Fig 7. Loss of RGS12 leads to a transient impairment in muscle repair.

A, Representative cross-sections of tibialis anterior (TA) muscle from indicated mice, labeled 8 days after cardiotoxin (CTX) injection with wheat-germ agglutinin (WGA; green) and nuclear DNA (blue). B, Representative micrographs of H&E-stained TA muscle 8 days after CTX-induced injury. C, Relative frequency distribution of the cross-sectional area (CSA) of regenerating (i.e., centrally-nucleated) muscle fibers 8 days after CTX injection as measured by EVOS FL Auto software based on WGA staining (>800 fibers/mouse). Differences between Rgs12^fl/fl; Pax7::Cre mice (n = 5) and wild-type Pax7::Cre mice (n = 6) were evaluated using a two-way ANOVA with Sidak’s post hoc test. ****, p<0.0001; *, p<0.05. Inset: The mean CSA of centrally nucleated fibers was shifted towards smaller area in Rgs12^fl/fl; Pax7::Cre mice vs wild-type Pax7::Cre mice as assessed by a Student’s t-test; *, p<0.05. Data are presented as mean ± SEM. D, Representative cross-sections of TA muscle from indicated mice, labeled 24 days after CTX injection with WGA (green) and nuclear DNA (blue). E, CSA of regenerated myofibers in TA muscle of Rgs12^fl/fl; Pax7::Cre mice (n = 5) and wild-type Pax7::Cre mice (n = 5) 24 days after CTX injury were measured by EVOS FL Auto software based on WGA staining. No differences in fiber CSA were found between genotypes. Inset: The mean CSA of centrally nucleated fibers was not different in Rgs12^fl/fl; Pax7::Cre mice (n = 5) and wild-type Pax7::Cre mice (n = 5) as assessed by a Student’s t-test. Data are presented as mean ± SEM. F. The maximal tetanic isometric plantar flexor tension of Rgs12^fl/fl; Pax7::Cre mice (n = 5) and wild-type Pax7::Cre mice (n = 5) was obtained in both CTX and PBS treated legs at 14 and 28 days following injection. 14 days post-injection Rgs12^fl/fl; Pax7::Cre mice trended towards more impairment in the CTX injected leg relative to wild-type mice, as evaluated by a Student’s t-test (p = 0.06). By 28 days post-CTX injection, both genotypes had recovered to an equivalent level relative to their PBS-injected leg. Data are presented as mean ± SEM.