title: ATM-dependent phosphorylation of MRE11 controls extent of resection during homology directed repair by signalling through Exonuclease 1.
abstract: The MRE11/RAD50/NBS1 (MRN) complex plays a central role as a sensor of DNA double strand breaks (DSB) and is responsible for the efficient activation of ataxia-telangiectasia mutated (ATM) kinase. Once activated ATM in turn phosphorylates RAD50 and NBS1, important for cell cycle control, DNA repair and cell survival. We report here that MRE11 is also phosphorylated by ATM at S676 and S678 in response to agents that induce DNA DSB, is dependent on the presence of NBS1, and does not affect the association of members of the complex or ATM activation. A phosphosite mutant (MRE11S676AS678A) cell line showed decreased cell survival and increased chromosomal aberrations after radiation exposure indicating a defect in DNA repair. Use of GFP-based DNA repair reporter substrates in MRE11S676AS678A cells revealed a defect in homology directed repair (HDR) but single strand annealing was not affected. More detailed investigation revealed that MRE11S676AS678A cells resected DNA ends to a greater extent at sites undergoing HDR. Furthermore, while ATM-dependent phosphorylation of Kap1 and SMC1 was normal in MRE11S676AS678A cells, there was no phosphorylation of Exonuclease 1 consistent with the defect in HDR. These results describe a novel role for ATM-dependent phosphorylation of MRE11 in limiting the extent of resection mediated through Exonuclease 1.
authors.affiliation: The University of Queensland, UQ Centre for Clinical Research, University of Queensland, Brisbane, Queensland 4029, Australia.
authors.forename: Amanda W
authors.initials: AW
authors.lastname: Kijas
authors.affiliation: Brain Cancer Research Unit, QIMR Berghofer Medical Research Institute, Brisbane, Queensland 4029, Australia.
authors.forename: Yi Chieh
authors.initials: YC
authors.lastname: Lim
authors.affiliation: Genome Stability Laboratory, Translational Research Institute, Queensland University of Technology, Queensland 4102, Australia.
authors.forename: Emma
authors.initials: E
authors.lastname: Bolderson
authors.affiliation: Translational Research Program, Benaroya Research Institute, Seattle, WA 981010, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Cerosaletti
authors.affiliation: The University of Queensland, UQ Centre for Clinical Research, University of Queensland, Brisbane, Queensland 4029, Australia.
authors.forename: Magtouf
authors.initials: M
authors.lastname: Gatei
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt 64291, Germany.
authors.forename: Burkhard
authors.initials: B
authors.lastname: Jakob
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt 64291, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Tobias
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt 64291, Germany.
authors.forename: Gisela
authors.initials: G
authors.lastname: Taucher-Scholz
authors.affiliation: School of Medicine, Faculty of Health, University of Tasmania, Hobart, Tasmania 7001, Australia.
authors.forename: Nuri
authors.initials: N
authors.lastname: Gueven
authors.affiliation: University of Nebraska College of Dentistry, Lincoln, NE 68583-0740, USA.
authors.forename: Greg
authors.initials: G
authors.lastname: Oakley
authors.affiliation: Genetics Institute, University of Florida, Gainesville, Florida, FL 3261, USA.
authors.forename: Patrick
authors.initials: P
authors.lastname: Concannon
authors.affiliation: Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane 4072, Australia.
authors.forename: Ernst
authors.initials: E
authors.lastname: Wolvetang
authors.affiliation: Signal transduction, QIMR Berghofer Medical Research Institute, Brisbane, Queensland 4029, Australia.
authors.forename: Kum Kum
authors.initials: KK
authors.lastname: Khanna
authors.affiliation: Department of Obstetrics and Gynaecology, University of Ulm, Ulm 89075, Germany.
authors.forename: Lisa
authors.initials: L
authors.lastname: Wiesmüller
authors.affiliation: The University of Queensland, UQ Centre for Clinical Research, University of Queensland, Brisbane, Queensland 4029, Australia m.lavin@uq.edu.au.
authors.forename: Martin F
authors.initials: MF
authors.lastname: Lavin
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism*; D002460:Cell Line; D045744:Cell Line, Tumor; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000378:metabolism*; D006801:Humans; D010766:Phosphorylation; D011839:Radiation, Ionizing; D059767:Recombinational DNA Repair; D015398:Signal Transduction
chemical_list: D004268:DNA-Binding Proteins; D064007:Ataxia Telangiectasia Mutated Proteins; D005090:Exodeoxyribonucleases; C028450:exodeoxyribonuclease I