Critical role of Mitochondrial Fission/Fusion in Regulation of Microvascular Endothelial Function

年龄增加、存在其他心血管风险因素或既往接受过抗癌治疗， 冠状动脉疾病（CAD）的主要危险因素之一。虽然CAD传统上 被认为是大血管疾病，最近大量数据表明， 对心血管疾病的病理生理学和结局有重大影响。具有临床 CAD的诊断表现出NO介导的微血管流动介导的扩张（FMD）的损失，同时 线粒体过氧化氢（H2 O2）的上调，促进局部炎症和细胞增殖。 了解调节从NO到H2 O2的转换的作用机制可能有助于减少 血管旁分泌氧化还原毒性的组织损伤风险。 我们已经确定了信号通路的几个组成部分，该通路将FMD的介质从NO改变为 过氧化氢这些途径中的每一个的共同特征是过量的内皮线粒体ROS生成。 线粒体的分裂和融合，已知的ROS产生的调节器，是由一组前- 分裂和pro-fusion蛋白表明，这些因素的可能性，决定调解FMD在 人类微血管系统，一个未被探索的问题。这项研究的目的是检验假设， 线粒体分裂/融合与人微循环中FMD的介体密切相关。基于 初步数据表明，我们预期裂变/融合调节因子是线粒体ROS的基本介质 剪切力是否促进内皮细胞NO或H2 O2的释放及其决定因素。 线粒体和ROS也参与低氧预适应（HPC），一种改善组织 对压力的耐受性和对疾病的保护。关于HPC和血管保护， 没有微循环研究。我们的初步数据支持线粒体分裂和融合在 中介HPC。HPC诱导的血管保护的潜在机制将被探索。我们将研究 新鲜的人冠状动脉和脂肪小动脉以及原代人微血管内皮细胞的体外培养， 药理学和遗传学工具来操纵裂变和融合介质，并确定这些变化是如何发生的。 有助于在CAD中或急性应激后观察到的FMD机制的改变（葡萄糖升高， 腔内压力）。我们将检验线粒体分裂与H2 O2相关的过度假设 而线粒体融合促进生理性NO介导的扩张以流动。 目的1：裂变/聚变或其调节剂的变化是必要的，足以解释 CAD或血管应激（IILP或HG）期间FMD介质从NO向H2 O2的转变 目的2：探讨低氧血管预适应改善缺血再灌注损伤的机制 急性应激后（IILP，HG）或CAD受试者的微血管功能涉及 线粒体融合

Increased age, presence of other cardiovascular risk factors or previous treatment with anti-cancer therapy are among the leading risk factors for development of coronary artery disease (CAD). While CAD is traditionally viewed as a large vessel disease substantial recent data indicate that impaired microvascular function contributes substantially to pathophysiology and outcomes in cardiovascular disease. Subjects with a clinical diagnosis of CAD exhibit loss of NO-mediated microvascular flow-mediated dilation (FMD) concurrent with upregulation of mitochondrial hydrogen peroxide (H2O2), promoting local inflammation and cellular proliferation. Understanding the contributing mechanisms that regulate the switch from NO to H2O2 may help to reduce the risk of tissue injury from vascular paracrine redox toxicity. We have identified several components of the signaling pathway that changes the mediator of FMD from NO to H2O2. The common feature of each of these pathways is excess endothelial mitochondrial ROS generation. Mitochondrial fission and fusion, known regulators of ROS production, are tightly regulated by a group of pro- fission and pro-fusion proteins suggesting the possibility that these factors determine the mediator of FMD in the human microvasculature, an unexplored question. The goal of this study is to test the hypothesis that mitochondrial fission/fusion is critically linked to the mediator of FMD in the human microcirculation. Based on preliminary data we expect that regulators of fission/fusion are fundamental mediators of mitochondrial ROS production and determinants of whether shear elicits release of endothelial NO or H2O2. Mitochondria and ROS are also involved in hypoxic preconditioning (HPC), a stimulus that improves tissue tolerance to stressors and protects against disease. Very little is known about HPC and vascular protection with no studies in the microcirculation. Our preliminary data support a role for mitochondrial fission and fusion in mediating HPC. This potential mechanism for HPC induced vascular protection will be explored. We will study fresh human coronary and adipose arterioles and primary human microvascular endothelial cells in vitro using pharmacological and genetic tools to manipulate fission and fusion mediators and determine how these changes contribute to alterations in mechanisms of FMD observed in CAD or after acute stress (elevated glucose, intraluminal pressure). We will test the overreaching hypothesis that mitochondrial fission is associated with H2O2 while mitochondrial fusion promotes physiological NO mediated dilation to flow. Aim 1: Changes in fission/fusion or its regulators are necessary and sufficient to explain the transition in the mediator of FMD from NO to H2O2 during CAD or vascular stress (IILP or HG) Aim 2: Investigate whether the mechanism by which hypoxic vascular preconditioning improves microvascular function after acute stress (IILP, HG) or in subjects with CAD involves an increase in mitochondrial fusion.