Molecular Identity of the Cardiac Mitochondrial Pore

描述(申请人提供)：线粒体功能障碍通常是心肌疾病的一个潜在原因。特别是，许多心脏病理与线粒体通透性的迅速和显著增加有关。这些通透性的变化引发了一系列导致心肌细胞死亡的分子事件。我们的长期目标是了解如何针对线粒体驱动的死亡机制来预防心肌疾病。线粒体通透性转换(MPT)孔是一个大的、非特异性的通道，被认为跨越两个线粒体膜，众所周知，它介导了启动线粒体驱动死亡的致命性通透性变化。MPT孔最初被认为是由外膜的电压依赖性阴离子通道(VDAC)、内膜的腺核苷酸转位酶(ANT)和基质中的调节蛋白亲环素-D(CypD)组成的。然而，尽管我们和其他人已经证明，缺乏CypD的小鼠确实对MPT和MPT介导的细胞死亡具有抵抗力，但缺乏VDAC或ANT的小鼠仍然表现出经典的MPT现象，并对细胞毒刺激做出正常反应。因此，除CypD外，MPT孔的确切分子组成仍未确定。我们已经确定线粒体磷酸载体(PIC)是一种新的CypD相互作用蛋白，并产生了强有力的初步数据，表明PIC是MPT和细胞死亡的正调控因子。因此，我们的中心假设是PIC是MPT孔的重要组成部分，因此是心肌细胞死亡的关键介质。因此，本申请的目的是利用遗传获得和功能丧失的方法来系统地评估PIC在MPT、心肌细胞死亡和心肌疾病进展中的作用。我们的具体目标如下：特定目标1：明确Pic和CypD之间的生理和功能相互作用；特定目标2：研究Pic上调是否会导致MPT和心脏病理；特定目标3：确定Pic在MPT和心肌细胞死亡中的功能需求。这项拟议研究的基本原理是，一旦确定了参与线粒体功能障碍的关键线粒体蛋白，它们就可以作为治疗一系列人类心脏病的手段。公共卫生相关性：心脏细胞死亡是人类心脏病的根本原因。这项拟议的研究旨在揭示导致心脏细胞死亡的分子机制。一旦确定了介导细胞死亡的关键蛋白，它们就可以作为治疗心脏病患者的一种手段。

DESCRIPTION (provided by applicant): Mitochondrial dysfunction is often an underlying cause of myocardial disease. In particular, many cardiac pathologies are associated with rapid and dramatic increases in mitochondrial permeability. These changes in permeability instigate a molecular chain of events that leads cardiomyocyte death. Our long-range goal is to understand how specific mechanisms of mitochondrial-driven death can be targeted for the prevention of myocardial disease. The mitochondrial permeability transition (MPT) pore, a large, non-specific channel thought to span both mitochondrial membranes, is known to mediate the lethal permeability changes that initiate mitochondrial-driven death. The MPT pore was originally proposed to consist of the voltage-dependent anion channel (VDAC) in the outer membrane, the adenine nucleotide translocase (ANT) in the inner membrane, plus a regulatory protein cyclophilin-D (CypD) in the matrix. However, while we, and others, have shown that mice lacking CypD are indeed resistant to MPT and MPT-mediated cell death, mice lacking either VDAC or ANT still exhibit a classical MPT phenomenon and respond normally to cytotoxic stimuli. Consequently, with the exception of CypD, the precise molecular component of the MPT pore has still not been defined. We have identified the mitochondrial phosphate carrier (PiC) as a novel CypD-interacting protein, and have generated strong preliminary data that the PiC is a positive regulator of MPT and cell death. Consequently, our central hypothesis is that PiC is an essential component of the MPT pore, and, therefore, a critical mediator of cardiomyocyte death. The objective of the present application, therefore, is to utilize genetic gain- and loss-of-function approaches to systematically evaluate the role of the PiC in MPT, cardiac cell death, and the progression of myocardial disease. Our specific aims are as follows: Specific Aim 1: Define the physical and functional interaction between PiC and CypD; Specific Aim 2: Examine whether PiC upregulation induces MPT and cardiac pathology; and Specific Aim 3: Determine the functional requirement for PiC in MPT and cardiac cell death. The rationale for the proposed research is that once key mitochondrial proteins that participate in mitochondrial dysfunction are identified, they can be targeted as a means of treating a whole array of human cardiac diseases. PUBLIC HEALTH RELEVANCE: The death of heart cells is an underlying cause of human heart disease. The proposed research is aimed at uncovering the molecular mechanisms that lead to heart cell death. Once the key proteins that mediate cell death are identified, they can then be targeted as a means of treating patients with heart disease.