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 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 重塑，先于心衰进展而发生的结构重塑。在HF过程中，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。网络的影响 全身和心脏特异性支链氨基酸异常对心力衰竭发病机制的影响仍很大程度上是未知的。使用动物 通过建立HF模型，我们发现HF本身会损害肝脏的支链氨基酸代谢，这可能解释了 循环中支链氨基酸和支链氨基酸增加。此外，我们发现，与之前的报告相反，有 心脏BCAA进入TCA循环的情况可以忽略不计(即复苏)。相反，心脏倾向于挽救 通过将BCKA转换为BCAA，形成BCAA池。综上所述，这些发现表明， 心脏和肝脏之间的代谢相互作用，增加BCAA和BCKA向衰竭心脏的输送。 此外，心脏支链氨基酸的代谢似乎会影响其他底物的代谢，如葡萄糖 和脂肪酸。我们最近发现，在肝脏中，控制支链氨基酸代谢的调节酶 在线粒体中，还调节一种协调葡萄糖和脂肪新陈代谢的胞浆酶。它是 尚不清楚这个新的代谢调节节点是否在心力衰竭中起作用。本应用程序的总体目标是 是为了确定失调的全身和心脏特异性支链氨基酸代谢在结构和功能上的作用 心衰时的代谢重塑。我们的具体目标是：(1)确定肝脏和心脏的失调 心力衰竭时支链氨基酸代谢参与心力衰竭的发病；(2)确定心力衰竭的调控系统是否 心脏支链氨基酸代谢也影响衰竭心脏的燃料偏好。为了实现目标1，我们将 产生肝脏和心脏特异的基因敲除小鼠，促进肝脏或心脏支链氨基酸的分解代谢， 分别进行了分析。然后我们将在这些动物中诱导心衰，并将表征功能和分子 心脏的变化，以确定支链氨基酸代谢的器官特异性变化如何影响心衰进展。 为了达到目标2，我们将使用最先进的代谢流技术从这些心脏中分离跳动的心脏 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建确定新的机制基础。 总之，这些实验将使我在以下技能的基础上发展：1)基础生化、分子和 代谢研究技术；2)心脏病动物模型的建立和利用；3) 心脏代谢和生理表型。在此授权期内收集的数据与 来自基础代谢和翻译代谢研究领域的领导者的指导将使我做好准备，以完成我的 成为心脏代谢性疾病领域的独立内科医生兼科学家的长期目标。

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.