NMR of Mitochondrial Transporters in Cardiac Hypertrophy

描述(由申请人提供)：这项建议利用了我们最近的发现，在先前资助的时期，在肥厚的心肌中，转运蛋白介导的代谢途径被补偿激活，以对抗长链游离脂肪酸(LCFA)氧化和有限的丙酮酸脱氢酶(PDH)活性的降低。我们发现，在压力超负荷、肥厚率高的心脏中，LCFA氧化和TCA循环通量速率之间存在不匹配，这种心脏不能通过PDH增加葡萄糖氧化来补偿。相反，通过增加进入TCA循环第二个跨度的无性通量来进行葡萄糖氧化的替代方法是显而易见的，同样是为了补充TCA循环而加速的胞液中间体交换机制。我们假设，在压力超负荷肥厚的代偿阶段，重新招募替代途径来支持TCA循环，是支持氧化能量产生的适应性的、但效率较低的机制。总体目标是通过药理学和基因组操作对发生在大鼠心脏代偿性和后期失代偿性肥大期间的代谢适应进行干预。我们的实验目标将1)通过药物增强PDH时丙酮酸进入TCA循环来探索这种中间代谢适应性变化的能量含义；2)阐明OMC活性增加与肥厚心脏由于糖酵解速率与葡萄糖氧化解偶联而减轻胞液氧化还原负荷之间的联系；3)利用我们在体内心脏特异性基因转移效率方面的最新进展，阐明OMC通过诱导肥厚心脏OMC过度表达和OMC减少来提供TCA循环中间产物的调节作用；4)结合~(13)C核磁共振和心脏MRI显微镜，通过探索肥厚和扩张心脏之间的潜在区别，来研究代谢适应和室壁应变之间的联系。新颖的实验探索了特定的向心性肥厚(蛋白激酶Cβ过度表达)和扩张型心肌病(PKC epsilon过度表达)小鼠模型之间的代谢差异，我们预计这种模型将在整个左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性机制，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.