Figure 1

Bmp7 and Noggin regulate terminal differentiation of C2C12 cells in opposite ways. C2C12 cells were treated in control medium (A,D,J) or supplemented with Bmp7 (B,E,K) or Noggin (C,F,L) and analyzed for terminal myogenic differentiation (MHC expression) (A-C), osteoblast differentiation (alkaline phosphatase activity) (D-F), BrdU incorporation (I) and apoptosis (J-L). (A-C) terminally differentiated, MHC expressing myoblasts/myotubes can be detected in control cultures (A). Bmp7 treatment inhibits myogenic differentiation (B), whereas Noggin treatment leads to enhanced myotube formation (C). DAPI was used to counterstain nuclei (100× magnification). (D-F) C2C12 cells express alkaline phosphatase upon Bmp7 treatment (E) but not in untreated (D) or Noggin-treated cultures (F) (50× magnification). (G) Statistical analysis using the generalized Wilcoxon test demonstrates significantly reduced numbers of MHC-positive cells after Bmp7 treatment and increased numbers after Noggin treatment (n = 6, 2 individual experiments in triplicates; *p < 0.005). Cell number (H) and BrdU incorporation (I) are upregulated after Bmp7 treatment (n = 6, 2 individual experiments in triplicates *p < 0.005; Wilcoxon test). (J-L) the apoptotic marker cleaved Caspase3 is absent after Bmp7 treatment (K) while apoptosis can be detected in control (J) and Noggin-treated cultures (L) (200× magnification).