桩蛋白对肺泡毛细血管内皮细胞通透性双向调节的分子机制

Acute Lung Injury (ALI), and its serious state Acute Respiratory Distress Syndrome (ARDS)， is a clinical syndrome characteristic of extensive lung capillary hyper-permeability. Although there has been a great development in the mechanism studies and clinical treaments, the mortality of this disease is still unacceptablly high at 50-70%. Paxillin is a scafold protein associated with many cytoskeltal proteins and signal molecules, and plays critical role in the formation of focal adhesion. Our current studies show that paxillin regulates endothelial permeability bi-directionally via small GTPase Rho and Rac, which function as molecular switch.We hypothesize that paxillin exerts bi-directional regulation of endothelial permeability by recruiting distinct signaling molecues through different tyrosine, serin and/or thryonin sites phosphorylation, whereas activateing or inhibiting GTPase activating protein (GAP) and guarnine exchange factor (GEF), leading to inhibition and activation of Rho and Rac, respectively. In this study we sought to apply in vitro and in vivo hyper-permeability models, use biochemistry, molecular biology, cellular biology and state or art live cell imaging methods to delineate the molecular mechanisms underlying the regulation of endothelial permeability by paxillin, and to provide theorial fundation for clinical therapy.

急性肺损伤及其严重阶段，急性呼吸窘迫综合症是以广泛的肺泡毛细血管通透性增加为主要表现的临床综合症。虽然近20多年来随着对其发病机理认识的增加及呼吸支持治疗的发展，但该病的死亡率仍然高达50-70%。 桩蛋白是一种与多种细胞骨架蛋白和信号分子相互作用的衔接蛋白和支架蛋白，在细胞粘着斑形成中发挥重要作用。我们目前的研究发现，桩蛋白可以双向调节内皮细胞的通透性，这种双向调节可能通过调节起着分子开关作用的小分子GTP酶Rho和Rac来实现。我们认为桩蛋白通过不同位点的磷酸化和去磷酸化， 与不同信号分子结合，激活或抑制调节Rho和Rac的GTPase激活蛋白和腺苷交换蛋白，来调控Rho和Rac的活性，从而实现内皮细胞通透性的双向调节。本研究拟通过体外、体内内皮细胞通透性模型，应用生物化学、分子生物学、细胞生物学等多种研究方法来阐明桩蛋白调节细胞通透性的分子机制，为临床治疗提供理论基础。