Understanding the causes of DNA methylation response to methylmercury: a novel approach to quantify genetic, environmental, and stochastic factors

了解 DNA 甲基化对甲基汞反应的原因：一种量化遗传、环境和随机因素的新方法

• 批准号: 10039951
• 负责人: Caren Weinhouse
• 金额: $ 15.49万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-15 至 2023-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10039951
• 关键词: Affect; Alleles; Bioinformatics; Brain region; Chemical Exposure; Chemical Models; Chemicals; Cytosine; DNA; DNA Damage; DNA Methylation; DNA Sequence; Data; Development; Dinucleoside Phosphates; Dose; Environment; Epigenetic Process; Exposure to; Functional disorder; Gene Expression; Generations; Genetic; Genetic Variation; Genotype; Goals; Health protection; Heavy Metals; Hippocampus (Brain); Human; Hybrids; Inbred Strains Mice; Individual; Individual Differences; Lead; Life; Light; Link; Measures; Memory; Mentors; Methylation; Methylmercury Compounds; Modeling; Modification; Mus; Neurocognition; Neurocognitive; Parents; Phenotype; Population; Public Health; Research; Research Design; Resistance; Rodent; Single Nucleotide Polymorphism; Site; Source; System; Testing; Tissues; Toxic Environmental Substances; Toxicant exposure; Training; Variant; Work; career development; design; disorder risk; environmental chemical; experimental study; exposed human population; follow-up; gene environment interaction; genetic approach; genetic variant; genome-wide; improved; insight; inter-individual variation; methyl group; methylation pattern; methylmercury exposure; mother nutrition; neurotoxic; neurotoxicity; non-genetic; novel strategies; programs; response; toxicant; trait

PROJECT SUMMARY Environmental toxicant exposures correlate with changes to DNA methylation, or chemical modifications to DNA that regulate gene expression, but the mechanisms underlying these correlations are unknown. DNA methylation can differ in genetically identical individuals, allowing different phenotypes to develop from identical genotypes following exposure. These results suggest specific cellular responses to chemicals that lead to environmental differences in phenotype. In addition, unexposed genetically identical individuals show variability in DNA methylation, indicating that some differences are stochastic (i.e., probabilistic). In genetically different individuals, DNA methylation patterns correlate highly with genotype, both in the absence and presence of chemical exposure, indicating that some DNA methylation is under genetic control, and that some DNA methylation responses to chemicals occur in some genotypes more than others (gene-environment interactions). Here, I will test the central hypothesis that these four sources each explain equal proportions of the total DNA methylation response in genotypically different mice with developmental exposure to a model chemical, the heavy metal methylmercury (MeHg). MeHg is an ideal model chemical because it is of strong public health concern, there are known phenotypic differences in exposed humans and rodents, and MeHg does not cause DNA damage, which independently affects DNA methylation. My career development goal is to integrate new training in statistical genetics with my background in environmental epigenetics to do research that is both mechanistic and translatable to human populations. I will leverage a classic F2 intercross design between two inbred mouse strains, one susceptible (CAST/EiJ) and one resistant (C57BL/6J) to MeHg neurotoxicity. F1 hybrid mice are generated with reciprocal crosses between parent strains, and F2 hybrid mice by crossing F1 mice with opposite parentage. F1 mice are genotypically identical. F2 mice are genotypically different but carry no DNA sequence not also present in F1 mice. I will measure DNA methylation levels in hippocampus from F1 and F2 mice both with and without developmental exposure to an environmentally relevant dose (500 ng/g) of MeHg in maternal diet. DNA methylation differences in F1 exposed vs. control mice will represent environmental effects; hypervariable DNA methylation in F1 control mice will represent stochastic effects. Genetic sequence variants that predict DNA methylation in F2 control mice will represent genetic effects; sequence variants that predict differential methylation in F2 exposed vs. control will represent gene-environment interactions. These results will provide insight into causes of inter-individual differences in MeHg neurotoxicity. Critically, this work will improve our mechanistic understanding of DNA methylation response to toxicants. ! !

项目概要 环境毒物暴露与 DNA 甲基化或 DNA 化学修饰的变化相关 调节基因表达，但这些相关性背后的机制尚不清楚。 DNA甲基化 基因相同的个体可能存在差异，从而使相同的基因型发展出不同的表型 曝光后。这些结果表明细胞对化学物质的特定反应会导致环境 表型的差异。此外，未暴露的基因相同的个体表现出 DNA 变异 甲基化，表明某些差异是随机的（即概率性的）。在基因不同的个体中， DNA 甲基化模式与基因型高度相关，无论是否存在化学物质 暴露，表明某些 DNA 甲基化受到遗传控制，并且某些 DNA 甲基化 对化学物质的反应在某些基因型中比其他基因型发生得更多（基因-环境相互作用）。在这里，我将 检验中心假设，即这四个来源各自解释了总 DNA 甲基化的相同比例 基因型不同的小鼠在发育过程中接触模型化学物质（重金属）的反应 甲基汞（MeHg）。 MeHg 是一种理想的模型化学品，因为它具有强烈的公共卫生意义，有 已知接触甲基汞的人类和啮齿类动物存在表型差异，并且甲基汞不会造成 DNA 损伤，因此 独立影响 DNA 甲基化。我的职业发展目标是整合统计方面的新培训 遗传学与我在环境表观遗传学方面的背景进行机械和 可转化为人类。我将利用两只近交小鼠之间的经典 F2 杂交设计 菌株中，一种对甲基汞神经毒性敏感（CAST/EiJ），一种对甲基汞神经毒性具有抗性（C57BL/6J）。 F1代杂交小鼠是 通过亲本品系之间的相互杂交产生，以及通过将 F1 小鼠与相反品系杂交而产生 F2 杂交小鼠 血统。 F1 小鼠的基因型是相​​同的。 F2 小鼠基因型不同，但不携带 DNA 序列 F1 小鼠中也不存在。我将测量 F1 和 F2 小鼠海马体中的 DNA 甲基化水平 并且在母亲饮食中没有发育接触环境相关剂量（500 ng/g）的甲基汞。 F1 暴露小鼠与对照小鼠的 DNA 甲基化差异将代表环境影响；超变量 F1 对照小鼠中的 DNA 甲基化将代表随机效应。预测DNA的基因序列变异 F2对照小鼠中的甲基化将代表遗传效应；预测差异的序列变异 F2暴露与对照中的甲基化将代表基因-环境相互作用。这些结果将提供 深入了解甲基汞神经毒性个体间差异的原因。至关重要的是，这项工作将改善我们的 DNA 甲基化对毒物反应的机制理解。 ！ ！