Figure 1

Telomeres are a hotspot for oxidation due to cell cycle ROS production. (A) DNA from U2OS cells was used to measure 8-oxoG levels at the 36B4 locus or telomeric DNA. Bars show the mean and the standard error of the mean (SEM) from 3 technical replicates from 6 independent experiments for each condition (Mann–Whitney test; **P < 0.01). (B) OGG1-GFP pulldown followed by chromatin immunoprecipitation coupled to PCR for amplification of either 36B4 locus or the telomere regions in the U2OS parental and U2OS OGG1-GFP cell lines. Data are the average of 3 technical replicates from 2 independent experiments. Statistical significance was determined using (Mann–Whitney test; **P < 0.01. (C) Sorted DNA from different cell cycle phases (G1, S, or G2/M) from U2OS cells was used to evaluate 8-oxoG levels at the 36B4 locus or telomeric DNA along the cell cycle. Bars show the mean and the SEM from 3 technical replicates from 6 independent experiments for each condition (two-sided T-test; *** P < 0.001). (D) Quantification of OGG1 protein expression level in U2OS cells along the cell cycle. Actin levels were used to normalize for protein loading. Immunoblotting was performed in triplicate. Statistical significance was determined by two-sided T-test (P > 0.05, ns: not significant). The full-length blots are presented in Supplementary Figure S2 (E) Percentage of cells with intracellular ROS levels above the median of the whole U2OS population is represented in different cell cycle stages (G1, S, or G2/M). Data are average ± SEM from single measures from 3 independent experiments. Significant differences were addressed by two-sided T-test (P > 0.05, ns: not significant).