Epigenetics of Obesity and Insulin Resistance

描述（由申请人提供）：该提案的目标是双重的：（i）研究肥胖症中胰岛素靶组织中转录的表观遗传调控，以及（ii） 为未来的R 01融资提供平台。PI是一名经过NIH培训的儿科内分泌学家，擅长基础科学研究，目前在UCSD任教。肥胖和胰岛素抵抗是2型糖尿病、心血管疾病和中风的主要危险因素。这些代谢性疾病与遗传和环境因素引起的基因表达的深刻改变有关。表观遗传学提供了一种机制，通过这种机制，环境因素可以改变所有年龄段的基因表达和疾病易感性。基因调控的表观遗传机制包括DNA甲基化和组蛋白修饰。高度近交的啮齿动物品系如C57 BL/6小鼠在遗传上几乎相同。然而，这些菌株在寿命、肥胖和胰岛素抵抗方面表现出很大的差异。表观遗传变异是解释这种高表型变异性的一个可能因素。在这个提议中，我们利用高脂饮食（HFD）喂养的C57 BL/6雄性小鼠的广泛代谢变异作为研究表观遗传修饰如何调节肥胖和胰岛素的转录控制的手段。 阻力为了实现这一目标，我们将应用高通量技术（ChIP-Seq和RNA-Seq）来调查C57 BL/6小鼠脂肪和肝脏组织中的全局表观遗传组蛋白修饰和转录组谱。我们假设i）HFD改变肝脏和脂肪组织中的组蛋白修饰模式（目的1），和ii）表观遗传差异解释了HFD后胰岛素抵抗的广泛变化（目的2）。在目标1中，我们将比较从喂食HFD或标准食物的年龄匹配的小鼠收集的组织。在目标2中，我们将通过手术从幼龄小鼠中取出组织并储存，将所有小鼠置于HFD上，并进行代谢测试以定义具有重度或轻度胰岛素的2个不同的小鼠亚组 阻力然后，我们将分析研究开始时收集的组织，比较两个表型组之间的差异。在这两个目标中，组织将进行ChIP-Seq分析，以确定标记活性启动子和阻遏物元件（即H3 K4 me 3和H3 K27 me 3）的组蛋白甲基化模式。这些数据将与通过RNA-Seq获得的基因表达谱整合。这项工作将与加州大学圣地亚哥分校的Bing Ren博士合作进行，他是高通量技术和计算分析方面的公认专家。任博士的实验室将进行所有测序并协助进行生物信息学分析。体内实验将在我的K 08导师Jerrold Olefsky博士的实验室进行。这种方法旨在利用我作为一名实验室科学家和儿科内分泌学家的优势，为未来的R 01资金提供独立的研究重点和平台。

DESCRIPTION (provided by applicant): The goals of this proposal are two-fold: (i) to investigate epigenetic regulation of transcription in insulin target tissues in obesity and (ii) to generate a platform for future R01 funding. The PI is an NIH-trained pediatric endocrinologist skilled in basic science research, currently on faculty at UCSD. Obesity and insulin resistance are major risk factors to the development of type 2 diabetes, cardiovascular disease, and stroke. These metabolic diseases are associated with profound alterations in gene expression caused by both genetic and environmental factors. Epigenetics provides a mechanism by which environmental factors modify gene expression and the predisposition to disease at all ages. Epigenetic mechanisms of gene regulation include DNA methylation and histone modifications. Highly inbred rodent strains such as C57BL/6 mice are nearly genetically identical. Yet these strains show substantial variation in longevity, adiposity, and insulin resistance. Epigenetic variation is a likely factor to account for this high phenotypic variability. In this proposal, we exploit the wide metabolic variation in high- fat diet (HFD)-fed C57BL/6 male mice as a means to investigate how epigenetic modifications regulate transcriptional control in obesity and insulin resistance. In order to achieve this goal, we will apply high throughput techniques (ChIP-Seq and RNA-Seq) to survey global epigenetic histone modification and transcriptome profiles in adipose and liver tissue of C57BL/6 mice. We hypothesize that i) HFD alters histone modification patterns in liver and adipose tissues (Aim 1), and ii) that epigenetic differences account for the wide variation in insulin resistance following HFD (Aim 2). In Aim 1, we will compare tissues collected from age-matched mice fed either HFD or standard chow. In Aim 2, we will surgically remove and bank tissues from young mice, place all mice on HFD, and perform metabolic testing to define 2 distinct subgroups of mice with either severe or mild insulin resistance. We will then analyze tissues collected at study initiation, comparing differences between both phenotypic groups. In both aims, tissues will be subjected to ChIP-Seq analysis to determine histone methylation patterns that mark active promoter and repressor elements (namely H3K4me3 and H3K27me3). These data will be integrated with gene expression profiles obtained by RNA-Seq. This work will be conducted in collaboration with Dr. Bing Ren at UCSD, a well-recognized expert in high throughput techniques and computational analysis. Dr. Ren's lab will perform all sequencing and assist with bioinformatics analysis. The in vivo experiments will be conducted in the lab of my K08 mentor, Dr. Jerrold Olefsky. This approach is designed to draw on my strengths as a bench scientist and pediatric endocrinologist, providing an independent focus of research and platform for future R01 funding.