FIGURE 5.

ADAM10 is critically involved in the maintenance of quiescence in SCs mediated by Notch signaling. A, outline of the schedule for tamoxifen treatment and myotube culture. 8–12-Week-old Ctrl and Adam10^Pax7 mice were treated with tamoxifen for five consecutive days and then sacrificed (SAC) on day 7 (D7). Myofibers were harvested and incubated in the presence of 4-OHT for 4 days and analyzed on day 11 (D11). B, percentages of PAX7⁻/MYOD1⁺, PAX7⁺/MYOD1⁺, and PAX7⁺/MYOD1⁻ cells harvested from the myofibers of Ctrl and Adam10^Pax7 mice. n = 3 mice per genotype. *, p < 0.05. NS = not significant. C, immunostaining for N1ICD in SCs isolated from the myofibers of WT^Pax7-EGFP and Adam10^Pax7-EGFP mice. Cells positive for both EGFP and N1ICD (arrowheads) represent quiescent SCs, whereas cells positive for EGFP but negative for N1ICD represent activated or differentiated SCs. D, percentage of N1ICD⁺/EGFP⁺ cells harvested from the myofibers of WT^Pax7-EGFP and Adam10^Pax7-EGFP mice. n = 4 mice per genotype. **, p < 0.005. E and F, C2C12 cells transfected with control siRNA or siRNA against Adam10 were incubated on recombinant soluble DLL4 (sDDL4)-coated wells for 4 days. The formation of myotubes and the expression levels of Myog transcripts were evaluated by microscopy (E) and quantitative PCR (F), respectively. Bar, 100 μm. n = 3. **, p < 0.005. G, efficacy of the gene silencing was confirmed by quantitative PCR (left panel) and Western blot (right panel, arrowheads). n = 3. **, p < 0.005.