Development of mouse strains with human-like telomerase regulation

摘要 端粒起着衰老时钟的作用，因为大多数人类体细胞缺乏 随着细胞的连续分裂，端粒酶的表达及其端粒逐渐缩短。 因此，端粒缩短是人类衰老的关键因素，端粒酶激活是 对许多人类癌症的发展是必不可少的。另一方面，来自一些细胞的 其他生物，包括小鼠，没有表现出端粒介导的复制性衰老。老鼠 具有长的异质端粒和在体细胞组织中普遍存在的端粒酶活性。 这种物种间的差异已经成为解决许多根本问题的瓶颈 利用小鼠模型研究人类衰老和癌症生物学中的问题。因此，长期目标是 该项目是通过基因工程使小鼠品系具有类似人类的端粒动态平衡和 为了验证端粒短小和端粒酶被抑制导致复制性衰老的假说 老鼠。我们最近的研究已经确定了几个关键的末端调控元件 抑制hTERT基因的表达。在这项提议中，我们将检验以下假设： 这些元件进入相应的小鼠基因组位置导致了类似人类的TERT基因 对小鼠的调节。我们将首先设计一种人源化的小鼠胚胎干细胞 MTERT基因座(HmTERT)，然后使用这些ESCs产生与人类相似的小鼠品系 端粒酶调节。HmTERT基因座的调控将在体外确定 胚胎干细胞分化和小鼠发育过程中。我们预计这些老鼠将作为 一种研究人类衰老和癌症的改进模型。

Abstract Telomeres function as an aging clock because most human somatic cells lack telomerase expression and their telomeres progressively shorten upon successive cell divisions. Accordingly, telomere shortening is a critical factor of human aging and telomerase activation is essential for the development of many human cancers. On the other hand, cells from some other organisms, including mice, do not exhibit telomere-mediated replicative aging. Mice possess long heterogeneous telomeres and ubiquitous telomerase activities in somatic tissues. This inter-species difference has become a bottleneck for addressing many fundamental questions in human aging and cancer biology using mouse models. Thus, the long-term goal of this project is to genetically engineer mouse strains with human-like telomere homeostasis and to test the hypothesis that short telomeres and repressed telomerase confer replicative aging in mice. Our recent studies have identified several distal regulatory elements critical for the repression of hTERT gene. In this proposal, we will test the hypothesis that incorporation of these elements into their corresponding mouse genomic sites leads to human-like TERT gene regulation in mice. We will first engineer mouse embryonic stem cells (ESCs) with a humanized mTERT locus (hmTERT) and then use these ESCs to generate mouse strains with human-like telomerase regulation. The regulation of hmTERT locus will be determined both during in vitro ESC differentiation and during mouse development. We anticipate that these mice will serve as an improved model for studying human aging and cancer.