Abstract: Objective To detect the regulation of PGC-1α and ERRα on mouse SHP transcription in human hepatoma HepG2 cells, and to determine the cis-element involved in the regulation of ERRα on SHP promoter. Methods Transient transfection with ERRα and/or PGC-1α in HepG2 and human embryonic kiney 293A cells, then dual-luciferase reporter assay was performed to investigate fold activity of mouse SHP promoter reporter when overexpressing ERRα and PGC-1α. Reconstructing SHP promoter reporters including a series of 5′-deletions and cis-element mutations, dual-luciferase reporter assay was performed to screen ERRα binding sites in HepG2 cells. Results Coexpression of ERRα and PGC-1α stimulates the transcription of SHP in HepG2 and 293A cells. Five potential ERRα binding sites were identified by analyzing the sequence of SHP promoter. In the dual-luciferase reporter assay with 5′-deletions of promoter, three of five potential elements were demonstrated to be concerned with transcriptional regulation of ERRα. Furthermore, it was demonstrated that two sites of them involve in regulating SHP transcription by ERRα and PGC-1α using mutational promoter luciferase reporter assay, the other one may participate in the basal level transcription of SHP. Conclusion ERRα is a novel pathway that regulates SHP gene transcription in HepG2 cells besides FXR and ERRγ, only when the coactivator PGC-1α is in presence.

Key words: PGC-1α, ERRα, SHP, Transcriptional regulation