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过抗癌治疗 是冠状动脉疾病（CAD）发展的主要危险因素之一。虽然 CAD 传统上 被视为一种大血管疾病，近期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结果有重大贡献。具有临床表现的受试者 CAD 的诊断表现出 NO 介导的微血管血流介导的扩张（FMD）同时消失 上调线粒体过氧化氢 (H2O2)，促进局部炎症和细胞增殖。 了解调节从 NO 到 H2O2 转换的贡献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 FMD 介质从 NO 改变为信号传导途径的几个组成部分。 双氧水。这些途径的共同特征是内皮线粒体 ROS 生成过多。 线粒体裂变和融合是 ROS 产生的已知调节因子，受到一组亲细胞的严格调节。 裂变和促融合蛋白表明这些因素可能决定 FMD 的介质 人体微血管系统，一个尚未探索的问题。本研究的目的是检验以下假设： 线粒体裂变/融合与人体微循环中 FMD 的介质密切相关。基于 初步数据我们预计裂变/融合的调节因子是线粒体 ROS 的基本介质 剪切力是否引起内皮细胞 NO 或 H2O2 释放的产生和决定因素。 线粒体和 ROS 也参与缺氧预处理 (HPC)，这是一种改善组织的刺激 对压力源的耐受性并预防疾病。人们对 HPC 和血管保护知之甚少 没有微循环方面的研究。我们的初步数据支持线粒体裂变和融合在 调解 HPC。我们将探讨 HPC 诱导血管保护的潜在机制。我们将学习 新鲜人冠状动脉和脂肪小动脉以及原代人微血管内皮细胞在体外使用 操纵裂变和融合介质并确定这些变化如何的药理学和遗传工具 有助于在 CAD 或急性应激后（血糖升高、 腔内压力）。我们将检验线粒体裂变与 H2O2 相关的过度假设 而线粒体融合促进生理性NO介导的扩张流动。 目标 1：裂变/聚变或其调节器的变化是必要且充分的，以解释 CAD 或血管应激（IILP 或 HG）期间 FMD 介质从 NO 转变为 H2O2 目标 2：研究低氧血管预处理是否改善的机制 急性应激（IILP、HG）后或患有 CAD 受试者的微血管功能涉及增加 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.