Holt S E, Aisner D L, Shay J W, Wright W E
Department of Cell Biology and Neuroscience, The University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75235-9039, USA.
Proc Natl Acad Sci U S A. 1997 Sep 30;94(20):10687-92. doi: 10.1073/pnas.94.20.10687.
Conflicting reports have appeared concerning the cell cycle regulation of telomerase activity and its possible repression during quiescence and cell differentiation. We have reexamined these issues in an attempt to uncover the basis for the discrepancies. Variations in extracted telomerase activity during the cell cycle are not observed in cells sorted on the basis of DNA content. Variations are observed in cells synchronized using some biochemical cell cycle inhibitors, but only with those agents where cellular toxicity is evident. A progressive decline in telomerase activity is observed in cells whose growth rate is reduced from seven to eight population doublings per week to one to two doublings per week. Telomerase is largely absent in cells that truly exit the cell cycle and do not divide over the 7-day period. Although it is not necessary for all cell types to regulate telomerase in the same way, we conclude that in the immortal cultured cell lines examined, extracted telomerase activity does not change significantly during progression through the stages of the cell cycle. Telomerase activity generally correlates with growth rate and is repressed in cells that exit the cell cycle and become quiescent.
关于端粒酶活性的细胞周期调控及其在静止期和细胞分化过程中可能受到的抑制，已经出现了相互矛盾的报道。我们重新审视了这些问题，试图找出差异的根源。在根据DNA含量分选的细胞中，未观察到细胞周期中端粒酶活性的变化。在使用某些生化细胞周期抑制剂同步化的细胞中观察到了变化，但仅在那些具有明显细胞毒性的试剂处理的细胞中出现。在生长速率从每周七到八次群体倍增降低到每周一到两次倍增的细胞中，观察到端粒酶活性逐渐下降。在真正退出细胞周期且在7天内不分裂的细胞中，端粒酶基本不存在。虽然并非所有细胞类型都必须以相同方式调节端粒酶，但我们得出结论，在所研究的永生培养细胞系中，在细胞周期各阶段的进程中，提取的端粒酶活性没有显著变化。端粒酶活性通常与生长速率相关，并在退出细胞周期并进入静止期的细胞中受到抑制。
