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López-Hernández T, Takenaka KI, Mori Y, Kongpracha P, Nagamori S, Haucke V, Takamori S. Clathrin-independent endocytic retrieval of SV proteins mediated by the clathrin adaptor AP-2 at mammalian central synapses. eLife 2022; 11:e71198. [PMID: 35014951 PMCID: PMC8752090 DOI: 10.7554/elife.71198] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 12/28/2021] [Indexed: 12/25/2022] Open
Abstract
Neurotransmission is based on the exocytic fusion of synaptic vesicles (SVs) followed by endocytic membrane retrieval and the reformation of SVs. Conflicting models have been proposed regarding the mechanisms of SV endocytosis, most notably clathrin/adaptor protein complex 2 (AP-2)-mediated endocytosis and clathrin-independent ultrafast endocytosis. Partitioning between these pathways has been suggested to be controlled by temperature and stimulus paradigm. We report on the comprehensive survey of six major SV proteins to show that SV endocytosis in mouse hippocampal neurons at physiological temperature occurs independent of clathrin while the endocytic retrieval of a subset of SV proteins including the vesicular transporters for glutamate and GABA depend on sorting by the clathrin adaptor AP-2. Our findings highlight a clathrin-independent role of the clathrin adaptor AP-2 in the endocytic retrieval of select SV cargos from the presynaptic cell surface and suggest a revised model for the endocytosis of SV membranes at mammalian central synapses.
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Affiliation(s)
| | - Koh-ichiro Takenaka
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha UniversityKyotoJapan
| | - Yasunori Mori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha UniversityKyotoJapan
| | - Pornparn Kongpracha
- Department of Laboratory Medicine, The Jikei University School of MedicineTokyoJapan
| | - Shushi Nagamori
- Department of Laboratory Medicine, The Jikei University School of MedicineTokyoJapan
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)BerlinGermany
| | - Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha UniversityKyotoJapan
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SNT-1 Functions as the Ca 2+ Sensor for Tonic and Evoked Neurotransmitter Release in Caenorhabditis Elegans. J Neurosci 2018; 38:5313-5324. [PMID: 29760174 DOI: 10.1523/jneurosci.3097-17.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 04/23/2018] [Accepted: 05/03/2018] [Indexed: 12/23/2022] Open
Abstract
Synaptotagmin-1 (Syt1) binds Ca2+ through its tandem C2 domains (C2A and C2B) and triggers Ca2+-dependent neurotransmitter release. Here, we show that snt-1, the homolog of mammalian Syt1, functions as the Ca2+ sensor for both tonic and evoked neurotransmitter release at the Caenorhabditis elegans neuromuscular junction. Mutations that disrupt Ca2+ binding in double C2 domains of SNT-1 significantly impaired tonic release, whereas disrupting Ca2+ binding in a single C2 domain had no effect, indicating that the Ca2+ binding of the two C2 domains is functionally redundant for tonic release. Stimulus-evoked release was significantly reduced in snt-1 mutants, with prolonged release latency as well as faster rise and decay kinetics. Unlike tonic release, evoked release was triggered by Ca2+ binding solely to the C2B domain. Moreover, we showed that SNT-1 plays an essential role in the priming process in different subpopulations of synaptic vesicles with tight or loose coupling to Ca2+ entry.SIGNIFICANCE STATEMENT We showed that SNT-1 in Caenorhabditis elegans regulates evoked neurotransmitter release through Ca2+ binding to its C2B domain in a similar way to Syt1 in the mouse CNS and the fly neuromuscular junction. However, the largely decreased tonic release in snt-1 mutants argues SNT-1 has a clamping function. Indeed, Ca2+-binding mutations in the C2 domains in SNT-1 significantly reduced the frequency of the miniature EPSC, indicating that SNT-1 also acts as a Ca2+ sensor for tonic release. Therefore, revealing the differential mechanisms between invertebrates and vertebrates will provide significant insights into our understanding how synaptic vesicle fusion is regulated.
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Maritzen T, Haucke V. Coupling of exocytosis and endocytosis at the presynaptic active zone. Neurosci Res 2018; 127:45-52. [DOI: 10.1016/j.neures.2017.09.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/13/2017] [Accepted: 08/25/2017] [Indexed: 01/08/2023]
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Robinson MS. Forty Years of Clathrin-coated Vesicles. Traffic 2015; 16:1210-38. [PMID: 26403691 DOI: 10.1111/tra.12335] [Citation(s) in RCA: 230] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 09/16/2015] [Accepted: 09/16/2015] [Indexed: 12/11/2022]
Abstract
The purification of coated vesicles and the discovery of clathrin by Barbara Pearse in 1975 was a landmark in cell biology. Over the past 40 years, work from many labs has uncovered the molecular details of clathrin and its associated proteins, including how they assemble into a coated vesicle and how they select cargo. Unexpected connections have been found with signalling, development, neuronal transmission, infection, immunity and genetic disorders. But there are still a number of unanswered questions, including how clathrin-mediated trafficking is regulated and how the machinery evolved.
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Affiliation(s)
- Margaret S Robinson
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
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Kononenko NL, Diril MK, Puchkov D, Kintscher M, Koo SJ, Pfuhl G, Winter Y, Wienisch M, Klingauf J, Breustedt J, Schmitz D, Maritzen T, Haucke V. Compromised fidelity of endocytic synaptic vesicle protein sorting in the absence of stonin 2. Proc Natl Acad Sci U S A 2013; 110:E526-35. [PMID: 23345427 PMCID: PMC3568307 DOI: 10.1073/pnas.1218432110] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neurotransmission depends on the exocytic fusion of synaptic vesicles (SVs) and their subsequent reformation either by clathrin-mediated endocytosis or budding from bulk endosomes. How synapses are able to rapidly recycle SVs to maintain SV pool size, yet preserve their compositional identity, is poorly understood. We demonstrate that deletion of the endocytic adaptor stonin 2 (Stn2) in mice compromises the fidelity of SV protein sorting, whereas the apparent speed of SV retrieval is increased. Loss of Stn2 leads to selective missorting of synaptotagmin 1 to the neuronal surface, an elevated SV pool size, and accelerated SV protein endocytosis. The latter phenotype is mimicked by overexpression of endocytosis-defective variants of synaptotagmin 1. Increased speed of SV protein retrieval in the absence of Stn2 correlates with an up-regulation of SV reformation from bulk endosomes. Our results are consistent with a model whereby Stn2 is required to preserve SV protein composition but is dispensable for maintaining the speed of SV recycling.
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Affiliation(s)
- Natalia L. Kononenko
- Department of Molecular Pharmacology and Cell Biology, Leibniz Institut für Molekulare Pharmakologie, 13125 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Berlin, 10117 Berlin, Germany
| | - M. Kasim Diril
- Freie Universität Berlin, Institut für Chemie und Biochemie, 14195 Berlin, Germany
| | - Dmytro Puchkov
- Department of Molecular Pharmacology and Cell Biology, Leibniz Institut für Molekulare Pharmakologie, 13125 Berlin, Germany
| | - Michael Kintscher
- NeuroCure Cluster of Excellence, Charité Berlin, 10117 Berlin, Germany
| | - Seong Joo Koo
- Department of Molecular Pharmacology and Cell Biology, Leibniz Institut für Molekulare Pharmakologie, 13125 Berlin, Germany
| | - Gerit Pfuhl
- Department of Cognitive Neurobiology, Humboldt Universität zu Berlin, 10117 Berlin, Germany; and
| | - York Winter
- Department of Cognitive Neurobiology, Humboldt Universität zu Berlin, 10117 Berlin, Germany; and
| | - Martin Wienisch
- Institute for Medical Physics and Biophysics, University of Münster, 48149 Münster, Germany
| | - Jürgen Klingauf
- Institute for Medical Physics and Biophysics, University of Münster, 48149 Münster, Germany
| | - Jörg Breustedt
- NeuroCure Cluster of Excellence, Charité Berlin, 10117 Berlin, Germany
| | - Dietmar Schmitz
- NeuroCure Cluster of Excellence, Charité Berlin, 10117 Berlin, Germany
| | - Tanja Maritzen
- Department of Molecular Pharmacology and Cell Biology, Leibniz Institut für Molekulare Pharmakologie, 13125 Berlin, Germany
| | - Volker Haucke
- Department of Molecular Pharmacology and Cell Biology, Leibniz Institut für Molekulare Pharmakologie, 13125 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Berlin, 10117 Berlin, Germany
- Freie Universität Berlin, Institut für Chemie und Biochemie, 14195 Berlin, Germany
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Mullen GP, Grundahl KM, Gu M, Watanabe S, Hobson RJ, Crowell JA, McManus JR, Mathews EA, Jorgensen EM, Rand JB. UNC-41/stonin functions with AP2 to recycle synaptic vesicles in Caenorhabditis elegans. PLoS One 2012; 7:e40095. [PMID: 22808098 PMCID: PMC3393740 DOI: 10.1371/journal.pone.0040095] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 05/31/2012] [Indexed: 11/20/2022] Open
Abstract
The recycling of synaptic vesicles requires the recovery of vesicle proteins and membrane. Members of the stonin protein family (Drosophila Stoned B, mammalian stonin 2) have been shown to link the synaptic vesicle protein synaptotagmin to the endocytic machinery. Here we characterize the unc-41 gene, which encodes the stonin ortholog in the nematode Caenorhabditis elegans. Transgenic expression of Drosophila stonedB rescues unc-41 mutant phenotypes, demonstrating that UNC-41 is a bona fide member of the stonin family. In unc-41 mutants, synaptotagmin is present in axons, but is mislocalized and diffuse. In contrast, UNC-41 is localized normally in synaptotagmin mutants, demonstrating a unidirectional relationship for localization. The phenotype of snt-1 unc-41 double mutants is stronger than snt-1 mutants, suggesting that UNC-41 may have additional, synaptotagmin-independent functions. We also show that unc-41 mutants have defects in synaptic vesicle membrane endocytosis, including a ∼50% reduction of vesicles in both acetylcholine and GABA motor neurons. These endocytic defects are similar to those observed in apm-2 mutants, which lack the µ2 subunit of the AP2 adaptor complex. However, no further reduction in synaptic vesicles was observed in unc-41 apm-2 double mutants, suggesting that UNC-41 acts in the same endocytic pathway as µ2 adaptin.
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Affiliation(s)
- Gregory P. Mullen
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
| | - Kiely M. Grundahl
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
| | - Mingyu Gu
- Howard Hughes Medical Institute and Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
| | - Shigeki Watanabe
- Howard Hughes Medical Institute and Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
| | - Robert J. Hobson
- Howard Hughes Medical Institute and Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
| | - John A. Crowell
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
| | - John R. McManus
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
| | - Eleanor A. Mathews
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
| | - Erik M. Jorgensen
- Howard Hughes Medical Institute and Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
| | - James B. Rand
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
- * E-mail:
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Soekmadji C, Angkawidjaja C, Kelly LE. Ca2+ regulates the Drosophila Stoned-A and Stoned-B proteins interaction with the C2B domain of Synaptotagmin-1. PLoS One 2012; 7:e38822. [PMID: 22701718 PMCID: PMC3373503 DOI: 10.1371/journal.pone.0038822] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 05/11/2012] [Indexed: 02/02/2023] Open
Abstract
The dicistronic Drosophila stoned gene is involved in exocytosis and/or endocytosis of synaptic vesicles. Mutations in either stonedA or stonedB cause a severe disruption of neurotransmission in fruit flies. Previous studies have shown that the coiled-coil domain of the Stoned-A and the µ-homology domain of the Stoned-B protein can interact with the C2B domain of Synaptotagmin-1. However, very little is known about the mechanism of interaction between the Stoned proteins and the C2B domain of Synaptotagmin-1. Here we report that these interactions are increased in the presence of Ca(2+). The Ca(2+)-dependent interaction between the µ-homology domain of Stoned-B and C2B domain of Synaptotagmin-1 is affected by phospholipids. The C-terminal region of the C2B domain, including the tryptophan-containing motif, and the Ca(2+) binding loop region that modulate the Ca(2+)-dependent oligomerization, regulates the binding of the Stoned-A and Stoned-B proteins to the C2B domain. Stoned-B, but not Stoned-A, interacts with the Ca(2+)-binding loop region of C2B domain. The results indicate that Ca(2+)-induced self-association of the C2B domain regulates the binding of both Stoned-A and Stoned-B proteins to Synaptotagmin-1. The Stoned proteins may regulate sustainable neurotransmission in vivo by binding to Ca(2+)-bound Synaptotagmin-1 associated synaptic vesicles.
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Affiliation(s)
- Carolina Soekmadji
- Department of Genetics, The University of Melbourne, Parkville, Victoria, Australia.
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100 years of Drosophila research and its impact on vertebrate neuroscience: a history lesson for the future. Nat Rev Neurosci 2011; 11:514-22. [PMID: 20383202 DOI: 10.1038/nrn2839] [Citation(s) in RCA: 272] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Discoveries in fruit flies have greatly contributed to our understanding of neuroscience. The use of an unparalleled wealth of tools, many of which originated between 1910–1960, has enabled milestone discoveries in nervous system development and function. Such findings have triggered and guided many research efforts in vertebrate neuroscience. After 100 years, fruit flies continue to be the choice model system for many neuroscientists. The combinational use of powerful research tools will ensure that this model organism will continue to lead to key discoveries that will impact vertebrate neuroscience.
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Rao Y, Rückert C, Saenger W, Haucke V. The early steps of endocytosis: from cargo selection to membrane deformation. Eur J Cell Biol 2011; 91:226-33. [PMID: 21458101 DOI: 10.1016/j.ejcb.2011.02.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 02/11/2011] [Accepted: 02/13/2011] [Indexed: 10/18/2022] Open
Abstract
Clathrin-mediated endocytosis mediates the internalization of signaling and nutrient receptors, ion channels and regulates the endocytic recycling of pre- and postsynaptic membrane proteins. During early stages endocytic adaptors recognize sorting signals within this diverse array of cargo proteins destined for internalization. Cargo sequestration is mechanistically coupled to membrane deformation, a process involving BAR domain proteins, resulting in the generation of endocytic intermediates that finally undergo dynamin-mediated fission. Here we summarize recent insights gathered from a combination of structural, biochemical, and cell biological studies that have revealed a remarkable complexity of the machinery for endocytic sorting and membrane deformation.
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Affiliation(s)
- Yijian Rao
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany
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