Figure 5.

p53 negatively regulates PP5 expression. A, two putative consensus p53-binding sites were identified in the PP5 gene promoter region, and alignment analyses demonstrated that these p53-binding sites are highly conserved among mouse, rat, human, and chimpanzee. EX1–EX3, exons 1–3. B and C, Western blot analyses of the up-regulation of PP5 in p53 KO cells (B) and tissues (C). D, in p53 KO MEF cells, PP5 expression was repressed following p53 transfection. E and F, Western blot and real-time quantitative RT-PCR analyses of WT and pp5^−/− mice liver samples. G, the binding of p53 to the pp5 promoter was determined by a ChIP assay. IgG and agarose beads served as negative controls. H, luciferase (Luc) assays demonstrated that the pp5 promoter (pro) was negatively regulated by p53 but not by mutant p53. Values represent the means ± S.D. (error bars) of three independent experiments. ** represents p < 0.01, and *** represents p < 0.001. GAPDH, glyceraldehyde-3-phosphate dehydrogenase.