Role of the small GTPase Rap1 for integrin activity regulation in endothelial cells and angiogenesis
Role of the small GTPase Rap1 for integrin activity regulation in endothelial cells and angiogenesis
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DOI：
10.1182/blood-2008-02-138438
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发表时间：
2009-01-08
期刊：
影响因子：
20.3
通讯作者：
Chavakis, Emmanouil
中科院分区：
文献类型：
--
作者：
Carmona, Guillaume;Goettig, Stephan;Chavakis, Emmanouil
Ras 相关蛋白 1 (Rap1) 是一种小型 GTP 酶，因其参与细胞粘附的多个方面（包括整合素和钙粘蛋白介导的粘附）而引起关注。然而，Rap1 基因和 Rap1 效应器在血管生成中的作用尚未得到研究。人脐静脉内皮细胞 (HUVEC) 表达 Rap1a 和 Rap1b mRNA。为了确定 Rap1 活性对血管生成的贡献，我们过表达 Rap1GAP1，一种抑制 Rap1 活性的 GTP 酶激活蛋白。 Rap1GAP1 的过度表达显着阻断 HUVEC 的血管生成萌芽和管形成活性以及迁移和整合素依赖性粘附。 Rap1a、Rap1b 或两者的沉默可显着阻止 HUVEC 在基础和碱性成纤维细胞生长因子刺激的条件下发芽，并减少 HUVEC 迁移和整合素依赖性粘附。我们发现 Rap1a 和 Rap1b 对于内皮细胞中 β(1)-整合素的构象激活至关重要。此外，Rap1a 和 Rap1b 的沉默可阻止粘着斑激酶 (FAK) 中酪氨酸 397 的磷酸化和血管内皮生长因子诱导的 Akt1 激活。与野生型小鼠相比，Rap1a(-/-)缺陷型和Rap1a(+/-)杂合子小鼠在后肢缺血后表现出新血管形成减少。 RAPL 的沉默显着阻止了 Rap1 诱导的 HUVEC 萌芽，表明 Rap1 的血管生成活性部分是由 RAPL 介导的。我们的数据证明 Rap1 在内皮细胞和出生后新生血管形成中调节 β(1)-整合素亲和力、粘附和迁移的关键作用。 （血。2009；113：488-497）
Ras-associated protein 1 (Rap1), a small GTPase, attracted attention because of its involvement in several aspects of cell adhesion, including integrin-and cadherin-mediated adhesion. Yet, the role of Rap1 genes and of Rap1 effectors for angiogenesis has not been investigated. Human umbilical vein endothelial cells (HUVECs) express Rap1a and Rap1b mRNA. To determine the contribution of Rap1 activity for angiogenesis, we overexpressed Rap1GAP1, a GTPase-activating protein that inhibits Rap1 activity. Overexpression of Rap1GAP1 significantly blocked angiogenic sprouting and tubeforming activity of HUVECs as well as migration and integrin-dependent adhesion. Silencing of Rap1a, Rap1b, or both significantly blocked HUVECs sprouting under basal and basic fibroblast growth factor-stimulated conditions and reduced HUVEC migration and integrin-dependent adhesion. We found that Rap1a and Rap1b are essential for the conformational activation of beta(1)-integrins in endothelial cells. Furthermore, silencing of Rap1a and Rap1b prevented phosphorylation of tyrosine 397 in focal adhesion kinase (FAK) and vascular endothelial growth factor-induced Akt1-activation. Rap1a(-/-)-deficient and Rap1a(+/-) heterozygote mice displayed reduced neovascularization after hind limb ischemia compared with wild-type mice. Silencing of RAPL significantly blocked the Rap1-induced sprouting of HUVECs, suggesting that the angiogenic activity of Rap1 is partly mediated by RAPL. Our data demonstrate a critical role of Rap1 in the regulation of beta(1)-integrin affinity, adhesion, and migration in endothelial cells and in postnatal neovascularization. (Blood. 2009; 113: 488-497)