Figure 2. RAP1 prevents telomere fusions in senescent cells.

• A
  Number of telomere fusions performed by PCR using 3 subtelomeric primers in the same reaction (16p1, 21q1, and XpYpM). The primer 16p1 is able to bind the subtelomeric region of 1p 9q, 12p, 15q, 16p, XqYq, and the interstitial 2q14 region; the 21q1 primer binds the subtelomeric region of 1q, 2q, 5q, 6q, 6p, 8p, 10q, 13q, 19p, 19q, 21q, 22q, and the interstitial 2q13 site. The PCR‐fusion assay was performed in MRC‐5 primary fibroblasts of different population doublings (PD) with or without depletion of RAP1 (shRAP1 or shControl, respectively). Lentiviral infection was performed for 10 days. Data represent mean ± SD of three biological replicates. Statistical analyses were performed using Mann–Whitney U‐test (**P < 0.001; ***P < 0.0001).
• B
  Southern blotting showing the hybridization of the 16p probe for the conditions described in (A). Number of fusions per 1 μg of DNA is shown at the bottom of the gels.
• C, D
  Number of fusions per 1 μg of DNA in MRC‐5 senescent cells. Lentiviral transfections with shRNAs were carried out for 10 days while transfections with siRNAs for 6 days (two subsequent transfections of 3 days each). Representative Southern blot membranes hybridized with the 16p probe are shown. Data represent mean ± SD of three biological replicates. Statistical analyses were performed using Mann–Whitney U‐test (*P < 0.05; **P < 0.001; ***P < 0.0001).