title: Identification and characterization of a novel squamous cell-associated gene related to PMP22.
abstract: In this study, we identify and characterize a novel gene, CL-20, that encodes a 17.8-kDa protein with sequence and structural similarity to the growth arrest-specific gene gas3/peripheral myelin protein gene PMP22. The CL-20 protein exhibits a 43% identity with PMP22. The positions of the four lipophilic domains and the N-glycosylation site of PMP22 are conserved in CL-20, suggesting that it also is an integral membrane glycoprotein. The CL-20 gene is located on human chromosome 12 rather than 17 and encodes a 2.8-kilobase mRNA instead of 1.7-kilobase mRNA. These observations indicate that the CL-20 gene is related to but distinct from PMP22. In contrast to PMP22, CL-20 mRNA and protein are induced during squamous differentiation of rabbit tracheal epithelial cells in vitro, and Northern blot analysis and in situ hybridization demonstrated that CL-20 mRNA is most abundant in squamous epithelia. These results indicate that the high expression of CL-20 is closely correlated with squamous differentiation. The differences in tissue-specific expression and regulation between CL-20 and PMP22 suggest different roles for these two proteins. Retinoids, which inhibit squamous differentiation, repress the induction of CL-20. The retinoic acid receptor-selective retinoid SRI-6751-84 is the most effective in suppressing CL-20, suggesting that the activation of the retinoic acid receptor signaling pathway is important in this suppression.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D002460:Cell Line; D002874:Chromosome Mapping; D002881:Chromosomes, Human, Pair 12; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004847:Epithelial Cells; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D009185:Myelin Proteins / Q000737:chemistry / Q000235:genetics*; D009363:Neoplasm Proteins; D011817:Rabbits; D011956:Receptors, Cell Surface; D012176:Retinoids / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D009185:Myelin Proteins; D009363:Neoplasm Proteins; C073687:PMP22 protein, human; D011956:Receptors, Cell Surface; D012176:Retinoids; C097051:epithelial membrane protein-1