MOLECULAR ANALYSIS AND DEVELOPMENTAL EXPRESSION OF THE FOCAL ADHESIONKINASE PP125(FAK) IN XENOPUS-LAEVIS

Integrin-mediated cellular adhesion to components of the extracellular matrix (ECM) is important in a number of morphogenetic events that oc cur during vertebrate embryogenesis. Recent studies suggest that the f ocal adhesion kinase pp125(FAK) is involved in the regulation of integ rin-dependent signaling processes triggered by cell adhesion to the EC M. We report the cDNA cloning and sequence analysis of the Xenopus hom olog of pp125(FAK). We also describe temporal and spatial patterns of FAK expression during early development. Xenopus FAK shares greater th an 90% identity with its avian and mammalian homologs. FAK mRNA and pr otein are present in the fertilized egg and in cleavage stage embryos. During gastrulation, FAK protein expression increases significantly a nd is detected in mesoderm, marginal zone ectoderm, and cells of the b lastocoel roof. Later in development, FAK is prominently expressed at intersomitic junctions, in the brain, and in several cranial nerves. P hosphotyrosyl-FAK is first detected during gastrulation, suggesting th at the phosphorylation of FAK on tyrosine is developmentally regulated . These data indicate that FAK is likely to participate in a variety o f integrin-ECM-dependent signaling events during morphogenesis. (C) 19 95 Academic Press, Inc.