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Kakizawa S, Arasaki T, Yoshida A, Sato A, Takino Y, Ishigami A, Akaike T, Yanai S, Endo S. Essential role of ROS - 8-Nitro-cGMP signaling in long-term memory of motor learning and cerebellar synaptic plasticity. Redox Biol 2024; 70:103053. [PMID: 38340634 PMCID: PMC10869263 DOI: 10.1016/j.redox.2024.103053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 01/12/2024] [Accepted: 01/19/2024] [Indexed: 02/12/2024] Open
Abstract
Although reactive oxygen species (ROS) are known to have harmful effects in organisms, recent studies have demonstrated expression of ROS synthases at various parts of the organisms and the controlled ROS generation, suggesting possible involvement of ROS signaling in physiological events of individuals. However, physiological roles of ROS in the CNS, including functional roles in higher brain functions or neuronal activity-dependent ROS production, remain to be elucidated. Here, we demonstrated involvement of ROS - 8-NO2-cGMP signaling in motor learning and synaptic plasticity in the cerebellum. In the presence of inhibitors of ROS signal or ROS synthases, cerebellar motor learning was impaired, and the stimulus inducing long-term depression (LTD), cellular basis for the motor learning, failed to induce LTD but induced long-term potentiation (LTP)-like change at cerebellar synapses. Furthermore, ROS was produced by LTD-inducing stimulus in enzyme-dependent manner, and excess administration of the antioxidant vitamin E impaired cerebellar motor learning, suggesting beneficial roles of endogenous ROS in the learning. As a downstream signal, involvement of 8-NO2-cGMP in motor learning and cerebellar LTD were also revealed. These findings indicate that ROS - 8-NO2-cGMP signal is activated by neuronal activity and is essential for cerebellum-dependent motor learning and synaptic plasticity, demonstrating involvement of the signal in physiological function of brain systems.
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Affiliation(s)
- Sho Kakizawa
- Department of Biological Chemistry, Graduate School and Faculty of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan.
| | - Tomoko Arasaki
- Aging Neuroscience Research Team, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, 173-0015, Japan
| | - Ayano Yoshida
- Aging Neuroscience Research Team, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, 173-0015, Japan
| | - Ayami Sato
- Molecular Regulation of Aging, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, 173-0015, Japan
| | - Yuka Takino
- Molecular Regulation of Aging, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, 173-0015, Japan
| | - Akihito Ishigami
- Molecular Regulation of Aging, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, 173-0015, Japan
| | - Takaaki Akaike
- Department of Environmental Medicine and Molecular Toxicology, Tohoku University Graduate School of Medicine, Sendai, 980-8575, Japan
| | - Shuichi Yanai
- Aging Neuroscience Research Team, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, 173-0015, Japan
| | - Shogo Endo
- Aging Neuroscience Research Team, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, 173-0015, Japan.
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2
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Mitra R, Richhariya S, Hasan G. Orai-mediated calcium entry determines activity of central dopaminergic neurons by regulation of gene expression. eLife 2024; 12:RP88808. [PMID: 38289659 PMCID: PMC10945566 DOI: 10.7554/elife.88808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024] Open
Abstract
Maturation and fine-tuning of neural circuits frequently require neuromodulatory signals that set the excitability threshold, neuronal connectivity, and synaptic strength. Here, we present a mechanistic study of how neuromodulator-stimulated intracellular Ca2+ signals, through the store-operated Ca2+ channel Orai, regulate intrinsic neuronal properties by control of developmental gene expression in flight-promoting central dopaminergic neurons (fpDANs). The fpDANs receive cholinergic inputs for release of dopamine at a central brain tripartite synapse that sustains flight (Sharma and Hasan, 2020). Cholinergic inputs act on the muscarinic acetylcholine receptor to stimulate intracellular Ca2+ release through the endoplasmic reticulum (ER) localised inositol 1,4,5-trisphosphate receptor followed by ER-store depletion and Orai-mediated store-operated Ca2+ entry (SOCE). Analysis of gene expression in fpDANs followed by genetic, cellular, and molecular studies identified Orai-mediated Ca2+ entry as a key regulator of excitability in fpDANs during circuit maturation. SOCE activates the transcription factor trithorax-like (Trl), which in turn drives expression of a set of genes, including Set2, that encodes a histone 3 lysine 36 methyltransferase (H3K36me3). Set2 function establishes a positive feedback loop, essential for receiving neuromodulatory cholinergic inputs and sustaining SOCE. Chromatin-modifying activity of Set2 changes the epigenetic status of fpDANs and drives expression of key ion channel and signalling genes that determine fpDAN activity. Loss of activity reduces the axonal arborisation of fpDANs within the MB lobe and prevents dopamine release required for the maintenance of long flight.
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Affiliation(s)
- Rishav Mitra
- National Centre for Biological Sciences, Tata Institute of Fundamental ResearchBangaloreIndia
| | - Shlesha Richhariya
- National Centre for Biological Sciences, Tata Institute of Fundamental ResearchBangaloreIndia
- Department of Biology, Brandeis UniversityWalthamUnited States
| | - Gaiti Hasan
- National Centre for Biological Sciences, Tata Institute of Fundamental ResearchBangaloreIndia
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3
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Busch SE, Hansel C. Climbing fiber multi-innervation of mouse Purkinje dendrites with arborization common to human. Science 2023; 381:420-427. [PMID: 37499000 PMCID: PMC10962609 DOI: 10.1126/science.adi1024] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 06/16/2023] [Indexed: 07/29/2023]
Abstract
Canonically, each Purkinje cell (PC) in the adult cerebellum receives only one climbing fiber (CF) from the inferior olive. Underlying current theories of cerebellar function is the notion that this highly conserved one-to-one relationship renders Purkinje dendrites into a single computational compartment. However, we discovered that multiple primary dendrites are a near-universal morphological feature in humans. Using tract tracing, immunolabeling, and in vitro electrophysiology, we found that in mice ~25% of mature multibranched cells receive more than one CF input. Two-photon calcium imaging in vivo revealed that separate dendrites can exhibit distinct response properties to sensory stimulation, indicating that some multibranched cells integrate functionally independent CF-receptive fields. These findings indicate that PCs are morphologically and functionally more diverse than previously thought.
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Affiliation(s)
- Silas E. Busch
- Department of Neurobiology and Neuroscience Institute, University of Chicago, Chicago, IL 60637, USA
| | - Christian Hansel
- Department of Neurobiology and Neuroscience Institute, University of Chicago, Chicago, IL 60637, USA
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4
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Yadav P, Podia M, Kumari SP, Mani I. Glutamate receptor endocytosis and signaling in neurological conditions. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2023; 196:167-207. [PMID: 36813358 DOI: 10.1016/bs.pmbts.2022.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The non-essential amino acid glutamate acts as a major excitatory neurotransmitter and plays a significant role in the central nervous system (CNS). It binds with two different types of receptors, ionotropic glutamate receptors (iGluRs) and metabotropic glutamate receptors (mGluRs), responsible for the postsynaptic excitation of neurons. They are important for memory, neural development and communication, and learning. Endocytosis and subcellular trafficking of the receptor are essential for the regulation of receptor expression on the cell membrane and excitation of the cells. The endocytosis and trafficking of the receptor are dependent on its type, ligand, agonist, and antagonist present. This chapter discusses the types of glutamate receptors, their subtypes, and the regulation of their internalization and trafficking. The roles of glutamate receptors in neurological diseases are also briefly discussed.
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Affiliation(s)
- Prerna Yadav
- Department of Microbiology, University of Delhi, New Delhi, India
| | - Mansi Podia
- Department of Microbiology, University of Delhi, New Delhi, India
| | - Shashi Prabha Kumari
- Department of Microbiology, Ram Lal Anand College, University of Delhi, New Delhi, India
| | - Indra Mani
- Department of Microbiology, Gargi College, University of Delhi, New Delhi, India.
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5
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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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6
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Arjun McKinney A, Petrova R, Panagiotakos G. Calcium and activity-dependent signaling in the developing cerebral cortex. Development 2022; 149:276624. [PMID: 36102617 PMCID: PMC9578689 DOI: 10.1242/dev.198853] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Calcium influx can be stimulated by various intra- and extracellular signals to set coordinated gene expression programs into motion. As such, the precise regulation of intracellular calcium represents a nexus between environmental cues and intrinsic genetic programs. Mounting genetic evidence points to a role for the deregulation of intracellular calcium signaling in neuropsychiatric disorders of developmental origin. These findings have prompted renewed enthusiasm for understanding the roles of calcium during normal and dysfunctional prenatal development. In this Review, we describe the fundamental mechanisms through which calcium is spatiotemporally regulated and directs early neurodevelopmental events. We also discuss unanswered questions about intracellular calcium regulation during the emergence of neurodevelopmental disease, and provide evidence that disruption of cell-specific calcium homeostasis and/or redeployment of developmental calcium signaling mechanisms may contribute to adult neurological disorders. We propose that understanding the normal developmental events that build the nervous system will rely on gaining insights into cell type-specific calcium signaling mechanisms. Such an understanding will enable therapeutic strategies targeting calcium-dependent mechanisms to mitigate disease.
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Affiliation(s)
- Arpana Arjun McKinney
- University of California 1 Graduate Program in Developmental and Stem Cell Biology , , San Francisco, CA 94143 , USA
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California 2 , San Francisco, CA 94143 , USA
- University of California 3 Department of Biochemistry and Biophysics , , San Francisco, CA 94143 , USA
- Kavli Institute for Fundamental Neuroscience, University of California 4 , San Francisco, CA 94143 , USA
| | - Ralitsa Petrova
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California 2 , San Francisco, CA 94143 , USA
- University of California 3 Department of Biochemistry and Biophysics , , San Francisco, CA 94143 , USA
- Kavli Institute for Fundamental Neuroscience, University of California 4 , San Francisco, CA 94143 , USA
| | - Georgia Panagiotakos
- University of California 1 Graduate Program in Developmental and Stem Cell Biology , , San Francisco, CA 94143 , USA
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California 2 , San Francisco, CA 94143 , USA
- University of California 3 Department of Biochemistry and Biophysics , , San Francisco, CA 94143 , USA
- Kavli Institute for Fundamental Neuroscience, University of California 4 , San Francisco, CA 94143 , USA
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7
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O’Hare JK, Gonzalez KC, Herrlinger SA, Hirabayashi Y, Hewitt VL, Blockus H, Szoboszlay M, Rolotti SV, Geiller TC, Negrean A, Chelur V, Polleux F, Losonczy A. Compartment-specific tuning of dendritic feature selectivity by intracellular Ca 2+ release. Science 2022; 375:eabm1670. [PMID: 35298275 PMCID: PMC9667905 DOI: 10.1126/science.abm1670] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Dendritic calcium signaling is central to neural plasticity mechanisms that allow animals to adapt to the environment. Intracellular calcium release (ICR) from the endoplasmic reticulum has long been thought to shape these mechanisms. However, ICR has not been investigated in mammalian neurons in vivo. We combined electroporation of single CA1 pyramidal neurons, simultaneous imaging of dendritic and somatic activity during spatial navigation, optogenetic place field induction, and acute genetic augmentation of ICR cytosolic impact to reveal that ICR supports the establishment of dendritic feature selectivity and shapes integrative properties determining output-level receptive fields. This role for ICR was more prominent in apical than in basal dendrites. Thus, ICR cooperates with circuit-level architecture in vivo to promote the emergence of behaviorally relevant plasticity in a compartment-specific manner.
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Affiliation(s)
- Justin K. O’Hare
- Department of Neuroscience, Columbia University; New York, NY, 10027, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University; New York, NY, 10027, United States
| | - Kevin C. Gonzalez
- Department of Neuroscience, Columbia University; New York, NY, 10027, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University; New York, NY, 10027, United States
| | - Stephanie A. Herrlinger
- Department of Neuroscience, Columbia University; New York, NY, 10027, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University; New York, NY, 10027, United States
| | - Yusuke Hirabayashi
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo; Tokyo, Japan
| | - Victoria L. Hewitt
- Department of Neuroscience, Columbia University; New York, NY, 10027, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University; New York, NY, 10027, United States
| | - Heike Blockus
- Department of Neuroscience, Columbia University; New York, NY, 10027, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University; New York, NY, 10027, United States
| | - Miklos Szoboszlay
- Department of Neuroscience, Columbia University; New York, NY, 10027, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University; New York, NY, 10027, United States
| | - Sebi V. Rolotti
- Department of Neuroscience, Columbia University; New York, NY, 10027, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University; New York, NY, 10027, United States
| | - Tristan C. Geiller
- Department of Neuroscience, Columbia University; New York, NY, 10027, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University; New York, NY, 10027, United States
| | - Adrian Negrean
- Department of Neuroscience, Columbia University; New York, NY, 10027, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University; New York, NY, 10027, United States
| | - Vikas Chelur
- Department of Neuroscience, Columbia University; New York, NY, 10027, United States
| | - Franck Polleux
- Department of Neuroscience, Columbia University; New York, NY, 10027, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University; New York, NY, 10027, United States
- Kavli Institute for Brain Science, Columbia University; New York, NY, 10027, United States
| | - Attila Losonczy
- Department of Neuroscience, Columbia University; New York, NY, 10027, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University; New York, NY, 10027, United States
- Kavli Institute for Brain Science, Columbia University; New York, NY, 10027, United States
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8
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Cepeda-Prado EA, Khodaie B, Quiceno GD, Beythien S, Edelmann E, Lessmann V. Calcium-Permeable AMPA Receptors Mediate Timing-Dependent LTP Elicited by Low Repeat Coincident Pre- and Postsynaptic Activity at Schaffer Collateral-CA1 Synapses. Cereb Cortex 2021; 32:1682-1703. [PMID: 34498663 DOI: 10.1093/cercor/bhab306] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 07/26/2021] [Accepted: 07/28/2021] [Indexed: 12/26/2022] Open
Abstract
High-frequency stimulation induced long-term potentiation (LTP) and low-frequency stimulation induced LTD are considered as cellular models of memory formation. Interestingly, spike timing-dependent plasticity (STDP) can induce equally robust timing-dependent LTP (t-LTP) and t-LTD in response to low frequency repeats of coincident action potential (AP) firing in presynaptic and postsynaptic cells. Commonly, STDP paradigms relying on 25-100 repeats of coincident AP firing are used to elicit t-LTP or t-LTD, but the minimum number of repeats required for successful STDP is barely explored. However, systematic investigation of physiologically relevant low repeat STDP paradigms is of utmost importance to explain learning mechanisms in vivo. Here, we examined low repeat STDP at Schaffer collateral-CA1 synapses by pairing one presynaptic AP with either one postsynaptic AP (1:1 t-LTP), or a burst of 4 APs (1:4 t-LTP) and found 3-6 repeats to be sufficient to elicit t-LTP. 6× 1:1 t-LTP required postsynaptic Ca2+ influx via NMDARs and L-type VGCCs and was mediated by increased presynaptic glutamate release. In contrast, 1:4 t-LTP depended on postsynaptic metabotropic GluRs and ryanodine receptor signaling and was mediated by postsynaptic insertion of AMPA receptors. Unexpectedly, both 6× t-LTP variants were strictly dependent on activation of postsynaptic Ca2+-permeable AMPARs but were differentially regulated by dopamine receptor signaling. Our data show that synaptic changes induced by only 3-6 repeats of mild STDP stimulation occurring in ≤10 s can take place on time scales observed also during single trial learning.
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Affiliation(s)
- Efrain A Cepeda-Prado
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, Magdeburg 39120, Germany
| | - Babak Khodaie
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, Magdeburg 39120, Germany.,OVGU International ESF-funded Graduate School ABINEP, Magdeburg 39104, Germany
| | - Gloria D Quiceno
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, Magdeburg 39120, Germany
| | - Swantje Beythien
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, Magdeburg 39120, Germany
| | - Elke Edelmann
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, Magdeburg 39120, Germany.,OVGU International ESF-funded Graduate School ABINEP, Magdeburg 39104, Germany.,Center for Behavioral Brain Sciences, Magdeburg 39104, Germany
| | - Volkmar Lessmann
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, Magdeburg 39120, Germany.,OVGU International ESF-funded Graduate School ABINEP, Magdeburg 39104, Germany.,Center for Behavioral Brain Sciences, Magdeburg 39104, Germany
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9
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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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10
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Stochastic reaction-diffusion modeling of calcium dynamics in 3D dendritic spines of Purkinje cells. Biophys J 2021; 120:2112-2123. [PMID: 33887224 PMCID: PMC8390834 DOI: 10.1016/j.bpj.2021.03.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 02/22/2021] [Accepted: 03/18/2021] [Indexed: 02/07/2023] Open
Abstract
Calcium (Ca2+) is a second messenger assumed to control changes in synaptic strength in the form of both long-term depression and long-term potentiation at Purkinje cell dendritic spine synapses via inositol trisphosphate (IP3)-induced Ca2+ release. These Ca2+ transients happen in response to stimuli from parallel fibers (PFs) from granule cells and climbing fibers (CFs) from the inferior olivary nucleus. These events occur at low numbers of free Ca2+, requiring stochastic single-particle methods when modeling them. We use the stochastic particle simulation program MCell to simulate Ca2+ transients within a three-dimensional Purkinje cell dendritic spine. The model spine includes the endoplasmic reticulum, several Ca2+ transporters, and endogenous buffer molecules. Our simulations successfully reproduce properties of Ca2+ transients in different dynamical situations. We test two different models of the IP3 receptor (IP3R). The model with nonlinear concentration response of binding of activating Ca2+ reproduces experimental results better than the model with linear response because of the filtering of noise. Our results also suggest that Ca2+-dependent inhibition of the IP3R needs to be slow to reproduce experimental results. Simulations suggest the experimentally observed optimal timing window of CF stimuli arises from the relative timing of CF influx of Ca2+ and IP3 production sensitizing IP3R for Ca2+-induced Ca2+ release. We also model ataxia, a loss of fine motor control assumed to be the result of malfunctioning information transmission at the granule to Purkinje cell synapse, resulting in a decrease or loss of Ca2+ transients. Finally, we propose possible ways of recovering Ca2+ transients under ataxia.
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11
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TSUBOI M, HIRABAYASHI Y. New insights into the regulation of synaptic transmission and plasticity by the endoplasmic reticulum and its membrane contacts. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2021; 97:559-572. [PMID: 34897182 PMCID: PMC8687855 DOI: 10.2183/pjab.97.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 10/18/2021] [Indexed: 06/14/2023]
Abstract
Mammalian neurons are highly compartmentalized yet very large cells. To provide each compartment with its distinct properties, metabolic homeostasis and molecular composition need to be precisely coordinated in a compartment-specific manner. Despite the importance of the endoplasmic reticulum (ER) as a platform for various biochemical reactions, such as protein synthesis, protein trafficking, and intracellular calcium control, the contribution of the ER to neuronal compartment-specific functions and plasticity remains elusive. Recent advances in the development of live imaging and serial scanning electron microscopy (sSEM) analysis have revealed that the neuronal ER is a highly dynamic organelle with compartment-specific structures. sSEM studies also revealed that the ER forms contacts with other membranes, such as the mitochondria and plasma membrane, although little is known about the functions of these ER-membrane contacts. In this review, we discuss the mechanisms and physiological roles of the ER structure and ER-mitochondria contacts in synaptic transmission and plasticity, thereby highlighting a potential link between organelle ultrastructure and neuronal functions.
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Affiliation(s)
- Masafumi TSUBOI
- Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
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12
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Canepari M. Is Purkinje Neuron Hyperpolarisation Important for Cerebellar Synaptic Plasticity? A Retrospective and Prospective Analysis. THE CEREBELLUM 2020; 19:869-878. [PMID: 32654026 DOI: 10.1007/s12311-020-01164-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two recent studies have demonstrated that the dendritic Ca2+ signal associated with a climbing fibre (CF) input to the cerebellar Purkinje neuron (PN) depends on the membrane potential (Vm). Specifically, when the cell is hyperpolarised, this signal is mediated by T-type voltage-gated Ca2+ channels; in contrast, when the cell is firing, the CF-PN signal is mediated by P/Q-type voltage-gated Ca2+ channels. When the CF input is paired with parallel fibre (PF) activity, the signal is locally amplified at the sites of PF-activated synapses according to the Vm at the time of the CF input, suggesting that the standing Vm is a critical parameter for the induction of PF synaptic plasticity. In this review, I analyse how the Vm can potentially play a role in cerebellar learning focussing, in particular, on the hyperpolarised state that appears to occur episodically, since PNs are mostly firing under physiological conditions. By revisiting the recent literature reporting in vivo recordings and synaptic plasticity studies, I speculate on how a putative role of the PN Vm can provide an interpretation for the results of these studies.
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Affiliation(s)
- Marco Canepari
- University of Grenoble Alpes, CNRS, LIPhy, F-38000, Grenoble, France. .,Laboratories of Excellence, Ion Channel Science and Therapeutics, Valbonne, France. .,Institut National de la Santé et Recherche Médicale, Paris, France.
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13
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Bao J, Graupner M, Astorga G, Collin T, Jalil A, Indriati DW, Bradley J, Shigemoto R, Llano I. Synergism of type 1 metabotropic and ionotropic glutamate receptors in cerebellar molecular layer interneurons in vivo. eLife 2020; 9:56839. [PMID: 32401196 PMCID: PMC7220378 DOI: 10.7554/elife.56839] [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: 03/11/2020] [Accepted: 04/27/2020] [Indexed: 11/16/2022] Open
Abstract
Type 1 metabotropic glutamate receptors (mGluR1s) are key elements in neuronal signaling. While their function is well documented in slices, requirements for their activation in vivo are poorly understood. We examine this question in adult mice in vivo using 2-photon imaging of cerebellar molecular layer interneurons (MLIs) expressing GCaMP. In anesthetized mice, parallel fiber activation evokes beam-like Cai rises in postsynaptic MLIs which depend on co-activation of mGluR1s and ionotropic glutamate receptors (iGluRs). In awake mice, blocking mGluR1 decreases Cai rises associated with locomotion. In vitro studies and freeze-fracture electron microscopy show that the iGluR-mGluR1 interaction is synergistic and favored by close association of the two classes of receptors. Altogether our results suggest that mGluR1s, acting in synergy with iGluRs, potently contribute to processing cerebellar neuronal signaling under physiological conditions.
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Affiliation(s)
- Jin Bao
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France.,The Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China
| | - Michael Graupner
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Guadalupe Astorga
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Thibault Collin
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Abdelali Jalil
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Dwi Wahyu Indriati
- Division of Cerebral Structure, National Institute for Physiological Sciences, The Graduate University for Advanced Studies (Sokendai), Okazaki, Japan
| | - Jonathan Bradley
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France.,Institut de Biologie de l'Ecole Normale Superieure (IBENS), Ecole Normale Superieure, CNRS, INSERM, PSL Research University, Paris, France
| | - Ryuichi Shigemoto
- Division of Cerebral Structure, National Institute for Physiological Sciences, The Graduate University for Advanced Studies (Sokendai), Okazaki, Japan.,IST Austria, Klosterneuburg, Austria
| | - Isabel Llano
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
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14
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Influence of spatially segregated IP 3-producing pathways on spike generation and transmitter release in Purkinje cell axons. Proc Natl Acad Sci U S A 2020; 117:11097-11108. [PMID: 32358199 DOI: 10.1073/pnas.2000148117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
It has been known for a long time that inositol-trisphosphate (IP3) receptors are present in the axon of certain types of mammalian neurons, but their functional role has remained unexplored. Here we show that localized photolysis of IP3 induces spatially constrained calcium rises in Purkinje cell axons. Confocal immunohistology reveals that the axon initial segment (AIS), as well as terminals onto deep cerebellar cells, express specific subtypes of Gα/q and phospholipase C (PLC) molecules, together with the upstream purinergic receptor P2Y1. By contrast, intermediate parts of the axon express another set of Gα/q and PLC molecules, indicating two spatially segregated signaling cascades linked to IP3 generation. This prompted a search for distinct actions of IP3 in different parts of Purkinje cell axons. In the AIS, we found that local applications of the specific P2Y1R agonist MRS2365 led to calcium elevation, and that IP3 photolysis led to inhibition of action potential firing. In synaptic terminals on deep cerebellar nuclei neurons, we found that photolysis of both IP3 and ATP led to GABA release. We propose that axonal IP3 receptors can inhibit action potential firing and increase neurotransmitter release, and that these effects are likely controlled by purinergic receptors. Altogether our results suggest a rich and diverse functional role of IP3 receptors in axons of mammalian neurons.
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15
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Grossberg S. Developmental Designs and Adult Functions of Cortical Maps in Multiple Modalities: Perception, Attention, Navigation, Numbers, Streaming, Speech, and Cognition. Front Neuroinform 2020; 14:4. [PMID: 32116628 PMCID: PMC7016218 DOI: 10.3389/fninf.2020.00004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 01/16/2020] [Indexed: 11/13/2022] Open
Abstract
This article unifies neural modeling results that illustrate several basic design principles and mechanisms that are used by advanced brains to develop cortical maps with multiple psychological functions. One principle concerns how brains use a strip map that simultaneously enables one feature to be represented throughout its extent, as well as an ordered array of another feature at different positions of the strip. Strip maps include circuits to represent ocular dominance and orientation columns, place-value numbers, auditory streams, speaker-normalized speech, and cognitive working memories that can code repeated items. A second principle concerns how feature detectors for multiple functions develop in topographic maps, including maps for optic flow navigation, reinforcement learning, motion perception, and category learning at multiple organizational levels. A third principle concerns how brains exploit a spatial gradient of cells that respond at an ordered sequence of different rates. Such a rate gradient is found along the dorsoventral axis of the entorhinal cortex, whose lateral branch controls the development of time cells, and whose medial branch controls the development of grid cells. Populations of time cells can be used to learn how to adaptively time behaviors for which a time interval of hundreds of milliseconds, or several seconds, must be bridged, as occurs during trace conditioning. Populations of grid cells can be used to learn hippocampal place cells that represent the large spaces in which animals navigate. A fourth principle concerns how and why all neocortical circuits are organized into layers, and how functionally distinct columns develop in these circuits to enable map development. A final principle concerns the role of Adaptive Resonance Theory top-down matching and attentional circuits in the dynamic stabilization of early development and adult learning. Cortical maps are modeled in visual, auditory, temporal, parietal, prefrontal, entorhinal, and hippocampal cortices.
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Affiliation(s)
- Stephen Grossberg
- Center for Adaptive Systems, Graduate Program in Cognitive and Neural Systems, Departments of Mathematics & Statistics, Psychological & Brain Sciences, and Biomedical Engineering, Boston University, Boston, MA, United States
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16
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Takahashi S, Hanaoka K, Okubo Y, Echizen H, Ikeno T, Komatsu T, Ueno T, Hirose K, Iino M, Nagano T, Urano Y. Rational Design of a Near-infrared Fluorescence Probe for Ca 2+ Based on Phosphorus-substituted Rhodamines Utilizing Photoinduced Electron Transfer. Chem Asian J 2020; 15:524-530. [PMID: 31909880 DOI: 10.1002/asia.201901689] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Indexed: 12/12/2022]
Abstract
Fluorescence imaging in the near-infrared (NIR) region (650-900 nm) is useful for bioimaging because background autofluorescence is low and tissue penetration is high in this range. In addition, NIR fluorescence is useful as a complementary color window to green and red for multicolor imaging. Here, we compared the photoinduced electron transfer (PeT)-mediated fluorescence quenching of silicon- and phosphorus-substituted rhodamines (SiRs and PRs) in order to guide the development of improved far-red to NIR fluorescent dyes. The results of density functional theory calculations and photophysical evaluation of a series of newly synthesized PRs confirmed that the fluorescence of PRs was more susceptible than that of SiRs to quenching via PeT. Based on this, we designed and synthesized a NIR fluorescence probe for Ca2+ , CaPR-1, and its membrane-permeable acetoxymethyl derivative, CaPR-1 AM, which is distributed to the cytosol, in marked contrast to our previously reported Ca2+ far-red to NIR fluorescence probe based on the SiR scaffold, CaSiR-1 AM, which is mainly localized in lysosomes as well as cytosol in living cells. CaPR-1 showed longer-wavelength absorption and emission (up to 712 nm) than CaSiR-1. The new probe was able to image Ca2+ at dendrites and spines in brain slices, and should be a useful tool in neuroscience research.
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Affiliation(s)
- Shodai Takahashi
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Kenjiro Hanaoka
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yohei Okubo
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Honami Echizen
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Takayuki Ikeno
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Toru Komatsu
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Tasuku Ueno
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Kenzo Hirose
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Masamitsu Iino
- Division of Cellular and Molecular Pharmacology, Nihon University School of Medicine, 30-1 Oyaguchi kamicho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Tetsuo Nagano
- Drug Discovery Initiative, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yasuteru Urano
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.,Laboratory of Chemical Biology and Molecular Imaging, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.,AMED-CREST, Japan Agency for Medical Research and Development, 1-7-1 Otemachi, Chiyoda-ku, Tokyo, 100-0004, Japan
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17
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The Origin of Physiological Local mGluR1 Supralinear Ca 2+ Signals in Cerebellar Purkinje Neurons. J Neurosci 2020; 40:1795-1809. [PMID: 31969470 DOI: 10.1523/jneurosci.2406-19.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 01/09/2020] [Accepted: 01/11/2020] [Indexed: 11/21/2022] Open
Abstract
In mouse cerebellar Purkinje neurons (PNs), the climbing fiber (CF) input provides a signal to parallel fiber (PF) synapses, triggering PF synaptic plasticity. This signal is given by supralinear Ca2+ transients, associated with the CF synaptic potential and colocalized with the PF Ca2+ influx, occurring only when PF activity precedes the CF input. Here, we unravel the biophysical determinants of supralinear Ca2+ signals associated with paired PF-CF synaptic activity. We used membrane potential (V m) and Ca2+ imaging to investigate the local CF-associated Ca2+ influx following a train of PF synaptic potentials in two cases: (1) when the dendritic V m is hyperpolarized below the resting V m, and (2) when the dendritic V m is at rest. We found that supralinear Ca2+ signals are mediated by type-1 metabotropic glutamate receptors (mGluR1s) when the CF input is delayed by 100-150 ms from the first PF input in both cases. When the dendrite is hyperpolarized only, however, mGluR1s boost neighboring T-type channels, providing a mechanism for local coincident detection of PF-CF activity. The resulting Ca2+ elevation is locally amplified by saturation of endogenous Ca2+ buffers produced by the PF-associated Ca2+ influx via the mGluR1-mediated nonselective cation conductance. In contrast, when the dendritic V m is at rest, mGluR1s increase dendritic excitability by inactivating A-type K+ channels, but this phenomenon is not restricted to the activated PF synapses. Thus, V m is likely a crucial parameter in determining PF synaptic plasticity, and the occurrence of hyperpolarization episodes is expected to play an important role in motor learning.SIGNIFICANCE STATEMENT In Purkinje neurons, parallel fiber synaptic plasticity, determined by coincident activation of the climbing fiber input, underlies cerebellar learning. We unravel the biophysical mechanisms allowing the CF input to produce a local Ca2+ signal exclusively at the sites of activated parallel fibers. We show that when the membrane potential is hyperpolarized with respect to the resting membrane potential, type-1 metabotropic glutamate receptors locally enhance Ca2+ influx mediated by T-type Ca2+ channels, and that this signal is amplified by saturation of endogenous buffer also mediated by the same receptors. The combination of these two mechanisms is therefore capable of producing a Ca2+ signal at the activated parallel fiber sites, suggesting a role of Purkinje neuron membrane potential in cerebellar learning.
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18
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Stegner D, Hofmann S, Schuhmann MK, Kraft P, Herrmann AM, Popp S, Höhn M, Popp M, Klaus V, Post A, Kleinschnitz C, Braun A, Meuth SG, Lesch KP, Stoll G, Kraft R, Nieswandt B. Loss of Orai2-Mediated Capacitative Ca
2+
Entry Is Neuroprotective in Acute Ischemic Stroke. Stroke 2019; 50:3238-3245. [DOI: 10.1161/strokeaha.119.025357] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background and Purpose—
Ischemic stroke is one of the leading causes of disability and death. The principal goal of acute stroke treatment is the recanalization of the occluded cerebral arteries, which is, however, only effective in a very narrow time window. Therefore, neuroprotective treatments that can be combined with recanalization strategies are needed. Calcium overload is one of the major triggers of neuronal cell death. We have previously shown that capacitative Ca
2+
entry, which is triggered by the depletion of intracellular calcium stores, contributes to ischemia-induced calcium influx in neurons, but the responsible Ca
2+
channel is not known.
Methods—
Here, we have generated mice lacking the calcium channel subunit Orai2 and analyzed them in experimental stroke.
Results—
Orai2-deficient mice were protected from ischemic neuronal death both during acute ischemia under vessel occlusion and during ischemia/reperfusion upon successful recanalization. Calcium signals induced by calcium store depletion or oxygen/glucose deprivation were significantly diminished in Orai2-deficient neurons demonstrating that Orai2 is a central mediator of neuronal capacitative Ca
2+
entry and is involved in calcium overload during ischemia.
Conclusions—
Our experimental data identify Orai2 as an attractive target for pharmaceutical intervention in acute stroke.
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Affiliation(s)
- David Stegner
- From the Institute of Experimental Biomedicine, University Hospital Würzburg and Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Germany (D.S., S.H., M.P., V.K., A.B., B.N.)
| | - Sebastian Hofmann
- From the Institute of Experimental Biomedicine, University Hospital Würzburg and Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Germany (D.S., S.H., M.P., V.K., A.B., B.N.)
| | - Michael K. Schuhmann
- Department of Neurology, University Hospital Würzburg, Germany (M.K.S., P.K., G.S.)
| | - Peter Kraft
- Department of Neurology, University Hospital Würzburg, Germany (M.K.S., P.K., G.S.)
| | - Alexander M. Herrmann
- Department of Neurology with Institute of Translational Neurology, University Hospital Münster, Germany (A.M.H., C.K., S.G.M.)
| | - Sandy Popp
- Division of Molecular Psychiatry, Center of Mental Health, University of Würzburg, Germany (S.P., A.P., K.-P.L.)
| | - Marlen Höhn
- Carl-Ludwig-Institute for Physiology, University of Leipzig, Germany (M.H., R.K.)
| | - Michael Popp
- From the Institute of Experimental Biomedicine, University Hospital Würzburg and Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Germany (D.S., S.H., M.P., V.K., A.B., B.N.)
| | - Vanessa Klaus
- From the Institute of Experimental Biomedicine, University Hospital Würzburg and Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Germany (D.S., S.H., M.P., V.K., A.B., B.N.)
| | - Antonia Post
- Division of Molecular Psychiatry, Center of Mental Health, University of Würzburg, Germany (S.P., A.P., K.-P.L.)
| | - Christoph Kleinschnitz
- Department of Neurology with Institute of Translational Neurology, University Hospital Münster, Germany (A.M.H., C.K., S.G.M.)
- Department of Neurology, University Hospital Essen, Germany (C.K.)
| | - Attila Braun
- From the Institute of Experimental Biomedicine, University Hospital Würzburg and Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Germany (D.S., S.H., M.P., V.K., A.B., B.N.)
| | - Sven G. Meuth
- Department of Neurology with Institute of Translational Neurology, University Hospital Münster, Germany (A.M.H., C.K., S.G.M.)
| | - Klaus-Peter Lesch
- Division of Molecular Psychiatry, Center of Mental Health, University of Würzburg, Germany (S.P., A.P., K.-P.L.)
- Laboratory of Psychiatric Neurobiology, Institute of Molecular Medicine, I.M. Sechenov First Moscow State Medical University, Russia (K.-P.L.)
- Department of Neuroscience, School for Mental Health and Neuroscience (MHeNS), Maastricht University, the Netherlands (K.-P.L.)
| | - Guido Stoll
- Department of Neurology, University Hospital Würzburg, Germany (M.K.S., P.K., G.S.)
| | - Robert Kraft
- Carl-Ludwig-Institute for Physiology, University of Leipzig, Germany (M.H., R.K.)
| | - Bernhard Nieswandt
- From the Institute of Experimental Biomedicine, University Hospital Würzburg and Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Germany (D.S., S.H., M.P., V.K., A.B., B.N.)
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19
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Grossberg S. The Embodied Brain of SOVEREIGN2: From Space-Variant Conscious Percepts During Visual Search and Navigation to Learning Invariant Object Categories and Cognitive-Emotional Plans for Acquiring Valued Goals. Front Comput Neurosci 2019; 13:36. [PMID: 31333437 PMCID: PMC6620614 DOI: 10.3389/fncom.2019.00036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 05/21/2019] [Indexed: 11/13/2022] Open
Abstract
This article develops a model of how reactive and planned behaviors interact in real time. Controllers for both animals and animats need reactive mechanisms for exploration, and learned plans to efficiently reach goal objects once an environment becomes familiar. The SOVEREIGN model embodied these capabilities, and was tested in a 3D virtual reality environment. Neural models have characterized important adaptive and intelligent processes that were not included in SOVEREIGN. A major research program is summarized herein by which to consistently incorporate them into an enhanced model called SOVEREIGN2. Key new perceptual, cognitive, cognitive-emotional, and navigational processes require feedback networks which regulate resonant brain states that support conscious experiences of seeing, feeling, and knowing. Also included are computationally complementary processes of the mammalian neocortical What and Where processing streams, and homologous mechanisms for spatial navigation and arm movement control. These include: Unpredictably moving targets are tracked using coordinated smooth pursuit and saccadic movements. Estimates of target and present position are computed in the Where stream, and can activate approach movements. Motion cues can elicit orienting movements to bring new targets into view. Cumulative movement estimates are derived from visual and vestibular cues. Arbitrary navigational routes are incrementally learned as a labeled graph of angles turned and distances traveled between turns. Noisy and incomplete visual sensor data are transformed into representations of visual form and motion. Invariant recognition categories are learned in the What stream. Sequences of invariant object categories are stored in a cognitive working memory, whereas sequences of movement positions and directions are stored in a spatial working memory. Stored sequences trigger learning of cognitive and spatial/motor sequence categories or plans, also called list chunks, which control planned decisions and movements toward valued goal objects. Predictively successful list chunk combinations are selectively enhanced or suppressed via reinforcement learning and incentive motivational learning. Expected vs. unexpected event disconfirmations regulate these enhancement and suppressive processes. Adaptively timed learning enables attention and action to match task constraints. Social cognitive joint attention enables imitation learning of skills by learners who observe teachers from different spatial vantage points.
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Affiliation(s)
- Stephen Grossberg
- Center for Adaptive Systems, Graduate Program in Cognitive and Neural Systems, Departments of Mathematics & Statistics, Psychological & Brain Sciences, and Biomedical Engineering, Boston University, Boston, MA, United States
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20
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Eickelbeck D, Karapinar R, Jack A, Suess ST, Barzan R, Azimi Z, Surdin T, Grömmke M, Mark MD, Gerwert K, Jancke D, Wahle P, Spoida K, Herlitze S. CaMello-XR enables visualization and optogenetic control of G q/11 signals and receptor trafficking in GPCR-specific domains. Commun Biol 2019; 2:60. [PMID: 30793039 PMCID: PMC6376006 DOI: 10.1038/s42003-019-0292-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 01/09/2019] [Indexed: 12/20/2022] Open
Abstract
The signal specificity of G protein-coupled receptors (GPCRs) including serotonin receptors (5-HT-R) depends on the trafficking and localization of the GPCR within its subcellular signaling domain. Visualizing traffic-dependent GPCR signals in neurons is difficult, but important to understand the contribution of GPCRs to synaptic plasticity. We engineered CaMello (Ca2+-melanopsin-local-sensor) and CaMello-5HT2A for visualization of traffic-dependent Ca2+ signals in 5-HT2A-R domains. These constructs consist of the light-activated Gq/11 coupled melanopsin, mCherry and GCaMP6m for visualization of Ca2+ signals and receptor trafficking, and the 5-HT2A C-terminus for targeting into 5-HT2A-R domains. We show that the specific localization of the GPCR to its receptor domain drastically alters the dynamics and localization of the intracellular Ca2+ signals in different neuronal populations in vitro and in vivo. The CaMello method may be extended to every GPCR coupling to the Gq/11 pathway to help unravel new receptor-specific functions in respect to synaptic plasticity and GPCR localization. Dennis Eickelbeck et al. engineered light-activated constructs, CaMello and CaMello-5HT2A, which are targeted to the 5HT2A-R domains and enable visualization of calcium signals and receptor trafficking in response to activation. The reported CaMello tool could be applied to other GPCRs coupled to the Gq/11 signaling pathways which may shed light on mechanisms of GPCR localization and plasticity.
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Affiliation(s)
- Dennis Eickelbeck
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Raziye Karapinar
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Alexander Jack
- Developmental Neurobiology, ND6/72, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Sandra T Suess
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Ruxandra Barzan
- Optical Imaging Group, Institut für Neuroinformatik, NB 2/27, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Zohre Azimi
- Optical Imaging Group, Institut für Neuroinformatik, NB 2/27, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Tatjana Surdin
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Michelle Grömmke
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Melanie D Mark
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Klaus Gerwert
- Department of Biophysics, ND04/596, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Dirk Jancke
- Optical Imaging Group, Institut für Neuroinformatik, NB 2/27, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Petra Wahle
- Developmental Neurobiology, ND6/72, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Katharina Spoida
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Stefan Herlitze
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany.
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21
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Gq-Coupled Muscarinic Receptor Enhancement of KCNQ2/3 Channels and Activation of TRPC Channels in Multimodal Control of Excitability in Dentate Gyrus Granule Cells. J Neurosci 2018; 39:1566-1587. [PMID: 30593498 DOI: 10.1523/jneurosci.1781-18.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 12/17/2018] [Accepted: 12/20/2018] [Indexed: 12/21/2022] Open
Abstract
KCNQ (Kv7, "M-type") K+ channels and TRPC (transient receptor potential, "canonical") cation channels are coupled to neuronal discharge properties and are regulated via Gq/11-protein-mediated signals. Stimulation of Gq/11-coupled receptors both consumes phosphatidylinositol 4,5-bisphosphate (PIP2) via phosphalipase Cβ hydrolysis and stimulates PIP2 synthesis via rises in Ca2+ i and other signals. Using brain-slice electrophysiology and Ca2+ imaging from male and female mice, we characterized threshold K+ currents in dentate gyrus granule cells (DGGCs) and CA1 pyramidal cells, the effects of Gq/11-coupled muscarinic M1 acetylcholine (M1R) stimulation on M current and on neuronal discharge properties, and elucidated the intracellular signaling mechanisms involved. We observed disparate signaling cascades between DGGCs and CA1 neurons. DGGCs displayed M1R enhancement of M-current, rather than suppression, due to stimulation of PIP2 synthesis, which was paralleled by increased PIP2-gated G-protein coupled inwardly rectifying K+ currents as well. Deficiency of KCNQ2-containing M-channels ablated the M1R-induced enhancement of M-current in DGGCs. Simultaneously, M1R stimulation in DGGCs induced robust increases in [Ca2+]i, mostly due to TRPC currents, consistent with, and contributing to, neuronal depolarization and hyperexcitability. CA1 neurons did not display such multimodal signaling, but rather M current was suppressed by M1R stimulation in these cells, similar to the previously described actions of M1R stimulation on M-current in peripheral ganglia that mostly involves PIP2 depletion. Therefore, these results point to a pleiotropic network of cholinergic signals that direct cell-type-specific, precise control of hippocampal function with strong implications for hyperexcitability and epilepsy.SIGNIFICANCE STATEMENT At the neuronal membrane, protein signaling cascades consisting of ion channels and metabotropic receptors govern the electrical properties and neurotransmission of neuronal networks. Muscarinic acetylcholine receptors are G-protein-coupled metabotropic receptors that control the excitability of neurons through regulating ion channels, intracellular Ca2+ signals, and other second-messenger cascades. We have illuminated previously unknown actions of muscarinic stimulation on the excitability of hippocampal principal neurons that include M channels, TRPC (transient receptor potential, "canonical") cation channels, and powerful regulation of lipid metabolism. Our results show that these signaling pathways, and mechanisms of excitability, are starkly distinct between peripheral ganglia and brain, and even between different principal neurons in the hippocampus.
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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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23
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Nguyen RL, Medvedeva YV, Ayyagari TE, Schmunk G, Gargus JJ. Intracellular calcium dysregulation in autism spectrum disorder: An analysis of converging organelle signaling pathways. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1865:1718-1732. [PMID: 30992134 DOI: 10.1016/j.bbamcr.2018.08.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 07/18/2018] [Accepted: 08/02/2018] [Indexed: 12/14/2022]
Abstract
Autism spectrum disorder (ASD) is a group of complex, neurological disorders that affect early cognitive, social, and verbal development. Our understanding of ASD has vastly improved with advances in genomic sequencing technology and genetic models that have identified >800 loci with variants that increase susceptibility to ASD. Although these findings have confirmed its high heritability, the underlying mechanisms by which these genes produce the ASD phenotypes have not been defined. Current efforts have begun to "functionalize" many of these variants and envisage how these susceptibility factors converge at key biochemical and biophysical pathways. In this review, we discuss recent work on intracellular calcium signaling in ASD, including our own work, which begins to suggest it as a compelling candidate mechanism in the pathophysiology of autism and a potential therapeutic target. We consider how known variants in the calcium signaling genomic architecture of ASD may exert their deleterious effects along pathways particularly involving organelle dysfunction including the endoplasmic reticulum (ER), a major calcium store, and the mitochondria, a major calcium ion buffer, and theorize how many of these pathways intersect.
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Affiliation(s)
- Rachel L Nguyen
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA; UCI Center for Autism Research and Translation, School of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Yuliya V Medvedeva
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA; UCI Center for Autism Research and Translation, School of Medicine, University of California, Irvine, Irvine, CA, USA; Department of Neurology, University of California, Irvine, Irvine, CA, USA
| | - Tejasvi E Ayyagari
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA; UCI Center for Autism Research and Translation, School of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Galina Schmunk
- UCI Center for Autism Research and Translation, School of Medicine, University of California, Irvine, Irvine, CA, USA
| | - John Jay Gargus
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA; UCI Center for Autism Research and Translation, School of Medicine, University of California, Irvine, Irvine, CA, USA; Department of Pediatrics, Section of Human Genetics and Genomics, University of California, Irvine, Irvine, CA, USA.
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24
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Kano M, Watanabe T, Uesaka N, Watanabe M. Multiple Phases of Climbing Fiber Synapse Elimination in the Developing Cerebellum. THE CEREBELLUM 2018; 17:722-734. [DOI: 10.1007/s12311-018-0964-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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25
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Thompson JM, Yakhnitsa V, Ji G, Neugebauer V. Small conductance calcium activated potassium (SK) channel dependent and independent effects of riluzole on neuropathic pain-related amygdala activity and behaviors in rats. Neuropharmacology 2018; 138:219-231. [PMID: 29908238 DOI: 10.1016/j.neuropharm.2018.06.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 05/04/2018] [Accepted: 06/11/2018] [Indexed: 01/17/2023]
Abstract
BACKGROUND AND PURPOSE Chronic neuropathic pain is an important healthcare issue with significant emotional components. The amygdala is a brain region involved in pain and emotional-affective states and disorders. The central amygdala output nucleus (CeA) contains small-conductance calcium-activated potassium (SK) channels that can control neuronal activity. A clinically available therapeutic, riluzole can activate SK channels and may have antinociceptive effects through a supraspinal action. We tested the hypothesis that riluzole inhibits neuropathic pain behaviors by inhibiting pain-related changes in CeA neurons, in part at least through SK channel activation. EXPERIMENTAL APPROACH Brain slice physiology and behavioral assays were done in adult Sprague Dawley rats. Audible and ultrasonic vocalizations and von Frey thresholds were measured in sham and neuropathic rats 4 weeks after left L5 spinal nerve ligation (SNL model). Whole cell patch-clamp recordings of regular firing CeA neurons in brain slices were used to measure synaptic transmission and neuronal excitability. KEY RESULTS In brain slices, riluzole increased the SK channel-mediated afterhyperpolarization and synaptic inhibition, but inhibited neuronal excitability through an SK channel independent action. SNL rats had increased vocalizations and decreased withdrawal thresholds compared to sham rats, and intra-CeA administration of riluzole inhibited vocalizations and depression-like behaviors but did not affect withdrawal thresholds. Systemic riluzole administration also inhibited these changes, demonstrating the clinical utility of this strategy. SK channel blockade in the CeA attenuated the inhibitory effects of systemic riluzole on vocalizations, confirming SK channel involvement in these effects. CONCLUSIONS AND IMPLICATIONS The results suggest that riluzole has beneficial effects on neuropathic pain behaviors through SK channel dependent and independent mechanisms in the amygdala.
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Affiliation(s)
- Jeremy M Thompson
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX, USA
| | - Vadim Yakhnitsa
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX, USA
| | - Guangchen Ji
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX, USA
| | - Volker Neugebauer
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX, USA; Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
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26
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Hoxha E, Balbo I, Miniaci MC, Tempia F. Purkinje Cell Signaling Deficits in Animal Models of Ataxia. Front Synaptic Neurosci 2018; 10:6. [PMID: 29760657 PMCID: PMC5937225 DOI: 10.3389/fnsyn.2018.00006] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Accepted: 04/09/2018] [Indexed: 12/19/2022] Open
Abstract
Purkinje cell (PC) dysfunction or degeneration is the most frequent finding in animal models with ataxic symptoms. Mutations affecting intrinsic membrane properties can lead to ataxia by altering the firing rate of PCs or their firing pattern. However, the relationship between specific firing alterations and motor symptoms is not yet clear, and in some cases PC dysfunction precedes the onset of ataxic signs. Moreover, a great variety of ionic and synaptic mechanisms can affect PC signaling, resulting in different features of motor dysfunction. Mutations affecting Na+ channels (NaV1.1, NaV1.6, NaVβ4, Fgf14 or Rer1) reduce the firing rate of PCs, mainly via an impairment of the Na+ resurgent current. Mutations that reduce Kv3 currents limit the firing rate frequency range. Mutations of Kv1 channels act mainly on inhibitory interneurons, generating excessive GABAergic signaling onto PCs, resulting in episodic ataxia. Kv4.3 mutations are responsible for a complex syndrome with several neurologic dysfunctions including ataxia. Mutations of either Cav or BK channels have similar consequences, consisting in a disruption of the firing pattern of PCs, with loss of precision, leading to ataxia. Another category of pathogenic mechanisms of ataxia regards alterations of synaptic signals arriving at the PC. At the parallel fiber (PF)-PC synapse, mutations of glutamate delta-2 (GluD2) or its ligand Crbl1 are responsible for the loss of synaptic contacts, abolishment of long-term depression (LTD) and motor deficits. At the same synapse, a correct function of metabotropic glutamate receptor 1 (mGlu1) receptors is necessary to avoid ataxia. Failure of climbing fiber (CF) maturation and establishment of PC mono-innervation occurs in a great number of mutant mice, including mGlu1 and its transduction pathway, GluD2, semaphorins and their receptors. All these models have in common the alteration of PC output signals, due to a variety of mechanisms affecting incoming synaptic signals or the way they are processed by the repertoire of ionic channels responsible for intrinsic membrane properties. Although the PC is a final common pathway of ataxia, the link between specific firing alterations and neurologic symptoms has not yet been systematically studied and the alterations of the cerebellar contribution to motor signals are still unknown.
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Affiliation(s)
- Eriola Hoxha
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Turin, Italy.,Department of Neuroscience, University of Torino, Turin, Italy
| | - Ilaria Balbo
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Turin, Italy.,Department of Neuroscience, University of Torino, Turin, Italy
| | - Maria Concetta Miniaci
- Department of Pharmacy, School of Medicine, University of Naples Federico II, Naples, Italy
| | - Filippo Tempia
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Turin, Italy.,Department of Neuroscience, University of Torino, Turin, Italy.,National Institute of Neuroscience (INN), Turin, Italy
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27
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Hirabayashi Y, Kwon SK, Paek H, Pernice WM, Paul MA, Lee J, Erfani P, Raczkowski A, Petrey DS, Pon LA, Polleux F. ER-mitochondria tethering by PDZD8 regulates Ca 2+ dynamics in mammalian neurons. Science 2018; 358:623-630. [PMID: 29097544 DOI: 10.1126/science.aan6009] [Citation(s) in RCA: 291] [Impact Index Per Article: 48.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 08/21/2017] [Accepted: 09/20/2017] [Indexed: 01/06/2023]
Abstract
Interfaces between organelles are emerging as critical platforms for many biological responses in eukaryotic cells. In yeast, the ERMES complex is an endoplasmic reticulum (ER)-mitochondria tether composed of four proteins, three of which contain a SMP (synaptotagmin-like mitochondrial-lipid binding protein) domain. No functional ortholog for any ERMES protein has been identified in metazoans. Here, we identified PDZD8 as an ER protein present at ER-mitochondria contacts. The SMP domain of PDZD8 is functionally orthologous to the SMP domain found in yeast Mmm1. PDZD8 was necessary for the formation of ER-mitochondria contacts in mammalian cells. In neurons, PDZD8 was required for calcium ion (Ca2+) uptake by mitochondria after synaptically induced Ca2+-release from ER and thereby regulated cytoplasmic Ca2+ dynamics. Thus, PDZD8 represents a critical ER-mitochondria tethering protein in metazoans. We suggest that ER-mitochondria coupling is involved in the regulation of dendritic Ca2+ dynamics in mammalian neurons.
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Affiliation(s)
- Yusuke Hirabayashi
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA.,Japan Science and Technology Agency (JST), Precursory Research for Embryonic Science and Technology (PRESTO), Tokyo, Japan
| | - Seok-Kyu Kwon
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Hunki Paek
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Wolfgang M Pernice
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Maëla A Paul
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Jinoh Lee
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Parsa Erfani
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Ashleigh Raczkowski
- Simons Electron Microscopy Center, New York Structural Biology Center (NYSBC), New York, NY 10027, USA
| | - Donald S Petrey
- Center for Computational Biology and Bioinformatics, Department of Systems Biology, Columbia University, New York, NY 10032, USA.,Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA
| | - Liza A Pon
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA.,Institute of Human Nutrition, Columbia University, New York, NY 10032, USA
| | - Franck Polleux
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA. .,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
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28
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Grossberg S, Kishnan D. Neural Dynamics of Autistic Repetitive Behaviors and Fragile X Syndrome: Basal Ganglia Movement Gating and mGluR-Modulated Adaptively Timed Learning. Front Psychol 2018; 9:269. [PMID: 29593596 PMCID: PMC5859312 DOI: 10.3389/fpsyg.2018.00269] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 02/19/2018] [Indexed: 11/13/2022] Open
Abstract
This article develops the iSTART neural model that proposes how specific imbalances in cognitive, emotional, timing, and motor processes that involve brain regions like prefrontal cortex, temporal cortex, amygdala, hypothalamus, hippocampus, and cerebellum may interact together to cause behavioral symptoms of autism. These imbalances include underaroused emotional depression in the amygdala/hypothalamus, learning of hyperspecific recognition categories that help to cause narrowly focused attention in temporal and prefrontal cortices, and breakdowns of adaptively timed motivated attention and motor circuits in the hippocampus and cerebellum. The article expands the model's explanatory range by, first, explaining recent data about Fragile X syndrome (FXS), mGluR, and trace conditioning; and, second, by explaining distinct causes of stereotyped behaviors in individuals with autism. Some of these stereotyped behaviors, such as an insistence on sameness and circumscribed interests, may result from imbalances in the cognitive and emotional circuits that iSTART models. These behaviors may be ameliorated by operant conditioning methods. Other stereotyped behaviors, such as repetitive motor behaviors, may result from imbalances in how the direct and indirect pathways of the basal ganglia open or close movement gates, respectively. These repetitive behaviors may be ameliorated by drugs that augment D2 dopamine receptor responses or reduce D1 dopamine receptor responses. The article also notes the ubiquitous role of gating by basal ganglia loops in regulating all the functions that iSTART models.
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Affiliation(s)
- Stephen Grossberg
- Center for Adaptive Systems, Graduate Program in Cognitive and Neural Systems, Departments of Mathematics & Statistics, Psychological & Brain Sciences, and Biomedical Engineering, Boston University, Boston, MA, United States
| | - Devika Kishnan
- Department of Biomedical Engineering, Boston University, Boston, MA, United States
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29
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Kucharz K, Lauritzen M. CaMKII-dependent endoplasmic reticulum fission by whisker stimulation and during cortical spreading depolarization. Brain 2018. [DOI: 10.1093/brain/awy036] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Affiliation(s)
- Krzysztof Kucharz
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Maersk Tower, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Martin Lauritzen
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Maersk Tower, Blegdamsvej 3, 2200 Copenhagen N, Denmark
- Department of Clinical Neurophysiology, Rigshospitalet, Nordre Ringvej 57, 2600 Glostrup, Denmark
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30
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Zylbertal A, Yarom Y, Wagner S. The Slow Dynamics of Intracellular Sodium Concentration Increase the Time Window of Neuronal Integration: A Simulation Study. Front Comput Neurosci 2017; 11:85. [PMID: 28970791 PMCID: PMC5609115 DOI: 10.3389/fncom.2017.00085] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 09/04/2017] [Indexed: 12/02/2022] Open
Abstract
Changes in intracellular Na+ concentration ([Na+]i) are rarely taken into account when neuronal activity is examined. As opposed to Ca2+, [Na+]i dynamics are strongly affected by longitudinal diffusion, and therefore they are governed by the morphological structure of the neurons, in addition to the localization of influx and efflux mechanisms. Here, we examined [Na+]i dynamics and their effects on neuronal computation in three multi-compartmental neuronal models, representing three distinct cell types: accessory olfactory bulb (AOB) mitral cells, cortical layer V pyramidal cells, and cerebellar Purkinje cells. We added [Na+]i as a state variable to these models, and allowed it to modulate the Na+ Nernst potential, the Na+-K+ pump current, and the Na+-Ca2+ exchanger rate. Our results indicate that in most cases [Na+]i dynamics are significantly slower than [Ca2+]i dynamics, and thus may exert a prolonged influence on neuronal computation in a neuronal type specific manner. We show that [Na+]i dynamics affect neuronal activity via three main processes: reduction of EPSP amplitude in repeatedly active synapses due to reduction of the Na+ Nernst potential; activity-dependent hyperpolarization due to increased activity of the Na+-K+ pump; specific tagging of active synapses by extended Ca2+ elevation, intensified by concurrent back-propagating action potentials or complex spikes. Thus, we conclude that [Na+]i dynamics should be considered whenever synaptic plasticity, extensive synaptic input, or bursting activity are examined.
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Affiliation(s)
- Asaph Zylbertal
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University and the Edmond and Lily Safra Center for Brain SciencesJerusalem, Israel
| | - Yosef Yarom
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University and the Edmond and Lily Safra Center for Brain SciencesJerusalem, Israel
| | - Shlomo Wagner
- Sagol Department of Neurobiology, University of HaifaHaifa, Israel
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31
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Choo M, Miyazaki T, Yamazaki M, Kawamura M, Nakazawa T, Zhang J, Tanimura A, Uesaka N, Watanabe M, Sakimura K, Kano M. Retrograde BDNF to TrkB signaling promotes synapse elimination in the developing cerebellum. Nat Commun 2017; 8:195. [PMID: 28775326 PMCID: PMC5543168 DOI: 10.1038/s41467-017-00260-w] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 06/14/2017] [Indexed: 12/31/2022] Open
Abstract
Elimination of early-formed redundant synapses during postnatal development is essential for functional neural circuit formation. Purkinje cells (PCs) in the neonatal cerebellum are innervated by multiple climbing fibers (CFs). A single CF is strengthened whereas the other CFs are eliminated in each PC dependent on postsynaptic activity in PC, but the underlying mechanisms are largely unknown. Here, we report that brain-derived neurotrophic factor (BDNF) from PC facilitates CF synapse elimination. By PC-specific deletion of BDNF combined with knockdown of BDNF receptors in CF, we show that BDNF acts retrogradely on TrkB in CFs, and facilitates elimination of CF synapses from PC somata during the third postnatal week. We also show that BDNF shares signaling pathway with metabotropic glutamate receptor 1, a key molecule that triggers a canonical pathway for CF synapse elimination. These results indicate that unlike other synapses, BDNF mediates punishment signal for synapse elimination in the developing cerebellum. During development, synapses are selectively strengthened or eliminated by activity-dependent competition. Here, the authors show that BDNF-TrkB retrograde signaling is a “punishment” signal that leads to elimination of climbing fiber-onto-Purkinje cell synapses in the developing cerebellum.
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Affiliation(s)
- Myeongjeong Choo
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Taisuke Miyazaki
- Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo, 060-8638, Japan
| | - Maya Yamazaki
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan
| | - Meiko Kawamura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan
| | - Takanobu Nakazawa
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Jianling Zhang
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Asami Tanimura
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Naofumi Uesaka
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo, 060-8638, Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan.
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32
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GluD2 Endows Parallel Fiber-Purkinje Cell Synapses with a High Regenerative Capacity. J Neurosci 2017; 36:4846-58. [PMID: 27122040 DOI: 10.1523/jneurosci.0161-16.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 03/22/2016] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED Although injured axons usually do not regenerate in the adult CNS, parallel fibers (PFs) regenerate synaptic connections onto cerebellar Purkinje cells (PCs). In this study, we investigated the role of GluD2 in this regenerative process after PF transection using GluD2-knock-out (KO) mice. All dendritic spines on distal dendrites were innervated by PFs in sham-operated wild-type controls, whereas one-third were devoid of innervation in GluD2-KO mice. In both genotypes, a steep drop in the number of PF synapses occurred with a reciprocal surge in the number of free spines on postlesion day 1, when the PF territory aberrantly expanded toward the proximal dendrites. In wild-type mice, the territory and number of PF synapses were nearly fully restored to normal on postlesion day 7, although PF density remained low. Moreover, presynaptic and postsynaptic elements were markedly enlarged, and the PF terminal-to-PC spine contact ratio increased from 1:1 to 1:2 at most synapses. On postlesion day 30, the size and contact ratio of PF synapses returned to sham-operated control values and PF density recovered through the sprouting and elongation of PF collaterals. However, GluD2-KO mice showed neither a hypertrophic response nor territorial restoration 7 d postlesion, nor the recovery of PF axons or synapses on postlesion day 30. This suggests that PF wiring regenerates initially by inducing hypertrophic responses in surviving synaptic elements (hypertrophic phase), followed by collateral formation by PF axons and retraction of PF synapses (remodeling phase). Without GluD2, no transition to these regenerative phases occurs. SIGNIFICANCE STATEMENT The glutamate receptor GluD2 expressed at parallel fiber (PF)-Purkinje cell (PC) synapses regulates the formation and maintenance of the synapses. To investigate the role of GluD2 in their extraordinarily high regenerative capacity, the process after surgical transection of PFs was compared between wild-type and GluD2-knock-out mice. We discovered that, in wild-type mice, PF synapses regenerate initially by inducing hypertrophic responses in surviving synaptic elements, and then by sprouting and elongation of PF collaterals. Subsequently, hypertrophied PF synapses remodel into compact synapses. In GluD2-knock-out mice, PF wiring remains in the degenerative phase, showing neither a hypertrophic response nor recovery of PF axons or synapses. Our finding thus highlights that synaptic connection in the adult brain can regenerate with aid of GluD2.
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33
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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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34
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Kano M, Watanabe T. Type-1 metabotropic glutamate receptor signaling in cerebellar Purkinje cells in health and disease. F1000Res 2017; 6:416. [PMID: 28435670 PMCID: PMC5381626 DOI: 10.12688/f1000research.10485.1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/30/2017] [Indexed: 01/28/2023] Open
Abstract
The cerebellum is a brain structure involved in coordination, control, and learning of movements, as well as certain aspects of cognitive function. Purkinje cells are the sole output neurons from the cerebellar cortex and therefore play crucial roles in the overall function of the cerebellum. The type-1 metabotropic glutamate receptor (mGluR1) is a key “hub” molecule that is critically involved in the regulation of synaptic wiring, excitability, synaptic response, and synaptic plasticity of Purkinje cells. In this review, we aim to highlight how mGluR1 controls these events in Purkinje cells. We also describe emerging evidence that altered mGluR1 signaling in Purkinje cells underlies cerebellar dysfunctions in several clinically relevant mouse models of human ataxias.
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Affiliation(s)
- Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Takaki Watanabe
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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35
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Hisatsune C, Mikoshiba K. IP 3 receptor mutations and brain diseases in human and rodents. J Neurochem 2017; 141:790-807. [PMID: 28211945 DOI: 10.1111/jnc.13991] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 02/03/2017] [Accepted: 02/12/2017] [Indexed: 01/15/2023]
Abstract
The inositol 1,4,5-trisphosphate receptor (IP3 R) is a huge Ca2+ channel that is localized at the endoplasmic reticulum. The IP3 R releases Ca2+ from the endoplasmic reticulum upon binding to IP3 , which is produced by various extracellular stimuli through phospholipase C activation. All vertebrate organisms have three subtypes of IP3 R genes, which have distinct properties of IP3 -binding and Ca2+ sensitivity, and are differently regulated by phosphorylation and by their associated proteins. Each cell type expresses the three subtypes of IP3 R in a distinct proportion, which is important for creating and maintaining spatially and temporally appropriate intracellular Ca2+ level patterns for the regulation of specific physiological phenomena. Of the three types of IP3 Rs, the type 1 receptor (IP3 R1) is dominantly expressed in the brain and is important for brain function. Recent emerging evidence suggests that abnormal Ca2+ signals from the IP3 R1 are closely associated with human brain pathology. In this review, we focus on the recent advances in our knowledge of the regulation of IP3 R1 and its functional implication in human brain diseases, as revealed by IP3 R mutation studies and analysis of human disease-associated genes. This article is part of the mini review series "60th Anniversary of the Japanese Society for Neurochemistry".
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Affiliation(s)
- Chihiro Hisatsune
- Laboratory for Developmental Neurobiology, Brain Science Institute, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, Brain Science Institute, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan
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36
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Ly R, Bouvier G, Szapiro G, Prosser HM, Randall AD, Kano M, Sakimura K, Isope P, Barbour B, Feltz A. Contribution of postsynaptic T-type calcium channels to parallel fibre-Purkinje cell synaptic responses. J Physiol 2016; 594:915-36. [PMID: 26627919 DOI: 10.1113/jp271623] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 12/01/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS At the parallel fibre-Purkinje cell glutamatergic synapse, little or no Ca(2+) entry takes place through postsynaptic neurotransmitter receptors, although postsynaptic calcium increases are clearly involved in the synaptic plasticity. Postsynaptic voltage-gated Ca(2+) channels therefore constitute the sole rapid postsynaptic Ca(2+) signalling mechanism, making it essential to understand how they contribute to the synaptic signalling. Using a selective T-type calcium channel antagonist, we describe a T-type component of the EPSC that is activated by the AMPA receptor-mediated depolarization of the spine and thus will contribute to the local calcium dynamics. This component can amount up to 20% of the EPSC, and this fraction is maintained even at the high frequencies sometimes encountered in sensory processing. Modelling based on our biophysical characterization of T-type calcium channels in Purkinje cells suggests that the brief spine EPSCs cause the activated T-type channels to deactivate rather than inactivate, enabling repetitive activation. ABSTRACT In the cerebellum, sensory information is conveyed to Purkinje cells (PC) via the granule cell/parallel fibre (PF) pathway. Plasticity at the PF-PC synapse is considered to be a mechanism of information storage in motor learning. The induction of synaptic plasticity in the cerebellum and elsewhere usually involves intracellular Ca(2+) signals. Unusually, postsynaptic Ca(2+) signalling in PF-PC spines does not involve ionotropic glutamatergic receptors because postsynaptic NMDA receptors are absent and the AMPA receptors are Ca(2+) -impermeable; postsynaptic voltage-gated Ca(2+) channels therefore constitute the sole rapid Ca(2+) signalling mechanism. Low-threshold activated T-type calcium channels are present at the synapse, although their contribution to PF-PC synaptic responses is unknown. Taking advantage of 3,5-dichloro-N-[1-(2,2-dimethyl-tetrahydro-pyran-4-ylmethyl)-4-fluoro-piperidin-4-ylmethyl]-benzamide, a selective T-type channel antagonist, we show in the mouse that inhibition of these channels reduces PF-PC excitatory postsynaptic currents and excitatory postsynaptic potentials by 15-20%. This contribution was preserved during sparse input and repetitive activity. We characterized the biophysical properties of native T-type channels in young animals and modelled their activation during simulated dendritic excitatory postsynaptic potential waveforms. The comparison of modelled and observed synaptic responses suggests that T-type channels only activate in spines that are strongly depolarized by their synaptic input, a process requiring a high spine neck resistance. This brief and local activation ensures that T-type channels rapidly deactivate, thereby limiting inactivation during repetitive synaptic activity. T-type channels are therefore ideally situated to provide synaptic Ca(2+) entry at PF-PC spines.
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Affiliation(s)
- Romain Ly
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
| | - Guy Bouvier
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
| | - German Szapiro
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
| | - Haydn M Prosser
- GlaxoSmithKline Pharmaceuticals, New Frontiers Science Park, Third Avenue, Harlow, UK., Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
| | - Andrew D Randall
- GlaxoSmithKline Pharmaceuticals, New Frontiers Science Park, Third Avenue, Harlow, UK.,School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol, UK
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Philippe Isope
- INCI, CNRS UPR 3212, Centre de Neurochimie, Strasbourg, France
| | - Boris Barbour
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
| | - Anne Feltz
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
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37
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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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Kwon SK, Hirabayashi Y, Polleux F. Organelle-Specific Sensors for Monitoring Ca 2+ Dynamics in Neurons. Front Synaptic Neurosci 2016; 8:29. [PMID: 27695411 PMCID: PMC5025517 DOI: 10.3389/fnsyn.2016.00029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 08/30/2016] [Indexed: 11/16/2022] Open
Abstract
Calcium (Ca2+) plays innumerable critical functions in neurons ranging from regulation of neurotransmitter release and synaptic plasticity to activity-dependent transcription. Therefore, more than any other cell types, neurons are critically dependent on spatially and temporally controlled Ca2+ dynamics. This is achieved through an exquisite level of compartmentalization of Ca2+ storage and release from various organelles. The function of these organelles in the regulation of Ca2+ dynamics has been studied for decades using electrophysiological and optical methods combined with pharmacological and genetic alterations. Mitochondria and the endoplasmic reticulum (ER) are among the organelles playing the most critical roles in Ca2+ dynamics in neurons. At presynaptic boutons, Ca2+ triggers neurotransmitter release and synaptic plasticity, and postsynaptically, Ca2+ mobilization mediates long-term synaptic plasticity. To explore Ca2+ dynamics in live cells and intact animals, various synthetic and genetically encoded fluorescent Ca2+ sensors were developed, and recently, many groups actively increased the sensitivity and diversity of genetically encoded Ca2+ indicators (GECIs). Following conjugation with various signal peptides, these improved GECIs can be targeted to specific subcellular compartments, allowing monitoring of organelle-specific Ca2+ dynamics. Here, we review recent findings unraveling novel roles for mitochondria- and ER-dependent Ca2+ dynamics in neurons and at synapses.
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Affiliation(s)
- Seok-Kyu Kwon
- Department of Neuroscience, Mortimer B. Zuckerman Mind Brain Behavior Institute, Kavli Institute for Brain Science, Columbia University Medical Center New York, NY, USA
| | - Yusuke Hirabayashi
- Department of Neuroscience, Mortimer B. Zuckerman Mind Brain Behavior Institute, Kavli Institute for Brain Science, Columbia University Medical Center New York, NY, USA
| | - Franck Polleux
- Department of Neuroscience, Mortimer B. Zuckerman Mind Brain Behavior Institute, Kavli Institute for Brain Science, Columbia University Medical Center New York, NY, USA
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39
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Shuvaev AN, Hosoi N, Sato Y, Yanagihara D, Hirai H. Progressive impairment of cerebellar mGluR signalling and its therapeutic potential for cerebellar ataxia in spinocerebellar ataxia type 1 model mice. J Physiol 2016; 595:141-164. [PMID: 27440721 DOI: 10.1113/jp272950] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 07/11/2016] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS Spinocerebellar ataxia type 1 (SCA1) is a progressive neurodegenerative disease caused by a gene defect, leading to movement disorder such as cerebellar ataxia. It remains largely unknown which functional defect contributes to the cerebellar ataxic phenotype in SCA1. In this study, we report progressive dysfunction of metabotropic glutamate receptor (mGluR) signalling, which leads to smaller slow synaptic responses, reduced dendritic Ca2+ signals and impaired synaptic plasticity at cerebellar synapses, in the early disease stage of SCA1 model mice. We also show that enhancement of mGluR signalling by a clinically available drug, baclofen, leads to improvement of motor performance in SCA1 mice. SCA1 is an incurable disease with no effective treatment, and our results may provide mechanistic grounds for targeting mGluRs and a novel drug therapy with baclofen to treat SCA1 patients in the future. ABSTRACT Spinocerebellar ataxia type 1 (SCA1) is a progressive neurodegenerative disease that presents with cerebellar ataxia and motor learning defects. Previous studies have indicated that the pathology of SCA1, as well as other ataxic diseases, is related to signalling pathways mediated by the metabotropic glutamate receptor type 1 (mGluR1), which is indispensable for proper motor coordination and learning. However, the functional contribution of mGluR signalling to SCA1 pathology is unclear. In the present study, we show that SCA1 model mice develop a functional impairment of mGluR signalling which mediates slow synaptic responses, dendritic Ca2+ signals, and short- and long-term synaptic plasticity at parallel fibre (PF)-Purkinje cell (PC) synapses in a progressive manner from the early disease stage (5 postnatal weeks) prior to PC death. Notably, impairment of mGluR-mediated dendritic Ca2+ signals linearly correlated with a reduction of PC capacitance (cell surface area) in disease progression. Enhancement of mGluR signalling by baclofen, a clinically available GABAB receptor agonist, led to an improvement of motor performance in SCA1 mice and the improvement lasted ∼1 week after a single application of baclofen. Moreover, the restoration of motor performance in baclofen-treated SCA1 mice matched the functional recovery of mGluR-mediated slow synaptic currents and mGluR-dependent short- and long-term synaptic plasticity. These results suggest that impairment of synaptic mGluR cascades is one of the important contributing factors to cerebellar ataxia in early and middle stages of SCA1 pathology, and that modulation of mGluR signalling by baclofen or other clinical interventions may be therapeutic targets to treat SCA1.
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Affiliation(s)
- Anton N Shuvaev
- Department of Neurophysiology and Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma, 371-8511, Japan.,Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V. F. Voino-Yasenetsky, Krasnoyarsk, 660022, Russia
| | - Nobutake Hosoi
- Department of Neurophysiology and Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma, 371-8511, Japan
| | - Yamato Sato
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo, 153-8902, Japan
| | - Dai Yanagihara
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo, 153-8902, Japan
| | - Hirokazu Hirai
- Department of Neurophysiology and Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma, 371-8511, Japan.,Research Program for Neural Signalling, Division of Endocrinology, Metabolism and Signal Research, Gunma University Initiative for Advanced Research, Maebashi, Gunma, 371-8511, Japan
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40
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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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41
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Visualization of Ca2+ Filling Mechanisms upon Synaptic Inputs in the Endoplasmic Reticulum of Cerebellar Purkinje Cells. J Neurosci 2016; 35:15837-46. [PMID: 26631466 DOI: 10.1523/jneurosci.3487-15.2015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The endoplasmic reticulum (ER) plays crucial roles in intracellular Ca(2+) signaling, serving as both a source and sink of Ca(2+), and regulating a variety of physiological and pathophysiological events in neurons in the brain. However, spatiotemporal Ca(2+) dynamics within the ER in central neurons remain to be characterized. In this study, we visualized synaptic activity-dependent ER Ca(2+) dynamics in mouse cerebellar Purkinje cells (PCs) using an ER-targeted genetically encoded Ca(2+) indicator, G-CEPIA1er. We used brief parallel fiber stimulation to induce a local decrease in the ER luminal Ca(2+) concentration ([Ca(2+)]ER) in dendrites and spines. In this experimental system, the recovery of [Ca(2+)]ER takes several seconds, and recovery half-time depends on the extent of ER Ca(2+) depletion. By combining imaging analysis and numerical simulation, we show that the intraluminal diffusion of Ca(2+), rather than Ca(2+) reuptake, is the dominant mechanism for the replenishment of the local [Ca(2+)]ER depletion immediately following the stimulation. In spines, the ER filled almost simultaneously with parent dendrites, suggesting that the ER within the spine neck does not represent a significant barrier to Ca(2+) diffusion. Furthermore, we found that repetitive climbing fiber stimulation, which induces cytosolic Ca(2+) spikes in PCs, cumulatively increased [Ca(2+)]ER. These results indicate that the neuronal ER functions both as an intracellular tunnel to redistribute stored Ca(2+) within the neurons, and as a leaky integrator of Ca(2+) spike-inducing synaptic inputs.
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42
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Power EM, English NA, Empson RM. Are Type 1 metabotropic glutamate receptors a viable therapeutic target for the treatment of cerebellar ataxia? J Physiol 2016; 594:4643-52. [PMID: 26748626 DOI: 10.1113/jp271153] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 12/19/2015] [Indexed: 12/13/2022] Open
Abstract
The cerebellum is a key brain structure for accurate coordination of sensory and motor function. Compared with other brain regions, the cerebellum expresses a particularly high level of Type 1 metabotropic glutamate receptors (mGluR1). In this review we aim to explore the significance of these receptors for cerebellar synapse function and their potential for treating cerebellar ataxia, a poorly treated degenerative motor disorder that is often hereditary. We find a significant and historical literature showing pivotal mechanisms linking mGluR1 activity with healthy cerebellar synaptic function and motor coordination. This is best illustrated by the impaired motor behaviour in mGluR1 knockout mice that bears strong resemblance to human ataxias. More recent literature also indicates that an imbalance of mGluR1 signalling is as critical as its removal. Too much, as well as too little, mGluR1 activity contributes to ataxia in several clinically relevant mouse models, and perhaps also in humans. Given the availability and ongoing refinement of selective pharmacological tools to either reduce (negative allosteric modulation) or boost (positive allosteric modulation) mGluR1 activity, our findings suggest that pharmacological manipulation of these receptors should be explored as an exciting new approach for the treatment of a variety of human cerebellar ataxias.
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Affiliation(s)
- Emmet M Power
- Department of Physiology, Brain Research New Zealand, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand, 9054
| | - Natalya A English
- Department of Physiology, Brain Research New Zealand, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand, 9054
| | - Ruth M Empson
- Department of Physiology, Brain Research New Zealand, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand, 9054
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43
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Territories of heterologous inputs onto Purkinje cell dendrites are segregated by mGluR1-dependent parallel fiber synapse elimination. Proc Natl Acad Sci U S A 2016; 113:2282-7. [PMID: 26858447 DOI: 10.1073/pnas.1511513113] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
In Purkinje cells (PCs) of the cerebellum, a single "winner" climbing fiber (CF) monopolizes proximal dendrites, whereas hundreds of thousands of parallel fibers (PFs) innervate distal dendrites, and both CF and PF inputs innervate a narrow intermediate domain. It is unclear how this segregated CF and PF innervation is established on PC dendrites. Through reconstruction of dendritic innervation by serial electron microscopy, we show that from postnatal day 9-15 in mice, both CF and PF innervation territories vigorously expand because of an enlargement of the region of overlapping innervation. From postnatal day 15 onwards, segregation of these territories occurs with robust shortening of the overlapping proximal region. Thus, innervation territories by the heterologous inputs are refined during the early postnatal period. Intriguingly, this transition is arrested in mutant mice lacking the type 1 metabotropic glutamate receptor (mGluR1) or protein kinase Cγ (PKCγ), resulting in the persistence of an abnormally expanded overlapping region. This arrested territory refinement is rescued by lentivirus-mediated expression of mGluR1α into mGluR1-deficient PCs. At the proximal dendrite of rescued PCs, PF synapses are eliminated and free spines emerge instead, whereas the number and density of CF synapses are unchanged. Because the mGluR1-PKCγ signaling pathway is also essential for the late-phase of CF synapse elimination, this signaling pathway promotes the two key features of excitatory synaptic wiring in PCs, namely CF monoinnervation by eliminating redundant CF synapses from the soma, and segregated territories of CF and PF innervation by eliminating competing PF synapses from proximal dendrites.
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44
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Smeets CJLM, Verbeek DS. Climbing fibers in spinocerebellar ataxia: A mechanism for the loss of motor control. Neurobiol Dis 2016; 88:96-106. [PMID: 26792399 DOI: 10.1016/j.nbd.2016.01.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 11/19/2015] [Accepted: 01/09/2016] [Indexed: 11/26/2022] Open
Abstract
The spinocerebellar ataxias (SCAs) form an ever-growing group of neurodegenerative disorders causing dysfunction of the cerebellum and loss of motor control in patients. Currently, 41 different genetic causes have been identified, with each mutation affecting a different gene. Interestingly, these diverse genetic causes all disrupt cerebellar function and produce similar symptoms in patients. In order to understand the disease better, and define possible therapeutic targets for multiple SCAs, the field has been searching for common ground among the SCAs. In this review, we discuss the physiology of climbing fibers and the possibility that climbing fiber dysfunction is a point of convergence for at least a subset of SCAs.
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Affiliation(s)
- C J L M Smeets
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - D S Verbeek
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
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45
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Johenning FW, Theis AK, Pannasch U, Rückl M, Rüdiger S, Schmitz D. Ryanodine Receptor Activation Induces Long-Term Plasticity of Spine Calcium Dynamics. PLoS Biol 2015; 13:e1002181. [PMID: 26098891 PMCID: PMC4476683 DOI: 10.1371/journal.pbio.1002181] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 05/12/2015] [Indexed: 12/16/2022] Open
Abstract
A key feature of signalling in dendritic spines is the synapse-specific transduction of short electrical signals into biochemical responses. Ca2+ is a major upstream effector in this transduction cascade, serving both as a depolarising electrical charge carrier at the membrane and an intracellular second messenger. Upon action potential firing, the majority of spines are subject to global back-propagating action potential (bAP) Ca2+ transients. These transients translate neuronal suprathreshold activation into intracellular biochemical events. Using a combination of electrophysiology, two-photon Ca2+ imaging, and modelling, we demonstrate that bAPs are electrochemically coupled to Ca2+ release from intracellular stores via ryanodine receptors (RyRs). We describe a new function mediated by spine RyRs: the activity-dependent long-term enhancement of the bAP-Ca2+ transient. Spines regulate bAP Ca2+ influx independent of each other, as bAP-Ca2+ transient enhancement is compartmentalized and independent of the dendritic Ca2+ transient. Furthermore, this functional state change depends exclusively on bAPs travelling antidromically into dendrites and spines. Induction, but not expression, of bAP-Ca2+ transient enhancement is a spine-specific function of the RyR. We demonstrate that RyRs can form specific Ca2+ signalling nanodomains within single spines. Functionally, RyR mediated Ca2+ release in these nanodomains induces a new form of Ca2+ transient plasticity that constitutes a spine specific storage mechanism of neuronal suprathreshold activity patterns. A combination of two-photon calcium imaging, electrophysiology, and modelling shows how ryanodine receptors (a type of intracellular calcium channel) generate a signalling nanodomain within individual dendritic spines, enabling compartmentalized plasticity of calcium dynamics. Experiences change neuronal circuits, and these circuit changes outlast the initial experiences. This means that, in neurons, the fast electrical activity encoding experiences needs to be transduced into longer-lived biochemical and structural changes. A key mediator between these two timescales of neuronal activity is the Ca2+ ion. Ca2+ serves both as an electric charge carrier mediating fast voltage changes at the membrane and as a second messenger activating intracellular signalling cascades. Even within the spatial confines of dendritic spines, the specialized domains of dendrites that receive synaptic connections, Ca2+ encodes a versatile array of specific functions. In this study, we first demonstrate that voltage-gated Ca2+ channels and ryanodine receptors, intracellular channels located on the membrane of the endoplasmic reticulum through which Ca2+ can be released into the cytosol, are electrochemically coupled in single dendritic spines. We identify how ryanodine receptors induce enhancement of the Ca2+ influx, mediated by the opening of voltage-gated Ca2+ channels, induced by action potentials in a compartmentalized, spine-specific manner. Within the femtoliter volume of a single spine, specificity of this route of Ca2+-signalling is achieved by a signalling nanodomain centred on the ryanodine receptor. Our work stresses the role of the ryanodine receptor not only as an ion channel releasing Ca2+ from the endoplasmic reticulum but also as a macromolecular complex generating specificity of Ca2+-signalling within the spatial constraints of a single spine.
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Affiliation(s)
- Friedrich W. Johenning
- Neuroscience Research Center, Charité-Universitätsmedizin, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
- * E-mail:
| | - Anne-Kathrin Theis
- Neuroscience Research Center, Charité-Universitätsmedizin, Berlin, Germany
| | - Ulrike Pannasch
- Neuroscience Research Center, Charité-Universitätsmedizin, Berlin, Germany
| | - Martin Rückl
- Institute of Physics, Humboldt Universität, Berlin, Germany
| | - Sten Rüdiger
- Institute of Physics, Humboldt Universität, Berlin, Germany
| | - Dietmar Schmitz
- Neuroscience Research Center, Charité-Universitätsmedizin, Berlin, Germany
- Bernstein Center for Computational Neuroscience, Berlin, Germany
- Cluster of Excellence ‘NeuroCure’, Charité-Universitätsmedizin, Berlin, Germany
- DZNE- German Center for Neurodegenerative Diseases, Berlin, Germany
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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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Grasselli G, Hansel C. Cerebellar long-term potentiation: cellular mechanisms and role in learning. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 117:39-51. [PMID: 25172628 DOI: 10.1016/b978-0-12-420247-4.00003-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Activity-dependent long-term plasticity of synaptic transmission, such as in long-term potentiation (LTP) and long-term depression (LTD), provides a cellular correlate of experience-driven learning. While at excitatory synapses in the hippocampus and neocortex LTP is seen as the primary learning mechanism, it has been widely assumed that cerebellar motor learning is mediated by LTD at parallel fiber (PF)-Purkinje cell synapses instead. However, recent work on mouse mutants with deficits in AMPA receptor internalization has demonstrated that motor learning can occur in the absence of LTD, suggesting that LTD is not essential. Another recent study has shifted attention toward LTP at PF synapses, showing that blockade of LTP severely affects motor learning. Here, we review the cellular and molecular events that are involved in LTP induction and discuss whether LTP might indeed play a more significant role in cerebellar learning than previously anticipated.
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Affiliation(s)
- Giorgio Grasselli
- Department of Neurobiology, University of Chicago, Chicago, Illinois, USA
| | - Christian Hansel
- Department of Neurobiology, University of Chicago, Chicago, Illinois, USA.
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48
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Dendritic geometry shapes neuronal cAMP signalling to the nucleus. Nat Commun 2015; 6:6319. [PMID: 25692798 PMCID: PMC4346624 DOI: 10.1038/ncomms7319] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 01/16/2015] [Indexed: 12/12/2022] Open
Abstract
Neurons have complex dendritic trees, receiving numerous inputs at various distances from the cell body. Yet the rules of molecular signal propagation from dendrites to nuclei are unknown. DARPP-32 is a phosphorylation-regulated signalling hub in striatal output neurons. We combine diffusion-reaction modelling and live imaging to investigate cAMP-activated DARPP-32 signalling to the nucleus. The model predicts maximal effects on the nucleus of cAMP production in secondary dendrites, due to segmental decrease of dendrite diameter. Variations in branching, perikaryon size or spines have less pronounced effects. Biosensor kinase activity measurement following cAMP or dopamine uncaging confirms these predictions. Histone 3 phosphorylation, regulated by this pathway, is best stimulated by cAMP released in secondary-like dendrites. Thus, unexpectedly, the efficacy of diffusion-based signalling from dendrites to nucleus is not inversely proportional to the distance. We suggest a general mechanism by which dendritic geometry counterbalances the effect of dendritic distance for signalling to the nucleus.
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49
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Brown SA, Loew LM. Integration of modeling with experimental and clinical findings synthesizes and refines the central role of inositol 1,4,5-trisphosphate receptor 1 in spinocerebellar ataxia. Front Neurosci 2015; 8:453. [PMID: 25653583 PMCID: PMC4300941 DOI: 10.3389/fnins.2014.00453] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 12/22/2014] [Indexed: 12/22/2022] Open
Abstract
A suite of models was developed to study the role of inositol 1,4,5-trisphosphate receptor 1 (IP3R1) in spinocerebellar ataxias (SCAs). Several SCAs are linked to reduced abundance of IP3R1 or to supranormal sensitivity of the receptor to activation by its ligand inositol 1,4,5-trisphosphate (IP3). Detailed multidimensional models have been created to simulate biochemical calcium signaling and membrane electrophysiology in cerebellar Purkinje neurons. In these models, IP3R1-mediated calcium release is allowed to interact with ion channel response on the cell membrane. Experimental findings in mice and clinical observations in humans provide data input for the models. The SCA modeling suite helps interpret experimental results and provides suggestions to guide experiments. The models predict IP3R1 supersensitivity in SCA1 and compensatory mechanisms in SCA1, SCA2, and SCA3. Simulations explain the impact of calcium buffer proteins. Results show that IP3R1-mediated calcium release activates voltage-gated calcium-activated potassium channels in the plasma membrane. The SCA modeling suite unifies observations from experiments in a number of SCAs. The cadre of simulations demonstrates the central role of IP3R1.
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Affiliation(s)
| | - Leslie M Loew
- Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center Farmington, CT, USA
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50
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Macromolecular transport in synapse to nucleus communication. Trends Neurosci 2014; 38:108-16. [PMID: 25534890 DOI: 10.1016/j.tins.2014.12.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 12/01/2014] [Indexed: 12/21/2022]
Abstract
Local signaling events at synapses or axon terminals must be communicated to the nucleus to elicit transcriptional responses. The lengths of neuronal processes pose a significant challenge for such intracellular communication. This challenge is met by mechanisms ranging from rapid signals encoded in calcium waves to slower macromolecular signaling complexes carried by molecular motors. Here we summarize recent findings on macromolecular signaling from the synapse to the nucleus, in comparison to those employed in injury signaling along axons. A number of common themes emerge, including combinatorial signal encoding by post-translational mechanisms such as differential phosphorylation and proteolysis, and conserved roles for importins in coordinating signaling complexes. Neurons may integrate ionic flux with motor-transported signals as a temporal code for synaptic plasticity signaling.
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