MITOCHONDRIAL DYSFUNCTION IN DIABETIC CARDIOMYOPATHY

糖尿病心肌病中的线粒体功能障碍

• 批准号: 8364979
• 负责人: Kenneth M Humphries
• 金额: $ 16.04万
• 依托单位: OKLAHOMA MEDICAL RESEARCH FOUNDATION
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-05-01 至 2012-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8364979
• 关键词: Attenuated; Biochemical; Bioenergetics; Biology; Blood Vessels; Carbon; Cardiac; Cause of Death; Cell Culture Techniques; Coupled; Cyclic AMP-Dependent Protein Kinases; Diabetes Mellitus; Disease; Disease Progression; Energy-Generating Resources; Fatty Acids; Free Radicals; Funding; Genetic Models; Glycolysis; Goals; Grant; Heart; Hyperglycemia; Insulin; Insulin-Dependent Diabetes Mellitus; Interdisciplinary Study; Lead; Link; Magnetic Resonance Imaging; Metabolic; Metabolic stress; Mitochondria; Molecular; Mus; National Center for Research Resources; Nonesterified Fatty Acids; Oxidative Phosphorylation; Oxidative Stress; Play; Pliability; Principal Investigator; Production; Protein Biochemistry; Protein Kinase; Proteins; Proteomics; Relative (related person); Reliance; Research; Research Infrastructure; Resources; Role; Signal Transduction; Source; Structure; Supplementation; Testing; United States National Institutes of Health; base; cost; diabetic; diabetic cardiomyopathy; fatty acid oxidation; mitochondrial dysfunction; oxidation; respiratory

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Diabetic cardiomyopathy is a leading cause of death among diabetics. Mechanistically, loss of mitochondrial function likely plays a role in the progression of the disease due to bioenergetic deficits and increased free radical production. Oxidative stress can be further exacerbated by metabolic conditions that result from diabetes. For example, elevated free fatty acids inhibit glycolysis and mitochondrial oxidative phosphorylation by non fatty acid carbon sources (Randle cycle). A constant, rigid, utilization of fatty acids may promote sustained increased free radical production during hyperglycemic conditions because fatty acid oxidation generates more free radicals relative to other oxidizable substrates. Importantly, the Randle cycle may be disrupted by activation of cAMP-dependent protein kinase (PKA), suggesting endogenous means of alleviating metabolic stress that are present may be compromised. Using a genetic model of type 1 diabetes (OVE26 mice), we have begun examining the longitudinal effects of the disease on cardiac mitochondria and PKA signaling. Our results indicate a rigid reliance of cardiac mitochondria from OVE26 mice on fatty acid oxidation for supporting energy production. Importantly, we have also found that PKA protein levels and activity are decreased in hearts of OVE26 mice. Based on these observations we hypothesize: Under hyperglycemic conditions, mitochondrial reliance on fatty acid oxidation increases oxidative stress. Reliance on fatty acids as an energy source is exacerbated by oxidative inactivation and loss of PKA signaling. Prolonged oxidative stress, coupled with loss of PKA activity, contributes to diabetic cardiomyopathy. This hypothesis will be tested using a genetic model of type 1 diabetes (OVE26 mice), cell culture, and protein biochemistry by the following specific aims. Aim 1. Mechanistically determine the alterations in mitochondrial function that occur with the progression of diabetic cardiomyopathy. The hypothesis is that increased oxidative stress associated with hyperglycemia is a function, in part, of rigid utilization of fatty acids with concomitant decreases respiratory activity. Biochemical studies, proteomic analysis, and cardiac structure/function analysis using MRI will be performed to test this hypothesis. Aim 2. Define the molecular mechanisms that lead to deficits in PKA activity and content as induced by hyperglycemia. We hypothesize that the increased oxidative stress promotes PKA oxidation, inactivation, and degradation. This loss of PKA activity then contributes to further oxidative stress via sustained and rigid utilization of fatty acid oxidation. Aim 3. The goal of this aim is to define the causal link between decreased PKA signaling, diminished mitochondrial function, increased oxidative stress, and diabetic cardiomyopathy. Studies will be performed to determine how insulin supplementation or activation of PKA restores metabolic pliability. It is hypothesized that sustaining PKA signaling will sustain mitochondrial function and attenuate the progression of diabetic cardiomyopathy.

该子项目是利用资源的众多研究子项目之一 由 NIH/NCRR 资助的中心拨款提供。子项目的主要支持 并且子项目的主要研究者可能是由其他来源提供的， 包括其他 NIH 来源。 子项目可能列出的总成本 代表子项目使用的中心基础设施的估计数量， NCRR 赠款不直接向子项目或子项目工作人员提供资金。 糖尿病心肌病是糖尿病患者死亡的主要原因。从机制上讲，由于生物能缺陷和自由基产生增加，线粒体功能丧失可能在疾病进展中发挥作用。 糖尿病引起的代谢状况可能会进一步加剧氧化应激。 例如，游离脂肪酸升高会抑制非脂肪酸碳源的糖酵解和线粒体氧化磷酸化（兰德尔循环）。脂肪酸的持续、严格的利用可以促进高血糖条件下自由基产生的持续增加，因为相对于其他可氧化底物，脂肪酸氧化会产生更多的自由基。 重要的是，Randle 循环可能会因 cAMP 依赖性蛋白激酶 (PKA) 的激活而受到干扰，这表明缓解代谢应激的内源性手段可能会受到损害。 使用 1 型糖尿病的遗传模型（OVE26 小鼠），我们开始研究该疾病对心脏线粒体和 PKA 信号传导的纵向影响。 我们的结果表明 OVE26 小鼠的心脏线粒体严格依赖脂肪酸氧化来支持能量产生。重要的是，我们还发现 OVE26 小鼠心脏中的 PKA 蛋白水平和活性降低。基于这些观察，我们假设：在高血糖条件下，线粒体对脂肪酸氧化的依赖会增加氧化应激。 氧化失活和 PKA 信号传导丧失加剧了对脂肪酸作为能源的依赖。 长时间的氧化应激，加上 PKA 活性的丧失，会导致糖尿病性心肌病。 该假设将通过 1 型糖尿病遗传模型（OVE26 小鼠）、细胞培养和蛋白质生物化学通过以下具体目标进行测试。 目标 1. 从机制上确定随着糖尿病心肌病进展而发生的线粒体功能的改变。 假设认为，与高血糖相关的氧化应激增加在一定程度上是脂肪酸的严格利用以及随之而来的呼吸活动减少的一个功能。 将使用 MRI 进行生化研究、蛋白质组分析和心脏结构/功能分析来检验这一假设。 目标 2. 定义导致高血糖引起的 PKA 活性和含量缺陷的分子机制。我们假设氧化应激增加会促进 PKA 氧化、失活和降解。 PKA 活性的丧失会通过持续且严格地利用脂肪酸氧化而导致进一步的氧化应激。目标 3。该目标的目的是确定 PKA 信号传导减弱、线粒体功能减弱、氧化应激增加和糖尿病心肌病之间的因果关系。 将进行研究以确定补充胰岛素或激活 PKA 如何恢复代谢柔韧性。 据推测，维持 PKA 信号传导将维持线粒体功能并减轻糖尿病心肌病的进展。