Molecular Regulation of Mitochondrial Permeability Transition and its Role in Regulated Necrosis

项目摘要/摘要 心肌细胞的调节性坏死性死亡是心肌梗死过程中死亡的直接原因 脑梗塞。发生受监管的坏死所需的一个关键步骤是打开 线粒体通透性转换孔(MPTP)。打开MPTP，导致ATP的损失 生产、线粒体功能障碍以及最终的坏死性细胞死亡。身份识别 MPTP的组成部分已经困扰科学界30多年了。这个 线粒体膜内成孔成分及其调节因子的鉴定 MPTP对于从机制上理解调节性坏死是至关重要的。腺嘌呤核苷酸 转运蛋白(ANT)家族以前被认为是MPTP的成孔成分 在线粒体膜内，但这在基因上是错误的，当线粒体 缺乏ANT1和ANT2的患者仍需进行线粒体通透性转换。然而，这些 线粒体对MPTP开放明显不敏感。最近，我们培育出了小鼠 在肝脏中缺乏蚂蚁家族的所有三种异构体，表明线粒体中的MPTP 从蚂蚁零肝脏中分离出来的病毒更加不敏感，但毛孔最终会在 存在非常高的钙离子。令人惊讶的是，当我们用 亲环素D(CypD)抑制剂环孢素A(CsA)可抑制MPTP。环孢素A的治疗 正常情况下会使MPTP脱敏，但如果有足够的钙离子，CSA可以被克服，MPTP仍然 交战。我们现在有能力确定完全的治疗潜力 通过产生缺乏主要亚型的小鼠来完全抑制I/R损伤过程中的MPTP 蚂蚁和CypD在心中。除了蚂蚁家族和CypD，MPTP也受到调控 来自线粒体膜外的BAX和BAK。两国之间的关系 有关MPTP调节的Ants、CypD和Bax/Bak尚未定义。在这项提案中，我们的目标是 阐明它们是如何协同作用导致MPTP开放的。我们的 初步数据表明存在多种内膜成孔成分。 MPTP包括蚂蚁家族和其他一些身份不明的毛孔。我们将使用ANT NULL 线粒体更详细地探索这一假说，并旨在确定新的孔道形成 通过使用有针对性和不偏不倚的方法。总而言之，这项提案将提供 在MPTP的组成和监管方面具有关键的机械洞察力，这将揭示潜力 在心肌缺血时抑制MPTP开放以延长心肌细胞存活的策略 事件。

Project Summary/Abstract Regulated necrotic death of cardiomyocytes is the direct cause of mortality during a myocardial infarction. One crucial step that is required for regulated necrosis to occur is the opening of the mitochondrial permeability transition pore (MPTP). Opening of the MPTP, leads to loss of ATP production, mitochondrial dysfunction, and eventual necrotic cell death. Identification of the components of the MPTP has plagued the scientific community for over 30 years. The identification of the inner mitochondrial membrane pore-forming components and regulators of the MPTP is vital for the mechanistic understanding of regulated necrosis. The adenine nucleotide translocator (ANT) family was previously thought to be the pore-forming component of the MPTP within the inner mitochondrial membrane, but this was genetically disproven when mitochondria lacking ANT1 and ANT2 still underwent mitochondrial permeability transition. However, these mitochondria are significantly desensitized to MPTP opening. Recently, we generated mice lacking all three isoforms of the ANT family in liver and showed that the MPTP in mitochondria isolated from ANT null livers are even more desensitized, but the pore eventually opens in the presence of very high Ca2+. Surprisingly, when we treated the ANT null mitochondria with cyclosporine A (CsA), a cyclophilin D (CypD) inhibitor, the MPTP was inhibited. Treatment of CsA normally desensitizes the MPTP, but with enough Ca2+ CsA can be overcome and the MPTP still engages. We now have the ability to definitively determine the full therapeutic potential of complete MPTP inhibition during I/R injury by generating mice lacking the predominant isoforms of ANT and CypD in the heart. In addition to the ANT family and CypD, the MPTP is also regulated from from the outer mitochondrial membrane by Bax and Bak. The relationship between the ANTs, CypD, and Bax/Bak in regards to MPTP regulation is undefined. In this proposal, we aim to elucidate how they function in concert with one another to lead to MPTP opening. Our preliminary data suggest the existence of multiple inner membrane pore-forming components of the MPTP including the ANT family and some other unidentified pore. We will utilize ANT null mitochondria to explore this hypothesis in further detail and aim to identify the novel pore-forming component by using targeted and unbiased approaches. Together this proposal will provide crucial mechanistic insight in the composition and regulation of the MPTP that will reveal potential strategies to inhibit MPTP opening to prolong cardiomyocyte survival in the face of an ischemic event.