Endogenous RhoG is dispensable for integrin-mediated cell spreading but contributes to Rac-independent migration
Endogenous RhoG is dispensable for integrin-mediated cell spreading but contributes to Rac-independent migration
复制标题
DOI：
10.1242/jcs.025130
复制
发表时间：
2008-06-15
影响因子：
4
通讯作者：
Schwartz, Martin Alexander
中科院分区：
文献类型：
--
作者：
Meller, Julia;Vidali, Luis;Schwartz, Martin Alexander
由整合素激活的RAC对于细胞的扩散、迁移、生长和存活是必不可少的。主要基于显性失活突变体的过表达，已提出RhoG介导埃尔莫和Dock 180上游的整合素依赖性Rac活化。然而，RhoG基因敲除小鼠没有表现出明显的发育或功能异常。为了阐明RhoG在整合素介导的信号传导中的作用，我们开发了RhoG特异性抗体，其与shRNA介导的敲除一起允许分析内源性蛋白。尽管显性负性构建体的显著作用，但几乎完全的RhoG耗尽基本上不抑制细胞粘附、扩散、迁移或Rac活化。此外，RhoG没有被粘附到纤连蛋白上而被可检测地激活。使用Rac 1（-/-）细胞，我们发现，组成型活性RhoG通过Rac依赖和非依赖途径诱导膜皱褶。此外，内源性RhoG对于Rac非依赖性细胞迁移是重要的。然而，即使在这些细胞中，RhoG也没有显著促进细胞铺展。因此，这些数据阐明了RhoG在整合素信号传导和细胞运动中的作用。
Rac activation by integrins is essential for cell spreading, migration, growth and survival. Based mainly on overexpression of dominant-negative mutants, RhoG has been proposed to mediate integrin-dependent Rac activation upstream of ELMO and Dock180. RhoG-knockout mice, however, display no significant developmental or functional abnormalities. To clarify the role of RhoG in integrin-mediated signaling, we developed a RhoG-specific antibody, which, together with shRNA-mediated knockdown, allowed analysis of the endogenous protein. Despite dramatic effects of dominant-negative constructs, nearly complete RhoG depletion did not substantially inhibit cell adhesion, spreading, migration or Rac activation. Additionally, RhoG was not detectably activated by adhesion to fibronectin. Using Rac1(-/-) cells, we found that constitutively active RhoG induced membrane ruffling via both Rac-dependent and -independent pathways. Additionally, endogenous RhoG was important for Rac-independent cell migration. However, RhoG did not significantly contribute to cell spreading even in these cells. These data therefore clarify the role of RhoG in integrin signaling and cell motility.