Figure 6.

MBNL1 overexpression corrects a DM skeletal muscle phenotype. (A) Schematic diagram of MBNL1-OE and HSA^LR cross. (B) RNA foci in skeletal muscle from HSA^LR and HSA^LR;MBNL1-OE mice detected with a Cy3 conjugated CAG₈ oligonucleotide probe. No foci were detected in wild-type FVB mice. (C) RT-PCR splicing assays of FVB wild-type (WT), singly transgenic HSA^LR (HSA) and doubly transgenic HSA^LR;MBNL1-OE mice (D). (D) EMG trace from an HSA^LR gastrocnemius muscle showing a single needle insertion resulting in a ∼2s myotonic discharge and trace from an HSA^LR;MBNL1-OE doubly transgenic mouse gastrocnemius showing two normal needle insertion responses without electrical myotonia. (E) Hematoxylin and eosin staining of quadriceps muscle from 12-month FVB wild-type, singly transgenic HSA^LR and doubly transgenic HSA^LR;MBNL1-OE mice. Ringed fibers (asterisk) and multiple central nuclei (arrow) shown in the HSA^LR mouse. (F) Quantitation of centrally nucleated fibers in FVB wild-type, HSA^LR and HSA^LR;MBNL1-OE mice. Averages are shown ±SEM.