Characterization of the p53-dependent postmitotic checkpoint following spindle disruption
Characterization of the p53-dependent postmitotic checkpoint following spindle disruption
复制标题
DOI：
10.1128/mcb.18.2.1055
复制
发表时间：
1998-02-01
影响因子：
5.3
通讯作者：
Jacks, T
中科院分区：
文献类型：
--
作者：
Lanni, JS;Jacks, T
已知p53肿瘤抑制基因产物在DNA损伤后作为G₁期细胞周期检查点的一部分发挥作用。为了研究p53在有丝分裂纺锤体破坏后作为有丝分裂检查点的一种新提出的作用，我们使用了延时视频显微镜技术，结果表明用纺锤体药物诺考达唑处理的p53（+/+）和p53（-/-）小鼠成纤维细胞在有丝分裂期停滞的时间相同。因此，p53不参与有丝分裂的检查点功能。然而，p53在经诺考达唑处理、已退出有丝分裂停滞但未进行胞质分裂从而适应了的细胞中起着关键作用。我们已经确定，在经诺考达唑处理且已适应的细胞中，p53在一个特定的时间窗口内是必需的，以防止细胞重新进入细胞周期并启动另一轮DNA合成。尽管具有4N的DNA含量，但适应的细胞与G₁期细胞相似，它们的细胞周期蛋白E表达上调且Rb蛋白低磷酸化。在经诺考达唑处理且已适应的细胞中，p53依赖性停滞的机制需要细胞周期蛋白依赖性激酶抑制剂p21，因为p21（-/-）成纤维细胞在诺考达唑处理后不能停滞并变成多倍体。此外，在诺考达唑处理或照射后维持细胞周期停滞所需的p21程度相似。因此，纺锤体破坏后的p53依赖性检查点在功能上与DNA损伤后的p53依赖性检查点重叠。
The p53 tumor suppressor gene product is known to act as part of a cell cycle checkpoint in G(1) following DNA damage. In order to investigate a proposed novel role for p53 as a checkpoint at mitosis following disruption of the mitotic spindle, we have used time-lapse videomicroscopy to show that both p53(+/+) and p53(-/-) murine fibroblasts treated with the spindle drug nocodazole undergo transient arrest at mitosis for the same length of time, Thus, p53 does not participate in checkpoint function at mitosis. However, p53 does play a critical role in nocodazole-treated cells which have exited mitotic arrest without undergoing cytokinesis and have thereby adapted, We have determined that in nocodazole-treated, adapted cells, p53 is required during a specific time window to prevent cells from reentering the cell cycle and initiating another round of DNA synthesis, Despite having 4N DNA content, adapted cells are similar to G(1) cells in that they have upregulated cyclin E expression and hypophosphorylated Rb protein. The mechanism of the p53-dependent arrest in nocodazole-treated adapted cells requires the cyclin-dependent kinase inhibitor p21, as p21(-/-) fibroblasts fail to arrest in response to nocodazole treatment and become polyploid. Moreover, p21 is required to a similar extent to maintain cell cycle arrest after either nocodazole treatment or irradiation, Thus, the p53-dependent checkpoint following spindle disruption functionally overlaps with the p53-dependent checkpoint following DNA damage.