Telomeric function of mammalian telomerases at short telomeres
Telomeric function of mammalian telomerases at short telomeres
复制标题
DOI：
10.1242/jcs.063636
复制
发表时间：
2010-05-15
影响因子：
4
通讯作者：
Autexier, Chantal
中科院分区：
文献类型：
--
作者：
Fakhoury, Johans;Marie-Egyptienne, Delphine Tamara;Autexier, Chantal
端粒酶合成端粒序列，并且最低限度地由称为TERT的逆转录酶（RT）和称为TR的RNA组成。我们在体外和永生化的人端粒替代延长（ALT）细胞中重建了异源小鼠（m）和人（h）TERT-TR复合物和嵌合mTERT-hTERT-hTR复合物。我们的数据表明，物种特异性的活动，持续合成能力和端粒功能的决定因素不仅映射到TR，但也到TERT组件。hTERT-hTR的存在，而不是异源TERT-TR复合物或嵌合mTERT-hTERT-hTR复合物的存在，显着降低ALT细胞中没有端粒信号的染色体的百分比。此外，异源和嵌合复合物在端粒的募集方面存在缺陷。我们的研究结果表明，需要几个hTERT域和多个蛋白质的相互作用，以适当的招聘端粒酶在人类ALT细胞中的最短的端粒。异位表达hTERT或mTERT的晚期传代mTERT-/-小鼠胚胎干（ES）细胞比通常在晚期传代mTERT-/-ES细胞中观察到的具有更少的染色体末端而没有端粒信号和端对端融合。hTERT在小鼠端粒中发挥作用的能力和mTERT在人端粒中不能发挥作用表明，调节hTERT在小鼠端粒中的募集和活性的机制可能不如调节mTERT在人端粒中的机制严格。
Telomerase synthesizes telomeric sequences and is minimally composed of a reverse transcriptase (RT) known as TERT and an RNA known as TR. We reconstituted heterologous mouse (m) and human (h) TERT-TR complexes and chimeric mTERT-hTERT-hTR complexes in vitro and in immortalized human alternative lengthening of telomere (ALT) cells. Our data suggest that species-specific determinants of activity, processivity and telomere function map not only to the TR but also to the TERT component. The presence of hTERT-hTR, but not heterologous TERT-TR complexes or chimeric mTERT-hTERT-hTR complexes, significantly reduced the percentage of chromosomes without telomeric signals in ALT cells. Moreover, heterologous and chimeric complexes were defective in recruitment to telomeres. Our results suggest a requirement for several hTERT domains and interaction with multiple proteins for proper recruitment of telomerase to the shortest telomeres in human ALT cells. Late-passage mTERT-/-mouse embryonic stem (ES) cells ectopically expressing hTERT or mTERT harboured fewer chromosome ends without telomeric signals and end-to-end fusions than typically observed in late-passage mTERT-/-ES cells. The ability of hTERT to function at mouse telomeres and the inability of mTERT to function at human telomeres suggest that mechanisms regulating the recruitment and activity of hTERT at mouse telomeres might be less stringent than the mechanisms regulating mTERT at human telomeres.