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Borovok N, Nesher E, Levin Y, Reichenstein M, Pinhasov A, Michaelevski I. Dynamics of Hippocampal Protein Expression During Long-term Spatial Memory Formation. Mol Cell Proteomics 2015; 15:523-41. [PMID: 26598641 DOI: 10.1074/mcp.m115.051318] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Indexed: 01/08/2023] Open
Abstract
Spatial memory depends on the hippocampus, which is particularly vulnerable to aging. This vulnerability has implications for the impairment of navigation capacities in older people, who may show a marked drop in performance of spatial tasks with advancing age. Contemporary understanding of long-term memory formation relies on molecular mechanisms underlying long-term synaptic plasticity. With memory acquisition, activity-dependent changes occurring in synapses initiate multiple signal transduction pathways enhancing protein turnover. This enhancement facilitates de novo synthesis of plasticity related proteins, crucial factors for establishing persistent long-term synaptic plasticity and forming memory engrams. Extensive studies have been performed to elucidate molecular mechanisms of memory traces formation; however, the identity of plasticity related proteins is still evasive. In this study, we investigated protein turnover in mouse hippocampus during long-term spatial memory formation using the reference memory version of radial arm maze (RAM) paradigm. We identified 1592 proteins, which exhibited a complex picture of expression changes during spatial memory formation. Variable linear decomposition reduced significantly data dimensionality and enriched three principal factors responsible for variance of memory-related protein levels at (1) the initial phase of memory acquisition (165 proteins), (2) during the steep learning improvement (148 proteins), and (3) the final phase of the learning curve (123 proteins). Gene ontology and signaling pathways analysis revealed a clear correlation between memory improvement and learning phase-curbed expression profiles of proteins belonging to specific functional categories. We found differential enrichment of (1) neurotrophic factors signaling pathways, proteins regulating synaptic transmission, and actin microfilament during the first day of the learning curve; (2) transcription and translation machinery, protein trafficking, enhancement of metabolic activity, and Wnt signaling pathway during the steep phase of memory formation; and (3) cytoskeleton organization proteins. Taken together, this study clearly demonstrates dynamic assembly and disassembly of protein-protein interaction networks depending on the stage of memory formation engrams.
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Affiliation(s)
- Natalia Borovok
- From the ‡Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv 6997801, Israel
| | - Elimelech Nesher
- §Department of Molecular Biology, Ariel University, Ariel 4070000, Israel
| | - Yishai Levin
- ¶de Botton Institute for Protein Profiling, The Nancy & Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Michal Reichenstein
- From the ‡Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv 6997801, Israel
| | - Albert Pinhasov
- §Department of Molecular Biology, Ariel University, Ariel 4070000, Israel
| | - Izhak Michaelevski
- From the ‡Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv 6997801, Israel; ‖Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
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Farah CA, Naqib F, Weatherill DB, Pack CC, Sossin WS. Synapse formation changes the rules for desensitization of PKC translocation in Aplysia. Eur J Neurosci 2014; 41:328-40. [PMID: 25401305 DOI: 10.1111/ejn.12794] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 10/15/2014] [Accepted: 10/23/2014] [Indexed: 11/29/2022]
Abstract
Protein kinase Cs (PKCs) are activated by translocating from the cytoplasm to the membrane. We have previously shown that serotonin-mediated translocation of PKC to the plasma membrane in Aplysia sensory neurons was subject to desensitization, a decrease in the ability of serotonin to induce translocation after previous application of serotonin. In Aplysia, changes in the strength of the sensory-motor neuron synapse are important for behavioral sensitization and PKC regulates a number of important aspects of this form of synaptic plasticity. We have previously suggested that the desensitization of PKC translocation in Aplysia sensory neurons may partially explain the differences between spaced and massed training, as spaced applications of serotonin, a cellular analog of spaced training, cause greater desensitization of PKC translocation than one massed application of serotonin, a cellular analog of massed training. Our previous studies were performed in isolated sensory neurons. In the present study, we monitored translocation of fluorescently-tagged PKC to the plasma membrane in living sensory neurons that were co-cultured with motor neurons to allow for synapse formation. We show that desensitization now becomes similar during spaced and massed applications of serotonin. We had previously modeled the signaling pathways that govern desensitization in isolated sensory neurons. We now modify this mathematical model to account for the changes observed in desensitization dynamics following synapse formation. Our study shows that synapse formation leads to significant changes in the molecular signaling networks that underlie desensitization of PKC translocation.
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Affiliation(s)
- Carole A Farah
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec, H3A 2B4, Canada
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3
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Kadakkuzha BM, Liu XA, Narvaez M, Kaye A, Akhmedov K, Puthanveettil SV. Asymmetric localization of natural antisense RNA of neuropeptide sensorin in Aplysia sensory neurons during aging and activity. Front Genet 2014; 5:84. [PMID: 24795747 PMCID: PMC4001032 DOI: 10.3389/fgene.2014.00084] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Accepted: 03/29/2014] [Indexed: 11/21/2022] Open
Abstract
Despite the advances in our understanding of transcriptome, regulation and function of its non-coding components continue to be poorly understood. Here we searched for natural antisense transcript for sensorin (NAT-SRN), a neuropeptide expressed in the presynaptic sensory neurons of gill-withdrawal reflex of the marine snail Aplysia californica. Sensorin (SRN) has a key role in learning and long-term memory storage in Aplysia. We have now identified NAT-SRN in the central nervous system (CNS) and have confirmed its expression by northern blotting and fluorescent RNA in situ hybridization. Quantitative analysis of NAT-SRN in micro-dissected cell bodies and processes of sensory neurons suggest that NAT-SRN is present in the distal neuronal processes along with sense transcripts. Importantly, aging is associated with reduction in levels of NAT-SRN in sensory neuron processes. Furthermore, we find that forskolin, an activator of CREB signaling, differentially alters the distribution of SRN and NAT-SRN. These studies reveal novel insights into physiological regulation of natural antisense RNAs.
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Affiliation(s)
- Beena M Kadakkuzha
- Department of Neuroscience, The Scripps Research Institute Jupiter, FL, USA
| | - Xin-An Liu
- Department of Neuroscience, The Scripps Research Institute Jupiter, FL, USA
| | - Maria Narvaez
- Department of Neuroscience, The Scripps Research Institute Jupiter, FL, USA
| | - Alexandra Kaye
- Department of Neuroscience, The Scripps Research Institute Jupiter, FL, USA
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4
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Zhou J, Zheng X, Shen H. Targeting RNA-splicing for SMA treatment. Mol Cells 2012; 33:223-8. [PMID: 22382684 PMCID: PMC3887702 DOI: 10.1007/s10059-012-0005-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Revised: 02/15/2012] [Accepted: 02/15/2012] [Indexed: 10/28/2022] Open
Abstract
The central dogma of DNA-RNA-protein was established more than 40 years ago. However, important biological processes have been identified since the central dogma was developed. For example, methylation is important in the regulation of transcription. In contrast, proteins, are more complex due to modifications such as phosphorylation, glycosylation, ubiquitination, or cleavage. RNA is the mediator between DNA and protein, but it can also be modulated at several levels. Among the most profound discoveries of RNA regulation is RNA splicing. It has been estimated that 80% of pre-mRNA undergo alternative splicing, which exponentially increases biological information flow in cellular processes. However, an increased number of regulated steps inevitably accompanies an increased number of errors. Abnormal splicing is often found in cells, resulting in protein dysfunction that causes disease. Splicing of the survival motor neuron (SMN) gene has been extensively studied during the last two decades. Accumulating knowledge on SMN splicing has led to speculation and search for spinal muscular atrophy (SMA) treatment by stimulating the inclusion of exon 7 into SMN mRNA. This mini-review summaries the latest progress on SMN splicing research as a potential treatment for SMA disease.
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Affiliation(s)
| | - Xuexiu Zheng
- School of Life Science, Gwangju Institute of Science and Technology, Gwangju 500-712,
Korea
| | - Haihong Shen
- School of Life Science, Gwangju Institute of Science and Technology, Gwangju 500-712,
Korea
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5
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Reduced neurogenesis and pre-synaptic dysfunction in the olfactory bulb of a rat model of depression. Neuroscience 2011; 192:609-18. [DOI: 10.1016/j.neuroscience.2011.06.043] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 05/20/2011] [Accepted: 06/15/2011] [Indexed: 01/19/2023]
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6
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Jung H, Holt CE. Local translation of mRNAs in neural development. WILEY INTERDISCIPLINARY REVIEWS. RNA 2011; 2:153-65. [PMID: 21956974 PMCID: PMC3683645 DOI: 10.1002/wrna.53] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Growing axons encounter numerous developmental signals to which they must promptly respond in order to properly form complex neural circuitry. In the axons, these signals are often transduced into a local increase or decrease in protein levels. Contrary to the traditional view that the cell bodies are the exclusive source of axonal proteins, it is becoming increasingly clear not only that de novo protein synthesis takes place in axons, but also that it is required for the axons to respond to certain signals. Here we review the current knowledge of local mRNA translation in developing neurons with a special focus on protein synthesis occurring in axons and growth cones.
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Affiliation(s)
- Hosung Jung
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Christine E. Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
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7
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Mpari B, Sreng L, Manrique C, Mourre C. KCa2 channels transiently downregulated during spatial learning and memory in rats. Hippocampus 2010; 20:352-63. [PMID: 19437421 DOI: 10.1002/hipo.20622] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Small-conductance calcium-activated potassium channels (K(Ca)2) are essential components involved in the modulation of neuronal excitability, underlying learning and memory. Recent evidence suggests that K(Ca)2 channel activity reduces synaptic transmission in a postsynaptic NMDA receptor-dependent manner and is modulated by long-term potentiation. We used radioactive in situ hybridization and apamin binding to investigate the amount of K(Ca)2 subunit mRNA and K(Ca)2 proteins in brain structures involved in learning and memory at different stages of a radial-arm maze task in naive, pseudoconditioned, and conditioned rats. We observed significant differences in K(Ca)2.2 and K(Ca)2.3, but not K(Ca)2.1 mRNA levels, between conditioned and pseudoconditioned rats. K(Ca)2.2 levels were transiently reduced in the dorsal CA fields of the hippocampus, whereas K(Ca)2.3 mRNA levels were reduced in the dorsal and ventral CA fields of the hippocampus, entorhinal cortex, and basolateral amygdaloid nucleus in conditioned rats, during early stages of learning. Levels of apamin-binding sites displayed a similar pattern to K(Ca)2 mRNA levels during learning. Spatial learning performance was positively correlated with levels of apamin-binding sites and K(Ca)2.3 mRNA in the dorsal CA1 field and negatively correlated in the dorsal CA3 field. These findings suggest that K(Ca)2 channels are transiently downregulated in the early stages of learning and that regulation of K(Ca)2 channel levels is involved in the modification of neuronal substrates underlying new information acquisition.
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Affiliation(s)
- Bedel Mpari
- Laboratoire de Neurobiologie Intégrative et Adaptative, Neurobiologie des Processus Mnésiques, UMR 6149, Aix-Marseille Université, CNRS, Centre St Charles, 3 Place Victor Hugo, 13331 Marseille Cedex 03, France
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8
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Crispino M, Cefaliello C, Kaplan B, Giuditta A. Protein synthesis in nerve terminals and the glia-neuron unit. Results Probl Cell Differ 2010; 48:243-67. [PMID: 19554280 DOI: 10.1007/400_2009_9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The progressive philogenetic lengthening of axonal processes and the increase in complexity of terminal axonal arborizations markedly augmented the demands of the neuronal cytoplasmic mass on somatic gene expression. It is proposed that in an adaptive response to this challenge, novel gene expression functions developed in the axon compartment, consisting of axonal and presynaptic translation systems that rely on the delivery of transcripts synthesized in adjacent glial cells. Such intercellular mode of gene expression would allow more rapid plastic changes to occur in spatially restricted neuronal domains, down to the size of individual synapses. The cell body contribution to local gene expression in well-differentiated neurons remains to be defined. The history of this concept and the experimental evidence supporting its validity are critically discussed in this article. The merit of this perspective lies with the recognition that plasticity events represent a major occurrence in the brain, and that they largely occur at synaptic sites, including presynaptic endings.
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Affiliation(s)
- Marianna Crispino
- Department of Biological Sciences, University of Naples Federico II, Naples, Italy
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9
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Kaplan BB, Gioio AE, Hillefors M, Aschrafi A. Axonal protein synthesis and the regulation of local mitochondrial function. Results Probl Cell Differ 2009; 48:225-42. [PMID: 19343315 PMCID: PMC2786086 DOI: 10.1007/400_2009_1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Axons and presynaptic nerve terminals of both invertebrate and mammalian SCG neurons contain a heterogeneous population of nuclear-encoded mitochondrial mRNAs and a local cytosolic protein synthetic system. Nearly one quarter of the total protein synthesized in these structural/functional domains of the neuron is destined for mitochondria. Acute inhibition of axonal protein synthesis markedly reduces the functional activity of mitochondria. The blockade of axonal protein into mitochondria had similar effects on the organelle's functional activity. In addition to mitochondrial mRNAs, SCG axons contain approximately 200 different microRNAs (miRs), short, noncoding RNA molecules involved in the posttranscriptional regulation of gene expression. One of these miRs (miR-338) targets cytochrome c oxidase IV (COXIV) mRNA. This nuclear-encoded mRNA codes for a protein that plays a key role in the assembly of the mitochondrial enzyme complex IV and oxidative phosphorylation. Over-expression of miR-338 in the axon markedly decreases COXIV expression, mitochondrial functional activity, and the uptake of neurotransmitter into the axon. Conversely, the inhibition of endogeneous miR-338 levels in the axon significantly increased mitochondrial activity and norepinephrine uptake into the axon. The silencing of COXIV expression in the axon using short, inhibitory RNAs (siRNAs) yielded similar results, a finding that indicated that the effects of miR-338 on mitochondrial activity and axon function were mediated, at least in part, through local COXIV mRNA translation. Taken together, recent findings establish that proteins requisite for mitochondrial activity are synthesized locally in the axon and nerve terminal, and call attention to the intimacy of the relationship that has evolved between the distant cellular domains of the neuron and its energy generating systems.
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Affiliation(s)
- Barry B Kaplan
- Laboratory of Molecular Biology, National Institute of Mental Health, NIH, Bethesda, MD 20892-1381, USA.
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10
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Michel M, Kemenes I, Müller U, Kemenes G. Different phases of long-term memory require distinct temporal patterns of PKA activity after single-trial classical conditioning. Learn Mem 2008; 15:694-702. [PMID: 18772258 DOI: 10.1101/lm.1088408] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The cAMP-dependent protein kinase (PKA) is known to play a critical role in both transcription-independent short-term or intermediate-term memory and transcription-dependent long-term memory (LTM). Although distinct phases of LTM already have been demonstrated in some systems, it is not known whether these phases require distinct temporal patterns of learning-induced PKA activation. This question was addressed in a robust form of associative LTM that emerges within a matter of hours after single-trial food-reward classical conditioning in the pond snail Lymnaea stagnalis. After establishing the molecular and functional identity of the PKA catalytic subunit in the Lymnaea nervous system, we used a combination of PKA activity measurement and inhibition techniques to investigate its role in LTM in intact animals. PKA activity in ganglia involved in single-trial learning showed a short latency but prolonged increase after classical conditioning. However, while increased PKA activity immediately after training (0-10 min) was essential for an early phase of LTM (6 h), the late phase of LTM (24 h) required a prolonged increase in PKA activity. These observations indicate mechanistically different roles for PKA in recent and more remote phases of LTM, which may underpin different cellular and molecular mechanisms required for these phases.
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Affiliation(s)
- Maximilian Michel
- Department of Biology and Environmental Sciences, Sussex Centre for Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom
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11
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Sánchez-Carbente MDR, Desgroseillers L. Understanding the importance of mRNA transport in memory. PROGRESS IN BRAIN RESEARCH 2008; 169:41-58. [PMID: 18394467 DOI: 10.1016/s0079-6123(07)00003-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
RNA localization is an important mechanism to sort proteins to specific subcellular domains. In neurons, several mRNAs are localized in dendrites and their presence allows autonomous control of local translation in response to stimulation of specific synapses. Active constitutive and activity-induced mechanisms of mRNA transport have been described that represent critical steps in the establishment and maintenance of synaptic plasticity. In recent years, the molecular composition of different transporting units has been reported and the identification of proteins and mRNAs in these RNA granules contributes to our understanding of the key steps that regulate mRNA transport and translation. Although RNA granules are heterogeneous, several proteins are common to different RNA granule populations, suggesting that they play important roles in the formation of the granules and/or their regulation during transport and translation. About 1-4% of the neuron transcriptome is found in RNA granules and the characterization of bound mRNAs reveal that they encode proteins of the cytoskeleton, the translation machinery, vesicle trafficking, and/or proteins involved in synaptic plasticity. Non-coding RNAs and microRNAs are also found in dendrites and likely regulate RNA translation. These mechanisms of mRNA transport and local translation are critical for synaptic plasticity mediated by activity or experience and memory.
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12
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Lee JA, Lee SH, Lee C, Chang DJ, Lee Y, Kim H, Cheang YH, Ko HG, Lee YS, Jun H, Bartsch D, Kandel ER, Kaang BK. PKA-activated ApAF-ApC/EBP heterodimer is a key downstream effector of ApCREB and is necessary and sufficient for the consolidation of long-term facilitation. ACTA ACUST UNITED AC 2006; 174:827-38. [PMID: 16966424 PMCID: PMC2064337 DOI: 10.1083/jcb.200512066] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Long-term memory requires transcriptional regulation by a combination of positive and negative transcription factors. Aplysia activating factor (ApAF) is known to be a positive transcription factor that forms heterodimers with ApC/EBP and ApCREB2. How these heterodimers are regulated and how they participate in the consolidation of long-term facilitation (LTF) has not, however, been characterized. We found that the functional activation of ApAF required phosphorylation of ApAF by PKA on Ser-266. In addition, ApAF lowered the threshold of LTF by forming a heterodimer with ApCREB2. Moreover, once activated by PKA, the ApAF-ApC/EBP heterodimer transactivates enhancer response element-containing genes and can induce LTF in the absence of CRE- and CREB-mediated gene expression. Collectively, these results suggest that PKA-activated ApAF-ApC/EBP heterodimer is a core downstream effector of ApCREB in the consolidation of LTF.
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Affiliation(s)
- Jin-A Lee
- Institute of Molecular Biology and Genetics, RIO, Department of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 151-747, Korea
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13
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Lyles V, Zhao Y, Martin KC. Synapse formation and mRNA localization in cultured Aplysia neurons. Neuron 2006; 49:349-56. [PMID: 16446139 DOI: 10.1016/j.neuron.2005.12.029] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2005] [Revised: 10/26/2005] [Accepted: 12/27/2005] [Indexed: 10/25/2022]
Abstract
mRNA localization and regulated translation provide a means of spatially restricting gene expression within neurons during axon guidance and long-term synaptic plasticity. Here we show that synapse formation specifically alters the localization of the mRNA encoding sensorin, a peptide neurotransmitter with neurotrophin-like properties. In isolated Aplysia sensory neurons, which do not form chemical synapses, sensorin mRNA is diffusely distributed throughout distal neurites. Upon contact with a target motor neuron, sensorin mRNA rapidly concentrates at synapses. This redistribution only occurs in the presence of a target motor neuron and parallels the distribution of sensorin protein. Reduction of sensorin mRNA, but not protein, with dsRNA inhibits synapse formation. Our results indicate that synapse formation can alter mRNA localization within individual neurons. They further suggest that translation of a specific localized mRNA, encoding the neuropeptide sensorin, is required for synapse formation between sensory and motor neurons.
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MESH Headings
- Analysis of Variance
- Animals
- Aplysia/cytology
- Blotting, Western/methods
- Cells, Cultured
- Coculture Techniques/methods
- Dactinomycin/pharmacology
- Diagnostic Imaging/methods
- Electric Stimulation/methods
- Electrophysiologic Techniques, Cardiac/methods
- Excitatory Postsynaptic Potentials/physiology
- Gene Expression Regulation/physiology
- Green Fluorescent Proteins/metabolism
- Immunohistochemistry/methods
- In Situ Hybridization/methods
- Microinjections/methods
- Motor Neurons/metabolism
- Motor Neurons/physiology
- Neurites/drug effects
- Neurites/metabolism
- Neurons/cytology
- Neurons/drug effects
- Neurons/physiology
- Neurons/radiation effects
- Neurons, Afferent/classification
- Neurons, Afferent/cytology
- Neurons, Afferent/drug effects
- Neurons, Afferent/physiology
- Neurons, Afferent/radiation effects
- Neuropeptides/genetics
- Neuropeptides/metabolism
- Potassium Chloride/pharmacology
- Protein Synthesis Inhibitors/pharmacology
- RNA, Double-Stranded/pharmacology
- RNA, Messenger/metabolism
- Synapses/physiology
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Affiliation(s)
- Vlasta Lyles
- Interdepartmental Program in Neuroscience, University of California, Los Angeles, Los Angeles, California 90095, USA
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14
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Levine T, Rabouille C. Endoplasmic reticulum: one continuous network compartmentalized by extrinsic cues. Curr Opin Cell Biol 2005; 17:362-8. [PMID: 15975783 DOI: 10.1016/j.ceb.2005.06.005] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Accepted: 06/06/2005] [Indexed: 11/19/2022]
Abstract
The endoplasmic reticulum (ER) is an extensive three-dimensional network that stretches from the inner nuclear envelope to the cell cortex with a single, continuous membrane and a single, continuous lumen. Yet the ER contains specialized regions that carry out unique functions. The question that immediately arises is how the ER can be compartmentalized if it is continuous, and the answer to this is that cellular landmarks with unique sub-cellular distributions impose non-uniformity on the ER from outside, creating structural and functional sub-domains of the ER.
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Affiliation(s)
- Tim Levine
- Division of Cell Biology, Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
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15
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16
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Ormond J, Hislop J, Zhao Y, Webb N, Vaillaincourt F, Dyer JR, Ferraro G, Barker P, Martin KC, Sossin WS. ApTrkl, a Trk-like Receptor, Mediates Serotonin- Dependent ERK Activation and Long-Term Facilitation in Aplysia Sensory Neurons. Neuron 2004; 44:715-28. [PMID: 15541318 DOI: 10.1016/j.neuron.2004.11.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2004] [Revised: 07/12/2004] [Accepted: 10/06/2004] [Indexed: 10/25/2022]
Abstract
The Trk family of receptor tyrosine kinases plays a role in synaptic plasticity and in behavioral memory in mammals. Here, we report the discovery of a Trk-like receptor, ApTrkl, in Aplysia. We show that it is expressed in the sensory neurons, the locus for synaptic facilitation, which is a cellular model for memory formation. Serotonin, the facilitatory neurotransmitter, activates ApTrkl, which, in turn, leads to activation of ERK. Finally, inhibiting the activation of ApTrkl with the Trk inhibitor K252a or using dsRNA to inhibit ApTrkl blocks the serotonin-mediated activation of ERK in the cell body, as well as the cell-wide long-term facilitation induced by 5-HT application to the cell body. Thus, transactivation of the receptor tyrosine kinase ApTrkl by serotonin is an essential step in the biochemical events leading to long-term facilitation in Aplysia.
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Affiliation(s)
- Jake Ormond
- Montreal Neurological Institute, McGill University, 3801 University Avenue, Montreal, Quebec H3A-2B4, Canada
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17
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Gioio AE, Lavina ZS, Jurkovicova D, Zhang H, Eyman M, Giuditta A, Kaplan BB. Nerve terminals of squid photoreceptor neurons contain a heterogeneous population of mRNAs and translate a transfected reporter mRNA. Eur J Neurosci 2004; 20:865-72. [PMID: 15305855 DOI: 10.1111/j.1460-9568.2004.03538.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is now well established that the distal structural/functional domains of the neuron contain 2a diverse population of mRNAs that program the local synthesis of protein. However, there is still a paucity of information on the composition and function of these mRNA populations in the adult nervous system. To generate empirically, hypotheses regarding the function of the local protein synthetic system, we have compared the mRNAs present in the squid giant axon and its parental cell bodies using differential mRNA display as an unbiased screen. The results of this screen facilitated the identification of 31 mRNAs that encoded cytoskeletal proteins, translation factors, ribosomal proteins, molecular motors, metabolic enzymes, nuclear-encoded mitochondrial mRNAs, and a molecular chaperone. Results of cell fractionation and RT-PCR analyses established that several of these mRNAs were present in polysomes present in the presynaptic nerve terminal of photoreceptor neurons, indicating that these mRNAs were being actively translated. Findings derived from in vitro transfection studies established that these isolated nerve terminals had the ability to translate a heterologous reporter mRNA. Based upon these data, it is hypothesized that the local protein synthetic system plays an important role in the maintenance/remodelling of the cytoarchitecture of the axon and nerve terminal, maintenance of the axon transport and mRNA translation systems, as well as contributing to the viability and function of the local mitochondria.
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Affiliation(s)
- Anthony E Gioio
- Laboratory of Molecular Biology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
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18
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Kalinovsky A, Scheiffele P. Transcriptional control of synaptic differentiation by retrograde signals. Curr Opin Neurobiol 2004; 14:272-9. [PMID: 15194106 DOI: 10.1016/j.conb.2004.05.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Synaptic differentiation during development is a multi-step process, which requires reciprocal communication between pre- and postsynaptic cells. Cell surface interactions can induce the assembly of synaptic specializations but maintenance and growth of synapses depend on transcriptional regulation. Transcriptional responses associated with synaptic differentiation are observed in central and peripheral neurons and depend on retrograde signals coming from the target region. Although the identity of most of the retrograde signaling pathways remains to be identified, the TGFbeta family of growth factors have emerged as one crucial signal at the neuromuscular junction. Here, we discuss evidence for transcriptional control during synaptic differentiation and the signaling pathways mediating retrograde TGFbeta signaling.
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Affiliation(s)
- Anna Kalinovsky
- Columbia University, Department of Physiology and Cellular Biophysics, 630 West 168(th) Street, P&S 11-511, New York, New York 10032, USA
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Chen ZJ, Vulevic B, Ile KE, Soulika A, Davis W, Reiner PB, Connop BP, Nathwani P, Trojanowski JQ, Tew KD. Association of ABCA2 expression with determinants of Alzheimer's disease. FASEB J 2004; 18:1129-31. [PMID: 15155565 DOI: 10.1096/fj.03-1490fje] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
With the use of a novel method for detecting differential gene expression, alterations in functional gene clusters related to transport or oxidative stress response and beta-amyloid (Abeta) peptide metabolism were identified in a HEK293 cell line engineered to overexpress the human ATP binding cassette transporter ABCA2. These included fatty acid binding protein, phospholipid binding protein, phospholipid synthesis protein, transporter cofactors, seladin-1, Abeta precursor protein (APP), vimentin, and low-density lipoprotein receptor-related protein. ABCA2 was highly expressed in neuroblastoma cells and colocalized with Abeta and APP. Additionally, increased APP protein levels were detected within ABCA2/APP double-transfected cells, and increased Abeta was detected in the media of ABCA2-transfected cells relative to controls. The transporter was abundant in the temporal and frontal regions of both normal and Alzheimer's disease (AD) brain but was detected at lower concentrations in the parietal, occipital, and cerebellar regions. The ABCA2 transfected cell line expressed resistance to a free radical initiator, confirming involvement in protection against reactive oxygen species and suggesting a further possible link to AD.
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Affiliation(s)
- Zhijian J Chen
- Department of Pharmacology, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA
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Walters ET, Bodnarova M, Billy AJ, Dulin MF, Díaz-Ríos M, Miller MW, Moroz LL. Somatotopic organization and functional properties of mechanosensory neurons expressing sensorin-A mRNA inAplysia californica. J Comp Neurol 2004; 471:219-40. [PMID: 14986314 DOI: 10.1002/cne.20042] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A previous study reported that a peptide, sensorin-A, is expressed exclusively in mechanosensory neurons having somata in central ganglia of Aplysia. The present study utilized in situ hybridization, staining by nerve back-fill and soma injection, and electrophysiological methods to characterize the locations, numbers, and functions of sensorin-A-expressing neurons and to define the relationships between soma locations and the locations of peripheral axons and receptive fields. Approximately 1,000 cells express sensorin-A mRNA in young adult animals (10-30 g) and 1,200 cells in larger adults (100-300 g). All of the labeled somata are in the CNS, primarily in the abdominal LE, rLE, RE and RF, pleural VC, cerebral J and K, and buccal S clusters. Expression also occurs in a few sparsely distributed cells in most ganglia. Together, receptive fields of all these mechanosensory clusters cover the entire body surface. Each VC cluster forms a somatotopic map of the ipsilateral body, a "sensory aplunculus." Cells in the pleural and cerebral clusters have partially overlapping sensory fields and synaptic targets. Buccal S cells have receptive fields on the buccal mass and lips and display notable differences in electrophysiological properties from other sensorin-A-expressing neurons. Neurons in all of the clusters have relatively high mechanosensory thresholds, responding preferentially to threatening or noxious stimuli. Synaptic outputs to target cells having defensive functions support a nociceptive role, as does peripheral sensitization following noxious stimulation, although additional functions are likely in some clusters. Interesting questions arise from observations that mRNA for sensorin-A is present not only in the somata but also in synaptic regions, connectives, and peripheral fibers.
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Affiliation(s)
- Edgar T Walters
- Department of Integrative Biology and Pharmacology, University of Texas-Houston Medical School, Houston, Texas 77030, USA.
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Abstract
The cell body has classically been considered the exclusive source of axonal proteins. However, significant evidence has accumulated recently to support the view that protein synthesis can occur in axons themselves, remote from the cell body. Indeed, local translation in axons may be integral to aspects of synaptogenesis, long-term facilitation, and memory storage in invertebrate axons, and for growth cone navigation in response to environmental stimuli in developing vertebrate axons. Here we review the evidence supporting mRNA translation in axons and discuss the potential roles that local protein synthesis may play during development and subsequent neuronal function. We advance the view that local translation provides a rapid supply of nascent proteins in restricted axonal compartments that can potentially underlie long-term responses to transient stimuli.
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Affiliation(s)
- Michael Piper
- Department of Anatomy, University of Cambridge, Cambridge CB2 3DY, United Kingdom.
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Giustetto M, Hegde AN, Si K, Casadio A, Inokuchi K, Pei W, Kandel ER, Schwartz JH. Axonal transport of eukaryotic translation elongation factor 1alpha mRNA couples transcription in the nucleus to long-term facilitation at the synapse. Proc Natl Acad Sci U S A 2003; 100:13680-5. [PMID: 14578450 PMCID: PMC263873 DOI: 10.1073/pnas.1835674100] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Long-term synaptic plasticity requires both gene expression in the nucleus and local protein synthesis at synapses. The effector proteins that link molecular events in the cell body with local maintenance of synaptic strength are not known. We now show that treatment with serotonin (5-HT) that produces long-term facilitation induces the Aplysia eukaryotic translation elongation factor 1alpha (Ap-eEF1A) as a late gene that might serve this coupling function in sensory neurons. Although the translation factor is induced, it is not transported into axon processes when the stimulation with 5-HT was restricted to the cell body. In contrast, its mRNA is transported when 5-HT was applied to both cell body and synapses. Intracellular injection of antisense oligonucleotides or antibodies that block the induction and expression of Ap-eEF1A do not affect the initial expression of long-term facilitation but do block its maintenance beyond 24 h. The transport of eEF1A protein and its mRNA to nerve terminals suggests that the translation factor plays a role in the local protein synthesis that is essential for maintaining newly formed synapses.
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Affiliation(s)
- Maurizio Giustetto
- Center for Neurobiology and Behavior, College of Physicians and Surgeons, New York State Psychiatric Institute, and Howard Hughes Medical Institute, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA
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Liu K, Hu JY, Wang D, Schacher S. Protein synthesis at synapse versus cell body: enhanced but transient expression of long-term facilitation at isolated synapses. JOURNAL OF NEUROBIOLOGY 2003; 56:275-86. [PMID: 12884266 DOI: 10.1002/neu.10242] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Protein synthesis at synaptic terminals contributes to LTP in hippocampus and to the formation of new synaptic connections by sensory neurons (SNs) of Aplysia. Here we report that after removal of the SN cell body, isolated SN synapses of Aplysia in culture express protein-synthesis dependent long-term facilitation (LTF) produced by 5-HT that decays rapidly. Changes in expression of a SN-specific neuropeptide sensorin in isolated SN varicosities parallel the changes in synaptic efficacy. At 24 h after 5-HT the magnitude of LTF produced at isolated SN synapses was significantly greater than that produced when SN cell bodies were present. LTF was maintained at 48 h at connections with SN cell bodies, but not at isolated SN synapses. The increase in synaptic efficacy at isolated SN synapses at 24 h was blocked by the protein synthesis inhibitor anisomycin. LTF was accompanied by changes in expression of sensorin. The increase in sensorin level at isolated SN varicosities with 5-HT was blocked by anisomycin or was reversed 48 h after 5-HT treatment alone. The results suggest that, as is the case for initial synapse formation between SNs and L7, changes in protein synthesis at synaptic terminals may contribute directly to LTF of stable synapses. Changes in expression within the cell body provide additional contributions for long-term maintenance of the new level of synaptic efficacy that was initiated directly by local changes in protein synthesis at or near synaptic terminals.
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Affiliation(s)
- Ke Liu
- Center for Neurobiology and Behavior, Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute, 1051 Riverside Drive, New York, New York 10032, USA
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