Figure 8.

Transient transfection assay of effects of coactivators and corepressors on CYP24A1 and CYP7A1 promoter reporter activity. A, Reporter assays of human CYP24A1 promoter/luciferase reporter, phCYP24A1/-1200-Luc. B, Reporter assays of human CYP7A1 promoter/luciferase reporter, ph-1887Luc. Reporter plasmid (0.2 μg) was cotransfected with VDR (0.1 μg) and RXRα (0.1 μg) expression plasmids or control plasmid (pcDNA3.1), and with expression plasmid (0.1 μg) for PGC-1α, NCoR-1, and SMRT, as indicated, into HepG2 cells for 24 h, followed by treatment with 1α,25(OH)₂-D₃ (5 nm), or LCA-acetate (10 μm), or vehicle (EtOH) for an additional 24 h. The luciferase activities were assayed as described in Materials and Methods. Each experiment was done in triplicate and expressed as mean ± sd. *, Statistically significant difference (P < 0.05, n = 3) vs. vehicle control with the same cotransfection. #, Statistically significant difference (P < 0.05, n = 3) vs. pcDNA3 cotransfected sample with the same treatment. RLU, Relative light units.