Integration of Pre-Mitochondrial Death Signals by ARC

ARC 整合线粒体前死亡信号

• 批准号: 7020003
• 负责人: Richard N Kitsis
• 金额: $ 40.46万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7020003
• 关键词: BCL2 gene /protein; Bax gene /protein; apoptosis; cardiac myocytes; cytoprotection; gene deletion mutation; gene expression; gene targeting; genetically modified animals; green fluorescent proteins; laboratory mouse; membrane channels; membrane potentials; mitochondrial membrane; molecular pathology; muscle proteins; myocardial infarction; myocardium disorder; protein structure function; protein transport; reperfusion

DESCRIPTION (provided by applicant): Inhibition of cardiac myocyte apoptosis during ischemia-reperfusion and heart failure decreases myocardial damage, left ventricular remodeling, contractile dysfunction and, in some cases, mortality. Little is known, however, about the molecular regulation of apoptosis specifically in cardiac myocytes. The central death machinery has been highly conserved from worm to human and differs little among various cell types. Despite this, apoptosis is often regulated in a cell type- and stimulus-specific manner, the basis of which is poorly understood. ARC (Apoptosis Represser with a CARD (caspase recruitment domain)) is an endogenous inhibitor of apoptosis that is expressed primarily in cardiac and skeletal muscle. Our preliminary studies demonstrate that ARC suppresses both the death receptor and mitochondrial pathways through novel protein-protein interactions. In the death receptor pathway, ARC binds directly to Fas and FADD to inhibit the formation of the Death Inducing Signaling Complex which is required for death receptor signaling. In the mitochondrial pathway, ARC binds directly to Bax to inhibit Bax activation and translocation to the mitochondria in response to apoptotic stimuli. The ability of ARC to simultaneously antagonize both central death pathways is unique and suggests that this inhibitor may function as a master-repressor of apoptosis in cardiac myocytes. This application tests the central hypothesis that ARC serves as a critical regulator of cardiac myocyte apoptosis through Bax, Bak, and mitochondrial-dependent mechanisms. The objectives are to determine (a) the mechanisms by which ARC inhibits apoptotic pre-mitochondrial and mitochondrial events; and (b) the biological significance of this inhibition for cardiac myocyte survival in pathological contexts. Aim 1 seeks to delineate mechanisms by which ARC inhibits Bax translocation, Bak activation, and apoptotic mitochondrial events. Aim 2 uses Bax and Bak knockout mice to define the role of these downstream ARC effectors in acute ischemia-reperfusion injury and post-infarct remodeling in vivo. Aim 3 uses ARC knockout mice to determine if the absence of ARC causes a baseline cardiomyopathy and/or exacerbates acute ischemia reperfusion injury and post-infarct remodeling in vivo. In addition, this aim tests whether these phenotypes can be rescued by simultaneous deletion of Bax or Bak. These aims constitute a highly focused and integrated program that examines critical aspects of ARC from the single molecule to its role in the intact animal. The resulting information will advance our understanding of apoptosis in the myocardium and may provide the basis for novel cardiac-specific therapies for myocardial infarction and heart failure.

描述（由申请人提供）：在缺血-再灌注和心力衰竭期间抑制心肌细胞凋亡可减少心肌损伤、左心室重塑、收缩功能障碍，在某些情况下还可降低死亡率。然而，对心肌细胞凋亡的分子调控知之甚少。从蠕虫到人类，中央死亡机制一直高度保守，在各种细胞类型之间几乎没有差异。尽管如此，细胞凋亡通常以细胞类型和刺激特异性的方式调节，其基础知之甚少。ARC（Apoptosis Repressor with a CARD（caspase recruitment domain））是一种内源性凋亡抑制剂，主要在心肌和骨骼肌中表达。我们的初步研究表明，ARC抑制死亡受体和线粒体途径，通过新的蛋白质-蛋白质相互作用。在死亡受体途径中，ARC直接与Fas和FADD结合，以抑制死亡受体信号传导所需的死亡诱导信号复合物的形成。在线粒体途径中，ARC直接与Bax结合以抑制Bax活化和易位至线粒体以响应凋亡刺激。ARC同时拮抗两种中枢死亡途径的能力是独特的，表明这种抑制剂可能作为心肌细胞凋亡的主阻遏物发挥作用。本申请测试了中心假设，即ARC通过Bax、巴克和细胞依赖性机制作为心肌细胞凋亡的关键调节因子。目的是确定（a）ARC抑制凋亡前线粒体和线粒体事件的机制;和（B）这种抑制在病理环境中对心肌细胞存活的生物学意义。目的1试图阐明ARC抑制Bax易位、巴克激活和线粒体凋亡事件的机制。目的2利用Bax和巴克基因敲除小鼠来确定这些下游ARC效应物在体内急性缺血再灌注损伤和梗死后重构中的作用。目的3使用ARC敲除小鼠来确定ARC的缺失是否导致基线心肌病和/或加重体内急性缺血再灌注损伤和梗死后重塑。此外，该目的测试这些表型是否可以通过同时缺失Bax或巴克来拯救。这些目标构成了一个高度集中和综合的计划，检查ARC的关键方面，从单个分子到其在完整动物中的作用。由此产生的信息将促进我们对心肌细胞凋亡的理解，并可能为心肌梗死和心力衰竭的新型心脏特异性治疗提供基础。