Investigating the novel role of acetylation in cardiac mitochondrial bioenergetics and function in the aging heart

心肌线粒体功能障碍是衰老和许多衰老相关疾病发病机制的核心。 线粒体通过氧化燃料为心脏收缩功能提供生物能量能力 底物和对该系统的完全控制对于维持心脏效率是不可或缺的。具体来说， 羟基辅酶A脱氢酶(HADHA)和长链酰辅酶A脱氢酶(LCAD)在细胞周期中的作用 在心脏中催化长链脂肪酸的氧化已经得到了很好的研究，它们的功能障碍也是相关的 减少脂肪酸氧化(FAO)和心脏能量消耗。然而，研究的重点是 了解调节这些关键线粒体能量底物酶的细胞机制 老化的心脏是稀有的。在最近的一项研究中，我们描述了增加乙酰化增加了酶的活性 LCAD和HADHA在饮食诱导肥胖中的作用及其与线粒体表达变化的关系 乙酰基转移酶GCN5L1和脱乙酰基酶SIRT3。在老化的心脏中，我们观察到GCN5L1和 降低SIRT3表达导致HADHA和LCAD乙酰化状态增加。基于 这些观察结果，我们假设GCN5L1和SIRT3控制HADHA和LCAD乙酰化，并且 衰老过程中这一机制的失调导致线粒体生物能量学和 心肌细胞能量耗竭。为了验证我们的中心假设，我们提出了以下目标：1.我们将 乙酰化对幼年、中年和老年小鼠HADHA和LCAD活性的调节作用 红心。使用基于高分辨率质谱学的蛋白质组学；我们将确定乙酰化位点，相对 量化和评估它们在关键生物学过程和酶功能中的影响。2.我们会 中青年HADHA和LCAD活性调节机制的研究 和老老鼠的心。我们将使用新的GCN5L1和SIRT3心脏KO动物来描绘分子 衰老过程中HADHA和LCAD乙酰化变化的机制。3.我们会调查如何 脂肪酸氧化蛋白乙酰化改变对线粒体生物能量学和心肌收缩的影响 在老化的心脏中起作用。这项研究的长期目标是了解心脏的调节作用 人类衰老和老年相关疾病中的线粒体乙酰化。我们的结果将提高我们的理解 乙酰化介导的FAO酶在衰老线粒体生物学中的调节并提供新的见解 衰老心脏中燃料底物使用的调节及其对改善线粒体的作用 心功能随年龄增长。

Cardiac mitochondrial dysfunction is central to the pathogenesis of aging and many age related diseases. Mitochondria supply the bioenergetic capacity for cardiac contractile function through oxidation of fuel substrates and a complete control of this system is indispensable to maintain cardiac efficiency. Specifically, the role of Hydroxyacyl-CoA Dehydrogenase (HADHA) and Long Chain Acyl-CoA Dehydrogenase (LCAD) in catalyzing the oxidation of long chain fatty acids in the heart is well studied and their dysfunction is associated with decreased fatty acid oxidation (FAO) and cardiac energy depletion. However, studies focused on understanding the cellular mechanisms that regulate these key mitochondrial energy substrate enzymes in the aging heart are scarce. In a recent study, we described that increased acetylation increases the activities of LCAD and HADHA in diet induced obesity, which was mediated by changes in the expression of mitochondrial acetyltransferase GCN5L1 and deacetylase SIRT3. In the aging heart, we observe increased GCN5L1 and decreased SIRT3 expression resulting in an increased acetylation status of HADHA and LCAD. Based on these observations, we hypothesize that GCN5L1 and SIRT3 control HADHA and LCAD acetylation, and that dysregulation of this mechanism in aging contributes to reduced mitochondrial bioenergetics and cardiomyocyte energy depletion. To test our central hypothesis, we propose the following aims: 1. We will investigate how acetylation regulates the activity of HADHA and LCAD in young, middle aged and old mouse hearts. Using high resolution mass spectrometry based proteomics; we will identify acetylation sites, relative quantification and assess their impact in key biological processes and enzymatic functions. 2. We will investigate the mechanisms associated with regulation of HADHA and LCAD activity in young, middle aged and old mouse hearts. We will use novel GCN5L1 and SIRT3 cardiac KO animal to delineate the molecular mechanisms underlying changes in HADHA and LCAD acetylation in aging process. 3. We will investigate how changes in fatty acid oxidation protein acetylation impacts mitochondrial bioenergetics and cardiac contractile function in aging heart. The long term goal of this study is to understand the regulatory role of cardiac mitochondrial acetylation in human aging and age related diseases. Our results will improve our understanding of acetylation mediated regulation of FAO enzymes in aging mitochondrial biology and provide novel insights on regulation of fuel substrate usage in the aging heart and their contribution towards improving mitochondrial and cardiac function with age.