Cav-1.TRPV4 regulation of endothelial function in small pulmonary arteries

摘要 肺动脉高压（PAH）是一种肺血管疾病， 确诊后三年45%。PAH通常与内皮依赖性血管舒张功能丧失相关， 其长期以来被认为是PAH发展的主要贡献者。然而，底层 PAH患者内皮依赖性血管舒张功能丧失的机制尚不清楚，特别是在原发性PAH患者中。 来自控制肺动脉压的小肺动脉（PA）的内皮。我们最近展示了 内皮TRPV 4（瞬时受体电位香草酸4）通道是内皮细胞的关键调节因子， PA中的依赖性血管舒张。在本申请中，我们提供了新的初步数据，内皮TRPV 4 通道调节静息肺动脉压（PAP），并且在PAH中受损。此外，我们表明， 支架蛋白小窝蛋白-1为蛋白激酶C（PKC）依赖性调节 TRPV 4通道，一种在PAH中有缺陷的机制。有趣的是，两种不同的过氧亚硝酸根清除剂 恢复了PAH中内皮TRPV 4通道的活性，这表明过氧亚硝酸盐可能是PAH的关键因素。 TRPV 4通道功能障碍。此外，外源性过氧亚硝酸盐也损害小窝蛋白-1·PKC 调节内皮TRPV 4通道功能。因此，我们假设过氧亚硝酸盐诱导的 Caveolin-1·PKC对TRPV 4通道功能的调节受损，导致内皮细胞的损失， PAH中的依赖性血管舒张。在具体目标1中，我们将使用来自内皮特异性TRPV 4的PA， caveolin-1敲除小鼠和人肺以确定一种新的caveolin-1·PKC·TRPV 4血管舒张信号转导 控制PAP的内皮调节的复合物。在具体目标2中，我们将测试假设， 过氧亚硝酸盐水平破坏PAH中的caveolin-1·PKC·TRPV 4血管舒张信号复合物。我们还将确定 降低PAH中过氧亚硝酸盐水平是否以TRPV 4依赖性方式降低PAP。这些研究将 确定了小PA中内皮TRPV 4通道异常有助于PAH，并奠定了 为拯救内皮TRPV 4通道功能的新治疗策略奠定了基础。

Abstract Pulmonary arterial hypertension (PAH) is a disease of pulmonary vasculature with a high mortality rate of up to 45% three years after diagnosis. PAH is often associated with the loss of endothelium-dependent vasodilation, which has long been thought to be a major contributor to development of PAH. However, the underlying mechanisms for the loss of endothelium-dependent vasodilation in PAH remain unclear, particularly in the native endothelium from small pulmonary arteries (PAs) that control pulmonary arterial pressure. We recently showed that endothelial TRPV4 (transient receptor potential vanilloid 4) channels are key regulators of endothelium- dependent vasodilation in PAs. In this application, we provide novel preliminary data that endothelial TRPV4 channels regulate resting pulmonary arterial pressure (PAP), and are impaired in PAH. Moreover, we show that scaffolding protein caveolin-1 provides a signaling platform for protein kinase C (PKC)-dependent regulation of TRPV4 channels, a mechanism that is defective in PAH. Interestingly, two different peroxynitrite scavengers restored endothelial TRPV4 channel activity in PAH, suggesting that peroxynitrite may be a key contributor to dysfunction of TRPV4 channel function. Additionally, exogenous peroxynitrite also impaired caveolin-1·PKC regulation of endothelial TRPV4 channel function. We, therefore, hypothesize that peroxynitrite-induced impairment in caveolin-1·PKC regulation of TRPV4 channel function contributes to the loss of endothelium- dependent vasodilation in PAH. In Specific Aim 1, we will use PAs from endothelium-specific TRPV4 and caveolin-1 knockout mice and human lungs to define a novel caveolin-1·PKC·TRPV4 vasodilator signaling complex that controls endothelial regulation of PAP. In Specific Aim 2, we will test the hypothesis that elevated peroxynitrite levels disrupt caveolin-1·PKC·TRPV4 vasodilator signaling complex in PAH. We will also determine whether lowering peroxynitrite levels in PAH reduces PAP in a TRPV4-dependent manner. These studies will establish that abnormalities in endothelial TRPV4 channels in small PAs contribute to PAH, and lay the foundation for novel therapeutic strategies to rescue endothelial TRPV4 channel function.