Epigenetic Regulation of Mitochondrial Homeostasis and Energy Metabolism

项目总结 非酒精性脂肪性肝病(NAFLD)是导致胰岛素抵抗的重要因素，而 在2型糖尿病中，两者相互调节。在NAFLD和胰岛素抵抗的肝脏中，数百人 数以千计的基因要么上调，要么下调。表观遗传修饰，如组蛋白 甲基化和乙酰化调节同染色质或异染色质状态以增强或抑制基因 以上下文相关的方式表达。然而，在绘制表观遗传学图谱方面存在着重大的知识空白 景观和确定调控NAFLD和胰岛素发生的主要表观遗传因素 抵抗。在目前的提案中，我们利用最新开发的Cut&Tag技术，创建了 组蛋白修饰的表观遗传图谱，包括H3K4me1(稳定标记)、H3K4me2和H3K27ac (活性标志)和H3K9me2(抑制标志)。一个全面的 组蛋白修饰图谱的分析确定Re1沉默转录因子(REST)是一种 协调这些组蛋白标记物活性的表观遗传调节器。REST招募组蛋白脱乙酰酶 (HDAC1&2)，用于脱乙酰化H3K27ac，以及赖氨酸特异性脱甲基酶1(LSD1)，用于脱甲基化 H3K4me1和H3K9me2，调节基因表达。我们的初步数据显示，核休眠蛋白 小鼠和人非酒精性脂肪肝的肝脏中的水平均升高。胰岛素和葡萄糖对体外培养细胞的作用 模拟胰岛素抵抗的肝细胞驱动静息核移位。用REST击倒休息 成年肥胖小鼠肝脏反义寡核苷酸(REST-LKD)减轻和改善脂肪肝 葡萄糖和胰岛素耐量。高胰岛素-正血糖钳夹研究表明，静息抑制 肝脏增加脂肪组织和肌肉中葡萄糖的摄取，表明肝脏和脂肪之间存在串扰 组织/肌肉。这些数据表明，在胰岛素抵抗时，肝脏休息是激活的，而激活的休息 促进NAFLD的发展和胰岛素抵抗，形成恶性循环。我们的中心假设是 其余的是组蛋白甲基化和乙酰化的关键表观遗传因素，以调节血脂和 NAFLD的糖代谢与胰岛素抵抗。我们提出了三个目标来调查导致休息的原因 NAFLD的激活和胰岛素抵抗，为什么激活的REST促进NAFLD和胰岛素抵抗， 以及激活的休息是如何导致全身性胰岛素抵抗的。目标1：确定 NAFLD患者肝脏静息活动增加。目的2：阐明肝脏静息的机制 调节脂肪和葡萄糖代谢。目的3：探讨改善全身性胰岛素的机制 REST-LKD小鼠的敏感性。提案的成功执行将通过绘制 表观遗传格局和确定REST为重新编程代谢基因图谱的关键表观遗传因素 非酒精性脂肪肝和胰岛素抵抗。

PROJECT SUMMARY Non-alcoholic fatty liver disease (NAFLD) contributes strongly to the development of insulin resistance, and the two mutually regulate each other in type 2 diabetes. In the liver of NAFLD and insulin resistance, hundreds to thousands of genes are either upregulated or downregulated. Epigenetic modifications such as histone methylation and acetylation modulate homochromatin or heterochromatin states to enhance or suppress gene expression in a context-dependent manner. However, significant knowledge gaps exist in mapping the epigenetic landscape and identifying the major epigenetic factors regulating the development of NAFLD and insulin resistance. In the current proposal, we take advantage of the newly developed CUT&TAG technology and create an epigenetic landscape of histone modifications, including H3K4me1 (poised marker), H3K4me2, and H3K27ac (active marker), and H3K9me2 (suppressive marker) in the liver of mouse and human NAFLD. A comprehensive analysis of the histone modification landscape identifies RE1 Silencing Transcription Factor (REST) as an epigenetic modulator that coordinates the activity of these histone markers. REST recruits histone deacetylases (HDAC1&2), which deacetylate H3K27ac, and lysine-specific demethylase 1 (LSD1), which demethylates H3K4me1 and H3K9me2, to regulate gene expression. Our preliminary data show that nuclear REST protein levels are increased in the liver of mouse and human NAFLD. Insulin and glucose treatment of cultured hepatocytes mimicking insulin resistance drives REST nuclear translocation. Knocking down REST using REST antisense oligonucleotides (ASO) in the liver of adult obese mice (REST-LKD) alleviates fatty liver and improves glucose and insulin tolerance. Hyperinsulinemic-euglycemic clamp studies show that REST knockdown in the liver increases glucose uptake in adipose tissue and muscle, indicating crosstalk between the liver and adipose tissue/muscle. These data show that hepatic REST is activated in insulin resistance, and the activated REST promotes the development of NAFLD and insulin resistance, forming a vicious cycle. Our central hypothesis is that REST is the key epigenetic factor orchestrating histone methylation and acetylation to regulate lipid and glucose metabolism in NAFLD and insulin resistance. We propose three aims to investigate what causes REST activation in NAFLD and insulin resistance, why the activated REST promotes NAFLD and insulin resistance, and how the activated REST induces systemic insulin resistance. Aim 1: To determine the mechanisms for the increased REST activity in the liver of NAFLD. Aim 2: To elucidate the mechanisms by which hepatic REST regulates lipid and glucose metabolism. Aim 3: To investigate the mechanisms for improved systemic insulin sensitivity in REST-LKD mice. Successful execution of the proposal will fill the knowledge gap by mapping the epigenetic landscape and identifying REST as a key epigenetic factor that reprograms metabolic gene profiles in NAFLD and insulin resistance.