Defining the Epigenetic Architecture Associated with Early-Life Stress

描述(申请人提供)：精神健康障碍的遗传基础非常复杂，涉及风险基因、环境和经验因素之间的多方面相互作用。众所周知，不良的早期生活事件使人在晚年更容易受到精神疾病的影响。然而，环境因素与神经系统遗传程序相互作用的表观遗传机制仍然知之甚少。这部分是由于神经细胞类型的复杂异质性和现有技术的局限性。在这里，我们建议用概念和技术创新的方法来研究早期生命应激引起的表观遗传修饰，如DNA甲基化和染色质组织。我们计划通过直接对甲基化的DNA进行测序，并通过直接检测甲基-CpG结合蛋白(MBP)与甲基化的DNA的动态关联来定位应激诱导的DNA甲基化变化。为了实现这一目标，我们将产生两个转基因小鼠品系：一个品系以空间和时间控制的方式表达生物素连接酶(Bira)和GFP；另一个品系携带标记有生物素化信号序列的内源MBP。在这两个小鼠品系的后代中，MBP将在确定的GFP阳性神经元群体中被特异性生物素化。在对这些转基因小鼠进行实验性治疗后，将通过高通量测序MeDIP-SEQ和BioMBP-CHIP-SEQ来定位特定神经元群体中的全基因组DNA甲基化位点。此外，与每个MBP相关的染色质复合体将通过系统的质谱学生物MBP-CHIP-MS/MS进行表征，以研究表观遗传修饰的分子机制。通过结合基因组和蛋白质组的方法，我们希望深入了解早期生活应激与易感基因相互作用并赋予精神疾病风险的表观遗传学机制。我们拟议的研究还将使我们能够更好地了解精神健康障碍的根本原因，并为改进诊断和干预提供必要的基础。 公共卫生相关性：这项建议的目标是开发一种创新的战略，以调查环境因素(如早期生活应激)与遗传学相互作用的表观遗传机制，以及这些相互作用如何增加精神疾病的风险。我们计划创造新的转基因小鼠系来标记甲基-CpG结合蛋白，特别是在特定的神经元群体中。然后，我们将用基因组和蛋白质组的方法研究与大脑中的环境线索相关的表观遗传学变化。这项拟议的研究不仅对于理解经验依赖型大脑发育的表观遗传控制，而且对于理解精神障碍的分子和细胞基础都具有重要意义。人们很容易争辩说，我们的研究可能确定干预和/或预防精神疾病的潜在分子、细胞和电路目标。

DESCRIPTION (provided by applicant): The genetic underpinnings of mental health disorders are highly complex, involving multifaceted interactions between risk genes, the environment, and experiential factors. It is well known that adverse early life events confer significantly greater susceptibility to psychiatric conditions in later life. However, the epigenetic mechanisms by which environmental factors interact with genetic programs in the nervous system remain poorly understood. This is partially due to the complex heterogeneity of neuronal cell types and the limitations of existing techniques. Here we propose to investigate the epigenetic modifications such as DNA methylation and chromatin organization induced by early-life stress with conceptually and technically innovative approaches. We plan to map the stress-induced DNA methylation changes by directly sequencing the methylated DNA and by directly examining the dynamic association of methyl- CpG binding proteins (MBPs) with methylated DNA. To achieve this, we will generate two transgenic mouse lines: one line expresses biotin ligase (BirA) and GFP in a spatially and temporally controlled manner; while the other line carries an endogenous MBP tagged with a biotinylation signal sequence. In the resulting progeny of these two mouse lines, MBP will be specifically biotinylated in a defined population of GFP-positive neurons. Following experimental treatment of these transgenic mice, the genome-wide DNA methylation loci in specific neuronal populations will be mapped by high throughput sequencing MeDIP-seq and bioMBP-ChIP-seq. In addition, the chromatin complexes associated with each MBP will be characterized by systematic mass spectrometry bioMBP-ChIP-MS/MS to investigate the molecular mechanisms underlying epigenetic modifications. With the combined genomic and proteomic approaches, we hope to gain an insight into the epigenetic mechanisms through which early-life stress interacts with susceptibility genes and confers risks to mental illness. Our proposed study will also allow greater understanding of the underlying causes of mental health disorders and provide the necessary foundation for improved diagnosis and interventions. PUBLIC HEALTH RELEVANCE: The goal of this proposal is to develop an innovative strategy to investigate the epigenetic mechanisms by which environmental factors such as early life stress interact with genetics, and how these interactions increase the risk of mental illness. We plan to generate novel genetically modified mouse lines to tag methyl-CpG binding proteins specifically in a defined population of neurons. We will then investigate the epigenetic changes associated with environmental cues in the brain with both genomic and proteomic approaches. The proposed studies will be of significance not only in understanding the epigenetic control of experience-dependent brain development, but also in understanding the molecular and cellular basis of mental disorders. It is tempting to argue that our research may identify potential molecular, cellular, and circuit targets to intervene and/or prevent mental illness.