1
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Jama A, Alshudukhi AA, Burke S, Dong L, Kamau JK, Voss AA, Ren H. Lipin1 plays complementary roles in myofibre stability and regeneration in dystrophic muscles. J Physiol 2023; 601:961-978. [PMID: 36715084 PMCID: PMC9992338 DOI: 10.1113/jp284085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 01/23/2023] [Indexed: 01/31/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a severe muscle wasting disorder caused by dystrophin mutations, leading to the loss of sarcolemmal integrity, and resulting in progressive myofibre necrosis and impaired muscle function. Our previous studies suggest that lipin1 is important for skeletal muscle regeneration and myofibre integrity. Additionally, we discovered that mRNA expression levels of lipin1 were significantly reduced in skeletal muscle of DMD patients and the mdx mouse model. To understand the role of lipin1 in dystrophic muscle, we generated dystrophin/lipin1 double knockout (DKO) mice, and compared the limb muscle pathology and function of wild-type B10, muscle-specific lipin1 deficient (lipin1Myf5cKO ), mdx and DKO mice. We found that further knockout of lipin1 in dystrophic muscle exhibited a more severe phenotype characterized by increased necroptosis, fibrosis and exacerbated membrane damage in DKO compared to mdx mice. In barium chloride-induced muscle injury, both lipin1Myf5cKO and DKO showed prolonged regeneration at day 14 post-injection, suggesting that lipin1 is critical for muscle regeneration. In situ contractile function assays showed that lipin1 deficiency in dystrophic muscle led to reduced specific force production. Using a cell culture system, we found that lipin1 deficiency led to elevated expression levels of necroptotic markers and medium creatine kinase, which could be a result of sarcolemmal damage. Most importantly, restoration of lipin1 inhibited the elevation of necroptotic markers in differentiated primary lipin1-deficient myoblasts. Overall, our data suggests that lipin1 plays complementary roles in myofibre stability and muscle function in dystrophic muscles, and overexpression of lipin1 may serve as a potential therapeutic strategy for dystrophic muscles. KEY POINTS: We identified that lipin1 mRNA expression levels are significantly reduced in skeletal muscles of Duchenne muscular dystrophy patients and mdx mice. We found that further depletion of lipin1 in skeletal muscles of mdx mice induces more severe dystrophic phenotypes, including enhanced myofibre sarcolemma damage, muscle necroptosis, inflammation, fibrosis and reduced specific force production. Lipin1 deficiency leads to elevated expression levels of necroptotic markers, whereas restoration of lipin1 inhibits their expression. Our results suggest that lipin1 is functionally complementary to dystrophin in muscle membrane integrity and muscle regeneration.
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Affiliation(s)
- Abdulrahman Jama
- Department of Biochemistry and Molecular Biology, Wright State University, Dayton, OH, USA
| | - Abdullah A. Alshudukhi
- Department of Biochemistry and Molecular Biology, Wright State University, Dayton, OH, USA
| | - Steve Burke
- Department of Biological Sciences, Wright State University, Dayton, OH, USA
| | - Lixin Dong
- Mumetel LLC, University Technology Park at IIT, Chicago, IL, USA
| | - John Karanja Kamau
- Department of Biochemistry and Molecular Biology, Wright State University, Dayton, OH, USA
| | - Andrew Alvin Voss
- Department of Biological Sciences, Wright State University, Dayton, OH, USA
| | - Hongmei Ren
- Department of Biochemistry and Molecular Biology, Wright State University, Dayton, OH, USA
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2
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Valenzuela IMPY, Chen PJ, Barden J, Kosloski O, Akaaboune M. Distinct roles of the dystrophin-glycoprotein complex: α-dystrobrevin and α-syntrophin in the maintenance of the postsynaptic apparatus of the neuromuscular synapse. Hum Mol Genet 2022; 31:2370-2385. [PMID: 35157076 PMCID: PMC9307313 DOI: 10.1093/hmg/ddac041] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/25/2022] [Accepted: 02/09/2022] [Indexed: 02/02/2023] Open
Abstract
α-syntrophin (α-syn) and α-dystrobrevin (α-dbn), two components of the dystrophin-glycoprotein complex, are essential for the maturation and maintenance of the neuromuscular junction (NMJ) and mice deficient in either α-syn or α-dbn exhibit similar synaptic defects. However, the functional link between these two proteins and whether they exert distinct or redundant functions in the postsynaptic organization of the NMJ remain largely unknown. We generated and analyzed the synaptic phenotype of double heterozygote (α-dbn+/-, α-syn+/-), and double homozygote knockout (α-dbn-/-; α-syn-/-) mice and examined the ability of individual molecules to restore their defects in the synaptic phenotype. We showed that in double heterozygote mice, NMJs have normal synaptic phenotypes and no signs of muscular dystrophy. However, in double knockout mice (α-dbn-/-; α-syn-/-), the synaptic phenotype (the density, the turnover and the distribution of AChRs within synaptic branches) is more severely impaired than in single α-dbn-/- or α-syn-/- mutants. Furthermore, double mutant and single α-dbn-/- mutant mice showed more severe exercise-induced fatigue and more significant reductions in grip strength than single α-syn-/- mutant and wild-type. Finally, we showed that the overexpression of the transgene α-syn-GFP in muscles of double mutant restores primarily the abnormal extensions of membrane containing AChRs that extend beyond synaptic gutters and lack synaptic folds, whereas the overexpression of α-dbn essentially restores the abnormal dispersion of patchy AChR aggregates in the crests of synaptic folds. Altogether, these data suggest that α-syn and α-dbn act in parallel pathways and exert distinct functions on the postsynaptic structural organization of NMJs.
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Affiliation(s)
| | - Po-Ju Chen
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Joseph Barden
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Olivia Kosloski
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Mohammed Akaaboune
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
- Program in Neuroscience, University of Michigan, Ann Arbor, MI, USA
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3
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Abstract
The limb-girdle muscular dystrophies (LGMD) are a collection of genetic diseases united in their phenotypical expression of pelvic and shoulder area weakness and wasting. More than 30 subtypes have been identified, five dominant and 26 recessive. The increase in the characterization of new genotypes in the family of LGMDs further adds to the heterogeneity of the disease. Meanwhile, better understanding of the phenotype led to the reconsideration of the disease definition, which resulted in eight old subtypes to be no longer recognized officially as LGMD and five new diseases to be added to the LGMD family. The unique variabilities of LGMD stem from genetic mutations, which then lead to protein and ultimately muscle dysfunction. Herein, we review the LGMD pathway, starting with the genetic mutations that encode proteins involved in muscle maintenance and repair, and including the genotype–phenotype relationship of the disease, the epidemiology, disease progression, burden of illness, and emerging treatments.
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4
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Dombernowsky NW, Ölmestig JNE, Witting N, Kruuse C. Role of neuronal nitric oxide synthase (nNOS) in Duchenne and Becker muscular dystrophies - Still a possible treatment modality? Neuromuscul Disord 2018; 28:914-926. [PMID: 30352768 DOI: 10.1016/j.nmd.2018.09.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 08/07/2018] [Accepted: 09/05/2018] [Indexed: 02/08/2023]
Abstract
Neuronal nitric oxide synthase (nNOS) is involved in nitric oxide (NO) production and suggested to play a crucial role in blood flow regulation of skeletal muscle. During activation of the muscle, NO helps attenuate the sympathetic vasoconstriction to accommodate increased metabolic demands, a phenomenon known as functional sympatholysis. In inherited myopathies such as the dystrophinopathies Duchenne and Becker muscle dystrophies (DMD and BMD), nNOS is lost from the sarcolemma. The loss of nNOS may cause functional ischemia contributing to skeletal and cardiac muscle cell injury. Effects of NO is augmented by inhibiting degradation of the second messenger cyclic guanosine monophosphate (cGMP) using sildenafil and tadalafil, both of which inhibit the enzyme phosphodiesterase 5 (PDE5). In animal models of DMD, PDE5-inhibitors prevent functional ischemia, reduce post-exercise skeletal muscle pathology and fatigue, show amelioration of cardiac muscle cell damage and increase cardiac performance. However, effect on clinical outcomes in DMD and BMD patients have been disappointing with minor effects on upper limb performance and none on ambulation. This review aims to summarize the current knowledge of nNOS function related to functional sympatholysis in skeletal muscle and studies on PDE5-inhibitor treatment in nNOS-deficient animal models and patients.
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Affiliation(s)
- Nanna W Dombernowsky
- Department of Neurology, Rigshospitalet Glostrup, University of Copenhagen, Denmark
| | - Joakim N E Ölmestig
- Department of Neurology, Neurovascular Research Unit, Herlev Gentofte Hospital, University of Copenhagen, Denmark
| | - Nanna Witting
- Department of Neurology, Rigshospitalet Glostrup, University of Copenhagen, Denmark
| | - Christina Kruuse
- Department of Neurology, Neurovascular Research Unit, Herlev Gentofte Hospital, University of Copenhagen, Denmark; PDE Research Group, Lundbeck Foundation Center for Neurovascular Research (LUCENS), Denmark.
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5
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Heydemann A. Skeletal Muscle Metabolism in Duchenne and Becker Muscular Dystrophy-Implications for Therapies. Nutrients 2018; 10:nu10060796. [PMID: 29925809 PMCID: PMC6024668 DOI: 10.3390/nu10060796] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 06/14/2018] [Accepted: 06/16/2018] [Indexed: 02/06/2023] Open
Abstract
The interactions between nutrition and metabolism and skeletal muscle have long been known. Muscle is the major metabolic organ—it consumes more calories than other organs—and therefore, there is a clear need to discuss these interactions and provide some direction for future research areas regarding muscle pathologies. In addition, new experiments and manuscripts continually reveal additional highly intricate, reciprocal interactions between metabolism and muscle. These reciprocal interactions include exercise, age, sex, diet, and pathologies including atrophy, hypoxia, obesity, diabetes, and muscle myopathies. Central to this review are the metabolic changes that occur in the skeletal muscle cells of muscular dystrophy patients and mouse models. Many of these metabolic changes are pathogenic (inappropriate body mass changes, mitochondrial dysfunction, reduced adenosine triphosphate (ATP) levels, and increased Ca2+) and others are compensatory (increased phosphorylated AMP activated protein kinase (pAMPK), increased slow fiber numbers, and increased utrophin). Therefore, reversing or enhancing these changes with therapies will aid the patients. The multiple therapeutic targets to reverse or enhance the metabolic pathways will be discussed. Among the therapeutic targets are increasing pAMPK, utrophin, mitochondrial number and slow fiber characteristics, and inhibiting reactive oxygen species. Because new data reveals many additional intricate levels of interactions, new questions are rapidly arising. How does muscular dystrophy alter metabolism, and are the changes compensatory or pathogenic? How does metabolism affect muscular dystrophy? Of course, the most profound question is whether clinicians can therapeutically target nutrition and metabolism for muscular dystrophy patient benefit? Obtaining the answers to these questions will greatly aid patients with muscular dystrophy.
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Affiliation(s)
- Ahlke Heydemann
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA.
- Center for Cardiovascular Research, The University of Illinois at Chicago, Chicago, IL 60612, USA.
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6
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Lopez JR, Uryash A, Kolster J, Estève E, Zhang R, Adams JA. Enhancing Endogenous Nitric Oxide by Whole Body Periodic Acceleration Elicits Neuroprotective Effects in Dystrophic Neurons. Mol Neurobiol 2018; 55:8680-8694. [DOI: 10.1007/s12035-018-1018-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Accepted: 03/16/2018] [Indexed: 12/25/2022]
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7
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Smith LR, Barton ER. Regulation of fibrosis in muscular dystrophy. Matrix Biol 2018; 68-69:602-615. [PMID: 29408413 DOI: 10.1016/j.matbio.2018.01.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 01/15/2018] [Accepted: 01/16/2018] [Indexed: 02/08/2023]
Abstract
The production of force and power are inherent properties of skeletal muscle, and regulated by contractile proteins within muscle fibers. However, skeletal muscle integrity and function also require strong connections between muscle fibers and their extracellular matrix (ECM). A well-organized and pliant ECM is integral to muscle function and the ability for many different cell populations to efficiently migrate through ECM is critical during growth and regeneration. For many neuromuscular diseases, genetic mutations cause disruption of these cytoskeletal-ECM connections, resulting in muscle fragility and chronic injury. Ultimately, these changes shift the balance from myogenic pathways toward fibrogenic pathways, culminating in the loss of muscle fibers and their replacement with fatty-fibrotic matrix. Hence a common pathological hallmark of muscular dystrophy is prominent fibrosis. This review will cover the salient features of muscular dystrophy pathogenesis, highlight the signals and cells that are important for myogenic and fibrogenic actions, and discuss how fibrosis alters the ECM of skeletal muscle, and the consequences of fibrosis in developing therapies.
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Affiliation(s)
- Lucas R Smith
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA, United States
| | - Elisabeth R Barton
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, United States.
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8
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Sakellariou GK, McDonagh B. Redox Homeostasis in Age-Related Muscle Atrophy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1088:281-306. [PMID: 30390257 DOI: 10.1007/978-981-13-1435-3_13] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Muscle atrophy and weakness, characterized by loss of lean muscle mass and function, has a significant effect on the independence and quality of life of older people. The cellular mechanisms that drive the age-related decline in neuromuscular integrity and function are multifactorial. Quiescent and contracting skeletal muscle can endogenously generate reactive oxygen and nitrogen species (RONS) from various cellular sites. Excessive RONS can potentially cause oxidative damage and disruption of cellular signaling pathways contributing to the initiation and progression of age-related muscle atrophy. Altered redox homeostasis and modulation of intracellular signal transduction processes have been proposed as an underlying mechanism of sarcopenia. This chapter summarizes the current evidence that has associated disrupted redox homeostasis and muscle atrophy as a result of skeletal muscle inactivity and aging.
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Affiliation(s)
| | - Brian McDonagh
- Discipline of Physiology, School of Medicine, NUI Galway, Galway, Ireland
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9
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Sakellariou GK, Lightfoot AP, Earl KE, Stofanko M, McDonagh B. Redox homeostasis and age-related deficits in neuromuscular integrity and function. J Cachexia Sarcopenia Muscle 2017; 8:881-906. [PMID: 28744984 PMCID: PMC5700439 DOI: 10.1002/jcsm.12223] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 04/06/2017] [Accepted: 05/22/2017] [Indexed: 12/25/2022] Open
Abstract
Skeletal muscle is a major site of metabolic activity and is the most abundant tissue in the human body. Age-related muscle atrophy (sarcopenia) and weakness, characterized by progressive loss of lean muscle mass and function, is a major contributor to morbidity and has a profound effect on the quality of life of older people. With a continuously growing older population (estimated 2 billion of people aged >60 by 2050), demand for medical and social care due to functional deficits, associated with neuromuscular ageing, will inevitably increase. Despite the importance of this 'epidemic' problem, the primary biochemical and molecular mechanisms underlying age-related deficits in neuromuscular integrity and function have not been fully determined. Skeletal muscle generates reactive oxygen and nitrogen species (RONS) from a variety of subcellular sources, and age-associated oxidative damage has been suggested to be a major factor contributing to the initiation and progression of muscle atrophy inherent with ageing. RONS can modulate a variety of intracellular signal transduction processes, and disruption of these events over time due to altered redox control has been proposed as an underlying mechanism of ageing. The role of oxidants in ageing has been extensively examined in different model organisms that have undergone genetic manipulations with inconsistent findings. Transgenic and knockout rodent studies have provided insight into the function of RONS regulatory systems in neuromuscular ageing. This review summarizes almost 30 years of research in the field of redox homeostasis and muscle ageing, providing a detailed discussion of the experimental approaches that have been undertaken in murine models to examine the role of redox regulation in age-related muscle atrophy and weakness.
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Affiliation(s)
| | - Adam P. Lightfoot
- School of Healthcare ScienceManchester Metropolitan UniversityManchesterM1 5GDUK
| | - Kate E. Earl
- MRC‐Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic DiseaseUniversity of LiverpoolLiverpoolL7 8TXUK
| | - Martin Stofanko
- Microvisk Technologies LtdThe Quorum7600 Oxford Business ParkOxfordOX4 2JZUK
| | - Brian McDonagh
- MRC‐Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, Department of Musculoskeletal Biology, Institute of Ageing and Chronic DiseaseUniversity of LiverpoolLiverpoolL7 8TXUK
- Department of Physiology, School of MedicineNational University of IrelandGalwayIreland
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10
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Timpani CA, Hayes A, Rybalka E. Therapeutic strategies to address neuronal nitric oxide synthase deficiency and the loss of nitric oxide bioavailability in Duchenne Muscular Dystrophy. Orphanet J Rare Dis 2017; 12:100. [PMID: 28545481 PMCID: PMC5445371 DOI: 10.1186/s13023-017-0652-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 05/12/2017] [Indexed: 12/25/2022] Open
Abstract
Duchenne Muscular Dystrophy is a rare and fatal neuromuscular disease in which the absence of dystrophin from the muscle membrane induces a secondary loss of neuronal nitric oxide synthase and the muscles capacity for endogenous nitric oxide synthesis. Since nitric oxide is a potent regulator of skeletal muscle metabolism, mass, function and regeneration, the loss of nitric oxide bioavailability is likely a key contributor to the chronic pathological wasting evident in Duchenne Muscular Dystrophy. As such, various therapeutic interventions to re-establish either the neuronal nitric oxide synthase protein deficit or the consequential loss of nitric oxide synthesis and bioavailability have been investigated in both animal models of Duchenne Muscular Dystrophy and in human clinical trials. Notably, the efficacy of these interventions are varied and not always translatable from animal model to human patients, highlighting a complex interplay of factors which determine the downstream modulatory effects of nitric oxide. We review these studies herein.
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Affiliation(s)
- Cara A Timpani
- College of Health & Biomedicine, Victoria University, PO Box 14428, Melbourne, Victoria, Australia, 8001.,Australian Institute for Musculoskeletal Science (AIMSS), Melbourne, Victoria, 3021, Australia
| | - Alan Hayes
- College of Health & Biomedicine, Victoria University, PO Box 14428, Melbourne, Victoria, Australia, 8001.,Institute of Sport, Exercise & Active Living (ISEAL), Victoria University, Melbourne, Victoria, 8001, Australia.,Australian Institute for Musculoskeletal Science (AIMSS), Melbourne, Victoria, 3021, Australia
| | - Emma Rybalka
- College of Health & Biomedicine, Victoria University, PO Box 14428, Melbourne, Victoria, Australia, 8001. .,Institute of Sport, Exercise & Active Living (ISEAL), Victoria University, Melbourne, Victoria, 8001, Australia. .,Australian Institute for Musculoskeletal Science (AIMSS), Melbourne, Victoria, 3021, Australia.
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11
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Timpani CA, Trewin AJ, Stojanovska V, Robinson A, Goodman CA, Nurgali K, Betik AC, Stepto N, Hayes A, McConell GK, Rybalka E. Attempting to Compensate for Reduced Neuronal Nitric Oxide Synthase Protein with Nitrate Supplementation Cannot Overcome Metabolic Dysfunction but Rather Has Detrimental Effects in Dystrophin-Deficient mdx Muscle. Neurotherapeutics 2017; 14:429-446. [PMID: 27921261 PMCID: PMC5398978 DOI: 10.1007/s13311-016-0494-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Duchenne muscular dystrophy arises from the loss of dystrophin and is characterized by calcium dysregulation, muscular atrophy, and metabolic dysfunction. The secondary reduction of neuronal nitric oxide synthase (nNOS) from the sarcolemma reduces NO production and bioavailability. As NO modulates glucose uptake, metabolism, and mitochondrial bioenergetics, we investigated whether an 8-week nitrate supplementation regimen could overcome metabolic dysfunction in the mdx mouse. Dystrophin-positive control (C57BL/10) and dystrophin-deficient mdx mice were supplemented with sodium nitrate (85 mg/l) in drinking water. Following the supplementation period, extensor digitorum longus and soleus were excised and radioactive glucose uptake was measured at rest (basal) and during contraction. Gastrocnemius was excised and mitochondrial respiration was measured using the Oroboros Oxygraph. Tibialis anterior was analyzed immunohistochemically for the presence of dystrophin, nNOS, nitrotyrosine, IgG and CD45+ cells, and histologically to assess areas of damage and regeneration. Glucose uptake in the basal and contracting states was normal in unsupplemented mdx muscles but was reduced following nitrate supplementation in mdx muscles only. The mitochondrial utilization of substrates was also impaired in mdx gastrocnemius during phosphorylating and maximal uncoupled respiration, and nitrate could not improve respiration in mdx muscle. Although nitrate supplementation reduced mitochondrial hydrogen peroxide emission, it induced mitochondrial uncoupling in red gastrocnemius, increased muscle fiber peroxynitrite (nitrotyrosine), and promoted skeletal muscle damage. Our novel data suggest that despite lower nNOS protein expression and likely lower NO production in mdx muscle, enhancing NO production with nitrate supplementation in these mice has detrimental effects on skeletal muscle. This may have important relevance for those with DMD.
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Affiliation(s)
- Cara A Timpani
- Centre for Chronic Disease, College of Health & Biomedicine, Victoria University, Melbourne, Victoria, 8001, Australia
| | - Adam J Trewin
- Institute of Sport, Exercise & Active Living (ISEAL), Victoria University, Melbourne, Victoria, 8001, Australia
| | - Vanesa Stojanovska
- Centre for Chronic Disease, College of Health & Biomedicine, Victoria University, Melbourne, Victoria, 8001, Australia
| | - Ainsley Robinson
- Centre for Chronic Disease, College of Health & Biomedicine, Victoria University, Melbourne, Victoria, 8001, Australia
| | - Craig A Goodman
- Centre for Chronic Disease, College of Health & Biomedicine, Victoria University, Melbourne, Victoria, 8001, Australia
- Institute of Sport, Exercise & Active Living (ISEAL), Victoria University, Melbourne, Victoria, 8001, Australia
- Australian Institute of Musculoskeletal Science (AIMSS), Western Health, Melbourne, Victoria, 3021, Australia
| | - Kulmira Nurgali
- Centre for Chronic Disease, College of Health & Biomedicine, Victoria University, Melbourne, Victoria, 8001, Australia
| | - Andrew C Betik
- Centre for Chronic Disease, College of Health & Biomedicine, Victoria University, Melbourne, Victoria, 8001, Australia
- Institute of Sport, Exercise & Active Living (ISEAL), Victoria University, Melbourne, Victoria, 8001, Australia
| | - Nigel Stepto
- Institute of Sport, Exercise & Active Living (ISEAL), Victoria University, Melbourne, Victoria, 8001, Australia
| | - Alan Hayes
- Centre for Chronic Disease, College of Health & Biomedicine, Victoria University, Melbourne, Victoria, 8001, Australia
- Institute of Sport, Exercise & Active Living (ISEAL), Victoria University, Melbourne, Victoria, 8001, Australia
- Australian Institute of Musculoskeletal Science (AIMSS), Western Health, Melbourne, Victoria, 3021, Australia
| | - Glenn K McConell
- Institute of Sport, Exercise & Active Living (ISEAL), Victoria University, Melbourne, Victoria, 8001, Australia
- Australian Institute of Musculoskeletal Science (AIMSS), Western Health, Melbourne, Victoria, 3021, Australia
| | - Emma Rybalka
- Centre for Chronic Disease, College of Health & Biomedicine, Victoria University, Melbourne, Victoria, 8001, Australia.
- Institute of Sport, Exercise & Active Living (ISEAL), Victoria University, Melbourne, Victoria, 8001, Australia.
- Australian Institute of Musculoskeletal Science (AIMSS), Western Health, Melbourne, Victoria, 3021, Australia.
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12
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Woodman KG, Coles CA, Lamandé SR, White JD. Nutraceuticals and Their Potential to Treat Duchenne Muscular Dystrophy: Separating the Credible from the Conjecture. Nutrients 2016; 8:E713. [PMID: 27834844 PMCID: PMC5133099 DOI: 10.3390/nu8110713] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 10/20/2016] [Accepted: 11/04/2016] [Indexed: 12/20/2022] Open
Abstract
In recent years, complementary and alternative medicine has become increasingly popular. This trend has not escaped the Duchenne Muscular Dystrophy community with one study showing that 80% of caregivers have provided their Duchenne patients with complementary and alternative medicine in conjunction with their traditional treatments. These statistics are concerning given that many supplements are taken based on purely "anecdotal" evidence. Many nutraceuticals are thought to have anti-inflammatory or anti-oxidant effects. Given that dystrophic pathology is exacerbated by inflammation and oxidative stress these nutraceuticals could have some therapeutic benefit for Duchenne Muscular Dystrophy (DMD). This review gathers and evaluates the peer-reviewed scientific studies that have used nutraceuticals in clinical or pre-clinical trials for DMD and thus separates the credible from the conjecture.
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MESH Headings
- Animals
- Anti-Inflammatory Agents, Non-Steroidal/adverse effects
- Anti-Inflammatory Agents, Non-Steroidal/therapeutic use
- Antioxidants/adverse effects
- Antioxidants/therapeutic use
- Biomedical Research/methods
- Biomedical Research/trends
- Combined Modality Therapy/adverse effects
- Dietary Supplements/adverse effects
- Evidence-Based Medicine
- Humans
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/physiopathology
- Muscular Dystrophy, Duchenne/diet therapy
- Muscular Dystrophy, Duchenne/metabolism
- Muscular Dystrophy, Duchenne/physiopathology
- Muscular Dystrophy, Duchenne/therapy
- Peer Review, Research/methods
- Peer Review, Research/trends
- Reproducibility of Results
- Severity of Illness Index
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Affiliation(s)
- Keryn G Woodman
- Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville 3052, Australia.
- Faculty of Veterinary and Agricultural Science, The University of Melbourne, Parkville 3010, Australia.
| | - Chantal A Coles
- Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville 3052, Australia.
| | - Shireen R Lamandé
- Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville 3052, Australia.
- Department of Pediatrics, The University of Melbourne, Parkville 3010, Australia.
| | - Jason D White
- Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville 3052, Australia.
- Faculty of Veterinary and Agricultural Science, The University of Melbourne, Parkville 3010, Australia.
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13
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Allen DG, Whitehead NP, Froehner SC. Absence of Dystrophin Disrupts Skeletal Muscle Signaling: Roles of Ca2+, Reactive Oxygen Species, and Nitric Oxide in the Development of Muscular Dystrophy. Physiol Rev 2016; 96:253-305. [PMID: 26676145 DOI: 10.1152/physrev.00007.2015] [Citation(s) in RCA: 272] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Dystrophin is a long rod-shaped protein that connects the subsarcolemmal cytoskeleton to a complex of proteins in the surface membrane (dystrophin protein complex, DPC), with further connections via laminin to other extracellular matrix proteins. Initially considered a structural complex that protected the sarcolemma from mechanical damage, the DPC is now known to serve as a scaffold for numerous signaling proteins. Absence or reduced expression of dystrophin or many of the DPC components cause the muscular dystrophies, a group of inherited diseases in which repeated bouts of muscle damage lead to atrophy and fibrosis, and eventually muscle degeneration. The normal function of dystrophin is poorly defined. In its absence a complex series of changes occur with multiple muscle proteins showing reduced or increased expression or being modified in various ways. In this review, we will consider the various proteins whose expression and function is changed in muscular dystrophies, focusing on Ca(2+)-permeable channels, nitric oxide synthase, NADPH oxidase, and caveolins. Excessive Ca(2+) entry, increased membrane permeability, disordered caveolar function, and increased levels of reactive oxygen species are early changes in the disease, and the hypotheses for these phenomena will be critically considered. The aim of the review is to define the early damage pathways in muscular dystrophy which might be appropriate targets for therapy designed to minimize the muscle degeneration and slow the progression of the disease.
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Affiliation(s)
- David G Allen
- Sydney Medical School & Bosch Institute, University of Sydney, New South Wales, Australia; and Department of Physiology & Biophysics, University of Washington, Seattle, Washington
| | - Nicholas P Whitehead
- Sydney Medical School & Bosch Institute, University of Sydney, New South Wales, Australia; and Department of Physiology & Biophysics, University of Washington, Seattle, Washington
| | - Stanley C Froehner
- Sydney Medical School & Bosch Institute, University of Sydney, New South Wales, Australia; and Department of Physiology & Biophysics, University of Washington, Seattle, Washington
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14
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Rebolledo DL, Kim MJ, Whitehead NP, Adams ME, Froehner SC. Sarcolemmal targeting of nNOSμ improves contractile function of mdx muscle. Hum Mol Genet 2015; 25:158-66. [PMID: 26604149 DOI: 10.1093/hmg/ddv466] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 11/09/2015] [Indexed: 11/13/2022] Open
Abstract
Nitric oxide (NO) is a key regulator of skeletal muscle function and metabolism, including vasoregulation, mitochondrial function, glucose uptake, fatigue and excitation-contraction coupling. The main generator of NO in skeletal muscle is the muscle-specific form of neuronal nitric oxide synthase (nNOSμ) produced by the NOS1 gene. Skeletal muscle nNOSμ is predominantly localized at the sarcolemma by interaction with the dystrophin protein complex (DPC). In Duchenne muscular dystrophy (DMD), loss of dystrophin leads to the mislocalization of nNOSμ from the sarcolemma to the cytosol. This perturbation has been shown to impair contractile function and cause muscle fatigue in dystrophic (mdx) mice. Here, we investigated the effect of restoring sarcolemmal nNOSμ on muscle contractile function in mdx mice. To achieve this, we designed a modified form of nNOSμ (NOS-M) that is targeted to the sarcolemma by palmitoylation, even in the absence of the DPC. When expressed specifically in mdx skeletal muscle, NOS-M significantly attenuates force loss owing to damaging eccentric contractions and repetitive isometric contractions (fatigue), while also improving force recovery after fatigue. Expression of unmodified nNOSμ at similar levels does not lead to sarcolemmal association and fails to improve muscle function. Aside from the benefits of sarcolemmal-localized NO production, NOS-M also increased the surface membrane levels of utrophin and other DPC proteins, including β-dystroglycan, α-syntrophin and α-dystrobrevin in mdx muscle. These results suggest that the expression of NOS-M in skeletal muscle may be therapeutically beneficial in DMD and other muscle diseases characterized by the loss of nNOSμ from the sarcolemma.
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Affiliation(s)
- Daniela L Rebolledo
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195-7290, USA and Departamento de Biología Celular y Molecular, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
| | - Min Jeong Kim
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195-7290, USA and
| | - Nicholas P Whitehead
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195-7290, USA and
| | - Marvin E Adams
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195-7290, USA and
| | - Stanley C Froehner
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195-7290, USA and
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15
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Nelson MD, Rosenberry R, Barresi R, Tsimerinov EI, Rader F, Tang X, Mason O, Schwartz A, Stabler T, Shidban S, Mobaligh N, Hogan S, Elashoff R, Allen JD, Victor RG. Sodium nitrate alleviates functional muscle ischaemia in patients with Becker muscular dystrophy. J Physiol 2015; 593:5183-200. [PMID: 26437761 DOI: 10.1113/jp271252] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 09/21/2015] [Indexed: 12/26/2022] Open
Abstract
Becker muscular dystrophy (BMD) is a progressive X-linked muscle wasting disease for which there is no treatment. BMD is caused by in-frame mutations in the gene encoding dystrophin, a structural cytoskeletal protein that also targets other proteins to the sarcolemma. Among these is neuronal nitric oxide synthase mu (nNOSμ), which requires specific spectrin-like repeats (SR16/17) in dystrophin's rod domain and the adaptor protein α-syntrophin for sarcolemmal targeting. When healthy skeletal muscle is exercised, sarcolemmal nNOSμ-derived nitric oxide (NO) attenuates α-adrenergic vasoconstriction, thus optimizing perfusion. In the mdx mouse model of dystrophinopathy, this protective mechanism (functional sympatholysis) is defective, resulting in functional muscle ischaemia. Treatment with a NO-donating non-steroidal anti-inflammatory drug (NSAID) alleviates this ischaemia and improves the murine dystrophic phenotype. In the present study, we report that, in 13 men with BMD, sympatholysis is defective mainly in patients whose mutations disrupt sarcolemmal targeting of nNOSμ, with the vasoconstrictor response measured as a decrease in muscle oxygenation (near infrared spectroscopy) to reflex sympathetic activation. Then, in a single-arm, open-label trial in 11 BMD patients and a double-blind, placebo-controlled cross-over trial in six patients, we show that acute treatment with oral sodium nitrate, an inorganic NO donor without a NSIAD moiety, restores sympatholysis and improves post-exercise hyperaemia (Doppler ultrasound). By contrast, sodium nitrate improves neither sympatholysis, nor hyperaemia in healthy controls. Thus, a simple NO donor recapitulates the vasoregulatory actions of sarcolemmal nNOS in BMD patients, and constitutes a putative novel therapy for this disease.
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Affiliation(s)
- Michael D Nelson
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Ryan Rosenberry
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Rita Barresi
- NSCT Diagnostic & Advisory Service for Rare Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle upon Tyne, UK
| | | | - Florian Rader
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Xiu Tang
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - O'Neil Mason
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Avery Schwartz
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Thomas Stabler
- Duke Institute of Molecular Physiology, Duke University Medical Centre, Durham, NC, USA
| | - Sarah Shidban
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Neigena Mobaligh
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Shomari Hogan
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Robert Elashoff
- Department of Biomathematics, University of California Los Angeles, Los Angeles, CA, USA
| | - Jason D Allen
- Clinical Exercise Science Program, Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, VIC, Australia
| | - Ronald G Victor
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
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16
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Sciorati C, Clementi E, Manfredi AA, Rovere-Querini P. Fat deposition and accumulation in the damaged and inflamed skeletal muscle: cellular and molecular players. Cell Mol Life Sci 2015; 72:2135-56. [PMID: 25854633 PMCID: PMC11113943 DOI: 10.1007/s00018-015-1857-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 02/09/2015] [Accepted: 02/11/2015] [Indexed: 12/16/2022]
Abstract
The skeletal muscle has the capacity to repair damage by the activation and differentiation of fiber sub-laminar satellite cells. Regeneration impairment due to reduced satellite cells number and/or functional capacity leads to fiber substitution with ectopic tissues including fat and fibrous tissue and to the loss of muscle functions. Muscle mesenchymal cells that in physiological conditions sustain or directly contribute to regeneration differentiate in adipocytes in patients with persistent damage and inflammation of the skeletal muscle. These cells comprise the fibro-adipogenic precursors, the PW1-expressing cells and some interstitial cells associated with vessels (pericytes, mesoangioblasts and myoendothelial cells). Resident fibroblasts that are responsible for collagen deposition and extracellular matrix remodeling during regeneration yield fibrotic tissue and can differentiate into adipose cells. Some authors have also proposed that satellite cells themselves could transdifferentiate into adipocytes, although recent results by lineage tracing techniques seem to put this theory to discussion. This review summarizes findings about muscle resident mesenchymal cell differentiation in adipocytes and recapitulates the molecular mediators involved in intramuscular adipose tissue deposition.
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Affiliation(s)
- Clara Sciorati
- Division of Regenerative Medicine, Stem Cells and Gene Therapy, San Raffaele Scientific Institute, via Olgettina 58, 20132, Milan, Italy,
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17
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Cordani N, Pisa V, Pozzi L, Sciorati C, Clementi E. Nitric oxide controls fat deposition in dystrophic skeletal muscle by regulating fibro-adipogenic precursor differentiation. Stem Cells 2015; 32:874-85. [PMID: 24170326 DOI: 10.1002/stem.1587] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 09/05/2013] [Indexed: 01/24/2023]
Abstract
Duchenne muscular dystrophy (DMD) is an hereditary disease characterized by loss of muscle fibers and their progressive substitution by fat and fibrous tissue. Mesenchymal fibro-adipogenic progenitors (FAPs) expressing the platelet-derived growth factor receptor alpha (PDGFRα) are an important source of fibrosis and adipogenesis in dystrophic skeletal muscle. Among the therapies suggested for dystrophy are those based on nitric oxide (NO) donating drugs, the administration of which slows disease progression. NO has been shown to act by enhancing the regenerative potential of the diseased muscle. Whether it acts also by inhibiting fibrosis and adipogenesis was not known. Here, we show in vitro that NO regulates FAP fate through inhibition of their differentiation into adipocytes. In mdx mice, an animal model of DMD, treatment with the NO donating drug molsidomine reduced the number of PDGFRα(+) cells as well as the deposition of both skeletal muscle fat and connective tissues. Inhibition of adipogenesis was due to NO-induced increased expression of miR-27b leading to downregulation of peroxisome proliferator-activated receptors gamma (Pparγ1) expression in a pathway independent of cGMP generation. These findings reveal an additional effect of NO in dystrophic muscle that conceivably synergizes with its known effects on regeneration improvement and explain why NO-based therapies appear effective in the treatment of muscular dystrophy.
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Affiliation(s)
- Nicoletta Cordani
- Scientific Institute, IRCCS E. Medea 23842 Bosisio Parini, Lecco, Italy
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18
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Lawler JM, Kunst M, Hord JM, Lee Y, Joshi K, Botchlett RE, Ramirez A, Martinez DA. EUK-134 ameliorates nNOSμ translocation and skeletal muscle fiber atrophy during short-term mechanical unloading. Am J Physiol Regul Integr Comp Physiol 2014; 306:R470-82. [PMID: 24477538 DOI: 10.1152/ajpregu.00371.2013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Reduced mechanical loading during bedrest, spaceflight, and casting, causes rapid morphological changes in skeletal muscle: fiber atrophy and reduction of slow-twitch fibers. An emerging signaling event in response to unloading is the translocation of neuronal nitric oxide synthase (nNOSμ) from the sarcolemma to the cytosol. We used EUK-134, a cell-permeable mimetic of superoxide dismutase and catalase, to test the role of redox signaling in nNOSμ translocation and muscle fiber atrophy as a result of short-term (54 h) hindlimb unloading. Fischer-344 rats were divided into ambulatory control, hindlimb-unloaded (HU), and hindlimb-unloaded + EUK-134 (HU-EUK) groups. EUK-134 mitigated the unloading-induced phenotype, including muscle fiber atrophy and muscle fiber-type shift from slow to fast. nNOSμ immunolocalization at the sarcolemma of the soleus was reduced with HU, while nNOSμ protein content in the cytosol increased with unloading. Translocation of nNOS from the sarcolemma to cytosol was virtually abolished by EUK-134. EUK-134 also mitigated dephosphorylation at Thr-32 of FoxO3a during HU. Hindlimb unloading elevated oxidative stress (4-hydroxynonenal) and increased sarcolemmal localization of Nox2 subunits gp91phox (Nox2) and p47phox, effects normalized by EUK-134. Thus, our findings are consistent with the hypothesis that oxidative stress triggers nNOSμ translocation from the sarcolemma and FoxO3a dephosphorylation as an early event during mechanical unloading. Thus, redox signaling may serve as a biological switch for nNOS to initiate morphological changes in skeletal muscle fibers.
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Affiliation(s)
- John M Lawler
- Redox Biology and Cell Signaling Laboratory, Department of Health and Kinesiology, Texas A&M University, College Station, Texas
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19
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Thomas GD. Functional muscle ischemia in Duchenne and Becker muscular dystrophy. Front Physiol 2013; 4:381. [PMID: 24391598 PMCID: PMC3866652 DOI: 10.3389/fphys.2013.00381] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 12/04/2013] [Indexed: 11/14/2022] Open
Abstract
Duchenne and Becker muscular dystrophy (DMD/BMD) comprise a spectrum of devastating X-linked muscle wasting disease for which there is no treatment. DMD/BMD is caused by mutations in the gene encoding dystrophin, a cytoskeletal protein that stabilizes the muscle membrane and also targets other proteins to the sarcolemma. Among these is the muscle-specific isoform of neuronal nitric oxide synthase (nNOSμ) which binds spectrin-like repeats within dystrophin's rod domain and the adaptor protein α-syntrophin. Dystrophin deficiency causes loss of sarcolemmal nNOSμ and reduces paracrine signaling of muscle-derived nitric oxide (NO) to the microvasculature, which renders the diseased muscle fibers susceptible to functional muscle ischemia during exercise. Repeated bouts of functional ischemia superimposed on muscle fibers already weakened by dystrophin deficiency result in use-dependent focal muscle injury. Genetic and pharmacologic strategies to boost nNOSμ-NO signaling in dystrophic muscle alleviate functional muscle ischemia and show promise as novel therapeutic interventions for the treatment of DMD/BMD.
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Affiliation(s)
- Gail D Thomas
- Heart and Vascular Institute, Penn State College of Medicine Hershey, PA, USA
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20
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Wang G, Lu Q. A Nitrate Ester of Sedative Alkyl Alcohol Improves Muscle Function and Structure in a Murine Model of Duchenne Muscular Dystrophy. Mol Pharm 2013; 10:3862-70. [DOI: 10.1021/mp400310r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Guqi Wang
- McColl-Lockwood
Laboratory, Carolinas Medical Center, Charlotte, North Carolina 28232, United
States
| | - Qilong Lu
- McColl-Lockwood
Laboratory, Carolinas Medical Center, Charlotte, North Carolina 28232, United
States
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21
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Matsakas A, Yadav V, Lorca S, Narkar V. Muscle ERRγ mitigates Duchenne muscular dystrophy via metabolic and angiogenic reprogramming. FASEB J 2013; 27:4004-16. [PMID: 23781095 DOI: 10.1096/fj.13-228296] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Treatment of Duchenne muscular dystrophy (DMD) by replacing mutant dystrophin or restoring dystrophin-associated glycoprotein complex (DAG) has been clinically challenging. Instead, identifying and targeting muscle pathways deregulated in DMD will provide new therapeutic avenues. We report that the expression of nuclear receptor estrogen-related receptor-γ (ERRγ), and its metabolic and angiogenic targets are down-regulated (50-85%) in skeletal muscles of mdx mice (DMD model) vs. wild-type mice. Corelatively, oxidative myofibers, muscle vasculature, and exercise tolerance (33%) are decreased in mdx vs. wild-type mice. Overexpressing ERRγ selectively in the dystrophic muscles of the mdx mice restored metabolic and angiogenic gene expression compared with control mdx mice. Further, ERRγ enhanced muscle oxidative myofibers, vasculature, and blood flow (by 33-66%) and improved exercise tolerance (by 75%) in the dystrophic mice. Restoring muscle ERRγ pathway ameliorated muscle damage and also prevented DMD hallmarks of postexercise muscle damage, hypoxia, and fatigue in mdx mice. Notably, ERRγ did not restore sarcolemmal DAG complex, which is thus dispensable for antidystrophic effects of ERRγ. In summary, ERRγ-dependent metabolic and angiogenic gene program is defective in DMD, and we demonstrate that its restoration is a potential strategy for treating muscular dystrophy.
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Affiliation(s)
- Antonios Matsakas
- 1Center for Metabolic and Degenerative Diseases, Brown Foundation Institute of Molecular Medicine, University of Texas Medical School at Houston, IMM/SRB 430F, 1825 Pressler St., Houston, TX 77030, USA.
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22
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Contribution of oxidative stress to pathology in diaphragm and limb muscles with Duchenne muscular dystrophy. J Muscle Res Cell Motil 2012; 34:1-13. [DOI: 10.1007/s10974-012-9330-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 10/18/2012] [Indexed: 11/27/2022]
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23
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Abstract
The extracellular matrix (ECM) provides a solid scaffold and signals to cells through ECM receptors. The cell-matrix interactions are crucial for normal biological processes and when disrupted they may lead to pathological processes. In particular, the biological importance of ECM-cell membrane-cytoskeleton interactions in skeletal muscle is accentuated by the number of inherited muscle diseases caused by mutations in proteins conferring these interactions. In this review we introduce laminins, collagens, dystroglycan, integrins, dystrophin and sarcoglycans. Mutations in corresponding genes cause various forms of muscular dystrophy. The muscle disorders are presented as well as advances toward the development of treatment.
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Affiliation(s)
- Virginie Carmignac
- Muscle Biology Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden
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24
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25
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Lawler JM. Exacerbation of pathology by oxidative stress in respiratory and locomotor muscles with Duchenne muscular dystrophy. J Physiol 2011; 589:2161-70. [PMID: 21486793 PMCID: PMC3098695 DOI: 10.1113/jphysiol.2011.207456] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Accepted: 03/02/2011] [Indexed: 12/15/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is the most devastating type of muscular dystrophy, leading to progressive weakness of respiratory (e.g. diaphragm) and locomotor muscles (e.g. gastrocnemius). DMD is caused by X-linked defects in the gene that encodes for dystrophin, a key scaffolding protein of the dystroglycan complex (DCG) within the sarcolemmal cytoskeleton. As a result of a compromised dystroglycan complex, mechanical integrity is impaired and important signalling proteins (e.g. nNOS, caveolin-3) and pathways are disrupted. Disruption of the dystroglycan complex leads to high susceptibility to injury with repeated, eccentric contractions as well as inflammation, resulting in significant damage and necrosis. Chronic damage and repair cycling leads to fibrosis and weakness. While the link between inflammation with damage and weakness in the DMD diaphragm is unresolved, elevated oxidative stress may contribute to damage, weakness and possibly fibrosis. While utilization of non-specific antioxidant interventions has yielded inconsistent results, recent data suggest that NAD(P)H oxidase could play a pivotal role in elevating oxidative stress via integrated changes in caveolin-3 and stretch-activated channels (SACs). Oxidative stress may act as an amplifier, exacerbating disruption of the dystroglycan complex, upregulation of the inflammatory transcription factor NF-B, and thus functional impairment of force-generating capacity.
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Affiliation(s)
- John M Lawler
- Department of Health and Kinesiology, Texas A&M University, College Station, TX 77843-4243, USA.
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26
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Percival JM, Adamo CM, Beavo JA, Froehner SC. Evaluation of the therapeutic utility of phosphodiesterase 5A inhibition in the mdx mouse model of duchenne muscular dystrophy. Handb Exp Pharmacol 2011:323-44. [PMID: 21695647 DOI: 10.1007/978-3-642-17969-3_14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Duchenne muscular dystrophy (DMD) is a devastating and ultimately fatal disease characterized by progressive muscle wasting and weakness. DMD is caused by the absence of a functional dystrophin protein, which in turn leads to reduced expression and mislocalization of dystrophin-associated proteins including neuronal nitric oxide (NO) synthase mu (nNOSμ). Disruption of nNOSμ signaling results in muscle fatigue and unopposed sympathetic vasoconstriction during exercise, thereby increasing contraction-induced damage in dystrophin-deficient muscles. The loss of normal nNOSμ signaling during exercise is central to the vascular dysfunction proposed over 40 years ago to be an important pathogenic mechanism in DMD. Recent preclinical studies focused on circumventing defective nNOSμ signaling in dystrophic skeletal and cardiac muscle by inhibiting phosphodiesterase 5A (PDE5A) have shown promising results. This review addresses nNOS signaling in normal and dystrophin-deficient muscles and the potential of PDE5A inhibition as a therapeutic approach for the treatment of cardiovascular deficits in DMD.
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Affiliation(s)
- Justin M Percival
- Department of Physiology and Biophysics, University of Washington, 357290, 98195-7290, Seattle, WA, USA.
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27
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Abstract
The muscular dystrophies are a group of neuromuscular disorders associated with muscle weakness and wasting, which in many forms can lead to loss of ambulation and premature death. A number of muscular dystrophies are associated with loss of proteins required for the maintenance of muscle membrane integrity, in particular with proteins that comprise the dystrophin-associated glycoprotein (DAG) complex. Proper glycosylation of O-linked mannose chains on alpha-dystroglycan, a DAG member, is required for the binding of the extracellular matrix to dystroglycan and for proper DAG function. A number of congenital disorders of glycosylation have now been described where alpha-dystroglycan glycosylation is altered and where muscular dystrophy is a predominant phenotype. Glycosylation is also increasingly being appreciated as a genetic modifier of disease phenotypes in many forms of muscular dystrophy and as a target for the development of new therapies. Here we will review the mouse models available for the study of this group of diseases and outline the methodologies required to describe disease phenotypes.
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28
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Wehling-Henricks M, Oltmann M, Rinaldi C, Myung KH, Tidball JG. Loss of positive allosteric interactions between neuronal nitric oxide synthase and phosphofructokinase contributes to defects in glycolysis and increased fatigability in muscular dystrophy. Hum Mol Genet 2009; 18:3439-51. [PMID: 19542095 DOI: 10.1093/hmg/ddp288] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) involves a complex pathophysiology that is not easily explained by the loss of the protein dystrophin, the primary defect in DMD. Instead, many features of the pathology are attributable to the secondary loss of neuronal nitric oxide synthase (nNOS) from dystrophin-deficient muscle. In this investigation, we tested whether the loss of nNOS contributes to the increased fatigability of mdx mice, a model of DMD. Our findings show that the expression of a muscle-specific, nNOS transgene increases the endurance of mdx mice and enhances glycogen metabolism during treadmill-running, but did not affect vascular perfusion of muscles. We also find that the specific activity of phosphofructokinase (PFK; the rate limiting enzyme in glycolysis) is positively affected by nNOS in muscle; PFK-specific activity is significantly reduced in mdx muscles and the muscles of nNOS null mutants, but significantly increased in nNOS transgenic muscles and muscles from mdx mice that express the nNOS transgene. PFK activity measured under allosteric conditions was significantly increased by nNOS, but unaffected by endothelial NOS or inducible NOS. The specific domain of nNOS that positively regulates PFK activity was assayed by cloning and expressing different domains of nNOS and assaying their effects on PFK activity. This approach yielded a polypeptide that included the flavin adenine dinucleotide (FAD)-binding domain of nNOS as the region of the molecule that promotes PFK activity. Smaller peptides in this domain were then synthesized and used in activity assays that showed a 36-amino acid peptide in the FAD-binding domain in which most of the positive allosteric activity of nNOS for PFK resides. Mapping this peptide onto the structure of nNOS shows that the peptide is exposed on the surface, readily available for binding. Collectively, these findings indicate that defects in glycolytic metabolism and increased fatigability in dystrophic muscle may be caused in part by the loss of positive allosteric interactions between nNOS and PFK.
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Affiliation(s)
- Michelle Wehling-Henricks
- Department of Physiological Science, David Geffen School of Medicine, University of California, Los Angeles, CA 90095-1606, USA
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29
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Colussi C, Gurtner A, Rosati J, Illi B, Ragone G, Piaggio G, Moggio M, Lamperti C, D'Angelo G, Clementi E, Minetti G, Mozzetta C, Antonini A, Capogrossi MC, Puri PL, Gaetano C. Nitric oxide deficiency determines global chromatin changes in Duchenne muscular dystrophy. FASEB J 2009; 23:2131-41. [PMID: 19264835 DOI: 10.1096/fj.08-115618] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The present study provides evidence that abnormal patterns of global histone modification are present in the skeletal muscle nuclei of mdx mice and Duchenne muscular dystrophy (DMD) patients. A combination of specific histone H3 modifications, including Ser-10 phosphorylation, acetylation of Lys 9 and 14, and Lys 79 methylation, were found enriched in muscle biopsies from human patients affected by DMD and in late-term fetuses, early postnatal pups, or adult mdx mice. In this context, chromatin immunoprecipitation experiments showed an enrichment of these modifications at the loci of genes involved in proliferation or inflammation, suggesting a regulatory effect on gene expression. Remarkably, the reexpression of dystrophin induced by gentamicin treatment or the administration of nitric oxide (NO) donors reversed the abnormal pattern of H3 histone modifications. These findings suggest an unanticipated link between the dystrophin-activated NO signaling and the remodeling of chromatin. In this context, the regulation of class IIa histone deacetylases (HDACs) 4 and 5 was found altered as a consequence of the reduced NO-dependent protein phosphatase 2A activity, indicating that both NO and class IIa HDACs are important for satellite cell differentiation and gene expression in mdx mice. In conclusion, this work provides the first evidence of a role for NO as an epigenetic regulator in DMD.
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Affiliation(s)
- Claudia Colussi
- Laboratorio di Terapia Genica e Biologia Vascolare, Istituto Cardiologico Monzino, Milan, Italy
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30
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The dynamics of the nitric oxide release-transient from stretched muscle cells. Int J Biochem Cell Biol 2009; 41:625-31. [DOI: 10.1016/j.biocel.2008.07.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Revised: 07/12/2008] [Accepted: 07/16/2008] [Indexed: 11/20/2022]
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31
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Hall JE, Kaczor JJ, Hettinga BP, Isfort RJ, Tarnopolsky MA. Effects of a CRF2R agonist and exercise on mdx and wildtype skeletal muscle. Muscle Nerve 2007; 36:336-41. [PMID: 17503504 DOI: 10.1002/mus.20820] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Corticotrophin-releasing factor 2 receptor (CRF2R) agonists prevent muscle atrophy due to immobilization, denervation, and corticosteroid-induced muscle atrophy in wildtype mice. We hypothesized that a CRF2R agonist will increase skeletal muscle mass in mdx mice. Mdx (C57BL/10ScSn-Dmd(mdx)) and wildtype (C57BL/6) mice were divided into four groups: sedentary placebo, sedentary CRF2R agonist, exercised placebo, and exercised CRF2R agonist. Mice exercised on a treadmill twice weekly for 30 min (8-12 m/min, 8 weeks). Muscle and heart weights, serum creatine kinase, and gamma-glutamyltransferase activities were measured. The CRF2R agonist increased extensor digitorum longus and soleus muscle weights (P < 0.05) in wildtype and mdx mice. Sedentary mdx CRF2R and exercised mdx placebo mice had lower serum creatine kinase activity than sedentary mdx placebo mice. CRF2R-treated mice had decreased heart weights compared to placebo-treated mice. We conclude that CRF2R agonists should be further evaluated as a potential therapy for dystrophinopathies.
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Affiliation(s)
- Julie E Hall
- Department of Pediatrics, Rm. 2H18, McMaster University Medical Center, 1200 Main Street W., Hamilton, Ontario L8N 3Z5, Canada
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Duboc D, Meune C, Pierre B, Wahbi K, Eymard B, Toutain A, Berard C, Vaksmann G, Weber S, Bécane HM. Perindopril preventive treatment on mortality in Duchenne muscular dystrophy: 10 years' follow-up. Am Heart J 2007; 154:596-602. [PMID: 17719312 DOI: 10.1016/j.ahj.2007.05.014] [Citation(s) in RCA: 218] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Accepted: 05/14/2007] [Indexed: 12/16/2022]
Abstract
BACKGROUND Duchenne muscular dystrophy (DMD), an X-linked disorder due to lack of dystrophin, is associated with muscle weakness and myocardial dysfunction. Although preliminary data support the efficacy of angiotensin-converting enzyme inhibitors on left ventricular (LV) function, our aim was to examine the long-term impact of a preventive treatment with perindopril on mortality in children with DMD. METHODS Patients with DMD between the ages of 9.5 and 13 years presenting with normal LV ejection fraction were included in this prospective study. They were randomly assigned for 3 years to perindopril, 2 to 4 mg (group 1), or placebo (group 2) in a double-blind protocol, followed by open-label treatment with perindopril for up to 10 years. Survival rate at 10 years in each group is reported. RESULTS There were 28 patients assigned to group 1 and 29 to group 2. Baseline characteristics were similar in both groups. At the end of the 10 years' follow-up period, survival status was available for all included patients: 26 (92.9%) of 28 patients in group 1 were alive at 10 years versus 19 (65.5%) of 29 in group 2 (P = .02). Kaplan-Meier cumulative survival was significantly lower in group 2 than in group 1 (P = .013). CONCLUSION Early initiation of treatment with perindopril is associated with a lower mortality in patients with DMD with normal LV ejection fraction at study entry.
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Affiliation(s)
- Denis Duboc
- Department of Cardiology, Cochin Hospital, APHP, Paris V René Descartes University, Paris, France
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Duboc D, Meune C, Pierre B, Wahbi K, Eymard B, Toutain A, Berard C, Vaksmann G, Bécane HM. Perindopril preserves left ventricular function in X-linked Duchenne muscular dystrophy. Eur Heart J Suppl 2007. [DOI: 10.1093/eurheartj/sum036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Asai A, Sahani N, Kaneki M, Ouchi Y, Martyn JJ, Yasuhara SE. Primary role of functional ischemia, quantitative evidence for the two-hit mechanism, and phosphodiesterase-5 inhibitor therapy in mouse muscular dystrophy. PLoS One 2007; 2:e806. [PMID: 17726536 PMCID: PMC1950086 DOI: 10.1371/journal.pone.0000806] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Accepted: 07/25/2007] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Duchenne Muscular Dystrophy (DMD) is characterized by increased muscle damage and an abnormal blood flow after muscle contraction: the state of functional ischemia. Until now, however, the cause-effect relationship between the pathogenesis of DMD and functional ischemia was unclear. We examined (i) whether functional ischemia is necessary to cause contraction-induced myofiber damage and (ii) whether functional ischemia alone is sufficient to induce the damage. METHODOLOGY/PRINCIPAL FINDINGS In vivo microscopy was used to document assays developed to measure intramuscular red blood cell flux, to quantify the amount of vasodilatory molecules produced from myofibers, and to determine the extent of myofiber damage. Reversal of functional ischemia via pharmacological manipulation prevented contraction-induced myofiber damage in mdx mice, the murine equivalent of DMD. This result indicates that functional ischemia is required for, and thus an essential cause of, muscle damage in mdx mice. Next, to determine whether functional ischemia alone is enough to explain the disease, the extent of ischemia and the amount of myofiber damage were compared both in control and mdx mice. In control mice, functional ischemia alone was found insufficient to cause a similar degree of myofiber damage observed in mdx mice. Additional mechanisms are likely contributing to cause more severe myofiber damage in mdx mice, suggestive of the existence of a "two-hit" mechanism in the pathogenesis of this disease. CONCLUSIONS/SIGNIFICANCE Evidence was provided supporting the essential role of functional ischemia in contraction-induced myofiber damage in mdx mice. Furthermore, the first quantitative evidence for the "two-hit" mechanism in this disease was documented. Significantly, the vasoactive drug tadalafil, a phosphodiesterase 5 inhibitor, administered to mdx mice ameliorated muscle damage.
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Affiliation(s)
- Akihiro Asai
- Department of Anesthesiology and Critical Care, Shriners Hospital for Children, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Geriatric Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Nita Sahani
- Department of Anesthesiology and Critical Care, Shriners Hospital for Children, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Masao Kaneki
- Department of Anesthesiology and Critical Care, Shriners Hospital for Children, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yasuyoshi Ouchi
- Department of Geriatric Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - J.A. Jeevendra Martyn
- Department of Anesthesiology and Critical Care, Shriners Hospital for Children, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Shingo Egusa Yasuhara
- Department of Anesthesiology and Critical Care, Shriners Hospital for Children, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- * To whom correspondence should be addressed. E-mail:
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Kaczor JJ, Hall JE, Payne E, Tarnopolsky MA. Low intensity training decreases markers of oxidative stress in skeletal muscle of mdx mice. Free Radic Biol Med 2007; 43:145-54. [PMID: 17561103 DOI: 10.1016/j.freeradbiomed.2007.04.003] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2006] [Revised: 11/02/2006] [Accepted: 04/04/2007] [Indexed: 11/19/2022]
Abstract
Reactive oxygen species may contribute to the pathogenesis of muscular dystrophy. High intensity exercise clearly induces muscle damage in mdx mice; however, the effects of low intensity exercise training (LIT) on mdx muscle are less clear. We examined the effect of LIT on markers of oxidative stress (malondialdehyde and protein carbonyls), antioxidant (superoxide dismutase, catalase, and glutathione peroxidase), and mitochondrial (2-oxoglutarate dehydrogenase and cytochrome oxidase) enzymes in skeletal muscle of mdx and wild-type mice. Mdx and wild-type mice were allocated to LIT and sedentary groups. Malondialdehyde levels were higher in white muscle from sedentary mdx as compared to both sedentary and LIT wild-type mice (P<0.001). Protein carbonyl content was higher in white and red muscle of mdx versus wild-type mice (P<0.05). LIT was associated with lower levels of malondialdehyde and protein carbonyls in white muscle of mdx mice (decreased 38 and 44%, P<0.001 and P<0.01, respectively). Antioxidant and mitochondrial enzyme activities were higher in white muscle of mdx than in wild-type mice (P<0.05). LIT in mdx mice induced physiological adaptation resulting in lower levels of markers of oxidative stress that were not different than those from wild type. These results are of relevance for therapeutic exercise in patients with dystrophinopathy where exercise prescription remains controversial.
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Affiliation(s)
- Jan J Kaczor
- Department of Pediatrics, McMaster University Medical Center, 1200 Main St. W., Hamilton, Ontario, Canada L8N 3Z5.
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Heydemann A, Doherty KR, McNally EM. Genetic modifiers of muscular dystrophy: Implications for therapy. Biochim Biophys Acta Mol Basis Dis 2007; 1772:216-28. [PMID: 16916601 DOI: 10.1016/j.bbadis.2006.06.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Accepted: 06/22/2006] [Indexed: 10/24/2022]
Abstract
The genetic understanding of the muscular dystrophies has advanced considerably in the last two decades. Over 25 different individual genes are now known to produce muscular dystrophy, and many different "private" mutations have been described for each individual muscular dystrophy gene. For the more common forms of muscular dystrophy, phenotypic variability can be explained by precise mutations. However, for many genetic mutations, the presence of the identical mutation is associated with marked phenotypic range that affects muscle function as well as cardiac function. The explanation for phenotype variability in the muscular dystrophies is only now being explored. The availability of genetically engineered animal models has allowed the generation of single mutations on the background of highly inbred strain. Phenotypic variation that is altered by genetic background argues for the presence of genetic modifier loci that can ameliorate or enhance aspects of the dystrophic phenotype. A number of individual genes have been implicated as modifiers of muscular dystrophy by studies in genetically engineered mouse models of muscular dystrophy. The value of these genes and products is that the pathways identified through these experiments may be exploited for therapy.
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Affiliation(s)
- Ahlke Heydemann
- Department of Medicine, Section of Cardiology, The University of Chicago, Chicago, IL 60637, USA
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Anderson JE. The satellite cell as a companion in skeletal muscle plasticity: currency, conveyance, clue, connector and colander. ACTA ACUST UNITED AC 2006; 209:2276-92. [PMID: 16731804 DOI: 10.1242/jeb.02088] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Satellite cells are companions to voluntary muscle fibres, and are named for their intimate positional or ;satellite' relationship, as if revolving around fibres, like a satellite moon around the earth. Studies on the nature of at least some satellite cells, including their capabilities for self-renewal and for giving rise to multiple lineages in a stem cell-like function, are exploring the molecular basis of phenotypes described by markers of specialized function and gene expression in normal development, neuromuscular disease and aging. In adult skeletal muscle, the self-renewing capacity of satellite cells contributes to muscle growth, adaptation and regeneration. Muscle remodeling, such as demonstrated by changes in myofibre cross-sectional area and length, nerve and tendon junctions, and fibre-type distribution, occur in the absence of injury and provide broad functional and structural diversity among skeletal muscles. Those contributions to plasticity involve the satellite cell in at least five distinct roles, here described using metaphors for behaviour or the investigator's perspective. Satellite cells are the 'currency' of muscle; have a 'conveyance' role in adaptation by domains of cytoplasm along a myofibre; serve researchers, through a marker role, as 'clues' to various activities of muscle; are 'connectors' that physically, and through signalling and cell-fibre communications, bridge myofibres to the intra- and extra-muscular environment; and are equipped as metabolic and genetic filters or 'colanders' that can rectify or modulate particular signals. While all these roles are still under exploration, each contributes to the plasticity of skeletal muscle and thence to the overall biology and function of an organism. The use of metaphor for describing these roles helps to clarify and scrutinize the definitions that form the basis of our understanding of satellite cell biology: the metaphors provide the construct for various approaches to detect or test the nature of satellite cell functions in skeletal muscle plasticity.
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Affiliation(s)
- Judy E Anderson
- Department of Human Anatomy and Cell Science, Faculty of Medicine, University of Manitoba, Winnipeg, MB, R3E 0W3, Canada.
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Rooney JE, Welser JV, Dechert MA, Flintoff-Dye NL, Kaufman SJ, Burkin DJ. Severe muscular dystrophy in mice that lack dystrophin and alpha7 integrin. J Cell Sci 2006; 119:2185-95. [PMID: 16684813 DOI: 10.1242/jcs.02952] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The dystrophin glycoprotein complex links laminin in the extracellular matrix to the cell cytoskeleton. Loss of dystrophin causes Duchenne muscular dystrophy, the most common human X-chromosome-linked genetic disease. The alpha7beta1 integrin is a second transmembrane laminin receptor expressed in skeletal muscle. Mutations in the alpha7 integrin gene cause congenital myopathy in humans and mice. The alpha7beta1 integrin is increased in the skeletal muscle of Duchenne muscular dystrophy patients and mdx mice. This observation has led to the suggestion that dystrophin and alpha7beta1 integrin have complementary functional and structural roles. To test this hypothesis, we generated mice lacking both dystrophin and alpha7 integrin (mdx/alpha7(-/-)). The mdx/alpha7(-/-) mice developed early-onset muscular dystrophy and died at 2-4 weeks of age. Muscle fibers from mdx/alpha7(-/-) mice exhibited extensive loss of membrane integrity, increased centrally located nuclei and inflammatory cell infiltrate, greater necrosis and increased muscle degeneration compared to mdx or alpha7-integrin null animals. In addition, loss of dystrophin and/or alpha7 integrin resulted in altered expression of laminin-alpha2 chain. These results point to complementary roles for dystrophin and alpha7beta1 integrin in maintaining the functional integrity of skeletal muscle.
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MESH Headings
- Animals
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Dystrophin/deficiency
- Dystrophin/genetics
- Dystrophin/metabolism
- Integrin alpha Chains/deficiency
- Integrin alpha Chains/genetics
- Integrin alpha Chains/metabolism
- Laminin/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscle, Skeletal/ultrastructure
- Muscular Dystrophy, Duchenne/genetics
- Muscular Dystrophy, Duchenne/metabolism
- Muscular Dystrophy, Duchenne/pathology
- Regeneration
- Severity of Illness Index
- Survival Rate
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Judge LM, Haraguchiln M, Chamberlain JS. Dissecting the signaling and mechanical functions of the dystrophin-glycoprotein complex. J Cell Sci 2006; 119:1537-46. [PMID: 16569668 DOI: 10.1242/jcs.02857] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Duchenne muscular dystrophy is a severe disorder caused by mutations in the dystrophin gene. Dystrophin is required for assembly of the dystrophin-glycoprotein complex and provides a mechanically strong link between the cytoskeleton and the extracellular matrix. Several proteins in the complex also participate in signaling cascades, but the relationship between these signaling and mechanical functions in the development of muscular dystrophy is unclear. To explore the mechanisms of myofiber necrosis in dystrophin-deficient muscle, we tested the hypothesis that restoration of this complex without a link to the cytoskeleton ameliorates dystrophic pathology. Transgenic mice were generated that express Dp116, a non-muscle isoform of dystrophin that assembles the dystrophin-glycoprotein complex, in muscles of dystrophin-deficient mdx4cv mice. However, the phenotype of these mice was more severe than in controls. Displacement of utrophin by Dp116 correlated with the severity of dystrophy in different muscle groups. Comparison with other transgenic lines demonstrated that parts of the dystrophin central rod domain were required to localize neuronal nitric oxide synthase to the sarcolemma, but this was not correlated with presence or extent of dystrophy. Our results suggest that mechanical destabilization, rather than signaling dysfunction, is the primary cause of myofiber necrosis in dystrophin-deficient muscle.
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Affiliation(s)
- Luke M Judge
- University of Washington School of Medicine, Department of Neurology Box 357720, Seattle, WA 98195-7720, USA
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Barton ER, Morris L, Kawana M, Bish LT, Toursel T. Systemic administration of L-arginine benefits mdx skeletal muscle function. Muscle Nerve 2006; 32:751-60. [PMID: 16116642 DOI: 10.1002/mus.20425] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A major consequence of muscular dystrophy is that increased membrane fragility leads to high calcium influx and results in muscle degeneration and myonecrosis. Prior reports have demonstrated that increased nitric oxide production via L-arginine treatment of normal and mdx mice resulted in increased expression of utrophin and increased activation of muscle satellite cells, which could ameliorate the dystrophic pathology. We delivered L-arginine to normal and mdx mice, and examined muscles for any functional changes associated with its administration. Treated mdx muscles were less susceptible to contraction-induced damage and exhibited a rightward shift of the force-frequency relationship. Immunoblotting revealed increases in utrophin and gamma-sarcoglycan in the treated muscles. There was also a decrease in Evans blue dye uptake, indicating a reduction in myonecrosis. However, there was no decrease in serum creatine kinase or the proportion of central nuclei, nor any improvement in specific force. Together, these results show that L-arginine treatment can be beneficial to mdx muscle function, perhaps through a combination of enhanced calcium handling and increased utrophin, thereby decreasing muscle degeneration.
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Affiliation(s)
- Elisabeth R Barton
- Department of Anatomy and Cell Biology, School of Dental Medicine, 441 Levy Building, 240 South 40th Street, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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Archer JD, Vargas CC, Anderson JE. Persistent and improved functional gain in mdx dystrophic mice after treatment with L-arginine and deflazacort. FASEB J 2006; 20:738-40. [PMID: 16464957 DOI: 10.1096/fj.05-4821fje] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Although an increase in nitric oxide (NO) in muscle is reported to improve the outcome of deflazacort treatment for mdx mouse muscular dystrophy, the genetic homologue of Duchenne muscular dystrophy (DMD), the impact such treatment on the functional outcomes of the disease, including fiber susceptibility to exercise-induced injury, is not established. Experiments were designed to test whether treatment with deflazacort and L-arginine (a substrate for NO synthase, NOS) would change the extent of fiber injury induced by 24 h of voluntary exercise. The impact of exercise-related injury to induce a secondary regenerative response by muscle was also examined as corroborating evidence of muscle damage. Dystrophic mdx mice were treated for 3 wk with placebo, deflazacort, or deflazacort plus either L-arginine or N(G)-nitro-L-arginine methyl ester (a NOS inhibitor). Deflazacort, especially combined with L-arginine, spared quadriceps muscle from injury-induced regeneration (myf5 expression) compared with placebo treatment, despite an increase in membrane permeability immediately after exercise (assessed by Evans blue dye infiltration). Deflazacort alone prevented the typical progressive loss of function (measured as voluntary distance run over 24 h) that was observed 3 months later in placebo-treated mice. Therefore, combined deflazacort plus L-arginine treatment spared mdx dystrophic limb muscle from exercise-induced damage and the need for regeneration and induced a persistent functional improvement in distance run. Results suggest a potential new treatment option for improving the quality of life for boys with DMD.
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Affiliation(s)
- Jonathan D Archer
- Department of Human Anatomy and Cell Science, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
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Abstract
Duchenne muscular dystrophy (DMD) is a progressive, lethal, muscle wasting disease that affects 1 of 3500 boys born worldwide. The disease results from mutation of the dystrophin gene that encodes a cytoskeletal protein associated with the muscle cell membrane. Although gene therapy will likely provide the cure for DMD, it remains on the distant horizon, emphasizing the need for more rapid development of palliative treatments that build on improved understanding of the complex pathology of dystrophin deficiency. In this review, we have focused on therapeutic strategies that target downstream events in the pathologic progression of DMD. Much of this work has been developed initially using the dystrophin-deficient mdx mouse to explore basic features of the pathophysiology of dystrophin deficiency and to test potential therapeutic interventions to slow, reverse, or compensate for functional losses that occur in muscular dystrophy. In some cases, the initial findings in the mdx model have led to clinical treatments for DMD boys that have produced improvements in muscle function and quality of life. Many of these investigations have concerned interventions that can affect protein balance in muscle, by inhibiting specific proteases implicated in the DMD pathology, or by providing anabolic factors or depleting catabolic factors that can contribute to muscle wasting. Other investigations have exploited the use of anti-inflammatory agents that can reduce the contribution of leukocytes to promoting secondary damage to dystrophic muscle. A third general strategy is designed to increase the regenerative capacity of dystrophic muscle and thereby help retain functional muscle mass. Each of these general approaches to slowing the pathology of dystrophin deficiency has yielded encouragement and suggests that targeting downstream events in dystrophinopathy can yield worthwhile, functional improvements in DMD.
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Affiliation(s)
- James G Tidball
- Department of Physiological Science, University of California, Los Angeles, CA 90095, USA.
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