TEAD1 mediates miR-133a and TH action in myofiber specification. (A and B) C2C12 myotubes were cotransfected with miR-133a mimics and/or TEAD1 with or without 3′ UTR. 48 h after transfection, immunostaining was performed. Bars, 200 µm. (C) Quantitative values were determined in four random fields for each group. (D) qRT-PCR analysis of the expression of TEAD1 and MyHC isoforms in C2C12 myotubes transfected with TEAD1 in the presence of T3. (E) qRT-PCR analysis of the expression of TEAD1 and MyHC isoforms in SOL muscles of MMI-treated mice, MMI-treated mice with T3 treatment for 5 d, and MMI-treated mice with electrotransfer of TEAD1 and T3 treatment for 5 d (n = 3). (F) Schematic representation of miR-133a–mediated TH function in muscle fiber type determination. Means ± SD (error bars) are shown. *, P < 0.05; **, P < 0.01.