1
|
Fischer M, Kukley M. Hidden in the white matter: Current views on interstitial white matter neurons. Neuroscientist 2024:10738584241282969. [PMID: 39365761 DOI: 10.1177/10738584241282969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2024]
Abstract
The mammalian brain comprises two structurally and functionally distinct compartments: the gray matter (GM) and the white matter (WM). In humans, the WM constitutes approximately half of the brain volume, yet it remains significantly less investigated than the GM. The major cellular elements of the WM are neuronal axons and glial cells. However, the WM also contains cell bodies of the interstitial neurons, estimated to number 10 to 28 million in the adult bat brain, 67 million in Lar gibbon brain, and 450 to 670 million in the adult human brain, representing as much as 1.3%, 2.25%, and 3.5% of all neurons in the cerebral cortex, respectively. Many studies investigated the interstitial WM neurons (IWMNs) using immunohistochemistry, and some information is available regarding their electrophysiological properties. However, the functional role of IWMNs in physiologic and pathologic conditions largely remains unknown. This review aims to provide a concise update regarding the distribution and properties of interstitial WM neurons, highlight possible functions of these cells as debated in the literature, and speculate about other possible functions of the IWMNs and their interactions with glial cells. We hope that our review will inspire new research on IWMNs, which represent an intriguing cell population in the brain.
Collapse
Affiliation(s)
- Maximilian Fischer
- Institut de Neurociències and Departamento Bioquímica i Biología Molecular, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Maria Kukley
- Achucarro Basque Centre for Neuroscience, Leioa, Spain
- IKERBASQUE Basque Foundation for Science, Bilbao, Spain
| |
Collapse
|
2
|
Juvenal G, Higa GSV, Bonfim Marques L, Tessari Zampieri T, Costa Viana FJ, Britto LR, Tang Y, Illes P, di Virgilio F, Ulrich H, de Pasquale R. Regulation of GABAergic neurotransmission by purinergic receptors in brain physiology and disease. Purinergic Signal 2024:10.1007/s11302-024-10034-x. [PMID: 39046648 DOI: 10.1007/s11302-024-10034-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 06/19/2024] [Indexed: 07/25/2024] Open
Abstract
Purinergic receptors regulate the processing of neural information in the hippocampus and cerebral cortex, structures related to cognitive functions. These receptors are activated when astrocytic and neuronal populations release adenosine triphosphate (ATP) in an autocrine and paracrine manner, following sustained patterns of neuronal activity. The modulation by these receptors of GABAergic transmission has only recently been studied. Through their ramifications, astrocytes and GABAergic interneurons reach large groups of excitatory pyramidal neurons. Their inhibitory effect establishes different synchronization patterns that determine gamma frequency rhythms, which characterize neural activities related to cognitive processes. During early life, GABAergic-mediated synchronization of excitatory signals directs the experience-driven maturation of cognitive development, and dysfunctions concerning this process have been associated with neurological and neuropsychiatric diseases. Purinergic receptors timely modulate GABAergic control over ongoing neural activity and deeply affect neural processing in the hippocampal and neocortical circuitry. Stimulation of A2 receptors increases GABA release from presynaptic terminals, leading to a considerable reduction in neuronal firing of pyramidal neurons. A1 receptors inhibit GABAergic activity but only act in the early postnatal period when GABA produces excitatory signals. P2X and P2Y receptors expressed in pyramidal neurons reduce the inhibitory tone by blocking GABAA receptors. Finally, P2Y receptor activation elicits depolarization of GABAergic neurons and increases GABA release, thus favoring the emergence of gamma oscillations. The present review provides an overall picture of purinergic influence on GABAergic transmission and its consequences on neural processing, extending the discussion to receptor subtypes and their involvement in the onset of brain disorders, including epilepsy and Alzheimer's disease.
Collapse
Affiliation(s)
- Guilherme Juvenal
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, Brazil
| | - Guilherme Shigueto Vilar Higa
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, Brazil
- Department of Biophysics and Physiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Lucas Bonfim Marques
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, Brazil
| | - Thais Tessari Zampieri
- Department of Biophysics and Physiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Felipe José Costa Viana
- Department of Biophysics and Physiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Luiz R Britto
- Department of Biophysics and Physiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Yong Tang
- International Joint Research Centre On Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
- School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
| | - Peter Illes
- International Joint Research Centre On Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
- School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
- Rudolf Boehm Institute for Pharmacology and Toxicology, University of Leipzig, 04107, Leipzig, Germany
| | | | - Henning Ulrich
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, Brazil.
- International Joint Research Centre On Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China.
| | - Roberto de Pasquale
- Department of Biophysics and Physiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
| |
Collapse
|
3
|
Mortensen JS, Mikkelsen ANL, Wellendorph P. Ways of modulating GABA transporters to treat neurological disease. Expert Opin Ther Targets 2024; 28:529-543. [PMID: 39068514 DOI: 10.1080/14728222.2024.2383611] [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: 03/21/2024] [Accepted: 07/19/2024] [Indexed: 07/30/2024]
Abstract
INTRODUCTION The main inhibitory neurotransmitter in the central nervous system (CNS), γ-aminobutyric acid (GABA), is involved in a multitude of neurological and psychiatric disorders characterized by an imbalance in excitatory and inhibitory signaling. Regulation of extracellular levels of GABA is maintained by the four GABA transporters (GATs; GAT1, GAT2, GAT3, and BGT1), Na+/Cl--coupled transporters of the solute carrier 6 (SLC6) family. Despite mounting evidence for the involvement of the non-GAT1 GABA transporters in diseases, only GAT1 has successfully been translated into clinical practice via the drug tiagabine. AREAS COVERED In this review, all four GATs will be described in terms of their involvement in disease, and the most recent data on structure, function, expression, and localization discussed in relation to their potential role as drug targets. This includes an overview of various ways to modulate the GATs in relation to treatment of diseases caused by imbalances in the GABAergic system. EXPERT OPINION The recent publication of various GAT1 structures is an important milestone for future development of compounds targeting the GATs. Such information can provide much needed insight into mechanistic aspects of all GAT subtypes and be utilized to design improved ligands for this highly interesting drug target class.
Collapse
Affiliation(s)
- Jonas S Mortensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Amalie N L Mikkelsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Petrine Wellendorph
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
4
|
Shen W, Nwosu G, Honer M, Clasadonte J, Schmalzbauer S, Biven M, Langer K, Flamm C, Poliquin S, Mermer F, Dedeurwaerdere S, Hernandez MC, Kang JQ. γ-Aminobutyric acid transporter and GABA A receptor mechanisms in Slc6a1+/A288V and Slc6a1+/S295L mice associated with developmental and epileptic encephalopathies. Brain Commun 2024; 6:fcae110. [PMID: 38650830 PMCID: PMC11032196 DOI: 10.1093/braincomms/fcae110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 01/09/2024] [Accepted: 04/11/2024] [Indexed: 04/25/2024] Open
Abstract
We have previously characterized the molecular mechanisms for variants in γ-aminobutyric acid transporter 1-encoding solute carrier family 6-member 1 (SLC6A1) in vitro and concluded that a partial or complete loss of γ-aminobutyric acid uptake due to impaired protein trafficking is the primary aetiology. Impairment of γ-aminobutyric acid transporter 1 function could cause compensatory changes in the expression of γ-aminobutyric acid receptors, which, in turn, modify disease pathophysiology and phenotype. Here we used different approaches including radioactive 3H γ-aminobutyric acid uptake in cells and synaptosomes, immunohistochemistry and confocal microscopy as well as brain slice surface protein biotinylation to characterize Slc6a1+/A288V and Slc6a1+/S295L mice, representative of a partial or a complete loss of function of SLC6A1 mutations, respectively. We employed the γ-aminobutyric acid transporter 1-specific inhibitor [3H]tiagabine binding and GABAA receptor subunit-specific radioligand binding to profile the γ-aminobutyric acid transporter 1 and GABAA receptor expression in major brain regions such as cortex, cerebellum, hippocampus and thalamus. We also determined the total and surface expression of γ-aminobutyric acid transporter 1, γ-aminobutyric acid transporter 3 and expression of GABAA receptor in the major brain regions in the knockin mice. We found that γ-aminobutyric acid transporter 1 protein was markedly reduced in cortex, hippocampus, thalamus and cerebellum in both mutant mouse lines. Consistent with the findings of reduced γ-aminobutyric acid uptake for both γ-aminobutyric acid transporter 1(A288V) and γ-aminobutyric acid transporter 1(S295L), both the total and the γ-aminobutyric acid transporter 1-mediated 3H γ-aminobutyric acid reuptake was reduced. We found that γ-aminobutyric acid transporter 3 is only abundantly expressed in the thalamus and there was no compensatory increase of γ-aminobutyric acid transporter 3 in either of the mutant mouse lines. γ-Aminobutyric acid transporter 1 was reduced in both somatic regions and nonsomatic regions in both mouse models, in which a ring-like structure was identified only in the Slc6a1+/A288V mouse, suggesting more γ-aminobutyric acid transporter 1 retention inside endoplasmic reticulum in the Slc6a1+/A288V mouse. The [3H]tiagabine binding was similar in both mouse models despite the difference in γ-aminobutyric acid uptake function and γ-aminobutyric acid transporter 1 protein expression for both mutations. There were no differences in GABAA receptor subtype expression, except for a small increase in the expression of α5 subunits of GABAA receptor in the hippocampus of Slc6a1S295L homozygous mice, suggesting a potential interaction between the expression of this GABAA receptor subtype and the mutant γ-aminobutyric acid transporter 1. The study provides the first comprehensive characterization of the SLC6A1 mutations in vivo in two representative mouse models. Because both γ-aminobutyric acid transporter 1 and GABAA receptors are targets for anti-seizure medications, the findings from this study can help guide tailored treatment options based on the expression and function of γ-aminobutyric acid transporter 1 and GABAA receptor in SLC6A1 mutation-mediated neurodevelopmental and epileptic encephalopathies.
Collapse
Affiliation(s)
- Wangzhen Shen
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Gerald Nwosu
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Neuroscience Graduate Program, Vanderbilt University, Nashville, TN 37232, USA
- Vanderbilt Brain Institute, Nashville, TN 37240, USA
- Department of Biochemistry, Cancer Biology, Neuroscience and Pharmacology, Meharry Medical College, Nashville, TN 37232, USA
| | - Michael Honer
- Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Basel 4070, Switzerland
| | - Jerome Clasadonte
- Early Solutions, Neuroscience TA, UCB Biopharma SRL, Braine l’Alleud 1420, Belgium
| | - Svenja Schmalzbauer
- Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Basel 4070, Switzerland
| | - Marshall Biven
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Katherine Langer
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Carson Flamm
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Sarah Poliquin
- Neuroscience Graduate Program, Vanderbilt University, Nashville, TN 37232, USA
- Vanderbilt Brain Institute, Nashville, TN 37240, USA
| | - Felicia Mermer
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | | | - Maria-Clemencia Hernandez
- Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Basel 4070, Switzerland
| | - Jing-Qiong Kang
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Brain Institute, Nashville, TN 37240, USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
- Vanderbilt Kennedy Center of Human Development, Nashville, TN 37232, USA
| |
Collapse
|
5
|
Di Palma M, Catalano M, Serpe C, De Luca M, Monaco L, Kunzelmann K, Limatola C, Conti F, Fattorini G. Lipopolysaccharide augments microglial GABA uptake by increasing GABA transporter-1 trafficking and bestrophin-1 expression. Glia 2023; 71:2527-2540. [PMID: 37431178 DOI: 10.1002/glia.24437] [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: 02/14/2023] [Revised: 06/16/2023] [Accepted: 06/22/2023] [Indexed: 07/12/2023]
Abstract
Gamma-aminobutyric acid (GABA), the principal inhibitory neurotransmitter in the brain, affects numerous immune cell functions. Microglia, the brain's resident innate immune cells, regulate GABA signaling through GABA receptors and express the complete GABAergic machinery for GABA synthesis, uptake, and release. Here, the use of primary microglial cell cultures and ex vivo brain tissue sections allowed for demonstrating that treatment with lipopolysaccharide (LPS) increased microglial GABA uptake as well as GABA transporter (GAT)-1 trafficking. This effect was not entirely abolished by treatment with GAT inhibitors (GAT-Is). Notably, LPS also induced microglial upregulation of bestrophin-1 (BEST-1), a Ca2+ -activated Cl- channel permeable to GABA. Combined administration of GAT-Is and a BEST-1 inhibitor completely abolished LPS-induced microglial GABA uptake. Interestingly, increased microglial GAT-1 membrane turnover via syntaxin 1A was detected in LPS-treated cultures after BEST-1 blockade. Altogether, these findings provided evidence for a novel mechanism through which LPS may trigger the inflammatory response by directly altering microglial GABA clearance and identified the GAT-1/BEST-1 interplay as a potential novel mechanism involved in brain inflammation.
Collapse
Affiliation(s)
- Michael Di Palma
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
| | - Myriam Catalano
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Carmela Serpe
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Mariassunta De Luca
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Lucia Monaco
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Regensburg, Germany
| | - Cristina Limatola
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
- IRCCS Neuromed, Pozzilli, Italy
| | - Fiorenzo Conti
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
- Center for Neurobiology of Aging, INRCA IRCCS, Ancona, Italy
- Fondazione di Medicina Molecolare, Università Politecnica delle Marche, Ancona, Italy
| | - Giorgia Fattorini
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
- Center for Neurobiology of Aging, INRCA IRCCS, Ancona, Italy
| |
Collapse
|
6
|
Koh W, Kwak H, Cheong E, Lee CJ. GABA tone regulation and its cognitive functions in the brain. Nat Rev Neurosci 2023; 24:523-539. [PMID: 37495761 DOI: 10.1038/s41583-023-00724-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2023] [Indexed: 07/28/2023]
Abstract
γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter released at GABAergic synapses, mediating fast-acting phasic inhibition. Emerging lines of evidence unequivocally indicate that a small amount of extracellular GABA - GABA tone - exists in the brain and induces a tonic GABA current that controls neuronal activity on a slow timescale relative to that of phasic inhibition. Surprisingly, studies indicate that glial cells that synthesize GABA, such as astrocytes, release GABA through non-vesicular mechanisms, such as channel-mediated release, and thereby act as the source of GABA tone in the brain. In this Review, we first provide an overview of major advances in our understanding of the cell-specific molecular and cellular mechanisms of GABA synthesis, release and clearance that regulate GABA tone in various brain regions. We next examine the diverse ways in which the tonic GABA current regulates synaptic transmission and synaptic plasticity through extrasynaptic GABAA-receptor-mediated mechanisms. Last, we discuss the physiological mechanisms through which tonic inhibition modulates cognitive function on a slow timescale. In this Review, we emphasize that the cognitive functions of tonic GABA current extend beyond mere inhibition, laying a foundation for future research on the physiological and pathophysiological roles of GABA tone regulation in normal and abnormal psychiatric conditions.
Collapse
Affiliation(s)
- Wuhyun Koh
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, South Korea
| | - Hankyul Kwak
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Eunji Cheong
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea.
| | - C Justin Lee
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, South Korea.
| |
Collapse
|
7
|
Wang X, Rao X, Zhang J, Gan J. Genetic mechanisms in generalized epilepsies. ACTA EPILEPTOLOGICA 2023. [DOI: 10.1186/s42494-023-00118-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023] Open
Abstract
AbstractThe genetic generalized epilepsies (GGEs) have been proved to generate from genetic impact by twin studies and family studies. The genetic mechanisms of generalized epilepsies are always updating over time. Although the genetics of GGE is complex, there are always new susceptibility genes coming up as well as copy number variations which can lead to important breakthroughs in exploring the problem. At the same time, the development of ClinGen fades out some of the candidate genes. This means we have to figure out what accounts for a reliable gene for GGE, in another word, which gene has sufficient evidence for GGE. This will improve our understanding of the genetic mechanisms of GGE. In this review, important up-to-date genetic mechanisms of GGE were discussed.
Collapse
|
8
|
Astrocytes regulate inhibitory neurotransmission through GABA uptake, metabolism, and recycling. Essays Biochem 2023; 67:77-91. [PMID: 36806927 DOI: 10.1042/ebc20220208] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 01/03/2023] [Accepted: 01/05/2023] [Indexed: 02/23/2023]
Abstract
Synaptic regulation of the primary inhibitory neurotransmitter γ-aminobutyric acid (GABA) is essential for brain function. Cerebral GABA homeostasis is tightly regulated through multiple mechanisms and is directly coupled to the metabolic collaboration between neurons and astrocytes. In this essay, we outline and discuss the fundamental roles of astrocytes in regulating synaptic GABA signaling. A major fraction of synaptic GABA is removed from the synapse by astrocytic uptake. Astrocytes utilize GABA as a metabolic substrate to support glutamine synthesis. The astrocyte-derived glutamine is subsequently transferred to neurons where it serves as the primary precursor of neuronal GABA synthesis. The flow of GABA and glutamine between neurons and astrocytes is collectively termed the GABA-glutamine cycle and is essential to sustain GABA synthesis and inhibitory signaling. In certain brain areas, astrocytes are even capable of synthesizing and releasing GABA to modulate inhibitory transmission. The majority of oxidative GABA metabolism in the brain takes place in astrocytes, which also leads to synthesis of the GABA-related metabolite γ-hydroxybutyric acid (GHB). The physiological roles of endogenous GHB remain unclear, but may be related to regulation of tonic inhibition and synaptic plasticity. Disrupted inhibitory signaling and dysfunctional astrocyte GABA handling are implicated in several diseases including epilepsy and Alzheimer's disease. Synaptic GABA homeostasis is under astrocytic control and astrocyte GABA uptake, metabolism, and recycling may therefore serve as relevant targets to ameliorate pathological inhibitory signaling.
Collapse
|
9
|
Zhang X, Liu Y, Hong X, Li X, Meshul CK, Moore C, Yang Y, Han Y, Li WG, Qi X, Lou H, Duan S, Xu TL, Tong X. NG2 glia-derived GABA release tunes inhibitory synapses and contributes to stress-induced anxiety. Nat Commun 2021; 12:5740. [PMID: 34593806 PMCID: PMC8484468 DOI: 10.1038/s41467-021-25956-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/09/2021] [Indexed: 11/08/2022] Open
Abstract
NG2 glia, also known as oligodendrocyte precursor cells (OPCs), play an important role in proliferation and give rise to myelinating oligodendrocytes during early brain development. In contrast to other glial cell types, the most intriguing aspect of NG2 glia is their ability to directly sense synaptic inputs from neurons. However, whether this synaptic interaction is bidirectional or unidirectional, or its physiological relevance has not yet been clarified. Here, we report that NG2 glia form synaptic complexes with hippocampal interneurons and that selective photostimulation of NG2 glia (expressing channelrhodopsin-2) functionally drives GABA release and enhances inhibitory synaptic transmission onto proximal interneurons in a microcircuit. The mechanism involves GAD67 biosynthesis and VAMP-2 containing vesicular exocytosis. Further, behavioral assays demonstrate that NG2 glia photoactivation triggers anxiety-like behavior in vivo and contributes to chronic social defeat stress.
Collapse
Affiliation(s)
- Xiao Zhang
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yao Liu
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaoqi Hong
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xia Li
- Institute of Special Environmental Medicine, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Charles K Meshul
- Research Services, VA Medical Center, Portland, OR, USA
- Department of Behavioral Neuroscience and Pathology, Oregon Health & Science University, Portland, OR, USA
| | - Cynthia Moore
- Research Services, VA Medical Center, Portland, OR, USA
| | - Yabing Yang
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yanfei Han
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wei-Guang Li
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xin Qi
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Huifang Lou
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Shumin Duan
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Tian-Le Xu
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaoping Tong
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai, China.
| |
Collapse
|
10
|
Panthi S, Lyons NMA, Leitch B. Impact of Dysfunctional Feed-Forward Inhibition on Glutamate Decarboxylase Isoforms and γ-Aminobutyric Acid Transporters. Int J Mol Sci 2021; 22:ijms22147740. [PMID: 34299369 PMCID: PMC8306481 DOI: 10.3390/ijms22147740] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 07/16/2021] [Indexed: 12/02/2022] Open
Abstract
Absence seizures are associated with generalised synchronous 2.5–4 Hz spike-wave discharges causing brief and sudden alteration of awareness during childhood, which is known as childhood absence epilepsy (CAE). CAE is also associated with impaired learning, psychosocial challenges, and physical danger. Absence seizures arise from disturbances within the cortico-thalamocortical (CTC) network, including dysfunctional feed-forward inhibition (FFI); however, the precise mechanisms remain unclear. In epileptic stargazers, a genetic mouse model of CAE with chronic seizures, levels of γ-aminobutyric acid (GABA), and expression of GABA receptors are altered within the CTC network, implicating altered GABAergic transmission in absence seizures. However, the expression of GABA synthesising enzymes (GAD65 and GAD67) and GABA transporters (GAT-1 and 3) have not yet been characterised within absence seizure models. We found a specific upregulation of GAD65 in the somatosensory cortex but not the thalamus of epileptic stargazer mice. No differences were detected in GAD67 and GAT-3 levels in the thalamus or somatosensory cortex. Then, we assessed if GAD65 upregulation also occurred in Gi-DREADD mice exhibiting acute absence seizures, but we found no change in the expression profiles of GAD65/67 or GAT-3. Thus, the upregulation of GAD65 in stargazers may be a compensatory mechanism in response to long-term dysfunctional FFI and chronic absence seizures.
Collapse
Affiliation(s)
| | | | - Beulah Leitch
- Correspondence: ; Tel.: +64-3-479-7618; Fax: +64-3-479-7254
| |
Collapse
|
11
|
Bai X, Kirchhoff F, Scheller A. Oligodendroglial GABAergic Signaling: More Than Inhibition! Neurosci Bull 2021; 37:1039-1050. [PMID: 33928492 PMCID: PMC8275815 DOI: 10.1007/s12264-021-00693-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 11/22/2020] [Indexed: 12/12/2022] Open
Abstract
GABA is the main inhibitory neurotransmitter in the CNS acting at two distinct types of receptor: ligand-gated ionotropic GABAA receptors and G protein-coupled metabotropic GABAB receptors, thus mediating fast and slow inhibition of excitability at central synapses. GABAergic signal transmission has been intensively studied in neurons in contrast to oligodendrocytes and their precursors (OPCs), although the latter express both types of GABA receptor. Recent studies focusing on interneuron myelination and interneuron-OPC synapses have shed light on the importance of GABA signaling in the oligodendrocyte lineage. In this review, we start with a short summary on GABA itself and neuronal GABAergic signaling. Then, we elaborate on the physiological role of GABA receptors within the oligodendrocyte lineage and conclude with a description of these receptors as putative targets in treatments of CNS diseases.
Collapse
Affiliation(s)
- Xianshu Bai
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, 66421, Homburg, Germany
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, 66421, Homburg, Germany.
| | - Anja Scheller
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, 66421, Homburg, Germany
| |
Collapse
|
12
|
Goodspeed K, Pérez-Palma E, Iqbal S, Cooper D, Scimemi A, Johannesen KM, Stefanski A, Demarest S, Helbig KL, Kang J, Shaffo FC, Prentice B, Brownstein CA, Lim B, Helbig I, De Los Reyes E, McKnight D, Crunelli V, Campbell AJ, Møller RS, Freed A, Lal D. Current knowledge of SLC6A1-related neurodevelopmental disorders. Brain Commun 2020; 2:fcaa170. [PMID: 33241211 PMCID: PMC7677605 DOI: 10.1093/braincomms/fcaa170] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 09/09/2020] [Accepted: 09/14/2020] [Indexed: 12/18/2022] Open
Abstract
Advances in gene discovery have identified genetic variants in the solute carrier family 6 member 1 gene as a monogenic cause of neurodevelopmental disorders, including epilepsy with myoclonic atonic seizures, autism spectrum disorder and intellectual disability. The solute carrier family 6 member 1 gene encodes for the GABA transporter protein type 1, which is responsible for the reuptake of the neurotransmitter GABA, the primary inhibitory neurotransmitter in the central nervous system, from the extracellular space. GABAergic inhibition is essential to counterbalance neuronal excitation, and when significantly disrupted, it negatively impacts brain development leading to developmental differences and seizures. Aggregation of patient variants and observed clinical manifestations expand understanding of the genotypic and phenotypic spectrum of this disorder. Here, we assess genetic and phenotypic features in 116 individuals with solute carrier family 6 member 1 variants, the vast majority of which are likely to lead to GABA transporter protein type 1 loss-of-function. The knowledge acquired will guide therapeutic decisions and the development of targeted therapies that selectively enhance transporter function and may improve symptoms. We analysed the longitudinal and cell type-specific expression of solute carrier family 6 member 1 in humans and localization of patient and control missense variants in a novel GABA transporter protein type 1 protein structure model. In this update, we discuss the progress made in understanding and treating solute carrier family 6 member 1-related disorders thus far, through the concerted efforts of clinicians, scientists and family support groups.
Collapse
Affiliation(s)
- Kimberly Goodspeed
- Children's Health, Medical Center, UT Southwestern, Dallas, TX 75235, USA
- Department of Pediatrics, Medical Center, UT Southwestern, Dallas, TX 75235, USA
| | - Eduardo Pérez-Palma
- Genomic Medicine Institute, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44195, USA
| | - Sumaiya Iqbal
- Broad Institute of MIT and Harvard, Stanley Center for Psychiatric Research, Cambridge, MA 02142, USA
- Broad Institute of MIT and Harvard, Center for Development of Therapeutics, Cambridge, MA 02142, USA
| | - Dominique Cooper
- Children's Health, Medical Center, UT Southwestern, Dallas, TX 75235, USA
| | - Annalisa Scimemi
- Department of Biological Sciences, University at Albany, Albany, NY 12222, USA
| | - Katrine M Johannesen
- Department of Epilepsy Genetics and Personalized Treatment, Danish Epilepsy Center Filadelfia, Dianalund 4293, Denmark
- Department of Regional Health Research, Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Arthur Stefanski
- Genomic Medicine Institute, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44195, USA
| | - Scott Demarest
- Departments of Pediatrics and Neurology, University of Colorado School of Medicine, Aurora, CO, USA
- Department of Pediatric Neurology and Neuroscience Institute, Children's Hospital Colorado, Aurora, CO, USA
| | - Katherine L Helbig
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- The Epilepsy NeuroGenetics Initiative (ENGIN), Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Department of Biomedical and Health Informatics (DBHi), Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Jingqiong Kang
- Department of Neurology, Vanderbilt University Medical Center, TN 37232, USA
| | - Frances C Shaffo
- Department of Pediatrics, Medical Center, UT Southwestern, Dallas, TX 75235, USA
| | | | - Catherine A Brownstein
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Byungchan Lim
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Hospital, Seoul 03080, Republic of Korea
| | - Ingo Helbig
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- The Epilepsy NeuroGenetics Initiative (ENGIN), Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Department of Biomedical and Health Informatics (DBHi), Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Emily De Los Reyes
- Department of Pediatric Neurology, Nationwide Children's Hospital, Columbus, OH, USA
- The Ohio State University College of Medicine, Columbus, OH, USA
| | | | - Vincenzo Crunelli
- Neuroscience Division, School of Bioscience, Cardiff University, Cardiff, UK
- Faculty of Medicine and Surgery, Malta University, Msida, Malta
| | - Arthur J Campbell
- Broad Institute of MIT and Harvard, Stanley Center for Psychiatric Research, Cambridge, MA 02142, USA
- Broad Institute of MIT and Harvard, Center for Development of Therapeutics, Cambridge, MA 02142, USA
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Treatment, Danish Epilepsy Center Filadelfia, Dianalund 4293, Denmark
- Department of Regional Health Research, Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Amber Freed
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Dennis Lal
- Genomic Medicine Institute, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44195, USA
- Broad Institute of MIT and Harvard, Stanley Center for Psychiatric Research, Cambridge, MA 02142, USA
- Neurological Institute, Epilepsy Center, Cleveland Clinic, Cleveland, OH 44195, USA
| |
Collapse
|
13
|
Serrano-Regal MP, Bayón-Cordero L, Ordaz RP, Garay E, Limon A, Arellano RO, Matute C, Sánchez-Gómez MV. Expression and Function of GABA Receptors in Myelinating Cells. Front Cell Neurosci 2020; 14:256. [PMID: 32973453 PMCID: PMC7472887 DOI: 10.3389/fncel.2020.00256] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 07/24/2020] [Indexed: 01/14/2023] Open
Abstract
Myelin facilitates the fast transmission of nerve impulses and provides metabolic support to axons. Differentiation of oligodendrocyte progenitor cells (OPCs) and Schwann cell (SC) precursors is critical for myelination during development and myelin repair in demyelinating disorders. Myelination is tightly controlled by neuron-glia communication and requires the participation of a wide repertoire of signals, including neurotransmitters such as glutamate, ATP, adenosine, or γ-aminobutyric acid (GABA). GABA is the main inhibitory neurotransmitter in the central nervous system (CNS) and it is also present in the peripheral nervous system (PNS). The composition and function of GABA receptors (GABARs) are well studied in neurons, while their nature and role in glial cells are still incipient. Recent studies demonstrate that GABA-mediated signaling mechanisms play relevant roles in OPC and SC precursor development and function, and stand out the implication of GABARs in oligodendrocyte (OL) and SC maturation and myelination. In this review, we highlight the evidence supporting the novel role of GABA with an emphasis on the molecular identity of the receptors expressed in these glial cells and the possible signaling pathways involved in their actions. GABAergic signaling in myelinating cells may have potential implications for developing novel reparative therapies in demyelinating diseases.
Collapse
Affiliation(s)
- Mari Paz Serrano-Regal
- Laboratory of Neurobiology, Achucarro Basque Center for Neuroscience, Leioa, Spain
- Department of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
| | - Laura Bayón-Cordero
- Laboratory of Neurobiology, Achucarro Basque Center for Neuroscience, Leioa, Spain
- Department of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
| | - Rainald Pablo Ordaz
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Mexico
| | - Edith Garay
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Mexico
| | - Agenor Limon
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, TX, United States
| | - Rogelio O. Arellano
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Mexico
| | - Carlos Matute
- Laboratory of Neurobiology, Achucarro Basque Center for Neuroscience, Leioa, Spain
- Department of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
| | - María Victoria Sánchez-Gómez
- Laboratory of Neurobiology, Achucarro Basque Center for Neuroscience, Leioa, Spain
- Department of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
| |
Collapse
|
14
|
Łątka K, Jończyk J, Bajda M. γ-Aminobutyric acid transporters as relevant biological target: Their function, structure, inhibitors and role in the therapy of different diseases. Int J Biol Macromol 2020; 158:S0141-8130(20)32987-1. [PMID: 32360967 DOI: 10.1016/j.ijbiomac.2020.04.126] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 04/17/2020] [Accepted: 04/18/2020] [Indexed: 12/13/2022]
Abstract
γ-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the nervous system. It plays a crucial role in many physiological processes. Upon release from the presynaptic element, it is removed from the synaptic cleft by reuptake due to the action of GABA transporters (GATs). GATs belong to a large SLC6 protein family whose characteristic feature is sodium-dependent relocation of neurotransmitters through the cell membrane. GABA transporters are characterized in many contexts, but their spatial structure is not fully known. They are divided into four types, which differ in occurrence and role. Herein, the special attention was paid to these transporting proteins. This comprehensive review presents the current knowledge about GABA transporters. Their distribution in the body, physiological functions and possible utilization in the therapy of different diseases were fully discussed. The important structural features were described based on published data, including sequence analysis, mutagenesis studies, and comparison with known SLC6 transporters for leucine (LeuT), dopamine (DAT) and serotonin (SERT). Moreover, the most important inhibitors of GABA transporters of various basic scaffolds, diverse selectivity and potency were presented.
Collapse
Affiliation(s)
- Kamil Łątka
- Jagiellonian University Medical College, Faculty of Pharmacy, Department of Physicochemical Drug Analysis, 30-688 Cracow, Medyczna 9, Poland
| | - Jakub Jończyk
- Jagiellonian University Medical College, Faculty of Pharmacy, Department of Physicochemical Drug Analysis, 30-688 Cracow, Medyczna 9, Poland
| | - Marek Bajda
- Jagiellonian University Medical College, Faculty of Pharmacy, Department of Physicochemical Drug Analysis, 30-688 Cracow, Medyczna 9, Poland.
| |
Collapse
|
15
|
Fattorini G, Melone M, Conti F. A Reappraisal of GAT-1 Localization in Neocortex. Front Cell Neurosci 2020; 14:9. [PMID: 32116556 PMCID: PMC7031676 DOI: 10.3389/fncel.2020.00009] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 01/13/2020] [Indexed: 12/31/2022] Open
Abstract
γ-Aminobutyric acid (GABA) transporter (GAT)-1, the major GABA transporter in the brain, plays a key role in modulating GABA signaling and is involved in the pathophysiology of several neuropsychiatric diseases, including epilepsy. The original description of GAT-1 as a neuronal transporter has guided the interpretation of the findings of all physiological, pharmacological, genetic, or clinical studies. However, evidence published in the past few years, some of which is briefly reviewed herein, does not seem to be consistent with a neurocentric view of GAT-1 function and calls for more detailed analysis of its localization. We therefore performed a thorough systematic assessment of GAT-1 localization in neocortex and subcortical white matter. In line with earlier work, we found that GAT-1 was robustly expressed in axon terminals forming symmetric synapses and in astrocytic processes, whereas its astrocytic expression was more diffuse than expected and, even more surprisingly, immature and mature oligodendrocytes and microglial cells also expressed the transporter. These data indicate that the era of “neuronal” and “glial” GABA transporters has finally come to a close and provide a wider perspective from which to view GABA-mediated physiological phenomena. In addition, given the well-known involvement of astrocytes, oligodendrocytes, and microglial cells in physiological as well as pathological conditions, the demonstration of functional GAT-1 in these cells is expected to provide greater insight into the phenomena occurring in the diseased brain as well as to prompt a reassessment of earlier findings.
Collapse
Affiliation(s)
- Giorgia Fattorini
- Department of Experimental and Clinical Medicine, Faculty of Medicine and Surgery, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy
| | - Marcello Melone
- Department of Experimental and Clinical Medicine, Faculty of Medicine and Surgery, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy
| | - Fiorenzo Conti
- Department of Experimental and Clinical Medicine, Faculty of Medicine and Surgery, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy.,Fondazione di Medicina Molecolare, Università Politecnica delle Marche, Ancona, Italy
| |
Collapse
|
16
|
Fattorini G, Catalano M, Melone M, Serpe C, Bassi S, Limatola C, Conti F. Microglial expression of GAT-1 in the cerebral cortex. Glia 2019; 68:646-655. [PMID: 31692106 DOI: 10.1002/glia.23745] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 10/12/2019] [Accepted: 10/18/2019] [Indexed: 01/08/2023]
Abstract
Microglial cells are the immune cells of the brain that, by sensing the microenvironment, permit a correct brain development and function. They communicate with other glial cells and with neurons, releasing and responding to a number of molecules that exert effects on surrounding cells. Among these, neurotransmitters and, in particular, gamma-aminobutyric acid (GABA) has recently gained interest in this context. We demonstrated the expression of GABA transporter 1 (GAT-1) in microglial cells both in soma and cell processes. We show that microglial cell treatment with 1,2,5,6-tetrahydro-1-[2-[[(diphenylmethylene)amino]oxy]ethyl]-3-pyridinecarboxylic acid hydrochloride (NNC-711), a potent and selective GAT-1 inhibitor, significantly reduced Na+ -dependent GABA uptake. On the other hand, GABA uptake was significantly increased by cell treatment with (S)-1-[2-[tris(4-methoxyphenyl)methoxy]ethyl]-3-piperidinecarboxylic acid (SNAP-5114), a GAT-2/3 inhibitor, and this effect was completely blocked by the botulinum toxin BoNT/C1, that specifically cleaves and inactives syntaxin 1A (STX1A). Overall, these findings show that microglial cells express GAT-1 and indicate that STX1A plays an important role in the regulation of GAT-1-dependent GABA uptake in microglia.
Collapse
Affiliation(s)
- Giorgia Fattorini
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy
| | - Myriam Catalano
- Department of Physiology and Pharmacology, Sapienza University of Rome, Laboratory Affiliated to Istituto Pasteur Italia, Rome, Italy
| | - Marcello Melone
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy
| | - Carmela Serpe
- Department of Physiology and Pharmacology, Sapienza University of Rome, Laboratory Affiliated to Istituto Pasteur Italia, Rome, Italy
| | - Silvia Bassi
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
| | - Cristina Limatola
- Department of Physiology and Pharmacology, Sapienza University of Rome, Laboratory Affiliated to Istituto Pasteur Italia, Rome, Italy.,IRCCS Neuromed, Via Atinense, Pozzilli, Italy
| | - Fiorenzo Conti
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy
| |
Collapse
|
17
|
Serrano-Regal MP, Luengas-Escuza I, Bayón-Cordero L, Ibarra-Aizpurua N, Alberdi E, Pérez-Samartín A, Matute C, Sánchez-Gómez MV. Oligodendrocyte Differentiation and Myelination Is Potentiated via GABA B Receptor Activation. Neuroscience 2019; 439:163-180. [PMID: 31349008 DOI: 10.1016/j.neuroscience.2019.07.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 02/07/2023]
Abstract
Differentiation of oligodendrocyte precursor cells (OPCs) into mature oligodendrocytes (OLs) is a key event for axonal myelination in the central nervous system (CNS). Several growth factors and neurotransmitters like GABA are postulated as important regulators of that process, and different protein kinases may also participate in OL differentiation and myelination. However, the molecular mechanisms underlying the regulation of myelination by neurotransmitters are only partially known. In the present study, we provide evidence showing that GABA receptors (GABARs) play an important role in OL differentiation. First, we observed that OPCs and OLs synthesize GABA and expressed GABAR and transporters, both in vitro and in vivo and, in contrast to GABAARs, the subunits GABAB1R and GABAB2R are expressed in OLs over time. Then, we found that exogenous GABA increases the number of myelin segments and MBP expression in DRG-OPC cocultures, indicating that GABA regulates myelination when OLs are in contact with axons. Notably, in purified rat OPC cultures, chronic treatment with GABA and baclofen, specific GABABR agonist, accelerates OPC differentiation by enhancing the processes branching and myelin protein expression, effects that are reverted in presence of GABABR specific antagonist CGP55845. Exposure of OPCs to baclofen promotes the Src-phosphorylation, and the baclofen-induced maturation is attenuated in presence of the Src-family kinases inhibitor PP2. None of these effects are mediated by the GABAAR agonist muscimol. Together, these results highlight the relevance of the GABAergic system in OL differentiation, and indicate that this functional role is mediated through GABABR involving the participation of Src-family kinases. This article is part of a Special Issue entitled: Honoring Ricardo Miledi - outstanding neuroscientist of XX-XXI centuries.
Collapse
Affiliation(s)
- Mari Paz Serrano-Regal
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain; Achucarro Basque Center for Neuroscience, Leioa, Spain; Centro de Investigación en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
| | - Irene Luengas-Escuza
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Laura Bayón-Cordero
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Naroa Ibarra-Aizpurua
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Elena Alberdi
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain; Achucarro Basque Center for Neuroscience, Leioa, Spain; Centro de Investigación en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
| | - Alberto Pérez-Samartín
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain; Achucarro Basque Center for Neuroscience, Leioa, Spain; Centro de Investigación en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
| | - Carlos Matute
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain; Achucarro Basque Center for Neuroscience, Leioa, Spain; Centro de Investigación en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain.
| | - María Victoria Sánchez-Gómez
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain; Achucarro Basque Center for Neuroscience, Leioa, Spain; Centro de Investigación en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain.
| |
Collapse
|
18
|
Hammann J, Bassetti D, White R, Luhmann HJ, Kirischuk S. α2 isoform of Na +,K +-ATPase via Na +,Ca 2+ exchanger modulates myelin basic protein synthesis in oligodendrocyte lineage cells in vitro. Cell Calcium 2018; 73:1-10. [PMID: 29880193 DOI: 10.1016/j.ceca.2018.03.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/05/2018] [Accepted: 03/25/2018] [Indexed: 11/26/2022]
Abstract
Oligodendrocytes in the CNS myelinate neuronal axons, facilitating rapid propagation of action potentials. Myelin basic protein (MBP) is an essential component of myelin and its absence results in severe hypomyelination. In oligodendrocyte lineage cell (OLC) monocultures MBP synthesis starts at DIV4. Ouabain (10 nM), a Na+,K+-ATPase (NKA) blocker, stimulates MBP synthesis. As OLCs express the α2 isoform of NKA (α2-NKA) that has a high affinity for ouabain, we hypothesized that α2-NKA mediates this effect. Knockdown of α2-NKA with small interfering (si)RNA (α2-siRNA) significantly potentiated MBP synthesis at DIV4 and 5. This effect was completely blocked by KB-R7943 (1 μM), a Na+,Ca2+ exchanger (NCX) antagonist. α2-NKA ablation increased the frequency of NCX-mediated spontaneous Ca2+ transients ([Ca2+]t) at DIV4, whereas in control OLC cultures comparable frequency of [Ca2+]t was observed at DIV5. At DIV6 almost no [Ca2+]t were observed either in control or in α2-siRNA-treated cultures. Immunocytochemical analyses showed that α2-NKA co-localizes with MBP in proximal processes of immature OLCs but is only weakly present in MBP-enriched membrane sheets. Knockdown of α2-NKA in cortical slice cultures did not change MBP levels but reduced co-localization of neurofilament- and MBP-positive compartments. We conclude that α2-NKA activity in OLCs affects NCX-mediated [Ca2+]t and the onset of MBP synthesis. We suggest therefore that neuronal activity, presumably in form of local extracellular [K+] changes, might locally influence NCX-mediated [Ca2+]t in OLC processes thus triggering local MBP synthesis in the vicinity of an active axon.
Collapse
Affiliation(s)
- Jens Hammann
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz, Germany
| | - Davide Bassetti
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz, Germany
| | - Robin White
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz, Germany
| | - Heiko J Luhmann
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz, Germany
| | - Sergei Kirischuk
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz, Germany.
| |
Collapse
|
19
|
Pacific Ciguatoxin Induces Excitotoxicity and Neurodegeneration in the Motor Cortex Via Caspase 3 Activation: Implication for Irreversible Motor Deficit. Mol Neurobiol 2018; 55:6769-6787. [DOI: 10.1007/s12035-018-0875-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 01/07/2018] [Indexed: 12/14/2022]
|
20
|
Brown DA. Norman Bowery's discoveries about extrasynaptic and asynaptic GABA systems and their significance. Neuropharmacology 2017; 136:3-9. [PMID: 29128306 DOI: 10.1016/j.neuropharm.2017.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 11/04/2017] [Indexed: 11/26/2022]
Abstract
Before discovering the GABA-B receptor, Norman Bowery completed a series of studies on an extrasynaptic or asynaptic "GABA system" in the rat superior cervical sympathetic ganglion. First, he discovered an uptake system for GABA in neuroglial cells in the ganglia and in peripheral nerves, with a different substrate specificity than that in neurons. Second, he showed that accumulated GABA in sympathetic glial cells was metabolized to succinate by a transaminase enzyme. Third, he provided detailed structure-activity information about compounds activating an extrasynaptic GABA-A receptor on neurons in the rat sympathetic ganglion. Fourth, he showed that some amino acid substrates for the neuroglial transporter could indirectly stimulate neurons by releasing GABA from adjacent glial cells, and that GABA could also be released from neuroglial cells by membrane depolarization. In this review, these discoveries are briefly described and updated and some of their implications assessed. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
Collapse
Affiliation(s)
- David A Brown
- Department of Neuroscience, Physiology & Pharmacology, University College London, London WC1E 6BT, UK.
| |
Collapse
|