Fig. 1.

Wnt-3a or LiCl promote myoblast fusion during differentiation. C2C12 myoblasts were differentiated for a 72 h in control-CM or Wnt-3a-CM (each diluted 1/10 in DM), or DM in presence or absence of LiCl (10 mM), fixed and stained with May-Grunwald Giemsa to determine myoblast fusion and myotube formation or for 24 h to determine mRNA expression. Shown are representative pictures of >10 independent experiments at 40× and 100× magnification. From these pictures (b), myoblast fusion was quantified by determining nuclear distribution of 800–1,800 nuclei for each separate condition, which is expressed as the percent of nuclei residing in cells containing 1, 2, or >2 nuclei, reflecting mononucleated myoblasts (one nucleus), dividing or fusing myoblasts (two nuclei) or myotubes (>2 nuclei), respectively shown is representative data of three independent experiments. b Wnt-3a-CM was pre-incubated with an anti-Wnt-3a antibody, and cells were cultured for 120 h and myonuclear distribution was assessed. c Stratification of myonuclear content in myotubes of LiCl or Wnt-3a-treated cultures. d C2C12 myoblasts were differentiated for 24 h and RNA was extracted for assessment of proliferation-associated mRNA transcripts shown are (c, d) representative data of three independent experiments (n = 3 ± SEM), *p < 0.01, and NS non-significant