Regulation of Cardiac Death and Energy Metabolism by MCL-1

MCL-1 对心源性死亡和能量代谢的调节

• 批准号: 8886812
• 负责人: JOSEPH T. OPFERMAN
• 金额: $ 47.93万
• 依托单位: ST. JUDE CHILDREN'S RESEARCH HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-07 至 2019-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8886812
• 关键词: Adult; Apoptosis; Apoptotic; Attenuated; BAX gene; BCL2 gene; Biochemical Genetics; Cardiac; Cardiac Death; Cardiac Myocytes; Cardiomyopathies; Cardiotoxicity; Cardiovascular system; Cell Death; Cell Line; Cessation of life; Chronic; Data; Ectopic Expression; Energy Metabolism; Exhibits; Family member; Fibrosis; Genetic Models; Glucose; Glycolysis; Goals; Heart; Heart failure; In Vitro; Isoproterenol; Lead; Mediating; Membrane; Metabolic; Metabolism; Mitochondria; Modeling; Morbidity - disease rate; Mus; Myocardial; Myocardial Contraction; Necrosis; Outer Mitochondrial Membrane; Physiology; Positioning Attribute; Process; Production; Regulation; Research; Respiration; Role; Staging; Stress; Structural defect; Testing; Therapeutic; Toxic effect; United States; United States National Institutes of Health; Work; cancer therapy; experience; fatty acid oxidation; genetic approach; in vivo; inhibitor/antagonist; innovation; mitochondrial dysfunction; mortality; mutant; novel therapeutics; overexpression; oxidation; prevent; public health relevance; self-renewal

 DESCRIPTION (provided by applicant): Cardiomyocyte-specific deletion of anti-apoptotic Mcl-1 results in a fatal cardiomyopathy preceded by loss of cardiac contractility, abnormal mitochondrial ultrastructure, and impaired respiration. Co-deletion of the pro- apoptotic effectors Bax and Bak rescued the lethality and impaired cardiac function induced by Mcl-1-deletion; however, mitochondria from Mcl-1, Bax, and Bak-deficient (TKO) hearts still exhibited ultra-structural abnormalities and deficient mitochondrial respiration. These data suggest that MCL-1 facilitates normal mitochondrial function and promotes cardiomyocyte survival in cardiomyocytes. We have identified that MCL-1 resides in distinct mitochondrial localizations exhibiting separable functions: outer mitochondrial membrane (OMM)-localized MCL-1 inhibits cell death and matrix-localized MCL-1 promotes normal mitochondrial physiology. However, how these forms of MCL-1 contribute to regulating cardiomyocyte survival and mitochondrial function remains unclear. Our central hypothesis is that in cardiomyocytes MCL-1 functions at separable mitochondrial localizations: the outer membrane form prevents apoptosis and the matrix-localized form maintains efficient cardiomyocyte mitochondrial function by supporting energy metabolism. We propose to use biochemical and genetic approaches to tackle the following significant and innovative questions: Aim 1: How does MCL-1 regulate the death of cardiomyocytes? Inducible deletion of Mcl-1 in adult hearts leads to the loss of cardiomyocytes and fibrosis. Our working hypothesis is that OMM-localized MCL-1 is required to promote cardiomyocyte survival by preventing BAX/BAK-mediated apoptosis. Aim 2: How do MCL- 1's different localizations contribute to regulating mitochondrial function in cardiomyocytes? MCL-1 loss leads to mitochondrial dysfunction even when Bax and Bak are deleted and causes defective fatty acid (FA) oxidation in model cell lines. We postulate that in cardiomyocytes matrix-localized MCL-1 facilitates normal mitochondrial FA oxidation. Aim 3. Can ectopic MCL-1 expression inhibit cardiac failure by preventing death and maintaining normal cardiomyocyte energy metabolism? In the advanced stages of heart failure myocardial energy metabolism shifts from primarily FA oxidation to increased glycolysis and there is evidence of cardiomyocyte death. Since, MCL-1 blocks both cell death and modulates cardiomyocyte mitochondrial function, we hypothesize that overexpression of MCL-1 targeted mutants will reveal that MCL-1 not only blocks cardiomyocyte death, but helps maintain cardiomyocyte energy metabolism. We are ideally positioned to carry out the proposed studies as we possess expertise in studying MCL-1's diverse functions in vitro and in vivo, have developed essential mouse genetic models to support the studies, and are experienced in characterizing MCL-1's role in cardiac function. At the end of this study, we will have a new understanding of how MCL-1's diverse functions may be utilized to promote cardiomyocyte survival and may reveal ways to avoid potential cardiac toxicities associated with chemotherapeutic inhibition of MCL-1.

 描述（由应用提供）：抗凋亡MCL-1的心肌细胞特异性缺失导致致命的心肌病在心脏收缩率丧失，线粒体超微结构异常和呼吸受损之前。促凋亡效应的共同删除 Bax和Bak反应了MCL-1脱落引起的致命性和心脏功能受损。但是，来自MCL-1，BAX和BAK缺陷（TKO）心脏的线粒体仍然暴露于超结构异常和线粒体呼吸不足。这些数据表明MCL-1的最爱正常线粒体功能并促进心肌细胞中心肌细胞的存活。我们已经确定MCL-1驻留在不同的线粒体局部位置中，表现出不同的功能：外部线粒体膜（OMM）局部化的MCL-1抑制细胞死亡，并抑制基质 - 位置的MCL-1促进正常的线粒体生理。但是，这些形式的MCL-1如何有助于调节心肌细胞存活和线粒体功能尚不清楚。我们的中心假设是，在心肌细胞中，MCL-1在单独的线粒体局部局部功能：外膜形式可防止细胞凋亡，而基质 - 定位形式通过支持能量代谢来维持有效的心肌细胞功能。我们建议使用生化和遗传方法来解决以下重大和创新的问题：目标1：MCL-1如何调节心肌细胞的死亡？ MCL-1在成人心脏中的诱导缺失导致心肌细胞和纤维化的丧失。我们的工作假设是，需要通过防止Bax/Bak介导的细胞凋亡来促进心肌细胞存活。 AIM 2：MCL-1的不同局部化如何有助于确定心肌细胞中的线粒体功能？即使删除了Bax和Bak，MCL-1损耗也会导致线粒体功能障碍，并导致模型细胞系中有缺陷的脂肪酸（FA）氧化。我们假设在心肌细胞中矩阵定位的MCL-1最爱正常线粒体FA氧化。目标3。生态MCL-1表达能否通过预防死亡和维持正常心肌细胞能量代谢来抑制心脏衰竭？在心力衰竭的高级阶段，心肌能量代谢从原发性FA氧化转移到增加糖酵解，并且有迹象表明心肌细胞死亡。由于MCL-1会阻止细胞死亡并调节心肌细胞线粒体功能，因此我们假设MCL-1靶向突变体的过表达将表明MCL-1不仅会阻止心肌细胞死亡，而且有助于维持心肌细胞能量代谢。理想的位置可以进行拟议的研究，因为我们在研究Mcl-1的体外和体内具有专业知识，已经开发了基本的小鼠遗传模型来支持研究，并且在表征MCL-1在心脏功能中的作用方面经验丰富。在这项研究结束时，我们将对如何利用MCL-1的潜水功能来促进心肌细胞的生存，并可能揭示避免与MCL-1化学疗法抑制相关的潜在心脏毒性的方法。