Integrin alpha v subunit is expressed on mesodermal cell surfaces during amphibian gastrulation.

Mesodermal cell migration during amphibian gastrulation is dependent on cellular interactions with fibronectin. One mechanism whereby cells bind fibronectin is through alpha v-containing integrin heterodimers. In order to investigate the role of alpha v in amphibian gastrulation, we have cloned the Pleurodeles homologue of the integrin alpha v subunit using homology PCR. The deduced amino acid sequence is 73 and 74% identical with the human and chick homologues, respectively. The 4.8-kb mRNA is expressed during oogenesis and persists throughout development. Messenger RNA and protein are widely expressed in oocytes and embryos while cell surface expression is spatially regulated. The protein first appears on the plasma membrane of fully grown oocytes. Fertilization results in the progressive loss of alpha v membrane localization. Before and during gastrulation, the integrin alpha v subunit is expressed on the surface of mesodermal cells. These data show that alpha v expression is developmentally regulated by a post-translational mechanism which correlates with the onset of mesodermal cell migration at gastrulation.