Regulation of human telomerase

摘要 我们的长期目标是破译端粒酶调节和端粒的分子机制 发育过程中的动态平衡。端粒酶延长端粒以补偿它们在细胞中的丢失 扩散。它的调节对人类的衰老和癌症的易感性以及许多与年龄相关的疾病至关重要 退行性疾病。编码人类端粒酶逆转录酶的TERT基因受到调控 主要是在转录水平上。它在多能干细胞中高度表达，但在 大多数体细胞。最近关于癌细胞端粒酶调控的进展极大地改善了我们的 了解TERT基因在癌症发生发展过程中的激活。然而，它的压制机制 在大多数分化的细胞中，以及在某些体细胞中的表达仍有待阐明。规管 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基因被嵌入到一个浓缩的染色质结构域中，并且 在体细胞中以组蛋白脱乙酰酶依赖的方式被严格抑制。识别远端调控 建立TERT基因座抑制性染色质并了解其调控所需的序列 在体内，我们的实验室在过去的十年里开发了两个创新的技术平台。第一个是 重组酶介导的BAC靶向或RMBT方法，用于靶向整合单拷贝BAC记者 进入特定的染色体位置。这项技术与新的CRISPR介导的基因编辑一起，使 美国研究基因组环境中TERT基因的远端调控元件。因此，我们有 发现内含子2的多态串联DNA重复序列(VNTR2-1)是TERT的增强子 抄写。此外，我们还设计了一种人源化的mTert等位基因(Hmtert)，用于研究人类特有的基因。 小鼠端粒酶的调节。在下一个资金阶段，我们计划使用这些工具，并重点关注以下几个方面 三个方向：(1)识别通过VNTR2-1调节TERT基因的转录因子；(2)识别关键的末端 负责端粒酶逆转录酶抑制的调控元件；以及(3)研究这些末端元件在 使用人源化端粒的小鼠模型在体内调节端粒的动态平衡。简而言之，使用我们的 独特的工具，我们将解决一些对端粒酶调节和 人类端粒的动态平衡，以及最终与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.