Signaling Mechanisms for Hypoxic Pulmonary Vasoconstriction

描述（由申请人提供）：肺血管收缩功能减退（HPV）是维持肺中局部肺泡通气和肺灌注充分匹配的重要生理过程，但也可能导致肺动脉高压。肺动脉平滑肌细胞（PASMCs）内[Ca 2 +]i升高是HPV发病的关键因素。[Ca 2 +]i的缺氧增加可能是由于肌浆网通过兰尼碱受体/Ca 2+释放通道（RyR）释放细胞内Ca 2+所致，RyR被来自线粒体和NADPH氧化酶（NOX）的活性氧（ROS）信号激活。NOX依赖性低氧ROS产生是线粒体ROS的继发性。然而，缺氧产生ROS信号的分子基础仍然不清楚。在这里，我们提出了一个创新的中心假设，线粒体复合物III中的rieske是一个关键的，初始的缺氧传感分子，它介导了缺氧ROS的产生（在复合物III，线粒体，然后胞质溶胶），RyR激活，[Ca 2 +]i增加和收缩的PASMCs，导致肺血管收缩和高血压。此外，Rieske表达可能会有所不同，以确定阻力和管道肺动脉以及体动脉SMC的缺氧反应的异质性。为了检验这一新的假设，我们将解决以下基本问题（具体目标）：（1）线粒体复合物III中的Rieske是介导低氧ROS产生、RyR活化的关键初始分子，PASMCs [Ca ~（2+）]i增加和收缩是Rieske介导的低氧ROS信号和伴随的RyR依赖性Ca ~（2+）信号在低氧性肺动脉高压中的重要作用。在肺动脉和体动脉平滑肌细胞中，Rieske的表达是否不同，以介导低氧ROS信号和RyR介导的信号的异质性？这些具体目标将在分子、复合体、线粒体、细胞、组织和生物体水平上使用互补的分子、生物化学、生理学和遗传学方法来实现。这一发现将加深我们对PASMCs缺氧性Ca ~（2+）和收缩反应机制以及肺动脉和体动脉平滑肌细胞缺氧反应异质性的理解。我们的数据也可能有助于确定肺动脉高压和其他相关肺部疾病的新治疗靶点。

DESCRIPTION (provided by applicant): Hypoxic pulmonary vasoconstriction (HPV) is an important physiological process that maintains the sufficient matching of regional alveolar ventilation and pulmonary perfusion in the lungs, but may also lead to pulmonary hypertension. An increase in [Ca2+]i in pulmonary artery smooth muscle cells (PASMCs) is a key factor in HPV. The hypoxic increase of [Ca2+]i may occur due to intracellular Ca2+ release from the sarcoplasmic reticulum via ryanodine receptors/Ca2+ release channels (RyRs), which are activated by reactive oxygen species (ROS) signaling from mitochondria and NADPH oxidase (NOX). NOX-dependent hypoxic ROS generation is secondary to mitochondrial ROS. However, the molecular basis by which hypoxia generates ROS signaling still remains unclear. Here, we propose an innovative central hypothesis that rieske in the mitochondrial complex III is a key, initial hypoxic sensing molecule, which mediates the hypoxic ROS generation (in the complex III, mitochondria and then cytosol), RyR activation, [Ca2+]i increase and contraction in PASMCs, leading to pulmonary vasoconstriction and hypertension. In addition, rieske expression may vary to determine the heterogeneity of hypoxic responses in resistance and conduit pulmonary as well as systemic artery SMCs. To test this novel hypothesis, we will address the following fundamental questions (Specific Aims): (1) is rieske in the mitochondrial complex III a key, initial molecule that mediates the hypoxic ROS production, RyR activation, [Ca2+]i increase and contraction in PASMCs~ (2) are rieske-mediated hypoxic ROS signaling and attendant RyR-dependent Ca2+ signaling important for hypoxic pulmonary hypertension~ and (3) does rieske vary in expression to mediate the heterogeneity of hypoxic ROS signaling, RyR-mediated signaling in pulmonary and systemic artery SMCs? These specific aims will be implemented using complementary molecular, biochemical, physiological, and genetic approaches at the molecular, complex, mitochondrial, cellular, tissue and organism levels. The findings will extend our understanding of the mechanisms for hypoxic Ca2+ and contractile responses in PASMCs and also the heterogeneity of hypoxic responses in pulmonary and systemic artery SMCs. Our data may also help to identify novel therapeutic targets for pulmonary hypertension and other related lung diseases.