In-frame dystrophin following exon 51-skipping improves muscle pathology and function in the exon 52-deficient mdx mouse

Mol Ther. 2010 Nov;18(11):1995-2005. doi: 10.1038/mt.2010.186. Epub 2010 Sep 7.


A promising therapeutic approach for Duchenne muscular dystrophy (DMD) is exon skipping using antisense oligonucleotides (AOs). In-frame deletions of the hinge 3 region of the dystrophin protein, which is encoded by exons 50 and 51, are predicted to cause a variety of phenotypes. Here, we performed functional analyses of muscle in the exon 52-deleted mdx (mdx52) mouse, to predict the function of in-frame dystrophin following exon 51-skipping, which leads to a protein lacking most of hinge 3. A series of AOs based on phosphorodiamidate morpholino oligomers was screened by intramuscular injection into mdx52 mice. The highest splicing efficiency was generated by a two-oligonucleotide cocktail targeting both the 5' and 3' splice sites of exon 51. After a dose-escalation study, we systemically delivered this cocktail into mdx52 mice seven times at weekly intervals. This induced 20-30% of wild-type (WT) dystrophin expression levels in all muscles, and was accompanied by amelioration of the dystrophic pathology and improvement of skeletal muscle function. Because the structure of the restored in-frame dystrophin resembles human dystrophin following exon 51-skipping, our results are encouraging for the ongoing clinical trials for DMD. Moreover, the therapeutic dose required can provide a suggestion of the theoretical equivalent dose for humans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biomarkers / metabolism
  • Blotting, Western
  • Creatine Kinase / blood
  • Dystrophin / physiology*
  • Exons / physiology*
  • Gene Expression Profiling
  • Genetic Therapy*
  • Immunoenzyme Techniques
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Inbred mdx
  • Muscle, Skeletal / metabolism*
  • Muscle, Skeletal / pathology*
  • Muscular Dystrophy, Duchenne / genetics
  • Muscular Dystrophy, Duchenne / pathology
  • Muscular Dystrophy, Duchenne / therapy*
  • Oligonucleotide Array Sequence Analysis
  • Oligonucleotides, Antisense / therapeutic use*
  • RNA Splicing*
  • RNA, Messenger / genetics
  • Reverse Transcriptase Polymerase Chain Reaction


  • Biomarkers
  • Dystrophin
  • Oligonucleotides, Antisense
  • RNA, Messenger
  • Creatine Kinase