The Role of Mitochondrial Protein Acetylation in Left Ventricular Function

 描述（由申请人提供）：我想了解线粒体蛋白乙酰化在心力衰竭机制中的作用。在美国，心力衰竭是一个重大的疾病负担，超过一半的心力衰竭患者在诊断后5年内死亡。许多流行的心血管疾病，如缺血性、高血压和糖尿病性心肌病，无情地发展为心力衰竭。心力衰竭的潜在机制还不清楚，需要进一步研究。线粒体蛋白乙酰化是心血管疾病中重要的翻译后修饰，如糖尿病和缺血性心肌病。sirtuin 3（SIRT3）是sirtuin，主要负责调节线粒体中蛋白质的乙酰化状态。SIRT3是一种高度保守的NAD+依赖性线粒体脱乙酰酶。其靶点包括关键代谢酶，如参与脂肪酸代谢（长链酰基CoA脱氢酶或LCAD）、氧化磷酸化（ATP合酶）和葡萄糖代谢（丙酮酸脱氢酶或PDH）的酶等。我们最近已经表明，SIRT3在先天性肥厚型心肌病和心力衰竭，弗里德赖希共济失调（FRDA）心肌病模型中失活。结果是线粒体蛋白质的显著的超乙酰化。我们有新的证据表明，这些心脏的乙酰化与心脏功能恶化同时发生。FRDA是一种儿童期发病的常染色体隐性遗传疾病，可导致持续进行性神经源性和心源性功能障碍。心力衰竭是FRDA中最常见的死亡原因。我认为线粒体蛋白乙酰化过度通过抑制参与心脏代谢的关键酶的活性来损害心脏能量稳态，并且线粒体蛋白乙酰化失调有助于这种心力衰竭。我的项目提出通过操纵线粒体蛋白乙酰化和测量心脏细胞和生理功能的FRDA小鼠模型，作为肥厚型心肌病和心力衰竭的模型来测试这一假设。我将通过两种机制通过增加FXN消融心脏中的SIRT3活性来操纵乙酰化：目的我将测试增加SIRT3表达将改善肥厚型心肌病和心力衰竭的FRDA模型中的心脏功能的假设。我将在FRDA小鼠模型中使用SIRT3的遗传过表达。目的II将在肥厚型心肌病和心力衰竭的FRDA模型中验证增加线粒体中NAD+水平将刺激SIRT3活性并改善心脏功能的假设。我将使用NAD+前体增加这些FRDA小鼠中的NAD+水平。所有的老鼠和试剂都在手上。在我两年的提案结束时，我希望了解蛋白质乙酰化与FRDA心脏病之间的关系，并可能将SIRT3确定为治疗靶点。从长远来看，我的发现可能会进一步加深我们对心力衰竭和其他代谢性心血管疾病（如糖尿病、代谢综合征和缺血性心肌病）中乙酰化的理解。

 DESCRIPTION (provided by applicant): I want to understand the role that mitochondrial protein acetylation plays in the mechanism of heart failure. Heart failure carries a significant disease burden in the United States, with more than half of those with heart failure dying within 5 years of diagnosis. Many prevalent cardiovascular diseases, such as ischemic, hypertensive and diabetic cardiomyopathy, progress relentlessly to heart failure. The mechanisms underlying heart failure are not well understood and require further investigation. Mitochondrial protein acetylation is emerging as an important post-translational modification in cardiovascular diseases, such as that of diabetic and ischemic cardiomyopathy. Sirtuin 3 (SIRT3) is the sirtuin primarily responsible for regulating the acetylation state of proteins in the mitochondria. SIRT3 i a highly conserved NAD+ dependent mitochondrial deacetylase. Its targets include key metabolic enzymes, such as those involved in fatty acid metabolism (long chain acyl CoA dehydrogenase, or LCAD), oxidative phosphorylation (ATP synthase), and glucose metabolism (pyruvate dehydrogenase, or PDH), among others. We have recently shown that SIRT3 is inactivated in a model of congenital hypertrophic cardiomyopathy and heart failure, Friedreich's Ataxia (FRDA) cardiomyopathy. The result is marked hyperacetylation of mitochondrial proteins. We have new evidence that hyperacetylation in these hearts progresses concurrently with worsening heart function. FRDA is an autosomal recessive disease of childhood onset that results in relentlessly progressive neurogenic and cardiogenic dysfunction. Heart failure is the most common cause of death in FRDA. I believe that mitochondrial protein hyperacetylation damages cardiac energy homeostasis by inhibiting activity of key enzymes involved in heart metabolism, and that dysregulated mitochondrial protein acetylation contributes to this heart failure. My project proposes to test this hypothesis by manipulating mitochondrial protein acetylation and measuring cardiac cellular and physiologic function in a mouse model of FRDA, which serves as a model of hypertrophic cardiomyopathy and heart failure. I will manipulate acetylation by increasing SIRT3 activity in FXN-ablated hearts by two mechanisms: Aim I will test the hypothesis that increasing SIRT3 expression will improve heart function in the FRDA model of hypertrophic cardiomyopathy and heart failure. I will use genetic overexpression of SIRT3 in mouse models of FRDA. Aim II will test the hypothesis that increasing NAD+ levels in mitochondria will stimulate SIRT3 activity and improve heart function in the FRDA model of hypertrophic cardiomyopathy and heart failure. I will increase the level of NAD+ in these FRDA mice using a NAD+ precursor. All mice and reagents are in hand. At the end of my two-year proposal, I hope to understand the relationship between protein acetylation and the heart disease of FRDA, and possibly identify SIRT3 as a therapeutic target. My findings in the long term may further our understanding of heart failure and acetylation in other metabolic cardiovascular disease, such as diabetes, metabolic syndrome, and ischemic cardiomyopathy.