FIGURE 4.

Synergistic CYP2B6 transactivation by C/EBPα, HNF4α, and CAR requires both proximal and distal promoter sequences. The −1.8 kb CYP2B6 promoter region was dissected into several chimeric reporter constructs. HepG2 cells were infected with the recombinant adenoviral vectors individually (A) or combined (B) for 24 h. Then cells were transfected with the CYP2B6 promoter constructs. At 48 h postinfection, cells were treated with 500 nm CITCO, and at 72 h postinfection, cells were lysed, and both firefly and R. reniformis luciferase activities were determined. Bars, mean ± S.D. of six independent experiments, expressed as firefly/Renilla luciferase activity ratios. The symbols in the left-hand diagrams denote OA-responsive module (ellipse) and PBREM (square).