Integrins regulate GTP-Rac localized effector interactions through dissociation of Rho-GDI
Integrins regulate GTP-Rac localized effector interactions through dissociation of Rho-GDI
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DOI：
10.1038/ncb759
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发表时间：
2002-03-01
影响因子：
21.3
通讯作者：
Schwartz, MA
中科院分区：
文献类型：
--
作者：
Del Pozo, MA;Kiosses, WB;Schwartz, MA
Rho GTP酶的正常功能需要对效应器相互作用进行精确的空间和时间调节。整合素介导的细胞黏附通过控制GTP-RAC膜靶向调控GTP-RAC与其效应分子的相互作用。在这里，我们证明了GTP-RAC到膜的移位不依赖于效应器的相互作用，而是需要靠近羧基末端的多碱序列。CDC42还需要整合素介导的黏附来转位到膜上。最近发展的基于荧光共振能量转移(FRET)的分析得出了令人惊讶的结果，尽管V12-RAC分布均匀，但激活的V12-RAC与可溶的细胞质效应域的相互作用在细胞边缘附近的特定区域增强，并由整合素刺激局部诱导。这种增强需要RAC膜靶向。我们发现，与细胞质GTP-RAC相关的Rho-GDI可以阻断效应器结合。膜转位后Rho-GDI的释放使Rac能够与效应器结合。因此，Rho-GDI对RAC-效应器相互作用提供了空间受限的调节。
The proper function of Rho GTPases requires precise spatial and temporal regulation of effector interactions. Integrin-mediated cell adhesion modulates the interaction of GTP-Rac with its effectors by controlling GTP-Rac membrane targeting. Here, we show that the translocation of GTP-Rac to membranes is independent of effector interactions, but instead requires the polybasic sequence near the carboxyl terminus. Cdc42 also requires integrin-mediated adhesion for translocation to membranes. A recently developed fluorescence resonance energy transfer (FRET)-based assay yields the surprising result that, despite its uniform distribution, the interaction of activated V12-Rac with a soluble, cytoplasmic effector domain is enhanced at specific regions near cell edges and is induced locally by integrin stimulation. This enhancement requires Rac membrane targeting. We show that Rho-GDI, which associates with cytoplasmic GTP-Rac, blocks effector binding. Release of Rho-GDI after membrane translocation allows Rac to bind to effectors. Thus, Rho-GDI confers spatially restricted regulation of Rac-effector interactions.