551
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Stuchlik A. Dynamic learning and memory, synaptic plasticity and neurogenesis: an update. Front Behav Neurosci 2014; 8:106. [PMID: 24744707 PMCID: PMC3978286 DOI: 10.3389/fnbeh.2014.00106] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 03/13/2014] [Indexed: 01/17/2023] Open
Abstract
Mammalian memory is the result of the interaction of millions of neurons in the brain and their coordinated activity. Candidate mechanisms for memory are synaptic plasticity changes, such as long-term potentiation (LTP). LTP is essentially an electrophysiological phenomenon manifested in hours-lasting increase on postsynaptic potentials after synapse tetanization. It is thought to ensure long-term changes in synaptic efficacy in distributed networks, leading to persistent changes in the behavioral patterns, actions and choices, which are often interpreted as the retention of information, i.e., memory. Interestingly, new neurons are born in the mammalian brain and adult hippocampal neurogenesis is proposed to provide a substrate for dynamic and flexible aspects of behavior such as pattern separation, prevention of interference, flexibility of behavior and memory resolution. This work provides a brief review on the memory and involvement of LTP and adult neurogenesis in memory phenomena.
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Affiliation(s)
- Ales Stuchlik
- Institute of Physiology, Academy of Sciences of the Czech Republic Prague, Czech Republic
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552
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Fropf R, Zhang J, Tanenhaus AK, Fropf WJ, Siefkes E, Yin JCP. Time of day influences memory formation and dCREB2 proteins in Drosophila. Front Syst Neurosci 2014; 8:43. [PMID: 24744705 PMCID: PMC3978337 DOI: 10.3389/fnsys.2014.00043] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 03/11/2014] [Indexed: 11/15/2022] Open
Abstract
Many biological phenomena oscillate under the control of the circadian system, exhibiting peaks and troughs of activity across the day/night cycle. In most animal models, memory formation also exhibits this property, but the underlying neuronal and molecular mechanisms remain unclear. The dCREB2 transcription factor shows circadian regulated oscillations in its activity, and has been shown to be important for both circadian biology and memory formation. We show that the time-of-day (TOD) of behavioral training affects Drosophila memory formation. dCREB2 exhibits complex changes in protein levels across the daytime and nighttime, and these changes in protein abundance are likely to contribute to oscillations in dCREB2 activity and TOD effects on memory formation.
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Affiliation(s)
- Robin Fropf
- Departments of Genetics, University of Wisconsin-Madison Madison, WI, USA ; Neuroscience Training Program, University of Wisconsin-Madison Madison, WI, USA
| | - Jiabin Zhang
- Departments of Genetics, University of Wisconsin-Madison Madison, WI, USA ; Neuroscience Training Program, University of Wisconsin-Madison Madison, WI, USA
| | - Anne K Tanenhaus
- Departments of Genetics, University of Wisconsin-Madison Madison, WI, USA ; Neuroscience Training Program, University of Wisconsin-Madison Madison, WI, USA
| | - Whitney J Fropf
- Departments of Genetics, University of Wisconsin-Madison Madison, WI, USA
| | - Ellen Siefkes
- Departments of Genetics, University of Wisconsin-Madison Madison, WI, USA
| | - Jerry C P Yin
- Departments of Genetics, University of Wisconsin-Madison Madison, WI, USA ; Department of Neurology, University of Wisconsin-Madison Madison, WI, USA
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553
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Howell KK, Monk BR, Carmack SA, Mrowczynski OD, Clark RE, Anagnostaras SG. Inhibition of PKC disrupts addiction-related memory. Front Behav Neurosci 2014; 8:70. [PMID: 24639635 PMCID: PMC3945752 DOI: 10.3389/fnbeh.2014.00070] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 02/19/2014] [Indexed: 01/20/2023] Open
Abstract
The atypical PKC isoforms, PKMζ and PKCλ have been proposed as integral substrates of long-term memory (LTM). Inhibition of these isoforms has recently been demonstrated to be sufficient for impairing the expression and maintenance of long-term potentiation. Additionally, the pseudosubstrate inhibitor, zeta inhibitory peptide (ZIP), which effectively blocks PKMζ and PKCλ, has previously been shown to disrupt associative memory; very little is known about its effects on pathological nonassociative forms of memory related to addiction. The neural and molecular substrates of memory and addiction have recently been argued to overlap. Here, we used ZIP to disrupt PKMζ and PKCλ activity to examine their role in cocaine sensitization, a nonassociative, addiction-related memory argued to underlie the transition from casual to pathological drug use. We examined the effects of both continuous and acute administration of ZIP. Even a single application of ZIP blocked the development of sensitization; sustained inhibition using osmotic pumps produced an almost complete blockade of sensitization. Further, a single application of ZIP was shown to reduce membrane-bound AMPAR expression. These results demonstrate a novel, critical role for the atypical PKC isoforms in nonassociative memory and cocaine addiction.
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Affiliation(s)
- Kristin K Howell
- Molecular Cognition Laboratory, Department of Psychology, University of California San Diego, La Jolla, CA, USA
| | - Bradley R Monk
- Molecular Cognition Laboratory, Department of Psychology, University of California San Diego, La Jolla, CA, USA
| | - Stephanie A Carmack
- Molecular Cognition Laboratory, Department of Psychology, University of California San Diego, La Jolla, CA, USA
| | - Oliver D Mrowczynski
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Robert E Clark
- Veterans Affairs Medical Center San Diego, CA, USA ; Department of Psychiatry, University of California San Diego, La Jolla, CA, USA
| | - Stephan G Anagnostaras
- Molecular Cognition Laboratory, Department of Psychology, University of California San Diego, La Jolla, CA, USA ; Program in Neurosciences, University of California San Diego, La Jolla, CA, USA
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554
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Wallace J. Calcium dysregulation, and lithium treatment to forestall Alzheimer's disease – a merging of hypotheses. Cell Calcium 2014; 55:175-81. [DOI: 10.1016/j.ceca.2014.02.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 01/20/2014] [Accepted: 02/05/2014] [Indexed: 12/20/2022]
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555
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Emery AC, Eiden MV, Eiden LE. Separate cyclic AMP sensors for neuritogenesis, growth arrest, and survival of neuroendocrine cells. J Biol Chem 2014; 289:10126-39. [PMID: 24567337 DOI: 10.1074/jbc.m113.529321] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dividing neuroendocrine cells differentiate into a neuronal-like phenotype in response to ligands activating G protein-coupled receptors, leading to the elevation of the second messenger cAMP. Growth factors that act at receptor tyrosine kinases, such as nerve growth factor, also cause differentiation. We report here that two aspects of cAMP-induced differentiation, neurite extension and growth arrest, are dissociable at the level of the sensors conveying the cAMP signal in PC12 and NS-1 cells. Following cAMP elevation, neuritogenic cyclic AMP sensor/Rapgef2 is activated for signaling to ERK to mediate neuritogenesis, whereas Epac2 is activated for signaling to the MAP kinase p38 to mediate growth arrest. Neither action of cAMP requires transactivation of TrkA, the receptor for NGF. In fact, the differentiating effects of NGF do not require activation of any of the cAMP sensors protein kinase A, Epac, or neuritogenic cyclic AMP sensor/Rapgef2 but, rather, depend on ERK and p38 activation via completely independent signaling pathways. Hence, cAMP- and NGF-dependent signaling for differentiation are also completely insulated from each other. Cyclic AMP and NGF also protect NS-1 cells from serum withdrawal-induced cell death, again by two wholly separate signaling mechanisms, PKA-dependent for cAMP and PKA-independent for NGF.
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556
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Schacher S, Hu JY. The less things change, the more they are different: contributions of long-term synaptic plasticity and homeostasis to memory. Learn Mem 2014; 21:128-34. [PMID: 24532836 PMCID: PMC3929853 DOI: 10.1101/lm.027326.112] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
An important cellular mechanism contributing to the strength and duration of memories is activity-dependent alterations in the strength of synaptic connections within the neural circuit encoding the memory. Reversal of the memory is typically correlated with a reversal of the cellular changes to levels expressed prior to the stimulation. Thus, for stimulus-induced changes in synapse strength and their reversals to be functionally relevant, cellular mechanisms must regulate and maintain synapse strength both prior to and after the stimuli inducing learning and memory. The strengths of synapses within a neural circuit at any given moment are determined by cellular and molecular processes initiated during development and those subsequently regulated by the history of direct activation of the neural circuit and system-wide stimuli such as stress or motivational state. The cumulative actions of stimuli and other factors on an already modified neural circuit are attenuated by homeostatic mechanisms that prevent changes in overall synaptic inputs and excitability above or below specific set points (synaptic scaling). The mechanisms mediating synaptic scaling prevent potential excitotoxic alterations in the circuit but also may attenuate additional cellular changes required for learning and memory, thereby apparently limiting information storage. What cellular and molecular processes control synaptic strengths before and after experience/activity and its reversals? In this review we will explore the synapse-, whole cell-, and circuit level-specific processes that contribute to an overall zero sum-like set of changes and long-term maintenance of synapse strengths as a consequence of the accommodative interactions between long-term synaptic plasticity and homeostasis.
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Affiliation(s)
- Samuel Schacher
- Department of Neuroscience, Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute, New York, New York 10032, USA
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557
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Nelson EE, Lau JYF, Jarcho JM. Growing pains and pleasures: how emotional learning guides development. Trends Cogn Sci 2014; 18:99-108. [PMID: 24405846 PMCID: PMC4219354 DOI: 10.1016/j.tics.2013.11.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 11/14/2013] [Accepted: 11/15/2013] [Indexed: 12/23/2022]
Abstract
The nervous system promotes adaptive responding to myriad environmental stimuli by ascribing emotion to specific stimulus domains. This affects the salience of different stimuli, facilitates learning, and likely involves the amygdala. Recent studies suggest a strong homology between adaptive responses that result from learning and those that emerge during development. As in motivated learning, developmental studies have found the salience of different classes of stimulus (e.g., peers) undergoes marked fluctuation across maturation and may involve differential amygdala engagement. In this review, by highlighting the importance of particular stimulus categories during sensitive periods of development, we suggest that variability in amygdala response to different stimulus domains has an active and functional role in shaping emerging cortical circuits across development.
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Affiliation(s)
- Eric E Nelson
- Section on Development and Affective Neuroscience, National Institute of Mental Health, Bethesda MD, USA.
| | - Jennifer Y F Lau
- Department of Psychology, Institute of Psychiatry, King's College, London, UK
| | - Johanna M Jarcho
- Section on Development and Affective Neuroscience, National Institute of Mental Health, Bethesda MD, USA
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558
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Rudenko A, Tsai LH. Epigenetic modifications in the nervous system and their impact upon cognitive impairments. Neuropharmacology 2014; 80:70-82. [PMID: 24495398 DOI: 10.1016/j.neuropharm.2014.01.043] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 01/23/2014] [Accepted: 01/24/2014] [Indexed: 12/13/2022]
Abstract
Epigenetic regulation has been long considered to be a critical mechanism in the control of key aspects of cellular functions such as cell division, growth, and cell fate determination. Exciting recent developments have demonstrated that epigenetic mechanisms can also play necessary roles in the nervous system by regulating, for example, neuronal gene expression, DNA damage, and genome stability. Despite the fact that postmitotic neurons are developmentally less active then dividing cells, epigenetic regulation appears to provide means of both long-lasting and very dynamic regulation of neuronal function. Growing evidence indicates that epigenetic mechanisms in the central nervous system (CNS) are important for regulating not only specific aspects of individual neuronal metabolism but also for maintaining function of neuronal circuits and regulating their behavioral outputs. Multiple reports demonstrated that higher-level cognitive behaviors, such as learning and memory, are subject to a sophisticated epigenetic control, which includes interplay between multiple mechanisms of neuronal chromatin modification. Experiments with animal models have demonstrated that various epigenetic manipulations can affect cognition in different ways, from severe dysfunction to substantial improvement. In humans, epigenetic dysregulation has been known to underlie a number of disorders that are accompanied by mental impairment. Here, we review some of the epigenetic mechanisms that regulate cognition and how their disruption may contribute to cognitive dysfunctions. Due to the fact that histone acetylation and DNA methylation are some of the best-studied and critically important epigenomic modifications our research team has particularly strong expertise in, in this review, we are going to concentrate on histone acetylation, as well as DNA methylation/hydroxymethylation, in the mammalian CNS. Additional epigenetic modifications, not surveyed here, are being discussed in depth in the other review articles in this issue of Neuropharmacology.
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Affiliation(s)
- Andrii Rudenko
- Picower Institute for Learning and Memory, Howard Hughes Medical Institute, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Li-Huei Tsai
- Picower Institute for Learning and Memory, Howard Hughes Medical Institute, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
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559
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Abstract
The exchange of CaMKII enzymes between larger structures called holoenzymes may provide the molecular mechanism underlying the long-term stability of memories.
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Affiliation(s)
- John E Lisman
- John E Lisman is in the Biology Department and Volen Center for Complex Systems, Brandeis University, Waltham, United States
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560
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Sable P, Kale A, Joshi A, Joshi S. Maternal micronutrient imbalance alters gene expression of BDNF, NGF, TrkB and CREB in the offspring brain at an adult age. Int J Dev Neurosci 2014; 34:24-32. [PMID: 24462543 DOI: 10.1016/j.ijdevneu.2014.01.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 01/07/2014] [Accepted: 01/13/2014] [Indexed: 01/08/2023] Open
Abstract
Micronutrients like folate, vitamin B12, and fatty acids which are interlinked in the one carbon cycle play a vital role in mediating epigenetic processes leading to an increased risk for neurodevelopmental disorders in the offspring. Our earlier study demonstrates that a micronutrient imbalanced diet adversely affects docosahexaenoic acid (DHA) and protein levels of neurotrophins like brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in the brain and cognition in the offspring by 3 months of age. In this study we attempt to analyze if these effects are a consequence of a change in gene expression of these molecules. Further, we also examined the effect of either a postnatal control diet or a prenatal omega-3 fatty acid supplementation on gene expression in the cortex of the offspring. Pregnant rats were divided into control and five treatment groups at two levels of folic acid (normal and excess folate) in the presence and absence of vitamin B12. Omega-3 fatty acid (eicosapentaenoic acid - EPA+DHA) supplementation was given to vitamin B12 deficient groups. Following delivery, 8 dams from each group were shifted to control diet and remaining continued on the same treatment diet. Our results demonstrate that the imbalanced diet caused a marked reduction in the mRNA levels of BDNF, NGF, TrkB, and cAMP response element-binding protein (CREB). Prenatal omega-3 fatty acid supplementation to the maternal imbalanced diet was able to normalize the mRNA levels of all the above genes. This study demonstrates that a maternal diet imbalanced in micronutrients (folic acid, vitamin B12) influences gene expression of neurotrophins and their signalling molecules and thereby adversely affects the brain of the offspring.
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Affiliation(s)
- Pratiksha Sable
- Department of Nutritional Medicine, Interactive Research School for Health Affairs, Bharati Vidyapeeth Deemed University, Pune Satara Road, Pune 411043, India
| | - Anvita Kale
- Department of Nutritional Medicine, Interactive Research School for Health Affairs, Bharati Vidyapeeth Deemed University, Pune Satara Road, Pune 411043, India
| | - Asmita Joshi
- Department of Nutritional Medicine, Interactive Research School for Health Affairs, Bharati Vidyapeeth Deemed University, Pune Satara Road, Pune 411043, India
| | - Sadhana Joshi
- Department of Nutritional Medicine, Interactive Research School for Health Affairs, Bharati Vidyapeeth Deemed University, Pune Satara Road, Pune 411043, India.
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561
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d'Isa R, Brambilla R, Fasano S. Behavioral methods for the study of the Ras-ERK pathway in memory formation and consolidation: passive avoidance and novel object recognition tests. Methods Mol Biol 2014; 1120:131-156. [PMID: 24470023 DOI: 10.1007/978-1-62703-791-4_9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Memory is a high-level brain function that enables organisms to adapt their behavioral responses to the environment, hence increasing their probability of survival. The Ras-ERK pathway is a key molecular intracellular signalling cascade for memory consolidation. In this chapter we will describe two main one-trial behavioral tests commonly used in the field of memory research in order to assess the role of Ras-ERK signalling in long-term memory: passive avoidance and object recognition. Passive avoidance (PA) is a fear-motivated instrumental learning task, designed by Jarvik and Essman in 1960, in which animals learn to refrain from emitting a behavioral response that has previously been associated with a punishment. We will describe here the detailed protocol and show some examples of how PA can reveal impairments or enhancements in memory consolidation following loss or gain of function genetic manipulations of the Ras-ERK pathway. The phenotypes of global mutants as Ras-GRF1 KO, GENA53, and ERK1 KO mice, as well as of conditional region-specific mutants (striatal K-CREB mice), will be illustrated as examples. Novel object recognition (NOR), developed by Ennaceur and Delacour in 1988, is instead a more recent and highly ecological test, which relies on the natural tendency of rodents to spontaneously approach and explore novel objects, representing hence a useful non-stressful tool for the study of memory in animals without the employment of punishments or starvation/water restriction regimens. Careful indications will be given on how to select the positions for the novel object, in order to counterbalance for individual side preferences among mice during the training. Finally, the methods for calculating two learning indexes will be described. In addition to the classical discrimination index (DI) that measures the ability of an animal to discriminate between two different objects which are presented at the same time, we will describe the formula of a new index that we present here for the first time, the recognition index (RI), which quantifies the ability of an animal to recognize a same object at different time points and that, by taking into account the basal individual preferences displayed during the training, can give a more accurate measure of an animal's actual recognition memory.
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Affiliation(s)
- Raffaele d'Isa
- Division of Neuroscience, Institute of Experimental Neurology, San Raffaele Scientific Institute and University, Milan, Italy
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562
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Bisaz R, Travaglia A, Alberini CM. The neurobiological bases of memory formation: from physiological conditions to psychopathology. Psychopathology 2014; 47:347-56. [PMID: 25301080 PMCID: PMC4246028 DOI: 10.1159/000363702] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 05/17/2014] [Indexed: 12/28/2022]
Abstract
The formation of long-term memories is a function necessary for an adaptive survival. In the last two decades, great progress has been made in the understanding of the biological bases of memory formation. The identification of mechanisms necessary for memory consolidation and reconsolidation, the processes by which the posttraining and postretrieval fragile memory traces become stronger and insensitive to disruption, has indicated new approaches for investigating and treating psychopathologies. In this review, we will discuss some key biological mechanisms found to be critical for memory consolidation and strengthening, the role/s and mechanisms of memory reconsolidation, and how the interference with consolidation and/or reconsolidation can modulate the retention and/or storage of memories that are linked to psychopathologies.
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Affiliation(s)
- Reto Bisaz
- Center for Neural Science, New York University, New York, N.Y., USA
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563
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Beyeler A, Eckhardt CA, Tye KM. Deciphering Memory Function with Optogenetics. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 122:341-90. [DOI: 10.1016/b978-0-12-420170-5.00012-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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564
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Fitzsimons HL, Schwartz S, Given FM, Scott MJ. The histone deacetylase HDAC4 regulates long-term memory in Drosophila. PLoS One 2013; 8:e83903. [PMID: 24349558 PMCID: PMC3857321 DOI: 10.1371/journal.pone.0083903] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Accepted: 11/09/2013] [Indexed: 12/22/2022] Open
Abstract
A growing body of research indicates that pharmacological inhibition of histone deacetylases (HDACs) correlates with enhancement of long-term memory and current research is concentrated on determining the roles that individual HDACs play in cognitive function. Here, we investigate the role of HDAC4 in long-term memory formation in Drosophila. We show that overexpression of HDAC4 in the adult mushroom body, an important structure for memory formation, resulted in a specific impairment in long-term courtship memory, but had no affect on short-term memory. Overexpression of an HDAC4 catalytic mutant also abolished LTM, suggesting a mode of action independent of catalytic activity. We found that overexpression of HDAC4 resulted in a redistribution of the transcription factor MEF2 from a relatively uniform distribution through the nucleus into punctate nuclear bodies, where it colocalized with HDAC4. As MEF2 has also been implicated in regulation of long-term memory, these data suggest that the repressive effects of HDAC4 on long-term memory may be through interaction with MEF2. In the same genetic background, we also found that RNAi-mediated knockdown of HDAC4 impairs long-term memory, therefore we demonstrate that HDAC4 is not only a repressor of long-term memory, but also modulates normal memory formation.
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Affiliation(s)
- Helen L. Fitzsimons
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
- * E-mail:
| | - Silvia Schwartz
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Fiona M. Given
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Maxwell J. Scott
- Department of Entomology, North Carolina State University, Raleigh, North Carolina, United States of America
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565
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Park P, Volianskis A, Sanderson TM, Bortolotto ZA, Jane DE, Zhuo M, Kaang BK, Collingridge GL. NMDA receptor-dependent long-term potentiation comprises a family of temporally overlapping forms of synaptic plasticity that are induced by different patterns of stimulation. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130131. [PMID: 24298134 PMCID: PMC3843864 DOI: 10.1098/rstb.2013.0131] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
N-methyl-d-aspartate receptor (NMDAR)-dependent long-term potentiation (LTP) is extensively studied since it is believed to use the same molecular mechanisms that are required for many forms of learning and memory. Unfortunately, many controversies exist, not least the seemingly simple issue concerning the locus of expression of LTP. Here, we review our recent work and some of the extensive literature on this topic and present new data that collectively suggest that LTP can be explained, during its first few hours, by the coexistence of at least three mechanistically distinct processes that are all triggered by the synaptic activation of NMDARs.
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Affiliation(s)
- Pojeong Park
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, , Seoul 151-746, South Korea
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566
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Tabakoff B, Hoffman PL. The neurobiology of alcohol consumption and alcoholism: an integrative history. Pharmacol Biochem Behav 2013; 113:20-37. [PMID: 24141171 PMCID: PMC3867277 DOI: 10.1016/j.pbb.2013.10.009] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 10/09/2013] [Accepted: 10/10/2013] [Indexed: 01/17/2023]
Abstract
Studies of the neurobiological predisposition to consume alcohol (ethanol) and to transition to uncontrolled drinking behavior (alcoholism), as well as studies of the effects of alcohol on brain function, started a logarithmic growth phase after the repeal of the 18th Amendment to the United States Constitution. Although the early studies were primitive by current technological standards, they clearly demonstrated the effects of alcohol on brain structure and function, and by the end of the 20th century left little doubt that alcoholism is a "disease" of the brain. This review traces the history of developments in the understanding of ethanol's effects on the most prominent inhibitory and excitatory systems of brain (GABA and glutamate neurotransmission). This neurobiological information is integrated with knowledge of ethanol's actions on other neurotransmitter systems to produce an anatomical and functional map of ethanol's properties. Our intent is limited in scope, but is meant to provide context and integration of the actions of ethanol on the major neurobiologic systems which produce reinforcement for alcohol consumption and changes in brain chemistry that lead to addiction. The developmental history of neurobehavioral theories of the transition from alcohol drinking to alcohol addiction is presented and juxtaposed to the neurobiological findings. Depending on one's point of view, we may, at this point in history, know more, or less, than we think we know about the neurobiology of alcoholism.
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Affiliation(s)
- Boris Tabakoff
- University of Colorado School of Medicine, MS8303, 12800 E. 19 Ave., Aurora, CO 80045 U.S.A
| | - Paula L. Hoffman
- University of Colorado School of Medicine, MS8303, 12800 E. 19 Ave., Aurora, CO 80045 U.S.A
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567
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Podda MV, Grassi C. New perspectives in cyclic nucleotide-mediated functions in the CNS: the emerging role of cyclic nucleotide-gated (CNG) channels. Pflugers Arch 2013; 466:1241-57. [PMID: 24142069 DOI: 10.1007/s00424-013-1373-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Revised: 09/27/2013] [Accepted: 09/28/2013] [Indexed: 01/07/2023]
Abstract
Cyclic nucleotides play fundamental roles in the central nervous system (CNS) under both physiological and pathological conditions. The impact of cAMP and cGMP signaling on neuronal and glial cell functions has been thoroughly characterized. Most of their effects have been related to cyclic nucleotide-dependent protein kinase activity. However, cyclic nucleotide-gated (CNG) channels, first described as key mediators of sensory transduction in retinal and olfactory receptors, have been receiving increasing attention as possible targets of cyclic nucleotides in the CNS. In the last 15 years, consistent evidence has emerged for their expression in neurons and astrocytes of the rodent brain. Far less is known, however, about the functional role of CNG channels in these cells, although several of their features, such as Ca(2+) permeability and prolonged activation in the presence of cyclic nucleotides, make them ideal candidates for mediators of physiological functions in the CNS. Here, we review literature suggesting the involvement of CNG channels in a number of CNS cellular functions (e.g., regulation of membrane potential, neuronal excitability, and neurotransmitter release) as well as in more complex phenomena, like brain plasticity, adult neurogenesis, and pain sensitivity. The emerging picture is that functional and dysfunctional cyclic nucleotide signaling in the CNS has to be reconsidered including CNG channels among possible targets. However, concerted efforts and multidisciplinary approaches are still needed to get more in-depth knowledge in this field.
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Affiliation(s)
- Maria Vittoria Podda
- Institute of Human Physiology, Medical School, Università Cattolica, Largo Francesco Vito 1, 00168, Rome, Italy
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568
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Roles for NF-κB and gene targets of NF-κB in synaptic plasticity, memory, and navigation. Mol Neurobiol 2013; 49:757-70. [PMID: 24122352 DOI: 10.1007/s12035-013-8555-y] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 09/19/2013] [Indexed: 01/04/2023]
Abstract
Although traditionally associated with immune function, the transcription factor nuclear factor kappa B (NF-κB) has garnered much attention in recent years as an important regulator of memory. Specifically, research has found that NF-κB, localized in both neurons and glia, is activated during the induction of long-term potentiation (LTP), a paradigm of synaptic plasticity and correlate of memory. Further, experimental manipulation of NF-κB activation or its blockade results in altered memory and spatial navigation abilities. Genetic knockout of specific NF-κB subunits in mice results in memory alterations. Collectively, such data suggest that NF-κB may be a requirement for memory, although the direction of the response (i.e., memory enhancement or deficit) is inconsistent. A limited number of gene targets of NF-κB have been recently identified in neurons, including neurotrophic factors, calcium-regulating proteins, other transcription factors, and molecules associated with neuronal outgrowth and remodeling. In turn, several key molecules are activators of NF-κB, including protein kinase C and [Ca(++)]i. Thus, NF-κB signaling is complex and under the regulation of numerous proteins involved in activity-dependent synaptic plasticity. The purpose of this review is to highlight the literature detailing a role for NF-κB in synaptic plasticity, memory, and spatial navigation. Secondly, this review will synthesize the research evaluating gene targets of NF-κB in synaptic plasticity and memory. Although there is ample evidence to suggest a critical role for NF-κB in memory, our understanding of its gene targets in neurons is limited and only beginning to be appreciated.
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569
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570
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Affiliation(s)
- Jonathon D. Crystal
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - David L. Glanzman
- Departments of Integrative Biology and Physiology, and Neurobiology, and the Integrative Center for Learning and Memory, University of California, Los Angeles, CA 90095, USA
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571
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O'Neale A, Ellis J, Creton R, Colwill RM. Single stimulus learning in zebrafish larvae. Neurobiol Learn Mem 2013; 108:145-54. [PMID: 24012906 DOI: 10.1016/j.nlm.2013.08.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 08/19/2013] [Accepted: 08/29/2013] [Indexed: 11/30/2022]
Abstract
Learning about a moving visual stimulus was examined in zebrafish larvae using an automated imaging system and a t1-t2 design. In three experiments, zebrafish larvae were exposed to one of two inputs at t1 (either a gray bouncing disk or an identical but stationary disk) followed by a common test at t2 (the gray bouncing disk). Using 7days post-fertilization (dpf) larvae and 12 stimulus exposures, Experiment 1 established that these different treatments produced differential responding to the moving disk during testing. Larvae familiar with the moving test stimulus were significantly less likely to be still in its presence than larvae that had been exposed to the identical but stationary stimulus. Experiment 2 confirmed this result in 7dpf larvae and extended the finding to 5 and 6dpf larvae. Experiment 3 found differential responding to the moving test stimulus with 4 or 8 stimulus exposures but not with just one exposure in 7dpf larvae. These results provide evidence for learning in very young zebrafish larvae. The merits and challenges of the t1-t2 framework to study learning are discussed.
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Affiliation(s)
- Ashley O'Neale
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI, USA
| | - Joseph Ellis
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI, USA
| | - Robbert Creton
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, USA
| | - Ruth M Colwill
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI, USA.
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572
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Saha RN, Dudek SM. Splitting hares and tortoises: a classification of neuronal immediate early gene transcription based on poised RNA polymerase II. Neuroscience 2013; 247:175-81. [PMID: 23711585 PMCID: PMC3722259 DOI: 10.1016/j.neuroscience.2013.04.064] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 04/19/2013] [Accepted: 04/20/2013] [Indexed: 01/06/2023]
Abstract
Immediate early transcription is an integral part of the neuronal response to environmental stimulation and serves many brain processes including development, learning, triggers of programmed cell death, and reaction to injury and drugs. Following a stimulus, neurons express a select few genes within a short period of time without undergoing de novo protein translation. Referred to as the 'gateway to genetic response', these immediate early genes (IEGs) are either expressed within a few minutes of stimulation or later within the hour. In neuronal IEGs that are expressed rapidly, productive elongation in response to neuronal activity is jump-started by constitutive transcription initiation together with RNA polymerase II stalling in the vicinity of the promoter. IEGs expressed later in the hour do not depend on this mechanism. On the basis of this Polymerase II poising, we propose that the immediate early genes can be grouped in two distinct classes: the rapid and the delayed IEGs. The possible biological relevance of these classes in neurons is discussed.
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Affiliation(s)
- R N Saha
- Synaptic and Developmental Plasticity Group, Laboratory of Neurobiology, NIEHS, NIH, 111 TW Alexander Drive, Research Triangle Park, NC 27709, United States
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573
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Wu W, Yu X, Luo XP, Yang SH, Zheng D. Tetramethylpyrazine protects against scopolamine-induced memory impairments in rats by reversing the cAMP/PKA/CREB pathway. Behav Brain Res 2013; 253:212-6. [PMID: 23916742 DOI: 10.1016/j.bbr.2013.07.052] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 07/26/2013] [Accepted: 07/30/2013] [Indexed: 10/26/2022]
Abstract
Tetramethylpyrazine is used in the treatment of many neurological diseases because of its neuroprotective effect. Here, we demonstrate that administration of tetramethylpyrazine effectively reverses memory deficits induced by scopolamine. Moreover, tetramethylpyrazine preserves postsynaptic protein synthesis and restores cAMP/PKA/CREB pathway signaling deficits. Our study not only explores the actions of tetramethylpyrazine on synapses, but also provides novel evidence for the possible therapeutic use of tetramethylpyrazine in dementia.
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Affiliation(s)
- Wei Wu
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, PR China
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574
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Affiliation(s)
- Alexander Thiele
- Institute of Neuroscience, Henry Wellcome Building, Newcastle University, Newcastle upon Tyne, NE2 4HH, United Kingdom;
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575
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Very long-term memories may be stored in the pattern of holes in the perineuronal net. Proc Natl Acad Sci U S A 2013; 110:12456-61. [PMID: 23832785 DOI: 10.1073/pnas.1310158110] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A hypothesis and the experiments to test it propose that very long-term memories, such as fear conditioning, are stored as the pattern of holes in the perineuronal net (PNN), a specialized ECM that envelops mature neurons and restricts synapse formation. The 3D intertwining of PNN and synapses would be imaged by serial-section EM. Lifetimes of PNN vs. intrasynaptic components would be compared with pulse-chase (15)N labeling in mice and (14)C content in human cadaver brains. Genetically encoded indicators and antineoepitope antibodies should improve spatial and temporal resolution of the in vivo activity of proteases that locally erode PNN. Further techniques suggested include genetic KOs, better pharmacological inhibitors, and a genetically encoded snapshot reporter, which will capture the pattern of activity throughout a large ensemble of neurons at a time precisely defined by the triggering illumination, drive expression of effector genes to mark those cells, and allow selective excitation, inhibition, or ablation to test their functional importance. The snapshot reporter should enable more precise inhibition or potentiation of PNN erosion to compare with behavioral consequences. Finally, biosynthesis of PNN components and proteases would be imaged.
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576
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Trinh AT, Kim SH, Chang HY, Mastrocola AS, Tibbetts RS. Cyclin-dependent kinase 1-dependent phosphorylation of cAMP response element-binding protein decreases chromatin occupancy. J Biol Chem 2013; 288:23765-75. [PMID: 23814058 DOI: 10.1074/jbc.m113.464057] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cyclic AMP response element-binding protein (CREB) initiates transcriptional responses to a wide variety of stimuli. CREB activation involves its phosphorylation on Ser-133, which promotes interaction between the CREB kinase-inducible domain (KID) and the KID-interacting domain of the transcriptional coactivator, CREB-binding protein (CBP). The KID also contains a highly conserved phosphorylation cluster, termed the ATM/CK cluster, which is processively phosphorylated in response to DNA damage by the coordinated actions of ataxia-telangiectasia-mutated (ATM) and casein kinases (CKs) 1 and 2. The ATM/CK cluster phosphorylation attenuates CBP binding and CREB transcriptional activity. Paradoxically, it was recently reported that DNA damage activates CREB through homeodomain-interacting protein kinase 2-dependent phosphorylation of Ser-271 near the CREB bZIP DNA binding domain. In this study we sought to further clarify DNA damage-dependent CREB phosphorylation as well as to explore the possibility that the ATM/CK cluster and Ser-271 synergistically or antagonistically modulate CREB activity. We show that, rather than being induced by DNA damage, Ser-270 and Ser-271 of CREB cophosphorylated in a CDK1-dependent manner during G2/M phase. Functionally, we show that phosphorylation of CREB on Ser-270/Ser-271 during mitosis correlated with reduced CREB chromatin occupancy. Furthermore, CDK1-dependent phosphorylation of CREB in vitro inhibited its DNA binding activity. The combined results suggest that CDK1-dependent phosphorylation of CREB on Ser-270/Ser-271 facilitates its dissociation from chromatin during mitosis by reducing its intrinsic DNA binding potential.
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Affiliation(s)
- Anthony T Trinh
- Department of Human Oncology, Program in Molecular and Cellular Pharmacology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705, USA
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577
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Modi KK, Sendtner M, Pahan K. Up-regulation of ciliary neurotrophic factor in astrocytes by aspirin: implications for remyelination in multiple sclerosis. J Biol Chem 2013; 288:18533-45. [PMID: 23653362 DOI: 10.1074/jbc.m112.447268] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Ciliary neurotrophic factor (CNTF) is a promyelinating trophic factor, and the mechanisms by which CNTF expression could be increased in the brain are poorly understood. Acetylsalicylic acid (aspirin) is one of the most widely used analgesics. Interestingly, aspirin increased mRNA and protein expression of CNTF in primary mouse and human astrocytes in a dose- and time-dependent manner. Aspirin induced the activation of protein kinase A (PKA) but not protein kinase C (PKC). H-89, an inhibitor of PKA, abrogated aspirin-induced expression of CNTF. The activation of cAMP-response element-binding protein (CREB), but not NF-κB, by aspirin, the abrogation of aspirin-induced expression of CNTF by siRNA knockdown of CREB, the presence of a consensus cAMP-response element in the promoter of CNTF, and the recruitment of CREB and CREB-binding protein to the CNTF promoter by aspirin suggest that aspirin increases the expression of the Cntf gene via the activation of CREB. Furthermore, we demonstrate that aspirin-induced astroglial CNTF was also functionally active and that supernatants of aspirin-treated astrocytes of wild type, but not Cntf null, mice increased myelin-associated proteins in oligodendrocytes and protected oligodendrocytes from TNF-α insult. These results highlight a new and novel myelinogenic property of aspirin, which may be of benefit for multiple sclerosis and other demyelinating disorders.
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Affiliation(s)
- Khushbu K Modi
- Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois 60612, USA
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578
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Drosophila ORB protein in two mushroom body output neurons is necessary for long-term memory formation. Proc Natl Acad Sci U S A 2013; 110:7898-903. [PMID: 23610406 DOI: 10.1073/pnas.1216336110] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Memory is initially labile and gradually consolidated over time through new protein synthesis into a long-lasting stable form. Studies of odor-shock associative learning in Drosophila have established the mushroom body (MB) as a key brain structure involved in olfactory long-term memory (LTM) formation. Exactly how early neural activity encoded in thousands of MB neurons is consolidated into protein-synthesis-dependent LTM remains unclear. Here, several independent lines of evidence indicate that changes in two MB vertical lobe V3 (MB-V3) extrinsic neurons are required and contribute to an extended neural network involved in olfactory LTM: (i) inhibiting protein synthesis in MB-V3 neurons impairs LTM; (ii) MB-V3 neurons show enhanced neural activity after spaced but not massed training; (iii) MB-V3 dendrites, synapsing with hundreds of MB α/β neurons, exhibit dramatic structural plasticity after removal of olfactory inputs; (iv) neurotransmission from MB-V3 neurons is necessary for LTM retrieval; and (v) RNAi-mediated down-regulation of oo18 RNA-binding protein (involved in local regulation of protein translation) in MB-V3 neurons impairs LTM. Our results suggest a model of long-term memory formation that includes a systems-level consolidation process, wherein an early, labile olfactory memory represented by neural activity in a sparse subset of MB neurons is converted into a stable LTM through protein synthesis in dendrites of MB-V3 neurons synapsed onto MB α lobes.
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579
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Kim J, Kwon JT, Kim HS, Han JH. CREB and neuronal selection for memory trace. Front Neural Circuits 2013; 7:44. [PMID: 23519079 PMCID: PMC3604628 DOI: 10.3389/fncir.2013.00044] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Accepted: 03/03/2013] [Indexed: 11/13/2022] Open
Abstract
Despite considerable progress over the past several decades, our understanding of the mechanisms underlying memory encoding, storage, and expression in a complex neural network are far from complete. In particular, how some neurons rather than others are selectively engaged to encode memory remains largely unknown. Using virus-mediated gene delivery into a small subset of neurons in a given network, molecular imaging of neuronal activity, pharmacological perturbation of specific neurons' activity and animal behavior assays, recent studies have begun to provide insight into molecular and cellular mechanisms responsible for the selection of neurons for inclusion into a memory trace. Here, we focus on a review of recent findings supporting the hypothesis that the level of the transcription factor CREB (cAMP/Ca2+-response element binding protein) is a key factor governing which neurons are recruited to a given memory trace. These recent findings open a new perspective on memory trace at the neural circuit level and also raise many important questions. Future studies employing more advanced neurobiological techniques for targeting defined populations of neurons and manipulating their activity in time and space in a complex neural network will give answers to these newly emerging questions and extend our understanding of the neurobiological basis of the memory trace.
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Affiliation(s)
- Jieun Kim
- Laboratory of Neural Circuit and Behavior, Department of Biological Sciences, KAIST Institute for the BioCentury, Korea Advanced Institute of Science and Technology Daejeon, Korea
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580
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Arencibia JM, Pastor-Flores D, Bauer AF, Schulze JO, Biondi RM. AGC protein kinases: from structural mechanism of regulation to allosteric drug development for the treatment of human diseases. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:1302-21. [PMID: 23524293 DOI: 10.1016/j.bbapap.2013.03.010] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 03/07/2013] [Indexed: 01/15/2023]
Abstract
The group of AGC protein kinases includes more than 60 protein kinases in the human genome, classified into 14 families: PDK1, AKT/PKB, SGK, PKA, PKG, PKC, PKN/PRK, RSK, NDR, MAST, YANK, DMPK, GRK and SGK494. This group is also widely represented in other eukaryotes, including causative organisms of human infectious diseases. AGC kinases are involved in diverse cellular functions and are potential targets for the treatment of human diseases such as cancer, diabetes, obesity, neurological disorders, inflammation and viral infections. Small molecule inhibitors of AGC kinases may also have potential as novel therapeutic approaches against infectious organisms. Fundamental in the regulation of many AGC kinases is a regulatory site termed the "PIF-pocket" that serves as a docking site for substrates of PDK1. This site is also essential to the mechanism of activation of AGC kinases by phosphorylation and is involved in the allosteric regulation of N-terminal domains of several AGC kinases, such as PKN/PRKs and atypical PKCs. In addition, the C-terminal tail and its interaction with the PIF-pocket are involved in the dimerization of the DMPK family of kinases and may explain the molecular mechanism of allosteric activation of GRKs by GPCR substrates. In this review, we briefly introduce the AGC kinases and their known roles in physiology and disease and the discovery of the PIF-pocket as a regulatory site in AGC kinases. Finally, we summarize the current status and future therapeutic potential of small molecules directed to the PIF-pocket; these molecules can allosterically activate or inhibit the kinase as well as act as substrate-selective inhibitors. This article is part of a Special Issue entitled: Inhibitors of Protein Kinases (2012).
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Affiliation(s)
- José M Arencibia
- Research Group PhosphoSites, Department of Internal Medicine I, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
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581
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Wallace J. Treatment of trauma with lithium to forestall the development of posttraumatic stress disorder by pharmacological induction of a mild transient amnesia. Med Hypotheses 2013; 80:711-5. [PMID: 23490200 DOI: 10.1016/j.mehy.2013.02.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 02/04/2013] [Accepted: 02/16/2013] [Indexed: 11/15/2022]
Abstract
Posttraumatic stress disorder (PTSD) is a severe anxiety disorder that develops after exposure to trauma. Symptoms include persistent reexperiencing, persistent avoidance, persistent numbing, and persistent hyperarousal. Subsequent to trauma exposure, the onset of symptoms of an acute stress reaction can typically develop over varying amounts of time from days to months. Current pharmacotherapies for PTSD are available after symptoms manifest, and primarily consist of selective serotonin reuptake inhibitor (SSRI) antidepressants. There are currently no FDA approved pharmacological interventions available for the treatment of acutely traumatized individuals to forestall the development of PTSD after trauma and prior to the onset of symptoms. A prominent model of PTSD developed by Roger Pitman attributes the pathogenesis of PTSD to over-consolidated traumatic memories that are mediated by endogenous stress hormones released with trauma and after trauma. The molecular processes of memory consolidation in neurons are mediated by intracellular signaling pathways. One secondary messenger signaling pathway with a putative role in long-term potentiation (LTP) is the inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG) secondary messenger system. Lithium, a treatment for bipolar disorder, and a pharmacotherapy that is associated with inducing transient impairments in cognition, memory, and learning, is an inhibitor of inositol monophosphatase (IMP), an enzyme in the IP3 and DAG secondary messenger pathway. I am advancing the hypothesis that the administration of lithium for a brief interval to traumatized individuals at risk for PTSD within the time period after trauma and prior to the onset of symptoms could potentially forestall the development of PTSD by disrupting LTP. I am proposing that this treatment will reduce the incidence of PTSD and reduce the severity of symptoms in those who eventually develop PTSD.
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Affiliation(s)
- James Wallace
- The Aging and Dementia Research Center, New York University School of Medicine, 145 East 32nd Street, New York, NY 10016, USA.
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582
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Up-regulation of neurotrophic factors by cinnamon and its metabolite sodium benzoate: therapeutic implications for neurodegenerative disorders. J Neuroimmune Pharmacol 2013; 8:739-55. [PMID: 23475543 DOI: 10.1007/s11481-013-9447-7] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 02/26/2013] [Indexed: 10/27/2022]
Abstract
This study underlines the importance of cinnamon, a widely-used food spice and flavoring material, and its metabolite sodium benzoate (NaB), a widely-used food preservative and a FDA-approved drug against urea cycle disorders in humans, in increasing the levels of neurotrophic factors [e.g., brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3)] in the CNS. NaB, but not sodium formate (NaFO), dose-dependently induced the expression of BDNF and NT-3 in primary human neurons and astrocytes. Interestingly, oral administration of ground cinnamon increased the level of NaB in serum and brain and upregulated the levels of these neurotrophic factors in vivo in mouse CNS. Accordingly, oral feeding of NaB, but not NaFO, also increased the level of these neurotrophic factors in vivo in the CNS of mice. NaB induced the activation of protein kinase A (PKA), but not protein kinase C (PKC), and H-89, an inhibitor of PKA, abrogated NaB-induced increase in neurotrophic factors. Furthermore, activation of cAMP response element binding (CREB) protein, but not NF-κB, by NaB, abrogation of NaB-induced expression of neurotrophic factors by siRNA knockdown of CREB and the recruitment of CREB and CREB-binding protein to the BDNF promoter by NaB suggest that NaB exerts its neurotrophic effect through the activation of CREB. Accordingly, cinnamon feeding also increased the activity of PKA and the level of phospho-CREB in vivo in the CNS. These results highlight a novel neutrophic property of cinnamon and its metabolite NaB via PKA - CREB pathway, which may be of benefit for various neurodegenerative disorders.
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583
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Nassireslami E, Nikbin P, Payandemehr B, Amini E, Mohammadi M, Vakilzadeh G, Ghadiri T, Noorbakhsh F, Sharifzadeh M. A cAMP analog reverses contextual and tone memory deficits induced by a PKA inhibitor in Pavlovian fear conditioning. Pharmacol Biochem Behav 2013; 105:177-82. [PMID: 23470331 DOI: 10.1016/j.pbb.2013.02.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 02/11/2013] [Accepted: 02/20/2013] [Indexed: 10/27/2022]
Abstract
Despite extensive investigations, molecular mechanisms underlying the formation of fear memory are not completely understood. We have previously investigated the role of protein kinase AII (PKAII) in spatial acquisition and memory retention using Morris water maze. In the current study, we have further analyzed the role of PKA in memory consolidation using a fear conditioning response model. Experiments were performed using intrahippocampal infusions of dibutyryl cyclic AMP (bucladesine), a cell permeable analog of cAMP and H89, as a selective PKAII inhibitor, in male rats. The animals were trained for one session which included 4 consecutive trials of tone-shock pairing on the training day. Fear to the context and tone was evaluated by measuring freezing behavior 24h and 48h after training respectively. Bilateral infusion of 100 and 300μM/side of bucladesine immediately after training increased freezing percentage in rats, which indicated an improvement in memory consolidation. Administration of 10μM/side (but not 5μM/side) of H-89 impaired contextual and cued fear conditioning significantly compared to the control animals. Moreover, administration of bucladesine (100 and 300μM/side), 5min after H-89 infusion (10μM/side) reversed the impairment of contextual and auditory-cued fear conditioning in rats and freezing percentage increased to those of control animals. Altogether, these results indicate that PKA inhibitor-induced memory deficit was attenuated by a cAMP analog and that the cAMP/PKA signaling pathway has an important role for memory consolidation in fear conditioning response model.
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Affiliation(s)
- Ehsan Nassireslami
- Department of Pharmacology and Toxicology, Pharmaceutical Sciences Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
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584
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In vivo quantitative proteomics of somatosensory cortical synapses shows which protein levels are modulated by sensory deprivation. Proc Natl Acad Sci U S A 2013; 110:E726-35. [PMID: 23382246 DOI: 10.1073/pnas.1300424110] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Postnatal bilateral whisker trimming was used as a model system to test how synaptic proteomes are altered in barrel cortex by sensory deprivation during synaptogenesis. Using quantitative mass spectrometry, we quantified more than 7,000 synaptic proteins and identified 89 significantly reduced and 161 significantly elevated proteins in sensory-deprived synapses, 22 of which were validated by immunoblotting. More than 95% of quantified proteins, including abundant synaptic proteins such as PSD-95 and gephyrin, exhibited no significant difference under high- and low-activity rearing conditions, suggesting no tissue-wide changes in excitatory or inhibitory synaptic density. In contrast, several proteins that promote mature spine morphology and synaptic strength, such as excitatory glutamate receptors and known accessory factors, were reduced significantly in deprived synapses. Immunohistochemistry revealed that the reduction in SynGAP1, a postsynaptic scaffolding protein, was restricted largely to layer I of barrel cortex in sensory-deprived rats. In addition, protein-degradation machinery such as proteasome subunits, E2 ligases, and E3 ligases, accumulated significantly in deprived synapses, suggesting targeted synaptic protein degradation under sensory deprivation. Importantly, this screen identified synaptic proteins whose levels were affected by sensory deprivation but whose synaptic roles have not yet been characterized in mammalian neurons. These data demonstrate the feasibility of defining synaptic proteomes under different sensory rearing conditions and could be applied to elucidate further molecular mechanisms of sensory development.
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585
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Dubnau J, Chiang AS. Systems memory consolidation in Drosophila. Curr Opin Neurobiol 2013; 23:84-91. [DOI: 10.1016/j.conb.2012.09.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 09/25/2012] [Indexed: 10/27/2022]
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586
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Learning-related synaptic growth mediated by internalization of Aplysia cell adhesion molecule is controlled by membrane phosphatidylinositol 4,5-bisphosphate synthetic pathway. J Neurosci 2013; 32:16296-305. [PMID: 23152613 DOI: 10.1523/jneurosci.1872-12.2012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Long-term facilitation in Aplysia is accompanied by the growth of new synaptic connections between the sensory and motor neurons of the gill-withdrawal reflex. One of the initial steps leading to the growth of these synapses is the internalization, induced by 5-HT, of the transmembrane isoform of Aplysia cell-adhesion molecule (TM-apCAM) from the plasma membrane of sensory neurons (Bailey et al., 1992). However, the mechanisms that govern the internalization of TM-apCAM and how this internalization is coupled to the molecular events that initiate the structural changes are not fully understood. Here, we report that the synthesis of membrane phosphatidylinositol 4,5-bisphosphate [PI(4,5)P(2)], which is known to be mediated by a signaling cascade through Aplysia Sec7 protein (ApSec7) and phosphatidylinositol-4-phosphate 5-kinase type I α (PIP5KIα) is required for both the internalization of TM-apCAM and the initiation of synaptic growth during 5-HT-induced long-term facilitation. Pharmacological blockade of PI(4,5)P(2) synthesis by the application of the inhibitor phenylarsine oxide blocked the internalization of apCAM. Furthermore, perturbation of the endogenous activation of ApSec7 and its downstream target PIP5KIα also blocked 5-HT-mediated internalization of TM-apCAM and synaptic growth. Finally, long-term facilitation was specifically impaired by blocking the ApSec7 signaling pathway at sensory-to-motor neuron synapses. These data indicate that the ApSec7/PIP5KIα signaling pathway is actively recruited during learning-related 5-HT signaling and acts as a key regulator of apCAM internalization associated with the formation of new synaptic connections during long-term facilitation.
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587
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Zhang G, Gao Z, Guan S, Zhu Y, Wang JH. Upregulation of excitatory neurons and downregulation of inhibitory neurons in barrel cortex are associated with loss of whisker inputs. Mol Brain 2013; 6:2. [PMID: 23286328 PMCID: PMC3548736 DOI: 10.1186/1756-6606-6-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 12/28/2012] [Indexed: 11/10/2022] Open
Abstract
Loss of a sensory input causes the hypersensitivity in other modalities. In addition to cross-modal plasticity, the sensory cortices without receiving inputs undergo the plastic changes. It is not clear how the different types of neurons and synapses in the sensory cortex coordinately change after input deficits in order to prevent loss of their functions and to be used for other modalities. We studied this subject in the barrel cortices from whiskers-trimmed mice vs. controls. After whisker trimming for a week, the intrinsic properties of pyramidal neurons and the transmission of excitatory synapses were upregulated in the barrel cortex, but inhibitory neurons and GABAergic synapses were downregulated. The morphological analyses indicated that the number of processes and spines in pyramidal neurons increased, whereas the processes of GABAergic neurons decreased in the barrel cortex. The upregulation of excitatory neurons and the downregulation of inhibitory neurons boost the activity of network neurons in the barrel cortex to be high levels, which prevent the loss of their functions and enhances their sensitivity to sensory inputs. These changes may prepare for attracting the innervations from sensory cortices and/or peripheral nerves for other modalities during cross-modal plasticity.
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Affiliation(s)
- Guanjun Zhang
- Department of Physiology, Bengbu Medical College, Bengbu, Anhui Province 233000, China
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588
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Otsuka E, Matsunaga M, Okada R, Yamagishi M, Okuta A, Lukowiak K, Ito E. Increase in cyclic AMP concentration in a cerebral giant interneuron mimics part of a memory trace for conditioned taste aversion of the pond snail. Biophysics (Nagoya-shi) 2013; 9:161-6. [PMID: 27493554 PMCID: PMC4629678 DOI: 10.2142/biophysics.9.161] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 10/18/2013] [Indexed: 12/02/2022] Open
Abstract
Conditioned taste aversion (CTA) can be classically conditioned in the pond snail Lymnaea stagnalis and subsequently be consolidated into long-term memory (LTM). The neural trace that subserves CTA-LTM can be summarized as follows: A polysynaptic inhibitory postsynaptic potential recorded in the neuron 1 medial (N1M) cell in the conditioned snails as a result of activation of the cerebral giant cell (CGC) is larger and lasts longer than that in control snails. The N1M cell is ultimately activated by the CGC via the neuron 3 tonic (N3t) cell. That is, the inhibitory monosynaptic inputs from the N3t cell to the N1M cell are facilitated. The N1M and N3t cells are the members of feeding central pattern generator, whereas the CGC is a multimodal interneuron thought to play a key role in feeding behavior. Here we examined the involvement of a second messenger, cAMP, in the establishment of the memory trace. We injected cAMP into the CGC and monitored the potentials of the B3 motor neuron activated by the CGC. B3 activity is used as an index for the synaptic inputs from the N3t cell to the N1M cell. We found that the B3 potentials were transiently enlarged. Thus, when the cAMP concentration is increased in the CGC by taste aversion training, cAMP-induced changes may play a key role in the establishment of a memory trace in the N3t cell.
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Affiliation(s)
- Emi Otsuka
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan
| | - Miho Matsunaga
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan
| | - Ryuichi Okada
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan
| | - Miki Yamagishi
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan
| | - Akiko Okuta
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Ken Lukowiak
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Etsuro Ito
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan
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589
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Kida S. A Functional Role for CREB as a Positive Regulator of Memory Formation and LTP. Exp Neurobiol 2012; 21:136-40. [PMID: 23319873 PMCID: PMC3538177 DOI: 10.5607/en.2012.21.4.136] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 10/30/2012] [Indexed: 11/19/2022] Open
Abstract
cAMP response element-binding protein (CREB), a transcription factor, has been shown to play a central role in memory formation, and its involvement in this process has been investigated using a wide range of animal models, from nematodes to higher animals. Various CREB mutant mice have been developed and investigated. Several types of mutant mice with loss of CREB function have impaired memory formation and long-term potentiation (LTP), suggesting that CREB plays essential roles in these processes. To characterize the roles of CREB in memory formation and LTP further, mutant mice displaying gain of CREB function have been generated and analyzed. Importantly, CREB-DIEDML mice and CREB-Y134F mice showed enhanced memory formation, whereas CREB-VP16 mice displayed a lowered threshold of long-lasting LTP (L-LTP) induction, strongly suggesting that CREB functions as a positive regulator of memory formation and LTP. In this review, I focus on the effects of the genetic activation of CREB in LTP and memory formation and summarize previous findings.
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Affiliation(s)
- Satoshi Kida
- Department of Bioscience, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo 156-8502, Japan. ; Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama 332-0012, Japan
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590
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Wang H, Zhuo M. Group I metabotropic glutamate receptor-mediated gene transcription and implications for synaptic plasticity and diseases. Front Pharmacol 2012; 3:189. [PMID: 23125836 PMCID: PMC3485740 DOI: 10.3389/fphar.2012.00189] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 10/11/2012] [Indexed: 12/05/2022] Open
Abstract
Stimulation of group I metabotropic glutamate receptors (mGluRs) initiates a wide variety of signaling pathways. Group I mGluR activation can regulate gene expression at both translational and transcriptional levels, and induces translation or transcription-dependent synaptic plastic changes in neurons. The group I mGluR-mediated translation-dependent neural plasticity has been well reviewed. In this review, we will highlight group I mGluR-induced gene transcription and its role in synaptic plasticity. The signaling pathways (PKA, CaMKs, and MAPKs) which have been shown to link group I mGluRs to gene transcription, the relevant transcription factors (CREB and NF-κB), and target proteins (FMRP and ARC) will be documented. The significance and future direction for characterizing group I mGluR-mediated gene transcription in fragile X syndrome, schizophrenia, drug addiction, and other neurological disorders will also be discussed.
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Affiliation(s)
- Hansen Wang
- Department of Physiology, Faculty of Medicine, University of Toronto Toronto, ON, Canada
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591
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Sakaguchi M, Hayashi Y. Catching the engram: strategies to examine the memory trace. Mol Brain 2012; 5:32. [PMID: 22999350 PMCID: PMC3462696 DOI: 10.1186/1756-6606-5-32] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 09/18/2012] [Indexed: 12/11/2022] Open
Abstract
Memories are stored within neuronal ensembles in the brain. Modern genetic techniques can be used to not only visualize specific neuronal ensembles that encode memories (e.g., fear, craving) but also to selectively manipulate those neurons. These techniques are now being expanded for the study of various types of memory. In this review, we will summarize the genetic methods used to visualize and manipulate neurons involved in the representation of memory engrams. The methods will help clarify how memory is encoded, stored and processed in the brain. Furthermore, these approaches may contribute to our understanding of the pathological mechanisms associated with human memory disorders and, ultimately, may aid the development of therapeutic strategies to ameliorate these diseases.
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Affiliation(s)
| | - Yasunori Hayashi
- Brain Science Institute, RIKEN, Wako, Saitama, 351-0198, Japan
- Saitama University Brain Science Institute, Saitama University, Saitama, 338-8570, Japan
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592
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Farah CA, Lindeman AA, Siu V, Gupta MD, Sossin WS. Autophosphorylation of the C2 domain inhibits translocation of the novel protein kinase C (nPKC) Apl II. J Neurochem 2012; 123:360-72. [PMID: 22913526 DOI: 10.1111/j.1471-4159.2012.07930.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 08/16/2012] [Accepted: 08/17/2012] [Indexed: 11/29/2022]
Abstract
Protein kinase Cs (PKCs) are critical signaling molecules controlled by complex regulatory pathways. Herein, we describe an important regulatory role for C2 domain phosphorylation. Novel PKCs (nPKCs) contain an N-terminal C2 domain that cannot bind to calcium. Previously, we described an autophosphorylation site in the Aplysia novel PKC Apl II that increased the binding of the C2 domain to lipids. In this study, we show that the function of this phosphorylation is to inhibit PKC translocation. Indeed, a phosphomimetic serine-glutamic acid mutation reduced translocation of PKC Apl II while blocking phosphorylation with a serine-alanine mutation enhanced translocation and led to the persistence of the kinase at the membrane longer after the end of the stimulation. Consistent with a role for autophosphorylation in regulating kinase translocation, inhibiting PKC activity using bisindolymaleimide 1 increased physiological translocation of PKC Apl II, whereas inhibiting phosphatase activity using calyculin A inhibited physiological translocation of PKC Apl II in neurons. Our results suggest a major role for autophosphorylation-dependent regulation of translocation.
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Affiliation(s)
- Carole A Farah
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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593
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A cellular model of memory reconsolidation involves reactivation-induced destabilization and restabilization at the sensorimotor synapse in Aplysia. Proc Natl Acad Sci U S A 2012; 109:14200-5. [PMID: 22893682 DOI: 10.1073/pnas.1211997109] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The memory reconsolidation hypothesis suggests that a memory trace becomes labile after retrieval and needs to be reconsolidated before it can be stabilized. However, it is unclear from earlier studies whether the same synapses involved in encoding the memory trace are those that are destabilized and restabilized after the synaptic reactivation that accompanies memory retrieval, or whether new and different synapses are recruited. To address this issue, we studied a simple nonassociative form of memory, long-term sensitization of the gill- and siphon-withdrawal reflex in Aplysia, and its cellular analog, long-term facilitation at the sensory-to-motor neuron synapse. We found that after memory retrieval, behavioral long-term sensitization in Aplysia becomes labile via ubiquitin/proteasome-dependent protein degradation and is reconsolidated by means of de novo protein synthesis. In parallel, we found that on the cellular level, long-term facilitation at the sensory-to-motor neuron synapse that mediates long-term sensitization is also destabilized by protein degradation and is restabilized by protein synthesis after synaptic reactivation, a procedure that parallels memory retrieval or retraining evident on the behavioral level. These results provide direct evidence that the same synapses that store the long-term memory trace encoded by changes in the strength of synaptic connections critical for sensitization are disrupted and reconstructed after signal retrieval.
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594
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Wang H, Morishita Y, Miura D, Naranjo JR, Kida S, Zhuo M. Roles of CREB in the regulation of FMRP by group I metabotropic glutamate receptors in cingulate cortex. Mol Brain 2012; 5:27. [PMID: 22867433 PMCID: PMC3478997 DOI: 10.1186/1756-6606-5-27] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 08/02/2012] [Indexed: 12/04/2022] Open
Abstract
Background Fragile X syndrome is caused by lack of fragile X mental retardation protein (FMRP) due to silencing of the FMR1 gene. The metabotropic glutamate receptors (mGluRs) in the central nervous system contribute to higher brain functions including learning/memory, mental disorders and persistent pain. The transcription factor cyclic AMP-responsive element binding protein (CREB) is involved in important neuronal functions, such as synaptic plasticity and neuronal survival. Our recent study has shown that stimulation of Group I mGluRs upregulated FMRP and activated CREB in anterior cingulate cortex (ACC), a key region for brain cognitive and executive functions, suggesting that activation of Group I mGluRs may upregulate FMRP through CREB signaling pathway. Results In this study, we demonstrate that CREB contributes to the regulation of FMRP by Group I mGluRs. In ACC neurons of adult mice overexpressing dominant active CREB mutant, the upregulation of FMRP by stimulating Group I mGluR is enhanced compared to wild-type mice. However, the regulation of FMRP by Group I mGluRs is not altered by overexpression of Ca2+-insensitive mutant form of downstream regulatory element antagonist modulator (DREAM), a transcriptional repressor involved in synaptic transmission and plasticity. Conclusion Our study has provided further evidence for CREB involvement in regulation of FMRP by Group I mGluRs in ACC neurons, and may help to elucidate the pathogenesis of fragile X syndrome.
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Affiliation(s)
- Hansen Wang
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada
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