Rac2 in Pulmonary Microvascular Endothelial Cells

描述（由申请人提供）：Rac2是gtp酶Rac家族的一员，通常由造血细胞表达。我们最近的研究表明，Rac2 mRNA和蛋白在肺微血管内皮细胞中以颗粒状形式在核周中心区表达，Rac2调节血管通透性，增强正常肺的屏障功能，补体活化诱导肺通透性增加需要Rac2，内皮细胞Rac2表达受TNF-a调节。我们提出的研究将有助于更好地理解GTPase在肺通透性和炎症中的重要作用，通过测试工作假设，即内皮细胞中表达的Rac2通过调节囊泡运输和/或内皮细胞边界的完整性来调节健康肺部的流体通量和内皮细胞损伤中血管通透性的增加，以及其活性和表达在先天免疫反应中被调节。目的1将确定Rac2如何调节正常肺部的液体通量。测量肺血管外水，比较Rac2缺失型和野生型小鼠的白蛋白积累率，评估内皮细胞或其他肺实质细胞表达Rac2的情况，确定Rac2是否通过连接复合物或囊泡运输系统的改变来调节流体通量。目的2将确定在内皮细胞损伤期间Rac2是如何被激活的。我们将研究ICAM-1连接、活性氧和/或C5b-9复合物（膜攻击复合物）沉积在体内和体外启动Rac2激活中的作用，以及导致Rac2激活的细胞内信号通路。目的3将确定TNF-a和其他细胞因子如何调节Rac2。我们将评估TNF-a、IL-1和干扰素-g在体内和体外对内皮细胞Rac2的产生和激活是否有相似的影响，以及细胞因子诱导的信号通路的作用。细胞因子诱导的损伤在体内和体外是否需要内皮细胞Rac2也将被确定。这些研究将有助于了解内皮细胞Rac2在损伤时增强屏障功能、调节通透性等宿主防御方面的作用。

DESCRIPTION (provided by applicant): Rac2 is a member of the Rac family of GTPases commonly expressed by cells of hematopoietic origin. Our recent studies suggest that Rac2 mRNA and protein is expressed by pulmonary microvascular endothelial cells in a granular pattern within the central perinuclear region, that Rac2 regulates the vascular permeability and enhances the barrier function of normal lungs, that Rac2 is required for increases in pulmonary permeability induced by complement activation, and that endothelial Rac2 expression is regulated by TNF-a. The proposed studies will help to better understand the important roles of this GTPase in lung permeability and inflammation by testing the working hypothesis that Rac2 expressed in endothelial cells modulates fluid flux in healthy lungs and increased vascular permeability in endothelial cell injury by regulating vesicular transport and/or integrity of the endothelial cell borders, and that its activity and expression are modulated during the innate immune response. Aim 1 will determine how Rac2 regulates fluid flux in normal lungs. Extravascular lung water will be measured, the rate of albumin accumulation will be compared in Rac2 deficient and wild type mice, which endothelial cells or other lung parenchymal cells express Rac2 will be evaluated, and whether Rac2 modulates fluid fluxes through changes in the junctional complexes or the vesicular transport system will be determined. Aim 2 will determine how Rac2 is activated during endothelial cell injury. The role of ICAM-1 ligation, reactive oxygen species, and/or deposition of C5b-9 complexes (membrane attack complexes) in initiating Rac2 activation in vivo and in vitro will be examined, as well as the intracellular signaling pathways that lead to Rac2 activation. Aim 3 will determine how TNF-a and other cytokines regulate Rac2. Whether TNF-a, IL-1 and interferon-g all have similar effects on endothelial Rac2 production and activation in vivo and in vitro will be assessed, as well as the role of cytokine-induced signaling pathways. Whether endothelial Rac2 is required for cytokine-induced injury in vivo and in vitro will also be determined. These studies will help to understand the role of endothelial cell Rac2 in enhancing the barrier function and in regulating permeability and other aspects of host defense during injury.