MAMMALIAN PRO-HORMONE CONVERTASE

Abstract: This invention relates to a novel and seventh member of the subtilisin-kexin family isolated from rat, which has been named rPC7. The rat spleen cDNA has been totally sequenced. A shorter DNA sequence has been obtained for human, which corresponds to a portion of the catalytic region of a human pro-hormone convertase corresponding to the rat pro-hormone convertase. PC7 clearly distinguishes from the other mammalian members of the subtilisin-kexin family. Its tissue distribution is ubiquitous, but its presence is particularly remarkable in lymphoid tissues. It is present in LoVo cells that are able to cleave the HIV gp160 protein into active gp120/gp41 proteins and that are deficient in other effective pro-hormone convertases known up to date. It is proposed that PC7 is a good candidate as a maturation enzyme responsible for the conversion of HIV gp160 protein in target CD<+4> cells. Therefore, silencing the expression of PC7 would lead to the inhibition of the activation of gp160.

Description: TITLE OF THE INVENTION Mammalian Pro-hormone convertase. FIELD OF THE INVENTION This invention relates to proteases, particularly to maturation enzymes, more particularly those of the subtilisin-kexin family. BACKGROUND OF THE INVENTION Numerous enzymes of the subtilisin-kexin family are known and they all have the characteristics of being able to recognize and cleave basic residues on proteic precursors. They differ from each other by their ability to cleave specific sequences containing mono- and dibasic residues. They also differ from each other by their tissue and intra-cellular distribution. In mammalians, pro-hormone convertases 1 to 6 are already known. A partial amino acid seguence of a new pro¬ hormone convertase has been obtained from a human squamous carcinoma cell line BEN. This amino acid sequence has been disclosed by an Australian group during a Keystone meeting that one of the inventors organized which was held at lake Tahoe, CA on March 2-8, 1995. This group presented a poster (Abstract number B7-102, J. Cellular Biochemistry, supplement 19B, 1995 p243) , wherein it has been shown that a new maturation enzyme was co-expressed in BEN cells with parathyroid hormone-related protein. No nucleotide sequence has been disclosed. STATEMENT OF THE INVENTION It is an object of the present invention to provide a new enzyme that has been isolated from rat cells which shows a considerable degree of homology with the partial amino acid sequence of the above-identified human enzyme and which will be called heretofore rat pro-hormone convertase 7 (rPC7) . This enzyme is a new member of the subtilisin-kexin family. This enzyme has an ubiquitous cell distribution, but which presence is particularly remarkable in immune system cells. The cDNA obtained from rat spleen has been partially sequenced and the amino acid sequence of rPC7 has been deduced therefrom. Furthermore, a cDNA encoding the partial amino acid sequence of the human PC7 has also been obtained, which sequence encodes a peptidic sequence identical to the one presented by the Australian group. Since rat and human PC7 are species variants and since it is well within the ability of those skilled in the art to derive other variants encoding a protein having the same activity as rPC7, PC7 nucleic acid variants are globally under the scope of this invention. More particularly, functional allelic variants and nucleic acid substitutions leading to PC7 conservative substituents are contemplated. It is another object of this invention to provide peptides which are common to human and rat PC7. These peptides can be used to elicit the production of antibodies capable of binding PC7 gene product of different species. It is further an object of this invention to provide antibodies directed to PC7. These antibodies are useful to detect the presence or amount of PC7 in cells or tissues of different mammalian species, assuming a conservation of proteic sequence between species, if one relies on the similarity of sequences existing between rat and human PC7 partial proteic sequences. These antibodies are useful as diagnostic reagents to detect the presence and/or amount of PC7. Therefore a kit and a method for detecting the presence and/or amount of PC7 in cells or tissues are also aspects of this invention. Kits and methods are conceived for different purposes such as Western blots, immunochemistry and immunological assays. Nucleic acid probes and oligonucleotides and methods and kits for detecting PC7 nucleic acids, particularly messenger RNAs present in cells or tissues of different mammalian species are also an object of this invention. Methods and kits are developed in different forms for example: for amplification methods like for polymerase chain reaction (PCR) , in si tu hybridization, Northern blots and detection of DNA fragments separated by electrophoresis, transferred and hybridized to labelled probes and oligonucleotides. Diagnostic reagents and probes are useful in the detection of this novel enzyme. Negative or positive results will provide information to the user as to whether a proteic precursor of a protein of interest present in a cell will be cleaved or not, if this precursor bears basic residues recognizable by PC7. Such utility has been already demonstrated for other members of this family. For example, in corticotroph cell line AtT-20, the absence of PC2 has been correlated with the lack of production of alpha-MSH and beta-End, while complementation of this cell line with PC2 coding sequence allowed the production of these two POMC gene products. As another example, reactive hypoglycemia has been correlated with a deficiency in PCI expression. Due to the specificity of cleavage of each pro-hormone convertase towards proteic precursors, this new enzyme may be useful in the maturation of precursors that have been found to be poor substrates to the already known convertases. The nucleic acid sequence encoding PC7 and sub- fragments thereof constitute an insert that can be cloned in plasmidic vectors in a sense or anti-sense fashion. These vectors may be bacterial plasmids, phages and expression vectors. Recombinant vectors comprising a PC7 sense insert are usable to produce PC7 gene product. Recombinant expression vectors comprising a PC7 antisense insert are usable to silence the expression of PC7 gene. Antisense oligonucleotides that are specific for PC7 are also usable to silence PC7 gene expression. One of the substrates cleavable by PC7 is HIV envelope glycoprotein gpl60. Cleavage of that protein leads to the production of gpl20 and gp41, the active and fusiogenic forms of the precursor gpl60. All the PC family members are capable of processing gplδO to gpl20/gp41. Amongst these, only PC4 has not been tested, since that enzyme is exclusively located in male germ cells. Although all the tested PC family members are capable of cleaving gplδO, only those located in major targets for HIV infection, namely furin, PC7 and PC5, are good candidates responsible for the formation of active viral glycoproteins. Furin and PC7 are enzymes which are expressed in CD4 + lymphocyte cell lines. PC5 is not located in all the studied CD4 + cell lines. Previous reports suggested that furin is important but not essential for the proteolytic maturation of gpl60 (Ohnishi, Y., et al. (1994) J. virol . 68 : 4075- 4079 and Gu, M. et al. (1995) FEBS Lett . 365:95-97). Furin is further capable of cleaving gpl20 into gp77 and gp53 products, which cleavage specificity appears exclusive to furin. PC7 is therefore another processing enzyme capable of forming gpl20 from gpl60 in the HIV target cells. Therefore it is an object of the invention to provide a method of preventing the conversion of gpl60 into gpl20/gp41 products, which method comprises the steps of contacting gpl60 mRNAs with a nucleic acid comprising an antisense construct of furin and an antisense construct of PC7 to silence the expression of the processing enzymes responsible for the cleavage of gpl60. Optionally, antisense nucleotides or oligonucleotides to mRNA or corresponding cDNA encoding PC5 is further included. Since gpl20 formation is required for HIV infectivity, it is further an object of the invention to provide a method of preventing the development of AIDS in a subject susceptible to infection by a HIV virus, which method comprises the step administering a composition comprising the above antisense constructs of furin and PC7. The antisense constructs may comprise complete antisense sequences to mRNAs or corresponding cDNAs encoding furin and PC7, or oligonucleotidic fragments of said complete antisense sequences. Optionally, antisense nucleotides or oligonucleotides to mRNA or corresponding cDNA encoding PC5 is further included. Compositions comprising antisense constructs used for the purpose of silencing PC7 are objects of the invention. More particularly, those capable of silencing the proteases responsible for the maturation to gpβO are objects of the invention. Since such compositions and methods may have severe adverse effects to the treated patients, it is conceivable that these compositions would comprise these antisense constructs or oligonucleotides included in formulations capable of targeting HIV-susceptible organs or cells. Such formulations may include liposomes, such as described in WO 96/10399 or any other liposomes, preferably those susceptible to accumulate preferentially in HIV-susceptible organs or cells. Other types of formulations may include nanoerythrosomes like the ones described in Lejeune et al. (1994) Anticancer Research 14: 915-920. To increase the specificity of targeting to the organs or cells susceptible to HIV infection, it is conceivable to conjugate the liposomes with a ligand specific to a membrane marker of such organs or cells. Since staining for PC7 has been observed in high percentage of brains of patients suffering of Down Syndrome or Alzheimer Disease as well as brains of elderly patients, notably in plaques and tangles, it further an object of this invention to provide a method of diagnosing one of these diseases in a patient affected thereby, which method comprises administering an adequate amount of labelled antibodies or antibody fragments specific to PC7 to these patients, and detecting the label accumulated in brain plaques and tangles as an indication of the presence of these diseases. An alternative method for diagnosing the same diseases would be to measure PC7 binding to the antibodies or antibody fragments in biological samples such as cerebrospinal fluid. The function of PC7 may be protective against these diseases and overexpression of PC7 via activation of its gene expression or gene delivery might be a novel approach to combat the development of plaques and tangles. DESCRIPTION OF THE INVENTION This invention will be described in details hereinbelow by way of specific practical examples and appended figures, which purpose is to illustrate the invention rather than to limit its scope. BRIEF DESCRIPTION OF THE FIGURES Figure 1 represents Northern blot analyses of PC7 in rat, mouse and human cell lines (top panel) and across rat tissues (bottom panel) . The estimated approximate size of PC7 mRNA is between 4.0-4.2 kb. The 22 established cell lines shown are [A] 12 constitutively secreting cells: HepG2 (hepatocellular carcinoma, human) , Cos-1, (kidney, African green monkey) , BSC40 (African green monkey kidney epithelial cells) , BRL-3A (liver cells, Buffalo rat) , Yl (adrenal cortex, mouse) , LoVo (colon adenocarcinoma, human) , NIH/3T3 (embryo, mouse) , Ltk" (connective tissue, mouse) , TM3 (testicular Leydig cells, mouse) , TM4 (testicular Sertoli cells, mouse) , Caco-2 (colon adenocarcinoma, human) and LLC-PK L (proximal kidney tubule epithelial cells, pig) . [B] 10 regulated cells containing endogenous s cr tory granules: . Neuro2A (neuroblastoma, mouse) , NG-108 (neuroblastomaglioma hybrids, rat-mouse) , SK-N-MIXC (neuroepithelioma, human) , GH4C1 (somatomammotroph, rat) , GH3 (somatomammotroph, rat) , AtT-20 (corticotroph, mouse) , C.T3-1 (gonadotrophs, mouse) , Rin m5F (insulinoma, rat) , PC12 (pheochromocytoma, rat) and βTC- 3 (insulinoma, mouse) . Figure 2 shows the results of in si tu hybridization histochemistry demonstrating the mRNA distribution of PC7 in the rat (A) thymus, (C) spleen and (E) lymph nodes. The specificity of the hybridization signal is demonstrated when compared to the adjacent controls shown in B, D and F, which were hybridized with the sense strand RNA probe. These data demonstrate that PC7 is expressed in various lymphocyte subpopulations including CD4 + and CD8 + cells. The CD4 + cells are the targets of infection by the HIV retrovirus and hence the presence of PC7 may well be important for the activation of the surface glycoprotein gplδO needed for viral infectivity. Figure 3 illustrates the partial cDNA and deduced amino acid sequences of rat PC7 (this sequence covers the entire structure of the active enzyme) . Figure 4 shows alignment of partial nucleotidic sequences of rat (top) and human (bottom) PC7, wherein identical sequences are connected by a vertical line. Figure 5 shows alignment of partial amino acid sequences of human (top) and rat (bottom) active PC7, wherein sequences susceptible to be PC7 specific . epitopes are underlined. History ς>£ the discovery of PC7; During a recent Keystone meeting that one of the inventors organized which was held at lake Tahoe, CA on March 2-8, 1995, an Australian group presented a poster (Abstract number B7-102, J. Cellular Biochemistry, supplement 19B, 1995 p243) in which they showed a deduced partial amino acid sequence of a novel subtilisin-kexin-like convertase based on a PCR fragment isolated from a human squamous carcinoma cell line BEN. No nucleotidic sequence was presented. Amino acid data presented by the Australian group His-Gly-Thr-Arg-Cys-Ala-Gly-Glu-Ser-Ala Xxx-Ser-Ser-Pro-Asn-Asn-Ser-Phe-Cys-Ala Val-Gly-Val-Ala-Tyr-Gly-Ser-Arσ-Ile-Ala Gly-Ile-Arg-Val-Leu-Asp-Gly-Pro-Leu-Thr Asp-Ser-Met-Glu-Ala-Val-Ala-Phe-Asn-Lys His-Tyr-Gln-Ile-Asn-Asp-Ile-Tyr-Ser-Cys Ser-Trp-Gly-Pro-Asp-Asp-Asp-Gly-Lys-Thr Val-Asp-Gly-Pro-His-Gln-Leu-Gly-Lys-Ala Ala-Leu-Gln-His-Gly-Val-Ile-Ala-Gly-Arg Gln-Gly-Phe-Glu-Gly-Ser-Ile-Phe-Val-Val Ala-Ser-Glγ-Asn-Glv-Glγ-Glu-His-Asn-Asp Asn-Cys-Asn-Cys SEQ ID NO.l Underlined amino acids represent the sequences which permitted the development of consensus degenerate sense and antisense oligonucleotides. Strategy of the choice of development of degenerate oligonucleotides based on human protein sequence of PC7 Based on this amino acid sequence, degenerate oligonucleotides were developed, which allowed the inventors to isolate a cDNA encoding the same amino acid sequence from total RNA of BEN cells as well as the equivalent mRNA from rat pituitary mRNA. Sense Oligonucleotide for hPC7 hPC7 Cys Ala Val Gly Val Ala Tyr Gly TGT GCT GTG GGC GTG GCT TAC GGT C C C T C C T C G T G G G G A A A A A A Consensus TGC GCC GTG GGC GTA GCA TAC GG T T A T C T T G TGY GCY GTR GGY GTV GCW TAY GG (SEQ ID NO: 2) hPACE4 TGC ATC GTG GGC ATA GCG TAC AAT mPACE4 TGC ATC GTG GGC ATC GCA TAT AAT rPACE4 TGC ATC GTG GGC ATA GCA TAT AAT hFurin TGT GGT GTA GGT GTG GCC TAC AAC mFurin TGT GGC GTA GGT GTA GCT TAC AAT rFurin TGT GGT GTA GGT GTA GCT TAC AAT mPC5 TGC ACC GTC GGG ATC GCT TTC AAC rPC5 TGC ACC GTT GGA ATC GCT TTC AAC mPC4 TGT GGT GCC GGT GTG GCC TTC AAT rPC4 TGT GGT GCC GGT GTG GCC TTC AAT mPCl TGT GGG GTT GGA GTT GCA TAT AAT rPCl TGT GGA GTT GGA GTT GCA TAT AAT hPCl TGC GGG GTT GGA GTT GCA TAC AAT mPC2 TGT GGA GTC GGC GTA GCA TAC AAC rPC2 TGT GGA GTC GGT GTA GCA TAC AAC pPC2 TGC GGG GTT GGA GTG GCC TAC AGC hPC2 TGT GGA GTT GGA GTA GCA TAC AAC Antisense Oligonucleotide for hPC7 hPC7 Gly Gly Glu His Asn Asp Asn Cys Asn Cys GGC GGC GAG CAC AAT GAT AAT TGT AAT TGT A A A T C C C C C C T T G G Consensus GGT GGC GAG CAC AAT GAC AAT TGT AAC TGT (Sense) G G A T C C C C ACA GTT ACA ATT GTC ATT GTG CTC GCC ACC (Antisense) G G G G A T C C RCA GTT RCA RTT GTC RTT RTG YTC SCC MCC (SEQ ID NO: 3) hPACE4 GGC GGG AGA GAG GGG GAC TAC TGC TCG TGC mPACE4 GGT GGG AGA GAA GGG GAC CAC TGC TCC TGT rPACE4 GGT GGG AGA GAA GGG GAC CAC TGC TCC TGT hFurin GGG GGC CGG GAA CAT GAC AGC TGC AAC TGC mFurin GGG GGC CGG GAA CAT GAC AGC TGC AAC TGT rFurin GGG GGC CGG GAA CAT GAC AGC TGT AAC TGT mPC5 GGT GGA CGG AGC AAG GAT CAC TGT TCT TGT rPC5 GGT GGA CGG AGT AAG GAC CAC TGC TCT TGT mPC4 GGT GGC CTC CAT TAC GAC AAC TGC AAT TGT rPC4 GGT GGC CTC CAC TAC GAC AAC TGC AAT TGT mPCl GGG GGT CGT CAG GGA GAT AAC TGT GAC TGT rPCl GGG GGT CGT CAA GGA GAT AAC TGT GAC TGT hPCl GGG GGG CGT CAG GGA GAT AAT TGT GAC TGT mPC2 GGT GGC AGC TAC GAT GAC TGC AAC TGT rPC2 GGT GGC AGC TAC GAT GAC --- TGC AAC TGT pPC2 GGT GGC AGC TAC GAC GAC TGC AAC TGT hPC2 GGC GGC AGC TAT GAC GAC --- TGC AAC TGC Deduced nucleotide and amino acid sequences of rat and human PC7 derived from PCR clones Using reverse-transcriptase PCR on rat pituitary total RNA and oligo-dT, the inventors amplified first strand cDNAs. These were then primed with the sense and antisense consensus oligonucleotides in a typical PCR reaction of 30 cycles with 20 sec at 94°C, 1 min at 52 °C and 2 min at 72°C. The amplified cDNA of 285 nts was subcloned into the vector PCRII and several positive clones were sequenced by the automated ALF sequencer. One clone called R14 gave the rat PC7 sequence which was used for Northern blot analyses, in si tu hybridization and to screen a lambda gtll cDNA library from rat spleen. Two other positive clones were isolated which permitted the identification of an extended rat cDNA sequence which encodes the complete protein. The active enzyme is encoded by amino acid residues 126 to 783 of SEQ ID NO: 5. The same strategy was used to isolate the cDNA sequence of human PC7 starting from RNA obtained from BEN cells. A fragment of 285 bp has been obtained and sequenced. A partial cDNA sequence of human PC7 is defined in SEQ ID NO: 4. The amino acid sequence deduced from SEQ ID NO: 4 is entirely comprised within the sequence disclosed by the Australian group. The rat 285 bp probe (PCR fragment) was then used to perform Northern blot of a multiplicity of cell lines as well as in si tu hybridization studies in rat tissues and cells. Results on Northern blot are represented in Figure 1 while those obtained from in situ hybridization are shown in Figure 2. The data clearly show the following properties of this novel mRNA which was called PC7: 1) From Northern blot analyses, it appears that PC7 transcripts are ubiquitously expressed in all tissues and cells examined, suggesting a widespread distribution, similar to furin, as it is expressed in cells with constitutive and regulated secretory pathways. 2) The sum of the in situ and Northern data suggest that PC7 is most abundantly expressed in the colon, the spleen, the thymus and the lymph nodes, all of which are lymphoid-associated tissues. 3) Analysis of the cellular expression of PC7 in established cell lines confirmed the ubiquitous expression of PC7 in all cells but also demonstrated its conservation of sequence in various species such as mouse, rat, human and pig. The richest source of PC7 was the mouse pituitary alpha-T3-l cell line derived from the gonadotrophs and the beta-TC3 cells line derived from a mouse insulinoma, the mouse fibroblast cell line Ltk" and the rat pheochromocytoma cell line PC12. 4) Furthermore, the expression of PC7 in the human colon carcinoma LoVo cell line is significant since this cell line is deficient in furin activity. This cell line is indeed known to express PACE4 and furin [Seidah, N. G. , Chretien, M. and Day, R. (1994) Biochimie 76, 197-209] . However, the LoVo furin has a point mutation which effectively makes it an inactive enzyme in this cell line [Takahashi, S., Kasai, K. , Hatsuzawa, K. , Kitamura, N., Misumi, Y. , Ikehara, Y., Murakami, K. and Nakayama, K. (1993) Biochem. Biophys. Res. Commun. 195, 1019- 1026.] . 5) Evidence has been presented that an enzyme other than furin is capable of processing the HIV gpl60 surface glycoprotein, based on [1] the ability of LoVo cells to activate this precursor into gpl20/gp41 [Ohnishi, Y., Shioda, T., Nakayama, K. , Iwata, S., Gotoh, B., Hamaguchi, M. and Nagai, Y. (1994) J. Virol. 68, 4075- 4079] , and [2] the results presented the inventors which demonstrated that in vi tro gpl60 is processed by both furin and PCI into gpl20/gp41 [Decroly, E. , Vandenbranden, M. , Ruysschaert, J. M. , Cogniaux, J. , Jacob, G. S., Howard, S. C, Marshall, G. , Kompelli, A., Basak, A., Jean, F., Lazure, C, Benjannet, S., Chretien, M., Day, R. and Seidah, N. G. (1994) J Biol Chem 2£9_(16), 12240-12247] . However, in the inventors' laboratory, when gpl60 was co-expressed in various cell lines with either PACE4, PCI, PC2, PC5 and its isoform PC5/6-B, furin was found to be by far the best processing enzyme of gpl60. Yet, LoVo cells can efficiently process this precursor even .though it is deficient in furin activity. This suggests that although furin is a good candidate processing enzyme of the AIDS virus gpl60, another as yet undefined enzyme present in LoVo cells can also do the job. It is proposed that PC7 may well be the sought second candidate enzyme and not PACE4 which is a weak processor of gpl60. It is not excluded that PC5 could also be a third candidate. However, PC5 was not expressed in all CD4 + cells studied. Pedugefl nucleo ide and amino acid sequences of rat spleen PC7 This sequence is shown in Figure 3 and the amino acid and nucleotidic sequences are defined in SEQ ID NO: 5 and 6, respectively. Referring to figure 3, the active sites Asp 150 , His 191 and Ser 369 (bold, underlined) , the oxyanion hole Asn 292 (bold) [♦♦] , as well as the putative zymogen activation site ArgAlaLysArg [1] are emphasized. It is envisaged that antisense oligonucleotides spanning these amino acid residues would silence the expression of PC7. The three putative Asn 130 - 138 ' 204 - 474 glycosylation sites are also shown [•••] . Amongst these, Asn 204 is located within the DNA stretch delineating the active sites. Antisense oligonucleotides spanning a cysteine residue may affect the expression of a correctly folding molecule. Such is particularly the case in the stretches of DNA around the sequence coding for His 191 , Asn 204 , Asn 292 , and Ser 369 wherein cys 195 - 208 - 300 - 361 residues are located in close vicinity, respectively (see Figure 3) . All the above-mentioned amino acid residues are amongst the targets of choice in the design of antisense oligonucleotides. The other Asn 163 site is not acceptable for N-glycosylation in view of the Pro 166 residue. The predicted Ser, Thr phosphorylation [**] and Tyr sulfatation [*] sites are depicted and the variant ArgArgGly≤ejzLeu sequence with its expected Ser phosphorylation site is also shown. Finally, the hydrophobic sequence, representing a putative transmembrane anchoring domain is underlined as: LeuValLeuValGlyCysPheSerValPheTrpThrlleTyrTyrMetLeu. The predicted polyadenylation signal AATAAA is also emphasized. The initiator methionine chosen occurs at nucleotide 218 giving a 36 amino acid signal peptide (-36 to -1) . The presence of an in-phase ATG as well as the stop codon TAA is to be noted. The available data will have important implications in pathologies of the immune system and in viral infections. These considerations were based on the following: a) The amino acid sequence of the catalytic domain of PC7 from both rat and human strongly suggest that PC7 will have a similar cleavage specificity to furin and would thus recognize both single basic residues and pairs of basic residues. Furthermore, based on the available specificity of furin [Siezen, RJ, Creemers, JWM and Van de Ven, WJM. (1994) Eur. J. Biochem. 222, 255-266] , it is suggested that PC7 may be better suited to cleave precursors with a negatively charged amino acid present three residues before the cleavage site (at P3) such as the case of the HIV gpl60 where the cleavage site is Arg-GLii-Lys-Arg-i and Glu occupies the P3 position. b) PC7 is ubiquitously distributed and its expression is particularly enriched in the immune system tissues and cells including the CD4 + cells which are infectable by the HIV virus. PC7 is therefore a target of choice toward which future inhibitors may be developed to inhibit the conversion of HIV gpl60 to gpl20/gp41. Inhibitors can be inter alia antisense nucleic acids or oligonucleotides capable of silencing the expression of PC7 in the target cells. c) The unique presence of an RRGSL sequence in the P- domain of PC7 which in all other members of the family is RRGDL is notable. This would imply a uniqueness of PC7 and may negate its possible interactions with surface integrin receptors which recognize the RGD sequence. Alignment of the sequence of PC7 with the other members of the subtilisin-kexin family This alignment (not shown) demonstrates that PC7 represents an ancestral PC gene product as it best resembles the yeast kexin-like enzymes kex2, krp, kexl and XRP-6 derived from four different yeast strains. In the mammalian PCs, the closest members are PCI and PC2. Nomenclature This novel gene product is called PC7 since it represents the seventh member of the subtilisin-kexin family. It should be noted that the name PC7 was recently published to erroneously suggest that a reported rat sequence represents a seventh member of this family [Tsuji, AS. et al. Biochem Biophys. Res. Commun. 202, 1452-1459, 1994] . However, sequence alignment clearly demonstrated that the published rat PC7 sequence is nothing but rat PACE4 which also has been published [Johnson, RC et al. Endocrinology 135, 1178-1185, 1994] . Therefore, the present inventors have decided to keep the name PC7, as it accurately reflects the rank of this enzyme in order of discovery of the convertases. Oligonucleotides useful as probes Since nucleotidic sequences for rat and human PC7 have been obtained, it is now.possible tq deduce which are the conserved sequences that are usable to detect the presence and/or amount of PC7 in different species. Comparison of human and rat sequences are shown in Figure 4. This alignment shows that a 38 nucleotide stretch (comprised between nucleotides 1043 and 1080 of SEQ ID NO: 6) is absolutely conserved between rat and human, suggesting that it could be used as an effective specific probe for the expression of PC7 in these species and presumably in other species. When this sequence was compared in both sense and anti sense orientations with the other six members of the mammalian family, the inventors calculated that the best alignment was with rat furin, PC4, PC2 and PC5 at 63% identity. Therefore, it is expected that hybridization performed at high stringency will give a specific signal for PC7 in various mammalian species. The following oligonucleotides and part thereof having at least about 15 nucleotides in length that will give the same specific signal for PC7 in stringent conditions are 5'CAC TAT CAG ATC AAT GAC ATC TAC AGC TGC AGC TGG GG3', 5'CC CCA GCT GCA GCT GTA GAT GTC ATT GAT CTG ATA GTG3' (SEQ ID NO: 7 AND 8, respectively) . They are to be used as well as the oligonucleotides which have the SEQ ID NOs: 2 and 3 and their reverse sequence (SEQ ID NOs: 11 and 12) as diagnosing reagents or as components of diagnostic kits to detect the presence and/or amount of PC7 encoding nucleic acids, preferably mRNAs, in conventional detection procedures (Northern blot, in si tu hybridization, for example) . A method of detection of PC7 which comprises the steps of contacting a cell sample (cells, tissues, lysates or cellular fractions thereof) with one the above oligonucleotides in selected hybridization conditions and detecting the presence and/or amount of hybridized oligonuleotides as an indication of the presence of PC7 is also new. Of course, these oligonucleotides or shorter subsets, as well as other oligonucleotides designed upon conserved sequences when aligning PC7 of other species can be used as primers in amplification methods. Development of specific antibodies to PC7 Alignment of peptidic sequences of rat and human PC7 is shown in Figure 5. The sequence HisGln ≤ϋGlyLysAlaAlaLeuGlnHis (SEQ ID NO: 9 corresponding to amino acid residues 265 to 274 of SEQ ID NO: 5) is absolutely conserved between the two species. It has only two amino acid identities with the other PCs (underlined) . This peptidic sequence is therefore considered as a sequence of choice to raise antibodies specific to PC7. Another 17 amino acid sequence which is unique to rat PC7 is also assumed to be an antigen susceptible to entail of the production of specific antibodies to PC7: AlaSerTyrValSerProMetLeuLysGluAsnLysAlaValProArgSer (SEQ ID NO: 10 corresponding to amino acids 485 to 501 of SEQ ID NO: 5) . This sequence is located in the C-terminal region which shows the greatest degree of divergence between PC7 and the other members of the family. It is assumed that this region will show a sufficient degree of similarity between species to entail of the production of antibodies recognizing PC7 in tissues or cells of different species. The antibodies raised against these peptides by using techniques well known in the art have been obtained and are to be used as diagnosing reagents or as components of diagnostic kits to detect the presence and/or amount of PC7 in conventional detection procedures (Western blot, immunohistochemistry, immunoassays, for example) . A method of detection of PC7 which comprises the steps of contacting a cell sample (cells, tissues, lysates or cellular fractions thereof) with a specific anti-PC7 diagnostic reagent in conditions allowing the binding of the antibodies to PC7 and detecting the presence and/or amount of bound antibodies as an indication of the presence of PC7 is also new. Probing other mammalian PC7 enzymes Part or totality of PC7 cDNA may be used to clone the same enzyme in other species, using either the cDNA as a probe to screen cDNA or genomic libraries or the PCR program outlined in this application. The oligonucleotides useful in the above diagnostic kit and method may be used as primers to initiate the PCR. Recombinant plasmids and hosts A variety of recombinant plasmids may now be constructed, using conventional techniques and commercially available plasmids. Expression vectors are particularly useful to produce PC7 in compatible host cells. It is also contemplated to insert the cDNA of PC7 in whole or in part in an antisense orientation in an expression vector such as pRcCMV or pCDNA-neo (InVitrogen) and to introduce these recombinant vectors in host cells by transfection or lipofection, for example, to silence the expression of PC7 gene in these cells. This procedure may be used in cell systems producing a proteic precursor wherein the presence of PC7 is undesirable, or to reveal pathologies correlated with a deficient production of PC7. Production of transgenic mice which are PC7-deficient (silenced PC7) are particularly contemplated as "knock-out" animal models wherein associated pathologies will be revealed, provided that such silencing is not lethal to embryos or to newborn animals. PC7 as a marker of Down Syndrome and Alzheimer Disease Using a specific PC7 antibody recognizing native PC7, we evaluated the PC7-immunoreactivity in a large number of Down Syndrome and Alzheimer Disease brains obtained post-mortem from the corresponding patients. As controls, we looked for immunoreactivity in normal brains. The areas targeted were the hippocampus and the frontal and temporal cortex. Staining for PC7 was found in 100% of Down's patients brains and 70% of Alzheimer disease brains and not in controls. Only the very aged control brains with some neuropathology (plaques, tangles etc ...) displayed some PC7 immunoreactivity. We therefore propose that PC7 is a very good marker, moreover an early marker, for the plaques in Alzheimer disease. Accordingly, measurement of PC7 in the brain may be a way to predict the early development of AD. It is also possible that measurement of PC7 in either cerebrospinal fluid or in periphery (much more accessible target) may also give us some indication of the development of this disease. The function of PC7 may well be protective and hence overexpression of PC7 via activation of its gene expression or gene delivery might be a way to exploit a novel approach to combat the development of the plaques and tangles. The invention has been described hereinbelow in details, but it is readily apparent for those skilled in the art that modifications or equivalents can be used, without departing from the teachings of the present disclosure. These modifications or equivalents are deemed to be part of the scope of this invention. SEQUENCE LISTING (1) GENERAL INFORMATION: (i) APPLICANTS: SEIDAH, Nabil G. DAY, Robert CHRETIEN, Michel (ii) TITLE OF THE INVENTION: MAMMALIAN PRO-HORMONE CONVERTASE (iii) NUMBER OF SEQUENCES: 12 (iv) CORRESPONDENCE ADDRESS: (A) ADDRESSEE: QUARLES & BRADY (B) STREET: 411 EAST WISCONSIN AVENUE (C) CITY: MILWAUKEE (D) STATE: WISCONSIN (E) COUNTRY: U.S.A. (F) ZIP: 53202-4497 (v) COMPUTER READABLE : (A) MEDIUM TYPE: 3.5 inch, 1.44 mB diskette (B) COMPUTER: IBM PS/ 56 486SLC3 (C) OPERATING SYSTEM: IBM-DOS 6.1 (D) SOFTWARE: WordPerfect 5.1 (vi) CURRENT APPLICATION DATA: (A) APPLICATION NUMBER: (B) FILING DATE: (C) CLASSIFICATION: (vii) PRIOR APPLICATION DATA: (A) APPLICATION: (B) FILING DATE: (viii) ATTORNEY/AGENT INFORMATION: (A) NAME: JEAN C. BAKER (B) REGISTRATION NUMBER: 35,433 (ix) TELECOMMUNICATION INFORMATION: (414) 277-5000 (A) TELEPHONE: (414) 277-5000 (B) TELEFAX: (414) 277-5591 (2) INFORMATION FOR SEQ ID NO: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 114 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 1 His Gly Thr Arg Cys Ala Gly Glu Ser Ala Xaa Ser Ser Pro Asn 5 10 15 Asn Ser Phe Cys Ala Val Gly Val Ala Tyr Gly Ser Arg Ile Ala 20 25 30 Gly Ile Arg Val Leu Asp Gly Pro Leu Thr Asp Ser Met Glu Ala 35 40 45 Val Ala Phe Asn Lys His Tyr Gin Ile Asn Asp Ile Tyr Ser Cys 50 55 60 Ser Trp Gly Pro Asp Asp Asp Gly Lys Thr Val Asp Gly Pro His 65 70 75 Gin Leu Gly Lys Ala Ala Leu Gin His Gly Val Ile Ala Gly Arg 80 85 90 Gin Gly Phe Glu Gly Ser Ile Phe Val Val Ala Ser Gly Asn Gly 95 100 105 Gly Glu His Asn Asp Asn Cys Asn Cys 110 (2) INFORMATION FOR SEQ ID NO: 2 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 23 bases (B) TYPE: nucleotides (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 2 TGYGCYGTRG GYGTVGCWTA YGG 23 (2) INFORMATION FOR SEQ ID NO: 3 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 30 bases (B) TYPE: nucleotides (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 3 RCAGTTRCAR TTGTCRTTRT GYTCSCCMCC 30 (2) INFORMATION FOR SEQ ID NO: 4 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 285 base pairs (B) TYPE: nucleotide (C) STRANDEDNESS: double (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 4 TGCGCTGTGG GCGTAGCATA TGGGAGCCGC ATCGCAGGTA TCCGGGTACT 50 GGATGGACCT CTCACAGACA GCATGGAGGC GGTGGCGTTC AACAAGCACT 100 ATCAGATCAA TGACATCTAC AGTTGCAGCT GGGGACCAGA TGACGATGGG 150 AGGACAGTGG ATGGCCCCCA TCAGCTTGGA AAGGCTGCCT TACAACATGG 200 GGTGATTGCT GGTCGCCAGG GCTTTGGGAG CATCTTTGTG GTAGCCAGTG 250 GCAACGGTGG GGAGCATAAC GACAACTGTA ACTGT 285 (2) INFORMATION FOR SEQ ID NO: 5 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 783 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 5 Met Pro Lys Gly Arg Gin Lys Val Pro Arg Leu Asp Ala Arg Leu 5 10 15 Gly Leu Pro Ile Cys Leu Cys Leu Glu Leu Ala Ile Phe Phe Leu 20 25 30 Val Pro Gin Val Met Gly Leu Thr Glu Ala Gly Gly Leu Asp Thr 35 40 45 Leu Gly Ala Gly Gly Leu Ser Trp Ala Val His Leu Asp Ser Leu 50 55 60 Glu Gly Glu Arg Lys Glu Glu Ser Leu Ile Gin Gin Ala Asn Ala 65 70 75 Val Ala Gin Ala Ala Gly Leu Val Asn Ala Gly Arg lie Gly Glu 80 85 90 Leu Gin Gly His Tyr Leu Phe Val Gin Pro Ala Gly His Gly Gin 95 100 105 Ala Met Glu Ala Glu Ala Met Arg Gin Gin Ala Glu Ala Val Leu 110 115 120 Ala Lys His Glu Ala Val Arg Trp His Ser Glu Gin Arg Leu Leu 125 130 135 Lys Arg Ala Lys Arg Ser Ile His Phe Asn Asp Pro Lys Tyr Pro 140 145 150 Gin Gin Trp His Leu Asn Asn Arg Arg Ser Pro Gly Arg Asp Ile 155 160 165 Asn Val Thr Gly Val Trp Glu Arg Asn Val Thr Gly Arg Gly Val 170 175 180 Thr Val Val Val Val Asp Asp Gly Val Glu His Thr Val Gin Asp 185 190 195 Ile Ala Pro Asn Tyr Ser Pro Glu Gly Ser Tyr Asp Leu Asn Ser 200 205 210 Asn Asp Pro Asp Pro Met Pro His Pro Asp Glu Glu Asn Gly Asn 215 220 225 His His Gly Thr Arg Cys Ala Gly Glu Ile Ala Ala Val Pro Asn 230 235 240 Asn Ser Phe Cys Ala Val Gly Val Ala Tyr Gly Ser Arg Ile Ala 245 250 255 Gly Ile Arg Val Leu Asp Gly Pro Leu Thr Asp Ser Met Glu Ala 260 265 270 Val Ala Phe Asn Lys His Tyr Gin Ile Asn Asp Ile Tyr Ser Cys 275 280 285 Ser Trp Gly Pro Asp Asp Asp Gly Lys Thr Val Asp Gly Pro His 290 295 300 Gin Leu Gly Lys Ala Ala Leu Gin His Gly Val Met Ala Gly Arg 305 310 315 Gin Gly Phe Gly Ser Ile Phe Val Val Ala Ser Gly Asn Gly Gly 320 325 330 Gin His Asn Asp Asn Cys Asn Tyr Asp Gly Tyr Ala Asn Ser Ile 335 340 345 Tyr Thr Val Thr Ile Gly Ala Val Asp Glu Glu Gly Arg Met Pro 350 355 360 Phe Tyr Ala Glu Glu Cys Ala Ser Met Leu Ala Val Thr Phe Ser 365 370 375 Gly Gly Asp Lys Met Leu Arg Ser Ile Val Thr Thr Asp Trp Asp 380 385 390 Leu Gin Lys Gly Thr Gly Cys Thr Glu Gly His Thr Gly Thr Ser 395 400 405 Ala Ala Ala Pro Leu Ala Ala Gly Met Ile Ala Leu Met Leu Gin 410 415 420 Val Arg Pro Cys Leu Thr Trp Arg Asp Val Gin His Ile Ile Val 425 430 435 Phe Thr Ala Thr Gin Tyr Glu Asp His Arg Ala Asp Trp Leu Thr 440 445 450 Asn Glu Ala Gly Phe Ser His Ser His Gin His Gly Phe Gly Leu 455 460 465 Leu Asn Ala Trp Arg Leu Val Asn Ala Ala Lys Ile Trp Thr Ser 470 475 480 Val Pro Tyr Leu Ala Ser Tyr Val Ser Pro Met Leu Lys Glu Asn 485 490 495 Lys Ala Val Pro Arg Ser Pro His Ser Leu Glu Val Leu Trp Asn 500 505 510 Val Ser Arg Thr Asp Leu Glu Met Ser Gly Leu Lys Thr Leu Glu 515 520 525 His Val Ala Val Thr Val Ser Ile Thr His Pro Arg Arg Gly Ser 530 535 540 Leu Glu Leu Lys Leu Phe Cys Pro Ser Gly Met Met Ser Leu Ile 545 550 555 Gly Ala Pro Arg Ser Met Asp Ser Asp Pro Asn Gly Phe Asn Asp 560 565 570 Trp Thr Phe Ser Thr Val Arg Cys Trp Gly Glu Arg Ala Arg Gly 575 580 585 Val Tyr Arg Leu Val Ile Arg Asp Val Gly Asp Glu Pro Leu Gin 590 595 600 Val Gly Ile Leu Gin Gin Trp Gin Leu Thr Leu Tyr Gly Ser Thr 605 610 615 Trp Ser Pro Val Asp Ile Lys Asp Arg Gin Ser Leu Leu Glu Ser 620 625 630 Ala Met Ser Gly Lys Tyr Leu His Asp Asp Phe Thr Leu Pro Cys 635 640 645 Pro Pro Gly Leu Lys Ile Pro Glu Glu Asp Gly Tyr Ser Ile Thr 650 655 660 Pro Asn Thr Leu Lys Thr Leu Val Leu Val Gly Cys Phe Ser Val 665 670 675 Phe Trp Thr Ile Tyr Tyr Met Leu Glu Val Cys Leu Ser Gin Arg 680 685 690 Ser Lys Ala Ser Thr His Gly Cys Arg Arg Gly Cys Cys Pro Trp 695 700 705 Pro Pro Gin Ser Gin Asn Ser Lys Glu Val Gly Thr Ala Leu Glu 710 715 720 Ser Met Pro Leu Cys Ser Ser Lys Asp Leu Asp Gly Val Asp Ser 725 730 735 Glu His Gly Asp Cys Thr Thr Ala Ser Ser Leu Leu Ala Pro Glu 740 745 750 Leu Leu Gly Glu Ala Asp Trp Ser Leu Ser Gin Asn Ser Lys Ser 755 760 765 Asp Leu Asp Cys Pro Pro His Gin Pro Pro Asp Leu Lys Asp Gly 770 775 780 Gin Ile Cys (2) INFORMATION FOR SEQ ID NO: 6 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 3450 base pairs (B) TYPE: nucleotide (C) STRANDEDNESS: double (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 6 CGGGGAAGCT GAGAGTTTCC GCAGGTGGCG GCTGCGGCGG CGGCGGCAGC 50 GGTAGCAACT GCAACAGTAG CAACGAAGGC TGTGGGTCTG CAGCTGTGTT 100 CCCAGTCGAC ATTGCTCACG GTGAAGGTGA CATCTCCCTC CAGTTTCACA 150 AAATGAGTGT GGTATGGTTA CGAAGACCAG GACCTAAACT TCACAGAGAG 200 CCCAGCCTGC TGTTCTGATG CCGAAAGGGA GACAGAAAGT CCCACGCTTG 250 GATGCCCGCC TGGGCCTGCC TATCTGCCTC TGTCTGGAAT TAGCCATCTT 300 CTTTCTGGTT CCCCAGGTCA TGGGCCTAAC AGAGGCAGGT GGTCTTGACA 350 CCTTGGGTGC AGGGGGGCTA AGCTGGGCTG TACATCTGGA CAGCCTAGAA 400 GGTGAGAGGA AGGAAGAGAG TCTGATACAA CAGGCAAATG CTGTGGCCCA 450 GGCAGCGGGG CTGGTGAATG CTGGGCGCAT TGGAGAGCTC CAGGGGCACT 500 ACCTCTTTGT CCAGCCAGCT GGGCACGGGC AAGCCATGGA GGCGGAGGCC 550 ATGCGGCAAC AGGCAGAGGC TGTGTTAGCC AAGCATGAAG CTGTGCGCTG 600 GCACTCAGAG CAGAGGCTGC TGAAGAGGGC CAAGCGCAGC ATCCACTTCA 650 ATGATCCCAA GTATCCTCAA CAGTGGCACC TGAATAATCG GCGGAGCCCA 700 GGAAGAGACA TCAATGTGAC AGGTGTGTGG GAGAGAAATG TAACTGGGCG 750 AGGGGTGACG GTGGTAGTGG TGGACGACGG AGTGGAGCAC ACCGTCCAGG 800 ACATTGCACC CAACTATAGC CCAGAGGGAA GCTATGACCT CAACTCTAAT 850 GACCCAGATC CTATGCCCCA CCCTGATGAG GAGAACGGTA ACCACCATGG 900 GACCCGGTGT GCAGGAGAAA TTGCAGCTGT GCCCAACAAC AGCTTCTGTG 950 CAGTAGGTGT GGCCTATGGG AGCCGAATAG CAGGTATCCG GGTGCTGGAT 1000 GGACCACTCA CAGACAGTAT GGAAGCTGTG GCATTCAACA AACACTATCA 1050 GATCAATGAC ATCTACAGCT GCAGCTGGGG CCCCGATGAT GATGGGAAGA 1100 CAGTGGATGG TCCTCATCAG CTTGGGAAGG CTGCCTTACA ACATGGAGTG 1150 ATGGCTGGTC GCCAAGGCTT TGGAAGTATC TTTGTGGTTG CCAGTGGTAA 1200 TGGTGGCCAG CACAATGACA ACTGCAACTA TGATGGCTAT GCCAACTCCA 1250 TCTACACTGT CACCATAGGA GCTGTGGATG AGGAGGGACG GATGCCTTTT 1300 TATGCAGAGG AGTGTGCCTC CATGCTGGCA GTCACCTTCA GTGGAGGAGA 1350 CAAGATGCTG CGGAGCATTG TGACTACTGA CTGGGACCTT CAGAAGGGCA 1400 CTGGCTGCAC TGAAGGCCAC ACAGGAACCT CAGCTGCAGC CCCTCTAGCA 1450 GCTGGCATGA TAGCTCTCAT GCTGCAGGTG CGGCCCTGCC TCACGTGGCG 1500 GGATGTCCAG CACATCATTG TCTTCACAGC CACTCAGTAT GAAGATCATC 1550 GTGCAGACTG GCTCACTAAT GAGGCTGGAT TCAGCCACAG CCATCAGCAT 1600 GGTTTCGGCC TGCTCAACGC CTGGAGACTT GTCAATGCAG CCAAGATCTG 1650 GACGTCTGTC CCTTACTTAG CTTCCTATGT CAGCCCCATG CTGAAAGAAA 1700 ATAAGGCTGT TCCACGGTCC CCCCACTCTC TGGAGGTCCT ATGGAATGTC 1750 AGCAGGACGG ACCTGGAGAT GTCGGGGCTG AAGACCCTGG AACATGTGGC 1800 GGTGACAGTC TCCATCACTC ACCCACGACG TGGCAGCTTA GAACTGAAAC 1850 TGTTTTGTCC CAGTGGCATG ATGTCTTTGA TCGGCGCGCC CCGCAGCATG 1900 GACTCGGACC CTAACGGCTT CAATGACTGG ACATTTTCCA CTGTGCGGTG 1950 CTGGGGGGAA AGAGCAAGAG GAGTCTACAG ACTGGTTATC AGGGATGTAG 2000 GAGATGAGCC GCTCCAGGTG GGCATCCTCC AGCAGTGGCA GCTGACGCTG 2050 TATGGCTCCA CGTGGAGTCC AGTAGACATC AAGGACAGAC AAAGTCTCTT 2100 AGAAAGTGCT ATGAGTGGAA AATACCTGCA TGATGACTTC ACTCTGCCTT 2150 GCCCACCTGG ACTGAAAATT CCTGAGGAGG ATGGTTACAG CATTACCCCT 2200 AACACACTCA AGACCCTTGT GCTGGTTGGC TGCTTCAGTG TCTTCTGGAC 2250 CATTTACTAC ATGCTAGAAG TGTGCCTGAG CCAGAGGAGC AAGGCTTCCA 2300 CCCATGGCTG CAGGAGAGGA TGCTGCCCCT GGCCCCCACA AAGCCAAAAC 2350 TCCAAGGAAG TGGGGACAGC ACTAGAATCA ATGCCACTGT GCAGCAGCAA 2400 GGACCTGGAT GGAGTGGATT CAGAGCACGG GGACTGCACA ACTGCCTCTA 2450 GCTTGCTGGC CCCAGAGCTG CTGGGGGAAG CTGACTGGAG TCTGTCCCAG 2500 AACAGTAAGA GTGACCTGGA TTGTCCTCCC CACCAACCCC CAGACCTGAA 2550 GGATGGACAG ATCTGCTGAC CCCAGAGCCC AGCTTCTTCC ATGTACAACA 2600 GGCTCTTCCT AAACTTGGTT ATGAGGCTTT CAATCATGGA TGCTCAGGAG 2650 AGAATGGTCC TGATAGTGAC ATCTGCCACC CAAGGCCTCT GAAGCATTCT 2700 CAGCCTTCTC AAGAGGGTGA GGGCCATCTT AATTAAGCGC AGTGGTAAGG 2750 GACTGGTGTT CATGGCTCCT CTAGCTGAGC TTTGCTGAGA GCCTTTCGAC 2800 AAGGGGTTGG CGCCCAGGCC AGGCAGCCCT TGATTTCATC TCTCTCGGGC 2850 TAGTCACTGT CCTCGGCCAT CAGGACCTCC ACCCCTTCAC AAGTTATGCA 2900 GCAGGTGCCT GTATACCTAG GAACACTCTC AACAGAAGTG CCGCTGTACC 2950 GAGGGCCCAG AGAGAGGCTG GCAAGAGCCT AGACATGCCT ACCCTGAAAG 3000 CAGCTGCCTT CATTACCCTT TCCTGTGTGC CTGTTCTGAA GCCCGTACCT 3050 TCACTACCAC TCACCCTTCC TGCTGAAGGA ATGGTGGCGT GTCCCAGGAA 3100 AACTGGGAGG CACAGGATTC CCAGCCAGCA CCCTTGCTGC CTCACTGGGG 3150 AAGTTGGCCT GCTGGGCTGC AGAGAGCTGA GACACAGTGT TGTCTAAGAT 3200 AGCATGGGAG CCCCTGCCTA TGACCACCTG TCTTCCTCTG CAAAGTGCTC 3250 AGGGAAATGG CCTTCATTCC AGAGGCCAGC TGTCCGCCTG ACTTTTCCTC 3300 CATTCTTGGC CTTCTCCCCT TCCCATCTTT GGAGCTAATT GTTAATATGA 3350 ATTTTTTAAT GCTTAAGATT TGATTTTTAC TTTTCAAAGC AACATTTTGT 3400 TGAATTTTTT TCTGCACAGC TTTCCAAAAT AAAAAGCAGA AGTAAAAAAA 3450 (2) INFORMATION FOR SEQ ID NO: 7 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 38 bases (B) TYPE: nucleotide (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 7 CACTATCAGA TCAATGACAT CTACAGCTGC AGCTGGGG 38 (2) INFORMATION FOR SEQ ID NO: 8 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 38 bases (B) TYPE: nucleotide (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 8 CCCCAGCTGC AGCTGTAGAT GTCATTGATC TGATAGTG 38 (2) INFORMATION FOR SEQ ID NO: 9 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 10 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 9 His Gin Leu Gly Lys Ala Ala Leu Gin His 5 10 (2) INFORMATION FOR SEQ ID NO: 10 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 17 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 10 Ala Ser Tyr Val Ser Pro Met Leu Lys Glu Asn Lys Ala Val Pro 5 10 15 Arg Ser (2) INFORMATION FOR SEQ ID NO: 11 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 23 bases (B) TYPE: nucleotide (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 11 CCRTAWGCBA CRCCYACRGC RCA 23 (2) INFORMATION FOR SEQ ID NO: 12 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 30 bases (B) TYPE: nucleotide (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 12 GGKGGSGARC AYAAYGACAA YTGYAACTGY 30

Claims: What is claimed is: 1. A purified pro-hormone convertase named PC7 isolated from rat tissue, having the amino acid sequence defined in SEQ ID NO: 5. 2. A nucleic acid encoding the pro-hormone convertase of claim 1. 3. A nucleic acid as defined in claim 2 which has the nucleotidic sequence defined in SEQ ID NO: 6, or a part or a variant thereof, said part having at least about fifteen nucleotides in length. 4. A nucleic acid encoding a portion of the catalytic region of a human pro-hormone convertase corresponding to the rat pro-hormone convertase of claim 1, which has the nucleotidic sequence defined in SEQ ID NO: 4, or a part or a variant thereof, said part having at least about fifteen nucleotides in length. 5. A peptidic fragment of the pro-hormone convertase defined in claim 1. 6. A peptidic fragment of the pro-hormone convertase as defined in claim 5, which has the amino acid sequence defined in SEQ ID NO: 9 or 10. 7. An antibody specific for the pro-hormone convertase defined in claim 1 or for a peptidic fragment as defined in claim 5 or 6. 8. A diagnostic reagent for detecting the presence and/or amount of PC7 comprising an antibody as defined in claim 7. 9. A diagnostic kit for detecting the presence and/or amount of PC7 comprising a diagnostic reagent as defined in claim 8. 10. An oligonucleotide having a nucleotidic sequence selected from the group consisting of SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 7 in whole or in part and SEQ ID NO: 8 in whole or in part, wherein said part is capable of a specific hybridization with a PC7 coding sequence in stringent conditions of hybridization. 11. An oligonucleotide having a nucleotidic sequence selected from the group consisting of SEQ ID NO: 3, SEQ ID NO: 8 and SEQ ID NO: 11. 12. An antisense oligonucleotide having at least 15 nucleotides in length spanning the PC7 amino acid residues Arg 101 , Ala 102 , Lys 103 , Arg 104 , Asp 150 , His 191 , Cys 195 , Asn 204 , Cys 208 , Asn 292 , Cys 300 , Cys 361 or Ser 369 of SEQ. ID. No. 5, or its counterpart in PC7 of mammalian species. 13. A diagnostic reagent for detecting the presence and/or amount of PC7 encoding nucleic acids, preferably messenger RNAs, comprising an oligonucleotide as defined in claim 10. 14. A diagnostic kit for detecting the presence and/or amount of PC7 encoding nucleic acids, preferably messenger RNAs, comprising a diagnostic reagent as defined in claim 13. 15. A recombinant DNA vector comprising the nucleic acid of any one claims 2, 3 and 4. 16. A recombinant DNA vector according to claim 15 which is a recombinant mammalian expression vector. 17. A recombinant DNA vector according to claim 16 wherein said nucleic acid is inserted in an antisense orientation in said vector. 18. A recombinant DNA vector according to claim 17, wherein said nucleic acid contains at least 15 nucleotides spanning the PC7 amino acid residues Arg 101 , Ala 102 , Lys 103 , Arg 104 , Asp 150 , His 191 , Cys 195 , Asn 204 , Cys 208 , Asn 292 , Cys 300 , Cys 361 or Ser 369 of the sequence defined in SEQ ID. No. 5 or spanning the corresponding amino acid residues in PC7 of mammalian species. 19. A recombinant host cell comprising the recombinant DNA vector of any one of claims 15 to 18. 20. A method of producing PC7 comprising the steps of culturing a recombinant host cell expressing the nucleic acid defined in claim 2 or 3 and recovering PC7 from said cell or from the culture medium. 21. A method of producing a protein from a proteic precursor comprising a sequence bearing basic amino acid residues and being cleavable by the pro-hormone convertase defined in claim 1, comprising the steps of: placing said precursor in the presence of the pro¬ hormone convertase or culturing a cell co-expressing said proteic precursor and this pro-hormone convertase, and recovering said protein. 22. A method according to claim 21 wherein said proteic precursor is HIV gpi60 glycoprotein and said protein consists of HIV gpl20 and/or gp41 glycoproteins. 23. A method of detecting the presence and/or amount of PC7 in cells or tissues of different mammalian species, which comprises the steps of: -contacting said cells, tissues, lysates or cellular fractions thereof with a diagnostic reagent as defined in claim 8 in conditions supporting the binding of said diagnostic reagent to constituents of said cells or tissues; and -measuring the bound diagnostic reagent as an indication of the presence and/or amount of PC7 in said cells or tissues. 24. A method of detecting the presence and/or amount of nucleic acids encoding PC7, preferably messenger RNAs, in cells or tissues of different mammalian species, which comprises the steps of: -contacting said nucleic acids with a diagnostic reagent as defined in claim 13 in conditions supporting hybridization of said diagnostic reagent to said nucleic acids; and -measuring the hybridized diagnostic reagent as an indication of the presence and/or amount of nucleic acids encoding PC7 in said cells or tissues. 25. A method of detecting the presence and/or amount of nucleic acids encoding PC7, preferably messenger RNAs, in cells or tissues of different mammalian species, which comprises the steps of: -contacting said nucleic acids with at least one oligonucleotide as defined in claim 10 as a primer for initiating amplification of a fragment of said nucleic acids in a polymerase-effected amplification method; and -measuring the amplified product as an indication of the presence and/or amount of nucleic acids encoding PC7 in said cells or tissues. 26. A method of silencing the expression of a gene encoding PC7 within a mammalian cell, which comprises the step of introducing the oligonucleotide of claim 11 or 12 into said cell. 27. A method of silencing the expression of a gene encoding PC7 within a mammalian cell, which comprises the step of introducing the recombinant vector of claim 17 or 18 into said cell. 28. A method as defined in claim 26 or 27 wherein said mammalian cell is a cell susceptible to infection by HIV. 29. A method as defined in claim 28 which results in the prevention of the activation of HIV gpl60 envelope glycoprotein. 30. A method as defined in claim 29 which results in the prevention of the development of AIDS in a patient susceptible to infection by HIV. 31. A method as defined in claim 23 wherein said tissues are plaques and tangles typical of Alzheimer Disease. 32. A method as defined in claim 31 which results in the diagnostic of Alzheimer Disease. 33. A composition comprising an oligonucleotide as defined in claim 11 or 12 or a recombinant vector as defined in claim 17 or 18. 34. A composition as defined in claim 33 further comprising an antisense oligonucleotide or a recombinant vector expressing an antisense nucleic acid, susceptible to silence the expression of furin. 35. A composition as defined in claim 33 or 34 wherein at least a part of oligonucleotides or recombinant vectors are entrapped in vesicles capable of targeting a tissue susceptible to HIV infection. 36. A composition as defined in claim 35, wherein said vesicles are nanoerythrosomes or liposomes. 37. A composition as defined in claim 36, wherein said vesicles are coupled at their surface to a ligand specifically binding a membrane marker specific to said tissue.

Inventors: CHRETIEN MICHEL, DAY ROBERT, SEIDAH NABIL G, CHRETIEN, MICHEL, DAY, ROBERT, SEIDAH, NABIL, G.
Applicants: CHRETIEN MICHEL, DAY ROBERT, MONTREAL INST RECH CLINIQUES, SEIDAH NABIL G, CHRETIEN, MICHEL, DAY, ROBERT, INSTITUT DE RECHERCHES CLINIQUES DE MONTREAL, SEIDAH, NABIL, G.
Application year: 1996
Main classification: C12N15
IPC codes: A61K48, C07K14, C07K16, C12N5, C12N9, C12N15, C12P21, C12Q1, C12R1, G01N33