成年哺乳动物脑内存在的神经干细胞增殖、分化为成熟的神经细胞并整合到神经回路中的过程称为神经发生。包括DNA甲基化在内的表观遗传学机制对神经干细胞和神经发生具有重要的调节作用。DNA 双加氧酶Tet蛋白家族能够介导DNA去甲基化，催化5-甲基胞嘧啶（5-mC）成为5-羟甲基胞嘧啶(5-hmC），该去甲基化过程在成体神经干细胞中的作用尚未见报道。本研究将以Tet1和Tet2基因敲除小鼠为模型，通过在体内和体外研究Tet1和Tet2基因敲除后成体神经干细胞和神经发生的改变，揭示5-hmC介导的表观遗传学途径对成体神经干细胞和神经发生的调控作用。本研究还将通过5-hmC的全基因组作图，Tet1和Tet2的染色质免疫沉淀测序（ChIP-seq）和RNA-seq，发现Tet1和Tet2在神经干细胞基因组中的结合位点和调控网络,揭示DNA去甲基化对神经干细胞和神经发生的调控机制。

Adult neurogenesis refers to the proliferation of neural stem cells, maturation and the integration of new born neurons into the neural circuits, which plays essential function in multiple normal biological processes and diseases. DNA methylation play important regulatory function in adult neural stem cells and neurogenesis. Tet1 and Tet2 could catalyze 5-methylcytosine (5-mC)into 5-hydroxymethylcytosine (5-hmC).The function of this demethylation in adult neural stem cells and adult neurogenesis is largely unknown. In the current proposal, we will study the regulatory roles of 5-hmC mediated epigenetic pathways in adult neural stem cells and adult neurogenesis in vitro and in vivo with Tet1 and Tet2 single and/or double knockout mice. Unitlizing our established technology, we will sequence 5-hmC at a genome-wide level， and also identify the binding sites and regulatory network in the genome through ChIP-seq and RNA-seq. Our proposed study will contribute to understand the function and mechanism of DNA demethylation in neural stem cells and adult neurogenesis.

成年哺乳动物脑内存在的神经干细胞增殖、分化为成熟的神经细胞并整合到神经回路中的过程称为神经发生。包括DNA 甲基化在内的表观遗传学机制对神经干细胞和神经发生具有重要的调节作用。DNA 双加氧酶Tet 蛋白家族能够介导DNA 去甲基化，催化5-甲基胞嘧啶（5-mC）成为5-羟甲基胞嘧啶(5-hmC），该去甲基化过程在成体神经干细胞中的作用尚未见报道。本课题通过体内和体外研究发现Tet2 基因敲除成年小鼠神经干细胞增殖能力增强，而Tet2敲除抑制成体神经干细胞的分化。Tet2敲除后成年神经干细胞DNA去甲基化水平明显降低。全基因组5hmC测序和RNA测序揭示了5hmC对基因表达的调控作用。进一步研究发现Tet2可以和转录因子FoxO3相互作用而发挥调控成体神经发生的作用。同时，我们还发现AD模型小鼠脑内DNA去甲基化的变化。