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在已经确定，胚胎早期发育期间的环境暴露在以后的生命中对疾病的易感性起着关键作用。此外，怀孕期间的这种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)是一种高产量的化学品，用于聚碳酸酯塑料和环氧树脂的制造。啮齿动物的研究已经将出生前或围产期暴露于BPA与肝脏损伤、胰岛素抵抗、精子生成减少以及前列腺和乳腺发育改变联系在一起，最近的人类流行病学数据已经将BPA与代谢紊乱和肝功能改变的风险增加联系起来。这项拟议的工作提供了一个独特的机会，将最先进的无偏见的表观基因组方法与特定的定量表观遗传学技术相结合，以确定在动物模型和人类样本中宫内暴露BPA后胎儿表观基因组的剂量依赖性变化。首先，我们将通过确定母亲饮食暴露于环境相关水平的BPA后，毛色分布、成人体重和存活黄色刺鼠(Avy)小鼠后代的表观基因组范围甲基化的剂量依赖变化，来促进对成体疾病的胎儿表观基因组模式的理解。其次，在平行的人类方法中，我们将通过测量人类胎儿胎盘和肝脏样本中的总BPA(游离+结合物种)浓度来表征胎儿BPA的暴露。我们将应用甲基化DNA免疫沉淀深度测序(mDIP-seq)来识别人类基因组中与妊娠BPA低和高暴露相关的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和高通量定量甲基化测序来定位和分类小鼠和人类基因组中的亚稳定表位基因座，这些基因座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DNA分析技术进行检测。通过这种方法确定的基因组基因座将在子宫内暴露BPA后进行甲基化变化评估。该项目的成功完成将导致首个无偏见的表观基因组范围的实验表征在BPA暴露后发育不稳定的表观遗传基因座-在小鼠和人类中。在老鼠和人类基因组中识别这些基因座将不仅阐明物种依赖的环境表观遗传调控之间的相似之处，而且还将阐明它们之间的差异，从而能够开发出更相关的风险评估战略来保护人类种群。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基于表观遗传的人类疾病和障碍的新的诊断、筛查和治疗策略至关重要。 公共卫生相关性 人们越来越认识到，环境暴露于化学、营养和行为因素会改变基因的表达，影响健康和疾病，不仅通过突变基因的启动子和编码区，还通过修改表观基因组-DNA的修饰，赋予额外的一层可遗传的基因调控，当基因调控解除时，导致疾病。这项赠款申请的总体目标是确定妊娠期间暴露于双酚A(BPA)后的表观基因组范围的变化，双酚A是一种高产量的化学品，用于制造聚碳酸酯塑料和环氧树脂，并绘制出发育不稳定的表观遗传基因图，以促进人类健康风险评估和人类疾病的预防、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.