Figure 3

Bmp7 maintains Pax7 expression in satellite cells. Satellite cells were cultured on myofibers for 18 hours under standard (A-D) or serum free (SR) (E-L) conditions. (A-D) p-Smad colocalize with Pax7 in standard medium. (I-L) In serum free cultures Bmp7 treatment induces p-Smad phosphorylation in Pax7-positive cells. In untreated cultures p-Smad cannot be detected (E-H). Absence of p-Smad causes a severe downregulation of Pax7. Nuclei were counterstained with DAPI. Magnification is 400×. (M) Analysis of the mean fluorescent intensity of the Pax7 signal in satellite cells revealed a downregulation to 50% in the absence of Bmp7 treatment (n = 30 satellite cells per treatment from 3 individual experiments, * p = 0.005, Wilcoxon test). Magnification is 400×. SR = serum replacement.