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Chen Y, Liu S, Jacobi AA, Jeng G, Ulrich JD, Stein IS, Patriarchi T, Hell JW. Rapid sequential clustering of NMDARs, CaMKII, and AMPARs upon activation of NMDARs at developing synapses. Front Synaptic Neurosci 2024; 16:1291262. [PMID: 38660466 PMCID: PMC11039796 DOI: 10.3389/fnsyn.2024.1291262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 03/22/2024] [Indexed: 04/26/2024] Open
Abstract
Rapid, synapse-specific neurotransmission requires the precise alignment of presynaptic neurotransmitter release and postsynaptic receptors. How postsynaptic glutamate receptor accumulation is induced during maturation is not well understood. We find that in cultures of dissociated hippocampal neurons at 11 days in vitro (DIV) numerous synaptic contacts already exhibit pronounced accumulations of the pre- and postsynaptic markers synaptotagmin, synaptophysin, synapsin, bassoon, VGluT1, PSD-95, and Shank. The presence of an initial set of AMPARs and NMDARs is indicated by miniature excitatory postsynaptic currents (mEPSCs). However, AMPAR and NMDAR immunostainings reveal rather smooth distributions throughout dendrites and synaptic enrichment is not obvious. We found that brief periods of Ca2+ influx through NMDARs induced a surprisingly rapid accumulation of NMDARs within 1 min, followed by accumulation of CaMKII and then AMPARs within 2-5 min. Postsynaptic clustering of NMDARs and AMPARs was paralleled by an increase in their mEPSC amplitudes. A peptide that blocked the interaction of NMDAR subunits with PSD-95 prevented the NMDAR clustering. NMDAR clustering persisted for 3 days indicating that brief periods of elevated glutamate fosters permanent accumulation of NMDARs at postsynaptic sites in maturing synapses. These data support the model that strong glutamatergic stimulation of immature glutamatergic synapses results in a fast and substantial increase in postsynaptic NMDAR content that required NMDAR binding to PSD-95 or its homologues and is followed by recruitment of CaMKII and subsequently AMPARs.
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Affiliation(s)
- Yucui Chen
- Department of Pharmacology, University of Iowa, Iowa City, IA, United States
| | - Shangming Liu
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Ariel A. Jacobi
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Grace Jeng
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Jason D. Ulrich
- Department of Pharmacology, University of Iowa, Iowa City, IA, United States
| | - Ivar S. Stein
- Department of Pharmacology, University of Iowa, Iowa City, IA, United States
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Tommaso Patriarchi
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Johannes W. Hell
- Department of Pharmacology, University of Iowa, Iowa City, IA, United States
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
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2
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Iacobucci GJ, Popescu GK. Calcium- and calmodulin-dependent inhibition of NMDA receptor currents. Biophys J 2024; 123:277-293. [PMID: 38140727 PMCID: PMC10870176 DOI: 10.1016/j.bpj.2023.12.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 12/05/2023] [Accepted: 12/19/2023] [Indexed: 12/24/2023] Open
Abstract
Calcium ions (Ca2+) reduce NMDA receptor currents through several distinct mechanisms. Among these, calmodulin (CaM)-dependent inhibition (CDI) accomplishes rapid, reversible, and incomplete reduction of the NMDA receptor currents in response to elevations in intracellular Ca2+. Quantitative and mechanistic descriptions of CDI of NMDA receptor-mediated signals have been marred by variability originating, in part, from differences in the conditions and metrics used to evaluate this process across laboratories. Recent ratiometric approaches to measure the magnitude and kinetics of NMDA receptor CDI have facilitated rapid insights into this phenomenon. Notably, the kinetics and magnitude of NMDA receptor CDI depend on the degree of saturation of its CaM binding sites, which represent the bona fide calcium sensor for this type of inhibition, the kinetics and magnitude of the Ca2+ signal, which depends on the biophysical properties of the NMDA receptor or of adjacent Ca2+ sources, and on the relative distribution of Ca2+ sources and CaM molecules. Given that all these factors vary widely during development, across cell types, and with physiological and pathological states, it is important to understand how NMDA receptor CDI develops and how it contributes to signaling in the central nervous system. Here, we review briefly these recent advances and highlight remaining questions about the structural and kinetic mechanisms of NMDA receptor CDI. Given that pathologies can arise from several sources, including mutations in the NMDA receptor and in CaM, understanding how CaM responds to intracellular Ca2+ signals to initiate conformational changes in NMDA receptors, and mapping the structural domains responsible will help to envision novel therapeutic strategies to neuropsychiatric diseases, which presently have limited available treatments.
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Affiliation(s)
- Gary J Iacobucci
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, SUNY, Buffalo, New York
| | - Gabriela K Popescu
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, SUNY, Buffalo, New York.
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3
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Rodríguez-Muñoz M, Cortés-Montero E, Onetti Y, Sánchez-Blázquez P, Garzón-Niño J. The σ1 Receptor and the HINT1 Protein Control α2δ1 Binding to Glutamate NMDA Receptors: Implications in Neuropathic Pain. Biomolecules 2021; 11:1681. [PMID: 34827679 PMCID: PMC8615847 DOI: 10.3390/biom11111681] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/29/2021] [Accepted: 11/08/2021] [Indexed: 02/01/2023] Open
Abstract
Nerve injury produces neuropathic pain through the binding of α2δ1 proteins to glutamate N-methyl-D-aspartate receptors (NMDARs). Notably, mice with a targeted deletion of the sigma 1 receptor (σ1R) gene do not develop neuropathy, whereas mice lacking the histidine triad nucleotide-binding protein 1 (Hint1) gene exhibit exacerbated allodynia. σ1R antagonists more effectively diminish neuropathic pain of spinal origin when administered by intracerebroventricular injection than systemically. Thus, in mice subjected to unilateral sciatic nerve chronic constriction injury (CCI), we studied the participation of σ1Rs and HINT1 proteins in the formation of α2δ1-NMDAR complexes within the supraspinal periaqueductal gray (PAG). We found that δ1 peptides required σ1Rs in order to interact with the NMDAR NR1 variant that contains the cytosolic C1 segment. σ1R antagonists or low calcium levels provoke the dissociation of σ1R-NR1 C1 dimers, while they barely affect the integrity of δ1-σ1R-NR1 C1 trimers. However, HINT1 does remove δ1 peptides from the trimer, thereby facilitating the subsequent dissociation of σ1Rs from NMDARs. In σ1R-/- mice, CCI does not promote the formation of NMDAR-α2δ1 complexes and allodynia does not develop. The levels of α2δ1-σ1R-NMDAR complexes increase in HINT1-/- mice and after inducing CCI, degradation of α2δ1 proteins is observed. Notably, σ1R antagonists but not gabapentinoids alleviate neuropathic pain in these mice. During severe neuropathy, the metabolism of α2δ1 proteins may account for the failure of many patients to respond to gabapentinoids. Therefore, σ1Rs promote and HINT1 proteins hinder the formation α2δ1-NMDAR complexes in the PAG, and hence, the appearance of mechanical allodynia depends on the interplay between these proteins.
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Affiliation(s)
- María Rodríguez-Muñoz
- Neuropharmacology, Department of Translational Neuroscience, Cajal Institute, CSIC, 28002 Madrid, Spain; (M.R.-M.); (E.C.-M.); (Y.O.); (P.S.-B.)
| | - Elsa Cortés-Montero
- Neuropharmacology, Department of Translational Neuroscience, Cajal Institute, CSIC, 28002 Madrid, Spain; (M.R.-M.); (E.C.-M.); (Y.O.); (P.S.-B.)
| | - Yara Onetti
- Neuropharmacology, Department of Translational Neuroscience, Cajal Institute, CSIC, 28002 Madrid, Spain; (M.R.-M.); (E.C.-M.); (Y.O.); (P.S.-B.)
| | - Pilar Sánchez-Blázquez
- Neuropharmacology, Department of Translational Neuroscience, Cajal Institute, CSIC, 28002 Madrid, Spain; (M.R.-M.); (E.C.-M.); (Y.O.); (P.S.-B.)
| | - Javier Garzón-Niño
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Doctor Arce 37, 28002 Madrid, Spain
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4
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Paul MH, Choi M, Schlaudraff J, Deller T, Del Turco D. Granule Cell Ensembles in Mouse Dentate Gyrus Rapidly Upregulate the Plasticity-Related Protein Synaptopodin after Exploration Behavior. Cereb Cortex 2021; 30:2185-2198. [PMID: 31812981 PMCID: PMC7175005 DOI: 10.1093/cercor/bhz231] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The plasticity-related protein Synaptopodin (SP) has been implicated in neuronal plasticity. SP is targeted to dendritic spines and the axon initial segment, where it organizes the endoplasmic reticulum (ER) into the spine apparatus and the cisternal organelle, respectively. Here, we report an inducible third localization of SP in the somata of activated granule cell ensembles in mouse dentate gyrus. Using immunofluorescence and fluorescence in situ hybridization, we observed a subpopulation of mature granule cells (~1–2%) exhibiting perinuclear SP protein and a strong somatic SP mRNA signal. Double immunofluorescence labeling for Arc demonstrated that ~ 75% of these somatic SP-positive cells are also Arc-positive. Placement of mice into a novel environment caused a rapid (~2–4 h) induction of Arc, SP mRNA, and SP protein in exploration-induced granule cell ensembles. Lesion experiments showed that this induction requires input from the entorhinal cortex. Somatic SP colocalized with α-Actinin2, a known binding partner of SP. Finally, ultrastructural analysis revealed SP immunoprecipitate on dense plates linking cytoplasmic and perinuclear ER cisterns; these structures were absent in granule cells of SP-deficient mice. Our data implicate SP in the formation of contextual representations in the dentate gyrus and the behaviorally induced reorganization of cytoplasmic and perinuclear ER.
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Affiliation(s)
- Mandy H Paul
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, D-60590 Frankfurt/Main, Germany
| | - Myoung Choi
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, D-60590 Frankfurt/Main, Germany
| | - Jessica Schlaudraff
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, D-60590 Frankfurt/Main, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, D-60590 Frankfurt/Main, Germany
| | - Domenico Del Turco
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, D-60590 Frankfurt/Main, Germany
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5
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Regulation of the NMDA receptor by its cytoplasmic domains: (How) is the tail wagging the dog? Neuropharmacology 2021; 195:108634. [PMID: 34097949 DOI: 10.1016/j.neuropharm.2021.108634] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 05/20/2021] [Accepted: 05/31/2021] [Indexed: 12/18/2022]
Abstract
Excitatory neurotransmission mediated by N-methyl-d-aspartate receptors (NMDARs) is critical for synapse development, function, and plasticity in the brain. NMDARs are tetra-heteromeric cation-channels that mediate synaptic transmission and plasticity. Extensive human studies show the existence of genetic variants in NMDAR subunits genes (GRIN genes) that are associated with neurodevelopmental and neuropsychiatric disorders, including autism spectrum disorders (ASD), epilepsy (EP), intellectual disability (ID), attention deficit hyperactivity disorder (ADHD), and schizophrenia (SCZ). NMDAR subunits have a unique modular architecture with four semiautonomous domains. Here we focus on the carboxyl terminal domain (CTD), also known as the intracellular C-tail, which varies in length among the glutamate receptor subunits and is the most diverse domain in terms of amino acid sequence. The CTD shows no sequence homology to any known proteins but encodes short docking motifs for intracellular binding proteins and covalent modifications. Our review will discuss the many important functions of the CTD in regulating NMDA membrane and synaptic targeting, stabilization, degradation targeting, allosteric modulation and metabotropic signaling of the receptor. This article is part of the special issue on 'Glutamate Receptors - NMDA Receptors'.
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6
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Pogoda A, Chmielewska N, Maciejak P, Szyndler J. Transcriptional Dysregulation in Huntington's Disease: The Role in Pathogenesis and Potency for Pharmacological Targeting. Curr Med Chem 2021; 28:2783-2806. [PMID: 32628586 DOI: 10.2174/0929867327666200705225821] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 05/15/2020] [Accepted: 06/19/2020] [Indexed: 11/22/2022]
Abstract
Huntington's disease (HD) is an inherited neurodegenerative disorder caused by a mutation in the gene that encodes a critical cell regulatory protein, huntingtin (Htt). The expansion of cytosine-adenine-guanine (CAG) trinucleotide repeats causes improper folding of functional proteins and is an initial trigger of pathological changes in the brain. Recent research has indicated that the functional dysregulation of many transcription factors underlies the neurodegenerative processes that accompany HD. These disturbances are caused not only by the loss of wild-type Htt (WT Htt) function but also by the occurrence of abnormalities that result from the action of mutant Htt (mHtt). In this review, we aim to describe the role of transcription factors that are currently thought to be strongly associated with HD pathogenesis, namely, RE1-silencing transcription factor, also known as neuron-restrictive silencer factor (REST/NRSF), forkhead box proteins (FOXPs), peroxisome proliferator-activated receptor gamma coactivator-1a (PGC1α), heat shock transcription factor 1 (HSF1), and nuclear factor κ light-chain-enhancer of activated B cells (NF- κB). We also take into account the role of these factors in the phenotype of HD as well as potential pharmacological interventions targeting the analyzed proteins. Furthermore, we considered whether molecular manipulation resulting in changes in transcription factor function may have clinical potency for treating HD.
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Affiliation(s)
- Aleksandra Pogoda
- Faculty of Medicine, Medical University of Warsaw, Zwirki i Wigury Street 61, 02-097 Warsaw, Poland
| | - Natalia Chmielewska
- Department of Neurochemistry, Institute of Psychiatry and Neurology, Sobieskiego Street 9, 02-957 Warsaw, Poland
| | - Piotr Maciejak
- Department of Neurochemistry, Institute of Psychiatry and Neurology, Sobieskiego Street 9, 02-957 Warsaw, Poland
| | - Janusz Szyndler
- Department of Experimental and Clinical Pharmacology, Centre for Preclinical Research and Technology CePT, Medical University of Warsaw, Banacha Street 1B, 02-097 Warsaw, Poland
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7
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Sbai O, Soussi R, Bole A, Khrestchatisky M, Esclapez M, Ferhat L. The actin binding protein α-actinin-2 expression is associated with dendritic spine plasticity and migrating granule cells in the rat dentate gyrus following pilocarpine-induced seizures. Exp Neurol 2020; 335:113512. [PMID: 33098872 DOI: 10.1016/j.expneurol.2020.113512] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/08/2020] [Accepted: 10/19/2020] [Indexed: 12/24/2022]
Abstract
α-actinin-2 (α-actn-2) is an F-actin-crosslinking protein, localized in dendritic spines. In vitro studies suggested that it is involved in spinogenesis, morphogenesis, actin organization, cell migration and anchoring of the NR1 subunit of the N-methyl-D-aspartate (NMDA) receptors in dendritic spines. However, little is known regarding its function in vivo. We examined the levels of α-actn-2 expression within the dentate gyrus (DG) during the development of chronic limbic seizures (epileptogenesis) induced by pilocarpine in rats. In this model, plasticity of the DG glutamatergic granule cells including spine loss, spinogenesis, morphogenesis, neo-synaptogenesis, aberrant migration, and alterations of NMDA receptors have been well characterized. We showed that α-actn-2 immunolabeling was reduced in the inner molecular layer at 1-2 weeks post-status epilepticus (SE), when granule cell spinogenesis and morphogenesis occur. This low level persisted at the chronic stage when new functional synapses are established. This decreased of α-actn-2 protein is concomitant with the recovery of drebrin A (DA), another actin-binding protein, at the chronic stage. Indeed, we demonstrated in cultured cells that in contrast to DA, α-actn-2 did not protect F-actin destabilization and DA inhibited α-actn-2 binding to F-actin. Such alteration could affect the anchoring of NR1 in dendritic spines. Furthermore, we showed that the expression of α-actn-2 and NR1 are co-down-regulated in membrane fractions of pilocarpine animals at chronic stage. Last, we showed that α-actn-2 is expressed in migrating newly born granule cells observed within the hilus of pilocarpine-treated rats. Altogether, our results suggest that α-actn-2 is not critical for the structural integrity and stabilization of granule cell dendritic spines. Instead, its expression is regulated when spinogenesis and morphogenesis occur and within migrating granule cells. Our data also suggest that the balance between α-actn-2 and DA expression levels may modulate NR1 anchoring within dendritic spines.
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Affiliation(s)
- Oualid Sbai
- Aix-Marseille Univ, CNRS, INP, Inst Neurophysiopathol, Marseille, France
| | - Rabia Soussi
- Aix-Marseille Univ, CNRS, INP, Inst Neurophysiopathol, Marseille, France
| | - Angélique Bole
- Aix-Marseille Univ, CNRS, INP, Inst Neurophysiopathol, Marseille, France
| | | | - Monique Esclapez
- Aix-Marseille Univ, INSERM, INS, Inst Neurosci Syst, Marseille, France
| | - Lotfi Ferhat
- Aix-Marseille Univ, CNRS, INP, Inst Neurophysiopathol, Marseille, France.
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8
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González-Tapia D, González-Tapia DC, Vázquez-Hernández N, Martínez-Torres NI, Flores-Soto M, González-Burgos I. Modifications to cytoskeleton-associated proteins in dendritic spines underlie the adaptive plasticity involved in long term reference memory. Neurobiol Learn Mem 2020; 172:107247. [DOI: 10.1016/j.nlm.2020.107247] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 04/27/2020] [Accepted: 05/06/2020] [Indexed: 01/01/2023]
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9
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Warnet XL, Bakke Krog H, Sevillano-Quispe OG, Poulsen H, Kjaergaard M. The C-terminal domains of the NMDA receptor: How intrinsically disordered tails affect signalling, plasticity and disease. Eur J Neurosci 2020; 54:6713-6739. [PMID: 32464691 DOI: 10.1111/ejn.14842] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 04/16/2020] [Accepted: 05/18/2020] [Indexed: 01/14/2023]
Abstract
NMDA receptors are part of the ionotropic glutamate receptor family, and are crucial for neurotransmission and memory. At the cellular level, the effects of activating these receptors include long-term potentiation (LTP) or depression (LTD). The NMDA receptor is a stringently gated cation channel permeable to Ca2+ , and it shares the molecular architecture of a tetrameric ligand-gated ion channel with the other family members. Its subunits, however, have uniquely long cytoplasmic C-terminal domains (CTDs). While the molecular gymnastics of the extracellular domains have been described in exquisite detail, much less is known about the structure and function of these CTDs. The CTDs vary dramatically in length and sequence between receptor subunits, but they all have a composition characteristic of intrinsically disordered proteins. The CTDs affect channel properties, trafficking and downstream signalling output from the receptor, and these functions are regulated by alternative splicing, protein-protein interactions, and post-translational modifications such as phosphorylation and palmitoylation. Here, we review the roles of the CTDs in synaptic plasticity with a focus on biochemical mechanisms. In total, the CTDs play a multifaceted role as a modifier of channel function, a regulator of cellular location and abundance, and signalling scaffold control the downstream signalling output.
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Affiliation(s)
- Xavier L Warnet
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,The Danish Research Institute for Translational Neuroscience (DANDRITE), Aarhus University, Aarhus, Denmark.,The Center for Proteins in Memory (PROMEMO), Aarhus University, Aarhus, Denmark
| | - Helle Bakke Krog
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,The Danish Research Institute for Translational Neuroscience (DANDRITE), Aarhus University, Aarhus, Denmark.,The Center for Proteins in Memory (PROMEMO), Aarhus University, Aarhus, Denmark
| | - Oscar G Sevillano-Quispe
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,The Danish Research Institute for Translational Neuroscience (DANDRITE), Aarhus University, Aarhus, Denmark.,The Center for Proteins in Memory (PROMEMO), Aarhus University, Aarhus, Denmark
| | - Hanne Poulsen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,The Danish Research Institute for Translational Neuroscience (DANDRITE), Aarhus University, Aarhus, Denmark.,The Center for Proteins in Memory (PROMEMO), Aarhus University, Aarhus, Denmark
| | - Magnus Kjaergaard
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,The Danish Research Institute for Translational Neuroscience (DANDRITE), Aarhus University, Aarhus, Denmark.,The Center for Proteins in Memory (PROMEMO), Aarhus University, Aarhus, Denmark
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10
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Mattingly TJ, Abdelwadoud M, Mullins CD, Eddington ND. Pharmapreneur - Defining a Framework for Entrepreneurship in Pharmacy Education. AMERICAN JOURNAL OF PHARMACEUTICAL EDUCATION 2019; 83:7548. [PMID: 32001888 PMCID: PMC6983887 DOI: 10.5688/ajpe7548] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 05/07/2019] [Indexed: 06/10/2023]
Abstract
Objective. To determine the role of entrepreneurism within the broader missions of schools of pharmacy and develop an educational framework to produce pharmacist entrepreneurs. Methods. Following a systematic review and six semi-structured interviews, a three-round Delphi process was conducted with an expert panel comprised of successful entrepreneurs, pharmacy faculty members and administrators, students, and community members. Participants were asked about the role of entrepreneurship in a pharmacy school's mission, how they would define a pharmacist entrepreneur, and to identify the knowledge, skills, and attitudes (KSAs) expected to be successful as a pharmacist entrepreneur. A model for entrepreneur education was also developed in accordance with Bloom's taxonomy. Participant agreement and rankings were reported. Results. Based on the semi-structured interviews and the results from the Delphi process, the following framework for a pharmacist entrepreneur was proposed along with a list of KSAs: identifies, creates, and pursues new opportunities; successfully implements new ideas into practice; is willing to take risks; fills unmet needs; creates new value through innovation; is responsive to change; makes sacrifices; includes social and intrapreneurship; leverages existing knowledge, skills, and resources; goes beyond traditional roles for pharmacists; and improves patient care. Recommendations for entrepreneurship instruction, guided by Bloom's taxonomy of cognitive processes, were created. Conclusion. According to our expert panel, a pharmacist entrepreneur combines several characteristics identified with a more traditional entrepreneur construct with the characteristics of an individual devoted to achieving outcomes beyond one's personal gain. Additional research to inform implementation and assessment of entrepreneurship within pharmacy curricula would provide more specific guidance for instructional design and accreditation evaluations.
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Affiliation(s)
- T Joseph Mattingly
- University of Maryland School of Pharmacy, Baltimore, Maryland
- Editorial Board Member, American Journal of Pharmaceutical Education, Arlington, Virginia
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11
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Iacobucci GJ, Popescu GK. Spatial Coupling Tunes NMDA Receptor Responses via Ca 2+ Diffusion. J Neurosci 2019; 39:8831-8844. [PMID: 31519826 PMCID: PMC6832682 DOI: 10.1523/jneurosci.0901-19.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 08/11/2019] [Accepted: 09/03/2019] [Indexed: 12/11/2022] Open
Abstract
In the CNS, NMDA receptors generate large and highly regulated Ca2+ signals, which are critical for synaptic development and plasticity. They are highly clustered at postsynaptic sites and along dendritic arbors, but whether this spatial arrangement affects their output is unknown. Synaptic NMDA receptor currents are subject to Ca2+-dependent inactivation (CDI), a type of activity-dependent inhibition that requires intracellular Ca2+ and calmodulin (CaM). We asked whether Ca2+ influx through a single NMDA receptor influences the activity of nearby NMDA receptors, as a possible coupling mechanism. Using cell-attached unitary current recordings from GluN1-2a/GluN2A receptors expressed in human HEK293 cells and from NMDA receptors native to hippocampal neurons from male and female rats, we recorded unitary currents from multichannel patches and used a coupled Markov model to determine the extent of signal coupling (κ). In the absence of extracellular Ca2+, we observed no cooperativity (κ < 0.1), whereas in 1.8 mm external Ca2+, both recombinant and native channels showed substantial negative cooperativity (κ = 0.27). Intracellular Ca2+ chelation or overexpression of a Ca2+-insensitive CaM mutant, reduced coupling, which is consistent with CDI representing the coupling mechanism. In contrast, cooperativity increased substantially (κ = 0.68) when overexpressing the postsynaptic scaffolding protein PSD-95, which increased receptor clustering. Together, these new results demonstrate that NMDA receptor currents are negatively coupled through CDI, and the degree of coupling can be tuned by the distance between receptors. Therefore, channel clustering can influence the activity-dependent reduction in NMDA receptor currents.SIGNIFICANCE STATEMENT At central synapses, NMDA receptors are a major class of excitatory glutamate-gated channels and a source of activity-dependent Ca2+ influx. In turn, fluxed Ca2+ ions bind to calmodulin-primed receptors and reduce further entry, through an autoinhibitory mechanism known as Ca2+ -dependent inactivation (CDI). Here, we show that the diffusion of fluxed Ca2+ between active channels situated within submicroscopic distances amplified receptor inactivation. Thus, calmodulin-mediated gating modulation, an evolutionarily conserved regulatory mechanism, endows synapses with sensitivity to both the temporal sequence and spatial distribution of Ca2+ signals. Perturbations in this mechanism, which coordinates the activity of NMDA receptors within a cluster, may cause signaling alterations that contribute to neuropsychiatric conditions.
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Affiliation(s)
- Gary J Iacobucci
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, New York 14206
| | - Gabriela K Popescu
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, New York 14206
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12
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The CaMKII/NMDA receptor complex controls hippocampal synaptic transmission by kinase-dependent and independent mechanisms. Nat Commun 2018; 9:2069. [PMID: 29802289 PMCID: PMC5970233 DOI: 10.1038/s41467-018-04439-7] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 04/16/2018] [Indexed: 02/06/2023] Open
Abstract
CaMKII is one of the most studied synaptic proteins, but many critical issues regarding its role in synaptic function remain unresolved. Using a CRISPR-based system to delete CaMKII and replace it with mutated forms in single neurons, we have rigorously addressed its various synaptic roles. In brief, basal AMPAR and NMDAR synaptic transmission both require CaMKIIα, but not CaMKIIβ, indicating that, even in the adult, synaptic transmission is determined by the ongoing action of CaMKIIα. While AMPAR transmission requires kinase activity, NMDAR transmission does not, implying a scaffolding role for the CaMKII protein instead. LTP is abolished in the absence of CaMKIIα and/or CaMKIIβ and with an autophosphorylation impaired CaMKIIα (T286A). With the exception of NMDAR synaptic currents, all aspects of CaMKIIα signaling examined require binding to the NMDAR, emphasizing the essential role of this receptor as a master synaptic signaling hub. Calcium-calmodulin-dependent protein kinase II (CaMKII) is well known for its roles in synaptic plasticity. Using a series of molecular replacement experiments, the authors show that the kinase function of CaMKII is required for long-term plasticity and basal AMPA receptor-mediated transmission.
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13
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Matt L, Kim K, Hergarden AC, Patriarchi T, Malik ZA, Park DK, Chowdhury D, Buonarati OR, Henderson PB, Gökçek Saraç Ç, Zhang Y, Mohapatra D, Horne MC, Ames JB, Hell JW. α-Actinin Anchors PSD-95 at Postsynaptic Sites. Neuron 2018; 97:1094-1109.e9. [PMID: 29429936 PMCID: PMC5963734 DOI: 10.1016/j.neuron.2018.01.036] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 12/10/2017] [Accepted: 01/17/2018] [Indexed: 12/17/2022]
Abstract
Despite the central role PSD-95 plays in anchoring postsynaptic AMPARs, how PSD-95 itself is tethered to postsynaptic sites is not well understood. Here we show that the F-actin binding protein α-actinin binds to the very N terminus of PSD-95. Knockdown (KD) of α-actinin phenocopies KD of PSD-95. Mutating lysine at position 10 or lysine at position 11 of PSD-95 to glutamate, or glutamate at position 53 or glutamate and aspartate at positions 213 and 217 of α-actinin, respectively, to lysine impairs, in parallel, PSD-95 binding to α-actinin and postsynaptic localization of PSD-95 and AMPARs. These experiments identify α-actinin as a critical PSD-95 anchor tethering the AMPAR-PSD-95 complex to postsynaptic sites.
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Affiliation(s)
- Lucas Matt
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | - Karam Kim
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | - Anne C Hergarden
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | - Tommaso Patriarchi
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | - Zulfiqar A Malik
- Department of Pharmacology, University of California, Davis, Davis, CA, USA; Department of Pharmacology, University of Iowa, Iowa City, IA, USA
| | - Deborah K Park
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | | | - Olivia R Buonarati
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | - Peter B Henderson
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | - Çiğdem Gökçek Saraç
- Department of Pharmacology, University of California, Davis, Davis, CA, USA; Department of Biomedical Engineering, Faculty of Engineering, Akdeniz University, Antalya, Turkey
| | - Yonghong Zhang
- Department of Chemistry, University of California, Davis, Davis, CA, USA
| | - Durga Mohapatra
- Department of Pharmacology, University of Iowa, Iowa City, IA, USA
| | - Mary C Horne
- Department of Pharmacology, University of California, Davis, Davis, CA, USA; Department of Pharmacology, University of Iowa, Iowa City, IA, USA
| | - James B Ames
- Department of Chemistry, University of California, Davis, Davis, CA, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, Davis, CA, USA; Department of Pharmacology, University of Iowa, Iowa City, IA, USA.
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14
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Iacobucci GJ, Popescu GK. Resident Calmodulin Primes NMDA Receptors for Ca 2+-Dependent Inactivation. Biophys J 2017; 113:2236-2248. [PMID: 28712640 PMCID: PMC5700250 DOI: 10.1016/j.bpj.2017.06.035] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 06/09/2017] [Accepted: 06/13/2017] [Indexed: 10/19/2022] Open
Abstract
N-methyl-d-aspartate (NMDA) receptors are glutamate- and glycine-gated channels that flux Na+ and Ca2+ into postsynaptic neurons during synaptic transmission. The resulting intracellular Ca2+ transient is essential to physiological and pathological processes related to synaptic development, plasticity, and apoptosis. It also engages calmodulin (CaM) to reduce subsequent NMDA receptor activity in a process known as Ca2+-dependent inactivation (CDI). Here, we used whole-cell electrophysiology to measure CDI and computational modeling to dissect the sequence of events that underlies it. With these approaches, we estimate that CaM senses NMDA receptor Ca2+ influx at ∼9 nm from the channel pore. Further, when we controlled the frequency of Ca2+ influx through individual channels, we found that a kinetic model where apoCaM associates with channels before their activation best predicts the measured CDI. These results provide, to our knowledge, novel functional evidence for CaM preassociation to NMDA receptors in living cells. This particular mechanism for autoinhibitory feedback reveals strategies and challenges for Ca2+ regulation in neurons during physiological synaptic activity and disease.
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Affiliation(s)
- Gary J Iacobucci
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York.
| | - Gabriela K Popescu
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York.
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15
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Oswald RE. New Insights into the Mechanism of Ca 2+-Dependent Inactivation of NMDA Receptors. Biophys J 2017; 113:2131-2132. [PMID: 29102038 DOI: 10.1016/j.bpj.2017.10.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 10/02/2017] [Accepted: 10/03/2017] [Indexed: 10/18/2022] Open
Affiliation(s)
- Robert E Oswald
- Department of Molecular Medicine, Cornell University, Ithaca, New York.
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16
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Kim K, Saneyoshi T, Hosokawa T, Okamoto K, Hayashi Y. Interplay of enzymatic and structural functions of CaMKII in long-term potentiation. J Neurochem 2016; 139:959-972. [DOI: 10.1111/jnc.13672] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 05/09/2016] [Accepted: 05/10/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Karam Kim
- Brain Science Institute; RIKEN; Wako Saitama Japan
| | | | | | - Kenichi Okamoto
- Lunenfeld-Tanenbaum Research Institute; Mount Sinai Hospital; Toronto ON Canada
- Department of Molecular Genetics; Faculty of Medicine; University of Toronto; Toronto ON Canada
| | - Yasunori Hayashi
- Brain Science Institute; RIKEN; Wako Saitama Japan
- Saitama University Brain Science Institute; Saitama University; Saitama Japan
- School of Life Science; South China Normal University; Guangzhou China
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17
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Kalinowska M, Chávez AE, Lutzu S, Castillo PE, Bukauskas FF, Francesconi A. Actinin-4 Governs Dendritic Spine Dynamics and Promotes Their Remodeling by Metabotropic Glutamate Receptors. J Biol Chem 2015; 290:15909-20. [PMID: 25944910 DOI: 10.1074/jbc.m115.640136] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Indexed: 11/06/2022] Open
Abstract
Dendritic spines are dynamic, actin-rich protrusions in neurons that undergo remodeling during neuronal development and activity-dependent plasticity within the central nervous system. Although group 1 metabotropic glutamate receptors (mGluRs) are critical for spine remodeling under physiopathological conditions, the molecular components linking receptor activity to structural plasticity remain unknown. Here we identify a Ca(2+)-sensitive actin-binding protein, α-actinin-4, as a novel group 1 mGluR-interacting partner that orchestrates spine dynamics and morphogenesis in primary neurons. Functional silencing of α-actinin-4 abolished spine elongation and turnover stimulated by group 1 mGluRs despite intact surface receptor expression and downstream ERK1/2 signaling. This function of α-actinin-4 in spine dynamics was underscored by gain-of-function phenotypes in untreated neurons. Here α-actinin-4 induced spine head enlargement, a morphological change requiring the C-terminal domain of α-actinin-4 that binds to CaMKII, an interaction we showed to be regulated by group 1 mGluR activation. Our data provide mechanistic insights into spine remodeling by metabotropic signaling and identify α-actinin-4 as a critical effector of structural plasticity within neurons.
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Affiliation(s)
- Magdalena Kalinowska
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Andrés E Chávez
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Stefano Lutzu
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Pablo E Castillo
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Feliksas F Bukauskas
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Anna Francesconi
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
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18
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Rodríguez-Muñoz M, Sánchez-Blázquez P, Herrero-Labrador R, Martínez-Murillo R, Merlos M, Vela JM, Garzón J. The σ1 receptor engages the redox-regulated HINT1 protein to bring opioid analgesia under NMDA receptor negative control. Antioxid Redox Signal 2015; 22:799-818. [PMID: 25557043 PMCID: PMC4367239 DOI: 10.1089/ars.2014.5993] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 12/16/2014] [Accepted: 01/01/2015] [Indexed: 12/12/2022]
Abstract
AIMS The in vivo pharmacology of the sigma 1 receptor (σ1R) is certainly complex; however, σ1R antagonists are of therapeutic interest, because they enhance mu-opioid receptor (MOR)-mediated antinociception and reduce neuropathic pain. Thus, we investigated whether the σ1R is involved in the negative control that glutamate N-methyl-d-aspartate acid receptors (NMDARs) exert on opioid antinociception. RESULTS The MOR C terminus carries the histidine triad nucleotide-binding protein 1 (HINT1) coupled to the regulator of G-protein signaling RGSZ2-neural nitric oxide synthase assembly. Activated MORs stimulate the production of nitric oxide (NO), and the redox zinc switch RGSZ2 converts this signal into free zinc ions that are required to recruit the redox sensor PKCγ to HINT1 proteins. Then, PKCγ impairs HINT1-RGSZ2 association and enables σ1R-NR1 interaction with MOR-HINT1 complexes to restrain opioid signaling. The inhibition of NOS or the absence of σ1Rs prevents HINT1-PKCγ interaction, and MOR-NMDAR cross-regulation fails. The σ1R antagonists transitorily remove the binding of σ1Rs to NR1 subunits, facilitate the entrance of negative regulators of NMDARs, likely Ca(2+)-CaM, and prevent NR1 interaction with HINT1, thereby impairing the negative feedback of glutamate on opioid analgesia. INNOVATION A redox-regulated process situates MOR signaling under NMDAR control, and in this context, the σ1R binds to the cytosolic C terminal region of the NMDAR NR1 subunit. CONCLUSION The σ1R antagonists enhance opioid analgesia in naïve mice by releasing MORs from the negative influence of NMDARs, and they also reset antinociception in morphine tolerant animals. Moreover, σ1R antagonists alleviate neuropathic pain, probably by driving the inhibition of up-regulated NMDARs.
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Affiliation(s)
- María Rodríguez-Muñoz
- Neurofarmacología, Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Pilar Sánchez-Blázquez
- Neurofarmacología, Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Raquel Herrero-Labrador
- Neurofarmacología, Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Ricardo Martínez-Murillo
- Neurofarmacología, Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Manuel Merlos
- Drug Discovery & Preclinical Development, Esteve, Barcelona, Spain
| | - José Miguel Vela
- Drug Discovery & Preclinical Development, Esteve, Barcelona, Spain
| | - Javier Garzón
- Neurofarmacología, Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
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19
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Ning L, Paetau S, Nyman-Huttunen H, Tian L, Gahmberg CG. ICAM-5 affects spine maturation by regulation of NMDA receptor binding to α-actinin. Biol Open 2015; 4:125-36. [PMID: 25572420 PMCID: PMC4365481 DOI: 10.1242/bio.201410439] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
ICAM-5 is a negative regulator of dendritic spine maturation and facilitates the formation of filopodia. Its absence results in improved memory functions, but the mechanisms have remained poorly understood. Activation of NMDA receptors induces ICAM-5 ectodomain cleavage through a matrix metalloproteinase (MMP)-dependent pathway, which promotes spine maturation and synapse formation. Here, we report a novel, ICAM-5-dependent mechanism underlying spine maturation by regulating the dynamics and synaptic distribution of α-actinin. We found that GluN1 and ICAM-5 partially compete for the binding to α-actinin; deletion of the cytoplasmic tail of ICAM-5 or ablation of the gene resulted in increased association of GluN1 with α-actinin, whereas internalization of ICAM-5 peptide perturbed the GluN1/α-actinin interaction. NMDA treatment decreased α-actinin binding to ICAM-5, and increased the binding to GluN1. Proper synaptic distribution of α-actinin requires the ICAM-5 cytoplasmic domain, without which α-actinin tended to accumulate in filopodia, leading to F-actin reorganization. The results indicate that ICAM-5 retards spine maturation by preventing reorganization of the actin cytoskeleton, but NMDA receptor activation is sufficient to relieve the brake and promote the maturation of spines.
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Affiliation(s)
- Lin Ning
- Division of Biochemistry and Biotechnology, Faculty of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 5, FIN-00014, Helsinki, Finland
| | - Sonja Paetau
- Division of Biochemistry and Biotechnology, Faculty of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 5, FIN-00014, Helsinki, Finland
| | - Henrietta Nyman-Huttunen
- Division of Biochemistry and Biotechnology, Faculty of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 5, FIN-00014, Helsinki, Finland
| | - Li Tian
- Neuroscience Center, University of Helsinki, Viikinkaari 4, FIN-00014, Helsinki, Finland
| | - Carl G Gahmberg
- Division of Biochemistry and Biotechnology, Faculty of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 5, FIN-00014, Helsinki, Finland
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20
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Lisman J, Raghavachari S. Biochemical principles underlying the stable maintenance of LTP by the CaMKII/NMDAR complex. Brain Res 2014; 1621:51-61. [PMID: 25511992 DOI: 10.1016/j.brainres.2014.12.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 12/01/2014] [Accepted: 12/03/2014] [Indexed: 11/17/2022]
Abstract
Memory involves the storage of information at synapses by an LTP-like process. This information storage is synapse specific and can endure for years despite the turnover of all synaptic proteins. There must, therefore, be special principles that underlie the stability of LTP. Recent experimental results suggest that LTP is maintained by the complex of CaMKII with the NMDAR. Here we consider the specifics of the CaMKII/NMDAR molecular switch, with the goal of understanding the biochemical principles that underlie stable information storage by synapses. Consideration of a variety of experimental results suggests that multiple principles are involved. One switch requirement is to prevent spontaneous transitions from the off to the on state. The highly cooperative nature of CaMKII autophosphorylation by Ca(2+) (Hill coefficient of 8) and the fact that formation of the CaMKII/NMDAR complex requires release of CaMKII from actin are mechanisms that stabilize the off state. The stability of the on state depends critically on intersubunit autophosphorylation, a process that restores any loss of pT286 due to phosphatase activity. Intersubunit autophosphorylation is also important in explaining why on state stability is not compromised by protein turnover. Recent evidence suggests that turnover occurs by subunit exchange. Thus, stability could be achieved if a newly inserted unphosphorylated subunit was autophosphorylated by a neighboring subunit. Based on other recent work, we posit a novel mechanism that enhances the stability of the on state by protection of pT286 from phosphatases. We posit that the binding of the NMNDAR to CaMKII forces pT286 into the catalytic site of a neighboring subunit, thereby protecting pT286 from phosphatases. A final principle concerns the role of structural changes. The binding of CaMKII to the NMDAR may act as a tag to organize the binding of further proteins that produce the synapse enlargement that underlies late LTP. We argue that these structural changes not only enhance transmission, but also enhance the stability of the CaMKII/NMDAR complex. Together, these principles provide a mechanistic framework for understanding how individual synapses produce stable information storage. This article is part of a Special Issue entitled SI: Brain and Memory.
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Affiliation(s)
- John Lisman
- Brandeis University, Department of Biology and Volen Center for Complex Systems, 415 South Street-MS008, Waltham, MA 02454, United States Minor Outlying Islands.
| | - Sridhar Raghavachari
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, United States
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21
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Scholl ES, Pirone A, Cox DH, Duncan RK, Jacob MH. Alternative splice isoforms of small conductance calcium-activated SK2 channels differ in molecular interactions and surface levels. Channels (Austin) 2014; 8:62-75. [PMID: 24394769 PMCID: PMC4048344 DOI: 10.4161/chan.27470] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Small conductance Ca2+-sensitive potassium (SK2) channels are voltage-independent, Ca2+-activated ion channels that conduct potassium cations and thereby modulate the intrinsic excitability and synaptic transmission of neurons and sensory hair cells. In the cochlea, SK2 channels are functionally coupled to the highly Ca2+ permeant α9/10-nicotinic acetylcholine receptors (nAChRs) at olivocochlear postsynaptic sites. SK2 activation leads to outer hair cell hyperpolarization and frequency-selective suppression of afferent sound transmission. These inhibitory responses are essential for normal regulation of sound sensitivity, frequency selectivity, and suppression of background noise. However, little is known about the molecular interactions of these key functional channels. Here we show that SK2 channels co-precipitate with α9/10-nAChRs and with the actin-binding protein α-actinin-1. SK2 alternative splicing, resulting in a 3 amino acid insertion in the intracellular 3′ terminus, modulates these interactions. Further, relative abundance of the SK2 splice variants changes during developmental stages of synapse maturation in both the avian cochlea and the mammalian forebrain. Using heterologous cell expression to separately study the 2 distinct isoforms, we show that the variants differ in protein interactions and surface expression levels, and that Ca2+ and Ca2+-bound calmodulin differentially regulate their protein interactions. Our findings suggest that the SK2 isoforms may be distinctly modulated by activity-induced Ca2+ influx. Alternative splicing of SK2 may serve as a novel mechanism to differentially regulate the maturation and function of olivocochlear and neuronal synapses.
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Affiliation(s)
- Elizabeth Storer Scholl
- Department of Neuroscience; Tufts University Sackler School of Graduate Biomedical Sciences; Boston, MA USA
| | - Antonella Pirone
- Department of Neuroscience; Tufts University Sackler School of Graduate Biomedical Sciences; Boston, MA USA
| | - Daniel H Cox
- Department of Neuroscience; Tufts University Sackler School of Graduate Biomedical Sciences; Boston, MA USA
| | - R Keith Duncan
- Department of Otolaryngology; University of Michigan; Ann Arbor, MI USA
| | - Michele H Jacob
- Department of Neuroscience; Tufts University Sackler School of Graduate Biomedical Sciences; Boston, MA USA
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22
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Abstract
The ability to induce and study neuronal plasticity in single dendritic spines has greatly advanced our understanding of the signaling mechanisms that mediate long-term potentiation. It is now clear that in addition to compartmentalization by the individual spine, subcompartmentalization of biochemical signals occurs at specialized microdomains within the spine. The spatiotemporal coordination of these complex cascades allows for the concomitant remodeling of the postsynaptic density and actin spinoskeleton and for the regulation of membrane traffic to express functional and structural plasticity. Here, we highlight recent findings in the signaling cascades at spine microdomains as well as the challenges and approaches to studying plasticity at the spine level.
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Affiliation(s)
- Lesley A Colgan
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458; ,
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23
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Vicente-Sánchez A, Sánchez-Blázquez P, Rodríguez-Muñoz M, Garzón J. HINT1 protein cooperates with cannabinoid 1 receptor to negatively regulate glutamate NMDA receptor activity. Mol Brain 2013; 6:42. [PMID: 24093505 PMCID: PMC3851374 DOI: 10.1186/1756-6606-6-42] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 09/19/2013] [Indexed: 01/02/2023] Open
Abstract
Background G protein-coupled receptors (GPCRs) are the targets of a large number of drugs currently in therapeutic use. Likewise, the glutamate ionotropic N-methyl-D-aspartate receptor (NMDAR) has been implicated in certain neurological disorders, such as neurodegeration, neuropathic pain and mood disorders, as well as psychosis and schizophrenia. Thus, there is now an important need to characterize the interactions between GPCRs and NMDARs. Indeed, these interactions can produce distinct effects, and whereas the activation of Mu-opioid receptor (MOR) increases the calcium fluxes associated to NMDARs, that of type 1 cannabinoid receptor (CNR1) antagonizes their permeation. Notably, a series of proteins interact with these receptors affecting their responses and interactions, and then emerge as novel therapeutic targets for the aforementioned pathologies. Results We found that in the presence of GPCRs, the HINT1 protein influences the activity of NMDARs, whereby NMDAR activation was enhanced in CNR1+/+/HINT1-/- cortical neurons and the cannabinoid agonist WIN55,212-2 provided these cells with no protection against a NMDA insult. NMDAR activity was normalized in these cells by the lentiviral expression of HINT1, which also restored the neuroprotection mediated by cannabinoids. NMDAR activity was also enhanced in CNR1-/-/HINT1+/+ neurons, although this activity was dampened by the expression of GPCRs like the MOR, CNR1 or serotonin 1A (5HT1AR). Conclusions The HINT1 protein plays an essential role in the GPCR-NMDAR connection. In the absence of receptor activation, GPCRs collaborate with HINT1 proteins to negatively control NMDAR activity. When activated, most GPCRs release the control of HINT1 and NMDAR responsiveness is enhanced. However, cannabinoids that act through CNR1 maintain the negative control of HINT1 on NMDAR function and their protection against glutamate excitotoxic insult persists.
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24
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Hall DD, Dai S, Tseng PY, Malik Z, Nguyen M, Matt L, Schnizler K, Shephard A, Mohapatra DP, Tsuruta F, Dolmetsch RE, Christel CJ, Lee A, Burette A, Weinberg RJ, Hell JW. Competition between α-actinin and Ca²⁺-calmodulin controls surface retention of the L-type Ca²⁺ channel Ca(V)1.2. Neuron 2013; 78:483-97. [PMID: 23664615 DOI: 10.1016/j.neuron.2013.02.032] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2013] [Indexed: 12/30/2022]
Abstract
Regulation of neuronal excitability and cardiac excitation-contraction coupling requires the proper localization of L-type Ca²⁺ channels. We show that the actin-binding protein α-actinin binds to the C-terminal surface targeting motif of α11.2, the central pore-forming Ca(V)1.2 subunit, in order to foster its surface expression. Disruption of α-actinin function by dominant-negative or small hairpin RNA constructs reduces Ca(V)1.2 surface localization in human embryonic kidney 293 and neuronal cultures and dendritic spine localization in neurons. We demonstrate that calmodulin displaces α-actinin from their shared binding site on α11.2 upon Ca²⁺ influx through L-type channels, but not through NMDAR, thereby triggering loss of Ca(V)1.2 from spines. Coexpression of a Ca²⁺-binding-deficient calmodulin mutant does not affect basal Ca(V)1.2 surface expression but inhibits its internalization upon Ca²⁺ influx. We conclude that α-actinin stabilizes Ca(V)1.2 at the plasma membrane and that its displacement by Ca²⁺-calmodulin triggers Ca²⁺-induced endocytosis of Ca(V)1.2, thus providing an important negative feedback mechanism for Ca²⁺ influx.
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Affiliation(s)
- Duane D Hall
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242, USA
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25
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Rácz B, Weinberg RJ. Microdomains in forebrain spines: an ultrastructural perspective. Mol Neurobiol 2013; 47:77-89. [PMID: 22983912 PMCID: PMC3538892 DOI: 10.1007/s12035-012-8345-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Accepted: 08/27/2012] [Indexed: 12/21/2022]
Abstract
Glutamatergic axons in the mammalian forebrain terminate predominantly onto dendritic spines. Long-term changes in the efficacy of these excitatory synapses are tightly coupled to changes in spine morphology. The reorganization of the actin cytoskeleton underlying this spine "morphing" involves numerous proteins that provide the machinery needed for adaptive cytoskeletal remodeling. Here, we review recent literature addressing the chemical architecture of the spine, focusing mainly on actin-binding proteins (ABPs). Accumulating evidence suggests that ABPs are organized into functionally distinct microdomains within the spine cytoplasm. This functional compartmentalization provides a structural basis for regulation of the spinoskeleton, offering a novel window into mechanisms underlying synaptic plasticity.
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Affiliation(s)
- Bence Rácz
- Department of Anatomy and Histology, Faculty of Veterinary Science, Szent István University, 1078, Budapest, Hungary.
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26
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Jalan-Sakrikar N, Bartlett RK, Baucum AJ, Colbran RJ. Substrate-selective and calcium-independent activation of CaMKII by α-actinin. J Biol Chem 2012; 287:15275-83. [PMID: 22427672 PMCID: PMC3346149 DOI: 10.1074/jbc.m112.351817] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 03/14/2012] [Indexed: 11/06/2022] Open
Abstract
Protein-protein interactions are thought to modulate the efficiency and specificity of Ca(2+)/calmodulin (CaM)-dependent protein kinase II (CaMKII) signaling in specific subcellular compartments. Here we show that the F-actin-binding protein α-actinin targets CaMKIIα to F-actin in cells by binding to the CaMKII regulatory domain, mimicking CaM. The interaction with α-actinin is blocked by CaMKII autophosphorylation at Thr-306, but not by autophosphorylation at Thr-305, whereas autophosphorylation at either site blocks Ca(2+)/CaM binding. The binding of α-actinin to CaMKII is Ca(2+)-independent and activates the phosphorylation of a subset of substrates in vitro. In intact cells, α-actinin selectively stabilizes CaMKII association with GluN2B-containing glutamate receptors and enhances phosphorylation of Ser-1303 in GluN2B, but inhibits CaMKII phosphorylation of Ser-831 in glutamate receptor GluA1 subunits by competing for activation by Ca(2+)/CaM. These data show that Ca(2+)-independent binding of α-actinin to CaMKII differentially modulates the phosphorylation of physiological targets that play key roles in long-term synaptic plasticity.
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Affiliation(s)
| | | | | | - Roger J. Colbran
- From the Department of Molecular Physiology and Biophysics
- Vanderbilt Brain Institute, and
- Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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Swulius MT, Farley MM, Bryant MA, Waxham MN. Electron cryotomography of postsynaptic densities during development reveals a mechanism of assembly. Neuroscience 2012; 212:19-29. [PMID: 22516021 DOI: 10.1016/j.neuroscience.2012.03.042] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 03/27/2012] [Accepted: 03/28/2012] [Indexed: 01/10/2023]
Abstract
Postsynaptic densities (PSDs) are responsible for organizing receptors and signaling proteins that regulate excitatory transmission in the mammalian brain. To better understand the assembly and 3D organization of this synaptic structure, we employed electron cryotomography to visualize general and fine structural details of PSDs isolated from P2, P14, P21 and adult forebrain in the absence of fixatives and stains. PSDs at P2 are a loose mesh of filamentous and globular proteins and during development additional protein complexes are recruited onto the mesh. Quantitative analysis reveals that while the surface area of PSDs is relatively constant, the thickness and protein occupancy of the PSD volume increase dramatically between P14 and adult. One striking morphological feature is the appearance of lipid raft-like structures, first evident in PSDs from 14 day old animals. These detergent-resistant membranes stain for GM1 ganglioside and their terminations can be clearly seen embedded in protein "bowls" within the PSD complex. In total, these results lead to the conclusion that the PSD is assembled by the gradual recruitment and stabilization of proteins within an initial mesh that systematically adds complexity to the structure.
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Affiliation(s)
- M T Swulius
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, Houston, TX 77030, USA
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28
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Wang K, Wang Y. Negative modulation of NMDA receptor channel function by DREAM/calsenilin/KChIP3 provides neuroprotection? Front Mol Neurosci 2012; 5:39. [PMID: 22518099 PMCID: PMC3325484 DOI: 10.3389/fnmol.2012.00039] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Accepted: 03/15/2012] [Indexed: 01/08/2023] Open
Abstract
N-methyl-D-aspartate receptors (NMDARs) are glutamate-gated ion channels highly permeable to calcium and essential to excitatory neurotransmission. The NMDARs have attracted much attention because of their role in synaptic plasticity and excitotoxicity. Evidence has recently accumulated that NMDARs are negatively regulated by intracellular calcium binding proteins. The calcium-dependent suppression of NMDAR function serves as a feedback mechanism capable of regulating subsequent Ca2+ entry into the postsynaptic cell, and may offer an alternative approach to treating NMDAR-mediated excitotoxic injury. This short review summarizes the recent progress made in understanding the negative modulation of NMDAR function by DREAM/calsenilin/KChIP3, a neuronal calcium sensor (NCS) protein.
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Affiliation(s)
- Kewei Wang
- Department of Molecular and Cellular Pharmacology, State Key Laboratory of Natural and Biomimetic Drugs, Peking University School of Pharmaceutical Sciences Beijing, China
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29
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Brunelli L, Llansola M, Felipo V, Campagna R, Airoldi L, De Paola M, Fanelli R, Mariani A, Mazzoletti M, Pastorelli R. Insight into the neuroproteomics effects of the food-contaminant non-dioxin like polychlorinated biphenyls. J Proteomics 2012; 75:2417-30. [PMID: 22387315 DOI: 10.1016/j.jprot.2012.02.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 02/14/2012] [Accepted: 02/16/2012] [Indexed: 01/20/2023]
Abstract
Recent studies showed that food-contaminant non-dioxin-like polychlorinated biphenyls (NDL-PCBs) congeners (PCB52, PCB138, PCB180) have neurotoxic potential, but the cellular and molecular mechanisms underlying neuronal damage are not entirely known. The aim of this study was to assess whether in-vitro exposure to NDL-PCBs may alter the proteome profile of primary cerebellar neurons in order to expand our knowledge on NDL-PCBs neurotoxicity. Comparison of proteome from unexposed and exposed rat cerebellar neurons was performed using state-of-the-art label-free semi-quantitative mass-spectrometry method. We observed significant changes in the abundance of several proteins, that fall into two main classes: (i) novel targets for both PCB138 and 180, mediating the dysregulation of CREB pathways and ubiquitin-proteasome system; (ii) different congeners-specific targets (alpha-actinin-1 for PCB138; microtubule-associated-protein-2 for PCB180) that might lead to similar deleterious consequences on neurons cytoskeleton organization. Interference of the PCB congeners with synaptic formation was supported by the increased expression of pre- and post-synaptic proteins quantified by western blot and immunocytochemistry. Expression alteration of synaptic markers was confirmed in the cerebellum of rats developmentally exposed to these congeners, suggesting an adaptive response to neurodevelopmental toxicity on brain structures. As such, our work is expected to lead to new insights into the mechanisms of NDL-PCBs neurotoxicity.
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Affiliation(s)
- Laura Brunelli
- Department of Environmental Health Sciences, Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy
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30
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CaMKII binding to GluN2B is critical during memory consolidation. EMBO J 2012; 31:1203-16. [PMID: 22234183 DOI: 10.1038/emboj.2011.482] [Citation(s) in RCA: 193] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 12/01/2011] [Indexed: 11/08/2022] Open
Abstract
Memory is essential for our normal daily lives and our sense of self. Ca(2+) influx through the NMDA-type glutamate receptor (NMDAR) and the ensuing activation of the Ca(2+) and calmodulin-dependent protein kinase (CaMKII) are required for memory formation and its physiological correlate, long-term potentiation (LTP). The Ca(2+) influx induces CaMKII binding to the NMDAR to strategically recruit CaMKII to synapses that are undergoing potentiation. We generated mice with two point mutations that impair CaMKII binding to the NMDAR GluN2B subunit. Ca(2+)-triggered postsynaptic accumulation is largely abrogated for CaMKII and destabilized for TARPs, which anchor AMPA-type glutamate receptors (AMPAR). LTP is reduced by 50% and phosphorylation of the AMPAR GluA1 subunit by CaMKII, which enhances AMPAR conductance, impaired. The mutant mice learn the Morris water maze (MWM) as well as WT but show deficiency in recall during the period of early memory consolidation. Accordingly, the activity-driven interaction of CaMKII with the NMDAR is important for recall of MWM memory as early as 24 h, but not 1-2 h, after training potentially due to impaired consolidation.
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31
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Lucchesi W, Mizuno K, Giese KP. Novel insights into CaMKII function and regulation during memory formation. Brain Res Bull 2011; 85:2-8. [DOI: 10.1016/j.brainresbull.2010.10.009] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 10/15/2010] [Accepted: 10/29/2010] [Indexed: 01/17/2023]
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32
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Swulius MT, Kubota Y, Forest A, Waxham MN. Structure and composition of the postsynaptic density during development. J Comp Neurol 2011; 518:4243-60. [PMID: 20878786 DOI: 10.1002/cne.22451] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
In this study, we used electron tomography as well as immunogold labeling to analyze the morphology and distribution of proteins within postsynaptic densities (PSDs) isolated from rats before birth (embryonic day 19) and at postnatal days 2, 21, and 60. Our data provide direct evidence of distinct morphological and compositional differences in PSDs throughout development. Not all PSD components are present at the early stages of development, with a near lack of the scaffolding molecule PSD-95 at E19 and P2. The presence of NR1 and NR2b suggests that PSD-95 is not directly required for clustering of N-methyl-D-aspartic acid (NMDA) receptors in PSDs early in development. α-Actinin is abundant by E19, suggesting that it is a core structural component of the PSD. Both α and β isoforms of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) are present early on but then rise in labeling density by approximately fourfold by P21. Among all the molecules studied, only calmodulin (CaM) was found in higher abundance early in PSD development and then fell in amount over time. Spatial analysis of the immunogold label shows a nonrandom distribution for all the proteins studied, lending support to the idea that the PSD is systematically assembled in an organized fashion. Morphological data from electron tomography shows that the PSD undergoes major structural changes throughout development.
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Affiliation(s)
- Matthew T Swulius
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
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Laezza F, Dingledine R. Induction and expression rules of synaptic plasticity in hippocampal interneurons. Neuropharmacology 2010; 60:720-9. [PMID: 21195098 DOI: 10.1016/j.neuropharm.2010.12.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 11/30/2010] [Accepted: 12/15/2010] [Indexed: 12/13/2022]
Abstract
The knowledge that excitatory synapses on aspiny hippocampal interneurons can develop genuine forms of activity-dependent remodeling, independently from the surrounding network of principal cells, is a relatively new concept. Cumulative evidence has now unequivocally demonstrated that, despite the absence of specialized postsynaptic spines that serve as compartmentalized structure for intracellular signaling in principal cell plasticity, excitatory inputs onto interneurons can undergo forms of synaptic plasticity that are induced and expressed autonomously from principal cells. Yet, the rules for induction and expression of interneuron plasticity are much more heterogeneous than in principal neurons. Long-term plasticity in interneurons is not necessarily dependent upon postsynaptic activation of NMDA receptors nor relies on the same postsynaptic membrane potential requirements as principal cells. Plasticity in interneurons rather requires activation of Ca(2+)-permeable AMPA receptors and/or metabotropic glutamate receptors and is triggered by postsynaptic hyperpolarization. In this review we will outline these distinct features of interneuron plasticity and identify potential critical candidate molecules that might be important for sustaining long-lasting changes in synaptic strength at excitatory inputs onto interneurons. This article is part of a Special Issue entitled 'Synaptic Plasticity & Interneurons'.
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Affiliation(s)
- Fernanda Laezza
- University Texas Medical Branch, Department of Pharmacology & Toxicology, 301 University Boulevard, Galveston, TX 77555, USA.
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The DREAM protein negatively regulates the NMDA receptor through interaction with the NR1 subunit. J Neurosci 2010; 30:7575-86. [PMID: 20519532 DOI: 10.1523/jneurosci.1312-10.2010] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Glutamate-induced excitotoxicity has been implicated in the etiology of stroke, epilepsy, and neurodegenerative diseases. NMDA receptors (NMDARs) play a pivotal role in excitotoxic injury; however, clinical trials testing NMDAR antagonists as neuroprotectants have been discouraging. The development of novel neuroprotectant molecules is being vigorously pursued. Here, we report that downstream regulatory element antagonist modulator (DREAM) significantly inhibits surface expression of NMDARs and NMDAR-mediated current. Overexpression of DREAM showed neuroprotection against excitotoxic neuronal injury, whereas knockdown of DREAM enhanced NMDA-induced toxicity. DREAM could directly bind to the C0 domain of the NR1 subunit. Although DREAM contains multiple binding sites for the NR1 subunit, residues 21-40 of the N terminus are the main binding site for the NR1 subunit. Thus, 21-40 residues might relieve the autoinhibition conferred by residues 1-50 and derepress the DREAM core domain by a competitive mechanism. Intriguingly, the cell-permeable TAT-21-40 peptide, constructed according to the critical binding site of DREAM to the NR1 subunit, inhibits NMDAR-mediated currents in primary cultured hippocampal neurons and has a neuroprotective effect on in vitro neuronal excitotoxic injury and in vivo ischemic brain damage. Moreover, both pretreatment and posttreatment of TAT-21-40 is effective against excitotoxicity. In summary, this work reveals a novel, negative regulator of NMDARs and provides an attractive candidate for the treatment of excitotoxicity-related disease.
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Bartos JA, Ulrich JD, Li H, Beazely MA, Chen Y, MacDonald JF, Hell JW. Postsynaptic clustering and activation of Pyk2 by PSD-95. J Neurosci 2010; 30:449-63. [PMID: 20071509 PMCID: PMC2822408 DOI: 10.1523/jneurosci.4992-08.2010] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2008] [Revised: 11/01/2009] [Accepted: 11/04/2009] [Indexed: 12/24/2022] Open
Abstract
The tyrosine kinase Pyk2 plays a unique role in intracellular signal transduction by linking Ca(2+) influx to tyrosine phosphorylation, but the molecular mechanism of Pyk2 activation is unknown. We report that Pyk2 oligomerization by antibodies in vitro or overexpression of PSD-95 in PC6-3 cells induces trans-autophosphorylation of Tyr402, the first step in Pyk2 activation. In neurons, Ca(2+) influx through NMDA-type glutamate receptors causes postsynaptic clustering and autophosphorylation of endogenous Pyk2 via Ca(2+)- and calmodulin-stimulated binding to PSD-95. Accordingly, Ca(2+) influx promotes oligomerization and thereby autoactivation of Pyk2 by stimulating its interaction with PSD-95. We show that this mechanism of Pyk2 activation is critical for long-term potentiation in the hippocampus CA1 region, which is thought to underlie learning and memory.
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Affiliation(s)
- Jason A. Bartos
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242-1109
| | - Jason D. Ulrich
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242-1109
| | - Hongbin Li
- Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada, and
| | - Michael A. Beazely
- Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada, and
| | - Yucui Chen
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242-1109
| | - John F. MacDonald
- Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada, and
- Robarts Research Institute, University of Western Ontario, London, Ontario N6A 5K8, Canada
| | - Johannes W. Hell
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242-1109
- Department of Pharmacology, University of California, Davis, Davis, California 95616-8636
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Ca2+/CaM controls Ca2+-dependent inactivation of NMDA receptors by dimerizing the NR1 C termini. J Neurosci 2008; 28:1865-70. [PMID: 18287503 DOI: 10.1523/jneurosci.5417-07.2008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ca2+ influx through NMDA receptors (NMDARs) leads to channel inactivation, which limits Ca2+ entry and protects against excitotoxicity. Extensive functional data suggests that this Ca2+-dependent inactivation (CDI) requires both calmodulin (CaM) binding to the C0 cassette of the NR1 subunit's C terminus (CT) and regulation by alpha-actinin-2, but a molecular understanding of CDI has been elusive. Here we used a number of methods to analyze the molecular nature of the interaction among CaM, alpha-actinin-2, and the NR1 CT. We found that a single CaM binds to two NR1 CTs in a Ca2+-dependent manner and promotes their reversible "dimerization." Expressed NMDARs containing NR1 concatamers in which the NR1 C termini are "uncoupled" display markedly reduced CDI. In contrast to current models, alpha-actinin-2 does not bind to the NR1 CT. We propose a new model for CDI in which the noncanonical Ca2+/CaM-dependent dimerization of the two NR1 subunits inactivates the channel by propagating a conformational change from the short NR1 CT to the nearby channel pore.
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37
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Age-dependent requirement of AKAP150-anchored PKA and GluR2-lacking AMPA receptors in LTP. EMBO J 2007; 26:4879-90. [PMID: 17972919 DOI: 10.1038/sj.emboj.7601884] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Accepted: 09/19/2007] [Indexed: 11/08/2022] Open
Abstract
Association of PKA with the AMPA receptor GluR1 subunit via the A kinase anchor protein AKAP150 is crucial for GluR1 phosphorylation. Mutating the AKAP150 gene to specifically prevent PKA binding reduced PKA within postsynaptic densities (>70%). It abolished hippocampal LTP in 7-12 but not 4-week-old mice. Inhibitors of PKA and of GluR2-lacking AMPA receptors blocked single tetanus LTP in hippocampal slices of 8 but not 4-week-old WT mice. Inhibitors of GluR2-lacking AMPA receptors also prevented LTP in 2 but not 3-week-old mice. Other studies demonstrate that GluR1 homomeric AMPA receptors are the main GluR2-lacking AMPA receptors in adult hippocampus and require PKA for their functional postsynaptic expression during potentiation. AKAP150-anchored PKA might thus critically contribute to LTP in adult hippocampus in part by phosphorylating GluR1 to foster postsynaptic accumulation of homomeric GluR1 AMPA receptors during initial LTP in 8-week-old mice.
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