Non-redundant roles of the Gab1 and Gab2 scaffolding adapters in VEGF-mediated signalling, migration, and survival of endothelial cells
Non-redundant roles of the Gab1 and Gab2 scaffolding adapters in VEGF-mediated signalling, migration, and survival of endothelial cells
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DOI：
10.1016/j.cellsig.2009.02.004
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发表时间：
2009-06-01
影响因子：
4.8
通讯作者：
Royal, Isabelle
中科院分区：
文献类型：
--
作者：
Caron, Christine;Spring, Kathleen;Royal, Isabelle
此前，GAB1被认为是血管内皮生长因子(VEGF)对Akt、Src、ERK1/2、内皮细胞迁移和毛细血管形成的正向调节因子。然而，它在内皮细胞存活中的作用，以及另一个家族成员Gab2对信号和生物反应的潜在贡献仍然未知。在这里，我们证明了Gab2是激活的血管内皮生长因子受体-2(VEGFR2)下游依赖于Grb2的酪氨酸磷酸化，它与包括PI3K和SHP2在内的信号蛋白有关，但显然与受体无关。与GAB1类似，过度表达Gab2可诱导内皮细胞迁移以响应血管内皮生长因子，而使用siRNAs耗尽Gab2会导致内皮细胞迁移减少。重要的是，GAB1和Gab2的缺失会导致对血管内皮生长因子诱导的细胞迁移的更大抑制。然而，与已报道的GAB1相反，沉默Gab2导致Src、Akt和ERK1/2活性增加，p38磷酸化略有降低，GAB1蛋白水平上调。因此，在Gab2-/-成纤维细胞中重新表达Gab2会导致相反的结果，这表明在这些条件下Gab2和GAB1表达的调节可能导致观察到的信号受损。与它们在Akt上的相反作用一致，GAB1的缺失而不是Gab2的缺失导致FOXO1磷酸化和血管内皮细胞生长因子介导的内皮细胞存活减少。VEGFR2 Y801和Y1214基因突变使GAB1的磷酸化丧失，也与Akt的抑制有关。总之，这些结果强调了GAB1和GAB2在内皮细胞中的非冗余和基本作用，并表明这些蛋白在体内血管生成中的主要贡献。(C)2009 Elsevier Inc.保留所有权利。
Gab1 was previously described as a positive modulator of Akt, Src, ERK1/2, endothelial cell migration, and capillary formation in response to vascular endothelial growth factor (VEGF). However, its involvement in endothelial cell survival, as well as the potential contribution of the other family member Gab2 to signalling and biological responses remained unknown. Here, we show that Gab2 is tyrosine phosphorylated in a Grb2-dependent manner downstream of activated VEGF receptor-2 (VEGFR2), and that it associates with signalling proteins including PI3K and SHP2, but apparently not with the receptor. Similarly to Gab1, over-expression of Gab2 induces endothelial cell migration in response to VEGF, whereas its depletion using siRNAs results in its reduction. Importantly, depletion of both Gab1 and Gab2 leads to an even greater inhibition of VEGF-induced cell migration. However, contrary to what has been reported for Gab1, the silencing of Gab2 results in increased Src, Akt and ERK1/2 activation, slightly reduced p38 phosphorylation, and up-regulation of Gab1 protein levels. Accordingly, re-expression of Gab2 in Gab2-/- fibroblasts leads to opposite results, suggesting that the modulation of both Gab2 and Gab1 expression in these conditions might contribute to the impaired signalling observed. Consistent with their opposite roles on Akt, the depletion of Gab1, but not of Gab2, results in reduced FOXO1 phosphorylation and VEGF-mediated endothelial cell survival. Mutation of VEGFR2 Y801 and Y1214, which abrogates the phosphorylation of Gab1, also correlates with inhibition of Akt. Altogether, these results underscore the non-redundant and essential roles of Gab1 and Gab2 in endothelial cells, and suggest major contributions of these proteins during in vivo angiogenesis. (C) 2009 Elsevier Inc. All rights reserved.