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Porcher C, Hatchett C, Longbottom RE, McAinch K, Sihra TS, Moss SJ, Thomson AM, Jovanovic JN. Positive feedback regulation between gamma-aminobutyric acid type A (GABA(A)) receptor signaling and brain-derived neurotrophic factor (BDNF) release in developing neurons. J Biol Chem 2011; 286:21667-77. [PMID: 21474450 DOI: 10.1074/jbc.m110.201582] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
During the early development of the nervous system, γ-aminobutyric acid (GABA) type A receptor (GABA(A)R)-mediated signaling parallels the neurotrophin/tropomyosin-related kinase (Trk)-dependent signaling in controlling a number of processes from cell proliferation and migration, via dendritic and axonal outgrowth, to synapse formation and plasticity. Here we present the first evidence that these two signaling systems regulate each other through a complex positive feedback mechanism. We first demonstrate that GABA(A)R activation leads to an increase in the cell surface expression of these receptors in cultured embryonic cerebrocortical neurons, specifically at the stage when this activity causes depolarization of the plasma membrane and Ca(2+) influx through L-type voltage-gated Ca(2+) channels. We further demonstrate that GABA(A)R activity triggers release of the brain-derived neurotrophic factor (BDNF), which, in turn by activating TrkB receptors, mediates the observed increase in cell surface expression of GABA(A)Rs. This BDNF/TrkB-dependent increase in surface levels of GABA(A)Rs requires the activity of phosphoinositide 3-kinase (PI3K) and protein kinase C (PKC) and does not involve the extracellular signal-regulated kinase (ERK) 1/2 activity. The increase in GABA(A)R surface levels occurs due to an inhibition of the receptor endocytosis by BDNF, whereas the receptor reinsertion into the plasma membrane remains unaltered. Thus, GABA(A)R activity is a potent regulator of the BDNF release during neuronal development, and at the same time, it is strongly enhanced by the activity of the BDNF/TrkB/PI3K/PKC signaling pathway.
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Affiliation(s)
- Christophe Porcher
- Institut de Neurobiologie de la Méditerranée, INSERM Unité 901 and Université de La Méditerranée, 13273 Marseille Cedex 09, France
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52
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Kuczewski N, Fuchs C, Ferrand N, Jovanovic JN, Gaiarsa JL, Porcher C. Mechanism of GABAB receptor-induced BDNF secretion and promotion of GABAA receptor membrane expression. J Neurochem 2011; 118:533-45. [PMID: 21255015 DOI: 10.1111/j.1471-4159.2011.07192.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Recent studies have shown that GABA(B) receptors play more than a classical inhibitory role and can function as an important synaptic maturation signal early in life. In a previous study, we reported that GABA(B) receptor activation triggers secretion of brain-derived neurotrophic factor (BDNF) and promotes the functional maturation of GABAergic synapses in the developing rat hippocampus. To identify the signalling pathway linking GABA(B) receptor activation to BDNF secretion in these cells, we have now used the phosphorylated form of the cAMP response element-binding protein as a biological sensor for endogenous BDNF release. In the present study, we show that GABA(B) receptor-induced secretion of BDNF relies on the activation of phospholipase C, followed by the formation of diacylglycerol, activation of protein kinase C, and the opening of L-type voltage-dependent Ca(2+) channels. We further show that once released by GABA(B) receptor activation, BDNF increases the membrane expression of β(2/3) -containing GABA(A) receptors in neuronal cultures. These results reveal a novel function of GABA(B) receptors in regulating the expression of GABA(A) receptor through BDNF-tropomyosin-related kinase B receptor dependent signalling pathway.
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Affiliation(s)
- Nicola Kuczewski
- INSERM (Institut National de la Santé et de la Recherche Médicale) Unité 901, Marseille, France.
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53
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Tomiyama K, Song L, Kobayashi M, Kinsella A, Kanematsu T, Hirata M, Koshikawa N, Waddington JL. Orofacial movements in phospholipase C-related catalytically inactive protein-1/2 double knockout mice: Effect of the GABAergic agent diazepam and the D(1) dopamine receptor agonist SKF 83959. Synapse 2010; 64:714-20. [PMID: 20340178 DOI: 10.1002/syn.20798] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Orofacial movements are regulated by D(1)-like dopamine receptors interacting with additional mechanisms. Phospholipase C-related catalytically inactive protein (PRIP) regulates cell surface expression of GABA(A) receptors containing a gamma2 subunit. Mutant mice with double knockout of PRIP-1 and PRIP-2 were used to investigate aspects of GABAergic regulation of orofacial movements and interactions with D(1) mechanisms. Vertical jaw movements, tongue protrusions and movements of the head and vibrissae were reduced in PRIP-1/2 double knockouts. The GABA(A)ergic agent diazepam reduced movements of the head and vibrissae; these effects were unaltered in PRIP-1/2 double knockouts. The D(1)-like agonist SKF 83959 induced vertical jaw movements, incisor chattering, and movements of the head and vibrissae that were unaltered in PRIP-1/2 double knockouts. However, SKF 83959-induced tongue protrusions were reduced in PRIP-1/2 double knockouts. PRIP-mediated regulation of GABA(A)ergic receptor mechanisms influences topographically distinct aspects of orofacial movement and interacts with D(1) receptor systems.
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Affiliation(s)
- Katsunori Tomiyama
- Advanced Research Institute for the Sciences and Humanities, Nihon University, Tokyo 102, Japan.
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54
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Lu H, Cheng PL, Lim BK, Khoshnevisrad N, Poo MM. Elevated BDNF after cocaine withdrawal facilitates LTP in medial prefrontal cortex by suppressing GABA inhibition. Neuron 2010; 67:821-33. [PMID: 20826313 DOI: 10.1016/j.neuron.2010.08.012] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2010] [Indexed: 11/26/2022]
Abstract
Medial prefrontal cortex (mPFC) is known to be involved in relapse after cocaine withdrawal, but the underlying cellular mechanism remains largely unknown. Here, we report that after terminating repeated cocaine exposure in rats, a gradual increase in the expression of brain-derived neurotrophic factor (BDNF) in the mPFC facilitates activity-induced long-term potentiation (LTP) of excitatory synapses on layer V pyramidal neurons. This enhanced synaptic plasticity could be attributed to BDNF-induced suppression of GABAergic inhibition in the mPFC by reducing the surface expression of GABA(A) receptors. The BDNF effect was mediated by BDNF-TrkB-phosphatase 2A signaling pathway. Downregulating TrkB expression bilaterally in the mPFC reduced the locomotor hypersensitivity to cocaine 8 days after cocaine withdrawal. Thus, elevated BDNF expression after cocaine withdrawal sensitizes the excitatory synapses in the mPFC to undergo activity-induced persistent potentiation that may contribute to cue-induced drug craving and drug-seeking behavior.
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Affiliation(s)
- Hui Lu
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
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55
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Smith KR, Kittler JT. The cell biology of synaptic inhibition in health and disease. Curr Opin Neurobiol 2010; 20:550-6. [PMID: 20650630 DOI: 10.1016/j.conb.2010.06.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Revised: 06/08/2010] [Accepted: 06/10/2010] [Indexed: 11/24/2022]
Abstract
Fast synaptic inhibition is largely mediated by GABA(A) receptors (GABA(A)Rs), ligand-gated chloride channels that play an essential role in the control of cell and network activity in the brain. Recent work has demonstrated that the delivery, number and stability of GABA(A)Rs at inhibitory synapses play a key role in the dynamic regulation of inhibitory synaptic efficacy and plasticity. The regulatory pathways essential for the fine-tuning of synaptic inhibition have also emerged as key sites of vulnerability during pathological changes in cell excitability in disease states.
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Affiliation(s)
- Katharine R Smith
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
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56
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Thomson AM, Jovanovic JN. Mechanisms underlying synapse-specific clustering of GABA(A) receptors. Eur J Neurosci 2010; 31:2193-203. [PMID: 20550567 DOI: 10.1111/j.1460-9568.2010.07252.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A principle that arises from a body of previous work is that each presynaptic terminal recognises its postsynaptic partner and that each postsynaptic site recognises the origin of the synaptic bouton innervating it. In response, the presynaptic terminal sequesters the proteins whose interactions result in the dynamic transmitter release pattern and chemical modulation appropriate for that connection. In parallel, the postsynaptic site sequesters, inserts or captures the receptors and postsynaptic density proteins appropriate for that type of synapse. The focus of this review is the selective clustering of GABA(A) receptors (GABA(A)R) at synapses made by each class of inhibitory interneurone. This provides a system in which the mechanisms underlying transynaptic recognition can be explored. There are many synaptic proteins, often with several isoforms created by post-translational modifications. Complex cascades of interactions between these proteins, on either side of the synaptic cleft, are essential for normal function, normal transmitter release and postsynaptic responsiveness. Interactions between presynaptic and postsynaptic proteins that have binding domains in the synaptic cleft are proposed here to result in a local cleft structure that captures and stabilises only the appropriate subtype of GABA(A)Rs, allowing others to drift away from that synapse, either to be captured by another synapse, or internalised.
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Affiliation(s)
- Alex M Thomson
- The School of Pharmacy, London University, 29-39 Brunswick Square, London WC1N 1AX, UK.
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57
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Abstract
Dopaminergic projections to the striatum, crucial for the correct functioning of this brain region in adulthood, are known to be established early in development, but their role is currently uncharacterized. We demonstrate here that dopamine, by activating D(1)- and/or D(2)-dopamine receptors, decreases the number of functional GABAergic synapses formed between the embryonic precursors of the medium spiny neurons, the principal output neurons of the striatum, with associated changes in spontaneous synaptic activity. Activation of these receptors reduces the size of postsynaptic GABA(A) receptor clusters and their overall cell-surface expression, without affecting the total number of clusters or the size or number of GABAergic nerve terminals. These changes result from an increased internalization of GABA(A) receptors, and are mediated by distinct signaling pathways converging at the level of GABA(A) receptors to cause a transient PP2A/PP1-dependent dephosphorylation. Thus, tonic D(1)- and D(2)-receptor activity limits the extent of collateral inhibitory synaptogenesis between medium spiny neurons, revealing a novel role of dopamine in controlling the development of intrinsic striatal microcircuits.
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58
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Mizokami A, Tanaka H, Ishibashi H, Umebayashi H, Fukami K, Takenawa T, Nakayama KI, Yokoyama T, Nabekura J, Kanematsu T, Hirata M. GABA(A) receptor subunit alteration-dependent diazepam insensitivity in the cerebellum of phospholipase C-related inactive protein knockout mice. J Neurochem 2010; 114:302-10. [PMID: 20412381 DOI: 10.1111/j.1471-4159.2010.06754.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The GABA(A) receptor, a pentamer composed predominantly of alpha, beta, and gamma subunits, mediates fast inhibitory synaptic transmission. We have previously reported that phospholipase C-related inactive protein (PRIP) is a modulator of GABA(A) receptor trafficking and that knockout (KO) mice exhibit a diazepam-insensitive phenotype in the hippocampus. The alpha subunit affects diazepam sensitivity; alpha1, 2, 3, and 5 subunits assemble with any form of beta and the gamma2 subunits to produce diazepam-sensitive receptors, whereas alpha4 or alpha6/beta/gamma2 receptors are diazepam-insensitive. Here, we investigated how PRIP is implicated in the diazepam-insensitive phenotype using cerebellar granule cells in animals expressing predominantly the alpha6 subunit. The expression of alpha1/beta/gamma2 diazepam-sensitive receptors was decreased in the PRIP-1 and 2 double KO cerebellum without any change in the total number of benzodiazepine-binding sites as assessed by radioligand-binding assay. Since levels of the alpha6 subunit were increased, the alpha1/beta/gamma2 receptors might be replaced with alpha6 subunit-containing receptors. Then, we further performed autoradiographic and electrophysiologic analyses. These results suggest that the expression of alpha6/delta receptors was decreased in cerebellar granule neurons, while that of alpha6/gamma2 receptors was increased. PRIP-1 and 2 double KO mice exhibit a diazepam-insensitive phenotype because of a decrease in diazepam-sensitive (alpha1/gamma2) and increase in diazepam-insensitive (alpha6/gamma2) GABA(A) receptors in the cerebellar granule cells.
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Affiliation(s)
- Akiko Mizokami
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, and Station for Collaborative Research, Kyushu University, Fukuoka, Japan
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59
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Kanematsu T, Fujii M, Tanaka H, Umebayashi H, Hirata M. Surface Expression of GABAA Receptors. J Oral Biosci 2010. [DOI: 10.1016/s1349-0079(10)80012-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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60
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Fujii M, Kanematsu T, Ishibashi H, Fukami K, Takenawa T, Nakayama KI, Moss SJ, Nabekura J, Hirata M. Phospholipase C-related but catalytically inactive protein is required for insulin-induced cell surface expression of gamma-aminobutyric acid type A receptors. J Biol Chem 2009; 285:4837-46. [PMID: 19996098 DOI: 10.1074/jbc.m109.070045] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The gamma-aminobutyric acid type A (GABA(A)) receptors play a pivotal role in fast synaptic inhibition in the central nervous system. One of the key factors for determining synaptic strength is the number of receptors on the postsynaptic membrane, which is maintained by the balance between cell surface insertion and endocytosis of the receptors. In this study, we investigated whether phospholipase C-related but catalytically inactive protein (PRIP) is involved in insulin-induced GABA(A) receptor insertion. Insulin potentiated the GABA-induced Cl(-) current (I(GABA)) by about 30% in wild-type neurons, but not in PRIP1 and PRIP2 double-knock-out (DKO) neurons, suggesting that PRIP is involved in insulin-induced potentiation. The phosphorylation level of the GABA(A) receptor beta-subunit was increased by about 30% in the wild-type neurons but not in the mutant neurons, which were similar to the changes observed in I(GABA). We also revealed that PRIP recruited active Akt to the GABA(A) receptors by forming a ternary complex under insulin stimulation. The disruption of the binding between PRIP and the GABA(A) receptor beta-subunit by PRIP interference peptide attenuated the insulin potentiation of I(GABA). Taken together, these results suggest that PRIP is involved in insulin-induced GABA(A) receptor insertion by recruiting active Akt to the receptor complex.
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Affiliation(s)
- Makoto Fujii
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, and Station for Collaborative Research, Kyushu University, Fukuoka 812-8582, Japan
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61
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Matsuda M, Tsutsumi K, Kanematsu T, Fukami K, Terada Y, Takenawa T, Nakayama KI, Hirata M. Involvement of Phospholipase C-Related Inactive Protein in the Mouse Reproductive System Through the Regulation of Gonadotropin Levels1. Biol Reprod 2009; 81:681-9. [DOI: 10.1095/biolreprod.109.076760] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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62
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Joshi S, Kapur J. Slow intracellular accumulation of GABA(A) receptor delta subunit is modulated by brain-derived neurotrophic factor. Neuroscience 2009; 164:507-19. [PMID: 19665523 DOI: 10.1016/j.neuroscience.2009.08.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 08/03/2009] [Accepted: 08/04/2009] [Indexed: 11/26/2022]
Abstract
GABA(A) receptors composed of the gamma2 and delta subunits have distinct properties, functions and subcellular localization, and pathological conditions differentially modulate their surface expression. Recent studies demonstrate that acute seizure activity accelerated trafficking of the gamma2 and beta2/3 subunits but not that of the delta subunit. The trafficking of the gamma2 and beta2/3 subunits is relatively well understood but that of the delta subunit has not been studied. We compared intracellular accumulation of the delta and gamma2 subunits in cultured hippocampal neurons using an antibody feeding technique. Intracellular accumulation of the delta subunit peaked between 3 and 6 h, whereas, maximum internalization of the gamma2 subunit took 30 min. In the organotypic hippocampal slice cultures internalization of the delta subunit studied using a biotinylation assay revealed highest accumulation between 3 and 5 h and that of the gamma2 subunit between 15 and 45 min. The surface half-life of the delta subunit was 171 min in cultured hippocampal neurons and 102 min in the organotypic hippocampal slice cultures. In the subsequent studies, internalization of the delta subunit was found to be dependent on network activity but independent of ligand-binding. Brain-derived neurotrophic factor (BDNF) reduced buildup of the delta subunit in the cytoplasmic compartments and increased its surface expression, and this BDNF effect was independent of network activity. BDNF effect was mediated by activation of TrkB receptors, PLCgamma and PKC. Increase in the basal PKC activity augmented cell surface stability of the delta subunit. These results suggest that rate of intracellular accumulation of the delta subunit was distinct and modulated by BDNF.
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Affiliation(s)
- S Joshi
- Department of Neurology, Box 800394, University of Virginia, Health Sciences Center, Charlottesville, VA 22908, USA
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63
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Mohrlüder J, Schwarten M, Willbold D. Structure and potential function of gamma-aminobutyrate type A receptor-associated protein. FEBS J 2009; 276:4989-5005. [PMID: 19674112 DOI: 10.1111/j.1742-4658.2009.07207.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The gamma-aminobutyrate type A receptor-associated protein (GABARAP) is a ubiquitin-like modifier, and is implicated in a variety of membrane trafficking and fusion events that are crucial to synaptic plasticity, autophagy and apoptosis. However, important aspects of GABARAP function and regulation remain poorly understood. We review the current state of knowledge about GABARAP, highlighting newly-identified GABARAP ligands, and discuss the possible physiological relevance of each ligand interaction.
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Affiliation(s)
- Jeannine Mohrlüder
- Institut für Strukturbiologie und Biophysik (ISB-3), Forschungszentrum Jülich, Germany.
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64
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Modulation of gamma-aminobutyric acid on painful sense in central nervous system of morphine-dependent rats. Neurosci Bull 2009; 24:278-82. [PMID: 18839020 DOI: 10.1007/s12264-008-0227-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
OBJECTIVE To observe the effects of gamma-aminobutyric acid (GABA) on the electric activities of pain-excited neurons (PEN) in nucleus accumbens (NAc) in central nervous system (CNS) of morphine-dependent rats. METHODS After GABA or the GABA(A)-receptor antagonist, bicuculline (Bic), was injected into cerebral ventricles or NAc, right sciatic nerve was stimulated by electrical pulses, which was considered as traumatic pain stimulation. Extracellular recordings methods were used to record the electric activities of PEN in NAc. RESULTS When GABA was injected into intracerebroventricle (ICV) as well as NAc, it could decrease the pain-evoked discharge frequency and prolong the latency of PEN. Bic could interdict the above effects of GABA on the electric activities of PEN. CONCLUSION Exogenous GABA might have an inhibitory effect on the central pain adjustment. Furthermore, GABA and GABA(A) receptor participate and mediate the traumatic information transmission process in CNS.
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65
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Fritschy JM. Epilepsy, E/I Balance and GABA(A) Receptor Plasticity. Front Mol Neurosci 2008; 1:5. [PMID: 18946538 PMCID: PMC2525999 DOI: 10.3389/neuro.02.005.2008] [Citation(s) in RCA: 199] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Accepted: 01/30/2008] [Indexed: 01/26/2023] Open
Abstract
GABAA receptors mediate most of the fast inhibitory transmission in the CNS. They form heteromeric complexes assembled from a large family of subunit genes. The existence of multiple GABAA receptor subtypes differing in subunit composition, localization and functional properties underlies their role for fine-tuning of neuronal circuits and genesis of network oscillations. The differential regulation of GABAA receptor subtypes represents a major facet of homeostatic synaptic plasticity and contributes to the excitation/inhibition (E/I) balance under physiological conditions and upon pathological challenges. The purpose of this review is to discuss recent findings highlighting the significance of GABAA receptor heterogeneity for the concept of E/I balance and its relevance for epilepsy. Specifically, we address the following issues: (1) role for tonic inhibition, mediated by extrasynaptic GABAA receptors, for controlling neuronal excitability; (2) significance of chloride ion transport for maintenance of the E/I balance in adult brain; and (3) molecular mechanisms underlying GABAA receptor regulation (trafficking, posttranslational modification, gene transcription) that are important for homoeostatic plasticity. Finally, the relevance of these findings is discussed in light of the involvement of GABAA receptors in epileptic disorders, based on recent experimental studies of temporal lobe epilepsy (TLE) and absence seizures and on the identification of mutations in GABAA receptor subunit genes underlying familial forms of epilepsy.
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Affiliation(s)
- Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology, University of Zurich Zurich, Switzerland
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66
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Mizokami A, Kanematsu T, Ishibashi H, Yamaguchi T, Tanida I, Takenaka K, Nakayama KI, Fukami K, Takenawa T, Kominami E, Moss SJ, Yamamoto T, Nabekura J, Hirata M. Phospholipase C-related inactive protein is involved in trafficking of gamma2 subunit-containing GABA(A) receptors to the cell surface. J Neurosci 2007; 27:1692-701. [PMID: 17301177 PMCID: PMC6673751 DOI: 10.1523/jneurosci.3155-06.2007] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The subunit composition of GABA(A) receptors is known to be associated with distinct physiological and pharmacological properties. Previous studies that used phospholipase C-related inactive protein type 1 knock-out (PRIP-1 KO) mice revealed that PRIP-1 is involved in the assembly and/or the trafficking of gamma2 subunit-containing GABA(A) receptors. There are two PRIP genes in mammals; thus the roles of PRIP-1 might be compensated partly by those of PRIP-2 in PRIP-1 KO mice. Here we used PRIP-1 and PRIP-2 double knock-out (PRIP-DKO) mice and examined the roles for PRIP in regulating the trafficking of GABA(A) receptors. Consistent with previous results, sensitivity to diazepam was reduced in electrophysiological and behavioral analyses of PRIP-DKO mice, suggesting an alteration of gamma2 subunit-containing GABA(A) receptors. The surface numbers of diazepam binding sites (alpha/gamma2 subunits) assessed by [3H]flumazenil binding were reduced in the PRIP-DKO mice as compared with those of wild-type mice, whereas the cell surface GABA binding sites (alpha/beta subunits, assessed by [3H]muscimol binding) were increased in PRIP-DKO mice. The association between GABA(A) receptors and GABA(A) receptor-associated protein (GABARAP) was reduced significantly in PRIP-DKO neurons. Disruption of the direct interaction between PRIP and GABA(A) receptor beta subunits via the use of a peptide corresponding to the PRIP-1 binding site reduced the cell surface expression of gamma2 subunit-containing GABA(A) receptors in cultured cell lines and neurons. These results suggest that PRIP is implicated in the trafficking of gamma2 subunit-containing GABA(A) receptors to the cell surface, probably by acting as a bridging molecule between GABARAP and the receptors.
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Affiliation(s)
- Akiko Mizokami
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, and Station for Collaborative Research
| | - Takashi Kanematsu
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, and Station for Collaborative Research
| | - Hitoshi Ishibashi
- Department of Cellular and System Physiology, Faculty of Medical Science, and
| | - Taku Yamaguchi
- Department of Neuropharmacology, Graduate School of Medicine, Hokkaido University, Sapporo 060-8638, Japan
| | - Isei Tanida
- Department of Biochemistry, Juntendo University School of Medicine, Tokyo 113-8421, Japan
| | - Kei Takenaka
- Department of Biochemistry, Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| | - Keiichi I. Nakayama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Kiyoko Fukami
- Laboratory of Genome and Biosignal, Tokyo University of Pharmacy and Life Science, Tokyo 192-0392, Japan
| | - Tadaomi Takenawa
- Department of Biochemistry, Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| | - Eiki Kominami
- Department of Biochemistry, Juntendo University School of Medicine, Tokyo 113-8421, Japan
| | - Stephen J. Moss
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
| | - Tsuneyuki Yamamoto
- Department of Pharmacology, Faculty of Pharmaceutical Science, Nagasaki International University, Nagasaki 859-3298, Japan, and
| | - Junichi Nabekura
- Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
| | - Masato Hirata
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, and Station for Collaborative Research
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67
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Wake H, Watanabe M, Moorhouse AJ, Kanematsu T, Horibe S, Matsukawa N, Asai K, Ojika K, Hirata M, Nabekura J. Early changes in KCC2 phosphorylation in response to neuronal stress result in functional downregulation. J Neurosci 2007; 27:1642-50. [PMID: 17301172 PMCID: PMC6673731 DOI: 10.1523/jneurosci.3104-06.2007] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Revised: 01/04/2007] [Accepted: 01/05/2007] [Indexed: 01/26/2023] Open
Abstract
The K+ Cl- cotransporter KCC2 plays an important role in chloride homeostasis and in neuronal responses mediated by ionotropic GABA and glycine receptors. The expression levels of KCC2 in neurons determine whether neurotransmitter responses are inhibitory or excitatory. KCC2 expression is decreased in developing neurons, as well as in response to various models of neuronal injury and epilepsy. We investigated whether there is also direct modulation of KCC2 activity by changes in phosphorylation during such neuronal stressors. We examined tyrosine phosphorylation of KCC2 in rat hippocampal neurons under different conditions of in vitro neuronal stress and the functional consequences of changes in tyrosine phosphorylation. Oxidative stress (H2O2) and the induction of seizure activity (BDNF) and hyperexcitability (0 Mg2+) resulted in a rapid dephosphorylation of KCC2 that preceded the decreases in KCC2 protein or mRNA expression. Dephosphorylation of KCC2 is correlated with a reduction of transport activity and a decrease in [Cl-]i, as well as a reduction in KCC2 surface expression. Manipulation of KCC2 tyrosine phosphorylation resulted in altered neuronal viability in response to in vitro oxidative stress. During continued neuronal stress, a second phase of functional KCC2 downregulation occurs that corresponds to decreases in KCC2 protein expression levels. We propose that neuronal stress induces a rapid loss of tyrosine phosphorylation of KCC2 that results in translocation of the protein and functional loss of transport activity. Additional understanding of the mechanisms involved may provide means for manipulating the extent of irreversible injury resulting from different neuronal stressors.
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Affiliation(s)
- Hiroaki Wake
- Division of Homeostatic Development, National Institute of Physiological Sciences, Okazaki 444-8585, Japan
- Department of Neurology and Neuroscience, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya 467-8601, Japan
| | - Miho Watanabe
- Division of Homeostatic Development, National Institute of Physiological Sciences, Okazaki 444-8585, Japan
| | - Andrew J. Moorhouse
- Department of Physiology and Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Takashi Kanematsu
- Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan
| | - Shoko Horibe
- Division of Homeostatic Development, National Institute of Physiological Sciences, Okazaki 444-8585, Japan
- School of Life Science, The Graduate University for Advanced Studies, Hayama 240-0193, Japan, and
| | - Noriyuki Matsukawa
- Department of Neurology and Neuroscience, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya 467-8601, Japan
| | - Kiyofumi Asai
- Department of Molecular Neurobiology, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan
| | - Kosei Ojika
- Department of Neurology and Neuroscience, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya 467-8601, Japan
| | - Masato Hirata
- Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan
| | - Junichi Nabekura
- Division of Homeostatic Development, National Institute of Physiological Sciences, Okazaki 444-8585, Japan
- School of Life Science, The Graduate University for Advanced Studies, Hayama 240-0193, Japan, and
- Core Research for the Evolutionary Science and Technology, Japan Science and Technology Corporation, Saitama 332-0012, Japan
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Kanematsu T, Fujii M, Mizokami A, Kittler JT, Nabekura J, Moss SJ, Hirata M. Phospholipase C-related inactive protein is implicated in the constitutive internalization of GABAA receptors mediated by clathrin and AP2 adaptor complex. J Neurochem 2007; 101:898-905. [PMID: 17254016 DOI: 10.1111/j.1471-4159.2006.04399.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A mechanism for regulating the strength of synaptic inhibition is enabled by altering the number of GABA(A) receptors available at the cell surface. Clathrin and adaptor protein 2 (AP2) complex-mediated endocytosis is known to play a fundamental role in regulating cell surface GABA(A) receptor numbers. Very recently, we have elucidated that phospholipase C-related catalytically inactive protein (PRIP) molecules are involved in the phosphorylation-dependent regulation of the internalization of GABA(A) receptors through association with receptor beta subunits and protein phosphatases. In this study, we examined the implications of PRIP molecules in clathrin-mediated constitutive GABA(A) receptor endocytosis, independent of phospho-regulation. We performed a constitutive receptor internalization assay using human embryonic kidney 293 (HEK293) cells transiently expressed with GABA(A) receptor alpha/beta/gamma subunits and PRIP. PRIP was internalized together with GABA(A) receptors, and the process was inhibited by PRIP-binding peptide which blocks PRIP binding to beta subunits. The clathrin heavy chain, mu2 and beta2 subunits of AP2 and PRIP-1, were complexed with GABA(A) receptor in brain extract as analyzed by co-immunoprecipitation assay using anti-PRIP-1 and anti-beta2/3 GABA(A) receptor antibody or by pull-down assay using beta subunits of GABA(A) receptor. These results indicate that PRIP is primarily implicated in the constitutive internalization of GABA(A) receptor that requires clathrin and AP2 protein complex.
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Affiliation(s)
- Takashi Kanematsu
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, and Station for Collaborative Research, Kyushu University, Fukuoka, Japan
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Kanematsu T, Mizokami A, Terunuma M, Takeuchi H, Hirata M. Identification of a Novel Signaling Molecule and Elucidation of Its Cellular Functions —Development of an Interface between Neuroscience and Oral Health Science—. J Oral Biosci 2007. [DOI: 10.1016/s1349-0079(07)80020-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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70
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Kanematsu T, Mizokami A, Watanabe K, Hirata M. Regulation of GABAA-Receptor Surface Expression With Special Reference to the Involvement of GABARAP (GABAA Receptor-Associated Protein) and PRIP (Phospholipase C-Related, but Catalytically Inactive Protein). J Pharmacol Sci 2007; 104:285-92. [PMID: 17690529 DOI: 10.1254/jphs.cp0070063] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
GABA(A) receptors are heteropentameric ligand-gated chloride channels composed of a variety of subunits, including alpha1 - 6, beta1 - 3, gamma1 - 3, delta, epsilon, theta, and pi, and play a key role in controlling inhibitory neuronal activity. Modification of the efficacy of the synaptic strength is produced by changes in both the number of neuronal surface receptors and pentameric molecular assembly, leading to differences of sensitivity to neurotransmitters and neuromimetic drugs. Therefore, it is important to understand the molecular mechanisms regulating the so-called "life cycle of GABA(A) receptors" including sequential pentameric assembly at the site synthesized, intracellular transport through the Golgi apparatus and the cytoplasm, insertion into the cell membrane, functional modulation at the cell surface, and finally internalization, followed by either recycling back to the surface membrane or lysosomal degradation. This review is focused on events related to the surface expression of the receptor containing the gamma2 subunit and clathrin/AP2 complex-mediated phospho-regulated endocytosis of the receptor, with special reference to the function of novel GABA(A) receptor modulators, GABARAP (GABA(A) receptor-associated protein) and PRIP (phospholipase C-related, but catalytically inactive protein).
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Affiliation(s)
- Takashi Kanematsu
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science and Station for Collaborative Research, Kyushu University, Fukuoka, Japan.
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71
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Kanematsu T, Mizokami A, Terunuma M, Takeuchi H, Hirata M. Identification of a Novel Signaling Molecule and Elucidation of Its Cellular Functions-Development of an Interface between Neuroscience and Oral Health Science-. J Oral Biosci 2007. [DOI: 10.2330/joralbiosci.49.244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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72
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Mizokami A, Kanematsu T, Hirata M. Roles of PRIP in GABAA Receptor Signaling. J Oral Biosci 2007. [DOI: 10.1016/s1349-0079(07)80003-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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73
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Murakami A, Matsuda M, Nakasima A, Hirata M. Characterization of the human PRIP-1 gene structure and transcriptional regulation. Gene 2006; 382:129-39. [PMID: 16952428 DOI: 10.1016/j.gene.2006.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Revised: 06/15/2006] [Accepted: 07/07/2006] [Indexed: 01/01/2023]
Abstract
The PRIP [phospholipase C related, but catalytically inactive protein] family has been isolated as a novel inositol 1,4,5-trisphosphate binding protein with a domain organization similar to phospholipase C-delta but lacking the enzyme activity, comprising PRIP-1 and PRIP-2. The PRIP-1 gene is expressed predominantly in the brain, while PRIP-2 exhibits a relatively ubiquitous expression in rats and mice. We also found that PRIP-1 plays an important role in type A receptor signaling for gamma-aminobutyric acid in the brain. In this study, we investigated PRIP-1 gene structure and the possible mechanisms involved in the expression. The tissue distribution pattern of PRIP gene expression in humans was similar to that in rodents. 5'RACE (rapid amplification of cDNA ends) analysis using PRIP-1 gene specific primers with human brain mRNA revealed the presence of three new exons, indicating that the PRIP-1 gene is organized into 8 exons intervened by 7 introns. Although three transcripts resulting from the alternative splicing of exon 2 and/or 3 were detected, a transcript lacking exons 2 and 3 was predominantly expressed in humans, suggesting that the translation start codon of human PRIP-1 exists in exon 1. To characterize the human PRIP-1 promoter, transient luciferase assay was carried out with luciferase constructs including various lengths of the 5' flanking region of the PRIP-1 gene. The results indicated that the positive regulatory region is located -237 to -108 bp upstream from the transcription start site. Gel shift assay revealed the specific binding of some nuclear proteins to this region, suggesting that the existence of transcription factors contributes to the positive regulation of PRIP-1 gene expression. Mutation analyses revealed that the binding of a transcription factor, MAZ to the regulatory site leads to the promoter activity, indicating that MAZ is involved in the expression regulation of the human PRIP-1 gene.
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Affiliation(s)
- Ayako Murakami
- Laboratory of Molecular and Cellular Biochemistry, Kyushu University, Fukuoka 812-8582, Japan
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