Figure 6. Reducing SIRT1 activity increases, and increasing SIRT1 expression decreases, mitochondrial enzymes in C₂C₁₂ myotubes and rat skeletal muscle.

(A) Suppression of SIRT1 activity with dominant-negative SIRT1 H355A in C₂C₁₂ myotubes increases mitochondrial proteins. Values are means ± SE for 6–10 experiments per group. p<0.5 versus control. (B) Suppression of SIRT1 activity by expression of dominant-negative SIRT1 H355A in rat triceps muscle by electroporation resulted in increases in mitochondrial proteins. Values are means ± SE for 5–7 muscles per group. *p<0.05 versus control. (C) Knockdown of SIRT1 with a SIRT1 shRNA in C₂C₁₂ myotubes resulted in increases in mitochondrial proteins. Values are means ± SE for 6–8 experiments per group. *p<0.05 versus control. (D) Overexpression of wild-type (WT) SIRT1 in C₂C₁₂ myotubes resulted in decreased cytochrome c protein expression and inhibited the resveratrol (RSV)-induced increase in cytochrome c. Values are means ± SE for 6 experiments. *p<0.05 versus control. ^# p<0.05 versus other groups. (E) Overexpression of wild-type (WT) SIRT1 in rat triceps muscle by electroporation resulted in decreased expression of mitochondrial proteins. Values are means ± SE for 7–8 muscles per group. *p<0.05 versus empty vector.