Regulation and effects of modulation of telomerase reverse transcriptase expression in primordial germ cells during development
Regulation and effects of modulation of telomerase reverse transcriptase expression in primordial germ cells during development
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DOI：
10.1095/biolreprod.106.052167
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发表时间：
2006-11-01
影响因子：
3.6
通讯作者：
Allsopp, Richard
中科院分区：
文献类型：
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作者：
Coussens, Matthew;Yamazaki, Yukiko;Allsopp, Richard
端粒长度在生殖细胞系中的世代维持对于真核生物的永久存在是必不可少的。这项任务是由一种称为端粒酶的专门逆转录酶完成的。虽然端粒酶的这一关键功能已经得到了很好的确立，但对生殖细胞系中端粒酶的调控机制仍然知之甚少。现在，我们显示，使用Pousf 1-GFP转基因小鼠模型，端粒酶抑制在静止的男性原始生殖细胞（PGCs）是伴随着小鼠端粒酶逆转录酶（TERT）的表达减少。为了进一步评估TERT在静止PGCs中的作用，我们开发了鸡Actb基因启动子/巨细胞病毒增强子（CAG）-Tert转基因小鼠品系，其组成型表达鼠TERT。在CAG-Tert转基因胚胎的静止PGCs中检测到端粒酶活性，表明TERT表达的重新激活足以恢复这些细胞中的端粒酶活性，并且暗示TERT表达是PGCs中端粒酶调节的重要机制。PGC频率和细胞周期状态的荧光激活细胞分选（FACS）分析显示，无论是在CAG-Tert转基因小鼠或Tert敲除小鼠的过度表达或缺乏的TERT没有影响。这些结果表明，TERT本身不影响PGCs的增殖或发育，与最近的研究表明，TERT在某些干细胞中具有端粒独立的作用。可能的是，TERT对细胞行为的直接影响可能取决于细胞类型。
Telomere length maintenance in the germ line from generation to generation is essential for the perpetuation of eukaryotic organisms. This task is performed by a specialized reverse transcriptase called telomerase. While this critical function of telomerase has been well established, the mechanisms that regulate telomerase in the germ line are still poorly understood. We now show, using a Pousf1-GFP transgenic mouse model, that telomerase suppression in quiescent male primordial germ cells (PGCs) is accompanied by a decrease in expression of murine telomerase reverse transcriptase (TERT). To further assess the role of TERT in quiescent PGCs, we developed a chicken Actb gene promoter/cytomegalovirus enhancer (CAG)-Tert transgenic mouse strain that constitutively expresses murine TERT. Telomerase activity was detected in quiescent PGCs from CAG-Tert transgenic embryos, demonstrating that re-activation of TERT expression is sufficient to restore telomerase activity in these cells and implying that TERT expression is an important mechanism of telomerase regulation in PGCs. Fluorescence-activated cell-sorting (FACS) analysis of PGC frequency and cell cycle status revealed no effect of either overexpression or deficiency of TERT in CAG-Tert transgenic mice or Tert knock-out mice respectively. These results demonstrate that TERT per se does not affect proliferation or development of PGCs, in contrast with recent studies that suggest that TERT has a telomere-independent effect in certain stem cells. It is possible that the direct effect of TERT on cell behavior may be dependent on cell type.