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Romaus-Sanjurjo D, Saikia JM, Kim HJ, Tsai KM, Le GQ, Zheng B. Overexpressing eukaryotic elongation factor 1 alpha (eEF1A) proteins to promote corticospinal axon repair after injury. Cell Death Discov 2022; 8:390. [PMID: 36123349 PMCID: PMC9485247 DOI: 10.1038/s41420-022-01186-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 09/01/2022] [Accepted: 09/07/2022] [Indexed: 11/08/2022] Open
Abstract
Although protein synthesis is hypothesized to have a pivotal role in axonal repair after central nervous system (CNS) injury, the role of core components of the protein synthesis machinery has not been examined. Notably, some elongation factors possess non-canonical functions that may further impact axonal repair. Here, we examined whether overexpressing eukaryotic elongation factor 1 alpha (eEF1A) proteins enhances the collateral sprouting of corticospinal tract (CST) neurons after unilateral pyramidotomy, along with the underlying molecular mechanisms. We found that overexpressing eEF1A proteins in CST neurons increased the levels of pS6, an indicator for mTOR activity, but not pSTAT3 and pAKT levels, in neuronal somas. Strikingly, overexpressing eEF1A2 alone, but neither eEF1A1 alone nor both factors simultaneously, increased protein synthesis and actin rearrangement in CST neurons. While eEF1A1 overexpression only slightly enhanced CST sprouting after pyramidotomy, eEF1A2 overexpression substantially enhanced this sprouting. Surprisingly, co-overexpression of both eEF1A1 and eEF1A2 led to a sprouting phenotype similar to wild-type controls, suggesting an antagonistic effect of overexpressing both proteins. These data provide the first evidence that overexpressing a core component of the translation machinery, eEF1A2, enhances CST sprouting, likely by a combination of increased protein synthesis, mTOR signaling and actin cytoskeleton rearrangement.
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Affiliation(s)
- Daniel Romaus-Sanjurjo
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
- NeuroAging Group (NEURAL), Clinical Neurosciences Research Laboratories (LINCs), Health Research Institute of Santiago de Compostela (IDIS), 15706, Santiago de Compostela, Spain
| | - Junmi M Saikia
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
- Neurosciences Graduate Program, University of California San Diego, La Jolla, CA, 92093, USA
| | - Hugo J Kim
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Kristen M Tsai
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Geneva Q Le
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Binhai Zheng
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA.
- VA San Diego Research Service, San Diego, CA, 92161, USA.
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2
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Analysis of the Expression and Subcellular Distribution of eEF1A1 and eEF1A2 mRNAs during Neurodevelopment. Cells 2022; 11:cells11121877. [PMID: 35741005 PMCID: PMC9220863 DOI: 10.3390/cells11121877] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 05/30/2022] [Accepted: 05/31/2022] [Indexed: 12/04/2022] Open
Abstract
Neurodevelopment is accompanied by a precise change in the expression of the translation elongation factor 1A variants from eEF1A1 to eEF1A2. These are paralogue genes that encode 92% identical proteins in mammals. The switch in the expression of eEF1A variants has been well studied in mouse motor neurons, which solely express eEF1A2 by four weeks of postnatal development. However, changes in the subcellular localization of eEF1A variants during neurodevelopment have not been studied in detail in other neuronal types because antibodies lack perfect specificity, and immunofluorescence has a low sensitivity. In hippocampal neurons, eEF1A is related to synaptic plasticity and memory consolidation, and decreased eEF1A expression is observed in the hippocampus of Alzheimer's patients. However, the specific variant involved in these functions is unknown. To distinguish eEF1A1 from eEF1A2 expression, we have designed single-molecule fluorescence in-situ hybridization probes to detect either eEF1A1 or eEF1A2 mRNAs in cultured primary hippocampal neurons and brain tissues. We have developed a computational framework, ARLIN (analysis of RNA localization in neurons), to analyze and compare the subcellular distribution of eEF1A1 and eEF1A2 mRNAs at specific developmental stages and in mature neurons. We found that eEF1A1 and eEF1A2 mRNAs differ in expression and subcellular localization over neurodevelopment, and eEF1A1 mRNAs localize in dendrites and synapses during dendritogenesis and synaptogenesis. Interestingly, mature hippocampal neurons coexpress both variant mRNAs, and eEF1A1 remains the predominant variant in dendrites.
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3
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Mazaré N, Oudart M, Moulard J, Cheung G, Tortuyaux R, Mailly P, Mazaud D, Bemelmans AP, Boulay AC, Blugeon C, Jourdren L, Le Crom S, Rouach N, Cohen-Salmon M. Local Translation in Perisynaptic Astrocytic Processes Is Specific and Changes after Fear Conditioning. Cell Rep 2021; 32:108076. [PMID: 32846133 PMCID: PMC7450274 DOI: 10.1016/j.celrep.2020.108076] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 07/08/2020] [Accepted: 08/05/2020] [Indexed: 12/14/2022] Open
Abstract
Local translation is a conserved mechanism conferring cells the ability to quickly respond to local stimuli. In the brain, it has been recently reported in astrocytes, whose fine processes contact blood vessels and synapses. Yet the specificity and regulation of astrocyte local translation remain unknown. We study hippocampal perisynaptic astrocytic processes (PAPs) and show that they contain the machinery for translation. Using a refined immunoprecipitation technique, we characterize the entire pool of ribosome-bound mRNAs in PAPs and compare it with the one expressed in the whole astrocyte. We find that a specific pool of mRNAs is highly polarized at the synaptic interface. These transcripts encode an unexpected molecular repertoire, composed of proteins involved in iron homeostasis, translation, cell cycle, and cytoskeleton. Remarkably, we observe alterations in global RNA distribution and ribosome-bound status of some PAP-enriched transcripts after fear conditioning, indicating the role of astrocytic local translation in memory and learning. Local translation occurs in perisynaptic astrocytic processes (PAPs) The repertoire of ribosome-bound mRNAs enriched in hippocampal PAPs is specific RNA distribution and local translation change in PAPs after fear conditioning
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Affiliation(s)
- Noémie Mazaré
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France; Doctoral School No. 158, Pierre and Marie Curie University, 75005 Paris, France
| | - Marc Oudart
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France; Doctoral School No. 158, Pierre and Marie Curie University, 75005 Paris, France
| | - Julien Moulard
- Doctoral School No. 158, Pierre and Marie Curie University, 75005 Paris, France; Neuroglial Interactions in Cerebral Physiopathology Research Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - Giselle Cheung
- Neuroglial Interactions in Cerebral Physiopathology Research Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - Romain Tortuyaux
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - Philippe Mailly
- Orion Imaging Facility, Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - David Mazaud
- Neuroglial Interactions in Cerebral Physiopathology Research Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - Alexis-Pierre Bemelmans
- CEA, DRF, Institut de Biologie François Jacob, Molecular Imaging Research Center (MIRCen), 92265 Fontenay-aux-Roses, France; CNRS, CEA, Université Paris-Sud, Université Paris-Saclay, Neurodegenerative Diseases Laboratory (UMR9199), 92265 Fontenay-aux-Roses, France
| | - Anne-Cécile Boulay
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - Corinne Blugeon
- Genomic Facility, Institut de Biologie de l'ENS (IBENS), Département de Biologie, École Normale Supérieure, CNRS, INSERM, Université PSL, 75005 Paris, France
| | - Laurent Jourdren
- Genomic Facility, Institut de Biologie de l'ENS (IBENS), Département de Biologie, École Normale Supérieure, CNRS, INSERM, Université PSL, 75005 Paris, France
| | - Stéphane Le Crom
- Genomic Facility, Institut de Biologie de l'ENS (IBENS), Département de Biologie, École Normale Supérieure, CNRS, INSERM, Université PSL, 75005 Paris, France; Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratory of Computational and Quantitative Biology (LCQB), 75005 Paris, France
| | - Nathalie Rouach
- Neuroglial Interactions in Cerebral Physiopathology Research Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France
| | - Martine Cohen-Salmon
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, Paris, France.
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4
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Mazaré N, Oudart M, Cohen-Salmon M. Local translation in perisynaptic and perivascular astrocytic processes - a means to ensure astrocyte molecular and functional polarity? J Cell Sci 2021; 134:237323. [PMID: 33483366 DOI: 10.1242/jcs.251629] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Together with the compartmentalization of mRNAs in distal regions of the cytoplasm, local translation constitutes a prominent and evolutionarily conserved mechanism mediating cellular polarization and the regulation of protein delivery in space and time. The translational regulation of gene expression enables a rapid response to stimuli or to a change in the environment, since the use of pre-existing mRNAs can bypass time-consuming nuclear control mechanisms. In the brain, the translation of distally localized mRNAs has been mainly studied in neurons, whose cytoplasmic protrusions may be more than 1000 times longer than the diameter of the cell body. Importantly, alterations in local translation in neurons have been implicated in several neurological diseases. Astrocytes, the most abundant glial cells in the brain, are voluminous, highly ramified cells that project long processes to neurons and brain vessels, and dynamically regulate distal synaptic and vascular functions. Recent research has demonstrated the presence of local translation at these astrocytic interfaces that might regulate the functional compartmentalization of astrocytes. In this Review, we summarize our current knowledge about the localization and local translation of mRNAs in the distal perisynaptic and perivascular processes of astrocytes, and discuss their possible contribution to the molecular and functional polarity of astrocytes.
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Affiliation(s)
- Noémie Mazaré
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, F-75005 Paris, France.,École doctorale Cerveau Cognition Comportement 'ED3C' No. 158, Pierre and Marie Curie University, F-75005 Paris, France
| | - Marc Oudart
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, F-75005 Paris, France.,École doctorale Cerveau Cognition Comportement 'ED3C' No. 158, Pierre and Marie Curie University, F-75005 Paris, France
| | - Martine Cohen-Salmon
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS Unité Mixte de Recherche 724, INSERM Unité 1050, Labex Memolife, PSL Research University, F-75005 Paris, France .,École doctorale Cerveau Cognition Comportement 'ED3C' No. 158, Pierre and Marie Curie University, F-75005 Paris, France
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5
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Early defects in translation elongation factor 1α levels at excitatory synapses in α-synucleinopathy. Acta Neuropathol 2019; 138:971-986. [PMID: 31451907 DOI: 10.1007/s00401-019-02063-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 08/14/2019] [Accepted: 08/15/2019] [Indexed: 01/08/2023]
Abstract
Cognitive decline and dementia in neurodegenerative diseases are associated with synapse dysfunction and loss, which may precede neuron loss by several years. While misfolded and aggregated α-synuclein is recognized in the disease progression of synucleinopathies, the nature of glutamatergic synapse dysfunction and loss remains incompletely understood. Using fluorescence-activated synaptosome sorting (FASS), we enriched excitatory glutamatergic synaptosomes from mice overexpressing human alpha-synuclein (h-αS) and wild-type littermates to unprecedented purity. Subsequent label-free proteomic quantification revealed a set of proteins differentially expressed upon human alpha-synuclein overexpression. These include overrepresented proteins involved in the synaptic vesicle cycle, ER-Golgi trafficking, metabolism and cytoskeleton. Unexpectedly, we found and validated a steep reduction of eukaryotic translation elongation factor 1 alpha (eEF1A1) levels in excitatory synapses at early stages of h-αS mouse model pathology. While eEF1A1 reduction correlated with the loss of postsynapses, its immunoreactivity was found on both sides of excitatory synapses. Moreover, we observed a reduction in eEF1A1 immunoreactivity in the cingulate gyrus neuropil of patients with Lewy body disease along with a reduction in PSD95 levels. Altogether, our results suggest a link between structural impairments underlying cognitive decline in neurodegenerative disorders and local synaptic defects. eEF1A1 may therefore represent a limiting factor to synapse maintenance.
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6
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Hegde AN, Smith SG. Recent developments in transcriptional and translational regulation underlying long-term synaptic plasticity and memory. ACTA ACUST UNITED AC 2019; 26:307-317. [PMID: 31416904 PMCID: PMC6699410 DOI: 10.1101/lm.048769.118] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 06/20/2019] [Indexed: 12/16/2022]
Abstract
Formation of long-term synaptic plasticity that underlies long-term memory requires new protein synthesis. Years of research has elucidated some of the transcriptional and translational mechanisms that contribute to the production of new proteins. Early research on transcription focused on the transcription factor cAMP-responsive element binding protein. Since then, other transcription factors, such as the Nuclear Receptor 4 family of proteins that play a role in memory formation and maintenance have been identified. In addition, several studies have revealed details of epigenetic mechanisms consisting of new types of chemical alterations of DNA such as hydroxymethylation, and various histone modifications in long-term synaptic plasticity and memory. Our understanding of translational control critical for memory formation began with the identification of molecules that impinge on the 5′ and 3′ untranslated regions of mRNAs and continued with the appreciation for local translation near synaptic sites. Lately, a role for noncoding RNAs such as microRNAs in regulating translation factors and other molecules critical for memory has been found. This review describes the past research in brief and mainly focuses on the recent work on molecular mechanisms of transcriptional and translational regulation that form the underpinnings of long-term synaptic plasticity and memory.
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Affiliation(s)
- Ashok N Hegde
- Department of Biological and Environmental Sciences, Georgia College and State University, Milledgeville, Georgia 31061, USA
| | - Spencer G Smith
- Department of Biological and Environmental Sciences, Georgia College and State University, Milledgeville, Georgia 31061, USA
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7
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Sossin WS, Costa-Mattioli M. Translational Control in the Brain in Health and Disease. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a032912. [PMID: 30082469 DOI: 10.1101/cshperspect.a032912] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Translational control in neurons is crucially required for long-lasting changes in synaptic function and memory storage. The importance of protein synthesis control to brain processes is underscored by the large number of neurological disorders in which translation rates are perturbed, such as autism and neurodegenerative disorders. Here we review the general principles of neuronal translation, focusing on the particular relevance of several key regulators of nervous system translation, including eukaryotic initiation factor 2α (eIF2α), the mechanistic (or mammalian) target of rapamycin complex 1 (mTORC1), and the eukaryotic elongation factor 2 (eEF2). These pathways regulate the overall rate of protein synthesis in neurons and have selective effects on the translation of specific messenger RNAs (mRNAs). The importance of these general and specific translational control mechanisms is considered in the normal functioning of the nervous system, particularly during synaptic plasticity underlying memory, and in the context of neurological disorders.
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Affiliation(s)
- Wayne S Sossin
- Montreal Neurological Institute, McGill University, Montreal, Quebec H3A-2B4, Canada
| | - Mauro Costa-Mattioli
- Department of Neuroscience, Memory and Brain Research Center, Baylor College of Medicine, Houston, Texas 77030
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8
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Koley S, Rozenbaum M, Fainzilber M, Terenzio M. Translating regeneration: Local protein synthesis in the neuronal injury response. Neurosci Res 2019; 139:26-36. [DOI: 10.1016/j.neures.2018.10.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/13/2018] [Accepted: 10/02/2018] [Indexed: 12/21/2022]
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9
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McLachlan F, Sires AM, Abbott CM. The role of translation elongation factor eEF1 subunits in neurodevelopmental disorders. Hum Mutat 2018; 40:131-141. [PMID: 30370994 DOI: 10.1002/humu.23677] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 10/16/2018] [Accepted: 10/23/2018] [Indexed: 11/06/2022]
Abstract
The multi-subunit eEF1 complex plays a crucial role in de novo protein synthesis. The central functional component of the complex is eEF1A, which occurs as two independently encoded variants with reciprocal expression patterns: whilst eEF1A1 is widely expressed, eEF1A2 is found only in neurons and muscle. Heterozygous mutations in the gene encoding eEF1A2, EEF1A2, have recently been shown to cause epilepsy, autism, and intellectual disability. The remaining subunits of the eEF1 complex, eEF1Bα, eEF1Bδ, eEF1Bγ, and valyl-tRNA synthetase (VARS), together form the GTP exchange factor for eEF1A and are ubiquitously expressed, in keeping with their housekeeping role. However, mutations in the genes encoding these subunits EEF1B2 (eEF1Bα), EEF1D (eEF1Bδ), and VARS (valyl-tRNA synthetase) have also now been identified as causes of neurodevelopmental disorders. In this review, we describe the mutations identified so far in comparison with the degree of normal variation in each gene, and the predicted consequences of the mutations on the functions of the proteins and their isoforms. We discuss the likely effects of the mutations in the context of the role of protein synthesis in neuronal development.
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Affiliation(s)
- Fiona McLachlan
- Centre for Genomic and Experimental Medicine, Institute of Genetics and Molecular Medicine, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, UK
| | - Anna Martinez Sires
- Centre for Genomic and Experimental Medicine, Institute of Genetics and Molecular Medicine, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, UK
| | - Catherine M Abbott
- Centre for Genomic and Experimental Medicine, Institute of Genetics and Molecular Medicine, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, UK
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Beckelman BC, Day S, Zhou X, Donohue M, Gouras GK, Klann E, Keene CD, Ma T. Dysregulation of Elongation Factor 1A Expression is Correlated with Synaptic Plasticity Impairments in Alzheimer's Disease. J Alzheimers Dis 2018; 54:669-78. [PMID: 27567813 DOI: 10.3233/jad-160036] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Synaptic dysfunction may represent an early and crucial pathophysiology in Alzheimer's disease (AD). Recent studies implicate a connection between synaptic plasticity deficits and compromised capacity of de novo protein synthesis in AD. The mRNA translational factor eukaryotic elongation factor 1A (eEF1A) is critically involved in several forms of long-lasting synaptic plasticity. By examining postmortem human brain samples, a transgenic mouse model, and application of synthetic human Aβ42 on mouse hippocampal slices, we demonstrated that eEF1A protein levels were significantly decreased in AD, particularly in the hippocampus. In contrast, brain levels of eukaryotic elongation factor 2 were unaltered in AD. Further, upregulation of eEF1A expression by the adenylyl cyclase activator forskolin, which induces long-lasting synaptic plasticity, was blunted in hippocampal slices derived from Tg2576 AD model mice. Finally, Aβ-induced hippocampal long-term potentiation defects were alleviated by upregulation of eEF1A signaling via brain-specific knockdown of the gene encoding tuberous sclerosis 2. In summary, our findings suggest a strong correlation between the dysregulation of eEF1A synthesis and AD-associated synaptic failure. These findings provide insights into the understanding of molecular mechanisms underlying AD etiology and may aid in identification of novel biomarkers and therapeutic targets.
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Affiliation(s)
- Brenna C Beckelman
- Sticht Center on Aging, Department of Internal Medicine-Gerontology and Geriatric Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Stephen Day
- Sticht Center on Aging, Department of Internal Medicine-Gerontology and Geriatric Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Xueyan Zhou
- Sticht Center on Aging, Department of Internal Medicine-Gerontology and Geriatric Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Maggie Donohue
- Center for Neural Science, New York University, New York, NY, USA
| | - Gunnar K Gouras
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Eric Klann
- Center for Neural Science, New York University, New York, NY, USA
| | - C Dirk Keene
- Department of Pathology, University of Washington School of Medicine, Seattle, WA, USA
| | - Tao Ma
- Sticht Center on Aging, Department of Internal Medicine-Gerontology and Geriatric Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA.,Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA.,Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC, USA
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11
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Tréfier A, Pellissier LP, Musnier A, Reiter E, Guillou F, Crépieux P. G Protein-Coupled Receptors As Regulators of Localized Translation: The Forgotten Pathway? Front Endocrinol (Lausanne) 2018; 9:17. [PMID: 29456523 PMCID: PMC5801404 DOI: 10.3389/fendo.2018.00017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 01/15/2018] [Indexed: 12/31/2022] Open
Abstract
G protein-coupled receptors (GPCRs) exert their physiological function by transducing a complex signaling network that coordinates gene expression and dictates the phenotype of highly differentiated cells. Much is known about the gene networks they transcriptionally regulate upon ligand exposure in a process that takes hours before a new protein is synthesized. However, far less is known about GPCR impact on the translational machinery and subsequent mRNA translation, although this gene regulation level alters the cell phenotype in a strikingly different timescale. In fact, mRNA translation is an early response kinetically connected to signaling events, hence it leads to the synthesis of a new protein within minutes following receptor activation. By these means, mRNA translation is responsive to subtle variations of the extracellular environment. In addition, when restricted to cell subcellular compartments, local mRNA translation contributes to cell micro-specialization, as observed in synaptic plasticity or in cell migration. The mechanisms that control where in the cell an mRNA is translated are starting to be deciphered. But how an extracellular signal triggers such local translation still deserves extensive investigations. With the advent of high-throughput data acquisition, it now becomes possible to review the current knowledge on the translatome that some GPCRs regulate, and how this information can be used to explore GPCR-controlled local translation of mRNAs.
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Affiliation(s)
- Aurélie Tréfier
- Biologie et Bioinformatique des Systèmes de Signalisation, INRA, UMR85, Physiologie de la Reproduction et des Comportements, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais, Tours, France
- IFCE, Nouzilly, France
| | - Lucie P. Pellissier
- Déficit de Récompense, GPCR et sociabilité, INRA, UMR85, Physiologie de la Reproduction et des Comportements, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais, Tours, France
- IFCE, Nouzilly, France
| | - Astrid Musnier
- Biologie et Bioinformatique des Systèmes de Signalisation, INRA, UMR85, Physiologie de la Reproduction et des Comportements, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais, Tours, France
- IFCE, Nouzilly, France
| | - Eric Reiter
- Biologie et Bioinformatique des Systèmes de Signalisation, INRA, UMR85, Physiologie de la Reproduction et des Comportements, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais, Tours, France
- IFCE, Nouzilly, France
| | - Florian Guillou
- Plasticité Génomique et Expression Phénotypique, INRA, UMR85, Physiologie de la Reproduction et des Comportements, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais, Tours, France
- IFCE, Nouzilly, France
| | - Pascale Crépieux
- Biologie et Bioinformatique des Systèmes de Signalisation, INRA, UMR85, Physiologie de la Reproduction et des Comportements, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais, Tours, France
- IFCE, Nouzilly, France
- *Correspondence: Pascale Crépieux,
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Lu F, Shao G, Wang Y, Guan S, Burlingame AL, Liu X, Liang X, Knox R, Ferriero DM, Jiang X. Hypoxia-ischemia modifies postsynaptic GluN2B-containing NMDA receptor complexes in the neonatal mouse brain. Exp Neurol 2017; 299:65-74. [PMID: 28993251 DOI: 10.1016/j.expneurol.2017.10.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 09/09/2017] [Accepted: 10/05/2017] [Indexed: 01/08/2023]
Abstract
The N-methyl-d-aspartate-type glutamate receptor (NMDAR)-associated multiprotein complexes are indispensable for synaptic plasticity and cognitive functions. While purification and proteomic analyses of these signaling complexes have been performed in adult rodent and human brain, much less is known about the protein composition of NMDAR complexes in the developing brain and their modifications by neonatal hypoxic-ischemic (HI) brain injury. In this study, the postsynaptic density proteins were prepared from postnatal day 9 naïve, sham-operated and HI-injured mouse cortex. The GluN2B-containing NMDAR complexes were purified by immunoprecipitation with a mouse GluN2B antibody and subjected to mass spectrometry analysis for determination of the GluN2B binding partners. A total of 71 proteins of different functional categories were identified from the naïve animals as native GluN2B-interacting partners in the developing mouse brain. Neonatal HI reshaped the postsynaptic GluN2B interactome by recruiting new proteins, including multiple kinases, into the complexes; and modifying the existing associations within 1h of reperfusion. The early responses of postsynaptic NMDAR complexes and their related signaling networks may contribute to molecular processes leading to cell survival or death, brain damage and/or neurological disorders in term infants with neonatal encephalopathy.
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Affiliation(s)
- Fuxin Lu
- Department of Pediatrics, University of California San Francisco, CA, USA
| | - Guo Shao
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine, Baotou Medical College, Baotou, China
| | - Yongqiang Wang
- Department of Cellular & Molecular Pharmacology, University of California San Francisco, CA, USA; Howard Hughes Medical Institute, University of California, San Francisco, CA, USA
| | - Shenheng Guan
- Department of Pharmaceutical Chemistry, University of California San Francisco, CA, USA
| | - Alma L Burlingame
- Department of Pharmaceutical Chemistry, University of California San Francisco, CA, USA
| | - Xuemei Liu
- Central Laboratory, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Xiao Liang
- Central Laboratory, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Renatta Knox
- Department of Pediatrics, Weill Cornell Medical College, New York, NY, USA
| | - Donna M Ferriero
- Department of Pediatrics, University of California San Francisco, CA, USA; Department of Neurology, University of California San Francisco, CA, USA
| | - Xiangning Jiang
- Department of Pediatrics, University of California San Francisco, CA, USA.
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13
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Expression of Rac1 alternative 3′ UTRs is a cell specific mechanism with a function in dendrite outgrowth in cortical neurons. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1860:685-694. [DOI: 10.1016/j.bbagrm.2017.03.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 03/02/2017] [Accepted: 03/03/2017] [Indexed: 01/24/2023]
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14
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Beckelman BC, Zhou X, Keene CD, Ma T. Impaired Eukaryotic Elongation Factor 1A Expression in Alzheimer's Disease. NEURODEGENER DIS 2015; 16:39-43. [PMID: 26551858 DOI: 10.1159/000438925] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 07/23/2015] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND/AIMS Recent studies have indicated a link between the impaired capacity of de novo protein synthesis and neurodegenerative diseases including Alzheimer's disease (AD). Moreover, it has been established that eukaryotic elongation factor 1A (eEF1A) plays a critical role in maintaining long-term synaptic plasticity, a cellular model for learning and memory. The aim of the present study is to determine whether brain eEF1A protein levels are dysregulated in brain tissue from AD patients compared with controls. METHODS Postmortem human brain samples collected from patients clinically diagnosed as AD, and from age-matched healthy controls, were utilized for this study. Both Western blot and immunohistochemistry approaches were utilized to investigate the potential alteration of eEF1A protein levels by using a specific antibody. RESULTS Our data demonstrate that eEF1A expression is reduced in AD patients in the hippocampus, but not in the cerebellum or midfrontal gyrus. Furthermore, immunohistochemical experiments reveal that neuronal eEF1A reduction in the AD hippocampus is localized to the CA1 and dentate gyrus, but not to the CA3. CONCLUSION Dysregulation of eEF1A and its associated signaling pathways might represent novel molecular mechanisms underlying AD pathogenesis. Further investigation is necessary to determine whether eEF1A is a viable therapeutic target for AD and other cognitive syndromes.
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Affiliation(s)
- Brenna C Beckelman
- Departments of Internal Medicine-Gerontology and Geriatric Medicine, Wake Forest University School of Medicine, Winston-Salem, N.C., USA
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15
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Nandagopal N, Roux PP. Regulation of global and specific mRNA translation by the mTOR signaling pathway. ACTA ACUST UNITED AC 2015; 3:e983402. [PMID: 26779414 DOI: 10.4161/21690731.2014.983402] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 08/22/2014] [Accepted: 10/29/2014] [Indexed: 11/19/2022]
Abstract
The translation of mRNA into polypeptides is a key step in eukaryotic gene expression. Translation is mostly controlled at the level of initiation, which is partly regulated by the mammalian/mechanistic target of rapamycin (mTOR) signaling pathway. Whereas mTOR controls global protein synthesis through specific effector proteins, its role in the translation of select groups of mRNAs, such as those harboring a terminal oligopyrimidine (TOP) tract at their 5' end, remains more enigmatic. In this article, we describe the current knowledge on the role of mTOR in global mRNA translation, but also focus on the potential molecular mechanisms underlying the regulation of specific translational programs.
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Affiliation(s)
- Neethi Nandagopal
- Institute for Research in Immunology and Cancer (IRIC); Université de Montréal ; Montréal, Québec, Canada
| | - Philippe P Roux
- Institute for Research in Immunology and Cancer (IRIC); Université de Montréal; Montréal, Québec, Canada; Department of Pathology and Cell Biology; Faculty of Medicine; Université de Montréal; Montréal, Québec, Canada
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16
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Kim S, Martin KC. Neuron-wide RNA transport combines with netrin-mediated local translation to spatially regulate the synaptic proteome. eLife 2015; 4. [PMID: 25569157 PMCID: PMC4337609 DOI: 10.7554/elife.04158] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 01/08/2015] [Indexed: 11/13/2022] Open
Abstract
The persistence of experience-dependent changes in brain connectivity requires RNA localization and protein synthesis. Previous studies have demonstrated a role for local translation in altering the structure and function of synapses during synapse formation and experience-dependent synaptic plasticity. In this study, we ask whether in addition to promoting local translation, local stimulation also triggers directed trafficking of RNAs from nucleus to stimulated synapses. Imaging of RNA localization and translation in cultured Aplysia sensory-motor neurons revealed that RNAs were delivered throughout the arbor of the sensory neuron, but that translation was enriched only at sites of synaptic contact and/or synaptic stimulation. Investigation of the mechanisms that trigger local translation revealed a role for calcium-dependent retrograde netrin-1/DCC receptor signaling. Spatially restricting gene expression by regulating local translation rather than by directing the delivery of mRNAs from nucleus to stimulated synapses maximizes the readiness of the entire neuronal arbor to respond to local cues.
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Affiliation(s)
- Sangmok Kim
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, United States
| | - Kelsey C Martin
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, United States
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17
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Huntingtin is critical both pre- and postsynaptically for long-term learning-related synaptic plasticity in Aplysia. PLoS One 2014; 9:e103004. [PMID: 25054562 PMCID: PMC4108396 DOI: 10.1371/journal.pone.0103004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Accepted: 06/26/2014] [Indexed: 11/20/2022] Open
Abstract
Patients with Huntington’s disease exhibit memory and cognitive deficits many years before manifesting motor disturbances. Similarly, several studies have shown that deficits in long-term synaptic plasticity, a cellular basis of memory formation and storage, occur well before motor disturbances in the hippocampus of the transgenic mouse models of Huntington’s disease. The autosomal dominant inheritance pattern of Huntington’s disease suggests the importance of the mutant protein, huntingtin, in pathogenesis of Huntington’s disease, but wild type huntingtin also has been shown to be important for neuronal functions such as axonal transport. Yet, the role of wild type huntingtin in long-term synaptic plasticity has not been investigated in detail. We identified a huntingtin homolog in the marine snail Aplysia, and find that similar to the expression pattern in mammalian brain, huntingtin is widely expressed in neurons and glial cells. Importantly the expression of mRNAs of huntingtin is upregulated by repeated applications of serotonin, a modulatory transmitter released during learning in Aplysia. Furthermore, we find that huntingtin expression levels are critical, not only in presynaptic sensory neurons, but also in the postsynaptic motor neurons for serotonin-induced long-term facilitation at the sensory-to-motor neuron synapse of the Aplysia gill-withdrawal reflex. These results suggest a key role for huntingtin in long-term memory storage.
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18
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Abstract
Several studies have shown that synthesis of new proteins at the synapse is a prerequisite for the storage of long-term memories. Relatively little is known about the availability of distinct mRNA populations for translation at specific synapses, the process that determines mRNA localization, and the temporal designations of localized mRNA translation during memory storage. Techniques such as synaptosome preparation and microdissection of distal neuronal processes of cultured neurons and dendritic layers in brain slices are general approaches used to identify localized RNAs. Exploration of the association of RNA-binding proteins to the axonal transport machinery has led to the development of a strategy to identify RNAs that are transported from the cell body to synapses by molecular motor kinesin. In this article, RNA localization at the synapse, as well as its mechanisms and significance in understanding long-term memory storage, are discussed.
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19
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Shigeoka T, Lu B, Holt CE. Cell biology in neuroscience: RNA-based mechanisms underlying axon guidance. ACTA ACUST UNITED AC 2013; 202:991-9. [PMID: 24081488 PMCID: PMC3787380 DOI: 10.1083/jcb.201305139] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Axon guidance plays a key role in establishing neuronal circuitry. The motile tips of growing axons, the growth cones, navigate by responding directionally to guidance cues that pattern the embryonic neural pathways via receptor-mediated signaling. Evidence in vitro in the last decade supports the notion that RNA-based mechanisms contribute to cue-directed steering during axon guidance. Different cues trigger translation of distinct subsets of mRNAs and localized translation provides precise spatiotemporal control over the growth cone proteome in response to localized receptor activation. Recent evidence has now demonstrated a role for localized translational control in axon guidance decisions in vivo.
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Affiliation(s)
- Toshiaki Shigeoka
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, England, UK
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20
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Abstract
Here we describe a strategy designed to identify RNAs that are actively transported to synapses during learning. Our approach is based on the characterization of RNA transport complexes carried by molecular motor kinesin. Using this strategy in Aplysia, we have identified 5,657 unique sequences consisting of both coding and noncoding RNAs from the CNS. Several of these RNAs have key roles in the maintenance of synaptic function and growth. One of these RNAs, myosin heavy chain, is critical in presynaptic sensory neurons for the establishment of long-term facilitation, but not for its persistence.
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21
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Spontaneous transmitter release recruits postsynaptic mechanisms of long-term and intermediate-term facilitation in Aplysia. Proc Natl Acad Sci U S A 2012; 109:9137-42. [PMID: 22619333 DOI: 10.1073/pnas.1206846109] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Whereas short-term (minutes) facilitation at Aplysia sensory-motor neuron synapses is presynaptic, long-term (days) facilitation involves synaptic growth, which requires both presynaptic and postsynaptic mechanisms. How are the postsynaptic mechanisms recruited, and when does that process begin? We have been investigating the possible role of spontaneous transmitter release from the presynaptic neuron. In the previous paper, we found that spontaneous release is critical for the induction of long-term facilitation, and this process begins during an intermediate-term stage of facilitation that is the first stage to involve postsynaptic as well as presynaptic mechanisms. We now report that increased spontaneous release during the short-term stage acts as an orthograde signal to recruit postsynaptic mechanisms of intermediate-term facilitation including increased IP3, Ca(2+), and membrane insertion and recruitment of clusters of AMPA-like receptors, which may be first steps in synaptic growth during long-term facilitation. These results suggest that the different stages of facilitation involve a cascade of pre- and postsynaptic mechanisms, which is initiated by spontaneous release and may culminate in synaptic growth.
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22
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Jung H, Yoon BC, Holt CE. Axonal mRNA localization and local protein synthesis in nervous system assembly, maintenance and repair. Nat Rev Neurosci 2012; 13:308-24. [PMID: 22498899 PMCID: PMC3682205 DOI: 10.1038/nrn3210] [Citation(s) in RCA: 337] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
mRNAs can be targeted to specific neuronal subcellular domains, which enables rapid changes in the local proteome through local translation. This mRNA-based mechanism links extrinsic signals to spatially restricted cellular responses and can mediate stimulus-driven adaptive responses such as dendritic plasticity. Local mRNA translation also occurs in growing axons where it can mediate directional responses to guidance signals. Recent profiling studies have revealed that both growing and mature axons possess surprisingly complex and dynamic transcriptomes, thereby suggesting that axonal mRNA localization is highly regulated and has a role in a broad range of processes, a view that is increasingly being supported by new experimental evidence. Here, we review current knowledge on the roles and regulatory mechanisms of axonal mRNA translation and discuss emerging links to axon guidance, survival, regeneration and neurological disorders.
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Affiliation(s)
- Hosung Jung
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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23
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Upadhya SC, Smith TK, Brennan PA, Mychaleckyj JC, Hegde AN. Expression profiling reveals differential gene induction underlying specific and non-specific memory for pheromones in mice. Neurochem Int 2011; 59:787-803. [PMID: 21884744 DOI: 10.1016/j.neuint.2011.08.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 07/11/2011] [Accepted: 08/08/2011] [Indexed: 01/06/2023]
Abstract
Memory for the mating male's pheromones in female mice is thought to require synaptic changes in the accessory olfactory bulb (AOB). Induction of this memory depends on release of glutamate in response to pheromonal exposure coincident with release of norepinephrine (NE) in the AOB following mating. A similar memory for pheromones can also be induced artificially by local infusion of the GABA(A) receptor antagonist bicuculline into the AOB. The natural memory formed by exposure to pheromones during mating is specific to the pheromones sensed by the female during mating. In contrast, the artificial memory induced by bicuculline is non-specific and results in the female mice recognizing all pheromones as if they were from the mating male. Although protein synthesis has been shown to be essential for development of pheromone memory, the gene expression cascades critical for memory formation are not known. We investigated changes in gene expression in the AOB using oligonucleotide microarrays during mating-induced pheromone memory (MIPM) as well as bicuculline-induced pheromone memory (BIPM). We found the set of genes induced during MIPM and BIPM are largely non-overlapping and Ingenuity Pathway Analysis revealed that the signaling pathways in MIPM and BIPM also differ. The products of genes induced during MIPM are associated with synaptic function, indicating the possibility of modification at specific synapses, while those induced during BIPM appear to possess neuron-wide functions, which would be consistent with global cellular changes. Thus, these results begin to provide a mechanistic explanation for specific and non-specific memories induced by pheromones and bicuculline infusion respectively.
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Affiliation(s)
- Sudarshan C Upadhya
- Department of Neurobiology and Anatomy, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA
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24
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Redondo RL, Morris RGM. Making memories last: the synaptic tagging and capture hypothesis. Nat Rev Neurosci 2011; 12:17-30. [PMID: 21170072 DOI: 10.1038/nrn2963] [Citation(s) in RCA: 496] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The synaptic tagging and capture hypothesis of protein synthesis-dependent long-term potentiation asserts that the induction of synaptic potentiation creates only the potential for a lasting change in synaptic efficacy, but not the commitment to such a change. Other neural activity, before or after induction, can also determine whether persistent change occurs. Recent findings, leading us to revise the original hypothesis, indicate that the induction of a local, synapse-specific 'tagged' state and the expression of long-term potentiation are dissociable. Additional observations suggest that there are major differences in the mechanisms of functional and structural plasticity. These advances call for a revised theory that incorporates the specific molecular and structural processes involved. Addressing the physiological relevance of previous in vitro findings, new behavioural studies have experimentally translated the hypothesis to learning and the consolidation of newly formed memories.
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Affiliation(s)
- Roger L Redondo
- Laboratory for Cognitive Neuroscience, Centre for Cognitive and Neural Systems, The University of Edinburgh, 1 George Square, Edinburgh EH8 9JZ, UK
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25
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Molecular Mechanisms for the Initiation and Maintenance of Long-Term Memory Storage. RESEARCH AND PERSPECTIVES IN ALZHEIMER'S DISEASE 2011. [DOI: 10.1007/978-3-642-16602-0_13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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26
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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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27
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Translation of 5' terminal oligopyrimidine tract (5'TOP) mRNAs in Aplysia Californica is regulated by the target of rapamycin (TOR). Biochem Biophys Res Commun 2010; 404:816-21. [PMID: 21172307 DOI: 10.1016/j.bbrc.2010.12.066] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 12/13/2010] [Indexed: 11/21/2022]
Abstract
Aplysia californica is a model organism for determining the molecular basis of memory. In this system identified synaptic changes have been closely linked to behavioral memories. Long-term sensitization and long-term synaptic changes between sensory neurons and motor neurons require both gene expression followed by translational control of the newly expressed mRNAs. One important mechanism for translational control is mediated through the target of rapamycin (TOR) and one mechanism downstream of TOR is the translational control of mRNAs containing a 5' terminal oligopyrimidine tract (5'TOP) sequence in their mRNA transcript. These include all ribosomal proteins, elongation factors and a few other translational regulators. TOR regulation of 5'TOP mRNAs in vertebrates is thought to be due to TOR dependent removal of the translational repression mediated by the 5'TOP sequence. Here, we show that this mechanism is similar in Aplysia, whereby Aplysia 5'TOP mRNAs are repressed under basal conditions and this repression is removed by serotonin in a rapamycin-sensitive manner.
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28
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Ransdell JL, Faust TB, Schulz DJ. Correlated Levels of mRNA and Soma Size in Single Identified Neurons: Evidence for Compartment-specific Regulation of Gene Expression. Front Mol Neurosci 2010; 3:116. [PMID: 21119779 PMCID: PMC2991126 DOI: 10.3389/fnmol.2010.00116] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 10/09/2010] [Indexed: 11/13/2022] Open
Abstract
In addition to the overall complexity of transcriptional regulation, cells also must take into account the subcellular distribution of these gene products. This is particularly challenging for morphologically complex cells such as neurons. Yet the interaction between cellular morphology and gene expression is poorly understood. Here we provide some of the first evidence for a relationship between neuronal compartment size and maintenance of mRNA levels in neurons. We find that single-cell transcript levels of 18S rRNA, GAPDH, and EF1-alpha, all gene products with primary functions in the cell soma, are strongly correlated to soma size in multiple distinct neuronal types. Levels of mRNA for the K+ channel shal, which is localized exclusively to the soma, are negatively correlated with soma size, suggesting that gene expression does not simply track positively with compartment size. Conversely, levels of beta-actin and beta-tubulin mRNA, which are major cytoskeletal proteins of neuronal processes, do not correlate with soma size, but are strongly correlated with one another. Additionally, actin/tubulin expression levels correlate with voltage-gated ion channels that are uniquely localized to axons. These results suggest that steady-state transcript levels are differentially regulated based on the subcellular compartment within which a given gene product primarily acts.
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Affiliation(s)
- Joseph L Ransdell
- Department of Biological Sciences, University of Missouri Columbia Columbia, MO, USA
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29
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Levitan D, Twitto R, Levy R, Lyons LC, Susswein AJ. A brief retraining regulates the persistence and lability of a long-term memory. Learn Mem 2010; 17:402-6. [PMID: 20682809 DOI: 10.1101/lm.1820010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
An experience extending the persistence of a memory after training Aplysia californica with inedible food also allows a consolidated memory to become sensitive to consolidation blockers. Long-term (24 h) memory is initiated by 5 min of training and is dependent on protein synthesis during the first few hours after training. By contrast, a more persistent (48 h) memory is dependent on a longer training session and on a later round of protein synthesis. When presented 24 h after training, a 3-min training that produces no memory alone can cause a memory that would have persisted for only 24 h to persist for 48 h. After a 48 h memory has been consolidated, 3 min of training also makes the memory sensitive to a protein-synthesis inhibitor. These findings suggest that a function of allowing a consolidated memory to become sensitive to blockers of protein synthesis may be to allow the memory to become more persistent.
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Affiliation(s)
- David Levitan
- The Mina and Everard Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan 52900, Israel
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30
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Mammalian target of rapamycin signaling modulates photic entrainment of the suprachiasmatic circadian clock. J Neurosci 2010; 30:6302-14. [PMID: 20445056 DOI: 10.1523/jneurosci.5482-09.2010] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Inducible gene expression appears to be an essential event that couples light to entrainment of the master mammalian circadian clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus. Recently, we reported that light triggers phase-dependent activation of the mammalian target of rapamycin (mTOR) signaling pathway, a major regulator of protein synthesis, in the SCN, thus raising the possibility that mTOR-evoked mRNA translation contributes to clock entrainment. Here, we used a combination of cellular, molecular, and behavioral assays to address this question. To this end, we show that the in vivo infusion of the mTOR inhibitor rapamycin led to a significant attenuation of the phase-delaying effect of early-night light. Conversely, disruption of mTOR during the late night augmented the phase-advancing effect of light. To assess the role of mTOR signaling within the context of molecular entrainment, the effects of rapamycin on light-induced expression of PERIOD1 and PERIOD2 were examined. At both the early- and late-night time points, abrogation of mTOR signaling led to a significant attenuation of light-evoked PERIOD protein expression. Our results also reveal that light-induced mTOR activation leads to the translation of mRNAs with a 5'-terminal oligopyrimidine tract such as eukaryotic elongation factor 1A and the immediate early gene JunB. Together, these data indicate that the mTOR pathway functions as potent and selective regulator of light-evoked protein translation and SCN clock entrainment.
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31
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Weatherill DB, Dyer J, Sossin WS. Ribosomal protein S6 kinase is a critical downstream effector of the target of rapamycin complex 1 for long-term facilitation in Aplysia. J Biol Chem 2010; 285:12255-67. [PMID: 20177060 DOI: 10.1074/jbc.m109.071142] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Long-term facilitation (LTF) in Aplysia is a leading cellular model for elucidating the biochemical mechanisms of synaptic plasticity underlying learning. In Aplysia, LTF requires translational control downstream of the target of rapamycin (TOR) complex 1 (TORC1). The major known downstream targets of TORC1 are 4E binding protein (4E-BP) and S6 kinase (S6K). By removing the site within these regulators required for their interaction with TORC1, we have generated dominant negative proteins that disrupt specific pathways downstream of TORC1. Expression of dominant negative S6K, but not dominant negative 4E-BP, in Aplysia sensory neurons (SNs) blocked 24-h LTF. TORC1 is directly activated by the small GTP-binding protein, Ras homologue enriched in brain (Rheb). To determine the effects of TORC1 activation on translation in Aplysia neurons, we have examined the effects of expressing a constitutively active form of the Aplysia orthologue of Rheb, ApRheb (ApRheb(Q63L)). Expression of ApRheb(Q63L) increased 4E-BP phosphorylation and the level of general, cap-dependent translation within the SN cell soma in a rapamycin-sensitive manner. This increase in cap-dependent translation was blocked neither by dominant negative 4E-BP nor dominant negative S6K. Thus, we demonstrate that S6K is an important downstream target of TORC1 in Aplysia and that it is necessary for 24-h LTF, but not for TORC1-mediated increases in somatic cap-dependent translation.
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Affiliation(s)
- Daniel B Weatherill
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
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32
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Akins MR, Berk-Rauch HE, Fallon JR. Presynaptic translation: stepping out of the postsynaptic shadow. Front Neural Circuits 2009; 3:17. [PMID: 19915727 PMCID: PMC2776480 DOI: 10.3389/neuro.04.017.2009] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Accepted: 10/07/2009] [Indexed: 11/13/2022] Open
Abstract
The ability of the nervous system to convert transient experiences into long-lasting structural changes at the synapse relies upon protein synthesis. It has become increasingly clear that a critical subset of this synthesis occurs within the synaptic compartment. While this process has been extensively characterized in the postsynaptic compartment, the contribution of local translation to presynaptic function remains largely unexplored. However, recent evidence highlights the potential importance of translation within the presynaptic compartment. Work in cultured neurons has shown that presynaptic translation occurs specifically at synapses undergoing long-term plasticity and may contribute to the maintenance of nascent synapses. Studies from our laboratory have demonstrated that Fragile X proteins, which regulate mRNA localization and translation, are expressed at the presynaptic apparatus. Further, mRNAs encoding presynaptic proteins traffic into axons. Here we discuss recent advances in the study of presynaptic translation as well as the challenges confronting the field. Understanding the regulation of presynaptic function by local protein synthesis promises to shed new light on activity-dependent modification of synaptic architecture.
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Affiliation(s)
- Michael R Akins
- Department of Neuroscience, Brown University Providence, RI, USA
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Abstract
Activity-dependent long-term synaptic plasticity requires gene expression and protein synthesis. Identifying essential genes and studying their transcriptional and translational regulation are key steps to understanding how synaptic changes become long lasting. Recently, the enzyme poly-(ADP-ribose) polymerase 1 (PARP-1) was shown to be necessary for long-term memory (LTM) in Aplysia. Since PARP-1 decondenses chromatin, we hypothesize that this enzyme regulates the expression of specific genes essential for long-term synaptic plasticity that underlies LTM. We cloned Aplysia PARP-1 (ApPARP-1) and determined that its expression in sensory neurons is necessary for serotonin (5-HT)-mediated long-term facilitation (LTF) of sensorimotor neuron synapses. PARP enzymatic activity is also required, since transient application of PARP inhibitors blocked LTF. Differential display and RNA analysis of ganglia dissected from intact animals exposed to 5-HT identified the ribosomal RNA genes as PARP-dependent effector genes. The increase in the expression of rRNAs is long lasting and dynamic. Pulse-labeling RNA studies showed a PARP-dependent increase in rRNAs but not in the total RNA 24 h after 5-HT treatment. Moreover, the expression of both the AprpL27a (Aplysia ribosomal protein L27a) and the ApE2N (Aplysia ubiquitin-conjugating enzyme E2N) mRNAs also increased after 5-HT. Thus, our results suggest that 5-HT, in part by regulating PARP-1 activity, alters the expression of transcripts required for the synthesis of new ribosomes necessary for LTF.
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Abstract
Using a novel microfluidic chamber that allows the isolation of axons without contamination by nonaxonal material, we have for the first time purified mRNA from naive, matured CNS axons, and identified the presence of >300 mRNA transcripts. We demonstrate that the transcripts are axonal in nature, and that many of the transcripts present in uninjured CNS axons overlap with those previously identified in PNS injury-conditioned DRG axons. The axonal transcripts detected in matured cortical axons are enriched for protein translational machinery, transport, cytoskeletal components, and mitochondrial maintenance. We next investigated how the axonal mRNA pool changes after axotomy, revealing that numerous gene transcripts related to intracellular transport, mitochondria and the cytoskeleton show decreased localization 2 d after injury. In contrast, gene transcripts related to axonal targeting and synaptic function show increased localization in regenerating cortical axons, suggesting that there is an increased capacity for axonal outgrowth and targeting, and increased support for synapse formation and presynaptic function in regenerating CNS axons after injury. Our data demonstrate that CNS axons contain many mRNA species of diverse functions, and suggest that, like invertebrate and PNS axons, CNS axons synthesize proteins locally, maintaining a degree of autonomy from the cell body.
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Grange J, Belly A, Dupas S, Trembleau A, Sadoul R, Goldberg Y. Specific interaction between Sam68 and neuronal mRNAs: implication for the activity-dependent biosynthesis of elongation factor eEF1A. J Neurosci Res 2009; 87:12-25. [PMID: 18711726 DOI: 10.1002/jnr.21824] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In cultured hippocampal neurons and in adult brain, the splicing regulatory protein Sam68 is partially relocated to the somatodendritic domain and associates with dendritic polysomes. Transfer to the dendrites is activity-dependent. We have investigated the repertoire of neuronal mRNAs to which Sam68 binds in vivo. By using coimmunoprecipitation and microarray screening techniques, Sam68 was found to associate with a number of plasticity-related mRNA species, including Eef1a1, an activity-responsive mRNA coding for translation elongation factor eEF1A. In cortical neuronal cultures, translation of the Eef1a1 mRNA was strongly induced by neuronal depolarisation and correlated with enhanced association of Sam68 with polysomal mRNAs. The possible function of Sam68 in Eef1a1 mRNA utilization was studied by expressing a dominant-negative, cytoplasmic Sam68 mutant (GFP-Sam68DeltaC) in cultured hippocampal neurons. The level of eEF1A was lower in neurons expressing GFP-Sam68DeltaC than in control neurons, supporting the proposal that endogenous Sam68 may contribute to the translational efficiency of the Eef1a1 mRNA. These findings are discussed in the light of the complex, potentially crucial regulation of eEF1A biosynthesis during long-term synaptic change.
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Affiliation(s)
- Julien Grange
- Université Joseph Fourier, Grenoble Institute of Neuroscience, Grenoble, France
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Murray LM, Thomson D, Conklin A, Wishart TM, Gillingwater TH. Loss of translation elongation factor (eEF1A2) expression in vivo differentiates between Wallerian degeneration and dying-back neuronal pathology. J Anat 2009; 213:633-45. [PMID: 19094180 DOI: 10.1111/j.1469-7580.2008.01007.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Wallerian degeneration and dying-back pathology are two well-known cellular pathways capable of regulating the breakdown and loss of axonal and synaptic compartments of neurons in vivo. However, the underlying mechanisms and molecular triggers of these pathways remain elusive. Here, we show that loss of translation elongation factor eEF1A2 expression in lower motor neurons and skeletal muscle fibres in homozygous Wasted mice triggered a dying-back neuropathy. Synaptic loss at the neuromuscular junction occurred in advance of axonal pathology and by a mechanism morphologically distinct from Wallerian degeneration. Dying-back pathology in Wasted mice was accompanied by reduced expression levels of the zinc finger protein ZPR1, as found in other dying-back neuropathies such as spinal muscular atrophy. Surprisingly, experimental nerve lesion revealed that Wallerian degeneration was significantly delayed in homozygous Wasted mice; morphological assessment revealed that approximately 80% of neuromuscular junctions in deep lumbrical muscles at 24 h and approximately 50% at 48 h had retained motor nerve terminals following tibial nerve lesion. This was in contrast to wild-type and heterozygous Wasted mice where < 5% of neuromuscular junctions had retained motor nerve terminals at 24 h post-lesion. These data show that eEF1A2 expression is required to prevent the initiation of dying-back pathology at the neuromuscular junction in vivo. In contrast, loss of eEF1A2 expression significantly inhibited the initiation and progression of Wallerian degeneration in vivo. We conclude that loss of eEF1A2 expression distinguishes mechanisms underlying dying-back pathology from those responsible for Wallerian degeneration in vivo and suggest that eEF1A2-dependent cascades may provide novel molecular targets to manipulate neurodegenerative pathways in lower motor neurons.
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Affiliation(s)
- Lyndsay M Murray
- Centre for Integrative Physiology, College of Medicine, and Veterinary Medicine, University of Edinburgh, Edinburgh, EH8 9XD, UK
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Costa-Mattioli M, Sossin WS, Klann E, Sonenberg N. Translational control of long-lasting synaptic plasticity and memory. Neuron 2009; 61:10-26. [PMID: 19146809 DOI: 10.1016/j.neuron.2008.10.055] [Citation(s) in RCA: 719] [Impact Index Per Article: 47.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 10/10/2008] [Accepted: 10/17/2008] [Indexed: 01/07/2023]
Abstract
Long-lasting forms of synaptic plasticity and memory are dependent on new protein synthesis. Recent advances obtained from genetic, physiological, pharmacological, and biochemical studies provide strong evidence that translational control plays a key role in regulating long-term changes in neural circuits and thus long-term modifications in behavior. Translational control is important for regulating both general protein synthesis and synthesis of specific proteins in response to neuronal activity. In this review, we summarize and discuss recent progress in the field and highlight the prospects for better understanding of long-lasting changes in synaptic strength, learning, and memory and implications for neurological diseases.
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Affiliation(s)
- Mauro Costa-Mattioli
- Department of Biochemistry and McGill Cancer Center, McGill University, Montreal QCH3G1Y6, Canada.
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Puthanveettil SV, Monje FJ, Miniaci MC, Choi YB, Karl KA, Khandros E, Gawinowicz MA, Sheetz MP, Kandel ER. A new component in synaptic plasticity: upregulation of kinesin in the neurons of the gill-withdrawal reflex. Cell 2008; 135:960-73. [PMID: 19041756 DOI: 10.1016/j.cell.2008.11.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Revised: 07/28/2008] [Accepted: 11/04/2008] [Indexed: 01/09/2023]
Abstract
To explore how gene products, required for the initiation of synaptic growth, move from the cell body of the sensory neuron to its presynaptic terminals, and from the cell body of the motor neuron to its postsynaptic dendritic spines, we have investigated the anterograde transport machinery in both the sensory and motor neurons of the gill-withdrawal reflex of Aplysia. We found that the induction of long-term facilitation (LTF) by repeated applications of serotonin, a modulatory transmitter released during learning in Aplysia, requires upregulation of kinesin heavy chain (KHC) in both pre- and postsynaptic neurons. Indeed, upregulation of KHC in the presynaptic neurons alone is sufficient for the induction of LTF. However, KHC is not required for the persistence of LTF. Thus, in addition to transcriptional activation in the nucleus and local protein synthesis at the synapse, our studies have identified a third component critical for long-term learning-related plasticity: the coordinated upregulation of kinesin-mediated transport.
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Affiliation(s)
- Sathyanarayanan V Puthanveettil
- Department of Neuroscience, College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA
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Mansilla F, Dominguez CA, Yeadon JE, Corydon TJ, Burden SJ, Knudsen CR. Translation elongation factor eEF1A binds to a novel myosin binding protein-C-like protein. J Cell Biochem 2008; 105:847-58. [PMID: 18756455 PMCID: PMC2597023 DOI: 10.1002/jcb.21880] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Eukaryotic translation elongation factor 1A (eEF1A) is a guanine-nucleotide binding protein, which transports aminoacylated tRNA to the ribosomal A site during protein synthesis. In a yeast two-hybrid screening of a human skeletal muscle cDNA library, a novel eEF1A binding protein, immunoglobulin-like and fibronectin type III domain containing 1 (IGFN1), was discovered, and its interaction with eEF1A was confirmed in vitro. IGFN1 is specifically expressed in skeletal muscle and presents immunoglobulin I and fibronectin III sets of domains characteristic of sarcomeric proteins. IGFN1 shows sequence and structural homology to myosin binding protein-C fast and slow-type skeletal muscle isoforms. IGFN1 is substantially upregulated during muscle denervation. We propose a model in which this increased expression of IGFN1 serves to down-regulate protein synthesis via interaction with eEF1A during denervation.
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Affiliation(s)
| | | | - James E. Yeadon
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | | | - Steven J. Burden
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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Lee YS, Bailey CH, Kandel ER, Kaang BK. Transcriptional regulation of long-term memory in the marine snail Aplysia. Mol Brain 2008; 1:3. [PMID: 18803855 PMCID: PMC2546398 DOI: 10.1186/1756-6606-1-3] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Accepted: 06/17/2008] [Indexed: 12/05/2022] Open
Abstract
Whereas the induction of short-term memory involves only covalent modifications of constitutively expressed preexisting proteins, the formation of long-term memory requires gene expression, new RNA, and new protein synthesis. On the cellular level, transcriptional regulation is thought to be the starting point for a series of molecular steps necessary for both the initiation and maintenance of long-term synaptic facilitation (LTF). The core molecular features of transcriptional regulation involved in the long-term process are evolutionally conserved in Aplysia, Drosophila, and mouse, and indicate that gene regulation by the cyclic AMP response element binding protein (CREB) acting in conjunction with different combinations of transcriptional factors is critical for the expression of many forms of long-term memory. In the marine snail Aplysia, the molecular mechanisms that underlie the storage of long-term memory have been extensively studied in the monosynaptic connections between identified sensory neuron and motor neurons of the gill-withdrawal reflex. One tail shock or one pulse of serotonin (5-HT), a modulatory transmitter released by tail shocks, produces a transient facilitation mediated by the cAMP-dependent protein kinase leading to covalent modifications in the sensory neurons that results in an enhancement of transmitter release and a strengthening of synaptic connections lasting minutes. By contrast, repeated pulses of 5-hydroxytryptamine (5-HT) induce a transcription- and translation-dependent long-term facilitation (LTF) lasting more than 24 h and trigger the activation of a family of transcription factors in the presynaptic sensory neurons including ApCREB1, ApCREB2 and ApC/EBP. In addition, we have recently identified novel transcription factors that modulate the expression of ApC/EBP and also are critically involved in LTF. In this review, we examine the roles of these transcription factors during consolidation of LTF induced by different stimulation paradigms.
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Affiliation(s)
- Yong-Seok Lee
- National Creative Research Initiative Center for Memory, Department of Biological Sciences, Seoul National University, Korea
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mGluR-dependent long-term depression is associated with increased phosphorylation of S6 and synthesis of elongation factor 1A but remains expressed in S6K-deficient mice. Mol Cell Biol 2008; 28:2996-3007. [PMID: 18316404 DOI: 10.1128/mcb.00201-08] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Metabotropic glutamate receptor-dependent long-term depression (mGluR-LTD) in the hippocampus requires rapid protein synthesis, which suggests that mGluR activation is coupled to signaling pathways that regulate translation. Herein, we have investigated the signaling pathways that couple group I mGluRs to ribosomal S6 protein phosphorylation and 5'oligopyrimidine tract (5'TOP)-encoded protein synthesis during mGluR-LTD. We found that mGluR-LTD was associated with increased phosphorylation of p70S6 kinase (S6K1) and S6, as well as the synthesis of the 5'TOP-encoded protein elongation factor 1A (EF1A). Moreover, we found that LTD-associated increases in S6K1 phosphorylation, S6 phosphorylation, and levels of EF1A were sensitive to inhibitors of phosphoinositide 3-kinase (PI3K), mammalian target of rapamycin (mTOR), and extracellular signal-regulated kinase (ERK). However, mGluR-LTD was normal in S6K1 knockout mice and enhanced in both S6K2 knockout mice and S6K1/S6K2 double knockout mice. In addition, we observed that LTD-associated increases in S6 phosphorylation were still increased in S6K1- and S6K2-deficient mice, whereas basal levels of EF1A were abnormally elevated. Taken together, these findings indicate that mGluR-LTD is associated with PI3K-, mTOR-, and ERK-dependent alterations in the phosphorylation of S6 and S6K. Our data also suggest that S6Ks are not required for the expression of mGluR-LTD and that the synthesis of 5'TOP-encoded proteins is independent of S6Ks during mGluR-LTD.
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Synapse-specific stabilization of plasticity processes: The synaptic tagging and capture hypothesis revisited 10 years later. Neurosci Biobehav Rev 2008; 32:831-51. [DOI: 10.1016/j.neubiorev.2008.01.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 12/28/2007] [Accepted: 01/07/2008] [Indexed: 11/22/2022]
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Bluem R, Schmidt E, Corvey C, Karas M, Schlicksupp A, Kirsch J, Kuhse J. Components of the Translational Machinery Are Associated with Juvenile Glycine Receptors and Are Redistributed to the Cytoskeleton upon Aging and Synaptic Activity. J Biol Chem 2007; 282:37783-93. [DOI: 10.1074/jbc.m708301200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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45
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Poon MM, Choi SH, Jamieson CAM, Geschwind DH, Martin KC. Identification of process-localized mRNAs from cultured rodent hippocampal neurons. J Neurosci 2007; 26:13390-9. [PMID: 17182790 PMCID: PMC6675000 DOI: 10.1523/jneurosci.3432-06.2006] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The regulated translation of localized mRNAs in neurons provides a mechanism for spatially restricting gene expression in a synapse-specific manner. To identify the population of mRNAs present in distal neuronal processes of rodent hippocampal neurons, we grew neurons on polycarbonate filters etched with 3 microm pores. Although the neuronal cell bodies remained on the top surface of the filters, dendrites, axons, and glial processes penetrated through the pores to grow along the bottom surface of the membrane where they could be mechanically separated from cell bodies. Quantitative PCR and immunochemical analyses of the process preparation revealed that it was remarkably free of somatic contamination. Microarray analysis of RNA isolated from the processes identified over 100 potentially localized mRNAs. In situ hybridization studies of 19 of these transcripts confirmed that all 19 were present in dendrites, validating the utility of this approach for identifying dendritically localized transcripts. Many of the identified mRNAs encoded components of the translational machinery and several were associated with the RNA-binding protein Staufen. These findings indicate that there is a rich repertoire of mRNAs whose translation can be locally regulated and support the emerging idea that local protein synthesis serves to boost the translational capacity of synapses.
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Affiliation(s)
| | | | | | - Daniel H. Geschwind
- Program in Neurogenetics, Department of Neurology
- Department of Human Genetics
- Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, and
| | - Kelsey C. Martin
- Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, and
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095
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Niibori Y, Hayashi F, Hirai K, Matsui M, Inokuchi K. Alternative poly(A) site-selection regulates the production of alternatively spliced vesl-1/homer1 isoforms that encode postsynaptic scaffolding proteins. Neurosci Res 2006; 57:399-410. [PMID: 17196693 DOI: 10.1016/j.neures.2006.11.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 11/22/2006] [Accepted: 11/29/2006] [Indexed: 12/23/2022]
Abstract
The vesl-1/homer1 gene encodes a scaffold protein that interacts with several receptors to modulate synaptic functions. The gene also encodes two shorter forms that counteract the functions of the long form of Vesl. Expression of the shorter forms is driven by neural activities such as long-term potentiation. Here we analyzed the mechanism regulating vesl-1 alternative splicing. Each functional poly(A) site was in a different part of the 3'-terminal exon, with promoter-proximal and promoter-distal sites at the end of exons corresponding to the short and long form Vesl-1, respectively. 3'-End-processing at proximal poly(A) site, specifically at the vesl-1M poly(A) site, was enhanced by extracellular stimuli, thereby switching transcription termination from promoter-distal to -proximal poly(A) site. This switch was not specifically coupled to the vesl-1 promoter and was independent of de novo protein synthesis. Analysis of transcripts from mini-genes that mimic the structure of endogenous vesl-1 revealed that the vesl-1M poly(A) region plays a crucial role in switching to the alternative pre-mRNA splicing that is triggered by extracellular stimuli. Therefore, a 3'-end-processing event regulates the neural activity-dependent alternative splicing of vesl-1. This is the first report of a gene in which alternative poly(A) site-selection regulates alternative splicing in a protein synthesis-independent manner.
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Affiliation(s)
- Yosuke Niibori
- Mitsubishi Kagaku Institute of Life Sciences (MITILS), 11 Minamiooya, Machida, Tokyo, Japan
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47
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Matsumoto M, Setou M, Inokuchi K. Transcriptome analysis reveals the population of dendritic RNAs and their redistribution by neural activity. Neurosci Res 2006; 57:411-23. [PMID: 17207874 DOI: 10.1016/j.neures.2006.11.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Revised: 11/27/2006] [Accepted: 11/30/2006] [Indexed: 11/26/2022]
Abstract
Subcellular localization of RNA is an efficient way to localize proteins to a specific region of a cell. The dendritic localization of RNAs underlies the establishment and maintenance of the synaptic functions of neuronal cells. A requirement for dendritic RNA localization and subsequent local translation has been demonstrated in several forms of experience-dependent synaptic plasticity. In spite of several attempts to identify these RNAs, the population of RNA species present in dendrites as a whole has not been well described. Here we show the results of microarray analyses with RNAs isolated from heavy portion of polysome (HP) fraction where RNA granules are enriched in and synaptosome fraction, prepared from the rat brain. These analyses revealed the complex nature of the dendritic RNA population, which included RNAs that were not expected to be in the dendrites. Neural activity caused by an electroconvulsive shock triggered a redistribution of the population of dendritic transcriptome towards the area of overlap between the HP and the synaptosome, which is assumed to be neck of spine. This redistribution may accompany some changes in the translatability of those transcriptome, which suggests complex mechanisms of local translation in response to synaptic inputs.
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Affiliation(s)
- Mineo Matsumoto
- Memory Formation and Psychiatric Disorder Research Group, Mitsubishi Kagaku Institute of Life Sciences, MITILS, 11 Minamiooya, Machida, Tokyo, Japan
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48
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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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49
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Abstract
Considerable evidence suggests that the formation of long-term memories requires a critical period of new protein synthesis. Recently, the notion that some of these newly synthesized proteins originate through local translation in neuronal dendrites has gained some traction. Here, we review the experimental support for this idea and highlight some of the key questions outstanding in this area.
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Affiliation(s)
- Michael A Sutton
- Division of Biology 114-96, California Institute of Technology, Howard Hughes Medical Institute, Pasadena, CA 91125, USA
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50
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Liu J, Hu JY, Wu F, Schwartz JH, Schacher S. Two mRNA-binding proteins regulate the distribution of syntaxin mRNA in Aplysia sensory neurons. J Neurosci 2006; 26:5204-14. [PMID: 16687512 PMCID: PMC6674263 DOI: 10.1523/jneurosci.4917-05.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Targeting mRNAs to different functional domains within neurons is crucial to memory storage. In Aplysia sensory neurons, syntaxin mRNA accumulates at the axon hillock during long-term facilitation of sensory-motor neuron synapses produced by serotonin (5-HT). We find that the 3' untranslated region of Aplysia syntaxin mRNA has two targeting elements, the cytosolic polyadenylation element (CPE) and stem-loop double-stranded structures that appear to interact with mRNA-binding proteins CPEB and Staufen. Blocking the interaction between these targeting elements and their RNA-binding proteins abolished both accumulation at the axon hillock and long-term facilitation. CPEB, which we previously have shown to be upregulated after stimulation with 5-HT, is required for the relocalization of syntaxin mRNA to the axon hillock from the opposite pole in the cell body of the sensory neuron during long-term facilitation, whereas Staufen is required for maintaining the accumulation of the mRNA both at the axon hillock after the treatment with 5-HT and at the opposite pole in stable, unstimulated sensory neurons. Thus, the cooperative actions of the two mRNA-binding proteins serve to direct the distribution of an mRNA encoding a key synaptic protein.
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Affiliation(s)
- Jinming Liu
- Center for Neurobiology and Behavior, College of Physicians and Surgeons, Columbia University, New York State Psychiatric Institute, New York, New York 10032, USA
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