Reactive Oxygen Species and Endothelial Migration

内皮细胞(EC)迁移是内皮损伤修复和血管生成的关键事件。血管内皮生长因子是一个 主要通过血管内皮生长因子2型受体(VEGFR2)促进内皮细胞迁移。在静止的ECS中， 血管内皮生长因子刺激内皮细胞迁移的最初反应之一是稳定的细胞-细胞松动 VE-钙粘蛋白酪氨酸磷酸化调节的接触。我们发现，血管内皮生长因子可以刺激 基于rac1依赖gp91Phox的NAD(P)H氧化酶和活性氧自由基(ROS)参与 VEGFR2介导的与EC迁移相关的信号转导。潜在的分子机制很差 明白了。我们最近发现IQGAP1是一个新的VEGFR2结合蛋白。它起着脚手架的作用 通过与细胞骨架和细胞间黏附相互作用来控制细胞运动和形态发生的蛋白质 蛋白质包括活性的rac1和E-钙粘附素。我们还发现：1)IQGAP1的表达在 新生毛细血管内皮细胞在小鼠后肢缺血血管生成模型中的表达 IQGAP1促进内皮细胞基本的rac1活性、ROS的产生和细胞迁移；3)VEGF促进 在黏附连接将激活的VEGFR2和rac1募集到IQGAP1-VE-钙粘素复合体， 这可能促进依赖ROS的细胞-细胞接触的丧失和随后的EC迁移；4)创伤 分析表明，IQGAP1与活性的VEGFR2和gp91Phox在前沿被动地共定位 正在迁移EC。因此，我们假设IQGAP1作为VEGFR2结合的支架蛋白来连接 ROS依赖的信号与血管内皮生长因子介导的内皮迁移。AIM1将检查IQGAP1是否 在功能上与VEGFR2和rac1相互作用，将VEGFR2与ROS依赖的信号连接到EC 迁移。AIM2将检查IQGAP1是否作为支架招募激活的VEGFR2和rac1 TO通过与VE-钙粘附素结合来黏附连接，从而促进细胞-细胞内ROS依赖性的丢失 联系人，这会启动EC迁移。Aim3将研究IQGAP1在靶向中的支架作用 在细胞定向迁移过程中，VEGFR2和NAD(P)H氧化酶被转移到前沿。AIM4将评估 IQGAP1在小鼠后肢缺血模型体内的功能意义。长期目标是 了解ROS在血管生成背景下调节EC迁移的分子机制 和内皮伤口修复，这应该有助于开发新的治疗策略。

Endothelial cell (EC) migration is a key event for endothelial wound repair and angiogenesis. VEGF is a potent stimulator for EC migration primarily through the VEGF type2 receptor (VEGFR2). In quiescent ECs, one of the initial responses to stimulate endothelial migration by VEGF is the loosening of stable cell-cell contacts which is regulated by tyrosine phosphorylation of VE-cadherin. We showed that VEGF stimulates Rac1-dependent gp91phox-based NAD(P)H oxidase and that reactive oxygen species (ROS) are involved in VEGFR2-mediated signaling linked to EC migration. Underlying molecular mechanisms are poorly understood. We recently identified IQGAP1 as a novel VEGFR2 binding protein. It functions as a scaffold protein that controls cell motility and morphogenesis by interacting with cytoskeletal and cell-cell adhesion proteins including active Rac1 and E-cadherin. We also found that: 1) IQGAP1 expression is increased in the newly-formed capillary ECs in a mouse hindlimb ischemia model of angiogenesis; 2) Overexpression of IQGAP1 increases basal Rac1 activity, ROS production and cell migration in ECs; 3) VEGF promotes recruitment of activated VEGFR2 and Rac1 to the IQGAP1-VE-cadherin complex at adherens junctions, which may promote ROS-dependent loss of cell-cell contacts and subsequent EC migration; 4) Wound assays reveal that IQGAP1 colocalizes with active VEGFR2 and gp91phox at the leading edge inactively migrating ECs. We thus hypothesize that IQGAP1 functions as a VEGFR2 binding scaffold protein to link ROS-dependent signaling with VEGF-mediated endothelial migration. Aim1 will examine whether IQGAP1 functionally interacts with VEGFR2 and Rac1 to couple VEGFR2 to ROS-dependent signaling linked to EC migration. Aim2 will examine whether IQGAP1 functions as a scaffold to recruit activated VEGFR2 and Rac1 to adherens junctions through binding to VE-cadherin, thereby facilitating ROS-dependent loss of cell-cell contacts, which initiates EC migration. Aim3 will examine the scaffolding role of IQGAP1 in targeting VEGFR2 and NAD(P)H oxidase to the leading edge during directed cell migration. Aim4 will assess the functional significance of IQGAP1 in vivo using mouse hindlimb ishcemia model. The long-term goal is to understand the molecular mechanisms by which ROS regulate EC migration in the context of angiogenesis and endothelial wound repair, which should facilitate the development of new therapeutic strategies.