Figure 4.

Rpt3 Inactivation Depletes the Satellite Cell Pool

(A) Time course of tamoxifen (Tmx) treatment and tissue harvesting. Con indicates Rpt3^f/f mice and scKO indicates satellite cell-specific Rpt3 knockout mice (Pax7^CreERT2/+; Rpt3^f/f).

(B) Immunostaining for PAX7 (green) and DAPI (blue) in the extensor digitorum longus (EDL) single fiber 5 days after Tmx induction. Arrows indicate satellite cells. Scale bar, 50 μm.

(C) Number of satellite cells per fresh EDL myofiber from Con and scKO mice 0–15 days after Tmx treatment. Data represent mean ± SEM (t test: ^∗p < 0.05, ^∗∗∗p < 0.001; day 0, n = 5; day 3, n = 4; day 5, n = 5; day 10, n = 5; day 15, n = 4 per group; more than 15 myofibers per animal).

(D) Immunostaining for PAX7 (green), laminin (red), and DAPI (blue) in tibialis anterior (TA) muscle cryosections 5 days after Tmx treatment. Arrows indicate satellite cells. Scale bar, 20 μm.

(E) Average number of satellite cells per 100 fibers. Data represent mean ± SEM (t test: ^∗∗p < 0.01; day 5, n = 4; day 15, n = 5 for each group).

(F) Immunostaining for M-cadherin (green), Laminin2α (red), and DAPI (blue) in intact TA muscle cryosections from scKO mice. Arrows indicate satellite cells. Scale bar, 50 μm.

(G) Average number of M-cadherin+ cells per 100 fibers. Data represent means ± SD (t test: ^∗∗∗p < 0.001; n = 3 per group).

(H) Fluorescence-activated cell sorting profiles of mononuclear cells derived from Con and scKO mice 2 and 15 days after Tmx treatment. The gated profiles show satellite cell fractions (SM/C-2.6 + CD31− CD45− Sca1−) from Con and scKO mice.

(I) Relative satellite cell fractions from Con and scKO mice. Data represent mean ± SEM (t test: ^∗∗∗p < 0.001; day 2, n = 4; day 15, n = 4 per group). SC, satellite cell.

See also Figures S4 and S5.