A critical role for phosphatidylinositol (3,4,5)-trisphosphate-dependent Rac exchanger 1 in endothelial junction disruption and vascular hyperpermeability.
A critical role for phosphatidylinositol (3,4,5)-trisphosphate-dependent Rac exchanger 1 in endothelial junction disruption and vascular hyperpermeability.
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DOI：
10.1161/circresaha.112.273078
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发表时间：
2012-12-07
影响因子：
20.1
通讯作者：
Ye RD
中科院分区：
文献类型：
--
作者：
Naikawadi RP;Cheng N;Vogel SM;Qian F;Wu D;Malik AB;Ye RD
小分子GTP酶Rac对血管内皮细胞功能至关重要，但其在血管内皮细胞中的调控尚不清楚。了解上游通路可能描述RAC的激活机制及其在维持血管内皮屏障完整性中的作用。通过研究P-REx1，一种先前已知的G蛋白偶联受体(GPCR)信号转导的RAC特异性鸟嘌呤核苷酸交换因子(GEF)，我们试图确定RAC-环境基金是否是信号整合的节点和药物干预的潜在靶点。采用基因缺失和siRNA沉默的方法，研究P-Rex1在肺微血管内皮细胞中的作用。肿瘤坏死因子-α暴露导致内皮细胞连接的破坏，并沉默P-Rex1保护的连接完整性。肿瘤坏死因子-α以P-Rex1依赖的方式刺激Rac的激活和ROS的产生。去除P-Rex1可显著降低肿瘤坏死因子-α攻击小鼠肺组织中ICAM-1的表达、中性粒细胞跨内皮细胞迁移和白细胞的滞留。在脂多糖诱导的脓毒症模型中，P-REx1基因敲除小鼠对肺血管高通透性和水肿也是无效的。这些结果首次证明，在内皮细胞中表达的P-Rex1是在肿瘤坏死因子-α下游激活的，而不是一种gpr激动剂。我们的数据表明P-REx1是血管屏障破坏的关键介质。靶向P-Rex1可以有效地对抗肿瘤坏死因子-α和脂多糖诱导的内皮连接破坏和血管高通透性。
The small GTPase Rac is critical to vascular endothelial functions, yet its regulation in endothelial cells remains unclear. Understanding the upstream pathway may delineate Rac activation mechanisms and its role in maintaining vascular endothelial barrier integrity. By investigating P-Rex1, one of the Rac-specific guanine nucleotide exchange factors (GEFs) previously known for G protein-coupled receptor (GPCR) signaling, we sought to determine whether Rac-GEF is a nodal for signal integration and potential target for drug intervention. Using gene deletion and siRNA silencing approach, we investigated the role of P-Rex1 in lung microvascular endothelial cells (HLMVECs). TNF-α exposure led to disruption of endothelial junctions, and silencing P-Rex1 protected junction integrity. TNF-α stimulated Rac activation and ROS production in a P-Rex1-dependent manner. Removal of P-Rex1 significantly reduced ICAM-1 expression, PMN transendothelial migration and leukocyte sequestration in TNF-α challenged mouse lungs. The P-Rex1 knockout mice were also refractory to lung vascular hyper-permeability and edema in a LPS-induced sepsis model. These results demonstrate for the first time that P-Rex1 expressed in endothelial cells is activated downstream of TNF-α, which is not a GPCR agonist. Our data identify P-Rex1 as a critical mediator of vascular barrier disruption. Targeting P-Rex1 may effectively protect against TNF-α and LPS-induced endothelial junction disruption and vascular hyper-permeability.