Inactivation of Cdc7 kinase in mouse ES cells results in S-phase arrest and p53-dependent cell death
Inactivation of Cdc7 kinase in mouse ES cells results in S-phase arrest and p53-dependent cell death
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DOI：
10.1093/emboj/21.9.2168
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发表时间：
2002-05-01
期刊：
影响因子：
11.4
通讯作者：
Masai, H
中科院分区：
文献类型：
--
作者：
Kim, JM;Nakao, K;Masai, H
cdc7相关激酶在酵母DNA复制的起始过程中起着至关重要的作用。我们发现缺乏小鼠同源Cdc7 （muCdc7）基因的小鼠在E3.5和E6.5之间死亡。我们在表达muCdc7 cDNA的loxp -侧翼转基因存在下，建立了缺乏muCdc7基因的突变胚胎干（ES）细胞系。在用Cre重组酶去除转基因后，突变的ES细胞停止DNA合成，抑制s期DNA含量的生长，并产生核Rad51病灶，随后细胞死亡，同时p53蛋白水平升高。抑制p53可部分挽救muCdc7(-/-) ES细胞免于死亡。muCdc7(-/-)p53（-/-）胚胎存活至E8.5，其囊胚在体外产生显著大小的内细胞团，而muCdc7(-/-)p53（+/-）胚胎则完全变性。这些结果表明，与在酵母中观察到的G(1)/S边界的细胞周期阻滞不同，胚胎干细胞中Cdc7的缺失会导致S期DNA合成的快速停止，触发检查点反应，导致重组修复和p53依赖性细胞死亡。
Cdc7-related kinases play essential roles in the initiation of yeast DNA replication. We show that mice lacking murine homologs of Cdc7 (muCdc7) genes die between E3.5 and E6.5. We have established a mutant embryonic stem (ES) cell line lacking the muCdc7 genes in the presence of a loxP-flanked transgene expressing muCdc7 cDNA. Upon removal of the transgene by Cre recombinase, mutant ES cells cease DNA synthesis, arresting growth with S-phase DNA content, and generate nuclear Rad51 foci, followed by cell death with concomitant increase in p53 protein levels. Inhibition of p53 leads to partial rescue of muCdc7(-/-) ES cells from cell death. muCdc7(-/-)p53(-/-) embryos survive up to E8.5, and their blastocysts generate inner cell mass of a significant size in vitro, whereas those of the muCdc7(-/-)p53(+/-) embryos undergoes complete degeneration. These results demonstrate that, in contrast to cell cycle arrest at the G(1)/S boundary observed in yeasts, loss of Cdc7 in ES cells results in rapid cessation of DNA synthesis within S phase, triggering checkpoint responses leading to recombinational repair and p53-dependent cell death.