Fig. 7.

Supplementation of FGF rescues the effect of loss of MyHC-embryonic on myogenesis. (A-B‴) Immunofluorescence labeling for MyHC (red), phalloidin (green) and DAPI (blue) on C2C12 cells at day 5, where Myh3 has been knocked down, treated with control media without FGF (A-A‴) or with FGF-supplemented media (B-B‴); A‴ and B‴ are magnifications from A″ and B″, respectively. (C,D) Quantification of reserve cell number per unit area (mm²) (C) and fusion index (D) from Myh3 siRNA-treated C2C12 cells at day 5, treated with FGF-supplemented media compared with the control. (E-G) Western blots for MyoD, myogenin and β-actin on Myh3 siRNA-treated C2C12 cells at days 3, 5 and 7 of differentiation, grown in the presence or absence of FGF (E), and densitometric quantification (F-G). The symbols, ‘−’ and ‘+’ denote absence or presence of FGF in the media (E). (H,I) Six-week old Myh3^Δ/Δ mice exhibit scoliosis (I), compared with control Myh3^Δ/+ animals (H). (J) Model summarizing the cell-autonomous and non-cell-autonomous roles of MyHC-embryonic during embryonic, fetal and neonatal myogenesis, where it regulates FGF levels, which control the rate of myogenic differentiation. Data are mean±s.e.m. of a minimum of three independent experiments. Scale bars: 100 μm (B″); 33 μm (B‴).