title: Ionizing radiation exposure results in up-regulation of Ku70 via a p53/ataxia-telangiectasia-mutated protein-dependent mechanism.
abstract: Genome damaging events, such as gamma-irradiation exposure, result in the induction of pathways that activate DNA repair mechanisms, halt cell cycle progression, and/or trigger apoptosis. We have investigated the effects of gamma-irradiation on cellular levels of the Ku autoantigens. Ku70 and Ku80 have been shown to form a heterodimeric complex that can bind tightly to free DNA ends and activate the protein kinase DNA-PKcs. We have found that irradiation results in an up-regulation of cellular levels of Ku70, but not Ku80, and that this enhanced level of Ku70 accumulates within the nucleus. Further, we uncovered that the postirradiation up-regulation of Ku70 utilizes a mechanism that is dependent on both p53 and damage response protein kinase ATM (ataxia-telangiectasia-mutated); however, the activation of DNA-PK does not require Ku70 up-regulation. These findings suggest that Ku70 up-regulation provides the cell with a means of assuring either proper DNA repair or an appropriate response to DNA damage independent of DNA-PKcs activation.
authors.affiliation: Department of Biochemistry and Molecular Biology, Louisiana State University Medical Center, New Orleans, Louisiana 70112, USA. kbrown1@lsumc.edu
authors.forename: K D
authors.initials: KD
authors.lastname: Brown
authors.forename: T A
authors.initials: TA
authors.lastname: Lataxes
authors.forename: S
authors.initials: S
authors.lastname: Shangary
authors.forename: J L
authors.initials: JL
authors.lastname: Mannino
authors.forename: J F
authors.initials: JF
authors.lastname: Giardina
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.forename: R
authors.initials: R
authors.lastname: Baskaran
mesh_terms: D034961:Antigens, Nuclear; D064007:Ataxia Telangiectasia Mutated Proteins; D001324:Autoantigens / Q000378:metabolism; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D004249:DNA Damage; D004265:DNA Helicases; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000528:radiation effects; D005720:Gamma Rays; D006801:Humans; D000072200:Ku Autoantigen; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism* / Q000528:radiation effects; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D025521:Tumor Suppressor Proteins; D015854:Up-Regulation
chemical_list: D034961:Antigens, Nuclear; D001324:Autoantigens; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen