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Lisak RP, Nedelkoska L, Benjamins JA. Effects of dextromethorphan on glial cell function: Proliferation, maturation, and protection from cytotoxic molecules. Glia 2014; 62:751-62. [DOI: 10.1002/glia.22639] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 01/20/2014] [Accepted: 01/22/2014] [Indexed: 12/11/2022]
Affiliation(s)
- Robert P. Lisak
- Department of Neurology; Wayne State University School of Medicine; Detroit Missouri
- Department of Immunology/Microbiology; Wayne State University School of Medicine; Detroit Missouri
| | - Liljana Nedelkoska
- Department of Neurology; Wayne State University School of Medicine; Detroit Missouri
| | - Joyce A. Benjamins
- Department of Neurology; Wayne State University School of Medicine; Detroit Missouri
- Department of Immunology/Microbiology; Wayne State University School of Medicine; Detroit Missouri
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52
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Lundgaard I, Luzhynskaya A, Stockley JH, Wang Z, Evans KA, Swire M, Volbracht K, Gautier HOB, Franklin RJM, ffrench-Constant C, Attwell D, Káradóttir RT. Neuregulin and BDNF induce a switch to NMDA receptor-dependent myelination by oligodendrocytes. PLoS Biol 2013; 11:e1001743. [PMID: 24391468 PMCID: PMC3876980 DOI: 10.1371/journal.pbio.1001743] [Citation(s) in RCA: 239] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 11/13/2013] [Indexed: 11/20/2022] Open
Abstract
Neuregulin switches oligodendrocytes between two modes of myelination: from a neuronal activity–independent mode to a myelin-increasing, neuronal activity–dependent, mechanism that involves glutamate release and NMDA receptor activation. Myelination is essential for rapid impulse conduction in the CNS, but what determines whether an individual axon becomes myelinated remains unknown. Here we show, using a myelinating coculture system, that there are two distinct modes of myelination, one that is independent of neuronal activity and glutamate release and another that depends on neuronal action potentials releasing glutamate to activate NMDA receptors on oligodendrocyte lineage cells. Neuregulin switches oligodendrocytes from the activity-independent to the activity-dependent mode of myelination by increasing NMDA receptor currents in oligodendrocyte lineage cells 6-fold. With neuregulin present myelination is accelerated and increased, and NMDA receptor block reduces myelination to far below its level without neuregulin. Thus, a neuregulin-controlled switch enhances the myelination of active axons. In vivo, we demonstrate that remyelination after white matter damage is NMDA receptor-dependent. These data resolve controversies over the signalling regulating myelination and suggest novel roles for neuregulin in schizophrenia and in remyelination after white matter damage. Myelination acts as an insulator for neurons and as such is essential for normal brain function, ensuring fast neuronal communication. Oligodendrocytes are the cells that wrap their membrane around nerve cell axons to form the myelin sheath that enables fast action potential propagation. However, what determines whether an individual axon becomes myelinated remains unknown. We show that there are two distinct modes of myelination: one that is independent of neuronal activity and the release of the neurotransmitter glutamate and another that depends on nerve cell action potentials releasing glutamate, which then activates a class of glutamate receptor (NMDA receptors) on oligodendrocyte lineage cells. We find that the protein neuregulin switches oligodendrocytes between these two modes of myelination; neuregulin increases oligodendrocyte lineage cells' sensitivity to glutamate by increasing the current flowing through their glutamate receptors. With neuregulin present, myelination is accelerated and increased. Blocking NMDA receptors reduces the amount of myelination to far below its level without neuregulin. Thus, a neuregulin-controlled switch enhances the myelination of active axons. We also demonstrate that remyelination after white matter damage (as occurs in diseases, such as spinal cord injury and multiple sclerosis) is NMDA receptor-dependent. These data help us understand the signalling that regulates myelination and suggest the possible involvement of neuregulin in schizophrenia and in remyelination after white matter damage.
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Affiliation(s)
- Iben Lundgaard
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Aryna Luzhynskaya
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - John H. Stockley
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Zhen Wang
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Kimberley A. Evans
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Matthew Swire
- MRC Centre for Regenerative Medicine, Centre for Multiple Sclerosis Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Katrin Volbracht
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Hélène O. B. Gautier
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Robin J. M. Franklin
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Charles ffrench-Constant
- MRC Centre for Regenerative Medicine, Centre for Multiple Sclerosis Research, University of Edinburgh, Edinburgh, United Kingdom
| | - David Attwell
- Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom
| | - Ragnhildur T. Káradóttir
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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53
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Wang S, Young KM. White matter plasticity in adulthood. Neuroscience 2013; 276:148-60. [PMID: 24161723 DOI: 10.1016/j.neuroscience.2013.10.018] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 10/09/2013] [Accepted: 10/10/2013] [Indexed: 01/24/2023]
Abstract
CNS white matter is subject to a novel form of neural plasticity which has been termed "myelin plasticity". It is well established that oligodendrocyte generation and the addition of new myelin internodes continue throughout normal adulthood. These new myelin internodes maybe required for the de novo myelination of previously unmyelinated axons, myelin sheath replacement, or even myelin remodeling. Each process could alter axonal conduction velocity, but to what end? We review the changes that occur within the white matter over the lifetime, the known regulators and mediators of white matter plasticity in the mature CNS, and the physiological role this plasticity may play in CNS function.
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Affiliation(s)
- S Wang
- Menzies Research Institute Tasmania, University of Tasmania, Hobart 7000, Australia
| | - K M Young
- Menzies Research Institute Tasmania, University of Tasmania, Hobart 7000, Australia.
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54
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Xiao L, Hu C, Yang W, Guo D, Li C, Shen W, Liu X, Aijun H, Dan W, He C. NMDA receptor couples Rac1-GEF Tiam1 to direct oligodendrocyte precursor cell migration. Glia 2013; 61:2078-99. [PMID: 24123220 DOI: 10.1002/glia.22578] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 08/02/2013] [Accepted: 08/26/2013] [Indexed: 12/13/2022]
Affiliation(s)
- Lin Xiao
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Chun Hu
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Wenjing Yang
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Dazhi Guo
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Cui Li
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Weiran Shen
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Xiuyun Liu
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Huang Aijun
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Wang Dan
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Cheng He
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
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55
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Almeida RG, Lyons DA. On the resemblance of synapse formation and CNS myelination. Neuroscience 2013; 276:98-108. [PMID: 24035825 DOI: 10.1016/j.neuroscience.2013.08.062] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 08/29/2013] [Accepted: 08/29/2013] [Indexed: 10/26/2022]
Abstract
The myelination of axons in the central nervous system (CNS) is essential for nervous system formation, function and health. CNS myelination continues well into adulthood, but not all axons become myelinated. Unlike the peripheral nervous system, where we know of numerous axon-glial signals required for myelination, we have a poor understanding of the nature or identity of such molecules that regulate which axons are myelinated in the CNS. Recent studies have started to elucidate cell behavior during myelination in vivo and indicate that the choice of which axons are myelinated is made prior to myelin sheath generation. Here we propose that interactions between axons and the exploratory processes of oligodendrocyte precursor cells (OPCs) lead to myelination and may be similar to those between dendrites and axons that prefigure and lead to synapse formation. Indeed axons and OPCs form synapses with striking resemblance to those of neurons, suggesting a similar mode of formation. We discuss families of molecules with specific functions at different stages of synapse formation and address studies that implicate the same factors during axon-OPC synapse formation and myelination. We also address the possibility that the function of such synapses might directly regulate the myelinating behavior of oligodendrocyte processes in vivo. In the future it may be of benefit to consider these similarities when taking a candidate-based approach to dissect mechanisms of CNS myelination.
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Affiliation(s)
- R G Almeida
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, UK; MS Society Centre for Translational Research, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh EH16 4SB, UK.
| | - D A Lyons
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, UK; MS Society Centre for Translational Research, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh EH16 4SB, UK.
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56
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Tsutsui S, Stys PK. Metabolic injury to axons and myelin. Exp Neurol 2013; 246:26-34. [DOI: 10.1016/j.expneurol.2012.04.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 03/20/2012] [Accepted: 04/23/2012] [Indexed: 12/31/2022]
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Neurotransmitter-triggered transfer of exosomes mediates oligodendrocyte-neuron communication. PLoS Biol 2013; 11:e1001604. [PMID: 23874151 PMCID: PMC3706306 DOI: 10.1371/journal.pbio.1001604] [Citation(s) in RCA: 605] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 05/29/2013] [Indexed: 11/23/2022] Open
Abstract
Neuronal activity provokes myelinating oligodendrocytes to release exosomes by stimulation of ionotropic glutamate receptors, and that once released, these vesicles are internalized by neurons conveying neuroprotection. Reciprocal interactions between neurons and oligodendrocytes are not only crucial for myelination, but also for long-term survival of axons. Degeneration of axons occurs in several human myelin diseases, however the molecular mechanisms of axon-glia communication maintaining axon integrity are poorly understood. Here, we describe the signal-mediated transfer of exosomes from oligodendrocytes to neurons. These endosome-derived vesicles are secreted by oligodendrocytes and carry specific protein and RNA cargo. We show that activity-dependent release of the neurotransmitter glutamate triggers oligodendroglial exosome secretion mediated by Ca2+ entry through oligodendroglial NMDA and AMPA receptors. In turn, neurons internalize the released exosomes by endocytosis. Injection of oligodendroglia-derived exosomes into the mouse brain results in functional retrieval of exosome cargo in neurons. Supply of cultured neurons with oligodendroglial exosomes improves neuronal viability under conditions of cell stress. These findings indicate that oligodendroglial exosomes participate in a novel mode of bidirectional neuron-glia communication contributing to neuronal integrity. Brain function largely depends on the communication between electrically excitable neurons and surrounding glial cells. Myelinating oligodendrocytes are a type of brain cell that insulate major neuronal processes (axons) and help to sustainably maintain axonal health, which is poorly understood in molecular terms. Several cell types release microvesicles termed exosomes that include genetic information (primarily RNA) and can act as vehicles transferring specific cargo to target cells. Here, we demonstrate that exosomes secreted by oligodendrocytes in response to neuronal signals enter neurons to make their cargo functionally available to the neuronal metabolism. We revealed in cultured cells that exosome release from oligodendrocytes is triggered by the neurotransmitter glutamate through activation of ionotropic glutamate receptors. We also show that glial exosomes are internalized by neurons via an endocytic pathway. By modifying oligodendroglial exosomes with a reporter enzyme, we could demonstrate that the exosome cargo is recovered by target neurons in culture as well as in vivo after injection of exosomes into the mouse brain. Neurons challenged with stressful growth conditions were protected when treated with oligodendroglial exosomes. The study introduces a new concept of reciprocal cell communication in the nervous system and identifies the signal-mediated transfer of exosomes from oligodendrocytes to neurons contributing to the preservation of axonal health.
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58
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Benjamins JA, Nedelkoska L, Bealmear B, Lisak RP. ACTH protects mature oligodendroglia from excitotoxic and inflammation-related damage in vitro. Glia 2013; 61:1206-17. [PMID: 23832579 DOI: 10.1002/glia.22504] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 03/07/2013] [Indexed: 12/20/2022]
Abstract
Corticosteroids (CS) are widely employed to treat relapses in multiple sclerosis (MS). Endogenous ACTH is a 39-amino acid peptide that, among other functions, stimulates CS production. Exogenous ACTH 1-39 is used to treat MS relapses, presumably by stimulating endogenous CS production. However, unlike CS, ACTH binds to melanocortin receptors, found in the central nervous system (CNS) as well as on inflammatory cells. Since glia are implicated in MS and other neurodegenerative diseases, and oligodendroglia (OL) are more sensitive to injury than other glia, we characterized the protective effects of ACTH on OL in vitro without the confounding effects of CS. Rat brain cultures containing OL, astrocytes (AS), and microglia (MG) were incubated for 1 day with potentially cytotoxic agents with or without preincubation with ACTH 1-39. The cytotoxic agents killed 55-70% of mature OL, but caused little or no death of AS or MG at the concentrations used. ACTH protected OL from death induced by staurosporine, AMPA, NMDA, kainate, quinolinic acid, or reactive oxygen species, but did not protect against kynurenic acid or nitric oxide. The protective effects of ACTH were dose dependent, and decreased OL death induced by the different agents by 30-60% at 200 nM ACTH. We show for the first time that melanocortin 4 receptor is expressed on OL in addition to MG and AS. In summary, ACTH 1-39 protects OL in vitro from several excitotoxic and inflammation-related insults. ACTH may be activating melanocortin receptors on OL or alternately on AS or MG to prevent OL death.
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Affiliation(s)
- Joyce A Benjamins
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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59
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Zuchero JB, Barres BA. Intrinsic and extrinsic control of oligodendrocyte development. Curr Opin Neurobiol 2013; 23:914-20. [PMID: 23831087 DOI: 10.1016/j.conb.2013.06.005] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 06/11/2013] [Indexed: 11/24/2022]
Abstract
Oligodendrocytes (OLs) are the myelinating glia of the central nervous system. Myelin is essential for the rapid propagation of action potentials as well as for metabolic support of axons, and its loss in demyelinating diseases like multiple sclerosis has profound pathological consequences. The many steps in the development of OLs - from the specification of oligodendrocyte precursor cells (OPCs) during embryonic development to their differentiation into OLs that myelinate axons - are under tight regulation. Here we discuss recent advances in understanding how these steps of OL development are controlled intrinsically by transcription factors and chromatin remodeling and extrinsically by signaling molecules and neuronal activity. We also discuss how knowledge of these pathways is now allowing us to take steps toward generating patient-specific OPCs for disease modeling and myelin repair.
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Affiliation(s)
- J Bradley Zuchero
- Department of Neurobiology, Stanford University, Fairchild Building D205, 299 Campus Drive West, Stanford, CA 94305, United States.
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60
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Grasselli G, Rossi S, Musella A, Gentile A, Loizzo S, Muzio L, Di Sanza C, Errico F, Musumeci G, Haji N, Fresegna D, Sepman H, De Chiara V, Furlan R, Martino G, Usiello A, Mandolesi G, Centonze D. Abnormal NMDA receptor function exacerbates experimental autoimmune encephalomyelitis. Br J Pharmacol 2013; 168:502-17. [PMID: 22924679 DOI: 10.1111/j.1476-5381.2012.02178.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Revised: 08/04/2012] [Accepted: 08/13/2012] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE Glutamate transmission is dysregulated in both multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), the animal model of MS. A characteristic of EAE is increased glutamate transmission associated with up-regulation of AMPA receptors. However, little is known about the role of NMDA receptors in the synaptic modifications induced by EAE. EXPERIMENTAL APPROACH The contribution of NMDA receptors to the alterations of glutamate transmission and disease severity in EAE mice was assessed by means of neurophysiological, morphological, Western blot, metabolic and clinical score assessments. KEY RESULTS In our EAE mice, there was an NMDA receptor-dependent increase of glutamate release, associated with marked activation of the astroglia. Presynaptic NMDA receptors became overactive during EAE, increasing synaptic glutamate release by a mechanism dependent on voltage-gated sodium channels. By means of NAD(P)H autofluorescence analysis, we also found that EAE has a glutamate and NMDA receptor-dependent dysfunction of mitochondrial activity, which is known to contribute to the neurodegenerative damage of MS and EAE. Furthermore, pharmacological blockade of NMDA receptors in vivo ameliorated both synaptic transmission defects and of the clinical disease course of EAE mice, while EAE induced in mice with a genetically enhanced NMDA receptor signalling had opposite effects. CONCLUSIONS AND IMPLICATIONS Our data, showing both sensitization of NMDA receptors and their involvement in the progression of the EAE disease, supggest that pharmacological impairment of NMDA receptor signalling would be a component of a neuroprotection strategy in MS.
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Affiliation(s)
- G Grasselli
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), Università Tor Vergata, Rome, Italy
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61
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Abstract
The expression of the gut tumor suppressor gene adenomatous polyposis coli (Apc) and its role in the oligodendroglial lineage are poorly understood. We found that immunoreactive APC is transiently induced in the oligodendroglial lineage during both normal myelination and remyelination following toxin-induced, genetic, or autoimmune demyelination murine models. Using the Cre/loxP system to conditionally ablate APC from the oligodendroglial lineage, we determined that APC enhances proliferation of oligodendroglial progenitor cells (OPCs) and is essential for oligodendrocyte differentiation in a cell-autonomous manner. Biallelic Apc disruption caused translocation of β-catenin into the nucleus and upregulated β-catenin-mediated Wnt signaling in early postnatal but not adult oligodendroglial lineage cells. The results of conditional ablation of Apc or Ctnnb1 (the gene encoding β-catenin) and of simultaneous conditional ablation of Apc and Ctnnb1 revealed that β-catenin is dispensable for postnatal oligodendroglial differentiation, that Apc one-allele deficiency is not sufficient to dysregulate β-catenin-mediated Wnt signaling in oligodendroglial lineage cells, and that APC regulates oligodendrocyte differentiation through β-catenin-independent, as well as β-catenin-dependent, mechanisms. Gene ontology analysis of microarray data suggested that the β-catenin-independent mechanism involves APC regulation of the cytoskeleton, a result compatible with established APC functions in neural precursors and with our observation that Apc-deleted OPCs develop fewer, shorter processes in vivo. Together, our data support the hypothesis that APC regulates oligodendrocyte differentiation through both β-catenin-dependent and additional β-catenin-independent mechanisms.
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62
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Abstract
NG2 (nerve/glial antigen2)-expressing cells represent the largest population of postnatal progenitors in the central nervous system and have been classified as oligodendroglial progenitor cells, but the fate and function of these cells remain incompletely characterized. Previous studies have focused on characterizing these progenitors in the postnatal and adult subventricular zone and on analyzing the cellular and physiological properties of these cells in white and gray matter regions in the forebrain. In the present study, we examine the types of neural progeny generated by NG2 progenitors in the cerebellum by employing genetic fate mapping techniques using inducible Cre–Lox systems in vivo with two different mouse lines, the Plp-Cre-ERT2/Rosa26-EYFP and Olig2-Cre-ERT2/Rosa26-EYFP double-transgenic mice. Our data indicate that Olig2/Plp-positive NG2 cells display multipotential properties, primarily give rise to oligodendroglia but, surprisingly, also generate Bergmann glia, which are specialized glial cells in the cerebellum. The NG2+ cells also give rise to astrocytes, but not neurons. In addition, we show that glutamate signaling is involved in distinct NG2+ cell-fate/differentiation pathways and plays a role in the normal development of Bergmann glia. We also show an increase of cerebellar oligodendroglial lineage cells in response to hypoxic–ischemic injury, but the ability of NG2+ cells to give rise to Bergmann glia and astrocytes remains unchanged. Overall, our study reveals a novel Bergmann glia fate of Olig2/Plp-positive NG2 progenitors, demonstrates the differentiation of these progenitors into various functional glial cell types, and provides significant insights into the fate and function of Olig2/Plp-positive progenitor cells in health and disease.
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63
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Li C, Xiao L, Liu X, Yang W, Shen W, Hu C, Yang G, He C. A functional role of NMDA receptor in regulating the differentiation of oligodendrocyte precursor cells and remyelination. Glia 2013; 61:732-49. [PMID: 23440860 DOI: 10.1002/glia.22469] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 12/27/2012] [Indexed: 11/12/2022]
Abstract
Differentiation of oligodendrocyte precursor cells (OPCs) is the most important event for the myelination of central nervous system (CNS) axons during development and remyelination in demyelinating diseases, while the underlying molecular mechanisms remain largely unknown. Here we show that NMDA receptor (NMDAR) is a functional regulator of OPCs differentiation and remyelination. First, GluN1, GluN2A, and GluN2B subunits are expressed in oligodendrocyte lineage cells (OLs) in vitro and in vivo by immunostaining and Western blot analysis. Second, in a purified rat OPC culture system, NMDARs specially mediate OPCs differentiation by enhancing myelin proteins expression and the processes branching at the immature to mature oligodendrocyte transition analyzed by a serial of developmental stage-specific antigens. Moreover, pharmacological NMDAR antagonists or specific knockdown of GluN1 by RNA interference in OPCs prevents the differentiation induced by NMDA. NMDA can activate the mammalian target of rapamycin (mTOR) signal in OPCs and the pro-differentiation effect of NMDA is obstructed by the mTOR inhibitor rapamycin, suggesting NMDAR exerts its effect through mTOR-dependent mechanism. Furthermore, NMDA increases numbers of myelin segments in DRG-OPC cocultures. Finally, NMDAR specific antagonist MK801 delays remyelination in the cuprizone model examined by LFB-PAS, immunofluorescence and electron microscopy. This effect appears to result from inhibiting OPCs differentiation as more NG2(+) OPCs but less GST-π(+) mature oligodendrocytes are observed. Together, these results indicate that NMDAR plays a critical role in the regulation of OPCs differentiation in vitro and remyelination in cuprizone model which may provide potential target for the treatment of demyelination disease.
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Affiliation(s)
- Cui Li
- Institute of Neuroscience and MOE Key Laboratory of Molecular Neurobiology, Neuroscience Research Center of Changzheng Hospital, Second Military Medical University, Shanghai, 200433, China
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64
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Cao N, Yao ZX. Oligodendrocyte N-methyl-D-aspartate receptor signaling: insights into its functions. Mol Neurobiol 2013; 47:845-56. [PMID: 23345133 DOI: 10.1007/s12035-013-8408-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 01/13/2013] [Indexed: 12/21/2022]
Abstract
Myelination by oligodendrocytes facilitates rapid nerve conduction. Loss of oligodendrocytes and failure of myelination lead to nerve degeneration and numerous demyelinating white matter diseases. N-methyl-D-aspartate (NMDA) receptors, which are key regulators on neuron survival and functions, have been recently identified to express in oligodendrocytes, especially in the myelin sheath. NMDA receptor signaling in oligodendrocytes plays crucial roles in energy metabolism and myelination. In the present review, we highlight the subcellular location-specific impairment of excessive NMDA receptor signaling on oligodendrocyte energy metabolism in soma and myelin, and the mechanisms including Ca(2+) overload, acidotoxicity, mitochondria dysfunction, and impairment of respiratory chains. Conversely, physiological NMDA receptor signaling regulates differentiation and migration of oligodendrocytes. How can we use above knowledge to treat excitotoxic oligodendrocyte loss, congenital myelination deficiency, or postnatal demyelination? A thorough understanding of NMDA receptor signaling-mediated cellular events in oligodendrocytes at the pathophysiological level will no doubt aid in exploring effective therapeutic strategies for demyelinating white matter diseases.
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Affiliation(s)
- Nian Cao
- Department of Physiology, Third Military Medical University, Chongqing 400038, China
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65
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Moreno M, Guo F, Mills Ko E, Bannerman P, Soulika A, Pleasure D. Origins and significance of astrogliosis in the multiple sclerosis model, MOG peptide EAE. J Neurol Sci 2013; 333:55-9. [PMID: 23294494 DOI: 10.1016/j.jns.2012.12.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 12/05/2012] [Accepted: 12/10/2012] [Indexed: 12/31/2022]
Abstract
Astroglia, the most abundant cells in the human CNS, and even more prominent in multiple sclerosis patients, participate in CNS innate and adaptive immunity, and have been hypothesized to play an important role in multiple sclerosis progression. Experimental autoimmune encephalomyelitis elicited in mice by immunization with myelin oligodendrocyte glycoprotein peptide 35-55 provides a means by which to explore the genesis and disease significance of astrogliosis during a chronic immune-mediated CNS inflammatory/demyelinative disorder that, in its' pathological features, strongly resembles multiple sclerosis.
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Affiliation(s)
- Monica Moreno
- Institute for Pediatric Regenerative Research, UC Davis School of Medicine and Shriners Hospitals for Children Northern California, United States
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