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

基本信息

批准号：
10812556
负责人：
Richard N Kitsis
金额：
$ 3.57万
依托单位：
ALBERT EINSTEIN COLLEGE OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-06-01 至 2023-10-15
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10812556
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

项目摘要

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 合酶是一种多亚基复合物，可催化体内 90% 以上 ATP 的合成哺乳动物细胞中的 ATP 合酶也被开发为具有线粒体通透性转换的功能。孔（mPTP），坏死细胞死亡的主要触发因素除了短期药物抑制剂实验外。 ATP合酶的功能从未在体内进行过评估我们已经创造了第一只小鼠。为了实现这一目标，我们单独构建了心肌细胞中整个 ATP 合酶复合物缺陷的模型。 5 周龄时缺失 ATP5L 和 ATP5J，这是复杂组装所需的 ATP 合酶亚基。我们分析了 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，复合物的丰度逐渐下降，仅剩15% 删除后 12 周，KO 小鼠均出现心力衰竭 (HF)，收缩功能降低并死亡。删除后 12-16 周，心脏线粒体分析证实 ATP 合成率降低。然而，出乎意料的是，整个心脏裂解物以及细胞质和细胞中的 ATP 浓度。与对照小鼠相比，KO 小鼠的线粒体分数升高。 ATP合酶作为mPTP表明，缺乏Ca2+诱导的mPTP开放，而不是抑制Ca2+诱导的mPTP开放。此外，心肌细胞特异性缺乏 ATP 的小鼠也对这一事件敏感。体内心肌缺血/再灌注后，合酶出现更大而不是更小的梗塞。观察到压力过载引起的心力衰竭期间线粒体中的 ATP 合酶水平和活性降低在野生型小鼠中，这些结果表明：(a) 线粒体 ATP 合酶的丧失会显着激活。代谢/能量反应并释放以前未被识别的促进致命心力衰竭的机制。关于后者，我们的初步研究表明复合物 II 到 I 的反向电子传递 (RET) 促进 ROS 诱导的心肌细胞凋亡 (b) 我们的研究对 ATP 合酶也发挥着细胞凋亡的作用提出了怀疑。 mPTP 更确切地说表明它是一种负调节因子 (c) ATP 合酶功能缺陷可能导致。我们提出研究来了解我们观察到的机制基础并进行评估。线粒体 ATP 合酶功能缺陷在人类心衰中的作用目标 1. 定义代谢/能量。心肌细胞特异性缺陷小鼠中被激活的途径和导致心力衰竭的机制目标 2. 确定线粒体 ATP 合酶是否是线粒体 ATP 合酶。 mPTP。目标 3. 评估线粒体 ATP 合酶丰度/功能缺陷在压力中的作用这些研究在小鼠和人类心力衰竭的功能研究方面开辟了新的领域。体内心肌细胞线粒体 ATP 合酶的可交付成果包括对 RET 进行评估。新颖的 HF 机制，明确确定 ATP 合酶作为 mPTP 的作用，并描述 ATP合酶功能缺陷在人类心力衰竭中的作用。