Characterizing the Human Imprint Regulatory Regions Associated with Childhood Obesity

项目总结/摘要 在过去的30年里，肥胖症的流行率迅速增加，这导致了一种假设，即表观遗传机制 介导环境线索和肥胖结果之间的关联。然而，改变肥胖的表观遗传区域 风险在很大程度上仍然未知。我们目前缺乏一个筛选工具，全面衡量表观遗传修饰。 在任何感兴趣的疾病或暴露中进行这样的筛查将对广泛的人类健康研究具有很大的实用性。的 使用基因组规模方法产生的人类表观遗传数据的解释受到三个主要障碍的阻碍。 首先，可用数据主要基于在不同温度下通过横断面获得的DNA中测量的甲基化差异 在整个生命过程中，DNA甲基化标记是随着年龄而变化的。其次，虽然甲基化是 已知其因细胞和组织类型而异，测量是在可从其它细胞和组织获得的可获得的外周细胞类型中进行的。 健康的个体，并不总是与那些导致肥胖的细胞类型相关。第三，修改 表观遗传标记可以由肥胖引起，暴露和结果之间的这种时间模糊性使因果关系复杂化。 推论为了克服这些障碍，我们将全面鉴定印记基因的调控DNA甲基化， 创造了人类“印记”的初稿。表观遗传调控的印记基因估计占1-2% （200-400个基因）的人类基因组，并在早期胚胎的发展至关重要;然而，只有约30个印记， 已知调控70-80个基因的控制区（ICR）。印迹基因的单等位基因表达受亲本- 在ICR处的起源特异性DNA甲基化，其在胚层特化之前建立并在体细胞中维持。 生命中的组织因此，调控这些基因表达的甲基化标记在功能上是相关的， 在不同的细胞类型、不同的个体以及整个衰老过程中都是保守的。ICR的这些独特功能提供了一种 一个全面的工具，用于早期获得的表观遗传修饰的多重测量，并评估它们之间的联系， 暴露和疾病之间的联系我们的首要目标是使用全基因组方法系统地识别所有ICR 使用各种各样的样本，包括来自广泛年龄范围的男性和女性的多种细胞类型。通过这种方式， 鉴定可以仅限于在细胞类型、性别和细胞周期中一致的差异甲基化区域（DMR）。 年龄-ICR的标志。然后将通过在脐带中识别， 出生时的血液，ICR模式预测儿童后期的肥胖。识别改变的印记监管将提供标记 进行前瞻性风险评估，确定导致肥胖发展的机制，并为未来的研究提供信息， 影响肥胖的环境暴露。一旦开发出来，这种ICR筛选试验也将用于识别 与任何疾病或暴露相关的早期表观遗传扰动区域，为 了解这些疾病的胎儿起源

PROJECT SUMMARY/ABSTRACT The rapid increase in the prevalence of obesity in the last 30 years has led to the hypothesis that epigenetic mechanisms mediate associations between environmental cues and obesity outcomes. Nevertheless, epigenetic regions that alter obesity risk are still largely unknown. We presently lack a screening tool for comprehensive measurement of epigenetic modifications. Such a screen in any disease or exposure of interest would be of great utility for a broad range of human health studies. The interpretation of human epigenetic data generated using genome-scale approaches is hampered by three main obstacles. Firstly, available data are largely based on methylation differences measured in DNA obtained cross-sectionally at different ages throughout the life course, yet DNA methylation marks are known to vary by age. Secondly, although methylation is known to vary by cell and tissue types, measurements are made in accessible peripheral cell types accessible from otherwise healthy individuals, and do not always correlate with those of cell types that contribute to obesity. Thirdly, alteration to epigenetic marks can be caused by obesity, and this temporal ambiguity between exposure and outcome complicates causal inference. To overcome these obstacles, we will comprehensively identify regulatory DNA methylation for imprinted genes, creating the first draft of the human “imprintome”. Epigenetically regulated imprinted genes are estimated to comprise 1-2% (200-400 genes) of the human genome, and are critical in the development of the early embryo; however, only ~30 imprint control regions (ICRs), regulating 70-80 genes, are known. Monoallelic expression of imprinted genes is regulated by parent- of-origin specific DNA methylation at ICRs that is established prior to germ-layer specification and maintained in somatic tissues throughout life. Therefore, methylation marks regulating the expression of these genes are functionally relevant, and are conserved across cell types, among individuals, and throughout aging. These unique features of ICRs provide a means to a comprehensive tool for multiplexed measurement of early acquired epigenetic modifications, and assess their link between exposures and disease. Our overarching goal is to use genomewide approaches to systematically identify all ICRs using a wide variety of samples, including multiple cell types from males and females from a wide age range. In this way, identification can be restricted to only differentially methylated regions (DMRs) that are consistent across cell type, sex, and age – the hallmark of ICRs. The ICR panel will then be evaluated in relationship to obesity, by identifying, in umbilical cord blood at birth, ICR patterns predictive of obesity later in childhood. Identifying altered imprint regulation will provide markers for prospective risk assessment, identify mechanisms contributing to obesity development, and inform future research into environmental exposures affecting obesity. Once developed, this ICR screening assay would also then be used to identify regions of early epigenetic perturbation associated with any disease or exposure, creating new opportunities for understanding the fetal origins of these conditions.