Human telomeric protein TRF2 associates with genomic double-strand breaks as an early response to DNA damage.
DNA damage surveillance networks in human cells can activate DNA repair, cell cycle checkpoints and apoptosis in response to fewer than four double-strand breaks (DSBs) per genome. These same networks tolerate telomeres, in part because the protein TRF2 prevents recognition of telomeric ends as DSBs by facilitating their organization into T loops. We now show that TRF2 associates with photo-induced DSBs in nontelomeric DNA in human fibroblasts within 2 s of irradiation. Unlike gammaH2AX, a common marker for DSB damage, TRF2 forms transient foci that colocalize closely with DSBs. The TRF2 DSB response requires the TRF2 basic domain but not its Myb domain and occurs in the absence of functional ATM and DNA-PK protein kinases, MRE11/Rad50/NBS1 complex and Ku70, WRN and BLM repair proteins. Furthermore, overexpression of TRF2 inhibits DSB-induced phosphorylation of ATM signaling targets. Our results implicate TRF2 in an initial stage of DSB recognition and processing that occurs before association of ATM with DSBs and activation of the ATM-dependent DSB response network.
Bradshaw
Paul S
PS
Program in Genetics and Genomic Biology, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada.
Stavropoulos
Dimitrios J
DJ
Meyn
M Stephen
MS
D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D002461:Cell Line, Transformed; D004247:DNA / Q000528:radiation effects; D004249:DNA Damage; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D005347:Fibroblasts; D006657:Histones / Q000032:analysis; D006801:Humans; D008957:Models, Genetic; D008968:Molecular Conformation; D009687:Nuclear Proteins; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D035341:Telomeric Repeat Binding Protein 2 / Q000378:metabolism*; D025521:Tumor Suppressor Proteins
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; C112156:NBN protein, human; D009687:Nuclear Proteins; D035341:Telomeric Repeat Binding Protein 2; D025521:Tumor Suppressor Proteins; D004247:DNA; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases