Regulation of methionine metabolism in NASH by PPARgamma

项目摘要/摘要 非酒精性脂肪性肝病(NAFLD)是慢性肝病的主要原因，在全球范围内 患病率为25%，且未经FDA批准的药物治疗。噻唑烷二酮(TZD)是 过氧化物酶体增殖物激活受体γ(PPARγ)激动剂，是治疗非酒精性脂肪肝的一种有潜力的药物。 然而，PPARγ是一种核受体和众所周知的脂肪生成因子，在肝细胞中表达， 通过促进肝脏新生脂肪生成(DNL)和脂肪酸摄取，促进NAFLD的发展。 我们已经评估了肝细胞PPARγ在非酒精性脂肪性肝炎(NASH)发展中的作用。 与成年性肝细胞特异性PPARG基因敲除(PPARG∆HEP)小鼠一起获得我们的K01奖。具体来说，我们有 研究表明，肝细胞PPARγ参与了NASH小鼠炎症和纤维化的发生， 提示肝细胞PPARγ对肝脏健康具有有害作用。此外，肝细胞PPARγ的缺失 ∆HEP小鼠增强TZD的抗脂肪生成、抗炎和抗纤维化作用 纳什的名字。有趣的是，我们的RNAseq和代谢组学数据表明，肝细胞PPARγ改变了 蛋氨酸在肝脏中的代谢。蛋氨酸对NAFLD起着关键的保护作用，而 PPARγ对其代谢的影响可能解释了为什么TZD介导的肝细胞PPARγ的激活降低了 TZD治疗NASH的疗效观察在这个项目中，我们假设肝细胞pparγ破坏蛋氨酸。 通过调节基因表达和甲基化能力促进脂肪变性和肝损伤 磷脂酰乙醇胺和同型半胱氨酸。为了验证这一假说，我们将确定受调控的基因 用PPARγ控制NASH中蛋氨酸使用的染色质免疫沉淀测序 对照组和给予TZD的PPARG∆HEP小鼠(目标1)。此外，我们将确定PPARγ是否直接中断 蛋氨酸在正常和PPARG∆HEP NASH小鼠原代肝细胞中的应用 同位素(目标2)。总之，我们将确定肝细胞PPARγ是如何直接调节蛋氨酸代谢的 病理生理条件。该项目的结果将帮助我们在R01中开发新的方法 建议将针对临床前模型中的特定机制来改善NASH逆转。

Project Summary/Abstract Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease with a worldwide prevalence of 25%, and without a FDA-approved pharmacological therapy. Thiazolidinediones (TZD) are the agonists of peroxisome proliferator-activated receptor γ (PPARγ), and they are a potential therapy for NAFLD. However, PPARγ is a nuclear receptor and well-known steatogenic factor expressed in hepatocytes that contributes to the development of NAFLD by enhancing hepatic de novo lipogenesis (DNL) and fatty acid uptake. We have assessed the role of hepatocyte PPARγ in the development of non-alcoholic steatohepatitis (NASH) with adult-onset hepatocyte-specific Pparg knockout (Pparg∆Hep) mice in our K01 award. Specifically, we have shown that hepatocyte PPARγ contributes to the onset of inflammation and fibrosis in mice with NASH, suggesting a deleterious role of hepatocyte PPARγ on liver health. In addition, loss of hepatocyte PPARγ in Pparg∆Hep mice enhances the anti-steatogenic, anti-inflammatory, and anti-fibrogenic actions of TZD in a model of NASH. Interestingly, our RNAseq and metabolomics data indicated that hepatocyte PPARγ altered the metabolism of methionine in the liver. Methionine plays a key protective role against NAFLD, and the effect of PPARγ on its metabolism may explain why TZD-mediated activation of hepatocyte PPARγ reduced the therapeutic effects of TZD in NASH. In this project, we hypothesize that hepatocyte PPARγ disrupts methionine metabolism and promotes steatosis and liver injury by regulating gene expression and the ability to methylate phosphatidylethanolamine and homocysteine. In order to test this hypothesis, we will identify the genes regulated by PPARγ to control the use of methionine in NASH with chromatin immunoprecipitation sequencing in samples of control and Pparg∆Hep mice treated with TZD (Aim 1). In addition, we will determine if PPARγ directly disrupts the use of methionine in mouse primary hepatocytes of control and Pparg∆Hep mice with NASH using stable isotopes (Aim 2). Overall, we will determine how hepatocyte PPARγ regulates directly methionine metabolism in pathophysiological conditions. The results of this project will help us to develop novel approaches in our R01 proposals that will target specific mechanisms in preclinical models to improve NASH reversion.