FIG 3.

Correction of GSK3β reduces the levels of the mutant CUG repeats in HSA^LR mice. (A) Design of the treatment of HSA^LR mice with TG. The grip strength was measured before the course of the treatment and the day after each treatment as an outcome of the efficacy of the correction of GSK3β in HSA^LR muscle. (B) Northern blot analysis of skeletal muscle mix from matched WT and HSA^LR mice treated with the vehicle (Veh) or TG using (CAG)₁₀ probe. GAPDH was used as a loading control. (C) The quantification of the mutant CUG RNA in skeletal muscle of HSA^LR mice treated with TG, shown in panel B, was performed as described in Materials and Methods. (D) Representative images of FISH analysis of skeletal muscle of HSA^LR mice, treated with the vehicle or TG, using CAG probe. Nuclei were stained with DAPI. The scale bar is 100 μm. (E) The percentage of nuclear CUG foci in gastroc from 5-month-old HSA^LR mice untreated and treated with TG (2 doses, 0.1 μg/g) determined by FISH assay. (F) Western blot analysis of GSK3β and the downstream myogenic CUGBP1 targets, RBM45 and DCX, in gastroc from 5-month-old WT mice and HSA^LR mice untreated and treated with TG (2 doses, 0.1 μg/g). β-Actin was a control for protein loading. (G) Correction of misregulated splicing of Serca1 and Cypher in HSA^LR mice treated with TG. Serca1 was analyzed in TA muscle from HSA^LR mice treated i.p. with two doses of TG (0.1 μg/g). Cypher was analyzed in gastroc of HSA^LR mice treated four times with oral TG (0.1 μg/g). (H and I) Quantification of the signals, shown in panel G, based on three repeats, was performed as described in Materials and Methods. *, P < 0.05; ****, P < 0.0001.