51
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Karasawa T, Lombroso PJ. Disruption of striatal-enriched protein tyrosine phosphatase (STEP) function in neuropsychiatric disorders. Neurosci Res 2014; 89:1-9. [PMID: 25218562 DOI: 10.1016/j.neures.2014.08.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 08/12/2014] [Accepted: 08/21/2014] [Indexed: 10/24/2022]
Abstract
Striatal-enriched protein tyrosine phosphatase (STEP) is a brain-specific tyrosine phosphatase that plays a major role in the development of synaptic plasticity. Recent findings have implicated STEP in several psychiatric and neurological disorders, including Alzheimer's disease, schizophrenia, fragile X syndrome, Huntington's disease, stroke/ischemia, and stress-related psychiatric disorders. In these disorders, STEP protein expression levels and activity are dysregulated, contributing to the cognitive deficits that are present. In this review, we focus on the most recent findings on STEP, discuss how STEP expression and activity are maintained during normal cognitive function, and how disruptions in STEP activity contribute to a number of illnesses.
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Affiliation(s)
- Takatoshi Karasawa
- Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi 480-0392, Japan.
| | - Paul J Lombroso
- Departments of Neurobiology, Psychiatry and Child Study Center, Yale University School of Medicine, New Haven, CT 06520, USA
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52
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Kuwabara Y, Ishizeki M, Watamura N, Toba J, Yoshii A, Inoue T, Ohshima T. Impairments of long-term depression induction and motor coordination precede Aβ accumulation in the cerebellum of APPswe/PS1dE9 double transgenic mice. J Neurochem 2014; 130:432-43. [DOI: 10.1111/jnc.12728] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 03/23/2014] [Accepted: 03/27/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Yuki Kuwabara
- Laboratory for Molecular Brain Science; Department of Life Science and Medical Bioscience; Waseda University; Tokyo Japan
| | - Masato Ishizeki
- Laboratory of Neurophysiology; Department of Life Science and Medical Bioscience; Waseda University; Tokyo Japan
| | - Naoto Watamura
- Laboratory for Molecular Brain Science; Department of Life Science and Medical Bioscience; Waseda University; Tokyo Japan
| | - Junya Toba
- Laboratory for Molecular Brain Science; Department of Life Science and Medical Bioscience; Waseda University; Tokyo Japan
| | - Aya Yoshii
- Laboratory for Molecular Brain Science; Department of Life Science and Medical Bioscience; Waseda University; Tokyo Japan
| | - Takafumi Inoue
- Laboratory of Neurophysiology; Department of Life Science and Medical Bioscience; Waseda University; Tokyo Japan
| | - Toshio Ohshima
- Laboratory for Molecular Brain Science; Department of Life Science and Medical Bioscience; Waseda University; Tokyo Japan
- Laboratory for Developmental Neurobiology; RIKEN Brain Science Institute; Wako Saitama Japan
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53
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Puzzo D, Lee L, Palmeri A, Calabrese G, Arancio O. Behavioral assays with mouse models of Alzheimer's disease: practical considerations and guidelines. Biochem Pharmacol 2014; 88:450-67. [PMID: 24462904 PMCID: PMC4014001 DOI: 10.1016/j.bcp.2014.01.011] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 01/09/2014] [Accepted: 01/09/2014] [Indexed: 12/14/2022]
Abstract
In Alzheimer's disease (AD) basic research and drug discovery, mouse models are essential resources for uncovering biological mechanisms, validating molecular targets and screening potential compounds. Both transgenic and non-genetically modified mouse models enable access to different types of AD-like pathology in vivo. Although there is a wealth of genetic and biochemical studies on proposed AD pathogenic pathways, as a disease that centrally features cognitive failure, the ultimate readout for any interventions should be measures of learning and memory. This is particularly important given the lack of knowledge on disease etiology - assessment by cognitive assays offers the advantage of targeting relevant memory systems without requiring assumptions about pathogenesis. A multitude of behavioral assays are available for assessing cognitive functioning in mouse models, including ones specific for hippocampal-dependent learning and memory. Here we review the basics of available transgenic and non-transgenic AD mouse models and detail three well-established behavioral tasks commonly used for testing hippocampal-dependent cognition in mice - contextual fear conditioning, radial arm water maze and Morris water maze. In particular, we discuss the practical considerations, requirements and caveats of these behavioral testing paradigms.
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Affiliation(s)
- Daniela Puzzo
- Department of Bio-Medical Sciences - Section of Physiology, University of Catania, Viale A. Doria 6, Catania 95125, Italy
| | - Linda Lee
- Department of Pathology & Cell Biology, The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, P&S #12-420D, 630W 168th Street, New York, NY 10032, USA
| | - Agostino Palmeri
- Department of Bio-Medical Sciences - Section of Physiology, University of Catania, Viale A. Doria 6, Catania 95125, Italy
| | - Giorgio Calabrese
- Department of Pharmacy, Federico II University, Via D. Montesano 49, Naples 80131, Italy
| | - Ottavio Arancio
- Department of Pathology & Cell Biology, The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, P&S #12-420D, 630W 168th Street, New York, NY 10032, USA.
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54
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Dendritic integration in pyramidal neurons during network activity and disease. Brain Res Bull 2014; 103:2-10. [DOI: 10.1016/j.brainresbull.2013.09.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 09/18/2013] [Accepted: 09/19/2013] [Indexed: 11/18/2022]
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55
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Hu NW, Nicoll AJ, Zhang D, Mably AJ, O'Malley T, Purro SA, Terry C, Collinge J, Walsh DM, Rowan MJ. mGlu5 receptors and cellular prion protein mediate amyloid-β-facilitated synaptic long-term depression in vivo. Nat Commun 2014; 5:3374. [PMID: 24594908 PMCID: PMC4354159 DOI: 10.1038/ncomms4374] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 02/04/2014] [Indexed: 11/12/2022] Open
Abstract
NMDA-type glutamate receptors (NMDARs) are currently regarded as paramount in the
potent and selective disruption of synaptic plasticity by Alzheimer’s
disease amyloid β-protein
(Aβ). Non-NMDAR
mechanisms remain relatively unexplored. Here we describe how Aβ facilitates NMDAR-independent
long-term depression of synaptic transmission in the hippocampus in vivo.
Synthetic Aβ and
Aβ in soluble
extracts of Alzheimer’s disease brain usurp endogenous acetylcholine
muscarinic receptor-dependent long-term depression, to enable long-term depression
that required metabotropic glutamate-5
receptors (mGlu5Rs). We also find that mGlu5Rs are essential for Aβ-mediated inhibition of NMDAR-dependent long-term
potentiation in vivo. Blocking Aβ binding to cellular prion protein with antibodies prevents the facilitation
of long-term depression. Our findings uncover an overarching role for Aβ-PrPC-mGlu5R interplay in mediating both LTD
facilitation and LTP inhibition, encompassing NMDAR-mediated processes that were
previously considered primary. In Alzheimer's disease, the soluble amyloid beta peptide is
known to modulate synaptic function by forming a complex with prion proteins and
metabotropic glutamate receptors. Here, Hu et al. show that amyloid beta
signalling via this complex facilitates the induction of long-term depression at
synapses.
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Affiliation(s)
- Neng-Wei Hu
- Department of Pharmacology and Therapeutics, and Trinity College Institute of Neuroscience, Biotechnology Building, Trinity College Dublin, Dublin 2, Ireland
| | - Andrew J Nicoll
- Medical Research Council Prion Unit and Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Dainan Zhang
- Department of Pharmacology and Therapeutics, and Trinity College Institute of Neuroscience, Biotechnology Building, Trinity College Dublin, Dublin 2, Ireland
| | - Alexandra J Mably
- Laboratory for Neurodegenerative Research, Center for Neurologic Diseases, Brigham & Women's Hospital, Harvard Institute of Medicine, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA
| | - Tiernan O'Malley
- Laboratory for Neurodegenerative Research, Center for Neurologic Diseases, Brigham & Women's Hospital, Harvard Institute of Medicine, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA
| | - Silvia A Purro
- Medical Research Council Prion Unit and Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Cassandra Terry
- Medical Research Council Prion Unit and Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - John Collinge
- Medical Research Council Prion Unit and Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Dominic M Walsh
- Laboratory for Neurodegenerative Research, Center for Neurologic Diseases, Brigham & Women's Hospital, Harvard Institute of Medicine, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA
| | - Michael J Rowan
- Department of Pharmacology and Therapeutics, and Trinity College Institute of Neuroscience, Biotechnology Building, Trinity College Dublin, Dublin 2, Ireland
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56
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Cheng D, Low JK, Logge W, Garner B, Karl T. Novel behavioural characteristics of female APPSwe/PS1ΔE9 double transgenic mice. Behav Brain Res 2014; 260:111-8. [DOI: 10.1016/j.bbr.2013.11.046] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 11/19/2013] [Accepted: 11/25/2013] [Indexed: 02/06/2023]
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Bolognin S, Lorenzetto E, Diana G, Buffelli M. The potential role of rho GTPases in Alzheimer's disease pathogenesis. Mol Neurobiol 2014; 50:406-22. [PMID: 24452387 DOI: 10.1007/s12035-014-8637-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 01/02/2014] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is characterized by a wide loss of synapses and dendritic spines. Despite extensive efforts, the molecular mechanisms driving this detrimental alteration have not yet been determined. Among the factors potentially mediating this loss of neuronal connectivity, the contribution of Rho GTPases is of particular interest. This family of proteins is classically considered a key regulator of actin cytoskeleton remodeling and dendritic spine maintenance, but new insights into the complex dynamics of its regulation have recently determined how its signaling cascade is still largely unknown, both in physiological and pathological conditions. Here, we review the growing evidence supporting the potential involvement of Rho GTPases in spine loss, which is a unanimously recognized hallmark of early AD pathogenesis. We also discuss some new insights into Rho GTPase signaling framework that might explain several controversial results that have been published. The study of the connection between AD and Rho GTPases represents a quite unchartered avenue that holds therapeutic potential.
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Affiliation(s)
- Silvia Bolognin
- Department of Neurological and Movement Sciences, Section of Physiology, University of Verona, Strada le Grazie 8, 37134, Verona, Italy,
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58
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Camboni M, Wang CM, Miranda C, Yoon JH, Xu R, Zygmunt D, Kaspar BK, Martin PT. Active and passive immunization strategies based on the SDPM1 peptide demonstrate pre-clinical efficacy in the APPswePSEN1dE9 mouse model for Alzheimer's disease. Neurobiol Dis 2013; 62:31-43. [PMID: 24021662 DOI: 10.1016/j.nbd.2013.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 07/18/2013] [Accepted: 09/01/2013] [Indexed: 12/31/2022] Open
Abstract
Recent clinical and pre-clinical studies suggest that both active and passive immunization strategies targeting Aβ amyloid may have clinical benefit in Alzheimer's disease. Here, we demonstrate that vaccination of APPswePSEN1dE9 mice with SDPM1, an engineered non-native Aβ amyloid-specific binding peptide, lowers brain Aβ amyloid plaque burden and brain Aβ1-40 and Aβ1-42 peptide levels, improves cognitive learning and memory in Morris water maze tests and increases the expression of synaptic brain proteins. This was the case in young mice immunized prior to development of significant brain amyloid burden, and in older mice, where brain amyloid was already present. Active immunization was optimized using ALUM as an adjuvant to stimulate production of anti-SDPM1 and anti-Aβ amyloid antibodies. Intracerebral injection of P4D6, an SDPM1 peptide-mimotope antibody, also lowered brain amyloid plaque burden in APPswePSEN1dE9 mice. Additionally, P4D6 inhibited Aβ amyloid-mediated toxicity in cultured neuronal cells. The protein sequence of the variable domain within the P4D6 heavy chain was found to mimic a multimer of the SDPM1 peptide motif. These data demonstrate the efficacy of active and passive vaccine strategies to target Aβ amyloid oligomers using an engineered peptide-mimotope strategy.
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Affiliation(s)
- Marybeth Camboni
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, USA
| | - Chiou-Miin Wang
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, USA
| | - Carlos Miranda
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, USA
| | - Jung Hae Yoon
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, USA
| | - Rui Xu
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, USA
| | - Deborah Zygmunt
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, USA
| | - Brian K Kaspar
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, USA; Department of Pediatrics, The Ohio State University, USA; Department of Neuroscience, The Ohio State University, USA
| | - Paul T Martin
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, USA; Department of Pediatrics, The Ohio State University, USA; Department of Physiology and Cell Biology, The Ohio State University, USA.
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59
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Chen X, Lin R, Chang L, Xu S, Wei X, Zhang J, Wang C, Anwyl R, Wang Q. Enhancement of long-term depression by soluble amyloid β protein in rat hippocampus is mediated by metabotropic glutamate receptor and involves activation of p38MAPK, STEP and caspase-3. Neuroscience 2013; 253:435-43. [PMID: 24012839 DOI: 10.1016/j.neuroscience.2013.08.054] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 08/20/2013] [Accepted: 08/27/2013] [Indexed: 10/26/2022]
Abstract
It is reported that the amyloid-β protein (Aβ)-induced impairments in synaptic plasticity coincide with memory decline and dementia. Although Aβ-induced inhibition of hippocampal long-term potentiation has been intensively investigated, the underlying mechanism of Aβ-enhanced long-term depression (LTD) is not clear. Here, we report that acute exposure of rat hippocampal slices to soluble Aβ-enhanced LTD induced by weak low-frequency stimulation (wLFS; 1Hz for 3 min, 180 pulses) in granule cells of the dentate gyrus. Application of LY341495 (a non-selective Group I/II metrabotropic glumate receptor (mGluR) antagonist) completely blocked Aβ-enhanced LTD, whereas D-AP5 (a not selective N-methyl-d-aspartate receptor (NMDAR) antagonist) had no effect on Aβ-enhanced LTD compared with controls. In addition, Aβ-enhanced LTD was occluded by pre-application of 3,5-dihydroxyphenylglycine, a Group1 mGluR (mGluR1/5) agonist, suggesting Aβ-enhanced LTD depends on mGluR1/5 but not NMDAR. We also report here that p38 mitogen-activated protein kinase (p38MAPK) inhibitor SB203580 and postsynaptic protein tyrosine phosphatase inhibitors phenylarsine oxide and sodium orthovanadate prevented the facilitatory effect of Aβ on LTD. Application of striatal-enriched protein tyrosine phosphatase (STEP) activator MG132 facilitated induction of LTD by wLFS, but did not block following Aβ-enhanced LTD induced by another wLFS. On the other hand, Aβ-enhanced LTD blocked following MG132-LTD by wLFS, suggesting Aβ-enhanced hippocampal LTD involves STEP activation. Application of either non-selective caspase inhibitor Z-VAD-FMK or caspase-3 selective inhibitor Z-DEVD-FMK prevented Aβ-enhanced LTD. However, neither the tumor necrosis factor-α converting enzyme inhibitor TAPI-2 nor the mammalian target of rapamycin inhibitor rapamycin prevented the enhancement of Aβ on LTD. Therefore, we conclude that soluble Aβ enhances LTD in the hippocampal dentate gyrus region, and the facilitatory effect of Aβ on LTD involves mGluR1/5, p38MAPK, STEP and caspase-3 activation.
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Affiliation(s)
- X Chen
- Department of Physiology, Medical School, Research Center of Behavioral Science, Ningbo University, Ningbo 315211, China
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60
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Daulatzai MA. Neurotoxic Saboteurs: Straws that Break the Hippo’s (Hippocampus) Back Drive Cognitive Impairment and Alzheimer’s Disease. Neurotox Res 2013; 24:407-59. [DOI: 10.1007/s12640-013-9407-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 06/06/2013] [Accepted: 06/17/2013] [Indexed: 12/29/2022]
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61
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Tamburri A, Dudilot A, Licea S, Bourgeois C, Boehm J. NMDA-receptor activation but not ion flux is required for amyloid-beta induced synaptic depression. PLoS One 2013; 8:e65350. [PMID: 23750255 PMCID: PMC3672194 DOI: 10.1371/journal.pone.0065350] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Accepted: 04/25/2013] [Indexed: 01/31/2023] Open
Abstract
Alzheimer disease is characterized by a gradual decrease of synaptic function and, ultimately, by neuronal loss. There is considerable evidence supporting the involvement of oligomeric amyloid-beta (Aβ) in the etiology of Alzheimer’s disease. Historically, AD research has mainly focused on the long-term changes caused by Aβ rather than analyzing its immediate effects. Here we show that acute perfusion of hippocampal slice cultures with oligomeric Aβ depresses synaptic transmission within 20 minutes. This depression is dependent on synaptic stimulation and the activation of NMDA-receptors, but not on NMDA-receptor mediated ion flux. It, therefore, appears that Aβ dependent synaptic depression is mediated through a use-dependent metabotropic-like mechanism of the NMDA-receptor, but does not involve NMDA-receptor mediated synaptic transmission, i.e. it is independent of calcium flux through the NMDA-receptor.
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Affiliation(s)
- Albert Tamburri
- Département de Physiologie, Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
| | - Anthony Dudilot
- Département de Physiologie, Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
| | - Sara Licea
- Département de Physiologie, Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
| | - Catherine Bourgeois
- Département de Physiologie, Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
| | - Jannic Boehm
- Département de Physiologie, Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
- * E-mail:
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62
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Danysz W, Parsons CG. Alzheimer's disease, β-amyloid, glutamate, NMDA receptors and memantine--searching for the connections. Br J Pharmacol 2013; 167:324-52. [PMID: 22646481 DOI: 10.1111/j.1476-5381.2012.02057.x] [Citation(s) in RCA: 335] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
β-amyloid (Aβ) is widely accepted to be one of the major pathomechanisms underlying Alzheimer's disease (AD), although there is presently lively debate regarding the relative roles of particular species/forms of this peptide. Most recent evidence indicates that soluble oligomers rather than plaques are the major cause of synaptic dysfunction and ultimately neurodegeneration. Soluble oligomeric Aβ has been shown to interact with several proteins, for example glutamatergic receptors of the NMDA type and proteins responsible for maintaining glutamate homeostasis such as uptake and release. As NMDA receptors are critically involved in neuronal plasticity including learning and memory, we felt that it would be valuable to provide an up to date review of the evidence connecting Aβ to these receptors and related neuronal plasticity. Strong support for the clinical relevance of such interactions is provided by the NMDA receptor antagonist memantine. This substance is the only NMDA receptor antagonist used clinically in the treatment of AD and therefore offers an excellent tool to facilitate translational extrapolations from in vitro studies through in vivo animal experiments to its ultimate clinical utility.
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Affiliation(s)
- Wojciech Danysz
- Merz Pharmaceuticals GmbH, Eckenheimer Landstraße, Frankfurt am Main, Germany
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63
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Age-dependent alterations in the presynaptic active zone in a Drosophila model of Alzheimer's disease. Neurobiol Dis 2012; 51:161-7. [PMID: 23149068 DOI: 10.1016/j.nbd.2012.11.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 10/08/2012] [Accepted: 11/02/2012] [Indexed: 11/23/2022] Open
Abstract
The accumulation of beta amyloid (Aβ) can cause synaptic impairments, but the characteristics and mechanisms of the synaptic impairment induced by the accumulation of Aβ in Alzheimer's disease (AD) remain unclear. In identified single neurons in a newly developed Drosophila AD model, in which Aβ accumulates intraneuronally, we found an age-dependent reduction in the synaptic vesicle release probability that was associated with a decrease in the density of presynaptic calcium channel clusters and an increase in the presynaptic and postsynaptic contact length. Moreover, these alterations occurred in the absence of presynaptic bouton loss. In addition, we found that Aβ expression also produced an age-dependent decrease in the amount of Bruchpilot (Brp), which plays an important role in controlling Ca(2+) channel clustering and synaptic vesicle release in the presynaptic active zone. Our study indicates that the chronic accumulation of intraneuronal Aβ can induce functional and structural changes in the presynaptic active zone prior to a loss of presynaptic buttons in the same neuron.
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64
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Amijee H, Bate C, Williams A, Virdee J, Jeggo R, Spanswick D, Scopes DIC, Treherne JM, Mazzitelli S, Chawner R, Eyers CE, Doig AJ. The N-methylated peptide SEN304 powerfully inhibits Aβ(1-42) toxicity by perturbing oligomer formation. Biochemistry 2012; 51:8338-52. [PMID: 23025847 DOI: 10.1021/bi300415v] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Oligomeric forms of β-amyloid (Aβ) have potent neurotoxic activity and are the primary cause of neuronal injury and cell death in Alzheimer's disease (AD). Compounds that perturb oligomer formation or structure may therefore be therapeutic for AD. We previously reported that d-[(chGly)-(Tyr)-(chGly)-(chGly)-(mLeu)]-NH(2) (SEN304) is able to inhibit Aβ aggregation and toxicity, shown primarily by thioflavin T fluorescence and MTT (Kokkoni, N. et al. (2006) N-Methylated peptide inhibitors of β-amyloid aggregation and toxicity. Optimisation of inhibitor structure. Biochemistry 45, 9906-9918). Here we extensively characterize how SEN304 affects Aβ(1-42) aggregation and toxicity, using biophysical assays (thioflavin T, circular dichroism, SDS-PAGE, size exclusion chromatography, surface plasmon resonance, traveling wave ion mobility mass spectrometry, electron microscopy, ELISA), toxicity assays in cell culture (MTT and lactate dehydrogenase in human SH-SHY5Y cells, mouse neuronal cell death and synaptophysin) and long-term potentiation in a rat hippocampal brain slice. These data, with dose response curves, show that SEN304 is a powerful inhibitor of Aβ(1-42) toxicity, particularly effective at preventing Aβ inhibition of long-term potentiation. It can bind directly to Aβ(1-42), delay β-sheet formation and promote aggregation of toxic oligomers into a nontoxic form, with a different morphology that cannot bind thioflavin T. SEN304 appears to work by inducing aggregation, and hence removal, of Aβ oligomers. It is therefore a promising lead compound for Alzheimer's disease.
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Affiliation(s)
- Hozefa Amijee
- Senexis Limited, Babraham Research Campus, Cambridge CB22 3AT, UK
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65
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Tamagnini F, Burattini C, Casoli T, Balietti M, Fattoretti P, Aicardi G. Early impairment of long-term depression in the perirhinal cortex of a mouse model of Alzheimer's disease. Rejuvenation Res 2012; 15:231-4. [PMID: 22533438 DOI: 10.1089/rej.2011.1311] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Visual recognition memory is early impaired in Alzheimer's disease. Long-term depression of synaptic transmission in the perirhinal cortex is critically involved in this form of memory. We found that synaptic transmission was impaired in perirhinal cortex slices obtained from 3-month-old Tg2576 mice, and that 3,000 pulses at 5 Hz induced long-term depression in perirhinal cortex slices from age-matched control mice, but not in those from Tg2576 mice. To our knowledge, these data provide the first evidence of synaptic transmission and long-term depression impairment in the perirhinal cortex in an animal model of Alzheimer's disease, and the earliest synaptic deficit in Tg2576 mice.
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Affiliation(s)
- Francesco Tamagnini
- Department of Human and General Physiology, University of Bologna, Bologna, Italy
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66
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Hamley IW. The Amyloid Beta Peptide: A Chemist’s Perspective. Role in Alzheimer’s and Fibrillization. Chem Rev 2012; 112:5147-92. [DOI: 10.1021/cr3000994] [Citation(s) in RCA: 670] [Impact Index Per Article: 55.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- I. W. Hamley
- Department
of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD,
U.K
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67
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Consequences of inhibiting amyloid precursor protein processing enzymes on synaptic function and plasticity. Neural Plast 2012; 2012:272374. [PMID: 22792491 PMCID: PMC3390164 DOI: 10.1155/2012/272374] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 04/22/2012] [Indexed: 12/21/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease, one of whose major pathological hallmarks is the accumulation of amyloid plaques comprised of aggregated β-amyloid (Aβ) peptides. It is now recognized that soluble Aβ oligomers may lead to synaptic dysfunctions early in AD pathology preceding plaque deposition. Aβ is produced by a sequential cleavage of amyloid precursor protein (APP) by the activity of β- and γ-secretases, which have been identified as major candidate therapeutic targets of AD. This paper focuses on how Aβ alters synaptic function and the functional consequences of inhibiting the activity of the two secretases responsible for Aβ generation. Abnormalities in synaptic function resulting from the absence or inhibition of the Aβ-producing enzymes suggest that Aβ itself may have normal physiological functions which are disrupted by abnormal accumulation of Aβ during AD pathology. This interpretation suggests that AD therapeutics targeting the β- and γ-secretases should be developed to restore normal levels of Aβ or combined with measures to circumvent the associated synaptic dysfunction(s) in order to have minimal impact on normal synaptic function.
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68
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Chang PKY, Verbich D, McKinney RA. AMPA receptors as drug targets in neurological disease - advantages, caveats, and future outlook. Eur J Neurosci 2012; 35:1908-16. [DOI: 10.1111/j.1460-9568.2012.08165.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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69
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Chronic treatment with rivastigmine in patients with Alzheimer’s disease: A study on primary motor cortex excitability tested by 5Hz-repetitive transcranial magnetic stimulation. Clin Neurophysiol 2012; 123:902-9. [DOI: 10.1016/j.clinph.2011.09.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 09/01/2011] [Accepted: 09/05/2011] [Indexed: 12/27/2022]
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70
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Romberg C, McTighe SM, Heath CJ, Whitcomb DJ, Cho K, Bussey TJ, Saksida LM. False recognition in a mouse model of Alzheimer's disease: rescue with sensory restriction and memantine. Brain 2012; 135:2103-14. [PMID: 22466291 PMCID: PMC3381719 DOI: 10.1093/brain/aws074] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Alzheimer’s disease is commonly regarded as a loss of memory for past events. However, patients with Alzheimer’s disease seem not only to forget events but also to express false confidence in remembering events that have never happened. How and why false recognition occurs in such patients is currently unknown, and treatments targeting this specific mnemonic abnormality have not been attempted. Here, we used a modified object recognition paradigm to show that the tgCRND8 mouse—which overexpresses amyloid β and develops amyloid plaques similar to those in the brains of patients with Alzheimer’s disease—exhibits false recognition. Furthermore, we found that false recognition did not occur when tgCRND8 mice were kept in a dark, quiet chamber during the delay, paralleling previous findings in patients with mild cognitive impairment, which is often considered to be prodromal Alzheimer’s disease. Additionally, false recognition did not occur when mice were treated with the partial N-methyl-d-aspartic acid receptor antagonist memantine. In a subsequent experiment, we found abnormally enhanced N-methyl-d-aspartic acid receptor-dependent long-term depression in these mice, which could be normalized by treatment with memantine. We suggest that Alzheimer’s disease typical amyloid β pathology leads to aberrant synaptic plasticity, thereby making memory representations more susceptible to interfering sensory input, thus increasing the likelihood of false recognition. Parallels between these findings and those from the literature on Alzheimer’s disease and mild cognitive impairment suggest a mechanism underlying false recognition in these patients. The false recognition phenomenon may provide a novel paradigm for the discovery of potential therapies to treat the mnemonic dysfunction characteristic of this disease.
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Affiliation(s)
- Carola Romberg
- Department of Experimental Psychology, University of Cambridge, Cambridge CB2 3EB, UK.
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71
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Hu NW, Ondrejcak T, Rowan MJ. Glutamate receptors in preclinical research on Alzheimer's disease: Update on recent advances. Pharmacol Biochem Behav 2012; 100:855-62. [DOI: 10.1016/j.pbb.2011.04.013] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 04/05/2011] [Accepted: 04/15/2011] [Indexed: 01/01/2023]
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Synaptic dysfunction in Alzheimer's disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 970:573-601. [PMID: 22351073 DOI: 10.1007/978-3-7091-0932-8_25] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Generation of amyloid peptide (Aβ) is at the beginning of a cascade that leads to Alzheimer's disease (AD). Amyloid precursor protein (APP), as well as β- and γ-secretases, is the principal player involved in Aβ production, while α-secretase cleavage on APP prevents Aβ deposition. Recent studies suggested that soluble assembly states of Aβ peptides can cause cognitive problems by disrupting synaptic function in the absence of significant neurodegeneration. Therefore, current research investigates the relative importance of these various soluble Aβ assemblies in causing synaptic dysfunction and cognitive deficits. Several Aβ oligomers targets and cellular mechanisms responsible of Aβ-induced synaptic failure have been identified. The first and most important mechanism impugns a toxic gain of function for Aβ which results due to self-association and attainment of new structures capable of novel interactions that lead to impaired plasticity. Other scenarios predicate that Aβ has a normal physiological role. On the one hand, insufficient Aβ could lead to a loss of normal function, whereas excess Aβ may precipitate dysfunction. How this occurs and which the main target/s is/are for the synaptic action of Aβ remains to be fully understood and would certainly represent one of the main challenges to future AD research.
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73
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Ma T, Klann E. Amyloid β: linking synaptic plasticity failure to memory disruption in Alzheimer's disease. J Neurochem 2011; 120 Suppl 1:140-148. [PMID: 22122128 DOI: 10.1111/j.1471-4159.2011.07506.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Mounting evidence suggests that amyloid beta-induced impairments in synaptic plasticity that is accompanied by cognitive decline and dementia represent key pathogenic steps of Alzheimer's disease. In this study, we review recent advances in the study of the molecular and cellular mechanisms underlying Alzheimer's disease-associated synaptic dysfunction and memory deficits, and how these mechanisms could provide novel avenues for therapeutic intervention to treat this devastating neurodegenerative disease.
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Affiliation(s)
- Tao Ma
- Center for Neural Science, New York University, New York, New York, USA
| | - Eric Klann
- Center for Neural Science, New York University, New York, New York, USA
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74
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Goebel-Goody SM, Baum M, Paspalas CD, Fernandez SM, Carty NC, Kurup P, Lombroso PJ. Therapeutic implications for striatal-enriched protein tyrosine phosphatase (STEP) in neuropsychiatric disorders. Pharmacol Rev 2011; 64:65-87. [PMID: 22090472 DOI: 10.1124/pr.110.003053] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Striatal-enriched protein tyrosine phosphatase (STEP) is a brain-specific phosphatase that modulates key signaling molecules involved in synaptic plasticity and neuronal function. Targets include extracellular-regulated kinase 1 and 2 (ERK1/2), stress-activated protein kinase p38 (p38), the Src family tyrosine kinase Fyn, N-methyl-D-aspartate receptors (NMDARs), and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs). STEP-mediated dephosphorylation of ERK1/2, p38, and Fyn leads to inactivation of these enzymes, whereas STEP-mediated dephosphorylation of surface NMDARs and AMPARs promotes their endocytosis. Accordingly, the current model of STEP function posits that it opposes long-term potentiation and promotes long-term depression. Phosphorylation, cleavage, dimerization, ubiquitination, and local translation all converge to maintain an appropriate balance of STEP in the central nervous system. Accumulating evidence over the past decade indicates that STEP dysregulation contributes to the pathophysiology of several neuropsychiatric disorders, including Alzheimer's disease, schizophrenia, fragile X syndrome, epileptogenesis, alcohol-induced memory loss, Huntington's disease, drug abuse, stroke/ischemia, and inflammatory pain. This comprehensive review discusses STEP expression and regulation and highlights how disrupted STEP function contributes to the pathophysiology of diverse neuropsychiatric disorders.
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Affiliation(s)
- Susan M Goebel-Goody
- Child Study Center, Yale University School of Medicine, New Haven, Connecticut, USA
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75
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Koffie RM, Hyman BT, Spires-Jones TL. Alzheimer's disease: synapses gone cold. Mol Neurodegener 2011; 6:63. [PMID: 21871088 PMCID: PMC3178498 DOI: 10.1186/1750-1326-6-63] [Citation(s) in RCA: 203] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 08/26/2011] [Indexed: 11/21/2022] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by insidious cognitive decline and memory dysfunction. Synapse loss is the best pathological correlate of cognitive decline in AD and mounting evidence suggests that AD is primarily a disease of synaptic dysfunction. Soluble oligomeric forms of amyloid beta (Aβ), the peptide that aggregates to form senile plaques in the brain of AD patients, have been shown to be toxic to neuronal synapses both in vitro and in vivo. Aβ oligomers inhibit long-term potentiation (LTP) and facilitate long-term depression (LTD), electrophysiological correlates of memory formation. Furthermore, oligomeric Aβ has also been shown to induce synapse loss and cognitive impairment in animals. The molecular underpinnings of these observations are now being elucidated, and may provide clear therapeutic targets for effectively treating the disease. Here, we review recent findings concerning AD pathogenesis with a particular focus on how Aβ impacts synapses.
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Affiliation(s)
- Robert M Koffie
- Massachusetts General Hospital, Harvard Medical School, 114 16th Street, Charlestown, MA 02129, USA.
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76
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Changes in the physiology of CA1 hippocampal pyramidal neurons in preplaque CRND8 mice. Neurobiol Aging 2011; 33:1609-23. [PMID: 21676499 DOI: 10.1016/j.neurobiolaging.2011.05.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 04/19/2011] [Accepted: 05/03/2011] [Indexed: 12/16/2022]
Abstract
Amyloid-β protein (Aβ) is thought to play a central pathogenic role in Alzheimer's disease. Aβ can impair synaptic transmission, but little is known about the effects of Aβ on intrinsic cellular properties. Here we compared the cellular properties of CA1 hippocampal pyramidal neurons in acute slices from preplaque transgenic (Tg+) CRND8 mice and wild-type (Tg-) littermates. CA1 pyramidal neurons from Tg+ mice had narrower action potentials with faster decays than neurons from Tg- littermates. Action potential-evoked intracellular Ca(2+) transients in the apical dendrite were smaller in Tg+ than in Tg- neurons. Resting calcium concentration was higher in Tg+ than in Tg- neurons. The difference in action potential waveform was eliminated by low concentrations of tetraethylammonium ions and of 4-aminopyridine, implicating a fast delayed-rectifier potassium current. Consistent with this suggestion, there was a small increase in immunoreactivity for Kv3.1b in stratum radiatum in Tg+ mice. These changes in intrinsic properties may affect information flow through the hippocampus and contribute to the behavioral deficits observed in mouse models and patients with early-stage Alzheimer's disease.
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77
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Abstract
Transmissible spongiform encephalopathies, or prion diseases, are lethal neurodegenerative disorders caused by the infectious agent named prion, whose main constituent is an aberrant conformational isoform of the cellular prion protein, PrP(C) . The mechanisms of prion-associated neurodegeneration and the physiologic function of PrP(C) are still unclear, although it is now increasingly acknowledged that PrP(C) plays a role in cell differentiation and survival. PrP(C) thus exhibits dichotomic attributes, as it can switch from a benign function under normal conditions to the triggering of neuronal death during disease. By reviewing data from models of prion infection and PrP-knockout paradigms, here we discuss the possibility that Ca(2+) is the hidden factor behind the multifaceted behavior of PrP(C) . By featuring in almost all processes of cell signaling, Ca(2+) might explain diverse aspects of PrP(C) pathophysiology, including the recently proposed one in which PrP(C) acts as a mediator of synaptic degeneration in Alzheimer's disease.
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78
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Puzzo D, Privitera L, Fa' M, Staniszewski A, Hashimoto G, Aziz F, Sakurai M, Ribe EM, Troy CM, Mercken M, Jung SS, Palmeri A, Arancio O. Endogenous amyloid-β is necessary for hippocampal synaptic plasticity and memory. Ann Neurol 2011; 69:819-30. [PMID: 21472769 DOI: 10.1002/ana.22313] [Citation(s) in RCA: 221] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 09/10/2010] [Accepted: 10/15/2010] [Indexed: 11/08/2022]
Abstract
OBJECTIVE The goal of this study was to investigate the role of endogenous amyloid-β peptide (Aβ) in healthy brain. METHODS Long-term potentiation (LTP), a type of synaptic plasticity that is thought to be associated with learning and memory, was examined through extracellular field recordings from the CA1 region of hippocampal slices, whereas behavioral techniques were used to assess contextual fear memory and reference memory. Amyloid precursor protein (APP) expression was reduced through small interfering RNA (siRNA) technique. RESULTS We found that both antirodent Aβ antibody and siRNA against murine APP reduced LTP as well as contextual fear memory and reference memory. These effects were rescued by the addition of human Aβ₄₂, suggesting that endogenously produced Aβ is needed for normal LTP and memory. Furthermore, the effect of endogenous Aβ on plasticity and memory was likely due to regulation of transmitter release, activation of α7-containing nicotinic acetylcholine receptors, and Aβ₄₂ production. INTERPRETATION Endogenous Aβ₄₂ is a critical player in synaptic plasticity and memory within the normal central nervous system. This needs to be taken into consideration when designing therapies aiming at reducing Aβ levels to treat Alzheimer disease.
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Affiliation(s)
- Daniela Puzzo
- Department of Pathology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY 10032, USA
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79
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Kapai NA, Solntseva EI, Skrebitskii VG. Donepezil eliminates suppressive effects of β-amyloid peptide (1-42) on long-term potentiation in the hippocampus. Bull Exp Biol Med 2011; 149:33-6. [PMID: 21113452 DOI: 10.1007/s10517-010-0868-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
β-Amyloid peptide 1-42 in a concentration of 200 nM impairs induction of long-term posttetanic potentiation of population spike in CA1 pyramidal neurons in rat hippocampal slices. Application of donepezil, a drug used for the treatment of Alzheimer disease, in a concentration of 1 μM eliminates the suppressive effect of β-amyloid peptide 1-42 on long-term posttenanic potentiation in the hippocampus.
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Affiliation(s)
- N A Kapai
- Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia
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80
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Liu HP, Lin WY, Wu BT, Liu SH, Wang WF, Tsai CH, Lee CC, Tsai FJ. Evaluation of the poly(ADP-ribose) polymerase-1 gene variants in Alzheimer's disease. J Clin Lab Anal 2011; 24:182-6. [PMID: 20486200 DOI: 10.1002/jcla.20379] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Amyloid peptide is thought to play a critical role in neuronal death in Alzheimer's disease (AD), most likely through oxidative stress. Free radical-related injury leads to DNA breaks, which subsequently activates the repair enzyme poly(ADP-ribose) polymerase-1 (PARP-1). In this study, the relationship between genetic variants situated at the PARP-1 gene and AD development was investigated. We performed a case and control study from a Taiwanese population enrolled 120 AD patients and 111 healthy controls by using a polymerase chain reaction restriction fragment length polymorphism approach for two PARP-1 exonic polymorphisms, 414C/T (rs1805404) and 2456T/C (rs1136410), corresponding to protein residues at positions 81Asp/Asp and 762Val/Ala. There were no significant differences in allele or genotype frequencies for either PARP-1 gene variant between the case and control groups; however, upon analysis of the haplotype distribution, four haplotypes (Hts) were identified. We found that the distributions of Ht3-TT and Ht4-CC were significantly associated with an increased risk of AD (P<0.0001), whereas the Ht1-TC haplotype showed a protective effect for cases compared with the control group (P<0.05). These results reveal that the PARP-1 gene is highly associated with AD susceptibility and might contribute to a critical mechanism that mediates cell survival or death as a response to cytotoxic stress.
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Affiliation(s)
- Hsin-Ping Liu
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan
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81
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Rushworth JV, Hooper NM. Lipid Rafts: Linking Alzheimer's Amyloid-β Production, Aggregation, and Toxicity at Neuronal Membranes. Int J Alzheimers Dis 2010; 2011:603052. [PMID: 21234417 PMCID: PMC3014710 DOI: 10.4061/2011/603052] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 11/03/2010] [Indexed: 01/03/2023] Open
Abstract
Lipid rafts are membrane microdomains, enriched in cholesterol and sphingolipids, into which specific subsets of proteins and lipids partition, creating cell-signalling platforms that are vital for neuronal functions. Lipid rafts play at least three crucial roles in Alzheimer's Disease (AD), namely, in promoting the generation of the amyloid-β (Aβ) peptide, facilitating its aggregation upon neuronal membranes to form toxic oligomers and hosting specific neuronal receptors through which the AD-related neurotoxicity and memory impairments of the Aβ oligomers are transduced. Recent evidence suggests that Aβ oligomers may exert their deleterious effects through binding to, and causing the aberrant clustering of, lipid raft proteins including the cellular prion protein and glutamate receptors. The formation of these pathogenic lipid raft-based platforms may be critical for the toxic signalling mechanisms that underlie synaptic dysfunction and neuropathology in AD.
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Affiliation(s)
- Jo V. Rushworth
- Institute of Molecular and Cellular Biology, Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Nigel M. Hooper
- Institute of Molecular and Cellular Biology, Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, LIGHT Laboratories, Clarendon Way, University of Leeds, Leeds LS2 9JT, UK
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82
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Van der Jeugd A, Ahmed T, Burnouf S, Belarbi K, Hamdame M, Grosjean ME, Humez S, Balschun D, Blum D, Buée L, D'Hooge R. Hippocampal tauopathy in tau transgenic mice coincides with impaired hippocampus-dependent learning and memory, and attenuated late-phase long-term depression of synaptic transmission. Neurobiol Learn Mem 2010; 95:296-304. [PMID: 21167950 DOI: 10.1016/j.nlm.2010.12.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 12/08/2010] [Accepted: 12/09/2010] [Indexed: 12/30/2022]
Abstract
We evaluated various forms of hippocampus-dependent learning and memory, and hippocampal synaptic plasticity in THY-Tau22 transgenic mice, a murine tauopathy model that expresses double-mutated 4-repeat human tau, and shows neuropathological tau hyperphosphorylation and aggregation throughout the brain. Focussing on hippocampus, immunohistochemical studies in aged THY-Tau22 mice revealed prominent hyper- and abnormal phosphorylation of tau in CA1 region, and an increase in glial fibrillary acidic protein (GFAP) in hippocampus, but without signs of neuronal loss. These mice displayed spatial, social, and contextual learning and memory defects that could not be reduced to subtle neuromotor disability. The behavioral defects coincided with changes in hippocampal synaptic functioning and plasticity as measured in paired-pulse and novel long-term depression protocols. These results indicate that hippocampal tauopathy without neuronal cell loss can impair neural and behavioral plasticity, and further show that transgenic mice, such as the THY-Tau22 strain, might be useful for preclinical research on tauopathy pathogenesis and possible treatment.
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Affiliation(s)
- Ann Van der Jeugd
- Laboratory of Biological Psychology, Department of Psychology, Catholic University of Leuven, Belgium
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83
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Boland B, Smith DA, Mooney D, Jung SS, Walsh DM, Platt FM. Macroautophagy is not directly involved in the metabolism of amyloid precursor protein. J Biol Chem 2010; 285:37415-26. [PMID: 20864542 PMCID: PMC2988347 DOI: 10.1074/jbc.m110.186411] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Alterations in the metabolism of amyloid precursor protein (APP) are believed to
play a central role in Alzheimer disease pathogenesis. Burgeoning data indicate
that APP is proteolytically processed in endosomal-autophagic-lysosomal
compartments. In this study, we used both in vivo and
in vitro paradigms to determine whether alterations in
macroautophagy affect APP metabolism. Three mouse models of glycosphingolipid
storage diseases, namely Niemann-Pick type C1, GM1 gangliosidosis, and Sandhoff
disease, had mTOR-independent increases in the autophagic vacuole
(AV)-associated protein, LC3-II, indicative of impaired lysosomal flux. APP
C-terminal fragments (APP-CTFs) were also increased in brains of the three mouse
models; however, discrepancies between LC3-II and APP-CTFs were seen between
primary (GM1 gangliosidosis and Sandhoff disease) and secondary (Niemann-Pick
type C1) lysosomal storage models. APP-CTFs were proportionately higher than
LC3-II in cerebellar regions of GM1 gangliosidosis and Sandhoff disease,
although LC3-II increased before APP-CTFs in brains of NPC1 mice. Endogenous
murine Aβ40 from RIPA-soluble extracts was increased in brains of all
three mice. The in vivo relationship between AV and APP-CTF
accumulation was also seen in cultured neurons treated with agents that impair
primary (chloroquine and leupeptin + pepstatin) and secondary (U18666A
and vinblastine) lysosomal flux. However, Aβ secretion was unaffected by
agents that induced autophagy (rapamycin) or impaired AV clearance, and
LC3-II-positive AVs predominantly co-localized with degradative LAMP-1-positive
lysosomes. These data suggest that neuronal macroautophagy does not directly
regulate APP metabolism but highlights the important anti-amyloidogenic role of
lysosomal proteolysis in post-secretase APP-CTF catabolism.
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Affiliation(s)
- Barry Boland
- Laboratory for Neurodegenerative Research, School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Dublin 4, Ireland.
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84
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Palop JJ, Mucke L. Amyloid-beta-induced neuronal dysfunction in Alzheimer's disease: from synapses toward neural networks. Nat Neurosci 2010; 13:812-8. [PMID: 20581818 DOI: 10.1038/nn.2583] [Citation(s) in RCA: 1191] [Impact Index Per Article: 85.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Alzheimer's disease is the most frequent neurodegenerative disorder and the most common cause of dementia in the elderly. Diverse lines of evidence suggest that amyloid-beta (Abeta) peptides have a causal role in its pathogenesis, but the underlying mechanisms remain uncertain. Here we discuss recent evidence that Abeta may be part of a mechanism controlling synaptic activity, acting as a positive regulator presynaptically and a negative regulator postsynaptically. The pathological accumulation of oligomeric Abeta assemblies depresses excitatory transmission at the synaptic level, but also triggers aberrant patterns of neuronal circuit activity and epileptiform discharges at the network level. Abeta-induced dysfunction of inhibitory interneurons likely increases synchrony among excitatory principal cells and contributes to the destabilization of neuronal networks. Strategies that block these Abeta effects may prevent cognitive decline in Alzheimer's disease. Potential obstacles and next steps toward this goal are discussed.
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Affiliation(s)
- Jorge J Palop
- Gladstone Institute of Neurological Disease and Department of Neurology, University of California, San Francisco, California, USA.
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85
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Rui Y, Gu J, Yu K, Hartzell HC, Zheng JQ. Inhibition of AMPA receptor trafficking at hippocampal synapses by beta-amyloid oligomers: the mitochondrial contribution. Mol Brain 2010; 3:10. [PMID: 20346152 PMCID: PMC2853530 DOI: 10.1186/1756-6606-3-10] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Accepted: 03/26/2010] [Indexed: 01/12/2023] Open
Abstract
Background Synaptic defects represent a major mechanism underlying altered brain functions of patients suffering Alzheimer's disease (AD) [1-3]. An increasing body of work indicates that the oligomeric forms of β-amyloid (Aβ) molecules exert profound inhibition on synaptic functions and can cause a significant loss of neurotransmitter receptors from the postsynaptic surface, but the underlying mechanisms remain poorly understood. In this study, we investigated a potential contribution of mitochondria to Aβ inhibition of AMPA receptor (AMPAR) trafficking. Results We found that a brief exposure of hippocampal neurons to Aβ oligomers not only led to marked removal of AMPARs from postsynaptic surface but also impaired rapid AMPAR insertion during chemically-induced synaptic potentiation. We also found that Aβ oligomers exerted acute impairment of fast mitochondrial transport, as well as mitochondrial translocation into dendritic spines in response to repetitive membrane depolarization. Quantitative analyses at the single spine level showed a positive correlation between spine-mitochondria association and the surface accumulation of AMPARs. In particular, we found that spines associated with mitochondria tended to be more resistant to Aβ inhibition on AMPAR trafficking. Finally, we showed that inhibition of GSK3β alleviated Aβ impairment of mitochondrial transport, and effectively abolished Aβ-induced AMPAR loss and inhibition of AMPAR insertion at spines during cLTP. Conclusions Our findings indicate that mitochondrial association with dendritic spines may play an important role in supporting AMPAR presence on or trafficking to the postsynaptic membrane. Aβ disruption of mitochondrial trafficking could contribute to AMPAR removal and trafficking defects leading to synaptic inhibition.
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Affiliation(s)
- Yanfang Rui
- Departments of Cell Biology and Neurology, Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322, USA
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86
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Randall AD, Witton J, Booth C, Hynes-Allen A, Brown JT. The functional neurophysiology of the amyloid precursor protein (APP) processing pathway. Neuropharmacology 2010; 59:243-67. [PMID: 20167227 DOI: 10.1016/j.neuropharm.2010.02.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 02/11/2010] [Indexed: 01/12/2023]
Abstract
Amyloid beta (Abeta) peptides derived from proteolytic cleavage of amyloid precursor protein (APP) are thought to be a pivotal toxic species in the pathogenesis of Alzheimer's disease (AD). Furthermore, evidence has been accumulating that components of APP processing pathway are involved in non-pathological normal function of the CNS. In this review we aim to cover the extensive body of research aimed at understanding how components of this pathway contribute to neurophysiological function of the CNS in health and disease. We briefly outline changes to clinical neurophysiology seen in AD patients before discussing functional changes in mouse models of AD which range from changes to basal synaptic transmission and synaptic plasticity through to abnormal synchronous network activity. We then describe the various neurophysiological actions that are produced by application of exogenous Abeta in various forms, and finally discuss a number or other neurophysiological aspects of the APP pathway, including functional activities of components of secretase complexes other than Abeta production.
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Affiliation(s)
- A D Randall
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol School of Medical Sciences, Bristol, UK.
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87
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88
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Cousins SL, Hoey SEA, Anne Stephenson F, Perkinton MS. Amyloid precursor protein 695 associates with assembled NR2A- and NR2B-containing NMDA receptors to result in the enhancement of their cell surface delivery. J Neurochem 2009; 111:1501-13. [PMID: 19811606 DOI: 10.1111/j.1471-4159.2009.06424.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This is a study of the interaction between the two NMDA neurotransmitter receptor subtypes, NR1/NR2A and NR1/NR2B, and amyloid precursor protein (APP) 695, the major APP variant expressed in neurones. APP695 co-immunoprecipitated with assembled NR1-1a/NR2A and NR1-1a/NR2B NMDA receptors following expression in mammalian cells. Single NR1-1a, NR1-2a, NR1-4b(c-Myc), or NR2 subunit transfections revealed that co-association of APP695 with assembled NMDA receptors was mediated via the NR1 subunit; it was independent of the NR1 C1, C2, and C2' cassettes and, the use of an NR1-2a(c-Myc)-trafficking mutant suggested that interaction between the two proteins occurs in the endoplasmic reticulum. The use of antibodies directed against extracellular and intracellular NR2 subunit epitopes for immunoprecipitations suggested that APP/NMDA receptor association was mediated via N-terminal domains. Anti-APP antibodies immunoprecipitated NR1, NR2A, and NR2B immunoreactive bands from detergent extracts of mammalian brain; reciprocally, anti-NR1 or anti-NR2A antibodies co-immunoprecipitated APP immunoreactivity. Immune pellets from brain were sensitive to endoglycosidase H suggesting that, as for heterologous expression, APP and NMDA receptor association occurs in the endoplasmic reticulum. Co-expression of APP695 in mammalian cells resulted in enhanced cell surface expression of both NR1-1a/NR2A and NR1-1a/NR2B NMDA receptors with no increase in total subunit expression. These findings are further evidence for a role of APP in intracellular trafficking mechanisms. Further, they provide a link between two major brain proteins that have both been implicated in Alzheimer's disease.
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89
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Ondrejcak T, Klyubin I, Hu NW, Barry AE, Cullen WK, Rowan MJ. Alzheimer's disease amyloid beta-protein and synaptic function. Neuromolecular Med 2009; 12:13-26. [PMID: 19757208 DOI: 10.1007/s12017-009-8091-0] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Accepted: 08/25/2009] [Indexed: 12/15/2022]
Abstract
Alzheimer's disease (AD) is characterized neuropathologically by the deposition of different forms of amyloid beta-protein (A beta) including variable amounts of soluble species that correlate with severity of dementia. The extent of synaptic loss in the brain provides the best morphological correlate of cognitive impairment in clinical AD. Animal research on the pathophysiology of AD has therefore focussed on how soluble A beta disrupts synaptic mechanisms in vulnerable brain regions such as the hippocampus. Synaptic plasticity in the form of persistent activity-dependent increases or decreases in synaptic strength provide a neurophysiological substrate for hippocampal-dependent learning and memory. Acute treatment with human-derived or chemically prepared soluble A beta that contains certain oligomeric assemblies, potently and selectively disrupts synaptic plasticity causing inhibition of long-term potentiation (LTP) and enhancement of long-term depression (LTD) of glutamatergic transmission. Over time these and related actions of A beta have been implicated in reducing synaptic integrity. This review addresses the involvement of neurotransmitter intercellular signaling in mediating or modulating the synaptic plasticity disrupting actions of soluble A beta, with particular emphasis on the different roles of glutamatergic and cholinergic mechanisms. There is growing evidence to support the view that NMDA and possibly nicotinic receptors are critically involved in mediating the disruptive effect of A beta and that targeting muscarinic receptors can indirectly modulate A beta's actions. Such studies should help inform ongoing and future clinical trials of drugs acting through the glutamatergic and cholinergic systems.
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Affiliation(s)
- Tomas Ondrejcak
- Department of Pharmacology and Therapeutics, Biotechnology Building and Institute of Neuroscience, Trinity College, Dublin 2, Ireland
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90
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Li S, Hong S, Shepardson NE, Walsh DM, Shankar GM, Selkoe D. Soluble oligomers of amyloid Beta protein facilitate hippocampal long-term depression by disrupting neuronal glutamate uptake. Neuron 2009; 62:788-801. [PMID: 19555648 DOI: 10.1016/j.neuron.2009.05.012] [Citation(s) in RCA: 721] [Impact Index Per Article: 48.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 03/06/2009] [Accepted: 05/06/2009] [Indexed: 12/22/2022]
Abstract
In Alzheimer's disease (AD), the impairment of declarative memory coincides with the accumulation of extracellular amyloid-beta protein (Abeta) and intraneuronal tau aggregates. Dementia severity correlates with decreased synapse density in hippocampus and cortex. Although numerous studies show that soluble Abeta oligomers inhibit hippocampal long-term potentiation, their role in long-term synaptic depression (LTD) remains unclear. Here, we report that soluble Abeta oligomers from several sources (synthetic, cell culture, human brain extracts) facilitated electrically evoked LTD in the CA1 region. Abeta-enhanced LTD was mediated by mGluR or NMDAR activity. Both forms of LTD were prevented by an extracellular glutamate scavenger system. Abeta-facilitated LTD was mimicked by the glutamate reuptake inhibitor TBOA, including a shared dependence on extracellular calcium levels and activation of PP2B and GSK-3 signaling. In accord, synaptic glutamate uptake was significantly decreased by soluble Abeta. We conclude that soluble Abeta oligomers perturb synaptic plasticity by altering glutamate recycling at the synapse and promoting synapse depression.
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Affiliation(s)
- Shaomin Li
- Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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91
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Abstract
The age of an experimental animal can be a critical variable, yet age matters are often overlooked within neuroscience. Many studies make use of young animals, without considering possible differences between immature and mature subjects. This is especially problematic when attempting to model traits or diseases that do not emerge until adulthood. In this commentary we discuss the reasons for this apparent bias in age of experimental animals, and illustrate the problem with a systematic review of published articles on long-term potentiation. Additionally, we review the developmental stages of a rat and discuss the difficulty of using the weight of an animal as a predictor of its age. Finally, we provide original data from our laboratory and review published data to emphasize that development is an ongoing process that does not end with puberty. Developmental changes can be quantitative in nature, involving gradual changes, rapid switches, or inverted U-shaped curves. Changes can also be qualitative. Thus, phenomena that appear to be unitary may be governed by different mechanisms at different ages. We conclude that selection of the age of the animals may be critically important in the design and interpretation of neurobiological studies.
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Affiliation(s)
- James Edgar McCutcheon
- Department of Cellular and Molecular Pharmacology, Rosalind Franklin University of Medicine and Science, The Chicago Medical School, 3333 Green Bay Road, North Chicago, IL 60064, USA
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92
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Cheng L, Yin WJ, Zhang JF, Qi JS. Amyloid beta-protein fragments 25-35 and 31-35 potentiate long-term depression in hippocampal CA1 region of rats in vivo. Synapse 2009; 63:206-14. [PMID: 19072840 DOI: 10.1002/syn.20599] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Amyloid beta-protein (Abeta) is thought to be responsible for the deficit of learning and memory in Alzheimer's disease (AD), possibly through interfering with synaptic plasticity in the brain. It has been reported that Abeta fragments suppress the long-term potentiation (LTP) of synaptic transmission. However, it is unclear whether Abeta fragments can regulate long-term depression (LTD), an equally important form of synaptic plasticity in the brain. The present study investigates the effects of Abeta fragments on LTD induced by low frequency stimulation (LFS) in the hippocampus in vivo. Our results showed that (1) prolonged 1-10 Hz of LFS all effectively elicited LTD, which could persist for at least 2 h and be reversed by high frequency stimulation (HFS); (2) the effectiveness of LTD induction depended mainly on the number of pulses but not the frequency of LFS; (3) pretreatment with Abeta fragment 25-35 (Abeta(25-35), 12.5 and 25 nmol) did not change baseline field excitatory postsynaptic potentials but dose-dependently potentiated LTD; (4) Abeta fragment 31-35 (Abeta(31-35)), a shorter Abeta fragment than Abeta(25-35), also dose-dependently strengthened LFS-induced hippocampal LTD. Thus, the present study demonstrates the enhancement of hippocampal LTD by Abeta in in vivo condition. We propose that Abeta-induced potentiation of LTD, together with the suppression of LTP, will result in the impairment of cognitive function of the brain.
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Affiliation(s)
- Li Cheng
- Department of Neurobiology, Key Laboratory of Cellular Physiology, Shanxi Medical University, Taiyuan, Shanxi, People's Republic of China
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93
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Oligomeric amyloid-beta peptide disrupts phosphatidylinositol-4,5-bisphosphate metabolism. Nat Neurosci 2008; 11:547-54. [PMID: 18391946 DOI: 10.1038/nn.2100] [Citation(s) in RCA: 150] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2007] [Accepted: 02/29/2008] [Indexed: 01/07/2023]
Abstract
Synaptic dysfunction caused by oligomeric assemblies of amyloid-beta peptide (Abeta) has been linked to cognitive deficits in Alzheimer's disease. Here we found that incubation of primary cortical neurons with oligomeric Abeta decreases the level of phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2), a phospholipid that regulates key aspects of neuronal function. The destabilizing effect of Abeta on PtdIns(4,5)P2 metabolism was Ca2+-dependent and was not observed in neurons that were derived from mice that are haploinsufficient for Synj1. This gene encodes synaptojanin 1, the main PtdIns(4,5)P2 phosphatase in the brain and at the synapses. We also found that the inhibitory effect of Abeta on hippocampal long-term potentiation was strongly suppressed in slices from Synj1+/- mice, suggesting that Abeta-induced synaptic dysfunction can be ameliorated by treatments that maintain the normal PtdIns(4,5)P2 balance in the brain.
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94
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Parameshwaran K, Dhanasekaran M, Suppiramaniam V. Amyloid beta peptides and glutamatergic synaptic dysregulation. Exp Neurol 2007; 210:7-13. [PMID: 18053990 DOI: 10.1016/j.expneurol.2007.10.008] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Revised: 10/03/2007] [Accepted: 10/05/2007] [Indexed: 10/22/2022]
Abstract
Alzheimer's disease (AD) is a major neurodegenerative disorder in which overproduction and accumulation of amyloid beta (Abeta) peptides result in synaptic dysfunction. Recent reports strongly suggest that in the initial stages of AD glutamate receptors are dysregulated by Abeta accumulation resulting in disruption of glutamatergic synaptic transmission which parallels early cognitive deficits. In the presence of Abeta, 2-amino-3-(3-hydoxy-5-methylisoxazol-4-yl) propionic acid (AMPA) glutamate receptor function is disrupted and the surface expression is reduced. Abeta has also been shown to modulate N-methyl-d-aspartate receptors (NMDARs) and metabotropic glutamate receptors. The Abeta mediated glutamate receptor modifications can lead to synaptic dysfunction resulting in excitotoxic neurodegeneration during the progression of AD. This review discusses the recent findings that glutamatergic signaling could be compromised by Abeta induced modulation of synaptic glutamate receptors in specific brain regions.
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Affiliation(s)
- Kodeeswaran Parameshwaran
- Department of Pharmacal Sciences, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, USA
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95
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Parsons CG, Stöffler A, Danysz W. Memantine: a NMDA receptor antagonist that improves memory by restoration of homeostasis in the glutamatergic system--too little activation is bad, too much is even worse. Neuropharmacology 2007; 53:699-723. [PMID: 17904591 DOI: 10.1016/j.neuropharm.2007.07.013] [Citation(s) in RCA: 464] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 06/19/2007] [Accepted: 07/17/2007] [Indexed: 12/13/2022]
Abstract
The neurotransmitter glutamate activates several classes of metabotropic receptor and three major types of ionotropic receptor--alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), kainate and N-methyl-D-aspartate (NMDA). The involvement of glutamate mediated neurotoxicity in the pathogenesis of Alzheimer's disease (AD) is finding increasing scientific acceptance. Central to this hypothesis is the assumption that glutamate receptors, in particular of the NMDA type, are overactivated in a tonic rather than a phasic manner. Such continuous, mild, chronic activation ultimately leads to neuronal damage/death. Additionally, impairment of synaptic plasticity (learning) may result not only from neuronal damage per se but may also be a direct consequence of this continuous, non-contingent NMDA receptor activation. Complete NMDA receptor blockade has also been shown to impair neuronal plasticity, thus, both hypo- and hyperactivity of the glutamatergic system leads to dysfunction. Memantine received marketing authorization from the EMEA (European Medicines Agency) for the treatment of moderate to severe AD in Europe and was subsequently also approved by the FDA (Food and Drug Administration) for use in the same indication in the USA. Memantine is a moderate affinity, uncompetitive NMDA receptor antagonist with strong voltage-dependency and fast kinetics. This review summarizes existing hypotheses on the mechanism of action (MOA) of memantine in an attempt to understand how the accepted interaction with NMDA receptors could allow memantine to provide both neuroprotection and reverse deficits in learning/memory by the same MOA.
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Affiliation(s)
- Chris G Parsons
- Merz Pharmaceuticals, Eckenheimer Landstrasse 100, 60318 Frankfurt am Main, Germany
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96
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Crouch PJ, Harding SME, White AR, Camakaris J, Bush AI, Masters CL. Mechanisms of A beta mediated neurodegeneration in Alzheimer's disease. Int J Biochem Cell Biol 2007; 40:181-98. [PMID: 17804276 DOI: 10.1016/j.biocel.2007.07.013] [Citation(s) in RCA: 185] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Revised: 06/30/2007] [Accepted: 07/24/2007] [Indexed: 11/24/2022]
Abstract
Development of a comprehensive therapeutic treatment for the neurodegenerative Alzheimer's disease (AD) is limited by our understanding of the underlying biochemical mechanisms that drive neuronal failure. Numerous dysfunctional mechanisms have been described in AD, ranging from protein aggregation and oxidative stress to biometal dyshomeostasis and mitochondrial failure. In this review we discuss the critical role of amyloid-beta (A beta) in some of these potential mechanisms of neurodegeneration. The 39-43 amino acid A beta peptide has attracted intense research focus since it was identified as a major constituent of the amyloid deposits that characterise the AD brain, and it is now widely recognised as central to the development of AD. Familial forms of AD involve mutations that lead directly to altered A beta production from the amyloid-beta A4 precursor protein, and the degree of AD severity correlates with specific pools of A beta within the brain. A beta contributes directly to oxidative stress, mitochondrial dysfunction, impaired synaptic transmission, the disruption of membrane integrity, and impaired axonal transport. Further study of the mechanisms of A beta mediated neurodegeneration will considerably improve our understanding of AD, and may provide fundamental insights needed for the development of more effective therapeutic strategies.
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Affiliation(s)
- Peter J Crouch
- Department of Pathology, The University of Melbourne, Victoria 3010, Australia.
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97
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Foster TC, Kumar A. Susceptibility to induction of long-term depression is associated with impaired memory in aged Fischer 344 rats. Neurobiol Learn Mem 2007; 87:522-35. [PMID: 17276704 PMCID: PMC1896085 DOI: 10.1016/j.nlm.2006.12.009] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Revised: 12/15/2006] [Accepted: 12/18/2006] [Indexed: 02/03/2023]
Abstract
The current study employed aged and young male Fischer 344 rats to examine the relationship between long-term depression (LTD), age, and memory. Memory performance was measured on two tasks that are sensitive to hippocampal function; inhibitory avoidance and spatial discrimination on the Morris water maze. The slope of the extracellular excitatory postsynaptic field potential was recorded from CA3-CA1 synapses in hippocampal slices. Low frequency stimulation (LFS) induced a modest LTD only in aged animals under standard recording conditions. The decrease in synaptic transmission examined only in aged animals correlated with memory scores on the spatial task and LTD was not observed in aged animals with the highest memory scores. LTD induction was facilitated by increasing the Ca(2+)/Mg(2+) ratio of the recording medium or employing a paired-pulse stimulation paradigm. Age differences disappeared when LFS was delivered under conditions of elevated Ca(2+)/Mg(2+) in the recording medium. Using multiple induction episodes under conditions which facilitate LTD-induction, no age-related difference was observed in the maximum level of LTD. The results indicate that the increased susceptibility to LTD induction is associated with impaired memory and results from a shift in the induction process. The possible relationship between LTD and memory function is discussed.
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Affiliation(s)
- Thomas C Foster
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
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98
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Hsieh H, Boehm J, Sato C, Iwatsubo T, Tomita T, Sisodia S, Malinow R. AMPAR removal underlies Abeta-induced synaptic depression and dendritic spine loss. Neuron 2007; 52:831-43. [PMID: 17145504 PMCID: PMC1850952 DOI: 10.1016/j.neuron.2006.10.035] [Citation(s) in RCA: 814] [Impact Index Per Article: 47.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 06/10/2006] [Accepted: 10/26/2006] [Indexed: 12/15/2022]
Abstract
Beta amyloid (Abeta), a peptide generated from the amyloid precursor protein (APP) by neurons, is widely believed to underlie the pathophysiology of Alzheimer's disease. Recent studies indicate that this peptide can drive loss of surface AMPA and NMDA type glutamate receptors. We now show that Abeta employs signaling pathways of long-term depression (LTD) to drive endocytosis of synaptic AMPA receptors. Synaptic removal of AMPA receptors is necessary and sufficient to produce loss of dendritic spines and synaptic NMDA responses. Our studies indicate the central role played by AMPA receptor trafficking in Abeta-induced modification of synaptic structure and function.
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Affiliation(s)
- Helen Hsieh
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
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99
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Falkenburger BH, Schulz JB. Limitations of cellular models in Parkinson's disease research. JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 2006:261-8. [PMID: 17017539 DOI: 10.1007/978-3-211-45295-0_40] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Cell cultures for Parkinson's disease research have the advantage of virtually unlimited access, they allow rapid screening for disease pathogenesis and drug candidates, and they restrict the necessary number of animal experiments. Limitations of cell cultures, include that the survival of neurons is dependent upon the culture conditions; that the cells do not develop their natural neuronal networks. In most cases, neurons are deprived from the physiological afferent and efferent connections. In Parkinson's disease research, mesencephalic slice cultures, primary immature dopaminergic neurons and immortalized cell lines--either in a proliferating state or in a differentiated state--are used. Neuronal cultures may be plated in the presence or absence of glial cells and serum. These different culture conditions as well as the selection of outcome parameters (morphological evaluation, viability assays, biochemical assays, metabolic assays) have a strong influence on the results of the experiments and the conclusions drawn from them. A primary example is the question of whether L-Dopa is toxic to dopaminergic neurons or whether it provides neurotrophic effects: In pure, neuronal-like cultures, L-Dopa provides toxicity, whereas in the presence of glial cells, it provides trophic effects when applied. The multitude of factors that influence the data generated from cell culture experiments indicates that in order to obtain clear-cut and unambiguous results, investigators need to choose their model carefully and are encouraged to verify their main results with different models.
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Affiliation(s)
- B H Falkenburger
- Department of Neurodegeneration and Restorative Research, Center of Neurology, University of Göttingen, Göttingen, Germany
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100
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Townsend M, Shankar GM, Mehta T, Walsh DM, Selkoe DJ. Effects of secreted oligomers of amyloid beta-protein on hippocampal synaptic plasticity: a potent role for trimers. J Physiol 2006; 572:477-92. [PMID: 16469784 PMCID: PMC1779683 DOI: 10.1113/jphysiol.2005.103754] [Citation(s) in RCA: 476] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Accepted: 02/07/2006] [Indexed: 01/08/2023] Open
Abstract
The accumulation of amyloid beta-protein (Abeta) in brain regions serving memory and cognition is a central pathogenic feature of Alzheimer's disease (AD). We have shown that small soluble oligomers of human Abeta that are naturally secreted by cultured cells inhibit hippocampal long-term potentiation (LTP) in vitro and in vivo and transiently impair the recall of a complex learned behaviour in rats. These results support the hypothesis that diffusible oligomers of Abeta initiate a synaptic dysfunction that may be an early event in AD. We now report detailed electrophysiological analyses that define conditions under which acute application of soluble Abeta inhibits hippocampal synaptic plasticity in wild-type mice. To ascertain which Abeta assemblies contribute to the impairment of LTP, we fractionated oligomers by size-exclusion chromatography and found that Abeta trimers fully inhibit LTP, whereas dimers and tetramers have an intermediate potency. Natural Abeta oligomers are sensitive to heat denaturation, primarily inhibit the induction phase of LTP, and cause a sustained impairment of LTP even after extensive washout. We observed no effects of Abeta oligomers on presynaptic vesicle release. LTP in juvenile mice is resistant to the effects of Abeta oligomers, as is brain-derived-neurotrophic-factor-induced LTP in adult hippocampus. We conclude that specific assemblies, particularly timers, of naturally secreted Abeta oligomers are potent and selective inhibitors of certain forms of hippocampal LTP.
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Affiliation(s)
- Matthew Townsend
- Department of Neurology, Harvard Medical School and Center for Neurologic Diseases, Brigham and Women's Hospital, Boston, MA 02115, USA
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