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FEBS Letters Sep 2000Defects in the dystrophin complex (DC) underlie several human genetic disorders, but our dissection of its function is complicated by potential redundancy of the... (Review)
Review
Defects in the dystrophin complex (DC) underlie several human genetic disorders, but our dissection of its function is complicated by potential redundancy of the multiple vertebrate isoforms of most DC components. We here complete our previous description of Drosophila dystrophin, and show that the fly retains all essential components of the DC, but with substantially less diversity. Seventeen known human components (three dystrophin-related proteins, two dystrobrevins, five sarcoglycans, five syntrophins, one dystroglycan and one sarcospan) appear to be reduced to eight in Drosophila (one, one, three, two, one and none, respectively). The simplicity of this system recommends it as a model for its human counterpart.
Topics: Amino Acid Sequence; Animals; Drosophila; Dystrophin; Humans; Invertebrates; Molecular Sequence Data; Phylogeny; Sequence Alignment; Sequence Homology, Amino Acid; Vertebrates
PubMed: 11018515
DOI: 10.1016/s0014-5793(00)02018-4 -
Human Molecular Genetics Jun 2023
Topics: Animals; Mice; Dystrophin; Exons; Muscle Cells; Mice, Inbred mdx; Muscular Dystrophy, Duchenne
PubMed: 36892271
DOI: 10.1093/hmg/ddad038 -
Journal of Muscle Research and Cell... 2006It is 20 years since the discovery of the genetic defect causing Duchenne muscular dystrophy (DMD). This X-linked progressive and fatal myopathy is due to the absence of... (Review)
Review
It is 20 years since the discovery of the genetic defect causing Duchenne muscular dystrophy (DMD). This X-linked progressive and fatal myopathy is due to the absence of a functional version of a critical sub-sarcolemmal protein called dystrophin that appears to act both as a structural and as a signalling molecule in the muscle fibre. A number of molecular approaches have been developed to restore the expression of dystrophin in DMD patients. Pre-clinical experiments have demonstrated the potential of delivery of recombinant versions of the DMD gene using viral or non-viral vectors and importantly several of these systems are compatible with vascular delivery, an essential feature as all muscles are affected in this condition. Other studies have shown that antisense oligonucleotides can modify the splicing of the primary transcript to provide an internally truncated but still functional protein. Alternatively, in approximately 10-20% of cases it is possible to chemically persuade the translational machinery to read-through a pre-mature stop codon. The pre-clinical results of the last 4 years have encouraged the development of clinical trials for all of the above.
Topics: Animals; Disease Models, Animal; Drug Evaluation, Preclinical; Dystrophin; Gene Expression; Genetic Therapy; Genetic Vectors; Humans; Muscular Dystrophy, Duchenne; Oligonucleotides, Antisense
PubMed: 16874449
DOI: 10.1007/s10974-006-9081-6 -
Gene Therapy Feb 2023Dystrophin deficiency due to genetic mutations causes cardiac abnormalities in Duchenne's muscular dystrophy. Dystrophin is also shown to be downregulated in...
Dystrophin deficiency due to genetic mutations causes cardiac abnormalities in Duchenne's muscular dystrophy. Dystrophin is also shown to be downregulated in conventional failing hearts. Whether restoration of dystrophin expression possesses any therapeutic potential for conventional heart failure (HF) remains to be examined. HF mouse model was generated by transverse aortic constriction (TAC). In vivo activation of dystrophin transcription was achieved by tail-vein injection of adeno-associated virus 9 carrying CRISPR/dCas system for dystrophin. We found that activation of dystrophin expression in TAC mice significantly reduced the susceptibility to arrhythmia of TAC mice and the mortality rate. We further demonstrated that over-expression of dystrophin increased cardiac conduction of hearts in TAC mice by optical mapping evaluation. Activation of dystrophin expression also increased peak sodium current in isolated ventricular myocytes from hearts of TAC mice as recorded by the patch-clamp technique. Immunoblotting and immunofluorescence showed that increased dystrophin transcription restored the membrane distribution of Nav1.5 in the hearts of TAC mice. In summary, correction of dystrophin downregulation by the CRISPR-dCas9 system reduced the susceptibility to arrhythmia of conventional HF mice through restoring Nav1.5 membrane distribution. This study paved the way to develop a new therapeutic strategy for HF-related ventricular arrhythmia.
Topics: Mice; Animals; Dystrophin; Clustered Regularly Interspaced Short Palindromic Repeats; Arrhythmias, Cardiac; Muscular Dystrophy, Duchenne; Heart Failure
PubMed: 35644811
DOI: 10.1038/s41434-022-00348-z -
Nature Communications Aug 2023Duchenne muscular dystrophy is caused by mutations in the DMD gene, leading to lack of dystrophin. Chronic muscle damage eventually leads to histological alterations in...
Duchenne muscular dystrophy is caused by mutations in the DMD gene, leading to lack of dystrophin. Chronic muscle damage eventually leads to histological alterations in skeletal muscles. The identification of genes and cell types driving tissue remodeling is a key step to developing effective therapies. Here we use spatial transcriptomics in two Duchenne muscular dystrophy mouse models differing in disease severity to identify gene expression signatures underlying skeletal muscle pathology and to directly link gene expression to muscle histology. We perform deconvolution analysis to identify cell types contributing to histological alterations. We show increased expression of specific genes in areas of muscle regeneration (Myl4, Sparc, Hspg2), fibrosis (Vim, Fn1, Thbs4) and calcification (Bgn, Ctsk, Spp1). These findings are confirmed by smFISH. Finally, we use differentiation dynamic analysis in the D2-mdx muscle to identify muscle fibers in the present state that are predicted to become affected in the future state.
Topics: Animals; Mice; Muscular Dystrophy, Duchenne; Transcriptome; Mice, Inbred mdx; Muscle, Skeletal; Dystrophin; Disease Models, Animal
PubMed: 37582915
DOI: 10.1038/s41467-023-40555-9 -
Current Opinion in Pediatrics Dec 1996Major advances in the genetic understanding of the limb-girdle (LGMD) and congenital (CMD) muscular dystrophies have led to a new, genetically based classification of... (Review)
Review
Major advances in the genetic understanding of the limb-girdle (LGMD) and congenital (CMD) muscular dystrophies have led to a new, genetically based classification of these disorders. The definition of the complex of dystrophin-associated proteins on a biochemical and subsequently genetic level has greatly accelerated this progress by providing candidate genes to complement or replace the process of linkage analysis either in families with muscular dystrophy or in sporadic cases. The major components of the dystrophin-associated proteins now known to be involved in muscular dystrophy besides dystrophin itself ar the sarcoglycan complex and the alpha 2-chain (merosin) of laminin-2 in the extracellular matrix. Mutations in the various sarcoglycans account for four types of autosomal recessive LGMD of varying severity (types 2C through 2F), including severe childhood-onset presentations. One type of autosomal recessive LGMD (type 2A) is caused by mutations in the protease calpain-3, whereas the gene for type 2B has not yet been identified, although the responsible locus has been assigned to chromosome 2p13. There are different autosomal dominant forms as well, one of which has been mapped to chromosome 5q31. With regard to CMDs, the major breakthrough involves a type of "classic" CMD with abnormalities of the white matter on magnetic resonance imaging of the brain. These patients show deficiencies of the laminin alpha 2-chain, and mutations in the corresponding gene have been identified. The group of laminin alpha 2-chain-positive classic CMD likely is heterogeneous. Among the group of CMDs with abnormalities of brain formation and mental retardation, genetic, immunohistochemical, and clinical differences are now beginning to emerge to help in the distinction between Fukuyama muscular dystrophy, the Walker-Warburg syndrome, and muscle-eye-brain disease.
Topics: Dystrophin; Humans; Muscular Dystrophies
PubMed: 9018440
DOI: No ID Found -
The Journal of Biological Chemistry May 2018Dystrophin, encoded by the gene, is critical for maintaining plasma membrane integrity during muscle contraction events. Mutations in the gene disrupting the reading...
Dystrophin, encoded by the gene, is critical for maintaining plasma membrane integrity during muscle contraction events. Mutations in the gene disrupting the reading frame prevent dystrophin production and result in severe Duchenne muscular dystrophy (DMD); in-frame internal deletions allow production of partly functional internally deleted dystrophin and result in less severe Becker muscular dystrophy (BMD). Many known BMD deletions occur in dystrophin's central domain, generally considered to be a monotonous rod-shaped domain based on the knowledge of spectrin family proteins. However, the effects caused by these deletions, ranging from asymptomatic to severe BMD, argue against the central domain serving only as a featureless scaffold. We undertook structural studies combining small-angle X-ray scattering and molecular modeling in an effort to uncover the structure of the central domain, as dystrophin has been refractory to characterization. We show that this domain appears to be a tortuous and complex filament that is profoundly disorganized by the most severe BMD deletion (loss of exons 45-47). Despite the preservation of large parts of the binding site for neuronal nitric oxide synthase (nNOS) in this deletion, computational approaches failed to recreate the association of dystrophin with nNOS. This observation is in agreement with a strong decrease of nNOS immunolocalization in muscle biopsies, a parameter related to the severity of BMD phenotypes. The structural description of the whole dystrophin central domain we present here is a first necessary step to improve the design of microdystrophin constructs toward the goal of a successful gene therapy for DMD.
Topics: Binding Sites; Dystrophin; Exons; Gene Deletion; Humans; Molecular Docking Simulation; Muscular Dystrophy, Duchenne; Nitric Oxide Synthase Type I; Protein Domains; Reading Frames; Scattering, Small Angle; Solutions; X-Ray Diffraction
PubMed: 29535188
DOI: 10.1074/jbc.M117.809798 -
Scientific Reports Oct 2020Dystrophin Dp71 is the smallest isoform of the DMD gene, mutations in which cause Duchenne muscular dystrophy (DMD). Dp71 has also been shown to have roles in various...
Dystrophin Dp71 is the smallest isoform of the DMD gene, mutations in which cause Duchenne muscular dystrophy (DMD). Dp71 has also been shown to have roles in various cellular processes. Stem cell-based therapy may be effective in treating DMD, but the inability to generate a sufficient number of stem cells remains a significant obstacle. Although Dp71 is comprised of many variants, Dp71 in satellite cells has not yet been studied. Here, the full-length Dp71 consisting of 18 exons from exons G1 to 79 was amplified by reverse transcription-PCR from total RNA of human satellite cells. The amplified product showed deletion of both exons 71 and 78 in all sequenced clones, indicating monoclonal expression of Dp71ab. Western blotting of the satellite cell lysate showed a band corresponding to over-expressed Dp71ab. Transfection of a plasmid expressing Dp71ab into human myoblasts significantly enhanced cell proliferation when compared to the cells transfected with the mock plasmid. However, transfection of the Dp71 expression plasmid encoding all 18 exons did not enhance myoblast proliferation. These findings indicated that Dp71ab, but not Dp71, is a molecular enhancer of myoblast proliferation and that transfection with Dp71ab may generate a high yield of stem cells for DMD treatment.
Topics: Blotting, Western; Cell Proliferation; Dystrophin; Humans; Muscular Dystrophy, Duchenne; Myoblasts; Reverse Transcriptase Polymerase Chain Reaction; Satellite Cells, Skeletal Muscle; Transcriptome
PubMed: 33051488
DOI: 10.1038/s41598-020-74157-y -
Methods in Molecular Biology (Clifton,... 2023Duchenne muscular dystrophy (DMD) is a progressive myopathy caused by mutations in genes encoding dystrophin proteins that ultimately lead to depletion of myogenic...
Duchenne muscular dystrophy (DMD) is a progressive myopathy caused by mutations in genes encoding dystrophin proteins that ultimately lead to depletion of myogenic progenitor cells (MPCs). Several approaches have been used to correctly express the dystrophin gene in induced pluripotent stem cells (iPSCs), including deletion of mutated exon 23 (ΔEx23) by clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated gene 9 (Cas9)-mediated gene editing technology. However, this approach is labor-intensive due to individual colony picking and genotyping to verify allelic modification. Here, we present a protocol to restore the function of the dystrophin gene by using homology-directed repair (HDR)-based CRISPR/Cas9 and inducing myogenic program of reprogrammed iPSCs from Mdx mice by inducible muscle-specific transcription factor MyoD.
Topics: Mice; Animals; Dystrophin; CRISPR-Cas Systems; Mice, Inbred mdx; Myoblasts; Muscles; Technology
PubMed: 36401043
DOI: 10.1007/978-1-0716-2772-3_23 -
International Journal of Molecular... May 2023Mutations that prevent the production of proteins in the gene cause Duchenne muscular dystrophy. Most frequently, these are deletions leading to reading-frame shift....
Mutations that prevent the production of proteins in the gene cause Duchenne muscular dystrophy. Most frequently, these are deletions leading to reading-frame shift. The "reading-frame rule" states that deletions that preserve ORF result in a milder Becker muscular dystrophy. By removing several exons, new genome editing tools enable reading-frame restoration in DMD with the production of BMD-like dystrophins. However, not every truncated dystrophin with a significant internal loss functions properly. To determine the effectiveness of potential genome editing, each variant should be carefully studied in vitro or in vivo. In this study, we focused on the deletion of exons 8-50 as a potential reading-frame restoration option. Using the CRISPR-Cas9 tool, we created the novel mouse model DMDdel8-50, which has an in-frame deletion in the gene. We compared DMDdel8-50 mice to C57Bl6/CBA background control mice and previously generated DMDdel8-34 KO mice. We discovered that the shortened protein was expressed and correctly localized on the sarcolemma. The truncated protein, on the other hand, was unable to function like a full-length dystrophin and prevent disease progression. On the basis of protein expression, histological examination, and physical assessment of the mice, we concluded that the deletion of exons 8-50 is an exception to the reading-frame rule.
Topics: Mice; Animals; Dystrophin; Mice, Inbred CBA; Muscular Dystrophy, Duchenne; Phenotype; Exons; Gene Deletion
PubMed: 37298068
DOI: 10.3390/ijms24119117