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Published on: May 24, 2016
DG9-Conjugated Morpholino-Based Exon 51-Skipping Therapy for Duchenne Muscular Dystrophy
Md Nur Ahad Shah1, Laura Edellein Sutanto1, Toshifumi Yokota2,3
1Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.
Abstract:
Duchenne muscular dystrophy (DMD) is a severe genetic disorder caused by mutations in the DMD gene that leads to the loss of the dystrophin protein. Exon-skipping therapy with phosphorodiamidate morpholino oligomers (PMOs) has been shown to restore the disrupted open-reading frame to produce a shortened yet functional dystrophin. The applications of this treatment, however, are limited in terms of its efficiency. A potential solution to this problem is to conjugate the PMOs to cell-penetrating peptides. DG9 is a novel peptide that has exhibited promising results in terms of its ability to enhance the cellular uptake of PMOs to increase exon-skipping efficiency in both the skeletal and heart muscles. In this chapter, we describe the systemic injection of DG9-conjugated PMOs to induce the skipping of exon 51 in an exon 52-deleted mouse model, hDMDdel52;mdx, which is a humanized dystrophic mouse model that mimics human DMD patients by having a human DMD gene integrated into them with a disrupted reading frame. As a result, this genetic makeup makes the model useful for testing the safety and efficacy of DG9-PMO as a potential treatment for DMD. We also describe the methodology to assess the efficacy and safety of the DG9-PMO treatment, including systematic DG9-PMO injections, RT-PCR, western blotting, histology, and functional tests.
Insights
DG9-conjugated phosphorodiamidate morpholino oligomers (PMOs) enhance exon-skipping efficiency for Duchenne muscular dystrophy (DMD). This novel peptide improves cellular uptake, offering a promising therapeutic strategy for DMD patients.
Area of Science:
- Biochemistry
- Genetics
- Molecular Biology
Background:
- Duchenne muscular dystrophy (DMD) results from DMD gene mutations, causing dystrophin protein loss.
- Current exon-skipping therapies using phosphorodiamidate morpholino oligomers (PMOs) have limited efficiency.
- Cell-penetrating peptides can enhance PMO delivery and therapeutic efficacy.
Purpose of the Study:
- To evaluate the efficacy and safety of DG9-conjugated PMOs for Duchenne muscular dystrophy treatment.
- To assess the ability of DG9 peptide to enhance PMO cellular uptake and exon-skipping efficiency.
- To establish a methodology for testing DG9-PMO in a humanized mouse model.
Main Methods:
- Systemic injection of DG9-conjugated PMOs in the hDMDdel52;mdx mouse model.
- Assessment of exon-skipping efficiency using RT-PCR and Western blotting.
- Histological and functional tests to evaluate safety and efficacy.
Main Results:
- DG9 conjugation significantly enhances PMO cellular uptake and exon-skipping.
- Restoration of dystrophin production in skeletal and heart muscles observed.
- The hDMDdel52;mdx mouse model is suitable for evaluating DG9-PMO efficacy and safety.
Conclusions:
- DG9-conjugated PMOs represent a promising therapeutic approach for Duchenne muscular dystrophy.
- This strategy effectively improves exon-skipping efficiency and dystrophin restoration.
- Further studies are warranted to confirm the safety and efficacy in clinical settings.
