1
|
Wu W, Chen P, Yang J, Liu Y. A Low Dose of Rapamycin Promotes Hair Cell Differentiation by Enriching SOX2 + Progenitors in the Neonatal Mouse Inner Ear Organoids. J Assoc Res Otolaryngol 2024; 25:149-165. [PMID: 38472516 PMCID: PMC11018585 DOI: 10.1007/s10162-024-00938-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 02/15/2024] [Indexed: 03/14/2024] Open
Abstract
PURPOSE To investigate the impact of rapamycin on the differentiation of hair cells. METHODS Murine cochlear organoids were derived from cochlear progenitor cells. Different concentrations of rapamycin were added into the culture medium at different proliferation and differentiation stages. RESULTS Rapamycin exhibited a concentration-dependent reduction in the proliferation of these inner ear organoids. Nevertheless, organoids subjected to a 10-nM dose of rapamycin demonstrated a markedly increased proportion of hair cells. Furthermore, rapamycin significantly upregulated the expression of markers associated with both hair cells and supporting cells, including ATOH1, MYO7A, and SOX2. Mechanistic studies revealed that rapamycin preferentially suppressed cells without Sox2 expression during the initial proliferation stage, thereby augmenting and refining the population of SOX2+ progenitors. These enriched progenitors were predisposed to differentiate into hair cells during the later stages of organoid development. Conversely, the use of the mTOR activator MHY 1485 demonstrated opposing effects. CONCLUSION Our findings underscore a practical strategy for enhancing the generation of inner ear organoids with a low dose of rapamycin, achieved by enriching SOX2+ progenitors in an in vitro setting.
Collapse
Affiliation(s)
- Wenjin Wu
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Penghui Chen
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Jun Yang
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| | - Yupeng Liu
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| |
Collapse
|
2
|
Hobson BD, Kong L, Angelo MF, Lieberman OJ, Mosharov EV, Herzog E, Sulzer D, Sims PA. Subcellular and regional localization of mRNA translation in midbrain dopamine neurons. Cell Rep 2022; 38:110208. [PMID: 35021090 PMCID: PMC8844886 DOI: 10.1016/j.celrep.2021.110208] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 10/25/2021] [Accepted: 12/13/2021] [Indexed: 12/12/2022] Open
Abstract
Midbrain dopaminergic (mDA) neurons exhibit extensive dendritic and axonal arborizations, but local protein synthesis is not characterized in these neurons. Here, we investigate messenger RNA (mRNA) localization and translation in mDA neuronal axons and dendrites, both of which release dopamine (DA). Using highly sensitive ribosome-bound RNA sequencing and imaging approaches, we find no evidence for mRNA translation in mDA axons. In contrast, mDA neuronal dendrites in the substantia nigra pars reticulata (SNr) contain ribosomes and mRNAs encoding the major components of DA synthesis, release, and reuptake machinery. Surprisingly, we also observe dendritic localization of mRNAs encoding synaptic vesicle-related proteins, including those involved in exocytic fusion. Our results are consistent with a role for local translation in the regulation of DA release from dendrites, but not from axons. Our translatome data define a molecular signature of sparse mDA neurons in the SNr, including the enrichment of Atp2a3/SERCA3, an atypical ER calcium pump.
Collapse
Affiliation(s)
- Benjamin D Hobson
- Department of Systems Biology, Columbia University Irving Medical Center, New York 10032, NY, USA; Medical Scientist Training Program, Columbia University Irving Medical Center, New York, NY 10032, USA; Department of Psychiatry, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Linghao Kong
- Department of Systems Biology, Columbia University Irving Medical Center, New York 10032, NY, USA
| | - Maria Florencia Angelo
- Interdisciplinary Institute for Neuroscience, Université de Bordeaux, Bordeaux, France; Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - Ori J Lieberman
- Medical Scientist Training Program, Columbia University Irving Medical Center, New York, NY 10032, USA; Department of Psychiatry, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Eugene V Mosharov
- Department of Psychiatry, Columbia University Irving Medical Center, New York, NY 10032, USA; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Etienne Herzog
- Interdisciplinary Institute for Neuroscience, Université de Bordeaux, Bordeaux, France; Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France.
| | - David Sulzer
- Department of Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA; Department of Psychiatry, Columbia University Irving Medical Center, New York, NY 10032, USA; Department of Pharmacology, Columbia University Irving Medical Center, New York, NY 10032, USA; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, USA.
| | - Peter A Sims
- Department of Systems Biology, Columbia University Irving Medical Center, New York 10032, NY, USA; Department of Biochemistry & Molecular Biophysics, Columbia University Irving Medical Center, New York, NY 10032, USA; Sulzberger Columbia Genome Center, Columbia University Irving Medical Center, New York, NY 10032, USA; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, USA.
| |
Collapse
|
3
|
Robbins M, Clayton E, Kaminski Schierle GS. Synaptic tau: A pathological or physiological phenomenon? Acta Neuropathol Commun 2021; 9:149. [PMID: 34503576 PMCID: PMC8428049 DOI: 10.1186/s40478-021-01246-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 08/12/2021] [Indexed: 12/17/2022] Open
Abstract
In this review, we discuss the synaptic aspects of Tau pathology occurring during Alzheimer's disease (AD) and how this may relate to memory impairment, a major hallmark of AD. Whilst the clinical diagnosis of AD patients is a loss of working memory and long-term declarative memory, the histological diagnosis is the presence of neurofibrillary tangles of hyperphosphorylated Tau and Amyloid-beta plaques. Tau pathology spreads through synaptically connected neurons to impair synaptic function preceding the formation of neurofibrillary tangles, synaptic loss, axonal retraction and cell death. Alongside synaptic pathology, recent data suggest that Tau has physiological roles in the pre- or post- synaptic compartments. Thus, we have seen a shift in the research focus from Tau as a microtubule-stabilising protein in axons, to Tau as a synaptic protein with roles in accelerating spine formation, dendritic elongation, and in synaptic plasticity coordinating memory pathways. We collate here the myriad of emerging interactions and physiological roles of synaptic Tau, and discuss the current evidence that synaptic Tau contributes to pathology in AD.
Collapse
|
4
|
Cui F, Gu S, Gu Y, Yin J, Fang C, Liu L. Alteration in the mRNA expression profile of the autophagy-related mTOR pathway in schizophrenia patients treated with olanzapine. BMC Psychiatry 2021; 21:388. [PMID: 34348681 PMCID: PMC8335969 DOI: 10.1186/s12888-021-03394-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 07/26/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The mammalian target of rapamycin protein (mTOR) signaling pathway is involved in the pathogenesis of schizophrenia and the mechanism of extrapyramidal adverse reactions to antipsychotic drugs, which might be mediated by an mTOR-dependent autophagy impairment. This study aimed to examine the expression of mTOR pathway genes in patients with schizophrenia treated with olanzapine, which is considered an mTOR inhibitor and autophagy inducer. METHODS Thirty-two patients with acute schizophrenia who had been treated with olanzapine for four weeks (average dose 14.24 ± 4.35 mg/d) and 32 healthy volunteers were recruited. Before and after olanzapine treatment, the Positive and Negative Syndrome Scale (PANSS) was used to evaluate the symptoms of patients with schizophrenia, and the mRNA expression levels of mTOR pathway-related genes, including MTOR, RICTOR, RAPTOR, and DEPTOR, were detected in fasting venous blood samples from all subjects using real-time quantitative PCR. RESULTS The MTOR and RICTOR mRNA expression levels in patients with acute schizophrenia were significantly decreased compared with those of healthy controls and further significantly decreased after four weeks of olanzapine treatment. The DEPTOR mRNA expression levels in patients with acute schizophrenia were not significantly different from those of healthy controls but were significantly increased after treatment. The expression levels of the RAPTOR mRNA were not significantly different among the three groups. The pairwise correlations of MTOR, DEPTOR, RAPTOR, and RICTOR mRNA expression levels in patients with acute schizophrenia and healthy controls were significant. After olanzapine treatment, the correlations between the expression levels of the DEPTOR and MTOR mRNAs and between the DEPTOR and RICTOR mRNAs disappeared. CONCLUSIONS Abnormalities in the mTOR pathway, especially DEPTOR and mTORC2, might play important roles in the autophagy mechanism underlying the pathophysiology of schizophrenia and effects of olanzapine treatment.
Collapse
Affiliation(s)
- Fengwei Cui
- grid.89957.3a0000 0000 9255 8984Department of Geriatric Psychiatry, Wuxi Mental Health Center, Nanjing Medical University, Wuxi, 214151 Jiangsu China
| | - Shuguang Gu
- grid.89957.3a0000 0000 9255 8984Department of Geriatric Psychiatry, Wuxi Mental Health Center, Nanjing Medical University, Wuxi, 214151 Jiangsu China
| | - Yue Gu
- grid.89957.3a0000 0000 9255 8984The First Clinical Medical College, Nanjing Medical University, Nanjing, 211166 Jiangsu China
| | - Jiajun Yin
- grid.89957.3a0000 0000 9255 8984Department of Geriatric Psychiatry, Wuxi Mental Health Center, Nanjing Medical University, Wuxi, 214151 Jiangsu China
| | - Chunxia Fang
- Combined TCM & Western Medicine Department, Wuxi Mental Health Center, Nanjing Medical University, Wuxi, 214151, Jiangsu, China.
| | - Liang Liu
- Department of Geriatric Psychiatry, Wuxi Mental Health Center, Nanjing Medical University, Wuxi, 214151, Jiangsu, China.
| |
Collapse
|
5
|
Gobert D, Schohl A, Kutsarova E, Ruthazer ES. TORC1 selectively regulates synaptic maturation and input convergence in the developing visual system. Dev Neurobiol 2020; 80:332-350. [DOI: 10.1002/dneu.22782] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 08/07/2020] [Accepted: 09/16/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Delphine Gobert
- Montreal Neurological Institute‐Hospital McGill University Montreal QC Canada
| | - Anne Schohl
- Montreal Neurological Institute‐Hospital McGill University Montreal QC Canada
| | - Elena Kutsarova
- Montreal Neurological Institute‐Hospital McGill University Montreal QC Canada
| | - Edward S. Ruthazer
- Montreal Neurological Institute‐Hospital McGill University Montreal QC Canada
| |
Collapse
|
6
|
Guo G, Kang L, Geng D, Han S, Li S, Du J, Wang C, Cui H. Testosterone modulates structural synaptic plasticity of primary cultured hippocampal neurons through ERK - CREB signalling pathways. Mol Cell Endocrinol 2020; 503:110671. [PMID: 31805308 DOI: 10.1016/j.mce.2019.110671] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 11/24/2019] [Accepted: 11/30/2019] [Indexed: 11/27/2022]
Abstract
Although hippocampus-derived androgens play an important role in hippocampal synaptic plasticity, studies at the cellular level have received relatively less attention. Furthermore, the underlying signalling pathways associated with synaptic plasticity remain unclear. Results of the present study demonstrated that testosterone treatment of primary cultured rat hippocampal neurons resulted in a rapid increase in spine density, accompanied by the elevation of protein and messenger RNA levels of synaptophysin, developmentally regulated brain protein (Drebrin), and the N-methyl-D-aspartate receptor NR1 subunit. Testosterone treatment also increased the phosphorylation levels of extracellular-regulated protein kinase (ERK)1/2 and cAMP-responsive element binding protein (CREB), rather than p38 and Jun N-terminal kinase (JNK). U0126 significantly reversed the testosterone-mediated phosphorylation of CREB. Importantly, the increase in spine density was not induced by testosterone under U0126 treatment. These findings suggest that the ERK1/2-CREB signalling pathway plays an important role in testosterone-mediated rapid spinogenesis of cultured rat hippocampal neurons. Results of this study will be helpful in further clarifying the physiological function of testosterone and related signalling pathways in vitro.
Collapse
Affiliation(s)
- Guoxin Guo
- Department of Anatomy, Hebei Medical University, Shijiazhuang, China
| | - Lin Kang
- Department of Anatomy, Hebei Medical University, Shijiazhuang, China
| | - Dandan Geng
- Department of Anatomy, Hebei Medical University, Shijiazhuang, China
| | - Shuo Han
- Department of Anatomy, Hebei Medical University, Shijiazhuang, China
| | - Sha Li
- Department of Anatomy, Hebei Medical University, Shijiazhuang, China; Neuroscience Research Center, Hebei Medical University, Shijiazhuang, China; Human Brain Bank, Hebei Medical University, Shijiazhuang, China
| | - Juan Du
- Department of Anatomy, Hebei Medical University, Shijiazhuang, China; Neuroscience Research Center, Hebei Medical University, Shijiazhuang, China; Human Brain Bank, Hebei Medical University, Shijiazhuang, China
| | - Chang Wang
- Department of Anatomy, Hebei Medical University, Shijiazhuang, China
| | - Huixian Cui
- Department of Anatomy, Hebei Medical University, Shijiazhuang, China; Neuroscience Research Center, Hebei Medical University, Shijiazhuang, China; Human Brain Bank, Hebei Medical University, Shijiazhuang, China.
| |
Collapse
|
7
|
Arey RN, Kaletsky R, Murphy CT. Nervous system-wide profiling of presynaptic mRNAs reveals regulators of associative memory. Sci Rep 2019; 9:20314. [PMID: 31889133 PMCID: PMC6937282 DOI: 10.1038/s41598-019-56908-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 12/17/2019] [Indexed: 12/17/2022] Open
Abstract
Presynaptic protein synthesis is important in the adult central nervous system; however, the nervous system-wide set of mRNAs localized to presynaptic areas has yet to be identified in any organism. Here we differentially labeled somatic and synaptic compartments in adult C. elegans with fluorescent proteins, and isolated synaptic and somatic regions from the same population of animals. We used this technique to determine the nervous system-wide presynaptic transcriptome by deep sequencing. Analysis of the synaptic transcriptome reveals that synaptic transcripts are predicted to have specialized functions in neurons. Differential expression analysis identified 542 genes enriched in synaptic regions relative to somatic regions, with synaptic functions conserved in higher organisms. We find that mRNAs for pumilio RNA-binding proteins are abundant in synaptic regions, which we confirmed through high-sensitivity in situ hybridization. Presynaptic PUMILIOs regulate associative memory. Our approach enables the identification of new mechanisms that regulate synaptic function and behavior.
Collapse
Affiliation(s)
- Rachel N Arey
- Department of Molecular and Cellular Biology and Center for Precision Environmental Health, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Molecular Biology & LSI Genomics, Princeton University, Princeton, NJ, 08544, USA
| | - Rachel Kaletsky
- Department of Molecular Biology & LSI Genomics, Princeton University, Princeton, NJ, 08544, USA
| | - Coleen T Murphy
- Department of Molecular Biology & LSI Genomics, Princeton University, Princeton, NJ, 08544, USA.
| |
Collapse
|
8
|
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.
Collapse
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
| |
Collapse
|
9
|
Koren SA, Gillett DA, D'Alton SV, Hamm MJ, Abisambra JF. Proteomic Techniques to Examine Neuronal Translational Dynamics. Int J Mol Sci 2019; 20:ijms20143524. [PMID: 31323794 PMCID: PMC6678648 DOI: 10.3390/ijms20143524] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 07/08/2019] [Accepted: 07/15/2019] [Indexed: 01/30/2023] Open
Abstract
Impairments in translation have been increasingly implicated in the pathogenesis and progression of multiple neurodegenerative diseases. Assessing the spatiotemporal dynamics of translation in the context of disease is a major challenge. Recent developments in proteomic analyses have enabled the resolution of nascent peptides in a short timescale on the order of minutes. In addition, a quantitative analysis of translation has progressed in vivo, showing remarkable potential for coupling these techniques with cognitive and behavioral outcomes. Here, we review these modern approaches to measure changes in translation and ribosomal function with a specific focus on current applications in the mammalian brain and in the study of neurodegenerative diseases.
Collapse
Affiliation(s)
- Shon A Koren
- Department of Neuroscience and Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL 32601, USA
| | - Drew A Gillett
- Department of Neuroscience and Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL 32601, USA
| | - Simon V D'Alton
- Department of Neuroscience and Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL 32601, USA
| | - Matthew J Hamm
- Department of Neuroscience and Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL 32601, USA
| | - Jose F Abisambra
- Department of Neuroscience and Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL 32601, USA.
| |
Collapse
|
10
|
Jing D, Li D, Peng C, Chen Y, Behnisch T. Role of microtubules in late-associative plasticity of hippocampal Schaffer collateral-CA1 synapses in mice. Neurobiol Learn Mem 2019; 163:107038. [PMID: 31278986 DOI: 10.1016/j.nlm.2019.107038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 04/13/2019] [Accepted: 07/02/2019] [Indexed: 11/17/2022]
Abstract
The microtubule network represents a key scaffolding structure that forms part of the neuronal cytoskeleton and contributes to biomolecule exchange within neurons. However, researchers have not determined whether an intact microtubule network is required for late associative plasticity. Therefore, the late associative plasticity of field excitatory postsynaptic potentials from two synaptic inputs was analyzed. Synaptic potentiation was induced through alternating tetanization of hippocampal Schaffer-collateral CA1 synaptic populations in acute slices prepared from young-adult C57BL/6 mice. Vincristine was applied to depolymerize microtubules. Vincristine did not alter the phosphorylation levels of plasticity-related pre- or postsynaptic proteins but reduced the level of a protein marker of the ER-Golgi intermediate compartment (ERGIC-53/p58). Vincristine did not alter the magnitude or maintenance of the synaptic potentiation evoked by repeated tetanization (3 × 100 stimuli at 100 Hz) of one synaptic population. However, this synaptic potentiation was sensitive to the coapplication of a protein synthesis inhibitor, such as rapamycin, anisomycin or cycloheximide, indicating that protein synthesis has become essential in depolymerized microtubules during the first hour of the synaptic potentiation. The application of vincristine up to a 70 stimuli, 100 Hz tetanization of a second synaptic input prevented the transformation of short-term potentiation into long-term potentiation (LTP), further indicating that intact microtubules are required for the late associative properties of synaptic plasticity. Therefore, activity-dependent synaptic plasticity does not rely on microtubules within the first two hours after tetanization; however, the associative interaction of independent synaptic inputs relies on their proper function. In addition, either new protein synthesis or microtubule-based processes are sufficient to stabilize LTP within the first 3 h after tetanization, and a deficit in synaptic plasticity is only observable when both processes are blocked.
Collapse
Affiliation(s)
- Dongqing Jing
- Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Dongxue Li
- Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Cheng Peng
- Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Ying Chen
- Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Thomas Behnisch
- Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China.
| |
Collapse
|
11
|
Ostroff LE, Watson DJ, Cao G, Parker PH, Smith H, Harris KM. Shifting patterns of polyribosome accumulation at synapses over the course of hippocampal long-term potentiation. Hippocampus 2018; 28:416-430. [PMID: 29575288 DOI: 10.1002/hipo.22841] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 02/28/2018] [Accepted: 03/11/2018] [Indexed: 11/09/2022]
Abstract
Hippocampal long-term potentiation (LTP) is a cellular memory mechanism. For LTP to endure, new protein synthesis is required immediately after induction and some of these proteins must be delivered to specific, presumably potentiated, synapses. Local synthesis in dendrites could rapidly provide new proteins to synapses, but the spatial distribution of translation following induction of LTP is not known. Here, we quantified polyribosomes, the sites of local protein synthesis, in CA1 stratum radiatum dendrites and spines from postnatal day 15 rats. Hippocampal slices were rapidly fixed at 5, 30, or 120 min after LTP induction by theta-burst stimulation (TBS). Dendrites were reconstructed through serial section electron microscopy from comparable regions near the TBS or control electrodes in the same slice, and in unstimulated hippocampus that was perfusion-fixed in vivo. At 5 min after induction of LTP, polyribosomes were elevated in dendritic shafts and spines, especially near spine bases and in spine heads. At 30 min, polyribosomes remained elevated only in spine bases. At 120 min, both spine bases and spine necks had elevated polyribosomes. Polyribosomes accumulated in spines with larger synapses at 5 and 30 min, but not at 120 min. Small spines, meanwhile, proliferated dramatically by 120 min, but these largely lacked polyribosomes. The number of ribosomes per polyribosome is variable and may reflect differences in translation regulation. In dendritic spines, but not shafts, there were fewer ribosomes per polyribosome in the slice conditions relative to in vivo, but this recovered transiently in the 5 min LTP condition. Overall, our data show that LTP induces a rapid, transient upregulation of large polyribosomes in larger spines, and a persistent upregulation of small polyribosomes in the bases and necks of small spines. This is consistent with local translation supporting enlargement of potentiated synapses within minutes of LTP induction.
Collapse
Affiliation(s)
- Linnaea E Ostroff
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269
| | - Deborah J Watson
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78731
| | - Guan Cao
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78731
| | - Patrick H Parker
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78731
| | - Heather Smith
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78731
| | - Kristen M Harris
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78731
| |
Collapse
|
12
|
Bourke AM, Bowen AB, Kennedy MJ. New approaches for solving old problems in neuronal protein trafficking. Mol Cell Neurosci 2018; 91:48-66. [PMID: 29649542 DOI: 10.1016/j.mcn.2018.04.004] [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] [Received: 02/06/2018] [Revised: 04/05/2018] [Accepted: 04/06/2018] [Indexed: 11/16/2022] Open
Abstract
Fundamental cellular properties are determined by the repertoire and abundance of proteins displayed on the cell surface. As such, the trafficking mechanisms for establishing and maintaining the surface proteome must be tightly regulated for cells to respond appropriately to extracellular cues, yet plastic enough to adapt to ever-changing environments. Not only are the identity and abundance of surface proteins critical, but in many cases, their regulated spatial positioning within surface nanodomains can greatly impact their function. In the context of neuronal cell biology, surface levels and positioning of ion channels and neurotransmitter receptors play essential roles in establishing important properties, including cellular excitability and synaptic strength. Here we review our current understanding of the trafficking pathways that control the abundance and localization of proteins important for synaptic function and plasticity, as well as recent technological advances that are allowing the field to investigate protein trafficking with increasing spatiotemporal precision.
Collapse
Affiliation(s)
- Ashley M Bourke
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Aaron B Bowen
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Matthew J Kennedy
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States.
| |
Collapse
|
13
|
Olde Engberink A, Hernandez R, de Graan P, Gruol DL. Rapamycin-Sensitive Late-LTP is Enhanced in the Hippocampus of IL-6 Transgenic Mice. Neuroscience 2017; 367:200-210. [PMID: 29104031 DOI: 10.1016/j.neuroscience.2017.10.040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/07/2017] [Accepted: 10/27/2017] [Indexed: 12/13/2022]
Abstract
The neuroimmune factor IL-6 has been shown to regulate hippocampal long-term potentiation (LTP), an activity-dependent enhancement of synaptic transmission that plays a central role in memory and learning. This IL-6 action was demonstrated with relatively short IL-6 exposure, and may reflect physiological actions of IL-6. IL-6 is also expressed chronically at elevated levels in the central nervous system (CNS) under pathological conditions such as neurological disorders. Little is known about the effects IL-6 on LTP under such conditions, an issue that we are addressing by electrophysiological recordings from CA1 pyramidal neurons of hippocampal slices from transgenic mice that persistently express elevated levels of IL-6 in the CNS (IL-6 tg). The current studies examined the long-lasting phase of LTP (late LTP; L-LTP) and the potential involvement mammalian target of rapamycin (mTOR), a known regulator of L-LTP and a downstream partner of IL-6 signal transduction pathways. Results show that basal synaptic transmission and L-LTP were increased in hippocampal slices from IL-6 tg mice compared to slices from non-transgenic (non-tg) control mice. An inhibitor of mTOR, rapamycin, reduced L-LTP in slices from both genotypes, and eliminated the difference in magnitude of L-LTP between IL-6 and non-tg hippocampus. There were no genotypic effect of rapamycin on basal synaptic transmission, but synaptic responses during the LTP induction protocol were reduced in IL-6 tg slices, an effect that could contribute to the reduction of L-LTP in the IL-6 tg slices. These results indicate that persistently increased levels of IL-6 can lead to alterations in mTOR regulation of L-LTP, possibly affecting learning and memory.
Collapse
Affiliation(s)
- Anneke Olde Engberink
- Neuroscience Department, The Scripps Research Institute, San Diego, USA; Department of Translational Neuroscience, Brain Center Rudolf Magnus, UMC Utrecht, Utrecht, Netherlands
| | - Ruben Hernandez
- Neuroscience Department, The Scripps Research Institute, San Diego, USA
| | - Pierre de Graan
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, UMC Utrecht, Utrecht, Netherlands
| | - Donna L Gruol
- Neuroscience Department, The Scripps Research Institute, San Diego, USA.
| |
Collapse
|
14
|
Levin N, Kritman M, Maroun M, Akirav I. Differential roles of the infralimbic and prelimbic areas of the prefrontal cortex in reconsolidation of a traumatic memory. Eur Neuropsychopharmacol 2017. [PMID: 28647452 DOI: 10.1016/j.euroneuro.2017.06.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Studies about reconsolidation of conditioned fear memories have shown that pharmacological manipulation at memory reactivation can attenuate or enhance the subsequent expression of the conditioned fear response. Here we examined the effects of a single injection of the mTOR inhibitor rapamycin (Rap) into the infralimbic (IL) and prelimbic (PL) areas [which compose the ventromedial prefrontal cortex (PFC)] on reconsolidation and extinction of a traumatic fear memory. We found opposite effects of Rap infused into the PL and IL on reconsolidation and extinction: intra-PL Rap and systemic Rap impaired reconsolidation and facilitated extinction whereas intra-IL Rap enhanced reconsolidation and impaired extinction. These effects persisted at least 10 days after reactivation. Shock exposure induced anxiety-like behavior and impaired working memory and intra-IL and -PL Rap normalized these effects. Finally, when measured after fear retrieval, shocked rats exhibited reduced and increased phosphorylated p70s6K levels in the IL and basolateral amygdala, respectively. No effect on phosphorylated p70s6K levels was observed in the PL. The study points to the differential roles of the IL and PL in memory reconsolidation and extinction. Moreover, inhibiting mTOR via rapamycin following reactivation of a fear memory may be a novel approach in attenuating enhanced fear memories.
Collapse
Affiliation(s)
- Natali Levin
- Department of Psychology, University of Haifa, Haifa 3498838, Israel
| | - Milly Kritman
- Sagol Department of Neurobiology, University of Haifa, Haifa 3498838, Israel
| | - Mouna Maroun
- Sagol Department of Neurobiology, University of Haifa, Haifa 3498838, Israel
| | - Irit Akirav
- Department of Psychology, University of Haifa, Haifa 3498838, Israel.
| |
Collapse
|
15
|
Abbas AK, Villers A, Ris L. Temporal phases of long-term potentiation (LTP): myth or fact? Rev Neurosci 2016; 26:507-46. [PMID: 25992512 DOI: 10.1515/revneuro-2014-0072] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 03/12/2015] [Indexed: 12/11/2022]
Abstract
Long-term potentiation (LTP) remains the most widely accepted model for learning and memory. In accordance with this belief, the temporal differentiation of LTP into early and late phases is accepted as reflecting the differentiation of short-term and long-term memory. Moreover, during the past 30 years, protein synthesis inhibitors have been used to separate the early, protein synthesis-independent (E-LTP) phase and the late, protein synthesis-dependent (L-LTP) phase. However, the role of these proteins has not been formally identified. Additionally, several reports failed to show an effect of protein synthesis inhibitors on LTP. In this review, a detailed analysis of extensive behavioral and electrophysiological data reveals that the presumed correspondence of LTP temporal phases to memory phases is neither experimentally nor theoretically consistent. Moreover, an overview of the time courses of E-LTP in hippocampal slices reveals a wide variability ranging from <1 h to more than 5 h. The existence of all these conflictual findings should lead to a new vision of LTP. We believe that the E-LTP vs. L-LTP distinction, established with protein synthesis inhibitor studies, reflects a false dichotomy. We suggest that the duration of LTP and its dependency on protein synthesis are related to the availability of a set of proteins at synapses and not to the de novo synthesis of plasticity-related proteins. This availability is determined by protein turnover kinetics, which is regulated by previous and ongoing electrical activities and by energy store availability.
Collapse
|
16
|
Calabrese F, Riva MA, Molteni R. Synaptic alterations associated with depression and schizophrenia: potential as a therapeutic target. Expert Opin Ther Targets 2016; 20:1195-207. [PMID: 27167520 DOI: 10.1080/14728222.2016.1188080] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
INTRODUCTION In recent years, the concept of 'synaptopathy' has been extended from neurodegenerative and neurological disorders to psychiatric diseases. According to this nascent line of research, disruption in synaptic structure and function acts as the main determinant of mental illness. Therefore, molecular systems and processes crucial for synaptic activity may represent promising therapeutic targets. AREAS COVERED We review data on synaptic structural alterations in depression and schizophrenia and on specific molecular systems and/or mechanisms important for the maintenance of proper synaptic function. Specifically, we examine the involvement of the neuroligin system, the local protein translation, and the neurotrophin BDNF by reviewing clinical and preclinical studies, with particular attention to results provided by using animal models based on the role of stress in psychiatric diseases. Finally, we also discuss the impact of pharmacological treatment on these molecular systems/mechanisms. EXPERT OPINION The relevance of synaptic dysfunctions in psychiatric diseases is undoubted and the potential to normalize, ameliorate, and shape such alterations by acting on molecular systems crucial to ensure synaptic function property is fascinating. However, future studies are required to elucidate several open issues.
Collapse
Affiliation(s)
- Francesca Calabrese
- a Dipartimento di Scienze Farmacologiche e Biomolecolari , Università degli Studi di Milano , Milan , Italy
| | - Marco A Riva
- a Dipartimento di Scienze Farmacologiche e Biomolecolari , Università degli Studi di Milano , Milan , Italy
| | - Raffaella Molteni
- a Dipartimento di Scienze Farmacologiche e Biomolecolari , Università degli Studi di Milano , Milan , Italy
| |
Collapse
|
17
|
Gogliotti RG, Senter RK, Rook JM, Ghoshal A, Zamorano R, Malosh C, Stauffer SR, Bridges TM, Bartolome JM, Daniels JS, Jones CK, Lindsley CW, Conn PJ, Niswender CM. mGlu5 positive allosteric modulation normalizes synaptic plasticity defects and motor phenotypes in a mouse model of Rett syndrome. Hum Mol Genet 2016; 25:1990-2004. [PMID: 26936821 PMCID: PMC5062588 DOI: 10.1093/hmg/ddw074] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 02/04/2016] [Accepted: 02/29/2016] [Indexed: 11/14/2022] Open
Abstract
Rett syndrome (RS) is a neurodevelopmental disorder that shares many symptomatic and pathological commonalities with idiopathic autism. Alterations in protein synthesis-dependent synaptic plasticity (PSDSP) are a hallmark of a number of syndromic forms of autism; in the present work, we explore the consequences of disruption and rescue of PSDSP in a mouse model of RS. We report that expression of a key regulator of synaptic protein synthesis, the metabotropic glutamate receptor 5 (mGlu5) protein, is significantly reduced in both the brains of RS model mice and in the motor cortex of human RS autopsy samples. Furthermore, we demonstrate that reduced mGlu5 expression correlates with attenuated DHPG-induced long-term depression in the hippocampus of RS model mice, and that administration of a novel mGlu5 positive allosteric modulator (PAM), termed VU0462807, can rescue synaptic plasticity defects. Additionally, treatment of Mecp2-deficient mice with VU0462807 improves motor performance (open-field behavior and gait dynamics), corrects repetitive clasping behavior, as well as normalizes cued fear-conditioning defects. Importantly, due to the rationale drug discovery approach used in its development, our novel mGlu5 PAM improves RS phenotypes and synaptic plasticity defects without evoking the overt adverse effects commonly associated with potentiation of mGlu5 signaling (i.e. seizures), or affecting cardiorespiratory defects in RS model mice. These findings provide strong support for the continued development of mGlu5 PAMs as potential therapeutic agents for use in RS, and, more broadly, for utility in idiopathic autism.
Collapse
Affiliation(s)
- Rocco G Gogliotti
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Rebecca K Senter
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jerri M Rook
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Ayan Ghoshal
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Rocio Zamorano
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Chrysa Malosh
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA, Department of Chemistry and
| | - Shaun R Stauffer
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA, Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA and
| | - Thomas M Bridges
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jose M Bartolome
- Neuroscience Medicinal Chemistry, Janssen Research and Development, Jarama 75A., Toledo 45007, Spain
| | - J Scott Daniels
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Carrie K Jones
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Craig W Lindsley
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA, Department of Chemistry and
| | - P Jeffrey Conn
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA, Vanderbilt Kennedy Center
| | - Colleen M Niswender
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA, Vanderbilt Kennedy Center,
| |
Collapse
|
18
|
Pen Y, Borovok N, Reichenstein M, Sheinin A, Michaelevski I. Membrane-tethered AKT kinase regulates basal synaptic transmission and early phase LTP expression by modulation of post-synaptic AMPA receptor level. Hippocampus 2016; 26:1149-67. [PMID: 27068236 DOI: 10.1002/hipo.22597] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/28/2016] [Indexed: 01/17/2023]
Abstract
The serine/threonine kinase AKT/PKB plays a fundamental role in a wide variety of neuronal functions, including neuronal cell development, axonal growth, and synaptic plasticity. Multiple evidence link AKT signaling pathways to regulation of late phase long-term synaptic plasticity, synaptogenesis, and spinogenesis, as well as long-term memory formation. Nevertheless, the downstream effectors mediating the effects of AKT on early phase long-term potentiation (eLTP) are currently unknown. Here we report that using different regimes of pharmacological activation and inhibition of AKT activity in acute hippocampal slices, we found that AKT regulates the post-synaptic expression of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA) receptors affecting solely the expression of eLTP, with no effect on its induction and maintenance. We further show that both maintenance of basal synaptic activity and expression of eLTP require plasma membrane tethering by activated AKT and that basal synaptic activity may be regulated via the direct effects of AKT1 on the expression level of post-synaptic AMPA receptors bypassing the canonical AKT signaling. Finally, we establish that eLTP expression requires the involvement of both the canonical AKT signaling pathways and the direct effect of AKT1 on AMPA receptor activity/expression in the post-synaptic membrane. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Y Pen
- Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv, Israel
| | - N Borovok
- Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv, Israel
| | - M Reichenstein
- Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv, Israel
| | - A Sheinin
- Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv, Israel
| | - I Michaelevski
- Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv, Israel
| |
Collapse
|
19
|
Milak MS, Proper CJ, Mulhern ST, Parter AL, Kegeles LS, Ogden RT, Mao X, Rodriguez CI, Oquendo MA, Suckow RF, Cooper TB, Keilp JC, Shungu DC, Mann JJ. A pilot in vivo proton magnetic resonance spectroscopy study of amino acid neurotransmitter response to ketamine treatment of major depressive disorder. Mol Psychiatry 2016; 21:320-7. [PMID: 26283639 PMCID: PMC4758914 DOI: 10.1038/mp.2015.83] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 01/29/2015] [Accepted: 03/09/2015] [Indexed: 12/11/2022]
Abstract
The N-methyl-D-aspartate receptor antagonist ketamine can improve major depressive disorder (MDD) within hours. To evaluate the putative role of glutamatergic and GABAergic systems in ketamine's antidepressant action, medial prefrontal cortical (mPFC) levels of glutamate+glutamine (Glx) and γ-aminobutyric acid (GABA) were measured before, during, and after ketamine administration using proton magnetic resonance spectroscopy. Ketamine (0.5 mg kg(-1) intravenously) was administered to 11 depressed patients with MDD. Glx and GABA mPFC responses were measured as ratios relative to unsuppressed voxel tissue water (W) successfully in 8/11 patients. Ten of 11 patients remitted (50% reduction in 24-item Hamilton Depression Rating Scale and total score ⩽10) within 230 min of commencing ketamine. mPFC Glx/W and GABA/W peaked at 37.8%±7.5% and 38.0%±9.1% above baseline in ~26 min. Mean areas under the curve for Glx/W (P=0.025) and GABA/W (P=0.005) increased and correlated (r=0.796; P=0.018). Clinical improvement correlated with 90-min norketamine concentration (df=6, r=-0.78, P=0.023), but no other measures.
Collapse
Affiliation(s)
- Matthew S. Milak
- Molecular Imaging and Neuropathology Division, Department of Psychiatry, Columbia University, College of Physicians and Surgeons
- New York State Psychiatric Institute, Weill Medical College of Cornell University
| | - Caitlin J. Proper
- Molecular Imaging and Neuropathology Division, Department of Psychiatry, Columbia University, College of Physicians and Surgeons
| | - Stephanie T. Mulhern
- Molecular Imaging and Neuropathology Division, Department of Psychiatry, Columbia University, College of Physicians and Surgeons
| | - Amy L. Parter
- Molecular Imaging and Neuropathology Division, Department of Psychiatry, Columbia University, College of Physicians and Surgeons
| | - Lawrence S. Kegeles
- Molecular Imaging and Neuropathology Division, Department of Psychiatry, Columbia University, College of Physicians and Surgeons
- New York State Psychiatric Institute, Weill Medical College of Cornell University
| | - R. Todd Ogden
- Molecular Imaging and Neuropathology Division, Department of Psychiatry, Columbia University, College of Physicians and Surgeons
- Department of Biostatistics, Columbia University, Mailman School of Public Health
- New York State Psychiatric Institute, Weill Medical College of Cornell University
| | - Xiangling Mao
- Department of Radiology, Weill Medical College of Cornell University
| | - Carolyn I. Rodriguez
- Molecular Imaging and Neuropathology Division, Department of Psychiatry, Columbia University, College of Physicians and Surgeons
- New York State Psychiatric Institute, Weill Medical College of Cornell University
| | - Maria A. Oquendo
- Molecular Imaging and Neuropathology Division, Department of Psychiatry, Columbia University, College of Physicians and Surgeons
- New York State Psychiatric Institute, Weill Medical College of Cornell University
| | - Raymond F. Suckow
- New York State Psychiatric Institute, Weill Medical College of Cornell University
- Analytical Psychopharmacology Laboratory, the Nathan S. Kline Institute for Psychiatric Research
| | - Thomas B. Cooper
- New York State Psychiatric Institute, Weill Medical College of Cornell University
- Analytical Psychopharmacology Laboratory, the Nathan S. Kline Institute for Psychiatric Research
| | - John C. Keilp
- Molecular Imaging and Neuropathology Division, Department of Psychiatry, Columbia University, College of Physicians and Surgeons
- New York State Psychiatric Institute, Weill Medical College of Cornell University
| | - Dikoma C. Shungu
- New York State Psychiatric Institute, Weill Medical College of Cornell University
- Department of Radiology, Weill Medical College of Cornell University
| | - J. John Mann
- Molecular Imaging and Neuropathology Division, Department of Psychiatry, Columbia University, College of Physicians and Surgeons
- Department of Radiology, Columbia University, College of Physicians and Surgeons
- New York State Psychiatric Institute, Weill Medical College of Cornell University
| |
Collapse
|
20
|
Abstract
The structural plasticity of dendritic spines is considered to be essential for various forms of synaptic plasticity, learning, and memory. The process is mediated by a complex signaling network consisting of numerous species of molecules. Furthermore, the spatiotemporal dynamics of the biochemical signaling are regulated in a complicated manner because of geometrical restrictions from the unique morphology of the dendritic branches and spines. Recent advances in optical techniques have enabled the exploration of the spatiotemporal aspects of the signal regulations in spines and dendrites and have provided many insights into the principle of the biochemical computation that underlies spine structural plasticity.
Collapse
Affiliation(s)
- Jun Nishiyama
- Max Planck Florida Institute for Neuroscience, One Max Planck Way, Jupiter, FL 33458, USA
| | - Ryohei Yasuda
- Max Planck Florida Institute for Neuroscience, One Max Planck Way, Jupiter, FL 33458, USA.
| |
Collapse
|
21
|
Rozas NS, Redell JB, Pita-Almenar JD, Mckenna J, Moore AN, Gambello MJ, Dash PK. Intrahippocampal glutamine administration inhibits mTORC1 signaling and impairs long-term memory. ACTA ACUST UNITED AC 2015; 22:239-46. [PMID: 25878136 PMCID: PMC4408772 DOI: 10.1101/lm.038265.115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 02/13/2015] [Indexed: 11/25/2022]
Abstract
The mechanistic Target of Rapamycin Complex 1 (mTORC1), a key regulator of protein synthesis and cellular growth, is also required for long-term memory formation. Stimulation of mTORC1 signaling is known to be dependent on the availability of energy and growth factors, as well as the presence of amino acids. In vitro studies using serum- and amino acid-starved cells have reported that glutamine addition can either stimulate or repress mTORC1 activity, depending on the particular experimental system that was used. However, these experiments do not directly address the effect of glutamine on mTORC1 activity under physiological conditions in nondeprived cells in vivo. We present experimental results indicating that intrahippocampal administration of glutamine to rats reduces mTORC1 activity. Moreover, post-training administration of glutamine impairs long-term spatial memory formation, while coadministration of glutamine with leucine had no influence on memory. Intracellular recordings in hippocampal slices showed that glutamine did not alter either excitatory or inhibitory synaptic activity, suggesting that the observed memory impairments may not result from conversion of glutamine to either glutamate or GABA. Taken together, these findings indicate that glutamine can decrease mTORC1 activity in the brain and may have implications for treatments of neurological diseases associated with high mTORC1 signaling.
Collapse
Affiliation(s)
- Natalia S Rozas
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, Texas 77225, USA
| | - John B Redell
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, Texas 77225, USA
| | - Juan D Pita-Almenar
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, Texas 77225, USA
| | - James Mckenna
- Department of Human Genetics, Emory University, Atlanta, Georgia 30322, USA
| | - Anthony N Moore
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, Texas 77225, USA
| | - Michael J Gambello
- Department of Human Genetics, Emory University, Atlanta, Georgia 30322, USA
| | - Pramod K Dash
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, Texas 77225, USA
| |
Collapse
|
22
|
Dong C, Vashisht A, Hegde AN. Proteasome regulates the mediators of cytoplasmic polyadenylation signaling during late-phase long-term potentiation. Neurosci Lett 2014; 583:199-204. [PMID: 25263789 DOI: 10.1016/j.neulet.2014.09.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 08/30/2014] [Accepted: 09/17/2014] [Indexed: 11/29/2022]
Abstract
The ubiquitin-proteasome pathway is essential for long-term synaptic plasticity, but its exact roles remain unclear. Previously we established that proteasome inhibition increased the early, induction part of late-phase long-term potentiation (L-LTP) but blocks the late, maintenance part. Our prior work also showed that the proteasome modulates components of the mammalian target of rapamycin pathway for translation. In this study, we tested the possible role of the proteasome in regulating the cytoplasmic polyadenylation signaling required for translation during L-LTP. We found that a polyadenylation inhibitor cordycepin diminishes the enhancement of early L-LTP mediated by proteasome inhibition. Furthermore, blocking Aurora-A kinase and calcium-calmodulin-dependent kinase II reduces the increase in early L-LTP brought about by proteasome inhibition. Our results suggest a link between polyadenylation-mediated translational control and protein degradation during induction of long-term synaptic plasticity.
Collapse
Affiliation(s)
- Chenghai Dong
- Department of Neurobiology and Anatomy, Wake Forest University Health Sciences Medical Center Boulevard, Winston-Salem, NC 27157, USA
| | - Anirudh Vashisht
- Department of Neurobiology and Anatomy, Wake Forest University Health Sciences Medical Center Boulevard, Winston-Salem, NC 27157, USA
| | - Ashok N Hegde
- Department of Neurobiology and Anatomy, Wake Forest University Health Sciences Medical Center Boulevard, Winston-Salem, NC 27157, USA.
| |
Collapse
|
23
|
Proteasome modulates positive and negative translational regulators in long-term synaptic plasticity. J Neurosci 2014; 34:3171-82. [PMID: 24573276 DOI: 10.1523/jneurosci.3291-13.2014] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Proteolysis by the ubiquitin-proteasome pathway appears to have a complex role in synaptic plasticity, but its various functions remain to be elucidated. Using late phase long-term potentiation (L-LTP) in the hippocampus of the mouse as a model for long-term synaptic plasticity, we previously showed that inhibition of the proteasome enhances induction but blocks maintenance of L-LTP. In this study, we investigated the possible mechanisms by which proteasome inhibition has opposite effects on L-LTP induction and maintenance. Our results show that inhibiting phosphatidyl inositol-3 kinase or blocking the interaction between eukaryotic initiation factors 4E (eIF4E) and 4G (eIF4G) reduces the enhancement of L-LTP induction brought about by proteasome inhibition suggesting interplay between proteolysis and the signaling pathway mediated by mammalian target of rapamycin (mTOR). Also, proteasome inhibition leads to accumulation of translational activators in the mTOR pathway such as eIF4E and eukaryotic elongation factor 1A (eEF1A) early during L-LTP causing increased induction. Furthermore, inhibition of the proteasome causes a buildup of translational repressors, such as polyadenylate-binding protein interacting protein 2 (Paip2) and eukaryotic initiation factor 4E-binding protein 2 (4E-BP2), during late stages of L-LTP contributing to the blockade of L-LTP maintenance. Thus, the proteasome plays a critical role in regulating protein synthesis during L-LTP by tightly controlling translation. Our results provide novel mechanistic insights into the interplay between protein degradation and protein synthesis in long-term synaptic plasticity.
Collapse
|
24
|
Lasarge CL, Danzer SC. Mechanisms regulating neuronal excitability and seizure development following mTOR pathway hyperactivation. Front Mol Neurosci 2014; 7:18. [PMID: 24672426 PMCID: PMC3953715 DOI: 10.3389/fnmol.2014.00018] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 02/27/2014] [Indexed: 01/19/2023] Open
Abstract
The phosphatidylinositol-3-kinase/phosphatase and tensin homolog (PTEN)-mammalian target of rapamycin (mTOR) pathway regulates a variety of neuronal functions, including cell proliferation, survival, growth, and plasticity. Dysregulation of the pathway is implicated in the development of both genetic and acquired epilepsies. Indeed, several causal mutations have been identified in patients with epilepsy, the most prominent of these being mutations in PTEN and tuberous sclerosis complexes 1 and 2 (TSC1, TSC2). These genes act as negative regulators of mTOR signaling, and mutations lead to hyperactivation of the pathway. Animal models deleting PTEN, TSC1, and TSC2 consistently produce epilepsy phenotypes, demonstrating that increased mTOR signaling can provoke neuronal hyperexcitability. Given the broad range of changes induced by altered mTOR signaling, however, the mechanisms underlying seizure development in these animals remain uncertain. In transgenic mice, cell populations with hyperactive mTOR have many structural abnormalities that support recurrent circuit formation, including somatic and dendritic hypertrophy, aberrant basal dendrites, and enlargement of axon tracts. At the functional level, mTOR hyperactivation is commonly, but not always, associated with enhanced synaptic transmission and plasticity. Moreover, these populations of abnormal neurons can affect the larger network, inducing secondary changes that may explain paradoxical findings reported between cell and network functioning in different models or at different developmental time points. Here, we review the animal literature examining the link between mTOR hyperactivation and epileptogenesis, emphasizing the impact of enhanced mTOR signaling on neuronal form and function.
Collapse
Affiliation(s)
- Candi L Lasarge
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center Cincinnati, OH, USA
| | - Steve C Danzer
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center Cincinnati, OH, USA ; Department of Anesthesia, University of Cincinnati Cincinnati, OH, USA ; Department of Pediatrics, University of Cincinnati Cincinnati, OH, USA
| |
Collapse
|
25
|
Schacher S, Hu JY. The less things change, the more they are different: contributions of long-term synaptic plasticity and homeostasis to memory. Learn Mem 2014; 21:128-34. [PMID: 24532836 PMCID: PMC3929853 DOI: 10.1101/lm.027326.112] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
An important cellular mechanism contributing to the strength and duration of memories is activity-dependent alterations in the strength of synaptic connections within the neural circuit encoding the memory. Reversal of the memory is typically correlated with a reversal of the cellular changes to levels expressed prior to the stimulation. Thus, for stimulus-induced changes in synapse strength and their reversals to be functionally relevant, cellular mechanisms must regulate and maintain synapse strength both prior to and after the stimuli inducing learning and memory. The strengths of synapses within a neural circuit at any given moment are determined by cellular and molecular processes initiated during development and those subsequently regulated by the history of direct activation of the neural circuit and system-wide stimuli such as stress or motivational state. The cumulative actions of stimuli and other factors on an already modified neural circuit are attenuated by homeostatic mechanisms that prevent changes in overall synaptic inputs and excitability above or below specific set points (synaptic scaling). The mechanisms mediating synaptic scaling prevent potential excitotoxic alterations in the circuit but also may attenuate additional cellular changes required for learning and memory, thereby apparently limiting information storage. What cellular and molecular processes control synaptic strengths before and after experience/activity and its reversals? In this review we will explore the synapse-, whole cell-, and circuit level-specific processes that contribute to an overall zero sum-like set of changes and long-term maintenance of synapse strengths as a consequence of the accommodative interactions between long-term synaptic plasticity and homeostasis.
Collapse
Affiliation(s)
- Samuel Schacher
- Department of Neuroscience, Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute, New York, New York 10032, USA
| | | |
Collapse
|
26
|
Gururajan A, van den Buuse M. Is the mTOR-signalling cascade disrupted in Schizophrenia? J Neurochem 2013; 129:377-87. [PMID: 24266366 DOI: 10.1111/jnc.12622] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 11/07/2013] [Accepted: 11/10/2013] [Indexed: 02/01/2023]
Abstract
The mammalian target of rapamycin (mTOR) signalling cascade is involved in the intracellular regulation of protein synthesis, specifically for proteins involved in controlling neuronal morphology and facilitating synaptic plasticity. Research has revealed that the activity of the mTOR cascade is influenced by several extracellular and environmental factors that have been implicated in schizophrenia. Therefore, there is reason to believe that one of the downstream consequences of dysfunction or hypofunction of these factors in schizophrenia is disrupted mTOR signalling and hence impaired protein synthesis. This results in abnormal neurodevelopment and deficient synaptic plasticity, outcomes which could underlie some of the positive, negative and cognitive symptoms of schizophrenia. This review will discuss the functional roles of the mTOR cascade and present evidence in support of a novel mTOR-based hypothesis of the neuropathology of schizophrenia. During neurodevelopment, genetic and epigenetic factors can disrupt mTOR signalling which affects synthesis of proteins essential for correct neuronal growth and network connectivity. This renders the CNS particularly vulnerable to the effects of secondary factors during adolescence which increases the risk of developing schizophrenia in adulthood. This review discusses the functional roles of the mTOR cascade and presents evidence in support of a novel mTOR-based hypothesis of the neuropathology of schizophrenia. Testing this hypothesis will advance our understanding of the aetiology of this illness and reveal novel therapeutic targets.
Collapse
Affiliation(s)
- Anand Gururajan
- Behavioural Neuroscience Laboratory, The Florey Institute of Neuroscience & Mental Health, Parkville, Vic., Australia
| | | |
Collapse
|
27
|
Lyu D, Yu W, Tang N, Wang R, Zhao Z, Xie F, He Y, Du H, Chen J. The mTOR signaling pathway regulates pain-related synaptic plasticity in rat entorhinal-hippocampal pathways. Mol Pain 2013; 9:64. [PMID: 24313960 PMCID: PMC3892125 DOI: 10.1186/1744-8069-9-64] [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] [Received: 08/13/2013] [Accepted: 11/22/2013] [Indexed: 01/01/2023] Open
Abstract
Background Our previous work demonstrated that persistent peripheral nociception (PPN) leads to synaptic plasticity and functional changes in the rat hippocampus. The protein kinase mTOR is a critical regulator of protein synthesis-dependent synaptic plasticity in the hippocampus as well as synaptic plasticity associated with central and peripheral pain sensitization. We examined the role of mTOR signaling in pain-associated entorhinal cortex (EC) - hippocampal synaptic plasticity to reveal possible cellular mechanisms underlying the effects of chronic pain on cognition and emotion. Results Subcutaneous injection of bee venom (BV) into one hind paw to induce PPN resulted in sustained (> 8 h) mTOR phospho-activation and enhanced phosphorylation of the mTOR target p70 S6 kinase (S6K) in the hippocampus. The magnitude and duration of long-term potentiation (LTP) in both EC - dentate gyrus (DG) and EC - CA1 synaptic pathways were elevated in BV-treated rats as measured by microelectrode array recording. Moreover, the number of potentiated synapses in the hippocampus was markedly upregulated by BV-induced PPN. Both elevated mTOR-S6K signaling and enhanced LTP induced by BV injection were reversed by systemic injection of the mTOR inhibitor rapamycin (RAPA). Rats injected with BV exhibited markedly reduced ambulation and exploratory activity in the open field (signs of depression and anxiety) compared to controls, and these effects were also reversed by RAPA. Conclusion We suggest that PPN-induced enhancement of synaptic plasticity in EC - hippocampal pathways and the behavioral effects of PPN are dependent on mTOR-S6K signaling.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Hongyin Du
- Department of Anesthesiology, Tianjin First Center Hospital, TianJin 300192, China.
| | | |
Collapse
|
28
|
Kudryashova IV. Analysis of conditions that are important for the beginning of consolidation in a model of long-term synaptic potentiation. NEUROCHEM J+ 2013. [DOI: 10.1134/s1819712413030070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
29
|
BDNF-dependent recycling facilitates TrkB translocation to postsynaptic density during LTP via a Rab11-dependent pathway. J Neurosci 2013; 33:9214-30. [PMID: 23699532 DOI: 10.1523/jneurosci.3256-12.2013] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) plays an important role in the activity-dependent regulation of synaptic structure and function via tropomyosin related kinase B (TrkB) receptor activation. However, whether BDNF could regulate TrkB levels at synapse during long-term potentiation (LTP) is still unknown. We show in cultured rat hippocampal neurons that chemical LTP (cLTP) stimuli selectively promote endocytic recycling of BDNF-dependent full-length TrkB (TrkB-FL) receptors, but not isoform T1 (TrkB.T1) receptors, via a Rab11-dependent pathway. Moreover, neuronal-activity-enhanced TrkB-FL recycling could facilitate receptor translocation to postsynaptic density and enhance BDNF-induced extracellular signal-regulated kinase and phosphatidylinositol 3-kinase activation and rat hippocampal neuron survival. Finally, we found that cLTP could stimulate the switch of Rab11 from an inactive to an active form and that GTP-bound Rab11 could enhance the interaction between TrkB-FL and PSD-95. Therefore, the recycling endosome could serve as a reserve pool to supply TrkB-FL receptors for LTP maintenance. These findings provide a mechanistic link between Rab11-dependent endocytic recycling and TrkB modulation of synaptic plasticity.
Collapse
|
30
|
Abstract
Long-term synaptic plasticity involves changes in the expression and membrane insertion of cell-surface proteins. Interestingly, the mRNAs encoding many cell-surface proteins are localized to dendrites, but whether dendritic protein synthesis is required for activity-induced surface expression of specific proteins is unknown. Herein, we used microfluidic devices to demonstrate that dendritic protein synthesis is necessary for activity-induced insertion of GluN2A-containing NMDA receptors in rat hippocampal neurons. Furthermore, visualization of activity-induced local translation of GluN2A mRNA and membrane insertion of GluN2A protein in dendrites was directly observed and shown to depend on a 3' untranslated region cytoplasmic polyadenylation element and its associated translation complex. These findings uncover a novel mechanism for cytoplasmic polyadenylation element-mediated posttranscriptional regulation of GluN2A mRNA to control NMDA receptor surface expression during synaptic plasticity.
Collapse
|
31
|
Gafford GM, Parsons RG, Helmstetter FJ. Memory accuracy predicts hippocampal mTOR pathway activation following retrieval of contextual fear memory. Hippocampus 2013; 23:842-7. [PMID: 23640842 DOI: 10.1002/hipo.22140] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 04/07/2013] [Accepted: 04/16/2013] [Indexed: 11/08/2022]
Abstract
Prior work suggests that hippocampus-dependent memory undergoes a systems consolidation process such that recent memories are stored in the hippocampus, while older memories are independent of the hippocampus and instead dependent on cortical areas. One problem with interpreting these studies is that memory for the contextual stimuli weakens as time passes between the training event and testing and older memories are often less detailed, making it difficult to determine if memory storage in the hippocampus is related to the age or to the accuracy of the memory. Activity of the mammalian target of rapamycin (mTOR) signaling pathway is known to be important for controlling protein translation necessary for both memory consolidation after initial learning and for the reconsolidation of memory after retrieval. We tested whether p70s6 kinase (p70s6K), a key component of the mTOR signaling pathway, is activated following retrieval of context fear memory in the dorsal hippocampus (DH) and anterior cingulate cortex (ACC) at 1, 10, or 36 days after context fear conditioning. We also tested whether strengthening memory for the contextual stimuli changed p70s6K phosphorylation in these structures 36 days after training. We show that under standard training conditions retrieval of a recently formed memory is initially precise and involves the DH. Over time it loses detail, becomes independent of the DH and depends on the ACC. In a subsequent experiment, we preserved the accuracy of older memories through pre-exposure to the training context. We show that remote memory still involved the DH in animals given pre-exposure. These data support the notion that detailed memories depend on the DH regardless of their age.
Collapse
Affiliation(s)
- Georgette M Gafford
- Psychology Department, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | | | | |
Collapse
|
32
|
Swanger SA, Bassell GJ. Dendritic protein synthesis in the normal and diseased brain. Neuroscience 2012; 232:106-27. [PMID: 23262237 DOI: 10.1016/j.neuroscience.2012.12.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 11/21/2012] [Accepted: 12/01/2012] [Indexed: 01/25/2023]
Abstract
Synaptic activity is a spatially limited process that requires a precise, yet dynamic, complement of proteins within the synaptic micro-domain. The maintenance and regulation of these synaptic proteins is regulated, in part, by local mRNA translation in dendrites. Protein synthesis within the postsynaptic compartment allows neurons tight spatial and temporal control of synaptic protein expression, which is critical for proper functioning of synapses and neural circuits. In this review, we discuss the identity of proteins synthesized within dendrites, the receptor-mediated mechanisms regulating their synthesis, and the possible roles for these locally synthesized proteins. We also explore how our current understanding of dendritic protein synthesis in the hippocampus can be applied to new brain regions and to understanding the pathological mechanisms underlying varied neurological diseases.
Collapse
Affiliation(s)
- S A Swanger
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - G J Bassell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA.
| |
Collapse
|
33
|
Wang J, Meng F, Cottrell JE, Sacktor TC, Kass IS. Metabotropic actions of the volatile anaesthetic sevoflurane increase protein kinase M synthesis and induce immediate preconditioning protection of rat hippocampal slices. J Physiol 2012; 590:4093-107. [PMID: 22674720 DOI: 10.1113/jphysiol.2012.233965] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Anaesthetic preconditioning occurs when a volatile anaesthetic, such as sevoflurane, is administered before a hypoxic or ischaemic insult; this has been shown to improve neuronal recovery after the insult. We found that sevoflurane-induced preconditioning in the rat hippocampal slice enhances the hypoxic hyperpolarization of CA1 pyramidal neurons, delays and attenuates their hypoxic depolarization, and increases the number of neurons that recover their resting and action potentials after hypoxia. These altered electrophysiological effects and the improved recovery corresponded with an increase in the amount of a constitutively active, atypical protein kinase C isoform found in brain, protein kinase M zeta (PKMζ). A selective inhibitor of this kinase, zeta inhibitory peptide (ZIP), blocked the increase in the total amount of PKMζ protein and the amount of the activated form of this kinase, phospho-PKMζ (p-PKMζ); it also blocked the altered electrophysiological effects and the improved recovery. We found that both cycloheximide, a general protein synthesis inhibitor, and rapamycin, a selective inhibitor of the mTOR pathway for regulating protein synthesis, blocked the increase in p-PKMζ, the electrophysiological changes, and the improved recovery due to sevoflurane-induced preconditioning. Glibenclamide, a KATP channel blocker, when present only during the hypoxia, prevented the enhanced hyperpolarization, the delayed and attenuated hypoxic depolarization, and the improved recovery following sevoflurane-induced preconditioning. To examine the function of persistent PKMζ and KATP channel activity after the preconditioning was established, we administered 4% sevoflurane for 30 min and then discontinued it for 30 min before 10 min of hypoxia. When either tolbutamide, a KATP channel blocker, or ZIP were administered at least 15 min after the washout of sevoflurane, there was little recovery compared with sevoflurane alone. Thus, continuous KATP channel and PKMζ activity are required to maintain preconditioning protection. We conclude that sevoflurane induces activation of the mTOR pathway, increasing the new protein synthesis of PKMζ, which is constitutively phosphorylated to its active form, leading to an increased KATP channel-induced hyperpolarizaton. This hyperpolarization delays and attenuates the hypoxic depolarization, improving the recovery of neurons following hypoxia. Thus, sevoflurane acts via a metabotropic pathway to improve recovery following hypoxia.
Collapse
Affiliation(s)
- Jun Wang
- Department of Anesthesiology, Box 6, State University of New York Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, USA
| | | | | | | | | |
Collapse
|
34
|
Bhakar AL, Dölen G, Bear MF. The pathophysiology of fragile X (and what it teaches us about synapses). Annu Rev Neurosci 2012; 35:417-43. [PMID: 22483044 DOI: 10.1146/annurev-neuro-060909-153138] [Citation(s) in RCA: 279] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Fragile X is the most common known inherited cause of intellectual disability and autism, and it typically results from transcriptional silencing of FMR1 and loss of the encoded protein, FMRP (fragile X mental retardation protein). FMRP is an mRNA-binding protein that functions at many synapses to inhibit local translation stimulated by metabotropic glutamate receptors (mGluRs) 1 and 5. Recent studies on the biology of FMRP and the signaling pathways downstream of mGluR1/5 have yielded deeper insight into how synaptic protein synthesis and plasticity are regulated by experience. This new knowledge has also suggested ways that altered signaling and synaptic function can be corrected in fragile X, and human clinical trials based on this information are under way.
Collapse
Affiliation(s)
- Asha L Bhakar
- Howard Hughes Medical Institute, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
| | | | | |
Collapse
|
35
|
Trabalza A, Colazingari S, Sgobio C, Bevilacqua A. Contextual learning increases dendrite complexity and EphrinB2 levels in hippocampal mouse neurons. Behav Brain Res 2011; 227:175-83. [PMID: 22101302 DOI: 10.1016/j.bbr.2011.11.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 11/03/2011] [Accepted: 11/06/2011] [Indexed: 10/15/2022]
Abstract
Although the role of hippocampus in memory processing is well assessed, an association of experience-dependent behavioural modifications with hippocampal neuron morphological and biochemical changes deserves further characterisation. Here, we present evidence of dendritic alterations together with rapid accumulation of EphrinB2, a factor known to influence cell plasticity, in pyramidal neurons of the CA1 area of mouse hippocampus, during the formation of recent contextual fear memory. Male C57BL/6N mice exhibited a robust fear response 24h after contextual and cued fear conditioning. At this time and in the absence of the memory test, conditioned mice showed morphological alterations in hippocampal and lateral amygdala neurons. Western blot analysis of extracts from conditioned but not pseudoconditioned or naive mice showed a specific increase in the amount of EphrinB2 in the hippocampus but not the cortex. However, levels of EphA4 receptor, known to interact trans-synaptically with EphrinB2, did not change upon conditioning in extracts from the same structures. Finally, immunohistochemical analysis of the hippocampus and amygdala of conditioned mice showed increased levels of EphrinB2 in pyramidal neurons of the CA1 area, when compared to pseudoconditioned and control mice. Such increase was not observed in other hippocampal areas or the amygdala. These results suggest that rapid accumulation of EphrinB2 in hippocampal CA1 neurons is involved in the behavioural and cellular modifications induced by contextual fear conditioning. A similar mechanism does not appear to occur in lateral amygdala neurons, in spite of the robust behavioural and cellular modifications induced in such structure by cued fear conditioning.
Collapse
Affiliation(s)
- Antonio Trabalza
- Department of Psychology, Section of Neuroscience, University of Rome "Sapienza", via dei Marsi 78, 00185 Rome, Italy
| | | | | | | |
Collapse
|
36
|
Disrupting function of FK506-binding protein 1b/12.6 induces the Ca²+-dysregulation aging phenotype in hippocampal neurons. J Neurosci 2011; 31:1693-703. [PMID: 21289178 DOI: 10.1523/jneurosci.4805-10.2011] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
With aging, multiple Ca(2+)-associated electrophysiological processes exhibit increased magnitude in hippocampal pyramidal neurons, including the Ca(2+)-dependent slow afterhyperpolarization (sAHP), L-type voltage-gated Ca(2+) channel (L-VGCC) activity, Ca(2+)-induced Ca(2+) release (CICR) from ryanodine receptors (RyRs), and Ca(2+) transients. This pattern of Ca(2+) dysregulation correlates with reduced neuronal excitability/plasticity and impaired learning/memory and has been proposed to contribute to unhealthy brain aging and Alzheimer's disease. However, little is known about the underlying molecular mechanisms. In cardiomyocytes, FK506-binding protein 1b/12.6 (FKBP1b) binds and stabilizes RyR2 in the closed state, inhibiting RyR-mediated Ca(2+) release. Moreover, we recently found that hippocampal Fkbp1b expression is downregulated, whereas Ryr2 and Frap1/Mtor (mammalian target of rapamycin) expression is upregulated with aging in rats. Here, we tested the hypothesis that disrupting FKBP1b function also destabilizes Ca(2+) homeostasis in hippocampal neurons and is sufficient to induce the aging phenotype of Ca(2+) dysregulation in young animals. Selective knockdown of Fkbp1b with interfering RNA in vitro (96 h) enhanced voltage-gated Ca(2+) current in cultured neurons, whereas in vivo Fkbp1b knockdown by microinjection of viral vector (3-4 weeks) dramatically increased the sAHP in hippocampal slice neurons from young-adult rats. Rapamycin, which displaces FKBP1b from RyRs in myocytes, similarly enhanced VGCC current and the sAHP and also increased CICR. Moreover, FKBP1b knockdown in vivo was associated with upregulation of RyR2 and mTOR protein expression. Thus, disruption of FKBP1b recapitulated much of the Ca(2+)-dysregulation aging phenotype in young rat hippocampus, supporting a novel hypothesis that declining FKBP function plays a major role in unhealthy brain aging.
Collapse
|
37
|
Navakkode S, Sajikumar S, Sacktor TC, Frey JU. Protein kinase Mzeta is essential for the induction and maintenance of dopamine-induced long-term potentiation in apical CA1 dendrites. Learn Mem 2010; 17:605-11. [PMID: 21084457 DOI: 10.1101/lm.1991910] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Dopaminergic D1/D5-receptor-mediated processes are important for certain forms of memory as well as for a cellular model of memory, hippocampal long-term potentiation (LTP) in the CA1 region of the hippocampus. D1/D5-receptor function is required for the induction of the protein synthesis-dependent maintenance of CA1-LTP (L-LTP) through activation of the cAMP/PKA-pathway. In earlier studies we had reported a synergistic interaction of D1/D5-receptor function and N-methyl-D-aspartate (NMDA)-receptors for L-LTP. Furthermore, we have found the requirement of the atypical protein kinase C isoform, protein kinase Mζ (PKMζ) for conventional electrically induced L-LTP, in which PKMζ has been identified as a LTP-specific plasticity-related protein (PRP) in apical CA1-dendrites. Here, we investigated whether the dopaminergic pathway activates PKMζ. We found that application of dopamine (DA) evokes a protein synthesis-dependent LTP that requires synergistic NMDA-receptor activation and protein synthesis in apical CA1-dendrites. We identified PKMζ as a DA-induced PRP, which exerted its action at activated synaptic inputs by processes of synaptic tagging.
Collapse
Affiliation(s)
- Sheeja Navakkode
- Department of Neurophysiology, Leibniz-Institute for Neurobiology, Brenneckestrasse 6, 39118 Magdeburg, Germany
| | | | | | | |
Collapse
|
38
|
Cajigas IJ, Will T, Schuman EM. Protein homeostasis and synaptic plasticity. EMBO J 2010; 29:2746-52. [PMID: 20717144 DOI: 10.1038/emboj.2010.173] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Accepted: 07/02/2010] [Indexed: 12/20/2022] Open
Abstract
It is clear that de novo protein synthesis has an important function in synaptic transmission and plasticity. A substantial amount of work has shown that mRNA translation in the hippocampus is spatially controlled and that dendritic protein synthesis is required for different forms of long-term synaptic plasticity. More recently, several studies have highlighted a function for protein degradation by the ubiquitin proteasome system in synaptic plasticity. These observations suggest that changes in synaptic transmission involve extensive regulation of the synaptic proteome. Here, we review experimental data supporting the idea that protein homeostasis is a regulatory motif for synaptic plasticity.
Collapse
Affiliation(s)
- Iván J Cajigas
- Department of Synaptic Plasticity, Max Planck Institute for Brain Research, Frankfurt am Main, Germany
| | | | | |
Collapse
|
39
|
Garelick MG, Kennedy BK. TOR on the brain. Exp Gerontol 2010; 46:155-63. [PMID: 20849946 DOI: 10.1016/j.exger.2010.08.030] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 08/20/2010] [Accepted: 08/27/2010] [Indexed: 11/19/2022]
Abstract
Signaling by target of rapamycin (mTOR in mammals) has been shown to modulate lifespan in several model organisms ranging from yeast to mice. In mice, reduced mTOR signaling by chronic rapamycin treatment leads to life span extension, raising the possibility that rapamycin and its analogs may benefit the aging brain and serve as effective treatments of age-related neurodegenerative diseases. Here, we review mTOR signaling and how neurons utilize mTOR to regulate brain function, including regulation of feeding, synaptic plasticity and memory formation. Additionally, we discuss recent findings that evaluate the mechanisms by which reduced mTOR activity might benefit the aging brain in normal and pathological states. We will focus on recent studies investigating mTOR and Alzheimer's disease, Parkinson's disease, and polyglutamine expansion syndromes such as Huntington's disease.
Collapse
Affiliation(s)
- Michael G Garelick
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | | |
Collapse
|
40
|
Traynelis SF, Wollmuth LP, McBain CJ, Menniti FS, Vance KM, Ogden KK, Hansen KB, Yuan H, Myers SJ, Dingledine R. Glutamate receptor ion channels: structure, regulation, and function. Pharmacol Rev 2010; 62:405-96. [PMID: 20716669 PMCID: PMC2964903 DOI: 10.1124/pr.109.002451] [Citation(s) in RCA: 2579] [Impact Index Per Article: 184.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The mammalian ionotropic glutamate receptor family encodes 18 gene products that coassemble to form ligand-gated ion channels containing an agonist recognition site, a transmembrane ion permeation pathway, and gating elements that couple agonist-induced conformational changes to the opening or closing of the permeation pore. Glutamate receptors mediate fast excitatory synaptic transmission in the central nervous system and are localized on neuronal and non-neuronal cells. These receptors regulate a broad spectrum of processes in the brain, spinal cord, retina, and peripheral nervous system. Glutamate receptors are postulated to play important roles in numerous neurological diseases and have attracted intense scrutiny. The description of glutamate receptor structure, including its transmembrane elements, reveals a complex assembly of multiple semiautonomous extracellular domains linked to a pore-forming element with striking resemblance to an inverted potassium channel. In this review we discuss International Union of Basic and Clinical Pharmacology glutamate receptor nomenclature, structure, assembly, accessory subunits, interacting proteins, gene expression and translation, post-translational modifications, agonist and antagonist pharmacology, allosteric modulation, mechanisms of gating and permeation, roles in normal physiological function, as well as the potential therapeutic use of pharmacological agents acting at glutamate receptors.
Collapse
Affiliation(s)
- Stephen F Traynelis
- Department of Pharmacology, Emory University School of Medicine, Rollins Research Center, 1510 Clifton Road, Atlanta, GA 30322-3090, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Li L, Xu B, Zhu Y, Chen L, Sokabe M, Chen L. DHEA prevents Aβ25-35-impaired survival of newborn neurons in the dentate gyrus through a modulation of PI3K-Akt-mTOR signaling. Neuropharmacology 2010; 59:323-33. [PMID: 20167228 DOI: 10.1016/j.neuropharm.2010.02.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Revised: 02/03/2010] [Accepted: 02/09/2010] [Indexed: 11/25/2022]
Abstract
Infusion (i.c.v.) of beta-amyloid 25-35 (Abeta(25-35)) stimulates proliferation of progenitor cells in the hippocampal dentate gyrus (DG) of adult male mice, but a large population of the newborn cells will die in the 2nd week after birth, a critical period for neurite growth. Neurosteroid dehydroepiandrosterone (DHEA) has been demonstrated to promote neurite growth. Herein, we report that the DHEA-treatment on 6-12 days after BrdU-injection (BrdU-D(6-12)) dose-dependently attenuates the loss of newborn neurons induced by Abeta(25-35)-infusion. The DHEA-neuroprotection was blocked by the sigma(1) receptor antagonist NE100 and mimicked by the sigma(1) receptor agonist PRE084 when administered on BrdU-D(6-12). The DHEA-action was sensitive to the PI3K inhibitor LY294002 and the mammalian target of rapamycin (mTOR) inhibitor rapamycin. The Abeta(25-35)-infusion decreased the levels of Akt, mTOR and p70S6k phosphorylation, which could be rescued by DHEA-treatment in a sigma(1) receptor-dependent manner. Furthermore, the Abeta(25-35)-infusion led to a decrease in the dendritic density and length of doublecortin positive cells in the DG, which also was improved by the DHEA-treatment on BrdU-D(6-12). These findings suggest that DHEA prevents the Abeta(25-35)-impaired survival and dendritic growth of newborn neurons through a sigma(1) receptor-mediated modulation of PI3K-Akt-mTOR-p70S6k signaling.
Collapse
Affiliation(s)
- Liang Li
- Department of Physiology, Nanjing Medical University, Jiangsu, China
| | | | | | | | | | | |
Collapse
|
42
|
Moon IS, Cho SJ, Seog DH, Walikonis R. Neuronal activation increases the density of eukaryotic translation initiation factor 4E mRNA clusters in dendrites of cultured hippocampal neurons. Exp Mol Med 2009; 41:601-10. [PMID: 19381064 DOI: 10.3858/emm.2009.41.8.066] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Activity-dependent dendritic translation in CNS neurons is important for the synapse-specific provision of proteins that may be necessary for strengthening of synaptic connections. A major rate-limiting factor during protein synthesis is the availability of eukaryotic translation initiation factor 4E (eIF4E), an mRNA 5-cap-binding protein. In this study we show by fluorescence in situ hybridization (FISH) that the mRNA for eIF4E is present in the dendrites of cultured rat hippocampal neurons. Under basal culture conditions, 58.7 +/-11.6% of the eIF4E mRNA clusters localize with or immediately adjacent to PSD-95 clusters. Neuronal activation with KCl (60 mM, 10 min) very significantly increases the number of eIF4E mRNA clusters in dendrites by 50.1 and 74.5% at 2 and 6 h after treatment, respectively. In addition, the proportion of eIF4E mRNA clusters that localize with PSD-95 increases to 74.4+/-7.7% and 77.8+/-7.6% of the eIF4E clusters at 2 and 6 h after KCl treatment, respectively. Our results demonstrate the presence of eIF4E mRNA in dendrites and an activity-dependent increase of these clusters at synaptic sites. This provides a potential mechanism by which protein translation at synapses may be enhanced in response to synaptic stimulation.
Collapse
Affiliation(s)
- Il Soo Moon
- Department of Anatomy, College of Medicine, Dongguk University, Gyeongju 780-714, Korea
| | | | | | | |
Collapse
|
43
|
Chen TJ, Wang DC, Chen SS. Amyloid-beta interrupts the PI3K-Akt-mTOR signaling pathway that could be involved in brain-derived neurotrophic factor-induced Arc expression in rat cortical neurons. J Neurosci Res 2009; 87:2297-307. [PMID: 19301428 DOI: 10.1002/jnr.22057] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The deposition of amyloid-beta (Abeta) contributes to the pathogenesis of Alzheimer's disease. Even at low levels, Abeta may interfere with various signaling cascades critical for the synaptic plasticity that underlies learning and memory. Brain-derived neurotrophic factor (BDNF) is well known to be capable of inducing the synthesis of activity-regulated cytoskeleton-associated protein (Arc), which plays a fundamental role in modulating synaptic plasticity. Our recent study has demonstrated that treatment of fibrillar Abeta at a nonlethal level was sufficient to impair BDNF-induced Arc expression in cultured rat cortical neurons. In this study, BDNF treatment alone induced the activation of the phosphatidylinositol 3-kinase-Akt-mammlian target of rapamycin (PI3K-Akt-mTOR) signaling pathway, the phosphorylation of eukaryotic initiation factor 4E binding protein (4EBP1) and p70 ribosomal S6 kinase (p70S6K), the dephosphorylation of eukaryotic elongation factor 2 (eEF2), and the expression of Arc. Interrupting the PI3K-Akt-mTOR signaling pathway by inhibitors prevented the effects of BDNF, indicating the involvement of this pathway in BDNF-induced 4EBP1 phosphorylation, p70S6K phosphorylation, eEF2 dephosphorylation, and Arc expression. Nonlethal Abeta pretreatment partially blocked these effects of BDNF. Double- immunofluorescent staining in rat cortical neurons further confirmed the coexistence of eEF2 dephosphorylation and Arc expression following BDNF treatment regardless of the presence of Abeta. These results reveal that, in cultured rat cortical neurons, Abeta interrupts the PI3K-Akt-mTOR signaling pathway that could be involved in BDNF-induced Arc expression. Moreover, this study also provides the first evidence that there is a close correlation between BDNF-induced eEF2 dephosphorylation and BDNF-induced Arc expression. (c) 2009 Wiley-Liss, Inc.
Collapse
Affiliation(s)
- Tsan-Ju Chen
- Department of Physiology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
| | | | | |
Collapse
|
44
|
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: 722] [Impact Index Per Article: 48.1] [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.
Collapse
Affiliation(s)
- Mauro Costa-Mattioli
- Department of Biochemistry and McGill Cancer Center, McGill University, Montreal QCH3G1Y6, Canada.
| | | | | | | |
Collapse
|
45
|
Sánchez-Carbente MDR, Desgroseillers L. Understanding the importance of mRNA transport in memory. PROGRESS IN BRAIN RESEARCH 2008; 169:41-58. [PMID: 18394467 DOI: 10.1016/s0079-6123(07)00003-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
RNA localization is an important mechanism to sort proteins to specific subcellular domains. In neurons, several mRNAs are localized in dendrites and their presence allows autonomous control of local translation in response to stimulation of specific synapses. Active constitutive and activity-induced mechanisms of mRNA transport have been described that represent critical steps in the establishment and maintenance of synaptic plasticity. In recent years, the molecular composition of different transporting units has been reported and the identification of proteins and mRNAs in these RNA granules contributes to our understanding of the key steps that regulate mRNA transport and translation. Although RNA granules are heterogeneous, several proteins are common to different RNA granule populations, suggesting that they play important roles in the formation of the granules and/or their regulation during transport and translation. About 1-4% of the neuron transcriptome is found in RNA granules and the characterization of bound mRNAs reveal that they encode proteins of the cytoskeleton, the translation machinery, vesicle trafficking, and/or proteins involved in synaptic plasticity. Non-coding RNAs and microRNAs are also found in dendrites and likely regulate RNA translation. These mechanisms of mRNA transport and local translation are critical for synaptic plasticity mediated by activity or experience and memory.
Collapse
|
46
|
Activation of exchange protein activated by cyclic-AMP enhances long-lasting synaptic potentiation in the hippocampus. Learn Mem 2008; 15:403-11. [PMID: 18509114 DOI: 10.1101/lm.830008] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
cAMP is a critical second messenger implicated in synaptic plasticity and memory in the mammalian brain. Substantial evidence links increases in intracellular cAMP to activation of cAMP-dependent protein kinase (PKA) and subsequent phosphorylation of downstream effectors (transcription factors, receptors, protein kinases) necessary for long-term potentiation (LTP) of synaptic strength. However, cAMP may also initiate signaling via a guanine nucleotide exchange protein directly activated by cAMP (Epac). The role of Epac in hippocampal synaptic plasticity is unknown. We found that in area CA1 of mouse hippocampal slices, activation of Epac enhances maintenance of LTP without affecting basal synaptic transmission. The persistence of this form of LTP requires extracellular signal-regulated protein kinase (ERK) and new protein synthesis, but not transcription. Because ERK is involved in translational control of long-lasting plasticity and memory, our data suggest that Epac is a crucial link between cAMP and ERK during some forms of protein synthesis-dependent LTP. Activation of Epac represents a novel signaling pathway for rapid regulation of the stability of enduring forms of LTP and, perhaps, of hippocampus- dependent long-term memories.
Collapse
|
47
|
Dong C, Upadhya SC, Ding L, Smith TK, Hegde AN. Proteasome inhibition enhances the induction and impairs the maintenance of late-phase long-term potentiation. Learn Mem 2008; 15:335-47. [PMID: 18441292 PMCID: PMC2364605 DOI: 10.1101/lm.984508] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 03/20/2008] [Indexed: 01/21/2023]
Abstract
Protein degradation by the ubiquitin-proteasome pathway plays important roles in synaptic plasticity, but the molecular mechanisms by which proteolysis regulates synaptic strength are not well understood. We investigated the role of the proteasome in hippocampal late-phase long-term potentiation (L-LTP), a model for enduring synaptic plasticity. We show here that inhibition of the proteasome enhances the induction of L-LTP, but inhibits its maintenance. Proteasome inhibitor-mediated enhancement of the early part of L-LTP requires activation of NMDA receptors and the cAMP-dependent protein kinase. Augmentation of L-LTP induction by proteasome inhibition is blocked by a protein synthesis inhibitor anisomycin and is sensitive to the drug rapamycin. Our findings indicate that proteasome inhibition increases the induction of L-LTP by stabilizing locally translated proteins in dendrites. In addition, our data show that inhibition of the proteasome blocks transcription of brain-derived neurotrophic factor (BDNF), which is a cAMP-responsive element-binding protein (CREB)-inducible gene. Furthermore, our results demonstrate that the proteasome inhibitors block degradation of ATF4, a CREB repressor. Thus, proteasome inhibition appears to hinder CREB-mediated transcription. Our results indicate that blockade of proteasome activity obstructs the maintenance of L-LTP by interfering with transcription as well as translation required to sustain L-LTP. Thus, proteasome-mediated proteolysis has different roles during the induction and the maintenance of L-LTP.
Collapse
Affiliation(s)
- Chenghai Dong
- Department of Neurobiology and Anatomy, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157, USA
| | - Sudarshan C. Upadhya
- Department of Neurobiology and Anatomy, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157, USA
| | - Lan Ding
- Department of Neurobiology and Anatomy, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157, USA
| | - Thuy K. Smith
- Department of Neurobiology and Anatomy, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157, USA
| | - Ashok N. Hegde
- Department of Neurobiology and Anatomy, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157, USA
| |
Collapse
|
48
|
Antion MD, Merhav M, Hoeffer CA, Reis G, Kozma SC, Thomas G, Schuman EM, Rosenblum K, Klann E. Removal of S6K1 and S6K2 leads to divergent alterations in learning, memory, and synaptic plasticity. Learn Mem 2008; 15:29-38. [PMID: 18174371 DOI: 10.1101/lm.661908] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protein synthesis is required for the expression of enduring memories and long-lasting synaptic plasticity. During cellular proliferation and growth, S6 kinases (S6Ks) are activated and coordinate the synthesis of de novo proteins. We hypothesized that protein synthesis mediated by S6Ks is critical for the manifestation of learning, memory, and synaptic plasticity. We have tested this hypothesis with genetically engineered mice deficient for either S6K1 or S6K2. We have found that S6K1-deficient mice express an early-onset contextual fear memory deficit within one hour of training, a deficit in conditioned taste aversion (CTA), impaired Morris water maze acquisition, and hypoactive exploratory behavior. In contrast, S6K2-deficient mice exhibit decreased contextual fear memory seven days after training, a reduction in latent inhibition of CTA, and normal spatial learning in the Morris water maze. Surprisingly, neither S6K1- nor S6K2-deficient mice exhibited alterations in protein synthesis-dependent late-phase long-term potentiation (L-LTP). However, removal of S6K1, but not S6K2, compromised early-phase LTP expression. Furthermore, we observed that S6K1-deficient mice have elevated basal levels of Akt phosphorylation, which is further elevated following induction of L-LTP. Taken together, our findings demonstrate that removal of S6K1 leads to a distinct array of behavioral and synaptic plasticity phenotypes that are not mirrored by the removal of S6K2. Our observations suggest that neither gene by itself is required for L-LTP but instead may be required for other types of synaptic plasticity required for cognitive processing.
Collapse
Affiliation(s)
- Marcia D Antion
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
49
|
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]
|
50
|
Sacktor TC. Chapter 2 PKMζ, LTP maintenance, and the dynamic molecular biology of memory storage. PROGRESS IN BRAIN RESEARCH 2008; 169:27-40. [DOI: 10.1016/s0079-6123(07)00002-7] [Citation(s) in RCA: 166] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
|