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Yang H, Wang H, Pan F, Guo Y, Cao L, Yan W, Gao Y. New Findings: Hindlimb Unloading Causes Nucleocytoplasmic Ca 2+ Overload and DNA Damage in Skeletal Muscle. Cells 2023; 12:cells12071077. [PMID: 37048150 PMCID: PMC10093444 DOI: 10.3390/cells12071077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 03/14/2023] [Accepted: 03/29/2023] [Indexed: 04/14/2023] Open
Abstract
Disuse atrophy of skeletal muscle is associated with a severe imbalance in cellular Ca2+ homeostasis and marked increase in nuclear apoptosis. Nuclear Ca2+ is involved in the regulation of cellular Ca2+ homeostasis. However, it remains unclear whether nuclear Ca2+ levels change under skeletal muscle disuse conditions, and whether changes in nuclear Ca2+ levels are associated with nuclear apoptosis. In this study, changes in Ca2+ levels, Ca2+ transporters, and regulatory factors in the nucleus of hindlimb unloaded rat soleus muscle were examined to investigate the effects of disuse on nuclear Ca2+ homeostasis and apoptosis. Results showed that, after hindlimb unloading, the nuclear envelope Ca2+ levels ([Ca2+]NE) and nucleocytoplasmic Ca2+ levels ([Ca2+]NC) increased by 78% (p < 0.01) and 106% (p < 0.01), respectively. The levels of Ca2+-ATPase type 2 (Ca2+-ATPase2), Ryanodine receptor 1 (RyR1), Inositol 1,4,5-tetrakisphosphate receptor 1 (IP3R1), Cyclic ADP ribose hydrolase (CD38) and Inositol 1,4,5-tetrakisphosphate (IP3) increased by 470% (p < 0.001), 94% (p < 0.05), 170% (p < 0.001), 640% (p < 0.001) and 12% (p < 0.05), respectively, and the levels of Na+/Ca2+ exchanger 3 (NCX3), Ca2+/calmodulin dependent protein kinase II (CaMK II) and Protein kinase A (PKA) decreased by 54% (p < 0.001), 33% (p < 0.05) and 5% (p > 0.05), respectively. In addition, DNase X is mainly localized in the myonucleus and its activity is elevated after hindlimb unloading. Overall, our results suggest that enhanced Ca2+ uptake from cytoplasm is involved in the increase in [Ca2+]NE after hindlimb unloading. Moreover, the increase in [Ca2+]NC is attributed to increased Ca2+ release into nucleocytoplasm and weakened Ca2+ uptake from nucleocytoplasm. DNase X is activated due to elevated [Ca2+]NC, leading to DNA fragmentation in myonucleus, ultimately initiating myonuclear apoptosis. Nucleocytoplasmic Ca2+ overload may contribute to the increased incidence of myonuclear apoptosis in disused skeletal muscle.
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Affiliation(s)
- Huajian Yang
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an 710069, China
- Key Laboratory of Resource Biology and Biotechnology in Western China, College of Life Sciences, Northwest University, Ministry of Education, Xi'an 710069, China
| | - Huiping Wang
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an 710069, China
- Key Laboratory of Resource Biology and Biotechnology in Western China, College of Life Sciences, Northwest University, Ministry of Education, Xi'an 710069, China
| | - Fangyang Pan
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an 710069, China
- Key Laboratory of Resource Biology and Biotechnology in Western China, College of Life Sciences, Northwest University, Ministry of Education, Xi'an 710069, China
| | - Yuxi Guo
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an 710069, China
- Key Laboratory of Resource Biology and Biotechnology in Western China, College of Life Sciences, Northwest University, Ministry of Education, Xi'an 710069, China
| | - Liqi Cao
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an 710069, China
- Key Laboratory of Resource Biology and Biotechnology in Western China, College of Life Sciences, Northwest University, Ministry of Education, Xi'an 710069, China
| | - Wenjing Yan
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an 710069, China
- Key Laboratory of Resource Biology and Biotechnology in Western China, College of Life Sciences, Northwest University, Ministry of Education, Xi'an 710069, China
| | - Yunfang Gao
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an 710069, China
- Key Laboratory of Resource Biology and Biotechnology in Western China, College of Life Sciences, Northwest University, Ministry of Education, Xi'an 710069, China
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2
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Mitochondrial Permeability Transition Causes Mitochondrial Reactive Oxygen Species- and Caspase 3-Dependent Atrophy of Single Adult Mouse Skeletal Muscle Fibers. Cells 2021; 10:cells10102586. [PMID: 34685566 PMCID: PMC8534155 DOI: 10.3390/cells10102586] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/16/2021] [Accepted: 09/25/2021] [Indexed: 02/03/2023] Open
Abstract
Elevated mitochondrial reactive oxygen species (mROS) and an increase in caspase-3 activity are established mechanisms that lead to skeletal muscle atrophy via the upregulation of protein degradation pathways. However, the mechanisms upstream of an increase in mROS and caspase-3 activity in conditions of muscle atrophy have not been identified. Based upon knowledge that an event known as mitochondrial permeability transition (MPT) causes an increase in mROS emission and the activation of caspase-3 via mitochondrial release of cytochrome c, as well as the circumstantial evidence for MPT in some muscle atrophy conditions, we tested MPT as a mechanism of atrophy. Briefly, treating cultured single mouse flexor digitorum brevis (FDB) fibers from adult mice with a chemical inducer of MPT (Bz423) for 24 h caused an increase in mROS and caspase-3 activity that was accompanied by a reduction in muscle fiber diameter that was able to be prevented by inhibitors of MPT, mROS, or caspase-3 (p < 0.05). Similarly, a four-day single fiber culture as a model of disuse caused atrophy that could be prevented by inhibitors of MPT, mROS, or activated caspase-3. As such, our results identify MPT as a novel mechanism of skeletal muscle atrophy that operates through mROS emission and caspase-3 activation.
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The effect of resistance training, detraining and retraining on muscle strength and power, myofibre size, satellite cells and myonuclei in older men. Exp Gerontol 2020; 133:110860. [DOI: 10.1016/j.exger.2020.110860] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 01/30/2020] [Accepted: 01/31/2020] [Indexed: 01/05/2023]
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Mázala DA, Novak JS, Hogarth MW, Nearing M, Adusumalli P, Tully CB, Habib NF, Gordish-Dressman H, Chen YW, Jaiswal JK, Partridge TA. TGF-β-driven muscle degeneration and failed regeneration underlie disease onset in a DMD mouse model. JCI Insight 2020; 5:135703. [PMID: 32213706 PMCID: PMC7213798 DOI: 10.1172/jci.insight.135703] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 02/26/2020] [Indexed: 01/23/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a chronic muscle disease characterized by poor myogenesis and replacement of muscle by extracellular matrix. Despite the shared genetic basis, severity of these deficits varies among patients. One source of these variations is the genetic modifier that leads to increased TGF-β activity. While anti-TGF-β therapies are being developed to target muscle fibrosis, their effect on the myogenic deficit is underexplored. Our analysis of in vivo myogenesis in mild (C57BL/10ScSn-mdx/J and C57BL/6J-mdxΔ52) and severe DBA/2J-mdx (D2-mdx) dystrophic models reveals no defects in developmental myogenesis in these mice. However, muscle damage at the onset of disease pathology, or by experimental injury, drives up TGF-β activity in the severe, but not in the mild, dystrophic models. Increased TGF-β activity is accompanied by increased accumulation of fibroadipogenic progenitors (FAPs) leading to fibro-calcification of muscle, together with failure of regenerative myogenesis. Inhibition of TGF-β signaling reduces muscle degeneration by blocking FAP accumulation without rescuing regenerative myogenesis. These findings provide in vivo evidence of early-stage deficit in regenerative myogenesis in D2-mdx mice and implicates TGF-β as a major component of a pathogenic positive feedback loop in this model, identifying this feedback loop as a therapeutic target.
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Affiliation(s)
- Davi A.G. Mázala
- Center for Genetic Medicine Research, Children’s Research Institute, Children’s National Hospital, Washington, DC, USA
| | - James S. Novak
- Center for Genetic Medicine Research, Children’s Research Institute, Children’s National Hospital, Washington, DC, USA
- Department of Genomics and Precision Medicine and
- Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Marshall W. Hogarth
- Center for Genetic Medicine Research, Children’s Research Institute, Children’s National Hospital, Washington, DC, USA
| | - Marie Nearing
- Center for Genetic Medicine Research, Children’s Research Institute, Children’s National Hospital, Washington, DC, USA
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Prabhat Adusumalli
- Center for Genetic Medicine Research, Children’s Research Institute, Children’s National Hospital, Washington, DC, USA
| | - Christopher B. Tully
- Center for Genetic Medicine Research, Children’s Research Institute, Children’s National Hospital, Washington, DC, USA
| | - Nayab F. Habib
- Center for Genetic Medicine Research, Children’s Research Institute, Children’s National Hospital, Washington, DC, USA
| | - Heather Gordish-Dressman
- Center for Genetic Medicine Research, Children’s Research Institute, Children’s National Hospital, Washington, DC, USA
- Department of Genomics and Precision Medicine and
- Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Yi-Wen Chen
- Center for Genetic Medicine Research, Children’s Research Institute, Children’s National Hospital, Washington, DC, USA
- Department of Genomics and Precision Medicine and
| | - Jyoti K. Jaiswal
- Center for Genetic Medicine Research, Children’s Research Institute, Children’s National Hospital, Washington, DC, USA
- Department of Genomics and Precision Medicine and
- Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Terence A. Partridge
- Center for Genetic Medicine Research, Children’s Research Institute, Children’s National Hospital, Washington, DC, USA
- Department of Genomics and Precision Medicine and
- Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
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Qaisar R, Karim A, Elmoselhi AB. Muscle unloading: A comparison between spaceflight and ground-based models. Acta Physiol (Oxf) 2020; 228:e13431. [PMID: 31840423 DOI: 10.1111/apha.13431] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Revised: 12/09/2019] [Accepted: 12/12/2019] [Indexed: 12/12/2022]
Abstract
Prolonged unloading of skeletal muscle, a common outcome of events such as spaceflight, bed rest and hindlimb unloading, can result in extensive metabolic, structural and functional changes in muscle fibres. With advancement in investigations of cellular and molecular mechanisms, understanding of disuse muscle atrophy has significantly increased. However, substantial gaps exist in our understanding of the processes dictating muscle plasticity during unloading, which prevent us from developing effective interventions to combat muscle loss. This review aims to update the status of knowledge and underlying mechanisms leading to cellular and molecular changes in skeletal muscle during unloading. We have also discussed advances in the understanding of contractile dysfunction during spaceflights and in ground-based models of muscle unloading. Additionally, we have elaborated on potential therapeutic interventions that show promising results in boosting muscle mass and strength during mechanical unloading. Finally, we have identified key gaps in our knowledge as well as possible research direction for the future.
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Affiliation(s)
- Rizwan Qaisar
- Department of Basic Medical Sciences College of Medicine University of Sharjah Sharjah UAE
| | - Asima Karim
- Department of Basic Medical Sciences College of Medicine University of Sharjah Sharjah UAE
| | - Adel B. Elmoselhi
- Department of Basic Medical Sciences College of Medicine University of Sharjah Sharjah UAE
- Department of Physiology Michigan State University East Lansing MI USA
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Schwartz LM. Skeletal Muscles Do Not Undergo Apoptosis During Either Atrophy or Programmed Cell Death-Revisiting the Myonuclear Domain Hypothesis. Front Physiol 2019; 9:1887. [PMID: 30740060 PMCID: PMC6356110 DOI: 10.3389/fphys.2018.01887] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 12/12/2018] [Indexed: 12/20/2022] Open
Abstract
Skeletal muscles are the largest cells in the body and are one of the few syncytial ones. There is a longstanding belief that a given nucleus controls a defined volume of cytoplasm, so when a muscle grows (hypertrophy) or shrinks (atrophy), the number of myonuclei change accordingly. This phenomenon is known as the “myonuclear domain hypothesis.” There is a general agreement that hypertrophy is accompanied by the addition of new nuclei from stem cells to help the muscles meet the enhanced synthetic demands of a larger cell. However, there is a considerable controversy regarding the fate of pre-existing nuclei during atrophy. Many researchers have reported that atrophy is accompanied by the dramatic loss of myonuclei via apoptosis. However, since there are many different non-muscle cell populations that reside within the tissue, these experiments cannot easily distinguish true myonuclei from those of neighboring mononuclear cells. Recently, two independent models, one from rodents and the other from insects, have demonstrated that nuclei are not lost from skeletal muscle fibers when they undergo either atrophy or programmed cell death. These and other data argue against the current interpretation of the myonuclear domain hypothesis and suggest that once a nucleus has been acquired by a muscle fiber it persists.
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Affiliation(s)
- Lawrence M Schwartz
- Department of Biology, Morrill Science Center, University of Massachusetts, Amherst, MA, United States
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Hernández-Ochoa EO, Banks Q, Schneider MF. Acute Elevated Glucose Promotes Abnormal Action Potential-Induced Ca 2+ Transients in Cultured Skeletal Muscle Fibers. J Diabetes Res 2017; 2017:1509048. [PMID: 28835899 PMCID: PMC5557004 DOI: 10.1155/2017/1509048] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 06/01/2017] [Accepted: 06/22/2017] [Indexed: 12/13/2022] Open
Abstract
A common comorbidity of diabetes is skeletal muscle dysfunction, which leads to compromised physical function. Previous studies of diabetes in skeletal muscle have shown alterations in excitation-contraction coupling (ECC)-the sequential link between action potentials (AP), intracellular Ca2+ release, and the contractile machinery. Yet, little is known about the impact of acute elevated glucose on the temporal properties of AP-induced Ca2+ transients and ionic underlying mechanisms that lead to muscle dysfunction. Here, we used high-speed confocal Ca2+ imaging to investigate the temporal properties of AP-induced Ca2+ transients, an intermediate step of ECC, using an acute in cellulo model of uncontrolled hyperglycemia (25 mM, 48 h.). Control and elevated glucose-exposed muscle fibers cultured for five days displayed four distinct patterns of AP-induced Ca2+ transients (phasic, biphasic, phasic-delayed, and phasic-slow decay); most control muscle fibers show phasic AP-induced Ca2+ transients, while most fibers exposed to elevated D-glucose displayed biphasic Ca2+ transients upon single field stimulation. We hypothesize that these changes in the temporal profile of the AP-induced Ca2+ transients are due to changes in the intrinsic excitable properties of the muscle fibers. We propose that these changes accompany early stages of diabetic myopathy.
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Affiliation(s)
- Erick O. Hernández-Ochoa
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- *Erick O. Hernández-Ochoa:
| | - Quinton Banks
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Martin F. Schneider
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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8
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Gundersen K. Muscle memory and a new cellular model for muscle atrophy and hypertrophy. ACTA ACUST UNITED AC 2016; 219:235-42. [PMID: 26792335 DOI: 10.1242/jeb.124495] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Memory is a process in which information is encoded, stored, and retrieved. For vertebrates, the modern view has been that it occurs only in the brain. This review describes a cellular memory in skeletal muscle in which hypertrophy is 'remembered' such that a fibre that has previously been large, but subsequently lost its mass, can regain mass faster than naive fibres. A new cell biological model based on the literature, with the most reliable methods for identifying myonuclei, can explain this phenomenon. According to this model, previously untrained fibres recruit myonuclei from activated satellite cells before hypertrophic growth. Even if subsequently subjected to grave atrophy, the higher number of myonuclei is retained, and the myonuclei seem to be protected against the elevated apoptotic activity observed in atrophying muscle tissue. Fibres that have acquired a higher number of myonuclei grow faster when subjected to overload exercise, thus the nuclei represent a functionally important 'memory' of previous strength. This memory might be very long lasting in humans, as myonuclei are stable for at least 15 years and might even be permanent. However, myonuclei are harder to recruit in the elderly, and if the long-lasting muscle memory also exists in humans, one should consider early strength training as a public health advice. In addition, myonuclei are recruited during steroid use and encode a muscle memory, at least in rodents. Thus, extending the exclusion time for doping offenders should be considered.
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Affiliation(s)
- Kristian Gundersen
- Department of Biosciences, University of Oslo, Blindernveien 31, Oslo N0316, Norway
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Coley WD, Bogdanik L, Vila MC, Yu Q, Van Der Meulen JH, Rayavarapu S, Novak JS, Nearing M, Quinn JL, Saunders A, Dolan C, Andrews W, Lammert C, Austin A, Partridge TA, Cox GA, Lutz C, Nagaraju K. Effect of genetic background on the dystrophic phenotype in mdx mice. Hum Mol Genet 2015; 25:130-45. [PMID: 26566673 DOI: 10.1093/hmg/ddv460] [Citation(s) in RCA: 141] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 11/05/2015] [Indexed: 12/13/2022] Open
Abstract
Genetic background significantly affects phenotype in multiple mouse models of human diseases, including muscular dystrophy. This phenotypic variability is partly attributed to genetic modifiers that regulate the disease process. Studies have demonstrated that introduction of the γ-sarcoglycan-null allele onto the DBA/2J background confers a more severe muscular dystrophy phenotype than the original strain, demonstrating the presence of genetic modifier loci in the DBA/2J background. To characterize the phenotype of dystrophin deficiency on the DBA/2J background, we created and phenotyped DBA/2J-congenic Dmdmdx mice (D2-mdx) and compared them with the original, C57BL/10ScSn-Dmdmdx (B10-mdx) model. These strains were compared with their respective control strains at multiple time points between 6 and 52 weeks of age. Skeletal and cardiac muscle function, inflammation, regeneration, histology and biochemistry were characterized. We found that D2-mdx mice showed significantly reduced skeletal muscle function as early as 7 weeks and reduced cardiac function by 28 weeks, suggesting that the disease phenotype is more severe than in B10-mdx mice. In addition, D2-mdx mice showed fewer central myonuclei and increased calcifications in the skeletal muscle, heart and diaphragm at 7 weeks, suggesting that their pathology is different from the B10-mdx mice. The new D2-mdx model with an earlier onset and more pronounced dystrophy phenotype may be useful for evaluating therapies that target cardiac and skeletal muscle function in dystrophin-deficient mice. Our data align the D2-mdx with Duchenne muscular dystrophy patients with the LTBP4 genetic modifier, making it one of the few instances of cross-species genetic modifiers of monogenic traits.
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Affiliation(s)
- William D Coley
- Research Center for Genetic Medicine, Children's National Health System, Washington, DC, USA
| | | | - Maria Candida Vila
- Research Center for Genetic Medicine, Children's National Health System, Washington, DC, USA, Department of Integrative Systems Biology, George Washington University School of Medicine, Washington, DC, USA
| | - Qing Yu
- Research Center for Genetic Medicine, Children's National Health System, Washington, DC, USA
| | - Jack H Van Der Meulen
- Research Center for Genetic Medicine, Children's National Health System, Washington, DC, USA
| | - Sree Rayavarapu
- Research Center for Genetic Medicine, Children's National Health System, Washington, DC, USA
| | - James S Novak
- Research Center for Genetic Medicine, Children's National Health System, Washington, DC, USA
| | - Marie Nearing
- Research Center for Genetic Medicine, Children's National Health System, Washington, DC, USA
| | - James L Quinn
- Research Center for Genetic Medicine, Children's National Health System, Washington, DC, USA
| | | | | | | | | | | | - Terence A Partridge
- Research Center for Genetic Medicine, Children's National Health System, Washington, DC, USA
| | | | | | - Kanneboyina Nagaraju
- Research Center for Genetic Medicine, Children's National Health System, Washington, DC, USA, Department of Integrative Systems Biology, George Washington University School of Medicine, Washington, DC, USA
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Duddy W, Duguez S, Johnston H, Cohen TV, Phadke A, Gordish-Dressman H, Nagaraju K, Gnocchi V, Low S, Partridge T. Muscular dystrophy in the mdx mouse is a severe myopathy compounded by hypotrophy, hypertrophy and hyperplasia. Skelet Muscle 2015; 5:16. [PMID: 25987977 PMCID: PMC4434871 DOI: 10.1186/s13395-015-0041-y] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 04/16/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Preclinical testing of potential therapies for Duchenne muscular dystrophy (DMD) is conducted predominantly of the mdx mouse. But lack of a detailed quantitative description of the pathology of this animal limits our ability to evaluate the effectiveness of putative therapies or their relevance to DMD. METHODS Accordingly, we have measured the main cellular components of muscle growth and regeneration over the period of postnatal growth and early pathology in mdx and wild-type (WT) mice; phalloidin binding is used as a measure of fibre size, myonuclear counts and BrdU labelling as records of myogenic activity. RESULTS We confirm a two-phase postnatal growth pattern in WT muscle: first, increase in myonuclear number over weeks 1 to 3, then expansion of myonuclear domain. Mdx muscle growth lags behind that of WT prior to overt signs of pathology. Fibres are smaller, with fewer myonuclei and smaller myonuclear domains. Moreover, satellite cells are more readily detached from mdx than WT muscle fibres. At 3 weeks, mdx muscles enter a phase of florid myonecrosis, accompanied by concurrent regeneration of an intensity that results in complete replacement of pre-existing muscle over the succeeding 3 to 4 weeks. Both WT and mdx muscles attain maximum size by 12 to 14 weeks, mdx muscle fibres being up to 50% larger than those of WT as they become increasingly branched. Mdx muscle fibres also become hypernucleated, containing twice as many myonuclei per sarcoplasmic volume, as those of WT, the excess corresponding to the number of centrally placed myonuclei. CONCLUSIONS The best-known consequence of lack of dystrophin that is common to DMD and the mdx mouse is the conspicuous necrosis and regeneration of muscle fibres. We present protocols for measuring this in terms both of loss of muscle nuclei previously labelled with BrdU and of the intensity of myonuclear labelling with BrdU administered during the regeneration period. Both measurements can be used to assess the efficacy of putative antinecrotic agents. We also show that lack of dystrophin is associated with a number of previously unsuspected abnormalities of muscle fibre structure and function that do not appear to be directly associated with myonecrosis.
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Affiliation(s)
- William Duddy
- Center for Genetic Medicine Research, Children's National Medical Center, 111 Michigan Avenue NW, Washington DC, 20010 USA ; Myology Center of Research, Institut de Myologie Pitié-Salpétrière - Bâtiment Babinski, 75651 Paris Cedex 13, France
| | - Stephanie Duguez
- Center for Genetic Medicine Research, Children's National Medical Center, 111 Michigan Avenue NW, Washington DC, 20010 USA ; Myology Center of Research, Institut de Myologie Pitié-Salpétrière - Bâtiment Babinski, 75651 Paris Cedex 13, France
| | - Helen Johnston
- Center for Genetic Medicine Research, Children's National Medical Center, 111 Michigan Avenue NW, Washington DC, 20010 USA
| | - Tatiana V Cohen
- Center for Genetic Medicine Research, Children's National Medical Center, 111 Michigan Avenue NW, Washington DC, 20010 USA ; Center for Genetic Muscle Disorders, Kennedy Krieger Institute, 801 N. Broadway, Baltimore, MD 21205 USA
| | - Aditi Phadke
- Center for Genetic Medicine Research, Children's National Medical Center, 111 Michigan Avenue NW, Washington DC, 20010 USA
| | - Heather Gordish-Dressman
- Center for Genetic Medicine Research, Children's National Medical Center, 111 Michigan Avenue NW, Washington DC, 20010 USA
| | - Kanneboyina Nagaraju
- Center for Genetic Medicine Research, Children's National Medical Center, 111 Michigan Avenue NW, Washington DC, 20010 USA
| | - Viola Gnocchi
- Center for Genetic Medicine Research, Children's National Medical Center, 111 Michigan Avenue NW, Washington DC, 20010 USA
| | - SiewHui Low
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218 USA
| | - Terence Partridge
- Center for Genetic Medicine Research, Children's National Medical Center, 111 Michigan Avenue NW, Washington DC, 20010 USA
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11
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Duguez S, Duddy W, Johnston H, Lainé J, Le Bihan MC, Brown KJ, Bigot A, Hathout Y, Butler-Browne G, Partridge T. Dystrophin deficiency leads to disturbance of LAMP1-vesicle-associated protein secretion. Cell Mol Life Sci 2013; 70:2159-74. [PMID: 23344255 PMCID: PMC11113779 DOI: 10.1007/s00018-012-1248-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 12/13/2012] [Accepted: 12/17/2012] [Indexed: 01/06/2023]
Abstract
Duchenne muscular dystrophy results from loss of the protein dystrophin, which links the intracellular cytoskeletal network with the extracellular matrix, but deficiency in this function does not fully explain the onset or progression of the disease. While some intracellular events involved in the degeneration of dystrophin-deficient muscle fibers have been well characterized, changes in their secretory profile are undescribed. To analyze the secretome profile of mdx myotubes independently of myonecrosis, we labeled the proteins of mdx and wild-type myotubes with stable isotope-labeled amino acids (SILAC), finding marked enrichment of vesicular markers in the mdx secretome. These included the lysosomal-associated membrane protein, LAMP1, that co-localized in vesicles with an over-secreted cytoskeletal protein, myosin light chain 1. These LAMP1/MLC1-3-positive vesicles accumulated in the cytosol of mdx myotubes and were secreted into the culture medium in a range of abnormal densities. Restitution of dystrophin expression, by exon skipping, to some 30 % of the control value, partially normalized the secretome profile and the excess LAMP1 accumulation. Together, our results suggest that a lack of dystrophin leads to a general dysregulation of vesicle trafficking. We hypothesize that disturbance of the export of proteins through vesicles occurs before, and then concurrently with, the myonecrotic cascade and contributes chronically to the pathophysiology of DMD, thereby presenting us with a range of new potential therapeutic targets.
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Affiliation(s)
- Stephanie Duguez
- Center for Genetic Medicine, Children’s Research Institute, Children’s National Medical Center, 111 Michigan Avenue, Washington, DC USA
- Institut de Myologie, UM76, Inserm U974, CNRS, UMR7215, Université Pierre et Marie Curie-Paris 6, Paris, 75013 France
| | - William Duddy
- Center for Genetic Medicine, Children’s Research Institute, Children’s National Medical Center, 111 Michigan Avenue, Washington, DC USA
- Institut de Myologie, UM76, Inserm U974, CNRS, UMR7215, Université Pierre et Marie Curie-Paris 6, Paris, 75013 France
| | - Helen Johnston
- Center for Genetic Medicine, Children’s Research Institute, Children’s National Medical Center, 111 Michigan Avenue, Washington, DC USA
| | - Jeanne Lainé
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- Département de Physiologie, Université Pierre Et Marie Curie-Paris 06, Site Pitié-Salpêtrière, Paris, 75013 France
| | - Marie Catherine Le Bihan
- Institut de Myologie, UM76, Inserm U974, CNRS, UMR7215, Université Pierre et Marie Curie-Paris 6, Paris, 75013 France
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Kristy J. Brown
- Center for Genetic Medicine, Children’s Research Institute, Children’s National Medical Center, 111 Michigan Avenue, Washington, DC USA
| | - Anne Bigot
- Institut de Myologie, UM76, Inserm U974, CNRS, UMR7215, Université Pierre et Marie Curie-Paris 6, Paris, 75013 France
| | - Yetrib Hathout
- Center for Genetic Medicine, Children’s Research Institute, Children’s National Medical Center, 111 Michigan Avenue, Washington, DC USA
| | - Gillian Butler-Browne
- Institut de Myologie, UM76, Inserm U974, CNRS, UMR7215, Université Pierre et Marie Curie-Paris 6, Paris, 75013 France
| | - Terence Partridge
- Center for Genetic Medicine, Children’s Research Institute, Children’s National Medical Center, 111 Michigan Avenue, Washington, DC USA
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Harafuji N, Schneiderat P, Walter MC, Chen YW. miR-411 is up-regulated in FSHD myoblasts and suppresses myogenic factors. Orphanet J Rare Dis 2013; 8:55. [PMID: 23561550 PMCID: PMC3637251 DOI: 10.1186/1750-1172-8-55] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/22/2013] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant muscle disorder, which is linked to the contraction of the D4Z4 array at chromosome 4q35. Recent studies suggest that this shortening of the D4Z4 array leads to aberrant expression of double homeobox protein 4 (DUX4) and causes FSHD. In addition, misregulation of microRNAs (miRNAs) has been reported in muscular dystrophies including FSHD. In this study, we identified a miRNA that is differentially expressed in FSHD myoblasts and investigated its function. METHODS To identify misregulated miRNAs and their potential targets in FSHD myoblasts, we performed expression profiling of both miRNA and mRNA using TaqMan Human MicroRNA Arrays and Affymetrix Human Genome U133A plus 2.0 microarrays, respectively. In addition, we over-expressed miR-411 in C₂C₁₂ cells to determine the effect of miR-411 on myogenic markers. RESULTS Using miRNA and mRNA expression profiling, we identified 8 miRNAs and 1,502 transcripts that were differentially expressed in FSHD myoblasts during cell proliferation. One of the 8 differentially expressed miRNAs, miR-411, was validated by quantitative RT-PCR in both primary (2.1 fold, p<0.01) and immortalized (2.7 fold, p<0.01) myoblasts. In situ hybridization showed cytoplasmic localization of miR-411 in FSHD myoblasts. By analyzing both miRNA and mRNA data using Partek Genomics Suite, we identified 4 mRNAs potentially regulated by miR-411 including YY1 associated factor 2 (YAF2). The down-regulation of YAF2 in immortalized myoblasts was validated by immunoblotting (-3.7 fold, p<0.01). C₂C₁₂ cells were transfected with miR-411 to determine whether miR-411 affects YAF2 expression in myoblasts. The results showed that over-expression of miR-411 reduced YAF2 mRNA expression. In addition, expression of myogenic markers including Myod, myogenin, and myosin heavy chain 1 (Myh1) were suppressed by miR-411. CONCLUSIONS The study demonstrated that miR-411 was differentially expressed in FSHD myoblasts and may play a role in regulating myogenesis.
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Affiliation(s)
- Naoe Harafuji
- Center for Genetic Medicine Research, Children’s Research Institute, Washington, DC, USA
| | - Peter Schneiderat
- Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians-University of Munich, Munich, Germany
| | - Maggie C Walter
- Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians-University of Munich, Munich, Germany
| | - Yi-Wen Chen
- Center for Genetic Medicine Research, Children’s Research Institute, Washington, DC, USA
- Department of Integrative Systems Biology and Department of Pediatrics, George Washington University, Washington, DC, USA
- Center for Genetic Medicine Research, Children’s National Medical Center, 111 Michigan Avenue, NW, Washington, DC 20010, USA
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Bruusgaard JC, Egner IM, Larsen TK, Dupre-Aucouturier S, Desplanches D, Gundersen K. No change in myonuclear number during muscle unloading and reloading. J Appl Physiol (1985) 2012; 113:290-6. [PMID: 22582213 DOI: 10.1152/japplphysiol.00436.2012] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Muscle fibers are the cells in the body with the largest volume, and they have multiple nuclei serving different domains of cytoplasm. A large body of previous literature has suggested that atrophy induced by hindlimb suspension leads to a loss of "excessive" myonuclei by apoptosis. We demonstrate here that atrophy induced by hindlimb suspension does not lead to loss of myonuclei despite a strong increase in apoptotic activity of other types of nuclei within the muscle tissue. Thus hindlimb suspension turns out to be similar to other atrophy models such as denervation, nerve impulse block, and antagonist ablation. We discuss how the different outcome of various studies can be attributed to difficulties in separating myonuclei from other nuclei, and to systematic differences in passive properties between normal and unloaded muscles. During reload, after hindlimb suspension, a radial regrowth is observed, which has been believed to be accompanied by recruitment of new myonuclei from satellite cells. The lack of nuclear loss during unloading, however, puts these findings into question. We observed that reload led to an increase in cross sectional area of 59%, and fiber size was completely restored to the presuspension levels. Despite this notable growth there was no increase in the number of myonuclei. Thus radial regrowth seems to differ from de novo hypertrophy in that nuclei are only added during the latter. We speculate that the number of myonuclei might reflect the largest size the muscle fibers have had in its previous history.
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Affiliation(s)
- J C Bruusgaard
- Department of Molecular Biosciences, University of Oslo, Oslo, Norway
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