Apn1 AP-endonuclease is essential for the repair of oxidatively damaged DNA bases in yeast frataxin-deficient cells

• Published in: Human molecular genetics 2012-09, Vol.21 (18), p.4060-4072
• Main Authors: LEFEVRE, Sophie, BROSSAS, Caroline, AUCHERE, Françoise, BOGGETTO, Nicole, CAMADRO, Jean-Michel, SANTOS, Renata
• Format: Article
• Language: English
• Subjects: Alkylating Agents - pharmacology; Anaerobiosis; Antioxidants - metabolism; Apoptosis; Biochemistry, Molecular Biology; Biological and medical sciences; Cell Cycle Checkpoints; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; DNA Breaks, Double-Stranded; DNA Repair; DNA Repair Enzymes - genetics; DNA Repair Enzymes - metabolism; DNA Repair Enzymes - physiology; DNA, Fungal - genetics; DNA, Fungal - metabolism; DNA, Mitochondrial - genetics; DNA, Mitochondrial - metabolism; Endodeoxyribonucleases - physiology; Frataxin; Friedreich Ataxia - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression; Gene Expression Regulation, Fungal; Genetics of eukaryotes. Biological and molecular evolution; Glutathione - metabolism; Humans; Hydrogen Peroxide - pharmacology; Iron-Binding Proteins - genetics; Iron-Binding Proteins - metabolism; Life Sciences; Medical sciences; Methyl Methanesulfonate - pharmacology; Microbial Viability; Molecular and cellular biology; Molecular biology; Molecular genetics; Mutagenesis - drug effects; Mutagenesis. Repair; Neurology; Oxidants - pharmacology; Oxidation-Reduction; Oxidative Stress; Reactive Oxygen Species - metabolism; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - physiology
• ISSN: 0964-6906; 1460-2083
• DOI: 10.1093/hmg/dds230

Frataxin deficiency results in mitochondrial dysfunction and oxidative stress and it is the cause of the hereditary neurodegenerative disease Friedreich ataxia (FA). Here, we present evidence that one of the pleiotropic effects of oxidative stress in frataxin-deficient yeast cells (Δyfh1 mutant) is damage to nuclear DNA and that repair requires the Apn1 AP-endonuclease of the base excision repair pathway. Major phenotypes of Δyfh1 cells are respiratory deficit, disturbed iron homeostasis and sensitivity to oxidants. These phenotypes are weak or absent under anaerobiosis. We show here that exposure of anaerobically grown Δyfh1 cells to oxygen leads to down-regulation of antioxidant defenses, increase in reactive oxygen species, delay in G1- and S-phases of the cell cycle and damage to mitochondrial and nuclear DNA. Nuclear DNA lesions in Δyfh1 cells are primarily caused by oxidized bases and single-strand breaks that can be detected 15-30 min after oxygen exposition. The Apn1 enzyme is essential for the repair of the DNA lesions in Δyfh1 cells. Compared with Δyfh1, the double Δyfh1Δapn1 mutant shows growth impairment, increased mutagenesis and extreme sensitivity to H(2)O(2). On the contrary, overexpression of the APN1 gene in Δyfh1 cells decreases spontaneous and induced mutagenesis. Our results show that frataxin deficiency in yeast cells leads to increased DNA base oxidation and requirement of Apn1 for repair, suggesting that DNA damage and repair could be important features in FA disease progression.