Cadherin engagement inhibits RhoA via p190RhoGAP
Cadherin engagement inhibits RhoA via p190RhoGAP
复制标题
DOI：
10.1074/jbc.c200657200
复制
发表时间：
2003-04-18
影响因子：
4.8
通讯作者：
Burridge, K
中科院分区：
文献类型：
--
作者：
Noren, NK;Arthur, WT;Burridge, K
钙粘蛋白是介导上皮细胞中细胞间粘附的跨膜受体。在钙粘蛋白介导的连接形成过程中会发生许多变化，其中之一是肌动蛋白细胞骨架的重排。细胞中肌动蛋白细胞骨架动力学的关键调节因子是 GTPases 的 Rho 家族。我们在之前的研究中已经证明，钙粘蛋白信号传导会抑制 RhoA 活性并激活 Rac1。钙粘蛋白下游调节 Rho 家族蛋白活性的信号转导事件仍然未知。在这里，我们确定了 RhoA 被钙粘蛋白失活的途径。为了确定钙粘蛋白是否通过激活 RhoA 的 GTP 酶激活蛋白 (GAP) 来调节 RhoA，我们使用组成型活性 RhoA 来分离激活的 GAP。使用该测定，我们鉴定了 RhoA 特异性 GAP，p190RhoGAP，位于接合的钙粘蛋白下游。我们发现钙粘蛋白接合诱导 p190RhoGAP 酪氨酸磷酸化并增加其与 p120RasGAP 的结合。添加 PP2 可阻断 p190RhoGAP 与 63LRhoA 的沉淀增加，这表明钙粘蛋白信号传导下游需要 Src 家族激酶。钙粘蛋白对 RhoA 活性的抑制被显性失活 p190RhoGAP 的表达所拮抗。总之，这些数据表明 p190RhoGAP 活性对于钙粘蛋白使 RhoA 失活至关重要。
Cadherins are transmembrane receptors that mediate cell-cell adhesion in epithelial cells. A number of changes occur during cadherin-mediated junction formation, one of which is a rearrangement of the actin cytoskeleton. Key regulators of actin cytoskeletal dynamics in cells are the Rho family of GTPases. We have demonstrated in previous studies that cadherin signaling suppresses RhoA activity and activates Rac1. The signaling events downstream of cadherins that modulate the activity of Rho family proteins remain unknown.. Here we have identified a pathway by which RhoA becomes inactivated by cadherins. To determine whether cadherins regulate RhoA through activation of a GTPase-activating protein (GAP) for RhoA, we used constitutively active RhoA to isolate activated GAPs. Using this assay, we have identified the RhoA-specific GAP, p190RhoGAP, downstream from engaged cadherins. We found that cadherin engagement induced tyrosine phosphorylation of p190RhoGAP and increased its binding to p120RasGAP. The increased precipitation of p190RhoGAP with 63LRhoA was blocked by addition of PP2 suggesting that Src family kinases are required downstream from cadherin signaling. The inhibition of RhoA activity by cadherins was antagonized by expression of a dominant negative p190RhoGAP. Taken, together, these data demonstrate that p190RhoGAP activity is critical for RhoA inactivation by cadherins.