Fig. 5

PXR activates MRP3 transcription by directly binding to its promoter. a Ectopic expression of PXR significantly enhances the endogenous expression of MRP3. PXR and MRP3 expressions were examined by RT-PCR and WB, and β-actin was used as an internal control. b Different regions of the MRP3 promoter were cloned into a luciferase reporter construct. c, d PXR targets MRP3 directly, and the key PXR binding region is located between -884 to -620bp of the MRP3 promoter as determined by luciferase reporter assays. The results were normalized to internal controls from three experiments. e ChIP-PCR was performed to identify MRP3 as a PXR target. Jaspar and ConSite predicted the PXR binding sites as located between -796 to -782bp of the MRP3 promoter. f The key PXR binding region is located between -884 to -754bp of the MRP3 promoter determined by luciferase reporter assays. The results were normalized to internal controls from three experiments. **P < 0.01. g The effects of PXR on wild-type and mutated/deleted MRP3 promoter (between -796 to -782bp) activity. Error bars indicate s.d. (n = 3), *, mutated sites; -, deleted sites. **P < 0.01