predicted target genes were recovered for each of the 5p strands of the 5 selected miRNAs mir-449a, mir-449b and mir-34a, mir-34b-5p (mir-34b*) and mir-34c-5p which share a sequence homology at the level of their recognition sequence, using predictive bioinformatic tools (i.e. TargetScan, mirbase target, picTar and Microcible 2 to 8) accessible via the Mediante network interface (www.microarray.fr). The inventors first selected the predicted target genes common to the 5 miRNAs of interest, which were validated by the methodology detailed above. Out of nearly 3500 predicted targets for each of the miRNAs taken separately, 1229 targets are common to the 5 miRNAs selected. The 1229 predicted targets were then compared with those significantly repressed (about 1000, P&lt;0.05) during differentiation more particularly between the wholly differentiated condition and the first step of undifferentiated proliferation (ALI-WD versus ALI-D0 (n=3 donors)). Thus, the results show 62 genes common to the 5 miRNAs selected that may play a key role in the regeneration of the airway epithelium (see Table VIII). Notably caveolin-1 is found among these genes. The results show that caveolin-1 is strongly inhibited throughout differentiation (see  FIG. 8 ). 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE VIII 
               
             
             
               
                   
               
               
                 Lists of putative target genes of the selected microRNAs found to 
               
               
                 be inhibited during differentiation of the airway epithelium. 
               
             
          
           
               
                   
                 Modulation of expression of 
                   
                   
                   
               
               
                   
                 the gene between the 
                 Amean 
                   
                 Accession 
               
               
                   
                 stages of differentiation 
                 (of 3 
                 Adjust. 
                 number of 
               
               
                 Gene 
                 WD and D0-ALI 
                 donors) 
                 P. Value 
                 the gene 
               
               
                   
               
             
          
           
               
                 ABLIM3 
                 −1.4481743 
                 7.524965 
                 3.82E−04 
                 NM_014945 
               
               
                 ADAM19 
                 −1.1163435 
                 6.14820233 
                 5.45E−07 
                 NM_033274 
               
               
                 ADAMTSL4 
                 −1.1186815 
                 7.2720022 
                 4.62E−04 
                 NM_019032 
               
               
                 ADCY7 
                 −1.382631 
                 7.6534838 
                 2.38E−07 
                 NM_001114 
               
               
                 AMOTL1 
                 −1.7460034 
                 8.6474232 
                 2.94E−06 
                 NM_130847 
               
               
                 ARPP-19 
                 −1.0941527 
                 8.8116738 
                 1.22E−05 
                 NM_006628 
               
               
                 BMP1 
                 −0.9680967 
                 8.6574928 
                 1.38E−05 
                 NM_001199 
               
               
                 BTBD11 
                 −1.8490199 
                 7.6618604 
                 1.14E−05 
                 NM_001018072 
               
               
                 C12orf29 
                 −1.2553972 
                 8.48381407 
                 1.68E−04 
                 NM_001009894 
               
               
                 CAV1 
                 −2.368023 
                 9.93025267 
                 4.53E−06 
                 NM_001753 
               
               
                 CDA 
                 −2.481947 
                 6.80947653 
                 2.94E−07 
                 NM_001785 
               
               
                 CDC25A 
                 −1.3080745 
                 6.28751913 
                 4.79E−06 
                 NM_001789 
               
               
                 CDCA5 
                 −1.0540303 
                 6.48987507 
                 1.09E−04 
                 NM_080668 
               
               
                 COL7A1 
                 −1.6867157 
                 8.59302327 
                 1.04E−06 
                 NM_000094 
               
               
                 CPM 
                 −1.4438189 
                 8.6954668 
                 9.13E−03 
                 NM_001005502 
               
               
                 CRABP2 
                 −1.4293157 
                 9.39830873 
                 6.87E−05 
                 NM_001878 
               
               
                 CTNNBIP1 
                 −1.0108869 
                 9.35766273 
                 2.86E−08 
                 NM_020248 
               
               
                 DKK1 
                 −2.5935028 
                 7.03329227 
                 4.98E−04 
                 NM_012242 
               
               
                 DLL1 
                 0.2733639 
                 7.4865392 
                   
                 NM_005618 
               
               
                 DSC3 
                 −1.3986191 
                 9.60600093 
                 5.07E−03 
                 NM_024423 
               
               
                 EFNA3 
                 −1.0526506 
                 7.54088253 
                 1.52E−03 
                 NM_004952 
               
               
                 EFNB1 
                 −1.6142037 
                 8.63543853 
                 1.49E−05 
                 NM_004429 
               
               
                 EMP1 
                 −3.521182 
                 8.67082233 
                 5.65E−04 
                 NM_001423 
               
               
                 FSTL3 
                 −1.617425 
                 8.44148553 
                 2.91E−06 
                 NM_005860 
               
               
                 FUT11 
                 −1.0545791 
                 8.3877732 
                 3.81E−04 
                 NM_173540 
               
               
                 GLTP 
                 −1.197381 
                 10.2894117 
                 5.63E−04 
                 NM_016433 
               
               
                 GPX3 
                 −1.483986 
                 8.54605007 
                 1.59E−04 
                 NM_002084 
               
               
                 IL1RN 
                 −2.7062559 
                 9.60439793 
                 2.04E−05 
                 NM_173841 
               
               
                 IQGAP3 
                 −1.1769401 
                 6.3339546 
                 1.56E−03 
                 NM_178229 
               
               
                 IRAK2 
                 −1.1324037 
                 7.05078867 
                 1.95E−04 
                 NM_001570 
               
               
                 ITPR2 
                 −1.1585075 
                 6.7519412 
                 9.93E−05 
                 NM_002223 
               
               
                 JAG1 
                 −0.8238893 
                 10.024193 
                   
                 NM_00214 
               
               
                 KDELR3 
                 −1.604097 
                 6.37016313 
                 1.74E−07 
                 NM_006855 
               
               
                 LYPD3 
                 −1.9136232 
                 9.53049673 
                 1.19E−03 
                 NM_014400 
               
               
                 MAP4K4 
                 −1.3458818 
                 9.26761513 
                 5.77E−07 
                 NM_145686 
               
               
                 MY05A 
                 −1.5881695 
                 7.809912 
                 3.04E−10 
                 NM_000259 
               
               
                 NDRG1 
                 −1.3955203 
                 11.7800207 
                 4.34E−03 
                 NM_006096 
               
               
                 NEDD4 
                 −1.8082366 
                 7.2788706 
                 7.67E−04 
                 NM_006154 
               
               
                 NOTCH1 
                 −0.5783195 
                 8.7229346 
                 0.0256397 
                 NM_017617 
               
               
                 PDLIM7 
                 −1.3596731 
                 8.12085653 
                 4.91E−06 
                 NM_005451 
               
               
                 PEA15 
                 −1.1301513 
                 9.77535027 
                 1.27E−03 
                 NM_003768 
               
               
                 PGAM4 
                 −1.1640039 
                 10.9063747 
                 6.86E−08 
                 NM_001029891 
               
               
                 PNPLA3 
                 −1.3599861 
                 6.92883227 
                 4.50E−06 
                 NM_025225 
               
               
                 PPL 
                 −1.1742775 
                 10.6121583 
                 1.74E−03 
                 NM_002705 
               
               
                 PRELID2 
                 −1.2843971 
                 6.360054 
                 2.69E−08 
                 NM_182960 
               
               
                 PRKCA 
                 −1.1283394 
                 6.67201333 
                 2.48E−04 
                 NM_002737 
               
               
                 RAET1L 
                 −2.9534389 
                 8.77895953 
                 1.67E−06 
                 NM_130900 
               
               
                 RIN1 
                 −1.23138 
                 7.72833807 
                 2.35E−06 
                 NM_004292 
               
               
                 SC5DL 
                 −1.1485737 
                 9.615791 
                 3.44E−06 
                 NM_006918 
               
               
                 SEMA4B 
                 −1.1518643 
                 9.4275898 
                 3.23E−05 
                 NM_198925 
               
               
                 SERPINB2 
                 −1.398391 
                 11.0805848 
                 8.01E−05 
                 NM_002575 
               
               
                 SERPINE1 
                 −2.945564 
                 9.083679 
                 1.16E−02 
                 NM_000602 
               
               
                 SLC37A2 
                 −1.5591718 
                 7.97890727 
                 2.68E−06 
                 NM_198277 
               
               
                 SLC4A7 
                 −1.5922747 
                 8.1975794 
                 8.73E−10 
                 NM_003615 
               
               
                 SPARC 
                 −2.1890128 
                 6.9962164 
                 3.28E−06 
                 NM_003118 
               
               
                 SYNC1 
                 −1.1653204 
                 6.9710348 
                 5.37E−05 
                 NM_030786 
               
               
                 TGFA 
                 −2.1820264 
                 8.82130713 
                 1.10E−07 
                 NM_003236 
               
               
                 TGFBI 
                 −1.3975298 
                 9.96521733 
                 1.62E−03 
                 NM_000358 
               
               
                 TGM2 
                 −2.4139445 
                 8.10195833 
                 7.22E−08 
                 NM_004613 
               
               
                 TMBIM1 
                 −1.2519402 
                 11.9735373 
                 2.56E−04 
                 NM_022152 
               
               
                 TMCC3 
                 −1.117217 
                 7.91308893 
                 1.99E−06 
                 NM_020698 
               
               
                 TMEFF1 
                 −1.3004997 
                 6.23670373 
                 3.30E−04 
                 NM_0JD03692 
               
               
                 TNS4 
                 −1.1104828 
                 9.96975587 
                 3.06E−06 
                 NM_032865 
               
               
                 UHRF2 
                 −1.1846124 
                 8.1264516 
                 1.95E−05 
                 NM_152896 
               
               
                 VAT1 
                 −1.2608379 
                 9.68055807 
                 6.22E−07 
                 NM_006373 
               
               
                 VSIG1 
                 −1.3975763 
                 4.822476 
                 6.93E−10 
                 NM_182607 
               
               
                 WNT4A 
                 0.9209719 
                 8.8476432 
                 0.0017319 
                 NM_030761 
               
               
                 WNT7A 
                 −2.0382706 
                 8.0121046 
                 1.19E−08 
                 NM_004625 
               
               
                   
               
             
          
         
       
     
     To this list of target genes of interest, we can add the genes Rfx2, Rfx3, FoxJ1 and STATH which are the targets predicted by bioinformatics of miR-31 and/or miR-130a. 
     IV—Validation of Caveolin-1 as Target of the miRNAs Selected 
     Caveolin-1 (Cav-1) is a membrane protein of 22 kDa essential for the formation of small invaginations of the plasma membrane called caveolae. The Cav-1 gene is expressed in the adherent cells (endothelial, epithelial, fibroblasts, smooth muscle cells). 
     More particularly, it has been shown that the caveolins are present on the membrane surface of the basal and ciliated epithelial cells, indicating a crucial role in these cellular types (Krasteva, G. et al. (2006)  Respir Res  7, 108). Loss of expression of caveolin-1 can lead to defective epithelial proliferation and differentiation (Yang, G. et al. (2008)  Exp Mol Pathol  84, 131-140). 
     Moreover, the caveolins have been implicated in various forms of susceptibility to respiratory diseases. For example, the caveolae contain a variety of receptors, and Cav-1 has been implicated in reduction of the number of receptors of transforming growth factor (TGF)-beta present on the cell surface. Earlier works emphasized the probable contribution of a deficiency of caveolin-1 in several respiratory diseases on account of disturbance of the TGF-beta pathway (Le Saux, C. J. et al. (2008)  J Biol Chem  283, 5760-5768). 
     Furthermore, it has been shown that several microorganisms utilize the caveolae selectively for infecting cells (Norkin, L. C. et al. (2001)  Exp Cell Res  266, 229-238). As these caveolae are localized on the basolateral surface of the ciliated cells of the airway epithelium, they might notably be involved in the endocytosis of infectious agents when there is an epithelial lesion (Krasteva, G. et al., 2006). In fact, the adenoviruses require a loss of integrity of the epithelium or of the tight junctions to gain access to the basolateral membrane of the ciliated cells in order to exert their pathogenic capacity (Walters, R. W. et al. (1999)  J Biol Chem  274, 10219-10226). Finally, the basal cells would be more vulnerable to infections (Pickles, R. J. et al. (1996)  Hum Gene Ther  7, 921-931 (1996). In agreement with this, it has been shown that the number of caveolae is greater for the basal cells than the ciliated cells (Krasteva, G. et al., 2006). 
     IV-1. Principle of the Tests 
     The MicroCible algorithm was used; it identifies 7 different sites of fixation for miR-34b-5p in the transcript of Cav-1, against 3 different sites of fixation for mir-34a/34c-5p, mir-449a/b. The inventors constructed an expression vector of a reporter gene in which the whole 3′-UTR portion of Cav-1 was inserted downstream of the luciferase coding sequence. Then, the HEK293T cells were co-transfected with this vector and each of the 5 miRNAs selected (mir34a/b-5p/c-5p/449a/b), independently in comparison with a negative control miRNA. 
     IV-2. Material and Methods 
     3′-UTR Expression Vectors and Measurement of Luciferase Activity 
     The complete sequence of the noncoding portion (3′-UTR) of caveolin (SEQ ID No. 178) is amplified by PCR and then cloned at the XhoI and NotI sites of the psiCheck2 vector (Promega). 
     The synthetic microRNAs of interest (miR-34a, miR-34b*, miR-34c-5p and the negative control miR (miR-Neg1)) were synthesized by the company Ambion (Applied Biosystems). Reverse transfection was performed on HEK293T cells (20000 cells per well) in a white 96-well plate with 100 ng of plasmid vector psiCheck2 and 5 nmol of synthetic miRNA using Lipofectamine 2000 (Invitrogen) as transfection agent. 48 hours after transfection, the activities of the luciferases renilla and firefly were evaluated with the Dual Glo Luciferase Assay System kit (Promega) and were measured by means of a luminometer (Luminoskan Ascent, Thermolab system). 
     Identification of Signalling Pathways 
     The software Ingenuity Pathway Analysis (IPA) (Ingenuity Systems, Mountain View, USA) was used for identifying networks of interaction between genes of interest and other functional groups. Genes having a ratio greater than 1 were selected. Thus, it is possible to associate biological functions and diseases with our experimental results. 
     IV-3. Results 
     The inventors showed that mir-34b-5p inhibited expression of the gene of luciferase significantly (P&lt;0.01) when the latter is fused to the noncoding 3′ portion of caveolin-1. These results, added to the fact that the inventors found caveolin-1 to be strongly inhibited during differentiation, indicate that Cav-1 is a specific target of mir-34b* (mir-34b-5p) involved in the process of differentiation of the airway epithelium ( FIG. 11 ). 
     It seems probable that the miRNAs, mir-449a, mir-449b, mir-34a and mir-34b*, not repressing caveolin-1, act on the regulation of one or more other genes. 
     According to the same principle, the test conducted with caveolin was reproduced with other target genes of interest; the 3′-UTR sequence of the following genes was cloned AREG (SEQ ID No. 179), AURKA (SEQ ID No. 180), CAPN13 (SEQ ID No. 181), CCNB1 (SEQ ID No. 182), CCNE2 (SEQ ID No. 183), CDC6 (SEQ ID No. 184), CDC25A (SEQ ID No. 185), CENPK (SEQ ID No. 186), CEP55 (SEQ ID No. 187), CDC20B (SEQ ID No. 188), E2F7 (SEQ ID No. 189), FOXM1 (SEQ ID No. 190), STATH (SEQ ID No. 191) and TOP2A (SEQ ID No. 192). 
     
       
         
               
             
               
               
               
               
             
           
               
                 TABLE IX 
               
             
             
               
                   
               
               
                 list of the target genes validated by at least one of the miRNAs selected 
               
             
          
           
               
                 Targets of miR-449a/b 
                   
                   
                 Targets 
               
               
                 or miR-34a, b, b*, c- 
                   
                 Accession 
                 validated for 
               
               
                 3p, c-5p tested 
                 Description of the 
                 number of 
                 at least one 
               
               
                 experimentally 
                 gene 
                 the gene 
                 of the miRNAs 
               
               
                   
               
               
                 AREG (SEQ ID No. 179) 
                 
                   Homo sapiens 
                 
                 NM_001657 
                 miR-449a/b and 
               
               
                   
                 amphiregulin (AREG), 
                   
                 miR-34a/c-5p 
               
               
                   
                 mRNA. 
                   
                   
               
               
                 AURKA (SEQ ID No. 180) 
                   Homo sapiens  aurora 
                 NM_198433 
                 miR-34b 
               
               
                   
                 kinase A (AURKA), 
                   
                   
               
               
                   
                 transcript variant 1, 
                   
                   
               
               
                   
                 mRNA. 
                   
                   
               
               
                 CCNB1 (SEQ ID No. 182) 
                   Homo sapiens  cyclin 
                 NM_031966 
                 miR-449a/b and 
               
               
                   
                 B1 (CCNB1), mRNA. 
                   
                 miR-34a/c-5p 
               
               
                 CCNE2 (SEQ ID No. 183) 
                   Homo sapiens  cyclin 
                 NM_057749 
                 miR-449a/b and 
               
               
                   
                 E2 (CCNE2), mRNA. 
                   
                 miR-34a/c-5p 
               
               
                 CDC25A (SEQ ID No. 185) 
                   Homo sapiens  cell 
                 NM_001789 
                 miR-449a/b and 
               
               
                   
                 division cycle 25 
                   
                 miR-34a/c-5p 
               
               
                   
                 homolog A ( S. pombe ) 
                   
                   
               
               
                   
                 (CDC25A), transcript 
                   
                   
               
               
                   
                 variant 1, mRNA. 
                   
                   
               
               
                 CEP55 (SEQ ID No. 187) 
                 
                   Homo sapiens 
                 
                 NM_018131 
                 miR-34b* 
               
               
                   
                 centrosomal protein 
                   
                   
               
               
                   
                 55 kDa (CEP55), 
                   
                   
               
               
                   
                 transcript variant 1, 
                   
                   
               
               
                   
                 mRNA. 
               
               
                   
               
             
          
         
       
     
     A target is validated if its expression is inhibited by a miRNA. 
     V—Identification by DNA Chips (Affymetrix®) of the Targets of the miRNAs of Interest: mir-449a, mir-449b, mir-34a, mir-34b*, mir-34c-5p 
     In order to determine the genes modulated specifically by the expression of a miRNA of interest, each miRNA, mir-449a, mir-449b, mir-34a, mir-34b* and mir-34c-5p, is transfected in primary cultures of undifferentiated airway epithelial cells (HAECs) and investigated by transcriptome chips (Affymetrix®), 48 h after transfection, for the genes that are differentially modulated. 
     Since mir-449a, mir-449b, mir-34a, mir-34b*, mir-34c-5p share the same “seed” (sequence 2-7), they are able to interact with common targets. Accordingly, 95 common genes were obtained as significantly modulated by these miRNAs. 
     Classically, it is assumed that a miRNA will act directly on its target mRNAs to repress their expression.  FIG. 12  shows the enrichment of target genes containing the complementary region of the recognition sequence of these miRNAs of interest in response to 48 h of transfection of each of these miRNAs. We observed, for the 95 modulated genes, that 41 genes are significantly repressed (see Table X). 
     Of these 41 repressed genes, 18 genes are predicted targets (by analysis in silico) common to the 5 miRNAs selected (see Table XI) and whose regulation by said miRNAs might play a key role in differentiation of the airway epithelium and in implementation of a therapeutic strategy for respiratory diseases (mucoviscidosis, asthma, chronic obstructive pulmonary diseases, primary ciliary dyskinesia etc.). 
     
       
         
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE IX 
               
             
             
               
                   
               
               
                 41 repressed genes common to the miRNAs mir-34a, mir-34b*, mir-34c-5p, mir-449a and mir-449b after 
               
               
                 transfection of each of the miRNAs of interest in HAECs. 
               
             
          
           
               
                   
                   
                   
                   
                 Modulation 
                   
                   
                   
               
               
                   
                   
                 Level of 
                 Modulation 
                 in the 
                 Modulation 
                 Modulation 
                 Modulation 
               
               
                   
                   
                 intensity of 
                 in the 
                 presence 
                 in the 
                 in the 
                 in the 
               
               
                   
                   
                 expression in 
                 presence 
                 of mir34b- 
                 presence of 
                 presence 
                 presence of 
               
               
                   
                 Gene Description 
                 log2 
                 of mir34a 
                 5p 
                 mir34c-5p 
                 of mir449a 
                 mir449b 
               
               
                   
                   
               
             
          
           
               
                 HIST1H3B 
                 history cluster 1, H3b 
                 7.71 
                 −0.57 
                 −0.42 
                 −0.74 
                 −1.03 
                 −0.66 
               
               
                 CDC2 
                 cell division cycle 2, G1 
                 5.59 
                 −0.57 
                 −0.29 
                 −0.64 
                 −1.00 
                 −0.67 
               
               
                   
                 to S and G2 to M 
               
               
                 DTL 
                 denticleless homolog 
                 6.47 
                 −0.65 
                 −0.38 
                 −0.86 
                 −0.97 
                 −0.81 
               
               
                   
                 ( Drosophila ) 
               
               
                 KLRK1/KLRC4 
                 killer cell lectin-like 
                 4.16 
                 −0.78 
                 −0.90 
                 −0.85 
                 −0.97 
                 −0.62 
               
               
                   
                 receptor subfamily K, 
               
               
                   
                 member 1/killer cell 
               
               
                   
                 lectin-like receptor 
               
               
                   
                 subfamily C, member 4 
               
               
                 KIAA0101 
                 KIAA0101 
                 6.71 
                 −0.88 
                 −0.65 
                 −0.84 
                 −0.92 
                 −0.72 
               
               
                 NUF2 
                 NUF2, NDC80 kinetochore 
                 6.20 
                 −0.91 
                 −0.55 
                 −0.68 
                 −0.92 
                 −0.75 
               
               
                   
                 complex component, 
               
               
                   
                 homolog ( S. cerevisiae ) 
               
               
                 HIST1H2BM 
                 histone cluster 1, H2bm 
                 8.72 
                 −0.44 
                 −0.59 
                 −0.69 
                 −0.92 
                 −0.66 
               
               
                 RAD51AP1 
                 RAD51 associated protein 1 
                 5.42 
                 −1.03 
                 −0.60 
                 −0.92 
                 −0.87 
                 −0.65 
               
               
                 CENPK 
                 centromere protein K 
                 6.38 
                 −0.89 
                 −0.60 
                 −0.74 
                 −0.83 
                 −0.65 
               
               
                 CCNB2 
                 cyclin B2 
                 6.51 
                 −0.65 
                 −0.55 
                 −0.59 
                 −0.83 
                 −0.77 
               
               
                 KIF11 
                 kinesin family member 11 
                 5.98 
                 −0.43 
                 −0.20 
                 −0.58 
                 −0.82 
                 −0.54 
               
               
                 NUSAP1 
                 nucleolar and spindle 
                 6.73 
                 −0.49 
                 −0.30 
                 −0.45 
                 −0.82 
                 −0.51 
               
               
                   
                 associated protein 1 
               
               
                 TOP2A 
                 topoisomerase (DNA) II 
                 7.06 
                 −0.70 
                 −0.21 
                 −0.63 
                 −0.80 
                 −0.52 
               
               
                   
                 alpha 170 kDa 
               
               
                 DEPDC1 
                 DEP domain containing 1 
                 5.22 
                 −0.80 
                 −0.39 
                 −0.54 
                 −0.80 
                 −0.71 
               
               
                 ASPM 
                 asp (abnormal spindle) 
                 5.73 
                 −0.59 
                 −0.32 
                 −0.62 
                 −0.77 
                 −0.67 
               
               
                   
                 homolog, microcephaly 
               
               
                   
                 associated ( Drosophila ) 
               
               
                 ARHGAP11B 
                 Rho GTPase activating 
                 4.69 
                 −0.82 
                 −0.75 
                 −0.71 
                 −0.76 
                 −0.84 
               
               
                   
                 protein 11B 
               
               
                 HELLS 
                 helicase, lymphoid- 
                 5.95 
                 −0.78 
                 −0.55 
                 −0.69 
                 −0.74 
                 −0.79 
               
               
                   
                 specific 
               
               
                 CENPI 
                 centromere protein I 
                 6.39 
                 −0.54 
                 −0.67 
                 −0.69 
                 −0.73 
                 −0.91 
               
               
                 CENPF 
                 centromere protein F, 
                 6.61 
                 −0.64 
                 −0.34 
                 −0.57 
                 −0.72 
                 −0.51 
               
               
                   
                 350/400 ka (mitosin) 
               
               
                 BUB1 
                 BUB1 budding uninhibited 
                 6.49 
                 −0.54 
                 −0.25 
                 −0.54 
                 −0.72 
                 −0.60 
               
               
                   
                 by benzimidazoles 1 
               
               
                   
                 homolog (yeast) 
               
               
                 RRM2 
                 ribonucleotide reductase 
                 7.72 
                 −0.57 
                 −0.29 
                 −0.76 
                 −0.71 
                 −0.60 
               
               
                   
                 M2 polypeptide 
               
               
                 TTK 
                 TTK protein kinase 
                 5.11 
                 −0.50 
                 −0.39 
                 −0.81 
                 −0.69 
                 −0.67 
               
               
                 ARHGDIB 
                 Rho GDP dissociation 
                 8.43 
                 −0.54 
                 −0.48 
                 −0.70 
                 −0.69 
                 −0.59 
               
               
                   
                 inhibitor (GDI) beta 
               
               
                 CEP55 
                 centrosomal protein 55 kDa 
                 6.68 
                 −0.52 
                 −0.37 
                 −0.62 
                 −0.68 
                 −0.64 
               
               
                 TPX2 
                 TPX2, microtubule- 
                 6.89 
                 −0.69 
                 −0.42 
                 −0.61 
                 −0.68 
                 −0.60 
               
               
                   
                 associated, homolog 
               
               
                   
                 ( Xenopus laevis ) 
               
               
                 FOXM1 
                 forkhead box M1 
                 6.22 
                 −0.64 
                 −0.37 
                 −0.38 
                 −0.66 
                 −0.56 
               
               
                 AURKA 
                 aurora kinase A 
                 7.42 
                 −0.51 
                 −0.38 
                 −0.51 
                 −0.65 
                 −0.66 
               
               
                 CASC5 
                 cancer susceptibility 
                 6.03 
                 −0.47 
                 −0.14 
                 −0.45 
                 −0.63 
                 −0.59 
               
               
                   
                 candidate 5 
               
               
                 SPC25 
                 SPC25, NDC80 kinetochore 
                 4.93 
                 −0.46 
                 −0.32 
                 −0.49 
                 −0.61 
                 −0.52 
               
               
                   
                 complex component, 
               
               
                   
                 homolog ( S. cerevisiae ) 
               
               
                 PRC1 
                 protein regulator of 
                 7.81 
                 −0.57 
                 −0.48 
                 −0.57 
                 −0.60 
                 −0.65 
               
               
                   
                 cytokinesis 1 
               
               
                 ARHGAP11A 
                 Rho GTPase activating 
                 6.53 
                 −0.40 
                 −0.24 
                 −0.46 
                 −0.60 
                 −0.53 
               
               
                   
                 protein 11A 
               
               
                 CDC25A 
                 cell division cycle 25 
                 6.33 
                 −0.60 
                 −0.46 
                 −0.54 
                 −0.59 
                 −0.55 
               
               
                   
                 homolog A ( S. pombe ) 
               
               
                 PRR11 
                 proline rich 11 
                 6.92 
                 −0.59 
                 −0.40 
                 −0.69 
                 −0.58 
                 −0.67 
               
               
                 CDC6 
                 cell division cycle 6 
                 7.64 
                 −0.38 
                 −0.22 
                 −0.57 
                 −0.57 
                 −0.52 
               
               
                   
                 homolog ( S. cerevisiae ) 
               
               
                 FLJ27243 
                 FLJ27243 protein 
                 6.60 
                 −0.48 
                 −0.54 
                 −0.47 
                 −0.55 
                 −0.65 
               
               
                 LOC100130131 
                 similar to melanoma 
                 6.14 
                 −0.32 
                 −0.44 
                 −0.34 
                 −0.54 
                 −0.51 
               
               
                   
                 antigen 
               
               
                 LOC100130131 
                 similar to melanoma 
                 6.14 
                 −0.32 
                 −0.44 
                 −0.34 
                 −0.54 
                 −0.51 
               
               
                   
                 antigen 
               
               
                 DLGAP5 
                 discs, large ( Drosophila ) 
                 6.64 
                 −0.68 
                 −0.09 
                 −0.48 
                 −0.52 
                 −0.50 
               
               
                   
                 homolog-associated 
               
               
                   
                 protein 5 
               
               
                 TRIP13 
                 thyroid hormone receptor 
                 7.35 
                 −0.54 
                 −0.57 
                 −0.58 
                 −0.51 
                 −0.55 
               
               
                   
                 interactor 13 
               
               
                 LOC253724 
                 hypothetical LOC253724 
                 3.82 
                 −0.59 
                 −0.70 
                 −0.95 
                 −0.51 
                 −0.79 
               
               
                 PLK4 
                 polo-like kinase 4 
                 6.23 
                 −0.43 
                 −0.18 
                 −0.58 
                 −0.50 
                 −0.55 
               
               
                   
                 ( Drosophila ) 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE XI 
               
             
             
               
                   
               
               
                 Predicted targets repressed and common to mir-449a, mir-449b, mir-34a, mir-34b* and mir-34c-5p and 
               
               
                 repressed after transfection of each of the miRNAs selected in HAECs. 
               
             
          
           
               
                   
                   
                 Level of 
                   
                   
                   
                   
                   
               
               
                   
                   
                 intensity 
                   
                 Modulation 
                 Modulation 
                 Modulation 
                 Modulation 
               
               
                   
                   
                 of 
                 Modulation 
                 in 
                 in presence 
                 in 
                 in 
               
               
                   
                   
                 expression 
                 in presence 
                 presence 
                 of mir34c- 
                 presence 
                 presence 
               
               
                 Gene_Symbol 
                 Gene Description 
                 in log2 
                 of mir34a 
                 of mir34b* 
                 5p 
                 of mir449a 
                 of mir449b 
               
               
                   
               
             
          
           
               
                 DTL 
                 denticleless homolog ( Drosophila ) 
                 6.47 
                 −0.65 
                 −0.38 
                 −0.86 
                 −0.97 
                 −0.81 
               
               
                 KLRK1//KLRC4 
                 killer cell lectin-like receptor 
                 4.16 
                 −0.78 
                 −0.90 
                 −0.85 
                 −0.97 
                 −0.62 
               
               
                   
                 subfamily K, member 1 
               
               
                 KIAA0101 
                 KIAA0101 
                 6.71 
                 −0.88 
                 −0.65 
                 −0.84 
                 −0.92 
                 −0.72 
               
               
                 CENPK 
                 centromere protein K 
                 6.38 
                 −0.89 
                 −0.60 
                 −0.74 
                 −0.83 
                 −0.65 
               
               
                 CCNB2 
                 cyclin B2 
                 6.51 
                 −0.65 
                 −0.55 
                 −0.59 
                 −0.83 
                 −0.77 
               
               
                 KIF11 
                 kinesin family member 11 
                 5.98 
                 −0.43 
                 −0.20 
                 −0.58 
                 −0.82 
                 −0.54 
               
               
                 NUSAP1 
                 nucleolar and spindle associated 
                 6.73 
                 −0.49 
                 −0.30 
                 −0.45 
                 −0.82 
                 −0.51 
               
               
                   
                 protein 1 
               
               
                 TOP2A 
                 topoisomerase (DNA) II alpha 170 
                 7.06 
                 −0.70 
                 −0.21 
                 −0.63 
                 −0.80 
                 −0.52 
               
               
                   
                 kDa 
               
               
                 DEPDC1 
                 DEP domain containing 1 
                 5.22 
                 −0.80 
                 −0.39 
                 −0.54 
                 −0.80 
                 −0.71 
               
               
                 RRM2 
                 ribonucleotide reductase M2 
                 7.72 
                 −0.57 
                 −0.29 
                 −0.76 
                 −0.71 
                 −0.60 
               
               
                   
                 polypeptide 
               
               
                 ARHGDIB 
                 Rho GDP dissociation inhibitor 
                 8.43 
                 −0.54 
                 −0.48 
                 −0.70 
                 −0.69 
                 −0.59 
               
               
                   
                 (GDI) beta 
               
               
                 CEP55 
                 centrosomal protein 55 kDa 
                 6.68 
                 −0.52 
                 −0.37 
                 −0.62 
                 −0.68 
                 −0.64 
               
               
                 TPX2 
                 TPX2, microtubule-associated, 
                 6.89 
                 −0.69 
                 −0.42 
                 −0.61 
                 −0.68 
                 −0.60 
               
               
                   
                 homolog ( Xenopus laevis ) 
               
               
                 FOXM1 
                 forkhead box M1 
                 6.22 
                 −0.64 
                 −0.37 
                 −0.38 
                 −0.66 
                 −0.56 
               
               
                 AURKA 
                 aurora kinase A 
                 7.42 
                 −0.51 
                 −0.38 
                 −0.51 
                 −0.65 
                 −0.66 
               
               
                 PRC1 
                 protein regulator of cytokinesis 1 
                 7.81 
                 −0.57 
                 −0.48 
                 −0.57 
                 −0.60 
                 −0.65 
               
               
                 CDC25A 
                 cell division cycle 25 homolog A 
                 6.33 
                 −0.60 
                 −0.46 
                 −0.54 
                 −0.59 
                 −0.55 
               
               
                   
                 ( S. pombe ) 
               
               
                 CDC6 
                 cell division cycle 6 homolog 
                 7.64 
                 −0.38 
                 −0.22 
                 −0.57 
                 −0.57 
                 −0.52 
               
               
                   
                 ( S. cerevisiae ) 
               
               
                   
               
             
          
         
       
     
     Bioinformatic analysis using the Ingenuity Pathway Analysis software (IPA) (Ingenuity Systems, Mountain View, USA) made it possible to identify networks of interaction between these genes and associate biological functions and diseases with the experimental results (see  FIG. 13 ). 
     The pathways regulated by expression of the selected miRNAs are major pathways for regulation of the cell cycle. 
     VI—Investigation of the Functional Effect of Suppression of Expression of the miR-449s on Ciliogenesis 
     The effect of extinction of expression of the miR-449s on ciliogenesis was then investigated. 
     VI-A. Material and Methods 
     HAEC Cells 
     Six independent cultures of HAEC cells were transfected with an oligonucleotide directed against the miR-449s and conjugated with a cholesterol molecule; ciliogenesis was evaluated during the regeneration time. 
     These tests use an antisense oligonucleotide of miR-449a (antagomir) bound at 3′ by a 2′-O-methyl bond to a molecule of cholesterol and with the sequence: 5′-a s c s c s agcuaacaauacacugc s c s a-Chol-3′ (SEQ. ID. No. 207) (the phosphorothioate bonds are indicated by the subscript J (obtained according to Eurogentec (Seraing, Belgium). 
     This antagomir targets miR-449a of  Homo sapiens  (complete correspondence) and miR-449b with a mispairing. 
     The negative control used is Clear-miR™ of sequence: 5′-c s a s uscgucgaucguagcg s c s a-Chol-3′ (SEQ. ID. No. 208) from Eurogentec. 
     The antagomir (100 μM) was preincubated in fetal calf serum (FCS) for 30 min RT. Then the antagomir-FCS mixture in a differentiation medium (20 μM of antagomir) is added on the apical face of the primary HAEC cells. After 2 h at 37° C., the mixture is withdrawn to restore the air-liquid interface. 
     Transfection is renewed every 5 days with a freshly prepared antagomir until the control cells have reached complete differentiation (generally after 21 days). 
     
       Xenopus laevis  
     
     The morpholino (MO) oligonucleotides directed against the miR-449s (GeneTools, LLC, Philomath, Oreg., USA) have the sequences: 
     
       
         
               
               
             
           
               
                 MO-449a: 
                   
               
               
                 5′-ACCAGCTAACATTACACTGCCT-3′ 
                 (SEQ. ID. No. 209) 
               
               
                   
               
               
                 MO-449b: 
                   
               
               
                 5′-GCCAGCTAAAACTACACTGCCT-3′ 
                 (SEQ. ID. No. 210) 
               
               
                   
               
               
                 MO-449c: 
                   
               
               
                 5′-ACAGCCAGCTAGCAAGTGCACTGCC-3′ 
                 (SEQ. ID. No. 211) 
               
               
                 and 
                   
               
               
                   
               
               
                 the control MO: 
                   
               
               
                 5′-TGCACGTTTCAATACAGACCGT-3′ 
                 (SEQ. ID. No. 212) 
               
             
          
         
       
     
     The anti-DLL1 MO used is that described by Morichika et al. ( Dev Growth Differ  52 (2), 235 (2010)). 
     VI-B. Results and Discussion 
     The miR-449 invalidated by its antagomir leads to a significant reduction in the number of ciliated HAEC cells at stage ALI-D21 (mean value of inhibition of ciliogenesis: 2.3±0.3, n=6, P&lt;0.001) (see  FIG. 14 ), in parallel with a reduction of the same order in the expression of miR-449 ( FIG. 14 , micrograph b). 
     MiR-449 was also invalidated in the cells of  Xenopus  embryos by epidermal injection of a mixture of morpholino oligonucleotides targeting the mature miR-449. The invalidation of miR-449 prevents multiciliogenesis, as revealed by staining with acetylated tubulin at the stage of embryonic development of the tail bud and in the tadpoles (n=112) (see  FIG. 14 , micrographs c to i). 
     Multiciliogenesis requires: (i) a definite end of the cell cycle, followed by (ii) centriologenesis characterized by multiplication of hundreds of basal bodies, derived from freshly synthesized centrioles; (iii) migration of the basal bodies to the apical membrane where they act as centers of organization of the microtubules and permit assembly of the mobile axonemes. 
     In the two models investigated, the ratio of tubulin-positive cells (staining of the cilia) and of centrin-2-positive cells (staining of the basal bodies) is not affected by suppression of the expression of miR-449, which suggests that miR-449 acts before formation of the centrioles. 
     It is interesting to note that whereas invalidation of miR-449 in the epidermis of  Xenopus  suppresses multiciliogenesis, it did not suppress the expression of the mRNAs of the markers of the ciliated cells including α-tubulin, Tex15 and the transcription factor Foxj1 (see  FIG. 15 ). These data indicate that miR-449 is necessary for terminal differentiation, but not for specification of the multiciliated cells, thus confirming the role of miR-449 as principal regulator of ciliogenesis in vertebrates. 
     VII—Effect of Transfection of miR-449 on the Targets of miR-449 
     In order to evaluate the effect of miR-449 on ciliogenesis, it seemed desirable to verify that the targets of miR-449 were inhibited during terminal differentiation and after transfection of miR-449. 
     VII-A. Material and Methods 
     Analysis of the Cell Cycle by Flow Cytometry 
     The cell cycles of A549 cells of lung adenocarcinoma are synchronized by overnight culture by serum deficiency and then transfected with the microRNAs; the cells are then cultured in DMEM supplemented with L-glutamine and 10% FCS up to 30% confluence. The cells are collected 48 h later, fixed with 80% ethanol and stained with 0.1 ml of propidium iodide solution (37° C., 30 minutes) containing RNAse A (50 μg/ml). 
     The data are read on a FACScalibur flow cytometer (Becton-Dickinson). The percentages of cells in phase G1, S and G2+M were calculated with the Pro Cellquest software. 
     Construction of the Plasmids and Measurements of Luciferase Activity 
     Complete or partial sequences of the untranslated 3′ region of Areg, Ccnb1, Ccne2, Cdc25a, DII1 and Notch1 were amplified and cloned in the psiCheck2 vector (Promega). 
     The constructions of psiCheck vectors thus obtained were cotransfected with synthetic microRNAs or a negative control (Ambion, Applied System) in HEK293T cells. The luciferase activity is measured as described by Pottier et al. ( PLoS One  4 (8), e6718 (2009)). 
     VII-B. Results 
     The targets of miR-449 were defined by analysis of the following expression profiles: (i) at four stages of regeneration of HAEC cells (ALI-D0, ALI-D7, ALI-D14, ALI-D21), (ii) with multiplying HAEC cells transfected with miR-449. Functional annotation of the mRNAs differentially expressed by Gene Set Enrichment Analysis (GSEA) (Edgar et al.  Nucleic Acids Res  30 (1), 207 (2002)) reveals a significant increase in genes associated with the G2/M stage and with ciliogenesis (see  FIG. 16 ). 
     The transcripts modulated by miR-449 are analyzed with tools for predicting targets of the microRNAs (http://www.microarray.fr:8080/merge/index) leading to the identification of several potential targets of this microRNA, which were validated with a luciferase test ( FIG. 17 , micrographs a, c). 
     A first group of validated targets of miR-449a/b comprises amphiregulin (Areg), cyclin B1 (Ccnb1), cyclin E2 (Ccne2), and the cell division cycle 25 homolog A (Cdc25A), which code for proteins involved in regulation of the cell cycle. In fact, transfection of miR-449 leads to stoppage of the cell cycle in phase G1 ( FIG. 17   b ), as reported by Feng, M. et al. ( Cell Cycle  (2), 213 (2010)), Lize et al. ( Cell Death Differ  (2009), Noonan et al. ( Oncogene  28 (14), 1714 (2009)) and Yang, X. et al. ( Genes Dev  23 (20), 2388 (2009)), and is a crucial step before initiation of centriogenesis. 
     A second group of validated targets of miR-449 is composed of Notch 1 and of the Notch ligand, DLL1 ( FIG. 17   c ). Interestingly, blocking of the Notch signalling pathway with a γ-secretase antagonist (DCT, 10 μM) during regeneration of the HAEC cells potentiates ciliogenesis significantly ( FIG. 17   d ), which is in agreement with the review of Tsao et al. ( Development  136 (13), 2297 (2009)). 
     These results are consistent with the observation that the precursors of the ciliated cells of the  Xenopus  epidermis transiently express the ligand DII1 of Notch at the moment of their specialization and that expression of DII1 decreases rapidly with time in parallel with the accumulation of miR-449 in these progenitors ( FIG. 17   e ). 
     As could be foreseen from this observation, endogenous expression of DII1 remained high in the precursors of the ciliated cells of the embryos modified with the MO miR-449 ( FIG. 17   e  and  f ) suggesting that miR-449 represses the expression of DII1. 
     VIII— Effect of the Sustained Activity of DII1 on Ciliogenesis 
     The consequences of sustained activity of DII1 on ciliogenesis were then evaluated. 
     Injection of a synthetic RNA of DII1 lacking a binding site to miR-449 results in (1) excessive specialization of the ciliated cells, (2) deficient ciliogenesis in the vast majority of these cells, a phenotype identical to that observed in embryos depleted of miR-449 ( FIG. 17   g ). 
     Lateral inhibition by Notch signalling is known to suppress the identity of the multiciliated cell. The increase in specification of the ciliated cells observed after overexpression of DII1 is probably caused by inhibition of the activity of Notch, as reported by Deblandre et al. ( Development  126 (21), 4715 (1999)). 
     In parallel, suppression of expression of endogenous DII1 by morpholino oligonucleotides led to excessive specification of the ciliated cells ( FIG. 17   g ). Thus, miR-449 can trigger multiciliogenesis by repressing the expression of DII1. In support of this model, deficient multiciliogenesis caused by extinction of the expression of miR-449 is effectively restored by inhibition of the target of miR-449, DII1 ( FIG. 17   g ). 
     Thus, these results show that repression of expression of DII1 is at the center of the mechanism of action of miR-449.