FIGURE 3.

Effects of SIRT1 on PGC-1α gene promoter activity. C2C12 cells were transfected with a luciferase reporter construct driven by 2 kb of the mouse PGC-1α promoter region (PGC-1α -Luc). Data show the -fold induction of luciferase activity with respect to basal promoter values, and represent the means ± S.E. from at least three independent experiments performed in triplicate. a, cells were co-transfected with an expression vector for SIRT1 and treated with 50 μm resveratrol (RSV) or 10 mm NAM for 24 h, as indicated. Statistically significant differences (p < 0.05) due to drugs with respect to basal promoter values are denoted by the asterisk, and those due to the effects of SIRT1 are denoted by #. b, cells were co-transfected with expression vectors for PPARβ/δ, Foxo1, MEF2A, MEF2C, MEF2D, or MyoD, as indicated, as well as an expression vector for SIRT1 or the mutant form, SIRT1-H363Y. Cells transfected with PPARβ/δ were also treated with the specific agonist, 10 μm GW501516. Data show the -fold induction of luciferase activity with respect to basal promoter values, and represent the means ± S.E. from at least three independent experiments performed in triplicate. Statistically significant differences (p < 0.05) for each transfection condition with respect to basal promoter values are denoted by an asterisk, and those due to the effects of SIRT1 in the absence or presence of a given expression vector are denoted by #.