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Chen D, Zhao T, Ni K, Dai P, Yang L, Xu Y, Li F. Metabolic investigation on ZL006 for the discovery of a potent prodrug for the treatment of cerebral ischemia. Bioorg Med Chem Lett 2016; 26:2152-5. [DOI: 10.1016/j.bmcl.2016.03.074] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 03/04/2016] [Accepted: 03/19/2016] [Indexed: 12/11/2022]
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Sinclair D, Cesare J, McMullen M, Carlson GC, Hahn CG, Borgmann-Winter KE. Effects of sex and DTNBP1 (dysbindin) null gene mutation on the developmental GluN2B-GluN2A switch in the mouse cortex and hippocampus. J Neurodev Disord 2016; 8:14. [PMID: 27134685 PMCID: PMC4852102 DOI: 10.1186/s11689-016-9148-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 04/03/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Neurodevelopmental disorders such as autism spectrum disorders and schizophrenia differentially impact males and females and are highly heritable. The ways in which sex and genetic vulnerability influence the pathogenesis of these disorders are not clearly understood. The n-methyl-d-aspartate (NMDA) receptor pathway has been implicated in schizophrenia and autism spectrum disorders and changes dramatically across postnatal development at the level of the GluN2B-GluN2A subunit "switch" (a shift from reliance on GluN2B-containing receptors to reliance on GluN2A-containing receptors). We investigated whether sex and genetic vulnerability (specifically, null mutation of DTNBP1 [dysbindin; a possible susceptibility gene for schizophrenia]) influence the developmental GluN2B-GluN2A switch. METHODS Subcellular fractionation to enrich for postsynaptic density (PSD), together with Western blotting and kinase assay, were used to investigate the GluN2B-GluN2A switch in the cortex and hippocampus of male and female DTNBP1 null mutant mice and their wild-type littermates. Main effects of sex and DTNBP1 genotype, and interactions with age, were assessed using factorial ANOVA. RESULTS Sex differences in the GluN2B-GluN2A switch emerged across development at the frontal cortical synapse, in parameters related to GluN2B. Males across genotypes displayed higher GluN2B:GluN2A and GluN2B:GluN1 ratios (p < 0.05 and p < 0.01, respectively), higher GluN2B phosphorylation at Y1472 (p < 0.01), and greater abundance of PLCγ (p < 0.01) and Fyn (p = 0.055) relative to females. In contrast, effects of DTNBP1 were evident exclusively in the hippocampus. The developmental trajectory of GluN2B was disrupted in DTNBP1 null mice (genotype × age interaction p < 0.05), which also displayed an increased synaptic GluN2A:GluN1 ratio (p < 0.05) and decreased PLCγ (p < 0.05) and Fyn (only in females; p < 0.0005) compared to wild-types. CONCLUSIONS Sex and DTNBP1 mutation influence the GluN2B-GluN2A switch at the synapse in a brain-region-specific fashion involving pY1472-GluN2B, Fyn, and PLCγ. This highlights the possible mechanisms through which risk factors may mediate their effects on vulnerability to disorders of NMDA receptor dysfunction.
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Affiliation(s)
- Duncan Sinclair
- Department of Psychiatry, Neuropsychiatric Signaling Program, University of Pennsylvania, Philadelphia, PA USA ; Present address: Schizophrenia Research Laboratory, Neuroscience Research Australia, Randwick, New South Wales Australia
| | - Joseph Cesare
- Department of Psychiatry, Neuropsychiatric Signaling Program, University of Pennsylvania, Philadelphia, PA USA
| | | | | | - Chang-Gyu Hahn
- Department of Psychiatry, Neuropsychiatric Signaling Program, University of Pennsylvania, Philadelphia, PA USA
| | - Karin E Borgmann-Winter
- Department of Psychiatry, Neuropsychiatric Signaling Program, University of Pennsylvania, Philadelphia, PA USA ; Department of Child and Adolescent Psychiatry, Children's Hospital of Philadelphia, Philadelphia, PA USA
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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: 6] [Impact Index Per Article: 0.8] [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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Hu X, Fan Q, Hou H, Yan R. Neurological dysfunctions associated with altered BACE1-dependent Neuregulin-1 signaling. J Neurochem 2016; 136:234-49. [PMID: 26465092 PMCID: PMC4833723 DOI: 10.1111/jnc.13395] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 09/23/2015] [Accepted: 09/25/2015] [Indexed: 01/09/2023]
Abstract
Inhibition of BACE1 is being pursued as a therapeutic target to treat patients suffering from Alzheimer's disease because BACE1 is the sole β-secretase that generates β-amyloid peptide. Knowledge regarding other cellular functions of BACE1 is therefore critical for the safe use of BACE1 inhibitors in human patients. Neuregulin-1 (Nrg1) is a BACE1 substrate and BACE1 cleavage of Nrg1 is critical for signaling functions in myelination, remyelination, synaptic plasticity, normal psychiatric behaviors, and maintenance of muscle spindles. This review summarizes the most recent discoveries associated with BACE1-dependent Nrg1 signaling in these areas. This body of knowledge will help to provide guidance for preventing unwanted Nrg1-based side effects following BACE1 inhibition in humans. To initiate its signaling cascade, membrane anchored Neuregulin (Nrg), mainly type I and III β1 Nrg1 isoforms and Nrg3, requires ectodomain shedding. BACE1 is one of such indispensable sheddases to release the functional Nrg signaling fragment. The dependence of Nrg on the cleavage by BACE1 is best manifested by disrupting the critical role of Nrg in the control of axonal myelination, schizophrenic behaviors as well as the formation and maintenance of muscle spindles.
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Affiliation(s)
- Xiangyou Hu
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
| | - Qingyuan Fan
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
| | - Hailong Hou
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
| | - Riqiang Yan
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
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Ganguly P, Holland FH, Brenhouse HC. Functional Uncoupling NMDAR NR2A Subunit from PSD-95 in the Prefrontal Cortex: Effects on Behavioral Dysfunction and Parvalbumin Loss after Early-Life Stress. Neuropsychopharmacology 2015; 40:2666-75. [PMID: 25953359 PMCID: PMC4864660 DOI: 10.1038/npp.2015.134] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 03/30/2015] [Accepted: 04/13/2015] [Indexed: 11/09/2022]
Abstract
Exposure to early-life stress increases vulnerability to psychiatric disorders, including depression, schizophrenia, and anxiety. Growing evidence implicates aberrant development of the prefrontal cortex (PFC) in the effects of early-life stress, which often emerge in adolescence or young adulthood. Specifically, early-life stress in the form of maternal separation (MS) in rodents has been shown to decrease parvalbumin (PVB)-positive interneurons in the adolescent PFC; however, the mechanism underpinning behavioral dysfunction and PVB loss is not yet known. We recently reported that MS causes overexpression of the NMDA subunit NR2A in the PFC of adolescent rats. Elevated PFC NR2A is also found in developmental models of schizophrenia and is correlated with behavioral deficits, acting largely through its association with the postsynaptic protein PSD-95. In addition, adolescent maturation of PVB-positive interneurons relies on NR2A-driven NMDA activity. Therefore, it is possible that the NR2A/PSD-95 signaling complex has a role in adolescent MS effects. Here, we aimed to determine whether a discrete manipulation of PFC NR2A could prevent MS effects on PFC-controlled behaviors, including cognition, anxiety, and novelty-induced hyperlocomotion, as well as PVB loss in adolescence. We intracranially infused the NR2A-specific blocking peptide TAT2A in order to uncouple NR2A from PSD-95 in the early-adolescent PFC, without antagonizing the NMDA receptor. We demonstrated that MS rats treated with TAT2A during early adolescence were protected from MS-induced PVB loss and exhibited less anxious behavior than those infused with control peptide. These data implicate NR2A-related N-methyl-D-aspartate receptor development in adolescent behavioral and neural consequences of early-life stress.
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Affiliation(s)
- Prabarna Ganguly
- Department of Psychology, Northeastern University, Boston, MA, USA
| | | | - Heather C Brenhouse
- Department of Psychology, Northeastern University, Boston, MA, USA,Department of Psychology, Northeastern University, 125 NI, Boston, MA 02115, USA, Tel: +1 617 373 6856, Fax: +1 617 373 8714, E-mail:
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Alternative splicing modulates Kv channel clustering through a molecular ball and chain mechanism. Nat Commun 2015; 6:6488. [DOI: 10.1038/ncomms7488] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 02/02/2015] [Indexed: 01/22/2023] Open
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Ishrat T, Pillai B, Soliman S, Fouda AY, Kozak A, Johnson MH, Ergul A, Fagan SC. Low-dose candesartan enhances molecular mediators of neuroplasticity and subsequent functional recovery after ischemic stroke in rats. Mol Neurobiol 2014; 51:1542-53. [PMID: 25084762 DOI: 10.1007/s12035-014-8830-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 07/22/2014] [Indexed: 01/19/2023]
Abstract
We have previously reported that angiotensin type 1 receptor (AT1R) blockade with candesartan exerts neurovascular protection after experimental cerebral ischemia. Here, we tested the hypothesis that a low, subhypotensive dose of candesartan enhances neuroplasticity and subsequent functional recovery through enhanced neurotrophic factor expression in rats subjected to ischemia reperfusion injury. Male Wistar rats (290-300 g) underwent 90 min of middle cerebral artery occlusion (MCAO) and received candesartan (0.3 mg/kg) or saline at reperfusion and then once every 24 h for 7 days. Functional deficits were assessed in a blinded manner at 1, 3, 7, and 14 days after MCAO. Animals were sacrificed 14-day post-stroke and the brains perfused for infarct size by cresyl violet. Western blot and immunohistochemistry were used to assess the expression of growth factors and synaptic proteins. Candesartan-treated animals showed a significant reduction in the infarct size [t (13) = -5.5, P = 0.0001] accompanied by functional recovery in Bederson [F (1, 13) = 7.9, P = 0.015], beam walk [F (1, 13) = 6.7, P = 0.023], grip strength [F (1, 13) = 15.2, P = 0.0031], and rotarod performance [F (1, 14) = 29.8, P < 0.0001]. In addition, candesartan-treated animals showed significantly higher expression of active metalloproteinase-3 (MMP-3), laminin, and angiopoietin-1 (Ang-1). The expression of vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF) and its receptor was significantly increased in the animals treated with candesartan. Also, we observed significant increases in neuroplasticity markers, synaptophysin, and PSD-95. These results indicate that low-dose candesartan had a large and enduring effect on measures of plasticity, and this accompanied the functional recovery after ischemic stroke.
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58
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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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59
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Zhao C, Du CP, Peng Y, Xu Z, Sun CC, Liu Y, Hou XY. The upregulation of NR2A-containing N-methyl-D-aspartate receptor function by tyrosine phosphorylation of postsynaptic density 95 via facilitating Src/proline-rich tyrosine kinase 2 activation. Mol Neurobiol 2014; 51:500-11. [PMID: 24981431 DOI: 10.1007/s12035-014-8796-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 06/15/2014] [Indexed: 10/25/2022]
Abstract
The activation of postsynaptic N-methyl-D-aspartate (NMDA) receptors is required for long-term potentiation (LTP) of synaptic transmission. Postsynaptic density 95 (PSD-95) serves as a scaffold protein that tethers NMDA receptor subunits, kinases, and signal molecules. Our previous study proves that PSD-95 is a substrate of Src/Fyn and identifies Y523 on PSD-95 as a principal phosphorylation site. In this paper, we try to define an involvement and molecular consequences of PSD-95 phosphorylation by Src in NMDA receptor regulation. We found that either NMDA or chemical LTP induction leads to rapid phosphorylation of PSD-95 by Src in cultured cortical neurons. The phosphorylation of Y523 on PSD-95 potentiates NR2A-containing NMDA receptor current amplitude, implying an important role of Src-mediated PSD-95 phosphorylation in NMDA receptor activation. Comparing to wild-type PSD-95, overexpression of nonphosphorylatable mutant PSD-95Y523F attenuated the NMDA-stimulated NR2A tyrosine phosphorylation that enhances electrophysiological responses of NMDA receptor channels, while did not affect the membrane localization of NR2A subunits. PSD-95Y523D, a phosphomimetic mutant of PSD-95, induced NR2A tyrosine phosphorylation even if there was no NMDA treatment. In addition, the deficiency of Y523 phosphorylation on PSD-95 impaired the facilitatory effect of PSD-95 on the activation of Src and proline-rich tyrosine kinase 2 (Pyk2) and decreased the binding of Pyk2 with PSD-95. These results indicate that PSD-95 phosphorylation by Src facilitates the integration of Pyk2 to PSD-95 signal complex, the activation of Pyk2/Src, as well as the subsequent tyrosine phosphorylation of NR2A, which ultimately results in the upregulation of NMDA receptor function and synaptic transmission.
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Affiliation(s)
- Chao Zhao
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, 209 Tongshan Road, Xuzhou, Jiangsu, 221004, China
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Abstract
LMTK3 belongs to the LMTK family of protein kinases that are predominantly expressed in the brain. Physiological functions of LMTK3 and other members of the LMTK family in the CNS remain unknown. In this study, we performed a battery of behavioral analyses using Lmtk3(-/-) mice and showed that these mice exhibit abnormal behaviors, including pronounced locomotor hyperactivity, reduced anxiety behavior, and decreased depression-like behavior. Concurrently, the dopamine metabolite levels and dopamine turnover rate are increased in the striata of Lmtk3(-/-) mice compared with wild-type controls. In addition, using cultured primary neurons from Lmtk3(-/-) mice, we found that LMTK3 is involved in the endocytic trafficking of N-methyl-d-aspartate receptors, a type of ionotropic glutamate receptor. Altered membrane traffic of the receptor in Lmtk3(-/-) neurons may underlie behavioral abnormalities in the mutant animals. Together, our data suggest that LMTK3 plays an important role in regulating locomotor behavior in mice.
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Phosphorylation of Ser1166 on GluN2B by PKA is critical to synaptic NMDA receptor function and Ca2+ signaling in spines. J Neurosci 2014; 34:869-79. [PMID: 24431445 DOI: 10.1523/jneurosci.4538-13.2014] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The NMDA-type glutamate receptor (NMDAR) is essential for synaptogenesis, synaptic plasticity, and higher cognitive function. Emerging evidence indicates that NMDAR Ca(2+) permeability is under the control of cAMP/protein kinase A (PKA) signaling. Whereas the functional impact of PKA on NMDAR-dependent Ca(2+) signaling is well established, the molecular target remains unknown. Here we identify serine residue 1166 (Ser1166) in the carboxy-terminal tail of the NMDAR subunit GluN2B to be a direct molecular and functional target of PKA phosphorylation critical to NMDAR-dependent Ca(2+) permeation and Ca(2+) signaling in spines. Activation of β-adrenergic and D1/D5-dopamine receptors induces Ser1166 phosphorylation. Loss of this single phosphorylation site abolishes PKA-dependent potentiation of NMDAR Ca(2+) permeation, synaptic currents, and Ca(2+) rises in dendritic spines. We further show that adverse experience in the form of forced swim, but not exposure to fox urine, elicits striking phosphorylation of Ser1166 in vivo, indicating differential impact of different forms of stress. Our data identify a novel molecular and functional target of PKA essential to NMDAR-mediated Ca(2+) signaling at synapses and regulated by the emotional response to stress.
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Ting JH, Marks DR, Schleidt SS, Wu JN, Zyskind JW, Lindl KA, Blendy JA, Pierce RC, Jordan-Sciutto KL. Targeted gene mutation of E2F1 evokes age-dependent synaptic disruption and behavioral deficits. J Neurochem 2014; 129:850-63. [PMID: 24460902 DOI: 10.1111/jnc.12655] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 11/21/2013] [Accepted: 01/10/2014] [Indexed: 02/05/2023]
Abstract
Aberrant expression and activation of the cell cycle protein E2F1 in neurons has been implicated in many neurodegenerative diseases. As a transcription factor regulating G1 to S phase progression in proliferative cells, E2F1 is often up-regulated and activated in models of neuronal death. However, despite its well-studied functions in neuronal death, little is known regarding the role of E2F1 in the mature brain. In this study, we used a combined approach to study the effect of E2F1 gene disruption on mouse behavior and brain biochemistry. We identified significant age-dependent olfactory and memory-related deficits in E2f1 mutant mice. In addition, we found that E2F1 exhibits punctated staining and localizes closely to the synapse. Furthermore, we found a mirroring age-dependent loss of post-synaptic protein-95 in the hippocampus and olfactory bulb as well as a global loss of several other synaptic proteins. Coincidently, E2F1 expression is significantly elevated at the ages, in which behavioral and synaptic perturbations were observed. Finally, we show that deficits in adult neurogenesis persist late in aged E2f1 mutant mice which may partially contribute to the behavior phenotypes. Taken together, our data suggest that the disruption of E2F1 function leads to specific age-dependent behavioral deficits and synaptic perturbations. E2F1 is a transcription factor regulating cell cycle progression and apoptosis. Although E2F1 dysregulation under toxic conditions can lead to neuronal death, little is known about its physiologic activity in the healthy brain. Here, we report significant age-dependent olfactory and memory deficits in mice with dysfunctional E2F1. Coincident with these behavioral changes, we also found age-matched synaptic disruption and persisting reduction in adult neurogenesis. Our study demonstrates that E2F1 contributes to physiologic brain structure and function.
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Affiliation(s)
- Jenhao H Ting
- Department of Pathology, University of Pennsylvania, School of Dental Medicine, Philadelphia, Pennsylvania, USA
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63
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Srivastava DP, Evans PD. G-protein oestrogen receptor 1: trials and tribulations of a membrane oestrogen receptor. J Neuroendocrinol 2013; 25:1219-30. [PMID: 23822769 DOI: 10.1111/jne.12071] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 06/20/2013] [Accepted: 06/29/2013] [Indexed: 11/29/2022]
Abstract
Oestrogens are now recognised to be able to initiate rapid, fast responses, in addition to their classical, longer-term actions. There is a growing appreciation of the potential implications of this mode of action for oestrogenic signalling in both neuronal and non-neuronal systems. As such, much effort has been made to determine the mechanisms that are critical for transducing these rapid effects into cellular responses. Recently, an orphan G-protein-coupled receptor (GPCR), termed GPR30, was identified as an oestrogen-sensitive receptor in cancer cells. This receptor, now term G-protein oestrogen receptor 1 (GPER1) has been the subject of many investigations, and a role for this receptor in the nervous system is now emerging. In this review, we highlight some of the more recent advances in our understanding of the distribution and subcellular localisation of this receptor in the brain, as well as some of the evidence for the potential role that this receptor may play in the brain. We then discuss some of the controversies surrounding the pharmacology of this receptor, and attempt to reconcile these by suggesting that the 'agonist-specific coupling' model of GPCR function may provide a potential explanation for some of the divergent reports of GPER1 pharmacology.
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Affiliation(s)
- D P Srivastava
- Department of Neuroscience & Centre for the Cellular Basis of Behaviour, The James Black Centre, Institute of Psychiatry, King's College London, London, UK
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Yun Y, Yao G, Yue H, Guo L, Qin G, Li G, Sang N. SO(2) inhalation causes synaptic injury in rat hippocampus via its derivatives in vivo. CHEMOSPHERE 2013; 93:2426-2432. [PMID: 24099899 DOI: 10.1016/j.chemosphere.2013.08.063] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 08/14/2013] [Accepted: 08/16/2013] [Indexed: 06/02/2023]
Abstract
SO(2) remains a common air pollutant, almost half of the world's population uses coal and biomass fuels for domestic energy. Limited evidence suggests that exposure to SO(2) may be associated with neurotoxicity and increased risk of hospitalization and mortality of many brain disorders. However, our understanding of the mechanisms by which SO(2) causes harmful insults on neurons remains elusive. To explore the molecular mechanism of SO(2)-induced neurotoxic effects in hippocampal neurons, we evaluated the synaptic plasticity in rat hippocampus after exposure to SO(2)at various concentrations (3.5 and 7 mg m(-3), 6 h d(-1), for 90 d) in vivo, and in primary cultured hippocampal neurons (DIV7 and DIV14) after the treatment of SO2 derivatives in vitro. The results showed that SYP, PSD-95, NR-2B, p-ERK1/2 and p-CREB were consistently inhibited by SO(2)/SO(2) derivatives in more mature hippocampal neurons in vivo and in vitro, while the effects were opposite in young hippocampal neurons. Our results indicated that in young neurons, SO(2) exposure produced neuronal insult is similar to ischemic injury; while in more mature neurons, SO(2) exposure induced synaptic dysfunctions might participate in cognitive impairment. The results implied that SO(2) inhalation could cause different neuronal injury during brain development, and suggested that the molecular mechanisms might be involved in the changes of synaptic plasticity.
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Affiliation(s)
- Yang Yun
- College of Environment and Resource, Shanxi University, Taiyuan, Shanxi 030006, PR China
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Population-specific haplotype association of the postsynaptic density gene DLG4 with schizophrenia, in family-based association studies. PLoS One 2013; 8:e70302. [PMID: 23936182 PMCID: PMC3723755 DOI: 10.1371/journal.pone.0070302] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 06/16/2013] [Indexed: 12/04/2022] Open
Abstract
The post-synaptic density (PSD) of glutamatergic synapses harbors a multitude of proteins critical for maintaining synaptic dynamics. Alteration of protein expression levels in this matrix is a marked phenomenon of neuropsychiatric disorders including schizophrenia, where cognitive functions are impaired. To investigate the genetic relationship of genes expressed in the PSD with schizophrenia, a family-based association analysis of genetic variants in PSD genes such as DLG4, DLG1, PICK1 and MDM2, was performed, using Japanese samples (124 pedigrees, n = 376 subjects). Results showed a significant association of the rs17203281 variant from the DLG4 gene, with preferential transmission of the C allele (p = 0.02), although significance disappeared after correction for multiple testing. Replication analysis of this variant, found no association in a Chinese schizophrenia cohort (293 pedigrees, n = 1163 subjects) or in a Japanese case-control sample (n = 4182 subjects). The DLG4 expression levels between postmortem brain samples from schizophrenia patients showed no significant changes from controls. Interestingly, a five marker haplotype in DLG4, involving rs2242449, rs17203281, rs390200, rs222853 and rs222837, was enriched in a population specific manner, where the sequences A-C-C-C-A and G-C-C-C-A accumulated in Japanese (p = 0.0009) and Chinese (p = 0.0007) schizophrenia pedigree samples, respectively. However, this could not be replicated in case-control samples. None of the variants in other examined candidate genes showed any significant association in these samples. The current study highlights a putative role for DLG4 in schizophrenia pathogenesis, evidenced by haplotype association, and warrants further dense screening for variants within these haplotypes.
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Geng D, Kang L, Su Y, Jia J, Ma J, Li S, Du J, Cui H. Protective effects of EphB2 on Aβ1-42 oligomer-induced neurotoxicity and synaptic NMDA receptor signaling in hippocampal neurons. Neurochem Int 2013; 63:283-90. [PMID: 23831214 DOI: 10.1016/j.neuint.2013.06.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 06/14/2013] [Accepted: 06/15/2013] [Indexed: 12/19/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized pathologically by the abnormal deposition of extracellular amyloid-β (Aβ) oligomers. However, the nature and precise mechanism of the toxicity of Aβ oligomers are not clearly understood. Aβ oligomers have been previously shown to cause a major loss of EphB2, a member of the EphB family of receptor tyrosine kinases. To determine the effect of EphB2 on Aβ oligomer-induced neurotoxicity and the underlying molecular mechanisms, we examined the EphB2 gene in cultured hippocampal neurons. Using a cellular model of AD, Aβ1-42 oligomers were confirmed to induce neurotoxicity in a time-dependent manner and result in a major decrease of EphB2. EphB2 overexpression could prevent the neurotoxicity of hippocampal neurons from exposure to Aβ1-42 oligomers for 1h. Further analysis revealed that EphB2 overexpression increased synaptic NR1 and NR2B expression in Aβ1-42 oligomer-treated neurons. Moreover, EphB2 overexpression prevented Aβ1-42 oligomer-induced downregulation of dephosphorylated p38 MAPK and phosphorylated CREB. Together, these results suggest that EphB2 is a factor which protects hippocampal neurons against the toxicity of Aβ1-42 oligomers, and we infer that the protection of EphB2 is achieved by increasing the synaptic NMDA receptor level and downstream p38 MAPK and CREB signaling in hippocampal neurons. This study provides new molecular insights into the neuroprotective effect of EphB2 and highlights its potential therapeutic role in the management of AD.
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Affiliation(s)
- Dandan Geng
- Department of Human Anatomy, Hebei Medical University, Shijiazhuang 050017, Hebei, PR China
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67
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Yang S, Roselli F, Patchev AV, Yu S, Almeida OFX. Non-receptor-tyrosine kinases integrate fast glucocorticoid signaling in hippocampal neurons. J Biol Chem 2013; 288:23725-39. [PMID: 23818519 DOI: 10.1074/jbc.m113.470146] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Despite numerous descriptions of rapid effects of corticosterone on neuronal function, the intracellular mechanisms responsible for these changes remain elusive. The present comprehensive analysis reveals that signaling from a membrane-located G protein-coupled receptor activates PKC, Akt/PKB, and PKA, which subsequently trigger the phosphorylation of the tyrosine kinases Pyk2, Src, and Abl. These changes induce rapid cytoskeletal rearrangements (increased PSD-95 co-clustering) within the post-synaptic density; these events are accompanied by increased surface NMDA receptor expression, reflecting corticosterone-induced inhibition of NMDA receptor endocytosis. Notably, none of these signaling mechanisms require de novo protein synthesis. The observed up-regulation of ERK1/2 (downstream of NMDA receptor signaling) together with the fact that c-Abl integrates cytoplasmic and nuclear functions introduces a potential mechanism through which rapid signaling initiated at the plasma membrane may eventually determine the long term integrated response to corticosterone by impacting on the transcriptional machinery that is regulated by classical, nuclear mineralocorticoid, and glucocorticoid receptors.
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Affiliation(s)
- Silei Yang
- Max Planck Institute of Psychiatry, 80804 Munich, Germany
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68
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Cousins SL, Innocent N, Stephenson FA. Neto1 associates with the NMDA receptor/amyloid precursor protein complex. J Neurochem 2013; 126:554-64. [PMID: 23621516 DOI: 10.1111/jnc.12280] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 03/20/2013] [Accepted: 04/14/2013] [Indexed: 11/30/2022]
Abstract
Neuropilin tolloid-like 1 (Neto1), is a CUB domain-containing transmembrane protein that was recently identified as a novel component of the NMDA receptor complex. Here, we have investigated the possible association of Neto1 with the amyloid precursor protein (APP)695/GluN1/GluN2A and APP695/GluN1/GluN2B NMDA receptor trafficking complexes that we have previously identified. Neto1(HA) was shown to co-immunoprecipitate with assembled NMDA receptors via GluN2A or GluN2B subunits; Neto1(HA) did not co-immunoprecipitate APP695(FLAG) . Co-immunoprecipitations from mammalian cells co-transfected with APP695(FLAG) , Neto1(HA) and GluN1/GluN2A or GluN1/GluN2B revealed that all four proteins co-exist within one macromolecular complex. Immunoprecipitations from native brain tissue similarly revealed the existence of a GluN1/GluN2A or GluN2B/APP/Neto1 complex. Neto1(HA) caused a reduction in the surface expression of both NMDA receptor subtypes, but had no effect on APP695(FLAG) - or PSD-95α(c-Myc) enhanced surface receptor expression. The Neto1 binding domain of GluN2A was mapped using GluN1/GluN2A chimeras and GluN2A truncation constructs. The extracellular GluN2A domain does not contribute to association with Neto1(HA) but deletion of the intracellular tail resulted in a loss of Neto-1(HA) co-immunoprecipitation which was paralleled by a loss of association between GluN2A and SAP102. Thus, Neto1 is concluded to be a component of APP/NMDA receptor trafficking complexes.
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69
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Bai N, Hayashi H, Aida T, Namekata K, Harada T, Mishina M, Tanaka K. Dock3 interaction with a glutamate-receptor NR2D subunit protects neurons from excitotoxicity. Mol Brain 2013; 6:22. [PMID: 23641686 PMCID: PMC3652797 DOI: 10.1186/1756-6606-6-22] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 03/28/2013] [Indexed: 11/25/2022] Open
Abstract
Background N-methyl-D-aspartate receptors (NMDARs) are critical for neuronal development and synaptic plasticity. Dysregulation of NMDARs is implicated in neuropsychiatric disorders. Native NMDARs are heteromultimeric protein complexes consisting of NR1 and NR2 subunits. NR2 subunits (NR2A–D) are the major determinants of the functional properties of NMDARs. Most research has focused on NR2A- and/or NR2B-containing receptors. A recent study demonstrated that NR2C- and/or NR2D-containing NMDARs are the primary targets of memantine, a drug that is widely prescribed to treat Alzheimer’s disease. Our laboratory demonstrated that memantine prevents the loss of retinal ganglion cells (RGCs) in GLAST glutamate transporter knockout mice, a model of normal tension glaucoma (NTG), suggesting that NR2D-containing receptors may be involved in RGC loss in NTG. Results Here we demonstrate that NR2D deficiency attenuates RGC loss in GLAST-deficient mice. Furthermore, Dock3, a guanine nucleotide exchange factor, binds to the NR2D C-terminal domain and reduces the surface expression of NR2D, thereby protecting RGCs from excitotoxicity. Conclusions These results suggest that NR2D is involved in the degeneration of RGCs induced by excitotoxicity, and that the interaction between NR2D and Dock3 may have a neuroprotective effect. These findings raise the possibility that NR2D and Dock3 might be potential therapeutic targets for treating neurodegenerative diseases such as Alzheimer’s disease and NTG.
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Affiliation(s)
- Ning Bai
- Laboratory of Molecular Neuroscience, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
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Snyder MA, Gao WJ. NMDA hypofunction as a convergence point for progression and symptoms of schizophrenia. Front Cell Neurosci 2013; 7:31. [PMID: 23543703 PMCID: PMC3608949 DOI: 10.3389/fncel.2013.00031] [Citation(s) in RCA: 163] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 03/11/2013] [Indexed: 01/05/2023] Open
Abstract
Schizophrenia is a disabling mental illness that is now recognized as a neurodevelopmental disorder. It is likely that genetic risk factors interact with environmental perturbations to affect normal brain development and that this altered trajectory results in a combination of positive, negative, and cognitive symptoms. Although the exact pathophysiology of schizophrenia is unknown, the N-methyl-D-aspartate receptor (NMDAR), a major glutamate receptor subtype, has received great attention. Proper expression and regulation of NMDARs in the brain is critical for learning and memory processes as well as cortical plasticity and maturation. Evidence from both animal models and human studies implicates a dysfunction of NMDARs both in disease progression and symptoms of schizophrenia. Furthermore, mutations in many of the known genetic risk factors for schizophrenia suggest that NMDAR hypofunction is a convergence point for schizophrenia. In this review, we discuss how disrupted NMDAR function leads to altered neurodevelopment that may contribute to the progression and development of symptoms for schizophrenia, particularly cognitive deficits. We review the shared signaling pathways among the schizophrenia susceptibility genes DISC1, neuregulin1, and dysbindin, focusing on the AKT/GSK3β pathway, and how their mutations and interactions can lead to NMDAR dysfunction during development. Additionally, we explore what open questions remain and suggest where schizophrenia research needs to move in order to provide mechanistic insight into the cause of NMDAR dysfunction, as well as generate possible new avenues for therapeutic intervention.
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Affiliation(s)
- Melissa A Snyder
- Department of Neurobiology and Anatomy, Drexel University College of Medicine Philadelphia, PA, USA
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71
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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: 146] [Impact Index Per Article: 13.3] [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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Maki BA, Aman TK, Amico-Ruvio SA, Kussius CL, Popescu GK. C-terminal domains of N-methyl-D-aspartic acid receptor modulate unitary channel conductance and gating. J Biol Chem 2012; 287:36071-80. [PMID: 22948148 PMCID: PMC3476275 DOI: 10.1074/jbc.m112.390013] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 08/11/2012] [Indexed: 11/06/2022] Open
Abstract
NMDA receptors (NRs) are glutamate-gated calcium-permeable channels that are essential for normal synaptic transmssion and contribute to neurodegeneration. Tetrameric proteins consist of two obligatory GluN1 (N1) and two GluN2 (N2) subunits, of which GluN2A (2A) and GluN2B (2B) are prevalent in adult brain. The intracellularly located C-terminal domains (CTDs) make a significant portion of mass of the receptors and are essential for plasticity and excitotoxicity, but their functions are incompletely defined. Recent evidence shows that truncation of the N2 CTD alters channel kinetics; however, the mechanism by which this occurs is unclear. Here we recorded activity from individual NRs lacking the CTDs of N1, 2A, or 2B and determined the gating mechanisms of these receptors. Receptors lacking the N1 CTDs had larger unitary conductance and faster deactivation kinetics, receptors lacking the 2A or 2B CTDs had longer openings and longer desensitized intervals, and the first 100 amino acids of the N2 CTD were essential for these changes. In addition, receptors lacking the CTDs of either 2A or 2B maintained isoform-specific kinetic differences and swapping CTDs between 2A and 2B had no effect on single-channel properties. Based on these results, we suggest that perturbations in the CTD can modify the NR-mediated signal in a subunit-dependent manner, in 2A these effects are most likely mediated by membrane-proximal residues, and the isoform-specific biophysical properties conferred by 2A and 2B are CTD-independent. The kinetic mechanisms we developed afford a quantitative approach to understanding how the intracellular domains of NR subunits can modulate the responses of the receptor.
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Affiliation(s)
| | - Teresa K. Aman
- the Department of Biochemistry, University at Buffalo, State University of New York, Buffalo, New York 14214
| | - Stacy A. Amico-Ruvio
- the Department of Biochemistry, University at Buffalo, State University of New York, Buffalo, New York 14214
| | - Cassandra L. Kussius
- the Department of Biochemistry, University at Buffalo, State University of New York, Buffalo, New York 14214
| | - Gabriela K. Popescu
- From the Neuroscience Program and
- the Department of Biochemistry, University at Buffalo, State University of New York, Buffalo, New York 14214
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Pereda AE, Curti S, Hoge G, Cachope R, Flores CE, Rash JE. Gap junction-mediated electrical transmission: regulatory mechanisms and plasticity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:134-46. [PMID: 22659675 DOI: 10.1016/j.bbamem.2012.05.026] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 05/16/2012] [Accepted: 05/23/2012] [Indexed: 02/08/2023]
Abstract
The term synapse applies to cellular specializations that articulate the processing of information within neural circuits by providing a mechanism for the transfer of information between two different neurons. There are two main modalities of synaptic transmission: chemical and electrical. While most efforts have been dedicated to the understanding of the properties and modifiability of chemical transmission, less is still known regarding the plastic properties of electrical synapses, whose structural correlate is the gap junction. A wealth of data indicates that, rather than passive intercellular channels, electrical synapses are more dynamic and modifiable than was generally perceived. This article will discuss the factors determining the strength of electrical transmission and review current evidence demonstrating its dynamic properties. Like their chemical counterparts, electrical synapses can also be plastic and modifiable. This article is part of a Special Issue entitled: The Communicating junctions, roles and dysfunctions.
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Affiliation(s)
- Alberto E Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA.
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74
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Vance KM, Hansen KB, Traynelis SF. GluN1 splice variant control of GluN1/GluN2D NMDA receptors. J Physiol 2012; 590:3857-75. [PMID: 22641781 DOI: 10.1113/jphysiol.2012.234062] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
NMDA receptors are ionotropic glutamate receptors that mediate a slow, Ca2+-permeable component of excitatory synaptic transmission in the central nervous system. Recombinant GluN1-1a/GluN2D receptors are characterized by low channel open probability and prolonged deactivation time course following the removal of agonist. Here, we show that the deactivation time course, agonist potency, and single channel properties of GluN2D-containing NMDA receptors are modulated by alternative RNA splicing of GluN1. Our results demonstrate that GluN1 exon 5, which encodes a 21-amino-acid insert in the amino-terminal domain, is a key determinant of GluN1/GluN2D receptor function. GluN1-1b/GluN2D receptors, which contain the residues encoded by exon 5, deactivate with a dual exponential time course described by a τFAST of 410 ms and a τSLOW of 1100 ms. This time course is 3-fold more rapid than that for exon 5-lacking GluN1-1a/GluN2D, which deactivates with a τFAST of 1100 ms and a τSLOW of 3400 ms. Exon 5-containing NMDA receptors also have a two-fold higher open probability (0.037) than exon 5-lacking receptors (0.017). Furthermore, inclusion of exon 5-encoded residues within the GluN1-1b subunit decreases the potency for the endogenous agonist l-glutamate. Evaluation of receptor kinetics for NMDA receptors containing mutated GluN1-1b subunits and wild-type GluN2D identified residue Lys211 in GluN1-1b as a key determinant of exon 5 control of the deactivation time course and glutamate potency. Evaluation of a kinetic model of GluN1/GluN2D gating suggests that residues encoded by exon 5 influence several rate-limiting steps. These data demonstrate that the GluN1 subunit is a key determinant of the kinetic and pharmacological properties of GluN2D-containing NMDA receptors.
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Affiliation(s)
- Katie M Vance
- S. F. Traynelis: Department of Pharmacology, Rollins Research Center, 1510 Clifton Road, Atlanta, GA 30322-3090, USA
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75
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Knock-down of postsynaptic density protein 95 expression by antisense oligonucleotides protects against apoptosis-like cell death induced by oxygen-glucose deprivation in vitro. Neurosci Bull 2012; 28:69-76. [PMID: 22233891 DOI: 10.1007/s12264-012-1065-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
Abstract
OBJECTIVE Postsynaptic density protein 95 (PSD-95) plays important roles in the regulation of glutamate signaling, such as that of N-methyl-D-aspartate receptors (NMDARs). In this study, the functional roles of PSD-95 in tyrosine phosphorylation of NMDAR subunit 2A (NR2A) and in apoptosis-like cell death induced by oxygen-glucose deprivation (OGD) in cultured rat cortical neurons were investigated. METHODS We used immunoprecipitation and immunoblotting to detect PSD-95 protein level, tyrosine phosphorylation level of NR2A, and the interaction between PSD-95 and NR2A or Src. Apoptosis-like cells were observed by 4,6-diamidino-2-phenylindole staining. RESULTS Tyrosine phosphorylation of NR2A and apoptosis-like cell death were increased after recovery following 60-min OGD. The increases were attenuated by pretreatment with antisense oligonucleotides against PSD-95 before OGD, but not by missense oligonucleotides or vehicle. PSD-95 antisense oligonucleotides also inhibited the increased interaction between PSD-95 and NR2A or Src, while NR2A expression did not change under this condition. CONCLUSION PSD-95 may be involved in regulating NR2A tyrosine phosphorylation by Src kinase. Inhibition of PSD-95 expression can be neuroprotective against apoptosis-like cell death after recovery from OGD.
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76
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Ling W, Chang L, Song Y, Lu T, Jiang Y, Li Y, Wu Y. Immunolocalization of NR1, NR2A, and PSD-95 in rat hippocampal subregions during postnatal development. Acta Histochem 2012; 114:285-95. [PMID: 21719075 DOI: 10.1016/j.acthis.2011.06.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 06/01/2011] [Accepted: 06/01/2011] [Indexed: 01/14/2023]
Abstract
Although the expression of NMDARs and synaptic-associated proteins has been widely studied, the temporospatial distribution of NMDAR subunits and synaptic proteins in different hippocampal subregions during postnatal development still lacks detailed information, and the relationship between NR1 or NR2 subunits and PSD-95 family proteins is controversial. In this study, we used immunofluorescent staining to assess NR1 or NR2A and PSD-95 expressions and the relationship between them in CA1, CA3, and DG of rat hippocampus on postnatal (P) days: P0, P4, P7, P10, P14, P21, P28, P56. The results showed that from P0 to P56, NR1, NR2A, and PSD-95 expressions increased gradually, and the time points of their expression peak differed in CA1, CA3, and DG during postnatal development. Interestingly, although the expression of PSD-95 was positively correlated to both NR1 and NR2A, the NR1 and PSD-95 coexpressed puncta were greatest in CA3, while NR2A and PSD-95 coexpressed puncta were greatest in CA1, compared to other subregions. Surprisingly, at P21, among different strata of CA1, the area of highest expression of NR2A was dramatically changed from stratum pyramidale to stratum polymorphum and stratum moleculare, and returned to stratum pyramidale gradually on the later observed days again, indicating that P21 may be one critical timepoint during postnatal development in CA1. The specific temporospatial distribution pattern of NR1, NR2A, and PSD-95 might be related to the different physiological functions during postnatal development. Discovering the alteration of the relationship between PSD-95 and NMDAR subunits expression may be helpful for understanding mechanisms and therapy of neurodegenerative diseases.
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Affiliation(s)
- Wei Ling
- Department of Anatomy, Capital Medical University, Beijing, China
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77
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Huang YN, Tsai RY, Lin SL, Chien CC, Cherng CH, Wu CT, Yeh CC, Wong CS. Amitriptyline attenuates astrocyte activation and morphine tolerance in rats: Role of the PSD-95/NR1/nNOS/PKCγ signaling pathway. Behav Brain Res 2012; 229:401-11. [DOI: 10.1016/j.bbr.2012.01.044] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 01/19/2012] [Accepted: 01/23/2012] [Indexed: 12/13/2022]
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78
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Gu Z, Liu W, Wei J, Yan Z. Regulation of N-methyl-D-aspartic acid (NMDA) receptors by metabotropic glutamate receptor 7. J Biol Chem 2012; 287:10265-10275. [PMID: 22287544 DOI: 10.1074/jbc.m111.325175] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Emerging evidence suggests that metabotropic glutamate receptors (mGluRs) are potential novel targets for brain disorders associated with the dysfunction of prefrontal cortex (PFC), a region critical for cognitive and emotional processes. Because N-methyl-D-aspartic acid receptor (NMDAR) dysregulation has been strongly associated with the pathophysiology of mental illnesses, we examined the possibility that mGluRs might be involved in modulating PFC functions by targeting postsynaptic NMDARs. We found that application of prototypical group III mGluR agonists significantly reduced NMDAR-mediated synaptic and ionic currents in PFC pyramidal neurons, which was mediated by mGluR7 localized at postsynaptic neurons and involved the β-arrestin/ERK signaling pathway. The mGluR7 modulation of NMDAR currents was prevented by agents perturbing actin dynamics and by the inhibitor of cofilin, a major actin-depolymerizing factor. Consistently, biochemical and immunocytochemical results demonstrated that mGluR7 activation increased cofilin activity and F-actin depolymerization via an ERK-dependent mechanism. Furthermore, mGluR7 reduced the association of NMDARs with the scaffolding protein PSD-95 and the surface level of NMDARs in an actin-dependent manner. These data suggest that mGluR7, by affecting the cofilin/actin signaling, regulates NMDAR trafficking and function. Because ablation of mGluR7 leads to a variety of behavioral symptoms related to PFC dysfunction, such as impaired working memory and reduced anxiety and depression, our results provide a potential mechanism for understanding the role of mGluR7 in mental health and disorders.
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Affiliation(s)
- Zhenglin Gu
- Department of Physiology and Biophysics, School of Medicine and Biomedical Sciences, State University of New York, Buffalo, New York 14214
| | - Wenhua Liu
- Department of Physiology and Biophysics, School of Medicine and Biomedical Sciences, State University of New York, Buffalo, New York 14214
| | - Jing Wei
- Department of Physiology and Biophysics, School of Medicine and Biomedical Sciences, State University of New York, Buffalo, New York 14214
| | - Zhen Yan
- Department of Physiology and Biophysics, School of Medicine and Biomedical Sciences, State University of New York, Buffalo, New York 14214.
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Zhang X, Liu X, Wang D, Liu H, Hao W. Conditioned place preference associated with level of palmitoylation of PSD-95 in rat hippocampus and nucleus accumbens. Neuropsychobiology 2012; 64:211-8. [PMID: 21912189 DOI: 10.1159/000327603] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Accepted: 03/14/2011] [Indexed: 11/19/2022]
Abstract
Psychostimulant-mediated synaptic plasticity in the hippocampus and nucleus accumbens is one of the pathological features of addiction, a disease of learning and memory. Dynamic palmitoylation of PSD-95 modulates synaptic plasticity, but its role in addiction is not fully understood. Using a morphine-conditioned place preference (CPP) rat model and Acyl-biotin exchange (ABE) labeling we found a correlation between CPP and levels of palmitoylated PSD-95 in the hippocampus and nucleus accumbens. Rats that developed significant CPP had higher levels of palmitoylation of PSD-95 in the hippocampus and nucleus accumbens. Furthermore, palmitoylation of PSD-95 was significantly decreased in the hippocampus but increased in the nucleus accumbens during the beginning of withdrawal. With long-term withdrawal, palmitoylated PSD-95 in these regions recovered, while CPP waned and physical signs gradually disappeared. However, morphine reinjection restored strong CPP without producing any significant changes in palmitoylation of PSD-95. Our findings suggest that CPP is correlated with the dynamics of PSD-95 palmitoylation in rat hippocampus and nucleus accumbens, and could be one of the mechanisms for morphine-dependent synaptic plasticity.
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Affiliation(s)
- Xiaojie Zhang
- Mental Health Institute and WHO Collaborating Center for Psychosocial Factors, Drug Abuse and Health, Second Xiangya Hospital, Central South University, Changsha, PR China
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Moutin E, Raynaud F, Fagni L, Perroy J. GKAP-DLC2 interaction organizes postsynaptic scaffold complex to enhance synaptic NMDA receptor activity. J Cell Sci 2012; 125:2030-40. [DOI: 10.1242/jcs.098160] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
At glutamatergic brain synapses, scaffolding proteins regulate receptor location and function. The targeting and organization of scaffolding proteins in the postsynaptic density (PSD) is poorly understood. A core protein of the glutamatergic receptor postsynaptic scaffold complex, GKAP, interacts with DLC2, a protein associated with molecular motors. In the present study, we combined BRET imaging, immuno-staining and electrophysiological recording to assess the role of GKAP-DLC2 interaction in the functional organization of the glutamatergic synapse. We found that GKAP-DLC2 interaction in dendritic spine stabilizes scaffolding protein expression at the PSD and enhances synaptic NMDA receptor activity. Moreover, the GKAP-DLC2 functional interaction is favored by sustained synaptic activity. These data provide a novel regulatory pathway of synaptic transmission that depends on activity-induced remodeling of the postsynaptic scaffold protein complex.
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81
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Raymond LA, André VM, Cepeda C, Gladding CM, Milnerwood AJ, Levine MS. Pathophysiology of Huntington's disease: time-dependent alterations in synaptic and receptor function. Neuroscience 2011; 198:252-73. [PMID: 21907762 PMCID: PMC3221774 DOI: 10.1016/j.neuroscience.2011.08.052] [Citation(s) in RCA: 228] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 07/31/2011] [Accepted: 08/22/2011] [Indexed: 01/27/2023]
Abstract
Huntington's disease (HD) is a progressive, fatal neurological condition caused by an expansion of CAG (glutamine) repeats in the coding region of the Huntington gene. To date, there is no cure but great strides have been made to understand pathophysiological mechanisms. In particular, genetic animal models of HD have been instrumental in elucidating the progression of behavioral and physiological alterations, which had not been possible using classic neurotoxin models. Our groups have pioneered the use of transgenic HD mice to examine the excitotoxicity hypothesis of striatal neuronal dysfunction and degeneration, as well as alterations in excitation and inhibition in striatum and cerebral cortex. In this review, we focus on synaptic and receptor alterations of striatal medium-sized spiny (MSNs) and cortical pyramidal neurons in genetic HD mouse models. We demonstrate a complex series of alterations that are region-specific and time-dependent. In particular, many changes are bidirectional depending on the degree of disease progression, that is, early vs. late, and also on the region examined. Early synaptic dysfunction is manifested by dysregulated glutamate release in striatum followed by progressive disconnection between cortex and striatum. The differential effects of altered glutamate release on MSNs originating the direct and indirect pathways is also elucidated, with the unexpected finding that cells of the direct striatal pathway are involved early in the course of the disease. In addition, we review evidence for early N-methyl-D-aspartate receptor (NMDAR) dysfunction leading to enhanced sensitivity of extrasynaptic receptors and a critical role of GluN2B subunits. Some of the alterations in late HD could be compensatory mechanisms designed to cope with early synaptic and receptor dysfunctions. The main findings indicate that HD treatments need to be designed according to the stage of disease progression and should consider regional differences.
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Affiliation(s)
- Lynn A. Raymond
- Department of Psychiatry and Brain Research Centre, University of British Columbia, Vancouver, Canada
| | - Véronique M. André
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Carlos Cepeda
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Clare M. Gladding
- Department of Psychiatry and Brain Research Centre, University of British Columbia, Vancouver, Canada
| | - Austen J. Milnerwood
- Department of Psychiatry and Brain Research Centre, University of British Columbia, Vancouver, Canada
| | - Michael S. Levine
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
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82
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Mechanisms underlying NMDA receptor synaptic/extrasynaptic distribution and function. Mol Cell Neurosci 2011; 48:308-20. [DOI: 10.1016/j.mcn.2011.05.001] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 04/20/2011] [Accepted: 05/01/2011] [Indexed: 11/23/2022] Open
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83
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Sorokina O, Sorokin A, Armstrong JD. Towards a quantitative model of the post-synaptic proteome. MOLECULAR BIOSYSTEMS 2011; 7:2813-23. [PMID: 21874189 DOI: 10.1039/c1mb05152k] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The postsynaptic compartment of the excitatory glutamatergic synapse contains hundreds of distinct polypeptides with a wide range of functions (signalling, trafficking, cell-adhesion, etc.). Structural dynamics in the post-synaptic density (PSD) are believed to underpin cognitive processes. Although functionally and morphologically diverse, PSD proteins are generally enriched with specific domains, which precisely define the mode of clustering essential for signal processing. We applied a stochastic calculus of domain binding provided by a rule-based modelling approach to formalise the highly combinatorial signalling pathway in the PSD and perform the numerical analysis of the relative distribution of protein complexes and their sizes. We specified the combinatorics of protein interactions in the PSD by rules, taking into account protein domain structure, specific domain affinity and relative protein availability. With this model we interrogated the critical conditions for the protein aggregation into large complexes and distribution of both size and composition. The presented approach extends existing qualitative protein-protein interaction maps by considering the quantitative information for stoichiometry and binding properties for the elements of the network. This results in a more realistic view of the postsynaptic proteome at the molecular level.
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Affiliation(s)
- Oksana Sorokina
- School of Informatics, University of Edinburgh, Edinburgh, UK.
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84
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Zhang H, Li W, Wang G, Su Y, Zhang C, Chen X, Xu Y, Li K. The distinct binding properties between avian/human influenza A virus NS1 and Postsynaptic density protein-95 (PSD-95), and inhibition of nitric oxide production. Virol J 2011; 8:298. [PMID: 21668967 PMCID: PMC3141680 DOI: 10.1186/1743-422x-8-298] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 06/13/2011] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The NS1 protein of influenza A virus is able to bind with many proteins that affect cellular signal transduction and protein synthesis in infected cells. The NS1 protein consists of approximately 230 amino acids and the last 4 amino acids of the NS1 C-terminal form a PDZ binding motif. Postsynaptic Density Protein-95 (PSD-95), which is mainly expressed in neurons, has 3 PDZ domains. We hypothesise that NS1 binds to PSD-95, and this binding is able to affect neuronal function. RESULT We conducted a yeast two-hybrid analysis, GST-pull down assays and co-immunoprecipitations to detect the interaction between NS1 and PSD-95. The results showed that NS1 of avian influenza virus H5N1 (A/chicken/Guangdong/1/2005) is able to bind to PSD-95, whereas NS1 of human influenza virus H1N1 (A/Shantou/169/2006) is unable to do so. The results also revealed that NS1 of H5N1 significantly reduces the production of nitric oxide (NO) in rat hippocampal neurons. CONCLUSION In summary, our study indicates that NS1 of influenza A virus can bind with neuronal PSD-95, and the avian H5N1 and human H1N1 influenza A viruses possess distinct binding properties.
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Affiliation(s)
- Heng Zhang
- Department of Microbiology & Immunology, Key Immunopathology Laboratory of Guangdong Province, Shantou University Medical College, Shantou 515041, PR China
| | - Weizhong Li
- Department of Microbiology & Immunology, Key Immunopathology Laboratory of Guangdong Province, Shantou University Medical College, Shantou 515041, PR China
| | - Gefei Wang
- Department of Microbiology & Immunology, Key Immunopathology Laboratory of Guangdong Province, Shantou University Medical College, Shantou 515041, PR China
| | - Yun Su
- Department of Microbiology & Immunology, Key Immunopathology Laboratory of Guangdong Province, Shantou University Medical College, Shantou 515041, PR China
| | - Chi Zhang
- Department of Microbiology & Immunology, Key Immunopathology Laboratory of Guangdong Province, Shantou University Medical College, Shantou 515041, PR China
| | - Xiaoxuan Chen
- Department of Microbiology & Immunology, Key Immunopathology Laboratory of Guangdong Province, Shantou University Medical College, Shantou 515041, PR China
| | - Yanxuan Xu
- Department of Microbiology & Immunology, Key Immunopathology Laboratory of Guangdong Province, Shantou University Medical College, Shantou 515041, PR China
| | - Kangsheng Li
- Department of Microbiology & Immunology, Key Immunopathology Laboratory of Guangdong Province, Shantou University Medical College, Shantou 515041, PR China
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85
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Bakkar W, Ma CL, Pabba M, Khacho P, Zhang YL, Muller E, Martina M, Bergeron R. Chronically saturating levels of endogenous glycine disrupt glutamatergic neurotransmission and enhance synaptogenesis in the CA1 region of mouse hippocampus. Synapse 2011; 65:1181-95. [PMID: 21633974 DOI: 10.1002/syn.20956] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Accepted: 05/18/2011] [Indexed: 11/08/2022]
Abstract
Glycine serves a dual role in neurotransmission. It is the primary inhibitory neurotransmitter in the spinal cord and brain stem and is also an obligatory coagonist at the excitatory glutamate, N-methyl-D-aspartate receptor (NMDAR). Therefore, the postsynaptic action of glycine should be strongly regulated to maintain a balance between its inhibitory and excitatory inputs. The glycine concentration at the synapse is tightly regulated by two types of glycine transporters, GlyT1 and GlyT2, located on nerve terminals or astrocytes. Genetic studies demonstrated that homozygous (GlyT1-/-) newborn mice display severe sensorimotor deficits characterized by lethargy, hypotonia, and hyporesponsivity to tactile stimuli and ultimately die in their first postnatal day. These symptoms are similar to those associated with the human disease glycine encephalopathy in which there is a high level of glycine in cerebrospinal fluid of affected individuals. The purpose of this investigation is to determine the impact of chronically high concentrations of endogenous glycine on glutamatergic neurotransmission during postnatal development using an in vivo mouse model (GlyT1+/-). The results of our study indicate the following; that compared with wild-type mice, CA1 pyramidal neurons from mutants display significant disruptions in hippocampal glutamatergic neurotransmission, as suggested by a faster kinetic of NMDAR excitatory postsynaptic currents, a lower reduction of the amplitude of NMDAR excitatory postsynaptic currents by ifenprodil, no difference in protein expression for NR2A and NR2B but a higher protein expression for PSD-95, an increase in their number of synapses and finally, enhanced neuronal excitability.
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Affiliation(s)
- Wafae Bakkar
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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86
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Abstract
Dynamic regulation of the localization and function of NMDA receptors (NMDARs) is critical for synaptic development and function. The composition and localization of NMDAR subunits at synapses are tightly regulated and can influence the ability of individual synapses to undergo long-lasting changes in response to stimuli. Here, we examine mechanisms by which EphB2, a receptor tyrosine kinase that binds and phosphorylates NMDARs, controls NMDAR subunit localization and function at synapses. We find that, in mature neurons, EphB2 expression levels regulate the amount of NMDARs at synapses, and EphB activation decreases Ca(2+)-dependent desensitization of NR2B-containing NMDARs. EphBs are required for enhanced localization of NR2B-containing NMDARs at synapses of mature neurons; triple EphB knock-out mice lacking EphB1-3 exhibit homeostatic upregulation of NMDAR surface expression and loss of proper targeting to synaptic sites. These findings demonstrate that, in the mature nervous system, EphBs are key regulators of the synaptic localization of NMDARs.
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87
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Geddes AE, Huang XF, Newell KA. Reciprocal signalling between NR2 subunits of the NMDA receptor and neuregulin1 and their role in schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2011; 35:896-904. [PMID: 21371516 DOI: 10.1016/j.pnpbp.2011.02.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 02/19/2011] [Accepted: 02/24/2011] [Indexed: 02/01/2023]
Abstract
Schizophrenia is a debilitating neurodevelopmental psychiatric disorder. Both the N-methyl-D-aspartate receptor (NMDAR) and neuregulin1 (NRG1) are key molecules involved in normal brain development that have been linked to schizophrenia pathology and aetiology. The NR2 proteins are critical structural and functional subunits of the NMDAR and are developmentally and spatially regulated. Altered NR2 gene and protein expression has been found in human post-mortem schizophrenia brain tissue together with changes in NRG1 and its receptor ErbB4. The NR2 subunits and ErbB4 share a common anchoring domain on the postsynaptic density and therefore a disruption to either of these molecules may influence the functioning of the other. It has been shown that NRG1 signalling can affect NMDAR levels and function, particularly phosphorylation of the NR2 subunits. However little is known about the possible effects of NMDAR dysfunction on NRG1 signalling, which is important with regards to schizophrenia aetiology as numerous risk factors for the disorder can alter NMDAR functioning during early brain development. This review focuses on the role of the NMDA receptor subunits and NRG1 signalling in schizophrenia and proposes a mechanism by which a disruption to the NMDAR, particularly via altering the balance of NR2 subunits during early development, could influence NRG1 signalling.
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Affiliation(s)
- Amy E Geddes
- Centre for Translational Neuroscience, Illawarra Health and Medical Research Institute, School of Health Sciences, University of Wollongong, Wollongong, NSW 2522, Australia
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88
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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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89
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Okvist A, Fagergren P, Whittard J, Garcia-Osta A, Drakenberg K, Horvath MC, Schmidt CJ, Keller E, Bannon MJ, Hurd YL. Dysregulated postsynaptic density and endocytic zone in the amygdala of human heroin and cocaine abusers. Biol Psychiatry 2011; 69:245-52. [PMID: 21126734 PMCID: PMC3017476 DOI: 10.1016/j.biopsych.2010.09.037] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2010] [Revised: 08/02/2010] [Accepted: 09/02/2010] [Indexed: 11/24/2022]
Abstract
BACKGROUND Glutamatergic transmission in the amygdala is hypothesized as an important mediator of stimulus-reward associations contributing to drug-seeking behavior and relapse. Insight is, however, lacking regarding the amygdala glutamatergic system in human drug abusers. METHODS We examined glutamate receptors and scaffolding proteins associated with the postsynaptic density in the human postmortem amygdala. Messenger RNA or protein levels were studied in a population of multidrug (seven heroin, eight cocaine, seven heroin/cocaine, and seven controls) or predominant heroin (29 heroin and 15 controls) subjects. RESULTS The amygdala of drug abusers was characterized by a striking positive correlation (r > .8) between α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid glutamate receptor subunit 1 (GluA1) and postsynaptic density protein-95 (PSD-95) mRNA levels, which was not evident in control subjects. Structural equation multigroup analysis of protein correlations also identified the relationship between GluA1 and PSD-95 protein levels as the distinguishing feature of abusers. In line with the GluA1-PSD-95 implications of enhanced synaptic plasticity, Homer 1b/c protein expression was increased in both heroin and cocaine users as was its binding partner, dynamin-3. Furthermore, there was a positive relationship between Homer 1b/c and dynamin-3 in drug abusers that reflected an increase in the direct physical coupling between the proteins. A noted age-related decline of Homer 1b/c-dynamin-3 interactions, as well as GluA1 levels, was blunted in abusers. CONCLUSIONS Impairment of key components of the amygdala postsynaptic density and coupling to the endocytic zone, critical for the regulation of glutamate receptor cycling, may underlie heightened synaptic plasticity in human drug abusers.
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90
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Tabatadze N, Savonenko A, Song H, Bandaru VVR, Chu M, Haughey NJ. Inhibition of neutral sphingomyelinase-2 perturbs brain sphingolipid balance and spatial memory in mice. J Neurosci Res 2010; 88:2940-51. [PMID: 20629193 DOI: 10.1002/jnr.22438] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The sphingolipid ceramide is a bioactive signaling lipid that is thought to play important roles in modulating synaptic activity, in part by regulating the function of excitatory postsynaptic receptors. However, the molecular mechanisms by which ceramide exerts its effects on synaptic activity remain largely unknown. We recently demonstrated that a rapid generation of ceramide by neutral sphingomyelinase-2 (nSMase2; also known as "sphingomyelin phosphodiesterase-3") played a key role in modulating excitatory postsynaptic currents by controlling the insertion and clustering of NMDA receptors (Wheeler et al. [2009] J. Neurochem. 109:1237-1249). We now demonstrate that nSMase2 plays a role in memory. Inhibition of nSMase2 impaired spatial and episodic-like memory in mice. At the molecular level, inhibition of nSMase2 decreased ceramide, increased PSD-95, increased the number of AMPA receptors, and altered the subunit composition of NMDA receptors. Our study identifies nSMase2 as an important component for efficient memory formation and underscores the importance of ceramide in regulating synaptic events related to learning and memory.
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Affiliation(s)
- Nino Tabatadze
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
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91
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Genetic and functional analysis of the DLG4 gene encoding the post-synaptic density protein 95 in schizophrenia. PLoS One 2010; 5:e15107. [PMID: 21151988 PMCID: PMC2996301 DOI: 10.1371/journal.pone.0015107] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 10/21/2010] [Indexed: 01/09/2023] Open
Abstract
Hypofunction of N-methyl-D-aspartate (NMDA) receptor-mediated signal transduction has been implicated in the pathophysiology of schizophrenia. Post-synaptic density protein 95 (PSD95) plays a critical role in regulating the trafficking and activity of the NMDA receptor and altered expression of the PSD95 has been detected in the post-mortem brain of patients with schizophrenia. The study aimed to examine whether the DLG4 gene that encodes the PSD95 may confer genetic susceptibility to schizophrenia. We re-sequenced the core promoter, all the exons, and 3′ untranslated regions (UTR) of the DLG4 gene in 588 Taiwanese schizophrenic patients and conducted an association study with 539 non-psychotic subjects. We did not detect any rare mutations at the protein-coding sequences of the DLG4 gene associated with schizophrenia. Nevertheless, we identified four polymorphic markers at the core promoter and 5′ UTR and one single nucleotide polymorphism (SNP) at the 3′UTR of the DLG4 gene in this sample. Genetic analysis showed an association of a haplotype (C–D) derived from 2 polymorphic markers at the core promoter (odds ratio = 1.26, 95% confidence interval = 1.06–1.51, p = 0.01), and a borderline association of the T allele of the rs13331 at 3′UTR with schizophrenia (odds ratio = 1.19, 95% confidence interval = 0.99–1.43, p = 0.06). Further reporter gene assay showed that the C-D-C-C and the T allele of the rs13331 had significant lower activity than their counter parts. Our data indicate that the expression of the DLG4 gene is subject to regulation by the polymorphic markers at the core promoter region, 5′ and 3′UTR of the gene, and is associated with the susceptibility of schizophrenia.
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92
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Distinct levels of dopamine denervation differentially alter striatal synaptic plasticity and NMDA receptor subunit composition. J Neurosci 2010; 30:14182-93. [PMID: 20962239 DOI: 10.1523/jneurosci.2149-10.2010] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
A correct interplay between dopamine (DA) and glutamate is essential for corticostriatal synaptic plasticity and motor activity. In an experimental model of Parkinson's disease (PD) obtained in rats, the complete depletion of striatal DA, mimicking advanced stages of the disease, results in the loss of both forms of striatal plasticity: long-term potentiation (LTP) and long-term depression (LTD). However, early PD stages are characterized by an incomplete reduction in striatal DA levels. The mechanism by which this incomplete reduction in DA level affects striatal synaptic plasticity and glutamatergic synapses is unknown. Here we present a model of early PD in which a partial denervation, causing mild motor deficits, selectively affects NMDA-dependent LTP but not LTD and dramatically alters NMDA receptor composition in the postsynaptic density. Our findings show that DA decrease influences corticostriatal synaptic plasticity depending on the level of depletion. The use of the TAT2A cell-permeable peptide, as an innovative therapeutic strategy in early PD, rescues physiological NMDA receptor composition, synaptic plasticity, and motor behavior.
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93
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Muscarinic receptors induce LTD of NMDAR EPSCs via a mechanism involving hippocalcin, AP2 and PSD-95. Nat Neurosci 2010; 13:1216-24. [PMID: 20852624 DOI: 10.1038/nn.2636] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Accepted: 08/13/2010] [Indexed: 02/05/2023]
Abstract
Although muscarinic acetylcholine receptors (mAChRs) and NMDA receptors (NMDARs) are important for synaptic plasticity, learning and memory, the manner in which they interact is poorly understood. We found that stimulation of muscarinic receptors, either by an agonist or by the synaptic release of acetylcholine, led to long-term depression (LTD) of NMDAR-mediated synaptic transmission. This form of LTD involved the release of Ca2+ from IP₃-sensitive intracellular stores and was expressed via the internalization of NMDARs. Our results suggest that the molecular mechanism involves a dynamic interaction between the neuronal calcium sensor protein hippocalcin, the clathrin adaptor molecule AP2, the postsynaptic density enriched protein PSD-95 and NMDARs. We propose that hippocalcin binds to the SH3 region of PSD-95 under basal conditions, but it translocates to the plasma membrane on sensing Ca2+; in doing so, it causes PSD-95 to dissociate from NMDARs, permitting AP2 to bind and initiate their dynamin-dependent endocytosis.
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94
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Decreased expression of spine-associated Rap guanosine triphosphatase-activating protein (SPAR) in glutamate-treated primary hippocampal neurons. J Clin Neurosci 2010; 17:1042-6. [DOI: 10.1016/j.jocn.2009.12.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 12/09/2009] [Accepted: 12/16/2009] [Indexed: 01/25/2023]
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95
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Variability of distribution of Ca(2+)/calmodulin-dependent kinase II at mixed synapses on the mauthner cell: colocalization and association with connexin 35. J Neurosci 2010; 30:9488-99. [PMID: 20631177 DOI: 10.1523/jneurosci.4466-09.2010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In contrast to chemical transmission, few proteins have been shown associated with gap junction-mediated electrical synapses. Mixed (electrical and glutamatergic) synaptic terminals on the teleost Mauthner cell known as "Club endings" constitute because of their unusual large size and presence of connexin 35 (Cx35), an ortholog of the widespread mammalian Cx36, a valuable model for the study of electrical transmission. Remarkably, both components of their mixed synaptic response undergo activity-dependent potentiation. Changes in electrical transmission result from interactions with colocalized glutamatergic synapses, the activity of which leads to the activation of Ca(2+)/calmodulin-dependent kinase II (CaMKII), required for the induction of changes in both forms of transmission. However, the distribution of this kinase and potential localization to electrical synapses remains undetermined. Taking advantage of the unparalleled experimental accessibility of Club endings, we explored the presence and intraterminal distribution of CaMKII within these terminals. Here we show that (1) unlike other proteins, both CaMKII labeling and distribution were highly variable between contiguous contacts, and (2) CaMKII was not restricted to the periphery of the terminals, in which glutamatergic synapses are located, but also was present at the center in which gap junctions predominate. Accordingly, double immunolabeling indicated that Cx35 and CaMKII were colocalized, and biochemical analysis showed that these proteins associate. Because CaMKII characteristically undergoes activity-dependent translocation, the observed variability of labeling likely reflects physiological differences between electrical synapses of contiguous Club endings, which remarkably coexist with differing degrees of conductance. Together, our results indicate that CaMKII should be considered a component of electrical synapses, although its association is nonobligatory and likely driven by activity.
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96
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Wakade C, Sukumari-Ramesh S, Laird MD, Dhandapani KM, Vender JR. Delayed reduction in hippocampal postsynaptic density protein-95 expression temporally correlates with cognitive dysfunction following controlled cortical impact in mice. J Neurosurg 2010; 113:1195-201. [PMID: 20397893 DOI: 10.3171/2010.3.jns091212] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECT Traumatic brain injury (TBI) induces significant neurological damage, including deficits in learning and memory, which contribute to a poor clinical prognosis. Treatment options to limit cognitive decline and promote neurological recovery are lacking, in part due to a poor understanding of the secondary or delayed processes that contribute to brain injury. In the present study, the authors characterized the temporal and spatial changes in the expression of postsynaptic density protein-95 (PSD-95), a key scaffolding protein implicated in excitatory synaptic signaling, after controlled cortical impacts in mice. Neurological injury, as assessed by the open-field activity test and the novel object recognition test, was compared with changes in PSD-95 expression. METHODS Adult male CD-1 mice were subjected to controlled cortical impacts to simulate moderate TBI in humans. The spatial and temporal expression of PSD-95 was analyzed in the cerebral cortex and hippocampus at various time points following injury and sham operations. Neurological assessments were performed to compare changes in PSD-95 with cognitive deficits. RESULTS A significant decrease in PSD-95 expression was observed in the ipsilateral hippocampus beginning on Day 7 postinjury. The loss of PSD-95 corresponded with a concomitant reduction in immunoreactivity for NeuN (neuronal nuclei), a neuron-specific marker. Aside from the contused cortex, a significant loss of PSD-95 immunoreactivity was not observed in the cerebral cortex. The delayed loss of hippocampal PSD-95 directly correlated with the onset of behavioral deficits, suggesting a possible causative role for PSD-95 in behavioral abnormalities following head trauma. CONCLUSIONS A delayed loss of hippocampal synapses was observed following head trauma in mice. These data may suggest a cellular mechanism to explain the delayed learning and memory deficits in humans after TBI and provide a potential framework for further testing to implicate PSD-95 as a clinically relevant therapeutic target.
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Affiliation(s)
- Chandramohan Wakade
- Department of Neurosurgery, Medical College of Georgia, Augusta, Georgia 30912, USA
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Clapp P, Gibson ES, Dell'acqua ML, Hoffman PL. Phosphorylation regulates removal of synaptic N-methyl-D-aspartate receptors after withdrawal from chronic ethanol exposure. J Pharmacol Exp Ther 2009; 332:720-9. [PMID: 20008487 DOI: 10.1124/jpet.109.158741] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Alterations in N-methyl-d-aspartate receptor (NMDAR) protein levels or subcellular localization in brain after chronic ethanol exposure may contribute to withdrawal-associated seizures and neurotoxicity. We have investigated synaptic localization of NMDARs in cultured hippocampal pyramidal neurons after prolonged (7 days) exposure to, and acute withdrawal from, 80 mM ethanol using fluorescence immunocytochemistry techniques. After chronic ethanol exposure, there was a significant increase in the clustering of NR1 and NR2B subunits and their colocalization with the synaptic proteins synaptophysin and postsynaptic density protein 95, respectively. There was also increased expression of NR1 variants containing the C2' cassette after chronic ethanol exposure. The ethanol-induced synaptic clustering and colocalization were rapidly reversed within 4 h after ethanol withdrawal. Surface labeling of NR2B subunits suggested that this rapid reversal involved lateral receptor movement to extrasynaptic sites rather than internalization of receptors. Receptor removal from the synapse during ethanol withdrawal was associated with changes in the phosphorylation state of NR2B Ser1480, controlled by the protein kinase CK2. The redistribution of NMDAR to synapses produced by long-term ethanol exposure, as well as the rapid removal during withdrawal, may not only affect neuronal withdrawal hyperexcitability but also may sensitize the system to subsequent synaptic plasticity.
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Affiliation(s)
- Peter Clapp
- University of Colorado Denver, School of Medicine, MS 8303, P.O. Box 6511, 12800 E. 19th Avenue, Aurora, CO 80045, USA
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Mandal M, Yan Z. Phosphatidylinositol (4,5)-bisphosphate regulation of N-methyl-D-aspartate receptor channels in cortical neurons. Mol Pharmacol 2009; 76:1349-59. [PMID: 19770351 DOI: 10.1124/mol.109.058701] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The membrane phospholipid phosphatidylinositol (4,5)-bisphosphate (PIP(2)) has been implicated in the regulation of several ion channels and transporters. In this study, we examined the impact of PIP(2) on N-methyl-D-aspartate receptors (NMDARs) in cortical neurons. Blocking PIP(2) synthesis by inhibiting phosphoinositide-4 kinase, or stimulating PIP(2) hydrolysis via activation of phospholipase C (PLC), or blocking PIP(2) function with an antibody caused a significant reduction of NMDAR-mediated currents. On the other hand, inhibition of PLC or application of PIP(2) caused an enhancement of NMDAR currents. These electrophysiological effects were accompanied by changes in NMDAR surface clusters induced by agents that manipulate PIP(2) levels. The PIP(2) regulation of NMDAR currents was abolished by the dynamin inhibitory peptide, which blocks receptor internalization. Agents perturbing actin stability prevented PIP(2) regulation of NMDAR currents, suggesting the actin-dependence of this effect of PIP(2). Cofilin, a major actin depolymerizing factor, which has a common binding sequence for actin and PIP(2), was required for PIP(2) regulation of NMDAR currents. It is noteworthy that the PIP(2) regulation of NMDAR channels was impaired in a transgenic mouse model of Alzheimer's disease, probably because of the amyloid-beta disruption of PIP(2) metabolism. Taken together, our data suggest that continuous synthesis of PIP(2) at the membrane might be important for the maintenance of NMDARs at the cell surface. When PIP(2) is lost, cofilin is released from the PIP(2) complex and is rendered free to depolymerize actin. With the actin cytoskeleton no longer intact, NMDARs are internalized via a dynamin/clathrin-dependent mechanism, leading to reduced NMDAR currents.
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Affiliation(s)
- Madhuchhanda Mandal
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, USA
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Interaction of postsynaptic density protein-95 with NMDA receptors influences excitotoxicity in the yeast artificial chromosome mouse model of Huntington's disease. J Neurosci 2009; 29:10928-38. [PMID: 19726651 DOI: 10.1523/jneurosci.2491-09.2009] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Evidence suggests that NMDA-type glutamate receptors contribute to degeneration of striatal medium-sized spiny neurons (MSNs) in Huntington's disease (HD). Previously, we demonstrated that NMDA receptor (NMDAR)-mediated current and/or toxicity is increased in MSNs from the yeast artificial chromosome (YAC) transgenic mouse model expressing polyglutamine (polyQ)-expanded (mutant) full-length human huntingtin (htt). Others have shown that membrane-associated guanylate kinases (MAGUKs), such as PSD-95 and SAP102, modulate NMDAR surface expression and excitotoxicity in hippocampal and cortical neurons and that htt interacts with PSD-95. Here, we tested the hypothesis that an altered association between MAGUKs and NMDARs in mutant huntingtin-expressing cells contributes to increased susceptibility to excitotoxicity. We show that htt coimmunoprecipitated with SAP102 in HEK293T cells and striatal tissue from wild-type and YAC transgenic mice; however, the association of SAP102 with htt or the NMDAR NR2B subunit was unaffected by htt polyQ length, whereas association of PSD-95 with NR2B in striatal tissue was enhanced by increased htt polyQ length. Treatment of cultured MSNs with Tat-NR2B9c peptide blocked binding of NR2B with SAP102 and PSD-95 and reduced NMDAR surface expression by 20% in both YAC transgenic and wild-type MSNs, and also restored susceptibility to NMDAR excitoxicity in YAC HD MSNs to levels observed in wild-type MSNs; a similar effect on excitotoxicity was observed after knockdown of PSD-95 by small interfering RNA. Unlike previous findings in cortical and hippocampal neurons, rescue of NMDA toxicity by Tat-NR2B9c occurred independently of any effect on neuronal nitric oxide synthase activity. Our results elucidate further the mechanisms underlying enhanced excitotoxicity in HD.
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Chang LR, Liu JP, Zhang N, Wang YJ, Gao XL, Wu Y. Different expression of NR2B and PSD-95 in rat hippocampal subregions during postnatal development. Microsc Res Tech 2009; 72:517-24. [PMID: 19306263 DOI: 10.1002/jemt.20708] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The different expressions of NR2 and synaptic-associated proteins have been studied by protein and mRNA level with immunoblotting, in situ hybridization, or immunogold analysis. But the relationship between NR2 subunits and PSD-95 family proteins is still controversial. In this study, we used immunofluorescent staining to assess NR2B and PSD-95 expressions and the relationship between them in CA1, CA3, and DG of rat hippocampus on different postnatal day. In CA1, NR2B expression decreased with age. It was high at birth, reached a plateau at P4, and declined gradually after P7. In CA3, NR2B expression was similar to that in CA1. But the stratum lucidum was devoid of staining. In DG, the NR2B expression retained a higher level. From P0 to P2, the PSD-95 expression in CA1 increased gently, and then declined slightly. After P7, the PSD-95 expression increased sharply till P28, and decreased again. In CA3 and DG, the PSD-95 expression is very similar except that low-level of PSD-95 was found in the CA3 stratum lucidum. The expression of NR2B did not correlate with that of PSD-95 in CA1 and the DG granular and molecular layer. Only in CA3 and DG polymorphic layer, there was a negative correlation. The results suggested in hippocampal subregions, CA3 and DG may be more plastic than CA1.The NR2B and PSD-95 expression have distinct regional and cell specific distribution. The different regional distribution pattern may relate to the different physiological functions during postnatal development.
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Affiliation(s)
- Li-Rong Chang
- Department of Anatomy, Capital Medical University, Beijing 100069, China
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