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

基本信息

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
项目类别：
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

项目摘要

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（由申请人提供）：抗凋亡 Mcl-1 的心肌细胞特异性缺失会导致致命的心肌病，随后出现心肌收缩力丧失、线粒体超微结构异常和促凋亡效应子的共同缺失。 Bax 和 Bak 挽救了 Mcl-1 缺失引起的死亡和心脏功能受损；然而，Mcl-1、Bax 和 Bak 缺陷 (TKO) 心脏的线粒体仍然表现出超结构异常和线粒体呼吸缺陷。 MCL-1 促进正常线粒体功能并促进心肌细胞中的心肌细胞存活我们已经确定 MCL-1 存在于表现出可分离功能的不同线粒体定位中：线粒体外膜。 (OMM) 定位的 MCL-1 抑制细胞死亡，基质定位的 MCL-1 促进正常的线粒体生理学。然而，这些形式的 MCL-1 如何有助于调节心肌细胞的存活和线粒体功能仍不清楚。 MCL-1 在可分离的线粒体定位中发挥作用：外膜形式可防止细胞凋亡，基质定位形式通过支持能量代谢来维持有效的心肌细胞线粒体功能。解决以下重要且创新的问题：目标 1：MCL-1 如何调节心肌细胞的死亡？成人心脏中 Mcl-1 的诱导缺失会导致心肌细胞损失和纤维化。 1 通过防止 BAX/BAK 介导的细胞凋亡来促进心肌细胞存活所需。目标 2：MCL-1 的不同定位如何有助于调节心肌细胞中的线粒体功能？即使 Bax 和 Bak 被删除，缺失也会导致线粒体功能障碍，并导致模型细胞系中的脂肪酸 (FA) 氧化缺陷。我们假设，在心肌细胞中，基质定位的 MCL-1 可促进正常的线粒体 FA 氧化。 1 表达通过预防死亡和维持正常的心肌细胞能量代谢来抑制心力衰竭？在心力衰竭的晚期，心肌能量代谢从主要的 FA 氧化转变为糖酵解和糖酵解增加。由于 MCL-1 可以阻止细胞死亡并调节心肌细胞线粒体功能，因此有证据表明 MCL-1 靶向突变体的过度表达将揭示 MCL-1 不仅可以阻止心肌细胞死亡，还有助于维持心肌细胞能量代谢。我们拥有开展拟议研究的理想条件，因为我们拥有研究 MCL-1 多种功能的体外和体内专业知识，开发了支持研究的基本小鼠遗传模型，并且在表征方面拥有丰富的经验。 MCL-1 在心脏功能中的作用在本研究结束时，我们将对如何利用 MCL-1 的多种功能促进心肌细胞存活有新的认识，并可能揭示避免与 MCL 化疗抑制相关的潜在心脏毒性的方法。 -1。