p53 Configures the G2/M Arrest Response of Nucleostemin-Deficient Cells.
p53 Configures the G2/M Arrest Response of Nucleostemin-Deficient Cells.
复制标题
DOI：
10.1038/cddiscovery.2015.60
复制
发表时间：
2015
影响因子：
7
通讯作者：
Tsai RY
中科院分区：
文献类型：
--
作者：
Huang G;Meng L;Tsai RY
Nucleostemin (NS) 保护基因组免受复制诱导的 DNA 损伤，并且在维持 p53 野生型和突变细胞的持续增殖中具有不可或缺的作用。然而，NS 缺陷细胞的一些结果似乎是由它们的 p53 状态决定的，这引发了关于 p53 在执行 NS 功能中的作用的相互矛盾的说法。这种差异很容易归因于细胞类型变异的常见嫌疑。为了提供明确的解决方案，我们研究了两对同基因细胞（即转基因小鼠胚胎成纤维细胞 (MEF) 细胞和 HCT116 人结肠癌细胞）中 NS 和 p53 之间的相互作用。在 MEF 细胞中，p53 缺失进一步损害而不是挽救 NS 耗尽细胞的增殖潜力，而不改变其进入前期之前的 G2/M 停滞命运。 NS 耗尽的 MEF 细胞中 p53 缺失的有害影响与多倍体巨细胞 (PGC) 的急剧增加（高达 24%）相关，这表明有丝分裂异常。为了确定 p53 如何在分子水平上影响细胞对 NS 耗竭的反应，我们发现 p53 在 NS 缺陷的 MEF 细胞中开启 reprimo 和 MDM2 的表达。在缺乏 p53 的情况下，NS 缺陷的 MEF 细胞表现出磷酸化 cdc2 (Y15) 蛋白和细胞周期蛋白 B1 水平升高。在癌症 (HCT116) 细胞中，NS 丢失会导致 p53wt 和 p53ko 条件下的 G2/M 期停滞，并且 p53ko 中的磷酸化 cdc2 比 p53wt 细胞中磷酸化的 cdc2 增加更多，就像在 MEF 细胞中一样。与 MEF 细胞中的作用不同，NS 耗竭会减少 HCT116 细胞中的肿瘤生长，并以 p53 独立的方式增加 reprimo 和细胞周期蛋白 B1 的表达。我们的数据表明，NS 缺陷细胞的 p53 状态以正常细胞与癌细胞不同的方式协调它们对 G2/M 期停滞的反应。
Nucleostemin (NS) protects the genome from replication-induced DNA damage and has an indispensable role in maintaining the continuous proliferation of both p53-wild-type and mutant cells. Yet, some outcomes of NS-deficient cells appear to be shaped by their p53 status, which stimulates conflicting claims on the role of p53 in executing the NS function. This disparity was conveniently attributed to the usual suspect of cell-type variations. To provide a definitive resolution, we investigated the interplay between NS and p53 in two pairs of isogenic cells, that is, genetically modified mouse embryonic fibroblast (MEF) cells and HCT116 human colon cancer cells. In MEF cells, p53 deletion further compromises rather than rescues the proliferative potential of NS-depleted cells without changing their G2/M arrest fate before prophase entry. The detrimental effect of p53 loss in NS-depleted MEF cells correlates with a dramatic increase of polyploid giant cells (PGCs) (up to 24%), which indicates aberrant mitosis. To determine how p53 shapes the response of cells to NS depletion at the molecular level, we showed that p53 turns on the expression of reprimo and MDM2 in NS-deficient MEF cells. In absence of p53, NS-deficient MEF cells exhibit increased levels of phosphorylated cdc2 (Y15) protein and cyclin B1. In cancer (HCT116) cells, NS loss leads to G2/M arrest under both p53wt and p53ko conditions and increases phosphorylated cdc2 more in p53ko than in p53wt cells, as it does in MEF cells. Unlike its effect in MEF cells, NS depletion decreases tumor growth and increases the expression of reprimo and cyclin B1 in a p53-independent manner in HCT116 cells. Our data indicate that the p53 status of NS-deficient cells orchestrates how they respond to G2/M arrest in a normal versus cancer cell distinct fashion.