MCL-1 is a critical regulator of mitochondrial dynamics and function in myocytes

MCL-1 是肌细胞线粒体动力学和功能的关键调节因子

• 批准号: 9245917
• 负责人: Asa B. Gustafsson
• 金额: $ 38.75万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-02-01 至 2021-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9245917
• 关键词: Affect; Apoptosis; Apoptotic; Autophagocytosis; Autophagosome; BCL-2 Protein; Bioenergetics; Calcium; Cardiac; Cardiac Myocytes; Cardiovascular Diseases; Cell Death; Cell physiology; Cells; Cellular biology; Clinical Management; Contracts; DNA Damage; Data; Defect; Development; Disease; Disease Progression; Ensure; Environment; Excision; Fasting; Future; Goals; Health; Heart; Heart Diseases; Heart failure; Homeostasis; Impairment; In Vitro; Knowledge; Location; Mediating; Membrane Potentials; Mitochondria; Mitochondrial Matrix; Molecular; Molecular Biology; Monitor; Morphology; Muscle Cells; Myocardial Infarction; Myocardium; Necrosis; Nutrient; Outer Mitochondrial Membrane; Oxidative Phosphorylation; Pathogenesis; Physiological; Play; Proteins; Proteomics; Reactive Oxygen Species; Recruitment Activity; Research; Role; Site-Directed Mutagenesis; Stress; Structure; Testing; base; cardiogenesis; in vivo; insight; mitochondrial dysfunction; mitochondrial membrane; mortality; mouse model; new therapeutic target; overexpression; parkin gene/protein; prevent; programs; receptor; response

Project Summary While mitochondrial dysfunction is evident in the failing heart, its precise role in disease progression is unclear and the mechanism(s) of its origin is not well understood. Mitochondria play a key role in many cellular processes, including oxidative phosphorylation, metabolite synthesis and calcium storage. They are also important regulators of cell death and monitor changes in the intracellular environment such as presence of reactive oxygen species and DNA damage. The BCL-2 proteins play a key role in regulating mitochondrial membrane permeabilization and apoptosis. We recently discovered that the anti-apoptotic BCL-2 protein MCL-1 is critical for normal mitochondrial function and cardiac homeostasis. Loss of MCL-1 in cardiac myocytes leads to rapid mitochondrial dysfunction, development of heart failure, and early mortality. Surprisingly, MCL-1 deficient myocytes display signs of necrosis rather than apoptosis as would be expected, suggesting that besides its anti- apoptotic role, MCL-1 has an essential but yet unidentified role in maintaining mitochondrial function in cardiac myocytes. We have also found that MCL-1 exists both in the outer mitochondrial membrane (MCL-1OM) and in the mitochondrial matrix (MCL-1Matrix) in the heart. While a study has implicated MCL-1OM in regulating apoptosis, the function of MCL-1Matrix is still unknown. Based on our preliminary data, we propose to study the hypothesis that MCL-1 has a dual role in maintaining cardiac mitochondrial function and health that is dependent on its mitochondrial location: MCL-1OM facilitates mitochondrial fission and mitophagy of aberrant mitochondria to prevent activation of unnecessary apoptosis, whereas MCL-1Matrix promotes mitochondrial fusion to preserve bioenergetic capacity and protect against autophagosomal degradation during nutrient limiting conditions. This hypothesis will be tested with three specific aims. In Specific Aim 1, we will characterize the role of MCL-1Matrix in regulating mitochondrial fusion, function, turnover and survival. In Specific Aim 2, we will delineate the role of MCL-1OM in regulating mitochondrial fission and turnover. We will determine if MCL-1OM interacts with Drp1 to promote asymmetrical fission and removal of damaged mitochondria and whether this is part of its pro-survival function. Finally, in Specific Aim #3, we will investigate whether MCL-1OM also functions as a receptor for LC3 to drive selective degradation of mitochondrial by autophagosomes. We will utilize both isolated cardiac myocytes and genetically modified mouse models combined with proteomics, cell and molecular biology to uncover the bi- functional roles of MCL-1OM and MCL-1Matrix in myocytes under baseline conditions and in response to challenge (fasting and myocardial infarction). These studies will provide important new insights into the relationship between mitochondrial dynamics, turnover and survival in the heart. A better understanding of how mitochondrial function is regulated in the heart under normal and disease conditions such as myocardial infarct will contribute towards future clinical management of heart disease.

项目摘要 线粒体功能障碍在失败的心脏中显而易见，但其在疾病进展中的精确作用尚不清楚 并且其起源的机制尚不清楚。线粒体在许多细胞过程中起关键作用， 包括氧化磷酸化，代谢产物合成和钙储存。他们也很重要 细胞死亡的调节剂并监测细胞内环境中的变化，例如活性氧的存在 物种和DNA损伤。 Bcl-2蛋白在调节线粒体膜中起关键作用 透化和凋亡。我们最近发现，抗凋亡Bcl-2蛋白MCL-1至关重要 对于正常的线粒体功能和心脏稳态。心肌细胞中MCL-1的损失导致快速 线粒体功能障碍，心力衰竭的发展和早期死亡率。令人惊讶的是，MCL-1缺乏 肌细胞表现出坏死的迹象，而不是预期的凋亡，这表明除了其抗抗 凋亡角色，MCL-1在维持心脏的线粒体功能中具有必不可少但尚未确定的作用 心肌细胞。我们还发现Mcl-1都存在于外部线粒体膜（MCL-1OM）和 心脏中的线粒体基质（Mcl-1matrix）。虽然一项研究已暗示MCL-1OM在调节凋亡中，但 MCL-1Matrix的功能仍然未知。根据我们的初步数据，我们建议研究假设 Mcl-1在维持心脏线粒体功能和健康方面具有双重作用，这取决于其 线粒体位置：MCL-1OM促进线粒体裂变和异常线粒体线粒体的线粒体裂变 防止激活不必要的凋亡，而MCL-1Matrix促进线粒体融合以保存 在养分限制条件下，生物能的能力并防止自噬体降解。这 假设将以三个特定目标进行检验。在特定目标1中，我们将表征MCL-1Matrix的作用 在调节线粒体融合，功能，周转和存活中。在特定目标2中，我们将描述 在调节线粒体裂变和周转方面的MCL-1OM。我们将确定MCL-1OM是否与DRP1相互作用 促进不对称的裂变并去除受损的线粒体，以及这是否是其生存的一部分 功能。最后，在特定的目标＃3中，我们将调查MCL-1OM是否还作为LC3的受体起作用 自体驱动线粒体的选择性降解。我们将使用两个孤立的心肌细胞 以及结合蛋白质组学，细胞和分子生物学结合的转基因小鼠模型，以发现Bi- MCL-1OM和MCL-1MATRIX在基线条件下的肌细胞中的功能作用，并回应挑战 （禁食和心肌梗塞）。这些研究将为关系提供重要的新见解 在心脏的线粒体动力学，周转和生存之间。更好地了解线粒体 功能在正常情况下在心脏中受到调节，心肌梗死等疾病状况将有助于 致力于心脏病的未来临床管理。