1
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Zhang H, Lei M, Zhang Y, Li H, He Z, Xie S, Zhu L, Wang S, Liu J, Li Y, Lu Y, Ma C. Phosphorylation of Doc2 by EphB2 modulates Munc13-mediated SNARE complex assembly and neurotransmitter release. SCIENCE ADVANCES 2024; 10:eadi7024. [PMID: 38758791 PMCID: PMC11100570 DOI: 10.1126/sciadv.adi7024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 04/12/2024] [Indexed: 05/19/2024]
Abstract
At the synapse, presynaptic neurotransmitter release is tightly controlled by release machinery, involving the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins and Munc13. The Ca2+ sensor Doc2 cooperates with Munc13 to regulate neurotransmitter release, but the underlying mechanisms remain unclear. In our study, we have characterized the binding mode between Doc2 and Munc13 and found that Doc2 originally occludes Munc13 to inhibit SNARE complex assembly. Moreover, our investigation unveiled that EphB2, a presynaptic adhesion molecule (SAM) with inherent tyrosine kinase functionality, exhibits the capacity to phosphorylate Doc2. This phosphorylation attenuates Doc2 block on Munc13 to promote SNARE complex assembly, which functionally induces spontaneous release and synaptic augmentation. Consistently, application of a Doc2 peptide that interrupts Doc2-Munc13 interplay impairs excitatory synaptic transmission and leads to dysfunction in spatial learning and memory. These data provide evidence that SAMs modulate neurotransmitter release by controlling SNARE complex assembly.
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Affiliation(s)
- Hong Zhang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Mengshi Lei
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Yu Zhang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Hao Li
- Institute for Brain Research, Wuhan Center of Brain Science, Huazhong University of Science and Technology, Wuhan 430030, China
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Zhen He
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Sheng Xie
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Le Zhu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Shen Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Jianfeng Liu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Yan Li
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Youming Lu
- Institute for Brain Research, Wuhan Center of Brain Science, Huazhong University of Science and Technology, Wuhan 430030, China
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Cong Ma
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
- Institute for Brain Research, Wuhan Center of Brain Science, Huazhong University of Science and Technology, Wuhan 430030, China
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2
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Mao LM, Thallapureddy K, Wang JQ. Effects of propofol on presynaptic synapsin phosphorylation in the mouse brain in vivo. Brain Res 2024; 1823:148671. [PMID: 37952872 PMCID: PMC10806815 DOI: 10.1016/j.brainres.2023.148671] [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: 08/10/2023] [Revised: 10/24/2023] [Accepted: 11/07/2023] [Indexed: 11/14/2023]
Abstract
The commonly used general anesthetic propofol can enhance the γ-aminobutyric acid-mediated inhibitory synaptic transmission and depress the glutamatergic excitatory synaptic transmission to achieve general anesthesia and other outcomes. In addition to the actions at postsynaptic sites, the modulation of presynaptic activity by propofol is thought to contribute to neurophysiological effects of the anesthetic, although potential targets of propofol within presynaptic nerve terminals are incompletely studied at present. In this study, we explored the possible linkage of propofol to synapsins, a family of neuron-specific phosphoproteins which are the most abundant proteins on presynaptic vesicles, in the adult mouse brain in vivo. We found that an intraperitoneal injection of propofol at a dose that caused loss of righting reflex increased basal levels of synapsin phosphorylation at the major representative phosphorylation sites (serine 9, serine 62/67, and serine 603) in the prefrontal cortex (PFC) of male and female mice. Propofol also elevated synapsin phosphorylation at these sites in the striatum and S9 and S62/67 phosphorylation in the hippocampus, while propofol had no effect on tyrosine hydroxylase phosphorylation in striatal nerve terminals. Total synapsin protein expression in the PFC, hippocampus, and striatum was not altered by propofol. These results reveal that synapsin could be a novel substrate of propofol in the presynaptic neurotransmitter release machinery. Propofol possesses the ability to upregulate synapsin phosphorylation in broad mouse brain regions.
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Affiliation(s)
- Li-Min Mao
- Department of Biomedical Sciences, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Khyathi Thallapureddy
- Department of Biomedical Sciences, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - John Q Wang
- Department of Biomedical Sciences, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA; Department of Anesthesiology, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA.
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3
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Longhena F, Faustini G, Brembati V, Pizzi M, Benfenati F, Bellucci A. An updated reappraisal of synapsins: structure, function and role in neurological and psychiatric disorders. Neurosci Biobehav Rev 2021; 130:33-60. [PMID: 34407457 DOI: 10.1016/j.neubiorev.2021.08.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 07/29/2021] [Accepted: 08/09/2021] [Indexed: 01/02/2023]
Abstract
Synapsins (Syns) are phosphoproteins strongly involved in neuronal development and neurotransmitter release. Three distinct genes SYN1, SYN2 and SYN3, with elevated evolutionary conservation, have been described to encode for Synapsin I, Synapsin II and Synapsin III, respectively. Syns display a series of common features, but also exhibit distinctive localization, expression pattern, post-translational modifications (PTM). These characteristics enable their interaction with other synaptic proteins, membranes and cytoskeletal components, which is essential for the proper execution of their multiple functions in neuronal cells. These include the control of synapse formation and growth, neuron maturation and renewal, as well as synaptic vesicle mobilization, docking, fusion, recycling. Perturbations in the balanced expression of Syns, alterations of their PTM, mutations and polymorphisms of their encoding genes induce severe dysregulations in brain networks functions leading to the onset of psychiatric or neurological disorders. This review presents what we have learned since the discovery of Syn I in 1977, providing the state of the art on Syns structure, function, physiology and involvement in central nervous system disorders.
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Affiliation(s)
- Francesca Longhena
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
| | - Gaia Faustini
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
| | - Viviana Brembati
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
| | - Marina Pizzi
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
| | - Fabio Benfenati
- Italian Institute of Technology, Via Morego 30, Genova, Italy; IRCSS Policlinico San Martino Hospital, Largo Rosanna Benzi 10, 16132, Genova, Italy.
| | - Arianna Bellucci
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy; Laboratory for Preventive and Personalized Medicine, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
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4
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Maiole F, Tedeschi G, Candiani S, Maragliano L, Benfenati F, Zullo L. Synapsins are expressed at neuronal and non-neuronal locations in Octopus vulgaris. Sci Rep 2019; 9:15430. [PMID: 31659209 PMCID: PMC6817820 DOI: 10.1038/s41598-019-51899-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Accepted: 10/10/2019] [Indexed: 12/19/2022] Open
Abstract
Synapsins are a family of phosphoproteins fundamental to the regulation of neurotransmitter release. They are typically neuron-specific, although recent evidence pointed to their expression in non-neuronal cells where they play a role in exocytosis and vesicle trafficking. In this work, we characterized synapsin transcripts in the invertebrate mollusk Octopus vulgaris and present evidence of their expression not only in the brain but also in male and female reproductive organs. We identified three synapsin isoforms phylogenetically correlated to that of other invertebrates and with a modular structure characteristic of mammalian synapsins with a central, highly conserved C domain, important for the protein functions, and less conserved A, B and E domains. Our molecular modeling analysis further provided a solid background for predicting synapsin functional binding to ATP, actin filaments and secretory vesicles. Interestingly, we found that synapsin expression in ovary and testis increased during sexual maturation in cells with a known secretory role, potentially matching the occurrence of a secretion process. This might indicate that its secretory role has evolved across animals according to cell activity in spite of cell identity. We believe that this study may yield insights into the convergent evolution of ubiquitously expressed proteins between vertebrates and invertebrates.
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Affiliation(s)
- Federica Maiole
- Center for Micro-BioRobotics & Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132, Genova, Italy.,Department of Experimental Medicine, University of Genova, viale Benedetto XV, 3, 16132, Genova, Italy
| | - Giulia Tedeschi
- Department of Experimental Medicine, University of Genova, viale Benedetto XV, 3, 16132, Genova, Italy.,Department of Biomedical Engineering, Laboratory for Fluorescence Dynamics, University of California, Irvine, 92697, CA, USA
| | - Simona Candiani
- Laboratory of Developmental Neurobiology, Department of Earth, Environment and Life Sciences, University of Genoa, Viale Benedetto XV 5, 16132, Genoa, Italy.
| | - Luca Maragliano
- Center for Micro-BioRobotics & Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132, Genova, Italy.,IRCSS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132, Genova, Italy
| | - Fabio Benfenati
- Center for Micro-BioRobotics & Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132, Genova, Italy.,IRCSS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132, Genova, Italy
| | - Letizia Zullo
- Center for Micro-BioRobotics & Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132, Genova, Italy. .,IRCSS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132, Genova, Italy.
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5
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Marte A, Russo I, Rebosio C, Valente P, Belluzzi E, Pischedda F, Montani C, Lavarello C, Petretto A, Fedele E, Baldelli P, Benfenati F, Piccoli G, Greggio E, Onofri F. Leucine‐rich repeat kinase 2 phosphorylation on synapsin I regulates glutamate release at pre‐synaptic sites. J Neurochem 2019; 150:264-281. [PMID: 31148170 DOI: 10.1111/jnc.14778] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 05/20/2019] [Accepted: 05/28/2019] [Indexed: 12/25/2022]
Abstract
Leucine-rich repeat kinase 2 (LRRK2) is a large multidomain scaffolding protein with kinase and GTPase activities involved in synaptic vesicle (SV) dynamics. While its role in Parkinson's disease has been largely investigated, little is known about LRRK2 physiological role and until now few proteins have been described as substrates. We have previously demonstrated that LRRK2 through its WD40 domain interacts with synapsin I, an important SV-associated phosphoprotein involved in neuronal development and in the regulation of neurotransmitter release. To test whether synapsin I is substrate for LRRK2 and characterize the properties of its phosphorylation, we used in vitro kinase and binding assays as well as cellular model and site-direct mutagenesis. Using synaptosomes in superfusion, patch-clamp recordings in autaptic WT and synapsin I KO cortical neurons and SypHy assay on primary cortical culture from wild-type and BAC human LRRK2 G2019S mice we characterized the role of LRRK2 kinase activity on glutamate release and SV trafficking. Here we reported that synapsin I is phosphorylated by LRRK2 and demonstrated that the interaction between LRRK2 WD40 domain and synapsin I is crucial for this phosphorylation. Moreover, we showed that LRRK2 phosphorylation of synapsin I at threonine 337 and 339 significantly reduces synapsin I-SV/actin interactions. Using complementary experimental approaches, we demonstrated that LRRK2 controls glutamate release and SV dynamics in a kinase activity and synapsin I-dependent manner. Our findings show that synapsin I is a LRRK2 substrate and describe a novel mechanisms of regulation of glutamate release by LRRK2 kinase activity.
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Affiliation(s)
- Antonella Marte
- Department of Experimental Medicine University of Genova Genova Italy
| | | | | | - Pierluigi Valente
- Department of Experimental Medicine University of Genova Genova Italy
- IRCCS Ospedale Policlinico San Martino Genova Italy
| | - Elisa Belluzzi
- Rheumatology Unit, Department of Medicine‐DIMED University Hospital of Padova Padova Italy
| | - Francesca Pischedda
- Center for Integrative Biology (CIBIO) University of Trento Trento Italy
- Dulbecco Telethon Institute Trento Italy
| | - Caterina Montani
- Center for Integrative Biology (CIBIO) University of Trento Trento Italy
- Dulbecco Telethon Institute Trento Italy
| | - Chiara Lavarello
- Laboratory of Mass Spectrometry ‐ Core Facilities Istituto Giannina Gaslini Genova Italy
| | - Andrea Petretto
- Laboratory of Mass Spectrometry ‐ Core Facilities Istituto Giannina Gaslini Genova Italy
| | - Ernesto Fedele
- Department of Pharmacy University of Genova Genova Italy
- IRCCS Ospedale Policlinico San Martino Genova Italy
| | - Pietro Baldelli
- Department of Experimental Medicine University of Genova Genova Italy
- IRCCS Ospedale Policlinico San Martino Genova Italy
| | - Fabio Benfenati
- IRCCS Ospedale Policlinico San Martino Genova Italy
- Center for Synaptic Neuroscience and Technology Istituto Italiano di Tecnologia Genova Italy
| | - Giovanni Piccoli
- Center for Integrative Biology (CIBIO) University of Trento Trento Italy
- Dulbecco Telethon Institute Trento Italy
| | - Elisa Greggio
- Department of Biology University of Padova Padova Italy
| | - Franco Onofri
- Department of Experimental Medicine University of Genova Genova Italy
- IRCCS Ospedale Policlinico San Martino Genova Italy
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6
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Dalgarno R, Leduc-Pessah H, Pilapil A, Kwok CH, Trang T. Intrathecal delivery of a palmitoylated peptide targeting Y382-384 within the P2X7 receptor alleviates neuropathic pain. Mol Pain 2018; 14:1744806918795793. [PMID: 30146934 PMCID: PMC6111392 DOI: 10.1177/1744806918795793] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Pain hypersensitivity resulting from peripheral nerve injury depends on
pathological microglial activation in the dorsal horn of the spinal cord. This
microglial activity is critically modulated by P2X7 receptors (P2X7R) and ATP
stimulation of these receptors produces mechanical allodynia, a defining feature
of neuropathic pain. Peripheral nerve injury increases P2X7R expression and
potentiates its cation channel function in spinal microglia. Here, we report a
means to preferentially block the potentiation of P2X7R function by delivering a
membrane permeant small interfering peptide that targets Y382-384, a
putative tyrosine phosphorylation site within the P2X7R intracellular C-terminal
domain. Intrathecal administration of this palmitoylated peptide
(P2X7R379-389) transiently reversed mechanical allodynia caused
by peripheral nerve injury in both male and female rats. Furthermore, targeting
Y382-384 suppressed P2X7R-mediated release of cytokine tumor
necrosis factor alpha and blocked the adoptive transfer of mechanical allodynia
caused by intrathecal injection of P2X7R-stimulated microglia. Thus,
Y382-384 site-specific modulation of P2X7R is an important
microglial mechanism in neuropathic pain.
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Affiliation(s)
- Rebecca Dalgarno
- 1 Department of Comparative Biology & Experimental Medicine, University of Calgary, Calgary, Alberta, Canada.,2 Department of Physiology & Pharmacology, University of Calgary, Calgary, Alberta, Canada.,3 Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Heather Leduc-Pessah
- 1 Department of Comparative Biology & Experimental Medicine, University of Calgary, Calgary, Alberta, Canada.,2 Department of Physiology & Pharmacology, University of Calgary, Calgary, Alberta, Canada.,3 Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Alexandra Pilapil
- 1 Department of Comparative Biology & Experimental Medicine, University of Calgary, Calgary, Alberta, Canada.,2 Department of Physiology & Pharmacology, University of Calgary, Calgary, Alberta, Canada.,3 Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Charlie Ht Kwok
- 1 Department of Comparative Biology & Experimental Medicine, University of Calgary, Calgary, Alberta, Canada.,2 Department of Physiology & Pharmacology, University of Calgary, Calgary, Alberta, Canada.,3 Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Tuan Trang
- 1 Department of Comparative Biology & Experimental Medicine, University of Calgary, Calgary, Alberta, Canada.,2 Department of Physiology & Pharmacology, University of Calgary, Calgary, Alberta, Canada.,3 Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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7
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Meijer M, Dörr B, Lammertse HC, Blithikioti C, van Weering JR, Toonen RF, Söllner TH, Verhage M. Tyrosine phosphorylation of Munc18-1 inhibits synaptic transmission by preventing SNARE assembly. EMBO J 2017; 37:300-320. [PMID: 29150433 PMCID: PMC5770875 DOI: 10.15252/embj.201796484] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 10/12/2017] [Accepted: 10/16/2017] [Indexed: 11/17/2022] Open
Abstract
Tyrosine kinases are important regulators of synaptic strength. Here, we describe a key component of the synaptic vesicle release machinery, Munc18‐1, as a phosphorylation target for neuronal Src family kinases (SFKs). Phosphomimetic Y473D mutation of a SFK phosphorylation site previously identified by brain phospho‐proteomics abolished the stimulatory effect of Munc18‐1 on SNARE complex formation (“SNARE‐templating”) and membrane fusion in vitro. Furthermore, priming but not docking of synaptic vesicles was disrupted in hippocampal munc18‐1‐null neurons expressing Munc18‐1Y473D. Synaptic transmission was temporarily restored by high‐frequency stimulation, as well as by a Munc18‐1 mutation that results in helix 12 extension, a critical conformational step in vesicle priming. On the other hand, expression of non‐phosphorylatable Munc18‐1 supported normal synaptic transmission. We propose that SFK‐dependent Munc18‐1 phosphorylation may constitute a potent, previously unknown mechanism to shut down synaptic transmission, via direct occlusion of a Synaptobrevin/VAMP2 binding groove and subsequent hindrance of conformational changes in domain 3a responsible for vesicle priming. This would strongly interfere with the essential post‐docking SNARE‐templating role of Munc18‐1, resulting in a largely abolished pool of releasable synaptic vesicles.
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Affiliation(s)
- Marieke Meijer
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam (NCA) VU University Medical Center, Amsterdam, The Netherlands
| | - Bernhard Dörr
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Hanna Ca Lammertse
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam (NCA) VU University Amsterdam, Amsterdam, The Netherlands
| | - Chrysanthi Blithikioti
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam (NCA) VU University Amsterdam, Amsterdam, The Netherlands
| | - Jan Rt van Weering
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam (NCA) VU University Medical Center, Amsterdam, The Netherlands
| | - Ruud Fg Toonen
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam (NCA) VU University Amsterdam, Amsterdam, The Netherlands
| | - Thomas H Söllner
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Matthijs Verhage
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam (NCA) VU University Medical Center, Amsterdam, The Netherlands .,Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam (NCA) VU University Amsterdam, Amsterdam, The Netherlands
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8
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Kohansal-Nodehi M, Chua JJ, Urlaub H, Jahn R, Czernik D. Analysis of protein phosphorylation in nerve terminal reveals extensive changes in active zone proteins upon exocytosis. eLife 2016; 5. [PMID: 27115346 PMCID: PMC4894758 DOI: 10.7554/elife.14530] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 04/25/2016] [Indexed: 12/31/2022] Open
Abstract
Neurotransmitter release is mediated by the fast, calcium-triggered fusion of synaptic vesicles with the presynaptic plasma membrane, followed by endocytosis and recycling of the membrane of synaptic vesicles. While many of the proteins governing these processes are known, their regulation is only beginning to be understood. Here we have applied quantitative phosphoproteomics to identify changes in phosphorylation status of presynaptic proteins in resting and stimulated nerve terminals isolated from the brains of Wistar rats. Using rigorous quantification, we identified 252 phosphosites that are either up- or downregulated upon triggering calcium-dependent exocytosis. Particularly pronounced were regulated changes of phosphosites within protein constituents of the presynaptic active zone, including bassoon, piccolo, and RIM1. Additionally, we have mapped kinases and phosphatases that are activated upon stimulation. Overall, our study provides a snapshot of phosphorylation changes associated with presynaptic activity and provides a foundation for further functional analysis of key phosphosites involved in presynaptic plasticity. DOI:http://dx.doi.org/10.7554/eLife.14530.001 The human nervous system contains more than a hundred billion neurons that are connected with each other via junctions called synapses. When an electrical impulse travelling along a neuron arrives at a synapse, it triggers bubble-like packages called synaptic vesicles within the neuron to merge with the neuron’s surface membrane. The contents of these vesicles – chemical messengers called neurotransmitters – are then released into the synapse and carry the signal to the next neuron. Complex molecular machines made from many different proteins control the release of neurotransmitters. Quite a few of these proteins are regulated by the addition of phosphate groups at specific sites. However, not all of the proteins involved in the release of neurotransmitters have been studied in detail and it is largely unclear how most of them are regulated. Now, Kohansal-Nodehi et al. have used techniques involving mass spectrometry to find out which proteins have phosphate groups added or removed in neurons that are releasing neurotransmitters. The experiments used pinched-off synapses isolated from rat brains. These structures, referred to as “synaptosomes”, lend themselves to this kind of study because they can be induced to continuously release neurotransmitters for several minutes. Kohansal-Nodehi et al. identified over 250 specific sites on proteins in the synaptosomes where phosphate groups are attached, including many on the key proteins known to operate in neurotransmitter release. Moreover, some proteins were modified at multiple sites, especially the proteins that form a scaffold to capture synaptic vesicles close to the membrane and prepare them for release. The data also revealed important clues about the enzymes that either attach or remove the phosphate groups. Together, these findings provide new insights into the regulatory networks that control many proteins at the same time. The next challenge is to sort out which of these modifications change the interactions between the proteins that control neurotransmitter release, and to understand how these changes influence the trafficking of synaptic vesicles. DOI:http://dx.doi.org/10.7554/eLife.14530.002
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Affiliation(s)
| | - John Je Chua
- Interactomics and Intracellular Trafficking laboratory, National University of Singapore, Singapore, Singapore.,Department of Physiology, National University of Singapore, Singapore, Singapore.,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Neurobiology/Ageing Programme, National University of Singapore, Singapore, Singapore
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.,Bioanalytics Group, University Medical Center Göttingen, Göttingen, Germany
| | - Reinhard Jahn
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Dominika Czernik
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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9
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Spring AM, Brusich DJ, Frank CA. C-terminal Src Kinase Gates Homeostatic Synaptic Plasticity and Regulates Fasciclin II Expression at the Drosophila Neuromuscular Junction. PLoS Genet 2016; 12:e1005886. [PMID: 26901416 PMCID: PMC4764653 DOI: 10.1371/journal.pgen.1005886] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 01/29/2016] [Indexed: 12/02/2022] Open
Abstract
Forms of homeostatic plasticity stabilize neuronal outputs and promote physiologically favorable synapse function. A well-studied homeostatic system operates at the Drosophila melanogaster larval neuromuscular junction (NMJ). At the NMJ, impairment of postsynaptic glutamate receptor activity is offset by a compensatory increase in presynaptic neurotransmitter release. We aim to elucidate how this process operates on a molecular level and is preserved throughout development. In this study, we identified a tyrosine kinase-driven signaling system that sustains homeostatic control of NMJ function. We identified C-terminal Src Kinase (Csk) as a potential regulator of synaptic homeostasis through an RNAi- and electrophysiology-based genetic screen. We found that Csk loss-of-function mutations impaired the sustained expression of homeostatic plasticity at the NMJ, without drastically altering synapse growth or baseline neurotransmission. Muscle-specific overexpression of Src Family Kinase (SFK) substrates that are negatively regulated by Csk also impaired NMJ homeostasis. Surprisingly, we found that transgenic Csk-YFP can support homeostatic plasticity at the NMJ when expressed either in the muscle or in the nerve. However, only muscle-expressed Csk-YFP was able to localize to NMJ structures. By immunostaining, we found that Csk mutant NMJs had dysregulated expression of the Neural Cell Adhesion Molecule homolog Fasciclin II (FasII). By immunoblotting, we found that levels of a specific isoform of FasII were decreased in homeostatically challenged GluRIIA mutant animals–but markedly increased in Csk mutant animals. Additionally, we found that postsynaptic overexpression of FasII from its endogenous locus was sufficient to impair synaptic homeostasis, and genetically reducing FasII levels in Csk mutants fully restored synaptic homeostasis. Based on these data, we propose that Csk and its SFK substrates impinge upon homeostatic control of NMJ function by regulating downstream expression or localization of FasII. Homeostasis is a fundamental topic in biology. Individual cells and systems of cells constantly monitor their environments and adjust their outputs in order to maintain physiological properties within ranges that can support life. The nervous system is no exception. Synapses and circuits are endowed with a capacity to respond to environmental challenges in a homeostatic fashion. As a result, synaptic output stays within an appropriate physiological range. We know that homeostasis is a fundamental form of regulation in animal nervous systems, but we have very little information about how it works. In this study, we examine the fruit fly Drosophila melanogaster and its ability to maintain normal levels of synaptic output over long periods of developmental time. We identify new roles in this process for classical signaling molecules called C-terminal Src kinase, Src family kinases, as well as a neuronal cell adhesion molecule called Fasciclin II, which was previously shown to stabilize synaptic contacts between neurons and muscles. Our work contributes to a broader understanding of how neurons work to maintain stable outputs. Ultimately, this type of knowledge could have important implications for neurological disorders in which stability is lost, such as forms of epilepsy or ataxia.
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Affiliation(s)
- Ashlyn M. Spring
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America
- Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, Iowa, United States of America
| | - Douglas J. Brusich
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America
| | - C. Andrew Frank
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America
- Interdisciplinary Programs in Genetics, Neuroscience, and MCB, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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10
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Zhao M, Wang T, Adamson KJ, Storey KB, Cummins SF. Multi-tissue transcriptomics for construction of a comprehensive gene resource for the terrestrial snail Theba pisana. Sci Rep 2016; 6:20685. [PMID: 26852673 PMCID: PMC4745086 DOI: 10.1038/srep20685] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 01/04/2016] [Indexed: 11/18/2022] Open
Abstract
The land snail Theba pisana is native to the Mediterranean region but has become one of the most abundant invasive species worldwide. Here, we present three transcriptomes of this agriculture pest derived from three tissues: the central nervous system, hepatopancreas (digestive gland), and foot muscle. Sequencing of the three tissues produced 339,479,092 high quality reads and a global de novo assembly generated a total of 250,848 unique transcripts (unigenes). BLAST analysis mapped 52,590 unigenes to NCBI non-redundant protein databases and further functional analysis annotated 21,849 unigenes with gene ontology. We report that T. pisana transcripts have representatives in all functional classes and a comparison of differentially expressed transcripts amongst all three tissues demonstrates enormous differences in their potential metabolic activities. The genes differentially expressed include those with sequence similarity to those genes associated with multiple bacterial diseases and neurological diseases. To provide a valuable resource that will assist functional genomics study, we have implemented a user-friendly web interface, ThebaDB (http://thebadb.bioinfo-minzhao.org/). This online database allows for complex text queries, sequence searches, and data browsing by enriched functional terms and KEGG mapping.
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Affiliation(s)
- M Zhao
- School of Engineering, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland, 4558, Australia
| | - T Wang
- School of Engineering, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland, 4558, Australia
| | - K J Adamson
- School of Engineering, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland, 4558, Australia
| | - K B Storey
- Institute of Biochemistry &Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - S F Cummins
- School of Engineering, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland, 4558, Australia
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11
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Siloni S, Singer-Lahat D, Esa M, Tsemakhovich V, Chikvashvili D, Lotan I. Regulation of the neuronal KCNQ2 channel by Src--a dual rearrangement of the cytosolic termini underlies bidirectional regulation of gating. J Cell Sci 2015; 128:3489-501. [PMID: 26275828 DOI: 10.1242/jcs.173922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 07/26/2015] [Indexed: 12/11/2022] Open
Abstract
Neuronal M-type K(+) channels are heteromers of KCNQ2 and KCNQ3 subunits, and are found in cell bodies, dendrites and the axon initial segment, regulating the firing properties of neurons. By contrast, presynaptic KCNQ2 homomeric channels directly regulate neurotransmitter release. Previously, we have described a mechanism for gating downregulation of KCNQ2 homomeric channels by calmodulin and syntaxin1A. Here, we describe a new mechanism for regulation of KCNQ2 channel gating that is modulated by Src, a non-receptor tyrosine kinase. In this mechanism, two concurrent distinct structural rearrangements of the cytosolic termini induce two opposing effects: upregulation of the single-channel open probability, mediated by an N-terminal tyrosine, and reduction in functional channels, mediated by a C-terminal tyrosine. In contrast, Src-mediated regulation of KCNQ3 homomeric channels, shown previously to be achieved through the corresponding tyrosine residues, involves the N-terminal-tyrosine-mediated downregulation of the open probability, rather than an upregulation. We argue that the dual bidirectional regulation of KCNQ2 functionality by Src, mediated through two separate sites, means that KCNQ2 can be modified by cellular factors that might specifically interact with either one of the sites, with potential significance in the fine-tuning of neurotransmitters release at nerve terminals.
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Affiliation(s)
- Sivan Siloni
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Ramat Aviv 69978, Israel
| | - Dafna Singer-Lahat
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Ramat Aviv 69978, Israel
| | - Moad Esa
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Ramat Aviv 69978, Israel
| | - Vlad Tsemakhovich
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Ramat Aviv 69978, Israel
| | - Dodo Chikvashvili
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Ramat Aviv 69978, Israel
| | - Ilana Lotan
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Ramat Aviv 69978, Israel
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12
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Cirnaru MD, Marte A, Belluzzi E, Russo I, Gabrielli M, Longo F, Arcuri L, Murru L, Bubacco L, Matteoli M, Fedele E, Sala C, Passafaro M, Morari M, Greggio E, Onofri F, Piccoli G. LRRK2 kinase activity regulates synaptic vesicle trafficking and neurotransmitter release through modulation of LRRK2 macro-molecular complex. Front Mol Neurosci 2014; 7:49. [PMID: 24904275 PMCID: PMC4034499 DOI: 10.3389/fnmol.2014.00049] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 05/09/2014] [Indexed: 11/13/2022] Open
Abstract
Mutations in Leucine-rich repeat kinase 2 gene (LRRK2) are associated with familial and sporadic Parkinson's disease (PD). LRRK2 is a complex protein that consists of multiple domains executing several functions, including GTP hydrolysis, kinase activity, and protein binding. Robust evidence suggests that LRRK2 acts at the synaptic site as a molecular hub connecting synaptic vesicles to cytoskeletal elements via a complex panel of protein-protein interactions. Here we investigated the impact of pharmacological inhibition of LRRK2 kinase activity on synaptic function. Acute treatment with LRRK2 inhibitors reduced the frequency of spontaneous currents, the rate of synaptic vesicle trafficking and the release of neurotransmitter from isolated synaptosomes. The investigation of complementary models lacking LRRK2 expression allowed us to exclude potential off-side effects of kinase inhibitors on synaptic functions. Next we studied whether kinase inhibition affects LRRK2 heterologous interactions. We found that the binding among LRRK2, presynaptic proteins and synaptic vesicles is affected by kinase inhibition. Our results suggest that LRRK2 kinase activity influences synaptic vesicle release via modulation of LRRK2 macro-molecular complex.
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Affiliation(s)
- Maria D Cirnaru
- Division of Neuroscience, San Raffaele Scientific Institute and Vita-Salute University Milan, Italy ; Department of Molecular and Cellular Pharmacology, National Research Council, Neuroscience Institute Milan, Italy
| | - Antonella Marte
- Department of Experimental Medicine, University of Genova Genova, Italy
| | - Elisa Belluzzi
- Department of Biology, University of Padova Padova, Italy
| | - Isabella Russo
- Department of Biology, University of Padova Padova, Italy
| | - Martina Gabrielli
- Department of Molecular and Cellular Pharmacology, National Research Council, Neuroscience Institute Milan, Italy ; Department of Medical Biotechnology and Translational Medicine, University of Milan Milan, Italy
| | - Francesco Longo
- Department of Medical Science and National Institute of Neuroscience, University of Ferrara Ferrara, Italy
| | - Ludovico Arcuri
- Department of Medical Science and National Institute of Neuroscience, University of Ferrara Ferrara, Italy
| | - Luca Murru
- Department of Molecular and Cellular Pharmacology, National Research Council, Neuroscience Institute Milan, Italy
| | - Luigi Bubacco
- Department of Biology, University of Padova Padova, Italy
| | - Michela Matteoli
- Department of Medical Biotechnology and Translational Medicine, University of Milan Milan, Italy ; Humanitas Clinical and Research Center, Pharmacology and Brain Pathology Rozzano, Italy
| | - Ernesto Fedele
- Department of Pharmacy, University of Genoa Genoa, Italy
| | - Carlo Sala
- Department of Molecular and Cellular Pharmacology, National Research Council, Neuroscience Institute Milan, Italy ; Department of Medical Biotechnology and Translational Medicine, University of Milan Milan, Italy
| | - Maria Passafaro
- Department of Molecular and Cellular Pharmacology, National Research Council, Neuroscience Institute Milan, Italy
| | - Michele Morari
- Department of Medical Science and National Institute of Neuroscience, University of Ferrara Ferrara, Italy
| | - Elisa Greggio
- Department of Biology, University of Padova Padova, Italy
| | - Franco Onofri
- Department of Experimental Medicine, University of Genova Genova, Italy
| | - Giovanni Piccoli
- Division of Neuroscience, San Raffaele Scientific Institute and Vita-Salute University Milan, Italy ; Department of Molecular and Cellular Pharmacology, National Research Council, Neuroscience Institute Milan, Italy
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13
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Giovedí S, Corradi A, Fassio A, Benfenati F. Involvement of synaptic genes in the pathogenesis of autism spectrum disorders: the case of synapsins. Front Pediatr 2014; 2:94. [PMID: 25237665 PMCID: PMC4154395 DOI: 10.3389/fped.2014.00094] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 08/21/2014] [Indexed: 12/03/2022] Open
Abstract
Autism spectrum disorders (ASDs) are heterogeneous neurodevelopmental disorders characterized by deficits in social interaction and social communication, restricted interests, and repetitive behaviors. Many synaptic protein genes are linked to the pathogenesis of ASDs, making them prototypical synaptopathies. An array of mutations in the synapsin (Syn) genes in humans has been recently associated with ASD and epilepsy, diseases that display a frequent comorbidity. Syns are pre-synaptic proteins regulating synaptic vesicle traffic, neurotransmitter release, and short-term synaptic plasticity. In doing so, Syn isoforms control the tone of activity of neural circuits and the balance between excitation and inhibition. As ASD pathogenesis is believed to result from dysfunctions in the balance between excitatory and inhibitory transmissions in neocortical areas, Syns are novel ASD candidate genes. Accordingly, deletion of single Syn genes in mice, in addition to epilepsy, causes core symptoms of ASD by affecting social behavior, social communication, and repetitive behaviors. Thus, Syn knockout mice represent a good experimental model to define synaptic alterations involved in the pathogenesis of ASD and epilepsy.
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Affiliation(s)
- Silvia Giovedí
- Department of Experimental Medicine, University of Genova , Genova , Italy
| | - Anna Corradi
- Department of Experimental Medicine, University of Genova , Genova , Italy
| | - Anna Fassio
- Department of Experimental Medicine, University of Genova , Genova , Italy ; Department of Neuroscience and Brain Technologies, Fondazione Istituto Italiano di Tecnologia , Genova , Italy
| | - Fabio Benfenati
- Department of Experimental Medicine, University of Genova , Genova , Italy ; Department of Neuroscience and Brain Technologies, Fondazione Istituto Italiano di Tecnologia , Genova , Italy
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14
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Mallozzi C, D'Amore C, Camerini S, Macchia G, Crescenzi M, Petrucci TC, Di Stasi AMM. Phosphorylation and nitration of tyrosine residues affect functional properties of Synaptophysin and Dynamin I, two proteins involved in exo-endocytosis of synaptic vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:110-21. [DOI: 10.1016/j.bbamcr.2012.10.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 10/08/2012] [Accepted: 10/21/2012] [Indexed: 12/14/2022]
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15
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Inhibition of presynaptic Na(+)/K(+)-ATPase reduces readily releasable pool size at the avian end-bulb of Held synapse. Neurosci Res 2011; 72:117-28. [PMID: 22100365 DOI: 10.1016/j.neures.2011.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 10/09/2011] [Accepted: 11/04/2011] [Indexed: 11/23/2022]
Abstract
A glutamatergic end-bulb synapse in the avian nucleus magnocellularis relays temporal sound information from the auditory nerve. Here, we show that presynaptic Na(+)/K(+)-ATPase (NKA) activity at this synapse contributes to the maintenance of the readily releasable pool (RRP) of vesicles, thereby preserving synaptic strength. Whole-cell voltage clamp recordings were made from chick brainstem slices to examine the effects of NKA blocker dihydroouabain (DHO) on synaptic transmission. DHO suppressed the amplitude of EPSCs in a dose-dependent manner. This suppression was caused by a decrease in the number of neurotransmitter quanta released because DHO increased the coefficient of variation of EPSC amplitude and reduced the frequency but not the amplitude of miniature EPSCs. Cumulative plots of EPSC amplitude during a stimulus train revealed that DHO reduced the RRP size without affecting vesicular release probability. DHO did not affect [Ca(2+)](i)-dependent processes, such as the paired-pulse ratio or recovery time course from the paired-pulse depression, suggesting a minimal effect on Ca(2+) concentration in the presynaptic terminal. Using mathematical models of synaptic depression, we further demonstrated the contribution of RRP size to the synaptic strength during a high-frequency stimulus train to highlight the importance of presynaptic NKA in the auditory synapse.
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16
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Valtorta F, Pozzi D, Benfenati F, Fornasiero EF. The synapsins: multitask modulators of neuronal development. Semin Cell Dev Biol 2011; 22:378-86. [PMID: 21798361 DOI: 10.1016/j.semcdb.2011.07.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 07/13/2011] [Indexed: 01/10/2023]
Abstract
Neurons are examples of specialized cells that evolved the extraordinary ability to transmit electrochemical information in complex networks of interconnected cells. During their development, neurons undergo precisely regulated processes that define their lineage, positioning, morphogenesis and pattern of activity. The events leading to the establishment of functional neuronal networks follow a number of key steps, including asymmetric cell division from neuronal precursors, migration, establishment of polarity, neurite outgrowth and synaptogenesis. Synapsins are a family of abundant neuronal phosphoproteins that have been extensively studied for their role in the regulation of neurotransmission in presynaptic terminals. Beside their implication in the homeostasis of adult cells, synapsins influence the development of young neurons, interacting with cytoskeletal and vesicular components and regulating their dynamics. Although the exact molecular mechanisms determining synapsin function in neuronal development are still largely unknown, in this review we summarize the most important literature on the subject, providing a conceptual framework for the progress of present and future research.
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Affiliation(s)
- Flavia Valtorta
- San Raffaele Scientific Institute and Vita-Salute University, Via Olgettina 58, Milano, Italy.
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17
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Humeau Y, Candiani S, Ghirardi M, Poulain B, Montarolo P. Functional roles of synapsin: Lessons from invertebrates. Semin Cell Dev Biol 2011; 22:425-33. [DOI: 10.1016/j.semcdb.2011.07.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 07/13/2011] [Indexed: 12/18/2022]
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18
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Shupliakov O, Haucke V, Pechstein A. How synapsin I may cluster synaptic vesicles. Semin Cell Dev Biol 2011; 22:393-9. [DOI: 10.1016/j.semcdb.2011.07.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 07/13/2011] [Indexed: 12/14/2022]
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19
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Zeng HC, Li YY, Zhang L, Wang YJ, Chen J, Xia W, Lin Y, Wei J, Lv ZQ, Li M, Xu SQ. Prenatal exposure to perfluorooctanesulfonate in rat resulted in long-lasting changes of expression of synapsins and synaptophysin. Synapse 2011; 65:225-33. [PMID: 20687110 DOI: 10.1002/syn.20840] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Both animal and human studies have demonstrated that exposure to chemical pollutants during critical developmental period causes adverse consequences later in life. In uterus, perfluorooctanesulfonate (PFOS) exposure has been known to cause developmental neurotoxicity, such as increased motor activity, reduced habitation and impaired cognitive function. The possible mechanism of the impaired cognitive function induced by prenatal PFOS exposure was evaluated in this study. Pregnant Sprague Dawley (SD) rats were given 0.1, 0.6, and 2.0 mg kg(-1) birth weight (bw) d(-1) by gavage from gestation day (GD) 0 to GD20. Control received 0.5% Tween-20 vehicle (4 ml kg(-1) bw d(-1)). PFOS concentration in hippocampus of offspring was observed on postnatal day (PND) 0 and PND21. The ultrastructure of hippocampus and the gene expression of synaptic vesicle associated proteins in offspring hippocampus, which were important for the neurotransmitter release, were investigated. The transmission electron photomicrographs of the offspring hippocampus from PFOS-treated maternal groups showed the ultrastructure of synapses was negatively affected. The offspring from PFOS-treated maternal groups also differed significantly from controls with respect to the expression of synaptic vesicle associated proteins. The mRNA levels of synapsin1 (Syn1), synapsin2 (Syn2), and synaptophysin (Syp) were decreased in treated groups either on PND0 or on PND21. However, the mRNA level of synapsin3 (Syn3) decreased in 0.6- and 2.0-mg kg(-1) group on PND0, and showed no significant difference among control group and all treated groups on PND21. These results indicate that the impairment of cognitive function induced by PFOS may be attributed to the lower mRNA levels of synaptic vesicle associated proteins and the change of synaptic ultrastructure in hippocampus.
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Affiliation(s)
- Huai-Cai Zeng
- Ministry of Education Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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Abstract
We report here that the Src family tyrosine kinase Lyn negatively regulates the release of dopamine (DA) in the mesolimbic system, as well as the rewarding properties of alcohol. Specifically, we show that RNA interference-mediated knockdown of Lyn expression results in an increase in KCl-induced DA release in DAergic-like SH-SY5Y cells, whereas overexpression of a constitutively active form of Lyn (CA-Lyn) leads to a decrease of DA release. Activation of ventral tegmental area (VTA) DAergic neurons results in DA overflow in the nucleus accumbens (NAc), and we found that the evoked release of DA was higher in the NAc of Lyn knock-out (Lyn KO) mice compared with wild-type littermate (Lyn WT) controls. Acute exposure of rodents to alcohol causes a rapid increase in DA release in the NAc, and we show that overexpression of CA-Lyn in the VTA of mice blocked alcohol-induced (2 g/kg) DA release in the NAc. Increase in DA levels in the NAc is closely associated with reward-related behaviors, and overexpression of CA-Lyn in the VTA of mice led to an attenuation of alcohol reward, measured in a conditioned place preference paradigm. Conversely, alcohol place preference was increased in Lyn KO mice compared with Lyn WT controls. Together, our results suggest a novel role for Lyn kinase in the regulation of DA release in the mesolimbic system, which leads to the control of alcohol reward.
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Estradiol acutely potentiates hippocampal excitatory synaptic transmission through a presynaptic mechanism. J Neurosci 2011; 30:16137-48. [PMID: 21123560 DOI: 10.1523/jneurosci.4161-10.2010] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Although recent evidence suggests that the hippocampus is a source of 17β-estradiol (E2), the physiological role of this neurosteroid E2, as distinct from ovarian E2, is unknown. One likely function of neurosteroid E2 is to acutely potentiate excitatory synaptic transmission, but the mechanism of this effect is not well understood. Using whole-cell voltage-clamp recording of synaptically evoked EPSCs in adult rat hippocampal slices, we show that, in contrast to the conclusions of previous studies, E2 potentiates excitatory transmission through a presynaptic mechanism. We find that E2 acutely potentiates EPSCs by increasing the probability of glutamate release specifically at inputs with low initial release probability. This effect is mediated by estrogen receptor β (ERβ) acting as a monomer, whereas ERα is not required. We further show that the E2-induced increase in glutamate release is attributable primarily to increased individual vesicle release probability and is associated with higher average cleft glutamate concentration. These two findings together argue strongly that E2 promotes multivesicular release, which has not been shown before in the adult hippocampus. The rapid time course of acute EPSC potentiation and its concentration dependence suggest that locally synthesized neurosteroid E2 may activate this effect in vivo.
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Nuwal T, Heo S, Lubec G, Buchner E. Mass spectrometric analysis of synapsins in Drosophila melanogaster and identification of novel phosphorylation sites. J Proteome Res 2010; 10:541-50. [PMID: 21028912 DOI: 10.1021/pr100746s] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Synapsins are synaptic vesicle-associated phosphoproteins that play a major role in the fine regulation of neurotransmitter release. In Drosophila, synapsins are required for complex behavior including learning and memory. Synapsin isoforms were immunoprecipitated from homogenates of wild-type Drosophila heads using monoclonal antibody 3C11. Synapsin null mutants (Syn(97)) served as negative controls. The eluted proteins were separated by SDS-PAGE and visualized by silver staining. Gel pieces picked from five bands specific for wild type were analyzed by nano-LC-ESI-MS/MS following multienzyme digestion (trypsin, chymotrypsin, AspN, subtilisin, pepsin, and proteinase K). The protein was unambiguously identified with high sequence coverage (90.83%). A number of sequence conflicts were observed and the N-terminal amino acid was identified as methionine rather than leucine expected from the cDNA sequence. Several peptides from the larger isoform demonstrated that the in-frame UAG stop codon at position 582 which separates two large open reading frames is read through by tRNAs for lysine. Seven novel phosphorylation sites in Drosophila synapsin were identified at Thr-86, Ser-87, Ser-464, Thr-466, Ser-538, Ser-961, and Tyr-982 and verified by phosphatase treatment. No phosphorylation was observed at the conserved PKA/CaM kinase-I/IV site (RRFS, edited to RGFS) in domain A or a potential PKA site near domain E.
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Affiliation(s)
- Tulip Nuwal
- Department of Neurobiology and Genetics, Biozentrum, University of Wuerzburg, Wuerzburg, Germany
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De Franchi E, Schalon C, Messa M, Onofri F, Benfenati F, Rognan D. Binding of protein kinase inhibitors to synapsin I inferred from pair-wise binding site similarity measurements. PLoS One 2010; 5:e12214. [PMID: 20808948 PMCID: PMC2922380 DOI: 10.1371/journal.pone.0012214] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Accepted: 07/26/2010] [Indexed: 11/18/2022] Open
Abstract
Predicting off-targets by computational methods is getting increasing importance in early drug discovery stages. We herewith present a computational method based on binding site three-dimensional comparisons, which prompted us to investigate the cross-reaction of protein kinase inhibitors with synapsin I, an ATP-binding protein regulating neurotransmitter release in the synapse. Systematic pair-wise comparison of the staurosporine-binding site of the proto-oncogene Pim-1 kinase with 6,412 druggable protein-ligand binding sites suggested that the ATP-binding site of synapsin I may recognize the pan-kinase inhibitor staurosporine. Biochemical validation of this hypothesis was realized by competition experiments of staurosporine with ATP-gamma(35)S for binding to synapsin I. Staurosporine, as well as three other inhibitors of protein kinases (cdk2, Pim-1 and casein kinase type 2), effectively bound to synapsin I with nanomolar affinities and promoted synapsin-induced F-actin bundling. The selective Pim-1 kinase inhibitor quercetagetin was shown to be the most potent synapsin I binder (IC50 = 0.15 microM), in agreement with the predicted binding site similarities between synapsin I and various protein kinases. Other protein kinase inhibitors (protein kinase A and chk1 inhibitor), kinase inhibitors (diacylglycerolkinase inhibitor) and various other ATP-competitors (DNA topoisomerase II and HSP-90alpha inhibitors) did not bind to synapsin I, as predicted from a lower similarity of their respective ATP-binding sites to that of synapsin I. The present data suggest that the observed downregulation of neurotransmitter release by some but not all protein kinase inhibitors may also be contributed by a direct binding to synapsin I and phosphorylation-independent perturbation of synapsin I function. More generally, the data also demonstrate that cross-reactivity with various targets may be detected by systematic pair-wise similarity measurement of ligand-annotated binding sites.
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Affiliation(s)
- Enrico De Franchi
- Department of Neuroscience and Brain Technologies, The Italian Institute of Technology, Genova, Italy
| | - Claire Schalon
- Structural Chemogenomics, Laboratory of Therapeutic Innovation, CNRS UMR 7200, Université de Strasbourg, Illkirch, France
| | - Mirko Messa
- Department of Neuroscience and Brain Technologies, The Italian Institute of Technology, Genova, Italy
| | - Franco Onofri
- Department of Experimental Medicine, University of Genova and Istituto Nazionale di Neuroscienze, Genova, Italy
| | - Fabio Benfenati
- Department of Neuroscience and Brain Technologies, The Italian Institute of Technology, Genova, Italy
- Department of Experimental Medicine, University of Genova and Istituto Nazionale di Neuroscienze, Genova, Italy
| | - Didier Rognan
- Structural Chemogenomics, Laboratory of Therapeutic Innovation, CNRS UMR 7200, Université de Strasbourg, Illkirch, France
- * E-mail:
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24
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Messa M, Congia S, Defranchi E, Valtorta F, Fassio A, Onofri F, Benfenati F. Tyrosine phosphorylation of synapsin I by Src regulates synaptic-vesicle trafficking. J Cell Sci 2010; 123:2256-65. [PMID: 20530578 DOI: 10.1242/jcs.068445] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Synapsins are synaptic vesicle (SV)-associated phosphoproteins involved in the regulation of neurotransmitter release. Synapsins reversibly tether SVs to the cytoskeleton and their phosphorylation by serine/threonine kinases increases SV availability for exocytosis by impairing their association with SVs and/or actin. We recently showed that synapsin I, through SH3- or SH2-mediated interactions, activates Src and is phosphorylated by the same kinase at Tyr301. Here, we demonstrate that, in contrast to serine phosphorylation, Src-mediated tyrosine phosphorylation of synapsin I increases its binding to SVs and actin, and increases the formation of synapsin dimers, which are both potentially involved in SV clustering. Synapsin I phosphorylation by Src affected SV dynamics and was physiologically regulated in brain slices in response to depolarization. Expression of the non-phosphorylatable (Y301F) synapsin I mutant in synapsin-I-knockout neurons increased the sizes of the readily releasable and recycling pools of SVs with respect to the wild-type form, which is consistent with an increased availability of recycled SVs for exocytosis. The data provide a mechanism for the effects of Src on SV trafficking and indicate that tyrosine phosphorylation of synapsins, unlike serine phosphorylation, stimulates the reclustering of recycled SVs and their recruitment to the reserve pool.
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Affiliation(s)
- Mirko Messa
- Department of Experimental Medicine, University of Genova and Istituto Nazionale di Neuroscienze, Viale Benedetto XV 3, 161632 Genova, Italy
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Fornasiero EF, Bonanomi D, Benfenati F, Valtorta F. The role of synapsins in neuronal development. Cell Mol Life Sci 2010; 67:1383-96. [PMID: 20035364 PMCID: PMC11115787 DOI: 10.1007/s00018-009-0227-8] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Revised: 11/22/2009] [Accepted: 12/04/2009] [Indexed: 12/23/2022]
Abstract
The synapsins, the first identified synaptic vesicle-specific proteins, are phosphorylated on multiple sites by a number of protein kinases and are involved in neurite outgrowth and synapse formation as well as in synaptic transmission. In mammals, the synapsin family consists of at least 10 isoforms encoded by 3 distinct genes and composed by a mosaic of conserved and variable domains. The synapsins are highly conserved evolutionarily, and orthologues have been found in invertebrates and lower vertebrates. Within nerve terminals, synapsins are implicated in multiple interactions with presynaptic proteins and the actin cytoskeleton. Via these interactions, synapsins control several mechanisms important for neuronal homeostasis. In this review, we describe the main functional features of the synapsins, in relation to the complex role played by these phosphoproteins in neuronal development.
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Affiliation(s)
- Eugenio F. Fornasiero
- San Raffaele Scientific Institute, Vita-Salute University, Via Olgettina 58, 20132 Milan, Italy
- Unit of Molecular Neuroscience, The Italian Institute of Technology, Via Olgettina 58, 20132 Milan, Italy
| | - Dario Bonanomi
- San Raffaele Scientific Institute, Vita-Salute University, Via Olgettina 58, 20132 Milan, Italy
- Present Address: Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA 92037 USA
- Unit of Molecular Neuroscience, The Italian Institute of Technology, Via Olgettina 58, 20132 Milan, Italy
| | - Fabio Benfenati
- Department of Neuroscience and Brain Technologies, The Italian Institute of Technology, Via Morego 30, 16163 Genoa, Italy
- Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genoa, Italy
| | - Flavia Valtorta
- San Raffaele Scientific Institute, Vita-Salute University, Via Olgettina 58, 20132 Milan, Italy
- Unit of Molecular Neuroscience, The Italian Institute of Technology, Via Olgettina 58, 20132 Milan, Italy
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Candiani S, Moronti L, Pennati R, De Bernardi F, Benfenati F, Pestarino M. The synapsin gene family in basal chordates: evolutionary perspectives in metazoans. BMC Evol Biol 2010; 10:32. [PMID: 20113475 PMCID: PMC2825198 DOI: 10.1186/1471-2148-10-32] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 01/29/2010] [Indexed: 01/07/2023] Open
Abstract
Background Synapsins are neuronal phosphoproteins involved in several functions correlated with both neurotransmitter release and synaptogenesis. The comprehension of the basal role of the synapsin family is hampered in vertebrates by the existence of multiple synapsin genes. Therefore, studying homologous genes in basal chordates, devoid of genome duplication, could help to achieve a better understanding of the complex functions of these proteins. Results In this study we report the cloning and characterization of the Ciona intestinalis and amphioxus Branchiostoma floridae synapsin transcripts and the definition of their gene structure using available C. intestinalis and B. floridae genomic sequences. We demonstrate the occurrence, in both model organisms, of a single member of the synapsin gene family. Full-length synapsin genes were identified in the recently sequenced genomes of phylogenetically diverse metazoans. Comparative genome analysis reveals extensive conservation of the SYN locus in several metazoans. Moreover, developmental expression studies underline that synapsin is a neuronal-specific marker in basal chordates and is expressed in several cell types of PNS and in many, if not all, CNS neurons. Conclusion Our study demonstrates that synapsin genes are metazoan genes present in a single copy per genome, except for vertebrates. Moreover, we hypothesize that, during the evolution of synapsin proteins, new domains are added at different stages probably to cope up with the increased complexity in the nervous system organization. Finally, we demonstrate that protochordate synapsin is restricted to the post-mitotic phase of CNS development and thereby is a good marker of postmitotic neurons.
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Affiliation(s)
- Simona Candiani
- Department of Biology, University of Genoa, Viale Benedetto XV5, 16132 Genova, Italy.
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The highly conserved synapsin domain E mediates synapsin dimerization and phospholipid vesicle clustering. Biochem J 2010; 426:55-64. [PMID: 19922412 DOI: 10.1042/bj20090762] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Synapsins are abundant SV (synaptic vesicle)-associated phosphoproteins that regulate synapse formation and function. The highly conserved C-terminal domain E was shown to contribute to several synapsin functions, ranging from formation of the SV reserve pool to regulation of the kinetics of exocytosis and SV cycling, although the molecular mechanisms underlying these effects are unknown. In the present study, we used a synthetic 25-mer peptide encompassing the most conserved region of domain E (Pep-E) to analyse the role of domain E in regulating the interactions between synapsin I and liposomes mimicking the phospholipid composition of SVs (SV-liposomes) and other pre-synaptic protein partners. In affinity-chromatography and cross-linking assays, Pep-E bound to endogenous and purified exogenous synapsin I and strongly inhibited synapsin dimerization, indicating a role in synapsin oligomerization. Consistently, Pep-E (but not its scrambled version) counteracted the ability of holo-synapsin I to bind and coat phospholipid membranes, as analysed by AFM (atomic force microscopy) topographical scanning, and significantly decreased the clustering of SV-liposomes induced by holo-synapsin I in FRET (Förster resonance energy transfer) assays, suggesting a causal relationship between synapsin oligomerization and vesicle clustering. Either Pep-E or a peptide derived from domain C was necessary and sufficient to inhibit both dimerization and vesicle clustering, indicating the participation of both domains in these activities of synapsin I. The results provide a molecular explanation for the effects of domain E in nerve terminal physiology and suggest that its effects on the size and integrity of SV pools are contributed by the regulation of synapsin dimerization and SV clustering.
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Patil SS, Schlick F, Höger H, Lubec G. Involvement of individual hippocampal signaling protein levels in spatial memory formation is strain-dependent. Amino Acids 2009; 39:75-87. [PMID: 19890699 DOI: 10.1007/s00726-009-0379-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Accepted: 10/14/2009] [Indexed: 12/30/2022]
Abstract
Although a series of signaling cascades involved in spatial memory have been identified, their link to spatial memory and strain-dependent expression has not been reported so far. Hippocampal levels of the abovementioned signaling proteins were determined in laboratory inbred strain C57BL/6J, the wild-derived inbred strain PWD/PhJ and the wild caught mouse Apodemus sylvaticus (AS) by immunoblotting. The resulting hippocampal protein levels were correlated with results from MWM. Hippocampal signaling protein (hSP) levels were tested also in yoked controls. Within-strain comparison between trained and yoked controls revealed significant differences between levels of Phospho-CaMKII (alpha), Phospho-CREB, Egr-1, c-Src, Phospho-ERK5, Phospho-MEK5 and NOS1 in all of the three strains tested. In addition, the three strains revealed different involvement of individual hSP levels clearly indicating that individual mouse strains were linked to individual hSPs in spatial memory. Phospho-ERK5 levels were not detectable in hippocampi of yoked controls of each strain. We learn from this study that a series of hSPs are associated with spatial memory and that different hSPs are linked to spatial memory in different strains that show different outcome in the MWM. Even correlational patterns in the individual hSPs differed between mouse strains. This is of importance for the interpretation of previous studies on the abovementioned signaling cascades as well as for the design of future studies on these hippocampal proteins. It is intriguing that individual mouse strains, laboratory or wild caught, may use different signaling pathways for spatial memory in the Morris water maze.
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Affiliation(s)
- Sudarshan S Patil
- Division of Pediatric Neuroscience, Department of Pediatrics, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria
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Calabrese V, Cornelius C, Rizzarelli E, Owen JB, Dinkova-Kostova AT, Butterfield DA. Nitric oxide in cell survival: a janus molecule. Antioxid Redox Signal 2009; 11:2717-39. [PMID: 19558211 DOI: 10.1089/ars.2009.2721] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Nitric oxide (NO), plays multiple roles in the nervous system. In addition to regulating proliferation, survival and differentiation of neurons, NO is involved in synaptic activity, neural plasticity, and memory function. Nitric oxide promotes survival and differentiation of neural cells and exerts long-lasting effects through regulation of transcription factors and modulation of gene expression. Signaling by reactive nitrogen species is carried out mainly by targeted modifications of critical cysteine residues in proteins, including S-nitrosylation and S-oxidation, as well as by lipid nitration. NO and other reactive nitrogen species are also involved in neuroinflammation and neurodegeneration, such as in Alzheimer disease, amyotrophic lateral sclerosis, Parkinson disease, multiple sclerosis, Friedreich ataxia, and Huntington disease. Susceptibility to NO and peroxynitrite exposure may depend on factors such as the intracellular reduced glutathione and cellular stress resistance signaling pathways. Thus, neurons, in contrast to astrocytes, appear particularly vulnerable to the effects of nitrosative stress. This article reviews the current understanding of the cytotoxic versus cytoprotective effects of NO in the central nervous system, highlighting the Janus-faced properties of this small molecule. The significance of NO in redox signaling and modulation of the adaptive cellular stress responses and its exciting future perspectives also are discussed.
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Affiliation(s)
- Vittorio Calabrese
- Department of Chemistry, Biochemistry and Molecular Biology Section, Faculty of Medicine, University of Catania , Catania, Italy.
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Mallozzi C, Ceccarini M, Camerini S, Macchia G, Crescenzi M, Petrucci TC, Di Stasi AMM. Peroxynitrite induces tyrosine residue modifications in synaptophysin C-terminal domain, affecting its interaction with src. J Neurochem 2009; 111:859-69. [PMID: 19737347 DOI: 10.1111/j.1471-4159.2009.06378.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Peroxynitrite is a potent oxidant that contributes to tissue damage in neurodegenerative disorders. We have previously reported that treatment of rat brain synaptosomes with peroxynitrite induced post-translational modifications in pre- and post-synaptic proteins and stimulated soluble N-ethylmaleimide sensitive fusion proteins attachment receptor complex formation and endogenous glutamate release. In this study we show that, following peroxynitrite treatment, the synaptic vesicle protein synaptophysin (SYP) can be both phosphorylated and nitrated in a dose-dependent manner. We found that tyrosine-phosphorylated, but not tyrosine-nitrated, SYP bound to the src tyrosine kinase and enhanced its catalytic activity. These effects were mediated by direct and specific binding of the SYP cytoplasmic C-terminal tail with the src homology 2 domain. Using mass spectrometry analysis, we mapped the SYP C-terminal tail tyrosine residues modified by peroxynitrite and found one nitration site at Tyr250 and two phosphorylation sites at Tyr263 and Tyr273. We suggest that peroxynitrite-mediated modifications of SYP may be relevant in modulating src signalling of synaptic terminal in pathophysiological conditions.
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Affiliation(s)
- Cinzia Mallozzi
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena, Rome, Italy
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Reed TT, Owen J, Pierce WM, Sebastian A, Sullivan PG, Butterfield DA. Proteomic identification of nitrated brain proteins in traumatic brain-injured rats treated postinjury with gamma-glutamylcysteine ethyl ester: Insights into the role of elevation of glutathione as a potential therapeutic strategy for traumatic brain injury. J Neurosci Res 2009; 87:408-17. [DOI: 10.1002/jnr.21872] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Abstract
Homogenization of fresh brain tissue in isotonic medium shears plasma membranes causing nerve terminals to become separated from their axons and postsynaptic connections. The nerve terminal membranes then reseal to form synaptosomes. The discontinuous Percoll gradient procedure described here is designed to isolate synaptosomes from brain homogenates in the minimum time to allow functional experiments to be performed. Synaptosomes are isolated using a medium-speed centrifuge, while maintaining isotonic conditions and minimizing mechanically damaging resuspension steps. This protocol has advantages over other procedures in terms of speed and by producing relatively homogeneous synaptosomes, minimizing the presence of synaptic and glial plasma membranes and extrasynaptosomal mitochondria. The purified synaptosomes are viable and take up and release neurotransmitters very efficiently. A typical yield of synaptosomes is between 2.5 and 4 mg of synaptosomal protein per gram rat brain. The procedure takes approximately 1 h from homogenization of the brain until collection of the synaptosomal suspension from the Percoll gradient.
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Hofbauer A, Ebel T, Waltenspiel B, Oswald P, Chen YC, Halder P, Biskup S, Lewandrowski U, Winkler C, Sickmann A, Buchner S, Buchner E. The Wuerzburg hybridoma library against Drosophila brain. J Neurogenet 2009; 23:78-91. [PMID: 19132598 DOI: 10.1080/01677060802471627] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
This review describes the present state of a project to identify and characterize novel nervous system proteins by using monoclonal antibodies (mAbs) against the Drosophila brain. Some 1,000 hybridoma clones were generated by injection of homogenized Drosophila brains or heads into mice and fusion of their spleen cells with myeloma cells. Testing the mAbs secreted by these clones identified a library of about 200 mAbs, which selectively stain specific structures of the Drosophila brain. Using the approach "from antibody to gene", several genes coding for novel proteins of the presynaptic terminal were cloned and characterized. These include the "cysteine string protein" gene (Csp, mAb ab49), the "synapse-associated protein of 47 kDa" gene (Sap47, mAbs nc46 and nb200), and the "Bruchpilot" gene (brp, mAb nc82). By a "candidate" approach, mAb nb33 was shown to recognize the pigment dispersing factor precursor protein. mAbs 3C11 and pok13 were raised against bacterially expressed Drosophila synapsin and calbindin-32, respectively, after the corresponding cDNAs had been isolated from an expression library by using antisera against mammalian proteins. Recently, it was shown that mAb aa2 binds the Drosophila homolog of "epidermal growth factor receptor pathway substrate clone 15" (Eps15). Identification of the targets of mAbs na21, ab52, and nb181 is presently attempted. Here, we review the available information on the function of these proteins and present staining patterns in the Drosophila brain for classes of mAbs that either bind differentially in the eye, in neuropil, in the cell-body layer, or in small subsets of neurons. The prospects of identifying the corresponding antigens by various approaches, including protein purification and mass spectrometry, are discussed.
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Affiliation(s)
- Alois Hofbauer
- Institut für Zoologie, Lehrstuhl für Entwicklungsbiologie, Regensburg, Germany.
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