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Alijanpour S, Miryounesi M, Ghafouri-Fard S. The role of excitatory amino acid transporter 2 (EAAT2) in epilepsy and other neurological disorders. Metab Brain Dis 2023; 38:1-16. [PMID: 36173507 DOI: 10.1007/s11011-022-01091-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 09/15/2022] [Indexed: 02/03/2023]
Abstract
Glutamate is the major excitatory neurotransmitter in the central nervous system (CNS). Excitatory amino acid transporters (EAATs) have important roles in the uptake of glutamate and termination of glutamatergic transmission. Up to now, five EAAT isoforms (EAAT1-5) have been identified in mammals. The main focus of this review is EAAT2. This protein has an important role in the pathoetiology of epilepsy. De novo dominant mutations, as well as inherited recessive mutation in this gene, have been associated with epilepsy. Moreover, dysregulation of this protein is implicated in a range of neurological diseases, namely amyotrophic lateral sclerosis, alzheimer's disease, parkinson's disease, schizophrenia, epilepsy, and autism. In this review, we summarize the role of EAAT2 in epilepsy and other neurological disorders, then provide an overview of the therapeutic modulation of this protein.
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Affiliation(s)
- Sahar Alijanpour
- Department of Medical Genetics, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Miryounesi
- Department of Medical Genetics, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Soudeh Ghafouri-Fard
- Department of Medical Genetics, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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2
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Nozohouri S, Zhang Y, Albekairi TH, Vaidya B, Abbruscato TJ. Glutamate Buffering Capacity and Blood-Brain Barrier Protection of Opioid Receptor Agonists Biphalin and Nociceptin. J Pharmacol Exp Ther 2021; 379:260-269. [PMID: 34663677 DOI: 10.1124/jpet.121.000831] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 09/29/2021] [Indexed: 12/23/2022] Open
Abstract
Opioids play crucial roles in the regulation of many important brain functions including pain, memory, and neurogenesis. Activation of opioid receptors is reported to have neuroprotective effects after ischemic reperfusion injury. The objective of this study was to understand the role of biphalin and nociceptin, opioid receptor agonists, on blood-brain barrier (BBB) integrity during ischemic stroke. In this study, we aimed to measure the effect of biphalin and nociceptin on astrocytic glutamate uptake and on expression of excitatory amino acid transporter to study the indirect role of astrocytes on opioid receptor-mediated BBB protection during in vitro stroke conditions. We used mouse brain endothelial cells (bEnd.3) and primary astrocytes as an in vitro BBB model. Restrictive BBB properties were evaluated by measuring [14C] sucrose paracellular permeability and the redistribution of the tight junction proteins. The protective effect of biphalin and nociceptin on BBB integrity was assessed after exposing cells to oxygen glucose deprivation (OGD) and glutamate. It was observed that combined stress (2 mM glutamate and 2 hours of OGD) significantly reduced glutamate uptake by astrocytes; however, biphalin and nociceptin treatment increased glutamate uptake in primary astrocytes. This suggests a role of increased astrocytic buffering capacity in opioid-meditated protection of the BBB during ischemic stroke. It was also found that the combined stress significantly increased [14C] sucrose paracellular permeability in an in vitro BBB model. Biphalin and nociceptin treatment attenuated the effect of the combined stress, which was reversed by the opioid receptor antagonists, suggesting the role of opioid receptors in biphalin and nociception's BBB modulatory activity. SIGNIFICANT STATEMENT: There is an unmet need for discovering new efficacious therapeutic agents to offset the deleterious effects of ischemic stroke. Given the confirmed roles of opioid receptors in the regulation of central nervous system functions, opioid receptor agonists have been studied as potential neuroprotective options in ischemic conditions. This study adds to the knowledge about the cerebrovascular protective effects of opioid receptor agonists and provides insight about the mechanism of action of these agents.
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Affiliation(s)
- Saeideh Nozohouri
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas (S.N., Y.Z., T.H.A., B.V., T.J.A.); and Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia (T.H.A.)
| | - Yong Zhang
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas (S.N., Y.Z., T.H.A., B.V., T.J.A.); and Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia (T.H.A.)
| | - Thamer H Albekairi
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas (S.N., Y.Z., T.H.A., B.V., T.J.A.); and Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia (T.H.A.)
| | - Bhuvaneshwar Vaidya
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas (S.N., Y.Z., T.H.A., B.V., T.J.A.); and Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia (T.H.A.)
| | - Thomas J Abbruscato
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas (S.N., Y.Z., T.H.A., B.V., T.J.A.); and Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia (T.H.A.)
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3
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Sears SM, Hewett SJ. Influence of glutamate and GABA transport on brain excitatory/inhibitory balance. Exp Biol Med (Maywood) 2021; 246:1069-1083. [PMID: 33554649 DOI: 10.1177/1535370221989263] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
An optimally functional brain requires both excitatory and inhibitory inputs that are regulated and balanced. A perturbation in the excitatory/inhibitory balance-as is the case in some neurological disorders/diseases (e.g. traumatic brain injury Alzheimer's disease, stroke, epilepsy and substance abuse) and disorders of development (e.g. schizophrenia, Rhett syndrome and autism spectrum disorder)-leads to dysfunctional signaling, which can result in impaired cognitive and motor function, if not frank neuronal injury. At the cellular level, transmission of glutamate and GABA, the principle excitatory and inhibitory neurotransmitters in the central nervous system control excitatory/inhibitory balance. Herein, we review the synthesis, release, and signaling of GABA and glutamate followed by a focused discussion on the importance of their transport systems to the maintenance of excitatory/inhibitory balance.
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Affiliation(s)
- Sheila Ms Sears
- Department of Biology, Program in Neuroscience, 2029Syracuse University, Syracuse, NY 13244, USA
| | - Sandra J Hewett
- Department of Biology, Program in Neuroscience, 2029Syracuse University, Syracuse, NY 13244, USA
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4
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Pajarillo E, Rizor A, Lee J, Aschner M, Lee E. The role of astrocytic glutamate transporters GLT-1 and GLAST in neurological disorders: Potential targets for neurotherapeutics. Neuropharmacology 2019; 161:107559. [PMID: 30851309 PMCID: PMC6731169 DOI: 10.1016/j.neuropharm.2019.03.002] [Citation(s) in RCA: 190] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 02/28/2019] [Accepted: 03/02/2019] [Indexed: 12/12/2022]
Abstract
Glutamate is the primary excitatory neurotransmitter in the central nervous system (CNS) which initiates rapid signal transmission in the synapse before its re-uptake into the surrounding glia, specifically astrocytes. The astrocytic glutamate transporters glutamate-aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1) and their human homologs excitatory amino acid transporter 1 (EAAT1) and 2 (EAAT2), respectively, are the major transporters which take up synaptic glutamate to maintain optimal extracellular glutamic levels, thus preventing accumulation in the synaptic cleft and ensuing excitotoxicity. Growing evidence has shown that excitotoxicity is associated with various neurological disorders, including amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), Parkinson's disease (PD), manganism, ischemia, schizophrenia, epilepsy, and autism. While the mechanisms of neurological disorders are not well understood, the dysregulation of GLAST/GLT-1 may play a significant role in excitotoxicity and associated neuropathogenesis. The expression and function of GLAST/GLT-1 may be dysregulated at the genetic, epigenetic, transcriptional or translational levels, leading to high levels of extracellular glutamate and excitotoxicity. Consequently, understanding the regulatory mechanisms of GLAST/GLT-1 has been an area of interest in developing therapeutics for the treatment of neurological disorders. Pharmacological agents including β-lactam antibiotics, estrogen/selective estrogen receptor modulators (SERMs), growth factors, histone deacetylase inhibitors (HDACi), and translational activators have shown significant efficacy in enhancing the expression and function of GLAST/GLT-1 and glutamate uptake both in vitro and in vivo. This comprehensive review will discuss the regulatory mechanisms of GLAST/GLT-1, their association with neurological disorders, and the pharmacological agents which mediate their expression and function. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Affiliation(s)
- Edward Pajarillo
- Department of Pharmaceutical Sciences, College of Pharmacy, Florida A&M University, Tallahassee, FL, 32301, USA
| | - Asha Rizor
- Department of Pharmaceutical Sciences, College of Pharmacy, Florida A&M University, Tallahassee, FL, 32301, USA
| | - Jayden Lee
- Department of Speech, Language & Hearing Sciences, Boston University, Boston, MA, 02215, USA
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Eunsook Lee
- Department of Pharmaceutical Sciences, College of Pharmacy, Florida A&M University, Tallahassee, FL, 32301, USA.
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5
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Yshii L, Pignolet B, Mauré E, Pierau M, Brunner-Weinzierl M, Hartley O, Bauer J, Liblau R. IFN-γ is a therapeutic target in paraneoplastic cerebellar degeneration. JCI Insight 2019; 4:127001. [PMID: 30944244 DOI: 10.1172/jci.insight.127001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 02/21/2019] [Indexed: 12/18/2022] Open
Abstract
Paraneoplastic neurological disorders result from an autoimmune response against neural self-antigens that are ectopically expressed in neoplastic cells. In paraneoplastic disorders associated to autoantibodies against intracellular proteins, such as paraneoplastic cerebellar degeneration (PCD), current data point to a major role of cell-mediated immunity. In an animal model, in which a neo-self-antigen was expressed in both Purkinje neurons and implanted breast tumor cells, immune checkpoint blockade led to complete tumor control at the expense of cerebellum infiltration by T cells and Purkinje neuron loss, thereby mimicking PCD. Here, we identify 2 potential therapeutic targets expressed by cerebellum-infiltrating T cells in this model, namely α4 integrin and IFN-γ. Mice with PCD were treated with anti-α4 integrin antibodies or neutralizing anti-IFN-γ antibodies at the onset of neurological signs. Although blocking α4 integrin had little or no impact on disease development, treatment using the anti-IFN-γ antibody led to almost complete protection from PCD. These findings strongly suggest that the production of IFN-γ by cerebellum-invading T cells plays a major role in Purkinje neuron death. Our successful preclinical use of neutralizing anti-IFN-γ antibody for the treatment of PCD offers a potentially new therapeutic opportunity for cancer patients at the onset of paraneoplastic neurological disorders.
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Affiliation(s)
- Lidia Yshii
- Centre de Physiopathologie Toulouse-Purpan (CPTP), Université de Toulouse, CNRS, Inserm, UPS, Toulouse, France
| | - Béatrice Pignolet
- Centre de Physiopathologie Toulouse-Purpan (CPTP), Université de Toulouse, CNRS, Inserm, UPS, Toulouse, France.,Department of Clinical Neurosciences, Toulouse University Hospital, Toulouse, France
| | - Emilie Mauré
- Centre de Physiopathologie Toulouse-Purpan (CPTP), Université de Toulouse, CNRS, Inserm, UPS, Toulouse, France
| | - Mandy Pierau
- Department of Experimental Pediatrics, University Hospital, Otto-von-Guericke University, Magdeburg, Germany
| | - Monika Brunner-Weinzierl
- Department of Experimental Pediatrics, University Hospital, Otto-von-Guericke University, Magdeburg, Germany
| | - Oliver Hartley
- Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Jan Bauer
- Department of Neuroimmunology, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Roland Liblau
- Centre de Physiopathologie Toulouse-Purpan (CPTP), Université de Toulouse, CNRS, Inserm, UPS, Toulouse, France
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Perkins EM, Clarkson YL, Suminaite D, Lyndon AR, Tanaka K, Rothstein JD, Skehel PA, Wyllie DJA, Jackson M. Loss of cerebellar glutamate transporters EAAT4 and GLAST differentially affects the spontaneous firing pattern and survival of Purkinje cells. Hum Mol Genet 2018; 27:2614-2627. [PMID: 29741614 PMCID: PMC6049029 DOI: 10.1093/hmg/ddy169] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 04/30/2018] [Accepted: 05/01/2018] [Indexed: 12/20/2022] Open
Abstract
Loss of excitatory amino acid transporters (EAATs) has been implicated in a number of human diseases including spinocerebellar ataxias, Alzhiemer's disease and motor neuron disease. EAAT4 and GLAST/EAAT1 are the two predominant EAATs responsible for maintaining low extracellular glutamate levels and preventing neurotoxicity in the cerebellum, the brain region essential for motor control. Here using genetically modified mice we identify new critical roles for EAAT4 and GLAST/EAAT1 as modulators of Purkinje cell (PC) spontaneous firing patterns. We show high EAAT4 levels, by limiting mGluR1 signalling, are essential in constraining inherently heterogeneous firing of zebrin-positive PCs. Moreover mGluR1 antagonists were found to restore regular spontaneous PC activity and motor behaviour in EAAT4 knockout mice. In contrast, GLAST/EAAT1 expression is required to sustain normal spontaneous simple spike activity in low EAAT4 expressing (zebrin-negative) PCs by restricting NMDA receptor activation. Blockade of NMDA receptor activity restores spontaneous activity in zebrin-negative PCs of GLAST knockout mice and furthermore alleviates motor deficits. In addition both transporters have differential effects on PC survival, with zebrin-negative PCs more vulnerable to loss of GLAST/EAAT1 and zebrin-positive PCs more vulnerable to loss of EAAT4. These findings reveal that glutamate transporter dysfunction through elevated extracellular glutamate and the aberrant activation of extrasynaptic receptors can disrupt cerebellar output by altering spontaneous PC firing. This expands our understanding of disease mechanisms in cerebellar ataxias and establishes EAATs as targets for restoring homeostasis in a variety of neurological diseases where altered cerebellar output is now thought to play a key role in pathogenesis.
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Affiliation(s)
- Emma M Perkins
- The Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
| | - Yvonne L Clarkson
- The Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
| | - Daumante Suminaite
- The Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
| | - Alastair R Lyndon
- School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, John Muir Building, Riccarton, Edinburgh, UK
| | - Kohichi Tanaka
- Laboratory of Molecular Neuroscience, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-Ku, Tokyo, Japan
| | - Jeffrey D Rothstein
- Department of Neurology and Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Paul A Skehel
- The Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
| | - David J A Wyllie
- The Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
- Centre for Brain Development and Repair, Institute for Stem Cell Biology and Regenerative Medicine, Bangalore, India
| | - Mandy Jackson
- The Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
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PKC and CaMK-II inhibitions coordinately rescue ischemia-induced GABAergic neuron dysfunction. Oncotarget 2018; 8:39309-39322. [PMID: 28445148 PMCID: PMC5503615 DOI: 10.18632/oncotarget.16947] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 03/15/2017] [Indexed: 01/01/2023] Open
Abstract
Cerebral ischemia leads to neuronal death for stroke, in which the imbalance between glutamatergic neurons and GABAergic neurons toward neural excitotoxicity is presumably involved. GABAergic neurons are vulnerable to pathological factors and impaired in an early stage of ischemia. The rescue of GABAergic neurons is expected to be the strategy to reserve ischemic neuronal impairment. As protein kinase C (PKC) and calmodulin-dependent protein kinase II (CaMK-II) are activated during ischemia, we have investigated whether the inhibitions of these kinases rescue the ischemic impairment of cortical GABAergic neurons. The functions of GABAergic neurons were analyzed by whole-cell recording in the cortical slices during ischemia and in presence of 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (CaMK-II inhibitor) and chelerythrine chloride (PKC inhibitor). Our results indicate that PKC inhibitor or CaMK-II inhibitor partially prevents ischemia-induced functional deficits of cortical GABAergic neurons. Moreover, the combination of PKC and CaMK-II inhibitors synergistically reverses this ischemia-induced deficit of GABAergic neurons. One of potential therapeutic strategies for ischemic stroke may be to rescue the ischemia-induced deficit of cortical GABAergic neurons by inhibiting PKC and CaMK-II.
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Focal Ischaemic Infarcts Expand Faster in Cerebellar Cortex than Cerebral Cortex in a Mouse Photothrombotic Stroke Model. Transl Stroke Res 2018; 9:643-653. [PMID: 29455391 DOI: 10.1007/s12975-018-0615-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 02/02/2018] [Accepted: 02/04/2018] [Indexed: 12/31/2022]
Abstract
It is generally accepted that the cerebellum is particularly vulnerable to ischaemic injury, and this may contribute to the high mortality arising from posterior circulation strokes. However, this has not been systematically examined in an animal model. This study compared the development and resolution of matched photothrombotic microvascular infarcts in the cerebellar and cerebral cortices in adult 129/SvEv mice of both sexes. The photothrombotic lesions were made using tail vein injection of Rose Bengal with a 532 nm laser projected onto a 2 mm diameter aperture over the target region of the brain (with skull thinning). Infarct size was then imaged histologically following 2 h to 30-day survival using serial reconstruction of haematoxylin and eosin stained cryosections. This was complemented with immunohistochemistry for neuron and glial markers. At 2 h post-injury, the cerebellar infarct volume averaged ~ 2.7 times that of the cerebral cortex infarcts. Infarct volume reached maximum in the cerebellum in a quarter of the time (24 h) taken in the cerebral cortex (4 days). Remodelling resolved the infarcts within a month, leaving significantly larger residual injury volume in the cerebellum. The death of neurons in the core lesion at 2 h was confirmed by NeuN and Calbindin immunofluorescence, alongside activation of astrocytes and microglia. The latter persisted in the region within and surrounding the residual infarct at 30 days. This comparison of acute focal ischaemic injuries in cerebellar and cerebral cortices provides direct confirmation of exacerbation of neuropathology and faster kinetics in the cerebellum.
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Liu Z, Huang Y, Liu L, Zhang L. Inhibitions of PKC and CaMK-II synergistically rescue ischemia-induced astrocytic dysfunction. Neurosci Lett 2017; 657:199-203. [DOI: 10.1016/j.neulet.2017.08.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 08/02/2017] [Accepted: 08/07/2017] [Indexed: 01/29/2023]
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10
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Ritter AC, Kammerer CM, Brooks MM, Conley YP, Wagner AK. Genetic variation in neuronal glutamate transport genes and associations with posttraumatic seizure. Epilepsia 2016; 57:984-93. [PMID: 27153812 PMCID: PMC4903934 DOI: 10.1111/epi.13397] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2016] [Indexed: 12/18/2022]
Abstract
OBJECTIVE Posttraumatic seizures (PTS) commonly occur following severe traumatic brain injury (sTBI). Risk factors for PTS have been identified, but variability in who develops PTS remains. Excitotoxicity may influence epileptogenesis following sTBI. Glutamate transporters manage glutamate levels and excitatory neurotransmission, and they have been associated with both epilepsy and TBI. Therefore, we aimed to determine if genetic variation in neuronal glutamate transporter genes is associated with accelerated epileptogenesis and increased PTS risk after sTBI. METHODS Individuals (N = 253) 18-75 years of age with sTBI were assessed for genetic relationships with PTS. Single nucleotide polymorphisms (SNPs) within SLC1A1 and SLC1A6 were assayed. Kaplan-Meier estimates and log-rank statistics were used to compare seizure rates from injury to 3 years postinjury for SNPs by genotype. Hazard ratios (HRs) were estimated using Cox proportional hazards regression for SNPs significant in Kaplan-Meier analyses adjusting for known PTS risk factors. RESULTS Thirty-two tagging SNPs were examined (SLC1A1: n = 28, SLC1A6: n = 4). Forty-nine subjects (19.37%) had PTS. Of these, 18 (36.7%) seized within 7 days, and 31 (63.3%) seized between 8 days and 3 years post-TBI. With correction for multiple comparisons, genotypes at SNP rs10974620 (SLC1A1) were significantly associated with time to first seizure across the full 3-year follow-up (seizure rates: 77.1% minor allele homozygotes, 24.8% heterozygotes, 16.6% major allele homozygotes; p = 0.001). When seizure follow-up began day 2 postinjury, genotypes at SNP rs7858819 (SLC1A1) were significantly associated with PTS risk (seizure rates: 52.7% minor allele homozygotes, 11.8% heterozygotes, 21.1% major allele homozygotes; p = 0.002). After adjusting for covariates, we found that rs10974620 remained significant (p = 0.017, minor allele versus major allele homozygotes HR 3.4, 95% confidence interval [CI] 1.3-9.3). rs7858819 also remained significant in adjusted models (p = 0.023, minor allele versus major allele homozygotes HR 3.4, 95%CI 1.1-10.5). SIGNIFICANCE Variations within SLC1A1 are associated with risk of epileptogenesis following sTBI. Future studies need to confirm findings, but variation within neuronal glutamate transporter genes may represent a possible pharmaceutical target for PTS prevention and treatment.
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Affiliation(s)
- Anne C Ritter
- Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA
| | | | - Maria M Brooks
- Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA
| | - Yvette P Conley
- Department of Health Promotion and Human Genetics, University of Pittsburgh, Pittsburgh, PA
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA
| | - Amy K Wagner
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA
- Center for Neuroscience at University of Pittsburgh, Pittsburgh, PA
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Chrobak AA, Soltys Z. Bergmann Glia, Long-Term Depression, and Autism Spectrum Disorder. Mol Neurobiol 2016; 54:1156-1166. [PMID: 26809583 PMCID: PMC5310553 DOI: 10.1007/s12035-016-9719-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 01/12/2016] [Indexed: 12/22/2022]
Abstract
Bergmann glia (BG), a specific type of radial astrocytes in the cerebellum, play a variety of vital functions in the development of this structure. However, the possible role of BG in the development of abnormalities observed in individuals with autism spectrum disorder (ASD) seems to be underestimated. One of the most consistent findings observed in ASD patients is loss of Purkinje cells (PCs). Such a defect may be caused by dysregulation of glutamate homeostasis, which is maintained mainly by BG. Moreover, these glial cells are involved in long-term depression (LTD), a form of plasticity which can additionally subserve neuroprotective functions. The aim of presented review is to summarize the current knowledge about interactions which occur between PC and BG, with special emphasis on those which are relevant to the survival and proper functioning of cerebellar neurons.
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Affiliation(s)
- Adrian Andrzej Chrobak
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, Gronostajowa St. 9, Cracow, 30-387, Poland. .,Faculty of Medicine, Jagiellonian University Medical College, Kopernika St. 21A, Cracow, 31-501, Poland.
| | - Zbigniew Soltys
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, Gronostajowa St. 9, Cracow, 30-387, Poland
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12
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Takayasu Y, Shino M, Nikkuni O, Yoshida Y, Furuya N, Chikamatsu K. Oxygen-glucose deprivation increases firing of unipolar brush cells and enhances spontaneous EPSCs in Purkinje cells in the vestibulo-cerebellum. Neurosci Res 2015; 106:1-11. [PMID: 26535811 DOI: 10.1016/j.neures.2015.10.009] [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: 08/03/2015] [Revised: 09/26/2015] [Accepted: 10/23/2015] [Indexed: 11/19/2022]
Abstract
Unipolar brush cells (UBCs) are excitatory interneurons in the granular layer of the cerebellar cortex, which are predominantly distributed in the vestibulo-cerebellar region. The unique firing properties and synaptic connections of UBCs may underlie lobular heterogeneity of excitability in the granular layer and the susceptibility to ischemia-induced excitotoxicity. In this study, we investigated the effects of oxygen-glucose deprivation (OGD) on the firing properties of UBCs and granule cells and spontaneous excitatory postsynaptic currents (sEPSCs) of Purkinje cells using whole-cell recordings. Short-term OGD induced increases in spontaneous firing of UBCs by causing membrane depolarization via the activation of NMDA receptors. UBC firing indirectly affected Purkinje cells by altering parallel fiber inputs of a subset granule cells, resulting in a marked increase in sEPSCs in Purkinje cells in vestibulo-cerebellar lobules IX-X, but not in lobules IV-VI, which have fewer UBCs. Similarly, the frequency and amplitude of sEPSCs in Purkinje cells were significantly greater in lobules IX-X than in IV-VI, even in control conditions. These results reveal that UBCs play key roles in regulating local excitability in the granular layer, resulting in lobular heterogeneity in the susceptibility to ischemic insult in the cerebellum.
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Affiliation(s)
- Yukihiro Takayasu
- Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan.
| | - Masato Shino
- Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Osamu Nikkuni
- Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Yukari Yoshida
- Gunma University Heavy Ion Medical Center, Maebashi, Gunma 371-8511, Japan
| | - Nobuhiko Furuya
- Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Kazuaki Chikamatsu
- Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
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13
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Cvetanovic M. Decreased expression of glutamate transporter GLAST in Bergmann glia is associated with the loss of Purkinje neurons in the spinocerebellar ataxia type 1. THE CEREBELLUM 2015; 14:8-11. [PMID: 25255716 DOI: 10.1007/s12311-014-0605-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited neurodegenerative disease of the cerebellum caused by a polyglutamine-repeat expansion in the protein ATXN1. We have previously demonstrated that astrocytic activation occurs early in pathogenesis, correlates with disease progression, and can occur when mutant ATXN1 expression is limited to Purkinje neurons. We now show that expression of glutamate and aspartate transporter, GLAST, is decreased in cerebellar astrocytes in a mouse model of SCA1. This decrease occurs in non-cell autonomous manner late in disease and correlates well with the loss of Purkinje neurons. Astrogliosis or decreased neuronal activity does not correlate with diminished GLAST expression. In addition, Bergmann glia remain capable of transcriptional upregulation of GLAST in response to improvement in Purkinje neurons supporting the notion of active neuron-glia crosstalk in disease.
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Affiliation(s)
- Marija Cvetanovic
- Department of Neuroscience, University of Minnesota, 2101 6th St SE, Minneapolis, 55455, MN, USA,
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Region-specific role for GluN2B-containing NMDA receptors in injury to Purkinje cells and CA1 neurons following global cerebral ischemia. Neuroscience 2014; 284:555-565. [PMID: 25450957 DOI: 10.1016/j.neuroscience.2014.10.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 10/13/2014] [Accepted: 10/14/2014] [Indexed: 01/04/2023]
Abstract
Motor deficits are present in cardiac arrest survivors and injury to cerebellar Purkinje cells (PCs) likely contribute to impairments in motor coordination and post-hypoxic myoclonus. N-Methyl-D-aspartic acid (NMDA) receptor-mediated excitotoxicity is a well-established mechanism of cell death in several brain regions, but the role of NMDA receptors in PC injury remains understudied. Emerging data in cortical and hippocampal neurons indicate that the GluN2A-containing NMDA receptors signal to improve cell survival and GluN2B-containing receptors contribute to neuronal injury. This study compared neuronal injury in the hippocampal CA1 region to that in PCs and investigated the role of NMDA receptors in PC injury in our mouse model of cardiac arrest and cardiopulmonary resuscitation (CA/CPR). Analysis of cell density demonstrated a 24% loss of PCs within 24 h after 8 min CA/CPR and injury stabilized to 33% by 7 days. The subunit promiscuous NMDA receptor antagonist MK-801 protected both CA1 neurons and PCs from ischemic injury following CA/CPR, demonstrating a role for NMDA receptor activation in injury to both brain regions. In contrast, the GluN2B antagonist, Co 101244, had no effect on PC loss while protecting against injury in the CA1 region. These data indicate that ischemic injury to cerebellar PCs progresses via different cell death mechanisms compared to hippocampal CA1 neurons.
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Krzyżanowska W, Pomierny B, Filip M, Pera J. Glutamate transporters in brain ischemia: to modulate or not? Acta Pharmacol Sin 2014; 35:444-62. [PMID: 24681894 DOI: 10.1038/aps.2014.1] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 01/03/2014] [Indexed: 01/18/2023] Open
Abstract
In this review, we briefly describe glutamate (Glu) metabolism and its specific transports and receptors in the central nervous system (CNS). Thereafter, we focus on excitatory amino acid transporters, cystine/glutamate antiporters (system xc-) and vesicular glutamate transporters, specifically addressing their location and roles in CNS and the molecular mechanisms underlying the regulation of Glu transporters. We provide evidence from in vitro or in vivo studies concerning alterations in Glu transporter expression in response to hypoxia or ischemia, including limited human data that supports the role of Glu transporters in stroke patients. Moreover, the potential to induce brain tolerance to ischemia through modulation of the expression and/or activities of Glu transporters is also discussed. Finally we present strategies involving the application of ischemic preconditioning and pharmacological agents, eg β-lactam antibiotics, amitriptyline, riluzole and N-acetylcysteine, which result in the significant protection of nervous tissues against ischemia.
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16
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mGluR1,5 activation protects cortical astrocytes and GABAergic neurons from ischemia-induced impairment. Neurosci Res 2013; 75:160-6. [DOI: 10.1016/j.neures.2012.12.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 10/02/2012] [Accepted: 12/11/2012] [Indexed: 11/22/2022]
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17
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Paine MG, Che D, Li L, Neumar RW. Cerebellar Purkinje cell neurodegeneration after cardiac arrest: Effect of therapeutic hypothermia. Resuscitation 2012; 83:1511-6. [DOI: 10.1016/j.resuscitation.2012.05.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 05/06/2012] [Accepted: 05/21/2012] [Indexed: 12/31/2022]
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18
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Liu Z, Huo W, Sun W, Lv M, Li F, Su Z. A sequential impairment of cortical astrocytes and GABAergic neurons during ischemia is improved by mGluR1,5 activation. Neurol Sci 2012; 34:1189-95. [DOI: 10.1007/s10072-012-1220-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 10/05/2012] [Indexed: 10/27/2022]
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19
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Comparative analyses of Purkinje cell gene expression profiles reveal shared molecular abnormalities in models of different polyglutamine diseases. Brain Res 2012; 1481:37-48. [PMID: 22917585 DOI: 10.1016/j.brainres.2012.08.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 08/01/2012] [Accepted: 08/01/2012] [Indexed: 01/24/2023]
Abstract
Polyglutamine (PolyQ) diseases have common features that include progressive selective neurodegeneration and the formation of protein aggregates. There is growing evidence to suggest that critical nuclear events lead to transcriptional alterations in PolyQ diseases such as spinocerebellar ataxia type 7 (SCA7) and Huntington's disease (HD), conditions which share a cerebellar degenerative phenotype. Taking advantage of laser capture microdissection technique, we compared the Purkinje cell (PC) gene expression profiles of two transgenic polyQ mouse models (HD: R6/2; SCA7: P7E) by microarray analysis that was validated by real time quantitative PCR. A large number of transcriptional alterations were detected in the R6/2 transgenic model of HD. Similar decreases in the same mRNAs, such as phospholipase C, β 3, purkinje cell protein 2 (Pcp2) and aldolase C, were found in both models. A decrease in aldolase C and phospholipase C, β 3, may lead to an increase in the vulnerability of PCs to excitotoxic events. Furthermore, downregulation of mRNAs mediated by the Pcp2-promoter is common in both models. Thus, our data reveal shared molecular abnormalities in different polyQ disorders.
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Abstract
In the CNS, excitatory amino acid transporters (EAATs) localized to neurons and glia terminate the actions of synaptically released glutamate. Whereas glial transporters are primarily responsible for maintaining low ambient levels of extracellular glutamate, neuronal transporters have additional roles in shaping excitatory synaptic transmission. Here we test the hypothesis that the expression level of the Purkinje cell (PC)-specific transporter, EAAT4, near parallel fiber (PF) release sites controls the extrasynaptic glutamate concentration transient following synaptic stimulation. Expression of EAAT4 follows a parasagittal banding pattern that allows us to compare regions of high and low EAAT4-expressing PCs. Using EAAT4 promoter-driven eGFP reporter mice together with pharmacology and genetic deletion, we show that the level of neuronal transporter expression influences extrasynaptic transmission from PFs to adjacent Bergmann glia (BG). Surprisingly, a twofold difference in functional EAAT4 levels is sufficient to alter signaling to BG, although EAAT4 may only be responsible for removing a fraction of released glutamate. These results demonstrate that physiological regulation of neuronal transporter expression can alter extrasynaptic neuroglial signaling.
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Hagiwara A, Tanaka Y, Hikawa R, Morone N, Kusumi A, Kimura H, Kinoshita M. Submembranous septins as relatively stable components of actin-based membrane skeleton. Cytoskeleton (Hoboken) 2011; 68:512-25. [PMID: 21800439 DOI: 10.1002/cm.20528] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Revised: 07/21/2011] [Accepted: 07/21/2011] [Indexed: 12/19/2022]
Abstract
The cell cortex is organized by the dynamic interplay between the plasma membrane, membrane proteins, and the cytoskeleton. Despite the cortical localization of septin heteropolymers in vivo and their direct interaction with phospholipid membranes in vitro, their behavior and roles remain elusive. This study characterizes the major cortical septin assembly found in mammalian tissue culture cells by fluorescence recovery after photobleaching analysis. GFP-tagged septin subunits, which colocalized with cortical actin, exhibited slower turnover than some other cortical proteins that were analyzed (e.g., actin, syntaxin-1A and a glutamate aspartate transporter [GLAST]). Perturbation of actin turnover by cytochalasin D or jasplakinolide retarded the cortical septin turnover, while septin depletion by RNAi did not recognizably affect cortical actin turnover. These phenomena are compatibly interpreted by septins' selective association with a subset of actin-based membrane skeleton, as revealed by rapid-freeze deep-etch immuno-replica electron microscopy. We applied the assay system to test septins' presumptive scaffold function on their physiological binding partners. Septin filament destabilization by RNAi-mediated subunit depletion facilitated the turnover of GLAST, depending on the carboxyl-terminal 29 residues, while a septin filament-stabilizing drug forchlorfenuron restrained more GLAST in the unexchangeable fraction. These data indicate that cortical septin heteropolymers are components of the actin-based membrane skeleton providing scaffolds for their interacting partners probably by impeding their lateral diffusion. We predict that diverse submembranous septin clusters found in vivo may serve as scaffolds or reserve pools for specific membrane-bound proteins.
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Affiliation(s)
- Akari Hagiwara
- Biochemistry and Cell Biology Unit, HMRO, Kyoto University Graduate School of Medicine, Japan
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22
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Acupuncture to point Baihui prevents ischemia-induced functional impairment of cortical GABAergic neurons. J Neurol Sci 2011; 307:139-43. [PMID: 21570693 DOI: 10.1016/j.jns.2011.04.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 04/22/2011] [Indexed: 11/23/2022]
Abstract
Ischemia impairs brain function and networks, in which the vulnerability of GABAergic neurons causes neural excitotoxicity and nerve cell death. Acupuncture presumably improves the outcome of stroke patients; however, cellular mechanisms underlying this improvement remain to be elusive. We have investigated whether electrical stimuli to acupoint Baihui prevent ischemia- induced impairment of cortical GABAergic neurons. After acupuncture to a Baihui-point of mice for a week, we examined the responses of cortical GABAergic neurons to ischemia by whole-cell recording. Compared with the data from a group of ischemia only, the acupuncture prevents the impairments of spike encoding and synaptic transmission at GABAergic neurons from ischemia. This prevention is associated with the resistance of these cells to ischemia-induced changes in spike threshold potentials and refractory periods Therefore, acupuncture to Baihui-point improves ischemic stroke via preventing the impairment of cortical GABAergic neurons.
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Boneva NB, Mori Y, Kaplamadzhiev DB, Kikuchi H, Zhu H, Kikuchi M, Tonchev AB, Yamashima T. Differential expression of FABP 3, 5, 7 in infantile and adult monkey cerebellum. Neurosci Res 2010; 68:94-102. [PMID: 20620177 DOI: 10.1016/j.neures.2010.07.2028] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 06/25/2010] [Accepted: 07/02/2010] [Indexed: 10/19/2022]
Abstract
To clarify the involvement of fatty acid binding proteins (FABPs) in cerebellar development and function, we explored the distribution of three brain-expressed FABPs, FABP 3, 5 and 7, by comparing three animal groups--infantile, normal and postischemic adult monkeys. Immunoblotting analysis revealed intense expression of FABP 3 and 7, but not of FABP5, in the control and postischemic adult cerebellum. The protein levels of FABP7, but not of FABP 3 or 5, gradually increased until 2 weeks after the insult. Immunohistochemical analysis showed that cerebellar FABP3-positive cells were Purkinje cells and Bergmann glia. FABP5-positive cells were found only in the postischemic cerebellum, and were identified as activated microglia. Interestingly, in the infantile cerebellum, both the granule cell progenitors in the external granular layer (EGL) and the oligodendrocyte progenitors in the internal granular layer (IGL) expressed FABP5. In the adult cerebellum, FABP7 was expressed in Purkinje cells and basket interneurons, while in the infantile cerebellum it was also found in Bergmann glia. These results showed differential expression of FABPs in cerebellar neuronal and glial cell types; FABP 3 and 7 were predominantly expressed in normal cerebellum, FABP5 after ischemic injury, while FABP 3, 5 and 7 were expressed during cerebellar development.
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Affiliation(s)
- Nadezhda B Boneva
- Department of Restorative Neurosurgery, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
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24
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Loss of beta-III spectrin leads to Purkinje cell dysfunction recapitulating the behavior and neuropathology of spinocerebellar ataxia type 5 in humans. J Neurosci 2010; 30:4857-67. [PMID: 20371805 DOI: 10.1523/jneurosci.6065-09.2010] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Mutations in SPTBN2, the gene encoding beta-III spectrin, cause spinocerebellar ataxia type 5 in humans (SCA5), a neurodegenerative disorder resulting in loss of motor coordination. How these mutations give rise to progressive ataxia and what the precise role beta-III spectrin plays in normal cerebellar physiology are unknown. We developed a mouse lacking full-length beta-III spectrin and found that homozygous mice reproduced features of SCA5 including gait abnormalities, tremor, deteriorating motor coordination, Purkinje cell loss, and cerebellar atrophy (molecular layer thinning). In vivo analysis reveals an age-related reduction in simple spike firing rate in surviving beta-III(-/-) Purkinje cells, whereas in vitro studies show these neurons to have reduced spontaneous firing, smaller sodium currents, and dysregulation of glutamatergic neurotransmission. Our data suggest an early loss of EAAT4- (protein interactor of beta-III spectrin) and a subsequent loss of GLAST-mediated uptake may play a role in neuronal pathology. These findings implicate a loss of beta-III spectrin function in SCA5 pathogenesis and indicate that there are at least two physiological effects of beta-III spectrin loss that underpin a progressive loss of inhibitory cerebellar output, namely an intrinsic Purkinje cell membrane defect due to reduced sodium currents and alterations in glutamate signaling.
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25
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Gugger OS, Kapfhammer JP. Reduced size of the dendritic tree does not protect Purkinje cells from excitotoxic death. J Neurosci Res 2010; 88:774-83. [PMID: 19798747 DOI: 10.1002/jnr.22247] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Purkinje cell loss by excitotoxic damage is a typical finding in many cerebellar diseases. One important aspect of this high sensitivity of Purkinje cells to excitotoxic death might be the enormous size of their dendritic tree, with a high load of excitatory glutamate receptors. We have studied whether reduction in the size of the dendritic tree might confer resistance against excitotoxic death to Purkinje cells. We have grown Purkinje cells in organotypic cerebellar slice cultures under chronic activation of metabotropic glutamate receptors or of protein kinase C. Both treatments strongly reduced dendritic tree size. After this treatment, cells were exposed to the glutamate receptor agonist AMPA, which has a strong excitotoxic effect on Purkinje cells. We found that Purkinje cells with small dendritic trees were as sensitive to AMPA exposure as untreated control cells with large dendritic trees. Immunostaining against vesicular glutamate transporter 1 revealed that the small dendritic trees were densely covered by glutamatergic terminals. Our results indicate that the expansion of the dendritic tree and the total number of AMPA receptors per neuron do not play a major role in determining the susceptibility of Purkinje cells to excitotoxic death.
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Affiliation(s)
- Olivia S Gugger
- Anatomical Institute, Department of Biomedicine, University of Basel, Basel, Switzerland
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26
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Huang L, Chen N, Ge M, Zhu Y, Guan S, Wang JH. Ca2+ and acidosis synergistically lead to the dysfunction of cortical GABAergic neurons during ischemia. Biochem Biophys Res Commun 2010; 394:709-14. [PMID: 20227392 DOI: 10.1016/j.bbrc.2010.03.056] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2010] [Accepted: 03/09/2010] [Indexed: 10/19/2022]
Abstract
Cell death in cerebral ischemia is presumably initiated by neural excitotoxicity resulted from the dysfunction of inhibitory neurons in early stage. Molecular processes underlying the ischemic injury of inhibitory neurons remain to be elusive, which we investigated by biochemical manipulations with cellular imaging and patch clamp at GFP-labeled GABAergic cells in cortical slices. Ischemia induces Ca(2+) elevation, acidosis and dysfunction in GABAergic cells. An elevation of cytoplasmic Ca(2+) or H(+) impairs the encoding of action potentials in these neurons. The effects of Ca(2+) and H(+) are additive in nature and occlude ischemic outcomes. Ischemia impairs spike production through prolonging spike refractory periods and raising threshold potentials. Therefore, calcium toxicity and acidosis during ischemia synergistically impair the dynamics of sodium channels and function of cortical GABAergic neurons, which lead to neural excitotoxicity. Our results also suggest that the cocktail therapeutics is needed to prevent neuronal death from ischemia.
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Affiliation(s)
- Li Huang
- Department of Physiology, Bengbu Medical College, Bengbu Anhui 233000, China
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Sachs AJ, David SA, Haider NB, Nystuen AM. Patterned neuroprotection in the Inpp4a(wbl) mutant mouse cerebellum correlates with the expression of Eaat4. PLoS One 2009; 4:e8270. [PMID: 20011524 PMCID: PMC2788419 DOI: 10.1371/journal.pone.0008270] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Accepted: 10/05/2009] [Indexed: 12/03/2022] Open
Abstract
The weeble mutant mouse has a frame shift mutation in inositol polyphosphate 4-phosphatase type I (Inpp4a). The phenotype is characterized by an early onset cerebellar ataxia and neurodegeneration, especially apparent in the Purkinje cells. Purkinje cell loss is a common pathological finding in many human and mouse ataxic disorders. Here we show that in the Inpp4awbl mutant, Purkinje cells are lost in a specific temporal and spatial pattern. Loss occurs early in postnatal development; however, prior to the appearance of climbing fibers in the developing molecular layer, the mutant has a normal complement of Purkinje cells and they are properly positioned. Degeneration and reactive gliosis are present at postnatal day 5 and progress rapidly in a defined pattern of patches; however, Inpp4a is expressed uniformly across Purkinje cells. In late stage mutants, patches of surviving Purkinje cells appear remarkably normal with the exception that the climbing fibers have been excessively eliminated. Surviving Purkinje cells express Eaat4, a glutamate transporter that is differentially expressed in subsets of Purkinje cells during development and into adult stages. Prior to Purkinje cell loss, reactive gliosis and dendritic atrophy can be seen in Eaat4 negative stripes. Our data suggest that Purkinje cell loss in the Inpp4awbl mutant is due to glutamate excitotoxicity initiated by the climbing fiber, and that Eaat4 may exert a protective effect.
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Affiliation(s)
- Andrew J. Sachs
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Samuel A. David
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Neena B. Haider
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- * E-mail: (AMN); (NBH)
| | - Arne M. Nystuen
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- * E-mail: (AMN); (NBH)
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Young age and low temperature, but not female gender delay ATP loss and glutamate release, and protect Purkinje cells during simulated ischemia in cerebellar slices. Neuropharmacology 2009; 58:392-403. [PMID: 19825379 DOI: 10.1016/j.neuropharm.2009.09.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 09/03/2009] [Accepted: 09/24/2009] [Indexed: 11/20/2022]
Abstract
Excessive activation of glutamate receptors contributes to Purkinje cell (PC) damage during brain ischemia, but the mechanisms of glutamate release are contentious. Age, gender and temperature all strongly influence ischemic brain damage, but the mechanisms underlying their influence are not fully understood. We determined how age, gender and temperature influence ATP loss, glutamate release, glutamate receptor activation and PC damage during cerebellar ischemia. We used voltage-clamped PCs to monitor glutamate release during simulated ischemia in slices of cerebellum of different ages and genders, and at different temperatures. While gender did not affect ischemic glutamate release, both young age and low temperature dramatically delayed the onset of glutamate release without affecting its magnitude. Glutamate receptor and transporter density were similar around young and old PCs, but the rate of ATP decline during ischemia was dramatically slowed in young animals and by lowered temperature. Bypassing the ischemia-induced loss of ATP, and disrupting ionic gradients directly by pharmacologically inhibiting the Na(+)/K(+)-ATPase, reduced the difference in timing of glutamate release in newborn and mature cerebellum. Ischemic damage in newborn and mature cerebellum paralleled ATP loss and glutamate release, but blocking glutamate receptors did not prevent ischemic damage. Thus, protection against brain ischemia provided by young age or lowered temperature is due to slower consumption and hence delayed loss of ATP, with a corresponding delay in glutamate release and other undetermined damage mechanisms. The protection afforded by female gender must occur downstream of ATP decline, glutamate release, and activation of glutamate receptors on PCs.
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Bigdeli MR, Rahnema M, Khoshbaten A. Preconditioning with Sublethal Ischemia or Intermittent Normobaric Hyperoxia Up-regulates Glutamate Transporters and Tumor Necrosis Factor-α Converting Enzyme in the Rat Brain. J Stroke Cerebrovasc Dis 2009; 18:336-42. [DOI: 10.1016/j.jstrokecerebrovasdis.2008.12.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Revised: 11/26/2008] [Accepted: 12/16/2008] [Indexed: 12/22/2022] Open
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Sodhi M, Wood KH, Meador-Woodruff J. Role of glutamate in schizophrenia: integrating excitatory avenues of research. Expert Rev Neurother 2008; 8:1389-406. [PMID: 18759551 DOI: 10.1586/14737175.8.9.1389] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Schizophrenia is a debilitating lifelong disorder affecting up to 1% of the population worldwide, producing significant financial and emotional hardship for patients and their families. As yet, the causes of schizophrenia and the mechanism of action of antipsychotic drugs are unknown, and many patients do not respond well to currently available medications. Attempts to find risk factors for the disorder using epidemiological methods have shown that schizophrenia is highly heritable, and path analyses predict that the disorder is caused by several genes in combination with nongenetic factors. Therefore, intensive research efforts have been made to identify genes creating vulnerability to schizophrenia and also genes predicting response to treatment. Interactions of the glutamatergic system with dopaminergic and serotonergic circuitry are crucial for normal brain function, and their disruption may be a mechanism by which the pathophysiology of schizophrenia is manifest. Genes within the glutamatergic system are therefore strong candidates for investigation, and these include the glutamate receptor genes in addition to genes encoding neuregulin, dysbindin, D-amino acid oxidase and G72/G30. These genetic studies could eventually reveal new targets for antipsychotic drug treatment, which currently focuses on inhibition of the dopaminergic system. However, a recent breakthrough indicates clinical efficacy of a drug stimulating the metabotropic glutamate receptor II, LY2140023, which has improved efficacy for negative and cognitive symptoms of schizophrenia. Studies of larger patient samples are required to consolidate these data. Further investigation of glutamatergic targets is likely to reinvigorate antipsychotic drug development.
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Affiliation(s)
- Monsheel Sodhi
- Department of Psychiatry & Behavioral Neurobiology, University of Alabama at Birmingham, 1720 7th Avenue Sth, Rm 590C CIRC, Birmingham, AL 35294, USA.
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Massie A, Cnops L, Smolders I, McCullumsmith R, Kooijman R, Kwak S, Arckens L, Michotte Y. High-affinity Na+/K+-dependent glutamate transporter EAAT4 is expressed throughout the rat fore- and midbrain. J Comp Neurol 2008; 511:155-72. [DOI: 10.1002/cne.21823] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Hertz L. Bioenergetics of cerebral ischemia: a cellular perspective. Neuropharmacology 2008; 55:289-309. [PMID: 18639906 DOI: 10.1016/j.neuropharm.2008.05.023] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 05/14/2008] [Accepted: 05/14/2008] [Indexed: 12/27/2022]
Abstract
In cerebral ischemia survival of neurons, astrocytes, oligodendrocytes and endothelial cells is threatened during energy deprivation and/or following re-supply of oxygen and glucose. After a brief summary of characteristics of different cells types, emphasizing the dependence of all on oxidative metabolism, the bioenergetics of focal and global ischemia is discussed, distinguishing between events during energy deprivation and subsequent recovery attempt after re-circulation. Gray and white matter ischemia are described separately, and distinctions are made between mature and immature brains. Next comes a description of bioenergetics in individual cell types in culture during oxygen/glucose deprivation or exposure to metabolic inhibitors and following re-establishment of normal aerated conditions. Due to their expression of NMDA and non-NMDA receptors neurons and oligodendrocytes are exquisitely sensitive to excitotoxicity by glutamate, which reaches high extracellular concentrations in ischemic brain for several reasons, including failing astrocytic uptake. Excitotoxicity kills brain cells by energetic exhaustion (due to Na(+) extrusion after channel-mediated entry) combined with mitochondrial Ca(2+)-mediated injury and formation of reactive oxygen species. Many (but not all) astrocytes survive energy deprivation for extended periods, but after return to aerated conditions they are vulnerable to mitochondrial damage by cytoplasmic/mitochondrial Ca(2+) overload and to NAD(+) deficiency. Ca(2+) overload is established by reversal of Na(+)/Ca(2+) exchangers following Na(+) accumulation during Na(+)-K(+)-Cl(-) cotransporter stimulation or pH regulation, compensating for excessive acid production. NAD(+) deficiency inhibits glycolysis and eventually oxidative metabolism, secondary to poly(ADP-ribose)polymerase (PARP) activity following DNA damage. Hyperglycemia can be beneficial for neurons but increases astrocytic death due to enhanced acidosis.
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Affiliation(s)
- Leif Hertz
- College of Basic Medical Sciences, China Medical University, Shenyang, PR China.
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36
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Excitatory amino acid transporter expression by astrocytes is neuroprotective against microglial excitotoxicity. Brain Res 2008; 1210:11-9. [DOI: 10.1016/j.brainres.2008.03.012] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Revised: 02/25/2008] [Accepted: 03/03/2008] [Indexed: 11/20/2022]
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37
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Bigdeli MR, Hajizadeh S, Froozandeh M, Heidarianpour A, Rasoulian B, Asgari AR, Pourkhalili K, Khoshbaten A. Normobaric hyperoxia induces ischemic tolerance and upregulation of glutamate transporters in the rat brain and serum TNF-alpha level. Exp Neurol 2008; 212:298-306. [PMID: 18538765 DOI: 10.1016/j.expneurol.2008.03.029] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 03/11/2008] [Accepted: 03/31/2008] [Indexed: 01/13/2023]
Abstract
Recent studies suggest that intermittent and prolonged normobaric hyperoxia (HO) results in ischemic tolerance to reduce ischemic brain injury. In this research, we attempted to see changes in excitatory amino acid transporters (EAATs) and TNF-alpha levels following prolonged and intermittent hyperoxia preconditioning. Rats were divided into four experimental groups, each of 21 animals. The first two were exposed to 95% inspired HO for 4 h/day for 6 consecutive days (intermittent HO, InHO) or for 24 continuous hours (prolonged HO, PrHO). The second two groups acted as controls, and were exposed to 21% oxygen in the same chamber. Each main group was subdivided to middle cerebral artery occlusion (MCAO-operated), sham-operated (without MCAO), and intact (without any surgery) subgroups. After 24 h from pretreatment, MCAO-operated subgroups were subjected to 60 min of right MCAO. After 24 h reperfusion, neurologic deficit score (NDS) and infarct volume were measured in MCAO-operated subgroups. EAATs expression and serum TNF-alpha levels were assessed in sham-operated and intact subgroups. Preconditioning with prolonged and intermittent HO decreased NDS and upregulated EAAT1, EAAT2, and EAAT3 and increased serum TNF-alpha levels significantly. Although further studies are needed to clarify the mechanisms of ischemic tolerance, the intermittent and prolonged HO seems to partly exert their effects via increase serum TNF-alpha levels and upregulation of EAATs.
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Zhao S, Chen N, Yang Z, Huang L, Zhu Y, Guan S, Chen Q, Wang JH. Ischemia deteriorates the spike encoding of rat cerebellar Purkinje cells by raising intracellular Ca2+. Biochem Biophys Res Commun 2008; 366:401-7. [DOI: 10.1016/j.bbrc.2007.11.173] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Accepted: 11/23/2007] [Indexed: 10/22/2022]
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Chen MH, Liu TW, Xie L, Song FQ, He T, Mo SR, Zeng ZY. A simpler cardiac arrest model in the mouse. Resuscitation 2007; 75:372-9. [PMID: 17566627 DOI: 10.1016/j.resuscitation.2007.04.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 04/02/2007] [Accepted: 04/06/2007] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Delivering alternating currency (AC) to right ventricular endocardium to induce ventricular fibrillation (VF) in mice is complicated. We tried to validate whether transoesophageal AC stimulation could induce VF and how long AC stimulation had to be sustained to prevent the spontaneous cardioversion of VF in mice. METHODS A pacing electrode was inserted orally into the oesophagus and AC was delivered to esophagus through the pacing electrode to stimulate the heart and induce VF in 15 mice. The incidence of VF and time of AC stimulation were recorded 4min after onset of VF cardiopulmonary resuscitation (CPR) was started. RESULTS VF was induced by short AC stimulation in all 15 mice. With the prolongation of AC stimulation, the incidences of spontaneous cardioversion of VF decreased whereas the incidence of pulseless electrical activity (PEA) increased accordingly. Following the termination of prolonged AC stimulation, VF occurred only in 1 of 15 mice, but PEA in 14 of 15 mice. Before CPR 1 of 15 and 12 of 15 animals remained in VF and in PEA, respectively, while 2 of 15 animals developed into asystole. After CPR, 11 of 15 animals were successfully resuscitated. CONCLUSION VF can be induced by a short period of transoesophageal AC stimulation in mice. However, prolonged AC stimulation is prone to induce PEA other than VF. Nonetheless, the development of a mouse CA model in this manner is simpler and easier, which may have practical significance for facilitating experimental investigation on CA and CPR.
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Affiliation(s)
- Meng-Hua Chen
- Institute of Cardiovascular Diseases, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China.
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Rajamanickam J, Palmada M, Lang F, Boehmer C. EAAT4 phosphorylation at the SGK1 consensus site is required for transport modulation by the kinase. J Neurochem 2007; 102:858-66. [PMID: 17442044 DOI: 10.1111/j.1471-4159.2007.04585.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
EAAT4 (SLC1A6) is a Purkinje-Cell-specific post-synaptic excitatory amino acid transporter that plays a major role in clearing synaptic glutamate. EAAT4 abundance and function is known to be modulated by the serum and glucocorticoid inducible kinase (SGK) 1 but the precise mechanism of kinase action has not been defined yet. The present work aims to identify the molecular mechanism of EAAT4 modulation by the kinase. The EAAT4 sequence bears two putative SGK1 consensus sites (at Thr40 and Thr504) at the amino and carboxy terminus that are conserved among species. Expression studies in Xenopus oocytes demonstrated that EAAT4-mediated [(3)H] glutamate uptake and cell surface abundance are enhanced by co-expression of SGK1. Disruption of the SGK1 phosphorylation site at threonine 40 ((T40A)EAAT4) or of both phosphorylation sites ((T40AT504A)EAAT4) abrogated the effect of SGK1 on transporter function and expression. SGK1 modulates several transport proteins via inhibition of the ubiquitin ligase Nedd4-2. Co-expression of Nedd4-2 inhibited wild-type EAAT4 but not the (T40AT504A)EAAT4 mutant. Besides, RNA interference-mediated reduction of endogenous Nedd4-2 (xNedd4-2) expression increased the activity of the transporter. In conclusion, maximal glutamate transport modulation by SGK1 is accomplished by direct EAAT4 stimulation and to a lesser extent by inhibition of intrinsic Nedd4-2.
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Ardeshiri A, Kelley MH, Korner IP, Hurn PD, Herson PS. Mechanism of progesterone neuroprotection of rat cerebellar Purkinje cells following oxygen-glucose deprivation. Eur J Neurosci 2007; 24:2567-74. [PMID: 17100844 PMCID: PMC2831653 DOI: 10.1111/j.1460-9568.2006.05142.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The survival of rat Purkinje cell (PCs) cerebellar cultures was used to test the hypothesis that progesterone is protective against oxygen-glucose deprivation through potentiation of GABA(A) receptor activity. Electrophysiological recordings confirm that PCs develop robust excitatory and inhibitory synapses in culture. Exposure of cultured PCs to increasing concentrations of progesterone during oxygen-glucose deprivation revealed a concentration-dependent protection by progesterone, with significant protection observed at physiological concentrations, as low as 10 nm. The concurrent application of the GABA(A) receptor antagonist picrotoxin (100 microm) completely abolished the neuroprotection afforded by progesterone, indicating that progesterone is neuroprotective through activation of GABA(A) receptors. Progesterone potentiates GABA(A) receptor activity indirectly through its metabolites, such as allopregnanolone (ALLO). Therefore, ALLO was applied to PC cultures and was observed to produce significant protection at all concentrations tested, from 10 to 1000 nm. Finally, the inhibition of progesterone metabolism with finasteride abolished the protection afforded by progesterone without having any effect on the neuroprotection caused by ALLO. These data indicate that progesterone protects cerebellar PCs at physiological concentrations through a GABA-active metabolite.
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Affiliation(s)
- A Ardeshiri
- Department of Anesthesioloy and Peri-Operative Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97201, USA
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