ATM and Artemis promote homologous recombination of radiation-induced DNA double-strand breaks in G2.
Homologous recombination (HR) and non-homologous end joining (NHEJ) represent distinct pathways for repairing DNA double-strand breaks (DSBs). Previous work implicated Artemis and ATM in an NHEJ-dependent process, which repairs a defined subset of radiation-induced DSBs in G1-phase. Here, we show that in G2, as in G1, NHEJ represents the major DSB-repair pathway whereas HR is only essential for repair of approximately 15% of X- or gamma-ray-induced DSBs. In addition to requiring the known HR proteins, Brca2, Rad51 and Rad54, repair of radiation-induced DSBs by HR in G2 also involves Artemis and ATM suggesting that they promote NHEJ during G1 but HR during G2. The dependency for ATM for repair is relieved by depleting KAP-1, providing evidence that HR in G2 repairs heterochromatin-associated DSBs. Although not core HR proteins, ATM and Artemis are required for efficient formation of single-stranded DNA and Rad51 foci at radiation-induced DSBs in G2 with Artemis function requiring its endonuclease activity. We suggest that Artemis endonuclease removes lesions or secondary structures, which inhibit end resection and preclude the completion of HR or NHEJ.
Beucher
Andrea
A
Darmstadt University of Technology, Radiation Biology and DNA Repair, Darmstadt, Germany.
Birraux
Julie
J
Tchouandong
Leopoldine
L
Barton
Olivia
O
Shibata
Atsushi
A
Conrad
Sandro
S
Goodarzi
Aaron A
AA
Krempler
Andrea
A
Jeggo
Penny A
PA
Löbrich
Markus
M
D051017:Apoptosis Regulatory Proteins; D064007:Ataxia Telangiectasia Mutated Proteins; D024682:BRCA2 Protein / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects*; D004265:DNA Helicases; D004260:DNA Repair / Q000187:drug effects; D045643:DNA Repair Enzymes / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004720:Endonucleases; D005347:Fibroblasts / Q000528:radiation effects; D016193:G1 Phase / Q000528:radiation effects; D016195:G2 Phase / Q000528:radiation effects*; D017353:Gene Deletion; D006367:HeLa Cells; D006570:Heterochromatin / Q000378:metabolism; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D051135:Rad51 Recombinase / Q000378:metabolism; D051716:Replication Protein A / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
D051017:Apoptosis Regulatory Proteins; C118024:BLID protein, human; D024682:BRCA2 Protein; C551750:BRCA2 protein, human; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D006570:Heterochromatin; C508551:NHEJ1 protein, human; D009687:Nuclear Proteins; D051716:Replication Protein A; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D051135:Rad51 Recombinase; C426344:DCLRE1C protein, human; D004720:Endonucleases; D004265:DNA Helicases; C103532:RAD54L protein, human; D045643:DNA Repair Enzymes