Figure 2.

Activation of p53 upon BuGZ depletion leads to apoptosis or senescence. (A) Up-regulation of p53 after 48 h of BuGZ siRNA treatment. Loading control, α-tubulin. (B) Increased phospho-p53 (Ser15) in the nuclei of BuGZ-depleted cells (arrowheads). BuGZ-positive (arrows) and phospho-p53 negative cells (arrows and white broken circles) are indicated. Cells were assayed 48 h after siRNA treatment. Bars, 10 µm. (C) Inhibition of p53 by PFT-α increased the numbers of viable BuGZ-depleted cells. Error bars indicate SD. Student’s t test: **, P < 0.01 from three independent experiments. (D–F) p53 RNAi in HFFs repressed senescence induced by BuGZ knockdown. HFFs were infected with lentivirus to express the indicated shRNAs. Western blotting (D) and quantification (E) of SA-β-gal staining (F) were performed at 30 d after infection. Arrowheads in F represent the SA-β-gal–positive staining cells. Bar, 100 µm. Error bars indicate SEM. Student’s t test: *, P < 0.05; **, P < 0.01 from three independent experiments.