Reduction of cardiac injury by targeting damaged mitochondria during reperfusion

通过针对再灌注期间受损的线粒体来减少心脏损伤

• 批准号: 8795682
• 负责人: Edward J Lesnefsky
• 金额: --
• 依托单位: VA VETERANS ADMINISTRATION HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8795682
• 关键词: Acute myocardial infarction; Aging; Apoptosis; Apoptotic; Attenuated; Autophagocytosis; BCL2 gene; Biological Preservation; Bypass; Cardiac; Cardiac Myocytes; Cell Death; Cell Respiration; Clinical Research; Complex; Defect; Diabetes Mellitus; Electron Transport; Electron Transport Complex III; Electron Transport Pathway; Equilibrium; Exhibits; Genetic; Heart; Infarction; Injury; Intervention; Ischemia; Lead; Measures; Mediating; Mediator of activation protein; Membrane; Metabolism; Mitochondria; Morbidity - disease rate; Muscle Cells; Myocardial; Myocardial Infarction; Myocardium; NADH dehydrogenase (ubiquinone); Outer Mitochondrial Membrane; Oxidants; Pathway interactions; Peptides; Permeability; Phase; Population; Reperfusion Injury; Reperfusion Therapy; Role; Scheme; Signal Transduction; Site; Therapeutic; Therapeutic Intervention; Veterans; Work; cell injury; design; genetic approach; individualized medicine; inhibitor/antagonist; mitochondrial permeability transition pore; mortality; patient population; prevent; response; therapy design

DESCRIPTION (provided by applicant): Cardiac mitochondria (MITO) are critical mediators of myocardial injury during ischemia and reperfusion. During ischemia, MITO sustain damage that is mediated by the mitochondrial electron transport chain (ETC). Our previous work discovered two major mechanisms of ETC-driven injury to MITO during ischemia. First, the ETC itself is damaged at complex I and complex III. Second, the anti-apoptotic peptide bcl-2 is depleted from MITO. We found that when inhibitors were used to block the ETC during ischemia, this damage to MITO was prevented. More remarkably, when MITO were protected during ischemia, infarct size measured after REP was substantially reduced. As a result of the ETC-driven damage during ischemia, MITO become effectors of cardiomyocyte injury during reperfusion. We hypothesize that the two mechanisms of ETC-dependent ischemic damage dominate cardiac injury during reperfusion. At the onset of reperfusion, damaged MITO generates oxidative injury, undergo catastrophic permeability changes and activate cell death programs. The mechanisms leading to these injurious global responses are identified and will lead to strategies for therapeutic intervention during early and later periods of reperfusion. In preliminary work for this proposal, we found tha although the ETC has already sustained damage, intervention during reperfusion to directly manipulate mitochondrial function can decrease cardiac injury. We have focused on mechanism-driven approaches to directly modulate metabolism using pharmacologic and genetic modulation of mitochondrial function, including the use transient and partial blockade of complex I. The experimental approaches are designed to bypass upstream signaling cascades and instead directly interact with the ultimate target and effector of the cardiac injury, the MITO We propose that at the onset of reperfusion, resumption of oxidative metabolism by the damaged ETC with electron transport from complex I into complex III generates oxidants that lead to opening of the mitochondrial permeability transition pore and cell death. Aim 1 identifies and studies sites within complexes I and III that generate the injury at reperfusion. We hypothesize that the ETC-dependent depletion of bcl-2 from MITO during ischemia leads to mitochondrial outer membrane permeation and the activation of programmed cell death during reperfusion. Aim 2 studies the role of bcl-2 depletion in permeability transition-mediated cardiac injury during early reperfusion that may serve to reinforce complex I-driven activation. Myocytes protected by intervention during the initial phase of reperfusion remain susceptible to MITO- driven cell death during longer periods of reperfusion. We hypothesize that the persistence of MITO with ischemia-damaged ETC and bcl-2 depletion will drive maladaptive mitochondrial remodeling responses including autophagy and the disruption of the MITO fission/fusion balance as studied in Aim 3. This work critically explores the mechanisms of cardiac injury during reperfusion of ETC-mediated injury to MITO from ischemia, both direct oxidative injury from the damaged ETC and injury via downstream effectors of ETC- dependent damage including bcl-2.

描述（由申请人提供）： 心肌线粒体（MITO）是心肌缺血再灌注损伤的重要介质。在缺血期间，MITO维持由线粒体电子传递链（ETC）介导的损伤。我们的前期工作发现了缺血时ETC驱动MITO损伤的两种主要机制。首先，ETC本身在复合体I和复合体III处受损。第二，抗凋亡肽bcl-2从MITO中耗尽。我们发现，当在缺血期间使用抑制剂来阻断ETC时，对MITO的这种损害被阻止。更值得注意的是，当MITO在缺血期间受到保护时，REP后测量的梗死面积大幅减少。 由于缺血过程中ETC驱动的损伤，MITO成为再灌注过程中心肌细胞损伤的效应器。我们推测，这两种机制的内皮依赖性缺血性损伤占主导地位的心脏再灌注损伤。在再灌注开始时，受损的MITO产生氧化损伤，经历灾难性的渗透性变化并激活细胞死亡程序。导致这些有害的全球反应的机制被确定，并将导致在早期和后期的再灌注治疗干预的策略。 在这项建议的初步工作中，我们发现，虽然ETC已经持续损伤，但在再灌注期间直接操纵线粒体功能的干预可以减少心脏损伤。我们专注于机制驱动的方法，直接调节代谢，使用药理学和遗传调节线粒体功能，包括使用复合物I的短暂和部分阻断。实验方法被设计为绕过上游信号级联，而是直接与心脏损伤的最终靶点和效应器MITO相互作用。我们提出，在再灌注开始时，受损ETC的氧化代谢恢复，电子从复合物I转运到复合物III产生氧化剂，导致线粒体通透性转换孔打开和细胞死亡。目的1确定和研究复合物I和III内的再灌注损伤产生的网站。我们推测，在缺血过程中，依赖于ETC的MITO的bcl-2的耗竭导致线粒体外膜渗透和再灌注过程中程序性细胞死亡的激活。目的2研究bcl-2缺失在再灌注早期通透性转换介导的心脏损伤中的作用，可能有助于加强复合物I驱动的激活。 在再灌注的初始阶段通过干预保护的肌细胞在较长时间的再灌注期间仍然对MITO驱动的细胞死亡敏感。我们假设，MITO与缺血损伤的ETC和bcl-2耗竭的持续性将驱动适应不良的线粒体重塑反应，包括自噬和MITO分裂/融合平衡的破坏，如目的3中所研究的。这项工作批判性地探索了在由缺血引起的ETC介导的对MITO的损伤的再灌注期间的心脏损伤的机制，包括来自受损ETC的直接氧化损伤和经由ETC依赖性损伤的下游效应物（包括bcl-2）的损伤。