AhR-dependent Pkm2 regulation in NAFLD progression

项目摘要 环境污染物2，3，7，8-四氯二苯并-对-二恶英的毒性机理 （TCDD）和相关化合物仍然知之甚少，除了芳基的活化外， 碳氢化合物受体（AhR）。TCDD诱导异生物质代谢酶， 增加活性氧（ROS）。流行病学和啮齿动物研究进一步证实了 AhR激活与非酒精性脂肪性肝病的发生和进展有关 （NAFLD）。我们的初步数据表明，AhR配体诱导一种新的抗氧化剂 涉及丙酮酸激酶M2（PKM2）同种型表达的机制。PKM2 表达导致代谢重编程，重定向积累的糖酵解中间体 戊糖磷酸途径（PPP）和丝氨酸生物合成，以增加NADPH水平， 谷胱甘肽的产生支持细胞的抗氧化反应。该提案将建立一个 AhR激活、代谢重编程、抗氧化防御和 在小鼠和人类模型中的NAFLD病理学进展，通过（1）证明AhR Pkm2表达的调节，（2）追踪13 C-葡萄糖和13 C-谷氨酰胺的重定向 PPP和谷胱甘肽生物合成的中间体，以及（3）研究抗氧化作用 Pkm2在肝脂肪变性发展为脂肪性肝炎伴纤维化中的作用， 监视免疫细胞群体和肠道微生物组的生态失调。总的来说，这些 研究将证明AhR介导的PKM2诱导是一种新的细胞防御， 机制，并代表了一个重大进展，在阐明的TCDD肝毒性 和相关化合物，重点关注NAFLD的发展和进展。

Project Summary The mechanism of toxicity for the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds remains poorly understood, beyond activation of the aryl hydrocarbon receptor (AhR). TCDD induces xenobiotic metabolizing enzymes with subsequent increases in reactive oxygen species (ROS). Epidemiological and rodent studies have further implicated AhR activation in the development and progression of non-alcoholic fatty liver disease (NAFLD). Our preliminary data demonstrates that AhR ligands induce a novel antioxidant mechanism involving the expression of the pyruvate kinase M2 (PKM2) isoform. PKM2 expression causes metabolic reprogramming that redirects accumulating glycolytic intermediates to the pentose phosphate pathway (PPP) and serine biosynthesis to increase NADPH levels and glutathione production in of support cellular antioxidant responses. This proposal will establish a mechanistic link between AhR activation, metabolic reprogramming, antioxidant defenses, and progression of NAFLD pathologies in mouse and human models by (1) demonstrating AhR regulation of Pkm2 expression, (2) tracking the redirection of 13C-glucose and 13C-glutamine intermediates to the PPP and glutathione biosynthesis, and (3) investigating the antioxidant role of Pkm2 in the progression of hepatic steatosis to steatohepatitis with fibrosis, modulation of tumor surveillance immune cell populations, and dysbiosis of the gut microbiome. Collectively, these studies will demonstrate that AhR-mediated PKM2 induction is a novel cellular defense mechanism, and represents a major advancement in the elucidation of the hepatotoxicity of TCDD and related compounds, with a focus on the development and progression of NAFLD.