Overexpression of telomerase confers growth advantage, stress resistance, and enhanced differentiation of ESCs toward the hematopoietic lineage
Overexpression of telomerase confers growth advantage, stress resistance, and enhanced differentiation of ESCs toward the hematopoietic lineage
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DOI：
10.1634/stemcells.2004-0269
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发表时间：
2005-04-01
期刊：
影响因子：
5.2
通讯作者：
Lako, M
中科院分区：
文献类型：
--
作者：
Armstrong, L;Saretzki, G;Lako, M
胚胎干细胞（ESCs）能够扩展自我更新和维持多能性，即使在许多种群加倍之后。这是由ESCs中高水平的端粒酶活性和增强的抗氧化保护所支持的，这两者在分化过程中都被下调。为了研究端粒酶在ESC自我更新和分化中的作用，我们在ESC中过表达小鼠端粒酶的逆转录酶亚基（Tert）。端粒酶活性的增加增强了过表达tert的内皮细胞的自我更新能力，提高了其抗凋亡能力，促进了其增殖。野生型ESCs的分化后代表达Tert较少，端粒悬垂缩短。相比之下，tert过表达的ESCs后代保持高端粒酶活性，以及富含g的悬垂长度。此外，与野生型细胞相比，这些细胞积累的过氧化物浓度更低，这意味着它们对氧化应激的抵抗力更强。最后，由于Tert的持续表达，向造血谱系的分化更有效。微阵列分析显示，Tert的过表达改变了延长自我更新和寿命所需的多种基因的表达。我们的研究结果表明，端粒酶通过保护端粒帽和影响应激反应和防御基因的表达模式，在ESCs及其分化后代中发挥“生存酶”的作用。这导致了ESCs增殖的改善和更有效的分化，这些结果可能对干细胞替代疗法产生深远的影响。
Embryonic stem cells (ESCs) are capable of extended self-renewal and maintenance of pluripotency even after many population doublings. This is supported by high levels of telomerase activity and enhanced antioxidant protection in ESCs, both of which are downregulated during differentiation. To examine the role of telomerase for ESC self-renewal and differentiation, we overexpressed the reverse transcriptase subunit (Tert) of murine telomerase in ESCs. Increased telomerase activity enhances the self-renewal ability of the Tert-overexpressing ESCs, improves their resistance to apoptosis, and increases their proliferation. The differentiated progeny of wild-type ESCs express little Tert and show shortening of telomeric overhangs. In contrast, the progeny of Tert-overexpressing ESCs maintain high telomerase activity, as well as the length of G-rich over-hangs. In addition, these cells accumulate lower concentrations of peroxides than wild-type cells, implying greater resistance to oxidative stress. Finally, differentiation toward hematopoietic lineages is more efficient as a result of the continued expression of Tert. Microarray analysis revealed that overexpression of Tert altered expression of a variety of genes required for extended self-renewal and lifespan. Our results suggest that telomerase functions as a "survival enzyme" in ESCs and its differentiated progeny by protecting the telomere cap and by influencing the expression patterns of stress response and defense genes. This results in improved proliferation of ESCs and more efficient differentiation, and these results might have profound consequences for stem cell-replacement therapies.