Reengineering a transmembrane protein to treat muscular dystrophy using exon skipping

J Clin Invest. 2015 Nov 2;125(11):4186-95. doi: 10.1172/JCI82768. Epub 2015 Oct 12.

Abstract

Exon skipping uses antisense oligonucleotides as a treatment for genetic diseases. The antisense oligonucleotides used for exon skipping are designed to bypass premature stop codons in the target RNA and restore reading frame disruption. Exon skipping is currently being tested in humans with dystrophin gene mutations who have Duchenne muscular dystrophy. For Duchenne muscular dystrophy, the rationale for exon skipping derived from observations in patients with naturally occurring dystrophin gene mutations that generated internally deleted but partially functional dystrophin proteins. We have now expanded the potential for exon skipping by testing whether an internal, in-frame truncation of a transmembrane protein γ-sarcoglycan is functional. We generated an internally truncated γ-sarcoglycan protein that we have termed Mini-Gamma by deleting a large portion of the extracellular domain. Mini-Gamma provided functional and pathological benefits to correct the loss of γ-sarcoglycan in a Drosophila model, in heterologous cell expression studies, and in transgenic mice lacking γ-sarcoglycan. We generated a cellular model of human muscle disease and showed that multiple exon skipping could be induced in RNA that encodes a mutant human γ-sarcoglycan. Since Mini-Gamma represents removal of 4 of the 7 coding exons in γ-sarcoglycan, this approach provides a viable strategy to treat the majority of patients with γ-sarcoglycan gene mutations.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Codon, Nonsense / genetics
  • Diaphragm / metabolism
  • Diaphragm / pathology
  • Drosophila Proteins / deficiency
  • Drosophila Proteins / genetics
  • Drosophila melanogaster / genetics
  • Dystrophin-Associated Protein Complex / chemistry*
  • Exons
  • Fibrosis
  • Genetic Therapy*
  • HEK293 Cells
  • Humans
  • Mice
  • Mice, Transgenic
  • Muscle, Skeletal / metabolism
  • Muscle, Skeletal / pathology
  • Muscular Dystrophies, Limb-Girdle / genetics
  • Muscular Dystrophies, Limb-Girdle / therapy*
  • Muscular Dystrophy, Animal / genetics
  • Muscular Dystrophy, Animal / pathology
  • Muscular Dystrophy, Animal / therapy
  • Mutation
  • Myocardium / metabolism
  • Myocardium / pathology
  • Oligonucleotides, Antisense / pharmacology
  • Oligonucleotides, Antisense / therapeutic use*
  • Protein Engineering*
  • Protein Interaction Mapping
  • Protein Structure, Tertiary
  • RNA, Messenger / chemistry
  • RNA, Messenger / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sarcoglycans / biosynthesis
  • Sarcoglycans / chemistry
  • Sarcoglycans / deficiency
  • Sarcoglycans / genetics*
  • Sarcolemma / metabolism
  • Sequence Deletion

Substances

  • Codon, Nonsense
  • Drosophila Proteins
  • Dystrophin-Associated Protein Complex
  • Oligonucleotides, Antisense
  • RNA, Messenger
  • Recombinant Fusion Proteins
  • Sarcoglycans
  • Scgdelta protein, Drosophila