Mre11-Rad50-Nbs1-dependent processing of DNA breaks generates oligonucleotides that stimulate ATM activity.
DNA double-strand breaks (DSBs) can be processed by the Mre11-Rad50-Nbs1 (MRN) complex, which is essential to promote ataxia telangiectasia-mutated (ATM) activation. However, the molecular mechanisms linking MRN activity to ATM are not fully understood. Here, using Xenopus laevis egg extract we show that MRN-dependent processing of DSBs leads to the accumulation of short single-stranded DNA oligonucleotides (ssDNA oligos). The MRN complex isolated from the extract containing DSBs is bound to ssDNA oligos and stimulates ATM activity. Elimination of ssDNA oligos results in rapid extinction of ATM activity. Significantly, ssDNA oligos can be isolated from human cells damaged with ionizing radiation and injection of small synthetic ssDNA oligos into undamaged cells also induces ATM activation. These results suggest that MRN-dependent generation of ssDNA oligos, which constitute a unique signal of ongoing DSB repair not encountered in normal DNA metabolism, stimulates ATM activity.
Jazayeri
Ali
A
Genome Stability Unit, Clare Hall Laboratories, London Research Institute, South Mimms, Herts, UK.
Balestrini
Alessia
A
Garner
Elizabeth
E
Haber
James E
JE
Costanzo
Vincenzo
V
D017766:Acid Anhydride Hydrolases; D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D053903:DNA Breaks, Double-Stranded; D045643:DNA Repair Enzymes / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D000076228:MRE11 Homologue Protein; D009687:Nuclear Proteins / Q000378:metabolism*; D009841:Oligonucleotides / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D014982:Xenopus laevis
D018797:Cell Cycle Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C121766:MRE11 protein, human; C112156:NBN protein, human; D009687:Nuclear Proteins; D009841:Oligonucleotides; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D000076228:MRE11 Homologue Protein; D017766:Acid Anhydride Hydrolases; C112158:RAD50 protein, human; D045643:DNA Repair Enzymes