Epigenetic Determinants of Lipid Response to Dietary Fat and Fenofibrate

描述(申请人提供)：血脂异常在心血管疾病的发生中起着重要作用，这激发了人们对更好地了解导致血脂异常的环境因素，特别是高甘油三酯血症的兴趣。表观遗传变异可能会影响甘油三酯(TG)的代谢和对环境挑战的反应。我们的目标是进行第一次实验，全面扫描表观基因组，寻找甘油三酯和其他血脂异常反应的决定因素，以应对两种“环境”干预，一种是提高TGS(高脂餐)，另一种是降低TGS(为期3周的非诺贝特治疗)。这些实验将在NHLBI项目中进行，该项目位于基因-环境相互作用网络的“降脂与饮食遗传学”(GOLDN)研究中。GOLDN从明尼苏达州和犹他州的现场中心招募了家庭成员，并对他们进行了广泛的酶和核磁共振血脂以及炎症标志物的表型鉴定，以回应这两项干预。这项拟议的研究将以这一独特的资源为基础，使用以前收集的样本来实现以下目标：(1)使用下一代测序方法，特别是简化代表性亚硫酸盐测序方法，在184个家庭的1,048个个体中进行全基因组CpG甲基化分析，以确定在非诺贝特治疗的情况下，TGS和TG相关表型对脂肪餐、非诺贝特和脂肪餐的反应的表观遗传变异。从这些结果中，我们将选择20个候选基因，为AIM 2的进一步鉴定提供最好的证据。(2)通过对所有1,048个家庭成员的启动子和其他感兴趣区域的亚硫酸氢盐测序来表征这20个基因的甲基化状态。(3)在外部队列中重复AIMS 1和AIMS 2的重要发现。(4)进行基因表达研究，以确定AIMS 1-3的甲基化结果对功能的影响，因为DNA甲基化可能以各种方式影响邻近基因的表达，包括转录速率、选择性剪接、microRNA抑制或等位基因特异性表达。我们将使用一种名为RNAseq的方法对150名受试者的mRNA和microRNA进行下一代测序。如果成功，我们将识别新的表观遗传学变异，预测对饮食脂肪反应差或对非诺贝特有利的个体，这将导致开发有针对性的干预措施，以更有效地预防和治疗高甘油三酯血症。 公共卫生相关性：表观遗传学是一个相对较新的研究领域，它试图了解基因活动而不是基因结构如何影响人的特征。表观遗传因素可能解释了为什么一些人在吃了高脂餐或服用降脂药物后，血液中的脂肪和胆固醇水平会发生巨大变化，而另一些人在相同条件下的脂肪和胆固醇水平变化很小。这项研究旨在发现导致人们的身体对饮食和药物做出如此不同反应的表观遗传因素，相信这些知识最终可以帮助降低人们患心血管疾病的风险。

DESCRIPTION (provided by applicant): Dyslipidemias play a large role in the occurrence of cardiovascular disease, which has fueled interest to better understand environmental factors responsible for dyslipidemias, especially hypertriglyceridemia. Epigenetic variations may affect triglyceride (TG) metabolism and response to environmental challenges. Our goal is to conduct the first experiments that will comprehensively scan the epigenome for determinants of TG and other dyslipidemic responses to two "environmental" interventions, one to raise TGs (a high-fat meal), and one to lower TGs (3-week fenofibrate treatment). These experiments will be conducted in the NHLBI Program in Gene-Environment Interaction Network's "Genetics of Lipid Lowering and Diet" (GOLDN) study. GOLDN recruited family members from field centers in Minnesota and Utah and phenotyped them extensively for enzymatic and NMR lipids and inflammatory markers in response to the two interventions. The proposed study will build upon this unique resource using previously collected samples to implement the following aims: (1) Conduct genome-wide CpG methylation analysis, using next generation sequencing method, specifically, Reduced Representation Bisulfite Sequencing, in 1,048 individuals from 184 families to identify epigenetic variation contributing to the response of TGs and TG-related phenotypes to a fat meal, fenofibrate, and a fat meal in the context of fenofibrate treatment. From these results, we will select 20 candidate genes with the best evidence for further characterization in Aim 2. (2) Characterize the methylation state of these 20 genes using bisulfite sequencing of promoters and other regions of interest in all 1,048 family members. (3) Replicate significant findings from Aims 1 and 2 in external cohorts. (4) Conduct gene expression studies to identify the functional impact of methylation findings from Aims 1-3 since DNA methylation may affect the expression of nearby genes in a variety of ways, including transcription rates, alternative splicing, microRNA inhibition, or allele specific expression. We will apply next-generation sequencing to both mRNA and microRNA from 150 subjects using a method called RNAseq. If successful, we will identify novel epigenetic variations that predict individuals who respond poorly to dietary fat or favorably to fenofibrate which will lead to the development of targeted interventions to more effectively prevent and treat hypertriglyceridemia. PUBLIC HEALTH RELEVANCE: Epigenetics is a relatively new area of study which seeks to understand how gene activity rather than gene structure influences people's traits. Epigenetic factors may explain why the levels of fat and cholesterol in some people's blood change dramatically after eating a high-fat meal or after taking fat-lowering drugs while fat and cholesterol levels in other people change very little under the same conditions. This study aims to discover the epigenetic factors that cause people's bodies to respond so differently to diet and drugs with the belief that such knowledge could ultimately help lower people's risk for cardiovascular disease.