MITOCHONDRIAL FUSION FACTORS AND CARDIOMYOPATHY

线粒体融合因子与心肌病

• 批准号: 8720043
• 负责人: Gerald W. Dorn
• 金额: $ 37.24万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-12-15 至 2018-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8720043
• 关键词: Ablation; Apoptosis; Apoptotic; Autophagosome; BCL2 gene; Benign; Binding; Biochemical; Calcium; Calcium Signaling; Cardiac; Cardiac Myocytes; Cardiomyopathies; Caspase; Cell Death; Cells; Cessation of life; Charcot-Marie-Tooth Disease; Clinical; Coupling; DNA; DNA Sequence; Daughter; Dissection; Drosophila genus; Employee Strikes; Enzymes; Event; Excision; Familial Hypertrophic Cardiomyopathy; Foundations; Functional disorder; Genetic; Genotype; Heart; Heart Diseases; Heart Hypertrophy; Heart failure; Homeostasis; Human; Hypertrophic Cardiomyopathy; In Vitro; Induced Mutation; Injury; Interruption; Ischemia; Knockout Mice; Knowledge; Laboratories; Life; Link; Location; Mammalian Cell; Maps; Mediating; Mitochondria; Mitochondrial Diseases; Molecular; Mutation; Myocardial Contraction; Myocardial Infarction; Necrosis; Organ; Organelles; Outer Mitochondrial Membrane; PINK1 gene; Pathway interactions; Phosphorylation; Phosphorylation Site; Play; Poison; Population; Process; Production; Protein Family; Proteins; Quality Control; Reactive Oxygen Species; Respiration; Role; Sarcoplasmic Reticulum; Shapes; Signal Transduction; Source; Specific qualifier value; Syndrome; Testing; Therapeutic; Transgenic Mice; Tube; Work; base; cohort; free radical oxygen; heart function; in vivo; inhibitor/antagonist; killings; loss of function; loss of function mutation; mitochondrial permeability transition pore; mouse model; mutant; novel; overexpression; oxidative damage; parkin gene/protein; prevent; programs; public health relevance; receptor; respiratory; senescence

DESCRIPTION (provided by applicant): Mitochondrial Fusion Factors and Cardiomyopathy The heart is the most mitochondrial rich of all mammalian organs; mitochondrial ATP fuels cardiac excitation- contraction coupling. Paradoxically, mitochondria are also key pathological orchestrators of apoptotic and programmed necrotic cell death in myocardial infarction or heart failure, and are sources of cardiotoxic reactive oxygen species (ROS) when mitochondrial respiration is uncoupled from ATP production. Although mitochondrial respiratory dysfunction increases with organelle and cardiac senescence, it can be moderated by functional complementation achieved through exchange of mitochondrial contents i.e. through cyclic organelle fusion, fission, and selective removal of depolarized daughter organelles. In accordance with this paradigm we found that genetic interruption of mitochondrial fusion provokes not only organelle fragmentation (by unopposed fission), but striking accumulation of toxic ROS-producing organelles. Further, by DNA sequencing a large hypertrophic cardiomyopathy (HCM) cohort my laboratory discovered the first genetic evidence linking a mitochondrial fusion/fission factor and heart disease, a rare R400Q mutation in the mitochondrial fusion factor mitofusin 2 (Mfn2). Other Mfn2 mutations cause Charcot-Marie-Tooth Syndrome, but not heart disease. By assessing the consequences of recombinantly expressed Mfn2 Q400 in mammalian cells and Drosophila heart tubes we found that it is a dominant inhibitor of normal Mfn1 and Mfn2, inducing mitochondrial fragmentation and provoking cardiomyopathy and heart failure. We postulate that loss of Mfn2 function is cardiomyopathic not because it induces mitochondrial fragmentation, but because mitochondrial fusion in general, and specifically Mfn2, plays a central role in mitochondrial quality control. Here, we will investigate the mechanisms for heart disease caused by loss of Mfn2 function. In Aim #1 we explore the organelle, cellular, and organ-level consequences of mitochondrial fragmentation caused by loss of organelle fusion (conditional Mfn1/Mfn2 cardiac knockout mice) vs. increased organelle fission (conditional Dlp1 transgenic mice). We also determine if programmed cardiomyocyte death after I-R injury can be modulated by forced mitochondrial fusion (Mfn1 or Mfn2 transgenic mice) or preventing mitochondrial fission (cardiac Dlp1 knockout mice). In Aim #2 we perform an in vitro and in vivo molecular dissection of the role of Mfn2 in PINK1-Parkin mediated mitochondrial culling, examining the hypothesis that Mfn2 is both a PINK1 substrate and the mitochondrial receptor for Parkin on depolarized mitochondrial. In Aim #3 we apply this knowledge to determine the mechanism by which the human HCM-linked Mfn2 400Q mutation induces hypertrophic cardiomyopathy using human-in-mouse models. Together, results of this work will greatly expand our understanding of mitochondrial fusion and fission in normal heart function, will define the biochemical and cellular mechanisms by which impaired mitochondrial fusion causes clinical and experimental heart disease, and will establish a foundation for a rational therapeutic approach to an entirely new class of rare heritable HCM caused by Mfn2 mutations.

描述（由申请人提供）：线粒体融合因子和心肌病的心脏是所有哺乳动物器官中最丰富的线粒体；线粒体ATP燃料心脏激发 - 收缩耦合。矛盾的是，线粒体也是心肌梗死或心力衰竭中凋亡和编程坏死细胞死亡的关键病理编排，当线粒体呼吸与ATP的产生中脱离线粒体呼吸时，是心脏毒性活性氧（ROS）的来源。尽管线粒体呼吸功能障碍会随细胞器和心脏衰老的增加而增加，但可以通过通过线粒体含量的交换，即通过循环细胞器融合，裂变，裂变和选择性去除去极化的女儿细胞来实现的功能互补来调节。根据这种范式，我们发现线粒体融合的遗传中断不仅会引起细胞器碎片（通过无反应的裂变），而且会引起有毒ROS产生的细胞器的惊人积累。此外，通过将大型肥厚心肌病（HCM）队列进行DNA测序，我的实验室发现了第一个将线粒体融合/裂变因子和心脏病联系起来的遗传证据，这是一种罕见的R400Q突变，这是线粒体融合因子Mitofusin 2（MFN2）中的罕见R400Q突变。其他MFN2突变会引起charcot-marie-tooth综合征，而不是心脏病。通过评估在哺乳动物细胞和果蝇心管中重组表达的MFN2 Q400的后果，我们发现它是正常MFN1和MFN2的主要抑制剂，诱导了线粒体碎片，并引起心肌病和心力衰竭。我们假设MFN2功能的丧失是心肌疗法的，不是因为它诱导了线粒体碎片化，而是因为线粒体融合一般，特别是MFN2在线粒体质量控制中起着核心作用。在这里，我们将研究由MFN2功能丧失引起的心脏病的机制。在AIM＃1中，我们探索了由细胞体融合（条件MFN1/MFN2心脏敲除小鼠）与细胞器裂变（条件DLP1转基因小鼠）相比，探索线粒体碎片的细胞器，细胞和器官水平的后果。我们还确定I-R损伤后编程的心肌细胞死亡是否可以通过强迫线粒体融合（MFN1或MFN2转基因小鼠）进行调节或预防线粒体裂变（心脏DLP1敲除小鼠）。在AIM＃2中，我们对MFN2在Pink1-Parkin介导的线粒体culling中的作用进行了体外和体内分子解剖，研究了MFN2既是PINK1底物，又是parkin的线粒体受体的假设，用于parkin。在AIM＃3中，我们应用了这些知识来确定与人类HCM相关的MFN2 400Q突变通过人类鼠模型诱导肥厚性心肌病的机制。这项工作的结果将大大扩展我们对线粒体融合和正常心脏功能中的裂变的理解，将定义生化和细胞的机制，通过这些机制，线粒体融合受损会导致临床和实验性心脏病，并将建立一个合理的治疗方法，从而建立一个由罕见的稀有性治疗方法引起的，由罕见的新型Hersherable Hershialable herabyable herableable hercm sut sut sut sut s hcn2 sut 2 sut。