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Ueta R, Tezuka T, Izawa Y, Miyoshi S, Nagatoishi S, Tsumoto K, Yamanashi Y. The carboxyl-terminal region of Dok-7 plays a key, but not essential, role in activation of muscle-specific receptor kinase MuSK and neuromuscular synapse formation. J Biochem 2017; 161:269-277. [PMID: 28069867 DOI: 10.1093/jb/mvw073] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Accepted: 09/21/2016] [Indexed: 11/14/2022] Open
Abstract
As the synapse between a motor neuron and skeletal muscle, the neuromuscular junction (NMJ) is required for muscle contraction. The formation and maintenance of NMJs are controlled by the muscle-specific receptor kinase MuSK. Dok-7 is the essential cytoplasmic activator of MuSK, and indeed mice lacking Dok-7 form no NMJs. Moreover, DOK7 gene mutations underlie DOK7 myasthenia, an NMJ synaptopathy. Previously, we failed to detect MuSK activation in myotubes by Dok-7 mutated in the N-terminal pleckstrin homology (PH) or phosphotyrosine binding (PTB) domain or that lacked the C-terminal region (Dok-7-ΔC). Here, we found by quantitative analysis that Dok-7-ΔC marginally, but significantly, activated MuSK in myotubes, unlike the PH- or PTB-mutant. Purified, recombinant Dok-7-ΔC, but not other mutants, also showed marginal ability to activate MuSK's cytoplasmic portion, carrying the kinase domain. Consistently, forced expression of Dok-7-ΔC rescued Dok-7-deficient mice from neonatal lethality caused by the lack of NMJs, indicating restored MuSK activation and NMJ formation. However, these mice showed only marginal activation of MuSK and died by 3 weeks of age apparently due to an abnormally small number and size of NMJs. Thus, Dok-7's C-terminal region plays a key, but not fully essential, role in MuSK activation and NMJ formation.
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Affiliation(s)
- Ryo Ueta
- Division of Genetics, Department of Cancer Biology
| | - Tohru Tezuka
- Division of Genetics, Department of Cancer Biology
| | - Yosuke Izawa
- Division of Genetics, Department of Cancer Biology
| | | | - Satoru Nagatoishi
- Department of Bioengineering, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan.,Drug Discovery Initiative, The University of Tokyo, Tokyo 113-0033, Japan
| | - Kouhei Tsumoto
- Department of Bioengineering, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan.,Drug Discovery Initiative, The University of Tokyo, Tokyo 113-0033, Japan.,Laboratory of Medical Proteomics, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
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Abstract
Myasthenia gravis is an autoimmune disease of the neuromuscular junction (NMJ) caused by antibodies that attack components of the postsynaptic membrane, impair neuromuscular transmission, and lead to weakness and fatigue of skeletal muscle. This can be generalised or localised to certain muscle groups, and involvement of the bulbar and respiratory muscles can be life threatening. The pathogenesis of myasthenia gravis depends upon the target and isotype of the autoantibodies. Most cases are caused by immunoglobulin (Ig)G1 and IgG3 antibodies to the acetylcholine receptor (AChR). They produce complement-mediated damage and increase the rate of AChR turnover, both mechanisms causing loss of AChR from the postsynaptic membrane. The thymus gland is involved in many patients, and there are experimental and genetic approaches to understand the failure of immune tolerance to the AChR. In a proportion of those patients without AChR antibodies, antibodies to muscle-specific kinase (MuSK), or related proteins such as agrin and low-density lipoprotein receptor-related protein 4 (LRP4), are present. MuSK antibodies are predominantly IgG4 and cause disassembly of the neuromuscular junction by disrupting the physiological function of MuSK in synapse maintenance and adaptation. Here we discuss how knowledge of neuromuscular junction structure and function has fed into understanding the mechanisms of AChR and MuSK antibodies. Myasthenia gravis remains a paradigm for autoantibody-mediated conditions and these observations show how much there is still to learn about synaptic function and pathological mechanisms.
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Affiliation(s)
- William D Phillips
- Physiology and Bosch Institute, University of Sydney, Anderson Stuart Bldg (F13), Sydney, 2006, Australia
| | - Angela Vincent
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
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Abstract
PURPOSE OF REVIEW Denervation is a hallmark of age-related and other types of muscle wasting. This review focuses on recent insights and current viewpoints regarding the mechanisms and clinical relevance of maintaining the neuromuscular junction to counteract muscle wasting resulting from aging or neural disease/damage. RECENT FINDINGS Activity-dependent regulation of autophagy, the agrin-muscle specific kinase-Lrp4 signaling axis, and sympathetic modulation are principal mechanisms involved in stabilizing the neuromuscular junction. These findings are derived from several animal models and were largely confirmed by human gene expression analysis as well as insights from rare neuromuscular diseases such as amyotrophic lateral sclerosis and congenital myasthenic syndromes. Based on these insights, agrin-derived fragments are currently being evaluated as biomarkers for age-related muscle wasting. Tuning of autophagy, of the agrin pathway, and of sympathetic input are being studied as clinical treatment of muscle wasting disorders. SUMMARY Basic research has revealed that maintenance of neuromuscular junctions and a few signaling pathways are important in the context of age-dependent and other forms of muscle wasting. These findings have recently started to enter clinical practice, but further research needs to substantiate and refine our knowledge.
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Affiliation(s)
- Rüdiger Rudolf
- Interdisciplinary Center for Neuroscience, University of Heidelberg, Germany
- Institute of Molecular and Cell Biology, Mannheim University of Applied Science, Germany
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Germany
| | - Michael R. Deschenes
- Department of Kinesiology and Health Sciences, The College of William and Mary, Williamsburg, VA, USA
| | - Marco Sandri
- Department of Biomedical Science, University of Padua, Italy
- Venetian Institute of Molecular Medicine (VIMM), Padua, Italy
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Eguchi T, Tezuka T, Miyoshi S, Yamanashi Y. Postnatal knockdown of dok-7 gene expression in mice causes structural defects in neuromuscular synapses and myasthenic pathology. Genes Cells 2016; 21:670-6. [PMID: 27091576 DOI: 10.1111/gtc.12370] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 03/08/2016] [Indexed: 02/01/2023]
Abstract
The neuromuscular junction (NMJ) is a synapse between a motor neuron and skeletal muscle and is required for muscle contraction. The formation and maintenance of NMJs are governed by the muscle-specific receptor tyrosine kinase MuSK. We previously showed that the muscle cytoplasmic protein Dok-7 is an essential activator of MuSK. Indeed, mice lacking either Dok-7 or MuSK form no NMJs, and defects in the human DOK7 gene underlie a congenital myasthenic syndrome (an NMJ disorder). However, it remains unproven whether Dok-7 is required for the postnatal maintenance of NMJs. In this study, we generated recombinant adeno-associated virus (AAV) vectors encoding short hairpin RNAs targeting the mouse dok-7 gene (AAV-shD7). Systemic administration of AAV-shD7 into 2-week-old mice down-regulated dok-7 expression in muscle and induced myasthenic symptoms including reduction in body weight and motor function. Moreover, AAV-shD7 treatment suppressed MuSK-dependent gene expression of NMJ components and reduced the size of NMJs. These results demonstrate that correct, physiological levels of dok-7 expression are required for the postnatal maintenance of NMJs.
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Affiliation(s)
- Takahiro Eguchi
- Division of Genetics, Department of Cancer Biology, The Institute of Medical Science, The University of Tokyo, Tokyo, 108-8639, Japan
| | - Tohru Tezuka
- Division of Genetics, Department of Cancer Biology, The Institute of Medical Science, The University of Tokyo, Tokyo, 108-8639, Japan
| | - Sadanori Miyoshi
- Division of Genetics, Department of Cancer Biology, The Institute of Medical Science, The University of Tokyo, Tokyo, 108-8639, Japan
| | - Yuji Yamanashi
- Division of Genetics, Department of Cancer Biology, The Institute of Medical Science, The University of Tokyo, Tokyo, 108-8639, Japan
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Wang L, Wang Z, Zhang F, Zhu R, Bi J, Wu J, Zhang H, Wu H, Kong W, Yu B, Yu X. Enhancing Transgene Expression from Recombinant AAV8 Vectors in Different Tissues Using Woodchuck Hepatitis Virus Post-Transcriptional Regulatory Element. Int J Med Sci 2016; 13:286-91. [PMID: 27076785 PMCID: PMC4829541 DOI: 10.7150/ijms.14152] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2015] [Accepted: 02/04/2016] [Indexed: 12/13/2022] Open
Abstract
Adeno-associated virus (AAV) vectors have been utilized extensively in gene therapy and gene function studies, as strong transgene expression is a prerequisite for positive outcomes. AAV8 was reported as the most efficient AAV serotype for transduction of the liver, brain and muscle compared with other serotypes. However, AAV8-mediated transduction of human hepatocytes is rather poor with approximately 20-fold lower efficiency compared with that of mouse hepatocytes. Therefore, we applied the woodchuck hepatitis virus post-transcriptional regulatory element (WPRE) to enhance AAV8-mediated transgene expression driven by a combination promoter (CAG promoter) with a CMV-IE enhancer and chicken beta-actin promoter for a more efficient viral vector. Transgene expression from recombinant AAV8 (rAAV8) vectors harboring a red fluorescent protein (RFP) reporter gene with or without WPRE were evaluated in vitro and in vivo. The results demonstrated that WPRE improved AAV8-mediated RFP expression in different cell lines with clear increases of transgene expression in the liver, brain or muscle of animals. The findings of this study will help to substantially reduce the quantity of viral particles that must be injected in order to reach a therapeutic level of transgene expression in gene therapy. Consequently, such dose reductions may lessen the potential risks associated with high doses of viral vectors.
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Affiliation(s)
- Lizheng Wang
- 1. National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China
| | - Zixuan Wang
- 1. National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China
| | - Fangfang Zhang
- 1. National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China
| | - Rui Zhu
- 1. National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China
| | - Jinpeng Bi
- 1. National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China
| | - Jiaxin Wu
- 1. National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China
| | - Haihong Zhang
- 1. National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China
| | - Hui Wu
- 1. National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China
| | - Wei Kong
- 1. National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China
- 2. Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, School of Life Sciences, Jilin University, Changchun 130012, China
| | - Bin Yu
- 1. National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China
| | - Xianghui Yu
- 1. National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China
- 2. Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, School of Life Sciences, Jilin University, Changchun 130012, China
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Yin XF, Xu HM, Jiang YX, Zhi YL, Liu YX, Xiang HW, Liu K, Ding XD, Sun P. Lentivirus-mediated Persephin over-expression in Parkinson's disease rats. Neural Regen Res 2016; 10:1814-8. [PMID: 26807117 PMCID: PMC4705794 DOI: 10.4103/1673-5374.170309] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Persephin, together with glial cell line-derived neurotrophic factor and neurturin, has a neurotrophic effect and promotes the survival of motor neurons cultured in vitro. In this study, dopaminergic neurons in the substantia nigra of rats were transfected with the Persephin gene. One week later 6-hydroxydopamine was injected into the anterior medial bundle to establish a Parkinson's disease model in the rats. Results found that the number of dopaminergic neurons in the substantia nigra increased, tyrosine hydroxylase expression was upregulated and concentrations of dopamine and its metabolites in corpus striatum were increased after pretreatment with Persephin gene. In addition, the rotating effect of the induced Parkinson's disease rats was much less in the group pretreated with the Persephin gene. Persephin has a neuroprotective effect on the 6-hydroxydopamine-induced Parkinson's disease through protecting dopaminergic neurons.
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Affiliation(s)
- Xiao-Feng Yin
- Department of Neurosurgery, the Second Affiliated Hospital of Shanxi Medical University, Taiyuan, Shanxi Province, China
| | - Hua-Min Xu
- Department of Physiology, Qingdao University, Qingdao, Shandong Province, China
| | - Yun-Xia Jiang
- Nursing College of Qingdao University, Qingdao, Shandong Province, China
| | - Yun-Lai Zhi
- Department of Pediatric Surgery, Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China
| | - Yu-Xiu Liu
- Department of Nursing, Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China
| | - Heng-Wei Xiang
- Department of Neurosurgery, Affiliated Hospital of Medical College, Qingdao University, Qingdao, Shandong Province, China
| | - Kai Liu
- Department of Neurosurgery, Affiliated Hospital of Medical College, Qingdao University, Qingdao, Shandong Province, China
| | - Xiao-Dong Ding
- Department of Neurosurgery, Affiliated Hospital of Medical College, Qingdao University, Qingdao, Shandong Province, China
| | - Peng Sun
- Department of Neurosurgery, Affiliated Hospital of Medical College, Qingdao University, Qingdao, Shandong Province, China
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MINEGISHI Y, OTA N, SOGA S, SHIMOTOYODOME A. Effects of Nutritional Supplementation with Milk Fat Globule Membrane on Physical and Muscle Function in Healthy Adults Aged 60 and Over with Semiweekly Light Exercise: A Randomized Double-Blind, Placebo-Controlled Pilot Trial. J Nutr Sci Vitaminol (Tokyo) 2016; 62:409-415. [DOI: 10.3177/jnsv.62.409] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
| | | | - Satoko SOGA
- Biological Science Research, Kao Corporation
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58
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Ghazanfari N, Linsao ELTB, Trajanovska S, Morsch M, Gregorevic P, Liang SX, Reddel SW, Phillips WD. Forced expression of muscle specific kinase slows postsynaptic acetylcholine receptor loss in a mouse model of MuSK myasthenia gravis. Physiol Rep 2015; 3:3/12/e12658. [PMID: 26702075 PMCID: PMC4760443 DOI: 10.14814/phy2.12658] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 11/20/2015] [Indexed: 12/12/2022] Open
Abstract
We investigated the influence of postsynaptic tyrosine kinase signaling in a mouse model of muscle‐specific kinase (MuSK) myasthenia gravis (MG). Mice administered repeated daily injections of IgG from MuSK MG patients developed impaired neuromuscular transmission due to progressive loss of acetylcholine receptor (AChR) from the postsynaptic membrane of the neuromuscular junction. In this model, anti‐MuSK‐positive IgG caused a reduction in motor endplate immunolabeling for phosphorylated Src‐Y418 and AChR β‐subunit‐Y390 before any detectable loss of MuSK or AChR from the endplate. Adeno‐associated viral vector (rAAV) encoding MuSK fused to enhanced green fluorescent protein (MuSK‐EGFP) was injected into the tibialis anterior muscle to increase MuSK synthesis. When mice were subsequently challenged with 11 daily injections of IgG from MuSK MG patients, endplates expressing MuSK‐EGFP retained more MuSK and AChR than endplates of contralateral muscles administered empty vector. Recordings of compound muscle action potentials from myasthenic mice revealed less impairment of neuromuscular transmission in muscles that had been injected with rAAV‐MuSK‐EGFP than contralateral muscles (empty rAAV controls). In contrast to the effects of MuSK‐EGFP, forced expression of rapsyn‐EGFP provided no such protection to endplate AChR when mice were subsequently challenged with MuSK MG IgG. In summary, the immediate in vivo effect of MuSK autoantibodies was to suppress MuSK‐dependent tyrosine phosphorylation of proteins in the postsynaptic membrane, while increased MuSK synthesis protected endplates against AChR loss. These results support the hypothesis that reduced MuSK kinase signaling initiates the progressive disassembly of the postsynaptic membrane scaffold in this mouse model of MuSK MG.
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Affiliation(s)
- Nazanin Ghazanfari
- Physiology and Bosch Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Erna L T B Linsao
- Physiology and Bosch Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Sofie Trajanovska
- Physiology and Bosch Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Marco Morsch
- Physiology and Bosch Institute, University of Sydney, Sydney, New South Wales, Australia Department of Biomedical Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Paul Gregorevic
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Simon X Liang
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Liaoning Medical University, Liaoning, China
| | - Stephen W Reddel
- Department of Molecular Medicine, Concord Hospital, Sydney, New South Wales, Australia
| | - William D Phillips
- Physiology and Bosch Institute, University of Sydney, Sydney, New South Wales, Australia
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Sorbs1 and -2 Interact with CrkL and Are Required for Acetylcholine Receptor Cluster Formation. Mol Cell Biol 2015; 36:262-70. [PMID: 26527617 PMCID: PMC4719301 DOI: 10.1128/mcb.00775-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 10/23/2015] [Indexed: 01/30/2023] Open
Abstract
Crk and CrkL are noncatalytic adaptor proteins necessary for the formation of neuromuscular synapses which function downstream of muscle-specific kinase (MuSK), a receptor tyrosine kinase expressed in skeletal muscle, and the MuSK binding protein Dok-7. How Crk/CrkL regulate neuromuscular endplate formation is not known. To better understand the roles of Crk/CrkL, we identified CrkL binding proteins using mass spectrometry and have identified Sorbs1 and Sorbs2 as two functionally redundant proteins that associate with the initiating MuSK/Dok-7/Crk/CrkL complex, regulate acetylcholine receptor (AChR) clustering in vitro, and are localized at synapses in vivo.
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60
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Soga S, Ota N, Shimotoyodome A. Dietary milk fat globule membrane supplementation combined with regular exercise improves skeletal muscle strength in healthy adults: a randomized double-blind, placebo-controlled, crossover trial. Nutr J 2015; 14:85. [PMID: 26303780 PMCID: PMC4547417 DOI: 10.1186/s12937-015-0073-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 08/12/2015] [Indexed: 01/20/2023] Open
Abstract
Background Our previous studies demonstrated that dietary supplementation with milk fat globule membrane (MFGM) combined with habitual exercise improved muscle strength by stimulating neuromuscular development in mice. This study aimed to demonstrate the beneficial effects of dietary MFGM supplementation plus regular exercise on muscle strength and neuromuscular function in healthy humans. Methods The study was designed as a randomized, double-blind, placebo-controlled, crossover trial. Fourteen Japanese adults aged 31–48 years took daily MFGM (1 g) or placebo tablets during the 4-week study period and attended a training program twice a week. Physical function tests and surface electromyography (EMG) were conducted at baseline and at the end of the study period. Results The MFGM group had significantly greater leg extension strength than the placebo group after the 4-week study period. Surface EMG showed that the MFGM group had a significantly higher root mean square amplitude than the placebo group, which indicated that the MFGM group had higher motor unit activity. Conclusions Dietary MFGM supplementation combined with regular exercise improves skeletal muscle strength, which may be due to increased motor unit recruitment in healthy Japanese middle-aged adults.
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Affiliation(s)
- Satoko Soga
- Biological Science Laboratories, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga-gun, Tochigi, 321-3497, Japan.
| | - Noriyasu Ota
- Biological Science Laboratories, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga-gun, Tochigi, 321-3497, Japan.
| | - Akira Shimotoyodome
- Biological Science Laboratories, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga-gun, Tochigi, 321-3497, Japan.
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Nichols B, Takeda S, Yokota T. Nonmechanical Roles of Dystrophin and Associated Proteins in Exercise, Neuromuscular Junctions, and Brains. Brain Sci 2015; 5:275-98. [PMID: 26230713 PMCID: PMC4588140 DOI: 10.3390/brainsci5030275] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/29/2015] [Accepted: 07/21/2015] [Indexed: 02/06/2023] Open
Abstract
Dystrophin-glycoprotein complex (DGC) is an important structural unit in skeletal muscle that connects the cytoskeleton (f-actin) of a muscle fiber to the extracellular matrix (ECM). Several muscular dystrophies, such as Duchenne muscular dystrophy, Becker muscular dystrophy, congenital muscular dystrophies (dystroglycanopathies), and limb-girdle muscular dystrophies (sarcoglycanopathies), are caused by mutations in the different DGC components. Although many early studies indicated DGC plays a crucial mechanical role in maintaining the structural integrity of skeletal muscle, recent studies identified novel roles of DGC. Beyond a mechanical role, these DGC members play important signaling roles and act as a scaffold for various signaling pathways. For example, neuronal nitric oxide synthase (nNOS), which is localized at the muscle membrane by DGC members (dystrophin and syntrophins), plays an important role in the regulation of the blood flow during exercise. DGC also plays important roles at the neuromuscular junction (NMJ) and in the brain. In this review, we will focus on recently identified roles of DGC particularly in exercise and the brain.
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Affiliation(s)
- Bailey Nichols
- Department of Medical Genetics, University of Alberta Faculty of Medicine and Dentistry.
| | - Shin'ichi Takeda
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1, Ogawa-higashi, Kodaira, Tokyo 187-8502, Japan.
| | - Toshifumi Yokota
- Department of Medical Genetics, University of Alberta Faculty of Medicine and Dentistry.
- Muscular Dystrophy Canada Research Chair, 8812-112 St, Edmonton, AB T6G 2H7, Canada.
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Tintignac LA, Brenner HR, Rüegg MA. Mechanisms Regulating Neuromuscular Junction Development and Function and Causes of Muscle Wasting. Physiol Rev 2015; 95:809-52. [DOI: 10.1152/physrev.00033.2014] [Citation(s) in RCA: 224] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The neuromuscular junction is the chemical synapse between motor neurons and skeletal muscle fibers. It is designed to reliably convert the action potential from the presynaptic motor neuron into the contraction of the postsynaptic muscle fiber. Diseases that affect the neuromuscular junction may cause failure of this conversion and result in loss of ambulation and respiration. The loss of motor input also causes muscle wasting as muscle mass is constantly adapted to contractile needs by the balancing of protein synthesis and protein degradation. Finally, neuromuscular activity and muscle mass have a major impact on metabolic properties of the organisms. This review discusses the mechanisms involved in the development and maintenance of the neuromuscular junction, the consequences of and the mechanisms involved in its dysfunction, and its role in maintaining muscle mass during aging. As life expectancy is increasing, loss of muscle mass during aging, called sarcopenia, has emerged as a field of high medical need. Interestingly, aging is also accompanied by structural changes at the neuromuscular junction, suggesting that the mechanisms involved in neuromuscular junction maintenance might be disturbed during aging. In addition, there is now evidence that behavioral paradigms and signaling pathways that are involved in longevity also affect neuromuscular junction stability and sarcopenia.
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Affiliation(s)
- Lionel A. Tintignac
- Biozentrum, University of Basel, Basel, Switzerland; Department of Biomedicine, University of Basel, Basel, Switzerland; and INRA, UMR866 Dynamique Musculaire et Métabolisme, Montpellier, France
| | - Hans-Rudolf Brenner
- Biozentrum, University of Basel, Basel, Switzerland; Department of Biomedicine, University of Basel, Basel, Switzerland; and INRA, UMR866 Dynamique Musculaire et Métabolisme, Montpellier, France
| | - Markus A. Rüegg
- Biozentrum, University of Basel, Basel, Switzerland; Department of Biomedicine, University of Basel, Basel, Switzerland; and INRA, UMR866 Dynamique Musculaire et Métabolisme, Montpellier, France
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Abstract
INTRODUCTION An estimated 25 million Americans are living with rare diseases. Adeno-associated virus (AAV)-mediated gene therapy is an emerging therapeutic option for the more than 7,000 identified rare diseases. This paper highlights the benefits of AAV therapy compared to conventional small molecules, discusses current pre-clinical and clinical applications of AAV-mediated gene therapy, and offers insights into cutting edge research that will shape the future of AAV for broad therapeutic use. AREAS COVERED In this review the biology of AAV and our ability to generate disease-specific variants is summarized. Limitations of current therapy are reviewed, with an emphasis on immune detection of virus, viral tropism and tissue targeting, and limitations of gene expression. Information for this review was found using PubMed and clinicaltrials.gov. EXPERT OPINION Currently the scope of clinical trials of AAV gene therapy is concentrated in an array of phase I/II safety trials with less than two dozen rare diseases featured. Pre-clinical, translational studies are expanding in number as developments within the last decade have made generation of improved AAV vectors available to more researchers. Further, one bottleneck that is being overcome is the availability of disease models, which will allow for improved preclinical testing and advancement of AAV to more clinical applications.
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Affiliation(s)
- Eric Hastie
- Gene Therapy Center, University of North Carolina, Chapel Hill, North Carolina, USA, The University of North Carolina at Chapel Hill, 7119 Thurston Bowles Building (104 Manning Drive), Campus Box 7352, Chapel Hill, NC, 27599-7352, United States
| | - R Jude Samulski
- Gene Therapy Center, University of North Carolina, Chapel Hill, North Carolina, USA, The University of North Carolina at Chapel Hill, 7119 Thurston Bowles Building (104 Manning Drive), Campus Box 7352, Chapel Hill, NC, 27599-7352, United States; Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina, USA, The University of North Carolina at Chapel Hill, 7119 Thurston Bowles Building (104 Manning Drive), Campus Box 7352, Chapel Hill, NC, 27599-7352, United States
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Qu W, Wang M, Wu Y, Xu R. Scalable downstream strategies for purification of recombinant adeno- associated virus vectors in light of the properties. Curr Pharm Biotechnol 2015; 16:684-95. [PMID: 25941887 PMCID: PMC5388796 DOI: 10.2174/1389201016666150505122228] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 12/30/2014] [Accepted: 04/06/2015] [Indexed: 12/27/2022]
Abstract
Recombinant adeno-associated virus (rAAV) vector is one of the promising delivery tools for gene therapy. Currently, hundreds of clinical trials are performed but the major barrier for clinical application is the absence of any ideal large scale production technique to obtain sufficient and highly pure rAAV vector. The large scale production technique includes upstream and downstream processing. The upstream processing is a vector package step and the downstream processing is a vector purification step. For large scale downstream processing, the scientists need to recover rAAV from dozens of liters of cell lysate or medium, and a variety of purification strategies have been developed but not comprehensively compared till now. Consequently, this review will evaluate the scalable downstream purification strategies systematically, especially those based on the physicochemical properties of AAV virus, and attempt to find better scalable downstream strategies for rAAV vectors.
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Affiliation(s)
| | - Mingxi Wang
- Yunleung Laboratory of Molecular Diagnostics, School of Medicine and Institute of Molecular Medicine, Huaqiao University, Quanzhou 362021, China.
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Lewis S. Gene therapy: Going from strength to strength. Nat Rev Neurosci 2014; 15:698-9. [PMID: 25301356 DOI: 10.1038/nrn3847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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