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Muscarinic Receptors in Developmental Axonal Competition at the Neuromuscular Junction. Mol Neurobiol 2023; 60:1580-1593. [PMID: 36526930 PMCID: PMC9899176 DOI: 10.1007/s12035-022-03154-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 11/29/2022] [Indexed: 12/23/2022]
Abstract
In recent years, we have studied by immunohistochemistry, intracellular recording, and western blotting the role of the muscarinic acetylcholine receptors (mAChRs; M1, M2, and M4 subtypes) in the mammalian neuromuscular junction (NMJ) during development and in the adult. Here, we evaluate our published data to emphasize the mAChRs' relevance in developmental synaptic elimination and their crosstalk with other metabotropic receptors, downstream kinases, and voltage-gated calcium channels (VGCCs). The presence of mAChRs in the presynaptic membrane of motor nerve terminals allows an autocrine mechanism in which the secreted acetylcholine influences the cell itself in feedback. mAChR subtypes are coupled to different downstream pathways, so their feedback can move in a broad range between positive and negative. Moreover, mAChRs allow direct activity-dependent interaction through ACh release between the multiple competing axons during development. Additional regulation from pre- and postsynaptic sites (including neurotrophic retrograde control), the agonistic and antagonistic contributions of adenosine receptors (AR; A1 and A2A), and the tropomyosin-related kinase B receptor (TrkB) cooperate with mAChRs in the axonal competitive interactions which lead to supernumerary synapse elimination that achieves the optimized monoinnervation of musculoskeletal cells. The metabotropic receptor-driven balance between downstream PKA and PKC activities, coupled to developmentally regulated VGCC, explains much of how nerve terminals with different activities finally progress to their withdrawal or strengthening.
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2
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Laszlo ZI, Hindley N, Sanchez Avila A, Kline RA, Eaton SL, Lamont DJ, Smith C, Spires-Jones TL, Wishart TM, Henstridge CM. Synaptic proteomics reveal distinct molecular signatures of cognitive change and C9ORF72 repeat expansion in the human ALS cortex. Acta Neuropathol Commun 2022; 10:156. [DOI: 10.1186/s40478-022-01455-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 09/30/2022] [Indexed: 11/10/2022] Open
Abstract
AbstractIncreasing evidence suggests synaptic dysfunction is a central and possibly triggering factor in Amyotrophic Lateral Sclerosis (ALS). Despite this, we still know very little about the molecular profile of an ALS synapse. To address this gap, we designed a synaptic proteomics experiment to perform an unbiased assessment of the synaptic proteome in the ALS brain. We isolated synaptoneurosomes from fresh-frozen post-mortem human cortex (11 controls and 18 ALS) and stratified the ALS group based on cognitive profile (Edinburgh Cognitive and Behavioural ALS Screen (ECAS score)) and presence of a C9ORF72 hexanucleotide repeat expansion (C9ORF72-RE). This allowed us to assess regional differences and the impact of phenotype and genotype on the synaptic proteome, using Tandem Mass Tagging-based proteomics. We identified over 6000 proteins in our synaptoneurosomes and using robust bioinformatics analysis we validated the strong enrichment of synapses. We found more than 30 ALS-associated proteins in synaptoneurosomes, including TDP-43, FUS, SOD1 and C9ORF72. We identified almost 500 proteins with altered expression levels in ALS, with region-specific changes highlighting proteins and pathways with intriguing links to neurophysiology and pathology. Stratifying the ALS cohort by cognitive status revealed almost 150 specific alterations in cognitively impaired ALS synaptic preparations. Stratifying by C9ORF72-RE status revealed 330 protein alterations in the C9ORF72-RE +ve group, with KEGG pathway analysis highlighting strong enrichment for postsynaptic dysfunction, related to glutamatergic receptor signalling. We have validated some of these changes by western blot and at a single synapse level using array tomography imaging. In summary, we have generated the first unbiased map of the human ALS synaptic proteome, revealing novel insight into this key compartment in ALS pathophysiology and highlighting the influence of cognitive decline and C9ORF72-RE on synaptic composition.
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3
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Personius KE, Siebert D, Koch DW, Udin SB. Blockage of neuromuscular glutamate receptors impairs reinnervation following nerve crush in adult mice. Front Cell Neurosci 2022; 16:1000218. [PMID: 36212695 PMCID: PMC9535682 DOI: 10.3389/fncel.2022.1000218] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 09/02/2022] [Indexed: 11/29/2022] Open
Abstract
Motor axons in peripheral nerves are capable of regeneration following injury. However, complete recovery of motor function is rare, particularly when reinnervation is delayed. We have previously found that glutamate receptors play a crucial role in the successful innervation of muscle during mouse development. In particular, blocking N-methyl-D-aspartate (NMDA) receptor activity delays the normal elimination of excess innervation of each neuromuscular junction. Here, we use behavioral, immunohistochemical, electrophysiological, and calcium imaging methods to test whether glutamate receptors play a similar role in the transition from polyneuronal to mono-innervation and in recovery of function following peripheral nerve injury in mature muscle.
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Affiliation(s)
- Kirkwood E. Personius
- Program in Neuroscience, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, United States
- Department of Rehabilitation Science, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
- *Correspondence: Kirkwood E. Personius,
| | - Danielle Siebert
- Program in Neuroscience, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, United States
| | - Dennis W. Koch
- Department of Kinesiology, Canisius College, Buffalo, NY, United States
| | - Susan B. Udin
- Program in Neuroscience, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, United States
- Department of Physiology and Biophysics, School of Medicine and Biomedical Sciences, Buffalo, NY, United States
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4
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Davis LA, Fogarty MJ, Brown A, Sieck GC. Structure and Function of the Mammalian Neuromuscular Junction. Compr Physiol 2022; 12:3731-3766. [PMID: 35950651 PMCID: PMC10461538 DOI: 10.1002/cphy.c210022] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The mammalian neuromuscular junction (NMJ) comprises a presynaptic terminal, a postsynaptic receptor region on the muscle fiber (endplate), and the perisynaptic (terminal) Schwann cell. As with any synapse, the purpose of the NMJ is to transmit signals from the nervous system to muscle fibers. This neural control of muscle fibers is organized as motor units, which display distinct structural and functional phenotypes including differences in pre- and postsynaptic elements of NMJs. Motor units vary considerably in the frequency of their activation (both motor neuron discharge rate and duration/duty cycle), force generation, and susceptibility to fatigue. For earlier and more frequently recruited motor units, the structure and function of the activated NMJs must have high fidelity to ensure consistent activation and continued contractile response to sustain vital motor behaviors (e.g., breathing and postural balance). Similarly, for higher force less frequent behaviors (e.g., coughing and jumping), the structure and function of recruited NMJs must ensure short-term reliable activation but not activation sustained for a prolonged period in which fatigue may occur. The NMJ is highly plastic, changing structurally and functionally throughout the life span from embryonic development to old age. The NMJ also changes under pathological conditions including acute and chronic disease. Such neuroplasticity often varies across motor unit types. © 2022 American Physiological Society. Compr Physiol 12:1-36, 2022.
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Affiliation(s)
- Leah A. Davis
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Matthew J. Fogarty
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Alyssa Brown
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Gary C. Sieck
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
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5
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Woo E, Sansing LH, Arnsten AFT, Datta D. Chronic Stress Weakens Connectivity in the Prefrontal Cortex: Architectural and Molecular Changes. CHRONIC STRESS 2021; 5:24705470211029254. [PMID: 34485797 PMCID: PMC8408896 DOI: 10.1177/24705470211029254] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 06/14/2021] [Indexed: 12/26/2022]
Abstract
Chronic exposure to uncontrollable stress causes loss of spines and dendrites in the prefrontal cortex (PFC), a recently evolved brain region that provides top-down regulation of thought, action, and emotion. PFC neurons generate top-down goals through recurrent excitatory connections on spines. This persistent firing is the foundation for higher cognition, including working memory, and abstract thought. However, exposure to acute uncontrollable stress drives high levels of catecholamine release in the PFC, which activates feedforward calcium-cAMP signaling pathways to open nearby potassium channels, rapidly weakening synaptic connectivity to reduce persistent firing. Chronic stress exposures can further exacerbate these signaling events leading to loss of spines and resulting in marked cognitive impairment. In this review, we discuss how stress signaling mechanisms can lead to spine loss, including changes to BDNF-mTORC1 signaling, calcium homeostasis, actin dynamics, and mitochondrial actions that engage glial removal of spines through inflammatory signaling. Stress signaling events may be amplified in PFC spines due to cAMP magnification of internal calcium release. As PFC dendritic spine loss is a feature of many cognitive disorders, understanding how stress affects the structure and function of the PFC will help to inform strategies for treatment and prevention.
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Affiliation(s)
- Elizabeth Woo
- Department of Neuroscience, Yale Medical School, New Haven, CT, USA.,Department of Neurology, Yale Medical School, New Haven, CT, USA
| | - Lauren H Sansing
- Department of Neurology, Yale Medical School, New Haven, CT, USA
| | - Amy F T Arnsten
- Department of Neuroscience, Yale Medical School, New Haven, CT, USA
| | - Dibyadeep Datta
- Department of Neuroscience, Yale Medical School, New Haven, CT, USA
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6
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James OG, Selvaraj BT, Magnani D, Burr K, Connick P, Barton SK, Vasistha NA, Hampton DW, Story D, Smigiel R, Ploski R, Brophy PJ, Ffrench-Constant C, Lyons DA, Chandran S. iPSC-derived myelinoids to study myelin biology of humans. Dev Cell 2021; 56:1346-1358.e6. [PMID: 33945785 PMCID: PMC8098746 DOI: 10.1016/j.devcel.2021.04.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 01/20/2021] [Accepted: 04/06/2021] [Indexed: 01/03/2023]
Abstract
Myelination is essential for central nervous system (CNS) formation, health, and function. Emerging evidence of oligodendrocyte heterogeneity in health and disease and divergent CNS gene expression profiles between mice and humans supports the development of experimentally tractable human myelination systems. Here, we developed human iPSC-derived myelinating organoids ("myelinoids") and quantitative tools to study myelination from oligodendrogenesis through to compact myelin formation and myelinated axon organization. Using patient-derived cells, we modeled a monogenetic disease of myelinated axons (Nfasc155 deficiency), recapitulating impaired paranodal axo-glial junction formation. We also validated the use of myelinoids for pharmacological assessment of myelination-both at the level of individual oligodendrocytes and globally across whole myelinoids-and demonstrated reduced myelination in response to suppressed synaptic vesicle release. Our study provides a platform to investigate human myelin development, disease, and adaptive myelination.
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Affiliation(s)
- Owen G James
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK; Anne Rowling Regenerative Neurology Clinic, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Bhuvaneish T Selvaraj
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Dario Magnani
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Karen Burr
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Peter Connick
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Anne Rowling Regenerative Neurology Clinic, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Samantha K Barton
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK; Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Navneet A Vasistha
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK; Biotech Research and Innovation Centre, Copenhagen N 2200, Denmark
| | - David W Hampton
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK
| | - David Story
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Robert Smigiel
- Department of Pediatrics and Rare Disorders, Wroclaw Medical University, Wrocław 51-618, Poland
| | - Rafal Ploski
- Department of Medical Genetics, Medical University of Warsaw, Warsaw 02-106, Poland
| | - Peter J Brophy
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | | | - David A Lyons
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Siddharthan Chandran
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK; Anne Rowling Regenerative Neurology Clinic, University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Brain Development and Repair, inStem, Bangalore 560065, India.
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7
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Wang M, Kleele T, Xiao Y, Plucinska G, Avramopoulos P, Engelhardt S, Schwab MH, Kneussel M, Czopka T, Sherman DL, Brophy PJ, Misgeld T, Brill MS. Completion of neuronal remodeling prompts myelination along developing motor axon branches. J Cell Biol 2021; 220:e201911114. [PMID: 33538762 PMCID: PMC7868780 DOI: 10.1083/jcb.201911114] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 11/20/2020] [Accepted: 01/04/2021] [Indexed: 12/20/2022] Open
Abstract
Neuronal remodeling and myelination are two fundamental processes during neurodevelopment. How they influence each other remains largely unknown, even though their coordinated execution is critical for circuit function and often disrupted in neuropsychiatric disorders. It is unclear whether myelination stabilizes axon branches during remodeling or whether ongoing remodeling delays myelination. By modulating synaptic transmission, cytoskeletal dynamics, and axonal transport in mouse motor axons, we show that local axon remodeling delays myelination onset and node formation. Conversely, glial differentiation does not determine the outcome of axon remodeling. Delayed myelination is not due to a limited supply of structural components of the axon-glial unit but rather is triggered by increased transport of signaling factors that initiate myelination, such as neuregulin. Further, transport of promyelinating signals is regulated via local cytoskeletal maturation related to activity-dependent competition. Our study reveals an axon branch-specific fine-tuning mechanism that locally coordinates axon remodeling and myelination.
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Affiliation(s)
- Mengzhe Wang
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
| | - Tatjana Kleele
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
| | - Yan Xiao
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
| | - Gabriela Plucinska
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
| | - Petros Avramopoulos
- Institute of Pharmacology and Toxicology, Technische Universität München, Munich, Germany
- German Center for Cardiovascular Research (DZHK), partner site Munich Heart Alliance, Munich, Germany
| | - Stefan Engelhardt
- Institute of Pharmacology and Toxicology, Technische Universität München, Munich, Germany
- German Center for Cardiovascular Research (DZHK), partner site Munich Heart Alliance, Munich, Germany
| | - Markus H. Schwab
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Matthias Kneussel
- University Medical Center Hamburg-Eppendorf, Center for Molecular Neurobiology (ZMNH), Institute for Molecular Neurogenetics, Hamburg, Germany
| | - Tim Czopka
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK
- Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
| | - Diane L. Sherman
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Peter J. Brophy
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Thomas Misgeld
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
- Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
| | - Monika S. Brill
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
- Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
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8
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Momenzadeh S, Zamani S, Dehghan F, Barreiro C, Jami MS. Comparative proteome analyses highlight several exercise-like responses of mouse sciatic nerve after IP injection of irisin. Eur J Neurosci 2021; 53:3263-3278. [PMID: 33759230 DOI: 10.1111/ejn.15202] [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: 12/12/2020] [Revised: 02/19/2021] [Accepted: 03/12/2021] [Indexed: 12/16/2022]
Abstract
Many beneficial effects of exercise on the nervous system are mediated by hormone (growth factor)/receptor signaling. Considering the accumulating evidence on the similarity of some beneficial effects, irisin can be a proposed effector of exercise; however, the mechanism underlying these effects remains largely unknown. More evidence on the mechanism of action might reveal its potential as a treatment strategy to substitute exercise recovery protocols for nerve injuries in physically disabled patients. To evaluate the underlying mechanism of irisin involvement in nerve adaptation and exerting beneficial effects, we studied the proteome profile alteration of mouse sciatic nerve after irisin administration. We also compared it with two 8-week protocols of resistance exercise and endurance exercise. The results indicate that irisin contributes to the regulation of nerve metabolism via overexpression of Ckm and ATP5j2 proteins. Irisin administration may improve sciatic nerve function by maintaining the architecture, enhancing axonal transport, and promoting synapse plasticity through increased structural and regulatory proteins and NO production. We also showed that irisin has the potential to induce neurotrophic support on the sciatic nerve by maintaining cell redox homeostasis, and responses to oxidative stress via the upregulation of disulfide-isomerase and superoxide dismutase enzymes. Comparing with exercise groups, these effects are somewhat exercise-like responses. These data suggest that irisin can be a promising therapeutic candidate for specific targeting of defects in peripheral neuropathies and nerve injuries as an alternative for physical therapy.
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Affiliation(s)
- Sedigheh Momenzadeh
- Department of Medical Biotechnology, School of Advanced Technologies, Shahrekord University of Medical Sciences, Shahrekord, Iran.,Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Saeed Zamani
- Department of Anatomical Sciences, School of Medicine, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Fariba Dehghan
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Carlos Barreiro
- 5 INBIOTEC (Instituto de Biotecnología de León), León, Spain.,Departamento de Biología Molecular, Universidad de León, Ponferrada, Spain
| | - Mohammad-Saeid Jami
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran.,Department of Neurology, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, CA, USA
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9
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Raiders S, Han T, Scott-Hewitt N, Kucenas S, Lew D, Logan MA, Singhvi A. Engulfed by Glia: Glial Pruning in Development, Function, and Injury across Species. J Neurosci 2021; 41:823-833. [PMID: 33468571 PMCID: PMC7880271 DOI: 10.1523/jneurosci.1660-20.2020] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/20/2020] [Accepted: 10/26/2020] [Indexed: 02/07/2023] Open
Abstract
Phagocytic activity of glial cells is essential for proper nervous system sculpting, maintenance of circuitry, and long-term brain health. Glial engulfment of apoptotic cells and superfluous connections ensures that neuronal connections are appropriately refined, while clearance of damaged projections and neurotoxic proteins in the mature brain protects against inflammatory insults. Comparative work across species and cell types in recent years highlights the striking conservation of pathways that govern glial engulfment. Many signaling cascades used during developmental pruning are re-employed in the mature brain to "fine tune" synaptic architecture and even clear neuronal debris following traumatic events. Moreover, the neuron-glia signaling events required to trigger and perform phagocytic responses are impressively conserved between invertebrates and vertebrates. This review offers a compare-and-contrast portrayal of recent findings that underscore the value of investigating glial engulfment mechanisms in a wide range of species and contexts.
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Affiliation(s)
- Stephan Raiders
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, Washington 98195
| | - Taeho Han
- UCSF Weill Institute for Neurosciences, University of California San Francisco, San Francisco, California 94158
| | - Nicole Scott-Hewitt
- F.M. Kirby Center for Neurobiology, Boston Children's Hospital, Boston, Massachusetts 02115
- Stanley Center for Psychiatric Research, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts 02142
| | - Sarah Kucenas
- Department of Biology, University of Virginia, Charlottesville, Virginia 22904
| | - Deborah Lew
- Department of Biological Sciences, Fordham University, Bronx, New York 10458
| | - Mary A Logan
- Jungers Center, Department of Neurology, Oregon Health and Science University, Portland, Oregon 97239
| | - Aakanksha Singhvi
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, Washington 98195
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10
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Rodríguez Cruz PM, Cossins J, Beeson D, Vincent A. The Neuromuscular Junction in Health and Disease: Molecular Mechanisms Governing Synaptic Formation and Homeostasis. Front Mol Neurosci 2020; 13:610964. [PMID: 33343299 PMCID: PMC7744297 DOI: 10.3389/fnmol.2020.610964] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 10/30/2020] [Indexed: 12/28/2022] Open
Abstract
The neuromuscular junction (NMJ) is a highly specialized synapse between a motor neuron nerve terminal and its muscle fiber that are responsible for converting electrical impulses generated by the motor neuron into electrical activity in the muscle fibers. On arrival of the motor nerve action potential, calcium enters the presynaptic terminal, which leads to the release of the neurotransmitter acetylcholine (ACh). ACh crosses the synaptic gap and binds to ACh receptors (AChRs) tightly clustered on the surface of the muscle fiber; this leads to the endplate potential which initiates the muscle action potential that results in muscle contraction. This is a simplified version of the events in neuromuscular transmission that take place within milliseconds, and are dependent on a tiny but highly structured NMJ. Much of this review is devoted to describing in more detail the development, maturation, maintenance and regeneration of the NMJ, but first we describe briefly the most important molecules involved and the conditions that affect their numbers and function. Most important clinically worldwide, are myasthenia gravis (MG), the Lambert-Eaton myasthenic syndrome (LEMS) and congenital myasthenic syndromes (CMS), each of which causes specific molecular defects. In addition, we mention the neurotoxins from bacteria, snakes and many other species that interfere with neuromuscular transmission and cause potentially fatal diseases, but have also provided useful probes for investigating neuromuscular transmission. There are also changes in NMJ structure and function in motor neuron disease, spinal muscle atrophy and sarcopenia that are likely to be secondary but might provide treatment targets. The NMJ is one of the best studied and most disease-prone synapses in the nervous system and it is amenable to in vivo and ex vivo investigation and to systemic therapies that can help restore normal function.
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Affiliation(s)
- Pedro M. Rodríguez Cruz
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - Judith Cossins
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
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11
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Kunisawa K, Hatanaka N, Shimizu T, Kobayashi K, Osanai Y, Mouri A, Shi Q, Bhat MA, Nambu A, Ikenaka K. Focal loss of the paranodal domain protein Neurofascin155 in the internal capsule impairs cortically induced muscle activity in vivo. Mol Brain 2020; 13:159. [PMID: 33228720 PMCID: PMC7685608 DOI: 10.1186/s13041-020-00698-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 11/13/2020] [Indexed: 11/12/2022] Open
Abstract
Paranodal axoglial junctions are essential for rapid nerve conduction and the organization of axonal domains in myelinated axons. Neurofascin155 (Nfasc155) is a glial cell adhesion molecule that is also required for the assembly of these domains. Previous studies have demonstrated that general ablation of Nfasc155 disorganizes these domains, reduces conduction velocity, and disrupts motor behaviors. Multiple sclerosis (MS), a typical disorder of demyelination in the central nervous system, is reported to have autoantibody to Nfasc. However, the impact of focal loss of Nfasc155, which may occur in MS patients, remains unclear. Here, we examined whether restricted focal loss of Nfasc155 affects the electrophysiological properties of the motor system in vivo. Adeno-associated virus type5 (AAV5) harboring EGFP-2A-Cre was injected into the glial-enriched internal capsule of floxed-Neurofascin (NfascFlox/Flox) mice to focally disrupt paranodal junctions in the cortico-fugal fibers from the motor cortex to the spinal cord. Electromyograms (EMGs) of the triceps brachii muscles in response to electrical stimulation of the motor cortex were successively examined in these awake mice. EMG analysis showed significant delay in the onset and peak latencies after AAV injection compared to control (Nfasc+/+) mice. Moreover, EMG half-widths were increased, and EMG amplitudes were gradually decreased by 13 weeks. Similar EMG changes have been reported in MS patients. These findings provide physiological evidence that motor outputs are obstructed by focal ablation of paranodal junctions in myelinated axons. Our findings may open a new path toward development of a novel biomarker for an early phase of human MS, as Nfasc155 detects microstructural changes in the paranodal junction.
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Affiliation(s)
- Kazuo Kunisawa
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, 444-8787, Japan
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan
- Department of Regulatory Science for Evaluation and Development of Pharmaceuticals and Devices, Fujita Health University Graduate School of Health Sciences, Toyoake, 470-1192, Japan
| | - Nobuhiko Hatanaka
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan.
- Division of System Neurophysiology, National Institute for Physiological Sciences, 38 Nishigonaka, Myodaiji, Okazaki, 444-8585, Japan.
| | - Takeshi Shimizu
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, 444-8787, Japan
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan
- Department of Neurophysiology and Brain Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8601, Japan
| | - Kenta Kobayashi
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan
- Section of Viral Vector Development, National Institute for Physiological Sciences, Okazaki, 444-8585, Japan
| | - Yasuyuki Osanai
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, 444-8787, Japan
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan
| | - Akihiro Mouri
- Department of Regulatory Science for Evaluation and Development of Pharmaceuticals and Devices, Fujita Health University Graduate School of Health Sciences, Toyoake, 470-1192, Japan
| | - Qian Shi
- Department of Cellular and Integrative Physiology, School of Medicine, University of Texas Health Science Center, San Antonio, 78229-3900, USA
| | - Manzoor A Bhat
- Department of Cellular and Integrative Physiology, School of Medicine, University of Texas Health Science Center, San Antonio, 78229-3900, USA
| | - Atsushi Nambu
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan
- Division of System Neurophysiology, National Institute for Physiological Sciences, 38 Nishigonaka, Myodaiji, Okazaki, 444-8585, Japan
| | - Kazuhiro Ikenaka
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, 444-8787, Japan
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan
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12
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Fu XQ, Peng J, Wang AH, Luo ZG. Tumor necrosis factor alpha mediates neuromuscular synapse elimination. Cell Discov 2020; 6:9. [PMID: 32140252 PMCID: PMC7051980 DOI: 10.1038/s41421-020-0143-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 01/03/2020] [Indexed: 12/17/2022] Open
Abstract
During the development of mammalian neuromuscular junction (NMJ), the original supernumerary axon inputs are gradually eliminated, finally leaving each muscle fiber innervated by a single axon terminal. However, the molecular cues that mediate the elimination of redundant axon inputs remain unclear. Here we show that tumor necrosis factor-α (TNFα) expressed in postsynaptic muscle cells plays an important role in presynaptic axonal elimination at the NMJ. We found that intramuscular injection of TNFα into the levator auris longus (LAL) muscles caused disassociation of presynaptic nerve terminals from the postsynaptic acetylcholine receptor (AChR) clusters. By contrast, genetic ablation of TNFα globally or specifically in skeletal muscle cells, but not in motoneurons or Schwann cells, delayed the synaptic elimination. Moreover, ablation of TNFα in muscle cells attenuated the tendency of activity-dependent competition in a motoneuron-muscle coculture system. These results suggest a role of postsynaptic TNFα in the elimination of redundant synaptic inputs.
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Affiliation(s)
- Xiu-Qing Fu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210 China
| | - Jian Peng
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210 China
- State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, 200031 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Ai-Hua Wang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210 China
| | - Zhen-Ge Luo
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210 China
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13
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Molecular organization and function of vertebrate septate-like junctions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183211. [PMID: 32032590 DOI: 10.1016/j.bbamem.2020.183211] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 01/22/2020] [Accepted: 01/26/2020] [Indexed: 12/21/2022]
Abstract
Septate-like junctions display characteristic ladder-like ultrastructure reminiscent of the invertebrate epithelial septate junctions and are present at the paranodes of myelinated axons. The paranodal junctions where the myelin loops attach to the axon at the borders of the node of Ranvier provide both a paracellular barrier to ion diffusion and a lateral fence along the axonal membrane. The septate-like junctions constrain the proper distribution of nodal Na+ channels and juxtaparanodal K+ channels, which are required for the safe propagation of the nerve influx and rapid saltatory conduction. The paranodal cell adhesion molecules have been identified as target antigens in peripheral demyelinating autoimmune diseases and the pathogenic mechanisms described. This review aims at presenting the recent knowledge on the molecular and structural organization of septate-like junctions, their formation and stabilization during development, and how they are involved in demyelinating diseases.
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Hu B, Wang C, Chang Q, Yang W, Wu Z, Meng M, Qu F, Chen P, Zhang C, Zhang Y. NF155-overexpression promotes remyelination and functional restoration in a hypoxic-ischemic mixed neonatal rat forebrain cell culture system. Neurosci Lett 2020; 718:134743. [PMID: 31917235 DOI: 10.1016/j.neulet.2020.134743] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 12/31/2019] [Accepted: 01/03/2020] [Indexed: 01/24/2023]
Abstract
White matter injury caused by perinatal hypoxia-ischemia is characterized by myelination disorders; however, its pathophysiological mechanisms are not fully elucidated. The neurofascin 155 (NF155) protein, expressed in oligodendrocytes, is critical for myelination. Previous findings suggest that NF155 participates in the pathological mechanisms of developmental myelination disorders in hypoxic-ischemic cerebral white matter lesions, and it might regulate cytoskeletal changes. Therefore, we hypothesized that increased NF155 expression during the early stages of hypoxic oligodendrocyte injury helps normalize myelin sheath development and consequently improves neural function by repairing paranodal structures of myelin sheaths and regulating cytoskeletal changes. To test this hypothesis, we established a hypoxic-ischemic, mixed neonatal rat forebrain cell culture model. When NF155 expression was upregulated, synergistic effects occurred between this protein and the paranodal proteins CASPR and contactin. In addition, the expression of Rho GTPase family proteins that regulate key cytoskeletal pathways, myelin sheath structures, and functions were restored, and axonal structures acquired a clear and transparent appearance. These results suggest that NF155 may enable myelin sheath repair by repairing paranodal region structures and regulating oligodendrocyte cytoskeletal mechanisms. Overall, the present study provides new insights into the pathogenesis of hypoxic-ischemic cerebral white matter lesions.
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Affiliation(s)
- Bin Hu
- Department of Pediatrics, The Second Affiliated Hospital of the Army Medical University, Chongqing 400037, China
| | - Chengju Wang
- Department of Pediatrics, The Second Affiliated Hospital of the Army Medical University, Chongqing 400037, China
| | - Qin Chang
- Department of Pediatrics, The Second Affiliated Hospital of the Army Medical University, Chongqing 400037, China
| | - Wang Yang
- Department of Pediatrics, The Second Affiliated Hospital of the Army Medical University, Chongqing 400037, China
| | - Zhifeng Wu
- Department of Pediatrics, The Second Affiliated Hospital of the Army Medical University, Chongqing 400037, China
| | - Meng Meng
- Department of Pediatrics, The Second Affiliated Hospital of the Army Medical University, Chongqing 400037, China
| | - Fuxiang Qu
- Department of Pediatrics, The Second Affiliated Hospital of the Army Medical University, Chongqing 400037, China
| | - Penghui Chen
- Department of Neurobiology, School of Basic Medical Sciences, Army Medical University, Chongqing 400038, China
| | - Chunqing Zhang
- Department of Neurosurgery, The Second Affiliated Hospital of the Army Medical University, Chongqing 400037, China
| | - Yuping Zhang
- Department of Pediatrics, The Second Affiliated Hospital of the Army Medical University, Chongqing 400037, China.
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15
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Lee YI. Developmental neuromuscular synapse elimination: Activity-dependence and potential downstream effector mechanisms. Neurosci Lett 2019; 718:134724. [PMID: 31877335 DOI: 10.1016/j.neulet.2019.134724] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 12/18/2019] [Accepted: 12/23/2019] [Indexed: 12/12/2022]
Abstract
Synaptic connections initially formed during nervous system development undergo a significant transformation during nervous system maturation. Such maturation is essential for the proper architecture and function of the nervous system. Developmental synaptic transformation includes "synapse elimination," a process in which multiple immature presynaptic inputs converge at and compete for control of a common postsynaptic target. This developmental synaptic remodeling is best understood at mammalian neuromuscular junctions. It is well established that neuromuscular activity provides the impetus for the pruning of redundant motor axon inputs. Despite the dominant influence neuromuscular activity exerts on developmental synapse elimination, however, the downstream mechanisms of neuromuscular activity that affect synapse elimination remain poorly understood. Conversely, although several cellular and molecular effector mechanisms are known to impact synapse elimination, it is unclear whether they are modulated by neuromuscular activity. This review discusses how the motor neurons, synaptic glia and muscle fibers each contributes to the developmental phenomenon, and speculates how neuromuscular activity may modulate these contributions.
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Affiliation(s)
- Young Il Lee
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA.
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16
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Abstract
Maturation of neuronal circuits requires selective elimination of synaptic connections. Although neuron-intrinsic mechanisms are important in this process, it is increasingly recognized that glial cells also play a critical role. Without proper functioning of these cells, the number, morphology, and function of synaptic contacts are profoundly altered, resulting in abnormal connectivity and behavioral abnormalities. In addition to their role in synaptic refinement, glial cells have also been implicated in pathological synapse loss and dysfunction following injury or nervous system degeneration in adults. Although mechanisms regulating glia-mediated synaptic elimination are still being uncovered, it is clear this complex process involves many cues that promote and inhibit the removal of specific synaptic connections. Gaining a greater understanding of these signals and the contribution of different cell types will not only provide insight into this critical biological event but also be instrumental in advancing knowledge of brain development and neural disease.
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Affiliation(s)
- Daniel K. Wilton
- Department of Neurology and F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Lasse Dissing-Olesen
- Department of Neurology and F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Beth Stevens
- Department of Neurology and F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
- Stanley Center, Broad Institute, Cambridge, Massachusetts 02142, USA
- Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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17
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Lee YI. Differences in the constituent fiber types contribute to the intermuscular variation in the timing of the developmental synapse elimination. Sci Rep 2019; 9:8694. [PMID: 31213646 PMCID: PMC6582271 DOI: 10.1038/s41598-019-45090-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 05/28/2019] [Indexed: 11/09/2022] Open
Abstract
The emergence of a mature nervous system requires a significant refinement of the synaptic connections initially formed during development. Redundant synaptic connections are removed in a process known as synapse elimination. Synapse elimination has been extensively studied at the rodent neuromuscular junction (NMJ). Although several axons initially converge onto each postsynaptic muscle fiber, all redundant inputs are removed during early postnatal development until a single motor neuron innervates each NMJ. Neuronal activity as well as synaptic glia influence the course of synapse elimination. It is, however, unclear whether target muscle fibers are more than naïve substrates in this process. I examined the influence of target myofiber contractile properties on synapse elimination. The timing of redundant input removal in muscles examined correlates strongly with their proportion of slow myofibers: muscles with more slow fibers undergo elimination more slowly. Moreover, this intermuscular difference in the timing of synapse elimination appears to result from local differences in the rate of elimination on fast versus slow myofibers. These results, therefore, imply that differences in the constituent fiber types help account for the variation in the timing of the developmental synapse elimination between muscles and show that the muscle plays a role in the process.
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Affiliation(s)
- Young Il Lee
- Department of Biology, Texas A&M University, College Station, TX, 77843, Texas, USA.
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18
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Zhang SJ, Li XX, Yu Y, Chiu AP, Lo LH, To JC, Rowlands DK, Keng VW. Schwann cell-specific PTEN and EGFR dysfunctions affect neuromuscular junction development by impairing Agrin signaling and autophagy. Biochem Biophys Res Commun 2019; 515:50-56. [PMID: 31122699 DOI: 10.1016/j.bbrc.2019.05.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 05/02/2019] [Indexed: 10/26/2022]
Abstract
The neuromuscular junction (NMJ) is formed by motor nerve terminals, post-junctional muscle membranes, and terminal Schwann cells (SCs). The formation of NMJ requires complex and dynamic molecular interactions. Nerve- and muscle-derived molecules have been well characterized but the mechanistic involvement of SC in NMJ development remains poorly understood. SC-specific phosphatase and tensin homolog (Pten) inactivation and epidermal growth factor receptor (EGFR) overexpression (Dhh-Cre; Cnp-EGFR; Ptenflox/flox or DET) mice were used and NMJ malformation was observed in these mice. Acetylcholine receptors (AChRs) were distorted and varicose presynaptic nerve terminals appeared in the tibialis anterior (TA) muscle of DET mice. Agrin signaling related to NMJ development, was downregulated in TA muscle. Both RAS/MEK/ERK and PI3K/AKT/mTOR signaling pathways were activated in the sciatic nerves of DET mice. In addition, autophagy was downregulated in these sciatic nerves. Interestingly, the use of Torin 2, an mTOR inhibitor, rescued the phenotype. The downregulated-autophagy might account for Agrin signaling abnormity, which induced NMJ malformation. Taken together, our results indicate that SCs-specific Pten and EGFR cooperation are essential for NMJ development.
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Affiliation(s)
- Shi-Jie Zhang
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China; Department of Neurology, Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China; Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Xiao-Xiao Li
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Yuyu Yu
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Amy P Chiu
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Lilian H Lo
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Jeffrey C To
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Dewi K Rowlands
- Laboratory Animal Services Centre, The Chinese University of Hong Kong, Sha Tin, New Territories, Hong Kong SAR, China
| | - Vincent W Keng
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China.
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Kim MJ, Petratos S. Oligodendroglial Lineage Cells in Thyroid Hormone-Deprived Conditions. Stem Cells Int 2019; 2019:5496891. [PMID: 31182964 PMCID: PMC6515029 DOI: 10.1155/2019/5496891] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 03/20/2019] [Indexed: 01/06/2023] Open
Abstract
Oligodendrocytes are supporting glial cells that ensure the metabolism and homeostasis of neurons with specific synaptic axoglial interactions in the central nervous system. These require key myelinating glial trophic signals important for growth and metabolism. Thyroid hormone (TH) is one such trophic signal that regulates oligodendrocyte maturation, myelination, and oligodendroglial synaptic dynamics via either genomic or nongenomic pathways. The intracellular and extracellular transport of TH is facilitated by a specific transmembrane transporter known as the monocarboxylate transporter 8 (MCT8). Dysfunction of the MCT8 due to mutation, inhibition, or downregulation during brain development leads to inherited hypomyelination, which manifests as psychomotor retardation in the X-linked inherited Allan-Herndon-Dudley syndrome (AHDS). In particular, oligodendroglial-specific MCT8 deficiency may restrict the intracellular T3 availability, culminating in deficient metabolic communication between the oligodendrocytes and the neurons they ensheath, potentially promulgating neurodegenerative adult diseases such as multiple sclerosis (MS). Based on the therapeutic effects exhibited by TH in various preclinical studies, particularly related to its remyelinating potential, TH has now entered the initial stages of a clinical trial to test the therapeutic efficacy in relapsing-remitting MS patients (NCT02506751). However, TH analogs, such as DITPA or Triac, may well serve as future therapeutic options to rescue mature oligodendrocytes and/or promote oligodendrocyte precursor cell differentiation in an environment of MCT8 deficiency within the CNS. This review outlines the therapeutic strategies to overcome the differentiation blockade of oligodendrocyte precursors and maintain mature axoglial interactions in TH-deprived conditions.
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Affiliation(s)
- Min Joung Kim
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, Victoria 3004, Australia
| | - Steven Petratos
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, Victoria 3004, Australia
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20
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Smigiel R, Sherman DL, Rydzanicz M, Walczak A, Mikolajkow D, Krolak-Olejnik B, Kosińska J, Gasperowicz P, Biernacka A, Stawinski P, Marciniak M, Andrzejewski W, Boczar M, Krajewski P, Sasiadek MM, Brophy PJ, Ploski R. Homozygous mutation in the Neurofascin gene affecting the glial isoform of Neurofascin causes severe neurodevelopment disorder with hypotonia, amimia and areflexia. Hum Mol Genet 2018; 27:3669-3674. [PMID: 30124836 PMCID: PMC6196652 DOI: 10.1093/hmg/ddy277] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 07/20/2018] [Accepted: 07/20/2018] [Indexed: 11/27/2022] Open
Abstract
The Neurofascins (NFASCs) are a family of proteins encoded by alternative transcripts of NFASC that cooperate in the assembly of the node of Ranvier in myelinated nerves. Differential expression of NFASC in neurons and glia presents a remarkable example of cell-type specific expression of protein isoforms with a common overall function. In mice there are three NFASC isoforms: Nfasc186 and Nfasc140, located in the axonal membrane at the node of Ranvier, and Nfasc155, a glial component of the paranodal axoglial junction. Nfasc186 and Nfasc155 are the major isoforms at mature nodes and paranodes, respectively. Conditional deletion of the glial isoform Nfasc155 in mice causes severe motor coordination defects and death at 16-17 days after birth. We describe a proband with severe congenital hypotonia, contractures of fingers and toes, and no reaction to touch or pain. Whole exome sequencing revealed a homozygous NFASC variant chr1:204953187-C>T (rs755160624). The variant creates a premature stop codon in 3 out of four NFASC human transcripts and is predicted to specifically eliminate Nfasc155 leaving neuronal Neurofascin intact. The selective absence of Nfasc155 and disruption of the paranodal junction was confirmed by an immunofluorescent study of skin biopsies from the patient versus control. We propose that the disease in our proband is the first reported example of genetic deficiency of glial Neurofascin isoforms in humans and that the severity of the condition reflects the importance of the Nfasc155 in forming paranodal axoglial junctions and in determining the structure and function of the node of Ranvier.
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Affiliation(s)
- Robert Smigiel
- Department of Pediatrics and Rare Disorders, Wroclaw Medical University, Wroclaw 51-618, Poland
| | - Diane L Sherman
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Małgorzata Rydzanicz
- Department of Medical Genetics, Medical University of Warsaw, Warsaw 02-106, Poland
| | - Anna Walczak
- Department of Medical Genetics, Medical University of Warsaw, Warsaw 02-106, Poland
| | - Dorota Mikolajkow
- Department of Neonatology, Wroclaw Medical University, Wroclaw 55-556, Poland
| | | | - Joanna Kosińska
- Department of Medical Genetics, Medical University of Warsaw, Warsaw 02-106, Poland
| | - Piotr Gasperowicz
- Department of Medical Genetics, Medical University of Warsaw, Warsaw 02-106, Poland
| | - Anna Biernacka
- Department of Medical Genetics, Medical University of Warsaw, Warsaw 02-106, Poland
| | - Piotr Stawinski
- Department of Medical Genetics, Medical University of Warsaw, Warsaw 02-106, Poland
| | - Malgorzata Marciniak
- Department of Neonatology, Provincial Specialist Hospital, Wroclaw 51-124, Poland
| | | | - Maria Boczar
- Clinics of Surgery of Children and Adolescents, Institute of Mother and Child, Warsaw 01-211, Poland
| | - Paweł Krajewski
- Department of Forensic Medicine, Medical University of Warsaw, Warsaw 02-007, Poland
| | - Maria M Sasiadek
- Department of Genetics, Wroclaw Medical University, Wroclaw 50-367, Poland
| | - Peter J Brophy
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Rafal Ploski
- Department of Medical Genetics, Medical University of Warsaw, Warsaw 02-106, Poland
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21
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Mansilla A, Jordán-Álvarez S, Santana E, Jarabo P, Casas-Tintó S, Ferrús A. Molecular mechanisms that change synapse number. J Neurogenet 2018; 32:155-170. [DOI: 10.1080/01677063.2018.1506781] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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22
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Lanuza MA, Tomàs J, Garcia N, Cilleros-Mañé V, Just-Borràs L, Tomàs M. Axonal competition and synapse elimination during neuromuscular junction development. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2018.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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23
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Affiliation(s)
- Lei Li
- Department of Neuroscience, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Wen-Cheng Xiong
- Department of Neuroscience, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
- Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio 44106, USA
| | - Lin Mei
- Department of Neuroscience, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
- Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio 44106, USA
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24
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Schwann Cells in Neuromuscular Junction Formation and Maintenance. J Neurosci 2017; 36:9770-81. [PMID: 27656017 DOI: 10.1523/jneurosci.0174-16.2016] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 07/14/2016] [Indexed: 01/18/2023] Open
Abstract
UNLABELLED The neuromuscular junction (NMJ) is a tripartite synapse that is formed by motor nerve terminals, postjunctional muscle membranes, and terminal Schwann cells (TSCs) that cover the nerve-muscle contact. NMJ formation requires intimate communications among the three different components. Unlike nerve-muscle interaction, which has been well characterized, less is known about the role of SCs in NMJ formation and maintenance. We show that SCs in mice lead nerve terminals to prepatterned AChRs. Ablating SCs at E8.5 (i.e., prior nerve arrival at the clusters) had little effect on aneural AChR clusters at E13.5, suggesting that SCs may not be necessary for aneural clusters. SC ablation at E12.5, a time when phrenic nerves approach muscle fibers, resulted in smaller and fewer nerve-induced AChR clusters; however, SC ablation at E15.5 reduced AChR cluster size but had no effect on cluster density, suggesting that SCs are involved in AChR cluster maturation. Miniature endplate potential amplitude, but not frequency, was reduced when SCs were ablated at E15.5, suggesting that postsynaptic alterations may occur ahead of presynaptic deficits. Finally, ablation of SCs at P30, after NMJ maturation, led to NMJ fragmentation and neuromuscular transmission deficits. Miniature endplate potential amplitude was reduced 3 d after SC ablation, but both amplitude and frequency were reduced 6 d after. Together, these results indicate that SCs are not only required for NMJ formation, but also necessary for its maintenance; and postsynaptic function and structure appeared to be more sensitive to SC ablation. SIGNIFICANCE STATEMENT Neuromuscular junctions (NMJs) are critical for survival and daily functioning. Defects in NMJ formation during development or maintenance in adulthood result in debilitating neuromuscular disorders. The role of Schwann cells (SCs) in NMJ formation and maintenance was not well understood. We genetically ablated SCs during development and after NMJ formation to investigate the consequences of the ablation. This study reveals a critical role of SCs in NMJ formation as well as maintenance.
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25
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Park SY, Jang SY, Shin YK, Jung DK, Yoon BA, Kim JK, Jo YR, Lee HJ, Park HT. The Scaffolding Protein, Grb2-associated Binder-1, in Skeletal Muscles and Terminal Schwann Cells Regulates Postnatal Neuromuscular Synapse Maturation. Exp Neurobiol 2017; 26:141-150. [PMID: 28680299 PMCID: PMC5491582 DOI: 10.5607/en.2017.26.3.141] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 06/08/2017] [Accepted: 06/08/2017] [Indexed: 01/10/2023] Open
Abstract
The vertebrate neuromuscular junction (NMJ) is considered as a "tripartite synapse" consisting of a motor axon terminal, a muscle endplate, and terminal Schwann cells that envelope the motor axon terminal. The neuregulin 1 (NRG1)-ErbB2 signaling pathway plays an important role in the development of the NMJ. We previously showed that Grb2-associated binder 1 (Gab1), a scaffolding mediator of receptor tyrosine kinase signaling, is required for NRG1-induced peripheral nerve myelination. Here, we determined the role of Gab1 in the development of the NMJ using muscle-specific conditional Gab1 knockout mice. The mutant mice showed delayed postnatal maturation of the NMJ. Furthermore, the selective loss of the gab1 gene in terminal Schwann cells produced delayed synaptic elimination with abnormal morphology of the motor endplate, suggesting that Gab1 in both muscles and terminal Schwann cells is required for proper NMJ development. Gab1 in terminal Schwann cells appeared to regulate the number and process elongation of terminal Schwann cells during synaptic elimination. However, Gab2 knockout mice did not show any defects in the development of the NMJ. Considering the role of Gab1 in postnatal peripheral nerve myelination, our findings suggest that Gab1 is a pleiotropic and important component of NRG1 signals during postnatal development of the peripheral neuromuscular system.
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Affiliation(s)
- So Young Park
- Department of Physiology, College of Medicine, Dong-A University, Busan 49201, Korea
| | - So Young Jang
- Department of Physiology, College of Medicine, Dong-A University, Busan 49201, Korea
| | - Yoon Kyoung Shin
- Department of Physiology, College of Medicine, Dong-A University, Busan 49201, Korea
| | - Dong Keun Jung
- Department of Physiology, College of Medicine, Dong-A University, Busan 49201, Korea
| | - Byeol A Yoon
- Department of Peripheral Neuropath Research Center (PNRC), College of Medicine, Dong-A University, Busan 49201, Korea
| | - Jong Kook Kim
- Department of Peripheral Neuropath Research Center (PNRC), College of Medicine, Dong-A University, Busan 49201, Korea
| | - Young Rae Jo
- Department of Physiology, College of Medicine, Dong-A University, Busan 49201, Korea
| | - Hye Jeong Lee
- Department of Pharmacology, College of Medicine, Dong-A University, Busan 49201, Korea
| | - Hwan Tae Park
- Department of Physiology, College of Medicine, Dong-A University, Busan 49201, Korea
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26
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Saifetiarova J, Liu X, Taylor AM, Li J, Bhat MA. Axonal domain disorganization in Caspr1 and Caspr2 mutant myelinated axons affects neuromuscular junction integrity, leading to muscle atrophy. J Neurosci Res 2017; 95:1373-1390. [PMID: 28370195 DOI: 10.1002/jnr.24052] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 02/14/2017] [Accepted: 02/24/2017] [Indexed: 12/19/2022]
Abstract
Bidirectional interactions between neurons and myelinating glial cells result in formation of axonal domains along myelinated fibers. Loss of axonal domains leads to detrimental consequences on nerve structure and function, resulting in reduced conductive properties and the diminished ability to reliably transmit signals to the targets they innervate. Thus, impairment of peripheral myelinated axons that project to the surface of muscle fibers and form neuromuscular junction (NMJ) synapses leads to muscle dysfunction. The goal of our studies was to determine how altered electrophysiological properties due to axonal domain disorganization lead to muscle pathology, which is relevant to a variety of peripheral neuropathies, demyelinating diseases, and neurodegenerative disorders. Using conventional Contactin-Associated Protein 1 (Caspr1) and Caspr2 single or double mutants with disrupted paranodal, juxtaparanodal, or both regions, respectively, in peripheral myelinated axons, we correlated defects in NMJ integrity and muscle pathology. Our data show that loss of axonal domains in Caspr1 and Caspr2 single and double mutants primarily alters distal myelinated fibers together with presynaptic terminals, eventually leading to NMJ denervation and reduction in postsynaptic endplate areas. Moreover, reduction in conductive properties of peripheral myelinated fibers together with NMJ disintegration leads to muscle atrophy in Caspr1 mutants or muscle fiber degeneration accompanied by mitochondrial dysfunction in Caspr1/Caspr2 double mutants. Together, our data indicate that proper organization of axonal domains in myelinated fibers is critical for optimal propagation of electrical signals, NMJ integrity, and muscle health, and provide insights into a wide range of pathologies that result in reduced nerve conduction leading to muscle atrophy. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Julia Saifetiarova
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas
| | - Xi Liu
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas.,Xiangya School of Medicine, Central South University, Changsha, China
| | - Anna M Taylor
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas
| | - Jie Li
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas
| | - Manzoor A Bhat
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas
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27
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Lakhani S, Doan R, Almureikhi M, Partlow JN, Al Saffar M, Elsaid MF, Alaaraj N, James Barkovich A, Walsh CA, Ben-Omran T. Identification of a novel CNTNAP1 mutation causing arthrogryposis multiplex congenita with cerebral and cerebellar atrophy. Eur J Med Genet 2017; 60:245-249. [PMID: 28254648 DOI: 10.1016/j.ejmg.2017.02.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 02/01/2017] [Accepted: 02/26/2017] [Indexed: 01/18/2023]
Abstract
Arthrogryposis multiplex congenital, the occurrence of multiple joint contractures at birth, can in some cases be accompanied by insufficient myelination of peripheral nerves, muscular hypotonia, reduced tendon reflexes, and respiratory insufficiency. Recently mutations in the CASPR/CNTN1 complex have been associated with similar severe phenotypes and CNTNAP1 gene mutations, causing loss of the CASPR protein, were shown to cause severe, prenatal onset arthrogryposis multiplex congenita in four unrelated families. Here we report a consanguineous Arab family from Qatar with three children having an early lethal form of arthrogryposis multiplex congenita and a novel frameshift mutation in CNTNAP1. We further expand the existing CNTNAP1-associated phenotype to include profound cerebral and cerebellar atrophy.
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Affiliation(s)
- Shenela Lakhani
- Section of Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Qatar
| | - Ryan Doan
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Mariam Almureikhi
- Section of Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Qatar
| | - Jennifer N Partlow
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA, 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA, 02115, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Muna Al Saffar
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA, 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA, 02115, USA; Department of Pediatrics, Faculty of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Mahmoud F Elsaid
- Section of Neurology, Department of Pediatrics, Hamad Medical Corporation, Qatar
| | - Nada Alaaraj
- Section of Children Development and Rehabilitation, Department of Pediatrics, Hamad Medical Corporation, Qatar
| | - A James Barkovich
- Pediatric Neuroradiology, Department of Neuroradiology, University of California, San Francisco, San Francisco, CA, 94143, USA
| | - Christopher A Walsh
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Boston, MA, 02115, USA; Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA, 02115, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, 02115, USA; Harvard Medical School, Boston, MA, 02115, USA
| | - Tawfeg Ben-Omran
- Section of Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Qatar.
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28
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Rodríguez-Molina JF, Lopez-Anido C, Ma KH, Zhang C, Olson T, Muth KN, Weider M, Svaren J. Dual specificity phosphatase 15 regulates Erk activation in Schwann cells. J Neurochem 2017; 140:368-382. [PMID: 27891578 PMCID: PMC5250571 DOI: 10.1111/jnc.13911] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/15/2016] [Accepted: 11/21/2016] [Indexed: 12/20/2022]
Abstract
Schwann cells and oligodendrocytes are the myelinating cells of the peripheral and central nervous system, respectively. Despite having different myelin components and different transcription factors driving their terminal differentiation there are shared molecular mechanisms between the two. Sox10 is one common transcription factor required for several steps in development of myelinating glia. However, other factors are divergent as Schwann cells need the transcription factor early growth response 2/Krox20 and oligodendrocytes require Myrf. Likewise, some signaling pathways, like the Erk1/2 kinases, are necessary in both cell types for proper myelination. Nonetheless, the molecular mechanisms that control this shared signaling pathway in myelinating cells remain only partially characterized. The hypothesis of this study is that signaling pathways that are similarly regulated in both Schwann cells and oligodendrocytes play central roles in coordinating the differentiation of myelinating glia. To address this hypothesis, we have used genome-wide binding data to identify a relatively small set of genes that are similarly regulated by Sox10 in myelinating glia. We chose one such gene encoding Dual specificity phosphatase 15 (Dusp15) for further analysis in Schwann cell signaling. RNA interference and gene deletion by genome editing in cultured RT4 and primary Schwann cells showed Dusp15 is necessary for full activation of Erk1/2 phosphorylation. In addition, we show that Dusp15 represses expression of several myelin genes, including myelin basic protein. The data shown here support a mechanism by which early growth response 2 activates myelin genes, but also induces a negative feedback loop through Dusp15 to limit over-expression of myelin genes.
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Affiliation(s)
- José F. Rodríguez-Molina
- Cellular and Molecular Pathology Graduate Program, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Camila Lopez-Anido
- Comparative Biomedical Sciences Graduate Program, University of Wisconsin-Madison, Madison, WI 53705, USA
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Ki H. Ma
- Cellular and Molecular Pathology Graduate Program, University of Wisconsin-Madison, Madison, WI 53705, USA
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Chongyu Zhang
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Tyler Olson
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Katharina N. Muth
- Institut für Biochemie, Emil-Fischer-Zentrum, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Matthias Weider
- Institut für Biochemie, Emil-Fischer-Zentrum, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - John Svaren
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53705, USA
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29
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Terni B, López-Murcia FJ, Llobet A. Role of neuron-glia interactions in developmental synapse elimination. Brain Res Bull 2016; 129:74-81. [PMID: 27601093 DOI: 10.1016/j.brainresbull.2016.08.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 08/19/2016] [Accepted: 08/31/2016] [Indexed: 11/16/2022]
Abstract
During the embryonic development of the nervous system there is a massive formation of synapses. However, the exuberant connectivity present after birth must be pruned during postnatal growth to optimize the function of neuronal circuits. Whilst glial cells play a fundamental role in the formation of early synaptic contacts, their contribution to developmental modifications of established synapses is not well understood. The present review aims to highlight the various roles of glia in the developmental refinement of embryonic synaptic connectivity. We summarize recent evidences linking secretory abilities of glial cells to the disassembly of synaptic contacts that are complementary of a well-established phagocytic role. Considering a theoretical framework, it is discussed how release of glial molecules could be relevant to the developmental refinement of synaptic connectivity. Finally, we propose a three-stage model of synapse elimination in which neurons and glia are functionally associated to timely eliminate synapses.
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Affiliation(s)
- Beatrice Terni
- Laboratory of Neurobiology, Department of Pathology and Experimental Therapeutics, Institute of Neurosciences, University of Barcelona and Bellvitge Biomedical Research Institute (IDIBELL), 08907 L'Hospitalet de Llobregat, Barcelona, Spain
| | - Francisco José López-Murcia
- Laboratory of Neurobiology, Department of Pathology and Experimental Therapeutics, Institute of Neurosciences, University of Barcelona and Bellvitge Biomedical Research Institute (IDIBELL), 08907 L'Hospitalet de Llobregat, Barcelona, Spain
| | - Artur Llobet
- Laboratory of Neurobiology, Department of Pathology and Experimental Therapeutics, Institute of Neurosciences, University of Barcelona and Bellvitge Biomedical Research Institute (IDIBELL), 08907 L'Hospitalet de Llobregat, Barcelona, Spain.
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30
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Palavicini JP, Wang C, Chen L, Ahmar S, Higuera JD, Dupree JL, Han X. Novel molecular insights into the critical role of sulfatide in myelin maintenance/function. J Neurochem 2016; 139:40-54. [PMID: 27417284 DOI: 10.1111/jnc.13738] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 06/17/2016] [Accepted: 06/22/2016] [Indexed: 01/19/2023]
Abstract
Cerebroside sulfotransferase (CST) catalyzes the production of sulfatide, a major class of myelin-specific lipids. CST knockout (CST(-/-) ) mice in which sulfatide is completely depleted are born healthy, but display myelin abnormalities and progressive tremors starting at 4-6 weeks of age. Although these phenotypes suggest that sulfatide plays a critical role in myelin maintenance/function, the underlying mechanisms remain largely unknown. We analyzed the major CNS myelin proteins and the major lipids enriched in the myelin in a spatiotemporal manner. We found a one-third reduction of the major compact myelin proteins (myelin basic protein, myelin basic protein, and proteolipid protein, PLP) and an equivalent post-developmental loss of myelin lipids, providing the molecular basis behind the thinner myelin sheaths. Our lipidomics data demonstrated that the observed global reduction of myelin lipid content was not because of an increase of lipid degradation but rather to the reduction of their synthesis by oligodendrocytes. We also showed that sulfatide depletion leads to region-specific effects on non-compact myelin, dramatically affecting the paranode (neurofascin 155) and the major inner tongue myelin protein (myelin-associated glycoprotein). Moreover, we demonstrated that sulfatide promotes the interaction between adjacent PLP extracellular domains, evidenced by a progressive decline of high molecular weight PLP complexes in CST(-/-) mice, providing an explanation at a molecular level regarding the uncompacted myelin sheaths. Finally, we proposed that the dramatic losses of neurofascin 155 and PLP interactions are responsible for the progressive tremors and eventual ataxia. In summary, we unraveled novel molecular insights into the critical role of sulfatide in myelin maintenance/function. Cerebroside sulfotransferase (CST) catalyzes the production of sulfatide, a major class of myelin-specific lipids. CST knockout (CST(-/-) ) mice in which sulfatide is completely depleted are born healthy, but display myelin abnormalities We show in our study that sulfatide depletion leads to losses of myelin proteins and lipids, and impairment of myelin functions, unraveling novel molecular insights into the critical role of sulfatide in myelin maintenance/function.
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Affiliation(s)
- Juan Pablo Palavicini
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Chunyan Wang
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Linyuan Chen
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Sareen Ahmar
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Juan Diego Higuera
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Jeffrey L Dupree
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia, USA.,Research Division, McGuire Veterans Affairs Medical Center, Richmond, Virginia, USA
| | - Xianlin Han
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA.
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31
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Tetruashvily MM, McDonald MA, Boulanger LM, Boulanger LM. MHCI promotes developmental synapse elimination and aging-related synapse loss at the vertebrate neuromuscular junction. Brain Behav Immun 2016; 56:197-208. [PMID: 26802986 PMCID: PMC5813483 DOI: 10.1016/j.bbi.2016.01.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 01/12/2016] [Accepted: 01/12/2016] [Indexed: 12/23/2022] Open
Abstract
Synapse elimination at the developing neuromuscular junction (NMJ) sculpts motor circuits, and synapse loss at the aging NMJ drives motor impairments that are a major cause of loss of independence in the elderly. Here we provide evidence that at the NMJ, both developmental synapse elimination and aging-related synapse loss are promoted by specific immune proteins, members of the major histocompatibility complex class I (MHCI). MHCI is expressed at the developing NMJ, and three different methods of reducing MHCI function all disrupt synapse elimination during the second postnatal week, leaving some muscle fibers multiply-innervated, despite otherwise outwardly normal synapse formation and maturation. Conversely, overexpressing MHCI modestly accelerates developmental synapse elimination. MHCI levels at the NMJ rise with aging, and reducing MHCI levels ameliorates muscle denervation in aged mice. These findings identify an unexpected role for MHCI in the elimination of neuromuscular synapses during development, and indicate that reducing MHCI levels can preserve youthful innervation of aging muscle.
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Affiliation(s)
- Mazell M. Tetruashvily
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544,Rutgers Robert Wood Johnson Medical School, Piscataway, NJ 08854
| | - Marin A. McDonald
- Department of Neurosciences, University of California, San Diego 92093,Medical Scientist Training Program, University of California, San Diego 92093
| | - Lisa M. Boulanger
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544,Department of Neurosciences, University of California, San Diego 92093,Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544,Correspondence to:
| | - Lisa M Boulanger
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, United States; Department of Neurosciences, University of California, San Diego 92093, United States; Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, United States.
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32
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Hunter G, Powis RA, Jones RA, Groen EJN, Shorrock HK, Lane FM, Zheng Y, Sherman DL, Brophy PJ, Gillingwater TH. Restoration of SMN in Schwann cells reverses myelination defects and improves neuromuscular function in spinal muscular atrophy. Hum Mol Genet 2016; 25:2853-2861. [PMID: 27170316 PMCID: PMC5181642 DOI: 10.1093/hmg/ddw141] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 04/27/2016] [Accepted: 04/29/2016] [Indexed: 12/19/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a neuromuscular disease caused by low levels of SMN protein, primarily affecting lower motor neurons. Recent evidence from SMA and related conditions suggests that glial cells can influence disease severity. Here, we investigated the role of glial cells in the peripheral nervous system by creating SMA mice selectively overexpressing SMN in myelinating Schwann cells (Smn−/−;SMN2tg/0;SMN1SC). Restoration of SMN protein levels restricted solely to Schwann cells reversed myelination defects, significantly improved neuromuscular function and ameliorated neuromuscular junction pathology in SMA mice. However, restoration of SMN in Schwann cells had no impact on motor neuron soma loss from the spinal cord or ongoing systemic and peripheral pathology. This study provides evidence for a defined, intrinsic contribution of glial cells to SMA disease pathogenesis and suggests that therapies designed to include Schwann cells in their target tissues are likely to be required in order to rescue myelination defects and associated disease symptoms.
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Affiliation(s)
- Gillian Hunter
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK,
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK and
| | - Rachael A Powis
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK,
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK and
| | - Ross A Jones
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK,
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK and
| | - Ewout J N Groen
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK,
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK and
| | - Hannah K Shorrock
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK,
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK and
| | - Fiona M Lane
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK,
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK and
| | - Yinan Zheng
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK,
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK and
| | - Diane L Sherman
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - Peter J Brophy
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - Thomas H Gillingwater
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK,
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK and
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33
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Cherra SJ, Jin Y. A Two-Immunoglobulin-Domain Transmembrane Protein Mediates an Epidermal-Neuronal Interaction to Maintain Synapse Density. Neuron 2016; 89:325-36. [PMID: 26777275 PMCID: PMC4871750 DOI: 10.1016/j.neuron.2015.12.024] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 08/17/2015] [Accepted: 12/08/2015] [Indexed: 02/06/2023]
Abstract
Synaptic maintenance is essential for neural circuit function. In the C. elegans locomotor circuit, motor neurons are in direct contact with the epidermis. Here, we reveal a novel epidermal-neuronal interaction mediated by a two-immunoglobulin domain transmembrane protein, ZIG-10, that is necessary for maintaining cholinergic synapse density. ZIG-10 is localized at the cell surface of epidermis and cholinergic motor neurons, with high levels at areas adjacent to synapses. Loss of zig-10 increases the number of cholinergic excitatory synapses and exacerbates convulsion behavior in a seizure model. Mis-expression of zig-10 in GABAergic inhibitory neurons reduces GABAergic synapse number, dependent on the presence of ZIG-10 in the epidermis. Furthermore, ZIG-10 interacts with the tyrosine kinase SRC-2 to regulate the phagocytic activity of the epidermis to restrict cholinergic synapse number. Our studies demonstrate the highly specific roles of non-neuronal cells in modulating neural circuit function, through neuron-type-specific maintenance of synapse density.
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Affiliation(s)
- Salvatore J. Cherra
- Division of Biological Sciences, Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yishi Jin
- Division of Biological Sciences, Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
- Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA
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34
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Amorim IS, Mitchell NL, Palmer DN, Sawiak SJ, Mason R, Wishart TM, Gillingwater TH. Molecular neuropathology of the synapse in sheep with CLN5 Batten disease. Brain Behav 2015; 5:e00401. [PMID: 26664787 PMCID: PMC4667763 DOI: 10.1002/brb3.401] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 08/25/2015] [Accepted: 09/02/2015] [Indexed: 12/26/2022] Open
Abstract
AIMS Synapses represent a major pathological target across a broad range of neurodegenerative conditions. Recent studies addressing molecular mechanisms regulating synaptic vulnerability and degeneration have relied heavily on invertebrate and mouse models. Whether similar molecular neuropathological changes underpin synaptic breakdown in large animal models and in human patients with neurodegenerative disease remains unclear. We therefore investigated whether molecular regulators of synaptic pathophysiology, previously identified in Drosophila and mouse models, are similarly present and modified in the brain of sheep with CLN5 Batten disease. METHODS Gross neuropathological analysis of CLN5 Batten disease sheep and controls was used alongside postmortem MRI imaging to identify affected brain regions. Synaptosome preparations were then generated and quantitative fluorescent Western blotting used to determine and compare levels of synaptic proteins. RESULTS The cortex was particularly affected by regional neurodegeneration and synaptic loss in CLN5 sheep, whilst the cerebellum was relatively spared. Quantitative assessment of the protein content of synaptosome preparations revealed significant changes in levels of seven out of eight synaptic neurodegeneration proteins investigated in the motor cortex, but not cerebellum, of CLN5 sheep (α-synuclein, CSP-α, neurofascin, ROCK2, calretinin, SIRT2, and UBR4). CONCLUSIONS Synaptic pathology is a robust correlate of region-specific neurodegeneration in the brain of CLN5 sheep, driven by molecular pathways similar to those reported in Drosophila and rodent models. Thus, large animal models, such as sheep, represent ideal translational systems to develop and test therapeutics aimed at delaying or halting synaptic pathology for a range of human neurodegenerative conditions.
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Affiliation(s)
- Inês S Amorim
- Centre for Integrative Physiology University of Edinburgh Hugh Robson Building Edinburgh UK ; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh Hugh Robson Building Edinburgh UK
| | - Nadia L Mitchell
- Department of Molecular Biosciences Faculty of Agricultural and Life Sciences and Batten Animal Research Network Lincoln University Christchurch New Zealand
| | - David N Palmer
- Department of Molecular Biosciences Faculty of Agricultural and Life Sciences and Batten Animal Research Network Lincoln University Christchurch New Zealand
| | - Stephen J Sawiak
- Department of Physiology, Development and Neuroscience University of Cambridge Downing Street Cambridge UK ; Wolfson Brain Imaging Centre University of Cambridge Box 65 Addenbrooke's Hospital Hills Road Cambridge UK
| | - Roger Mason
- Department of Physiology, Development and Neuroscience University of Cambridge Downing Street Cambridge UK
| | - Thomas M Wishart
- Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh Hugh Robson Building Edinburgh UK ; Division of Neurobiology The Roslin Institute and Royal (Dick) School of Veterinary Studies University of Edinburgh Edinburgh UK
| | - Thomas H Gillingwater
- Centre for Integrative Physiology University of Edinburgh Hugh Robson Building Edinburgh UK ; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh Hugh Robson Building Edinburgh UK
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35
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Henstridge CM, Jackson RJ, Kim JM, Herrmann AG, Wright AK, Harris SE, Bastin ME, Starr JM, Wardlaw J, Gillingwater TH, Smith C, McKenzie CA, Cox SR, Deary IJ, Spires-Jones TL. Post-mortem brain analyses of the Lothian Birth Cohort 1936: extending lifetime cognitive and brain phenotyping to the level of the synapse. Acta Neuropathol Commun 2015; 3:53. [PMID: 26335101 PMCID: PMC4559320 DOI: 10.1186/s40478-015-0232-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 08/19/2015] [Indexed: 12/14/2022] Open
Abstract
INTRODUCTION Non-pathological, age-related cognitive decline varies markedly between individuals andplaces significant financial and emotional strain on people, their families and society as a whole.Understanding the differential age-related decline in brain function is critical not only for the development oftherapeutics to prolong cognitive health into old age, but also to gain insight into pathological ageing suchas Alzheimer's disease. The Lothian Birth Cohort of 1936 (LBC1936) comprises a rare group of people forwhom there are childhood cognitive test scores and longitudinal cognitive data during older age, detailedstructural brain MRI, genome-wide genotyping, and a multitude of other biological, psycho-social, andepidemiological data. Synaptic integrity is a strong indicator of cognitive health in the human brain;however, until recently, it was prohibitively difficult to perform detailed analyses of synaptic and axonalstructure in human tissue sections. We have adapted a novel method of tissue preparation at autopsy toallow the study of human synapses from the LBC1936 cohort in unprecedented morphological andmolecular detail, using the high-resolution imaging techniques of array tomography and electronmicroscopy. This allows us to analyze the brain at sub-micron resolution to assess density, proteincomposition and health of synapses. Here we present data from the first donated LBC1936 brain andcompare our findings to Alzheimer's diseased tissue to highlight the differences between healthy andpathological brain ageing. RESULTS Our data indicates that compared to an Alzheimer's disease patient, the cognitively normalLBC1936 participant had a remarkable degree of preservation of synaptic structures. However,morphological and molecular markers of degeneration in areas of the brain associated with cognition(prefrontal cortex, anterior cingulate cortex, and superior temporal gyrus) were observed. CONCLUSIONS Our novel post-mortem protocol facilitates high-resolution neuropathological analysis of the well-characterized LBC1936 cohort, extending phenotyping beyond cognition and in vivo imaging to nowinclude neuropathological changes, at the level of single synapses. This approach offers an unprecedentedopportunity to study synaptic and axonal integrity during ageing and how it contributes to differences in agerelatedcognitive change.
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Affiliation(s)
- Christopher M Henstridge
- Centre for Cognitive and Neural Systems, University of Edinburgh, 1 George Square, Edinburgh, EH8 9JZ, UK
| | - Rosemary J Jackson
- Centre for Cognitive and Neural Systems, University of Edinburgh, 1 George Square, Edinburgh, EH8 9JZ, UK
| | - JeeSoo M Kim
- Centre for Cognitive and Neural Systems, University of Edinburgh, 1 George Square, Edinburgh, EH8 9JZ, UK
| | - Abigail G Herrmann
- Centre for Cognitive and Neural Systems, University of Edinburgh, 1 George Square, Edinburgh, EH8 9JZ, UK
| | - Ann K Wright
- Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
| | - Sarah E Harris
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, UK
- Medical Genetics Section, University of Edinburgh Centre for Genomic and Experimental Medicine and MRC Institute of Genetics and Molecular Medicine, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Mark E Bastin
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, UK
- Centre for Clinical Brain Sciences, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK
| | - John M Starr
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, UK
- Geriatric Medicine Unit, University of Edinburgh, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Joanna Wardlaw
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, UK
- Centre for Clinical Brain Sciences, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK
| | - Thomas H Gillingwater
- Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
| | - Colin Smith
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, UK
- Centre for Clinical Brain Sciences, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK
| | - Chris-Anne McKenzie
- Centre for Clinical Brain Sciences, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK
| | - Simon R Cox
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, UK
- Department of Psychology, CCACE, University of Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, UK
| | - Ian J Deary
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, UK.
- Department of Psychology, CCACE, University of Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, UK.
| | - Tara L Spires-Jones
- Centre for Cognitive and Neural Systems, University of Edinburgh, 1 George Square, Edinburgh, EH8 9JZ, UK.
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK.
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