Fig. 2: PARP2 depletion prevents replication stress mediated telomere fragility.

a Schematic of the chronic induction of ₁O². Arrows indicate the days when cells were passaged or harvested and not treated with dye and light (created with BioRender.com). b Mean projection slopes obtained from the population doubling curves of 4 to 8 independent experiments. P-values were obtained using two-sided Welch’s two-sample t-test. Minima, maxima, bounds of box and whiskers and percentile are indicated in the Source Data file. c Representative images of telomere FISH on metaphase chromosomes 24 h after the 18th dye and light exposure. Telomeric signal-free ends and fragile telomeres (white stars) are indicated. d Quantification of telomeric signal-free ends 24 h after the last dye and light exposure treatment (N18). Each dot represents a metaphase. At least 30 metaphases were analyzed per experiment. Red bars represent mean ± SD from n metaphases analyzed from four independent experiments. P-values were obtained using ordinary one-way ANOVA. e Quantification of fragile telomeres 24 h after the last dye and light exposure treatment (N18). Each dot represents a metaphase. At least 30 metaphases were analyzed per experiment. Red bars represent mean ± SD from n metaphases analyzed from four independent experiments. P-values were obtained using ordinary one-way ANOVA. f Western blot analysis of BLM in HelaFAP, PARP1KO, PARP2KO, and PARP1/2KO cells treated with 50 nM BLM siRNA for 48 h. Actin was used as a loading control. g Quantification of fragile telomeres detected by FISH in HelaFAP, PARP1KO, PARP2KO, and PARP1/2KO after knockdown of BLM with siRNA. Each dot represents a metaphase. At least 20 to 30 metaphases were analyzed per experiment. Red bars represent mean ± SD from n metaphases analyzed from two independent experiments. P-values were obtained using ordinary one-way ANOVA. Source data are provided as a Source Data file.