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Effiong UM, Khairandish H, Ramirez-Velez I, Wang Y, Belardi B. Turn-on protein switches for controlling actin binding in cells. Nat Commun 2024; 15:5840. [PMID: 38992021 PMCID: PMC11239668 DOI: 10.1038/s41467-024-49934-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 06/26/2024] [Indexed: 07/13/2024] Open
Abstract
Within a shared cytoplasm, filamentous actin (F-actin) plays numerous and critical roles across the cell body. Cells rely on actin-binding proteins (ABPs) to organize F-actin and to integrate its polymeric characteristics into diverse cellular processes. Yet, the multitude of ABPs that engage with and shape F-actin make studying a single ABP's influence on cellular activities a significant challenge. Moreover, without a means of manipulating actin-binding subcellularly, harnessing the F-actin cytoskeleton for synthetic biology purposes remains elusive. Here, we describe a suite of designed proteins, Controllable Actin-binding Switch Tools (CASTs), whose actin-binding behavior can be controlled with external stimuli. CASTs were developed that respond to different external inputs, providing options for turn-on kinetics and enabling orthogonality and multiplexing. Being genetically encoded, we show that CASTs can be inserted into native protein sequences to control F-actin association locally and engineered into structures to control cell and tissue shape and behavior.
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Affiliation(s)
- Unyime M Effiong
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Hannah Khairandish
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Isabela Ramirez-Velez
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Yanran Wang
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Brian Belardi
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA.
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2
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Effiong UM, Khairandish H, Ramirez-Velez I, Wang Y, Belardi B. Turn-On Protein Switches for Controlling Actin Binding in Cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.26.561921. [PMID: 37961502 PMCID: PMC10634840 DOI: 10.1101/2023.10.26.561921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Within a shared cytoplasm, filamentous actin (F-actin) plays numerous and critical roles across the cell body. Cells rely on actin-binding proteins (ABPs) to organize F-actin and to integrate its polymeric characteristics into diverse cellular processes. Yet, the multitude of ABPs that engage with and shape F-actin make studying a single ABP's influence on cellular activities a significant challenge. Moreover, without a means of manipulating actin-binding subcellularly, harnessing the F-actin cytoskeleton for synthetic biology purposes remains elusive. Here, we describe a suite of designed proteins, Controllable Actin-binding Switch Tools (CASTs), whose actin-binding behavior can be controlled with external stimuli. CASTs were developed that respond to different external inputs, providing options for turn-on kinetics and enabling orthogonality. Being genetically encoded, we show that CASTs can be inserted into native protein sequences to control F-actin association locally and engineered into new structures to control cell and tissue shape and behavior.
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Affiliation(s)
- Unyime M. Effiong
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Hannah Khairandish
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Isabela Ramirez-Velez
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Yanran Wang
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Brian Belardi
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
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3
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Bez Batti Angulski A, Hosny N, Cohen H, Martin AA, Hahn D, Bauer J, Metzger JM. Duchenne muscular dystrophy: disease mechanism and therapeutic strategies. Front Physiol 2023; 14:1183101. [PMID: 37435300 PMCID: PMC10330733 DOI: 10.3389/fphys.2023.1183101] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 05/24/2023] [Indexed: 07/13/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a severe, progressive, and ultimately fatal disease of skeletal muscle wasting, respiratory insufficiency, and cardiomyopathy. The identification of the dystrophin gene as central to DMD pathogenesis has led to the understanding of the muscle membrane and the proteins involved in membrane stability as the focal point of the disease. The lessons learned from decades of research in human genetics, biochemistry, and physiology have culminated in establishing the myriad functionalities of dystrophin in striated muscle biology. Here, we review the pathophysiological basis of DMD and discuss recent progress toward the development of therapeutic strategies for DMD that are currently close to or are in human clinical trials. The first section of the review focuses on DMD and the mechanisms contributing to membrane instability, inflammation, and fibrosis. The second section discusses therapeutic strategies currently used to treat DMD. This includes a focus on outlining the strengths and limitations of approaches directed at correcting the genetic defect through dystrophin gene replacement, modification, repair, and/or a range of dystrophin-independent approaches. The final section highlights the different therapeutic strategies for DMD currently in clinical trials.
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Affiliation(s)
| | | | | | | | | | | | - Joseph M. Metzger
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN, United States
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4
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Boehler JF, Brown KJ, Beatka M, Gonzalez JP, Donisa Dreghici R, Soustek-Kramer M, McGonigle S, Ganot A, Palmer T, Lowie C, Chamberlain JS, Lawlor MW, Morris CA. Clinical potential of microdystrophin as a surrogate endpoint. Neuromuscul Disord 2023; 33:40-49. [PMID: 36575103 DOI: 10.1016/j.nmd.2022.12.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 11/28/2022] [Accepted: 12/13/2022] [Indexed: 12/15/2022]
Abstract
Accelerated approval based on a likely surrogate endpoint can be life-changing for patients suffering from a rare progressive disease with unmet medical need, as it substantially hastens access to potentially lifesaving therapies. In one such example, antisense morpholinos were approved to treat Duchenne muscular dystrophy (DMD) based on measurement of shortened dystrophin in skeletal muscle biopsies as a surrogate biomarker. New, promising therapeutics for DMD include AAV gene therapy to restore another form of dystrophin termed mini- or microdystrophin. AAV-microdystrophins are currently in clinical trials but have yet to be accepted by regulatory agencies as reasonably likely surrogate endpoints. To evaluate microdystrophin expression as a reasonably likely surrogate endpoint for DMD, this review highlights dystrophin biology in the context of functional and clinical benefit to support the argument that microdystrophin proteins have a high probability of providing clinical benefit based on their rational design. Unlike exon-skipping based strategies, the approach of rational design allows for functional capabilities (i.e. quality) of the protein to be maximized with every patient receiving the same optimized microdystrophin. Therefore, the presence of rationally designed microdystrophin in a muscle biopsy is likely to predict clinical benefit and is consequently a strong candidate for a surrogate endpoint analysis to support accelerated approval.
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Affiliation(s)
- Jessica F Boehler
- Solid Biosciences, 500 Rutherford Avenue 3rd Floor, Boston, MA 02129, United States
| | - Kristy J Brown
- Solid Biosciences, 500 Rutherford Avenue 3rd Floor, Boston, MA 02129, United States
| | - Margaret Beatka
- Diverge TSL, 247 Freshwater Way Suite 610, Milwaukee, WI 53204, United States
| | - J Patrick Gonzalez
- Solid Biosciences, 500 Rutherford Avenue 3rd Floor, Boston, MA 02129, United States
| | | | | | - Sharon McGonigle
- Solid Biosciences, 500 Rutherford Avenue 3rd Floor, Boston, MA 02129, United States
| | - Annie Ganot
- Solid Biosciences, 500 Rutherford Avenue 3rd Floor, Boston, MA 02129, United States
| | - Timothy Palmer
- Solid Biosciences, 500 Rutherford Avenue 3rd Floor, Boston, MA 02129, United States
| | - Caitlin Lowie
- Solid Biosciences, 500 Rutherford Avenue 3rd Floor, Boston, MA 02129, United States
| | - Jeffrey S Chamberlain
- Department of Neurology, University of Washington School of Medicine, Seattle, United States
| | - Michael W Lawlor
- Diverge TSL, 247 Freshwater Way Suite 610, Milwaukee, WI 53204, United States
| | - Carl A Morris
- Solid Biosciences, 500 Rutherford Avenue 3rd Floor, Boston, MA 02129, United States.
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5
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Bengtsson NE, Crudele JM, Klaiman JM, Halbert CL, Hauschka SD, Chamberlain JS. Comparison of dystrophin expression following gene editing and gene replacement in an aged preclinical DMD animal model. Mol Ther 2022; 30:2176-2185. [PMID: 35143959 PMCID: PMC9171147 DOI: 10.1016/j.ymthe.2022.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 01/13/2022] [Accepted: 02/03/2022] [Indexed: 11/30/2022] Open
Abstract
Gene editing has shown promise for correcting or bypassing dystrophin mutations in Duchenne muscular dystrophy (DMD). However, preclinical studies have focused on young animals with limited muscle fibrosis and wasting, thereby favoring muscle transduction, myonuclear editing, and prevention of disease progression. Here, we explore muscle-specific dystrophin gene editing following intramuscular delivery of AAV6:CK8e-CRISPR/SaCas9 in 3- and 8-year-old dystrophic CXMD dogs and provide a qualitative comparison to AAV6:CK8e-micro-dystrophin gene replacement at 6 weeks post-treatment. Gene editing restored the dystrophin reading frame in ∼1.3% of genomes and in up to 4.0% of dystrophin transcripts following excision of a 105-kb mutation containing region spanning exons 6-8. However, resulting dystrophin expression levels and effects on muscle pathology were greater with the use of micro-dystrophin gene transfer. This study demonstrates that our muscle-specific multi-exon deletion strategy can correct a frequently mutated region of the dystrophin gene in an aged large animal DMD model, but underscores that further enhancements are required to reach efficiencies comparable to AAV micro-dystrophin. Our observations also indicate that treatment efficacy and state of muscle pathology at the time of intervention are linked, suggesting the need for additional methodological optimizations related to age and disease progression to achieve relevant clinical translation of CRISPR-based therapies to all DMD patients.
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Affiliation(s)
- Niclas E Bengtsson
- 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.
| | - Julie M Crudele
- 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
| | - Jordan M Klaiman
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Washington School of Medicine, Seattle, WA 98109-8055, USA; Department of Rehabilitation Medicine, University of Washington School of Medicine, Seattle, WA 98109-8055, USA
| | - Christine L Halbert
- 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
| | - Stephen D Hauschka
- 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
| | - 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
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6
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Gibbs EM, Barthélémy F, Douine ED, Hardiman NC, Shieh PB, Khanlou N, Crosbie RH, Nelson SF, Miceli MC. Large in-frame 5' deletions in DMD associated with mild Duchenne muscular dystrophy: Two case reports and a review of the literature. Neuromuscul Disord 2019; 29:863-873. [PMID: 31672265 PMCID: PMC7092699 DOI: 10.1016/j.nmd.2019.09.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 08/28/2019] [Accepted: 09/10/2019] [Indexed: 10/26/2022]
Abstract
Duchenne muscular dystrophy is caused by mutations in the dystrophin-encoding DMD gene. While Duchenne is most commonly caused by large intragenic deletions that cause frameshift and complete loss of dystrophin expression, in-frame deletions in DMD can result in the expression of internally truncated dystrophin proteins and may be associated with a milder phenotype. In this study, we describe two individuals with large in-frame 5' deletions (exon 3-23 and exon 3-28) that remove the majority of the N-terminal region, including part of the actin binding and central rod domains. Both patients had progressive muscle weakness during childhood but are observed to have a relatively mild disease course compared to typical Duchenne. We show that in muscle biopsies from both patients, truncated dystrophin is expressed at the sarcolemma. We have additionally developed a patient-specific fibroblast-derived cell model, which can be inducibly reprogrammed to form myotubes that largely recapitulate biopsy findings for the patient with the exon 3-23 deletion, providing a culture model for future investigation of this unusual case. We discuss these mutations in the context of previously reported 5' in-frame DMD deletions and relevant animal models, and review the spectrum of phenotypes associated with these deletions.
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Affiliation(s)
- Elizabeth M Gibbs
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA; Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA
| | - Florian Barthélémy
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Emilie D Douine
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Natalie C Hardiman
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Perry B Shieh
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, 90095, USA
| | - Negar Khanlou
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Rachelle H Crosbie
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA; Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, 90095, USA; Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
| | - Stanley F Nelson
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA; Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, 90095, USA
| | - M Carrie Miceli
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA.
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7
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Bar L, Czosnek H, Sobol I, Ghanim M, Hariton Shalev A. Downregulation of dystrophin expression in pupae of the whitefly Bemisia tabaci inhibits the emergence of adults. INSECT MOLECULAR BIOLOGY 2019; 28:662-675. [PMID: 30834620 DOI: 10.1111/imb.12579] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The whitefly Bemisia tabaci is a major pest to agriculture. Adults are able to fly for long distances and to colonize staple crops, herbs and ornamentals, and to vector viruses belonging to several important taxonomic groups. During their early development, whiteflies mature from eggs through several nymphal stages (instars I to IV) until adults emerge from pupae. We aim at reducing whitefly populations by inhibiting the emergence of adults from nymphs. Here we targeted dystrophin, a conserved protein essential for the development of the muscle system in humans, other animals and insects. We have exploited the fact that whitefly nymphs developing on tomato leaves feed from the plant phloem via their stylets. Thus, we delivered dystrophin-silencing double-stranded RNA to nymphs developing on leaves of tomato plantlets with their roots bathing in the silencing solution. Downregulation of dystrophin expression occurred mainly in pupae. Dystrophin silencing induced also the downregulation of the dystrophin-associated protein genes actin and tropomyosin, and disrupted F-actin. Most significantly, the treatment inhibited the emergence of adults from pupae, suggesting that targeting dystrophin may help to restrain whitefly populations. This study demonstrates for the first time the important role of dystrophin in the development of a major insect pest to agriculture.
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Affiliation(s)
- L Bar
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - H Czosnek
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - I Sobol
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - M Ghanim
- Department of Entomology, Volcani Center, ARO, Rishon LeZion, Israel
| | - A Hariton Shalev
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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8
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Ramos JN, Hollinger K, Bengtsson NE, Allen JM, Hauschka SD, Chamberlain JS. Development of Novel Micro-dystrophins with Enhanced Functionality. Mol Ther 2019; 27:623-635. [PMID: 30718090 PMCID: PMC6403485 DOI: 10.1016/j.ymthe.2019.01.002] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/03/2019] [Accepted: 01/07/2019] [Indexed: 01/24/2023] Open
Abstract
Gene therapies using adeno-associated viral (AAV) vectors have advanced into clinical trials for several diseases, including Duchenne muscular dystrophy (DMD). A limitation of AAV is the carrying capacity (∼5 kb) available for genes and regulatory cassettes (RCs). These size constraints are problematic for the 2.2-Mb dystrophin gene. We previously designed a variety of miniaturized micro-dystrophins (μDys) that displayed significant, albeit incomplete, function in striated muscles. To develop μDys proteins with improved performance, we explored structural modifications of the dystrophin central rod domain. Eight μDys variants were studied that carried unique combinations of between four and six of the 24 spectrin-like repeats present in the full-length protein, as well as various hinge domains. Expression of μDys was regulated by a strong but compact muscle-restricted RC (CK8e) or by the ubiquitously active cytomegalovirus (CMV) RC. Vectors were evaluated by intramuscular injection and systemic delivery to dystrophic mdx4cv mice, followed by analysis of skeletal muscle pathophysiology. Two μDys designs were identified that led to increased force generation compared with previous μDys while also localizing neuronal nitric oxide synthase to the sarcolemma. An AAV vector expressing the smaller of these (μDys5) from the CK8e RC is currently being evaluated in a DMD clinical trial.
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Affiliation(s)
- Julian N Ramos
- Molecular and Cellular Biology Program, University of Washington School of Medicine, Seattle, WA 98195, USA; Department of Neurology, University of Washington School of Medicine, Seattle, WA 98195, USA; Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, Seattle, WA 98195, USA
| | - Katrin Hollinger
- Department of Neurology, University of Washington School of Medicine, Seattle, WA 98195, USA; Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, Seattle, WA 98195, USA
| | - Niclas E Bengtsson
- Department of Neurology, University of Washington School of Medicine, Seattle, WA 98195, USA; Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, Seattle, WA 98195, USA
| | - James M Allen
- Department of Neurology, University of Washington School of Medicine, Seattle, WA 98195, USA; Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, Seattle, WA 98195, USA
| | - Stephen D Hauschka
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, Seattle, WA 98195, USA; Department of Biochemistry, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Jeffrey S Chamberlain
- Molecular and Cellular Biology Program, University of Washington School of Medicine, Seattle, WA 98195, USA; Department of Neurology, University of Washington School of Medicine, Seattle, WA 98195, USA; Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, Seattle, WA 98195, USA; Department of Biochemistry, University of Washington School of Medicine, Seattle, WA 98195, USA; Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA.
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9
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Abstract
Dystrophin is the largest protein isoform (427 kDa) expressed from the gene defective in Duchenne muscular dystrophy, a lethal muscle-wasting and genetically inherited disease. Dystrophin, localized within a cytoplasmic lattice termed costameres, connects the intracellular cytoskeleton of a myofiber through the cell membrane (sarcolemma) to the surrounding extracellular matrix. In spite of its mechanical regulation roles in stabilizing the sarcolemma during muscle contraction, the underlying molecular mechanism is still elusive. Here, we systematically investigated the mechanical stability and kinetics of the force-bearing central domain of human dystrophin that contains 24 spectrin repeats using magnetic tweezers. We show that the stochastic unfolding and refolding of central domain of dystrophin is able to keep the forces below 25 pN over a significant length change up to ∼800 nm in physiological level of pulling speeds. These results suggest that dystrophin may serve as a molecular shock absorber that defines the physiological level of force in the dystrophin-mediated force-transmission pathway during muscle contraction/stretch, thereby stabilizing the sarcolemma.
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Affiliation(s)
- Shimin Le
- Department of Physics, National University of Singapore, Singapore, 117551
| | - Miao Yu
- Mechanobiology Institute, National University of Singapore, Singapore, 117411
| | - Ladislav Hovan
- Mechanobiology Institute, National University of Singapore, Singapore, 117411
| | - Zhihai Zhao
- Department of Physics, National University of Singapore, Singapore, 117551
| | - James Ervasti
- College of Biological Sciences, University of Minnesota, MN, USA, 55455
| | - Jie Yan
- Department of Physics, National University of Singapore, Singapore, 117551
- Mechanobiology Institute, National University of Singapore, Singapore, 117411
- Centre for BioImaging Sciences, National University of Singapore, Singapore, 117546
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10
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Mavrogeni SI, Markousis-Mavrogenis G, Papavasiliou A, Papadopoulos G, Kolovou G. Cardiac Involvement in Duchenne Muscular Dystrophy and Related Dystrophinopathies. Methods Mol Biol 2018; 1687:31-42. [PMID: 29067654 DOI: 10.1007/978-1-4939-7374-3_3] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Dystrophinopathies include Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), X-linked dilated cardiomyopathy (XLCM), and facioscapulohumeral muscular dystrophy (FSHD). DMD/BMD are X-linked recessive disorders, related to the synthesis of dystrophin. Most of DMD after the third decade of their age develop cardiomyopathy that remains silent, due to relative physical inactivity. Cardiac disease in female carriers presents with hypertrophy, arrhythmias or dilated cardiomyopathy, clinically overt by increasing age.In ECG, DMD presents increased R/S ratio in the right precordial leads, deep Q waves in the lateral leads, conduction abnormalities, and arrhythmias. Echocardiography, although widely available and inexpensive, is highly depended on the acoustic window and operator's experience. Tissue Doppler can be used to identify early changes of cardiomyopathy and detect progressive cardiac damage. CMR, a noninvasive, nonradiating technique, by evaluation of cardiac volumes, mass, ejection fraction, inflammation, and fibrosis, is ideal for early diagnosis. Subepicardial fibrosis in the inferolateral wall is the typical CMR lesion in DMD/BMD.Early initiation of angiotensin converting enzyme inhibitors (ACEI) treatment, such as perindopril, was associated with lower mortality in DMD with normal LV ejection fraction at study entry. Other studies documented that a beta-blocker (BB), in addition to ACEI, improves LV systolic function in MD. These encouraging results recommend initiation of ACEI and/or BB early after diagnosis of the muscular dystrophy, especially in DMD.
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MESH Headings
- Adolescent
- Adrenergic beta-Antagonists/therapeutic use
- Angiotensin-Converting Enzyme Inhibitors/therapeutic use
- Arrhythmias, Cardiac/diagnosis
- Arrhythmias, Cardiac/drug therapy
- Arrhythmias, Cardiac/physiopathology
- Cardiomyopathies/diagnosis
- Cardiomyopathies/drug therapy
- Cardiomyopathies/genetics
- Cardiomyopathies/physiopathology
- Cardiomyopathy, Dilated/diagnosis
- Cardiomyopathy, Dilated/drug therapy
- Cardiomyopathy, Dilated/genetics
- Cardiomyopathy, Dilated/physiopathology
- Dystrophin/genetics
- Echocardiography
- Electrocardiography
- Female
- Heart/physiopathology
- Humans
- Male
- Muscular Dystrophy, Duchenne/diagnosis
- Muscular Dystrophy, Duchenne/drug therapy
- Muscular Dystrophy, Duchenne/genetics
- Muscular Dystrophy, Duchenne/physiopathology
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Affiliation(s)
- Sophie I Mavrogeni
- Onassis Cardiac Surgery Center, 50 Esperou Street, 175-61 P.Faliro, Athens, Greece.
| | | | | | | | - Genovefa Kolovou
- Onassis Cardiac Surgery Center, 50 Esperou Street, 175-61 P.Faliro, Athens, Greece
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11
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Mavrogeni S, Papavasiliou A, Giannakopoulou K, Markousis-Mavrogenis G, Pons MR, Karanasios E, Nikas I, Papadopoulos G, Kolovou G, Chrousos GP. Oedema-fibrosis in Duchenne Muscular Dystrophy: Role of cardiovascular magnetic resonance imaging. Eur J Clin Invest 2017; 47. [PMID: 29027210 DOI: 10.1111/eci.12843] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 10/09/2017] [Indexed: 12/13/2022]
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked muscle disorder characterized by progressive, irreversible loss of cardiac and skeletal muscular function. Muscular enlargement in DMD is attributed to oedema, due to the increased cytoplasmic Na+ concentration. The aim of this review was to present the current experience and emphasize the role of cardiovascular magnetic resonance (CMR) in the diagnosis of this condition. DMD patients' survival depends on ventilatory assistance, as respiratory muscle dysfunction was the most common cause of death in the past. Currently, due to improved ventilatory assistance, cardiomyopathy has become the main cause of death, even though clinically overt heart failure may be absent. CMR is the technique of choice to assess the pathophysiologic phenomena taking place in DMD, such as myocardial oedema and subepicardial fibrosis. The classic index to assess oedema is the T2-weighted short-tau inversion recovery (T2w-STIR), as it suppresses the signal from flowing blood and resident fat and enhances sensitivity to tissue fluid. Furthermore, CMR is the most reliable technique to detect and quantify fibrosis in DMD. Recently, the new indices T2, T1 mapping (native and postcontrast) and the extracellular volume (ECV) allow a more accurate approach of myocardial oedema and fibrosis. To conclude, the assessment of cardiac oedema and subepicardial fibrosis in the inferolateral wall of the left heart ventricle are the most important early finding in DMD with preserved ventricular function, and CMR, using both the classic and the new indices, is the best technique to detect and monitor these lesions.
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Affiliation(s)
| | | | - Katerina Giannakopoulou
- First Dept of Paediatrics, National and Kapodistrian University of Athens, Aghia Sophia Children's Hospital, Athens, Greece
| | | | - Maria Roser Pons
- First Dept of Paediatrics, National and Kapodistrian University of Athens, Aghia Sophia Children's Hospital, Athens, Greece
| | - Evangelos Karanasios
- First Dept of Paediatrics, National and Kapodistrian University of Athens, Aghia Sophia Children's Hospital, Athens, Greece
| | - Ioannis Nikas
- First Dept of Paediatrics, National and Kapodistrian University of Athens, Aghia Sophia Children's Hospital, Athens, Greece
| | - George Papadopoulos
- First Dept of Paediatrics, National and Kapodistrian University of Athens, Aghia Sophia Children's Hospital, Athens, Greece
| | | | - George P Chrousos
- First Dept of Paediatrics, National and Kapodistrian University of Athens, Aghia Sophia Children's Hospital, Athens, Greece
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12
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Mavrogeni S, Pons R, Nikas I, Papadopoulos G, Verganelakis DA, Kolovou G, Chrousos GP. Brain and heart magnetic resonance imaging/spectroscopy in duchenne muscular dystrophy. Eur J Clin Invest 2017; 47. [PMID: 28981141 DOI: 10.1111/eci.12842] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 10/02/2017] [Indexed: 01/04/2023]
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked muscle disorder characterized by progressive and irreversible loss of muscular function. As muscular disease progresses, the repair mechanisms cannot compensate for cellular damage, leading inevitably to necrosis and progressive replacement by fibrous and fatty tissue. Cardiomyopathy and respiratory failure are the main causes of death in DMD. In addition to the well-described muscle and heart disease, cognitive dysfunction affects around 30% of DMD boys. Myocardial fibrosis, assessed by late gadolinium enhancement (LGE), using cardiovascular magnetic resonance imaging (CMR), is an early marker of heart involvement in both DMD patients and female carriers. In parallel, brain MRI identifies smaller total brain volume, smaller grey matter volume, lower white matter fractional anisotropy and higher white matter radial diffusivity in DMD patients. The in vivo brain evaluation of mdx mice, a surrogate animal model of DMD, showed an increased inorganic phosphate (P(i))/phosphocreatine (PCr) and pH. In this paper, we propose a holistic approach using techniques of magnetic resonance imaging, spectroscopy and diffusion tensor imaging as a tool to create a "heart and brain imaging map" in DMD patients that could potentially facilitate the patients' risk stratification and also future research studies in the field.
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Affiliation(s)
| | - Roser Pons
- 1st Department of Pediatrics, National and Kapodistrian University of Athens, Aghia Sophia Children's Hospital, Athens, Greece
| | - Ioannis Nikas
- 1st Department of Pediatrics, National and Kapodistrian University of Athens, Aghia Sophia Children's Hospital, Athens, Greece
| | - George Papadopoulos
- 1st Department of Pediatrics, National and Kapodistrian University of Athens, Aghia Sophia Children's Hospital, Athens, Greece
| | - Dimitrios A Verganelakis
- 1st Department of Pediatrics, National and Kapodistrian University of Athens, Aghia Sophia Children's Hospital, Athens, Greece
| | | | - George P Chrousos
- 1st Department of Pediatrics, National and Kapodistrian University of Athens, Aghia Sophia Children's Hospital, Athens, Greece
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13
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Kyrychenko V, Kyrychenko S, Tiburcy M, Shelton JM, Long C, Schneider JW, Zimmermann WH, Bassel-Duby R, Olson EN. Functional correction of dystrophin actin binding domain mutations by genome editing. JCI Insight 2017; 2:95918. [PMID: 28931764 DOI: 10.1172/jci.insight.95918] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 08/15/2017] [Indexed: 12/26/2022] Open
Abstract
Dystrophin maintains the integrity of striated muscles by linking the actin cytoskeleton with the cell membrane. Duchenne muscular dystrophy (DMD) is caused by mutations in the dystrophin gene (DMD) that result in progressive, debilitating muscle weakness, cardiomyopathy, and a shortened lifespan. Mutations of dystrophin that disrupt the amino-terminal actin-binding domain 1 (ABD-1), encoded by exons 2-8, represent the second-most common cause of DMD. In the present study, we compared three different strategies for CRISPR/Cas9 genome editing to correct mutations in the ABD-1 region of the DMD gene by deleting exons 3-9, 6-9, or 7-11 in human induced pluripotent stem cells (iPSCs) and by assessing the function of iPSC-derived cardiomyocytes. All three exon deletion strategies enabled the expression of truncated dystrophin protein and restoration of cardiomyocyte contractility and calcium transients to varying degrees. We show that deletion of exons 3-9 by genomic editing provides an especially effective means of correcting disease-causing ABD-1 mutations. These findings represent an important step toward eventual correction of common DMD mutations and provide a means of rapidly assessing the expression and function of internally truncated forms of dystrophin-lacking portions of ABD-1.
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Affiliation(s)
- Viktoriia Kyrychenko
- Department of Molecular Biology.,Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, and.,Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Sergii Kyrychenko
- Department of Molecular Biology.,Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, and.,Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Malte Tiburcy
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - John M Shelton
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Chengzu Long
- Department of Molecular Biology.,Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, and.,Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Jay W Schneider
- Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, and.,Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Wolfram-Hubertus Zimmermann
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Rhonda Bassel-Duby
- Department of Molecular Biology.,Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, and.,Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Eric N Olson
- Department of Molecular Biology.,Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, and.,Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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14
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Papa AA, D'Ambrosio P, Petillo R, Palladino A, Politano L. Heart transplantation in patients with dystrophinopathic cardiomyopathy: Review of the literature and personal series. Intractable Rare Dis Res 2017; 6:95-101. [PMID: 28580208 PMCID: PMC5451754 DOI: 10.5582/irdr.2017.01024] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Cardiomyopathy associated with dystrophinopathies [Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), X-linked dilated cardiomyopathy (XL-dCM) and cardiomyopathy of Duchenne/Becker (DMD/BMD) carriers] is an increasing recognized manifestation of these neuromuscular disorders and notably contributes to their morbidity and mortality. Dystrophinopathic cardiomyopathy (DCM) is the result of the dystrophin protein deficiency at the myocardium level, parallel to the deficiency occurring at the skeletal muscle level. It begins as a "presymptomatic" stage in the first decade of life and evolves in a stepwise manner toward pictures of overt cardiomyopathy (hypertrophic stage, arrhythmogenic stage and dilated cardiomyopathy). The final stage caused by the extensive loss of cardiomyocytes results in an irreversible cardiac failure, characterized by frequent episodes of acute congestive heart failure (CHF), despite a correct pharmacological treatment. The picture of a severe dilated cardiomyopathy with intractable heart failure is typical of BMD, XL-dCM and cardiomyopathy of DMD/BMD carriers, while it is less frequently observed in patients with DMD. Heart transplantation (HT) is the only curative therapy for patients with dystrophinopathic end-stage heart failure who remain symptomatic despite an optimal medical therapy. However, no definitive figures exist in literature concerning the number of patients with DCM transplanted, and their outcome. This overview is to summarize the clinical outcomes so far published on the topic, to report the personal series of dystrophinopathic patients receiving heart transplantation and finally to provide evidence that heart transplantation is a safe and effective treatment for selected patients with end-stage DCM.
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Affiliation(s)
- Andrea Antonio Papa
- Cardiomyology and Medical Genetics, Department of Experimental Medicine, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Paola D'Ambrosio
- Cardiomyology and Medical Genetics, Department of Experimental Medicine, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Roberta Petillo
- Cardiomyology and Medical Genetics, Department of Experimental Medicine, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Alberto Palladino
- Cardiomyology and Medical Genetics, Department of Experimental Medicine, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Luisa Politano
- Cardiomyology and Medical Genetics, Department of Experimental Medicine, University of Campania “Luigi Vanvitelli”, Naples, Italy
- Address correspondence to: Prof. Luisa Politano, Cardiomiologia e Genetica Medica, Dipartimento di Medicina Sperimentale, Primo Policlinico, Piazza Miraglia, Napoli 80138, Italy. E-mail:
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15
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Deletion of exons 3−9 encompassing a mutational hot spot in the DMD gene presents an asymptomatic phenotype, indicating a target region for multiexon skipping therapy. J Hum Genet 2016; 61:663-7. [DOI: 10.1038/jhg.2016.28] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 01/22/2016] [Accepted: 02/26/2016] [Indexed: 11/08/2022]
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Abstract
INTRODUCTION Duchenne muscular dystrophy (DMD) is a relatively common inherited disorder caused by defective expression of the protein dystrophin. The most direct approach to treating this disease would be to restore dystrophin production in muscle. Recent progress has greatly increased the prospects for successful gene therapy of DMD, and here we summarize the most promising developments. AREAS COVERED Gene transfer using vectors derived from adeno-associated virus (AAV) has emerged as a promising method to restore dystrophin production in muscles bodywide, and represents a treatment option applicable to all DMD patients. Using information gleaned from PubMed searches of the literature, attendance at scientific conferences and results from our own lab, we provide an overview of the potential for gene therapy of DMD using AAV vectors including a summary of promising developments and issues that need to be resolved prior to large-scale therapeutic implementation. EXPERT OPINION Of the many approaches being pursued to treat DMD and BMD, gene therapy based on AAV-mediated delivery of microdystrophin is the most direct and promising method to treat the cause of the disorder. The major challenges to this approach are ensuring that microdystrophin can be delivered safely and efficiently without eliciting an immune response.
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Affiliation(s)
- Julian Ramos
- University of Washington, Wellstone Muscular Dystrophy Research Center, Department of Neurology, Seattle, WA, 98195-7720, USA
| | - Jeffrey S Chamberlain
- University of Washington, Wellstone Muscular Dystrophy Research Center, Department of Neurology, Seattle, WA, 98195-7720, USA
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17
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Wein N, Vulin A, Sofia Falzarano M, Al-Khalili Szigyarto C, Maiti B, Findlay A, Heller KN, Uhlén M, Bakthavachalu B, Messina S, Vita G, Passarelli C, Gualandi F, Wilton SD, Rodino-Klapac L, Yang L, Dunn DM, Schoenberg D, Weiss RB, Howard MT, Ferlini A, Flanigan KM. Translation from a DMD exon 5 IRES results in a functional dystrophin isoform that attenuates dystrophinopathy in humans and mice. Nat Med 2014; 20:992-1000. [PMID: 25108525 PMCID: PMC4165597 DOI: 10.1038/nm.3628] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 06/05/2014] [Indexed: 12/26/2022]
Abstract
Most mutations that truncate the reading frame of the DMD gene cause loss of dystrophin expression and lead to Duchenne muscular dystrophy. However, amelioration of disease severity has been shown to result from alternative translation initiation beginning in DMD exon 6 that leads to expression of a highly functional N-truncated dystrophin. Here we demonstrate that this isoform results from usage of an internal ribosome entry site (IRES) within exon 5 that is glucocorticoid inducible. We confirmed IRES activity by both peptide sequencing and ribosome profiling in muscle from individuals with minimal symptoms despite the presence of truncating mutations. We generated a truncated reading frame upstream of the IRES by exon skipping, which led to synthesis of a functional N-truncated isoform in both human subject-derived cell lines and in a new DMD mouse model, where expression of the truncated isoform protected muscle from contraction-induced injury and corrected muscle force to the same level as that observed in control mice. These results support a potential therapeutic approach for patients with mutations within the 5' exons of DMD.
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Affiliation(s)
- Nicolas Wein
- The Center for Gene Therapy, Nationwide Children’s Hospital; The Ohio State University, Columbus, Ohio, USA
| | - Adeline Vulin
- The Center for Gene Therapy, Nationwide Children’s Hospital; The Ohio State University, Columbus, Ohio, USA
| | - Maria Sofia Falzarano
- Section of Microbiology and Medical Genetics, Department of Medical Sciences, University of Ferrara, Ferrara, Italy
| | - Christina Al-Khalili Szigyarto
- Department of Proteomics and Nanobiotechnology, School of Biotechnology, KTH-Royal Institute of Technology, Stockholm, Sweden
| | - Baijayanta Maiti
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri
| | - Andrew Findlay
- The Center for Gene Therapy, Nationwide Children’s Hospital; The Ohio State University, Columbus, Ohio, USA
| | - Kristin N Heller
- The Center for Gene Therapy, Nationwide Children’s Hospital; The Ohio State University, Columbus, Ohio, USA
| | - Mathias Uhlén
- Department of Proteomics and Nanobiotechnology, School of Biotechnology, KTH-Royal Institute of Technology, Stockholm, Sweden
| | - Baskar Bakthavachalu
- Center for RNA Biology and Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Sonia Messina
- Department of Neuroscience, University of Messina and Centro Clinico Nemo Sud, Messina, Italy
| | - Giuseppe Vita
- Department of Neuroscience, University of Messina and Centro Clinico Nemo Sud, Messina, Italy
| | | | - Francesca Gualandi
- Section of Microbiology and Medical Genetics, Department of Medical Sciences, University of Ferrara, Ferrara, Italy
| | - Steve D Wilton
- Centre for Comparative Genomics, Murdoch University, Perth, Australia
| | - Louise Rodino-Klapac
- The Center for Gene Therapy, Nationwide Children’s Hospital; The Ohio State University, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
| | - Lin Yang
- Division of Biomedical Informatics, Department of Computer Science, University of Kentucky Lexington, Kentucky, USA
| | - Diane M. Dunn
- Department of Human Genetics, The University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Daniel Schoenberg
- Center for RNA Biology and Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Robert B. Weiss
- Department of Human Genetics, The University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Michael T. Howard
- Department of Human Genetics, The University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Alessandra Ferlini
- Section of Microbiology and Medical Genetics, Department of Medical Sciences, University of Ferrara, Ferrara, Italy
| | - Kevin M. Flanigan
- The Center for Gene Therapy, Nationwide Children’s Hospital; The Ohio State University, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
- Department of Neurology, The Ohio State University, Columbus, Ohio, USA
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18
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Seto JT, Ramos JN, Muir L, Chamberlain JS, Odom GL. Gene replacement therapies for duchenne muscular dystrophy using adeno-associated viral vectors. Curr Gene Ther 2012; 12:139-51. [PMID: 22533379 DOI: 10.2174/156652312800840603] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 04/16/2012] [Accepted: 04/17/2012] [Indexed: 12/12/2022]
Abstract
The muscular dystrophies collectively represent a major health challenge, as few significant treatment options currently exist for any of these disorders. Recent years have witnessed a proliferation of novel approaches to therapy, spanning increased testing of existing and new pharmaceuticals, DNA delivery (both anti-sense oligonucleotides and plasmid DNA), gene therapies and stem cell technologies. While none of these has reached the point of being used in clinical practice, all show promise for being able to impact different types of muscular dystrophies. Our group has focused on developing direct gene replacement strategies to treat recessively inherited forms of muscular dystrophy, particularly Duchenne and Becker muscular dystrophy (DMD/BMD). Both forms of dystrophy are caused by mutations in the dystrophin gene and all cases can in theory be treated by gene replacement using synthetic forms of the dystrophin gene. The major challenges for success of this approach are the development of a suitable gene delivery shuttle, generating a suitable gene expression cassette able to be carried by such a shuttle, and achieving safe and effective delivery without elicitation of a destructive immune response. This review summarizes the current state of the art in terms of using adeno-associated viral vectors to deliver synthetic dystrophin genes for the purpose of developing gene therapy for DMD.
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Affiliation(s)
- Jane T Seto
- Department of Neurology, University of Washington, Seattle, WA 98195-7720, USA.
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Yokota T, Duddy W, Echigoya Y, Kolski H. Exon skipping for nonsense mutations in Duchenne muscular dystrophy: too many mutations, too few patients? Expert Opin Biol Ther 2012; 12:1141-52. [PMID: 22650324 DOI: 10.1517/14712598.2012.693469] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Duchenne muscular dystrophy (DMD), one of the most common and lethal genetic disorders, is caused by mutations of the dystrophin gene. Removal of an exon or of multiple exons using antisense molecules has been demonstrated to allow synthesis of truncated 'Becker muscular dystrophy-like' dystrophin. AREAS COVERED Approximately 15% of DMD cases are caused by a nonsense mutation. Although patient databases have previously been surveyed for applicability to each deletion mutation pattern, this is not so for nonsense mutations. Here, we examine the world-wide database containing notations for more than 1200 patients with nonsense mutations. Approximately 47% of nonsense mutations can be potentially treated with single exon skipping, rising to 90% with double exon skipping, but to reach this proportion requires the development of exon skipping molecules targeting some 68 of dystrophin's 79 exons, with patient numbers spread thinly across those exons. In this review, we discuss progress and remaining hurdles in exon skipping and an alternative strategy, stop-codon readthrough. EXPERT OPINION Antisense-mediated exon skipping therapy is targeted highly at the individual patient and is a clear example of personalized medicine. An efficient regulatory path for drug approval will be a key to success.
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Affiliation(s)
- Toshifumi Yokota
- University of Alberta, Department of Medical Genetics, School of Human Development, Faculty of Medicine and Dentistry, 829 Medical Sciences Building, Edmonton, AB T6G 2H7, Canada.
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Verhaert D, Richards K, Rafael-Fortney JA, Raman SV. Cardiac involvement in patients with muscular dystrophies: magnetic resonance imaging phenotype and genotypic considerations. Circ Cardiovasc Imaging 2011; 4:67-76. [PMID: 21245364 DOI: 10.1161/circimaging.110.960740] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- David Verhaert
- Davis Heart and Lung Research Institute, Ohio State University, Columbus, Ohio, USA
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Post-Natal knockdown of fukutin-related protein expression in muscle by long-termRNA interference induces dystrophic pathology [corrected]. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 178:261-72. [PMID: 21224063 DOI: 10.1016/j.ajpath.2010.11.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 08/08/2010] [Accepted: 09/08/2010] [Indexed: 01/15/2023]
Abstract
Limb-girdle muscular dystrophy 2I (LGMD2I) is caused by mutations in the fukutin-related protein (FKRP) gene. Unlike its severe allelic forms, LGMD2I usually involves slower onset and milder course without defects in the central nervous system. The lack of viable animal models that closely recapitulate LGMD2I clinical phenotypes led us to use RNA interference technology to knock down FKRP expression via postnatal gene delivery so as to circumvent embryonic lethality. Specifically, an adeno-associated viral vector was used to deliver short hairpin (shRNA) genes to healthy ICR mice. Adeno-associated viral vectors expressing a single shRNA or two different shRNAs were injected one time into the hind limb muscles. We showed that FKRP expression at 10 months postinjection was reduced by about 50% with a single shRNA and by 75% with the dual shRNA cassette. Dual-cassette injection also reduced a-dystroglycan glycosylation and its affinity to laminin by up to 70% and induced α-dystrophic pathology, including fibrosis and central nucleation, in more than 50% of the myofibers at 10 months after injection. These results suggest that the reduction of approximately or more than 75% of the normal level of FKRP expression induces chronic dystrophic phenotypes in skeletal muscles. Furthermore, the restoration of about 25% of the normal FKRP level could be sufficient for LGMD2I therapy to correct the genetic deficiency effectively and prevent dystrophic pathology.
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Dystrophin: more than just the sum of its parts. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1804:1713-22. [PMID: 20472103 DOI: 10.1016/j.bbapap.2010.05.001] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 04/30/2010] [Accepted: 05/03/2010] [Indexed: 01/05/2023]
Abstract
Dystrophin is one of a number of large cytoskeleton associated proteins that connect between various cytoskeletal elements and often are tethered to the membrane through other transmembrane protein complexes. These cytolinker proteins often provide structure and support to the cells where they are expressed, and mutations in genes encoding these proteins frequently gives rise to disease. Dystrophin is no exception in any of these respects, providing connections between a transmembrane complex known as the dystrophin-glycoprotein complex and the underlying cytoskeleton. The most established connection and possibly the most important is that to F-actin, but more recently evidence has been forthcoming of connections to membrane phospholipids, intermediate filaments and microtubules. Moreover it is becoming increasingly clear that the multiple spectrin-like repeats in the centre of the molecule, that had hitherto been thought to be largely redundant, harbour binding activities that have a significant impact on dystrophin functionality. This functionality is particularly apparent when assessed by the ability to rescue the dystrophic phenotype in mdx mice. This review will focus on the relatively neglected but functionally vital coiled-coil region of dystrophin, highlighting the structural relationships and interactions of the coiled-coil region and providing new insights into the functional role of this region.
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23
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Arechavala-Gomeza V, Kinali M, Feng L, Guglieri M, Edge G, Main M, Hunt D, Lehovsky J, Straub V, Bushby K, Sewry CA, Morgan JE, Muntoni F. Revertant fibres and dystrophin traces in Duchenne muscular dystrophy: Implication for clinical trials. Neuromuscul Disord 2010; 20:295-301. [DOI: 10.1016/j.nmd.2010.03.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 02/17/2010] [Accepted: 03/05/2010] [Indexed: 10/19/2022]
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Abstract
The muscular dystrophies are a group of neuromuscular disorders associated with muscle weakness and wasting, which in many forms can lead to loss of ambulation and premature death. A number of muscular dystrophies are associated with loss of proteins required for the maintenance of muscle membrane integrity, in particular with proteins that comprise the dystrophin-associated glycoprotein (DAG) complex. Proper glycosylation of O-linked mannose chains on alpha-dystroglycan, a DAG member, is required for the binding of the extracellular matrix to dystroglycan and for proper DAG function. A number of congenital disorders of glycosylation have now been described where alpha-dystroglycan glycosylation is altered and where muscular dystrophy is a predominant phenotype. Glycosylation is also increasingly being appreciated as a genetic modifier of disease phenotypes in many forms of muscular dystrophy and as a target for the development of new therapies. Here we will review the mouse models available for the study of this group of diseases and outline the methodologies required to describe disease phenotypes.
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25
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Kee AJ, Gunning PW, Hardeman EC. Diverse roles of the actin cytoskeleton in striated muscle. J Muscle Res Cell Motil 2009; 30:187-97. [PMID: 19997772 DOI: 10.1007/s10974-009-9193-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 11/24/2009] [Indexed: 12/14/2022]
Abstract
In addition to the highly specialized contractile apparatus, it is becoming increasingly clear that there is an extensive actin cytoskeleton which underpins a wide range of functions in striated muscle. Isoforms of cytoskeletal actin and actin-associated proteins (non-muscle myosins, cytoskeletal tropomyosins, and cytoskeletal alpha-actinins) have been detected in a number of regions of striated muscle: the sub-sarcolemmal costamere, the Z-disc and the T-tubule/sarcoplasmic reticulum membranes. As the only known function of these proteins is through association with actin filaments, their presence in striated muscles indicates that there are spatially and functionally distinct cytoskeletal actin filament systems in these tissues. These filaments are likely to have important roles in mechanical support, ion channel function, myofibrillogenenous and vesicle trafficking.
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Affiliation(s)
- Anthony J Kee
- Department of Anatomy, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
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Persistent expression of FLAG-tagged micro dystrophin in nonhuman primates following intramuscular and vascular delivery. Mol Ther 2009; 18:109-17. [PMID: 19904237 PMCID: PMC2839222 DOI: 10.1038/mt.2009.254] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Animal models for Duchenne muscular dystrophy (DMD) have species limitations related to assessing function, immune response, and distribution of micro- or mini-dystrophins. Nonhuman primates (NHPs) provide the ideal model to optimize vector delivery across a vascular barrier and provide accurate dose estimates for widespread transduction. To address vascular delivery and dosing in rhesus macaques, we have generated a fusion construct that encodes an eight amino-acid FLAG epitope at the C-terminus of micro-dystrophin to facilitate translational studies targeting DMD. Intramuscular (IM) injection of AAV8.MCK.micro-dys.FLAG in the tibialis anterior (TA) of macaques demonstrated robust gene expression, with muscle transduction (50-79%) persisting for up to 5 months. Success by IM injection was followed by targeted vascular delivery studies using a fluoroscopy-guided catheter threaded through the femoral artery. Three months after gene transfer, >80% of muscle fibers showed gene expression in the targeted muscle. No cellular immune response to AAV8 capsid, micro-dystrophin, or the FLAG tag was detected by interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spot (ELISpot) at any time point with either route. In summary, an epitope-tagged micro-dystrophin cassette enhances the ability to evaluate site-specific localization and distribution of gene expression in the NHP in preparation for vascular delivery clinical trials.
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Jørgensen LH, Larochelle N, Orlopp K, Dunant P, Dudley RW, Stucka R, Thirion C, Walter MC, Laval SH, Lochmüller H. Efficient and Fast Functional Screening of Microdystrophin ConstructsIn VivoandIn Vitrofor Therapy of Duchenne Muscular Dystrophy. Hum Gene Ther 2009; 20:641-50. [DOI: 10.1089/hum.2008.162] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Louise H. Jørgensen
- Institute of Human Genetics, University of Newcastle, Newcastle upon Tyne NE1 3BZ, United Kingdom
| | - Nancy Larochelle
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Kristian Orlopp
- Friedrich Baur Institute and Department of Neurology, Ludwig Maximilians University, Munich 81377, Germany
| | - Patrick Dunant
- Friedrich Baur Institute and Department of Neurology, Ludwig Maximilians University, Munich 81377, Germany
| | - Roy W.R. Dudley
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Rolf Stucka
- Friedrich Baur Institute and Department of Neurology, Ludwig Maximilians University, Munich 81377, Germany
| | - Christian Thirion
- Friedrich Baur Institute and Department of Neurology, Ludwig Maximilians University, Munich 81377, Germany
| | - Maggie C. Walter
- Friedrich Baur Institute and Department of Neurology, Ludwig Maximilians University, Munich 81377, Germany
| | - Steven H. Laval
- Institute of Human Genetics, University of Newcastle, Newcastle upon Tyne NE1 3BZ, United Kingdom
| | - Hanns Lochmüller
- Institute of Human Genetics, University of Newcastle, Newcastle upon Tyne NE1 3BZ, United Kingdom
- Friedrich Baur Institute and Department of Neurology, Ludwig Maximilians University, Munich 81377, Germany
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Papponen H, Kaisto T, Leinonen S, Kaakinen M, Metsikkö K. Evidence for γ-actin as a Z disc component in skeletal myofibers. Exp Cell Res 2009; 315:218-25. [DOI: 10.1016/j.yexcr.2008.10.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Revised: 09/22/2008] [Accepted: 10/11/2008] [Indexed: 11/16/2022]
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Foster H, Sharp PS, Athanasopoulos T, Trollet C, Graham IR, Foster K, Wells DJ, Dickson G. Codon and mRNA Sequence Optimization of Microdystrophin Transgenes Improves Expression and Physiological Outcome in Dystrophic mdx Mice Following AAV2/8 Gene Transfer. Mol Ther 2008; 16:1825-32. [DOI: 10.1038/mt.2008.186] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Odom GL, Gregorevic P, Chamberlain JS. Viral-mediated gene therapy for the muscular dystrophies: successes, limitations and recent advances. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1772:243-62. [PMID: 17064882 PMCID: PMC1894910 DOI: 10.1016/j.bbadis.2006.09.007] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Revised: 09/16/2006] [Accepted: 09/20/2006] [Indexed: 02/07/2023]
Abstract
Much progress has been made over the past decade elucidating the molecular basis for a variety of muscular dystrophies (MDs). Accordingly, there are examples of mouse models of MD whose disease progression has been halted in large part with the use of viral vector technology. Even so, we must acknowledge significant limitations of present vector systems that must be overcome prior to successful treatment of humans with such approaches. This review will present a variety of viral-mediated therapeutic strategies aimed at counteracting the muscle-wasting symptoms associated with muscular dystrophy. We include viral vector systems used for muscle gene transfer, with a particular emphasis on adeno-associated virus. Findings of several encouraging studies focusing on repair of the mutant dystrophin gene are also included. Lastly, we present a discussion of muscle compensatory therapeutics being considered that include pathways involved in the up-regulation of utrophin, promotion of cellular adhesion, enhancement of muscle mass, and antagonism of the inflammatory response. Considering the complexity of the muscular dystrophies, it appears likely that a multilayered approach tailored to a patient sub-group may be warranted in order to effectively contest the progression of this devastating disease.
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Affiliation(s)
- Guy L. Odom
- Department of Neurology Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Washington School of Medicine, 1959 NE Pacific Street, Seattle, WA, 98195-7720, USA
| | - Paul Gregorevic
- Department of Neurology Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Washington School of Medicine, 1959 NE Pacific Street, Seattle, WA, 98195-7720, USA
| | - Jeffrey S. Chamberlain
- Department of Neurology Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Washington School of Medicine, 1959 NE Pacific Street, Seattle, WA, 98195-7720, USA
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31
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Heydemann A, Doherty KR, McNally EM. Genetic modifiers of muscular dystrophy: Implications for therapy. Biochim Biophys Acta Mol Basis Dis 2007; 1772:216-28. [PMID: 16916601 DOI: 10.1016/j.bbadis.2006.06.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Accepted: 06/22/2006] [Indexed: 10/24/2022]
Abstract
The genetic understanding of the muscular dystrophies has advanced considerably in the last two decades. Over 25 different individual genes are now known to produce muscular dystrophy, and many different "private" mutations have been described for each individual muscular dystrophy gene. For the more common forms of muscular dystrophy, phenotypic variability can be explained by precise mutations. However, for many genetic mutations, the presence of the identical mutation is associated with marked phenotypic range that affects muscle function as well as cardiac function. The explanation for phenotype variability in the muscular dystrophies is only now being explored. The availability of genetically engineered animal models has allowed the generation of single mutations on the background of highly inbred strain. Phenotypic variation that is altered by genetic background argues for the presence of genetic modifier loci that can ameliorate or enhance aspects of the dystrophic phenotype. A number of individual genes have been implicated as modifiers of muscular dystrophy by studies in genetically engineered mouse models of muscular dystrophy. The value of these genes and products is that the pathways identified through these experiments may be exploited for therapy.
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Affiliation(s)
- Ahlke Heydemann
- Department of Medicine, Section of Cardiology, The University of Chicago, Chicago, IL 60637, USA
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Duan D. Challenges and opportunities in dystrophin-deficient cardiomyopathy gene therapy. Hum Mol Genet 2006; 15 Spec No 2:R253-61. [PMID: 16987891 PMCID: PMC2581718 DOI: 10.1093/hmg/ddl180] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The last decade has evidenced unprecedented progress in gene therapy of Duchenne and Becker muscular dystrophy (DMD and BMD) skeletal muscle disease. Cardiomyopathy is a leading cause of morbidity and mortality in both patients and carriers of DMD, BMD and X-linked dilated cardiomyopathy. However, there is little advance in heart gene therapy. The gene, the vector, vector delivery, the target tissue and animal models are five fundamental components in developing an effective gene therapy. Intensive effort has been made in optimizing gene transfer vectors and methods. Systemic and/or local delivery of recombinant adeno-associated viral vector have resulted in widespread transduction in the rodent heart. The current challenge is to define other parameters that are essential for a successful gene therapy such as the best candidate gene(s), the optimal expression level and the target tissue. This review focuses on these long-ignored aspects and points out future research directions. In particular, we need to address whether all or only some of the recently developed mini- and microgenes are protective in the heart, whether partial correction can lead to whole heart function improvement, whether over-expression is hazardous and whether correcting skeletal muscle disease can slow down or stop the progression of cardiomyopathy. Discussion is also made on whether the current mouse models can meet these research needs.
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Affiliation(s)
- Dongsheng Duan
- Department of Molecular Microbiology and Immunology, The University of Missouri School of Medicine, One Hospital Dr., Room M610G, MSB Columbia, MO 65212, USA.
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Ervasti JM. Dystrophin, its interactions with other proteins, and implications for muscular dystrophy. Biochim Biophys Acta Mol Basis Dis 2006; 1772:108-17. [PMID: 16829057 DOI: 10.1016/j.bbadis.2006.05.010] [Citation(s) in RCA: 221] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Revised: 05/31/2006] [Accepted: 05/31/2006] [Indexed: 11/27/2022]
Abstract
Duchenne muscular dystrophy is the most prevalent and severe form of human muscular dystrophy. Investigations into the molecular basis for Duchenne muscular dystrophy were greatly facilitated by seminal studies in the 1980s that identified the defective gene and its major protein product, dystrophin. Biochemical studies revealed its tight association with a multi-subunit complex, the so-named dystrophin-glycoprotein complex. Since its description, the dystrophin-glycoprotein complex has emerged as an important structural unit of muscle and also as a critical nexus for understanding a diverse array of muscular dystrophies arising from defects in several distinct genes. The dystrophin homologue utrophin can compensate at the cell/tissue level for dystrophin deficiency, but functions through distinct molecular mechanisms of protein-protein interaction.
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Affiliation(s)
- James M Ervasti
- Department of Physiology, 127 Service Memorial Institute, University of Wisconsin Medical School, 1300 University Avenue, Madison, WI 53706, USA.
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Draviam RA, Wang B, Li J, Xiao X, Watkins SC. Mini-dystrophin efficiently incorporates into the dystrophin protein complex in living cells. J Muscle Res Cell Motil 2006; 27:53-67. [PMID: 16496225 DOI: 10.1007/s10974-006-9055-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Accepted: 01/03/2006] [Indexed: 11/27/2022]
Abstract
Dystrophin is a critical muscle cell structural protein which when deficient results in Duchenne muscular dystrophy. Recently miniature versions of the dystrophin gene have been constructed that ameliorate the pathology in mouse models. To characterize mini-dystrophin's incorporation into the dystrophin protein complex in living cells, two fusion proteins were constructed where mini-dystrophin is fused to the N- or C-terminus of an enhanced green fluorescent protein reporter gene. Both fusion proteins correctly localize at the plasma membrane in vitro and in vivo. Live cell microscopy establishes that mini-dystrophin translocates directly to the PM of differentiating muscle cells, within 4 h of expression. Latrunculin A treatment, actin and beta-dystroglycan binding domain deletion constructs, and co-immunoprecipitation assays demonstrate that mini-dystrophin is firmly anchored to the sarcolemma primarily through its connections to beta-dystroglycan, mimicking effects seen with wild type dystrophin. Furthermore, point mutations made within the putative beta-dystroglycan anchoring ZZ domain of mini-dystrophin result in an ablation of beta-dystroglycan binding and a nuclear translocation of the protein. These results demonstrate that mini-dystrophin is efficiently bound and incorporated into the dystrophin protein complex, via beta-dystroglycan in living cells, similarly to the full length dystrophin protein.
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MESH Headings
- Actins/metabolism
- Active Transport, Cell Nucleus/physiology
- Bridged Bicyclo Compounds, Heterocyclic/pharmacology
- Cell Line
- Cell Membrane/metabolism
- Dystroglycans/metabolism
- Dystrophin/genetics
- Dystrophin/metabolism
- Green Fluorescent Proteins/metabolism
- Humans
- Macromolecular Substances/metabolism
- Molecular Weight
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/ultrastructure
- Muscular Dystrophy, Duchenne/genetics
- Muscular Dystrophy, Duchenne/metabolism
- Muscular Dystrophy, Duchenne/physiopathology
- Protein Binding/physiology
- Protein Structure, Tertiary/physiology
- Protein Transport/physiology
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Sarcolemma/metabolism
- Thiazolidines/pharmacology
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Affiliation(s)
- Romesh A Draviam
- Department of Cell Biology and Molecular Physiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA. romesh@ pitt.edu
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35
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Abstract
Gene therapy for muscular dystrophy represents a promising avenue of pursuit for a disease with a limited repertoire of treatment. Recent successes in the research arena using adeno-associated viral vectors should accelerate the movement of gene-based therapeutics for muscle disorders into the clinic. Nevertheless, significant challenges remain before gene therapy can deliver on the promises avowed by early pioneers of the field. This review examines recent progress and the hurdles remaining to achieve gene-based treatment therapies for muscular dystrophy.
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Affiliation(s)
- Jerry R Mendell
- Center for Gene Therapy, Columbus Children's Research Institute, Columbus, OH 43205, USA.
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36
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Stone MR, O'Neill A, Catino D, Bloch RJ. Specific interaction of the actin-binding domain of dystrophin with intermediate filaments containing keratin 19. Mol Biol Cell 2005; 16:4280-93. [PMID: 16000376 PMCID: PMC1196337 DOI: 10.1091/mbc.e05-02-0112] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Cytokeratins 8 and 19 concentrate at costameres of striated muscle and copurify with the dystrophin-glycoprotein complex, perhaps through the interaction of the cytokeratins with the actin-binding domain of dystrophin. We overexpressed dystrophin's actin-binding domain (Dys-ABD), K8 and K19, as well as closely related proteins, in COS-7 cells to assess the basis and specificity of their interaction. Dys-ABD alone associated with actin microfilaments. Expressed with K8 and K19, which form filaments, Dys-ABD associated preferentially with the cytokeratins. This interaction was specific, as the homologous ABD of betaI-spectrin failed to interact with K8/K19 filaments, and Dys-ABD did not associate with desmin or K8/K18 filaments. Studies in COS-7 cells and in vitro showed that Dys-ABD binds directly and specifically to K19. Expressed in muscle fibers in vivo, K19 accumulated in the myoplasm in structures that contained dystrophin and spectrin and disrupted the organization of the sarcolemma. K8 incorporated into sarcomeres, with no effect on the sarcolemma. Our results show that dystrophin interacts through its ABD with K19 specifically and are consistent with the idea that cytokeratins associate with dystrophin at the sarcolemma of striated muscle.
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Affiliation(s)
- Michele R Stone
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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37
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Liu M, Yue Y, Harper SQ, Grange RW, Chamberlain JS, Duan D. Adeno-associated virus-mediated microdystrophin expression protects young mdx muscle from contraction-induced injury. Mol Ther 2005; 11:245-56. [PMID: 15668136 PMCID: PMC2581717 DOI: 10.1016/j.ymthe.2004.09.013] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2004] [Accepted: 09/01/2004] [Indexed: 11/22/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is the most common inherited lethal muscle degenerative disease. Currently there is no cure. Highly abbreviated microdystrophin cDNAs were developed recently for adeno-associated virus (AAV)-mediated DMD gene therapy. Among these, a C-terminal-truncated DeltaR4-R23/DeltaC microgene (DeltaR4/DeltaC) has been considered as a very promising therapeutic candidate gene. In this study, we packaged a CMV.DeltaR4/DeltaC cassette in AAV-5 and evaluated the transduction and muscle contractile profiles in the extensor digitorum longus muscles of young (7-week-old) and adult (9-month-old) mdx mice. At approximately 3 months post-gene transfer, 50-60% of the total myofibers were transduced in young mdx muscle and the percentage of centrally nucleated myofibers was reduced from approximately 70% in untreated mdx muscle to approximately 22% in microdystrophin-treated muscle. Importantly, this level of transduction protected mdx muscle from eccentric contraction-induced damage. In contrast, adult mdx muscle was more resistant to AAV-5 transduction, as only approximately 30% of the myofibers were transduced at 3 months postinfection. This transduction yielded marginal protection against eccentric contraction-induced injury. The extent of central nucleation was also more difficult to reverse in adult mdx muscle (from approximately 83% in untreated to approximately 58% in treated). Finally, we determined that the DeltaR4/DeltaC microdystrophin did not significantly alter the expression pattern of the endogenous full-length dystrophin in normal muscle. Neither did it have any adverse effects on normal muscle morphology or contractility. Taken together, our results suggest that AAV-mediated DeltaR4/DeltaC microdystrophin expression represents a promising approach to rescue muscular dystrophy in young mdx skeletal muscle.
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Affiliation(s)
- Mingju Liu
- Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, One Hospital Drive, Room M610G, MSB, Columbia, MO 65212, USA
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Athanasopoulos T, Graham IR, Foster H, Dickson G. Recombinant adeno-associated viral (rAAV) vectors as therapeutic tools for Duchenne muscular dystrophy (DMD). Gene Ther 2004; 11 Suppl 1:S109-21. [PMID: 15454965 DOI: 10.1038/sj.gt.3302379] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Duchenne muscular dystrophy (DMD) is a lethal genetic muscle disorder caused by recessive mutations in the dystrophin gene. The size of the gene (2.4 Mb) and mRNA (14 kb) in addition to immunogenicity problems and inefficient transduction of mature myofibres by currently available vector systems are formidable obstacles to the development of efficient gene therapy approaches. Adeno-associated viral (AAV) vectors overcome many of the problems associated with other vector systems (nonpathogenicity and minimal immunogenicity, extensive cell and tissue tropism) but accommodate limited transgene capacity (<5 kb). As a result of these observations, a number of laboratories worldwide have engineered a series of microdystrophin cDNAs based on genotype-phenotype relationship in Duchenne (DMD) and Becker (BMD) dystrophic patients, and transgenic studies in mdx mice. Recent progress in characterization of AAV serotypes from various species has demonstrated that alternative AAV serotypes are far more efficient in transducing muscle than the traditionally used AAV2. This article summarizes the current progress in the field of recombinant adeno-associated viral (rAAV) delivery for DMD, including optimization of recombinant AAV-microdystrophin vector systems/cassettes targeting the skeletal and cardiac musculature.
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Affiliation(s)
- T Athanasopoulos
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, UK
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39
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van Deutekom JCT, van Ommen GJB. Advances in Duchenne muscular dystrophy gene therapy. Nat Rev Genet 2003; 4:774-83. [PMID: 14526374 DOI: 10.1038/nrg1180] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Since the initial characterization of the genetic defect for Duchenne muscular dystrophy, much effort has been expended in attempts to develop a therapy for this devastating childhood disease. Gene therapy was the obvious answer but, initially, the dystrophin gene and its product seemed too large and complex for this approach. However, our increasing knowledge of the organization of the gene and the role of dystrophin in muscle function has indicated ways to manipulate them both. Gene therapy for Duchenne muscular dystrophy now seems to be in reach.
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Affiliation(s)
- Judith C T van Deutekom
- Center for Human and Clinical Genetics, Leiden University Medical Center, Wassenaarseweg 72, 2333 AL Leiden, The Netherlands.
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Dunant P, Larochelle N, Thirion C, Stucka R, Ursu D, Petrof BJ, Wolf E, Lochmüller H. Expression of dystrophin driven by the 1.35-kb MCK promoter ameliorates muscular dystrophy in fast, but not in slow muscles of transgenic mdx mice. Mol Ther 2003; 8:80-9. [PMID: 12842431 DOI: 10.1016/s1525-0016(03)00129-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Successful gene therapy of Duchenne muscular dystrophy may require the lifelong expression of a therapeutic gene in all affected muscles. The most promising gene delivery vehicles, viral vectors, suffer from several limitations, including immunogenicity, loss of therapeutic gene expression, and a limited packaging capacity. Therefore, various efforts were previously undertaken to use small therapeutic genes and to place them under the control of a strong and muscle-specific promoter. Here we report the effects of a minidystrophin (6.3 kb) under the control of a short muscle-specific promoter (MCK 1.35 kb) over most of the lifetime (4-20 months) of a transgenic mouse model. Dystrophin expression remained stable and muscle-specific at all ages. The dystrophic phenotype was greatly ameliorated and, most importantly, muscle function in limb muscles was significantly improved not only in young adult but also in aged mice compared to nontransgenic littermates. Dystrophin expression was strong in fast-twitch skeletal muscles such as tibialis anterior and extensor digitorum longus, but weak or absent in heart, diaphragm, and slow-twitch muscles. Additionally, expression was strong in glycolytic but weak in oxidative fibers of fast-twitch muscles. This study may have important implications for the design of future gene therapy trials for muscular dystrophy.
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Affiliation(s)
- Patrick Dunant
- Gene Center, Friedrich-Baur-Institute, and Department of Neurology, Ludwig-Maximilians University, 81377, Munich, Germany
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41
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Wells DJ, Wells KE. Gene transfer studies in animals: what do they really tell us about the prospects for gene therapy in DMD? Neuromuscul Disord 2002; 12 Suppl 1:S11-22. [PMID: 12206790 DOI: 10.1016/s0960-8966(02)00077-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
There is a pressing need to develop new therapeutic approaches to Duchenne muscular dystrophy, an X-linked fatal disease primarily affecting skeletal and cardiac muscle. Gene therapy is an approach that has attracted much interest since the description of the Duchenne muscular dystrophy gene and its mutations in 1987. Since 1990 numerous reporter and dystrophin gene transfer studies have been conducted on muscles of animals but mostly in mice. Experimental protocols have ranged from germ-line gene transfer (via the production of transgenics) to somatic gene transfer studies using viral or non-viral vectors. But what have we actually learned from such studies that can be applied to patients with Duchenne muscular dystrophy? Various dystrophin, utrophin and integrin recombinant cDNAs have been shown to prevent the development of muscular dystrophy in transgenic dystrophic (mdx) mice. Somatic gene transfer prior to the onset of pathology have been shown to prevent the development of the muscular dystrophy in the mdx mouse but the data is less convincing for the beneficial effects of somatic gene transfer following the establishment of pathology. The time of onset and the course of the disease differ substantially between mouse and man and raise concerns about the applicability of gene therapy in man where the disease manifests in utero and the progression is more severe. The other major concern relates to uncertainty over the efficiency of the different vectors in man, particularly as many patients are likely to have encountered the infectious forms of the viruses that are proposed as vectors.
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Affiliation(s)
- Dominic J Wells
- Gene Targeting Unit, Department of Neuromuscular Diseases, Division of Neuroscience and Psychological Medicine, Faculty of Medicine, Imperial College, Charing Cross Campus, St. Dunstan's Road, London W6 8RP, UK.
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Dickson G, Roberts ML, Wells DJ, Fabb SA. Recombinant micro-genes and dystrophin viral vectors. Neuromuscul Disord 2002; 12 Suppl 1:S40-4. [PMID: 12206793 DOI: 10.1016/s0960-8966(02)00080-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
An effective gene therapy for Duchenne muscular dystrophy ideally relies on the ability to provide long-term expression to muscle tissue of the missing protein, dystrophin. Early work in the mdx mouse using a 6.3 kb mini-dystrophin cDNA, carried out in either adenoviral or retroviral vectors was generally successful, however, expression was only transient. In an attempt to remedy this problem, two approaches are being investigated. The first of these is a hybrid vector system that combines the efficacy of gene transfer into skeletal muscle of adenoviral vectors with the long-term stability of retroviral vectors. The second utilises the inherently efficient transducing properties and stability of the adeno-associated viral delivery system. Using highly truncated micro-dystrophin cDNAs we have shown that both vector systems were able to restore dystrophin and dystrophin-associated protein expression at the plasma membrane of mdx mice for prolonged periods of time. Additionally, evaluation of central nucleation indicated a significant inhibition of degenerative dystrophic muscle pathology. These studies suggest that hybrid adenoviral-retroviral and adeno-associated viral vectors are capable of ameliorating dystrophic pathology at the cellular level and as such are useful tools in the development of a gene therapy for Duchenne muscular dystrophy.
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Affiliation(s)
- G Dickson
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway, University of London, Surrey TW20 0EX, UK.
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43
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Scott JM, Li S, Harper SQ, Welikson R, Bourque D, DelloRusso C, Hauschka SD, Chamberlain JS. Viral vectors for gene transfer of micro-, mini-, or full-length dystrophin. Neuromuscul Disord 2002; 12 Suppl 1:S23-9. [PMID: 12206791 DOI: 10.1016/s0960-8966(02)00078-0] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Gene therapy for Duchenne muscular dystrophy will require methods to deliver gene constructs encoding functional versions of dystrophin to the vast majority of a patient's musculature. Obstacles to achieving these goals include identifying which forms of dystrophin would be effective in a clinical setting and developing gene delivery shuttles capable of carrying and expressing dystrophin cassettes without toxic or adverse immunologic consequences. We review here recent work from our laboratory to identify sequences within dystrophin that are required to prevent development of dystrophic changes in muscle or which might be able to correct pre-existing damage. We also describe work aimed at developing viral shuttle vectors able to carry and express these dystrophin cassettes at high levels and in a muscle-specific fashion. While great challenges remain in developing methods for systemic gene delivery, we show that a variety of viral vectors are able to carry and express therapeutic levels of dystrophin when delivered directly to mouse skeletal muscle.
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Affiliation(s)
- Jeannine M Scott
- Department of Neurology, University of Washington School of Medicine, Seattle, WA 98195, USA
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44
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Watchko JF, O'Day TL, Hoffman EP. Functional characteristics of dystrophic skeletal muscle: insights from animal models. J Appl Physiol (1985) 2002; 93:407-17. [PMID: 12133845 DOI: 10.1152/japplphysiol.01242.2001] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Muscular dystrophies are a clinically and genetically heterogeneous group of disorders that show myofiber degeneration and regeneration. Identification of animal models of muscular dystrophy has been instrumental in research on the pathogenesis, pathophysiology, and treatment of these disorders. We review our understanding of the functional status of dystrophic skeletal muscle from selected animal models with a focus on 1) the mdx mouse model of Duchenne muscular dystrophy, 2) the Bio 14.6 delta-sarcoglycan-deficient hamster model of limb-girdle muscular dystrophy, and 3) transgenic null mutant murine lines of sarcoglycan (alpha, beta, delta, and gamma) deficiencies. Although biochemical data from these models suggest that the dystrophin-sarcoglycan-dystroglycan-laminin network is critical for structural integrity of the myofiber plasma membrane, emerging studies of muscle physiology suggest a more complex picture, with specific functional deficits varying considerably from muscle to muscle and model to model. It is likely that changes in muscle structure and function, downstream of the specific, primary biochemical deficiency, may alter muscle contractile properties.
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Affiliation(s)
- Jon F Watchko
- Department of Pediatrics, Magee-Women's Research Institute, Duchenne Muscular Dystrophy Research Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
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Crosbie RH, Dovico SA, Flanagan JD, Chamberlain JS, Ownby CL, Campbell KP. Characterization of aquaporin-4 in muscle and muscular dystrophy. FASEB J 2002; 16:943-9. [PMID: 12087055 DOI: 10.1096/fj.01-0327com] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Aquaporins are a growing family of transmembrane proteins that transport water and, in some cases, glycerol and urea across cellular membranes. Aquaporin-4 (AQP4) is enriched at the sarcolemma of skeletal muscle and may play a role in accommodating the rapid changes in cell volume and hydrostatic forces that occur during contraction in order to prevent damage to the sarcolemma. Recent evidence has shown that AQP4 is absent in dystrophin-deficient mdx mice, suggesting that AQP4 associates with dystrophin and has a role in the dystrophic process. To examine the relationship between aquaporins and muscle disease, and between aquaporins and dystrophin, we have investigated aquaporin expression in various mouse models of muscular dystrophy and cardiomyopathy before and after the onset of pathology. We find that AQP4 is expressed in prenecrotic mdx muscle despite the absence of dystrophin and that AQP4 is lost after the onset of muscle degeneration. Analysis of various dystrophin transgenic mice reveals that AQP4 is lost even when the dystrophin-glycoprotein complex is present, suggesting that loss of AQP4 is not directly resulting from loss of the DGC. AQP4 was also lost in muscular dystrophies caused by primary mutations in the sarcoglycan genes. Taken together, our data demonstrate that AQP4 loss in skeletal muscle correlates with muscular dystrophy and is a common feature of pathogenesis.
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Affiliation(s)
- Rachelle H Crosbie
- Howard Hughes Medical Institute, Department of Physiology and Biophysics, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA
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Abstract
Muscular dystrophies are associated with mutations in genes encoding several classes of proteins. These range from extracellular matrix and integral membrane proteins to cytoskeletal proteins, but also include a heterogeneous group of proteins including proteases, nuclear proteins, and signalling molecules. Muscular dystrophy phenotypes have also become evident in studies on various knockout mice defective in proteins not previously considered or known to be mutated in muscular dystrophies. Some unifying themes are beginning to emerge from all of these data. This review will consider recent advances in our understanding of the molecules involved and bring together data that suggest a role for the cytoskeleton and cell adhesion in muscular dystrophies.
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Affiliation(s)
- Heather J Spence
- Institute of Biological and Life Sciences, Glasgow Cell Biology Group, Scotland
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Harper SQ, Hauser MA, DelloRusso C, Duan D, Crawford RW, Phelps SF, Harper HA, Robinson AS, Engelhardt JF, Brooks SV, Chamberlain JS. Modular flexibility of dystrophin: implications for gene therapy of Duchenne muscular dystrophy. Nat Med 2002; 8:253-61. [PMID: 11875496 DOI: 10.1038/nm0302-253] [Citation(s) in RCA: 412] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Attempts to develop gene therapy for Duchenne muscular dystrophy (DMD) have been complicated by the enormous size of the dystrophin gene. We have performed a detailed functional analysis of dystrophin structural domains and show that multiple regions of the protein can be deleted in various combinations to generate highly functional mini- and micro-dystrophins. Studies in transgenic mdx mice, a model for DMD, reveal that a wide variety of functional characteristics of dystrophy are prevented by some of these truncated dystrophins. Muscles expressing the smallest dystrophins are fully protected against damage caused by muscle activity and are not morphologically different from normal muscle. Moreover, injection of adeno-associated viruses carrying micro-dystrophins into dystrophic muscles of immunocompetent mdx mice results in a striking reversal of histopathological features of this disease. These results demonstrate that the dystrophic pathology can be both prevented and reversed by gene therapy using micro-dystrophins.
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Affiliation(s)
- Scott Q Harper
- Department of Neurology, University of Washington School of Medicine, Seattle, Washington, USA
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Hara H, Nolan PM, Scott MO, Bucan M, Wakayama Y, Fischbeck KH. Running endurance abnormality in mdx mice. Muscle Nerve 2002; 25:207-11. [PMID: 11870688 DOI: 10.1002/mus.10023] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The mdx mouse lacks dystrophin and has histological features of Duchenne muscular dystrophy but little weakness in the first year of life. We report here an early deficit in voluntary wheel running, as assayed with a computerized wheel. All mdx mice showed an intermittent running pattern, in contrast to the continuous running seen in controls. The average continuous running time differed significantly between mdx and control mice at all ages tested (5-21 weeks). This assay is noninvasive, has the advantage of unbiased automatic data collection, and should be useful for quantifying the mdx deficit in therapeutic studies.
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Affiliation(s)
- Hajime Hara
- Division of Neurology, Department of Medicine, Showa University, Fujigaoka Hospital, 1-30, Fujigaoka, Aobaku, Yokohamashi 227-0043, Japan.
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Rando TA. The dystrophin-glycoprotein complex, cellular signaling, and the regulation of cell survival in the muscular dystrophies. Muscle Nerve 2001; 24:1575-94. [PMID: 11745966 DOI: 10.1002/mus.1192] [Citation(s) in RCA: 281] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mutations of different components of the dystrophin-glycoprotein complex (DGC) cause muscular dystrophies that vary in terms of severity, age of onset, and selective involvement of muscle groups. Although the primary pathogenetic processes in the muscular dystrophies have clearly been identified as apoptotic and necrotic muscle cell death, the pathogenetic mechanisms that lead to cell death remain to be determined. Studies of components of the DGC in muscle and in nonmuscle tissues have revealed that the DGC is undoubtedly a multifunctional complex and a highly dynamic structure, in contrast to the unidimensional concept of the DGC as a mechanical component in the cell. Analysis of the DGC reveals compelling analogies to two other membrane-associated protein complexes, namely integrins and caveolins. Each of these complexes mediates signal transduction cascades in the cell, and disruption of each complex causes muscular dystrophies. The signal transduction cascades associated with the DGC, like those associated with integrins and caveolins, play important roles in cell survival signaling, cellular defense mechanisms, and regulation of the balance between cell survival and cell death. This review focuses on the functional components of the DGC, highlighting the evidence of their participation in cellular signaling processes important for cell survival. Elucidating the link between these functional components and the pathogenetic processes leading to cell death is the foremost challenge to understanding the mechanisms of disease expression in the muscular dystrophies due to defects in the DGC.
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Affiliation(s)
- T A Rando
- Department of Neurology and Neurological Sciences, Stanford University Medical Center, Room A-343, Stanford, California 94305-5235, USA.
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Wang B, Li J, Xiao X. Adeno-associated virus vector carrying human minidystrophin genes effectively ameliorates muscular dystrophy in mdx mouse model. Proc Natl Acad Sci U S A 2000; 97:13714-9. [PMID: 11095710 PMCID: PMC17641 DOI: 10.1073/pnas.240335297] [Citation(s) in RCA: 329] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is the most common and lethal genetic muscle disorder, caused by recessive mutations in the dystrophin gene. One of every 3,500 males suffers from DMD, yet no treatment is currently available. Genetic therapeutic approaches, using primarily myoblast transplantation and adenovirus-mediated gene transfer, have met with limited success. Adeno-associated virus (AAV) vectors, although proven superior for muscle gene transfer, are too small (5 kb) to package the 14-kb dystrophin cDNA. Here we have created a series of minidystrophin genes (<4.2 kb) under the control of a muscle-specific promoter that readily package into AAV vectors. When injected into the muscle of mdx mice (a DMD model), two of the minigenes resulted in efficient and stable expression in a majority of the myofibers, restoring the missing dystrophin and dystrophin-associated protein complexes onto the plasma membrane. More importantly, this AAV treatment ameliorated dystrophic pathology in mdx muscle and led to normal myofiber morphology, histology, and cell membrane integrity. Thus, we have defined minimal functional dystrophin units and demonstrated the effectiveness of using AAV to deliver the minigenes in vivo, offering a promising avenue for DMD gene therapy.
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Affiliation(s)
- B Wang
- Department of Molecular Genetics and Biochemistry, Gene Therapy Center, and Duchenne Muscular Dystrophy Research Center and Department of Orthopedic Surgery, University of Pittsburgh, Pittsburgh, PA 15261, USA
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