Evidence that a free-running oscillator drives G1 events in the budding yeast cell cycle
Evidence that a free-running oscillator drives G1 events in the budding yeast cell cycle
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作者：
Haase, SB;Reed, SI
在酵母和体细胞中，机制确保细胞周期事件仅在先前事件完成时启动（1）。相比之下，许多生物体早期胚胎细胞中特定细胞周期过程的中断不会影响后续事件的时间（2），表明细胞周期事件是由自由运行的细胞周期振荡器触发的。在这里，我们提出了一个独立的细胞周期振荡器的芽殖酵母酿酒酵母的证据。我们观察到周期性激活的事件通常局限于G1期的细胞周期，在细胞缺乏有丝分裂细胞周期蛋白依赖性激酶的活动，是必不可少的细胞周期的进展，在胚胎细胞，G1期事件循环的时间表，在S期或有丝分裂的情况下，与野生型细胞的细胞周期时间相似。在G1期细胞周期蛋白（Cln）和有丝分裂细胞周期蛋白（Clb）相关激酶活性的情况下，在响应交配信息素的细胞中观察到类似周期性的振荡，表明振荡器可能独立于细胞周期蛋白依赖性激酶动力学发挥作用。我们还表明，Clb相关的激酶活性是必不可少的，以确保依赖性，防止启动新的G1期事件时，细胞周期进展延迟。
In yeast and somatic cells, mechanisms ensure cell-cycle events are initiated only when preceding events have been completed(1). In contrast, interruption of specific cell-cycle processes in early embryonic cells of many organisms does not affect the timing of subsequent events(2), indicating that cell-cycle events are triggered by a free-running cell-cycle oscillator. Here we present evidence for an independent cell-cycle oscillator in the budding yeast Saccharomyces cerevisiae. We observed periodic activation of events normally restricted to the G1 phase of the cell cycle, in cells lacking mitotic cyclin-dependent kinase activities that are essential far cell-cycle progression, As in embryonic cells, G1 events cycled on schedule, in the absence of S phase or mitosis, with a period similar to the cell-cycle time of wild-type cells. Oscillations of similar periodicity were observed in cells responding to mating pheromone in the absence of G1 cyclin (Cln)- and mitotic cyclin (Clb)-associated kinase activity, indicating that the oscillator may function independently of cyclin-dependent kinase dynamics. We also show that Clb-associated kinase activity is essential for ensuring dependencies by preventing the initiation of new G1 events when cell-cycle progression is delayed.