Abstract: Objective we're trying to determine the cis-element in the regulation of rat ALAS-1 promoter by PGC-1β. Methods Transient transfection with PGC-1β was done in Hep G2, then dual-luciferase reporter assay was performed to investigate fold activity of rat ALAS-1 promoter when over-expressing PGC-1β. Reconstructing ALAS-1 promoter reporters including a series of 5'-deletions and cis-element mutations, dual-luciferase reporter assay was performed to assay NRF-1 binding sites in rat ALAS-1 promoter. We construct adenoviral PGC-1β and adenoviral siRNA of NRF1 and isolate rat primary hepatocytes and assay the effects of PGC-1β on the rat ALAS-1 transcription. Results Overexpression of PGC-1β stimulates the transcription of ALAS-1 in Hep G2 cells, while over-expressing NRF-1 alone had no stimulation. We constructed NRF-1 binding site mutated ALAS-1 promoter, the promoter activity was obviously diminished by overexpression of PGC-1β. PGC-1β promotes the transcription of ALAS-1 in the rat primary hepatocytes. When we use the siRNA to interfere the expression of NRF-1, the stimulating effect of PGC-1β on the ALAS-1 was attenuated. Conclusion PGC-1β promoting the transcription of ALAS-1 is mainly by NRF-1 in Hep G2 cells and rat primary hepatocytes.

Key words: PGC-1β, NRF-1, ALAS-1