From the Department of Cell Differentiation, The Sakaguchi Laboratory, School of Medicine, Keio University, Tokyo, 160-8582.
From the Department of Cell Differentiation, The Sakaguchi Laboratory, School of Medicine, Keio University, Tokyo, 160-8582, Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, the Department of Stem Cell Biology and Medicine, Graduate School of Medical Science, Kyushu University, Fukuoka, 812-8582,
J Biol Chem. 2014 May 30;289(22):15776-87. doi: 10.1074/jbc.M113.536037. Epub 2014 Apr 14.
Reactivation of the endogenous telomerase reverse transcriptase (TERT) catalytic subunit and telomere elongation occur during the reprogramming of somatic cells to induced pluripotent stem (iPS) cells. However, the role of TERT in the reprogramming process is unclear. To clarify its function, the reprogramming process was examined in TERT-KO somatic cells. To exclude the effect of telomere elongation, tail-tip fibroblasts (TTFs) from first generation TERT-KO mice were used. Although iPS cells were successfully generated from TERT-KO TTFs, the efficiency of reprogramming these cells was markedly lower than that of WT TTFs. The gene expression profiles of iPS cells induced from TERT-KO TTFs were similar to those of WT iPS cells and ES cells, and TERT-KO iPS cells formed teratomas that differentiated into all three germ layers. These data indicate that TERT plays an extratelomeric role in the reprogramming process, but its function is dispensable. However, TERT-KO iPS cells showed transient defects in growth and teratoma formation during continuous growth. In addition, TERT-KO iPS cells developed chromosome fusions that accumulated with increasing passage numbers, consistent with the fact that TERT is essential for the maintenance of genome structure and stability in iPS cells. In a rescue experiment, an enzymatically inactive mutant of TERT (D702A) had a positive effect on somatic cell reprogramming of TERT-KO TTFs, which confirmed the extratelomeric role of TERT in this process.
端粒酶逆转录酶（TERT）催化亚基的重新激活和端粒延长发生在体细胞重编程为诱导多能干细胞（iPS）细胞的过程中。然而，TERT 在重编程过程中的作用尚不清楚。为了阐明其功能，在 TERT-KO 体细胞的重编程过程中进行了检查。为了排除端粒延长的影响，使用了第一代 TERT-KO 小鼠的尾巴尖端成纤维细胞（TTFs）。尽管成功地从 TERT-KO TTFs 中生成了 iPS 细胞，但这些细胞的重编程效率明显低于 WT TTFs。从 TERT-KO TTFs 诱导的 iPS 细胞的基因表达谱与 WT iPS 细胞和 ES 细胞相似，TERT-KO iPS 细胞形成了能够分化为三个胚层的畸胎瘤。这些数据表明，TERT 在重编程过程中发挥着端粒外的作用，但它的功能是可有可无的。然而，在连续生长过程中，TERT-KO iPS 细胞的生长和畸胎瘤形成出现了短暂的缺陷。此外，TERT-KO iPS 细胞发生了染色体融合，随着传代次数的增加而积累，这与 TERT 对于维持 iPS 细胞基因组结构和稳定性是必不可少的事实一致。在挽救实验中，TERT 的一种酶失活突变体（D702A）对 TERT-KO TTFs 的体细胞重编程具有积极影响，这证实了 TERT 在该过程中具有端粒外的作用。
