Autophagy-dependent cardioprotection in ischemia/reperfusion injury

 描述（由申请人提供）：快速恢复缺血心脏的血流在急性冠状动脉综合征中至关重要。然而，再灌注也显著影响心肌梗死面积（1）。目前，还没有针对再灌注损伤的临床治疗方法，迫切需要阐明再灌注损伤的机制-着眼于临床转化。抑制1类组蛋白脱乙酰酶（HDAC），特别是在再灌注时，在多种缺血/再灌注（I/R）损伤动物模型中提供心脏保护（2，3）。自噬在对I/R损伤的反应中至关重要（3）。我们已经证明，HDAC抑制促进心肌细胞自噬，这对我们观察到的强大心脏保护作用至关重要（3）。此外，适当的线粒体质量控制是至关重要的 I/R期间的心脏保护（4，5）。在这里，我们将定义心肌细胞自噬保护I/R损伤的机制。我们建议使用两种策略来操纵自噬：a）HDAC抑制，和B）细胞渗透性肽（Tat-Beclin），一种强自噬激活剂（6）。前一种方法可以立即转化为临床背景。后一种方法使我们能够专门分离激活的自噬的贡献，从 HDAC抑制的其他作用。此外，我们将定义机制，激活自噬是保护性的，重点是过量的ROS生产缺陷线粒体逃避自噬消除。 我们假设Tat-Beclin治疗将促进自噬并对再灌注损伤的心肌提供心脏保护。我们还假设，HDAC抑制或Tat-Beclin诱导自噬将导致边缘区再灌注期间ROS产生减少，从而增加心肌细胞存活。目的1：确定Tat-Beclin是否诱导自噬以及它是否在体外I/R应激心肌细胞中具有心脏保护作用。目标二：确定Tat-Beclin是否在体内心脏I/R损伤模型中具有心脏保护作用，以及自噬是否是心脏保护所必需的。目的3：确定治疗上调的心肌细胞自噬是否保留线粒体功能并减少ROS产生。 这一建议是及时的，机械的，新颖的，并具有很大的潜力，以减少缺血性心脏病的发病率和死亡率。Tat-Beclin是一种选择性自噬诱导剂，它是扩展我们对I/R损伤中自噬依赖性心脏保护作用的理解的有力途径。此外，我们将探讨自噬途径中的心脏保护性再灌注靶点，如ROS调节。由于Tat-Beclin是一种潜在的治疗剂，因此这是一种具有临床影响潜力的独特翻译策略。最后，这项研究为我完成作为一名医生科学家的训练提供了一个重要的平台。

 DESCRIPTION (provided by applicant): Rapid restoration of blood flow to the ischemic heart is vital in acute coronary syndromes. However, reperfusion also contributes significantly to myocardial infarct size(1). Currently, there are no clinical therapies targeting reperfusion injury Elucidation of mechanisms of reperfusion injury -- with an eye toward clinical translation -- is urgently needed. Inhibition of class 1 histone deacetylases (HDACs), specifically at the time of reperfusion, confers cardioprotection in multiple animal models of ischemia/reperfusion (I/R) injury(2, 3). Autophagy is critical in the response to I/R injury(3). We have demonstrated that HDAC inhibition promotes cardiomyocyte autophagy, which is critical to the robust cardioprotective effects we observe(3). Also, appropriate mitochondrial quality control is critical to cardioprotection during I/R(4, 5). Here, we will define mechanisms whereby cardiomyocyte autophagy protects against I/R injury. We propose to manipulate autophagy using two strategies: a) HDAC inhibition, and b) a cell-permeable peptide (Tat-Beclin), a strong autophagy activator(6). The former approach is imminently translatable to the clinical context. The latter approach allows us to isolate specifically the contribution of activated autophagy, parsing it from other effects of HDAC inhibition. Also, we will define mechanisms whereby activated autophagy is protective, focusing on excessive ROS production by defective mitochondria escaping autophagic elimination. We hypothesize that Tat-Beclin treatment will promote autophagy and confer cardioprotection to reperfusion-injured myocardium. We also hypothesize that induction of autophagy either with HDAC inhibition or Tat-Beclin will lead to a decrease in ROS production during reperfusion in the border zone resulting in increased cardiomyocyte survival. Aim 1: Determine whether Tat-Beclin induces autophagy and whether it is cardioprotective in I/R- stressed cardiomyocytes in vitro. Aim 2: Determine whether Tat-Beclin is cardioprotective in an in vivo cardiac I/R injury model and whether autophagy is essential for the cardioprotection. Aim 3: Determine whether therapeutically up-regulated cardiomyocyte autophagy preserves mitochondrial function and reduces ROS production. This proposal is timely, mechanistic, novel, and holds great potential to reduce morbidity and mortality in ischemic heart disease. Tat-Beclin, a selective autophagy inducer, is a powerful way to extend our understanding of autophagy-dependent cardioprotection in I/R injury. Further, we will explore cardioprotective reperfusion targets in the autophagic pathway, such as ROS regulation. As Tat-Beclin is a potential therapeutic agent, this is a uniquely translational strategy with potential for clinical impact. Finally, this research serves as a critical platform for me to complete my training as a physician-scientist.