TRPV4 in Regulation of Lung Endothelial Permeability

我们认为急性肺损伤的典型特征可能是独特的内皮损伤 基于它们靶向的Ca 2+进入途径和这些通道的表达模式的“指纹” proteins.瞬时受体电位（TRP）蛋白的典型亚家族的成员包括 钙池操纵的钙通道亚基，参与肺钙通道依赖性调节 肺泡外血管的内皮通透性。我们观察到心力衰竭会导致 渗透性对储存耗竭的反应，但对脂质14，15-环氧二十碳三烯酸（14，15-EET）的反应不明显 仅在肺泡隔毛细血管中促进Ca 2+进入依赖性急性肺损伤，提示14，15- EET靶向中隔微血管中表达的独特通道。我们的初步数据显示 新的候选人-TRPV 4-TRP蛋白的香草素亚家族的成员。我们假设 在肺泡间隔内皮细胞中表达的TRPV 4通道的调节整合了Ca 2+进入依赖性的 渗透性对各种刺激的反应，包括热、Ehramidine和高血管压。我们还 假设隔毛细血管内皮中TRPV 4依赖性渗透性反应是独立的， 钙库操作的钙进入途径，因此应保留在慢性心力衰竭。AIM 1将 确定TRPV 4是否是Ehrs和机械扰动促进Ca 2+的共同靶点 肺肺泡隔室内皮通透性增加所需的内流，和 温度是否设置该响应的增益。AIM 2将揭示TRPV 4介导的内皮细胞 在慢性心力衰竭中，间隔毛细血管的渗透性反应得以保留，在该模型中， TRPC通道下调。我们将通过以下具体措施来实现这些目标： 离体大鼠和小鼠肺的通透性和Ca 2+内流，肺和血管腐蚀铸型的显微镜检查 绘制渗透性反应的空间异质性，操纵信号传导的药理学工具 涉及TRPV 4门控的途径和TRPV 4-/-小鼠。这项工作将提供第一个严格的 与完整肺中内皮通透性调节相关的TRPV 4通道表达的分析 微脉管系统

We propose that acute lung injury paradigms are likely to be characterized by unique endothelial injury "fingerprints" based on the Ca2+ entry pathways they target and the expression pattern of these channel proteins. Members of the canonical subfamily of transient receptor potential (TRP) proteins comprise subunits of store-operated Ca2+ channels and participate in Ca2+ entry-dependent regulation of lung endothelial permeability in extra-alveolar vessels. Our observation that heart failure leads to loss of the permeability response to store depletion but not that to 14,15-epoxyeicosatrienoic acid (14,15-EET), a lipid that promotes Ca2+ entry-dependent acute lung injury only in alveolar septal capillaries, suggests that 14,15- EET targets a distinct channel expressed in the septal microvasculature. Our preliminary data suggests a novel candidate - TRPV4 - a member of the vanilloid subfamily of TRP proteins. We HYPOTHESIZE that regulation of TRPV4 channels expressed in alveolar septal endothelium integrates the Ca2+ entry-dependent permeability response to diverse stimuli, including heat, EETs, and high vascular pressure. Further, we hypothesize that TRPV4-dependent permeability responses in septal capillary endothelium are independent of store-operated Ca2+ entry pathways, and thus should be retained in chronic heart failure. AIM 1 will determine whether TRPV4 is a common target by which EETs and mechanical perturbation promote Ca2+ influx required for increased endothelial permeability in the alveolar septal compartment of the lung, and whether temperature sets the gain of this response. AIM 2 will reveal whether TRPV4-mediated endothelial permeability responses in septal capillaries are retained in chronic heart failure, a model in which storeoperated TRPC channels are down-regulated. We will address these aims using specific measures of permeability and Ca2+ entry in isolated rat and mouse lung, microscopy of lung and vascular corrosion casts to map spatial heterogeneity in the permeability response, pharmacological tools to manipulate signaling pathways implicated in gating of TRPV4, and TRPV4-/- mice. This work will provide the first rigorous analysis of TRPV4 channel expression linked to regulation of endothelial permeability in the intact lung microvasculature.