Mitochondrial Permeability Transition as a Target for Cardioprotection in Heart F

描述(申请人提供)：心肌梗死后的心脏重构是心肌损伤后的初始心肌肥大反应，并最终演变为心力衰竭。早期适应性肥厚的减弱可转化为心力衰竭反应的减弱，因此了解心脏重构进展为心力衰竭的分子和细胞机制至关重要。线粒体功能障碍是心室重构/心力衰竭过程中收缩功能丧失的核心，被认为是由于细胞信号分子AMP激活的蛋白激酶(AMPK)和过氧化物酶体增殖物激活受体(PPAR)共激活因子-1α(PGC-1α)失活而引起的。线粒体通透性转换孔(MPTP)的开放是细胞死亡的终末效应，与线粒体分裂和融合平衡的改变导致线粒体片段化增加有关。在这个提议中，我们假设AMPK/PGC-1α级联的变化触发MPTP开放，导致梗死后心脏重构中的心功能障碍；MPTP的调节通过AMPK/PGC-1α与孔隙复合体的直接相互作用和/或间接通过AMPK诱导的亲环素D的乙酰化来实现。为了验证我们的假设，我们将使用在体大鼠心肌梗死后重构模型和大鼠心肌细胞肥大的体外模型来研究完整的心脏、培养的心肌细胞和分离的线粒体。我们在所提出的动物和细胞模型以及必要的技术方面拥有丰富的经验，以研究心脏疾病中的线粒体功能，并开发新的药物和条件保护策略。该建议的具体目的是：(1)检测心肌梗死后重构进展到心力衰竭是否与MPTP开放增加和线粒体碎裂有关；(2)确定MPTP的形成是否受AMPK/PPARpha通路在心脏重构中的调节；(3)确定抑制MPTP在心肌梗死后重构过程中是否具有长期保护作用。拟议的研究将确定特定的线粒体适应和改变，并有助于开发治疗心肌梗死后心力衰竭的新治疗策略。 公共卫生相关性：拟议的研究旨在阐明线粒体介导的心功能障碍与梗死后重塑进展为心力衰竭的机制。特别是，线粒体通透性转换孔(MPTP)开放/线粒体碎裂与心功能障碍的关系将在一个在体心肌梗死后重构模型和一个体外心肌细胞肥大模型中进行研究。由于线粒体通过细胞凋亡和坏死在细胞死亡中起关键作用，因此防止或逆转MPTP的开放对于保护心脏免受心脏疾病的损害至关重要。因此，其心脏保护作用的特效性。 主要MPTP调节蛋白亲环素D的抑制剂sanglife hrin A将在本研究中用于预防心脏重塑/心力衰竭。

DESCRIPTION (provided by applicant): Cardiac remodeling following myocardial infarction is the initial myocardial hypertrophic response which follows myocardial injury and the eventual evolution to heart failure. Attenuation of the early adaptive hypertrophy can be translated into attenuation of heart failure response such that understanding the molecular and cellular mechanisms underlying progression of cardiac remodeling to heart failure is of crucial importance. Mitochondrial dysfunction is central to the loss of contractile function during ventricular remodeling/heart failure that are thought to be induced as a result of inactivation of cell signaling molecules, AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor (PPAR) coactivator-1alpha (PGC-1alpha). Mitochondrial permeability transition pore (MPTP) opening has been shown to be an end-effector for cell death that is associated with increased mitochondrial fragmentation due to alterations in the balance between fission and fusion of mitochondria. In this proposal, we hypothesize that the alterations in the AMPK/PGC-1alpha cascade trigger MPTP opening leading to cardiac dysfunction in post-infarction cardiac remodeling; modulation of the MPTP occurs through a direct interaction of AMPK/PGC-1alpha with the pore complex and/or indirectly, through AMPK-induced acetylation of cyclophilin D. To test our hypothesis we will study the intact heart, cultured cardiomyocytes and isolated mitochondria using an in vivo rat model of post-infarction remodeling and an in vitro model of rat cardiomyocyte hypertrophy. We have extensive experience with the proposed animal and cell models, and the necessary techniques to study mitochondrial function in cardiac diseases, and develop new pharmacological and conditional strategies for cardioprotection. The specific aims of this proposal are to: (1) Examine whether progression of post-infarction remodeling to heart failure is associated with increased MPTP opening and mitochondrial fragmentation; (2) Determine whether MPTP formation is regulated by the AMPK/PPARalpha pathway in cardiac remodeling; (3) Define whether inhibition of MPTP has long-term protective effects during post-infarction remodeling. The proposed studies will identify the specific mitochondrial adaptations and alterations, and help develop new therapeutic strategies for treatment of post-myocardial infarction heart failure. PUBLIC HEALTH RELEVANCE: The proposed studies are aimed at elucidating the mechanisms involved in mitochondria-mediated cardiac dysfunction with progression of post-infarction remodeling to heart failure. Particularly, the relationship between mitochondrial permeability transition pore (MPTP) opening/mitochondrial fragmentation and cardiac dysfunction will be investigated in an in vivo model of post-infarction cardiac remodeling and an in vitro model of cardiomyocyte hypertrophy. Since the mitochondria play a critical role in cell death through apoptosis and necrosis, prevention or reversal of MPTP opening is crucial to protect the heart against cardiac diseases. Therefore, the cardioprotective effects of the specific inhibitor for the main MPTP regulatory protein cyclophilin D, sanglifehrin A will be used in the present study to guard the heart against ventricular remodeling/heart failure.