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Peters C, Aberle T, Sock E, Brunner J, Küspert M, Hillgärtner S, Wüst HM, Wegner M. Voltage-Gated Ion Channels Are Transcriptional Targets of Sox10 during Oligodendrocyte Development. Cells 2024; 13:1159. [PMID: 38995010 PMCID: PMC11240802 DOI: 10.3390/cells13131159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Revised: 07/02/2024] [Accepted: 07/04/2024] [Indexed: 07/13/2024] Open
Abstract
The transcription factor Sox10 is an important determinant of oligodendroglial identity and influences oligodendroglial development and characteristics at various stages. Starting from RNA-seq data, we here show that the expression of several voltage-gated ion channels with known expression and important function in oligodendroglial cells depends upon Sox10. These include the Nav1.1, Cav2.2, Kv1.1, and Kir4.1 channels. For each of the four encoding genes, we found at least one regulatory region that is activated by Sox10 in vitro and at the same time bound by Sox10 in vivo. Cell-specific deletion of Sox10 in oligodendroglial cells furthermore led to a strong downregulation of all four ion channels in a mouse model and thus in vivo. Our study provides a clear functional link between voltage-gated ion channels and the transcriptional regulatory network in oligodendroglial cells. Furthermore, our study argues that Sox10 exerts at least some of its functions in oligodendrocyte progenitor cells, in myelinating oligodendrocytes, or throughout lineage development via these ion channels. By doing so, we present one way in which oligodendroglial development and properties can be linked to neuronal activity to ensure crosstalk between cell types during the development and function of the central nervous system.
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Affiliation(s)
- Christian Peters
- Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Tim Aberle
- Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Elisabeth Sock
- Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Jessica Brunner
- Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Melanie Küspert
- Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Simone Hillgärtner
- Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Hannah M Wüst
- Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Michael Wegner
- Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
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Gakare SG, Bhatt JM, Narasimhan KKS, Dravid SM. Glutamate delta-1 receptor regulates oligodendrocyte progenitor cell differentiation and myelination in normal and demyelinating conditions. PLoS One 2023; 18:e0294583. [PMID: 37983226 PMCID: PMC10659214 DOI: 10.1371/journal.pone.0294583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 11/05/2023] [Indexed: 11/22/2023] Open
Abstract
In this study, we investigated the role of glutamate delta 1 receptor (GluD1) in oligodendrocyte progenitor cell (OPC)-mediated myelination during basal (development) and pathophysiological (cuprizone-induced demyelination) conditions. Initially, we sought to determine the expression pattern of GluD1 in OPCs and found a significant colocalization of GluD1 puncta with neuron-glial antigen 2 (NG2, OPC marker) in the motor cortex and dorsal striatum. Importantly, we found that the ablation of GluD1 led to an increase in the number of myelin-associated glycoprotein (MAG+) cells in the corpus callosum and motor cortex at P40 without affecting the number of NG2+ OPCs, suggesting that GluD1 loss selectively facilitates OPC differentiation rather than proliferation. Further, deletion of GluD1 enhanced myelination in the corpus callosum and motor cortex, as indicated by increased myelin basic protein (MBP) staining at P40, suggesting that GluD1 may play an essential role in the developmental regulation of myelination during the critical window period. In contrast, in cuprizone-induced demyelination, we observed reduced MBP staining in the corpus callosum of GluD1 KO mice. Furthermore, cuprizone-fed GluD1 KO mice showed more robust motor deficits. Collectively, our results demonstrate that GluD1 plays a critical role in OPC regulation and myelination in normal and demyelinating conditions.
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Affiliation(s)
- Sukanya G. Gakare
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE, United States of America
| | - Jay M. Bhatt
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE, United States of America
| | - Kishore Kumar S. Narasimhan
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE, United States of America
| | - Shashank M. Dravid
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE, United States of America
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Afridi R, Rahman MH, Suk K. Implications of glial metabolic dysregulation in the pathophysiology of neurodegenerative diseases. Neurobiol Dis 2022; 174:105874. [PMID: 36154877 DOI: 10.1016/j.nbd.2022.105874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 08/28/2022] [Accepted: 09/21/2022] [Indexed: 11/16/2022] Open
Abstract
Glial cells are the most abundant cells of the brain, outnumbering neurons. These multifunctional cells are crucial for maintaining brain homeostasis by providing trophic and nutritional support to neurons, sculpting synapses, and providing an immune defense. Glia are highly plastic and undergo both structural and functional alterations in response to changes in the brain microenvironment. Glial phenotypes are intimately regulated by underlying metabolic machinery, which dictates the effector functions of these cells. Altered brain energy metabolism and chronic neuroinflammation are common features of several neurodegenerative diseases. Microglia and astrocytes are the major glial cells fueling the ongoing neuroinflammatory process, exacerbating neurodegeneration. Distinct metabolic perturbations in microglia and astrocytes, including altered carbohydrate, lipid, and amino acid metabolism have been documented in neurodegenerative diseases. These disturbances aggravate the neurodegenerative process by potentiating the inflammatory activation of glial cells. This review covers the recent advances in the molecular aspects of glial metabolic changes in the pathophysiology of neurodegenerative diseases. Finally, we discuss studies exploiting glial metabolism as a potential therapeutic avenue in neurodegenerative diseases.
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Affiliation(s)
- Ruqayya Afridi
- Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea; BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Sciences, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea
| | - Md Habibur Rahman
- Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea; Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Kyoungho Suk
- Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea; BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Sciences, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea; Brain Science and Engineering Institute, Kyungpook National University, Daegu 41944, Republic of Korea.
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4
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Gould E, Kim JH. SCN2A contributes to oligodendroglia excitability and development in the mammalian brain. Cell Rep 2021; 36:109653. [PMID: 34496232 PMCID: PMC8486143 DOI: 10.1016/j.celrep.2021.109653] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 05/04/2021] [Accepted: 08/12/2021] [Indexed: 01/21/2023] Open
Abstract
Spiking immature oligodendrocytes (OLs), referred to as spiking OLs, express voltage-activated Na+ channels (Nav) and K+ (Kv) channels, endowing a subpopulation of OLs with the ability to generate Nav-driven spikes. In this study, we investigate the molecular profile of spiking OLs, using single-cell transcriptomics paired with whole-cell patch-clamp recordings. SCN2A, which encodes the channel Nav1.2, is specifically expressed in spiking OLs in the brainstem and cerebellum, both in mice and in Olive baboons. Spiking OLs express lineage markers of OL progenitor cells (OPCs) and pre-myelinating OLs, indicating they belong to a transitional stage during differentiation. Deletion of SCN2A reduces the Nav current-expressing OL population and eliminates spiking OLs, indicating that SCN2A is essential for spiking in OLs. Deletion of SCN2A does not impact global OL proliferation but disrupts maturation of a subpopulation of OLs, suggesting that Nav1.2 is involved in heterogeneity in OL lineage cells and their development.
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Affiliation(s)
- Elizabeth Gould
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Jun Hee Kim
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center, San Antonio, TX 78229, USA,Lead contact,Correspondence:
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5
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Cytoskeletal Regulation of Oligodendrocyte Differentiation and Myelination. J Neurosci 2018; 37:7797-7799. [PMID: 28821599 DOI: 10.1523/jneurosci.1398-17.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 07/09/2017] [Accepted: 07/11/2017] [Indexed: 11/21/2022] Open
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6
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Brain Cell Type Specific Gene Expression and Co-expression Network Architectures. Sci Rep 2018; 8:8868. [PMID: 29892006 PMCID: PMC5995803 DOI: 10.1038/s41598-018-27293-5] [Citation(s) in RCA: 258] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 05/31/2018] [Indexed: 01/08/2023] Open
Abstract
Elucidating brain cell type specific gene expression patterns is critical towards a better understanding of how cell-cell communications may influence brain functions and dysfunctions. We set out to compare and contrast five human and murine cell type-specific transcriptome-wide RNA expression data sets that were generated within the past several years. We defined three measures of brain cell type-relative expression including specificity, enrichment, and absolute expression and identified corresponding consensus brain cell “signatures,” which were well conserved across data sets. We validated that the relative expression of top cell type markers are associated with proxies for cell type proportions in bulk RNA expression data from postmortem human brain samples. We further validated novel marker genes using an orthogonal ATAC-seq dataset. We performed multiscale coexpression network analysis of the single cell data sets and identified robust cell-specific gene modules. To facilitate the use of the cell type-specific genes for cell type proportion estimation and deconvolution from bulk brain gene expression data, we developed an R package, BRETIGEA. In summary, we identified a set of novel brain cell consensus signatures and robust networks from the integration of multiple datasets and therefore transcend limitations related to technical issues characteristic of each individual study.
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7
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Conditional Deletion of the L-Type Calcium Channel Cav1.2 in NG2-Positive Cells Impairs Remyelination in Mice. J Neurosci 2017; 37:10038-10051. [PMID: 28899915 DOI: 10.1523/jneurosci.1787-17.2017] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 08/29/2017] [Indexed: 12/15/2022] Open
Abstract
Exploring the molecular mechanisms that drive the maturation of oligodendrocyte progenitor cells (OPCs) during the remyelination process is essential to developing new therapeutic tools to intervene in demyelinating diseases such as multiple sclerosis. To determine whether L-type voltage-gated calcium channels (L-VGCCs) are required for OPC development during remyelination, we generated an inducible conditional knock-out mouse in which the L-VGCC isoform Cav1.2 was deleted in NG2-positive OPCs (Cav1.2KO). Using the cuprizone (CPZ) model of demyelination and mice of either sex, we establish that Cav1.2 deletion in OPCs leads to less efficient remyelination of the adult brain. Specifically, Cav1.2KO OPCs mature slower and produce less myelin than control oligodendrocytes during the recovery period after CPZ intoxication. This reduced remyelination was accompanied by an important decline in the number of myelinating oligodendrocytes and in the rate of OPC proliferation. Furthermore, during the remyelination phase of the CPZ model, the corpus callosum of Cav1.2KO animals presented a significant decrease in the percentage of myelinated axons and a substantial increase in the mean g-ratio of myelinated axons compared with controls. In addition, in a mouse line in which the Cav1.2KO OPCs were identified by a Cre reporter, we establish that Cav1.2KO OPCs display a reduced maturational rate through the entire remyelination process. These results suggest that Ca2+ influx mediated by L-VGCCs in oligodendroglial cells is necessary for normal remyelination and is an essential Ca2+ channel for OPC maturation during the remyelination of the adult brain.SIGNIFICANCE STATEMENT Ion channels implicated in oligodendrocyte differentiation and maturation may induce positive signals for myelin recovery. Voltage-gated Ca2+ channels (VGCCs) are important for normal myelination by acting at several critical steps during oligodendrocyte progenitor cell (OPC) development. To determine whether voltage Ca2+ entry is involved in oligodendrocyte differentiation and remyelination, we used a conditional knockout mouse for VGCCs in OPCs. Our results indicate that VGCCs can modulate oligodendrocyte maturation in the demyelinated brain and suggest that voltage-gated Ca2+ influx in OPCs is critical for remyelination. These findings could lead to novel approaches for obtaining a better understanding of the factors that control OPC maturation in order to stimulate this pool of progenitors to replace myelin in demyelinating diseases.
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8
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Boulanger JJ, Messier C. Oligodendrocyte progenitor cells are paired with GABA neurons in the mouse dorsal cortex: Unbiased stereological analysis. Neuroscience 2017; 362:127-140. [PMID: 28827179 DOI: 10.1016/j.neuroscience.2017.08.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 08/08/2017] [Accepted: 08/09/2017] [Indexed: 11/17/2022]
Abstract
Oligodendrocyte progenitor cells (OPC) are glial cells that differentiate into myelinating oligodendrocytes during early stages of post-natal life. However, OPCs persist beyond developmental myelination and represent an important population of cycling cells in the gray and white matter of the adult brain. While adult OPCs form unique territories that are maintained through self-avoidance, some cortical OPCs appear to position their cell body very close to that of a neuron, forming what are known as OPC-neuron pairs. We used unbiased systematic stereological analysis of the NG2-CreERTM:EYFP reporter mouse to determine that close to 170,000 OPC-neuron pairs can be found in the dorsal portion of the adult neocortex, with approximately 40% of OPCs and 4% of neurons in pairs. Through stereological analysis, we also determined that reference memory training does not change the prevalence of OPC-neuron pairs or the proportion of OPCs and neurons that form them. GABAergic agent administration did not affect the proportion of OPCs and neurons that can be found in pairs. However, the GABAB-receptor agonist baclofen and the GABAA receptor antagonist picrotoxin significantly increased the estimated number of pairs when compared to the control group and the GABAB-receptor antagonist (i.e. saclofen) group. Density of OPC-neuron pairs was increased by the GABAA receptor antagonist picrotoxin. Finally, histological analysis of OPC-neuron pairs suggested that in the dorsal portion of the cortex, GABAergic interneurons represent the most common neuronal component of the pairs, and that calbindin, calretinin and parvalbumin GABAergic interneurons found in the cortex take part in these pairs. Using previous estimates of the number of GABAergic neurons in the rodent cortex, we estimate that roughly one in four GABAergic neurons are paired with an OPC.
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9
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Snaidero N, Simons M. The logistics of myelin biogenesis in the central nervous system. Glia 2017; 65:1021-1031. [DOI: 10.1002/glia.23116] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 12/06/2016] [Accepted: 12/12/2016] [Indexed: 01/28/2023]
Affiliation(s)
- Nicolas Snaidero
- Institute of Neuronal Cell Biology, Technical University Munich; Munich 80805 Germany
| | - Mikael Simons
- Institute of Neuronal Cell Biology, Technical University Munich; Munich 80805 Germany
- German Center for Neurodegenerative Disease (DZNE); Munich 6250 Germany
- Cellular Neuroscience; Max Planck Institute of Experimental Medicine; Göttingen 37075 Germany
- Munich Cluster for Systems Neurology (SyNergy); Munich 81377 Germany
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10
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Dimou L, Gallo V. NG2-glia and their functions in the central nervous system. Glia 2015; 63:1429-51. [PMID: 26010717 DOI: 10.1002/glia.22859] [Citation(s) in RCA: 173] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/04/2015] [Indexed: 12/12/2022]
Abstract
In the central nervous system, NG2-glia represent a neural cell population that is distinct from neurons, astrocytes, and oligodendrocytes. While in the past the main role ascribed to these cells was that of progenitors for oligodendrocytes, in the last years it has become more obvious that they have further functions in the brain. Here, we will discuss some of the most current and highly debated issues regarding NG2-glia: Do these cells represent a heterogeneous population? Can they give rise to different progenies, and does this change under pathological conditions? How do they respond to injury or pathology? What is the role of neurotransmitter signaling between neurons and NG2-glia? We will first give an overview on the developmental origin of NG2-glia, and then discuss whether their distinct properties in different brain regions are the result of environmental influences, or due to intrinsic differences. We will then review and discuss their in vitro differentiation potential and in vivo lineage under physiological and pathological conditions, together with their electrophysiological properties in distinct brain regions and at different developmental stages. Finally, we will focus on their potential to be used as therapeutic targets in demyelinating and neurodegenerative diseases. Therefore, this review article will highlight the importance of NG2-glia not only in the healthy, but also in the diseased brain.
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Affiliation(s)
- L Dimou
- Physiological Genomics, Biomedical Center, Ludwig-Maximilians University, Munich, 80336, Germany.,Institute for Stem Cell Research, Helmholtz Zentrum Munich, Neuherberg, 85764, Germany
| | - V Gallo
- Center for Neuroscience Research, Children's Research Institute, Children's National Medical Center, Washington, District of Columbia
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11
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Thompson DM, Koppes AN, Hardy JG, Schmidt CE. Electrical stimuli in the central nervous system microenvironment. Annu Rev Biomed Eng 2015; 16:397-430. [PMID: 25014787 DOI: 10.1146/annurev-bioeng-121813-120655] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Electrical stimulation to manipulate the central nervous system (CNS) has been applied as early as the 1750s to produce visual sensations of light. Deep brain stimulation (DBS), cochlear implants, visual prosthetics, and functional electrical stimulation (FES) are being applied in the clinic to treat a wide array of neurological diseases, disorders, and injuries. This review describes the history of electrical stimulation of the CNS microenvironment; recent advances in electrical stimulation of the CNS, including DBS to treat essential tremor, Parkinson's disease, and depression; FES for the treatment of spinal cord injuries; and alternative electrical devices to restore vision and hearing via neuroprosthetics (retinal and cochlear implants). It also discusses the role of electrical cues during development and following injury and, importantly, manipulation of these endogenous cues to support regeneration of neural tissue.
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Affiliation(s)
- Deanna M Thompson
- Department of Biomedical Engineering and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180;
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12
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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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13
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van Wijngaarden P, Franklin RJM. Ageing stem and progenitor cells: implications for rejuvenation of the central nervous system. Development 2013; 140:2562-75. [PMID: 23715549 DOI: 10.1242/dev.092262] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The growing burden of the rapidly ageing global population has reinvigorated interest in the science of ageing and rejuvenation. Among organ systems, rejuvenation of the central nervous system (CNS) is arguably the most complex and challenging of tasks owing, among other things, to its startling structural and functional complexity and its restricted capacity for repair. Thus, the prospect of meaningful rejuvenation of the CNS has seemed an impossible goal; however, advances in stem cell science are beginning to challenge this assumption. This Review outlines these advances with a focus on ageing and rejuvenation of key endogenous stem and progenitor cell compartments in the CNS. Insights gleaned from studies of model organisms, chiefly rodents, will be considered in parallel with human studies.
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Affiliation(s)
- Peter van Wijngaarden
- Wellcome Trust-MRC Cambridge Stem Cell Institute and Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
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Malone M, Gary D, Yang IH, Miglioretti A, Houdayer T, Thakor N, McDonald J. Neuronal activity promotes myelination via a cAMP pathway. Glia 2013; 61:843-54. [PMID: 23554117 DOI: 10.1002/glia.22476] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 01/11/2013] [Indexed: 12/17/2022]
Abstract
Neuronal activity promotes myelination in vivo and in vitro. However, the molecular events that mediate activity-dependent myelination are not completely understood. Seven, daily 1 h sessions of patterned electrical stimulation (ESTIM) promoted myelin segment formation in mixed cultures of dorsal root ganglion (DRG) neurons and oligodendrocytes (OLs); the increase in myelination was frequency-dependent. Myelin segment formation was also enhanced following exposure of DRGs to ESTIM prior to OL addition, suggesting that ESTIM promotes myelination in a manner involving neuron-specific signaling. Cyclic adenosine monophosphate (cAMP) levels in DRGs were increased three-fold following ESTIM, and artificially increasing cAMP mimicked the ability of ESTIM to promote myelination. Alternatively, inhibiting the cAMP pathway suppressed ESTIM-induced myelination. We used compartmentalized, microfluidic platforms to isolate DRG soma from OLs and assessed cell-type specific effects of ESTIM on myelination. A selective increase or decrease in DRG cAMP levels resulted in enhanced or suppressed myelination, respectively. This work describes a novel role for the cAMP pathway in neurons that results in enhanced myelination.
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Affiliation(s)
- Misti Malone
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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15
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Properties and fate of oligodendrocyte progenitor cells in the corpus callosum, motor cortex, and piriform cortex of the mouse. J Neurosci 2012; 32:8173-85. [PMID: 22699898 DOI: 10.1523/jneurosci.0928-12.2012] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Oligodendrocyte progenitor cells (OPCs) in the postnatal mouse corpus callosum (CC) and motor cortex (Ctx) reportedly generate only oligodendrocytes (OLs), whereas those in the piriform cortex may also generate neurons. OPCs have also been subdivided based on their expression of voltage-gated ion channels, ability to respond to neuronal activity, and proliferative state. To determine whether OPCs in the piriform cortex have inherently different physiological properties from those in the CC and Ctx, we studied acute brain slices from postnatal transgenic mice in which GFP expression identifies OL lineage cells. We whole-cell patch clamped GFP-expressing (GFP(+)) cells within the CC, Ctx, and anterior piriform cortex (aPC) and used prelabeling with 5-ethynyl-2'-deoxyuridine (EdU) to assess cell proliferation. After recording, slices were immunolabeled and OPCs were defined by strong expression of NG2. NG2(+) OPCs in the white and gray matter proliferated and coexpressed PDGFRα and voltage-gated Na(+) channels (I(Na)). Approximately 70% of OPCs were capable of generating regenerative depolarizations. In addition to OLIG2(+) NG2(+) I(Na)(+) OPCs and OLIG2(+) NG2(neg) I(Na)(neg) OLs, we identified cells with low levels of NG2 limited to the soma or the base of some processes. These cells had a significantly reduced I(Na) and a reduced ability to incorporate EdU when compared with OPCs and probably correspond to early differentiating OLs. By combining EdU labeling and lineage tracing using Pdgfrα-CreER(T2) : R26R-YFP transgenic mice, we double labeled OPCs and traced their fate in the postnatal brain. These OPCs generated OLs but did not generate neurons in the aPC or elsewhere at any time that we examined.
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Abstract
Astrocytes are possibly the most numerous cells of the vertebrate central nervous system, yet a detailed characterization of their functions is still missing. One potential reason for the obscurity of astrocytic function is that they represent a diverse population of cells that all share some critical characteristics. In the CNS, astrocytes have been proposed to perform many functions. For example, they are supportive cells that provide guidance to newly formed migrating neurons and axons. They regulate the functions of endothelial cells at the blood brain barrier, provide nutrients, and maintain homeostasis including ionic balance within the CNS. More recently, dissecting the central role of astrocytes in mediating injury responses in the CNS, particularly the spinal cord, has become an area of considerable importance. The ability to culture-enriched populations of astrocytes has facilitated a detailed dissection of their potential roles in the developing and adult, normal, and injured brain and spinal cord. Most importantly, in vitro models have defined molecular signals that may mediate or regulate astrocyte functions and the capacity to modulate these signals may provide new opportunities for therapeutic intervention after spinal cord injury and other neural insults.
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Affiliation(s)
- Amber E Kerstetter
- Department of Neurosurgery, Center for Translational Neurosciences, Case Western Reserve University, Cleveland, OH, USA
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17
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Boda E, Viganò F, Rosa P, Fumagalli M, Labat-Gest V, Tempia F, Abbracchio MP, Dimou L, Buffo A. The GPR17 receptor in NG2 expressing cells: focus on in vivo cell maturation and participation in acute trauma and chronic damage. Glia 2011; 59:1958-73. [PMID: 21956849 DOI: 10.1002/glia.21237] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Accepted: 08/02/2011] [Indexed: 12/31/2022]
Abstract
NG2-expressing cells comprise a population of cycling precursors that can exit the cell cycle and differentiate into mature oligodendrocytes. As a whole, they display heterogeneous properties and behaviors that remain unresolved at the molecular level, although partly interpretable as distinct maturation stages. To address this issue, we analyzed the expression of the GPR17 receptor, recently shown to decorate NG2-expressing cells and to operate as an early sensor of brain damage, in immature and adult oligodendrocyte progenitors in the intact brain and after injury. In both the early postnatal and adult cerebral cortex, distinct GPR17 protein localizations and expression levels define different stages of oligodendroglial maturation, ranging from the precursor phase to the premyelinating phenotype. As soon as cells exit mitosis, a fraction of NG2-expressing cells displays accumulation of GPR17 protein in the Golgi apparatus. GPR17 expression is subsequently upregulated and distributed to processes of cells that stop dividing, progressively lose NG2 positivity and assume premyelinating features. Absence of colabeling with mature markers or myelin proteins indicates that GPR17 is downregulated when cells complete their final maturation. BrdU-based fate-mapping demonstrated that a significant fraction of newly generated oligodendrocyte progenitors transiently upregulates GPR17 during maturation. Importantly, we also found that GPR17 does not participate to the early reaction of NG2-expressing cells to damage, while it is induced at postacute stages after injury. These findings identify GPR17 as a marker for progenitor progression within the oligodendroglial lineage and highlight its participation to postacute reactivity of NG2 cells in different injury paradigms.
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Affiliation(s)
- Enrica Boda
- Department of Neuroscience, University of Turin, Turin, Italy
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Wake H, Lee PR, Fields RD. Control of local protein synthesis and initial events in myelination by action potentials. Science 2011; 333:1647-51. [PMID: 21817014 PMCID: PMC3482340 DOI: 10.1126/science.1206998] [Citation(s) in RCA: 453] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Formation of myelin, the electrical insulation on axons produced by oligodendrocytes, is controlled by complex cell-cell signaling that regulates oligodendrocyte development and myelin formation on appropriate axons. If electrical activity could stimulate myelin induction, then neurodevelopment and the speed of information transmission through circuits could be modified by neural activity. We find that release of glutamate from synaptic vesicles along axons of mouse dorsal root ganglion neurons in culture promotes myelin induction by stimulating formation of cholesterol-rich signaling domains between oligodendrocytes and axons, and increasing local synthesis of the major protein in the myelin sheath, myelin basic protein, through Fyn kinase-dependent signaling. This axon-oligodendrocyte signaling would promote myelination of electrically active axons to regulate neural development and function according to environmental experience.
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Affiliation(s)
- Hiroaki Wake
- Nervous System Development and Plasticity Section, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
| | - Philip R. Lee
- Nervous System Development and Plasticity Section, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
| | - R. Douglas Fields
- Nervous System Development and Plasticity Section, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
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Abstract
The RE1-silencing transcription factor (REST) represses the expression of neuronal-specific genes in non-neuronal cells by recruiting histone deacetylases (HDACs) and other histone modifying and chromatin remodeling proteins to the DNA. REST regulation of the expression of neuronal genes is required for the orderly developmental transition from a neuroepithelial stem cell to a functional neuron. Here, we examined the expression and function of REST in neonatal rat oligodendrocyte precursor cells (OPCs). OPCs develop from the same neuroepithelial stem cells as neurons, can be reprogrammed to act as neural stem-like cells in vitro, and require HDAC-mediated gene repression to develop into mature oligodendrocytes. We show that OPCs express functional REST protein and that REST interacts with several neuronal-specific genes whose expression is repressed in OPCs. REST transcript and protein expression increased fourfold during the first 48 h of oligodendrocyte differentiation. During this differentiation, the expression of RE1 containing neuronal genes further decreased as the transcription of oligodendrocyte-specific genes was activated. Expression of a dominant-negative form of REST in OPCs prevented the cells from developing into mature MBP-positive oligodendrocytes. Rather, the cells began to develop a neuronal phenotype characterized by increased expression of neuronal proteins, transcription factors, and cell-type-specific marker antigens. REST overexpression promoted the development of O4-positive pre-oligodendrocytes from OPCs. Together, these results show that REST function is required for the differentiation of OPCs into oligodendrocytes. By regulating the expression of neuronal genes, REST may also regulate the phenotypic plasticity of OPCs.
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Mangin JM, Gallo V. The curious case of NG2 cells: transient trend or game changer? ASN Neuro 2011; 3:e00052. [PMID: 21288204 PMCID: PMC3052864 DOI: 10.1042/an20110001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Accepted: 02/03/2011] [Indexed: 11/17/2022] Open
Abstract
It has been 10 years since the seminal work of Dwight Bergles and collaborators demonstrated that NG2 (nerve/glial antigen 2)-expressing oligodendrocyte progenitor cells (NG2 cells) receive functional glutamatergic synapses from neurons (Bergles et al., 2000), contradicting the old dogma that only neurons possess the complex and specialized molecular machinery necessary to receive synapses. While this surprising discovery may have been initially shunned as a novelty item of undefined functional significance, the study of neuron-to-NG2 cell neurotransmission has since become a very active and exciting field of research. Many laboratories have now confirmed and extended the initial discovery, showing for example that NG2 cells can also receive inhibitory GABAergic synapses (Lin and Bergles, 2004) or that neuron-to-NG2 cell synaptic transmission is a rather ubiquitous phenomenon that has been observed in all brain areas explored so far, including white matter tracts (Kukley et al., 2007; Ziskin et al., 2007; Etxeberria et al., 2010). Thus, while still being in its infancy, this field of research has already brought many surprising and interesting discoveries, and has become part of a continuously growing effort in neuroscience to re-evaluate the long underestimated role of glial cells in brain function (Barres, 2008). However, this area of research is now reaching an important milestone and its long-term significance will be defined by its ability to uncover the still elusive function of NG2 cells and their synapses in the brain, rather than by its sensational but transient successes at upsetting the old order established by neuronal physiology. To participate in the effort to facilitate such a transition, here we propose a critical review of the latest findings in the field of NG2 cell physiology--discussing how they inform us on the possible function(s) of NG2 cells in the brain--and we present some personal views on new directions the field could benefit from in order to achieve lasting significance.
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Key Words
- α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (ampar)
- nerve/glial antigen 2 (ng2) cells
- neuron
- oligodendrocyte progenitor cell (opc)
- postsynaptic density (psd)
- ampar, α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor
- cnp-gfp, c-type natriuretic peptide-green fluorescent protein
- cns, central nervous system
- egfp, enhanced green fluorescent protein
- epsc, excitatory postsynaptic current
- gaba, γ-aminobutyric acid
- gabaar, gaba type a receptor
- ltp, long-term potentiation
- mbp, maltose-binding protein
- ng2, nerve/glial antigen 2
- nmdar, n-methyl-d-aspartate receptor
- ol, oligodendrocyte lineage
- opc, oligodendrocyte progenitor cell
- pdgfrα, platelet-derived growth factor receptor α
- psd, postsynaptic density
- scp, schwann cell progenitor
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Affiliation(s)
- Jean-Marie Mangin
- Center for Neuroscience Research, Childrens National Medical Center, Washington, DC 20010, USA.
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In vivo intracellular recording suggests that gray matter astrocytes in mature cerebral cortex and hippocampus are electrophysiologically homogeneous. J Neurosci 2010; 30:3093-100. [PMID: 20181606 DOI: 10.1523/jneurosci.5065-09.2010] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Previous anatomical and in vitro electrophysiology studies suggest that astrocytes are heterogeneous in physiology, morphology, and biochemical content. However, the extent to which this diversity applies to in vivo conditions is largely unknown. To characterize and classify the physiological and morphological properties of cerebral cortical and hippocampal astrocytes in the intact brain, we performed in vivo intracellular recordings from single astrocytes using anesthetized mature rats. Astrocytes were classified based on their glial fibrillary acidic protein (GFAP) immunoreactivity and cell body locations. We analyzed morphometric measures such as the occupied volume and polarity, as well as physiological characteristics such as the mean membrane potential. These measurements did not show obvious segregation into subpopulations, suggesting that gray matter astrocytes in the cortex and hippocampus are composed of a homogeneous population in mature animals. The membrane potential of astrocytes in both cortex and hippocampus fluctuated within a few millivolts in the presence of spontaneous network activity. These membrane potential fluctuations of an astrocyte showed a significant variability that depended on the local field potential state and cell body location. We attribute the variability of the membrane potential fluctuations to local potassium concentration changes due to neuronal activity.
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Those enigmatic NG2 cells . . . . NEURON GLIA BIOLOGY 2010; 5:1. [PMID: 20422752 DOI: 10.1017/s1740925x09990445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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