Regulation of endothelial cell adherens junctions by a Ras-dependent signal transduction pathway

Adherens junctions, consisting of transmembrane cadherin molecules and thei r associated cytoplasmic alpha-, beta-, and gamma-catenin proteins, are tho ught to be critical for the development of stable cell adhesion and subsequ ent 3-dimensional tissue organization. In human endothelial cells there is a marked induction of gamma-catenin levels when cells reach confluence. We demonstrate that expression of a dominant negative ras gene product (N17ras ) via adenoviral mediated gene transfer inhibits the confluent-dependent ri se in gamma-catenin mRNA and protein levels. Consistent with its effects on overall gamma-catenin levels, expression of N17ras also reduces the amount of gamma-catenin associated with the adherens junction. Finally, although expression of N17ras under normal culture conditions produces no clear morp hological phenotype, endothelial cells expressing a dominant negative ras g ene product fail to form 3-dimensional, vascular-like structures when plate d on reconstituted extracellular matrix, (C) 1999 Academic Press.