Mitochondrial ATP Synthase in Cardiac Biology and Disease

线粒体 ATP 合酶在心脏生物学和疾病中的作用

• 批准号: 10632143
• 负责人: Richard N Kitsis
• 金额: $ 73.14万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10632143
• 关键词: ATP Synthesis Pathway; Adenine Nucleotide Translocase; Age; Apoptosis; Attenuated; Biology; Cardiac; Cardiac Myocytes; Cell Death; Cessation of life; Collaborations; Complex; Cytoplasm; Data; Depressed mood; Disease; Electron Transport; Engineering; Event; Exhibits; Functional disorder; Gene Deletion; Genetic; Heart; Heart failure; Human; Individual; Infarction; Investigation; Knockout Mice; Left; Mammalian Cell; Mediating; Metabolic; Mitochondria; Mitochondrial Proton-Translocating ATPases; Modeling; Mus; Myocardial Ischemia; Myocardial dysfunction; Necrosis; Pathway interactions; Patients; Pharmaceutical Preparations; Protein Complex Subunit; Radioisotopes; Regulation; Reperfusion Therapy; Role; Specimen; Surgeon; Testing; Uncertainty; Ventricular; Wild Type Mouse; defined contribution; experimental study; gain of function; heart function; in vivo; inhibitor; loss of function; mitochondrial permeability transition pore; mortality; mouse model; novel; pressure; response

The mitochondrial ATP synthase is a multi-subunit complex that catalyzes the synthesis of >90% of ATP in mammalian cells. The ATP synthase is also hypothesized to function as the mitochondrial permeability transition pore (mPTP), a major trigger for necrotic cell death. Except for short-term drug inhibitor experiments, the functions of the ATP synthase have never been assessed in the heart in vivo. We have created the first mouse models deficient in the entire ATP synthase complex in cardiomyocytes. To accomplish this, we individually deleted at 5 weeks of age ATP5L and ATP5J, ATP synthase subunits required for complex assembly. Thus far, we have analyzed the ATP5L KO mice. Because the half-lives of most mitochondrial ATP synthase subunits exceed 35 days in cardiomyocytes, the abundance of the complex decreased gradually with 15% remaining at 12 weeks post-deletion. KO mice uniformly developed heart failure (HF) with reduced systolic function and died between 12-16 weeks post-deletion. Analysis of cardiac mitochondria confirmed reduced ATP synthesis rates as expected. Unexpectedly, however, ATP concentrations in whole heart lysates, as well as in cytoplasmic and mitochondrial fractions, were elevated in KO, compared with control, mice. Parallel investigations into the role of the ATP synthase as the mPTP revealed that, rather than inhibiting Ca2+-induced mPTP opening, deficiency of the ATP synthase sensitized this event. Moreover, mice with cardiomyocyte-specific deficiency of the ATP synthase exhibited larger – not smaller – infarcts following myocardial ischemia/reperfusion in vivo. Finally, we observed that ATP synthase levels and activity in mitochondria decrease during pressure overload-induced HF in wild type mice. These results suggest: (a) Loss of the mitochondrial ATP synthase activates marked metabolic/energetic responses and unleashes previously unrecognized mechanisms that promote lethal HF. Regarding the latter, our preliminary studies implicate Complex II to I reverse electron transport (RET) promoting ROS-induced cardiomyocyte apoptosis. (b) Our studies cast doubt that the ATP synthase also functions as the mPTP and rather suggest that it is a negative regulator. (c) Deficient ATP synthase function may contribute to acquired forms of HF. We propose studies to understand the mechanistic basis of our observations and to assess the role deficient mitochondrial ATP synthase function in human HF. Aim 1. To define metabolic/energetic pathways that are activated and mechanisms that contribute to HF in mice with cardiomyocyte-specific deficiency of the mitochondrial ATP synthase. Aim 2. To test definitively whether the mitochondrial ATP synthase is the mPTP. Aim 3. To assess the role of deficient mitochondrial ATP synthase abundance/function in pressure overload-induced HF in mice and in human HF. These studies break new ground in investigating functions of the mitochondrial ATP synthase in cardiomyocytes in vivo. Deliverables include the assessment of RET as a novel HF mechanism, a definitive determination of the role of the ATP synthase as the mPTP, and a delineation of the role deficient ATP synthase function in human HF.

线粒体ATP合酶是一种多生成复合物，可催化> 90％的ATP的合成 哺乳动物细胞。还假设ATP合酶作为线粒体通透性过渡起作用 孔（MPTP），是坏死细胞死亡的主要触发因素。除短期药物抑制剂实验外， ATP合酶的功能从未在体内心脏中进行评估。我们创建了第一个鼠标 心肌细胞中整个ATP合酶复合物缺乏的模型。为此，我们单独 在5周龄ATP5L和ATP5J时删除，复合组装需要的ATP合酶亚基。那远， 我们已经分析了ATP5L KO小鼠。因为大多数线粒体ATP合酶亚基的半衰期 在心肌细胞中超过35天，复合物的抽象逐渐降低，剩下15％ 消失后12周。 KO小鼠均匀发展为收缩功能降低并死亡的心力衰竭（HF） 损耗后12-16周之间。心脏线粒体的分析证实ATP合成率降低 正如预期的。然而，出乎意料的是，整个心脏裂解物以及细胞质中的ATP浓度和 与对照小鼠相比，KO中的线粒体级分升高。平行调查 作为MPTP的ATP合酶表明，而不是抑制Ca2+诱导的MPTP开放，而是缺乏 ATP合酶对此事件敏感。此外，患有心肌细胞特异性缺陷的小鼠ATP 在体内心肌缺血/再灌注后，合成酶暴露于更大的（不是较小）的梗死。最后，我们 观察到在压力超负荷引起的HF期间，ATP合酶水平和线粒体的活性降低 在野生型小鼠中。这些结果表明：（a）线粒体ATP合酶的损失激活了标记的 代谢/能量反应和释放先前未识别的机制，这些机制促进了致命的HF。 关于后者，我们的初步研究将复合物II与I反向电子传输（RET）促进有关 ROS诱导的心肌细胞凋亡。 （b）我们的研究表明，ATP合酶也起着 MPTP，而是暗示它是一个负调节器。 （c）缺乏ATP合酶功能可能有助于 获得的HF形式。我们建议研究了解我们的观察的机理基础并评估 人HF中的角色定义线粒体ATP合酶功能。目标1。定义代谢/能量 激活的途径和具有心肌细胞特异性缺乏的小鼠的HF的机制 线粒体ATP合酶的。目标2。确定测试线粒体ATP合酶是否是 MPTP。目标3。评估不足的线粒体ATP合酶抽象/功能在压力中的作用 小鼠和人类HF中的过载诱导的HF。这些研究在调查了 体内心肌细胞中的线粒体ATP合酶。可交付成果包括对RET的评估 新型的HF机制，确定对ATP合酶作为MPTP的作用的确定性和描述 人类HF中的作用定义ATP合酶功能。