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

血管渗透性的改变是包括动脉硬化， 炎症、急性肺损伤（ALI）和血管生成。相比之下，对以下过程知之甚少： 在使用水肿剂后确定屏障保护或屏障恢复。我们之前已经证明， 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， EC屏障功能通过细胞骨架重排和减弱炎性肺水肿的形成。 我们的数据表明，肝细胞生长因子促进c-Met募集到专门的小窝蛋白-1富集血浆 膜微区称为脂筏和反式激活鞘氨醇1-磷酸受体（S1 P1） 和CD 44（一种主要的透明质酸糖蛋白受体）。我们已经确定 HGF/c-Met诱导的肌动蛋白细胞骨架重排和随后EC的几种潜在调节剂 脂筏中的屏障增强，包括Rac 1交换因子，Tiaml，囊泡调节蛋白， 发动蛋白2、肌球蛋白轻链激酶（MLCK）和桩蛋白。此外，编码c-Met和桩蛋白的基因 含有编码单核苷酸多态性（SNP），可能改变功能并导致增加 对ALI的易感性。具体目标#1将确定这些SNP在来自脂质的HGF/c-Met信号传导中的作用， 筏的肌动蛋白细胞骨架和随之而来的人类EC屏障调节。我们在小鼠中的初步数据 脂多糖（LPS）诱导的肺血管高通透性模型表明，小窝蛋白-1 调节体内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 在调节内皮皮质肌动蛋白的形成，张力和肺通透性的相互作用。此外，本发明还 我们发表的数据表明，S1 P1的HGF/c-Met反式激活对于其EC屏障增强至关重要 特性.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， 具体目标#3将确定HGF/c-Met/S1 P1在内皮皮质肌动蛋白调节中的相互作用 形成、张力和肺渗透性。具体目标#4将定义HGF/c-Met/CD 44相互作用， 调节内皮皮层肌动蛋白的形成、张力和肺通透性。更加了解 HGF/c-Met介导的信号转导和脂筏对EC屏障的调节可能提供新的 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.