Hereditary muscular dystrophy in MDX mice as a homologous model for introduction of cell technologies in the treatment of progressive muscular dystrophies in humans

The alpha7beta1 integrin is the primary laminin receptor on skeletal myoblasts and adult myofibers. It has distinct functions during muscle development and contributes to muscle structural integrity. We have studied this integrin in cases where expression of dystrophin or laminin are compromised. Immunofluorescence demonstrates an increase in alpha7beta1 in patients with Duchenne muscular dystrophy and in mdx mice that lack dystrophin. Analysis of RNA from mdx mice and from patients with Duchenne and Becker muscular dystrophies indicates that the increase in the alpha7beta1 integrin is regulated at the level of alpha7 gene transcription. In contrast, the levels of alpha7beta1 integrin are severely diminished in patients with laminin alpha2 chain congenital dystrophy muscular dystrophy and in dy/dy mice that also do not make the alpha2 laminin chain. Analysis of RNA from the hindlimbs of dy/dy mice demonstrated that in the absence of laminin alpha7 gene transcription is inhibited and limited to specific alternatively spliced isoforms. We suggest that the increased expression of alpha7beta1 integrin in the absence of dystrophin compensates for the reduced dystrophin-mediated linkage of fibers with the basal lamina and modulates the development of pathology associated with these diseases. The decrease in alpha7beta1 integrin and its transcripts in the absence of laminin likely contributes to the severe myopathy that results from laminin alpha2 chain deficiency and suggests that laminin-2 regulates expression of the alpha7 integrin gene. The role of the alpha7beta1 integrin in muscle integrity also suggests that compromised expression of this receptor may underlie as yet undefined myopathies.

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Sarcospan reduces dystrophic pathology: stabilization of the utrophin–glycoprotein complex

The Journal of Cell Biology ◽

10.1083/jcb.200808027 ◽

2008 ◽

Vol 183 (3) ◽

pp. 419-427 ◽

Cited By ~ 35

Author(s):

Angela K. Peter ◽

Jamie L. Marshall ◽

Rachelle H. Crosbie

Keyword(s):

Muscular Dystrophy ◽

Dystrophin Gene ◽

Muscular Dystrophies ◽

Mdx Mice ◽

Future Design ◽

Glycoprotein Complex ◽

Analogous Complex ◽

Dystrophin Glycoprotein Complex ◽

Extrasynaptic Membrane ◽

Dystrophin Glycoprotein

Mutations in the dystrophin gene cause Duchenne muscular dystrophy and result in the loss of dystrophin and the entire dystrophin–glycoprotein complex (DGC) from the sarcolemma. We show that sarcospan (SSPN), a unique tetraspanin-like component of the DGC, ameliorates muscular dystrophy in dystrophin-deficient mdx mice. SSPN stabilizes the sarcolemma by increasing levels of the utrophin–glycoprotein complex (UGC) at the extrasynaptic membrane to compensate for the loss of dystrophin. Utrophin is normally restricted to the neuromuscular junction, where it replaces dystrophin to form a functionally analogous complex. SSPN directly interacts with the UGC and functions to stabilize utrophin protein without increasing utrophin transcription. These findings reveal the importance of protein stability in the prevention of muscular dystrophy and may impact the future design of therapeutics for muscular dystrophies.

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Regenerating myofibers in tibialis anterior muscles of young ‘MDX’ mice

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100127943 ◽

1987 ◽

Vol 45 ◽

pp. 726-727

Author(s):

H. D. Geissinge ◽

L.D. Rhodes

Keyword(s):

Muscular Dystrophy ◽

Mouse Model ◽

Tibialis Anterior ◽

Physiological Activity ◽

Mdx Mice ◽

Mode Of Inheritance

A recently discovered mouse model (‘mdx’) for muscular dystrophy in man may be of considerable interest, since the disease in ‘mdx’ mice is inherited by the same mode of inheritance (X-linked) as the human Duchenne (DMD) muscular dystrophy. Unlike DMD, which results in a situation in which the continual muscle destruction cannot keep up with abortive regenerative attempts of the musculature, and the sufferers of the disease die early, the disease in ‘mdx’ mice appears to be transient, and the mice do not die as a result of it. In fact, it has been reported that the severely damaged Tibialis anterior (TA) muscles of ‘mdx’ mice seem to display exceptionally good regenerative powers at 4-6 weeks, so much so, that these muscles are able to regenerate spontaneously up to their previous levels of physiological activity.

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Faculty Opinions recommendation of Toll-like receptor 4 ablation in mdx mice reveals innate immunity as a therapeutic target in Duchenne muscular dystrophy.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.725296116.793509475 ◽

2015 ◽

Author(s):

James Tidball

Keyword(s):

Innate Immunity ◽

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Therapeutic Target ◽

Mdx Mice ◽

Toll Like Receptor ◽

Toll Like Receptor 4

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Age-Dependent Dysregulation of Muscle Vasculature and Blood Flow Recovery after Hindlimb Ischemia in the mdx Model of Duchenne Muscular Dystrophy

Biomedicines ◽

10.3390/biomedicines9050481 ◽

2021 ◽

Vol 9 (5) ◽

pp. 481

Author(s):

Paulina Podkalicka ◽

Olga Mucha ◽

Katarzyna Kaziród ◽

Iwona Bronisz-Budzyńska ◽

Sophie Ostrowska-Paton ◽

...

Keyword(s):

Blood Flow ◽

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Blood Vessels ◽

Mdx Mice ◽

Hindlimb Ischemia ◽

Double Positive ◽

Functional Studies ◽

Age Dependent ◽

Dystrophic Mice

Duchenne muscular dystrophy (DMD), caused by a lack of functional dystrophin, is characterized by progressive muscle degeneration. Interestingly, dystrophin is also expressed in endothelial cells (ECs), and insufficient angiogenesis has already been hypothesized to contribute to DMD pathology, however, its status in mdx mice, a model of DMD, is still not fully clear. Our study aimed to reveal angiogenesis-related alterations in skeletal muscles of mdx mice compared to wild-type (WT) counterparts. By investigating 6- and 12-week-old mice, we sought to verify if those changes are age-dependent. We utilized a broad spectrum of methods ranging from gene expression analysis, flow cytometry, and immunofluorescence imaging to determine the level of angiogenic markers and to assess muscle blood vessel abundance. Finally, we implemented the hindlimb ischemia (HLI) model, more biologically relevant in the context of functional studies evaluating angiogenesis/arteriogenesis processes. We demonstrated that both 6- and 12-week-old dystrophic mice exhibited dysregulation of several angiogenic factors, including decreased vascular endothelial growth factor A (VEGF) in different muscle types. Nonetheless, in younger, 6-week-old mdx animals, neither the abundance of CD31+α-SMA+ double-positive blood vessels nor basal blood flow and its restoration after HLI was affected. In 12-week-old mdx mice, although a higher number of CD31+α-SMA+ double-positive blood vessels and an increased percentage of skeletal muscle ECs were found, the abundance of pericytes was diminished, and blood flow was reduced. Moreover, impeded perfusion recovery after HLI associated with a blunted inflammatory and regenerative response was evident in 12-week-old dystrophic mice. Hence, our results reinforce the hypothesis of age-dependent angiogenic dysfunction in dystrophic mice. In conclusion, we suggest that older mdx mice constitute an appropriate model for preclinical studies evaluating the effectiveness of vascular-based therapies aimed at the restoration of functional angiogenesis to mitigate DMD severity.

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Annexins and Membrane Repair Dysfunctions in Muscular Dystrophies

International Journal of Molecular Sciences ◽

10.3390/ijms22105276 ◽

2021 ◽

Vol 22 (10) ◽

pp. 5276

Author(s):

Coralie Croissant ◽

Romain Carmeille ◽

Charlotte Brévart ◽

Anthony Bouter

Keyword(s):

Skeletal Muscle ◽

Muscular Dystrophy ◽

Genetic Disorders ◽

Muscle Cells ◽

Cell Types ◽

Clinical Severity ◽

Skeletal Muscle Cells ◽

Muscular Dystrophies ◽

Membrane Repair ◽

Human Skeletal Muscle Cells

Muscular dystrophies constitute a group of genetic disorders that cause weakness and progressive loss of skeletal muscle mass. Among them, Miyoshi muscular dystrophy 1 (MMD1), limb girdle muscular dystrophy type R2 (LGMDR2/2B), and LGMDR12 (2L) are characterized by mutation in gene encoding key membrane-repair protein, which leads to severe dysfunctions in sarcolemma repair. Cell membrane disruption is a physiological event induced by mechanical stress, such as muscle contraction and stretching. Like many eukaryotic cells, muscle fibers possess a protein machinery ensuring fast resealing of damaged plasma membrane. Members of the annexins A (ANXA) family belong to this protein machinery. ANXA are small soluble proteins, twelve in number in humans, which share the property of binding to membranes exposing negatively-charged phospholipids in the presence of calcium (Ca2+). Many ANXA have been reported to participate in membrane repair of varied cell types and species, including human skeletal muscle cells in which they may play a collective role in protection and repair of the sarcolemma. Here, we discuss the participation of ANXA in membrane repair of healthy skeletal muscle cells and how dysregulation of ANXA expression may impact the clinical severity of muscular dystrophies.

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Have Duchenne Muscular Dystrophy Patients an Increased Cancer Risk?

Journal of Neuromuscular Diseases ◽

10.3233/jnd-210676 ◽

2021 ◽

pp. 1-5

Author(s):

Gian Luca Vita ◽

Luisa Politano ◽

Angela Berardinelli ◽

Giuseppe Vita

Keyword(s):

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Systematic Investigation ◽

Mdx Mice ◽

True Incidence ◽

Patients With Cancer ◽

Dmd Gene ◽

Age Range ◽

Prevalence Of Cancer

Background: Increasing evidence suggests that Duchenne muscular dystrophy (DMD) gene is involved in the occurrence of different types of cancer. Moreover, development of sarcomas was reported in mdx mice, the murine model of DMD, in older age. So far, nine isolated DMD patients were reported with concomitant cancer, four of whom with rhabdomyosarcoma (RMS), but no systematic investigation was performed about the true incidence of cancer in DMD. Methods: All members of the Italian Association of Myology were asked about the occurrence of cancer in their DMD patients in the last 30 years. Results: Four DMD patients with cancer were reported after checking 2455 medical records. One developed brain tumour at the age of 35 years. Two patients had alveolar RMS at 14 and 17 years of age. The fourth patient had a benign enchondroma when 11-year-old. Conclusion: Prevalence of cancer in general in the Italian DMD patients does not seem to be different from that in the general population with the same age range. Although the small numbers herein presented do not allow definitive conclusion, the frequent occurrence of RMS in DMD patients raises an alert for basic researchers and clinicians. The role of DMD gene in cancer merits further investigations.

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Autophagy in the heart is enhanced and independent of disease progression in mus musculus dystrophinopathy models

JRSM Cardiovascular Disease ◽

10.1177/2048004019879581 ◽

2019 ◽

Vol 8 ◽

pp. 204800401987958

Author(s):

HR Spaulding ◽

C Ballmann ◽

JC Quindry ◽

MB Hudson ◽

JT Selsby

Keyword(s):

Skeletal Muscle ◽

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Disease Progression ◽

Gene Mutations ◽

Dystrophin Gene ◽

Mdx Mice ◽

Dystrophin Deficiency ◽

Muscle Wasting Disease ◽

Dystrophin Protein

Background Duchenne muscular dystrophy is a muscle wasting disease caused by dystrophin gene mutations resulting in dysfunctional dystrophin protein. Autophagy, a proteolytic process, is impaired in dystrophic skeletal muscle though little is known about the effect of dystrophin deficiency on autophagy in cardiac muscle. We hypothesized that with disease progression autophagy would become increasingly dysfunctional based upon indirect autophagic markers. Methods Markers of autophagy were measured by western blot in 7-week-old and 17-month-old control (C57) and dystrophic (mdx) hearts. Results Counter to our hypothesis, markers of autophagy were similar between groups. Given these surprising results, two independent experiments were conducted using 14-month-old mdx mice or 10-month-old mdx/Utrn± mice, a more severe model of Duchenne muscular dystrophy. Data from these animals suggest increased autophagosome degradation. Conclusion Together these data suggest that autophagy is not impaired in the dystrophic myocardium as it is in dystrophic skeletal muscle and that disease progression and related injury is independent of autophagic dysfunction.

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Differential Effects of Halofuginone Enantiomers on Muscle Fibrosis and Histopathology in Duchenne Muscular Dystrophy

International Journal of Molecular Sciences ◽

10.3390/ijms22137063 ◽

2021 ◽

Vol 22 (13) ◽

pp. 7063

Author(s):

Sharon Mordechay ◽

Shaun Smullen ◽

Paul Evans ◽

Olga Genin ◽

Mark Pines ◽

...

Keyword(s):

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Motor Coordination ◽

Mdx Mice ◽

Cell Viability Assay ◽

Muscle Fibrosis ◽

Antifibrotic Therapy ◽

Racemic Form ◽

Viability Assay

Progressive loss of muscle and muscle function is associated with significant fibrosis in Duchenne muscular dystrophy (DMD) patients. Halofuginone, an analog of febrifugine, prevents fibrosis in various animal models, including those of muscular dystrophies. Effects of (+)/(−)-halofuginone enantiomers on motor coordination and diaphragm histopathology in mdx mice, the mouse model for DMD, were examined. Four-week-old male mice were treated with racemic halofuginone, or its separate enantiomers, for 10 weeks. Controls were treated with saline. Racemic halofuginone-treated mice demonstrated better motor coordination and balance than controls. However, (+)-halofuginone surpassed the racemic form’s effect. No effect was observed for (−)-halofuginone, which behaved like the control. A significant reduction in collagen content and degenerative areas, and an increase in utrophin levels were observed in diaphragms of mice treated with racemic halofuginone. Again, (+)-halofuginone was more effective than the racemic form, whereas (−)-halofuginone had no effect. Both racemic and (+)-halofuginone increased diaphragm myofiber diameters, with no effect for (−)-halofuginone. No effects were observed for any of the compounds tested in an in-vitro cell viability assay. These results, demonstrating a differential effect of the halofuginone enantiomers and superiority of (+)-halofuginone, are of great importance for future use of (+)-halofuginone as a DMD antifibrotic therapy.

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