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Dai J, Liakath-Ali K, Golf SR, Südhof TC. Distinct neurexin-cerebellin complexes control AMPA- and NMDA-receptor responses in a circuit-dependent manner. eLife 2022; 11:e78649. [PMID: 36205393 PMCID: PMC9586558 DOI: 10.7554/elife.78649] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 10/06/2022] [Indexed: 01/11/2023] Open
Abstract
At CA1→subiculum synapses, alternatively spliced neurexin-1 (Nrxn1SS4+) and neurexin-3 (Nrxn3SS4+) enhance NMDA-receptors and suppress AMPA-receptors, respectively, without affecting synapse formation. Nrxn1SS4+ and Nrxn3SS4+ act by binding to secreted cerebellin-2 (Cbln2) that in turn activates postsynaptic GluD1 receptors. Whether neurexin-Cbln2-GluD1 signaling has additional functions besides regulating NMDA- and AMPA-receptors, and whether such signaling performs similar roles at other synapses, however, remains unknown. Here, we demonstrate using constitutive Cbln2 deletions in mice that at CA1→subiculum synapses, Cbln2 performs no additional developmental roles besides regulating AMPA- and NMDA-receptors. Moreover, low-level expression of functionally redundant Cbln1 did not compensate for a possible synapse-formation function of Cbln2 at CA1→subiculum synapses. In exploring the generality of these findings, we examined the prefrontal cortex where Cbln2 was recently implicated in spinogenesis, and the cerebellum where Cbln1 is known to regulate parallel-fiber synapses. In the prefrontal cortex, Nrxn1SS4+-Cbln2 signaling selectively controlled NMDA-receptors without affecting spine or synapse numbers, whereas Nrxn3SS4+-Cbln2 signaling had no apparent role. In the cerebellum, conversely, Nrxn3SS4+-Cbln1 signaling regulated AMPA-receptors, whereas now Nrxn1SS4+-Cbln1 signaling had no manifest effect. Thus, Nrxn1SS4+- and Nrxn3SS4+-Cbln1/2 signaling complexes differentially control NMDA- and AMPA-receptors in different synapses in diverse neural circuits without regulating synapse or spine formation.
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Affiliation(s)
- Jinye Dai
- Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
- Department of Molecular and Cellular Physiology, Stanford UniversityStanfordUnited States
| | - Kif Liakath-Ali
- Department of Molecular and Cellular Physiology, Stanford UniversityStanfordUnited States
| | - Samantha Rose Golf
- Department of Molecular and Cellular Physiology, Stanford UniversityStanfordUnited States
| | - Thomas C Südhof
- Howard Hughes Medical Institute, Stanford UniversityStanfordUnited States
- Department of Molecular and Cellular Physiology, Stanford UniversityStanfordUnited States
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2
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Jackson T, Seifi M, Górecki DC, Swinny JD. Specific Dystrophins Selectively Associate with Inhibitory and Excitatory Synapses of the Mouse Cerebellum and their Loss Alters Expression of P2X7 Purinoceptors and Pro-Inflammatory Mediators. Cell Mol Neurobiol 2022; 42:2357-2377. [PMID: 34101068 PMCID: PMC9418305 DOI: 10.1007/s10571-021-01110-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 05/27/2021] [Indexed: 02/07/2023]
Abstract
Duchenne muscular dystrophy (DMD) patients, having mutations of the DMD gene, present with a range of neuropsychiatric disorders, in addition to the quintessential muscle pathology. The neurobiological basis remains poorly understood because the contributions of different DMD gene products (dystrophins) to the different neural networks underlying such symptoms are yet to be fully characterised. While full-length dystrophin clusters in inhibitory synapses, with inhibitory neurotransmitter receptors, the precise subcellular expression of truncated DMD gene products with excitatory synapses remains unresolved. Furthermore, inflammation, involving P2X purinoceptor 7 (P2RX7) accompanies DMD muscle pathology, yet any association with brain dystrophins is yet to be established. The aim of this study was to investigate the comparative expression of different dystrophins, alongside ionotropic glutamate receptors and P2RX7s, within the cerebellar circuitry known to express different dystrophin isoforms. Immunoreactivity for truncated DMD gene products was targeted to Purkinje cell (PC) distal dendrites adjacent to, or overlapping with, signal for GluA1, GluA4, GluN2A, and GluD2 receptor subunits. P2X7R immunoreactivity was located in Bergmann glia profiles adjacent to PC-dystrophin immunoreactivity. Ablation of all DMD gene products coincided with decreased mRNA expression for Gria2, Gria3, and Grin2a and increased GluD2 immunoreactivity. Finally, dystrophin-null mice showed decreased brain mRNA expression of P2rx7 and several inflammatory mediators. The data suggest that PCs target different dystrophin isoforms to molecularly and functionally distinct populations of synapses. In contrast to muscle, dystrophinopathy in brain leads to the dampening of the local immune system.
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Affiliation(s)
- Torquil Jackson
- School of Pharmacy & Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO12DT, UK
| | - Mohsen Seifi
- Leicester School of Pharmacy, De Montfort University, Leicester, LE1 9BH, UK
| | - Dariusz C Górecki
- School of Pharmacy & Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO12DT, UK
- Military Institute of Hygiene and Epidemiology, Kozielska 4, 01-001, Warsaw, Poland
| | - Jerome D Swinny
- School of Pharmacy & Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO12DT, UK.
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3
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Saviuk N, Chong Y, Wang P, Bermudez S, Zhao Z, Bhaskaran AA, Bowie D, Sonenberg N, Cooper E, Haghighi AP. Loss of 4E-BP converts cerebellar long-term depression to long-term potentiation. Cell Rep 2022; 39:110911. [PMID: 35675781 DOI: 10.1016/j.celrep.2022.110911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 10/31/2021] [Accepted: 05/12/2022] [Indexed: 11/17/2022] Open
Abstract
Genetic perturbances in translational regulation result in defects in cerebellar motor learning; however, little is known about the role of translational mechanisms in the regulation of cerebellar plasticity. We show that genetic removal of 4E-BP, a translational suppressor and target of mammalian target of rapamycin complex 1, results in a striking change in cerebellar synaptic plasticity. We find that cerebellar long-term depression (LTD) at parallel fiber-Purkinje cell synapses is converted to long-term potentiation in 4E-BP knockout mice. Biochemical and pharmacological experiments suggest that increased phosphatase activity largely accounts for the defects in LTD. Our results point to a model in which translational regulation through the action of 4E-BP plays a critical role in establishing the appropriate kinase/phosphatase balance required for normal synaptic plasticity in the cerebellum.
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Affiliation(s)
- Natasha Saviuk
- Integrated Program in Neuroscience, McGill University, Montréal, QC, Canada; Department of Physiology, McGill University, Montréal, QC, Canada
| | - Yumaine Chong
- Integrated Program in Neuroscience, McGill University, Montréal, QC, Canada; Department of Physiology, McGill University, Montréal, QC, Canada
| | - Peng Wang
- Biochemistry, McGill University, Montréal, QC, Canada
| | - Sara Bermudez
- Biochemistry, McGill University, Montréal, QC, Canada
| | - Zhe Zhao
- Integrated Program in Neuroscience, McGill University, Montréal, QC, Canada
| | - Arjun A Bhaskaran
- Integrated Program in Neuroscience, McGill University, Montréal, QC, Canada; Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada
| | - Derek Bowie
- Integrated Program in Neuroscience, McGill University, Montréal, QC, Canada; Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada
| | | | - Ellis Cooper
- Integrated Program in Neuroscience, McGill University, Montréal, QC, Canada; Department of Physiology, McGill University, Montréal, QC, Canada.
| | - A Pejmun Haghighi
- Integrated Program in Neuroscience, McGill University, Montréal, QC, Canada; Department of Physiology, McGill University, Montréal, QC, Canada; Buck Institute for Research on Aging, Novato, CA, USA.
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4
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Südhof TC. Synaptic Neurexin Complexes: A Molecular Code for the Logic of Neural Circuits. Cell 2017; 171:745-769. [PMID: 29100073 DOI: 10.1016/j.cell.2017.10.024] [Citation(s) in RCA: 471] [Impact Index Per Article: 67.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 10/04/2017] [Accepted: 10/15/2017] [Indexed: 10/18/2022]
Abstract
Synapses are specialized junctions between neurons in brain that transmit and compute information, thereby connecting neurons into millions of overlapping and interdigitated neural circuits. Here, we posit that the establishment, properties, and dynamics of synapses are governed by a molecular logic that is controlled by diverse trans-synaptic signaling molecules. Neurexins, expressed in thousands of alternatively spliced isoforms, are central components of this dynamic code. Presynaptic neurexins regulate synapse properties via differential binding to multifarious postsynaptic ligands, such as neuroligins, cerebellin/GluD complexes, and latrophilins, thereby shaping the input/output relations of their resident neural circuits. Mutations in genes encoding neurexins and their ligands are associated with diverse neuropsychiatric disorders, especially schizophrenia, autism, and Tourette syndrome. Thus, neurexins nucleate an overall trans-synaptic signaling network that controls synapse properties, which thereby determines the precise responses of synapses to spike patterns in a neuron and circuit and which is vulnerable to impairments in neuropsychiatric disorders.
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Affiliation(s)
- Thomas C Südhof
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University Medical School, 265 Campus Drive, CA 94305-5453, USA.
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5
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Valbuena S, Lerma J. Non-canonical Signaling, the Hidden Life of Ligand-Gated Ion Channels. Neuron 2017; 92:316-329. [PMID: 27764665 DOI: 10.1016/j.neuron.2016.10.016] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 10/03/2016] [Accepted: 10/06/2016] [Indexed: 12/25/2022]
Abstract
Neurotransmitter receptors are responsible for the transfer of information across the synapse. While ionotropic receptors form ion channels and mediate rapid membrane depolarization, so-called metabotropic receptors exert their action though slower, less direct intracellular signaling pathways. Glutamate, GABA, and acetylcholine can activate both ionotropic and metabotropic receptors, yet the distinction between these "canonical" signaling systems has become less clear since ionotropic receptors were proposed to also activate second messenger systems, defining a "non-canonical" signaling pathway. How these alternative pathways affect neuronal circuit activity is not well understood, and their influence could be more significant than previously anticipated. In this review, we examine the evidence available that supports the existence of parallel and unsuspected signaling pathways used by ionotropic neurotransmitter receptors.
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Affiliation(s)
- Sergio Valbuena
- Instituto de Neurociencias CSIC-UMH, 03550 San Juan de Alicante, Spain
| | - Juan Lerma
- Instituto de Neurociencias CSIC-UMH, 03550 San Juan de Alicante, Spain.
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6
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The Purkinje cell as a model of synaptogenesis and synaptic specificity. Brain Res Bull 2016; 129:12-17. [PMID: 27721030 DOI: 10.1016/j.brainresbull.2016.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 09/28/2016] [Accepted: 10/05/2016] [Indexed: 01/03/2023]
Abstract
Since the groundbreaking work of Ramon y Cajal, the cerebellar Purkinje cell has always represented an ideal model for studying the organization, development and function of synaptic circuits. Purkinje cells receive distinct types of glutamatergic and GABAergic synapses, each characterized by exquisite sub-cellular and molecular specificity. The formation and refinement of these connections results from a temporally-regulated sequence of events that involves molecular interactions between distinct sets of secreted and surface proteins, as well as activity-dependent competition between converging inputs. Insights into the mechanisms controlling synaptic specificity in Purkinje cells may help understand synapse development also in other brain regions and disclose circuit abnormalities that underlie neurodevelopmental disorders.
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7
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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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8
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Molecular and anatomical evidence for the input pathway- and target cell type-dependent regulation of glutamatergic synapses. Anat Sci Int 2015; 91:8-21. [DOI: 10.1007/s12565-015-0303-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 09/17/2015] [Indexed: 10/23/2022]
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9
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The Secreted Protein C1QL1 and Its Receptor BAI3 Control the Synaptic Connectivity of Excitatory Inputs Converging on Cerebellar Purkinje Cells. Cell Rep 2015; 10:820-832. [DOI: 10.1016/j.celrep.2015.01.034] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 01/08/2015] [Accepted: 01/15/2015] [Indexed: 11/21/2022] Open
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10
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Abstract
Across the nervous system, neurons form highly stereotypic patterns of synaptic connections that are designed to serve specific functions. Mature wiring patterns are often attained upon the refinement of early, less precise connectivity. Much work has led to the prevailing view that many developing circuits are sculpted by activity-dependent competition among converging afferents, which results in the elimination of unwanted synapses and the maintenance and strengthening of desired connections. Studies of the vertebrate retina, however, have recently revealed that activity can play a role in shaping developing circuits without engaging competition among converging inputs that differ in their activity levels. Such neurotransmission-mediated processes can produce stereotypic wiring patterns by promoting selective synapse formation rather than elimination. We discuss how the influence of transmission may also be limited by circuit design and further highlight the importance of transmission beyond development in maintaining wiring specificity and synaptic organization of neural circuits.
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11
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Polyglutamine-expanded ataxin-3 impairs long-term depression in Purkinje neurons of SCA3 transgenic mouse by inhibiting HAT and impairing histone acetylation. Brain Res 2014; 1583:220-9. [PMID: 25139423 DOI: 10.1016/j.brainres.2014.08.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 06/11/2014] [Accepted: 08/07/2014] [Indexed: 01/13/2023]
Abstract
Our previous study using a transgenic mouse model of spinocerebellar ataxia type 3 (SCA3) reported that disease-causing ataxin-3-Q79 caused cerebellar malfunction by inducing transcriptional downregulation. Long-term depression (LTD) of parallel fiber-Purkinje neuron glutamatergic transmission is believed to be a cellular mechanism for motor learning and motor coordination in the cerebellum. Downregulated mRNA expression of calcineurin B, IP3-R1, myosin Va and PLC β4, which are required for the induction of cerebellar LTD, led to an impairment of LTD induction in Purkinje neurons of SCA3 transgenic mouse. Our study suggested that ataxin-3-Q79 caused hypoacetylation of cerebellar histone H3 or H4 by inhibiting the activity of histone acetyltransferase (HAT) without affecting the activity of histone deacetylase (HDAC). Consistent with the hypothesis that hypoacetylated H3 or H4 histone associated with promoter regions of downregulated genes is the molecular mechanism underlying ataxin-3-Q79-induced transcriptional repression, chromatin immunoprecipitation-quantitative real-time PCR analysis showed hypoacetylation of H3 or H4 histone associated with the proximal promoter of downregulated calcineurin B, IP3-R1, myosin Va or PLC β4 gene in the cerebellum of SCA3 mouse. HDAC inhibitor sodium butyrate reversed ataxin-3-Q79-induced hypoacetylation of histone H3 or H4 associated with the proximal promoter of calcineurin B, IP3-R1, myosin Va or PLC β4 gene. Sodium butyrate also prevented ataxin-3-Q79-induced impairment of LTD induction in Purkinje neurons of SCA3 mice. Our results suggest that polyglutamine-expanded ataxin-3-Q79 impairs HAT activity, leading to histone hypoacetylation, downregulated expression of cerebellar genes required for LTD induction and impaired induction of cerebellar LTD in the SCA3 transgenic mouse.
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12
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Okawa H, Della Santina L, Schwartz GW, Rieke F, Wong ROL. Interplay of cell-autonomous and nonautonomous mechanisms tailors synaptic connectivity of converging axons in vivo. Neuron 2014; 82:125-37. [PMID: 24698272 DOI: 10.1016/j.neuron.2014.02.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2014] [Indexed: 11/24/2022]
Abstract
Neurons receive input from diverse afferents but form stereotypic connections with each axon type to execute their precise functions. Developmental mechanisms that specify the connectivity of individual axons across populations of converging afferents are not well-understood. Here, we untangled the contributions of activity-dependent and independent interactions that regulate the connectivity of afferents providing major and minor input onto a neuron. Individual transmission-deficient retinal bipolar cells (BCs) reduced synapses with retinal ganglion cells (RGCs), but active BCs of the same type sharing the dendrite surprisingly did not compensate for this loss. Genetic ablation of some BC neighbors resulted in increased synaptogenesis by the remaining axons in a transmission-independent manner. Presence, but not transmission, of the major BC input also dissuades wiring with the minor input and with synaptically compatible but functionally mismatched afferents. Cell-autonomous, activity-dependent and nonautonomous, activity-independent mechanisms thus together tailor connectivity of individual axons among converging inner retinal afferents.
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Affiliation(s)
- Haruhisa Okawa
- Department of Biological Structure, University of Washington, Seattle, WA 98195-7420, USA
| | - Luca Della Santina
- Department of Biological Structure, University of Washington, Seattle, WA 98195-7420, USA
| | - Gregory W Schwartz
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195-7290, USA; Howard Hughes Medical Institute, Seattle, WA 98195, USA
| | - Fred Rieke
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195-7290, USA; Howard Hughes Medical Institute, Seattle, WA 98195, USA
| | - Rachel O L Wong
- Department of Biological Structure, University of Washington, Seattle, WA 98195-7420, USA.
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13
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Striatal dopamine D1 receptor is essential for contextual fear conditioning. Sci Rep 2014; 4:3976. [PMID: 24496082 PMCID: PMC3913917 DOI: 10.1038/srep03976] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 01/17/2014] [Indexed: 01/18/2023] Open
Abstract
Fear memory is critical for animals to trigger behavioural adaptive responses to potentially threatening stimuli, while too much or inappropriate fear may cause psychiatric problems. Numerous studies have shown that the amygdala, hippocampus and medial prefrontal cortex play important roles in Pavlovian fear conditioning. Recently, we showed that striatal neurons are required for the formation of the auditory fear memory when the unconditioned stimulus is weak. Here, we found that selective ablation of striatal neurons strongly diminished contextual fear conditioning irrespective of the intensity of footshock. Furthermore, contextual fear conditioning was strongly reduced in striatum-specific dopamine D1 receptor knockout mice. On the other hand, striatum-specific dopamine D2 receptor knockout mice showed freezing responses comparable to those of control mice. These results suggest that striatal D1 receptor is essential for contextual fear conditioning.
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14
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Chia PH, Li P, Shen K. Cell biology in neuroscience: cellular and molecular mechanisms underlying presynapse formation. ACTA ACUST UNITED AC 2013; 203:11-22. [PMID: 24127213 PMCID: PMC3798257 DOI: 10.1083/jcb.201307020] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Synapse formation is a highly regulated process that requires the coordination of many cell biological events. Decades of research have identified a long list of molecular components involved in assembling a functioning synapse. Yet how the various steps, from transporting synaptic components to adhering synaptic partners and assembling the synaptic structure, are regulated and precisely executed during development and maintenance is still unclear. With the improvement of imaging and molecular tools, recent work in vertebrate and invertebrate systems has provided important insight into various aspects of presynaptic development, maintenance, and trans-synaptic signals, thereby increasing our understanding of how extrinsic organizers and intracellular mechanisms contribute to presynapse formation.
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Affiliation(s)
- Poh Hui Chia
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305
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15
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Jüttner R, Montag D, Craveiro RB, Babich A, Vetter P, Rathjen FG. Impaired presynaptic function and elimination of synapses at premature stages during postnatal development of the cerebellum in the absence of CALEB (CSPG5/neuroglycan C). Eur J Neurosci 2013; 38:3270-80. [PMID: 23889129 DOI: 10.1111/ejn.12313] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 06/17/2013] [Indexed: 12/25/2022]
Abstract
Chicken acidic leucine-rich EGF-like domain-containing brain protein (CALEB), also known as chondroitin sulfate proteoglycan (CSPG)5 or neuroglycan C, is a neural chondroitin sulfate-containing and epidermal growth factor (EGF)-domain-containing transmembrane protein that is implicated in synaptic maturation. Here, we studied the role of CALEB within the developing cerebellum. Adult CALEB-deficient mice displayed impaired motor coordination in Rota-Rod experiments. Analysis of the neuronal connectivity of Purkinje cells by patch-clamp recordings demonstrated impairments of presynaptic maturation of inhibitory synapses. GABAergic synapses on Purkinje cells revealed decreased evoked amplitudes, altered paired-pulse facilitation and reduced depression after repetitive stimulation at early postnatal but not at mature stages. Furthermore, the elimination of supernumerary climbing fiber synapses on Purkinje cells was found to occur at earlier developmental stages in the absence of CALEB. For example, at postnatal day 8 in wild-type mice, 54% of Purkinje cells had three or more climbing fiber synapses in contrast to mutants where this number was decreased to less than 25%. The basic properties of the climbing fiber Purkinje cell synapse remained unaffected. Using Sholl analysis of dye-injected Purkinje cells we revealed that the branching pattern of the dendritic tree of Purkinje cells was not impaired in CALEB-deficient mice. The alterations observed by patch-clamp recordings correlated with a specific pattern and timing of expression of CALEB in Purkinje cells, i.e. it is dynamically regulated during development from a high chondroitin sulfate-containing form to a non-chondroitin sulfate-containing form. Thus, our results demonstrated an involvement of CALEB in the presynaptic differentiation of cerebellar GABAergic synapses and revealed a new role for CALEB in synapse elimination in Purkinje cells.
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Affiliation(s)
- René Jüttner
- Max-Delbrück-Centrum, Robert-Rössle-Straße 10, 13092, Berlin, Germany
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16
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Contribution of Postsynaptic GluD2 to Presynaptic R-type Ca2+ Channel Function, Glutamate Release and Long-term Potentiation at Parallel Fiber to Purkinje Cell Synapses. THE CEREBELLUM 2013; 12:657-66. [DOI: 10.1007/s12311-013-0474-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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17
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Reeber SL, White JJ, George-Jones NA, Sillitoe RV. Architecture and development of olivocerebellar circuit topography. Front Neural Circuits 2013; 6:115. [PMID: 23293588 PMCID: PMC3534185 DOI: 10.3389/fncir.2012.00115] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 12/12/2012] [Indexed: 11/21/2022] Open
Abstract
The cerebellum has a simple tri-laminar structure that is comprised of relatively few cell types. Yet, its internal micro-circuitry is anatomically, biochemically, and functionally complex. The most striking feature of cerebellar circuit complexity is its compartmentalized topography. Each cell type within the cerebellar cortex is organized into an exquisite map; molecular expression patterns, dendrite projections, and axon terminal fields divide the medial-lateral axis of the cerebellum into topographic sagittal zones. Here, we discuss the mechanisms that establish zones and highlight how gene expression and neural activity contribute to cerebellar pattern formation. We focus on the olivocerebellar system because its developmental mechanisms are becoming clear, its topographic termination patterns are very precise, and its contribution to zonal function is debated. This review deconstructs the architecture and development of the olivocerebellar pathway to provide an update on how brain circuit maps form and function.
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Affiliation(s)
- Stacey L Reeber
- Department of Pathology and Immunology, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital Houston, TX, USA ; Department of Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital Houston, TX, USA
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18
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Hirano T. Long-term depression and other synaptic plasticity in the cerebellum. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2013; 89:183-195. [PMID: 23666089 PMCID: PMC3722574 DOI: 10.2183/pjab.89.183] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 02/28/2013] [Indexed: 06/02/2023]
Abstract
Cerebellar long-term depression (LTD) is a type of synaptic plasticity and has been considered as a critical cellular mechanism for motor learning. LTD occurs at excitatory synapses between parallel fibers and a Purkinje cell in the cerebellar cortex, and is expressed as reduced responsiveness to transmitter glutamate. Molecular induction mechanism of LTD has been intensively studied using culture and slice preparations, which has revealed critical roles of Ca(2+), protein kinase C and endocytosis of AMPA-type glutamate receptors. Involvement of a large number of additional molecules has also been demonstrated, and their interactions relevant to LTD mechanisms have been studied. In vivo experiments including those on mutant mice, have reported good correlation of LTD and motor learning. However, motor learning could occur with impaired LTD. A possibility that cerebellar synaptic plasticity other than LTD compensates for the defective LTD has been proposed.
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Affiliation(s)
- Tomoo Hirano
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan.
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Isope P, Hildebrand ME, Snutch TP. Contributions of T-type voltage-gated calcium channels to postsynaptic calcium signaling within Purkinje neurons. THE CEREBELLUM 2012; 11:651-65. [PMID: 20734177 PMCID: PMC3411289 DOI: 10.1007/s12311-010-0195-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Low threshold voltage-gated T-type calcium channels have long been implicated in the electrical excitability and calcium signaling of cerebellar Purkinje neurons although the molecular composition, localization, and modulation of T-type channels within Purkinje cells have only recently been addressed. The specific functional roles that T-type channels play in local synaptic integration within Purkinje spines are also currently being unraveled. Overall, Purkinje neurons represent a powerful model system to explore the potential roles of postsynaptic T-type channels throughout the nervous system. In this review, we present an overview of T-type calcium channel biophysical, pharmacological, and physiological characteristics that provides a foundation for understanding T-type channels within Purkinje neurons. We also describe the biophysical properties of T-type channels in context of other voltage-gated calcium channel currents found within Purkinje cells. The data thus far suggest that one specific T-type isoform, Cav3.1, is highly expressed within Purkinje spines and both physically and functionally couples to mGluR1 and other effectors within putative signaling microdomains. Finally, we discuss how the selective potentiation of Cav3.1 channels via activation of mGluR1 by parallel fiber inputs affects local synaptic integration and how this interaction may relate to the overall excitability of Purkinje neuron dendrites.
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Affiliation(s)
- Philippe Isope
- Institut des Neurosciences Cellulaires et Intégratives, CNRS-Université de Strasbourg, 5 rue Blaise Pascal, Strasbourg, France.
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20
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Glutamate-receptor-like molecule GluRδ2 involved in synapse formation at parallel fiber-Purkinje neuron synapses. THE CEREBELLUM 2012; 11:71-7. [PMID: 20387025 DOI: 10.1007/s12311-010-0170-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Glutamate-receptor-like molecule δ2 (GluRδ2, GluD2) has been classified as an ionotropic glutamate receptor subunit. It is selectively expressed on the postsynaptic membrane at parallel fiber-Purkinje neuron synapses in the cerebellum. Mutant mice deficient in GluRδ2 show impaired synaptic plasticity, the decrease in the number of parallel fiber-Purkinje neuron synapses, multiple innervation of climbing fibers on a Purkinje neuron, and defects in motor control and learning. Thus, GluRδ2 plays crucial roles in the cerebellar function. Recent studies on GluRδ2 have shown that it has synaptogenic activity. GluRδ2 expressed in a non-neuronal cell induces presynaptic differentiation of granule neurons in a co-culture preparation. This synaptogenic activity depends on an extracellular N-terminal leucine/isoleucine/valine binding protein-like domain of GluRδ2. GluRδ2 plays critical roles in formation, maturation, and/or maintenance of granule neuron-Purkinje neuron synapses.
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21
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Mishina M, Uemura T, Yasumura M, Yoshida T. Molecular mechanism of parallel fiber-Purkinje cell synapse formation. Front Neural Circuits 2012. [PMID: 23189042 PMCID: PMC3505014 DOI: 10.3389/fncir.2012.00090] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The cerebellum receives two excitatory afferents, the climbing fiber (CF) and the mossy fiber-parallel fiber (PF) pathway, both converging onto Purkinje cells (PCs) that are the sole neurons sending outputs from the cerebellar cortex. Glutamate receptor δ2 (GluRδ2) is expressed selectively in cerebellar PCs and localized exclusively at the PF-PC synapses. We found that a significant number of PC spines lack synaptic contacts with PF terminals and some of residual PF-PC synapses show mismatching between pre- and postsynaptic specializations in conventional and conditional GluRδ2 knockout mice. Studies with mutant mice revealed that in addition to PF-PC synapse formation, GluRδ2 is essential for synaptic plasticity, motor learning, and the restriction of CF territory. GluRδ2 regulates synapse formation through the amino-terminal domain, while the control of synaptic plasticity, motor learning, and CF territory is mediated through the carboxyl-terminal domain. Thus, GluRδ2 is the molecule that bridges synapse formation and motor learning. We found that the trans-synaptic interaction of postsynaptic GluRδ2 and presynaptic neurexins (NRXNs) through cerebellin 1 (Cbln1) mediates PF-PC synapse formation. The synaptogenic triad is composed of one molecule of tetrameric GluRδ2, two molecules of hexameric Cbln1 and four molecules of monomeric NRXN. Thus, GluRδ2 triggers synapse formation by clustering four NRXNs. These findings provide a molecular insight into the mechanism of synapse formation in the brain.
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Affiliation(s)
- Masayoshi Mishina
- Brain Science Laboratory, The Research Organization of Science and Technology, Ritsumeikan University Shiga, Japan ; Molecular Neurobiology and Pharmacology, Graduate School of Medicine, The University of Tokyo Tokyo, Japan
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Kaneko M, Yamaguchi K, Eiraku M, Sato M, Takata N, Kiyohara Y, Mishina M, Hirase H, Hashikawa T, Kengaku M. Remodeling of monoplanar Purkinje cell dendrites during cerebellar circuit formation. PLoS One 2011; 6:e20108. [PMID: 21655286 PMCID: PMC3105010 DOI: 10.1371/journal.pone.0020108] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Accepted: 04/02/2011] [Indexed: 11/18/2022] Open
Abstract
Dendrite arborization patterns are critical determinants of neuronal connectivity and integration. Planar and highly branched dendrites of the cerebellar Purkinje cell receive specific topographical projections from two major afferent pathways; a single climbing fiber axon from the inferior olive that extend along Purkinje dendrites, and parallel fiber axons of granule cells that contact vertically to the plane of dendrites. It has been believed that murine Purkinje cell dendrites extend in a single parasagittal plane in the molecular layer after the cell polarity is determined during the early postnatal development. By three-dimensional confocal analysis of growing Purkinje cells, we observed that mouse Purkinje cells underwent dynamic dendritic remodeling during circuit maturation in the third postnatal week. After dendrites were polarized and flattened in the early second postnatal week, dendritic arbors gradually expanded in multiple sagittal planes in the molecular layer by intensive growth and branching by the third postnatal week. Dendrites then became confined to a single plane in the fourth postnatal week. Multiplanar Purkinje cells in the third week were often associated by ectopic climbing fibers innervating nearby Purkinje cells in distinct sagittal planes. The mature monoplanar arborization was disrupted in mutant mice with abnormal Purkinje cell connectivity and motor discoordination. The dendrite remodeling was also impaired by pharmacological disruption of normal afferent activity during the second or third postnatal week. Our results suggest that the monoplanar arborization of Purkinje cells is coupled with functional development of the cerebellar circuitry.
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Affiliation(s)
- Megumi Kaneko
- Laboratory for Neural Cell Polarity, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Kazuhiko Yamaguchi
- Laboratory for Memory and Learning, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Mototsugu Eiraku
- Laboratory for Neural Cell Polarity, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Motohiko Sato
- Institute for Integrated Cell-Material Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Norio Takata
- Hirase Research Unit, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Yoshimoto Kiyohara
- Laboratory for Neural Architecture, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Masayoshi Mishina
- Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Hajime Hirase
- Hirase Research Unit, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Tsutomu Hashikawa
- Laboratory for Neural Architecture, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Mineko Kengaku
- Laboratory for Neural Cell Polarity, RIKEN Brain Science Institute, Wako, Saitama, Japan
- Institute for Integrated Cell-Material Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
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Glutamate receptor δ2 is essential for input pathway-dependent regulation of synaptic AMPAR contents in cerebellar Purkinje cells. J Neurosci 2011; 31:3362-74. [PMID: 21368048 DOI: 10.1523/jneurosci.5601-10.2011] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The number of synaptic AMPA receptors (AMPARs) is the major determinant of synaptic strength and is differently regulated in input pathway-dependent and target cell type-dependent manners. In cerebellar Purkinje cells (PCs), the density of synaptic AMPARs is approximately five times lower at parallel fiber (PF) synapses than at climbing fiber (CF) synapses. However, molecular mechanisms underlying this biased synaptic distribution remain unclear. As a candidate molecule, we focused on glutamate receptor δ2 (GluRδ2 or GluD2), which is known to be efficiently trafficked to and selectively expressed at PF synapses in PCs. We applied postembedding immunogold electron microscopy to GluRδ2 knock-out (KO) and control mice, and measured labeling density for GluA1-4 at three excitatory synapses in the cerebellar molecular layer. In both control and GluRδ2-KO mice, GluA1-3 were localized at PF and CF synapses in PCs, while GluA2-4 were at PF synapses in interneurons. In control mice, labeling density for each of GluA1-3 was four to six times lower at PF-PC synapses than at CF-PC synapses. In GluRδ2-KO mice, however, their labeling density displayed a three- to fivefold increase at PF synapses, but not at CF synapses, thus effectively eliminating input pathway-dependent disparity between the two PC synapses. Furthermore, we found an unexpected twofold increase in labeling density for GluA2 and GluA3, but not GluA4, at PF-interneuron synapses, where we identified low but significant expression of GluRδ2. These results suggest that GluRδ2 is involved in a common mechanism that restricts the number of synaptic AMPARs at PF synapses in PCs and molecular layer interneurons.
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van Welie I, Smith IT, Watt AJ. The metamorphosis of the developing cerebellar microcircuit. Curr Opin Neurobiol 2011; 21:245-53. [PMID: 21353528 PMCID: PMC3096781 DOI: 10.1016/j.conb.2011.01.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Accepted: 01/29/2011] [Indexed: 10/29/2022]
Abstract
The cerebellar cortical circuit with its organized and repetitive structure provides an excellent model system for studying how brain circuits are formed during development. The emergence of the mature brain requires that appropriate synaptic connections are formed and refined, which in the rodent cerebellum occurs primarily during the first three postnatal weeks. Developing circuits typically differ substantially from their mature counterparts, which suggests that development may not simply involve synaptic refinement, but rather involves restructuring of key synaptic components and network connections, in a manner reminiscent of metamorphosis. Here, we discuss recent evidence that, taken together, suggests that transient features of developing cerebellar synapses may act to coordinate network activity, and thereby shape the development of the cerebellar microcircuit.
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Affiliation(s)
- Ingrid van Welie
- Wolfson Institute for Biomedical Research, University College London, London, WC1E 6BT, United Kingdom
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25
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Yadav R, Rimerman R, Scofield MA, Dravid SM. Mutations in the transmembrane domain M3 generate spontaneously open orphan glutamate δ1 receptor. Brain Res 2011; 1382:1-8. [PMID: 21215726 DOI: 10.1016/j.brainres.2010.12.086] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 12/28/2010] [Accepted: 12/30/2010] [Indexed: 12/22/2022]
Abstract
Glutamate delta-1 receptors (GluRδ1) are expressed in the adult hippocampus and inner ear and have recently been shown to be important for high-frequency hearing. Similar to the closest homolog glutamate delta-2 receptor (GluRδ2), no agonist-induced currents are observed from GluRδ1 receptors. In an effort to understand the function of the GluRδ1 subunit, we probed the conserved transmembrane 3 (TM3) region of the GluRδ1 subunit, where the GluRδ2 lurcher mutation is localized. Four mutations in the TM3 domain A650C, L652A, A654C, and F655A resulted in spontaneously open GluRδ1 channels suggesting that GluRδ1 receptors can form homomeric receptors. The leak currents were partially blocked by pentamidine but showed negligible inhibition by NASP. It has been demonstrated that extracellular Ca(2+) binds and stabilizes the ligand binding domain (LBD) dimer interface leading to potentiation of currents through GluRδ2(Lc) channels. We found that extracellular Ca(2+) potentiated the spontaneous currents through GluRδ1F655A suggesting that extracellular Ca(2+) may interact with the conserved residues at GluRδ1 LBD dimer interface. A recent study suggested that d-serine and glycine bind to the GluRδ2 LBD and reduce spontaneous currents through the GluRδ2(Lc) channels. d-Serine and glycine produced only a modest reduction of spontaneous currents through GluRδ1F655A and had no effect on the spontaneous current through GluRδ1L652A. However, spontaneous currents in a chimeric GluRδ1-δ2(Lc) were robustly inhibited by d-serine. These results suggest that the activation gate is conserved in GluRδ1 receptors. Moreover, the conformational changes induced by d-serine and extracellular Ca(2+) are conserved among GluRδ1 and GluRδ2 receptors.
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Affiliation(s)
- Roopali Yadav
- Department of Pharmacology, Creighton University School of Medicine, 2500 California Plaza, Omaha, NE 68178, USA
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26
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Ablation of glutamate receptor GluRδ2 in adult Purkinje cells causes multiple innervation of climbing fibers by inducing aberrant invasion to parallel fiber innervation territory. J Neurosci 2010; 30:15196-209. [PMID: 21068325 DOI: 10.1523/jneurosci.0934-10.2010] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Glutamate receptor GluRδ2 is exclusively expressed in Purkinje cells (PCs) from early development and plays key roles in parallel fiber (PF) synapse formation, elimination of surplus climbing fibers (CFs), long-term depression, motor coordination, and motor learning. To address its role in adulthood, we previously developed a mouse model of drug-induced GluRδ2 ablation in adult PCs (Takeuchi et al., 2005). In that study, we demonstrated an essential role to maintain the connectivity of PF-PC synapses, based on the observation that both mismatching of presynaptic and postsynaptic specializations and disconnection of PF-PC synapses are progressively increased after GluRδ2 ablation. Here, we pursued its role for CF wiring in adult cerebellum. In parallel with the disconnection of PF-PC synapses, ascending CF branches exhibited distal extension to innervate distal dendrites of the target and neighboring PCs. Furthermore, transverse CF branches, a short motile collateral rarely forming synapses in wild-type animals, displayed aberrant mediolateral extension to innervate distal dendrites of neighboring and remote PCs. Consequently, many PCs were wired by single main CF and other surplus CFs innervating a small part of distal dendrites. Electrophysiological recording further revealed that surplus CF-EPSCs characterized with slow rise time and small amplitude emerged after GluRδ2 ablation, and increased progressively both in number and amplitude. Therefore, GluRδ2 is essential for maintaining CF monoinnervation in adult cerebellum by suppressing aberrant invasion of CF branches to the territory of PF innervation. Thus, GluRδ2 fuels heterosynaptic competition and gives PFs the competitive advantages over CFs throughout the animal's life.
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27
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Development of an anatomical technique for visualizing the mode of climbing fiber innervation in Purkinje cells and its application to mutant mice lacking GluRδ2 and Ca(v)2.1. Anat Sci Int 2010; 86:10-8. [PMID: 21153457 DOI: 10.1007/s12565-010-0095-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 09/27/2010] [Indexed: 02/07/2023]
Abstract
In the adult cerebellum, a single climbing fiber (CF) innervates proximal dendrites of Purkinje cells (PCs). This monoinnervation is established by the developmental elimination of surplus CFs through homosynaptic competition among multiply innervating CFs and heterosynaptic competition between CFs and parallel fibers, i.e., granule cell axons innervating distal PC dendrites. Although the developmental process of CF monoinnervation and defects in it in mutant and experimental animal models have been extensively studied by electrophysiological techniques, for quite some time this subject was poorly understood from a morphological perspective due to a lack of neuroanatomical methods that could distinguish CFs with different neuronal origins. Soon after the identification of type 2 vesicular glutamate transporter (VGluT2) that selectively detects CF terminals in the molecular layer, we developed a novel method of combined anterograde tracer labeling and VGluT2 immunohistochemistry. This method enables us to identify the mode (mono vs. multiple) of CF innervation and the site of multiple innervation. Since then, we have applied this method to various kinds of gene-manipulated mice manifesting ataxia and other cerebellar phenotypes. In this review, we summarize experimental procedures for the combined tracer/VGluT2 labeling method, and then introduce what we have learned by applying this method in studies on the role of GluRδ2 and Ca(v)2.1 in CF monoinnervation. This method has provided informative anatomical correlates to electrophysiological data and vice versa, and will extend our knowledge of the molecular and cellular mechanisms for the development, plasticity, degeneration, and repair of the CF-PC projection system.
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28
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Yuzaki M. Synapse formation and maintenance by C1q family proteins: a new class of secreted synapse organizers. Eur J Neurosci 2010; 32:191-7. [PMID: 20646056 DOI: 10.1111/j.1460-9568.2010.07346.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Several C1q family members, especially the Cbln and C1q-like subfamilies, are highly and predominantly expressed in the central nervous system. Cbln1, a member of the Cbln subfamily, plays two unique roles at parallel fiber (PF)-Purkinje cell synapses in the cerebellum: the formation and stabilization of synaptic contact, and the control of functional synaptic plasticity by regulating the postsynaptic endocytotic pathway. The delta2 glutamate receptor (GluD2), which is predominantly expressed in Purkinje cells, plays similar critical roles in the cerebellum. In addition, viral expression of GluD2 or the application of recombinant Cbln1 induces PF-Purkinje cell synaptogenesis in vitro and in vivo. Antigen-unmasking methods were necessary to reveal the immunoreactivities for endogenous Cbln1 and GluD2 at the synaptic junction of PF synapses. We propose that Cbln1 and GluD2 are located at the synaptic cleft, where various proteins undergo intricate molecular interactions with each other, and serve as a bidirectional synaptic organizer.
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Affiliation(s)
- Michisuke Yuzaki
- Department of Physiology, School of Medicine, Keio University, Shinjuku-ku, Tokyo, Japan.
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29
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Trans-synaptic interaction of GluRdelta2 and Neurexin through Cbln1 mediates synapse formation in the cerebellum. Cell 2010; 141:1068-79. [PMID: 20537373 DOI: 10.1016/j.cell.2010.04.035] [Citation(s) in RCA: 361] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 03/10/2010] [Accepted: 04/09/2010] [Indexed: 11/24/2022]
Abstract
Elucidation of molecular mechanisms that regulate synapse formation is required for the understanding of neural wiring, higher brain functions, and mental disorders. Despite the wealth of in vitro information, fundamental questions about how glutamatergic synapses are formed in the mammalian brain remain unanswered. Glutamate receptor (GluR) delta2 is essential for cerebellar synapse formation in vivo. Here, we show that the N-terminal domain (NTD) of GluRdelta2 interacts with presynaptic neurexins (NRXNs) through cerebellin 1 precursor protein (Cbln1). The synaptogenic activity of GluRdelta2 is abolished in cerebellar primary cultures from Cbln1 knockout mice and is restored by recombinant Cbln1. Knockdown of NRXNs in cerebellar granule cells also hinders the synaptogenic activity of GluRdelta2. Both the NTD of GluRdelta2 and the extracellular domain of NRXN1beta suppressed the synaptogenic activity of Cbln1 in cerebellar primary cultures and in vivo. These results suggest that GluRdelta2 mediates cerebellar synapse formation by interacting with presynaptic NRXNs through Cbln1.
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30
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Torashima T, Iizuka A, Horiuchi H, Mitsumura K, Yamasaki M, Koyama C, Takayama K, Iino M, Watanabe M, Hirai H. Rescue of abnormal phenotypes in δ2 glutamate receptor-deficient mice by the extracellular N-terminal and intracellular C-terminal domains of the δ2 glutamate receptor. Eur J Neurosci 2009; 30:355-65. [DOI: 10.1111/j.1460-9568.2009.06841.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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31
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The N-terminal domain of GluD2 (GluRdelta2) recruits presynaptic terminals and regulates synaptogenesis in the cerebellum in vivo. J Neurosci 2009; 29:5738-48. [PMID: 19420242 DOI: 10.1523/jneurosci.6013-08.2009] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The delta2 glutamate receptor (GluRdelta2; GluD2), which is predominantly expressed on postsynaptic sites at parallel fiber (PF)-Purkinje cell synapses in the cerebellum, plays two crucial roles in the cerebellum: the formation of PF synapses and the regulation of long-term depression (LTD), a form of synaptic plasticity underlying motor learning. Although the induction of LTD and motor learning absolutely require signaling via the cytoplasmic C-terminal domain of GluD2, the mechanisms by which GluD2 regulates PF synaptogenesis have remained unclear. Here, we examined the role of the extracellular N-terminal domain (NTD) of GluD2 on PF synaptogenesis by injecting Sindbis virus carrying wild-type (GluD2(wt)) or mutant GluD2 into the subarachnoid supracerebellar space of GluD2-null mice. Remarkably, the expression of GluD2(wt), but not of a mutant GluD2 lacking the NTD (GluD2(DeltaNTD)), rapidly induced PF synapse formation and rescued gross motor dyscoordination in adult GluD2-null mice just 1 d after injection. In addition, although the kainate receptor GluR6 (GluK2) did not induce PF synaptogenesis, a chimeric GluK2 that contained the NTD of GluD2 (GluD2(NTD)-GluK2) did. Similarly, GluD2(wt) and GluD2(NTD)-GluK2, but not GluD2(DeltaNTD), induced synaptogenesis in heterologous cells in vitro. In contrast, LTD was restored in GluD2-null Purkinje cells expressing a mutant GluD2 lacking the NTD. These results indicate that the NTD of GluD2 is necessary and sufficient for the function of GluD2 in the regulation of PF-Purkinje cell synaptogenesis. Furthermore, our results suggest that GluD2 differently regulates PF synaptogenesis and cerebellar LTD through the extracellular NTD and the cytoplasmic C-terminal end, respectively.
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32
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Kano M, Hashimoto K. Synapse elimination in the central nervous system. Curr Opin Neurobiol 2009; 19:154-61. [PMID: 19481442 DOI: 10.1016/j.conb.2009.05.002] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Accepted: 05/01/2009] [Indexed: 10/20/2022]
Abstract
Functional neural circuit formation during postnatal development involves the elimination of early-formed redundant synapses. In the neonatal mouse cerebellum, each Purkinje cell is innervated by multiple climbing fibers (CFs). Their synaptic strengths are initially uniform but one CF strengthens relative to other CFs during the first postnatal week. Then the weaker CFs are eliminated during the second postnatal week. Projections from the retina to the lateral geniculate nucleus (LGN) undergo similar developmental changes, that is the elimination of the majority of inputs and strengthening of a few afferents that remain. Recent studies have clarified that in both cerebellum and LGN, synapse refinement consists of multiple phases and that distinct types of neural activity drive synaptic remodeling in each developmental phase.
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Affiliation(s)
- Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan.
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33
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Galante M, Jani H, Vanes L, Daniel H, Fisher EMC, Tybulewicz VLJ, Bliss TVP, Morice E. Impairments in motor coordination without major changes in cerebellar plasticity in the Tc1 mouse model of Down syndrome. Hum Mol Genet 2009; 18:1449-63. [PMID: 19181682 PMCID: PMC2664148 DOI: 10.1093/hmg/ddp055] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Down syndrome (DS) is a genetic disorder arising from the presence of a third copy of human chromosome 21 (Hsa21). Recently, O'Doherty et al. [An aneuploid mouse strain carrying human chromosome 21 with Down syndrome phenotypes. Science 309 (2005) 2033–2037] generated a trans-species aneuploid mouse line (Tc1) that carries an almost complete Hsa21. The Tc1 mouse is the most complete animal model for DS currently available. Tc1 mice show many features that relate to human DS, including alterations in memory, synaptic plasticity, cerebellar neuronal number, heart development and mandible size. Because motor deficits are one of the most frequently occurring features of DS, we have undertaken a detailed analysis of motor behaviour in cerebellum-dependent learning tasks that require high motor coordination and balance. In addition, basic electrophysiological properties of cerebellar circuitry and synaptic plasticity have been investigated. Our results reveal that, compared with controls, Tc1 mice exhibit a higher spontaneous locomotor activity, a reduced ability to habituate to their environments, a different gait and major deficits on several measures of motor coordination and balance in the rota rod and static rod tests. Moreover, cerebellar long-term depression is essentially normal in Tc1 mice, with only a slight difference in time course. Our observations provide further evidence that support the validity of the Tc1 mouse as a model for DS, which will help us to provide insights into the causal factors responsible for motor deficits observed in persons with DS.
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Affiliation(s)
- Micaela Galante
- Laboratoire de Pharmacologie de la Synapse, CNRS UMR 8619, Université Paris-Sud, 91405 Orsay Cedex, France
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34
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An orphan ionotropic glutamate receptor: The δ2 subunit. Neuroscience 2009; 158:67-77. [DOI: 10.1016/j.neuroscience.2008.02.050] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 02/13/2008] [Accepted: 02/22/2008] [Indexed: 11/24/2022]
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35
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Hashimoto K, Yoshida T, Sakimura K, Mishina M, Watanabe M, Kano M. Influence of parallel fiber-Purkinje cell synapse formation on postnatal development of climbing fiber-Purkinje cell synapses in the cerebellum. Neuroscience 2008; 162:601-11. [PMID: 19166909 DOI: 10.1016/j.neuroscience.2008.12.037] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Revised: 12/08/2008] [Accepted: 12/24/2008] [Indexed: 11/29/2022]
Abstract
The climbing fiber (CF) to Purkinje cell (PC) synapse in the cerebellum provides an ideal model for the study of developmental rearrangements of neural circuits. At birth, each PC is innervated by multiple CFs. These surplus CFs are eliminated during postnatal development, and mono innervation is attained by postnatal day 20 (P20) in mice. Earlier studies on spontaneous mutant mice and animals with "hypogranular" cerebella indicate that regression of surplus CFs requires normal generation of granule cells and their axons, parallel fibers (PFs), and normal formation of PF-PC synapses. Our understanding of how PF-PC synapse formation affects development of CF-PC synapse has been greatly advanced by analyses of mutant mice deficient in glutamate receptor delta2 subunit (GluRdelta2), an orphan receptor expressed selectively in PCs. Deletion of GluRdelta2 results in impairment of PF-PC synapse formation, which leads to defects in development of CF-PC synapses. In this article, we review how impaired PF-PC synapse formation affects wiring of CFs to PCs based mostly on our data on GluRdelta2 knockout mice. We propose a new scheme that CF-PC synapses are shaped by the three consecutive events, namely functional differentiation of multiple CFs into one strong and a few weak inputs from P3 to P7, "early phase" of CF synapse elimination from P7 to around P11, and "late phase" of CF synapse elimination from around P12. Normal PF-PC synapse formation is required for the "late phase" of CF synapse elimination.
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Affiliation(s)
- K Hashimoto
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Yuzaki M. New (but old) molecules regulating synapse integrity and plasticity: Cbln1 and the delta2 glutamate receptor. Neuroscience 2008; 162:633-43. [PMID: 19124061 DOI: 10.1016/j.neuroscience.2008.12.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Revised: 12/01/2008] [Accepted: 12/03/2008] [Indexed: 11/28/2022]
Abstract
The delta2 glutamate receptor (GluRdelta2) is predominantly expressed in cerebellar Purkinje cells and plays crucial roles in cerebellar functions: GluRdelta2-null mice display ataxia and impaired motor learning. Interestingly, the contact state of synapses between parallel fibers (PFs) and Purkinje cells is specifically and severely affected, and the number of normal PF synapses is markedly reduced in GluRdelta2-null Purkinje cells. Furthermore, long-term depression at PF-Purkinje cell synapses is abrogated. Cbln1, a member of the C1q/tumor necrosis factor (TNF) superfamily, is predominantly expressed and released from cerebellar granule cells. Unexpectedly, the behavioral, physiological and anatomical phenotypes of cbln1-null mice precisely mimic those of GluRdelta2-null mice. Thus, we propose that Cbln1, which is released from granule cells, and GluRdelta2, which is predominantly expressed in Purkinje cells, are involved in a common signaling pathway crucial for synapse formation/maintenance and plasticity in the cerebellum. Since molecules related to Cbln1 are expressed in various brain regions other than the cerebellum, other C1q/TNF superfamily proteins may also regulate various aspects of synapses in the CNS. Therefore, an understanding of the signaling mechanisms underlying Cbln1 and GluRdelta2 in the cerebellum will provide new insights into the roles of C1q/TNF superfamily proteins as new cytokines that regulate normal and abnormal brain functions.
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Affiliation(s)
- M Yuzaki
- Department of Neurophysiology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
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Uemura T, Mishina M. The amino-terminal domain of glutamate receptor delta2 triggers presynaptic differentiation. Biochem Biophys Res Commun 2008; 377:1315-9. [PMID: 19000899 DOI: 10.1016/j.bbrc.2008.10.170] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Accepted: 10/21/2008] [Indexed: 11/16/2022]
Abstract
Glutamate receptor (GluR) delta2 selectively expressed in cerebellar Purkinje cells plays key roles in synapse formation, long-term depression and motor learning. We propose that GluRdelta2 regulates synapse formation by making a physical linkage between the active zone and postsynaptic density. To examine the issue, GluRdelta2-transfected 293T cells were cultured with cerebellar neurons. We found numerous punctate signals for presynaptic markers on the surface of 293T cells expressing GluRdelta2. The presynaptic specializations induced by GluRdelta2 were capable of exo- and endocytosis as indicated by FM1-43 dye labeling. Replacement of the extracellular N-terminal domain (NTD) of GluRdelta2 with that of the AMPA receptor GluRalpha1 abolished the inducing activity. The NTD of GluRdelta2 fused to the immunoglobulin constant region successfully induced the accumulation of presynaptic specializations on the surface of beads bearing the fusion protein. These results suggest that GluRdelta2 triggers presynaptic differentiation by direct interaction with presynaptic components through the NTD.
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Affiliation(s)
- Takeshi Uemura
- Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Enhancement of both long-term depression induction and optokinetic response adaptation in mice lacking delphilin. PLoS One 2008; 3:e2297. [PMID: 18509461 PMCID: PMC2386150 DOI: 10.1371/journal.pone.0002297] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 04/21/2008] [Indexed: 02/06/2023] Open
Abstract
In the cerebellum, Delphilin is expressed selectively in Purkinje cells (PCs) and is localized exclusively at parallel fiber (PF) synapses, where it interacts with glutamate receptor (GluR) delta2 that is essential for long-term depression (LTD), motor learning and cerebellar wiring. Delphilin ablation exerted little effect on the synaptic localization of GluRdelta2. There were no detectable abnormalities in cerebellar histology, PC cytology and PC synapse formation in contrast to GluRdelta2 mutant mice. However, LTD induction was facilitated at PF-PC synapses in Delphilin mutant mice. Intracellular Ca(2+) required for the induction of LTD appeared to be reduced in the mutant mice, while Ca(2+) influx through voltage-gated Ca(2+) channels and metabotropic GluR1-mediated slow synaptic response were similar between wild-type and mutant mice. We further showed that the gain-increase adaptation of the optokinetic response (OKR) was enhanced in the mutant mice. These findings are compatible with the idea that LTD induction at PF-PC synapses is a crucial rate-limiting step in OKR gain-increase adaptation, a simple form of motor learning. As exemplified in this study, enhancing synaptic plasticity at a specific synaptic site of a neural network is a useful approach to understanding the roles of multiple plasticity mechanisms at various cerebellar synapses in motor control and learning.
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Watanabe F, Miyazaki T, Takeuchi T, Fukaya M, Nomura T, Noguchi S, Mori H, Sakimura K, Watanabe M, Mishina M. Effects of FAK ablation on cerebellar foliation, Bergmann glia positioning and climbing fiber territory on Purkinje cells. Eur J Neurosci 2008; 27:836-54. [PMID: 18279360 DOI: 10.1111/j.1460-9568.2008.06069.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that is widely expressed in the brain, and plays key roles in various cellular processes in response to both extracellular and intracellular stimuli. Here, we explored the role of FAK in cerebellar development. In the mouse cerebellum, FAK was found to be distributed as tiny cytoplasmic aggregates in various neuronal and glial elements, including Purkinje cells (PCs), Bergmann glia (BG), parallel fiber (PF)-terminals and climbing fiber (CF)-terminals. The neuron/glia-specific ablation of FAK impaired cerebellar foliation, such as variable decreases in foliation sizes and the lack of intercrural and precentral fissures. Some of the BG cells became situated ectopically in the molecular layer. Furthermore, the FAK ablation altered the innervation territories of CFs and PFs on PCs. CF innervation regressed to the basal portion of proximal dendrites and somata, whereas ectopic spines protruded from proximal dendrites and PFs expanded their territory by innervating the ectopic spines. Furthermore, the persistence of surplus CFs innervating PC somata caused multiple innervation. When FAK was selectively ablated in PCs, diminished dendritic innervation and persistent somatic innervation by CFs were observed, whereas cerebellar foliation and cell positioning of BG were normally retained. These results suggest that FAK in various neuronal and glial elements is required for the formation of normal histoarchitecture and cytoarchitecture in the cerebellum, and for the construction of proper innervation territory and synaptic wiring in PCs.
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Affiliation(s)
- Fumihiro Watanabe
- Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan.
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Yasumura M, Uemura T, Yamasaki M, Sakimura K, Watanabe M, Mishina M. Role of the internal Shank-binding segment of glutamate receptor delta2 in synaptic localization and cerebellar functions. Neurosci Lett 2008; 433:146-51. [PMID: 18249497 DOI: 10.1016/j.neulet.2008.01.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 12/25/2007] [Accepted: 01/03/2008] [Indexed: 10/22/2022]
Abstract
Glutamate receptor (GluR) delta2 selectively expressed in cerebellar Purkinje cells (PCs) plays key roles in cerebellar long-term depression (LTD), motor learning and formation of parallel fiber (PF)-PC synapses. We have recently shown that the PDZ [postsynaptic density (PSD)-95/Discs large/zona occludens-1]-binding domain at the C-terminal, the T site, is essential for LTD induction and the regulation of climbing fiber (CF) territory, but is dispensable for synaptic localization of GluRdelta2, PF-PC synapse formation and CF elimination process. To investigate the functional roles of the S segment, the second PDZ-binding domain in the middle of the C-terminal cytoplasmic region, we generated GluRdelta2DeltaS mice carrying mutant GluRdelta2 lacking this segment. The amount of GluRdelta2DeltaS in mutant mice was reduced compared with that of GluRdelta2 in wild-type mice. However, the extent of decrease was much larger in the PSD fractions than in cerebellar homogenates, suggesting the requirement of the S segment for efficient synaptic localization. Furthermore, mismatched PF synapses and free spines emerged and CF-innervation territory on PC dendrites expanded in GluRdelta2DeltaS mice. On the other hand, the performance in the rotarod test was comparable between wild-type and GluRdelta2DeltaS mice. These results suggest that the S segment and T site, the two PDZ-binding domains in the C-terminal cytoplasmic region, are differentially involved in diverse GluRdelta2 functions.
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Affiliation(s)
- Misato Yasumura
- Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan
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Watanabe M. Molecular Mechanisms Governing Competitive Synaptic Wiring in Cerebellar Purkinje Cells. TOHOKU J EXP MED 2008; 214:175-90. [DOI: 10.1620/tjem.214.175] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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