Fig. 4: RNaseH1 overexpression exacerbates leading telomere fragility in PCS^LT cells.

A DNA:RNA immunoprecipitation (IP) analysis using S9.6 antibody in extracts from PCS^ST and PCS^LT-EV cells. IP and input samples were analyzed by qPCR with primer sets amplifying telomeric DNA. Values in IP were normalized first to input and then to PCS^LT-EV. Values obtained for control experiments with IgG were subtracted. n = 3 independent biological replicates. Mean ± SEM. Two-tailed ratio paired t-test. B Western blot of cell extracts from PCS^LT cells transduced with pLHCX empty vector (EV), pLHCX-RNaseH1-Myc (RH1) or pLHCX-catalytically dead RNaseH1-Myc (RH1-CD), probed for Myc and Actin. Representative of n = 6 biological replicates. C Lagging (green) and leading (black) telomere fragility assessed by CO-FISH in PCS^LT cells transduced with EV, RH1, or RH1-CD. A minimum of 11500 chromosome ends were analyzed, based on n metaphase spreads collected from three independent biological replicates. Boxplot: Min, 1st quartile, Median, 3rd quartile, and Max. Kruskal–Wallis tests. D Left: Representative images for Telo-FISH (red)/IF experiments targeting RAD51 (cyan) and RPA (green) in PCS^LT cells transduced with EV, RH1, or RH1-CD. Right: Co-localization events between telomeres and RAD51 (cyan) or RPA (green). n nuclei were analyzed from three independent biological replicates. Median in red, quartiles in orange. Kruskal–Wallis tests. Source data are provided as a Source Data file.