Oxidative Stress, PKC Signaling and Heart Failure

 描述(由申请人提供)： 心力衰竭是退伍军人退伍军人在退伍军人保健系统接受治疗的首要原因。在器官水平测量的心力衰竭是由于心脏兴奋-收缩(E-C)偶联受损而导致的细胞衰竭的结果。E-C偶联的一个关键结构成分是肌细胞横行(T)-小管系统。T-管在膜兴奋、肌浆网(SR)钙离子释放的协调和同步激活以及肌肉收缩中起着重要作用。在来自动物模型和人类患者的衰竭的肌细胞中，我们和其他人已经表明，规则排列的T管系统经历了破坏性的重塑，导致细胞内异常的钙释放和心肌细胞的收缩能力受损。我们最近公布的数据有力地表明，T小管结构的完整性是一种 心肌收缩功能的关键结构决定因素。此外，我们发现， 连接蛋白-2(JP2)是一种横跨T小管和SR膜的结构蛋白，其蛋白表达是心脏疾病中T小管变形的一个原因。大量证据表明，E-C偶联受到氧化应激的损害，氧化应激在心脏病心肌细胞中升高。尽管氧化应激在心肌病中的作用是明确的，但在人类身上的抗氧化剂试验未能提供治疗益处，这表明对心脏病中氧化应激介导的途径的理解不完整，或者可能是以前临床试验中使用的错误的抗氧化剂策略。以往的报道已经提供了坚实的证据表明，蛋白激酶C(PKC)是由氧化应激激活的。在细胞水平上，PKC已被证明削弱E-C偶联。在初步研究中，PKC的激活导致心肌细胞结构和功能的改变。然而，为了找到保持心肌收缩能力的心脏病新的治疗策略，迫切需要确定氧化应激激活PKC导致E-C偶联功能障碍的机制。这项应用的目的是确定过度氧化应激、PKC信号和心力衰竭的发展和进展之间的机制联系。我们将结合多学科方法，包括原位共聚焦成像、电生理学、分子生物学、病理小鼠模型和新型转基因小鼠模型来验证我们的假设。我们的研究成果将促进我们对心力衰竭病理生理学中氧化应激介导的PKC活化和T小管重构机制的认识，并有望为心力衰竭的治疗提供新的靶点，从而产生重要的积极影响。鉴于在过去十年中，退伍军人管理局医疗保健系统中用于治疗心力衰竭的资源数量稳步增长，既能改善患者预后又能降低与心力衰竭相关的护理成本的新疗法将为退伍军人管理局医疗保健系统带来重大好处。

 DESCRIPTION (provided by applicant): Heart failure is the number one reason for discharge for Veterans treated in VA health care system. Heart failure, measured at the organ level, is the result of cellular failure due to impairment of cardiac excitation-contraction (E-C) coupling. One key structural component of E-C coupling is the myocyte transverse (T)-tubule system. T-tubules play essential roles in membrane excitation, coordinated and synchronized activation of sarcoplasmic reticulum (SR) Ca2+ release, and muscle contraction. In failing myocytes from animal models and human patients, we and others have shown that the regularly arrayed T-tubule system undergoes disruptive remodeling, leading to aberrant intracellular Ca2+ release and compromised myocyte contractility. Our recently published data strongly suggest that T-tubule structural integrity is a critical structural determinant of myocardial contractile function. Moreover, we found that loss of protein expression of junctophilin-2 (JP2), a structural protein spanning T-tubules and the SR membrane, is a causative factor in T-tubule deformation in heart disease. Substantial evidence demonstrates that E-C coupling is impaired by oxidative stress, which is elevated in cardiomyocytes in heart disease. Despite the clear role for oxidative stress in cardiomyopathies, antioxidant trials in humans have failed to provide a therapeutic benefit, suggesting an incomplete understanding of oxidative stress-mediated pathways in heart disease or possibly wrong antioxidant strategy used in previous clinical trials. Previous reports have provided solid evidence that protein kinase C (PKC) is activated by oxidative stress. At the cellular level, PKC has been shown to impair E-C coupling. In pilot studies, activation of PKC resulted in alterations in cardiomyocyte structure and function. However, in order to identify new treatment strategies for heart disease that preserve cardiac contractility, there is a critical need to determine the mechanism by which PKC activation by oxidative stress induces E-C coupling dysfunction. The objective/goal of this application is to determine the mechanistic link between excessive oxidative stress, PKC signaling, and development and progression of heart failure. We will combine multidisciplinary approaches including in situ confocal imaging, electrophysiology, molecular biology, pathological mouse models and novel transgenic mouse models to test our hypothesis. Accomplishment of our studies will advance our understanding and provide new insights into the mechanisms of oxidative stress-mediated PKC activation and T-tubule remodeling in heart failure pathophysiology and is expected to have an important positive impact by revealing new targets for heart failure therapeutics. Given that over the last decade the number of resources used to treat heart failure within the VA health care system has grown steadily, new treatments that both improve patient outcomes and reduce the cost of care associated with heart failure will provide significant benefit to the VA health care system.