Regulation of NADPH Oxidase by Phospholipase D and the EC Cytoskeleton

肺内皮细胞（EC）屏障的损害由机械应力诱导， 与呼吸机诱导的肺损伤（VILI）相关，该过程导致血管通透性增加， 肺泡溢流、白细胞浸润、低氧血症以及发病率和死亡率增加。项目#3 科学家们先前已经确定了EC屏障调节的细胞骨架机制， 策略（氧化磷酸胆碱，鞘氨醇1-磷酸，生理剪切应力和循环拉伸 (CS)以及屏障破坏性机械和化学刺激（凝血酶、病理性CS）。另外这些 PPG研究者已经描述了小GTP酶Rac和Rho在血管重构中的重要作用。 EC细胞骨架和细胞接触对EC屏障调节至关重要。我们公布的结果和初步的 数据强烈表明，CS对Rac和Rho活性的幅度依赖性调节显著 影响激动剂诱导的EC渗透性变化。项目#3假设是病理性CS和 已知在VILI期间升高的血管内皮生长因子（VEGF）促进肺内皮细胞生长， 通过对Rho途径介导的EC渗透性的协同作用而导致屏障功能障碍。这些过程 通过屏障保护刺激（如肝细胞）诱导的Rac依赖性机制进行平衡 生长因子（HGF）和生理拉伸。我们推测，局灶性粘连可能作为机械传感器 并通过与Rac和Rho蛋白调节剂的特异性桩蛋白相互作用来调节小GT3活性。 具体目标#1将研究病理性CS和VEGF对Rhomediated EC屏障功能障碍。具体目标#2将确定改善残疾人状况的障碍保护战略， 通过Rho和Rac活性之间的平衡变化的VILI相关EC屏障功能障碍。 具体目标#3将通过以下方式研究机械化学因子对Rac/Rho调节的新机制： 野生型桩蛋白（或/和含有Gly 73 Ser多态性的桩蛋白）之间的相互作用 与Rac和Rho活性的调节剂（GIT 2、betaPIX、PAK 1和p190 RhoGAP）。这些研究将 揭示呼吸机诱导肺的发病机制和解决的新分子机制 损伤

Compromise of the pulmonary endothelial cell (EC) barrier is induced by mechanical stress which is associated with ventilator-induced lung injury (VILI), This process leads to increased vascular permeability, alveolar flooding, leukocyte infiltration, hypoxemia, and increased morbidity and mortality. Project #3 scientists have previously identified cytoskeletal mechanisms of EC barrier regulation by barrier-protective strategies (oxidized phosphocholine, sphingosine 1-phosphate, physiologic shear stress and cyclic stretch (CS) and barrier-disruptive mechanical and chemical stimuli (thrombin, pathologic CS). In addition, these PPG investigator have described the critical involvement of small GTPases Rac and Rho in remodeling of EC cytoskeleton and cell contacts essential for EC barrier regulation. Our published results and preliminary data strongly suggest that magnitude-dependent modulation of Rac and Rho activities by CS significantly impacts agonist-induced EC permeability changes. The Project #3 hypothesis is that pathologic CS and vascular endothelial growth factor (VEGF), known to be elevated during VILI, promote lung endothelial barrier dysfunction via synergistic effects on Rho pathway-mediated EC permeability. These processes are counterbalanced by Rac-dependent mechanisms induced by barrier-protective stimuli such as hepatocyte growth factor (HGF) and physiologic stretch. We speculate that focal adhesions may act as mechanosensors and modulate small GTPase activities via specific paxillin interactions with Rac and Rho protein regulators. Specific Aim #1 will study synergistic effects between pathologic CS and VEGF on activation of Rhomediated EC barrier dysfunction. Specific Aim #2 will define barrier-protective strategies in amelioration of VILI-associated EC barrier dysfunction via changes in a balance between the Rho and Rac activities. Specific Aim #3 will study novel mechanisms of Rac/Rho regulation by mechanochemical factors via interactions between wild type paxillin (or/and paxillin containing the Gly73Ser polymorphism) interactions with modulators of Rac and Rho activity (GIT2, betaPIX, PAK1 and p190RhoGAP). These studies will uncover novel molecular mechanisms involved in the pathogenesis and resolution of ventilator-induced lung injury.