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Lee YS. Genes and signaling pathways involved in memory enhancement in mutant mice. Mol Brain 2014; 7:43. [PMID: 24894914 PMCID: PMC4050447 DOI: 10.1186/1756-6606-7-43] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 05/27/2014] [Indexed: 11/10/2022] Open
Abstract
Mutant mice have been used successfully as a tool for investigating the mechanisms of memory at multiple levels, from genes to behavior. In most cases, manipulating a gene expressed in the brain impairs cognitive functions such as memory and their underlying cellular mechanisms, including synaptic plasticity. However, a remarkable number of mutations have been shown to enhance memory in mice. Understanding how to improve a system provides valuable insights into how the system works under normal conditions, because this involves understanding what the crucial components are. Therefore, more can be learned about the basic mechanisms of memory by studying mutant mice with enhanced memory. This review will summarize the genes and signaling pathways that are altered in the mutants with enhanced memory, as well as their roles in synaptic plasticity. Finally, I will discuss how knowledge of memory-enhancing mechanisms could be used to develop treatments for cognitive disorders associated with impaired plasticity.
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Affiliation(s)
- Yong-Seok Lee
- Department of Life Science, College of Natural Science, Chung-Ang University, Seoul 156-756, Republic of Korea.
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Merlo E, Milton AL, Goozée ZY, Theobald DE, Everitt BJ. Reconsolidation and extinction are dissociable and mutually exclusive processes: behavioral and molecular evidence. J Neurosci 2014; 34:2422-31. [PMID: 24523532 PMCID: PMC3921417 DOI: 10.1523/jneurosci.4001-13.2014] [Citation(s) in RCA: 177] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 12/20/2013] [Accepted: 12/27/2013] [Indexed: 11/21/2022] Open
Abstract
Memory persistence is critically influenced by retrieval. In rats, a single presentation of a conditioned fear stimulus induces memory reconsolidation and fear memory persistence, while repeated fear cue presentations result in loss of fear through extinction. These two opposite behavioral outcomes are operationally linked by the number of cue presentations at memory retrieval. However, the behavioral properties and mechanistic determinants of the transition have not yet been explored; in particular, whether reconsolidation and extinction processes coexist or are mutually exclusive, depending on the exposure to non-reinforced retrieval events. We characterized both behaviorally and molecularly the transition from reconsolidation to extinction of conditioned fear and showed that an increase in calcineurin (CaN) in the basolateral amygdala (BLA) supports the shift from fear maintenance to fear inhibition. Gradually increasing the extent of retrieval induces a gradual decrease in freezing responses to the conditioned stimulus and a gradual increase in amygdala CaN level. This newly synthesized CaN is required for the extinction, but not the reconsolidation, of conditioned fear. During the transition from reconsolidation to extinction, we have revealed an insensitive state of the fear memory where NMDA-type glutamate receptor agonist and antagonist drugs are unable either to modulate CaN levels in the BLA or alter the reconsolidation or extinction processes. Together, our data indicate both that reconsolidation and extinction are mutually exclusive processes and also reveal the presence of a transitional, or "limbo," state of the original memory between these two alternative outcomes of fear memory retrieval, when neither process is engaged.
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Affiliation(s)
- Emiliano Merlo
- Behavioural and Clinical Neuroscience Institute and Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom
| | - Amy L. Milton
- Behavioural and Clinical Neuroscience Institute and Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom
| | - Zara Y. Goozée
- Behavioural and Clinical Neuroscience Institute and Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom
| | - David E. Theobald
- Behavioural and Clinical Neuroscience Institute and Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom
| | - Barry J. Everitt
- Behavioural and Clinical Neuroscience Institute and Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom
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Veyrac A, Besnard A, Caboche J, Davis S, Laroche S. The transcription factor Zif268/Egr1, brain plasticity, and memory. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 122:89-129. [PMID: 24484699 DOI: 10.1016/b978-0-12-420170-5.00004-0] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The capacity to remember our past experiences and organize our future draws on a number of cognitive processes that allow our brain to form and store neural representations that can be recalled and updated at will. In the brain, these processes require mechanisms of neural plasticity in the activated circuits, brought about by cellular and molecular changes within the neurons activated during learning. At the cellular level, a wealth of experimental data accumulated in recent years provides evidence that signaling from synapses to nucleus and the rapid regulation of the expression of immediate early genes encoding inducible, regulatory transcription factors is a key step in the mechanisms underlying synaptic plasticity and the modification of neural networks required for the laying down of memories. In the activated neurons, these transcriptional events are thought to mediate the activation of selective gene programs and subsequent synthesis of proteins, leading to stable functional and structural remodeling of the activated networks, so that the memory can later be reactivated upon recall. Over the past few decades, novel insights have been gained in identifying key transcriptional regulators that can control the genomic response of synaptically activated neurons. Here, as an example of this approach, we focus on one such activity-dependent transcription factor, Zif268, known to be implicated in neuronal plasticity and memory formation. We summarize current knowledge about the regulation and function of Zif268 in different types of brain plasticity and memory processes.
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Affiliation(s)
- Alexandra Veyrac
- CNRS, Centre de Neurosciences Paris-Sud, UMR 8195, Orsay, France; Centre de Neurosciences Paris-Sud, Univ Paris-Sud, UMR 8195, Orsay, France
| | - Antoine Besnard
- Harvard Stem Cell Institute, Harvard Medical School, Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Jocelyne Caboche
- INSERM, UMRS 952, Physiopathologie des Maladies du Système Nerveux Central, Paris, France; CNRS, UMR7224, Physiopathologie des Maladies du Système Nerveux Central, Paris, France; UPMC University Paris 6, Paris, France
| | - Sabrina Davis
- CNRS, Centre de Neurosciences Paris-Sud, UMR 8195, Orsay, France; Centre de Neurosciences Paris-Sud, Univ Paris-Sud, UMR 8195, Orsay, France
| | - Serge Laroche
- CNRS, Centre de Neurosciences Paris-Sud, UMR 8195, Orsay, France; Centre de Neurosciences Paris-Sud, Univ Paris-Sud, UMR 8195, Orsay, France
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54
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Callaghan BL, Li S, Richardson R. The elusive engram: what can infantile amnesia tell us about memory? Trends Neurosci 2014; 37:47-53. [DOI: 10.1016/j.tins.2013.10.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 10/24/2013] [Accepted: 10/28/2013] [Indexed: 01/19/2023]
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Pandian GN, Taylor RD, Junetha S, Saha A, Anandhakumar C, Vaijayanthi T, Sugiyama H. Alteration of epigenetic program to recover memory and alleviate neurodegeneration: prospects of multi-target molecules. Biomater Sci 2014; 2:1043-1056. [DOI: 10.1039/c4bm00068d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Next-generation sequence-specific small molecules modulating the epigenetic enzymes (DNMT/HDAC) and signalling factors can precisely turn ‘ON’ the multi-gene network in a neural cell.
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Affiliation(s)
- Ganesh N. Pandian
- Institute for Integrated Cell-Material Sciences (iCeMS)
- Kyoto University
- Kyoto 606-8502, Japan
| | - Rhys D. Taylor
- Department of Chemistry
- Graduate School of Science
- Kyoto University
- Kyoto 606-8501, Japan
| | - Syed Junetha
- Department of Chemistry
- Graduate School of Science
- Kyoto University
- Kyoto 606-8501, Japan
| | - Abhijit Saha
- Department of Chemistry
- Graduate School of Science
- Kyoto University
- Kyoto 606-8501, Japan
| | - Chandran Anandhakumar
- Department of Chemistry
- Graduate School of Science
- Kyoto University
- Kyoto 606-8501, Japan
| | - Thangavel Vaijayanthi
- Department of Chemistry
- Graduate School of Science
- Kyoto University
- Kyoto 606-8501, Japan
| | - Hiroshi Sugiyama
- Institute for Integrated Cell-Material Sciences (iCeMS)
- Kyoto University
- Kyoto 606-8502, Japan
- Department of Chemistry
- Graduate School of Science
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56
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Flavell CR, Lambert EA, Winters BD, Bredy TW. Mechanisms governing the reactivation-dependent destabilization of memories and their role in extinction. Front Behav Neurosci 2013; 7:214. [PMID: 24421762 PMCID: PMC3872723 DOI: 10.3389/fnbeh.2013.00214] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 12/13/2013] [Indexed: 12/28/2022] Open
Abstract
The extinction of learned associations has traditionally been considered to involve new learning, which competes with the original memory for control over behavior. However, a recent resurgence of interest in reactivation-dependent amnesia has revealed that the retrieval of fear-related memory (with what is essentially a brief extinction session) can result in its destabilization. This review discusses some of the cellular and molecular mechanisms that are involved in the destabilization of a memory following its reactivation and/or extinction, and investigates the evidence that extinction may involve both new learning as well as a partial destabilization-induced erasure of the original memory trace.
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Affiliation(s)
- Charlotte R Flavell
- Queensland Brain Institute, The University of Queensland Brisbane, QLD, Australia
| | - Elliot A Lambert
- Queensland Brain Institute, The University of Queensland Brisbane, QLD, Australia
| | - Boyer D Winters
- Department of Psychology, University of Guelph Guelph, ON, Canada
| | - Timothy W Bredy
- Queensland Brain Institute, The University of Queensland Brisbane, QLD, Australia
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Penke Z, Morice E, Veyrac A, Gros A, Chagneau C, LeBlanc P, Samson N, Baumgärtel K, Mansuy IM, Davis S, Laroche S. Zif268/Egr1 gain of function facilitates hippocampal synaptic plasticity and long-term spatial recognition memory. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130159. [PMID: 24298160 DOI: 10.1098/rstb.2013.0159] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
It is well established that Zif268/Egr1, a member of the Egr family of transcription factors, is critical for the consolidation of several forms of memory; however, it is as yet uncertain whether increasing expression of Zif268 in neurons can facilitate memory formation. Here, we used an inducible transgenic mouse model to specifically induce Zif268 overexpression in forebrain neurons and examined the effect on recognition memory and hippocampal synaptic transmission and plasticity. We found that Zif268 overexpression during the establishment of memory for objects did not change the ability to form a long-term memory of objects, but enhanced the capacity to form a long-term memory of the spatial location of objects. This enhancement was paralleled by increased long-term potentiation in the dentate gyrus of the hippocampus and by increased activity-dependent expression of Zif268 and selected Zif268 target genes. These results provide novel evidence that transcriptional mechanisms engaging Zif268 contribute to determining the strength of newly encoded memories.
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Affiliation(s)
- Zsuzsa Penke
- CNRS, Centre de Neurosciences Paris-Sud, UMR 8195, , Orsay 91405, France
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58
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Egr1 regulates lithium-induced transcription of the Period 2 (PER2) gene. Biochim Biophys Acta Mol Basis Dis 2013; 1832:1969-79. [DOI: 10.1016/j.bbadis.2013.06.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Revised: 05/22/2013] [Accepted: 06/19/2013] [Indexed: 11/19/2022]
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Rössger K, Charpin-El-Hamri G, Fussenegger M. Bile acid-controlled transgene expression in mammalian cells and mice. Metab Eng 2013; 21:81-90. [PMID: 24280297 DOI: 10.1016/j.ymben.2013.11.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 10/08/2013] [Accepted: 11/11/2013] [Indexed: 12/27/2022]
Abstract
In recent years, using trigger-inducible mammalian gene switches to design sophisticated transcription-control networks has become standard practice in synthetic biology. These switches provide unprecedented precision, complexity and reliability when programming novel mammalian cell functions. Metabolite-responsive repressors of human-pathogenic bacteria are particularly attractive for use in these orthogonal synthetic mammalian gene switches because the trigger compound sensitivity often matches the human physiological range. We have designed both a bile acid-repressible (BEAROFF) as well as a bile-acid-inducible (BEARON) gene switch by capitalizing on components that have evolved to manage bile acid resistance in Campylobacter jejuni, the leading causative agent of human food-borne enteritis. We have shown that both of these switches enable bile acid-adjustable transgene expression in different mammalian cell lines as well as in mice. For the BEAROFF device, the C. jejuni repressor CmeR was fused to the VP16 transactivation domain to create a synthetic transactivator that activates minimal promoters containing tandem operator modules (Ocme) in a bile acid-repressible manner. Fusion of CmeR to a transsilencing domain resulted in an artificial transsilencer that binds and represses a constitutive Ocme-containing promoter until it is released by addition of bile acid (BEARON). A tailored multi-step tuning program for the inducible gene switch, which included the optimization of individual component performance, control of their relative abundances, the choice of the cell line and trigger compound, resulted in a BEARON device with significantly improved bile acid-responsive control characteristics. Synthetic metabolite-triggered gene switches that are able to interface with host metabolism may foster advances in future gene and cell-based therapies.
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Affiliation(s)
- Katrin Rössger
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, CH-4058 Basel, Switzerland
| | - Ghislaine Charpin-El-Hamri
- Département Génie Biologique, Institut Universitaire de Technologie (IUTA), F-69622 Villeurbanne Cedex, France
| | - Martin Fussenegger
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, CH-4058 Basel, Switzerland; Faculty of Science, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland.
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Recall and reconsolidation of contextual fear memory: differential control by ERK and Zif268 expression dosage. PLoS One 2013; 8:e72006. [PMID: 23977192 PMCID: PMC3745394 DOI: 10.1371/journal.pone.0072006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 07/11/2013] [Indexed: 12/04/2022] Open
Abstract
Compelling evidence points to the existence of independent cellular processes involved in the consolidation and reconsolidation of memory. For instance, a double dissociation has been reported between hippocampal Extracellular-Regulated Kinase-1/2 (ERK1/2) activity being necessary for contextual fear conditioning (CFC) consolidation but not reconsolidation. Conversely, hippocampal expression of the immediate early gene Zif268 is necessary for CFC reconsolidation but not consolidation. Since we previously reported that ERK1/2 controls the transcription of Zif268 in the hippocampus, we examined the precise role of ERK1/2 activity and Zif268 gene expression dosage in CFC memory processing. For this, we first assessed performance of Zif268 homozygous and heterozygous mutant mice in a CFC paradigm. Whereas Zif268−/− mice displayed a deficit of both consolidation and reconsolidation, Zif268+/− mice displayed a selective deficit of reconsolidation only, therefore pointing to the relationship between Zif268 gene expression dosage and CFC memory processing. Zif268 gene expression dosage interfered with the reconsolidation process if and only if CFC memory was relatively recently encoded and directly reactivated. Furthermore, CFC memory strengthening previously reported to involve Zif268 expression in the hippocampus was spared in Zif268+/− mice. Finally, blocking ERK1/2 activity prior to CFC retrieval prevented the deficit of reconsolidation observed in Zif268+/− mice. Collectively, these results highlight a tight relationship between Zif268 gene expression dosage and CFC memory processing. They also suggest that ERK1/2 activity upon CFC memory recall is necessary for its retrieval, a prerequisite for its reactivation and subsequent reconsolidation.
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61
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Molecular signatures and mechanisms of long-lasting memory consolidation and storage. Neurobiol Learn Mem 2013; 106:40-7. [PMID: 23831672 DOI: 10.1016/j.nlm.2013.06.018] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 06/25/2013] [Accepted: 06/26/2013] [Indexed: 12/27/2022]
Abstract
A body of evidence emerged in the last decade regarding late posttraining memory processing. Most of this new information comes from aversively motivated learning tasks that mainly depend on hippocampus, amygdala and insular cortex, and points to the involvement of long-lasting changes in gene expression and protein synthesis in late stages of memory consolidation and storage. Here, we describe recent advances in this field and discuss how recurrent rounds of macromolecular synthesis and its regulation might impact long-term memory storage.
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Miletic G, Lippitt JA, Sullivan KM, Miletic V. Loss of calcineurin in the spinal dorsal horn contributes to neuropathic pain, and intrathecal administration of the phosphatase provides prolonged analgesia. Pain 2013; 154:2024-2033. [PMID: 23778296 DOI: 10.1016/j.pain.2013.06.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 05/21/2013] [Accepted: 06/11/2013] [Indexed: 11/30/2022]
Abstract
Calcineurin (protein phosphatase 3) regulates synaptic plasticity in the brain. The development of neuropathic pain appears dependent on some of the same mechanisms that underlie brain synaptic plasticity. In this study, we examined whether calcineurin regulates chronic constriction injury (CCI)-elicited plasticity in the spinal dorsal horn. CCI animals exhibited mechanical and thermal hypersensitivity 7 days after ligation of the sciatic nerve. Neither control uninjured nor sham-operated animals exhibited pain behavior. Calcineurin activity and content of its Aα isoform were significantly decreased in the ipsilateral postsynaptic density (PSD) of dorsal horn neurons in CCI animals. Calcineurin activity and content in the contralateral PSD of CCI animals or either side of the dorsal horn in sham animals were not modified. The pain behavior in CCI animals was attenuated by intrathecal application of exogenous calcineurin. The treatment was long-lasting as a single injection provided analgesia for 4 days by restoring the phosphatase's activity and Aα content in the PSD. No signs of toxicity were detected up to 14 days after the single intrathecal injection. Intrathecal application of the calcineurin inhibitor FK-506 elicited pain behavior in control uninjured animals and significantly reduced calcineurin activity in the PSD. CCI may elicit neuropathic pain at least in part as a result of the loss of calcineurin-mediated dephosphorylation in the dorsal horn. Addition of the phosphatase by intrathecal injection reverses the injury-elicited loss and provides prolonged pain relief. Clinical therapy with calcineurin may prove to be a novel, effective, and safe approach in the management of well-established neuropathic pain.
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Affiliation(s)
- Gordana Miletic
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
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63
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Slouzkey I, Rosenblum K, Maroun M. Memory of conditioned taste aversion is erased by inhibition of PI3K in the insular cortex. Neuropsychopharmacology 2013; 38:1143-53. [PMID: 23385661 PMCID: PMC3656365 DOI: 10.1038/npp.2013.20] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 11/23/2012] [Accepted: 01/02/2013] [Indexed: 11/08/2022]
Abstract
The conditioned taste aversion (CTA) paradigm, in which association between a novel taste and visceral malaise is formed, gives a unique experimental setting to examine the mechanisms underlying memory acquisition and extinction processes. AKT is a main kinase of the phosphoinositide 3-kinase cascade (PI3K) and has been implicated in long-term memory. We have recently reported that blockade of PI3K in the basolateral amygdala (BLA) before retrieval of fear memory was associated with long-term reduction in fear responses, suggesting a possible role of PI3K inhibition in fear erasure. In this study, we aimed to elucidate whether PI3K has a similar role in the insular cortex (IC), which has a crucial role in CTA acquisition, consolidation, maintenance, and extinction. To that end, we (1) monitored AKT phosphorylation in the IC following CTA acquisition and extinction and (2) inhibited PI3K by local microinjection of the PI3K inhibitor LY294002 at different stages of CTA acquisition and extinction. Our results show that while AKT phosphorylation is increased following CTA learning, it is decreased following CTA extinction. Inhibition of AKT phosphorylation in the IC before or after the first CTA retrieval test resulted in reduction in the aversion index. This reduction in aversion is due to the erasure of the original CTA trace memory, as re-application of the unconditioned stimulus (lithium chloride) did not induce the recovery of aversion in LY294002-treated animals. Our present data add new evidence to suggest that PI3K is engaged in consolidation of aversive memories, as its inhibition is associated with erasure of CTA memory.
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Affiliation(s)
- Ilana Slouzkey
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Kobi Rosenblum
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Mouna Maroun
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
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64
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Sugita M, Yamamoto K, Hirono C, Shiba Y. Functional dissection of sweet and bitter taste pathways. J Oral Biosci 2013. [DOI: 10.1016/j.job.2013.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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65
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Cheng MC, Chuang YA, Lu CL, Chen YJ, Luu SU, Li JM, Hsu SH, Chen CH. Genetic and functional analyses of early growth response (EGR) family genes in schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2012; 39:149-55. [PMID: 22691714 DOI: 10.1016/j.pnpbp.2012.06.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 06/01/2012] [Accepted: 06/02/2012] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Early growth response genes (EGR1, 2, 3, and 4) encode a family of nuclear proteins that function as transcriptional regulators. They are involved in the regulation of synaptic plasticity, learning, and memory, and are implicated in the pathogenesis of schizophrenia. METHODS We conducted a genetic association analysis of 14 SNPs selected from the EGR1, 2, 3, and 4 genes of 564 patients with schizophrenia and 564 control subjects. We also conducted Western blot analysis and promoter activity assay to characterize the EGR genes associated with schizophrenia RESULTS We did not detect a true genetic association of these 14 SNPs with schizophrenia in this sample. However, we observed a nominal over-representation of C/C genotype of rs9990 of EGR2 in female schizophrenia as compared to female control subjects (p=0.012, uncorrected for multiple testing). Further study showed that the average mRNA level of the EGR2 gene in the lymphoblastoid cell lines of female schizophrenia patients was significantly higher than that in female control subjects (p=0.002). We also detected a nominal association of 4 SNPs (rs6747506, rs6718289, rs2229294, and rs3813226) of the EGR4 gene that form strong linkage disequilibrium with schizophrenia in males. Reporter gene assay showed that the haplotype T-A derived from rs6747506 and rs6718289 at the promoter region had significantly reduced promoter activity compared with the haplotype A-G. CONCLUSION Our data suggest a tendency of gender-specific association of EGR2 and EGR4 in schizophrenia, with an elevated expression of EGR2 in lympoblastoid cell lines of female schizophrenia patients and a reduced EGR4 gene expression in male schizophrenia patients.
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Affiliation(s)
- Min-Chih Cheng
- Department of Psychiatry, Yuli Mental Health Research Center, Yuli Veterans Hospital, Hualien, Taiwan
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66
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Baumgärtel K, Mansuy IM. Neural functions of calcineurin in synaptic plasticity and memory. Learn Mem 2012; 19:375-84. [PMID: 22904368 DOI: 10.1101/lm.027201.112] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Major brain functions depend on neuronal processes that favor the plasticity of neuronal circuits while at the same time maintaining their stability. The mechanisms that regulate brain plasticity are complex and engage multiple cascades of molecular components that modulate synaptic efficacy. Protein kinases (PKs) and phosphatases (PPs) are among the most important of these components that act as positive and negative regulators of neuronal signaling and plasticity, respectively. In these cascades, the PP protein phosphatase 2B or calcineurin (CaN) is of particular interest because it is the only Ca(2+)-activated PP in the brain and a major regulator of key proteins essential for synaptic transmission and neuronal excitability. This review describes the primary properties of CaN and illustrates its functions and modes of action by focusing on several representative targets, in particular glutamate receptors, striatal enriched protein phosphatase (STEP), and neuromodulin (GAP43), and their functional significance for synaptic plasticity and memory.
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Affiliation(s)
- Karsten Baumgärtel
- Dorris Neuroscience Center, Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037-1000, USA
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67
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Katche C, Goldin A, Gonzalez C, Bekinschtein P, Medina JH. Maintenance of long-term memory storage is dependent on late posttraining Egr-1 expression. Neurobiol Learn Mem 2012; 98:220-7. [PMID: 22906840 DOI: 10.1016/j.nlm.2012.08.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 07/31/2012] [Accepted: 08/02/2012] [Indexed: 12/20/2022]
Abstract
Expression of immediate-early genes, like Egr-1, has been shown to be induced by activity-dependent synaptic plasticity or behavioral training and is widely thought to play an important role in long-term memory (LTM) formation. However, little is known about the role of Egr-1 in the maintenance of memory storage. Here we show that dorsal hippocampal Egr-1 protein expression is upregulated between 12 and 24 h after strong inhibitory avoidance (IA) training in rats. Local infusion of antisense oligodeoxynucleotide (ASO) to specifically knockdown Egr-1 in the dorsal hippocampus 8 h posttraining impairs LTM tested 7 days, but not 1 day after training, indicating that a delayed learning-associated expression of Egr-1 is necessary for the persistence of LTM storage. In addition, we show that consolidation of the IA memory is accompanied by an increase in Egr-1 protein levels 3 h, but not immediately or 1 h after training. Local infusion of egr-1 ASO 30 min before training in the dorsal hippocampus persistently hinders memory formation measured 1 and 7 days after IA training, indicating the crucial role of Egr-1 in memory formation. Our findings demonstrate that there are at least two waves of Egr-1 expression in the dorsal hippocampus after IA training, an early wave which is involved in IA LTM formation, and a lasting late wave that peaks around 12-24 h after a strong training protocol which is specifically involved in the maintenance of LTM storage.
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Affiliation(s)
- Cynthia Katche
- Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis", Facultad de Medicina, Universidad de Buenos Aires, Argentina
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Leitermann RJ, Sajdyk TJ, Urban JH. Cell-specific expression of calcineurin immunoreactivity within the rat basolateral amygdala complex and colocalization with the neuropeptide Y Y1 receptor. J Chem Neuroanat 2012; 45:50-6. [PMID: 22884996 DOI: 10.1016/j.jchemneu.2012.07.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 07/27/2012] [Accepted: 07/28/2012] [Indexed: 11/17/2022]
Abstract
Neuropeptide Y (NPY) produces potent anxiolytic effects via activation of NPY Y1 receptors (Y1r) within the basolateral amygdaloid complex (BLA). The role of NPY in the BLA was recently expanded to include the ability to produce stress resilience and long-lasting reductions in anxiety-like behavior. These persistent behavioral effects are dependent upon activity of the protein phosphatase, calcineurin (CaN), which has long been associated with shaping long-term synaptic signaling. Furthermore, NPY-induced reductions in anxiety-like behavior persist months after intra-BLA delivery, which together indicate a form of neuronal plasticity had likely occurred. To define a site of action for NPY-induced CaN signaling within the BLA, we employed multi-label immunohistochemistry to determine which cell types express CaN and if CaN colocalizes with the Y1r. We have previously reported that both major neuronal cell populations in the BLA, pyramidal projection neurons and GABAergic interneurons, express the Y1r. Therefore, this current study evaluated CaN immunoreactivity in these cell types, along with Y1r immunoreactivity. Antibodies against calcium-calmodulin kinase II (CaMKII) and GABA were used to identify pyramidal neurons and GABAergic interneurons, respectively. A large population of CaN immunoreactive cells displayed Y1r immunoreactivity (90%). Nearly all (98%) pyramidal neurons displayed CaN immunoreactivity, while only a small percentage of interneurons (10%) contained CaN immunoreactivity. Overall, these anatomical findings provide a model whereby NPY could directly regulate CaN activity in the BLA via activation of the Y1r on CaN-expressing, pyramidal neurons. Importantly, they support BLA pyramidal neurons as prime targets for neuronal plasticity associated with the long-term reductions in anxiety-like behavior produced by NPY injections into the BLA.
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Affiliation(s)
- Randy J Leitermann
- Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA.
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69
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Adaikkan C, Rosenblum K. The role of protein phosphorylation in the gustatory cortex and amygdala during taste learning. Exp Neurobiol 2012; 21:37-51. [PMID: 22792024 PMCID: PMC3381211 DOI: 10.5607/en.2012.21.2.37] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Accepted: 02/17/2012] [Indexed: 01/22/2023] Open
Abstract
Protein phosphorylation and dephosphorylation form a major post-translation mechanism that enables a given cell to respond to ever-changing internal and external environments. Neurons, similarly to any other cells, use protein phosphorylation/dephosphorylation to maintain an internal homeostasis, but they also use it for updating the state of synaptic and intrinsic properties, following activation by neurotransmitters and growth factors. In the present review we focus on the roles of several families of kinases, phosphatases, and other synaptic-plasticity-related proteins, which activate membrane receptors and various intracellular signals to promote transcription, translation and protein degradation, and to regulate the appropriate cellular proteomes required for taste memory acquisition, consolidation and maintenance. Attention is especially focused on the protein phosphorylation state in two forebrain areas that are necessary for taste-memory learning and retrieval: the insular cortex and the amygdala. The various temporal phases of taste learning require the activation of appropriate waves of biochemical signals. These include: extracellular signal regulated kinase I and II (ERKI/II) signal transduction pathways; Ca(2+)-dependent pathways; tyrosine kinase/phosphatase-dependent pathways; brain-derived neurotrophicfactor (BDNF)-dependent pathways; cAMP-responsive element bindingprotein (CREB); and translation-regulation factors, such as initiation and elongation factors, and the mammalian target of rapamycin (mTOR). Interestingly, coding of hedonic and aversive taste information in the forebrain requires activation of different signal transduction pathways.
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70
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Hayes DJ, Northoff G. Common brain activations for painful and non-painful aversive stimuli. BMC Neurosci 2012; 13:60. [PMID: 22676259 PMCID: PMC3464596 DOI: 10.1186/1471-2202-13-60] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 04/18/2012] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Identification of potentially harmful stimuli is necessary for the well-being and self-preservation of all organisms. However, the neural substrates involved in the processing of aversive stimuli are not well understood. For instance, painful and non-painful aversive stimuli are largely thought to activate different neural networks. However, it is presently unclear whether there is a common aversion-related network of brain regions responsible for the basic processing of aversive stimuli. To help clarify this issue, this report used a cross-species translational approach in humans (i.e. meta-analysis) and rodents (i.e. systematic review of functional neuroanatomy). RESULTS Animal and human data combined to show a core aversion-related network, consisting of similar cortical (i.e. MCC, PCC, AI, DMPFC, RTG, SMA, VLOFC; see results section or abbreviation section for full names) and subcortical (i.e. Amyg, BNST, DS, Hab, Hipp/Parahipp, Hyp, NAc, NTS, PAG, PBN, raphe, septal nuclei, Thal, LC, midbrain) regions. In addition, a number of regions appeared to be more involved in pain-related (e.g. sensory cortex) or non-pain-related (e.g. amygdala) aversive processing. CONCLUSIONS This investigation suggests that aversive processing, at the most basic level, relies on similar neural substrates, and that differential responses may be due, in part, to the recruitment of additional structures as well as the spatio-temporal dynamic activity of the network. This network perspective may provide a clearer understanding of why components of this circuit appear dysfunctional in some psychiatric and pain-related disorders.
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Affiliation(s)
- Dave J Hayes
- Mind, Brain Imaging and Neuroethics Research Unit, Institute of Mental Health Research, University of Ottawa, 1145 Carling Avenue, Ottawa, K1Z 7K4, Canada
| | - Georg Northoff
- Mind, Brain Imaging and Neuroethics Research Unit, Institute of Mental Health Research, University of Ottawa, 1145 Carling Avenue, Ottawa, K1Z 7K4, Canada
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71
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Age-dependent rescue by simvastatin of Alzheimer's disease cerebrovascular and memory deficits. J Neurosci 2012; 32:4705-15. [PMID: 22492027 DOI: 10.1523/jneurosci.0169-12.2012] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Alzheimer's disease (AD) is now established as a progressive compromise not only of the neurons but also of the cerebral vasculature. Increasing evidence also indicates that cerebrovascular dysfunction may be a key or an aggravating pathogenic factor in AD, emphasizing the importance to properly control this deficit when aiming for effective therapy. Here, we report that simvastatin (3-6 months, 40 mg/kg/d) completely rescued cerebrovascular reactivity, basal endothelial nitric oxide synthesis, and activity-induced neurometabolic and neurovascular coupling in adult (6 months) and aged (12 months) transgenic mice overexpressing the Swedish and Indiana mutations of the human amyloid precursor protein (AD mice). Remarkably, simvastatin fully restored short- and long-term memory in adult, but not in aged AD mice. These beneficial effects occurred without any decreasing effect of simvastatin on brain amyloid-β (Aβ) levels or plaque load. However, in AD mice with recovered memory, protein levels of the learning- and memory-related immediate early genes c-Fos and Egr-1 were normalized or upregulated in hippocampal CA1 neurons, indicative of restored neuronal function. In contrast, the levels of phospholipase A2, enkephalin, PSD-95, synaptophysin, or glutamate NMDA receptor subunit type 2B were either unaltered in AD mice or unaffected by treatment. These findings disclose new sites of action for statins against Aβ-induced neuronal and cerebrovascular deficits that could be predictive of therapeutic benefit in AD patients. They further indicate that simvastatin and, possibly, other brain penetrant statins bear high therapeutic promise in early AD and in patients with vascular diseases who are at risk of developing AD.
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72
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Abstract
Although the term 'epigenetics' was coined nearly seventy years ago, its critical function in memory processing by the adult CNS has only recently been appreciated. The hypothesis that epigenetic mechanisms regulate memory and behavior was motivated by the need for stable molecular processes that evade turnover of the neuronal proteome. In this article, we discuss evidence that supports a role for neural epigenetic modifications in the formation, consolidation and storage of memory. In addition, we will review the evidence that epigenetic mechanisms regulate synaptic plasticity, a cellular correlate of memory. We will also examine how the concerted action of multiple epigenetic mechanisms with varying spatiotemporal profiles influence selective gene expression in response to behavioral experience. Finally, we will suggest key areas for future research that will help elucidate the complex, vital and still mysterious, role of epigenetic mechanisms in neural function and behavior.
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Affiliation(s)
- Faraz A Sultan
- Department of Neurobiology, University of Alabama at Birmingham, Evelyn F McKnight Brain Institute, 1007 Shelby Building, 1825 University Boulevard Birmingham, AL 35294-2182, USA
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73
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Yang Y, Shu X, Liu D, Shang Y, Wu Y, Pei L, Xu X, Tian Q, Zhang J, Qian K, Wang YX, Petralia RS, Tu W, Zhu LQ, Wang JZ, Lu Y. EPAC null mutation impairs learning and social interactions via aberrant regulation of miR-124 and Zif268 translation. Neuron 2012; 73:774-88. [PMID: 22365550 DOI: 10.1016/j.neuron.2012.02.003] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2011] [Indexed: 10/28/2022]
Abstract
EPAC proteins are the guanine nucleotide exchange factors that act as the intracellular receptors for cyclic AMP. Two variants of EPAC genes including EPAC1 and EPAC2 are cloned and are widely expressed throughout the brain. But, their functions in the brain remain unknown. Here, we genetically delete EPAC1 (EPAC1(-/-)), EPAC2 (EPAC2(-/-)), or both EPAC1 and EPAC2 genes (EPAC(-/-)) in the forebrain of mice. We show that EPAC null mutation impairs long-term potentiation (LTP) and that this impairment is paralleled with the severe deficits in spatial learning and social interactions and is mediated in a direct manner by miR-124 transcription and Zif268 translation. Knockdown of miR-124 restores Zif268 and hence reverses all aspects of the EPAC(-/-) phenotypes, whereas expression of miR-124 or knockdown of Zif268 reproduces the effects of EPAC null mutation. Thus, EPAC proteins control miR-124 transcription in the brain for processing spatial learning and social interactions.
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Affiliation(s)
- Ying Yang
- Key Laboratory of Neurological Disease, Ministry of Education, China, and Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
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74
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Kim SH, Song JY, Joo EJ, Lee KY, Shin SY, Lee YH, Ahn YM, Kim YS. Genetic association of the EGR2 gene with bipolar disorder in Korea. Exp Mol Med 2012; 44:121-9. [PMID: 22089088 PMCID: PMC3296808 DOI: 10.3858/emm.2012.44.2.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2011] [Indexed: 12/23/2022] Open
Abstract
The early growth response gene 2 (EGR2) is located at chromosome 10q21, one of the susceptibility loci in bipolar disorder (BD). EGR2 is involved in cognitive function, myelination, and signal transduction related to neuregulin-ErbB receptor, Bcl-2 family proteins, and brain-derived neurotrophic factor. This study investigated the genetic association of the EGR2 gene with BD and schizophrenia (SPR) in Korea. In 946 subjects (350 healthy controls, 352 patients with BD, and 244 with SPR), nine single nucleotide polymorphisms (SNPs) in the EGR2 gene region were genotyped. Five SNPs showed nominally significant allelic associations with BD (rs2295814, rs61865882, rs10995315, rs2297488, and rs2297489), and the positive associations of all except rs2297488 remained significant after multiple testing correction. Linkage disequilibrium structure analysis revealed two haplotype blocks. Among the common identified haplotypes (frequency > 5%), 'T-G-A-C-T (block 1)' and 'A-A-G-C (block 2)' haplotypes were over-represented, while 'C-G-G-T-T (block 1)' haplotype was under-represented in BD. In contrast, no significant associations were found with SPR. Although an extended analysis with a larger sample size or independent replication is required, these findings suggest a genetic association of EGR2 with BD. Combined with a plausible biological function of EGR2, the EGR2 gene is a possible susceptibility gene in BD.
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Affiliation(s)
- Se Hyun Kim
- Department of Neuropsychiatry, Seoul National University Hospital, Korea
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75
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Millan MJ, Agid Y, Brüne M, Bullmore ET, Carter CS, Clayton NS, Connor R, Davis S, Deakin B, DeRubeis RJ, Dubois B, Geyer MA, Goodwin GM, Gorwood P, Jay TM, Joëls M, Mansuy IM, Meyer-Lindenberg A, Murphy D, Rolls E, Saletu B, Spedding M, Sweeney J, Whittington M, Young LJ. Cognitive dysfunction in psychiatric disorders: characteristics, causes and the quest for improved therapy. Nat Rev Drug Discov 2012; 11:141-68. [PMID: 22293568 DOI: 10.1038/nrd3628] [Citation(s) in RCA: 786] [Impact Index Per Article: 65.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Studies of psychiatric disorders have traditionally focused on emotional symptoms such as depression, anxiety and hallucinations. However, poorly controlled cognitive deficits are equally prominent and severely compromise quality of life, including social and professional integration. Consequently, intensive efforts are being made to characterize the cellular and cerebral circuits underpinning cognitive function, define the nature and causes of cognitive impairment in psychiatric disorders and identify more effective treatments. Successful development will depend on rigorous validation in animal models as well as in patients, including measures of real-world cognitive functioning. This article critically discusses these issues, highlighting the challenges and opportunities for improving cognition in individuals suffering from psychiatric disorders.
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Affiliation(s)
- Mark J Millan
- Institut de Recherche Servier, 78290 Croissy/Seine, France.
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76
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Role of calcineurin in inhibiting disadvantageous associations. Neuroscience 2012; 203:144-52. [PMID: 22230044 DOI: 10.1016/j.neuroscience.2011.12.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 12/06/2011] [Accepted: 12/08/2011] [Indexed: 11/20/2022]
Abstract
Calcineurin is an important calcium-dependent phosphatase that is evolutionarily conserved in all studied species, and has been implicated in the consolidation and maintenance of new memories. However, recent evidence has extended the role of calcineurin. In contrast to learning tasks that require behavioral acquisition, extinction tasks that require behavioral inhibition have been shown to be reliant on calcineurin. In the present study, using a Morris water maze, we have demonstrated that pharmacological inhibition of calcineurin causes augmentation of spatial learning and perseveration of spatial reversal-learning in a dose-dependent manner. Direct infusions of a specific calcineurin inhibitor, cyclosporine A, into the dorsal hippocampi bilaterally, prior to spatial learning, led to increased learning, whereas similar injections of cyclosporine A following a spatial learning task and prior to a spatial reversal-learning task resulted in perseveration of reversal-learning. Our results indicate that injections of cyclosporin A resulted in decreased calcineurin activity in the dorsal hippocampus and increased difficulty in switching to new task demands, in a dose-dependent manner, despite evidence indicating no deficit in ability to learn new information. Therefore, calcineurin activity contributes to the inhibition of previously learned but unwanted behavioral responses during competitive spatial learning. Involvement of calcineurin in extinction of fear memory has recently been demonstrated. Our results also indicate that calcineurin activity plays a role in memory extinction in spatial memory tasks, and therefore, suggest that calcineurin might be an important molecule in mediating behavioral flexibility in general.
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77
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Gitzinger M, Kemmer C, Fluri DA, El-Baba MD, Weber W, Fussenegger M. The food additive vanillic acid controls transgene expression in mammalian cells and mice. Nucleic Acids Res 2011; 40:e37. [PMID: 22187155 PMCID: PMC3300003 DOI: 10.1093/nar/gkr1251] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Trigger-inducible transcription-control devices that reversibly fine-tune transgene expression in response to molecular cues have significantly advanced the rational reprogramming of mammalian cells. When designed for use in future gene- and cell-based therapies the trigger molecules have to be carefully chosen in order to provide maximum specificity, minimal side-effects and optimal pharmacokinetics in a mammalian organism. Capitalizing on control components that enable Caulobacter crescentus to metabolize vanillic acid originating from lignin degradation that occurs in its oligotrophic freshwater habitat, we have designed synthetic devices that specifically adjust transgene expression in mammalian cells when exposed to vanillic acid. Even in mice transgene expression was robust, precise and tunable in response to vanillic acid. As a licensed food additive that is regularly consumed by humans via flavoured convenience food and specific fresh vegetable and fruits, vanillic acid can be considered as a safe trigger molecule that could be used for diet-controlled transgene expression in future gene- and cell-based therapies.
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Affiliation(s)
- Marc Gitzinger
- Department of Biosystems Science and Engineering (D-BSSE), ETH Zurich, Mattenstrasse 26, CH-4058 Basel, Switzerland
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78
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Abstract
Sleep is a fundamental biological process for all animals. However, the molecular mechanisms that regulate sleep are still poorly understood. Here we report that sleep-like behavior in Drosophila is severely impaired by mutations in sarah (sra), a member of the Regulator of Calcineurin (RCAN) family of genes. Sleep reduction in sra mutants is highly correlated with decreases in Sra protein levels. Pan-neural expression of sra rescues this behavioral phenotype, indicating that neuronal sra function is required for normal sleep. Since Sra regulates calcineurin (CN), we generated and examined the behavior of knock-out mutants for all Drosophila CN genes: CanA-14F, Pp2B-14D, and CanA1 (catalytic subunits), and CanB and CanB2 (regulatory subunits). While all mutants show at least minor changes in sleep, CanA-14F(KO) and CanB(KO) have striking reductions, suggesting that these are the major CN subunits regulating sleep. In addition, neuronal expression of constitutively active forms of CN catalytic subunits also significantly reduces sleep, demonstrating that both increases and decreases in CN activity inhibit sleep. sra sleep defects are suppressed by CN mutations, indicating that sra and CN affect sleep through a common mechanism. Our results demonstrate that CN and its regulation by Sra are required for normal sleep in Drosophila and identify a critical role of Ca(2+)/calmodulin-dependent signaling in sleep regulation.
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79
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Hayes DJ, Northoff G. Identifying a network of brain regions involved in aversion-related processing: a cross-species translational investigation. Front Integr Neurosci 2011; 5:49. [PMID: 22102836 PMCID: PMC3215229 DOI: 10.3389/fnint.2011.00049] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 08/19/2011] [Indexed: 12/26/2022] Open
Abstract
The ability to detect and respond appropriately to aversive stimuli is essential for all organisms, from fruit flies to humans. This suggests the existence of a core neural network which mediates aversion-related processing. Human imaging studies on aversion have highlighted the involvement of various cortical regions, such as the prefrontal cortex, while animal studies have focused largely on subcortical regions like the periaqueductal gray and hypothalamus. However, whether and how these regions form a core neural network of aversion remains unclear. To help determine this, a translational cross-species investigation in humans (i.e., meta-analysis) and other animals (i.e., systematic review of functional neuroanatomy) was performed. Our results highlighted the recruitment of the anterior cingulate cortex, the anterior insula, and the amygdala as well as other subcortical (e.g., thalamus, midbrain) and cortical (e.g., orbitofrontal) regions in both animals and humans. Importantly, involvement of these regions remained independent of sensory modality. This study provides evidence for a core neural network mediating aversion in both animals and humans. This not only contributes to our understanding of the trans-species neural correlates of aversion but may also carry important implications for psychiatric disorders where abnormal aversive behavior can often be observed.
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Affiliation(s)
- Dave J Hayes
- Mind, Brain Imaging and Neuroethics Research Unit, Institute of Mental Health Research, University of Ottawa Ottawa, ON, Canada
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80
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Lin Q, Wei W, Coelho CM, Li X, Baker-Andresen D, Dudley K, Ratnu VS, Boskovic Z, Kobor MS, Sun YE, Bredy TW. The brain-specific microRNA miR-128b regulates the formation of fear-extinction memory. Nat Neurosci 2011; 14:1115-7. [PMID: 21841775 DOI: 10.1038/nn.2891] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 07/05/2011] [Indexed: 12/14/2022]
Abstract
MicroRNAs are small non-coding RNAs that mediate post-transcriptional gene silencing. Fear-extinction learning in C57/Bl6J mice led to increased expression of the brain-specific microRNA miR-128b, which disrupted stability of several plasticity-related target genes and regulated formation of fear-extinction memory. Increased miR-128b activity may therefore facilitate the transition from retrieval of the original fear memory toward the formation of a new fear-extinction memory.
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Affiliation(s)
- Quan Lin
- Intellectual Development and Disabilities Research Center, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, USA
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81
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Reconsolidation or extinction: transcription factor switch in the determination of memory course after retrieval. J Neurosci 2011; 31:5562-73. [PMID: 21490196 DOI: 10.1523/jneurosci.6066-10.2011] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In fear conditioning, aversive stimuli are readily associated with contextual features. A brief reexposure to the training context causes fear memory reconsolidation, whereas a prolonged reexposure induces memory extinction. The regulation of hippocampal gene expression plays a key role in contextual memory consolidation and reconsolidation. However, the mechanisms that determine whether memory will reconsolidate or extinguish are not known. Here, we demonstrate opposing roles for two evolutionarily related transcription factors in the mouse hippocampus. We found that nuclear factor-κB (NF-κB) is required for fear memory reconsolidation. Conversely, calcineurin phosphatase inhibited NF-κB and induced nuclear factor of activated T-cells (NFAT) nuclear translocation in the transition between reconsolidation and extinction. Accordingly, the hippocampal inhibition of both calcineurin and NFAT independently impaired memory extinction, whereas inhibition of NF-κB enhanced memory extinction. These findings represent the first insight into the molecular mechanisms that determine memory reprocessing after retrieval, supporting a transcriptional switch that directs memory toward reconsolidation or extinction. The precise molecular characterization of postretrieval processes has potential importance to the development of therapeutic strategies for fear memory disorders.
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82
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Park HG, Kim SH, Kim HS, Ahn YM, Kang UG, Kim YS. Repeated electroconvulsive seizure treatment in rats reduces inducibility of early growth response genes and hyperactivity in response to cocaine administration. Prog Neuropsychopharmacol Biol Psychiatry 2011; 35:1014-21. [PMID: 21334415 DOI: 10.1016/j.pnpbp.2011.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 01/28/2011] [Accepted: 02/11/2011] [Indexed: 12/27/2022]
Abstract
Regulated expression of immediate early genes (IEGs) in the brain reflects neuronal activity in response to various stimuli and recruits specific gene programs involved in long-term neuronal modification and behavioral alterations. Repeated electroconvulsive seizure (ECS) treatment reduces the expression level of several IEGs, such as c-fos, which play important roles in psychostimulant-induced behavioral changes. In this study, we investigated the effects of repeated ECS treatment on the basal expression level of IEGs and its effects on cocaine-induced activation of IEGs and locomotor activity in rats. Repeated ECS treatment for 10days (E10×) reduced Egr1, Egr2, Egr3, and c-fos mRNA and protein levels in the rat frontal cortex at 24h after the last ECS treatment, and these changes were evident in the neuronal cells of the prefrontal cortex. In particular, downregulation of Egr1 and c-fos was evident until 5days after the last ECS treatment. Moreover, E10× pretreatment attenuated the cocaine-induced increase in Egr1, Egr2, and c-fos expression in the rat frontal cortex, whereas phosphorylation of ERK1/2, one of the representative upstream activators of these genes, increased significantly following cocaine treatment. Additionally, E10× pretreatment attenuated the increase in locomotor activity in response to a cocaine injection. In conclusion, repeated ECS treatment reduced the expression and inducibility of Egrs and c-fos, which could attenuate the response of the brain to psychostimulants.
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Affiliation(s)
- Hong Geun Park
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
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83
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Changes in calcineurin message, enzyme activity and protein content in the spinal dorsal horn are associated with chronic constriction injury of the rat sciatic nerve. Neuroscience 2011; 188:142-7. [PMID: 21596102 DOI: 10.1016/j.neuroscience.2011.05.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 04/15/2011] [Accepted: 05/03/2011] [Indexed: 11/23/2022]
Abstract
Plasticity in the spinal dorsal horn is thought to underlie the development of neuropathic pain. Calcineurin (protein phosphatase 3) plays an important role in plasticity in the brain. Here we examined whether chronic constriction injury (CCI) of the sciatic nerve modifies calcineurin expression in the spinal dorsal horn. Male rats were assigned to control (uninjured), sham-operated or CCI groups. CCI animals exhibited both a shift in weight bearing and a reduction in paw withdrawal latencies as signs of pain behavior. At 3 days (3D) the pain behavior was associated with a significant increase in calcineurin gene expression, enzyme activity and content of its Aα isoform in the ipsilateral spinal dorsal horn. In contrast, while the pain behavior persisted at 7 days (7D) calcineurin gene expression returned to control levels and activity and protein content decreased. A single intrathecal injection of MK-801 15 min before the ligation attenuated both signs of pain behavior in 3D but not 7D CCI animals. The same pre-treatment also prevented the CCI-associated increases in calcineurin in these animals. These data suggested an involvement of calcineurin in CCI-elicited neuropathic pain. The time-dependent divergent changes in calcineurin expression may underlie the different phases of neuropathic pain development.
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84
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Cheval H, Chagneau C, Levasseur G, Veyrac A, Faucon-Biguet N, Laroche S, Davis S. Distinctive features of Egr transcription factor regulation and DNA binding activity in CA1 of the hippocampus in synaptic plasticity and consolidation and reconsolidation of fear memory. Hippocampus 2011; 22:631-42. [PMID: 21425206 DOI: 10.1002/hipo.20926] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2010] [Indexed: 01/17/2023]
Abstract
Activity-dependent regulation of Egr1/Zif268, a transcription factor (TF) of the Egr family, is essential for stabilization of dentate gyrus synaptic plasticity and consolidation and reconsolidation of several forms of memory. The gene can be rapidly induced in selective brain circuits after certain types of learning or after recall. Here, we focused on area CA1 and examined regulation of Egr1, Egr2, and Egr3 mRNA and protein, and their DNA binding activity to the Egr response element (ERE) at different times after LTP in vivo and after learning and recall of a fear memory. We found LTP in CA1 leads to rapid induction of the three Egrs, however only Egr1 protein was overexpressed without a co-ordinated change in binding activity, indicating a fundamental difference between CA1 and dentate gyrus LTP. Our investigations in fear memory reveal that both learning and retrieval lead to an increase in binding of constitutively expressed Egr1 and Egr3 to the ERE, but not Egr2. Memory recall was also associated with increased Egr1 protein translation. The nature and temporal dynamics of these changes and tests for interactions between TFs suggest that in addition to ERE-mediated transcription, Egr1 in CA1 may interact with the TF c-Fos to regulate genes via other DNA response elements.
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Affiliation(s)
- Hélène Cheval
- CNRS, Centre de Neurosciences Paris-Sud, UMR 8195, Orsay, F-91405, France.
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85
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Epp J, Scott N, Galea L. Strain differences in neurogenesis and activation of new neurons in the dentate gyrus in response to spatial learning. Neuroscience 2011; 172:342-54. [DOI: 10.1016/j.neuroscience.2010.10.025] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 10/09/2010] [Accepted: 10/11/2010] [Indexed: 10/18/2022]
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86
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Esdin J, Pearce K, Glanzman DL. Long-term habituation of the gill-withdrawal reflex in aplysia requires gene transcription, calcineurin and L-type voltage-gated calcium channels. Front Behav Neurosci 2010; 4:181. [PMID: 21152260 PMCID: PMC2998902 DOI: 10.3389/fnbeh.2010.00181] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 11/12/2010] [Indexed: 11/30/2022] Open
Abstract
Although habituation is possibly the simplest form of learning, we still do not fully understand the neurobiological basis of habituation in any organism. To advance the goal of a comprehensive understanding of habituation, we have studied long-term habituation (LTH) of the gill-withdrawal reflex (GWR) in the marine snail Aplysia californica. Previously, we showed that habituation of the GWR in a reduced preparation lasts for up to 12 h, and depends on protein synthesis, as well as activation of protein phosphatases 1 and 2A and postsynaptic glutamate receptors. Here, we have used the reduced preparation to further analyze the mechanisms of LTH in Aplysia. We found that LTH of the GWR depends on RNA synthesis because it was blocked by both the irreversible transcriptional inhibitor actinomycin-D and the reversible transcriptional inhibitor, 5,6-dichlorobenzimidazole riboside (DRB). In addition, LTH requires activation of protein phosphatase 2B (calcineurin), because it was disrupted by ascomycin. Finally, LTH was blocked by nitrendipine, which indicates that activation of l-type voltage-gated Ca2+ channels is required for this form of learning. Together with our previous results, the present results indicate that exclusively presynaptic mechanisms, although possibly sufficient for short-term habituation, are insufficient for LTH. Rather, LTH must involve postsynaptic, as well as presynaptic, mechanisms.
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Affiliation(s)
- Joseph Esdin
- Department of Integrative Biology and Physiology, University of California Los Angeles, CA, USA
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87
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Abstract
We have previously reported that the reconsolidation and extinction of hippocampal-dependent contextual fear memory can be initiated by a single context conditioned stimulus (CS) presentation of either short or long duration, and that both processes require protein synthesis in this brain region. Furthermore, reconsolidation depends on Zif268 activity in this region. Here we show that by infusing a recombinant brain-derived neurotrophic factor (rBDNF) directly into the brain of rats, that high levels of mature BDNF in the hippocampus at retrieval constrain the extinction of the fear memory after prolonged memory recall. We also show after a short CS exposure that reconsolidation was impaired using antisense oligonucleotides targeting Zif268, and that, similarly, reductions in conditioned behavior were observed after prolonged CS presentation when extinction is constrained by high levels of BDNF. This is direct evidence that in the mammalian brain extinction proceeds exclusively after prolonged CS exposure. In addition, that BDNF activity in the hippocampus contributes to a molecular switch for the extinction of hippocampal-dependent memory.
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Affiliation(s)
- Anne Kirtley
- Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AX, United Kingdom
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88
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Spires-Jones TL, Kay K, Matsouka R, Rozkalne A, Betensky RA, Hyman BT. Calcineurin inhibition with systemic FK506 treatment increases dendritic branching and dendritic spine density in healthy adult mouse brain. Neurosci Lett 2010; 487:260-3. [PMID: 20970476 DOI: 10.1016/j.neulet.2010.10.033] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 10/02/2010] [Accepted: 10/13/2010] [Indexed: 10/18/2022]
Abstract
Calcineurin has been implicated as part of a critical signaling pathway for learning and memory, and recent data suggest that calcineurin activation mediates some of the neurotoxicity of the Alzheimer related neurotoxin Aβ. Immunosuppression via calcineurin inhibition with the compound FK506 is an important treatment for organ transplant patients. Here we use Golgi impregnation techniques, along with a new survival analysis-based statistical approach for analysis of dendritic complexity, to show that in healthy adult mice one week of treatment with FK506 affects both the branching patterns and dendritic spine density of cortical neurons. These results indicate that calcineurin inhibition leads to readily detectable changes in brain morphology, further implicating calcineurin related pathways in both the function and structure of the adult brain.
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Affiliation(s)
- Tara L Spires-Jones
- Massachusetts General Hospital/Harvard Medical School, MassGeneral Institute for Neurodegenerative Diseases, 114 16th Street, Charlestown, MA 02129, USA
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89
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Takayama Y, Sahu D, Iwahara J. NMR studies of translocation of the Zif268 protein between its target DNA Sites. Biochemistry 2010; 49:7998-8005. [PMID: 20718505 DOI: 10.1021/bi100962h] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Zif268 is a zinc-finger protein containing three Cys(2)-His(2)-type zinc-finger domains that bind the target DNA sequence GCGTGGGCG in a cooperative manner. In this work, we characterized translocation of the Zif268 protein between its target DNA sites using NMR spectroscopy. The residual dipolar coupling data and NMR chemical shift data suggested that the structure of the sequence-specific complex between Zif268 and its target DNA in solution is the same as the crystal structure. Using two-dimensional heteronuclear (1)H-(15)N correlation spectra recorded with the fast acquisition method, we analyzed the kinetics of the process in which the Zif268 protein transfers from a target site to another on a different DNA molecule on a minute to hour time scale. By globally fitting the time-course data collected at some different DNA concentrations, we determined the dissociation rate constant for the specific complex and the second-order rate constant for direct transfer of Zif268 from one target site to another. Interestingly, direct transfer of the Zif268 protein between its target sites is >30000-fold slower than corresponding direct transfers of the HoxD9 and the Oct-1 proteins, although the affinities of the three proteins to their target DNA sites are comparable. We also analyzed translocation of the Zif268 protein between two target sites on the same DNA molecules. The populations of the proteins bound to the target sites were found to depend on locations and orientations of the target sites.
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Affiliation(s)
- Yuki Takayama
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555-1068, USA
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90
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Tweedie-Cullen RY, Mansuy IM. Towards a better understanding of nuclear processes based on proteomics. Amino Acids 2010; 39:1117-30. [PMID: 20730591 DOI: 10.1007/s00726-010-0723-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Accepted: 08/09/2010] [Indexed: 12/25/2022]
Abstract
The complex structural and functional organisation of the brain warrants the application of high-throughput approaches to study its functional alterations in physiological and pathological conditions. Such approaches have greatly benefited from advances in proteomics and genomics, and from their combination with computational modelling. They have been particularly instrumental for the analysis of processes such as the post-translational modification (PTM) of proteins, a critical biological process in the nervous system that remains not well studied. Protein PTMs are dynamic covalent marks that can be induced by activity and allow the maintenance of a trace of this activity. In the nucleus, they can modulate histone proteins and the components of the transcriptional machinery, and thereby contribute to regulating gene expression. PTMs do however need to be tightly controlled for proper chromatin functions. This review provides a synopsis of methods available to study PTMs and protein expression based on high-throughput mass spectrometry (MS), and covers basic concepts of traditional 'shot-gun'-based MS. It describes classical and emerging proteomic approaches such as multiple reaction monitoring and electron transfer dissociation, and their application to the analyses of nuclear processes in the brain.
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Affiliation(s)
- Ry Y Tweedie-Cullen
- Department of Biology of the ETH Zurich and Medical Faculty of the University Zurich, 8057, Zurich, Switzerland.
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91
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Garcia-delaTorre P, Rodríguez-Ortiz CJ, Balderas I, Bermúdez-Rattoni F. Differential participation of temporal structures in the consolidation and reconsolidation of taste aversion extinction. Eur J Neurosci 2010; 32:1018-23. [DOI: 10.1111/j.1460-9568.2010.07365.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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92
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Oberbeck DL, McCormack S, Houpt TA. Intra-amygdalar okadaic acid enhances conditioned taste aversion learning and CREB phosphorylation in rats. Brain Res 2010; 1348:84-94. [PMID: 20599840 DOI: 10.1016/j.brainres.2010.06.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 06/09/2010] [Accepted: 06/10/2010] [Indexed: 11/26/2022]
Abstract
Protein phosphatases (PPs) regulate many substrates implicated in learning and memory. Conditioned taste aversion (CTA) learning, in which animals associate a novel taste paired with a toxin and subsequently avoid the taste, is dependent on several serine/threonine phosphatase substrates and the PP1-binding protein spinophilin. In order to examine the effects of PP1/2A blockade on CTA acquisition and extinction, rats received bilateral infusions of okadaic acid (OA) (100nM, 1microl/hemisphere) or vehicle (0.15M NaCl) into the amygdala either 5min prior to, or 5min after, a single pairing of sodium saccharin (0.125%, 10-min access) and LiCl or NaCl (0.15M, 3ml/kg i.p.). Two-bottle, 24-h preference tests were conducted for 13days to measure CTA expression and extinction. Rats conditioned with saccharin and LiCl showed a decreased preference for saccharin, and OA administered before (but not after) the pairing of saccharin and LiCl resulted in a significantly stronger CTA that did not extinguish over 13days. The enhancement of the CTA was not due to aversive effects of OA, because rats given OA and a pairing of saccharin and NaCl did not acquire a CTA. Finally, OA administration increased levels of phosphorylated CREB immunoreactivity following a CTA trial. Together, these results suggest a critical role for PP1/2A during normal CTA learning. Because CTA learning was enhanced only when OA was given prior to conditioning, phosphatase activity may be a constraint on learning during the taste-toxin interval but not during acquisition and consolidation processes that occur after toxin administration.
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Affiliation(s)
- Denesa L Oberbeck
- Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, FL 32306, USA
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93
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Persistence of long-term memory storage: new insights into its molecular signatures in the hippocampus and related structures. Neurotox Res 2010; 18:377-85. [PMID: 20151243 DOI: 10.1007/s12640-010-9155-5] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 01/19/2010] [Accepted: 01/19/2010] [Indexed: 12/21/2022]
Abstract
Although much is known about long-term memory (LTM) consolidation, what puts the "long" in LTM is the exclusive feature of persisting over time. However, until recently the molecular mechanisms underneath memory persistence had never been properly studied. In rats, the protein translation inhibitor anisomycin impaired memory persistence when injected into the dorsal hippocampus 12 h after inhibitory avoidance (IA) training without affecting memory formation. Here, we also show learning-induced changes in hippocampal c-Fos, Homer 1a, Akt, CamKIIα, and ERK2 levels around 18-24 h after IA training. Thus, memory persistence is associated with a late phase of plasticity-related protein synthesis in the hippocampus.
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94
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Mitochondrial DNA toxicity in forebrain neurons causes apoptosis, neurodegeneration, and impaired behavior. Mol Cell Biol 2010; 30:1357-67. [PMID: 20065039 DOI: 10.1128/mcb.01149-09] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Mitochondrial dysfunction underlying changes in neurodegenerative diseases is often associated with apoptosis and a progressive loss of neurons, and damage to the mitochondrial genome is proposed to be involved in such pathologies. In the present study we designed a mouse model that allows us to specifically induce mitochondrial DNA toxicity in the forebrain neurons of adult mice. This is achieved by CaMKIIalpha-regulated inducible expression of a mutated version of the mitochondrial UNG DNA repair enzyme (mutUNG1). This enzyme is capable of removing thymine from the mitochondrial genome. We demonstrate that a continual generation of apyrimidinic sites causes apoptosis and neuronal death. These defects are associated with behavioral alterations characterized by increased locomotor activity, impaired cognitive abilities, and lack of anxietylike responses. In summary, whereas mitochondrial base substitution and deletions previously have been shown to correlate with premature and natural aging, respectively, we show that a high level of apyrimidinic sites lead to mitochondrial DNA cytotoxicity, which causes apoptosis, followed by neurodegeneration.
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95
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Baumgärtel K, Tweedie-Cullen RY, Grossmann J, Gehrig P, Livingstone-Zatchej M, Mansuy IM. Changes in the proteome after neuronal zif268 overexpression. J Proteome Res 2009; 8:3298-316. [PMID: 19374395 DOI: 10.1021/pr801000r] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Long-lasting forms of brain plasticity are a cellular basis for long-term memory, and their disturbance underlies pathological conditions such as dementia and cognitive impairment. Neuronal plasticity is a complex process that utilizes molecular cascades in the cytoplasm and the nucleus and involves numerous transcription factors, in particular, immediate early genes (IEGs). The signaling cascades that control IEGs are fairly well described, but the downstream transcriptional response is poorly understood, especially its late components. Here, we investigated the response induced by the IEG Zif268 in the adult brain in relation to long-term memory. Using a mouse model with increased neuronal expression of Zif268 that leads to improved memory, we identified an ensemble of proteins regulated by Zif268 expression and differentiated between direct and indirect targets based on the presence of a consensus binding motif in their promoter. We show that Zif268 regulates numerous substrates with diverse biological functions including protein modification and degradation (proteasome-core complex), phosphorylation, cell division, sensory perception, metabolism, and metal ion transport. The results provide a comprehensive and quantitative data set characterizing the Zif268-dependent proteome in the adult mouse brain and offers biologically important new insight into activity-dependent pathways downstream of IEGs.
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Affiliation(s)
- Karsten Baumgärtel
- Brain Research Institute, Medical Faculty of the University of Zurich, Switzerland
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96
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Dardou D, Datiche F, Cattarelli M. Does the olfactory cue activate the same brain network during aging in the rat after taste potentiated odor aversion retrieval? Neurobiol Learn Mem 2009; 93:137-50. [PMID: 19761859 DOI: 10.1016/j.nlm.2009.09.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 09/03/2009] [Accepted: 09/09/2009] [Indexed: 11/29/2022]
Abstract
Depending on the brain networks involved, aging is not accompanied by a general decrease in learning and memory capabilities. We demonstrated previously that learning and retrieval of taste potentiated odor aversion (TPOA) is preserved, and even slightly improved, in senescent rats showing some memory deficiencies in cognitive tasks (Dardou, Datiche, & Cattarelli, 2008). TPOA is a particular behavior in which the simultaneous presentation of odor and taste cues followed by a delayed visceral illness leads to a robust aversion towards both conditioned stimuli, which permits diet selection and animal survival. The present experiment was performed in order to investigate the stability or the evolution of the brain network underlying TPOA retrieval during aging. By using immunocytochemical detection of Fos and Egr1 proteins we mapped the cerebral activation induced by TPOA retrieval elicited by the odor presentation in the young, the adult and the senescent rats. The pattern of brain activation changed and the number of activated areas decreased with age. Nevertheless, the piriform cortex and the basolateral amygdala nucleus were always activated and seemed essential for TPOA retrieval. The hippocampus and the neocortical areas could have different implications in TPOA memory in relation to age. The patterns of expression of Fos and Egr1 were different, suggesting their differential involvement in TPOA retrieval. Data are discussed according to the possible roles of the brain areas studied and a model of schematic brain network subtending TPOA retrieval induced by the odor cue is proposed.
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Affiliation(s)
- David Dardou
- Centre Européen des Sciences du Goût, CNRS UMR 5170, 15 rue Hugues Picardet, 21000 Dijon, France.
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97
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Controlling transgene expression in subcutaneous implants using a skin lotion containing the apple metabolite phloretin. Proc Natl Acad Sci U S A 2009; 106:10638-43. [PMID: 19549857 DOI: 10.1073/pnas.0901501106] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Adjustable control of therapeutic transgenes in engineered cell implants after transdermal and topical delivery of nontoxic trigger molecules would increase convenience, patient compliance, and elimination of hepatic first-pass effect in future therapies. Pseudomonas putida DOT-T1E has evolved the flavonoid-triggered TtgR operon, which controls expression of a multisubstrate-specific efflux pump (TtgABC) to resist plant-derived defense metabolites in its rhizosphere habitat. Taking advantage of the TtgR operon, we have engineered a hybrid P. putida-mammalian genetic unit responsive to phloretin. This flavonoid is contained in apples, and, as such, or as dietary supplement, regularly consumed by humans. The engineered mammalian phloretin-adjustable control element (PEACE) enabled adjustable and reversible transgene expression in different mammalian cell lines and primary cells. Due to the short half-life of phloretin in culture, PEACE could also be used to program expression of difficult-to-produce protein therapeutics during standard bioreactor operation. When formulated in skin lotions and applied to the skin of mice harboring transgenic cell implants, phloretin was able to fine-tune target genes and adjust heterologous protein levels in the bloodstream of treated mice. PEACE-controlled target gene expression could foster advances in biopharmaceutical manufacturing as well as gene- and cell-based therapies.
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98
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Lam BYH, Zhang W, Enticknap N, Haggis E, Cader MZ, Chawla S. Inverse regulation of plasticity-related immediate early genes by calcineurin in hippocampal neurons. J Biol Chem 2009; 284:12562-71. [PMID: 19270309 DOI: 10.1074/jbc.m901121200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the mammalian hippocampus, changes in the expression of immediate early genes (IEGs) is thought to contribute to long term plastic changes in neurons brought about by learning tasks and high frequency stimulation of synapses. The phosphatase calcineurin has emerged as an important negative regulator of hippocampus-dependent learning and long term potentiation. Here we investigated the possibility that the constraining action of calcineurin on hippocampal plasticity is mediated in part by regulation of gene expression through negative control of transcription factors, such as cAMP-response element (CRE)-binding protein (CREB). We assessed the effect of calcineurin inhibitors on CREB activation by neuronal activity and show that calcineurin activity is in fact required for CREB-mediated gene expression. However, inhibition of calcineurin had disparate effects on the transcriptional induction of CREB-dependent IEGs. We find that the IEG c-fos is unaffected by suppression of calcineurin activity, the plasticity-related genes Egr1/Zif268 and Egr2/Krox-20 are up-regulated, and genes encoding the orphan nuclear hormone receptors Nor1 and Nur77 are down-regulated. We further show that the up-regulation of particular IEGs is probably due to the presence of serum response elements (SREs) in their promoters, because SRE-mediated gene expression is enhanced by calcineurin blockers. Moreover, expression of the c-fos gene, which is unaffected by calcineurin inhibitors, could be down-regulated by mutating the SRE. Conversely, SRE-mediated c-fos induction in the absence of a functional CRE was enhanced by calcineurin inhibitors. Our experiments thus implicate calcineurin as a negative regulator of SRE-dependent neuronal genes.
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Affiliation(s)
- Brian Yee Hong Lam
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
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99
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Abstract
Most molecular and cellular studies of cognitive function have focused on either normal or pathological states, but recent research with transgenic mice has started to address the mechanisms of enhanced cognition. These results point to key synaptic and nuclear signalling events that can be manipulated to facilitate the induction or increase the stability of synaptic plasticity, and therefore enhance the acquisition or retention of information. Here, we review these surprising findings and explore their implications to both mechanisms of learning and memory and to ongoing efforts to develop treatments for cognitive disorders. These findings represent the beginning of a fundamental new approach in the study of enhanced cognition.
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Affiliation(s)
- Yong-Seok Lee
- Department of Neurobiology, Brain Research Institute, University of California, Los Angeles, California 90095, USA
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100
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Christie-Fougere MM, Darby-King A, Harley CW, McLean JH. Calcineurin inhibition eliminates the normal inverted U curve, enhances acquisition and prolongs memory in a mammalian 3'-5'-cyclic AMP-dependent learning paradigm. Neuroscience 2008; 158:1277-83. [PMID: 19041926 DOI: 10.1016/j.neuroscience.2008.11.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 11/04/2008] [Accepted: 11/05/2008] [Indexed: 01/26/2023]
Abstract
The role protein phosphatase 2B (calcineurin, CaN) plays in learning and memory has received a significant amount of attention due to its promotion of the dephosphorylation of 3'-5'-cyclic AMP response element binding protein (CREB). Researchers have ascertained that overexpression of CaN is associated with memory retention deficits [Foster TC, Sharrow KM, Masse JR, Norris CM, Kumar A (2001) Calcineurin links Ca(2+) dysregulation with brain aging. J Neurosci 21:4066-4073; Mansuy IM, Mayford M, Jacob B, Kandel ER, Bach ME (1998) Restricted and regulated overexpression reveals calcineurin as a key component in the transition from short-term to long-term memory. Cell 92:39-49], while CaN inhibition enhances learning and memory [Gerdjikov TV, Beninger RJ (2005) Differential effects of calcineurin inhibition and protein kinase A activation on nucleus accumbens amphetamine-produced conditioned place preference in rats. Eur J Neurosci 22:697-705; Ikegami S, Inokuchi K (2000) Antisense DNA against calcineurin facilitates memory in contextual fear conditioning by lowering the threshold for hippocampal long-term potentiation induction. Neuroscience 98:637-646]. The present study hypothesized that infusion of a CaN inhibitor (FK506) bilaterally into the olfactory bulbs of postnatal day 6 Sprague Dawley rat pups would prolong the duration of a conditioned odor preference and retard cyclic AMP response element binding protein dephosphorylation. A 2 mg/kg s.c. injection of isoproterenol (ISO, beta-adrenoceptor agonist) was paired with a 10 min exposure to peppermint and subsequently an infusion of FK506. Immunohistochemistry for phosphorylated 3'-5'-cyclic AMP response element binding protein (pCREB) revealed that unilateral infusion of FK506 resulted in an amplification of phosphorylated CREB in the olfactory bulb 40 min after training compared with saline-infused bulbs. Pups infused bilaterally with FK506 maintained a learned preference for peppermint 48, 72 and 96 h after training. CaN inhibition also modified the conventional inverted U curve obtained when ISO is used to replace stroking, as the unconditioned stimulus. When pups were infused with FK506, learning occurred with sub- and supra-optimal doses of ISO indicating that CaN overcomes non-optimal effects ISO may have on learning. We demonstrate that CaN inhibition can extend the duration of conditioned olfactory memory and may provide a target for memory prolongation that is superior to even phosphodiesterase inhibition observed in previous studies.
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Affiliation(s)
- M M Christie-Fougere
- Memorial University of Newfoundland, Newfoundland and Labrador, St. John's, Canada A1B 3V6
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