Rac2 in Pulmonary Microvascular Endothelial Cells

描述（由申请人提供）：Rac 2是通常由造血来源的细胞表达的GTP酶的Rac家族的成员。我们最近的研究表明，Rac 2 mRNA和蛋白质由肺微血管内皮细胞在中央核周区域内以颗粒模式表达，Rac 2调节血管通透性并增强正常肺的屏障功能，Rac 2是由补体激活诱导的肺通透性增加所需的，并且内皮Rac 2表达受TNF-α调节。拟议的研究将有助于更好地理解这种GT3在肺渗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Rac 2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中的流体流量和内皮细胞损伤中的血管渗透性增加，并且其活性和表达在先天免疫应答期间被调节。目的1将确定Rac 2如何调节正常肺中的液体流量。将测量血管外肺水，将在Rac 2缺陷型和野生型小鼠中比较白蛋白蓄积速率，将评价表达Rac 2的内皮细胞或其他肺实质细胞，并将确定Rac 2是否通过连接复合物或囊泡转运系统的变化调节液体通量。目的2将确定Rac 2在内皮细胞损伤期间如何被激活。将检查ICAM-1连接、活性氧和/或C5 b-9复合物（膜攻击复合物）沉积在体内和体外启动Rac 2激活中的作用，以及导致Rac 2激活的细胞内信号传导途径。目的3将确定TNF-α和其他细胞因子如何调节Rac 2。将评估TNF-α、IL-1和干扰素-g是否在体内和体外对内皮细胞Rac 2的产生和活化都具有类似的作用，以及精氨酸诱导的信号传导途径的作用。还将确定内皮Rac 2是否是体内和体外精氨酸诱导的损伤所必需的。这些研究将有助于理解内皮细胞Rac 2在增强屏障功能和调节通透性以及损伤时宿主防御的其他方面的作用。

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.