RhoA-Rho kinase signaling pathway mediates adventitial fibroblasts differentiation to myofibroblasts induced by TGF-β1.

Vascular adventitial fibroblasts (AF) differentiation to myofibroblasts (MF) is the critical physiopathologic feature of vascular remodeling. This study was to investigate the role of RhoA-Rho kinase signaling pathway in AF differentiation to MF induced by transforming growth factor β1 (TGF-β1). The results showed that TGF-β1 up-regulated total RhoA protein expression and RhoA activity in cultured AF by Western blotting and Rho pull-down assay, respectively. TGF-β1 up-regulated phospho-Myosin phosphatase target subunit (MYPT1, a downstream substrate of Rho kinase) expression without altering Rho kinase protein expression, indicating TGF-β1 induced the enhancement of activity of Rho kinase. Ad-N19RhoA-hrGFP virus infection and Y27632, a specific inhibitor of Rho kinase, dose-dependently inhibited TGF-β1-induced α-SM-actin and Calponin expression, as markers of MF differentiation. In conclusion, the RhoA-Rho kinase pathway is involved in AF differentiation to MF induced by TGF-β1.