Vascular smooth muscle cells promote endothelial cell adhesion via microtubule dynamics and activation of paxillin and the extracellular signal-regulated kinase (ERK) pathway in a co-culture system

Interaction between endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) plays an important role in vascular biology. Cell adhesion to the extracellular matrix provides critical environmental information necessary for cell migration, proliferation, differentiation and survival. In this study, the role of VSMCs in EC adhesion was demonstrated by using a co-culture system. It was shown that the co-cultured VSMCs significantly increased the number of adherent ECs, and induced an increase of total focal adhesion area in ECs. These changes were associated with a low microtubule-to-tubulin ratio, and activation of extracellular signal-regulated kinase (ERK) and paxillin. Both the EC adhesion state and activation of the ERK/paxillin pathway by the co-cultured VSMCs could be inhibited by trichostatin A (TSA). As an inhibitor of histone deacetylase, TSA acts by modulating microtubule polymerization state. Taken together, these data suggest that the co-cultured VSMCs promote EC adhesion by modulating the microtubule cytoskeleton polymerization state, which in turn activates the ERK pathway and up-regulates phosphorylated paxillin expression to accelerate focal adhesion formation.