Identification of novel antisense-mediated exon skipping targets in DYSF for therapeutic treatment of dysferlinopathy

Dysferlinopathy is a progressive myopathy caused by mutations in the dysferlin (DYSF) gene.
Dysferlin protein plays a major role in plasma membrane resealing. Some patients with DYSF
deletion mutations exhibit mild symptoms, suggesting some regions of DYSF can be removed
without significantly impacting protein function. Antisense-mediated exon skipping therapy uses
synthetic molecules called antisense oligonucleotides to modulate splicing, allowing exons
harboring or near genetic mutations to be removed and the open reading frame corrected.
Previous studies have focused on DYSF exon 32 skipping as a potential therapeutic approach,
based on the association of a mild phenotype with the in-frame deletion of exon 32. To date, no
other DYSF exon skipping targets have been identified and the relationship between DYSF exon
deletion pattern and protein function remains largely uncharacterized. In this study, we utilized a
membrane wounding assay to evaluate the ability of plasmid constructs carrying mutant DYSF,
as well as antisense oligonucleotides, to rescue membrane resealing in patient cells. We report
that multi-exon skipping of DYSF exons 26-27 and 28-29 rescues plasma membrane resealing.
Successful translation of these findings into the development of clinical antisense drugs would
establish new therapeutic approaches that would be applicable to ~5-7% (exons 26-27 skipping)
and ~8% (exons 28-29 skipping) of dysferlinopathy patients worldwide.