The role of H3K36 methyltransferases on non-CpG methylation patterning in the mammalian brain

项目摘要： 人类遗传学研究已经将自闭症和相关的神经发育障碍（NDD）与自闭症的破坏联系起来。 编码表观遗传因子的基因。虽然这些基因的突变可以影响不止一种途径， 对于ASD，确定ASD遗传原因的共同分子途径可以提供对以下方面的了解： 广泛适用的治疗方法。我们实验室最近的证据表明，一种神经元特异性形式的DNA 甲基化是一种共有的表观遗传修饰，在ASD相关的神经发育疾病中被破坏。 虽然DNA甲基化传统上被认为只发生在哺乳动物细胞中的CpG背景下， 在由DNMT3A建立的非CpG环境中，神经元独特地富集甲基化。这种非CpG 甲基化主要发生在CA二核苷酸（mCA）处，并且对于适当的神经元发育是关键的， 功能虽然mCA在调节神经元基因表达中起重要作用，但尚不清楚mCA如何调节神经元基因表达。 mCA景观是忠实地建立在整个神经元基因组，以及是否额外的NDD涉及 mCA的破坏。最近在神经系统外的研究表明，组蛋白修饰可能 在指导DNMT 3A介导的DNA甲基化中发挥核心作用，但目前尚不清楚 这些组蛋白修饰如何影响整个神经元基因组中的DNMT3A和mCA。 有趣的是，H3K36组蛋白甲基转移酶的突变最近已经在ASD基因中被鉴定 问题研究此外，最近在神经系统外进行的研究表明，H3K36 甲基化募集DNMT3A并调节其活性。在这份提案中，我将确定H3K36如何破坏 甲基化介导的与DNMT3A的相互作用干扰了神经元基因组中mCA的关键模式 来驱动大脑功能障碍。在目标1中，我将破坏NDD相关的H3K36甲基转移酶，并测量如何 DNMT3A募集和mCA受到影响。这将定义组蛋白和DNA的潜在机制 修饰动力学调节神经元转录，并建立我们的基本理解， mCA的破坏导致疾病。在目标2中，我将探索H3K36二甲基酶NSD 1的缺失如何导致 通过在异质性临床研究中观察到的共享神经元染色质病理学导致神经元基因失调 ASD综合征我将使用基因组方法来研究如何改变DNA甲基化作为NSD 1的结果， 缺失影响增强子活性以驱动神经系统功能障碍和疾病中的转录失调。 该分析将开始以识别跨常见分子的关键下游染色质相关因子。 参与ASD的多种遗传原因的途径，以提供对功能性细胞结果的深入了解， 广泛适用的治疗方法。

Project Summary: Human genetic studies have linked autism and related neurodevelopmental disorders (NDD) to disruption of genes encoding epigenetic factors. While mutations in these genes can affect more than one pathway that leads to ASD, identification of a common molecular pathway across genetic causes of ASD can provide insight into broadly applicable therapies. Recent evidence from our laboratory suggests that a neuronal-specific form of DNA methylation is a shared epigenetic modification that is disrupted in ASD-associated neurodevelopmental disease. Though DNA methylation is classically considered to only occur in mammalian cells in the CpG context, neurons are uniquely enriched for methylation in non-CpG contexts established by DNMT3A. This non-CpG methylation primarily occurs at CA dinucleotides (mCA) and is critical for proper neuronal development and function. Though mCA plays an important role in regulating neuronal gene expression, it is not known how the mCA landscape is faithfully established across the neuronal genome, and whether additional NDDs involve disruption of mCA. Recent studies outside the nervous system have suggested that histone modifications may play a central role in directing DNMT3A-mediated DNA methylation across the genome, but it is not known to how these histone modifications influence DNMT3A and mCA throughout the neuronal genome. Intriguingly, mutations in H3K36 histone methyltransferases have been recently identified in ASD gene studies. Additionally, recent studies conducted outside the nervous system have suggested that H3K36 methylation recruits DNMT3A and regulates its activity. In this proposal, I will determine how disruption of H3K36 methylation-mediated interactions with DNMT3A disturbs critical patterns of mCA across the neuronal genome to drive brain dysfunction. In Aim 1, I will disrupt NDD-relevant H3K36 methyltransferases and measure how DNMT3A recruitment and mCA are affected. This will define the mechanisms underlying histone and DNA modification dynamics on regulating neuronal transcription and building our basic understanding of how disruption of mCA drives disease. In Aim 2, I will explore how loss of H3K36 dimethylase NSD1 causes dysregulation of neuronal genes via shared neuronal chromatin pathology observed across heterogenous clinical syndromes of ASD. I will use genomic approaches to examine how altered DNA methylation as a result of NSD1 loss affects enhancer activity to drive transcriptional dysregulation in nervous system dysfunction and disease. This analysis will begin to identify key downstream chromatin associated factors across a common molecular pathway involved in multiple genetic causes of ASD to provide insight into functional cellular outcomes and broadly applicable therapies.