The Branched Chain Ketoacid Dehydrogenase Kinase-Phosphatase System as a New Regulatory Node in Mycocardial Fuel Section

尽管在过去的几十年里取得了重大的治疗进展，但心力衰竭（HF）发作后的死亡率仍然很高。 症状仍然非常严重。心脏代谢途径的变化，这一过程称为代谢 重构，先于HF进展时发生的结构重构。HF期间，支链 氨基酸（BCAA）和支链酮酸（BCKA）在循环中增加。此外，心脏 BCAA代谢途径受损，导致心脏BCAA和BCKA增加。的影响 全身性和心脏特异性BCAA失调对HF发病机制的影响在很大程度上仍然未知。使用动物 在HF模型中，我们发现HF本身损害肝脏BCAA代谢，这可能解释了HF对肝脏BCAA代谢的影响。 增加循环BCAA和BCKA。此外，我们发现，与以往的报告相比， 心脏BCAA进入TCA循环（即回补）可忽略不计。相反，心脏倾向于挽救 BCAA池通过BCKA转化为BCAA。总的来说，这些发现表明， 心脏和肝脏之间的代谢相互作用，增加了BCAA和BCKA向衰竭心脏的输送。 此外，心脏BCAA代谢似乎影响其他底物如葡萄糖的代谢 和脂肪酸。我们最近在肝脏中发现，控制支链氨基酸代谢的调节酶 在线粒体中，还调节协调葡萄糖和脂质代谢的胞质酶。是 尚不清楚这种新的代谢调节节点是否在HF中起作用。本申请的总体目标 是为了确定失调的全身性和心脏特异性BCAA代谢在结构和 HF中的代谢重塑。我们的具体目标是：（1）确定肝脏和心脏的调节异常如何影响心脏功能。 HF期间BCAA代谢有助于HF发病机制;（2）为了确定BCAA代谢的调节系统是否与HF的发病机制有关， 心脏BCAA代谢也影响衰竭心脏的燃料偏好。为了实现目标1，我们将 产生促进肝脏或心脏BCAA催化剂的肝脏和心脏特异性敲除小鼠， 分别然后，我们将在这些动物中诱导HF，并将表征HF的功能和分子生物学特性。 心脏的变化，以确定BCAA代谢的器官特异性改变如何影响HF进展。 为了实现目标2，我们将使用最先进的代谢通量技术，在离体跳动的心脏，从这些 动物，以确定基因操作如何影响心脏燃料的使用。如果成功，这些研究将 为衰竭心脏的结构和代谢重塑定义新的机制基础。 总之，这些实验将使我建立在以下技能：1）基本的生物化学，分子和 代谢研究技术; 2）心脏病动物模型的产生和利用;和3） 心脏代谢和生理表型。在此颁奖期间收集的数据加上 来自基础和转化代谢研究领域的领导者的指导将使我做好准备，以实现我的目标。 长期目标是成为心脏代谢疾病领域的独立医生-科学家。

Despite major treatment advances over the last decades, mortality after the onset of heart failure (HF) symptoms remains extremely high. Changes in cardiac metabolic pathways, a process termed metabolic remodeling, precedes the structural remodeling that occurs with HF progression. During HF, branched-chain amino acids (BCAA) and branched-chain ketoacids (BCKA) increase in circulation. Moreover, the cardiac BCAA metabolic pathway becomes impaired, leading to increased cardiac BCAA and BCKA. The impact of systemic and cardiac-specific BCAA dysregulation on HF pathogenesis is still largely unknown. Using animal models of HF, we have found that HF per se impairs hepatic BCAA metabolism, which may explain the increase in circulating BCAA and BCKA. Additionally, we have found that, in contrast to previous reports, there is negligible entry of cardiac BCAA into the TCA cycle (i.e. anaplerosis). Rather, the heart tends to salvage the BCAA pool through conversion of BCKA into BCAA. Taken together, these findings suggest an unappreciated metabolic interplay between the heart and liver that increases delivery of BCAA and BCKA to the failing heart. Moreover, cardiac BCAA metabolism appears to affect the metabolism of other substrates such as glucose and fatty acids. We recently discovered, in the liver, that the regulatory enzymes that control BCAA metabolism in the mitochondria also regulate a cytosolic enzyme that coordinates glucose and lipid metabolism. It is unknown whether this new metabolic regulatory node has a role in HF. The overall objective of this application is to determine the role of dysregulated systemic and cardiac-specific BCAA metabolism in structural and metabolic remodeling in HF. Our specific aims are (1) To determine how dysregulation of hepatic and cardiac BCAA metabolism during HF contributes to HF pathogenesis and (2) To determine if the regulatory system of cardiac BCAA metabolism also influences fuel preference in the failing heart. To achieve Aim 1, we will generate liver- and heart-specific knockout mice that promote hepatic or cardiac BCAA catabolism, respectively. We will then induce HF in these animals and will characterize the functional and molecular changes in the heart to determine how organ-specific alterations in BCAA metabolism affect HF progression. To achieve Aim 2, we will use state-of-the art metabolic flux techniques in isolated beating hearts from these animals to determine how the genetic manipulations affect cardiac fuel use. If successful, these studies will define new mechanistic bases for structural and metabolic remodeling in the failing heart. Together, these experiments will allow me to build on the following skills: 1) basic biochemical, molecular and metabolic research techniques; 2) generation and utilization of animal models of cardiac disease; and 3) cardiac metabolic and physiological phenotyping. The data gathered during this award period coupled with mentorship from leaders in the fields of basic and translational metabolism research will prepare me to fulfill my long-term goal of becoming an independent physician-scientist in the field of cardiometabolic disease.