Hepatocyte Growth Factor/c-Met Invovement in Lung EC Barrier Regulation

血管通透性的改变是包括动脉硬化在内的各种过程的一个明显特征， 炎症、急性肺损伤(ALI)和血管生成。相比之下，很少有人知道有这样的过程 确定水肿剂后的屏障保护或屏障修复。我们之前已经表明， 肝细胞生长因子(HGF)与其细胞表面受体酪氨酸激酶c-Met结合，促进 EC通过细胞骨架重排发挥屏障作用，减轻炎症性肺水肿的形成。 我们的数据表明，HGF促进c-Met重新聚集到专门的小窝蛋白-1富集型血浆中 膜微域称为脂筏，反式激活鞘氨醇1-磷酸受体(S1P1) 和CD44(一种主要的透明质酸糖蛋白受体)位于这些脂筏结构中。我们已经确定了 HGF/c-Met诱导的肌动蛋白细胞骨架重排和随后的EC的几种潜在调节因子 脂筏的屏障增强包括rac1交换因子，囊泡调节蛋白Tiaml， 动力蛋白2、肌球蛋白轻链激酶(MLCK)和帕西林。此外，编码c-蛋氨酸和帕西林的基因 含有编码单核苷酸多态(SNPs)，可能改变功能并导致增加 对ALI易感性。具体目标1将确定这些SNP在脂质中HGF/c-Met信号转导中的作用 木筏进入肌动蛋白细胞骨架，进而调节人体内皮细胞屏障。我们在小鼠身上的初步数据 脂多糖诱导的肺血管高通透性模型提示小窝蛋白-1 在体内调节HGF介导的血管完整性。具体目标#2将定义HGF/c-Met/小窝蛋白-1 调节内皮皮质肌动蛋白形成、张力和肺通透性的相互作用。此外， 我们发表的数据表明，HGF/c-Met的反式激活S1P1对其EC屏障的增强至关重要 属性。因此，为了探讨生长因子反式激活在调节EC屏障功能中的作用， 特定目标#3将确定HGF/c-Met/S1P1在调节内皮皮质肌动蛋白中的相互作用 形成、张力和肺通透性。具体目标#4将定义HGF/c-Met/CD44相互作用 调节内皮细胞皮质肌动蛋白的形成、张力和肺通透性。加深了对 HGF/c-Met介导的信号转导和脂筏EC屏障调节可能提供新的 治疗涉及EC屏障调节缺陷的各种疾病过程。

An alteration in vascular permeability is a defining feature of diverse processes including arteriosclerosis, inflammation, acute lung injury (ALI) and angiogenesis. In contrast, there is little known about processes that determine barrier protection or barrier restoration after edemagenic agents. We have previously shown that hepatocyte growth factor (HGF) binding to its cell surface receptor tyrosine kinase, c-Met, promotes increased EC barrier function via cytoskeletal rearrangement and attenuates inflammatory lung edema formation. Our data indicate that HGF promotes c-Met recruitment into specialized caveolin-1-enriched plasma membrane microdomains known as lipid rafts and transactivates sphingosine 1-phosphate receptor (S1P1) and CD44 (a major hyaluronan glycoprotein receptor) within these lipid raft structures. We have identified several potential regulators of HGF/c-Met-induced actin cytoskeletal rearrangement and consequent EC barrier enhancement in lipid rafts including the Rac1 exchange factor, Tiaml, the vesicle regulatory protein, dynamin 2, myosin light chain kinase (MLCK) and paxillin. Further, genes encoding c-Met and paxillin contain coding single nucleotide polymorphisms (SNPs) which potentially alter function and lead to increased susceptibility to ALI. Specific Aim #1 will identify the role of these SNPs in HGF/c-Met signaling from lipid rafts to the actin cytoskeleton and consequent human EC barrier regulation. Our preliminary data in murine model of lipopolysaccharide (LPS)-induced pulmonary vascular hyper-permeability suggests that caveolin-1 regulates HGF-mediated vascular integrity in vivo. Specific Aim #2 will define HGF/c-Met/caveolin-1 interactions in the regulation of endothelial cortical actin formation, tension and lung permeability. Further, our published data indicates that HGF/c-Met transactivation of the S1P1 is crucial for its EC barrierenhancing properties. Thus, to explore growth factor transactivation in regulating EC barrier function, Specific Aim #3 will identify HGF/c-Met/S1P1 interactions in the regulation of endothelial cortical actin formation, tension and lung permeability. Specific Aim #4 will define HGF/c-Met/CD44 interactions in the regulation of endothelial cortical actin formation, tension and lung permeability. Increased understanding of HGF/c-Met-mediated signal transduction and EC barrier regulation from lipid rafts may provide novel therapies for a variety of disease processes involving defects in EC barrier regulation.