ATM-dependent phosphorylation of MRE11 controls extent of resection during homology directed repair by signalling through Exonuclease 1

We report here that MRE11 is phosphorylated by ataxia-telangiectasia mutated at S676 and S678 in response to agents that induce DNA double strand breaks, is dependent on the presence of NBS1, and does not affect the association of members of the complex or ATM activation

Amanda W. Kijas; Yi Chieh Lim; Emma Bolderson; Karen Cerosaletti; Magtouf Gatei; Burkhard Jakob; Frank Tobias; Gisela Taucher-Scholz; Nuri Gueven; Greg Oakley; Patrick Concannon; Ernst Wolvetang; Kum Kum Khanna; Lisa Wiesmüller; Martin F. Lavin

2015

Scholarcy highlights

  • Exposure of cells to DNA damage leads to a variety of lesions of which DNA double strand breaks represent the greatest threat to the integrity and survival of cells
  • To confirm that the band detected by the phospho-specific antibody was phosphorylated, immunoprecipitates were exposed to ␭ phosphatase which led to a loss of signal, supporting phosphorylation of MRE11
  • As there was no defect in the localization of the mutant MRE11S676AS67A to damaged chromatin, but these cells displayed an increase in chromosomal aberrations and decrease in survival after induction of DNA DSB, we performed a kinetic of ␥ H2AX foci appearance and loss with time as a measure of break repair
  • ataxia-telangiectasia mutated-dependent phosphorylation of NBS1 occurs on two sites, S282 and S343 and mutation at these sites prevents signalling to downstream substrates linked to DNA repair, cell cycle checkpoint activation and cell survival
  • A single site of ATM-dependent phosphorylation has been identified on the second member of the complex, RAD50. Phosphorylation at this site is required for correction of cell cycle checkpoint activation, DNA repair and survival in RAD50-deficient cells in response to DNA DSB
  • The corresponding MRE11 phosphosite mutant enables normal ATM signalling through substrates such as SMC1, the phosphorylation of which is implicated in cell cycle control, genome stability and cell survival
  • The characterization of the non-phosphorylatable mutant form of MRE11 has shed light on the key role of this phosphorylation in controlling the extent of resection enabling successful homologous recombination by controlling ataxia-telangiectasia mutated’s phosphorylation of Exonuclease 1 and provides a separation of function mutation enabling a distinction between the early role of MRE11 in activating ATM from its more downstream roles in controlling resection during homology directed repair

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