FIGURE 6.

SIRT1 represses transcription of the PEPCK-C gene in HepG2 cells. Panel A, mouse SIRT1 was overexpressed in HepG2 cells in the absence (open bar) or presence of PKAc (black bar). Transcription of the PEPCK-C gene promoter was determined using a luciferase reporter assay. Panel B, RNAi knock-down of SIRT1 attenuated IsoNAM-induced transcriptional repression of PEPCK-C. HepG2 cells were co-transfected with p2000-Luc and no RNAi, control RNAi, or Sirt1 RNAi, and then treated with water (open bar) or 5 mm IsoNAM (black bar). Luciferase activity was measured 24 h later. The insert is a Western blot of SIRT1 in the lysates of the transfected cells. The luciferase activities were expressed as the mean ± S.E. from triplicate measurements.