101
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Sanderson TM, Hogg EL, Collingridge GL, Corrêa SAL. Hippocampal metabotropic glutamate receptor long-term depression in health and disease: focus on mitogen-activated protein kinase pathways. J Neurochem 2016; 139 Suppl 2:200-214. [PMID: 26923875 DOI: 10.1111/jnc.13592] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 02/16/2016] [Accepted: 02/21/2016] [Indexed: 12/16/2022]
Abstract
Group I metabotropic glutamate receptor (mGluR) dependent long-term depression (LTD) is a major form of synaptic plasticity underlying learning and memory. The molecular mechanisms involved in mGluR-LTD have been investigated intensively for the last two decades. In this 60th anniversary special issue article, we review the recent advances in determining the mechanisms that regulate the induction, transduction and expression of mGluR-LTD in the hippocampus, with a focus on the mitogen-activated protein kinase (MAPK) pathways. In particular we discuss the requirement of p38 MAPK and extracellular signal-regulated kinase 1/2 (ERK 1/2) activation. The recent advances in understanding the signaling cascades regulating mGluR-LTD are then related to the cognitive impairments observed in neurological disorders, such as fragile X syndrome and Alzheimer's disease. mGluR-LTD is a form of synaptic plasticity that impacts on memory formation. In the hippocampus mitogen-activated protein kinases (MAPKs) have been found to be important in mGluR-LTD. In this 60th anniversary special issue article, we review the independent and complementary roles of two classes of MAPK, p38 and ERK1/2 and link this to the aberrant mGluR-LTD that has an important role in diseases. This article is part of the 60th Anniversary special issue.
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Affiliation(s)
- Thomas M Sanderson
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, UK
| | - Ellen L Hogg
- Bradford School of Pharmacy, Faculty of Life Sciences, University of Bradford, Bradford, UK
| | - Graham L Collingridge
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, UK. .,Department of Physiology, University of Toronto, Toronto, Ontario, Canada. .,Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
| | - Sonia A L Corrêa
- Bradford School of Pharmacy, Faculty of Life Sciences, University of Bradford, Bradford, UK.
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102
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Guntupalli S, Widagdo J, Anggono V. Amyloid-β-Induced Dysregulation of AMPA Receptor Trafficking. Neural Plast 2016; 2016:3204519. [PMID: 27073700 PMCID: PMC4814684 DOI: 10.1155/2016/3204519] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 02/28/2016] [Indexed: 01/22/2023] Open
Abstract
Evidence from neuropathological, genetic, animal model, and biochemical studies has indicated that the accumulation of amyloid-beta (Aβ) is associated with, and probably induces, profound neuronal changes in brain regions critical for memory and cognition in the development of Alzheimer's disease (AD). There is considerable evidence that synapses are particularly vulnerable to AD, establishing synaptic dysfunction as one of the earliest events in pathogenesis, prior to neuronal loss. It is clear that excessive Aβ levels can disrupt excitatory synaptic transmission and plasticity, mainly due to dysregulation of the AMPA and NMDA glutamate receptors in the brain. Importantly, AMPA receptors are the principal glutamate receptors that mediate fast excitatory neurotransmission. This is essential for synaptic plasticity, a cellular correlate of learning and memory, which are the cognitive functions that are most disrupted in AD. Here we review recent advances in the field and provide insights into the molecular mechanisms that underlie Aβ-induced dysfunction of AMPA receptor trafficking. This review focuses primarily on NMDA receptor- and metabotropic glutamate receptor-mediated signaling. In particular, we highlight several mechanisms that underlie synaptic long-term depression as common signaling pathways that are hijacked by the neurotoxic effects of Aβ.
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Affiliation(s)
- Sumasri Guntupalli
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jocelyn Widagdo
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Victor Anggono
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
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103
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Bhattacharyya S. Inside story of Group I Metabotropic Glutamate Receptors (mGluRs). Int J Biochem Cell Biol 2016; 77:205-12. [PMID: 26987586 DOI: 10.1016/j.biocel.2016.03.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 03/10/2016] [Accepted: 03/11/2016] [Indexed: 12/31/2022]
Abstract
Metabotropic glutamate receptors (mGluRs) are G-protein coupled receptors (GPCRs) that are activated by the neurotransmitter glutamate in the central nervous system. Among the eight subtypes, mGluR1 and mGluR5 belong to the group I family. These receptors play important roles in the brain and are believed to be involved in multiple forms of experience dependent synaptic plasticity including learning and memory. In addition, group I mGluRs also have been implicated in various neuropsychiatric disorders like Fragile X syndrome, autism etc. The normal signaling depends on the precise location of these receptors in specific region of the neuron and the process of receptor trafficking plays a crucial role in controlling this localization. Intracellular trafficking could also regulate the desensitization, resensitization, down-regulation and intracellular signaling of these receptors. In this review I focus on the current understanding of group I mGluR regulation in the central nervous system and also their role in neuropsychiatric disorders.
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Affiliation(s)
- Samarjit Bhattacharyya
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge city, Sector-81, SAS Nagar, PO: 140306, Punjab, India.
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104
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CPG2 Recruits Endophilin B2 to the Cytoskeleton for Activity-Dependent Endocytosis of Synaptic Glutamate Receptors. Curr Biol 2016; 26:296-308. [PMID: 26776730 DOI: 10.1016/j.cub.2015.11.071] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 09/21/2015] [Accepted: 11/30/2015] [Indexed: 11/23/2022]
Abstract
Internalization of glutamate receptors at the postsynaptic membrane via clathrin-mediated endocytosis (CME) is a key mechanism for regulating synaptic strength. A role for the F-actin cytoskeleton in CME is well established, and recently, PKA-dependent association of candidate plasticity gene 2 (CPG2) with the spine-cytoskeleton has been shown to mediate synaptic glutamate receptor internalization. Yet, how the endocytic machinery is physically coupled to the actin cytoskeleton to facilitate glutamate receptor internalization has not been demonstrated. Moreover, there has been no distinction of endocytic-machinery components that are specific to activity-dependent versus constitutive glutamate receptor internalization. Here, we show that CPG2, through a direct physical interaction, recruits endophilin B2 (EndoB2) to F-actin, thus anchoring the endocytic machinery to the spine cytoskeleton and facilitating glutamate receptor internalization. Regulation of CPG2 binding to the actin cytoskeleton by protein kinase A directly impacts recruitment of EndoB2 and clathrin. Specific disruption of EndoB2 or the CPG2-EndoB2 interaction impairs activity-dependent, but not constitutive, internalization of both NMDA- and AMPA-type glutamate receptors. These results demonstrate that, through direct interactions with F-actin and EndoB2, CPG2 physically bridges the spine cytoskeleton and the endocytic machinery, and this tripartite association is critical specifically for activity-dependent CME of synaptic glutamate receptors.
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105
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Potentiation of M1 Muscarinic Receptor Reverses Plasticity Deficits and Negative and Cognitive Symptoms in a Schizophrenia Mouse Model. Neuropsychopharmacology 2016; 41:598-610. [PMID: 26108886 PMCID: PMC5130135 DOI: 10.1038/npp.2015.189] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Revised: 06/09/2015] [Accepted: 06/11/2015] [Indexed: 01/13/2023]
Abstract
Schizophrenia patients exhibit deficits in signaling of the M1 subtype of muscarinic acetylcholine receptor (mAChR) in the prefrontal cortex (PFC) and also display impaired cortical long-term depression (LTD). We report that selective activation of the M1 mAChR subtype induces LTD in PFC and that this response is completely lost after repeated administration of phencyclidine (PCP), a mouse model of schizophrenia. Furthermore, discovery of a novel, systemically active M1 positive allosteric modulator (PAM), VU0453595, allowed us to evaluate the impact of selective potentiation of M1 on induction of LTD and behavioral deficits in PCP-treated mice. Interestingly, VU0453595 fully restored impaired LTD as well as deficits in cognitive function and social interaction in these mice. These results provide critical new insights into synaptic changes that may contribute to behavioral deficits in this mouse model and support a role for selective M1 PAMs as a novel approach for the treatment of schizophrenia.
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106
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Borovok N, Nesher E, Levin Y, Reichenstein M, Pinhasov A, Michaelevski I. Dynamics of Hippocampal Protein Expression During Long-term Spatial Memory Formation. Mol Cell Proteomics 2015; 15:523-41. [PMID: 26598641 DOI: 10.1074/mcp.m115.051318] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Indexed: 01/08/2023] Open
Abstract
Spatial memory depends on the hippocampus, which is particularly vulnerable to aging. This vulnerability has implications for the impairment of navigation capacities in older people, who may show a marked drop in performance of spatial tasks with advancing age. Contemporary understanding of long-term memory formation relies on molecular mechanisms underlying long-term synaptic plasticity. With memory acquisition, activity-dependent changes occurring in synapses initiate multiple signal transduction pathways enhancing protein turnover. This enhancement facilitates de novo synthesis of plasticity related proteins, crucial factors for establishing persistent long-term synaptic plasticity and forming memory engrams. Extensive studies have been performed to elucidate molecular mechanisms of memory traces formation; however, the identity of plasticity related proteins is still evasive. In this study, we investigated protein turnover in mouse hippocampus during long-term spatial memory formation using the reference memory version of radial arm maze (RAM) paradigm. We identified 1592 proteins, which exhibited a complex picture of expression changes during spatial memory formation. Variable linear decomposition reduced significantly data dimensionality and enriched three principal factors responsible for variance of memory-related protein levels at (1) the initial phase of memory acquisition (165 proteins), (2) during the steep learning improvement (148 proteins), and (3) the final phase of the learning curve (123 proteins). Gene ontology and signaling pathways analysis revealed a clear correlation between memory improvement and learning phase-curbed expression profiles of proteins belonging to specific functional categories. We found differential enrichment of (1) neurotrophic factors signaling pathways, proteins regulating synaptic transmission, and actin microfilament during the first day of the learning curve; (2) transcription and translation machinery, protein trafficking, enhancement of metabolic activity, and Wnt signaling pathway during the steep phase of memory formation; and (3) cytoskeleton organization proteins. Taken together, this study clearly demonstrates dynamic assembly and disassembly of protein-protein interaction networks depending on the stage of memory formation engrams.
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Affiliation(s)
- Natalia Borovok
- From the ‡Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv 6997801, Israel
| | - Elimelech Nesher
- §Department of Molecular Biology, Ariel University, Ariel 4070000, Israel
| | - Yishai Levin
- ¶de Botton Institute for Protein Profiling, The Nancy & Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Michal Reichenstein
- From the ‡Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv 6997801, Israel
| | - Albert Pinhasov
- §Department of Molecular Biology, Ariel University, Ariel 4070000, Israel
| | - Izhak Michaelevski
- From the ‡Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv 6997801, Israel; ‖Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
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107
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Fang XQ, Qiao H, Groveman BR, Feng S, Pflueger M, Xin WK, Ali MK, Lin SX, Xu J, Duclot F, Kabbaj M, Wang W, Ding XS, Santiago-Sim T, Jiang XH, Salter MW, Yu XM. Regulated internalization of NMDA receptors drives PKD1-mediated suppression of the activity of residual cell-surface NMDA receptors. Mol Brain 2015; 8:75. [PMID: 26584860 PMCID: PMC4653853 DOI: 10.1186/s13041-015-0167-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 11/13/2015] [Indexed: 12/13/2022] Open
Abstract
Background Constitutive and regulated internalization of cell surface proteins has been extensively investigated. The regulated internalization has been characterized as a principal mechanism for removing cell-surface receptors from the plasma membrane, and signaling to downstream targets of receptors. However, so far it is still not known whether the functional properties of remaining (non-internalized) receptor/channels may be regulated by internalization of the same class of receptor/channels. The N-methyl-D-aspartate receptor (NMDAR) is a principal subtype of glutamate-gated ion channel and plays key roles in neuronal plasticity and memory functions. NMDARs are well-known to undergo two types of regulated internalization – homologous and heterologous, which can be induced by high NMDA/glycine and DHPG, respectively. In the present work, we investigated effects of regulated NMDAR internalization on the activity of residual cell-surface NMDARs and neuronal functions. Results In electrophysiological experiments we discovered that the regulated internalization of NMDARs not only reduced the number of cell surface NMDARs but also caused an inhibition of the activity of remaining (non-internalized) surface NMDARs. In biochemical experiments we identified that this functional inhibition of remaining surface NMDARs was mediated by increased serine phosphorylation of surface NMDARs, resulting from the activation of protein kinase D1 (PKD1). Knockdown of PKD1 did not affect NMDAR internalization but prevented the phosphorylation and inhibition of remaining surface NMDARs and NMDAR-mediated synaptic functions. Conclusion These data demonstrate a novel concept that regulated internalization of cell surface NMDARs not only reduces the number of NMDARs on the cell surface but also causes an inhibition of the activity of remaining surface NMDARs through intracellular signaling pathway(s). Furthermore, modulating the activity of remaining surface receptors may be an effective approach for treating receptor internalization-induced changes in neuronal functions of the CNS. Electronic supplementary material The online version of this article (doi:10.1186/s13041-015-0167-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xiao-Qian Fang
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, 32306, USA.
| | - Haifa Qiao
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, 32306, USA.
| | - Bradley R Groveman
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, 32306, USA.
| | - Shuang Feng
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, 32306, USA.
| | - Melissa Pflueger
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, 32306, USA.
| | - Wen-Kuan Xin
- Faculty of Dentistry, University of Toronto, Toronto, M5G 1G6, Canada.
| | - Mohammad K Ali
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, 32306, USA.
| | - Shuang-Xiu Lin
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, 32306, USA.
| | - Jindong Xu
- Faculty of Dentistry, University of Toronto, Toronto, M5G 1G6, Canada.
| | - Florian Duclot
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, 32306, USA.
| | - Mohamed Kabbaj
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, 32306, USA.
| | - Wei Wang
- Department of Neurology, 1st Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, PR China.
| | - Xin-Sheng Ding
- Department of Neurology, 1st Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, PR China. .,BenQ Neurological Institute, Nanjing Medical University, Nanjing, 210021, PR China.
| | - Teresa Santiago-Sim
- Department of Neurosurgery, The University of Texas Medical School at Houston Vivian L. Smith, Houston, TX, 77030, USA.
| | - Xing-Hong Jiang
- Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou, 215123, China.
| | - Michael W Salter
- Program in Neuroscience and Mental Health, Hospital for Sick Children, University of Toronto, Toronto, M5G 1X8, Canada.
| | - Xian-Min Yu
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, 32306, USA. .,Faculty of Dentistry, University of Toronto, Toronto, M5G 1G6, Canada. .,BenQ Neurological Institute, Nanjing Medical University, Nanjing, 210021, PR China. .,Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou, 215123, China.
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108
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Köles L, Kató E, Hanuska A, Zádori ZS, Al-Khrasani M, Zelles T, Rubini P, Illes P. Modulation of excitatory neurotransmission by neuronal/glial signalling molecules: interplay between purinergic and glutamatergic systems. Purinergic Signal 2015; 12:1-24. [PMID: 26542977 DOI: 10.1007/s11302-015-9480-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/26/2015] [Indexed: 12/29/2022] Open
Abstract
Glutamate is the main excitatory neurotransmitter of the central nervous system (CNS), released both from neurons and glial cells. Acting via ionotropic (NMDA, AMPA, kainate) and metabotropic glutamate receptors, it is critically involved in essential regulatory functions. Disturbances of glutamatergic neurotransmission can be detected in cognitive and neurodegenerative disorders. This paper summarizes the present knowledge on the modulation of glutamate-mediated responses in the CNS. Emphasis will be put on NMDA receptor channels, which are essential executive and integrative elements of the glutamatergic system. This receptor is crucial for proper functioning of neuronal circuits; its hypofunction or overactivation can result in neuronal disturbances and neurotoxicity. Somewhat surprisingly, NMDA receptors are not widely targeted by pharmacotherapy in clinics; their robust activation or inhibition seems to be desirable only in exceptional cases. However, their fine-tuning might provide a promising manipulation to optimize the activity of the glutamatergic system and to restore proper CNS function. This orchestration utilizes several neuromodulators. Besides the classical ones such as dopamine, novel candidates emerged in the last two decades. The purinergic system is a promising possibility to optimize the activity of the glutamatergic system. It exerts not only direct and indirect influences on NMDA receptors but, by modulating glutamatergic transmission, also plays an important role in glia-neuron communication. These purinergic functions will be illustrated mostly by depicting the modulatory role of the purinergic system on glutamatergic transmission in the prefrontal cortex, a CNS area important for attention, memory and learning.
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Affiliation(s)
- László Köles
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, Semmelweis University, Nagyvárad tér 4, Budapest, 1089, Hungary.
| | - Erzsébet Kató
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, Semmelweis University, Nagyvárad tér 4, Budapest, 1089, Hungary
| | - Adrienn Hanuska
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, Semmelweis University, Nagyvárad tér 4, Budapest, 1089, Hungary
| | - Zoltán S Zádori
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, Semmelweis University, Nagyvárad tér 4, Budapest, 1089, Hungary
| | - Mahmoud Al-Khrasani
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, Semmelweis University, Nagyvárad tér 4, Budapest, 1089, Hungary
| | - Tibor Zelles
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, Semmelweis University, Nagyvárad tér 4, Budapest, 1089, Hungary
| | - Patrizia Rubini
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, 04107, Leipzig, Germany
| | - Peter Illes
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, 04107, Leipzig, Germany.
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109
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Banks PJ, Burroughs AC, Barker GRI, Brown JT, Warburton EC, Bashir ZI. Disruption of hippocampal-prefrontal cortex activity by dopamine D2R-dependent LTD of NMDAR transmission. Proc Natl Acad Sci U S A 2015; 112:11096-101. [PMID: 26286993 PMCID: PMC4568284 DOI: 10.1073/pnas.1512064112] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Functional connectivity between the hippocampus and prefrontal cortex (PFC) is essential for associative recognition memory and working memory. Disruption of hippocampal-PFC synchrony occurs in schizophrenia, which is characterized by hypofunction of NMDA receptor (NMDAR)-mediated transmission. We demonstrate that activity of dopamine D2-like receptors (D2Rs) leads selectively to long-term depression (LTD) of hippocampal-PFC NMDAR-mediated synaptic transmission. We show that dopamine-dependent LTD of NMDAR-mediated transmission profoundly disrupts normal synaptic transmission between hippocampus and PFC. These results show how dopaminergic activation induces long-term hypofunction of NMDARs, which can contribute to disordered functional connectivity, a characteristic that is a hallmark of psychiatric disorders such as schizophrenia.
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Affiliation(s)
- Paul James Banks
- School of Physiology and Pharmacology, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | | | | | - Jon Thomas Brown
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, EX4 4PS, United Kingdom
| | | | - Zafar Iqbal Bashir
- School of Physiology and Pharmacology, University of Bristol, Bristol, BS8 1TD, United Kingdom;
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110
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Li Y, Pehrson AL, Waller JA, Dale E, Sanchez C, Gulinello M. A critical evaluation of the activity-regulated cytoskeleton-associated protein (Arc/Arg3.1)'s putative role in regulating dendritic plasticity, cognitive processes, and mood in animal models of depression. Front Neurosci 2015; 9:279. [PMID: 26321903 PMCID: PMC4530346 DOI: 10.3389/fnins.2015.00279] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 07/23/2015] [Indexed: 11/13/2022] Open
Abstract
Major depressive disorder (MDD) is primarily conceptualized as a mood disorder but cognitive dysfunction is also prevalent, and may limit the daily function of MDD patients. Current theories on MDD highlight disturbances in dendritic plasticity in its pathophysiology, which could conceivably play a role in the production of both MDD-related mood and cognitive symptoms. This paper attempts to review the accumulated knowledge on the basic biology of the activity-regulated cytoskeleton-associated protein (Arc or Arg3.1), its effects on neural plasticity, and how these may be related to mood or cognitive dysfunction in animal models of MDD. On a cellular level, Arc plays an important role in modulating dendritic spine density and remodeling. Arc also has a close, bidirectional relationship with postsynaptic glutamate neurotransmission, since it is stimulated by multiple glutamatergic receptor mechanisms but also modulates α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor internalization. The effects on AMPA receptor trafficking are likely related to Arc's ability to modulate phenomena such as long-term potentiation, long-term depression, and synaptic scaling, each of which are important for maintaining proper cognitive function. Chronic stress models of MDD in animals show suppressed Arc expression in the frontal cortex but elevation in the amygdala. Interestingly, cognitive tasks depending on the frontal cortex are generally impaired by chronic stress, while those depending on the amygdala are enhanced, and antidepressant treatments stimulate cortical Arc expression with a timeline that is reminiscent of the treatment efficacy lag observed in the clinic or in preclinical models. However, pharmacological treatments that stimulate regional Arc expression do not universally improve relevant cognitive functions, and this highlights a need to further refine our understanding of Arc on a subcellular and network level.
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Affiliation(s)
- Yan Li
- External Sourcing and Scientific Excellence, Lundbeck Research USA, Inc. Paramus, NJ, USA
| | - Alan L Pehrson
- External Sourcing and Scientific Excellence, Lundbeck Research USA, Inc. Paramus, NJ, USA
| | - Jessica A Waller
- External Sourcing and Scientific Excellence, Lundbeck Research USA, Inc. Paramus, NJ, USA
| | - Elena Dale
- Neuroinflammation Disease Biology Unit, Lundbeck Research USA, Inc. Paramus, NJ, USA
| | - Connie Sanchez
- External Sourcing and Scientific Excellence, Lundbeck Research USA, Inc. Paramus, NJ, USA
| | - Maria Gulinello
- Behavioral Core Facility, Department of Neuroscience, Albert Einstein College of Medicine Bronx, NY, USA
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111
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Jin DZ, Xue B, Mao LM, Wang JQ. Metabotropic glutamate receptor 5 upregulates surface NMDA receptor expression in striatal neurons via CaMKII. Brain Res 2015; 1624:414-423. [PMID: 26256252 DOI: 10.1016/j.brainres.2015.07.053] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 07/23/2015] [Accepted: 07/30/2015] [Indexed: 12/29/2022]
Abstract
Metabotropic and ionotropic glutamate receptors are closely clustered in postsynaptic membranes and are believed to interact actively with each other to control excitatory synaptic transmission. Metabotropic glutamate receptor 5 (mGluR5), for example, has been well documented to potentiate ionotropic NMDA receptor activity, although underlying mechanisms are poorly understood. In this study, we investigated the role of mGluR5 in regulating trafficking and subcellular distribution of NMDA receptors in adult rat striatal neurons. We found that the mGluR1/5 agonist DHPG concentration-dependently increased NMDA receptor GluN1 and GluN2B subunit expression in the surface membrane. Meanwhile, DHPG reduced GluN1 and GluN2B levels in the intracellular compartment. The effect of DHPG was blocked by an mGluR5 selective antagonist MTEP but not by an mGluR1 selective antagonist 3-MATIDA. Pretreatment with an inhibitor or a specific inhibitory peptide for synapse-enriched Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) also blocked the DHPG-stimulated redistribution of GluN1 and GluN2B. In addition, DHPG enhanced CaMKIIα activity and elevated GluN2B phosphorylation at a CaMKII-sensitive site (serine 1303). These results demonstrate that mGluR5 regulates trafficking of NMDA receptors in striatal neurons. Activation of mGluR5 appears to induce rapid trafficking of GluN1 and GluN2B to surface membranes through a signaling pathway involving CaMKII.
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Affiliation(s)
- Dao-Zhong Jin
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Bing Xue
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Li-Min Mao
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - John Q Wang
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA; Department of Anesthesiology, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA.
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112
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Olde Loohuis NFM, Ba W, Stoerchel PH, Kos A, Jager A, Schratt G, Martens GJM, van Bokhoven H, Nadif Kasri N, Aschrafi A. MicroRNA-137 Controls AMPA-Receptor-Mediated Transmission and mGluR-Dependent LTD. Cell Rep 2015; 11:1876-84. [PMID: 26095359 DOI: 10.1016/j.celrep.2015.05.040] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 04/13/2015] [Accepted: 05/26/2015] [Indexed: 10/23/2022] Open
Abstract
Mutations affecting the levels of microRNA miR-137 are associated with intellectual disability and schizophrenia. However, the pathophysiological role of miR-137 remains poorly understood. Here, we describe a highly conserved miR-137-binding site within the mRNA encoding the GluA1 subunit of AMPA-type glutamate receptors (AMPARs) and confirm that GluA1 is a direct target of miR-137. Postsynaptic downregulation of miR-137 at the CA3-CA1 hippocampal synapse selectively enhances AMPAR-mediated synaptic transmission and converts silent synapses to active synapses. Conversely, miR-137 overexpression selectively reduces AMPAR-mediated synaptic transmission and silences active synapses. In addition, we find that miR-137 is transiently upregulated in response to metabotropic glutamate receptor 5 (mGluR5), but not mGluR1 activation. Consequently, acute interference with miR-137 function impedes mGluR-LTD expression. Our findings suggest that miR-137 is a key factor in the control of synaptic efficacy and mGluR-dependent synaptic plasticity, supporting the notion that glutamatergic dysfunction contributes to the pathogenesis of miR-137-linked cognitive impairments.
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Affiliation(s)
- Nikkie F M Olde Loohuis
- Department of Cognitive Neuroscience, Radboudumc, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, 6525 AJ Nijmegen, the Netherlands
| | - Wei Ba
- Department of Human Genetics, Radboudumc, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, 6525 AJ Nijmegen, the Netherlands
| | - Peter H Stoerchel
- Institute of Physiological Chemistry, Biochemical-Pharmacological Center Marburg, Philipps University Marburg, 35032 Marburg, Germany
| | - Aron Kos
- Department of Cognitive Neuroscience, Radboudumc, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, 6525 AJ Nijmegen, the Netherlands
| | - Amanda Jager
- Department of Cognitive Neuroscience, Radboudumc, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, 6525 AJ Nijmegen, the Netherlands
| | - Gerhard Schratt
- Institute of Physiological Chemistry, Biochemical-Pharmacological Center Marburg, Philipps University Marburg, 35032 Marburg, Germany
| | - Gerard J M Martens
- Department of Molecular Animal Physiology, Radboud University Nijmegen, 6525 HP Nijmegen, the Netherlands; Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, 6525 AJ Nijmegen, the Netherlands
| | - Hans van Bokhoven
- Department of Cognitive Neuroscience, Radboudumc, 6500 HB Nijmegen, the Netherlands; Department of Human Genetics, Radboudumc, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, 6525 AJ Nijmegen, the Netherlands
| | - Nael Nadif Kasri
- Department of Cognitive Neuroscience, Radboudumc, 6500 HB Nijmegen, the Netherlands; Department of Human Genetics, Radboudumc, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, 6525 AJ Nijmegen, the Netherlands.
| | - Armaz Aschrafi
- Department of Neuroinformatics, Radboud University Nijmegen, 6525 HP Nijmegen, the Netherlands; Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, 6525 AJ Nijmegen, the Netherlands.
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Hu Z, Zhao J, Hu T, Luo Y, Zhu J, Li Z. miR-501-3p mediates the activity-dependent regulation of the expression of AMPA receptor subunit GluA1. ACTA ACUST UNITED AC 2015; 208:949-59. [PMID: 25800054 PMCID: PMC4384731 DOI: 10.1083/jcb.201404092] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The number of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) in synapses determines synaptic strength. AMPAR expression can be regulated locally in dendrites by synaptic activity. The mechanisms of activity-dependent local regulation of AMPAR expression, however, remain unclear. Here, we tested whether microRNAs (miRNAs) are involved in N-methyl-D-aspartate (NMDA) receptor (NMDAR)-dependent AMPAR expression. We used the 3' untranslated region of Gria1, which encodes the AMPA receptor subunit GluA1, to pull down miRNAs binding to it and analyzed these miRNAs using next-generation deep sequencing. Among the identified miRNAs, miR-501-3p is also a computationally predicted Gria1-targeting miRNA. We confirmed that miR-501-3p targets Gria1 and regulates its expression under physiological conditions. The expression of miR-501-3p and GluA1, moreover, is inversely correlated during postnatal brain development. miR-501-3p expression is up-regulated locally in dendrites through the NMDAR subunit GluN2A, and this regulation is required for NMDA-induced suppression of GluA1 expression and long-lasting remodeling of dendritic spines. These findings elucidate a miRNA-mediated mechanism for activity-dependent, local regulation of AMPAR expression in dendrites.
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Affiliation(s)
- Zhonghua Hu
- Unit on Synapse Development and Plasticity, National Institute of Mental Health, and Genetics and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Jun Zhao
- Unit on Synapse Development and Plasticity, National Institute of Mental Health, and Genetics and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Tianyi Hu
- Unit on Synapse Development and Plasticity, National Institute of Mental Health, and Genetics and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Yan Luo
- Unit on Synapse Development and Plasticity, National Institute of Mental Health, and Genetics and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Jun Zhu
- Unit on Synapse Development and Plasticity, National Institute of Mental Health, and Genetics and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Zheng Li
- Unit on Synapse Development and Plasticity, National Institute of Mental Health, and Genetics and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
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114
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Abstract
Fragile X syndrome (FXS) is one of the major causes for autism and mental retardation in humans. The etiology of FXS is linked to the expansion of the CGG trinucleotide repeats, r(CGG), suppressing the fragile X mental retardation 1 (FMR1) gene on the X chromosome, resulting in a loss of fragile X mental retardation protein (FMRP) expression, which is required for regulating normal neuronal connectivity and plasticity. Recent studies have further identified that microRNAs are involved in the mechanisms underlying FXS pathogenesis at three different developmental stages. During early embryogenesis before the blastocyst stage, an embryonic stem cell (ESC)-specific microRNA, miR-302, interferes with FMR1 mRNA translation to maintain the stem cell status and inhibit neural development. After blastocyst, the downregulation of miR-302 releases FMRP synthesis and subsequently leads to neuronal development; yet, in FXS, certain r(CGG)-derived microRNAs, such as miR-fmr1s, are expressed and accumulated and then induce DNA hypermethylation on the FMR1 gene promoter regions, resulting in transcriptional inactivation of the FMR1 gene and the loss of FMRP. In normal neuronal development, FMRP is an RNA-binding protein responsible for interacting with miR-125 and miR-132 to regulate the signaling of Group 1 metabotropic glutamate receptor (mGluR1) and N-methyl-D-aspartate receptor (NMDAR), respectively, and consequently affecting synaptic plasticity. As a result, the loss of FMRP impairs these signaling controls and eventually causes FXS-associated disorders, such as autism and mental retardation. Based on these current findings, this chapter will summarize the etiological causes of FXS and further provides significant insights into the molecular mechanisms underlying microRNA-mediated FXS pathogenesis and the related therapy development.
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115
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Masuoka T, Nakamura T, Kudo M, Yoshida J, Takaoka Y, Kato N, Ishibashi T, Imaizumi N, Nishio M. Biphasic modulation by mGlu5 receptors of TRPV1-mediated intracellular calcium elevation in sensory neurons contributes to heat sensitivity. Br J Pharmacol 2014; 172:1020-33. [PMID: 25297838 DOI: 10.1111/bph.12962] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 09/15/2014] [Accepted: 09/26/2014] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Elevation of glutamate, an excitatory amino acid, during inflammation and injury plays a crucial role in the reception and transmission of sensory information via ionotropic and metabotropic receptors. This study aimed to investigate the mechanisms underlying the biphasic effects of metabotropic glutamate mGlu5 receptor activation on responses to noxious heat. EXPERIMENTAL APPROACH We assessed the effects of intraplantar quisqualate, a non-selective glutamate receptor agonist, on heat and mechanical pain behaviours in mice. In addition, the effects of quisqualate on the intracellular calcium response and on membrane currents mediated by TRPV1 channels, were examined in cultured dorsal root ganglion neurons from mice. KEY RESULTS Activation of mGlu5 receptors in hind paw transiently increased, then decreased, the response to noxious heat. In sensory neurons, activation of mGlu5 receptors potentiated TRPV1-mediated intracellular calcium elevation, while terminating activation of mGlu5 receptors depressed it. TRPV1-induced currents were potentiated by activation of mGlu5 receptors under voltage clamp conditions and these disappeared after washout. However, voltage-gated calcium currents were inhibited by the mGlu5 receptor agonist, even after washout. CONCLUSIONS AND IMPLICATIONS These results suggest that, in sensory neurons, mGlu5 receptors biphasically modulate TRPV1-mediated intracellular calcium response via transient potentiation of TRPV1 channel-induced currents and persistent inhibition of voltage-gated calcium currents, contributing to heat hyper- and hypoalgesia.
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Affiliation(s)
- T Masuoka
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Japan
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116
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Karasawa T, Lombroso PJ. Disruption of striatal-enriched protein tyrosine phosphatase (STEP) function in neuropsychiatric disorders. Neurosci Res 2014; 89:1-9. [PMID: 25218562 DOI: 10.1016/j.neures.2014.08.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 08/12/2014] [Accepted: 08/21/2014] [Indexed: 10/24/2022]
Abstract
Striatal-enriched protein tyrosine phosphatase (STEP) is a brain-specific tyrosine phosphatase that plays a major role in the development of synaptic plasticity. Recent findings have implicated STEP in several psychiatric and neurological disorders, including Alzheimer's disease, schizophrenia, fragile X syndrome, Huntington's disease, stroke/ischemia, and stress-related psychiatric disorders. In these disorders, STEP protein expression levels and activity are dysregulated, contributing to the cognitive deficits that are present. In this review, we focus on the most recent findings on STEP, discuss how STEP expression and activity are maintained during normal cognitive function, and how disruptions in STEP activity contribute to a number of illnesses.
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Affiliation(s)
- Takatoshi Karasawa
- Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi 480-0392, Japan.
| | - Paul J Lombroso
- Departments of Neurobiology, Psychiatry and Child Study Center, Yale University School of Medicine, New Haven, CT 06520, USA
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117
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Di Prisco GV, Huang W, Buffington SA, Hsu CC, Bonnen PE, Placzek AN, Sidrauski C, Krnjević K, Kaufman RJ, Walter P, Costa-Mattioli M. Translational control of mGluR-dependent long-term depression and object-place learning by eIF2α. Nat Neurosci 2014; 17:1073-82. [PMID: 24974795 DOI: 10.1038/nn.3754] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 05/30/2014] [Indexed: 02/06/2023]
Abstract
At hippocampal synapses, activation of group I metabotropic glutamate receptors (mGluRs) induces long-term depression (LTD), which requires new protein synthesis. However, the underlying mechanism remains elusive. Here we describe the translational program that underlies mGluR-LTD and identify the translation factor eIF2α as its master effector. Genetically reducing eIF2α phosphorylation, or specifically blocking the translation controlled by eIF2α phosphorylation, prevented mGluR-LTD and the internalization of surface AMPA receptors (AMPARs). Conversely, direct phosphorylation of eIF2α, bypassing mGluR activation, triggered a sustained LTD and removal of surface AMPARs. Combining polysome profiling and RNA sequencing, we identified the mRNAs translationally upregulated during mGluR-LTD. Translation of one of these mRNAs, oligophrenin-1, mediates the LTD induced by eIF2α phosphorylation. Mice deficient in phospho-eIF2α-mediated translation are impaired in object-place learning, a behavioral task that induces hippocampal mGluR-LTD in vivo. Our findings identify a new model of mGluR-LTD, which promises to be of value in the treatment of mGluR-LTD-linked cognitive disorders.
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Affiliation(s)
- Gonzalo Viana Di Prisco
- 1] Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA. [2] Memory and Brain Research Center, Baylor College of Medicine, Houston, Texas, USA. [3]
| | - Wei Huang
- 1] Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA. [2] Memory and Brain Research Center, Baylor College of Medicine, Houston, Texas, USA. [3]
| | - Shelly A Buffington
- 1] Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA. [2] Memory and Brain Research Center, Baylor College of Medicine, Houston, Texas, USA. [3]
| | - Chih-Chun Hsu
- 1] Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA. [2] Memory and Brain Research Center, Baylor College of Medicine, Houston, Texas, USA
| | - Penelope E Bonnen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Andon N Placzek
- 1] Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA. [2] Present address: Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, Georgia, USA
| | - Carmela Sidrauski
- Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California San Francisco, San Francisco, California, USA
| | - Krešimir Krnjević
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Randal J Kaufman
- Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, California, USA
| | - Peter Walter
- Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California San Francisco, San Francisco, California, USA
| | - Mauro Costa-Mattioli
- 1] Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA. [2] Memory and Brain Research Center, Baylor College of Medicine, Houston, Texas, USA
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mGluR5 Upregulation increases excitability of hypothalamic presympathetic neurons through NMDA receptor trafficking in spontaneously hypertensive rats. J Neurosci 2014; 34:4309-17. [PMID: 24647951 DOI: 10.1523/jneurosci.4295-13.2014] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The hypothalamic paraventricular nucleus (PVN) is critically involved in elevated sympathetic output and the development of hypertension. However, changes in group I metabotropic glutamate receptors (mGluR1 and mGluR5) and their relevance to the hyperactivity of PVN presympathetic neurons in hypertension remain unclear. Here, we found that selectively blocking mGluR5 significantly reduced the basal firing activity of spinally projecting PVN neurons in spontaneously hypertensive rats (SHRs), but not in normotensive Wistar-Kyoto (WKY) rats. However, blocking mGluR1 had no effect on the firing activity of PVN neurons in either group. The mRNA and protein levels of mGluR5 in the PVN and rostral ventrolateral medulla were significantly higher in SHRs than in WKY rats. The group I mGluR selective agonist (S)-3,5-dihydroxyphenylglycine (DHPG) similarly increased the firing activity of PVN neurons in WKY rats and SHRs. In addition, blocking NMDA receptors (NMDARs) through bath application or intracellular dialysis not only decreased the basal firing in SHRs, but also eliminated DHPG-induced excitation of spinally projecting PVN neurons. DHPG significantly increased the amplitude of NMDAR currents without changing their decay kinetics. Interestingly, DHPG still increased the amplitude of NMDAR currents and caused reappearance of functional NMDAR channels after initially blocking NMDARs. In addition, protein kinase C (PKC) inhibition or intracellular dialysis with synaptosomal-associated protein of 25 kDa (SNAP-25)-blocking peptide abolished DHPG-induced increases in NMDAR currents of PVN neurons in SHRs. Our findings suggest that mGluR5 in the PVN is upregulated in hypertension and contributes to the hyperactivity of PVN presympathetic neurons through PKC- and SNAP-25-mediated surface expression of NMDARs.
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Gandhi RM, Kogan CS, Messier C. 2-Methyl-6-(phenylethynyl) pyridine (MPEP) reverses maze learning and PSD-95 deficits in Fmr1 knock-out mice. Front Cell Neurosci 2014; 8:70. [PMID: 24701200 PMCID: PMC3965849 DOI: 10.3389/fncel.2014.00070] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Accepted: 02/17/2014] [Indexed: 11/22/2022] Open
Abstract
Fragile X Syndrome (FXS) is caused by the lack of expression of the fragile X mental retardation protein (FMRP), which results in intellectual disability and other debilitating symptoms including impairment of visual-spatial functioning. FXS is the only single-gene disorder that is highly co-morbid with autism spectrum disorder and can therefore provide insight into its pathophysiology. Lack of FMRP results in altered group I metabotropic glutamate receptor (mGluR) signaling, which is a target for putative treatments. The Hebb-Williams (H-W) mazes are a set of increasingly complex spatial navigation problems that depend on intact hippocampal and thus mGluR-5 functioning. In the present investigation, we examined whether an antagonist of mGluR-5 would reverse previously described behavioral deficits in fragile X mental retardation 1 knock-out (Fmr1 KO) mice. Mice were trained on a subset of the H-W mazes and then treated with either 20 mg/kg of an mGluR-5 antagonist, 2-Methyl-6-(phenylethynyl) pyridine (MPEP; n = 11) or an equivalent dose of saline (n = 11) prior to running test mazes. Latency and errors were dependent variables recorded during the test phase. Immediately after completing each test, marble-burying behavior was assessed, which confirmed that the drug treatment was pharmacologically active during maze learning. Although latency was not statistically different between the groups, MPEP treated Fmr1 KO mice made significantly fewer errors on mazes deemed more difficult suggesting a reversal of the behavioral deficit. MPEP treated mice were also less perseverative and impulsive when navigating mazes. Furthermore, MPEP treatment reversed post-synaptic density-95 (PSD-95) protein deficits in Fmr1 KO treated mice, whereas levels of a control protein (β-tubulin) remained unchanged. These data further validate MPEP as a potentially beneficial treatment for FXS. Our findings also suggest that adapted H-W mazes may be a useful tool to document alterations in behavioral functioning following pharmacological intervention in FXS.
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Affiliation(s)
- Réno M Gandhi
- School of Psychology, University of Ottawa Ottawa, ON, Canada
| | - Cary S Kogan
- School of Psychology, University of Ottawa Ottawa, ON, Canada
| | - Claude Messier
- School of Psychology, University of Ottawa Ottawa, ON, Canada
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120
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Uzunova G, Hollander E, Shepherd J. The role of ionotropic glutamate receptors in childhood neurodevelopmental disorders: autism spectrum disorders and fragile x syndrome. Curr Neuropharmacol 2014; 12:71-98. [PMID: 24533017 PMCID: PMC3915351 DOI: 10.2174/1570159x113116660046] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 08/20/2013] [Accepted: 09/25/2013] [Indexed: 12/20/2022] Open
Abstract
Autism spectrum disorder (ASD) and Fragile X syndrome (FXS) are relatively common childhood neurodevelopmental disorders with increasing incidence in recent years. They are currently accepted as disorders of the synapse with alterations in different forms of synaptic communication and neuronal network connectivity. The major excitatory neurotransmitter system in brain, the glutamatergic system, is implicated in learning and memory, synaptic plasticity, neuronal development. While much attention is attributed to the role of metabotropic glutamate receptors in ASD and FXS, studies indicate that the ionotropic glutamate receptors (iGluRs) and their regulatory proteins are also altered in several brain regions. Role of iGluRs in the neurobiology of ASD and FXS is supported by a weight of evidence that ranges from human genetics to in vitro cultured neurons. In this review we will discuss clinical, molecular, cellular and functional changes in NMDA, AMPA and kainate receptors and the synaptic proteins that regulate them in the context of ASD and FXS. We will also discuss the significance for the development of translational biomarkers and treatments for the core symptoms of ASD and FXS.
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Affiliation(s)
- Genoveva Uzunova
- Autism and Obsessive Compulsive Spectrum Program, Department of Psychiatry, Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th St, Bronx, New York 10467-2490
| | - Eric Hollander
- Autism and Obsessive Compulsive Spectrum Program, Department of Psychiatry, Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th St, Bronx, New York 10467-2490
| | - Jason Shepherd
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, 531A Wintrobe, 20N 1900 E, Salt Lake City, Utah 84132
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121
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122
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Carbonetto S. A blueprint for research on Shankopathies: a view from research on autism spectrum disorder. Dev Neurobiol 2013; 74:85-112. [PMID: 24218108 DOI: 10.1002/dneu.22150] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 11/06/2013] [Indexed: 01/21/2023]
Abstract
Autism spectrum disorders (ASD) are associated with mutations in a host of genes including a number that function in synaptic transmission. Phelan McDermid syndrome involves mutations in SHANK3 which encodes a protein that forms a scaffold for glutamate receptors at the synapse. SHANK3 is one of the genes that underpins the synaptic hypothesis for ASD. We discuss this hypothesis with a view to the broader context of ASD and with special emphasis on highly penetrant genetic disorders including Shankopathies. We propose a blueprint for near and longer-term goals for fundamental and translational research on Shankopathies.
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Affiliation(s)
- Salvatore Carbonetto
- Centre for Research in Neuroscience, Department of Neurology, McGill University Health Centre, Montreal, Quebec, H3G1A4, Canada
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123
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Nooh MM, Chumpia MM, Hamilton TB, Bahouth SW. Sorting of β1-adrenergic receptors is mediated by pathways that are either dependent on or independent of type I PDZ, protein kinase A (PKA), and SAP97. J Biol Chem 2013; 289:2277-94. [PMID: 24324269 DOI: 10.1074/jbc.m113.513481] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The β1-adrenergic receptor (β1-AR) is a target for treatment of major cardiovascular diseases, such as heart failure and hypertension. Recycling of agonist-internalized β1-AR is dependent on type I PSD-95/DLG/ZO1 (PDZ) in the C-tail of the β1-AR and on protein kinase A (PKA) activity (Gardner, L. A., Naren, A. P., and Bahouth, S. W. (2007) J. Biol. Chem. 282, 5085-5099). We explored the effects of point mutations in the PDZ and in the activity of PKA on recycling of the β1-AR and its binding to the PDZ-binding protein SAP97. These studies indicated that β1-AR recycling was inhibited by PKA inhibitors and by mutations in the PDZ that interfered with SAP97 binding. The trafficking effects of short sequences differing in PDZ and SAP97 binding were examined using chimeric mutant β1-AR. β1-AR chimera containing the type I PDZ of the β2-adrenergic receptor that does not bind to SAP97 failed to recycle except when serine 312 was mutated to aspartic acid. β1-AR chimera with type I PDZ sequences from the C-tails of aquaporin-2 or GluR1 recycled in a SAP97- and PKA-dependent manner. Non-PDZ β1-AR chimera derived from μ-opioid, dopamine 1, or GluR2 receptors promoted rapid recycling of chimeric β1-AR in a SAP97- and PKA-independent manner. Moreover, the nature of the residue at position -3 in the PDZ regulated whether the β1-AR was internalized alone or in complex with SAP97. These results indicate that divergent pathways were involved in trafficking the β1-AR and provide a roadmap for its trafficking via type I PDZs versus non-PDZs.
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Affiliation(s)
- Mohammed M Nooh
- From the Department of Pharmacology, University of Tennessee Health Sciences Center, Memphis, Tennessee 38163 and
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124
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Lee H, Lee EJ, Song YS, Kim E. Long-term depression-inducing stimuli promote cleavage of the synaptic adhesion molecule NGL-3 through NMDA receptors, matrix metalloproteinases and presenilin/γ-secretase. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130158. [PMID: 24298159 PMCID: PMC3843889 DOI: 10.1098/rstb.2013.0158] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Long-term depression (LTD) reduces the functional strength of excitatory synapses through mechanisms that include the removal of AMPA glutamate receptors from the postsynaptic membrane. LTD induction is also known to result in structural changes at excitatory synapses, including the shrinkage of dendritic spines. Synaptic adhesion molecules are thought to contribute to the development, function and plasticity of neuronal synapses largely through their trans-synaptic adhesions. However, little is known about how synaptic adhesion molecules are altered during LTD. We report here that NGL-3 (netrin-G ligand-3), a postsynaptic adhesion molecule that trans-synaptically interacts with the LAR family of receptor tyrosine phosphatases and intracellularly with the postsynaptic scaffolding protein PSD-95, undergoes a proteolytic cleavage process. NGL-3 cleavage is induced by NMDA treatment in cultured neurons and low-frequency stimulation in brain slices and requires the activities of NMDA glutamate receptors, matrix metalloproteinases (MMPs) and presenilin/γ-secretase. These results suggest that NGL-3 is a novel substrate of MMPs and γ-secretase and that NGL-3 cleavage may regulate synaptic adhesion during LTD.
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Affiliation(s)
- Hyejin Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), , Daejeon 305-701, Korea
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125
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Ramiro-Cortés Y, Hobbiss AF, Israely I. Synaptic competition in structural plasticity and cognitive function. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130157. [PMID: 24298158 DOI: 10.1098/rstb.2013.0157] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Connections between neurons can undergo long-lasting changes in synaptic strength correlating with changes in structure. These events require the synthesis of new proteins, the availability of which can lead to cooperative and competitive interactions between synapses for the expression of plasticity. These processes can occur over limited spatial distances and temporal periods, defining dendritic regions over which activity may be integrated and could lead to the physical rewiring of synapses into functional groups. Such clustering of inputs may increase the computational power of neurons by allowing information to be combined in a greater than additive manner. The availability of new proteins may be a key modulatory step towards activity-dependent, long-term growth or elimination of spines necessary for remodelling of connections. Thus, the aberrant growth or shrinkage of dendritic spines could occur if protein levels are misregulated. Indeed, such perturbations can be seen in several mental retardation disorders, wherein either too much or too little protein translation exists, matching an observed increase or decrease in spine density, respectively. Cellular events which alter protein availability could relieve a constraint on synaptic competition and disturb synaptic clustering mechanisms. These changes may be detrimental to modifications in neural circuitry following activity.
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Affiliation(s)
- Yazmín Ramiro-Cortés
- Champalimaud Neuroscience Programme at Instituto Gulbenkian de Ciência, , 2780-156 Oeiras, Portugal
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126
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Yang Y, Calakos N. Presynaptic long-term plasticity. Front Synaptic Neurosci 2013; 5:8. [PMID: 24146648 PMCID: PMC3797957 DOI: 10.3389/fnsyn.2013.00008] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 09/09/2013] [Indexed: 01/01/2023] Open
Abstract
Long-term synaptic plasticity is a major cellular substrate for learning, memory, and behavioral adaptation. Although early examples of long-term synaptic plasticity described a mechanism by which postsynaptic signal transduction was potentiated, it is now apparent that there is a vast array of mechanisms for long-term synaptic plasticity that involve modifications to either or both the presynaptic terminal and postsynaptic site. In this article, we discuss current and evolving approaches to identify presynaptic mechanisms as well as discuss their limitations. We next provide examples of the diverse circuits in which presynaptic forms of long-term synaptic plasticity have been described and discuss the potential contribution this form of plasticity might add to circuit function. Finally, we examine the present evidence for the molecular pathways and cellular events underlying presynaptic long-term synaptic plasticity.
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Affiliation(s)
- Ying Yang
- Department of Pediatrics, Stanford University School of Medicine Stanford, CA, USA
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Li X, Nooh MM, Bahouth SW. Role of AKAP79/150 protein in β1-adrenergic receptor trafficking and signaling in mammalian cells. J Biol Chem 2013; 288:33797-33812. [PMID: 24121510 DOI: 10.1074/jbc.m113.470559] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein kinase A-anchoring proteins (AKAPs) participate in the formation of macromolecular signaling complexes that include protein kinases, ion channels, effector enzymes, and G-protein-coupled receptors. We examined the role of AKAP79/150 (AKAP5) in trafficking and signaling of the β1-adrenergic receptor (β1-AR). shRNA-mediated down-regulation of AKAP5 in HEK-293 cells inhibited the recycling of the β1-AR. Recycling of the β1-AR in AKAP5 knockdown cells was rescued by shRNA-resistant AKAP5. However, truncated mutants of AKAP5 with deletions in the domains involved in membrane targeting or in binding to calcineurin or PKA failed to restore the recycling of the β1-AR, indicating that full-length AKAP5 was required. Furthermore, recycling of the β1-AR in rat neonatal cardiac myocytes was dependent on targeting the AKAP5-PKA complex to the C-terminal tail of the β1-AR. To analyze the role of AKAP5 more directly, recycling of the β1-AR was determined in ventricular myocytes from AKAP5(-/-) mice. In AKAP5(-/-) myocytes, the agonist-internalized β1-AR did not recycle, except when full-length AKAP5 was reintroduced. These data indicate that AKAP5 exerted specific and profound effects on β1-AR recycling in mammalian cells. Biochemical or real time FRET-based imaging of cyclic AMP revealed that deletion of AKAP5 sensitized the cardiac β1-AR signaling pathway to isoproterenol. Moreover, isoproterenol-mediated increase in contraction rate, surface area, or expression of β-myosin heavy chains was significantly greater in AKAP5(-/-) myocytes than in AKAP5(+/+) myocytes. These results indicate a significant role for the AKAP5 scaffold in signaling and trafficking of the β1-AR in cardiac myocytes and mammalian cells.
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Affiliation(s)
- Xin Li
- Department of Pharmacology, University of Tennessee Health Sciences Center, Memphis, Tennessee 38163
| | - Mohammed M Nooh
- Department of Pharmacology, University of Tennessee Health Sciences Center, Memphis, Tennessee 38163
| | - Suleiman W Bahouth
- Department of Pharmacology, University of Tennessee Health Sciences Center, Memphis, Tennessee 38163.
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128
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Henley JM, Wilkinson KA. AMPA receptor trafficking and the mechanisms underlying synaptic plasticity and cognitive aging. DIALOGUES IN CLINICAL NEUROSCIENCE 2013. [PMID: 23576886 PMCID: PMC3622464 DOI: 10.31887/dcns.2013.15.1/jhenley] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Even in healthy individuals there is an inexorable agerelated decline in cognitive function. This is due, in large part, to reduced synaptic plasticity caused by changes in the molecular composition of the postsynaptic membrane. AMPA receptors (AMPARs) are glutamate-gated cation channels that mediate the overwhelming majority of fast excitatory transmission in the brain. Changes in AMPAR number and/or function are a core feature of synaptic plasticity and age-related cognitive decline, AMPARs are highly dynamic proteins that are subject to highly controlled trafficking, recycling, and/or degradation and replacement. This active regulation of AMPAR synthesis, targeting, synaptic dwell time, and degradation is fundamentally important for memory formation and storage. Further, aberrant AMPAR trafficking and consequent detrimental changes in synapses are strongly implicated in many brain diseases, which represent a vast social and economic burden. The purpose of this article is to provide an overview of the molecular and cellular AMPA receptor trafficking events that control synaptic responsiveness and plasticity, and highlight what is known currently known about how these processes change with age and disease.
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Affiliation(s)
- Jeremy M Henley
- School of Biochemistry, MRC Centre for Synaptic Plasticity, University of Bristol, Bristol, UK.
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129
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Kumari R, Castillo C, Francesconi A. Agonist-dependent signaling by group I metabotropic glutamate receptors is regulated by association with lipid domains. J Biol Chem 2013; 288:32004-19. [PMID: 24045944 DOI: 10.1074/jbc.m113.475863] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Group I metabotropic glutamate receptors (mGluRs), mGluR1 and mGluR5, play critical functions in forms of activity-dependent synaptic plasticity and synapse remodeling in physiological and pathological states. Importantly, in animal models of fragile X syndrome, group I mGluR activity is abnormally enhanced, a dysfunction that may partly underlie cognitive deficits in the condition. Lipid rafts are cholesterol- and sphingolipid-enriched membrane domains that are thought to form transient signaling platforms for ligand-activated receptors. Many G protein-coupled receptors, including group I mGluRs, are present in lipid rafts, but the mechanisms underlying recruitment to these membrane domains remain incompletely understood. Here, we show that mGluR1 recruitment to lipid rafts is enhanced by agonist binding and is supported at least in part by an intact cholesterol recognition/interaction amino acid consensus (CRAC) motif in the receptor. Substitutions of critical residues in the motif reduce mGluR1 association with lipid rafts and agonist-induced, mGluR1-dependent activation of extracellular-signal-activated kinase1/2 MAP kinase (ERK-MAPK). We find that alteration of membrane cholesterol content or perturbation of lipid rafts regulates agonist-dependent activation of ERK-MAPK by group I mGluRs, suggesting a potential function for cholesterol as a positive allosteric modulator of receptor function(s). Together, these findings suggest that drugs that alter membrane cholesterol levels or directed to the receptor-cholesterol interface could be employed to modulate abnormal group I mGluR activity in neuropsychiatric conditions, including fragile X syndrome.
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Affiliation(s)
- Ranju Kumari
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
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130
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Han L, Campanucci VA, Cooke J, Salter MW. Identification of a single amino acid in GluN1 that is critical for glycine-primed internalization of NMDA receptors. Mol Brain 2013; 6:36. [PMID: 23941530 PMCID: PMC3846451 DOI: 10.1186/1756-6606-6-36] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 08/12/2013] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND NMDA receptors are ligand-gated ion channels with essential roles in glutamatergic synaptic transmission and plasticity in the CNS. As co-receptors for glutamate and glycine, gating of the NMDA receptor/channel pore requires agonist binding to the glycine sites, as well as to the glutamate sites, on the ligand-binding domains of the receptor. In addition to channel gating, glycine has been found to prime NMDA receptors for internalization upon subsequent stimulation of glutamate and glycine sites. RESULTS Here we address the key issue of identifying molecular determinants in the glycine-binding subunit, GluN1, that are essential for priming of NMDA receptors. We found that glycine treatment of wild-type NMDA receptors led to recruitment of the adaptor protein 2 (AP-2), and subsequent internalization after activating the receptors by NMDA plus glycine. However, with a glycine-binding mutant of GluN1 - N710R/Y711R/E712A/A714L - we found that treating with glycine did not promote recruitment of AP-2 nor were glycine-treated receptors internalized when subsequently activated with NMDA plus glycine. Likewise, GluN1 carrying a single point mutation - A714L - did not prime upon glycine treatment. Importantly, both of the mutant receptors were functional, as stimulating with NMDA plus glycine evoked inward currents. CONCLUSIONS Thus, we have identified a single amino acid in GluN1 that is critical for priming of NMDA receptors by glycine. Moreover, we have demonstrated the principle that while NMDA receptor gating and priming share a common requirement for glycine binding, the molecular constraints in GluN1 for gating are distinct from those for priming.
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Affiliation(s)
- Lu Han
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave, Toronto, Ontario M5G 1X8, Canada.
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131
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Modulation of mGluR-dependent MAP1B translation and AMPA receptor endocytosis by microRNA miR-146a-5p. J Neurosci 2013; 33:9013-20. [PMID: 23699512 DOI: 10.1523/jneurosci.5210-12.2013] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The translation of dendritic microtubule-associated protein 1B (MAP1B) is exaggerated upon group I mGluR activation leading to AMPA receptor (AMPAR) endocytosis and consequent long-term depression. However, the mechanisms of regulation of MAP1B protein synthesis in the mature dendrites remain unclear. Here we have identified miR-146a-5p that targets the 3' UTR of MAP1B mRNA and represses its translation. Inhibition of the endogenous miR-146a-5p in mouse cultured hippocampal neurons triggers an increase of the dendritic MAP1B protein as well as the internalization of AMPARs, resulting in a decline in synaptic transmission. Conversely, enforced expression of miR-146a-5p inhibits MAP1B translation and attenuates group I mGluR-induced AMPAR endocytosis. Moreover, siRNA-mediated knockdown of MAP1B recovers the impairment of synaptic transmission caused by inhibition of miR-146a-5p. These results reveal that miR-146a-5p modulates the synaptic plasticity via repression of MAP1B protein synthesis.
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132
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Long lasting protein synthesis- and activity-dependent spine shrinkage and elimination after synaptic depression. PLoS One 2013; 8:e71155. [PMID: 23951097 PMCID: PMC3739806 DOI: 10.1371/journal.pone.0071155] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 07/02/2013] [Indexed: 11/30/2022] Open
Abstract
Neuronal circuits modify their response to synaptic inputs in an experience-dependent fashion. Increases in synaptic weights are accompanied by structural modifications, and activity dependent, long lasting growth of dendritic spines requires new protein synthesis. When multiple spines are potentiated within a dendritic domain, they show dynamic structural plasticity changes, indicating that spines can undergo bidirectional physical modifications. However, it is unclear whether protein synthesis dependent synaptic depression leads to long lasting structural changes. Here, we investigate the structural correlates of protein synthesis dependent long-term depression (LTD) mediated by metabotropic glutamate receptors (mGluRs) through two-photon imaging of dendritic spines on hippocampal pyramidal neurons. We find that induction of mGluR-LTD leads to robust and long lasting spine shrinkage and elimination that lasts for up to 24 hours. These effects depend on signaling through group I mGluRs, require protein synthesis, and activity. These data reveal a mechanism for long lasting remodeling of synaptic inputs, and offer potential insights into mental retardation.
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Cook D, Nuro E, Murai KK. Increasing our understanding of human cognition through the study of Fragile X Syndrome. Dev Neurobiol 2013; 74:147-77. [PMID: 23723176 PMCID: PMC4216185 DOI: 10.1002/dneu.22096] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 05/17/2013] [Indexed: 12/16/2022]
Abstract
Fragile X Syndrome (FXS) is considered the most common form of inherited intellectual disability. It is caused by reductions in the expression level or function of a single protein, the Fragile X Mental Retardation Protein (FMRP), a translational regulator which binds to approximately 4% of brain messenger RNAs. Accumulating evidence suggests that FXS is a complex disorder of cognition, involving interactions between genetic and environmental influences, leading to difficulties in acquiring key life skills including motor skills, language, and proper social behaviors. Since many FXS patients also present with one or more features of autism spectrum disorders (ASDs), insights gained from studying the monogenic basis of FXS could pave the way to a greater understanding of underlying features of multigenic ASDs. Here we present an overview of the FXS and FMRP field with the goal of demonstrating how loss of a single protein involved in translational control affects multiple stages of brain development and leads to debilitating consequences on human cognition. We also focus on studies which have rescued or improved FXS symptoms in mice using genetic or therapeutic approaches to reduce protein expression. We end with a brief description of how deficits in translational control are implicated in FXS and certain cases of ASDs, with many recent studies demonstrating that ASDs are likely caused by increases or decreases in the levels of certain key synaptic proteins. The study of FXS and its underlying single genetic cause offers an invaluable opportunity to study how a single gene influences brain development and behavior.
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Affiliation(s)
- Denise Cook
- Department of Neurology and Neurosurgery, Centre for Research in Neuroscience, The Research Institute of the McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada
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134
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Kandratavicius L, Rosa-Neto P, Monteiro MR, Guiot MC, Assirati JA, Carlotti CG, Kobayashi E, Leite JP. Distinct increased metabotropic glutamate receptor type 5 (mGluR5) in temporal lobe epilepsy with and without hippocampal sclerosis. Hippocampus 2013; 23:1212-30. [PMID: 23804486 PMCID: PMC4165311 DOI: 10.1002/hipo.22160] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2013] [Indexed: 12/04/2022]
Abstract
Metabotropic glutamate receptor type 5 (mGluR5) upregulation in temporal lobe epilepsy (TLE) and the correlation of its expression with features of hippocampal sclerosis (HS) remains unclear. Here we characterized mGluR5 immunoreactivity in hippocampus, entorhinal cortex (EC), and subiculum of TLE specimens with confirmed HS, with neocortical TLE (non-HS) and necropsy controls. We correlated mGluR5 immunoreactivity with neuronal density, mossy fiber sprouting, astrogliosis (GFAP), and dendritic alterations (MAP2). TLE specimens showed increased mGluR5 expression, which was most pronounced in the EC, subiculum, CA2, and dentate gyrus outer molecular layer. Increased mGluR5 expression was seen in hippocampal head and body segments and was independent of neuronal density, astrogliosis, or dendritic alterations. Positive correlation between mGluR5 expression with mossy fiber sprouting and with MAP2 in CA3 and CA1 was found only in HS specimens. Negative correlation between mGluR5 expression with seizure frequency and epilepsy duration was found only in non-HS cases. Specimens from HS patients without previous history of febrile seizure (FS) showed higher mGluR5 and MAP2 expression in CA2. Our study suggests that mGluR5 upregulation is part of a repertoire of post-synaptic adaptations that might control overexcitation and excessive glutamate release rather than a dysfunction that leads to seizure facilitation. That would explain why non-HS cases, on which seizures are likely to originate outside the hippocampal formation, also exhibit upregulated mGluR5. On the other hand, lower mGluR5 expression was related to increased seizure frequency. In addition to its role in hyperexcitability, mGluR5 upregulation could play a role in counterbalance mechanisms along the hyperexcitable circuitry uniquely altered in sclerotic hippocampal formation. Inefficient post-synaptic compensatory morphological (dendritic branching) and glutamatergic (mGluR5 expression) mechanisms in CA2 subfield could potentially underlie the association of FS with HS and TLE. © 2013 Wiley Periodicals, Inc.
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Affiliation(s)
- Ludmyla Kandratavicius
- Department of Neurosciences and Behavior, Ribeirao Preto Medical School, University of Sao PauloBrazil
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill UniversityMontreal, Canada
| | - Pedro Rosa-Neto
- Translational Neuroimaging Laboratory, Department of Neurology and Neurosurgery, Douglas Research Institute, McGill UniversityMontreal, Canada
| | - Mariana Raquel Monteiro
- Department of Neurosciences and Behavior, Ribeirao Preto Medical School, University of Sao PauloBrazil
| | - Marie-Christine Guiot
- Department of Pathology, Montreal Neurological Institute, McGill UniversityMontreal, Canada
| | | | | | - Eliane Kobayashi
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill UniversityMontreal, Canada
| | - Joao Pereira Leite
- Department of Neurosciences and Behavior, Ribeirao Preto Medical School, University of Sao PauloBrazil
- *Correspondence to: Joao Pereira Leite, Ribeirao Preto Medical School, Department of Neurosciences and Behavior, University of Sao Paulo, Av Bandeirantes 3900, 14049-900, Ribeirao Preto, SP, Brazil. E-mail:
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135
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Sourial M, Cheng C, Doering LC. Progress toward therapeutic potential for AFQ056 in Fragile X syndrome. J Exp Pharmacol 2013; 5:45-54. [PMID: 27186135 PMCID: PMC4863540 DOI: 10.2147/jep.s27044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Fragile X syndrome (FXS) is the most common form of inherited intellectual disability and the leading single-gene cause of autism. It is caused by the lack of production of the Fragile X mental retardation protein (FMRP), resulting in cognitive deficits, hyperactivity, and autistic behaviors. Breakthrough advances in potential therapy for FXS followed the discovery that aberrant group 1 metabotropic glutamate receptor (mGluR) signaling is an important constituent of the pathophysiology of the syndrome. Research has indicated that upon neuronal stimulation, FMRP acts downstream of group 1 mGluRs (mGluRs1/5) to inhibit protein synthesis, long-term depression, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor internalization. To offset the deficits caused by the lack of FMRP, many pharmaceutical companies have designed medicinal drugs to target the unrestrained stimulation of mGluR5 signaling in FXS. Indeed, promising results from animal and clinical studies suggest that mGluR5 antagonists such as AFQ056 can successfully correct many of the deficits in FXS. In this review, we cover the animal studies performed to date that test the role of AFQ056 as a selective mGluR5 antagonist to alleviate the phenotypes of FXS.
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Affiliation(s)
- Mary Sourial
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Connie Cheng
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Laurie C Doering
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
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136
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Herrold AA, Persons AL, Napier TC. Cellular distribution of AMPA receptor subunits and mGlu5 following acute and repeated administration of morphine or methamphetamine. J Neurochem 2013; 126:503-17. [PMID: 23711322 DOI: 10.1111/jnc.12323] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Revised: 05/09/2013] [Accepted: 05/14/2013] [Indexed: 01/14/2023]
Abstract
Ionotropic AMPA receptors (AMPAR) and metabotropic glutamate group I subtype 5 receptors (mGlu5) mediate neuronal and behavioral effects of abused drugs. mGlu5 stimulation increases expression of striatal-enriched tyrosine phosphatase isoform 61 (STEP61 ) which internalizes AMPARs. We determined the rat brain profile of these proteins using two different classes of abused drugs, opiates, and stimulants. STEP61 levels, and cellular distribution/expression of AMPAR subunits (GluA1, GluA2) and mGlu5, were evaluated via a protein cross-linking assay in medial prefrontal cortex (mPFC), nucleus accumbens (NAc), and ventral pallidum (VP) harvested 1 day after acute, or fourteen days after repeated morphine (8 mg/kg) or methamphetamine (1 mg/kg) (treatments producing behavioral sensitization). Acute morphine decreased GluA1 and GluA2 surface expression in mPFC and GluA1 in NAc. Fourteen days after repeated morphine or methamphetamine, mGlu5 surface expression increased in VP. In mPFC, mGlu5 were unaltered; however, after methamphetamine, STEP61 levels decreased and GluA2 surface expression increased. Pre-treatment with a mGlu5-selective negative allosteric modulator, blocked methamphetamine-induced behavioral sensitization and changes in mPFC GluA2 and STEP61 . These data reveal (i) region-specific distinctions in glutamate receptor trafficking between acute and repeated treatments of morphine and methamphetamine, and (ii) that mGlu5 is necessary for methamphetamine-induced alterations in mPFC GluA2 and STEP61 .
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Affiliation(s)
- Amy A Herrold
- Laboratory of Origin, Department of Pharmacology, Center for Compulsive Behavior and Addiction, Rush University Medical Center, Chicago, Illinois 60612, USA
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137
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Simultaneous monitoring of presynaptic transmitter release and postsynaptic receptor trafficking reveals an enhancement of presynaptic activity in metabotropic glutamate receptor-mediated long-term depression. J Neurosci 2013; 33:5867-5877. [PMID: 23536098 DOI: 10.1523/jneurosci.1508-12.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Although the contribution of postsynaptic mechanisms to long-term synaptic plasticity has been studied extensively, understanding the contribution of presynaptic modifications to this process lags behind, primarily because of a lack of techniques with which to directly and quantifiably measure neurotransmitter release from synaptic terminals. Here, we developed a method to measure presynaptic activity through the biotinylation of vesicular transporters in vesicles fused with presynaptic membranes during neurotransmitter release. This method allowed us for the first time to selectively quantify the spontaneous or evoked release of glutamate or GABA at their respective synapses. Using this method to investigate presynaptic changes during the expression of group I metabotropic glutamate receptor (mGluR1/5)-mediated long-term depression (LTD) in cultured rat hippocampal neurons, we discovered that this form of LTD was associated with increased presynaptic release of glutamate, despite reduced miniature EPSCs measured with whole-cell recording. Moreover, we found that specific blockade of AMPA receptor (AMPAR) endocytosis with a membrane-permeable GluR2-derived peptide not only prevented the expression of LTD but also eliminated LTD-associated increase in presynaptic release. Thus, our work not only demonstrates that mGluR1/5-mediated LTD is associated with increased endocytosis of postsynaptic AMPARs but also reveals an unexpected homeostatic/compensatory increase in presynaptic release. In addition, this study indicates that biotinylation of vesicular transporters in live cultured neurons is a valuable tool for studying presynaptic function.
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138
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SAP97 controls the trafficking and resensitization of the beta-1-adrenergic receptor through its PDZ2 and I3 domains. PLoS One 2013; 8:e63379. [PMID: 23696820 PMCID: PMC3656048 DOI: 10.1371/journal.pone.0063379] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Accepted: 04/03/2013] [Indexed: 01/11/2023] Open
Abstract
Previous studies have determined that the type-1 PDZ sequence at the extreme carboxy-terminus of the ß1-adrenergic receptor (ß1-AR) binds SAP97 and AKAP79 to organize a scaffold involved in trafficking of the ß1-AR. In this study we focused on characterizing the domains in SAP97 that were involved in recycling and resensitization of the ß1-AR in HEK-293 cells. Using a SAP97 knockdown and rescue strategy, we determined that PDZ-deletion mutants of SAP97 containing PDZ2 rescued the recycling and resensitization of the ß1-AR. Among the three PDZs of SAP97, PDZ2 displayed the highest affinity in binding to the ß1-AR. Expression of isolated PDZ2, but not the other PDZs, inhibited the recycling of the ß1-AR by destabilizing the macromolecular complex involved in trafficking and functional resensitization of the ß1-AR. In addition to its PDZs, SAP97 contains other protein interacting domains, such as the I3 sequence in the SRC homology-3 (SH3) domain, which binds to AKAP79. Deletion of I3 from SAP97 (ΔI3-SAP97) did not affect the binding of SAP97 to the ß1-AR. However, ΔI3-SAP97 could not rescue the recycling of the ß1-AR because it failed to incorporate AKAP79/PKA into the SAP97-ß1-AR complex. Therefore, bipartite binding of SAP97 to the ß1-AR and to AKAP79 is necessary for SAP97-mediated effects on recycling, externalization and functional resensitization of the ß1-AR. These data establish a prominent role for PDZ2 and I3 domains of SAP97 in organizing the ß1-adrenergic receptosome involved in connecting the ß1-AR to trafficking and signaling networks.
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139
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Bai N, Hayashi H, Aida T, Namekata K, Harada T, Mishina M, Tanaka K. Dock3 interaction with a glutamate-receptor NR2D subunit protects neurons from excitotoxicity. Mol Brain 2013; 6:22. [PMID: 23641686 PMCID: PMC3652797 DOI: 10.1186/1756-6606-6-22] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 03/28/2013] [Indexed: 11/25/2022] Open
Abstract
Background N-methyl-D-aspartate receptors (NMDARs) are critical for neuronal development and synaptic plasticity. Dysregulation of NMDARs is implicated in neuropsychiatric disorders. Native NMDARs are heteromultimeric protein complexes consisting of NR1 and NR2 subunits. NR2 subunits (NR2A–D) are the major determinants of the functional properties of NMDARs. Most research has focused on NR2A- and/or NR2B-containing receptors. A recent study demonstrated that NR2C- and/or NR2D-containing NMDARs are the primary targets of memantine, a drug that is widely prescribed to treat Alzheimer’s disease. Our laboratory demonstrated that memantine prevents the loss of retinal ganglion cells (RGCs) in GLAST glutamate transporter knockout mice, a model of normal tension glaucoma (NTG), suggesting that NR2D-containing receptors may be involved in RGC loss in NTG. Results Here we demonstrate that NR2D deficiency attenuates RGC loss in GLAST-deficient mice. Furthermore, Dock3, a guanine nucleotide exchange factor, binds to the NR2D C-terminal domain and reduces the surface expression of NR2D, thereby protecting RGCs from excitotoxicity. Conclusions These results suggest that NR2D is involved in the degeneration of RGCs induced by excitotoxicity, and that the interaction between NR2D and Dock3 may have a neuroprotective effect. These findings raise the possibility that NR2D and Dock3 might be potential therapeutic targets for treating neurodegenerative diseases such as Alzheimer’s disease and NTG.
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Affiliation(s)
- Ning Bai
- Laboratory of Molecular Neuroscience, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
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140
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Tyrosine phosphorylation regulates the endocytosis and surface expression of GluN3A-containing NMDA receptors. J Neurosci 2013; 33:4151-64. [PMID: 23447623 DOI: 10.1523/jneurosci.2721-12.2013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Selective control of receptor trafficking provides a mechanism for remodeling the receptor composition of excitatory synapses, and thus supports synaptic transmission, plasticity, and development. GluN3A (formerly NR3A) is a nonconventional member of the NMDA receptor (NMDAR) subunit family, which endows NMDAR channels with low calcium permeability and reduced magnesium sensitivity compared with NMDARs comprising only GluN1 and GluN2 subunits. Because of these special properties, GluN3A subunits act as a molecular brake to limit the plasticity and maturation of excitatory synapses, pointing toward GluN3A removal as a critical step in the development of neuronal circuitry. However, the molecular signals mediating GluN3A endocytic removal remain unclear. Here we define a novel endocytic motif (YWL), which is located within the cytoplasmic C-terminal tail of GluN3A and mediates its binding to the clathrin adaptor AP2. Alanine mutations within the GluN3A endocytic motif inhibited clathrin-dependent internalization and led to accumulation of GluN3A-containing NMDARs at the cell surface, whereas mimicking phosphorylation of the tyrosine residue promoted internalization and reduced cell-surface expression as shown by immunocytochemical and electrophysiological approaches in recombinant systems and rat neurons in primary culture. We further demonstrate that the tyrosine residue is phosphorylated by Src family kinases, and that Src-activation limits surface GluN3A expression in neurons. Together, our results identify a new molecular signal for GluN3A internalization that couples the functional surface expression of GluN3A-containing receptors to the phosphorylation state of GluN3A subunits, and provides a molecular framework for the regulation of NMDAR subunit composition with implications for synaptic plasticity and neurodevelopment.
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141
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Sidorov MS, Auerbach BD, Bear MF. Fragile X mental retardation protein and synaptic plasticity. Mol Brain 2013; 6:15. [PMID: 23566911 PMCID: PMC3636002 DOI: 10.1186/1756-6606-6-15] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 03/25/2013] [Indexed: 12/20/2022] Open
Abstract
Loss of the translational repressor FMRP causes Fragile X syndrome. In healthy neurons, FMRP modulates the local translation of numerous synaptic proteins. Synthesis of these proteins is required for the maintenance and regulation of long-lasting changes in synaptic strength. In this role as a translational inhibitor, FMRP exerts profound effects on synaptic plasticity.
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Affiliation(s)
- Michael S Sidorov
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 46-3301, USA
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142
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Mao SC, Chang CH, Wu CC, Orejanera MJ, Manzoni OJ, Gean PW. Inhibition of spontaneous recovery of fear by mGluR5 after prolonged extinction training. PLoS One 2013; 8:e59580. [PMID: 23555716 PMCID: PMC3605338 DOI: 10.1371/journal.pone.0059580] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 02/15/2013] [Indexed: 11/19/2022] Open
Abstract
Fear behavior is vital for survival and involves learning contingent associations of non-threatening cues with aversive stimuli. In contrast, excessive levels of fear can be maladaptive and lead to anxiety disorders. Generally, extensive sessions of extinction training correlates with reduced spontaneous recovery. The molecular mechanisms underlying the long-term inhibition of fear recovery following repeated extinction training are not fully understood. Here we show that in rats, prolonged extinction training causes greater reduction in both fear-potentiated startle and spontaneous recovery. This effect was specifically blocked by metabotropic glutamate receptor 5 (mGluR5), but not by mGluR1 antagonists and by a protein synthesis inhibitor. Similar inhibition of memory recovery following prolonged extinction training was also observed in mice. In agreement with the instrumental role of mGluR5 in the prolonged inhibition of fear recovery, we found that FMR1-/- mice which exhibit enhanced mGluR5-mediated signaling exhibit lower spontaneous recovery of fear after extinction training than wild-type littermates. At the molecular level, we discovered that prolonged extinction training reversed the fear conditioning-induced increase in surface expression of GluR1, AMPA/NMDA ratio, postsynaptic density-95 (PSD-95) and synapse-associated protein-97 (SAP97). Accordingly, delivery of Tat-GluR2(3Y), a synthetic peptide that blocks AMPA receptor endocytosis, inhibited prolonged extinction training-induced inhibition of fear recovery. Together, our results demonstrate that prolonged extinction training results in the mGluR5-dependent long-term inhibition of fear recovery. This effect may involve the degradation of original memory and may explain the beneficial effects of prolonged exposure therapy for the treatment of phobias.
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Affiliation(s)
- Sheng-Chun Mao
- Institute of Basic Medical Sciences and Department of Pharmacology, National Cheng-Kung University, Tainan, Taiwan
| | - Chih-Hua Chang
- Institute of Basic Medical Sciences and Department of Pharmacology, National Cheng-Kung University, Tainan, Taiwan
| | - Chia-Chen Wu
- Institute of Basic Medical Sciences and Department of Pharmacology, National Cheng-Kung University, Tainan, Taiwan
| | | | | | - Po-Wu Gean
- Institute of Basic Medical Sciences and Department of Pharmacology, National Cheng-Kung University, Tainan, Taiwan
- * E-mail: (P-WG); (OJM)
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143
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Mukherjee S, Manahan-Vaughan D. Role of metabotropic glutamate receptors in persistent forms of hippocampal plasticity and learning. Neuropharmacology 2013; 66:65-81. [DOI: 10.1016/j.neuropharm.2012.06.005] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 05/31/2012] [Accepted: 06/01/2012] [Indexed: 12/27/2022]
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144
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Linking the fragile X mental retardation protein to the lipoxygenase pathway. Med Hypotheses 2013; 80:289-91. [DOI: 10.1016/j.mehy.2012.11.046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 11/09/2012] [Accepted: 11/25/2012] [Indexed: 02/08/2023]
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145
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Tambuyzer T, Ahmed T, Taylor CJ, Berckmans D, Balschun D, Aerts JM. System Identification of mGluR-Dependent Long-Term Depression. Neural Comput 2013; 25:650-70. [DOI: 10.1162/neco_a_00408] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Recent advances have started to uncover the underlying mechanisms of metabotropic glutamate receptor (mGluR)–dependent long-term depression (LTD). However, it is not completely clear how these mechanisms are linked, and it is believed that several crucial mechanisms remain to be revealed. In this study, we investigated whether system identification (SI) methods can be used to gain insight into the mechanisms of synaptic plasticity. SI methods have been shown to be an objective and powerful approach for describing how sensory neurons encode information about stimuli. However, to our knowledge, it is the first time that SI methods have been applied to electrophysiological brain slice recordings of synaptic plasticity responses. The results indicate that the SI approach is a valuable tool for reverse-engineering of mGluR-LTD responses. We suggest that such SI methods can aid in unraveling the complexities of synaptic function.
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Affiliation(s)
- Tim Tambuyzer
- M3-BIORES: Measure, Model and Manage Bioresponses, Department of Biosystems, Catholic University of Leuven, Leuven B-3001, Belgium
| | - Tariq Ahmed
- Laboratory for Biological Psychology, Department of Psychology, Catholic University of Leuven, Leuven B-3001, Belgium
| | - C. James Taylor
- Engineering Department, Lancaster University, Lancaster, LA1 4YR, U.K
| | - Daniel Berckmans
- M3-BIORES: Measure, Model and Manage Bioresponses, Department of Biosystems, Catholic University of Leuven, Leuven B-3001, Belgium
| | - Detlef Balschun
- Laboratory for Biological Psychology, Department of Psychology, Catholic University of Leuven, Leuven B-3001, Belgium
| | - Jean-Marie Aerts
- M3-BIORES: Measure, Model and Manage Bioresponses, Department of Biosystems, Catholic University of Leuven, Leuven, Belgium
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146
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Asrar S, Jia Z. Molecular mechanisms coordinating functional and morphological plasticity at the synapse: Role of GluA2/N-cadherin interaction-mediated actin signaling in mGluR-dependent LTD. Cell Signal 2013; 25:397-402. [DOI: 10.1016/j.cellsig.2012.11.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 11/05/2012] [Indexed: 11/25/2022]
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147
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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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148
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Politte LC, McDougle CJ. Phase II and III drugs for the treatment of fragile X syndrome. Expert Opin Orphan Drugs 2012. [DOI: 10.1517/21678707.2013.750240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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149
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Huang CC, Hsu KS. Activation of NMDA receptors reduces metabotropic glutamate receptor-induced long-term depression in the nucleus accumbens via a CaMKII-dependent mechanism. Neuropharmacology 2012; 63:1298-307. [DOI: 10.1016/j.neuropharm.2012.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 07/30/2012] [Accepted: 08/14/2012] [Indexed: 01/12/2023]
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150
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Novel glycine-dependent inactivation of NMDA receptors in cultured hippocampal neurons. Neurosci Bull 2012; 28:550-60. [PMID: 22968593 DOI: 10.1007/s12264-012-1266-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 05/07/2012] [Indexed: 10/27/2022] Open
Abstract
OBJECTIVE Glycine acts as a co-agonist for the activation of N-methyl-D-aspartate receptors (NMDARs) by binding to glycine sites, thus potentiating glutamate-elicited responses and inhibiting NMDAR desensitization in a dose-dependent manner. The present study aimed to characterize the glycine-dependent inactivation of NMDARs and to explore its pathophysiological significance. METHODS Primary hippocampal cell cultures from embryonic days 17-18 rats were treated with NMDA or NMDA plus glycine. Patch-clamp recording and intracellular Ca(2+) imaging were performed to test the effects of glycine on NMDA-activated currents and increase of intracellular free Ca(2+) respectively. Immunofluorescence staining was conducted to examine NR1 internalization. Cell damage was tested with MTT method and lactate dehydrogenase leakage. RESULTS Glycine reduced the peak current and Ca(2+) influx elicited by NMDA application at concentrations ≥ 300 μmol/L. This is a novel suppressive influence of glycine on NMDAR function, since it occurs via the NMDAR glycine-binding site, in contrast to the classic suppression, which occurs through the binding of glycine to glycine receptors. The level of membrane NMDARs was measured to evaluate whether internalization was involved. Immunohistochemical labeling showed that incubation with high concentrations of NMDA plus glycine did not change the expression of NMDARs on the cell surface when compared to the expression without glycine; hence the possibility of NMDAR internalization primed by glycine binding was excluded. CONCLUSION In summary, the novel suppressive effect of glycine on NMDARs was mediated via binding to the glycine site of the NMDAR and not by activation of the strychnine-sensitive glycine-receptor-gated chloride channel or by the internalization of NMDARs. The inhibitory influence of glycine on NMDARs adds a new insight to our knowledge of the complexity of synaptic transmission.
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