Neurog1介导H3K4me3/H3K27me3表观遗传修饰对小鼠海马神经干细胞调控作用及机制研究

三甲基化修饰的H3组蛋白第4和第27位赖氨酸（H3K4me3/H3K27me3）调控多种干细胞生物进程，但其在神经干细胞（NSCs）中的作用及机制缺乏研究。预实验发现H3K4me3/H3K27me3调控小鼠海马NSCs增殖分化，并可影响神经发生关键调节基因Neurog1表达。提示H3K4me3/H3K27me3可能通过影响Neurog1活性，进而调控NSCs。本研究通过改变H3K4me3或H3K27me3修饰水平，观察细胞增殖分化变化，明确其在NSCs中的作用。应用μChIP-seq结合激光捕获显微切割，测序分析H3K4me3/H3K27me3，筛选确认Neurog1为靶基因，并进行验证，明确“H3K4me3/H3K27me3-Neurog1-NSCs调控”关系网络，阐明其作用机制。通过本研究实施有望揭示一种新的小鼠海马神经发生表观遗传调控机制，为神经系统疾病治疗提供新思路及潜在治疗靶点。

Histone modification, as one of the epigenetic regulations, participates in orchestrating multiple biological processes, like mammalian embryo development and DNA repair. Histone H3 lysine 4 trimethylation (H3K4me3) and histone H3 lysine 27 trimethylation (H3K27me3) are reported to play an important role in regulating the bio-processes of different species of stem cells. However, little is known about their effects on neural stem cells (NSCs). Our previous research showed that H3K4me3 and H3K27me3 bared cell-type specific distributions, respectively. Robust enrichment of H3K4me3 was observed in the subgranular zone (SGZ), while high levels of H3K27me3 were mainly presented in the granule cell layer (GCL). Generally, in mouse dentate gyrus (DG), neurogenesis occurs in SGZ while GCL mainly contains granule cells which are a type of mature neuron. We also found that the number of cells with high levels of H3K4me3 was decreased during mouse hippocampus development; on the contrary, cells with high levels of H3K27me3 were gradually increased with the development. Furthermore, both H3K4me3 and H3K27me3 have impacts on proliferation and differentiation of NSCs. Moreover, H3K4me3 and H3K27me3 also can affect the expression of Neurog1 which is the key gene of regulation and control in NSCs proliferation and differentiation. These phenomena prompted that epigenetic H3K4me3 and H3K27me3 might act as molecular “switch” to regulate proliferation and differentiation of NSCs through an effect on the Neurog1 gene activation in the mouse hippocampus. In this study, we plan to modulate the levels of H3K4me3 or H3K27me3 by editing the expressions of lysine demethylases (KDM), to detect the proliferation and differentiation changes of NSCs, and then clearly understand the function of H3K4me3 and H3K27me3 in NSCs. Previously, direct measurements of chromatin states have been hindered by technical difficulties in profiling histone modifications from a small amount of cells. Thus, colleagues of our research group successfully developed a micro-scale chromatin immunoprecipitation and sequencing (μChIP-seq) method, which could be used to measure histone modifications from a small amount of cells. The technique will be further applied in systematically profiling genome-wide dynamic changes of H3K4me3 and H3K27me3 at different stages of hippocampus development in SGZ and GCL. Screen out and validate that H3K4me3/H3K27me3 affect proliferation and differentiation of NSCs by regulating the expression of Neurog1. Our study may illustrate a novel epigenetic regulatory mechanism in the regulation of NSCs and provide a new strategy and a novel potential target for the treatment of nervous system disorders.