The relevance of oxidative stress and cytotoxic DNA lesions for spontaneous mutagenesis in non-replicating yeast cells.
Mutations arising during times of cell cycle-arrest may considerably contribute to aging and cancerogenesis. Endogenous oxidative stress could be one of the major triggers for these mutations. We used Saccharomyces cerevisiae cells, arrested by starvation for the essential amino acid lysine, to study the occurrence of reactive oxygen species (ROS), abasic (AP) sites and double strand breaks (DSBs). Furthermore, we analyzed the mutation frequencies in resting wild type cells and in cells deficient for Apn1 (with an impaired base excision repair) or Dnl4 (with an inactivated non-homologous end joining (NHEJ) DSB repair pathway) by monitoring reversions of an auxotrophy-causing frameshift in the LYS2 gene. By fluorescence methods, we observed a distinct increase of ROS-affected cells in the course of starvation-induced cell cycle-arrest. In addition, we could reveal that AP sites and DSBs accumulated under these conditions. The frequency of spontaneous frameshift mutations in wild type cells was decreased to 50% upon addition of 6mM N-acetyl cysteine. However, this radical scavenger had no effect in Dnl4-deficient cells. Our results support the hypothesis that (via an active NHEJ DSB repair pathway) the incidence of spontaneous frameshift mutations in a cell cycle-arrested state is considerably governed by oxidative stress.
Steinboeck
Ferdinand
F
Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, Borschkegasse 8a, A-1090 Vienna, Austria. ferdinand.steinboeck@meduniwien.ac.at
Hubmann
Maria
M
Bogusch
Alexandra
A
Dorninger
Petra
P
Lengheimer
Theresia
T
Heidenreich
Erich
E
D002453:Cell Cycle; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage; D045643:DNA Repair Enzymes / Q000235:genetics; D004706:Endodeoxyribonucleases / Q000235:genetics; D016368:Frameshift Mutation; D008239:Lysine / Q000378:metabolism; D018384:Oxidative Stress / Q000235:genetics*; D010750:Phosphoproteins / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics
D010750:Phosphoproteins; D029701:Saccharomyces cerevisiae Proteins; D004706:Endodeoxyribonucleases; C083274:Apn1 protein, S cerevisiae; D045643:DNA Repair Enzymes; D008239:Lysine