Radiation-induced double-strand breaks require ATM but not Artemis for homologous recombination during S-phase.

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Autor/in:
Erscheinungsjahr:
2012
Medientyp:
Text
Schlagworte:
  • Humans
  • Cell Line
  • Protein-Serine-Threonine Kinases/*physiology
  • Radiation Tolerance
  • Cell Cycle/genetics/radiation effects
  • Cell Cycle Proteins/*physiology
  • *DNA Breaks, Double-Stranded
  • DNA-Binding Proteins/*physiology
  • Nuclear Proteins/*physiology
  • Rad51 Recombinase/analysis
  • *Recombinational DNA Repair
  • S Phase/*genetics/radiation effects
  • Tumor Suppressor Proteins/*physiology
  • Humans
  • Cell Line
  • Protein-Serine-Threonine Kinases/*physiology
  • Radiation Tolerance
  • Cell Cycle/genetics/radiation effects
  • Cell Cycle Proteins/*physiology
  • *DNA Breaks, Double-Stranded
  • DNA-Binding Proteins/*physiology
  • Nuclear Proteins/*physiology
  • Rad51 Recombinase/analysis
  • *Recombinational DNA Repair
  • S Phase/*genetics/radiation effects
  • Tumor Suppressor Proteins/*physiology
Beschreibung:
  • Double-strand breaks (DSBs) are repaired by two distinct pathways, non-homologous end joining (NHEJ) and homologous recombination (HR). The endonuclease Artemis and the PIK kinase Ataxia-Telangiectasia Mutated (ATM), mutated in prominent human radiosensitivity syndromes, are essential for repairing a subset of DSBs via NHEJ in G1 and HR in G2. Both proteins have been implicated in DNA end resection, a mandatory step preceding homology search and strand pairing in HR. Here, we show that during S-phase Artemis but not ATM is dispensable for HR of radiation-induced DSBs. In replicating AT cells, numerous Rad51 foci form gradually, indicating a Rad51 recruitment process that is independent of ATM-mediated end resection. Those DSBs decorated with Rad51 persisted through S- and G2-phase indicating incomplete HR resulting in unrepaired DSBs and a pronounced G2 arrest. We demonstrate that in AT cells loading of Rad51 depends on functional ATR/Chk1. The ATR-dependent checkpoint response is most likely activated when the replication fork encounters radiation-induced single-strand breaks leading to generation of long stretches of single-stranded DNA. Together, these results provide new insight into the role of ATM for initiation and completion of HR during S- and G2-phase. The DSB repair defect during S-phase significantly contributes to the radiosensitivity of AT cells.
  • Double-strand breaks (DSBs) are repaired by two distinct pathways, non-homologous end joining (NHEJ) and homologous recombination (HR). The endonuclease Artemis and the PIK kinase Ataxia-Telangiectasia Mutated (ATM), mutated in prominent human radiosensitivity syndromes, are essential for repairing a subset of DSBs via NHEJ in G1 and HR in G2. Both proteins have been implicated in DNA end resection, a mandatory step preceding homology search and strand pairing in HR. Here, we show that during S-phase Artemis but not ATM is dispensable for HR of radiation-induced DSBs. In replicating AT cells, numerous Rad51 foci form gradually, indicating a Rad51 recruitment process that is independent of ATM-mediated end resection. Those DSBs decorated with Rad51 persisted through S- and G2-phase indicating incomplete HR resulting in unrepaired DSBs and a pronounced G2 arrest. We demonstrate that in AT cells loading of Rad51 depends on functional ATR/Chk1. The ATR-dependent checkpoint response is most likely activated when the replication fork encounters radiation-induced single-strand breaks leading to generation of long stretches of single-stranded DNA. Together, these results provide new insight into the role of ATM for initiation and completion of HR during S- and G2-phase. The DSB repair defect during S-phase significantly contributes to the radiosensitivity of AT cells.
Lizenz:
  • info:eu-repo/semantics/openAccess
Quellsystem:
Forschungsinformationssystem des UKE

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oai:pure.atira.dk:publications/31f374bd-ba56-4a7c-85f7-457107410059