Enhancing Autophagy and Mitochondrial Biogenesis to Mitigate Cardiac Reperfusion Injury

项目摘要：在再灌流性心肌梗死(MI)中，大约50%的细胞死亡是由于 再灌注损伤，目前仍缺乏临床治疗方法。迫切需要填补这一知识空白，并 为此开发新的治疗方法。最初适当的线粒体质量控制是心脏保护的关键 缺血/再灌注(I/R)后。线粒体的动态平衡受到两个过程的严格调控：有丝分裂 (自噬对受损线粒体的降解)和线粒体的生物发生。自噬，一种 细胞成分循环(包括线粒体)所需的进化保守过程受损 在I/R期间，线粒体的生物发生部分受过氧化物酶体增殖物激活受体γ的调节 辅活化子-1α(Pgc1)。重要的是，肾脏I/R损伤不会增加线粒体的生物生成 和脑，尽管有pGc1的诱导。这些结果表明，受损的自噬/有丝分裂吞噬 随后的I/R有助于线粒体生物发生的减弱。增强自噬和 因此，在I/R期间同时进行线粒体生物发生可以恢复线粒体的动态平衡。 与此一致的是，我们未发表的数据显示，Tat-Beclin多肽在 再灌流时间可缩小小鼠脑梗塞面积，增加Pgc1表达和线粒体 生物发生(依赖于自噬)。同样，自噬时的药物激活 再灌流(使用FDA批准的HDAC抑制剂SAHA)诱导自噬和前列环素，并减少 梗塞面积&40%。此外，SAHA+Pgc1的过表达进一步增加了线粒体的生物发生。 在大脑中的研究已经确定帕金和帕里斯是前列环素表达的调节者。学习 帕金森氏症、小鼠模型和增强帕金森活性的小分子都是可用的。 假设：在I/R期间激活自噬通过联合移除 损伤的线粒体和随后通过依赖Pgc1的线粒体生物发生进行的替换 以Parkin-Paris依赖的方式，加强这两个过程将提供更有效的心脏保护。 目的1.确定自噬是否是线粒体生物发生的必要条件和充分条件 在基础状态和心脏I/R期间。 目的2.明确I/R期间自噬介导的线粒体生物发生和心肌保护作用 依赖于PARKIN-PARIS-PGC_1信号轴。 目的3.确定自噬/有丝分裂吞噬和线粒体是否同时增强 心脏I/R期间的生物发生将增强心脏保护。 意义和新颖性。这项研究将确定自噬和前列环素依赖的线粒体 生物发生在再灌注损伤中起着关键作用。临床上，诱导自噬和线粒体生物发生 再灌注在药学上是可行的，这可能导致治疗再灌注损伤的新方法。 1

PROJECT SUMMARY: In reperfused myocardial infarction (MI), approximately 50% of cell death is due to reperfusion injury, which still lacks clinical therapies. There is an urgent need to fill in this knowledge gap and to develop novel therapies for this. Initial appropriate mitochondrial quality control is critical for cardioprotection following ischemia/reperfusion (I/R). Mitochondrial homeostasis is tightly regulated by two processes: mitophagy (degradation of damaged mitochondria by autophagy) and mitochondrial biogenesis. Autophagy, an evolutionarily conserved process required for cellular constituent recycling (including mitochondria), is impaired during I/R. Mitochondrial biogenesis is regulated in part by peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC1). Importantly, mitochondria biogenesis is not increased by I/R injury in the kidney and brain, despite induction of PGC1. These results suggest that impaired autophagy/mitophagy following I/R contributes to the attenuation of mitochondrial biogenesis. Enhancing autophagy and mitochondrial biogenesis simultaneously during I/R may therefore restore mitochondrial homeostasis. Consistent with this, our unpublished data show that specific induction of autophagy with Tat-Beclin peptide at the time of reperfusion reduces infarct size in mice, and augments PGC1 expression and mitochondrial biogenesis (dependent on the autophagy). Similarly, pharmacological activation of autophagy at the time of reperfusion (using the FDA-approved HDAC inhibitor, SAHA) induces autophagy and PGC1 and reduces infarct size >40%. Moreover, SAHA plus PGC1 overexpression further increased mitochondrial biogenesis. Studies in the brain have identified Parkin and PARIS as the regulator of PGC1 expression. To study Parkinson’s disease, mouse models, and small molecules enhancing Parkin activity are available. Hypothesis: Activation of autophagy confers cardioprotection during I/R through the combined removal of damaged mitochondria and subsequent replacement via PGC1-dependent mitochondrial biogenesis, in a Parkin-PARIS dependent manner, and enhancing both processes will afford more effective cardioprotection. Aim 1. To determine whether autophagy is both necessary and sufficient for mitochondrial biogenesis under basal conditions and during cardiac I/R. Aim 2. To define whether autophagy-mediated mitochondrial biogenesis and cardioprotection during I/R are dependent on the Parkin-PARIS-PGC1 signaling axis. Aim 3. To establish whether simultaneous enhancement of autophagy/mitophagy and mitochondrial biogenesis during cardiac I/R will augment cardioprotection. Significance and novelty. This study will determine whether autophagy and PGC1-dependent mitochondrial biogenesis is critical for reperfusion injury. Clinically, inducing autophagy and mitochondrial biogenesis during the reperfusion is pharmaceutically feasible, which may lead to novel therapies for reperfusion injury. 1