Figure 1.

SIRT1 deacetylates PGC-1α in skeletal muscle cells. (A) Fasting-induced PGC-1α deacetylation in skeletal muscle. Mice were either fed or fasted for 16 h and skeletal muscle was used to immunoprecipitate PGC-1α and Western blot was performed to detect PGC-1α levels and acetylation. (B) Nicotinamide and GCN5 induce PGC-1α acetylation. C₂C₁₂ myotubes were treated with 5 mM nicotinamide for 12 h and/or infected with the indicated adenoviruses for 48 h. After treatment, cells were harvested and protein cell extracts were used for PGC-1α immunoprecipitation and Western blot analysis using the specified antibodies. (C) PGC-1α is constitutively acetylated in SIRT1−/− MEFs. MEFs were treated with nicotinamide and/or infected with adenoviruses encoding PGC-1α as described in (B). (D) SIRT1 rescues PGC-1α deacetylation in SIRT1−/− MEFs. Adenoviruses expressing PGC-1α and SIRT1 were infected in MEFs as described in (B). (E) SIRT1 is bound to PGC-1α-targeted gene promoters. C₂C₁₂ myotubes were infected with adenoviruses encoding either GFP or PGC-1α. Forty-eight hours after infection, cells were harvested and ChIP analysis using SIRT1 antibody was performed as described in Materials and methods. Values in (E) represent the mean of two experiments performed in triplicate. Error bars represent s.e.m. Statistical analyses were performed using Student's t-test. ^*P<0.05 and ^**P<0.005.