Figure 5.

CIITA promoter IV is highly methylated in HepG2 hepatocarcinoma cells.

(a) Schematic representation of the human CIITA promoter IV region used for PCR amplification of bisulfite converted DNA. The sequence, including GAS, E-box and IRF1 consensus elements, was amplified by PCR in two sub regions (a: from position −334 to −160; b: from position −209 to + 99), using specific primers as indicated in Materials and Methods. The numbers indicate the relative distance upstream of the transcriptional start site (black arrow). Vertical bars in the upper line indicate CpG dinucleotide. (b) CpG methylation of the human CIITA promoter IV selected region in RA and HepG2 cells treated with 500U/ml of IFNγ or its vehicle for 3 days. The methylation status of CpGs in the promoter region was monitored by bisulfite analysis. The filled and open circles represent the methylated and unmethylated CpG dinucleotides, respectively. A mean of 4 separate clones was analyzed for each region. High methylation was observed in HepG2 cells, independently of IFNγ treatment.