ATM is required for the cellular response to thymidine induced replication fork stress.
Genetically distinct checkpoints, activated as a consequence of either DNA replication arrest or ionizing radiation-induced DNA damage, integrate DNA repair responses into the cell cycle programme. The ataxia-telangiectasia mutated (ATM) protein kinase blocks cell cycle progression in response to DNA double strand breaks, whereas the related ATR is important in maintaining the integrity of the DNA replication apparatus. Here, we show that thymidine, which slows the progression of replication forks by depleting cellular pools of dCTP, induces a novel DNA damage response that, uniquely, depends on both ATM and ATR. Thymidine induces ATM-mediated phosphorylation of Chk2 and NBS1 and an ATM-independent phosphorylation of Chk1 and SMC1. AT cells exposed to thymidine showed decreased viability and failed to induce homologous recombination repair (HRR). Taken together, our results implicate ATM in the HRR-mediated rescue of replication forks impaired by thymidine treatment.
Institute for Cancer Studies, School of Medicine, University of Sheffield, UK.
Emma
E
Bolderson
Jennifer
J
Scorah
Thomas
T
Helleday
Carl
C
Smythe
Mark
M
Meuth
D064007:Ataxia Telangiectasia Mutated Proteins; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology*; D002461:Cell Line, Transformed; D004261:DNA Replication / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology*; D034741:RNA, Small Interfering; D011995:Recombination, Genetic / Q000502:physiology; D013936:Thymidine / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000502:physiology*
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D013936:Thymidine