Fig 3. Screening for bPXR- and bCAR-responsive regions in CYP3A28 promoter.

A series of CYP3A28 luciferase reporter gene constructs (PP, lnPP, PP+F1, PP+F2, PP+F3, PP+F4, PP+F5) was prepared as described in S1 File. Numbers indicate the positions relative to the transcriptional start site. HepG2 cells were transfected with the control reporter pCMVβ (600 ng/well), each reporter plasmids or PBREM-tk-luc (PBREM) and CYP3A4-XREM-luc (XREM) or with negative control reporter pGL4.10-luc (500 ng/well) and either bCAR and bPXR expression plasmids or pCI-neo empty vector (100 ng/well). After transfection, cells were treated with vehicle (0.1% DMSO) or SR12813 (10 μM) for 24 hours, and reporter activities were measured. Firefly luciferase activities were normalized with β-galactosidase activities. Data are expressed as relative activities to those in pGL4.10 transfected cells (= 100) for each condition (pCI-neo, bCAR or bPXR co-transfection). Data are the mean ± SD (n = 3 or 4) and representative of one assay.