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Desch K, Langer JD, Schuman EM. Dynamic bi-directional phosphorylation events associated with the reciprocal regulation of synapses during homeostatic up- and down-scaling. Cell Rep 2021; 36:109583. [PMID: 34433048 PMCID: PMC8411114 DOI: 10.1016/j.celrep.2021.109583] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 06/15/2021] [Accepted: 07/29/2021] [Indexed: 01/17/2023] Open
Abstract
Homeostatic synaptic scaling allows for bi-directional adjustment of the strength of synaptic connections in response to changes in their input. Protein phosphorylation modulates many neuronal processes, but it has not been studied on a global scale during synaptic scaling. Here, we use liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses to measure changes in the phosphoproteome in response to up- or down-scaling in cultured cortical neurons over minutes to 24 h. Of ~45,000 phosphorylation events, ~3,300 (associated with 1,285 phosphoproteins) are regulated by homeostatic scaling. Activity-sensitive phosphoproteins are predominantly located at synapses and involved in cytoskeletal reorganization. We identify many early phosphorylation events that could serve as sensors for the activity offset as well as late and/or persistent phosphoregulation that could represent effector mechanisms driving the homeostatic response. Much of the persistent phosphorylation is reciprocally regulated by up- or down-scaling, suggesting that mechanisms underlying these two poles of synaptic regulation make use of a common signaling axis. Global proteome and phosphoproteome dynamics following homeostatic synaptic scaling Approximately 3,300 activity-sensitive, synapse-associated phospho-events Persistent signaling of ~25% of initial phospho-events (min to 24 h) Persistent and reciprocal phosphoregulation links synaptic up- and down-scaling
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Affiliation(s)
- Kristina Desch
- Max Planck Institute for Brain Research, Max von Laue Strasse 4, 60438 Frankfurt, Germany
| | - Julian D Langer
- Max Planck Institute for Brain Research, Max von Laue Strasse 4, 60438 Frankfurt, Germany.
| | - Erin M Schuman
- Max Planck Institute for Brain Research, Max von Laue Strasse 4, 60438 Frankfurt, Germany.
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2
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Dysregulation of peripheral expression of the YWHA genes during conversion to psychosis. Sci Rep 2020; 10:9863. [PMID: 32555255 PMCID: PMC7299951 DOI: 10.1038/s41598-020-66901-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 05/04/2020] [Indexed: 12/01/2022] Open
Abstract
The seven human 14-3-3 proteins are encoded by the YWHA-gene family. They are expressed in the brain where they play multiple roles including the modulation of synaptic plasticity and neuronal development. Previous studies have provided arguments for their involvement in schizophrenia, but their role during disease onset is unknown. We explored the peripheral-blood expression level of the seven YWHA genes in 92 young individuals at ultra-high risk for psychosis (UHR). During the study, 36 participants converted to psychosis (converters) while 56 did not (non-converters). YWHA genes expression was evaluated at baseline and after a mean follow-up of 10.3 months using multiplex quantitative PCR. Compared with non-converters, the converters had a significantly higher baseline expression levels for 5 YWHA family genes, and significantly different longitudinal changes in the expression of YWHAE, YWHAG, YWHAH, YWHAS and YWAHZ. A principal-component analysis also indicated that the YWHA expression was significantly different between converters and non-converters suggesting a dysregulation of the YWHA co-expression network. Although these results were obtained from peripheral blood which indirectly reflects brain chemistry, they indicate that this gene family may play a role in psychosis onset, opening the way to the identification of prognostic biomarkers or new drug targets.
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Yang JW, Wang XR, Zhang M, Xiao LY, Zhu W, Ji CS, Liu CZ. Acupuncture as a multifunctional neuroprotective therapy ameliorates cognitive impairment in a rat model of vascular dementia: A quantitative iTRAQ proteomics study. CNS Neurosci Ther 2018; 24:1264-1274. [PMID: 30278105 DOI: 10.1111/cns.13063] [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: 12/20/2017] [Revised: 07/31/2018] [Accepted: 08/24/2018] [Indexed: 12/20/2022] Open
Abstract
AIMS Acupuncture has been reported to affect vascular dementia through a variety of molecular mechanisms. An isobaric tag for relative and absolute quantification (iTRAQ) with high-resolution liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses makes it possible to attain a global profile of proteins. Hence, we used an iTRAQ-LC-MS/MS strategy to unravel the underlying mechanism of acupuncture. METHODS Wistar rats were subjected to vascular dementia with bilateral common carotid occlusion. Acupuncture was intervened for 2 weeks at 3 days after surgery. The Morris water maze was used to assess the cognitive function. Proteins were screened by quantitative proteomics and analyzed by bioinformatic analysis. Four differentially expressed proteins (DEPs) were validated by western blot. The reactive oxygen species (ROS) production, neuron cell loss, and long-term potentiation (LTP) were determined after western blot. RESULTS Acupuncture at proper acupoints significantly improved cognitive function. A total of 31 proteins were considered DEPs. Gene ontology (GO) analysis showed that most of the DEPs were related to oxidative stress, apoptosis, and synaptic function, which were regarded as the major cellular processes related to acupuncture effect. Western blot results confirm the credibility of iTRAQ results. Acupuncture could decrease ROS production, increase neural cell survival, and improve LTP, which verified the three major cellular processes. CONCLUSION Acupuncture may serve as a promising clinical candidate for the treatment of vascular dementia via regulating oxidative stress, apoptosis, or synaptic functions.
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Affiliation(s)
- Jing-Wen Yang
- Department of Acupuncture and Moxibustion, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China.,School of Acupuncture-Moxibution and Tuina, Beijing University of Chinese Medicine, Beijing, China
| | - Xue-Rui Wang
- Beijing Hospital of Traditional Chinese Medicine affiliated to Capital Medical University, Beijing, China
| | - Meng Zhang
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Ling-Yong Xiao
- Department of Acupuncture and Moxibustion, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Wen Zhu
- Department of Acupuncture and Moxibustion, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Cai-Shuo Ji
- Department of Acupuncture and Moxibustion, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Cun-Zhi Liu
- Department of Acupuncture and Moxibustion, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
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4
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14-3-3 Proteins in Glutamatergic Synapses. Neural Plast 2018; 2018:8407609. [PMID: 29849571 PMCID: PMC5937437 DOI: 10.1155/2018/8407609] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 03/13/2018] [Accepted: 03/27/2018] [Indexed: 11/18/2022] Open
Abstract
The 14-3-3 proteins are a family of proteins that are highly expressed in the brain and particularly enriched at synapses. Evidence accumulated in the last two decades has implicated 14-3-3 proteins as an important regulator of synaptic transmission and plasticity. Here, we will review previous and more recent research that has helped us understand the roles of 14-3-3 proteins at glutamatergic synapses. A key challenge for the future is to delineate the 14-3-3-dependent molecular pathways involved in regulating synaptic functions.
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5
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Changes in Brain 14-3-3 Proteins in Response to Insulin Resistance Induced by a High Palatable Diet. Mol Neurobiol 2014; 52:710-8. [PMID: 25280668 DOI: 10.1007/s12035-014-8905-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Accepted: 09/24/2014] [Indexed: 01/16/2023]
Abstract
The 14-3-3 protein family takes part in a wide range of cellular processes and is expressed in all eukaryotic organisms. In mammals, seven isoforms (β, ε, η, γ, τ, ζ, and σ) have been identified. 14-3-3 proteins are suggested to modulate the insulin-signaling cascade in the brain. The aim of this study was to investigate whether insulin resistance state induced by high palatable diet modulates expression of the 14-3-3 proteins in brain. Wistar male rats (n = 8) were divided into two experimental groups: insulin resistant (IR), induced by high palatable diet, and control (CO) group. Biochemical parameters (glucose tolerance test and plasma lipid profile) were evaluated after 130 days. Brain structures (cortex and hippocampus) were dissected for evaluation of messenger RNA (mRNA) and protein levels of different 14-3-3 proteins. Statistical analyses included Student t test and Pearson correlation. Significant decrease was observed in Ywhah and in Ywahq mRNA levels in the cortex of IR group, while no changes were observed in the hippocampus. Significant increase of θ isoform was observed in hippocampus IR group by immunodetection, while no differences were detected in the remaining isoforms. Inverse correlation was observed between blood glucose levels in cortex IR group and both Ywhah and Ywhaq mRNA levels. Protein levels of Creb and phosphatidylinositide 3-kinases (PI3K) showed to be increased in the hippocampus. These alterations may be due to a compensatory effect of impaired insulin signaling. We demonstrated differential expression of 14-3-3 isoforms throughout brain regions of rats with IR. As a whole, our results indicate that brain 14-3-3 levels are influenced by different diets.
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14-3-3 proteins are required for hippocampal long-term potentiation and associative learning and memory. J Neurosci 2014; 34:4801-8. [PMID: 24695700 DOI: 10.1523/jneurosci.4393-13.2014] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
14-3-3 is a family of regulatory proteins highly expressed in the brain. Previous invertebrate studies have demonstrated the importance of 14-3-3 in the regulation of synaptic functions and learning and memory. However, the in vivo role of 14-3-3 in these processes has not been determined using mammalian animal models. Here, we report the behavioral and electrophysiological characterization of a new animal model of 14-3-3 proteins. These transgenic mice, considered to be a 14-3-3 functional knock-out, express a known 14-3-3 inhibitor in various brain regions of different founder lines. We identify a founder-specific impairment in hippocampal-dependent learning and memory tasks, as well as a correlated suppression in long-term synaptic plasticity of the hippocampal synapses. Moreover, hippocampal synaptic NMDA receptor levels are selectively reduced in the transgenic founder line that exhibits both behavioral and synaptic plasticity deficits. Collectively, our findings provide evidence that 14-3-3 is a positive regulator of associative learning and memory at both the behavioral and cellular level.
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Federighi G, Traina G, Macchi M, Ciampini C, Bernardi R, Baldi E, Bucherelli C, Brunelli M, Scuri R. Modulation of gene expression in contextual fear conditioning in the rat. PLoS One 2013; 8:e80037. [PMID: 24278235 PMCID: PMC3837011 DOI: 10.1371/journal.pone.0080037] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 09/27/2013] [Indexed: 01/30/2023] Open
Abstract
In contextual fear conditioning (CFC) a single training leads to long-term memory of context-aversive electrical foot-shocks association. Mid-temporal regions of the brain of trained and naive rats were obtained 2 days after conditioning and screened by two-directional suppression subtractive hybridization. A pool of differentially expressed genes was identified and some of them were randomly selected and confirmed with qRT-PCR assay. These transcripts showed high homology for rat gene sequences coding for proteins involved in different cellular processes. The expression of the selected transcripts was also tested in rats which had freely explored the experimental apparatus (exploration) and in rats to which the same number of aversive shocks had been administered in the same apparatus, but temporally compressed so as to make the association between painful stimuli and the apparatus difficult (shock-only). Some genes resulted differentially expressed only in the rats subjected to CFC, others only in exploration or shock-only rats, whereas the gene coding for translocase of outer mitochondrial membrane 20 protein and nardilysin were differentially expressed in both CFC and exploration rats. For example, the expression of stathmin 1 whose transcripts resulted up regulated was also tested to evaluate the transduction and protein localization after conditioning.
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Affiliation(s)
- Giuseppe Federighi
- Dipartimento di Ricerca Traslazionale e Delle Nuove Tecnologie in Medicina e Chirurgia, Unità di Fisiologia, Università di Pisa, Pisa, Italy
| | - Giovanna Traina
- Dipartimento di Scienze Economico-Estimative e degli Alimenti, Sezione di Chimica Bromatologica, Biochimica, Fisiologia e Nutrizione, Università degli Studi di Perugia, Perugia, Italy
| | - Monica Macchi
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy
| | - Cristina Ciampini
- Dipartimento di Ricerca Traslazionale e Delle Nuove Tecnologie in Medicina e Chirurgia, Unità di Fisiologia, Università di Pisa, Pisa, Italy
| | - Rodolfo Bernardi
- Dipartimento di Scienze Agrarie, Genetica Alimentari e Agro-Ambientali, Università di Pisa, Pisa, Italy
| | - Elisabetta Baldi
- Dipartimento di Scienze Fisiologiche, Università di Firenze, Firenze, Italy
| | - Corrado Bucherelli
- Dipartimento di Scienze Fisiologiche, Università di Firenze, Firenze, Italy
| | | | - Rossana Scuri
- Dipartimento di Ricerca Traslazionale e Delle Nuove Tecnologie in Medicina e Chirurgia, Unità di Fisiologia, Università di Pisa, Pisa, Italy
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8
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Yang Y, Calakos N. Presynaptic long-term plasticity. Front Synaptic Neurosci 2013; 5:8. [PMID: 24146648 PMCID: PMC3797957 DOI: 10.3389/fnsyn.2013.00008] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 09/09/2013] [Indexed: 01/01/2023] Open
Abstract
Long-term synaptic plasticity is a major cellular substrate for learning, memory, and behavioral adaptation. Although early examples of long-term synaptic plasticity described a mechanism by which postsynaptic signal transduction was potentiated, it is now apparent that there is a vast array of mechanisms for long-term synaptic plasticity that involve modifications to either or both the presynaptic terminal and postsynaptic site. In this article, we discuss current and evolving approaches to identify presynaptic mechanisms as well as discuss their limitations. We next provide examples of the diverse circuits in which presynaptic forms of long-term synaptic plasticity have been described and discuss the potential contribution this form of plasticity might add to circuit function. Finally, we examine the present evidence for the molecular pathways and cellular events underlying presynaptic long-term synaptic plasticity.
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Affiliation(s)
- Ying Yang
- Department of Pediatrics, Stanford University School of Medicine Stanford, CA, USA
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9
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Ferrero JJ, Alvarez AM, Ramírez-Franco J, Godino MC, Bartolomé-Martín D, Aguado C, Torres M, Luján R, Ciruela F, Sánchez-Prieto J. β-Adrenergic receptors activate exchange protein directly activated by cAMP (Epac), translocate Munc13-1, and enhance the Rab3A-RIM1α interaction to potentiate glutamate release at cerebrocortical nerve terminals. J Biol Chem 2013; 288:31370-85. [PMID: 24036110 DOI: 10.1074/jbc.m113.463877] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The adenylyl cyclase activator forskolin facilitates synaptic transmission presynaptically via cAMP-dependent protein kinase (PKA). In addition, cAMP also increases glutamate release via PKA-independent mechanisms, although the downstream presynaptic targets remain largely unknown. Here, we describe the isolation of a PKA-independent component of glutamate release in cerebrocortical nerve terminals after blocking Na(+) channels with tetrodotoxin. We found that 8-pCPT-2'-O-Me-cAMP, a specific activator of the exchange protein directly activated by cAMP (Epac), mimicked and occluded forskolin-induced potentiation of glutamate release. This Epac-mediated increase in glutamate release was dependent on phospholipase C, and it increased the hydrolysis of phosphatidylinositol 4,5-bisphosphate. Moreover, the potentiation of glutamate release by Epac was independent of protein kinase C, although it was attenuated by the diacylglycerol-binding site antagonist calphostin C. Epac activation translocated the active zone protein Munc13-1 from soluble to particulate fractions; it increased the association between Rab3A and RIM1α and redistributed synaptic vesicles closer to the presynaptic membrane. Furthermore, these responses were mimicked by the β-adrenergic receptor (βAR) agonist isoproterenol, consistent with the immunoelectron microscopy and immunocytochemical data demonstrating presynaptic expression of βARs in a subset of glutamatergic synapses in the cerebral cortex. Based on these findings, we conclude that βARs couple to a cAMP/Epac/PLC/Munc13/Rab3/RIM-dependent pathway to enhance glutamate release at cerebrocortical nerve terminals.
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Affiliation(s)
- Jose J Ferrero
- From the Departamento de Bioquímica, Facultad de Veterinaria, Universidad Complutense, 28040 Madrid, Spain
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10
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Sun C, Qiao H, Zhou Q, Wang Y, Wu Y, Zhou Y, Li Y. Modulation of GluK2a subunit-containing kainate receptors by 14-3-3 proteins. J Biol Chem 2013; 288:24676-90. [PMID: 23861400 PMCID: PMC3750165 DOI: 10.1074/jbc.m113.462069] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 07/11/2013] [Indexed: 11/06/2022] Open
Abstract
Kainate receptors (KARs) are one of the ionotropic glutamate receptors that mediate excitatory postsynaptic currents (EPSCs) with characteristically slow kinetics. Although mechanisms for the slow kinetics of KAR-EPSCs are not totally understood, recent evidence has implicated a regulatory role of KAR-associated proteins. Here, we report that decay kinetics of GluK2a-containing receptors is modulated by closely associated 14-3-3 proteins. 14-3-3 binding requires PKC-dependent phosphorylation of serine residues localized in the carboxyl tail of the GluK2a subunit. In transfected cells, 14-3-3 binding to GluK2a slows desensitization kinetics of both homomeric GluK2a and heteromeric GluK2a/GluK5 receptors. Moreover, KAR-EPSCs at mossy fiber-CA3 synapses decay significantly faster in the 14-3-3 functional knock-out mice. Collectively, these results demonstrate that 14-3-3 proteins are an important regulator of GluK2a-containing KARs and may contribute to the slow decay kinetics of native KAR-EPSCs.
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Affiliation(s)
- Changcheng Sun
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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11
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Schröder MS, Stellmacher A, Romorini S, Marini C, Montenegro-Venegas C, Altrock WD, Gundelfinger ED, Fejtova A. Regulation of presynaptic anchoring of the scaffold protein Bassoon by phosphorylation-dependent interaction with 14-3-3 adaptor proteins. PLoS One 2013; 8:e58814. [PMID: 23516560 PMCID: PMC3597591 DOI: 10.1371/journal.pone.0058814] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 02/07/2013] [Indexed: 01/10/2023] Open
Abstract
The proper organization of the presynaptic cytomatrix at the active zone is essential for reliable neurotransmitter release from neurons. Despite of the virtual stability of this tightly interconnected proteinaceous network it becomes increasingly clear that regulated dynamic changes of its composition play an important role in the processes of synaptic plasticity. Bassoon, a core component of the presynaptic cytomatrix, is a key player in structural organization and functional regulation of presynaptic release sites. It is one of the most highly phosphorylated synaptic proteins. Nevertheless, to date our knowledge about functions mediated by any one of the identified phosphorylation sites of Bassoon is sparse. In this study, we have identified an interaction of Bassoon with the small adaptor protein 14-3-3, which depends on phosphorylation of the 14-3-3 binding motif of Bassoon. In vitro phosphorylation assays indicate that phosphorylation of the critical Ser-2845 residue of Bassoon can be mediated by a member of the 90-kDa ribosomal S6 protein kinase family. Elimination of Ser-2845 from the 14-3-3 binding motif results in a significant decrease of Bassoon's molecular exchange rates at synapses of living rat neurons. We propose that the phosphorylation-induced 14-3-3 binding to Bassoon modulates its anchoring to the presynaptic cytomatrix. This regulation mechanism might participate in molecular and structural presynaptic remodeling during synaptic plasticity.
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Affiliation(s)
- Markus S. Schröder
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Anne Stellmacher
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Stefano Romorini
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Claudia Marini
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | | | - Wilko D. Altrock
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Center for Behavioral Brain Science, Magdeburg, Germany
| | - Eckart D. Gundelfinger
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Center for Behavioral Brain Science, Magdeburg, Germany
- * E-mail: (EDG); (AF)
| | - Anna Fejtova
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- * E-mail: (EDG); (AF)
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Gandini MA, Felix R. Functional interactions between voltage-gated Ca(2+) channels and Rab3-interacting molecules (RIMs): new insights into stimulus-secretion coupling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:551-8. [PMID: 22198390 DOI: 10.1016/j.bbamem.2011.12.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 12/08/2011] [Accepted: 12/09/2011] [Indexed: 12/27/2022]
Abstract
Stimulus-secretion coupling is a complex set of intracellular reactions initiated by an external stimulus that result in the release of hormones and neurotransmitters. Under physiological conditions this signaling process takes a few milliseconds, and to minimize delays cells have developed a formidable integrated network, in which the relevant molecules are tightly packed on the nanometer scale. Active zones, the sites of release, are composed of several different proteins including voltage-gated Ca(2+) (Ca(V)) channels. It is well acknowledged that hormone and neurotransmitter release is initiated by the activation of these channels located close to docked vesicles, though the mechanisms that enrich channels at release sites are largely unknown. Interestingly, Rab3 binding proteins (RIMs), a diverse multidomain family of proteins that operate as effectors of the small G protein Rab3 involved in secretory vesicle trafficking, have recently identified as binding partners of Ca(V) channels, placing both proteins in the center of an interaction network in the molecular anatomy of the active zones that influence different aspects of secretion. Here, we review recent evidences providing support for the notion that RIMs directly bind to the pore-forming and auxiliary β subunits of Ca(V) channels and with RIM-binding protein, another interactor of the channels. Through these interactions, RIMs regulate the biophysical properties of the channels and their anchoring relative to active zones, significantly influencing hormone and neurotransmitter release.
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Affiliation(s)
- María A Gandini
- Department of Cell Biology, National Polytechnic Institute, Mexico City, Mexico
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Koseki N, Kitaoka Y, Munemasa Y, Kumai T, Kojima K, Ueno S, Ohtani-Kaneko R. 17β-estradiol prevents reduction of retinal phosphorylated 14-3-3 zeta protein levels following a neurotoxic insult. Brain Res 2011; 1433:145-52. [PMID: 22154405 DOI: 10.1016/j.brainres.2011.11.034] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 10/17/2011] [Accepted: 11/14/2011] [Indexed: 11/26/2022]
Abstract
Previous studies demonstrated the substantial protective role of 17β-estradiol (E2) in several types of neuron, although its mechanism of action remains to be elucidated. In this study, we found that the levels of 14-3-3 zeta mRNA and phosphorylated and total 14-3-3 zeta proteins were significantly decreased in the rat retina after intravitreal injection of N-methyl-d-aspartate (NMDA). 17β-E2 implantation significantly inhibited NMDA-induced decreases in phosphorylated but not in total 14-3-3 zeta protein levels in the retina. There was a decrease in both phosphorylated and total 14-3-3 protein levels in RGC-5 cells, a retinal ganglion cell line, after glutamate and buthionine sulfoximine (BSO) exposure, and 17β-E2 treatment significantly inhibited only the decrease in phosphorylated but not in total 14-3-3 zeta protein levels. The cell viability assay showed substantial cell death after glutamate and BSO exposure and that 17β-E2 treatment significantly protects against this cell death. 17β-E2 treatment also significantly increased the level of phosphorylated 14-3-3 protein in RGC-5 cells without other treatments. These results suggest that a decrease in 14-3-3 zeta expression may be associated with retinal neurotoxicity induced by NMDA or the combination of glutamate and BSO. The regulation of 14-3-3 zeta phosphorylation is one possible mechanism of the protective effect of 17β-E2 in the retina.
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Affiliation(s)
- Natsuko Koseki
- Department of Life Sciences, Toyo University, Oura, Gunma, Japan
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14
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14-3-3 proteins in neurodegeneration. Semin Cell Dev Biol 2011; 22:696-704. [PMID: 21920445 DOI: 10.1016/j.semcdb.2011.08.005] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 08/11/2011] [Indexed: 11/23/2022]
Abstract
Among the first reported functions of 14-3-3 proteins was the regulation of tyrosine hydroxylase (TH) activity suggesting a possible involvement of 14-3-3 proteins in Parkinson's disease. Since then the relevance of 14-3-3 proteins in the pathogenesis of chronic as well as acute neurodegenerative diseases, including Alzheimer's disease, polyglutamine diseases, amyotrophic lateral sclerosis and stroke has been recognized. The reported function of 14-3-3 proteins in this context are as diverse as the mechanism involved in neurodegeneration, reaching from basal cellular processes like apoptosis, over involvement in features common to many neurodegenerative diseases, like protein stabilization and aggregation, to very specific processes responsible for the selective vulnerability of cellular populations in single neurodegenerative diseases. Here, we review what is currently known of the function of 14-3-3 proteins in nervous tissue focussing on the properties of 14-3-3 proteins important in neurodegenerative disease pathogenesis.
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Upadhya SC, Smith TK, Brennan PA, Mychaleckyj JC, Hegde AN. Expression profiling reveals differential gene induction underlying specific and non-specific memory for pheromones in mice. Neurochem Int 2011; 59:787-803. [PMID: 21884744 DOI: 10.1016/j.neuint.2011.08.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 07/11/2011] [Accepted: 08/08/2011] [Indexed: 01/06/2023]
Abstract
Memory for the mating male's pheromones in female mice is thought to require synaptic changes in the accessory olfactory bulb (AOB). Induction of this memory depends on release of glutamate in response to pheromonal exposure coincident with release of norepinephrine (NE) in the AOB following mating. A similar memory for pheromones can also be induced artificially by local infusion of the GABA(A) receptor antagonist bicuculline into the AOB. The natural memory formed by exposure to pheromones during mating is specific to the pheromones sensed by the female during mating. In contrast, the artificial memory induced by bicuculline is non-specific and results in the female mice recognizing all pheromones as if they were from the mating male. Although protein synthesis has been shown to be essential for development of pheromone memory, the gene expression cascades critical for memory formation are not known. We investigated changes in gene expression in the AOB using oligonucleotide microarrays during mating-induced pheromone memory (MIPM) as well as bicuculline-induced pheromone memory (BIPM). We found the set of genes induced during MIPM and BIPM are largely non-overlapping and Ingenuity Pathway Analysis revealed that the signaling pathways in MIPM and BIPM also differ. The products of genes induced during MIPM are associated with synaptic function, indicating the possibility of modification at specific synapses, while those induced during BIPM appear to possess neuron-wide functions, which would be consistent with global cellular changes. Thus, these results begin to provide a mechanistic explanation for specific and non-specific memories induced by pheromones and bicuculline infusion respectively.
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Affiliation(s)
- Sudarshan C Upadhya
- Department of Neurobiology and Anatomy, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA
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16
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Vernes SC, Oliver PL, Spiteri E, Lockstone HE, Puliyadi R, Taylor JM, Ho J, Mombereau C, Brewer A, Lowy E, Nicod J, Groszer M, Baban D, Sahgal N, Cazier JB, Ragoussis J, Davies KE, Geschwind DH, Fisher SE. Foxp2 regulates gene networks implicated in neurite outgrowth in the developing brain. PLoS Genet 2011; 7:e1002145. [PMID: 21765815 PMCID: PMC3131290 DOI: 10.1371/journal.pgen.1002145] [Citation(s) in RCA: 193] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 05/07/2011] [Indexed: 11/19/2022] Open
Abstract
Forkhead-box protein P2 is a transcription factor that has been associated with intriguing aspects of cognitive function in humans, non-human mammals, and song-learning birds. Heterozygous mutations of the human FOXP2 gene cause a monogenic speech and language disorder. Reduced functional dosage of the mouse version (Foxp2) causes deficient cortico-striatal synaptic plasticity and impairs motor-skill learning. Moreover, the songbird orthologue appears critically important for vocal learning. Across diverse vertebrate species, this well-conserved transcription factor is highly expressed in the developing and adult central nervous system. Very little is known about the mechanisms regulated by Foxp2 during brain development. We used an integrated functional genomics strategy to robustly define Foxp2-dependent pathways, both direct and indirect targets, in the embryonic brain. Specifically, we performed genome-wide in vivo ChIP-chip screens for Foxp2-binding and thereby identified a set of 264 high-confidence neural targets under strict, empirically derived significance thresholds. The findings, coupled to expression profiling and in situ hybridization of brain tissue from wild-type and mutant mouse embryos, strongly highlighted gene networks linked to neurite development. We followed up our genomics data with functional experiments, showing that Foxp2 impacts on neurite outgrowth in primary neurons and in neuronal cell models. Our data indicate that Foxp2 modulates neuronal network formation, by directly and indirectly regulating mRNAs involved in the development and plasticity of neuronal connections.
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Affiliation(s)
- Sonja C. Vernes
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter L. Oliver
- Medical Research Council Functional Genetics Unit, University of Oxford, Oxford, United Kingdom
| | - Elizabeth Spiteri
- Program in Neurogenetics, Department of Neurology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Helen E. Lockstone
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Rathi Puliyadi
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Jennifer M. Taylor
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Joses Ho
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Cedric Mombereau
- INSERM Institute du Fer à Moulin, University Pierre and Marie Curie, UMR-S 839, Paris, France
| | - Ariel Brewer
- INSERM Institute du Fer à Moulin, University Pierre and Marie Curie, UMR-S 839, Paris, France
| | - Ernesto Lowy
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Jérôme Nicod
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Matthias Groszer
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- INSERM Institute du Fer à Moulin, University Pierre and Marie Curie, UMR-S 839, Paris, France
| | - Dilair Baban
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Natasha Sahgal
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Jean-Baptiste Cazier
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Jiannis Ragoussis
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Kay E. Davies
- Medical Research Council Functional Genetics Unit, University of Oxford, Oxford, United Kingdom
| | - Daniel H. Geschwind
- Program in Neurogenetics, Department of Neurology, University of California Los Angeles, Los Angeles, California, United States of America
- Semel Institute and Department of Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Simon E. Fisher
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Language and Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
- * E-mail:
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Wagner W, McCroskery S, Hammer JA. An efficient method for the long-term and specific expression of exogenous cDNAs in cultured Purkinje neurons. J Neurosci Methods 2011; 200:95-105. [PMID: 21708190 DOI: 10.1016/j.jneumeth.2011.06.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 06/13/2011] [Indexed: 01/10/2023]
Abstract
We present a simple and efficient method for expressing cDNAs in Purkinje neurons (PNs) present in heterogeneous mouse cerebellar cultures. The method combines the transfection of freshly dissociated cerebellar cells via nucleofection with the use of novel expression plasmids containing a fragment of the L7 (Pcp2) gene that, within the cerebellum, drives PN-specific expression. The efficiency of PN transfection (determined 13 days post nucleofection) is approximately 70%. Double and triple transfections are routinely achieved at slightly lower efficiencies. Expression in PNs is obvious after one week in culture and still strong after three weeks, by which time these neurons are well-developed. Moreover, high-level expression is restricted almost exclusively to the PNs present in these mixed cultures, which greatly facilitates the characterization of PN-specific functions. As proof of principle, we used this method to visualize (1) the morphology of living PNs expressing mGFP, (2) the localization and dynamics of the dendritic spine proteins PSD-93 and Homer-3a tagged with mGFP and (3) the interaction of live PNs expressing mGFP with other cerebellar neurons expressing mCherry from a β-Actin promoter plasmid. Finally, we created a series of L7-plasmids containing different fluorescent protein cDNAs that are suited for the expression of cDNAs of interest as N- and C-terminally tagged fluorescent fusion proteins. In summary, this procedure allows for the highly efficient, long-term, and specific expression of multiple cDNAs in differentiated PNs, and provides a favorable alternative to two procedures (viral transduction, ballistic gene delivery) used previously to express genes in cultured PNs.
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Affiliation(s)
- Wolfgang Wagner
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Ramser EM, Wolters G, Dityateva G, Dityatev A, Schachner M, Tilling T. The 14-3-3ζ protein binds to the cell adhesion molecule L1, promotes L1 phosphorylation by CKII and influences L1-dependent neurite outgrowth. PLoS One 2010; 5:e13462. [PMID: 20976158 PMCID: PMC2956685 DOI: 10.1371/journal.pone.0013462] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Accepted: 09/24/2010] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The cell adhesion molecule L1 is crucial for mammalian nervous system development. L1 acts as a mediator of signaling events through its intracellular domain, which comprises a putative binding site for 14-3-3 proteins. These regulators of diverse cellular processes are abundant in the brain and preferentially expressed by neurons. In this study, we investigated whether L1 interacts with 14-3-3 proteins, how this interaction is mediated, and whether 14-3-3 proteins influence the function of L1. METHODOLOGY/PRINCIPAL FINDINGS By immunoprecipitation, we demonstrated that 14-3-3 proteins are associated with L1 in mouse brain. The site of 14-3-3 interaction in the L1 intracellular domain (L1ICD), which was identified by site-directed mutagenesis and direct binding assays, is phosphorylated by casein kinase II (CKII), and CKII phosphorylation of the L1ICD enhances binding of the 14-3-3 zeta isoform (14-3-3ζ). Interestingly, in an in vitro phosphorylation assay, 14-3-3ζ promoted CKII-dependent phosphorylation of the L1ICD. Given that L1 phosphorylation by CKII has been implicated in L1-triggered axonal elongation, we investigated the influence of 14-3-3ζ on L1-dependent neurite outgrowth. We found that expression of a mutated form of 14-3-3ζ, which impairs interactions of 14-3-3ζ with its binding partners, stimulated neurite elongation from cultured rat hippocampal neurons, supporting a functional connection between L1 and 14-3-3ζ. CONCLUSIONS/SIGNIFICANCE Our results suggest that 14-3-3ζ, a novel direct binding partner of the L1ICD, promotes L1 phosphorylation by CKII in the central nervous system, and regulates neurite outgrowth, an important biological process triggered by L1.
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Affiliation(s)
- Elisa M. Ramser
- Zentrum für Molekulare Neurobiologie Hamburg, University of Hamburg, Hamburg, Germany
| | - Gerrit Wolters
- Zentrum für Molekulare Neurobiologie Hamburg, University of Hamburg, Hamburg, Germany
| | - Galina Dityateva
- Zentrum für Molekulare Neurobiologie Hamburg, University of Hamburg, Hamburg, Germany
- Department of Neuroscience and Brain Technologies, Italian Institute of Technology, Genova, Italy
| | - Alexander Dityatev
- Zentrum für Molekulare Neurobiologie Hamburg, University of Hamburg, Hamburg, Germany
- Department of Neuroscience and Brain Technologies, Italian Institute of Technology, Genova, Italy
| | - Melitta Schachner
- Zentrum für Molekulare Neurobiologie Hamburg, University of Hamburg, Hamburg, Germany
- Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America
| | - Thomas Tilling
- Zentrum für Molekulare Neurobiologie Hamburg, University of Hamburg, Hamburg, Germany
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19
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Ramser EM, Buck F, Schachner M, Tilling T. Binding of alphaII spectrin to 14-3-3beta is involved in NCAM-dependent neurite outgrowth. Mol Cell Neurosci 2010; 45:66-74. [PMID: 20598904 DOI: 10.1016/j.mcn.2010.05.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Revised: 05/05/2010] [Accepted: 05/18/2010] [Indexed: 11/28/2022] Open
Abstract
Members of the 14-3-3 protein family have been implicated in neuronal migration, synaptic plasticity and learning. Using affinity chromatography followed by mass spectrometry analysis, we show here that the cytoskeletal protein alphaII spectrin is a novel ligand of 14-3-3beta. We found that 14-3-3beta interacts with alphaII spectrin via the mode 2 14-3-3 binding motif RLIQS(1302)HP. Binding required phosphorylation of Ser(1302) by casein kinase II and was enhanced in the presence of calmodulin. Co-immunoprecipitation of alphaII spectrin and 14-3-3beta with the neural cell adhesion molecule NCAM suggested that the 14-3-3-spectrin-interaction affects NCAM function. Indeed, disruption of the 14-3-3beta/alphaII spectrin interaction by mutating Ser(1302) to Ala enhanced NCAM-dependent neurite outgrowth. Our results indicate that the phosphorylation-dependent interaction between 14-3-3beta and alphaII spectrin acts as a switch between positive and negative regulation of neurite outgrowth stimulated by NCAM, representing a novel and acute mechanism preventing uncontrolled elongation of neuronal processes.
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Affiliation(s)
- Elisa M Ramser
- Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany
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20
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Mittelstaedt T, Alvaréz-Baron E, Schoch S. RIM proteins and their role in synapse function. Biol Chem 2010; 391:599-606. [DOI: 10.1515/bc.2010.064] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Abstract
Active zones are specialized areas of the plasma membrane in the presynaptic nerve terminal that mediate neurotransmitter release and synaptic plasticity. The multidomain proteins RIM1 and RIM2 are integral components of the cytomatrix at the active zone, interacting with most other active zone-enriched proteins as well as synaptic vesicle proteins. In the brain, RIMs are present in multiple isoforms (α, β, γ) diverging in their structural composition, which mediate overlapping and distinct functions. Here, we summarize recent findings about the specific roles of the various RIM isoforms in basic synaptic vesicle release as well as long- and short-term presynaptic plasticity.
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21
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Acute in vivo genetic rescue demonstrates that phosphorylation of RIM1alpha serine 413 is not required for mossy fiber long-term potentiation. J Neurosci 2010; 30:2542-6. [PMID: 20164339 DOI: 10.1523/jneurosci.4285-09.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
While presynaptic, protein kinase A (PKA)-dependent, long-term plasticity has been described in numerous brain regions, the target(s) of PKA and the molecular mechanisms leading to sustained changes in neurotransmitter release remain elusive. Here, we acutely reconstitute mossy fiber long-term potentiation (mfLTP) de novo in the mature brains of mutant mice that normally lack this form of plasticity. These results demonstrate that RIM1alpha, a presynaptic scaffold protein and a potential PKA target, can support mfLTP independent of a role in brain development. Using this approach, we study two mutations of RIM1alpha (S413A and V415P) and conclude that PKA-phosphorylation-dependent signaling by RIM1alpha serine 413 is not required for mfLTP, consistent with conclusions reached from the study of RIM1alpha S413A knockin mice. Together, these results provide insights into the mechanism of mossy fiber LTP and demonstrate a useful acute approach to genetically manipulate mossy fiber synapses in the mature brain.
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22
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Grange J, Belly A, Dupas S, Trembleau A, Sadoul R, Goldberg Y. Specific interaction between Sam68 and neuronal mRNAs: implication for the activity-dependent biosynthesis of elongation factor eEF1A. J Neurosci Res 2009; 87:12-25. [PMID: 18711726 DOI: 10.1002/jnr.21824] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In cultured hippocampal neurons and in adult brain, the splicing regulatory protein Sam68 is partially relocated to the somatodendritic domain and associates with dendritic polysomes. Transfer to the dendrites is activity-dependent. We have investigated the repertoire of neuronal mRNAs to which Sam68 binds in vivo. By using coimmunoprecipitation and microarray screening techniques, Sam68 was found to associate with a number of plasticity-related mRNA species, including Eef1a1, an activity-responsive mRNA coding for translation elongation factor eEF1A. In cortical neuronal cultures, translation of the Eef1a1 mRNA was strongly induced by neuronal depolarisation and correlated with enhanced association of Sam68 with polysomal mRNAs. The possible function of Sam68 in Eef1a1 mRNA utilization was studied by expressing a dominant-negative, cytoplasmic Sam68 mutant (GFP-Sam68DeltaC) in cultured hippocampal neurons. The level of eEF1A was lower in neurons expressing GFP-Sam68DeltaC than in control neurons, supporting the proposal that endogenous Sam68 may contribute to the translational efficiency of the Eef1a1 mRNA. These findings are discussed in the light of the complex, potentially crucial regulation of eEF1A biosynthesis during long-term synaptic change.
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Affiliation(s)
- Julien Grange
- Université Joseph Fourier, Grenoble Institute of Neuroscience, Grenoble, France
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23
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RIM1alpha and RIM1beta are synthesized from distinct promoters of the RIM1 gene to mediate differential but overlapping synaptic functions. J Neurosci 2009; 28:13435-47. [PMID: 19074017 DOI: 10.1523/jneurosci.3235-08.2008] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
At a synapse, presynaptic terminals form a specialized area of the plasma membrane called the active zone that mediates neurotransmitter release. RIM1alpha is a multidomain protein that constitutes a central component of the active zone by binding to other active zone proteins such as Munc13 s, alpha-liprins, and ELKS, and to synaptic vesicle proteins such as Rab3 and synaptotagmin-1. In mice, knockout of RIM1alpha significantly impairs synaptic vesicle priming and presynaptic long-term plasticity, but is not lethal. We now find that the RIM1 gene encodes a second, previously unknown RIM1 isoform called RIM1beta that is upregulated in RIM1alpha knock-out mice. RIM1beta is identical to RIM1alpha except for the N terminus where RIM1beta lacks the N-terminal Rab3-binding sequence of RIM1alpha. Using newly generated knock-out mice lacking both RIM1alpha and RIM1beta, we demonstrate that different from the deletion of only RIM1alpha, deletion of both RIM1alpha and RIM1beta severely impairs mouse survival. Electrophysiological analyses show that the RIM1alphabeta deletion abolishes long-term presynaptic plasticity, as does RIM1alpha deletion alone. In contrast, the impairment in synaptic strength and short-term synaptic plasticity that is caused by the RIM1alpha deletion is aggravated by the deletion of both RIM1alpha and RIM1beta. Thus, our data indicate that the RIM1 gene encodes two different isoforms that perform overlapping but distinct functions in neurotransmitter release.
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Umahara T, Uchihara T, Nakamura A, Iwamoto T. Isoform-dependent immunolocalization of 14-3-3 proteins in developing rat cerebellum. Brain Res 2008; 1253:15-26. [PMID: 19070608 DOI: 10.1016/j.brainres.2008.11.065] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Accepted: 11/17/2008] [Indexed: 11/26/2022]
Abstract
We investigated the expression of 14-3-3 protein and its 7 isoforms during postnatal development of rat cerebellum with immunoblot and immunohistochemistry with isoform-specific antibodies. The relative amounts of total 14-3-3 protein, probed by an antibody (14-3-3 COM) recognizing a sequence shared among its isoforms, exhibited no significant changes from postnatal day 2 (P2) to P100. 14-3-3 COM-like immunoreactivity (IR), initially in the apical portion of Purkinje cells at P2, extended to Purkinje cell bodies at P14 and to their dendrites (P100) with increasing intensity. Molecular layer (after P7) and cerebellar nucleus neurons (after P14) were also immunolabeled with this antibody. These chronological changes were shared with those obtained with beta, gamma, and eta isoforms. In contrast, epsilon isoform-like IR was initially identified in processes of radial and Bergmann glia at P2 prior to its appearance in the molecular layer at P7 with subsequent intensification also in Purkinje cells after P14. Zeta and tau isoform-like IR was identified in the white matter and/or in oligodendroglial cells. The sigma isoform was the only isoform exhibiting a significant quantitative change with a peak at P14. Immunolocalization of sigma isoform was initially restricted in several cells in Purkinje cell layer at P2 and shifted to nuclei of external and internal granule cells and Purkinje cells after P14, whereas its immunolabeling was markedly weaker at P100. Different immunolocalizations of the 7 isoforms suggest that 14-3-3 protein isoforms individually associate with the neuronal and glial proliferation, differentiation, migration and development during postnatal formation of rat cerebellum.
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Affiliation(s)
- Takahiko Umahara
- Department of Geriatric Medicine, Tokyo Medical University, Tokyo, Japan.
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25
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RIM1alpha phosphorylation at serine-413 by protein kinase A is not required for presynaptic long-term plasticity or learning. Proc Natl Acad Sci U S A 2008; 105:14680-5. [PMID: 18799741 DOI: 10.1073/pnas.0806679105] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Activation of presynaptic cAMP-dependent protein kinase A (PKA) triggers presynaptic long-term plasticity in synapses such as cerebellar parallel fiber and hippocampal mossy fiber synapses. RIM1alpha, a large multidomain protein that forms a scaffold at the presynaptic active zone, is essential for presynaptic long-term plasticity in these synapses and is phosphorylated by PKA at serine-413. Previous studies suggested that phosphorylation of RIM1alpha at serine-413 is required for presynaptic long-term potentiation in parallel fiber synapses formed in vitro by cultured cerebellar neurons and that this type of presynaptic long-term potentiation is mediated by binding of 14-3-3 proteins to phosphorylated serine-413. To test the role of serine-413 phosphorylation in vivo, we have now produced knockin mice in which serine-413 is mutated to alanine. Surprisingly, we find that in these mutant mice, three different forms of presynaptic PKA-dependent long-term plasticity are normal. Furthermore, we observed that in contrast to RIM1alpha KO mice, RIM1 knockin mice containing the serine-413 substitution exhibit normal learning capabilities. The lack of an effect of the serine-413 mutation of RIM1alpha is not due to compensation by RIM2alpha because mice carrying both the serine-413 substitution and a RIM2alpha deletion still exhibited normal long-term presynaptic plasticity. Thus, phosphorylation of serine-413 of RIM1alpha is not essential for PKA-dependent long-term presynaptic plasticity in vivo, suggesting that PKA operates by a different mechanism despite the dependence of long-term presynaptic plasticity on RIM1alpha.
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Simsek-Duran F, Lonart G. The role of RIM1alpha in BDNF-enhanced glutamate release. Neuropharmacology 2008; 55:27-34. [PMID: 18499195 DOI: 10.1016/j.neuropharm.2008.04.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2007] [Revised: 03/14/2008] [Accepted: 04/11/2008] [Indexed: 11/30/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is known to activate proline-directed Ser/Thr protein kinases and to enhance glutamatergic transmission via a Rab3a-dependent molecular pathway. The identity of molecular targets in BDNF's action on Rab3a pathway, a synaptic vesicle protein involved in vesicle trafficking and synaptic plasticity, is not fully known. Here we demonstrate that BDNF enhances depolarization-evoked efflux of [(3)H]-glutamate from nerve terminals isolated from the CA1 region of the hippocampus. BDNF also potentiated hyperosmotic shock-evoked [(3)H]-glutamate efflux, indicating an effect on the size of the readily releasable pool. This effect of BDNF was completely abolished in nerve terminals derived from Rim1alphaKO (Rab3 interacting molecule 1alpha null mutant) mice. Using in vitro phosphorylation assays we identified two novel phosphorylation sites, Ser447 and Ser745 that were substrates for ERK2, a proline-directed kinase known to be activated by BDNF. The pSer447 site was phosphorylated under resting conditions in hippocampal CA1 nerve terminals and its phosphorylation was enhanced by BDNF treatment, as indicated by the use of a pSer447-RIM1alpha antibody we have developed. Together these findings identify RIM1alpha, a component of the Rab3a molecular pathway in mediating presynaptic plasticity, as a necessary factor in BDNF's enhancement of [(3)H]-glutamate efflux from hippocampal CA1 nerve terminals and indicate a possible role for RIM1alpha phosphorylation in BDNF-dependent presynaptic plasticity.
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Affiliation(s)
- Fatma Simsek-Duran
- Department of Pathology and Anatomy, Eastern Virginia Medical School, 700 W. Olney Road Norfolk, VA 23507, USA
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Lonart G, Tang X, Simsek-Duran F, Machida M, Sanford LD. The role of active zone protein Rab3 interacting molecule 1 alpha in the regulation of norepinephrine release, response to novelty, and sleep. Neuroscience 2008; 154:821-31. [PMID: 18495360 DOI: 10.1016/j.neuroscience.2008.03.047] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 03/15/2008] [Accepted: 03/18/2008] [Indexed: 11/15/2022]
Abstract
Sleep mechanisms and synaptic plasticity are thought to interact to regulate homeostasis and memory formation. However, the influences of molecules that mediate synaptic plasticity on sleep are not well understood. In this study we demonstrate that mice lacking Rab3 interacting molecule 1 alpha (RIM1 alpha) (Rim1 alpha KO), a protein of the synaptic active zone required for certain types of synaptic plasticity and learning, had 53+/-5% less baseline rapid eye movement (REM) sleep compared with their wild type littermates. Also, compared with wild type littermates, exposure of the mice to an open field or to a novel object induced more robust and longer lasting locomotion suggesting altered habituation. This difference in exploratory behavior correlated with genotype specific changes in REM and deregulated release of norepinephrine in the cortex and basal amygdala of the Rim1 alpha KO mice. Also, moderate sleep deprivation (4 h), a test of the homeostatic sleep response, induced REM sleep rebound with different time course in Rim1 alpha KO and their wild type littermates. As norepinephrine plays an important role in regulating arousal and REM sleep, our data suggest that noradrenergic deficiency in Rim1 alpha KO animals impacts exploratory behavior and sleep regulation and contributes to impairments in learning.
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Affiliation(s)
- G Lonart
- Department of Pathology and Anatomy, Eastern Virginia Medical School, Norfolk, VA 23507, USA.
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Crow T, Xue-Bian JJ, Neary JT. 14-3-3 proteins interact with the beta-thymosin repeat protein Csp24. Neurosci Lett 2007; 424:6-9. [PMID: 17709188 PMCID: PMC2695760 DOI: 10.1016/j.neulet.2007.07.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Accepted: 07/07/2007] [Indexed: 12/29/2022]
Abstract
Conditioned stimulus pathway protein 24 (Csp24) is a beta-thymosin-like protein that is homologous to other members of the family of beta-thymosin repeat proteins that contain multiple actin binding domains. Actin co-precipitates with Csp24 and co-localizes with it in the cytosol of type-B photoreceptor cell bodies. Several signal transduction pathways have been shown to regulate the phosphorylation of Csp24 and contribute to cellular plasticity. Here, we report the identification of the adapter protein 14-3-3 in lysates of the Hermissenda circumesophageal nervous system and its interaction with Csp24. Immunoprecipitation experiments using an antibody that is broadly reactive with several isoforms of the 14-3-3 family of proteins showed that Csp24 co-precipitates with 14-3-3 protein, and nervous systems stimulated with 5-HT exhibited a significant increase in co-precipitated Csp24 probed with a phosphospecific antibody as compared with controls. These results indicate that post-translational modifications of Csp24 regulate its interaction with 14-3-3 protein, and suggest that this mechanism may contribute to the control of intrinsic enhanced excitability.
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Affiliation(s)
- Terry Crow
- Department of Neurobiology and Anatomy, University of Texas Medical School, 6431 Fannin Street, Houston, TX 77030, USA.
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29
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Abstract
A major goal of learning and memory research is to correlate the function of molecules with the behaviour of organisms. The beautiful laminar structure of the cerebellar cortex lends itself to the study of synaptic plasticity, because its clearly defined patterns of neurons and their synapses form circuits that have been implicated in simple motor behaviour paradigms. The best understood in terms of molecular mechanism is the parallel fibre-Purkinje cell synapse, where presynaptic long-term potentiation and postsynaptic long-term depression and potentiation finely tune cerebellar output. Our understanding of these forms of plasticity has mostly come from the electrophysiological and behavioural analysis of knockout mutant mice, but more recently the knock-in of synaptic molecules with mutated phosphorylation sites and binding domains has provided more detailed insights into the signalling events. The present review details the major forms of plasticity in the cerebellar cortex, with particular attention to the membrane trafficking and intracellular signalling responsible. This overview of the current literature suggests it will not be long before the involvement of the cerebellum in certain motor behaviours is fully explained in molecular terms.
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Affiliation(s)
- Gareth J O Evans
- Department of Biology (Area 3), University of York, Heslington, York, UK.
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30
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Chang CC, Eggers SD, Johnson JK, Haman A, Miller BL, Geschwind MD. Anti-GAD antibody cerebellar ataxia mimicking Creutzfeldt–Jakob disease. Clin Neurol Neurosurg 2007; 109:54-7. [PMID: 16621241 DOI: 10.1016/j.clineuro.2006.01.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Revised: 12/24/2005] [Accepted: 01/11/2006] [Indexed: 11/24/2022]
Abstract
In a patient with a rapidly progressive neurological condition with ataxia and cognitive complaints, Creutzfeldt-Jakob disease (CJD) is often high in the differential, particularly when there is an elevated CSF 14-3-3 protein level. We present a case of anti-glutamic acid decarboxylase antibody (anti-GAD65) positive cerebellar ataxia associated with cognitive complaints and elevated CSF 14-3-3 protein.
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Affiliation(s)
- Chiung-Chih Chang
- University of California San Francisco, Department of Neurology, Memory & Aging Center, Box 1207, San Francisco, CA 94143-1207, USA
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31
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Meiri N. 14-3-3ε Expression is induced during the critical period of thermal control establishment. Dev Neurobiol 2007; 68:62-72. [DOI: 10.1002/dneu.20571] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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32
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Schoch S, Mittelstaedt T, Kaeser PS, Padgett D, Feldmann N, Chevaleyre V, Castillo PE, Hammer RE, Han W, Schmitz F, Lin W, Südhof TC. Redundant functions of RIM1alpha and RIM2alpha in Ca(2+)-triggered neurotransmitter release. EMBO J 2006; 25:5852-63. [PMID: 17124501 PMCID: PMC1698877 DOI: 10.1038/sj.emboj.7601425] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Accepted: 10/13/2006] [Indexed: 11/08/2022] Open
Abstract
Alpha-RIMs (RIM1alpha and RIM2alpha) are multidomain active zone proteins of presynaptic terminals. Alpha-RIMs bind to Rab3 on synaptic vesicles and to Munc13 on the active zone via their N-terminal region, and interact with other synaptic proteins via their central and C-terminal regions. Although RIM1alpha has been well characterized, nothing is known about the function of RIM2alpha. We now show that RIM1alpha and RIM2alpha are expressed in overlapping but distinct patterns throughout the brain. To examine and compare their functions, we generated knockout mice lacking RIM2alpha, and crossed them with previously produced RIM1alpha knockout mice. We found that deletion of either RIM1alpha or RIM2alpha is not lethal, but ablation of both alpha-RIMs causes postnatal death. This lethality is not due to a loss of synapse structure or a developmental change, but to a defect in neurotransmitter release. Synapses without alpha-RIMs still contain active zones and release neurotransmitters, but are unable to mediate normal Ca(2+)-triggered release. Our data thus demonstrate that alpha-RIMs are not essential for synapse formation or synaptic exocytosis, but are required for normal Ca(2+)-triggering of exocytosis.
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Affiliation(s)
- Susanne Schoch
- Emmy Noether Research Group, Institute of Neuropathology, Department of Epileptology, University Bonn, Sigmund Freud Strasse 25, 53105 Bonn, Germany.
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33
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Li Y, Wu Y, Zhou Y. Modulation of inactivation properties of CaV2.2 channels by 14-3-3 proteins. Neuron 2006; 51:755-71. [PMID: 16982421 DOI: 10.1016/j.neuron.2006.08.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Revised: 05/08/2006] [Accepted: 08/08/2006] [Indexed: 11/28/2022]
Abstract
Inactivation of presynaptic Ca(V)2.2 channels may play a role in regulating short-term synaptic plasticity. Here, we report a direct modulation of Ca(V)2.2 channel inactivation properties by 14-3-3, a family of signaling proteins involved in a wide range of biological processes. The structural elements critical for 14-3-3 binding and channel modulation lie in the carboxyl tail of the pore-forming alpha(1B) subunit, where we have identified two putative 14-3-3 interaction sites, including a phosphoserine-containing motif that directly binds to 14-3-3 and a second region near the EF hand and IQ domain. In transfected tsA 201 cells, 14-3-3 coexpression dramatically slows open-state inactivation and reduces cumulative inactivation of Ca(V)2.2 channels. In hippocampal neurons, interference with 14-3-3 binding accelerates Ca(V)2.2 channel inactivation and enhances short-term synaptic depression. These results demonstrate that 14-3-3 proteins are important regulators of Ca(V)2.2 channel activities and through this mechanism may contribute to their regulation of synaptic transmission and plasticity.
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MESH Headings
- 14-3-3 Proteins/genetics
- 14-3-3 Proteins/metabolism
- 14-3-3 Proteins/physiology
- Amino Acid Sequence
- Animals
- Binding Sites/genetics
- Binding, Competitive
- Blotting, Western
- Brain/cytology
- Brain/metabolism
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Channels, N-Type/genetics
- Calcium Channels, N-Type/metabolism
- Calcium Channels, T-Type/genetics
- Calcium Channels, T-Type/metabolism
- Cell Line
- Cells, Cultured
- Glutathione Transferase/genetics
- Glutathione Transferase/metabolism
- Humans
- Neurons/cytology
- Neurons/metabolism
- Phosphorylation
- Protein Binding
- Protein Subunits/genetics
- Protein Subunits/metabolism
- Rats
- Rats, Sprague-Dawley
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Synaptic Transmission/physiology
- Time Factors
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Affiliation(s)
- Yong Li
- Department of Neurobiology, Evelyn F. McKnight Brain Institute and Civitan International Research Center, School of Medicine, University of Alabama at Birmingham, 35294, USA
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34
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Schoch S, Gundelfinger ED. Molecular organization of the presynaptic active zone. Cell Tissue Res 2006; 326:379-91. [PMID: 16865347 DOI: 10.1007/s00441-006-0244-y] [Citation(s) in RCA: 223] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Accepted: 05/10/2006] [Indexed: 11/26/2022]
Abstract
The exocytosis of neurotransmitter-filled synaptic vesicles is under tight temporal and spatial control in presynaptic nerve terminals. The fusion of synaptic vesicles is restricted to a specialized area of the presynaptic plasma membrane: the active zone. The protein network that constitutes the cytomatrix at the active zone (CAZ) is involved in the organization of docking and priming of synaptic vesicles and in mediating use-dependent changes in release during short-term and long-term synaptic plasticity. To date, five protein families whose members are highly enriched at active zones (Munc13s, RIMs, ELKS proteins, Piccolo and Bassoon, and the liprins-alpha), have been characterized. These multidomain proteins are instrumental for the diverse functions performed by the presynaptic active zone.
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Affiliation(s)
- Susanne Schoch
- Emmy Noether Research Group, Institute of Neuropathology and Department of Epileptology, University of Bonn Medical Center, Sigmund Freud Strasse 25, 53105 Bonn, Germany.
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35
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Leng Y, Chuang DM. Endogenous alpha-synuclein is induced by valproic acid through histone deacetylase inhibition and participates in neuroprotection against glutamate-induced excitotoxicity. J Neurosci 2006; 26:7502-12. [PMID: 16837598 PMCID: PMC6674182 DOI: 10.1523/jneurosci.0096-06.2006] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Emerging evidence suggests that alpha-synuclein (alpha-syn), which is traditionally thought to have a pathophysiological role in neurodegenerative diseases, can have neuroprotective effects. This study aimed to investigate whether endogenous alpha-syn in neurons can be induced by valproic acid (VPA), a mood-stabilizer, anticonvulsant and histone deacetylase (HDAC) inhibitor, and if so, whether the alpha-syn induction is neuroprotective. VPA treatment of rat cerebellar granule cells caused a robust dose- and time-dependent increase in levels of alpha-syn protein and mRNA and in the intensity of alpha-syn immunostaining. Knockdown of VPA-induced alpha-syn overexpression with alpha-syn antisense oligonucleotides or siRNA completely blocked VPA-induced neuroprotection. alpha-Syn knockdown also exacerbated glutamate neurotoxicity, stimulated the expression of the proapoptotic gene ubiquitin-conjugating enzyme E2N, and downregulated the expression of the anti-apoptotic gene Bcl-2. Induction of alpha-syn by VPA was associated with inhibition of HDAC activity, resulting in hyperacetylation of histone H3 in the alpha-syn promoter and a marked increase in alpha-syn promoter activity. Moreover, VPA-induced alpha-syn induction and neuroprotection were mimicked by HDAC inhibitors sodium 4-phenylbutyrate and trichostatin A (TSA). alpha-syn was also induced by VPA in rat cerebral cortical neurons. Additionally, treatment of rats with VPA, sodium butyrate, or TSA markedly increased alpha-syn protein levels in the cortex and cerebellum. Together, our results demonstrate for the first time that VPA induces alpha-syn in neurons through inhibition of HDAC and that this alpha-syn induction is critically involved in neuroprotection against glutamate excitotoxicity. Clinically, VPA may represent a suitable treatment for excitotoxicity-related neurodegenerative diseases.
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36
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Lonart G, Simsek-Duran F. Deletion of synapsins I and II genes alters the size of vesicular pools and rabphilin phosphorylation. Brain Res 2006; 1107:42-51. [PMID: 16844103 DOI: 10.1016/j.brainres.2006.05.092] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Revised: 05/04/2006] [Accepted: 05/28/2006] [Indexed: 01/21/2023]
Abstract
Previous studies established that genetic deletion of synapsins, synaptic vesicle-associated phosphoproteins that regulate neurotransmitter release, decreases the number of synaptic vesicles in nerve terminals. To investigate whether these changes affect the release properties of the remaining synaptic vesicles, we used a radioactive labeling technique to measure release independently of the total number of synaptic vesicles. 3H-glutamate and 14C-gamma-amino-butyric-acid (GABA) release from isolated nerve terminals prepared from the neocortex of synapsins I and II double knock-out mice (DKO) was assayed and compared to wild-type preparations. Hyperosmotic shock-evoked 3H-glutamate was reduced by 20+/-3% from DKO nerve terminals and potassium depolarization-evoked glutamate release was also decreased by 28+/-2%. Surprisingly, sucrose or potassium depolarization-evoked release of 14C-GABA was increased by 32+/-4% and 29+/-5%, respectively. The basal efflux of both 3H-glutamate and 14C-GABA increased by 17+/-2% and 12+/-2% from DKO nerve terminals. As lack of synapsins I and II, major phosphoproteins of synaptic vesicles, may lead to deregulation of phosphorylation events, we compared phosphorylation state of another synaptic vesicle protein, rabphilin. In DKO nerve terminals, membrane-associated rabphilin level was reduced by approximately 0.28-fold, its phosphorylation at 234serine was increased by approximately 1.61-fold whereas cytosolic rabphilin levels showed both more dramatic reduction in abundance, approximately 16.5-fold, and increase in phosphorylation, approximately 4.8-fold. Collectively, these data suggest that deletion of major synapsin isoforms leads to (1) deregulation of basal neurotransmission causing "leaky" basal release, (2) changes in either the size or mobilization of releasable or reserve pools, and (3) a decrease in rabphilin abundance accompanied by an increase in basal phosphorylation of the remaining rabphilin.
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Affiliation(s)
- György Lonart
- Department of Pathology and Anatomy, Eastern Virginia Medical School, 700 W. Olney Rd. Norfolk, VA 23507, USA.
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Fejtova A, Gundelfinger ED. Molecular organization and assembly of the presynaptic active zone of neurotransmitter release. Results Probl Cell Differ 2006; 43:49-68. [PMID: 17068967 DOI: 10.1007/400_012] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
At chemical synapses, neurotransmitter is released at a restricted region of the presynaptic plasma membrane, called the active zone. At the active zone, a matrix of proteins is assembled, which is termed the presynaptic grid or cytomatrix at the active zone (CAZ). Components of the CAZ are thought to localize and organize the synaptic vesicle cycle, a series of membrane trafficking events underlying regulated neurotransmitter exocytosis. This review is focused on a set of specific proteins involved in the structural and functional organization of the CAZ. These include the multi-domain Rab3-effector proteins RIM1alpha and RIM2alpha; Bassoon and Piccolo, two multi-domain CAZ scaffolding proteins of enormous size; as well as members of the CAST/ERC family of CAZ-specific structural proteins. Studies on ribbon synapses of retinal photoreceptor cells have fostered understanding the molecular design of the CAZ. In addition, the analysis of the delivery pathways for Bassoon and Piccolo to presynaptic sites during development has produced new insights into assembly mechanisms of brain synapses during development. Based on these studies, the active zone transport vesicle hypothesis was formulated, which postulates that active zones, at least in part, are pre-assembled in neuronal cell bodies and transported as so-called Piccolo-Bassoon transport vesicles (PTVs) to sites of synaptogenesis. Several PTVs can fuse on demand with the presynaptic membrane to rapidly form an active zone.
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Affiliation(s)
- Anna Fejtova
- Leibniz Institute for Neurobiology, Department of Neurochemistry and Molecular Biology, Magdeburg, Germany.
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38
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Abstract
RIM1alpha (Rab3-interacting molecule 1alpha) is a large multidomain protein that is localized to presynaptic active zones [Wang, Okamoto, Schmitz, Hofmann and Südhof (1997) Nature (London) 388, 593-598] and is the founding member of the RIM protein family that also includes RIM2alpha, 2beta, 2gamma, 3gamma and 4gamma [Wang and Südhof (2003) Genomics 81, 126-137]. In presynaptic nerve termini, RIM1alpha interacts with a series of presynaptic proteins, including the synaptic vesicle GTPase Rab3 and the active zone proteins Munc13, liprins and ELKS (a protein rich in glutamate, leucine, lysine and serine). Mouse KOs (knockouts) revealed that, in different types of synapses, RIM1alpha is essential for different forms of synaptic plasticity. In CA1-region Schaffer-collateral excitatory synapses and in GABAergic synapses (where GABA is gamma-aminobutyric acid), RIM1alpha is required for maintaining normal neurotransmitter release and short-term synaptic plasticity. In contrast, in excitatory CA3-region mossy fibre synapses and cerebellar parallel fibre synapses, RIM1alpha is necessary for presynaptic long-term, but not short-term, synaptic plasticity. In these synapses, the function of RIM1alpha in presynaptic long-term plasticity depends, at least in part, on phosphorylation of RIM1alpha at a single site, suggesting that RIM1alpha constitutes a 'phosphoswitch' that determines synaptic strength. However, in spite of the progress in understanding RIM1alpha function, the mechanisms by which RIM1alpha acts remain unknown. For example, how does phosphorylation regulate RIM1alpha, what is the relationship of the function of RIM1alpha in basic release to synaptic plasticity and what is the physiological significance of different forms of RIM-dependent plasticity? Moreover, the roles of other RIM isoforms are unclear. Addressing these important questions will contribute to our view of how neurotransmitter release is regulated at the presynaptic active zone.
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39
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Sung U, Jennings JL, Link AJ, Blakely RD. Proteomic analysis of human norepinephrine transporter complexes reveals associations with protein phosphatase 2A anchoring subunit and 14-3-3 proteins. Biochem Biophys Res Commun 2005; 333:671-8. [PMID: 15963952 DOI: 10.1016/j.bbrc.2005.05.165] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Accepted: 05/25/2005] [Indexed: 11/29/2022]
Abstract
The norepinephrine transporter (NET) terminates noradrenergic signals by clearing released NE at synapses. NET regulation by receptors and intracellular signaling pathways is supported by a growing list of associated proteins including syntaxin1A, protein phosphatase 2A (PP2A) catalytic subunit (PP2A-C), PICK1, and Hic-5. In the present study, we sought evidence for additional partnerships by mass spectrometry-based analysis of proteins co-immunoprecipitated with human NET (hNET) stably expressed in a mouse noradrenergic neuroblastoma cell line. Our initial proteomic analyses reveal multiple peptides derived from hNET, peptides arising from the mouse PP2A anchoring subunit (PP2A-Ar) and peptides derived from 14-3-3 proteins. We verified physical association of NET with PP2A-Ar via co-immunoprecipitation studies using mouse vas deferens extracts and with 14-3-3 via a fusion pull-down approach, implicating specifically the hNET NH2-terminus for interactions. The transporter complexes described likely support mechanisms regulating transporter activity, localization, and trafficking.
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Affiliation(s)
- Uhna Sung
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, USA
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