The first CH domain of affixin activates Cdc42 and Rac1 through αPIX, a Cdc42/Rac1-specific guanine nucleotide exchanging factor
The first CH domain of affixin activates Cdc42 and Rac1 through αPIX, a Cdc42/Rac1-specific guanine nucleotide exchanging factor
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DOI：
10.1111/j.1356-9597.2004.00717.x
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发表时间：
2004-03-01
期刊：
影响因子：
2.1
通讯作者：
Ishigatsubo, Y
中科院分区：
文献类型：
--
作者：
Mishima, W;Suzuki, A;Ishigatsubo, Y
Rho GTP酶，CDC42和rac1，通过有效地整合细胞-底物黏附和肌动蛋白聚合，在细胞迁移中发挥关键作用。虽然有人认为整合素通过一些整合素结合蛋白，如粘着斑激酶(FAK)和帕西林来激活这些Rho GTP酶，但确切的分子机制在很大程度上还不清楚。在这项研究中，我们证明了与整合素连接蛋白(ILK)结合的蛋白AFIXIN的第一个CH结构域(CH1)相对应的RP1的过表达通过激活CDC42/rac1诱导了MDCK细胞中显著的肌动蛋白重组。Affisin全长和RP1与CDc42/rac1特异性的鸟嘌呤核苷酸交换因子Alphapix共沉淀，并共同定位于运动细胞的片状脂膜顶端。Alphapix的点突变体Alphapix(L383R，L384S)具有显著的显性负效应，表明Alphapix参与了RP1诱导的CDC42的激活。我们的数据有力地支持了ILK和AFIXIN提供了一条新的信号通路，将整合素信号与CDC42/rac1激活联系起来。
Rho GTPases, Cdc42 and Rac1, play pivotal roles in cell migration by efficiently integrating cell-substrate adhesion and actin polymerization. Although it has been suggested that integrins stimulate these Rho GTPases via some of integrin binding proteins such as focal adhesion kinase (FAK) and paxillin, the precise molecular mechanism is largely unknown. In this study, we showed that the over-expression of RP1 corresponding to the first CH domain (CH1) of affixin, an integrin-linked kinase (ILK)-binding protein, induced a significant actin reorganization in MDCK cells by activating Cdc42/Rac1. Affixin full length and RP1 co-immunoprecipitated with alphaPIX, a Cdc42/Rac1-specific guanine nucleotide exchanging factor (GEF), and they co-localized at the tips of lamellipodia in motile cells. The involvement of alphaPIX in the RP1-induced Cdc42 activation was demonstrated by the significant dominant negative effect of a point mutant of alphaPIX, alphaPIX (L383R, L384S), lacking GEF activity. Our data strongly support that ILK and affixin provide a novel signalling pathway that links integrin signalling to Cdc42/Rac1 activation.