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Warfield AE, Prather JF, Todd WD. Systems and Circuits Linking Chronic Pain and Circadian Rhythms. Front Neurosci 2021; 15:705173. [PMID: 34276301 PMCID: PMC8284721 DOI: 10.3389/fnins.2021.705173] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 06/10/2021] [Indexed: 12/15/2022] Open
Abstract
Research over the last 20 years regarding the link between circadian rhythms and chronic pain pathology has suggested interconnected mechanisms that are not fully understood. Strong evidence for a bidirectional relationship between circadian function and pain has been revealed through inflammatory and immune studies as well as neuropathic ones. However, one limitation of many of these studies is a focus on only a few molecules or cell types, often within only one region of the brain or spinal cord, rather than systems-level interactions. To address this, our review will examine the circadian system as a whole, from the intracellular genetic machinery that controls its timing mechanism to its input and output circuits, and how chronic pain, whether inflammatory or neuropathic, may mediate or be driven by changes in these processes. We will investigate how rhythms of circadian clock gene expression and behavior, immune cells, cytokines, chemokines, intracellular signaling, and glial cells affect and are affected by chronic pain in animal models and human pathologies. We will also discuss key areas in both circadian rhythms and chronic pain that are sexually dimorphic. Understanding the overlapping mechanisms and complex interplay between pain and circadian mediators, the various nuclei they affect, and how they differ between sexes, will be crucial to move forward in developing treatments for chronic pain and for determining how and when they will achieve their maximum efficacy.
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Affiliation(s)
| | | | - William D. Todd
- Program in Neuroscience, Department of Zoology and Physiology, University of Wyoming, Laramie, WY, United States
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2
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Cherra SJ, Goncharov A, Boassa D, Ellisman M, Jin Y. C. elegans MAGU-2/Mpp5 homolog regulates epidermal phagocytosis and synapse density. J Neurogenet 2020; 34:298-306. [PMID: 32366143 DOI: 10.1080/01677063.2020.1726915] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Synapses are dynamic connections that underlie essential functions of the nervous system. The addition, removal, and maintenance of synapses govern the flow of information in neural circuits throughout the lifetime of an animal. While extensive studies have elucidated many intrinsic mechanisms that neurons employ to modulate their connections, increasing evidence supports the roles of non-neuronal cells, such as glia, in synapse maintenance and circuit function. We previously showed that C. elegans epidermis regulates synapses through ZIG-10, a cell-adhesion protein of the immunoglobulin domain superfamily. Here we identified a member of the Pals1/MPP5 family, MAGU-2, that functions in the epidermis to modulate phagocytosis and the number of synapses by regulating ZIG-10 localization. Furthermore, we used light and electron microscopy to show that this epidermal mechanism removes neuronal membranes from the neuromuscular junction, dependent on the conserved phagocytic receptor CED-1. Together, our study shows that C. elegans epidermis constrains synaptic connectivity, in a manner similar to astrocytes and microglia in mammals, allowing optimized output of neural circuits.
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Affiliation(s)
- Salvatore J Cherra
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA.,Department of Neuroscience, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Alexandr Goncharov
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Daniela Boassa
- National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, CA, USA
| | - Mark Ellisman
- National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, CA, USA.,Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA.,Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, USA.,Department of Cellular and Molecular Medicine, School of Medicine, University of California San Diego, La Jolla, CA, USA
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3
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Abarzúa S, Ampuero E, Zundert B. Superoxide generation via the NR2B‐NMDAR/RasGRF1/NOX2 pathway promotes dendritogenesis. J Cell Physiol 2019; 234:22985-22995. [DOI: 10.1002/jcp.28859] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 05/03/2019] [Accepted: 05/03/2019] [Indexed: 12/13/2022]
Affiliation(s)
- Sebastian Abarzúa
- Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de la Ciencias de la Vida Universidad Andres Bello Santiago Chile
- Centro de Envejecimiento y Regeneración CARE Chile UC Santiago Chile
| | - Estibaliz Ampuero
- Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de la Ciencias de la Vida Universidad Andres Bello Santiago Chile
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud Universidad Autónoma de Chile Santiago Chile
| | - Brigitte Zundert
- Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de la Ciencias de la Vida Universidad Andres Bello Santiago Chile
- Centro de Envejecimiento y Regeneración CARE Chile UC Santiago Chile
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4
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Abstract
Cerebral organoids are an emerging cutting-edge technology to model human brain
development and neurodevelopmental disorders, for which mouse models exhibit significant
limitations. In the human brain, synaptic connections define neural circuits, and synaptic
deficits account for various neurodevelopmental disorders. Thus, harnessing the full power
of cerebral organoids for human brain modeling requires the ability to visualize and
analyze synapses in cerebral organoids. Previously, we devised an optimized method to
generate human cerebral organoids, and showed that optimal organoids express mature-neuron
markers, including synaptic proteins and neurotransmitter receptors and transporters.
Here, we give evidence for synaptogenesis in cerebral organoids, via microscopical
visualization of synapses. We also describe multiple approaches to quantitatively analyze
synapses in cerebral organoids. Collectively, our work provides sufficient evidence for
the possibility of modeling synaptogenesis and synaptic disorders in cerebral organoids,
and may help advance the use of cerebral organoids in molecular neuroscience and studies
of neurodevelopmental disorders such as autism.
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Affiliation(s)
- Abraam M Yakoub
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Mark Sadek
- Department of Pharmaceutical Biotechnology, University of Illinois College of Pharmacy, Chicago, IL, USA.,Department of Research and Development, Akorn Pharmaceuticals, Vernon Hills, IL, USA
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5
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Metabotropic functions of the NMDA receptor and an evolving rationale for exploring NR2A-selective positive allosteric modulators for the treatment of autism spectrum disorder. Prog Neuropsychopharmacol Biol Psychiatry 2019; 90:142-160. [PMID: 30481555 DOI: 10.1016/j.pnpbp.2018.11.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 11/19/2018] [Accepted: 11/22/2018] [Indexed: 12/18/2022]
Abstract
NMDA receptors are widely distributed throughout the brain and major therapeutic challenges include targeting specific NMDA receptor subtypes while preserving spatial and temporal specificity during their activation. The NR2A-subunit containing NMDA receptor is implicated in regulating synchronous oscillatory output of cortical pyramidal neurons, which may be disturbed in clinical presentations of autism spectrum disorder (ASD). Because NR2A-selective positive allosteric modulators (PAMs) preserve spatial and temporal selectivity while activating this subpopulation of receptors, they represent a promising strategy to address neocortical circuit abnormalities in ASD. In addition to promoting Ca2+ entry and membrane depolarization, diverse metabotropic effects of NMDA receptor activation on signal transduction pathways occur within the cell, some of which depend on alignment of protein binding partners. For example, NMDA receptor agonist interventions attenuate impaired sociability in transgenic mice with 'loss-of-function' mutations of the Shank family of scaffolding proteins, which highlights the necessity of a carefully orchestrated alignment of protein binding partners in the excitatory synapse. The current Review considers metabotropic functions of the NMDA receptor that could play a role in sociability and the pathogenesis of ASD (e.g., mTOR signaling), in addition to its more familiar ionotropic functions, and provides a rationale for therapeutic exploration of NR2A-selective PAMs.
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6
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Bustos FJ, Jury N, Martinez P, Ampuero E, Campos M, Abarzúa S, Jaramillo K, Ibing S, Mardones MD, Haensgen H, Kzhyshkowska J, Tevy MF, Neve R, Sanhueza M, Varela-Nallar L, Montecino M, van Zundert B. NMDA receptor subunit composition controls dendritogenesis of hippocampal neurons through CAMKII, CREB-P, and H3K27ac. J Cell Physiol 2017; 232:3677-3692. [PMID: 28160495 DOI: 10.1002/jcp.25843] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 02/03/2017] [Indexed: 12/29/2022]
Abstract
Dendrite arbor growth, or dendritogenesis, is choreographed by a diverse set of cues, including the NMDA receptor (NMDAR) subunits NR2A and NR2B. While NR1NR2B receptors are predominantly expressed in immature neurons and promote plasticity, NR1NR2A receptors are mainly expressed in mature neurons and induce circuit stability. How the different subunits regulate these processes is unclear, but this is likely related to the presence of their distinct C-terminal sequences that couple different signaling proteins. Calcium-calmodulin-dependent protein kinase II (CaMKII) is an interesting candidate as this protein can be activated by calcium influx through NMDARs. CaMKII triggers a series of biochemical signaling cascades, involving the phosphorylation of diverse targets. Among them, the activation of cAMP response element-binding protein (CREB-P) pathway triggers a plasticity-specific transcriptional program through unknown epigenetic mechanisms. Here, we found that dendritogenesis in hippocampal neurons is impaired by several well-characterized constructs (i.e., NR2B-RS/QD) and peptides (i.e., tatCN21) that specifically interfere with the recruitment and interaction of CaMKII with the NR2B C-terminal domain. Interestingly, we found that transduction of NR2AΔIN, a mutant NR2A construct with increased interaction to CaMKII, reactivates dendritogenesis in mature hippocampal neurons in vitro and in vivo. To gain insights into the signaling and epigenetic mechanisms underlying NMDAR-mediated dendritogenesis, we used immunofluorescence staining to detect CREB-P and acetylated lysine 27 of histone H3 (H3K27ac), an activation-associated histone tail mark. In contrast to control mature neurons, our data shows that activation of the NMDAR/CaMKII/ERK-P/CREB-P signaling axis in neurons expressing NR2AΔIN is not correlated with increased nuclear H3K27ac levels.
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Affiliation(s)
- Fernando J Bustos
- Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Santiago, Chile
- FONDAP Center for Genome Regulation, Santiago, Chile
| | - Nur Jury
- Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Santiago, Chile
| | - Pablo Martinez
- Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Santiago, Chile
| | - Estibaliz Ampuero
- Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Santiago, Chile
| | - Matias Campos
- Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Santiago, Chile
| | - Sebastian Abarzúa
- Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Santiago, Chile
| | - Karen Jaramillo
- Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Santiago, Chile
- FONDAP Center for Genome Regulation, Santiago, Chile
| | - Susanne Ibing
- Institute of Transfusion Medicine and Immunology, Medical Faculty Mannheim, University of Heidelberg, German Red Cross Blood Service Baden-Württemberg-Hessen, Mannheim, Germany
| | - Muriel D Mardones
- Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Santiago, Chile
| | - Henny Haensgen
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Julia Kzhyshkowska
- Institute of Transfusion Medicine and Immunology, Medical Faculty Mannheim, University of Heidelberg, German Red Cross Blood Service Baden-Württemberg-Hessen, Mannheim, Germany
| | - Maria Florencia Tevy
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Rachael Neve
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Magdalena Sanhueza
- Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Lorena Varela-Nallar
- Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Santiago, Chile
| | - Martín Montecino
- Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Santiago, Chile
- FONDAP Center for Genome Regulation, Santiago, Chile
| | - Brigitte van Zundert
- Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Santiago, Chile
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7
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Shen Y, Xu L, Liu M, Lei Y, Gu X, Ma Z. The effects of an intraperitoneal single low dose of ketamine in attenuating the postoperative skin/muscle incision and retraction-induced pain related to the inhibition of N-methyl-d-aspartate receptors in the spinal cord. Neurosci Lett 2016; 616:211-7. [DOI: 10.1016/j.neulet.2015.12.045] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Revised: 11/18/2015] [Accepted: 12/17/2015] [Indexed: 10/22/2022]
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8
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Bats C, Farrant M, Cull-Candy SG. A role of TARPs in the expression and plasticity of calcium-permeable AMPARs: evidence from cerebellar neurons and glia. Neuropharmacology 2013; 74:76-85. [PMID: 23583927 PMCID: PMC3751754 DOI: 10.1016/j.neuropharm.2013.03.037] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/21/2013] [Accepted: 03/28/2013] [Indexed: 02/04/2023]
Abstract
The inclusion of GluA2 subunits has a profound impact on the channel properties of AMPA receptors (AMPARs), in particular rendering them impermeable to calcium. While GluA2-containing AMPARs are the most abundant in the central nervous system, GluA2-lacking calcium-permeable AMPARs are also expressed in wide variety of neurons and glia. Accumulating evidence suggests that the dynamic control of the GluA2 content of AMPARs plays a critical role in development, synaptic plasticity, and diverse neurological conditions ranging from ischemia-induced brain damage to drug addiction. It is thus important to understand the molecular mechanisms involved in regulating the balance of AMPAR subtypes, particularly the role of their co-assembled auxiliary subunits. The discovery of transmembrane AMPAR regulatory proteins (TARPs), initially within the cerebellum, has transformed the field of AMPAR research. It is now clear that these auxiliary subunits play a key role in multiple aspects of AMPAR trafficking and function in the brain. Yet, their precise role in AMPAR subtype-specific regulation has only recently received particular attention. Here we review recent findings on the differential regulation of calcium-permeable (CP-) and -impermeable (CI-) AMPARs in cerebellar neurons and glial cells, and discuss the critical involvement of TARPs in this process. This article is part of the Special Issue entitled ‘Glutamate Receptor-Dependent Synaptic Plasticity’. Calcium-permeable AMPARs are present in various cerebellar neurons and glial cells. The contribution of calcium-permeable AMPARs to transmission is dynamically regulated. TARPs influence the relative expression of AMPAR subtypes. Evidence suggests that TARPs play a role in calcium-permeable AMPAR plasticity.
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Affiliation(s)
- Cécile Bats
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
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9
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AMPA receptor/TARP stoichiometry visualized by single-molecule subunit counting. Proc Natl Acad Sci U S A 2013; 110:5163-8. [PMID: 23479622 DOI: 10.1073/pnas.1218765110] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Members of the transmembrane AMPA receptor-regulatory protein (TARP) family modulate AMPA receptor (AMPA-R) trafficking and function. AMPA-Rs consist of four pore-forming subunits. Previous studies show that TARPs are an integral part of the AMPA-R complex, acting as accessory subunits for mature receptors in vivo. The TARP/AMPA-R stoichiometry was previously measured indirectly and found to be variable and dependent on TARP expression level, with at most four TARPs associated with each AMPA-R complex. Here, we use a single-molecule technique in live cells that selectively images proteins located in the plasma membrane to directly count the number of TARPs associated with each AMPA-R complex. Although individual GFP-tagged TARP subunits are observed as freely diffusing fluorescent spots on the surface of Xenopus laevis oocytes when expressed alone, coexpression with AMPA-R-mCherry immobilizes the stargazin-GFP spots at sites of AMPA-R-mCherry, consistent with complex formation. We determined the number of TARP molecules associated with each AMPA-R by counting bleaching steps for three different TARP family members: γ-2, γ-3, and γ-4. We confirm that the TARP/AMPA-R stoichiometry depends on TARP expression level and discover that the maximum number of TARPs per AMPA-R complex falls into two categories: up to four γ-2 or γ-3 subunits, but rarely above two for γ-4 subunit. This unexpected AMPA-R/TARP stoichiometry difference has important implications for the assembly and function of TARP/AMPA-R complexes.
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10
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Enhanced NMDA receptor-dependent thalamic excitation and network oscillations in stargazer mice. J Neurosci 2012; 32:11067-81. [PMID: 22875939 DOI: 10.1523/jneurosci.5604-11.2012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Disturbances in corticothalamic circuitry can lead to absence epilepsy. The reticular thalamic nucleus (RTN) plays a pivotal role in that it receives excitation from cortex and thalamus and, when strongly activated, can generate excessive inhibitory output and epileptic thalamocortical oscillations that depend on postinhibitory rebound. Stargazer (stg) mice have prominent absence seizures resulting from a mutant form of the AMPAR auxiliary protein stargazin. Reduced AMPAR excitation in RTN has been demonstrated previously in stg, yet the mechanisms leading from RTN hypoexcitation to epilepsy are unknown and unexpected because thalamic epileptiform oscillatory activity requires AMPARs. We demonstrate hyperexcitability in stg thalamic slices and further characterize the various excitatory inputs to RTN using electrical stimulation and laser scanning photostimulation. Patch-clamp recordings of spontaneous and evoked EPSCs in RTN neurons demonstrate reduced amplitude and increased duration of the AMPAR component with an increased amplitude NMDAR component. Short 200 Hz stimulus trains evoked a gradual approximately threefold increase in NMDAR EPSCs compared with single stimuli in wild-type (WT), indicating progressive NMDAR recruitment, whereas in stg cells, NMDAR responses were nearly maximal with single stimuli. Array tomography revealed lower synaptic, but higher perisynaptic, AMPAR density in stg RTN. Increasing NMDAR activity via reduced [Mg2+]o in WT phenocopied the thalamic hyperexcitability observed in stg, whereas changing [Mg2+]o had no effect on stg slices. These findings suggest that, in stg, a trafficking defect in synaptic AMPARs in RTN cells leads to a compensatory increase in synaptic NMDARs and enhanced thalamic excitability.
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Strauss J, McGregor S, Freeman N, Tiwari A, George CJ, Kovacs M, Kennedy JL. Association study of early-immediate genes in childhood-onset mood disorders and suicide attempt. Psychiatry Res 2012; 197:49-54. [PMID: 22460132 PMCID: PMC3376203 DOI: 10.1016/j.psychres.2011.11.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Revised: 11/06/2011] [Accepted: 11/26/2011] [Indexed: 01/17/2023]
Abstract
Childhood-onset mood disorders (COMD) are serious affective disorders with deleterious developmental sequelae including interpersonal dysfunction, psychotic symptoms and suicidal behavior. The current study examines 10 markers from two early-immediate genes for association with COMD and suicide attempt (SA) - HOMER1 and human neuronal pentraxin II (NPTX2). We examined individuals diagnosed with COMD versus matched controls, as well as individuals with COMD and a history of at least one lifetime SA versus COMD participants with no history of SA. No significant genotypic association was noted between any of the single nucleotide polymorphisms (SNPs) and COMD. Our sample yielded a nominally significant allelic association between the HOMER1 rs7713917 SNP and COMD. We report significant genotype associations between HOMER1 rs2290639 and SA , and between NPTX2 markers rs705315 and rs1681248 and SA, findings that remained statistically significant after multiple test correction. A three-way interaction was observed among HOMER1 rs4704560, rs2290639 and NPTX2 rs705318. The associations we describe for HOMER1 and NPTX2 with SA should be considered preliminary until replicated.
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Affiliation(s)
- John Strauss
- Centre for Addiction and Mental Health, University of Toronto, Toronto, ON, Canada.
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12
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Bard L, Groc L. Glutamate receptor dynamics and protein interaction: lessons from the NMDA receptor. Mol Cell Neurosci 2011; 48:298-307. [PMID: 21640188 DOI: 10.1016/j.mcn.2011.05.009] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Revised: 05/17/2011] [Accepted: 05/18/2011] [Indexed: 11/16/2022] Open
Abstract
The plasticity of excitatory glutamate synapses emerged over the last decades as a core cellular mechanism for the encoding and processing of various cognitive functions. This property relies in part on the ability to dynamically adjust the content of glutamate receptors in the postsynaptic membrane. Among these receptors, NMDA receptors (NMDAR), which are composed of two obligatory GluN1 and two regulatory GluN2/3 subunits, play a key role in the induction of many forms of plasticity processes. Understanding how NMDAR subtypes are trafficked and regulated in the synapse has thus captured considerable attention. It has emerged that NMDAR synaptic content relies on an equilibrium between intracellular trafficking and rapid lateral diffusion of the receptor within the synaptic area. Here, we review our current understanding of NMDAR trafficking, mostly the ones at the surface membrane, with a specific focus on the role of interacting PDZ-containing proteins during the journey of NMDAR to and around the synaptic area. The cellular and molecular lessons obtained from examining NMDAR dynamics and regulation by interacting proteins appear to apply to other ionotropic neurotransmitter receptors, and thus shed new light on the modulation of excitatory, inhibitory, and modulatory transmission. This article is part of a Special Issue entitled 'Neuronal Function'.
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Affiliation(s)
- Lucie Bard
- Univ. de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France
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13
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Moghekar A, Rao S, Li M, Ruben D, Mammen A, Tang X, O'Brien RJ. Large quantities of Abeta peptide are constitutively released during amyloid precursor protein metabolism in vivo and in vitro. J Biol Chem 2011; 286:15989-97. [PMID: 21454701 DOI: 10.1074/jbc.m110.191262] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The metabolism of the amyloid precursor protein (APP) has been extensively investigated because its processing generates the amyloid-β-peptide (Aβ), which is a likely cause of Alzheimer disease. Much prior research has focused on APP processing using transgenic constructs and heterologous cell lines. Work to date in native neuronal cultures suggests that Aβ is produced in very large amounts. We sought to investigate APP metabolism and Aβ production simultaneously under more physiological conditions in vivo and in vitro using cultured rat cortical neurons and live pigs. We found in cultured neurons that both APP and Aβ are secreted rapidly and at extremely high rates into the extracellular space (2-4 molecules/neuron/s for Aβ). Little APP is degraded outside of the pathway that leads to extracellular release. Two metabolic pools of APP are identified, one that is metabolized extremely rapidly (t1/2;) = 2.2 h), and another, surface pool, composed of both synaptic and extrasynaptic elements, that turns over very slowly. Aβ release and accumulation in the extracellular medium can be accounted for stoichiometrically by the extracellular release of β-cleaved forms of the APP ectodomain. Two α-cleavages of APP occur for every β-cleavage. Consistent with the results seen in cultured neurons, an extremely high rate of Aβ production and secretion from the brain was seen in juvenile pigs. In summary, our experiments show an enormous and rapid production and extracellular release of Aβ and the soluble APP ectodomain. A small, slowly metabolized, surface pool of full-length APP is also identified.
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Affiliation(s)
- Abhay Moghekar
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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14
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Hamdan F, Gauthier J, Araki Y, Lin DT, Yoshizawa Y, Higashi K, Park AR, Spiegelman D, Dobrzeniecka S, Piton A, Tomitori H, Daoud H, Massicotte C, Henrion E, Diallo O, Shekarabi M, Marineau C, Shevell M, Maranda B, Mitchell G, Nadeau A, D'Anjou G, Vanasse M, Srour M, Lafrenière R, Drapeau P, Lacaille J, Kim E, Lee JR, Igarashi K, Huganir R, Rouleau G, Michaud J, Michaud JL. Excess of de novo deleterious mutations in genes associated with glutamatergic systems in nonsyndromic intellectual disability. Am J Hum Genet 2011; 88:306-16. [PMID: 21376300 DOI: 10.1016/j.ajhg.2011.02.001] [Citation(s) in RCA: 267] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 01/27/2011] [Accepted: 02/01/2011] [Indexed: 10/18/2022] Open
Abstract
Little is known about the genetics of nonsyndromic intellectual disability (NSID). We hypothesized that de novo mutations (DNMs) in synaptic genes explain an important fraction of sporadic NSID cases. In order to investigate this possibility, we sequenced 197 genes encoding glutamate receptors and a large subset of their known interacting proteins in 95 sporadic cases of NSID. We found 11 DNMs, including ten potentially deleterious mutations (three nonsense, two splicing, one frameshift, four missense) and one neutral mutation (silent) in eight different genes. Calculation of point-substitution DNM rates per functional and neutral site showed significant excess of functional DNMs compared to neutral ones. De novo truncating and/or splicing mutations in SYNGAP1, STXBP1, and SHANK3 were found in six patients and are likely to be pathogenic. De novo missense mutations were found in KIF1A, GRIN1, CACNG2, and EPB41L1. Functional studies showed that all these missense mutations affect protein function in cell culture systems, suggesting that they may be pathogenic. Sequencing these four genes in 50 additional sporadic cases of NSID identified a second DNM in GRIN1 (c.1679_1681dup/p.Ser560dup). This mutation also affects protein function, consistent with structural predictions. None of these mutations or any other DNMs were identified in these genes in 285 healthy controls. This study highlights the importance of the glutamate receptor complexes in NSID and further supports the role of DNMs in this disorder.
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15
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Yu L, Rostamiani K, Hsu YT, Wang Y, Bi X, Baudry M. Calpain-mediated regulation of stargazin in adult rat brain. Neuroscience 2011; 178:13-20. [PMID: 21256931 DOI: 10.1016/j.neuroscience.2011.01.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 01/14/2011] [Indexed: 11/29/2022]
Abstract
Changes in AMPA receptors have been proposed to underlie changes in synaptic efficacy in hippocampus and other brain structures. Calpain activation has also been discussed as a potential mechanism to produce lasting modifications of synaptic structure and function. Stargazin is a member of the family of transmembrane AMPA receptor associated proteins (TARPs), which participates in trafficking of AMPA receptors and regulates their kinetic properties. We report here that preincubation of thin (20 μm) frozen rat brain sections with calcium changes the immunological properties of stargazin, an effect totally blocked by a calpain inhibitor. Immunocytochemistry indicates that in situ calpain activation produces a decreased immunoreactivity for stargazin in the neuropil throughout the brain, and Western blots confirmed that a similar treatment decreased stargazin levels. Interestingly, the same treatment did not modify the immunoreactivity for another TARP member, γ-8, although it increased immunoreactivity in cell bodies in hippocampus, an effect that was not blocked by calpain inhibition. These results strongly suggest the involvement of calpain in the regulation of AMPA receptor targeting and function through truncation of stargazin.
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Affiliation(s)
- L Yu
- Neuroscience Program, University of Southern California, Los Angeles, CA 90089-2520, USA
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16
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Sepulveda FJ, Bustos FJ, Inostroza E, Zúñiga FA, Neve RL, Montecino M, van Zundert B. Differential roles of NMDA Receptor Subtypes NR2A and NR2B in dendritic branch development and requirement of RasGRF1. J Neurophysiol 2010; 103:1758-70. [PMID: 20107120 DOI: 10.1152/jn.00823.2009] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
N-methyl-D-aspartate receptors (NMDARs) are known to regulate axonal refinement and dendritic branching. However, because NMDARs are abundantly present as tri-heteromers (e.g., NR1/NR2A/NR2B) during development, the precise role of the individual subunits NR2A and NR2B in these processes has not been elucidated. Ventral spinal cord neurons (VSCNs) provide a unique opportunity to address this problem, because the expression of both NR2A and NR2B (but not NR1) is downregulated in culture. Exogenous NR2A or NR2B were introduced into these naturally NR2-null neurons at 4 DIV, and electrophysiological recordings at 11 DIV confirmed that synaptic NR1NR2A receptors and NR1NR2B receptors were formed, respectively. Analysis of the dendritic architecture showed that introduction of NR2B, but not NR2A, dramatically increased the number of secondary and tertiary dendritic branches of VSCNs. Whole cell patch-clamp recordings further indicated that the newly formed branches in NR2B-expressing neurons were able to establish functional synapses because the frequency of miniature AMPA-receptor synaptic currents was increased. Using previously described mutants, we also found that disruption of the interaction between NR2B and RasGRF1 dramatically impaired dendritic branch formation in VSCNs. The differential role of the NR2A and NR2B subunits and the requirement for RasGRF1 in regulating branch formation was corroborated in hippocampal cultures. We conclude that the association between NR1NR2B-receptors and RasGRF1 is needed for dendritic branch formation in VSCNs and hippocampal neurons in vitro. The dominated NR2A expression and the limited interactions of this subunit with the signaling protein RasGRF1 may contribute to the restricted dendritic arbor development in the adult CNS.
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Affiliation(s)
- Fernando J Sepulveda
- Dept. of Physiopathology, Faculty of Biological Sciences, Univ. of Concepción, Concepción, Chile
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Central sensitization: a generator of pain hypersensitivity by central neural plasticity. THE JOURNAL OF PAIN 2009; 10:895-926. [PMID: 19712899 DOI: 10.1016/j.jpain.2009.06.012] [Citation(s) in RCA: 2280] [Impact Index Per Article: 152.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Revised: 06/08/2009] [Accepted: 06/08/2009] [Indexed: 02/08/2023]
Abstract
UNLABELLED Central sensitization represents an enhancement in the function of neurons and circuits in nociceptive pathways caused by increases in membrane excitability and synaptic efficacy as well as to reduced inhibition and is a manifestation of the remarkable plasticity of the somatosensory nervous system in response to activity, inflammation, and neural injury. The net effect of central sensitization is to recruit previously subthreshold synaptic inputs to nociceptive neurons, generating an increased or augmented action potential output: a state of facilitation, potentiation, augmentation, or amplification. Central sensitization is responsible for many of the temporal, spatial, and threshold changes in pain sensibility in acute and chronic clinical pain settings and exemplifies the fundamental contribution of the central nervous system to the generation of pain hypersensitivity. Because central sensitization results from changes in the properties of neurons in the central nervous system, the pain is no longer coupled, as acute nociceptive pain is, to the presence, intensity, or duration of noxious peripheral stimuli. Instead, central sensitization produces pain hypersensitivity by changing the sensory response elicited by normal inputs, including those that usually evoke innocuous sensations. PERSPECTIVE In this article, we review the major triggers that initiate and maintain central sensitization in healthy individuals in response to nociceptor input and in patients with inflammatory and neuropathic pain, emphasizing the fundamental contribution and multiple mechanisms of synaptic plasticity caused by changes in the density, nature, and properties of ionotropic and metabotropic glutamate receptors.
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18
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NS21: re-defined and modified supplement B27 for neuronal cultures. J Neurosci Methods 2008; 171:239-47. [PMID: 18471889 PMCID: PMC2678682 DOI: 10.1016/j.jneumeth.2008.03.013] [Citation(s) in RCA: 225] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2007] [Revised: 03/23/2008] [Accepted: 03/24/2008] [Indexed: 11/24/2022]
Abstract
In vitro culturing of primary neurons is a mainstay of neurobiological research. Many of these culture paradigms have taken advantage of defined culture media rather than serum additives that contain undefined survival factors to facilitate experimental manipulations and interpretation of the results. To culture neurons in the absence of serum, defined supplements such as B27 are now widely used. However, commercially available supplements exhibit large variability in their capabilities to support neurons in culture. We re-optimized and modified earlier published formulations of B27 using 21 different ingredients (NS21). NS21 supports neuronal cultures of high quality as manifested by their morphological characteristics, formation of synapses, and postsynaptic responses. Much of the variability in the quality of B27/NS21 was due to variability in the quality of different sources of bovine serum albumin. Furthermore, we found that holo-transferrin used in NS21 is preferable over apo-transferrin used in B27 for the quality of neuronal cultures.
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Cousins SL, Papadakis M, Rutter AR, Stephenson FA. Differential interaction of NMDA receptor subtypes with the post-synaptic density-95 family of membrane associated guanylate kinase proteins. J Neurochem 2008; 104:903-13. [PMID: 18233995 DOI: 10.1111/j.1471-4159.2007.05067.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
NMDA receptors are a subclass of ionotropic glutamate receptors. They are trafficked and/or clustered at synapses by the post-synaptic density (PSD)-95 membrane associated guanylate kinase (MAGUK) family of scaffolding proteins that associate with NMDA receptor NR2 subunits via their C-terminal glutamate serine (aspartate/glutamate) valine motifs. We have carried out a systematic study investigating in a heterologous expression system, the association of the four major NMDA receptor subtypes with the PSD-95 family of MAGUK proteins, chapsyn-110, PSD-95, synapse associated protein (SAP) 97 and SAP102. We report that although each PSD-95 MAGUK was shown to co-immunoprecipitate with NR1/NR2A, NR1/NR2B, NR1/NR2C and NR1/NR2D receptor subtypes, they elicited differential effects with regard to the enhancement of total NR2 subunit expression which then results in an increased cell surface expression of NMDA receptor subtypes. PSD-95 and chapsyn-110 enhanced NR2A and NR2B total expression which resulted in increased NR1/NR2A and NR1/NR2B receptor cell surface expression whereas SAP97 and SAP102 had no effect on total or cell surface expression of these subtypes. PSD-95, chapsyn-110, SAP97 and SAP102 had no effect on either total NR2C and NR2D subunit expression or cell surface NR1/NR2C and NR1/NR2D expression. A comparison of PSD-95alpha, PSD-95beta and PSD-95alpha(C3S,C5S) showed that PSD-95-enhanced cell surface expression of NR1/NR2A receptors was dependent upon the PSD-95 N-terminal C3,C5 cysteines. These observations support differential interaction of NMDA receptor subtypes with different PSD-95 MAGUK scaffolding proteins. This has implications for the stabilisation, turnover and compartmentalisation of NMDA receptor subtypes in neurones during development and in the mature brain.
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20
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Rohrbough J, Rushton E, Woodruff E, Fergestad T, Vigneswaran K, Broadie K. Presynaptic establishment of the synaptic cleft extracellular matrix is required for post-synaptic differentiation. Genes Dev 2007; 21:2607-28. [PMID: 17901219 PMCID: PMC2000325 DOI: 10.1101/gad.1574107] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Formation and regulation of excitatory glutamatergic synapses is essential for shaping neural circuits throughout development. In a Drosophila genetic screen for synaptogenesis mutants, we identified mind the gap (mtg), which encodes a secreted, extracellular N-glycosaminoglycan-binding protein. MTG is expressed neuronally and detected in the synaptic cleft, and is required to form the specialized transsynaptic matrix that links the presynaptic active zone with the post-synaptic glutamate receptor (GluR) domain. Null mtg embryonic mutant synapses exhibit greatly reduced GluR function, and a corresponding loss of localized GluR domains. All known post-synaptic signaling/scaffold proteins functioning upstream of GluR localization are also grossly reduced or mislocalized in mtg mutants, including the dPix-dPak-Dock cascade and the Dlg/PSD-95 scaffold. Ubiquitous or neuronally targeted mtg RNA interference (RNAi) similarly reduce post-synaptic assembly, whereas post-synaptically targeted RNAi has no effect, indicating that presynaptic MTG induces and maintains the post-synaptic pathways driving GluR domain formation. These findings suggest that MTG is secreted from the presynaptic terminal to shape the extracellular synaptic cleft domain, and that the cleft domain functions to mediate transsynaptic signals required for post-synaptic development.
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Affiliation(s)
- Jeffrey Rohrbough
- Department of Biological Sciences, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Emma Rushton
- Department of Biological Sciences, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Elvin Woodruff
- Department of Biological Sciences, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Tim Fergestad
- Department of Biological Sciences, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Krishanthan Vigneswaran
- Department of Biological Sciences, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Kendal Broadie
- Department of Biological Sciences, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37235, USA
- Corresponding author.E-MAIL ; FAX (615) 936-0129
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21
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Abstract
AMPA receptors (AMPARs) conduct fast, excitatory currents that depolarize neurons and trigger action potentials. AMPARs took on new importance when it was shown that AMPAR transport can increase or decrease the number of AMPARs at synapses and give rise to synapse plasticity, including long-term potentiation (LTP) and long-term depression (LTD). This review considers how transmembrane AMPAR regulatory proteins (TARPs), a novel family of AMPAR auxiliary subunits, have changed our view of AMPAR transport and raised some perplexing questions.
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Affiliation(s)
- Edward B Ziff
- Department of Biochemistry, New York University School of Medicine, New York, NY 10016, USA.
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22
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Rosen KM, Moghekar A, O’Brien RJ. Activity dependent localization of synaptic NMDA receptors in spinal neurons. Mol Cell Neurosci 2006; 34:578-91. [PMID: 17306986 PMCID: PMC2735016 DOI: 10.1016/j.mcn.2006.12.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2006] [Revised: 11/25/2006] [Accepted: 12/21/2006] [Indexed: 11/24/2022] Open
Abstract
In cultured spinal neurons, NMDA receptors are absent from excitatory synapses under basal conditions, but can be made to appear at excitatory synapses following blockade of excitatory synaptic activity. The activity dependent synaptic localization of NMDA receptors is critically dependent on both the gradual, global accumulation of the NR2A and NR2B subunits and on a rapid, surface redistribution phase that is primed by the accumulation of NR2A and NR2B and inhibited by synaptic activity. Global changes in NR2A and NR2B accumulation and heterogeneous increases in synaptic NMDA receptor localization can also result from inhibitors of proteasomal processing, from manipulations of proteasomal subunit composition and from media conditioned by neurons undergoing synaptic scaling. While proteasomal processing is a mechanism shared with AMPA receptor scaling in cultured spinal neurons, diffusible factors, heterogeneity, and a rapid surface redistribution phase appear to be unique to activity dependent synaptic NMDA receptor localization.
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Affiliation(s)
- Kenneth M Rosen
- Department of Neurology, Caritas St. Elizabeth’s Medical Center, Tufts University School of Medicine, Boston, MA 02135
| | - Abhay Moghekar
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205
| | - Richard J O’Brien
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205
- Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205
- Address Correspondence to: Richard J O’Brien MD, Mason F Lord Center Tower Room 5100, Johns Hopkins Bayview Medical Center, 5200 Eastern Ave, Baltimore, MD 21224, Ph: 410 550 8703, Fax: 410 550 8715,
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23
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Deng F, Price MG, Davis CF, Mori M, Burgess DL. Stargazin and other transmembrane AMPA receptor regulating proteins interact with synaptic scaffolding protein MAGI-2 in brain. J Neurosci 2006; 26:7875-84. [PMID: 16870733 PMCID: PMC6674230 DOI: 10.1523/jneurosci.1851-06.2006] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The spatial coordination of neurotransmitter receptors with other postsynaptic signaling and structural molecules is regulated by a diverse array of cell-specific scaffolding proteins. The synaptic trafficking of AMPA receptors by the stargazin protein in some neurons, for example, depends on specific interactions between the C terminus of stargazin and the PDZ [postsynaptic density-95 (PSD-95)/Discs large/zona occludens-1] domains of membrane-associated guanylate kinase scaffolding proteins PSD-93 or PSD-95. Stargazin [Cacng2 (Ca2+ channel gamma2 subunit)] is one of four closely related proteins recently categorized as transmembrane AMPA receptor regulating proteins (TARPs) that appear to share similar functions but exhibit distinct expression patterns in the CNS. We used yeast two-hybrid screening to identify MAGI-2 (membrane associated guanylate kinase, WW and PDZ domain containing 2) as a novel candidate interactor with the cytoplasmic C termini of the TARPs. MAGI-2 [also known as S-SCAM (synaptic scaffolding molecule)] is a multi-PDZ domain scaffolding protein that interacts with several different ligands in brain, including PTEN (phosphatase and tensin homolog), dasm1 (dendrite arborization and synapse maturation 1), dendrin, axin, beta- and delta-catenin, neuroligin, hyperpolarization-activated cation channels, beta1-adrenergic receptors, and NMDA receptors. We confirmed that MAGI-2 coimmunoprecipitated with stargazin in vivo from mouse cerebral cortex and used in vitro assays to localize the interaction to the C-terminal -TTPV amino acid motif of stargazin and the PDZ1, PDZ3, and PDZ5 domains of MAGI-2. Expression of stargazin recruited MAGI-2 to cell membranes and cell-cell contact sites in transfected HEK-293T cells dependent on the presence of the stargazin -TTPV motif. These experiments identify MAGI-2 as a strong candidate for linking TARP/AMPA receptor complexes to a wide range of other postsynaptic molecules and pathways and advance our knowledge of protein interactions at mammalian CNS synapses.
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24
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Zhang X, Bao L. The development and modulation of nociceptive circuitry. Curr Opin Neurobiol 2006; 16:460-6. [PMID: 16828278 DOI: 10.1016/j.conb.2006.06.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Accepted: 06/26/2006] [Indexed: 12/21/2022]
Abstract
Nociceptive circuitry processes the signals evoked by activating specialized peripheral sensory receptors for pain perception. Recent studies show that the neuronal phenotypes in the dorsal root ganglia and spinal dorsal horn are determined by distinct sets of transcription factors during development. Anatomical analyses with genetic approaches demonstrate that each subset of nociceptive sensory neurons has topographically distinct circuits at both spinal and brain levels. Moreover, the sensitivity of primary afferents can be rapidly regulated not only by phosphorylation of receptors, ion channels and associated regulatory proteins but also by stimulus-induced cell surface expression of G-protein-coupled receptors. In chronic pain states the molecular characteristics of spinal nociceptive circuits are altered, enabling normal peripheral stimuli to induce pain hypersensitivity.
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Affiliation(s)
- Xu Zhang
- Institute of Neuroscience, Key Laboratory of Neurobiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
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25
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Jeong GB, Werner M, Gazula VR, Itoh T, Roberts M, David S, Pfister B, Cohen A, Neve RL, Hollmann M, Kalb R. Bi-directional control of motor neuron dendrite remodeling by the calcium permeability of AMPA receptors. Mol Cell Neurosci 2006; 32:299-314. [PMID: 16790357 DOI: 10.1016/j.mcn.2006.04.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 03/20/2006] [Accepted: 04/14/2006] [Indexed: 11/30/2022] Open
Abstract
Motor neurons express particularly high levels of the AMPA receptor subunit GluR1(Q)flip (GluR1(Q)i) during the period in early postnatal life when their dendritic tree grows and becomes more branched. To investigate how GluR1-containing AMPA receptors contribute to dendrite morphogenesis, we characterized a mutant form of GluR1 (containing a histidine in the Q/R editing site) with unique electrophysiological properties. Most notably, AMPA receptors assembled from GluR1(H)i display less calcium permeability than AMPA receptors assembled from GluR1(Q)i. Expression of GluR1(Q)i in vivo or in vitro led to an increase in dendrite branching with no net change in the overall tree size while GluR1(H)i led to a loss of branches and a net reduction in overall tree size. GluR1(H)i-dependent dendrite atrophy is mediated by protein phosphatase 2B. The results suggest that the electrophysiological properties of cell surface AMPA receptors, specifically their permeability to calcium, can be a central determinant of whether the dendrites undergo activity-dependent branching or atrophy.
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Affiliation(s)
- Goo-Bo Jeong
- Department of Anatomy, College of Medicine, Chungbuk National University, Cheong-ju 361-763, Republic of Korea
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26
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Dityatev A, Frischknecht R, Seidenbecher CI. Extracellular matrix and synaptic functions. Results Probl Cell Differ 2006; 43:69-97. [PMID: 17068968 DOI: 10.1007/400_025] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Comprehensive analysis of neuromuscular junction formation and recent data on synaptogenesis and long-term potentiation in the central nervous system revealed a number of extracellular matrix (ECM) molecules regulating different aspects of synaptic differentiation and function. The emerging mechanisms comprise interactions of ECM components with their cell surface receptors coupled to tyrosine kinase activities (agrin, integrin ligands, and reelin) and interactions with ion channels and transmitter receptors (Narp, tenascin-R and tenascin-C). These interactions may shape synaptic transmission and plasticity of excitatory synapses either via regulation of Ca2+ entry and postsynaptic expression of transmitter receptors or via control of GABAergic inhibition. The ECM molecules, derived from both neurons and glial cells and secreted into the extracellular space in an activity-dependent manner, may also shape synaptic plasticity through setting diffusion constraints for neurotransmitters, trophic factors and ions.
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Affiliation(s)
- Alexander Dityatev
- Institut für Neurophysiologie und Pathophysiologie, Universitätsklinikum Hamburg-Eppendorf, Germany.
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27
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Dityatev A, Schachner M. The extracellular matrix and synapses. Cell Tissue Res 2006; 326:647-54. [PMID: 16767406 DOI: 10.1007/s00441-006-0217-1] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Accepted: 04/20/2006] [Indexed: 11/27/2022]
Abstract
Extracellular matrix (ECM) molecules, derived from both neurons and glial cells, are secreted and accumulate in the extracellular space to regulate various aspects of pre- and postsynaptic differentiation, the maturation of synapses, and their plasticity. The emerging mechanisms comprise interactions of agrin, integrin ligands, and reelin, with their cognate cell-surface receptors being coupled to tyrosine kinase activities. These may induce the clustering of postsynaptic receptors and changes in their composition and function. Furthermore, direct interactions of laminins, neuronal pentraxins, and tenascin-R with voltage-gated Ca(2+) channels, alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA), and gamma-aminobutyric acid(B) (GABA(B)) receptors, respectively, shape the organization and function of different subsets of synapses. Some of these mechanisms significantly contribute to the induction of long-term potentiation in excitatory synapses, either by the regulation of Ca(2+) entry via N-methyl-D-aspartate receptors or L-type Ca(2+) channels, or by the control of GABAergic inhibition.
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Affiliation(s)
- Alexander Dityatev
- Institut für Neurophysiologie und Pathophysiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
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28
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Craig AM, Graf ER, Linhoff MW. How to build a central synapse: clues from cell culture. Trends Neurosci 2005; 29:8-20. [PMID: 16337695 PMCID: PMC2820512 DOI: 10.1016/j.tins.2005.11.002] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Revised: 08/31/2005] [Accepted: 11/10/2005] [Indexed: 01/10/2023]
Abstract
Central neurons develop and maintain molecularly distinct synaptic specializations for excitatory and inhibitory transmitters, often only microns apart on their dendritic arbor. Progress towards understanding the molecular basis of synaptogenesis has come from several recent studies using a coculture system of non-neuronal cells expressing molecules that generate presynaptic or postsynaptic "hemi-synapses" on contacting neurons. Together with molecular properties of these protein families, such studies have yielded interesting clues to how glutamatergic and GABAergic synapses are assembled. Other clues come from heterochronic cultures, manipulations of activity in subsets of neurons in a network, and of course many in vivo studies. Taking into account these data, we consider here how basic parameters of synapses--competence, placement, composition, size and longevity--might be determined.
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Affiliation(s)
- Ann Marie Craig
- Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver, Canada V6T 2B5.
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29
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Harms KJ, Craig AM. Synapse composition and organization following chronic activity blockade in cultured hippocampal neurons. J Comp Neurol 2005; 490:72-84. [PMID: 16041714 DOI: 10.1002/cne.20635] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Activity plays multiple roles in the expression of synaptic plasticity, and has been shown to regulate the localization of both neurotransmitter receptors and downstream signaling machinery. However, the role of activity in central synapse formation and organization is incompletely understood. Some studies indicate that synapse formation can occur in the absence of synaptic activity, while others indicate that activity is required for synapse maintenance and receptor recruitment. In addition, the effects of long-term blockade of transmission generally, rather than blockade of specific receptors, on postsynaptic protein complement has been poorly characterized. In order to address the role of activity in synapse formation and postsynaptic specialization, we used tetanus toxin to chronically cleave VAMP2 and inhibit SNARE-mediated neurotransmitter release in cultured hippocampal neurons. Although these neurons are deficient in synaptic release, they are of normal size and morphology. In addition, both excitatory and inhibitory synapses form along their processes with normal density. These synapses have a remarkably similar cellular and molecular organization compared to controls, and are capable of recruiting postsynaptic scaffolding proteins, GABA, and glutamate receptors. Subcellular enrichment of synaptic proteins into specialized domains also appears intact. These data indicate that global activity inhibition is insufficient to disrupt central synapse formation or organization.
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Affiliation(s)
- Kimberly J Harms
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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30
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Palmer CL, Cotton L, Henley JM. The molecular pharmacology and cell biology of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors. Pharmacol Rev 2005; 57:253-77. [PMID: 15914469 PMCID: PMC3314513 DOI: 10.1124/pr.57.2.7] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors (AMPARs) are of fundamental importance in the brain. They are responsible for the majority of fast excitatory synaptic transmission, and their overactivation is potently excitotoxic. Recent findings have implicated AMPARs in synapse formation and stabilization, and regulation of functional AMPARs is the principal mechanism underlying synaptic plasticity. Changes in AMPAR activity have been described in the pathology of numerous diseases, such as Alzheimer's disease, stroke, and epilepsy. Unsurprisingly, the developmental and activity-dependent changes in the functional synaptic expression of these receptors are under tight cellular regulation. The molecular and cellular mechanisms that control the postsynaptic insertion, arrangement, and lifetime of surface-expressed AMPARs are the subject of intense and widespread investigation. For example, there has been an explosion of information about proteins that interact with AMPAR subunits, and these interactors are beginning to provide real insight into the molecular and cellular mechanisms underlying the cell biology of AMPARs. As a result, there has been considerable progress in this field, and the aim of this review is to provide an account of the current state of knowledge.
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Affiliation(s)
- Claire L Palmer
- Medical Research Council Centre for Synaptic Plasticity, Department of Anatomy, School of Medical Sciences, Bristol University, Bristol, UK
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31
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Price MG, Davis CF, Deng F, Burgess DL. The alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate receptor trafficking regulator "stargazin" is related to the claudin family of proteins by Its ability to mediate cell-cell adhesion. J Biol Chem 2005; 280:19711-20. [PMID: 15760900 PMCID: PMC1255971 DOI: 10.1074/jbc.m500623200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Mutations in the Cacng2 gene encoding the neuronal transmembrane protein stargazin result in recessively inherited epilepsy and ataxia in "stargazer" mice. Functional studies suggest a dual role for stargazin, both as a modulatory gamma subunit for voltage-dependent calcium channels and as a regulator of post-synaptic membrane targeting for alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate (AMPA)-type glutamate receptors. Co-immunoprecipitation experiments demonstrate that stargazin can bind proteins of either complex in vivo, but it remains unclear whether it can associate with both complexes simultaneously. Cacng2 is one of eight closely related genes (Cacng1-8) encoding proteins with four transmembrane segments, cytoplasmic termini, and molecular masses between 25 and 44 kDa. This group of Cacng genes constitutes only one branch of a larger monophyletic assembly dominated by over 20 genes encoding proteins known as claudins. Claudins regulate cell adhesion and paracellular permeability as fundamental components of non-neuronal tight junctions. Because stargazin is structurally similar to claudins, we hypothesized that it might also have retained claudin-like functions inherited from a common ancestor. Here, we report that expression of stargazin in mouse L-fibroblasts results in cell aggregation comparable with that produced by claudins, and present evidence that the interaction is heterotypic and calcium dependent. The data suggest that the cell adhesion function of stargazin preceded its current role in neurons as a regulator of either voltage-dependent calcium channels or AMPA receptors. We speculate these complexes may have co-opted the established presence of stargazin at sites of close cell-cell contact to facilitate their own evolving intercellular signaling functions.
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Affiliation(s)
| | | | | | - Daniel L. Burgess
- From the Department of Neurology, Baylor College of Medicine, Houston, Texas 77030
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32
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Lachamp P, Balland B, Tell F, Baude A, Strube C, Crest M, Kessler JP. Early expression of AMPA receptors and lack of NMDA receptors in developing rat climbing fibre synapses. J Physiol 2005; 564:751-63. [PMID: 15731186 PMCID: PMC1464465 DOI: 10.1113/jphysiol.2005.084517] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Whether nascent glutamatergic synapses acquire their AMPA receptors constitutively or via a regulated pathway triggered by pre-existing NMDA receptor activation is still an open issue. Here, we provide evidence that some glutamatergic synapses develop without expressing NMDA receptors. Using immunocytochemistry, we showed that synapses between developing rat climbing fibres and Purkinje cells expressed GluR2-containing AMPA receptors as soon as they were formed (i.e. on embryonic day 19) but never carried detectable NMDA receptors. This was confirmed by electrophysiological recordings. Excitatory synaptic currents were recorded in Purkinje cells as early as P0. However, no NMDA receptor-mediated component was found in either spontaneous or evoked synaptic responses. In addition, we ruled out a possible role of extrasynaptic NMDA receptors by showing that AMPA receptor clustering at nascent climbing fibre synapses was not modified by chronic in utero NMDA receptor blockade.
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Affiliation(s)
- Philippe Lachamp
- Laboratoire de Neurophysiologie cellulaire, UMR CNRS 6150, Centre National de la Recherche Scientifique et Université de la Mediterrannée, IFR Jean Roche, Faculté de Médecine Nord, Bd Pierre Dramard, F13916 Marseille cedex 20, France
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