Figure 4. ERRα is required for the PGC-1α induction of Sirt3 expression.

A, The full-length wild-type Sirt3 promoter fused to luciferase reporter gene (Luc-2036) was cotransfected into HepG2 cells with pcDNA3.1 (control) or PGC-1α in the presence of shRNA against ERRα or luciferase (control). Two days later, cells were harvested and RLA analyzed. B, Knockdown of ERRα reduced the induction of Sirt3 mRNA level by PGC-1α. C₂C₁₂ myotubes were infected with adenoviruses expressing GFP or PGC-1α in the presence of Ad-siControl or Ad-siERRα. Total RNA was isolated 48 h later. Sirt3 mRNA level was determined by qPCR, normalized to β-actin, and expressed relative to control cells infected with Ad-GFP and Ad-siControl. All values represent at least three independent transfections, each conducted in triplicate. *, P<0.05.