Understanding the role of DNA methylation dynamics at Bdnf during fear conditioning

项目总结/摘要 创伤后应激障碍（PTSD）部分是由大脑中异常的恐惧巩固所驱动的。 神经营养因子和染色质动力学的信号传导对于这种记忆巩固至关重要。信令 脑源性神经营养因子（BDNF）及其主要受体酪氨酸受体激酶B（Trk B）， 在巩固杏仁核中的恐惧中起着重要作用。事实证明，两者 杏仁核特异性敲除Bdnf和阻断Bdnf-TrkB信号传导干扰巩固。因此 突触前转录以及突触后信号传导对其功能都是至关重要的。此外，研究 已经证明了DNA甲基化（5-mC）水平与DNA甲基化的差异转录之间的相关性。 这表明表观遗传修饰正在驱动Bdnf基因的转录调控过程 在恐惧记忆巩固过程中我们的目的是分析DNA羟甲基化（5-hmC）水平在BDNF和 使用Cas9-Tet 1构建体来研究定点表观遗传之间的因果关系， 调节和恐惧巩固。 与其他组织相比，神经组织具有非常高水平的5-hmC。规范上，5-mC 已被认为是一个相对稳定的表观遗传标记，描绘组织特异性启动子激活。 然而，两个重要证据证明了5 mC监管对恐惧的重要性 巩固：动态DNA甲基化是必要的恐惧巩固，和操作Tet 1 一种负责将5-mC转化为5-hmC的酶干扰了情境恐惧 记忆我们假设5-hmC在恐惧巩固过程中会动态调节BDNF， 5-hmC的改变对于巩固恐惧记忆是必要的。在目标1中，我们将使用全基因组 和基因座特异性的方法来分析恐惧条件反射过程中Bdnf的5-hmC和5-mC。在目标2中， 在体外和行为小鼠中进行概念验证Cas9-Tet 1表观基因组工程实验，以及 我们将阐明BDNF内候选位点的动态5-hmC与恐惧巩固之间的关系。

Project Summary/Abstract   Post-Traumatic Stress Disorder (PTSD) is driven, in part, by aberrant fear consolidation in the brain. Signaling by neurotrophic factors and chromatin dynamics are crucial for this memory consolidation. Signaling between brain-derived neurotrophic factor (Bdnf) and its primary receptor, tyrosine-receptor kinase B (TrkB), plays an important role in the consolidation of fear in the amygdala. Indeed, it has been shown that both amygdala specific knockout of Bdnf and blockage of Bdnf-TrkB signaling interfere with consolidation. Thus both presynaptic transcription as well as post-synaptic signaling is crucial for its function. Furthermore, studies have demonstrated an associated between DNA methylation (5-mC) levels, and differential transcription of Bdnf, suggesting that epigenetic modifications are driving transcriptional regulatory processes at the Bdnf gene during fear memory consolidation. We aim to profile the DNA hydroxymethylation (5-hmC) levels at Bdnf and employ a Cas9-Tet1 construct to investigate the causal relationship between site-directed epigenetic modulation and fear consolidation. Neural tissues possess very high levels of 5-hmC, as compared to other tissues. Canonically, 5-mC has been considered to be a relatively stable epigenetic mark, delineating tissue-specific promoter activation. However, two important pieces of evidence have demonstrated the importance of 5-mC regulation for fear consolidation: dynamic DNA methylation is necessary for fear consolidation, and manipulation of the Tet1 enzyme, one enzyme responsible for the conversion of 5-mC to 5-hmC, interfered with contextual fear memory. We hypothesize that 5-hmC will dynamically regulate Bdnf during fear consolidation, and that these 5-hmC alterations will be necessary for the consolidation of fear memory. In aim 1 we will use genome-wide and locus-specific approaches to profile 5-hmC and 5-mC at Bdnf during fear conditioning. In aim 2 we will perform proof-of-concept Cas9-Tet1 epigenomic engineering experiments in vitro and in behaving mice, and we will elucidate the relationship between dynamic 5-hmC at candidate loci within Bdnf and fear consolidation.