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Stavsky A, Parra-Rivas LA, Tal S, Riba J, Madhivanan K, Roy S, Gitler D. Synapsin E-domain is essential for α-synuclein function. eLife 2024; 12:RP89687. [PMID: 38713200 PMCID: PMC11076041 DOI: 10.7554/elife.89687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024] Open
Abstract
The cytosolic proteins synucleins and synapsins are thought to play cooperative roles in regulating synaptic vesicle (SV) recycling, but mechanistic insight is lacking. Here, we identify the synapsin E-domain as an essential functional binding-partner of α-synuclein (α-syn). Synapsin E-domain allows α-syn functionality, binds to α-syn, and is necessary and sufficient for enabling effects of α-syn at synapses of cultured mouse hippocampal neurons. Together with previous studies implicating the E-domain in clustering SVs, our experiments advocate a cooperative role for these two proteins in maintaining physiologic SV clusters.
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Affiliation(s)
- Alexandra Stavsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences and School of Brain Sciences and Cognition, Ben-Gurion University of the NegevBeer ShevaIsrael
| | - Leonardo A Parra-Rivas
- Department of Pathology, University of California, San DiegoLa JollaUnited States
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research NetworkChevy ChaseUnited States
| | - Shani Tal
- Department of Physiology and Cell Biology, Faculty of Health Sciences and School of Brain Sciences and Cognition, Ben-Gurion University of the NegevBeer ShevaIsrael
| | - Jen Riba
- Department of Physiology and Cell Biology, Faculty of Health Sciences and School of Brain Sciences and Cognition, Ben-Gurion University of the NegevBeer ShevaIsrael
| | | | - Subhojit Roy
- Department of Pathology, University of California, San DiegoLa JollaUnited States
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research NetworkChevy ChaseUnited States
- Department of Neurosciences, University of California, San DiegoLa JollaUnited States
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences and School of Brain Sciences and Cognition, Ben-Gurion University of the NegevBeer ShevaIsrael
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Stavsky A, Parra-Rivas LA, Tal S, Riba J, Madhivanan K, Roy S, Gitler D. Synapsin E-domain is essential for α-synuclein function. bioRxiv 2023:2023.06.24.546170. [PMID: 37425805 PMCID: PMC10327093 DOI: 10.1101/2023.06.24.546170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
The cytosolic proteins synucleins and synapsins are thought to play cooperative roles in regulating synaptic vesicle (SV) recycling, but mechanistic insight is lacking. Here we identify the synapsin E-domain as an essential functional binding-partner of α-synuclein (α-syn). Synapsin E-domain allows α-syn functionality, binds to α-syn, and is necessary and sufficient for enabling effects of α-syn at the synapse. Together with previous studies implicating the E-domain in clustering SVs, our experiments advocate a cooperative role for these two proteins in maintaining physiologic SV clusters.
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Affiliation(s)
- Alexandra Stavsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences and School of Brain Sciences and Cognition, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Leonardo A. Parra-Rivas
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD, 20815
| | - Shani Tal
- Department of Physiology and Cell Biology, Faculty of Health Sciences and School of Brain Sciences and Cognition, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Jen Riba
- Department of Physiology and Cell Biology, Faculty of Health Sciences and School of Brain Sciences and Cognition, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Kayalvizhi Madhivanan
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
- Current address: Arrowhead Pharmaceuticals, Pasadena, CA, 91105
| | - Subhojit Roy
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
- Department of Neurosciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD, 20815
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences and School of Brain Sciences and Cognition, Ben-Gurion University of the Negev, Beer Sheva, Israel
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Bakavayev S, Stavsky A, Argueti-Ostrovsky S, Yehezkel G, Fridmann-Sirkis Y, Barak Z, Gitler D, Israelson A, Engel S. Blocking an epitope of misfolded SOD1 ameliorates disease phenotype in a model of amyotrophic lateral sclerosis. Brain 2023; 146:4594-4607. [PMID: 37394908 DOI: 10.1093/brain/awad222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 05/01/2023] [Accepted: 06/11/2023] [Indexed: 07/04/2023] Open
Abstract
The current strategies to mitigate the toxicity of misfolded superoxide dismutase 1 (SOD1) in familial amyotrophic lateral sclerosis via blocking SOD1 expression in the CNS are indiscriminative for misfolded and intact proteins, and as such, entail a risk of depriving CNS cells of their essential antioxidant potential. As an alternative approach to neutralize misfolded and spare unaffected SOD1 species, we developed scFv-SE21 antibody that blocks the β6/β7 loop epitope exposed exclusively in misfolded SOD1. The β6/β7 loop epitope has previously been proposed to initiate amyloid-like aggregation of misfolded SOD1 and mediate its prion-like activity. The adeno-associated virus-mediated expression of scFv-SE21 in the CNS of hSOD1G37R mice rescued spinal motor neurons, reduced the accumulation of misfolded SOD1, decreased gliosis and thus delayed disease onset and extended survival by 90 days. The results provide evidence for the role of the exposed β6/β7 loop epitope in the mechanism of neurotoxic gain-of-function of misfolded SOD1 and open avenues for the development of mechanism-based anti-SOD1 therapeutics, whose selective targeting of misfolded SOD1 species may entail a reduced risk of collateral oxidative damage to the CNS.
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Affiliation(s)
- Shamchal Bakavayev
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Alexandra Stavsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Shirel Argueti-Ostrovsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Galit Yehezkel
- Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Yael Fridmann-Sirkis
- Department of Life Sciences Core Facilities, Faculty of Biochemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Zeev Barak
- Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
- The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Adrian Israelson
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
- The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Stanislav Engel
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
- The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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Stoler O, Stavsky A, Khrapunsky Y, Melamed I, Stutzmann GE, Gitler D, Sekler I, Fleidervish I. Frequency- and spike-timing-dependent mitochondrial Ca 2+ signaling regulates the metabolic rate and synaptic efficacy in cortical. eLife 2022; 11:74606. [PMID: 35192454 PMCID: PMC8906805 DOI: 10.7554/elife.74606] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 02/20/2022] [Indexed: 11/13/2022] Open
Abstract
Mitochondrial activity is crucial for the plasticity of central synapses, but how the firing pattern of pre- and postsynaptic neurons affects the mitochondria remains elusive. We recorded changes in the fluorescence of cytosolic and mitochondrial Ca2+ indicators in cell bodies, axons, and dendrites of cortical pyramidal neurons in mouse brain slices while evoking pre- and postsynaptic spikes. Postsynaptic spike firing elicited fast mitochondrial Ca2+ responses that were about threefold larger in the somas and apical dendrites than in basal dendrites and axons. The amplitude of these responses and metabolic activity were extremely sensitive to the firing frequency. Furthermore, while an EPSP alone caused no detectable Ca2+ elevation in the dendritic mitochondria, the coincidence of EPSP with a backpropagating spike produced prominent, highly localized mitochondrial Ca2+ hotspots. Our results indicate that mitochondria decode the spike firing frequency and the Hebbian temporal coincidences into the Ca2+ signals, which are further translated into the metabolic output and most probably lead to long-term changes in synaptic efficacy.
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Affiliation(s)
- Ohad Stoler
- Depatrment of Physiology and Cell Biology, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Alexandra Stavsky
- Depatrment of Physiology and Cell Biology, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Yana Khrapunsky
- Depatrment of Physiology and Cell Biology, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Israel Melamed
- Depatrment of Physiology and Cell Biology, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Grace E Stutzmann
- Rosalind Franklin University of Medicine and Science, North Chicago, United States
| | - Daniel Gitler
- Depatrment of Physiology and Cell Biology, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Israel Sekler
- Depatrment of Physiology and Cell Biology, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Ilya Fleidervish
- Depatrment of Physiology and Cell Biology, Ben Gurion University of the Negev, Beer Sheva, Israel
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Stavsky A, Stoler O, Kostic M, Katoshevsky T, Assali EA, Savic I, Amitai Y, Prokisch H, Leiz S, Daumer-Haas C, Fleidervish I, Perocchi F, Gitler D, Sekler I. Author Correction: Aberrant activity of mitochondrial NCLX is linked to impaired synaptic transmission and is associated with mental retardation. Commun Biol 2021; 4:755. [PMID: 34127779 PMCID: PMC8203658 DOI: 10.1038/s42003-021-02312-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Affiliation(s)
- Alexandra Stavsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ohad Stoler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Marko Kostic
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Tomer Katoshevsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Essam A Assali
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ivana Savic
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Yael Amitai
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Holger Prokisch
- Institute of Human Genetics, School of Medicine, Technische Universität München, Munich, Germany.,Institute of Neurogenomics, Helmholtz Zentrum München, Munich, Germany
| | - Steffen Leiz
- Department of Pediatrics, Klinikum Dritter Orden, Munich, Germany
| | | | - Ilya Fleidervish
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Fabiana Perocchi
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC), Helmholtz Zentrum München, Munich, Germany.,Munich Cluster for Systems Neurology, Munich, Germany
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel. .,Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel. .,Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
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6
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Stavsky A, Stoler O, Kostic M, Katoshevsky T, Assali EA, Savic I, Amitai Y, Prokisch H, Leiz S, Daumer-Haas C, Fleidervish I, Perocchi F, Gitler D, Sekler I. Aberrant activity of mitochondrial NCLX is linked to impaired synaptic transmission and is associated with mental retardation. Commun Biol 2021; 4:666. [PMID: 34079053 PMCID: PMC8172942 DOI: 10.1038/s42003-021-02114-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 03/22/2021] [Indexed: 02/04/2023] Open
Abstract
Calcium dynamics control synaptic transmission. Calcium triggers synaptic vesicle fusion, determines release probability, modulates vesicle recycling, participates in long-term plasticity and regulates cellular metabolism. Mitochondria, the main source of cellular energy, serve as calcium signaling hubs. Mitochondrial calcium transients are primarily determined by the balance between calcium influx, mediated by the mitochondrial calcium uniporter (MCU), and calcium efflux through the sodium/lithium/calcium exchanger (NCLX). We identified a human recessive missense SLC8B1 variant that impairs NCLX activity and is associated with severe mental retardation. On this basis, we examined the effect of deleting NCLX in mice on mitochondrial and synaptic calcium homeostasis, synaptic activity, and plasticity. Neuronal mitochondria exhibited basal calcium overload, membrane depolarization, and a reduction in the amplitude and rate of calcium influx and efflux. We observed smaller cytoplasmic calcium transients in the presynaptic terminals of NCLX-KO neurons, leading to a lower probability of release and weaker transmission. In agreement, synaptic facilitation in NCLX-KO hippocampal slices was enhanced. Importantly, deletion of NCLX abolished long term potentiation of Schaffer collateral synapses. Our results show that NCLX controls presynaptic calcium transients that are crucial for defining synaptic strength as well as short- and long-term plasticity, key elements of learning and memory processes.
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Affiliation(s)
- Alexandra Stavsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ohad Stoler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Marko Kostic
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Tomer Katoshevsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Essam A Assali
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ivana Savic
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Yael Amitai
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Holger Prokisch
- Institute of Human Genetics, School of Medicine, Technische Universität München, Munich, Germany
- Institute of Neurogenomics, Helmholtz Zentrum München, Munich, Germany
| | - Steffen Leiz
- Department of Pediatrics, Klinikum Dritter Orden, Munich, Germany
| | | | - Ilya Fleidervish
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Fabiana Perocchi
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC), Helmholtz Zentrum München, Munich, Germany
- Munich Cluster for Systems Neurology, Munich, Germany
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
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Vitic Z, Safory H, Jovanovic VM, Sarusi Y, Stavsky A, Kahn J, Kuzmina A, Toker L, Gitler D, Taube R, Friedel RH, Engelender S, Brodski C. BMP5/7 protect dopaminergic neurons in an α-synuclein mouse model of Parkinson's disease. Brain 2021; 144:e15. [PMID: 33253359 PMCID: PMC7940172 DOI: 10.1093/brain/awaa368] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Affiliation(s)
- Zagorka Vitic
- Department of Physiology and Cell Biology, Zlotowski Center for Neuroscience, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105 Be'er Sheva, Israel
| | - Hazem Safory
- Department of Biochemistry, The B. Rappaport Faculty of Medicine and Institute of Medical Research, Technion-Israel Institute of Technology, Haifa 31096, Israel
| | - Vukasin M Jovanovic
- National Center for Advancing Translational Sciences (NCATS), Stem Cell Translation Laboratory (SCTL), National Institutes of Health (NIH), Rockville, MD 20850, USA
| | - Yael Sarusi
- Department of Physiology and Cell Biology, Zlotowski Center for Neuroscience, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105 Be'er Sheva, Israel
| | - Alexandra Stavsky
- Department of Physiology and Cell Biology, Zlotowski Center for Neuroscience, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105 Be'er Sheva, Israel
| | - Joy Kahn
- Department of Physiology and Cell Biology, Zlotowski Center for Neuroscience, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105 Be'er Sheva, Israel
| | - Alona Kuzmina
- Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105 Be'er Sheva, Israel
| | - Lilah Toker
- Neuro-SysMed Center of Excellence for Clinical Research in Neurological Diseases, Department of Neurology, Haukeland University Hospital, 5021 Bergen, Norway
- Department of Clinical Medicine, University of Bergen, 5007 Bergen, Norway
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Zlotowski Center for Neuroscience, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105 Be'er Sheva, Israel
| | - Ran Taube
- Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105 Be'er Sheva, Israel
| | - Roland H Friedel
- Departments of Neuroscience and Neurosurgery, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Simone Engelender
- Department of Biochemistry, The B. Rappaport Faculty of Medicine and Institute of Medical Research, Technion-Israel Institute of Technology, Haifa 31096, Israel
| | - Claude Brodski
- Department of Physiology and Cell Biology, Zlotowski Center for Neuroscience, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105 Be'er Sheva, Israel
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Aghanoori MR, Margulets V, Smith DR, Kirshenbaum LA, Gitler D, Fernyhough P. Sensory neurons derived from diabetic rats exhibit deficits in functional glycolysis and ATP that are ameliorated by IGF-1. Mol Metab 2021; 49:101191. [PMID: 33592336 PMCID: PMC7940986 DOI: 10.1016/j.molmet.2021.101191] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 02/04/2021] [Accepted: 02/09/2021] [Indexed: 11/29/2022] Open
Abstract
Objective The distal dying-back of the longest nerve fibres is a hallmark of diabetic neuropathy, and impaired provision of energy in the form of adenosine triphosphate (ATP) may contribute to this neurodegenerative process. We hypothesised that energy supplementation via glycolysis and/or mitochondrial oxidative phosphorylation is compromised in cultured dorsal root ganglion (DRG) sensory neurons from diabetic rodents, thus contributing to axonal degeneration. Functional analysis of glycolysis and mitochondrial respiration and real-time measurement of ATP levels in live cells were our specific means to test this hypothesis. Methods DRG neuron cultures from age-matched control or streptozotocin (STZ)-induced type 1 diabetic rats were used for in vitro studies. Three plasmids containing ATP biosensors of varying affinities were transfected into neurons to study endogenous ATP levels in real time. The Seahorse XF analyser was used for glycolysis and mitochondrial respiration measurements. Results Fluorescence resonance energy transfer (FRET) efficiency (YFP/CFP ratio) of the ATP biosensors AT1.03 (low affinity) and AT1.03YEMK (medium affinity) were significantly higher than that measured using the ATP-insensitive construct AT1.03R122/6K in both cell bodies and neurites of DRG neurons (p < 0.0001). The ATP level was homogenous along the axons but higher in cell bodies in cultured DRG neurons from both control and diabetic rats. Treatment with oligomycin (an ATP synthase inhibitor in mitochondria) decreased the ATP levels in cultured DRG neurons. Likewise, blockade of glycolysis using 2-deoxy-d-glucose (2-DG: a glucose analogue) reduced ATP levels (p < 0.001). Cultured DRG neurons derived from diabetic rats showed a diminishment of ATP levels (p < 0.01), glycolytic capacity, glycolytic reserve and non-glycolytic acidification. Application of insulin-like growth factor-1 (IGF-1) significantly elevated all the above parameters in DRG neurons from diabetic rats. Oligomycin pre-treatment of DRG neurons, to block oxidative phosphorylation, depleted the glycolytic reserve and lowered basal respiration in sensory neurons derived from control and diabetic rats. Depletion was much higher in sensory neurons from diabetic rats compared to control rats. In addition, an acute increase in glucose concentration, in the presence or absence of oligomycin, elevated parameters of glycolysis by 1.5- to 2-fold while having no impact on mitochondrial respiration. Conclusion We provide the first functional evidence for decreased glycolytic capacity in DRG neurons derived from type 1 diabetic rats. IGF-1 protected against the loss of ATP supplies in DRG cell bodies and axons in neurons derived from diabetic rats by augmenting various parameters of glycolysis and mitochondrial respiration. There is an energy deficit in the form of ATP in cell bodies and axons of sensory neurons derived from diabetic rats. Glycolytic capacity and reserve are depleted in sensory neurons from diabetic rats. IGF-1 treatment reverses the energy deficit and glycolysis defect in sensory neurons from diabetic rats. Glycolysis is a significant source of energy comprising up to 30% of ATP in adult rat sensory neurons.
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Affiliation(s)
- Mohamad-Reza Aghanoori
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada; Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada
| | - Vicky Margulets
- Department of Physiology & Pathophysiology, University of Manitoba, Winnipeg, MB, Canada
| | - Darrell R Smith
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
| | - Lorrie A Kirshenbaum
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada; Department of Physiology & Pathophysiology, University of Manitoba, Winnipeg, MB, Canada; Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Paul Fernyhough
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada; Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada.
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Schechter M, Atias M, Abd Elhadi S, Davidi D, Gitler D, Sharon R. α-Synuclein facilitates endocytosis by elevating the steady-state levels of phosphatidylinositol 4,5-bisphosphate. J Biol Chem 2020; 295:18076-18090. [PMID: 33087443 PMCID: PMC7939461 DOI: 10.1074/jbc.ra120.015319] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/08/2020] [Indexed: 12/12/2022] Open
Abstract
α-Synuclein (α-Syn) is a protein implicated in the pathogenesis of Parkinson's disease (PD). It is an intrinsically disordered protein that binds acidic phospholipids. Growing evidence supports a role for α-Syn in membrane trafficking, including, mechanisms of endocytosis and exocytosis, although the exact role of α-Syn in these mechanisms is currently unclear. Here we investigate the associations of α-Syn with the acidic phosphoinositides (PIPs), phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and phosphatidylinositol 3,4-bisphosphate (PI(3,4)P2). Our results show that α-Syn colocalizes with PIP2 and the phosphorylated active form of the clathrin adaptor protein 2 (AP2) at clathrin-coated pits. Using endocytosis of transferrin as an indicator for clathrin-mediated endocytosis (CME), we find that α-Syn involvement in endocytosis is specifically mediated through PI(4,5)P2 levels on the plasma membrane. In accord with their effects on PI(4,5)P2 levels, the PD associated A30P, E46K, and A53T mutations in α-Syn further enhance CME in neuronal and nonneuronal cells. However, lysine to glutamic acid substitutions at the KTKEGV repeat domain of α-Syn, which interfere with phospholipid binding, are ineffective in enhancing CME. We further show that the rate of synaptic vesicle (SV) endocytosis is differentially affected by the α-Syn mutations and associates with their effects on PI(4,5)P2 levels, however, with the exception of the A30P mutation. This study provides evidence for a critical involvement of PIPs in α-Syn-mediated membrane trafficking.
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Affiliation(s)
- Meir Schechter
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Merav Atias
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Suaad Abd Elhadi
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Dana Davidi
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ronit Sharon
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
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10
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Mertens R, Melchert S, Gitler D, Schou MB, Saether SG, Vaaler A, Piepgras J, Kochova E, Benfenati F, Ahnert-Hilger G, Ruprecht K, Höltje M. Epitope specificity of anti-synapsin autoantibodies: Differential targeting of synapsin I domains. PLoS One 2018; 13:e0208636. [PMID: 30543686 PMCID: PMC6292584 DOI: 10.1371/journal.pone.0208636] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 11/20/2018] [Indexed: 01/07/2023] Open
Abstract
OBJECTIVE To identify the specific domains of the presynaptic protein synapsin targeted by recently described autoantibodies to synapsin. METHODS Sera of 20 and CSF of two patients with different psychiatric and neurological disorders previously tested positive for immunoglobulin (Ig)G antibodies to full-length synapsin were screened for IgG against synapsin I domains using HEK293 cells transfected with constructs encoding different domains of rat synapsin Ia. Additionally, IgG subclasses were determined using full-length synapsin Ia. Serum and CSF from one patient were also screened for IgA autoantibodies to synapsin I domains. Sera from nine and CSF from two healthy subjects were analyzed as controls. RESULTS IgG in serum from 12 of 20 IgG synapsin full-length positive patients, but from none of the healthy controls, bound to synapsin domains. Of these 12 sera, six bound to the A domain, five to the D domain, and one to the B- (and possibly A-), D-, and E-domains of synapsin I. IgG antibodies to the D-domain were also detected in one of the CSF samples. Determination of IgG subclasses detected IgG1 in two sera and one CSF, IgG2 in none of the samples, IgG3 in two sera, and IgG4 in eight sera. One patient known to be positive for IgA antibodies to full-length synapsin had IgA antibodies to the D-domain in serum and CSF. CONCLUSIONS Anti-synapsin autoantibodies preferentially bind to either the A- or the D-domain of synapsin I.
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Affiliation(s)
- Robert Mertens
- Institute of Integrative Neuroanatomy, Charité –Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Sarah Melchert
- Institute of Integrative Neuroanatomy, Charité –Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Morten Brix Schou
- Department of Psychiatry, St. Olav’s University Hospital, Trondheim, Norway
- Department of Mental Health, Norwegian University of Science and Technology, Trondheim, Norway
| | - Sverre Georg Saether
- Department of Psychiatry, St. Olav’s University Hospital, Trondheim, Norway
- Department of Mental Health, Norwegian University of Science and Technology, Trondheim, Norway
| | - Arne Vaaler
- Department of Psychiatry, St. Olav’s University Hospital, Trondheim, Norway
- Department of Mental Health, Norwegian University of Science and Technology, Trondheim, Norway
| | - Johannes Piepgras
- Institute of Integrative Neuroanatomy, Charité –Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Elena Kochova
- Institute of Integrative Neuroanatomy, Charité –Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy
| | - Gudrun Ahnert-Hilger
- Institute of Integrative Neuroanatomy, Charité –Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Klemens Ruprecht
- Department of Neurology, Charité –Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Markus Höltje
- Institute of Integrative Neuroanatomy, Charité –Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
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11
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Shusterman E, Beharier O, Levy S, Zarivach R, Etzion Y, Campbell CR, Lee IH, Dinudom A, Cook DI, Peretz A, Katz A, Gitler D, Moran A. Zinc transport and the inhibition of the L-type calcium channel are two separable functions of ZnT-1. Metallomics 2017; 9:228-238. [PMID: 28091657 DOI: 10.1039/c6mt00296j] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Traditionally, proteins are considered to perform a single role, be it as an enzyme, a channel, a transporter or as a structural scaffold. However, recent studies have described moonlighting proteins that perform distinct and independent functions; for example, TRPM7 is both an ion channel and a kinase. ZnT-1 is a member of the Carrier Diffusion Facilitator family that is expressed throughout the phylogenetic tree from bacteria to humans. Since its cloning in 1995, ZnT-1 is considered a major extruder of Zn2+ based on its capability to protect cells against zinc toxicity. Recently, we reported that ZnT-1 inhibits the L-type calcium channel (LTCC), a major Zn2+ and Ca2+ entry pathway. Here we show that ZnT-1 is a dual-function protein by demonstrating that its abilities to exchange Zn2+/H+ and to inhibit the LTCC are independent of each other and are mediated by different parts of the protein. Specifically, mutations in the membrane-spanning helices that render ZnT-1 unable to transport zinc do not prevent it from inhibiting the LTCC. Moreover, a fragment consisting of the intracellular ZnT-1 C-terminal, which lacks all ion-transfer segments, inhibits the LTCC as efficiently as wild-type ZnT-1. Our data therefore indicates that ZnT-1 performs two structurally independent functions related to zinc homeostasis.
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Affiliation(s)
- Eden Shusterman
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel.
| | - Ofer Beharier
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel.
| | - Shiri Levy
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel.
| | - Raz Zarivach
- Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Yoram Etzion
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel.
| | - Craig R Campbell
- Discipline of Physiology, The Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, NSW 2006, Australia
| | - Il-Ha Lee
- Discipline of Physiology, The Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, NSW 2006, Australia
| | - Anuwat Dinudom
- Discipline of Physiology, The Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, NSW 2006, Australia
| | - David I Cook
- Discipline of Physiology, The Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, NSW 2006, Australia
| | - Asher Peretz
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Amos Katz
- Department of Cardiology, Barzilai University Medical Center, Ashkelon, Israel and Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel. and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Arie Moran
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel. and Discipline of Physiology, The Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, NSW 2006, Australia and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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12
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Höltje M, Mertens R, Schou MB, Saether SG, Kochova E, Jarius S, Prüss H, Komorowski L, Probst C, Paul F, Bellmann-Strobl J, Gitler D, Benfenati F, Piepgras J, Ahnert-Hilger G, Ruprecht K. Synapsin-antibodies in psychiatric and neurological disorders: Prevalence and clinical findings. Brain Behav Immun 2017; 66:125-134. [PMID: 28733081 DOI: 10.1016/j.bbi.2017.07.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Revised: 07/01/2017] [Accepted: 07/17/2017] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE To study the prevalence of autoantibodies to synapsin in patients with psychiatric and neurological disorders and to describe clinical findings in synapsin antibody positive patients. METHODS Sera of 375 patients with different psychiatric and neurological disorders and sera of 97 healthy controls were screened (dilution 1:320) for anti-synapsin IgG using HEK293 cells transfected with rat synapsin Ia. Positive sera were further analyzed by immunoblots with brain tissue from wild type and synapsin knock out mice and with HEK293 cells transfected with human synapsin Ia and Ib. Binding of synapsin IgG positive sera to primary neurons was studied using murine hippocampal neurons. RESULTS IgG in serum from 23 (6.1%) of 375 patients, but from none of the 97 healthy controls (p=0.007), bound to rat synapsin Ia transfected cells with a median (range) titer of 1:1000 (1:320-1:100,000). Twelve of the 23 positive sera reacted with a protein of the molecular size of synapsin I in immunoblots of wild type but not of synapsin knock out mouse brain tissue. Out of 19/23 positive sera available for testing, 13 bound to human synapsin Ia and 16 to human synapsin Ib transfected cells. Synapsin IgG positive sera stained fixed and permeabilized murine hippocampal neurons. Synapsin IgG positive patients had various psychiatric and neurological disorders. Tumors were documented in 2 patients (melanoma, small cell lung carcinoma); concomitant anti-neuronal or other autoantibodies were present in 8 patients. CONCLUSIONS Autoantibodies to human synapsin Ia and Ib are detectable in a proportion of sera from patients with different psychiatric and neurological disorders, warranting further investigation into the potential pathophysiological relevance of these antibodies.
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Affiliation(s)
- Markus Höltje
- Institute of Integrative Neuroanatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany.
| | - Robert Mertens
- Institute of Integrative Neuroanatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany.
| | - Morten Brix Schou
- St. Olav's Hospital, Trondheim University Hospital, Department of Psychiatry, Trondheim, Norway; Norwegian University of Science and Technology, Faculty of Medicine and Health Science, Department of Mental Health, Trondheim, Norway.
| | - Sverre Georg Saether
- St. Olav's Hospital, Trondheim University Hospital, Department of Psychiatry, Trondheim, Norway; Norwegian University of Science and Technology, Faculty of Medicine and Health Science, Department of Mental Health, Trondheim, Norway.
| | - Elena Kochova
- Institute of Integrative Neuroanatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany.
| | - Sven Jarius
- Molecular Neuroimmunology Group, Department of Neurology, University of Heidelberg, Germany.
| | - Harald Prüss
- Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany; German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin, Germany.
| | - Lars Komorowski
- Institute for Experimental Immunology, Affiliated to Euroimmun AG, Lübeck, Germany.
| | - Christian Probst
- Institute for Experimental Immunology, Affiliated to Euroimmun AG, Lübeck, Germany.
| | - Friedemann Paul
- Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany; NeuroCure Clinical Research Center, Charité - Universitätsmedizin Berlin, Berlin, Germany; Experimental and Clinical Research Center, Max Delbrueck Center for Molecular Medicine and Charité - Universitätsmedizin Berlin, Germany.
| | - Judith Bellmann-Strobl
- NeuroCure Clinical Research Center, Charité - Universitätsmedizin Berlin, Berlin, Germany; Experimental and Clinical Research Center, Max Delbrueck Center for Molecular Medicine and Charité - Universitätsmedizin Berlin, Germany.
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.
| | - Johannes Piepgras
- Institute of Integrative Neuroanatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany; Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
| | - Gudrun Ahnert-Hilger
- Institute of Integrative Neuroanatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany.
| | - Klemens Ruprecht
- Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
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13
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Ganguly A, Han X, Das U, Wang L, Loi J, Sun J, Gitler D, Caillol G, Leterrier C, Yates JR, Roy S. Hsc70 chaperone activity is required for the cytosolic slow axonal transport of synapsin. J Cell Biol 2017; 216:2059-2074. [PMID: 28559423 PMCID: PMC5496608 DOI: 10.1083/jcb.201604028] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 08/22/2016] [Accepted: 04/17/2017] [Indexed: 12/19/2022] Open
Abstract
Using proteomics, live microscopy, and superresolution microscopy, Ganguly et al. offer insight into the molecular composition of cytosolic cargo complexes conveyed in slow axonal transport, identifying the heat shock protein Hsc70 as a major regulator of this transport. Soluble cytosolic proteins vital to axonal and presynaptic function are synthesized in the neuronal soma and conveyed via slow axonal transport. Our previous studies suggest that the overall slow transport of synapsin is mediated by dynamic assembly/disassembly of cargo complexes followed by short-range vectorial transit (the “dynamic recruitment” model). However, neither the composition of these complexes nor the mechanistic basis for the dynamic behavior is understood. In this study, we first examined putative cargo complexes associated with synapsin using coimmunoprecipitation and multidimensional protein identification technology mass spectrometry (MS). MS data indicate that synapsin is part of a multiprotein complex enriched in chaperones/cochaperones including Hsc70. Axonal synapsin–Hsc70 coclusters are also visualized by two-color superresolution microscopy. Inhibition of Hsc70 ATPase activity blocked the slow transport of synapsin, disrupted axonal synapsin organization, and attenuated Hsc70–synapsin associations, advocating a model where Hsc70 activity dynamically clusters cytosolic proteins into cargo complexes, allowing transport. Collectively, our study offers insight into the molecular organization of cytosolic transport complexes and identifies a novel regulator of slow transport.
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Affiliation(s)
- Archan Ganguly
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Xuemei Han
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA
| | - Utpal Das
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Lina Wang
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI
| | - Jonathan Loi
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI
| | - Jichao Sun
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev and Zlotowski Center for Neuroscience, Beer-Sheva, Israel
| | - Ghislaine Caillol
- Aix Marseille Université, Centre National de la Recherche Scientifique, NICN UMR7259, Marseille, France
| | - Christophe Leterrier
- Aix Marseille Université, Centre National de la Recherche Scientifique, NICN UMR7259, Marseille, France
| | - John R Yates
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA
| | - Subhojit Roy
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI .,Department of Neuroscience, University of Wisconsin-Madison, Madison, WI
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14
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Eitan E, Braverman C, Tichon A, Gitler D, Hutchison ER, Mattson MP, Priel E. Excitotoxic and Radiation Stress Increase TERT Levels in the Mitochondria and Cytosol of Cerebellar Purkinje Neurons. Cerebellum 2017; 15:509-17. [PMID: 26374457 DOI: 10.1007/s12311-015-0720-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Telomerase reverse transcriptase (TERT) is the catalytic subunit of telomerase, an enzyme that elongates telomeres at the ends of chromosomes during DNA replication. Recently, it was shown that TERT has additional roles in cell survival, mitochondrial function, DNA repair, and Wnt signaling, all of which are unrelated to telomeres. Here, we demonstrate that TERT is enriched in Purkinje neurons, but not in the granule cells of the adult mouse cerebellum. TERT immunoreactivity in Purkinje neurons is present in the nucleus, mitochondria, and cytoplasm. Furthermore, TERT co-localizes with mitochondrial markers, and immunoblot analysis of protein extracts from isolated mitochondria and synaptosomes confirmed TERT localization in mitochondria. TERT expression in Purkinje neurons increased significantly in response to two stressors: a sub-lethal dose of X-ray radiation and exposure to a high glutamate concentration. While X-ray radiation increased TERT levels in the nucleus, glutamate exposure elevated TERT levels in mitochondria. Our findings suggest that in mature Purkinje neurons, TERT is present both in the nucleus and in mitochondria, where it may participate in adaptive responses of the neurons to excitotoxic and radiation stress.
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Affiliation(s)
- Erez Eitan
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel. .,Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD, 21224, USA.
| | - Carmel Braverman
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel
| | - Ailone Tichon
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel
| | - Emmette R Hutchison
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD, 21224, USA
| | - Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD, 21224, USA
| | - Esther Priel
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel
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15
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Piepgras J, Höltje M, Otto C, Harms H, Satapathy A, Cesca F, Benfenati F, Gitler D, Pich A, Zander JF, Ahnert-Hilger G, Ruprecht K. Intrathecal immunoglobulin A and G antibodies to synapsin in a patient with limbic encephalitis. Neurol Neuroimmunol Neuroinflamm 2015; 2:e169. [PMID: 26587554 PMCID: PMC4635552 DOI: 10.1212/nxi.0000000000000169] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 08/25/2015] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To report on the identification of intrathecally synthesized immunoglobulin A (IgA) and immunoglobulin G (IgG) antibodies to synapsin, a synaptic vesicle-associated protein, in a patient with limbic encephalitis. METHODS Methods included clinical characterization, indirect immunofluorescence, immunoprecipitation, mass spectrometry, immunoblots of wild-type and synapsin I/II/III knockout mice, and cell-based assays with synapsin Ia, Ib, IIa, and IIb plasmids. RESULTS A 69-year-old man presented with confusion, disorientation, seizures, and left hippocampal hyperintensities on MRI. CSF examinations revealed an intrathecal IgA and IgG synthesis. Except for IgG antibodies to voltage-gated potassium channels in CSF, screening for known neuronal autoantibodies in serum and CSF was negative. However, indirect immunofluorescence using the patient's CSF showed binding of IgA to mouse hippocampus, amygdala, and cerebellum. Immunoprecipitation with CSF IgA followed by mass spectrometry identified synapsin as autoantigenic target. Knockout tissues and cell-based assays confirmed that IgA and IgG in the patient's CSF and serum reacted with synapsin Ia, Ib, and IIa. Calculation of antibody indices proved intrathecal synthesis of anti-synapsin IgA and IgG. The patient responded clinically to immunotherapy but developed left hippocampal atrophy. CSF IgA or IgG of the patient did not bind to live, unfixed, and nonpermeabilized mouse hippocampal neurons, compatible with synapsin being an intracellular antigen. CONCLUSIONS This report identifies isoforms of the synaptic vesicle-associated protein synapsin as targets of intrathecally produced IgA and IgG antibodies in a patient with limbic encephalitis. Future studies should clarify the prevalence and pathogenic relevance of anti-synapsin antibodies in limbic encephalitis.
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Affiliation(s)
- Johannes Piepgras
- Department of Neurology (J.P., K.R.) and Institute for Integrative Neuroanatomy (M.H., J.-F.Z., G.A.-H.), Charité-Universitätsmedizin Berlin; St. Josefs-Krankenhaus Potsdam (C.O., H.H.), Germany; the Department of Neuroscience and Brain Technologies (A.S., F.C., F.B.), Istituto Italiano di Tecnologia, Genova, Italy; the Department of Physiology and Cell Biology (D.G.), Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel; and the Institute of Toxicology (A.P.), Hannover Medical School, Germany
| | - Markus Höltje
- Department of Neurology (J.P., K.R.) and Institute for Integrative Neuroanatomy (M.H., J.-F.Z., G.A.-H.), Charité-Universitätsmedizin Berlin; St. Josefs-Krankenhaus Potsdam (C.O., H.H.), Germany; the Department of Neuroscience and Brain Technologies (A.S., F.C., F.B.), Istituto Italiano di Tecnologia, Genova, Italy; the Department of Physiology and Cell Biology (D.G.), Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel; and the Institute of Toxicology (A.P.), Hannover Medical School, Germany
| | - Carolin Otto
- Department of Neurology (J.P., K.R.) and Institute for Integrative Neuroanatomy (M.H., J.-F.Z., G.A.-H.), Charité-Universitätsmedizin Berlin; St. Josefs-Krankenhaus Potsdam (C.O., H.H.), Germany; the Department of Neuroscience and Brain Technologies (A.S., F.C., F.B.), Istituto Italiano di Tecnologia, Genova, Italy; the Department of Physiology and Cell Biology (D.G.), Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel; and the Institute of Toxicology (A.P.), Hannover Medical School, Germany
| | - Hendrik Harms
- Department of Neurology (J.P., K.R.) and Institute for Integrative Neuroanatomy (M.H., J.-F.Z., G.A.-H.), Charité-Universitätsmedizin Berlin; St. Josefs-Krankenhaus Potsdam (C.O., H.H.), Germany; the Department of Neuroscience and Brain Technologies (A.S., F.C., F.B.), Istituto Italiano di Tecnologia, Genova, Italy; the Department of Physiology and Cell Biology (D.G.), Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel; and the Institute of Toxicology (A.P.), Hannover Medical School, Germany
| | - Annyesha Satapathy
- Department of Neurology (J.P., K.R.) and Institute for Integrative Neuroanatomy (M.H., J.-F.Z., G.A.-H.), Charité-Universitätsmedizin Berlin; St. Josefs-Krankenhaus Potsdam (C.O., H.H.), Germany; the Department of Neuroscience and Brain Technologies (A.S., F.C., F.B.), Istituto Italiano di Tecnologia, Genova, Italy; the Department of Physiology and Cell Biology (D.G.), Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel; and the Institute of Toxicology (A.P.), Hannover Medical School, Germany
| | - Fabrizia Cesca
- Department of Neurology (J.P., K.R.) and Institute for Integrative Neuroanatomy (M.H., J.-F.Z., G.A.-H.), Charité-Universitätsmedizin Berlin; St. Josefs-Krankenhaus Potsdam (C.O., H.H.), Germany; the Department of Neuroscience and Brain Technologies (A.S., F.C., F.B.), Istituto Italiano di Tecnologia, Genova, Italy; the Department of Physiology and Cell Biology (D.G.), Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel; and the Institute of Toxicology (A.P.), Hannover Medical School, Germany
| | - Fabio Benfenati
- Department of Neurology (J.P., K.R.) and Institute for Integrative Neuroanatomy (M.H., J.-F.Z., G.A.-H.), Charité-Universitätsmedizin Berlin; St. Josefs-Krankenhaus Potsdam (C.O., H.H.), Germany; the Department of Neuroscience and Brain Technologies (A.S., F.C., F.B.), Istituto Italiano di Tecnologia, Genova, Italy; the Department of Physiology and Cell Biology (D.G.), Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel; and the Institute of Toxicology (A.P.), Hannover Medical School, Germany
| | - Daniel Gitler
- Department of Neurology (J.P., K.R.) and Institute for Integrative Neuroanatomy (M.H., J.-F.Z., G.A.-H.), Charité-Universitätsmedizin Berlin; St. Josefs-Krankenhaus Potsdam (C.O., H.H.), Germany; the Department of Neuroscience and Brain Technologies (A.S., F.C., F.B.), Istituto Italiano di Tecnologia, Genova, Italy; the Department of Physiology and Cell Biology (D.G.), Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel; and the Institute of Toxicology (A.P.), Hannover Medical School, Germany
| | - Andreas Pich
- Department of Neurology (J.P., K.R.) and Institute for Integrative Neuroanatomy (M.H., J.-F.Z., G.A.-H.), Charité-Universitätsmedizin Berlin; St. Josefs-Krankenhaus Potsdam (C.O., H.H.), Germany; the Department of Neuroscience and Brain Technologies (A.S., F.C., F.B.), Istituto Italiano di Tecnologia, Genova, Italy; the Department of Physiology and Cell Biology (D.G.), Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel; and the Institute of Toxicology (A.P.), Hannover Medical School, Germany
| | - Johannes-Friedrich Zander
- Department of Neurology (J.P., K.R.) and Institute for Integrative Neuroanatomy (M.H., J.-F.Z., G.A.-H.), Charité-Universitätsmedizin Berlin; St. Josefs-Krankenhaus Potsdam (C.O., H.H.), Germany; the Department of Neuroscience and Brain Technologies (A.S., F.C., F.B.), Istituto Italiano di Tecnologia, Genova, Italy; the Department of Physiology and Cell Biology (D.G.), Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel; and the Institute of Toxicology (A.P.), Hannover Medical School, Germany
| | - Gudrun Ahnert-Hilger
- Department of Neurology (J.P., K.R.) and Institute for Integrative Neuroanatomy (M.H., J.-F.Z., G.A.-H.), Charité-Universitätsmedizin Berlin; St. Josefs-Krankenhaus Potsdam (C.O., H.H.), Germany; the Department of Neuroscience and Brain Technologies (A.S., F.C., F.B.), Istituto Italiano di Tecnologia, Genova, Italy; the Department of Physiology and Cell Biology (D.G.), Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel; and the Institute of Toxicology (A.P.), Hannover Medical School, Germany
| | - Klemens Ruprecht
- Department of Neurology (J.P., K.R.) and Institute for Integrative Neuroanatomy (M.H., J.-F.Z., G.A.-H.), Charité-Universitätsmedizin Berlin; St. Josefs-Krankenhaus Potsdam (C.O., H.H.), Germany; the Department of Neuroscience and Brain Technologies (A.S., F.C., F.B.), Istituto Italiano di Tecnologia, Genova, Italy; the Department of Physiology and Cell Biology (D.G.), Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel; and the Institute of Toxicology (A.P.), Hannover Medical School, Germany
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Beharier O, Shusterman E, Szaingurten-Solodkin I, Weintraub AY, Sheiner E, Swissa SS, Gitler D, Hershkovitz R. Placental growth factor concentration in maternal circulation decreases after fetal death: lessons from a case series study. Arch Gynecol Obstet 2015; 292:1027-32. [PMID: 25940355 DOI: 10.1007/s00404-015-3729-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 04/20/2015] [Indexed: 01/23/2023]
Abstract
PURPOSE Placental growth factor (PlGF) has been suggested as a possible biomarker for major placenta-related disorders such as preeclampsia and intrauterine growth restriction. However, experimental findings suggest that PlGF concentrations may be influenced by other factors besides the placenta. In the present study, we examined how acute fetal injury affects PlGF concentrations in maternal circulation. We therefore monitored PlGF concentrations in maternal circulation before and after feticide. METHODS A prospective comparative study was performed. Blood samples were drawn prospectively between January and July 2012, before and after feticide at predetermined time points in relation to the procedure (0, 30, 60, and 120 min). The levels of lactate dehydrogenase (LDH) in the maternal circulation were measured to detect acute tissue damage. PlGF concentrations were measured by standard human ELISA. RESULTS Following feticide (60 and 120 min), PlGF concentrations decreased significantly compared to the concentrations before feticide. LDH concentrations did not change before and after feticide. CONCLUSIONS Our finding, along with the detailed review of the literature described in our work, supports a new concept in which primary fetal distress can affect PlGF concentration in maternal circulation. A large-scale study is required to strengthen our finding.
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Affiliation(s)
- Ofer Beharier
- Department of Obstetrics and Gynecology, Soroka University Medical Center and Ben-Gurion University of the Negev, Beer-Sheva, Israel.
| | - Eden Shusterman
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Irit Szaingurten-Solodkin
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Adi Y Weintraub
- Department of Obstetrics and Gynecology, Soroka University Medical Center and Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Eyal Sheiner
- Department of Obstetrics and Gynecology, Soroka University Medical Center and Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Shani S Swissa
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Reli Hershkovitz
- Department of Obstetrics and Gynecology, Soroka University Medical Center and Ben-Gurion University of the Negev, Beer-Sheva, Israel
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17
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Vasileva M, Renden R, Horstmann H, Gitler D, Kuner T. Overexpression of synapsin Ia in the rat calyx of Held accelerates short-term plasticity and decreases synaptic vesicle volume and active zone area. Front Cell Neurosci 2013; 7:270. [PMID: 24391547 PMCID: PMC3868894 DOI: 10.3389/fncel.2013.00270] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 12/04/2013] [Indexed: 01/10/2023] Open
Abstract
Synapsins are synaptic vesicle (SV) proteins organizing a component of the reserve pool of vesicles at most central nervous system synapses. Alternative splicing of the three mammalian genes results in multiple isoforms that may differentially contribute to the organization and maintenance of the SV pools. To address this, we first characterized the expression pattern of synapsin isoforms in the rat calyx of Held. At postnatal day 16, synapsins Ia, Ib, IIb and IIIa were present, while IIa-known to sustain repetitive transmission in glutamatergic terminals-was not detectable. To test if the synapsin I isoforms could mediate IIa-like effect, and if this depends on the presence of the E-domain, we overexpressed either synapsin Ia or synapsin Ib in the rat calyx of Held via recombinant adeno-associated virus-mediated gene transfer. Although the size and overall structure of the perturbed calyces remained unchanged, short-term depression and recovery from depression were accelerated upon overexpression of synapsin I isoforms. Using electron microscopic three-dimensional reconstructions we found a redistribution of SV clusters proximal to the active zones (AZ) alongside with a decrease of both AZ area and SV volume. The number of SVs at individual AZs was strongly reduced. Hence, our data indicate that the amount of synapsin Ia expressed in the calyx regulates the rate and extent of short-term synaptic plasticity by affecting vesicle recruitment to the AZ. Finally, our study reveals a novel contribution of synapsin Ia to define the surface area of AZs.
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Affiliation(s)
- Mariya Vasileva
- Institute of Anatomy and Cell Biology, Heidelberg University Heidelberg, Germany
| | - Robert Renden
- Institute of Anatomy and Cell Biology, Heidelberg University Heidelberg, Germany
| | - Heinz Horstmann
- Institute of Anatomy and Cell Biology, Heidelberg University Heidelberg, Germany
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev Beer-Sheva, Israel
| | - Thomas Kuner
- Institute of Anatomy and Cell Biology, Heidelberg University Heidelberg, Germany
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18
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Staras K, Mikulincer D, Gitler D. Monitoring and quantifying dynamic physiological processes in live neurons using fluorescence recovery after photobleaching. J Neurochem 2013; 126:213-22. [PMID: 23496032 DOI: 10.1111/jnc.12240] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 03/12/2013] [Accepted: 03/13/2013] [Indexed: 12/27/2022]
Abstract
The direct visualization of subcellular dynamic processes is often hampered by limitations in the resolving power achievable with conventional microscopy techniques. Fluorescence recovery after photobleaching has emerged as a highly informative approach to address this challenge, permitting the quantitative measurement of the movement of small organelles and proteins in living functioning cells, and offering detailed insights into fundamental cellular phenomena of physiological importance. In recent years, its implementation has benefited from the increasing availability of confocal microscopy systems and of powerful labeling techniques based on genetically encoded fluorescent proteins or other chemical markers. In this review, we present fluorescence recovery after photobleaching and related techniques in the context of contemporary neurobiological research and discuss quantitative and semi-quantitative approaches to their interpretation.
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Affiliation(s)
- Kevin Staras
- School of Life Sciences, University of Sussex, Brighton, UK
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19
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Ketzef M, Gitler D. Epileptic synapsin triple knockout mice exhibit progressive long-term aberrant plasticity in the entorhinal cortex. ACTA ACUST UNITED AC 2012; 24:996-1008. [PMID: 23236212 DOI: 10.1093/cercor/bhs384] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Studying epileptogenesis in a genetic model can facilitate the identification of factors that promote the conversion of a normal brain into one chronically prone to seizures. Synapsin triple-knockout (TKO) mice exhibit adult-onset epilepsy, thus allowing the characterization of events as preceding or following seizure onset. Although it has been proposed that a congenital reduction in inhibitory transmission is the underlying cause for epilepsy in these mice, young TKO mice are asymptomatic. We report that the genetic lesion exerts long-term progressive effects that extend well into adulthood. Although inhibitory transmission is initially reduced, it is subsequently strengthened relative to its magnitude in control mice, so that the excitation to inhibition balance in adult TKOs is inverted in favor of inhibition. In parallel, we observed long-term alterations in synaptic depression kinetics of excitatory transmission and in the extent of tonic inhibition, illustrating adaptations in synaptic properties. Moreover, age-dependent acceleration of the action potential did not occur in TKO cortical pyramidal neurons, suggesting wide-ranging secondary changes in brain excitability. In conclusion, although congenital impairments in inhibitory transmission may initiate epileptogenesis in the synapsin TKO mice, we suggest that secondary adaptations are crucial for the establishment of this epileptic network.
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Affiliation(s)
- Maya Ketzef
- Department of Physiology and Cell Biology, Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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20
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Vasileva M, Horstmann H, Geumann C, Gitler D, Kuner T. Synapsin-dependent reserveo pool of synaptic vesicles supports replenishment of the readily releasable pool under intense synaptic transmission. Eur J Neurosci 2012; 36:3005-20. [DOI: 10.1111/j.1460-9568.2012.08225.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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21
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Eitan E, Tichon A, Gitler D, Priel E. Increasing telomerase in mouse brain by novel compound protects neurons from various insults. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.lb235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Erez Eitan
- Immunology & MicrobiologyBen Gurion UniversityBehr shevaIsrael
| | - Ailon Tichon
- Immunology & MicrobiologyBen Gurion UniversityBehr shevaIsrael
| | - Daniel Gitler
- Physiology and NeurobiologyBen Gurion UniversityBehr shevaIsrael
| | - Esther Priel
- Immunology & MicrobiologyBen Gurion UniversityBehr shevaIsrael
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22
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Eitan E, Tichon A, Gazit A, Gitler D, Slavin S, Priel E. Novel telomerase-increasing compound in mouse brain delays the onset of amyotrophic lateral sclerosis. EMBO Mol Med 2012; 4:313-29. [PMID: 22351600 PMCID: PMC3376858 DOI: 10.1002/emmm.201200212] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Revised: 12/22/2011] [Accepted: 01/03/2012] [Indexed: 01/12/2023] Open
Abstract
Telomerase is expressed in the neonatal brain, in distinct regions of adult brain, and was shown to protect developing neurons from apoptosis. Telomerase reactivation by gene manipulation reverses neurodegeneration in aged telomerase-deficient mice. Hence, we and others hypothesized that increasing telomerase expression by pharmaceutical compounds may protect brain cells from death caused by damaging agents. In this study, we demonstrate for the first time that the novel compound AGS-499 increases telomerase activity and expression in the mouse brain and spinal cord (SC). It exerts neuroprotective effects in NMDA-injected CD-1 mice, delays the onset and progression of the amyotrophic lateral sclerosis (ALS) disease in SOD1 transgenic mice, and, after the onset of ALS, it increases the survival of motor neurons in the SC by 60%. The survival of telomerase-expressing cells (i.e. motor neurons), but not telomerase-deficient cells, exposed to oxidative stress was increased by AGS-499 treatment, suggesting that the AGS-499 effects are telomerase-mediated. Therefore, a controlled and transient increase in telomerase expression and activity in the brain by AGS-499 may exert neuroprotective effects.
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Affiliation(s)
- Erez Eitan
- The Shraga Segal Department of Immunology and Microbiology, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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23
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Beharier O, Dror S, Levy S, Kahn J, Mor M, Etzion S, Gitler D, Katz A, Muslin AJ, Moran A, Etzion Y. ZnT-1 protects HL-1 cells from simulated ischemia–reperfusion through activation of Ras–ERK signaling. J Mol Med (Berl) 2011; 90:127-38. [DOI: 10.1007/s00109-011-0845-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 12/04/2011] [Accepted: 12/06/2011] [Indexed: 01/19/2023]
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24
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Orenbuch A, Ayelet O, Shulman Y, Yoav S, Lipstein N, Noa L, Bechar A, Amit B, Lavy Y, Yotam L, Brumer E, Eliaz B, Vasileva M, Mariya V, Kahn J, Joy K, Barki-Harrington L, Liza BH, Kuner T, Thomas K, Gitler D, Daniel G. Inhibition of exocytosis or endocytosis blocks activity-dependent redistribution of synapsin. J Neurochem 2011; 120:248-58. [PMID: 22066784 DOI: 10.1111/j.1471-4159.2011.07579.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The synaptic vesicle cycle encompasses the pre-synaptic events that drive neurotransmission. Influx of calcium leads to the fusion of synaptic vesicles with the plasma membrane and the release of neurotransmitter, closely followed by endocytosis. Vacated release sites are repopulated with vesicles which are then primed for release. When activity is intense, reserve vesicles may be mobilized to counteract an eventual decline in transmission. Recently, interplay between endocytosis and repopulation of the readily releasable pool of vesicles has been identified. In this study, we show that exo-endocytosis is necessary to enable detachment of synapsin from reserve pool vesicles during synaptic activity. We report that blockage of exocytosis in cultured mouse hippocampal neurons, either by tetanus toxin or by the deletion of munc13, inhibits the activity-dependent redistribution of synapsin from the pre-synaptic terminal into the axon. Likewise, perturbation of endocytosis with dynasore or by a dynamin dominant-negative mutant fully prevents synapsin redistribution. Such inhibition of synapsin redistribution occurred despite the efficient phosphorylation of synapsin at its protein kinase A/CaMKI site, indicating that disengagement of synapsin from the vesicles requires exocytosis and endocytosis in addition to phosphorylation. Our results therefore reveal hitherto unidentified feedback within the synaptic vesicle cycle involving the synapsin-managed reserve pool.
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Affiliation(s)
- Ayelet Orenbuch
- Department of Physiology and Neurobiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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Levy S, Wilms CD, Brumer E, Kahn J, Pnueli L, Arava Y, Eilers J, Gitler D. SpRET: highly sensitive and reliable spectral measurement of absolute FRET efficiency. Microsc Microanal 2011; 17:176-90. [PMID: 21333032 DOI: 10.1017/s1431927610094493] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Contemporary research aims to understand biological processes not only by identifying participating proteins, but also by characterizing the dynamics of their interactions. Because Förster's Resonance Energy Transfer (FRET) is invaluable for the latter undertaking, its usage is steadily increasing. However, FRET measurements are notoriously error-prone, especially when its inherent efficiency is low, a not uncommon situation. Furthermore, many FRET methods are either difficult to implement, are not appropriate for observation of cellular dynamics, or report instrument-specific indices that hamper communication of results within the scientific community. We present here a novel comprehensive spectral methodology, SpRET, which substantially increases both the reliability and sensitivity of FRET microscopy, even under unfavorable conditions such as weak fluorescence or the presence of noise. While SpRET overcomes common pitfalls such as interchannel crosstalk and direct excitation of the acceptor, it also excels in removal of autofluorescence or background contaminations and in correcting chromatic aberrations, often overlooked factors that severely undermine FRET experiments. Finally, SpRET quantitatively reports absolute rather than relative FRET efficiency values, as well as the acceptor-to-donor molar ratio, which is critical for full and proper interpretation of FRET experiments. Thus, SpRET serves as an advanced, improved, and powerful tool in the cell biologist's toolbox.
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Affiliation(s)
- Shiri Levy
- Department of Physiology and Neurobiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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26
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Levy S, Beharier O, Etzion Y, Mor M, Buzaglo L, Shaltiel L, Gheber LA, Kahn J, Muslin AJ, Katz A, Gitler D, Moran A. Molecular basis for zinc transporter 1 action as an endogenous inhibitor of L-type calcium channels. J Biol Chem 2009; 284:32434-43. [PMID: 19767393 DOI: 10.1074/jbc.m109.058842] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The L-type calcium channel (LTCC) has a variety of physiological roles that are critical for the proper function of many cell types and organs. Recently, a member of the zinc-regulating family of proteins, ZnT-1, was recognized as an endogenous inhibitor of the LTCC, but its mechanism of action has not been elucidated. In the present study, using two-electrode voltage clamp recordings in Xenopus oocytes, we demonstrate that ZnT-1-mediated inhibition of the LTCC critically depends on the presence of the LTCC regulatory beta-subunit. Moreover, the ZnT-1-induced inhibition of the LTCC current is also abolished by excess levels of the beta-subunit. An interaction between ZnT-1 and the beta-subunit, as demonstrated by co-immunoprecipitation and by fluorescence resonance energy transfer, is consistent with this result. Using surface biotinylation and total internal reflection fluorescence microscopy in HEK293 cells, we show a ZnT-1-dependent decrease in the surface expression of the pore-forming alpha(1)-subunit of the LTCC. Similarly, a decrease in the surface expression of the alpha(1)-subunit is observed following up-regulation of the expression of endogenous ZnT-1 in rapidly paced cultured cardiomyocytes. We conclude that ZnT-1-mediated inhibition of the LTCC is mediated through a functional interaction of ZnT-1 with the LTCC beta-subunit and that it involves a decrease in the trafficking of the LTCC alpha(1)-subunit to the surface membrane.
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Affiliation(s)
- Shiri Levy
- Department of Physiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84101, Israel
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27
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Shmelzer Z, Karter M, Eisenstein M, Leto TL, Hadad N, Ben-Menahem D, Gitler D, Banani S, Wolach B, Rotem M, Levy R. Cytosolic Phospholipase A2α Is Targeted to the p47 -PX Domain of the Assembled NADPH Oxidase via a Novel Binding Site in Its C2 Domain. J Biol Chem 2008; 283:31898-908. [DOI: 10.1074/jbc.m804674200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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28
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Venton BJ, Seipel AT, Phillips PEM, Wetsel WC, Gitler D, Greengard P, Augustine GJ, Wightman RM. Cocaine increases dopamine release by mobilization of a synapsin-dependent reserve pool. J Neurosci 2006; 26:3206-9. [PMID: 16554471 PMCID: PMC6674099 DOI: 10.1523/jneurosci.4901-04.2006] [Citation(s) in RCA: 185] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cocaine primarily exerts its behavioral effects by enhancing dopaminergic neurotransmission, amplifying dopamine-encoded sensorimotor integration. The presumed mechanism for this effect is inhibition of the dopamine transporter, which blocks dopamine uptake and prolongs the duration of dopamine in the extracellular space. However, there is growing evidence that cocaine can also augment dopamine release. Here, we directly monitored the actions of cocaine on dopamine release by using electrochemical detection to measure extracellular dopamine in the striatum of anesthetized mice. Cocaine enhanced the levels of striatal dopamine produced by electrical stimulation of dopaminergic neurons. Even after pretreatment with alpha-methyl-p-tyrosine, which depletes the readily releasable pool of dopamine, cocaine was still capable of elevating dopamine levels. This suggests that cocaine enhances dopamine release by mobilizing a reserve pool of dopamine-containing synaptic vesicles. To test this hypothesis, we examined electrically evoked dopamine release in synapsin I/II/III triple knock-out mice, which have impaired synaptic vesicle reserve pools. Knock-out of synapsins greatly reduced the ability of cocaine to enhance dopamine release with long stimulus trains or after depletion of the newly synthesized pool. We therefore conclude that cocaine enhances dopamine release and does so by mobilizing a synapsin-dependent reserve pool of dopamine-containing synaptic vesicles. This capacity to enhance exocytotic release of dopamine may be important for the psychostimulant actions of cocaine.
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29
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Gitler D, Takagishi Y, Feng J, Ren Y, Rodriguiz RM, Wetsel WC, Greengard P, Augustine GJ. Different presynaptic roles of synapsins at excitatory and inhibitory synapses. J Neurosci 2005; 24:11368-80. [PMID: 15601943 PMCID: PMC6730366 DOI: 10.1523/jneurosci.3795-04.2004] [Citation(s) in RCA: 267] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The functions of synapsins were examined by characterizing the phenotype of mice in which all three synapsin genes were knocked out. Although these triple knock-out mice were viable and had normal brain anatomy, they exhibited a number of behavioral defects. Synaptic transmission was altered in cultured neurons from the hippocampus of knock-out mice. At excitatory synapses, loss of synapsins did not affect basal transmission evoked by single stimuli but caused a threefold increase in the rate of synaptic depression during trains of stimuli. This suggests that synapsins regulate the reserve pool of synaptic vesicles. This possibility was examined further by measuring synaptic vesicle density in living neurons transfected with green fluorescent protein-tagged synaptobrevin 2, a marker of synaptic vesicles. The relative amount of fluorescent synaptobrevin was substantially lower at synapses of knock-out neurons than of wild-type neurons. Electron microscopy also revealed a parallel reduction in the number of vesicles in the reserve pool of vesicles >150 nm away from the active zone at excitatory synapses. Thus, synapsins are required for maintaining vesicles in the reserve pool at excitatory synapses. In contrast, basal transmission at inhibitory synapses was reduced by loss of synapsins, but the kinetics of synaptic depression were unaffected. In these terminals, there was a mild reduction in the total number of synaptic vesicles, but this was not restricted to the reserve pool of vesicles. Thus, synapsins maintain the reserve pool of glutamatergic vesicles but regulate the size of the readily releasable pool of GABAergic vesicles.
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Affiliation(s)
- Daniel Gitler
- Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Abstract
Although synapsins are abundant synaptic vesicle proteins that are widely used as markers of presynaptic terminals, the mechanisms that target synapsins to presynaptic terminals have not been elucidated. We have addressed this question by imaging the targeting of green fluorescent protein-tagged synapsins in cultured hippocampal neurons. Whereas all synapsin isoforms targeted robustly to presynaptic terminals in wild-type neurons, synapsin Ib scarcely targeted in neurons in which all synapsins were knocked-out. Coexpression of other synapsin isoforms significantly strengthened the targeting of synapsin Ib in knock-out neurons, indicating that heterodimerization is required for synapsin Ib to target. Truncation mutagenesis revealed that synapsin Ia targets via distributed binding sites that include domains B, C, and E. Although domain A was not necessary for targeting, its presence enhanced targeting. Domain D inhibited targeting, but this inhibition was overcome by domain E. Thus, multiple intermolecular and intramolecular interactions are required for synapsins to target to presynaptic terminals.
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Affiliation(s)
- Daniel Gitler
- Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Spira ME, Oren R, Dormann A, Gitler D. Critical calpain-dependent ultrastructural alterations underlie the transformation of an axonal segment into a growth cone after axotomy of cultured Aplysia neurons. J Comp Neurol 2003; 457:293-312. [PMID: 12541311 DOI: 10.1002/cne.10569] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The transformation of a stable axonal segment into a motile growth cone is a critical step in the regeneration of amputated axons. In earlier studies we found that axotomy of cultured Aplysia neurons leads to a transient and local elevation of the free intracellular Ca2+ concentration, resulting in calpain activation, localized proteolysis of submembranal spectrin, and, eventually, growth cone formation. Moreover, inhibition of calpain by calpeptin prior to axotomy inhibits growth cone formation. Here we investigated the mechanisms by which calpain activation participates in the transformation of an axonal segment into a growth cone. To that end we compared the ultrastructural alterations induced by axotomy performed under control conditions with those caused by axotomy performed in the presence of calpeptin, using cultured Aplysia neurons as a model. We identified the critical calpain-dependent cytoarchitectural alterations that underlie the formation of a growth cone after axotomy. Calpain-dependent processes lead to restructuring of the neurofilaments and microtubules to form an altered cytoskeletal region 50-150 microm proximal to the tip of the transected axon in which vesicles accumulate. The dense pool of vesicles forms in close proximity to a segment of the plasma membrane along which the spectrin membrane skeleton has been proteolyzed by calpain. We suggest that the rearrangement of the cytoskeleton forms a transient cellular compartment that traps transported vesicles and serves as a locus for microtubule polymerization. We propose that this cytoskeletal configuration facilitates the fusion of vesicles with the plasma membrane, promoting the extension of the growth cone's lamellipodium. The growth process is further supported by the radial polymerization of microtubules from the growth cone's center.
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Affiliation(s)
- Micha E Spira
- Department of Neurobiology, Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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32
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Abstract
Our laboratory has established that local activation of calpain by a transient elevation of the free intracellular calcium concentration is crucial for the induction of growth cone (GC) formation in cultured Aplysia neurons. The mechanisms and stages in which calpain is involved in the formation of a GC are not known. We began to study these questions by determining the nature of calpain's action and the stages in which calpain activity affects the cascade of events that leads to the formation of the GC and its extension. We report that the calpain-dependent transformation of an axonal segment into a GC occurs within a narrow window of opportunity that lasts approximately 5 min. If calpain is inhibited during this window of opportunity, GC formation does not occur. Inhibition of calpain after the window of opportunity slows down the rate of lamellipodial extension but doesn't arrest it. The proteolysis of spectrin, a calpain substrate and a major component of the membrane skeleton, occurs within this window of opportunity, in agreement with the hypothesis that spectrin proteolysis is an early step in the formation of the GC. If the onset of proteolysis is deferred, spectrin remains unchanged and GC formation is compromised. We suggest that calpain participates in two different processes: it is critical for the triggering of GC formation and plays a modulatory role during the extension of the GC's lamellipodia.
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Affiliation(s)
- Daniel Gitler
- Department of Neurobiology, Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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Abstract
The emergence of a neuronal growth cone from a transected axon is a necessary step in the sequence of events that leads to successful regeneration. Yet, the molecular mechanisms underlying its formation after axotomy are unknown. In this study, we show by real time imaging of the free intracellular Ca2+ concentration, of proteolytic activity, and of growth cone formation that the activation of localized and transient Ca2+-dependent proteolysis is a necessary step in the cascade of events that leads to growth cone formation. Inhibition of this proteolytic activity by calpeptin, a calpain inhibitor, abolishes growth cone formation. We suggest that calpain plays a central role in the reorganization of the axon's cytoskeleton during its transition from a stable differentiated structure into a dynamically extending growth cone.
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Affiliation(s)
- D Gitler
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University of Jerusalem, Israel
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Spira ME, Dormann A, Ashery U, Gabso M, Gitler D, Benbassat D, Oren R, Ziv NE. Use of Aplysia neurons for the study of cellular alterations and the resealing of transected axons in vitro. J Neurosci Methods 1996; 69:91-102. [PMID: 8912939 DOI: 10.1016/s0165-0270(96)00024-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The present report describes the experimental advantages offered by the combined use of Aplysia neurons and contemporary techniques to analyze the cellular events associated with nerve injury in the form of axotomy. The experiments were performed by transecting, under visual control, the main axon of identified Aplysia neurons in primary culture while monitoring several related parameters. We found that in cultured Aplysia neurons axotomy leads to the elevation of the [Ca2+]i in both the proximal and distal axonal segments from a resting level of 100 nM up to the millimolar range for a duration of 3-5 min. This increase in [Ca2+]i led to identical alterations in the cytoarchitecture of the proximal and distal segments. The formation of a membrane seal over the transected ends by their constriction and the subsequent fusion of the membrane is a [Ca2+]i-dependent process and is triggered by the elevation of [Ca2+]i to the microM level. Seal formation was followed by down-regulation of the [Ca2+]i to control levels. Following the formation of the membrane seal an increase in membrane retrieval was observed. We hypothesize that the retrieved membrane serves as an immediately available membrane reservoir for growth cone extension.
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Affiliation(s)
- M E Spira
- Dept. of Neurobiology, Life Sciences Institute, The Hebrew University of Jerusalem, Israel
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Affiliation(s)
- V Bengualid
- Department of Infectious Disease, St. Barnabas Hospital, Bronx, New York 10457-2594, USA
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36
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Gitler D. Utilization of rehabilitation research: implications for applying medical technology. J Health Hum Resour Adm 1983; 5:71-9. [PMID: 10258785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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