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

.产品摘要-R01纽加德/赫尔曼。 我们小组进行的研究帮助建立了支链氨基酸(BCAA)和相关的 代谢产物与胰岛素抵抗和T2D相关，预测糖尿病的发展和干预 结果，并对治疗干预措施高度响应。这项建议的目标是充分了解 与支链氨基酸、糖脂代谢协调失调相关的代谢和分子机制。 当我们改变支链酮酸脱氢酶时，导致这一提议的关键最近发现出现了 (BCKDH)通过药理和分子操作其调节激酶(BDK)和 肥胖和代谢性疾病啮齿动物模型中的磷酸酶(PPM1K)。丹参对Zucker肥胖大鼠的治疗作用 BDK小分子抑制剂BT2或表达PPM1K的重组腺病毒降低循环 支链氨基酸和支链酮酸水平，改善糖耐量和胰岛素敏感性，并增加 脂肪酸氧化的同时明显降低肝脏甘油三酯。磷蛋白质组学分析显示，在 BDK和PPM1K除了具有修饰BCKDH活性的功能外，还调节BCKDH的磷酸化。 关键的脂肪生成酶，三磷酸腺苷-柠檬酸裂解酶(ACL)。而BCKDH的磷酸化则抑制其活性， ACL的磷酸化是一种激活的翻译后修饰，导致从头开始增加 脂肪生成作用。我们还证明了营养过剩或喂食果糖会激活碳水化合物感觉。 转录因子ChREBP，它上调BDK和ACL的表达，同时抑制PPM1K。 总之，这些研究定义了一个新的调节节点，整合了葡萄糖、脂肪和支链氨基酸代谢， 参与代谢性疾病的进展。目前的研究试图了解慢性疾病的影响 在多种饮食环境中操纵ChREBP/BDK/PPM1K调控节点，并扩大我们的人类 研究包括评估遗传和饮食变量，通过以下具体目标：1)测试 慢性肝脏BDK过度表达将加剧代谢性疾病表型的假设；2)检验 慢性肝脏PPM1K过度表达或抑制ChREBP将减弱或预防的假说 代谢性疾病表型的发展；3)确定是否摄入甜味剂 饮料(SSB)与循环中的支链氨基酸水平有关，以及 ChREBP/BDK/PPM1K调节节点与糖的消耗相互作用，调节支链氨基酸水平等 人类群体中的代谢特征。

.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.