A genetic approach to understanding mechanisms of epigenetic perturbation by environment

描述(由申请人提供)：这项拟议研究的广泛目标是调查遗传机制在调节毒物暴露引起的表观遗传缺陷程度中的作用。了解这些机制及其如何影响与环境有关的疾病的易感性，极有可能对人类健康和疾病结果产生重大影响。具体地说，这项研究将检查个体之间的遗传序列差异是否决定了内分泌干扰化合物(EDC)长春花碱诱导的表观遗传扰动的程度和遗传率。长春花灵是一种抗雄激素的杀菌剂，在越来越多导致表观遗传缺陷的EDCs中位居榜首。由于这种与表观遗传变化和环境中广泛存在的内分泌细胞的联系，内分泌细胞在疾病中发挥更大作用正受到越来越多的审查。目前的研究大多集中在识别内分泌细胞的表观遗传效应，包括受影响的基因和对基因表达的影响。到目前为止，关于EDC对表观遗传干扰的直接作用方式以及导致EDC诱导的表观遗传缺陷的易感性和遗传性的因素，在机制水平上知之甚少。EDC引起的表观遗传缺陷的遗传性突出了EDC暴露除了最初暴露于子孙后代之外，还可能影响健康的可能性。这对EDC相关疾病的未来患病率和诊断能力具有重大影响。在这里，我们建议研究基因序列在顺式和反式中作为环境表观遗传反应的潜在遗传修饰物的作用。我们将主要在生殖细胞发育的关键敏感窗口期间分析长春花碱引起的表观遗传缺陷，当时全基因组表观遗传重新编程正在发生。生殖细胞中发生的表观遗传缺陷可能是环境诱导的表观突变的种系传递(遗传性)的来源。我们的重点是在印记的H19/Igf2基因座引起的表观遗传缺陷。该基因座是表观遗传调控的极佳模型，因为其一致且稳定的遗传表观遗传状态，细胞间DNA甲基化水平几乎没有变化。 该基因座的表观遗传状态与基因表达之间的直接关联，使得表观遗传状态的变化总是导致基因表达的变化；以及该基因座正常表观遗传状态的中断与生长缺陷和癌症等疾病之间的联系。此外，最近在h19/igf2基因座表观遗传缺陷部位发现的基因突变与缺陷和表现的遗传性有关。 与之相关的人类印记障碍。在这里，我们检验了这样一个假设，即遗传序列差异在内分泌细胞引起的表观遗传缺陷的范围和遗传性中起着重要作用。为了验证这一假设，我们将筛选在EDC诱导的甲基化缺陷的已知位置内外存在遗传序列差异的小鼠模型，以确定修改EDC暴露的表观遗传效应并可能导致EDC相关疾病易感性的序列。

DESCRIPTION (provided by applicant): The broad goal of this proposed research is to investigate the role of genetic mechanisms in regulating the extent of epigenetic defects caused by toxicant exposure. Understanding these mechanisms and how they influence susceptibility to diseases related to the environment has great potential to have a major impact on human health and disease outcomes. Specifically, this study will examine whether genetic sequence differences between individuals determines the extent and heritability of epigenetic perturbation induced by the endocrine disrupting compound (EDC) vinclozolin. Vinclozolin is an antiandrogenic fungicide at the top of a growing list of EDCs that cause epigenetic defects. Because of this link to epigenetic changes and widespread presence of EDCs in the environment, EDCs are under increasing scrutiny for a greater role in disease. Most current studies focus on identifying the epigenetic effects of EDCs including genes affected and effects on gene expression. To date, very little is known at the mechanistic level regarding the direct mode of action of epigenetic perturbation by EDCs and factors that contribute to susceptibility and heritability of EDC-induced epigenetic defects. Heritability of EDC-induced epigenetic defects highlights the potential for EDC exposure to affect health beyond initial exposure into future generations. This has great implications on future prevalence and diagnostic capabilities of EDC-related disease. Here, we propose to investigate the role of genetic sequences in cis, at the site of perturbed methylation, and in trans, outside of the site of perturbed methylation as potential genetic modifiers of epigenetic response to environment. We will primarily assay vinclozolin- induced epigenetic defects during the critical susceptibility window of germ cell development when genome- wide epigenetic reprogramming is occurring. Epigenetic defects occurring in germ cells are a likely source of germ line transmission (heritability) of environmentally-induced epimutations. We focus on epigenetic defects induced at the imprinted H19/Igf2 locus. This locus is an excellent model of epigenetic regulation due to its consistent and stably inherited epigenetic states with little variation in DNA methylation levels between cell types and individuals; the direct correlation between epigenetic state at the locus and gene expression such that changes in epigenetic state always result in gene expression changes; and the link between disruption of normal epigenetic states at this locus and diseases such as growth defects and cancers. Furthermore, genetic mutations found at the site of epigenetic defects at the H19/Igf2 locus were recently linked to heritability of the defects and manifestation of the associated human imprinting disorder. Here, we test the hypothesis that genetic sequence differences play an important role in the extent and heritability of epigenetic defects caused by EDCs. To test this hypothesis we will screen mouse models with genetic sequence differences within and outside of the known site of EDC-induced methylation defects to identify sequences that modify the epigenetic effects of EDC exposure and potentially contribute to susceptibility to EDC-related disease.