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

年龄增加、存在其他心血管危险因素或既往接受抗癌治疗的情况 冠状动脉疾病(CAD)的主要危险因素之一。虽然CAD传统上是 被视为一种大血管疾病最近的大量数据表明，微血管功能受损 对心血管疾病的病理生理学和预后有很大的贡献。有临床症状的受试者 冠心病的诊断表现为同时伴有NO介导的微血管血流介导的扩张(FMD)的丧失 上调线粒体过氧化氢(H_2O_2)，促进局部炎症和细胞增殖。 了解调节NO向过氧化氢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造成组织损伤的风险。 我们已经确定了将口蹄疫介体从NO改变为FMD的信号通路的几个组成部分 过氧化氢。这些途径的共同特征是内皮细胞线粒体产生过量的ROS。 线粒体分裂和融合是已知的ROS产生的调节因素，受到一组亲核基因的严格调控。 裂变和前融合蛋白提示这些因素可能决定了口蹄疫的介体。 人类微血管系统，这是一个未被探索的问题。这项研究的目标是检验这一假设 线粒体的分裂/融合与人类微循环中口蹄疫的介体密切相关。基于 初步数据表明，分裂/融合调节因子是线粒体ROS的基本调节因子 剪切是否引起内皮NO或H_2O_2释放的产生和决定因素。 线粒体和ROS也参与了低氧预适应(HPC)，这是一种改善组织的刺激 对压力源的耐受性和对疾病的保护。对HPC和血管保护知之甚少 没有关于微循环的研究。我们的初步数据支持线粒体分裂和融合在 调解HPC。我们将探讨HPC诱导血管保护的可能机制。我们会研究 新鲜人冠状动脉、脂肪小动脉和原代人微血管内皮细胞的体外培养 用于操纵裂变和融合介体并确定这些变化的药理学和遗传学工具 导致冠心病患者或急性应激(血糖升高、 腔内压力)。我们将检验线粒体分裂与过氧化氢有关的过分假设。 线粒体融合促进生理性NO介导的扩张流动。 目标1：裂变/融合或其调节因子的变化是必要的，也是充分解释 冠心病或血管应激(IILP或HG)中FMD介体从NO到H_2O_2的转变 目的2：探讨低氧预适应改善血管功能的机制 急性应激(IILP，HG)或冠心病受试者的微血管功能增加 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.