A mutation-independent approach for muscular dystrophy via upregulation of a modifier gene

Neuromuscular disorders are often caused by heterogeneous mutations in large, structurally complex genes. Targeting compensatory modifier genes could be beneficial to improve disease phenotypes. Here we report a mutation-independent strategy to upregulate the expression of a disease-modifying gene a...

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Published in:	Nature (London) Vol. 572; no. 7767; pp. 125 - 130
Main Authors:	Kemaladewi, Dwi U., Bassi, Prabhpreet S., Erwood, Steven, Al-Basha, Dhekra, Gawlik, Kinga I., Lindsay, Kyle, Hyatt, Elzbieta, Kember, Rebekah, Place, Kara M., Marks, Ryan M., Durbeej, Madeleine, Prescott, Steven A., Ivakine, Evgueni A., Cohn, Ronald D.
Format:	Journal Article
Language:	English
Published:	London Nature Publishing Group UK 01-08-2019 Nature Publishing Group
Subjects:	13/106 13/109 13/44 13/51 14 14/1 14/63 42 631/208/199 631/208/737 64 64/60 Analysis Animal models Animals Basic Medicine Care and treatment Congenital diseases CRISPR CRISPR-Associated Protein 9 - genetics CRISPR-Associated Protein 9 - metabolism CRISPR-Cas Systems Deoxyribonucleic acid Disease Disease Progression Disorders DNA Dystrophy Epigenetics Female Fibrosis Fibrosis - metabolism Fibrosis - pathology Gene Editing Gene expression Gene mutations Gene therapy Genes Genes, Modifier - genetics Genetic Therapy - methods Genomes Humanities and Social Sciences Laminin Laminin - genetics Laminin - metabolism Letter Male Medical and Health Sciences Medical Genetics Medicin och hälsovetenskap Medicinsk genetik Medicinska och farmaceutiska grundvetenskaper Methods Mice multidisciplinary Muscle, Skeletal - metabolism Muscle, Skeletal - pathology Muscles Muscular Dystrophies - genetics Muscular Dystrophies - therapy Muscular dystrophy Musculoskeletal system Mutation Myelination Nervous system Neuromuscular diseases Packaging Paralysis Peripheral nerves Phenotypes Polyamines Proteins Rodents Science Science (multidisciplinary) Signs and symptoms Skeletal muscle Up-Regulation Viruses Canada United States > US
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Summary:	Neuromuscular disorders are often caused by heterogeneous mutations in large, structurally complex genes. Targeting compensatory modifier genes could be beneficial to improve disease phenotypes. Here we report a mutation-independent strategy to upregulate the expression of a disease-modifying gene associated with congenital muscular dystrophy type 1A (MDC1A) using the CRISPR activation system in mice. MDC1A is caused by mutations in LAMA2 that lead to nonfunctional laminin-α2, which compromises the stability of muscle fibres and the myelination of peripheral nerves. Transgenic overexpression of Lama1 , which encodes a structurally similar protein called laminin-α1, ameliorates muscle wasting and paralysis in mouse models of MDC1A, demonstrating its importance as a compensatory modifier of the disease 1 . However, postnatal upregulation of Lama1 is hampered by its large size, which exceeds the packaging capacity of vehicles that are clinically relevant for gene therapy. We modulate expression of Lama1 in the dy 2j /dy 2j mouse model of MDC1A using an adeno-associated virus (AAV9) carrying a catalytically inactive Cas9 (dCas9), VP64 transactivators and single-guide RNAs that target the Lama1 promoter. When pre-symptomatic mice were treated, Lama1 was upregulated in skeletal muscles and peripheral nerves, which prevented muscle fibrosis and paralysis. However, for many disorders it is important to investigate the therapeutic window and reversibility of symptoms. In muscular dystrophies, it has been hypothesized that fibrotic changes in skeletal muscle are irreversible. However, we show that dystrophic features and disease progression were improved and reversed when the treatment was initiated in symptomatic dy 2j /dy 2j mice with apparent hindlimb paralysis and muscle fibrosis. Collectively, our data demonstrate the feasibility and therapeutic benefit of CRISPR–dCas9-mediated upregulation of Lama1 , which may enable mutation-independent treatment for all patients with MDC1A. This approach has a broad applicability to a variety of disease-modifying genes and could serve as a therapeutic strategy for many inherited and acquired diseases. When Lama1 was upregulated using CRISPR and a catalytically inactive Cas9 in a mouse model of congenital muscular dystrophy type 1A, apparent hindlimb paralysis, muscle fibrosis and nerve myelination defects were ameliorated in symptomatic mice.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0028-0836 1476-4687
DOI:	10.1038/s41586-019-1430-x