Figure 7: The miR-431 transgene reduces the dystrophic phenotype in mdx mice.

miR-431::mdx mice were generated by crossing miR-431 TG mice with mdx mice. Values are means±s.e.m. of experiments with five to eight mice at 5 months of age.*P<0.05, **P<0.01, ***P<0.001. NS, not significant. (a) Serum creatine kinase (CK) levels in C57BL/6 WT and mdx control or miR-431::mdx mice. (b) Evans blue dye uptake in TA muscle. Scale bar, 50 μm. (c) Percentage of Evans blue-positive fibre area in TA muscle of mdx and miR-431::mdx mice. (d) Running time to exhaustion on the downhill treadmill test. (e) Maximal twitch force induced by electrical stimulation in vitro to elicit tetanic contractions in EDL muscle from C57BL/6, mdx and miR-431::mdx mice. (f) Peak twitch force induced in EDL muscle by electrical stimulation in vitro. (g) Pax7 (red) and MyoD (green) double staining on sections of TA muscles from mdx and mdx::miR-431 mice. Scale bar, 100 μm. (h) Numbers of Pax7⁺/MyoD⁺, Pax7^–/MyoD⁺ and Pax7⁺/MyoD^– cells in the stained sections in g. (i,j) Expression of dystrophin (i) and utrophin (j) in TA muscle of mdx and mdx::miR-431 mice, analysed using real-time RT–PCR. GAPDH was the internal control.