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Terradillos I, Bonilla-Del Río I, Puente N, Serrano M, Mimenza A, Lekunberri L, Anaut-Lusar I, Reguero L, Gerrikagoitia I, Ruiz de Martín Esteban S, Hillard CJ, Grande MT, Romero J, Elezgarai I, Grandes P. Altered glial expression of the cannabinoid 1 receptor in the subiculum of a mouse model of Alzheimer's disease. Glia 2023; 71:866-879. [PMID: 36437738 DOI: 10.1002/glia.24312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 10/23/2022] [Accepted: 11/18/2022] [Indexed: 11/29/2022]
Abstract
The alteration of the endocannabinoid tone usually associates with changes in the expression and/or function of the cannabinoid CB1 receptor. In Alzheimer's disease (AD), amyloid beta (Aβ)-containing aggregates induce a chronic inflammatory response leading to reactivity of both microglia and astrocytes. However, how this glial response impacts on the glial CB1 receptor expression in the subiculum of a mouse model of AD, a brain region particularly affected by large accumulation of plaques and concomitant subcellular changes in microglia and astrocytes, is unknown. The CB1 receptor localization in both glial cells was investigated in the subiculum of male 5xFAD/CB2 EGFP/f/f (AD model) and CB2 EGFP/f/f mice by immuno-electron microscopy. The findings revealed that glial CB1 receptors suffer remarkable changes in the AD mouse. Thus, CB1 receptor expression increases in reactive microglia in 5xFAD/CB2 EGFP/f/f , but remains constant in astrocytes with CB1 receptor labeling rising proportionally to the perimeter of the reactive astrocytes. Not least, the CB1 receptor localization in microglial processes in the subiculum of controls and closely surrounding amyloid plaques and dystrophic neurites of the AD model, supports previous suggestions of the presence of the CB1 receptor in microglia. These findings on the correlation between glial reactivity and the CB1 receptor expression in microglial cells and astrocytes, contribute to the understanding of the role of the endocannabinoid system in the pathophysiology of Alzheimer's disease.
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Affiliation(s)
- Itziar Terradillos
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Leioa, Spain.,Achucarro Basque Center for Neuroscience, Leioa, Spain
| | - Itziar Bonilla-Del Río
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Leioa, Spain.,Achucarro Basque Center for Neuroscience, Leioa, Spain
| | - Nagore Puente
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Leioa, Spain.,Achucarro Basque Center for Neuroscience, Leioa, Spain
| | - Maitane Serrano
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Leioa, Spain.,Achucarro Basque Center for Neuroscience, Leioa, Spain
| | - Amaia Mimenza
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Leioa, Spain.,Achucarro Basque Center for Neuroscience, Leioa, Spain
| | - Leire Lekunberri
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Leioa, Spain.,Achucarro Basque Center for Neuroscience, Leioa, Spain
| | - Ilazki Anaut-Lusar
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Leioa, Spain.,Achucarro Basque Center for Neuroscience, Leioa, Spain
| | - Leire Reguero
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Leioa, Spain.,Achucarro Basque Center for Neuroscience, Leioa, Spain
| | - Inmaculada Gerrikagoitia
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Leioa, Spain.,Achucarro Basque Center for Neuroscience, Leioa, Spain
| | | | - Cecilia J Hillard
- Department of Pharmacology and Toxicology, Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - María T Grande
- Faculty of Experimental Sciences, Universidad Francisco de Vitoria, Pozuelo de Alarcón, Spain
| | - Julián Romero
- Faculty of Experimental Sciences, Universidad Francisco de Vitoria, Pozuelo de Alarcón, Spain
| | - Izaskun Elezgarai
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Leioa, Spain.,Achucarro Basque Center for Neuroscience, Leioa, Spain
| | - Pedro Grandes
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Leioa, Spain.,Achucarro Basque Center for Neuroscience, Leioa, Spain
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2
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Krassner MM, Kauffman J, Sowa A, Cialowicz K, Walsh S, Farrell K, Crary JF, McKenzie AT. Postmortem changes in brain cell structure: a review. FREE NEUROPATHOLOGY 2023; 4:4-10. [PMID: 37384330 PMCID: PMC10294569 DOI: 10.17879/freeneuropathology-2023-4790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 05/15/2023] [Indexed: 06/30/2023]
Abstract
Brain cell structure is a key determinant of neural function that is frequently altered in neurobiological disorders. Following the global loss of blood flow to the brain that initiates the postmortem interval (PMI), cells rapidly become depleted of energy and begin to decompose. To ensure that our methods for studying the brain using autopsy tissue are robust and reproducible, there is a critical need to delineate the expected changes in brain cell morphometry during the PMI. We searched multiple databases to identify studies measuring the effects of PMI on the morphometry (i.e. external dimensions) of brain cells. We screened 2119 abstracts, 361 full texts, and included 172 studies. Mechanistically, fluid shifts causing cell volume alterations and vacuolization are an early event in the PMI, while the loss of the ability to visualize cell membranes altogether is a later event. Decomposition rates are highly heterogenous and depend on the methods for visualization, the structural feature of interest, and modifying variables such as the storage temperature or the species. Geometrically, deformations of cell membranes are common early events that initiate within minutes. On the other hand, topological relationships between cellular features appear to remain intact for more extended periods. Taken together, there is an uncertain period of time, usually ranging from several hours to several days, over which cell membrane structure is progressively lost. This review may be helpful for investigators studying human postmortem brain tissue, wherein the PMI is an unavoidable aspect of the research.
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Affiliation(s)
- Margaret M. Krassner
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Friedman Brain Institute, Departments of Pathology, Neuroscience and Artificial Intelligence & Human Health, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Neuropathology Brain Bank & Research Core and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Justin Kauffman
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Friedman Brain Institute, Departments of Pathology, Neuroscience and Artificial Intelligence & Human Health, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Neuropathology Brain Bank & Research Core and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Allison Sowa
- Microscopy and Advanced Bioimaging Core, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Katarzyna Cialowicz
- Microscopy and Advanced Bioimaging Core, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Samantha Walsh
- Hunter College Libraries, CUNY Hunter College, New York, NY
| | - Kurt Farrell
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Friedman Brain Institute, Departments of Pathology, Neuroscience and Artificial Intelligence & Human Health, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Neuropathology Brain Bank & Research Core and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - John F. Crary
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Friedman Brain Institute, Departments of Pathology, Neuroscience and Artificial Intelligence & Human Health, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Neuropathology Brain Bank & Research Core and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Andrew T. McKenzie
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Friedman Brain Institute, Departments of Pathology, Neuroscience and Artificial Intelligence & Human Health, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Neuropathology Brain Bank & Research Core and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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3
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Y Yeung JH, Waldvogel HJ, M Faull RL, Kwakowsky A. iGluR expression in the hippocampal formation, entorhinal cortex, and superior temporal gyrus in Alzheimer's disease. Neural Regen Res 2022; 17:2197-2199. [PMID: 35259829 PMCID: PMC9083167 DOI: 10.4103/1673-5374.335804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Jason H Y Yeung
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Henry J Waldvogel
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Richard L M Faull
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Andrea Kwakowsky
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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4
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Rodríguez-Campuzano AG, Ortega A. Glutamate transporters: Critical components of glutamatergic transmission. Neuropharmacology 2021; 192:108602. [PMID: 33991564 DOI: 10.1016/j.neuropharm.2021.108602] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/09/2021] [Accepted: 04/27/2021] [Indexed: 02/06/2023]
Abstract
Glutamate is the major excitatory neurotransmitter in the vertebrate central nervous system. Once released, it binds to specific membrane receptors and transporters activating a wide variety of signal transduction cascades, as well as its removal from the synaptic cleft in order to avoid its extracellular accumulation and the overstimulation of extra-synaptic receptors that might result in neuronal death through a process known as excitotoxicity. Although neurodegenerative diseases are heterogenous in clinical phenotypes and genetic etiologies, a fundamental mechanism involved in neuronal degeneration is excitotoxicity. Glutamate homeostasis is critical for brain physiology and Glutamate transporters are key players in maintaining low extracellular Glutamate levels. Therefore, the characterization of Glutamate transporters has been an active area of glutamatergic research for the last 40 years. Transporter activity its regulated at different levels: transcriptional and translational control, transporter protein trafficking and membrane mobility, and through extensive post-translational modifications. The elucidation of these mechanisms has emerged as an important piece to shape our current understanding of glutamate actions in the nervous system.
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Affiliation(s)
- Ada G Rodríguez-Campuzano
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, Ciudad de México, 07000, Mexico
| | - Arturo Ortega
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, Ciudad de México, 07000, Mexico.
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5
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Danbolt NC, López-Corcuera B, Zhou Y. Reconstitution of GABA, Glycine and Glutamate Transporters. Neurochem Res 2021; 47:85-110. [PMID: 33905037 PMCID: PMC8763731 DOI: 10.1007/s11064-021-03331-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/13/2021] [Accepted: 04/15/2021] [Indexed: 10/25/2022]
Abstract
In contrast to water soluble enzymes which can be purified and studied while in solution, studies of solute carrier (transporter) proteins require both that the protein of interest is situated in a phospholipid membrane and that this membrane forms a closed compartment. An additional challenge to the study of transporter proteins has been that the transport depends on the transmembrane electrochemical gradients. Baruch I. Kanner understood this early on and first developed techniques for studying plasma membrane vesicles. This advanced the field in that the experimenter could control the electrochemical gradients. Kanner, however, did not stop there, but started to solubilize the membranes so that the transporter proteins were taken out of their natural environment. In order to study them, Kanner then had to find a way to reconstitute them (reinsert them into phospholipid membranes). The scope of the present review is both to describe the reconstitution method in full detail as that has never been done, and also to reveal the scientific impact that this method has had. Kanner's later work is not reviewed here although that also deserves a review because it too has had a huge impact.
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Affiliation(s)
- Niels Christian Danbolt
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway.
| | - Beatriz López-Corcuera
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Madrid, Spain.,Centro de Biología Molecular "Severo Ochoa" Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain.,IdiPAZ, Hospital Universitario La Paz, Madrid, Spain
| | - Yun Zhou
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway
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6
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Dhaher R, Gruenbaum SE, Sandhu MRS, Ottestad-Hansen S, Tu N, Wang Y, Lee TSW, Deshpande K, Spencer DD, Danbolt NC, Zaveri HP, Eid T. Network-Related Changes in Neurotransmitters and Seizure Propagation During Rodent Epileptogenesis. Neurology 2021; 96:e2261-e2271. [PMID: 33722994 PMCID: PMC8166437 DOI: 10.1212/wnl.0000000000011846] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 01/29/2021] [Indexed: 12/24/2022] Open
Abstract
OBJECTIVE To test the hypothesis that glutamate and GABA are linked to the formation of epilepsy networks and the triggering of spontaneous seizures, we examined seizure initiation/propagation characteristics and neurotransmitter levels during epileptogenesis in a translationally relevant rodent model of mesial temporal lobe epilepsy. METHODS The glutamine synthetase (GS) inhibitor methionine sulfoximine was infused into one of the hippocampi in laboratory rats to create a seizure focus. Long-term video-intracranial EEG recordings and brain microdialysis combined with mass spectrometry were used to examine seizure initiation, seizure propagation, and extracellular brain levels of glutamate and GABA. RESULTS All seizures (n = 78 seizures, n = 3 rats) appeared first in the GS-inhibited hippocampus of all animals, followed by propagation to the contralateral hippocampus. Propagation time decreased significantly from 11.65 seconds early in epileptogenesis (weeks 1-2) to 6.82 seconds late in epileptogenesis (weeks 3-4, paired t test, p = 0.025). Baseline extracellular glutamate levels were 11.6-fold higher in the hippocampus of seizure propagation (7.3 µM) vs the hippocampus of seizure onset (0.63 µM, analysis of variance/Fisher least significant difference, p = 0.01), even though the concentrations of the major glutamate transporter proteins excitatory amino acid transporter subtypes 1 and 2 and xCT were unchanged between the brain regions. Finally, extracellular GABA in the seizure focus decreased significantly from baseline several hours before a spontaneous seizure (paired t test/false discovery rate). CONCLUSION The changes in glutamate and GABA suggest novel and potentially important roles of the amino acids in epilepsy network formation and in the initiation and propagation of spontaneous seizures.
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Affiliation(s)
- Roni Dhaher
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Shaun E Gruenbaum
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Mani Ratnesh S Sandhu
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Sigrid Ottestad-Hansen
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Nathan Tu
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Yue Wang
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Tih-Shih W Lee
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Ketaki Deshpande
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Dennis D Spencer
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Niels Christian Danbolt
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Hitten P Zaveri
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Tore Eid
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway.
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7
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Hu QX, Klatt GM, Gudmundsrud R, Ottestad-Hansen S, Verbruggen L, Massie A, Danbolt NC, Zhou Y. Semi-quantitative distribution of excitatory amino acid (glutamate) transporters 1–3 (EAAT1-3) and the cystine-glutamate exchanger (xCT) in the adult murine spinal cord. Neurochem Int 2020; 140:104811. [DOI: 10.1016/j.neuint.2020.104811] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/21/2020] [Accepted: 07/09/2020] [Indexed: 01/01/2023]
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8
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Potassium and glutamate transport is impaired in scar-forming tumor-associated astrocytes. Neurochem Int 2019; 133:104628. [PMID: 31825815 PMCID: PMC6957761 DOI: 10.1016/j.neuint.2019.104628] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 12/04/2019] [Accepted: 12/05/2019] [Indexed: 01/09/2023]
Abstract
Unprovoked recurrent seizures are a serious comorbidity affecting most patients who suffer from glioma, a primary brain tumor composed of malignant glial cells. Cellular mechanisms contributing to the development of recurrent spontaneous seizures include the release of the excitatory neurotransmitter glutamate from glioma into extracellular space. Under physiological conditions, astrocytes express two high affinity glutamate transporters, Glt-1 and Glast, which are responsible for the removal of excess extracellular glutamate. In the context of neurological disease or brain injury, astrocytes become reactive which can negatively affect neuronal function, causing hyperexcitability and/or death. Using electrophysiology, immunohistochemistry, fluorescent in situ hybridization, and Western blot analysis in different orthotopic xenograft and allograft models of human and mouse gliomas, we find that peritumoral astrocytes exhibit astrocyte scar formation characterized by proliferation, cellular hypertrophy, process elongation, and increased GFAP and pSTAT3. Overall, peritumoral reactive astrocytes show a significant reduction in glutamate and potassium uptake, as well as decreased glutamine synthetase activity. A subset of peritumoral astrocytes displayed a depolarized resting membrane potential, further contributing to reduced potassium and glutamate homeostasis. These changes may contribute to the propagation of peritumoral neuronal hyperexcitability and excitotoxic death.
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9
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Eid T, Lee TSW, Patrylo P, Zaveri HP. Astrocytes and Glutamine Synthetase in Epileptogenesis. J Neurosci Res 2019; 97:1345-1362. [PMID: 30022509 PMCID: PMC6338538 DOI: 10.1002/jnr.24267] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 05/15/2018] [Accepted: 05/22/2018] [Indexed: 12/31/2022]
Abstract
The cellular, molecular, and metabolic mechanisms that underlie the development of mesial temporal lobe epilepsy are incompletely understood. Here we review the role of astrocytes in epilepsy development (a.k.a. epileptogenesis), particularly astrocyte pathologies related to: aquaporin 4, the inwardly rectifying potassium channel Kir4.1, monocarboxylate transporters MCT1 and MCT2, excitatory amino acid transporters EAAT1 and EAAT2, and glutamine synthetase. We propose that inhibition, dysfunction or loss of astrocytic glutamine synthetase is an important causative factor for some epilepsies, particularly mesial temporal lobe epilepsy and glioblastoma-associated epilepsy. We postulate that the regulatory mechanisms of glutamine synthetase as well as the downstream effects of glutamine synthetase dysfunction, represent attractive, new targets for antiepileptogenic interventions. Currently, no antiepileptogenic therapies are available for human use. The discovery of such interventions is important as it will fundamentally change the way we approach epilepsy by preventing the disease from ever becoming manifest after an epileptogenic insult to the brain.
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Affiliation(s)
- Tore Eid
- Department of Laboratory Medicine, Yale School of Medicine
- Department of Molecular Medicine, University of Oslo
| | | | - Peter Patrylo
- Department of Physiology, Southern Illinois University School of Medicine
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10
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Zhou Y, Dhaher R, Parent M, Hu QX, Hassel B, Yee SP, Hyder F, Gruenbaum SE, Eid T, Danbolt NC. Selective deletion of glutamine synthetase in the mouse cerebral cortex induces glial dysfunction and vascular impairment that precede epilepsy and neurodegeneration. Neurochem Int 2018; 123:22-33. [PMID: 30053506 DOI: 10.1016/j.neuint.2018.07.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 07/22/2018] [Accepted: 07/23/2018] [Indexed: 12/31/2022]
Abstract
Glutamate-ammonia ligase (glutamine synthetase; Glul) is enriched in astrocytes and serves as the primary enzyme for ammonia detoxification and glutamate inactivation in the brain. Loss of astroglial Glul is reported in hippocampi of epileptic patients, but the mechanism by which Glul deficiency might cause disease remains elusive. Here we created a novel mouse model by selectively deleting Glul in the hippocampus and neocortex. The Glul deficient mice were born without any apparent malformations and behaved unremarkably until postnatal week three. There were reductions in tissue levels of aspartate, glutamate, glutamine and GABA and in mRNA encoding glutamate receptor subunits GRIA1 and GRIN2A as well as in the glutamate transporter proteins EAAT1 and EAAT2. Adult Glul-deficient mice developed progressive neurodegeneration and spontaneous seizures which increased in frequency with age. Importantly, progressive astrogliosis occurred before neurodegeneration and was first noted in astrocytes along cerebral blood vessels. The responses to CO2-provocation were attenuated at four weeks of age and dilated microvessels were observed histologically in sclerotic areas of cKO. Thus, the abnormal glutamate metabolism observed in this model appeared to cause epilepsy by first inducing gliopathy and disrupting the neurovascular coupling.
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Affiliation(s)
- Yun Zhou
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, N-0317, Oslo, Norway.
| | - Roni Dhaher
- Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT, 06520, USA
| | - Maxime Parent
- Magnetic Resonance Research Center, Yale School of Medicine, New Haven, CT, 06520, USA
| | - Qiu-Xiang Hu
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, N-0317, Oslo, Norway
| | - Bjørnar Hassel
- Department of Complex Neurology and Neurohabilitation, Oslo University Hospital, University of Oslo, N-0450, Oslo, Norway
| | - Siu-Pok Yee
- Department of Cell Biology, University of Connecticut Health, Farmington, CT, 06030, USA
| | - Fahmeed Hyder
- Magnetic Resonance Research Center, Yale School of Medicine, New Haven, CT, 06520, USA
| | - Shaun E Gruenbaum
- Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT, 06520, USA
| | - Tore Eid
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, N-0317, Oslo, Norway; Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT, 06520, USA.
| | - Niels Christian Danbolt
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, N-0317, Oslo, Norway.
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11
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Albertini G, Deneyer L, Ottestad-Hansen S, Zhou Y, Ates G, Walrave L, Demuyser T, Bentea E, Sato H, De Bundel D, Danbolt NC, Massie A, Smolders I. Genetic deletion of xCT attenuates peripheral and central inflammation and mitigates LPS-induced sickness and depressive-like behavior in mice. Glia 2018; 66:1845-1861. [PMID: 29693305 DOI: 10.1002/glia.23343] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 04/04/2018] [Accepted: 04/05/2018] [Indexed: 12/18/2022]
Abstract
The communication between the immune and central nervous system (CNS) is affected in many neurological disorders. Peripheral injections of the endotoxin lipopolysaccharide (LPS) are widely used to study this communication: an LPS challenge leads to a biphasic syndrome that starts with acute sickness and is followed by persistent brain inflammation and chronic behavioral alterations such as depressive-like symptoms. In vitro, the response to LPS treatment has been shown to involve enhanced expression of system <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup><mml:mrow><mml:mi>x</mml:mi></mml:mrow> <mml:mrow><mml:mi>c</mml:mi></mml:mrow> <mml:mrow><mml:mo>-</mml:mo></mml:mrow> </mml:msubsup> </mml:math> . This cystine-glutamate antiporter, with xCT as specific subunit, represents the main glial provider of extracellular glutamate in mouse hippocampus. Here we injected male xCT knockout and wildtype mice with a single intraperitoneal dose of 5 mg/kg LPS. LPS-injection increased hippocampal xCT expression but did not alter the mainly astroglial localization of the xCT protein. Peripheral and central inflammation (as defined by cytokine levels and morphological activation of microglia) as well as LPS-induced sickness and depressive-like behavior were significantly attenuated in xCT-deficient mice compared with wildtype mice. Our study is the first to demonstrate the involvement of system <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup><mml:mrow><mml:mi>x</mml:mi></mml:mrow> <mml:mrow><mml:mi>c</mml:mi></mml:mrow> <mml:mrow><mml:mo>-</mml:mo></mml:mrow> </mml:msubsup> </mml:math> in peripheral and central inflammation in vivo and the potential therapeutic relevance of its inhibition in brain disorders characterized by peripheral and central inflammation, such as depression.
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Affiliation(s)
- Giulia Albertini
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Brussels, 1090, Belgium
| | - Lauren Deneyer
- Department of Pharmaceutical Biotechnology and Molecular Biology, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Brussels, 1090, Belgium
| | - Sigrid Ottestad-Hansen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, 0372, Norway
| | - Yun Zhou
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, 0372, Norway
| | - Gamze Ates
- Department of In Vitro Toxicology and Dermato-cosmetology, Vrije Universiteit Brussel, Brussels, 1090, Belgium
| | - Laura Walrave
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Brussels, 1090, Belgium
| | - Thomas Demuyser
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Brussels, 1090, Belgium
| | - Eduard Bentea
- Department of Pharmaceutical Biotechnology and Molecular Biology, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Brussels, 1090, Belgium
| | - Hideyo Sato
- Laboratory of Biochemistry and Molecular Biology, Department of Medical Technology, Niigata University, Niigata, 951-8518, Japan
| | - Dimitri De Bundel
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Brussels, 1090, Belgium
| | - Niels C Danbolt
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, 0372, Norway
| | - Ann Massie
- Department of Pharmaceutical Biotechnology and Molecular Biology, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Brussels, 1090, Belgium
| | - Ilse Smolders
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Brussels, 1090, Belgium
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12
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Axon-terminals expressing EAAT2 (GLT-1; Slc1a2) are common in the forebrain and not limited to the hippocampus. Neurochem Int 2018. [PMID: 29530756 DOI: 10.1016/j.neuint.2018.03.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The excitatory amino acid transporter type 2 (EAAT2) represents the major mechanism for removal of extracellular glutamate. In the hippocampus, there is some EAAT2 in axon-terminals, whereas most of the protein is found in astroglia. The functional importance of the neuronal EAAT2 is unknown, and it is debated whether EAAT2-expressing nerve terminals are present in other parts of the brain. Here we selectively deleted the EAAT2 gene in neurons (by crossing EAAT2-flox mice with synapsin 1-Cre mice in the C57B6 background). To reduce interference from astroglial EAAT2, we measured glutamate accumulation in crude tissue homogenates. EAAT2 proteins levels were measured by immunoblotting. Although synapsin 1-Cre mediated gene deletion only reduced the forebrain tissue content of EAAT2 protein to 95.5 ± 3.4% of wild-type (littermate) controls, the glutamate accumulation in homogenates of neocortex, hippocampus, striatum and thalamus were nevertheless diminished to, respectively, 54 ± 4, 46 ± 3, 46 ± 2 and 65 ± 7% of controls (average ± SEM, n = 3 pairs of littermates). GABA uptake was unaffected. After injection of U-13C-glucose, lack of neuronal EAAT2 resulted in higher 13C-labeling of glutamine and GABA in the hippocampus suggesting that neuronal EAAT2 is partly short-circuiting the glutamate-glutamine cycle in wild-type mice. Crossing synapsin 1-Cre mice with Ai9 reporter mice revealed that Cre-mediated excision occurred efficiently in hippocampus CA3, but less efficiently in other regions and hardly at all in the cerebellum. Conclusions: (1) EAAT2 is expressed in nerve terminals in multiple brain regions. (2) The uptake catalyzed by neuronal EAAT2 plays a role in glutamate metabolism, at least in the hippocampus. (3) Synapsin 1-Cre does not delete floxed genes in all neurons, and the contribution of neuronal EAAT2 is therefore likely to be larger than revealed in the present study.
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13
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Ottestad-Hansen S, Hu QX, Follin-Arbelet VV, Bentea E, Sato H, Massie A, Zhou Y, Danbolt NC. The cystine-glutamate exchanger (xCT, Slc7a11) is expressed in significant concentrations in a subpopulation of astrocytes in the mouse brain. Glia 2018; 66:951-970. [DOI: 10.1002/glia.23294] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 12/28/2017] [Accepted: 01/02/2018] [Indexed: 01/09/2023]
Affiliation(s)
- Sigrid Ottestad-Hansen
- The Neurotransporter Group, Section of Anatomy, Department of Molecular Medicine; Institute of Basic Medical Sciences, University of Oslo; Oslo 0317 Norway
| | - Qiu Xiang Hu
- The Neurotransporter Group, Section of Anatomy, Department of Molecular Medicine; Institute of Basic Medical Sciences, University of Oslo; Oslo 0317 Norway
| | - Virgine Veronique Follin-Arbelet
- The Neurotransporter Group, Section of Anatomy, Department of Molecular Medicine; Institute of Basic Medical Sciences, University of Oslo; Oslo 0317 Norway
| | - Eduard Bentea
- Department of Pharmaceutical Biotechnology and Molecular Biology; Center for Neurosciences, Vrije Universiteit Brussel; Brussels 1090 Belgium
| | - Hideyo Sato
- Laboratory of Biochemistry and Molecular Biology, Department of Medical Technology; Niigata University; Niigata Niigata Prefecture 950-2181 Japan
| | - Ann Massie
- Department of Pharmaceutical Biotechnology and Molecular Biology; Center for Neurosciences, Vrije Universiteit Brussel; Brussels 1090 Belgium
| | - Yun Zhou
- The Neurotransporter Group, Section of Anatomy, Department of Molecular Medicine; Institute of Basic Medical Sciences, University of Oslo; Oslo 0317 Norway
| | - Niels Christian Danbolt
- The Neurotransporter Group, Section of Anatomy, Department of Molecular Medicine; Institute of Basic Medical Sciences, University of Oslo; Oslo 0317 Norway
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14
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Drugs to Alter Extracellular Concentration of Glutamate: Modulators of Glutamate Uptake Systems. ACTA ACUST UNITED AC 2017. [DOI: 10.1007/978-1-4939-7228-9_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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15
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Danbolt NC, Zhou Y, Furness DN, Holmseth S. Strategies for immunohistochemical protein localization using antibodies: What did we learn from neurotransmitter transporters in glial cells and neurons. Glia 2016; 64:2045-2064. [PMID: 27458697 DOI: 10.1002/glia.23027] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 06/19/2016] [Accepted: 06/21/2016] [Indexed: 12/11/2022]
Abstract
Immunocytochemistry and Western blotting are still major methods for protein localization, but they rely on the specificity of the antibodies. Validation of antibody specificity remains challenging mostly because ideal negative controls are often unavailable. Further, immunochemical labeling patterns are also influenced by a number of other factors such as postmortem changes, fixation procedures and blocking agents as well as the general assay conditions (e.g., buffers, temperature, etc.). Western blotting similarly depends on tissue collection and sample preparation as well as the electrophoretic separation, transfer to blotting membranes and the immunochemical probing of immobilized molecules. Publication of inaccurate information on protein distribution has downstream consequences for other researchers because the interpretation of physiological and pharmacological observations depends on information on where ion channels, receptors, enzymes or transporters are located. Despite numerous reports, some of which are strongly worded, erroneous localization data are being published. Here we describe the extent of the problem and illustrate the nature of the pitfalls with examples from studies of neurotransmitter transporters. We explain the importance of supplementing immunochemical observations with other measurements (e.g., mRNA levels and distribution, protein activity, mass spectrometry, electrophysiological recordings, etc.) and why quantitative considerations are integral parts of the quality control. Further, we propose a practical strategy for researchers who plan to embark on a localization study. We also share our thoughts about guidelines for quality control. GLIA 2016;64:2045-2064.
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Affiliation(s)
- Niels Christian Danbolt
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
| | - Yun Zhou
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - David N Furness
- School of Life Sciences, Keele University, Keele, Staffs, United Kingdom
| | - Silvia Holmseth
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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16
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Danbolt NC, Furness DN, Zhou Y. Neuronal vs glial glutamate uptake: Resolving the conundrum. Neurochem Int 2016; 98:29-45. [PMID: 27235987 DOI: 10.1016/j.neuint.2016.05.009] [Citation(s) in RCA: 141] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 05/03/2016] [Accepted: 05/17/2016] [Indexed: 12/30/2022]
Abstract
Neither normal brain function nor the pathological processes involved in neurological diseases can be adequately understood without knowledge of the release, uptake and metabolism of glutamate. The reason for this is that glutamate (a) is the most abundant amino acid in the brain, (b) is at the cross-roads between several metabolic pathways, and (c) serves as the major excitatory neurotransmitter. In fact most brain cells express glutamate receptors and are thereby influenced by extracellular glutamate. In agreement, brain cells have powerful uptake systems that constantly remove glutamate from the extracellular fluid and thereby limit receptor activation. It has been clear since the 1970s that both astrocytes and neurons express glutamate transporters. However the relative contribution of neuronal and glial transporters to the total glutamate uptake activity, however, as well as their functional importance, has been hotly debated ever since. The present short review provides (a) an overview of what we know about neuronal glutamate uptake as well as an historical description of how we got there, and (b) a hypothesis reconciling apparently contradicting observations thereby possibly resolving the paradox.
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Affiliation(s)
- N C Danbolt
- The Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
| | - D N Furness
- School of Life Sciences, Keele University, Keele, Staffs. ST5 5BG, UK
| | - Y Zhou
- The Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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17
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Fontana ACK. Current approaches to enhance glutamate transporter function and expression. J Neurochem 2015; 134:982-1007. [DOI: 10.1111/jnc.13200] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Revised: 05/19/2015] [Accepted: 05/20/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Andréia C. K. Fontana
- Department of Pharmacology and Physiology; Drexel University College of Medicine; Philadelphia Pennsylvania USA
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18
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El Arfani A, Albertini G, Bentea E, Demuyser T, Van Eeckhaut A, Smolders I, Massie A. Alterations in the motor cortical and striatal glutamatergic system and D-serine levels in the bilateral 6-hydroxydopamine rat model for Parkinson's disease. Neurochem Int 2015; 88:88-96. [PMID: 26172319 DOI: 10.1016/j.neuint.2015.07.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 06/30/2015] [Accepted: 07/07/2015] [Indexed: 01/05/2023]
Abstract
Parkinson's disease (PD) is hallmarked by progressive degeneration of the substantia nigra pars compacta (SNc) neurons and is associated with aberrant glutamatergic activity. However, studies on the glutamatergic system in the motor cortex and striatum, two motor loop-related areas, are lacking in the clinically relevant bilateral SNc 6-hydroxydopamine (6-OHDA) rat model, and therefore led to the rationale behind the present investigations. Using Western blotting, the expression levels of the glial glutamate transporters, GLT-1 and GLAST, as well as xCT, the specific subunit of system xc(-), and the vesicular glutamate transporters, VGLUT1 and 2 were investigated at two different time points (1 week and 2 weeks) post-lesion. In addition, the total content of glutamate was measured. Moreover, the total D-serine levels were, to the best of our knowledge, studied for the first time in these two PD-related areas in the bilateral 6-OHDA rat model. In the motor cortex, no significant changes were observed in the different glutamate transporter expression levels in the bilaterally-lesioned rats. In the striatum, GLAST expression was significantly decreased at both time points whereas VGLUT1 and 2 expressions were significantly decreased 2 weeks after bilateral 6-OHDA lesion. Interestingly, bilateral 6-OHDA SNc lesion resulted in an enhancement of the total d-serine content in both motor cortex and striatum at 1 week post-lesion suggesting its possible involvement in the pathophysiology of PD. In conclusion, this study demonstrates disturbed glutamate and D-serine regulation in the bilateral SNc-lesioned brain which could contribute to the behavioral impairments in PD.
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Affiliation(s)
- Anissa El Arfani
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels, Belgium.
| | - Giulia Albertini
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels, Belgium.
| | - Eduard Bentea
- Department of Pharmaceutical Biotechnology and Molecular Biology, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels, Belgium.
| | - Thomas Demuyser
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels, Belgium.
| | - Ann Van Eeckhaut
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels, Belgium.
| | - Ilse Smolders
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels, Belgium.
| | - Ann Massie
- Department of Pharmaceutical Biotechnology and Molecular Biology, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels, Belgium.
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19
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Robel S, Buckingham SC, Boni JL, Campbell SL, Danbolt NC, Riedemann T, Sutor B, Sontheimer H. Reactive astrogliosis causes the development of spontaneous seizures. J Neurosci 2015; 35:3330-45. [PMID: 25716834 PMCID: PMC4339349 DOI: 10.1523/jneurosci.1574-14.2015] [Citation(s) in RCA: 189] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 12/16/2014] [Accepted: 01/12/2015] [Indexed: 11/21/2022] Open
Abstract
Epilepsy is one of the most common chronic neurologic diseases, yet approximately one-third of affected patients do not respond to anticonvulsive drugs that target neurons or neuronal circuits. Reactive astrocytes are commonly found in putative epileptic foci and have been hypothesized to be disease contributors because they lose essential homeostatic capabilities. However, since brain pathology induces astrocytes to become reactive, it is difficult to distinguish whether astrogliosis is a cause or a consequence of epileptogenesis. We now present a mouse model of genetically induced, widespread chronic astrogliosis after conditional deletion of β1-integrin (Itgβ1). In these mice, astrogliosis occurs in the absence of other pathologies and without BBB breach or significant inflammation. Electroencephalography with simultaneous video recording revealed that these mice develop spontaneous seizures during the first six postnatal weeks of life and brain slices show neuronal hyperexcitability. This was not observed in mice with neuronal-targeted β1-integrin deletion, supporting the hypothesis that astrogliosis is sufficient to induce epileptic seizures. Whole-cell patch-clamp recordings from astrocytes further suggest that the heightened excitability was associated with impaired astrocytic glutamate uptake. Moreover, the relative expression of the cation-chloride cotransporters (CCC) NKCC1 (Slc12a2) and KCC2 (Slc12a5), which are responsible for establishing the neuronal Cl(-) gradient that governs GABAergic inhibition were altered and the NKCC1 inhibitor bumetanide eliminated seizures in a subgroup of mice. These data suggest that a shift in the relative expression of neuronal NKCC1 and KCC2, similar to that observed in immature neurons during development, may contribute to astrogliosis-associated seizures.
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Affiliation(s)
- Stefanie Robel
- Department of Neurobiology, Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35209,
| | - Susan C Buckingham
- Department of Neurobiology, Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35209
| | - Jessica L Boni
- Department of Neurobiology, Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35209
| | - Susan L Campbell
- Department of Neurobiology, Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35209
| | - Niels C Danbolt
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway, and
| | - Therese Riedemann
- Institute of Physiology, Department of Physiological Genomics, Ludwig-Maximilians-University of Munich, 80336 Munich, Germany
| | - Bernd Sutor
- Institute of Physiology, Department of Physiological Genomics, Ludwig-Maximilians-University of Munich, 80336 Munich, Germany
| | - Harald Sontheimer
- Department of Neurobiology, Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35209
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20
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EAAT2 (GLT-1; slc1a2) glutamate transporters reconstituted in liposomes argues against heteroexchange being substantially faster than net uptake. J Neurosci 2015; 34:13472-85. [PMID: 25274824 DOI: 10.1523/jneurosci.2282-14.2014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The EAAT2 glutamate transporter, accounts for >90% of hippocampal glutamate uptake. Although EAAT2 is predominantly expressed in astrocytes, ∼10% of EAAT2 molecules are found in axon terminals. Despite the lower level of EAAT2 expression in glutamatergic terminals, when hippocampal slices are incubated with low concentration of d-aspartate (an EAAT2 substrate), axon terminals accumulate d-aspartate as quickly as astroglia. This implies an unexplained mismatch between the distribution of EAAT2 protein and of EAAT2-mediated transport activity. One hypothesis is that (1) heteroexchange of internal substrate with external substrate is considerably faster than net uptake and (2) terminals favor heteroexchange because of high levels of internal glutamate. However, it is currently unknown whether heteroexchange and uptake have similar or different rates. To address this issue, we used a reconstituted system to compare the relative rates of the two processes in rat and mice. Net uptake was sensitive to changes in the membrane potential and was stimulated by external permeable anions in agreement with the existence of an uncoupled anion conductance. By using the latter, we also demonstrate that the rate of heteroexchange also depends on the membrane potential. Additionally, our data further suggest the presence of a sodium leak in EAAT2. By incorporating the new findings in our previous model of glutamate uptake by EAAT2, we predict that the voltage sensitivity of exchange is caused by the voltage-dependent third Na(+) binding. Further, both our experiments and simulations suggest that the relative rates of net uptake and heteroexchange are comparable in EAAT2.
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21
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Roberts RC, Roche JK, McCullumsmith RE. Localization of excitatory amino acid transporters EAAT1 and EAAT2 in human postmortem cortex: a light and electron microscopic study. Neuroscience 2014; 277:522-40. [PMID: 25064059 PMCID: PMC4164610 DOI: 10.1016/j.neuroscience.2014.07.019] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 07/14/2014] [Indexed: 01/03/2023]
Abstract
The process of glutamate release, activity, and reuptake involves the astrocyte, the presynaptic and postsynaptic neurons. Glutamate is released into the synapse and may occupy and activate receptors on both neurons and astrocytes. Glutamate is rapidly removed from the synapse by a family of plasma membrane excitatory amino acid transporters (EAATs), also localized to neurons and astrocytes. The purpose of the present study was to examine EAAT labeling in the postmortem human cortex at the light and electron microscopic (EM) levels. The postmortem prefrontal cortex was processed for EAAT1 and EAAT2 immunohistochemistry. At the light microscopic level, EAAT1 and EAAT2 labeling was found in both gray and white matter. Most cellular labeling was in small cells which were morphologically similar to glia. In addition, EAAT1-labeled neurons were scattered throughout, some of which were pyramidal in shape. At the EM level, EAAT1 and EAAT2 labeling was found in astrocytic soma and processes surrounding capillaries. EAAT labeling was also found in small astrocytic processes adjacent to axon terminals forming asymmetric (glutamatergic) synapses. While EAAT2 labeling was most prevalent in astrocytic processes, EAAT1 labeling was also present in neuronal processes including the soma, axons, and dendritic spines. Expression of EAAT1 protein on neurons may be due to the hypoxia associated with the postmortem interval, and requires further confirmation. The localization of EAATs on the astrocytic plasma membrane and adjacent to excitatory synapses is consistent with the function of facilitating glutamate reuptake and limiting glutamate spillover. Establishment that EAAT1 and EAAT2 can be measured at the EM level in human postmortem tissues will permit testing of hypotheses related to these molecules in diseases lacking analogous animal models.
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Affiliation(s)
- R C Roberts
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA.
| | - J K Roche
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - R E McCullumsmith
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
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22
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Zhou Y, Danbolt NC. Glutamate as a neurotransmitter in the healthy brain. J Neural Transm (Vienna) 2014; 121:799-817. [PMID: 24578174 PMCID: PMC4133642 DOI: 10.1007/s00702-014-1180-8] [Citation(s) in RCA: 514] [Impact Index Per Article: 51.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 02/11/2014] [Indexed: 12/13/2022]
Abstract
Glutamate is the most abundant free amino acid in the brain and is at the crossroad between multiple metabolic pathways. Considering this, it was a surprise to discover that glutamate has excitatory effects on nerve cells, and that it can excite cells to their death in a process now referred to as "excitotoxicity". This effect is due to glutamate receptors present on the surface of brain cells. Powerful uptake systems (glutamate transporters) prevent excessive activation of these receptors by continuously removing glutamate from the extracellular fluid in the brain. Further, the blood-brain barrier shields the brain from glutamate in the blood. The highest concentrations of glutamate are found in synaptic vesicles in nerve terminals from where it can be released by exocytosis. In fact, glutamate is the major excitatory neurotransmitter in the mammalian central nervous system. It took, however, a long time to realize that. The present review provides a brief historical description, gives a short overview of glutamate as a transmitter in the healthy brain, and comments on the so-called glutamate-glutamine cycle. The glutamate transporters responsible for the glutamate removal are described in some detail.
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Affiliation(s)
- Y. Zhou
- The Neurotransporter Group, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Blindern, P.O. Box 1105, 0317 Oslo, Norway
| | - N. C. Danbolt
- The Neurotransporter Group, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Blindern, P.O. Box 1105, 0317 Oslo, Norway
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23
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Abstract
L-Glutamate is the predominant excitatory neurotransmitter in the mammalian central nervous system and plays important roles in a wide variety of brain functions, but it is also a key player in the pathogenesis of many neurological disorders. The control of glutamate concentrations is critical to the normal functioning of the central nervous system, and in this review we discuss how glutamate transporters regulate glutamate concentrations to maintain dynamic signaling mechanisms between neurons. In 2004, the crystal structure of a prokaryotic homolog of the mammalian glutamate transporter family of proteins was crystallized and its structure determined. This has paved the way for a better understanding of the structural basis for glutamate transporter function. In this review we provide a broad perspective of this field of research, but focus primarily on the more recent studies with a particular emphasis on how our understanding of the structure of glutamate transporters has generated new insights.
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24
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Zhou Y, Waanders LF, Holmseth S, Guo C, Berger UV, Li Y, Lehre AC, Lehre KP, Danbolt NC. Proteome analysis and conditional deletion of the EAAT2 glutamate transporter provide evidence against a role of EAAT2 in pancreatic insulin secretion in mice. J Biol Chem 2013; 289:1329-44. [PMID: 24280215 DOI: 10.1074/jbc.m113.529065] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Islet function is incompletely understood in part because key steps in glutamate handling remain undetermined. The glutamate (excitatory amino acid) transporter 2 (EAAT2; Slc1a2) has been hypothesized to (a) provide islet cells with glutamate, (b) protect islet cells against high extracellular glutamate concentrations, (c) mediate glutamate release, or (d) control the pH inside insulin secretory granules. Here we floxed the EAAT2 gene to produce the first conditional EAAT2 knock-out mice. Crossing with Nestin-cyclization recombinase (Cre) eliminated EAAT2 from the brain, resulting in epilepsy and premature death, confirming the importance of EAAT2 for brain function and validating the genetic construction. Crossing with insulin-Cre lines (RIP-Cre and IPF1-Cre) to obtain pancreas-selective deletion did not appear to affect survival, growth, glucose tolerance, or β-cell number. We found (using TaqMan RT-PCR, immunoblotting, immunocytochemistry, and proteome analysis) that the EAAT2 levels were too low to support any of the four hypothesized functions. The proteome analysis detected more than 7,000 islet proteins of which more than 100 were transporters. Although mitochondrial glutamate transporters and transporters for neutral amino acids were present at high levels, all other transporters with known ability to transport glutamate were strikingly absent. Glutamate-metabolizing enzymes were abundant. The level of glutamine synthetase was 2 orders of magnitude higher than that of glutaminase. Taken together this suggests that the uptake of glutamate by islets from the extracellular fluid is insignificant and that glutamate is intracellularly produced. Glutamine synthetase may be more important for islets than assumed previously.
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Affiliation(s)
- Yun Zhou
- From The Neurotransporter Group, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway
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Feresten AH, Barakauskas V, Ypsilanti A, Barr AM, Beasley CL. Increased expression of glial fibrillary acidic protein in prefrontal cortex in psychotic illness. Schizophr Res 2013; 150:252-7. [PMID: 23911257 DOI: 10.1016/j.schres.2013.07.024] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 07/05/2013] [Accepted: 07/11/2013] [Indexed: 11/16/2022]
Abstract
Astrocyte dysregulation has been implicated in the pathophysiology of schizophrenia (SCZ) and bipolar disorder (BPD), however the exact nature of astrocytic alterations remains to be identified. In this study we investigated whether levels of four astrocyte-specific proteins; glial fibrillary acidic protein (GFAP), aldehyde dehydrogenase 1L1 (ALDH1L1), vimentin and excitatory amino acid transporter 1 (EAAT1) are altered in SCZ and BPD. Relative concentrations of GFAP, ALDH1L1, vimentin and EAAT1 were assessed post-mortem in dorsolateral prefrontal cortex in SCZ (n=35), BPD (n=34) and non-psychiatric controls (n=35) by western blotting. The same proteins were also quantified in cingulate cortex of rats administered the antipsychotics haloperidol and clozapine. Elevated levels of GFAP were observed in SCZ and BPD, when compared to controls. GFAP was also significantly increased when comparing individuals with psychotic symptoms against those without. Vimentin, ALDH1L1 and EAAT1 levels did not differ between groups. Rats exposed to antipsychotics did not exhibit significant differences in any astrocytic protein, suggesting that increased GFAP in SCZ is not attributable to antipsychotic treatment. Our findings indicate that astrocyte pathology may be associated with psychotic symptoms. Lack of ALDH1L1 and vimentin variability and increased GFAP levels may imply that astrocyte numbers are unchanged but astrocytes are partially activated, or may indicate a specific dysregulation of GFAP.
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Affiliation(s)
- Abigail H Feresten
- Department of Psychiatry, University of British Columbia, Vancouver, Canada
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Abstract
The mammalian genome contains four genes encoding GABA transporters (GAT1, slc6a1; GAT2, slc6a13; GAT3, slc6a11; BGT1, slc6a12) and five glutamate transporter genes (EAAT1, slc1a3; EAAT2, slc1a2; EAAT3, slc1a1; EAAT4, slc1a6; EAAT5, slc1a7). These transporters keep the extracellular levels of GABA and excitatory amino acids low and provide amino acids for metabolic purposes. The various transporters have different properties both with respect to their transport functions and with respect to their ability to act as ion channels. Further, they are differentially regulated. To understand the physiological roles of the individual transporter subtypes, it is necessary to obtain information on their distributions and expression levels. Quantitative data are important as the functional capacity is limited by the number of transporter molecules. The most important and most abundant transporters for removal of transmitter glutamate in the brain are EAAT2 (GLT-1) and EAAT1 (GLAST), while GAT1 and GAT3 are the major GABA transporters in the brain. EAAT3 (EAAC1) does not appear to play a role in signal transduction, but plays other roles. Due to their high uncoupled anion conductance, EAAT4 and EAAT5 seem to be acting more like inhibitory glutamate receptors than as glutamate transporters. GAT2 and BGT1 are primarily expressed in the liver and kidney, but are also found in the leptomeninges, while the levels in brain tissue proper are too low to have any impact on GABA removal, at least in normal young adult mice. The present review will provide summary of what is currently known and will also discuss some methodological pitfalls.
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Affiliation(s)
- Yun Zhou
- The Neurotransporter Group, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Niels Christian Danbolt
- The Neurotransporter Group, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- *Correspondence: Niels Christian Danbolt, The Neurotransporter Group, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1105 Blindern, Oslo N-0317, Norway e-mail:
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Zhou Y, Holmseth S, Guo C, Hassel B, Höfner G, Huitfeldt HS, Wanner KT, Danbolt NC. Deletion of the γ-aminobutyric acid transporter 2 (GAT2 and SLC6A13) gene in mice leads to changes in liver and brain taurine contents. J Biol Chem 2012; 287:35733-35746. [PMID: 22896705 DOI: 10.1074/jbc.m112.368175] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The GABA transporters (GAT1, GAT2, GAT3, and BGT1) have mostly been discussed in relation to their potential roles in controlling the action of transmitter GABA in the nervous system. We have generated the first mice lacking the GAT2 (slc6a13) gene. Deletion of GAT2 (both mRNA and protein) neither affected growth, fertility, nor life span under nonchallenging rearing conditions. Immunocytochemistry showed that the GAT2 protein was predominantly expressed in the plasma membranes of periportal hepatocytes and in the basolateral membranes of proximal tubules in the renal cortex. This was validated by processing tissue from wild-type and knockout mice in parallel. Deletion of GAT2 reduced liver taurine levels by 50%, without affecting the expression of the taurine transporter TAUT. These results suggest an important role for GAT2 in taurine uptake from portal blood into liver. In support of this notion, GAT2-transfected HEK293 cells transported [(3)H]taurine. Furthermore, most of the uptake of [(3)H]GABA by cultured rat hepatocytes was due to GAT2, and this uptake was inhibited by taurine. GAT2 was not detected in brain parenchyma proper, excluding a role in GABA inactivation. It was, however, expressed in the leptomeninges and in a subpopulation of brain blood vessels. Deletion of GAT2 increased brain taurine levels by 20%, suggesting a taurine-exporting role for GAT2 in the brain.
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Affiliation(s)
- Yun Zhou
- Centre of Molecular Biology and Neuroscience, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, N-0317 Oslo, Norway
| | - Silvia Holmseth
- Centre of Molecular Biology and Neuroscience, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, N-0317 Oslo, Norway
| | - Caiying Guo
- HHMI, Janelia Farm Research Campus, Ashburn, Virginia 20147
| | - Bjørnar Hassel
- Department for Neurohabilitation, Oslo University Hospital, N-0372 Oslo, Norway; Norwegian Defense Research Establishment, N-2027 Kjeller, Norway
| | - Georg Höfner
- Department für Pharmazie, Zentrum für Pharmaforschung, Ludwig-Maximilians-Universität München, D-81377 München, Germany
| | - Henrik S Huitfeldt
- Department of Pathology, Oslo University Hospital, University of Oslo, N-0372 Oslo, Norway
| | - Klaus T Wanner
- Department für Pharmazie, Zentrum für Pharmaforschung, Ludwig-Maximilians-Universität München, D-81377 München, Germany
| | - Niels C Danbolt
- Centre of Molecular Biology and Neuroscience, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, N-0317 Oslo, Norway.
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