Therapeutic induction of dytrophin-positive revertant fibres in the mdx mouse

Funded Activity Summary

Revertant fibres are low-abundance, dystrophin-positive fibres found in muscle of DMD patients and animal models. These fibres appear to have a selective advantage over dystrophin negative fibres, as they accumulate with age. Characterisation of dystrophin mRNA has identified in-frame transcripts missing multiple exons, which either exclude a nonsense mutation or restore the reading frame around a deletion. We have designed antisense oligonucleotides (AOs) to bind regions flanking the exon containing the dystrophin mutation in the mdx mouse. The AOs interfere with processing of the pre-mRNA to exclude the mutation and allow a slightly shortened dystrophin to be synthesised. The use of AOs to modify RNA processing allows the gene to function under the control of natural regulatory elements. We have shown that AOs can induce dystrophin expression and improve strength in dystrophic (mdx) mouse hindlimb muscles. We aim to improve upon these results by using AOs to block splice sites flanking consecutive exons, in order to induce dystrophin which mimics that of revertant fibres. As most revertant transcripts are missing multiple exons, we believe that the functional capacity of AO-induced dystrophin can be improved upon by removing multiple exons. An mdx mouse skeletal muscle cell line is used for evaluation AOs. However, in order to determine the efficacy of the induced dystrophin in cardiac and skeletal muscle, experiments must be performed on mice. Previous work, in vitro and in muscles of mdx mice have validated this approach. Combinations of AOs which show promise will be delivered by a) intravascular injection b) intraperitoneal injection in mdx mice. The efficacy of the treatment will be assessed by both continual and end point analysis, which includes physiological, clinical, molecular and histological testing. Particular attention will be directed to the well-being of the mice and any adverse side effects which may occur.

Funded Activity Details

Start Date: 01-01-2004

End Date: 01-01-2006

Funding Scheme: NHMRC Project Grants

Funding Amount: $454,825.00

Funder: National Health and Medical Research Council

Research Topics

ANZSRC Field of Research (FoR)

Gene and Molecular Therapy

ANZSRC Socio-Economic Objective (SEO)

There are no SEO codes available for this funding activity

Other Keywords

Duchenne muscular dystrophy | alternative splicing | antisense oligonucleotide | antisense oligonucleotide treatment | dystrophin | gene expression | genetic therapy | induced exon skipping | targeted therapy

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