Mre11 Is Essential for the Removal of Lethal Topoisomerase 2 Covalent Cleavage Complexes.
The Mre11/Rad50/Nbs1 complex initiates double-strand break repair by homologous recombination (HR). Loss of Mre11 or its nuclease activity in mouse cells is known to cause genome aberrations and cellular senescence, although the molecular basis for this phenotype is not clear. To identify the origin of these defects, we characterized Mre11-deficient (MRE11-/-) and nuclease-deficient Mre11 (MRE11-/H129N) chicken DT40 and human lymphoblast cell lines. These cells exhibit increased spontaneous chromosomal DSBs and extreme sensitivity to topoisomerase 2 poisons. The defects in Mre11 compromise the repair of etoposide-induced Top2-DNA covalent complexes, and MRE11-/-and MRE11-/H129Ncells accumulate high levels of Top2 covalent conjugates even in the absence of exogenous damage. We demonstrate that both the genome instability and mortality of MRE11-/-and MRE11-/H129Ncells are significantly reversed by overexpression of Tdp2, an enzyme that eliminates covalent Top2 conjugates; thus, the essential role of Mre11 nuclease activity is likely to remove these lesions.
Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
Nguyen Ngoc
NN
Hoa
Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
Tsubasa
T
Shimizu
Leibniz Institute for Age Research-Fritz Lipmann Institute, Beutenbergstrasse 11, 07745 Jena, Germany.
Zhong Wei
ZW
Zhou
Leibniz Institute for Age Research-Fritz Lipmann Institute, Beutenbergstrasse 11, 07745 Jena, Germany.
Zhao-Qi
ZQ
Wang
Howard Hughes Medical Institute, Department of Molecular Biosciences, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA.
Rajashree A
RA
Deshpande
Howard Hughes Medical Institute, Department of Molecular Biosciences, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA.
Tanya T
TT
Paull
Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
Salma
S
Akter
Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
Masataka
M
Tsuda
Department of Neurogenomics, Graduate School of Medicine, Dentistry and Pharmaceutical Science, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
Ryohei
R
Furuta
Department of Neurogenomics, Graduate School of Medicine, Dentistry and Pharmaceutical Science, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
Ken
K
Tsutsui
Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
Shunichi
S
Takeda
Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan. Electronic address: hiroysasa@rg.med.kyoto-u.ac.jp.
Hiroyuki
H
Sasanuma
D017766:Acid Anhydride Hydrolases; D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics* / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002645:Chickens; D004247:DNA / Q000235:genetics* / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects*; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D005047:Etoposide / Q000494:pharmacology; D005786:Gene Expression Regulation; D042822:Genomic Instability / Q000187:drug effects; D006801:Humans; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000076228:MRE11 Homologue Protein; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases; D000075223:Poly-ADP-Ribose Binding Proteins; D059767:Recombinational DNA Repair / Q000187:drug effects*; D015398:Signal Transduction; D059005:Topoisomerase II Inhibitors / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D000951:Antigens, Neoplasm; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C121766:MRE11 protein, human; C112156:NBN protein, human; D009687:Nuclear Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D059005:Topoisomerase II Inhibitors; D014157:Transcription Factors; D005047:Etoposide; D004247:DNA; D000076228:MRE11 Homologue Protein; D010727:Phosphoric Diester Hydrolases; C474866:TDP2 protein, human; D017766:Acid Anhydride Hydrolases; C112158:RAD50 protein, human; D004250:DNA Topoisomerases, Type II; C000618811:TOP2A protein, human; C000618812:Top2a protein, mouse; D045643:DNA Repair Enzymes
Mre11 and nonhomologous end joining; etoposide