Epigenetic Mechanisms of Chronic Stress Action

项目概要： 这是一个新的R 01授权的修订版本，其特征是在基因组中诱导的稳定的表观遗传变化。 小鼠边缘脑区域对早期生活压力（ELS）的反应，然后增加个体的 对后续应力的敏感性。这项工作在过去十年中得到了一个 然而，NIMH Conte中心现在已经“日落”-它无法更新-因此，这个新的 建议继续这一原始研究路线。我们的创新假设是ELS诱导稳定的 “染色质疤痕”，驱动基因表达的长期变化，然后介导下游变化 细胞和电路功能以及最终对成年期慢性压力的行为反应。我们集中 基于其在大脑奖励和动机中的核心作用以及实证研究结果， 它在控制压力敏感性方面的核心作用。我们利用开放式的，无偏见的蛋白质组学和下一个- 第二代测序方法，首先确定最强大的和显着的推定染色质疤痕， 以细胞类型特异性方式检测NAc，然后在分子、细胞和免疫学水平上表征这些机制。 行为水平。重要的是，我们只研究那些在死后NAc中被验证的机制。 抑郁的人类一个主要的焦点是H3 K79 me 2（组蛋白H3的Lys 79的二甲基化）， 这是ELS在雄性和雌性小鼠NAc中引起的最显著的组蛋白修饰。的 控制H3 K79 me 2的甲基转移酶（DOT 1 L）和脱甲基酶（KDM 2B）都被 ELS，D2型中型棘神经元（MSN）特异性效应。双向病毒介导的操纵 DOT 1 L或KDM 2B在雄性和雌性小鼠的D2 NAc MSN中的选择性确定了这些基因所起的作用。 基于快速行为筛选的酶介导ELS增加应激易感性的能力 测定。我们现在将压力敏感性的测量扩展到许多更复杂的行为， 具有更大的翻译潜力的程序，并测试DOT 1 L抑制剂的能力，现在在临床试验中， 某些癌症，以逆转全身给药后ELS诱导的应激易感性，进一步促进 所提议研究的转化潜力。同样，我们已经通过RNAseq表明，DOT 1 L D2 MSN中的过表达模拟了ELS在该细胞中诱导的大部分基因表达变化 类型，而DOT 1 L击倒阻止ELS动作。我们现在将绘制H3 K79 me 2富集全基因组， CUT&RUNseq的D2 MSN，以鉴定ELS改变表达的基因网络， 组蛋白标记。我们还将生成更完整的开放式蛋白质组和转录组数据集， 表征ELS在NAc中诱导的其他假定染色质瘢痕。大量的初步数据， 例如，暗示H3 K27 me 1是一种突出的染色质恐慌，在雄性小鼠的D1 MSN中占主导地位 只.总之，这项工作将表征新的机制，驱动持续的状态增强的压力 易感性，并提供洞察到新的方法来扭转这种易感性在成年期。

PROJECT SUMMARY: This is a revised version of a new R01 grant that characterizes stable epigenetic changes that are induced in mouse limbic brain regions in response to early life stress (ELS) which then increase an individual's susceptibility to subsequent stress for a lifetime. This work has been supported over the past ten years by an NIMH Conte Center, however, that Center has now “sun-setted”—it cannot be renewed—hence, this new proposal to continue this original line of research. Our innovative hypothesis is that ELS induces stable “chromatin scars” that drive long-lived changes in gene expression, which then mediate downstream changes in cell and circuit function and ultimately behavioral responses to chronic stress in adulthood. We concentrate on nucleus accumbens (NAc) based on its central role in brain reward and motivation and on empirical findings of its central role in controlling stress susceptibility. We utilize open-ended, unbiased proteomic and next- generation sequencing approaches to first identify the most robust and significant putative chromatin scars in NAc in a cell-type-specific manner and to then characterize those mechanisms at the molecular, cellular, and behavioral levels. Importantly, we investigate only those mechanisms that are validated in postmortem NAc of depressed humans. One major focus is H3K79me2 (dimethylation of Lys79 of histone H3), the induction of which is the most significant histone modification caused by ELS in NAc of both male and female mice. The methyltransferase (DOT1L) and demethylase (KDM2B) that control H3K79me2 are both induced in NAc by ELS, effects specific to D2-type medium spiny neurons (MSNs). Bidirectional viral-mediated manipulation of DOT1L or KDM2B selectively in D2 NAc MSNs of male and female mice establishes the role played by these enzymes in mediating the ability of ELS to increase stress susceptibility based on rapid behavioral screening assays. We will now extend measures of stress susceptibility to numerous, more sophisticated behavioral procedures with greater translational potential, and test the ability of a DOT1L inhibitor, now in clinical trials for certain cancers, to reverse ELS-induced stress susceptibility upon systemic administration, further promoting the translational potential of the proposed research. As well, we have shown by RNAseq that DOT1L overexpression in D2 MSNs mimics a large portion of gene expression changes induced by ELS in this cell type, while DOT1L knockdown blocks ELS action. We will now map H3K79me2 enrichment genome-wide in D2 MSNs by CUT&RUNseq to identify networks of genes whose altered expression by ELS is mediated by this histone mark. We will also generate more complete open-ended proteomic and transcriptomic datasets and characterize additional putative chromatin scars induced in NAc by ELS. Substantial preliminary data, for example, implicate H3K27me1 as a prominent chromatin scare that predominates in D1 MSNs of male mice only. Together, this work will characterize novel mechanisms that drive a persisting state of enhanced stress susceptibility and offer insight into new ways of reversing such susceptibility in adulthood.