Epigenetic regulation of hepatic gene expression in the pathogenesis of insulin resistance

先前我和其他人发现2型糖尿病（T2D）与肥胖受试者肝脏DNA甲基化的变化有关。然而，糖尿病肝脏中DNA甲基化如何调节基因表达的确切机制以及这些改变是否有助于肝脏胰岛素抵抗仍然是未知的。我的项目提案旨在确定肝脏中重要代谢基因的动态表观遗传调控，以增加我们对胰岛素抵抗的理解，并确定新的治疗方法来逆转与肥胖和2型糖尿病相关的表观遗传改变的基因表达程序。第六年发现的新目标是：新颖1.1。2型糖尿病肥胖和DIO患者肝脏microRNA表达与WGBS的关系Galnt18-/-小鼠的初始代谢特征在第一个资助期，收集了肥胖的t2糖尿病和非糖尿病受试者的肝脏活检。此外，还进行了一项小鼠纵向研究，在高脂肪喂养开始后的第1、2、4、5、6、7、8和12周，采集饮食诱导的肥胖小鼠的肝脏。目的1.1将在这些人类和小鼠肝脏样本中进行microRNA和全基因组二硫测序（WGBS）数据分析，以发现2TD中表观遗传失调的基因，并追踪这些变化是否动态并导致胰岛素抵抗的发生。在第一个资助期，我们已经确定基因组和表观遗传改变与肝脏中转录因子结合和T2D的改变有关。增加更多的全基因组数据将提升该项目，并保证更有效地识别导致肝脏胰岛素抵抗的表观遗传机制。此外，在延长的资助期内，将详细研究导致DNA甲基化改变的分子机制。目标2.4。将表征Galnt18缺陷小鼠（Galnt18-/-）的葡萄糖和能量代谢。GALNT18对糖蛋白的形成很重要，但GALNT18的代谢功能目前尚不清楚。Galnt18-/-小鼠目前正在当地动物设施进行繁殖，以扩大菌落，初步数据显示Galnt18-/-小鼠的血糖和血浆胰岛素浓度降低。在正常和高脂肪喂养条件下，这些小鼠的体重、食物摄入量、身体组成、葡萄糖和胰岛素耐量以及能量代谢将在全身水平上得到表征。发现新的糖尿病致病基因对了解糖尿病的发病机制和制定未来的治疗策略具有重要意义。

Previously I and others showed that type 2 diabetes (T2D) is associated with changes in DNA methylation in liver of obese subjects. However, the precise mechanism how gene expression is regulated by DNA methylation in the diabetic liver and whether these alterations contribute to hepatic insulin resistance remain mostly unknown. My project proposal aims to identify dynamic epigenetic regulation of important metabolic genes in the liver to increase our understanding of insulin resistance and to identify novel therapeutic approaches to reverse the epigenetically altered gene expression programs associated with obesity and T2DM.New aims that are added for the sixth year of finding are:novel 1.1. microRNA expression and WGBS in liver of T2-diabetic obese subjects and DIO micenovel 2.4. Initial metabolic characterization of Galnt18-/- miceDuring the first funding period liver biopsies form obese T2-diabetic and non-diabetic subjects were collected. Furthermore, a longitudinal mouse study was performed in which liver from diet-induced obese mice was harvested 1, 2, 4, 5, 6, 7, 8 and 12 weeks after onset of high-fat feeding. In aims 1.1 analysis of microRNA and whole-genome bisulfide sequencing (WGBS) data will be performed in these human and mouse liver samples to find genes that are epigenetically dysregulated in 2TD and to track if these changes are dynamic and causal for the development of insulin resistance. During the first funding period we already identified that genomic and epigenetic alterations are associated with altered transcription factor binding and T2D in liver. Adding more genome-wide data will elevate the project and guarantee a more efficient identification of epigenetic mechanisms leading to hepatic insulin resistance. Moreover, molecular mechanisms leading to altered DNA methylation will be studied in detail in the expended funding period.Aim 2.4. will characterize the glucose and energy metabolism of Galnt18-deficient mice (Galnt18-/-). GALNT18 is important for formation of glycoproteins but metabolic functions of GALNT18 are currently unknown. Galnt18-/- mice are currently breeding at the local animal facility for colony expansion and first data show that Galnt18-/- mice have reduced blood glucose and plasma-insulin concentrations. The body-weight, food intake, body composition, glucose- and insulin tolerance and energy metabolism will be characterized in these mice under normal and high-fat feeding conditions on a whole-body level. Finding novel diabetes disease genes is of high importance for understanding and diabetes pathogenesis and to develop future treatment strategies.