NMR of Mitochondrial Transporters in Cardiac Hypertrophy

描述（由申请方提供）：该提案利用了我们在先前资助期间的最新发现，即肥厚心肌中转运蛋白介导的代谢途径的代偿性激活，以对抗长链游离脂肪酸（LCFA）氧化速率降低和丙酮酸脱氢酶（PDH）活性受限。我们已经确定了在压力超负荷、肥厚性心率心脏中LCFA氧化和TCA循环通量率之间的不匹配，其不能通过PDH增加葡萄糖氧化来补偿。相反，葡萄糖氧化的替代手段通过增加回补通量进入TCA循环的第二个跨度是明显的，作为细胞溶质中间体的加速交换机制，以补充TCA循环。我们假设，招聘替代途径，以燃料的TCA循环在代偿期的压力超负荷肥大的适应性，但效率较低的机制，支持氧化能量的生产。总体目标是通过药理学和基因组学操作干预大鼠心脏代偿性和后期失代偿性肥大期间发生的代谢适应。我们的实验目的是：1）通过在PDH时增加丙酮酸进入TCA循环，探索这种中间代谢适应性变化的能量意义; 2）阐明OMC活性增加（一种将细胞溶质还原当量转移到线粒体中的蛋白质）与肥厚心脏中糖酵解速率与葡萄糖氧化解解偶联引起的细胞溶质氧化还原负荷减轻之间的联系; 3）利用我们在心脏特异性体内基因转移效率方面的新进展，阐明OMC在肥厚心脏中通过诱导OMC过表达和OMC减少提供TCA循环中间体中的调节作用; 4）联合收割机结合13 C NMR和心脏MRI显微镜，通过探索肥厚和扩张心脏之间的潜在区别，研究代谢适应和壁应变之间的联系。新的实验探索了向心性肥大（蛋白激酶C β过表达）与扩张型心肌病（PKC β过表达）的特定小鼠模型之间的代谢差异，我们预计这将在左心室壁显示不同的应变曲线。这项研究将确定降低能量生产效率的适应机制，并可能导致心力衰竭的进展。

DESCRIPTION (provided by applicant): This proposal exploits our recent findings, during the previously funded period, of compensatory activation of transporter mediated metabolic pathways in the hypertrophied myocardium that counter reduced rates of long chain free fatty acid (LCFA) oxidation and limited pyruvate dehydrogenase (PDH) activity. We have identified a mismatch between LCFA oxidation and TCA cycle flux rates in the pressure overloaded, hypertrophic rate heart that is not compensated by increased glucose oxidation via PDH. Rather, alternative means of glucose oxidation via increased anaplerotic flux into the second span of the TCA cycle are in evidence, as are accelerated exchange mechanisms for cytosolic intermediates to supplement the TCA cycle. We hypothesize that recruitment of alternative pathways to fuel the TCA cycle in the compensatory phase of pressure overload hypertrophy represent adaptive, yet less efficient mechanisms for supporting oxidative energy production. The overall goal is to intervene via pharmacologic and genomic manipulation of the metabolic adaptations that occur during compensated and later stage, decompensated hypertrophy in rat hearts. Our experimental aims will 1) explore the energetic implications of such adaptive changes in intermediary metabolism by pharmacologically augmenting pyruvate entry into the TCA cycle at PDH; 2) elucidate the link between increased OMC activity, a protein transferring cytosolic reducing equivalents into the mitochondria, and alleviation of the cytosolic redox load due to uncoupling of glycolytic rate from glucose oxidation in the hypertrophic heart; 3) exploit our newly developed advances in the efficiency of cardiac-specific in vivo gene transfer to elucidate the regulatory role of OMC in providing TCA cycle intermediates via induced OMC overexpression and OMC reductions in hypertrophic hearts; 4) combine 13C NMR and cardiac MRI microscopy to investigate the link between metabolic adaptations and wall strain by exploring potential distinctions between hypertrophic and dilated hearts. Novel experiments explore the metabolic distinctions between specific murine mouse models of concentric hypertrophy (protein kinase C beta overexpression) versus dilated cardiomyopathy (PKC epsilon overexpression) which we anticipate will display distinct strain profiles across the left ventricular wall. The research will define adaptive mechanisms that reduce energy production efficiency and may contribute to the progression toward heart failure.