Gab1 contributes to cytoskeletal reorganization and chemotaxis in response to platelet-derived growth factor
Gab1 contributes to cytoskeletal reorganization and chemotaxis in response to platelet-derived growth factor
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DOI：
10.1074/jbc.m312996200
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发表时间：
2004-04-23
影响因子：
4.8
通讯作者：
Heldin, CH
中科院分区：
文献类型：
--
作者：
Kallin, A;Demoulin, JB;Heldin, CH
Gab1是一种支架/对接蛋白，已被认为在某些质膜受体下游的信号转导中发挥作用，包括血小板衍生生长因子（PDGF）受体。我们发现PDGF诱导Gab1快速磷酸化，这依赖于Grb2的募集，表明Grb2是Gab1和PDGF β受体之间的桥梁。PDGF还增强了Gab1与磷酸酶SHP-2的结合，但没有增强与p85的结合。为了进一步研究Gab1在PDGF信号传导中的作用，我们用多西环素诱导的Gab1构建物转染了猪主动脉内皮细胞。Gab1表达的增加增强了SHP-2的募集和激活，以及PDGF对丝裂原活化蛋白激酶Erk和p38的磷酸化。Gab1的表达也促进了板足和细胞突起的形成。在Gab1缺陷小鼠胚胎成纤维细胞中，通过恢复野生型Gab1的表达，而不是无法与SHP-2关联的突变Gab1，诱导了相同的表型。PDGF对肌动蛋白细胞骨架的这些作用不会因p38或Erk的抑制而改变，但可以被Rac的显性阴性形式阻断（Asn(17)）。最后，与野生型细胞相比，gab1缺陷成纤维细胞对PDGF梯度的趋化反应减弱。综上所述，Gab1在PDGF β受体下游的丝裂原活化蛋白激酶Erk和p38的调控中发挥选择性作用，并在PDGF反应中参与细胞骨架重组和趋化。
Gab1 is a scaffolding/docking protein that has been suggested to play a role in signal transduction downstream of certain plasma membrane receptors, including platelet-derived growth factor (PDGF) receptors. We found that PDGF induced a rapid Gab1 phosphorylation, which depended on the recruitment of Grb2, indicating that Grb2 acts as a bridge between Gab1 and the PDGF beta-receptor. PDGF also enhanced the binding of Gab1 to the phosphatase SHP-2, but not to p85. To further study the role of Gab1 in PDGF signaling, we transfected porcine aortic endothelial cells with a doxycycline-inducible Gab1 construct. Increased Gab1 expression enhanced the recruitment and activation of SHP-2, as well as the phosphorylation of the mitogen-activated protein kinases Erk and p38 by PDGF. Gab1 expression also enhanced the formation of lamellipodia and cellular protrusions. In Gab1-deficient mouse embryonic fibroblasts, the same phenotype was induced by restoring the expression of wild-type Gab1, but not a mutant Gab1 that was unable to associate with SHP-2. These effects of PDGF on the actin cytoskeleton were not altered by the inhibition of p38 or Erk, but could be blocked by a dominant-negative form of Rac (Asn(17)). Finally, Gab1-deficient fibroblasts showed a decreased chemotactic response toward gradients of PDGF as compared with wild-type cells. In conclusion, Gab1 plays a selective role in the regulation of the mitogen-activated protein kinases Erk and p38 downstream of the PDGF beta-receptor, and contributes to cytoskeletal reorganization and chemotaxis in response to PDGF.