Fig. 3 |. POT1B and BRD2 are required for telomere protection in the absence of TRF2.

a, Representative images of metaphases from TRF2-depleted and control ES cells of indicated genotypes; percentages of telomeres fused for each genotype are shown in the top right corner. Scale bars, 10 μm. b, Scatter plot representing the distribution of telomeric fusions. Each dot represents the percentage of telomeres fused in one metaphase spread; for detailed information, see Supplementary Table 1, Source Data for Fig. 3. c, Representative fluorescence-activated cell sorting (FACS) plots (y axes, number of cells detected; x axes, intensity of propidium iodide (PI) staining), showing the cell-cycle profiles of ES cells of indicated genotypes. The G1 phase of the cell cycle is marked in blue. d, Representative IF–FISH for 53BP1 (red) and telomeres (green) in ES cells of the indicated genotype and treatment. Scale bar, 4 μm. e, Quantification of the percentage of cells with more than 10 53BP1 foci colocalizing with telomeres, detected as in d. f, Quantification of the percentage of cells with more than 10 γH2AX foci colocalizing with telomeres, detected as in d. g, Representative western blotting analysis of ES cells untreated (−) or treated with OHT (+) and collected 4 days after treatment. Where indicated, cells were treated with an ATM inhibitor (ATMi). All data panels in the figure are representative of three experiments. NS, non-significant (P ≥ 0.05), *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, one-way ANOVA.