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Surdin T, Preissing B, Rohr L, Grömmke M, Böke H, Barcik M, Azimi Z, Jancke D, Herlitze S, Mark MD, Siveke I. Optogenetic activation of mGluR1 signaling in the cerebellum induces synaptic plasticity. iScience 2022; 26:105828. [PMID: 36632066 PMCID: PMC9826949 DOI: 10.1016/j.isci.2022.105828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 10/21/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Neuronal plasticity underlying cerebellar learning behavior is strongly associated with type 1 metabotropic glutamate receptor (mGluR1) signaling. Activation of mGluR1 leads to activation of the Gq/11 pathway, which is involved in inducing synaptic plasticity at the parallel fiber-Purkinje cell synapse (PF-PC) in form of long-term depression (LTD). To optogenetically modulate mGluR1 signaling we fused mouse melanopsin (OPN4) that activates the Gq/11 pathway to the C-termini of mGluR1 splice variants (OPN4-mGluR1a and OPN4-mGluR1b). Activation of both OPN4-mGluR1 variants showed robust Ca2+ increase in HEK cells and PCs of cerebellar slices. We provide the prove-of-concept approach to modulate synaptic plasticity via optogenetic activation of OPN4-mGluR1a inducing LTD at the PF-PC synapse in vitro. Moreover, we demonstrate that light activation of mGluR1a signaling pathway by OPN4-mGluR1a in PCs leads to an increase in intrinsic activity of PCs in vivo and improved cerebellum driven learning behavior.
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Affiliation(s)
- Tatjana Surdin
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
| | - Bianca Preissing
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
| | - Lennard Rohr
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
| | - Michelle Grömmke
- Behavioral Neuroscience, Ruhr-University Bochum, Bochum, Germany
| | - Hanna Böke
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
| | - Maike Barcik
- Cardiovascular Research Institute Düsseldorf, Division of Cardiology, Pulmonology, and Vascular Medicine, University Duesseldorf, Medical Faculty, Duesseldorf, Germany
| | - Zohre Azimi
- Optical Imaging Group, Institut für Neuroinformatik, Ruhr-University Bochum, Bochum, Germany
| | - Dirk Jancke
- Optical Imaging Group, Institut für Neuroinformatik, Ruhr-University Bochum, Bochum, Germany
| | - Stefan Herlitze
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany,Corresponding author
| | - Melanie D. Mark
- Behavioral Neuroscience, Ruhr-University Bochum, Bochum, Germany
| | - Ida Siveke
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany,Bridge Institute of Experimental Tumor Therapy, West German Cancer Center, University Hospital Essen, Essen, Germany,Corresponding author
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2
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Wu QW, Kapfhammer JP. The Emerging Key Role of the mGluR1-PKCγ Signaling Pathway in the Pathogenesis of Spinocerebellar Ataxias: A Neurodevelopmental Viewpoint. Int J Mol Sci 2022; 23:ijms23169169. [PMID: 36012439 PMCID: PMC9409119 DOI: 10.3390/ijms23169169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 12/19/2022] Open
Abstract
Spinocerebellar ataxias (SCAs) are a heterogeneous group of autosomal dominantly inherited progressive disorders with degeneration and dysfunction of the cerebellum. Although different subtypes of SCAs are classified according to the disease-associated causative genes, the clinical syndrome of the ataxia is shared, pointing towards a possible convergent pathogenic pathway among SCAs. In this review, we summarize the role of SCA-associated gene function during cerebellar Purkinje cell development and discuss the relationship between SCA pathogenesis and neurodevelopment. We will summarize recent studies on molecules involved in SCA pathogenesis and will focus on the mGluR1-PKCγ signaling pathway evaluating the possibility that this might be a common pathway which contributes to these diseases.
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3
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Debnath A, Williams PDE, Bamber BA. Reduced Ca2+ transient amplitudes may signify increased or decreased depolarization depending on the neuromodulatory signaling pathway. Front Neurosci 2022; 16:931328. [PMID: 35937887 PMCID: PMC9354622 DOI: 10.3389/fnins.2022.931328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/27/2022] [Indexed: 11/13/2022] Open
Abstract
Neuromodulators regulate neuronal excitability and bias neural circuit outputs. Optical recording of neuronal Ca2+ transients is a powerful approach to study the impact of neuromodulators on neural circuit dynamics. We are investigating the polymodal nociceptor ASH in Caenorhabditis elegans to better understand the relationship between neuronal excitability and optically recorded Ca2+ transients. ASHs depolarize in response to the aversive olfactory stimulus 1-octanol (1-oct) with a concomitant rise in somal Ca2+, stimulating an aversive locomotory response. Serotonin (5-HT) potentiates 1-oct avoidance through Gαq signaling, which inhibits L-type voltage-gated Ca2+ channels in ASH. Although Ca2+ signals in the ASH soma decrease, depolarization amplitudes increase because Ca2+ mediates inhibitory feedback control of membrane potential in this context. Here, we investigate octopamine (OA) signaling in ASH to assess whether this negative correlation between somal Ca2+ and depolarization amplitudes is a general phenomenon, or characteristic of certain neuromodulatory pathways. Like 5-HT, OA reduces somal Ca2+ transient amplitudes in ASH neurons. However, OA antagonizes 5-HT modulation of 1-oct avoidance behavior, suggesting that OA may signal through a different pathway. We further show that the pathway for OA diminution of ASH somal Ca2+ consists of the OCTR-1 receptor, the Go heterotrimeric G-protein, and the G-protein activated inwardly rectifying channels IRK-2 and IRK-3, and this pathway reduces depolarization amplitudes in parallel with somal Ca2+ transient amplitudes. Therefore, even within a single neuron, somal Ca2+ signal reduction may indicate either increased or decreased depolarization amplitude, depending on which neuromodulatory signaling pathways are activated, underscoring the need for careful interpretation of Ca2+ imaging data in neuromodulatory studies.
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Affiliation(s)
- Arunima Debnath
- Department of Biological Sciences, The University of Toledo, Toledo, OH, United States
| | - Paul D. E. Williams
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Bruce A. Bamber
- Department of Biological Sciences, The University of Toledo, Toledo, OH, United States
- *Correspondence: Bruce A. Bamber,
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4
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Burada AP, Vinnakota R, Lambolez B, Tricoire L, Kumar J. Structural biology of ionotropic glutamate delta receptors and their crosstalk with metabotropic glutamate receptors. Neuropharmacology 2021; 196:108683. [PMID: 34181979 DOI: 10.1016/j.neuropharm.2021.108683] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/31/2021] [Accepted: 06/17/2021] [Indexed: 10/21/2022]
Abstract
Enigmatic orphan glutamate delta receptors (GluD) are one of the four classes of the ionotropic glutamate receptors (iGluRs) that play key roles in synaptic transmission and plasticity. While members of other iGluR families viz AMPA, NMDA, and kainate receptors are gated by glutamate, the GluD receptors neither bind glutamate nor evoke ligand-induced currents upon binding of glycine and D-serine. Thus, the GluD receptors were considered to function as structural proteins that facilitate the formation, maturation, and maintenance of synapses in the hippocampus and cerebellum. Recent work has revealed that GluD receptors have extensive crosstalk with metabotropic glutamate receptors (mGlus) and are also gated by their activation. The latest development of a novel optopharamcological tool and the cryoEM structures of GluD receptors would help define the molecular and chemical basis of the GluD receptor's role in synaptic physiology. This article is part of the special Issue on "Glutamate Receptors - Orphan iGluRs".
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Affiliation(s)
- Ananth Prasad Burada
- Laboratory of Membrane Protein Biology, National Centre for Cell Science, NCCS Complex, S. P. Pune University, Pune, Maharashtra, 411007, India
| | - Rajesh Vinnakota
- Laboratory of Membrane Protein Biology, National Centre for Cell Science, NCCS Complex, S. P. Pune University, Pune, Maharashtra, 411007, India
| | - Bertrand Lambolez
- Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), CNRS, INSERM, Sorbonne Université, Paris, France
| | - Ludovic Tricoire
- Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), CNRS, INSERM, Sorbonne Université, Paris, France.
| | - Janesh Kumar
- Laboratory of Membrane Protein Biology, National Centre for Cell Science, NCCS Complex, S. P. Pune University, Pune, Maharashtra, 411007, India.
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5
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mGluR1 signaling in cerebellar Purkinje cells: Subcellular organization and involvement in cerebellar function and disease. Neuropharmacology 2021; 194:108629. [PMID: 34089728 DOI: 10.1016/j.neuropharm.2021.108629] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 05/19/2021] [Accepted: 05/20/2021] [Indexed: 11/20/2022]
Abstract
The cerebellum is essential for the control, coordination, and learning of movements, and for certain aspects of cognitive function. Purkinje cells are the sole output neurons in the cerebellar cortex and therefore play crucial roles in the diverse functions of the cerebellum. The type 1 metabotropic glutamate receptor (mGluR1) is prominently enriched in Purkinje cells and triggers downstream signaling pathways that are required for functional and structural plasticity, and for synaptic responses. To understand how mGluR1 contributes to cerebellar functions, it is important to consider not only the operational properties of this receptor, but also its spatial organization and the molecular interactions that enable its proper functioning. In this review, we highlight how mGluR1 and its related signaling molecules are organized into tightly coupled microdomains to fulfill physiological functions. We also describe emerging evidence that altered mGluR1 signaling in Purkinje cells underlies cerebellar dysfunction in ataxias of human patients and mouse models.
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6
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Chen-Engerer HJ, Hartmann J, Karl RM, Yang J, Feske S, Konnerth A. Two types of functionally distinct Ca 2+ stores in hippocampal neurons. Nat Commun 2019; 10:3223. [PMID: 31324793 PMCID: PMC6642203 DOI: 10.1038/s41467-019-11207-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 06/28/2019] [Indexed: 01/01/2023] Open
Abstract
It is widely assumed that inositol trisphosphate (IP3) and ryanodine (Ry) receptors share the same Ca2+ pool in central mammalian neurons. We now demonstrate that in hippocampal CA1 pyramidal neurons IP3- and Ry-receptors are associated with two functionally distinct intracellular Ca2+ stores, respectively. While the IP3-sensitive Ca2+ store refilling requires Orai2 channels, Ry-sensitive Ca2+ store refilling involves voltage-gated Ca2+ channels (VGCCs). Our findings have direct implications for the understanding of function and plasticity in these central mammalian neurons.
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Affiliation(s)
- Hsing-Jung Chen-Engerer
- Institute of Neuroscience, Technical University of Munich, Biedersteiner Str. 29, 80802, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy) and Center for Integrated Protein Sciences (CIPSM), Biedersteiner Str. 29, 80802, Munich, Germany
| | - Jana Hartmann
- Institute of Neuroscience, Technical University of Munich, Biedersteiner Str. 29, 80802, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy) and Center for Integrated Protein Sciences (CIPSM), Biedersteiner Str. 29, 80802, Munich, Germany
| | - Rosa Maria Karl
- Institute of Neuroscience, Technical University of Munich, Biedersteiner Str. 29, 80802, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy) and Center for Integrated Protein Sciences (CIPSM), Biedersteiner Str. 29, 80802, Munich, Germany
| | - Jun Yang
- Department of Pathology, School of Medicine, New York University, New York, NY, 10003, USA
| | - Stefan Feske
- Department of Pathology, School of Medicine, New York University, New York, NY, 10003, USA
| | - Arthur Konnerth
- Institute of Neuroscience, Technical University of Munich, Biedersteiner Str. 29, 80802, Munich, Germany.
- Munich Cluster for Systems Neurology (SyNergy) and Center for Integrated Protein Sciences (CIPSM), Biedersteiner Str. 29, 80802, Munich, Germany.
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7
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Key J, Mueller AK, Gispert S, Matschke L, Wittig I, Corti O, Münch C, Decher N, Auburger G. Ubiquitylome profiling of Parkin-null brain reveals dysregulation of calcium homeostasis factors ATP1A2, Hippocalcin and GNA11, reflected by altered firing of noradrenergic neurons. Neurobiol Dis 2019; 127:114-130. [PMID: 30763678 DOI: 10.1016/j.nbd.2019.02.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/05/2018] [Accepted: 02/08/2019] [Indexed: 02/06/2023] Open
Abstract
Parkinson's disease (PD) is the second most frequent neurodegenerative disorder in the old population. Among its monogenic variants, a frequent cause is a mutation in the Parkin gene (Prkn). Deficient function of Parkin triggers ubiquitous mitochondrial dysfunction and inflammation in the brain, but it remains unclear how selective neural circuits become vulnerable and finally undergo atrophy. We attempted to go beyond previous work, mostly done in peripheral tumor cells, which identified protein targets of Parkin activity, an ubiquitin E3 ligase. Thus, we now used aged Parkin-knockout (KO) mouse brain for a global quantification of ubiquitylated peptides by mass spectrometry (MS). This approach confirmed the most abundant substrate to be VDAC3, a mitochondrial outer membrane porin that modulates calcium flux, while uncovering also >3-fold dysregulations for neuron-specific factors. Ubiquitylation decreases were prominent for Hippocalcin (HPCA), Calmodulin (CALM1/CALML3), Pyruvate Kinase (PKM2), sodium/potassium-transporting ATPases (ATP1A1/2/3/4), the Rab27A-GTPase activating protein alpha (TBC1D10A) and an ubiquitin ligase adapter (DDB1), while strong increases occurred for calcium transporter ATP2C1 and G-protein subunits G(i)/G(o)/G(Tr). Quantitative immunoblots validated elevated abundance for the electrogenic pump ATP1A2, for HPCA as neuron-specific calcium sensor, which stimulates guanylate cyclases and modifies axonal slow afterhyperpolarization (sAHP), and for the calcium-sensing G-protein GNA11. We assessed if compensatory molecular regulations become insufficient over time, leading to functional deficits. Patch clamp experiments in acute Parkin-KO brain slices indeed revealed alterations of the electrophysiological properties in aged noradrenergic locus coeruleus (LC) neurons. LC neurons of aged Parkin-KO brain showed an acceleration of the spontaneous pacemaker frequency, a reduction in sAHP and shortening of action potential duration, without modulation of KCNQ potassium currents. These findings indicate altered calcium-dependent excitability in a PARK2 model of PD, mediated by diminished turnover of potential Parkin targets such as ATP1A2 and HPCA. The data also identified further novel Parkin substrate candidates like SIRT2, OTUD7B and CUL5. Our elucidation of neuron-specific mechanisms of PD pathogenesis helps to explain the known exceptional susceptibility of noradrenergic and dopaminergic projections to alterations of calcium homeostasis and its mitochondrial buffering.
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Affiliation(s)
- J Key
- Exp. Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - A K Mueller
- Institute for Physiology and Pathophysiology, Vegetative Physiology and Marburg Center for Mind, Brain and Behavior - MCMBB; Clinic for Neurology, Philipps-University Marburg, 35037 Marburg, Germany
| | - S Gispert
- Exp. Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - L Matschke
- Institute for Physiology and Pathophysiology, Vegetative Physiology and Marburg Center for Mind, Brain and Behavior - MCMBB; Clinic for Neurology, Philipps-University Marburg, 35037 Marburg, Germany
| | - I Wittig
- Functional Proteomics, SFB 815 Core Unit, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - O Corti
- Institut du Cerveau et de la Moelle épinière, ICM, Paris, F-75013, France; Inserm, U1127, Paris, F-75013, France; CNRS, UMR 7225, Paris, F-75013, France; Sorbonne Universités, Paris, F-75013, France
| | - C Münch
- Institute of Biochemistry II, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - N Decher
- Institute for Physiology and Pathophysiology, Vegetative Physiology and Marburg Center for Mind, Brain and Behavior - MCMBB; Clinic for Neurology, Philipps-University Marburg, 35037 Marburg, Germany.
| | - G Auburger
- Exp. Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany.
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8
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Naito R, Kassai H, Sakai Y, Schönherr S, Fukaya M, Schwarzer C, Sakagami H, Nakao K, Aiba A, Ferraguti F. New Features on the Expression and Trafficking of mGluR1 Splice Variants Exposed by Two Novel Mutant Mouse Lines. Front Mol Neurosci 2018; 11:439. [PMID: 30559646 PMCID: PMC6287019 DOI: 10.3389/fnmol.2018.00439] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 11/13/2018] [Indexed: 01/08/2023] Open
Abstract
Metabotropic glutamate receptors (mGluRs) couple to G-proteins to modulate slow synaptic transmission via intracellular second messengers. The first cloned mGluR, mGluR1, regulates motor coordination, synaptic plasticity and synapse elimination. mGluR1 undergoes alternative splicing giving rise to four translated variants that differ in their intracellular C-terminal domains. Our current knowledge about mGluR1 relates almost entirely to the long mGluR1α isoform, whereas little is known about the other shorter variants. To study the expression of mGluR1γ, we have generated by means of the CRISPR/Cas9 system a new knock-in (KI) mouse line in which the C-terminus of this variant carries two short tags. Using this mouse line, we could establish that mGluR1γ is either untranslated or in amounts that are undetectable in the mouse cerebellum, indicating that only mGluR1α and mGluR1β are present and active at cerebellar synapses. The trafficking and function of mGluR1 appear strongly influenced by adaptor proteins such as long Homers that bind to the C-terminus of mGluR1α. We generated a second transgenic (Tg) mouse line in which mGluR1α carries a point mutation in its Homer binding domain and studied whether disruption of this interaction influenced mGluR1 subcellular localization at cerebellar parallel fiber (PF)-Purkinje cell (PC) synapses by means of the freeze-fracture replica immunolabeling technique. These Tg animals did not show any overt behavioral phenotype, and despite the typical mGluR1 perisynaptic distribution was not significantly changed, we observed a higher probability of intrasynaptic diffusion suggesting that long Homers regulate the lateral mobility of mGluR1. We extended our ultrastructural analysis to other mouse lines in which only one mGluR1 variant was reintroduced in PC of mGluR1-knock out (KO) mice. This work revealed that mGluR1α preferentially accumulates closer to the edge of the postsynaptic density (PSD), whereas mGluR1β has a less pronounced perijunctional distribution and, in the absence of mGluR1α, its trafficking to the plasma membrane is impaired with an accumulation in intracellular organelles. In conclusion, our study sets several firm points on largely disputed matters, namely expression of mGluR1γ and role of the C-terminal domain of mGluR1 splice variants on their perisynaptic clustering.
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Affiliation(s)
- Rika Naito
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Hidetoshi Kassai
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Division of Molecular Genetics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yusuke Sakai
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Sabine Schönherr
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Masahiro Fukaya
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Japan
| | - Christoph Schwarzer
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Hiroyuki Sakagami
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Japan
| | - Kazuki Nakao
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Laboratory for Animal Resources and Genetic Engineering, RIKEN Center for Developmental Biology, Kobe, Japan
| | - Atsu Aiba
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Division of Molecular Genetics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Francesco Ferraguti
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
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9
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Wang Y, Han J, Chen X, Zeng X, Wang Y, Dong J, Chen J. Maternal iodine supplementation improves motor coordination in offspring by modulating the mGluR1 signaling pathway in mild iodine deficiency-induced hypothyroxinemia rats. J Nutr Biochem 2018; 58:80-89. [DOI: 10.1016/j.jnutbio.2018.04.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 04/17/2018] [Accepted: 04/22/2018] [Indexed: 02/02/2023]
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10
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Ca 2+ signaling and spinocerebellar ataxia. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1865:1733-1744. [PMID: 29777722 DOI: 10.1016/j.bbamcr.2018.05.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 05/07/2018] [Accepted: 05/09/2018] [Indexed: 11/22/2022]
Abstract
Spinocerebellar ataxia (SCA) is a neural disorder, which is caused by degenerative changes in the cerebellum. SCA is primarily characterized by gait ataxia, and additional clinical features include nystagmus, dysarthria, tremors and cerebellar atrophy. Forty-four hereditary SCAs have been identified to date, along with >35 SCA-associated genes. Despite the great diversity and distinct functionalities of the SCA-related genes, accumulating evidence supports the occurrence of a common pathophysiological event among several hereditary SCAs. Altered calcium (Ca2+) homeostasis in the Purkinje cells (PCs) of the cerebellum has been proposed as a possible pathological SCA trigger. In support of this, signaling events that are initiated from or lead to aberrant Ca2+ release from the type 1 inositol 1,4,5-trisphosphate receptor (IP3R1), which is highly expressed in cerebellar PCs, seem to be closely associated with the pathogenesis of several SCA types. In this review, we summarize the current research on pathological hereditary SCA events, which involve altered Ca2+ homeostasis in PCs, through IP3R1 signaling.
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11
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Meera P, Pulst S, Otis T. A positive feedback loop linking enhanced mGluR function and basal calcium in spinocerebellar ataxia type 2. eLife 2017; 6. [PMID: 28518055 PMCID: PMC5444899 DOI: 10.7554/elife.26377] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 05/16/2017] [Indexed: 12/11/2022] Open
Abstract
Metabotropic glutamate receptor 1 (mGluR1) function in Purkinje neurons (PNs) is essential for cerebellar development and for motor learning and altered mGluR1 signaling causes ataxia. Downstream of mGluR1, dysregulation of calcium homeostasis has been hypothesized as a key pathological event in genetic forms of ataxia but the underlying mechanisms remain unclear. We find in a spinocerebellar ataxia type 2 (SCA2) mouse model that calcium homeostasis in PNs is disturbed across a broad range of physiological conditions. At parallel fiber synapses, mGluR1-mediated excitatory postsynaptic currents (EPSCs) and associated calcium transients are increased and prolonged in SCA2 PNs. In SCA2 PNs, enhanced mGluR1 function is prevented by buffering [Ca2+] at normal resting levels while in wildtype PNs mGluR1 EPSCs are enhanced by elevated [Ca2+]. These findings demonstrate a deleterious positive feedback loop involving elevated intracellular calcium and enhanced mGluR1 function, a mechanism likely to contribute to PN dysfunction and loss in SCA2. DOI:http://dx.doi.org/10.7554/eLife.26377.001
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Affiliation(s)
- Pratap Meera
- Department of Neurobiology, Geffen School of Medicine, University of California, Los Angeles, United States
| | - Stefan Pulst
- Department of Neurology, University of Utah, Salt Lake, United States
| | - Thomas Otis
- Department of Neurobiology, Geffen School of Medicine, University of California, Los Angeles, United States.,Neuroscience, Ophthalmology, and Rare Diseases, Roche Pharmaceutical Research and Early Development, Basel, Switzerland
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12
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Hoxha E, Tempia F, Lippiello P, Miniaci MC. Modulation, Plasticity and Pathophysiology of the Parallel Fiber-Purkinje Cell Synapse. Front Synaptic Neurosci 2016; 8:35. [PMID: 27857688 PMCID: PMC5093118 DOI: 10.3389/fnsyn.2016.00035] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Accepted: 10/19/2016] [Indexed: 12/24/2022] Open
Abstract
The parallel fiber-Purkinje cell (PF-PC) synapse represents the point of maximal signal divergence in the cerebellar cortex with an estimated number of about 60 billion synaptic contacts in the rat and 100,000 billions in humans. At the same time, the Purkinje cell dendritic tree is a site of remarkable convergence of more than 100,000 parallel fiber synapses. Parallel fiber activity generates fast postsynaptic currents via α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, and slower signals, mediated by mGlu1 receptors, resulting in Purkinje cell depolarization accompanied by sharp calcium elevation within dendritic regions. Long-term depression (LTD) and long-term potentiation (LTP) have been widely described for the PF-PC synapse and have been proposed as mechanisms for motor learning. The mechanisms of induction for LTP and LTD involve different signaling mechanisms within the presynaptic terminal and/or at the postsynaptic site, promoting enduring modification in the neurotransmitter release and change in responsiveness to the neurotransmitter. The PF-PC synapse is finely modulated by several neurotransmitters, including serotonin, noradrenaline and acetylcholine. The ability of these neuromodulators to gate LTP and LTD at the PF-PC synapse could, at least in part, explain their effect on cerebellar-dependent learning and memory paradigms. Overall, these findings have important implications for understanding the cerebellar involvement in a series of pathological conditions, ranging from ataxia to autism. For example, PF-PC synapse dysfunctions have been identified in several murine models of spino-cerebellar ataxia (SCA) types 1, 3, 5 and 27. In some cases, the defect is specific for the AMPA receptor signaling (SCA27), while in others the mGlu1 pathway is affected (SCA1, 3, 5). Interestingly, the PF-PC synapse has been shown to be hyper-functional in a mutant mouse model of autism spectrum disorder, with a selective deletion of Pten in Purkinje cells. However, the full range of methodological approaches, that allowed the discovery of the physiological principles of PF-PC synapse function, has not yet been completely exploited to investigate the pathophysiological mechanisms of diseases involving the cerebellum. We, therefore, propose to extend the spectrum of experimental investigations to tackle this problem.
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Affiliation(s)
- Eriola Hoxha
- Neuroscience Institute Cavalieri Ottolenghi (NICO) and Department of Neuroscience, University of TorinoTorino, Italy
| | - Filippo Tempia
- Neuroscience Institute Cavalieri Ottolenghi (NICO) and Department of Neuroscience, University of TorinoTorino, Italy
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13
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John AE, Wilson MR, Habgood A, Porte J, Tatler AL, Stavrou A, Miele G, Jolly L, Knox AJ, Takata M, Offermanns S, Jenkins RG. Loss of epithelial Gq and G11 signaling inhibits TGFβ production but promotes IL-33-mediated macrophage polarization and emphysema. Sci Signal 2016; 9:ra104. [PMID: 27811142 DOI: 10.1126/scisignal.aad5568] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Heterotrimeric guanine nucleotide-binding protein (G protein) signaling links hundreds of G protein-coupled receptors with four G protein signaling pathways. Two of these, one mediated by Gq and G11 (Gq/11) and the other by G12 and G13 (G12/13), are implicated in the force-dependent activation of transforming growth factor-β (TGFβ) in lung epithelial cells. Reduced TGFβ activation in alveolar cells leads to emphysema, whereas enhanced TGFβ activation promotes acute lung injury and idiopathic pulmonary fibrosis. Therefore, precise control of alveolar TGFβ activation is essential for alveolar homeostasis. We investigated the involvement of the Gq/11 and G12/13 pathways in epithelial cells in generating active TGFβ and regulating alveolar inflammation. Mice deficient in both Gαq and Gα11 developed inflammation that was primarily caused by alternatively activated (M2-polarized) macrophages, enhanced matrix metalloproteinase 12 (MMP12) production, and age-related alveolar airspace enlargement consistent with emphysema. Mice with impaired Gq/11 signaling had reduced stretch-mediated generation of TGFβ by epithelial cells and enhanced macrophage MMP12 synthesis but were protected from the effects of ventilator-induced lung injury. Furthermore, synthesis of the cytokine interleukin-33 (IL-33) was increased in these alveolar epithelial cells, resulting in the M2-type polarization of alveolar macrophages independently of the effect on TGFβ. Our results suggest that alveolar Gq/11 signaling maintains alveolar homeostasis and likely independently increases TGFβ activation in response to the mechanical stress of the epithelium and decreases epithelial IL-33 synthesis. Together, these findings suggest that disruption of Gq/11 signaling promotes inflammatory emphysema but protects against mechanically induced lung injury.
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Affiliation(s)
- Alison E John
- Division of Respiratory Medicine, University of Nottingham, Nottingham, U.K.
| | - Michael R Wilson
- Department of Anaesthetics, Pain Medicine and Intensive Care, Imperial College, London, U.K
| | - Anthony Habgood
- Division of Respiratory Medicine, University of Nottingham, Nottingham, U.K
| | - Joanne Porte
- Division of Respiratory Medicine, University of Nottingham, Nottingham, U.K
| | - Amanda L Tatler
- Division of Respiratory Medicine, University of Nottingham, Nottingham, U.K
| | - Anastasios Stavrou
- Division of Respiratory Medicine, University of Nottingham, Nottingham, U.K
| | | | - Lisa Jolly
- Division of Respiratory Medicine, University of Nottingham, Nottingham, U.K
| | - Alan J Knox
- Division of Respiratory Medicine, University of Nottingham, Nottingham, U.K
| | - Masao Takata
- Department of Anaesthetics, Pain Medicine and Intensive Care, Imperial College, London, U.K
| | - Stefan Offermanns
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - R Gisli Jenkins
- Division of Respiratory Medicine, University of Nottingham, Nottingham, U.K
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Piochon C, Kano M, Hansel C. LTD-like molecular pathways in developmental synaptic pruning. Nat Neurosci 2016; 19:1299-310. [PMID: 27669991 PMCID: PMC5070480 DOI: 10.1038/nn.4389] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 07/27/2016] [Indexed: 02/06/2023]
Abstract
In long-term depression (LTD) at synapses in the adult brain, synaptic strength is reduced in an experience-dependent manner. LTD thus provides a cellular mechanism for information storage in some forms of learning. A similar activity-dependent reduction in synaptic strength also occurs in the developing brain and there provides an essential step in synaptic pruning and the postnatal development of neural circuits. Here we review evidence suggesting that LTD and synaptic pruning share components of their underlying molecular machinery and may thus represent two developmental stages of the same type of synaptic modulation that serve different, but related, functions in neural circuit plasticity. We also assess the relationship between LTD and synaptic pruning in the context of recent findings of LTD dysregulation in several mouse models of autism spectrum disorder (ASD) and discuss whether LTD deficits can indicate impaired pruning processes that are required for proper brain development.
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Affiliation(s)
- Claire Piochon
- Department of Neurobiology, University of Chicago, Chicago, Illinois, USA
- Department of Physiology, Northwestern University, Chicago, Illinois, USA
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Christian Hansel
- Department of Neurobiology, University of Chicago, Chicago, Illinois, USA
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15
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Kim JY, Kim N, Zheng Z, Lee JE, Yenari MA. 70-kDa Heat Shock Protein Downregulates Dynamin in Experimental Stroke: A New Therapeutic Target? Stroke 2016; 47:2103-11. [PMID: 27387989 DOI: 10.1161/strokeaha.116.012763] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 06/08/2016] [Indexed: 01/08/2023]
Abstract
BACKGROUND AND PURPOSE The 70-kDa heat shock protein (Hsp70) protects brain cells in models of cerebral ischemia. Proteomic screening of mice subjected to middle cerebral artery occlusion identified dynamin as a major downregulated protein in Hsp70-overexpressing mice (Hsp70 transgenic mice). Dynamin-1 is expressed in neurons and participates in neurotransmission, but also transports the death receptor Fas to the cell surface, where it can be bound by its ligand and lead to apoptosis. METHODS Mice were subjected to distal middle cerebral artery occlusion. Neuro-2a cells were subjected to oxygen glucose deprivation. Hsp70 transgenic and Hsp70-deficient (Hsp70 knockout) mice were compared with wild-type mice for histological and behavioral outcomes. Some mice and neuro-2a cell cultures were given dynasore, a dynamin inhibitor. RESULTS Hsp70 transgenic mice had better outcomes, whereas Hsp70 knockout mice had worse outcomes compared with wild-type mice. This correlated with decreased and increased dynamin expression, respectively. Dynamin colocalized to neurons and Fas, with higher Fas levels and increased caspase-8 expression. Hsp70 induction in neuro-2a cells was protected from oxygen glucose deprivation, while downregulating dynamin and Fas expression. Further, dynamin inhibition was found to be neuroprotective. CONCLUSIONS Dynamin may facilitate Fas-mediated apoptotic death in the brain, and Hsp70 may protect by preventing this trafficking. Dynamin should be explored as a new therapeutic target for neuroprotection.
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Affiliation(s)
- Jong Youl Kim
- From the Department of Neurology, UCSF and the SF Veterans Affairs Medical Center, CA (J.Y.K., N.K., Z.Z., M.A.Y.); and Department of Anatomy, BK21 Plus Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, ROK (J.E.L.)
| | - Nuri Kim
- From the Department of Neurology, UCSF and the SF Veterans Affairs Medical Center, CA (J.Y.K., N.K., Z.Z., M.A.Y.); and Department of Anatomy, BK21 Plus Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, ROK (J.E.L.)
| | - Zhen Zheng
- From the Department of Neurology, UCSF and the SF Veterans Affairs Medical Center, CA (J.Y.K., N.K., Z.Z., M.A.Y.); and Department of Anatomy, BK21 Plus Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, ROK (J.E.L.)
| | - Jong Eun Lee
- From the Department of Neurology, UCSF and the SF Veterans Affairs Medical Center, CA (J.Y.K., N.K., Z.Z., M.A.Y.); and Department of Anatomy, BK21 Plus Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, ROK (J.E.L.)
| | - Midori A Yenari
- From the Department of Neurology, UCSF and the SF Veterans Affairs Medical Center, CA (J.Y.K., N.K., Z.Z., M.A.Y.); and Department of Anatomy, BK21 Plus Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, ROK (J.E.L.).
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16
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Meera P, Pulst SM, Otis TS. Cellular and circuit mechanisms underlying spinocerebellar ataxias. J Physiol 2016; 594:4653-60. [PMID: 27198167 DOI: 10.1113/jp271897] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 03/13/2016] [Indexed: 12/12/2022] Open
Abstract
Degenerative ataxias are a common form of neurodegenerative disease that affect about 20 individuals per 100,000. The autosomal dominant spinocerebellar ataxias (SCAs) are caused by a variety of protein coding mutations (single nucleotide changes, deletions and expansions) in single genes. Affected genes encode plasma membrane and intracellular ion channels, membrane receptors, protein kinases, protein phosphatases and proteins of unknown function. Although SCA-linked genes are quite diverse they share two key features: first, they are highly, although not exclusively, expressed in cerebellar Purkinje neurons (PNs), and second, when mutated they lead ultimately to the degeneration of PNs. In this review we summarize ataxia-related changes in PN neurophysiology that have been observed in various mouse knockout lines and in transgenic models of human SCA. We also highlight emerging evidence that altered metabotropic glutamate receptor signalling and disrupted calcium homeostasis in PNs form a common, early pathophysiological mechanism in SCAs. Together these findings indicate that aberrant calcium signalling and profound changes in PN neurophysiology precede PN cell loss and are likely to lead to cerebellar circuit dysfunction that explains behavioural signs of ataxia characteristic of the disease.
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Affiliation(s)
- Pratap Meera
- Department of Neurobiology, Geffen School of Medicine, University of California, 650 Charles Young Drive, Los Angeles, CA, 90095, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, 175 N Medical Drive E, Salt Lake City, UT, 84132, USA
| | - Thomas S Otis
- Department of Neurobiology, Geffen School of Medicine, University of California, 650 Charles Young Drive, Los Angeles, CA, 90095, USA.,Roche Pharmaceutical Research and Early Development (pRED), Neuroscience, Ophthalmology and Rare Diseases (NORD), Grenzacherstrasse 124, CH-4070, Basel, Switzerland
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17
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Numb deficiency in cerebellar Purkinje cells impairs synaptic expression of metabotropic glutamate receptor and motor coordination. Proc Natl Acad Sci U S A 2015; 112:15474-9. [PMID: 26621723 DOI: 10.1073/pnas.1512915112] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein Numb, first identified as a cell-fate determinant in Drosophila, has been shown to promote the development of neurites in mammals and to be cotransported with endocytic receptors in clathrin-coated vesicles in vitro. Nevertheless, its function in mature neurons has not yet been elucidated. Here we show that cerebellar Purkinje cells (PCs) express high levels of Numb during adulthood and that conditional deletion of Numb in PCs is sufficient to impair motor coordination despite maintenance of a normal cerebellar cyto-architecture. Numb proved to be critical for internalization and recycling of metabotropic glutamate 1 receptor (mGlu1) in PCs. A significant decrease of mGlu1 and an inhibition of long-term depression at the parallel fiber-PC synapse were observed in conditional Numb knockout mice. Indeed, the trafficking of mGlu1 induced by agonists was inhibited significantly in these mutants, but the expression of ionotropic glutamate receptor subunits and of mGlu1-associated proteins was not affected by the loss of Numb. Moreover, transient and persistent forms of mGlu1 plasticity were robustly induced in mutant PCs, suggesting that they do not require mGlu1 trafficking. Together, our data demonstrate that Numb is a regulator for constitutive expression and dynamic transport of mGlu1.
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18
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Jarius S, Wildemann B. 'Medusa-head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 1: Anti-mGluR1, anti-Homer-3, anti-Sj/ITPR1 and anti-CARP VIII. J Neuroinflammation 2015; 12:166. [PMID: 26377085 PMCID: PMC4574226 DOI: 10.1186/s12974-015-0356-y] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 07/02/2015] [Indexed: 01/09/2023] Open
Abstract
Serological testing for anti-neural autoantibodies is important in patients presenting with idiopathic cerebellar ataxia, since these autoantibodies may indicate cancer, determine treatment and predict prognosis. While some of them target nuclear antigens present in all or most CNS neurons (e.g. anti-Hu, anti-Ri), others more specifically target antigens present in the cytoplasm or plasma membrane of Purkinje cells (PC). In this series of articles, we provide a detailed review of the clinical and paraclinical features, oncological, therapeutic and prognostic implications, pathogenetic relevance, and differential laboratory diagnosis of the 12 most common PC autoantibodies (often referred to as 'Medusa-head antibodies' due to their characteristic somatodendritic binding pattern when tested by immunohistochemistry). To assist immunologists and neurologists in diagnosing these disorders, typical high-resolution immunohistochemical images of all 12 reactivities are presented, diagnostic pitfalls discussed and all currently available assays reviewed. Of note, most of these antibodies target antigens involved in the mGluR1/calcium pathway essential for PC function and survival. Many of the antigens also play a role in spinocerebellar ataxia. Part 1 focuses on anti-metabotropic glutamate receptor 1-, anti-Homer protein homolog 3-, anti-Sj/inositol 1,4,5-trisphosphate receptor- and anti-carbonic anhydrase-related protein VIII-associated autoimmune cerebellar ataxia (ACA); part 2 covers anti-protein kinase C gamma-, anti-glutamate receptor delta-2-, anti-Ca/RhoGTPase-activating protein 26- and anti-voltage-gated calcium channel-associated ACA; and part 3 reviews the current knowledge on anti-Tr/delta notch-like epidermal growth factor-related receptor-, anti-Nb/AP3B2-, anti-Yo/cerebellar degeneration-related protein 2- and Purkinje cell antibody 2-associated ACA, discusses differential diagnostic aspects and provides a summary and outlook.
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Affiliation(s)
- S Jarius
- Molecular Neuroimmunology Group, Department of Neurology, University of Heidelberg, Otto Meyerhof Center, Im Neuenheimer Feld 350, D-69120, Heidelberg, Germany.
| | - B Wildemann
- Molecular Neuroimmunology Group, Department of Neurology, University of Heidelberg, Otto Meyerhof Center, Im Neuenheimer Feld 350, D-69120, Heidelberg, Germany.
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19
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Hartmann J, Konnerth A. TRPC3‐dependent synaptic transmission in central mammalian neurons. J Mol Med (Berl) 2015; 93:983-9. [DOI: 10.1007/s00109-015-1298-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 05/05/2015] [Accepted: 05/13/2015] [Indexed: 01/05/2023]
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20
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Huang Y, Thathiah A. Regulation of neuronal communication by G protein-coupled receptors. FEBS Lett 2015; 589:1607-19. [PMID: 25980603 DOI: 10.1016/j.febslet.2015.05.007] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/05/2015] [Accepted: 05/05/2015] [Indexed: 02/06/2023]
Abstract
Neuronal communication plays an essential role in the propagation of information in the brain and requires a precisely orchestrated connectivity between neurons. Synaptic transmission is the mechanism through which neurons communicate with each other. It is a strictly regulated process which involves membrane depolarization, the cellular exocytosis machinery, neurotransmitter release from synaptic vesicles into the synaptic cleft, and the interaction between ion channels, G protein-coupled receptors (GPCRs), and downstream effector molecules. The focus of this review is to explore the role of GPCRs and G protein-signaling in neurotransmission, to highlight the function of GPCRs, which are localized in both presynaptic and postsynaptic membrane terminals, in regulation of intrasynaptic and intersynaptic communication, and to discuss the involvement of astrocytic GPCRs in the regulation of neuronal communication.
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Affiliation(s)
- Yunhong Huang
- VIB Center for the Biology of Disease, Leuven, Belgium; Center for Human Genetics (CME) and Leuven Institute for Neurodegenerative Diseases (LIND), University of Leuven (KUL), Leuven, Belgium.
| | - Amantha Thathiah
- VIB Center for the Biology of Disease, Leuven, Belgium; Center for Human Genetics (CME) and Leuven Institute for Neurodegenerative Diseases (LIND), University of Leuven (KUL), Leuven, Belgium.
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21
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Lv MM, Cheng YC, Xiao ZB, Sun MY, Ren PC, Sun XD. Down-regulation of Homer1b/c attenuates group I metabotropic glutamate receptors dependent Ca²⁺ signaling through regulating endoplasmic reticulum Ca²⁺ release in PC12 cells. Biochem Biophys Res Commun 2014; 450:1568-74. [PMID: 25026550 DOI: 10.1016/j.bbrc.2014.07.044] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Accepted: 07/07/2014] [Indexed: 10/25/2022]
Abstract
The molecular basis for group I metabotropic glutamate receptors (mGluR1 and 5) coupling to membrane ion channels and intracellular calcium pools is not fully understood. Homer is a family of post synaptic density proteins functionally and physically attached to target proteins at proline-rich sequences. In the present study, we demonstrate that Homer1b/c is constitutively expressed in PC12 cells, whereas Homer1a, the immediate early gene product, can be up-regulated by brain derived neurotrophic factor (BDNF) and glutamate. Knockdown of Homer1b/c using specific target small interfering RNA (siRNA) did not interfere the expression of mGluR1, mGluR5 and their downstream effectors, including inositol-1,4,5-trisphosphate receptors (IP3R), phospholipase C (PLC) and Gq proteins. By analyzing Ca(2+) imaging in PC12 cells, we demonstrated that Homer1b/c is an essential regulator of the Ca(2+) release from the endoplasmic reticulum (ER) induced by the activation of group I mGluRs, IP3R and ryanodine receptors (RyR). Furthermore, the group I mGluRs activation-dependent refilling of the Ca(2+) stores in both resting and depolarizing conditions were strongly attenuated in the absence of Homer1b/c. Together, our results demonstrate that in PC12 cells Homer1b/c is a regulator of group I mGluRs related Ca(2+) homeostasis that is essential for the maintenance of normal Ca(2+) levels in the ER.
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Affiliation(s)
- Miao-Miao Lv
- Department of Anesthesiology, Tangdu Hospital of the Fourth Military Medical University, Xi'an, Shaanxi 710032, China; Department of Anesthesiology, The 323 Hospital of PLA, Xi'an, Shaanxi 710054, China
| | - Yong-Chun Cheng
- Department of Anesthesiology, The Third Hospital of PLA, Baoji, Shaanxi 721004, China
| | - Zhi-Bin Xiao
- Department of Anesthesiology, The 323 Hospital of PLA, Xi'an, Shaanxi 710054, China
| | - Mei-Yan Sun
- Department of Anesthesiology, Tangdu Hospital of the Fourth Military Medical University, Xi'an, Shaanxi 710032, China
| | - Peng-Cheng Ren
- Department of Anesthesiology, Tangdu Hospital of the Fourth Military Medical University, Xi'an, Shaanxi 710032, China
| | - Xu-De Sun
- Department of Anesthesiology, Tangdu Hospital of the Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
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22
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Hartmann J, Karl RM, Alexander RPD, Adelsberger H, Brill MS, Rühlmann C, Ansel A, Sakimura K, Baba Y, Kurosaki T, Misgeld T, Konnerth A. STIM1 controls neuronal Ca²⁺ signaling, mGluR1-dependent synaptic transmission, and cerebellar motor behavior. Neuron 2014; 82:635-44. [PMID: 24811382 DOI: 10.1016/j.neuron.2014.03.027] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/03/2014] [Indexed: 12/18/2022]
Abstract
In central mammalian neurons, activation of metabotropic glutamate receptor type1 (mGluR1) evokes a complex synaptic response consisting of IP3 receptor-dependent Ca(2+) release from internal Ca(2+) stores and a slow depolarizing potential involving TRPC3 channels. It is largely unclear how mGluR1 is linked to its downstream effectors. Here, we explored the role of stromal interaction molecule 1 (STIM1) in regulating neuronal Ca(2+) signaling and mGluR1-dependent synaptic transmission. By analyzing mouse cerebellar Purkinje neurons, we demonstrate that STIM1 is an essential regulator of the Ca(2+) level in neuronal endoplasmic reticulum Ca(2+) stores. Both mGluR1-dependent synaptic potentials and IP3 receptor-dependent Ca(2+) signals are strongly attenuated in the absence of STIM1. Furthermore, the Purkinje neuron-specific deletion of Stim1 causes impairments in cerebellar motor behavior. Together, our results demonstrate that in the mammalian nervous system STIM1 is a key regulator of intracellular Ca(2+) signaling, metabotropic glutamate receptor-dependent synaptic transmission, and motor coordination.
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Affiliation(s)
- Jana Hartmann
- Institute of Neuroscience, Technical University Munich, Biedersteiner Straße 29, 80802 Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Biedersteiner Straße 29, 80802 Munich, Germany
| | - Rosa M Karl
- Institute of Neuroscience, Technical University Munich, Biedersteiner Straße 29, 80802 Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Biedersteiner Straße 29, 80802 Munich, Germany
| | - Ryan P D Alexander
- Institute of Neuroscience, Technical University Munich, Biedersteiner Straße 29, 80802 Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Biedersteiner Straße 29, 80802 Munich, Germany
| | - Helmuth Adelsberger
- Institute of Neuroscience, Technical University Munich, Biedersteiner Straße 29, 80802 Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Biedersteiner Straße 29, 80802 Munich, Germany
| | - Monika S Brill
- Munich Cluster for Systems Neurology (SyNergy), Biedersteiner Straße 29, 80802 Munich, Germany; Center for Integrated Protein Sciences (CIPSM), Biedersteiner Straße 29, 80802 Munich, Germany; Chair for Biomolecular Sensors and German Center for Neurodegenerative Diseases (DZNE), Technical University Munich, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Charlotta Rühlmann
- Institute of Neuroscience, Technical University Munich, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Anna Ansel
- Institute of Neuroscience, Technical University Munich, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Kenji Sakimura
- Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Yoshihiro Baba
- Immunology Frontier Research Center, Osaka University, 9F Integrated Life Science Building, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Tomohiro Kurosaki
- Immunology Frontier Research Center, Osaka University, 9F Integrated Life Science Building, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Thomas Misgeld
- Munich Cluster for Systems Neurology (SyNergy), Biedersteiner Straße 29, 80802 Munich, Germany; Center for Integrated Protein Sciences (CIPSM), Biedersteiner Straße 29, 80802 Munich, Germany; Chair for Biomolecular Sensors and German Center for Neurodegenerative Diseases (DZNE), Technical University Munich, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Arthur Konnerth
- Institute of Neuroscience, Technical University Munich, Biedersteiner Straße 29, 80802 Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Biedersteiner Straße 29, 80802 Munich, Germany.
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23
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Sánchez-Fernández G, Cabezudo S, García-Hoz C, Benincá C, Aragay AM, Mayor F, Ribas C. Gαq signalling: the new and the old. Cell Signal 2014; 26:833-48. [PMID: 24440667 DOI: 10.1016/j.cellsig.2014.01.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 01/09/2014] [Indexed: 01/25/2023]
Abstract
In the last few years the interactome of Gαq has expanded considerably, contributing to improve our understanding of the cellular and physiological events controlled by this G alpha subunit. The availability of high-resolution crystal structures has led the identification of an effector-binding region within the surface of Gαq that is able to recognise a variety of effector proteins. Consequently, it has been possible to ascribe different Gαq functions to specific cellular players and to identify important processes that are triggered independently of the canonical activation of phospholipase Cβ (PLCβ), the first identified Gαq effector. Novel effectors include p63RhoGEF, that provides a link between G protein-coupled receptors and RhoA activation, phosphatidylinositol 3-kinase (PI3K), implicated in the regulation of the Akt pathway, or the cold-activated TRPM8 channel, which is directly inhibited upon Gαq binding. Recently, the activation of ERK5 MAPK by Gq-coupled receptors has also been described as a novel PLCβ-independent signalling axis that relies upon the interaction between this G protein and two novel effectors (PKCζ and MEK5). Additionally, the association of Gαq with different regulatory proteins can modulate its effector coupling ability and, therefore, its signalling potential. Regulators include accessory proteins that facilitate effector activation or, alternatively, inhibitory proteins that downregulate effector binding or promote signal termination. Moreover, Gαq is known to interact with several components of the cytoskeleton as well as with important organisers of membrane microdomains, which suggests that efficient signalling complexes might be confined to specific subcellular environments. Overall, the complex interaction network of Gαq underlies an ever-expanding functional diversity that puts forward this G alpha subunit as a major player in the control of physiological functions and in the development of different pathological situations.
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Affiliation(s)
- Guzmán Sánchez-Fernández
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain
| | - Sofía Cabezudo
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain
| | - Carlota García-Hoz
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain
| | | | - Anna M Aragay
- Department of Cell Biology, Molecular Biology Institute of Barcelona, Spain
| | - Federico Mayor
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain
| | - Catalina Ribas
- Departamento de Biología Molecular and Centro de Biologia Molecular "Severo Ochoa", CSIC-UAM, Universidad Autónoma de Madrid, Spain; Instituto de Investigación Sanitaria La Princesa, Madrid, Spain.
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24
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Wirotanseng LN, Kuner R, Tappe-Theodor A. Gq rather than G11 preferentially mediates nociceptor sensitization. Mol Pain 2013; 9:54. [PMID: 24156378 PMCID: PMC4016015 DOI: 10.1186/1744-8069-9-54] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 10/20/2013] [Indexed: 01/05/2023] Open
Abstract
Background The Gq/11-protein signaling mechanism is essential throughout the nervous system, but little is known about the contribution of the individual G-protein GPCR signaling branches towards nociceptor activation and their specific role on nociceptor sensitization. We aimed to unravel the contribution of the Gq/11-signaling pathway towards nociceptor activation via a variety of classical inflammatory mediators signalling via different G-protein GPCRs and investigated the specific contribution of the individual Gq and G11 G-Proteins in nociceptors. Findings Using different transgenic mouse lines, lacking Gαq, Gα11 or both α-subunit of the G-proteins in primary nociceptive neurons, we analyzed the mechanical- and heat-sensitivity upon application of different GPCR-agonists that are known to play an important role under inflammatory conditions (e.g. ATP, Glutamate, Serotonin etc.). We found that the Gq/11-GPCR signaling branch constitutes a primary role in the manifestation of mechanical allodynia and a minor role in the development of thermal hyperalgesia. Moreover, with respect to the mediators used here, the Gq-protein is the principle G-protein among the Gq/11-protein family in nociceptive neurons leading to nociceptor sensitization. Conclusions Our results demonstrate that the Gq/11 signaling branch plays a primary role in nociceptor sensitization upon stimulation with classical GPCR ligands, contributing primarily towards the development of mechanically allodynia. Moreover, the deletion of the individual G-proteins led to the finding that the Gq-protein dominates the signalling machinery of the Gq/11 family of G-proteins in nociceptive neurons.
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Affiliation(s)
| | | | - Anke Tappe-Theodor
- Pharmacology Institut, University of Heidelberg, Im Neuenheimer Feld 366, Heidelberg, D-69120, Germany.
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The actions of Pasteurella multocida toxin on neuronal cells. Neuropharmacology 2013; 77:9-18. [PMID: 24055502 PMCID: PMC3878393 DOI: 10.1016/j.neuropharm.2013.09.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 09/03/2013] [Accepted: 09/05/2013] [Indexed: 02/06/2023]
Abstract
Pasteurella multocida toxin (PMT) activates the G-proteins Gαi(1-3), Gαq, Gα11, Gα12 and Gα13 by deamidation of specific glutamine residues. A number of these alpha subunits have signalling roles in neurones. Hence we studied the action of this toxin on rat superior cervical ganglion (SCG) neurones and NG108-15 neuronal cells. Both Gαq and Gα11 could be identified in SCGs with immunocytochemistry. PMT had no direct action on Kv7 or Cav2 channels in SCGs. However PMT treatment enhanced muscarinic receptor mediated inhibition of M-current (Kv7.2 + 7. 3) as measured by a 19-fold leftward shift in the oxotremorine-M concentration–inhibition curve. Agonists of other receptors, such as bradykinin or angiotensin, that inhibit M-current did not produce this effect. However the amount of PIP2 hydrolysis could be enhanced by PMT for all three agonists. In a transduction system in SCGs that is unlikely to be affected by PMT, Go mediated inhibition of calcium current, PMT was ineffective whereas the response was blocked by pertussis toxin as expected. M1 muscarinic receptor evoked calcium mobilisation in transformed NG108-15 cells was enhanced by PMT. The calcium rises evoked by uridine triphosphate acting on endogenous P2Y2 receptors in NG108-15 cells were enhanced by PMT. The time and concentration dependence of the PMT effect was different for the resting calcium compared to the calcium rise produced by activation of P2Y2 receptors. PMT's action on these neuronal cells would suggest that if it got into the brain, symptoms of a hyperexcitable nature would be seen, such as seizures. Pasteurella multocida toxin (PMT) activates a range of G-protein alpha subunits. PMT increased muscarinic receptor mediated suppression of Kv7 potassium current in sympathetic neurones. PMT enhances both muscarinic and purinergic receptor mediated calcium mobilisation in NG108-15 cells. Both these events are mediated by the G-proteins Gq or G11. We would predict that the symptoms of central nervous system PMT toxicity would be hyperexcitable events such as seizures.
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Pamenter ME, Powell FL. Signalling mechanisms of long term facilitation of breathing with intermittent hypoxia. F1000PRIME REPORTS 2013; 5:23. [PMID: 23864930 PMCID: PMC3702218 DOI: 10.12703/p5-23] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Intermittent hypoxia causes long-term facilitation (LTF) of respiratory motor nerve activity and ventilation, which manifests as a persistent increase over the normoxic baseline for an hour or more after the acute hypoxic ventilatory response. LTF is likely involved in sleep apnea, but its exact role is uncertain. Previously, LTF was defined as a serotonergic mechanism, but new evidence shows that multiple signaling pathways can elicit LTF. This raises new questions about the interactions between signaling pathways in different time domains of the hypoxic ventilatory response, which can no longer be defined simply in terms of neurochemical mechanisms.
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Affiliation(s)
- Matthew E Pamenter
- Physiology Division, Department of Medicine, University of California San DiegoLa Jolla, CA 92092-0623USA
- Department of Zoology, University of British ColumbiaVancouver, BC V6T 1Z4Canada
| | - Frank L Powell
- Physiology Division, Department of Medicine, University of California San DiegoLa Jolla, CA 92092-0623USA
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Systematic profiling of Caenorhabditis elegans locomotive behaviors reveals additional components in G-protein Gαq signaling. Proc Natl Acad Sci U S A 2013; 110:11940-5. [PMID: 23818641 DOI: 10.1073/pnas.1310468110] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genetic screens have been widely applied to uncover genetic mechanisms of movement disorders. However, most screens rely on human observations of qualitative differences. Here we demonstrate the application of an automatic imaging system to conduct a quantitative screen for genes regulating the locomotive behavior in Caenorhabditis elegans. Two hundred twenty-seven neuronal signaling genes with viable homozygous mutants were selected for this study. We tracked and recorded each animal for 4 min and analyzed over 4,400 animals of 239 genotypes to obtain a quantitative, 10-parameter behavioral profile for each genotype. We discovered 87 genes whose inactivation causes movement defects, including 50 genes that had never been associated with locomotive defects. Computational analysis of the high-content behavioral profiles predicted 370 genetic interactions among these genes. Network partition revealed several functional modules regulating locomotive behaviors, including sensory genes that detect environmental conditions, genes that function in multiple types of excitable cells, and genes in the signaling pathway of the G protein Gαq, a protein that is essential for animal life and behavior. We developed quantitative epistasis analysis methods to analyze the locomotive profiles and validated the prediction of the γ isoform of phospholipase C as a component in the Gαq pathway. These results provided a system-level understanding of how neuronal signaling genes coordinate locomotive behaviors. This study also demonstrated the power of quantitative approaches in genetic studies.
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Glutamate receptor δ2 associates with metabotropic glutamate receptor 1 (mGluR1), protein kinase Cγ, and canonical transient receptor potential 3 and regulates mGluR1-mediated synaptic transmission in cerebellar Purkinje neurons. J Neurosci 2013; 32:15296-308. [PMID: 23115168 DOI: 10.1523/jneurosci.0705-12.2012] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cerebellar motor coordination and cerebellar Purkinje cell synaptic function require metabotropic glutamate receptor 1 (mGluR1, Grm1). We used an unbiased proteomic approach to identify protein partners for mGluR1 in cerebellum and discovered glutamate receptor δ2 (GluRδ2, Grid2, GluΔ2) and protein kinase Cγ (PKCγ) as major interactors. We also found canonical transient receptor potential 3 (TRPC3), which is also needed for mGluR1-dependent slow EPSCs and motor coordination and associates with mGluR1, GluRδ2, and PKCγ. Mutation of GluRδ2 changes subcellular fractionation of mGluR1 and TRPC3 to increase their surface expression. Fitting with this, mGluR1-evoked inward currents are increased in GluRδ2 mutant mice. Moreover, loss of GluRδ2 disrupts the time course of mGluR1-dependent synaptic transmission at parallel fiber-Purkinje cells synapses. Thus, GluRδ2 is part of the mGluR1 signaling complex needed for cerebellar synaptic function and motor coordination, explaining the shared cerebellar motor phenotype that manifests in mutants of the mGluR1 and GluRδ2 signaling pathways.
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Legate KR, Montag D, Böttcher RT, Takahashi S, Fässler R. Comparative phenotypic analysis of the two major splice isoforms of phosphatidylinositol phosphate kinase type Iγ in vivo. J Cell Sci 2012; 125:5636-46. [PMID: 22976293 DOI: 10.1242/jcs.102145] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Localized production of polyphosphoinositides is critical for their signaling function. To examine the biological relevance of specific pools of phosphatidylinositol 4,5-bisphosphate we compared the consequences of genetically ablating all isoforms of phosphatidylinositol phosphate (PIP) kinase type Iγ (PIPKIγ), encoded by the gene Pip5k1c, versus ablation of a specific splice isoform, PIPKIγ_i2, with respect to three reported PIPKIγ functions. Ablation of PIPKIγ_i2 caused a neuron-specific endocytosis defect similar to that found in PIPKIγ(-/-) mice, while agonist-induced calcium signaling was reduced in PIPKIγ(-/-) cells, but was not affected in the absence of PIPKIγ_i2. A reported contribution of PIPKIγ to epithelial integrity was not evident in PIPKIγ(-/-) mice. Given that mice lacking PIPKIγ_i2 live a normal lifespan whereas PIPKIγ(-/-) mice die shortly after birth, we propose that PIPKIγ-mediated metabotropic calcium signaling may represent an essential function of PIPKIγ, whereas functions specific to the PIPKIγ_i2 splice isoform are not essential for survival.
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Affiliation(s)
- Kyle R Legate
- Department of Molecular Medicine, Max Planck Institute of Biochemistry, Martinsried, 82152 Germany
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Subramanian N, Wetzel A, Dombert B, Yadav P, Havlicek S, Jablonka S, Nassar MA, Blum R, Sendtner M. Role of Nav1.9 in activity-dependent axon growth in motoneurons. Hum Mol Genet 2012; 21:3655-67. [DOI: 10.1093/hmg/dds195] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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31
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Tappe-Theodor A, Constantin CE, Tegeder I, Lechner SG, Langeslag M, Lepcynzsky P, Wirotanseng RI, Kurejova M, Agarwal N, Nagy G, Todd A, Wettschureck N, Offermanns S, Kress M, Lewin GR, Kuner R. Gαq/11 signaling tonically modulates nociceptor function and contributes to activity-dependent sensitization. Pain 2012; 153:184-196. [DOI: 10.1016/j.pain.2011.10.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 10/07/2011] [Accepted: 10/07/2011] [Indexed: 12/15/2022]
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Goto JI, Mikoshiba K. Inositol 1,4,5-Trisphosphate Receptor-Mediated Calcium Release in Purkinje Cells: From Molecular Mechanism to Behavior. THE CEREBELLUM 2011; 10:820-33. [DOI: 10.1007/s12311-011-0270-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Mitsumura K, Hosoi N, Furuya N, Hirai H. Disruption of metabotropic glutamate receptor signalling is a major defect at cerebellar parallel fibre-Purkinje cell synapses in staggerer mutant mice. J Physiol 2011; 589:3191-209. [PMID: 21558162 DOI: 10.1113/jphysiol.2011.207563] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Staggerer mutant mice have functional loss of a transcription factor, retinoid-related orphan receptor α (RORα), which is abundantly expressed in Purkinje cells (PCs) of the cerebellum.Homozygous staggerer (sg/sg)mice show cerebellar hypoplasia and congenital ataxia. Sg/sg mice serve as an important extreme mouse model of the hereditary spinocerebellar ataxia type 1 (SCA1), since it has been shown that RORα dysfunction is strongly correlated with SCA1 pathogenesis. However, synaptic abnormalities, especially at parallel fibre (PF)-PC synapses, in SCA1-related sg/sg mice have not been examined in detail electrophysiologically. In this study, we report that PFs can still establish functional synapses onto PCs in sg/sg mice in spite of reduction in the number of PF-PC synapses. Compared with PF-evoked EPSCs in the wild-type or heterozygotes, the success rate of the EPSC recordings in sg/sg was quite low (∼40%) and the EPSCs showed faster kinetics and slightly decreased paired pulse facilitation at short intervals. The prominent synaptic dysfunction is that sg/sg mice lack metabotropic glutamate receptor (mGluR)-mediated slow EPSCs completely. Neither intense PF stimulation nor an exogenously applied mGluR agonist, DHPG, could elicit mGluR-mediated responses.Western blot analysis in the sg/sg cerebellum revealed low-level expression of mGluR1 and TRPC3, both of which underlie mGluR-mediated slow currents in PCs. Immunohistochemical data demonstrated marked mislocalization of mGluR1 on sg/sg PCs.We found that mGluR-mediated retrograde suppression of PF-PC EPSCs by endocannabinoid is also impaired completely in sg/sg mice. These results suggest that disruption of mGluR signalling at PF-PC synapses is one of the major synaptic defects in sg/sg mice and may manifest itself in SCA1 pathology.
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Affiliation(s)
- Kazuhiro Mitsumura
- Department of Neurophysiology, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
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Hartmann J, Henning HA, Konnerth A. mGluR1/TRPC3-mediated Synaptic Transmission and Calcium Signaling in Mammalian Central Neurons. Cold Spring Harb Perspect Biol 2011; 3:cshperspect.a006726. [PMID: 21441586 DOI: 10.1101/cshperspect.a006726] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Metabotropic glutamate receptors type 1 (mGluR1s) are required for a normal function of the mammalian brain. They are particularly important for synaptic signaling and plasticity in the cerebellum. Unlike ionotropic glutamate receptors that mediate rapid synaptic transmission, mGluR1s produce in cerebellar Purkinje cells a complex postsynaptic response consisting of two distinct signal components, namely a local dendritic calcium signal and a slow excitatory postsynaptic potential. The basic mechanisms underlying these synaptic responses were clarified in recent years. First, the work of several groups established that the dendritic calcium signal results from IP(3) receptor-mediated calcium release from internal stores. Second, it was recently found that mGluR1-mediated slow excitatory postsynaptic potentials are mediated by the transient receptor potential channel TRPC3. This surprising finding established TRPC3 as a novel postsynaptic channel for glutamatergic synaptic transmission.
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Affiliation(s)
- Jana Hartmann
- Institute of Neuroscience and Center for Integrated Protein Science, Technical University of Munich, Germany.
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Auger C, Ogden D. AMPA receptor activation controls type I metabotropic glutamate receptor signalling via a tyrosine kinase at parallel fibre-Purkinje cell synapses. J Physiol 2010; 588:3063-74. [PMID: 20603338 DOI: 10.1113/jphysiol.2010.191080] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Metabotropic glutamate receptors type 1 (mGluR1s) and ionotropic AMPA receptors (AMPARs) are colocalized at parallel fibre (PF) to Purkinje cell synapses of the cerebellum. Single stimulation of PFs activates fast AMPAR excitatory postsynaptic currents, whereas the activation of mGluR1s requires burst stimulation. mGluR1s signal through several pathways in Purkinje cells and the most prominent is the activation of a slow EPSC (sEPSC). To separate the two synaptic currents, studies of the sEPSC have commonly been performed in the presence of AMPA/KA receptor antagonists. We show here in rat cerebellar slices that inhibition of the fast EPSC by AMPAR antagonists strongly and selectively potentiates the mGluR1 sEPSC, showing a negative regulation of mGluR1 by AMPAR. This effect is observed with low concentrations of NBQX (300 nM to 1 microM), with the selective AMPAR antagonist GYKI 53655 and also with gamma-DGG, a low affinity glutamate receptor antagonist. When photorelease of glutamate from MNI-glutamate was used to study the postsynaptic responses in isolation, AMPAR inhibition produced a similar potentiation of the mGluR1 sEPSC, showing that the interaction is postsynaptic. Finally, perfusion of the postsynaptic cell with PP1, an inhibitor of src-family tyrosine kinase, increased the amplitude of the mGluR1 sEPSC and occluded the effect of AMPAR inhibition. Thus, at PF to Purkinje cell synapses, AMPAR activation inhibits the mGluR1 sEPSC via activation of a src-family tyrosine kinase. Consequently mGluR1 signalling will be more sensitive to spillover of glutamate than to local synaptic release. Furthermore, it will be enhanced at silent PF synapses which are the majority in Purkinje cells.
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Affiliation(s)
- Céline Auger
- Laboratoire de Physiologie cérébrale, UMR8118, Université Paris Descartes, 45, rue des Saints Pères, 75006 Paris, France.
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GABAB Receptor-Mediated Modulation of Metabotropic Glutamate Signaling and Synaptic Plasticity in Central Neurons. GABABRECEPTOR PHARMACOLOGY - A TRIBUTE TO NORMAN BOWERY 2010; 58:149-73. [DOI: 10.1016/s1054-3589(10)58007-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Ferraguti F, Crepaldi L, Nicoletti F. Metabotropic glutamate 1 receptor: current concepts and perspectives. Pharmacol Rev 2009; 60:536-81. [PMID: 19112153 DOI: 10.1124/pr.108.000166] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Almost 25 years after the first report that glutamate can activate receptors coupled to heterotrimeric G-proteins, tremendous progress has been made in the field of metabotropic glutamate receptors. Now, eight members of this family of glutamate receptors, encoded by eight different genes that share distinctive structural features have been identified. The first cloned receptor, the metabotropic glutamate (mGlu) receptor mGlu1 has probably been the most extensively studied mGlu receptor, and in many respects it represents a prototypical subtype for this family of receptors. Its biochemical, anatomical, physiological, and pharmacological characteristics have been intensely investigated. Together with subtype 5, mGlu1 receptors constitute a subgroup of receptors that couple to phospholipase C and mobilize Ca(2+) from intracellular stores. Several alternatively spliced variants of mGlu1 receptors, which differ primarily in the length of their C-terminal domain and anatomical localization, have been reported. Use of a number of genetic approaches and the recent development of selective antagonists have provided a means for clarifying the role played by this receptor in a number of neuronal systems. In this article we discuss recent advancements in the pharmacology and concepts about the intracellular transduction and pathophysiological role of mGlu1 receptors and review earlier data in view of these novel findings. The impact that this new and better understanding of the specific role of these receptors may have on novel treatment strategies for a variety of neurological and psychiatric disorders is considered.
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Affiliation(s)
- Francesco Ferraguti
- Department of Pharmacology, Innsbruck Medical University, Peter-Mayr Strasse 1a, Innsbruck A-6020, Austria.
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Hartmann J, Konnerth A. Mechanisms of metabotropic glutamate receptor-mediated synaptic signalling in cerebellar Purkinje cells. Acta Physiol (Oxf) 2009. [DOI: 10.1111/j.1748-1716.2008.01923.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Tizzano M, Dvoryanchikov G, Barrows JK, Kim S, Chaudhari N, Finger TE. Expression of Galpha14 in sweet-transducing taste cells of the posterior tongue. BMC Neurosci 2008; 9:110. [PMID: 19014514 PMCID: PMC2596171 DOI: 10.1186/1471-2202-9-110] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2008] [Accepted: 11/13/2008] [Indexed: 12/03/2022] Open
Abstract
Background "Type II"/Receptor cells express G protein-coupled receptors (GPCRs) for sweet, umami (T1Rs and mGluRs) or bitter (T2Rs), as well as the proteins for downstream signalling cascades. Transduction downstream of T1Rs and T2Rs relies on G-protein and PLCβ2-mediated release of stored Ca2+. Whereas Gαgus (gustducin) couples to the T2R (bitter) receptors, which Gα-subunit couples to the sweet (T1R2 + T1R3) receptor is presently not known. We utilized RT-PCR, immunocytochemistry and single-cell gene expression profiling to examine the expression of the Gαq family (q, 11, 14) in mouse taste buds. Results By RT-PCR, Gα14 is expressed strongly and in a taste selective manner in posterior (vallate and foliate), but not anterior (fungiform and palate) taste fields. Gαq and Gα11, although detectable, are not expressed in a taste-selective fashion. Further, expression of Gα14 mRNA is limited to Type II/Receptor cells in taste buds. Immunocytochemistry on vallate papillae using a broad Gαq family antiserum reveals specific staining only in Type II taste cells (i.e. those expressing TrpM5 and PLCβ2). This staining persists in Gαq knockout mice and immunostaining with a Gα11-specific antiserum shows no immunoreactivity in taste buds. Taken together, these data show that Gα14 is the dominant Gαq family member detected. Immunoreactivity for Gα14 strongly correlates with expression of T1R3, the taste receptor subunit present in taste cells responsive to either umami or sweet. Single cell gene expression profiling confirms a tight correlation between the expression of Gα14 and both T1R2 and T1R3, the receptor combination that forms sweet taste receptors. Conclusion Gα14 is co-expressed with the sweet taste receptor in posterior tongue, although not in anterior tongue. Thus, sweet taste transduction may rely on different downstream transduction elements in posterior and anterior taste fields.
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Affiliation(s)
- Marco Tizzano
- Rocky Mountain Taste & Smell Center, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA.
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TRPC3 channels are required for synaptic transmission and motor coordination. Neuron 2008; 59:392-8. [PMID: 18701065 DOI: 10.1016/j.neuron.2008.06.009] [Citation(s) in RCA: 305] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Revised: 05/21/2008] [Accepted: 06/06/2008] [Indexed: 11/24/2022]
Abstract
In the mammalian central nervous system, slow synaptic excitation involves the activation of metabotropic glutamate receptors (mGluRs). It has been proposed that C1-type transient receptor potential (TRPC1) channels underlie this synaptic excitation, but our analysis of TRPC1-deficient mice does not support this hypothesis. Here, we show unambiguously that it is TRPC3 that is needed for mGluR-dependent synaptic signaling in mouse cerebellar Purkinje cells. TRPC3 is the most abundantly expressed TRPC subunit in Purkinje cells. In mutant mice lacking TRPC3, both slow synaptic potentials and mGluR-mediated inward currents are completely absent, while the synaptically mediated Ca2+ release signals from intracellular stores are unchanged. Importantly, TRPC3 knockout mice exhibit an impaired walking behavior. Taken together, our results establish TRPC3 as a new type of postsynaptic channel that mediates mGluR-dependent synaptic transmission in cerebellar Purkinje cells and is crucial for motor coordination.
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Kano M, Hashimoto K, Tabata T. Type-1 metabotropic glutamate receptor in cerebellar Purkinje cells: a key molecule responsible for long-term depression, endocannabinoid signalling and synapse elimination. Philos Trans R Soc Lond B Biol Sci 2008; 363:2173-86. [PMID: 18339599 DOI: 10.1098/rstb.2008.2270] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The cerebellum is a brain structure involved in the coordination, control and learning of movements, and elucidation of its function is an important issue. Japanese scholars have made seminal contributions in this field of neuroscience. Electrophysiological studies of the cerebellum have a long history in Japan since the pioneering works by Ito and Sasaki. Elucidation of the basic circuit diagram of the cerebellum in the 1960s was followed by the construction of cerebellar network theories and finding of their neural correlates in the 1970s. A theoretically predicted synaptic plasticity, long-term depression (LTD) at parallel fibre to Purkinje cell synapse, was demonstrated experimentally in 1982 by Ito and co-workers. Since then, Japanese neuroscientists from various disciplines participated in this field and have made major contributions to elucidate molecular mechanisms underlying LTD. An important pathway for LTD induction is type-1 metabotropic glutamate receptor (mGluR1) and its downstream signal transduction in Purkinje cells. Sugiyama and co-workers demonstrated the presence of mGluRs and Nakanishi and his pupils identified the molecular structures and functions of the mGluR family. Moreover, the authors contributed to the discovery and elucidation of several novel functions of mGluR1 in cerebellar Purkinje cells. mGluR1 turned out to be crucial for the release of endocannabinoid from Purkinje cells and the resultant retrograde suppression of transmitter release. It was also found that mGluR1 and its downstream signal transduction in Purkinje cells are indispensable for the elimination of redundant synapses during post-natal cerebellar development. This article overviews the seminal works by Japanese neuroscientists, focusing on mGluR1 signalling in cerebellar Purkinje cells.
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Affiliation(s)
- Masanobu Kano
- Department of Cellular Neuroscience, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan.
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Transient upregulation of postsynaptic IP3-gated Ca release underlies short-term potentiation of metabotropic glutamate receptor 1 signaling in cerebellar Purkinje cells. J Neurosci 2008; 28:4350-5. [PMID: 18434513 DOI: 10.1523/jneurosci.0284-08.2008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Synaptic plasticity lasting approximately 100 s has been suggested to function as a temporary buffer for neural information. One example of this was reported by Batchelor and Garthwaite (1997), who found that a slow metabotropic glutamate receptor 1 (mGluR1)-evoked EPSP produced by burst stimulation of cerebellar parallel fiber-Purkinje cell synapses could be potentiated by a conditioning stimulus consisting of prior activation of climbing fiber synapses (or injection of depolarizing current) with a delay of up to 90 s. What is the molecular basis of the signal that spans this temporal gap? Here, we show that mGluR1-evoked slow EPSCs evoked by parallel fiber burst test stimuli show a similar form of short-term potentiation (mGluR1-STP) and that this phenomenon is also observed when parallel fiber bursts are replaced by pressure pulses of an exogenous mGluR1 agonist. Ca imaging experiments revealed that cytosolic Ca levels returned to baseline within several seconds after conditioning depolarization, indicating that this cannot underlie mGluR1-STP. To test the hypothesis that transient upregulation of inositol-1,4,5-trisphosphate (IP(3))-gated Ca release underlies this phenomenon, we used local photolytic uncaging of IP(3) to deplete IP(3)-gated Ca stores. IP(3) uncaging in the interval between conditioning depolarization and the test pulse produced a complete blockade of mGluR1-STP, as did blockade of IP(3) receptors with heparin. When Ca transients evoked by IP(3) uncaging were used as a test stimulus, conditioning depolarization produced a large STP of Ca response amplitudes. These data suggest that transient upregulation of postsynaptic IP(3)-gated Ca signaling constitutes a novel form of short-term synaptic plasticity.
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Differential regulation of synaptic plasticity and cerebellar motor learning by the C-terminal PDZ-binding motif of GluRdelta2. J Neurosci 2008; 28:1460-8. [PMID: 18256267 DOI: 10.1523/jneurosci.2553-07.2008] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The delta2 glutamate receptor (GluRdelta2) is predominantly expressed in Purkinje cells and plays crucial roles in cerebellar functions: GluRdelta2-/- mice display ataxia and impaired motor learning. In addition, long-term depression (LTD) at parallel fiber (PF)-Purkinje cell synapses is abrogated, and synapse formation with PFs and climbing fibers (CFs) is severely disturbed in GluRdelta2-/- Purkinje cells. Recently, we demonstrated that abrogated LTD was restored in GluRdelta2-/- Purkinje cells by the virus-mediated expression of the wild-type GluRdelta2 transgene (Tg(wt)) but not by that of mutant GluRdelta2 lacking the C-terminal seven residues to which several PDZ proteins bind (Tg(DeltaCT7)). These results indicated that the C terminus of GluRdelta2 conveys the signal(s) necessary for LTD. In contrast, other phenotypes of GluRdelta2-/- cerebellum, especially morphological abnormalities at PF and CF synapses, could not be rescued by virus-mediated transient expression. Thus, whether these phenotypes are mediated by the same signaling pathway remains unclear. To address these issues and to further delineate the function of GluRdelta2 in vivo, we generated transgenic mice that expressed Tg(DeltaCT7) on a GluRdelta2-/- background. Interestingly, although Tg(DeltaCT7) restored abnormal PF and CF synapse formation almost completely, it could not rescue abrogated LTD in GluRdelta2-/- Purkinje cells. Furthermore, although the gross motor discoordination of GluRdelta2-/- mice was restored, the cerebellar motor learning underlying delayed eyeblink conditioning remained impaired. These results indicate that LTD induction and motor learning are regulated by signaling via the C-terminal end of GluRdelta2, whereas other functions may be differentially regulated by other regions of GluRdelta2.
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Ohkawa N, Hashimoto K, Hino T, Migishima R, Yokoyama M, Kano M, Inokuchi K. Motor discoordination of transgenic mice overexpressing a microtubule destabilizer, stathmin, specifically in Purkinje cells. Neurosci Res 2007; 59:93-100. [PMID: 17640754 DOI: 10.1016/j.neures.2007.06.1464] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Revised: 06/04/2007] [Accepted: 06/05/2007] [Indexed: 11/24/2022]
Abstract
The proper regulation of microtubule (MT) structure is important for dendritic and neural circuit development. However, the relationship between the regulation of the MTs in dendrites and the formation of neural function is still unclear. Stathmin is a MT destabilizer, and we have previously reported that the expression and the activity of stathmin is downregulated during cerebellar Purkinje cell (PC) development. In this study, we generated transgenic mice that specifically overexpress the constitutively active form of stathmin in the PCs. These mutant mice did not show any obvious morphological or excitatory transmission abnormalities in the cerebellum. In contrast, we observed a decline in the expression of MAP2 and KIF5 signal in the PC dendrites and a discoordination of motor function in the mutant mice, although they displayed normal general behavior. These data indicate that the overexpression of stathmin disrupts dendritic MT organization, motor protein distribution, and neural function in PCs.
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Affiliation(s)
- Noriaki Ohkawa
- Mitsubishi Kagaku Institute of Life Sciences, 11 Minamiooya, Machida, Tokyo 194-8511, Japan
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Jin Y, Kim SJ, Kim J, Worley PF, Linden DJ. Long-term depression of mGluR1 signaling. Neuron 2007; 55:277-87. [PMID: 17640528 PMCID: PMC2063510 DOI: 10.1016/j.neuron.2007.06.035] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Revised: 04/05/2007] [Accepted: 06/29/2007] [Indexed: 11/17/2022]
Abstract
Glutamate produces both fast excitation through activation of ionotropic receptors and slower actions through metabotropic receptors (mGluRs). To date, ionotropic but not metabotropic neurotransmission has been shown to undergo long-term synaptic potentiation and depression. Burst stimulation of parallel fibers releases glutamate, which activates perisynaptic mGluR1 in the dendritic spines of cerebellar Purkinje cells. Here, we show that the mGluR1-dependent slow EPSC and its coincident Ca transient were selectively and persistently depressed by repeated climbing fiber-evoked depolarization of Purkinje cells in brain slices. LTD(mGluR1) was also observed when slow synaptic current was evoked by exogenous application of a group I mGluR agonist, implying a postsynaptic expression mechanism. Ca imaging further revealed that LTD(mGluR1) was expressed as coincident attenuation of both limbs of mGluR1 signaling: the slow EPSC and PLC/IP3-mediated dendritic Ca mobilization. Thus, different patterns of neural activity can evoke LTD of either fast ionotropic or slow mGluR1-mediated synaptic signaling.
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Affiliation(s)
- Yunju Jin
- Department of Physiology, Seoul National University College of Medicine and Neuroscience Research Institute Medical Research Center, Korea
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Mameli M, Balland B, Luján R, Lüscher C. Rapid synthesis and synaptic insertion of GluR2 for mGluR-LTD in the ventral tegmental area. Science 2007; 317:530-3. [PMID: 17656725 DOI: 10.1126/science.1142365] [Citation(s) in RCA: 217] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The activation of metabotropic glutamate receptors (mGluRs) leads to long-term depression (mGluR-LTD) at many synapses of the brain. The induction of mGluR-LTD is well characterized, whereas the mechanisms underlying its expression remain largely elusive. mGluR-LTD in the ventral tegmental area (VTA) efficiently reverses cocaine-induced strengthening of excitatory inputs onto dopamine neurons. We show that mGluR-LTD is expressed by an exchange of GluR2-lacking AMPA receptors for GluR2-containing receptors with a lower single-channel conductance. The synaptic insertion of GluR2 depends on de novo protein synthesis via rapid messenger RNA translation of GluR2. Regulated synthesis of GluR2 in the VTA is therefore required to reverse cocaine-induced synaptic plasticity.
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Affiliation(s)
- Manuel Mameli
- Department of Basic Neuroscience, Medical Faculty, University of Geneva, CH-1211 Geneva, Switzerland
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Tabata T, Kawakami D, Hashimoto K, Kassai H, Yoshida T, Hashimotodani Y, Fredholm BB, Sekino Y, Aiba A, Kano M. G protein-independent neuromodulatory action of adenosine on metabotropic glutamate signalling in mouse cerebellar Purkinje cells. J Physiol 2007; 581:693-708. [PMID: 17379632 PMCID: PMC2075187 DOI: 10.1113/jphysiol.2007.129866] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Adenosine receptors (ARs) are G protein-coupled receptors (GPCRs) mediating the neuromodulatory actions of adenosine that influence emotional, cognitive, motor, and other functions in the central nervous system (CNS). Previous studies show complex formation between ARs and metabotropic glutamate receptors (mGluRs) in heterologous systems and close colocalization of ARs and mGluRs in several central neurons. Here we explored the possibility of intimate functional interplay between G(i/o) protein-coupled A(1)-subtype AR (A1R) and type-1 mGluR (mGluR1) naturally occurring in cerebellar Purkinje cells. Using a perforated-patch voltage-clamp technique, we found that both synthetic and endogenous agonists for A1R induced continuous depression of a mGluR1-coupled inward current. A1R agonists also depressed mGluR1-coupled intracellular Ca(2+) mobilization monitored by fluorometry. A1R indeed mediated this depression because genetic depletion of A1R abolished it. Surprisingly, A1R agonist-induced depression persisted after blockade of G(i/o) protein. The depression appeared to involve neither the cAMP-protein kinase A cascade downstream of the alpha subunits of G(i/o) and G(s) proteins, nor cytoplasmic Ca(2+) that is suggested to be regulated by the beta-gamma subunit complex of G(i/o) protein. Moreover, A1R did not appear to affect G(q) protein which mediates the mGluR1-coupled responses. These findings suggest that A1R modulates mGluR1 signalling without the aid of the major G proteins. In this respect, the A1R-mediated depression of mGluR1 signalling shown here is clearly distinguished from the A1R-mediated neuronal responses described so far. These findings demonstrate a novel neuromodulatory action of adenosine in central neurons.
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Affiliation(s)
- Toshihide Tabata
- Department of Cellular Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
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48
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Requirement of TrkB for synapse elimination in developing cerebellar Purkinje cells. ACTA ACUST UNITED AC 2007; 35:87-101. [PMID: 17940915 DOI: 10.1007/s11068-006-9002-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Revised: 11/14/2006] [Accepted: 11/15/2006] [Indexed: 12/21/2022]
Abstract
The receptor tyrosine kinase TrkB and its ligands, brain-derived neurotrophic factor (BDNF) and neurotrophin-4/5 (NT-4/5), are critically important for growth, survival and activity-dependent synaptic strengthening in the central nervous system. These TrkB-mediated actions occur in a highly cell-type specific manner. Here we report that cerebellar Purkinje cells, which are richly endowed with TrkB receptors, develop a normal morphology in trkB-deficient mice. Thus, in contrast to other types of neurons, Purkinje cells do not need TrkB for dendritic growth and spine formation. Instead, we find a moderate delay in the maturation of GABAergic synapses and, more importantly, an abnormal multiple climbing fiber innervation in Purkinje cells in trkB-deficient mice. Thus, our results demonstrate an involvement of TrkB receptors in synapse elimination and reveal a new role for receptor tyrosine kinases in the brain.
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Wettschureck N, van der Stelt M, Tsubokawa H, Krestel H, Moers A, Petrosino S, Schütz G, Di Marzo V, Offermanns S. Forebrain-specific inactivation of Gq/G11 family G proteins results in age-dependent epilepsy and impaired endocannabinoid formation. Mol Cell Biol 2006; 26:5888-94. [PMID: 16847339 PMCID: PMC1592765 DOI: 10.1128/mcb.00397-06] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Metabotropic receptors coupled to Gq/G11 family G proteins critically contribute to nervous system functions by modulating synaptic transmission, often facilitating excitation. We investigated the role of Gq/G11 family G proteins in the regulation of neuronal excitability in mice that selectively lack the alpha-subunits of Gq and G11, G alpha q and G alpha 11, respectively, in forebrain principal neurons. Surprisingly, mutant mice exhibited increased seizure susceptibility, and the activation of neuroprotective mechanisms was impaired. We found that endocannabinoid levels were reduced under both basal and excitotoxic conditions and that increased susceptibility to kainic acid could be normalized by the enhancement of endocannabinoid levels with an endocannabinoid reuptake inhibitor, while the competitive cannabinoid type 1 receptor antagonist SR141716A did not cause further aggravation. These findings indicate that Gq/G11 family G proteins negatively regulate neuronal excitability in vivo and suggest that impaired endocannabinoid formation in the absence of Gq/G11 contributes to this phenotype.
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Affiliation(s)
- Nina Wettschureck
- Institute of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
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Tabata T, Kano M. GABA(B) receptor-mediated modulation of glutamate signaling in cerebellar Purkinje cells. THE CEREBELLUM 2006; 5:127-33. [PMID: 16818387 DOI: 10.1080/14734220600788911] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Since Purkinje cells are the sole output neurons of the cerebellar cortex, the postsynaptic integration of excitatory and inhibitory synaptic inputs in this cell type is a pivotal step for cerebellar motor information processing. In Purkinje cells, Gi/o protein-coupled B-type gamma-aminobutyric acid receptor (GABABR) is expressed at the annuli of the dendritic spines that are innervated by the glutamatergic terminals of parallel fibers. The subcellular localization of GABABR suggests the possibility of postsynaptic interplay between GABABR and glutamate signaling. It has recently been demonstrated that GABABR indeed modulates alpha amino-3-hydroxy-5-methyl-4-isoxalone propionate-type ionotropic glutamate receptor (AMPAR)-mediated and type-1 metabotropic glutamate receptor (mGluR1)-mediated signaling. Interestingly, GABABR exerts modulatory actions not only via the classical Gi/o protein-dependent signaling cascade but also via a Gi/o protein-independent interaction between GABABR and mGluR1. In this review, we compare the physiological nature, underlying mechanisms, and possible functional significance of these modulatory actions of GABABR.
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Affiliation(s)
- Toshihide Tabata
- Department of Cellular Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
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