Pivotal Role of Mitochondrial Telomerase in Regulation of Vascular Tone and Redox Homeostasis

项目摘要 端粒酶是一种核糖核蛋白，它可以抵消端粒的缩短， 研究小组在减弱线粒体活性氧形成方面具有非典型作用 图2显示了来自患有冠状动脉疾病（CAD）的受试者的冠状小动脉中的线粒体活性氧（mtROS）。我们证明了 TERT的激活可以逆转血流诱导的内皮依赖性舒张机制，从H2 O2-到 否，将表型恢复为在无CAD的受试者中观察到的表型。在本提案中，我们旨在调查 线粒体特异性端粒酶活性的作用及是否为显性负剪接变异 β del TERT在扩张器机制的这种表型变化中至关重要。我们的核心假设是线粒体 DNA损伤是导致ROS产生增加的根本原因之一。已知mtROS 促进小动脉硬化和内皮功能障碍的发展，使个体易患血管性疾病 并发症NO对线粒体ROS的产生具有众所周知的抑制作用，并且也已被证明 增加端粒酶。核或线粒体端粒酶活性是否有助于心血管疾病 保护没有定义。我们开发了新的核（nucTERT）或线粒体（mitoTERTi）抑制剂， 端粒酶活性，以区分核端粒酶和线粒体端粒酶在介导血管生成中的作用。 保护性表型我们将从细胞周期的变化来确定线粒体端粒酶在这种机制变化中的作用。 健康（NO介导）到疾病（H2 O2介导）在小鼠和人的阻力血管。 我们假设线粒体端粒酶通过防止线粒体DNA损伤在细胞凋亡中起保护作用。 正常情况下，而疾病中β del TERT的表达抑制了这种保护作用，并提高了 血管细胞的氧化应激，并诱导NO转化为H2 O2作为介导的FMD。这将 通过解决两个具体目标进行测试。 首先，我们将确定线粒体定位的端粒酶是否是必要的和足够的维持， NO而不是mtH 2 O2作为介质的流动诱导的扩张在人体微循环。二是 研究CAD是否能促使NO转换为H2 O2作为FMD的介导剂， 损害线粒体功能涉及β-del TERT的积累。我们将使用现有的药理学和 基因工具，将导致在疾病中恢复微血管功能的策略。这个新的假设 具有重要的转化潜力，确定了新的治疗靶点，以减轻病理变化 与微血管疾病有关。

Project Abstract Telomerase a ribo-nucleoprotein that counteracts telomere shortening has recently been shown by our investigative team to have a non-canonical role in attenuating formation of mitochondrial reactive oxygen species (mtROS) in coronary arterioles from subjects with coronary artery disease (CAD). We demonstrated that activation of TERT can reverse the mechanism of flow-induced endothelium-dependent dilation from H2O2- to NO, restoring the phenotype to one observed in subjects without CAD. In this proposal, we aim to investigate the role of mitochondrial specific effects of telomerase activity and whether the dominant negative splice variant β del TERT is critical in this phenotypic change in dilator mechanism. Our central hypothesis is that mitochondrial DNA damage is one of the underlying causes that leads to increase in ROS production. mtROS is known to promote development of arteriolosclerosis and endothelial dysfunction predisposing individuals to vascular complications. NO has a well-known inhibitory effect on mtROS generation and has also been demonstrated to increase telomerase. Whether nuclear or mitochondrial telomerase activity contributes to cardiovascular protection is not defined. We developed novel inhibitors of nuclear (nucTERT) or mitochondrial (mitoTERTi) telomerase activity to differentiate the roles of nuclear and mitochondrial telomerase in mediating vascular protective phenotypes. We will identify the role of mitochondrial telomerase in this change of mechanism from health (NO mediation) to disease (H2O2 mediation) in mouse and human resistance vessels. We hypothesize that mitochondrial telomerase plays a protective role by preventing mtDNA damage in normal conditions, while expression of β del TERT in disease suppresses this protective effect and elevates vascular cellular oxidative stress, and induces the conversion from NO to H2O2 as the mediator of FMD. This will be tested by addressing two specific aims. First, we will determine whether mitochondrial localization of TERT is necessary and sufficient to maintain NO rather than mtH2O2 as the mediator of flow-induced dilation in the human microcirculation. Second, we will investigate whether the mechanism by which CAD elicits a switch from NO to H2O2 as the mediator of FMD and impairs mitochondrial function involves accumulation of β-del TERT. We will use existing pharmacological and genetic tools that will lead to strategies for restoration of microvascular function in disease. This novel hypothesis has important translational potential, identifying new therapeutic targets for moderating the pathological changes associated with microvascular disease.