Rac2 in Pulmonary Microvascular Endothelial Cells

描述(由申请人提供)：rac2是RAC家族中的一员，通常由造血细胞表达。我们最近的研究表明，在中央核周区域，肺微血管内皮细胞以颗粒状方式表达rac2的mRNA和蛋白，rac2调节血管通透性并增强正常肺的屏障功能，补体激活引起的肺通透性增加需要rac2，内皮细胞的rac2表达受肿瘤坏死因子-α的调节。这项研究将有助于更好地理解这种GTPase在肺通透性和炎症中的重要作用，因为它验证了一种工作假设，即在内皮细胞中表达的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的液体流量，并在内皮细胞损伤时增加血管通透性，并且其活性和表达在先天免疫反应中受到调节。目标1将确定rac2如何调节正常肺的液体流量。我们将测量血管外肺水，比较RAC2缺陷小鼠和野生型小鼠的白蛋白蓄积速度，评估哪些血管内皮细胞或其他肺实质细胞表达LAC 2，并确定是否通过改变连接复合体或囊泡运输系统来调节体液流量。AIM 2将确定在内皮细胞损伤过程中rac2是如何被激活的。ICAM-1的连接，活性氧物种，和/或C5b-9复合体(膜攻击复合体)的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。目标3将确定肿瘤坏死因子-a和其他细胞因子是如何调节rac2的。在体内和体外，肿瘤坏死因子-α、白细胞介素1和干扰素-g是否都对内皮细胞中的rac2的产生和激活有相似的影响，以及细胞因子诱导的信号通路的作用，将被评估。在体内和体外，细胞因子诱导的损伤是否需要内皮细胞rac2也将被确定。这些研究将有助于了解内皮细胞rac2在增强屏障功能和调节损伤时的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.