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

Author(s):  
H. D. Geissinge ◽  
L.D. Rhodes

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.

Metabolites ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 61 ◽  
Author(s):  
Josiane Joseph ◽  
Dong Cho ◽  
Jason Doles

Duchenne muscular dystrophy (DMD) is a musculoskeletal disorder that causes severe morbidity and reduced lifespan. Individuals with DMD have an X-linked mutation that impairs their ability to produce functional dystrophin protein in muscle. No cure exists for this disease and the few therapies that are available do not dramatically delay disease progression. Thus, there is a need to better understand the mechanisms underlying DMD which may ultimately lead to improved treatment options. The muscular dystrophy (MDX) mouse model is frequently used to explore DMD disease traits. Though some studies of metabolism in dystrophic mice exist, few have characterized metabolic profiles of supporting cells in the diseased environment. Using nontargeted metabolomics we characterized metabolic alterations in muscle satellite cells (SCs) and serum of MDX mice. Additionally, live-cell imaging revealed MDX-derived adipose progenitor cell (APC) defects. Finally, metabolomic studies revealed a striking elevation of acylcarnitines in MDX APCs, which we show can inhibit APC proliferation. Together, these studies highlight widespread metabolic alterations in multiple progenitor cell types and serum from MDX mice and implicate dystrophy-associated metabolite imbalances in APCs as a potential contributor to adipose tissue disequilibrium in DMD.


Author(s):  
Ray Mitchell ◽  
Norman E Frederick ◽  
Emily R Holzman ◽  
Francesca Agobe ◽  
Heather C M Allaway ◽  
...  

Dilated cardiomyopathy contributes to morbidity and mortality in Duchenne Muscular Dystrophy (DMD), an inheritable muscle wasting disease caused by a mutation in the dystrophin gene. Preclinical studies in mouse models of muscular dystrophy have demonstrated reduced cardiomyopathy and improved cardiac function following oral treatment with the potent and selective thromboxane A2/prostanoid receptor (TPr) antagonist, ifetroban. Further, a phase 2 clinical trial (NCT03340675, Cumberland Pharmaceutical) is currently recruiting subjects to determine if ifetroban can improve cardiac function in patients with DMD. Although TPr is a promising therapeutic target for the treatment of dilated cardiomyopathy in DMD, little is known about TPr function in coronary arteries that perfuse blood through the cardiac tissue. In the current study, isolated coronary arteries from young (~3-5 months) and aged (~9-12 months) mdx mice, a widely used mouse model of DMD, and age-matched controls were examined using wire myography. Vasoconstriction to increasing concentrations of TPr agonist U-46619(U4) was enhanced in young mdx mice versus controls. Additionally, young mdx mice displayed a significant attenuation in endothelial cell-mediated vasodilation to increasing concentrations of the muscarinic agonist acetylcholine (ACh). Since TPr activation was enhanced in young mdx mice, U4-mediated vasoconstriction was measured in the absence and presence of ifetroban. Ifetroban reduced U4-mediated vasoconstriction in young mdx and both aged mdx and control mice. Overall, our data demonstrate enhanced coronary arterial vasoconstriction to TPr activation in young mdx mice, a phenotype that could be reversed with ifetroban. These data could have important therapeutic implications for improving cardiovascular function in DMD.


Author(s):  
H.D. Geissinger ◽  
L.D. Rhodes

Since the ‘mdx’ mouse appears to have the same basic defect as sufferers of human Duchenne Muscular Dystrophy (DMD), much recent interest in this possible animal model for the human disease has been generated. Perforations in the sarcolemma have been reported recently in the necrotic tibialis anterior (TA) of 35-days-old and the extensor digitorum longus muscles of 39-days-old ‘mdx’ mice. It is the purpose of this communication to find out if these lesions occur not only in necrotic, but also in unaffected, or in centronucleated fibers of the TA of mice which are younger than 35, or older than 39 days.METHODS: TA from 22-, 25-, 41-, 61- and 99-days-old C57BL/10ScSn/MDX and C57BL/lOScSn control mice were pinned on corkboard in a relaxed state, prefixed for 30 minutes in 2.5% glutaraldehyde followed by routine processing for TEM. Appropriate micrographs were evaluated for a more detailed morphological analysis of the sarcolemma (SL) and the basal lamina (BL).RESULTS: It should be stated beforehand that in all muscles examined the BL appeared to be intact. In the muscles of a 25-days-old control mouse the SL appeared quite intact (FIG. 1). In contrast to this small perforations or large tears in the SL could be seen in otherwise unaffected muscles of 22- (FIG. 2), 25- and 41-days-old ‘mdx’ mice, as well as in necrotic and regenerating fibers of mice from these ages.


2020 ◽  
Author(s):  
◽  
Lakmini P. Wasala

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI-COLUMBIA AT REQUEST OF AUTHOR.] Duchenne Muscular dystrophy (DMD) is the most common, progressive childhood muscular dystrophy with an X-linked inheritance. The major cause of the disease is the mutations in the dystrophin gene which results in the absence of a functional dystrophin protein. Currently there is no permanent cure for DMD. Many genetic and pharmacological approaches have resulted in tremendous improvements in animal models and advanced the mission of finding a permanent cure for DMD. Adeno associated virus (AAV) mediated micro-dystrophin gene therapy is the most promising approach to treat patients irrespective of their type of mutations. Dystrophin independent AAV gene therapies have also shown encouraging data in animal models in subsiding DMD pathology. In engineering micro-dystrophins, it is important to include the most essential regions or domains to achieve maximum benefits, that fits into the AAV. Our goal was to understand the impact of hinge 1 (H1) and hinge 4 (H4) regions in the function of a micro-dystrophin ([micro]Dys) construct. Two novel micro-dystrophins were engineered by complete deletion of either hinge 1 or hinge 4 and packaged in AAV9. Three separate groups of 3-month old male mdx4cv mice tibialis anterior muscles were injected with each novel AAV.[micro]Dys vector and parent vector separately. Three months post injection TA muscle contractile properties were evaluated. Hinge 1 deletion was tolerated by parent [micro]Dys although deletion of hinge 4 reduced the functional performance. Hinge domains played an important part in localization of [micro]Dys to the sarcolemma. Deletion of hinge 1 did not interfere with normal sarcolemmal localization whereas complete deletion of hinge 4 failed to localize [micro]Dys. Both novel [micro]Dys were able to restore dystrophin associated glycoprotein complex (DGC) proteins to the sarcolemma in dystrophin positive fibers. To further analyze which region of hinge 4 that could be devoid of [micro]Dys, we engineered additional four novel [micro]Dys with modifications in only the hinge 4 region, while hinge 1 is intact. Deletion of the region upstream of WW domain was shown to enhance the [micro]Dys function, and any other deletion reduced the performance of [micro]Dys. We also found that deletion of upstream region of WW domain did not interfere in [micro]Dys localization to sarcolemma and other deletions failed to fully restore [micro]Dys to sarcolemma. Next, we developed another micro-dystrophin that combined complete deletion of hinge 1 with deletion of the upstream region of WW domain. This latest [micro]Dys showed to preserve the muscle tetanic force similar to parent [micro]Dys. This is the first study of in-depth evaluation of the importance of the presence or absence of hinge 1 and hinge 4 in the functional performance of micro-dystrophin. These data provide valuable insights in engineering novel micro-dystrophins. One of the major cellular networks affected in DMD is the mitochondrial function and subsequent metabolic homeostasis. PGC-1a is a key transcriptional co-activator of mitochondrial biogenesis and oxidative metabolism in muscle. PGC-1a has previously studied in improving skeletal muscle pathology in mdx mouse model although its therapeutic effects on mdx cardiac pathology has not been evaluated. We delivered AAV9.PGC-1a vector systemically via the tail vein of 12-month old female mdx mice and 4-months post injected we evaluated the left ventricular hemodynamic parameters. AAV.PGC-1a treated mice showed normalization of several left ventricular hemodynamic parameters to the wild type level. Pathway protein analysis revealed overexpression of PGC-1a, resulted in the increased expression of several major transcription factors in oxidative phosphorylation, mitochondrial biogenesis, fatty acid metabolism, electron transport chain. This is the first study to report that cardiac hemodynamic improvements in 4-month treatment of AAV.PGC-1a in aged mdx mice. This study also shows that without replacing dystrophin, PGC-1a overexpression alone resulted in improving cardiac performance by improving cardiac metabolism in mdx mice. The data provided useful insights developing novel therapies in improving DMD cardiomyopathy. In the final study we used another novel isoform of PGC-1a family, PGC-1a4 which has shown to be expressed during resistance training and regulates muscle hypertrophy. As muscle hypertrophy induction has previously shown to be therapeutically effective in mdx mouse model, we delivered AAV.PGC-1a4 systemically and as intramuscular injections. In the mdx4cv mouse model, we could not overexpress the PGC-1a4 protein above the endogenous levels and no cardiac or skeletal muscle function was improved. Although intramuscular delivery of AAV.PGC-1a4 in wild type mice showed overexpression of PGC-1a4 protein above endogenous levels. Wild type mice showed improvements in eccentric force, although muscle cross sectional area or muscle weight did not reach statistical significance. Our study concluded that PGC-1a4 is not a suitable candidate for AAV gene therapy for DMD. In summary, this dissertation provides important discoveries related to development of next-generation micro-dystrophin vectors and dystrophin-independent AAV gene therapies.


2022 ◽  
Vol 23 (2) ◽  
pp. 958
Author(s):  
Marco Ponzetti ◽  
Argia Ucci ◽  
Antonio Maurizi ◽  
Luca Giacchi ◽  
Anna Teti ◽  
...  

Lipocalin 2 (Lcn2) is an adipokine involved in bone and energy metabolism. Its serum levels correlate with bone mechanical unloading and inflammation, two conditions representing hallmarks of Duchenne Muscular Dystrophy (DMD). Therefore, we investigated the role of Lcn2 in bone loss induced by muscle failure in the MDX mouse model of DMD. We found increased Lcn2 serum levels in MDX mice at 1, 3, 6, and 12 months of age. Consistently, Lcn2 mRNA was higher in MDX versus WT muscles. Immunohistochemistry showed Lcn2 expression in mononuclear cells between muscle fibres and in muscle fibres, thus confirming the gene expression results. We then ablated Lcn2 in MDX mice, breeding them with Lcn2−/− mice (MDXxLcn2−/−), resulting in a higher percentage of trabecular volume/total tissue volume compared to MDX mice, likely due to reduced bone resorption. Moreover, MDXxLcn2−/− mice presented with higher grip strength, increased intact muscle fibres, and reduced serum creatine kinase levels compared to MDX. Consistently, blocking Lcn2 by treating 2-month-old MDX mice with an anti-Lcn2 monoclonal antibody (Lcn2Ab) increased trabecular volume, while reducing osteoclast surface/bone surface compared to MDX mice treated with irrelevant IgG. Grip force was also increased, and diaphragm fibrosis was reduced by the Lcn2Ab. These results suggest that Lcn2 could be a possible therapeutic target to treat DMD-induced bone loss.


2021 ◽  
Author(s):  
Madison Feng ◽  
Sara Mata Lopez ◽  
Soraya Manaviazar ◽  
Hamish A. Watson ◽  
Karl Hale ◽  
...  

<p>(-)-Agelastatin A (AA) in 1,2-propanediol (3-deoxy-DL-glycerol) elicits a dose-dependent decrease in OPN mRNA expression in canine Duchenne Muscular Dystrophy (DMD) myoblasts at doses ranging from 0.01 nM-30 nM. When intraperitoneally administered in the same vehicle to mdx mice at 2.5 mg/kg/day for two weeks, and at 1.5 mg/kg/day twice-weekly for two weeks, (-)-AA brings about a significant decrease in exercise-induced muscle damage through its attenuation of OPN expression. Because (-)-AA is known to downregulate OPN, this study confirms that the use of small molecule OPN downregulatory drugs can beneficially modify the phenotype in DMD animal models and potentially affected boys</p>


2021 ◽  
Vol 23 (1) ◽  
pp. 470
Author(s):  
Olga Mucha ◽  
Katarzyna Kaziród ◽  
Paulina Podkalicka ◽  
Kinga Rusin ◽  
Józef Dulak ◽  
...  

Dysregulation of autophagy may contribute to the progression of various muscle diseases, including Duchenne muscular dystrophy (DMD). Heme oxygenase-1 (HO-1, encoded by Hmox1), a heme-degrading enzyme, may alleviate symptoms of DMD, inter alia, through anti-inflammatory properties. In the present study, we determined the role of HO-1 in the regulation of autophagy and mitophagy in mdx animals, a commonly used mouse model of the disease. In the gastrocnemius of 6-week-old DMD mice, the mRNA level of mitophagy markers: Bnip3 and Pink1, as well as autophagy regulators, e.g., Becn1, Map1lc3b, Sqstm1, and Atg7, was decreased. In the dystrophic diaphragm, changes in the latter were less prominent. In older, 12-week-old dystrophic mice, diminished expressions of Pink1 and Sqstm1 with upregulation of Atg5, Atg7, and Lamp1 was depicted. Interestingly, we demonstrated higher protein levels of autophagy regulator, LC3, in dystrophic muscles. Although the lack of Hmox1 in mdx mice influenced blood cell count and the abundance of profibrotic proteins, no striking differences in mRNA and protein levels of autophagy and mitophagy markers were found. In conclusion, we demonstrated complex, tissue, and age-dependent dysregulation of mitophagic and autophagic markers in DMD mice, which are not affected by the additional lack of Hmox1.


2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Steven Carberry ◽  
Margit Zweyer ◽  
Dieter Swandulla ◽  
Kay Ohlendieck

X-linked muscular dystrophy is a highly progressive disease of childhood and characterized by primary genetic abnormalities in the dystrophin gene. Senescent mdx specimens were used for a large-scale survey of potential age-related alterations in the dystrophic phenotype, because the established mdx animal model of dystrophinopathy exhibits progressive deterioration of muscle tissue with age. Since the mdxtibialis anteriormuscle is a frequently used model system in muscular dystrophy research, we employed this particular muscle to determine global changes in the dystrophic skeletal muscle proteome. The comparison of mdx mice aged 8 weeks versus 22 months by mass-spectrometry-based proteomics revealed altered expression levels in 8 distinct protein species. Increased levels were shown for carbonic anhydrase, aldolase, and electron transferring flavoprotein, while the expressions of pyruvate kinase, myosin, tropomyosin, and the small heat shock protein Hsp27 were found to be reduced in aged muscle. Immunoblotting confirmed age-dependent changes in the density of key muscle proteins in mdx muscle. Thus, segmental necrosis in mdxtibialis anteriormuscle appears to trigger age-related protein perturbations due to dystrophin deficiency. The identification of novel indicators of progressive muscular dystrophy might be useful for the establishment of a muscle subtype-specific biomarker signature of dystrophinopathy.


2021 ◽  
Author(s):  
Madison Feng ◽  
Sara Mata Lopez ◽  
Soraya Manaviazar ◽  
Hamish A. Watson ◽  
Karl Hale ◽  
...  

<p>(-)-Agelastatin A (AA) in 1,2-propanediol (3-deoxy-DL-glycerol) elicits a dose-dependent decrease in OPN mRNA expression in canine Duchenne Muscular Dystrophy (DMD) myoblasts at doses ranging from 0.01 nM-30 nM. When intraperitoneally administered in the same vehicle to mdx mice at 2.5 mg/kg/day for two weeks, and at 1.5 mg/kg/day twice-weekly for two weeks, (-)-AA brings about a significant decrease in exercise-induced muscle damage through its attenuation of OPN expression. Because (-)-AA is known to downregulate OPN, this study confirms that the use of small molecule OPN downregulatory drugs can beneficially modify the phenotype in DMD animal models and potentially affected boys</p>


2019 ◽  
Vol 28 (20) ◽  
pp. 3369-3390 ◽  
Author(s):  
Nurit Yanay ◽  
Moran Elbaz ◽  
Jenya Konikov-Rozenman ◽  
Sharona Elgavish ◽  
Yuval Nevo ◽  
...  

Abstract Congenital muscular dystrophy type-1A (Lama2-CMD) and Duchenne muscular dystrophy (DMD) result from deficiencies of laminin-α2 and dystrophin proteins, respectively. Although both proteins strengthen the sarcolemma, they are implicated in clinically distinct phenotypes. We used RNA-deep sequencing (RNA-Seq) of dy2J/dy2J, Lama2-CMD mouse model, skeletal muscle at 8 weeks of age to elucidate disease pathophysiology. This study is the first report of dy2J/dy2J model whole transcriptome profile. RNA-Seq of the mdx mouse model of DMD and wild-type (WT) mouse was carried as well in order to enable a novel comparison of dy2J/dy2J to mdx. A large group of shared differentially expressed genes (DEGs) was found in dy2J/dy2J and mdx models (1834 common DEGs, false discovery rate [FDR] < 0.05). Enrichment pathway analysis using ingenuity pathway analysis showed enrichment of inflammation, fibrosis, cellular movement, migration and proliferation of cells, apoptosis and necrosis in both mouse models (P-values 3E-10–9E-37). Via canonical pathway analysis, actin cytoskeleton, integrin, integrin-linked kinase, NF-kB, renin–angiotensin, epithelial–mesenchymal transition, and calcium signaling were also enriched and upregulated in both models (FDR < 0.05). Interestingly, significant downregulation of Pax7 was detected in dy2J/dy2J compared to upregulation of this key regeneration gene in mdx mice. Pax3 and Mamstr genes were also downregulated in dy2J/dy2J compared to WT mice. These results may explain the distinct disease course and severity in these models. While the mdx model at that stage shows massive regeneration, the dy2J/dy2J shows progressive dystrophic process. Our data deepen our understanding of the molecular pathophysiology and suggest new targets for additional therapies to upregulate regeneration in Lama2-CMD.


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