Differential regulation of phosphoinositide metabolism by αVβ3 and αVβ5 integrins upon smooth muscle cell migration

Abstract

Smooth muscle cell migration is a key step of atherosclerosis and angiogenesis. We demonstrate that αVβ3 and αVβ5 integrins synergistically regulate smooth muscle cell migration onto vitronectin. Using an original haptotactic cell migration assay, we measured a strong stimulation of phosphoinositide metabolism in migrating vascular smooth muscle cells. Phosphatidic acid production and phosphoinositide 3-kinase IA activation were triggered only upon αVβ3 engagement. Blockade of αVβ3 engagement or phospholipase C activity resulted in a strong inhibition of smooth muscle cell spreading on vitronectin. By contrast, blockade of αVβ5 reinforced elongation and polarization of cell shape. Moreover, Pyk2-associated tyrosine kinase and phosphoinositide 4-kinase activities measured in Pyk2 immunoprecipitates were stimulated upon cell migration. Blockade of either αVβ3 or αVβ5 function, as well as inhibition of phospholipase C activity, decreased both Pyk2-associatcd activities. We demonstrated that the Pyk2-associated phosphoinositide 4-kinase corresponded to the β isoform. Our data point to the metabolism of phosphoinositides as a regulatory pathway for the differential roles played by αVβ3 and αVβ3 upon cell migration and identify the Pyk2-associated phosphoinositide 4-kinase β as a common target for both integrins. © 2001 by The American Society for Biochemistry and Molecular Biology, Inc.