Exposure-altered gene expression in five candidate imprinted loci for adult disease

成人疾病的五个候选印迹基因座中暴露改变的基因表达

• 批准号: 9106621
• 负责人: Zhibin Wang
• 金额: $ 34.89万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9106621
• 关键词: 129 Mouse; Address; Adult; Affect; Alleles; Animal Model; Animals; Barker Hypothesis; Behavior Disorders; Binding; Binding Sites; Cell Differentiation process; ChIP-seq; Charcot-Marie-Tooth Disease; Control Locus; DNA Methylation; DNA Modification Methylases; Data; Development; Diabetes Mellitus; Disease; Embryo; Endocrine Disruptors; Environmental Exposure; Environmental Risk Factor; Epigenetic Process; Epilepsy; Exposure to; Famines; Female; Fetal Liver; Fetus; Gene Expression; Genes; Genome; Genomic Imprinting; Growth and Development function; Histone Code; Histones; Human; Hunger; Individual; Knock-out; Knowledge; Life; Link; Location; Methylation; Mus; Mutate; Neurologic; Parents; Parkinson Disease; Partner in relationship; Pathogenesis; Pattern; Perinatal Exposure; Play; Predisposition; Prevention strategy; Process; Regulation; Resolution; Risk; Role; Schizophrenia; Shapes; Staging; Survivors; Testing; Tissue-Specific Gene Expression; Tissues; Toxic Environmental Substances; Toxicant exposure; base; bisphenol A; developmental plasticity; embryonic stem cell; fetal bisphenol-A exposure; histone methylation; histone modification; imprint; insight; male; methylation pattern; methylome; mouse genome; nervous system disorder; neuron development; novel; novel strategies; prenatal; promoter; public health relevance; response; toxicant

 DESCRIPTION (provided by applicant): Increasing evidence from studies of animals and of individuals who suffered from the Dutch Hunger Winter of 1944-45 supports the concept that environmental exposure of early embryos causes increased risk of development of disease in adulthood (Barker hypothesis). For example, exposure of mouse embryos to the endocrine disrupting chemical Bisphenol A (BPA) is known to cause many disorders, including neurological/behavioral disorders. Genomic imprinting (an epigenetic process to control parent-origin-specific expression of genes) has been theorized as the major determinant of these effects. Methylation of Igf2 differentially-methylated-region (DMR; a hallmark of imprinting) is persistently changed in individuals surviving the Dutch famine. Our understanding of the mechanism(s) underlying the "Barker hypothesis" has been hampered by focusing only on a few imprinted loci (i.e. Igf2). However, it is unlikely that all 20 "Barker diseases" are due solely to changes in Igf2 expression; particularly as many "Barker diseases" have no association with known imprinted genes. Using two novel approaches (so-called NORED and Tag-mosaicity), which allow one to analyze base-resolution methylomes of DNA methyltransferase (DNMT) knockout (KO) embryonic stem cells (ESCs), we have successfully identified 20 novel DMRs representing 17 `candidate' imprinted loci. Intriguingly, five of these 17 putative imprinted loci are linked to neurological disorders in humans. Further studies are needed to confirm that these putative loci contain imprinted genes and to determine whether (and then how) environmental exposure-altered DMRs change expression of these putatively imprinted genes within these loci, thereby contributing to the pathogenesis of "Barker diseases." To this end, we confirmed at least one locus (i.e., D2hgdh) via revealing its allelic methylation patterns and found that alleli methylation of five DMRs dictates the binding of insulator CTCF for potentially effecting histone modifications of imprinted genes. Furthermore, fetal exposure of BPA altered multiple DMRs including selected DMRs. Based on our exciting preliminary data, we hypothesized that DMRs dictate the allele-specific binding of CTCF and CTCF insulation subsequently controls the distinct histone modifications at promoters of different imprinted genes in five loci for regulatio. Lastly, BPA exposure-altered DMRs in these loci change gene expression, thereby contributing to the pathogeneses of neurological disorders. We will test our hypothesis through three complementary aims: SA1, Determine whether the putative DMRs dynamically alter gene expression in a tissue-specific manner. SA2, Determine the mechanisms of imprinting of five novel loci. SA3, Determine whether BPA-induced alterations in novel DMRs result in altered tissue-specific gene expression during development. The results of these studies should elucidate how putatively imprinted genes from five `candidate' loci contribute to developmental plasticity during normal growth and development or under environmental exposure-altered conditions and inform the development of prevention strategies to protect the unborn fetus.

 描述（由申请人提供）：对遭受 1944-45 年荷兰饥饿冬季的动物和个人的研究越来越多的证据支持这样的观点，即早期胚胎的环境暴露会导致成年后患疾病的风险增加（巴克假说）。例如，已知小鼠胚胎接触内分泌干扰化学物质双酚 A (BPA) 会导致许多疾病，包括神经/行为障碍。基因组印记（控制亲本来源特异性基因表达的表观遗传过程）已被理论化为这些效应的主要决定因素。在荷兰饥荒中幸存下来的个体中，Igf2 差异甲基化区域（DMR；印记的标志）的甲基化持续发生变化。我们对“巴克假说”背后机制的理解因仅关注少数印记基因座（即 Igf2）而受到阻碍。然而，所有 20 种“巴克病”不太可能仅仅归因于 Igf2 表达的变化；特别是许多“巴克病”与已知的印记基因没有关联。使用两种新方法（所谓的 NORED 和 Tag-mosaicity），可以分析 DNA 甲基转移酶 (DNMT) 敲除 (KO) 胚胎干细胞 (ESC) 的碱基分辨率甲基化组，我们成功鉴定了代表 17 个“候选”印记位点的 20 个新 DMR。有趣的是，这 17 个假定的印迹基因座中有 5 个与人类神经系统疾病有关。需要进一步的研究来证实这些假定的基因座包含印记基因，并确定环境暴露改变的 DMR 是否（以及如何）改变这些基因座内这些假定的印记基因的表达，从而导致“巴克病”的发病机制。为此，我们通过揭示其等位基因甲基化模式确认了至少一个基因座（即 D2hgdh），并发现五个 DMR 的等位基因甲基化决定了绝缘子 CTCF 的结合，从而可能影响印记基因的组蛋白修饰。此外，胎儿接触 BPA 会改变多个 DMR，包括选定的 DMR。基于我们令人兴奋的初步数据，我们假设 DMR 决定 CTCF 的等位基因特异性结合，并且 CTCF 绝缘随后控制五个位点中不同印记基因启动子处的不同组蛋白修饰以进行调节。最后，BPA 暴露改变了这些位点中的 DMR，从而改变了基因表达，从而导致了神经系统疾病的发病机制。我们将通过三个互补的目标来检验我们的假设： SA1，确定假定的 DMR 是否以组织特异性方式动态改变基因表达。 SA2，确定五个新基因座的印记机制。 SA3，确定 BPA 诱导的新型 DMR 改变是否会导致发育过程中组织特异性基因表达的改变。这些研究的结果应阐明五个“候选”基因座的推定印记基因如何在正常生长和发育期间或在环境暴露改变的条件下促进发育可塑性，并为保护未出生胎儿的预防策略的制定提供信息。