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

基本信息

批准号：
10452549
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
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-08-15 至 2024-07-31
项目状态：
已结题

项目摘要

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. ! !

项目摘要环境有毒物质暴露与DNA甲基化的变化或化学修饰与DNA相关调节基因表达，但是这些相关性的基础机制尚不清楚。 DNA甲基化在遗传上相同的个体可能会有所不同，从而使不同的表型从相同的基因型发展出来曝光后。这些结果表明对化学物质的特定细胞反应，导致环境表型的差异。此外，未暴露在遗传上相同的个体显示DNA的变异性甲基化，表明某些差异是随机的（即概率）。在遗传上不同的个体中，在不存在和存在化学的情况下，DNA甲基化模式与基因型高度相关暴露，表明某些DNA甲基化在遗传控制下，并且一些DNA甲基化对化学物质的反应比其他基因型发生的更多（基因环境相互作用）。在这里，我会的测试中心假设，即这四个来源分别解释了总DNA甲基化的相等比例在基因型不同的小鼠中的反应，发育暴露于模型化学物质，重金属甲基马克（MEHG）。 MEHG是一种理想的模型化学物质，因为它具有强烈的公共卫生关注，有暴露的人和啮齿动物和MEHG的已知表型差异不会引起DNA损伤，这独立影响DNA甲基化。我的职业发展目标是将新培训整合到统计中具有我的环境表观遗传学背景的遗传学，可以进行机械性和可以翻译成人类。我将利用两只近交鼠标之间的经典F2互变设计菌株，一种易感性（cast/eij），一种抗性（C57BL/6J）对MEHG神经毒性。 F1杂种小鼠是通过与相反的F1小鼠交叉F1 parentage。 F1小鼠在基因型上是相同的。 F2小鼠在基因型上不同，但没有DNA序列 F1小鼠也不存在。我将测量来自F1和F2小鼠的海马中的DNA甲基化水平并且没有发育中的孕产妇饮食中MEHG与环境相关的剂量（500 ng/g）。 F1暴露与对照小鼠的DNA甲基化差异将代表环境影响；高变量 F1对照小鼠中的DNA甲基化将代表随机作用。预测DNA的遗传序列变异 F2对照小鼠中的甲基化将代表遗传作用。预测差异的序列变体 F2暴露与控制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MEHG神经毒性中个体差异的原因。至关重要的是，这项工作将改善我们的对DNA甲基化对毒物的反应的机械理解。呢呢