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Uva L, Bruno G, de Curtis M. Activity-dependent extracellular potassium changes in unmyelinated versus myelinated areas in olfactory regions of the isolated female guinea-pig brain. Exp Neurol 2024; 379:114884. [PMID: 38992824 DOI: 10.1016/j.expneurol.2024.114884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 06/26/2024] [Accepted: 07/08/2024] [Indexed: 07/13/2024]
Abstract
The potassium released in the extracellular space during neuronal activity is rapidly removed by glia and neurons to maintain tissue homeostasis. Oligodendrocyte-derived myelin axonal coating contributes to potassium buffering and is therefore crucial to control brain excitability. We studied activity-dependent extracellular potassium ([K+]o) changes in the piriform cortex (PC), a region that features highly segregated bundles of myelinated and unmyelinated fibers. Four-aminopyridine (4AP; 50 μM) treatment or patterned high-frequency stimulations (hfST) were utilized to generate [K+]o changes measured with potassium-sensitive electrodes in the myelinated lateral olfactory tract (LOT), in the unmyelinated PC layer I and in the myelinated deep PC layers in the ex vivo isolated guinea-pig brain. Seizure-like events induced by 4AP are initiated by the abrupt [K+]o rise in the layer I formed by unmyelinated fibers (Uva et al., 2017). Larger [K+]o shifts occurred in unmyelinated layers compared to the myelinated LOT. LOT hfST that mimicks pre-seizure discharges also generated higher [K+]o changes in unmyelinated PC layer I than in LOT and deep PC layers. The treatment with the Kir4.1 potassium channel blocker BaCl2 (100 μM) enhanced the [K+]o changes generated by hfST in myelinated structures. Our data show that activity-dependent [K+]o changes are intrinsically different in myelinated vs unmyelinated cortical regions. The larger [K+]o shifts generated in unmyelinated structures may represent a vehicle for seizure generation.
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Affiliation(s)
- Laura Uva
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11/via Amadeo 42, Milano, Italy..
| | - Gaia Bruno
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11/via Amadeo 42, Milano, Italy.; Dipartimento di Biologia e Biotecnologia, via Forlanini, 6, Università di Pavia, 27100, Pavia, Italy..
| | - Marco de Curtis
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11/via Amadeo 42, Milano, Italy..
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2
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Mack AF, Bihlmaier R, Deffner F. Shifting from ependyma to choroid plexus epithelium and the changing expressions of aquaporin-1 and aquaporin-4. J Physiol 2024; 602:3097-3110. [PMID: 37975746 DOI: 10.1113/jp284196] [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: 06/24/2023] [Accepted: 10/30/2023] [Indexed: 11/19/2023] Open
Abstract
The cells of the choroid plexus (CP) epithelium are specialized ependymal cells (ECs) but have distinct properties. The CP cells and ECs form single-cell sheets contiguous to each other at a transitional zone. The CP is underlined by a basal lamina and has barrier properties, whereas the ECs do not. The basal lamina of the CP is continuous with the glia limitans superficialis and, consequently, the CP stroma is continuous with the meninges along entering blood vessels. The CP has previously been reported to express aquaporin-1 (AQP1) mostly apically, and ECs show mostly basolateral aquaporin-4 (AQP4) expression. Recent evidence in various systems has shown that in changing conditions the expression and distribution of AQP4 can be modified, involving phosphorylation and calmodulin-triggered translocation. Studies on the human CP revealed that AQP4 is also expressed in some CP cells, which is likely to be increased during ageing based on mouse data. Moreover, subependymal astrocytic processes in the ependyma-CP transition, forming a glial plate around blood vessels and facing the CP stroma, were strongly positive for AQP4. We propose that the increased AQP4 expression might be a compensatory mechanism for the observed reduction in CSF production in the ageing human brain. The high AQP4 density in the transition zone might facilitate the transport of water into and out of the CP stroma and serve as a drainage and clearing pathway for metabolites in the CNS.
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Affiliation(s)
- Andreas F Mack
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Ronja Bihlmaier
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Felix Deffner
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Freiburg, Freiburg, Germany
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3
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Looser ZJ, Faik Z, Ravotto L, Zanker HS, Jung RB, Werner HB, Ruhwedel T, Möbius W, Bergles DE, Barros LF, Nave KA, Weber B, Saab AS. Oligodendrocyte-axon metabolic coupling is mediated by extracellular K + and maintains axonal health. Nat Neurosci 2024; 27:433-448. [PMID: 38267524 PMCID: PMC10917689 DOI: 10.1038/s41593-023-01558-3] [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: 11/08/2022] [Accepted: 12/13/2023] [Indexed: 01/26/2024]
Abstract
The integrity of myelinated axons relies on homeostatic support from oligodendrocytes (OLs). To determine how OLs detect axonal spiking and how rapid axon-OL metabolic coupling is regulated in the white matter, we studied activity-dependent calcium (Ca2+) and metabolite fluxes in the mouse optic nerve. We show that fast axonal spiking triggers Ca2+ signaling and glycolysis in OLs. OLs detect axonal activity through increases in extracellular potassium (K+) concentrations and activation of Kir4.1 channels, thereby regulating metabolite supply to axons. Both pharmacological inhibition and OL-specific inactivation of Kir4.1 reduce the activity-induced axonal lactate surge. Mice lacking oligodendroglial Kir4.1 exhibit lower resting lactate levels and altered glucose metabolism in axons. These early deficits in axonal energy metabolism are associated with late-onset axonopathy. Our findings reveal that OLs detect fast axonal spiking through K+ signaling, making acute metabolic coupling possible and adjusting the axon-OL metabolic unit to promote axonal health.
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Affiliation(s)
- Zoe J Looser
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland
| | - Zainab Faik
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland
| | - Luca Ravotto
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland
| | - Henri S Zanker
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland
| | - Ramona B Jung
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Hauke B Werner
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Torben Ruhwedel
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Wiebke Möbius
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Dwight E Bergles
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA
| | - L Felipe Barros
- Centro de Estudios Científicos (CECs), Valdivia, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia, Chile
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland
| | - Aiman S Saab
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland.
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4
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Abstract
Epilepsy is a neurological disorder caused by the pathological hyper-synchronization of neuronal discharges. The fundamental research of epilepsy mechanisms and the targets of drug design options for its treatment have focused on neurons. However, approximately 30% of patients suffering from epilepsy show resistance to standard anti-epileptic chemotherapeutic agents while the symptoms of the remaining 70% of patients can be alleviated but not completely removed by the current medications. Thus, new strategies for the treatment of epilepsy are in urgent demand. Over the past decades, with the increase in knowledge on the role of glia in the genesis and development of epilepsy, glial cells are receiving renewed attention. In a normal brain, glial cells maintain neuronal health and in partnership with neurons regulate virtually every aspect of brain function. In epilepsy, however, the supportive roles of glial cells are compromised, and their interaction with neurons is altered, which disrupts brain function. In this review, we will focus on the role of glia-related processes in epileptogenesis and their contribution to abnormal neuronal activity, with the major focus on the dysfunction of astroglial potassium channels, water channels, gap junctions, glutamate transporters, purinergic signaling, synaptogenesis, on the roles of microglial inflammatory cytokines, microglia-astrocyte interactions in epilepsy, and on the oligodendroglial potassium channels and myelin abnormalities in the epileptic brain. These recent findings suggest that glia should be considered as the promising next-generation targets for designing anti-epileptic drugs that may improve epilepsy and drug-resistant epilepsy.
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Affiliation(s)
- Weida Shen
- Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang Province, China
| | - Jelena Bogdanović Pristov
- Department of Life Sciences, University of Belgrade, Institute for Multidisciplinary Research, Belgrade, Serbia
| | - Paola Nobili
- Institute of Functional Genomics (IGF), University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Ljiljana Nikolić
- Department of Neurophysiology, Institute for Biological Research Siniša Stanković, National Institute of Republic of Serbia, University of Belgrade, Belgrade, Serbia
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Abrams CK. Mechanisms of Diseases Associated with Mutation in GJC2/Connexin 47. Biomolecules 2023; 13:biom13040712. [PMID: 37189458 DOI: 10.3390/biom13040712] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 04/03/2023] [Accepted: 04/04/2023] [Indexed: 05/17/2023] Open
Abstract
Connexins are members of a family of integral membrane proteins that provide a pathway for both electrical and metabolic coupling between cells. Astroglia express connexin 30 (Cx30)-GJB6 and Cx43-GJA1, while oligodendroglia express Cx29/Cx31.3-GJC3, Cx32-GJB1, and Cx47-GJC2. Connexins organize into hexameric hemichannels (homomeric if all subunits are identical or heteromeric if one or more differs). Hemichannels from one cell then form cell-cell channels with a hemichannel from an apposed cell. (These are termed homotypic if the hemichannels are identical and heterotypic if the hemichannels differ). Oligodendrocytes couple to each other through Cx32/Cx32 or Cx47/Cx47 homotypic channels and they couple to astrocytes via Cx32/Cx30 or Cx47/Cx43 heterotypic channels. Astrocytes couple via Cx30/Cx30 and Cx43/Cx43 homotypic channels. Though Cx32 and Cx47 may be expressed in the same cells, all available data suggest that Cx32 and Cx47 cannot interact heteromerically. Animal models wherein one or in some cases two different CNS glial connexins have been deleted have helped to clarify the role of these molecules in CNS function. Mutations in a number of different CNS glial connexin genes cause human disease. Mutations in GJC2 lead to three distinct phenotypes, Pelizaeus Merzbacher like disease, hereditary spastic paraparesis (SPG44) and subclinical leukodystrophy.
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Affiliation(s)
- Charles K Abrams
- Department of Neurology and Rehabilitation, University of Illinois at Chicago College of Medicine, Chicago, IL 60612, USA
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6
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Köhler S, Winkler U, Junge T, Lippmann K, Eilers J, Hirrlinger J. Gray and white matter astrocytes differ in basal metabolism but respond similarly to neuronal activity. Glia 2023; 71:229-244. [PMID: 36063073 DOI: 10.1002/glia.24268] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 07/12/2022] [Accepted: 08/22/2022] [Indexed: 11/10/2022]
Abstract
Astrocytes are a heterogeneous population of glial cells in the brain, which adapt their properties to the requirements of the local environment. Two major groups of astrocytes are protoplasmic astrocytes residing in gray matter as well as fibrous astrocytes of white matter. Here, we compared the energy metabolism of astrocytes in the cortex and corpus callosum as representative gray matter and white matter regions, in acute brain slices taking advantage of genetically encoded fluorescent nanosensors for the NADH/NAD+ redox ratio and for ATP. Astrocytes of the corpus callosum presented a more reduced basal NADH/NAD+ redox ratio, and a lower cytosolic concentration of ATP compared to cortical astrocytes. In cortical astrocytes, the neurotransmitter glutamate and increased extracellular concentrations of K+ , typical correlates of neuronal activity, induced a more reduced NADH/NAD+ redox ratio. While application of glutamate decreased [ATP], K+ as well as the combination of glutamate and K+ resulted in an increase of ATP levels. Strikingly, a very similar regulation of metabolism by K+ and glutamate was observed in astrocytes in the corpus callosum. Finally, strong intrinsic neuronal activity provoked by application of bicuculline and withdrawal of Mg2+ caused a shift of the NADH/NAD+ redox ratio to a more reduced state as well as a slight reduction of [ATP] in gray and white matter astrocytes. In summary, the metabolism of astrocytes in cortex and corpus callosum shows distinct basal properties, but qualitatively similar responses to neuronal activity, probably reflecting the different environment and requirements of these brain regions.
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Affiliation(s)
- Susanne Köhler
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - Ulrike Winkler
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - Tabea Junge
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - Kristina Lippmann
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - Jens Eilers
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - Johannes Hirrlinger
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany.,Department of Neurogenetics, Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
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7
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Astrocytes as Context for the Involvement of Myelin and Nodes of Ranvier in the Pathophysiology of Depression and Stress-Related Disorders. JOURNAL OF PSYCHIATRY AND BRAIN SCIENCE 2023; 8:e230001. [PMID: 36866235 PMCID: PMC9976698 DOI: 10.20900/jpbs.20230001] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
Astrocytes, despite some shared features as glial cells supporting neuronal function in gray and white matter, participate and adapt their morphology and neurochemistry in a plethora of distinct regulatory tasks in specific neural environments. In the white matter, a large proportion of the processes branching from the astrocytes' cell bodies establish contacts with oligodendrocytes and the myelin they form, while the tips of many astrocyte branches closely associate with nodes of Ranvier. Stability of myelin has been shown to greatly depend on astrocyte-to-oligodendrocyte communication, while the integrity of action potentials that regenerate at nodes of Ranvier has been shown to depend on extracellular matrix components heavily contributed by astrocytes. Several lines of evidence are starting to show that in human subjects with affective disorders and in animal models of chronic stress there are significant changes in myelin components, white matter astrocytes and nodes of Ranvier that have direct relevance to connectivity alterations in those disorders. Some of these changes involve the expression of connexins supporting astrocyte-to-oligodendrocyte gap junctions, extracellular matrix components produced by astrocytes around nodes of Ranvier, specific types of astrocyte glutamate transporters, and neurotrophic factors secreted by astrocytes that are involved in the development and plasticity of myelin. Future studies should further examine the mechanisms responsible for those changes in white matter astrocytes, their putative contribution to pathological connectivity in affective disorders, and the possibility of leveraging that knowledge to design new therapies for psychiatric disorders.
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Jiang Y, Yao D, Zhou J, Tan Y, Huang H, Wang M, Chang X, Duan M, Luo C. Characteristics of disrupted topological organization in white matter functional connectome in schizophrenia. Psychol Med 2022; 52:1333-1343. [PMID: 32880241 DOI: 10.1017/s0033291720003141] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Neuroimaging characteristics have demonstrated disrupted functional organization in schizophrenia (SZ), involving large-scale networks within grey matter (GM). However, previous studies have ignored the role of white matter (WM) in supporting brain function. METHODS Using resting-state functional MRI and graph theoretical approaches, we investigated global topological disruptions of large-scale WM and GM networks in 93 SZ patients and 122 controls. Six global properties [clustering coefficient (Cp), shortest path length (Lp), local efficiency (Eloc), small-worldness (σ), hierarchy (β) and synchronization (S) and three nodal metrics [nodal degree (Knodal), nodal efficiency (Enodal) and nodal betweenness (Bnodal)] were utilized to quantify the topological organization in both WM and GM networks. RESULTS At the network level, both WM and GM networks exhibited reductions in Eloc, Cp and S in SZ. The SZ group showed reduced σ and β only for the WM network. Furthermore, the Cp, Eloc and S of the WM network were negatively correlated with negative symptoms in SZ. At the nodal level, the SZ showed nodal disturbances in the corpus callosum, optic radiation, posterior corona radiata and tempo-occipital WM tracts. For GM, the SZ manifested increased nodal centralities in frontoparietal regions and decreased nodal centralities in temporal regions. CONCLUSIONS These findings provide the first evidence for abnormal global topological properties in SZ from the perspective of a substantial whole brain, including GM and WM. Nodal centralities enhance GM areas, along with a reduction in adjacent WM, suggest that WM functional alterations may be compensated for adjacent GM impairments in SZ.
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Affiliation(s)
- Yuchao Jiang
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, P. R. China
- High-Field Magnetic Resonance Brain Imaging Key Laboratory of Sichuan Province, School of life Science and technology, University of Electronic Science and Technology of China, Chengdu, P. R. China
| | - Dezhong Yao
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, P. R. China
- Research Unit of NeuroInformation, Chinese Academy of Medical Sciences, 2019RU035, Chengdu, P. R. China
- School of Electrical Engineering, Zhengzhou University, Zhengzhou, P. R. China
| | - Jingyu Zhou
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, P. R. China
- High-Field Magnetic Resonance Brain Imaging Key Laboratory of Sichuan Province, School of life Science and technology, University of Electronic Science and Technology of China, Chengdu, P. R. China
| | - Yue Tan
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, P. R. China
| | - Huan Huang
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, P. R. China
| | - MeiLin Wang
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, P. R. China
| | - Xin Chang
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, P. R. China
- High-Field Magnetic Resonance Brain Imaging Key Laboratory of Sichuan Province, School of life Science and technology, University of Electronic Science and Technology of China, Chengdu, P. R. China
| | - Mingjun Duan
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, P. R. China
- Department of Psychiatry, Chengdu Mental Health Center, Chengdu, P. R. China
| | - Cheng Luo
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, P. R. China
- High-Field Magnetic Resonance Brain Imaging Key Laboratory of Sichuan Province, School of life Science and technology, University of Electronic Science and Technology of China, Chengdu, P. R. China
- Research Unit of NeuroInformation, Chinese Academy of Medical Sciences, 2019RU035, Chengdu, P. R. China
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Hösli L, Binini N, Ferrari KD, Thieren L, Looser ZJ, Zuend M, Zanker HS, Berry S, Holub M, Möbius W, Ruhwedel T, Nave KA, Giaume C, Weber B, Saab AS. Decoupling astrocytes in adult mice impairs synaptic plasticity and spatial learning. Cell Rep 2022; 38:110484. [PMID: 35263595 DOI: 10.1016/j.celrep.2022.110484] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/20/2021] [Accepted: 02/14/2022] [Indexed: 12/16/2022] Open
Abstract
The mechanisms by which astrocytes modulate neural homeostasis, synaptic plasticity, and memory are still poorly explored. Astrocytes form large intercellular networks by gap junction coupling, mainly composed of two gap junction channel proteins, connexin 30 (Cx30) and connexin 43 (Cx43). To circumvent developmental perturbations and to test whether astrocytic gap junction coupling is required for hippocampal neural circuit function and behavior, we generate and study inducible, astrocyte-specific Cx30 and Cx43 double knockouts. Surprisingly, disrupting astrocytic coupling in adult mice results in broad activation of astrocytes and microglia, without obvious signs of pathology. We show that hippocampal CA1 neuron excitability, excitatory synaptic transmission, and long-term potentiation are significantly affected. Moreover, behavioral inspection reveals deficits in sensorimotor performance and a complete lack of spatial learning and memory. Together, our findings establish that astrocytic connexins and an intact astroglial network in the adult brain are vital for neural homeostasis, plasticity, and spatial cognition.
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Affiliation(s)
- Ladina Hösli
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, 8057 Zurich, Switzerland
| | - Noemi Binini
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, 8057 Zurich, Switzerland
| | - Kim David Ferrari
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, 8057 Zurich, Switzerland
| | - Laetitia Thieren
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, 8057 Zurich, Switzerland
| | - Zoe J Looser
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, 8057 Zurich, Switzerland
| | - Marc Zuend
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, 8057 Zurich, Switzerland
| | - Henri S Zanker
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, 8057 Zurich, Switzerland
| | - Stewart Berry
- Brain Research Institute, University of Zurich, 8057 Zurich, Switzerland
| | - Martin Holub
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, 8057 Zurich, Switzerland
| | - Wiebke Möbius
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Torben Ruhwedel
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Klaus-Armin Nave
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Christian Giaume
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, 75231 Paris Cedex 05, France
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, 8057 Zurich, Switzerland.
| | - Aiman S Saab
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, 8057 Zurich, Switzerland.
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10
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Çavdar S, Köse B, Özkan M, Sur Erdem İ. Comparison of astrocytes and gap junction proteins in the white matter of genetic absence epileptic and control rats: an experimental study. Neurol Res 2022; 44:708-718. [DOI: 10.1080/01616412.2022.2039527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Safiye Çavdar
- Department of Anatomy, Koç University School of Medicine, Istanbul, Turkey
| | - Büşra Köse
- Department of Anatomy, Koç University School of Medicine, Istanbul, Turkey
| | - Mazhar Özkan
- Department of Anatomy, Tekirdağ Namık Kemal University School of Medicine, Istanbul, Turkey
| | - İlknur Sur Erdem
- Department of Molecular Biology, Koç University School of Medicine, Istanbul, Turkey
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11
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Cibelli A, Stout R, Timmermann A, de Menezes L, Guo P, Maass K, Seifert G, Steinhäuser C, Spray DC, Scemes E. Cx43 carboxyl terminal domain determines AQP4 and Cx30 endfoot organization and blood brain barrier permeability. Sci Rep 2021; 11:24334. [PMID: 34934080 PMCID: PMC8692511 DOI: 10.1038/s41598-021-03694-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 12/06/2021] [Indexed: 11/08/2022] Open
Abstract
The neurovascular unit (NVU) consists of cells intrinsic to the vessel wall, the endothelial cells and pericytes, and astrocyte endfeet that surround the vessel but are separated from it by basement membrane. Endothelial cells are primarily responsible for creating and maintaining blood-brain-barrier (BBB) tightness, but astrocytes contribute to the barrier through paracrine signaling to the endothelial cells and by forming the glia limitans. Gap junctions (GJs) between astrocyte endfeet are composed of connexin 43 (Cx43) and Cx30, which form plaques between cells. GJ plaques formed of Cx43 do not diffuse laterally in the plasma membrane and thus potentially provide stable organizational features to the endfoot domain, whereas GJ plaques formed of other connexins and of Cx43 lacking a large portion of its cytoplasmic carboxyl terminus are quite mobile. In order to examine the organizational features that immobile GJs impose on the endfoot, we have used super-resolution confocal microscopy to map number and sizes of GJ plaques and aquaporin (AQP)-4 channel clusters in the perivascular endfeet of mice in which astrocyte GJs (Cx30, Cx43) were deleted or the carboxyl terminus of Cx43 was truncated. To determine if BBB integrity was compromised in these transgenic mice, we conducted perfusion studies under elevated hydrostatic pressure using horseradish peroxide as a molecular probe enabling detection of micro-hemorrhages in brain sections. These studies revealed that microhemorrhages were more numerous in mice lacking Cx43 or its carboxyl terminus. In perivascular domains of cerebral vessels, we found that density of Cx43 GJs was higher in the truncation mutant, while GJ size was smaller. Density of perivascular particles formed by AQP4 and its extended isoform AQP4ex was inversely related to the presence of full length Cx43, whereas the ratio of sizes of the particles of the AQP4ex isoform to total AQP4 was directly related to the presence of full length Cx43. Confocal analysis showed that Cx43 and Cx30 were substantially colocalized in astrocyte domains near vasculature of truncation mutant mice. These results showing altered distribution of some astrocyte nexus components (AQP4 and Cx30) in Cx43 null mice and in a truncation mutant, together with leakier cerebral vasculature, support the hypothesis that localization and mobility of gap junction proteins and their binding partners influences organization of astrocyte endfeet which in turn impacts BBB integrity of the NVU.
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Affiliation(s)
- Antonio Cibelli
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Randy Stout
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- New York Institute of Technology College of Osteopathic Medicine, Old Westbury, NY, USA
| | - Aline Timmermann
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Laura de Menezes
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Insitute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Peng Guo
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Cellular Imaging Core Facility, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Karen Maass
- Cardiovascular Research Center, NYU Grossman School of Medicine, New York, NY, USA
| | - Gerald Seifert
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - David C Spray
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA.
| | - Eliana Scemes
- Department of Anatomy and Cell Biology, New York Medical College, Valhalla, NY, 10595, USA.
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12
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Abstract
Although the glymphatic system hypothesis is highly popular, it also lacks certain details. In this paper, an attempt was made to present a more clearly defined hypothesis, which is consistent with the past experiment results. The new hypothesis consists of (1) water flux in the brain parenchyma, (2) water and solutes pathway of the perivascular space, and (3) maintenance of this pathway by the network of astrocytes.
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Affiliation(s)
- Koichi Oshio
- Department of Diagnostic Radiology, Keio University School of Medicine, Tokyo, Japan,Corresponding author: Department of Radiogy, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
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13
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Lajoso W, Flower G, Giacco V, Kaul A, La Mache C, Brăban A, Roxas A, Hamilton NB. Transient Receptor Potential Ankyrin-1 (TRPA1) Block Protects against Loss of White Matter Function during Ischaemia in the Mouse Optic Nerve. Pharmaceuticals (Basel) 2021; 14:ph14090909. [PMID: 34577609 PMCID: PMC8469017 DOI: 10.3390/ph14090909] [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: 08/12/2021] [Revised: 09/02/2021] [Accepted: 09/03/2021] [Indexed: 11/28/2022] Open
Abstract
Oligodendrocytes produce myelin, which provides insulation to axons and speeds up neuronal transmission. In ischaemic conditions, myelin is damaged, resulting in mental and physical disabilities. Recent evidence suggests that oligodendrocyte damage during ischaemia can be mediated by Transient Receptor Potential Ankyrin-1 (TRPA1), whose activation raises intracellular Ca2+ concentrations and damages compact myelin. Here, we show that TRPA1 is constitutively active in oligodendrocytes and the optic nerve, as the specific TRPA1 antagonist, A-967079, decreases basal oligodendrocyte Ca2+ concentrations and increases the size of the compound action potential (CAP). Conversely, TRPA1 agonists reduce the size of the optic nerve CAP in an A-967079-sensitive manner. These results indicate that glial TRPA1 regulates neuronal excitability in the white matter under physiological as well as pathological conditions. Importantly, we find that inhibition of TRPA1 prevents loss of CAPs during oxygen and glucose deprivation (OGD) and improves the recovery. TRPA1 block was effective when applied before, during, or after OGD, indicating that the TRPA1-mediated damage is occurring during both ischaemia and recovery, but importantly, that therapeutic intervention is possible after the ischaemic insult. These results indicate that TRPA1 has an important role in the brain, and that its block may be effective in treating many white matter diseases.
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14
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Abrams CK, Flores-Obando RE, Dungan GD, Cherepanova E, Freidin MM. Investigating oligodendrocyte connexins: Heteromeric interactions between Cx32 and mutant or wild-type forms of Cx47 do not contribute to or modulate gap junction function. Glia 2021; 69:1882-1896. [PMID: 33835612 DOI: 10.1002/glia.23999] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/16/2021] [Accepted: 03/17/2021] [Indexed: 11/11/2022]
Abstract
Oligodendrocytes express two gap junction forming connexins, connexin 32 (Cx32) and Cx47; therefore, formation of heteromeric channels containing both Cx47 and Cx32 monomers might occur. Mutations in Cx47 cause both Pelizaeus-Merzbacher-like disease Type 1 (PMLD1) and hereditary spastic paraparesis Type 44 (SPG44) and heteromer formation between these mutants and Cx32 may contribute to the pathogenesis of these disorders. Here, we utilized electrophysiological and antibody-based techniques to examine this possibility. When cells expressing both Cx32 and Cx47 were paired with cells expressing either Cx32 or Cx47, properties were indistinguishable from those produced by cells expressing homotypic Cx32 or Cx47 channels. Similarly, pairing cells expressing both Cx32 and Cx47 with cells expressing Cx30 or Cx43 produced channels indistinguishable from heterotypic Cx32/Cx30 or Cx47/Cx43 channels, respectively. The same assessments were performed on cells expressing Cx32 and four mutant forms of Cx47 (p.I33M associated with SPG44 or p.P87S, p.Y269D or p.M283T associated with PMLD1). None of these mutants showed a functional effect on Cx32. Immunostained cells co-expressing Cx32WT (wild type) and Cx47WT showed a Pearson correlation coefficient close to zero, suggesting that any overlap was due to chance. p.Y269D showed a statistically significant negative correlation with Cx32, suggesting that Cx32 and this mutant overlap less than expected by chance. Co-immunoprecipitation of Cx32 with Cx47WT and mutants show only very low levels of co-immunoprecipitated protein. Overall, our data suggest that interactions between PMLD1 or SPG44 mutants and Cx32 gap junctions do not contribute to the pathogenesis of these disorders.
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Affiliation(s)
- Charles K Abrams
- Department of Neurology and Rehabilitation, University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
- Department of Neurology, SUNY Downstate Medical Center, Brooklyn, New York, USA
| | | | - Gabriel D Dungan
- Department of Neurology and Rehabilitation, University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
| | - Elina Cherepanova
- Department of Neurology, SUNY Downstate Medical Center, Brooklyn, New York, USA
| | - Mona M Freidin
- Department of Neurology and Rehabilitation, University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA
- Department of Neurology, SUNY Downstate Medical Center, Brooklyn, New York, USA
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15
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Duncan GJ, Simkins TJ, Emery B. Neuron-Oligodendrocyte Interactions in the Structure and Integrity of Axons. Front Cell Dev Biol 2021; 9:653101. [PMID: 33763430 PMCID: PMC7982542 DOI: 10.3389/fcell.2021.653101] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/15/2021] [Indexed: 12/12/2022] Open
Abstract
The myelination of axons by oligodendrocytes is a highly complex cell-to-cell interaction. Oligodendrocytes and axons have a reciprocal signaling relationship in which oligodendrocytes receive cues from axons that direct their myelination, and oligodendrocytes subsequently shape axonal structure and conduction. Oligodendrocytes are necessary for the maturation of excitatory domains on the axon including nodes of Ranvier, help buffer potassium, and support neuronal energy metabolism. Disruption of the oligodendrocyte-axon unit in traumatic injuries, Alzheimer's disease and demyelinating diseases such as multiple sclerosis results in axonal dysfunction and can culminate in neurodegeneration. In this review, we discuss the mechanisms by which demyelination and loss of oligodendrocytes compromise axons. We highlight the intra-axonal cascades initiated by demyelination that can result in irreversible axonal damage. Both the restoration of oligodendrocyte myelination or neuroprotective therapies targeting these intra-axonal cascades are likely to have therapeutic potential in disorders in which oligodendrocyte support of axons is disrupted.
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Affiliation(s)
- Greg J. Duncan
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States
| | - Tyrell J. Simkins
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States
- Vollum Institute, Oregon Health & Science University, Portland, OR, United States
- Department of Neurology, VA Portland Health Care System, Portland, OR, United States
| | - Ben Emery
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States
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16
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de Curtis M, Garbelli R, Uva L. A hypothesis for the role of axon demyelination in seizure generation. Epilepsia 2021; 62:583-595. [PMID: 33493363 DOI: 10.1111/epi.16824] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 01/04/2021] [Accepted: 01/05/2021] [Indexed: 01/06/2023]
Abstract
Loss of myelin and altered oligodendrocyte distribution in the cerebral cortex are commonly observed both in postsurgical tissue derived from different focal epilepsies (such as focal cortical dysplasias and tuberous sclerosis) and in animal models of focal epilepsy. Moreover, seizures are a frequent symptom in demyelinating diseases, such as multiple sclerosis, and in animal models of demyelination and oligodendrocyte dysfunction. Finally, the excessive activity reported in demyelinated axons may promote hyperexcitability. We hypothesize that the extracellular potassium rise generated during epileptiform activity may be amplified by the presence of axons without appropriate myelin coating and by alterations in oligodendrocyte function. This process could facilitate the triggering of recurrent spontaneous seizures in areas of altered myelination and could result in further demyelination, thus promoting epileptogenesis.
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Affiliation(s)
- Marco de Curtis
- Epilepsy Unit, IRCCS Foundation Carlo Besta Neurological Institute, Milan, Italy
| | - Rita Garbelli
- Epilepsy Unit, IRCCS Foundation Carlo Besta Neurological Institute, Milan, Italy
| | - Laura Uva
- Epilepsy Unit, IRCCS Foundation Carlo Besta Neurological Institute, Milan, Italy
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17
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Mozafari S, Deboux C, Laterza C, Ehrlich M, Kuhlmann T, Martino G, Baron-Van Evercooren A. Beneficial contribution of induced pluripotent stem cell-progeny to Connexin 47 dynamics during demyelination-remyelination. Glia 2020; 69:1094-1109. [PMID: 33301181 PMCID: PMC7984339 DOI: 10.1002/glia.23950] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 11/26/2020] [Accepted: 11/30/2020] [Indexed: 12/17/2022]
Abstract
Oligodendrocytes are extensively coupled to astrocytes, a phenomenon ensuring glial homeostasis and maintenance of central nervous system myelin. Molecular disruption of this communication occurs in demyelinating diseases such as multiple sclerosis. Less is known about the vulnerability and reconstruction of the panglial network during adult demyelination‐remyelination. Here, we took advantage of lysolcithin‐induced demyelination to investigate the expression dynamics of the oligodendrocyte specific connexin 47 (Cx47) and to some extent that of astrocyte Cx43, and whether this dynamic could be modulated by grafted induced pluripotent stem cell (iPSC)‐neural progeny. Our data show that disruption of Cx43‐Cx47 mediated hetero‐cellular gap‐junction intercellular communication following demyelination is larger in size than demyelination. Loss of Cx47 expression is timely rescued during remyelination and accelerated by the grafted neural precursors. Moreover, mouse and human iPSC‐derived oligodendrocytes express Cx47, which co‐labels with astrocyte Cx43, indicating their integration into the panglial network. These data suggest that in rodents, full lesion repair following transplantation occurs by panglial reconstruction in addition to remyelination. Targeting panglial elements by cell therapy or pharmacological compounds may help accelerating or stabilizing re/myelination in myelin disorders.
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Affiliation(s)
- Sabah Mozafari
- INSERM, U1127, Paris, France.,CNRS, UMR 7225, Paris, France.,Sorbonne Université UPMC Paris 06, UM-75, Paris, France.,ICM-GH Pitié-Salpêtrière, Paris, France
| | - Cyrille Deboux
- INSERM, U1127, Paris, France.,CNRS, UMR 7225, Paris, France.,Sorbonne Université UPMC Paris 06, UM-75, Paris, France.,ICM-GH Pitié-Salpêtrière, Paris, France
| | - Cecilia Laterza
- Institute of Experimental Neurology-DIBIT 2, Division of Neuroscience, IRCCS San Raffaele Hospital and Vita San Raffaele University, Milan, Italy.,Industrial Engineering Department, University of Padova, Padova, Italy
| | - Marc Ehrlich
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany.,Institute of Neuropathology, University Hospital Münster, Münster, Germany
| | - Tanja Kuhlmann
- Institute of Neuropathology, University Hospital Münster, Münster, Germany
| | - Gianvito Martino
- Institute of Experimental Neurology-DIBIT 2, Division of Neuroscience, IRCCS San Raffaele Hospital and Vita San Raffaele University, Milan, Italy
| | - Anne Baron-Van Evercooren
- INSERM, U1127, Paris, France.,CNRS, UMR 7225, Paris, France.,Sorbonne Université UPMC Paris 06, UM-75, Paris, France.,ICM-GH Pitié-Salpêtrière, Paris, France
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18
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Mozafari S, Starost L, Manot-Saillet B, Garcia-Diaz B, Xu YKT, Roussel D, Levy MJF, Ottoboni L, Kim KP, Schöler HR, Kennedy TE, Antel JP, Martino G, Angulo MC, Kuhlmann T, Baron-Van Evercooren A. Multiple sclerosis iPS-derived oligodendroglia conserve their properties to functionally interact with axons and glia in vivo. SCIENCE ADVANCES 2020; 6:6/49/eabc6983. [PMID: 33277253 PMCID: PMC7821889 DOI: 10.1126/sciadv.abc6983] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 10/22/2020] [Indexed: 05/04/2023]
Abstract
Remyelination failure in multiple sclerosis (MS) is associated with a migration/differentiation block of oligodendroglia. The reason for this block is highly debated. It could result from disease-related extrinsic or intrinsic regulators in oligodendroglial biology. To avoid confounding immune-mediated extrinsic effect, we used an immune-deficient mouse model to compare induced pluripotent stem cell-derived oligodendroglia from MS and healthy donors following engraftment in the developing CNS. We show that the MS-progeny behaves and differentiates into oligodendrocytes to the same extent as controls. They generate equal amounts of myelin, with bona fide nodes of Ranvier, and promote equal restoration of their host slow conduction. MS-progeny expressed oligodendrocyte- and astrocyte-specific connexins and established functional connections with donor and host glia. Thus, MS oligodendroglia, regardless of major immune manipulators, are intrinsically capable of myelination and making functional axo-glia/glia-glia connections, reinforcing the view that the MS oligodendrocyte differentiation block is not from major intrinsic oligodendroglial deficits.
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Affiliation(s)
- Sabah Mozafari
- INSERM, U1127, F-75013 Paris, France
- CNRS, UMR 7225, F-75013 Paris, France
- Sorbonne Université UPMC Paris 06, UM-75, F-75005, Paris, France
- ICM-GH Pitié-Salpêtrière, F-75013, Paris, France
| | - Laura Starost
- Institute of Neuropathology, University Hospital Münster, 48149 Münster, Germany
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, 48149 Münster, Germany
| | - Blandine Manot-Saillet
- Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM, Université de Paris, U1266, F-75014 Paris, France
- GHU PARIS Psychiatrie & Neurosciences, Paris, France
| | - Beatriz Garcia-Diaz
- INSERM, U1127, F-75013 Paris, France
- CNRS, UMR 7225, F-75013 Paris, France
- Sorbonne Université UPMC Paris 06, UM-75, F-75005, Paris, France
- ICM-GH Pitié-Salpêtrière, F-75013, Paris, France
| | - Yu Kang T Xu
- McGill Program in Neuroengineering, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Delphine Roussel
- INSERM, U1127, F-75013 Paris, France
- CNRS, UMR 7225, F-75013 Paris, France
- Sorbonne Université UPMC Paris 06, UM-75, F-75005, Paris, France
- ICM-GH Pitié-Salpêtrière, F-75013, Paris, France
| | - Marion J F Levy
- INSERM, U1127, F-75013 Paris, France
- CNRS, UMR 7225, F-75013 Paris, France
- Sorbonne Université UPMC Paris 06, UM-75, F-75005, Paris, France
- ICM-GH Pitié-Salpêtrière, F-75013, Paris, France
| | - Linda Ottoboni
- Institute of Experimental Neurology-DIBIT 2, Division of Neuroscience, IRCCS San Raffaele Hospital and Vita San Raffaele University, Milan, Italy
| | - Kee-Pyo Kim
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, 48149 Münster, Germany
| | - Hans R Schöler
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, 48149 Münster, Germany
| | - Timothy E Kennedy
- McGill Program in Neuroengineering, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Jack P Antel
- Neuroimmunology Unit, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Gianvito Martino
- Institute of Experimental Neurology-DIBIT 2, Division of Neuroscience, IRCCS San Raffaele Hospital and Vita San Raffaele University, Milan, Italy
| | - Maria Cecilia Angulo
- Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM, Université de Paris, U1266, F-75014 Paris, France
- GHU PARIS Psychiatrie & Neurosciences, Paris, France
| | - Tanja Kuhlmann
- Institute of Neuropathology, University Hospital Münster, 48149 Münster, Germany
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, 48149 Münster, Germany
| | - Anne Baron-Van Evercooren
- INSERM, U1127, F-75013 Paris, France.
- CNRS, UMR 7225, F-75013 Paris, France
- Sorbonne Université UPMC Paris 06, UM-75, F-75005, Paris, France
- ICM-GH Pitié-Salpêtrière, F-75013, Paris, France
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19
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Köhler S, Schmidt H, Fülle P, Hirrlinger J, Winkler U. A Dual Nanosensor Approach to Determine the Cytosolic Concentration of ATP in Astrocytes. Front Cell Neurosci 2020; 14:565921. [PMID: 33192312 PMCID: PMC7530325 DOI: 10.3389/fncel.2020.565921] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/26/2020] [Indexed: 11/17/2022] Open
Abstract
Adenosine triphosphate (ATP) is the central energy carrier of all cells and knowledge on the dynamics of the concentration of ATP ([ATP]) provides important insights into the energetic state of a cell. Several genetically encoded fluorescent nanosensors for ATP were developed, which allow following the cytosolic [ATP] at high spatial and temporal resolution using fluorescence microscopy. However, to calibrate the fluorescent signal to [ATP] has remained challenging. To estimate basal cytosolic [ATP] ([ATP]0) in astrocytes, we here took advantage of two ATP nanosensors of the ATeam-family (ATeam1.03; ATeam1.03YEMK) with different affinities for ATP. Altering [ATP] by external stimuli resulted in characteristic pairs of signal changes of both nanosensors, which depend on [ATP]0. Using this dual nanosensor strategy and epifluorescence microscopy, [ATP]0 was estimated to be around 1.5 mM in primary cultures of cortical astrocytes from mice. Furthermore, in astrocytes in acutely isolated cortical slices from mice expressing both nanosensors after stereotactic injection of AAV-vectors, 2-photon microscopy revealed [ATP]0 of 0.7 mM to 1.3 mM. Finally, the change in [ATP] induced in the cytosol of cultured cortical astrocytes by application of azide, glutamate, and an increased extracellular concentration of K+ were calculated as −0.50 mM, −0.16 mM, and 0.07 mM, respectively. In summary, the dual nanosensor approach adds another option for determining the concentration of [ATP] to the increasing toolbox of fluorescent nanosensors for metabolites. This approach can also be applied to other metabolites when two sensors with different binding properties are available.
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Affiliation(s)
- Susanne Köhler
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University Leipzig, Leipzig, Germany
| | - Hartmut Schmidt
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University Leipzig, Leipzig, Germany
| | - Paula Fülle
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University Leipzig, Leipzig, Germany.,Wilhelm-Ostwald-Schule, Gymnasium der Stadt Leipzig, Leipzig, Germany
| | - Johannes Hirrlinger
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University Leipzig, Leipzig, Germany.,Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
| | - Ulrike Winkler
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University Leipzig, Leipzig, Germany
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20
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Structural myelin defects are associated with low axonal ATP levels but rapid recovery from energy deprivation in a mouse model of spastic paraplegia. PLoS Biol 2020; 18:e3000943. [PMID: 33196637 PMCID: PMC7704050 DOI: 10.1371/journal.pbio.3000943] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 11/30/2020] [Accepted: 10/22/2020] [Indexed: 11/19/2022] Open
Abstract
In several neurodegenerative disorders, axonal pathology may originate from impaired oligodendrocyte-to-axon support of energy substrates. We previously established transgenic mice that allow measuring axonal ATP levels in electrically active optic nerves. Here, we utilize this technique to explore axonal ATP dynamics in the Plpnull/y mouse model of spastic paraplegia. Optic nerves from Plpnull/y mice exhibited lower and more variable basal axonal ATP levels and reduced compound action potential (CAP) amplitudes, providing a missing link between axonal pathology and a role of oligodendrocytes in brain energy metabolism. Surprisingly, when Plpnull/y optic nerves are challenged with transient glucose deprivation, both ATP levels and CAP decline slower, but recover faster upon reperfusion of glucose. Structurally, myelin sheaths display an increased frequency of cytosolic channels comprising glucose and monocarboxylate transporters, possibly facilitating accessibility of energy substrates to the axon. These data imply that complex metabolic alterations of the axon–myelin unit contribute to the phenotype of Plpnull/y mice. Imaging of ATP dynamics in the optic nerve axons of mice lacking the major myelin protein PLP (a model of spastic paraplegia) reveals complex alterations in the metabolic interaction between oligodendrocytes and axons, associated with structural deficits of myelin.
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21
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Mozafari S, Baron-Van Evercooren A. Human stem cell-derived oligodendrocytes: From humanized animal models to cell therapy in myelin diseases. Semin Cell Dev Biol 2020; 116:53-61. [PMID: 33082116 DOI: 10.1016/j.semcdb.2020.09.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/21/2020] [Accepted: 09/22/2020] [Indexed: 12/15/2022]
Abstract
Oligodendrocytes are main targets in demyelinating and dysmyelinating diseases of the central nervous system (CNS), but are also involved in accidental, neurodegenerative and psychiatric disorders. The underlying pathology of these diseases is not fully understood and treatments are still lacking. The recent discovery of the induced pluripotent stem cell (iPSC) technology has open the possibility to address the biology of human oligodendroglial cells both in the dish and in vivo via engraftment in animal models, and paves the way for the development of treatment for myelin disorders. In this review, we make a short overview of the different sources human oligodendroglial cells, and animal models available for pre-clinical cell therapy. We discuss the anatomical and functional benefit of grafted iPSC-progenitors over their brain counterparts, their use in disease modeling and the missing gaps that still prevent to study their biology in the most integrated way, and to translate iPSC-stem cell based therapy to the clinic.
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Affiliation(s)
- Sabah Mozafari
- Institut du Cerveau et de la Moelle Epinière-Groupe Hospitalier Pitié-Salpêtrière, INSERM, U1127, CNRS, UMR 7225, Sorbonne Université UM75, F-75013 Paris, France; CNRS, UMR 7225, Paris, France; Sorbonne Universités, Université Pierre et MarieCurie Paris 06, UM-75, Paris, France
| | - Anne Baron-Van Evercooren
- Institut du Cerveau et de la Moelle Epinière-Groupe Hospitalier Pitié-Salpêtrière, INSERM, U1127, CNRS, UMR 7225, Sorbonne Université UM75, F-75013 Paris, France; CNRS, UMR 7225, Paris, France; Sorbonne Universités, Université Pierre et MarieCurie Paris 06, UM-75, Paris, France.
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22
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Abou-Mrad Z, Alomari SO, Bsat S, Moussalem CK, Alok K, El Houshiemy MN, Alomari AO, Minassian GB, Omeis IA. Role of connexins in spinal cord injury: An update. Clin Neurol Neurosurg 2020; 197:106102. [DOI: 10.1016/j.clineuro.2020.106102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 07/16/2020] [Accepted: 07/18/2020] [Indexed: 01/25/2023]
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23
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Suissa L, Flachon V, Guigonis JM, Olivieri CV, Burel-Vandenbos F, Guglielmi J, Ambrosetti D, Gérard M, Franken P, Darcourt J, Pellerin L, Pourcher T, Lindenthal S. Urinary ketone body loss leads to degeneration of brain white matter in elderly SLC5A8-deficient mice. J Cereb Blood Flow Metab 2020; 40:1709-1723. [PMID: 31506013 PMCID: PMC7370371 DOI: 10.1177/0271678x19873662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
SLC5A8 is a sodium-coupled monocarboxylate and ketone transporter expressed in various epithelial cells. A putative role of SLC5A8 in neuroenergetics has been also hypothesized. To clarify this issue, we studied the cerebral phenotype of SLC5A8-deficient mice during aging. Elderly SLC5A8-deficient mice presented diffuse leukoencephalopathy characterized by intramyelinic oedema without demyelination suggesting chronic energetic crisis. Hypo-metabolism in the white matter of elderly SLC5A8-deficient mice was found using 99mTc-hexamethylpropyleneamine oxime (HMPAO) single-photon emission CT (SPECT). Since the SLC5A8 protein could not be detected in the mouse brain, it was hypothesized that the leukoencephalopathy of aging SLC5A8-deficient mice was caused by the absence of slc5a8 expression in a peripheral organ, i.e. the kidney, where SLC5A8 is strongly expressed. A hyper-excretion of the ketone β-hydroxybutyrate (BHB) in the urine of SLC5A8-deficient mice was observed and showed that SLC5A8-deficient mice suffered a cerebral BHB insufficiency. Elderly SLC5A8-deficient mice also presented altered glucose metabolism. We propose that the continuous renal loss of BHB leads to a chronic energetic deficiency in the brain of elderly SLC5A8-deficient mice who are unable to counterbalance their glucose deficit. This study highlights the importance of alternative energetic substrates in neuroenergetics especially under conditions of restricted glucose availability.
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Affiliation(s)
- Laurent Suissa
- Laboratory Transporter in Imaging and Radiotherapy in Oncology (TIRO), University Nice Sophia Antipolis, Institut de biosciences et biotechnologies d'Aix-Marseille (BIAM), Commissariat a l'Energie Atomique, University Côte d'Azur, Nice, France.,Intensive Care Stroke Unit, University Hospital, Nice, France
| | - Virginie Flachon
- Laboratory Transporter in Imaging and Radiotherapy in Oncology (TIRO), University Nice Sophia Antipolis, Institut de biosciences et biotechnologies d'Aix-Marseille (BIAM), Commissariat a l'Energie Atomique, University Côte d'Azur, Nice, France
| | - Jean-Marie Guigonis
- Laboratory Transporter in Imaging and Radiotherapy in Oncology (TIRO), University Nice Sophia Antipolis, Institut de biosciences et biotechnologies d'Aix-Marseille (BIAM), Commissariat a l'Energie Atomique, University Côte d'Azur, Nice, France
| | - Charles-Vivien Olivieri
- Laboratory Transporter in Imaging and Radiotherapy in Oncology (TIRO), University Nice Sophia Antipolis, Institut de biosciences et biotechnologies d'Aix-Marseille (BIAM), Commissariat a l'Energie Atomique, University Côte d'Azur, Nice, France
| | | | - Julien Guglielmi
- Laboratory Transporter in Imaging and Radiotherapy in Oncology (TIRO), University Nice Sophia Antipolis, Institut de biosciences et biotechnologies d'Aix-Marseille (BIAM), Commissariat a l'Energie Atomique, University Côte d'Azur, Nice, France
| | | | - Matthieu Gérard
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, University of Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Philippe Franken
- Laboratory Transporter in Imaging and Radiotherapy in Oncology (TIRO), University Nice Sophia Antipolis, Institut de biosciences et biotechnologies d'Aix-Marseille (BIAM), Commissariat a l'Energie Atomique, University Côte d'Azur, Nice, France.,Nuclear Medicine Department, Center Antoine Lacassagne, Nice, France
| | - Jacques Darcourt
- Laboratory Transporter in Imaging and Radiotherapy in Oncology (TIRO), University Nice Sophia Antipolis, Institut de biosciences et biotechnologies d'Aix-Marseille (BIAM), Commissariat a l'Energie Atomique, University Côte d'Azur, Nice, France.,Nuclear Medicine Department, Center Antoine Lacassagne, Nice, France
| | - Luc Pellerin
- Département de Physiologie, Université de Lausanne, Lausanne, Switzerland.,Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536 CNRS, Université de Bordeaux, Bordeaux, France
| | - Thierry Pourcher
- Laboratory Transporter in Imaging and Radiotherapy in Oncology (TIRO), University Nice Sophia Antipolis, Institut de biosciences et biotechnologies d'Aix-Marseille (BIAM), Commissariat a l'Energie Atomique, University Côte d'Azur, Nice, France
| | - Sabine Lindenthal
- Laboratory Transporter in Imaging and Radiotherapy in Oncology (TIRO), University Nice Sophia Antipolis, Institut de biosciences et biotechnologies d'Aix-Marseille (BIAM), Commissariat a l'Energie Atomique, University Côte d'Azur, Nice, France
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24
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Papaneophytou C, Georgiou E, Kleopa KA. The role of oligodendrocyte gap junctions in neuroinflammation. Channels (Austin) 2020; 13:247-263. [PMID: 31232168 PMCID: PMC6602578 DOI: 10.1080/19336950.2019.1631107] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Gap junctions (GJs) provide channels for direct cell-to-cell connectivity serving the homeostasis in several organs of vertebrates including the central (CNS) and peripheral (PNS) nervous systems. GJs are composed of connexins (Cx), which show a highly distinct cellular and subcellular expression pattern. Oligodendrocytes, the myelinating cells of the CNS, are characterized by extensive GJ connectivity with each other as well as with astrocytes. The main oligodendrocyte connexins forming these GJ channels are Cx47 and Cx32. The importance of these channels has been highlighted by the discovery of human diseases caused by mutations in oligodendrocyte connexins, manifesting with leukodystrophy or transient encephalopathy. Experimental models have provided further evidence that oligodendrocyte GJs are essential for CNS myelination and homeostasis, while a strong inflammatory component has been recognized in the absence of oligodendrocyte connexins. Further studies revealed that connexins are also disrupted in multiple sclerosis (MS) brain, and in experimental models of induced inflammatory demyelination. Moreover, induced demyelination was more severe and associated with higher degree of CNS inflammation in models with oligodendrocyte GJ deficiency, suggesting that disrupted connexin expression in oligodendrocytes is not only a consequence but can also drive a pro-inflammatory environment in acquired demyelinating disorders such as MS. In this review, we summarize the current insights from human disorders as well as from genetic and acquired models of demyelination related to oligodendrocyte connexins, with the remaining challenges and perspectives.
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Affiliation(s)
- Christos Papaneophytou
- a Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine , Nicosia , Cyprus.,b Department of Life and Health Sciences, School of Sciences and Engineering , University of Nicosia , Nicosia , Cyprus
| | - Elena Georgiou
- a Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine , Nicosia , Cyprus
| | - Kleopas A Kleopa
- a Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine , Nicosia , Cyprus.,c Neurology Clinics , the Cyprus Institute of Neurology and Genetics, and the Cyprus School of Molecular Medicine , Nicosia , Cyprus
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25
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Blackband SJ, Flint JJ, Hansen B, Shepherd TM, Lee CH, Streit WJ, Forder JR. On the Origins of Diffusion MRI Signal Changes in Stroke. Front Neurol 2020; 11:549. [PMID: 32714267 PMCID: PMC7344185 DOI: 10.3389/fneur.2020.00549] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 05/15/2020] [Indexed: 12/20/2022] Open
Abstract
Magnetic resonance imaging (MRI) is a leading diagnostic technique especially for neurological studies. However, the physical origin of the hyperintense signal seen in MR images of stroke immediately after ischemic onset in the brain has been a matter of debate since it was first demonstrated in 1990. In this article, we hypothesize and provide evidence that changes in the glial cells, comprising roughly one-half of the brain's cells and therefore a significant share of its volume, accompanying ischemia, are the root cause of the MRI signal change. Indeed, a primary function of the glial cells is osmoregulation in order to maintain homeostasis in the neurons and nerve fibers for accurate and consistent function. This realization also impacts our understanding of signal changes in other tissues following ischemia. We anticipate that this paradigm shift will facilitate new and improved models of MRI signals in tissues, which will, in turn, impact clinical utility.
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Affiliation(s)
- Stephen J Blackband
- Department of Neuroscience, University of Florida, Gainesville, FL, United States.,McKnight Brain Institute, University of Florida, Gainesville, FL, United States.,Center for Structural Biology, University of Florida, Gainesville, FL, United States.,National High Magnetic Field Laboratory, Tallahassee, FL, United States
| | - Jeremy J Flint
- Department of Neuroscience, University of Florida, Gainesville, FL, United States.,McKnight Brain Institute, University of Florida, Gainesville, FL, United States
| | - Brian Hansen
- Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | - Timothy M Shepherd
- Department of Radiology, New York University School of Medicine, New York, NY, United States
| | - Choong H Lee
- Department of Radiology, New York University School of Medicine, New York, NY, United States
| | - Wolfgang J Streit
- Department of Neuroscience, University of Florida, Gainesville, FL, United States
| | - John R Forder
- McKnight Brain Institute, University of Florida, Gainesville, FL, United States.,National High Magnetic Field Laboratory, Tallahassee, FL, United States.,Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States.,Department of Radiology, University of Florida, Gainesville, FL, United States
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26
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Wellman SM, Guzman K, Stieger KC, Brink LE, Sridhar S, Dubaniewicz MT, Li L, Cambi F, Kozai TDY. Cuprizone-induced oligodendrocyte loss and demyelination impairs recording performance of chronically implanted neural interfaces. Biomaterials 2020; 239:119842. [PMID: 32065972 PMCID: PMC7540937 DOI: 10.1016/j.biomaterials.2020.119842] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 01/29/2020] [Accepted: 02/03/2020] [Indexed: 12/16/2022]
Abstract
Biological inflammation induced during penetrating cortical injury can disrupt functional neuronal and glial activity within the cortex, resulting in potential recording failure of chronically implanted neural interfaces. Oligodendrocytes provide critical support for neuronal health and function through direct contact with neuronal soma and axons within the cortex. Given their fundamental role to regulate neuronal activity via myelin, coupled with their heightened vulnerability to metabolic brain injury due to high energetic demands, oligodendrocytes are hypothesized as a possible source of biological failure in declining recording performances of intracortical microelectrode devices. To determine the extent of their contribution to neuronal activity and function, a cuprizone-inducible model of oligodendrocyte depletion and demyelination in mice was performed prior to microelectrode implantation. At 5 weeks of cuprizone exposure, mice demonstrated significantly reduced cortical oligodendrocyte density and myelin expression. Mice were then implanted with functional recording microelectrodes in the visual cortex and neuronal activity was evaluated up to 7 weeks alongside continued cuprizone administration. Cuprizone-induced oligodendrocyte loss and demyelination was associated with significantly reduced recording performances at the onset of implantation, which remained relatively stable over time. In contast, recording performances for mice on a normal diet were intially elevated before decreasing over time to the recording level of tcuprizone-treated mice. Further electrophysiological analysis revealed deficits in multi-unit firing rates, frequency-dependent disruptions in neuronal oscillations, and altered laminar communication within the cortex of cuprizone-treated mice. Post-mortem immunohistochemistry revealed robust depletion of oligodendrocytes around implanted microelectrode arrays alongside comparable neuronal densities to control mice, suggesting that oligodendrocyte loss was a possible contributor to chronically impaired device performances. This study highlights potentially significant contributions from the oligodendrocyte lineage population concerning the biological integration and long-term functional performance of neural interfacing technology.
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Affiliation(s)
- Steven M Wellman
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; Center for Neural Basis of Cognition, Pittsburgh, PA, USA
| | - Kelly Guzman
- Veterans Administration Pittsburgh, Pittsburgh, PA, USA
| | - Kevin C Stieger
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; Center for Neural Basis of Cognition, Pittsburgh, PA, USA
| | | | - Sadhana Sridhar
- Veterans Administration Pittsburgh, Pittsburgh, PA, USA; Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Lehong Li
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Franca Cambi
- Veterans Administration Pittsburgh, Pittsburgh, PA, USA; Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Neurology, University of Kentucky, Lexington, KY, USA
| | - Takashi D Y Kozai
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; Center for Neural Basis of Cognition, Pittsburgh, PA, USA; Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA; McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA; NeuroTech Center, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA.
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27
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Giaume C, Naus CC, Sáez JC, Leybaert L. Glial Connexins and Pannexins in the Healthy and Diseased Brain. Physiol Rev 2020; 101:93-145. [PMID: 32326824 DOI: 10.1152/physrev.00043.2018] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Over the past several decades a large amount of data have established that glial cells, the main cell population in the brain, dynamically interact with neurons and thus impact their activity and survival. One typical feature of glia is their marked expression of several connexins, the membrane proteins forming intercellular gap junction channels and hemichannels. Pannexins, which have a tetraspan membrane topology as connexins, are also detected in glial cells. Here, we review the evidence that connexin and pannexin channels are actively involved in dynamic and metabolic neuroglial interactions in physiological as well as in pathological situations. These features of neuroglial interactions open the way to identify novel non-neuronal aspects that allow for a better understanding of behavior and information processing performed by neurons. This will also complement the "neurocentric" view by facilitating the development of glia-targeted therapeutic strategies in brain disease.
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Affiliation(s)
- Christian Giaume
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, Paris, France; University Pierre et Marie Curie, Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France; Department of Cellular & Physiological Sciences, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile; Instituo de Neurociencias, Centro Interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso, Chile; Physiology Group, Department of Basic and Applied Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Christian C Naus
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, Paris, France; University Pierre et Marie Curie, Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France; Department of Cellular & Physiological Sciences, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile; Instituo de Neurociencias, Centro Interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso, Chile; Physiology Group, Department of Basic and Applied Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Juan C Sáez
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, Paris, France; University Pierre et Marie Curie, Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France; Department of Cellular & Physiological Sciences, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile; Instituo de Neurociencias, Centro Interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso, Chile; Physiology Group, Department of Basic and Applied Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Luc Leybaert
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, Paris, France; University Pierre et Marie Curie, Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France; Department of Cellular & Physiological Sciences, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile; Instituo de Neurociencias, Centro Interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso, Chile; Physiology Group, Department of Basic and Applied Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
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28
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Heterogeneity of Astrocytes in Grey and White Matter. Neurochem Res 2019; 46:3-14. [PMID: 31797158 DOI: 10.1007/s11064-019-02926-x] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 11/21/2019] [Accepted: 11/28/2019] [Indexed: 02/07/2023]
Abstract
Astrocytes are a diverse and heterogeneous type of glial cells. The major task of grey and white matter areas in the brain are computation of information at neuronal synapses and propagation of action potentials along axons, respectively, resulting in diverse demands for astrocytes. Adapting their function to the requirements in the local environment, astrocytes differ in morphology, gene expression, metabolism, and many other properties. Here we review the differential properties of protoplasmic astrocytes of grey matter and fibrous astrocytes located in white matter in respect to glutamate and energy metabolism, to their function at the blood-brain interface and to coupling via gap junctions. Finally, we discuss how this astrocytic heterogeneity might contribute to the different susceptibility of grey and white matter to ischemic insults.
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29
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Suminaite D, Lyons DA, Livesey MR. Myelinated axon physiology and regulation of neural circuit function. Glia 2019; 67:2050-2062. [PMID: 31233642 PMCID: PMC6772175 DOI: 10.1002/glia.23665] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 05/28/2019] [Accepted: 06/06/2019] [Indexed: 12/15/2022]
Abstract
The study of structural and functional plasticity in the central nervous system (CNS) to date has focused primarily on that of neurons and synapses. However, more recent studies implicate glial cells as key regulators of neural circuit function. Among these, the myelinating glia of the CNS, oligodendrocytes, have been shown to be responsive to extrinsic signals including neuronal activity, and in turn, tune neurophysiological function. Due to the fact that myelin fundamentally alters the conduction properties of axons, much attention has focused on how dynamic regulation of myelination might represent a form of functional plasticity. Here, we highlight recent research that indicates that it is not only myelin, but essentially all the function-regulating components of the myelinated axon that are responsive to neuronal activity. For example, the axon initial segment, nodes of Ranvier, heminodes, axonal termini, and the morphology of the axon itself all exhibit the potential to respond to neuronal activity, and in so doing might underpin specific functional outputs. We also highlight emerging evidence that the myelin sheath itself has a rich physiology capable of influencing axonal physiology. We suggest that to fully understand nervous system plasticity we need to consider the fact that myelinated axon is an integrated functional unit and adaptations that influence the entire functional unit are likely to underpin modifications to neural circuit function.
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Affiliation(s)
| | - David A. Lyons
- Centre for Discovery Brain SciencesUniversity of EdinburghEdinburghUK
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30
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Abstract
Leukodystrophies are genetically determined disorders affecting the white matter of the central nervous system. The combination of MRI pattern recognition and next-generation sequencing for the definition of novel disease entities has recently demonstrated that many leukodystrophies are due to the primary involvement and/or mutations in genes selectively expressed by cell types other than the oligodendrocytes, the myelin-forming cells in the brain. This has led to a new definition of leukodystrophies as genetic white matter disorders resulting from the involvement of any white matter structural component. As a result, the research has shifted its main focus from oligodendrocytes to other types of neuroglia. Astrocytes are the housekeeping cells of the nervous system, responsible for maintaining homeostasis and normal brain physiology and to orchestrate repair upon injury. Several lines of evidence show that astrocytic interactions with the other white matter cellular constituents play a primary pathophysiologic role in many leukodystrophies. These are thus now classified as astrocytopathies. This chapter addresses how the crosstalk between astrocytes, other glial cells, axons and non-neural cells are essential for the integrity and maintenance of the white matter in health. It also addresses the current knowledge of the cellular pathomechanisms of astrocytic leukodystrophies, and specifically Alexander disease, vanishing white matter, megalencephalic leukoencephalopathy with subcortical cysts and Aicardi-Goutière Syndrome.
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Affiliation(s)
- M S Jorge
- Department of Pathology, Free University Medical Centre, Amsterdam, The Netherlands
| | - Marianna Bugiani
- Department of Pathology, Free University Medical Centre, Amsterdam, The Netherlands.
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31
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Stadelmann C, Timmler S, Barrantes-Freer A, Simons M. Myelin in the Central Nervous System: Structure, Function, and Pathology. Physiol Rev 2019; 99:1381-1431. [PMID: 31066630 DOI: 10.1152/physrev.00031.2018] [Citation(s) in RCA: 357] [Impact Index Per Article: 59.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Oligodendrocytes generate multiple layers of myelin membrane around axons of the central nervous system to enable fast and efficient nerve conduction. Until recently, saltatory nerve conduction was considered the only purpose of myelin, but it is now clear that myelin has more functions. In fact, myelinating oligodendrocytes are embedded in a vast network of interconnected glial and neuronal cells, and increasing evidence supports an active role of oligodendrocytes within this assembly, for example, by providing metabolic support to neurons, by regulating ion and water homeostasis, and by adapting to activity-dependent neuronal signals. The molecular complexity governing these interactions requires an in-depth molecular understanding of how oligodendrocytes and axons interact and how they generate, maintain, and remodel their myelin sheaths. This review deals with the biology of myelin, the expanded relationship of myelin with its underlying axons and the neighboring cells, and its disturbances in various diseases such as multiple sclerosis, acute disseminated encephalomyelitis, and neuromyelitis optica spectrum disorders. Furthermore, we will highlight how specific interactions between astrocytes, oligodendrocytes, and microglia contribute to demyelination in hereditary white matter pathologies.
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Affiliation(s)
- Christine Stadelmann
- Institute of Neuropathology, University Medical Center Göttingen , Göttingen , Germany ; Institute of Neuronal Cell Biology, Technical University Munich , Munich , Germany ; German Center for Neurodegenerative Diseases (DZNE), Munich , Germany ; Department of Neuropathology, University Medical Center Leipzig , Leipzig , Germany ; Munich Cluster of Systems Neurology (SyNergy), Munich , Germany ; and Max Planck Institute of Experimental Medicine, Göttingen , Germany
| | - Sebastian Timmler
- Institute of Neuropathology, University Medical Center Göttingen , Göttingen , Germany ; Institute of Neuronal Cell Biology, Technical University Munich , Munich , Germany ; German Center for Neurodegenerative Diseases (DZNE), Munich , Germany ; Department of Neuropathology, University Medical Center Leipzig , Leipzig , Germany ; Munich Cluster of Systems Neurology (SyNergy), Munich , Germany ; and Max Planck Institute of Experimental Medicine, Göttingen , Germany
| | - Alonso Barrantes-Freer
- Institute of Neuropathology, University Medical Center Göttingen , Göttingen , Germany ; Institute of Neuronal Cell Biology, Technical University Munich , Munich , Germany ; German Center for Neurodegenerative Diseases (DZNE), Munich , Germany ; Department of Neuropathology, University Medical Center Leipzig , Leipzig , Germany ; Munich Cluster of Systems Neurology (SyNergy), Munich , Germany ; and Max Planck Institute of Experimental Medicine, Göttingen , Germany
| | - Mikael Simons
- Institute of Neuropathology, University Medical Center Göttingen , Göttingen , Germany ; Institute of Neuronal Cell Biology, Technical University Munich , Munich , Germany ; German Center for Neurodegenerative Diseases (DZNE), Munich , Germany ; Department of Neuropathology, University Medical Center Leipzig , Leipzig , Germany ; Munich Cluster of Systems Neurology (SyNergy), Munich , Germany ; and Max Planck Institute of Experimental Medicine, Göttingen , Germany
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32
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Cisterna BA, Arroyo P, Puebla C. Role of Connexin-Based Gap Junction Channels in Communication of Myelin Sheath in Schwann Cells. Front Cell Neurosci 2019; 13:69. [PMID: 30881289 PMCID: PMC6405416 DOI: 10.3389/fncel.2019.00069] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Accepted: 02/12/2019] [Indexed: 12/21/2022] Open
Abstract
Peripheral nerves have the capacity to conduct action potentials along great distances and quickly recover following damage which is mainly due to Schwann cells (SCs), the most abundant glial cells of the peripheral nervous system (PNS). SCs wrap around an axonal segment multiple times, forming a myelin sheath, allowing for a significant increase in action potential conduction by insulating the axons. Mature myelin consists of compact and non-compact (or cytoplasmic) myelin zones. Non-compact myelin is found in paranodal loops bordering the nodes of Ranvier, and in the inner and outermost cytoplasmic tongues and is the region in which Schmidt-Lanterman incisures (SLI; continuous spirals of overlapping cytoplasmic expansions within areas of compact myelin) are located. Using different technologies, it was shown that the layers of non-compact myelin could be connected to each other by gap junction channels (GJCs), formed by connexin 32 (Cx32), and their relative abundance allows for the transfer of ions and different small molecules. Likewise, Cx29 is expressed in the innermost layer of the myelin sheath. Here it does not form GJCs but colocalizes with Kv1, which implies that the SCs play an active role in the electrical condition in mammals. The critical role of GJCs in the functioning of myelinating SCs is evident in Charcot-Marie-Tooth disease (CMT), X-linked form 1 (CMTX1), which is caused by mutations in the gap junction protein beta 1 (GJB1) gene that codes for Cx32. Although the management of CMT symptoms is currently supportive, there is a recent method for targeted gene delivery to myelinating cells, which rescues the phenotype in KO-Cx32 mice, a model of CMTX1. In this mini-review article, we discuss the current knowledge on the role of Cxs in myelin-forming SCs and summarize recent discoveries that may become a real treatment possibility for patients with disorders such as CMT.
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Affiliation(s)
- Bruno A Cisterna
- Escuela de Medicina, Universidad de Talca, Talca, Chile.,Centro para el Desarrollo de la Nanociencia y Nanotecnología (CEDENNA), Universidad de Santiago de Chile, Santiago, Chile
| | - Pablo Arroyo
- Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carlos Puebla
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
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33
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Elorza-Vidal X, Gaitán-Peñas H, Estévez R. Chloride Channels in Astrocytes: Structure, Roles in Brain Homeostasis and Implications in Disease. Int J Mol Sci 2019; 20:ijms20051034. [PMID: 30818802 PMCID: PMC6429410 DOI: 10.3390/ijms20051034] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 02/15/2019] [Accepted: 02/17/2019] [Indexed: 12/29/2022] Open
Abstract
Astrocytes are the most abundant cell type in the CNS (central nervous system). They exert multiple functions during development and in the adult CNS that are essential for brain homeostasis. Both cation and anion channel activities have been identified in astrocytes and it is believed that they play key roles in astrocyte function. Whereas the proteins and the physiological roles assigned to cation channels are becoming very clear, the study of astrocytic chloride channels is in its early stages. In recent years, we have moved from the identification of chloride channel activities present in astrocyte primary culture to the identification of the proteins involved in these activities, the determination of their 3D structure and attempts to gain insights about their physiological role. Here, we review the recent findings related to the main chloride channels identified in astrocytes: the voltage-dependent ClC-2, the calcium-activated bestrophin, the volume-activated VRAC (volume-regulated anion channel) and the stress-activated Maxi-Cl−. We discuss key aspects of channel biophysics and structure with a focus on their role in glial physiology and human disease.
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Affiliation(s)
- Xabier Elorza-Vidal
- Unitat de Fisiologia, Departament de Ciències Fisiològiques, Genes Disease and Therapy Program IDIBELL-Institute of Neurosciences, Universitat de Barcelona, L'Hospitalet de Llobregat, 08907 Barcelona, Spain.
- Centro de Investigación en red de enfermedades raras (CIBERER), ISCIII, 08907 Barcelona, Spain.
| | - Héctor Gaitán-Peñas
- Unitat de Fisiologia, Departament de Ciències Fisiològiques, Genes Disease and Therapy Program IDIBELL-Institute of Neurosciences, Universitat de Barcelona, L'Hospitalet de Llobregat, 08907 Barcelona, Spain.
- Centro de Investigación en red de enfermedades raras (CIBERER), ISCIII, 08907 Barcelona, Spain.
| | - Raúl Estévez
- Unitat de Fisiologia, Departament de Ciències Fisiològiques, Genes Disease and Therapy Program IDIBELL-Institute of Neurosciences, Universitat de Barcelona, L'Hospitalet de Llobregat, 08907 Barcelona, Spain.
- Centro de Investigación en red de enfermedades raras (CIBERER), ISCIII, 08907 Barcelona, Spain.
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Vejar S, Oyarzún JE, Retamal MA, Ortiz FC, Orellana JA. Connexin and Pannexin-Based Channels in Oligodendrocytes: Implications in Brain Health and Disease. Front Cell Neurosci 2019; 13:3. [PMID: 30760982 PMCID: PMC6361860 DOI: 10.3389/fncel.2019.00003] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 01/07/2019] [Indexed: 11/13/2022] Open
Abstract
Oligodendrocytes are the myelin forming cells in the central nervous system (CNS). In addition to this main physiological function, these cells play key roles by providing energy substrates to neurons as well as information required to sustain proper synaptic transmission and plasticity at the CNS. The latter requires a fine coordinated intercellular communication with neurons and other glial cell types, including astrocytes. In mammals, tissue synchronization is mainly mediated by connexins and pannexins, two protein families that underpin the communication among neighboring cells through the formation of different plasma membrane channels. At one end, gap junction channels (GJCs; which are exclusively formed by connexins in vertebrates) connect the cytoplasm of contacting cells allowing electrical and metabolic coupling. At the other end, hemichannels and pannexons (which are formed by connexins and pannexins, respectively) communicate the intra- and extracellular compartments, serving as diffusion pathways of ions and small molecules. Here, we briefly review the current knowledge about the expression and function of hemichannels, pannexons and GJCs in oligodendrocytes, as well as the evidence regarding the possible role of these channels in metabolic and synaptic functions at the CNS. In particular, we focus on oligodendrocyte-astrocyte coupling during axon metabolic support and its implications in brain health and disease.
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Affiliation(s)
- Sebastián Vejar
- Mechanisms of Myelin Formation and Repair Laboratory, Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - Juan E. Oyarzún
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
- Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Mauricio A. Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
- Department of Cell Physiology and Molecular Biophysics, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Fernando C. Ortiz
- Mechanisms of Myelin Formation and Repair Laboratory, Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - Juan A. Orellana
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
- Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Pontificia Universidad Católica de Chile, Santiago, Chile
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35
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Min R, van der Knaap MS. Genetic defects disrupting glial ion and water homeostasis in the brain. Brain Pathol 2019; 28:372-387. [PMID: 29740942 PMCID: PMC8028498 DOI: 10.1111/bpa.12602] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 03/02/2018] [Indexed: 12/23/2022] Open
Abstract
Electrical activity of neurons in the brain, caused by the movement of ions between intracellular and extracellular compartments, is the basis of all our thoughts and actions. Maintaining the correct ionic concentration gradients is therefore crucial for brain functioning. Ion fluxes are accompanied by the displacement of osmotically obliged water. Since even minor brain swelling leads to severe brain damage and even death, brain ion and water movement has to be tightly regulated. Glial cells, in particular astrocytes, play a key role in ion and water homeostasis. They are endowed with specific channels, pumps and carriers to regulate ion and water flow. Glial cells form a large panglial syncytium to aid the uptake and dispersal of ions and water, and make extensive contacts with brain fluid barriers for disposal of excess ions and water. Genetic defects in glial proteins involved in ion and water homeostasis disrupt brain functioning, thereby leading to neurological diseases. Since white matter edema is often a hallmark disease feature, many of these diseases are characterized as leukodystrophies. In this review we summarize our current understanding of inherited glial diseases characterized by disturbed brain ion and water homeostasis by integrating findings from MRI, genetics, neuropathology and animal models for disease. We discuss how mutations in different glial proteins lead to disease, and highlight the similarities and differences between these diseases. To come to effective therapies for this group of diseases, a better mechanistic understanding of how glial cells shape ion and water movement in the brain is crucial.
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Affiliation(s)
- Rogier Min
- Department of Child Neurology, Amsterdam Neuroscience, VU University Medical Center, Amsterdam, The Netherlands.,Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
| | - Marjo S van der Knaap
- Department of Child Neurology, Amsterdam Neuroscience, VU University Medical Center, Amsterdam, The Netherlands.,Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
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36
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Bursting at the Seams: Molecular Mechanisms Mediating Astrocyte Swelling. Int J Mol Sci 2019; 20:ijms20020330. [PMID: 30650535 PMCID: PMC6359623 DOI: 10.3390/ijms20020330] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 01/10/2019] [Accepted: 01/11/2019] [Indexed: 01/31/2023] Open
Abstract
Brain swelling is one of the most robust predictors of outcome following brain injury, including ischemic, traumatic, hemorrhagic, metabolic or other injury. Depending on the specific type of insult, brain swelling can arise from the combined space-occupying effects of extravasated blood, extracellular edema fluid, cellular swelling, vascular engorgement and hydrocephalus. Of these, arguably the least well appreciated is cellular swelling. Here, we explore current knowledge regarding swelling of astrocytes, the most abundant cell type in the brain, and the one most likely to contribute to pathological brain swelling. We review the major molecular mechanisms identified to date that contribute to or mitigate astrocyte swelling via ion transport, and we touch upon the implications of astrocyte swelling in health and disease.
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37
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Spees WM, Lin TH, Sun P, Song C, George A, Gary SE, Yang HC, Song SK. MRI-based assessment of function and dysfunction in myelinated axons. Proc Natl Acad Sci U S A 2018; 115:E10225-E10234. [PMID: 30297414 PMCID: PMC6205472 DOI: 10.1073/pnas.1801788115] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Repetitive electrical activity produces microstructural alteration in myelinated axons, which may afford the opportunity to noninvasively monitor function of myelinated fibers in peripheral nervous system (PNS)/CNS pathways. Microstructural changes were assessed via two different magnetic-resonance-based approaches: diffusion fMRI and dynamic T2 spectroscopy in the ex vivo perfused bullfrog sciatic nerves. Using this robust, classical model as a platform for testing, we demonstrate that noninvasive diffusion fMRI, based on standard diffusion tensor imaging (DTI), can clearly localize the sites of axonal conduction blockage as might be encountered in neurotrauma or other lesion types. It is also shown that the diffusion fMRI response is graded in proportion to the total number of electrical impulses carried through a given locus. Dynamic T2 spectroscopy of the perfused frog nerves point to an electrical-activity-induced redistribution of tissue water and myelin structural changes. Diffusion basis spectrum imaging (DBSI) reveals a reversible shift of tissue water into a restricted isotropic diffusion signal component. Submyelinic vacuoles are observed in electron-microscopy images of tissue fixed during electrical stimulation. A slowing of the compound action potential conduction velocity accompanies repetitive electrical activity. Correlations between electrophysiology and MRI parameters during and immediately after stimulation are presented. Potential mechanisms and interpretations of these results are discussed.
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Affiliation(s)
- William M Spees
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110;
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110
| | - Tsen-Hsuan Lin
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Peng Sun
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Chunyu Song
- Department of Biomedical Engineering, Washington University, St. Louis, MO 63110
| | - Ajit George
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Sam E Gary
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Hsin-Chieh Yang
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Sheng-Kwei Song
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110
- Department of Biomedical Engineering, Washington University, St. Louis, MO 63110
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38
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Köhler S, Winkler U, Sicker M, Hirrlinger J. NBCe1 mediates the regulation of the NADH/NAD + redox state in cortical astrocytes by neuronal signals. Glia 2018; 66:2233-2245. [PMID: 30208253 DOI: 10.1002/glia.23504] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 06/19/2018] [Accepted: 06/25/2018] [Indexed: 12/20/2022]
Abstract
Astrocytes are a glial cell type, which is indispensable for brain energy metabolism. Within cells, the NADH/NAD+ redox state is a crucial node in metabolism connecting catabolic pathways to oxidative phosphorylation and ATP production in mitochondria. To characterize the dynamics of the intracellular NADH/NAD+ redox state in cortical astrocytes Peredox, a genetically encoded sensor for the NADH/NAD+ redox state, was expressed in cultured cortical astrocytes as well as in cortical astrocytes in acutely isolated brain slices. Calibration of the sensor in cultured astrocytes revealed a mean basal cytosolic NADH/NAD+ redox ratio of about 0.01; however, with a broad distribution and heterogeneity in the cell population, which was mirrored by a heterogeneous basal cellular concentration of lactate. Inhibition of glucose uptake decreased the NADH/NAD+ redox state while inhibition of lactate dehydrogenase or of lactate release resulted in an increase in the NADH/NAD+ redox ratio. Furthermore, the NADH/NAD+ redox state was regulated by the extracellular concentration of K+ , and application of the neurotransmitters ATP or glutamate increased the NADH/NAD+ redox state dependent on purinergic receptors and glutamate uptake, respectively. This regulation by K+ , ATP, and glutamate involved NBCe1 mediated sodium-bicarbonate transport. These results demonstrate that the NADH/NAD+ redox state in astrocytes is a metabolic node regulated by neuronal signals reflecting physiological activity, most likely contributing to adjust astrocytic metabolism to energy demand of the brain.
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Affiliation(s)
- Susanne Köhler
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Ulrike Winkler
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Marit Sicker
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Johannes Hirrlinger
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany.,Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
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39
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Schirmer L, Möbius W, Zhao C, Cruz-Herranz A, Ben Haim L, Cordano C, Shiow LR, Kelley KW, Sadowski B, Timmons G, Pröbstel AK, Wright JN, Sin JH, Devereux M, Morrison DE, Chang SM, Sabeur K, Green AJ, Nave KA, Franklin RJ, Rowitch DH. Oligodendrocyte-encoded Kir4.1 function is required for axonal integrity. eLife 2018; 7:36428. [PMID: 30204081 PMCID: PMC6167053 DOI: 10.7554/elife.36428] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 09/09/2018] [Indexed: 12/17/2022] Open
Abstract
Glial support is critical for normal axon function and can become dysregulated in white matter (WM) disease. In humans, loss-of-function mutations of KCNJ10, which encodes the inward-rectifying potassium channel KIR4.1, causes seizures and progressive neurological decline. We investigated Kir4.1 functions in oligodendrocytes (OLs) during development, adulthood and after WM injury. We observed that Kir4.1 channels localized to perinodal areas and the inner myelin tongue, suggesting roles in juxta-axonal K+ removal. Conditional knockout (cKO) of OL-Kcnj10 resulted in late onset mitochondrial damage and axonal degeneration. This was accompanied by neuronal loss and neuro-axonal dysfunction in adult OL-Kcnj10 cKO mice as shown by delayed visual evoked potentials, inner retinal thinning and progressive motor deficits. Axon pathologies in OL-Kcnj10 cKO were exacerbated after WM injury in the spinal cord. Our findings point towards a critical role of OL-Kir4.1 for long-term maintenance of axonal function and integrity during adulthood and after WM injury.
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Affiliation(s)
- Lucas Schirmer
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California, United States.,Department of Pediatrics, University of California, San Francisco, San Francisco, United States.,Department of Paediatrics, University of Cambridge, Cambridge, United Kingdom.,Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, United Kingdom
| | - Wiebke Möbius
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Chao Zhao
- Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, United Kingdom.,Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Andrés Cruz-Herranz
- Department of Neurology, University of California, San Francisco, San Francisco, United States.,Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, United States
| | - Lucile Ben Haim
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California, United States.,Department of Pediatrics, University of California, San Francisco, San Francisco, United States
| | - Christian Cordano
- Department of Neurology, University of California, San Francisco, San Francisco, United States.,Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, United States
| | - Lawrence R Shiow
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California, United States.,Department of Pediatrics, University of California, San Francisco, San Francisco, United States
| | - Kevin W Kelley
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California, United States.,Department of Pediatrics, University of California, San Francisco, San Francisco, United States
| | - Boguslawa Sadowski
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Garrett Timmons
- Department of Neurology, University of California, San Francisco, San Francisco, United States.,Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, United States
| | - Anne-Katrin Pröbstel
- Department of Neurology, University of California, San Francisco, San Francisco, United States.,Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, United States
| | - Jackie N Wright
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California, United States.,Department of Pediatrics, University of California, San Francisco, San Francisco, United States
| | - Jung Hyung Sin
- Department of Neurology, University of California, San Francisco, San Francisco, United States.,Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, United States
| | - Michael Devereux
- Department of Neurology, University of California, San Francisco, San Francisco, United States.,Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, United States
| | - Daniel E Morrison
- Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, United Kingdom.,Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Sandra M Chang
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California, United States.,Department of Pediatrics, University of California, San Francisco, San Francisco, United States
| | - Khalida Sabeur
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California, United States.,Department of Pediatrics, University of California, San Francisco, San Francisco, United States
| | - Ari J Green
- Department of Neurology, University of California, San Francisco, San Francisco, United States.,Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, United States.,Department of Ophthalmology, University of California, San Francisco, San Francisco, United States
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Robin Jm Franklin
- Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, United Kingdom.,Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - David H Rowitch
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California, United States.,Department of Pediatrics, University of California, San Francisco, San Francisco, United States.,Department of Paediatrics, University of Cambridge, Cambridge, United Kingdom.,Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, United Kingdom.,Department of Neurosurgery, University of California, San Francisco, San Francisco, United States
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40
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Fasciani I, Pluta P, González-Nieto D, Martínez-Montero P, Molano J, Paíno CL, Millet O, Barrio LC. Directional coupling of oligodendrocyte connexin-47 and astrocyte connexin-43 gap junctions. Glia 2018; 66:2340-2352. [PMID: 30144323 DOI: 10.1002/glia.23471] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 05/21/2018] [Accepted: 05/22/2018] [Indexed: 12/15/2022]
Abstract
Intercellular communication via gap junction channels between oligodendrocytes and between astrocytes as well as between these cell types is essential to maintain the integrity of myelin in the central nervous system. Oligodendrocyte gap junction connexin-47 (Cx47) is a key element in this crosstalk and indeed, mutations in human Cx47 cause severe myelin disorders. However, the permeation properties of channels of Cx47 alone and in heterotypic combination with astrocyte Cx43 remain unclear. We show here that Cx47 contains three extra residues at 5' amino-terminus that play a critical role in the channel pore structure and account for relative low ionic conductivity, cationic permselectivity and voltage-gating properties of oligodendrocyte-oligodendrocyte Cx47 channels. Regarding oligodendrocyte-astrocyte coupling, heterotypic channels formed by Cx47 with Cx43 exhibit ionic and chemical rectification, which creates a directional diffusion barrier for the movement of ions and larger negatively charged molecules from cells expressing Cx47 to those with Cx43. The restrictive permeability of Cx47 channels and the diffusion barrier of Cx47-Cx43 channels was abolished by a mutation associated with leukodystrophy, the Cx47P90S, suggesting a novel pathogenic mechanism underlying myelin disorders that involves alterations in the panglial permeation.
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Affiliation(s)
- Ilaria Fasciani
- Unit of Experimental Neurology and Neurobiology, "Ramón y Cajal" Hospital-IRYCIS, Carretera de Colmenar km 9, Madrid, 28034, Spain
| | - Paula Pluta
- Structural Biology Unit of CIC bioGUNE, Bizkaia Technology Park, Building 800, Derio, 48160, Spain
| | - Daniel González-Nieto
- Biomedical Research Networking Center in Bioengineering Biomaterials and Nanomedicine (CIBER-BBN), 28040 Madrid, and Center for Biomedical Technology, Universidad Politécnica de Madrid, Campus de Montegancedo S/N, Pozuelo de Alarcón, Madrid, 28223, Spain
| | - Paloma Martínez-Montero
- Unit of Molecular Genetics-INGEMM, Hospital "La Paz"-IDIPAZ, Paseo de la Castellana 261, 28046-Madrid, Spain
| | - Jesús Molano
- Unit of Molecular Genetics-INGEMM, Hospital "La Paz"-IDIPAZ, Paseo de la Castellana 261, 28046-Madrid, Spain
| | - Carlos L Paíno
- Unit of Experimental Neurology and Neurobiology, "Ramón y Cajal" Hospital-IRYCIS, Carretera de Colmenar km 9, Madrid, 28034, Spain
| | - Oscar Millet
- Structural Biology Unit of CIC bioGUNE, Bizkaia Technology Park, Building 800, Derio, 48160, Spain
| | - Luis C Barrio
- Unit of Experimental Neurology and Neurobiology, "Ramón y Cajal" Hospital-IRYCIS, Carretera de Colmenar km 9, Madrid, 28034, Spain
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41
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Potassium dynamics and seizures: Why is potassium ictogenic? Epilepsy Res 2018; 143:50-59. [DOI: 10.1016/j.eplepsyres.2018.04.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/26/2018] [Accepted: 04/07/2018] [Indexed: 01/01/2023]
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42
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Unusual white matter involvement in EAST syndrome associated with novel KCNJ10 mutations. J Neurol 2018; 265:1419-1425. [PMID: 29666984 DOI: 10.1007/s00415-018-8826-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 03/05/2018] [Accepted: 03/08/2018] [Indexed: 01/06/2023]
Abstract
BACKGROUND Epilepsy, ataxia, sensorineural deafness, and tubulopathy (EAST syndrome) is a rare channelopathy due to KCNJ10 mutations. So far, only mild cerebellar hypoplasia and/or dentate nuclei abnormalities have been reported as major neuroimaging findings in these patients. METHODS We analyzed the clinical and brain MRI features of two unrelated patients (aged 27 and 23 years) with EAST syndrome carrying novel homozygous frameshift mutations (p.Asn232Glnfs*14and p.Gly275Valfs*7) in KCNJ10, detected by whole exome sequencing. RESULTS Brain MRI examinations at 8 years in Patient 1 and at 13 years in Patient 2 revealed a peculiar brain and spinal cord involvement characterized by restricted diffusion of globi pallidi, thalami, brainstem, dentate nuclei, and cervical spinal cord in keeping with intramyelinic edema. The follow-up studies, performed, respectively, after 19 and 10 years, showed mild cerebellar atrophy and slight progression of the brain and spinal cord T2 signal abnormalities with increase of the restricted diffusion in the affected regions. CONCLUSION The present cases harboring novel homozygous frameshift mutations in KCNJ10 expand the spectrum of brain abnormalities in EAST syndrome, including mild cerebellar atrophy and intramyelinic edema, resulting from abnormal function of the Kir4.1 inwardly rectifying potassium channel at the astrocyte endfeet, with disruption of water-ion homeostasis.
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43
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Larson VA, Mironova Y, Vanderpool KG, Waisman A, Rash JE, Agarwal A, Bergles DE. Oligodendrocytes control potassium accumulation in white matter and seizure susceptibility. eLife 2018; 7:34829. [PMID: 29596047 PMCID: PMC5903864 DOI: 10.7554/elife.34829] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 03/28/2018] [Indexed: 12/19/2022] Open
Abstract
The inwardly rectifying K+ channel Kir4.1 is broadly expressed by CNS glia and deficits in Kir4.1 lead to seizures and myelin vacuolization. However, the role of oligodendrocyte Kir4.1 channels in controlling myelination and K+ clearance in white matter has not been defined. Here, we show that selective deletion of Kir4.1 from oligodendrocyte progenitors (OPCs) or mature oligodendrocytes did not impair their development or disrupt the structure of myelin. However, mice lacking oligodendrocyte Kir4.1 channels exhibited profound functional impairments, including slower clearance of extracellular K+ and delayed recovery of axons from repetitive stimulation in white matter, as well as spontaneous seizures, a lower seizure threshold, and activity-dependent motor deficits. These results indicate that Kir4.1 channels in oligodendrocytes play an important role in extracellular K+ homeostasis in white matter, and that selective loss of this channel from oligodendrocytes is sufficient to impair K+ clearance and promote seizures.
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Affiliation(s)
- Valerie A Larson
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Yevgeniya Mironova
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Kimberly G Vanderpool
- Department of Biomedical Sciences, Colorado State University, Fort Collins, United States
| | - Ari Waisman
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - John E Rash
- Department of Biomedical Sciences, Colorado State University, Fort Collins, United States
| | - Amit Agarwal
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Dwight E Bergles
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States
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44
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Zhou Y, Zhang H, Zhang L, Cao X, Yang R, Feng Q, Yap PT, Shen D. Functional MRI registration with tissue-specific patch-based functional correlation tensors. Hum Brain Mapp 2018; 39:2303-2316. [PMID: 29504193 DOI: 10.1002/hbm.24021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Accepted: 02/17/2018] [Indexed: 02/01/2023] Open
Abstract
Population studies of brain function with resting-state functional magnetic resonance imaging (rs-fMRI) rely on accurate intersubject registration of functional areas. This is typically achieved through registration using high-resolution structural images with more spatial details and better tissue contrast. However, accumulating evidence has suggested that such strategy cannot align functional regions well because functional areas are not necessarily consistent with anatomical structures. To alleviate this problem, a number of registration algorithms based directly on rs-fMRI data have been developed, most of which utilize functional connectivity (FC) features for registration. However, most of these methods usually extract functional features only from the thin and highly curved cortical grey matter (GM), posing great challenges to accurate estimation of whole-brain deformation fields. In this article, we demonstrate that additional useful functional features can also be extracted from the whole brain, not restricted to the GM, particularly the white-matter (WM), for improving the overall functional registration. Specifically, we quantify local anisotropic correlation patterns of the blood oxygenation level-dependent (BOLD) signals using tissue-specific patch-based functional correlation tensors (ts-PFCTs) in both GM and WM. Functional registration is then performed by integrating the features from different tissues using the multi-channel large deformation diffeomorphic metric mapping (mLDDMM) algorithm. Experimental results show that our method achieves superior functional registration performance, compared with conventional registration methods.
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Affiliation(s)
- Yujia Zhou
- Guangdong Provincial Key Laboratory of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China.,Department of Radiology and BRIC, University of North Carolina, Chapel Hill, North Carolina
| | - Han Zhang
- Department of Radiology and BRIC, University of North Carolina, Chapel Hill, North Carolina
| | - Lichi Zhang
- School of Biomedical Engineering, Shanghai Jiao Tong University, China.,Department of Radiology and BRIC, University of North Carolina, Chapel Hill, North Carolina
| | - Xiaohuan Cao
- Department of Radiology and BRIC, University of North Carolina, Chapel Hill, North Carolina.,School of Automation, Northwestern Polytechnical University, Xi'an, China
| | - Ru Yang
- Guangdong Provincial Key Laboratory of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China.,Department of Radiology and BRIC, University of North Carolina, Chapel Hill, North Carolina
| | - Qianjin Feng
- Guangdong Provincial Key Laboratory of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China
| | - Pew-Thian Yap
- Department of Radiology and BRIC, University of North Carolina, Chapel Hill, North Carolina
| | - Dinggang Shen
- Department of Radiology and BRIC, University of North Carolina, Chapel Hill, North Carolina.,Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Republic of Korea
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Let's Be Superficial About Ictal Activity. Epilepsy Curr 2017; 17:299-300. [PMID: 29225545 DOI: 10.5698/1535-7597.17.5.299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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van der Knaap MS, Bugiani M. Leukodystrophies: a proposed classification system based on pathological changes and pathogenetic mechanisms. Acta Neuropathol 2017; 134:351-382. [PMID: 28638987 PMCID: PMC5563342 DOI: 10.1007/s00401-017-1739-1] [Citation(s) in RCA: 241] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 06/06/2017] [Accepted: 06/06/2017] [Indexed: 12/29/2022]
Abstract
Leukodystrophies are genetically determined disorders characterized by the selective involvement of the central nervous system white matter. Onset may be at any age, from prenatal life to senescence. Many leukodystrophies are degenerative in nature, but some only impair white matter function. The clinical course is mostly progressive, but may also be static or even improving with time. Progressive leukodystrophies are often fatal, and no curative treatment is known. The last decade has witnessed a tremendous increase in the number of defined leukodystrophies also owing to a diagnostic approach combining magnetic resonance imaging pattern recognition and next generation sequencing. Knowledge on white matter physiology and pathology has also dramatically built up. This led to the recognition that only few leukodystrophies are due to mutations in myelin- or oligodendrocyte-specific genes, and many are rather caused by defects in other white matter structural components, including astrocytes, microglia, axons and blood vessels. We here propose a novel classification of leukodystrophies that takes into account the primary involvement of any white matter component. Categories in this classification are the myelin disorders due to a primary defect in oligodendrocytes or myelin (hypomyelinating and demyelinating leukodystrophies, leukodystrophies with myelin vacuolization); astrocytopathies; leuko-axonopathies; microgliopathies; and leuko-vasculopathies. Following this classification, we illustrate the neuropathology and disease mechanisms of some leukodystrophies taken as example for each category. Some leukodystrophies fall into more than one category. Given the complex molecular and cellular interplay underlying white matter pathology, recognition of the cellular pathology behind a disease becomes crucial in addressing possible treatment strategies.
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Affiliation(s)
- Marjo S van der Knaap
- Department of Pediatrics/Child Neurology, VU University Medical Centre, Amsterdam Neuroscience, Amsterdam, The Netherlands
- Department of Functional Genomics, Centre for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
| | - Marianna Bugiani
- Department of Pediatrics/Child Neurology, VU University Medical Centre, Amsterdam Neuroscience, Amsterdam, The Netherlands.
- Department of Pathology, VU University Medical Centre, Amsterdam Neuroscience, Amsterdam, The Netherlands.
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Sirisi S, Elorza-Vidal X, Arnedo T, Armand-Ugón M, Callejo G, Capdevila-Nortes X, López-Hernández T, Schulte U, Barrallo-Gimeno A, Nunes V, Gasull X, Estévez R. Depolarization causes the formation of a ternary complex between GlialCAM, MLC1 and ClC-2 in astrocytes: implications in megalencephalic leukoencephalopathy. Hum Mol Genet 2017; 26:2436-2450. [DOI: 10.1093/hmg/ddx134] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 03/29/2017] [Indexed: 01/06/2023] Open
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Pathogenesis of white matter changes in cerebral small vessel diseases: beyond vessel-intrinsic mechanisms. Clin Sci (Lond) 2017; 131:635-651. [DOI: 10.1042/cs20160380] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Revised: 01/04/2017] [Accepted: 01/16/2017] [Indexed: 01/08/2023]
Abstract
Cerebral small vessel diseases (SVDs) are a leading cause of age and hypertension-related stroke and dementia. The salient features of SVDs visible on conventional brain magnetic resonance images include white matter hyperintensities (WMHs) on T2-weighted images, small infarcts, macrohemorrhages, dilated perivascular spaces, microbleeds and brain atrophy. Among these, WMHs are the most common and often the earliest brain tissue changes. Moreover, over the past two decades, large population- and patient-based studies have established the clinical importance of WMHs, notably with respect to cognitive and motor disturbances. Here, we seek to provide a new and critical look at the pathogenesis of SVD-associated white matter (WM) changes. We first review our current knowledge of WM biology in the healthy brain, and then consider the main clinical and pathological features of WM changes in SVDs. The most widely held view is that SVD-associated WM lesions are caused by chronic hypoperfusion, impaired cerebrovascular reactivity (CVR) or blood–brain barrier (BBB) leakage. Here, we assess the arguments for and against each of these mechanisms based on population, patient and experimental model studies, and further discuss other potential mechanisms. Specifically, building on two recent seminal studies that have uncovered an anatomical and functional relationship between oligodendrocyte progenitor cells and blood vessels, we elaborate on how small vessel changes might compromise myelin remodelling and cause WM degeneration. Finally, we propose new directions for future studies on this hot research topic.
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A Novel Focal Seizure Pattern Generated in Superficial Layers of the Olfactory Cortex. J Neurosci 2017; 37:3544-3554. [PMID: 28264979 DOI: 10.1523/jneurosci.2239-16.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 12/06/2016] [Accepted: 12/16/2016] [Indexed: 02/03/2023] Open
Abstract
Seizure patterns identified in focal epilepsies caused by diverse etiologies are likely due to different pathogenic mechanisms. We describe here a novel, region-specific focal seizure pattern that mimics seizure activity observed in a subpopulation of patients submitted to presurgical monitoring with intracerebral electrodes. Distinctive seizure-like events (SLEs) are induced in the olfactory regions by acute treatment of both tangential brain slices and the isolated guinea pig brain with the potassium channel blocker 4-aminopyridine. Analysis of field potentials, intracellular activities, and extracellular potassium changes demonstrates that SLEs in the piriform cortex initiate in the superficial layer 1 lacking principal neurons with an activity-dependent increase of extracellular potassium. SLE progression (but not onset) does not require the participation of synaptic transmission and is mediated by diffusion of potassium to deep cortical layers. The novel seizure pattern here described is not observed in other cortical regions; it is proposed to rely on the peculiar organization of the superficial piriform cortex layers, which are characterized by unmyelinated axons and perisynaptic astroglial envelopes. This study reveals a sequence of ictogenic events in the olfactory cortex that were never described before in other cortical structures and supports the notion that altered potassium homeostasis and unmyelinated fibers may represent a potential vehicle for focal ictogenesis.SIGNIFICANCE STATEMENT We describe a novel seizure pattern peculiar of the olfactory cortex that resembles focal seizures with low-voltage fast activity at onset observed in humans. The findings suggest that network mechanisms responsible for seizure onset can be region specific.
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p53-Mediated oligodendrocyte apoptosis initiates demyelination after compressed spinal cord injury by enhancing ER-mitochondria interaction and E2F1 expression. Neurosci Lett 2017; 644:55-61. [DOI: 10.1016/j.neulet.2017.02.038] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 02/12/2017] [Accepted: 02/14/2017] [Indexed: 11/21/2022]
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