151
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Upton N, Chuang TT, Hunter AJ, Virley DJ. 5-HT6 receptor antagonists as novel cognitive enhancing agents for Alzheimer's disease. Neurotherapeutics 2008; 5:458-69. [PMID: 18625457 PMCID: PMC5084247 DOI: 10.1016/j.nurt.2008.05.008] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Alzheimer's disease (AD) is a devastating neurological condition characterized by a progressive decline in cognitive performance accompanied by behavioral and psychological syndromes, such as depression and psychosis. The neurochemical correlates of these clinical manifestations now appear to involve dysfunctions of multiple neurotransmitter pathways. Because of the extensive serotonergic denervation that has been observed in the AD brain and the important role played by serotonin (5-HT) in both cognition and behavioral control, this neurotransmitter system has become a focus of concerted research efforts to identify new treatments for AD. 5-HT exerts its diverse physiological and pharmacological effects through actions on multiple receptor subtypes. One of the newest members of this family is the 5-HT6 receptor, a subtype localized almost exclusively in the CNS, predominating in brain regions associated with cognition and behavior. With the subsequent development of selective 5-HT6 receptor antagonists, preclinical studies in rodents and primates have elucidated the function of this receptor subtype in more detail. It is increasingly clear that blockade of 5-HT6 receptors leads to an improvement of cognitive performance in a wide variety of learning and memory paradigms and also results in anxiolytic and antidepressant-like activity. These actions are largely underpinned by enhancements of cholinergic, glutamatergic, noradrenergic, and dopaminergic neurotransmission, together with learning-associated neuronal remodeling. A preliminary report that the cognitive enhancing properties of a 5-HT6 receptor antagonist (namely, SB-742457) extends into AD sufferers further highlights the therapeutic promise of this mechanistic approach.
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Affiliation(s)
- Neil Upton
- GlaxoSmithKline, New Frontiers Science Park, Third Avenue, Harlow, Essex, United Kingdom.
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152
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Theodosis DT, Poulain DA, Oliet SHR. Activity-Dependent Structural and Functional Plasticity of Astrocyte-Neuron Interactions. Physiol Rev 2008; 88:983-1008. [DOI: 10.1152/physrev.00036.2007] [Citation(s) in RCA: 387] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Observations from different brain areas have established that the adult nervous system can undergo significant experience-related structural changes throughout life. Less familiar is the notion that morphological plasticity affects not only neurons but glial cells as well. Yet there is abundant evidence showing that astrocytes, the most numerous cells in the mammalian brain, are highly mobile. Under physiological conditions as different as reproduction, sensory stimulation, and learning, they display a remarkable structural plasticity, particularly conspicuous at the level of their lamellate distal processes that normally ensheath all portions of neurons. Distal astrocytic processes can undergo morphological changes in a matter of minutes, a remodeling that modifies the geometry and diffusion properties of the extracellular space and relationships with adjacent neuronal elements, especially synapses. Astrocytes respond to neuronal activity via ion channels, neurotransmitter receptors, and transporters on their processes; they transmit information via release of neuroactive substances. Where astrocytic processes are mobile then, astrocytic-neuronal interactions become highly dynamic, a plasticity that has important functional consequences since it modifies extracellular ionic homeostasis, neurotransmission, gliotransmission, and ultimately neuronal function at the cellular and system levels. Although a complete picture of intervening cellular mechanisms is lacking, some have been identified, notably certain permissive molecular factors common to systems capable of remodeling (cell surface and extracellular matrix adhesion molecules, cytoskeletal proteins) and molecules that appear specific to each system (neuropeptides, neurotransmitters, steroids, growth factors) that trigger or reverse the morphological changes.
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153
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Favre-Kontula L, Rolland A, Bernasconi L, Karmirantzou M, Power C, Antonsson B, Boschert U. GlialCAM, an immunoglobulin-like cell adhesion molecule is expressed in glial cells of the central nervous system. Glia 2008; 56:633-45. [PMID: 18293412 DOI: 10.1002/glia.20640] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Using structure based genome mining targeting vascular endothelial and platelet derived growth factor immunoglobulin (Ig) like folds, we have identified a sequence corresponding to a single transmembrane protein with two Ig domains, which we cloned from a human brain cDNA library. The cDNA is identical to hepatocyte cell adhesion molecule (hepaCAM), which was originally described as a tumor suppressor gene in liver. Here, we show that the protein is predominantly expressed in the mouse and human nervous system. In liver, the expression is very low in humans, and is not detected in mice. To identify the central nervous system (CNS) regions and cell types expressing the protein, we performed a LacZ reporter gene assay on heterozygous mice in which one copy of the gene encoding the novel protein had been replaced with beta-galactosidase. beta-galactosidase expression was prominent in white matter tracts of the CNS. Furthermore, expression was detected in ependymal cells of the brain ventricular zones and the central canal of the spinal cord. Double labeling experiments showed expression mainly in CNPase positive oligodendrocytes (OL). Since the protein is predominantly expressed in the CNS glial cells, we named the molecule glial cell adhesion molecule (GlialCAM). A potential role for GlialCAM in myelination was supported by its up-regulation during postnatal mouse brain development, where it was concomitantly expressed with myelin basic protein (MBP). In addition, in vitro, GlialCAM was observed in various developmental stages of OL and in astrocytes in processes and at cell contact sites. In A2B5 positive OL, GlialCAM colocalizes with GAP43 in OL growth cone like structures. Overall, the data presented here indicate a potential function for GlialCAM in glial cell biology.
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Affiliation(s)
- Linda Favre-Kontula
- Protein and Cell Sciences, Merck Serono, Geneva Research Center, Geneva, Switzerland
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154
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Maćkowiak M, Grzegorzewska M, Budziszewska B, Chocyk A, Hess G, Wędzony K. Cocaine decreases the expression of PSA-NCAM protein and attenuates long-term potentiation via glucocorticoid receptors in the rat dentate gyrus. Eur J Neurosci 2008; 27:2928-37. [DOI: 10.1111/j.1460-9568.2008.06255.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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155
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Schmid RS, Maness PF. L1 and NCAM adhesion molecules as signaling coreceptors in neuronal migration and process outgrowth. Curr Opin Neurobiol 2008; 18:245-50. [PMID: 18760361 PMCID: PMC2633433 DOI: 10.1016/j.conb.2008.07.015] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 07/30/2008] [Accepted: 07/31/2008] [Indexed: 01/08/2023]
Abstract
Neural cell adhesion molecules (CAMs) of the immunoglobulin superfamily engage in multiple neuronal interactions that influence cell migration, axonal and dendritic projection, and synaptic targeting. Their downstream signal transduction events specify whether a cell moves or projects axons and dendrites to targets in the brain. Many of the diverse functions of CAMs are brought about through homophilic and heterophilic interactions with other cell surface receptors. An emerging concept is that CAMs act as coreceptors to assist in intracellular signal transduction, and to provide cytoskeletal linkage necessary for cell and growth cone motility. Here we will focus on new discoveries that have revealed novel coreceptor functions for the best-understood CAMs--L1, CHL1, and NCAM--important for neuronal migration and axon guidance. We will also discuss how dysregulation of CAMs may also bear on neuropsychiatric disease and cancer.
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Affiliation(s)
- Ralf S. Schmid
- Center for Drug Discovery and Department of Neurobiology, Duke University Medical Center, Durham, NC 27704, Ph: 919-425-2576, Fax: 919477-0664,
| | - Patricia F. Maness
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC 27599, Ph: 919-966-2323, Fax: 919-966-2154,
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156
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157
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Affiliation(s)
- Heather E. Murrey
- Division of Chemistry and Chemical Engineering and Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California 91125
| | - Linda C. Hsieh-Wilson
- Division of Chemistry and Chemical Engineering and Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California 91125
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158
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Hansen SM, Li S, Bock E, Berezin V. WITHDRAWN: Synthetic NCAM-derived Ligands of the Fibroblast Growth Factor Receptor. Neurochem Res 2008. [PMID: 18427984 DOI: 10.1007/s11064-008-9707-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/03/2008] [Indexed: 10/22/2022]
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159
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Muller D, Mendez P, De Roo M, Klauser P, Steen S, Poglia L. WITHDRAWN: Role of NCAM in Spine Dynamics and Synaptogenesis. Neurochem Res 2008. [PMID: 18351460 DOI: 10.1007/s11064-008-9653-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Accepted: 03/04/2008] [Indexed: 09/29/2022]
Abstract
Increasing evidence indicates that adhesion molecules are critically involved in the regulation of mechanisms of synaptic plasticity including synapse formation, but also synaptic remodeling associated to changes in synaptic strength. Among these, the Neural Cell Adhesion Molecule (NCAM) and its polysialylated form PSA-NCAM are important candidates. Here we review recent results that point to a possible role of these two molecules in regulating the structural properties of excitatory synapses and namely the composition and stability of the postsynaptic density, thereby accounting for their contribution to mechanisms of synaptogenesis and activity-dependent synaptic plasticity.
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Affiliation(s)
- D Muller
- Department of Neuroscience, University of Geneva Medical Center, 1. M. Servet, 1211, Geneva 4, Switzerland,
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160
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Stewart M, Popov V, Medvedev N, Gabbott P, Corbett N, Kraev I, Davies H. WITHDRAWN: Dendritic Spine and Synapse Morphological Alterations Induced by a Neural Cell Adhesion Molecule (NCAM) Mimetic. Neurochem Res 2008. [PMID: 18338259 DOI: 10.1007/s11064-008-9607-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Accepted: 01/24/2008] [Indexed: 09/29/2022]
Abstract
The neural cell adhesion molecule (NCAM) is a glycoprotein expressed on the surface of neurons and glial cells. It plays a key role in morphogenesis of the nervous system, regeneration of damaged neural tissue and synaptic plasticity. The extracellular domain of NCAM engages in homophilic interactions (NCAM binding to NCAM) and in heterophilic interactions between NCAM and other proteins such as the fibroblast growth factor (FGF) receptor. It promotes synaptogenesis and activity-dependent remodelling of synapses but less is know of its influence on synaptic and dendritic morphology. Recently, quantitative electron microscopy and 3-dimensional reconstruction (3-D) of ultrathin serial sections has been used to examine the morphology of synapses and dendritic spines in the hippocampus of rats treated with a neural cell adhesion molecule-derived fibroblast growth factor receptor agonist, FGL-peptide (an NCAM mimetic). These data show clearly that the FGL peptide has marked influences on both spine and synaptic form.
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Affiliation(s)
- Michael Stewart
- Faculty of Sciences, Department of Life Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK,
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161
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Natori T, Kodaira F, Hirasawa T, Gao YY, Nagai K. Augmentation of Polysialic Acid by Valproic Acid in Early Postnatal Mouse Hippocampus and Primary Cultured Hippocampal Neurons. J Biosci Bioeng 2008; 105:164-7. [DOI: 10.1263/jbb.105.164] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Accepted: 11/22/2007] [Indexed: 11/17/2022]
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162
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Hildebrandt H, Mühlenhoff M, Weinhold B, Gerardy-Schahn R. Dissecting polysialic acid and NCAM functions in brain development. J Neurochem 2008; 103 Suppl 1:56-64. [PMID: 17986140 DOI: 10.1111/j.1471-4159.2007.04716.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The unique modification of the neural cell adhesion molecule (NCAM) by polysialic acid (polySia) is tightly associated with nervous system development and plasticity. The prevailing view that this large carbohydrate polymer acts as an anti-adhesive factor seems straightforward at first sight. However, during almost 25 years of polySia research it became increasingly clear that the impact of polySia on cell surface interactions can not be explained by one unifying mechanism. Recent progress in the generation of mouse models, which partially or completely lack polySia due to ablation of one or both of the two polySia synthesizing enzymes, provides novel insights into the function of this unique post-translational modification. The present review is focused on a phenotype comparison between the newly established mouse strains which combine polySia-deficiency with normal NCAM expression and the well-characterized NCAM negative mouse model. Analysis of shared and individual phenotypes allows a clear distinction between NCAM and polySia functions and revealed that polySia plays a vital role as a specific control element of NCAM-mediated interactions.
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Affiliation(s)
- Herbert Hildebrandt
- Zelluläre Chemie, Zentrum Biochemie, Medizinische Hochschule Hannover, Hannover, Germany.
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163
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Oltmann-Norden I, Galuska SP, Hildebrandt H, Geyer R, Gerardy-Schahn R, Geyer H, Mühlenhoff M. Impact of the Polysialyltransferases ST8SiaII and ST8SiaIV on Polysialic Acid Synthesis during Postnatal Mouse Brain Development. J Biol Chem 2008; 283:1463-1471. [DOI: 10.1074/jbc.m708463200] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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164
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Polysialic acid in the plasticity of the developing and adult vertebrate nervous system. Nat Rev Neurosci 2008; 9:26-35. [DOI: 10.1038/nrn2285] [Citation(s) in RCA: 479] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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165
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Kiryushko D, Bock E, Berezin V. Pharmacology of cell adhesion molecules of the nervous system. Curr Neuropharmacol 2007; 5:253-67. [PMID: 19305742 PMCID: PMC2644493 DOI: 10.2174/157015907782793658] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 04/27/2007] [Accepted: 07/17/2007] [Indexed: 12/15/2022] Open
Abstract
Cell adhesion molecules (CAMs) play a pivotal role in the development and maintenance of the nervous system under normal conditions. They also are involved in numerous pathological processes such as inflammation, degenerative disorders, and cancer, making them attractive targets for drug development. The majority of CAMs are signal transducing receptors. CAM-induced intracellular signalling is triggered via homophilic (CAM-CAM) and heterophilic (CAM - other counter-receptors) interactions, which both can be targeted pharmacologically. We here describe the progress in the CAM pharmacology focusing on cadherins and CAMs of the immunoglobulin (Ig) superfamily, such as NCAM and L1. Structural basis of CAM-mediated cell adhesion and CAM-induced signalling are outlined. Different pharmacological approaches to study functions of CAMs are presented including the use of specific antibodies, recombinant proteins, and synthetic peptides. We also discuss how unravelling of the 3D structure of CAMs provides novel pharmacological tools for dissection of CAM-induced signalling pathways and offers therapeutic opportunities for a range of neurological disorders.
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Affiliation(s)
- Darya Kiryushko
- Protein Laboratory, Department of Neuroscience and Pharmacology, Panum Institute Bld. 6.2, Blegdamsvej 3C, DK-2200, Copenhagen N, Denmark.
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166
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Di Cristo G, Chattopadhyaya B, Kuhlman SJ, Fu Y, Bélanger MC, Wu CZ, Rutishauser U, Maffei L, Huang ZJ. Activity-dependent PSA expression regulates inhibitory maturation and onset of critical period plasticity. Nat Neurosci 2007; 10:1569-77. [PMID: 18026099 DOI: 10.1038/nn2008] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Accepted: 10/05/2007] [Indexed: 11/09/2022]
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167
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Gascon E, Vutskits L, Kiss JZ. Polysialic acid–neural cell adhesion molecule in brain plasticity: From synapses to integration of new neurons. ACTA ACUST UNITED AC 2007; 56:101-18. [PMID: 17658613 DOI: 10.1016/j.brainresrev.2007.05.014] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2007] [Revised: 04/02/2007] [Accepted: 05/24/2007] [Indexed: 11/15/2022]
Abstract
Isoforms of the neuronal cell adhesion molecule (NCAM) carrying the linear homopolymer of alpha 2,8-linked sialic acid (polysialic acid, PSA) have emerged as particularly attractive candidates for promoting plasticity in the nervous system. The large negatively charged PSA chain of NCAM is postulated to be a spacer that reduces adhesion forces between cells allowing dynamic changes in membrane contacts. Accumulating evidence also suggests that PSA-NCAM-mediated interactions lead to activation of intracellular signaling cascades that are fundamental to the biological functions of the molecule. An important role of PSA-NCAM appears to be during development, when its expression level is high and where it contributes to the regulation of cell shape, growth or migration. However, PSA-NCAM does persist in adult brain structures such as the hippocampus that display a high degree of plasticity where it is involved in activity-induced synaptic plasticity. Recent advances in the field of PSA-NCAM research have not only consolidated the importance of this molecule in plasticity processes but also suggest a role for PSA-NCAM in the regulation of higher cognitive functions and psychiatric disorders. In this review, we discuss the role and mode of actions of PSA-NCAM in structural plasticity as well as its potential link to cognitive processes.
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Affiliation(s)
- Eduardo Gascon
- Department of Neuroscience, University of Geneva Medical School, 1, Rue Michel Servet, CH-1211, Geneva, Switzerland
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168
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Bukalo O, Dityatev A. Analysis of neural cell functions in gene knockout mice: electrophysiological investigation of synaptic plasticity in acute hippocampal slices. Methods Enzymol 2007; 417:52-66. [PMID: 17132497 DOI: 10.1016/s0076-6879(06)17005-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Several knockout mice deficient in transferases, required for glycosylation of cell adhesion and extracellular matrix molecules, have recently been produced. Extracellular recordings of field excitatory postsynaptic potentials in acute hippocampal slices prepared from these mutant mice proved to be a highly sensitive method to reveal the roles of transferases and related carbohydrates in synaptic transmission and plasticity. Although most available data have been collected for synaptic connections between CA3 and CA1 pyramidal cells, several other synapses are assessable for extracellular recording in the hippocampus, including connections between mossy fibers and CA3 pyramidal cells. Analysis of distinct forms of short- and long-term plasticity in these connections may be instrumental for dissection of mechanisms by which carbohydrates affect synaptic functions.
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Affiliation(s)
- Olena Bukalo
- Zentrum fuer Molekulare Neurobiologie, Universitaetsklinikum Hamburg-Eppendorf, Hamburg, Germany
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169
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Atz ME, Rollins B, Vawter MP. NCAM1 association study of bipolar disorder and schizophrenia: polymorphisms and alternatively spliced isoforms lead to similarities and differences. Psychiatr Genet 2007; 17:55-67. [PMID: 17413444 PMCID: PMC2077086 DOI: 10.1097/ypg.0b013e328012d850] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE The neural cell adhesion molecule (NCAM1) is a multifunction transmembrane protein involved in synaptic plasticity, neurodevelopment, and neurogenesis. Multiple NCAM1 proteins were differentially altered in bipolar disorder and schizophrenia. Single nucleotide polymorphisms (SNPs) in the NCAM1 gene were significantly associated with bipolar disorder in the Japanese population. Bipolar disorder and schizophrenia may share common vulnerability or susceptibility risk factors for shared features in each disorder. METHODS Both SNPs and splice variants in the NCAM1 gene were analysed in bipolar disorder and schizophrenia. A case-control study design for association of SNPs and differential exon expression in the NCAM1 gene was used. RESULTS A genotypic association between bipolar disorder and SNP b (rs2303377 near mini-exon b) and a suggestive association between schizophrenia and SNP 9 (rs646558) were found. Three of the two marker haplotypes for SNP 9 and SNP b showed varying frequencies between bipolar and controls (P<0.0001) as well as between schizophrenia and controls (P<0.0001). There were nine NCAM1 transcripts present in postmortem brain samples that involve alternative splicing of NCAM1 mini-exons (a, b, c) and the secreted (SEC) exon. Significant differences in the amounts of four alternatively spliced isoforms were found between NCAM1 SNP genotypes. In exploratory analysis, the c-SEC alternative spliced isoform was significantly decreased in bipolar disorder compared to controls for NCAM1 SNP b heterozygotes (P=0.013). CONCLUSIONS Diverse NCAM1 transcripts were found with possibly different functions. The results suggest that SNPs within NCAM1 contribute differential risk for both bipolar disorder and schizophrenia possibly by alternative splicing of the gene.
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Affiliation(s)
- Mary E Atz
- Department of Psychiatry and Human Behavior, University of California, Irvine, California, USA
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170
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Tian L, Stefanidakis M, Ning L, Van Lint P, Nyman-Huttunen H, Libert C, Itohara S, Mishina M, Rauvala H, Gahmberg CG. Activation of NMDA receptors promotes dendritic spine development through MMP-mediated ICAM-5 cleavage. ACTA ACUST UNITED AC 2007; 178:687-700. [PMID: 17682049 PMCID: PMC2064474 DOI: 10.1083/jcb.200612097] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Matrix metalloproteinase (MMP)-2 and -9 are pivotal in remodeling many tissues. However, their functions and candidate substrates for brain development are poorly characterized. Intercellular adhesion molecule-5 (ICAM-5; Telencephalin) is a neuronal adhesion molecule that regulates dendritic elongation and spine maturation. We find that ICAM-5 is cleaved from hippocampal neurons when the cells are treated with N-methyl-d-aspartic acid (NMDA) or α-amino-3-hydroxy-5-methylisoxazole-propionic acid (AMPA). The cleavage is blocked by MMP-2 and -9 inhibitors and small interfering RNAs. Newborn MMP-2– and MMP-9–deficient mice brains contain more full-length ICAM-5 than wild-type mice. NMDA receptor activation disrupts the actin cytoskeletal association of ICAM-5, which promotes its cleavage. ICAM-5 is mainly located in dendritic filopodia and immature thin spines. MMP inhibitors block the NMDA-induced cleavage of ICAM-5 more efficiently in dendritic shafts than in thin spines. ICAM-5 deficiency causes retraction of thin spine heads in response to NMDA stimulation. Soluble ICAM-5 promotes elongation of dendritic filopodia from wild-type neurons, but not from ICAM-5–deficient neurons. Thus, MMPs are important for ICAM-5–mediated dendritic spine development.
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Affiliation(s)
- Li Tian
- Division of Biochemistry, Department of Biological and Environmental Sciences, Faculty of Biosciences, University of Helsinki, FIN-00014 Helsinki, Finland.
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171
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Parkash J, Kaur G. Potential of PSA-NCAM in neuron-glial plasticity in the adult hypothalamus: role of noradrenergic and GABAergic neurotransmitters. Brain Res Bull 2007; 74:317-28. [PMID: 17845906 DOI: 10.1016/j.brainresbull.2007.07.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Revised: 07/02/2007] [Accepted: 07/03/2007] [Indexed: 11/30/2022]
Abstract
The present study was designed to establish the dynamic regulation of polysialylated form of neural cell adhesion molecule (PSA-NCAM) expression by neurotransmitters controlling gonadotropin releasing hormone (GnRH) secretion. The expression of PSA-NCAM and glial fibrillary acidic protein (GFAP) on GnRH cell bodies and axon terminals in the medial preoptic area (mPOA) and median eminence-arcuate (ME-ARC) region of hypothalamus was studied in the proestrous phase of cycling rats treated with alpha-adrenergic receptor blocker phenoxybenzamine (PBZ) and gamma-aminobutyric acid (GABA) by using dual immunohistofluorescent staining and Western blot hybridization. To further elucidate whether activity mediated regulation of PSA-NCAM in GnRH neuron is via regulation of PSA biosynthesis by polysialytransferase (PST) enzyme, the expression of PST-1 enzyme was studied by using fluorescent in situ hybridization (FISH). Both GnRH and PSA-NCAM immunostaining was much higher in the mPOA and ME-ARC region from proestrous phase rats, whereas, PBZ and GABA treatments significantly reduced their expression, GFAP-ir and its content were increased in the PBZ and GABA treated proestrous rats. Taken together, our observations add to the growing evidence that PSA-NCAM plays permissive role for neuronal-glial remodeling and further suggest a functional link between activity dependent structural remodeling in GnRH neurons. Further, enhanced mRNA expression of PST suggests that the biosynthesis of PSA on NCAM is regulated at the transcriptional level.
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Affiliation(s)
- Jyoti Parkash
- Department of Biotechnology, Guru Nanak Dev University, Amritsar 143005, Punjab, India
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172
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Varea E, Castillo-Gómez E, Gómez-Climent MA, Blasco-Ibáñez JM, Crespo C, Martínez-Guijarro FJ, Nàcher J. Chronic antidepressant treatment induces contrasting patterns of synaptophysin and PSA-NCAM expression in different regions of the adult rat telencephalon. Eur Neuropsychopharmacol 2007; 17:546-57. [PMID: 17307340 DOI: 10.1016/j.euroneuro.2007.01.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Revised: 11/30/2006] [Accepted: 01/09/2007] [Indexed: 11/20/2022]
Abstract
Structural modifications occur in the brain of severely depressed patients and they can be reversed by antidepressant treatment. Some of these changes do not occur in the same direction in different regions, such as the medial prefrontal cortex, the hippocampus or the amygdala. Differential structural plasticity also occurs in animal models of depression and it is also prevented by antidepressants. In order to know whether chronic fluoxetine treatment induces differential neuronal structural plasticity in rats, we have analyzed the expression of synaptophysin, a protein considered a marker of synaptic density, and the expression of the polysialylated form of the neural cell adhesion molecule (PSA-NCAM), a molecule involved in neurite and synaptic remodeling. Chronic fluoxetine treatment increases synaptophysin and PSA-NCAM expression in the medial prefrontal cortex and decreases them in the amygdala. The expression of these molecules is also affected in the entorhinal, the visual and the somatosensory cortices.
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Affiliation(s)
- E Varea
- Neurobiology Unit and Program in Basic and Applied Neurosciences, Cell Biology Department, Universitat de València, Spain
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173
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Murphy JA, Nickerson PEB, Clarke DB. Injury to retinal ganglion cell axons increases polysialylated neural cell adhesion molecule (PSA-NCAM) in the adult rodent superior colliculus. Brain Res 2007; 1163:21-32. [PMID: 17631281 DOI: 10.1016/j.brainres.2007.05.069] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Revised: 05/15/2007] [Accepted: 05/21/2007] [Indexed: 11/27/2022]
Abstract
The adult mammalian central nervous system (CNS) exhibits a limited regenerative response to injury. It is well established that polysialylated neural cell adhesion molecule (PSA-NCAM) contributes to nervous system plasticity. In the visual system, PSA-NCAM participates in retinal ganglion cell (RGC) axon growth during development and specifically influences RGC innervation of its principle target tissue, the superior colliculus (SC). The goals of this study were to determine whether PSA-NCAM is expressed in the normal adult mouse SC and to evaluate PSA-NCAM expression following RGC injury. In the normal rostral, but not caudal, SC we find that PSA-NCAM is present in the retinorecipient layers; however, PSA-NCAM and RGC axons do not co-localize. In the deeper collicular layers, PSA-NCAM is observed as several distinct patches that occur at the same depth along the medial-lateral axis throughout the colliculus. RGC axotomy denervates predominantly the contralateral colliculus, where increased PSA-NCAM levels are seen at 7 and 10 days after the injury. Further evaluation of the retinorecipient layers of the partially denervated SC reveals that some intact CTB-traced RGC axons (less than 5%) labeled from the ipsilateral eye do co-localize with PSA-NCAM. This study is the first characterization of PSA-NCAM expression in the normal and partially denervated adult SC and may indicate that PSA-NCAM is involved in attempted visual system remodeling after injury.
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Affiliation(s)
- J A Murphy
- Neuron Survival and Regeneration Laboratory, Department of Anatomy and Neurobiology, Faculty of Medicine, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, Canada B3H 1X5
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174
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Singh J, Kaur G. Transcriptional regulation of polysialylated neural cell adhesion molecule expression by NMDA receptor activation in retinoic acid-differentiated SH-SY5Y neuroblastoma cultures. Brain Res 2007; 1154:8-21. [PMID: 17499225 DOI: 10.1016/j.brainres.2007.04.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2006] [Revised: 03/19/2007] [Accepted: 04/03/2007] [Indexed: 12/31/2022]
Abstract
NMDA receptors exhibit a dichotomy of signaling with excessive stimulation leading to neuronal damage that occurs during neurodegenerative disorders, whereas the normal burst of activity results in plastic responses with the expression of molecular substrates of long-term plasticity, growth and survival. Control of polysialylated neural cell adhesion molecule (PSA-NCAM) expression by NMDA receptor activation has been described in several systems, suggesting a functional link between these two proteins. The coordinated induction of several different transcription factors initiated by NMDA receptor stimulation may be a key mechanism in the orchestration of specific target gene expression that underlies various aspects of CNS function, including plastic responses. We report here the transcriptional regulation of PSA-NCAM expression by subtoxic dose of NMDA in retinoic acid-differentiated SH-SY5Y cell cultures. SH-SY5Y cell cultures differentiated with retinoic acid (10 microM) were exposed to NMDA (100 microM) or to antagonist MK-801 (200 nM) prior to treatment with NMDA and cells were harvested after 24 h of treatment to study the expression of PSA-NCAM, nuclear factor kappaB (NF-kappaB) and activator protein-1 (AP-1) by Western blotting and dual immunocytofluorescence and expression of polysialyltransferase (PST) mRNA by fluorescent in situ hybridization (FISH). We observed the induction of transcription factors NF-kappaB and AP-1 along with PSA-NCAM expression in response to NMDA receptor activation. Also, PSA-NCAM regulation in response to NMDA receptor activity was shown to be transcriptionally controlled, as seen by temporal and spatial changes observed in the expression of PST mRNA in NMDA-treated SH-SY5Y cell cultures. This raises the interesting possibility that NF-kappaB and AP-1 expression is involved in propagating the signals of NMDA receptor activity that leads to downstream strengthening of long-term plasticity changes in differentiated SH-SY5Y neuroblastoma cell cultures. Thus understanding the regulation of PSA-NCAM expression by NMDA receptor-mediated activity may represent a fundamental prerequisite for the development of therapies in order to maintain neuronal plasticity throughout life and functional recovery after brain damage.
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Affiliation(s)
- Jaspreet Singh
- Department of Biotechnology, Guru Nanak Dev University, Amritsar-143005 (Pb) Punjab, India
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175
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von Bohlen Und Halbach O. Immunohistological markers for staging neurogenesis in adult hippocampus. Cell Tissue Res 2007; 329:409-20. [PMID: 17541643 DOI: 10.1007/s00441-007-0432-4] [Citation(s) in RCA: 318] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Accepted: 04/25/2007] [Indexed: 12/11/2022]
Abstract
Neurogenesis in the adult dentate gyrus (DG) of the hippocampus occurs constitutively throughout postnatal life, and the rate of neurogenesis within the DG can be altered under various physiological and pathophysiological conditions. Adult neurogenesis includes the process in which the division of a precursor cell takes place and the multi-step process (proliferation, differentiation, migration, targeting, and synaptic integration) that ends with the formation of a postmitotic functionally integrated new neuron. During specific time-frames of adult neurogenesis, various markers are expressed that correlate with the differentiation steps along the pathway from early progenitor cells to newly generated postmitotic neurons within the DG. Markers that are currently widely used for the investigation of adult hippocampal neurogenesis are: glial fibrillary acidic protein, nestin, Pax6, NeuroD, PSA-NCAM, doublecortin, TUC-4, Tuj-1, and calretinin. The discovery and development of specific markers that allow the time-course and fate of neurons to be followed during adult neurogenesis in a detailed and precise fashion are not only helpful for gaining further insights into the genesis of new neurons in the hippocampus, but also might be applicable to the development of strategies for therapeutic interventions.
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Affiliation(s)
- O von Bohlen Und Halbach
- Interdisciplinary Center for Neurosciences, Department of Neuroanatomy, University of Heidelberg, Im Neuenheimer Feld 307, 69120 Heidelberg, Germany.
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176
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Maćkowiak M, Chocyk A, Markowicz-Kula K, Wędzony K. Acute activation of CB1 cannabinoid receptors transiently decreases PSA-NCAM expression in the dentate gyrus of the rat hippocampus. Brain Res 2007; 1148:43-52. [DOI: 10.1016/j.brainres.2007.02.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Revised: 02/02/2007] [Accepted: 02/08/2007] [Indexed: 12/13/2022]
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177
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Lopez-Fernandez MA, Montaron MF, Varea E, Rougon G, Venero C, Abrous DN, Sandi C. Upregulation of polysialylated neural cell adhesion molecule in the dorsal hippocampus after contextual fear conditioning is involved in long-term memory formation. J Neurosci 2007; 27:4552-61. [PMID: 17460068 PMCID: PMC6673006 DOI: 10.1523/jneurosci.0396-07.2007] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2006] [Revised: 03/17/2007] [Accepted: 03/17/2007] [Indexed: 12/20/2022] Open
Abstract
The role of the hippocampus in pavlovian fear conditioning is controversial. Although lesion and pharmacological inactivation studies have suggested a key role for the dorsal hippocampus in contextual fear conditioning, the involvement of the ventral part is still uncertain. Likewise, the debate is open with regard to the putative implication of each hippocampal subdivision in fear conditioning to a discrete conditioned stimulus. We explored the potential existence of dissociations occurring in the dorsal versus ventral hippocampus at the cellular level while dealing with either contextual or cued fear conditioning and focused in a molecular "signature" linked to structural plasticity, the polysialylated form of the neural cell adhesion molecule (PSA-NCAM). We found an upregulation of PSA-NCAM expression in the dorsal (but not ventral) dentate gyrus at 24 h after contextual (but not tone) fear conditioning. Specific removal of PSA through microinfusion of the enzyme endoneuraminidase-N in the dorsal (but not ventral) hippocampus reduced freezing responses to the conditioned context. Therefore, we present evidence for a specific role of PSA-NCAM in the dorsal hippocampus in the plasticity processes occurring during consolidation of the context representation after "standard" contextual fear conditioning. Interestingly, we also found that exposing animals just to the context induced an activation of PSA-NCAM in both dorsal and ventral dentate gyrus. Altogether, these findings highlighting the distinctive occurrence of these neuroplastic processes in the dorsal hippocampus during the standard contextual fear-conditioning task enlighten the ongoing debate about the involvement of these hippocampal subdivisions in pavlovian fear conditioning.
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Affiliation(s)
| | - Marie-Françoise Montaron
- Neurogenesis and Pathophysiology Laboratory, Bordeaux Neuroscience Research Center, Institut National de la Santé et de la Recherche Médicale 862 and University of Bordeaux 2, Bordeaux Cedex 33077, France
| | - Emilio Varea
- Brain Mind Institute, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland
| | - Genevieve Rougon
- Centre National de la Recherche Scientifique Unité Mixte de Recherche 6216, Université de la Méditerranée, Institut de Biologie du Développement de Marseille-Luminy Case 907, Marseille Cedex 13288, France
| | - Cesar Venero
- Psychobiology Department, Universidad Nacional de Educacion a Distancia, 28040 Madrid, Spain, and
| | - Djoher Nora Abrous
- Neurogenesis and Pathophysiology Laboratory, Bordeaux Neuroscience Research Center, Institut National de la Santé et de la Recherche Médicale 862 and University of Bordeaux 2, Bordeaux Cedex 33077, France
| | - Carmen Sandi
- Brain Mind Institute, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland
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178
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Meidinger MA, Hildebrandt-Schoenfeld H, Illing RB. Cochlear damage induces GAP-43 expression in cholinergic synapses of the cochlear nucleus in the adult rat: a light and electron microscopic study. Eur J Neurosci 2007; 23:3187-99. [PMID: 16820009 DOI: 10.1111/j.1460-9568.2006.04853.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Recent studies suggest a potential for activity-dependent reconstruction in the adult mammalian brainstem that exceeds previous expectations. We found that a unilateral cochlear lesion led within 1 week to a rise of choline acetyltransferase (ChAT) immunoreactivity in the ventral cochlear nucleus of the affected side, matching the lesion-induced expression of growth-associated protein 43 (GAP-43) previously described. The rise of both ChAT and GAP-43 immunoreactivity was reflected in the average density of the staining. Moreover, the number of light-microscopically identifiable boutons increased in both stains. GAP-43-positive boutons could, by distinct ultrastructural features, regularly be identified as presynaptic endings. However, GAP-43 immunoreactivity was not only found in presynaptic endings with a classical morphology, but also in profiles that suggest morphological dynamic structures by showing filopodia, assemblages of pleomorphic vesicles, large vesicles (diameter up to 200 nm) fusing with the presynaptic plasma membrane close to synaptic contacts, small dense-core vesicles (diameter about 80 nm) and presynaptic ribosomes. Moreover, we observed perforated synapses as well as GAP-43 immunoreactivity condensed in rafts, both indicative of growing or changing neuronal connections. Classical and untypical ultrastructural profiles that contained GAP-43 also contained ChAT. We conclude that there is extensive deafness-induced GAP-43-mediated synaptic plasticity in the cochlear nucleus, and that this plasticity is predominantly, if not exclusively, based on cholinergic afferents.
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Affiliation(s)
- Markus A Meidinger
- Neurobiological Research Laboratory, Department of Otorhinolaryngology, University of Freiburg, D-79106 Freiburg, Germany
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179
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Dalva MB, McClelland AC, Kayser MS. Cell adhesion molecules: signalling functions at the synapse. Nat Rev Neurosci 2007; 8:206-20. [PMID: 17299456 PMCID: PMC4756920 DOI: 10.1038/nrn2075] [Citation(s) in RCA: 423] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Many cell adhesion molecules are localized at synaptic sites in neuronal axons and dendrites. These molecules bridge pre- and postsynaptic specializations but do far more than simply provide a mechanical link between cells. In this review, we will discuss the roles these proteins have during development and at mature synapses. Synaptic adhesion proteins participate in the formation, maturation, function and plasticity of synaptic connections. Together with conventional synaptic transmission mechanisms, these molecules are an important element in the trans-cellular communication mediated by synapses.
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Affiliation(s)
- Matthew B Dalva
- University of Pennsylvania Medical Center, Department of Neuroscience, BRB II/III, Room 1114, 421 Curie Blvd., Philadelphia, Pennsylvania 19104, USA.
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180
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Gralle M, Ferreira ST. Structure and functions of the human amyloid precursor protein: the whole is more than the sum of its parts. Prog Neurobiol 2007; 82:11-32. [PMID: 17428603 DOI: 10.1016/j.pneurobio.2007.02.001] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Revised: 10/26/2006] [Accepted: 02/01/2007] [Indexed: 12/30/2022]
Abstract
The amyloid precursor protein (APP) is a transmembrane protein that plays major roles in the regulation of several important cellular functions, especially in the nervous system, where it is involved in synaptogenesis and synaptic plasticity. The secreted extracellular domain of APP, sAPPalpha, acts as a growth factor for many types of cells and promotes neuritogenesis in post-mitotic neurons. Alternative proteolytic processing of APP releases potentially neurotoxic species, including the amyloid-beta (Abeta) peptide that is centrally implicated in the pathogenesis of Alzheimer's disease (AD). Reinforcing this biochemical link to neuronal dysfunction and neurodegeneration, APP is also genetically linked to AD. In this review, we discuss the biological functions of APP in the context of tissue morphogenesis and restructuring, where APP appears to play significant roles both as a contact receptor and as a diffusible factor. Structural investigation of APP, which is necessary for a deeper understanding of its roles at a molecular level, has also been advancing rapidly. We summarize recent progress in the determination of the structure of isolated APP fragments and of the conformations of full-length sAPPalpha, in both monomeric and dimeric states. The potential role of APP dimerization for the regulation of its biological functions is also discussed.
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Affiliation(s)
- Matthias Gralle
- Instituto de Bioquímica Médica, Programa de Bioquímica e Biofísica Celular, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21944-590, Brazil.
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181
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Duveau V, Arthaud S, Rougier A, Le Gal La Salle G. Polysialylation of NCAM is upregulated by hyperthermia and participates in heat shock preconditioning-induced neuroprotection. Neurobiol Dis 2007; 26:385-95. [PMID: 17336079 DOI: 10.1016/j.nbd.2007.01.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 01/16/2007] [Accepted: 01/22/2007] [Indexed: 11/23/2022] Open
Abstract
"Brain tolerance"--a phenomenon in which a subtoxic challenge confers resistance to subsequent brain injuries--provides an ideal opportunity for investigating endogenous neuroprotective mechanisms. We investigated the potential role of the polysialylated (PSA) form of neural cell adhesion molecule (NCAM), which is thought to play a key role in plasticity. In a model where prior exposure to heat shock protects against kainate-induced cell damage in the hippocampus, we show that hyperthermia upregulates PSA-NCAM expression for at least 1 week, without affecting neurogenesis. Pharmacological manipulation of heat shock protein (HSP) expression demonstrates a tight positive link between HSP70 and PSA-NCAM. Finally, the presence of PSA was functionally linked to brain tolerance, as protection against kainate-induced cell death by heat shock pre-exposure was abolished in the absence of NCAM polysialylation. The upregulation of PSA-NCAM by hyperthermia may have a significant impact on hippocampal plasticity, permitting induction of the complex molecular cascade responsible for neuroprotection.
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Affiliation(s)
- V Duveau
- Université Bordeaux 2, CNRS UMR 5227-Mouvement, Adaptation, Cognition, 146, rue Léo Saignat, 33076 Bordeaux Cedex, France
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182
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Markram K, Gerardy-Schahn R, Sandi C. Selective learning and memory impairments in mice deficient for polysialylated NCAM in adulthood. Neuroscience 2007; 144:788-96. [PMID: 17140740 DOI: 10.1016/j.neuroscience.2006.10.024] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 09/08/2006] [Accepted: 10/09/2006] [Indexed: 11/17/2022]
Abstract
The neural cell adhesion molecule (NCAM) has been implicated in regulating synaptic plasticity mechanisms as well as memory consolidation processes. Attachment of polysialic acid to NCAM (PSA-NCAM) has been reported to down-regulate its adhesive forces, a process hypothesized to be implicated in synapse selection after learning experiences. PSA-NCAM has been critically implicated in hippocampus-related synaptic plasticity and memory storage, but information about its functional role in other brain areas remains scarce. Here, we studied mice deficient for polysialyltransferase-1 (ST8SialV/PST-1), an enzyme which attaches PSA to NCAM during postnatal development and adulthood, and whose deficiency results in a drastic reduction of PSA-NCAM expression throughout the brain in adulthood. Mice were tested for their performance in the water maze and auditory fear conditioning (AFC). We report that ST8SiaIV knockout mice were impaired in spatial as well as reversal learning in the water maze. On the other hand, AFC was intact and ST8SiaIV mice exhibited no impairments in the acquisition or retention of cued fear memories. Spatial orientation learning and reversal learning require complex integration of spatial information and response selection involving the hippocampus and prefrontal cortex, whereas cued fear conditioning is an associative type of emotional memory that highly depends on amygdala function. Therefore, our results indicate that PSA-NCAM contributes differentially to learning processes that differ in the nature of the neural computations involved, which probably reflects a differential role of this molecule in different brain regions.
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Affiliation(s)
- K Markram
- Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Station 15, CH-1015 Lausanne, Switzerland
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183
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Abstract
Neural recognition molecules were discovered and characterized initially for their functional roles in cell adhesion as regulators of affinity between cells and the extracellular matrix in vitro. They were then recognized as mediators or co-receptors which trigger signal transduction mechanisms affecting cell adhesion and de-adhesion. Their involvement in contact attraction and repulsion relies on cell-intrinsic properties that are modulated by the spatial contexts of their expression at particular stages of ontogenetic development, in synaptic plasticity and during regeneration after injury. The functional roles of recognition molecules in cell proliferation and migration, determination of developmental fate, growth cone guidance, and synapse formation, stabilization and modulation have been well documented not only by in vitro, but also by in vivo studies that have been greatly aided by generation of genetically altered mice. More recently, the functions of recognition molecules have been investigated under conditions of neural repair and manipulated using a broad range of genetic and pharmacological approaches to achieve a beneficial outcome. The principal aim of most therapeutically oriented approaches has been to neutralize inhibitory factors. However, less attention has been paid to enhancing repair by stimulating the stimulatory factors. When considering potential therapeutic strategies, it is worth considering that a single recognition molecule can possess domains that are conducive or repellent and that the spatial distribution of recognition molecules can determine the overall function: Recognition molecules may be repellent for neurite outgrowth when presented as barriers or steep-concentration gradients and conducive when presented as uniform substrates. The focus of this review will be on the more recent attempts to study the conducive mechanisms with the expectation that they may be able to tip the balance from a regeneration inhospitable to a hospitable environment. It is likely that a combination of the two principles, as multifactorial as each principle may be in itself, will be of therapeutic value in humans.
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Affiliation(s)
- Gabriele Loers
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Universität Hamburg, Hamburg, Germany
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184
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Markram K, Lopez Fernandez MA, Abrous DN, Sandi C. Amygdala upregulation of NCAM polysialylation induced by auditory fear conditioning is not required for memory formation, but plays a role in fear extinction. Neurobiol Learn Mem 2007; 87:573-82. [PMID: 17223582 DOI: 10.1016/j.nlm.2006.11.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2006] [Revised: 11/20/2006] [Accepted: 11/28/2006] [Indexed: 10/23/2022]
Abstract
There is much interest to understand the mechanisms leading to the establishment, maintenance, and extinction of fear memories. The amygdala has been critically involved in the processing of fear memories and a number of molecular changes have been implicated in this brain region in relation to fear learning. Although neural cell adhesion molecules (NCAMs) have been hypothesized to play a role, information available about their contribution to fear memories is scarce. We investigate here whether polysialylated NCAM (PSA-NCAM) contributes to auditory fear conditioning in the amygdala. First, PSA-NCAM expression was evaluated in different amygdala nuclei after auditory fear conditioning at two different shock intensities. Results showed that PSA-NCAM expression was increased 24 h post-training only in animals subjected to the highest shock intensity (1mA). Second, PSA-NCAM was cleaved in the basolateral amygdaloid complex through micro-infusions of the enzyme endoneuraminidase N, and the consequences of such treatment were investigated on the acquisition, consolidation, remote memory expression, and extinction of conditioned fear memories. Intra-amygdaloid cleavage of PSA-NCAM did not affect acquisition, consolidation or expression of remote fear memories. However, intra-amygdaloid PSA-NCAM cleavage enhanced fear extinction processes. These results suggest that upregulation of PSA-NCAM is a correlate of fear conditioning that is not necessary for the establishment of fear memory in the amygdala, but participates in mechanisms precluding fear extinction. These findings point out PSA-NCAM as a potential target for the treatment of psychopathologies that involve impairment in fear extinction.
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Affiliation(s)
- Kamila Markram
- Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Switzerland
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185
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Abstract
The mammalian central nervous system (CNS) requires the proper formation of exquisitely precise circuits to function correctly. These neuronal circuits are assembled during development by the formation of synaptic connections between thousands of differentiating neurons. Proper synapse formation during childhood provides the substrate for cognition, whereas improper formation or function of these synapses leads to neurodevelopmental disorders, including mental retardation and autism. Recent work has begun to identify some of the early cellular events in synapse formation as well as the molecular signals that initiate this process. However, despite the wealth of information published on this topic in the past few years, some of the most fundamental questions about how, whether, and where glutamatergic synapses form in the mammalian CNS remain unanswered. This review focuses on the dynamic aspects of the early cellular and molecular events in the initial assembly of glutamatergic synapses in the mammalian CNS.
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186
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Kato K. Glycobiological Approach to Understanding Neural Plasticity. TRENDS GLYCOSCI GLYC 2007. [DOI: 10.4052/tigg.19.99] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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187
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van der Borght K, Brundin P. Reduced expression of PSA-NCAM in the hippocampus and piriform cortex of the R6/1 and R6/2 mouse models of Huntington's disease. Exp Neurol 2006; 204:473-8. [PMID: 17187781 DOI: 10.1016/j.expneurol.2006.10.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Revised: 10/03/2006] [Accepted: 10/26/2006] [Indexed: 11/26/2022]
Abstract
Cognitive deficits and impaired olfactory function are observed in early stages of Huntington's disease (HD). The polysialylated form of the neural cell adhesion molecule (PSA-NCAM) is strongly associated with plastic events in the brain. During adulthood, it is most abundantly expressed in the hippocampus and the piriform cortex, which are involved in cognition and olfaction, respectively. We show that the numbers of PSA-NCAM-positive cells in the hippocampus and piriform cortex are dramatically reduced in the R6/1 and the R6/2 mouse models of HD. We hypothesize that the decrease in NCAM polysialylation reflects an impaired plasticity and might underlie some of the early symptoms in HD.
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Affiliation(s)
- Karin van der Borght
- Neuronal Survival Unit, Department of Experimental Medical Science, Wallenberg Neuroscience Center, Lund University, BMC A10, 22184 Lund, Sweden.
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188
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Senkov O, Sun M, Weinhold B, Gerardy-Schahn R, Schachner M, Dityatev A. Polysialylated neural cell adhesion molecule is involved in induction of long-term potentiation and memory acquisition and consolidation in a fear-conditioning paradigm. J Neurosci 2006; 26:10888-109898. [PMID: 17050727 PMCID: PMC6674738 DOI: 10.1523/jneurosci.0878-06.2006] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Polysialic acid (PSA) regulates functions of the neural cell adhesion molecule (NCAM) during development and in neuroplasticity in the adult; the underlying mechanisms at different phases of learning and memory consolidation are, however, unknown. To investigate the contributions of PSA versus the extracellular domain of the NCAM glycoprotein backbone to synaptic plasticity, we applied NCAM, PSA-NCAM, and PSA to acute slices of the hippocampal CA1 region of NCAM-deficient mice and measured their effects on long-term potentiation (LTP). Remarkably, only PSA and PSA-NCAM, but not NCAM restored normal LTP. Application of these molecules to the dorsal hippocampus of wild-type mice showed that PSA-NCAM and PSA, but not NCAM, injected before fear conditioning, impaired formation of hippocampus-dependent contextual memory. Consolidation of contextual memory was affected by PSA-NCAM only when injected during its late, but not early phases. None of the tested compounds disturbed extrahippocampal-cued memory. Mice lacking the polysialyltransferase (ST8SialV/PST) responsible for attachment of PSA to NCAM in adulthood showed a mild deficit only in hippocampal contextual learning, when compared with NCAM-deficient mice that were disturbed in both contextual and cued memories. Contextual and tone memory in NCAM-deficient mice could be partially restored by injection of PSA-NCAM, but not of NCAM, into the hippocampus, suggesting that the impact of PSA-NCAM in synaptic plasticity and learning is not mediated by modulation of NCAM-NCAM homophilic interactions. In conclusion, our data support the view that polysialylated NCAM is involved in both formation and late consolidation of contextual memory.
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Affiliation(s)
- Oleg Senkov
- Center for Molecular Neurobiology and
- Institute for Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg, Germany
| | - Mu Sun
- Center for Molecular Neurobiology and
- Department of Physiology, School of Medicine, Jilin University, 130021 Changchun, China, and
| | - Birgit Weinhold
- Department of Cellular Chemistry, Hannover Medical School, D-30625 Hannover, Germany
| | - Rita Gerardy-Schahn
- Department of Cellular Chemistry, Hannover Medical School, D-30625 Hannover, Germany
| | | | - Alexander Dityatev
- Center for Molecular Neurobiology and
- Institute for Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg, Germany
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189
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Hammond MSL, Sims C, Parameshwaran K, Suppiramaniam V, Schachner M, Dityatev A. Neural Cell Adhesion Molecule-associated Polysialic Acid Inhibits NR2B-containing N-Methyl-d-aspartate Receptors and Prevents Glutamate-induced Cell Death. J Biol Chem 2006; 281:34859-69. [PMID: 16987814 DOI: 10.1074/jbc.m602568200] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The neural cell adhesion molecule (NCAM) and its associated glycan polysialic acid play important roles in the development of the nervous system and N-methyl-D-aspartate(NMDA)receptor-dependent synaptic plasticity in the adult. Here, we investigated the influence of polysialic acid on NMDA receptor activity. We found that glutamate-elicited NMDA receptor currents in cultured hippocampal neurons were reduced by approximately 30% with the application of polysialic acid or polysialylated NCAM but not by the sialic acid monomer, chondroitin sulfate, or non-polysialylated NCAM. Polysialic acid inhibited NMDA receptor currents elicited by 3 microm glutamate but not by 30 microm glutamate, suggesting that polysialic acid acts as a competitive antagonist, possibly at the glutamate binding site. The polysialic acid induced effects were mimicked and fully occluded by the NR2B subunit specific antagonist, ifenprodil. Recordings from single synaptosomal NMDA receptors reconstituted in lipid bilayers revealed that polysialic acid reduced open probability but not the conductance of NR2B-containing NMDA receptors in a polysialic acid and glutamate concentration-dependent manner. The activity of single NR2B-lacking synaptosomal NMDA receptors was not affected by polysialic acid. Application of polysialic acid to hippocampal cultures reduced excitotoxic cell death induced by low micromolar concentration of glutamate via activation of NR2B-containing NMDA receptors, whereas enzymatic removal of polysialic acid resulted in increased cell death that occluded glutamate-induced excitotoxicity. These observations indicate that the cell adhesion molecule-associated glycan polysialic acid is able to prevent excitotoxicity via inhibition of NR2B subunit-containing NMDA receptors.
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Affiliation(s)
- Martin S L Hammond
- Zentrum für Molekulare Neurobiologie Hamburg and Institut für Neurophysiologie und Pathophysiologie, Universitätsklinikum Hamburg-Eppendorf, 20246 Hamburg, Germany
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190
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Sytnyk V, Leshchyns'ka I, Nikonenko AG, Schachner M. NCAM promotes assembly and activity-dependent remodeling of the postsynaptic signaling complex. ACTA ACUST UNITED AC 2006; 174:1071-85. [PMID: 17000882 PMCID: PMC2064397 DOI: 10.1083/jcb.200604145] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The neural cell adhesion molecule (NCAM) regulates synapse formation and synaptic strength via mechanisms that have remained unknown. We show that NCAM associates with the postsynaptic spectrin-based scaffold, cross-linking NCAM with the N-methyl-d-aspartate (NMDA) receptor and Ca2+/calmodulin-dependent protein kinase II alpha (CaMKIIalpha) in a manner not firmly or directly linked to PSD95 and alpha-actinin. Clustering of NCAM promotes formation of detergent-insoluble complexes enriched in postsynaptic proteins and resembling postsynaptic densities. Disruption of the NCAM-spectrin complex decreases the size of postsynaptic densities and reduces synaptic targeting of NCAM-spectrin-associated postsynaptic proteins, including spectrin, NMDA receptors, and CaMKIIalpha. Degeneration of the spectrin scaffold in NCAM-deficient neurons results in an inability to recruit CaMKIIalpha to synapses after NMDA receptor activation, which is a critical process in NMDA receptor-dependent long-term potentiation. The combined observations indicate that NCAM promotes assembly of the spectrin-based postsynaptic signaling complex, which is required for activity-associated, long-lasting changes in synaptic strength. Its abnormal function may contribute to the etiology of neuropsychiatric disorders associated with mutations in or abnormal expression of NCAM.
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Affiliation(s)
- Vladimir Sytnyk
- Zentrum für Molekulare Neurobiologie, Universität Hamburg, 20246 Hamburg, Germany
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191
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Sairanen M, O'Leary OF, Knuuttila JE, Castrén E. Chronic antidepressant treatment selectively increases expression of plasticity-related proteins in the hippocampus and medial prefrontal cortex of the rat. Neuroscience 2006; 144:368-74. [PMID: 17049169 DOI: 10.1016/j.neuroscience.2006.08.069] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 08/16/2006] [Accepted: 08/31/2006] [Indexed: 02/07/2023]
Abstract
Antidepressants protect against hippocampal volume loss in humans and reverse stress-induced atrophic changes in animals thus supporting the hypothesis that the pathophysiology of stress-related disorders such as depression involves reductions in neuronal connectivity and this effect is reversible by antidepressant treatment. However, it is unclear which brain areas demonstrate such alterations in plasticity in response to antidepressant treatment. The aim of the present study was to examine the effect of antidepressant treatment on the expression of three plasticity-associated marker proteins, the polysialylated form of nerve cell adhesion molecule (PSA-NCAM), phosphorylated cyclic-AMP response element binding protein (pCREB) and growth-associated protein 43 (GAP-43), in the rat brain. To this end, rats were treated either acutely (60 min) or chronically (21 days) with imipramine (30 and 15 mg/kg, respectively) and the expression of PSA-NCAM, pCREB, and GAP-43 was assessed using immunohistochemistry. Initial mapping revealed that chronic imipramine treatment increased expression of these plasticity-associated proteins in the hippocampus, medial prefrontal cortex and piriform cortex but not in the other brain regions examined. Since PSA-NCAM and pCREB are expressed in recently-generated neurons in the dentate gyrus, it is likely that chronic imipramine treatment increased their expression in the hippocampus at least partially by increasing neurogenesis. In contrast, since chronic imipramine treatment is not associated with neurogenesis in the medial prefrontal cortex, increased expression of PSA-NCAM and pCREB in the prelimbic cortex implicates changes in synaptic connectivity in this brain region. Acute treatment with imipramine increased the number of pCREB positive nuclei in the hippocampus and the prefrontal cortex but did not alter expression of GAP-43 or PSA-NCAM in any of the brain regions examined. Taken together, the results of the present study suggest that antidepressant treatment increases synaptic plasticity and connectivity in brain regions associated with mood disorders.
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Affiliation(s)
- M Sairanen
- Sigrid Jusélius Laboratory, Neuroscience Center, University of Helsinki, P.O. Box 56, 00014 University of Helsinki, Helsinki, Finland
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192
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Stoenica L, Senkov O, Gerardy-Schahn R, Weinhold B, Schachner M, Dityatev A. In vivo synaptic plasticity in the dentate gyrus of mice deficient in the neural cell adhesion molecule NCAM or its polysialic acid. Eur J Neurosci 2006; 23:2255-64. [PMID: 16706834 DOI: 10.1111/j.1460-9568.2006.04771.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The neural cell adhesion molecule NCAM and its associated polysialic acid (PSA) play important roles in synaptic plasticity in the CA1 and/or CA3 regions of the hippocampus in vitro. Here, we address the question of whether NCAM and PSA are involved in regulation of synaptic transmission and plasticity also in vivo at synapses formed by entorhinal cortex axons in the dentate gyrus of mice anaesthetized with urethane. We show that basal synaptic transmission, measured as the slope of field excitatory postsynaptic potentials, was reduced strongly in mice lacking ST8SiaII/STX, the enzyme involved in polysialylation of NCAM in stem cell-derived immature granule cells, but not in mice deficient either in the NCAM glycoprotein or the enzyme ST8SiaIV/PST involved in polysialylation of NCAM in mature neurons. Strikingly, only mice deficient in NCAM, but not in PST or STX, were impaired in long-term potentiation (LTP) induced by theta-burst stimulation, suggesting that LTP in the dentate gyrus depends on the NCAM glycoprotein alone rather than on its associated PSA. As also patterns of synaptic activity during and immediately after induction of LTP were impaired in NCAM-deficient mice, it is likely that induction of LTP requires NCAM. These data are the first to describe that NCAM is necessary for induction of synaptic plasticity in identified synapses in vivo and suggest that polysialylation of NCAM expressed by immature granule cells in the dentate gyrus supports development of basal excitatory synaptic transmission in this region.
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Affiliation(s)
- Luminita Stoenica
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Martinistr. 52, D-20246 Hamburg, Germany
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193
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Bonfanti L. PSA-NCAM in mammalian structural plasticity and neurogenesis. Prog Neurobiol 2006; 80:129-64. [PMID: 17029752 DOI: 10.1016/j.pneurobio.2006.08.003] [Citation(s) in RCA: 336] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 08/04/2006] [Accepted: 08/21/2006] [Indexed: 12/14/2022]
Abstract
Polysialic acid (PSA) is a linear homopolymer of alpha2-8-N acetylneuraminic acid whose major carrier in vertebrates is the neural cell adhesion molecule (NCAM). PSA serves as a potent negative regulator of cell interactions via its unusual biophysical properties. PSA on NCAM is developmentally regulated thus playing a prominent role in different forms of neural plasticity spanning from embryonic to adult nervous system, including axonal growth, outgrowth and fasciculation, cell migration, synaptic plasticity, activity-induced plasticity, neuronal-glial plasticity, embryonic and adult neurogenesis. The cellular distribution, developmental changes and possible function(s) of PSA-NCAM in the central nervous system of mammals here are reviewed, along with recent findings and theories about the relationships between NCAM protein and PSA as well as the role of different polysialyltransferases. Particular attention is focused on postnatal/adult neurogenesis, an issue which has been deeply investigated in the last decade as an example of persisting structural plasticity with potential implications for brain repair strategies. Adult neurogenic sites, although harbouring all subsequent steps of cell differentiation, from stem cell division to cell replacement, do not faithfully recapitulate development. After birth, they undergo morphological and molecular modifications allowing structural plasticity to adapt to the non-permissive environment of the mature nervous tissue, that are paralled by changes in the expression of PSA-NCAM. The use of PSA-NCAM as a marker for exploring differences in structural plasticity and neurogenesis among mammalian species is also discussed.
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Affiliation(s)
- Luca Bonfanti
- Department of Veterinary Morphophysiology, University of Turin, Via Leonardo da Vinci 44, 10095 Grugliasco, Italy.
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194
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Polysialic Acid Profiles of Mice Expressing Variant Allelic Combinations of the Polysialyltransferases ST8SiaII and ST8SiaIV. J Biol Chem 2006. [DOI: 10.1016/s0021-9258(19)84074-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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195
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Ferri P, Cecchini T, Ambrogini P, Betti M, Cuppini R, Del Grande P, Ciaroni S. alpha-Tocopherol affects neuronal plasticity in adult rat dentate gyrus: the possible role of PKCdelta. ACTA ACUST UNITED AC 2006; 66:793-810. [PMID: 16673395 DOI: 10.1002/neu.20255] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Hippocampus dentate gyrus (DG) is characterized by neuronal plasticity processes in adulthood, and polysialylation of NCAM promotes neuronal plasticity. In previous investigations we found that alpha-tocopherol increased the PSA-NCAM-positive granule cell number in adult rat DG, suggesting that alpha-tocopherol may enhance neuronal plasticity. To verify this hypothesis, in the present study, structural remodeling in adult rat DG was investigated under alpha-tocopherol supplementation conditions. PSA-NCAM expression was evaluated by Western blotting, evaluation of PSA-NCAM-positive granule cell density, and morphometric analysis of PSA-NCAM-positive processes. In addition, the optical density of synaptophysin immunoreactivity and the synaptic profile density, examined by electron microscopy, were evaluated. Moreover, considering that PSA-NCAM expression has been found to be related to PKCdelta activity and alpha-tocopherol has been shown to inhibit PKC activity in vitro, Western blotting and immunohistochemistry followed by densitometry were used to analyze PKC. Our results demonstrated that an increase in PSA-NCAM expression and optical density of DG molecular layer synaptophysin immunoreactivity occurred in alpha-tocopherol-treated rats. Electron microscopy analysis showed that the increase in synaptophysin expression was related to an increase in synaptic profile density. In addition, Western blotting revealed a decrease in phospho-PKC Pan and phospho-PKCdelta, demonstrating that alpha-tocopherol is also able to inhibit PKC activity in vivo. Likewise, immunoreactivity for the active form of PKCdelta was lower in alpha-tocopherol-treated rats than in controls, while no changes were found in PKCdelta expression. These results demonstrate that alpha-tocopherol is an exogenous factor affecting neuronal plasticity in adult rat DG, possibly through PKCdelta inhibition.
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Affiliation(s)
- Paola Ferri
- Institute of Morphological Sciences, University of Urbino Carlo Bo, Italy.
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196
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Galuska SP, Oltmann-Norden I, Geyer H, Weinhold B, Kuchelmeister K, Hildebrandt H, Gerardy-Schahn R, Geyer R, Mühlenhoff M. Polysialic acid profiles of mice expressing variant allelic combinations of the polysialyltransferases ST8SiaII and ST8SiaIV. J Biol Chem 2006; 281:31605-15. [PMID: 16940046 DOI: 10.1074/jbc.m606516200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The post-translational modification of the neural cell adhesion molecule (NCAM) by polysialic acid (polySia) represents a remarkable example of dynamic modulation of homo- and heterophilic cell interactions by glycosylation. The synthesis of this unique carbohydrate polymer depends on the polysialyltransferases ST8SiaII and ST8SiaIV. Aiming to understand in more detail the contributions of ST8SiaII and ST8SiaIV to polySia biosynthesis in vivo, we used mutant mouse lines that differ in the number of functional polysialyltransferase alleles. The 1,2-diamino-4,5-methylenedioxybenzene method was used to qualitatively and quantitatively assess the polySia patterns. Similar to the wild-type genotype, long polySia chains (>50 residues) were detected in all genotypes expressing at least one functional polysialyltransferase allele. However, variant allelic combinations resulted in distinct alterations in the total amount of poly-Sia; the relative abundance of long, medium, and short polymers; and the ratio of polysialylated to non-polysialylated NCAM. In ST8SiaII-null mice, 45% of the brain NCAM was non-polysialylated, whereas a single functional allele of ST8SiaII was sufficient to polysialylate approximately 90% of the NCAM pool. Our data reveal a complex polysialylation pattern and show that, under in vivo conditions, the coordinated action of ST8SiaII and ST8SiaIV is crucial to fine-tune the amount and structure of polySia on NCAM.
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Affiliation(s)
- Sebastian P Galuska
- Institute of Biochemistry, Faculty of Medicine, University of Giessen, D-35392 Giessen, Germany
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197
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Brocco MA, Frasch ACC. Interfering polysialyltransferase ST8SiaII/STX mRNA inhibits neurite growth during early hippocampal development. FEBS Lett 2006; 580:4723-6. [PMID: 16887122 DOI: 10.1016/j.febslet.2006.07.058] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Revised: 07/11/2006] [Accepted: 07/18/2006] [Indexed: 10/24/2022]
Abstract
Polysialic acid (PSA) attached to NCAM is involved in cell-cell interactions participating in structural and functional plasticity of neuronal circuits. Two polysialyltransferases, ST8SiaII/STX and ST8SiaIV/PST, polysialylate NCAM. We previously suggested that ST8SiaII/STX is the key enzyme for polysialylation in hippocampus. Here, polysialyltransferase mRNA interference experiments showed that, knock down of ST8SiaIV/PST transcripts did not affect PSA expression, but PSA was almost absent from neuronal surfaces when ST8SiaII/STX mRNA was interfered. Non-polysialylated neurons bore a similar number of neurites per cell than polysialylated neurons. However, non-polysialylated processes were shorter and a lower density of synaptophysin clusters accompanied this reduced neuritic growth. Therefore, ST8SiaII/STX expression is essential to allow a correct neuritic development at initial stages of hippocampus ontogeny.
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Affiliation(s)
- Marcela A Brocco
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús-Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de General San Martín, Buenos Aires, Argentina.
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198
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Piechotta K, Dudanova I, Missler M. The resilient synapse: insights from genetic interference of synaptic cell adhesion molecules. Cell Tissue Res 2006; 326:617-42. [PMID: 16855838 DOI: 10.1007/s00441-006-0267-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Accepted: 05/31/2006] [Indexed: 01/05/2023]
Abstract
Synaptic cell adhesion molecules (SCAMs) are mostly membrane-anchored molecules with extracellular domains that extend into the synaptic cleft. Prototypical SCAMs interact with homologous or heterologous molecules on the surface of adjacent cells, ensuring the precise apposition of pre- and postsynaptic elements. More recent definitions of SCAMs often include molecules involved in axon pathfinding, cell recognition and synaptic differentiation events, making SCAMs functionally and molecularly a highly diverse group. In this review, we summarize the proposed in vivo functions of a large variety of SCAMs. We mainly focus on results obtained from analyses of genetic model organisms, mostly mouse knockout mutants, lacking expression of the respective candidate genes. In contrast to the substantial effect yielded by some knockouts of molecules involved in synaptic vesicle release, no SCAM mutant has been reported thus far that shows a prominently altered structure of the majority of synapses or even lacks synapses altogether. This surprising resilience of synaptic structure might be explained by a high redundancy between different SCAMs, by the assumption that the crucial molecular players in synapse structure have yet to be discovered or by a grand variability in the mechanisms of synapse formation that underlies the diversity of synapses. Whatever the final answer turns out to be, the genetic dissection of the SCAM superfamilies has led to a much better understanding of the different steps required to form, differentiate and modify a synapse.
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Affiliation(s)
- Kerstin Piechotta
- Center for Physiology and Pathophysiology, Georg-August University, Humboldtallee 23, 37073 Göttingen, Germany
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199
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Dityatev A, Frischknecht R, Seidenbecher CI. Extracellular matrix and synaptic functions. Results Probl Cell Differ 2006; 43:69-97. [PMID: 17068968 DOI: 10.1007/400_025] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Comprehensive analysis of neuromuscular junction formation and recent data on synaptogenesis and long-term potentiation in the central nervous system revealed a number of extracellular matrix (ECM) molecules regulating different aspects of synaptic differentiation and function. The emerging mechanisms comprise interactions of ECM components with their cell surface receptors coupled to tyrosine kinase activities (agrin, integrin ligands, and reelin) and interactions with ion channels and transmitter receptors (Narp, tenascin-R and tenascin-C). These interactions may shape synaptic transmission and plasticity of excitatory synapses either via regulation of Ca2+ entry and postsynaptic expression of transmitter receptors or via control of GABAergic inhibition. The ECM molecules, derived from both neurons and glial cells and secreted into the extracellular space in an activity-dependent manner, may also shape synaptic plasticity through setting diffusion constraints for neurotransmitters, trophic factors and ions.
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Affiliation(s)
- Alexander Dityatev
- Institut für Neurophysiologie und Pathophysiologie, Universitätsklinikum Hamburg-Eppendorf, Germany.
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200
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Dityatev A, Schachner M. The extracellular matrix and synapses. Cell Tissue Res 2006; 326:647-54. [PMID: 16767406 DOI: 10.1007/s00441-006-0217-1] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Accepted: 04/20/2006] [Indexed: 11/27/2022]
Abstract
Extracellular matrix (ECM) molecules, derived from both neurons and glial cells, are secreted and accumulate in the extracellular space to regulate various aspects of pre- and postsynaptic differentiation, the maturation of synapses, and their plasticity. The emerging mechanisms comprise interactions of agrin, integrin ligands, and reelin, with their cognate cell-surface receptors being coupled to tyrosine kinase activities. These may induce the clustering of postsynaptic receptors and changes in their composition and function. Furthermore, direct interactions of laminins, neuronal pentraxins, and tenascin-R with voltage-gated Ca(2+) channels, alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA), and gamma-aminobutyric acid(B) (GABA(B)) receptors, respectively, shape the organization and function of different subsets of synapses. Some of these mechanisms significantly contribute to the induction of long-term potentiation in excitatory synapses, either by the regulation of Ca(2+) entry via N-methyl-D-aspartate receptors or L-type Ca(2+) channels, or by the control of GABAergic inhibition.
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Affiliation(s)
- Alexander Dityatev
- Institut für Neurophysiologie und Pathophysiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
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