Figure 2. The demethylase activity of UTX plays a critical role in SC-mediated muscle repair.

(A and B) Analysis of muscle regeneration 7 days after CTX treatment in mice treated with daily i.p. injections of GSK-J4 (A) — an inhibitor of the demethylase activity of UTX and JMJD3 — and UTX^KI mice (B). The experimental approach is schematically represented where CTX injections are indicated by red arrows, while GSK-J4 injections are shown by pink arrows. Cross sections of TA muscles were visualized after H&E staining to evaluate muscle integrity in noninjured (normal) and CTX-injected (regenerating) muscle at 7 days after tissue injury. Necrotic tissue and infiltrating immune cells are indicated by red arrows. Each image panel is visualized under ×20 magnification and represents a total area of 90,000 μm². Myofiber calibers within the TA muscle were calculated and plotted for each condition (n > 500 total fibers per condition). Each dot represents the area of a single myofiber; the horizontal bar correspond to the mean within the 95% confidence interval (box). Statistical significance was determined using an ANOVA test where *P < 0.05. Measurements have been performed on a minimum of 9 mice taken from 3 independent experiments.