Epigenetic roles of DNA adenine methylation in stress response

项目摘要 近年来，细菌基因组中富集的DNA腺嘌呤--N6-甲基腺嘌呤（6 mA）的甲基化， 在果蝇和哺乳动物基因组中发现。6 mA在胚胎发育过程中动态调节 并可能在调节基因和转座子表达方面发挥表观遗传作用。然而，6 mA在 哺乳动物的大脑仍然是未知的。我们的初步研究强调了6 mA及其分子 是果蝇大脑正常神经发育所必需的。初步数据一致 在出生后的小鼠脑和人胚状体中显示了6 mA的动态调节 发展环境慢性应激可引起小鼠脑内6 mA的动态变化， 与抑郁症有关。表观遗传改变导致的出生后脑发育的复杂变化 可以解释压力反应的改变和许多精神疾病， 这些过程仍不清楚。6 mA及其假定机制在脑发育中的作用， 压力反应使它们成为这些相关过程中一个有吸引力的因果机制。不过有 几乎没有研究精确地检查脑区域特异性和神经元细胞类型特异性6 mA动力学， 它们在大脑发育中的表观遗传作用。此外，缺乏关于6 mA的知识 哺乳动物基因组中的甲基转移酶（“写入者”）及其结合蛋白（“读取者”）阻碍了我们的进一步研究。 了解它们在大脑发育和应激反应中的精确表观遗传作用。基于这项工作， 我们假设6 mA及其分子机制在哺乳动物大脑发育中起着至关重要的作用， 它们的失调会导致大脑中应激反应的改变。我们将首先使用已建立的全基因组 6 mA映射工具，用于识别脑区域特异性和细胞类型特异性差异6 mA甲基化区域 在小鼠出生后发育期间检测D 6AMR，并将这些数据与全局转录组分析相关联， 精确定位6 mA在这些过程中的详细和精确的表观遗传作用（目标1）。我们将定义6 mA 假定的甲基转移酶“作家”在哺乳动物基因组中，并调节其表达在体内测试 它们在兴奋性和抑制性神经元中通过6 mA调节的发育相关应激反应中的作用 (Aim 2）。我们的数据表明，6 mA可能拮抗或招募缺氧诱导因子-1（HIF 1）， 果蝇Polycomb（Pc）。基于这些结果，我们将确定Hif 1和 哺乳动物6 mA Polycomb蛋白及其在神经元发育相关应激反应中的作用 水平（目标3）。这项研究的结果将提供新的机制的见解6 mA在大脑发育 及其相关的应激反应，并可能发现新的具有重要临床意义的分子靶点， 精神疾病的翻译影响。

Project Summary Methylation on the DNA adenine, N6-methyladenine (6mA) that enriched in the bacteria genome, was recently found in the Drosophila and mammalian genomes. 6mA is dynamically regulated during embryonic development and could play epigenetic roles in regulating gene and transposon expression. However, the roles of 6mA in mammalian brains remain largely unknown. Our preliminary study highlights that 6mA, and its molecular machinery, is required for proper neurodevelopment in Drosophila brains. Preliminary data consistently demonstrated a dynamic regulation of 6mA during postnatal mouse brain and human embryoid body development. Environmental chronic stress induces dynamic alteration of 6mA in mouse brains, in the loci highly correlated with depression. The complex changes in postnatal brain development due to the epigenetic alteration could account for the altered stress response and many mental illnesses, the molecular mechanisms connecting these processes remain unclear. The involvement of 6mA and its putative machinery in brain development and stress response makes them an attractive causal mechanism in these connected processes. However, there is little research precisely examining the brain region-specific and neuronal cell type-specific 6mA dynamics and their epigenetic roles during brain development. Furthermore, the lack of knowledge regarding the 6mA methyltransferases (“writers”) and its binding proteins (“readers”) in the mammalian genome hinders our further understanding of their precise epigenetic roles in brain development and stress response. Based on this work, we hypothesize that 6mA and its molecular machinery play crucial roles in mammalian brain development, and their dysregulation contributes to altered stress response in the brain. We will first use established genome-wide 6mA mapping tools to identify brain region-specific and cell type-specific differentially 6mA methylated regions (D6AMRs) during mouse postnatal development and correlate these data with global transcriptome analysis to pinpoint the detailed and precise epigenetic roles of 6mA in these processes (Aim 1). We will then define 6mA putative methyltransferases “writers” in the mammalian genome and modulate their expression in vivo to test their roles in development-related stress response through 6mA regulation in excitatory and inhibitory neurons (Aim 2). Our data suggest 6mA could potentially antagonize or recruit hypoxia-induced factor-1 (Hif1) and Drosophila Polycomb (Pc), respectively. Based on these results, we will determine the interplay of Hif1 and mammalian Polycomb proteins with 6mA and their roles in development-related stress response at the neuronal levels as well (Aim 3). Findings of this study will provide novel mechanistic insights of 6mA in brain development and its related stress response and are likely to discover new molecular targets with important clinical and translational implications in mental illnesses.