Cell fractionation studies indicate that dystrophin is a protein of surface membranes of skeletal muscle.
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ABSTRACT:
SUBMITTER: Salviati G
PROVIDER: S-EPMC1138440 | biostudies-other | 1989 Mar
REPOSITORIES: biostudies-other
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Project description:Supramolecular membrane complexes of low abundance are difficult to study by routine bioanalytical techniques. The plasmalemmal complex consisting of sarcoglycans, dystroglycans, dystrobrevins and syntrophins, which is closely associated with the membrane cytoskeletal protein dystrophin, represents such a high?molecular?mass protein assembly in skeletal muscles. The almost complete loss of the dystrophin isoform Dp427?M and concomitant reduction in the dystrophin?associated glycoprotein complex is the underlying cause of the highly progressive neuromuscular disorder named Duchenne muscular dystrophy. This gives the detailed characterization of the dystrophin complex considerable pathophysiological importance. In order to carry out a comprehensive mass spectrometric identification of the dystrophin?glycoprotein complex, in this study, we used extensive subcellular fractionation and enrichment procedures prior to subproteomic analysis. Mass spectrometry identified high levels of full?length dystrophin isoform Dp427?M, ?/??dystroglycans, ?/?/?/??sarcoglycans, ?1/?1/?2?syntrophins and ?/??dystrobrevins in highly purified sarcolemma vesicles. By contrast, lower levels were detected in transverse tubules and no components of the dystrophin complex were identified in triads. For comparative purposes, the presence of organellar marker proteins was studied in crude surface membrane preparations vs. enriched fractions from the sarcolemma, transverse tubules and triad junctions using gradient gel electrophoresis and on?membrane digestion. This involved the subproteomic assessment of various ion?regulatory proteins and excitation?contraction coupling components. The comparative profiling of skeletal muscle fractions established a relatively restricted subcellular localization of the dystrophin?glycoprotein complex in the muscle fibre periphery by proteomic means and clearly demonstrated the absence of dystrophin from triad junctions by sensitive mass spectrometric analysis.
| S-EPMC5593493 | biostudies-literature
Project description:Quantitation of human dystrophin protein in muscle biopsies is a clinically relevant endpoint for both diagnosis and response to dystrophin-replacement therapies for dystrophinopathies. A robust and accurate assay would enable the use of dystrophin as a surrogate biomarker, particularly in exploratory Phase 2 trials. Currently available methods to quantitate dystrophin rely on immunoblot or immunohistochemistry methods that are not considered robust. Here we present a mass spectrometry based approach to accurately quantitate dystrophin protein in a total protein extract from human muscle biopsies. Our approach uses a combination of stable isotope labeled dystrophin as a spike-in standard, gel electrophoresis and high precision mass spectrometry to detect and quantitate multiple peptides of dystrophin within a complex protein mixture. The method was found highly reproducible and linear over a wide dynamic range, detecting as low as 5% of dystrophin relative to the normal amount in healthy individuals.
| S-EPMC3642779 | biostudies-literature
Project description:BACKGROUND:We are developing a novel therapy for Duchenne muscular dystrophy (DMD), involving the transplantation of autologous, skeletal muscle-derived stem cells that have been genetically corrected to express dystrophin. Dystrophin is normally expressed in activated satellite cells and in differentiated muscle fibres. However, in past preclinical validation studies, dystrophin transgenes have generally been driven by constitutive promoters that would be active at every stage of the myogenic differentiation process, including in proliferating muscle stem cells. It is not known whether artificial dystrophin expression would affect the properties of these cells. AIMS:Our aims are to determine if mini-dystrophin expression affects the proliferation or myogenic differentiation of DMD skeletal muscle-derived cells. METHODS:Skeletal muscle-derived cells from a DMD patient were transduced with lentivirus coding for mini-dystrophins (R3-R13 spectrin-like repeats (?R3R13) or hinge2 to spectrin-like repeats R23 (?H2R23)) with EGFP (enhanced green fluorescence protein) fused to the C-terminus, driven by a constitutive promoter, spleen focus-forming virus (SFFV). Transduced cells were purified on the basis of GFP expression. Their proliferation and myogenic differentiation were quantified by ethynyl deoxyuridine (EdU) incorporation and fusion index. Furthermore, dystrophin small interfering ribonucleic acids (siRNAs) were transfected to the cells to reverse the effects of the mini-dystrophin. Finally, a phospho-mitogen-activated protein kinase (MAPK) array assay was performed to investigate signalling pathway changes caused by dystrophin expression. RESULTS:Cell proliferation was not affected in cells transduced with ?R3R13, but was significantly increased in cells transduced with ?H2R23. The fusion index of myotubes derived from both ?R3R13- and ?H2R23 -expressing cells was significantly compromised in comparison to myotubes derived from non-transduced cells. Dystrophin siRNA transfection restored the differentiation of ?H2R23-expressing cells. The Erk1/2- signalling pathway is altered in cells transduced with mini-dystrophin constructs. CONCLUSIONS:Ectopic expression of dystrophin in cultured human skeletal muscle-derived cells may affect their proliferation and differentiation capacity. Caution should be taken when considering genetic correction of autologous stem cells to express dystrophin driven by a constitutive promoter.
| S-EPMC7582244 | biostudies-literature
Project description:The purpose of this investigation was to determine the extent to which dystrophin insufficiency caused histomorphological changes in a novel pig model of Becker muscular dystrophy. In our procedures, we used a combination of biochemical approaches, including quantitative PCR and Western blots, along with a histological analysis using standard and immunohistological measures. We found that 8-wk-old male affected pigs had a 70% reduction in dystrophin protein abundance in the diaphragm, psoas major, and longissimus lumborum and a 5-fold increase in serum creatine kinase activity compared with healthy male littermates. Dystrophin insufficiency in the diaphragm and the longissimus resulted in muscle histopathology with disorganized fibrosis that often colocalized with fatty infiltration but not the psoas. Affected animals also had an 80-85% reduction in ?-sarcoglycan localization in these muscles, indicating compromised assembly of the dystrophin glycoprotein complex. Controls used in this study were 4 healthy male littermates, as they are most closely related to the affected animals. We concluded that pigs with insufficient dystrophin protein expression have a phenotype consistent with human dystrophinopathy patients. Given that and their similarity in body size and physiology to humans, we further conclude that this pig line is an appropriate translational model for dystrophinopathies.
| S-EPMC3963011 | biostudies-literature
Project description:1. Two distinct classes of protein were detected at the surface of chick-embryo skeletal-muscle cells after iodination of the cells in monolayer culture. 2. The two classes of iodinated proteins differed in their ability to co-purify with a vesicular plasma-membrane fraction prepared from surface-labelled cells. 3. One class consisted of predominantly high-molecular-weight glycoproteins that co-purified with the plasma-membrane fraction, but showed no significant qualitative or quantitative alterations in labelling with 125I and lactoperoxidase during myogenesis. 4. A second class of predominantly lower-molecular-weight proteins showed reproducible quantitative alterations in 125I-labelling during myogenesis but failed to co-purify with the plasma-membrane fraction. 5. This second class of proteins may represent matrix proteins involved in intercellular adhesion or adhesion of cells to the substratum. They are unlikely to be directly required for the process of plasma-membrane fusion during myogenesis, since they do not copurify with a vesicular plasma-membrane fraction known to be capable of Ca2+-dependent fusion in vitro.
| S-EPMC1161521 | biostudies-other
Project description:Emerging and promising therapeutic interventions for Duchenne muscular dystrophy (DMD) are confounded by the challenges of quantifying dystrophin. Current approaches have poor precision, require large amounts of tissue, and are difficult to standardize. This paper presents an immuno-mass spectrometry imaging method using gadolinium (Gd)-labeled anti-dystrophin antibodies and laser ablation-inductively coupled plasma-mass spectrometry to simultaneously quantify and localize dystrophin in muscle sections. Gd is quantified as a proxy for the relative expression of dystrophin and was validated in murine and human skeletal muscle sections following k-means clustering segmentation, before application to DMD patients with different gene mutations where dystrophin expression was measured up to 100 µg kg-1 Gd. These results demonstrate that immuno-mass spectrometry imaging is a viable approach for pre-clinical to clinical research in DMD. It rapidly quantified relative dystrophin in single tissue sections, efficiently used valuable patient resources, and may provide information on drug efficacy for clinical translation.
| S-EPMC7806610 | biostudies-literature
Project description:ObjectivesDuchene muscular dystrophy (DMD) is a progressive neuromuscular disease caused by mutations in the DMD gene, resulting in the absence of dystrophin expression leading to membrane fragility and myofibril necrosis in the muscle cells. Because of progressive weakness in the skeletal and cardiac muscles, premature death is inevitable. There is no curative treatment available for DMD. In recent years, advances in genetic engineering tools have made it possible to manipulate gene sequences and accurately modify disease-causing mutations. CRISPR/Cas9 technology is a promising tool for gene editing because of its ability to induce double-strand breaks in the DNA.Materials and methodsIn this study for the exon-skipping approach, we designed a new pair of guide RNAs (gRNA) to induce large deletion of exons 48 to 53 in the DMD gene in the human skeletal muscle cell line (HSkMC), in order to correct the frame of the gene.ResultsData showed successful editing of DMD gene by deletion of exons 48 to 53 and correction of the reading frame in edited cells. Despite a large deletion in the edited DMD gene, the data of real-time PCR, immune florescent staining demonstrated successful expression of truncated dystrophin in edited cells.ConclusionThis study demonstrated that the removal of exons 48-53 by the CRISPR / Cas9 system did not alter the expression of the DMD gene due to the preservation of the reading frame of the gene.
| S-EPMC8591754 | biostudies-literature
Project description:Cell fractionations and other biological separations frequently require several steps. They could be much more effectively done by filtration, if isoporous membranes would be available with high pore density, and sharp pore size distribution in the micro- and nanoscale. We propose a combination of two scalable methods, photolithography and dry reactive ion etching, to fabricate a series of polyester membranes with isopores of size 0.7 to 50 μm and high pore density with a demonstrated total area of 38.5 cm2. The membranes have pore sizes in the micro- and submicro-range, and pore density 10-fold higher than track-etched analogues, which are the only commercially available isoporous polymeric films. Permeances of 220,000 L m-2 h-1bar-1 were measured with pore size 787 nm. The method does not require organic solvents and can be applied to many homopolymeric materials. The pore reduction from 2 to 0.7 μm was obtained by adding a step of chemical vapor deposition. The isoporous system was successfully demonstrated for the organelle fractionation of Arabidopsis homogenates and could be potentially extended to other biological fractionations.
| S-EPMC7145805 | biostudies-literature
Project description:Mutations in the genes coding for either dystrophin or dysferlin cause distinct forms of muscular dystrophy. Dystrophin links the cytoskeleton to the sarcolemma through direct interaction with ?-dystroglycan. This link extends to the extracellular matrix by ?-dystroglycan's interaction with ?-dystroglycan, which binds extracellular matrix proteins, including laminin ?2, agrin and perlecan, that possess laminin globular domains. The absence of dystrophin disrupts this link, leading to compromised muscle sarcolemmal integrity. Dysferlin, on the other hand, plays an important role in the Ca2+-dependent membrane repair of damaged sarcolemma in skeletal muscle. Because dysferlin and dystrophin play different roles in maintaining muscle cell integrity, we hypothesized that disrupting sarcolemmal integrity with dystrophin deficiency would exacerbate the pathology in dysferlin-null mice and allow further characterization of the role of dysferlin in skeletal muscle.To test our hypothesis, we generated dystrophin/dysferlin double-knockout (DKO) mice by breeding mdx mice with dysferlin-null mice and analyzed the effects of a combined deficiency of dysferlin and dystrophin on muscle pathology and sarcolemmal integrity.The DKO mice exhibited more severe muscle pathology than either mdx mice or dysferlin-null mice, and, importantly, the onset of the muscle pathology occurred much earlier than it did in dysferlin-deficient mice. The DKO mice showed muscle pathology of various skeletal muscles, including the mandible muscles, as well as a greater number of regenerating muscle fibers, higher serum creatine kinase levels and elevated Evans blue dye uptake into skeletal muscles. Lengthening contractions caused similar force deficits, regardless of dysferlin expression. However, the rate of force recovery within 45 minutes following lengthening contractions was hampered in DKO muscles compared to mdx muscles or dysferlin-null muscles, suggesting that dysferlin is required for the initial recovery from lengthening contraction-induced muscle injury of the dystrophin-glycoprotein complex-compromised muscles.The results of our study suggest that dysferlin-mediated membrane repair helps to limit the dystrophic changes in dystrophin-deficient skeletal muscle. Dystrophin deficiency unmasks the function of dysferlin in membrane repair during lengthening contractions. Dystrophin/dysferlin-deficient mice provide a very useful model with which to evaluate the effectiveness of therapies designed to treat dysferlin deficiency.
| S-EPMC3287108 | biostudies-literature
Project description:BackgroundDuchenne muscular dystrophy (DMD) is caused by mutations of the gene that encodes the protein dystrophin. A loss of dystrophin leads to severe and progressive muscle wasting in both skeletal and heart muscles. Human induced pluripotent stem cells (hiPSCs) and their derivatives offer important opportunities to treat a number of diseases. Here, we investigated whether givinostat (Givi), a histone deacetylase inhibitor, with muscle differentiation properties could reprogram hiPSCs into muscle progenitor cells (MPC) for DMD treatment.MethodsMPC were generated from hiPSCs by treatment with CHIR99021 and givinostat called Givi-MPC or with CHIR99021 and fibroblast growth factor as control-MPC. The proliferation and migration capacity were investigated by CCK-8, colony, and migration assays. Engraftment, pathological changes, and restoration of dystrophin were evaluated by in vivo transplantation of MPC. Conditioned medium from cultured MPC was collected and analyzed for extracellular vesicles (EVs).ResultsGivi-MPC exhibited superior proliferation and migration capacity compared to control-MPC. Givi-MPC produced less reactive oxygen species (ROS) after oxidative stress and insignificant expression of IL6 after TNF-α stimulation. Upon transplantation in cardiotoxin (CTX)-injured hind limb of Mdx/SCID mice, the Givi-MPC showed robust engraftment and restored dystrophin in the treated muscle than in those treated with control-MPC or human myoblasts. Givi-MPC significantly limited infiltration of inflammatory cells and reduced muscle necrosis and fibrosis. Additionally, Givi-MPC seeded the stem cell pool in the treated muscle. Moreover, EVs released from Givi-MPC were enriched in several miRNAs related to myoangiogenesis including miR-181a, miR-17, miR-210 and miR-107, and miR-19b compared with EVs from human myoblasts.ConclusionsIt is concluded that hiPSCs reprogrammed into MPC by givinostat possessing anti-oxidative, anti-inflammatory, and muscle gene-promoting properties effectively repaired injured muscle and restored dystrophin in the injured muscle.
| S-EPMC7881535 | biostudies-literature