Cdc7 kinase mediates Claspin phosphorylation in DNA replication checkpoint.
Cdc7 kinase is evolutionarily conserved and is involved in initiation and progression of DNA replication. However, roles of Cdc7 in checkpoint responses remain largely unknown. In this study, we show that deletion of the Cdc7 genes in mouse embryonic stem (ES) cells abrogates hydroxyurea (HU)- or UV-induced activation of Chk1. HU-induced Chk1 activation is also impaired in human cancer cell lines in which Cdc7 is depleted by siRNA, and Cdc7-depleted cells are more sensitive to HU treatment. In contrast, ATR and Rad17 are relocated to chromatin in these cells following HU treatment, indicating that stalled DNA replication forks are detected normally. Cdc7-depleted cells exhibit defects in chromatin association and phosphorylation of Claspin, suggesting that Cdc7 exerts its effect at least partially through Claspin. Consistent with this prediction, Cdc7 interacts with and phosphorylates Claspin. We propose that Cdc7 is required for activation of the ATR-Chk1 checkpoint pathway through regulation of Claspin.
Kim
J M
JM
Genome Dynamics Project, The Tokyo Metropolitan Institute of Medical Science, Bunkyo-ku, Tokyo, Japan.
Kakusho
N
N
Yamada
M
M
Kanoh
Y
Y
Takemoto
N
N
Masai
H
H
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D064007:Ataxia Telangiectasia Mutated Proteins; D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured / Q000187:drug effects / Q000528:radiation effects; D000071877:Checkpoint Kinase 1; D002843:Chromatin / Q000502:physiology; D004261:DNA Replication; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D014162:Transfection; D014466:Ultraviolet Rays
D048868:Adaptor Proteins, Signal Transducing; D000970:Antineoplastic Agents; C488158:CLSPN protein, human; D018797:Cell Cycle Proteins; D002843:Chromatin; C113575:Rad17 protein, human; D011494:Protein Kinases; C068619:CDC7 protein, human; C489403:Cdc7 protein, mouse; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C000605869:Chek1 protein, mouse; D017346:Protein Serine-Threonine Kinases; D006918:Hydroxyurea