Deletion of suppressor of cytokine signaling 3 (SOCS3) in muscle stem cells does not alter muscle regeneration in mice after injury
Fig 4
SOCS3 deletion in muscle stem cells does not impair regenerative capacity after sequential myotoxic injuries.
Tamoxifen-treated control (SOCS3fl/fl Pax7-CreER-) and SOCS3 MscKO (SOCS3fl/fl Pax7-CreER+) mice received a single 40 μL injection of notexin (10 μg/ml) into the right TA muscle and were left to recover for 28 days. On day 28 post-injury, all mice received a second single 40 μL injection of notexin (10 μg/ml) into the right TA muscle and were killed for analysis 14 days after the second injury (A). Muscle mass relative to the uninjured left TA muscle (B) and muscle fiber cross-sectional area (CSA; C), maximum isometric force (D), and specific (normalized) force (E) were measured at D14 post the second injury (D56). Data are expressed as mean ± SEM. Statistical analysis was performed using a two-sided Student’s t-test. n = 4–6 mice/time-point/genotype. Force production during a 4-minute fatiguing protocol comparing D56 injured right TA muscles from control and SOCS3 MscKO mice (F). Data are expressed as mean ± SEM. Statistical analysis was performed using a repeated measures two-way ANOVA with a Bonferroni’s post-hoc multiple comparisons test to determine effects of genotype and time. n = 4–6 mice/time-point/genotype. Representative CD68 (left) and DAPI (right) immunostained sections of TA muscle from control and SOCS3 MscKO mice at D56 post-injury. The proportion of CD68 positive nuclei was determined using Axiovision software (G). Representative Pax7 (left) and DAPI (right) immunostained sections of TA muscle from control and SOCS3 MscKO mice at D56 post-injury. The number of Pax7 positive nuclei (as indicated by arrows) was counted per field of view (H). Representative black and white laminin and DAPI immunostained sections of TA muscle from control and SOCS3 MscKO mice at D56 post-injury. Muscle fibers containing 1, 2, or 3+ -located nuclei were counted per field of view (I). Scale bar = 100 μm. Data are expressed as mean ± SEM. Statistical analysis was performed using an unpaired Student’s t-test. n = 6 mice/time-point/genotype. **P < 0.01 compared to control.