Tyrosine phosphorylation of β2-chimaerin by Src-family kinase negatively regulates its Rac-specific GAP activity
Tyrosine phosphorylation of β2-chimaerin by Src-family kinase negatively regulates its Rac-specific GAP activity
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DOI：
10.1016/j.bbamcr.2007.05.004
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发表时间：
2007-09-01
影响因子：
5.1
通讯作者：
Sakane, Fumio
中科院分区：
文献类型：
--
作者：
Kai, Masahiro;Yasuda, Satoshi;Sakane, Fumio
β2-嵌合体是第二信使二酰甘油和佛波酯的胞内受体，是RAE的GTP酶激活蛋白(GAP)。β2-嵌合体负性控制许多RAC依赖的病理生理事件，包括肿瘤的发展。然而，β2-嵌合体的调控机制在很大程度上仍不清楚。在此，我们报道了在表皮生长因子(EGF)的刺激下，β2嵌合体被Src家族蛋白(SFKs)酪氨酸磷酸化。突变分析表明，N端调控区的Tyr-21是一个主要的磷酸化位点。有趣的是，添加SFK抑制剂和用Phe(Y21F)取代Tyr-21显著增强了EGF处理的细胞中β2-嵌合体的RAC-GAP活性。此外，Y21F突变体比野生型β2嵌合体更能抑制整合素依赖的细胞扩散，而rac1在其中起关键作用。这些结果表明，Tyr-21的磷酸化是一种新的、依赖于SFK的机制，它负向调节β2-嵌合体RAC-GAP的活性。(C)2007 Elsevier B.V.保留所有权利。
beta 2-Chimaerin, an intracellular receptor for the second messenger diacylglycerol and phorbol esters, is a GTPase-activating protein (GAP) specific for Rae. beta 2-Chimaerin negatively controls many Rac-dependent pathophysiological events including tumor development. However, the regulatory mechanism of beta 2-chimaerin remains largely unknown. Here we report that beta 2-chimaerin is tyrosine-phosphorylated by Src-family kinases (SFKs) upon cell stimulation with epidermal growth factor (EGF). Mutational analysis identified Tyr-21 in the N-terminal regulatory region as a major phosphorylation site. Intriguingly, the addition of SFK inhibitor and the replacement of Tyr-21 with Phe (Y21F) markedly enhanced Rac-GAP activity of beta 2-chimaerin in EGF-treated cells. Moreover, the Y21F mutant inhibited integrin-dependent cell spreading, in which Rac1 plays a critical role, more strongly than wild-type beta 2-chimaerin. These results suggest Tyr-21 phosphorylation as a novel, SFK-dependent mechanism that negatively regulates beta 2-chimaerin Rac-GAP activity. (C) 2007 Elsevier B.V. All rights reserved.