201
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Grønli J, Soulé J, Bramham CR. Sleep and protein synthesis-dependent synaptic plasticity: impacts of sleep loss and stress. Front Behav Neurosci 2014; 7:224. [PMID: 24478645 PMCID: PMC3896837 DOI: 10.3389/fnbeh.2013.00224] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Accepted: 12/23/2013] [Indexed: 01/08/2023] Open
Abstract
Sleep has been ascribed a critical role in cognitive functioning. Several lines of evidence implicate sleep in the consolidation of synaptic plasticity and long-term memory. Stress disrupts sleep while impairing synaptic plasticity and cognitive performance. Here, we discuss evidence linking sleep to mechanisms of protein synthesis-dependent synaptic plasticity and synaptic scaling. We then consider how disruption of sleep by acute and chronic stress may impair these mechanisms and degrade sleep function.
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Affiliation(s)
- Janne Grønli
- Department of Biological and Medical Psychology, University of Bergen Bergen, Norway ; Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital Bergen, Norway
| | - Jonathan Soulé
- Department of Biological and Medical Psychology, University of Bergen Bergen, Norway
| | - Clive R Bramham
- Department of Biomedicine and KG Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen Bergen, Norway
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202
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Tononi G, Cirelli C. Sleep and the price of plasticity: from synaptic and cellular homeostasis to memory consolidation and integration. Neuron 2014; 81:12-34. [PMID: 24411729 PMCID: PMC3921176 DOI: 10.1016/j.neuron.2013.12.025] [Citation(s) in RCA: 1233] [Impact Index Per Article: 123.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Sleep is universal, tightly regulated, and its loss impairs cognition. But why does the brain need to disconnect from the environment for hours every day? The synaptic homeostasis hypothesis (SHY) proposes that sleep is the price the brain pays for plasticity. During a waking episode, learning statistical regularities about the current environment requires strengthening connections throughout the brain. This increases cellular needs for energy and supplies, decreases signal-to-noise ratios, and saturates learning. During sleep, spontaneous activity renormalizes net synaptic strength and restores cellular homeostasis. Activity-dependent down-selection of synapses can also explain the benefits of sleep on memory acquisition, consolidation, and integration. This happens through the offline, comprehensive sampling of statistical regularities incorporated in neuronal circuits over a lifetime. This Perspective considers the rationale and evidence for SHY and points to open issues related to sleep and plasticity.
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Affiliation(s)
- Giulio Tononi
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA.
| | - Chiara Cirelli
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA.
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203
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Viola H, Ballarini F, Martínez MC, Moncada D. The tagging and capture hypothesis from synapse to memory. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 122:391-423. [PMID: 24484708 DOI: 10.1016/b978-0-12-420170-5.00013-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The synaptic tagging and capture theory (STC) was postulated by Frey and Morris in 1997 and provided a strong framework to explain how to achieve synaptic specificity and persistence of electrophysiological-induced plasticity changes. Ten years later, the same argument was applied on learning and memory models to explain the formation of long-term memories, resulting in the behavioral tagging hypothesis (BT). These hypotheses are able to explain how a weak event that induces transient changes in the brain can establish long-lasting phenomena through a tagging and capture process. In this framework, it was postulated that the weak event sets a tag that captures plasticity-related proteins/products (PRPs) synthesized by an independent strong event. The tagging and capture processes exhibit symmetry, and therefore, PRPs can be captured if they are synthesized either before or after the setting of the tag. In summary, the hypothesis provides a wide framework that gives a solid explanation of how lasting changes occur and how the interaction between different events leads to promotion, reinforcement, or impairment of such changes. In this chapter, we will summarize the postulates of STC hypothesis, the common features between synaptic plasticity and memory, as well as a detailed compilation of the findings supporting the existence of BT process. At the end, we pose some questions related to BT mechanism and LTM formation, which probably will be answered in the near future.
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Affiliation(s)
- Haydée Viola
- Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis", Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina; Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Fabricio Ballarini
- Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis", Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - María Cecilia Martínez
- Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis", Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Diego Moncada
- Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis", Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina; Neurophysiology of Learning and Memory Research Group, Leibniz-Institut für Neurobiologie, Magdeburg, Germany
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204
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Nonaka M, Fujii H, Kim R, Kawashima T, Okuno H, Bito H. Untangling the two-way signalling route from synapses to the nucleus, and from the nucleus back to the synapses. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130150. [PMID: 24298152 DOI: 10.1098/rstb.2013.0150] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
During learning and memory, it has been suggested that the coordinated electrical activity of hippocampal neurons translates information about the external environment into internal neuronal representations, which then are stored initially within the hippocampus and subsequently into other areas of the brain. A widely held hypothesis posits that synaptic plasticity is a key feature that critically modulates the triggering and the maintenance of such representations, some of which are thought to persist over time as traces or tags. However, the molecular and cell biological basis for these traces and tags has remained elusive. Here, we review recent findings that help clarify some of the molecular and cellular mechanisms critical for these events, by untangling a two-way signalling crosstalk route between the synapses and the neuronal soma. In particular, a detailed interrogation of the soma-to-synapse delivery of immediate early gene product Arc/Arg3.1, whose induction is triggered by heightened synaptic activity in many brain areas, teases apart an unsuspected 'inverse' synaptic tagging mechanism that likely contributes to maintaining the contrast of synaptic weight between strengthened and weak synapses within an active ensemble.
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Affiliation(s)
- Mio Nonaka
- Department of Neurochemistry, Graduate School of Medicine, University of Tokyo, , Bunkyo-ku, Tokyo 113-0033, Japan
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205
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Takeuchi T, Duszkiewicz AJ, Morris RGM. The synaptic plasticity and memory hypothesis: encoding, storage and persistence. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130288. [PMID: 24298167 DOI: 10.1098/rstb.2013.0288] [Citation(s) in RCA: 361] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The synaptic plasticity and memory hypothesis asserts that activity-dependent synaptic plasticity is induced at appropriate synapses during memory formation and is both necessary and sufficient for the encoding and trace storage of the type of memory mediated by the brain area in which it is observed. Criteria for establishing the necessity and sufficiency of such plasticity in mediating trace storage have been identified and are here reviewed in relation to new work using some of the diverse techniques of contemporary neuroscience. Evidence derived using optical imaging, molecular-genetic and optogenetic techniques in conjunction with appropriate behavioural analyses continues to offer support for the idea that changing the strength of connections between neurons is one of the major mechanisms by which engrams are stored in the brain.
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Affiliation(s)
- Tomonori Takeuchi
- Centre for Cognitive and Neural Systems, University of Edinburgh, , 1 George Square, Edinburgh EH8 9JZ, UK
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206
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Cheng X, Wu J, Geng M, Xiong J. Role of synaptic activity in the regulation of amyloid beta levels in Alzheimer's disease. Neurobiol Aging 2013; 35:1217-32. [PMID: 24368087 DOI: 10.1016/j.neurobiolaging.2013.11.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2012] [Revised: 11/03/2013] [Accepted: 11/24/2013] [Indexed: 01/27/2023]
Abstract
Alzheimer's disease (AD) is the most common form of dementia. Accumulation of amyloid-beta (Aβ) peptides is regarded as the critical component associated with AD pathogenesis, which is derived from the amyloid precursor protein (APP) cleavage. Recent studies suggest that synaptic activity is one of the most important factors that regulate Aβ levels. It has been found that synaptic activity facilitates APP internalization and influences APP cleavage. Glutamatergic, cholinergic, serotonergic, leptin, adrenergic, orexin, and gamma-amino butyric acid receptors, as well as the activity-regulated cytoskeleton-associated protein (Arc) are all involved in these processes. The present review summarizes the evidence for synaptic activity-modulated Aβ levels and the mechanisms underlying this regulation. Interestingly, the immediate early gene product Arc may also be the downstream signaling molecule of several receptors in the synaptic activity-modulated Aβ levels. Elucidating how Aβ levels are regulated by synaptic activity may provide new insights in both the understanding of the pathogenesis of AD and in the development of therapies to slow down the progression of AD.
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Affiliation(s)
- Xiaofang Cheng
- Department of Physiology, Third Military Medical University, Chongqing, China
| | - Jian Wu
- Department of Physiology, Third Military Medical University, Chongqing, China
| | - Miao Geng
- Institute of Geriatrics, General Hospital of Chinese PLA, Beijing, China
| | - Jiaxiang Xiong
- Department of Physiology, Third Military Medical University, Chongqing, China.
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207
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Nere A, Hashmi A, Cirelli C, Tononi G. Sleep-dependent synaptic down-selection (I): modeling the benefits of sleep on memory consolidation and integration. Front Neurol 2013; 4:143. [PMID: 24137153 PMCID: PMC3786405 DOI: 10.3389/fneur.2013.00143] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2013] [Accepted: 09/12/2013] [Indexed: 11/27/2022] Open
Abstract
Sleep can favor the consolidation of both procedural and declarative memories, promote gist extraction, help the integration of new with old memories, and desaturate the ability to learn. It is often assumed that such beneficial effects are due to the reactivation of neural circuits in sleep to further strengthen the synapses modified during wake or transfer memories to different parts of the brain. A different possibility is that sleep may benefit memory not by further strengthening synapses, but rather by renormalizing synaptic strength to restore cellular homeostasis after net synaptic potentiation in wake. In this way, the sleep-dependent reactivation of neural circuits could result in the competitive down-selection of synapses that are activated infrequently and fit less well with the overall organization of memories. By using computer simulations, we show here that synaptic down-selection is in principle sufficient to explain the beneficial effects of sleep on the consolidation of procedural and declarative memories, on gist extraction, and on the integration of new with old memories, thereby addressing the plasticity-stability dilemma.
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Affiliation(s)
- Andrew Nere
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison , Madison, WI , USA
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208
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209
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Truini A, Garcia-Larrea L, Cruccu G. Reappraising neuropathic pain in humans--how symptoms help disclose mechanisms. Nat Rev Neurol 2013; 9:572-82. [PMID: 24018479 DOI: 10.1038/nrneurol.2013.180] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Neuropathic pain--that is, pain arising directly from a lesion or disease that affects the somatosensory system--is a common clinical problem, and typically causes patients intense distress. Patients with neuropathic pain have sensory abnormalities on clinical examination and experience pain of diverse types, some spontaneous and others provoked. Spontaneous pain typically manifests as ongoing burning pain or paroxysmal electric shock-like sensations. Provoked pain includes pain induced by various stimuli or even gentle brushing (dynamic mechanical allodynia). Recent clinical and neurophysiological studies suggest that the various pain types arise through distinct pathophysiological mechanisms. Ongoing burning pain primarily reflects spontaneous hyperactivity in nociceptive-fibre pathways, originating from 'irritable' nociceptors, regenerating nerve sprouts or denervated central neurons. Paroxysmal sensations can be caused by several mechanisms; for example, electric shock-like sensations probably arise from high-frequency bursts generated in demyelinated non-nociceptive Aβ fibres. Most human and animal findings suggest that brush-evoked allodynia originates from Aβ fibres projecting onto previously sensitized nociceptive neurons in the dorsal horn, with additional contributions from plastic changes in the brainstem and thalamus. Here, we propose that the emerging mechanism-based approach to the study of neuropathic pain might aid the tailoring of therapy to the individual patient, and could be useful for drug development.
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Affiliation(s)
- Andrea Truini
- Department of Neurology and Psychiatry, Sapienza University, Viale Università 30, 00185 Rome, Italy
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210
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Mikuni T, Uesaka N, Okuno H, Hirai H, Deisseroth K, Bito H, Kano M. Arc/Arg3.1 is a postsynaptic mediator of activity-dependent synapse elimination in the developing cerebellum. Neuron 2013; 78:1024-35. [PMID: 23791196 PMCID: PMC3773328 DOI: 10.1016/j.neuron.2013.04.036] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/23/2013] [Indexed: 11/30/2022]
Abstract
Neural circuits are shaped by activity-dependent elimination of redundant synapses during postnatal development. In many systems, postsynaptic activity is known to be crucial, but the precise mechanisms remain elusive. Here, we report that the immediate early gene Arc/Arg3.1 mediates elimination of surplus climbing fiber (CF) to Purkinje cell (PC) synapses in the developing cerebellum. CF synapse elimination was accelerated when activity of channelrhodopsin-2-expressing PCs was elevated by 2-day photostimulation. This acceleration was suppressed by PC-specific knockdown of either the P/Q-type voltage-dependent Ca(2+) channels (VDCCs) or Arc. PC-specific Arc knockdown had no appreciable effect until around postnatal day 11 but significantly impaired CF synapse elimination thereafter, leaving redundant CF terminals on PC somata. The effect of Arc knockdown was occluded by simultaneous knockdown of P/Q-type VDCCs in PCs. We conclude that Arc mediates the final stage of CF synapse elimination downstream of P/Q-type VDCCs by removing CF synapses from PC somata.
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Affiliation(s)
- Takayasu Mikuni
- Department of Neurophysiology, Graduate School of Medicine, the University of Tokyo, Tokyo 113-0033, Japan
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211
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Siddoway B, Hou H, Xia H. Molecular mechanisms of homeostatic synaptic downscaling. Neuropharmacology 2013; 78:38-44. [PMID: 23911745 DOI: 10.1016/j.neuropharm.2013.07.009] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 07/04/2013] [Accepted: 07/05/2013] [Indexed: 11/28/2022]
Abstract
Homeostatic synaptic downscaling is a negative feedback response to chronic elevated network activity to reduce the firing rate of neurons. This form of synaptic plasticity decreases the strength of individual synapses to the same proportion, or in a multiplicative manner. Because of this, synaptic downscaling has been hypothesized to counter the potential run-away excitation due to Hebbian type of long term potentiation (LTP), while preserving relative synaptic weight encoded in individual synapses and thus memory information. In this article, we will review the current knowledge on the signaling and molecular mechanisms of synaptic downscaling. Specifically, we focus on three general areas. First the functional roles of several immediate early genes such as Plk2, Homer1a, Arc and Narp are discussed. Secondly, we examine the current knowledge on the regulation of synaptic protein levels by ubiquitination and transcriptional repression in synaptic downscaling. Thirdly, we review the dynamics of signaling molecules such as kinases and phosphatases critical for synaptic downscaling, and their regulation of synaptic scaffolding proteins. Finally we briefly discuss the heterogeneity of homeostatic synaptic downscaling mechanisms. This article is part of the Special Issue entitled 'Homeostatic Synaptic Plasticity'.
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Affiliation(s)
- Benjamin Siddoway
- Neuroscience Center of Excellence, Louisiana State University Health Science Center, New Orleans, LA 70112, USA
| | - Hailong Hou
- Neuroscience Center of Excellence, Louisiana State University Health Science Center, New Orleans, LA 70112, USA
| | - Houhui Xia
- Neuroscience Center of Excellence, Louisiana State University Health Science Center, New Orleans, LA 70112, USA.
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212
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Bello-Medina PC, Sánchez-Carrasco L, González-Ornelas NR, Jeffery KJ, Ramírez-Amaya V. Differential effects of spaced vs. massed training in long-term object-identity and object-location recognition memory. Behav Brain Res 2013; 250:102-13. [DOI: 10.1016/j.bbr.2013.04.047] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 04/19/2013] [Accepted: 04/23/2013] [Indexed: 01/17/2023]
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213
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Kawashima T, Kitamura K, Suzuki K, Nonaka M, Kamijo S, Takemoto-Kimura S, Kano M, Okuno H, Ohki K, Bito H. Functional labeling of neurons and their projections using the synthetic activity–dependent promoter E-SARE. Nat Methods 2013; 10:889-95. [DOI: 10.1038/nmeth.2559] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2012] [Accepted: 06/18/2013] [Indexed: 12/23/2022]
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214
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Takao K, Kobayashi K, Hagihara H, Ohira K, Shoji H, Hattori S, Koshimizu H, Umemori J, Toyama K, Nakamura HK, Kuroiwa M, Maeda J, Atsuzawa K, Esaki K, Yamaguchi S, Furuya S, Takagi T, Walton NM, Hayashi N, Suzuki H, Higuchi M, Usuda N, Suhara T, Nishi A, Matsumoto M, Ishii S, Miyakawa T. Deficiency of schnurri-2, an MHC enhancer binding protein, induces mild chronic inflammation in the brain and confers molecular, neuronal, and behavioral phenotypes related to schizophrenia. Neuropsychopharmacology 2013; 38:1409-25. [PMID: 23389689 PMCID: PMC3682135 DOI: 10.1038/npp.2013.38] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Schnurri-2 (Shn-2), an nuclear factor-κB site-binding protein, tightly binds to the enhancers of major histocompatibility complex class I genes and inflammatory cytokines, which have been shown to harbor common variant single-nucleotide polymorphisms associated with schizophrenia. Although genes related to immunity are implicated in schizophrenia, there has been no study showing that their mutation or knockout (KO) results in schizophrenia. Here, we show that Shn-2 KO mice have behavioral abnormalities that resemble those of schizophrenics. The mutant brain demonstrated multiple schizophrenia-related phenotypes, including transcriptome/proteome changes similar to those of postmortem schizophrenia patients, decreased parvalbumin and GAD67 levels, increased theta power on electroencephalograms, and a thinner cortex. Dentate gyrus granule cells failed to mature in mutants, a previously proposed endophenotype of schizophrenia. Shn-2 KO mice also exhibited mild chronic inflammation of the brain, as evidenced by increased inflammation markers (including GFAP and NADH/NADPH oxidase p22 phox), and genome-wide gene expression patterns similar to various inflammatory conditions. Chronic administration of anti-inflammatory drugs reduced hippocampal GFAP expression, and reversed deficits in working memory and nest-building behaviors in Shn-2 KO mice. These results suggest that genetically induced changes in immune system can be a predisposing factor in schizophrenia.
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Affiliation(s)
- Keizo Takao
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan,Section of Behavior Patterns, Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, Okazaki, Japan,Japan Science and Technology Agency, CREST, Kawaguchi, Japan
| | - Katsunori Kobayashi
- Japan Science and Technology Agency, CREST, Kawaguchi, Japan,Department of Pharmacology, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Hideo Hagihara
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan,Japan Science and Technology Agency, CREST, Kawaguchi, Japan
| | - Koji Ohira
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan,Japan Science and Technology Agency, CREST, Kawaguchi, Japan
| | - Hirotaka Shoji
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan,Japan Science and Technology Agency, CREST, Kawaguchi, Japan
| | - Satoko Hattori
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan,Japan Science and Technology Agency, CREST, Kawaguchi, Japan
| | - Hisatsugu Koshimizu
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan,Japan Science and Technology Agency, CREST, Kawaguchi, Japan
| | - Juzoh Umemori
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan,Japan Science and Technology Agency, CREST, Kawaguchi, Japan
| | - Keiko Toyama
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan,Japan Science and Technology Agency, CREST, Kawaguchi, Japan
| | - Hironori K Nakamura
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan,Japan Science and Technology Agency, CREST, Kawaguchi, Japan
| | - Mahomi Kuroiwa
- Japan Science and Technology Agency, CREST, Kawaguchi, Japan,Department of Pharmacology, Kurume University School of Medicine, Kurume, Japan
| | - Jun Maeda
- Molecular Neuroimaging Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Kimie Atsuzawa
- Department of Anatomy II, Fujita Health University School of Medicine, Toyoake, Japan
| | - Kayoko Esaki
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Shun Yamaguchi
- Division of Morphological Neuroscience, Gifu University Graduate School of Medicine, Gifu, Japan,Japan Science and Technology Agency, PRESTO, Kawaguchi, Japan
| | - Shigeki Furuya
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Tsuyoshi Takagi
- RIKEN Tsukuba Institute, Tsukuba, Japan,Institute for Developmental Research, Aichi Human Service Center, Kasugai, Japan
| | - Noah M Walton
- Astellas Research Institute of America LLC, Skokie, IL, USA
| | - Nobuhiro Hayashi
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Tokyo, Japan
| | - Hidenori Suzuki
- Japan Science and Technology Agency, CREST, Kawaguchi, Japan,Department of Pharmacology, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Makoto Higuchi
- Molecular Neuroimaging Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Nobuteru Usuda
- Department of Anatomy II, Fujita Health University School of Medicine, Toyoake, Japan
| | - Tetsuya Suhara
- Molecular Neuroimaging Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Akinori Nishi
- Japan Science and Technology Agency, CREST, Kawaguchi, Japan,Department of Pharmacology, Kurume University School of Medicine, Kurume, Japan
| | | | - Shunsuke Ishii
- Japan Science and Technology Agency, PRESTO, Kawaguchi, Japan
| | - Tsuyoshi Miyakawa
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan,Section of Behavior Patterns, Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, Okazaki, Japan,Japan Science and Technology Agency, CREST, Kawaguchi, Japan,Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake 470-1192, Japan. Tel: +81 562 93 9375, Fax: +81 562 92 5328, E-mail:
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215
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Kim R, Okuno H, Bito H. Deciphering the molecular rules governing synaptic targeting of the memory-related protein Arc. Commun Integr Biol 2013; 5:496-8. [PMID: 23739267 PMCID: PMC3502215 DOI: 10.4161/cib.20853] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Neurons express new gene transcripts and proteins upon receiving synaptic inputs, and these events are essential for achieving proper neuronal wiring, adequate synaptic plasticity, and updatable memory. However, the biological impact of new gene expression on input-specific synaptic potentiation remains largely elusive, in part because the cell biological and biochemical mechanisms for synaptic targeting of newly synthesized proteins has remained obscure. A new study investigating the targeting of the memory related protein Arc from the soma to the synapses teases apart a novel “inverse” synaptic tagging mechanism that enables Arc to specifically target the un-potentiated synapses, thereby helping to maintain the contrast of synaptic weight between strengthened and weak synapses.
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Affiliation(s)
- Ryang Kim
- Department of Neurochemistry; The University of Tokyo Graduate School of Medicine; Bunkyo-ku, Tokyo Japan
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216
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Lee KFH, Soares C, Béïque JC. Tuning into diversity of homeostatic synaptic plasticity. Neuropharmacology 2013; 78:31-7. [PMID: 23541721 DOI: 10.1016/j.neuropharm.2013.03.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 02/19/2013] [Accepted: 03/19/2013] [Indexed: 10/27/2022]
Abstract
Neurons are endowed with the remarkable ability to integrate activity levels over time and tune their excitability such that action potential firing is maintained within a computationally optimal range. These feedback mechanisms, collectively referred to as "homeostatic plasticity", enable neurons to respond and adapt to prolonged alterations in neuronal activity by regulating several determinants of cellular excitability. Perhaps the best-characterized of these homeostatic responses involves the regulation of excitatory glutamatergic transmission. This homeostatic synaptic plasticity (HSP) operates bidirectionally, thus providing a means for neurons to tune cellular excitability in response to either elevations or reductions in net activity. The last decade has seen rapid growth in interest and efforts to understand the mechanistic underpinnings of HSP in part because of the theoretical stabilization that HSP confers to neural network function. Since the initial reports describing HSP in central neurons, innovations in experimental approaches have permitted the mechanistic dissection of this cellular adaptive response and, as a result, key advances have been made in our understanding of the cellular and molecular basis of HSP. Here, we review recent evidence that outline the presence of distinct forms of HSP at excitatory glutamatergic synapses which operate at different sub-cellular levels. We further present theoretical considerations on the potential computational roles afforded by local, synapse-specific homeostatic regulation. This article is part of the Special Issue entitled 'Homeostatic Synaptic Plasticity'.
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Affiliation(s)
- Kevin F H Lee
- Neuroscience Graduate Program, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada; Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Cary Soares
- Neuroscience Graduate Program, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada; Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Jean-Claude Béïque
- Centre for Stroke Recovery, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada; Centre for Neural Dynamics, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada; Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada.
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217
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Sustained transcription of the immediate early gene Arc in the dentate gyrus after spatial exploration. J Neurosci 2013; 33:1631-9. [PMID: 23345235 DOI: 10.1523/jneurosci.2916-12.2013] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
After spatial exploration in rats, Arc mRNA is expressed in ∼2% of dentate gyrus (DG) granule cells, and this proportion of Arc-positive neurons remains stable for ∼8 h. This long-term presence of Arc mRNA following behavior is not observed in hippocampal CA1 pyramidal cells. We report here that in rats ∼50% of granule cells with cytoplasmic Arc mRNA, induced some hours previously during exploration, also show Arc expression in the nucleus. This suggests that recent transcription can occur long after the exploration behavior that elicited it. To confirm that the delayed nuclear Arc expression was indeed recent transcription, Actinomycin D was administered immediately after exploration. This treatment resulted in inhibition of recent Arc expression both when evaluated shortly after exploratory behavior as well as after longer time intervals. Together, these data demonstrate a unique kinetic profile for Arc transcription in hippocampal granule neurons following behavior that is not observed in other cell types. Among a number of possibilities, this sustained transcription may provide a mechanism that ensures that the synaptic connection weights in the sparse population of granule cells recruited during a given behavioral event are able to be modified.
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218
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The reduced cochlear output and the failure to adapt the central auditory response causes tinnitus in noise exposed rats. PLoS One 2013; 8:e57247. [PMID: 23516401 PMCID: PMC3596376 DOI: 10.1371/journal.pone.0057247] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 01/18/2013] [Indexed: 01/15/2023] Open
Abstract
Tinnitus is proposed to be caused by decreased central input from the cochlea, followed by increased spontaneous and evoked subcortical activity that is interpreted as compensation for increased responsiveness of central auditory circuits. We compared equally noise exposed rats separated into groups with and without tinnitus for differences in brain responsiveness relative to the degree of deafferentation in the periphery. We analyzed (1) the number of CtBP2/RIBEYE-positive particles in ribbon synapses of the inner hair cell (IHC) as a measure for deafferentation; (2) the fine structure of the amplitudes of auditory brainstem responses (ABR) reflecting differences in sound responses following decreased auditory nerve activity and (3) the expression of the activity-regulated gene Arc in the auditory cortex (AC) to identify long-lasting central activity following sensory deprivation. Following moderate trauma, 30% of animals exhibited tinnitus, similar to the tinnitus prevalence among hearing impaired humans. Although both tinnitus and no-tinnitus animals exhibited a reduced ABR wave I amplitude (generated by primary auditory nerve fibers), IHCs ribbon loss and high-frequency hearing impairment was more severe in tinnitus animals, associated with significantly reduced amplitudes of the more centrally generated wave IV and V and less intense staining of Arc mRNA and protein in the AC. The observed severe IHCs ribbon loss, the minimal restoration of ABR wave size, and reduced cortical Arc expression suggest that tinnitus is linked to a failure to adapt central circuits to reduced cochlear input.
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219
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Jungenitz T, Radic T, Jedlicka P, Schwarzacher SW. High-frequency stimulation induces gradual immediate early gene expression in maturing adult-generated hippocampal granule cells. ACTA ACUST UNITED AC 2013; 24:1845-57. [PMID: 23425888 DOI: 10.1093/cercor/bht035] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Increasing evidence shows that adult neurogenesis of hippocampal granule cells is advantageous for learning and memory. We examined at which stage of structural maturation and age new granule cells can be activated by strong synaptic stimulation. High-frequency stimulation of the perforant pathway in urethane-anesthetized rats elicited expression of the immediate early genes c-fos, Arc, zif268 and pCREB133 in almost 100% of mature, calbindin-positive granule cells. In contrast, it failed to induce immediate early gene expression in immature doublecortin-positive granule cells. Furthermore, doublecortin-positive neurons did not react with c-fos or Arc expression to mild theta-burst stimulation or novel environment exposure. Endogenous expression of pCREB133 was increasingly present in young cells with more elaborated dendrites, revealing a close correlation to structural maturation. Labeling with bromodeoxyuridine revealed cell age dependence of stimulation-induced c-fos, Arc and zif268 expression, with only a few cells reacting at 21 days, but with up to 75% of cells activated at 35-77 days of cell age. Our results indicate an increasing synaptic integration of maturing granule cells, starting at 21 days of cell age, but suggest a lack of ability to respond to activation with synaptic potentiation on the transcriptional level as long as immature cells express doublecortin.
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Affiliation(s)
- Tassilo Jungenitz
- Institute of Clinical Neuroanatomy, Goethe-University Frankfurt, NeuroScience Center, D-60590 Frankfurt am Main, Germany
| | - Tijana Radic
- Institute of Clinical Neuroanatomy, Goethe-University Frankfurt, NeuroScience Center, D-60590 Frankfurt am Main, Germany
| | - Peter Jedlicka
- Institute of Clinical Neuroanatomy, Goethe-University Frankfurt, NeuroScience Center, D-60590 Frankfurt am Main, Germany
| | - Stephan W Schwarzacher
- Institute of Clinical Neuroanatomy, Goethe-University Frankfurt, NeuroScience Center, D-60590 Frankfurt am Main, Germany
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220
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Cao C, Rioult-Pedotti MS, Migani P, Yu CJ, Tiwari R, Parang K, Spaller MR, Goebel DJ, Marshall J. Impairment of TrkB-PSD-95 signaling in Angelman syndrome. PLoS Biol 2013; 11:e1001478. [PMID: 23424281 PMCID: PMC3570550 DOI: 10.1371/journal.pbio.1001478] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 01/02/2013] [Indexed: 11/19/2022] Open
Abstract
Brain-derived neurotrophic factor signaling is defective in Angelman syndrome and can be rescued by disruption of Arc/PSD95 binding. Angelman syndrome (AS) is a neurodevelopment disorder characterized by severe cognitive impairment and a high rate of autism. AS is caused by disrupted neuronal expression of the maternally inherited Ube3A ubiquitin protein ligase, required for the proteasomal degradation of proteins implicated in synaptic plasticity, such as the activity-regulated cytoskeletal-associated protein (Arc/Arg3.1). Mice deficient in maternal Ube3A express elevated levels of Arc in response to synaptic activity, which coincides with severely impaired long-term potentiation (LTP) in the hippocampus and deficits in learning behaviors. In this study, we sought to test whether elevated levels of Arc interfere with brain-derived neurotrophic factor (BDNF) TrkB receptor signaling, which is known to be essential for both the induction and maintenance of LTP. We report that TrkB signaling in the AS mouse is defective, and show that reduction of Arc expression to control levels rescues the signaling deficits. Moreover, the association of the postsynaptic density protein PSD-95 with TrkB is critical for intact BDNF signaling, and elevated levels of Arc were found to impede PSD-95/TrkB association. In Ube3A deficient mice, the BDNF-induced recruitment of PSD-95, as well as PLCγ and Grb2-associated binder 1 (Gab1) with TrkB receptors was attenuated, resulting in reduced activation of PLCγ-α-calcium/calmodulin-dependent protein kinase II (CaMKII) and PI3K-Akt, but leaving the extracellular signal-regulated kinase (Erk) pathway intact. A bridged cyclic peptide (CN2097), shown by nuclear magnetic resonance (NMR) studies to uniquely bind the PDZ1 domain of PSD-95 with high affinity, decreased the interaction of Arc with PSD-95 to restore BDNF-induced TrkB/PSD-95 complex formation, signaling, and facilitate the induction of LTP in AS mice. We propose that the failure of TrkB receptor signaling at synapses in AS is directly linked to elevated levels of Arc associated with PSD-95 and PSD-95 PDZ-ligands may represent a promising approach to reverse cognitive dysfunction. Angelman syndrome (AS) is a debilitating neurological disorder caused by a dysfunctional Ube3A gene. Most children with AS exhibit developmental delay, movement disorders, speech impairment, and often autistic features. The Ube3A enzyme normally regulates the degradation of the synaptic protein Arc, and in its absence the resulting elevated levels of Arc weaken synaptic contacts, making it difficult to generate long-term potentiation (LTP) and to process and store memory. In this study, we show that increased levels of Arc disrupt brain-derived neurotrophic factor (BDNF) signaling through the TrkB receptor (which is important for both the induction and maintenance of LTP). We find that the association of the postsynaptic density protein PSD-95 with TrkB is critical for intact BDNF signaling, and that the high levels of Arc in AS interfere with BDNF-induced recruitment of postsynaptic density protein-95 (PSD-95) and other effectors to TrkB. By disrupting the interaction between Arc and PSD-95 with the novel cyclic peptidomimetic compound CN2097, we were able to restore BDNF signaling and improve the induction of LTP in a mouse model of AS. We propose that the disruption of TrkB receptor signaling at synapses contributes to the cognitive dysfunction that occurs in Angelman syndrome.
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Affiliation(s)
- Cong Cao
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, Rhode Island, United States of America
- Institute of Neuroscience, The Second Affiliated Hospital of Soochow University, Soochow University, Suzhou, China
| | - Mengia S. Rioult-Pedotti
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, Rhode Island, United States of America
| | - Paolo Migani
- Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Ancona, Italy
| | - Crystal J. Yu
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, Rhode Island, United States of America
| | - Rakesh Tiwari
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island, United States of America
| | - Keykavous Parang
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island, United States of America
| | - Mark R. Spaller
- Norris Cotton Cancer Center and Department of Pharmacology and Toxicology, Dartmouth Medical School, Lebanon, New Hampshire, United States of America
| | - Dennis J. Goebel
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan, United States of America
- * E-mail: (DJG); (JM)
| | - John Marshall
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, Rhode Island, United States of America
- * E-mail: (DJG); (JM)
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221
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Stern SA, Alberini CM. Mechanisms of memory enhancement. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2013; 5:37-53. [PMID: 23151999 PMCID: PMC3527655 DOI: 10.1002/wsbm.1196] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The ongoing quest for memory enhancement is one that grows necessary as the global population increasingly ages. The extraordinary progress that has been made in the past few decades elucidating the underlying mechanisms of how long-term memories are formed has provided insight into how memories might also be enhanced. Capitalizing on this knowledge, it has been postulated that targeting many of the same mechanisms, including CREB activation, AMPA/NMDA receptor trafficking, neuromodulation (e.g., via dopamine, adrenaline, cortisol, or acetylcholine) and metabolic processes (e.g., via glucose and insulin) may all lead to the enhancement of memory. These and other mechanisms and/or approaches have been tested via genetic or pharmacological methods in animal models, and several have been investigated in humans as well. In addition, a number of behavioral methods, including exercise and reconsolidation, may also serve to strengthen and enhance memories. By utilizing this information and continuing to investigate these promising avenues, memory enhancement may indeed be achieved in the future.
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Affiliation(s)
- Sarah A. Stern
- Friedman Brain Institute, Graduate School of Biological Sciences, Mount Sinai School of Memories
- Center for Neural Science, New York University
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222
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Abstract
Structural changes in brain circuits active during learning are thought to be important for long-term memory storage. If these changes support long-term information storage, they might be expected to be present at distant time points after learning, as well as to be specific to the circuit activated with learning, and sensitive to the contingencies of the behavioral paradigm. Here, we show such changes in the hippocampus as a result of contextual fear conditioning. There were significantly fewer spines specifically on active neurons of fear-conditioned mice. This spine loss did not occur in homecage mice or in mice exposed to the training context alone. Mice exposed to unpaired shocks showed a generalized reduction in spines. These learning-related changes in spine density could reflect a direct mechanism of encoding or alternately could reflect a compensatory adaptation to previously described enhancement in transmission due to glutamate receptor insertion.
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223
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Yoshioka W, Endo N, Kurashige A, Haijima A, Endo T, Shibata T, Nishiyama R, Kakeyama M, Tohyama C. Fluorescence laser microdissection reveals a distinct pattern of gene activation in the mouse hippocampal region. Sci Rep 2012; 2:783. [PMID: 23136640 PMCID: PMC3491666 DOI: 10.1038/srep00783] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 10/10/2012] [Indexed: 02/06/2023] Open
Abstract
A histoanatomical context is imperative in an analysis of gene expression in a cell in a tissue to elucidate physiological function of the cell. In this study, we made technical advances in fluorescence laser microdissection (LMD) in combination with the absolute quantification of small amounts of mRNAs from a region of interest (ROI) in fluorescence-labeled tissue sections. We demonstrate that our fluorescence LMD-RTqPCR method has three orders of dynamic range, with the lower limit of ROI-size corresponding to a single cell. The absolute quantification of the expression levels of the immediate early genes in an ROI equivalent to a few hundred neurons in the hippocampus revealed that mice transferred from their home cage to a novel environment have distinct activation profiles in the hippocampal regions (CA1, CA3, and DG) and that the gene expression pattern in CA1, but not in the other regions, follows a power law distribution.
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Affiliation(s)
- Wataru Yoshioka
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Nozomi Endo
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Akie Kurashige
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Asahi Haijima
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- Current address: Department of Integrative Physiology, Gunma University Graduate School of Medicine, Gunma 371-8511, Japan
| | - Toshihiro Endo
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Toshiyuki Shibata
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- Department of Human Ecology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Ryutaro Nishiyama
- Research/Clinical/Industrial Division, Leica Microsystems K.K., Tokyo 108-0072, Japan
| | - Masaki Kakeyama
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Chiharu Tohyama
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
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224
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Wang H, Zhuo M. Group I metabotropic glutamate receptor-mediated gene transcription and implications for synaptic plasticity and diseases. Front Pharmacol 2012; 3:189. [PMID: 23125836 PMCID: PMC3485740 DOI: 10.3389/fphar.2012.00189] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 10/11/2012] [Indexed: 12/05/2022] Open
Abstract
Stimulation of group I metabotropic glutamate receptors (mGluRs) initiates a wide variety of signaling pathways. Group I mGluR activation can regulate gene expression at both translational and transcriptional levels, and induces translation or transcription-dependent synaptic plastic changes in neurons. The group I mGluR-mediated translation-dependent neural plasticity has been well reviewed. In this review, we will highlight group I mGluR-induced gene transcription and its role in synaptic plasticity. The signaling pathways (PKA, CaMKs, and MAPKs) which have been shown to link group I mGluRs to gene transcription, the relevant transcription factors (CREB and NF-κB), and target proteins (FMRP and ARC) will be documented. The significance and future direction for characterizing group I mGluR-mediated gene transcription in fragile X syndrome, schizophrenia, drug addiction, and other neurological disorders will also be discussed.
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Affiliation(s)
- Hansen Wang
- Department of Physiology, Faculty of Medicine, University of Toronto Toronto, ON, Canada
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225
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Yamasaki Y, Hashikawa K, Matsuki N, Nomura H. Off-line Arc transcription in active ensembles during fear memory retrieval. Eur J Neurosci 2012; 36:3451-7. [PMID: 22928932 DOI: 10.1111/j.1460-9568.2012.08269.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neural activity and de novo protein synthesis during a rest period following memory retrieval in the amygdala is necessary for stabilization of reactivated fear memory. Arc/Arg3.1 (Arc) expression is regulated by neural activity and is a critical protein for memory reconsolidation. However, it remains unclear whether memory retrieval alters Arc transcription during subsequent rest. In this study, the populations of mouse lateral amygdala neurons that transcribe Arc during memory retrieval and at rest were detected using Arc cellular compartment analysis of temporal activity by fluorescence in situ hybridization (Arc catFISH). Results demonstrated that memory retrieval alters the composition of neuronal populations, which activate Arc transcription during subsequent rest. Approximately 50% of neurons that transcribe Arc at subsequent rest, transcribed Arc during memory retrieval, whereas only approximately 10% of neurons that transcribed Arc during a rest period prior to memory retrieval transcribe Arc during memory retrieval. In contrast, re-exposure to the chamber induced less preferential Arc transcription in latent inhibited mice that received shocks but recalled less conditioned fear. Taken together, these findings indicate that neuronal subpopulations activated during fear memory retrieval preferentially transcribe Arc during subsequent rest in the lateral amygdala. This preferential Arc transcription may contribute to memory reconsolidation.
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Affiliation(s)
- Yoshiko Yamasaki
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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226
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Whalley K. ARC plays inverse tag at synapses. Nat Rev Neurosci 2012; 13:449. [DOI: 10.1038/nrn3272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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227
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Network, cellular, and molecular mechanisms underlying long-term memory formation. Curr Top Behav Neurosci 2012; 15:73-115. [PMID: 22976275 DOI: 10.1007/7854_2012_229] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The neural network stores information through activity-dependent synaptic plasticity that occurs in populations of neurons. Persistent forms of synaptic plasticity may account for long-term memory storage, and the most salient forms are the changes in the structure of synapses. The theory proposes that encoding should use a sparse code and evidence suggests that this can be achieved through offline reactivation or by sparse initial recruitment of the network units. This idea implies that in some cases the neurons that underwent structural synaptic plasticity might be a subpopulation of those originally recruited; However, it is not yet clear whether all the neurons recruited during acquisition are the ones that underwent persistent forms of synaptic plasticity and responsible for memory retrieval. To determine which neural units underlie long-term memory storage, we need to characterize which are the persistent forms of synaptic plasticity occurring in these neural ensembles and the best hints so far are the molecular signals underlying structural modifications of the synapses. Structural synaptic plasticity can be achieved by the activity of various signal transduction pathways, including the NMDA-CaMKII and ACh-MAPK. These pathways converge with the Rho family of GTPases and the consequent ERK 1/2 activation, which regulates multiple cellular functions such as protein translation, protein trafficking, and gene transcription. The most detailed explanation may come from models that allow us to determine the contribution of each piece of this fascinating puzzle that is the neuron and the neural network.
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