Identification of a conserved cluster of skin-specific genes encoding secreted proteins.
Terminal differentiation of keratinocytes results in the formation of a cornified layer composed of cross-linked intracellular and extracellular material. Using a signal trap expression screening strategy, we have identified four cDNAs encoding secreted proteins potentially involved in this process. One of the cDNAs is identical to the short isoform of suprabasin, a recently described epidermis-specific protein, which is shown here to contain a functional secretory signal. The second cDNA, sk89, encodes a protein of 493 amino acids, rich in glycine and serine residues. The third cDNA encodes a C-terminal fragment of SK89 (amino acids 410-493). It comprises exons 13 to 18 of the sk89 locus but transcription starts at an isoform-specific exon encoding a distinct secretory signal. The fourth cDNA encodes keratinocyte differentiation-associated protein (KDAP), a precursor protein of 102 amino acids. Subcellular localization by immunofluorescence and detection of the tagged proteins by Western blotting confirmed that the four proteins are secreted. Northern analysis and in situ hybridization revealed that expression of the corresponding genes was restricted to the suprabasal keratinocytes of the epidermis. These genes encoding epidermis-specific secreted products are found in a conserved cluster on human chromosome 19q13.12 and on mouse chromosome 7A3.
Moffatt
Pierre
P
Phenogene Therapeutics Inc., 416 de Maisonneuve West, Suite 1020, Montreal, Quebec, Canada H3A 1L2. moffattp@phenogene.com
Salois
Patrick
P
St-Amant
Natalie
N
Gaumond
Marie-Hélène
MH
Lanctôt
Christian
C
D000595:Amino Acid Sequence; D000818:Animals; D000943:Antigens, Differentiation / Q000235:genetics* / Q000378:metabolism; D016282:Aspartic Acid Endopeptidases / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D002874:Chromosome Mapping / Q000379:methods; D002888:Chromosomes, Human, Pair 19 / Q000235:genetics; D033481:Chromosomes, Mammalian / Q000235:genetics; D003001:Cloning, Molecular; D017124:Conserved Sequence / Q000235:genetics; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D005091:Exons; D020869:Gene Expression Profiling; D023061:Gene Order; D005796:Genes / Q000235:genetics; D049452:Green Fluorescent Proteins; D006801:Humans; D007438:Introns; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D012867:Skin / Q000378:metabolism*; D014162:Transfection
D000943:Antigens, Differentiation; D018076:DNA, Complementary; D008164:Luminescent Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; C491424:Sk89 protein, mouse; C470006:suprabasin protein, mouse; D049452:Green Fluorescent Proteins; D016282:Aspartic Acid Endopeptidases; C104073:Kdap protein, mouse