Effect of Myosin without Phosphorylation on the Migration of Vascular Smooth Muscle Cells induced by Platelet-derived Growth Factor

Abstract: In order to demonstrate the effect of myosin without phosphorylation on the migration of smooth muscle cells， we investigated myosin without phosphorylation whether involved in the migration of GbaSM-4 cells induced by platelet-derived growth factor (PDGF). It was found that lower 20 ng/ml PDGF was able to induce the migration of GbaSM-4 cells， in which myosin light chain (MLC20) with phosphorylation was not necessary. The migration can be depressed by blebbistatin， a specific inhibitor of myosin. The phosphorylation of MLC20 was downregulated in the GbaSM-4 cells by RNA interference (RNAi) targeting myosin light chain kinase (MLCK)， examined by Western blot analysis. Moreover， PDGF still was able to induce the migration when RNAi was used， which could be blocked by blebbistatin. The ATPase activity assay for myosin in smooth muscle cells in vitro showed that blebbistatin was able to inhibit the ATPase activity of myosin without phosphorylation in smooth muscle cells. The target was mainly localized at the head of myosin S1. The data demonstrated that the non-phosphorylated myosin may involved in the migration of vascular smooth muscle cells induced by PDGF.

CSTR: 32200.14.cjcb.2007.01.0015