Signal-crosstalk between Rho/ROCK and c-Jun NH2-terminal kinase mediates migration of vascular smooth muscle cells stimulated by angiotensin II.

Background - Rho and its effector Rho-kinase/ROCK mediate cytoskeletal reorganization as well as smooth muscle contraction. Recent studies indicate that Rho and ROCK are critically involved in vascular remodeling. Here, we tested the hypothesis that Rho/ROCK are critically involved in angiotensin II (Ang II)- induced migration of vascular smooth muscle cells (VSMCs) by mediating a specific signal cross-talk. Methods and Results - Immunoblotting demonstrated that Ang II stimulated phosphorylation of a ROCK substrate, regulatory myosin phosphatase targeting subunit (MYPT)-1. Phosphorylation of MYPT-1 as well as migration of VSMCs induced by Ang II was inhibited by dominant-negative Rho (dnRho) or ROCK inhibitor, Y27632. Ang II - induced c-Jun NH2-terminal kinase (JNK) activation, but extracellular signal-regulated kinase (ERK) activation was not mediated through Rho/ROCK. Thus, infection of adenovirus encoding dnJNK inhibited VSMC migration by Ang II. We have further demonstrated that the Rho/ROCK activation by Ang II requires protein kinase C-delta (PKC delta) and proline-rich tyrosine kinase 2 (PYK2) activation, but not epidermal growth factor receptor transactivation. Also, VSMCs express PDZ-Rho guanine nucleotide exchange factor (GEF) and Ang II stimulated PYK2 association with tyrosine phosphorylated PDZ-RhoGEF. Conclusions - PKC delta/PYK2-dependent Rho/ROCK activation through PDZ-RhoGEF mediates Ang II - induced VSMC migration via JNK activation in VSMCs, providing a novel mechanistic role of the Rho/ROCK cascade that is involved in vascular remodeling.