Plexin-B1 utilizes RhoA and Rho kinase to promote the integrin-dependent activation of Akt and ERK and endothelial cell motility
Plexin-B1 utilizes RhoA and Rho kinase to promote the integrin-dependent activation of Akt and ERK and endothelial cell motility
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DOI：
10.1074/jbc.m705467200
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发表时间：
2007-11-30
影响因子：
4.8
通讯作者：
Gutkind, J. Silvio
中科院分区：
文献类型：
--
作者：
Basile, John R.;Gavard, Julie;Gutkind, J. Silvio
脑信号蛋白是一个蛋白质家族，最初被鉴定为发育中的神经系统中的轴突引导分子，最近已被证明在多种细胞类型中调节许多细胞功能，包括运动性。我们先前已经表明，在内皮细胞中，脑信号蛋白4D通过其受体丛蛋白-B1起作用，以引起促血管生成表型，该表型涉及磷脂酰肌醇3-激酶（PI 3 K）-Akt信号通路的激活。在这里，我们通过使用受体嵌合的方法，丛蛋白-B1突变体，和显性负和药理学抑制剂，这种反应是依赖于激活的RhoA和它的下游目标，Rho激酶（ROK）。事实上，我们证明，在内皮细胞中，脑信号蛋白4D促进粘着斑复合物，应力纤维和肌球蛋白轻链的磷酸化，一个反应，这是废除了使用ROK抑制剂和缺乏细胞表达丛蛋白-B1突变体结构不能信号传导到RhoA。应力纤维聚合和收缩反过来是RhoA依赖的促血管生成信号通过丛蛋白B1所必需的。此外，我们观察到，在内皮细胞丛蛋白-B1促进整合素介导的Pyk 2的激活，导致PI 3 K，Akt和ERK的刺激。这些发现提供了证据表明丛蛋白-B1通过RhoA和ROK通过调节导致PI 3 K和Akt活化的整合素依赖性信号网络来促进内皮细胞运动。
The semaphorins are a family of proteins originally identified as axon-guiding molecules in the developing nervous system that have been recently shown to regulate many cellular functions, including motility, in a variety of cell types. We have previously shown that in endothelial cells Semaphorin 4D acts through its receptor, Plexin-B1, to elicit a pro-angiogenic phenotype that involves the activation of the phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway. Here we show through the use of a receptor chimeric approach, Plexin-B1 mutants, and dominant negative and pharmacological inhibitors that this response is dependent upon the activation of RhoA and its downstream target, Rho kinase (ROK). Indeed, we demonstrate that in endothelial cells, Semaphorin 4D promotes the formation of focal adhesion complexes, stress fibers, and the phosphorylation of myosin light chain, a response that was abolished by the use of ROK inhibitors and absent from cells expressing Plexin-B1 mutant constructs incapable of signaling to RhoA. Stress fiber polymerization and contraction are in turn necessary for RhoA-dependent pro-angiogenic signaling through Plexin-B1. Furthermore, we observed that in endothelial cells Plexin-B1 promotes the integrin-mediated activation of Pyk2, resulting in the stimulation of PI3K, Akt, and ERK. These findings provide evidence that Plexin-B1 promotes endothelial cell motility through RhoA and ROK by regulating the integrin-dependent signaling networks that result in the activation of PI3K and Akt.