title: A threshold of endogenous stress is required to engage cellular response to protect against mutagenesis.
abstract: Endogenous stress represents a major source of genome instability, but is in essence difficult to apprehend. Incorporation of labeled radionuclides into DNA constitutes a tractable model to analyze cellular responses to endogenous attacks. Here we show that incorporation of [(3)H]thymidine into CHO cells generates oxidative-induced mutagenesis, but, with a peak at low doses. Proteomic analysis showed that the cellular response differs between low and high levels of endogenous stress. In particular, these results confirmed the involvement of proteins implicated in redox homeostasis and DNA damage signaling pathways. Induced-mutagenesis was abolished by the anti-oxidant N-acetyl cysteine and plateaued, at high doses, upon exposure to L-buthionine sulfoximine, which represses cellular detoxification. The [(3)H]thymidine-induced mutation spectrum revealed mostly base substitutions, exhibiting a signature specific for low doses (GC > CG and AT > CG). Consistently, the enzymatic activity of the base excision repair protein APE-1 is induced at only medium or high doses. Collectively, the data reveal that a threshold of endogenous stress must be reached to trigger cellular detoxification and DNA repair programs; below this threshold, the consequences of endogenous stress escape cellular surveillance, leading to high levels of mutagenesis. Therefore, low doses of endogenous local stress can jeopardize genome integrity more efficiently than higher doses.
authors.affiliation: Institute of Cellular and Molecular Radiobiology -Commissariat à l'Energie Atomique et aux Energies Alternatives, Fontenay aux Roses, F-92265, France.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Saintigny
authors.affiliation: Institute of Cellular and Molecular Radiobiology -Commissariat à l'Energie Atomique et aux Energies Alternatives, Fontenay aux Roses, F-92265, France.
authors.forename: François
authors.initials: F
authors.lastname: Chevalier
authors.affiliation: Institute of Cellular and Molecular Radiobiology -Commissariat à l'Energie Atomique et aux Energies Alternatives, Fontenay aux Roses, F-92265, France.|UMR967 INSERM/CEA/Universités Paris Diderot et Paris Saclay, Fontenay aux Roses, F-92265, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Bravard
authors.affiliation: Institute of Cellular and Molecular Radiobiology -Commissariat à l'Energie Atomique et aux Energies Alternatives, Fontenay aux Roses, F-92265, France.|UMR 8200 CNRS, Institut de cancérologie Gustave Roussy, Université Paris-Saclay, équipe labélisée par la Ligue bationale contre le Cancer "LIGUE 2014", Villejuif, F-94805, France.
authors.forename: Elodie
authors.initials: E
authors.lastname: Dardillac
authors.affiliation: Institute of Cellular and Molecular Radiobiology -Commissariat à l'Energie Atomique et aux Energies Alternatives, Fontenay aux Roses, F-92265, France.
authors.forename: David
authors.initials: D
authors.lastname: Laurent
authors.affiliation: Plateforme de spectrométrie de masse protéomique - MSPP, Biochimie et physiologie moléculaire des plantes, CNRS, INRA, Montpellier Supagro, Univ. Montpellier, 34060 Montpellier, France.
authors.forename: Sonia
authors.initials: S
authors.lastname: Hem
authors.affiliation: Institute of Cellular and Molecular Radiobiology -Commissariat à l'Energie Atomique et aux Energies Alternatives, Fontenay aux Roses, F-92265, France.
authors.forename: Jordane
authors.initials: J
authors.lastname: Dépagne
authors.affiliation: Institute of Cellular and Molecular Radiobiology -Commissariat à l'Energie Atomique et aux Energies Alternatives, Fontenay aux Roses, F-92265, France.|UMR967 INSERM/CEA/Universités Paris Diderot et Paris Saclay, Fontenay aux Roses, F-92265, France.
authors.forename: J Pablo
authors.initials: JP
authors.lastname: Radicella
authors.affiliation: Institute of Cellular and Molecular Radiobiology -Commissariat à l'Energie Atomique et aux Energies Alternatives, Fontenay aux Roses, F-92265, France.|UMR 8200 CNRS, Institut de cancérologie Gustave Roussy, Université Paris-Saclay, équipe labélisée par la Ligue bationale contre le Cancer "LIGUE 2014", Villejuif, F-94805, France.
authors.forename: Bernard S
authors.initials: BS
authors.lastname: Lopez
mesh_terms: D000818:Animals; D016466:CHO Cells; D003412:Cricetulus; D004249:DNA Damage; D042822:Genomic Instability / Q000235:genetics*; D016296:Mutagenesis; D018384:Oxidative Stress; D040901:Proteomics; D013936:Thymidine / Q000378:metabolism
chemical_list: D013936:Thymidine