Figure 7.

SMURF2 rescues skeletal muscle atrophy and drives a switch from fast-twitch to slow-twitch fibers via the TGF-β/SMAD pathway

(A and B) Relative SMURF2 mRNA (A) (n = 3) and protein (B) (n = 4) expression in gastrocnemius muscle with infection of SMURF2-expressing lentivirus (LV-SMURF2) or LV-NC. (C and D) H&E staining (C) (n = 4) and frequency distribution of CSA (D) (n = 4) of gastrocnemius muscle injected with the listed lentivirus. (E) Relative mRNA expression of the atrophy and autophagy-related genes in gastrocnemius muscle after infection with the indicated lentivirus (n = 4). (F and G) ATPase staining (F) (n = 4) and fiber type content (G) (n = 4) of gastrocnemius muscle infected with the indicated lentivirus. (H and I) Immunohistochemistry analysis of MYH1/MYH7 (H) (n = 4) and MYH1/MYH7 protein content (I) (n = 4) of gastrocnemius muscle injected with the indicated lentivirus. (J) Relative enzymes activity of LDH and SDH in gastrocnemius muscle infected with the listed lentivirus (n = 4). (K and M) Relative TGFB1 mRNA expression in gastrocnemius muscle infected with the indicated lentivirus (n = 4). (L and N) Protein expression levels of the TGF-β/SMAD pathway with infection of the indicated lentivirus (n = 3). Results are expressed as the mean ± SEM. Statistical significance of differences between means was assessed using independent sample t test. ∗p < 0.05, ∗∗p < 0.01.