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Szwec S, Kapłucha Z, Chamberlain JS, Konieczny P. Dystrophin- and Utrophin-Based Therapeutic Approaches for Treatment of Duchenne Muscular Dystrophy: A Comparative Review. BioDrugs 2024; 38:95-119. [PMID: 37917377 PMCID: PMC10789850 DOI: 10.1007/s40259-023-00632-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2023] [Indexed: 11/04/2023]
Abstract
Duchenne muscular dystrophy is a devastating disease that leads to progressive muscle loss and premature death. While medical management focuses mostly on symptomatic treatment, decades of research have resulted in first therapeutics able to restore the affected reading frame of dystrophin transcripts or induce synthesis of a truncated dystrophin protein from a vector, with other strategies based on gene therapy and cell signaling in preclinical or clinical development. Nevertheless, recent reports show that potentially therapeutic dystrophins can be immunogenic in patients. This raises the question of whether a dystrophin paralog, utrophin, could be a more suitable therapeutic protein. Here, we compare dystrophin and utrophin amino acid sequences and structures, combining published data with our extended in silico analyses. We then discuss these results in the context of therapeutic approaches for Duchenne muscular dystrophy. Specifically, we focus on strategies based on delivery of micro-dystrophin and micro-utrophin genes with recombinant adeno-associated viral vectors, exon skipping of the mutated dystrophin pre-mRNAs, reading through termination codons with small molecules that mask premature stop codons, dystrophin gene repair by clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (CRISPR/Cas9)-mediated genetic engineering, and increasing utrophin levels. Our analyses highlight the importance of various dystrophin and utrophin domains in Duchenne muscular dystrophy treatment, providing insights into designing novel therapeutic compounds with improved efficacy and decreased immunoreactivity. While the necessary actin and β-dystroglycan binding sites are present in both proteins, important functional distinctions can be identified in these domains and some other parts of truncated dystrophins might need redesigning due to their potentially immunogenic qualities. Alternatively, therapies based on utrophins might provide a safer and more effective approach.
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Affiliation(s)
- Sylwia Szwec
- Institute of Human Biology and Evolution, Faculty of Biology, Adam Mickiewicz University, ul. Uniwersytetu Poznańskiego 6, 61-614, Poznań, Poland
| | - Zuzanna Kapłucha
- Institute of Human Biology and Evolution, Faculty of Biology, Adam Mickiewicz University, ul. Uniwersytetu Poznańskiego 6, 61-614, Poznań, Poland
| | - Jeffrey S Chamberlain
- Department of Neurology, University of Washington School of Medicine, Seattle, WA, 98109-8055, USA
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Washington School of Medicine, Seattle, WA, 98109-8055, USA
- Department of Biochemistry, University of Washington School of Medicine, Seattle, WA, 98109-8055, USA
- Department of Medicine, University of Washington School of Medicine, Seattle, WA, 98109-8055, USA
| | - Patryk Konieczny
- Institute of Human Biology and Evolution, Faculty of Biology, Adam Mickiewicz University, ul. Uniwersytetu Poznańskiego 6, 61-614, Poznań, Poland.
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Abstract
Muscular dystrophies are a group of genetic disorders characterized by varying degrees of progressive muscle weakness and degeneration. They are clinically and genetically heterogeneous but share the common histological features of dystrophic muscle. There is currently no cure for muscular dystrophies, which is of particular concern for the more disabling and/or lethal forms of the disease. Through the years, several therapies have encouragingly been developed for muscular dystrophies and include genetic, cellular, and pharmacological approaches. In this chapter, we undertake a comprehensive exploration of muscular dystrophy therapeutics under current development. Our review includes antisense therapy, CRISPR, gene replacement, cell therapy, nonsense suppression, and disease-modifying small molecule compounds.
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Therapeutic potential of highly functional codon-optimized microutrophin for muscle-specific expression. Sci Rep 2022; 12:848. [PMID: 35039573 PMCID: PMC8764061 DOI: 10.1038/s41598-022-04892-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 01/03/2022] [Indexed: 12/26/2022] Open
Abstract
High expectations have been set on gene therapy with an AAV-delivered shortened version of dystrophin (µDys) for Duchenne muscular dystrophy (DMD), with several drug candidates currently undergoing clinical trials. Safety concerns with this therapeutic approach include the immune response to introduced dystrophin antigens observed in some DMD patients. Recent reports highlighted microutrophin (µUtrn) as a less immunogenic functional dystrophin substitute for gene therapy. In the current study, we created a human codon-optimized µUtrn which was subjected to side-by-side characterization with previously reported mouse and human µUtrn sequences after rAAV9 intramuscular injections in mdx mice. Long-term studies with systemic delivery of rAAV9-µUtrn demonstrated robust transgene expression in muscles, with localization to the sarcolemma, functional improvement of muscle performance, decreased creatine kinase levels, and lower immunogenicity as compared to µDys. An extensive toxicity study in wild-type rats did not reveal adverse changes associated with high-dose rAAV9 administration and human codon-optimized µUtrn overexpression. Furthermore, we verified that muscle-specific promoters MHCK7 and SPc5-12 drive a sufficient level of rAAV9-µUtrn expression to ameliorate the dystrophic phenotype in mdx mice. Our results provide ground for taking human codon-optimized µUtrn combined with muscle-specific promoters into clinical development as safe and efficient gene therapy for DMD.
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