Logan T J, Jordan K L, Hall D J
Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Biochem Cell Biol. 1996;74(1):21-8. doi: 10.1139/o96-003.
The E2F1 transcription factor was constitutively expressed in NIH3T3 fibroblasts to determine its effect on the cell cycle. These E2F1 cell lines were not tightly synchronized in G0 phase of the cell cycle following serum starvation, as are normal fibroblasts. Instead, the cells are spread throughout G0 and G1 phase with a portion of the population initiating DNA synthesis. Upon serum stimulation, the remaining cells in G0/G1 begin to enter S phase immediately but with a reduced rate. Constitutive expression of E2F1 appears to primarily affect the G0 phase, since transit of proliferating E2F1 cell lines through G1 phase is the same as control cells. Consistent with a shortened G0 phase, the E2F1 cell lines have a significantly reduced cellular volume. Additionally, the first S phase after serum stimulation, but not subsequent S phases, is nearly doubled in the E2F1 cell lines compared with control cells. Cell lines expressing a deletion mutant of E2F1 (termed E2F1d87), known to significantly affect cell shape, have cell cycle and volume characteristics similar to the E2F1 expressing cells. However, all S phase durations are considerably lengthened and the cells demonstrate delayed growth after plating.
将E2F1转录因子在NIH3T3成纤维细胞中组成型表达，以确定其对细胞周期的影响。与正常成纤维细胞不同，这些E2F1细胞系在血清饥饿后并未在细胞周期的G0期紧密同步。相反，细胞分布在整个G0和G1期，一部分细胞开始进行DNA合成。血清刺激后，G0/G1期剩余的细胞立即开始进入S期，但速率降低。E2F1的组成型表达似乎主要影响G0期，因为增殖的E2F1细胞系通过G1期的过程与对照细胞相同。与缩短的G0期一致，E2F1细胞系的细胞体积显著减小。此外，与对照细胞相比，E2F1细胞系在血清刺激后的第一个S期（而非随后的S期）几乎延长了一倍。表达已知会显著影响细胞形状的E2F1缺失突变体（称为E2F1d87）的细胞系，其细胞周期和体积特征与表达E2F1的细胞相似。然而，所有S期的持续时间都显著延长，并且细胞在接种后显示出生长延迟。
