MEF2A/2D参与Rho信号通路调控去极化诱导的血管平滑肌细胞分化过程

MEF2A/2D regulates depolarization induced differentiation via Rho signaling pathway in VSMCs

目的:探讨肌细胞增强因子2(MEF2)在Rho信号通路调控去极化诱导的血管平滑肌细胞分化过程中的角色。方法:原代培养小鼠门静脉血管平滑肌细胞,采用免疫荧光、Western blotting、实时荧光定量RT-PCR及siRNA技术,检测高钾去极化刺激下RhoA蛋白胞膜移位情况、LIM激酶(LIMK)和丝切蛋白2(cofilin-2)的磷酸化水平,以及MEF2四种亚型、心肌素(myocardin)以及平滑肌蛋白22α(SM22α)的mRNA表达水平。结果:高钾去极化30 s后RhoA即发生胞膜移位,而LIMK和丝切蛋白2蛋白磷酸化分别在10 min和30 min达到峰值,分别增加42.20%和32.75%(均P<0.01)。高钾刺激24 h后MEF2A和2D的mRNA表达分别增加47.63%(P<0.05)和48.15%(P<0.01)。沉默MEF2A/2D后,心肌素的表达不再对去极化敏感,但SM22α的mRNA表达不受影响。结论:MEF2A/2D通过调控心肌素参与了Rho信号通路调控去极化诱导的血管平滑肌细胞分化过程。

AIM ： To investigate the role of myocyte enhance factor 2 （MEF2） in the regulation of depolariza- tion-induced differentiation via Rho signaling pathway in vascular smooth muscle cells （VSMCs）. METHODS： In prima- rily cultured mouse portal vein VSMCs, the techniques of immunofluorescence, Western blotting, real-time RT-PCR and siRNA transfection were applied to determine the membrane translocation of RhoA, the phosphorylation of LIM kinase （LIMK） and cofilin-2, and the mRNA expression of 4 MEF2 isoforms, myocardin and SM22o~ under high KCl-induced de- polarization. RESULTS： RhoA membrane translocation occurred 30 s after depolarization, while phosphorylation of LIMK and cofilin-2 peaked at 10 min and 30 min, with increment of 42.20% and 32.75%, respectively. The mRNA expression of MEF2A and 2D was increased by 47.63% and 48.15%, respectively. In MEF2A/2D knockdown VSMCs, the mRNA expression of myocardin was not sensitive to depolarization, while SM22ct expression was not affected. CONCLUSION： MEF2A/2D, acting on myocardin, is involved in the regulation of depolarization-induced differentiation via Rho signaling pathway in VSMCs