Linking cell death and mitochondrial quality control mechanisms in heart disease

将心脏病中的细胞死亡和线粒体质量控制机制联系起来

• 批准号: 9032529
• 负责人: Gerald W. Dorn
• 金额: $ 51.5万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE, INC
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2019-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9032529
• 关键词: Acute; Adult; Animals; Apoptosis; Binding; Biogenesis; Biology; Blood Circulation; Cardiac; Cardiac Myocytes; Cell Death; Cells; Cessation of life; Collaborations; Complex; Data; Disease; Figs - dietary; Heart; Heart Diseases; Heart failure; In Vitro; Individual; Infarction; Injury; Ischemia; Lead; Link; Literature; Mediating; Mediator of activation protein; Mitochondria; Modeling; Molecular; Molecular Conformation; Necrosis; Pathogenesis; Physiological; Postdoctoral Fellow; Process; Production; Quality Control; Reperfusion Therapy; Research; Research Assistant; Role; Signal Transduction; Structure; System; Testing; Work; base; experience; genetic manipulation; heart cell; in vivo; innovation; mortality; parkin gene/protein; prevent; professor; public health relevance; research study

 DESCRIPTION (provided by applicant): Mitochondria engage in multiple fundamental processes including biogenesis, fission/fusion, mitophagy, and cell death - in addition to their role as ATP generators in the cell. These processes are complex, and for this reason, have been largely studied in isolation. Yet, it is clear that they overlap substantially at the molecula level, functionally, and with respect to their roles in disease. In this application, we propose experiments that bi-directionally connect Bax, a central mediator of cardiomyocyte death, with Parkin, an important activator of mitophagy in cardiomyocytes. Using genetic manipulations, we have found unexpectedly that endogenous levels of Bax in healthy cells suppress mitophagy. We have observed this in adult cardiomyocytes in vitro and in the heart in vivo. We postulate that this is a physiological mechanism that restrains inappropriate or excessive elimination of mitochondria, a situation that would be deleterious to cardiomyocytes, which are highly dependent on ATP. We will elucidate the mechanism, which may involve an interaction between Bax and Parkin, and test the functional significance in vitro and in vivo. The fact that Bax and Parkin interact raises the reciprocal question: What might Parkin be doing to Bax in the heart? Previous work in non-cardiac systems has shown that Parkin inhibits Bax translocation to mitochondria during cell death, but the mechanism has not been elucidated. Parkin is known to inhibit cardiomyocyte death in vitro, and deletion of Parkin in vivo markedly exacerbates post-infarct remodeling, heart failure, and mortality. These effects have been assumed to be mediated solely through Parkin-stimulated mitophagy. Given the directness of the connection between Bax and cardiomyocyte apoptosis and necrosis, however, we challenge that view and hypothesize that Parkin protects the heart primarily through its inhibition of Bax. We will test ths hypothesis and delineate the molecular mechanism by which Parkin inhibits Bax. Accordingly, the over-arching hypothesis of this project is that Bax and Parkin antagonize each other for the benefit of cardiomyocytes: The binding of Bax, likely in its cell death-inactive conformation, to Parkin inhibits Parkin-mediated mitophagy to prevent mitochondrial depletion. Conversely, the Bax-Parkin interaction inhibits Bax, likely through interfering with its transition to its active conformation, thereby inhibiting cardiomyocyte apoptosis and necrosis. This is an MPI application that brings together the expertise of Richard Kitsis (cardiomyocyte death) and Gerald Dorn (cardiac mitophagy). This research is highly significant as it will stimulate the field to consider and investigate connections between individual mitochondrial processes, such as cell death and mitophagy. In addition, it will lead to a reconsideration of the primary mechanism by which Parkin protects the heart. The work is also highly innovative because most of the concepts and relationships have not been previously considered. Through this research, we will achieve a better understanding of the pathogenesis of acute cardiac injury during ischemia/reperfusion and post-infarct remodeling.

 描述（由申请人提供）：线粒体除了在细胞中充当 ATP 发生器的作用外，还参与多种基本过程，包括生物发生、裂变/融合、线粒体自噬和细胞死亡。这些过程很复杂，因此，人们对这些过程进行了大量的孤立研究。然而，很明显，它们在分子水平、功能以及在疾病中的作用方面有很大的重叠。在此应用中，我们提出了将心肌细胞死亡的中心介质 Bax 与心肌细胞线粒体自噬的重要激活剂 Parkin 双向连接的实验。通过基因操作，我们意外地发现健康细胞中的内源性 Bax 水平会抑制线粒体自噬。我们在体外的成人心肌细胞和体内的心脏中观察到了这一点。我们假设这是一种抑制线粒体不适当或过度消除的生理机制，这种情况对高度依赖 ATP 的心肌细胞有害。我们将阐明其机制，可能涉及 Bax 和 Parkin 之间的相互作用，并在体外和体内测试其功能意义。 Bax 和 Parkin 相互作用的事实提出了一个相互的问题：Parkin 可能会对 Bax 的内心做什么？此前在非心脏系统中的研究表明，Parkin 在细胞死亡过程中抑制 Bax 易位至线粒体，但其机制尚未阐明。已知 Parkin 在体外可抑制心肌细胞死亡，而在体内缺失 Parkin 会显着加剧梗塞后重塑、心力衰竭和死亡率。这些效应被认为是仅通过帕金刺激的线粒体自噬介导的。然而，鉴于 Bax 与心肌细胞凋亡和坏死之间的直接联系，我们对这一观点提出质疑，并假设 Parkin 主要通过抑制 Bax 来保护心脏。我们将检验这个假设并描述 Parkin 抑制 Bax 的分子机制。因此，该项目的总体假设是，Bax 和 Parkin 为了心肌细胞的利益而相互拮抗：Bax（可能处于细胞死亡非活性构象）与 Parkin 的结合会抑制 Parkin 介导的线粒体自噬，从而防止线粒体耗竭。相反，Bax-Parkin 相互作用可能通过干扰 Bax 向活性构象的转变来抑制 Bax，从而抑制心肌细胞凋亡和坏死。这是一个 MPI 应用程序，汇集了 Richard Kitsis（心肌细胞死亡）和 Gerald Dorn（心脏线粒体自噬）的专业知识。这项研究非常重要，因为它将刺激该领域 考虑和研究个体线粒体过程之间的联系，例如细胞死亡和线粒体自噬。此外，它将导致人们重新考虑帕金保护心脏的主要机制。这项工作也具有高度创新性，因为大多数概念和关系以前都没有被考虑过。通过这项研究，我们将更好地了解缺血/再灌注和梗塞后重塑过程中急性心脏损伤的发病机制。