In Utero Exposure to Bisphenol A: Effects on the Fetal Epigenome

描述（由申请人提供）： 流行病学研究和动物实验现已确定，早期胚胎发育期间的环境暴露在以后的生活中对疾病易感性起着关键作用。此外，妊娠期间的此类暴露通过表观遗传机制与随后的疾病形成直接相关。双酚A（BPA）是一种高产量化学品，用于生产聚碳酸酯塑料和环氧树脂。啮齿类动物研究表明，产前或围产期BPA暴露与肝损伤、胰岛素抵抗、精子生成减少、前列腺和乳腺发育改变有关，最近的人类流行病学数据表明，BPA与代谢紊乱和肝功能改变的风险增加有关。所提出的工作提供了一个独特的机会，将联合收割机最先进的无偏表观基因组方法与特定的定量表观遗传学技术相结合，以鉴定动物模型和人类样本中子宫内BPA暴露后胎儿表观基因组的剂量依赖性改变。首先，我们将通过确定剂量依赖性改变毛色分布，成年体重，和可行的黄色琼脂糖（Avy）小鼠后代的表观基因组甲基化后，母体饮食暴露于环境相关水平的BPA，来促进对胎儿表观基因组模式的理解。其次，在一个平行的人类方法中，我们将通过测量人类胎儿胎盘和肝脏样本中的总BPA（游离加结合物种）浓度来表征胎儿BPA暴露。我们将应用甲基化DNA免疫沉淀深度测序（mDIP-seq）来鉴定与低与高妊娠BPA暴露相关的人类基因组中表观基因组范围的甲基化模式。最后，我们将利用组织特异性表达谱分析和高通量定量甲基化测序来绘制和分类小鼠和人类基因组中的亚稳态表观等位基因位点，这些位点由于其调控和编码区的高度重复内容而无法使用目前可用的表观基因组范围的DNA测定技术来检测。通过这种方法鉴定的基因组位点将在子宫内BPA暴露后评估甲基化的改变。该项目的成功完成将导致第一个无偏见的表观基因组范围内的实验表征发育不稳定的表观遗传基因座的剧目后，BPA暴露-在小鼠和人类。在小鼠和人类基因组中识别这些基因座不仅可以阐明物种依赖性环境表观遗传调控之间的相似性，还可以阐明它们之间的差异，从而为保护人类种群制定更相关的风险评估策略。从拟议的研究中产生的知识对于破译早期表观遗传编程在成人疾病发病机制中的作用以及开发新的基于表观遗传的人类疾病和障碍的诊断，筛查和治疗策略至关重要。 公共卫生相关性 越来越多的人认识到，暴露于化学、营养和行为因素的环境不仅通过突变基因的启动子和编码区，而且通过修饰表观基因组改变基因表达并影响健康和疾病，表观基因组修饰赋予额外的一层遗传基因调控，当失调时导致疾病。这项资助申请的总体目标是确定妊娠期暴露于双酚A（BPA）后的表观基因组变化，双酚A是一种用于制造聚碳酸酯塑料和环氧树脂的高产量化学品，并绘制发育不稳定的表观遗传基因，以促进人类健康风险评估和人类疾病预防，诊断和治疗。

DESCRIPTION (provided by applicant): Epidemiological studies and animal experiments have now firmly established that environmental exposures during early embryonic development play a critical role in disease susceptibility in later life. Moreover, such exposures during gestation have been directly linked with subsequent disease formation through epigenetic mechanisms. Bisphenol A (BPA) is a high-production volume chemical used in the manufacture of polycarbonate plastic and epoxy resins. Rodent studies have associated pre- or perinatal BPA exposure with liver damage, insulin resistance, decreased sperm production, and altered prostate and mammary gland development, and recent human epidemiological data have linked BPA with increased risk of metabolic disorders and altered liver function. The proposed work presents a unique opportunity to combine state-of-the- art unbiased epigenomic approaches with specific quantitative epigenetic techniques to identify dose- dependent alterations in the fetal epigenome following in utero BPA exposure in both animal model and human samples. First, we will advance understanding of fetal epigenomic patterning of adult disease by identifying dose-dependent alterations in coat color distribution, adult body weight, and epigenome-wide methylation of viable yellow agouti (Avy) mouse offspring following maternal dietary exposure to environmentally relevant levels of BPA. Second, in a parallel human approach, we will characterize fetal BPA exposure by measuring total BPA (free plus conjugated species) concentrations in human fetal placenta and liver samples. We will apply methylated DNA immunoprecipitation deep-sequencing (mDIP-seq) to identify epigenome-wide methylation patterns in the human genome associated with low versus high gestational BPA exposure. Finally, we will utilize tissue specific expression profiling and high-throughput quantitative methylation sequencing to map and categorize metastable epiallelic loci in the mouse and human genomes that cannot be detected using currently available epigenome-wide DNA assay technologies due to the highly repetitive content of their regulatory and coding regions. Genomic loci identified through this approach will be assessed for altered methylation following in utero BPA exposure. The successful completion of this project will result in the first unbiased epigenome-wide experimental characterization of the repertoire of developmentally labile epigenetic loci following BPA exposure - in both mice and humans. Identifying these loci in both the mouse and human genomes will elucidate not only the similarities but also the differences between species-dependent environmental epigenetic regulation, allowing for the development of more relevant risk assessment strategies for protecting human populations. Knowledge generated from the proposed studies is crucial for deciphering the role of early epigenetic programming in the pathogenesis of adult disease and for the development of novel epigenetic-based diagnostic, screening, and therapeutic strategies for human diseases and disorders. PUBLIC HEALTH RELEVANCE It is increasingly recognized that environmental exposure to chemical, nutritional, and behavioral factors alters gene expression and affects health and disease by not only mutating promoter and coding regions of genes, but also by modifying the epigenome - modifications to DNA that confer an additional layer of heritable gene regulation that lead to disease when deregulated. The overall objective of this grant application is to identify epigenome-wide alterations following gestational exposure to bisphenol a (BPA), a high production volume chemical used in the manufacturing of polycarbonate plastics and epoxy resins, and to map developmentally labile epigenetic genes in order to facilitate human health risk assessment and human disease prevention, diagnosis, and treatment.