FIGURE 5.

Effects of SIRT1 on a MyoD response-defective mutant form of the human PGC-1α promoter. C2C12 cells were transfected with a luciferase construct containing 49 bp of the proximal human PGC-1α promoter core region (hPGC-1α-LUC wt) or a version in which the two E boxes (which mediate MyoD responsiveness) have been mutated (hPGC-1α-LUC Mt3). Cells were co-transfected with expression vectors for SIRT1 and/or MyoD as indicated. The results are expressed as -fold induction of luciferase activity with respect to basal promoter values, and represent the means ± S.E. of at least three independent experiments performed in triplicate. Statistically significant differences are denoted by the asterisk (MyoD versus vector control, p < 0.01), # (SIRT1 versus control vector, p < 0.01), and † (wt versus Mt3, p < 0.005).