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Ando H, Shimizu-Okabe C, Okura N, Yafuso T, Kosaka Y, Kobayashi S, Okabe A, Takayama C. Reduced Gene Expression of KCC2 Accelerates Axonal Regeneration and Reduces Motor Dysfunctions after Tibial Nerve Severance and Suturing. Neuroscience 2024; 551:55-68. [PMID: 38788828 DOI: 10.1016/j.neuroscience.2024.05.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/09/2024] [Accepted: 05/15/2024] [Indexed: 05/26/2024]
Abstract
Gamma-aminobutyric acid and glycine (GABA/Gly) are predominantly inhibitory neurotransmitters in the mature central nervous system; however, they mediate membrane potential depolarization during development. These differences in actions depend on intracellular Cl- concentrations ([Cl-]i), which are primarily regulated by potassium chloride cotransporter 2 (KCC2). After nerve injury, KCC2 expression markedly decreases and GABA/Gly mediate depolarization. Following nerve regeneration, KCC2 expression recovers and GABA/Gly become inhibitory, suggesting that KCC2 reduction and GABA/Gly excitation may be crucial for axonal regeneration. To directly clarify their involvement in regeneration, we analyzed recovery processes after tibial nerve severance and suturing between heterozygous KCC2 knockout mice (HT), whose KCC2 levels are halved, and their wild-type littermates (WT). Compared with WT mice, the sciatic functional index-indicating lower limb motor function-was significantly higher until 28 days after operation (D28) in HT mice. Furthermore, at D7, many neurofilament-positive fibers were elongated into the distal part of the sutured nerve in HT mice only, and myelinated axonal density was significantly higher at D21 and D28 in HT animals. Electron microscopy and galanin immunohistochemistry indicated a shorter nerve degeneration period in HT mice. Moreover, a less severe decrease in choline acetyltransferase was observed in HT mice. These results suggest that nerve degeneration and regeneration proceed more rapidly in HT mice, resulting in milder motor dysfunction. Via similar microglial activation, nerve surgery may reduce KCC2 levels more rapidly in HT mice, followed by earlier increased [Cl-]i and longer-lasting GABA/Gly excitation. Taken together, reduced KCC2 may accelerate nerve regeneration via GABA/Gly excitation.
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Affiliation(s)
- Hironobu Ando
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa 9030215, Japan
| | - Chigusa Shimizu-Okabe
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa 9030215, Japan
| | - Nobuhiko Okura
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa 9030215, Japan
| | - Tsukasa Yafuso
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa 9030215, Japan
| | - Yoshinori Kosaka
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa 9030215, Japan
| | - Shiori Kobayashi
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa 9030215, Japan
| | - Akihito Okabe
- Department of Nutritional Science, Faculty of Health and Welfare, Seinan Jo Gakuin University, Fukuoka 803-0835, Japan
| | - Chitoshi Takayama
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa 9030215, Japan.
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Huang 黄玉莹 Y, Chen 陈红 H, Shao 邵建英 JY, Zhou 周京京 JJ, Chen 陈少瑞 SR, Pan 潘惠麟 HL. Constitutive KCC2 Cell- and Synapse-Specifically Regulates NMDA Receptor Activity in the Spinal Cord. J Neurosci 2024; 44:e1943232023. [PMID: 38124193 PMCID: PMC10860486 DOI: 10.1523/jneurosci.1943-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 11/20/2023] [Accepted: 12/05/2023] [Indexed: 12/23/2023] Open
Abstract
K+-Cl- cotransporter-2 (KCC2) critically controls neuronal chloride homeostasis and maintains normal synaptic inhibition by GABA and glycine. Nerve injury diminishes synaptic inhibition in the spinal cord via KCC2 impairment. However, how KCC2 regulates nociceptive input to spinal excitatory and inhibitory neurons remains elusive. Here, we show that basal GABA reversal potentials were significantly more depolarized in vesicular GABA transporter (VGAT)-expressing inhibitory neurons than those in vesicular glutamate transporter-2 (VGluT2)-expressing excitatory neurons in spinal cords of male and female mice. Strikingly, inhibiting KCC2 with VU0463271 increased currents elicited by puff NMDA and the NMDAR-mediated frequency of mEPSCs in VGluT2, but not in VGAT, dorsal horn neurons. Notably, VU0463271 had no effect on EPSCs monosynaptically evoked from the dorsal root in VGluT2 neurons. Furthermore, VU0463271 augmented α2δ-1-NMDAR interactions and their protein levels in spinal cord synaptosomes. In Cacna2d1 KO mice, VU0463271 had no effect on puff NMDA currents or the mEPSC frequency in dorsal horn neurons. Disrupting α2δ-1-NMDAR interactions with α2δ-1 C-terminus mimicking peptide diminished VU0463271-induced potentiation in the mEPSC frequency and puff NMDA currents in VGluT2 neurons. Additionally, intrathecal injection of VU0463271 reduced mechanical and thermal thresholds in wild-type mice, but not in Cacna2d1 KO mice. VU0463271-induced pain hypersensitivity in mice was abrogated by co-treatment with the NMDAR antagonist, pregabalin (an α2δ-1 inhibitory ligand), or α2δ-1 C-terminus mimicking peptide. Our findings suggest that KCC2 controls presynaptic and postsynaptic NMDAR activity specifically in excitatory dorsal horn neurons. KCC2 impairment preferentially potentiates nociceptive transmission between spinal excitatory interneurons via α2δ-1-bound NMDARs.Significance statementImpaired function of potassium-chloride cotransporter-2 (KCC2), a key regulator of neuronal inhibition, in the spinal cord plays a major role in neuropathic pain. This study unveils that KCC2 controls spinal nociceptive synaptic strength via NMDA receptors in a cell type- and synapse type-specific manner. KCC2 inhibition preferentially augments presynaptic and postsynaptic NMDA receptor activity in spinal excitatory interneurons via α2δ-1 (previously known as a calcium channel subunit). Importantly, spinal KCC2 impairment triggers pain hypersensitivity through α2δ-1-coupled NMDA receptors. These findings pinpoint the cell and molecular substrates for the reciprocal relationship between spinal synaptic inhibition and excitation in chronic neuropathic pain. Targeting both KCC2 and α2δ-1–NMDA receptor complexes could be an effective strategy in managing neuropathic pain conditions.
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Affiliation(s)
- Yuying Huang 黄玉莹
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston 77030, Texas
| | - Hong Chen 陈红
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston 77030, Texas
| | - Jian-Ying Shao 邵建英
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston 77030, Texas
| | - Jing-Jing Zhou 周京京
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston 77030, Texas
| | - Shao-Rui Chen 陈少瑞
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston 77030, Texas
| | - Hui-Lin Pan 潘惠麟
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston 77030, Texas
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3
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Pethe A, Hamze M, Giannaki M, Heimrich B, Medina I, Hartmann AM, Roussa E. K +/Cl - cotransporter 2 (KCC2) and Na +/ HCO3- cotransporter 1 (NBCe1) interaction modulates profile of KCC2 phosphorylation. Front Cell Neurosci 2023; 17:1253424. [PMID: 37881493 PMCID: PMC10595033 DOI: 10.3389/fncel.2023.1253424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 09/07/2023] [Indexed: 10/27/2023] Open
Abstract
K+/Cl- cotransporter 2 (KCC2) is a major Cl- extruder in mature neurons and is responsible for the establishment of low intracellular [Cl-], necessary for fast hyperpolarizing GABAA-receptor mediated synaptic inhibition. Electrogenic sodium bicarbonate cotransporter 1 (NBCe1) is a pH regulatory protein expressed in neurons and glial cells. An interactome study identified NBCe1 as a possible interaction partner of KCC2. In this study, we investigated the putative effect of KCC2/NBCe1 interaction in baseline and the stimulus-induced phosphorylation pattern and function of KCC2. Primary mouse hippocampal neuronal cultures from wildtype (WT) and Nbce1-deficient mice, as well as HEK-293 cells stably transfected with KCC2WT, were used. The results show that KCC2 and NBCe1 are interaction partners in the mouse brain. In HEKKCC2 cells, pharmacological inhibition of NBCs with S0859 prevented staurosporine- and 4-aminopyridine (4AP)-induced KCC2 activation. In mature cultures of hippocampal neurons, however, S0859 completely inhibited postsynaptic GABAAR and, thus, could not be used as a tool to investigate the role of NBCs in GABA-dependent neuronal networks. In Nbce1-deficient immature hippocampal neurons, baseline phosphorylation of KCC2 at S940 was downregulated, compared to WT, and exposure to staurosporine failed to reduce pKCC2 S940 and T1007. In Nbce1-deficient mature neurons, baseline levels of pKCC2 S940 and T1007 were upregulated compared to WT, whereas after 4AP treatment, pKCC2 S940 was downregulated, and pKCC2 T1007 was further upregulated. Functional experiments showed that the levels of GABAAR reversal potential, baseline intracellular [Cl-], Cl- extrusion, and baseline intracellular pH were similar between WT and Nbce1-deficient neurons. Altogether, our data provide a primary description of the properties of KCC2/NBCe1 protein-protein interaction and implicate modulation of stimulus-mediated phosphorylation of KCC2 by NBCe1/KCC2 interaction-a mechanism with putative pathophysiological relevance.
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Affiliation(s)
- Abhishek Pethe
- Department of Molecular Embryology, Faculty of Medicine, Institute for Anatomy and Cell Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Mira Hamze
- INMED, INSERM, Aix-Marseille University, Marseille, France
| | - Marina Giannaki
- Department of Molecular Embryology, Faculty of Medicine, Institute for Anatomy and Cell Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Bernd Heimrich
- Department of Neuroanatomy, Faculty of Medicine, Institute for Anatomy and Cell Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Igor Medina
- INMED, INSERM, Aix-Marseille University, Marseille, France
| | - Anna-Maria Hartmann
- Division of Neurogenetics, Faculty VI, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
- Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Eleni Roussa
- Department of Molecular Embryology, Faculty of Medicine, Institute for Anatomy and Cell Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
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Byvaltcev E, Behbood M, Schleimer JH, Gensch T, Semyanov A, Schreiber S, Strauss U. KCC2 reverse mode helps to clear postsynaptically released potassium at glutamatergic synapses. Cell Rep 2023; 42:112934. [PMID: 37537840 PMCID: PMC10480490 DOI: 10.1016/j.celrep.2023.112934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 07/09/2023] [Accepted: 07/18/2023] [Indexed: 08/05/2023] Open
Abstract
Extracellular potassium [K+]o elevation during synaptic activity retrogradely modifies presynaptic release and astrocytic uptake of glutamate. Hence, local K+ clearance and replenishment mechanisms are crucial regulators of glutamatergic transmission and plasticity. Based on recordings of astrocytic inward rectifier potassium current IKir and K+-sensitive electrodes as sensors of [K+]o as well as on in silico modeling, we demonstrate that the neuronal K+-Cl- co-transporter KCC2 clears local perisynaptic [K+]o during synaptic excitation by operating in an activity-dependent reversed mode. In reverse mode, KCC2 replenishes K+ in dendritic spines and complements clearance of [K+]o, therewith attenuating presynaptic glutamate release and shortening LTP. We thus demonstrate a physiological role of KCC2 in neuron-glial interactions and regulation of synaptic signaling and plasticity through the uptake of postsynaptically released K+.
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Affiliation(s)
- Egor Byvaltcev
- Charité - Universitätsmedizin Berlin, Institute of Cell- and Neurobiology, Charitéplatz 1, 10117 Berlin, Germany
| | - Mahraz Behbood
- Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, 10115 Berlin, Germany; Bernstein Center for Computational Neuroscience Berlin, 10115 Berlin, Germany
| | - Jan-Hendrik Schleimer
- Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, 10115 Berlin, Germany; Bernstein Center for Computational Neuroscience Berlin, 10115 Berlin, Germany
| | - Thomas Gensch
- Institute of Biological Information Processing 1 (IBI-1, Molecular and Cellular Physiology), Forschungszentrum Jülich, Wilhem-Jonen Straße, 52428 Jülich, Germany
| | - Alexey Semyanov
- Department of Physiology, Jiaxing University College of Medicine, Zhejiang Pro, Jiaxing 314033, China
| | - Susanne Schreiber
- Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, 10115 Berlin, Germany; Bernstein Center for Computational Neuroscience Berlin, 10115 Berlin, Germany
| | - Ulf Strauss
- Charité - Universitätsmedizin Berlin, Institute of Cell- and Neurobiology, Charitéplatz 1, 10117 Berlin, Germany.
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Breitinger U, Breitinger HG. Excitatory and inhibitory neuronal signaling in inflammatory and diabetic neuropathic pain. Mol Med 2023; 29:53. [PMID: 37069517 PMCID: PMC10111846 DOI: 10.1186/s10020-023-00647-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 03/27/2023] [Indexed: 04/19/2023] Open
Abstract
Pain, although unpleasant, is an essential warning mechanism against injury and damage of the organism. An intricate network of specialised sensors and transmission systems contributes to reception, transmission and central sensitization of pain. Here, we briefly introduce some of the main aspects of pain signal transmission, including nociceptors and nociceptive signals, mechanisms of inflammatory and neuropathic pain, and the situation of diabetes-associated neuropathic pain. The role of glia-astrocytes, microglia, satellite glia cells-and their specific channels, transporters and signaling pathways is described. A focus is on the contribution of inhibitory synaptic signaling to nociception and a possible role of glycine receptors in glucose-mediated analgesia and treatment-induced diabetic neuropathy. Inhibitory receptors such as GABAA- and glycine receptors are important contributors to nociceptive signaling; their contribution to altered pain sensation in diabetes may be of clinical relevance, and they could be promising therapeutic targets towards the development of novel analgesics.
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Affiliation(s)
- Ulrike Breitinger
- Department of Biochemistry, German University in Cairo, New Cairo, 11835, Egypt
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6
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Chloride ion dysregulation in epileptogenic neuronal networks. Neurobiol Dis 2023; 177:106000. [PMID: 36638891 DOI: 10.1016/j.nbd.2023.106000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/25/2022] [Accepted: 01/09/2023] [Indexed: 01/13/2023] Open
Abstract
GABA is the major inhibitory neurotransmitter in the mature CNS. When GABAA receptors are activated the membrane potential is driven towards hyperpolarization due to chloride entry into the neuron. However, chloride ion dysregulation that alters the ionic gradient can result in depolarizing GABAergic post-synaptic potentials instead. In this review, we highlight that GABAergic inhibition prevents and restrains focal seizures but then reexamine this notion in the context of evidence that a static and/or a dynamic chloride ion dysregulation, that increases intracellular chloride ion concentrations, promotes epileptiform activity and seizures. To reconcile these findings, we hypothesize that epileptogenic pathologically interconnected neuron (PIN) microcircuits, representing a small minority of neurons, exhibit static chloride dysregulation and should exhibit depolarizing inhibitory post-synaptic potentials (IPSPs). We speculate that chloride ion dysregulation and PIN cluster activation may generate fast ripples and epileptiform spikes as well as initiate the hypersynchronous seizure onset pattern and microseizures. Also, we discuss the genetic, molecular, and cellular players important in chloride dysregulation which regulate epileptogenesis and initiate the low-voltage fast seizure onset pattern. We conclude that chloride dysregulation in neuronal networks appears to be critical for epileptogenesis and seizure genesis, but feed-back and feed-forward inhibitory GABAergic neurotransmission plays an important role in preventing and restraining seizures as well.
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7
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Jones EF, Butler MG, Trendafilova D, Mendez MS, Jernigan LA, Gahtan E, Steele J. In vivo tracking of KCC2b expression during early brain development. J Comp Neurol 2022; 531:48-57. [PMID: 36217249 DOI: 10.1002/cne.25411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 08/03/2022] [Accepted: 08/27/2022] [Indexed: 11/07/2022]
Abstract
The neuronal chloride (Cl-) exporter, KCC2, regulates neuron excitability and development and undergoes a stereotypical pattern of delayed upregulation as neurons mature. KCC2 upregulation favors neural inhibition by establishing a negative Cl- gradient, ensuring GABA-induced Cl- currents are inward and inhibitory. We developed a zebrafish fluorescent reporter line, KCC2b:mCitrine, to track KCC2 expression in vivo during early brain development. KCC2b:mCitrine was first detected at 16 h postfertilization and by day 6 labeled most central and peripheral neurons and processes. At 20 h, expression was greatest in the soma-dense basal neuroepithelium but largely absent in apical and mantle zones where differentiation and migration primarily occur, and time lapse imaging at this stage supports a postmigration upregulation of KCC2b. Central dopamine neurons showed low KCC2b expression as observed in other species. KCC2b:mCitrine fluorescence was stable over minutes in most neurons, but brightness transients observed in single cells fit our expectation for real-time tracking of KCC2b upregulation in new neurons. To further assess whether fluorescence brightness tracks KCC2b expression, zebrafish embryos were exposed to bisphenol-A (BPA), which is known to suppress KCC2 expression. Fluorescence decreased after 6 days of BPA exposure but not after 2 or 4 days, suggesting that it is an accurate but delayed indicator of KCC2b expression. KCC2b:mCitrine zebrafish present a new method for visualizing KCC2b's complex dynamics during brain development, and potentially screening compounds aimed at modulating KCC2 expression.
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Affiliation(s)
- Emma F Jones
- Department of Psychology, Cal Poly Humboldt, Arcata, California, USA.,Department of Biology, Cal Poly Humboldt, Arcata, California, USA
| | | | | | - Mayra S Mendez
- Department of Psychology, Cal Poly Humboldt, Arcata, California, USA
| | - Luke A Jernigan
- Department of Chemistry, Cal Poly Humboldt, Arcata, California, USA
| | - Ethan Gahtan
- Department of Psychology, Cal Poly Humboldt, Arcata, California, USA.,Department of Biology, Cal Poly Humboldt, Arcata, California, USA
| | - John Steele
- Department of Biology, Cal Poly Humboldt, Arcata, California, USA
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8
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Yafuso T, Kosaka Y, Shimizu-Okabe C, Okura N, Kobayashi S, Kim J, Matsuda K, Kinjo D, Okabe A, Takayama C. Slow progression of sciatic nerve degeneration and regeneration after loose ligation through microglial activation and decreased KCC2 levels in the mouse spinal cord ventral horn. Neurosci Res 2022; 177:52-63. [PMID: 34757085 DOI: 10.1016/j.neures.2021.10.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/17/2021] [Accepted: 10/25/2021] [Indexed: 10/20/2022]
Abstract
Peripheral nerve injury affects motor functions. To reveal the mechanisms underlying motor dysfunction and recovery after nerve compression, which have not been precisely examined, we investigated the temporal relationship among changes in motor function, nerve histopathology, and marker molecule expression in the spinal cord after loose ligation of the mouse sciatic nerve. After ligation, sciatic motor function suddenly declined, and axons gradually degenerated. During degeneration, galanin was localized in motor neuron cell bodies. Then, in the ventral horn, microglia were activated, and expression of choline acetyltransferase (ChAT), a synthetic enzyme of acetylcholine, and potassium chloride co-transporter 2 (KCC2), which shifts the action of γ-amino butyric acid (GABA) and glycine to inhibitory, decreased. Motor function recovery was insufficient although axonal regeneration was complete. ChAT levels gradually recovered during axonal regeneration. When regeneration was nearly complete, microglial activation declined, and KCC2 expression started to increase. The KCC2 level sufficiently recovered when axonal regeneration was complete, suggesting that the excitatory action of GABA/glycine may participate in axonal regeneration. Furthermore, these changes proceeded slower than those after severance, suggesting that loose ligation, compression, may mediate slower progression of degeneration and regeneration than severance, and these changes may cause the motor dysfunction and its recovery.
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Affiliation(s)
- Tsukasa Yafuso
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa, 9030215, Japan
| | - Yoshinori Kosaka
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa, 9030215, Japan
| | - Chigusa Shimizu-Okabe
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa, 9030215, Japan
| | - Nobuhiko Okura
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa, 9030215, Japan
| | - Shiori Kobayashi
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa, 9030215, Japan
| | - Jeongtae Kim
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa, 9030215, Japan; Department of Anatomy, Kosin University College of Medicine, Busan, 49267, Republic of Korea
| | - Koyata Matsuda
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa, 9030215, Japan
| | - Daichi Kinjo
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa, 9030215, Japan
| | - Akihito Okabe
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa, 9030215, Japan; Department of Nutritional Science, Faculty of Health and Welfare, Seinan Jo Gakuin University, Fukuoka, 803-0835, Japan
| | - Chitoshi Takayama
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara, Okinawa, 9030215, Japan.
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9
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Kimmey BA, Wittenberg RE, Croicu A, Shadani N, Ostroumov A, Dani JA. The serotonin 2A receptor agonist TCB-2 attenuates heavy alcohol drinking and alcohol-induced midbrain inhibitory plasticity. Addict Biol 2022; 27:e13147. [PMID: 35229942 PMCID: PMC8896307 DOI: 10.1111/adb.13147] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 11/26/2021] [Accepted: 01/10/2022] [Indexed: 12/21/2022]
Abstract
Disruption of neuronal chloride ion (Cl- ) homeostasis has been linked to several pathological conditions, including substance use disorder, yet targeted pharmacotherapies are lacking. In this study, we explored the potential of serotonin 2A receptor (5-HT2A R) agonism to reduce alcohol consumption in male wild-type C57Bl/6J mice and to ameliorate alcohol-induced inhibitory plasticity in the midbrain. We found that administration of the putative 5-HT2A R agonist TCB-2 attenuated alcohol consumption and preference but did not alter water or saccharin consumption. We hypothesized that the selective behavioural effects of TCB-2 on alcohol drinking were due, at least in part, to effects of the agonist on ventral tegmental area (VTA) neurocircuitry. Alcohol consumption impairs Cl- transport in VTA GABA neurons, which acts as a molecular adaptation leading to increased alcohol self-administration. Using ex vivo electrophysiological recordings, we found that exposure to either intermittent volitional alcohol drinking or an acute alcohol injection diminished homeostatic Cl- transport in VTA GABA neurons. Critically, in vivo TCB-2 administration normalized Cl- transport in the VTA after alcohol exposure. Thus, we show a potent effect of alcohol consumption on VTA inhibitory circuitry, in the form of dysregulated Cl- homeostasis that is reversible with agonism of 5-HT2A Rs. Our results provide insight into the potential therapeutic action of 5-HT2A R agonists for alcohol abuse.
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Affiliation(s)
| | | | | | | | - Alexey Ostroumov
- Co-corresponding authors: Alexey Ostroumov, Ph.D., Georgetown University, Department of Pharmacology and Physiology, New Research Building, Room W226, 3970 Reservoir Road, N.W., Washington D.C. 20057, USA, Phone: (832) 641-5562, , John A. Dani, Ph.D., University of Pennsylvania, Department of Neuroscience, Clinical Research Building, Room 211, 415 Curie Boulevard, Philadelphia, P.A. 19104, USA, Phone: (215) 898-8498,
| | - John A. Dani
- Co-corresponding authors: Alexey Ostroumov, Ph.D., Georgetown University, Department of Pharmacology and Physiology, New Research Building, Room W226, 3970 Reservoir Road, N.W., Washington D.C. 20057, USA, Phone: (832) 641-5562, , John A. Dani, Ph.D., University of Pennsylvania, Department of Neuroscience, Clinical Research Building, Room 211, 415 Curie Boulevard, Philadelphia, P.A. 19104, USA, Phone: (215) 898-8498,
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10
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Shimizu-Okabe C, Okada S, Okamoto S, Masuzaki H, Takayama C. Specific Expression of KCC2 in the α Cells of Normal and Type 1 Diabetes Model Mouse Pancreatic Islets. Acta Histochem Cytochem 2022; 55:47-56. [PMID: 35444351 PMCID: PMC8913275 DOI: 10.1267/ahc.21-00078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 12/22/2021] [Indexed: 01/14/2023] Open
Abstract
Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter in the mature brain; however, it acts excitatory during development. This difference in action depends on the intracellular chloride ion concentration, primarily regulated by potassium chloride co-transporter2 (KCC2). Sufficient KCC2 expression results in its inhibitory action. GABA is also abundant in pancreatic islets, where it acts differentially on the islet cells, and is involved in carbohydrate metabolism. However, the mechanisms underlying the differential action remain unknown. We performed immunohistochemistry for glutamic acid decarboxylase (GAD), a synthetic enzyme for GABA, and KCC2 in normal adult islets. GAD was co-localized with insulin in β cells, whereas KCC2 was expressed in glucagon-positive α cells. These results are in line with previous observations that GABA decreases glucagon release but increases insulin release, and suggest that GABA and insulin may work together in reducing blood glucose levels under hyperglycemia. Next, we examined the streptozotocin-induced type1 diabetes mellitus mouse model. GAD and insulin expression levels were markedly decreased. KCC2 was expressed in glucagon-positive cells, whereas insulin- and somatostatin-positive cells were KCC2-negative. These findings suggest that in diabetes model, reduced GABA release may cause disinhibition of glucagon release, resulting in increased blood sugar levels and the maintenance of hyperglycemic state.
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Affiliation(s)
| | - Shigeki Okada
- Department of Molecular Anatomy, School of Medicine, University of the Ryukyus
| | - Shiki Okamoto
- Division of Endocrinology, Diabetes and Metabolism, Hematology, Rheumatology School of Medicine, University of the Ryukyus
| | - Hiroaki Masuzaki
- Division of Endocrinology, Diabetes and Metabolism, Hematology, Rheumatology School of Medicine, University of the Ryukyus
| | - Chitoshi Takayama
- Department of Molecular Anatomy, School of Medicine, University of the Ryukyus
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11
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Shimizu-Okabe C, Kobayashi S, Kim J, Kosaka Y, Sunagawa M, Okabe A, Takayama C. Developmental Formation of the GABAergic and Glycinergic Networks in the Mouse Spinal Cord. Int J Mol Sci 2022; 23:ijms23020834. [PMID: 35055019 PMCID: PMC8776010 DOI: 10.3390/ijms23020834] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 01/07/2022] [Accepted: 01/11/2022] [Indexed: 12/15/2022] Open
Abstract
Gamma-aminobutyric acid (GABA) and glycine act as inhibitory neurotransmitters. Three types of inhibitory neurons and terminals, GABAergic, GABA/glycine coreleasing, and glycinergic, are orchestrated in the spinal cord neural circuits and play critical roles in regulating pain, locomotive movement, and respiratory rhythms. In this study, we first describe GABAergic and glycinergic transmission and inhibitory networks, consisting of three types of terminals in the mature mouse spinal cord. Second, we describe the developmental formation of GABAergic and glycinergic networks, with a specific focus on the differentiation of neurons, formation of synapses, maturation of removal systems, and changes in their action. GABAergic and glycinergic neurons are derived from the same domains of the ventricular zone. Initially, GABAergic neurons are differentiated, and their axons form synapses. Some of these neurons remain GABAergic in lamina I and II. Many GABAergic neurons convert to a coreleasing state. The coreleasing neurons and terminals remain in the dorsal horn, whereas many ultimately become glycinergic in the ventral horn. During the development of terminals and the transformation from radial glia to astrocytes, GABA and glycine receptor subunit compositions markedly change, removal systems mature, and GABAergic and glycinergic action shifts from excitatory to inhibitory.
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Affiliation(s)
- Chigusa Shimizu-Okabe
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan; (C.S.-O.); (S.K.); (Y.K.); (M.S.)
| | - Shiori Kobayashi
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan; (C.S.-O.); (S.K.); (Y.K.); (M.S.)
| | - Jeongtae Kim
- Department of Anatomy, Kosin University College of Medicine, Busan 49267, Korea;
| | - Yoshinori Kosaka
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan; (C.S.-O.); (S.K.); (Y.K.); (M.S.)
| | - Masanobu Sunagawa
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan; (C.S.-O.); (S.K.); (Y.K.); (M.S.)
| | - Akihito Okabe
- Department of Nutritional Science, Faculty of Health and Welfare, Seinan Jo Gakuin University, Fukuoka 803-0835, Japan;
| | - Chitoshi Takayama
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan; (C.S.-O.); (S.K.); (Y.K.); (M.S.)
- Correspondence: ; Tel.: +81-98-895-1103 or +81-895-1405
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12
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Branchereau P, Cattaert D. Chloride Homeostasis in Developing Motoneurons. ADVANCES IN NEUROBIOLOGY 2022; 28:45-61. [PMID: 36066820 DOI: 10.1007/978-3-031-07167-6_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Maturation of GABA/Glycine chloride-mediated synaptic inhibitions is crucial for the establishment of a balance between excitation and inhibition. GABA and glycine are excitatory neurotransmitters on immature neurons that exhibit elevated [Cl-]i. Later in development [Cl-]i drops leading to the occurrence of inhibitory synaptic activity. This ontogenic change is closely correlated to a differential expression of two cation-chloride cotransporters that are the Cl- channel K+/Cl- co-transporter type 2 (KCC2) that extrudes Cl- ions and the Na+-K+-2Cl- cotransporter NKCC1 that accumulates Cl- ions. The classical scheme built from studies performed on cortical and hippocampal networks proposes that immature neurons display high [Cl-]i because NKCC1 is overexpressed compared to KCC2 and that the co-transporters ratio reverses in mature neurons, lowering [Cl-]i. In this chapter, we will see that this classical scheme is not true in motoneurons (MNs) and that an early alteration of the chloride homeostasis may be involved in pathological conditions.
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Affiliation(s)
- Pascal Branchereau
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (INCIA), Univ. Bordeaux, UMR 5287, CNRS, Bordeaux, France.
| | - Daniel Cattaert
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (INCIA), Univ. Bordeaux, UMR 5287, CNRS, Bordeaux, France
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13
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Asraf H, Bogdanovic M, Gottesman N, Sekler I, Aizenman E, Hershfinkel M. SNAP23 regulates KCC2 membrane insertion and activity following mZnR/GPR39 activation in hippocampal neurons. iScience 2022; 25:103751. [PMID: 35118363 PMCID: PMC8800107 DOI: 10.1016/j.isci.2022.103751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/25/2021] [Accepted: 01/06/2022] [Indexed: 11/23/2022] Open
Abstract
Modulation of the neuronal K+/Cl− cotransporter 2 (KCC2) activity, which mediates Cl− export, is critical to neuronal function. Here, we demonstrate that KCC2 interacts with the SNARE protein synaptosome-associated protein 23, SNAP23, an essential component of membrane insertion machinery. Using KCC2 truncated mutants, we show that KCC2 C-terminal domain is essential for membrane targeting and SNAP23-dependent upregulation of KCC2 activity triggered by activation of the Zn2+-sensitive receptor mZnR/GPR39 in HEK293 cells. Expression of SNAP23 phosphorylation-insensitive mutants or inhibition of its upstream activator IκB kinase (IKK) prevents mZnR/GPR39 upregulation of KCC2 activity in mouse hippocampal neurons. We further find that SNAP23 interacts with Syntaxin 1A and KCC2, and that all three proteins exhibit increased membrane insertion following mZnR/GPR39 activation in neurons. Our results elucidate a G-protein-coupled receptor-dependent pathway for regulation of KCC activity, mediated via interaction with SNARE proteins. Neuronal K+/Cl− cotransporter 2 (KCC2) is regulated via interaction with SNAP23 Zn2+ enhances interaction and membrane insertion of SNAP23, Syntaxin 1A, and KCC2 Zn2+-dependent mZnR/GPR39 regulation of KCC2 requires SNAP23 phosphorylation Epithelial KCC3 regulation by ZnR/GPR39 also requires SNAP23
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14
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Ponomareva D, Petukhova E, Bregestovski P. Simultaneous Monitoring of pH and Chloride (Cl -) in Brain Slices of Transgenic Mice. Int J Mol Sci 2021; 22:13601. [PMID: 34948398 PMCID: PMC8708776 DOI: 10.3390/ijms222413601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 11/16/2022] Open
Abstract
Optosensorics is the direction of research possessing the possibility of non-invasive monitoring of the concentration of intracellular ions or activity of intracellular components using specific biosensors. In recent years, genetically encoded proteins have been used as effective optosensory means. These probes possess fluorophore groups capable of changing fluorescence when interacting with certain ions or molecules. For monitoring of intracellular concentrations of chloride ([Cl-]i) and hydrogen ([H+] i) the construct, called ClopHensor, which consists of a H+- and Cl--sensitive variant of the enhanced green fluorescent protein (E2GFP) fused with a monomeric red fluorescent protein (mDsRed) has been proposed. We recently developed a line of transgenic mice expressing ClopHensor in neurons and obtained the map of its expression in different areas of the brain. The purpose of this study was to examine the effectiveness of transgenic mice expressing ClopHensor for estimation of [H+]i and [Cl-]i concentrations in neurons of brain slices. We performed simultaneous monitoring of [H+]i and [Cl-]i under different experimental conditions including changing of external concentrations of ions (Ca2+, Cl-, K+, Na+) and synaptic stimulation of Shaffer's collaterals of hippocampal slices. The results obtained illuminate different pathways of regulation of Cl- and pH equilibrium in neurons and demonstrate that transgenic mice expressing ClopHensor represent a reliable tool for non-invasive simultaneous monitoring of intracellular Cl- and pH.
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Affiliation(s)
- Daria Ponomareva
- Institut de Neurosciences des Systèmes, Aix-Marseille University, INSERM, INS, 13005 Marseille, France;
- Institute of Neurosciences, Kazan State Medical University, 420111 Kazan, Russia;
- Department of Normal Physiology, Kazan State Medical University, 420111 Kazan, Russia
| | - Elena Petukhova
- Institute of Neurosciences, Kazan State Medical University, 420111 Kazan, Russia;
- Department of Normal Physiology, Kazan State Medical University, 420111 Kazan, Russia
| | - Piotr Bregestovski
- Institut de Neurosciences des Systèmes, Aix-Marseille University, INSERM, INS, 13005 Marseille, France;
- Institute of Neurosciences, Kazan State Medical University, 420111 Kazan, Russia;
- Department of Normal Physiology, Kazan State Medical University, 420111 Kazan, Russia
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15
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Farmer GE, Little JT, Marciante AB, Cunningham JT. AT1a-dependent GABA A inhibition in the MnPO following chronic intermittent hypoxia. Am J Physiol Regul Integr Comp Physiol 2021; 321:R469-R481. [PMID: 34189959 PMCID: PMC8530756 DOI: 10.1152/ajpregu.00030.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 06/24/2021] [Accepted: 06/29/2021] [Indexed: 11/22/2022]
Abstract
Chronic intermittent hypoxia (CIH) is associated with diurnal hypertension, increased sympathetic nerve activity (SNA), and increases in circulating angiotensin II (ANG II). In rats, CIH increases angiotensin type 1 (AT1a) receptor expression in the median preoptic nucleus (MnPO), and pharmacological blockade or viral knockdown of this receptor prevents CIH-dependent increases in diurnal blood pressure. The current study investigates the role of AT1a receptor in modulating the activity of MnPO neurons following 7 days of CIH. Male Sprague-Dawley rats received MnPO injections of an adeno-associated virus with an shRNA against the AT1a receptor or a scrambled control. Rats were then exposed to CIH for 8 h a day for 7 days. In vitro, loose patch recordings of spontaneous action potential activity were made from labeled MnPO neurons in response to brief focal application of ANG II or the GABAA receptor agonist muscimol. In addition, MnPO K-Cl cotransporter isoform 2 (KCC2) protein expression was assessed using Western blot. CIH impaired the duration but not the magnitude of ANG II-mediated excitation in the MnPO. Both CIH and AT1a knockdown also impaired GABAA-mediated inhibition, and CIH with AT1a knockdown produced GABAA-mediated excitation. Recordings using the ratiometric Cl- indicator ClopHensorN showed CIH was associated with Cl- efflux in MnPO neurons that was associated with decreased KCC2 phosphorylation. The combination of CIH and AT1a knockdown attenuated reduced KCC2 phosphorylation seen with CIH alone. The current study shows that CIH, through the activity of AT1a receptors, can impair GABAA-mediated inhibition in the MnPO and contribute to sustained hypertension.
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Affiliation(s)
- George E Farmer
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Joel T Little
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Alexandria B Marciante
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
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16
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Kim HY, Suh PG, Kim JI. The Role of Phospholipase C in GABAergic Inhibition and Its Relevance to Epilepsy. Int J Mol Sci 2021; 22:ijms22063149. [PMID: 33808762 PMCID: PMC8003358 DOI: 10.3390/ijms22063149] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 03/02/2021] [Accepted: 03/17/2021] [Indexed: 12/13/2022] Open
Abstract
Epilepsy is characterized by recurrent seizures due to abnormal hyperexcitation of neurons. Recent studies have suggested that the imbalance of excitation and inhibition (E/I) in the central nervous system is closely implicated in the etiology of epilepsy. In the brain, GABA is a major inhibitory neurotransmitter and plays a pivotal role in maintaining E/I balance. As such, altered GABAergic inhibition can lead to severe E/I imbalance, consequently resulting in excessive and hypersynchronous neuronal activity as in epilepsy. Phospholipase C (PLC) is a key enzyme in the intracellular signaling pathway and regulates various neuronal functions including neuronal development, synaptic transmission, and plasticity in the brain. Accumulating evidence suggests that neuronal PLC is critically involved in multiple aspects of GABAergic functions. Therefore, a better understanding of mechanisms by which neuronal PLC regulates GABAergic inhibition is necessary for revealing an unrecognized linkage between PLC and epilepsy and developing more effective treatments for epilepsy. Here we review the function of PLC in GABAergic inhibition in the brain and discuss a pathophysiological relationship between PLC and epilepsy.
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Affiliation(s)
- Hye Yun Kim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea; (H.Y.K.); (P.-G.S.)
| | - Pann-Ghill Suh
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea; (H.Y.K.); (P.-G.S.)
- Korea Brain Research Institute (KBRI), Daegu 41062, Korea
| | - Jae-Ick Kim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea; (H.Y.K.); (P.-G.S.)
- Correspondence: ; Tel.: +82-52-217-2458
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17
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Kitayama T. The Role of Astrocytes in the Modulation ofK +-Cl --Cotransporter-2 Function. Int J Mol Sci 2020; 21:E9539. [PMID: 33333849 PMCID: PMC7765297 DOI: 10.3390/ijms21249539] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/10/2020] [Accepted: 12/13/2020] [Indexed: 11/21/2022] Open
Abstract
Neuropathic pain is characterized by spontaneous pain, pain sensations, and tactile allodynia. The pain sensory system normally functions under a fine balance between excitation and inhibition. Neuropathic pain arises when this balance is lost for some reason. In past reports, various mechanisms of neuropathic pain development have been reported, one of which is the downregulation of K+-Cl--cotransporter-2 (KCC2) expression. In fact, various neuropathic pain models indicate a decrease in KCC2 expression. This decrease in KCC2 expression is often due to a brain-derived neurotrophic factor that is released from microglia. However, a similar reaction has been reported in astrocytes, and it is unclear whether astrocytes or microglia are more important. This review discusses the hypothesis that astrocytes have a crucial influence on the alteration of KCC2 expression.
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Affiliation(s)
- Tomoya Kitayama
- School of Pharmacy and Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
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18
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Phillips RS, Rosner I, Gittis AH, Rubin JE. The effects of chloride dynamics on substantia nigra pars reticulata responses to pallidal and striatal inputs. eLife 2020; 9:e55592. [PMID: 32894224 PMCID: PMC7476764 DOI: 10.7554/elife.55592] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 08/14/2020] [Indexed: 11/20/2022] Open
Abstract
As a rodent basal ganglia (BG) output nucleus, the substantia nigra pars reticulata (SNr) is well positioned to impact behavior. SNr neurons receive GABAergic inputs from the striatum (direct pathway) and globus pallidus (GPe, indirect pathway). Dominant theories of action selection rely on these pathways' inhibitory actions. Yet, experimental results on SNr responses to these inputs are limited and include excitatory effects. Our study combines experimental and computational work to characterize, explain, and make predictions about these pathways. We observe diverse SNr responses to stimulation of SNr-projecting striatal and GPe neurons, including biphasic and excitatory effects, which our modeling shows can be explained by intracellular chloride processing. Our work predicts that ongoing GPe activity could tune the SNr operating mode, including its responses in decision-making scenarios, and GPe output may modulate synchrony and low-frequency oscillations of SNr neurons, which we confirm using optogenetic stimulation of GPe terminals within the SNr.
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Affiliation(s)
- Ryan S Phillips
- Department of Mathematics, University of PittsburghPittsburghUnited States
- Center for the Neural Basis of CognitionPittsburghUnited States
| | - Ian Rosner
- Center for the Neural Basis of CognitionPittsburghUnited States
- Department of Biological Sciences, Carnegie Mellon UniversityPittsburghUnited States
| | - Aryn H Gittis
- Center for the Neural Basis of CognitionPittsburghUnited States
- Department of Biological Sciences, Carnegie Mellon UniversityPittsburghUnited States
| | - Jonathan E Rubin
- Department of Mathematics, University of PittsburghPittsburghUnited States
- Center for the Neural Basis of CognitionPittsburghUnited States
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19
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Martínez-Rojas VA, Jiménez-Garduño AM, Michelatti D, Tosatto L, Marchioretto M, Arosio D, Basso M, Pennuto M, Musio C. ClC-2-like Chloride Current Alterations in a Cell Model of Spinal and Bulbar Muscular Atrophy, a Polyglutamine Disease. J Mol Neurosci 2020; 71:662-674. [PMID: 32856205 DOI: 10.1007/s12031-020-01687-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 08/14/2020] [Indexed: 12/21/2022]
Abstract
Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by expansions of a polyglutamine (polyQ) tract in the androgen receptor (AR) gene. SBMA is associated with the progressive loss of lower motor neurons, together with muscle weakness and atrophy. PolyQ-AR is converted to a toxic species upon binding to its natural ligands, testosterone, and dihydrotestosterone (DHT). Our previous patch-clamp studies on a motor neuron-derived cell model of SBMA showed alterations in voltage-gated ion currents. Here, we identified and characterized chloride currents most likely belonging to the chloride channel-2 (ClC-2) subfamily, which showed significantly increased amplitudes in the SBMA cells. The treatment with the pituitary adenylyl cyclase-activating polypeptide (PACAP), a neuropeptide with a proven protective effect in a mouse model of SBMA, recovered chloride channel current alterations in SBMA cells. These observations suggest that the CIC-2 currents are affected in SBMA, an alteration that may contribute and potentially determine the pathophysiology of the disease.
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Affiliation(s)
- Vladimir A Martínez-Rojas
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy
| | - Aura M Jiménez-Garduño
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy.,Departamento de Ciencias de la Salud, Escuela de Ciencias, Universidad de las Américas Puebla (UDLAP), San Andrés Cholula, Puebla, Mexico
| | - Daniela Michelatti
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy.,CIBIO Department, Laboratory of Chromatin Biology and Epigenetics, University of Trento, Trento, Italy
| | - Laura Tosatto
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy
| | - Marta Marchioretto
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy
| | - Daniele Arosio
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy
| | - Manuela Basso
- CIBIO Department, Laboratory of Transcriptional Neurobiology, University of Trento, Trento, Italy
| | - Maria Pennuto
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,Padova Neuroscience Center (PNC), University of Padova, Padova, Italy.,Veneto Institute of Molecular Medicine, Padova, Italy
| | - Carlo Musio
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy.
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20
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Kosaka Y, Yafuso T, Shimizu-Okabe C, Kim J, Kobayashi S, Okura N, Ando H, Okabe A, Takayama C. Development and persistence of neuropathic pain through microglial activation and KCC2 decreasing after mouse tibial nerve injury. Brain Res 2020; 1733:146718. [PMID: 32045595 DOI: 10.1016/j.brainres.2020.146718] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 01/27/2020] [Accepted: 02/07/2020] [Indexed: 12/20/2022]
Abstract
Gamma-amino butyric acid (GABA) is an inhibitory neurotransmitter in the mature brain, but is excitatory during development and after motor nerve injury. This difference in GABAergic action depends on the intracellular chloride ion concentration ([Cl-]i), primarily regulated by potassium chloride co-transporter 2 (KCC2). To reveal precise processes of the neuropathic pain through changes in GABAergic action, we prepared tibial nerve ligation and severance models using male mice, and examined temporal relationships amongst changes in (1) the mechanical withdrawal threshold in the sural nerve area, (2) localization of the molecules involved in GABAergic transmission and its upstream signaling in the dorsal horn, and (3) histology of the tibial nerve. In the ligation model, tibial nerve degeneration disappeared by day 56, but mechanical allodynia, reduced KCC2 localization, and increased microglia density remained until day 90. Microglia density was higher in the tibial zone than the sural zone before day 21, but this result was inverted after day 28. In contrast, in the severance model, all above changes were detected until day 28, but were simultaneously and significantly recovered by day 90. These results suggested that in male mice, allodynia may be caused by reduced GABAergic synaptic inhibition, resulting from elevated [Cl-]i after the reduction of KCC2 by activated microglia. Furthermore, our results suggested that factors from degenerating nerve terminals may diffuse into the sural zone, whereby they induced the development of allodynia in the sural nerve area, while other factors in the sural zone may mediate persistent allodynia through the same pathway.
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Affiliation(s)
- Yoshinori Kosaka
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara 207, Nishihara, Okinawa 9030215, Japan
| | - Tsukasa Yafuso
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara 207, Nishihara, Okinawa 9030215, Japan
| | - Chigusa Shimizu-Okabe
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara 207, Nishihara, Okinawa 9030215, Japan
| | - Jeongtae Kim
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara 207, Nishihara, Okinawa 9030215, Japan; Department of Veterinary Anatomy, College of Veterinary Medicine, Jeju National University, Jeju 63243, Republic of Korea
| | - Shiori Kobayashi
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara 207, Nishihara, Okinawa 9030215, Japan
| | - Nobuhiko Okura
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara 207, Nishihara, Okinawa 9030215, Japan
| | - Hironobu Ando
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara 207, Nishihara, Okinawa 9030215, Japan
| | - Akihito Okabe
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara 207, Nishihara, Okinawa 9030215, Japan; Department of Nutritional Science, Faculty of Health and Welfare, Seinan Jo Gakuin University, Fukuoka 803-0835, Japan
| | - Chitoshi Takayama
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, 207 Uehara 207, Nishihara, Okinawa 9030215, Japan.
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21
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Zajac M, Chakraborty K, Saha S, Mahadevan V, Infield DT, Accardi A, Qiu Z, Krishnan Y. What biologists want from their chloride reporters – a conversation between chemists and biologists. J Cell Sci 2020; 133:133/2/jcs240390. [DOI: 10.1242/jcs.240390] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
ABSTRACT
Impaired chloride transport affects diverse processes ranging from neuron excitability to water secretion, which underlie epilepsy and cystic fibrosis, respectively. The ability to image chloride fluxes with fluorescent probes has been essential for the investigation of the roles of chloride channels and transporters in health and disease. Therefore, developing effective fluorescent chloride reporters is critical to characterizing chloride transporters and discovering new ones. However, each chloride channel or transporter has a unique functional context that demands a suite of chloride probes with appropriate sensing characteristics. This Review seeks to juxtapose the biology of chloride transport with the chemistries underlying chloride sensors by exploring the various biological roles of chloride and highlighting the insights delivered by studies using chloride reporters. We then delineate the evolution of small-molecule sensors and genetically encoded chloride reporters. Finally, we analyze discussions with chloride biologists to identify the advantages and limitations of sensors in each biological context, as well as to recognize the key design challenges that must be overcome for developing the next generation of chloride sensors.
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Affiliation(s)
- Matthew Zajac
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
- Grossman Institute of Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL 60637, USA
| | - Kasturi Chakraborty
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
- Grossman Institute of Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL 60637, USA
- Ben May Department for Cancer Research, The University of Chicago, Chicago, IL 60637, USA
| | - Sonali Saha
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
| | - Vivek Mahadevan
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Daniel T. Infield
- Department of Molecular Physiology and Biophysics, The University of Iowa, Iowa City, IA 52242, USA
| | - Alessio Accardi
- Department of Anesthesiology, Weill Cornell Medical School, New York, NY 10065, USA
- Department of Physiology and Biophysics, Weill Cornell Medical School, New York, NY 10065, USA
- Department of Biochemistry, Weill Cornell Medical School, New York, NY 10065, USA
| | - Zhaozhu Qiu
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21218, USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21218, USA
| | - Yamuna Krishnan
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
- Grossman Institute of Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL 60637, USA
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5-HT 2A receptor activation normalizes stress-induced dysregulation of GABAergic signaling in the ventral tegmental area. Proc Natl Acad Sci U S A 2019; 116:27028-27034. [PMID: 31806759 DOI: 10.1073/pnas.1911446116] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Stress is known to alter GABAergic signaling in the ventral tegmental area (VTA), and this inhibitory plasticity is associated with increased alcohol self-administration. In humans, serotonin 2A receptor (5-HT2AR) agonists can treat stress- and alcohol-related disorders, but the neural substrates are ill-defined. Thus, we reasoned that 5-HT2AR pharmacotherapies may ameliorate the stress-induced dysregulated inhibitory VTA circuitry that contributes to subsequent alcohol abuse. We found that acute stress exposure in mice compromised GABA-mediated inhibition of VTA GABA neurons corresponding with increased ethanol-induced GABAergic transmission. This stress-induced inhibitory plasticity was reversible by applying the 5-HT2AR agonist TCB-2 ex vivo via functional enhancement of the potassium-chloride cotransporter KCC2. The signaling pathway linking 5-HT2AR activation and normalization of KCC2 function was dependent on protein kinase C signaling and phosphorylation of KCC2 at serine 940 (S940), as mutation of S940 to alanine prevented restoration of chloride transport function by TCB-2. Through positive modulation of KCC2, TCB-2 also reduced elevated ethanol-induced GABAergic signaling after stress exposure that has previously been linked to increased ethanol consumption. Collectively, these findings provide mechanistic insights into the therapeutic action of 5-HT2AR agonists at the neuronal and circuit levels of brain reward circuitry.
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Moore YE, Conway LC, Wobst HJ, Brandon NJ, Deeb TZ, Moss SJ. Developmental Regulation of KCC2 Phosphorylation Has Long-Term Impacts on Cognitive Function. Front Mol Neurosci 2019; 12:173. [PMID: 31396048 PMCID: PMC6664008 DOI: 10.3389/fnmol.2019.00173] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 07/01/2019] [Indexed: 01/04/2023] Open
Abstract
GABAA receptor-mediated currents shift from excitatory to inhibitory during postnatal brain development in rodents. A postnatal increase in KCC2 protein expression is considered to be the sole mechanism controlling the developmental onset of hyperpolarizing synaptic transmission, but here we identify a key role for KCC2 phosphorylation in the developmental EGABA shift. Preventing phosphorylation of KCC2 in vivo at either residue serine 940 (S940), or at residues threonine 906 and threonine 1007 (T906/T1007), delayed or accelerated the postnatal onset of KCC2 function, respectively. Several models of neurodevelopmental disorders including Rett syndrome, Fragile × and Down's syndrome exhibit delayed postnatal onset of hyperpolarizing GABAergic inhibition, but whether the timing of the onset of hyperpolarizing synaptic inhibition during development plays a role in establishing adulthood cognitive function is unknown; we have used the distinct KCC2-S940A and KCC2-T906A/T1007A knock-in mouse models to address this issue. Altering KCC2 function resulted in long-term abnormalities in social behavior and memory retention. Tight regulation of KCC2 phosphorylation is therefore required for the typical timing of the developmental onset of hyperpolarizing synaptic inhibition, and it plays a fundamental role in the regulation of adulthood cognitive function.
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Affiliation(s)
- Yvonne E. Moore
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Leslie C. Conway
- AstraZeneca-Tufts University Laboratory for Basic and Translational Neuroscience Research, Tufts University School of Medicine, Boston, MA, United States
| | - Heike J. Wobst
- Neuroscience, R&D Biopharmaceuticals, AstraZeneca, Boston, MA, United States
| | - Nicholas J. Brandon
- Neuroscience, R&D Biopharmaceuticals, AstraZeneca, Boston, MA, United States
| | - Tarek Z. Deeb
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Stephen J. Moss
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
- AstraZeneca-Tufts University Laboratory for Basic and Translational Neuroscience Research, Tufts University School of Medicine, Boston, MA, United States
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
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Goutierre M, Al Awabdh S, Donneger F, François E, Gomez-Dominguez D, Irinopoulou T, Menendez de la Prida L, Poncer JC. KCC2 Regulates Neuronal Excitability and Hippocampal Activity via Interaction with Task-3 Channels. Cell Rep 2019; 28:91-103.e7. [PMID: 31269453 DOI: 10.1016/j.celrep.2019.06.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 04/18/2019] [Accepted: 05/30/2019] [Indexed: 10/26/2022] Open
Abstract
KCC2 regulates neuronal transmembrane chloride gradients and thereby controls GABA signaling in the brain. KCC2 downregulation is observed in numerous neurological and psychiatric disorders. Paradoxical, excitatory GABA signaling is usually assumed to contribute to abnormal network activity underlying the pathology. We tested this hypothesis and explored the functional impact of chronic KCC2 downregulation in the rat dentate gyrus. Although the reversal potential of GABAA receptor currents is depolarized in KCC2 knockdown neurons, this shift is compensated by depolarization of the resting membrane potential. This reflects downregulation of leak potassium currents. We show KCC2 interacts with Task-3 (KCNK9) channels and is required for their membrane expression. Increased neuronal excitability upon KCC2 suppression altered dentate gyrus rhythmogenesis, which could be normalized by chemogenetic hyperpolarization. Our data reveal KCC2 downregulation engages complex synaptic and cellular alterations beyond GABA signaling that perturb network activity thus offering additional targets for therapeutic intervention.
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Affiliation(s)
- Marie Goutierre
- INSERM UMR-S 1270, 75005 Paris, France; Sorbonne Université, 75005 Paris, France; Institut du Fer à Moulin, 75005 Paris, France
| | - Sana Al Awabdh
- INSERM UMR-S 1270, 75005 Paris, France; Sorbonne Université, 75005 Paris, France; Institut du Fer à Moulin, 75005 Paris, France
| | - Florian Donneger
- INSERM UMR-S 1270, 75005 Paris, France; Sorbonne Université, 75005 Paris, France; Institut du Fer à Moulin, 75005 Paris, France
| | - Emeline François
- INSERM UMR-S 1270, 75005 Paris, France; Sorbonne Université, 75005 Paris, France; Institut du Fer à Moulin, 75005 Paris, France
| | - Daniel Gomez-Dominguez
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid 28002, Spain
| | - Theano Irinopoulou
- INSERM UMR-S 1270, 75005 Paris, France; Sorbonne Université, 75005 Paris, France; Institut du Fer à Moulin, 75005 Paris, France
| | | | - Jean Christophe Poncer
- INSERM UMR-S 1270, 75005 Paris, France; Sorbonne Université, 75005 Paris, France; Institut du Fer à Moulin, 75005 Paris, France.
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25
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Garand D, Mahadevan V, Woodin MA. Ionotropic and metabotropic kainate receptor signalling regulates Cl - homeostasis and GABAergic inhibition. J Physiol 2019; 597:1677-1690. [PMID: 30570751 PMCID: PMC6418771 DOI: 10.1113/jp276901] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 12/19/2018] [Indexed: 12/28/2022] Open
Abstract
KEY POINTS Potassium-chloride co-transporter 2 (KCC2) plays a critical role in regulating chloride homeostasis, which is essential for hyperpolarizing inhibition in the mature nervous system. KCC2 interacts with many proteins involved in excitatory neurotransmission, including the GluK2 subunit of the kainate receptor (KAR). We show that activation of KARs hyperpolarizes the reversal potential for GABA (EGABA ) via both ionotropic and metabotropic signalling mechanisms. KCC2 is required for the metabotropic KAR-mediated regulation of EGABA , although ionotropic KAR signalling can hyperpolarize EGABA independent of KCC2 transporter function. The KAR-mediated hyperpolarization of EGABA is absent in the GluK1/2-/- mouse and is independent of zinc release from mossy fibre terminals. The ability of KARs to regulate KCC2 function may have implications in diseases with disrupted excitation: inhibition balance, such as epilepsy, neuropathic pain, autism spectrum disorders and Down's syndrome. ABSTRACT Potassium-chloride co-transporter 2 (KCC2) plays a critical role in the regulation of chloride (Cl- ) homeostasis within mature neurons. KCC2 is a secondarily active transporter that extrudes Cl- from the neuron, which maintains a low intracellular Cl- concentration [Cl- ]. This results in a hyperpolarized reversal potential of GABA (EGABA ), which is required for fast synaptic inhibition in the mature central nervous system. KCC2 also plays a structural role in dendritic spines and at excitatory synapses, and interacts with 'excitatory' proteins, including the GluK2 subunit of kainate receptors (KARs). KARs are glutamate receptors that display both ionotropic and metabotropic signalling. We show that activating KARs in the hippocampus hyperpolarizes EGABA , thus strengthening inhibition. This hyperpolarization occurs via both ionotropic and metabotropic KAR signalling in the CA3 region, whereas it is absent in the GluK1/2-/- mouse, and is independent of zinc release from mossy fibre terminals. The metabotropic signalling mechanism is dependent on KCC2, although the ionotropic signalling mechanism produces a hyperpolarization of EGABA even in the absence of KCC2 transporter function. These results demonstrate a novel functional interaction between a glutamate receptor and KCC2, a transporter critical for maintaining inhibition, suggesting that the KAR:KCC2 complex may play an important role in excitatory:inhibitory balance in the hippocampus. Additionally, the ability of KARs to regulate chloride homeostasis independently of KCC2 suggests that KAR signalling can regulate inhibition via multiple mechanisms. Activation of kainate-type glutamate receptors could serve as an important mechanism for increasing the strength of inhibition during periods of strong glutamatergic activity.
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MESH Headings
- Animals
- CA1 Region, Hippocampal/cytology
- CA1 Region, Hippocampal/metabolism
- CA1 Region, Hippocampal/physiology
- CA3 Region, Hippocampal/cytology
- CA3 Region, Hippocampal/metabolism
- CA3 Region, Hippocampal/physiology
- Cells, Cultured
- Chlorides/metabolism
- Female
- Homeostasis
- Inhibitory Postsynaptic Potentials
- Male
- Mice
- Mice, Inbred C57BL
- Mossy Fibers, Hippocampal/metabolism
- Mossy Fibers, Hippocampal/physiology
- Pyramidal Cells/metabolism
- Pyramidal Cells/physiology
- Receptors, GABA/metabolism
- Receptors, Kainic Acid/metabolism
- Symporters/metabolism
- K Cl- Cotransporters
- GluK2 Kainate Receptor
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Affiliation(s)
- Danielle Garand
- Department of Cell and Systems BiologyUniversity of TorontoTorontoONCanada
| | - Vivek Mahadevan
- Department of Cell and Systems BiologyUniversity of TorontoTorontoONCanada
| | - Melanie A. Woodin
- Department of Cell and Systems BiologyUniversity of TorontoTorontoONCanada
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26
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Farmer GE, Balapattabi K, Bachelor ME, Little JT, Cunningham JT. AT 1a influences GABAA-mediated inhibition through regulation of KCC2 expression. Am J Physiol Regul Integr Comp Physiol 2018; 315:R972-R982. [PMID: 30156863 PMCID: PMC6295501 DOI: 10.1152/ajpregu.00105.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 08/27/2018] [Accepted: 08/27/2018] [Indexed: 11/22/2022]
Abstract
The median preoptic nucleus (MnPO) is an integrative site involved in body fluid homeostasis, cardiovascular control, thermoregulation, and sleep homeostasis. Angiotensin II (ANG II), a neuropeptide shown to have excitatory effects on MnPO neurons, is of particular interest with regard to its role in body fluid homeostasis and cardiovascular control. The present study investigated the role of angiotensin type 1a (AT1a) receptor activation on neuronal excitability in the MnPO. Male Sprague-Dawley rats were infused with an adeno-associated virus with an shRNA against the AT1a receptor or a scrambled control. In vitro loose-patch voltage-clamp recordings of spontaneous action potential activity were made from labeled MnPO neurons in response to brief focal application of ANG II or the GABAA receptor agonist muscimol. Additionally, tissue punches from MnPO were taken to asses mRNA and protein expression. AT1a receptor knockdown neurons were insensitive to ANG II and showed a marked reduction in GABAA-mediated inhibition. The reduction in GABAA-mediated inhibition was not associated with reductions in mRNA or protein expression of GABAA β-subunits. Knockdown of the AT1a receptor was associated with a reduction in the potassium-chloride cotransporter KCC2 mRNA as well as a reduction in pS940 KCC2 protein. The impaired GABAA-mediated inhibition in AT1a knockdown neurons was recovered by bath application of phospholipase C and protein kinase C activators. The following study indicates that AT1a receptor activation mediates the excitability of MnPO neurons, in part, through the regulation of KCC2. The regulation of KCC2 influences the intracellular [Cl-] and the subsequent efficacy of GABAA-mediated currents.
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Affiliation(s)
- George E Farmer
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth , Fort Worth, Texas
| | - Kirthikaa Balapattabi
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth , Fort Worth, Texas
| | - Martha E Bachelor
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth , Fort Worth, Texas
| | - Joel T Little
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth , Fort Worth, Texas
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth , Fort Worth, Texas
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27
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Sánchez-Brualla I, Boulenguez P, Brocard C, Liabeuf S, Viallat-Lieutaud A, Navarro X, Udina E, Brocard F. Activation of 5-HT 2A Receptors Restores KCC2 Function and Reduces Neuropathic Pain after Spinal Cord Injury. Neuroscience 2018; 387:48-57. [PMID: 28844001 DOI: 10.1016/j.neuroscience.2017.08.033] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 07/26/2017] [Accepted: 08/14/2017] [Indexed: 11/30/2022]
Abstract
Downregulation of the potassium chloride cotransporter type 2 (KCC2) after a spinal cord injury (SCI) disinhibits motoneurons and dorsal horn interneurons causing spasticity and neuropathic pain, respectively. We showed recently (Bos et al., 2013) that specific activation of 5-HT2A receptors by TCB-2 [(4-bromo-3,6-dimethoxybenzocyclobuten-1-yl)methylamine hydrobromide] upregulates KCC2 function, restores motoneuronal inhibition and reduces SCI-induced spasticity. Here, we tested the potential analgesic effect of TCB-2 on central (thoracic hemisection) and peripheral [spared nerve injury (SNI)] neuropathic pain. We found mechanical and thermal hyperalgesia reduced by an acute administration of TCB-2 in rats with SCI. This analgesic effect was associated with an increase in dorsal horn membrane KCC2 expression and was prevented by pharmacological blockade of KCC2 with an intrathecal injection of DIOA [(dihydroindenyl)oxy]alkanoic acid]. In contrast, the SNI-induced neuropathic pain was not attenuated by TCB-2 although there was a slight increase of membrane KCC2 expression in the dorsal horn ipsilateral to the lesion. Up-regulation of KCC2 function by targeting 5-HT2A receptors, therefore, has therapeutic potential in the treatment of neuropathic pain induced by SCI but not by SNI.
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Affiliation(s)
- Irene Sánchez-Brualla
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS), Marseille, France; Department of Cell Biology, Physiology, and Immunology, Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas, Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Pascale Boulenguez
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS), Marseille, France
| | - Cécile Brocard
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS), Marseille, France
| | - Sylvie Liabeuf
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS), Marseille, France
| | - Annelise Viallat-Lieutaud
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS), Marseille, France
| | - Xavier Navarro
- Department of Cell Biology, Physiology, and Immunology, Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas, Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Esther Udina
- Department of Cell Biology, Physiology, and Immunology, Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas, Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Frédéric Brocard
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS), Marseille, France.
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28
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Wan L, Ren L, Chen L, Wang G, Liu X, Wang BH, Wang Y. M-Calpain Activation Facilitates Seizure Induced KCC2 Down Regulation. Front Mol Neurosci 2018; 11:287. [PMID: 30186110 PMCID: PMC6110871 DOI: 10.3389/fnmol.2018.00287] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 07/30/2018] [Indexed: 12/12/2022] Open
Abstract
Potassium chloride co-transporter 2 (KCC2), a major chloride transporter that maintains GABAA receptor inhibition in mature mammalian neurons, is down-regulated in the hippocampus during epileptogenesis. Impaired KCC2 function accelerates or facilitates seizure onset. Calpain, with two main subtypes of m- and μ-calpain, is a Ca2+-dependent cysteine protease that mediates the nonlysosomal degradation of KCC2. Although recent studies have demonstrated that calpain inhibitors exert antiepileptic and neuroprotective effects in animal models of acute and chronic epilepsy, whether calpain activation affects seizure induction through KCC2 degradation remains unknown. Our results showed that: (1) Blockade of calpain by non-selective calpain inhibitor MDL-28170 prevented convulsant stimulation induced KCC2 downregulation, and reduced the incidence and the severity of pentylenetetrazole (PTZ) induced seizures. (2) m-calpain, but not μ-calpain, inhibitor mimicked MDL-28170 effect on preventing KCC2 downregulation. (3) Phosphorylation of m-calpain has been significantly enhanced during seizure onset, which was partly mediated by the calcium independent MAPK/ERK signaling pathway activation. (4) MAPK/ERK signaling blockade also had similar effect as total calpain blockade on both KCC2 downregulation and animal seizure induction. The results indicate that upregulated m-calpain activation by MAPK/ERK during convulsant stimulation down regulates both cytoplasm- and membrane KCC2, and in turn facilitates seizure induction. This finding may provide a foundation for the development of highly effective antiepileptic drugs targeting of m-calpain.
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Affiliation(s)
- Li Wan
- Department of Neurology, Institutes of Brain Science & State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Liang Ren
- Department of Neurology, Institutes of Brain Science & State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Lulan Chen
- Department of Neurology, Institutes of Brain Science & State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Guoxiang Wang
- Department of Neurology, Institutes of Brain Science & State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Xu Liu
- Department of Neurology, Institutes of Brain Science & State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Benjamin H Wang
- Department of Neurology, Institutes of Brain Science & State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yun Wang
- Department of Neurology, Institutes of Brain Science & State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University, Shanghai, China
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29
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Carter BM, Sullivan BJ, Landers JR, Kadam SD. Dose-dependent reversal of KCC2 hypofunction and phenobarbital-resistant neonatal seizures by ANA12. Sci Rep 2018; 8:11987. [PMID: 30097625 PMCID: PMC6086916 DOI: 10.1038/s41598-018-30486-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 07/31/2018] [Indexed: 01/22/2023] Open
Abstract
Neonatal seizures have an incidence of 3.5 per 1000 newborns; while hypoxic-ischemic encephalopathy (HIE) accounts for 50-60% of cases, half are resistant to 1st-line anti-seizure drugs such as phenobarbital (PB). Tyrosine receptor kinase B (TrkB) activation following ischemic injury is known to increase neuronal excitability by downregulation of K-Cl co-transporter 2 (KCC2); a neuronal chloride (Cl-) co-transporter. In this study, three graded doses of ANA12, a small-molecule selective TrkB antagonist, were tested in CD1 mice at P7 and P10 following induction of neonatal ischemia by a unilateral carotid ligation. The PB loading dose remained the same in all treatment groups at both ages. Evaluation criteria for the anti-seizure efficacy of ANA12 were: (1) quantitative electroencephalographic (EEG) seizure burden and power, (2) rescue of post-ischemic KCC2 and pKCC2-S940 downregulation and (3) reversal of TrkB pathway activation following ischemia. ANA12 significantly rescued PB resistant seizures in a dose-dependent manner at P7 and improved PB efficacy at P10. Additionally, female pups responded better to lower doses of ANA12 compared to males. ANA12 significantly reversed post-ischemic KCC2 downregulation and TrkB pathway activation at P7 when PB alone was inefficacious. Rescuing KCC2 hypofunction may be critical for preventing emergence of refractory seizures.
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Affiliation(s)
- B M Carter
- Neuroscience Laboratory, Hugo Moser Research Institute at Kennedy Krieger, Baltimore, MD, USA
| | - B J Sullivan
- Neuroscience Laboratory, Hugo Moser Research Institute at Kennedy Krieger, Baltimore, MD, USA
| | - J R Landers
- Neuroscience Laboratory, Hugo Moser Research Institute at Kennedy Krieger, Baltimore, MD, USA
| | - S D Kadam
- Neuroscience Laboratory, Hugo Moser Research Institute at Kennedy Krieger, Baltimore, MD, USA.
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
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30
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Olde Engberink AHO, Meijer JH, Michel S. Chloride cotransporter KCC2 is essential for GABAergic inhibition in the SCN. Neuropharmacology 2018; 138:80-86. [PMID: 29782876 DOI: 10.1016/j.neuropharm.2018.05.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 04/26/2018] [Accepted: 05/17/2018] [Indexed: 12/31/2022]
Abstract
One of the principal neurotransmitters of the central nervous system is GABA. In the adult brain, GABA is predominantly inhibitory, but there is growing evidence indicating that GABA can shift to excitatory action depending on environmental conditions. In the mammalian central circadian clock of the suprachiasmatic nucleus (SCN) GABAergic activity shifts from inhibition to excitation when animals are exposed to long day photoperiod. The polarity of the GABAergic response (inhibitory versus excitatory) depends on the GABA equilibrium potential determined by the intracellular Cl- concentration ([Cl-]i). Chloride homeostasis can be regulated by Cl- cotransporters like NKCC1 and KCC2 in the membrane, but the mechanisms for maintaining [Cl-]i are still under debate. This study investigates the role of KCC2 on GABA-induced Ca2+ transients in SCN neurons from mice exposed to different photoperiods. We show for the first time that blocking KCC2 with the newly developed blocker ML077 can cause a shift in the polarity of the GABAergic response. This will increase the amount of excitatory responses in SCN neurons and thus cause a shift in excitatory/inhibitory ratio. These results indicate that KCC2 is an essential component in regulating [Cl-]i and the equilibrium potential of Cl- and thereby determining the sign of the GABAergic response. Moreover, our data suggest a role for the Cl- cotransporters in the switch from inhibition to excitation observed under long day photoperiod.
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Affiliation(s)
- A H O Olde Engberink
- Department of Cellular and Chemical Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, the Netherlands
| | - J H Meijer
- Department of Cellular and Chemical Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, the Netherlands
| | - S Michel
- Department of Cellular and Chemical Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, the Netherlands.
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31
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Klein PM, Lu AC, Harper ME, McKown HM, Morgan JD, Beenhakker MP. Tenuous Inhibitory GABAergic Signaling in the Reticular Thalamus. J Neurosci 2018; 38:1232-1248. [PMID: 29273603 PMCID: PMC5792478 DOI: 10.1523/jneurosci.1345-17.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 09/20/2017] [Accepted: 11/03/2017] [Indexed: 11/21/2022] Open
Abstract
Maintenance of a low intracellular Cl- concentration ([Cl-]i) is critical for enabling inhibitory neuronal responses to GABAA receptor-mediated signaling. Cl- transporters, including KCC2, and extracellular impermeant anions ([A]o) of the extracellular matrix are both proposed to be important regulators of [Cl-]i Neurons of the reticular thalamic (RT) nucleus express reduced levels of KCC2, indicating that GABAergic signaling may produce excitation in RT neurons. However, by performing perforated patch recordings and calcium imaging experiments in rats (male and female), we find that [Cl-]i remains relatively low in RT neurons. Although we identify a small contribution of [A]o to a low [Cl-]i in RT neurons, our results also demonstrate that reduced levels of KCC2 remain sufficient to maintain low levels of Cl- Reduced KCC2 levels, however, restrict the capacity of RT neurons to rapidly extrude Cl- following periods of elevated GABAergic signaling. In a computational model of a local RT network featuring slow Cl- extrusion kinetics, similar to those we found experimentally, model RT neurons are predisposed to an activity-dependent switch from GABA-mediated inhibition to excitation. By decreasing the activity threshold required to produce excitatory GABAergic signaling, weaker stimuli are able to propagate activity within the model RT nucleus. Our results indicate the importance of even diminished levels of KCC2 in maintaining inhibitory signaling within the RT nucleus and suggest how this important activity choke point may be easily overcome in disorders such as epilepsy.SIGNIFICANCE STATEMENT Precise regulation of intracellular Cl- levels ([Cl-]i) preserves appropriate, often inhibitory, GABAergic signaling within the brain. However, there is disagreement over the relative contribution of various mechanisms that maintain low [Cl-]i We found that the Cl- transporter KCC2 is an important Cl- extruder in the reticular thalamic (RT) nucleus, despite this nucleus having remarkably low KCC2 immunoreactivity relative to other regions of the adult brain. We also identified a smaller contribution of fixed, impermeant anions ([A]o) to lowering [Cl-]i in RT neurons. Inhibitory signaling among RT neurons is important for preventing excessive activation of RT neurons, which can be responsible for generating seizures. Our work suggests that KCC2 critically restricts the spread of activity within the RT nucleus.
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Affiliation(s)
- Peter M Klein
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22903
| | - Adam C Lu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22903
| | - Megan E Harper
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22903
| | - Hannah M McKown
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22903
| | - Jessica D Morgan
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22903
| | - Mark P Beenhakker
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22903
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Kitayama T. The Role of K +-Cl --Cotransporter-2 in Neuropathic Pain. Neurochem Res 2018; 43:110-115. [PMID: 28677029 DOI: 10.1007/s11064-017-2344-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Revised: 06/09/2017] [Accepted: 06/26/2017] [Indexed: 01/21/2023]
Abstract
The pain sensory system normally functions under a fine balance between excitation and inhibition. When this balance is perturbed for some reason, it leads to neuropathic pain. There is accumulating evidence that attributes this pain generation to specific dysfunctions of the inhibitory system in the spinal cord. One possible mechanism leading to the induction of these dysfunctions is the down-regulation of K+-Cl--cotransporter-2 (KCC2) expression. In fact, various neuropathic pain models indicate a decrease of KCC2 expression in the spinal cord. The alteration of KCC2 expression affects GABAergic and glycinergic neurotransmissions, because KCC2 is a potassium-chloride exporter and serves to maintain intracellular chloride concentration. When there is a low level of KCC2 expression, GABAergic and glycinergic neurotransmissions transform from inhibitory signals to excitatory signals. In this review, the hypothesis that an alteration of KCC2 expression has a crucial influence on the initiation/development or maintenance of neuropathic pain is discussed. In addition, it is suggested that the alteration of inhibitory signals is dependent on the time after peripheral nerve injury.
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Affiliation(s)
- Tomoya Kitayama
- Department of Pharmacy, School of Pharmacy and Pharmaceutical Science, Mukogawa Women's University, 11-68 Koshien-Kyubanmachi, Nishinomiya, Hyogo, 663-8179, Japan.
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Emerging Mechanisms Underlying Dynamics of GABAergic Synapses. J Neurosci 2017; 37:10792-10799. [PMID: 29118207 DOI: 10.1523/jneurosci.1824-17.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 09/25/2017] [Accepted: 10/11/2017] [Indexed: 11/21/2022] Open
Abstract
Inhibitory circuits are diverse, yet with a poorly understood cell biology. Functional characterization of distinct inhibitory neuron subtypes has not been sufficient to explain how GABAergic neurotransmission sculpts principal cell activity in a relevant fashion. Our Mini-Symposium brings together several emerging mechanisms that modulate GABAergic neurotransmission dynamically from either the presynaptic or the postsynaptic site. The first two talks discuss novel developmental and neuronal subtype-specific contributions to the excitatory/inhibitory balance and circuit maturation. The next three talks examine how interactions between cellular pathways, lateral diffusion of proteins between synapses, and chloride transporter function at excitatory and inhibitory synapses and facilitate inhibitory synapse adaptations. Finally, we address functional differences within GABAergic interneurons to highlight the importance of diverse, flexible, and versatile inputs that shape network function. Together, the selection of topics demonstrates how developmental and activity-dependent mechanisms coordinate inhibition in relation to the excitatory inputs and vice versa.
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Mahadevan V, Khademullah CS, Dargaei Z, Chevrier J, Uvarov P, Kwan J, Bagshaw RD, Pawson T, Emili A, De Koninck Y, Anggono V, Airaksinen M, Woodin MA. Native KCC2 interactome reveals PACSIN1 as a critical regulator of synaptic inhibition. eLife 2017; 6:e28270. [PMID: 29028184 PMCID: PMC5640428 DOI: 10.7554/elife.28270] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 09/08/2017] [Indexed: 01/01/2023] Open
Abstract
KCC2 is a neuron-specific K+-Cl- cotransporter essential for establishing the Cl- gradient required for hyperpolarizing inhibition in the central nervous system (CNS). KCC2 is highly localized to excitatory synapses where it regulates spine morphogenesis and AMPA receptor confinement. Aberrant KCC2 function contributes to human neurological disorders including epilepsy and neuropathic pain. Using functional proteomics, we identified the KCC2-interactome in the mouse brain to determine KCC2-protein interactions that regulate KCC2 function. Our analysis revealed that KCC2 interacts with diverse proteins, and its most predominant interactors play important roles in postsynaptic receptor recycling. The most abundant KCC2 interactor is a neuronal endocytic regulatory protein termed PACSIN1 (SYNDAPIN1). We verified the PACSIN1-KCC2 interaction biochemically and demonstrated that shRNA knockdown of PACSIN1 in hippocampal neurons increases KCC2 expression and hyperpolarizes the reversal potential for Cl-. Overall, our global native-KCC2 interactome and subsequent characterization revealed PACSIN1 as a novel and potent negative regulator of KCC2.
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Affiliation(s)
- Vivek Mahadevan
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | | | - Zahra Dargaei
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | - Jonah Chevrier
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | - Pavel Uvarov
- Department of Anatomy, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Julian Kwan
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular ResearchUniversity of TorontoTorontoCanada
| | - Richard D Bagshaw
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
| | - Tony Pawson
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
| | - Andrew Emili
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular ResearchUniversity of TorontoTorontoCanada
| | - Yves De Koninck
- Institut Universitaire en Santé Mentale de QuébecQuébecCanada
- Department of Psychiatry and NeuroscienceUniversité LavalQuébecCanada
| | - Victor Anggono
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia ResearchThe University of QueenslandBrisbaneAustralia
| | - Matti Airaksinen
- Department of Anatomy, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Melanie A Woodin
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
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Moore YE, Kelley MR, Brandon NJ, Deeb TZ, Moss SJ. Seizing Control of KCC2: A New Therapeutic Target for Epilepsy. Trends Neurosci 2017; 40:555-571. [PMID: 28803659 DOI: 10.1016/j.tins.2017.06.008] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 06/20/2017] [Accepted: 06/22/2017] [Indexed: 11/17/2022]
Abstract
Deficits in GABAergic inhibition result in the abnormal neuronal activation and synchronization that underlies seizures. However, the molecular mechanisms responsible for transforming a normal brain into an epileptic one remain largely unknown. Hyperpolarizing inhibition mediated by type A GABA (GABAA) receptors is dependent on chloride extrusion by the neuron-specific type 2K+-Cl- cotransporter (KCC2). Loss-of-function mutations in KCC2 are a known cause of infantile epilepsy in humans and KCC2 dysfunction is present in patients with both idiopathic and acquired epilepsy. Here we discuss the growing evidence that KCC2 dysfunction has a central role in the development and severity of the epilepsies.
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Affiliation(s)
- Yvonne E Moore
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK; Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Matt R Kelley
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Nicholas J Brandon
- AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, MA 02111, USA; AstraZeneca Neuroscience, Innovative Medicines and Early Development Biotech Unit, R&D Boston, Waltham, MA 024515, USA
| | - Tarek Z Deeb
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA; AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, MA 02111, USA
| | - Stephen J Moss
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK; Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA; AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, MA 02111, USA.
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Wright R, Newey SE, Ilie A, Wefelmeyer W, Raimondo JV, Ginham R, Mcllhinney RAJ, Akerman CJ. Neuronal Chloride Regulation via KCC2 Is Modulated through a GABA B Receptor Protein Complex. J Neurosci 2017; 37:5447-5462. [PMID: 28450542 PMCID: PMC5452337 DOI: 10.1523/jneurosci.2164-16.2017] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 03/31/2017] [Accepted: 04/06/2017] [Indexed: 01/06/2023] Open
Abstract
GABAB receptors are G-protein-coupled receptors that mediate inhibitory synaptic actions through a series of downstream target proteins. It is increasingly appreciated that the GABAB receptor forms part of larger signaling complexes, which enable the receptor to mediate multiple different effects within neurons. Here we report that GABAB receptors can physically associate with the potassium-chloride cotransporter protein, KCC2, which sets the driving force for the chloride-permeable ionotropic GABAA receptor in mature neurons. Using biochemical, molecular, and functional studies in rodent hippocampus, we show that activation of GABAB receptors results in a decrease in KCC2 function, which is associated with a reduction in the protein at the cell surface. These findings reveal a novel "crosstalk" between the GABA receptor systems, which can be recruited under conditions of high GABA release and which could be important for the regulation of inhibitory synaptic transmission.SIGNIFICANCE STATEMENT Synaptic inhibition in the brain is mediated by ionotropic GABAA receptors (GABAARs) and metabotropic GABAB receptors (GABABRs). To fully appreciate the function and regulation of these neurotransmitter receptors, we must understand their interactions with other proteins. We describe a novel association between the GABABR and the potassium-chloride cotransporter protein, KCC2. This association is significant because KCC2 sets the intracellular chloride concentration found in mature neurons and thereby establishes the driving force for the chloride-permeable GABAAR. We demonstrate that GABABR activation can regulate KCC2 at the cell surface in a manner that alters intracellular chloride and the reversal potential for the GABAAR. Our data therefore support an additional mechanism by which GABABRs are able to modulate fast synaptic inhibition.
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Affiliation(s)
| | | | | | | | | | - Rachel Ginham
- Medical Research Council Anatomical Neuropharmacology Unit, University of Oxford, Oxford, OX1 3QT, United Kingdom
| | - R A Jeffrey Mcllhinney
- Medical Research Council Anatomical Neuropharmacology Unit, University of Oxford, Oxford, OX1 3QT, United Kingdom
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Notartomaso S, Mascio G, Scarselli P, Martinello K, Fucile S, Gradini R, Bruno V, Battaglia G, Nicoletti F. Expression of the K +/Cl - cotransporter, KCC2, in cerebellar Purkinje cells is regulated by group-I metabotropic glutamate receptors. Neuropharmacology 2017; 115:51-59. [PMID: 27498071 DOI: 10.1016/j.neuropharm.2016.07.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 06/30/2016] [Accepted: 07/26/2016] [Indexed: 10/21/2022]
Abstract
The neuronal K+/Cl- symporter, KCC2, shapes synaptic responses mediated by Cl--permeant GABAA receptors. Moving from the evidence that excitatory neurotransmission drives changes in KCC2 expression in cerebellar neurons, we studied the regulation of KCC2 expression by group-I metabotropic glutamate (mGlu) receptors in the cerebellum of adult mice. Mice lacking mGlu5 receptors showed a large reduction in cerebellar KCC2 protein levels and a loss of KCC2 immunoreactivity in Purkinje cells. Similar changes were seen in mice treated with the mGlu5 receptor antagonist, MPEP, whereas treatment with the mGlu5 receptor positive allosteric modulator (PAM), VU0360172, increased KCC2 expression. In contrast, pharmacological inhibition of mGlu1 receptors with JNJ16259685 enhanced cerebellar KCC2 protein levels and KCC2 immunoreactivity in Purkinje cells, whereas treatment with the mGlu1 receptor PAM, RO0711401, reduced KCC2 expression. To examine whether the reduction in KCC2 expression caused by the absence or the inhibition of mGlu5 receptors could affect GABAergic transmission, we performed electrophysiological and behavioral studies. Recording of extracellular action potentials in Purkinje cells showed that the inhibitory effect of the GABAA receptor agonist, muscimol, was lost in cerebellar slices prepared from mGlu5-/- mice or from mice treated systemically with MPEP, in line with the reduction in KCC2 expression. Similarly, motor impairment caused by the GABAA receptor PAM, diazepam, was attenuated in mice pre-treated with MPEP. These findings disclose a novel function of mGlu5 receptors in the cerebellum and suggest that mGlu5 receptor ligands might influence GABAergic transmission in the cerebellum and affect motor responses to GABA-mimetic drugs. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'.
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Affiliation(s)
| | | | | | | | - Sergio Fucile
- IRCCS Neuromed, Pozzilli, Italy; Department of Physiology and Pharmacology, University Sapienza of Rome, Italy
| | - Roberto Gradini
- IRCCS Neuromed, Pozzilli, Italy; Department of Experimental Medicine, University Sapienza of Rome, Italy
| | - Valeria Bruno
- IRCCS Neuromed, Pozzilli, Italy; Department of Physiology and Pharmacology, University Sapienza of Rome, Italy
| | | | - Ferdinando Nicoletti
- IRCCS Neuromed, Pozzilli, Italy; Department of Physiology and Pharmacology, University Sapienza of Rome, Italy.
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