Interplay between mitophagy and substrate utilization in heart failure progression

项目摘要 线粒体功能障碍和线粒体代谢的改变与这种疾病的发展有关。 心力衰竭（HF）。线粒体自噬是一种特殊的自噬途径，介导溶酶体依赖的 清除受损的线粒体，并且对于线粒体质量控制至关重要。然而，我们目前 关于心脏中线粒体自噬及其如何与心肌代谢相关的知识是有限的。在正常 在某些条件下，心脏主要依赖于脂肪酸β-氧化（FAO）来为ATP的产生提供燃料。相比之下， 衰竭或肥大的心脏通常表现出受损的FAO和对葡萄糖利用的依赖性增加。尽管 尽管在理解削弱粮农组织的监管计划方面取得了重大进展，但目前尚不清楚如何转变 在心肌底物利用中的作用有助于线粒体自噬的调节。因此，本研究建议 着重于心肌基质利用改变时心肌线粒体自噬的功能意义 例如，在粮农组织受损的情况下。这个项目的目标是描绘小说 线粒体自噬和心肌基质利用之间的机制联系，以及确定 线粒体自噬是否代表了治疗心脏病的新机制和治疗靶点。 我们最近描述的mt-Keima小鼠模型将有助于这些研究，以监测体内心脏 线粒体自噬，以及一套创新的试剂，以遗传和免疫调节线粒体自噬 通量为了直接评估FAO在心脏中的作用，我们产生了心肌细胞特异性缺失的小鼠 CPT 2（CPT 2-cKO），编码FAO所需的单个基因。我们已经证明了线粒体自噬的减少 在FAO缺陷型心脏中，心功能受损的发展之前。我们的基因分析表明 心脏CPT 2缺失损害了PTEN诱导的推定激酶1（PINK 1）信号通路， 通过线粒体泛素化调节线粒体自噬。通过调节USP 30增强线粒体自噬， 它介导逆反应，线粒体上的去泛素化， 心脏缺陷因此，在拟议研究的目标1中，我们的目标是确定 心脏线粒体自噬对受损FAO的反应，以及剖析潜在的分子机制 将线粒体自噬与心肌基质利用联系起来。在拟议研究的目标2中，我们将从遗传学角度 使用缺乏USP 30的小鼠模型， 或用新型USP 30抑制剂治疗。我们将确定是否有害的心脏表型， 由心脏CPT 2缺失或压力超负荷引起的，可以通过恢复 通过抑制USP 30在心肌细胞中的线粒体自噬。完成拟议的研究将产生关键的 深入了解线粒体自噬在正常心血管生理学和病理条件下的作用，并将 从根本上推进了我们对线粒体代谢和 线粒体的质量控制。

PROJECT SUMMARY Mitochondrial dysfunction and altered mitochondrial metabolism have been implicated in the development of heart failure (HF). Mitophagy is a specialized autophagic pathway that mediates the lysosome-dependent clearance of damaged mitochondria, and is essential for mitochondrial quality control. However, our current knowledge regarding mitophagy in the heart and how it relates to myocardial metabolism is limited. Under normal conditions, the heart relies predominantly on fatty acid β-oxidation (FAO) to fuel ATP production. In contrast, a failing or hypertrophied heart usually shows impaired FAO and increased reliance on glucose utilization. Despite significant advancements in understanding the regulatory programs that attenuate FAO, it is unclear how shifts in myocardial substrate utilization contribute to the regulation of mitophagy. Therefore, this research proposal focuses on the functional significance of cardiac mitophagy in response to altered myocardial substrate utilization that occurs, for instance, in the setting of impaired FAO. The goal of this project is to delineate the novel mechanistic link between mitophagy and myocardial substrate utilization in the heart, as well as to determine whether mitophagy represents a novel mechanism and therapeutic target for the treatment of heart disease. These studies will be facilitated by our recently described mt-Keima mouse model to monitor in vivo cardiac mitophagy, as well as a set of innovative reagents to genetically and pharmacologically modulate mitophagic flux. To directly assess the role of FAO in the heart, we have generated mice with cardiomyocyte-specific deletion of CPT2 (CPT2-cKO), encoding a single gene required for FAO. We have demonstrated a decline in mitophagy precedes the development of impaired cardiac function in FAO-deficient hearts. Our genetic analyses suggest cardiac CPT2 deletion impairs the PTEN-induced putative kinase 1 (PINK1) signaling pathway, which positively regulates mitophagy through mitochondrial ubiquitination. Augmentation of mitophagy by modulating USP30, which mediates the reverse reaction, deubiquitination on mitochondria, mitigates the functional decline in FAO deficient hearts. Therefore, in Aim 1 of the proposed studies, our goal is to define the magnitude and Kinetics of cardiac mitophagy in response to impaired FAO, as well as to dissect the underlying molecular mechanisms connecting mitophagy to myocardial substrate utilization. In Aim 2 of the proposed studies, we will genetically and pharmacologically manipulate USP30 enzymatic function in the heart using mouse models that lack USP30 or are treated with a novel USP30 inhibitor. We will determine whether the detrimental cardiac phenotype, induced by cardiac CPT2 deletion or pressure overload, could be reversed, at least partially, by restoring mitophagy in cardiomyocytes via the inhibition of USP30. Completion of the proposed studies will produce critical insights into the role of mitophagy in normal cardiovascular physiology and in pathological conditions, and will fundamentally advance our understanding of the interaction between mitochondrial metabolism and mitochondrial quality control in the heart.