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Boutonnet M, Carpena C, Bouquier N, Chastagnier Y, Font-Ingles J, Moutin E, Tricoire L, Chemin J, Perroy J. Voltage tunes mGlu 5 receptor function, impacting synaptic transmission. Br J Pharmacol 2024; 181:1793-1811. [PMID: 38369690 DOI: 10.1111/bph.16317] [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: 09/07/2023] [Revised: 12/08/2023] [Accepted: 12/29/2023] [Indexed: 02/20/2024] Open
Abstract
BACKGROUND AND PURPOSE Voltage sensitivity is a common feature of many membrane proteins, including some G-protein coupled receptors (GPCRs). However, the functional consequences of voltage sensitivity in GPCRs are not well understood. EXPERIMENTAL APPROACH In this study, we investigated the voltage sensitivity of the post-synaptic metabotropic glutamate receptor mGlu5 and its impact on synaptic transmission. Using biosensors and electrophysiological recordings in non-excitable HEK293T cells or neurons. KEY RESULTS We found that mGlu5 receptor function is optimal at resting membrane potentials. We observed that membrane depolarization significantly reduced mGlu5 receptor activation, Gq-PLC/PKC stimulation, Ca2+ release and mGlu5 receptor-gated currents through transient receptor potential canonical, TRPC6, channels or glutamate ionotropic NMDA receptors. Notably, we report a previously unknown activity of the NMDA receptor at the resting potential of neurons, enabled by mGlu5. CONCLUSIONS AND IMPLICATIONS Our findings suggest that mGlu5 receptor activity is directly regulated by membrane voltage which may have a significant impact on synaptic processes and pathophysiological functions.
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Affiliation(s)
- Marin Boutonnet
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Camille Carpena
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | | | - Yan Chastagnier
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Joan Font-Ingles
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
- SpliceBio, Barcelona, Spain
| | - Enora Moutin
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Ludovic Tricoire
- Neuroscience Paris Seine, Institut de biologie Paris Seine, Sorbonne universite, CNRS, INSERM, Paris, France
| | - Jean Chemin
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Julie Perroy
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
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2
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Peslalz P, Kraus F, Izzo F, Bleisch A, El Hamdaoui Y, Schulz I, Kany AM, Hirsch AKH, Friedland K, Plietker B. Selective Activation of a TRPC6 Ion Channel Over TRPC3 by Metalated Type-B Polycyclic Polyprenylated Acylphloroglucinols. J Med Chem 2023; 66:15061-15072. [PMID: 37922400 DOI: 10.1021/acs.jmedchem.3c01170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2023]
Abstract
Selective modulation of TRPC6 ion channels is a promising therapeutic approach for neurodegenerative diseases and depression. A significant advancement showcases the selective activation of TRPC6 through metalated type-B PPAP, termed PPAP53. This success stems from PPAP53's 1,3-diketone motif facilitating metal coordination. PPAP53 is water-soluble and as potent as hyperforin, the gold standard in this field. In contrast to type-A, type-B PPAPs offer advantages such as gram-scale synthesis, easy derivatization, and long-term stability. Our investigations reveal PPAP53 selectively binding to the C-terminus of TRPC6. Although cryoelectron microscopy has resolved the majority of the TRPC6 structure, the binding site in the C-terminus remained unresolved. To address this issue, we employed state-of-the-art artificial-intelligence-based protein structure prediction algorithms to predict the missing region. Our computational results, validated against experimental data, indicate that PPAP53 binds to the 777LLKL780-region of the C-terminus, thus providing critical insights into the binding mechanism of PPAP53.
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Affiliation(s)
- Philipp Peslalz
- Chair of Organic Chemistry, Faculty of Chemistry and Food Chemistry, Technical University Dresden, Bergstr. 66, Dresden 01069, Germany
| | - Frank Kraus
- Institut für Organische Chemie, Universität Stuttgart , Pfaffenwaldring 55, Stuttgart 70569, Germany
| | - Flavia Izzo
- Institut für Organische Chemie, Universität Stuttgart , Pfaffenwaldring 55, Stuttgart 70569, Germany
| | - Anton Bleisch
- Chair of Organic Chemistry, Faculty of Chemistry and Food Chemistry, Technical University Dresden, Bergstr. 66, Dresden 01069, Germany
| | - Yamina El Hamdaoui
- Institut für Biomedizinische und Pharmazeutische Wissenschaften Johannes Gutenberg-Universität Mainz, Mainz 55128, Germany
| | - Ina Schulz
- Institut für Biomedizinische und Pharmazeutische Wissenschaften Johannes Gutenberg-Universität Mainz, Mainz 55128, Germany
| | - Andreas M Kany
- Helmholtz Institute for Pharm. Research Saarland (HIPS)-Helmholtz Centre for Infection Research (HZI), Saarbrücken 66123, Germany
| | - Anna K H Hirsch
- Helmholtz Institute for Pharm. Research Saarland (HIPS)-Helmholtz Centre for Infection Research (HZI), Saarbrücken 66123, Germany
- Department of Pharmacy, Saarland University, Saarbrücken 66123, Germany
| | - Kristina Friedland
- Institut für Biomedizinische und Pharmazeutische Wissenschaften Johannes Gutenberg-Universität Mainz, Mainz 55128, Germany
| | - Bernd Plietker
- Chair of Organic Chemistry, Faculty of Chemistry and Food Chemistry, Technical University Dresden, Bergstr. 66, Dresden 01069, Germany
- Institut für Organische Chemie, Universität Stuttgart , Pfaffenwaldring 55, Stuttgart 70569, Germany
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3
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Zernov N, Popugaeva E. Role of Neuronal TRPC6 Channels in Synapse Development, Memory Formation and Animal Behavior. Int J Mol Sci 2023; 24:15415. [PMID: 37895105 PMCID: PMC10607207 DOI: 10.3390/ijms242015415] [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: 09/08/2023] [Revised: 10/11/2023] [Accepted: 10/16/2023] [Indexed: 10/29/2023] Open
Abstract
The transient receptor potential cation channel, subfamily C, member 6 (TRPC6), has been believed to adjust the formation of an excitatory synapse. The positive regulation of TRPC6 engenders synapse enlargement and improved learning and memory in animal models. TRPC6 is involved in different synaptoprotective signaling pathways, including antagonism of N-methyl-D-aspartate receptor (NMDAR), activation of brain-derived neurotrophic factor (BDNF) and postsynaptic store-operated calcium entry. Positive regulation of TRPC6 channels has been repeatedly shown to be good for memory formation and storage. TRPC6 is mainly expressed in the hippocampus, particularly in the dentate granule cells, cornu Ammonis 3 (CA3) pyramidal cells and gamma-aminobutyric acid (GABA)ergic interneurons. It has been observed that TRPC6 agonists have a great influence on animal behavior including memory formation and storage The purpose of this review is to collect the available information on the role of TRPC6 in memory formation in various parts of the brain to understand how TRPC6-specific pharmaceutical agents will affect memory in distinct parts of the central nervous system (CNS).
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Affiliation(s)
| | - Elena Popugaeva
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia
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4
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New Positive TRPC6 Modulator Penetrates Blood–Brain Barrier, Eliminates Synaptic Deficiency and Restores Memory Deficit in 5xFAD Mice. Int J Mol Sci 2022; 23:ijms232113552. [PMID: 36362339 PMCID: PMC9653995 DOI: 10.3390/ijms232113552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 11/01/2022] [Accepted: 11/01/2022] [Indexed: 11/09/2022] Open
Abstract
Synapse loss in the brain of Alzheimer’s disease patients correlates with cognitive dysfunctions. Drugs that limit synaptic loss are promising pharmacological agents. The transient receptor potential cation channel, subfamily C, member 6 (TRPC6) regulates the formation of an excitatory synapse. Positive regulation of TRPC6 results in increased synapse formation and enhances learning and memory in animal models. The novel selective TRPC6 agonist, 3-(3-,4-Dihydro-6,7-dimethoxy-3,3-dimethyl-1-isoquinolinyl)-2H-1-benzopyran-2-one, has recently been identified. Here we present in silico, in vitro, ex vivo, pharmacokinetic and in vivo studies of this compound. We demonstrate that it binds to the extracellular agonist binding site of the human TRPC6, protects hippocampal mushroom spines from amyloid toxicity in vitro, efficiently recovers synaptic plasticity in 5xFAD brain slices, penetrates the blood–brain barrier and recovers cognitive deficits in 5xFAD mice. We suggest that C20 might be recognized as the novel TRPC6-selective drug suitable to treat synaptic deficiency in Alzheimer’s disease-affected hippocampal neurons.
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El Hamdaoui Y, Zheng F, Fritz N, Ye L, Tran MA, Schwickert K, Schirmeister T, Braeuning A, Lichtenstein D, Hellmich UA, Weikert D, Heinrich M, Treccani G, Schäfer MKE, Nowak G, Nürnberg B, Alzheimer C, Müller CP, Friedland K. Analysis of hyperforin (St. John's wort) action at TRPC6 channel leads to the development of a new class of antidepressant drugs. Mol Psychiatry 2022; 27:5070-5085. [PMID: 36224261 PMCID: PMC9763113 DOI: 10.1038/s41380-022-01804-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 09/02/2022] [Accepted: 09/14/2022] [Indexed: 01/14/2023]
Abstract
St. John's wort is an herb, long used in folk medicine for the treatment of mild depression. Its antidepressant constituent, hyperforin, has properties such as chemical instability and induction of drug-drug interactions that preclude its use for individual pharmacotherapies. Here we identify the transient receptor potential canonical 6 channel (TRPC6) as a druggable target to control anxious and depressive behavior and as a requirement for hyperforin antidepressant action. We demonstrate that TRPC6 deficiency in mice not only results in anxious and depressive behavior, but also reduces excitability of hippocampal CA1 pyramidal neurons and dentate gyrus granule cells. Using electrophysiology and targeted mutagenesis, we show that hyperforin activates the channel via a specific binding motif at TRPC6. We performed an analysis of hyperforin action to develop a new antidepressant drug that uses the same TRPC6 target mechanism for its antidepressant action. We synthesized the hyperforin analog Hyp13, which shows similar binding to TRPC6 and recapitulates TRPC6-dependent anxiolytic and antidepressant effects in mice. Hyp13 does not activate pregnan-X-receptor (PXR) and thereby loses the potential to induce drug-drug interactions. This may provide a new approach to develop better treatments for depression, since depression remains one of the most treatment-resistant mental disorders, warranting the development of effective drugs based on naturally occurring compounds.
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Affiliation(s)
- Yamina El Hamdaoui
- grid.5802.f0000 0001 1941 7111Pharmacology & Toxicology, Institute for Pharmaceutical and Biomedical Sciences, Johannes-Gutenberg Universität Mainz (JGU), Mainz, Germany
| | - Fang Zheng
- grid.5330.50000 0001 2107 3311Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Nikolas Fritz
- grid.5802.f0000 0001 1941 7111Pharmacology & Toxicology, Institute for Pharmaceutical and Biomedical Sciences, Johannes-Gutenberg Universität Mainz (JGU), Mainz, Germany
| | - Lian Ye
- grid.5802.f0000 0001 1941 7111Pharmacology & Toxicology, Institute for Pharmaceutical and Biomedical Sciences, Johannes-Gutenberg Universität Mainz (JGU), Mainz, Germany
| | - Mai Anh Tran
- grid.9613.d0000 0001 1939 2794Institute of Organic Chemistry and Macromolecular Chemistry, Faculty of Chemistry and Earth Science, Friedrich Schiller University Jena, Jena, Germany ,grid.5802.f0000 0001 1941 7111Biochemistry, Department of Chemistry, Johannes-Gutenberg Universität Mainz, Mainz, Germany
| | - Kevin Schwickert
- grid.5802.f0000 0001 1941 7111Pharmacology & Toxicology, Institute for Pharmaceutical and Biomedical Sciences, Johannes-Gutenberg Universität Mainz (JGU), Mainz, Germany
| | - Tanja Schirmeister
- grid.5802.f0000 0001 1941 7111Pharmacology & Toxicology, Institute for Pharmaceutical and Biomedical Sciences, Johannes-Gutenberg Universität Mainz (JGU), Mainz, Germany
| | - Albert Braeuning
- grid.417830.90000 0000 8852 3623Department of Food Safety, German Federal Institute for Risk Assessment, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany
| | - Dajana Lichtenstein
- grid.417830.90000 0000 8852 3623Department of Food Safety, German Federal Institute for Risk Assessment, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany
| | - Ute A. Hellmich
- grid.9613.d0000 0001 1939 2794Institute of Organic Chemistry and Macromolecular Chemistry, Faculty of Chemistry and Earth Science, Friedrich Schiller University Jena, Jena, Germany ,grid.5802.f0000 0001 1941 7111Biochemistry, Department of Chemistry, Johannes-Gutenberg Universität Mainz, Mainz, Germany ,grid.517250.4Cluster of Excellence “Balance of the Microverse”, Friedrich-Schiller-Uniersität Jena, Jena, Germany ,grid.7839.50000 0004 1936 9721Center for Biomolecular Magnetic Resonance, Goethe-University, Frankfurt, Germany
| | - Dorothee Weikert
- grid.5330.50000 0001 2107 3311Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Markus Heinrich
- grid.5330.50000 0001 2107 3311Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Giulia Treccani
- grid.410607.4Department of Psychiatry and Psychotherapy, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany ,grid.410607.4Institute of Anatomy, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Michael K. E. Schäfer
- grid.410607.4Department of Anesthesiology, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstr. 1 (Bld. 505), 55131 Mainz, Germany
| | - Gabriel Nowak
- grid.5522.00000 0001 2162 9631Department of Pharmacobiology, Jagiellonian University Medical College, Krakow, Poland
| | - Bernd Nürnberg
- grid.10392.390000 0001 2190 1447Department of Pharmacology, Experimental Therapy & Toxicology, Eberhard-Karls-University of Tübingen, Tübingen, Germany
| | - Christian Alzheimer
- grid.5330.50000 0001 2107 3311Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Christian P. Müller
- grid.5330.50000 0001 2107 3311Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany ,grid.11875.3a0000 0001 2294 3534Centre for Drug Research, Universiti Sains Malaysia, 11800 Minden, Penang Malaysia
| | - Kristina Friedland
- Pharmacology & Toxicology, Institute for Pharmaceutical and Biomedical Sciences, Johannes-Gutenberg Universität Mainz (JGU), Mainz, Germany.
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6
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Xie R, Wang Z, Liu T, Xiao R, Lv K, Wu C, Luo Y, Cai Y, Fan X. AAV Delivery of shRNA Against TRPC6 in Mouse Hippocampus Impairs Cognitive Function. Front Cell Dev Biol 2021; 9:688655. [PMID: 34327201 PMCID: PMC8313999 DOI: 10.3389/fcell.2021.688655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 06/22/2021] [Indexed: 11/13/2022] Open
Abstract
Transient Receptor Potential Canonical 6 (TRPC6) has been suggested to be involved in synapse function and contribute to hippocampal-dependent cognitive processes. Gene silencing of TRPC6 was performed by injecting adeno-associated virus (AAV) expressing TRPC6-specific shRNA (shRNA-TRPC6) into the hippocampal dentate gyrus (DG). Spatial learning, working memory and social recognition memory were impaired in the shRNA-TRPC6 treated mice compared to control mice after 4 weeks. In addition, gene ontology (GO) analysis of RNA-sequencing revealed that viral intervention of TRPC6 expression in DG resulted in the enrichment of the process of synaptic transmission and cellular compartment of synaptic structure. KEGG analysis showed PI3K-Akt signaling pathway were significantly down-regulated. Furthermore, the shRNA-TRPC6 treatment reduced dendritic spines of DG granule neurons, in terms of spine loss, the thin and mushroom types predominated. Accompanying the spine loss, the levels of PSD95, pAkt and CREB in the hippocampus were decreased in the shRNA-TRPC6 treated animals. Taken together, our results suggest that knocking down TRPC6 in the DG have a disadvantageous effect on cognitive processes.
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Affiliation(s)
- Ruxin Xie
- Department of Military Cognitive Psychology, School of Psychology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Zhongke Wang
- Department of Military Cognitive Psychology, School of Psychology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Tianyao Liu
- Department of Military Cognitive Psychology, School of Psychology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Rui Xiao
- Department of Military Cognitive Psychology, School of Psychology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Keyi Lv
- Department of Military Cognitive Psychology, School of Psychology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Chuan Wu
- Department of Military Cognitive Psychology, School of Psychology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Yi Luo
- Department of Military Cognitive Psychology, School of Psychology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Yun Cai
- Department of Military Cognitive Psychology, School of Psychology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Xiaotang Fan
- Department of Military Cognitive Psychology, School of Psychology, Third Military Medical University (Army Medical University), Chongqing, China
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7
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Therapeutic potential of pharmacological agents targeting TRP channels in CNS disorders. Pharmacol Res 2020; 159:105026. [PMID: 32562815 DOI: 10.1016/j.phrs.2020.105026] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 05/21/2020] [Accepted: 06/11/2020] [Indexed: 02/07/2023]
Abstract
Central nervous system (CNS) disorders like Alzheimer's disease (AD), Parkinson disease (PD), stroke, epilepsy, depression, and bipolar disorder have a high impact on both medical and social problems due to the surge in their prevalence. All of these neuronal disorders share some common etiologies including disruption of Ca2+ homeostasis and accumulation of misfolded proteins. These misfolded proteins further disrupt the intracellular Ca2+ homeostasis by disrupting the activity of several ion channels including transient receptor potential (TRP) channels. TRP channel families include non-selective Ca2+ permeable channels, which act as cellular sensors activated by various physio-chemical stimuli, exogenous, and endogenous ligands responsible for maintaining the intracellular Ca2+ homeostasis. TRP channels are abundantly expressed in the neuronal cells and disturbance in their activity leads to various neuronal diseases. Under the pathological conditions when the activity of TRP channels is perturbed, there is a disruption of the neuronal homeostasis through increased inflammatory response, generation of reactive oxygen species, and mitochondrial dysfunction. Therefore, there is a potential of pharmacological interventions targeting TRP channels in CNS disorders. This review focuses on the role of TRP channels in neurological diseases; also, we have highlighted the current insights into the pharmacological modulators targeting TRP channels.
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8
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How TRPC Channels Modulate Hippocampal Function. Int J Mol Sci 2020; 21:ijms21113915. [PMID: 32486187 PMCID: PMC7312571 DOI: 10.3390/ijms21113915] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 05/27/2020] [Accepted: 05/28/2020] [Indexed: 12/12/2022] Open
Abstract
Transient receptor potential canonical (TRPC) proteins constitute a group of receptor-operated calcium-permeable nonselective cationic membrane channels of the TRP superfamily. They are largely expressed in the hippocampus and are able to modulate neuronal functions. Accordingly, they have been involved in different hippocampal functions such as learning processes and different types of memories, as well as hippocampal dysfunctions such as seizures. This review covers the mechanisms of activation of these channels, how these channels can modulate neuronal excitability, in particular the after-burst hyperpolarization, and in the persistent activity, how they control synaptic plasticity including pre- and postsynaptic processes and how they can interfere with cell survival and neurogenesis.
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TRPC6-Mediated ERK1/2 Activation Increases Dentate Granule Cell Resistance to Status Epilepticus Via Regulating Lon Protease-1 Expression and Mitochondrial Dynamics. Cells 2019; 8:cells8111376. [PMID: 31683954 PMCID: PMC6912337 DOI: 10.3390/cells8111376] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Revised: 10/21/2019] [Accepted: 10/30/2019] [Indexed: 12/28/2022] Open
Abstract
Transient receptor potential canonical channel-6 (TRPC6) is one of the Ca2+-permeable non-selective cation channels. TRPC6 is mainly expressed in dentate granule cell (DGC), which is one of the most resistant neuronal populations to various harmful stresses. Although TRPC6 knockdown evokes the massive DGC degeneration induced by status epilepticus (a prolonged seizure activity, SE), the molecular mechanisms underlying the role of TRPC6 in DGC viability in response to SE are still unclear. In the present study, hyperforin (a TRPC6 activator) facilitated mitochondrial fission in DGC concomitant with increases in Lon protease-1 (LONP1, a mitochondrial protease) expression and extracellular-signal-regulated kinase 1/2 (ERK1/2) phosphorylation under physiological conditions, which were abrogated by U0126 (an ERK1/2 inhibitor) co-treatment. TRPC6 knockdown showed the opposite effects on LONP1 expression, ERK1/2 activity, and mitochondrial dynamics. In addition, TRPC6 siRNA and U0126 evoked the massive DGC degeneration accompanied by mitochondrial elongation following SE, independent of seizure severity. However, LONP1 siRNA exacerbated SE-induced DGC death without affecting mitochondrial length. These findings indicate that TRPC6-ERK1/2 activation may increase DGC invulnerability to SE by regulating LONP1 expression as well as mitochondrial dynamics. Therefore, TRPC6-ERK1/2-LONP1 signaling pathway will be an interesting and important therapeutic target for neuroprotection from various neurological diseases.
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Martinello K, Giacalone E, Migliore M, Brown DA, Shah MM. The subthreshold-active K V7 current regulates neurotransmission by limiting spike-induced Ca 2+ influx in hippocampal mossy fiber synaptic terminals. Commun Biol 2019; 2:145. [PMID: 31044170 PMCID: PMC6486593 DOI: 10.1038/s42003-019-0408-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/29/2019] [Indexed: 12/23/2022] Open
Abstract
Little is known about the properties and function of ion channels that affect synaptic terminal-resting properties. One particular subthreshold-active ion channel, the Kv7 potassium channel, is highly localized to axons, but its role in regulating synaptic terminal intrinsic excitability and release is largely unexplored. Using electrophysiological recordings together with computational modeling, we found that the KV7 current was active at rest in adult hippocampal mossy fiber synaptic terminals and enhanced their membrane conductance. The current also restrained action potential-induced Ca2+ influx via N- and P/Q-type Ca2+ channels in boutons. This was associated with a substantial reduction in the spike half-width and afterdepolarization following presynaptic spikes. Further, by constraining spike-induced Ca2+ influx, the presynaptic KV7 current decreased neurotransmission onto CA3 pyramidal neurons and short-term synaptic plasticity at the mossy fiber-CA3 synapse. This is a distinctive mechanism by which KV7 channels influence hippocampal neuronal excitability and synaptic plasticity.
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Affiliation(s)
| | | | - Michele Migliore
- Institute of Biophysics, National Research Council, 90146 Palermo, Italy
| | - David A. Brown
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT UK
| | - Mala M. Shah
- UCL School of Pharmacy University College London, London, WC1N 1AX UK
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11
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Discovery and characterization of a positive allosteric modulator of transient receptor potential canonical 6 (TRPC6) channels. Cell Calcium 2018; 78:26-34. [PMID: 30594060 DOI: 10.1016/j.ceca.2018.12.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 12/20/2018] [Accepted: 12/20/2018] [Indexed: 01/13/2023]
Abstract
The non-selective second messenger-gated cation channel TRPC6 (transient receptor potential canonical 6) is activated by diacylglycerols (DAG) in a PKC-independent manner and plays important roles in a variety of physiological processes and diseases. In order to facilitate novel therapies, the development of potent inhibitors as well as channel-activating agents is of great interest. The screening of a chemical library, comprising about 17,000 small molecule compounds, revealed an agent, which induced increases in intracellular Ca2+ concentrations ([Ca2+]i) in a concentration-dependent manner (EC50 = 2.37 ± 0.25 μM) in stably TRPC6-expressing HEK293 cells. This new compound (C20) selectively acts on TRPC6, unlike OAG (1-oleoyl-1-acetyl-sn-glycerol), which also activates PKC and does not discriminate between TRPC6 and the closely related channels TRPC3 and TRPC7. Further evaluation by Ca2+ assays and electrophysiological studies revealed that C20 rather operated as an enhancer of channel activation than as an activator by itself and led to the assumption that the compound C20 is an allosteric modulator of TRPC6, enabling low basal concentrations of DAG to induce activation of the ion channel. Furthermore, C20 was tested in human platelets that express TRPC6. A combined activation of TRPC6 with C20 and OAG elicited a robust increase in [Ca2+]i in human platelets. This potentiated channel activation was sensitive to TRPC6 channel blockers. To achieve sufficient amounts of C20 for biological studies, we applied a one-pot synthesis strategy. With regard to studies in native systems, the sensitizing ability of C20 can be a valuable pharmacological tool to selectively exaggerate TRPC6-dependent signals.
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12
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Govindaiah G, Kang YJ, Lewis HES, Chung L, Clement EM, Greenfield LJ, Garcia-Rill E, Lee SH. Group I metabotropic glutamate receptors generate two types of intrinsic membrane oscillations in hippocampal oriens/alveus interneurons. Neuropharmacology 2018; 139:150-162. [PMID: 29964095 DOI: 10.1016/j.neuropharm.2018.06.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/16/2018] [Accepted: 06/27/2018] [Indexed: 12/21/2022]
Abstract
GABAergic interneurons in the hippocampus are critically involved in almost all hippocampal circuit functions including coordinated network activity. Somatostatin-expressing oriens-lacunosum moleculare (O-LM) interneurons are a major subtype of dendritically projecting interneurons in hippocampal subregions (e.g., CA1), and express group I metabotropic glutamate receptors (mGluRs), specifically mGluR1 and mGluR5. Group I mGluRs are thought to regulate hippocampal circuit functions partially through GABAergic interneurons. Previous studies suggest that a group I/II mGluR agonist produces slow supra-threshold membrane oscillations (<0.1 Hz), which are associated with high-frequency action potential (AP) discharges in O-LM interneurons. However, the properties and underlying mechanisms of these slow oscillations remain largely unknown. We performed whole-cell patch-clamp recordings from mouse interneurons in the stratum oriens/alveus (O/A interneurons) including CA1 O-LM interneurons. Our study revealed that the selective mGluR1/5 agonist (S)-3,5-dihydroxyphenylglycine (DHPG) induced slow membrane oscillations (<0.1 Hz), which were associated with gamma frequency APs followed by AP-free perithreshold gamma oscillations. The selective mGluR1 antagonist (S)-(+)-α-Amino-4-carboxy-2-methylbenzeneacetic acid (LY367385) reduced the slow oscillations, and the selective mGluR5 antagonist 2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP) partially blocked them. Blockade of nonselective cation-conducting transient receptor potential channels, L-type Ca2+ channels, or ryanodine receptors all abolished the slow oscillations, suggesting the involvement of multiple mechanisms. Our findings suggest that group I mGluR activation in O/A interneurons may play an important role in coordinated network activity, and O/A interneuron vulnerability to excitotoxicity, in disease states like seizures, is at least in part due to an excessive rise in intracellular Ca2+.
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Affiliation(s)
- Gubbi Govindaiah
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Young-Jin Kang
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | | | - Leeyup Chung
- Department of Neurobiology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Ethan M Clement
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Lazar John Greenfield
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; Department of Neurology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Edgar Garcia-Rill
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Sang-Hun Lee
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
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Reboreda A, Theissen FM, Valero-Aracama MJ, Arboit A, Corbu MA, Yoshida M. Do TRPC channels support working memory? Comparing modulations of TRPC channels and working memory through G-protein coupled receptors and neuromodulators. Behav Brain Res 2018; 354:64-83. [PMID: 29501506 DOI: 10.1016/j.bbr.2018.02.042] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 02/27/2018] [Accepted: 02/27/2018] [Indexed: 12/11/2022]
Abstract
Working memory is a crucial ability we use in daily life. However, the cellular mechanisms supporting working memory still remain largely unclear. A key component of working memory is persistent neural firing which is believed to serve short-term (hundreds of milliseconds up to tens of seconds) maintenance of necessary information. In this review, we will focus on the role of transient receptor potential canonical (TRPC) channels as a mechanism underlying persistent firing. Many years of in vitro work have been suggesting a crucial role of TRPC channels in working memory and temporal association tasks. If TRPC channels are indeed a central mechanism for working memory, manipulations which impair or facilitate working memory should have a similar effect on TRPC channel modulation. However, modulations of working memory and TRPC channels were never systematically compared, and it remains unanswered whether TRPC channels indeed contribute to working memory in vivo or not. In this article, we review the effects of G-protein coupled receptors (GPCR) and neuromodulators, including acetylcholine, noradrenalin, serotonin and dopamine, on working memory and TRPC channels. Based on comparisons, we argue that GPCR and downstream signaling pathways that activate TRPC, generally support working memory, while those that suppress TRPC channels impair it. However, depending on the channel types, areas, and systems tested, this is not the case in all studies. Further work to clarify involvement of specific TRPC channels in working memory tasks and how they are affected by neuromodulators is still necessary in the future.
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Affiliation(s)
- Antonio Reboreda
- Leibniz Institute for Neurobiology (LIN) Magdeburg, Brenneckestraße 6, 39118 Magdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE) Magdeburg, Leipziger Str. 44/Haus 64, 39120, Magdeburg, Germany.
| | - Frederik M Theissen
- German Center for Neurodegenerative Diseases (DZNE) Magdeburg, Leipziger Str. 44/Haus 64, 39120, Magdeburg, Germany
| | - Maria J Valero-Aracama
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsstraße 17, 91054 Erlangen, Germany
| | - Alberto Arboit
- German Center for Neurodegenerative Diseases (DZNE) Magdeburg, Leipziger Str. 44/Haus 64, 39120, Magdeburg, Germany
| | - Mihaela A Corbu
- Ruhr University Bochum (RUB), Universitätsstraße 150, 44801, Bochum, Germany
| | - Motoharu Yoshida
- Leibniz Institute for Neurobiology (LIN) Magdeburg, Brenneckestraße 6, 39118 Magdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE) Magdeburg, Leipziger Str. 44/Haus 64, 39120, Magdeburg, Germany; Center for Behavioral Brain Sciences, 39106, Magdeburg, Germany.
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Kim JE, Park JY, Kang TC. TRPC6-mediated ERK1/2 Activation Regulates Neuronal Excitability via Subcellular Kv4.3 Localization in the Rat Hippocampus. Front Cell Neurosci 2017; 11:413. [PMID: 29326557 PMCID: PMC5742353 DOI: 10.3389/fncel.2017.00413] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 12/11/2017] [Indexed: 01/02/2023] Open
Abstract
Recently, we have reported that transient receptor potential channel-6 (TRPC6) plays an important role in the regulation of neuronal excitability and synchronization of spiking activity in the dentate granule cells (DGC). However, the underlying mechanisms of TRPC6 in these phenomena have been still unclear. In the present study, we investigated the role of TRPC6 in subcellular localization of Kv4.3 and its relevance to neuronal excitability in the rat hippocampus. TRPC6 knockdown increased excitability and inhibitory transmission in the DGC and the CA1 neurons in response to a paired-pulse stimulus. However, TRPC6 knockdown impaired γ-aminobutyric acid (GABA)ergic inhibition in the hippocampus during and after high-frequency stimulation (HFS). TRPC6 knockdown reduced the Kv4.3 clusters in membrane fractions and its dendritic localization on DGC and GABAergic interneurons. TRPC6 knockdown also decreased extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation and the efficacy of 4-aminopyridine (4-AP) in neuronal excitability. An ERK1/2 inhibitor generated multiple population spikes in response to a paired-pulse stimulus, concomitant with reduced membrane Kv4.3 translocation. A TRPC6 activator (hyperforin) reversed the effects of TRPC knockdown, except paired-pulse inhibition. These findings provide valuable clues indicating that TRPC6-mediated ERK1/2 activation may regulate subcellular Kv4.3 localization in DGC and interneurons, which is cause-effect relationship between neuronal excitability and seizure susceptibility.
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Affiliation(s)
- Ji-Eun Kim
- Department of Anatomy and Neurobiology, Institute of Epilepsy Research, College of Medicine, Hallym University, Chuncheon, South Korea
| | - Jin-Young Park
- Department of Anatomy and Neurobiology, Institute of Epilepsy Research, College of Medicine, Hallym University, Chuncheon, South Korea
| | - Tae-Cheon Kang
- Department of Anatomy and Neurobiology, Institute of Epilepsy Research, College of Medicine, Hallym University, Chuncheon, South Korea
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TRPC6-mediated ERK1/2 phosphorylation prevents dentate granule cell degeneration via inhibiting mitochondrial elongation. Neuropharmacology 2017; 121:120-129. [PMID: 28479396 DOI: 10.1016/j.neuropharm.2017.05.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 04/14/2017] [Accepted: 05/03/2017] [Indexed: 12/16/2022]
Abstract
Transient receptor potential canonical channel-6 (TRPC6) is one of Ca2+-permeable non-selective cation channels. In the rat hippocampus, TRPC6 expression is predominantly observed in dentate granule cells (DGC) rather than other hippocampal components. Interestingly, TRPC6 knockdown results in the massive DGC degeneration following status epilepticus (SE), although DGC is one of the resistant neuronal populations to various harmful stresses. However, the molecular events underlying the DGC degeneration induced by TRPC6 knockdown are still unclear. In the present study, TRPC6 knockdown resulted in mitochondrial elongation accompanied by reduction in dynamin-related proteins 1 (DRP1)-S616 phosphorylation. Furthermore, TRPC6 knockdown selectively decreased extracellular-signal-regulated kinase 1/2 (ERK1/2) phosphorylation. Similar to TRPC6 knockdown, ERK1/2 inhibition by U0126 evoked mitochondrial elongation with diminished DRP1-S616 phosphorylation, and facilitated SE-induced DGC degeneration independent of seizure severity. These findings indicate that TRPC6 may regulate mitochondrial dynamics via ERK1/2-mediaed DRP1 activation, which would be involved in DGC invulnerability to SE. Therefore, TRPC6 will be an interesting and important therapeutic target for neurological diseases related to impaired mitochondrial dynamics.
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16
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Single-cell RNAseq reveals cell adhesion molecule profiles in electrophysiologically defined neurons. Proc Natl Acad Sci U S A 2016; 113:E5222-31. [PMID: 27531958 DOI: 10.1073/pnas.1610155113] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In brain, signaling mediated by cell adhesion molecules defines the identity and functional properties of synapses. The specificity of presynaptic and postsynaptic interactions that is presumably mediated by cell adhesion molecules suggests that there exists a logic that could explain neuronal connectivity at the molecular level. Despite its importance, however, the nature of such logic is poorly understood, and even basic parameters, such as the number, identity, and single-cell expression profiles of candidate synaptic cell adhesion molecules, are not known. Here, we devised a comprehensive list of genes involved in cell adhesion, and used single-cell RNA sequencing (RNAseq) to analyze their expression in electrophysiologically defined interneurons and projection neurons. We compared the cell type-specific expression of these genes with that of genes involved in transmembrane ion conductances (i.e., channels), exocytosis, and rho/rac signaling, which regulates the actin cytoskeleton. Using these data, we identified two independent, developmentally regulated networks of interacting genes encoding molecules involved in cell adhesion, exocytosis, and signal transduction. Our approach provides a framework for a presumed cell adhesion and signaling code in neurons, enables correlating electrophysiological with molecular properties of neurons, and suggests avenues toward understanding synaptic specificity.
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Urban N, Wang L, Kwiek S, Rademann J, Kuebler WM, Schaefer M. Identification and Validation of Larixyl Acetate as a Potent TRPC6 Inhibitor. Mol Pharmacol 2015; 89:197-213. [PMID: 26500253 DOI: 10.1124/mol.115.100792] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 10/21/2015] [Indexed: 01/17/2023] Open
Abstract
Classical or canonical transient receptor potential 6 (TRPC6), a nonselective and Ca(2+)-permeable cation channel, mediates pathophysiological responses within pulmonary and renal diseases that are still poorly controlled by current medication. Thus, controlling TRPC6 activity may provide a promising and challenging pharmacological approach. Recently identified chemical entities have demonstrated that TRPC6 is pharmacologically targetable. However, isotype-selectivity with regard to its closest relative, TRPC3, is difficult to achieve. Reasoning that balsams, essential oils, or incense materials that are traditionally used for inhalation may contain biologic activities to block TRPC6 activity, we embarked on a natural compound strategy to identify new TRPC6-blocking chemical entities. Within several preparations of plant extracts, a strong TRPC6-inhibitory activity was found in conifer balsams. The biologic activity was associated with nonvolatile resins, but not with essential oils. Of various conifers, the larch balsam was unique in displaying a marked TRPC6-prevalent mode of action. By testing the main constituents of larch resin, we identified larixol and larixyl acetate as blockers of Ca(2+) entry and ionic currents through diacylglycerol- or receptor-activated recombinant TRPC6 channels, exhibiting approximately 12- and 5-fold selectivity compared with its closest relatives TRPC3 and TRPC7, respectively. No significant inhibition of more distantly related TRPV or TRPM channels was seen. The potent inhibition of recombinant TRPC6 by larixyl acetate (IC50 = 0.1-0.6 µM) was confirmed for native TRPC6-like [Ca(2+)]i signals in diacylglycerol-stimulated rat pulmonary artery smooth muscle cells. In isolated mouse lungs, larix-6-yl monoacetate (CAS 4608-49-5; larixyl acetate; 5 µM) prevented acute hypoxia-induced vasoconstriction. We conclude that larch-derived labdane-type diterpenes are TRPC6-selective inhibitors and may represent a starting point for pharmacological TRPC6 modulation within experimental therapies.
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Affiliation(s)
- Nicole Urban
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, Germany (N.U., M.S.); Institut für Pharmazie, Freie Universität Berlin, Berlin, Germany (S.K., J.R.); and The Keenan Research Centre of St. Michael's Hospital, Toronto, Canada (L.W., W.M.K.)
| | - Liming Wang
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, Germany (N.U., M.S.); Institut für Pharmazie, Freie Universität Berlin, Berlin, Germany (S.K., J.R.); and The Keenan Research Centre of St. Michael's Hospital, Toronto, Canada (L.W., W.M.K.)
| | - Sandra Kwiek
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, Germany (N.U., M.S.); Institut für Pharmazie, Freie Universität Berlin, Berlin, Germany (S.K., J.R.); and The Keenan Research Centre of St. Michael's Hospital, Toronto, Canada (L.W., W.M.K.)
| | - Jörg Rademann
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, Germany (N.U., M.S.); Institut für Pharmazie, Freie Universität Berlin, Berlin, Germany (S.K., J.R.); and The Keenan Research Centre of St. Michael's Hospital, Toronto, Canada (L.W., W.M.K.)
| | - Wolfgang M Kuebler
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, Germany (N.U., M.S.); Institut für Pharmazie, Freie Universität Berlin, Berlin, Germany (S.K., J.R.); and The Keenan Research Centre of St. Michael's Hospital, Toronto, Canada (L.W., W.M.K.)
| | - Michael Schaefer
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, Germany (N.U., M.S.); Institut für Pharmazie, Freie Universität Berlin, Berlin, Germany (S.K., J.R.); and The Keenan Research Centre of St. Michael's Hospital, Toronto, Canada (L.W., W.M.K.)
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Kim YJ, Kang TC. The role of TRPC6 in seizure susceptibility and seizure-related neuronal damage in the rat dentate gyrus. Neuroscience 2015; 307:215-30. [PMID: 26327362 DOI: 10.1016/j.neuroscience.2015.08.054] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 08/18/2015] [Accepted: 08/22/2015] [Indexed: 11/29/2022]
Abstract
Transient receptor potential canonical channel-6 (TRPC6) forms Ca(2+)-permeable non-selective cation channels in neurons. Although TRPC6 plays an important role in neurite outgrowth and neuronal survival during development, TRPC6 expression profiles available to identify distinctive hippocampal neuronal damage and hippocampal excitability in epilepsy are less defined. As compared to normal animals, TRPC6 expression was down-regulated in chronic epileptic rats showing spontaneous recurrent seizures. TRPC6 knockdown increased seizure susceptibility, excitability ratio and paired-pulse inhibition in the dentate gyrus (DG) of normal animals. Furthermore, TRPC6 knockdown promoted programmed neuronal necrosis in dentate granule cells, but prevented it in CA1 and CA3 neurons following status epilepticus. The present data suggest for the first time that TRPC6 may inhibit seizure susceptibility and neuronal vulnerability in the rat DG.
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Affiliation(s)
- Y-J Kim
- Department of Anatomy and Neurobiology, Institute of Epilepsy Research, College of Medicine, Hallym University, Chunchon 200-702, South Korea
| | - T-C Kang
- Department of Anatomy and Neurobiology, Institute of Epilepsy Research, College of Medicine, Hallym University, Chunchon 200-702, South Korea.
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Zeng C, Tian F, Xiao B. TRPC Channels: Prominent Candidates of Underlying Mechanism in Neuropsychiatric Diseases. Mol Neurobiol 2014; 53:631-647. [DOI: 10.1007/s12035-014-9004-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 11/13/2014] [Indexed: 10/24/2022]
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Yi F, DeCan E, Stoll K, Marceau E, Deisseroth K, Lawrence JJ. Muscarinic excitation of parvalbumin-positive interneurons contributes to the severity of pilocarpine-induced seizures. Epilepsia 2014; 56:297-309. [PMID: 25495999 DOI: 10.1111/epi.12883] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/30/2014] [Indexed: 01/20/2023]
Abstract
OBJECTIVE A common rodent model in epilepsy research employs the muscarinic acetylcholine receptor (mAChR) agonist pilocarpine, yet the mechanisms underlying the induction of pilocarpine-induced seizures (PISs) remain unclear. Global M1 mAChR (M1 R) knockout mice are resistant to PISs, implying that M1 R activation disrupts excitation/inhibition balance. Parvalbumin-positive (PV) inhibitory neurons express M1 Rs, participate in cholinergically induced oscillations, and can enter a state of depolarization block (DB) during epileptiform activity. Here, we test the hypothesis that pilocarpine activation of M1 Rs expressed on PV cells contributes to PISs. METHODS CA1 PV cells in PV-CRE mice were visualized with a floxed YFP or hM3Dq-mCherry adeno-associated virus, or by crossing PV-CRE mice with the RosaYFP reporter line. To eliminate M1 Rs from PV cells, we generated PV-M1 knockout (KO) mice by crossing PV-CRE and floxed M1 mice. Action potential (AP) frequency was monitored during application of pilocarpine (200 μm). In behavioral experiments, locomotion and seizure symptoms were recorded in wild-type (WT) or PV-M1 KO mice during PISs. RESULTS Pilocarpine significantly increased AP frequency in CA1 PV cells into the gamma range. In the continued presence of pilocarpine, a subset (5/7) of PV cells progressed to DB, which was mimicked by hM3Dq activation of Gq-receptor signaling. Pilocarpine-induced depolarization, AP firing at gamma frequency, and progression to DB were prevented in CA1 PV cells of PV-M1 KO mice. Finally, compared to WT mice, PV-M1 KO mice were associated with reduced severity of PISs. SIGNIFICANCE Pilocarpine can directly depolarize PV+ cells via M1 R activation, but a subset of these cells progress to DB. Our electrophysiologic and behavioral results suggest that this mechanism is active during PISs, contributing to a collapse of PV-mediated γ-aminobutyric acid (GABA)ergic inhibition, dysregulation of excitation/inhibition balance, and increased susceptibility to PISs.
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Affiliation(s)
- Feng Yi
- COBRE Center for Structural and Functional Neuroscience, The University of Montana, Missoula, Montana, U.S.A; Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, Montana, U.S.A
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Zhang E, Liao P. Brain transient receptor potential channels and stroke. J Neurosci Res 2014; 93:1165-83. [PMID: 25502473 DOI: 10.1002/jnr.23529] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 09/10/2014] [Accepted: 11/04/2014] [Indexed: 02/06/2023]
Abstract
Transient receptor potential (TRP) channels have been increasingly implicated in the pathological mechanisms of CNS disorders. TRP expression has been detected in neurons, astrocytes, oligodendrocytes, microglia, and ependymal cells as well as in the cerebral vascular endothelium and smooth muscle. In stroke, TRPC3/4/6, TRPM2/4/7, and TRPV1/3/4 channels have been found to participate in ischemia-induced cell death, whereas other TRP channels, in particular those expressed in nonneuronal cells, have been less well studied. This review summarizes the current knowledge on the expression and functions of the TRP channels in various cell types in the brain and our current understanding of TRP channels in stroke pathophysiology. In an aging society, the occurrence of stroke is expected to increase steadily, and there is an urgent requirement to improve the current stroke management strategy. Therefore, elucidating the roles of TRP channels in stroke could shed light on the development of novel therapeutic strategies and ultimately improve stroke outcome.
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Affiliation(s)
- Eric Zhang
- Calcium Signalling Laboratory, National Neuroscience Institute, Singapore
| | - Ping Liao
- Calcium Signalling Laboratory, National Neuroscience Institute, Singapore.,Duke-NUS Graduate Medical School Singapore, Singapore
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