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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 -
Cells Mar 2024Duchenne muscular dystrophy (DMD) is a genetic progressive muscle-wasting disorder that leads to rapid loss of mobility and premature death. The absence of functional... (Review)
Review
Duchenne muscular dystrophy (DMD) is a genetic progressive muscle-wasting disorder that leads to rapid loss of mobility and premature death. The absence of functional dystrophin in DMD patients reduces sarcolemma stiffness and increases contraction damage, triggering a cascade of events leading to muscle cell degeneration, chronic inflammation, and deposition of fibrotic and adipose tissue. Efforts in the last decade have led to the clinical approval of novel drugs for DMD that aim to restore dystrophin function. However, combination therapies able to restore dystrophin expression and target the myriad of cellular events found impaired in dystrophic muscle are desirable. Muscles are higher energy consumers susceptible to mitochondrial defects. Mitochondria generate a significant source of reactive oxygen species (ROS), and they are, in turn, sensitive to proper redox balance. In both DMD patients and animal models there is compelling evidence that mitochondrial impairments have a key role in the failure of energy homeostasis. Here, we highlighted the main aspects of mitochondrial dysfunction and oxidative stress in DMD and discussed the recent findings linked to mitochondria/ROS-targeted molecules as a therapeutic approach. In this respect, dual targeting of both mitochondria and redox homeostasis emerges as a potential clinical option in DMD.
Topics: Animals; Humans; Muscular Dystrophy, Duchenne; Dystrophin; Reactive Oxygen Species; Muscle, Skeletal; Mitochondria
PubMed: 38607013
DOI: 10.3390/cells13070574 -
Proteomics Dec 2022The X-linked inherited neuromuscular disorder Duchenne muscular dystrophy is characterised by primary abnormalities in the membrane cytoskeletal component dystrophin.... (Review)
Review
The X-linked inherited neuromuscular disorder Duchenne muscular dystrophy is characterised by primary abnormalities in the membrane cytoskeletal component dystrophin. The almost complete absence of the Dp427-M isoform of dystrophin in skeletal muscles renders contractile fibres more susceptible to progressive degeneration and a leaky sarcolemma membrane. This in turn results in abnormal calcium homeostasis, enhanced proteolysis and impaired excitation-contraction coupling. Biochemical and mass spectrometry-based proteomic studies of both patient biopsy specimens and genetic animal models of dystrophinopathy have demonstrated significant changes in the concentration and/or physiological function of essential calcium-regulatory proteins in dystrophin-lacking voluntary muscles. Abnormalities include dystrophinopathy-associated changes in voltage sensing receptors, calcium release channels, calcium pumps and calcium binding proteins. This review article provides an overview of the importance of the sarcolemmal dystrophin-glycoprotein complex and the wider dystrophin complexome in skeletal muscle and its linkage to depolarisation-induced calcium-release mechanisms and the excitation-contraction-relaxation cycle. Besides chronic inflammation, fat substitution and reactive myofibrosis, a major pathobiochemical hallmark of X-linked muscular dystrophy is represented by the chronic influx of calcium ions through the damaged plasmalemma in conjunction with abnormal intracellular calcium fluxes and buffering. Impaired calcium handling proteins should therefore be included in an improved biomarker signature of Duchenne muscular dystrophy.
Topics: Animals; Dystrophin; Muscular Dystrophy, Duchenne; Proteomics; Calcium; Mass Spectrometry; Muscle, Skeletal
PubMed: 35902360
DOI: 10.1002/pmic.202200003 -
Science Translational Medicine Jan 2023Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disease caused by the absence of dystrophin, a membrane-stabilizing protein encoded by the gene....
Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disease caused by the absence of dystrophin, a membrane-stabilizing protein encoded by the gene. Although mouse models of DMD provide insight into the potential of a corrective therapy, data from genetically homologous large animals, such as the dystrophin-deficient golden retriever muscular dystrophy (GRMD) model, may more readily translate to humans. To evaluate the clinical translatability of an adeno-associated virus serotype 9 vector (AAV9)-microdystrophin (μDys5) construct, we performed a blinded, placebo-controlled study in which 12 GRMD dogs were divided among four dose groups [control, 1 × 10 vector genomes per kilogram (vg/kg), 1 × 10 vg/kg, and 2 × 10 vg/kg; = 3 each], treated intravenously at 3 months of age with a canine codon-optimized microdystrophin construct, rAAV9-CK8e-c-μDys5, and followed for 90 days after dosing. All dogs received prednisone (1 milligram/kilogram) for a total of 5 weeks from day -7 through day 28. We observed dose-dependent increases in tissue vector genome copy numbers; μDys5 protein in multiple appendicular muscles, the diaphragm, and heart; limb and respiratory muscle functional improvement; and reduction of histopathologic lesions. As expected, given that a truncated dystrophin protein was generated, phenotypic test results and histopathologic lesions did not fully normalize. All administrations were well tolerated, and adverse events were not seen. These data suggest that systemically administered AAV-microdystrophin may be dosed safely and could provide therapeutic benefit for patients with DMD.
Topics: Animals; Dogs; Humans; Infant, Newborn; Mice; Dystrophin; Genetic Therapy; Heart; Muscle, Skeletal; Muscles; Muscular Dystrophy, Animal; Muscular Dystrophy, Duchenne
PubMed: 36599002
DOI: 10.1126/scitranslmed.abo1815 -
Scientific Reports Mar 2023Dystrophin maintains membrane integrity as a sarcolemmal protein. Dystrophin mutations lead to Duchenne muscular dystrophy, an X-linked recessive disorder. Since...
Dystrophin maintains membrane integrity as a sarcolemmal protein. Dystrophin mutations lead to Duchenne muscular dystrophy, an X-linked recessive disorder. Since dystrophin is one of the largest genes consisting of 79 exons in the human genome, delivering a full-length dystrophin using virus vectors is challenging for gene therapy. Human artificial chromosome is a vector that can load megabase-sized genome without any interference from the host chromosome. Chimeric mice carrying a 2.4-Mb human dystrophin gene-loaded human artificial chromosome (DYS-HAC) was previously generated, and dystrophin expression from DYS-HAC was confirmed in skeletal muscles. Here we investigated whether human dystrophin expression from DYS-HAC rescues the muscle phenotypes seen in dystrophin-deficient mice. Human dystrophin was normally expressed in the sarcolemma of skeletal muscle and heart at expected molecular weights, and it ameliorated histological and functional alterations in dystrophin-deficient mice. These results indicate that the 2.4-Mb gene is enough for dystrophin to be correctly transcribed and translated, improving muscular dystrophy. Therefore, this technique using HAC gives insight into developing new treatments and novel humanized Duchenne muscular dystrophy mouse models with human dystrophin gene mutations.
Topics: Animals; Humans; Mice; Chromosomes, Artificial, Human; Disease Models, Animal; Dystrophin; Mice, Inbred mdx; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Sarcolemma
PubMed: 36928364
DOI: 10.1038/s41598-023-31481-3 -
Biochimica Et Biophysica Acta.... Jan 2021The molecular and cellular basis for cataract development in mice lacking dystrophin, a scaffolding protein that links the cytoskeleton to the extracellular matrix, is...
The molecular and cellular basis for cataract development in mice lacking dystrophin, a scaffolding protein that links the cytoskeleton to the extracellular matrix, is poorly understood. In this study, we characterized lenses derived from the dystrophin-deficient mdx mouse model. Expression of Dp71, a predominant isoform of dystrophin in the lens, was induced during lens fiber cell differentiation. Dp71 was found to co-distribute with dystroglycan, connexin-50 and 46, aquaporin-0, and NrCAM as a large cluster at the center of long arms of the hexagonal fibers. Although mdx mouse lenses exhibited dramatically reduced levels of Dp71, only older lenses revealed punctate nuclear opacities compared to littermate wild type (WT) lenses. The levels of dystroglycan, syntrophin, and dystrobrevin which comprise the dystrophin-associated protein complex (DAPC), and NrCAM, connexin-50, and aquaporin-0, were significantly lower in the lens membrane fraction of adult mdx mice compared to WT mice. Additionally, decreases were observed in myosin light chain phosphorylation and lens stiffness together with a significant elevation in the levels of utrophin, a functional homolog of dystrophin in mdx mouse lenses compared to WT lenses. The levels of perlecan and laminin (ligands of α-dystroglycan) remained normal in dystrophin-deficient lens fibers. Taken together, although mdx mouse lenses exhibit only minor defects in lens clarity possibly due to a compensatory increase in utrophin, the noted disruptions of DAPC, stability, and organization of membrane integral proteins of fibers, and stiffness of mdx lenses reveal the importance of dystrophin and DAPC in maintaining lens clarity and function.
Topics: Animals; Dystrophin; Eye Proteins; Gene Expression Regulation; Lens, Crystalline; Mice; Mice, Inbred mdx
PubMed: 33127476
DOI: 10.1016/j.bbadis.2020.165998 -
Nucleic Acids Research Jul 2022Targeted chromosomal insertion of large genetic payloads in human cells leverages and broadens synthetic biology and genetic therapy efforts. Yet, obtaining large-scale...
Targeted chromosomal insertion of large genetic payloads in human cells leverages and broadens synthetic biology and genetic therapy efforts. Yet, obtaining large-scale gene knock-ins remains particularly challenging especially in hard-to-transfect stem and progenitor cells. Here, fully viral gene-deleted adenovector particles (AdVPs) are investigated as sources of optimized high-specificity CRISPR-Cas9 nucleases and donor DNA constructs tailored for targeted insertion of full-length dystrophin expression units (up to 14.8-kb) through homologous recombination (HR) or homology-mediated end joining (HMEJ). In muscle progenitor cells, donors prone to HMEJ yielded higher CRISPR-Cas9-dependent genome editing frequencies than HR donors, with values ranging between 6% and 34%. In contrast, AdVP transduction of HR and HMEJ substrates in induced pluripotent stem cells (iPSCs) resulted in similar CRISPR-Cas9-dependent genome editing levels. Notably, when compared to regular iPSCs, in p53 knockdown iPSCs, CRISPR-Cas9-dependent genome editing frequencies increased up to 6.7-fold specifically when transducing HMEJ donor constructs. Finally, single DNA molecule analysis by molecular combing confirmed that AdVP-based genome editing achieves long-term complementation of DMD-causing mutations through the site-specific insertion of full-length dystrophin expression units. In conclusion, AdVPs are a robust and flexible platform for installing large genomic edits in human cells and p53 inhibition fosters HMEJ-based genome editing in iPSCs.
Topics: CRISPR-Cas Systems; Dystrophin; Endonucleases; Gene Editing; Humans; Muscle Cells; Muscular Dystrophy, Duchenne; Tumor Suppressor Protein p53
PubMed: 35776127
DOI: 10.1093/nar/gkac567 -
American Journal of Physiology.... Dec 2023Duchenne muscular dystrophy (DMD), a progressive muscle disease caused by the absence of functional dystrophin protein, is associated with multiple cellular,...
Duchenne muscular dystrophy (DMD), a progressive muscle disease caused by the absence of functional dystrophin protein, is associated with multiple cellular, physiological, and metabolic dysfunctions. As an added complication to the primary insult, obesity/insulin resistance (O/IR) is frequently reported in patients with DMD; however, how IR impacts disease severity is unknown. We hypothesized a high-fat, high-sucrose diet (HFHSD) would induce O/IR, exacerbate disease severity, and cause metabolic alterations in dystrophic mice. To test this hypothesis, we treated 7-wk-old mdx (disease model) and C57 mice with a control diet (CD) or an HFHSD for 15 wk. The HFHSD induced insulin resistance, glucose intolerance, and hyperglycemia in C57 and mdx mice. Of note, mdx mice on CD were also insulin resistant. In addition, visceral adipose tissue weights were increased with HFHSD in C57 and mdx mice though differed by genotype. Serum creatine kinase activity and histopathological analyses using Masson's trichrome staining in the diaphragm indicated muscle damage was driven by dystrophin deficiency but was not augmented by diet. In addition, markers of inflammatory signaling, mitochondrial abundance, and autophagy were impacted by disease but not diet. Despite this, in addition to disease signatures in CD-fed mice, metabolomic and lipidomic analyses demonstrated a HFHSD caused some common changes in C57 and mdx mice and some unique signatures of O/IR within the context of dystrophin deficiency. In total, these data revealed that in mdx mice, 15 wk of HFHSD did not overtly exacerbate muscle injury but further impaired the metabolic status of dystrophic muscle.
Topics: Humans; Animals; Mice; Mice, Inbred mdx; Dystrophin; Muscle, Skeletal; Sucrose; Insulin Resistance; Muscular Dystrophy, Duchenne; Diet, High-Fat; Disease Models, Animal
PubMed: 37811713
DOI: 10.1152/ajpregu.00246.2022