SCIELLIN AND USES THEREOF

Abstract: The epidermal protein, sciellin, which forms part of the cornified envelope of keratinizing tissues has been characterized, as well as the gene which encodes the protein. Various methods of use of both the nucleic acid and protein are discussed.

Description: SCIELLIN AND USES THEREOF Background of the Invention The cornified envelope is a fifteen ( 15) run thick insoluble protein layer that is formed under the plasma membrane in the upper layers of epidermis and keratinizing stratified epithelium (Reichert, U. et al. (1993) Molecular Biology of the Skin, 107-150). It appears to play a major role in the physical barrier properties of the stratum corneum (Elias, P.M. and D.S. Friend (1975) J. Cell. Biol 65:180-191). The envelope is formed from several precursor proteins by the calcium dependent enzyme transglutaminase, which catalyzes formation of ε-(γ-glutamyl) lysine crosslinks (Polakowska, R.R. and L.A. Goldsmith (1991) Physiology, Biochemistry and Molecular Biology of the Skin, 168-201) that are resistant to proteolytic digestion. It has been postulated that crosslinking of an envelope related protein, involucrin, to the plasma membrane is a first step in envelope assembly (Ishida-Yamamoto, A. et al. (1997) J. Invest. Dermatol. \0S:\2-\6). This is followed by crosslinking of the less abundant precursors such as SPRR proteins, elafin, envoplakin, filaggrin, keratin filaments and cystatin a (Steinert, P.M. and L.N. Marekov (1995) J. Biol. Chem. 270:17702-17711; Takahashi, H. et al. (1997) J. Invest. Dermatol. 108:843-847; Ruhrberg, C. et al. (1996) J. Cell Biol. 134:715-729; Takahashi, M. et al. (1996) Arch. Biochem. and Biophys. 329:123-126). Finally loricrin covers the cytoplasmic side of the envelope (Candi, E. et al. (1995) J Biol. Chem. 270: 26382-26390). Several reports have suggested that multiple components are necessary for envelope structure and function. Involucrin for example acts as the framework for the attachment of other envelope components and is covalently linked to the lipids which are important components of the barrier of stratum corneum cells (Downing, D.T. (1992) J. Lipid Res. 33:301-313). The pancornulin proteins have been shown to act as molecular bridges and are able to cross-link with two different proteins (Li, V.W. et al. (1996) Dermatology Clinics 745-751). Loricrin can impart flexibility as a result of its high glycine content and insolubility from disulfide bonds. Gene mutation and knockout studies have been used to gather information on the function of epidermal proteins, with the keratins being the most well known (Fuchs, E. et al. (1992) PNAS 89:6906-6910; Vassar, R. et al. (1991) Cell 64:365-380). Only one study of envelope related proteins has been reported, a loricrin knockout mouse (deViragh, P. A. et al. (1996) J. Invest. Dermatol. 106:844; deViragh, P.A. et al. (1997) J. Invest. Dermatol. 108:555). Heterozygous mice are normal, while homozygotes have abnormal skin during the first few days, but the animals appear normal as adults. However, the mice have a 1 defect in barrier function and respond abnormally to the application of some chemicals. A mutation of the loricrin gene has been observed in patients with a rare autosomal dominant palmoplantar keratoderma, Vohwinkel's Keratoderma, as well as in Progressive, Symmetric Erythrokeratoderma (Ishida-Yamamoto, A. et al. (1997) J. Invest. DermatolΛ08'Λ2-l6). Loss of epidermal transglutaminase activity from mutations in the gene results in the human disease, lamellar ichthyosis, which is characterized by a thickened stratum corneum, disturbed epidermal keratinization and inflammatory changes (Huber, M. et al. (1995) Science 267:525-528). Summary of the Invention The present invention is based, in part, on the discovery of the gene which encodes the epidermal protein, sciellin. Accordingly, the present invention features a purified or isolated preparation or a recombinant preparation of sciellin, or a sciellin polypeptide. In a preferred embodiment, sciellin has at least 60% to about 70%, more preferably at least about 80%, even more preferably at least about 90% to about 95%, and most preferably at least about 99% sequence identity with human sciellin, e.g., the human sciellin of SEQ ID NO:2. Sciellin can be identical to a human sciellin sequence, e.g., that of SEQ ID NO:2. In another embodiment, sciellin is encoded by a nucleic acid molecule which hybridizes under stringent conditions to a nucleic acid molecule of the nucleic acid sequence shown in SEQ ID NO:l. In addition, sciellin can have substantially the same electrophoretic mobility as human sciellin, e.g., it appears as an electrophoretic band of about 75.3 kDa on reducing gels. Yet another preferred embodiment of the invention features a sciellin which is reactive with a sciellin-specific antibody, e.g., an antibody which binds to the epitope recognized by mAb 34D11, or a polyclonal antibody SC4. Antibodies against sciellin can be made by methods exemplified herein. In another preferred embodiment, sciellin is expressed by a recombinant cell, e.g., a bacterial cell, a cultured cell (e.g., a cultured eukaryotic cell) or a cell of a non-human transgenic animal. Cultured cells can include CHO cells or SF8 cells. Expression of sciellin in a transgenic animal can be general or can be under the control of a tissue specific promoter. Preferably, one or more sequences which encode sciellin or a fragment thereof are expressed in a preferred cell-type by a tissue specific promoter, e.g., a K14 promoter. Exemplary sequences encoding fragments of sciellin include, e.g., a sequence encoding the central domain of sciellin, e.g., one or more of repeats 1-16, or a sequence encoding a LLM domain. In a preferred embodiment, the recombinant sciellin differs from sciellen isolated from tissue in one or more of the following: its pattern of glycosylation, myristilation, phosphorylation, or other posttranslational modifications. 2 In a preferred embodiment, the recombinant sciellin preparation is free of other keratinocyte proteins, placental proteins, or other human proteins. In a preferred embodiment, the recombinant sciellin preparation contains at least 1, 10, or 100 μg of sciellin, or a sciellin polypeptide. In a preferred embodiment, the recombinant sciellin preparation contains at least 1, 10, or 100 mg of sciellin, or a sciellin polypeptide. In a preferred embodiment, the sciellin polypeptide has the following biological acitivities: 1) it is a precursor of the cornified envelope of keratinizing tissues; 2) it provides structural support to the cornified envelopes of stratum corneum cells; 3) it promotes adhesion between tissue elements; 4) it promotes intracellular signalling; 5) it defines cell shape; 6) it can act as an adaptor element to promote the assembly and targeting of multiprotein complexes; 7) it forms homotrimeric beta helices; (8) it is involved in the terminal differentiation of keratinocytes; and (9) it plays a role in development. In other preferred embodiments: the sciellin polypeptide includes an amino acid sequence with at least 60%, 80%, 90%, 95%, 98%, or 99% sequence identity to an amino acid sequence from SEQ ID NO:2; the sciellin polypeptide includes an amino acid sequence essentially the same as the amino acid sequence in SEQ LD NO:2; the sciellin polypeptide is at least 5, 10, 20, 50, 100, or 150 amino acids in length; the sciellin polypeptide includes at least 5, preferably at least 10, more preferably at least 20, most preferably at least 50, 100, or 150 contiguous amino acids from SEQ LD NO:2; the sciellin polypeptide is either, an agonist or an antagonist, of a biological activity of naturally occurring sciellin; the sciellin polypeptide is a vertebrate, e.g., a mammalian, e.g. a primate, e.g., a human, sciellin polypeptide. In a preferred embodiment, the invention includes a sciellin polypeptide encoded by a DNA insert of a plasmid deposited with ATCC as Accession No: . In another embodiment, the sciellin polypeptide is a polypeptide encoded by nucleotide sequences of the overlapping DNA inserts of more than one, preferably all four of the plasmids deposited with ATCC as Accession No: . In preferred embodiments: the sciellin polypeptide is encoded by the nucleic acid in SEQ ID NO: 1, or by a nucleic acid having at least about 85%, more preferably at least about 90% to about 95%, and most preferably at least about 99% sequence identity with the nucleic acid from SEQ ID NO:l. In preferred embodiments, the sciellin polypeptide includes an amino terminal domain, a central domain containing comprised of sixteen repeats, and/or a carboxy terminal domain containing a LIM domain. In preferred embodiments, the sciellin polypeptide includes a domain that includes at least one repeat, preferably 10 to 20 repeats, more preferably 14 to 18 repeats, and most 3 preferably about 16 repeats. Generally, the domain is about 20 residues in length, and preferably, has about 70, 80, 90, or 95% sequence identity with the protein sequence shown in SEQ ID NO: 2 (amino acid residues 231-543). Preferably, each repeat includes alternating stretches of hydrophobicity and hydrophilicity on hydropathy plots. Preferred hydrophobic stretches are about 3 to 10, preferably 4 to 9, most preferably, 5 to 7 residues in length. In one embodiment, the hydrophobic stretches can form beta sheets. In yet another embodiment, the invention features a sciellin polypeptide that does not include or has an inactivation in at least one repeat, preferably 10 to 20 repeats, more preferably 14 to 18 repeats, and most preferably about 16 repeats, which serves as an antagonist to one or more sciellin biological activities. In preferred embodiments, the sciellin polypeptide includes a LLM domain. Generally, the LIM domain is about 56 amino acids, and preferably has about 70, 80, 90, or 95%o sequence identity with the protein sequence shown in SEQ ID NO: 2 (amino acid residues 600-662). Preferably, the LLM domain folds into two independent structural domains with at least one cysteine and at least one histidine residues coordinating two zinc ions. In one embodiment, the LIM domain includes at least 5, preferably 6 to 7, and most preferably 8 of the cysteins and up to 3, most preferably one histidine found in native sciellin. In one embodiment, the LIM domain has a consensus sequence CX 2 CX t6- 23 HX CX 2 CX 2 CXι 6 . ιCX 2-3 (C,H,D), wherein X can be any amino acid. In a preferred embodiment, the sciellin polypeptide differs in amino acid sequence at up to 1, 2, 3, 5, or 10 residues, from a sequence in SEQ ID NO: 2. In other preferred embodiments, the sciellin polypeptide differs in amino acid sequence at up to 1, 2, 3, 5, or 10 % of the residues from a sequence in SEQ ID NO: 2. Preferably, the differences are such that: the sciellin polypeptide exhibits a sciellin biological activity, e.g., the sciellin polypeptide retains a biological activity of a naturally occurring sciellin. In preferred embodiments the sciellin polypeptide includes a sciellin sequence described herein as well as other N-terminal, and/or a C-terminal amino acid sequence. In preferred embodiments, the sciellin polypeptide includes all or a fragment of an amino acid sequence from SEQ ID NO: 2, fused, in reading frame, to additional amino acid residues, preferably to residues encoded by genomic DNA 5' to the genomic DNA which encodes a sequence from SEQ ID NO: 2. In yet other preferred embodiments, the sciellin polypeptide is a recombinant fusion protein having a first sciellin portion and a second polypeptide portion, e.g., a second polypeptide portion having an amino acid sequence unrelated to sciellin. The second polypeptide portion can be, e.g., any of glutathione-S-transferase, a DNA binding domain, or a polymerase activating domain. In a preferred embodiment the fusion protein can be used in a two-hybrid assay. For example, a first sciellin portion, e.g., a sciellin portion 4 containing a LIM domain, e.g., amino acids 550 to end encoded by the last exon, can be fused to a DNA binding domain. In a two hybrid assay, the first sciellin portion is co- expressed in a cell with a second polypeptide portion containing a transcription activation domain fused to an expression library, e.g., a keratinocyte library. In a preferred embodiment the sciellin polypeptide includes amino acid residues 231-543 of SEQ ID NO:2 In another embodiment, the sciellin polypeptide includes amino acids 600-662 of SEQ ID NO:2. In preferred embodiments the sciellin polypeptide has antagonistic activity, and is capable of: inhibiting formation of the cornified envelope in keratinizing tissues. In a preferred embodiment, the sciellin polypeptide is a fragment of a naturally occurring sciellin which inhibits formation of the cornified envelope in keratinizing tissues. Polypeptides of the invention include those which arise as a result of the existence of multiple genes, alternative transcription events, alternative RNA splicing events, and alternative translational and postranslational events. The sciellin polypeptide can be expressed in systems, e.g., cultured cells, which result in substantially the same postranslational modifications present when expressed sciellin is expressed in a native cell, or in systems which result in the omission of postranslational modifications present when expressed in a native cell. The invention includes an immunogen which includes a sciellin polypeptide in an immunogenic preparation, the immunogen being capable of eliciting an immune response specific for the sciellin polypeptide, e.g., a humoral response, an antibody response, or a cellular response. In preferred embodiments, the immunogen comprising an antigenic determinant, e.g., a unique determinant, from a protein represented by SEQ ID NO: 2. The present invention also includes an antibody preparation specifically reactive with an epitope of the sciellin immunogen or generally of a sciellin polypeptide, preferably an epitope which consists all or in part of residues from the the amino acid sequence of SEQ ID NO:2, or an epitope, which when bound to an antibody, results in the modulation of a biological activity. In preferred embodiments the sciellin-like polypeptide, as expressed in the cells in which it is normally expressed or in other eukaryotic cells, has a molecular weight of about 75.3 kDa as determined by SDS-PAGE. In another embodiment, the sciellin polypeptide comprises amino acid residues 1- 668 of Figure 2 (SEQ ID NO: 2). In a preferred embodiment, the recombinant sciellin polypeptide has one or more of the following characteristics: (i) it has the ability to form homotrimeric beta helices; (ii) it acts as a precursor of the cornified envelope of keratinizing tissues; 5 (iii) it provides structural support to the cornified envelopes of stratum corneum cells; (iv) it promotes adhesion between tissue elements; (v) it promotes intracellular signalling; (vi) it defines cell shape; (vii) it can act as an adaptor element to promote the assembly and targeting of multiprotein complexes; (viii) it has a molecular weight, amino acid composition or other physical characteristic of sciellin of SEQ ID NO:2; (ix) it has an overall sequence similarity of at least 50%, preferably at least 60%, more preferably at least 70, 80, 90, or 95%, with a sciellin polypeptide of SEQ ID NO:2; (x) it is found in human placenta; (xi) it has a central domain composed of repeats which is preferably about 70%, 80%, 90% or 95% identical to amino acid residues 231-543 of SEQ ID NO:2; (xii) it has a carboxyl domain containing a single LIM domain which is preferably about 70%, 80%, 90% or 95% identical to amino acid residues 600-662 of SEQ ID NO:2; (xiii) it has a pi of about 10; (xiv) it can be expressed in the stratum granulosum of human foreskin tissue; and (xv) it can expressed in the peripheral cytoplasm in hair follicles, upper cell layer of epidermis, as well as the epithelium of the oral cavity, esophagus, vagina, ureter and cornea. Also included in the invention is a composition which includes a sciellin polypeptide (or a nucleic acid which encodes it) and one or more additional components, e.g., a carrier, diluent, or solvent. The additional component can be one which renders the composition useful for in vitro and in vivo pharmaceutical or veterinary use. In another aspect, the invention provides an isolated or substantially pure nucleic acid having or comprising a nucleotide sequence which encodes a sciellin or a sciellin polypeptide, e.g., a sciellin or a sciellin polypeptide described herein. A preferred embodiment of the invention features a nucleic acid molecule having a nucleotide sequence at least about 85% sequence identity to a nucleotide sequence of SEQ LD NO: 1. In other preferred embodiments, the sciellin polypeptide is encoded by a nucleic acid molecule having a nucleotide sequence with at least about 90% to about 95%, and more preferably about 98% to about 99% sequence identity to the nucleotide sequence 6 from SEQ ID NO: 1. In another preferred embodiment, the sciellin polypeptide is encoded by the nulceic acid molecule of SEQ ID NO: 1. In prefered embodiments, the isolated nucleic acid molecule includes the nucleotide sequence of at least one and preferably all of the DNA inserts of the plasmids deposited with ATCC as Accession No: . In preferred embodiments, the subject sciellin nucleic acid will include a transcriptional regulatory sequence, e.g. at least one of a transcriptional promoter or transcriptional enhancer sequence, operably linked to the sciellin gene sequence (also referred to as LAMG3), e.g., to render the sciellin gene sequence suitable for use as an expression vector. In yet a further preferred embodiment, the nucleic acid which encodes a sciellin polypeptide of the invention, hybridizes under stringent conditions to a nucleic acid probe corresponding to at least 12 consecutive nucleotides of SEQ ID NO:l. More preferably, the nucleic acid probe corresponds to at least 20 consecutive nucleotides from SEQ LD NO: 1. The invention also provides a probe or primer which includes or comprises a substantially purified oligonucleotide. The oligonucleotide includes a region of nucleotide sequence which hybridizes under stringent conditions to at least 10 consecutive nucleotides of sense or antisense sequence from SEQ ID NO: 1, or naturally occurring mutants thereof. In preferred embodiments, the probe or primer further includes a label group attached thereto. The label group can be, e.g., a radioisotope, a fluorescent compound, an enzyme, and/or an enzyme co-factor. Preferably the oligonucleotide is at least 10 and less than 20, 30, 50, 100, or 150 nucleotides in length. The invention involves nucleic acids, e.g., RNA or DNA, encoding a sciellin polypeptide of the invention. This includes double stranded nucleic acids as well as coding and antisense single strands. In another aspect, the invention features a cell or purified preparation of cells which include a sciellin transgene, or which otherwise misexpress a sciellin gene. The cell preparation can consist of human or non human cells, e.g., rodent cells, e.g., mouse or rat cells, rabbit cells, or pig cells. In preferred embodiments, the cell or cells include a sciellin transgene, e.g., a heterologous form of a sciellin gene, e.g., a gene derived from humans (in the case of a non-human cell). The sciellin transgene can be misexpressed, e.g., overexpressed or underexpressed. In other preferred embodiments, the cell or cells include a gene which misexpress an endogenous sciellin gene, e.g., a gene the expression of which is disrupted, e.g., a knockout. Such cells can serve as a model for studying disorders which are related to mutated or mis-expressed sciellin alleles or for use in drug screening. 7 In another aspect, the invention features a transgenic sciellin animal, e.g., a rodent, e.g., a mouse or a rat, a rabbit, a pig, a goat, or a cow. In preferred embodiments, the transgenic animal includes (and preferably express) a heterologous form of a sciellin gene, e.g., a gene derived from humans. In a further embodiment, the sciellin transgene includes a tissue specific promoter, e.g., a K14 promoter. In other preferred embodiments, the animal has an endogenous sciellin gene which is misexpressed, e.g., a knockout. Such a transgenic animal can serve as a model for studying disorders which are related to mutated or mis-expressed sciellin alleles or for use in drug screening. In another aspect, the invention features, a method of inducing differentiation of keratinocytes. The method includes contacting a keratinocyte with an amount of a sciellin molecule described herein, or a sciellin agent, sufficient to induce differentiation. The sciellin agent can be an agonist or an antagonist of sciellin activity. The method can be performed in vivo, or in vitro. In in vivo methods the sciellin is administered to the subject. The administration can be directed to the site where differentiation is desired, e.g., by topical appication or by injection, or administered in a systemic fashion. In another aspect, the invention features, a method of promoting hair growth. The method includes contacting a hair stem cells with an amount of a sciellin molecule described herein or a sciellin agent, sufficient to induce hair growth. The sciellin agent can be an agonist or an antagonist of sciellin activity. The method can be performed in vivo, or in vitro. In in vivo methods the sciellin is administered to the subject. The administration can be directed to the site where hair growth is desired, e.g., by topical appication or by injection, or administered in a systemic fashion. In another aspect, the invention features, a method of promoting adhesion of a first tissue element to a second tissue element. The method includes contacting one or both of the first tissue element and the second tissue element with an amount of a sciellin molecule described herein or a sciellin agent, sufficient to promote adhesion. The sciellin agent can be an agonist or an antagonist of sciellin activity. The method can be performed in vivo, or in vitro. In in vivo methods the sciellin is administered to the subject. The administration can be directed to the site where adhesion is desired, e.g., by topical appication or by injection, or administered in a systemic fashion. A tissue element can be a cell or a multi-cellular on acellular structure. Examples of tissue elements include, skin cells, e.g., epidermal or dermal cells, or e.g., foreskin tissue, e.g., stratum granulosum, basement membrane or components of the basement membrane, hair follicles, epithelium in the oral cavity, esophagus, vagina, ureter and cornea, or any cell or structure which in normal, non-traumatized, or non-diseased tissue is adj ascent or adhered to a specific tissue element recited herein. In preferred embodiments the molecule is exogenous (e.g., administered to a subject) or is recombinant. In preferred embodiments the method is an vivo method. In vivo methods can be autologous, allogeneic, or xenogeneic. In autologous methods, adhesion between two tissue elements from the subject is promoted. In allogeneic methods, adhesion between a recipient tissue element and a donor tissue element from an allogeneic donor is promoted. In xenogeneic methods, adhesion between a recipient tissue element and a donor tissue element from a xenogeneic donor is promoted. Thus, one element can be a donor tissue element which is implanted into a recipient subject. In preferred embodiments the first tissue is healthy tissue, e.g., skin tissue, and the second tissue is wounded, e.g., burned, diseased, traumatized, cut, and the tissue, or is a wound bed. For example, the first tissue is skin tissue, from the subject or from a donor, and the second tissue is wounded, e.g., burned or abraided tissue. In preferred embodiments the first tissue and second tissue element are normally adhered but have become detached from one another due to trauma, burn or other physical injury, disease, or age. In preferred embodiments: the first tissue element is a dermal cell and the second tissue element is an epidermal cell; the first tissue element is e.g., foreskin tissue, e.g., stratum granulosum, hair follicles, part of the epithelium in the oral cavity, esophagus, vagina, ureter and cornea and the second tissue element is a cell or structure which in normal, non-traumatized, or non-diseased tissue is adjacent or adhered to said epithelium. The administration of sciellin can be repeated. In another aspect, the invention features a method of promoting wound healing in a subject. The method includes administering an amount of a sciellin molecule described herein or a sciellin agent, sufficient to promote healing to the wound. The sciellin agent can be an agonist or an antagonist of sciellin activity. The administration can be directed to the site where healing is desired, e.g., by topical appication or by injection, or administered in a systemic fashion. The wound can be in any tissue, but preferably in a tissue in which the sciellin normally occurs. Examples skin, e.g., foreskin tissue, e.g., stratum granulosum, hair follicles, tissues of the eye, e.g., the cornea, the basement membrane the epithelium in, e.g., the oral cavity, esophagus, vagina, ureter, or any tissue which in normal, non-traumatized, or non-diseased tissue is adjacent or adhered thereto. 9 In preferred embodiments the molecule is exogenous (e.g., administered to a subject) or is recombinant. In preferred embodiments the wound tissue is burned, diseased, traumatized, cut, the subject of immune attack, e.g, autoimmune attack, or abraided. The administration of sciellin can be repeated. In another aspect, the invention provides, a method of treating or preventing in a subject a sciellin- related disorder. The method includes: administering to the subject an effective amount of sciellin molecule, or a sciellin agonist, effective to treat or prevent the sciellin- related disorder in the subject. The sciellin agent can be an agonist or an antagonist of sciellin activity. The administration can be directed to the site where treatment or prevention is desired, e.g., by topical appication or by injection, or administered in a systemic fashion. In preferred embodiments, the subject is a mammal, e.g., human or non-human. Such sciellin-related disorders include, e.g., a disorder associated with the misexpression of sciellin; a skin disorder, e.g., a foreskin disorder; an epidermal disorder, e.g., a disorder characterized by disturbed epidermal characterization or a disorder in the stratum granulosum, e.g., ichthyosis; an ectodermal disorder, e.g., ectodermal dysplasia; a dermal disorder; a hair growth disorder, e.g., congenital allopecia; a disorder associated with a genetic lesion at chromosome 13, region q22; a disorder associated with abnormal levels, e.g., abnormally low levels, of adhesion between tissues; a disorder associated with the basement membrane; a disorder associated with abnormal keratinocyte activity; e.g., abnormal activity of keratinocytes in the epithelium of oral cavity, esophagus, vagina, ureter or cornea; or an inflammatory condition. In preferred embodiments the molecule is exogenous (e.g., administered to a subject) or is recombinant. The administration of sciellin can be repeated. In another aspect, the invention provides, a method of determining if a subject is at risk for a disorder related to a lesion in or the misexpression of a gene which encodes a sciellin described herein. Such disorders include, e.g., a disorder associated with the misexpression of sciellin; a skin disorder, e.g., a foreskin disorder; an epidermal disorder, e.g., a disorder characterized by disturbed epidermal characterization or a disorder in the stratum granulosum, e.g., ichthyosis; an ectodermal disorder, e.g., ectodermal dysplasia; a dermal disorder; a hair growth disorder, e.g., congenital allopecia; a disorder associated with a genetic lesion at chromosome 13, region q22; a disorder associated with abnormal levels, e.g., abnormally low levels, of adhesion between tissues; a disorder associated with the basement membrane; a disorder associated with abnormal 10 keratinocyte activity; e.g., abnormal activity of keratinocytes in the epithelium of oral cavity, esophagus, vagina, ureter or cornea; or an inflammatory condition. The method includes one or more of the following: detecting, in a tissue of the subject, the presence or absence of a mutation which affects the expression of the sciellin gene, or other gene which encodes a subunit of sciellin, e.g., detecting the presence or absence of a mutation in a region which controls the expression of the gene, e.g., a mutation in the 5' control region; detecting, in a tissue of the subject, the presence or absence of a mutation which alters the structure of the sciellin gene; detecting, in a tissue of the subject, the misexpression of the sciellin gene, at the mRNA level, e.g., detecting a non- wild type level of a sciellin mRNA ; detecting, in a tissue of the subject, the misexpression of the sciellin gene, at the protein level, e.g., detecting a non-wild type level of a sciellin polypeptide. In preferred embodiments the method includes: ascertaining the existence of at least one of: a deletion of one or more nucleotides from the sciellin gene; an insertion of one or more nucleotides into the gene, a point mutation, e.g., a substitution of one or more nucleotides of the gene, a gross chromosomal rearrangement of the gene, e.g., a translocation, inversion, or deletion. For example, detecting the genetic lesion can include: (i) providing a probe/primer including an oligonucleotide containing a region of nucleotide sequence which hybridizes to a sense or antisense sequence from SEQ ID NO: 1, or naturally occurring mutants thereof or 5' or 3' flanking sequences naturally associated with the LAMG3 gene; (ii) exposing the probe/primer to nucleic acid of the tissue; and detecting, by hybridization, e.g., in situ hybridization, of the probe/primer to the nucleic acid, the presence or absence of the genetic lesion. In preferred embodiments detecting the misexpression includes ascertaining the existence of at least one of: an alteration in the level of a messenger RNA transcript of the sciellin gene; the presence of a non-wild type splicing pattern of a messenger RNA transcript of the sciellin gene; or a non- wild type level of sciellin. Methods of the invention can be used prenatally or to determine if a subject's offspring will be at risk for a disorder. In preferred embodiments the method includes determining the structure of a sciellin gene, an abnormal structure being indicative of risk for the disorder. In preferred embodiments the method includes contacting a sample form the subject with an antibody to the sciellin protein or a nucleic acid which hybridizes specifically with the sciellin gene,. 11 In another aspect, the invention features, a method of evaluating a compound for the ability to interact with, e.g., bind, a subject sciellin polypeptide, e.g., sciellin or a fragment thereof, e.g., a central repeat domain, or a LIM domain, of sciellin. The method includes: contacting the compound with the subject sciellin polypeptide; and evaluating ability of the compound to interact with, e.g., to bind or form a complex with the subject sciellin polypeptide. This method can be performed in vitro, e.g., in a cell free system, or in vivo, e.g., in a two-hybrid interaction trap assay. This method can be used to identify naturally occurring molecules which interact with subject sciellin polypeptide. It can also be used to find natural or synthetic inhibitors of subject sciellin polypeptide. In another aspect, the invention features, a method of evaluating a compound, e.g., a polypeptide, e.g., a naturally occurring ligand of or a naturally occuring substrate to which binds a subject sciellin polypeptide, e.g., sciellin or a fragment thereof, e.g., a central repeat domain, or a LIM domain, of sciellin, for the ability to bind a subject sciellin polypeptide. The method includes: contacting the compound with the subject sciellin polypeptide; and evaluating the ability of the compound to interact with, e.g., to bind or form a complex with the subject sciellin polypeptide, e.g., the ability of the compound to inhibit a subject sciellin polypeptide/ligand interaction. This method can be performed in vitro, e.g., in a cell free system, or in vivo, e.g., in a two-hybrid interaction trap assay. This method can be used to identify compounds, e.g., fragments or analogs of a subject sciellin polypeptide, which are agonists or antagonists of a subject sciellin polypeptide. In another aspect, the invention features, a method of evaluating a first compound, e.g., a subject sciellin polypeptide, e.g., sciellin or a fragment thereof, e.g., a central repeat domain, or a LIM domain, of sciellin, for the ability to bind a second compound, e.g., a second polypeptide, e.g., a naturally occurring ligand of or substrate to which binds a subject sciellin polypeptide. The method includes: contacting the first compound with the second compound; and evaluating the ability of the first compound to form a complex with the second compound. This method can be performed in vitro, e.g., in a cell free system, or in vivo, e.g., in a two-hybrid interaction trap assay. This method can be used to identify compounds, e.g., fragments or analogs of a subject sciellin polypeptide, which are agonists or antagonists of a subject sciellin polypeptide. In yet another aspect, the invention features a method for evaluating a compound, e.g., for the ability to modulate an interaction, e.g., the ability to inhibit an interaction of a subject sciellin polypeptide, e.g., sciellin or a fragment thereof, e.g., a central repeat domain, or a LIM domain, of sciellin, with a second polypeptide, e.g., a polypeptide, e.g., 12 a natural ligand of the of or a substrate wo which binds a subject sciellin polypeptide, or a fragment thereof. The method includes the steps of (i) combining the second polypeptide (or preferably a purified preparation thereof), a subject sciellin polypeptide, (or preferably a purified preparation thereof), and a compound, e.g., under conditions wherein in the absence of the compound, the second polypeptide, and the subject sciellin polypeptide, are able to interact, e.g., to bind or form a complex; and (ii) detecting the interaction, e.g., detecting the formation (or dissolution) of a complex which includes the second polypeptide, and the subject sciellin polypeptide. A change, e.g., a decrease or increase, in the formation of the complex in the presence of a compound (relative to what is seen in the absence of the compound) is indicative of a modulation, e.g., an inhibition or promotion, of the interaction between the second polypeptide, and the subject sciellin polypeptide. In preferred embodiments: the second polypeptide, and the subject sciellin polypeptide, are combined in a cell-free system and contacted with the compound; the cell-free system is selected from a group consisting of a cell lysate and a reconstituted protein mixture; the subject sciellin polypeptide, and the second polypeptide are simultaneously expressed in a cell, and the cell is contacted with the compound, e.g. in an interaction trap assay (e.g., a two-hybrid assay). In yet another aspect, the invention features a two-phase method (e.g., a method having an in vitro, e.g., in a cell free system, and an in vivo phase) for evaluating a compound, e.g., for the ability to modulate, e.g., to inhibit or promote, an interaction of a subject sciellin polypeptide subject sciellin polypeptide, e.g., sciellin or a fragment thereof, e.g., a central repeat domain, or a LIM domain, of sciellin, with a second compound, e.g., a second polypeptide, e.g., a naturally occurring ligand of or a substrate to which binds a subject sciellin polypeptide, or a fragment thereof. The method includes steps (i) and (ii) of the method described immediately above performed in vitro, and further includes: (iii) determining if the compound modulates the interaction in vitro, e.g., in a cell free system, and if so; (iv) administering the compound to a cell or animal; and (v) evaluating the in vivo effect of the compound on an interaction, e.g., inhibition, of a subject sciellin polypeptide, with a second polypeptide. In another aspect, the invention features, a method of evaluating a compound for the ability to bind a nucleic acid encoding a subject sciellin polypeptide, e.g., sciellin or a fragment thereof, e.g., a central repeat domain or a LIM domain. The method includes: contacting the compound with the nucleic acid; and evaluating ability of the compound to form a complex with the nucleic acid. 13 In another aspect, the invention features a method of making a sciellin polypeptide, e.g., a peptide having a non-wild type activity, e.g., an antagonist, agonist, or super agonist of a naturally occurring sciellin polypeptide, e.g., a naturally occurring sciellin polypeptide. The method includes: altering the sequence of a sciellin polypeptide, e.g., altering the sequence , e.g., by substitution or deletion of one or more residues of a non-conserved region, a domain or residue disclosed herein, and testing the altered polypeptide for the desired activity. In another aspect, the invention features a method of making a fragment or analog of a sciellin polypeptide having a biological activity of a naturally occurring sciellin polypeptide. The method includes: altering the sequence, e.g., by substitution or deletion of one or more residues, of a sciellin polypeptide, e.g., altering the sequence of a non- conserved region, or a domain or residue described herein, and testing the altered polypeptide for the desired activity. In another aspect, the invention features, a human cell, e.g., a skin cell, e.g., an epithelial cell, e.g., a keratinocyte, transformed with nucleic acid which encodes a subject sciellin polypeptide. In another aspect, the invention includes: a sciellin nucleic acid, e.g., a sciellin nucleic acid inserted into a vector; a cell transformed with a sciellin nucleic acid; a sciellin made by culturing a cell transformed with a sciellin nucleic acid; and a method of making a sciellin polypeptide including culturing a a cell transformed with a sciellin nucleic acid. A "heterologous promoter", as used herein is a promoter which is not naturally associated with a gene or a purified nucleic acid. A "purified'Or "substantially pure" or isolated "preparation" of a polypeptide, as used herein, means a polypeptide that has been separated from other proteins, lipids, and nucleic acids with which it naturally occurs. Preferably, the polypeptide is also separated from substances, e.g., antibodies or gel matrix, e.g., polyacrylamide, which are used to purify it. Preferably, the polypeptide constitutes at least 10, 20, 50 70, 80 or 95% dry weight of the purified preparation. Preferably, the preparation contains: sufficient polypeptide to allow protein sequencing; at least 1, 10, or 100 μg of the polypeptide; at least 1, 10, or 100 mg of the polypeptide. A "purified preparation of cells", as used herein, refers to, in the case of plant or animal cells, an in vitro preparation of cells and not an entire intact plant or animal. In the case of cultured cells or microbial cells, it consists of a preparation of at least 10% and more preferably 50% of the subject cells. 14 A "treatment", as used herein, includes any therapeutic treatment, e.g., the administration of a therapeutic agent or substance, e.g., a drug. As used herein, the term "subject" refers to human and non-human animals. In preferred embodiments, the subject is a a human, e.g., person, e.g., a person having a sciellin related disorder. The term "non-human animals" of the invention includes all vertebrates, e.g., mammals and non-mammals, such as non-human primates, ruminants, birds, amphibians, reptiles. An "isolated" or " pure nucleic acid", e.g., a substantially pure DNA, is a nucleic acid which is one or both of: not immediately contiguous with either one or both of the sequences, e.g., coding sequences, with which it is immediately contiguous (i.e., one at the 5' end and one at the 3' end) in the naturally-occurring genome of the organism from which the nucleic acid is derived; or which is substantially free of a nucleic acid sequence with which it occurs in the organism from which the nucleic acid is derived. The term includes, for example, a recombinant DNA which is incorporated into a vector, e.g., into an autonomously replicating plasmid or virus, or into the genomic DNA of a prokaryote or eukaryote, or which exists as a separate molecule (e.g., a cDNA or a genomic DNA fragment produced by PCR or restriction endonuclease treatment) independent of other DNA sequences. Substantially pure DNA can also includes a recombinant DNA which is part of a hybrid gene encoding sequence. "Sequence identity or homology", as used herein, refers to the sequence similarity between two polypeptide molecules or between two nucleic acid molecules. When a position in both of the two compared sequences is occupied by the same base or amino acid monomer subunit, e.g., if a position in each of two DNA molecules is occupied by adenine, then the molecules are homologous or sequence identical at that position. The percent of homology or sequence identity between two sequences is a function of the number of matching or homologous identical positions shared by the two sequences divided by the number of positions compared x 100. For example, if 6 of 10, of the positions in two sequences are the same then the two sequences are 60% homologous or have 60% sequence identity. By way of example, the DNA sequences ATTGCC and TATGGC share 50% homology or sequence identity. Generally, a comparison is made when two sequences are aligned to give maximum homology. Unless otherwise specified "loop out regions", e.g., those arising from, from deletions or insertions in one of the sequences are counted as mismatches. The comparison of sequences and determination of percent homology between two sequences can be accomplished using a mathematical algorithim. Preferably, the alignment can be performed using the Clustal Method. Multiple alignment paramethers include GAP Penalty =10, Gap Length Penalty = 10. For 15 DNA alignments, the pairwise alignment paramenters can be Htuple=2, Gap penalty=5, Window=4, and Diagonal saved=4. For protein alignments, the pairwise alignment parameters can be Ktuple=l, Gap penalty=3, Window=5, and Diagonals Saved=5. Additional non- limiting example of a mathematical algorithim utilized for the comparison of sequences is the algorithm of Karlin and Altschul (1990) Proc. Natl. Acad. Sci. USA 87:2264-68, modified as in Karlin and Altschul (1993) Proc. Natl. Acad. Sci. USA 90:5873-77. Such an algorithm is incorporated into the NBLAST and XBLAST programs (version 2.0) of Altschul, et al. (1990) J. Mol. Biol. 215:403-10. BLAST nucleotide searches can be performed performed with the NBLAST program, score = 100, wordlength = 12 to obtain nucleotide sequences homologous to nucleic acid molecules of the invention. BLAST protein searches can be performed with the XBLAST program, score = 50, wordlength = 3 to obtain amino acid sequences homologous to protein molecules of the invention. To obtain gapped alignments for comparison purposes, Gapped BLAST can be utilized as described in Altschul et al., (1997) Nucleic Acids Research 25(17):3389-3402. When utilizing BLAST and Gapped BLAST programs, the default parameters of the respective programs (e.g., XBLAST and NBLAST) can be used. See http://www.ncbi.nlm.nih.gov. Another preferred, non-limiting example of a mathematical algorithim utilized for the comparison of sequences is the algorithm of Myers and Miller, CABIOS (1989). Such an algorithm is incorporated into the ALIGN program (version 2.0) which is part of the GCG sequence alignment software package. When utilizing the ALIGN program for comparing amino acid sequences, a PAM120 weight residue table, a gap length penalty of 12, and a gap penalty of 4 can be used. The terms "peptides", "proteins", and "polypeptides" are used interchangeably herein. As used herein, the term "transgene" means a nucleic acid sequence (encoding, e.g., one or more subject sciellin polypeptides), which is partly or entirely heterologous, i.e., foreign, to the transgenic animal or cell into which it is introduced, or, is homologous to an endogenous gene of the transgenic animal or cell into which it is introduced, but which is designed to be inserted, or is inserted, into the animal's genome in such a way as to alter the genome of the cell into which it is inserted (e.g., it is inserted at a location which differs from that of the natural gene or its insertion results in a knockout). A transgene can include one or more transcriptional regulatory sequences and any other nucleic acid, such as introns, that may be necessary for optimal expression of the selected nucleic acid, all operably linked to the selected nucleic acid, and may include an enhancer sequence. As used herein, the term "transgenic cell" refers to a cell containing a transgene. 16 As used herein, a "transgenic animal" is any animal in which one or more, and preferably essentially all, of the cells of the animal includes a transgene. The transgene can be introduced into the cell, directly or indirectly by introduction into a precursor of the cell, by way of deliberate genetic manipulation, such as by micro injection or by infection with a recombinant virus. This molecule may be integrated within a chromosome, or it may be extrachromosomally replicating DNA. As used herein, the term "tissue-specific promoter" means a DNA sequence that serves as a promoter, i.e., regulates expression of a selected DNA sequence operably linked to the promoter, and which effects expression of the selected DNA sequence in specific cells of a tissue, such as mammary tissue. The term also covers so-called "leaky" promoters, which regulate expression of a selected DNA primarily in one tissue, but cause expression in other tissues as well. "Unrelated to a sciellin amino acid or nucleic acid sequence" means having less than 30% sequence identity, less than 20% sequence identity, or, preferably, less than 10% homology with a naturally occuring sciellin sequence disclosed herein. A polypeptide has sciellin biological activity if it has one or more of the properties of sciellin disclosed herein. A polypeptide has biological activity if it is an antagonist, agonist, or super-agonist of a polypeptide having one of the properties of sciellin disclosed herein. "Misexpression", as used herein, refers to a non-wild type pattern of gene expression, at the RNA or protein level. It includes: expression at non-wild type levels, i.e., over or under expression; a pattern of expression that differs from wild type in terms of the time or stage at which the gene is expressed, e.g., increased or decreased expression (as compared with wild type) at a predetermined developmental period or stage; a pattern of expression that differs from wild type in terms of decreased expression (as compared with wild type) in a predetermined cell type or tissue type; a pattern of expression that differs from wild type in terms of the splicing size, amino acid sequence, post-transitional modification, or biological activity of the expressed polypeptide; a pattern of expression that differs from wild type in terms of the effect of an environmental stimulus or extracellular stimulus on expression of the gene, e.g., a pattern of increased or decreased expression (as compared with wild type) in the presence of an increase or decrease in the strength of the stimulus. Subject, as used herein, can refer to a mammal, e.g., a human, or to an experimental or animal or disease model. The subject can also be a non-human animal, e.g., a horse, cow, goat, or other domestic animal. 17 As described herein, one aspect of the invention features a substantially pure (or recombinant) nucleic acid which includes a nucleotide sequence encoding a sciellin polypeptide and/or equivalents of such nucleic acids. The term nucleic acid as used herein can include fragments and equivalents. The term equivalent refers to nucleotide sequences encoding functionally equivalent polypeptides. Equivalent nucleotide sequences will include sequences that differ by one or more nucleotide substitutions, additions or deletions, such as allelic variants, and include sequences that differ from the nucleotide sequences disclosed herein by degeneracy of the genetic code. The practice of the present invention will employ, unless otherwise indicated, conventional techniques of cell biology, cell culture, molecular biology, transgenic biology, microbiology, recombinant DNA, and immunology, which are within the skill of the art. Such techniques are described in the literature. See, for example, Molecular Cloning A Laboratory Manual, 2nd Ed., ed. by Sambrook, Fritsch and Maniatis (Cold Spring Harbor Laboratory Press: 1989); DNA Cloning, Volumes I and II (D. N. Glover ed., 1985); Oligonucleotide Synthesis (M. J. Gait ed., 1984); Mullis et al. U.S. Patent No: 4,683, 195 ; Nucleic Acid Hybridization (B. D. Hames & S. J. Higgins eds. 1984); Transcription And Translation (B. D. Hames & S. J. Higgins eds. 1984); Culture Of Animal Cells (R. I. Freshney, Alan R. Liss, Inc., 1987); Immobilized Cells And Enzymes (IRL Press, 1986); B. Perbal, A Practical Guide To Molecular Cloning (1984); the treatise, Methods In Enzymology (Academic Press, Inc., N.Y.); Gene Transfer Vectors For Mammalian Cells (J. H. Miller and M. P. Calos eds., 1987, Cold Spring Harbor Laboratory); Methods In Enzymology, Vols. 154 and 155 (Wu et al. eds.), Immunochemical Methods In Cell And Molecular Biology (Mayer and Walker, eds., Academic Press, London, 1987); Handbook Of Experimental Immunology, Volumes I-IV (D. M. Weir and C. C. Blackwell, eds., 1986); Manipulating the Mouse Embryo, (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1986). Other features and advantages of the invention will be apparent from the following detailed description, and from the claims. Detailed Description The drawings are briefly described. Figure 1 depicts a map of overlapping sciellin cDNA clones. The positions of the polyadenylation signals and poly(A)+ tails are indicated by arrowheads. 18 Figure 2 depicts the nucleotide sequence of sciellin cDNA and its predicted amino acid sequence. Figure 3 depicts the predicted sciellin amino acid sequence (SEQ ID NO:2). Sixteen (16) repeats of approximately twenty (20) residues are found from residue 231- 543. A single LIM domain of approximately fifty-six (56)m amino acids is located from residue 600-662. The sequences obtained from tryptic peptides are underlined, and cysteine residues are circled. Figure 4 depicts a hydropathy plot of all sixteen sciellin repeats from residue 231 to 543. The sciellin repeats are characterized by alternating hydrophobic and hydrophilic regions. Figure 5 depicts an alignment of sciellin LIM domain with several other LLM proteins. The consensus Cys and His residues are boxed. The relative positions of the LIM domains are indicated. The sequences are numbered from 1 to 8 as follows: 1 - sciellin [Homo sapiens] (SEQ ID NO:3) (Genbank Accession Number: AF045941), 2 - LLM-domain protein [Homo sapiens] (SEQ ID NO:4) (Genbank Accession Number: Y09538), 3 - Pl-A [Mus musculus] (SEQ ID NO:5) (Genbank Accession Number: U46687), 4 - zinc-finger domain-containing protein [Homo sapiens] (SEQ ID NO:6) (Genbank Accession Number: U90654), 5 - F28F5.2 gene product [C. elegans] (SEQ LD NO:7) (Genbank Accession Number: U00045), 6 - skeletal muscle LLM-protein FHL1 [Homo sapiens] (SEQ ID NO:8) (Genbank Accession Number: U60115), 7 - zyxin [Mus musculus] (SEQ ID NO:9) (Genbank Accession Number: Y07711), 8 - zyxin 2 [Homo sapiens] (SEQ ID NO:10) (Genbank Accession Number: X94991). Figure 6 depicts the results of chromosomal mapping of the sciellin gene to chromosome 13, band q22. Isolation and Cloning of Sciellin cDNA A human foreskin keratinocyte library packaged in lambda gtl 1 (Gerecke, D.R. et al. (1994) J. Biol. Chem. 269:11073-11080) was screened with a 1:50 dilution of the monoclonal Ab 34D11 specific for the cornified envelope precursor sciellin (Baden, H.P. et al. (1987) J. Invest. Dermatol. 89:454-459). Detection was performed using a 1 :500 dilution of goat anti-mouse HRP secondary antibody (I.C.N.) and chloronapthol (Biorad) according to standard protocols (Sambrook, j. et al. (1989) Molecular Cloning: A Laboratory Manual, 2nd Ed., Cold Spring Harbor Laboratory, Cold Spring Harbor, NY). Duplicating positive clones were analyzed by DNA sequencing and Northern blotting. Figure 1 is a graphic representation of overlapping sciellin cDNA clones. Four positive clones (clones SC4, SC5, SC6, and SC9) had overlapping sequence and each hybridized to two bands of 3.4 kb and 4.4 kb on a Northern blot of keratinocyte RNA. Clone 80A was 19 generated by 5'RACE from keratinocyte RNA. Clones 86C and 86A were generated by 3'RACE from keratinocyte RNA. All clones were sequenced except for the 3'-most 1 kb of clone 86A. Because these clones had overlapping sequence which was not represented in Genbank and they hybridized to keratinocyte mRNAs within the expected size range, they were suspected to represent the sciellin gene. The cDNA inserts from plaque-purified clones were amplified by PCR using primers made to the lambda gtl 1 cloning site flanking sequence (PF0169 : ACGACTCCTGGAGCCCGTCAGTAT (SEQ ID NO:l 1), and PFO170: ACCAACTGGTAATGGTAGCGACCG) (SEQ ID NO: 12) and subcloned into pCR2.1 (Invitrogen) or the EcoRI site of pBluescript KS+ (Stratagene). Overlapping cDNA clones which further extended the sequence were generated by 5' and 3' RACE reactions using nested primers and the 5' and 3' RACE System kits (Gibco BRL) according to manufacturer's protocols (Figure 1). The nested primers used for 5' RACE were MF79 (CTTCAGGGGTCACTTTGATGAGAT) (SEQ ID NO: 13) and MF80 (ATCAAGGCTCTGGCCCCTCGTAAT) (SEQ ID NO: 14). The nested primers used for 3' RACE wereMF85 (AACAATCAGAGCCAAGACTTGGAC) (SEQ IDNO:15) and MF86 (GAAACACTAATCGAGACCAGAACCTGG) (SEQ ID NO:16). DNA sequencing and computer analysis cDNAs which were subcloned into pBluescript, pGEM (Promega) or pCR2.1 were sequenced using the Thermo Sequenase Radiolabeled Terminator Cycle Sequencing Kit (Amersham) and 32p-ddNTPs. At least two independent cDNA subclones were sequenced to rule out Taq polymerase-generated nucleotide substitutions. In some cases, PCR product bands were sequenced directly by cycle sequencing after excision from a TAE- EtBr agarose gel and purification using the QIAquick Gel Extraction Kit (Qiagen). The sequencing project was analyzed using the Wisconsin Package Version 9.1 (Genetics Computer Group (GCG), Madison, Wise). Database comparisons were made using BLAST v2.0 (Altschul S.F. et al. (1977) Nucleic Acids Res. 25:3389-3402). The protein sequence was analyzed using the program PSORTII (Horton P. and Nakai K. (1997) Intelligent Systems for Molecular Biology 5 : 147- 152). The full-length cDNA sequence of sciellin is 2347 bp, including 86 bp of 5'- untranslated sequence and 257 bp of 3'-untranslated sequence (Figure 2). The nucleotide sequence surrounding the AUG initiator codon fits the consensus sequence for the initiation of translation by eukaryotic ribosomes (Kozak M. (1991) J Cell Biol 115:887- 903). The 2004 bp open reading frame encodes a protein of about 668 amino acids having a molecular mass of about 75.3 kD, which is close to the 82 kD previously reported for the 20 protein upon western blotting of cultured human keratinocyte extracts. The predicted isoelectric point of the unmodified protein as calculated from the sequence data was 10.09. Protein Isolation of Sciellin Sciellin protein was purified from human placenta using an immunoaffinity column made with polyclonal antiserum generated against a fusion protein. In brief, human placentas were dissected to collect only the amniotic membrane. The placentas were then frozen in liquid nitrogen, ground in a Waring blender (Waring Product Div., New Hartford, CT) and resuspended in citric acid monohydrate 0.1 M (100 ml for 50 g of tissue) containing 625 mg/1 of N-ethylmaleimide and 150 mg/1 of phenylmethylsulphonyl fluoride). The suspension was incubated at 4°C with stirring overnight. The soluble fraction was collected following centrifugation (30000 x g, for 30 min) and precipitated by adding 0.3 M NaCl final and raising the pH to 5.0. The precipitated proteins were collected following centrifugation (30000 x g, 30 min) and redissolved into buffer A: 150 mM NaCl, 2 raM EDTA, 10 mM Tris-HCl, pH 7.8 containing SDS 1%. At this point, the solution was boiled for 5 minutes, then 9 volumes of buffer A were added. The solution was then passed over a gelatin-Sepharose column (Pharmacia Fine Chemical, Piscataway, NJ) followed by an pAb SC4 immunoaffinity column. The columns were washed with PBS buffer and the elutions were done with 1M acetic acid. Protein Sequencing of Sciellin Protein sequencing was done according to Aebersold et al. (1987). Sciellin was eluted from the pAb SC4 affinity column and the fractions were concentrated by precipitation with 9 volumes of ethanol 100%. The material was then electrophoresed on a 7.5% SDS-page, stained briefly with Coomassie Blue 0.2%, destained in acetic acid 7%, methanol 10%. The band corresponding to sciellin was excised from the gel, washed in H 2 0 and kept in acetonitrile 50% until sequenced. The N-terminal amino acid was blocked. Sequence was obtained by mass spectrometry from two tryptic peptides. Briefly, the band was incubated with trypsin and the resulting peptides were separated by HPLC and analyzed by matrix-assisted laser desorption time-of-flight mass spectrometry performed on a Finnigen Lasermat 2000 (Hemel, UK) (Chait B.T. and Kent S.B. (1992) Science 257:1885-1894). To obtain the N- terminal sequence, the material was blotted on a PVDF membrane (Bio-Rad Laboratories, Richmond, CA) stained with Ponceau-S and the band corresponding to sciellin was sequenced on the sequenator. The peptide sequences SSEQGLDEHINVSPK (SEQ ID NO:25) and QPLENLQAGDSIWIYR (SEQ ID NO:26) matched perfectly with the translated cDNA sequence from residues 443-457 and 635-650 (Figure 3). 21 Structural Analysis of Sciellin The amino acid sequence of sciellin is shown in Figures 2-3 and is 668 residues long. Comparison of the sciellin protein sequence with the Genbank database using the program BLAST showed that sciellin was a unique protein. The protein was generally hydrophilic and did not contain any regions likely to form either a signal peptide or a transmembrane domain, consistent with its cytoplasmic localization by immunohistochemistry. The deduced sciellin protein sequence can be divided into three domains based upon potential structure and function predictions (such as those generated by the program Plotstructure (GCG)): an amino domain, a central domain comprised of repeating units, and a carboxyl domain containing a single LIM motif. Proline residues were evenly distributed throughout the molecule, except for an enriched "hinge" region before the first repeat unit, starting at residue 165. Comparison of the encoded protein against the PROSITE database (Bairoch A. et al. ( 1997) Nucleic Acids Res 25:217-221 ) revealed that sciellin has sixteen potential N- glycosylation sites, five potential myristylation sites and thirty-five potential phosphorylation sites, including three cAMP- and cGMP-dependent protein kinase phosphorylation sites, twenty-two protein kinase C phosphorylation sites, nine casein kinase II phosphorylation sites, and one tyrosine kinase phosphorylation site. Western blots of large 2D gels of cultured keratinocyte extracts using 34dl 1 showed bands of 85.7 kD (PI 8.32), 86.1 kD (PI 8.72), 86.1 kD (PI 8.86) and 86.2 kD (PI 9.08) (Human Keratinocytes-NEPHGE Database, Danish Centre for Human Genome Research, http://biobase.dk cgi-bin/celis). Post-translational phosphorylation of sciellin may explain the difference between the observed and calculated pi and M r values of the protein. Analysis of the sciellin protein sequence with the subcellular localization site prediction program PSORTII (Horton P. and Nakai K. (1997) Intelligent Systems for Molecular Biology 5:147-152) suggested that sciellin may be a nuclear protein, based upon the presence of four potential nuclear localization signals. However we have never found sciellin located in the nucleus by immunofluorescent staining of keratinocyte cell cultures, which presumably contain cells in all phases of the cell cycle (Champliaud M.F. et al. (1998) J. Invest. Dermtol. In Press). The program PEST-FIND (Rogers S. et al. (1986) Science 234:364-368) identified a potential PEST sequence at 326-339. PEST sequences are rich in Pro (P), Glu (E), Ser (S) and Thr (T) and are often flanked by clusters of positively charged residues. PEST sequences are believed to confer susceptibility to rapid intracellular proteolysis, resulting in an intracellular half life of less than two hours. 22 Analysis of Central Domain Repeats The sciellin repeats are about 20 residues long and are characterized by a striking pattern of alternating stretches of hydrophobicity and hydrophilicity on hydropathy plots. There were 16 inexact repeat units from residues 231 to 543 of which 12 were 20 amino acids in length. The fourth, seventh, eighth, and tenth amino acid residues in the repeats were mainly hydrophobic, the fifth, ninth, thirteenth, and sixteenth charged and the second, ninth and sixteenth rich in Gin and Lys. The overall percentage of Gin and Lys in the repeat region of the molecule was identical to the remainder of the sequence. The twelfth position was rich in Pro which would allow for flexibility in the approximate center of the repeats. In plots of relative hydrophobicity, the repeats show up as having a pattern of alternating hydrophobic and hydrophilic stretches (Figure 4). The hydrophobic stretches are predicted to form beta structures of 5-7 residues, terminating at the Pro residue. The hydrophobic stretches are 5-7 residues long and are predicted to form beta sheets. This is very similar to the parallel beta helix structure which has been described for the P22 tailspike protein and pectate lyase C (Yoder, M.D. et al. (1993) Science 260: 1503- 1507). The crystal structure of the P22 tailspike protein demonstrates that each subunit of the homotrimer contains a large parallel beta helix. The beta helix of each strand is formed by short parallel beta sheets coiled into a large right-handed helix, similar to a rope coiled into a tidy cylinder. Each turn of the beta helix is comprised of between 16 and 22 residues. The hydrophobic side chains stack into the helix interior so the beta strands are arranged in stacks like rungs on a ladder. The charged and polar residues form a hydrophilic interface between adjacent beta helices in the homotrimer. The carboxyl domain of P22 tailspike protein is important for the association of monomers. By analogy sciellin could form homotrimeric beta helices which become cross-linked by transglutaminase into very rigid protein girders, lending structural support to the cornified envelopes of stratum corneum cells. The presence of a PEST sequence could ensure that monomeric sciellin is rapidly degraded in the absence of crosslinking transglutaminases. The repeats surrounding the amino acids LIKV were found in the repeat region of sciellin as shown in Figure 3. The repeats involving G were few and short and NQG was found three times and GQS twice. However, the repeat GQDPVK reported as a transglutaminase substrate in elaphin and the repeats AQEPVK and GQDKVK found to link elaphin to loricrin were not observed in sciellin. Also the sequence around glutamine 496 (EQQV) in involucrin, the preferential site of labeling by transglutaminase was not present in sciellin. Analysis ofCarboxy Terminal LIM Motif 23 The carboxyl domain of sciellin contained a single LLM motif consensus sequence (Figure 5). The LIM domain has a characteristic arrangement of Cys and His residues which coordinate zinc ions into structures that function as protein-binding interfaces (Schmeichel K.L. and Beckerie M.C. (1994) Cell 79:211-219). In particular, the consensus sequence of the LIM motiff is as follows: CX 2 CX, 6-23 HX 2 CX 2 CX 2 CX 16-21 CX 2-3 (C,H,D) (SEQ LD NO: 17). LIM motiffs have been identified in a number of proteins with diverse functions and subcellular locations, including transcription factors, and components of adhesion plaques and the actin-based cytoskeleton. A single LIM domain of roughly 56 amino acids folds into two independent structural domains, with the conserved Cys and His residues coordinating two Zinc ions (Sanchez-Garcia I. and Rabbitts T.H. (1994) Trends in Genet. 10:315-320). All nine Cys residues in sciellin were found in this carboxyl domain, starting at residue 601. These were not expected to form interchain crosslinks because sciellin has the same mobility in SDS-PAGE with and without treatment with a reducing agent. Proteins containing LIM domains have been classified according to the number and position of LIM domains and the presence of other functional motifs, such as homeodomains (Taira M. et al. (1995) Trends in Genet. 11 :431-432). Sciellin is a group 3 LLM protein as it has a single LIM domain in its carboxyl end. Other group 3 LIM proteins are known to interact with the cytoskeleton and might function in cell adhesiveness, intracellular signalling, and defining cell shape. This group includes zyxin, a low abundance phosphoprotein concentrated at adhesion plaques and associated with actin filament arrays (Beckerie M.C. (1986) J. Cell Biol. 103:1679-1687). Zyxin contains three LIM domains in its carboxyl end and these have been shown to mediate zyxin binding to CRP (Crawford A.W. et al. (1994) J. Cell 5 o/.124: 117- 127), which also contains two LIM domains. Zyxin binds a-actinin through a different functional domain. AbLIM (Roof D.J. et al. 1997) J. Cell Biol. 138:575-588) is an actin-binding LIM protein which localizes to adherens junctions in the retinal outer limiting membrane. Enigma is a LIM protein which binds to insulin receptors via a LIM domain recognizing a Tyr-containing tight turn structure on the receptor (Wu R.Y. and Gill G.N. (1994) J. Biol. Chem. 40:25082-25090). Individual LIM domains can display distinct binding specificities. The conserved Cys and His residues coordinate zinc ions, folding the LIM domain into two loops. The sequences of the intervening loops may confer binding specificity. This distinct partner preference of a single LIM domain has been demonstrated in the protein zyxin. One of the three zyxin LIM domains is necessary and sufficient to direct specific binding of zyxin with CRP, but not with other LIM domain-containing proteins (Schmeichel K.L. and Beckerie M.C. (1994) Cell 79:211-219). It has also been demonstrated that a single LIM domain can interact with two other LIM domains as an adaptor element to promote the 24 assembly and targeting of multiprotein complexes (Arber S. and Caroni P. (1996) Genes andDevel 10:289-300). The LIM domain of sciellin may be involved in homotypic or heterotypic associations and may function to localize sciellin to the cornified envelope, mediate the assembly of multiprotein structural complexes or regulate the activity of its protein partners. Northern Blot Analysis of Sciellin mRNA Expression Total RNA was isolated using the RNeasy (Qiagen) from human foreskin keratinocytes cultured in high calcium medium and also from post-partum human placentas, carefully dissected into amnion, chorion, villous and non-villous layers. 25 μg of RNA per lane were electrophoresed through a 1% agarose gel, blotted onto nitrocellulose and hybridized using the NorthernMax kit (Ambion) according to the enclosed protocols. 32P-dCTP-labelled probes were generated from gel-purified DNA using the Rediprime Random Primer Labelling Kit (Amersham). The probe for the keratinocyte and placenta blot was generated from the EcoRI insert of cDNA clone SC4. The probe for the 4.4 kb sciellin message was generated by 3' RACE from clone 86A using primer MF 175 (GCAAGCGGGTGATAGTATTTGGAT) (SEQ ID NO: 18). Human Normal Tissue Blots I and II (Northern Territory Total RNA Blots, Invitrogen) were hybridized with a 32P-UTP-labelled antisense RNA probe made from pP0325 (Sciellin cDNA nt. 830-2310 subcloned into pBluescript II KS+) using the RNA Transcription Kit (Stratagene). The blots were hybridized and washed under stringent conditions using the NorthernMax Buffer System (Ambion), according to the supplied protocols. Human sciellin cDNA probes hybridized to two messages of about 3.4 and 4.4 kb on Northern blots of both poly(A)+ RNA from stratified squamous epithelial tissues and amnion. A Northern blot of poly(A)+ RNA hybridized with a random-primed DNA probe demonstrated that human sciellin mRNAs are expressed in cultured keratinocytes and amnion, but not in carefully dissected villous chorion, decidua basalis or smooth chorion. Human Multiple Tissue Northerns (Invitrogen) were hybridized with an antisense RNA probe made from the sciellin cDNA clone pP0325. Sciellin mRNA shows limited expression in human tissues. Strong expression is detected in the esophagus, but not in stomach, intestine, colon, uterus, placenta, bladder, or adipose tissue or in heart, brain, kidney, liver, lung, pancreas, spleen, or muscle. The reported sequence is believed to represent the short message. When PCR primers made to the sequences surrounding the initiator methionine and stop codons were used to amplify the complete coding region of the sciellin cDNA, only a single band was ever found. Both monoclonal and polyclonal antibodies recognized a single band on a 25 Western blot, suggesting the difference in message sizes is not in the coding region. Multiple attempts at 5' RACE, using nested PCR primers which were derived from several different regions within the coding sequence always gave a single band corresponding in size to the reported 5' end. Multiple attempts at 3' RACE, also using nested primers from different regions, resulted in two bands, corresponding to the reported 3' end and one which was 1 kb longer. The larger band, cDNA 86A (Figure 1), was difficult to subclone and when sequenced directly from the PCR product gave a sequence identical to the short form clone 86C, including a polyadenylation signal and a poly(A)+ tail in the same position, and unreadable sequence 3' of this tail. It is not known if clone 86A has an additional poly(A)+ tail at its 3'-most end as this region remains unsequenced, but the utilization of alternative transcription termination signals is a well documented phenomenon (Pikkarainen T. et al. (1988) JBiol. Chem. 263:6751-6758). When a portion of cDNA 86A (2.0-3.35 kb, Figure 1) was used as a Northern probe it hybridized to both the 3.4 and 4.4 kb bands, although the 4.4 kb band signal intensity was much stronger than the 3.4 kb band intensity. Assuming that the size difference in mRNA bands is due to an additional 1 kb at the 3' end, one would expect that only 0.35 kb of the 86A probe could hybridize with the 3.4 kb band and all 1.35 kb of the probe could hybridize with the 4.4. kb band, resulting in significantly different hybridization intensities. This is consistent with the observed 86A Northern band intensities. Northern probes derived from anywhere else in the sciellin cDNA hybridized to the two bands with roughly equal intensity. Therefore, the two message sizes observed for sciellin can be explained by the presence of two transcription termination signals which are 1 kb apart in the 3 '-untranslated region. Tissue Distribution of Sciellin mRNA Detected hv In Situ Hybridization Sense and antisense digoxigenin-RNA probes were transcribed from the plasmids pPOSC5 and pPOK5 using the RNA Transcription Kit (Stratagene) and DIG RNA labelling mix (Boehringer Mannheim Biochemicals). The RT-PCR amplification product of the keratin K5 mRNA from nt. 73-1076 (Lersch R. and Fuchs E. (1988) Mol. Cell. Biol 8:486-493) was subcloned into pBluescript KS+ to create pPOK5, and clone SC5 was subloned into pBluescript KS+ to create pPOSC5. Ten (10) micron sections were cut from human foreskin which had been fixed in 4% paraformaldehyde and frozen in O.C.T. Compound (TissueTek). Tissue sections were hybridized overnight at 60°C in a 50% formamide hybridization buffer. DIG was detected using anti-digoxigenin-alkaline phosphatase FAb fragments (Boehringer Mannheim Biochemicals) according to manufacturer's protocols. In situ hybridization of human foreskin sections with a sciellin antisense probe made from clone SC5 showed that sciellin mRNA is expressed in the upper stratum 26 spinosum and the stratum granulosum. In situ hybridization with a control keratin 5 antisense probe showed that the K5 mRNA is expressed primarily in the basal keratinocytes. Neither sciellin nor K5 sense probes hybridized to foreskin sections. Expression of Recombinant Sciellin Sciellin cDNA, corresponding to cDNA clone SC4 (Figure 1), nucleotides 1120- 1736, was amplified by RT-PCR from human differentiated keratinocyte RNA using adaptor primers PF0237 (GTTCCATATGGAAAATACCACTGGAAAAAAAGAC) (SEQ ID NO: 19) and PF0238 (TCCCGCGGTTACTTGGCTCCAGTGTTAGAGCT) (SEQ LD NO:20) and subcloned into the Ndel and SacII sites of the T7 expression vector pET-15b (Novagen), which had been modified by replacement of the BamHI site with a SacII site (a gift of Manuel Koch). The resulting fusion protein construct, pP0324, was transformed into Novablue(DE3) competent cells (Novagen) and the fusion protein SC4 was expressed and purified using the His-Bind Resin and His-Bind Buffer System (Novagen) according to manufacturer's protocols. Polyclonal antiserum was raised in two rabbits by Charles River Pharmservices using 0.1 mg of SC4 fusion protein per injection. Production of a Sciellin Specific Antibody and Immunohistochemical Localization For Western blot analysis, a mouse monoclonal antibody to sciellin (34D11) and two polyclonal antibodies against sciellin were used. To prepare the polyclonal antibodies, rabbits were immunized with a sciellin fusion protein expressed from the equivalent of cDNA clone SC4 using the pET system (Novagen). SDS-PAGE analysis of sciellin and electrophoretic transfer of protein to nitrocellulose with immunoblot analysis were performed as described in Laemmli, 1970 and Lunstrum et al., 1986, respectively. The appropriate HRP -conjugated IgG (ICN) was used as the secondary antibody. The polyclonal sera of both rabbits identified a band of 84 kD by Western blotting of lysis buffer extracts of cultured human keratinocytes, while the preimmune sera did not react. This band was identical in mobility to the sciellin band identified by monoclonal 34dl 1. Polyclonal antisera raised against a fusion protein expressed from the sciellin cDNA stained tissue sections by indirect immunofluorescence in a pattern identical to the pattern generated using the sciellin monoclonal antibody. Immunohistochemical analysis was performed following standard techniques. The appropriate FITC-conjugated secondary antibody (Cappel) was used for indirect immunofluorescence on 10 mm sections fixed with acetone at -20°C for 10 minutes. Immuno fluorescent staining of normal human body and plantar skin using the SC4 antibody showed peripheral staining of keratinocytes in the granular and upper spinous layers of epidermis and the inner layer of the isthmus of 27 the hair follicle, identical to the pattern observed with 34dl 1. Bovine and newborn mouse skin gave a similar pattern of staining. The stratified epithelium of the tongue, oral cavity, esophagus, vagina, bladder, ureter and cornea also reacted with the antibody. The simple epithelium of mouse and bovine trachea, lung, kidney, liver, and small and large intestine, as well as non-epithelial tissues, did not stain with the antibody. These findings are identical to the previously reported tissue distribution of sciellin using 34dl 1. The exception was staining of bovine and human amnion, in which sciellin presumably plays a role in barrier function. Chromosomal Localization and Radiation Hybrid Mapping of the Sciellin Gene A 1.45 kb cDNA probe, ρP0325, was biotinylated with dATP using the BRL BioNick labeling kit (15°C, 1 hr) (Heng H.H.Q. et al. (1992) Proc Natl Acad Sci USA 89:9509-9513). The procedure for FISH detection was performed according to Heng et al. (1992), supra, and Heng, H.H.Q. et al. (1992) Proc Natl Acad Sci USA 89:9509-9513. Briefly, slides were baked at 55°C for 1 hour. After RNase treatment, the slides were denatured in 70% formamide in 2x SSC for 2 min. at 70°C followed by dehydration with ethanol. Probes were denatured at 75°C for 5 min. in a hybridization mix consisting of 50% formamide and 10% dextran sulfate and loaded on the denatured chromosomal slides. After overnight hybridization, slides were washed and detected as well as amplified. FISH signals and the DAPI banding pattern were recorded separately by taking photographs, and the assignment of the FISH mapping data with chromosomal bands was achieved by superimposing FISH signals with DAPI banded chromosomes (Heng, H.H.Q., and Tsui, L.-C. (1993) Chromosoma 102:325-332). Based on FISH mapping, the sciellin gene was located to chromosome 13, band q22. Under the conditions used, probe pP0325 hybridized with 76% efficiency (among 100 mitotic figures, 76 showed signals on one pair of the chromosomes). Since DAPI banding was used to identify the specific chromosome, the assignment between signal from probe and the long arm of chromosome 13 was obtained. The detailed position was further determined based on the summary from 10 photos (Figure 6). There was no additional locus picked by FISH detection under the conditions used. To further characterized the Sciellin gene chromosomal location, the Stanford G3 Radiation Hybrid Mapping Panel (Research Genetics) was screened by PCR using two primer pairs derived from the sciellin genomic DNA sequence, MF122 (TTTGGAACCTTGGTTACTTCT) (SEQ ID NO:21) and MF124 (GGCTCTGAGACTAAAATAATGTCT) (SEQ ID NO:22), and MF79 (CTTCAGGGGTCACTTTGATGAGAT) (SEQ ID NO:23) and PFO280 (AGCGGCCAAATGGCTCTGAGAC) (SEQ ID NO:24). The G3 panel was also screened 28 using two STS markers which were linked to Clouston's hidrotic ectodermal dysplasia (Clouston's HED), D13S141 and D13S175 (Research Genetics). These markers were ordered relative to the SHGC framework markers of the G3 RH map v2.0 using the statistical analysis program RHMAP (http://shgc-www.stanford.edu). A search of the OMIM database for disorders which mapped in the proximity of chromosome 13 band q22, and which had a skin, nail and hair phenotype, as indicated by the immunofluorescent localization of sciellin, suggested that Clouston's HED could be a candidate disease for a disrupted sciellin gene. The phenotype of Clouston's HED includes dystrophic nails, hair defects, and palmoplantar hyperkeratosis. The gene disrupted in Clouston's HED was also mapped to chromosome band 13q and linkage analysis showed it was linked to the STS markers D13S175 and D13S141 (Kibar Z. et al. (1996) Hum. Mol. Genet. 5:543-547). Radiation hybrid mapping was used to determine if the sciellin gene also showed linkage to these same STS markers which are linked to HED. The Stanford G3 Radiation Hybrid Mapping Panel (Stewart E.A. et al. (1997) Genome Res. 7:422-433) was screened by PCR with markers derived from the sciellin gene, MF122/MF124 and MF79/PFO280, as well as the markers which were shown to be linked to Clouston's HED. MF122/MF124 was linked to the framework marker WI-457 at a distance of 14.56 cR and a L.O.D. score of 7.77, and MF79/PFO280 was linked to the framework marker WI-457 at a distance of 23.69 cR and a L.O.D. score of 5.86. D13S175 was linked to the framework marker SHGC-6104 and D13S141 was linked to the framework marker SHGC-37580 at a distance of 66.1 cR and a L.O.D. of 3.99. The sciellin gene did not show linkage to the STS markers which were previously shown to be linked to Clouston's HED, therefore it is unlikely that HED is a candidate disease for a disrupted sciellin gene. Analogs of Sciellin Analogs can differ from naturally occurring sciellin in amino acid sequence or in ways that do not involve sequence, or both. Non-sequence modifications include in vivo or in vitro chemical derivatization of sciellin. Non-sequence modifications include changes in acetylation, methylation, phosphorylation, carboxylation, or glycosylation. Preferred analogs include sciellin (or biologically active fragments thereof) whose sequences differ from the wild-type sequence by one or more conservative amino acid substitutions or by one or more non-conservative amino acid substitutions, deletions, or insertions which do not abolish the sciellin biological activity. Conservative substitutions typically include the substitution of one amino acid for another with similar characteristics, e.g., substitutions within the following groups: valine, glycine; glycine, alanine; valine, isoleucine, leucine; aspartic acid, glutamic acid; asparagine, glutamine; serine, threonine; 29 lysine, arginine; and phenylalanine, tyrosine. Other conservative substitutions can be taken from the table below. TABLE 1 CONSERVATIVE AMINO ACID REPLACEMENTS For Amino Code Replace with any of Acid Alanine A D-Ala, Gly, beta-Ala, L-Cys, D-Cys Arginine R D-Arg, Lys, D-Lys, homo-Arg, D- homo-Arg, Met, He, D-Met, D-Ile, Orn, D-Orn Asparagine N D-Asn, Asp, D-Asp, Glu, D-Glu, Gin, D-Gln Aspartic Acid D D-Asp, D-Asn, Asn, Glu, D-Glu, Gin, D-Gln Cysteine C D-Cys, S-Me-Cys, Met, D-Met, Thr, D-Thr Glutamine Q D-Gln, Asn, D-Asn, Glu, D-Glu, Asp, D-Asp Glutamic Acid E D-Glu, D-Asp, Asp, Asn, D-Asn, Gin, D-Gln Glycine G Ala, D-Ala, Pro, D-Pro, β-Ala Acp Isoleucine I D-Ile, Val, D-Val, Leu, D-Leu, Met, D-Met Leucine L D-Leu, Val, D-Val, Leu, D-Leu, Met, D-Met 30 Lysine K D-Lys, Arg, D-Arg, homo-Arg, D- homo-Arg, Met, D-Met, He, D-Ile, Orn, D-Orn Methionine M D-Met, S-Me-Cys, lie, D-Ile, Leu, D-Leu, Val, D-Val Phenylalanine F D-Phe, Tyr, D-Thr, L-Dopa, His, D- His, T , D-Trp, Trans-3,4, or 5- phenylproline, cis-3,4, or 5-phenylproline Proline P D-Pro, L-I-thioazolidine-4- carboxylic acid, D-or L-l- oxazolidine-4-carboxylic acid Seπne S D-Ser, Thr, D-Thr, allo-Thr, Met, D-Met, Met(O), D-Met(O), L-Cys, D- Cys Threonine T D-Thr, Ser, D-Ser, allo-Thr, Met, D-Met, Met(O), D-Met(O), Val, D-Val Tyrosine Y D-Tyr, Phe, D-Phe, L-Dopa, His, D- His Valine V D-Val, Leu, D-Leu, He, D-Ile, Met, D-Met Other analogs within the invention are those with modifications which increase peptide stability; such analogs may contain, for example, one or more non-peptide bonds (which replace the peptide bonds) in the peptide sequence. Also included are: analogs that include residues other than naturally occurring L-amino acids, e.g., D-amino acids or non- naturally occurring or synthetic amino acids, e.g., β or γ amino acids; and cyclic analogs. Gene Therapy The gene constructs of the invention can also be used as a part of a gene therapy protocol to deliver nucleic acids encoding either an agonistic or antagonistic form of a sciellin polypeptide. The invention features expression vectors for in vivo transfection and 31 expression of a sciellin polypeptide in particular cell types so as to reconstitute the function of, or alternatively, antagonize the function of a sciellin polypeptide in a cell in which that polypeptide is misexpressed. Expression constructs of sciellin polypeptides, may be administered in any biologically effective carrier, e.g. any formulation or composition capable of effectively delivering the sciellin gene to cells in vivo. Approaches include insertion of the subject gene in viral vectors including recombinant retro viruses, adenovirus, adeno-associated virus, and herpes simplex virus- 1, or recombinant bacterial or eukaryotic plasmids. Viral vectors transfect cells directly; plasmid DNA can be delivered with the help of, for example, cationic liposomes (lipofectin) or derivatized (e.g. antibody conjugated), polylysine conjugates, gramacidin S, artificial viral envelopes or other such intracellular carriers, as well as direct injection of the gene construct or CaP04 precipitation carried out in vivo. A preferred approach for in vivo introduction of nucleic acid into a cell is by use of a viral vector containing nucleic acid, e.g. a cDNA, encoding a sciellin polypeptide. Infection of cells with a viral vector has the advantage that a large proportion of the targeted cells can receive the nucleic acid. Additionally, molecules encoded within the viral vector, e.g., by a cDNA contained in the viral vector, are expressed efficiently in cells which have taken up viral vector nucleic acid. Retrovirus vectors and adeno-associated virus vectors can be used as a recombinant gene delivery system for the transfer of exogenous genes in vivo, particularly into humans. These vectors provide efficient delivery of genes into cells, and the transferred nucleic acids are stably integrated into the chromosomal DNA of the host. The development of specialized cell lines (termed "packaging cells") which produce only replication-defective retroviruses has increased the utility of retroviruses for gene therapy, and defective retroviruses are characterized for use in gene transfer for gene therapy purposes (for a review see Miller, A.D. (1990) Blood 76:271). A replication defective retrovirus can be packaged into virions which can be used to infect a target cell through the use of a helper virus by standard techniques. Protocols for producing recombinant retroviruses and for infecting cells in vitro or in vivo with such viruses can be found in Current Protocols in Molecular Biology. Ausubel, F.M. et al. (eds.) Greene Publishing Associates, (1989), Sections 9.10-9.14 and other standard laboratory manuals. Examples of suitable retroviruses include pLJ, pZIP, pWE and pEM which are known to those skilled in the art. Examples of suitable packaging virus lines for preparing both ecotropic and amphotropic retroviral systems include ψCrip, ψCre, ψ2 and ψAm. Retroviruses have been used to introduce a variety of genes into many different cell types, including epithelial cells, in vitro and/or in vivo (see for example Eglitis, et al. (1985) Science 230:1395-1398; Danos and Mulligan (1988) Proc. Natl. Acad. Sci. USA 85:6460-6464; Wilson et al. (1988) Proc. 32 Natl. Acad. Sci. USA 85:3014-3018; Armentano et al. (1990) Proc. Natl. Acad. Sci. USA 87:6141-6145; Huber et al. (1991) Proc. Natl. Acad. Sci. USA 88:8039-8043; Ferry et al. (1991) Proc. Natl. Acad. Sci. USA 88:8377-8381; Chowdhury et al. (1991) Science 254:1802-1805; van Beusechem et al. (1992) Proc. Natl. Acad. Sci. USA 89:7640-7644; Kay et al. (1992) Human Gene Therapy 3:641-647; Dai et al. (1992) Proc. Natl. Acad. Sci. USA 89:10892-10895; Hwu et al. (1993) J. Immunol. 150:4104-4115; U.S. Patent No. 4,868,116; U.S. Patent No. 4,980,286; PCT Application WO 89/07136; PCT Application WO 89/02468; PCT Application WO 89/05345; and PCT Application WO 92/07573). Another viral gene delivery system useful in the present invention utilizes adenovirus-derived vectors. The genome of an adenovirus can be manipulated such that it encodes and expresses a gene product of interest but is inactivated in terms of its ability to replicate in a normal lytic viral life cycle. See, for example, Berkner et al. (1988) BioTechniques 6:616; Rosenfeld et al. (1991) Science 252:431-434; and Rosenfeld et al. (1992) Cell 68:143-155. Suitable adenoviral vectors derived from the adenovirus strain Ad type 5 dl324 or other strains of adenovirus (e.g., Ad2, Ad3, Ad7 etc.) are known to those skilled in the art. Recombinant adenoviruses can be advantageous in certain circumstances in that they are not capable of infecting nondividing cells and can be used to infect a wide variety of cell types, including epithelial cells (Rosenfeld et al. (1992) cited supra). Furthermore, the virus particle is relatively stable and amenable to purification and concentration, and as above, can be modified so as to affect the spectrum of infectivity. Additionally, introduced adenoviral DNA (and foreign DNA contained therein) is not integrated into the genome of a host cell but remains episomal, thereby avoiding potential problems that can occur as a result of insertional mutagenesis in situations where introduced DNA becomes integrated into the host genome (e.g., retroviral DNA). Moreover, the carrying capacity of the adenoviral genome for foreign DNA is large (up to 8 kilobases) relative to other gene delivery vectors (Berkner et al. cited supra; Haj-Ahmand and Graham (1986) J. Virol. 57:267). Yet another viral vector system useful for delivery of the subject gene is the adeno- associated virus (AAV). Adeno-associated virus is a naturally occurring defective virus that requires another virus, such as an adenovirus or a herpes virus, as a helper virus for efficient replication and a productive life cycle. (For a review see Muzyczka et al. Curr. Topics in Micro, and Immunol. (1992) 158:97-129). It is also one of the few viruses that may integrate its DNA into non-dividing cells, and exhibits a high frequency of stable integration (see for example Flotte et al. (1992) Am. J. Respir. Cell. Mol. Biol. 7:349-356; Samulski et al. (1989) J. Virol. 63:3822-3828; and McLaughlin et al. (1989) J. Virol. 62:1963-1973). Vectors containing as little as 300 base pairs of AAV can be packaged and can integrate. Space for exogenous DNA is limited to about 4.5 kb. An AAV vector such 33 as that described in Tratschin et al. ( 1985) Mol. Cell. Biol. 5:3251 -3260 can be used to introduce DNA into cells. A variety of nucleic acids have been introduced into different cell types using AAV vectors (see for example Hermonat et al. (1984) Proc. Natl. Acad. Sci. USA 81:6466-6470; Tratschin et al. (1985) Mol. Cell. Biol. 4:2072-2081; Wondisford et al. (1988) Mol. Endocrinol. 2:32-39; Tratschin et al. (1984) J. Virol. 51:611-619; and Flotte et al. (1993) J. Biol. Chem. 268:3781-3790). In addition to viral transfer methods, such as those illustrated above, non- viral methods can also be employed to cause expression of a sciellin polypeptide in the tissue of an animal. Most nonviral methods of gene transfer rely on normal mechanisms used by mammalian cells for the uptake and intracellular transport of macromolecules. In preferred embodiments, non- viral gene delivery systems of the present invention rely on endocytic pathways for the uptake of the subject sciellin gene by the targeted cell. Exemplary gene delivery systems of this type include liposomal derived systems, poly-lysine conjugates, and artificial viral envelopes. In a representative embodiment, a gene encoding a sciellin polypeptide can be entrapped in liposomes bearing positive charges on their surface (e.g., lipofectins) and (optionally) which are tagged with antibodies against cell surface antigens of the target tissue (Mizuno et al. (1992) No Shinkei Geka 20:547-551; PCT publication WO91/06309; Japanese patent application 1047381; and European patent publication EP-A-43075). In clinical settings, the gene delivery systems for the therapeutic sciellin gene can be introduced into a patient by any of a number of methods, each of which is familiar in the art. For instance, a pharmaceutical preparation of the gene delivery system can be introduced systemically, e.g. by intravenous injection, and specific transduction of the protein in the target cells occurs predominantly from specificity of transfection provided by the gene delivery vehicle, cell-type or tissue-type expression due to the transcriptional regulatory sequences controlling expression of the receptor gene, or a combination thereof. In other embodiments, initial delivery of the recombinant gene is more limited with introduction into the animal being quite localized. For example, the gene delivery vehicle can be introduced by catheter (see U.S. Patent 5,328,470) or by Stereotactic injection (e.g. Chen et al. (1994) PNAS 91: 3054-3057). The pharmaceutical preparation of the gene therapy construct can consist essentially of the gene delivery system in an acceptable diluent, or can comprise a slow release matrix in which the gene delivery vehicle is imbedded. Alternatively, where the complete gene delivery system can be produced in tact from recombinant cells, e.g. retroviral vectors, the pharmaceutical preparation can comprise one or more cells which produce the gene delivery system. 34 Transgenic Animals The invention includes transgenic animals which include cells (of that animal) which contain a sciellin transgene and which preferably (though optionally) express (or misexpress) an endogenous or exogenous sciellin gene in one or more cells in the animal. The sciellin transgene can encode the wild-type form of the protein, or can encode homologs thereof, including both agonists and antagonists, as well as antisense constructs. In preferred embodiments, the expression of the transgene is restricted to specific subsets of cells, or tissues utilizing, for example, cis-acting sequences that control expression in the desired pattern. Tissue-specific regulatory sequences and conditional regulatory sequences can be used to control expression of the transgene in certain spatial patterns, e.g., to restrict production to the milk or other secreted product of the animal. Production of Fragments and Analogs Generation of Fragments Fragments of a protein can be produced in several ways, e.g., recombinantly, by proteolytic digestion, or by chemical synthesis. Internal or terminal fragments of a polypeptide can be generated by removing one or more nucleotides from one end (for a terminal fragment) or both ends (for an internal fragment) of a nucleic acid which encodes the polypeptide. Expression of the mutagenized DNA produces polypeptide fragments. Digestion with "end-nibbling" endonucleases can thus generate DNA's which encode an array of fragments. DNA's which encode fragments of a protein can also be generated by random shearing, restriction digestion or a combination of the above-discussed methods. Fragments can also be chemically synthesized using techniques known in the art such as conventional Merrifield solid phase f-Moc or t-Boc chemistry. For example, peptides of the present invention may be arbitrarily divided into fragments of desired length with no overlap of the fragments, or divided into overlapping fragments of a desired length. Generation of Analogs: Production of Altered DNA and Peptide Sequences by Random Methods Amino acid sequence variants of a protein can be prepared by random mutagenesis of DNA which encodes a protein or a particular domain or region of a protein. Useful methods include PCR mutagenesis and saturation mutagenesis. A library of random amino acid sequence variants can also be generated by the synthesis of a set of degenerate oligonucleotide sequences. (Methods for screening proteins in a library of variants are elsewhere herein.) 35 PCR Mutagenesis In PCR mutagenesis, reduced Taq polymerase fidelity is used to introduce random mutations into a cloned fragment of DNA (Leung et al., 1989, Technique 1 :11-15). This is a very powerful and relatively rapid method of introducing random mutations. The DNA region to be mutagenized is amplified using the polymerase chain reaction (PCR) under conditions that reduce the fidelity of DNA synthesis by Taq DNA polymerase, e.g., by using a dGTP/dATP ratio of five and adding Mn 2+ to the PCR reaction. The pool of amplified DNA fragments are inserted into appropriate cloning vectors to provide random mutant libraries. Saturation Mutagenesis Saturation mutagenesis allows for the rapid introduction of a large number of single base substitutions into cloned DNA fragments (Mayers et al., 1985, Science 229:242). This technique includes generation of mutations, e.g., by chemical treatment or irradiation of single-stranded DNA in vitro, and synthesis of a complimentary DNA strand. The mutation frequency can be modulated by modulating the severity of the treatment, and essentially all possible base substitutions can be obtained. Because this procedure does not involve a genetic selection for mutant fragments both neutral substitutions, as well as those that alter function, are obtained. The distribution of point mutations is not biased toward conserved sequence elements. Degenerate Oligonucleotides A library of homologs can also be generated from a set of degenerate oligonucleotide sequences. Chemical synthesis of a degenerate sequences can be carried out in an automatic DNA synthesizer, and the synthetic genes then ligated into an appropriate expression vector. The synthesis of degenerate oligonucleotides is known in the art (see for example, Narang, SA (1983) Tetrahedron 39:3; Itakura et al. (1981) Recombinant DNA, Proc 3rd Cleveland Sympos. Macromolecules, ed. AG Walton, Amsterdam: Elsevier pp273-289; Itakura et al. (1984) Annu. Rev. Biochem. 53:323; Itakura et al. (1984) Science 198:1056; Ike et al. (1983) Nucleic Acid Res. 11:477. Such techniques have been employed in the directed evolution of other proteins (see, for example, Scott et al. (1990) Science 249:386-390; Roberts et al. (1992) PNAS 89:2429- 2433; Devlin et al. (1990) Science 249: 404-406; Cwirla et al. (1990) PNAS 87: 6378-6382; as well as U.S. Patents Nos. 5,223,409, 5,198,346, and 5,096,815). Generation of Analogs: Production of Altered DNA and Peptide Sequences bv Directed Mutagenesis 36 Non-random or directed, mutagenesis techniques can be used to provide specific sequences or mutations in specific regions. These techniques can be used*to create variants which include, e.g., deletions, insertions, or substitutions, of residues of the known amino acid sequence of a protein. The sites for mutation can be modified individually or in series, e.g., by (1) substituting first with conserved amino acids and then with more radical choices depending upon results achieved, (2) deleting the target residue, or (3) inserting residues of the same or a different class adjacent to the located site, or combinations of options 1-3. Alanine Scanning Mutagenesis Alanine scanning mutagenesis is a useful method for identification of certain residues or regions of the desired protein that are preferred locations or domains for mutagenesis, Cunningham and Wells (Science 244:1081-1085, 1989). In alanine scanning, a residue or group of target residues are identified (e.g., charged residues such as Arg, Asp, His, Lys, and Glu) and replaced by a neutral or negatively charged amino acid (most preferably alanine or polyalanine). Replacement of an amino acid can affect the interaction of the amino acids with the surrounding aqueous environment in or outside the cell. Those domains demonstrating functional sensitivity to the substitutions are then refined by introducing further or other variants at or for the sites of substitution. Thus, while the site for introducing an amino acid sequence variation is predetermined, the nature of the mutation per se need not be predetermined. For example, to optimize the performance of a mutation at a given site, alanine scanning or random mutagenesis may be conducted at the target codon or region and the expressed desired protein subunit variants are screened for the optimal combination of desired activity. Oligonucleotide-Mediated Mutagenesis Oligonucleotide-mediated mutagenesis is a useful method for preparing substitution, deletion, and insertion variants of DNA, see, e.g., Adelman et al., (DNA 2:183, 1983). Briefly, the desired DNA is altered by hybridizing an oligonucleotide encoding a mutation to a DNA template, where the template is the single-stranded form of a plasmid or bacteriophage containing the unaltered or native DNA sequence of the desired protein. After hybridization, a DNA polymerase is used to synthesize an entire second complementary strand of the template that will thus incorporate the oligonucleotide primer, and will code for the selected alteration in the desired protein DNA. Generally, oligonucleotides of at least 25 nucleotides in length are used. An optimal oligonucleotide will have 12 to 15 nucleotides that are completely complementary to the template on either side of the nucleotide(s) coding for the mutation. This ensures that the oligonucleotide will 37 hybridize properly to the single-stranded DNA template molecule. The oligonucleotides are readily synthesized using techniques known in the art such as that described by Crea et al. (Proc. Natl. Acad. Sci. USA, 75: 5765[1978]). Cassette Mutagenesis Another method for preparing variants, cassette mutagenesis, is based on the technique described by Wells et al. (Gene, 34:315[1985]). The starting material is a plasmid (or other vector) which includes the protein subunit DNA to be mutated. The codon(s) in the protein subunit DNA to be mutated are identified. There must be a unique restriction endonuclease site on each side of the identified mutation site(s). If no such restriction sites exist, they may be generated using the above-described oligonucleotide- mediated mutagenesis method to introduce them at appropriate locations in the desired protein subunit DNA. After the restriction sites have been introduced into the plasmid, the plasmid is cut at these sites to linearize it. A double-stranded oligonucleotide encoding the sequence of the DNA between the restriction sites but containing the desired mutation(s) is synthesized using standard procedures. The two strands are synthesized separately and then hybridized together using standard techniques. This double-stranded oligonucleotide is referred to as the cassette. This cassette is designed to have 3' and 5' ends that are comparable with the ends of the linearized plasmid, such that it can be directly ligated to the plasmid. This plasmid now contains the mutated desired protein subunit DNA sequence. Combinatorial Mutagenesis Combinatorial mutagenesis can also be used to generate mutants. E.g., the amino acid sequences for a group of homologs or other related proteins are aligned, preferably to promote the highest homology possible. All of the amino acids which appear at a given position of the aligned sequences can be selected to create a degenerate set of combinatorial sequences. The variegated library of variants is generated by combinatorial mutagenesis at the nucleic acid level, and is encoded by a variegated gene library. For example, a mixture of synthetic oligonucleotides can be enzymatically ligated into gene sequences such that the degenerate set of potential sequences are expressible as individual peptides, or alternatively, as a set of larger fusion proteins containing the set of degenerate sequences. Primary High-Through-Put Methods for Screening Libraries of Peptide Fragments or Homologs 38 Various techniques are known in the art for screening generated mutant gene products. Techniques for screening large gene libraries often include cloning the gene library into replicable expression vectors, transforming appropriate cells with the resulting library of vectors, and expressing the genes under conditions in which detection of a desired activity, e.g., in this case, binding to other sciellin subunits, assembly into a trimeric sciellin molecules, binding to natural ligands or substrates, facilitates relatively easy isolation of the vector encoding the gene whose product was detected. Each of the techniques described below is amenable to high through-put analysis for screening large numbers of sequences created, e.g., by random mutagenesis techniques. Two Hybrid Systems Two hybrid (interaction trap) assays such as the system described above (as with the other screening methods described herein), can be used to identify fragments or analogs (see e.g., U.S. Patent No.: 5,283,317; PCT publication WO94/10300; Zervos et al. (1993) Cell 72:223-232; Madura et al. (1993) J Biol Chem 268:12046-12054; Bartel et al. (1993) Biotechniques 14:920-924; and Iwabuchi et al. (1993) Oncogene 8:1693-1696). These may include agonists, superagonists, and antagonists. (The subject protein and a protein it interacts with are used as the bait protein and fish proteins.). These assays rely on detecting the reconstitution of a functional transcriptional activator mediated by protein- protein interactions with a bait protein. In particular, these assays make use of chimeric genes which express hybrid proteins. The first hybrid comprises a DNA-binding domain fused to the bait protein, e.g., a sciellin molecule or a fragment thereof, e.g., the LIM domain. The second hybrid protein contains a transcriptional activation domain fused to a "fish" protein, e.g. an expression library, e.g., a keratinocyte expression library. If the fish and bait proteins are able to interact, they bring into close proximity the DNA-binding and transcriptional activator domains. This proximity is sufficient to cause transcription of a reporter gene which is operably linked to a transcriptional regulatory site which is recognized by the DNA binding domain, and expression of the marker gene can be detected and used to score for the interaction of the bait protein with another protein. Display Libraries In one approach to screening assays, the candidate peptides are displayed on the surface of a cell or viral particle, and the ability of particular cells or viral particles to bind an appropriate receptor protein via the displayed product is detected in a "panning assay". For example, the gene library can be cloned into the gene for a surface membrane protein of a bacterial cell, and the resulting fusion protein detected by panning (Ladner et al., WO 88/06630; Fuchs et al. (1991) Bio/Technology 9:1370-1371; and Goward et al. (1992) TIBS 39 18: 136-140). In a similar fashion, a detectably labeled ligand can be used to score for potentially functional peptide homologs. Fluorescently labeled ligands, e.g., receptors, can be used to detect homo log which retain ligand-binding activity. The use of fluorescently labeled ligands, allows cells to be visually inspected and separated under a fluorescence microscope, or, where the morphology of the cell permits, to be separated by a fluorescence-activated cell sorter. A gene library can be expressed as a fusion protein on the surface of a viral particle. For instance, in the filamentous phage system, foreign peptide sequences can be expressed on the surface of infectious phage, thereby conferring two significant benefits. First, since these phage can be applied to affinity matrices at concentrations well over 10 13 phage per milliliter, a large number of phage can be screened at one time. Second, since each infectious phage displays a gene product on its surface, if a particular phage is recovered from an affinity matrix in low yield, the phage can be amplified by another round of infection. The group of almost identical E. coli filamentous phages Ml 3, fd., and fl are most often used in phage display libraries. Either of the phage gill or gVIII coat proteins can be used to generate fusion proteins without disrupting the ultimate packaging of the viral particle. Foreign epitopes can be expressed at the NH2-terminal end of pill and phage bearing such epitopes recovered from a large excess of phage lacking this epitope (Ladner et al. PCT publication WO 90/02909; Garrard et al., PCT publication WO 92/09690; Marks et al. (1992) J. Biol. Chem. 267:16007-16010; Griffiths et al. (1993) EMBO J 12:725-734; Clackson et al. (1991) Nature 352:624-628; and Barbas et al. (1992) PNAS 89:4457-4461). A common approach uses the maltose receptor of E. coli (the outer membrane protein, LamB) as a peptide fusion partner (Charbit et al. (1986) EMBO 5, 3029-3037). Oligonucleotides have been inserted into plasmids encoding the LamB gene to produce peptides fused into one of the extracellular loops of the protein. These peptides are available for binding to ligands, e.g., to antibodies, and can elicit an immune response when the cells are administered to animals. Other cell surface proteins, e.g., OmpA (Schorr et al. (1991) Vaccines 91, pp. 387-392), PhoE (Agterberg, et al. (1990) Gene 88, 37-45), and PAL (Fuchs et al. (1991) Bio/Tech 9, 1369-1372), as well as large bacterial surface structures have served as vehicles for peptide display. Peptides can be fused to pilin, a protein which polymerizes to form the pilus-a conduit for interbacterial exchange of genetic information (Thiry et al. (1989) Appl. Environ. Microbiol. 55, 984-993). Because of its role in interacting with other cells, the pilus provides a useful support for the presentation of peptides to the extracellular environment. Another large surface structure used for peptide display is the bacterial motive organ, the flagellum. Fusion of peptides to the subunit protein flagellin offers a dense array of may peptides copies on the host cells (Kuwajima et al. (1988) Bio/Tech. 6, 1080-1083). Surface proteins of other bacterial 40 species have also served as peptide fusion partners. Examples include the Staphylococcus protein A and the outer membrane protease IgA oϊNeisseria (Hansson et al. (1992) J. Bacteriol. 174, 4239-4245 and Klauser et al. (1990) EMBO J. 9, 1991-1999). In the filamentous phage systems and the LamB system described above, the physical link between the peptide and its encoding DNA occurs by the containment of the DNA within a particle (cell or phage) that carries the peptide on its surface. Capturing the peptide captures the particle and the DNA within. An alternative scheme uses the DNA- binding protein Lad to form a link between peptide and DNA (Cull et al. (1992) PNAS USA 89:1865-1869). This system uses a plasmid containing the Lad gene with an oligonucleotide cloning site at its 3'-end. Under the controlled induction by arabinose, a Lacl-peptide fusion protein is produced. This fusion retains the natural ability of Lad to bind to a short DNA sequence known as LacO operator (LacO). By installing two copies of LacO on the expression plasmid, the Lacl-peptide fusion binds tightly to the plasmid that encoded it. Because the plasmids in each cell contain only a single oligonucleotide sequence and each cell expresses only a single peptide sequence, the peptides become specifically and stably associated with the DNA sequence that directed its synthesis. The cells of the library are gently lysed and the peptide-DNA complexes are exposed to a matrix of immobilized receptor to recover the complexes containing active peptides. The associated plasmid DNA is then reintroduced into cells for amplification and DNA sequencing to determine the identity of the peptide ligands. As a demonstration of the practical utility of the method, a large random library of dodecapeptides was made and selected on a monoclonal antibody raised against the opioid peptide dynorphin B. A cohort of peptides was recovered, all related by a consensus sequence corresponding to a six- residue portion of dynorphin B. (Cull et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89-1869) This scheme, sometimes referred to as peptides-on-plasmids, differs in two important ways from the phage display methods. First, the peptides are attached to the C- terminus of the fusion protein, resulting in the display of the library members as peptides having free carboxy termini. Both of the filamentous phage coat proteins, pill and pVIII, are anchored to the phage through their C-termini, and the guest peptides are placed into the outward-extending N-terminal domains. In some designs, the phage-displayed peptides are presented right at the amino terminus of the fusion protein. (Cwirla, et al. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 6378-6382) A second difference is the set of biological biases affecting the population of peptides actually present in the libraries. The Lad fusion molecules are confined to the cytoplasm of the host cells. The phage coat fusions are exposed briefly to the cytoplasm during translation but are rapidly secreted through the inner membrane into the periplasmic compartment, remaining anchored in the membrane by their C-terminal hydrophobic domains, with the N-termini, containing the peptides, 41 protruding into the periplasm while awaiting assembly into phage particles. The peptides in the Lad and phage libraries may differ significantly as a result of their exposure to different proteolytic activities. The phage coat proteins require transport across the inner membrane and signal peptidase processing as a prelude to incorporation into phage. Certain peptides exert a deleterious effect on these processes and are underrepresented in the libraries (Gallop et al. (1994) J. Med. Chem. 37(9):1233-1251). These particular biases are not a factor in the Lad display system. The number of small peptides available in recombinant random libraries is enormous. Libraries of 10 7 -10 9 independent clones are routinely prepared. Libraries as large as 10 1 1 recombinants have been created, but this size approaches the practical limit for clone libraries. This limitation in library size occurs at the step of transforming the DNA containing randomized segments into the host bacterial cells. To circumvent this limitation, an in vitro system based on the display of nascent peptides in polysome complexes has recently been developed. This display library method has the potential of producing libraries 3-6 orders of magnitude larger than the currently available phage/phagemid or plasmid libraries. Furthermore, the construction of the libraries, expression of the peptides, and screening, is done in an entirely cell-free format. In one application of this method (Gallop et al. (1994) J. Med. Chem. 37(9): 1233- 1251), a molecular DNA library encoding 10 12 decapeptides was constructed and the library expressed in an E. coli S30 in vitro coupled transcription/translation system. Conditions were chosen to stall the ribosomes on the mRNA, causing the accumulation of a substantial proportion of the RNA in polysomes and yielding complexes containing nascent peptides still linked to their encoding RNA. The polysomes are sufficiently robust to be affinity purified on immobilized receptors in much the same way as the more conventional recombinant peptide display libraries are screened. RNA from the bound complexes is recovered, converted to cDNA, and amplified by PCR to produce a template for the next round of synthesis and screening. The polysome display method can be coupled to the phage display system. Following several rounds of screening, cDNA from the enriched pool of polysomes was cloned into a phagemid vector. This vector serves as both a peptide expression vector, displaying peptides fused to the coat proteins, and as a DNA sequencing vector for peptide identification. By expressing the polysome-derived peptides on phage, one can either continue the affinity selection procedure in this format or assay the peptides on individual clones for binding activity in a phage ELIS A, or for binding specificity in a completion phage ELIS A (Barret, et al. (1992) Anal. Biochem 204,357-364). To identify the sequences of the active peptides one sequences the DNA produced by the phagemid host. 42 Secondary Screens The high through-put assays described above can be followed by secondary screens in order to identify further biological activities which will, e.g., allow one skilled in the art to differentiate agonists from antagonists. The type of a secondary screen used will depend on the desired activity that needs to be tested. For example, an assay can be developed in which the ability to inhibit an interaction between a protein of interest and its respective ligand can be used to identify antagonists from a group of peptide fragments isolated though one of the primary screens described above. Therefore, methods for generating fragments and analogs and testing them for activity are known in the art. Once the core sequence of interest is identified, it is routine to perform for one skilled in the art to obtain analogs and fragments. Peptide Mimetics The invention also provides for reduction of the protein binding domains of the subject sciellin polypeptides to generate mimetics, e.g. peptide or non-peptide agents. See, for example, "Peptide inhibitors of human papillomavirus protein binding to retinoblastoma gene protein" European patent applications EP-412,762A and EP- B31.080A. Non-hydrolyzable peptide analogs of critical residues can be generated using benzodiazepine (e.g., see Freidinger et al. in Peptides: Chemistry and Biology, G.R. Marshall ed., ESCOM Publisher: Leiden, Netherlands, 1988), azepine (e.g., see Huffman et al. in Peptides: Chemistry and Biology, G.R. Marshall ed., ESCOM Publisher: Leiden, Netherlands, 1988), substituted gama lactam rings (Garvey et al. in Peptides: Chemistry and Biology, G.R. Marshall ed., ESCOM Publisher: Leiden, Netherlands, 1988), keto- methylene pseudopeptides (Ewenson et al. (1986) J Med Chem 29:295; and Ewenson et al. in Peptides: Structure and Function (Proceedings of the 9th American Peptide Symposium) Pierce Chemical Co. Rockland, IL, 1985), β-turn dipeptide cores (Nagai et al. (1985) Tetrahedron Lett 26:647; and Sato et al. (\9S6) J Chem Soc Perkin Trans 1 :1231), and β-aminoalcohols (Gordon et al. (1985) Biochem Biophys Res Commun\26:4\9; and Dann et al. (1986) Biochem Biophys Res Commun 134:71). Antibodies The invention also includes antibodies specifically reactive with a subject sciellin polypeptides. Anti-protein/anti-peptide antisera or monoclonal antibodies can be made as described herein by using standard protocols (See, for example, Antibodies: A Laboratory Manual ed. by Harlow and Lane (Cold Spring Harbor Press: 1988)). 43 Antibodies which specifically bind sciellin epitopes can also be used in immunohistochemical staining of tissue samples in order to evaluate the abundance and pattern of expression of sciellin. Anti-sciellin antibodies can be used diagnostically in immuno-precipitation and immuno-blotting to detect and evaluate sciellin levels in tissue or bodily fluid as part of a clinical testing procedure. Another application of antibodies of the present invention is in the immunological screening of cDNA libraries constructed in expression vectors such as λgtl l, λgt 18-23, λZAP, and λORF8. Messenger libraries of this type, having coding sequences inserted in the correct reading frame and orientation, can produce fusion proteins. For instance, λgtl 1 will produce fusion proteins whose amino termini consist of β-galactosidase amino acid sequences and whose carboxy termim consist of a foreign polypeptide. Antigenic epitopes of a subject polypeptide can then be detected with antibodies, as, for example, reacting nitrocellulose filters lifted from infected plates with antibodies of the invention. Phage, scored by this assay, can then be isolated from the infected plate. Thus, the presence of homologs can be detected and cloned from other animals, and alternate isoforms (including splicing variants) can be detected and cloned from human sources. Other Embodiments Included in the invention are: allelic variations; natural mutants; induced mutants; proteins encoded by DNA that hybridizes under high or low stringency conditions to a nucleic acid which encodes a polypeptide of SEQ ID NO:2 (for definitions of high and low stringency see Current Protocols in Molecular Biology, John Wiley & Sons, New York, 1989, 6.3.1 - 6.3.6, hereby incorporated by reference); and, polypeptides specifically bound by antisera to sciellin. Nucleic acids and polypeptides of the invention includes those that differ from the sequences disco losed herein by virtue of sequencing errors in the disclosed sequences. The invention also includes fragments, preferably biologically active fragments, or analogs of sciellin. A biologically active fragment or analog is one having any in vivo or in vitro activity which is characteristic of sciellin shown in SEQ ID NO:2, or of other naturally occurring sciellin, e.g., one or more of the biological activities described above. Especially preferred are fragments which exist in vivo, e.g., fragments which arise from post transcriptional processing or which arise from translation of alternatively spliced RNA's. Fragments include those expressed in native or endogenous cells, e.g., as a result of post-translational processing, e.g., as the result of the removal of an amino-terminal signal sequence, as well as those made in expression systems, e.g., in CHO cells. 44 Particularly preferred fragments are fragments, e.g., active fragments, which are generated by proteolytic cleavage or alternative splicing events. 45

Claims: CLAIMS 1. A substantially pure nucleic acid comprising a nucleotide sequence which is at least 60% identical to the nucleotide sequence of SEQ ID NO:l. 2. The nucleic acid of claim 1 comprising the nucleotide sequence of SEQ LD NO:l. 3. The nucleic acid of claim 1, wherein the nucleic acid hybridizes under high stringency conditions to a nucleic acid which encodes a Sceillin polypeptide, or a complement thereof. 4. The nucleic acid of claim 1, wherein the nucleic acid encodes a polypeptide that reacts with an antibody specific for a Sciellin polypeptide. 5. A substantially pure nucleic acid which encodes a fragment of a Sciellin polypeptide of at least 50 amino acids in length. 6. A substantially pure polypeptide which comprises at least 60% sequence identity to a Sciellin polypeptide. 7. The Sciellin polypeptide of claim 6 comprising the amino acid sequence of SEQ ID NO:2. 8. An substantially pure Sciellin polypeptide which is encoded by a nucleic acid having at least 85% sequence identity with the nucleic acid of SEQ ID NO: 1. 9. The pure polypeptide of claim 6, wherein the Sciellin polypeptide has any one or all of the following properties: (i) it has the ability to form homotrimeric beta helices; 46 (ii) it acts as a precursor of the cornified envelope of keratinizing tissues; (iii) it provides structural support to the cornified envelopes of stratum corneum cells; (iv) it promotes adhesion between tissue elements; (v) it promotes intracellular signalling; (vi) it defines cell shape; (vii) it can act as an adaptor element to promote the assembly and targeting of multiprotein complexes; (viii) it has a molecular weight, amino acid composition or other physical characteristic of sciellin of SEQ ID NO:2; (ix) it has an overall sequence similarity of at least 50%, preferably at least 60%, more preferably at least 70, 80, 90, or 95%, with a sciellin polypeptide of SEQ LD NO:2; (x) it is found in human placenta; (xi) it has a central domain composed of repeats which is preferably about 70%, 80%, 90% or 95% identical to amino acid residues 231 -543 of SEQ ID NO:2; (xii) it has a carboxyl domain containing a single LIM domain which is preferably about 70%, 80%, 90% or 95% identical to amino acid residues 600-662 of SEQ ID NO:2; (xiii) it has a pi of about 10; (xiv) it can be expressed in the stratum granulosum of human foreskin tissue; and (xv) it can expressed in the peripheral cytoplasm in hair follicles, upper cell layer of epidermis, as well as the epithelium of the oral cavity, esophagus, vagina, ureter and cornea. 10. A fragment of the Sciellin polypeptide of claim 8 which is at least 50 amino acids in length. 11. A substantially pure Sciellin polypeptide comprising a central domain containing sixteen repeats and a C-terminal LIM domain.. 12. A vector comprising the nucleic acid of any of claims 1-5. 47 13. A cell comprising the nucleic acid of any of claims 1-5 and 12. . 14. A purified preparation of an anti-Sciellin antibody. 15. A method for manufacture of a Sciellin peptide comprising culturing the cell of claim 11 in a medium to express the Sciellin polypeptide. 16. An immunogen comprising a Sciellin polypeptide in an immunogenic preparation, the immunogen being capable of eliciting an immune response specific for the Sciellin polypeptide. 17. A transgenic Sciellin animal. 18. A method of inducing differentiation of keratinocytes, the method comprises contacting a keratinocyte with a sufficient amount of a Sciellin molecule to induce differentiation. 19. A method of promoting hair growth, comprising contacting a hair stem cells with an amount of a Sciellin molecule sufficient to induce hair growth. 20. A method of promoting adhesion of a first tissue element to a second tissue element comprising contacting one or both of the first tissue element and the second tissue element with a sufficient amount of a Sciellin molecule to promote adhesion. 21. A method of promoting wound healing in a subj ect comprising administering an amount of a Sciellin molecule sufficient to promote healing to the wound 22. A method of treating or preventing in a subject a Sciellin- related disorder, the method comprising administering to the subject an effective amount of sciellin molecule effective to treat or prevent the sciellin- related disorder in the subject. 23. A method of determining if a subject is at risk for a disorder related to a lesion in or the misexpression of a gene which encodes a Sciellin polypeptide comprising detecting, in a tissue of the subject, the presence or absence of a mutation which affects the expression of the Sciellin gene. 48 24. A method of evaluating a compound for the ability to interact with a subject Sciellin polypeptide comprising contacting the compound with the subject Sciellin polypeptide; and evaluating ability of the compound to interact with the subject Sciellin polypeptide. 25. A method of evaluating a compound for the ability to bind a nucleic acid encoding a subject Sciellin polypeptide, the method comprises contacting the compound with the nucleic acid and evaluating ability of the compound to form a complex with the nucleic acid. 49

Inventors: BADEN HOWARD P, CHAMPLIAUD MARIE-FRANCE, OLSON PAMELA, BADEN, HOWARD, P., CHAMPLIAUD, MARIE-FRANCE, OLSON, PAMELA
Applicants: GEN HOSPITAL CORP, THE GENERAL HOSPITAL CORPORATION
Application year: 1999
Main classification: A61K38
IPC codes: A01K67, A61K38, A61K39, A61P17, A61P43, C07K14, C07K16, C12N1, C12N5, C12N15, C12P21, G01N33