Mechanical stress activates the nuclear factor‐kappaB pathway in skeletal muscle fibers: a possible role in Duchenne muscular dystrophy

2003 ◽  
Vol 17 (3) ◽  
pp. 386-396 ◽  
Author(s):  
Ashok Kumar ◽  
Aladin M. Boriek
Keyword(s):  
Skeletal Muscle ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Mechanical Stress ◽  
Muscle Fibers ◽  
Nuclear Factor Kappab ◽  
Nuclear Factor ◽  
Skeletal Muscle Fibers

scholarly journals Animal Models for Muscular Dystrophy Show Different Patterns of Sarcolemmal Disruption

1997 ◽  
Vol 139 (2) ◽  
pp. 375-385 ◽  
Author(s):  
Volker Straub ◽  
Jill A. Rafael ◽  
Jeffrey S. Chamberlain ◽  
Kevin P. Campbell
Keyword(s):  
Skeletal Muscle ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Animal Models ◽  
Transgenic Mice ◽  
Evans Blue ◽  
Muscle Fibers ◽  
Congenital Muscular Dystrophy ◽  
Mdx Mice ◽  
Skeletal Muscle Fibers

Genetic defects in a number of components of the dystrophin–glycoprotein complex (DGC) lead to distinct forms of muscular dystrophy. However, little is known about how alterations in the DGC are manifested in the pathophysiology present in dystrophic muscle tissue. One hypothesis is that the DGC protects the sarcolemma from contraction-induced damage. Using tracer molecules, we compared sarcolemmal integrity in animal models for muscular dystrophy and in muscular dystrophy patient samples. Evans blue, a low molecular weight diazo dye, does not cross into skeletal muscle fibers in normal mice. In contrast, mdx mice, a dystrophin-deficient animal model for Duchenne muscular dystrophy, showed significant Evans blue accumulation in skeletal muscle fibers. We also studied Evans blue dispersion in transgenic mice bearing different dystrophin mutations, and we demonstrated that cytoskeletal and sarcolemmal attachment of dystrophin might be a necessary requirement to prevent serious fiber damage. The extent of dye incorporation in transgenic mice correlated with the phenotypic severity of similar dystrophin mutations in humans. We furthermore assessed Evans blue incorporation in skeletal muscle of the dystrophia muscularis (dy/dy) mouse and its milder allelic variant, the dy2J/dy2J mouse, animal models for congenital muscular dystrophy. Surprisingly, these mice, which have defects in the laminin α2-chain, an extracellular ligand of the DGC, showed little Evans blue accumulation in their skeletal muscles. Taken together, these results suggest that the pathogenic mechanisms in congenital muscular dystrophy are different from those in Duchenne muscular dystrophy, although the primary defects originate in two components associated with the same protein complex.

Abstract 478: Connexin-43 Reduction Rescues Cardiac and Skeletal Muscle Pathology in a Novel Mouse Model of Duchenne Muscular Dystrophy Symptomatic Carriers

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Julie Nouet ◽  
Eric Himelman ◽  
Diego Fraidenraich
Keyword(s):  
Skeletal Muscle ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Mouse Model ◽  
Muscle Fiber ◽  
Connexin 43 ◽  
Muscle Fibers ◽  
Skeletal Muscle Fiber ◽  
Muscle Pathology ◽  
Female Carriers

Duchenne muscular dystrophy (DMD) and its associated cardiomyopathy manifest in 8-10% of all female carriers however research remains male-centric. Although underrepresented, symptomatic females face the risk of cardiac, respiratory, and skeletal muscle problems. Basic research and clinical trials exclude female carriers therefore developments in treatment expose females to unknown safety and efficacy issues. The bottleneck is largely due to the absence of a faithful mouse model. To generate a mouse model, we injected mdx embryonic stem cells (ESCs) into wild-type (WT) blastocysts ( mdx /WT chimera). The cardiac and skeletal muscle phenotype recapitulates the same generated as a consequence of x-inactivation in human manifesting female patients. In the heart, mdx /WT chimeras develop fibrotic cardiomyopathy. In the skeletal muscle, we found evidence of fibrosis, inflammation and muscle weakness. We found that Connexin-43 (Cx43), the primary gap junctional protein in the heart, was pathologically enhanced and remodeled in mdx /WT chimeras. Cx43 was also enhanced in the dystrophic skeletal muscle. Genetic reduction of Cx43-copy number protected mdx /WT chimeras from cardiac and skeletal muscle fiber damage. The latter result was unexpected because Cx43 is not expressed in mature muscle fibers. Upon further investigation, Cx43 was localized to the mononuclear cells invading the interstitial space between dystrophic skeletal muscle fibers. Pathologically enhanced activity of Cx43 in mdx FACS-macrophages was observed via ethidium bromide uptake and the Cx43 hemichannel peptide mimetic, Gap19, inhibited Cx43 function in a dose-dependent manner. Because an excess of Cx43 has been associated with cell death, we believe that Cx43 reduction in invading mdx macrophages benefits the skeletal muscle of understudied DMD carriers, perhaps by a paracrine mechanism involving macrophage-skeletal muscle fiber communication.

scholarly journals Sarcoplasmic reticulum Ca2+ permeation explored from the lumen side in mdx muscle fibers under voltage control

2012 ◽  
Vol 139 (3) ◽  
pp. 209-218 ◽  
Author(s):  
Gaëlle Robin ◽  
Christine Berthier ◽  
Bruno Allard
Keyword(s):  
Skeletal Muscle ◽  
Duchenne Muscular Dystrophy ◽  
Sarcoplasmic Reticulum ◽  
Muscular Dystrophy ◽  
Action Potentials ◽  
Muscle Fibers ◽  
Cyclopiazonic Acid ◽  
Recovery Phase ◽  
Resting Potential ◽  
Mdx Mice

Under resting conditions, external Ca2+ is known to enter skeletal muscle cells, whereas Ca2+ stored in the sarcoplasmic reticulum (SR) leaks into the cytosol. The nature of the pathways involved in the sarcolemmal Ca2+ entry and in the SR Ca2+ leak is still a matter of debate, but several lines of evidence suggest that these Ca2+ fluxes are up-regulated in Duchenne muscular dystrophy. We investigated here SR calcium permeation at resting potential and in response to depolarization in voltage-controlled skeletal muscle fibers from control and mdx mice, the mouse model of Duchenne muscular dystrophy. Using the cytosolic Ca2+ dye Fura2, we first demonstrated that the rate of Ca2+ increase in response to cyclopiazonic acid (CPA)–induced inhibition of SR Ca2+-ATPases at resting potential was significantly higher in mdx fibers, which suggests an elevated SR Ca2+ leak. However, removal of external Ca2+ reduced the rate of CPA-induced Ca2+ increase in mdx and increased it in control fibers, which indicates an up-regulation of sarcolemmal Ca2+ influx in mdx fibers. Fibers were then loaded with the low-affinity Ca2+ dye Fluo5N-AM to measure intraluminal SR Ca2+ changes. Trains of action potentials, chloro-m-cresol, and depolarization pulses evoked transient Fluo5N fluorescence decreases, and recovery of voltage-induced Fluo5N fluorescence changes were inhibited by CPA, demonstrating that Fluo5N actually reports intraluminal SR Ca2+ changes. Voltage dependence and magnitude of depolarization-induced SR Ca2+ depletion were found to be unchanged in mdx fibers, but the rate of the recovery phase that followed depletion was found to be faster, indicating a higher SR Ca2+ reuptake activity in mdx fibers. Overall, CPA-induced SR Ca2+ leak at −80 mV was found to be significantly higher in mdx fibers and was potentiated by removal of external Ca2+ in control fibers. The elevated passive SR Ca2+ leak may contribute to alteration of Ca2+ homeostasis in mdx muscle.

scholarly journals Multilineage Differentiation for Formation of Innervated Skeletal Muscle Fibers from Healthy and Diseased Human Pluripotent Stem Cells

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1531 ◽  
Author(s):  
Kilian Mazaleyrat ◽  
Cherif Badja ◽  
Natacha Broucqsault ◽  
Raphaël Chevalier ◽  
Camille Laberthonnière ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Muscular Dystrophy ◽  
Pluripotent Stem Cells ◽  
Cell Biology ◽  
Disease Modeling ◽  
Muscle Fibers ◽  
Functional Evaluation ◽  
Skeletal Muscle Fibers ◽  
Human Ipscs

Induced pluripotent stem cells (iPSCs) obtained by reprogramming primary somatic cells have revolutionized the fields of cell biology and disease modeling. However, the number protocols for generating mature muscle fibers with sarcolemmal organization using iPSCs remain limited, and partly mimic the complexity of mature skeletal muscle. Methods: We used a novel combination of small molecules added in a precise sequence for the simultaneous codifferentiation of human iPSCs into skeletal muscle cells and motor neurons. Results: We show that the presence of both cell types reduces the production time for millimeter-long multinucleated muscle fibers with sarcolemmal organization. Muscle fiber contractions are visible in 19–21 days, and can be maintained over long period thanks to the production of innervated multinucleated mature skeletal muscle fibers with autonomous cell regeneration of PAX7-positive cells and extracellular matrix synthesis. The sequential addition of specific molecules recapitulates key steps of human peripheral neurogenesis and myogenesis. Furthermore, this organoid-like culture can be used for functional evaluation and drug screening. Conclusion: Our protocol, which is applicable to hiPSCs from healthy individuals, was validated in Duchenne Muscular Dystrophy, Myotonic Dystrophy, Facio-Scapulo-Humeral Dystrophy and type 2A Limb-Girdle Muscular Dystrophy, opening new paths for the exploration of muscle differentiation, disease modeling and drug discovery.

scholarly journals Description of a Novel Mechanism Possibly Explaining the Antiproliferative Properties of Glucocorticoids in Duchenne Muscular Dystrophy Fibroblasts Based on Glucocorticoid Receptor GR and NFAT5

2020 ◽  
Vol 21 (23) ◽  
pp. 9225
Author(s):  
Sandrine Herbelet ◽  
Boel De Paepe ◽  
Jan L. De Bleecker
Keyword(s):  
Skeletal Muscle ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Glucocorticoid Receptor ◽  
Fibroblast Cell ◽  
Nuclear Factor ◽  
Fibroblast Proliferation ◽  
Activated T Cells ◽  
Fibrotic Tissue ◽  
Fibroblast Cell Culture

Glucocorticoids are drugs of choice in Duchenne muscular dystrophy (DMD), prolonging patients’ ambulation. Their mode of action at the protein level is not completely understood. In DMD, muscle tissue is replaced by fibrotic tissue produced by fibroblasts, reducing mobility. Nuclear factor of activated T-cells 5 (NFAT5) is involved in fibroblast proliferation. By treating one DMD fibroblast cell culture and one of unaffected skeletal muscle fibroblasts with methylprednisolone (MP) or hydrocortisone (HC) for 24 h or 12 d, the antiproliferative properties of glucocorticoids could be unraveled. NFAT5 localization and expression was explored by immunocytochemistry (ICC), Western blotting (WB) and RT-qPCR. NFAT5 and glucocorticoid receptor (GR) colocalization was measured by ImageJ. GR siRNA was used, evaluating GR’s influence on NFAT5 expression during MP and HC treatment. Cell proliferation was monitored by IncuCyte ZOOM. In DMD fibroblasts, treatment with MP for 24 h induced dots (ICC) positive for NFAT5 and colocalizing with GR. After 12 d of MP or HC in DMD fibroblasts, NFAT5 expression was decreased (RT-qPCR and WB) and growth arrest was observed (Incucyte ZOOM), whereas NFAT5 expression and cell growth remained unchanged in unaffected skeletal muscle fibroblasts. This study may help understand the antiproliferative properties of glucocorticoids in DMD fibroblasts.

scholarly journals The PKA-p38MAPK-NFAT5-Organic Osmolytes Pathway in Duchenne Muscular Dystrophy: From Essential Player in Osmotic Homeostasis, Inflammation and Skeletal Muscle Regeneration to Therapeutic Target

Biomedicines ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 350
Author(s):  
Sandrine Herbelet ◽  
Caroline Merckx ◽  
Boel De Paepe
Keyword(s):  
Skeletal Muscle ◽  
Duchenne Muscular Dystrophy ◽  
Protein Kinase ◽  
Muscular Dystrophy ◽  
Muscle Regeneration ◽  
Janus Kinase ◽  
Skeletal Muscle Regeneration ◽  
Organic Osmolytes ◽  
Nuclear Factor ◽  
Osmotic Homeostasis

In Duchenne muscular dystrophy (DMD), the absence of dystrophin from the dystrophin-associated protein complex (DAPC) causes muscle membrane instability, which leads to myofiber necrosis, hampered regeneration, and chronic inflammation. The resulting disabled DAPC-associated cellular pathways have been described both at the molecular and the therapeutical level, with the Toll-like receptor nuclear factor kappa-light-chain-enhancer of activated B cells pathway (NF-ƘB), Janus kinase/signal transducer and activator of transcription proteins, and the transforming growth factor-β pathways receiving the most attention. In this review, we specifically focus on the protein kinase A/ mitogen-activated protein kinase/nuclear factor of activated T-cells 5/organic osmolytes (PKA-p38MAPK-NFAT5-organic osmolytes) pathway. This pathway plays an important role in osmotic homeostasis essential to normal cell physiology via its regulation of the influx/efflux of organic osmolytes. Besides, NFAT5 plays an essential role in cell survival under hyperosmolar conditions, in skeletal muscle regeneration, and in tissue inflammation, closely interacting with the master regulator of inflammation NF-ƘB. We describe the involvement of the PKA-p38MAPK-NFAT5-organic osmolytes pathway in DMD pathophysiology and provide a clear overview of which therapeutic molecules could be of potential benefit to DMD patients. We conclude that modulation of the PKA-p38MAPK-NFAT5-organic osmolytes pathway could be developed as supportive treatment for DMD in conjunction with genetic therapy.

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