Human Molecular Genetics Advance Access originally published online on August 18, 2009
Human Molecular Genetics 2009 18(22):4405-4414; doi:10.1093/hmg/ddp395
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A fusion peptide directs enhanced systemic dystrophin exon skipping and functional restoration in dystrophin-deficient mdx mice
1 Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK, 2 Tianjin Research Centre of Basic Medical Science, Tianjin Medical University, Qixiangtai Road, Heping District, Tianjin 300070, China and 3 AVI Biopharma Inc., Corvallis, OR 97333, USA
* To whom correspondence should be addressed. Tel: +44 1865272419; Fax: +44 1865272420; Email: matthew.wood{at}dpag.ox.ac.uk
Received July 20, 2009; Accepted August 14, 2009
Duchenne muscular dystrophy (DMD) is caused by mutations in the DMD gene that abolish the synthesis of dystrophin protein. Antisense oligonucleotides (AOs) targeted to trigger excision of an exon bearing a mutant premature stop codon in the DMD transcript have been shown to skip the mutated exon and partially restore functional dystrophin protein in dystrophin-deficient mdx mice. To fully exploit the therapeutic potential of this method requires highly efficient systemic AO delivery to multiple muscle groups, to modify the disease process and restore muscle function. While systemic delivery of naked AOs in DMD animal models requires high doses and is of relatively poor efficiency, we and others have recently shown that short arginine-rich peptide-AO conjugates can dramatically improve in vivo DMD splice correction. Here we report for the first time that a chimeric fusion peptide (B-MSP-PMO) consisting of a muscle-targeting heptapeptide (MSP) fused to an arginine-rich cell-penetrating peptide (B-peptide) and conjugated to a morpholino oligomer (PMO) AO directs highly efficient systemic dystrophin splice correction in mdx mice. With very low systemic doses, we demonstrate that B-MSP-PMO restores high-level, uniform dystrophin protein expression in multiple peripheral muscle groups, yielding functional correction and improvement of the mdx dystrophic phenotype. Our data demonstrate proof-of-concept for this chimeric peptide approach in DMD splice correction therapy and is likely to have broad application.