RACK1 regulates directional cell migration by acting on Gβγ at the interface with its effectors PLCβ and PI3Kγ
RACK1 regulates directional cell migration by acting on Gβγ at the interface with its effectors PLCβ and PI3Kγ
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DOI：
10.1091/mbc.e08-04-0433
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发表时间：
2008-09-01
影响因子：
3.3
通讯作者：
Hamm, Heidi E.
中科院分区：
文献类型：
--
作者：
Chen, Songhai;Lin, Fang;Hamm, Heidi E.
细胞在趋化梯度上的迁移是由趋化因子与G蛋白偶联受体的结合以及协调的兴奋和抑制信号网络的激活介导的。虽然兴奋过程已经得到了很好的研究，抑制信号的分子本质仍然很难理解。在这里，我们报告的受体活化C激酶1（RACK 1），一种新的结合蛋白的异源三聚体G蛋白β γ（G β γ）亚基，作为一个负调控定向细胞迁移。在Jurkat和嗜中性粒细胞样分化的HL 60（dHL 60）细胞的化学引诱剂诱导的极化后，RACK 1与G β γ相互作用并被募集到前沿。RACK 1的下调显著增强细胞的趋化性，而RACK 1或保留G β γ结合能力的RACK 1片段的过表达抑制细胞迁移。进一步的研究表明，RACK 1不通过与其他已知的相互作用蛋白如PKC β和Src结合来调节细胞迁移。相反，由于RACK 1、PI 3 K γ和PLC β与G β γ的竞争性结合，RACK 1选择性地抑制G β γ刺激的磷脂酰肌醇3-激酶γ（PI 3 K γ）和磷脂酶C（PLC）β活性。总之，这些发现提供了一种调节细胞迁移的新机制，即，RACK 1介导的对趋化性关键效应物的G β γ依赖性激活的干扰。
Migration of cells up the chemoattractant gradients is mediated by the binding of chemoattractants to G protein-coupled receptors and activation of a network of coordinated excitatory and inhibitory signals. Although the excitatory process has been well studied, the molecular nature of the inhibitory signals remains largely elusive. Here we report that the receptor for activated C kinase 1 (RACK1), a novel binding protein of heterotrimeric G protein beta gamma (G beta gamma) subunits, acts as a negative regulator of directed cell migration. After chemoattractant-induced polarization of Jurkat and neutrophil-like differentiated HL60 (dHL60) cells, RACK1 interacts with G beta gamma and is recruited to the leading edge. Down-regulation of RACK1 dramatically enhances chemotaxis of cells, whereas overexpression of RACK1 or a fragment of RACK1 that retains G beta gamma-binding capacity inhibits cell migration. Further studies reveal that RACK1 does not modulate cell migration through binding to other known interacting proteins such as PKC beta and Src. Rather, RACK1 selectively inhibits G beta gamma-stimulated phosphatidylinositol 3-kinase gamma (PI3K gamma) and phospholipase C (PLC) beta activity, due to the competitive binding of RACK1, PI3K gamma, and PLC beta to G beta gamma. Taken together, these findings provide a novel mechanism of regulating cell migration, i.e., RACK1-mediated interference with G beta gamma-dependent activation of key effectors critical for chemotaxis.