βig-h3 triggers signaling pathways mediating adhesion and migration of vascular smooth muscle cells through αvβ5 integrin

Abstract

Adhesion and migration of vascular smooth muscle cells (VSMCs) play an important role in the pathogenesis of atherosclerosis. These processes involve the interaction of VSMCs with extracellular matrix proteins. Here, we investigated integrin isoforms and signaling pathways mediating the adhesion and migration of VSMCs on βig-h3, a transforming growth factor (TGF)-β-inducible extracellular matrix protein that is elevated in atherosclerotic plaques. Adhesion assays showed that the αvβ5 integrin is a functional receptor for the adhesion of aortic VSMCs to βig-h3. An YH18 motif containing amino acids between 563 and 580 of βig-h3 was an essential motif for the adhesion and growth of VSMCs. Interaction between the YH18 motif and the αvβ5 integrin was responsible for the migration of VSMCs on βig-h3. Inhibitors of phosphatidylinositide 3-kinase, extracellular signal-regulated kinase (ERK), and Src kinase reduced the adhesion and migration of VSMCs on βig-h3. βig-h3 triggered phosphorylation and activation of AKT, ERK, focal adhesion kinase, and paxillin mediating the adhesion and migration of VSMCs. Taken together, these results suggest that βig-h3 and αvβ5 integrin play a role in the adhesion and migration of VSMCs during the pathogenesis of atherosclerosis.