Fig. 3.

Oxysterol 22(R)-OHC-mediated up-regulation of BSEP promoter activity was achieved through nuclear receptor FXR but not LXR or PXR. Huh 7 cells were transiently transfected with 100 ng of BSEP promoter reporter pBSEP-Luc or other nuclear receptor target reporters, 100 ng of expression plasmid for either nuclear receptor LXRα or LXRβ, PXR, and FXR, and 10 ng of the null-Renilla luciferase plasmid as an internal control. Sixteen hours post-transfection, cells were treated with 0.1% ETOH, 10 μM 22(R)-OHC, 0.1% DMSO, 10 μM CDCA, and RIF for 30 h. Luciferase activities were measured by the Dual-Luciferase Reporter assay system. The firefly luminescence was normalized based on the Renilla luminescence signal. Data are presented as mean ± S.D. of at least three separate experiments. A, cells were cotransfected with LXRα and pBSEP-Luc or pTK-Luc-2LXRE-3 or pGL-TK-2610 (LXR). B, cells were cotransfected with LXRβ and pBSEP-Luc or pTK-Luc-2LXRE-3 or pGL-TK-2610 (LXR). C, cells were cotransfected with PXR and pBSEP-Luc or pCYP3A4DP-Luc. D, cells were cotransfected with FXR and pBSEP-Luc or pCYP3A4DP-Luc.