Cytoskeletal-Based Survival Pathways in Myocardium

描述（由申请人提供）：保护心肌细胞免于死亡是降低心肌梗死相关死亡率的最佳方法。尽管描述了许多能够保护肌细胞免受致命伤害的干预措施，但由于缺乏对心脏对压力反应的综合理解，在临床领域应用这些干预措施的潜在希望仍然没有实现。一个仍然知之甚少的特定领域是心肌应激如何通过肌层膜转导成单个肌细胞水平的保护信号。我们实验室的长期目标是更好地了解心肌细胞水平上负责心脏保护信号的细胞和分子机制。这一建议的目的是证明通过基于细胞骨架的信号传导途径可以被激活，以增强肌细胞在致死性缺血性损伤中的存活。局灶黏附激酶（FAK）已被认为是心脏和其他组织中细胞存活信号通路的关键介质。最近的数据表明，存在包括FAK、细胞骨架和其他亚细胞信号蛋白在内的综合信号通路，这些信号蛋白可以被应激放大或刺激；特别是缺血/再灌注，热休克，和/或膜受体刺激。这一提议将验证心肌应激，直接或通过受体激活，放大基于细胞骨架的信号级联，导致延长心肌细胞存活的假设。该提案的具体目标将证明：1)FAK的激活在细胞外心肌应激反应中起核心作用；2)细胞骨架通路的激活通过激活Akt实现心脏保护；3)该通路的激活发生在完整的心脏中，可能为许多已描述的心脏保护干预提供了一个共同的途径。应激激活的特异性细胞存活蛋白将在一系列综合实验中进行评估，利用重组腺病毒、生物化学和培养心肌细胞的显微镜分析，并将在完整心脏中使用分离的灌注大鼠和小鼠缺血性细胞死亡模型进行证实。对这种生存/适应途径的潜在机制的描述将增强我们对不可逆损伤的理解，并可能导致急性心肌梗死治疗中新的和创新的临床策略。

DESCRIPTION (provided by applicant): Protecting myocytes from death is the best way to lower the mortality associated with myocardial infarction. Despite the description of many interventions capable of protecting myocytes from lethal injury, the potential promise of applying these interventions in the clinical arena has remained unfulfilled due in part to a lack of an integrative understanding of the heart's response to stress. One specific area that remains poorly understood is how myocardial stress is transduced across the sarcolemmal membrane into a protective signal at the level of the individual myocyte. The long term goal of our laboratory is to understand better the cellular and molecular mechanism(s) responsible for cardioprotective signaling at the level of the myocyte. The goal of this proposal is to demonstrate that signaling through a cytoskeletal based pathway can be activated to enhance myocyte survival against lethal ischemic injury. Focal adhesion kinase (FAK) has become recognized as a key mediator of cell survival signaling pathways in heart as well as other tissues. Recent data has demonstrated that an integrated signaling pathway exists involving FAK, the cytoskeleton, and other subcelluar signaling proteins that can be amplified or stimulated by stress; specifically ischemia/reperfusion, heat shock, and/or membrane receptor stimulation. This proposal will test the hypothesis that myocardial stress, either directly or through receptor activation, amplifies a cytoskeletal- based signaling cascade that results in prolonged myocyte survival. Specific aims of the proposal will demonstrate that: 1) activation of FAK plays a central role in the response to extracellular myocardial stress; 2) activation of the cytoskeletal-based pathway results in cardioprotection through activation of Akt; and 3) activation of the pathway occurs in intact hearts and may provide a common pathway for many described cardioprotective interventions. The specific cell survival proteins activated by stress will be evaluated in a series of integrated experiments utilizing recombinant adenoviruses, biochemical, and microscopic analysis of cultured cardiomyocytes, and will be confirmed in intact hearts using isolated perfused rat and mouse models of ischemic cell death. Characterization of the underlying mechanism(s) of this survival/adaptive pathway will enhance our understanding of irreversible injury and may lead to new and innovative clinical strategies in the therapy of acute myocardial infarction.