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Chen Y, Liu S, Jacobi AA, Jeng G, Ulrich JD, Stein IS, Patriarchi T, Hell JW. Rapid sequential clustering of NMDARs, CaMKII, and AMPARs upon activation of NMDARs at developing synapses. Front Synaptic Neurosci 2024; 16:1291262. [PMID: 38660466 PMCID: PMC11039796 DOI: 10.3389/fnsyn.2024.1291262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 03/22/2024] [Indexed: 04/26/2024] Open
Abstract
Rapid, synapse-specific neurotransmission requires the precise alignment of presynaptic neurotransmitter release and postsynaptic receptors. How postsynaptic glutamate receptor accumulation is induced during maturation is not well understood. We find that in cultures of dissociated hippocampal neurons at 11 days in vitro (DIV) numerous synaptic contacts already exhibit pronounced accumulations of the pre- and postsynaptic markers synaptotagmin, synaptophysin, synapsin, bassoon, VGluT1, PSD-95, and Shank. The presence of an initial set of AMPARs and NMDARs is indicated by miniature excitatory postsynaptic currents (mEPSCs). However, AMPAR and NMDAR immunostainings reveal rather smooth distributions throughout dendrites and synaptic enrichment is not obvious. We found that brief periods of Ca2+ influx through NMDARs induced a surprisingly rapid accumulation of NMDARs within 1 min, followed by accumulation of CaMKII and then AMPARs within 2-5 min. Postsynaptic clustering of NMDARs and AMPARs was paralleled by an increase in their mEPSC amplitudes. A peptide that blocked the interaction of NMDAR subunits with PSD-95 prevented the NMDAR clustering. NMDAR clustering persisted for 3 days indicating that brief periods of elevated glutamate fosters permanent accumulation of NMDARs at postsynaptic sites in maturing synapses. These data support the model that strong glutamatergic stimulation of immature glutamatergic synapses results in a fast and substantial increase in postsynaptic NMDAR content that required NMDAR binding to PSD-95 or its homologues and is followed by recruitment of CaMKII and subsequently AMPARs.
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Affiliation(s)
- Yucui Chen
- Department of Pharmacology, University of Iowa, Iowa City, IA, United States
| | - Shangming Liu
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Ariel A. Jacobi
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Grace Jeng
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Jason D. Ulrich
- Department of Pharmacology, University of Iowa, Iowa City, IA, United States
| | - Ivar S. Stein
- Department of Pharmacology, University of Iowa, Iowa City, IA, United States
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Tommaso Patriarchi
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Johannes W. Hell
- Department of Pharmacology, University of Iowa, Iowa City, IA, United States
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
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2
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Maternal Hyperhomocysteinemia Produces Memory Deficits Associated with Impairment of Long-Term Synaptic Plasticity in Young Rats. Cells 2022; 12:cells12010058. [PMID: 36611852 PMCID: PMC9818716 DOI: 10.3390/cells12010058] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/20/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022] Open
Abstract
Maternal hyperhomocysteinemia (HCY) is a common pregnancy complication caused by high levels of the homocysteine in maternal and fetal blood, which leads to the alterations of the cognitive functions, including learning and memory. In the present study, we investigated the mechanisms of these alterations in a rat model of maternal HCY. The behavioral tests confirmed the memory impairments in young and adult rats following the prenatal HCY exposure. Field potential recordings in hippocampal slices demonstrated that the long-term potentiation (LTP) was significantly reduced in HCY rats. The whole-cell patch-clamp recordings in hippocampal slices demonstrated that the magnitude of NMDA receptor-mediated currents did not change while their desensitization decreased in HCY rats. No significant alterations of glutamate receptor subunit expression except GluN1 were detected in the hippocampus of HCY rats using the quantitative real-time PCR and Western blot methods. The immunofluorescence microscopy revealed that the number of synaptopodin-positive spines is reduced, while the analysis of the ultrastructure of hippocampus using the electron microscopy revealed the indications of delayed hippocampal maturation in young HCY rats. Thus, the obtained results suggest that maternal HCY disturbs the maturation of hippocampus during the first month of life, which disrupts LTP formation and causes memory impairments.
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3
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Xu L, Zhou Y, Hu L, Jiang H, Dong Y, Shen H, Lou Z, Yang S, Ji Y, Ruan L, Zhang X. Deficits in N-Methyl-D-Aspartate Receptor Function and Synaptic Plasticity in Hippocampal CA1 in APP/PS1 Mouse Model of Alzheimer's Disease. Front Aging Neurosci 2021; 13:772980. [PMID: 34916926 PMCID: PMC8669806 DOI: 10.3389/fnagi.2021.772980] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 10/29/2021] [Indexed: 12/24/2022] Open
Abstract
The N-methyl-D-aspartate receptor is a critical molecule for synaptic plasticity and cognitive function. Impaired synaptic plasticity is thought to contribute to the cognitive impairment associated with Alzheimer’s disease (AD). However, the neuropathophysiological alterations of N-methyl-D-aspartate receptor (NMDAR) function and synaptic plasticity in hippocampal CA1 in transgenic rodent models of AD are still unclear. In the present study, APP/PS1 mice were utilized as a transgenic model of AD, which exhibited progressive cognitive impairment including defective working memory, recognition memory, and spatial memory starting at 6 months of age and more severe by 8 months of age. We found an impaired long-term potentiation (LTP) and reduced NMDAR-mediated spontaneous excitatory postsynaptic currents (sEPSCs) in the hippocampal CA1 of APP/PS1 mice with 8 months of age. Golgi staining revealed that dendrites of pyramidal neurons had shorter length, fewer intersections, and lower spine density in APP/PS1 mice compared to control mice. Further, the reduced expression levels of NMDAR subunits, PSD95 and SNAP25 were observed in the hippocampus of APP/PS1 mice. These results suggest that NMDAR dysfunction, impaired synaptic plasticity, and disrupted neuronal morphology constitute an important part of the neuropathophysiological alterations associated with cognitive impairment in APP/PS1 mice.
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Affiliation(s)
- Le Xu
- Zhejiang Key Laboratory of Pathophysiology, Department of Pharmacology, School of Medicine, Ningbo University, Ningbo, China.,Department of Psychosomatic Medicine, Ningbo First Hospital, Ningbo Hospital of Zhejiang University, Ningbo, China
| | - Yiying Zhou
- Zhejiang Key Laboratory of Pathophysiology, Department of Pharmacology, School of Medicine, Ningbo University, Ningbo, China.,Key Laboratory of Addiction Research of Zhejiang Province, Ningbo Kangning Hospital, Ningbo, China
| | - Linbo Hu
- Zhejiang Key Laboratory of Pathophysiology, Department of Pharmacology, School of Medicine, Ningbo University, Ningbo, China
| | - Hongde Jiang
- Zhejiang Key Laboratory of Pathophysiology, Department of Pharmacology, School of Medicine, Ningbo University, Ningbo, China
| | - Yibei Dong
- Zhejiang Key Laboratory of Pathophysiology, Department of Pharmacology, School of Medicine, Ningbo University, Ningbo, China
| | - Haowei Shen
- Zhejiang Key Laboratory of Pathophysiology, Department of Pharmacology, School of Medicine, Ningbo University, Ningbo, China.,Key Laboratory of Addiction Research of Zhejiang Province, Ningbo Kangning Hospital, Ningbo, China
| | - Zhongze Lou
- Department of Psychosomatic Medicine, Ningbo First Hospital, Ningbo Hospital of Zhejiang University, Ningbo, China.,Central Laboratory of the Medical Research Center, Ningbo First Hospital, Ningbo Hospital of Zhejiang University, Ningbo, China
| | - Siyu Yang
- Zhejiang Key Laboratory of Pathophysiology, Department of Pharmacology, School of Medicine, Ningbo University, Ningbo, China
| | - Yunxin Ji
- Department of Psychosomatic Medicine, Ningbo First Hospital, Ningbo Hospital of Zhejiang University, Ningbo, China
| | - Liemin Ruan
- Department of Psychosomatic Medicine, Ningbo First Hospital, Ningbo Hospital of Zhejiang University, Ningbo, China
| | - Xiaoqin Zhang
- Zhejiang Key Laboratory of Pathophysiology, Department of Pharmacology, School of Medicine, Ningbo University, Ningbo, China.,Key Laboratory of Addiction Research of Zhejiang Province, Ningbo Kangning Hospital, Ningbo, China
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4
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Lo AC, Rajan N, Gastaldo D, Telley L, Hilal ML, Buzzi A, Simonato M, Achsel T, Bagni C. Absence of RNA-binding protein FXR2P prevents prolonged phase of kainate-induced seizures. EMBO Rep 2021; 22:e51404. [PMID: 33779029 PMCID: PMC8024897 DOI: 10.15252/embr.202051404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 01/26/2021] [Accepted: 01/29/2021] [Indexed: 12/26/2022] Open
Abstract
Status epilepticus (SE) is a condition in which seizures are not self-terminating and thereby pose a serious threat to the patient's life. The molecular mechanisms underlying SE are likely heterogeneous and not well understood. Here, we reveal a role for the RNA-binding protein Fragile X-Related Protein 2 (FXR2P) in SE. Fxr2 KO mice display reduced sensitivity specifically to kainic acid-induced SE. Immunoprecipitation of FXR2P coupled to next-generation sequencing of associated mRNAs shows that FXR2P targets are enriched in genes that encode glutamatergic post-synaptic components. Of note, the FXR2P target transcriptome has a significant overlap with epilepsy and SE risk genes. In addition, Fxr2 KO mice fail to show sustained ERK1/2 phosphorylation induced by KA and present reduced burst activity in the hippocampus. Taken together, our findings show that the absence of FXR2P decreases the expression of glutamatergic proteins, and this decrease might prevent self-sustained seizures.
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Affiliation(s)
- Adrian C Lo
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Nicholas Rajan
- Department of Neurosciences and Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Denise Gastaldo
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Ludovic Telley
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Muna L Hilal
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Andrea Buzzi
- Department of Neuroscience and Rehabilitation, University of Ferrara, Ferrara, Italy
| | - Michele Simonato
- Department of Neuroscience and Rehabilitation, University of Ferrara, Ferrara, Italy.,Division of Neuroscience, IRCCS San Raffaele Hospital, Milan, Italy
| | - Tilmann Achsel
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Claudia Bagni
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,Department of Neurosciences and Leuven Brain Institute, KU Leuven, Leuven, Belgium.,Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
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5
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Effects of 3-Month Exposure to E-Cigarette Aerosols on Glutamatergic Receptors and Transporters in Mesolimbic Brain Regions of Female C57BL/6 Mice. TOXICS 2020; 8:toxics8040095. [PMID: 33137879 PMCID: PMC7712012 DOI: 10.3390/toxics8040095] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/17/2020] [Accepted: 10/22/2020] [Indexed: 12/16/2022]
Abstract
Electronic cigarettes (e-cigs) use has been dramatically increased recently, especially among youths. Previous studies from our laboratory showed that chronic exposure to e-cigs, containing 24 mg/mL nicotine, was associated with dysregulation of glutamate transporters and neurotransmitter levels in the brain of a mouse model. In this study, we evaluated the effect of three months’ continuous exposure to e-cig vapor (JUUL pods), containing a high nicotine concentration, on the expression of glutamate receptors and transporters in drug reward brain regions such as the nucleus accumbens (NAc) core (NAc-core), NAc shell (NAc-shell) and hippocampus (HIP) in female C57BL/6 mice. Three months’ exposure to mint- or mango-flavored JUUL (containing 5% nicotine, 59 mg/mL) induced upregulation of metabotropic glutamate receptor 1 (mGluR1) and postsynaptic density protein 95 (phosphorylated and total PSD95) expression, and downregulation of mGluR5 and glutamate transporter 1 (GLT-1) in the NAc-shell. In addition, three months’ exposure to JUUL was associated with upregulation of mGluR5 and GLT-1 expression in the HIP. These findings demonstrated that three-month exposure to e-cig vapor containing high nicotine concentrations induced differential effects on the glutamatergic system in the NAc and HIP, suggesting dysregulation of glutamatergic system activity in mesolimbic brain regions.
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6
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Yao K, Yang Q, Li Y, Lan T, Yu H, Yu Y. MicroRNA-9 mediated the protective effect of ferulic acid on hypoxic-ischemic brain damage in neonatal rats. PLoS One 2020; 15:e0228825. [PMID: 32470970 PMCID: PMC7259979 DOI: 10.1371/journal.pone.0228825] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 05/13/2020] [Indexed: 01/17/2023] Open
Abstract
Neonatal hypoxic-ischemic brain damage (HIBD) is prone to cognitive and memory impairments, and there is no effective clinical treatment until now. Ferulic acid (FA) is found within members of the genus Angelica, reportedly shows protective effects on neuronal damage. However, the protective effects of FA on HIBD remains unclear. In this study, using the Morris water maze task, we herein found that the impairment of spatial memory formation in adult rats exposed to HIBD was significantly reversed by FA treatment and the administration of LNA-miR-9. The expression of miRNA-9 was detected by RT-PCR analyses, and the results shown that miRNA-9 was significantly increased in the hippocampus of neonatal rats following HIBD and in the PC12 cells following hypoxic-ischemic injury, while FA and LNA-miR-9 both inhibited the expression of miRNA-9, suggesting that the therapeutic effect of FA was mainly attributed to the inhibition of miRNA-9 expression. Indeed, the silencing of miR-9 by LNA-miR-9 or FA similarly attenuated neuronal damage and cerebral atrophy in the rat hippocampus after HIBD, which was consistent with the restored expression levels of brain-derived neurotrophic factor (BDNF). Therefore, our findings indicate that FA treatment may protect against neuronal death through the inhibition of miRNA-9 induction in the rat hippocampus following hypoxic-ischemic damage.
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Affiliation(s)
- Keli Yao
- Department of Histology and Embryology, School of Basic Medical Sciences, Southwest Medical University, Sichuan Province, China
| | - Qin Yang
- Department of Histology and Embryology, School of Basic Medical Sciences, Southwest Medical University, Sichuan Province, China
| | - Yajuan Li
- Department of Histology and Embryology, School of Basic Medical Sciences, Southwest Medical University, Sichuan Province, China
| | - Ting Lan
- Department of Histology and Embryology, School of Basic Medical Sciences, Southwest Medical University, Sichuan Province, China
| | - Hong Yu
- Department of Histology and Embryology, School of Basic Medical Sciences, Southwest Medical University, Sichuan Province, China
- * E-mail: (HY); (YY)
| | - Yang Yu
- Department of Histology and Embryology, School of Basic Medical Sciences, Southwest Medical University, Sichuan Province, China
- * E-mail: (HY); (YY)
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7
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Bekkers JM. Autaptic Cultures: Methods and Applications. Front Synaptic Neurosci 2020; 12:18. [PMID: 32425765 PMCID: PMC7203343 DOI: 10.3389/fnsyn.2020.00018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Accepted: 04/01/2020] [Indexed: 11/13/2022] Open
Abstract
Neurons typically form daisy chains of synaptic connections with other neurons, but they can also form synapses with themselves. Although such self-synapses, or autapses, are comparatively rare in vivo, they are surprisingly common in dissociated neuronal cultures. At first glance, autapses in culture seem like a mere curiosity. However, by providing a simple model system in which a single recording electrode gives simultaneous access to the pre- and postsynaptic compartments, autaptic cultures have proven to be invaluable in facilitating important and elegant experiments in the area of synaptic neuroscience. Here, I provide detailed protocols for preparing and recording from autaptic cultures (also called micro-island or microdot cultures). Variations on the basic procedure are presented, as well as practical tips for optimizing the outcomes. I also illustrate the utility of autaptic cultures by reviewing the types of experiments that have used them over the past three decades. These examples serve to highlight the power and elegance of this simple model system, and will hopefully inspire new experiments for the interrogation of synaptic function.
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Affiliation(s)
- John M Bekkers
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
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8
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Lee J, Kim C, Yeom HD, Nguyen KVA, Eom S, Lee S, Jung JH, Lee JH, Kim SH, Kim IK, Lee JH. Subunit-specific effects of poricoic acid A on NMDA receptors. Pharmacol Rep 2020; 72:472-480. [PMID: 32048268 DOI: 10.1007/s43440-019-00036-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 10/05/2019] [Accepted: 11/05/2019] [Indexed: 11/29/2022]
Abstract
BACKGROUND N-methyl-D-aspartate (NMDA) receptor is a tetrameric protein complex composed of glycine-linked NR1 subunits and glutamate-linked NR2 subunits. There are four NR2 subunits (A-D) that differ in development, anatomy, and function profiles. They play various roles in normal and neuropathologic conditions. Specific agonists, antagonists, and modulators of subunits for selective NMDA receptors may be precious mediational tools and potent agents for treating diseases. The objective of this study was to determine the effect of poricoic acid A on NMDA receptor known to mediate excitatory synaptic transmission factors and cause changes in synaptic strength. Inhibitory effect of poricoic acid A on NR1a combined with NR2A, NR2B, NR2C, or NR2D receptor was evaluated. METHODS Glutamate-mediated currents for each NR1a and NR2 subunits were investigated using two-electrode voltage-clamp techniques. Molecular modeling and molecular dynamics simulation studies were carried out with Autodock Tools. Poricoic acid A and NMDA receptor protein complex were examined with Ligplot and Pymol docking program. Ligplot shows binding activity at the protein and the ligand. RESULTS The inhibitory effect of poricoic acid A on glutamate-induced inward current in a concentration-dependent manner that was reversible. Half inhibitory concentrations of glutamate on NR1a/NR2A, NR1a/NR2B, NR1a/NR2C, and NR1a/NR2D receptors were 9.6 ± 1.2, 5.7 ± 0.4, 46.1 ± 21.5, and 21.5 ± 8.2 μM, respectively. This corresponded to the order of inhibitory effect of oocyte expressing NR1a and NR2s subunit of NR1a/NR2B > NR1a/NR2A > NR1a/NR2C > NR1a/NR2D. CONCLUSIONS Taken together, these results indicate that poricoic acid A can modulate the expression of NMDA receptor. In addition, the regulation of excitatory ligand-gating ion channel by poricoic acid A may have pharmaceutical functions on excitatory synaptic transmission of neuronal system.
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Affiliation(s)
- Jaeeun Lee
- Department of Biotechnology, Chonnam National University, #4-415, Gwangju, 61886, Korea
| | - Chaelin Kim
- Department of Biotechnology, Chonnam National University, #4-415, Gwangju, 61886, Korea
| | - Hye Duck Yeom
- Department of Biotechnology, Chonnam National University, #4-415, Gwangju, 61886, Korea
| | - Khoa V A Nguyen
- Department of Biotechnology, Chonnam National University, #4-415, Gwangju, 61886, Korea
| | - Sanung Eom
- Department of Biotechnology, Chonnam National University, #4-415, Gwangju, 61886, Korea
| | - Shinhui Lee
- Department of Biotechnology, Chonnam National University, #4-415, Gwangju, 61886, Korea
| | - Ji-Hye Jung
- Hygienic Safety and Analysis Center, World Institute of Kimchi, Gwangju, 61755, Korea
| | - Jeong-Ho Lee
- Sunchang Research Institute of Health and Longevity, Sunchang, Jeonbuk, 56015, Korea
| | - Sung Hyun Kim
- Hygienic Safety and Analysis Center, World Institute of Kimchi, Gwangju, 61755, Korea
| | - Il-Kwang Kim
- Nature Cosmeceu Co., Ltd, Jeonbuk Institute for Food -Bioindustry, Jeonju, Jeonbuk, 54810, Korea.
| | - Jun-Ho Lee
- Department of Biotechnology, Chonnam National University, #4-415, Gwangju, 61886, Korea.
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9
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Moldavski A, Behr J, Bading H, Bengtson CP. A novel method using ambient glutamate for the electrophysiological quantification of extrasynaptic NMDA receptor function in acute brain slices. J Physiol 2020; 598:633-650. [PMID: 31876958 DOI: 10.1113/jp278362] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 12/18/2019] [Indexed: 12/30/2022] Open
Abstract
KEY POINTS We present a novel protocol to quantify extrasynaptic NMDA receptor function utilizing the semi-selective activation of extrasynaptic receptors by ambient extracellular glutamate in acute brain slices from adult rats. We use whole cell patch clamp to measure the effect of the NMDA receptor antagonist MK-801 on both synaptic and brief, local agonist application-evoked responses. The level of ambient glutamate was estimated from tonic NMDA receptor activity to be ∼77 nM and an equivalent concentration of NMDA was used to estimate the degree of extrasynaptic blockade (>82%) by our MK-801 protocol. The extrasynaptic component of the total NMDA receptor pool can be mathematically derived from these data and was estimated to be 29-39% in the stratum radiatum of the CA1 region of the rat hippocampus. This technique could be used to quantify extrasynaptic NMDA receptor function in rodent models of diseases where extrasynaptic NMDA receptors are implicated in neuron death. ABSTRACT Synaptic NMDA receptors (NMDARs) play a central role in pro-survival signalling and synaptic plasticity in the majority of excitatory synapses in the central nervous system whereas extrasynaptic NMDARs (ES-NMDARs) activate pro-death pathways and have been implicated in many neurodegenerative diseases. ES-NMDARs have been characterized in acute brain slice preparations using the largely irreversible, activity-dependent NMDAR antagonist MK-801 to block synaptic NMDARs. This approach is limited by the concomitant MK-801 blockade of ES-NMDARs activated by ambient extracellular glutamate, which is largely absent from the synaptic cleft due to the high density of nearby glutamate transporters. In acute hippocampal slices from rats aged 35-42 postnatal days, we estimated ambient glutamate to be 72-83 nM resulting in a block of more than 82% of ES-NMDARs during a 5 min MK-801 application. This paper describes a novel electrophysiological and mathematical method to quantify the proportion of NMDARs located at extrasynaptic locations in a confined region of an acute brain slice preparation using MK-801 to preferentially block ES-NMDARs. The protocol uses whole cell patch clamp measurement of NMDAR responses to synaptic stimulation and brief local pressure application of NMDA before and after MK-801 application. After mathematically correcting for the relative block of both synaptic and extrasynaptic receptors, ES-NMDARs were estimated to comprise 29-39% of the total NMDAR pool in the apical dendrites of hippocampal CA1 pyramidal neurons. This new method may prove useful for accurate quantification of NMDAR distributions in neurodegenerative diseases that are associated with increased toxic ES-NMDAR signalling.
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Affiliation(s)
- Alexander Moldavski
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), Heidelberg University, Heidelberg, Germany.,Clinic for Psychiatry and Psychotherapy, Brandenburg Medical School Theodor Fontane (MHB), Neuruppin, Germany.,Department of Psychiatry and Psychotherapy, Charité Medical University of Berlin, Berlin, Germany
| | - Joachim Behr
- Clinic for Psychiatry and Psychotherapy, Brandenburg Medical School Theodor Fontane (MHB), Neuruppin, Germany.,Department of Psychiatry and Psychotherapy, Charité Medical University of Berlin, Berlin, Germany
| | - Hilmar Bading
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), Heidelberg University, Heidelberg, Germany
| | - C Peter Bengtson
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), Heidelberg University, Heidelberg, Germany
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10
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Modulation of the MAPKs pathways affects Aβ-induced cognitive deficits in Alzheimer's disease via activation of α7nAChR. Neurobiol Learn Mem 2020; 168:107154. [PMID: 31904546 DOI: 10.1016/j.nlm.2019.107154] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 11/17/2019] [Accepted: 12/31/2019] [Indexed: 01/21/2023]
Abstract
Cognitive impairment in Alzheimer's disease (AD) is characterized by being deficient at learning and memory. Aβ1-42 oligomers have been shown to impair rodent cognitive function. We previously demonstrated that activation of α7nAChR, inhibition of p38 or JNK could alleviate Aβ-induced memory deficits in Y maze test. In this study, we investigated whether the effects of α7nAChR and MAPKs on Y maze test is reproducible with a hippocampus-dependent spatial memory test such as Morris water maze. We also assessed the possible co-existence of hippocampus-independent recognition memory dysfunction using a novel object recognition test and an alternative and stress free hippocampus-dependent recognition memory test such as the novel place recognition. Besides, previous research from our lab has shown that MAPKs pathways regulate Aβ internalization through mediating α7nAChR. In our study, whether MAPKs pathways exert their functions in cognition by modulating α7nAChR through regulating glutamate receptors and synaptic protein, remain little known. Our results showed that activation of α7nAChR restored spatial memory, novel place recognition memory, and short-term and long-term memory in novel object recognition. Inhibition of p38 restored spatial memory and short-term and long-term memory in novel object recognition. Inhibition of ERK restored short-term memory in novel object recognition and novel place recognition memory. Inhibition of JNK restored spatial memory, short-term memory in novel object recognition and novel place recognition memory. Beside this, the activation of α7nAChR, inhibition of p38 or JNK restored Aβ-induced levels of NMDAR1, NMDAR2A, NMDAR2B, GluR1, GluR2 and PSD95 in Aβ-injected mice without influencing synapsin 1. In addition, these treatments also recovered the expression of acetylcholinesterase (AChE). Finally, we found that the inhibition of p38 or JNK resulted in the upregulation of α7nAChR mRNA levels in the hippocampus. Our results indicated that inhibition of p38 or JNK MAPKs could alleviate Aβ-induced spatial memory deficits through regulating activation of α7nAChR via recovering memory-related proteins. Moreover, p38, ERK and JNK MAPKs exert different functions in spatial and recognition memory.
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11
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Koster KP, Francesconi W, Berton F, Alahmadi S, Srinivas R, Yoshii A. Developmental NMDA receptor dysregulation in the infantile neuronal ceroid lipofuscinosis mouse model. eLife 2019; 8:40316. [PMID: 30946007 PMCID: PMC6464704 DOI: 10.7554/elife.40316] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Accepted: 03/31/2019] [Indexed: 12/20/2022] Open
Abstract
Protein palmitoylation and depalmitoylation alter protein function. This post-translational modification is critical for synaptic transmission and plasticity. Mutation of the depalmitoylating enzyme palmitoyl-protein thioesterase 1 (PPT1) causes infantile neuronal ceroid lipofuscinosis (CLN1), a pediatric neurodegenerative disease. However, the role of protein depalmitoylation in synaptic maturation is unknown. Therefore, we studied synapse development in Ppt1-/- mouse visual cortex. We demonstrate that the developmental N-methyl-D-aspartate receptor (NMDAR) subunit switch from GluN2B to GluN2A is stagnated in Ppt1-/- mice. Correspondingly, Ppt1-/- neurons exhibit immature evoked NMDAR currents and dendritic spine morphology in vivo. Further, dissociated Ppt1-/- cultured neurons show extrasynaptic, diffuse calcium influxes and enhanced vulnerability to NMDA-induced excitotoxicity, reflecting the predominance of GluN2B-containing receptors. Remarkably, Ppt1-/- neurons demonstrate hyperpalmitoylation of GluN2B as well as Fyn kinase, which regulates surface retention of GluN2B. Thus, PPT1 plays a critical role in postsynapse maturation by facilitating the GluN2 subunit switch and proteostasis of palmitoylated proteins.
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Affiliation(s)
- Kevin P Koster
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, United States
| | - Walter Francesconi
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, United States
| | - Fulvia Berton
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, United States
| | - Sami Alahmadi
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, United States
| | - Roshan Srinivas
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, United States
| | - Akira Yoshii
- Department of Pediatrics, University of Illinois at Chicago, Chicago, United States.,Department of Neurology, University of Illinois at Chicago, Chicago, United States
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12
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Sapkota K, Dore K, Tang K, Irvine M, Fang G, Burnell ES, Malinow R, Jane DE, Monaghan DT. The NMDA receptor intracellular C-terminal domains reciprocally interact with allosteric modulators. Biochem Pharmacol 2018; 159:140-153. [PMID: 30503374 DOI: 10.1016/j.bcp.2018.11.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 11/28/2018] [Indexed: 11/27/2022]
Abstract
N-methyl-d-aspartate receptors (NMDARs) have multiple prominent roles in CNS function but their excessive or insufficient activity contributes to neuropathological/psychiatric disorders. Consequently, a variety of positive and negative allosteric modulators (PAMs and NAMs, respectively) have recently been developed. Although these modulators bind to extracellular domains, in the present report we find that the NMDAR's intracellular C-terminal domains (CTDs) significantly influence PAM/NAM activity. GluN2 CTD deletion robustly affected NAM and PAM activity with both enhancing and inhibiting effects that were compound-specific and NMDAR subunit-specific. In three cases, individual PAMs became NAMs at specific GluN2-truncated receptors. In contrast to GluN2, GluN1 CTD removal only reduced PAM activity of UBP684 and CIQ, and did not affect NAM activity. Consistent with these findings, agents altering phosphorylation state or intracellular calcium levels displayed receptor-specific and compound-specific effects on PAM activity. It is possible that the GluN2's M4 domain transmits intracellular modulatory signals from the CTD to the M1/M4 channel gating machinery and that this site is a point of convergence in the direct or indirect actions of several PAMs/NAMs thus rendering them sensitive to CTD status. Thus, allosteric modulators are likely to have a marked and varied sensitivity to post-translational modifications, protein-protein associations, and intracellular ions. The interaction between PAM activity and NMDAR CTDs appears reciprocal. GluN1 CTD-deletion eliminated UBP684, but not pregnenolone sulfate (PS), PAM activity. And, in the absence of agonists, UBP684, but not PS, was able to promote movement of fluorescently-tagged GluN1-CTDs. Thus, it may be possible to pharmacologically target NMDAR metabotropic activity in the absence of channel activation.
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Affiliation(s)
- Kiran Sapkota
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5800, USA
| | - Kim Dore
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California at San Diego, San Diego, CA 92093-0634, USA
| | - Kang Tang
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5800, USA
| | - Mark Irvine
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK
| | - Guangyu Fang
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK
| | - Erica S Burnell
- School of Chemistry, National University of Ireland Galway, Galway H91TK33, Ireland
| | - Roberto Malinow
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California at San Diego, San Diego, CA 92093-0634, USA
| | - David E Jane
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK
| | - Daniel T Monaghan
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5800, USA.
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13
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Li B, Rex E, Wang H, Qian Y, Ogden AM, Bleakman D, Johnson KW. Pharmacological Modulation of GluK1 and GluK2 by NETO1, NETO2, and PSD95. Assay Drug Dev Technol 2016; 14:131-43. [PMID: 26991362 DOI: 10.1089/adt.2015.689] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The association between the kainate receptors (KARs) GluK1 and GluK2 and the modifying proteins neuropilin- and tolloid-like 1 (NETO1), neuropilin- and tolloid-like 2 (NETO2), and postsynaptic density protein 95 (PSD95) is likely to produce distinct GluK1 and GluK2 pharmacology in postsynaptic neurons. However, little is known about their corresponding modulatory effects on GluK1 and GluK2 activity in high-throughput assays for cell-based drug discovery. Using heterologous cells that potentially mimic the response in native cells in a fluorescence imaging plate reader (FLIPR) assay, we have investigated assays that incorporate (1) coexpression of GluK1 or GluK2 with their modulatory proteins (NETO1, NETO2, PSD95) and/or (2) enablement of assays with physiological concentration of native GluK1 and GluK2 agonist (glutamate) in the absence of an artificial potentiator (e.g., concanavalin A [Con A]). We found that in the absence of Con A, both NETO1 and NETO2 accessory proteins are able to potentiate kainate- and glutamate-evoked GluK1-mediated Ca(2+) influx. We also noted the striking ability of PSD95 to enhance glutamate-stimulated potentiation effects of NETO2 on GluK1 without the need for Con A and with a robust signal that could be utilized for high-throughput FLIPR assays. These experiments demonstrate the utility of heterologous cells coexpressing PSD95/NETO2 with GluK1 or GluK2 in native cell-mimicking heterologous cell systems for high-throughput assays and represent new avenues into the discovery of KAR modulating therapies.
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Affiliation(s)
- Baolin Li
- 1 Neuroscience Discovery, Lilly Corporate Center , Eli Lilly and Company, Indianapolis, Indiana
| | - Elizabeth Rex
- 1 Neuroscience Discovery, Lilly Corporate Center , Eli Lilly and Company, Indianapolis, Indiana
| | - He Wang
- 2 TTx-Reagents-Proteins, Lilly Corporate Center , Eli Lilly and Company, Indianapolis, Indiana
| | - Yuewei Qian
- 2 TTx-Reagents-Proteins, Lilly Corporate Center , Eli Lilly and Company, Indianapolis, Indiana
| | - Ann Marie Ogden
- 1 Neuroscience Discovery, Lilly Corporate Center , Eli Lilly and Company, Indianapolis, Indiana
| | - David Bleakman
- 1 Neuroscience Discovery, Lilly Corporate Center , Eli Lilly and Company, Indianapolis, Indiana
| | - Kirk W Johnson
- 1 Neuroscience Discovery, Lilly Corporate Center , Eli Lilly and Company, Indianapolis, Indiana
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Posttranslational Modifications Regulate the Postsynaptic Localization of PSD-95. Mol Neurobiol 2016; 54:1759-1776. [PMID: 26884267 DOI: 10.1007/s12035-016-9745-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 01/22/2016] [Indexed: 01/08/2023]
Abstract
The postsynaptic density (PSD) consists of a lattice-like array of interacting proteins that organizes and stabilizes synaptic receptors, ion channels, structural proteins, and signaling molecules required for normal synaptic transmission and synaptic function. The scaffolding and hub protein postsynaptic density protein-95 (PSD-95) is a major element of central chemical synapses and interacts with glutamate receptors, cell adhesion molecules, and cytoskeletal elements. In fact, PSD-95 can regulate basal synaptic stability as well as the activity-dependent structural plasticity of the PSD and, therefore, of the excitatory chemical synapse. Several studies have shown that PSD-95 is highly enriched at excitatory synapses and have identified multiple protein structural domains and protein-protein interactions that mediate PSD-95 function and trafficking to the postsynaptic region. PSD-95 is also a target of several signaling pathways that induce posttranslational modifications, including palmitoylation, phosphorylation, ubiquitination, nitrosylation, and neddylation; these modifications determine the synaptic stability and function of PSD-95 and thus regulate the fates of individual dendritic spines in the nervous system. In the present work, we review the posttranslational modifications that regulate the synaptic localization of PSD-95 and describe their functional consequences. We also explore the signaling pathways that induce such changes.
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Rapamycin Effectively Impedes Melamine-Induced Impairments of Cognition and Synaptic Plasticity in Wistar Rats. Mol Neurobiol 2016; 54:819-832. [DOI: 10.1007/s12035-016-9687-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Accepted: 01/05/2016] [Indexed: 01/07/2023]
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16
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Yu M, Zhang Y, Chen X, Zhang T. Antidepressant-like effects and possible mechanisms of amantadine on cognitive and synaptic deficits in a rat model of chronic stress. Stress 2016; 19:104-13. [PMID: 26466744 DOI: 10.3109/10253890.2015.1108302] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The aim of this study was to examine whether amantadine (AMA), as a low-affinity noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist, is able to improve cognitive deficits caused by chronic stress in rats. Male Wistar rats were divided into four groups: control, control + AMA, stress and stress + AMA groups. The chronic stress model combined chronic unpredictable stress (CUS) with isolated feeding. Animals were exposed to CUS continued for 21 days. AMA (25 mg/kg) was administrated p.o. for 20 days from the 4th day of CUS to the 23rd. Weight and sucrose consumption were measured during model establishing period. Spatial memory was evaluated using the Morris water maze (MWM) test. Following MWM testing, both long-term potentiation (LTP) and depotentiation were recorded in the hippocampal CA1 region. NR2B and postsynaptic density protein 95 (PSD-95) proteins were measured by Western-blot analysis. AMA increased weight and sucrose consumption of stressed rats. Spatial memory and reversal learning in stressed rats were impaired relative to controls, whereas AMA significantly attenuated cognitive impairment. AMA also mitigated the chronic stress-induced impairment of hippocampal synaptic plasticity, in which both the LTP and depotentiation were significantly inhibited in stressed rats. Moreover, AMA enhanced the expression of hippocampal NR2B and PSD-95 in stressed rats. The data suggest that AMA may be an effective therapeutic agent for depression-like symptoms and associated cognitive disturbances.
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Affiliation(s)
- Mei Yu
- a College of Life Sciences and Key Laboratory of Bioactive Materials Ministry of Education, Nankai University , Tianjin , PR China
| | - Yuan Zhang
- a College of Life Sciences and Key Laboratory of Bioactive Materials Ministry of Education, Nankai University , Tianjin , PR China
| | - Xiaoyu Chen
- a College of Life Sciences and Key Laboratory of Bioactive Materials Ministry of Education, Nankai University , Tianjin , PR China
| | - Tao Zhang
- a College of Life Sciences and Key Laboratory of Bioactive Materials Ministry of Education, Nankai University , Tianjin , PR China
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17
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Changes in memory and synaptic plasticity induced in male rats after maternal exposure to bisphenol A. Toxicology 2014; 322:51-60. [DOI: 10.1016/j.tox.2014.05.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2014] [Revised: 04/30/2014] [Accepted: 05/01/2014] [Indexed: 11/17/2022]
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18
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Li X, Zhang YY, Chen ZQ, Jiang ZL, Sun L, Xu LH, Yang Y, Zhang YF. D-serine-induced inactivation of NMDA receptors in cultured rat hippocampal neurons expressing NR2A subunits is Ca2+-dependent. CNS Neurosci Ther 2014; 20:951-60. [PMID: 25042179 DOI: 10.1111/cns.12308] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 06/23/2014] [Accepted: 06/27/2014] [Indexed: 11/29/2022] Open
Abstract
AIMS Our previous studies indicate that glycine can inhibit N-methyl-D-aspartate receptor (NMDAR) responses induced by high concentrations of NMDA in rat hippocampal neurons. The present study was designed to observe whether D-serine induces inactivation of NMDARs in cultured rat hippocampal neurons and to investigate the underlying mechanisms of this effect. METHODS Cell culture, whole-cell patch-clamp electrophysiology, Ca(2+) imaging, immunohistochemistry, and Western blot analysis were used. RESULTS We found that the peak current and Ca(2+) influx evoked by 30 μM NMDA were increased by co-application of D-serine, but those evoked by 300 μM NMDA were reduced dose-dependently by co-application of D-serine. However, the inhibitory effect of D-serine on NMDAR responses was reversed by ZnCl2 (30 nM), an inhibitor of the NR2A subunit, but was less influenced by ifenprodil (10 μM), an NR2B inhibitor. In addition, the inhibitory effect of D-serine was not detected in young hippocampal neurons that expressed less of the NR2A subunits and reversed in the presence of 10 mM BAPTA. CONCLUSIONS D-serine can also induce inactivation of NMDARs, the NR2A subunit is required for the induction of this effect, and this inactivation is Ca(2+)-dependent in nature. This action of D-serine is hypothesized to play a neuroprotective role upon a sustained large glutamate insult to the brain.
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Affiliation(s)
- Xia Li
- Department of Neuropharmacology, Institute of Nautical Medicine, Nantong University, Jiangsu, China
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19
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Activation of mGluR5 attenuates NMDA-induced neurotoxicity through disruption of the NMDAR-PSD-95 complex and preservation of mitochondrial function in differentiated PC12 cells. Int J Mol Sci 2014; 15:10892-907. [PMID: 24941251 PMCID: PMC4100187 DOI: 10.3390/ijms150610892] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 05/16/2014] [Accepted: 05/30/2014] [Indexed: 01/05/2023] Open
Abstract
Glutamate-mediated toxicity is implicated in various neuropathologic conditions, and activation of ionotropic and metabotropic glutamate receptors is considered to be the most important mechanism. It has been reported that pharmacological saturation of metabotropic glutamate receptors (mGluRs) can facilitate N-methyl-d-aspartate receptor (NMDAR) related signaling cascades, but the mechanism leading to mGluR-NMDAR interactions in excitotoxic neuronal injury has remained unidentified. In the present study, we investigated the role of mGluR5 in the regulation of N-methyl-d-aspartate (NMDA)-induced excitotoxicity in differentiated PC12 cells. We found that activation of mGluR5 with the specific agonist R,S-2-chloro-5-hydroxyphenylglycine (CHPG) increased cell viability and inhibited lactate dehydrogenase (LDH) release in a dose-dependent manner. CHPG also inhibited an increase in the Bax/Bcl-2 ratio, attenuated cleavage of caspase-9 and caspase-3, and reduced apoptotic cell death after NMDA treatment. The NMDA-induced mitochondrial dysfunction, as indicated by mitochondrial reactive oxygen species (ROS) generation, collapse of mitochondrial membrane potential (MMP), and cytochrome c release, was also partly prevented by CHPG treatment. Furthermore, CHPG blocked the NMDA-induced interaction of NMDAR with postsynaptic density protein-95 (PSD-95), but had no effects on intracellular calcium concentrations. All these results indicated that activation of mGluR5 protects differentiated PC12 cells from NMDA-induced neuronal excitotoxicity by disrupting NMDAR-PSD-95 interaction, which might be an ideal target for investigating therapeutic strategies in various neurological diseases where excitotoxicity may contribute to their pathology.
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20
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Palmitoylation-dependent regulation of glutamate receptors and their PDZ domain-containing partners. Biochem Soc Trans 2013; 41:72-8. [PMID: 23356261 DOI: 10.1042/bst20120223] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In recent years, it has become clear that both AMPA (α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid)- and NMDA (N-methyl-D-aspartate)-type glutamate receptors, and many of their interacting partners, are palmitoylated proteins. Interfering with palmitoylation dramatically affects receptor trafficking and distribution and, in turn, can profoundly alter synaptic transmission. Increased knowledge of synaptic palmitoylation not only will aid our understanding of physiological neuronal regulation, but also may provide insights into, and even novel treatments for, neuropathological conditions. In the present paper, we review recent advances regarding the regulation of ionotropic glutamate receptor trafficking and function by palmitoylation.
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21
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Prenatal stress increased Snk Polo-like kinase 2, SCF β-TrCP ubiquitin ligase and ubiquitination of SPAR in the hippocampus of the offspring at adulthood. Int J Dev Neurosci 2013; 31:560-7. [PMID: 23850969 DOI: 10.1016/j.ijdevneu.2013.06.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 06/30/2013] [Accepted: 06/30/2013] [Indexed: 11/22/2022] Open
Abstract
Exposure to excessive glucocorticoids during fetal development period contributes to later life psychopathology. Prenatal stress decreases dendritic spine density and impair LTP in the hippocampus of rat pups, however, the mechanisms regulating these changes are still unclear. Glutamate receptors are localized in the postsynaptic density. PSD-95 is a postsynaptic scaffolding protein that plays a role in synaptic maturation and regulation of the synaptic strength and plasticity. PSD-95 interacts with other proteins to form the protein networks that promote dendritic spine formation. The present study investigated the effect of prenatal stress on the levels of scaffolding proteins of NMDA receptor in the hippocampus in order to explain how prenatal stress alters the amount of NMDA receptor in the pups' brain. Pregnant rats were randomly assigned to either the prenatal stress (PS) or the control group (C). The pregnant rats in the PS group were restrained in a plexiglas restrainer for 4h/day during the GD 14-21. Control rats were left undisturbed for the duration of their pregnancies. The amount of PSD-95, SPAR, NR2A and NR2B, as well as the levels of Snk Polo-like kinase 2 and the SCF β-TrCP ubiquitin ligase were measured in the hippocampus of the offspring. The results show that prenatal stress induces a reduction in the amount of NR2B and NR2A subunits in the hippocampus of rat pups, parallel to the decrease in PSD-95 and SPAR at P40 and P60. Moreover, prenatal stress increases Snk and β-TrCP in the hippocampus of rat pups, and the timing correlates with the decrease of SPAR and PSD-95. Prenatal stress also induces a significantly increases in the level of ubiquitinated SPAR in the hippocampus of rat pups at adulthood. The results suggest that degradation of SPAR via UPS system may contribute to the loss of PSD-95 and NMDA receptor subunits in the hippocampus of rat pups at adulthood. In conclusion, the present work demonstrates that the developing brain is critically influenced by glucocorticoids, especially during pre- and early postnatal period, which can have long-term effects on brain development. In addition, an involvement of the UPS system in the prenatal stress model has led to a greater understanding of the effects of prenatal stress later on in life.
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22
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The clinical relevance of neuroplasticity in corticostriatal networks during operant learning. Neurosci Biobehav Rev 2013; 37:2071-80. [PMID: 23567518 DOI: 10.1016/j.neubiorev.2013.03.019] [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: 11/28/2012] [Revised: 03/14/2013] [Accepted: 03/27/2013] [Indexed: 11/23/2022]
Abstract
Dopamine and glutamate serve crucial functions in neural plasticity, learning and memory, and addiction. Contemporary theories contend that these two, widely-distributed neurotransmitter systems play an integrative role in motivational and associative information processing. Combined signaling of these systems, particularly through the dopamine (DA) D1 and glutamate (Glu) N-methyl-d-aspartate receptors (NMDAR), triggers critical intracellular signaling cascades that lead to changes in chromatin structure, gene expression, synaptic plasticity, and ultimately behavior. Addictive drugs also induce long-term neuroadaptations at the molecular and genomic levels causing structural changes that alter basic connectivity. Indeed, evidence that drugs of abuse engage D1- and NMDA-mediated neuronal cascades shared with normal reward learning provides one of the most important insights from contemporary studies on the neurobiology of addiction. Such drug-induced neuroadaptations likely contribute to abnormal information processing and behavior, resulting in the poor decision-making, loss of control, and compulsivity that characterize addiction. Such features are also common to many other neuropsychiatric disorders. Behavior problems, construed as difficulties associated with operant learning and behavior, present compelling challenges and unique opportunities for their treatment that require further study. The present review highlights the integrative work of Ann E. Kelley and colleagues, demonstrating a critical role not only for NMDAR, D1 receptors (D1R), and their associated signaling cascades, but also for other Glu receptors and protein synthesis in operant learning throughout a cortico-striatal-limbic network. Recent work has extended the impact of appetitive learning to epigenetic processes. A better understanding of these processes will likely assist in discovering therapeutics to engage neural plasticity-related processes and promote functional behavioral adaptations.
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Naylor DE, Liu H, Niquet J, Wasterlain CG. Rapid surface accumulation of NMDA receptors increases glutamatergic excitation during status epilepticus. Neurobiol Dis 2013; 54:225-38. [PMID: 23313318 DOI: 10.1016/j.nbd.2012.12.015] [Citation(s) in RCA: 141] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 12/20/2012] [Accepted: 12/28/2012] [Indexed: 02/06/2023] Open
Abstract
After 1h of lithium-pilocarpine status epilepticus (SE), immunocytochemical labeling of NMDA receptor NR1 subunits reveals relocation of subunits from the interior to the cell surface of dentate gyrus granule cells and CA3 pyramidal cells. Simultaneously, an increase in NMDA-miniature excitatory postsynaptic currents (mEPSC) as well as an increase in NMDA receptor-mediated tonic currents is observed in hippocampal slices after SE. Mean-variance analysis of NMDA-mEPSCs estimates that the number of functional postsynaptic NMDA receptors per synapse increases 38% during SE, and antagonism by ifenprodil suggests that an increase in the surface representation of NR2B-containing NMDA receptors is responsible for the augmentation of both the phasic and tonic excitatory currents with SE. These results provide a potential mechanism for an enhancement of glutamatergic excitation that maintains SE and may contribute to excitotoxic injury during SE. Therapies that directly antagonize NMDA receptors may be a useful therapeutic strategy during refractory SE.
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Affiliation(s)
- David E Naylor
- Department of Neurology, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, USA; Department of Neurology, Veterans Administration Greater Los Angeles Healthcare System, USA.
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Peng HY, Hsieh MC, Lai CY, Chen GD, Huang YP, Lin TB. Glucocorticoid mediates water avoidance stress-sensitized colon-bladder cross-talk via RSK2/PSD-95/NR2B in rats. Am J Physiol Endocrinol Metab 2012; 303:E1094-106. [PMID: 23125098 DOI: 10.1152/ajpendo.00235.2012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Unexpected environmental and social stimuli could trigger stress. Although coping with stress is essential for survival, long-term stress impacts visceral functions, and therefore, it plays a role in the development and exacerbation of symptoms of gastrointestinal/urogenital disorders. The aim of this study is to characterize the role of corticosterone in stress-sensitized colon-bladder cross-talk, a phenomenon presumed to underlie the comorbidity of functional bowel and bladder disorders. Cystometry and protein/mRNA expression in the lumbosacral dorsal horn (L6-S1) in response to intracolonic mustard oil (MO) instillation were analyzed in female Wistar-Kyoto rats subjected to water avoidance stress (WAS; 1 h/day for 10 days) or sham stress (WAsham). Whereas it had no effect on baseline-voiding function, chronic stress upregulated plasma corticosterone concentration and dorsal horn spinal p90 ribosomal S6 kinase 2 (RSK2) protein/mRNA levels, and RSK2 immunoreactivity colocalized with NeuN-positive neurons. Intracolonic MO dose-dependently decreased intrercontraction intervals and threshold pressure, provoked spinal RSK2 and NR2B phosphorylation, and enhanced PSD-95-RSK2 and PSD-95-NR2B coupling. Intrathecal kaempferol (a RSK2 activation antagonist; 30 min before MO instillation), bilateral adrenalectomy (7 days prior the stress paradigm), and subcutaneous RU-38486 (a glucocorticoid receptor antagonist; 30 min daily before stress sessions), but not RU-28318 (a mineralocorticoid receptor antagonist), attenuated MO-induced bladder hyperactivity, protein phosphorylation, and protein-protein interactions in the WAS group. Our results suggest that stress-associated glucocorticoid release mediates WAS-dependent sensitization of colon-bladder cross-talk via the spinal RSK2/PSD-95/NR2B cascade and offer a possibility for developing pharmacological strategies for the treatment of stress-related pelvic pain.
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MESH Headings
- Adrenal Glands/drug effects
- Adrenal Glands/metabolism
- Animals
- Colon/drug effects
- Colon/metabolism
- Colon/physiopathology
- Corticosterone/antagonists & inhibitors
- Corticosterone/blood
- Disks Large Homolog 4 Protein
- Female
- Gastrointestinal Diseases/etiology
- Gene Expression Regulation/drug effects
- Hormone Antagonists/pharmacology
- Intracellular Signaling Peptides and Proteins/genetics
- Intracellular Signaling Peptides and Proteins/metabolism
- MAP Kinase Signaling System/drug effects
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neurons/drug effects
- Neurons/metabolism
- Neurons/pathology
- Random Allocation
- Rats
- Rats, Inbred WKY
- Receptors, Glucocorticoid/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/genetics
- Receptors, N-Methyl-D-Aspartate/metabolism
- Ribosomal Protein S6 Kinases, 90-kDa/antagonists & inhibitors
- Ribosomal Protein S6 Kinases, 90-kDa/genetics
- Ribosomal Protein S6 Kinases, 90-kDa/metabolism
- Spinal Cord/drug effects
- Spinal Cord/metabolism
- Spinal Cord/pathology
- Stress, Psychological/blood
- Stress, Psychological/metabolism
- Stress, Psychological/physiopathology
- Urinary Bladder/drug effects
- Urinary Bladder/metabolism
- Urinary Bladder/physiopathology
- Urinary Bladder Diseases/etiology
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Affiliation(s)
- Hsien-Yu Peng
- Department of Medicine, Mackay Medical College, New Taipei, Taiwan
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Collingridge GL, Volianskis A, Bannister N, France G, Hanna L, Mercier M, Tidball P, Fang G, Irvine MW, Costa BM, Monaghan DT, Bortolotto ZA, Molnár E, Lodge D, Jane DE. The NMDA receptor as a target for cognitive enhancement. Neuropharmacology 2012; 64:13-26. [PMID: 22796429 DOI: 10.1016/j.neuropharm.2012.06.051] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 06/22/2012] [Accepted: 06/24/2012] [Indexed: 12/31/2022]
Abstract
NMDA receptors (NMDARs) play an important role in neural plasticity including long-term potentiation and long-term depression, which are likely to explain their importance for learning and memory. Cognitive decline is a major problem facing an ageing human population, so much so that its reversal has become an important goal for scientific research and pharmaceutical development. Enhancement of NMDAR function is a core strategy toward this goal. In this review we indicate some of the major ways of potentiating NMDAR function by both direct and indirect modulation. There is good evidence that both positive and negative modulation can enhance function suggesting that a subtle approach correcting imbalances in particular clinical situations will be required. Excessive activation and the resultant deleterious effects will need to be carefully avoided. Finally we describe some novel positive allosteric modulators of NMDARs, with some subunit selectivity, and show initial evidence of their ability to affect NMDAR mediated events. This article is part of a Special Issue entitled 'Cognitive Enhancers'.
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Affiliation(s)
- Graham L Collingridge
- MRC Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, Bristol BS1 3NY, UK.
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Peng HY, Chen GD, Lai CY, Hsieh MC, Lin TB. Spinal SIRPα1-SHP2 interaction regulates spinal nerve ligation-induced neuropathic pain via PSD-95-dependent NR2B activation in rats. Pain 2012; 153:1042-1053. [DOI: 10.1016/j.pain.2012.02.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 12/06/2011] [Accepted: 02/07/2012] [Indexed: 10/28/2022]
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Ho GPH, Selvakumar B, Mukai J, Hester LD, Wang Y, Gogos JA, Snyder SH. S-nitrosylation and S-palmitoylation reciprocally regulate synaptic targeting of PSD-95. Neuron 2011; 71:131-41. [PMID: 21745643 DOI: 10.1016/j.neuron.2011.05.033] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/01/2011] [Indexed: 12/22/2022]
Abstract
PSD-95, a principal scaffolding component of the postsynaptic density, is targeted to synapses by palmitoylation, where it couples NMDA receptor stimulation to production of nitric oxide (NO) by neuronal nitric oxide synthase (nNOS). Here, we show that PSD-95 is physiologically S-nitrosylated. We identify cysteines 3 and 5, which are palmitoylated, as sites of nitrosylation, suggesting a competition between these two modifications. In support of this hypothesis, physiologically produced NO inhibits PSD-95 palmitoylation in granule cells of the cerebellum, decreasing the number of PSD-95 clusters at synaptic sites. Further, decreased palmitoylation, as seen in heterologous cells treated with 2-bromopalmitate or in ZDHHC8 knockout mice deficient in a PSD-95 palmitoyltransferase, results in increased PSD-95 nitrosylation. These data support a model in which NMDA-mediated production of NO regulates targeting of PSD-95 to synapses via mutually competitive cysteine modifications. Thus, differential modification of cysteines may represent a general paradigm in signal transduction.
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Affiliation(s)
- Gary P H Ho
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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28
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Bard L, Groc L. Glutamate receptor dynamics and protein interaction: lessons from the NMDA receptor. Mol Cell Neurosci 2011; 48:298-307. [PMID: 21640188 DOI: 10.1016/j.mcn.2011.05.009] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Revised: 05/17/2011] [Accepted: 05/18/2011] [Indexed: 11/16/2022] Open
Abstract
The plasticity of excitatory glutamate synapses emerged over the last decades as a core cellular mechanism for the encoding and processing of various cognitive functions. This property relies in part on the ability to dynamically adjust the content of glutamate receptors in the postsynaptic membrane. Among these receptors, NMDA receptors (NMDAR), which are composed of two obligatory GluN1 and two regulatory GluN2/3 subunits, play a key role in the induction of many forms of plasticity processes. Understanding how NMDAR subtypes are trafficked and regulated in the synapse has thus captured considerable attention. It has emerged that NMDAR synaptic content relies on an equilibrium between intracellular trafficking and rapid lateral diffusion of the receptor within the synaptic area. Here, we review our current understanding of NMDAR trafficking, mostly the ones at the surface membrane, with a specific focus on the role of interacting PDZ-containing proteins during the journey of NMDAR to and around the synaptic area. The cellular and molecular lessons obtained from examining NMDAR dynamics and regulation by interacting proteins appear to apply to other ionotropic neurotransmitter receptors, and thus shed new light on the modulation of excitatory, inhibitory, and modulatory transmission. This article is part of a Special Issue entitled 'Neuronal Function'.
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Affiliation(s)
- Lucie Bard
- Univ. de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France
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29
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Amico-Ruvio SA, Popescu GK. Stationary gating of GluN1/GluN2B receptors in intact membrane patches. Biophys J 2010; 98:1160-9. [PMID: 20371315 DOI: 10.1016/j.bpj.2009.12.4276] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 11/19/2009] [Accepted: 12/01/2009] [Indexed: 11/30/2022] Open
Abstract
NMDA receptors are heteromeric glutamate-gated channels composed of GluN1 and GluN2 subunits. Receptor isoforms that differ in their GluN2-subunit type (A-D) are expressed differentially throughout the central nervous system and have distinct kinetic properties in recombinant systems. How specific receptor isoforms contribute to the functions generally attributed to NMDA receptors remains unknown, due in part to the incomplete functional characterization of individual receptor types and unclear molecular composition of native receptors. We examined the stationary gating kinetics of individual rat recombinant GluN1/GluN2B receptors in cell-attached patches of transiently transfected HEK293 cells and used kinetic analyses and modeling to describe the full range of this receptor's gating behaviors. We found that, like GluN1/GluN2A receptors, GluN1/GluN2B receptors have three gating modes that are distinguishable by their mean open durations. However, for GluN1/GluN2B receptors, the modes also differed markedly in their mean closed durations and thus generated a broader range of open probabilities. We also found that regardless of gating mode, glutamate dissociation occurred approximately 4-fold more slowly (k(-) = 15 s(-1)) compared to that observed in GluN1/GluN2A receptors. On the basis of these results, we suggest that slow glutamate dissociation and modal gating underlie the long heterogeneous activations of GluN1/GluN2B receptors.
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Affiliation(s)
- Stacy A Amico-Ruvio
- Department of Biochemistry, State University of New York at Buffalo, Buffalo, New York, USA
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Korinek M, Sedlacek M, Cais O, Dittert I, Vyklicky L. Temperature dependence of N-methyl-D-aspartate receptor channels and N-methyl-D-aspartate receptor excitatory postsynaptic currents. Neuroscience 2009; 165:736-48. [PMID: 19883737 DOI: 10.1016/j.neuroscience.2009.10.058] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 10/27/2009] [Accepted: 10/27/2009] [Indexed: 11/18/2022]
Abstract
N-methyl-d-aspartate (NMDA) receptors (NMDARs) are highly expressed in the CNS and mediate the slow component of excitatory transmission. The present study was aimed at characterizing the temperature dependence of the kinetic properties of native NMDARs, with special emphasis on the deactivation of synaptic NMDARs. We used patch-clamp recordings to study synaptic NMDARs at layer II/III pyramidal neurons of the rat cortex, recombinant GluN1/GluN2B receptors expressed in human embryonic kidney (HEK293) cells, and NMDARs in cultured hippocampal neurons. We found that time constants characterizing the deactivation of NMDAR-mediated excitatory postsynaptic currents (EPSCs) were similar to those of the deactivation of responses to a brief application of glutamate recorded under conditions of low NMDAR desensitization (whole-cell recording from cultured hippocampal neurons). In contrast, the deactivation of NMDAR-mediated responses exhibiting a high degree of desensitization (outside-out recording) was substantially faster than that of synaptic NMDA receptors. The time constants characterizing the deactivation of synaptic NMDARs and native NMDARs activated by exogenous glutamate application were only weakly temperature sensitive (Q(10)=1.7-2.2), in contrast to those of recombinant GluN1/GluN2B receptors, which are highly temperature sensitive (Q(10)=2.7-3.7). Ifenprodil reduced the amplitude of NMDAR-mediated EPSCs by approximately 50% but had no effect on the time course of deactivation. Analysis of GluN1/GluN2B responses indicated that the double exponential time course of deactivation reflects mainly agonist dissociation and receptor desensitization. We conclude that the temperature dependences of native and recombinant NMDAR are different; in addition, we contribute to a better understanding of the molecular mechanism that controls the time course of NMDAR-mediated EPSCs.
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Affiliation(s)
- M Korinek
- Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic
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31
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PSD-95 regulates D1 dopamine receptor resensitization, but not receptor-mediated Gs-protein activation. Cell Res 2009; 19:612-24. [PMID: 19274064 DOI: 10.1038/cr.2009.30] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The present study aims to define the role of postsynaptic density (PSD)-95 in the regulation of dopamine (DA) receptor function. We found that PSD-95 physically associates with either D(1) or D(2) DA receptors in co-transfected HEK-293 cells. Stimulation of DA receptors altered the association between D(1) receptor and PSD-95 in a time-dependent manner. Functional assays indicated that PSD-95 co-expression did not affect D(1) receptor-stimulated cAMP production, Gs-protein activation or receptor desensitization. However, PSD-95 accelerated the recovery of internalized membrane receptors by promoting receptor recycling, thus resulting in enhanced resensitization of internalized D(1) receptors. Our results provide a novel mechanism for regulating DA receptor recycling that may play an important role in postsynaptic DA functional modulation and synaptic neuroplasticity.
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Activation of protein kinase C enhances NMDA-induced currents in primary cultured cerebellar granule cells: Effect of temperature and NMDA NR2 subunit composition. Eur J Pharmacol 2008; 599:1-10. [DOI: 10.1016/j.ejphar.2008.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2008] [Revised: 07/28/2008] [Accepted: 08/08/2008] [Indexed: 11/23/2022]
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Surface trafficking of N-methyl-D-aspartate receptors: physiological and pathological perspectives. Neuroscience 2008; 158:4-18. [PMID: 18583064 DOI: 10.1016/j.neuroscience.2008.05.029] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 05/06/2008] [Accepted: 05/17/2008] [Indexed: 11/20/2022]
Abstract
The N-methyl-D-aspartate receptor (NMDAR) plays a crucial role in shaping the strength of synaptic connections. Over the last decades, extensive studies have defined the cellular and molecular mechanisms by which synaptic NMDARs control the maturation and plasticity of synaptic transmission, and how altered synaptic NMDAR signaling is implicated in neurodegenerative and psychiatric disorders. It is now clear that activation of synaptic or extrasynaptic NMDARs produces different signaling cascades and thus neuronal functions. Our current understanding of NMDAR surface distribution and trafficking is only emerging. Exchange of NMDARs between synaptic and extrasynaptic areas through surface diffusion is a highly dynamic and regulated process. The aim of this review is to describe the identified mechanisms that regulate surface NMDAR behaviors and discuss the impact of this new trafficking pathway on the well-established NMDAR-dependent physiological and pathophysiological processes.
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Kimura R, Matsuki N. Protein kinase CK2 modulates synaptic plasticity by modification of synaptic NMDA receptors in the hippocampus. J Physiol 2008; 586:3195-206. [PMID: 18483072 DOI: 10.1113/jphysiol.2008.151894] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Synaptic plasticity is the foundation of learning and memory. The protein kinase CK2 phosphorylates many proteins related to synaptic plasticity, but whether it is directly involved in it has not been clarified. Here, we examined the role of CK2 in synaptic plasticity in hippocampal slices using the CK2 selective inhibitors 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) and 4,5,6,7-tetrabromobenzotriazole (TBB). These significantly inhibited N-methyl-D-aspartate (NMDA) receptor-dependent long-term potentiation (LTP). DRB also inhibited NMDA receptor-mediated synaptic transmission, while leaving NMDA receptor-independent LTP unaffected. NMDA receptors thus appear to be the primary targets of CK2. Although both long-term depression (LTD) and LTP are induced by the influx of Ca(2+) through NMDA receptors, surprisingly, LTD was not affected by CK2 inhibitors. We postulated that the LTP-selective modulation by CK2 is due to selective modulation of NMDA receptors, and tested two hypotheses concerning the modulation of NMDA receptors: (i) CK2 selectively modulates NR2A subunits possibly related to LTP, but not NR2B subunits possibly related to LTD; and (ii) CK2 selectively affects synaptic but not extrasynaptic NMDA receptors whose activation is sufficient to induce LTD. DRB decreased NMDA receptor-mediated synaptic transmission in the presence of selective NR2A subunit antagonist. The former hypothesis thus appears unlikely to be correct. However, DRB decreased synaptic NMDA receptor responses in cultured hippocampal neurons without affecting extrasynaptic NMDA receptor current. These findings support the latter hypothesis, that CK2 selectively affects LTP by selective modification of synaptic NMDA receptors in a receptor-location-specific manner.
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Affiliation(s)
- Rie Kimura
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan
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35
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Sornarajah L, Vasuta OC, Zhang L, Sutton C, Li B, El-Husseini A, Raymond LA. NMDA receptor desensitization regulated by direct binding to PDZ1-2 domains of PSD-95. J Neurophysiol 2008; 99:3052-62. [PMID: 18400955 DOI: 10.1152/jn.90301.2008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Regulation of N-methyl-d-aspartate receptor (NMDAR) activity by desensitization is important in physiological and pathological states; NMDAR desensitization contributes in shaping synaptic responses and may be protective by limiting calcium influx during sustained glutamate insults. We previously reported that glycine-independent desensitization decreases during hippocampal neuronal development, correlating with NMDAR synaptic localization and association with postsynaptic density 95 (PSD-95). PSD-95/Discs large/zona occludens (PDZ)-1,2 domains of PSD-95 bind to the C-terminus of NMDAR NR2 subunits. The role of PSD-95 in anchoring signaling proteins near NMDARs is well documented. To determine if PSD-95-induced changes in NMDAR desensitization occur because of direct binding to NR2 or due to recruitment of regulatory proteins, we tested the effects of various PSD-95 constructs on NMDAR currents in human embryonic kidney 293 (HEK293) cells and neurons. In HEK cells, wild-type PSD-95 significantly reduced wild-type NMDAR desensitization without altering currents of NMDARs containing NR2A-S1462A, a mutation that abolishes PSD-95 binding. The PSD-95 N-terminus truncated after the PDZ1-2 domains was sufficient for this effect in neurons with low endogenous PSD-95 levels; in NMDAR-expressing HEK cells, the effect persisted when PSD-95 multimerization was eliminated. Moreover other PSD-95 family members with highly homologous PDZ1-2 domains significantly reduced NMDAR desensitization. In mature neurons, disruption of PSD-95/NMDAR interaction through protein kinase C (PKC) activation increased desensitization to levels found in immature neurons, and this effect was not due to PKC direct regulation of NMDAR activity. We conclude that direct binding of PSD-95 increases stability of NMDAR responses to agonist exposure in neuronal and nonneuronal cells.
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Affiliation(s)
- Lavan Sornarajah
- Graduate Program in Neuroscience, University of British Columbia, 4N3-2255 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada
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36
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Keith D, El-Husseini A. Excitation Control: Balancing PSD-95 Function at the Synapse. Front Mol Neurosci 2008; 1:4. [PMID: 18946537 DOI: 10.3389/neuro.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Accepted: 01/30/2008] [Indexed: 05/19/2023] Open
Abstract
Excitability of individual neurons dictates the overall excitation in specific brain circuits. This process is thought to be regulated by molecules that regulate synapse number, morphology and strength. Neuronal excitation is also influenced by the amounts of neurotransmitter receptors and signaling molecules retained at particular synaptic sites. Recent studies revealed a key role for PSD-95, a scaffolding molecule enriched at glutamatergic synapses, in modulation of clustering of several neurotransmitter receptors, adhesion molecules, ion channels, cytoskeletal elements and signaling molecules at postsynaptic sites. In this review we will highlight mechanisms that control targeting of PSD-95 at the synapse, and discuss how this molecule influences the retention and clustering of diverse synaptic proteins to regulate synaptic structure and strength. We will also discuss how PSD-95 may maintain a balance between excitation and inhibition in the brain and how alterations in this balance may contribute to neuropsychiatric disorders.
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Affiliation(s)
- Dove Keith
- Department of Psychiatry and the Brain Research Centre, University of British Columbia Vancouver, BC, Canada
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37
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38
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Tu S, Shin Y, Zago WM, States BA, Eroshkin A, Lipton SA, Tong GG, Nakanishi N. Takusan: a large gene family that regulates synaptic activity. Neuron 2007; 55:69-85. [PMID: 17610818 PMCID: PMC2902460 DOI: 10.1016/j.neuron.2007.06.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2006] [Revised: 04/11/2007] [Accepted: 06/12/2007] [Indexed: 10/23/2022]
Abstract
We have characterized a rodent-specific gene family designated alpha-takusan (meaning "many" in Japanese). We initially identified a member of the family whose expression is upregulated in mice lacking the NMDAR subunit NR3A. We then isolated cDNAs encoding 46 alpha-takusan variants from mouse brains. Most variants share an approximately 130 aa long sequence, which contains the previously identified domain of unknown function 622 (DUF622) and is predicted to form coiled-coil structures. Single-cell PCR analyses indicate that one neuron can express multiple alpha-takusan variants and particular variants may predominate in certain cell types. Forced expression in cultured hippocampal neurons of two variants, alpha1 or alpha2, which bind either directly or indirectly to PSD-95, leads to an increase in PSD-95 clustering, dendritic spine density, GluR1 surface expression, and AMPAR activity. Conversely, treating cultured neurons with RNAi targeting alpha-takusan variants resulted in the opposite phenotype. Hence, alpha-takusan represents a large gene family that regulates synaptic activity.
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Affiliation(s)
- Shichun Tu
- Center for Neuroscience and Aging, Burnham Institute for Medical Research, La Jolla, CA 92037
| | - Yeonsook Shin
- Center for Neuroscience and Aging, Burnham Institute for Medical Research, La Jolla, CA 92037
- Dept of Molecular Pharmacology, Kanazawa University Graduate School of Medicine, Kanazawa, Ishikawa 920-8640, Japan
| | - Wagner M. Zago
- Center for Neuroscience and Aging, Burnham Institute for Medical Research, La Jolla, CA 92037
| | - Bradley A. States
- Center for Neuroscience and Aging, Burnham Institute for Medical Research, La Jolla, CA 92037
| | - Alexey Eroshkin
- Bioinformatics Shared Resource, Burnham Institute for Medical Research, La Jolla, CA 92037
| | - Stuart A. Lipton
- Center for Neuroscience and Aging, Burnham Institute for Medical Research, La Jolla, CA 92037
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093
| | - Gary G. Tong
- Center for Neuroscience and Aging, Burnham Institute for Medical Research, La Jolla, CA 92037
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093
| | - Nobuki Nakanishi
- Center for Neuroscience and Aging, Burnham Institute for Medical Research, La Jolla, CA 92037
- Correspondence:
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39
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Synaptic trafficking of glutamate receptors by MAGUK scaffolding proteins. Trends Cell Biol 2007; 17:343-52. [PMID: 17644382 DOI: 10.1016/j.tcb.2007.07.005] [Citation(s) in RCA: 218] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Revised: 05/08/2007] [Accepted: 07/04/2007] [Indexed: 11/27/2022]
Abstract
Synaptic transmission underlies every aspect of brain function. Excitatory synapses, which release the neurotransmitter glutamate, are the most numerous type of synapse in the brain. The trafficking of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-type glutamate receptors to and from these synapses controls the strength of excitatory synaptic transmission. However, the underlying mechanisms controlling this trafficking have remained elusive. Recent studies, drawing from advances in molecular biology and electrophysiology techniques, have established an essential role for a family of synaptic scaffolding molecules, known as membrane associate guanylate kinases (MAGUKs), in this trafficking process. These studies highlight the remarkable orchestration of AMPA-type glutamate receptor synaptic trafficking by multiple MAGUKs at different synapses within the same neuron and at different developmental stages.
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40
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Lau CG, Zukin RS. NMDA receptor trafficking in synaptic plasticity and neuropsychiatric disorders. Nat Rev Neurosci 2007; 8:413-26. [PMID: 17514195 DOI: 10.1038/nrn2153] [Citation(s) in RCA: 857] [Impact Index Per Article: 50.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The number and subunit composition of synaptic N-methyl-D-aspartate receptors (NMDARs) are not static, but change in a cell- and synapse-specific manner during development and in response to neuronal activity and sensory experience. Neuronal activity drives not only NMDAR synaptic targeting and incorporation, but also receptor retrieval, differential sorting into the endosomal-lysosomal pathway and lateral diffusion between synaptic and extrasynaptic sites. An emerging concept is that activity-dependent, bidirectional regulation of NMDAR trafficking provides a dynamic and potentially powerful mechanism for the regulation of synaptic efficacy and remodelling, which, if dysregulated, can contribute to neuropsychiatric disorders such as cocaine addiction, Alzheimer's disease and schizophrenia.
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Affiliation(s)
- C Geoffrey Lau
- Rose F. Kennedy Center for Research in Mental Retardation and Developmental Disabilities, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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41
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Halbach A, Mörgelin M, Baumgarten M, Milbrandt M, Paulsson M, Plomann M. PACSIN 1 forms tetramers via its N-terminal F-BAR domain. FEBS J 2007; 274:773-82. [PMID: 17288557 DOI: 10.1111/j.1742-4658.2006.05622.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ability of protein kinase C and casein kinase 2 substrate in neurons (PACSIN)/syndapin proteins to self-polymerize is crucial for the simultaneous interactions with more than one Src homology 3 domain-binding partner or with lipid membranes. The assembly of this network has profound effects on the neural Wiskott-Aldrich syndrome protein-mediated attachment of the actin polymerization machinery to vesicle membranes as well as on the movement of the corresponding vesicles. Also, the sensing of vesicle membranes and/or the induction of membrane curvature are more easily facilitated in the presence of larger PACSIN complexes. The N-terminal Fes-CIP homology and Bin-Amphiphysin-Rvs (F-BAR) domains of several PACSIN-related proteins have been shown to mediate self-interactions, whereas studies using deletion mutants derived from closely related proteins led to the view that oligomerization depends on the formation of a trimeric complex via a coiled-coil region present in these molecules. To address whether the model of trimeric complex formation is applicable to PACSIN 1, the protein was recombinantly expressed and tested in four different assays for homologous interactions. The results showed that PACSIN 1 forms tetramers of about 240 kDa, with the self-interaction having a K(D) of 6.4 x 10(-8) M. Ultrastructural analysis of these oligomers after negative staining showed that laterally arranged PACSIN molecules bind to each other via a large globular domain and form a barrel-like structure. Together, these results demonstrate that the N-terminal F-BAR domain of PACSIN 1 forms the contact site for a tetrameric structure, which is able to simultaneously interact with multiple Src homology 3 binding partners.
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Affiliation(s)
- Arndt Halbach
- Center for Biochemistry and Center for Molecular Medicine, Medical Faculty, University of Cologne, Germany
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42
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von Engelhardt J, Coserea I, Pawlak V, Fuchs EC, Köhr G, Seeburg PH, Monyer H. Excitotoxicity in vitro by NR2A- and NR2B-containing NMDA receptors. Neuropharmacology 2007; 53:10-7. [PMID: 17570444 DOI: 10.1016/j.neuropharm.2007.04.015] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 03/24/2007] [Accepted: 04/04/2007] [Indexed: 11/24/2022]
Abstract
Excitotoxicity, exacerbating acute brain damage from brain trauma or stroke, is mediated in part by excessive Ca(2+)-influx from prolonged NMDA receptor activation. However, the contribution to excitotoxicity by each of the main NMDAR subtypes in glutamatergic forebrain neurons, the NR2A- and NR2B-types, has remained enigmatic. Here, we investigated this issue by use of pharmacological and genetic tools in cultured cortical neurons. In wild-type neurons the contribution of the NMDA receptor subtypes to excitotoxicity changed with the age of the cultures. The blockade of NR2B-containing NMDA receptors prevented NMDA-mediated toxicity in young cultures after 14days in vitro (DIV14), but both subtypes triggered excitotoxicity in older (DIV21) cultures. Notably, blocking either of the two subtypes failed to prevent NMDA-elicited cell death, indicating that the remaining subtype triggers cell demise. Intriguingly, a neuroprotective aspect of the NR2A subtype became apparent at submaximal NMDA concentration only at DIV21. The NR2A subtype mediated NMDA toxicity as well as partial protection only if it carried a functional C-terminal domain. Upon deletion of this domain in the NR2A subtype, excitotoxicity was mediated entirely via the NR2B subtype, both at DIV14 and DIV21. Our findings predict that successful therapeutic intervention in stroke based on currently available NMDA receptor subtype-selective blockers is unlikely.
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Affiliation(s)
- Jakob von Engelhardt
- IZN and Department of Clinical Neurobiology, University Hospital of Neurology, INF 364, 69120 Heidelberg, Germany
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43
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Lin Y, Jover-Mengual T, Wong J, Bennett MVL, Zukin RS. PSD-95 and PKC converge in regulating NMDA receptor trafficking and gating. Proc Natl Acad Sci U S A 2006; 103:19902-7. [PMID: 17179037 PMCID: PMC1750863 DOI: 10.1073/pnas.0609924104] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neuronal NMDA receptors (NMDARs) colocalize with postsynaptic density protein-95 (PSD-95), a putative NMDAR anchoring protein and core component of the PSD, at excitatory synapses. PKC activation and PSD-95 expression each enhance NMDAR channel opening rate and number of functional channels at the cell surface. Here we show in Xenopus oocytes that PSD-95 and PKC potentiate NMDA gating and trafficking in a nonadditive manner. PSD-95 and PKC each enhance NMDA channel activity, with no change in single-channel conductance, reversal potential or mean open time. PSD-95 and PKC each potentiate NMDA channel opening rate (k(beta)) and number of functional channels at the cell surface (N), as indicated by more rapid current decay and enhanced charge transfer in the presence of the open channel blocker MK-801. PSD-95 and PKC each increase NMDAR surface expression, as indicated by immunofluorescence. PKC potentiates NMDA channel function and NMDAR surface expression to the same final absolute values in the absence or presence of PSD-95. Thus, PSD-95 partially occludes PKC potentiation. We further show that Ser-1462, a putative phosphorylation target within the PDZ-binding motif of the NR2A subunit, is required for PSD-95-induced potentiation and partial occlusion of PKC potentiation. Coimmunoprecipitation experiments with cortical neurons in culture indicate that PKC activation promotes assembly of NR2 with NR1, and that the newly assembled NMDARs are not associated with PSD-95. These findings predict that synaptic scaffolding proteins and protein kinases convergently modulate NMDAR gating and trafficking at synaptic sites.
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Affiliation(s)
- Ying Lin
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Teresa Jover-Mengual
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Judy Wong
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Michael V. L. Bennett
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
- *To whom correspondence may be addressed. E-mail:
or
| | - R. Suzanne Zukin
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
- *To whom correspondence may be addressed. E-mail:
or
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44
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Groc L, Heine M, Cousins SL, Stephenson FA, Lounis B, Cognet L, Choquet D. NMDA receptor surface mobility depends on NR2A-2B subunits. Proc Natl Acad Sci U S A 2006; 103:18769-74. [PMID: 17124177 PMCID: PMC1693737 DOI: 10.1073/pnas.0605238103] [Citation(s) in RCA: 266] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Indexed: 11/18/2022] Open
Abstract
The NR2 subunit composition of NMDA receptors (NMDARs) varies during development, and this change is important in NMDAR-dependent signaling. In particular, synaptic NMDAR switch from containing mostly NR2B subunit to a mixture of NR2B and NR2A subunits. The pathways by which neurons differentially traffic NR2A- and NR2B-containing NMDARs are poorly understood. Using single-particle and -molecule approaches and specific antibodies directed against NR2A and NR2B extracellular epitopes, we investigated the surface mobility of native NR2A and NR2B subunits at the surface of cultured neurons. The surface mobility of NMDARs depends on the NR2 subunit subtype, with NR2A-containing NMDARs being more stable than NR2B-containing ones, and NR2A subunit overexpression stabilizes surface NR2B-containing NMDARs. The developmental change in the synaptic surface content of NR2A and NR2B subunits was correlated with a developmental change in the time spent by the subunits within synapses. This suggests that the switch in synaptic NMDAR subtypes depends on the regulation of the receptor surface trafficking.
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Affiliation(s)
- Laurent Groc
- Physiologie Cellulaire de la Synapse, Unité Mixte de Recherche (UMR) 5091, Centre National de la Recherche Scientifique (CNRS), Université Bordeaux 2, 33077 Bordeaux, France.
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Kim E, Ko J. Molecular organization and assembly of the postsynaptic density of excitatory brain synapses. Results Probl Cell Differ 2006; 43:1-23. [PMID: 17068965 DOI: 10.1007/400_011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
The postsynaptic density (PSD) is a postsynaptic membrane specialization at excitatory synapses. The PSD is made of macromolecular multiprotein complexes, which contain a variety of synaptic proteins including membrane, scaffolding, and signaling proteins. By coaggregating with postsynaptic cell adhesion molecules, PSD proteins promote the formation and maturation of excitatory synapses. PSD proteins organize signaling pathways to coordinate structural and functional changes in synapses, and they regulate trafficking and recycling of glutamate receptors, which determines synaptic strength and plasticity. Synaptic activity dynamically regulates the assembly of the PSD through mechanisms including protein phosphorylation, palmitoylation, and protein degradation. PSD proteins associate with diverse motor proteins, suggesting that they function as adaptors linking motors to their specific cargoes.
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Affiliation(s)
- Eunjoon Kim
- National Creative Research Initiative Center for Synaptogenesis and Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon.
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Dong YN, Wu HY, Hsu FC, Coulter DA, Lynch DR. Developmental and cell-selective variations in N-methyl-D-aspartate receptor degradation by calpain. J Neurochem 2006; 99:206-17. [PMID: 16899064 PMCID: PMC2483508 DOI: 10.1111/j.1471-4159.2006.04096.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
NMDA receptors play critical roles in synaptic modulation and neurological disorders. In this study, we investigated the developmental changes in NR2 cleavage by NMDA receptor-activated calpain in cultured cortical and hippocampal neurons. Calpain activity increased with development, associated with increased expression of NMDA receptors but not of calpain I. The activation of calpain in immature and mature cortical cultures was inhibited by antagonists of NR1/2B and NR1/2A/2B receptors, whereas the inhibition of NR1/2B receptors did not alter calpain activation in mature hippocampal cultures. The degradation of NR2 subunits by calpain differed with developmental age. NR2A was not a substrate of calpain in mature hippocampal cultures, but was cleaved in immature cortical and hippocampal cultures. NR2B degradation by calpain in cortical cultures decreased with development, but the level of degradation of NR2B in hippocampal cultures did not change. The kinetics of NMDA receptor-gated whole cell currents were also modulated by calpain activation in a manner that varied with developmental stage in vitro. In early (but not later) developmental stages, calpain activation altered the NMDA-evoked current rise time and time constants for both desensitization and deactivation. Our data suggest that the susceptibility of the NMDA receptor to cleavage by calpain varies with neuronal maturity in a manner that may alter its electrophysiological properties.
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Affiliation(s)
- Yi Na Dong
- Department of Neurology and Pediatrics, University of Pennsylvania and the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104-4318, USA
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Köhr G. NMDA receptor function: subunit composition versus spatial distribution. Cell Tissue Res 2006; 326:439-46. [PMID: 16862427 DOI: 10.1007/s00441-006-0273-6] [Citation(s) in RCA: 254] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Accepted: 06/08/2006] [Indexed: 11/27/2022]
Abstract
NMDA receptors (NMDARs) play a pivotal role in the regulation of neuronal communication and synaptic function in the central nervous system. The subunit composition and compartmental localization of NMDARs in neurons affect channel activity and downstream signaling. This review discusses the distinct NMDAR subtypes and their function at synaptic, perisynaptic, and extrasynaptic sites of excitatory and inhibitory neurons. Many neurons express more than one of the modulatory NR2 subunits that participate in the formation of di- and/or triheteromeric channel assemblies (e.g., NR1/NR2A, NR1/NR2B, and/or NR1/NR2A/NR2B). Depending on the subunit composition and presence or absence of intracellular binding partners along the postsynaptic membrane, these NMDAR subtypes are allocated to distinct synaptic inputs converging onto a neuron or are distributed differentially among synaptic or extrasynaptic sites. These sites can carry NR2A and NR2B subunits, supporting the hypothesis that the spatial distribution of scaffolding and signaling complexes critically determines the full spectrum of NMDAR signaling.
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Affiliation(s)
- Georg Köhr
- Department of Molecular Neurobiology, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany.
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Groc L, Gustafsson B, Hanse E. AMPA signalling in nascent glutamatergic synapses: there and not there! Trends Neurosci 2006; 29:132-9. [PMID: 16443288 DOI: 10.1016/j.tins.2006.01.005] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2005] [Revised: 11/24/2005] [Accepted: 01/12/2006] [Indexed: 11/30/2022]
Abstract
Nascent glutamatergic synapses are thought to be equipped with only NMDA receptors and to mature in a stepwise fashion when AMPA receptors are acquired later, through specific patterns of activity. We review recent data suggesting that AMPA receptors are in fact present in the nascent synapse but in a labile state. The nascent synapse can easily switch between AMPA-signalling and AMPA-silent states in a manner not requiring activation of NMDA receptors or metabotropic glutamate receptors. NMDA receptor activation by correlated presynaptic and postsynaptic activity can switch the nascent synapse to a mature, more stable state, in which AMPA receptor signalling is modified only through conventional plasticity processes. Thus, the AMPA receptor silence of nascent glutamatergic synapses depends on the synaptic activation history rather than on the nascent state itself.
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Affiliation(s)
- Laurent Groc
- Physiologie Cellulaire de la Synapse, CNRS-UMR 5091, Université Bordeaux 2, 33077 Bordeaux, France.
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Alele PE, Devaud LL. Differential adaptations in GABAergic and glutamatergic systems during ethanol withdrawal in male and female rats. Alcohol Clin Exp Res 2005; 29:1027-34. [PMID: 15976529 DOI: 10.1097/01.alc.0000167743.96121.40] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND There are significant and consistent sex differences in recovery from ethanol withdrawal in our animal model of ethanol dependence. We have also observed significant and varied sex differences in subunit protein levels of gamma-aminobutyric acid A (GABAA) and the N-metheyl-D-aspartate subtype of glutamate receptors occurring with ethanol dependence and withdrawal. Considering the major role of these two systems as targets of ethanol, we wanted to explore additional possible mechanisms underlying changes in GABAergic and glutamatergic responses after chronic ethanol exposure. Therefore, the objective of the present study was to examine GABAergic- and glutamatergic-associated proteins at three days of ethanol withdrawal, when female rats appear to have largely recovered but male rats still display robust signs of withdrawal. METHODS Male and female rats were fed 6% ethanol in a nutritionally complete liquid diet for 14 days according to a pair-fed design; withdrawal was initiated by replacement of the diet with chow. At three days of withdrawal, the cerebral cortex and hippocampus were dissected for use in Western blot analysis. The paired design was maintained throughout all experimental procedures. RESULTS At three days of ethanol withdrawal, we found region-specific and sex-selective alterations in levels of GAD (glutamic acid decarboxylase, GABA synthetic enzyme), GABA and glutamate transporters, and the synapse-associated proteins HSP70, PSD-95, and synaptophysin. There were also several significant differences in transporter function at this time that varied between males and females. CONCLUSIONS Taken together, these findings show differential adaptations of GABAergic and glutamatergic neurotransmission between female and male rats that are associated with withdrawal recovery. This suggests that selective withdrawal-induced neuroadaptations in regulation of these systems' activities underlie, at least in part, sex differences in withdrawal recovery between male and female rats.
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Affiliation(s)
- P E Alele
- Department of Pharmaceutical Sciences, Idaho State University, Pocatello, Idaho 83209, USA
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Kristiansen LV, Meador-Woodruff JH. Abnormal striatal expression of transcripts encoding NMDA interacting PSD proteins in schizophrenia, bipolar disorder and major depression. Schizophr Res 2005; 78:87-93. [PMID: 16023328 DOI: 10.1016/j.schres.2005.06.012] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Revised: 06/07/2005] [Accepted: 06/13/2005] [Indexed: 11/30/2022]
Abstract
Previous studies have described abnormal expression of molecules involved in glutamatergic signaling in psychiatric illnesses, including proteins associated with receptor signaling complexes in the postsynaptic density (PSD). In particular the N-methyl-d-aspartate (NMDA) receptor complex has been associated with these illnesses. Several subcortical structures including the striatum are innervated by direct glutamatergic projections from the prefrontal cortex, and these connections may be affected in severe psychiatric illnesses. Abnormal expression of molecules critical for glutamatergic signaling in subcortical structures may thus be associated with the pathophysiology of severe psychiatric illnesses. In the present study postmortem tissue from patients with schizophrenia, bipolar disorder and major depression was used to examine striatal expression of transcripts encoding NMDA receptor interacting proteins of the PSD required for trafficking, membrane targeting and synaptic function of this receptor. We found decreased striatal expression of transcripts encoding PSD-95 and SAP-102 in bipolar disorder and of SAP-102 in major depression and schizophrenia, while no significant changes in NF--L and PSD-93 mRNAs were observed. Abnormal expression of SAP-102 in schizophrenia and SAP-102 and PSD-95 in mood disorders in subcortical structures receiving afferent glutamatergic innervation from frontal cortex suggests dysregulation of cortical-subcortical circuitry in these illnesses.
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Affiliation(s)
- Lars V Kristiansen
- Department of Psychiatry and The Molecular and Behavioral Neuroscience Institute, University of Michigan, 205 Zina Pitcher Place, Ann Arbor, MI 48109-0720, USA.
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