Development of mouse strains with human-like telomerase regulation

摘要 端粒作为一个衰老的时钟，因为大多数人体细胞缺乏 端粒酶表达和它们的端粒在连续的细胞分裂中逐渐缩短。 因此，端粒缩短是人类衰老的关键因素，而端粒酶激活是人类衰老的关键因素。 对许多人类癌症的发展至关重要。另一方面，来自一些 其他生物体，包括小鼠，不表现出端粒介导的复制性衰老。小鼠 在体细胞组织中具有长的异质性端粒和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基本问题的瓶颈。 人类衰老和癌症生物学中的问题。长期目标是 这个项目是用基因工程改造小鼠品系，使其具有类似人类的端粒稳态， 为了验证短端粒和受抑制的端粒酶赋予复制性衰老的假设， 小鼠我们最近的研究已经确定了几个远端调控元件，这些元件对 hTERT基因的阻遏。在本提案中，我们将检验以下假设： 将这些元件插入其相应的小鼠基因组位点导致类人TERT基因 小鼠的调节。我们将首先用人源化的 mTERT基因座（hmTERT），然后使用这些ESC产生具有人样突变的小鼠品系。 端粒酶调控hmTERT基因座的调节将在体外实验和体外培养中确定。 ESC分化和小鼠发育期间。我们预计这些老鼠将作为 一个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.