Inactivation of Cdc7 kinase in mouse ES cells results in S-phase arrest and p53-dependent cell death.
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.
Kim
Jung Min
JM
Department of Molecular and Developmental Biology, The Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo 108-8639, CREST, Tokyo 108-8639, Japan.
Nakao
Kazuki
K
Nakamura
Kenji
K
Saito
Izumu
I
Katsuki
Motoya
M
Arai
Ken-ichi
K
Masai
Hisao
H
D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology*; D016923:Cell Death / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line / Q000166:cytology / Q000502:physiology; D017353:Gene Deletion; D051379:Mice; D018345:Mice, Knockout; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology*; D016196:S Phase / Q000502:physiology*; D013234:Stem Cells / Q000166:cytology / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*
D018797:Cell Cycle Proteins; D016159:Tumor Suppressor Protein p53; C489403:Cdc7 protein, mouse; D017346:Protein Serine-Threonine Kinases