Regulation of human telomerase

摘要 我们的长期目标是破译端粒酶调控和端粒的分子机制 在发展过程中的平衡。端粒酶延长端粒，以补偿其在细胞分裂过程中的损失。 增殖它的调节对于人类衰老和癌症易感性以及许多与年龄相关的疾病至关重要。 退化性疾病编码人类端粒酶逆转录酶的TERT基因受到调控， 主要是在转录水平。它在多能干细胞中高度表达，但在细胞中被严格抑制。 大多数体细胞近年来关于端粒酶在肿瘤细胞中调控的研究进展极大地提高了我们对肿瘤细胞端粒酶活性的认识。 了解癌症发展过程中的TERT基因激活。然而，其抑制机制 在大多数分化细胞中的表达和在某些体细胞中的表达仍有待阐明。调控 发育和分化过程中的转录通常涉及远端元件和染色质重组。 我们先前报道内源性TERT基因嵌入在浓缩的染色质结构域中， 在体细胞中以组蛋白脱乙酰酶依赖的方式被严格抑制。识别远端调节 序列所需的建立抑制性染色质的TERT基因座，并了解其调控 在活体方面，我们的实验室在过去十年中开发了两个创新的技术平台。一是 重组酶介导的BAC靶向或RMBT方法，用于单拷贝BAC报告基因的靶向整合 插入特定的染色体位点这项技术与新的CRISPR介导的基因编辑一起， 我们在其基因组背景下研究TERT基因的远端调控元件。因此，我们 发现内含子2中的多态性串联DNA重复序列（VNTR2 - 1）作为TERT的增强子发挥作用 转录。此外，我们还设计了一个人源化的mTert等位基因（hmTert），用于研究人类特异性 小鼠端粒酶的调节。在下一个资助期内，我们计划使用这些工具，并专注于以下方面 三个方向：（1）通过VNTR2 - 1鉴定调控TERT基因的转录因子;（2）通过VNTR2 - 1鉴定调控TERT基因转录的关键末端 负责TERT抑制的调控元件;和（3）研究这些远端元件在 使用我们的具有人源化端粒的小鼠模型调节端粒体内稳态。简而言之，使用我们的 独特的工具，我们将解决一些基本的机制，端粒酶调控的关键， 人类端粒内稳态，以及最终端粒相关的人类疾病。

Abstract Our long-term goal is to decipher the molecular mechanisms of telomerase regulation and telomere homeostasis during development. Telomerase elongates telomeres to compensate for their loss during cell proliferation. Its regulation is critical for human aging and susceptibilities to cancer and many age-related degenerative diseases. The TERT gene, encoding the human telomerase reverse transcriptase, is regulated primarily at the level of transcription. It is highly expressed in pluripotent stem cells, but stringently repressed in most somatic cells. Recent progresses on telomerase regulation in cancer cells have greatly improved our understanding of TERT gene activation during cancer development. However, the mechanisms of its repression in most differentiated cells and expression in certain somatic cells remain to be elucidated. Regulation of transcription during development and differentiation often involves distal elements and chromatin reorganization. We previously reported that the endogenous TERT gene was embedded in a condensed chromatin domain and stringently repressed in a histone deacetylase-dependent manner in somatic cells. To identify distal regulatory sequences required for establishing the repressive chromatin of the TERT locus and to understand its regulation in vivo, our laboratory has developed two innovative technical platforms in the past decade. The first is recombinase-mediated BAC targeting or RMBT method, for targeted integration of single-copy BAC reporters into specified chromosomal sites. This technique, together with the new CRISPR-mediated gene editing, enables us to study distal regulatory elements of the TERT gene in their genomic contexts. Consequently, we have discovered that a polymorphic tandem DNA repeat in intron 2 (VNTR2-1) functions as an enhancer for TERT transcription. In addition, we have engineered a humanized mTert allele (hmTert) for studying human-specific telomerase regulation in mice. In the next funding period, we plan to use these tools and focus on the following three directions: (1) Identify transcription factors that regulate TERT gene via VNTR2-1; (2) Identify key distal regulatory elements responsible for TERT repression; and (3) Study the roles of these distal elements in regulating telomere homeostasis in vivo using our mouse model with humanized telomeres. In short, using our unique tools, we will address some of the fundamental mechanisms critical to telomerase regulation and telomere homeostasis in humans, and ultimately telomere-associated human diseases.