Mechanisms connecting dysregulated BCAA, glucose & lipid metabolism in the pathogenesis of metabolic disease

.项目概要-R 01 Newgard/赫尔曼。 我们小组进行的研究帮助确定了支链氨基酸（BCAA）及相关物质 代谢产物与胰岛素抵抗和T2 D相关，可预测糖尿病的发展和干预 结果，并高度响应治疗干预。本提案的目的是充分了解 BCAA、葡萄糖和脂质代谢协同失调的代谢和分子机制。 当我们改变支链酮酸脱氢酶时， （BCKDH）复合物活性，通过药理学和分子操作其调节激酶（BDK）， 磷酸酶（PPM 1 K）在肥胖和代谢性疾病的啮齿动物模型中的作用。Zucker-obese大鼠的治疗 BT 2，BDK的小分子抑制剂，或表达PPM 1 K的重组腺病毒降低了循环 支链氨基酸和支链酮酸水平，改善葡萄糖耐量和胰岛素敏感性， 脂肪酸氧化，同时显著降低肝脏甘油三酯。磷酸化蛋白质组学分析显示， BDK和PPM 1 K除了具有调节BCKDH活性的功能外，还调节BCKDH的磷酸化。 关键脂肪生成酶，ATP-柠檬酸裂解酶（ACL）。尽管BCKDH的磷酸化抑制其活性， ACL的磷酸化是一种激活性翻译后修饰， 脂肪生成我们还证明，营养过剩或果糖喂养激活碳水化合物传感 转录因子ChREBP上调BDK和ACL表达，同时抑制PPM 1 K。 总之，这些研究定义了一个整合葡萄糖、脂质和支链氨基酸代谢的新的调节节点， 参与代谢疾病的进展。目前的研究旨在了解慢性 在多种饮食环境中操纵ChREBP/BDK/PPM 1 K调控节点，并扩大我们的人类 研究包括遗传和饮食变量的评估，通过以下具体目标：1）测试 假设慢性肝脏BDK过度表达将加重代谢疾病表型; 2）为了检验 假设慢性肝脏PPM 1 K过表达或ChREBP抑制将减弱或阻止 代谢性疾病表型的发展; 3）确定是否消耗含糖甜味剂 饮料（SSB）与循环BCAA水平有关，以及是否存在遗传变异， ChREBP/BDK/PPM 1 K调节节点与糖消耗相互作用，以调节BCAA水平和其他 人类的代谢特征。

.PROJECT SUMMARY – R01 Newgard/Herman . Studies performed by our group have helped establish that branched-chain amino acids (BCAA) and related metabolites are associated with insulin resistance and T2D, predictive of diabetes development and intervention outcomes, and highly responsive to therapeutic interventions. The goal of this proposal is to fully understand the metabolic and molecular mechanisms linking concerted dysregulation of BCAA, glucose and lipid metabolism. Key recent findings leading to this proposal emerged when we altered branched-chain ketoacid dehydrogenase (BCKDH) complex activity via pharmacologic and molecular manipulation of its regulatory kinase (BDK) and phosphatase (PPM1K) in rodent models of obesity and metabolic disease. Treatment of Zucker-obese rats with BT2, a small molecule inhibitor of BDK, or a recombinant adenovirus expressing PPM1K lowered circulating BCAA and branched chain ketoacid levels, improved glucose tolerance and insulin sensitivity, and increased fatty acid oxidation while markedly decreasing liver triglycerides. Phosphoproteomics analysis revealed that in addition to their function to modify BCKDH activity, BDK and PPM1K also regulate the phosphorylation of the key lipogenic enzyme, ATP-citrate lyase (ACL). Whereas phosphorylation of BCKDH inhibits its activity, phosphorylation of ACL is an activating post-translational modification that leads to increased de novo lipogenesis. We also demonstrated that overnutrition or fructose feeding activates the carbohydrate sensing transcription factor, ChREBP, which upregulates both BDK and ACL expression while suppressing PPM1K. Altogether, these studies define a novel regulatory node integrating glucose, lipid, and BCAA metabolism that participates in the progression of metabolic disease. The current study seeks to understand the impact of chronic manipulation of the ChREBP/BDK/PPM1K regulatory node in multiple dietary contexts, and to expand our human studies to include evaluation of genetic and dietary variables, via the following specific aims: 1) To test the hypothesis that chronic hepatic BDK overexpression will exacerbate metabolic disease phenotypes; 2) To test the hypotheses that chronic hepatic PPM1K overexpression or ChREBP suppression will attenuate or prevent development of metabolic disease phenotypes; 3) To determine whether consumption of sugar-sweetened beverages (SSB) associates with circulating BCAA levels, and whether genetic variants in the ChREBP/BDK/PPM1K regulatory node interact with sugar consumption to regulate BCAA levels and other metabolic traits in human populations.