Fig 5.

PNR-stimulated p53 acetylation correlates with p53 transactivation and accumulation in HeLa cells. (A) PNR stimulates p53 acetylation. Total p53 and acetylated p53 (Ac-p53) levels were measured by immunoblotting with anti-p53 and anti-Ac-p53 antibodies, respectively. Acetylations by the indicated acetyltransferases, which were measured with their specific anti-Ac-p53 antibodies, can occur at multiple lysines of p53. The numbers below each band represent the levels of Ac-p53 per unit of total p53 normalized to that in sample 2. GFP was used as a transfection control. (B and C) Coexpressing p53 deacetylase SIRT1 inhibits PNR-mediated stimulation of p53 accumulation and transactivation. (B) SIRT1 inhibits PNR-mediated p53 acetylation and accumulation in a dose-dependent fashion. Ac-p53, total p53, PNR, and GFP were measured as described for panel A. Endogenous p21 and β-actin protein levels were also measured. SIRT1 abolished the PNR-mediated increase in p21 protein accumulation. (C) SIRT1 inhibited PNR-mediated stimulation of p53RE-FLuc expression in a dose-dependent fashion in a 96-well plate.