Dataset: Dual Myostatin and Dystrophin Exon Skipping by Morpholino Nucleic Acid Oligomers Conjugated to a Cell-penetrating Peptide Is a Promising Therapeutic Strategy for the Treatment of Duchenne Muscular DystrophyAlberto Malerba, Jagjeet K Kang, Graham McClorey, Amer F Saleh, Linda Popplewell, Michael J Gait, Matthew Ja Wood, George Dickson
Article: Dual Myostatin and Dystrophin Exon Skipping by Morpholino Nucleic Acid Oligomers Conjugated to a Cell-penetrating Peptide Is a Promising Therapeutic Strategy for the Treatment of Duchenne Muscular Dystrophy.Alberto Malerba, Jagjeet K Kang, Graham McClorey, Amer F Saleh, Linda Popplewell, Michael J Gait, Matthew Ja Wood, George Dickson[show abstract] [hide abstract]
ABSTRACT: The knockdown of myostatin, a negative regulator of skeletal muscle mass may have important implications in disease conditions accompanied by muscle mass loss like cancer, HIV/AIDS, sarcopenia, muscle atrophy, and Duchenne muscular dystrophy (DMD). In DMD patients, where major muscle loss has occurred due to a lack of dystrophin, the therapeutic restoration of dystrophin expression alone in older patients may not be sufficient to restore the functionality of the muscles. We recently demonstrated that phosphorodiamidate morpholino oligomers (PMOs) can be used to re-direct myostatin splicing and promote the expression of an out-of-frame transcript so reducing the amount of the synthesized myostatin protein. Furthermore, the systemic administration of the same PMO conjugated to an octaguanidine moiety (Vivo-PMO) led to a significant increase in the mass of soleus muscle of treated mice. Here, we have further optimized the use of Vivo-PMO in normal mice and also tested the efficacy of the same PMO conjugated to an arginine-rich cell-penetrating peptide (B-PMO). Similar experiments conducted in mdx dystrophic mice showed that B-PMO targeting myostatin is able to significantly increase the tibialis anterior (TA) muscle weight and when coadministered with a B-PMO targeting the dystrophin exon 23, it does not have a detrimental interaction. This study confirms that myostatin knockdown by exon skipping is a potential therapeutic strategy to counteract muscle wasting conditions and dual myostatin and dystrophin skipping has potential as a therapy for DMD.Molecular Therapy - Nucleic Acids (2012) 1, e62; doi:10.1038/mtna.2012.54; published online 18 December 2012.Molecular therapy. Nucleic acids. 01/2012; 1:e62.
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ABSTRACT: Duchenne muscular dystrophy (DMD) is caused by mutations that disrupt the reading frame of the human DMD gene. Selective removal of exons flanking an out-of-frame DMD mutation can result in an in-frame mRNA transcript that may be translated into an internally deleted Becker muscular dystrophy-like functionally active dystrophin protein with therapeutic activity. Antisense oligonucleotides (AOs) can be designed to bind to complementary sequences in the targeted mRNA and modify pre-mRNA splicing to correct the reading frame of a mutated transcript. AO-induced exon skipping resulting in functional truncated dystrophin has been demonstrated in animal models of DMD both in vitro and in vivo, in DMD patient cells in vitro in culture, and in DMD muscle explants. The recent advances made in this field suggest that it is likely that AO-induced exon skipping will be the first gene therapy for DMD to reach the clinic. However, it should be noted that personalized molecular medicine may be necessary, since the various reading frame-disrupting mutations are spread across the DMD gene. The different deletions that cause DMD would require skipping of different exons, which would require the optimization and clinical trial workup of many specific AOs. This chapter describes the methodologies available for the optimization of AOs, in particular phosphorodiamidate morpholino oligomers, for the targeted skipping of specific exons on the DMD gene.Methods in molecular biology (Clifton, N.J.) 01/2012; 867:143-67.
Article: Long-term systemic administration of unconjugated morpholino oligomers for therapeutic expression of dystrophin by exon skipping in skeletal muscle: implications for cardiac muscle integrity.[show abstract] [hide abstract]
ABSTRACT: Duchenne muscular dystrophy (DMD) is a lethal X-linked inherited disease caused by mutations in the dystrophin gene and consequent lack of dystrophin in the skeletal, cardiac, and smooth musculature and in the nervous system. Patients die during their mid-twenties because of severe muscle loss and life-threatening respiratory and cardiac complications. The splicing modulation approach mediated by antisense oligonucleotides can restore the production of a partially functional quasi-dystrophin in skeletal muscles. We recently showed that a chronic, 12-month treatment with phosphorodiamidate morpholino oligomers efficiently restored dystrophin in widespread skeletal muscles and led to normal locomotor activity indistinguishable from that of dystrophin-expressing C57 mice. However, no detectable dystrophin expression was observed in the hearts of treated mice. In the present study, histological analyses show a more severe cardiac pathology compared with untreated animals in the face of enhanced locomotor behavior. This observation implies that the increase in locomotor activity of treated mdx mice may have a paradoxical detrimental effect on the dystrophic heart. In the context of skeletal muscle-centric therapies for DMD, our data suggest that particular vigilance should be instigated to monitor emergence of accelerated cardiac dysfunction.Nucleic acid therapeutics. 08/2011; 21(4):293-8.
Article: Delivery of AAV2/9-microdystrophin genes incorporating helix 1 of the coiled-coil motif in the C-terminal domain of dystrophin improves muscle pathology and restores the level of α1-syntrophin and α-dystrobrevin in skeletal muscles of mdx mice.Taeyoung Koo, Alberto Malerba, Takis Athanasopoulos, Capucine Trollet, Luisa Boldrin, Arnaud Ferry, Linda Popplewell, Helen Foster, Keith Foster, George Dickson[show abstract] [hide abstract]
ABSTRACT: Duchenne muscular dystrophy is a severe X-linked inherited muscle wasting disorder caused by mutations in the dystrophin gene. Adeno-associated virus (AAV) vectors have been extensively used to deliver genes efficiently for dystrophin expression in skeletal muscles. To overcome limited packaging capacity of AAV vectors (<5 kb), truncated recombinant microdystrophin genes with deletions of most of rod and carboxyl-terminal (CT) domains of dystrophin have been developed. We have previously shown the efficiency of mRNA sequence-optimized microdystrophin (ΔR4-23/ΔCT, called MD1) with deletion of spectrin-like repeat domain 4 to 23 and CT domain in ameliorating the pathology of dystrophic mdx mice. However, the CT domain of dystrophin is thought to recruit part of the dystrophin-associated protein complex, which acts as a mediator of signaling between extracellular matrix and cytoskeleton in muscle fibers. In this study, we extended the ΔR4-23/ΔCT microdystrophin by incorporating helix 1 of the coiled-coil motif in the CT domain of dystrophin (MD2), which contains the α1-syntrophin and α-dystrobrevin binding sites. Intramuscular injection of AAV2/9 expressing CT domain-extended microdystrophin showed efficient dystrophin expression in tibialis anterior muscles of mdx mice. The presence of the CT domain of dystrophin in MD2 increased the recruitment of α1-syntrophin and α-dystrobrevin at the sarcolemma and significantly improved the muscle resistance to lengthening contraction-induced muscle damage in the mdx mice compared with MD1. These results suggest that the incorporation of helix 1 of the coiled-coil motif in the CT domain of dystrophin to the microdystrophins will substantially improve their efficiency in restoring muscle function in patients with Duchenne muscular dystrophy.Human gene therapy 03/2011; 22(11):1379-88. · 4.20 Impact Factor