Signaling Mechanisms for Hypoxic Pulmonary Vasoconstriction

描述（申请人提供）：缺氧肺血管收缩（Hypoxic pulmonary vasocontraction， HPV）是维持肺内局部肺泡通气与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）中[Ca2+]i的增加是HPV的关键因素。[Ca2+]i的缺氧增加可能是由于细胞内Ca2+通过ryanodine受体/Ca2+释放通道（RyRs）从肌浆网释放，这些通道被线粒体和NADPH氧化酶（NOX）的活性氧（ROS）信号激活。一氧化氮依赖性缺氧ROS的产生继发于线粒体ROS。然而，缺氧产生ROS信号的分子基础仍不清楚。在这里，我们提出了一个创新的中心假设，即线粒体复合体III中的rieske是一个关键的，初始的缺氧感知分子，它介导缺氧ROS的产生（在复合体III中，线粒体然后是细胞质），RyR激活，PASMCs中[Ca2+]i的增加和收缩，导致肺血管收缩和高血压。此外，rieske的表达可能会发生变化，以确定抵抗性和导管肺以及全身动脉SMCs中缺氧反应的异质性。为了验证这一新颖的假设，我们将解决以下基本问题（具体目标）：(1) rieske在线粒体复合体III中是一个关键的初始分子，介导缺氧ROS的产生，RyR激活，PASMCs中[Ca2+]i的增加和收缩~ (2)rieske介导的缺氧ROS信号和伴随的RyR依赖的Ca2+信号在缺氧肺动脉高压中是否重要~ (3)rieske是否通过表达变化来介导缺氧ROS信号和RyR介导的信号在肺和全身动脉SMCs中的异质性？这些具体目标将在分子、复杂、线粒体、细胞、组织和有机体水平上使用互补的分子、生化、生理和遗传方法来实现。这些发现将扩展我们对PASMCs中缺氧Ca2+和收缩反应机制的理解，以及肺动脉和全身动脉SMCs中缺氧反应的异质性。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.