Fig. 4: Loss of TGS1 induces RAD51-dependent telomere recombination and APB formation.

a Representative images of combined immunofluorescence using specific anti-TRF2 and anti-PML antibodies in H1299 cells repeatedly transfected with indicated siRNAs for 10 days. b Percentage of PML bodies colocalizing with telomeres (TRF2) per nucleus of experiment shown in a. c Representative images of combined immunofluorescence with anti-TRF2 and anti-PML antibodies in H1299 cells untreated or treated with sinefungin for 3 and 10 days. d Percentage of PML bodies colocalizing with telomeres (TRF2) per nucleus of experiment shown in c. e–g Representative images of combined immunofluorescence using anti-TRF2 and anti-PML antibodies on tumor lung organoids obtained from different patients. Lung tumor organoids were untreated or treated with sinefungin for 10 days. h Percentage of PML bodies colocalizing with telomeres (TRF2) in lung tumor organoid cells. i Representative image of a metaphase spread showing telomeric sister chromatid exchange (T-SCE), as detected by CO-FISH (shown as yellow signals). j Quantification of T-SCE events in H1299 cells transfected with indicated siRNAs. For quantifications shown in b, d, and j, mean values are indicated; whiskers indicate standard deviation. For box-plot diagram (j): middle line represents median; boxes extend from the 25th to 75th percentiles. The whiskers mark the 10th and 90th percentiles. Mean T-SCE values and standard deviation are indicated. N = number of independent experiments. n = number of analyzed nuclei/metaphase spreads. Bars in panels b, d indicate mean values. Red and green, epitopes detected by immunofluorescence; blue, DAPI-stained nuclei. Scale bars in a, c correspond to 1 µm. Scale bars in e–g correspond to 10 µm. A two-tailed Student’s t-test was used to calculate statistical significance; p-values are shown.