Figure 6. PPARγ positively regulates Bsep transcription through direct binding to the Bsep promoter. (A) HepG2 cells were incubated with TEC for 24 h. The protein level of Bsep and PPARγ were detected by western blotting, n=5. (B) HepG2 cells were incubated with TEC and/or GW1912 (GW9662) for 24 h, and the mRNA level of Bsep was determined by qRT-PCR, n=5. (C) HepG2 cells were transfected with shPPARγ for 24 h, then treated with TEC for another 24 h, and the mRNA level of Bsep was determined by qRT-PCR, n=5. (D) HepG2 cells were incubated with various concentrations of TEC for 24 h, and PPARγ transcriptional activity was measured by luciferase assay, n=5. (E) Luciferase reporter assays of a series of Bsep promoter fragments cloned into luciferase reporter gene (Luc1 to Luc3) with or without PPARγ-transfection of HepG2 cells, n=5. (F) Chromatin immunoprecipitation (ChIP) assay–qPCR analysis in the region −3218 bp/−2178 bp of the Bsep promoter in PPARγ-transfected HepG2 cells with or without TEC treatment. IgG, immunoglobulin G, n=5. (G) Depiction of the predicted PPARγ binding sites at -2560 to -2541 base pairs (bp) in the human Bsep gene. *p<0.05. The data represent the mean ± SD.