Fig. 1.
Pax7 deletion results in cell-cycle arrest and precocious differentiation. (A) Infection of Pax7fl/fl myoblasts with an adenovirus encoding the Cre gene leads to depletion of Pax7 expression and loss of Myf5 protein expression. (B) Infection of Pax7fl/fl myoblasts with an adenovirus encoding the Cre gene leads to depletion of Pax7 expression. Pax7 immunostaining is depicted in green. Nuclei are counterstained with DAPI. (Scale bar: 100 µm.) (C) Ad-Cre-mediated Pax7 deletion results in growth arrest in primary myoblasts, relative to control (Ad-GFP) myoblasts; n = 3, **P < 0.01. (D) The siRNA-mediated depletion of Pax7 expression in satellite cells leads to reduced numbers of satellite cells (marked by M-Cadherin staining in green) after 72 h of culture. Nuclei are counterstained with DAPI. (Scale bar: 100 µm.) (E) Following depletion of Pax7 in satellite cells on single myofibers, the number of satellite cells per fiber is significantly reduced; n = 4, ***P < 0.001. (F) Numbers of clusters (three or more satellite cells on a fiber attached to each other) are reduced following treatment with Pax7 siRNA compared with scrambled control; n = 4, ***P < 0.01. (G) Increase in the number of single satellite cells on myofibers following 72 h in culture and treatment with Pax7siRNA; n = 4, ***P < 0.01. (H) Numbers of myogenin-positive satellite cells increase after 72 h in culture following depletion of Pax7 expression with Pax7 siRNA; n = 4, ***P < 0.01.