Fig. 4

The p53R248Q and p53R273C mutants associate with chromatin and induce histone H3 and H4 acetylation in HER2 promoter proximal region. Saos-2 cells stably transfected with p53R248Q, p53R273C or empty vector were analyzed by Chromatin immunoprecipitation (ChIP) as described in the Materials and Methods. Antibodies against acetylated histone H3, H4, p53 protein and IgG as non-relevant antibody were used for the immunoprecipitation. a Shows a graphic representation of the regions encompassed by the primers used for ChIP assay. Precipitated DNA was amplified with primers described in Additional file 2: Table S2. HER2a (b) region from − 22 to − 75 bp; HER2b (c) -217 bp, and (d) region with not known HER2 regulatory sequences. Relative amounts of acetylated H3 and H4 histones, as well as p53 interaction with HER2 promoter regions were determined on the precipitated DNA by quantitative PCR (qPCR). Normalized data were calculated relative to each primer set (b-d), comparing p52R248Q or p53R273C vs IgG ChIP 1.0% input sample. The results of Fold Enrichment are reported as the mean ± SEM of three independent experiments. Statistical analysis was performed with t-student test by comparing the results obtained for the Fold Enrichment in Saos-2 cells transfected with p53R48Q or p53R273C against empty vector transfected cells: * p < 0.05