Kdap, a novel gene associated with the stratification of the epithelium

The skin develops and differentiates during embryogenesis, which is concert edly regulated by a variety of genes. The present study isolated from the r at embryonic skin a novel differentiation-associated gene named Kdap, (kera tinocyte differentiation-associated protein) by suppression subtractive hyb ridization between the skin of 14 day postcoitus (dpc) embryo (the prehair- germ stage) and that of 17 dpc embryo (the hair-germ stage). Its mRNA conta ined four spliced forms in these tissues. The gene encoded a protein of tot al 98 amino acids with a calculated molecular mass of 11 kDa and an isoelec tric point of 6.1 as an unspliced form. The two splicing zones were well co nserved among rat, mouse, and human. This protein had a high hydrophobic N- terminal region, a possible signal sequence, and contained two putative N-m yristoylation sites and two casein kinase II phosphorylation sites. In situ hybridization experiments detected Kdap transcripts exclusively in the sup rabasal cell layers of the embryonic epidermis. Intense expression was also seen in suprabasal cells in regions of infundibulum of the hair follicle. These results indicated that Kdap provides a new insight into the mechanism of differentiation and the maintenance of stratified epithelia. (C) 2000 E lsevier Science B.V. All rights reserved.