The small subunit processome is required for cell cycle progression at G1
The small subunit processome is required for cell cycle progression at G1
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DOI：
10.1091/mbc.e04-06-0515
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发表时间：
2004-11-01
影响因子：
3.3
通讯作者：
Baserga, SJ
中科院分区：
文献类型：
--
作者：
Bernstein, KA;Baserga, SJ
没有核糖体的生物合成，mRNA翻译成蛋白质的过程停止，细胞生长停止。我们问核糖体生物合成是否是细胞周期调节的酵母酿酒酵母和裂殖酵母粟酒裂殖酵母，我们确定，它不是以相同的方式在后生动物细胞的调节。因此，我们将注意力转向通过核糖体生物合成传递细胞大小信息的细胞传感器。我们的研究结果表明，小亚基（SSU）的过程体，一个复杂的40个蛋白质和U3小核仁核糖体生物合成所必需的RNA组成，是不受有丝分裂调节。此外，Nan 1/Utp 17，SSU加工体蛋白，不提供核糖体生物合成和细胞生长之间的联系。然而，当单个SSU加工体蛋白被耗尽时，细胞停滞在细胞周期的G1期。G1后表达的蛋白质缺乏染色进一步支持了这种停滞。类似地，耗尽SSU加工体蛋白的同步化细胞不进入G2。这表明，当核糖体不再产生时，细胞停滞在G1期。因此，酵母细胞必须生长到临界大小，这取决于在细胞周期的G1期期间具有足够数量的核糖体，然后才能发生细胞分裂。
Without ribosome biogenesis, translation of mRNA into protein ceases and cellular growth stops. We asked whether ribosome biogenesis is cell cycle regulated in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe, and we determined that it is not regulated in the same manner as in metazoan cells. We therefore turned our attention to cellular sensors that relay cell size information via ribosome biogenesis. Our results indicate that the small subunit (SSU) processome, a complex consisting of 40 proteins and the U3 small nucleolar RNA necessary for ribosome biogenesis, is not mitotically regulated. Furthermore, Nan1/Utp17, an SSU processome protein, does not provide a link between ribosome biogenesis and cell growth. However, when individual SSU processome proteins are depleted, cells arrest in the G1 phase of the cell cycle. This arrest was further supported by the lack of staining for proteins expressed in post-G1. Similarly, synchronized cells depleted of SSU processome proteins did not enter G2. This suggests that when ribosomes are no longer made, the cells stall in the G1. Therefore, yeast cells must grow to a critical size, which is dependent upon having a sufficient number of ribosomes during the G1 phase of the cell cycle, before cell division can occur.