Autophagy-dependent cardioprotection in ischemia/reperfusion injury

 描述(由申请人提供)：在急性冠脉综合征中，迅速恢复缺血心脏的血流是至关重要的。然而，再灌注对心肌梗死面积也有显著影响(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，着眼于临床翻译。抑制1类组蛋白脱乙酰酶(HDAC)，特别是在再灌流时，在多种缺血/再灌注(I/R)损伤的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，抑制HDAC促进心肌细胞自噬，这对我们观察到的强大的心脏保护作用至关重要(3)。此外，适当的线粒体质量控制也是至关重要的 至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)抑制HDAC，b)细胞通透性多肽(TAT-Beclin)，一种强大的自噬激活剂(6)。前一种方法很快就可以转化为临床应用。后一种方法允许我们明确地分离激活的自噬的作用，将其从 HDAC抑制的其他作用。此外，我们将定义激活的自噬具有保护性的机制，重点是通过有缺陷的线粒体逃避自噬消除而过度产生ROS。我们假设Tat-Beclin治疗将促进自噬，并为再灌注损伤的心肌提供心脏保护。我们还假设，无论是用HDAC抑制或TAT-Beclin诱导自噬，都会导致再灌流期间交界区ROS产生减少，从而增加心肌细胞的存活率。目的1：确定TAT-Beclin对体外培养的I/R应激心肌细胞是否诱导自噬以及是否具有心肌保护作用。目的2：在活体心肌I/R损伤模型中确定TAT-Beclin是否具有心脏保护作用，以及自噬是否对心脏保护起重要作用。目的3：确定治疗性上调的心肌细胞自噬是否保留线粒体功能并减少ROS的产生。这一建议是及时的、机械性的、新颖的，并具有降低缺血性心脏病发病率和死亡率的巨大潜力。Tat-Beclin是一种选择性自噬诱导剂，是扩大我们对I/R损伤中依赖自噬的心肌保护的理解的有效途径。此外，我们将探索自噬途径中的心肌保护再灌注靶点，如ROS调节。由于Tat-Beclin是一种潜在的治疗剂，这是一种独特的翻译策略，具有潜在的临床影响。最后，这项研究为我完成内科科学家的培训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.