Stacey Dennis W
Department of Molecular Biology, The Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
Curr Opin Cell Biol. 2003 Apr;15(2):158-63. doi: 10.1016/s0955-0674(03)00008-5.
Much of our current understanding of the cell cycle involves analyses of its induction in quiescent cells. To better understand the control of cell cycle propagation and termination, studies have been performed in actively cycling cultures using time-lapse photography and quantitative image analysis. These studies reveal a highly ordered sequence of events required for promotion of continued proliferation. The decision to continue cell cycle progression takes place in G2 phase, when cellular Ras induces the elevation of cyclin D1 levels. These levels are maintained through G1 phase and are required for the initiation of S phase, at which time cyclin D1 levels are automatically reduced to low levels. The reduction of cyclin D1 to low levels during S phase is required for DNA synthesis, and forces the cell to induce high cyclin D1 levels once again when it enters G2 phase. In this way, cyclin D1 is proposed to serve as an active switch in the regulation of continued cell cycle progression.
我们目前对细胞周期的许多理解都涉及对静止细胞中细胞周期诱导的分析。为了更好地理解细胞周期传播和终止的控制，已经使用延时摄影和定量图像分析在活跃循环培养物中进行了研究。这些研究揭示了促进持续增殖所需的高度有序的事件序列。继续细胞周期进程的决定发生在G2期，此时细胞Ras诱导细胞周期蛋白D1水平升高。这些水平在G1期维持，并是启动S期所必需的，此时细胞周期蛋白D1水平会自动降至低水平。S期细胞周期蛋白D1降至低水平是DNA合成所必需的，并迫使细胞在进入G2期时再次诱导高细胞周期蛋白D1水平。通过这种方式，细胞周期蛋白D1被认为是调节细胞周期持续进程的一个活跃开关。
