To define the identity of telomerase/TERT positive cells and functional characterization of TERT in neuronal stem cell and brain tumors

端粒酶是延长端粒的酶复合物，由两种基本组分组成的催化核心组成：RNA亚基TERC和蛋白质催化亚基TERT。TERT是一种结合TERC并合成端粒的逆转录酶。除了其在延长端粒中的既定作用外，对毛囊干细胞的研究表明，TERT被募集到启动子染色质中以调节参与Wnt信号通路的基因。端粒酶在干/祖细胞中表达，并且在大多数人类肿瘤中上调。然而，在组织内表达Tert的细胞类型的确切身份尚未明确定义，这限制了我们对端粒酶功能的理解。为了了解端粒酶在神经干细胞群中的功能，特别是在海马和脑室下区的大脑，我将使用新的Tert-GFP和Tert-TdTomato基因敲入报告小鼠模型。这将允许定义在正常脑和脑胶质瘤癌症如星形细胞瘤中表达Tert的细胞的身份。将通过在神经发育期间、在成人脑和脑肿瘤中在体内小鼠干/前体细胞中Tert基因的条件性和急性缺失来确定TERT所起的功能作用。为了研究TERT影响干细胞功能和癌症发展的机制，我将采用ChIP-Seq，一种基于测序的技术来确定端粒酶与启动子序列的染色质关联的全球模式。结合RNA表达分析，这些研究将揭示端粒酶在脑和某些脑肿瘤中调控基因表达的模式，这些目标的成功完成将增强我们对干细胞在神经发生、损伤反应和脑肿瘤发生机制中的功能的理解。

The telomerase, the enzyme complex that elongates telomeres, is comprised of a catalytic core consisting of two essential components: an RNA subunit, TERC, and a protein catalytical subunit, TERT. TERT is a reverse transcriptase that binds TERC and synthesizes telomeres. In addition to its established role in extending telomeres, studies on hair follicle stem cells showed that TERT is recruited to promoter chromatin to regulate genes involved in the Wnt signaling pathway. The telomerase is expressed in stem/progenitor cells and is upregulated in the majority of human tumors. However, the exact identity of the cell types that express Tert within a tissue is not clearly defined, which has limited our understanding of telomerase function. To understand telomerase function in neuronal stem cell populations especially in hippocampus and subventricular region of the brain, I will use novel Tert-GFP and Tert-TdTomato knock-in reporter mouse models. This will allow defining the identity of cells expressing Tert in normal brain and in brain glioma cancers such as astrocytomas. The functional role served by TERT will be determined through conditional and acute deletion of the Tert gene in mouse stem/precursor cells in vivo during neural development, in adult brain and in brain tumors. To study the mechanism by which TERT affects stem cell function and cancer development, I will employ ChIP-Seq, a sequencing-based technology to determine the global pattern of chromatin association of telomerase with promoter sequences. Together with RNA expression analyses, these studies will reveal the pattern of genes whose expression telomerase modulates in the brain and in certain brain tumors.Successful completion of these aims will enhance our understanding of stem cell function in neurogenesis, response to injury and mechanisms underlying brain tumorigenesis.