101
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Lussier MP, Sanz-Clemente A, Roche KW. Dynamic Regulation of N-Methyl-d-aspartate (NMDA) and α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) Receptors by Posttranslational Modifications. J Biol Chem 2015; 290:28596-603. [PMID: 26453298 DOI: 10.1074/jbc.r115.652750] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Many molecular mechanisms underlie the changes in synaptic glutamate receptor content that are required by neuronal networks to generate cellular correlates of learning and memory. During the last decade, posttranslational modifications have emerged as critical regulators of synaptic transmission and plasticity. Notably, phosphorylation, ubiquitination, and palmitoylation control the stability, trafficking, and synaptic expression of glutamate receptors in the central nervous system. In the current review, we will summarize some of the progress made by the neuroscience community regarding our understanding of phosphorylation, ubiquitination, and palmitoylation of the NMDA and AMPA subtypes of glutamate receptors.
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Affiliation(s)
- Marc P Lussier
- From the Département de Chimie, Université du Québec à Montréal, Montréal, Québec H3C 3P8, Canada
| | - Antonio Sanz-Clemente
- the Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, and
| | - Katherine W Roche
- the Receptor Biology Section, NINDS, National Institutes of Health, Bethesda, Maryland 20892
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102
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O'Dell TJ, Connor SA, Guglietta R, Nguyen PV. β-Adrenergic receptor signaling and modulation of long-term potentiation in the mammalian hippocampus. ACTA ACUST UNITED AC 2015; 22:461-71. [PMID: 26286656 PMCID: PMC4561407 DOI: 10.1101/lm.031088.113] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 06/02/2015] [Indexed: 02/06/2023]
Abstract
Encoding new information in the brain requires changes in synaptic strength. Neuromodulatory transmitters can facilitate synaptic plasticity by modifying the actions and expression of specific signaling cascades, transmitter receptors and their associated signaling complexes, genes, and effector proteins. One critical neuromodulator in the mammalian brain is norepinephrine (NE), which regulates multiple brain functions such as attention, perception, arousal, sleep, learning, and memory. The mammalian hippocampus receives noradrenergic innervation and hippocampal neurons express β-adrenergic receptors, which are known to play important roles in gating the induction of long-lasting forms of synaptic potentiation. These forms of long-term potentiation (LTP) are believed to importantly contribute to long-term storage of spatial and contextual memories in the brain. In this review, we highlight the contributions of noradrenergic signaling in general and β-adrenergic receptors in particular, toward modulating hippocampal LTP. We focus on the roles of NE and β-adrenergic receptors in altering the efficacies of specific signaling molecules such as NMDA and AMPA receptors, protein phosphatases, and translation initiation factors. Also, the roles of β-adrenergic receptors in regulating synaptic "tagging" and "capture" of LTP within synaptic networks of the hippocampus are reviewed. Understanding the molecular and cellular bases of noradrenergic signaling will enrich our grasp of how the brain makes new, enduring memories, and may shed light on credible strategies for improving mental health through treatment of specific disorders linked to perturbed memory processing and dysfunctional noradrenergic synaptic transmission.
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Affiliation(s)
- Thomas J O'Dell
- Department of Physiology, David Geffen School of Medicine and Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, Los Angeles, California 90095, USA
| | - Steven A Connor
- Department of Physiology, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada
| | - Ryan Guglietta
- Interdepartmental Ph.D. Program for Neuroscience, University of California, Los Angeles, Los Angeles, California 90095, USA
| | - Peter V Nguyen
- Department of Physiology, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada Department of Psychiatry, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada Department of Neuroscience & Mental Health Institute, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada
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103
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Ribeiro FC, Santos LE, Ferreira ST. USP46: a new piece of the memory puzzle? J Neurochem 2015; 134:979-81. [PMID: 26237995 DOI: 10.1111/jnc.13227] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 06/30/2015] [Indexed: 01/26/2023]
Abstract
Long-term potentiation (LTP) and long-term depression (LTD) are crucial for synaptic plasticity, and are driven by AMPA receptor (AMPAR) trafficking. Recent findings indicate that the ubiquitin-proteasome system, the main protein degradation machinery of the cell, plays a significant role in memory formation by regulating the induction and maintenance of LTP. Although previously suggested as a possibility, deubiquitination of mammalian AMPARs had not been demonstrated, and the search for an enzyme that mediates the processes continued. This Editorial Highlight discusses the relevance of a study published in the current issue of Journal of Neurochemistry, in which the authors Huo and collaborators now identified ubiquitin-specific peptidase 46 (USP46) as a specific AMPAR deubiquitinase.
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Affiliation(s)
- Felipe C Ribeiro
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Luis E Santos
- Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Sergio T Ferreira
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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104
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Membrane-derived phospholipids control synaptic neurotransmission and plasticity. PLoS Biol 2015; 13:e1002153. [PMID: 25996636 PMCID: PMC4440815 DOI: 10.1371/journal.pbio.1002153] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 04/15/2015] [Indexed: 12/15/2022] Open
Abstract
Synaptic communication is a dynamic process that is key to the regulation of neuronal excitability and information processing in the brain. To date, however, the molecular signals controlling synaptic dynamics have been poorly understood. Membrane-derived bioactive phospholipids are potential candidates to control short-term tuning of synaptic signaling, a plastic event essential for information processing at both the cellular and neuronal network levels in the brain. Here, we showed that phospholipids affect excitatory and inhibitory neurotransmission by different degrees, loci, and mechanisms of action. Signaling triggered by lysophosphatidic acid (LPA) evoked rapid and reversible depression of excitatory and inhibitory postsynaptic currents. At excitatory synapses, LPA-induced depression depended on LPA1/Gαi/o-protein/phospholipase C/myosin light chain kinase cascade at the presynaptic site. LPA increased myosin light chain phosphorylation, which is known to trigger actomyosin contraction, and reduced the number of synaptic vesicles docked to active zones in excitatory boutons. At inhibitory synapses, postsynaptic LPA signaling led to dephosphorylation, and internalization of the GABAAγ2 subunit through the LPA1/Gα12/13-protein/RhoA/Rho kinase/calcineurin pathway. However, LPA-induced depression of GABAergic transmission was correlated with an endocytosis-independent reduction of GABAA receptors, possibly by GABAAγ2 dephosphorylation and subsequent increased lateral diffusion. Furthermore, endogenous LPA signaling, mainly via LPA1, mediated activity-dependent inhibitory depression in a model of experimental synaptic plasticity. Finally, LPA signaling, most likely restraining the excitatory drive incoming to motoneurons, regulated performance of motor output commands, a basic brain processing task. We propose that lysophospholipids serve as potential local messengers that tune synaptic strength to precedent activity of the neuron. Lysophospholipids derived from membranes are important regulators of neurotransmission, acting as local messengers that couple synaptic strength to recent neuronal activity. Neuronal networks are modules of synaptic connectivity that underlie all brain functions, from simple reflexes to complex cognitive processes. Synaptic plasticity allows these networks to adapt to changing external and internal environments. Membrane-derived bioactive phospholipids are potential candidates to control short-term synaptic plasticity. We demonstrate that lysophosphatidic acid (LPA), an important intermediary in lipid metabolism, depresses the main excitatory and inhibitory synaptic systems by different mechanisms. LPA depresses inhibitory synaptic transmission by reducing the number of postsynaptic receptors at inhibitory synapses; whereas it depresses excitatory synaptic transmission by decreasing the size of the ready-to-use synaptic vesicle pool at excitatory terminals. Finally, we demonstrate that LPA signaling contributes to the performance of motor output commands in adult animals. Our data documents that synaptic strength and neuronal activity are modulated by products of membrane phospholipid metabolism, which suggests that bioactive phospholipids are candidates in coupling brain function to the metabolic status of the organism.
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105
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Ghafari M, Keihan Falsafi S, Höger H, Bennett KL, Lubec G. Identification of new phosphorylation sites of AMPA receptors in the rat hippocampus--A resource for neuroscience research. Proteomics Clin Appl 2015; 9:808-16. [PMID: 25656447 DOI: 10.1002/prca.201400057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 10/16/2014] [Accepted: 02/03/2015] [Indexed: 12/14/2022]
Abstract
PURPOSE AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptors (AMPARs) are glutamate-gated ion channels that mediate the majority of fast excitatory synaptic transmissions in the mammalian brain. A series of phosphorylation sites have been predicted or identified and knowledge on phosphorylations is mandatory for understanding receptor biology and functions. EXPERIMENTAL DESIGN Immunoprecipitation from extracted hippocampal rat proteins was carried out using an antibody against the AMPAR GluA1 subunit, followed by identification of GluA1 and binding partners by MS. Bands from SDS-PAGE were picked, peptides were generated by trypsin and chymotrypsin digestion and identified by MS/MS (LTQ Orbitrap Velos). RESULTS Using Mascot as a search engine, phosphorylation sites S506, S645, S720, S849, S863, S895, T858, Y228, Y419, and T734 were found on GluA1; S357, S513, S656, S727, T243, T420, T741, Y 143, Y301,Y426 on GluA2; S301, S516, S657, S732, T222, and T746 were observed on GluA3; and S514, S653 was phosphorylated on GluA4. CONCLUSIONS AND CLINICAL RELEVANCE A series of additional protein modifications were observed and in particular, tyrosine and tryptophan nitrations on GluA1 were detected that may raise questions on additional regulation mechanisms for AMPARs in addition to phosphorylations. The findings are relevant for interpretation of previous work and design of future studies using AMPAR serving as a resource for neuroscience research and indeed, phosphorylations and PTMs per se would have to be respected when neuropathological and neurological disorders are being studied.
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Affiliation(s)
- Maryam Ghafari
- Department of Pediatrics, Medical University of Vienna, Vienna, Austria
| | | | - Harald Höger
- Core Unit of Biomedical Research, Division of Laboratory Animal Science and Genetics, Medical University of Vienna, Himberg, Austria
| | - Keiryn L Bennett
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Gert Lubec
- Department of Pediatrics, Medical University of Vienna, Vienna, Austria
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106
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Udagawa T, Fujioka Y, Tanaka M, Honda D, Yokoi S, Riku Y, Ibi D, Nagai T, Yamada K, Watanabe H, Katsuno M, Inada T, Ohno K, Sokabe M, Okado H, Ishigaki S, Sobue G. FUS regulates AMPA receptor function and FTLD/ALS-associated behaviour via GluA1 mRNA stabilization. Nat Commun 2015; 6:7098. [PMID: 25968143 PMCID: PMC4479014 DOI: 10.1038/ncomms8098] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Accepted: 04/02/2015] [Indexed: 12/12/2022] Open
Abstract
FUS is an RNA/DNA-binding protein involved in multiple steps of gene expression and is associated with amyotrophic lateral sclerosis (ALS) and fronto-temporal lobar degeneration (FTLD). However, the specific disease-causing and/or modifying mechanism mediated by FUS is largely unknown. Here we evaluate intrinsic roles of FUS on synaptic functions and animal behaviours. We find that FUS depletion downregulates GluA1, a subunit of AMPA receptor. FUS binds GluA1 mRNA in the vicinity of the 3′ terminus and controls poly (A) tail maintenance, thus regulating stability. GluA1 reduction upon FUS knockdown reduces miniature EPSC amplitude both in cultured neurons and in vivo. FUS knockdown in hippocampus attenuates dendritic spine maturation and causes behavioural aberrations including hyperactivity, disinhibition and social interaction defects, which are partly ameliorated by GluA1 reintroduction. These results highlight the pivotal role of FUS in regulating GluA1 mRNA stability, post-synaptic function and FTLD-like animal behaviours. FUS is an RNA/DNA-binding protein involved in gene expression regulation and associated with amyotrophic lateral sclerosis and frontotemporal dementia (FTLD) but the disease-causing mechanisms are unclear. Here the authors show that FUS regulates the stability of GluA1 mRNA and dendritic maturation and plays a role in FTLD-associated behaviours.
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Affiliation(s)
- Tsuyoshi Udagawa
- 1] Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan [2] Graduate School of pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Yusuke Fujioka
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Motoki Tanaka
- Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Daiyu Honda
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Satoshi Yokoi
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Yuichi Riku
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Daisuke Ibi
- Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Taku Nagai
- Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Kiyofumi Yamada
- Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Hirohisa Watanabe
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Toshifumi Inada
- Graduate School of pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Masahiro Sokabe
- Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Haruo Okado
- Department of Brain Development and Neural Regeneration, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Shinsuke Ishigaki
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Gen Sobue
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
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107
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Abstract
Dynamic changes in synaptic strength are thought to be critical for higher brain function such as learning and memory. Alterations in synaptic strength can result from modulation of AMPA receptor (AMPAR) function and trafficking to synaptic sites. The phosphorylation state of AMPAR subunits is one mechanism by which cells regulate receptor function and trafficking. Receptor phosphorylation is in turn regulated by extracellular signals; these include neuronal activity, neuropeptides, and neuromodulators such as dopamine and norepinephrine (NE). Although numerous studies have reported that the neuropeptide pituitary adenylate cyclase activating polypeptide 38 (PACAP38) alters hippocampal CA1 synaptic strength and GluA1 synaptic localization, its effect on AMPAR phosphorylation state has not been explored. We determined that PACAP38 stimulation of hippocampal cultures increased phosphorylation of S845, and decreased phosphorylation of T840 on the GluA1 AMPAR subunit. Increases in GluA1 S845 phosphorylation primarily occurred via PAC1 and VPAC2 receptor activation, whereas a reduction in GluA1 T840 phosphorylation was largely driven by PAC1 receptor activation and to a lesser extent by VPAC1 and VPAC2 receptor activation. GluA1 S845 phosphorylation could be blocked by a PKA inhibitor, and GluA1 T840 dephosphorylation could be blocked by a protein phosphatase 1/2A (PP1/PP2A) inhibitor and was partly blocked by a NMDA receptor (NMDAR) antagonist. These results demonstrate that the neuropeptide PACAP38 inversely regulates the phosphorylation of two distinct sites on GluA1 and may play an important role modulating AMPAR function and synaptic plasticity in the brain.
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108
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Xiong H, Krugers HJ. Tuning hippocampal synapses by stress-hormones: Relevance for emotional memory formation. Brain Res 2015; 1621:114-20. [PMID: 25907153 DOI: 10.1016/j.brainres.2015.04.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 02/20/2015] [Accepted: 04/08/2015] [Indexed: 01/20/2023]
Abstract
While stress is often associated with an increased risk to develop (psycho) pathology, the initial response after exposure to stressors is often highly beneficial and allows individuals to optimally cope with challenging situations. Various neurotransmitters and neuromodulators - such as catecholamines and glucocorticoids - are released upon exposure to stressors and regulate behavioural adaptation to stress and enhance the storage of salient information. Studies over the past years have revealed that catecholamines and glucocorticoids regulate synaptic function and synaptic plasticity - which underlie memory formation - in a highly dynamic manner. In this brief review we will summarise how catecholamines and glucocorticoids regulate synaptic function and discuss how these effects may contribute to acquisition and storage of emotional information. This article is part of a Special Issue entitled SI: Brain and Memory.
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Affiliation(s)
- Hui Xiong
- SILS-Center for Neuroscience, University of Amsterdam, The Netherlands.
| | - Harm J Krugers
- SILS-Center for Neuroscience, University of Amsterdam, The Netherlands
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109
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Hu Z, Zhao J, Hu T, Luo Y, Zhu J, Li Z. miR-501-3p mediates the activity-dependent regulation of the expression of AMPA receptor subunit GluA1. ACTA ACUST UNITED AC 2015; 208:949-59. [PMID: 25800054 PMCID: PMC4384731 DOI: 10.1083/jcb.201404092] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The number of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) in synapses determines synaptic strength. AMPAR expression can be regulated locally in dendrites by synaptic activity. The mechanisms of activity-dependent local regulation of AMPAR expression, however, remain unclear. Here, we tested whether microRNAs (miRNAs) are involved in N-methyl-D-aspartate (NMDA) receptor (NMDAR)-dependent AMPAR expression. We used the 3' untranslated region of Gria1, which encodes the AMPA receptor subunit GluA1, to pull down miRNAs binding to it and analyzed these miRNAs using next-generation deep sequencing. Among the identified miRNAs, miR-501-3p is also a computationally predicted Gria1-targeting miRNA. We confirmed that miR-501-3p targets Gria1 and regulates its expression under physiological conditions. The expression of miR-501-3p and GluA1, moreover, is inversely correlated during postnatal brain development. miR-501-3p expression is up-regulated locally in dendrites through the NMDAR subunit GluN2A, and this regulation is required for NMDA-induced suppression of GluA1 expression and long-lasting remodeling of dendritic spines. These findings elucidate a miRNA-mediated mechanism for activity-dependent, local regulation of AMPAR expression in dendrites.
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Affiliation(s)
- Zhonghua Hu
- Unit on Synapse Development and Plasticity, National Institute of Mental Health, and Genetics and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Jun Zhao
- Unit on Synapse Development and Plasticity, National Institute of Mental Health, and Genetics and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Tianyi Hu
- Unit on Synapse Development and Plasticity, National Institute of Mental Health, and Genetics and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Yan Luo
- Unit on Synapse Development and Plasticity, National Institute of Mental Health, and Genetics and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Jun Zhu
- Unit on Synapse Development and Plasticity, National Institute of Mental Health, and Genetics and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Zheng Li
- Unit on Synapse Development and Plasticity, National Institute of Mental Health, and Genetics and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
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110
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Synaptic strength is bidirectionally controlled by opposing activity-dependent regulation of Nedd4-1 and USP8. J Neurosci 2015; 34:16637-49. [PMID: 25505317 DOI: 10.1523/jneurosci.2452-14.2014] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The trafficking of AMPA receptors (AMPARs) to and from synapses is crucial for synaptic plasticity. Previous work has demonstrated that AMPARs undergo activity-dependent ubiquitination by the E3 ubiquitin ligase Nedd4-1, which promotes their internalization and degradation in lysosomes. Here, we define the molecular mechanisms involved in ubiquitination and deubiquitination of AMPARs. We report that Nedd4-1 is rapidly redistributed to dendritic spines in response to AMPAR activation and not in response to NMDA receptor (NMDAR) activation in cultured rat neurons. In contrast, NMDAR activation directly antagonizes Nedd4-1 function by promoting the deubiquitination of AMPARs. We show that NMDAR activation causes the rapid dephosphorylation and activation of the deubiquitinating enzyme (DUB) USP8. Surface AMPAR levels and synaptic strength are inversely regulated by Nedd4-1 and USP8. Strikingly, we show that homeostatic downscaling of synaptic strength is accompanied by an increase and decrease in Nedd4-1 and USP8 protein levels, respectively. Furthermore, we show that Nedd4-1 is required for homeostatic loss of surface AMPARs and downscaling of synaptic strength. This study provides the first mechanistic evidence for rapid and opposing activity-dependent control of a ubiquitin ligase and DUB at mammalian CNS synapses. We propose that the dynamic regulation of these opposing forces is critical in maintaining synapses and scaling them during homeostatic plasticity.
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111
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Mao LM, Xue B, Jin DZ, Wang JQ. Dynamic increases in AMPA receptor phosphorylation in the rat hippocampus in response to amphetamine. J Neurochem 2015; 133:795-805. [PMID: 25689263 DOI: 10.1111/jnc.13067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 01/30/2015] [Accepted: 02/04/2015] [Indexed: 01/12/2023]
Abstract
Increasing evidence supports the critical role of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors in psychostimulant action. These receptors are regulated via a phosphorylation-dependent mechanism in their trafficking, distribution, and function. The hippocampus is a brain structure important for learning and memory and is emerging as a critical site for processing psychostimulant effects. To determine whether the hippocampal pool of AMPA receptors is regulated by stimulants, we investigated and characterized the impact of amphetamine (AMPH) on phosphorylation of AMPA receptors in the adult rat hippocampus in vivo. We found that AMPH markedly increased phosphorylation of AMPA receptor GluA1 subunits at serine 845 (S845) in the hippocampus. The effect of AMPH was dose dependent. A single dose of AMPH induced a rapid and transient increase in S845 phosphorylation. Among different hippocampal subfields, AMPH primarily elevated S845 phosphorylation in the Cornu Ammonis area 1 and dentate gyrus. In contrast to S845, serine 831 phosphorylation of GluA1 and serine 880 phosphorylation of GluA2 were not altered by AMPH. In addition, surface expression of hippocampal GluA1 was up-regulated, while the amount of intracellular GluA1 fraction was concurrently reduced in response to AMPH. GluA2 protein levels in either the surface or intracellular pool were insensitive to AMPH. These data demonstrate that the AMPA receptor in the hippocampus is sensitive to dopamine stimulation. Acute AMPH administration induces dose-, time-, site-, and subunit-dependent phosphorylation of AMPA receptors and facilitates surface trafficking of GluA1 AMPA receptors in hippocampal neurons in vivo. Acute injection of amphetamine increased phosphorylation of α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor GluA1 subunits at a protein kinase A (PKA)-sensitive site (S845) in the rat hippocampus. This increase was dose- and time-dependent and correlated with an increase in surface GluA1 expression. Thus, amphetamine can upregulate GluA1 phosphorylation and surface trafficking of GluA1 in hippocampal neurons in vivo.
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Affiliation(s)
- Li-Min Mao
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, Missouri, USA
| | - Bing Xue
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, Missouri, USA
| | - Dao-Zhong Jin
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, Missouri, USA
| | - John Q Wang
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, Missouri, USA.,Department of Anesthesiology, School of Medicine, University of Missouri-Kansas City, Kansas City, Missouri, USA.,Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China
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112
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Scudder SL, Patrick GN. Synaptic structure and function are altered by the neddylation inhibitor MLN4924. Mol Cell Neurosci 2015; 65:52-7. [PMID: 25701678 DOI: 10.1016/j.mcn.2015.02.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 01/26/2015] [Accepted: 02/17/2015] [Indexed: 01/01/2023] Open
Abstract
The posttranslational modification of proteins by the ubiquitin-like small molecule NEDD8 has previously been shown to be vital in a number of cell signaling pathways. In particular, conjugation of NEDD8 (neddylation) serves to regulate protein ubiquitination through modifications to E3 ubiquitin ligases. Despite the prevalence of NEDD8 in neurons, very little work has been done to characterize the role of this modifier in these cells. Here, we use the recently developed NEDD8 Activating Enzyme (NAE) inhibitor MLN4924 and report evidence of a role for NEDD8 in regulating mammalian excitatory synapses. Application of this drug to dissociated rat hippocampal neurons caused reductions in synaptic strength, surface glutamate receptor levels, dendritic spine width, and spine density, suggesting that neddylation is involved in the maintenance of synapses.
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Affiliation(s)
- Samantha L Scudder
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, United States.
| | - Gentry N Patrick
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, United States.
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113
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Widagdo J, Chai YJ, Ridder MC, Chau YQ, Johnson RC, Sah P, Huganir RL, Anggono V. Activity-Dependent Ubiquitination of GluA1 and GluA2 Regulates AMPA Receptor Intracellular Sorting and Degradation. Cell Rep 2015; 10:783-795. [PMID: 25660027 PMCID: PMC4524782 DOI: 10.1016/j.celrep.2015.01.015] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 12/02/2014] [Accepted: 01/05/2015] [Indexed: 11/18/2022] Open
Abstract
AMPA receptors (AMPARs) have recently been shown to undergo post-translational ubiquitination in mammalian neurons. However, the underlying molecular mechanisms are poorly understood and remain controversial. Here, we report that all four AMPAR subunits (GluA1–4) are rapidly ubiquitinated upon brief application of AMPA or bicuculline in cultured neurons. This process is Ca2+ dependent and requires the activity of L-type voltage-gated Ca2+ channels and Ca2+/calmodulin-dependent kinase II. The ubiquitination of all subunits occurs exclusively on AMPARs located on the plasma membrane post-endocytosis. The sites of ubiquitination were mapped to Lys-868 in GluA1 and Lys-870/Lys-882 in GluA2 C-terminals. Mutation of these lysines did not affect basal surface expression or AMPA-induced internalization of GluA1 and GluA2 subunits. Instead, it reduced the intracellular trafficking of AMPARs to the late endosomes and thus protein degradation. These data indicate that ubiquitination is an important regulatory signal for controlling AMPAR function, which may be crucial for synaptic plasticity.
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Affiliation(s)
- Jocelyn Widagdo
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ye Jin Chai
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Margreet C Ridder
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Yu Qian Chau
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Richard C Johnson
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Pankaj Sah
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Richard L Huganir
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Victor Anggono
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, QLD 4072, Australia.
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Gratacòs-Batlle E, Yefimenko N, Cascos-García H, Soto D. AMPAR interacting protein CPT1C enhances surface expression of GluA1-containing receptors. Front Cell Neurosci 2015; 8:469. [PMID: 25698923 PMCID: PMC4313699 DOI: 10.3389/fncel.2014.00469] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 12/29/2014] [Indexed: 11/30/2022] Open
Abstract
AMPARs mediate the vast majority of fast excitatory synaptic transmission in the brain and their biophysical and trafficking properties depend on their subunit composition and on several posttranscriptional and posttranslational modifications. Additionally, in the brain AMPARs associate with auxiliary subunits, which modify the properties of the receptors. Despite the abundance of AMPAR partners, recent proteomic studies have revealed even more interacting proteins that could potentially be involved in AMPAR regulation. Amongst these, carnitine palmitoyltransferase 1C (CPT1C) has been demonstrated to form an integral part of native AMPAR complexes in brain tissue extracts. Thus, we aimed to investigate whether CPT1C might be able to modulate AMPAR function. Firstly, we confirmed that CPT1C is an interacting protein of AMPARs in heterologous expression systems. Secondly, CPT1C enhanced whole-cell currents of GluA1 homomeric and GluA1/GluA2 heteromeric receptors. However, CPT1C does not alter the biophysical properties of AMPARs and co-localization experiments revealed that AMPARs and CPT1C are not associated at the plasma membrane despite a strong level of co-localization at the intracellular level. We established that increased surface GluA1 receptor number was responsible for the enhanced AMPAR mediated currents in the presence of CPT1C. Additionally, we revealed that the palmitoylable residue C585 of GluA1 is important in the enhancement of AMPAR trafficking to the cell surface by CPT1C. Nevertheless, despite its potential as a depalmitoylating enzyme, CPT1C does not affect the palmitoylation state of GluA1. To sum up, this work suggests that CPT1C plays a role as a novel regulator of AMPAR surface expression in neurons. Fine modulation of AMPAR membrane trafficking is fundamental in normal synaptic activity and in plasticity processes and CPT1C is therefore a putative candidate to regulate neuronal AMPAR physiology.
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Affiliation(s)
- Esther Gratacòs-Batlle
- Laboratori de Neurobiologia, Area de Neurobiologia Cellular i Molecular, Institut d'Investigació Biomèdica de Bellvitge-IDIBELL L'Hospitalet de Llobregat, Spain ; Department of Pathology and Experimental Therapeutics, Faculty of Medicine, University of Barcelona L'Hospitalet de Llobregat, Spain
| | - Natalia Yefimenko
- Laboratori de Neurobiologia, Area de Neurobiologia Cellular i Molecular, Institut d'Investigació Biomèdica de Bellvitge-IDIBELL L'Hospitalet de Llobregat, Spain ; Department of Pathology and Experimental Therapeutics, Faculty of Medicine, University of Barcelona L'Hospitalet de Llobregat, Spain
| | - Helena Cascos-García
- Laboratori de Neurobiologia, Area de Neurobiologia Cellular i Molecular, Institut d'Investigació Biomèdica de Bellvitge-IDIBELL L'Hospitalet de Llobregat, Spain ; Department of Pathology and Experimental Therapeutics, Faculty of Medicine, University of Barcelona L'Hospitalet de Llobregat, Spain
| | - David Soto
- Laboratori de Neurobiologia, Area de Neurobiologia Cellular i Molecular, Institut d'Investigació Biomèdica de Bellvitge-IDIBELL L'Hospitalet de Llobregat, Spain ; Department of Pathology and Experimental Therapeutics, Faculty of Medicine, University of Barcelona L'Hospitalet de Llobregat, Spain
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115
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GluA1 phosphorylation contributes to postsynaptic amplification of neuropathic pain in the insular cortex. J Neurosci 2015; 34:13505-15. [PMID: 25274827 DOI: 10.1523/jneurosci.1431-14.2014] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Long-term potentiation of glutamatergic transmission has been observed after physiological learning or pathological injuries in different brain regions, including the spinal cord, hippocampus, amygdala, and cortices. The insular cortex is a key cortical region that plays important roles in aversive learning and neuropathic pain. However, little is known about whether excitatory transmission in the insular cortex undergoes plastic changes after peripheral nerve injury. Here, we found that peripheral nerve ligation triggered the enhancement of AMPA receptor (AMPAR)-mediated excitatory synaptic transmission in the insular cortex. The synaptic GluA1 subunit of AMPAR, but not the GluA2/3 subunit, was increased after nerve ligation. Genetic knock-in mice lacking phosphorylation of the Ser845 site, but not that of the Ser831 site, blocked the enhancement of the synaptic GluA1 subunit, indicating that GluA1 phosphorylation at the Ser845 site by protein kinase A (PKA) was critical for this upregulation after nerve injury. Furthermore, A-kinase anchoring protein 79/150 (AKAP79/150) and PKA were translocated to the synapses after nerve injury. Genetic deletion of adenylyl cyclase subtype 1 (AC1) prevented the translocation of AKAP79/150 and PKA, as well as the upregulation of synaptic GluA1-containing AMPARs. Pharmacological inhibition of calcium-permeable AMPAR function in the insular cortex reduced behavioral sensitization caused by nerve injury. Our results suggest that the expression of AMPARs is enhanced in the insular cortex after nerve injury by a pathway involving AC1, AKAP79/150, and PKA, and such enhancement may at least in part contribute to behavioral sensitization together with other cortical regions, such as the anterior cingulate and the prefrontal cortices.
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116
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Ménard C, Gaudreau P, Quirion R. Signaling pathways relevant to cognition-enhancing drug targets. Handb Exp Pharmacol 2015; 228:59-98. [PMID: 25977080 DOI: 10.1007/978-3-319-16522-6_3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Aging is generally associated with a certain cognitive decline. However, individual differences exist. While age-related memory deficits can be observed in humans and rodents in the absence of pathological conditions, some individuals maintain intact cognitive functions up to an advanced age. The mechanisms underlying learning and memory processes involve the recruitment of multiple signaling pathways and gene expression, leading to adaptative neuronal plasticity and long-lasting changes in brain circuitry. This chapter summarizes the current understanding of how these signaling cascades could be modulated by cognition-enhancing agents favoring memory formation and successful aging. It focuses on data obtained in rodents, particularly in the rat as it is the most common animal model studied in this field. First, we will discuss the role of the excitatory neurotransmitter glutamate and its receptors, downstream signaling effectors [e.g., calcium/calmodulin-dependent protein kinase II (CaMKII), protein kinase C (PKC), extracellular signal-regulated kinases (ERK), mammalian target of rapamycin (mTOR), cAMP response element-binding protein (CREB)], associated immediate early gene (e.g., Homer 1a, Arc and Zif268), and growth factors [insulin-like growth factors (IGFs) and brain-derived neurotrophic factor (BDNF)] in synaptic plasticity and memory formation. Second, the impact of the cholinergic system and related modulators on memory will be briefly reviewed. Finally, since dynorphin neuropeptides have recently been associated with memory impairments in aging, it is proposed as an attractive target to develop novel cognition-enhancing agents.
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Affiliation(s)
- Caroline Ménard
- Douglas Mental Health University Institute, McGill University, Perry Pavilion, 6875 LaSalle Boulevard, Montreal, QC, Canada, H4H 1R3
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117
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Lussier MP, Gu X, Lu W, Roche KW. Casein kinase 2 phosphorylates GluA1 and regulates its surface expression. Eur J Neurosci 2014; 39:1148-58. [PMID: 24712994 DOI: 10.1111/ejn.12494] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 12/17/2013] [Accepted: 01/02/2014] [Indexed: 11/30/2022]
Abstract
Controlling the density of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) at synapses is essential for regulating the strength of excitatory neurotransmission. In particular, the phosphorylation of AMPARs is important for defining both synaptic expression and intracellular routing of receptors. Phosphorylation is a post-translational modification known to regulate many cellular events and the C-termini of glutamate receptors are important targets. Recently, the first intracellular loop1 region of the GluA1 subunit of AMPARs was reported to regulate synaptic targeting through phosphorylation of S567 by Ca2+ /calmodulin-dependent protein kinase II (CaMKII). Intriguingly, the loop1 region of all four AMPAR subunits contains many putative phosphorylation sites (S/T/Y), leaving the possibility that other kinases may regulate AMPAR surface expression via phosphorylation of the loop regions. To explore this hypothesis, we used in vitro phosphorylation assays with a small panel of purified kinases and found that casein kinase 2 (CK2) phosphorylates the GluA1 and GluA2 loop1 regions, but not GluA3 or GluA4. Interestingly, when we reduced the endogenous expression of CK2 using a specific short hairpin RNA against the regulatory subunit CK2β, we detected a reduction of GluA1 surface expression, whereas GluA2 was unchanged. Furthermore, we identified S579 of GluA1 as a substrate of CK2, and the expression of GluA1 phosphodeficient mutants in hippocampal neurons displayed reduced surface expression. Therefore, our study identifies CK2 as a regulator of GluA1 surface expression by phosphorylating the intracellular loop1 region.
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Affiliation(s)
- Marc P Lussier
- Receptor Biology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
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118
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Huang WH, Chao HW, Tsai LY, Chung MH, Huang YS. Elevated activation of CaMKIIα in the CPEB3-knockout hippocampus impairs a specific form of NMDAR-dependent synaptic depotentiation. Front Cell Neurosci 2014; 8:367. [PMID: 25404896 PMCID: PMC4217494 DOI: 10.3389/fncel.2014.00367] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 10/16/2014] [Indexed: 02/05/2023] Open
Abstract
Cytoplasmic polyadenylation element binding protein 3 (CPEB3) is a sequence-specific RNA-binding protein that confines the strength of glutamatergic synapses by translationally downregulating the expression of multiple plasticity-related proteins (PRPs), including the N-methyl-D-aspartate receptor (NMDAR) and the postsynaptic density protein 95 (PSD95). CPEB3 knockout (KO) mice exhibit hippocampus-dependent abnormalities related not only to long-term spatial memory but also to the short-term acquisition and extinction of contextual fear memory. In this study, we identified a specific form of NMDAR-dependent synaptic depotentiation (DPT) that is impaired in the adult CPEB3 KO hippocampus. In parallel, cultured KO neurons also exhibited delayed morphological and biochemical responses under NMDA-induced chemical long-term depression (c-LTD). The c-LTD defects in the KO neurons include elevated activation of calcium/calmodulin-dependent protein kinase II alpha subunit (CaMKIIα), increased Ser831 phosphorylation of GluA1 and slow degradation of PSD95 and GluA1. Because transient pharmacological suppression of CaMKIIα activity during the DPT-initiating phase successfully reversed the LTP in the KO hippocampus, DPT and c-LTD in the two different systems shared common molecular defects due to the absence of CPEB3. Together, our results suggest that CPEB3 deficiency imbalances NMDAR-activated CaMKIIα signaling, which consequently fails to depress synaptic strength under certain stimulation conditions.
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Affiliation(s)
- Wen-Hsuan Huang
- Institute of Biomedical Sciences, Academia Sinica Taipei, Taiwan
| | - Hsu-Wen Chao
- Institute of Biomedical Sciences, Academia Sinica Taipei, Taiwan
| | - Li-Yun Tsai
- Institute of Biomedical Sciences, Academia Sinica Taipei, Taiwan
| | - Ming-Hung Chung
- Interdisciplinary Program of Life Sciences, National Tsing Hua University Hsinchu, Taiwan
| | - Yi-Shuian Huang
- Institute of Biomedical Sciences, Academia Sinica Taipei, Taiwan
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119
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Postsynaptic insertion of AMPA receptor onto cortical pyramidal neurons in the anterior cingulate cortex after peripheral nerve injury. Mol Brain 2014; 7:76. [PMID: 25359681 PMCID: PMC4221704 DOI: 10.1186/s13041-014-0076-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 10/21/2014] [Indexed: 12/12/2022] Open
Abstract
Long-term potentiation (LTP) is the key cellular mechanism for physiological learning and pathological chronic pain. Postsynaptic accumulation of AMPA receptor (AMPAR) GluA1 plays an important role for injury-related cortical LTP. However, there is no direct evidence for postsynaptic GluA1 insertion or accumulation after peripheral injury. Here we report nerve injury increased the postsynaptic expression of AMPAR GluA1 in pyramidal neurons in the layer V of the anterior cingulate cortex (ACC), including the corticospinal projecting neurons. Electrophysiological recordings show that potentiation of postsynaptic responses was reversed by Ca2+ permeable AMPAR antagonist NASPM. Finally, behavioral studies show that microinjection of NASPM into the ACC inhibited behavioral sensitization caused by nerve injury. Our findings provide direct evidence that peripheral nerve injury induces postsynaptic GluA1 accumulation in cingulate cortical neurons, and inhibits postsynaptic GluA1 accumulation which may serve as a novel target for treating neuropathic pain.
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120
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Regional Diversity and Developmental Dynamics of the AMPA-Receptor Proteome in the Mammalian Brain. Neuron 2014; 84:41-54. [DOI: 10.1016/j.neuron.2014.08.044] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2014] [Indexed: 12/20/2022]
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121
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Petrini EM, Barberis A. Diffusion dynamics of synaptic molecules during inhibitory postsynaptic plasticity. Front Cell Neurosci 2014; 8:300. [PMID: 25294987 PMCID: PMC4171989 DOI: 10.3389/fncel.2014.00300] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 09/05/2014] [Indexed: 12/24/2022] Open
Abstract
The plasticity of inhibitory transmission is expected to play a key role in the modulation of neuronal excitability and network function. Over the last two decades, the investigation of the determinants of inhibitory synaptic plasticity has allowed distinguishing presynaptic and postsynaptic mechanisms. While there has been a remarkable progress in the characterization of presynaptically-expressed plasticity of inhibition, the postsynaptic mechanisms of inhibitory long-term synaptic plasticity only begin to be unraveled. At postsynaptic level, the expression of inhibitory synaptic plasticity involves the rearrangement of the postsynaptic molecular components of the GABAergic synapse, including GABAA receptors, scaffold proteins and structural molecules. This implies a dynamic modulation of receptor intracellular trafficking and receptor surface lateral diffusion, along with regulation of the availability and distribution of scaffold proteins. This Review will focus on the mechanisms of the multifaceted molecular reorganization of the inhibitory synapse during postsynaptic plasticity, with special emphasis on the key role of protein dynamics to ensure prompt and reliable activity-dependent adjustments of synaptic strength.
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Affiliation(s)
- Enrica Maria Petrini
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia Genoa, Italy
| | - Andrea Barberis
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia Genoa, Italy
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122
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Abstract
Glutamate is the main excitatory neurotransmitter in the brain and ionotropic glutamate receptors mediate the majority of excitatory neurotransmission (Dingeldine et al. 1999). The high level of glutamatergic excitation allows the neonatal brain (the 2(nd) postnatal week in rat) to develop quickly but it also makes it highly prone to age-specific seizures that can cause lifelong neurological and cognitive disability (Haut et al. 2004). There are three types of ionotropic glutamate receptors (ligand-gated ion channels) named according to their prototypic agonists: N-methyl-D-aspartate (NMDA), 2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl) propanoic acid (AMPA) and kainate (KA). During early stages of postnatal development glutamate receptors of NMDA and AMPA type undergo intensive functional changes owing to modifications in their subunit composition (Carter et al. 1988, Watanabe et al. 1992, Monyer et al. 1994, Wenzel et al. 1997, Sun et al. 1998, Lilliu et al. 2001, Kumar et al. 2002, Matsuda et al. 2002, Wee et al. 2008, Henson et al. 2010, Pachernegg et al. 2012, Paoletti et al. 2013). Participation and role of these receptors in mechanisms of seizures and epilepsy became one of the main targets of intensive investigation (De Sarro et al. 2005, Di Maio et al. 2012, Rektor 2013). LiCl/Pilocarpine (LiCl/Pilo) induced status epilepticus is a model of severe seizures resulting in development temporal lobe epilepsy (TLE). This review will consider developmental changes and contribution of NMDA and AMPA receptors in LiCl/Pilo model of status epilepticus in immature rats.
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Affiliation(s)
- E Szczurowska
- Institute of Physiology AS CR, Prague, Czech Republic.
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123
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Multiple spatial and kinetic subpopulations of CaMKII in spines and dendrites as resolved by single-molecule tracking PALM. J Neurosci 2014; 34:7600-10. [PMID: 24872564 DOI: 10.1523/jneurosci.4364-13.2014] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII) is essential for synaptic plasticity underlying memory formation. Some functions of CaMKII are mediated by interactions with synaptic proteins, and activity-triggered translocation of CaMKII to synapses has been heavily studied. However, CaMKII actions away from the postsynaptic density (PSD) remain poorly understood, in part because of the difficulty in discerning where CaMKII binds in live cells. We used photoactivated localization microscopy (PALM) in rat hippocampal neurons to track single molecules of CaMKIIα, mapping its spatial and kinetic heterogeneity at high resolution. We found that CaMKIIα exhibits at least three kinetic subpopulations, even within individual spines. Latrunculin application or coexpression of CaMKIIβ carrying its actin-binding domain strongly modulated CaMKII diffusion, indicating that a major subpopulation is regulated by the actin cytoskeleton. CaMKII in spines was typically more slowly mobile than in dendrites, consistent with presence of a higher density of binding partners or obstacles. Importantly, NMDA receptor stimulation that triggered CaMKII activation prompted the immobilization and presumed binding of CaMKII in spines not only at PSDs but also at other points up to several hundred nanometers away, suggesting that activated kinase does not target only the PSD. Consistent with this, single endogenous activated CaMKII molecules detected via STORM immunocytochemistry were concentrated in spines both at the PSD and at points quite distant from the synapse. Together, these results indicate that CaMKII mobility within spines is determined by association with multiple interacting proteins, even outside the PSD, suggesting diverse mechanisms by which CaMKII may regulate synaptic transmission.
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124
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Mao LM, Jin DZ, Xue B, Chu XP, Wang JQ. Phosphorylation and regulation of glutamate receptors by CaMKII. SHENG LI XUE BAO : [ACTA PHYSIOLOGICA SINICA] 2014; 66:365-372. [PMID: 24964855 PMCID: PMC4435801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) is the most abundant kinase within excitatory synapses in the mammalian brain. It interacts with and phosphorylates a large number of synaptic proteins, including major ionotropic glutamate receptors (iGluRs) and group I metabotropic glutamate receptors (mGluRs), to constitutively and/or activity-dependently regulate trafficking, subsynaptic localization, and function of the receptors. Among iGluRs, the N-methyl-D-aspartate receptor (NMDAR) is a direct target of CaMKII. By directly binding to an intracellular C-terminal (CT) region of NMDAR GluN2B subunits, CaMKII phosphorylates a serine residue (S1303) in the GluN2B CT. CaMKII also phosphorylates a serine site (S831) in the CT of α-amino-3-hydroxy-5- methylisoxazole-4-propionic acid receptors. This phosphorylation enhances channel conductance and is critical for synaptic plasticity. In addition to iGluRs, CaMKII binds to the proximal CT region of mGluR1a, which enables the kinase to phosphorylate threonine 871. Agonist stimulation of mGluR1a triggers a CaMKII-mediated negative feedback to facilitate endocytosis and desensitization of the receptor. CaMKII also binds to the mGluR5 CT. This binding seems to anchor and accumulate inactive CaMKII at synaptic sites. Active CaMKII dissociates from mGluR5 and may then bind to adjacent GluN2B to mediate the mGluR5-NMDAR coupling. Together, glutamate receptors serve as direct substrates of CaMKII. By phosphorylating these receptors, CaMKII plays a central role in controlling the number and activity of the modified receptors and determining the strength of excitatory synaptic transmission.
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Affiliation(s)
- Li-Min Mao
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA.
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125
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Mao LM, Hastings JM, Fibuch EE, Wang JQ. Propofol selectively alters GluA1 AMPA receptor phosphorylation in the hippocampus but not prefrontal cortex in young and aged mice. Eur J Pharmacol 2014; 738:237-44. [PMID: 24907515 DOI: 10.1016/j.ejphar.2014.05.053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 05/27/2014] [Accepted: 05/28/2014] [Indexed: 10/25/2022]
Abstract
Propofol is a commonly used general anesthetic agent which has been previously shown to enhance the inhibitory GABAergic transmission in the central nervous system. In addition to the GABAergic element, the excitatory transmission may be another central molecular site impacted by propofol. Increasing evidence implies that the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor represents an excitatory amino acid receptor subtype subjected to the regulation by propofol. Indeed, in this study, we found that a single injection of propofol at an anesthetic dose increased AMPA receptor GluA1 subunit phosphorylation in young (2-3 months old) and aged (20-21 months old) mice in vivo. Propofol caused an increase in GluA1 phosphorylation in the hippocampus but not in the prefrontal cortex. The propofol effect was also site-selective as the drug elevated GluA1 phosphorylation at serine 831 (S831) but not serine 845. Interestingly, while propofol induced a moderate and transient increase in S831 phosphorylation in young mice, the drug caused a substantial and sustained S831 phosphorylation in aged animals. Total GluA1 abundance remained stable in the hippocampus and prefrontal cortex in both young and aged mice in response to propofol. These results provide evidence supporting the sensitivity of GluA1 AMPA receptors to propofol. A single dose of propofol was able to upregulate GluA1 phosphorylation in the confined hippocampus in an age-dependent manner.
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Affiliation(s)
- Li-Min Mao
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, MO 64108, USA
| | - James M Hastings
- Department of Anesthesiology, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Eugene E Fibuch
- Department of Anesthesiology, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - John Q Wang
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, MO 64108, USA; Department of Anesthesiology, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA.
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126
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Mechanisms of dopamine D1 receptor-mediated ERK1/2 activation in the parkinsonian striatum and their modulation by metabotropic glutamate receptor type 5. J Neurosci 2014; 34:4728-40. [PMID: 24672017 DOI: 10.1523/jneurosci.2702-13.2014] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In animal models of Parkinson's disease, striatal overactivation of ERK1/2 via dopamine (DA) D1 receptors is the hallmark of a supersensitive molecular response associated with dyskinetic behaviors. Here we investigate the pathways involved in D1 receptor-dependent ERK1/2 activation using acute striatal slices from rodents with unilateral 6-hydroxydopamine (6-OHDA) lesions. Application of the dopamine D1-like receptor agonist SKF38393 induced ERK1/2 phosphorylation and downstream signaling in the DA-denervated but not the intact striatum. This response was mediated through a canonical D1R/PKA/MEK1/2 pathway and independent of ionotropic glutamate receptors but blocked by antagonists of L-type calcium channels. Coapplication of an antagonist of metabotropic glutamate receptor type 5 (mGluR5) or its downstream signaling molecules (PLC, PKC, IP3 receptors) markedly attenuated SKF38393-induced ERK1/2 activation. The role of striatal mGluR5 in D1-dependent ERK1/2 activation was confirmed in vivo in 6-OHDA-lesioned animals treated systemically with SKF38393. In one experiment, local infusion of the mGluR5 antagonist MTEP in the DA-denervated rat striatum attenuated the activation of ERK1/2 signaling by SKF38393. In another experiment, 6-OHDA lesions were applied to transgenic mice with a cell-specific knockdown of mGluR5 in D1 receptor-expressing neurons. These mice showed a blunted striatal ERK1/2 activation in response to SFK38393 treatment. Our results reveal that D1-dependent ERK1/2 activation in the DA-denervated striatum depends on a complex interaction between PKA- and Ca(2+)-dependent signaling pathways that is critically modulated by striatal mGluR5.
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127
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Zhuravleva ZN, Khutsian SS. Structural signs of dynamic state of synaptic contacts between neurotransplant and brain. Bull Exp Biol Med 2014; 156:448-51. [PMID: 24771424 DOI: 10.1007/s10517-014-2371-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Indexed: 11/30/2022]
Abstract
We studied ultrastructure of synaptic connections between long-living dentate fascia transplants and somatosensory area of the neocortex in rats. Giant synaptic terminals of granular neurons upon contact with unusual neuronal targets in the neocortex reproduced their specific constitutive morphological features. At the same time, developing synapses with signs of active structural and metabolic reorganization were revealed. This is indicative of a dynamic state and instability of functional connections between the transplant and brain despite long time after transplantation.
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Affiliation(s)
- Z N Zhuravleva
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Puschino, Russia,
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128
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Ho VM, Dallalzadeh LO, Karathanasis N, Keles MF, Vangala S, Grogan T, Poirazi P, Martin KC. GluA2 mRNA distribution and regulation by miR-124 in hippocampal neurons. Mol Cell Neurosci 2014; 61:1-12. [PMID: 24784359 DOI: 10.1016/j.mcn.2014.04.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 03/17/2014] [Accepted: 04/12/2014] [Indexed: 11/19/2022] Open
Abstract
AMPA-type glutamate receptors mediate fast, excitatory neurotransmission in the brain, and their concentrations at synapses are important determinants of synaptic strength. We investigated the post-transcriptional regulation of GluA2, the calcium-impermeable AMPA receptor subunit, by examining the subcellular distribution of its mRNA and evaluating its translational regulation by microRNA in cultured mouse hippocampal neurons. Using computational approaches, we identified a conserved microRNA-124 (miR-124) binding site in the 3'UTR of GluA2 and demonstrated that miR-124 regulated the translation of GluA2 mRNA reporters in a sequence-specific manner in luciferase assays. While we hypothesized that this regulation might occur in dendrites, our biochemical and fluorescent in situ hybridization (FISH) data indicate that GluA2 mRNA does not localize to dendrites or synapses of mouse hippocampal neurons. In contrast, we detected significant concentrations of miR-124 in dendrites. Overexpression of miR-124 in dissociated neurons results in a 30% knockdown of GluA2 protein, as measured by immunoblot and quantitative immunocytochemistry, without producing any changes in GluA2 mRNA concentrations. While total GluA2 concentrations are reduced, we did not detect any changes in the concentration of synaptic GluA2. We conclude from these results that miR-124 interacts with GluA2 mRNA in the cell body to downregulate translation. Our data support a model in which GluA2 is translated in the cell body and subsequently transported to neuronal dendrites and synapses, and suggest that synaptic GluA2 concentrations are modified primarily by regulated protein trafficking rather than by regulated local translation.
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Affiliation(s)
- Victoria M Ho
- Interdepartmental Program for Neuroscience, University of California, Los Angeles, Los Angeles, CA 90095-1737, USA
| | - Liane O Dallalzadeh
- Interdepartmental Program for Neuroscience, University of California, Los Angeles, Los Angeles, CA 90095-1737, USA
| | - Nestoras Karathanasis
- Department of Biology, University of Crete, Heraklion, Crete, Greece; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece
| | - Mehmet F Keles
- Interdepartmental Program for Molecular, Cellular and Integrative Physiology, University of California, Los Angeles, Los Angeles, CA 90095-1737, USA
| | - Sitaram Vangala
- Department of Medicine Statistics Core, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Tristan Grogan
- Department of Medicine Statistics Core, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Panayiota Poirazi
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece
| | - Kelsey C Martin
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA 90095-1737, USA; Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, CA 90095-1737, USA; Integrated Center for Learning and Memory, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1737, USA.
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129
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Yang Y, Jin X, Jiang C. S-glutathionylation of ion channels: insights into the regulation of channel functions, thiol modification crosstalk, and mechanosensing. Antioxid Redox Signal 2014; 20:937-51. [PMID: 23834398 PMCID: PMC3924852 DOI: 10.1089/ars.2013.5483] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
SIGNIFICANCE Ion channels control membrane potential, cellular excitability, and Ca(++) signaling, all of which play essential roles in cellular functions. The regulation of ion channels enables cells to respond to changing environments, and post-translational modification (PTM) is one major regulation mechanism. RECENT ADVANCES Many PTMs (e.g., S-glutathionylation, S-nitrosylation, S-palmitoylation, S-sulfhydration, etc.) targeting the thiol group of cysteine residues have emerged to be essential for ion channels regulation under physiological and pathological conditions. CRITICAL ISSUES Under oxidative stress, S-glutathionylation could be a critical PTM that regulates many molecules. In this review, we discuss S-glutathionylation-mediated structural and functional changes of ion channels. Criteria for testing S-glutathionylation, methods and reagents used in ion channel S-glutathionylation studies, and thiol modification crosstalk, are also covered. Mechanotransduction, and S-glutathionylation of the mechanosensitive KATP channel, are discussed. FUTURE DIRECTIONS Further investigation of the ion channel S-glutathionylation, especially the physiological significance of S-glutathionylation and thiol modification crosstalk, could lead to a better understanding of the thiol modifications in general and the ramifications of such modifications on cellular functions and related diseases.
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Affiliation(s)
- Yang Yang
- 1 Department of Neurology, Yale University School of Medicine , New Haven, Connecticut
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130
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Uzunova G, Hollander E, Shepherd J. The role of ionotropic glutamate receptors in childhood neurodevelopmental disorders: autism spectrum disorders and fragile x syndrome. Curr Neuropharmacol 2014; 12:71-98. [PMID: 24533017 PMCID: PMC3915351 DOI: 10.2174/1570159x113116660046] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 08/20/2013] [Accepted: 09/25/2013] [Indexed: 12/20/2022] Open
Abstract
Autism spectrum disorder (ASD) and Fragile X syndrome (FXS) are relatively common childhood neurodevelopmental disorders with increasing incidence in recent years. They are currently accepted as disorders of the synapse with alterations in different forms of synaptic communication and neuronal network connectivity. The major excitatory neurotransmitter system in brain, the glutamatergic system, is implicated in learning and memory, synaptic plasticity, neuronal development. While much attention is attributed to the role of metabotropic glutamate receptors in ASD and FXS, studies indicate that the ionotropic glutamate receptors (iGluRs) and their regulatory proteins are also altered in several brain regions. Role of iGluRs in the neurobiology of ASD and FXS is supported by a weight of evidence that ranges from human genetics to in vitro cultured neurons. In this review we will discuss clinical, molecular, cellular and functional changes in NMDA, AMPA and kainate receptors and the synaptic proteins that regulate them in the context of ASD and FXS. We will also discuss the significance for the development of translational biomarkers and treatments for the core symptoms of ASD and FXS.
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Affiliation(s)
- Genoveva Uzunova
- Autism and Obsessive Compulsive Spectrum Program, Department of Psychiatry, Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th St, Bronx, New York 10467-2490
| | - Eric Hollander
- Autism and Obsessive Compulsive Spectrum Program, Department of Psychiatry, Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th St, Bronx, New York 10467-2490
| | - Jason Shepherd
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, 531A Wintrobe, 20N 1900 E, Salt Lake City, Utah 84132
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131
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Abstract
The study of synaptic plasticity and specifically LTP and LTD is one of the most active areas of research in neuroscience. In the last 25 years we have come a long way in our understanding of the mechanisms underlying synaptic plasticity. In 1988, AMPA and NMDA receptors were not even molecularly identified and we only had a simple model of the minimal requirements for the induction of plasticity. It is now clear that the modulation of the AMPA receptor function and membrane trafficking is critical for many forms of synaptic plasticity and a large number of proteins have been identified that regulate this complex process. Here we review the progress over the last two and a half decades and discuss the future challenges in the field.
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132
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Roles of subunit phosphorylation in regulating glutamate receptor function. Eur J Pharmacol 2013; 728:183-7. [PMID: 24291102 DOI: 10.1016/j.ejphar.2013.11.019] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 10/10/2013] [Accepted: 11/15/2013] [Indexed: 12/21/2022]
Abstract
Protein phosphorylation is an important mechanism for regulating ionotropic glutamate receptors (iGluRs). Early studies have established that major iGluR subtypes, including α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors and N-methyl-d-aspartate (NMDA) receptors, are subject to phosphorylation. Multiple serine, threonine, and tyrosine residues predominantly within the C-terminal regions of AMPA receptor and NMDA receptor subunits have been identified as sensitive phosphorylation sites. These distinct sites undergo either constitutive phosphorylation or activity-dependent phosphorylation induced by changing cellular and synaptic inputs. An increasing number of synapse-enriched protein kinases have been found to phosphorylate iGluRs The common kinases include protein kinase A, protein kinase C, Ca(2+)/calmodulin-dependent protein kinase II, Src/Fyn non-receptor tyrosine kinases, and cyclin dependent kinase-5. Regulated phosphorylation plays a well-documented role in modulating the biochemical, biophysical, and functional properties of the receptor. In the future, identifying the precise mechanisms how phosphorylation regulates iGluR activities and finding the link between iGluR phosphorylation and the pathogenesis of various brain diseases, including psychiatric and neurodegenerative diseases, chronic pain, stroke, Alzheimer's disease and substance addiction, will be hot topics and could contribute to the development of novel pharmacotherapies, by targeting the defined phosphorylation process, for suppressing iGluR-related disorders.
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133
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Sobolevsky AI. Structure and gating of tetrameric glutamate receptors. J Physiol 2013; 593:29-38. [PMID: 25556785 DOI: 10.1113/jphysiol.2013.264911] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Accepted: 10/25/2013] [Indexed: 11/08/2022] Open
Abstract
Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that open their ion-conducting pores in response to the binding of agonist glutamate. In recent years, significant progress has been achieved in studies of iGluRs by determining numerous structures of isolated water-soluble ligand-binding and amino-terminal domains, as well as solving the first crystal structure of the full-length AMPA receptor in the closed, antagonist-bound state. These structural data combined with electrophysiological and fluorescence recordings, biochemical experiments, mutagenesis and molecular dynamics simulations have greatly improved our understanding of iGluR assembly, activation and desensitization processes. This article reviews the recent structural and functional advances in the iGluR field and summarizes them in a simplified model of full-length iGluR gating.
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Affiliation(s)
- Alexander I Sobolevsky
- Department of Biochemistry & Molecular Biophysics, Columbia University, 650 West 168th Street, Black Bldg. 513, New York, NY, 10032, USA
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134
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Whitehead G, Jo J, Hogg EL, Piers T, Kim DH, Seaton G, Seok H, Bru-Mercier G, Son GH, Regan P, Hildebrandt L, Waite E, Kim BC, Kerrigan TL, Kim K, Whitcomb DJ, Collingridge GL, Lightman SL, Cho K. Acute stress causes rapid synaptic insertion of Ca2+ -permeable AMPA receptors to facilitate long-term potentiation in the hippocampus. ACTA ACUST UNITED AC 2013; 136:3753-65. [PMID: 24271563 PMCID: PMC3859225 DOI: 10.1093/brain/awt293] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The neuroendocrine response to episodes of acute stress is crucial for survival whereas the prolonged response to chronic stress can be detrimental. Learning and memory are particularly susceptible to stress with cognitive deficits being well characterized consequences of chronic stress. Although there is good evidence that acute stress can enhance cognitive performance, the mechanism(s) for this are unclear. We find that hippocampal slices, either prepared from rats following 30 min restraint stress or directly exposed to glucocorticoids, exhibit an N-methyl-d-aspartic acid receptor-independent form of long-term potentiation. We demonstrate that the mechanism involves an NMDA receptor and PKA-dependent insertion of Ca2+-permeable AMPA receptors into synapses. These then trigger the additional NMDA receptor-independent form of LTP during high frequency stimulation.
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Affiliation(s)
- Garry Whitehead
- 1 Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Medicine and Dentistry, University of Bristol, Whitson Street, Bristol BS1 3NY, UK
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135
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Camera D, Boase NA, Kumar S, Pow DV, Poronnik P. Subtle gait abnormalities in Nedd4 heterozygous mice. Behav Brain Res 2013; 260:15-24. [PMID: 24280120 DOI: 10.1016/j.bbr.2013.11.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 11/13/2013] [Accepted: 11/14/2013] [Indexed: 11/15/2022]
Abstract
Nedd4 is a widely expressed ubiquitin ligase that is necessary for normal neuronal development and function. However, largely due to the lethality of Nedd4 homozygous knockout mice, little is known about the physiological roles of Nedd4 in the adult brain. In this study we used Nedd4 heterozygous mice, which are viable and live to maturity, to assess for motor function and gait. Global motor function was not altered in these mice, a result consistent with the low level of Nedd4 expression observed in motor neurons of the spinal cord. However, Nedd4 heterozygous mice showed significant age-dependent changes in gait. The gait abnormalities included an overall extension of gait that was only evident in the 6 month old mice. We also observed distinct expression patterns of Nedd4, with pronounced staining in the Purkinje neurons of the cerebellum that are crucial for normal gait, and lower levels in other motor areas of the CNS. It has been recently shown that Nedd4 directly interacts with GluR1 containing AMPA receptors in an activity dependent manner to modulate receptor levels at the post-synaptic membrane. Using confocal immunohistochemistry, we found that there were subtle changes in GluR1 expression in 6 month old Nedd4 heterozygous mice. There appeared to be a redistribution of GluR1 into larger puncta in the molecular layer and in the membrane of the soma of the Purkinje neurons. This study is the first to show that a 50% reduction in Nedd4 levels is sufficient to produce significant gait defects in 6 month old mice. These defects may arise in part, from altered distribution of GluR1 in cerebellar neurons.
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Affiliation(s)
- Daria Camera
- Health Innovations Research Institute, School of Medical Science, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia
| | - Natasha A Boase
- Centre for Cancer Biology, SA Pathology, Frome Road, Adelaide, SA 5000, Australia
| | - Sharad Kumar
- Centre for Cancer Biology, SA Pathology, Frome Road, Adelaide, SA 5000, Australia; Department of Medicine, University of Adelaide, North Terrace, Adelaide, SA 5000, Australia; Division of Health Science, University of South Australia, North Terrace, Adelaide, SA 5000, Australia
| | - David V Pow
- Health Innovations Research Institute, School of Medical Science, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia
| | - Philip Poronnik
- Health Innovations Research Institute, School of Medical Science, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia; School of Medical Sciences and The Bosch Institute, The University of Sydney, Camperdown, NSW 2006, Australia.
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136
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Brockie PJ, Jensen M, Mellem JE, Jensen E, Yamasaki T, Wang R, Maxfield D, Thacker C, Hoerndli F, Dunn PJ, Tomita S, Madsen DM, Maricq AV. Cornichons control ER export of AMPA receptors to regulate synaptic excitability. Neuron 2013; 80:129-42. [PMID: 24094107 DOI: 10.1016/j.neuron.2013.07.028] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/16/2013] [Indexed: 12/16/2022]
Abstract
The strength of synaptic communication at central synapses depends on the number of ionotropic glutamate receptors, particularly the class gated by the agonist AMPA (AMPARs). Cornichon proteins, evolutionarily conserved endoplasmic reticulum cargo adaptors, modify the properties of vertebrate AMPARs when coexpressed in heterologous cells. However, the contribution of cornichons to behavior and in vivo nervous system function has yet to be determined. Here, we take a genetic approach to these questions by studying CNI-1--the sole cornichon homolog in C. elegans. cni-1 mutants hyperreverse, a phenotype associated with increased glutamatergic synaptic transmission. Consistent with this behavior, we find larger glutamate-gated currents in cni-1 mutants with a corresponding increase in AMPAR number. Furthermore, we observe opposite phenotypes in transgenic worms that overexpress CNI-1 or vertebrate homologs. In reconstitution studies, we provide support for an evolutionarily conserved role for cornichons in regulating the export of vertebrate and invertebrate AMPARs.
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Affiliation(s)
- Penelope J Brockie
- Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA
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137
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Henley JM, Wilkinson KA. AMPA receptor trafficking and the mechanisms underlying synaptic plasticity and cognitive aging. DIALOGUES IN CLINICAL NEUROSCIENCE 2013. [PMID: 23576886 PMCID: PMC3622464 DOI: 10.31887/dcns.2013.15.1/jhenley] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Even in healthy individuals there is an inexorable agerelated decline in cognitive function. This is due, in large part, to reduced synaptic plasticity caused by changes in the molecular composition of the postsynaptic membrane. AMPA receptors (AMPARs) are glutamate-gated cation channels that mediate the overwhelming majority of fast excitatory transmission in the brain. Changes in AMPAR number and/or function are a core feature of synaptic plasticity and age-related cognitive decline, AMPARs are highly dynamic proteins that are subject to highly controlled trafficking, recycling, and/or degradation and replacement. This active regulation of AMPAR synthesis, targeting, synaptic dwell time, and degradation is fundamentally important for memory formation and storage. Further, aberrant AMPAR trafficking and consequent detrimental changes in synapses are strongly implicated in many brain diseases, which represent a vast social and economic burden. The purpose of this article is to provide an overview of the molecular and cellular AMPA receptor trafficking events that control synaptic responsiveness and plasticity, and highlight what is known currently known about how these processes change with age and disease.
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Affiliation(s)
- Jeremy M Henley
- School of Biochemistry, MRC Centre for Synaptic Plasticity, University of Bristol, Bristol, UK.
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138
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Wang Y, Lei Y, Fang L, Mu Y, Wu J, Zhang X. Roles of phosphotase 2A in nociceptive signal processing. Mol Pain 2013; 9:46. [PMID: 24010880 PMCID: PMC3844580 DOI: 10.1186/1744-8069-9-46] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Accepted: 08/30/2013] [Indexed: 12/23/2022] Open
Abstract
Multiple protein kinases affect the responses of dorsal horn neurons through phosphorylation of synaptic receptors and proteins involved in intracellular signal transduction pathways, and the consequences of this modulation may be spinal central sensitization. In contrast, the phosphatases catalyze an opposing reaction of de-phosphorylation, which may also modulate the functions of crucial proteins in signaling nociception. This is an important mechanism in the regulation of intracellular signal transduction pathways in nociceptive neurons. Accumulated evidence has shown that phosphatase 2A (PP2A), a serine/threonine specific phosphatase, is implicated in synaptic plasticity of the central nervous system and central sensitization of nociception. Therefore, targeting protein phosphotase 2A may provide an effective and novel strategy for the treatment of clinical pain. This review will characterize the structure and functional regulation of neuronal PP2A and bring together recent advances on the modulation of PP2A in targeted downstream substrates and relevant multiple nociceptive signaling molecules.
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Affiliation(s)
- Yun Wang
- Department of Anesthesiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China.
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139
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Rajasekaran K, Joshi S, Kozhemyakin M, Todorovic MS, Kowalski S, Balint C, Kapur J. Receptor trafficking hypothesis revisited: Plasticity of AMPA receptors during established status epilepticus. Epilepsia 2013; 54 Suppl 6:14-6. [DOI: 10.1111/epi.12266] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Karthik Rajasekaran
- Department of Neurology; University of Virginia; Health Sciences Center; Charlottesville; Virginia; U.S.A
| | - Suchitra Joshi
- Department of Neurology; University of Virginia; Health Sciences Center; Charlottesville; Virginia; U.S.A
| | - Maxim Kozhemyakin
- Department of Neurology; University of Virginia; Health Sciences Center; Charlottesville; Virginia; U.S.A
| | - Marko S. Todorovic
- Department of Neurology; University of Virginia; Health Sciences Center; Charlottesville; Virginia; U.S.A
| | - Samuel Kowalski
- Department of Neurology; University of Virginia; Health Sciences Center; Charlottesville; Virginia; U.S.A
| | - Corinne Balint
- Department of Neurology; University of Virginia; Health Sciences Center; Charlottesville; Virginia; U.S.A
| | - Jaideep Kapur
- Department of Neurology; University of Virginia; Health Sciences Center; Charlottesville; Virginia; U.S.A
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140
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Thomas GM, Hayashi T. Smarter neuronal signaling complexes from existing components: How regulatory modifications were acquired during animal evolution. Bioessays 2013; 35:929-39. [DOI: 10.1002/bies.201300076] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Gareth M. Thomas
- Shriners Hospitals Pediatric Research Center and Department of Anatomy and Cell Biology; Temple University Medical School; Philadelphia PA USA
| | - Takashi Hayashi
- Department of Molecular Neurobiology and Pharmacology; Graduate School of Medicine; The University of Tokyo; Bunkyo-ku Tokyo Japan
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141
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A eukaryotic specific transmembrane segment is required for tetramerization in AMPA receptors. J Neurosci 2013; 33:9840-5. [PMID: 23739980 DOI: 10.1523/jneurosci.2626-12.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Most fast excitatory synaptic transmission in the nervous system is mediated by glutamate acting through ionotropic glutamate receptors (iGluRs). iGluRs (AMPA, kainate, and NMDA receptor subtypes) are tetrameric assemblies, formed as a dimer of dimers. Still, the mechanism underlying tetramerization--the necessary step for the formation of functional receptors that can be inserted into the plasma membrane--is unknown. All eukaryotic compared to prokaryotic iGluR subunits have an additional transmembrane segment, the M4 segment, which positions the physiologically critical C-terminal domain on the cytoplasmic side of the membrane. AMPA receptor (AMPAR) subunits lacking M4 do not express on the plasma membrane. Here, we show that these constructs are retained in the endoplasmic reticulum, the major cellular compartment mediating protein oligomerization. Using approaches to assay the native oligomeric state of AMPAR subunits, we find that subunits lacking M4 or containing single amino acid substitutions along an "interacting" face of the M4 helix that block surface expression no longer tetramerize in either homomeric or heteromeric assemblies. In contrast, subunit dimerization appears to be largely intact. These experiments define the M4 segment as a unique functional unit in AMPARs that is required for the critical dimer-to-tetramer transition.
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142
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Stress and excitatory synapses: from health to disease. Neuroscience 2013; 248:626-36. [PMID: 23727506 DOI: 10.1016/j.neuroscience.2013.05.043] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 05/01/2013] [Accepted: 05/21/2013] [Indexed: 01/20/2023]
Abstract
Individuals are exposed to stressful events in their daily life. The effects of stress on brain function ranges from highly adaptive to increasing the risk to develop psychopathology. For example, stressful experiences are remembered well which can be seen as a highly appropriate behavioral adaptation. On the other hand, stress is an important risk factor, in susceptible individuals, for depression and anxiety. An important question that remains to be addressed is how stress regulates brain function and what determines the threshold between adaptive and maladaptive responses. Excitatory synapses play a crucial role in synaptic transmission, synaptic plasticity and behavioral adaptation. In this review we discuss how brief and prolonged exposure to stress, in adulthood and early life, regulate the function of these synapses, and how these effects may contribute to behavioral adaptation and psychopathology.
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143
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Abstract
The mechanisms by which natural rewards such as sugar affect synaptic transmission and behavior are largely unexplored. Here, we investigate regulation of nucleus accumbens synapses by sucrose intake. Previous studies have shown that AMPA receptor (AMPAR) trafficking is a major mechanism for regulating synaptic strength, and that in vitro, trafficking of AMPARs containing the GluA1 subunit takes place by a two-step mechanism involving extrasynaptic and then synaptic receptor transport. We report that in rat, repeated daily ingestion of a 25% sucrose solution transiently elevated spontaneous locomotion and potentiated accumbens core synapses through incorporation of Ca(2+)-permeable AMPA receptors (CPARs), which are GluA1-containing, GluA2-lacking AMPARs. Electrophysiological, biochemical, and quantitative electron microscopy studies revealed that sucrose training (7 d) induced a stable (>24 h) intraspinous GluA1 population, and that in these rats a single sucrose stimulus rapidly (5 min) but transiently (<24 h) elevated GluA1 at extrasynaptic sites. CPARs and dopamine D1 receptors were required in vivo for elevated locomotion after sucrose ingestion. Significantly, a 7 d protocol of daily ingestion of a 3% solution of saccharin, a noncaloric sweetener, induced synaptic GluA1 similarly to 25% sucrose ingestion. These findings identify multistep GluA1 trafficking, previously described in vitro, as a mechanism for acute regulation of synaptic transmission in vivo by a natural orosensory reward. Trafficking is stimulated by a chemosensory pathway that is not dependent on the caloric value of sucrose.
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144
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Wen S, Schroeter A, Klöcker N. Synaptic plasticity in hepatic encephalopathy - a molecular perspective. Arch Biochem Biophys 2013; 536:183-8. [PMID: 23624147 DOI: 10.1016/j.abb.2013.04.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 04/13/2013] [Accepted: 04/15/2013] [Indexed: 01/04/2023]
Abstract
Hepatic encephalopathy (HE)(1) is a common neuropsychiatric complication of both acute and chronic liver disease. Clinical symptoms may include motor disturbances and cognitive dysfunction. Available animal models of HE mimic the deficits in cognitive performance including the impaired ability to learn and memorize information. This review explores the question how HE might affect cognitive functions at molecular levels. Both acute and chronic models of HE constrain the plasticity of glutamatergic neurotransmission. Thus, long-lasting activity-dependent changes in synaptic efficiency, known as long-term potentiation (LTP) and long-term depression (LTD) are significantly impeded. We discuss molecules and signal transduction pathways of LTP and LTD that are targeted by experimental HE, with a focus on ionotropic glutamate receptors of the AMPA-subtype. Finally, a novel strategy of functional proteomic analysis is presented, which, if applied differentially, may provide molecular insight into disease-related dysfunction of membrane protein complexes, i.e. disturbed ionotropic glutamate receptor signaling in HE.
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Affiliation(s)
- Shuping Wen
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf D-40225 Düsseldorf, Germany
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145
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Blaskovic S, Blanc M, van der Goot FG. What does S-palmitoylation do to membrane proteins? FEBS J 2013; 280:2766-74. [PMID: 23551889 DOI: 10.1111/febs.12263] [Citation(s) in RCA: 182] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 03/20/2013] [Accepted: 03/25/2013] [Indexed: 12/19/2022]
Abstract
S-palmitoylation is post-translational modification, which consists in the addition of a C16 acyl chain to cytosolic cysteines and which is unique amongst lipid modifications in that it is reversible. It can thus, like phosphorylation or ubiquitination, act as a switch. While palmitoylation of soluble proteins allows them to interact with membranes, the consequences of palmitoylation for transmembrane proteins are more enigmatic. We briefly review the current knowledge regarding the enzymes responsible for palmitate addition and removal. We then describe various observed consequences of membrane protein palmitoylation. We propose that the direct effects of palmitoylation on transmembrane proteins, however, might be limited to four non-mutually exclusive mechanistic consequences: alterations in the conformation of transmembrane domains, association with specific membrane domains, controlled interactions with other proteins and controlled interplay with other post-translational modifications.
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Affiliation(s)
- Sanja Blaskovic
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Switzerland
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146
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Bats C, Farrant M, Cull-Candy SG. A role of TARPs in the expression and plasticity of calcium-permeable AMPARs: evidence from cerebellar neurons and glia. Neuropharmacology 2013; 74:76-85. [PMID: 23583927 PMCID: PMC3751754 DOI: 10.1016/j.neuropharm.2013.03.037] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/21/2013] [Accepted: 03/28/2013] [Indexed: 02/04/2023]
Abstract
The inclusion of GluA2 subunits has a profound impact on the channel properties of AMPA receptors (AMPARs), in particular rendering them impermeable to calcium. While GluA2-containing AMPARs are the most abundant in the central nervous system, GluA2-lacking calcium-permeable AMPARs are also expressed in wide variety of neurons and glia. Accumulating evidence suggests that the dynamic control of the GluA2 content of AMPARs plays a critical role in development, synaptic plasticity, and diverse neurological conditions ranging from ischemia-induced brain damage to drug addiction. It is thus important to understand the molecular mechanisms involved in regulating the balance of AMPAR subtypes, particularly the role of their co-assembled auxiliary subunits. The discovery of transmembrane AMPAR regulatory proteins (TARPs), initially within the cerebellum, has transformed the field of AMPAR research. It is now clear that these auxiliary subunits play a key role in multiple aspects of AMPAR trafficking and function in the brain. Yet, their precise role in AMPAR subtype-specific regulation has only recently received particular attention. Here we review recent findings on the differential regulation of calcium-permeable (CP-) and -impermeable (CI-) AMPARs in cerebellar neurons and glial cells, and discuss the critical involvement of TARPs in this process. This article is part of the Special Issue entitled ‘Glutamate Receptor-Dependent Synaptic Plasticity’. Calcium-permeable AMPARs are present in various cerebellar neurons and glial cells. The contribution of calcium-permeable AMPARs to transmission is dynamically regulated. TARPs influence the relative expression of AMPAR subtypes. Evidence suggests that TARPs play a role in calcium-permeable AMPAR plasticity.
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Affiliation(s)
- Cécile Bats
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
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147
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Middei S, Houeland G, Cavallucci V, Ammassari-Teule M, D'Amelio M, Marie H. CREB is necessary for synaptic maintenance and learning-induced changes of the ampa receptor GluA1 subunit. Hippocampus 2013; 23:488-99. [DOI: 10.1002/hipo.22108] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2013] [Indexed: 02/05/2023]
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148
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Henley JM, Wilkinson KA. AMPA receptor trafficking and the mechanisms underlying synaptic plasticity and cognitive aging. DIALOGUES IN CLINICAL NEUROSCIENCE 2013; 15:11-27. [PMID: 23576886 PMCID: PMC3622464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Even in healthy individuals there is an inexorable agerelated decline in cognitive function. This is due, in large part, to reduced synaptic plasticity caused by changes in the molecular composition of the postsynaptic membrane. AMPA receptors (AMPARs) are glutamate-gated cation channels that mediate the overwhelming majority of fast excitatory transmission in the brain. Changes in AMPAR number and/or function are a core feature of synaptic plasticity and age-related cognitive decline, AMPARs are highly dynamic proteins that are subject to highly controlled trafficking, recycling, and/or degradation and replacement. This active regulation of AMPAR synthesis, targeting, synaptic dwell time, and degradation is fundamentally important for memory formation and storage. Further, aberrant AMPAR trafficking and consequent detrimental changes in synapses are strongly implicated in many brain diseases, which represent a vast social and economic burden. The purpose of this article is to provide an overview of the molecular and cellular AMPA receptor trafficking events that control synaptic responsiveness and plasticity, and highlight what is known currently known about how these processes change with age and disease.
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Affiliation(s)
- Jeremy M Henley
- School of Biochemistry, MRC Centre for Synaptic Plasticity, University of Bristol, Bristol, UK.
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149
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Savina TA, Shchipakina TG, Levin SG, Godukhin OV. Interleukin-10 prevents the hypoxia-induced decreases in expressions of AMPA receptor subunit GluA1 and alpha subunit of Ca2+/calmodulin-dependent protein kinase II in hippocampal neurons. Neurosci Lett 2013. [DOI: 10.1016/j.neulet.2012.11.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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150
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Jaafari N, Konopacki FA, Owen TF, Kantamneni S, Rubin P, Craig TJ, Wilkinson KA, Henley JM. SUMOylation is required for glycine-induced increases in AMPA receptor surface expression (ChemLTP) in hippocampal neurons. PLoS One 2013; 8:e52345. [PMID: 23326329 PMCID: PMC3543417 DOI: 10.1371/journal.pone.0052345] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Accepted: 11/16/2012] [Indexed: 11/18/2022] Open
Abstract
Multiple pathways participate in the AMPA receptor trafficking that underlies long-term potentiation (LTP) of synaptic transmission. Here we demonstrate that protein SUMOylation is required for insertion of the GluA1 AMPAR subunit following transient glycine-evoked increase in AMPA receptor surface expression (ChemLTP) in dispersed neuronal cultures. ChemLTP increases co-localisation of SUMO-1 and the SUMO conjugating enzyme Ubc9 and with PSD95 consistent with the recruitment of SUMOylated proteins to dendritic spines. In addition, we show that ChemLTP increases dendritic levels of SUMO-1 and Ubc9 mRNA. Consistent with activity dependent translocation of these mRNAs to sites near synapses, levels of the mRNA binding and dendritic transport protein CPEB are also increased by ChemLTP. Importantly, reducing the extent of substrate protein SUMOylation by overexpressing the deSUMOylating enzyme SENP-1 or inhibiting SUMOylation by expressing dominant negative Ubc9 prevent the ChemLTP-induced increase in both AMPAR surface expression and dendritic SUMO-1 mRNA. Taken together these data demonstrate that SUMOylation of synaptic protein(s) involved in AMPA receptor trafficking is necessary for activity-dependent increases in AMPAR surface expression.
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Affiliation(s)
- Nadia Jaafari
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | | | - Thomas F. Owen
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | | | - Philip Rubin
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Tim J. Craig
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | | | - Jeremy M. Henley
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
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