Expression of Embryo-Specific Epidermal XK81 Keratin Gene in Dissociated Cells of Xenopus laevis Animal Caps Co-cultured with Mesoderm-Inducing Vegetal Cells. (Xenopus embryonic cells/dissociated animal cap/keratin gene expression/alpha-actin mRNA/mesodermal induction)

Molecular cloning of cDNA for XTCAD-1, a novel Xenopus cadherin, and its expression in adult tissues and embryos of Xenopus laevis

We have isolated from a Xenopus tailbud cDNA library a novel cadherin cDNA, denoted as XTCAD-1, which contained an open reading frame including the entire coding region. XTCAD-1 codes for 714 amino acids (molecular mass: 96 kDa), which include five characteristic extracellular cadherin motifs, a single putative transmembrane domain, and a cytoplasmic domain. In each domain, XTCAD-1 shared extensive homologies with other cadherins, and was related to EP-, E-, and P-cadherins more closely than to N- and M-cadherins. In adult Xenopus, XTCAD-1 mRNA was strongly expressed in intestine/stomach, kidney and skin, which are respectively derived from endoderm, mesoderm, and ectoderm. In Xenopus embryogenesis, expression of XTCAD-1 mRNA was first detected at blastula stage, and the level of the expression increased gradually during gastrula stage, reached a peak at tailbud stage and then decreased slightly at tadpole stage. These results suggest that in Xenopus laevis XTCAD-1 plays an important role in the maintenance of adult tissues that contain epithelial cells abundantly and also in morphogenesis in early embryonic development.