TRPV4 in Regulation of Lung Endothelial Permeability

我们认为急性肺损伤模式可能以独特的内皮损伤为特征。 基于它们针对的钙离子进入途径和这些通道的表达模式的“指纹” 蛋白质。瞬时受体潜能(Trp)蛋白的典型亚家族成员包括 钙离子通道亚单位参与肺钙离子内流依赖性调节 肺泡外血管内皮细胞通透性。我们观察到心力衰竭会导致心脏功能丧失 通透性对储藏耗尽的反应，但不对14，15-环氧二十碳三烯酸(14，15-EET)，一种脂质 这仅在肺泡间隔毛细血管内促进钙离子依赖性急性肺损伤，提示14，15- EET靶向于隔微血管中表达的一个不同的通道。我们的初步数据显示 新的候选基因--TrPV4--Trp蛋白香草型亚家族成员。我们假设 肺泡间隔内皮细胞表达TRPV4通道的调节整合钙通道依赖 渗透性对各种刺激的反应，包括热、EETs和高血管压力。此外，我们 间隔毛细血管内皮细胞TRPV4依赖性通透性反应独立的假设 因此，在慢性心力衰竭时应保留钙离子通道。目标1将 确定TRPV4是否是EET和机械扰动促进钙离子的共同靶点 肺泡间隔内皮细胞通透性增加所需的内流，以及 温度是否设置此响应的增益。目标2将揭示TRPV4介导的内皮细胞 在慢性心力衰竭模型中，间隔毛细血管的通透性反应被保留。 TRPC通道被下调。我们将通过以下具体措施来实现这些目标： 大鼠和小鼠离体肺的通透性和Ca~(2+)内流以及肺和血管腐蚀铸型的显微镜观察 为了绘制通透性反应的空间异质性，用药理学工具来操纵信号 与TRPV4和TRPV4-/-小鼠的门控有关的通路。这项工作将提供第一个严谨的 正常肺内皮细胞通透性调节相关的TRPV4通道表达分析 微血管系统。

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.