title: DNA damage-dependent nuclear dynamics of the Mre11 complex.
abstract: The Mre11 complex has been implicated in diverse aspects of the cellular response to DNA damage. We used in situ fractionation of human fibroblasts to carry out cytologic analysis of Mre11 complex proteins in the double-strand break (DSB) response. In situ fractionation removes most nucleoplasmic protein, permitting immunofluorescent localization of proteins that become more avidly bound to nuclear structures after induction of DNA damage. We found that a fraction of the Mre11 complex was bound to promyelocyte leukemia protein bodies in undamaged cells. Within 10 min after gamma irradiation, nuclear retention of the Mre11 complex in small granular foci was observed and persisted until 2 h postirradiation. In light of the previous demonstration that the Mre11 complex associated with ionizing radiation (IR)-induced DSBs, we infer that the protein retained under these conditions was associated with DNA damage. We also observed increased retention of Rad51 following IR treatment, although IR induced Rad51 foci were distinct from Mre11 foci. The ATM kinase, which phosphorylates Nbs1 during activation of the S-phase checkpoint, was not required for the Mre11 complex to associate with DNA damage. These data suggest that the functions of the Mre11 complex in the DSB response are implicitly dependent upon its ability to detect DNA damage.
authors: Laboratory of Genetics, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA.
authors: O K
authors: OK
authors: Mirzoeva
authors: J H
authors: JH
authors: Petrini
mesh_terms: D034961:Antigens, Nuclear; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D002458:Cell Fractionation; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism* / Q000528:radiation effects*; D004249:DNA Damage / Q000235:genetics / Q000528:radiation effects*; D004265:DNA Helicases; D004268:DNA-Binding Proteins / Q000378:metabolism; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; D005347:Fibroblasts; D005455:Fluorescent Antibody Technique; D005656:Fungal Proteins / Q000378:metabolism*; D005720:Gamma Rays; D006801:Humans; D007700:Kinetics; D000072200:Ku Autoantigen; D016296:Mutagenesis / Q000235:genetics / Q000528:radiation effects; D009687:Nuclear Proteins / Q000378:metabolism; D011485:Protein Binding / Q000528:radiation effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D021381:Protein Transport / Q000528:radiation effects; D051135:Rad51 Recombinase; D029701:Saccharomyces cerevisiae Proteins; D025521:Tumor Suppressor Proteins
chemical_list: D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; C094191:MRE11 protein, S cerevisiae; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen