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Progress in Retinal and Eye Research Jul 2023Duchenne muscular dystrophy (DMD) is caused by X-linked inherited or de novo DMD gene mutations predominantly affecting males who develop early-onset muscle... (Review)
Review
Duchenne muscular dystrophy (DMD) is caused by X-linked inherited or de novo DMD gene mutations predominantly affecting males who develop early-onset muscle degeneration, severely affecting their quality of life and leading to reduced life expectancy. DMD patients may also develop proliferative retinopathy, cataract, ERG abnormalities, altered contrast sensitivity, color vision losses, and elevated flash detection thresholds during dark adaptation. Depending on the position of the genetic alteration in the large DMD gene, it is associated with a lack of the full-length dystrophin protein possibly with an additional loss of one or several other dystrophins, which are normally transcribed from internal promoters in retina and crystalline lens. During the last decades, the properties of the dystrophins have been characterized in patients with different genetic alterations and in genetic mouse models of DMD. The complex expression pattern of the dystrophins in photoreceptors, Müller glial cells and astrocytes, likely influences synaptic transmission, ionic balance and vascular integrity of the retina. However, the specific function of each retinal dystrophin remains largely unknown. This review describes the current knowledge on dystrophin expression, the putative molecular, structural, and physiological properties of retinal dystrophins, and the main clinical implications associated with the loss of dystrophins in DMD patients and mouse models. Current data and working hypotheses warrant future research on retinal dystrophins to increase our understanding of dystrophin function in the central nervous system in general and to unveil new retinal mechanisms and therapeutic avenues for retinal diseases.
Topics: Male; Mice; Animals; Dystrophin; Muscular Dystrophy, Duchenne; Quality of Life; Retina; Retinal Diseases
PubMed: 36404230
DOI: 10.1016/j.preteyeres.2022.101137 -
Cellular Oncology (Dordrecht) Feb 2021Mutation of the Duchenne muscular dystrophy (DMD) gene causes Duchenne and Becker muscular dystrophy, degenerative neuromuscular disorders that primarily affect... (Review)
Review
BACKGROUND
Mutation of the Duchenne muscular dystrophy (DMD) gene causes Duchenne and Becker muscular dystrophy, degenerative neuromuscular disorders that primarily affect voluntary muscles. However, increasing evidence implicates DMD in the development of all major cancer types. DMD is a large gene with 79 exons that codes for the essential muscle protein dystrophin. Alternative promotor usage drives the production of several additional dystrophin protein products with roles that extend beyond skeletal muscle. The importance and function(s) of these gene products outside of muscle are not well understood.
CONCLUSIONS
We highlight a clear role for DMD in the pathogenesis of several cancers, including sarcomas, leukaemia's, lymphomas, nervous system tumours, melanomas and various carcinomas. We note that the normal balance of DMD gene products is often disrupted in cancer. The short dystrophin protein Dp71 is, for example, typically maintained in cancer whilst the full-length Dp427 gene product, a likely tumour suppressor, is frequently inactivated in cancer due to a recurrent loss of 5' exons. Therefore, the ratio of short and long gene products may be important in tumorigenesis. In this review, we summarise the tumours in which DMD is implicated and provide a hypothesis for possible mechanisms of tumorigenesis, although the question of cause or effect may remain. We hope to stimulate further study into the potential role of DMD gene products in cancer and the development of novel therapeutics that target DMD.
Topics: Animals; Dystrophin; Genetic Predisposition to Disease; Humans; Models, Biological; Muscular Dystrophy, Duchenne; Neoplasms
PubMed: 33188621
DOI: 10.1007/s13402-020-00572-y -
Neuroscience Letters Mar 2020The Dystrophin Glycoprotein Complex (DGC) is a large multi-protein complex that links cytoskeleton actin to the extracellular matrix. This complex is critical in... (Review)
Review
The Dystrophin Glycoprotein Complex (DGC) is a large multi-protein complex that links cytoskeleton actin to the extracellular matrix. This complex is critical in maintaining the structural integrity of muscle fibers and the stability of the neuromuscular synapse. The DGC consists of dystrophin and its utrophin homolog, as well as dystroglycans, sarcoglycans, sarcospan, syntrophins, and dystrobrevins. Deficiencies in DGC proteins result in several forms of muscular dystrophy with varying symptoms and degrees of severity in addition to structurally abnormal neuromuscular junctions (NMJs). This mini-review highlights current knowledge regarding the role of the DGC on the molecular dynamics of acetylcholine receptors (AChRs) as it relates to the formation and maintenance of the mammalian NMJ.
Topics: Animals; Dystrophin; Glycoproteins; Humans; Neuromuscular Junction; Receptors, Cholinergic
PubMed: 32057921
DOI: 10.1016/j.neulet.2020.134833 -
Human Gene Therapy May 2023Muscular dystrophies (MDs) comprise a diverse group of inherited disorders characterized by progressive muscle loss and weakness. Given the genetic etiology underlying... (Review)
Review
Muscular dystrophies (MDs) comprise a diverse group of inherited disorders characterized by progressive muscle loss and weakness. Given the genetic etiology underlying MDs, researchers have explored the potential of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) genome editing as a therapeutic intervention, resulting in significant advances. Here, we review recent progress on the use of CRISPR/Cas9 genome editing as a potential therapy for MDs. Significant strides have been made in this realm, made possible through innovative techniques such as precision genetic editing by modified forms of CRISPR/Cas9. These approaches have shown varying degrees of success in animal models of MD, including Duchenne MD, congenital muscular dystrophy type 1A, and myotonic dystrophy type 1. Even so, there are several challenges facing the development of CRISPR/Cas9-based MD therapies, including the targeting of satellite cells, improved editing efficiency in skeletal and cardiac muscle tissue, delivery vehicle enhancements, and the host immunogenic response. Although more work is needed to advance CRISPR/Cas9 genome editing past the preclinical stages, its therapeutic potential for MD is extremely promising and justifies concentrated efforts to move into clinical trials.
Topics: Animals; Gene Editing; CRISPR-Cas Systems; Muscular Dystrophy, Duchenne; Genetic Therapy; Dystrophin
PubMed: 37119122
DOI: 10.1089/hum.2023.059 -
Methods in Molecular Biology (Clifton,... 2023Duchenne muscular dystrophy (DMD) is a fatal neuromuscular disorder, caused by mutations in the DMD gene coding dystrophin. Applying clustered regularly interspaced...
Duchenne muscular dystrophy (DMD) is a fatal neuromuscular disorder, caused by mutations in the DMD gene coding dystrophin. Applying clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated proteins (CRISPR-Cas) for therapeutic gene editing represents a promising technology to correct this devastating disease through elimination of underlying genetic mutations. Adeno-associated virus (AAV) has been widely used for gene therapy due to its low immunogenicity and high tissue tropism. In particular, CRISPR-Cas9 gene editing components packaged by self-complementary AAV (scAAV) demonstrate robust viral transduction and efficient gene editing, enabling restoration of dystrophin expression throughout skeletal and cardiac muscle in animal models of DMD. Here, we describe protocols for cloning CRISPR single guide RNAs (sgRNAs) into a scAAV plasmid and procedures for systemic delivery of AAVs into a DMD mouse model. We also provide methodologies for quantification of dystrophin restoration after systemic CRISPR-Cas9-mediated correction of DMD.
Topics: Mice; Animals; Dystrophin; Muscular Dystrophy, Duchenne; Dependovirus; CRISPR-Cas Systems; Exons; Muscle, Skeletal
PubMed: 36401041
DOI: 10.1007/978-1-0716-2772-3_21 -
Experimental Cell Research Nov 2021Muscular dystrophies are a heterogeneous group of monogenic neuromuscular disorders which lead to progressive muscle loss and degeneration of the musculoskeletal system....
Muscular dystrophies are a heterogeneous group of monogenic neuromuscular disorders which lead to progressive muscle loss and degeneration of the musculoskeletal system. The genetic causes of muscular dystrophies are well characterized, but no effective treatments have been developed so far. The discovery and application of the CRISPR/Cas system for genome editing offers a new path for disease treatment with the potential to permanently correct genetic mutations. The post-mitotic and multinucleated features of skeletal muscle provide an ideal target for CRISPR/Cas therapeutic genome editing because correction of a subpopulation of nuclei can provide benefit to the whole myofiber. In this review, we provide an overview of the CRISPR/Cas system and its derivatives in genome editing, proposing potential CRISPR/Cas-based therapies to correct diverse muscular dystrophies, and we discuss challenges for translating CRISPR/Cas genome editing to a viable therapy for permanent correction of muscular dystrophies.
Topics: Animals; CRISPR-Cas Systems; Disease Models, Animal; Dystrophin; Gene Editing; Genetic Therapy; Humans; Muscular Dystrophy, Duchenne; Mutation
PubMed: 34571006
DOI: 10.1016/j.yexcr.2021.112844 -
Neuropathology and Applied Neurobiology Apr 2022Dystrophin, the protein product of the DMD gene, plays a critical role in muscle integrity by stabilising the sarcolemma during contraction and relaxation. The DMD gene...
AIMS
Dystrophin, the protein product of the DMD gene, plays a critical role in muscle integrity by stabilising the sarcolemma during contraction and relaxation. The DMD gene is vulnerable to a variety of mutations that may cause complete loss, depletion or truncation of the protein, leading to Duchenne and Becker muscular dystrophies. Precise and reproducible dystrophin quantification is essential in characterising DMD mutations and evaluating the outcome of efforts to induce dystrophin through gene therapies. Immunofluorescence microscopy offers high sensitivity to low levels of protein expression along with confirmation of localisation, making it a critical component of quantitative dystrophin expression assays.
METHODS
We have developed an automated and unbiased approach for precise quantification of dystrophin immunofluorescence in muscle sections. This methodology uses microscope images of whole-tissue sections stained for dystrophin and spectrin to measure dystrophin intensity and the proportion of dystrophin-positive coverage at the sarcolemma of each muscle fibre. To ensure objectivity, the thresholds for dystrophin and spectrin are derived empirically from non-sarcolemmal signal intensity within each tissue section. Furthermore, this approach is readily adaptable for measuring fibre morphology and other tissue markers.
RESULTS
Our method demonstrates the sensitivity and reproducibility of this quantification approach across a wide range of dystrophin expression in both dystrophinopathy patient and healthy control samples, with high inter-operator concordance.
CONCLUSION
As efforts to restore dystrophin expression in dystrophic muscle bring new potential therapies into clinical trials, this methodology represents a valuable tool for efficient and precise analysis of dystrophin and other muscle markers that reflect treatment efficacy.
Topics: Biopsy; Dystrophin; Fluorescent Antibody Technique; Humans; Muscle Fibers, Skeletal; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Reproducibility of Results
PubMed: 34847621
DOI: 10.1111/nan.12785 -
Orphanet Journal of Rare Diseases Aug 2022Duchenne muscular dystrophy (DMD) is a clinically common X-linked recessive myopathy, which is caused by mutation of the gene encoding dystrophin on chromosome Xp21. The... (Review)
Review
Duchenne muscular dystrophy (DMD) is a clinically common X-linked recessive myopathy, which is caused by mutation of the gene encoding dystrophin on chromosome Xp21. The onset of heart injury in children with DMD is inconspicuous, and the prognosis is poor once it develops to the stage of heart failure. Cardiovascular complications remain an important cause of death in this patient population. At present, population and animal studies have suggested that Electrocardiogram (ECG) changes may be the initial manifestation of cardiac involvement in children with DMD. Relevant clinical studies have also confirmed that significant abnormal ECG changes already exist in DMD patients before cardiomegaly and/or LVEF decrease. With increases in age and decreases in cardiac function, the proportion of ECG abnormalities in DMD patients increase significantly. Some characteristic ECG changes, such as ST-segment changes, T wave inversion, Q wave at the inferolateral leads, LBBB and SDANN, have a certain correlation with the indexes of cardiac remodeling or impaired cardiac function in DMD patients, while VT and LBBB have demonstrated relatively good predictive value for the occurrence of long-term DCM and/or adverse cardiovascular events or even death in DMD patients. The present review discusses the electrocardiographic features in children with DMD.
Topics: Animals; Dystrophin; Electrocardiography; Heart; Heart Diseases; Humans; Muscular Dystrophy, Duchenne
PubMed: 35987773
DOI: 10.1186/s13023-022-02473-9 -
Gene Therapy Nov 2022Duchenne muscular dystrophy (DMD) is a lethal, degenerative muscle disorder caused by mutations in the DMD gene, leading to severe reduction or absence of the protein...
Duchenne muscular dystrophy (DMD) is a lethal, degenerative muscle disorder caused by mutations in the DMD gene, leading to severe reduction or absence of the protein dystrophin. Gene therapy strategies that aim to increase expression of a functional dystrophin protein (mini-dystrophin) are under investigation. The ability to accurately quantify dystrophin/mini-dystrophin is essential in assessing the level of gene transduction. We demonstrated the validation and application of a novel peptide immunoaffinity liquid chromatography-tandem mass spectrometry (IA-LC-MS/MS) assay. Data showed that dystrophin expression in Becker muscular dystrophy and DMD tissues, normalized against the mean of non-dystrophic control tissues (n = 20), was 4-84.5% (mean 32%, n = 20) and 0.4-24.1% (mean 5%, n = 20), respectively. In a DMD rat model, biceps femoris tissue from dystrophin-deficient rats treated with AAV9.hCK.Hopti-Dys3978.spA, an adeno-associated virus vector containing a mini-dystrophin transgene, showed a dose-dependent increase in mini-dystrophin expression at 6 months post-dose, exceeding wildtype dystrophin levels at high doses. Validation data showed that inter- and intra-assay precision were ≤20% (≤25% at the lower limit of quantification [LLOQ]) and inter- and intra-run relative error was within ±20% (±25% at LLOQ). IA-LC-MS/MS accurately quantifies dystrophin/mini-dystrophin in human and preclinical species with sufficient sensitivity for immediate application in preclinical/clinical trials.
Topics: Humans; Rats; Animals; Dystrophin; Muscular Dystrophy, Duchenne; Chromatography, Liquid; Tandem Mass Spectrometry; Muscle, Skeletal; Genetic Therapy
PubMed: 34737451
DOI: 10.1038/s41434-021-00300-7 -
PloS One 2023Duchenne muscular dystrophy (DMD) is caused by genetic mutations leading to lack of dystrophin in skeletal muscle. A better understanding of how objective biomarkers for...
Duchenne muscular dystrophy (DMD) is caused by genetic mutations leading to lack of dystrophin in skeletal muscle. A better understanding of how objective biomarkers for DMD vary across subjects and over time is needed to model disease progression and response to therapy more effectively, both in pre-clinical and clinical research. We present an in-depth characterization of disease progression in 3 murine models of DMD by multiomic analysis of longitudinal trajectories between 6 and 30 weeks of age. Integration of RNA-seq, mass spectrometry-based metabolomic and lipidomic data obtained in muscle and blood samples by Multi-Omics Factor Analysis (MOFA) led to the identification of 8 latent factors that explained 78.8% of the variance in the multiomic dataset. Latent factors could discriminate dystrophic and healthy mice, as well as different time-points. MOFA enabled to connect the gene expression signature in dystrophic muscles, characterized by pro-fibrotic and energy metabolism alterations, to inflammation and lipid signatures in blood. Our results show that omic observations in blood can be directly related to skeletal muscle pathology in dystrophic muscle.
Topics: Mice; Animals; Dystrophin; Mice, Inbred mdx; Multiomics; Muscular Dystrophy, Duchenne; Muscle, Skeletal; Disease Progression; Disease Models, Animal
PubMed: 37000843
DOI: 10.1371/journal.pone.0283869