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Barbeau S, Semprez F, Dobbertin A, Merriadec L, Roussange F, Eymard B, Sternberg D, Fournier E, Karasoy H, Martinat C, Legay C. Molecular Analysis of a Congenital Myasthenic Syndrome Due to a Pathogenic Variant Affecting the C-Terminus of ColQ. Int J Mol Sci 2023; 24:16217. [PMID: 38003406 PMCID: PMC10671321 DOI: 10.3390/ijms242216217] [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: 09/29/2023] [Revised: 11/04/2023] [Accepted: 11/04/2023] [Indexed: 11/26/2023] Open
Abstract
Congenital Myasthenic Syndromes (CMSs) are rare inherited diseases of the neuromuscular junction characterized by muscle weakness. CMSs with acetylcholinesterase deficiency are due to pathogenic variants in COLQ, a collagen that anchors the enzyme at the synapse. The two COLQ N-terminal domains have been characterized as being biochemical and functional. They are responsible for the structure of the protein in the triple helix and the association of COLQ with acetylcholinesterase. To deepen the analysis of the distal C-terminal peptide properties and understand the CMSs associated to pathogenic variants in this domain, we have analyzed the case of a 32 year old male patient bearing a homozygote splice site variant c.1281 C > T that changes the sequence of the last 28 aa in COLQ. Using COS cell and mouse muscle cell expression, we show that the COLQ variant does not impair the formation of the collagen triple helix in these cells, nor its association with acetylcholinesterase, and that the hetero-oligomers are secreted. However, the interaction of COLQ variant with LRP4, a signaling hub at the neuromuscular junction, is decreased by 44% as demonstrated by in vitro biochemical methods. In addition, an increase in all acetylcholine receptor subunit mRNA levels is observed in muscle cells derived from the patient iPSC. All these approaches point to pathophysiological mechanisms essentially characterized by a decrease in signaling and the presence of immature acetylcholine receptors.
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Affiliation(s)
- Susie Barbeau
- CNRS, Saint Pères Paris Institute for the Neurosciences (SPPIN), Université Paris Cité, 75270 Paris, France
| | - Fannie Semprez
- CNRS, Saint Pères Paris Institute for the Neurosciences (SPPIN), Université Paris Cité, 75270 Paris, France
| | - Alexandre Dobbertin
- CNRS, Saint Pères Paris Institute for the Neurosciences (SPPIN), Université Paris Cité, 75270 Paris, France
| | - Laurine Merriadec
- INSERM/UEPS UMR 861, Université Paris Saclay, I-STEM, 91100 Corbeil-Essonnes, France
| | - Florine Roussange
- INSERM/UEPS UMR 861, Université Paris Saclay, I-STEM, 91100 Corbeil-Essonnes, France
| | - Bruno Eymard
- Inserm U 1127, CNRS UMR 7225, Sorbonne Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle Épinière, ICM, Sorbonne Université, 75013 Paris, France
- AP-HP, Hôpital Pitié-Salpêtrière, 75013 Paris, France
| | - Damien Sternberg
- Inserm U 1127, CNRS UMR 7225, Sorbonne Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle Épinière, ICM, Sorbonne Université, 75013 Paris, France
- AP-HP, Hôpital Pitié-Salpêtrière, 75013 Paris, France
| | - Emmanuel Fournier
- Department of Physiology, Faculté de Médecine Pitié-Salpêtrière, Sorbonne Université, 75006 Paris, France
| | - Hanice Karasoy
- Department of Neurology, Faculty of Medicine, Ege University, Izmir 35100, Turkey
| | - Cécile Martinat
- INSERM/UEPS UMR 861, Université Paris Saclay, I-STEM, 91100 Corbeil-Essonnes, France
| | - Claire Legay
- CNRS, Saint Pères Paris Institute for the Neurosciences (SPPIN), Université Paris Cité, 75270 Paris, France
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Uyen Dao TM, Barbeau S, Messéant J, Della-Gaspera B, Bouceba T, Semprez F, Legay C, Dobbertin A. The collagen ColQ binds to LRP4 and regulates the activation of the Muscle-Specific Kinase-LRP4 receptor complex by agrin at the neuromuscular junction. J Biol Chem 2023; 299:104962. [PMID: 37356721 PMCID: PMC10382678 DOI: 10.1016/j.jbc.2023.104962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 06/09/2023] [Accepted: 06/13/2023] [Indexed: 06/27/2023] Open
Abstract
Collagen Q (ColQ) is a nonfibrillar collagen that plays a crucial role at the vertebrate neuromuscular junction (NMJ) by anchoring acetylcholinesterase to the synapse. ColQ also functions in signaling, as it regulates acetylcholine receptor clustering and synaptic gene expression, in a manner dependent on muscle-specific kinase (MuSK), a key protein in NMJ formation and maintenance. MuSK forms a complex with low-density lipoprotein receptor-related protein 4 (LRP4), its coreceptor for the proteoglycan agrin at the NMJ. Previous studies suggested that ColQ also interacts with MuSK. However, the molecular mechanisms underlying ColQ functions and ColQ-MuSK interaction have not been fully elucidated. Here, we investigated whether ColQ binds directly to MuSK and/or LRP4 and whether it modulates agrin-mediated MuSK-LRP4 activation. Using coimmunoprecipitation, pull-down, plate-binding assays, and surface plasmon resonance, we show that ColQ binds directly to LRP4 but not to MuSK and that ColQ interacts indirectly with MuSK through LRP4. In addition, we show that the LRP4 N-terminal region, which contains the agrin-binding sites, is also crucial for ColQ binding to LRP4. Moreover, ColQ-LRP4 interaction was reduced in the presence of agrin, suggesting that agrin and ColQ compete for binding to LRP4. Strikingly, we reveal ColQ has two opposing effects on agrin-induced MuSK-LRP4 signaling: it constitutively reduces MuSK phosphorylation levels in agrin-stimulated myotubes but concomitantly increases MuSK accumulation at the muscle cell surface. Our results identify LRP4 as a major receptor of ColQ and provide new insights into mechanisms of ColQ signaling and acetylcholinesterase anchoring at the NMJ.
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Affiliation(s)
- Thi Minh Uyen Dao
- Université Paris Cité, CNRS, Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Susie Barbeau
- Université Paris Cité, CNRS, Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Julien Messéant
- Université Paris Cité, CNRS, Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | | | - Tahar Bouceba
- Sorbonne Université, CNRS, IBPS, Protein Engineering Platform, Paris, France
| | - Fannie Semprez
- Université Paris Cité, CNRS, Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Claire Legay
- Université Paris Cité, CNRS, Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Alexandre Dobbertin
- Université Paris Cité, CNRS, Saints-Pères Paris Institute for the Neurosciences, Paris, France.
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Prömer J, Barresi C, Herbst R. From phosphorylation to phenotype - Recent key findings on kinase regulation, downstream signaling and disease surrounding the receptor tyrosine kinase MuSK. Cell Signal 2023; 104:110584. [PMID: 36608736 DOI: 10.1016/j.cellsig.2022.110584] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/16/2022] [Accepted: 12/31/2022] [Indexed: 01/04/2023]
Abstract
Muscle-specific kinase (MuSK) is the key regulator of neuromuscular junction development. MuSK acts via several distinct pathways and is responsible for pre- and postsynaptic differentiation. MuSK is unique among receptor tyrosine kinases as activation and signaling are particularly tightly regulated. Initiation of kinase activity requires Agrin, a heparan sulphate proteoglycan derived from motor neurons, the low-density lipoprotein receptor-related protein-4 (Lrp4) and the intracellular adaptor protein Dok-7. There is a great knowledge gap between MuSK activation and downstream signaling. Recent studies using omics techniques have addressed this knowledge gap, thereby greatly contributing to a better understanding of MuSK signaling. Impaired MuSK signaling causes severe muscle weakness as described in congenital myasthenic syndromes or myasthenia gravis but the underlying pathophysiology is often unclear. This review focuses on recent advances in deciphering MuSK activation and downstream signaling. We further highlight latest break-throughs in understanding and treatment of MuSK-related disorders and discuss the role of MuSK in non-muscle tissue.
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Affiliation(s)
- Jakob Prömer
- Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Cinzia Barresi
- Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Ruth Herbst
- Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
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Shao S, Shi G, Bi FF, Huang K. Pharmacological Treatments for Congenital Myasthenic Syndromes Caused by COLQ Mutations. Curr Neuropharmacol 2023; 21:1594-1605. [PMID: 36703579 PMCID: PMC10472815 DOI: 10.2174/1570159x21666230126145652] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 09/30/2022] [Accepted: 11/18/2022] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Congenital myasthenic syndromes (CMS) refer to a series of inherited disorders caused by defects in various proteins. Mutation in the collagen-like tail subunit of asymmetric acetylcholinesterase (COLQ) is the second-most common cause of CMS. However, data on pharmacological treatments are limited. OBJECTIVE In this study, we reviewed related reports to determine the most appropriate pharmacological strategy for CMS caused by COLQ mutations. A literature review and meta-analysis were also performed. PubMed, MEDLINE, Web of Science, and Cochrane Library databases were searched to identify studies published in English before July 22, 2022. RESULTS A total of 42 studies including 164 patients with CMS due to 72 different COLQ mutations were selected for evaluation. Most studies were case reports, and none were randomized clinical trials. Our meta-analysis revealed evidence that β-adrenergic agonists, including salbutamol and ephedrine, can be used as first-line pharmacological treatments for CMS patients with COLQ mutations, as 98.7% of patients (74/75) treated with β-adrenergic agonists showed positive effects. In addition, AChEIs should be avoided in CMS patients with COLQ mutations, as 90.5% (105/116) of patients treated with AChEIs showed either no or negative effects. CONCLUSION (1) β-adrenergic agonist therapy is the first pharmacological strategy for treating CMS with COLQ mutations. (2) AChEIs should be avoided in patients with CMS with COLQ mutations.
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Affiliation(s)
- Shuai Shao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- Xiangya School of Medicine, Central South University, Changsha, Hunan province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Guanzhong Shi
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- Xiangya School of Medicine, Central South University, Changsha, Hunan province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Fang-Fang Bi
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Kun Huang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
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Boëx M, Cottin S, Halliez M, Bauché S, Buon C, Sans N, Montcouquiol M, Molgó J, Amar M, Ferry A, Lemaitre M, Rouche A, Langui D, Baskaran A, Fontaine B, Messéant J, Strochlic L. The cell polarity protein Vangl2 in the muscle shapes the neuromuscular synapse by binding to and regulating the tyrosine kinase MuSK. Sci Signal 2022; 15:eabg4982. [PMID: 35580169 DOI: 10.1126/scisignal.abg4982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The development of the neuromuscular junction (NMJ) requires dynamic trans-synaptic coordination orchestrated by secreted factors, including Wnt family morphogens. To investigate how these synaptic cues in NMJ development are transduced, particularly in the regulation of acetylcholine receptor (AChR) accumulation in the postsynaptic membrane, we explored the function of Van Gogh-like protein 2 (Vangl2), a core component of Wnt planar cell polarity signaling. We found that conditional, muscle-specific ablation of Vangl2 in mice reproduced the NMJ differentiation defects seen in mice with global Vangl2 deletion. These alterations persisted into adulthood and led to NMJ disassembly, impaired neurotransmission, and deficits in motor function. Vangl2 and the muscle-specific receptor tyrosine kinase MuSK were functionally associated in Wnt signaling in the muscle. Vangl2 bound to and promoted the signaling activity of MuSK in response to Wnt11. The loss of Vangl2 impaired RhoA activation in cultured mouse myotubes and caused dispersed, rather than clustered, organization of AChRs at the postsynaptic or muscle cell side of NMJs in vivo. Our results identify Vangl2 as a key player of the core complex of molecules shaping neuromuscular synapses and thus shed light on the molecular mechanisms underlying NMJ assembly.
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Affiliation(s)
- Myriam Boëx
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Institut de Myologie, Centre de Recherche en Myologie, Paris 75013, France
| | - Steve Cottin
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Institut de Myologie, Centre de Recherche en Myologie, Paris 75013, France
| | - Marius Halliez
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Institut de Myologie, Centre de Recherche en Myologie, Paris 75013, France
| | - Stéphanie Bauché
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Institut de Myologie, Centre de Recherche en Myologie, Paris 75013, France
| | - Céline Buon
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Institut de Myologie, Centre de Recherche en Myologie, Paris 75013, France
| | - Nathalie Sans
- Institut National de la Santé et de la Recherche Médicale, Neurocentre Magendie, UMR-S 1215, Bordeaux 33077, France.,Université Bordeaux, Neurocentre Magendie, Bordeaux, 33000, France
| | - Mireille Montcouquiol
- Institut National de la Santé et de la Recherche Médicale, Neurocentre Magendie, UMR-S 1215, Bordeaux 33077, France.,Université Bordeaux, Neurocentre Magendie, Bordeaux, 33000, France
| | - Jordi Molgó
- Université Paris-Saclay, Commissariat à l'Energie Atomique et aux énergies Alternatives, Institut des Sciences du Vivant Frédéric Joliot, Département Médicaments et Technologies pour la Santé, Equipe Mixte de Recherche CNRS 9004, Service d'Ingénierie Moléculaire pour la Santé, Gif-sur-Yvette 91191, France
| | - Muriel Amar
- Université Paris-Saclay, Commissariat à l'Energie Atomique et aux énergies Alternatives, Institut des Sciences du Vivant Frédéric Joliot, Département Médicaments et Technologies pour la Santé, Equipe Mixte de Recherche CNRS 9004, Service d'Ingénierie Moléculaire pour la Santé, Gif-sur-Yvette 91191, France
| | - Arnaud Ferry
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Institut de Myologie, Centre de Recherche en Myologie, Paris 75013, France
| | - Mégane Lemaitre
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Phénotypage du Petit Animal, Paris 75013, France
| | - Andrée Rouche
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Institut de Myologie, Centre de Recherche en Myologie, Paris 75013, France
| | - Dominique Langui
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Institut du Cerveau et de la Moelle, Plate-forme d'Imagerie Cellulaire Pitié-Salpêtrière, Paris 75013, France
| | - Asha Baskaran
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Institut du Cerveau et de la Moelle, Plate-forme d'Imagerie Cellulaire Pitié-Salpêtrière, Paris 75013, France
| | - Bertrand Fontaine
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Institut de Myologie, Centre de Recherche en Myologie, Paris 75013, France.,Assistance Publique-Hôpitaux de Paris (AP-HP) Service de Neuro-Myologie, Hôpital Universitaire Pitié-Salpêtrière, Paris 75013, France
| | - Julien Messéant
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Institut de Myologie, Centre de Recherche en Myologie, Paris 75013, France
| | - Laure Strochlic
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Institut de Myologie, Centre de Recherche en Myologie, Paris 75013, France
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Hayes AJ, Farrugia BL, Biose IJ, Bix GJ, Melrose J. Perlecan, A Multi-Functional, Cell-Instructive, Matrix-Stabilizing Proteoglycan With Roles in Tissue Development Has Relevance to Connective Tissue Repair and Regeneration. Front Cell Dev Biol 2022; 10:856261. [PMID: 35433700 PMCID: PMC9010944 DOI: 10.3389/fcell.2022.856261] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 02/28/2022] [Indexed: 12/19/2022] Open
Abstract
This review highlights the multifunctional properties of perlecan (HSPG2) and its potential roles in repair biology. Perlecan is ubiquitous, occurring in vascular, cartilaginous, adipose, lymphoreticular, bone and bone marrow stroma and in neural tissues. Perlecan has roles in angiogenesis, tissue development and extracellular matrix stabilization in mature weight bearing and tensional tissues. Perlecan contributes to mechanosensory properties in cartilage through pericellular interactions with fibrillin-1, type IV, V, VI and XI collagen and elastin. Perlecan domain I - FGF, PDGF, VEGF and BMP interactions promote embryonic cellular proliferation, differentiation, and tissue development. Perlecan domain II, an LDLR-like domain interacts with lipids, Wnt and Hedgehog morphogens. Perlecan domain III binds FGF-7 and 18 and has roles in the secretion of perlecan. Perlecan domain IV, an immunoglobulin repeat domain, has cell attachment and matrix stabilizing properties. Perlecan domain V promotes tissue repair through interactions with VEGF, VEGF-R2 and α2β1 integrin. Perlecan domain-V LG1-LG2 and LG3 fragments antagonize these interactions. Perlecan domain V promotes reconstitution of the blood brain barrier damaged by ischemic stroke and is neurogenic and neuroprotective. Perlecan-VEGF-VEGFR2, perlecan-FGF-2 and perlecan-PDGF interactions promote angiogenesis and wound healing. Perlecan domain I, III and V interactions with platelet factor-4 and megakaryocyte and platelet inhibitory receptor promote adhesion of cells to implants and scaffolds in vascular repair. Perlecan localizes acetylcholinesterase in the neuromuscular junction and is of functional significance in neuromuscular control. Perlecan mutation leads to Schwartz-Jampel Syndrome, functional impairment of the biomechanical properties of the intervertebral disc, variable levels of chondroplasia and myotonia. A greater understanding of the functional working of the neuromuscular junction may be insightful in therapeutic approaches in the treatment of neuromuscular disorders. Tissue engineering of salivary glands has been undertaken using bioactive peptides (TWSKV) derived from perlecan domain IV. Perlecan TWSKV peptide induces differentiation of salivary gland cells into self-assembling acini-like structures that express salivary gland biomarkers and secrete α-amylase. Perlecan also promotes chondroprogenitor stem cell maturation and development of pluripotent migratory stem cell lineages, which participate in diarthrodial joint formation, and early cartilage development. Recent studies have also shown that perlecan is prominently expressed during repair of adult human articular cartilage. Perlecan also has roles in endochondral ossification and bone development. Perlecan domain I hydrogels been used in tissue engineering to establish heparin binding growth factor gradients that promote cell migration and cartilage repair. Perlecan domain I collagen I fibril scaffolds have also been used as an FGF-2 delivery system for tissue repair. With the availability of recombinant perlecan domains, the development of other tissue repair strategies should emerge in the near future. Perlecan co-localization with vascular elastin in the intima, acts as a blood shear-flow endothelial sensor that regulates blood volume and pressure and has a similar role to perlecan in canalicular fluid, regulating bone development and remodeling. This complements perlecan’s roles in growth plate cartilage and in endochondral ossification to form the appendicular and axial skeleton. Perlecan is thus a ubiquitous, multifunctional, and pleomorphic molecule of considerable biological importance. A greater understanding of its diverse biological roles and functional repertoires during tissue development, growth and disease will yield valuable insights into how this impressive proteoglycan could be utilized successfully in repair biology.
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Affiliation(s)
- Anthony J. Hayes
- Bioimaging Research Hub, Cardiff School of Biosciences, Cardiff University, Wales, United Kingdom
| | - Brooke L. Farrugia
- Department of Biomedical Engineering, Melbourne School of Engineering, The University of Melbourne, Melbourne, VIC, Australia
| | - Ifechukwude J. Biose
- Departments of Neurosurgery and Neurology, Clinical Neuroscience Research Center, Tulane University School of Medicine, New Orleans, LA, United States
| | - Gregory J. Bix
- Departments of Neurosurgery and Neurology, Clinical Neuroscience Research Center, Tulane University School of Medicine, New Orleans, LA, United States
| | - James Melrose
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, Australia
- Raymond Purves Bone and Joint Research Laboratories, Kolling Institute of Medical Research, Royal North Shore Hospital, The Faculty of Medicine and Health, The University of Sydney, St. Leonard’s, NSW, Australia
- *Correspondence: James Melrose,
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Petrov KA, Proskurina SE, Krejci E. Cholinesterases in Tripartite Neuromuscular Synapse. Front Mol Neurosci 2022; 14:811220. [PMID: 35002624 PMCID: PMC8733319 DOI: 10.3389/fnmol.2021.811220] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 11/29/2021] [Indexed: 11/13/2022] Open
Abstract
The neuromuscular junction (NMJ) is a tripartite synapse in which not only presynaptic and post-synaptic cells participate in synaptic transmission, but also terminal Schwann cells (TSC). Acetylcholine (ACh) is the neurotransmitter that mediates the signal between the motor neuron and the muscle but also between the motor neuron and TSC. ACh action is terminated by acetylcholinesterase (AChE), anchored by collagen Q (ColQ) in the basal lamina of NMJs. AChE is also anchored by a proline-rich membrane anchor (PRiMA) to the surface of the nerve terminal. Butyrylcholinesterase (BChE), a second cholinesterase, is abundant on TSC and anchored by PRiMA to its plasma membrane. Genetic studies in mice have revealed different regulations of synaptic transmission that depend on ACh spillover. One of the strongest is a depression of ACh release that depends on the activation of α7 nicotinic acetylcholine receptors (nAChR). Partial AChE deficiency has been described in many pathologies or during treatment with cholinesterase inhibitors. In addition to changing the activation of muscle nAChR, AChE deficiency results in an ACh spillover that changes TSC signaling. In this mini-review, we will first briefly outline the organization of the NMJ. This will be followed by a look at the role of TSC in synaptic transmission. Finally, we will review the pathological conditions where there is evidence of decreased AChE activity.
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Affiliation(s)
- Konstantin A Petrov
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, Kazan, Russia
| | - Svetlana E Proskurina
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, Kazan, Russia
| | - Eric Krejci
- CNRS, Université de Paris, ENS Paris Saclay, Centre Borelli UMR 9010, Paris, France
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TDP-43 Regulation of AChE Expression Can Mediate ALS-Like Phenotype in Zebrafish. Cells 2021; 10:cells10020221. [PMID: 33499374 PMCID: PMC7911940 DOI: 10.3390/cells10020221] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 01/13/2021] [Accepted: 01/13/2021] [Indexed: 12/12/2022] Open
Abstract
The "distal axonopathy" hypothesis in amyotrophic lateral sclerosis (ALS) proposes that pathological changes occur at the neuromuscular junction (NMJ) early in the disease. While acetylcholinesterase (AChE) plays an important role in the functionality of the NMJ, its potential role in ALS remains unexplored. Here, we identified AChE as a limiting factor regulating muscle/motor neuron connection in a vertebrate model of ALS. Knockdown of the TAR DNA-binding protein 43 (TDP-43) orthologue in zebrafish resulted in early defects of motor functions coupled with NMJ disassembly. We found that a partially depleted tdp-43 caused a decrease of ache expression. Importantly, human AChE overexpression reduced the phenotypic defects in the tdp-43 loss of function model, with amelioration of post- and pre-synaptic deficits at the NMJ. In conclusion, our results provide a better understanding of the role of TDP-43 in the NMJ organization and indicate AChE as a contributing factor in the pathology of ALS. In particular, it may be implicated in the early defects that characterize NMJs in this major neurodegenerative disorder.
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Luo X, Wang C, Lin L, Yuan F, Wang S, Wang Y, Wang A, Wang C, Wu S, Lan X, Xu Q, Yin R, Cheng H, Zhang Y, Xi J, Zhang J, Sun X, Yan J, Zeng F, Chen Y. Mechanisms of Congenital Myasthenia Caused by Three Mutations in the COLQ Gene. Front Pediatr 2021; 9:679342. [PMID: 34912755 PMCID: PMC8667818 DOI: 10.3389/fped.2021.679342] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 11/08/2021] [Indexed: 01/12/2023] Open
Abstract
The gene encoding collagen like tail subunit of asymmetric acetylcholinesterase (COLQ) is responsible for the transcription of three strands of collagen of acetylcholinesterase, which is attached to the endplate of neuromuscular junctions. Mutations in the COLQ gene are inherited in an autosomal-recessive manner and can lead to type V congenital myasthenia syndrome (CMS), which manifests as decreased muscle strength at birth or shortly after birth, respiratory failure, restricted eye movements, drooping of eyelids, and difficulty swallowing. Here we reported three variants within COLQ in two unrelated children with CMS. An intronic variant (c.393+1G>A) and a novel missense variant (p.Q381P) were identified as compound heterozygous in a 13-month-old boy, with the parents being carriers of each. An intragenic deletion including exons 14 and 15 was found in a homozygous state in a 12-year-old boy. We studied the relative expression of the COLQ and AChE gene in the probands' families, performed three-dimensional protein structural analysis, and analyzed the conservation of the missense mutation c.1142A>C (p.Q381P). The splicing mutation c.393+1G>A was found to affect the normal splicing of COLQ exon 5, resulting in a 27-bp deletion. The missense mutation c.1142A>C (p.Q381P) was located in a conserved position in different species. We found that homozygous deletion of COLQ exons 14-15 resulted in a 241-bp deletion, which decreased the number of amino acids and caused a frameshift translation. COLQ expression was significantly lower in the probands than in the probands' parents and siblings, while AChE expression was significantly higher. Moreover, the mutations were found to cause significant differences in the predicted three-dimensional structure of the protein. The splicing mutation c.393+1G>A, missense mutation c.1A>C (p.Q381P), and COLQ exon 14-15 deletion could cause CMS.
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Affiliation(s)
- Xiaona Luo
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Chunmei Wang
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Longlong Lin
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Fang Yuan
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Simei Wang
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Yilin Wang
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Anqi Wang
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Chao Wang
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Shengnan Wu
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Xiaoping Lan
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Quanmei Xu
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Rongrong Yin
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Hongyi Cheng
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Yuanfeng Zhang
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Jiaming Xi
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Jie Zhang
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Xiaomin Sun
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China
| | - Jingbin Yan
- National Health Commission (NHC) Key Laboratory of Medical Embryogenesis and Developmental Molecular Biology and Shanghai Key Laboratory of Embryo and Reproduction Engineering, Shanghai, China
| | - Fanyi Zeng
- National Health Commission (NHC) Key Laboratory of Medical Embryogenesis and Developmental Molecular Biology and Shanghai Key Laboratory of Embryo and Reproduction Engineering, Shanghai, China
| | - Yucai Chen
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai, China.,National Health Commission (NHC) Key Laboratory of Medical Embryogenesis and Developmental Molecular Biology and Shanghai Key Laboratory of Embryo and Reproduction Engineering, Shanghai, China
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10
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Karmouch J, Delers P, Semprez F, Soyed N, Areias J, Bélanger G, Ravel-Chapuis A, Dobbertin A, Jasmin BJ, Legay C. AChR β-Subunit mRNAs Are Stabilized by HuR in a Mouse Model of Congenital Myasthenic Syndrome With Acetylcholinesterase Deficiency. Front Mol Neurosci 2020; 13:568171. [PMID: 33362463 PMCID: PMC7757417 DOI: 10.3389/fnmol.2020.568171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/13/2020] [Indexed: 11/13/2022] Open
Abstract
Collagen Q (COLQ) is a specific collagen that anchors acetylcholinesterase (AChE) in the synaptic cleft of the neuromuscular junction. So far, no mutation has been identified in the ACHE human gene but over 50 different mutations in the COLQ gene are causative for a congenital myasthenic syndrome (CMS) with AChE deficiency. Mice deficient for COLQ mimic most of the functional deficit observed in CMS patients. At the molecular level, a striking consequence of the absence of COLQ is an increase in the levels of acetylcholine receptor (AChR) mRNAs and proteins in vivo and in vitro in murine skeletal muscle cells. Here, we decipher the mechanisms that drive AChR mRNA upregulation in cultured muscle cells deficient for COLQ. We show that the levels of AChR β-subunit mRNAs are post-transcriptionally regulated by an increase in their stability. We demonstrate that this process results from an activation of p38 MAPK and the cytoplasmic translocation of the nuclear RNA-binding protein human antigen R (HuR) that interacts with the AU-rich element located within AChR β-subunit transcripts. This HuR/AChR transcript interaction induces AChR β-subunit mRNA stabilization and occurs at a specific stage of myogenic differentiation. In addition, pharmacological drugs that modulate p38 activity cause parallel modifications of HuR protein and AChR β-subunit levels. Thus, our study provides new insights into the signaling pathways that are regulated by ColQ-deficiency and highlights for the first time a role for HuR and p38 in mRNA stability in a model of congenital myasthenic syndrome.
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Affiliation(s)
- Jennifer Karmouch
- CNRS UMR 8003, Université de Paris, Sorbonne Paris Cité, Paris, France
| | - Perrine Delers
- CNRS UMR 8003, Université de Paris, Sorbonne Paris Cité, Paris, France
| | - Fannie Semprez
- CNRS UMR 8003, Université de Paris, Sorbonne Paris Cité, Paris, France
| | - Nouha Soyed
- CNRS UMR 8003, Université de Paris, Sorbonne Paris Cité, Paris, France
| | - Julie Areias
- CNRS UMR 8003, Université de Paris, Sorbonne Paris Cité, Paris, France
| | - Guy Bélanger
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Aymeric Ravel-Chapuis
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | | | - Bernard J Jasmin
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Claire Legay
- CNRS UMR 8003, Université de Paris, Sorbonne Paris Cité, Paris, France
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11
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The multiple biological roles of the cholinesterases. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 162:41-56. [PMID: 33307019 DOI: 10.1016/j.pbiomolbio.2020.12.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 11/30/2020] [Accepted: 12/03/2020] [Indexed: 12/14/2022]
Abstract
It is tacitly assumed that the biological role of acetylcholinesterase is termination of synaptic transmission at cholinergic synapses. However, together with its structural homolog, butyrylcholinesterase, it is widely distributed both within and outside the nervous system, and, in many cases, the role of both enzymes remains obscure. The transient appearance of the cholinesterases in embryonic tissues is especially enigmatic. The two enzymes' extra-synaptic roles, which are known as 'non-classical' roles, are the topic of this review. Strong evidence has been presented that AChE and BChE play morphogenetic roles in a variety of eukaryotic systems, and they do so either by acting as adhesion proteins, or as trophic factors. As trophic factors, one mode of action is to directly regulate morphogenesis, such as neurite outgrowth, by poorly understood mechanisms. The other mode is by regulating levels of acetylcholine, which acts as the direct trophic factor. Alternate substrates have been sought for the cholinesterases. Quite recently, it was shown that levels of the aggression hormone, ghrelin, which also controls appetite, are regulated by butyrylcholinesterase. The rapid hydrolysis of acetylcholine by acetylcholinesterase generates high local proton concentrations. The possible biophysical and biological consequences of this effect are discussed. The biological significance of the acetylcholinesterases secreted by parasitic nematodes is reviewed, and, finally, the involvement of acetylcholinesterase in apoptosis is considered.
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12
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Chemello F, Wang Z, Li H, McAnally JR, Liu N, Bassel-Duby R, Olson EN. Degenerative and regenerative pathways underlying Duchenne muscular dystrophy revealed by single-nucleus RNA sequencing. Proc Natl Acad Sci U S A 2020; 117:29691-29701. [PMID: 33148801 PMCID: PMC7703557 DOI: 10.1073/pnas.2018391117] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a fatal muscle disorder characterized by cycles of degeneration and regeneration of multinucleated myofibers and pathological activation of a variety of other muscle-associated cell types. The extent to which different nuclei within the shared cytoplasm of a myofiber may display transcriptional diversity and whether individual nuclei within a multinucleated myofiber might respond differentially to DMD pathogenesis is unknown. Similarly, the potential transcriptional diversity among nonmuscle cell types within dystrophic muscle has not been explored. Here, we describe the creation of a mouse model of DMD caused by deletion of exon 51 of the dystrophin gene, which represents a prevalent disease-causing mutation in humans. To understand the transcriptional abnormalities and heterogeneity associated with myofiber nuclei, as well as other mononucleated cell types that contribute to the muscle pathology associated with DMD, we performed single-nucleus transcriptomics of skeletal muscle of mice with dystrophin exon 51 deletion. Our results reveal distinctive and previously unrecognized myonuclear subtypes within dystrophic myofibers and uncover degenerative and regenerative transcriptional pathways underlying DMD pathogenesis. Our findings provide insights into the molecular underpinnings of DMD, controlled by the transcriptional activity of different types of muscle and nonmuscle nuclei.
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Affiliation(s)
- Francesco Chemello
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Zhaoning Wang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Hui Li
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - John R McAnally
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Ning Liu
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Rhonda Bassel-Duby
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Eric N Olson
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390;
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
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13
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Brooks PJ, Ottinger EA, Portero D, Lomash RM, Alimardanov A, Terse P, Xu X, Chandler RJ, Geist Hauserman J, Esposito E, Bönnemann CG, Venditti CP, Austin CP, Pariser A, Lo DC. The Platform Vector Gene Therapies Project: Increasing the Efficiency of Adeno-Associated Virus Gene Therapy Clinical Trial Startup. Hum Gene Ther 2020; 31:1034-1042. [PMID: 32993373 PMCID: PMC7585601 DOI: 10.1089/hum.2020.259] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- Philip J Brooks
- Office of Rare Disease Research, National Center for Advancing Translational Sciences (NCATS)
| | - Elizabeth A Ottinger
- Therapeutic Development Branch, National Center for Advancing Translational Sciences (NCATS)
| | - Deanna Portero
- Office of Rare Disease Research, National Center for Advancing Translational Sciences (NCATS)
| | - Richa Madan Lomash
- Therapeutic Development Branch, National Center for Advancing Translational Sciences (NCATS)
| | - Asaf Alimardanov
- Therapeutic Development Branch, National Center for Advancing Translational Sciences (NCATS)
| | - Pramod Terse
- Therapeutic Development Branch, National Center for Advancing Translational Sciences (NCATS)
| | - Xin Xu
- Therapeutic Development Branch, National Center for Advancing Translational Sciences (NCATS)
| | - Randy J Chandler
- Organic Acid Research Section, Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute (NHGRI)
| | - Janelle Geist Hauserman
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke (NINDS); National Institutes of Health, Bethesda, Maryland, USA
| | - Eric Esposito
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke (NINDS); National Institutes of Health, Bethesda, Maryland, USA
| | - Carsten G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke (NINDS); National Institutes of Health, Bethesda, Maryland, USA
| | - Charles P Venditti
- Organic Acid Research Section, Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute (NHGRI)
| | - Christopher P Austin
- Office of the Director, National Center for Advancing Translational Sciences (NCATS)
| | - Anne Pariser
- Office of Rare Disease Research, National Center for Advancing Translational Sciences (NCATS)
| | - Donald C Lo
- Therapeutic Development Branch, National Center for Advancing Translational Sciences (NCATS)
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14
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Pohanka M. Diagnoses of Pathological States Based on Acetylcholinesterase and Butyrylcholinesterase. Curr Med Chem 2020; 27:2994-3011. [PMID: 30706778 DOI: 10.2174/0929867326666190130161202] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 01/16/2019] [Accepted: 01/17/2019] [Indexed: 12/15/2022]
Abstract
Two cholinesterases exist: Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). While AChE plays a crucial role in neurotransmissions, BChE has no specific function apart from the detoxification of some drugs and secondary metabolites from plants. Thus, both AChE and BChE can serve as biochemical markers of various pathologies. Poisoning by nerve agents like sarin, soman, tabun, VX, novichok and overdosing by drugs used in some neurodegenerative disorders like Alzheimer´s disease and myasthenia gravis, as well as poisoning by organophosphorus pesticides are relevant to this issue. But it appears that changes in these enzymes take place in other processes including oxidative stress, inflammation, some types of cancer and genetically conditioned diseases. In this review, the cholinesterases are introduced, the mechanism of inhibitors action is explained and the relations between the cholinesterases and pathologies are explained.
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Affiliation(s)
- Miroslav Pohanka
- Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 50001 Hradec Kralove, Czech Republic
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15
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Collagens at the vertebrate neuromuscular junction, from structure to pathologies. Neurosci Lett 2020; 735:135155. [PMID: 32534096 DOI: 10.1016/j.neulet.2020.135155] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 06/05/2020] [Accepted: 06/09/2020] [Indexed: 12/17/2022]
Abstract
The extracellular matrix at the neuromuscular junction is built upon components secreted by the motoneuron, the muscle cell and terminal Schwann cells, the cells constituting this specific synapse. This compartment contains glycoproteins, proteoglycans and collagens that form a dense and specialized layer, the synaptic basal lamina. A number of these molecules are known to play a crucial role in anterograde and retrograde signalings that are active in neuromuscular junction formation, maintenance and function. Here, we focus on the isoforms of collagens which are enriched at the synapse. We summarize what we know of their structure, their function and their interactions with transmembrane receptors and other components of the synaptic basal lamina. A number of neuromuscular diseases, congenital myastenic syndromes and myasthenia gravis are caused by human mutations and autoantibodies against these proteins. Analysis of these diseases and of the specific collagen knock-out mice highlights the roles of some of these collagens in promoting a functional synapse.
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16
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Abstract
Thirty to fifty percent of patients with acetylcholine receptor (AChR) antibody (Ab)-negative myasthenia gravis (MG) have Abs to muscle specific kinase (MuSK) and are referred to as having MuSK-MG. MuSK is a 100 kD single-pass post-synaptic transmembrane receptor tyrosine kinase crucial to the development and maintenance of the neuromuscular junction. The Abs in MuSK-MG are predominantly of the IgG4 immunoglobulin subclass. MuSK-MG differs from AChR-MG, in exhibiting more focal muscle involvement, including neck, shoulder, facial and bulbar-innervated muscles, as well as wasting of the involved muscles. MuSK-MG is highly associated with the HLA DR14-DQ5 haplotype and occurs predominantly in females with onset in the fourth decade of life. Some of the standard treatments of AChR-MG have been found to have limited effectiveness in MuSK-MG, including thymectomy and cholinesterase inhibitors. Therefore, current treatment involves immunosuppression, primarily by corticosteroids. In addition, patients respond especially well to B cell depletion agents, e.g., rituximab, with long-term remissions. Future treatments will likely derive from the ongoing analysis of the pathogenic mechanisms underlying this disease, including histologic and physiologic studies of the neuromuscular junction in patients as well as information derived from the development and study of animal models of the disease.
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Affiliation(s)
| | - David P. Richman
- Department of Neurology, University of California, Davis, Davis, CA, United States
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17
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Thanasomboon R, Kalapanulak S, Netrphan S, Saithong T. Exploring dynamic protein-protein interactions in cassava through the integrative interactome network. Sci Rep 2020; 10:6510. [PMID: 32300157 PMCID: PMC7162878 DOI: 10.1038/s41598-020-63536-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 04/01/2020] [Indexed: 01/01/2023] Open
Abstract
Protein-protein interactions (PPIs) play an essential role in cellular regulatory processes. Despite, in-depth studies to uncover the mystery of PPI-mediated regulations are still lacking. Here, an integrative interactome network (MePPI-Ux) was obtained by incorporating expression data into the improved genome-scale interactome network of cassava (MePPI-U). The MePPI-U, constructed by both interolog- and domain-based approaches, contained 3,638,916 interactions and 24,590 proteins (59% of proteins in the cassava AM560 genome version 6). After incorporating expression data as information of state, the MePPI-U rewired to represent condition-dependent PPIs (MePPI-Ux), enabling us to envisage dynamic PPIs (DPINs) that occur at specific conditions. The MePPI-Ux was exploited to demonstrate timely PPIs of cassava under various conditions, namely drought stress, brown streak virus (CBSV) infection, and starch biosynthesis in leaf/root tissues. MePPI-Uxdrought and MePPI-UxCBSV suggested involved PPIs in response to stress. MePPI-UxSB,leaf and MePPI-UxSB,root suggested the involvement of interactions among transcription factor proteins in modulating how leaf or root starch is synthesized. These findings deepened our knowledge of the regulatory roles of PPIs in cassava and would undeniably assist targeted breeding efforts to improve starch quality and quantity.
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Affiliation(s)
- Ratana Thanasomboon
- Biological Engineering Program, Faculty of Engineering, King Mongkut's University of Technology Thonburi, Bangkok, 10140, Thailand.,Center for Agricultural Systems Biology, Systems Biology and Bioinformatics Research Group, Pilot Plant Development and Training Institute, King Mongkut's University of Technology Thonburi (Bang Khun Thian), Bangkok, 10150, Thailand
| | - Saowalak Kalapanulak
- Center for Agricultural Systems Biology, Systems Biology and Bioinformatics Research Group, Pilot Plant Development and Training Institute, King Mongkut's University of Technology Thonburi (Bang Khun Thian), Bangkok, 10150, Thailand.,Bioinformatics and Systems Biology Program, School of Bioresources and Technology, King Mongkut's University of Technology Thonburi (Bang Khun Thian), Bangkok, 10150, Thailand
| | - Supatcharee Netrphan
- National Center for Genetic Engineering and Biotechnology, Pathum Thani, 12120, Thailand
| | - Treenut Saithong
- Center for Agricultural Systems Biology, Systems Biology and Bioinformatics Research Group, Pilot Plant Development and Training Institute, King Mongkut's University of Technology Thonburi (Bang Khun Thian), Bangkok, 10150, Thailand. .,Bioinformatics and Systems Biology Program, School of Bioresources and Technology, King Mongkut's University of Technology Thonburi (Bang Khun Thian), Bangkok, 10150, Thailand.
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18
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Mukund K, Subramaniam S. Skeletal muscle: A review of molecular structure and function, in health and disease. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2020; 12:e1462. [PMID: 31407867 PMCID: PMC6916202 DOI: 10.1002/wsbm.1462] [Citation(s) in RCA: 216] [Impact Index Per Article: 54.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 07/03/2019] [Accepted: 07/03/2019] [Indexed: 12/11/2022]
Abstract
Decades of research in skeletal muscle physiology have provided multiscale insights into the structural and functional complexity of this important anatomical tissue, designed to accomplish the task of generating contraction, force and movement. Skeletal muscle can be viewed as a biomechanical device with various interacting components including the autonomic nerves for impulse transmission, vasculature for efficient oxygenation, and embedded regulatory and metabolic machinery for maintaining cellular homeostasis. The "omics" revolution has propelled a new era in muscle research, allowing us to discern minute details of molecular cross-talk required for effective coordination between the myriad interacting components for efficient muscle function. The objective of this review is to provide a systems-level, comprehensive mapping the molecular mechanisms underlying skeletal muscle structure and function, in health and disease. We begin this review with a focus on molecular mechanisms underlying muscle tissue development (myogenesis), with an emphasis on satellite cells and muscle regeneration. We next review the molecular structure and mechanisms underlying the many structural components of the muscle: neuromuscular junction, sarcomere, cytoskeleton, extracellular matrix, and vasculature surrounding muscle. We highlight aberrant molecular mechanisms and their possible clinical or pathophysiological relevance. We particularly emphasize the impact of environmental stressors (inflammation and oxidative stress) in contributing to muscle pathophysiology including atrophy, hypertrophy, and fibrosis. This article is categorized under: Physiology > Mammalian Physiology in Health and Disease Developmental Biology > Developmental Processes in Health and Disease Models of Systems Properties and Processes > Cellular Models.
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Affiliation(s)
- Kavitha Mukund
- Department of BioengineeringUniversity of CaliforniaSan DiegoCalifornia
| | - Shankar Subramaniam
- Department of Bioengineering, Bioinformatics & Systems BiologyUniversity of CaliforniaSan DiegoCalifornia
- Department of Computer Science and EngineeringUniversity of CaliforniaSan DiegoCalifornia
- Department of Cellular and Molecular Medicine and NanoengineeringUniversity of CaliforniaSan DiegoCalifornia
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19
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Lai TKY, Zhai D, Su P, Jiang A, Boychuk J, Liu F. The receptor-receptor interaction between mGluR1 receptor and NMDA receptor: a potential therapeutic target for protection against ischemic stroke. FASEB J 2019; 33:14423-14439. [DOI: 10.1096/fj.201900417r] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Terence K. Y. Lai
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Dongxu Zhai
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Ping Su
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Anlong Jiang
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Jay Boychuk
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Fang Liu
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
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20
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Camilleri M, Sandler RS, Peery AF. Etiopathogenetic Mechanisms in Diverticular Disease of the Colon. Cell Mol Gastroenterol Hepatol 2019; 9:15-32. [PMID: 31351939 PMCID: PMC6881605 DOI: 10.1016/j.jcmgh.2019.07.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 07/17/2019] [Accepted: 07/18/2019] [Indexed: 02/08/2023]
Abstract
This article reviews epidemiological evidence of heritability and putative mechanisms in diverticular disease, with greatest attention to 3 recent studies of genetic associations with diverticular disease based on genome-wide or whole-genome sequencing studies in large patient cohorts. We provide an analysis of the biological plausibility of the significant associations with gene variants reported and highlight the relevance of ANO1, CPI-17 (aka PPP1R14A), COLQ6, COL6A1, CALCB or CALCA, COL6A1, ARHGAP15, and S100A10 to colonic neuromuscular function and tissue properties that may result in altered compliance and predispose to the development of diverticular disease. Such studies also identify candidate genes for future studies.
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Affiliation(s)
- Michael Camilleri
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
| | - Robert S Sandler
- Center for Gastrointestinal Biology and Disease, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Anne F Peery
- Center for Gastrointestinal Biology and Disease, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
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21
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McMacken GM, Spendiff S, Whittaker RG, O’Connor E, Howarth RM, Boczonadi V, Horvath R, Slater CR, Lochmüller H. Salbutamol modifies the neuromuscular junction in a mouse model of ColQ myasthenic syndrome. Hum Mol Genet 2019; 28:2339-2351. [PMID: 31220253 PMCID: PMC6606850 DOI: 10.1093/hmg/ddz059] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 03/14/2019] [Accepted: 03/15/2019] [Indexed: 12/23/2022] Open
Abstract
The β-adrenergic agonists salbutamol and ephedrine have proven to be effective as therapies for human disorders of the neuromuscular junction, in particular many subsets of congenital myasthenic syndromes. However, the mechanisms underlying this clinical benefit are unknown and improved understanding of the effect of adrenergic signalling on the neuromuscular junction is essential to facilitate the development of more targeted therapies. Here, we investigated the effect of salbutamol treatment on the neuromuscular junction in the ColQ deficient mouse, a model of end-plate acetylcholinesterase deficiency. ColQ-/- mice received 7 weeks of daily salbutamol injection, and the effect on muscle strength and neuromuscular junction morphology was analysed. We show that salbutamol leads to a gradual improvement in muscle strength in ColQ-/- mice. In addition, the neuromuscular junctions of salbutamol treated mice showed significant improvements in several postsynaptic morphological defects, including increased synaptic area, acetylcholine receptor area and density, and extent of postjunctional folds. These changes occurred without alterations in skeletal muscle fibre size or type. These findings suggest that β-adrenergic agonists lead to functional benefit in the ColQ-/- mouse and to long-term structural changes at the neuromuscular junction. These effects are primarily at the postsynaptic membrane and may lead to enhanced neuromuscular transmission.
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Affiliation(s)
- Grace M McMacken
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, UK
| | - Sally Spendiff
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, UK
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada
| | - Roger G Whittaker
- Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne, UK
| | - Emily O’Connor
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, UK
| | - Rachel M Howarth
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, UK
| | - Veronika Boczonadi
- Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne, UK
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Clarke R Slater
- Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne, UK
| | - Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada
- Department of Neuropediatrics and Muscle Disorders, Medical Center – University of Freiburg, Faculty of Medicine, Freiburg, Germany
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
- Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Canada
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22
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Legay C. Congenital myasthenic syndromes with acetylcholinesterase deficiency, the pathophysiological mechanisms. Ann N Y Acad Sci 2019; 1413:104-110. [PMID: 29405353 DOI: 10.1111/nyas.13595] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 12/12/2017] [Accepted: 12/12/2017] [Indexed: 12/15/2022]
Abstract
The neuromuscular junction (NMJ) is a cholinergic synapse in vertebrates. This synapse connects motoneurons to muscles and is responsible for muscle contraction, a physiological process that is essential for survival. A key factor for the normal functioning of this synapse is the regulation of acetylcholine (ACh) levels in the synaptic cleft. This is ensured by acetylcholinesterase (AChE), which degrades ACh. A number of mutations in synaptic genes expressed in motoneurons or muscle cells have been identified and are causative for a class of neuromuscular diseases called congenital myasthenic syndromes (CMSs). One of these CMSs is due to deficiency in AChE, which is absent or diffuse in the synaptic cleft. Here, I focus on the origins of the syndrome. The role of ColQ, a collagen that anchors AChE in the synaptic cleft, is discussed in this context. Studies performed on patient biopsies, transgenic mice, and muscle cultures have provided a more comprehensive view of the connectome at the NMJ that should be useful for understanding the differences in the symptoms observed in specific CMSs due to mutated proteins in the synaptic cleft.
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Affiliation(s)
- Claire Legay
- CNRS 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
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23
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Heikkinen A, Härönen H, Norman O, Pihlajaniemi T. Collagen XIII and Other ECM Components in the Assembly and Disease of the Neuromuscular Junction. Anat Rec (Hoboken) 2019; 303:1653-1663. [PMID: 30768864 DOI: 10.1002/ar.24092] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 08/17/2018] [Accepted: 09/27/2018] [Indexed: 12/15/2022]
Abstract
Alongside playing structural roles, the extracellular matrix (ECM) acts as an interaction platform for cellular homeostasis, organ development, and maintenance. The necessity of the ECM is highlighted by the diverse, sometimes very serious diseases that stem from defects in its components. The neuromuscular junction (NMJ) is a large peripheral motor synapse differing from its central counterparts through the ECM included at the synaptic cleft. Such synaptic basal lamina (BL) is specialized to support NMJ establishment, differentiation, maturation, stabilization, and function and diverges in molecular composition from the extrasynaptic ECM. Mutations, toxins, and autoantibodies may compromise NMJ integrity and function, thereby leading to congenital myasthenic syndromes (CMSs), poisoning, and autoimmune diseases, respectively, and all these conditions may involve synaptic ECM molecules. With neurotransmission degraded or blocked, muscle function is impaired or even prevented. At worst, this can be fatal. The article reviews the synaptic BL composition required for assembly and function of the NMJ molecular machinery through the lens of studies primarily with mouse models but also with human patients. In-depth focus is given to collagen XIII, a postsynaptic-membrane-spanning but also shed ECM protein that in recent years has been revealed to be a significant component for the NMJ. Its deficiency in humans causes CMS, and autoantibodies against it have been recognized in autoimmune myasthenia gravis. Mouse models have exposed numerous details that appear to recapitulate human NMJ phenotypes relatively faithfully and thereby can be readily used to generate information necessary for understanding and ultimately treating human diseases. Anat Rec, 2019. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Anne Heikkinen
- Oulu Center for Cell-Matrix Research, Biocenter Oulu, Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Heli Härönen
- Oulu Center for Cell-Matrix Research, Biocenter Oulu, Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Oula Norman
- Oulu Center for Cell-Matrix Research, Biocenter Oulu, Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Taina Pihlajaniemi
- Oulu Center for Cell-Matrix Research, Biocenter Oulu, Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
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24
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O'Connor E, Töpf A, Zahedi RP, Spendiff S, Cox D, Roos A, Lochmüller H. Clinical and research strategies for limb-girdle congenital myasthenic syndromes. Ann N Y Acad Sci 2018; 1412:102-112. [PMID: 29315608 DOI: 10.1111/nyas.13520] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/05/2017] [Accepted: 09/12/2017] [Indexed: 12/21/2022]
Abstract
Congenital myasthenic syndromes (CMS) are a group of rare disorders that cause fatigable muscle weakness due to defective signal transmission at the neuromuscular junction, a specialized synapse between peripheral motor neurons and their target muscle fibers. There are now over 30 causative genes that have been reported for CMS. Of these, there are 10 that are associated with a limb-girdle pattern of muscle weakness and are thus classed as LG-CMS. Next-generation sequencing and advanced methods of data sharing are likely to uncover further genes that are associated with similar clinical phenotypes, contributing to better diagnosis and effective treatment of LG-CMS patients. This review highlights clinical and pathological hallmarks of LG-CMS in relation to the underlying genetic defects and pathways. Tailored animal and cell models are essential to elucidate the exact function and pathomechanisms at the neuromuscular synapse that underlie LG-CMS. The integration of genomics and proteomics data derived from these models and patients reveals new and often unexpected insights that are relevant beyond the rare genetic disorder of LG-CMS and may extend to the functioning of mammalian synapses in health and disease more generally.
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Affiliation(s)
- Emily O'Connor
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Ana Töpf
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - René P Zahedi
- Leibniz-Institut für Analytische Wissenschaften, ISAS e.V., Dortmund, Germany
| | - Sally Spendiff
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Daniel Cox
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Andreas Roos
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.,Leibniz-Institut für Analytische Wissenschaften, ISAS e.V., Dortmund, Germany
| | - Hanns Lochmüller
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
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25
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Ghazanfari N, Trajanovska S, Morsch M, Liang SX, Reddel SW, Phillips WD. The mouse passive-transfer model of MuSK myasthenia gravis: disrupted MuSK signaling causes synapse failure. Ann N Y Acad Sci 2017; 1412:54-61. [DOI: 10.1111/nyas.13513] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 09/05/2017] [Accepted: 09/09/2017] [Indexed: 12/21/2022]
Affiliation(s)
- Nazanin Ghazanfari
- 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
| | - Simon X. Liang
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences; Liaoning Medical University; Jinzhou 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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26
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Ohno K, Ohkawara B, Ito M. Agrin-LRP4-MuSK signaling as a therapeutic target for myasthenia gravis and other neuromuscular disorders. Expert Opin Ther Targets 2017; 21:949-958. [PMID: 28825343 DOI: 10.1080/14728222.2017.1369960] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Signal transduction at the neuromuscular junction (NMJ) is compromised in a diverse array of diseases including myasthenia gravis, Lambert-Eaton myasthenic syndrome, Isaacs' syndrome, congenital myasthenic syndromes, Fukuyama-type congenital muscular dystrophy, amyotrophic lateral sclerosis, and sarcopenia. Except for sarcopenia, all are orphan diseases. In addition, the NMJ signal transduction is impaired by tetanus, botulinum, curare, α-bungarotoxin, conotoxins, organophosphate, sarin, VX, and soman to name a few. Areas covered: This review covers the agrin-LRP4-MuSK signaling pathway, which drives clustering of acetylcholine receptors (AChRs) and ensures efficient signal transduction at the NMJ. We also address diseases caused by autoantibodies against the NMJ molecules and by germline mutations in genes encoding the NMJ molecules. Expert opinion: Representative small compounds to treat the defective NMJ signal transduction are cholinesterase inhibitors, which exert their effects by increasing the amount of acetylcholine at the synaptic space. Another possible therapeutic strategy to enhance the NMJ signal transduction is to increase the number of AChRs, but no currently available drug has this functionality.
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Affiliation(s)
- Kinji Ohno
- a Division of Neurogenetics , Nagoya University Graduate School of Medicine , Nagoya , Japan
| | - Bisei Ohkawara
- a Division of Neurogenetics , Nagoya University Graduate School of Medicine , Nagoya , Japan
| | - Mikako Ito
- a Division of Neurogenetics , Nagoya University Graduate School of Medicine , Nagoya , Japan
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27
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Messéant J, Ezan J, Delers P, Glebov K, Marchiol C, Lager F, Renault G, Tissir F, Montcouquiol M, Sans N, Legay C, Strochlic L. Wnt proteins contribute to neuromuscular junction formation through distinct signaling pathways. Development 2017; 144:1712-1724. [PMID: 28348167 DOI: 10.1242/dev.146167] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 03/20/2017] [Indexed: 01/05/2023]
Abstract
Understanding the developmental steps that shape formation of the neuromuscular junction (NMJ) connecting motoneurons to skeletal muscle fibers is crucial. Wnt morphogens are key players in the formation of this specialized peripheral synapse, but their individual and collaborative functions and downstream pathways remain poorly understood at the NMJ. Here, we demonstrate through Wnt4 and Wnt11 gain-of-function studies in cell culture or in mice that Wnts enhance acetylcholine receptor (AChR) clustering and motor axon outgrowth. By contrast, loss of Wnt11 or Wnt-dependent signaling in vivo decreases AChR clustering and motor nerve terminal branching. Both Wnt4 and Wnt11 stimulate AChR mRNA levels and AChR clustering downstream of activation of the β-catenin pathway. Strikingly, Wnt4 and Wnt11 co-immunoprecipitate with Vangl2, a core component of the planar cell polarity (PCP) pathway, which accumulates at embryonic NMJs. Moreover, mice bearing a Vangl2 loss-of-function mutation (loop-tail) exhibit fewer AChR clusters and overgrowth of motor axons bypassing AChR clusters. Together, our results provide genetic and biochemical evidence that Wnt4 and Wnt11 cooperatively contribute to mammalian NMJ formation through activation of both the canonical and Vangl2-dependent core PCP pathways.
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Affiliation(s)
- Julien Messéant
- CNRS UMR 8119, CNRS UMR 8194, Université Paris Descartes, PRES Sorbonne Paris Cité, Paris 75270 Cedex 06, France
| | - Jérôme Ezan
- INSERM, Neurocentre Magendie, U1215, Bordeaux 33077, France.,Université de Bordeaux, Neurocentre Magendie, U1215, Bordeaux 33077, France
| | - Perrine Delers
- CNRS UMR 8119, CNRS UMR 8194, Université Paris Descartes, PRES Sorbonne Paris Cité, Paris 75270 Cedex 06, France
| | - Konstantin Glebov
- INSERM, Neurocentre Magendie, U1215, Bordeaux 33077, France.,Université de Bordeaux, Neurocentre Magendie, U1215, Bordeaux 33077, France
| | - Carmen Marchiol
- INSERM U1016, Institut Cochin, Université Paris Descartes, PRES Sorbonne Paris Cité, Paris 75014, France
| | - Franck Lager
- INSERM U1016, Institut Cochin, Université Paris Descartes, PRES Sorbonne Paris Cité, Paris 75014, France
| | - Gilles Renault
- INSERM U1016, Institut Cochin, Université Paris Descartes, PRES Sorbonne Paris Cité, Paris 75014, France
| | - Fadel Tissir
- Université Catholique de Louvain, Institute of Neuroscience, Brussels B1200, Belgium
| | - Mireille Montcouquiol
- INSERM, Neurocentre Magendie, U1215, Bordeaux 33077, France.,Université de Bordeaux, Neurocentre Magendie, U1215, Bordeaux 33077, France
| | - Nathalie Sans
- INSERM, Neurocentre Magendie, U1215, Bordeaux 33077, France.,Université de Bordeaux, Neurocentre Magendie, U1215, Bordeaux 33077, France
| | - Claire Legay
- CNRS UMR 8119, CNRS UMR 8194, Université Paris Descartes, PRES Sorbonne Paris Cité, Paris 75270 Cedex 06, France
| | - Laure Strochlic
- CNRS UMR 8119, CNRS UMR 8194, Université Paris Descartes, PRES Sorbonne Paris Cité, Paris 75270 Cedex 06, France
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28
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Härönen H, Zainul Z, Tu H, Naumenko N, Sormunen R, Miinalainen I, Shakirzyanova A, Oikarainen T, Abdullin A, Martin P, Santoleri S, Koistinaho J, Silman I, Giniatullin R, Fox MA, Heikkinen A, Pihlajaniemi T. Collagen XIII secures pre- and postsynaptic integrity of the neuromuscular synapse. Hum Mol Genet 2017; 26:2076-2090. [DOI: 10.1093/hmg/ddx101] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 03/10/2017] [Indexed: 01/01/2023] Open
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29
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Campanari ML, García-Ayllón MS, Ciura S, Sáez-Valero J, Kabashi E. Neuromuscular Junction Impairment in Amyotrophic Lateral Sclerosis: Reassessing the Role of Acetylcholinesterase. Front Mol Neurosci 2016; 9:160. [PMID: 28082868 PMCID: PMC5187284 DOI: 10.3389/fnmol.2016.00160] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 12/12/2016] [Indexed: 01/13/2023] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a highly debilitating disease caused by progressive degeneration of motorneurons (MNs). Due to the wide variety of genes and mutations identified in ALS, a highly varied etiology could ultimately converge to produce similar clinical symptoms. A major hypothesis in ALS research is the “distal axonopathy” with pathological changes occurring at the neuromuscular junction (NMJ), at very early stages of the disease, prior to MNs degeneration and onset of clinical symptoms. The NMJ is a highly specialized cholinergic synapse, allowing signaling between muscle and nerve necessary for skeletal muscle function. This nerve-muscle contact is characterized by the clustering of the collagen-tailed form of acetylcholinesterase (ColQ-AChE), together with other components of the extracellular matrix (ECM) and specific key molecules in the NMJ formation. Interestingly, in addition to their cholinergic role AChE is thought to play several “non-classical” roles that do not require catalytic function, most prominent among these is the facilitation of neurite growth, NMJ formation and survival. In all this context, abnormalities of AChE content have been found in plasma of ALS patients, in which AChE changes may reflect the neuromuscular disruption. We review these findings and particularly the evidences of changes of AChE at neuromuscular synapse in the pre-symptomatic stages of ALS.
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Affiliation(s)
- Maria-Letizia Campanari
- Sorbonne Université, Université Pierre et Marie Curie (UPMC), Université de Paris 06, Unité Mixte 75, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 1127, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 7225 Institut du Cerveau et de la Moelle Épinière (ICM) Paris, France
| | - María-Salud García-Ayllón
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'AlacantSpain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)Madrid, Spain; Unidad de Investigación, Hospital General Universitario de Elche, FISABIOElche, Spain
| | - Sorana Ciura
- Sorbonne Université, Université Pierre et Marie Curie (UPMC), Université de Paris 06, Unité Mixte 75, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 1127, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 7225 Institut du Cerveau et de la Moelle Épinière (ICM) Paris, France
| | - Javier Sáez-Valero
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'AlacantSpain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)Madrid, Spain
| | - Edor Kabashi
- Sorbonne Université, Université Pierre et Marie Curie (UPMC), Université de Paris 06, Unité Mixte 75, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 1127, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 7225 Institut du Cerveau et de la Moelle Épinière (ICM) Paris, France
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30
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Ohno K, Ohkawara B, Ito M. Recent advances in congenital myasthenic syndromes. ACTA ACUST UNITED AC 2016. [DOI: 10.1111/cen3.12316] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics; Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Bisei Ohkawara
- Division of Neurogenetics; Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Mikako Ito
- Division of Neurogenetics; Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
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31
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Ohno K, Otsuka K, Ito M. Roles of collagen Q in MuSK antibody-positive myasthenia gravis. Chem Biol Interact 2016; 259:266-270. [PMID: 27119269 DOI: 10.1016/j.cbi.2016.04.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 02/25/2016] [Accepted: 04/11/2016] [Indexed: 10/21/2022]
Abstract
The low-density lipoprotein receptor-related protein 4 (LRP4) and the muscle-specific receptor tyrosine kinase (MuSK) form a tetrameric protein complex on the postsynaptic membrane at the neuromuscular junction (NMJ). Binding of agrin to LRP4 triggers phosphorylation of MuSK. Activated MuSK drives clustering of acetylcholine receptor (AChR). Wnt ligands also directly bind to MuSK to induce AChR clustering. MuSK anchors the acetylcholinesterase (AChE)/collagen Q (ColQ) complex to the synaptic basal lamina. In addition, an extracellular proteoglycan, biglycan, binds to MuSK. Anti-MuSK autoantibodies (MuSK-IgG) are observed in 5-15% of autoimmune myasthenia gravis (MG) patients. MuSK-IgG blocks both ColQ-MuSK and LRP4-MuSK interactions. MuSK-IgG, LRP4, ColQ, and biglycan bind to the immunoglobulin-like domains 1 and 4 of MuSK. Lack of the effects of cholinesterase inhibitors in MuSK-MG patients is likely due to hindrance of ColQ-MuSK interaction by MuSK-IgG and subsequent deficiency of AChE observed in model mice, which, however, has not been proven in MuSK-MG patients. As ColQ enhances expression of membrane-bound MuSK, inhibition of ColQ-MuSK interaction by MuSK-IgG may account for lack of AChR clusters in MuSK-MG. We thus made passive transfer models using Colq+/+ and Colq-/- mice to dissect the effect of ColQ on AChR clustering in MuSK-MG. We found that MuSK-IgG-mediated suppression of LRP4-MuSK interaction, not of ColQ-MuSK interaction, caused defective AChR clustering. We also unexpectedly observed that both MuSK-IgG and ColQ suppressed agrin/LRP4/MuSK signaling in dose-dependent manners. Quantitative comparison revealed that MuSK-IgG blocked agrin-LRP4-MuSK signaling more than ColQ. We propose that attenuation of AChR clustering in MuSK-MG is due to hindrance of LRP4-MuSK interaction in the presence of agrin by MuSK-IgG.
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Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-Ku, Nagoya 466-8550, Japan.
| | - Kenji Otsuka
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-Ku, Nagoya 466-8550, Japan
| | - Mikako Ito
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-Ku, Nagoya 466-8550, Japan
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32
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Sigoillot SM, Bourgeois F, Karmouch J, Molgó J, Dobbertin A, Chevalier C, Houlgatte R, Léger J, Legay C. Neuromuscular junction immaturity and muscle atrophy are hallmarks of the ColQ-deficient mouse, a model of congenital myasthenic syndrome with acetylcholinesterase deficiency. FASEB J 2016; 30:2382-99. [PMID: 26993635 DOI: 10.1096/fj.201500162] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 02/26/2016] [Indexed: 12/13/2022]
Abstract
The collagen ColQ anchors acetylcholinesterase (AChE) in the synaptic cleft of the neuromuscular junction (NMJ). It also binds MuSK and perlecan/dystroglycan, 2 signaling platforms of the postsynaptic domain. Mutations in ColQ cause a congenital myasthenic syndrome (CMS) with AChE deficiency. Because the absence of AChE does not fully explain the complexity of the syndrome and there is no curative treatment for the disease, we explored additional potential targets of ColQ by conducting a large genetic screening of ColQ-deficient mice, a model for CMS with AChE deficiency, and analyzed their NMJ and muscle phenotypes. We demonstrated that ColQ controls the development and the maturation of the postsynaptic domain by regulating synaptic gene expression. Notably, ColQ deficiency leads to an up-regulation of the 5 subunits of the nicotinic acetylcholine receptor (AChR), leading to mixed mature and immature AChRs at the NMJ of adult mice. ColQ also regulates the expression of extracellular matrix (ECM) components. However, whereas the ECM mRNAs were down-regulated in vitro, compensation seemed to occur in vivo to maintain normal levels of these mRNAs. Finally, ColQ deficiency leads to a general atrophic phenotype and hypoplasia that affect fast muscles. This study points to new specific hallmarks for this CMS.-Sigoillot, S. M., Bourgeois, F., Karmouch, J., Molgó, J., Dobbertin, A., Chevalier, C., Houlgatte, R., Léger, J., Legay, C. Neuromuscular junction immaturity and muscle atrophy are hallmarks of the ColQ-deficient mouse, a model of congenital myasthenic syndrome with acetylcholinesterase deficiency.
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Affiliation(s)
- Séverine M Sigoillot
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France
| | - Francine Bourgeois
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France
| | - Jennifer Karmouch
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France
| | - Jordi Molgó
- Commissariat à l'énergie Atomique et aux Energies Alternatives, Institut de Biologie et Technologies de Saclay, Service d'Ingénierie Moléculaire des Protéines, Gif sur Yvette, France; Institut des Neurosciences Paris-Saclay, UMR 9197, CNRS/Université Paris-Sud, Paris, France; and
| | - Alexandre Dobbertin
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France
| | - Catherine Chevalier
- Institut de Recherche Thérapeutique de l'Université de Nantes, Plateforme Génomique Intégrative, Nantes, France
| | - Rémi Houlgatte
- Institut de Recherche Thérapeutique de l'Université de Nantes, Plateforme Génomique Intégrative, Nantes, France
| | - Jean Léger
- Institut de Recherche Thérapeutique de l'Université de Nantes, Plateforme Génomique Intégrative, Nantes, France
| | - Claire Legay
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France;
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33
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Gandolfi B, Grahn RA, Creighton EK, Williams DC, Dickinson PJ, Sturges BK, Guo LT, Shelton GD, Leegwater PAJ, Longeri M, Malik R, Lyons LA. COLQ variant associated with Devon Rex and Sphynx feline hereditary myopathy. Anim Genet 2015; 46:711-5. [PMID: 26374066 PMCID: PMC4637250 DOI: 10.1111/age.12350] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2015] [Indexed: 01/26/2023]
Abstract
Some Devon Rex and Sphynx cats have a variably progressive myopathy characterized by appendicular and axial muscle weakness, megaesophagus, pharyngeal weakness and fatigability with exercise. Muscle biopsies from affected cats demonstrated variable pathological changes ranging from dystrophic features to minimal abnormalities. Affected cats have exacerbation of weakness following anticholinesterase dosing, a clue that there is an underlying congenital myasthenic syndrome (CMS). A genome-wide association study and whole-genome sequencing suggested a causal variant for this entity was a c.1190G>A variant causing a cysteine to tyrosine substitution (p.Cys397Tyr) within the C-terminal domain of collagen-like tail subunit (single strand of homotrimer) of asymmetric acetylcholinesterase (COLQ). Alpha-dystroglycan expression, which is associated with COLQ anchorage at the motor end-plate, has been shown to be deficient in affected cats. Eighteen affected cats were identified by genotyping, including cats from the original clinical descriptions in 1993 and subsequent publications. Eight Devon Rex and one Sphynx not associated with the study were identified as carriers, suggesting an allele frequency of ~2.0% in Devon Rex. Over 350 tested cats from other breeds did not have the variant. Characteristic clinical features and variant presence in all affected cats suggest a model for COLQ CMS. The association between the COLQ variant and this CMS affords clinicians the opportunity to confirm diagnosis via genetic testing and permits owners and breeders to identify carriers in the population. Moreover, accurate diagnosis increases available therapeutic options for affected cats based on an understanding of the pathophysiology and experience from human CMS associated with COLQ variants.
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Affiliation(s)
- Barbara Gandolfi
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri - Columbia, Columbia, MO, 65211, USA
| | - Robert A Grahn
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California - Davis, Davis, CA, 95616, USA
| | - Erica K Creighton
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri - Columbia, Columbia, MO, 65211, USA
| | - D Colette Williams
- The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California - Davis, Davis, CA, 95616, USA
| | - Peter J Dickinson
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA, 95616, USA
| | - Beverly K Sturges
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA, 95616, USA
| | - Ling T Guo
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA, 95616, USA
| | - G Diane Shelton
- Department of Pathology, University of California - San Diego, La Jolla, CA, 92093, USA
| | - Peter A J Leegwater
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, 3508 TD, Utrecht, The Netherlands
| | - Maria Longeri
- Dipartimento di Scienze Veterinarie e Sanità Pubblica, University of Milan, Milan, Italy
| | - Richard Malik
- Centre for Veterinary Education, University of Sydney, Sydney, NSW, 2006, Australia
| | - Leslie A Lyons
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri - Columbia, Columbia, MO, 65211, USA
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Collagen Q and anti-MuSK autoantibody competitively suppress agrin/LRP4/MuSK signaling. Sci Rep 2015; 5:13928. [PMID: 26355076 PMCID: PMC4564764 DOI: 10.1038/srep13928] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 08/11/2015] [Indexed: 11/25/2022] Open
Abstract
MuSK antibody-positive myasthenia gravis (MuSK-MG) accounts for 5 to 15% of autoimmune MG. MuSK and LRP4 are coreceptors for agrin in the signaling pathway that causes clustering of acetylcholine receptor (AChR). MuSK also anchors the acetylcholinesterase (AChE)/collagen Q (ColQ) complex to the synaptic basal lamina. We previously reported that anti-MuSK antibodies (MuSK-IgG) block binding of ColQ to MuSK and cause partial endplate AChE deficiency in mice. We here analyzed the physiological significance of binding of ColQ to MuSK and block of this binding by MuSK-IgG. In vitro plate-binding assay showed that MuSK-IgG blocked MuSK-LRP4 interaction in the presence of agrin. Passive transfer of MuSK-IgG to Colq-knockout mice attenuated AChR clustering, indicating that lack of ColQ is not the key event causing defective clustering of AChR in MuSK-MG. In three MuSK-MG patients, the MuSK antibodies recognized the first and fourth immunoglobulin-like domains (Ig1 and Ig4) of MuSK. In two other MuSK-MG patients, they recognized only the Ig4 domain. LRP4 and ColQ also bound to the Ig1 and Ig4 domains of MuSK. Unexpectedly, the AChE/ColQ complex blocked MuSK-LRP4 interaction and suppressed agrin/LRP4/MuSK signaling. Quantitative analysis showed that MuSK-IgG suppressed agrin/LRP4/MuSK signaling to a greater extent than ColQ.
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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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MuSK frizzled-like domain is critical for mammalian neuromuscular junction formation and maintenance. J Neurosci 2015; 35:4926-41. [PMID: 25810523 DOI: 10.1523/jneurosci.3381-14.2015] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The muscle-specific kinase MuSK is one of the key molecules orchestrating neuromuscular junction (NMJ) formation. MuSK interacts with the Wnt morphogens, through its Frizzled-like domain (cysteine-rich domain [CRD]). Dysfunction of MuSK CRD in patients has been recently associated with the onset of myasthenia, common neuromuscular disorders mainly characterized by fatigable muscle weakness. However, the physiological role of Wnt-MuSK interaction in NMJ formation and function remains to be elucidated. Here, we demonstrate that the CRD deletion of MuSK in mice caused profound defects of both muscle prepatterning, the first step of NMJ formation, and synapse differentiation associated with a drastic deficit in AChR clusters and excessive growth of motor axons that bypass AChR clusters. Moreover, adult MuSKΔCRD mice developed signs of congenital myasthenia, including severe NMJs dismantlement, muscle weakness, and fatigability. We also report, for the first time, the beneficial effects of lithium chloride, a reversible inhibitor of the glycogen synthase kinase-3, that rescued NMJ defects in MuSKΔCRD mice and therefore constitutes a novel therapeutic reagent for the treatment of neuromuscular disorders linked to Wnt-MuSK signaling pathway deficiency. Together, our data reveal that MuSK CRD is critical for NMJ formation and plays an unsuspected role in NMJ maintenance in adulthood.
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A critical and previously unsuspected role for doublecortin at the neuromuscular junction in mouse and human. Neuromuscul Disord 2015; 25:461-73. [DOI: 10.1016/j.nmd.2015.01.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 01/28/2015] [Indexed: 11/19/2022]
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Ohno K, Ito M, Kawakami Y, Ohtsuka K. Collagen Q is a key player for developing rational therapy for congenital myasthenia and for dissecting the mechanisms of anti-MuSK myasthenia gravis. J Mol Neurosci 2015; 53:359-61. [PMID: 24234034 DOI: 10.1007/s12031-013-0170-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 10/31/2013] [Indexed: 11/28/2022]
Abstract
Acetylcholinesterase (AChE) at the neuromuscular junction (NMJ) is anchored to the synaptic basal lamina via a triple helical collagen Q (ColQ) in the form of asymmetric AChE (AChE/ColQ). We exploited the proprietary NMJ-targeting signals of ColQ to treat congenital myasthenia and to explore the mechanisms of autoimmune myasthenia gravis (MG). Mutations in COLQ cause congenital endplate AChE deficiency (CEAD). First, a single intravenous administration of adeno-associated virus serotype 8 (AAV8)-COLQ to Colq−/− mice normalized motor functions, synaptic transmission, and partly the NMJ ultrastructure. Additionally, injection of purified recombinant AChE/ColQ protein complex into gluteus maximus accumulated AChE in non-injected forelimbs. Second, MuSK antibody-positive MG accounts for 5-15 % of MG. In vitro overlay of AChE/ColQ to muscle sections of Colq−/− mice, as well as in vitro plate-binding of MuSK to ColQ, revealed thatMuSK-IgG blocks binding of ColQ to MuSK in a dose-dependent manner. Passive transfer of MuSK-IgG to wild-type mice markedly reduced the size and intensity of ColQ signals at NMJs. MuSK-IgG thus interferes with binding of ColQ to MuSK. Elucidation of molecular mechanisms of specific binding of ColQ to NMJ enabled us to ameliorate devastating myasthenic symptoms of Colq−/− mice and also to reveal underlying mechanisms of anti-MuSK-MG.
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Arredondo J, Lara M, Ng F, Gochez DA, Lee DC, Logia SP, Nguyen J, Maselli RA. COOH-terminal collagen Q (COLQ) mutants causing human deficiency of endplate acetylcholinesterase impair the interaction of ColQ with proteins of the basal lamina. Hum Genet 2013; 133:599-616. [PMID: 24281389 DOI: 10.1007/s00439-013-1391-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 11/03/2013] [Indexed: 02/06/2023]
Abstract
Collagen Q (ColQ) is a key multidomain functional protein of the neuromuscular junction (NMJ), crucial for anchoring acetylcholinesterase (AChE) to the basal lamina (BL) and accumulating AChE at the NMJ. The attachment of AChE to the BL is primarily accomplished by the binding of the ColQ collagen domain to the heparan sulfate proteoglycan perlecan and the COOH-terminus to the muscle-specific receptor tyrosine kinase (MuSK), which in turn plays a fundamental role in the development and maintenance of the NMJ. Yet, the precise mechanism by which ColQ anchors AChE at the NMJ remains unknown. We identified five novel mutations at the COOH-terminus of ColQ in seven patients from five families affected with endplate (EP) AChE deficiency. We found that the mutations do not affect the assembly of ColQ with AChE to form asymmetric forms of AChE or impair the interaction of ColQ with perlecan. By contrast, all mutations impair in varied degree the interaction of ColQ with MuSK as well as basement membrane extract (BME) that have no detectable MuSK. Our data confirm that the interaction of ColQ to perlecan and MuSK is crucial for anchoring AChE to the NMJ. In addition, the identified COOH-terminal mutants not only reduce the interaction of ColQ with MuSK, but also diminish the interaction of ColQ with BME. These findings suggest that the impaired attachment of COOH-terminal mutants causing EP AChE deficiency is in part independent of MuSK, and that the COOH-terminus of ColQ may interact with other proteins at the BL.
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Affiliation(s)
- Juan Arredondo
- Department of Neurology, University of California Davis, 1515 Newton Court, Room 510, Davis, CA, 95618, USA,
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41
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Nakata T, Ito M, Azuma Y, Otsuka K, Noguchi Y, Komaki H, Okumura A, Shiraishi K, Masuda A, Natsume J, Kojima S, Ohno K. Mutations in the C-terminal domain of ColQ in endplate acetylcholinesterase deficiency compromise ColQ-MuSK interaction. Hum Mutat 2013; 34:997-1004. [PMID: 23553736 DOI: 10.1002/humu.22325] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Accepted: 03/19/2013] [Indexed: 11/11/2022]
Abstract
Acetylcholinesterase (AChE) at the neuromuscular junction (NMJ) is mostly composed of an asymmetric form in which three tetramers of catalytic AChE subunits are linked to a triple helical collagen Q (ColQ). Mutations in COLQ cause endplate AChE deficiency. We report three patients with endplate AChE deficiency with five recessive COLQ mutations. Sedimentation profiles showed that p.Val322Asp and p.Arg227X, but not p.Cys444Tyr, p.Asp447His, or p.Arg452Cys, inhibit formation of triple helical ColQ. In vitro overlay of mutant ColQ-tailed AChE on muscle sections of Colq(-/-) mice revealed that p.Cys444Tyr, p.Asp447His, and p.Arg452Cys in the C-terminal domain (CTD) abrogate anchoring ColQ-tailed AChE to the NMJ. In vitro plate-binding assay similarly demonstrated that the three mutants inhibit binding of ColQ-tailed AChE to MuSK. We also confirmed the pathogenicity of p.Asp447His by treating Colq(-/-) mice with adeno-associated virus serotype 8 carrying mutant COLQ-p.Asp447His. The treated mice showed no improvement in motor functions and no anchoring of ColQ-tailed AChE at the NMJ. Electroporation of mutant COLQ harboring p.Cys444Tyr, p.Asp447His, and p.Arg452Cys into anterior tibial muscles of Colq(-/-) mice similarly failed to anchor ColQ-tailed AChE at the NMJ. We proved that the missense mutations in ColQ-CTD cause endplate AChE deficiency by compromising ColQ-MuSK interaction at the NMJ.
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Affiliation(s)
- Tomohiko Nakata
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
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Takamori M. Structure of the neuromuscular junction: function and cooperative mechanisms in the synapse. Ann N Y Acad Sci 2013; 1274:14-23. [PMID: 23252893 DOI: 10.1111/j.1749-6632.2012.06784.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
As an overview of the structure of the neuromuscular junction, three items are described focusing on cooperative mechanisms involving the synapse and leading to muscle contraction: (1) presynaptic acetylcholine release regulated by vesicle cycling (exocytosis and endocytosis); the fast-mode of endocytosis requires a large influx of external Ca(2+) and is promoted by the activation of G protein-coupled receptors and receptor tyrosine kinases; (2) postsynaptic acetylcholine receptor clustering mediated by the muscle-specific, Dok7-stimulated tyrosine kinase (MuSK) through two signaling mechanisms: one via agrin-Lrp4-MuSK (Ig1/2 domains) and the second via Wnt-MuSK (Frizzled-like cysteine-rich domain)-adaptor Dishevelled; Wnts/MuSK and Lrp4 direct a retrograde signal to presynaptic differentiation; (3) muscle contractile machinery regulated by Ca(2+) -release and Ca(2+) -influx channels, including the depolarization-activated ryanodine receptor-1 and the receptor- and/or store-operated transient receptor potential canonical. The first mechanism is dysfunctional in Lambert-Eaton myasthenic syndrome, the second in anti-acetylcholine receptor-negative myasthenia gravis (MG), and the third in thymoma-associated MG.
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43
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Zong Y, Jin R. Structural mechanisms of the agrin-LRP4-MuSK signaling pathway in neuromuscular junction differentiation. Cell Mol Life Sci 2012. [PMID: 23178848 DOI: 10.1007/s00018-012-1209-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The neuromuscular junction (NMJ) is the most extensively studied model of neuronal synaptogenesis. Acetylcholine receptor (AChR) clustering on the postsynaptic membrane is a cardinal event in the differentiation of NMJs. AChR clustering and postsynaptic differentiation is orchestrated by sophisticated interactions among three proteins: the neuron-secreted proteoglycan agrin, the co-receptor LRP4, and the muscle-specific receptor tyrosine kinase MuSK. LRP4 and MuSK act as scaffolds for multiple binding partners, resulting in a complex and dynamic network of interacting proteins that is required for AChR clustering. In this review, we discuss the structural basis for NMJ postsynaptic differentiation mediated by the agrin-LRP4-MuSK signaling pathway.
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Affiliation(s)
- Yinong Zong
- Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA, 92037, USA
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Mis K, Matkovic U, Pirkmajer S, Sciancalepore M, Lorenzon P, Mars T, Grubic Z. Acetylcholinesterase and agrin: different functions, similar expression patterns, multiple roles. Chem Biol Interact 2012; 203:297-301. [PMID: 23117006 DOI: 10.1016/j.cbi.2012.10.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 10/16/2012] [Accepted: 10/17/2012] [Indexed: 12/31/2022]
Abstract
Acetylcholinesterase (AChE) and agrin play unique functional roles in the neuromuscular junction (NMJ). AChE is a cholinergic and agrin a synaptogenetic component. In spite of their different functions, they share several common features: their targeting is determined by alternative splicing; unlike most other NMJ components they are expressed in both, muscle and motor neuron and both reside on the synaptic basal lamina of the NMJ. Also, both were reported to play various nonjunctional roles. However, while the origin of basal lamina bound agrin is undoubtedly neural, the neural origin of AChE, which is anchored to the basal lamina with collagenic tail ColQ, is elusive. Hypothesizing that motor neuron proteins targeted to the NMJ basal lamina share common temporal pattern of expression, which is coordinated with the formation of basal lamina, we compared expression of agrin isoforms with the expression of AChE-T and ColQ in the developing rat spinal cord at the stages before and after the formation of NMJ basal lamina. Cellular origin of AChE-T and agrin was determined by in situ hybridization and their quantitative levels by RT PCR. We found parallel increase in expression of the synaptogenetic (agrin 8) isoform of agrin and ColQ after the formation of basal lamina supporting the view that ColQ bound AChE and agrin 8 isoform are destined to the basal lamina. Catalytic AChE-T subunit and agrin isoforms 19 and 0 followed different expression patterns. In accordance with the reports of other authors, our investigations also revealed various alternative functions for AChE and agrin. We have already demonstrated participation of AChE in myoblast apoptosis; here we present the evidence that agrin promotes the maturation of heavy myosin chains and the excitation-contraction coupling. These results show that common features of AChE and agrin extend to their capacity to play multiple roles in muscle development.
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Affiliation(s)
- Katarina Mis
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
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Karmouch J, Dobbertin A, Sigoillot S, Legay C. Developmental consequences of the ColQ/MuSK interactions. Chem Biol Interact 2012; 203:287-91. [PMID: 23089045 DOI: 10.1016/j.cbi.2012.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 10/09/2012] [Accepted: 10/11/2012] [Indexed: 10/27/2022]
Abstract
CollagenQ (ColQ) is a specific collagen that anchors acetylcholinesterase (AChE) in the synaptic basal lamina of the neuromuscular junction (NMJ). Over 30 mutations in the COLQ gene have been identified that are responsible for a congenital myasthenic syndrome with AChE deficiency, highlighting the importance of this collagen in the physiology of the NMJ. The anchoring of AChE at the synapse requires the interaction of ColQ with MuSK (Muscle-Specific Kinase), a tyrosine kinase expressed on the muscle membrane that is necessary for the formation and the maintenance of the NMJ. MuSK forms with its co-receptor LRP4, a member of the Low-density Related Protein family, a receptor complex for agrin and Wnts, representing the core system from which the postsynaptic domain is built, the growth cone attracted and the presynaptic element instructed for some aspects of its differentiation. Therefore, the discovery that ColQ binds to MuSK prompted us to study a possible regulatory function of ColQ during NMJ development. In this review, after a brief survey on ColQ, we summarize our recent data demonstrating that ColQ, in addition to its anchoring role, exerts signaling functions and controls some aspects of postsynaptic differentiation such as the clustering of acetylcholine receptors. Our results also strengthen the hypothesis that the defects observed in synaptic congenital myasthenic syndromes might be linked, at least in part, to alterations of ColQ signaling functions and not only to AChE deficiency. Finally, we discuss future research directions to understand how ColQ may modulate the action of the other ligands of the MuSK/LRP4 complex and cooperate with them to coordinate the different steps of NMJ formation and maintenance.
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Affiliation(s)
- Jennifer Karmouch
- CESEM, CNRS UMR 8194, University of Paris Descartes, 45 rue des Saints-Pères, 75006 Paris Cedex, France
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Singhal N, Martin PT. Role of extracellular matrix proteins and their receptors in the development of the vertebrate neuromuscular junction. Dev Neurobiol 2012; 71:982-1005. [PMID: 21766463 DOI: 10.1002/dneu.20953] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The vertebrate neuromuscular junction (NMJ) remains the best-studied model for understanding the mechanisms involved in synaptogenesis, due to its relatively large size, its simplicity of patterning, and its unparalleled experimental accessibility. During neuromuscular development, each skeletal myofiber secretes and deposits around its extracellular surface an assemblage of extracellular matrix (ECM) proteins that ultimately form a basal lamina. This is also the case at the NMJ, where the motor nerve contributes additional factors. Before most of the current molecular components were known, it was clear that the synaptic ECM of adult skeletal muscles was unique in composition and contained factors sufficient to induce the differentiation of both pre- and postsynaptic membranes. Biochemical, genetic, and microscopy studies have confirmed that agrin, laminin (221, 421, and 521), collagen IV (α3-α6), collagen XIII, perlecan, and the ColQ-bound form of acetylcholinesterase are all synaptic ECM proteins with important roles in neuromuscular development. The roles of their many potential receptors and/or binding proteins have been more difficult to assess at the genetic level due to the complexity of membrane interactions with these large proteins, but roles for MuSK-LRP4 in agrin signaling and for integrins, dystroglycan, and voltage-gated calcium channels in laminin-dependent phenotypes have been identified. Synaptic ECM proteins and their receptors are involved in almost all aspects of synaptic development, including synaptic initiation, topography, ultrastructure, maturation, stability, and transmission.
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Affiliation(s)
- Neha Singhal
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, Department of Pediatrics, Ohio State University College of Medicine, Columbus, Ohio 43205, USA
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Ma K, Huang Z, Ma J, Shao L, Wang H, Wang Y. Perlecan and synaptophysin changes in denervated skeletal muscle. Neural Regen Res 2012; 7:1293-8. [PMID: 25657658 PMCID: PMC4308798 DOI: 10.3969/j.issn.1673-5374.2012.17.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 04/23/2012] [Indexed: 11/18/2022] Open
Abstract
The present study observed sciatic nerve and gastrocnemius muscle changes in denervated rats using morphology methods, and assessed expression of perlecan, an extracellular matrix component, which is located at the skeletal muscle cell surface as acetylcholine esterase, as well as synaptophysin, a synaptic marker. Results showed degeneration and inflammation following transection of the sciatic nerve. In addition, the sciatic nerve-dominated skeletal muscle degenerated with mild inflammation, indicating that skeletal muscle atrophy primarily contributed to denervation-induced nutritional disturbances. With prolonged injury time (1-4 weeks post-injury), perlecan expression gradually decreased and reached the lowest level at 4 weeks, but synaptophysin expression remained unchanged after denervation. Results suggested that perlecan expression was more sensitive to denervation and reflected regional extracellular matrix changes following denervation.
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Affiliation(s)
- Kai Ma
- Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Medical College of Zhejiang University, Hangzhou 310006, Zhejiang Province, China ; Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Wenzhou Medical College, Wenzhou 325027, Zhejiang Province, China
| | - Zhifeng Huang
- School of Pharmacy, Wenzhou Medical College, Wenzhou 325000, Zhejiang Province, China
| | - Jianfeng Ma
- Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Wenzhou Medical College, Wenzhou 325027, Zhejiang Province, China
| | - Longquan Shao
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, Guangdong Province, China
| | - Huiming Wang
- Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Medical College of Zhejiang University, Hangzhou 310006, Zhejiang Province, China
| | - Yanliang Wang
- Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Wenzhou Medical College, Wenzhou 325027, Zhejiang Province, China
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48
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Molecular mechanisms underlying maturation and maintenance of the vertebrate neuromuscular junction. Trends Neurosci 2012; 35:441-53. [PMID: 22633140 DOI: 10.1016/j.tins.2012.04.005] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 04/09/2012] [Accepted: 04/15/2012] [Indexed: 01/22/2023]
Abstract
The vertebrate neuromuscular junction (NMJ), a peripheral synapse formed between motoneuron and skeletal muscle, is characterized by a protracted postnatal period of maturation and life-long maintenance. In neuromuscular disorders such as congenital myasthenic syndromes (CMSs), disruptions of NMJ maturation and/or maintenance are frequently observed. In particular, defective neuromuscular transmission associated with structural and molecular abnormalities at the pre- and postsynaptic membranes, as well as at the synaptic cleft, has been reported in these patients. Here, we review recent advances in the understanding of molecular and cellular events that mediate NMJ maturation and maintenance. The underlying regulatory mechanisms, including key molecular regulators at the presynaptic nerve terminal, synaptic cleft, and postsynaptic muscle membrane, are discussed.
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Long-term follow-up of patients with congenital myasthenic syndrome caused by COLQ mutations. Neuromuscul Disord 2012; 22:318-24. [DOI: 10.1016/j.nmd.2011.09.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 08/24/2011] [Accepted: 09/02/2011] [Indexed: 11/18/2022]
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Wnt4 participates in the formation of vertebrate neuromuscular junction. PLoS One 2012; 7:e29976. [PMID: 22253844 PMCID: PMC3257248 DOI: 10.1371/journal.pone.0029976] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 12/07/2011] [Indexed: 01/27/2023] Open
Abstract
Neuromuscular junction (NMJ) formation requires the highly coordinated communication of several reciprocal signaling processes between motoneurons and their muscle targets. Identification of the early, spatially restricted cues in target recognition at the NMJ is still poorly documented, especially in mammals. Wnt signaling is one of the key pathways regulating synaptic connectivity. Here, we report that Wnt4 contributes to the formation of vertebrate NMJ in vivo. Results from a microarray screen and quantitative RT-PCR demonstrate that Wnt4 expression is regulated during muscle cell differentiation in vitro and muscle development in vivo, being highly expressed when the first synaptic contacts are formed and subsequently downregulated. Analysis of the mouse Wnt4−/− NMJ phenotype reveals profound innervation defects including motor axons overgrowing and bypassing AChR aggregates with 30% of AChR clusters being unapposed by nerve terminals. In addition, loss of Wnt4 function results in a 35% decrease of the number of prepatterned AChR clusters while Wnt4 overexpression in cultured myotubes increases the number of AChR clusters demonstrating that Wnt4 directly affects postsynaptic differentiation. In contrast, muscle structure and the localization of several synaptic proteins including acetylcholinesterase, MuSK and rapsyn are not perturbed in the Wnt4 mutant. Finally, we identify MuSK as a Wnt4 receptor. Wnt4 not only interacts with MuSK ectodomain but also mediates MuSK activation. Taken together our data reveal a new role for Wnt4 in mammalian NMJ formation that could be mediated by MuSK, a key receptor in synaptogenesis.
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