ACCELERATION OF THE G(1)/S PHASE-TRANSITION BY EXPRESSION OF CYCLIN-D1 AND CYCLIN-E WITH AN INDUCIBLE SYSTEM
ACCELERATION OF THE G(1)/S PHASE-TRANSITION BY EXPRESSION OF CYCLIN-D1 AND CYCLIN-E WITH AN INDUCIBLE SYSTEM
复制标题
DOI：
10.1128/mcb.14.3.1669
复制
发表时间：
1994-03-01
影响因子：
5.3
通讯作者：
REED, SI
中科院分区：
文献类型：
--
作者：
RESNITZKY, D;GOSSEN, M;REED, SI
通过使用基于大肠杆菌四环素阻遏物的合成 cDNA 表达系统，实现了人细胞周期蛋白 B1、D1 和 E 的条件过表达。在异步 Rat-1 成纤维细胞中诱导这些细胞周期蛋白后，观察到细胞周期蛋白 D1 和 E 的 G(1) 间隔长度缩短，这与 G(1)/S 相变的加速一致。此外，我们还观察到 S 期和 G(2) 的补偿性延长，因此组成型表达这些细胞周期蛋白的群体的平均细胞周期长度相对于未诱导的对应物而言没有变化。我们发现，尽管细胞周期蛋白 B 相关组蛋白 H1 激酶活性水平升高，但细胞周期蛋白 B1 的表达对细胞周期动力学没有影响。细胞周期蛋白 D1 和 E 的诱导还加速了从静止状态出现的同步培养物进入 S 期的速度。然而，在异步循环细胞中，细胞周期蛋白 E 比细胞周期蛋白 D1 发挥更大的作用，而细胞周期蛋白 D1 对静止刺激产生更大的作用，表明细胞周期蛋白 D1 在 G(0) 到 G(1) 转变中的特定作用。细胞周期蛋白的过度表达并不能阻止细胞在血清饥饿时进入静止状态，尽管表达细胞周期蛋白 D1 或细胞周期蛋白 E 的细胞在达到静止状态方面观察到了轻微的延迟。这些结果表明，细胞周期蛋白 D1 和 E 是 G(1) 至 S 相转变的限速激活剂，并且细胞周期蛋白 D1 可能在促进从静止状态的出现中发挥特殊作用。
Conditional overexpression of human cyclins B1, D1, and E was accomplished by using a synthetic cDNA expression system based on the Escherichia coli tetracycline repressor. After induction of these cyclins in asynchronous Rat-1 fibroblasts, a decrease in the length of the G(1) interval was observed for cyclins D1 and E, consistent with an acceleration of the G(1)/S phase transition. We observed, in addition, a compensatory lengthening of S phase and G(2) so that the mean cell cycle length in populations constitutively expressing these cyclins was unchanged relative to those of their uninduced counterparts. We found that expression of cyclin B1 had no effect on cell cycle dynamics, despite elevated levels of cyclin B-associated histone H1 kinase activity. Induction of cyclins D1 and E also accelerated entry into S phase for synchronized cultures emerging from quiescence. However, whereas cyclin E exerted a greater effect than cyclin D1 in asynchronous cycling cells, cyclin D1 conferred a greater effect upon stimulation from quiescence, suggesting a specific role for cyclin D1 in the G(0)-to-G(1) transition. Overexpression of cyclins did not prevent cells from entering into quiescence upon serum starvation, although a slight delay in attainment of quiescence was observed for cells expressing either cyclin D1 or cyclin E. These results suggest that cyclins D1 and E are rate-limiting activators of the G(1)-to-S phase transition and that cyclin D1 might play a specialized role in facilitating emergence from quiescence.