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Yıldırım M, Yarenci GB, Genç MB, Uçar Çİ, Bayav S, Tekin MN, Bektaş Ö, Teber S. VAMP1-Related Congenital Myasthenic Syndrome: A Case Report and Literature Review. Neuropediatrics 2024; 55:200-204. [PMID: 38531369 DOI: 10.1055/s-0044-1782675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
Congenital myasthenic syndrome-25 (CMS-25) is an autosomal recessive neuromuscular disorder caused by a homozygous mutation in VAMP1 gene. To date, only eight types of allelic variants in VAMP1 gene have been reported in 12 cases of CMS-25. Here, we report on an 8-year-old boy with motor developmental delay, axial hypotonia, myopathic face, muscle weakness, strabismus, ptosis, pectus carinatum, kyphoscoliosis, joint contractures, joint laxity, seizures, and recurrent nephrolithiasis. He also had feeding difficulties and recurrent aspiration pneumonia. Brain magnetic resonance imaging at 20 months of age showed left focal cerebellar hypoplasia. Genetic analysis revealed a homozygous missense variant of c.202C > T (p.Arg68Ter) in the VAMP1 gene. Treatment with oral pyridostigmine was started, which resulted in mild improvement in muscle strength. Salbutamol syrup was added a few months later, but no significant improvement was observed. This case report presents novel findings such as focal cerebellar hypoplasia and nephrolithiasis in VAMP1-related CMS-25. Consequently, this case report extends the clinical spectrum. Further studies are needed to expand the genotype-phenotype correlations in VAMP1-related CMS-25.
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Affiliation(s)
- Miraç Yıldırım
- Department of Pediatric Neurology, Ankara University Faculty of Medicine, Ankara, Turkey
| | | | | | - Çiğdem İlter Uçar
- Department of Pediatric Neurology, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Secahattin Bayav
- Department of Pediatric Pulmonology, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Merve Nur Tekin
- Department of Pediatric Pulmonology, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Ömer Bektaş
- Department of Pediatric Neurology, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Serap Teber
- Department of Pediatric Neurology, Ankara University Faculty of Medicine, Ankara, Turkey
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2
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Kádková A, Murach J, Østergaard M, Malsam A, Malsam J, Lolicato F, Nickel W, Söllner TH, Sørensen JB. SNAP25 disease mutations change the energy landscape for synaptic exocytosis due to aberrant SNARE interactions. eLife 2024; 12:RP88619. [PMID: 38411501 PMCID: PMC10911398 DOI: 10.7554/elife.88619] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024] Open
Abstract
SNAP25 is one of three neuronal SNAREs driving synaptic vesicle exocytosis. We studied three mutations in SNAP25 that cause epileptic encephalopathy: V48F, and D166Y in the synaptotagmin-1 (Syt1)-binding interface, and I67N, which destabilizes the SNARE complex. All three mutations reduced Syt1-dependent vesicle docking to SNARE-carrying liposomes and Ca2+-stimulated membrane fusion in vitro and when expressed in mouse hippocampal neurons. The V48F and D166Y mutants (with potency D166Y > V48F) led to reduced readily releasable pool (RRP) size, due to increased spontaneous (miniature Excitatory Postsynaptic Current, mEPSC) release and decreased priming rates. These mutations lowered the energy barrier for fusion and increased the release probability, which are gain-of-function features not found in Syt1 knockout (KO) neurons; normalized mEPSC release rates were higher (potency D166Y > V48F) than in the Syt1 KO. These mutations (potency D166Y > V48F) increased spontaneous association to partner SNAREs, resulting in unregulated membrane fusion. In contrast, the I67N mutant decreased mEPSC frequency and evoked EPSC amplitudes due to an increase in the height of the energy barrier for fusion, whereas the RRP size was unaffected. This could be partly compensated by positive charges lowering the energy barrier. Overall, pathogenic mutations in SNAP25 cause complex changes in the energy landscape for priming and fusion.
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Affiliation(s)
- Anna Kádková
- Department of Neuroscience, University of CopenhagenCopenhagenDenmark
| | | | - Maiken Østergaard
- Department of Neuroscience, University of CopenhagenCopenhagenDenmark
| | - Andrea Malsam
- Heidelberg University Biochemistry CenterHeidelbergDenmark
| | - Jörg Malsam
- Heidelberg University Biochemistry CenterHeidelbergDenmark
| | - Fabio Lolicato
- Heidelberg University Biochemistry CenterHeidelbergDenmark
- Department of Physics, University of HelsinkiHelsinkiFinland
| | - Walter Nickel
- Heidelberg University Biochemistry CenterHeidelbergDenmark
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3
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Masek M, Bachmann-Gagescu R. Control of protein and lipid composition of photoreceptor outer segments-Implications for retinal disease. Curr Top Dev Biol 2023; 155:165-225. [PMID: 38043951 DOI: 10.1016/bs.ctdb.2023.09.001] [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] [Indexed: 12/05/2023]
Abstract
Vision is arguably our most important sense, and its loss brings substantial limitations to daily life for affected individuals. Light is perceived in retinal photoreceptors (PRs), which are highly specialized neurons subdivided into several compartments with distinct functions. The outer segments (OSs) of photoreceptors represent highly specialized primary ciliary compartments hosting the phototransduction cascade, which transforms incoming light into a neuronal signal. Retinal disease can result from various pathomechanisms originating in distinct subcompartments of the PR cell, or in the retinal pigment epithelium which supports the PRs. Dysfunction of primary cilia causes human disorders known as "ciliopathies", in which retinal disease is a common feature. This chapter focuses on PR OSs, discussing the mechanisms controlling their complex structure and composition. A sequence of tightly regulated sorting and trafficking events, both upstream of and within this ciliary compartment, ensures the establishment and maintenance of the adequate proteome and lipidome required for signaling in response to light. We discuss in particular our current understanding of the role of ciliopathy proteins involved in multi-protein complexes at the ciliary transition zone (CC2D2A) or BBSome (BBS1) and how their dysfunction causes retinal disease. While the loss of CC2D2A prevents the fusion of vesicles and delivery of the photopigment rhodopsin to the ciliary base, leading to early OS ultrastructural defects, BBS1 deficiency results in precocious accumulation of cholesterol in mutant OSs and decreased visual function preceding morphological changes. These distinct pathomechanisms underscore the central role of ciliary proteins involved in multiple processes controlling OS protein and lipid composition.
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Affiliation(s)
- Markus Masek
- Institute of Medical Genetics, University of Zurich, Zurich, Switzerland; Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Ruxandra Bachmann-Gagescu
- Institute of Medical Genetics, University of Zurich, Zurich, Switzerland; Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland; University Research Priority Program AdaBD, University of Zurich, Zurich, Switzerland.
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4
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Uzay B, Kavalali ET. Genetic disorders of neurotransmitter release machinery. Front Synaptic Neurosci 2023; 15:1148957. [PMID: 37066095 PMCID: PMC10102358 DOI: 10.3389/fnsyn.2023.1148957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 03/10/2023] [Indexed: 04/03/2023] Open
Abstract
Synaptic neurotransmitter release is an evolutionarily conserved process that mediates rapid information transfer between neurons as well as several peripheral tissues. Release of neurotransmitters are ensured by successive events such as synaptic vesicle docking and priming that prepare synaptic vesicles for rapid fusion. These events are orchestrated by interaction of different presynaptic proteins and are regulated by presynaptic calcium. Recent studies have identified various mutations in different components of neurotransmitter release machinery resulting in aberrant neurotransmitter release, which underlie a wide spectrum of psychiatric and neurological symptoms. Here, we review how these genetic alterations in different components of the core neurotransmitter release machinery affect the information transfer between neurons and how aberrant synaptic release affects nervous system function.
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Affiliation(s)
- Burak Uzay
- Vanderbilt Brain Institute, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Ege T. Kavalali
- Vanderbilt Brain Institute, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
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5
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Ohno K, Ohkawara B, Shen XM, Selcen D, Engel AG. Clinical and Pathologic Features of Congenital Myasthenic Syndromes Caused by 35 Genes-A Comprehensive Review. Int J Mol Sci 2023; 24:ijms24043730. [PMID: 36835142 PMCID: PMC9961056 DOI: 10.3390/ijms24043730] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/09/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders characterized by impaired neuromuscular signal transmission due to germline pathogenic variants in genes expressed at the neuromuscular junction (NMJ). A total of 35 genes have been reported in CMS (AGRN, ALG14, ALG2, CHAT, CHD8, CHRNA1, CHRNB1, CHRND, CHRNE, CHRNG, COL13A1, COLQ, DOK7, DPAGT1, GFPT1, GMPPB, LAMA5, LAMB2, LRP4, MUSK, MYO9A, PLEC, PREPL, PURA, RAPSN, RPH3A, SCN4A, SLC18A3, SLC25A1, SLC5A7, SNAP25, SYT2, TOR1AIP1, UNC13A, VAMP1). The 35 genes can be classified into 14 groups according to the pathomechanical, clinical, and therapeutic features of CMS patients. Measurement of compound muscle action potentials elicited by repetitive nerve stimulation is required to diagnose CMS. Clinical and electrophysiological features are not sufficient to identify a defective molecule, and genetic studies are always required for accurate diagnosis. From a pharmacological point of view, cholinesterase inhibitors are effective in most groups of CMS, but are contraindicated in some groups of CMS. Similarly, ephedrine, salbutamol (albuterol), amifampridine are effective in most but not all groups of CMS. This review extensively covers pathomechanical and clinical features of CMS by citing 442 relevant articles.
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Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Correspondence: (K.O.); (A.G.E.)
| | - Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Xin-Ming Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Duygu Selcen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Andrew G. Engel
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
- Correspondence: (K.O.); (A.G.E.)
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6
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Reynolds HM, Wen T, Farrell A, Mao R, Moore B, Boyden SE, Bayrak-Toydemir P, Nicholas TJ, Rynearson S, Holt C, Miller C, Noble K, Bentley D, Palmquist R, Ostrander B, Manberg S, Bonkowsky JL, Shayota BJ, Jenkins SM. Rapid genome sequencing identifies a novel de novo SNAP25 variant for neonatal congenital myasthenic syndrome. Cold Spring Harb Mol Case Stud 2022; 8:a006242. [PMID: 36379720 PMCID: PMC9808558 DOI: 10.1101/mcs.a006242] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022] Open
Abstract
Congenital myasthenic syndrome (CMS) is a group of 32 disorders involving genetic dysfunction at the neuromuscular junction resulting in skeletal muscle weakness that worsens with physical activity. Precise diagnosis and molecular subtype identification are critical for treatment as medication for one subtype may exacerbate disease in another (Engel et al., Lancet Neurol 14: 420 [2015]; Finsterer, Orphanet J Rare Dis 14: 57 [2019]; Prior and Ghosh, J Child Neurol 36: 610 [2021]). The SNAP25-related CMS subtype (congenital myasthenic syndrome 18, CMS18; MIM #616330) is a rare disorder characterized by muscle fatigability, delayed psychomotor development, and ataxia. Herein, we performed rapid whole-genome sequencing (rWGS) on a critically ill newborn leading to the discovery of an unreported pathogenic de novo SNAP25 c.529C > T; p.Gln177Ter variant. In this report, we present a novel case of CMS18 with complex neonatal consequence. This discovery offers unique insight into the extent of phenotypic severity in CMS18, expands the reported SNAP25 variant phenotype, and paves a foundation for personalized management for CMS18.
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Affiliation(s)
- Hayley M Reynolds
- University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Ting Wen
- University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
- ARUP Laboratories, Salt Lake City, Utah 84108, USA
| | - Andrew Farrell
- Department of Human Genetics, Utah Center for Genetic Discovery, Salt Lake City, Utah 84112, USA
| | - Rong Mao
- University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
- ARUP Laboratories, Salt Lake City, Utah 84108, USA
| | - Barry Moore
- Department of Human Genetics, Utah Center for Genetic Discovery, Salt Lake City, Utah 84112, USA
| | - Steven E Boyden
- Department of Human Genetics, Utah Center for Genetic Discovery, Salt Lake City, Utah 84112, USA
| | - Pinar Bayrak-Toydemir
- University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
- ARUP Laboratories, Salt Lake City, Utah 84108, USA
| | - Thomas J Nicholas
- Department of Human Genetics, Utah Center for Genetic Discovery, Salt Lake City, Utah 84112, USA
| | - Shawn Rynearson
- Department of Human Genetics, Utah Center for Genetic Discovery, Salt Lake City, Utah 84112, USA
| | - Carson Holt
- Department of Human Genetics, Utah Center for Genetic Discovery, Salt Lake City, Utah 84112, USA
| | | | | | - Dawn Bentley
- Division of Neonatology, Department of Pediatrics University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Rachel Palmquist
- Division of Pediatric Neurology, Department of Pediatrics University of Utah School of Medicine, Salt Lake City, Utah 84113, USA
| | - Betsy Ostrander
- Division of Pediatric Neurology, Department of Pediatrics University of Utah School of Medicine, Salt Lake City, Utah 84113, USA
| | - Stephanie Manberg
- Division of Pediatric Neurology, Department of Pediatrics University of Utah School of Medicine, Salt Lake City, Utah 84113, USA
| | - Joshua L Bonkowsky
- Division of Pediatric Neurology, Department of Pediatrics University of Utah School of Medicine, Salt Lake City, Utah 84113, USA
- Center for Personalized Medicine, Primary Children's Hospital, Salt Lake City, Utah 84108, USA
| | - Brian J Shayota
- Division of Medical Genetics, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Sabrina Malone Jenkins
- Division of Neonatology, Department of Pediatrics University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
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7
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Michetti C, Falace A, Benfenati F, Fassio A. Synaptic genes and neurodevelopmental disorders: From molecular mechanisms to developmental strategies of behavioral testing. Neurobiol Dis 2022; 173:105856. [PMID: 36070836 DOI: 10.1016/j.nbd.2022.105856] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 10/14/2022] Open
Abstract
Synaptopathies are a class of neurodevelopmental disorders caused by modification in genes coding for synaptic proteins. These proteins oversee the process of neurotransmission, mainly controlling the fusion and recycling of synaptic vesicles at the presynaptic terminal, the expression and localization of receptors at the postsynapse and the coupling between the pre- and the postsynaptic compartments. Murine models, with homozygous or heterozygous deletion for several synaptic genes or knock-in for specific pathogenic mutations, have been developed. They have proved to be extremely informative for understanding synaptic physiology, as well as for clarifying the patho-mechanisms leading to developmental delay, epilepsy and motor, cognitive and social impairments that are the most common clinical manifestations of neurodevelopmental disorders. However, the onset of these disorders emerges during infancy and adolescence while the behavioral phenotyping is often conducted in adult mice, missing important information about the impact of synaptic development and maturation on the manifestation of the behavioral phenotype. Here, we review the main achievements obtained by behavioral testing in murine models of synaptopathies and propose a battery of behavioral tests to improve classification, diagnosis and efficacy of potential therapeutic treatments. Our aim is to underlie the importance of studying behavioral development and better focusing on disease onset and phenotypes.
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Affiliation(s)
- Caterina Michetti
- Department of Experimental Medicine, University of Genoa, Genoa, Italy; Center for Synaptic Neuroscience, Istituto Italiano di Tecnologia, Genoa, Italy.
| | - Antonio Falace
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy
| | - Fabio Benfenati
- Center for Synaptic Neuroscience, Istituto Italiano di Tecnologia, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Anna Fassio
- Department of Experimental Medicine, University of Genoa, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, Genoa, Italy.
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8
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Zhang Y, Ma L, Bao H. Energetics, kinetics, and pathways of SNARE assembly in membrane fusion. Crit Rev Biochem Mol Biol 2022; 57:443-460. [PMID: 36151854 PMCID: PMC9588726 DOI: 10.1080/10409238.2022.2121804] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Fusion of transmitter-containing vesicles with plasma membranes at the synaptic and neuromuscular junctions mediates neurotransmission and muscle contractions, respectively, thereby underlying all thoughts and actions. The fusion process is driven by the coupled folding and assembly of three synaptic SNARE proteins--syntaxin-1 and SNAP-25 on the target plasma membrane (t-SNAREs) and VAMP2 on the vesicular membrane (v-SNARE) into a four-helix bundle. Their assembly is chaperoned by Munc18-1 and many other proteins to achieve the speed and accuracy required for neurotransmission. However, the physiological pathway of SNARE assembly and its coupling to membrane fusion remains unclear. Here, we review recent progress in understanding SNARE assembly and membrane fusion, with a focus on results obtained by single-molecule manipulation approaches and electric recordings of single fusion pores. We describe two pathways of synaptic SNARE assembly, their associated intermediates, energetics, and kinetics. Assembly of the three SNAREs in vitro begins with the formation of a t-SNARE binary complex, on which VAMP2 folds in a stepwise zipper-like fashion. Munc18-1 significantly alters the SNARE assembly pathway: syntaxin-1 and VAMP2 first bind on the surface of Munc18-1 to form a template complex, with which SNAP-25 associates to conclude SNARE assembly and displace Munc18-1. During membrane fusion, multiple trans-SNARE complexes cooperate to open a dynamic fusion pore in a manner dependent upon their copy number and zippering states. Together, these results demonstrate that stepwise and cooperative SNARE assembly drive stagewise membrane fusion.
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Affiliation(s)
- Yongli Zhang
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA;,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA;,Conatct: and
| | - Lu Ma
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA;,Present address: Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Huan Bao
- Department of Molecular Medicine, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida, 33458,Conatct: and
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9
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Lange LM, Gonzalez-Latapi P, Rajalingam R, Tijssen MAJ, Ebrahimi-Fakhari D, Gabbert C, Ganos C, Ghosh R, Kumar KR, Lang AE, Rossi M, van der Veen S, van de Warrenburg B, Warner T, Lohmann K, Klein C, Marras C. Nomenclature of Genetic Movement Disorders: Recommendations of the International Parkinson and Movement Disorder Society Task Force - An Update. Mov Disord 2022; 37:905-935. [PMID: 35481685 DOI: 10.1002/mds.28982] [Citation(s) in RCA: 49] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 01/28/2022] [Accepted: 02/14/2022] [Indexed: 12/13/2022] Open
Abstract
In 2016, the Movement Disorder Society Task Force for the Nomenclature of Genetic Movement Disorders presented a new system for naming genetically determined movement disorders and provided a criterion-based list of confirmed monogenic movement disorders. Since then, a substantial number of novel disease-causing genes have been described, which warrant classification using this system. In addition, with this update, we further refined the system and propose dissolving the imaging-based categories of Primary Familial Brain Calcification and Neurodegeneration with Brain Iron Accumulation and reclassifying these genetic conditions according to their predominant phenotype. We also introduce the novel category of Mixed Movement Disorders (MxMD), which includes conditions linked to multiple equally prominent movement disorder phenotypes. In this article, we present updated lists of newly confirmed monogenic causes of movement disorders. We found a total of 89 different newly identified genes that warrant a prefix based on our criteria; 6 genes for parkinsonism, 21 for dystonia, 38 for dominant and recessive ataxia, 5 for chorea, 7 for myoclonus, 13 for spastic paraplegia, 3 for paroxysmal movement disorders, and 6 for mixed movement disorder phenotypes; 10 genes were linked to combined phenotypes and have been assigned two new prefixes. The updated lists represent a resource for clinicians and researchers alike and they have also been published on the website of the Task Force for the Nomenclature of Genetic Movement Disorders on the homepage of the International Parkinson and Movement Disorder Society (https://www.movementdisorders.org/MDS/About/Committees--Other-Groups/MDS-Task-Forces/Task-Force-on-Nomenclature-in-Movement-Disorders.htm). © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society.
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Affiliation(s)
- Lara M Lange
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Paulina Gonzalez-Latapi
- The Edmond J. Safra Program in Parkinson's Disease and The Morton and Gloria Shulman Movement Disorder Clinic, Toronto Western Hospital, University of Toronto, Toronto, Canada.,Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Rajasumi Rajalingam
- The Edmond J. Safra Program in Parkinson's Disease and The Morton and Gloria Shulman Movement Disorder Clinic, Toronto Western Hospital, University of Toronto, Toronto, Canada
| | - Marina A J Tijssen
- UMCG Expertise Centre Movement Disorders, Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Darius Ebrahimi-Fakhari
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,The Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Carolin Gabbert
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Christos Ganos
- Department of Neurology, Charité University Hospital Berlin, Berlin, Germany
| | - Rhia Ghosh
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Kishore R Kumar
- Molecular Medicine Laboratory and Department of Neurology, Concord Repatriation General Hospital, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia.,Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Anthony E Lang
- The Edmond J. Safra Program in Parkinson's Disease and The Morton and Gloria Shulman Movement Disorder Clinic, Toronto Western Hospital, University of Toronto, Toronto, Canada
| | - Malco Rossi
- Movement Disorders Section, Neuroscience Department, Raul Carrea Institute for Neurological Research (FLENI), Buenos Aires, Argentina
| | - Sterre van der Veen
- UMCG Expertise Centre Movement Disorders, Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Bart van de Warrenburg
- Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Center of Expertise for Parkinson and Movement Disorders, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Tom Warner
- Department of Clinical & Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Katja Lohmann
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Christine Klein
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Connie Marras
- The Edmond J. Safra Program in Parkinson's Disease and The Morton and Gloria Shulman Movement Disorder Clinic, Toronto Western Hospital, University of Toronto, Toronto, Canada
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10
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Spoto G, Valentini G, Saia MC, Butera A, Amore G, Salpietro V, Nicotera AG, Di Rosa G. Synaptopathies in Developmental and Epileptic Encephalopathies: A Focus on Pre-synaptic Dysfunction. Front Neurol 2022; 13:826211. [PMID: 35350397 PMCID: PMC8957959 DOI: 10.3389/fneur.2022.826211] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/24/2022] [Indexed: 12/25/2022] Open
Abstract
The proper connection between the pre- and post-synaptic nervous cells depends on any element constituting the synapse: the pre- and post-synaptic membranes, the synaptic cleft, and the surrounding glial cells and extracellular matrix. An alteration of the mechanisms regulating the physiological synergy among these synaptic components is defined as “synaptopathy.” Mutations in the genes encoding for proteins involved in neuronal transmission are associated with several neuropsychiatric disorders, but only some of them are associated with Developmental and Epileptic Encephalopathies (DEEs). These conditions include a heterogeneous group of epilepsy syndromes associated with cognitive disturbances/intellectual disability, autistic features, and movement disorders. This review aims to elucidate the pathogenesis of these conditions, focusing on mechanisms affecting the neuronal pre-synaptic terminal and its role in the onset of DEEs, including potential therapeutic approaches.
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Affiliation(s)
- Giulia Spoto
- Unit of Child Neurology and Psychiatry, Department of Human Pathology of the Adult and Developmental Age “Gaetano Barresi”, University of Messina, Messina, Italy
| | - Giulia Valentini
- Unit of Child Neurology and Psychiatry, Department of Human Pathology of the Adult and Developmental Age “Gaetano Barresi”, University of Messina, Messina, Italy
| | - Maria Concetta Saia
- Unit of Child Neurology and Psychiatry, Department of Human Pathology of the Adult and Developmental Age “Gaetano Barresi”, University of Messina, Messina, Italy
| | - Ambra Butera
- Unit of Child Neurology and Psychiatry, Department of Human Pathology of the Adult and Developmental Age “Gaetano Barresi”, University of Messina, Messina, Italy
| | - Greta Amore
- Unit of Child Neurology and Psychiatry, Department of Human Pathology of the Adult and Developmental Age “Gaetano Barresi”, University of Messina, Messina, Italy
| | - Vincenzo Salpietro
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, United Kingdom
- Pediatric Neurology and Muscular Diseases Unit, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Giannina Gaslini, Genoa, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
- *Correspondence: Vincenzo Salpietro
| | - Antonio Gennaro Nicotera
- Unit of Child Neurology and Psychiatry, Department of Human Pathology of the Adult and Developmental Age “Gaetano Barresi”, University of Messina, Messina, Italy
| | - Gabriella Di Rosa
- Unit of Child Neurology and Psychiatry, Department of Human Pathology of the Adult and Developmental Age “Gaetano Barresi”, University of Messina, Messina, Italy
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11
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Chen G, Xiong S, Zou G, Wu F, Qu X, Alawbathani S, Sun L. A 6.3 Mb maternally derived microduplication of 20p13p12.2 in a fetus with Brachydactyly type D and related literature review. Mol Cytogenet 2022; 15:6. [PMID: 35227291 PMCID: PMC8887085 DOI: 10.1186/s13039-022-00584-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Accepted: 01/26/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
With the introduction of genetic tests such as chromosomal microarray analysis (CMA) and exome sequencing (ES) into fetal medical practices, genotype–phenotype correlations in intrauterine-onset disorders have substantially improved. The BMP2 gene, located on the long arm of chromosome 20 plays a role in bone and cartilage development and is associated with Brachydactyly type A2, an autosomal dominant disease characterized by malformations of the middle phalanx of the index finger and abnormalities of the second toe. However, the BMP2 gene has so far never been reported as a candidate gene for Brachydactyly type D (BDD) affecting only the thumbs.
Methods and
results
Here, we report one family possessing a maternally inherited 6.3 Mb microduplication of 20p13p12.2 including the BMP2 gene with discordant phenotypes between the mother and the fetus. The mother was affected with BDD alongside mild facial dysmorphism and learning difficulties, while the female fetus showed BDD, severe symmetric intrauterine growth restriction combined with oligohydramnios. The CMA and Trio ES tests were implemented. Trio ES ruled out other possible monogenic causes for the family. After reviewing cases and literature with duplications within this genomic region, we found that they are extremely rare and most of the cited cases were too small for comparison. The disturbance of the BMP2 gene could explain BDD, but the other clinical presentations in the mother and fetus are not yet fully understood.
Conclusion
This study provides important evidence for the current understanding of genotype–phenotype association of this 6.3 Mb size duplication in the 20p13p12.2 region. This duplication is a unique CNV occurring so far only in this family. Further cases and research are needed to understand the discordance in the phenotypes between the mother and fetus and establish the relationship between BMP2 gene and BDD.
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12
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Banerjee A, Senguttuvan G, Reddy C, Saini AG. Fluctuating Weakness in an 18-Month-Boy: Congenital Myasthenia. JOURNAL OF PEDIATRIC NEUROLOGY 2021. [DOI: 10.1055/s-0040-1718771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
AbstractIn this article, we reported a case of an 18-month-old male child patient who presented with motor predominant delay in attaining developmental milestones and early onset fatiguable weakness with ptosis and ophthalmoparesis. This ptosis and ophthalmoparesis typically worsened with progression of the day. Examination showed proximal weakness with preserved muscle stretch reflexes. Electrophysiology showed characteristic decrement on repetitive nerve stimulation test that localized to disorders of the neuromuscular junction. Next-generation sequencing showed a pathogenic variant of CHRNE that was responsible for congenital myasthenic syndrome. Such variants show increased improvement with salbutamol in addition to anticholinesterase inhibitors. Hence, the patient was started on pyridostigmine, and the plan was to add on salbutamol on follow-up if optimal improvement does not occur.
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Affiliation(s)
- Arundhati Banerjee
- Department of Pediatrics, Pediatric Neurology Unit, Advanced Pediatrics Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Gananamani Senguttuvan
- Department of Pediatrics, Pediatric Neurology Unit, Advanced Pediatrics Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Chaitanya Reddy
- Department of Pediatrics, Pediatric Neurology Unit, Advanced Pediatrics Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Arushi Gahlot Saini
- Department of Pediatrics, Pediatric Neurology Unit, Advanced Pediatrics Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India
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13
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Estephan EP, Zambon AA, Thompson R, Polavarapu K, Jomaa D, Töpf A, Helito PVP, Heise CO, Moreno CAM, Silva AMS, Kouyoumdjian JA, Morita MDP, Reed UC, Lochmüller H, Zanoteli E. Congenital myasthenic syndrome: Correlation between clinical features and molecular diagnosis. Eur J Neurol 2021; 29:833-842. [PMID: 34749429 DOI: 10.1111/ene.15173] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/01/2021] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To present phenotype features of a large cohort of congenital myasthenic syndromes (CMS) and correlate them with their molecular diagnosis. METHODS Suspected CMS patients were divided into three groups: group A (limb, bulbar or axial weakness, with or without ocular impairment, and all the following: clinical fatigability, electrophysiology compatible with neuromuscular junction involvement and anticholinesterase agents response), group B (limb, bulbar or axial weakness, with or without ocular impairment, and at least one of additional characteristics noted in group A) and group C (pure ocular syndrome). Individual clinical findings and the clinical groups were compared between the group with a confirmed molecular diagnosis of CMS and the group without molecular diagnosis or with a non-CMS molecular diagnosis. RESULTS Seventy-nine patients (68 families) were included in the cohort: 48 in group A, 23 in group B and 8 in group C. Fifty-one were considered confirmed CMS (30 CHRNE, 5 RAPSN, 4 COL13A1, 3 DOK7, 3 COLQ, 2 GFPT1, 1 CHAT, 1 SCN4A, 1 GMPPB, 1 CHRNA1), 7 probable CMS, 5 non-CMS and 16 unsolved. The chance of a confirmed molecular diagnosis of CMS was significantly higher for group A and lower for group C. Some individual clinical features, alterations on biopsy and electrophysiology enhanced specificity for CMS. Muscle imaging showed at least mild alterations in the majority of confirmed cases, with preferential involvement of soleus, especially in CHRNE CMS. CONCLUSIONS Stricter clinical criteria increase the chance of confirming a CMS diagnosis, but may lose sensitivity, especially for some specific genes.
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Affiliation(s)
- Eduardo P Estephan
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil.,Department of Neurology, Hospital Santa Marcelina, Sao Paulo, Brazil.,Department of Medical Clinic, Faculdade de Medicina Santa Marcelina (FASM), Sao Paulo, Brazil
| | - Antonio A Zambon
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
| | - Rachel Thompson
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Kiran Polavarapu
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Danny Jomaa
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.,Queen's University School of Medicine, Kingston, ON, Canada
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, University of Newcastle, Newcastle upon Tyne, UK
| | - Paulo V P Helito
- Department of Radiology, Hospital das Clínicas (HCFMUSP), Instituto de Ortopedia (IOT), Sao Paulo, Brazil
| | - Carlos O Heise
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
| | - Cristiane A M Moreno
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil.,Department of Neurology, Hospital Santa Marcelina, Sao Paulo, Brazil.,Department of Medical Clinic, Faculdade de Medicina Santa Marcelina (FASM), Sao Paulo, Brazil
| | - André M S Silva
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
| | - Joao A Kouyoumdjian
- Faculdade Estadual de Medicina de Sao Jose do Rio Preto (FAMERP), Sao Jose do Rio Preto, Brazil
| | - Maria da Penha Morita
- Faculdade Estadual de Medicina de Sao Jose do Rio Preto (FAMERP), Sao Jose do Rio Preto, Brazil
| | - Umbertina C Reed
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
| | - Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.,Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada.,Department of Medicine, Ottawa Research Institute, Ottawa, ON, Canada.,Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, University Medical Center Freiburg, Freiburg, Germany.,Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Edmar Zanoteli
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
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14
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Ramdas S, Beeson D. Congenital myasthenic syndromes: where do we go from here? Neuromuscul Disord 2021; 31:943-954. [PMID: 34736634 DOI: 10.1016/j.nmd.2021.07.400] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/22/2021] [Accepted: 07/27/2021] [Indexed: 11/27/2022]
Abstract
Congenital myasthenia syndromes are rare but often treatable conditions affecting neuromuscular transmission. They result from loss or impaired function of one of a number of proteins secondary to a genetic defect. An estimate of the prevalence in the UK gave 9.2 cases per million, however, this is likely an underestimate since the adoption of next generation sequencing for diagnosis away from specialist centres is enhancing the 'pick up' rate. Next generation sequencing has helped identify a series of novel genes that harbour mutations causative for congenital myasthenic syndrome that include not only genes that encode proteins specifically expressed at the neuromuscular junction but also those that are ubiquitously expressed. The list of genes harbouring disease-causing mutations for congenital myasthenic syndrome continues to expand and is now over 30, but with many of the newly identified genes it is increasingly being recognised that abnormal neuromuscular transmission is only one component of a multifaceted phenotype in which muscle, the central nervous system, and other organs may also be affected. Treatment can be tailored to the underlying molecular mechanism for impaired neuromuscular transmission but treating the more complex multifaceted disorders and will require development of new therapies.
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Affiliation(s)
- Sithara Ramdas
- MDUK Neuromuscular centre, Children's Hospital, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - David Beeson
- Neurosciences Group, Weatherall Institute of Molecular Medicine, The John Radcliffe, Oxford OX3 9DS, UK.
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15
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Abstract
SNARE proteins and Sec1/Munc18 (SM) proteins constitute the core molecular engine that drives nearly all intracellular membrane fusion and exocytosis. While SNAREs are known to couple their folding and assembly to membrane fusion, the physiological pathways of SNARE assembly and the mechanistic roles of SM proteins have long been enigmatic. Here, we review recent advances in understanding the SNARE-SM fusion machinery with an emphasis on biochemical and biophysical studies of proteins that mediate synaptic vesicle fusion. We begin by discussing the energetics, pathways, and kinetics of SNARE folding and assembly in vitro. Then, we describe diverse interactions between SM and SNARE proteins and their potential impact on SNARE assembly in vivo. Recent work provides strong support for the idea that SM proteins function as chaperones, their essential role being to enable fast, accurate SNARE assembly. Finally, we review the evidence that SM proteins collaborate with other SNARE chaperones, especially Munc13-1, and briefly discuss some roles of SNARE and SM protein deficiencies in human disease.
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Affiliation(s)
- Yongli Zhang
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520, USA;
| | - Frederick M Hughson
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA;
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16
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John A, Ng-Cordell E, Hanna N, Brkic D, Baker K. The neurodevelopmental spectrum of synaptic vesicle cycling disorders. J Neurochem 2021; 157:208-228. [PMID: 32738165 DOI: 10.1111/jnc.15135] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 07/20/2020] [Accepted: 07/21/2020] [Indexed: 12/11/2022]
Abstract
In this review, we describe and discuss neurodevelopmental phenotypes arising from rare, high penetrance genomic variants which directly influence synaptic vesicle cycling (SVC disorders). Pathogenic variants in each SVC disorder gene lead to disturbance of at least one SVC subprocess, namely vesicle trafficking (e.g. KIF1A and GDI1), clustering (e.g. TRIO, NRXN1 and SYN1), docking and priming (e.g. STXBP1), fusion (e.g. SYT1 and PRRT2) or re-uptake (e.g. DNM1, AP1S2 and TBC1D24). We observe that SVC disorders share a common set of neurological symptoms (movement disorders, epilepsies), cognitive impairments (developmental delay, intellectual disabilities, cerebral visual impairment) and mental health difficulties (autism, ADHD, psychiatric symptoms). On the other hand, there is notable phenotypic variation between and within disorders, which may reflect selective disruption to SVC subprocesses, spatiotemporal and cell-specific gene expression profiles, mutation-specific effects, or modifying factors. Understanding the common cellular and systems mechanisms underlying neurodevelopmental phenotypes in SVC disorders, and the factors responsible for variation in clinical presentations and outcomes, may translate to personalized clinical management and improved quality of life for patients and families.
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Affiliation(s)
- Abinayah John
- MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, UK
| | - Elise Ng-Cordell
- MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, UK
| | - Nancy Hanna
- MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, UK
| | - Diandra Brkic
- MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, UK
| | - Kate Baker
- MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, UK
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17
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Wang Z, Li J, Zhang T, Lu T, Wang H, Jia M, Liu J, Xiong J, Zhang D, Wang L. Family-based association study identifies SNAP25 as a susceptibility gene for autism in the Han Chinese population. Prog Neuropsychopharmacol Biol Psychiatry 2021; 105:109985. [PMID: 32479779 DOI: 10.1016/j.pnpbp.2020.109985] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 05/09/2020] [Accepted: 05/26/2020] [Indexed: 11/18/2022]
Abstract
Autism is a neurodevelopmental disorder with high heritability. Synaptosome associated protein 25 (SNAP25) encodes a presynaptic membrane-binding protein. It plays a crucial role in neurotransmission and may be involved in the pathogenesis of autism. However, the association between SNAP25 and autism in the Han Chinese population remains unclear. To investigate whether single nucleotide polymorphisms (SNPs) in SNAP25 contribute to the risk of autism, we performed a family-based association study of 14 tagSNPs in SNAP25 in 640 Han Chinese autism trios. Our results demonstrated that rs363018 in SNAP25 was significantly associated with autism under both additive (A > G, Z = 3.144, P = .0017) and recessive models (A > G, Z = 3.055, P = .0023) after Bonferroni correction (P < .0036). An additional SNP, rs8636, was nominally associated with autism under the recessive model (C > T, Z = 1.972, P = .0487). Haplotype-based association test revealed that haplotypes A-T (Z = 2.038, P = .0415) and G-T (Z = -3.114, P = .0018) of rs363018-rs362582 were significantly associated with autism after the permutation test (P = .0158). These findings suggest that SNAP25 may represent a susceptibility gene for autism in the Han Chinese population.
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Affiliation(s)
- Ziqi Wang
- Peking University Sixth Hospital, Beijing 100191, China; Peking University Institute of Mental Health, Beijing 100191, China; NHC Key Laboratory of Mental Health (Peking University), Beijing 100191, China; National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Beijing 100191, China
| | - Jun Li
- Peking University Sixth Hospital, Beijing 100191, China; Peking University Institute of Mental Health, Beijing 100191, China; NHC Key Laboratory of Mental Health (Peking University), Beijing 100191, China; National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Beijing 100191, China
| | - Tian Zhang
- Peking University Sixth Hospital, Beijing 100191, China; Peking University Institute of Mental Health, Beijing 100191, China; NHC Key Laboratory of Mental Health (Peking University), Beijing 100191, China; National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Beijing 100191, China
| | - Tianlan Lu
- Peking University Sixth Hospital, Beijing 100191, China; Peking University Institute of Mental Health, Beijing 100191, China; NHC Key Laboratory of Mental Health (Peking University), Beijing 100191, China; National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Beijing 100191, China
| | - Han Wang
- Peking University Sixth Hospital, Beijing 100191, China; Peking University Institute of Mental Health, Beijing 100191, China; NHC Key Laboratory of Mental Health (Peking University), Beijing 100191, China; National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Beijing 100191, China
| | - Meixiang Jia
- Peking University Sixth Hospital, Beijing 100191, China; Peking University Institute of Mental Health, Beijing 100191, China; NHC Key Laboratory of Mental Health (Peking University), Beijing 100191, China; National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Beijing 100191, China
| | - Jing Liu
- Peking University Sixth Hospital, Beijing 100191, China; Peking University Institute of Mental Health, Beijing 100191, China; NHC Key Laboratory of Mental Health (Peking University), Beijing 100191, China; National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Beijing 100191, China.
| | - Jun Xiong
- Haidian Maternal & Child Health Hospital, Beijing 100080, China.
| | - Dai Zhang
- Peking University Sixth Hospital, Beijing 100191, China; Peking University Institute of Mental Health, Beijing 100191, China; NHC Key Laboratory of Mental Health (Peking University), Beijing 100191, China; National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Beijing 100191, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China; PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Lifang Wang
- Peking University Sixth Hospital, Beijing 100191, China; Peking University Institute of Mental Health, Beijing 100191, China; NHC Key Laboratory of Mental Health (Peking University), Beijing 100191, China; National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Beijing 100191, China.
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18
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An iPSC-based neural model of sialidosis uncovers glycolytic impairment-causing presynaptic dysfunction and deregulation of Ca 2+ dynamics. Neurobiol Dis 2021; 152:105279. [PMID: 33516873 DOI: 10.1016/j.nbd.2021.105279] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 01/22/2021] [Accepted: 01/25/2021] [Indexed: 12/21/2022] Open
Abstract
Sialidosis is a neuropathic lysosomal storage disease caused by a deficiency in the NEU1 gene-encoding lysosomal neuraminidase and characterized by abnormal accumulation of undigested sialyl-oligoconjugates in systemic organs including brain. Although patients exhibit neurological symptoms, the underlying neuropathological mechanism remains unclear. Here, we generated induced pluripotent stem cells (iPSCs) from skin fibroblasts with sialidosis and induced the differentiation into neural progenitor cells (NPCs) and neurons. Sialidosis NPCs and neurons mimicked the disease-like phenotypes including reduced neuraminidase activity, accumulation of sialyl-oligoconjugates and lysosomal expansions. Functional analysis also revealed that sialidosis neurons displayed two distinct abnormalities, defective exocytotic glutamate release and augmented α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptor (AMPAR)-mediated Ca2+ influx. These abnormalities were restored by overexpression of the wild-type NEU1 gene, demonstrating causative role of neuraminidase deficiency in functional impairments of disease neurons. Comprehensive proteomics analysis revealed the significant reduction of SNARE proteins and glycolytic enzymes in synaptosomal fraction, with downregulation of ATP production. Bypassing the glycolysis by treatment of pyruvate, which is final metabolite of glycolysis pathway, improved both the synaptsomal ATP production and the exocytotic function. We also found that upregulation of AMPAR and L-type voltage dependent Ca2+ channel (VDCC) subunits in disease neurons, with the restoration of AMPAR-mediated Ca2+ over-load by treatment of antagonists for the AMPAR and L-type VDCC. Our present study provides new insights into both the neuronal pathophysiology and potential therapeutic strategy for sialidosis.
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19
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Rodríguez Cruz PM, Hughes I, Manzur A, Munot P, Ramdas S, Wright R, Breen C, Pitt M, Pagnamenta AT, Taylor JC, Palace J, Beeson D. Presynaptic congenital myasthenic syndrome due to three novel mutations in SLC5A7 encoding the sodium-dependant high-affinity choline transporter. Neuromuscul Disord 2021; 31:21-28. [DOI: 10.1016/j.nmd.2020.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 10/13/2020] [Accepted: 10/15/2020] [Indexed: 01/14/2023]
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20
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Klöckner C, Sticht H, Zacher P, Popp B, Babcock HE, Bakker DP, Barwick K, Bonfert MV, Bönnemann CG, Brilstra EH, Chung WK, Clarke AJ, Devine P, Donkervoort S, Fraser JL, Friedman J, Gates A, Ghoumid J, Hobson E, Horvath G, Keller-Ramey J, Keren B, Kurian MA, Lee V, Leppig KA, Lundgren J, McDonald MT, McLaughlin HM, McTague A, Mefford HC, Mignot C, Mikati MA, Nava C, Raymond FL, Sampson JR, Sanchis-Juan A, Shashi V, Shieh JTC, Shinawi M, Slavotinek A, Stödberg T, Stong N, Sullivan JA, Taylor AC, Toler TL, van den Boogaard MJ, van der Crabben SN, van Gassen KLI, van Jaarsveld RH, Van Ziffle J, Wadley AF, Wagner M, Wigby K, Wortmann SB, Zarate YA, Møller RS, Lemke JR, Platzer K. De novo variants in SNAP25 cause an early-onset developmental and epileptic encephalopathy. Genet Med 2020; 23:653-660. [PMID: 33299146 DOI: 10.1038/s41436-020-01020-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 10/12/2020] [Accepted: 10/13/2020] [Indexed: 11/09/2022] Open
Abstract
PURPOSE This study aims to provide a comprehensive description of the phenotypic and genotypic spectrum of SNAP25 developmental and epileptic encephalopathy (SNAP25-DEE) by reviewing newly identified and previously reported individuals. METHODS Individuals harboring heterozygous missense or loss-of-function variants in SNAP25 were assembled through collaboration with international colleagues, matchmaking platforms, and literature review. For each individual, detailed phenotyping, classification, and structural modeling of the identified variant were performed. RESULTS The cohort comprises 23 individuals with pathogenic or likely pathogenic de novo variants in SNAP25. Intellectual disability and early-onset epilepsy were identified as the core symptoms of SNAP25-DEE, with recurrent findings of movement disorders, cerebral visual impairment, and brain atrophy. Structural modeling for all variants predicted possible functional defects concerning SNAP25 or impaired interaction with other components of the SNARE complex. CONCLUSION We provide a comprehensive description of SNAP25-DEE with intellectual disability and early-onset epilepsy mostly occurring before the age of two years. These core symptoms and additional recurrent phenotypes show an overlap to genes encoding other components or associated proteins of the SNARE complex such as STX1B, STXBP1, or VAMP2. Thus, these findings advance the concept of a group of neurodevelopmental disorders that may be termed "SNAREopathies."
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Affiliation(s)
- Chiara Klöckner
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Heinrich Sticht
- Institute of Biochemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Pia Zacher
- The Saxon Epilepsy Center Kleinwachau, Radeberg, Germany
| | - Bernt Popp
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Holly E Babcock
- Rare Disease Institute, Children's National Hospital, Washington, DC, USA
| | - Dewi P Bakker
- Department of Child Neurology, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Katy Barwick
- Institute of Child Health, University Collge London, London, UK
| | - Michaela V Bonfert
- Department of Pediatric Neurology and Developmental Medicine and LMU Center for Children with Medical Complexity, Dr. von Hauner Children's Hospital, LMU - University Hospital, Ludwig-Maximilians-Universität, Munich, Germany
| | - Carsten G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Eva H Brilstra
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Wendy K Chung
- Departments of Pediatrics and Medicine, Columbia University Medical Center, New York, NY, USA
| | - Angus J Clarke
- Division of Cancer & Genetics, School of Medicine, Cardiff University, Wales, UK
| | - Patrick Devine
- Department of Pathology, University of California San Francisco, San Francisco, CA, USA
| | - Sandra Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Jamie L Fraser
- Rare Disease Institute, Division of Genetics and Metabolism, Children's National Hospital, Washington, DC, USA
| | - Jennifer Friedman
- Departments of Neurosciences and Pediatrics, University of California San Diego and Division of Neurology, Rady Children's Hospital, San Diego, CA, USA.,Rady Children's Institute for Genomic Medicine, San Diego, CA, USA
| | - Alyssa Gates
- Department of Genetic Services, Kaiser Permanente Washington, Seattle, WA, USA
| | - Jamal Ghoumid
- Service de Génétique Clinique, Hôpital Jeanne de Flandre, CHU Lille, Lille, France
| | - Emma Hobson
- Yorkshire Clinical Genetics Service, Chapel Allerton Hospital, Leeds, UK
| | - Gabriella Horvath
- Department of Pediatrics, Division of Biochemical Diseases, University of British Columbia, Vancouver, Canada
| | | | - Boris Keren
- APHP, Département de Génétique, Groupe Hospitalier Pitié Salpêtrière, Paris, France
| | - Manju A Kurian
- Institute of Child Health, University Collge London, London, UK
| | - Virgina Lee
- Department of Neurology, University of California San Francisco, San Francisco, CA, USA
| | - Kathleen A Leppig
- Department of Genetic Services, Kaiser Permanente Washington, Seattle, WA, USA
| | - Johan Lundgren
- Institute of Clinical Sciences, Skane University Hospital, Lund, Sweden
| | - Marie T McDonald
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | | | - Amy McTague
- Institute of Child Health, University Collge London, London, UK
| | - Heather C Mefford
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - Cyril Mignot
- Département de Génétique, Centre de Référence Déficiences Intellectuelles de Causes Rares, Groupe Hospitalier Pitié Salpêtrière et Hôpital Trousseau, APHP, Sorbonne Université, Paris, France
| | - Mohamad A Mikati
- Division of Pediatric Neurology, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | - Caroline Nava
- Sorbonne University, Paris Brain Institute, Inserm U1127, CNRS UMR 7225, AP-HP, Pitié Salpêtrière Hospital, Department of Genetics, Paris, France
| | - F Lucy Raymond
- NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, UK.,Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Julian R Sampson
- Division of Cancer & Genetics, School of Medicine, Cardiff University, Wales, UK
| | - Alba Sanchis-Juan
- NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, UK.,Department of Haematology, University of Cambridge, NHS Blood and Transplant Centre, Cambridge, UK
| | - Vandana Shashi
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | - Joseph T C Shieh
- Division of Medical Genetics, University of California, San Francisco, San Francisco, CA, USA.,Institute for Human Genetics, University of California, San Francisco, San Francisco, CA, USA
| | - Marwan Shinawi
- Department of Pediatrics, Division of Genetics and Genomic Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Anne Slavotinek
- Division of Medical Genetics, University of California, San Francisco, San Francisco, CA, USA
| | - Tommy Stödberg
- Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
| | - Nicholas Stong
- Institute for Genomic Medicine, Columbia University, New York, NY, USA
| | - Jennifer A Sullivan
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | - Ashley C Taylor
- Section of Genetics, Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Tomi L Toler
- Department of Pediatrics, Division of Genetics and Genomic Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | | | - Saskia N van der Crabben
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Koen L I van Gassen
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Jessica Van Ziffle
- Department of Pathology, University of California San Francisco, San Francisco, CA, USA
| | | | - Matias Wagner
- Institute of Neurogenomics, Helmholtz Zentrum Munich, Neuherberg, Germany
| | - Kristen Wigby
- Department of Pediatrics, Division of Genetics, University of California, San Diego and Rady Children's Hospital-San Diego, San Diego, CA, USA
| | - Saskia B Wortmann
- Amalia Children's Hospital, Radboud University Nijmegen, Nijmegen, The Netherlands.,University Childrens Hospital, Paracelsus Medical University, Salzburg, Austria
| | - Yuri A Zarate
- Section of Genetics and Metabolism, Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Rikke S Møller
- Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark.,Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Centre Filadelfia, Dianalund, Denmark
| | - Johannes R Lemke
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Konrad Platzer
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany.
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21
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Li Y, Wang C, Wang P, Li X, Zhou L. Effects of febrile seizures in mesial temporal lobe epilepsy with hippocampal sclerosis on gene expression using bioinformatical analysis. ACTA EPILEPTOLOGICA 2020. [DOI: 10.1186/s42494-020-00027-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
AbstractBackgroundTo investigate the effect of long-term febrile convulsions on gene expression in mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) and explore the molecular mechanism of MTLE-HS.MethodsMicroarray data of MTLE-HS were obtained from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) between MTLE-HS with and without febrile seizure history were screened by the GEO2R software. Pathway enrichment and gene ontology of the DEGs were analyzed using the DAVID online database and FunRich software. Protein–protein interaction (PPI) networks among DEGs were constructed using the STRING database and analyzed by Cytoscape.ResultsA total of 515 DEGs were identified in MTLE-HS samples with a febrile seizure history compared to MTLE-HS samples without febrile seizure, including 25 down-regulated and 490 up-regulated genes. These DEGs were expressed mostly in plasma membrane and synaptic vesicles. The major molecular functions of those genes were voltage-gated ion channel activity, extracellular ligand-gated ion channel activity and calcium ion binding. The DEGs were mainly involved in biological pathways of cell communication signal transduction and transport. Five genes (SNAP25, SLC32A1, SYN1, GRIN1,andGRIA1) were significantly expressed in the MTLE-HS with prolonged febrile seizures.ConclusionThe pathogenesis of MTLE-HS involves multiple genes, and prolonged febrile seizures could cause differential expression of genes. Thus, investigations of those genes may provide a new perspective into the mechanism of MTLE-HS.
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22
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Alten B, Zhou Q, Shin OH, Esquivies L, Lin PY, White KI, Sun R, Chung WK, Monteggia LM, Brunger AT, Kavalali ET. Role of Aberrant Spontaneous Neurotransmission in SNAP25-Associated Encephalopathies. Neuron 2020; 109:59-72.e5. [PMID: 33147442 DOI: 10.1016/j.neuron.2020.10.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 09/09/2020] [Accepted: 10/07/2020] [Indexed: 01/19/2023]
Abstract
SNARE (soluble N-ethylmaleimide sensitive factor attachment protein receptor) complex, composed of synaptobrevin, syntaxin, and SNAP25, forms the essential fusion machinery for neurotransmitter release. Recent studies have reported several mutations in the gene encoding SNAP25 as a causative factor for developmental and epileptic encephalopathies of infancy and childhood with diverse clinical manifestations. However, it remains unclear how SNAP25 mutations give rise to these disorders. Here, we show that although structurally clustered mutations in SNAP25 give rise to related synaptic transmission phenotypes, specific alterations in spontaneous neurotransmitter release are a key factor to account for disease heterogeneity. Importantly, we identified a single mutation that augments spontaneous release without altering evoked release, suggesting that aberrant spontaneous release is sufficient to cause disease in humans.
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Affiliation(s)
- Baris Alten
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37240-7933, USA
| | - Qiangjun Zhou
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37240-7933, USA; Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240-7933, USA
| | - Ok-Ho Shin
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37240-7933, USA
| | - Luis Esquivies
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Pei-Yi Lin
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37240-7933, USA
| | - K Ian White
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Rong Sun
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37240-7933, USA; Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240-7933, USA
| | - Wendy K Chung
- Department of Pediatrics (in Medicine), Columbia University Medical Center, New York, NY 10032, USA
| | - Lisa M Monteggia
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37240-7933, USA
| | - Axel T Brunger
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Ege T Kavalali
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37240-7933, USA.
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23
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Melland H, Carr EM, Gordon SL. Disorders of synaptic vesicle fusion machinery. J Neurochem 2020; 157:130-164. [PMID: 32916768 DOI: 10.1111/jnc.15181] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/20/2020] [Accepted: 08/26/2020] [Indexed: 12/11/2022]
Abstract
The revolution in genetic technology has ushered in a new age for our understanding of the underlying causes of neurodevelopmental, neuromuscular and neurodegenerative disorders, revealing that the presynaptic machinery governing synaptic vesicle fusion is compromised in many of these neurological disorders. This builds upon decades of research showing that disturbance to neurotransmitter release via toxins can cause acute neurological dysfunction. In this review, we focus on disorders of synaptic vesicle fusion caused either by toxic insult to the presynapse or alterations to genes encoding the key proteins that control and regulate fusion: the SNARE proteins (synaptobrevin, syntaxin-1 and SNAP-25), Munc18, Munc13, synaptotagmin, complexin, CSPα, α-synuclein, PRRT2 and tomosyn. We discuss the roles of these proteins and the cellular and molecular mechanisms underpinning neurological deficits in these disorders.
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Affiliation(s)
- Holly Melland
- The Florey Institute of Neuroscience and Mental Health, Melbourne Dementia Research Centre, The University of Melbourne, Melbourne, Vic., Australia
| | - Elysa M Carr
- The Florey Institute of Neuroscience and Mental Health, Melbourne Dementia Research Centre, The University of Melbourne, Melbourne, Vic., Australia
| | - Sarah L Gordon
- The Florey Institute of Neuroscience and Mental Health, Melbourne Dementia Research Centre, The University of Melbourne, Melbourne, Vic., Australia
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24
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Tang BL. SNAREs and developmental disorders. J Cell Physiol 2020; 236:2482-2504. [PMID: 32959907 DOI: 10.1002/jcp.30067] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/20/2020] [Accepted: 09/09/2020] [Indexed: 12/12/2022]
Abstract
Members of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) family mediate membrane fusion processes associated with vesicular trafficking and autophagy. SNAREs mediate core membrane fusion processes essential for all cells, but some SNAREs serve cell/tissue type-specific exocytic/endocytic functions, and are therefore critical for various aspects of embryonic development. Mutations or variants of their encoding genes could give rise to developmental disorders, such as those affecting the nervous system and immune system in humans. Mutations to components in the canonical synaptic vesicle fusion SNARE complex (VAMP2, STX1A/B, and SNAP25) and a key regulator of SNARE complex formation MUNC18-1, produce variant phenotypes of autism, intellectual disability, movement disorders, and epilepsy. STX11 and MUNC18-2 mutations underlie 2 subtypes of familial hemophagocytic lymphohistiocytosis. STX3 mutations contribute to variant microvillus inclusion disease. Chromosomal microdeletions involving STX16 play a role in pseudohypoparathyroidism type IB associated with abnormal imprinting of the GNAS complex locus. In this short review, I discuss these and other SNARE gene mutations and variants that are known to be associated with a variety developmental disorders, with a focus on their underlying cellular and molecular pathological basis deciphered through disease modeling. Possible pathogenic potentials of other SNAREs whose variants could be disease predisposing are also speculated upon.
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Affiliation(s)
- Bor L Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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25
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Donkervoort S, Mohassel P, Laugwitz L, Zaki MS, Kamsteeg EJ, Maroofian R, Chao KR, Verschuuren-Bemelmans CC, Horber V, Fock AJM, McCarty RM, Jain MS, Biancavilla V, McMacken G, Nalls M, Voermans NC, Elbendary HM, Snyder M, Cai C, Lehky TJ, Stanley V, Iannaccone ST, Foley AR, Lochmüller H, Gleeson J, Houlden H, Haack TB, Horvath R, Bönnemann CG. Biallelic loss of function variants in SYT2 cause a treatable congenital onset presynaptic myasthenic syndrome. Am J Med Genet A 2020; 182:2272-2283. [PMID: 32776697 DOI: 10.1002/ajmg.a.61765] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 05/25/2020] [Accepted: 06/13/2020] [Indexed: 12/15/2022]
Abstract
Synaptotagmins are integral synaptic vesicle membrane proteins that function as calcium sensors and regulate neurotransmitter release at the presynaptic nerve terminal. Synaptotagmin-2 (SYT2), is the major isoform expressed at the neuromuscular junction. Recently, dominant missense variants in SYT2 have been reported as a rare cause of distal motor neuropathy and myasthenic syndrome, manifesting with stable or slowly progressive distal weakness of variable severity along with presynaptic NMJ impairment. These variants are thought to have a dominant-negative effect on synaptic vesicle exocytosis, although the precise pathomechanism remains to be elucidated. Here we report seven patients of five families, with biallelic loss of function variants in SYT2, clinically manifesting with a remarkably consistent phenotype of severe congenital onset hypotonia and weakness, with variable degrees of respiratory involvement. Electrodiagnostic findings were consistent with a presynaptic congenital myasthenic syndrome (CMS) in some. Treatment with an acetylcholinesterase inhibitor pursued in three patients showed clinical improvement with increased strength and function. This series further establishes SYT2 as a CMS-disease gene and expands its clinical and genetic spectrum to include recessive loss-of-function variants, manifesting as a severe congenital onset presynaptic CMS with potential treatment implications.
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Affiliation(s)
- Sandra Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Payam Mohassel
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Lucia Laugwitz
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany.,Department of Paediatric Neurology, University Children's Hospital, Tübingen, Germany
| | - Maha S Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Reza Maroofian
- Department of Neuromuscular Disorders, University College London Institute of Neurology, London, UK
| | - Katherine R Chao
- Center for Mendelian Genomics, Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | | | - Veronka Horber
- Department of Paediatric Neurology, University Children's Hospital, Tübingen, Germany
| | - Annemarie J M Fock
- Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Riley M McCarty
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Minal S Jain
- Rehabilitation Medicine Department, Clinical Research Center, National Institutes of Health, Bethesda, Maryland, USA
| | - Victoria Biancavilla
- Rehabilitation Medicine Department, Clinical Research Center, National Institutes of Health, Bethesda, Maryland, USA
| | - Grace McMacken
- Department of Neurosciences, Royal Victoria Hospital, Belfast, UK
| | - Matthew Nalls
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Nicol C Voermans
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Hasnaa M Elbendary
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Molly Snyder
- Department of Neurology, Children's Health, Dallas, Texas, USA
| | - Chunyu Cai
- Department of Pathology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Tanya J Lehky
- EMG Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Valentina Stanley
- Laboratory for Pediatric Brain Disease, Howard Hughes Medical Institute, University of California, San Diego, California, USA.,Rady Children's Institute for Genomic Medicine, Rady Children's Hospital, San Diego, California, USA
| | - Susan T Iannaccone
- Department of Pediatrics, UT Southwestern Medical Center, Dallas, Texas, USA
| | - A Reghan Foley
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Hanns Lochmüller
- Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada.,Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Joseph Gleeson
- Laboratory for Pediatric Brain Disease, Howard Hughes Medical Institute, University of California, San Diego, California, USA.,Rady Children's Institute for Genomic Medicine, Rady Children's Hospital, San Diego, California, USA
| | - Henry Houlden
- Department of Neuromuscular Disorders, University College London Institute of Neurology, London, UK
| | - Tobias B Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Carsten G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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26
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Meijer M, Rehbach K, Brunner JW, Classen JA, Lammertse HCA, van Linge LA, Schut D, Krutenko T, Hebisch M, Cornelisse LN, Sullivan PF, Peitz M, Toonen RF, Brüstle O, Verhage M. A Single-Cell Model for Synaptic Transmission and Plasticity in Human iPSC-Derived Neurons. Cell Rep 2020; 27:2199-2211.e6. [PMID: 31091456 DOI: 10.1016/j.celrep.2019.04.058] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 02/05/2019] [Accepted: 04/10/2019] [Indexed: 12/14/2022] Open
Abstract
Synaptic dysfunction is associated with many brain disorders, but robust human cell models to study synaptic transmission and plasticity are lacking. Instead, current in vitro studies on human neurons typically rely on spontaneous synaptic events as a proxy for synapse function. Here, we describe a standardized in vitro approach using human neurons cultured individually on glia microdot arrays that allow single-cell analysis of synapse formation and function. We show that single glutamatergic or GABAergic forebrain neurons differentiated from human induced pluripotent stem cells form mature synapses that exhibit robust evoked synaptic transmission. These neurons show plasticity features such as synaptic facilitation, depression, and recovery. Finally, we show that spontaneous events are a poor predictor of synaptic maturity and do not correlate with the robustness of evoked responses. This methodology can be deployed directly to evaluate disease models for synaptic dysfunction and can be leveraged for drug development and precision medicine.
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Affiliation(s)
- Marieke Meijer
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU Medical Center, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands
| | - Kristina Rehbach
- Institute of Reconstructive Neurobiology, University of Bonn School of Medicine & University Hospital Bonn, Bonn, Germany; LIFE&BRAIN GmbH, Cellomics Unit, 53127 Bonn, Germany
| | - Jessie W Brunner
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU Medical Center, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands
| | - Jessica A Classen
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU Medical Center, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands
| | - Hanna C A Lammertse
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU Medical Center, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands
| | - Lola A van Linge
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU Medical Center, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands
| | - Desiree Schut
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU Medical Center, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands
| | - Tamara Krutenko
- Institute of Reconstructive Neurobiology, University of Bonn School of Medicine & University Hospital Bonn, Bonn, Germany
| | - Matthias Hebisch
- Institute of Reconstructive Neurobiology, University of Bonn School of Medicine & University Hospital Bonn, Bonn, Germany
| | - L Niels Cornelisse
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU Medical Center, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands
| | - Patrick F Sullivan
- UNC Center for Psychiatric Genomics, University of North Carolina at Chapel Hill, 101 Manning Drive, Chapel Hill, NC 27599-7160, USA; Karolinska Institutet, Department of Medical Epidemiology and Biostatistics and Department of (Clinical) Genetics, Nobels Väg 12A, 171 77 Stockholm, Sweden
| | - Michael Peitz
- Institute of Reconstructive Neurobiology, University of Bonn School of Medicine & University Hospital Bonn, Bonn, Germany; Cell Programming Core Facility, University of Bonn School of Medicine, Bonn, Germany.
| | - Ruud F Toonen
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU Medical Center, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands
| | - Oliver Brüstle
- Institute of Reconstructive Neurobiology, University of Bonn School of Medicine & University Hospital Bonn, Bonn, Germany.
| | - Matthijs Verhage
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU Medical Center, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands; Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU Medical Center, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands.
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27
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Bonnycastle K, Davenport EC, Cousin MA. Presynaptic dysfunction in neurodevelopmental disorders: Insights from the synaptic vesicle life cycle. J Neurochem 2020; 157:179-207. [PMID: 32378740 DOI: 10.1111/jnc.15035] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/14/2020] [Accepted: 04/22/2020] [Indexed: 12/11/2022]
Abstract
The activity-dependent fusion, retrieval and recycling of synaptic vesicles is essential for the maintenance of neurotransmission. Until relatively recently it was believed that most mutations in genes that were essential for this process would be incompatible with life, because of this fundamental role. However, an ever-expanding number of mutations in this very cohort of genes are being identified in individuals with neurodevelopmental disorders, including autism, intellectual disability and epilepsy. This article will summarize the current state of knowledge linking mutations in presynaptic genes to neurodevelopmental disorders by sequentially covering the various stages of the synaptic vesicle life cycle. It will also discuss how perturbations of specific stages within this recycling process could translate into human disease. Finally, it will also provide perspectives on the potential for future therapy that are targeted to presynaptic function.
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Affiliation(s)
- Katherine Bonnycastle
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK
| | - Elizabeth C Davenport
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK
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28
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Verhage M, Sørensen JB. SNAREopathies: Diversity in Mechanisms and Symptoms. Neuron 2020; 107:22-37. [PMID: 32559416 DOI: 10.1016/j.neuron.2020.05.036] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/29/2020] [Accepted: 05/26/2020] [Indexed: 12/14/2022]
Abstract
Neuronal SNAREs and their key regulators together drive synaptic vesicle exocytosis and synaptic transmission as a single integrated membrane fusion machine. Human pathogenic mutations have now been reported for all eight core components, but patients are diagnosed with very different neurodevelopmental syndromes. We propose to unify these syndromes, based on etiology and mechanism, as "SNAREopathies." Here, we review the strikingly diverse clinical phenomenology and disease severity and the also remarkably diverse genetic mechanisms. We argue that disease severity generally scales with functional redundancy and, conversely, that the large effect of mutations in some SNARE genes is the price paid for extensive integration and exceptional specialization. Finally, we discuss how subtle differences in components being rate limiting in different types of neurons helps to explain the main symptoms.
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Affiliation(s)
- Matthijs Verhage
- Department of Functional Genomics, Vrije Universiteit (VU) Amsterdam, De Boelelaan 1085, Amsterdam 1081 HV, the Netherlands; Department of Clinical Genetics, UMC Amsterdam, De Boelelaan 1085, Amsterdam 1081 HV, the Netherlands.
| | - Jakob B Sørensen
- Department of Neuroscience, University of Copenhagen, 2200 Copenhagen N, Denmark.
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29
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Xiao T, Wu LW. [Advances in the diagnosis and treatment of congenital myasthenic syndrome]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2020; 22:672-676. [PMID: 32571471 PMCID: PMC7390217 DOI: 10.7499/j.issn.1008-8830.1912095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/24/2020] [Indexed: 06/11/2023]
Abstract
Congenital myasthenic syndrome (CMS) is a group of clinical and genetic heterogeneous diseases caused by impaired neuromuscular transmission due to genetic defects. At present, it has been reported that more than 30 genes can cause CMS. All CMS subtypes have the clinical features of fatigue and muscle weakness, but age of onset, symptoms, and treatment response vary with the molecular mechanisms underlying genetic defects. Pharmacotherapy and symptomatic/supportive treatment are the main methods for the treatment of CMS, and antisense oligonucleotide technology has been proven to be beneficial for CHRNA 1-related CMS in animals. Since CMS is a group of increasingly recognized clinical and genetic heterogeneous diseases, an understanding of the latest knowledge and research advances in its clinical features, genetic research, and treatment helps to give early diagnosis and treatment as well as gain a deeper understanding of the pathogenesis of CMS, so as to make new breakthroughs in the treatment of CMS.
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Affiliation(s)
- Ting Xiao
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha 410008, China.
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30
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Xiao T, Wu LW. [Advances in the diagnosis and treatment of congenital myasthenic syndrome]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2020; 22:672-676. [PMID: 32571471 PMCID: PMC7390217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/24/2020] [Indexed: 11/12/2023]
Abstract
Congenital myasthenic syndrome (CMS) is a group of clinical and genetic heterogeneous diseases caused by impaired neuromuscular transmission due to genetic defects. At present, it has been reported that more than 30 genes can cause CMS. All CMS subtypes have the clinical features of fatigue and muscle weakness, but age of onset, symptoms, and treatment response vary with the molecular mechanisms underlying genetic defects. Pharmacotherapy and symptomatic/supportive treatment are the main methods for the treatment of CMS, and antisense oligonucleotide technology has been proven to be beneficial for CHRNA 1-related CMS in animals. Since CMS is a group of increasingly recognized clinical and genetic heterogeneous diseases, an understanding of the latest knowledge and research advances in its clinical features, genetic research, and treatment helps to give early diagnosis and treatment as well as gain a deeper understanding of the pathogenesis of CMS, so as to make new breakthroughs in the treatment of CMS.
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Affiliation(s)
- Ting Xiao
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha 410008, China.
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31
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The congenital myasthenic syndromes: expanding genetic and phenotypic spectrums and refining treatment strategies. Curr Opin Neurol 2020; 32:696-703. [PMID: 31361628 PMCID: PMC6735524 DOI: 10.1097/wco.0000000000000736] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Congenital myasthenic syndromes (CMS) are a group of heterogeneous inherited disorders caused by mutations in genes encoding proteins whose function is essential for the integrity of neuromuscular transmission. This review updates the reader on the expanding phenotypic spectrum and suggested improved treatment strategies.
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32
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Yarwood R, Hellicar J, Woodman PG, Lowe M. Membrane trafficking in health and disease. Dis Model Mech 2020; 13:13/4/dmm043448. [PMID: 32433026 PMCID: PMC7197876 DOI: 10.1242/dmm.043448] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Membrane trafficking pathways are essential for the viability and growth of cells, and play a major role in the interaction of cells with their environment. In this At a Glance article and accompanying poster, we outline the major cellular trafficking pathways and discuss how defects in the function of the molecular machinery that mediates this transport lead to various diseases in humans. We also briefly discuss possible therapeutic approaches that may be used in the future treatment of trafficking-based disorders. Summary: This At a Glance article and poster summarise the major intracellular membrane trafficking pathways and associated molecular machineries, and describe how defects in these give rise to disease in humans.
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Affiliation(s)
- Rebecca Yarwood
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
| | - John Hellicar
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
| | - Philip G Woodman
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
| | - Martin Lowe
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
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33
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Zhang Y, Cheng X, Luo C, Lei M, Mao F, Shi Z, Cao W, Zhang J, Zhang Q. Congenital Myasthenic Syndrome Caused by a Novel Hemizygous CHAT Mutation. Front Pediatr 2020; 8:185. [PMID: 32411636 PMCID: PMC7198756 DOI: 10.3389/fped.2020.00185] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 03/30/2020] [Indexed: 02/02/2023] Open
Abstract
Congenital myasthenic syndrome (CMS) is a neuromuscular transmission disorder caused by mutations in genes encoding neuromuscular junction proteins. CMS due to choline acetyltransferase (CHAT) gene mutation is characterized by episodic apnoea. To date, 52 cases of CMS caused by CHAT gene mutations have been reported. Here, we report a neonate with the third hemizygous mutation [a 4.9 Mb deletion [10q11.22-10q11.23 (chr10: 46123781-51028772)] containing the whole CHAT gene and c.1976A>T (p.Gln659Leu in the CHAT gene)]. The c.1976A>T (p.Gln659Leu) variant had not been reported in the ExAC or gnomAD databases and was predicted to be pathogenic. The alignment of amino acid sequences revealed that glutamine at codon 659 is highly conserved in different species and causes structural changes in the substrate-binding site. Our female patient with neonate-onset CMS presented with apnoea, dyspnoea, feeding difficulties, weak crying, and seizure-like episodes, and her respiration was ventilator dependent. The prostigmine test was positive. This case may help to further elucidate clinical features and treatment methods in neonate-onset CMS caused by CHAT gene mutations.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Qian Zhang
- Neonatal Intensive Care Unit, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
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Maselli RA, van der Linden H, Ferns M. Recessive congenital myasthenic syndrome caused by a homozygous mutation in SYT2 altering a highly conserved C-terminal amino acid sequence. Am J Med Genet A 2020; 182:1744-1749. [PMID: 32250532 DOI: 10.1002/ajmg.a.61579] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 02/05/2020] [Accepted: 03/19/2020] [Indexed: 12/19/2022]
Abstract
Defects in the gene encoding synaptotagmin 2 (SYT2) have been linked to a presynaptic congenital myasthenic syndrome (CMS) and motor neuropathies. However, to date only dominant forms of the disease have been described. We report here a consanguineous patient with a severe recessive form of presynaptic CMS and denervation atrophy caused by the homozygous mutation c.1191delG, p.Arg397Serfs*37 in SYT2. The affected 2-year-old girl had profound weakness and areflexia with moderate bulbar deficit. Repetitive nerve stimulation revealed an extreme reduction of compound muscle action potential amplitudes at rest, with a striking facilitation followed by a progressive decline at fast stimulation rates. These findings were reminiscent, but not identical to those seen in the Lambert-Eaton myasthenic syndrome. 3,4 diaminopyridine and pyridostigmine were effective to ameliorate muscle fatigue, but albuterol was ineffective. Modeling of the mutation using the rat Syt1 C2B x-ray structure revealed that Arg397Serfs*37 disrupts a highly conserved amino acid sequence at the bottom face of the C2B domain not directly involved in calcium binding, but crucial for synaptotagmin-SNARE interaction and exocytosis. Thus, this report describes a recessive form of synaptotagmin 2-CMS and highlights the importance of the synaptotagmin C-terminal on synaptic vesicle fusion and exocytosis.
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Affiliation(s)
- Ricardo A Maselli
- Department of Neurology, University of California Davis, Sacramento, California, USA
| | | | - Michael Ferns
- Department of Anesthesiology, University of California Davis, Davis, California, USA
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Chen W, Cai ZL, Chao ES, Chen H, Longley CM, Hao S, Chao HT, Kim JH, Messier JE, Zoghbi HY, Tang J, Swann JW, Xue M. Stxbp1/Munc18-1 haploinsufficiency impairs inhibition and mediates key neurological features of STXBP1 encephalopathy. eLife 2020; 9:e48705. [PMID: 32073399 PMCID: PMC7056272 DOI: 10.7554/elife.48705] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 02/18/2020] [Indexed: 12/11/2022] Open
Abstract
Mutations in genes encoding synaptic proteins cause many neurodevelopmental disorders, with the majority affecting postsynaptic apparatuses and much fewer in presynaptic proteins. Syntaxin-binding protein 1 (STXBP1, also known as MUNC18-1) is an essential component of the presynaptic neurotransmitter release machinery. De novo heterozygous pathogenic variants in STXBP1 are among the most frequent causes of neurodevelopmental disorders including intellectual disabilities and epilepsies. These disorders, collectively referred to as STXBP1 encephalopathy, encompass a broad spectrum of neurologic and psychiatric features, but the pathogenesis remains elusive. Here we modeled STXBP1 encephalopathy in mice and found that Stxbp1 haploinsufficiency caused cognitive, psychiatric, and motor dysfunctions, as well as cortical hyperexcitability and seizures. Furthermore, Stxbp1 haploinsufficiency reduced cortical inhibitory neurotransmission via distinct mechanisms from parvalbumin-expressing and somatostatin-expressing interneurons. These results demonstrate that Stxbp1 haploinsufficient mice recapitulate cardinal features of STXBP1 encephalopathy and indicate that GABAergic synaptic dysfunction is likely a crucial contributor to disease pathogenesis.
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Affiliation(s)
- Wu Chen
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s HospitalHoustonUnited States
| | - Zhao-Lin Cai
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s HospitalHoustonUnited States
| | - Eugene S Chao
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s HospitalHoustonUnited States
| | - Hongmei Chen
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s HospitalHoustonUnited States
| | - Colleen M Longley
- The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s HospitalHoustonUnited States
- Program in Developmental Biology, Baylor College of MedicineHoustonUnited States
| | - Shuang Hao
- Department of Pediatrics, Division of Neurology and Developmental Neuroscience, Baylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s HospitalHoustonUnited States
| | - Hsiao-Tuan Chao
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Department of Pediatrics, Division of Neurology and Developmental Neuroscience, Baylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s HospitalHoustonUnited States
- Department of Molecular and Human Genetics, Baylor College of MedicineHoustonUnited States
- McNair Medical Institute, The Robert and Janice McNair FoundationHoustonUnited States
| | - Joo Hyun Kim
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s HospitalHoustonUnited States
| | - Jessica E Messier
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s HospitalHoustonUnited States
| | - Huda Y Zoghbi
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Program in Developmental Biology, Baylor College of MedicineHoustonUnited States
- Department of Pediatrics, Division of Neurology and Developmental Neuroscience, Baylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s HospitalHoustonUnited States
- Department of Molecular and Human Genetics, Baylor College of MedicineHoustonUnited States
- Howard Hughes Medical Institute, Baylor College of MedicineHoustonUnited States
| | - Jianrong Tang
- Department of Pediatrics, Division of Neurology and Developmental Neuroscience, Baylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s HospitalHoustonUnited States
| | - John W Swann
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s HospitalHoustonUnited States
- Department of Pediatrics, Division of Neurology and Developmental Neuroscience, Baylor College of MedicineHoustonUnited States
| | - Mingshan Xue
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s HospitalHoustonUnited States
- Program in Developmental Biology, Baylor College of MedicineHoustonUnited States
- Department of Molecular and Human Genetics, Baylor College of MedicineHoustonUnited States
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36
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SNAP-25 Puts SNAREs at Center Stage in Metabolic Disease. Neuroscience 2019; 420:86-96. [DOI: 10.1016/j.neuroscience.2018.07.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/12/2018] [Accepted: 07/19/2018] [Indexed: 12/20/2022]
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37
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The SNAP-25 Protein Family. Neuroscience 2019; 420:50-71. [DOI: 10.1016/j.neuroscience.2018.09.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 08/31/2018] [Accepted: 09/14/2018] [Indexed: 01/04/2023]
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38
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Congenital myasthenic syndrome with mild intellectual disability caused by a recurrent SLC25A1 variant. Eur J Hum Genet 2019; 28:373-377. [PMID: 31527857 PMCID: PMC7029005 DOI: 10.1038/s41431-019-0506-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 08/26/2019] [Accepted: 08/29/2019] [Indexed: 11/10/2022] Open
Abstract
Congenital myasthenic syndromes (CMS) are a clinically and genetically heterogeneous group of disorders caused by mutations which lead to impaired neuromuscular transmission. SLC25A1 encodes a mitochondrial citrate carrier, associated mainly with the severe neurometabolic disease combined D-2- and L-2-hydroxyglutaric aciduria (D/L-2-HGA). We previously reported a single family with a homozygous missense variant in SLC25A1 with a phenotype restricted to relatively mild CMS with intellectual disability, but to date no additional cases of this CMS subtype had been reported. Here, we performed whole exome sequencing (WES) in three additional and unrelated families presenting with CMS and mild intellectual disability to identify the underlying causative gene. The WES analysis revealed the presence of a homozygous c.740G>A; p.(Arg247Gln) missense SLC25A1 variant, the same SLC25A1 variant as identified in the original family with this phenotype. Electron microscopy of muscle from two cases revealed enlarged and accumulated mitochondria. Haplotype analysis performed in two unrelated families suggested that this variant is a result of recurrent mutation and not a founder effect. This suggests that p.(Arg247Gln) is associated with a relatively mild CMS phenotype with subtle mitochondrial abnormalities, while other variants in this gene cause more severe neurometabolic disease. In conclusion, the p.(Arg247Gln) SLC25A1 variant should be considered in patients presenting with a presynaptic CMS phenotype, particularly with accompanying intellectual disability.
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39
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Casati M, Costa AS, Capitanio D, Ponzoni L, Ferri E, Agostini S, Lori E. The Biological Foundations of Sarcopenia: Established and Promising Markers. Front Med (Lausanne) 2019; 6:184. [PMID: 31457015 PMCID: PMC6700259 DOI: 10.3389/fmed.2019.00184] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 07/30/2019] [Indexed: 12/16/2022] Open
Abstract
Sarcopenia, the progressive loss of muscle mass and strength, is one of the major health issues in older adults, given its high prevalence accompanied by huge clinical and socioeconomic implications. Age-related changes in skeletal muscle can be attributed to mechanisms both directly and indirectly related to muscle homeostasis. Indeed, a wide spectrum of age-related modifications in the organism was shown to play a key role in the pathogenesis of sarcopenia. Not surprisingly, sarcopenia has sometimes been indicated as a syndrome stemming from the aging process, and not as univocal standalone disease. Due to the multidimensionality of sarcopenia, a single biomarker approach is not enough to explain the biology of this condition. The aim of this review is to suggest innovative and promising sarcopenia markers investigating the link between skeletal muscle and brain. Indeed, as a neurological origin of sarcopenia has been hypothesized, a new perspective on sarcopenia biomarkers may focus on the dysfunction of the neuromuscular junctions (NMJs). The core SNARE synaptosomal-associated protein of 25 kDa (SNAP25) accumulates in the plasma membrane of nerve terminals at NMJs and regulates exocytosis at peripheral and central synapses. Interestingly, mice studies have shown that SNAP25 affects the neuromuscular function. SNARE complex and, in particular, SNAP25 may represent a promising pathway to explore the molecular and cellular mechanisms regulating muscular homeostasis and concur at profiling the sarcopenia biological background.
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Affiliation(s)
- Martina Casati
- Geriatric Unit, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | | | - Daniele Capitanio
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | | | - Evelyn Ferri
- Geriatric Unit, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | | | - Elisa Lori
- Department of Biomedical and Clinical Sciences L. Sacco, University of Milan, Milan, Italy
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40
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Nicole S, Azuma Y, Bauché S, Eymard B, Lochmüller H, Slater C. Congenital Myasthenic Syndromes or Inherited Disorders of Neuromuscular Transmission: Recent Discoveries and Open Questions. J Neuromuscul Dis 2019; 4:269-284. [PMID: 29125502 PMCID: PMC5701762 DOI: 10.3233/jnd-170257] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Congenital myasthenic syndromes (CMS) form a heterogeneous group of rare diseases characterized by fatigable muscle weakness. They are genetically-inherited and caused by defective synaptic transmission at the cholinergic neuromuscular junction (NMJ). The number of genes known to cause CMS when mutated is currently 30, and the relationship between fatigable muscle weakness and defective functions is quite well-understood for many of them. However, some of the most recent discoveries in individuals with CMS challenge our knowledge of the NMJ, where the basis of the pathology has mostly been investigated in animal models. Frontier forms between CMS and congenital myopathy, which have been genetically and clinically identified, underline the poorly understood interplay between the synaptic and extrasynaptic molecules in the neuromuscular system. In addition, precise electrophysiological and histopathological investigations of individuals with CMS suggest an important role of NMJ plasticity in the response to CMS pathogenesis. While efficient drug-based treatments are already available to improve neuromuscular transmission for most forms of CMS, others, as well as neurological and muscular comorbidities, remain resistant. Taken together, the available pathological data point to physiological issues which remain to be understood in order to achieve precision medicine with efficient therapeutics for all individuals suffering from CMS.
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Affiliation(s)
- Sophie Nicole
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Yoshiteru Azuma
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Stéphanie Bauché
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Bruno Eymard
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France.,AP-HP, Hôpital Pitié-Salpétrière, 75013 Paris, France
| | - Hanns Lochmüller
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Clarke Slater
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
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41
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Finelli MJ, Aprile D, Castroflorio E, Jeans A, Moschetta M, Chessum L, Degiacomi MT, Grasegger J, Lupien-Meilleur A, Bassett A, Rossignol E, Campeau PM, Bowl MR, Benfenati F, Fassio A, Oliver PL. The epilepsy-associated protein TBC1D24 is required for normal development, survival and vesicle trafficking in mammalian neurons. Hum Mol Genet 2019; 28:584-597. [PMID: 30335140 PMCID: PMC6360273 DOI: 10.1093/hmg/ddy370] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 10/09/2018] [Indexed: 12/16/2022] Open
Abstract
Mutations in the Tre2/Bub2/Cdc16 (TBC)1 domain family member 24 (TBC1D24) gene are associated with a range of inherited neurological disorders, from drug-refractory lethal epileptic encephalopathy and DOORS syndrome (deafness, onychodystrophy, osteodystrophy, mental retardation, seizures) to non-syndromic hearing loss. TBC1D24 has been implicated in neuronal transmission and maturation, although the molecular function of the gene and the cause of the apparently complex disease spectrum remain unclear. Importantly, heterozygous TBC1D24 mutation carriers have also been reported with seizures, suggesting that haploinsufficiency for TBC1D24 is significant clinically. Here we have systematically investigated an allelic series of disease-associated mutations in neurons alongside a new mouse model to investigate the consequences of TBC1D24 haploinsufficiency to mammalian neurodevelopment and synaptic physiology. The cellular studies reveal that disease-causing mutations that disrupt either of the conserved protein domains in TBC1D24 are implicated in neuronal development and survival and are likely acting as loss-of-function alleles. We then further investigated TBC1D24 haploinsufficiency in vivo and demonstrate that TBC1D24 is also crucial for normal presynaptic function: genetic disruption of Tbc1d24 expression in the mouse leads to an impairment of endocytosis and an enlarged endosomal compartment in neurons with a decrease in spontaneous neurotransmission. These data reveal the essential role for TBC1D24 at the mammalian synapse and help to define common synaptic mechanisms that could underlie the varied effects of TBC1D24 mutations in neurological disease.
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Affiliation(s)
- Mattéa J Finelli
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, UK
| | - Davide Aprile
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Enrico Castroflorio
- Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 9, Genoa, Italy
| | - Alexander Jeans
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, UK
| | - Matteo Moschetta
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 9, Genoa, Italy
| | | | | | - Julia Grasegger
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, UK
| | - Alexis Lupien-Meilleur
- CHU Ste-Justine, Departments of Neurosciences and Pediatrics, Université de Montréal, Montreal, QC, Canada
| | - Andrew Bassett
- Cellular Operations, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Elsa Rossignol
- CHU Ste-Justine, Departments of Neurosciences and Pediatrics, Université de Montréal, Montreal, QC, Canada
| | - Philippe M Campeau
- CHU Ste-Justine, Departments of Neurosciences and Pediatrics, Université de Montréal, Montreal, QC, Canada
| | | | - Fabio Benfenati
- Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 9, Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, Genoa, Italy
| | - Anna Fassio
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, Genoa, Italy
| | - Peter L Oliver
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, UK.,MRC Harwell Institute, Harwell, Oxfordshire, UK
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42
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Lanoue V, Chai YJ, Brouillet JZ, Weckhuysen S, Palmer EE, Collins BM, Meunier FA. STXBP1 encephalopathy. Neurology 2019; 93:114-123. [DOI: 10.1212/wnl.0000000000007786] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/18/2019] [Indexed: 11/15/2022] Open
Abstract
De novo pathogenic variants in STXBP1 encoding syntaxin1-binding protein (STXBP1, also known as Munc18-1) lead to a range of early-onset neurocognitive conditions, most commonly early infantile epileptic encephalopathy type 4 (EIEE4, also called STXBP1 encephalopathy), a severe form of epilepsy associated with developmental delay/intellectual disability. Other neurologic features include autism spectrum disorder and movement disorders. The progression of neurologic symptoms has been reported in a few older affected individuals, with the appearance of extrapyramidal features, reminiscent of early onset parkinsonism. Understanding the pathologic process is critical to improving therapies, as currently available antiepileptic drugs have shown limited success in controlling seizures in EIEE4 and there is no precision medication approach for the other neurologic features of the disorder. Basic research shows that genetic knockout of STXBP1 or other presynaptic proteins of the exocytic machinery leads to widespread perinatal neurodegeneration. The mechanism that regulates this effect is under scrutiny but shares intriguing hallmarks with classical neurodegenerative diseases, albeit appearing early during brain development. Most critically, recent evidence has revealed that STXBP1 controls the self-replicating aggregation of α-synuclein, a presynaptic protein involved in various neurodegenerative diseases that are collectively known as synucleinopathies, including Parkinson disease. In this review, we examine the tantalizing link among STXBP1 function, EIEE, and the neurodegenerative synucleinopathies, and suggest that neural development in EIEE could be further affected by concurrent synucleinopathic mechanisms.
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Mutations in the Neuronal Vesicular SNARE VAMP2 Affect Synaptic Membrane Fusion and Impair Human Neurodevelopment. Am J Hum Genet 2019; 104:721-730. [PMID: 30929742 PMCID: PMC6451933 DOI: 10.1016/j.ajhg.2019.02.016] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 02/13/2019] [Indexed: 01/21/2023] Open
Abstract
VAMP2 encodes the vesicular SNARE protein VAMP2 (also called synaptobrevin-2). Together with its partners syntaxin-1A and synaptosomal-associated protein 25 (SNAP25), VAMP2 mediates fusion of synaptic vesicles to release neurotransmitters. VAMP2 is essential for vesicular exocytosis and activity-dependent neurotransmitter release. Here, we report five heterozygous de novo mutations in VAMP2 in unrelated individuals presenting with a neurodevelopmental disorder characterized by axial hypotonia (which had been present since birth), intellectual disability, and autistic features. In total, we identified two single-amino-acid deletions and three non-synonymous variants affecting conserved residues within the C terminus of the VAMP2 SNARE motif. Affected individuals carrying de novo non-synonymous variants involving the C-terminal region presented a more severe phenotype with additional neurological features, including central visual impairment, hyperkinetic movement disorder, and epilepsy or electroencephalography abnormalities. Reconstituted fusion involving a lipid-mixing assay indicated impairment in vesicle fusion as one of the possible associated disease mechanisms. The genetic synaptopathy caused by VAMP2 de novo mutations highlights the key roles of this gene in human brain development and function.
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44
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Nicolau S, Milone M. The Electrophysiology of Presynaptic Congenital Myasthenic Syndromes With and Without Facilitation: From Electrodiagnostic Findings to Molecular Mechanisms. Front Neurol 2019; 10:257. [PMID: 30941097 PMCID: PMC6433874 DOI: 10.3389/fneur.2019.00257] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 02/26/2019] [Indexed: 11/13/2022] Open
Abstract
Congenital myasthenic syndromes (CMS) are a group of inherited disorders of neuromuscular transmission most commonly presenting with early onset fatigable weakness, ptosis, and ophthalmoparesis. CMS are classified according to the localization of the causative molecular defect. CMS with presynaptic dysfunction can be caused by mutations in several different genes, including those involved in acetylcholine synthesis, its packaging into synaptic vesicles, vesicle docking, and release from the presynaptic nerve terminal and neuromuscular junction development and maintenance. Electrodiagnostic testing is key in distinguishing CMS from other neuromuscular disorders with similar clinical features as well as for revealing features pointing to a specific molecular diagnosis. A decremental response on low-frequency repetitive nerve stimulation (RNS) is present in most presynaptic CMS. In CMS with deficits in acetylcholine resynthesis however, a decrement may only appear after conditioning with exercise or high-frequency RNS and characteristically displays a slow recovery. Facilitation occurs in CMS caused by mutations in VAMP1, UNC13A, SYT2, AGRN, LAMA5. By contrast, facilitation is absent in the other presynaptic CMS described to date. An understanding of the underlying molecular mechanisms therefore assists the interpretation of electrodiagnostic findings in patients with suspected CMS.
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Affiliation(s)
- Stefan Nicolau
- Department of Neurology, Mayo Clinic, Rochester, MN, United States
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45
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Ugur B, Bao H, Stawarski M, Duraine LR, Zuo Z, Lin YQ, Neely GG, Macleod GT, Chapman ER, Bellen HJ. The Krebs Cycle Enzyme Isocitrate Dehydrogenase 3A Couples Mitochondrial Metabolism to Synaptic Transmission. Cell Rep 2019; 21:3794-3806. [PMID: 29281828 DOI: 10.1016/j.celrep.2017.12.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 11/10/2017] [Accepted: 12/01/2017] [Indexed: 10/18/2022] Open
Abstract
Neurotransmission is a tightly regulated Ca2+-dependent process. Upon Ca2+ influx, Synaptotagmin1 (Syt1) promotes fusion of synaptic vesicles (SVs) with the plasma membrane. This requires regulation at multiple levels, but the role of metabolites in SV release is unclear. Here, we uncover a role for isocitrate dehydrogenase 3a (idh3a), a Krebs cycle enzyme, in neurotransmission. Loss of idh3a leads to a reduction of the metabolite, alpha-ketoglutarate (αKG), causing defects in synaptic transmission similar to the loss of syt1. Supplementing idh3a flies with αKG suppresses these defects through an ATP or neurotransmitter-independent mechanism. Indeed, αKG, but not glutamate, enhances Syt1-dependent fusion in a reconstitution assay. αKG promotes interaction between the C2-domains of Syt1 and phospholipids. The data reveal conserved metabolic regulation of synaptic transmission via αKG. Our studies provide a synaptic role for αKG, a metabolite that has been proposed as a treatment for aging and neurodegenerative disorders.
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Affiliation(s)
- Berrak Ugur
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Huan Bao
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705, USA; Howard Hughes Medical Institute, University of Wisconsin, Madison, WI 53705, USA
| | - Michal Stawarski
- Department of Biological Sciences and Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Lita R Duraine
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zhongyuan Zuo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yong Qi Lin
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
| | - G Gregory Neely
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
| | - Gregory T Macleod
- Department of Biological Sciences and Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Edwin R Chapman
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705, USA; Howard Hughes Medical Institute, University of Wisconsin, Madison, WI 53705, USA
| | - Hugo J Bellen
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA.
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Abstract
OBJECTIVES Congenital myasthenic syndromes (CMSs) are a genotypically and phenotypically heterogeneous group of neuromuscular disorders, which have in common an impaired neuromuscular transmission. Since the field of CMSs is steadily expanding, the present review aimed at summarizing and discussing current knowledge and recent advances concerning the etiology, clinical presentation, diagnosis, and treatment of CMSs. METHODS Systematic literature review. RESULTS Currently, mutations in 32 genes are made responsible for autosomal dominant or autosomal recessive CMSs. These mutations concern 8 presynaptic, 4 synaptic, 15 post-synaptic, and 5 glycosilation proteins. These proteins function as ion-channels, enzymes, or structural, signalling, sensor, or transporter proteins. The most common causative genes are CHAT, COLQ, RAPSN, CHRNE, DOK7, and GFPT1. Phenotypically, these mutations manifest as abnormal fatigability or permanent or fluctuating weakness of extra-ocular, facial, bulbar, axial, respiratory, or limb muscles, hypotonia, or developmental delay. Cognitive disability, dysmorphism, neuropathy, or epilepsy are rare. Low- or high-frequency repetitive nerve stimulation may show an abnormal increment or decrement, and SF-EMG an increased jitter or blockings. Most CMSs respond favourably to acetylcholine-esterase inhibitors, 3,4-diamino-pyridine, salbutamol, albuterol, ephedrine, fluoxetine, or atracurium. CONCLUSIONS CMSs are an increasingly recognised group of genetically transmitted defects, which usually respond favorably to drugs enhancing the neuromuscular transmission. CMSs need to be differentiated from neuromuscular disorders due to muscle or nerve dysfunction.
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Affiliation(s)
- Josef Finsterer
- Krankenanstalt Rudolfstiftung, Messerli Institute, Veterinary University of Vienna, Postfach 20, 1180, Vienna, Austria.
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47
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Targeted therapies for congenital myasthenic syndromes: systematic review and steps towards a treatabolome. Emerg Top Life Sci 2019; 3:19-37. [PMID: 30931400 PMCID: PMC6436731 DOI: 10.1042/etls20180100] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Despite recent scientific advances, most rare genetic diseases — including most neuromuscular diseases — do not currently have curative gene-based therapies available. However, in some cases, such as vitamin, cofactor or enzyme deficiencies, channelopathies and disorders of the neuromuscular junction, a confirmed genetic diagnosis provides guidance on treatment, with drugs available that may significantly alter the disease course, improve functional ability and extend life expectancy. Nevertheless, many treatable patients remain undiagnosed or do not receive treatment even after genetic diagnosis. The growth of computer-aided genetic analysis systems that enable clinicians to diagnose their undiagnosed patients has not yet been matched by genetics-based decision-support systems for treatment guidance. Generating a ‘treatabolome’ of treatable variants and the evidence for the treatment has the potential to increase treatment rates for treatable conditions. Here, we use the congenital myasthenic syndromes (CMS), a group of clinically and genetically heterogeneous but frequently treatable neuromuscular conditions, to illustrate the steps in the creation of a treatabolome for rare inherited diseases. We perform a systematic review of the evidence for pharmacological treatment of each CMS type, gathering evidence from 207 studies of over 1000 patients and stratifying by genetic defect, as treatment varies depending on the underlying cause. We assess the strength and quality of the evidence and create a dataset that provides the foundation for a computer-aided system to enable clinicians to gain easier access to information about treatable variants and the evidence they need to consider.
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48
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Karmakar S, Sharma LG, Roy A, Patel A, Pandey LM. Neuronal SNARE complex: A protein folding system with intricate protein-protein interactions, and its common neuropathological hallmark, SNAP25. Neurochem Int 2018; 122:196-207. [PMID: 30517887 DOI: 10.1016/j.neuint.2018.12.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 11/08/2018] [Accepted: 12/01/2018] [Indexed: 12/26/2022]
Abstract
SNARE (Soluble NSF(N-ethylmaleimide-sensitive factor) Attachment Receptor) complex is a trimeric supramolecular organization of SNAP25, syntaxin, and VAMP which mediates fusion of synaptic vesicles with the presynaptic plasma membrane. The functioning of this entire protein assembly is dependent on its tetrahelical coiled coil structure alongside its interaction with a large spectrum of regulatory proteins like synaptotagmin, complexin, intersectin, etc. Defects arising in SNARE complex assembly due to mutations or faulty post-translational modifications are associated to severe synaptopathies like Schizophrenia and also proteopathies like Alzheimer's disease. The review primarily focuses on SNAP25, which is the prime contributor in the complex assembly. It is conceptualized that the network of protein interactions of this helical protein assists as a chaperoning system for attaining functional structure. Additionally, the innate disordered nature of SNAP25 and its amyloidogenic propensities have been highlighted employing computational methods. The intrinsic nature of SNAP25 is anticipated to form higher-order aggregates due to its cysteine rich domain, which is also a target for several post-translational modifications. Furthermore, the aberrations in the structure and expression profile of the protein display common patterns in the pathogenesis of a diverse synaptopathies and proteopathies. This work of SNARE literature aims to provide a new comprehensive outlook and research directions towards SNARE complex and presents SNAP25 as a common neuropathological hallmark which can be a diagnostic or therapeutic target.
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Affiliation(s)
- Srijeeb Karmakar
- Bio-Interface & Environmental Engineering Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam, 781039, India.
| | - Laipubam Gayatri Sharma
- Bio-Interface & Environmental Engineering Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam, 781039, India.
| | - Abhishek Roy
- Bio-Interface & Environmental Engineering Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam, 781039, India.
| | - Anjali Patel
- Bio-Interface & Environmental Engineering Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam, 781039, India.
| | - Lalit Mohan Pandey
- Bio-Interface & Environmental Engineering Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam, 781039, India.
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49
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Magalhães-Gomes MPS, Motta-Santos D, Schetino LPL, Andrade JN, Bastos CP, Guimarães DAS, Vaughan SK, Martinelli PM, Guatimosim S, Pereira GS, Coimbra CC, Prado VF, Prado MAM, Valdez G, Guatimosim C. Fast and slow-twitching muscles are differentially affected by reduced cholinergic transmission in mice deficient for VAChT: A mouse model for congenital myasthenia. Neurochem Int 2018; 120:1-12. [PMID: 30003945 PMCID: PMC6421860 DOI: 10.1016/j.neuint.2018.07.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 06/27/2018] [Accepted: 07/07/2018] [Indexed: 12/15/2022]
Abstract
Congenital myasthenic syndromes (CMS) result from reduced cholinergic transmission at neuromuscular junctions (NMJs). While the etiology of CMS varies, the disease is characterized by muscle weakness. To date, it remains unknown if CMS causes long-term and irreversible changes to skeletal muscles. In this study, we examined skeletal muscles in a mouse line with reduced expression of Vesicular Acetylcholine Transporter (VAChT, mouse line herein called VAChT-KDHOM). We examined this mouse line for several reasons. First, VAChT plays a central function in loading acetylcholine (ACh) into synaptic vesicles and releasing it at NMJs, in addition to other cholinergic nerve endings. Second, loss of function mutations in VAChT causes myasthenia in humans. Importantly, VAChT-KDHOM present with reduced ACh and muscle weakness, resembling CMS. We evaluated the morphology, fiber type (myosin heavy chain isoforms), and expression of muscle-related genes in the extensor digitorum longus (EDL) and soleus muscles. This analysis revealed that while muscle fibers atrophy in the EDL, they hypertrophy in the soleus muscle of VAChT-KDHOM mice. Along with these cellular changes, skeletal muscles exhibit altered levels of markers for myogenesis (Pax-7, Myogenin, and MyoD), oxidative metabolism (PGC1-α and MTND1), and protein degradation (Atrogin1 and MuRF1) in VAChT-KDHOM mice. Importantly, we demonstrate that deleterious changes in skeletal muscles and motor deficits can be partially reversed following the administration of the cholinesterase inhibitor, pyridostigmine in VAChT-KDHOM mice. These findings reveal that fast and slow type muscles differentially respond to cholinergic deficits. Additionally, this study shows that the adverse effects of cholinergic transmission, as in the case of CMS, on fast and slow type skeletal muscles are reversible.
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Affiliation(s)
| | - Daisy Motta-Santos
- Departamento de Fisiologia e Biofísica, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil; Departamento de Esportes, EEFFTO, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Luana P L Schetino
- Departamento de Morfologia, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Jéssica N Andrade
- Departamento de Morfologia, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Cristiane P Bastos
- Departamento de Fisiologia e Biofísica, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | | | - Sydney K Vaughan
- Virginia Tech Carilion Research Institute, Roanoke, VA, USA; Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, VA, USA
| | - Patrícia M Martinelli
- Departamento de Morfologia, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Silvia Guatimosim
- Departamento de Fisiologia e Biofísica, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Grace S Pereira
- Departamento de Fisiologia e Biofísica, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Candido C Coimbra
- Departamento de Fisiologia e Biofísica, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Vânia F Prado
- Robarts Research Institute and Department of Physiology and Pharmacology and Anatomy & Cell Biology, University of Western Ontario, London, ON, Canada
| | - Marco A M Prado
- Robarts Research Institute and Department of Physiology and Pharmacology and Anatomy & Cell Biology, University of Western Ontario, London, ON, Canada
| | - Gregorio Valdez
- Virginia Tech Carilion Research Institute, Roanoke, VA, USA; Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA
| | - Cristina Guatimosim
- Departamento de Morfologia, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
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50
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Cortès-Saladelafont E, Lipstein N, García-Cazorla À. Presynaptic disorders: a clinical and pathophysiological approach focused on the synaptic vesicle. J Inherit Metab Dis 2018; 41:1131-1145. [PMID: 30022305 DOI: 10.1007/s10545-018-0230-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 06/23/2018] [Accepted: 07/02/2018] [Indexed: 12/12/2022]
Abstract
The aim of this report is to present a tentative clinical and pathophysiological approach to diseases affecting the neuronal presynaptic terminal, with a major focus on synaptic vesicles (SVs). Diseases are classified depending on which step of the neurobiology of the SV is predominantly affected: (1) biogenesis of vesicle precursors in the neuronal soma; (2) transport along the axon; (3) vesicle cycle at the presynaptic terminal (exocytosis-endocytosis cycle, with the main purpose of neurotransmitter release). Given that SVs have been defined as individual organelles, we highlight the link between the biological processes disturbed by genetic mutations and the clinical presentation of these disorders. The great majority of diseases may present as epileptic encephalopathies, intellectual disability (syndromic or nonsyndromic) with/without autism spectrum disorder (and other neuropsychiatric symptoms), and movement disorders. These symptoms may overlap and present in patients as a combination of clinical signs that results in the spectrum of the synaptopathies. A small number of diseases may also exhibit neuromuscular signs. In general, SV disorders tend to be severe, early encephalopathies that interfere with neurodevelopment. As a consequence, developmental delay and intellectual disability are constant in almost all the defects described. Considering that some of these diseases might mimic other neurometabolic conditions (and in particular treatable disorders), an initial extensive metabolic workup should always be considered. Further knowledge into pathophysiological mechanisms and biomarkers, as well as descriptions of new presynaptic disorders, will probably take place in the near future.
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Affiliation(s)
- Elisenda Cortès-Saladelafont
- Department of Neurology, Neurometabolic Unit and Synaptic Metabolism Laboratory, Institut Pediàtric de Recerca and CIBERER, ISCIII, Hospital Sant Joan de Déu, Passeig Sant Joan de Déu, 2, 08950, Esplugues, Barcelona, Spain
| | - Noa Lipstein
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Àngels García-Cazorla
- Department of Neurology, Neurometabolic Unit and Synaptic Metabolism Laboratory, Institut Pediàtric de Recerca and CIBERER, ISCIII, Hospital Sant Joan de Déu, Passeig Sant Joan de Déu, 2, 08950, Esplugues, Barcelona, Spain.
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