Rho-kinase Contributes to Sustained RhoA Activation through Phosphorylation of p190A RhoGAP
Rho-kinase Contributes to Sustained RhoA Activation through Phosphorylation of p190A RhoGAP
复制标题
DOI：
10.1074/jbc.m806853200
复制
发表时间：
2009-02-20
影响因子：
4.8
通讯作者：
Kaibuchi, Kozo
中科院分区：
文献类型：
--
作者：
Mori, Kazutaka;Amano, Mutsuki;Kaibuchi, Kozo
RhoA在血管平滑肌细胞中被特异性细胞外信号如内皮素-1（ET-1）瞬时激活。RhoGAP负调节RhoA活性：因此，RhoA成为GDP结合的无活性形式。RhoA的持续激活是由高剂量的细胞外信号诱导的，并且与某些疾病如血管痉挛有关。然而，它仍然在很大程度上是未知的，如何延长激活RhoA诱导。在这里，我们表明，Rho激酶，RhoA的效应，磷酸化p190 A RhoGAP在Ser（1150）和减弱p190 A RhoGAP活性在COS 7细胞。Rnd与p190 A RhoGAP的结合被认为增强了其活化。通过Rho激酶磷酸化p190 A RhoGAP损害Rnd结合。用高剂量的ET-1刺激血管平滑肌细胞引起持续的RhoA激活和p190 A RhoGAP磷酸化，这两者都被Rho激酶抑制剂抑制。p190 A RhoGAP的磷酸化突变减弱了Rnd结合和RhoGAP活性。总之，这些结果表明，ET-1诱导Rho激酶激活和随后的p190 A RhoGAP磷酸化，导致RhoA激活延长。
RhoA is transiently activated by specific extracellular signals such as endothelin-1 (ET-1) in vascular smooth muscle cells. RhoGAP negatively regulates RhoA activity: thus, RhoA becomes the GDP-bound inactive form afterward. Sustained activation of RhoA is induced with high doses of the extracellular signals and is implicated in certain diseases such as vasospasms. However, it remains largely unknown how prolonged activation of RhoA is induced. Here we show that Rho-kinase, an effector of RhoA, phosphorylated p190A RhoGAP at Ser(1150) and attenuated p190A RhoGAP activity in COS7 cells. Binding of Rnd to p190A RhoGAP is thought to enhance its activation. Phosphorylation of p190A RhoGAP by Rho-kinase impaired Rnd binding. Stimulation of vascular smooth muscle cells with a high dose of ET-1 provoked sustained RhoA activation and p190A RhoGAP phosphorylation, both of which were prohibited by a Rho-kinase inhibitor. The phosphomimic mutation of p190A RhoGAP weakened Rnd binding and RhoGAP activities. Taken together, these results suggest that ET-1 induces Rho-kinase activation and subsequent phosphorylation of p190A RhoGAP, leading to prolonged RhoA activation.