Gab2 regulates cytoskeletal organization and migration of mammary epithelial cells by modulating RhoA activation.
Gab2 regulates cytoskeletal organization and migration of mammary epithelial cells by modulating RhoA activation.
复制标题
DOI：
10.1091/mbc.e10-03-0185
复制
发表时间：
2011-01-01
影响因子：
3.3
通讯作者：
Daly RJ
中科院分区：
文献类型：
--
作者：
Herrera Abreu MT;Hughes WE;Mele K;Lyons RJ;Rickwood D;Browne BC;Bennett HL;Vallotton P;Brummer T;Daly RJ
致癌信号转导子Gab 2通过下调RhoA活性调节乳腺上皮细胞的细胞骨架结构改变和细胞迁移增强。这为Gab 2在癌细胞转移中的作用提供了新的线索。对接蛋白Gab 2在包括乳腺癌在内的几种人类恶性肿瘤中过表达，并且与转移潜能增加相关。在这里，我们报告说，Gab 2在MCF-10A乳腺上皮细胞过度表达导致延迟细胞扩散，减少应力纤维和成熟的局灶性粘连，并增强细胞迁移。从14-3-3介导的负反馈解偶联的Gab 2突变体（Gab 22 ×A）的表达导致更多的间充质形态和侵袭潜力的获得。Gab 2或Gab 22 ×A的表达均导致RhoA的激活降低，但只有后者增加了Rac-GTP的水平。在MCF-10A/Gab 2细胞中组成型活性RhoA的表达恢复了应力纤维和局灶性粘连，表明Gab 2在RhoA上游信号抑制这些结构。将Shp 2的两个结合位点突变为苯丙氨酸（Gab 2 Δ Shp 2）可显著降低Gab 2对细胞表型和RhoA激活的影响。Gab 2或Gab 22 ×A（而非Gab 2 Δ Shp 2）的表达促进Vav 2磷酸化和p190 A RhoGAP的质膜募集。p190 A RhoGAP的敲除逆转了Gab 2介导的对应力纤维和局灶性粘连的影响。通过p190 A RhoGAP对RhoA负调控的Gab 2下游新途径的鉴定为Gab 2在癌症进展中的作用提供了新的线索。
The oncogenic signal transducer Gab2 mediates altered cytoskeletal organization and enhanced cell migration of mammary epithelial cells via down-regulation of RhoA activity. This sheds new light on the role of Gab2 in cancer cell metastasis. The docking protein Gab2 is overexpressed in several human malignancies, including breast cancer, and is associated with increased metastatic potential. Here we report that Gab2 overexpression in MCF-10A mammary epithelial cells led to delayed cell spreading, a decrease in stress fibers and mature focal adhesions, and enhanced cell migration. Expression of a Gab2 mutant uncoupled from 14-3-3-mediated negative feedback (Gab22×A) led to a more mesenchymal morphology and acquisition of invasive potential. Expression of either Gab2 or Gab22×A led to decreased activation of RhoA, but only the latter increased levels of Rac-GTP. Expression of constitutively active RhoA in MCF-10A/Gab2 cells restored stress fibers and focal adhesions, indicating that Gab2 signals upstream of RhoA to suppress these structures. Mutation of the two Shp2-binding sites to phenylalanine (Gab2ΔShp2) markedly reduced the effects of Gab2 on cellular phenotype and RhoA activation. Expression of Gab2 or Gab22×A, but not Gab2ΔShp2, promoted Vav2 phosphorylation and plasma membrane recruitment of p190A RhoGAP. Knockdown of p190A RhoGAP reversed Gab2-mediated effects on stress fibers and focal adhesions. The identification of a novel pathway downstream of Gab2 involving negative regulation of RhoA by p190A RhoGAP sheds new light on the role of Gab2 in cancer progression.