Schematic overview of the strategy used in this study and time course of the expression of adenoviral-encoded genes. (A) Adenoviral vectors harboring the genes of targeted DNA and H3K9 methyltransferases were used to infect SKOV3 cells. (B) The enzymes were fused to a zinc finger domain which binds a site in the promoter of the VEGF-A gene. The schematic picture of the VEGF-A promoter shows the gene structure in dark blue, an annotated CpG island in green, the zinc finger-binding site in red, and the amplicons used for bisulfite DNA methylation analysis and ChIP-qPCR in light blue and black, respectively. Additional ChIP-qPCR amplicons located outside of the region shown here are indicated in Figure 3. Transcription factor-binding sites to the VEGF-A promoter are indicated in Additional file 1: Figure S1A. (C) The chimeric zinc finger-fused DNA and H3K9 methyltransferases are targeted to the VEGF-A promoter where they introduce DNA or histone H3K9 methylation. (D) Time course of the expression of adenoviral vector-encoded genes after cell infection. The adenoviral vector also expresses GFP to allow for the FACS analysis of infection yields and follow the expression levels of virus-encoded genes. The time-course of GFP fluorescence of all data sets analysed in this respect was similar, and its average is shown here. The data shows averages and corresponding standard errors of the mean of 21 experiments. GFP, green fluorescence protein; ZF, zinc finger; HKMT, histone lysine methyltransferase; DNMT, DNA methyltransferase; d, days; bp, base pair; qPCR, quantitative PCR; VEGF-A, vascular endothelial growth factor A.