Crosstalk between mitochondrial permeability transition and ETC supercomplexes in myocardial infarction

抽奖 冠心病是世界范围内发病率和死亡率的主要原因。冠脉适时恢复 再灌流是保护心脏的唯一有效的治疗干预措施。 心肌梗塞(MI)。目前尚无有效的预防心肌缺血再灌注的治疗方法。 (IR)受伤。线粒体功能的丧失在IR诱导的细胞死亡中起着关键作用 线粒体功能的保护和恢复是细胞在心脏中生存的关键。然而，有限的 对线粒体介导的细胞死亡机制的了解掩盖了新的 线粒体靶向的心脏保护化合物。心脏IR增加钙、活性氧自由基 (ROS)和线粒体中的无机磷水平诱导线粒体通透性转变(MPT)。 同时线粒体膜内非特异性病理性MPT孔开放。高 线粒体ROS(MtROS)也可分解线粒体超复合体(SCs)，主要原因是 心磷脂(CL)的氧化，一种独特的线粒体磷脂。SCS是一种大型超分子复合体 含有单独的电子传输链(ETC)复合体。根据固态模型，组件 干细胞在整个ETC中提供高效的电子通量；它增加了ATP的合成，并显著 由于ETC络合物之间的扩散距离较短，减少了电子泄漏和mtROS的产生。这个 MPT诱导和SC降解之间的因果关系尚未建立。我们 假设MPT在线粒体SCs的解体中起因果作用，导致线粒体SCs减少 心脏IR中的能量代谢和细胞死亡。我们认为MPT诱导的线粒体肿胀增敏 CL与ROS攻击导致SC退化有关。具体目标如下：(1)确定 心肌梗死后MPT发生的时间、SCs的解体和损伤的进展。我们将调查这一关联 利用体内动物模型研究MPT开孔与SC降解之间的关系，以及随着IR损伤的进展 冠状动脉结扎致心肌梗死伴/不伴再通。我们还将讨论WT和Tafazzin 敲除(TazKD)小鼠心脏IR以区分CL氧化诱导的SC组装的变化与 CL缺乏。(2)考察MPT诱导与SC解体之间的因果关系 以应对氧化应激。我们将用CYP-D(Ppif)和/或他法津对心肌细胞/线粒体进行试验 缺乏氧化应激，以阐明MPT和SC分解之间的因果关系。在……里面 此外，在MPT诱导剂/阻滞剂存在的情况下，心肌线粒体将被氧化的CL处理，以揭示 MPT和CL氧化在SC降解中的因果作用。(3)定义是否抑制mpt和mtROS 清除对心肌梗死后损伤有协同保护作用。这些研究将确定联合治疗是否 同时靶向mtROS和MPT对心肌IR具有协同的心脏保护作用。MPT 在活体心脏IR期间，抑制剂将单独或与mtROS清除剂联合使用。在……里面 此外，WT和TazKD心脏将在存在MPT抑制剂和/或mtROS的情况下进行体外IR 食腐动物。总体而言，阐明MPT和SC降解之间的串扰机制将提供新的 深入了解心肌缺血再灌注期间线粒体介导的细胞死亡的分子基础。这样做的结果是 该项目将允许开发新的治疗策略来预防心肌缺血再灌注损伤，并改善临床 靶向线粒体对急性心肌梗死患者的影响。

ABSRACT Coronary heart disease is the leading cause of morbidity and mortality worldwide. Timely restoration of coronary perfusion known as reperfusion is the only effective therapeutic intervention for protecting the heart from myocardial infarction (MI). Currently, there is no effective therapy for preventing cardiac ischemia-reperfusion (IR) injury. The loss of mitochondrial function plays a crucial role in IR-induced cell death suggesting that protection and restoration of mitochondrial function is pivotal to cell survival in the heart. However, limited knowledge of the mechanisms underlying mitochondria-mediated cell death obscures the development of new mitochondria-targeted cardioprotective compounds. Cardiac IR increases calcium, reactive oxygen species (ROS), and inorganic phosphate levels in mitochondria that induce mitochondrial permeability transition (MPT) concurrently with opening of the non-specific pathological MPT pores in the inner mitochondrial membrane. High mitochondrial ROS (mtROS) also may disintegrate mitochondrial supercomplexes (SCs), predominantly due to oxidation of cardiolipin (CL), a unique mitochondrial phospholipid. SCs are large supramolecular complexes containing individual electron transport chain (ETC) complexes. According to the solid-state model, the assembly of SCs provides high-efficiency electron flux throughout the ETC; it increases ATP synthesis and significantly reduces electron leakage and mtROS production due to short diffusion distances between ETC complexes. The cause-and-effect relationship between MPT induction and SC degradation has not yet been established. We hypothesize that the MPT plays a causal role in the disintegration of mitochondrial SCs, leading to diminished energy metabolism and cell death in cardiac IR. We propose that MPT-induced mitochondrial swelling sensitizes CL to the ROS attack leading to degradation of SCs. The Specific Aims are as follows: (1) Determine the timing of MPT, disintegration of SCs and progression of post-MI injury. We will investigate the association between MPT pore opening and SC degradation, with progression of IR injury, using the animal model of in vivo MI induced by coronary artery ligation with/without subsequent reperfusion. We will also subject WT and tafazzin knockdown (TazKD) mice to cardiac IR to distinguish changes in SC assembling induced by CL oxidation versus CL deficiency. (2) Examine the cause-and-effect relationship between the MPT induction and SC disintegration in response to oxidative stress. We will subject cardiomyocytes/mitochondria with CyP-D (Ppif) and/or tafazzin deficiency to oxidative stress to clarify a cause-and-effect relationship between MPT and SC disintegration. In addition, cardiac mitochondria will be treated with oxidized CL in the presence of MPT inducers/blockers to reveal a causal role of MPT versus CL oxidation in SC degradation. (3) Define if inhibition of MPT, and mtROS scavenging protect synergistically against post-MI injury. These studies will establish whether combined therapy simultaneously targeting mtROS and MPT exerts synergistic cardioprotective effects on cardiac IR. The MPT inhibitor will be administered alone or in combination with mtROS scavengers during in vivo cardiac IR. In addition, WT and TazKD hearts will be subjected to ex vivo IR in the presence of the MPT inhibitor and/or mtROS scavengers. Overall, elucidating the crosstalk mechanisms between MPT and SC degradation will provide new insights into the molecular basis of mitochondria-mediated cell death during cardiac IR. The outcome of this project will allow development of new therapeutic strategies to prevent myocardial IR injury, and improve clinical consequences in patients with acute myocardial infarction through targeting mitochondria.