Overexpression of the cytotoxic T cell GalNAc transferase in skeletal muscle inhibits muscular dystrophy in mdx mice

The cytotoxic T cell (CT) GalNAc transferase, or Galgt2, is a UDP-GalNAc:β1,4- N-acetylgalactosaminyltransferase that is localized to the neuromuscular synapse in adult skeletal muscle, where it creates the synaptic CT carbohydrate antigen {GalNAcβ1,4[NeuAc(orGc)α2, 3]Galβ1,4GlcNAcβ-}. Overexpression of Galgt2 in the skeletal muscles of transgenic mice inhibits the development of muscular dystrophy in mdx mice, a model for Duchenne muscular dystrophy. Here, we provide physiological evidence as to how Galgt2 may inhibit the development of muscle pathology in mdx animals. Both Galgt2 transgenic wild-type and mdx skeletal muscles showed a marked improvement in normalized isometric force during repetitive eccentric contractions relative to nontransgenic littermates, even using a paradigm where nontransgenic muscles had force reductions of 95% or more. Muscles from Galgt2 transgenic mice, however, showed a significant decrement in normalized specific force and in hindlimb and forelimb grip strength at some ages. Overexpression of Galgt2 in muscles of young adult mdx mice, where Galgt2 has no effect on muscle size, also caused a significant decrease in force drop during eccentric contractions and increased normalized specific force. A comparison of Galgt2 and microdystrophin overexpression using a therapeutically relevant intravascular gene delivery protocol showed Galgt2 was as effective as microdystrophin at preventing loss of force during eccentric contractions. These experiments provide a mechanism to explain why Galgt2 overexpression inhibits muscular dystrophy in mdx muscles. That overexpression also prevents loss of force in nondystrophic muscles suggests that Galgt2 is a therapeutic target with broad potential applications.

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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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Lmo7 is dispensable for skeletal muscle and cardiac function

AJP Cell Physiology ◽

10.1152/ajpcell.00177.2015 ◽

2015 ◽

Vol 309 (7) ◽

pp. C470-C479 ◽

Cited By ~ 6

Author(s):

Dieu Hung Lao ◽

Mary C. Esparza ◽

Shannon N. Bremner ◽

Indroneal Banerjee ◽

Jianlin Zhang ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscular Dystrophy ◽

Cardiac Function ◽

Cardiac Muscle ◽

Mapk Pathway ◽

Mdx Mouse ◽

Mdx Mice ◽

Mouse Line

Emery-Dreifuss muscular dystrophy (EDMD) is a degenerative disease primarily affecting skeletal muscles in early childhood as well as cardiac muscle at later stages. EDMD is caused by a number of mutations in genes encoding proteins associated with the nuclear envelope (e.g., Emerin, Lamin A/C, and Nesprin). Recently, a novel protein, Lim-domain only 7 ( lmo7) has been reported to play a role in the molecular pathogenesis of EDMD. Prior in vitro and in vivo studies suggested the intriguing possibility that Lmo7 plays a role in skeletal or cardiac muscle pathophysiology. To further understand the in vivo role of Lmo7 in striated muscles, we generated a novel Lmo7-null ( lmo7−/−) mouse line. Using this mouse line, we examined skeletal and cardiac muscle physiology, as well as the role of Lmo7 in a model of muscular dystrophy and regeneration using the dystrophin-deficient mdx mouse model. Our results demonstrated that lmo7−/− mice had no abnormalities in skeletal muscle morphology, physiological function, or regeneration. Cardiac function was also unaffected. Moreover, we found that ablation of lmo7 in mdx mice had no effect on the observed myopathy and muscular regeneration exhibited by mdx mice. Molecular analyses also showed no changes in dystrophin complex factors, MAPK pathway components, and Emerin levels in lmo7 knockout mice. Taken together, we conclude that Lmo7 is dispensable for skeletal muscle and cardiac physiology and pathophysiology.

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Flk-1+ Adipose-Derived Mesenchymal Stem Cells Differentiate into Skeletal Muscle Satellite Cells and Ameliorate Muscular Dystrophy in MDX Mice

Stem Cells and Development ◽

10.1089/scd.2006.0118 ◽

2007 ◽

Vol 16 (5) ◽

pp. 695-706 ◽

Cited By ~ 90

Author(s):

Yanning Liu ◽

Xi Yan ◽

Zhao Sun ◽

Bin Chen ◽

Qin Han ◽

...

Keyword(s):

Skeletal Muscle ◽

Stem Cells ◽

Mesenchymal Stem Cells ◽

Muscular Dystrophy ◽

Satellite Cells ◽

Mdx Mice ◽

Muscle Satellite Cells ◽

Skeletal Muscle Satellite Cells

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

The Journal of General Physiology ◽

10.1085/jgp.201110738 ◽

2012 ◽

Vol 139 (3) ◽

pp. 209-218 ◽

Cited By ~ 20

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.

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Overexpression of the Cytotoxic T Cell (CT) Carbohydrate Inhibits Muscular Dystrophy in the dyW Mouse Model of Congenital Muscular Dystrophy 1A

American Journal Of Pathology ◽

10.2353/ajpath.2007.060927 ◽

2007 ◽

Vol 171 (1) ◽

pp. 181-199 ◽

Cited By ~ 40

Author(s):

Rui Xu ◽

Kumaran Chandrasekharan ◽

Jung Hae Yoon ◽

Marybeth Camboni ◽

Paul T. Martin

Keyword(s):

T Cell ◽

Muscular Dystrophy ◽

Mouse Model ◽

Congenital Muscular Dystrophy ◽

Cytotoxic T Cell

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Nutraceutical and pharmaceutical cocktails did not improve muscle function or reduce histological damage in D2-mdx mice

Journal of Applied Physiology ◽

10.1152/japplphysiol.00162.2019 ◽

2019 ◽

Vol 127 (4) ◽

pp. 1058-1066

Author(s):

Hannah R. Spaulding ◽

Tiffany Quindry ◽

Kayleen Hammer ◽

John C. Quindry ◽

Joshua T. Selsby

Keyword(s):

Skeletal Muscle ◽

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Muscle Function ◽

Sirtuin 1 ◽

Mdx Mice ◽

Limb Muscle ◽

Nicotinamide Riboside ◽

Histological Damage ◽

Dystrophin Deficiency

Progressive muscle injury and weakness are hallmarks of Duchenne muscular dystrophy. We showed previously that quercetin (Q) partially protected dystrophic limb muscles from disease-related injury. As quercetin activates PGC-1α through Sirtuin-1, an NAD+-dependent deacetylase, the depleted NAD+ in dystrophic skeletal muscle may limit quercetin efficacy; hence, supplementation with the NAD+ donor, nicotinamide riboside (NR), may facilitate quercetin efficacy. Lisinopril (Lis) protects skeletal muscle and improves cardiac function in dystrophin-deficient mice; therefore, it was included in this study to evaluate the effects of lisinopril used with quercetin and NR. Our purpose was to determine the extent to which Q, NR, and Lis decreased dystrophic injury. We hypothesized that Q, NR, or Lis alone would improve muscle function and decrease histological injury and when used in combination would have additive effects. Muscle function of 11-mo-old DBA (healthy), D2-mdx (dystrophin-deficient), and D2-mdx mice was assessed after treatment with Q, NR, and/or Lis for 7 mo. To mimic typical pharmacology of patients with Duchenne muscular dystrophy, a group was treated with prednisolone (Pred) in combination with Q, NR, and Lis. At 11 mo of age, dystrophin deficiency decreased specific tension and tetanic force in the soleus and extensor digitorum longus muscles and was not corrected by any treatment. Dystrophic muscle was more sensitive to contraction-induced injury, which was partially offset in the QNRLisPred group, whereas fatigue was similar between all groups. Treatments did not decrease histological damage. These data suggest that treatment with Q, NR, Lis, and Pred failed to adequately maintain dystrophic limb muscle function or decrease histological damage. NEW & NOTEWORTHY Despite a compelling rationale and previous evidence to the contrary in short-term investigations, quercetin, nicotinamide riboside, or Lisinopril, alone or in combination, failed to restore muscle function or decrease histological injury in dystrophic limb muscle from D2-mdx mice after long-term administration. Importantly, we also found that in the D2-mdx model, an emerging and relatively understudied model of Duchenne muscular dystrophy dystrophin deficiency caused profound muscle dysfunction and histopathology in skeletal muscle.

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Defective dystrophic thymus determines degenerative changes in skeletal muscle

Nature Communications ◽

10.1038/s41467-021-22305-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Andrea Farini ◽

Clementina Sitzia ◽

Chiara Villa ◽

Barbara Cassani ◽

Luana Tripodi ◽

...

Keyword(s):

Skeletal Muscle ◽

T Cells ◽

Muscular Dystrophy ◽

Inflammatory Cells ◽

Regulatory Control ◽

Mdx Mice ◽

Specific Response ◽

Molecular Pattern ◽

Cellular Debris ◽

Tnf Α

AbstractIn Duchenne muscular dystrophy (DMD), sarcolemma fragility and myofiber necrosis produce cellular debris that attract inflammatory cells. Macrophages and T-lymphocytes infiltrate muscles in response to damage-associated molecular pattern signalling and the release of TNF-α, TGF-β and interleukins prevent skeletal muscle improvement from the inflammation. This immunological scenario was extended by the discovery of a specific response to muscle antigens and a role for regulatory T cells (Tregs) in muscle regeneration. Normally, autoimmunity is avoided by autoreactive T-lymphocyte deletion within thymus, while in the periphery Tregs monitor effector T-cells escaping from central regulatory control. Here, we report impairment of thymus architecture of mdx mice together with decreased expression of ghrelin, autophagy dysfunction and AIRE down-regulation. Transplantation of dystrophic thymus in recipient nude mice determine the up-regulation of inflammatory/fibrotic markers, marked metabolic breakdown that leads to muscle atrophy and loss of force. These results indicate that involution of dystrophic thymus exacerbates muscular dystrophy by altering central immune tolerance.

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A Comparative Study of N-glycolylneuraminic Acid (Neu5Gc) and Cytotoxic T Cell (CT) Carbohydrate Expression in Normal and Dystrophin-Deficient Dog and Human Skeletal Muscle

PLoS ONE ◽

10.1371/journal.pone.0088226 ◽

2014 ◽

Vol 9 (2) ◽

pp. e88226 ◽

Cited By ~ 6

Author(s):

Paul T. Martin ◽

Bethannie Golden ◽

Jonathan Okerblom ◽

Marybeth Camboni ◽

Kumaran Chandrasekharan ◽

...

Keyword(s):

Skeletal Muscle ◽

T Cell ◽

Comparative Study ◽

Human Skeletal Muscle ◽

Cytotoxic T Cell

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Abstract 252: The Capsaicin Sensitive Afferent Neuron Innervating Skeletal Muscle is Abnormal in the Mdx Mouse

Circulation Research ◽

10.1161/res.121.suppl_1.252 ◽

2017 ◽

Vol 121 (suppl_1) ◽

Author(s):

Qinglu Li ◽

Mary Garry

Keyword(s):

Blood Pressure ◽

Skeletal Muscle ◽

Muscular Dystrophy ◽

Blood Pressure Response ◽

Dystrophin Gene ◽

Mdx Mouse ◽

Mdx Mice ◽

Afferent Neuron ◽

Afferent Neurons ◽

Left Common Iliac Artery

Duchenne muscular dystrophy (DMD) is a severe type of muscular dystrophy caused by a mutation of the dystrophin gene at locus Xp21, located on the short arm of the X chromosome. Muscle wasting and weakness are common in DMD and in the murine mdx model. We previously demonstrated Group III and IV afferent neurons, which innervate skeletal muscle and control blood pressure and heart rate in response to exercise, are abnormal in settings of ischemia and atrophy; such as cardiomyopathy. We hypothesized that these afferent neurons would also display abnormalities in the mdx mouse. To test this hypothesis, we developed a decerebrate mouse model using 10 wk and 6 mo old male BL10 WT and MDX mice to test mean arterial pressure (MAP) responses to intra-arterial capsaicin (IA-Cap; a specific stimulant of group IV afferent neurons). Mice were anesthetized and MAP was continuously recorded with a pressure transducer in the left carotid artery after which the animal was rendered decerebrate. Following decerebration, anesthesia was discontinued and IA-Cap (0,003-1ug/100ul) was delivered via the left common iliac artery. In rats, we have demonstrated this to be a valid model for evaluating MAP responses to activation of metabolically active afferent neurons. We observed that MAP increased in a dose-related fashion in both 10wk and 6 mo old WT and MDX, while 10 wk old MDX mouse had a normal response, the 6 months MDX mouse response was significantly blunted when compared to WT. To test whether these abnormalities are related to the onset of cardiomyopathy, Echocardiography was performed using 6 months old BL10 WT and MDX mice, no abnormality was found in terms of LV dimensions and function in MDX mice comparing with WT mice. Further studies will be performed to determine whether these abnormalities are inherent to changes in the skeletal muscle of the mdx mouse. We conclude that this murine model displays pressor responses to IA-Cap, similar to the rat and that MDX mice have a blunted blood pressure response to IA-Cap. These results indicate that abnormalities exist within the skeletal muscle afferent neurons in the mdx model.

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