A threshold of endogenous stress is required to engage cellular response to protect against mutagenesis.

Yannick Saintigny (1) , François Chevalier (2) , Anne Bravard (2, 3, 4, 5) , Elodie Dardillac (2, 6, 7, 8, 5) , David Laurent (2) , Sonia Hem (9, 10) , Jordane Dépagne (11) , J Pablo Radicella (2, 3, 4, 5) , Bernard S Lopez (2, 6, 8, 5)

1 Institute of Cellular and Molecular Radiobiology
2 Institute of Cellular and Molecular Radiobiology
3 INSERM - Institut National de la Santé et de la Recherche Médicale
4 UPD7 - Université Paris Diderot - Paris 7
5 Université Paris-Saclay
6 IGR - Institut Gustave Roussy
7 CNRS - Centre National de la Recherche Scientifique
8 UMR 8200 - Stabilité Génétique et Oncogenèse
9 BPMP - Biochimie et Physiologie Moléculaire des Plantes
10 MSPP - Plateforme de Spectrométrie de Masse Protéomique - Mass Spectrometry Proteomics Platform
11 Institute of Cellular and Molecular Radiobiology

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.

Mots clés: gamma-irradiation; mammalian-cells; dna-bas damage; tumorigenesis; proteomics; tumor cell; gamma-irradiation

Mots clés: protéomique; irradiation aux rayons gamma; cellule cancereuse; cellule mammaire; tumorigénèse; activation; protéomique

Domaines: Biologie végétale

Yannick Saintigny, François Chevalier, Anne Bravard, Elodie Dardillac, David Laurent, et al.. A threshold of endogenous stress is required to engage cellular response to protect against mutagenesis.. Scientific Reports, 2016, 6, pp.29412. ⟨10.1038/srep29412⟩. ⟨hal-01594490⟩