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Wei L, Guo X, Haimov E, Obashi K, Lee SH, Shin W, Sun M, Chan CY, Sheng J, Zhang Z, Mohseni A, Ghosh Dastidar S, Wu XS, Wang X, Han S, Arpino G, Shi B, Molakarimi M, Matthias J, Wurm CA, Gan L, Taraska JW, Kozlov MM, Wu LG. Clathrin mediates membrane fission and budding by constricting membrane pores. Cell Discov 2024; 10:62. [PMID: 38862506 PMCID: PMC11166961 DOI: 10.1038/s41421-024-00677-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 04/04/2024] [Indexed: 06/13/2024] Open
Abstract
Membrane budding, which underlies fundamental processes like endocytosis, intracellular trafficking, and viral infection, is thought to involve membrane coat-forming proteins, including the most observed clathrin, to form Ω-shape profiles and helix-forming proteins like dynamin to constrict Ω-profiles' pores and thus mediate fission. Challenging this fundamental concept, we report that polymerized clathrin is required for Ω-profiles' pore closure and that clathrin around Ω-profiles' base/pore region mediates pore constriction/closure in neuroendocrine chromaffin cells. Mathematical modeling suggests that clathrin polymerization at Ω-profiles' base/pore region generates forces from its intrinsically curved shape to constrict/close the pore. This new fission function may exert broader impacts than clathrin's well-known coat-forming function during clathrin (coat)-dependent endocytosis, because it underlies not only clathrin (coat)-dependent endocytosis, but also diverse endocytic modes, including ultrafast, fast, slow, bulk, and overshoot endocytosis previously considered clathrin (coat)-independent in chromaffin cells. It mediates kiss-and-run fusion (fusion pore closure) previously considered bona fide clathrin-independent, and limits the vesicular content release rate. Furthermore, analogous to results in chromaffin cells, we found that clathrin is essential for fast and slow endocytosis at hippocampal synapses where clathrin was previously considered dispensable, suggesting clathrin in mediating synaptic vesicle endocytosis and fission. These results suggest that clathrin and likely other intrinsically curved coat proteins are a new class of fission proteins underlying vesicle budding and fusion. The half-a-century concept and studies that attribute vesicle-coat contents' function to Ω-profile formation and classify budding as coat-protein (e.g., clathrin)-dependent or -independent may need to be re-defined and re-examined by considering clathrin's pivotal role in pore constriction/closure.
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Affiliation(s)
- Lisi Wei
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Xiaoli Guo
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Ehud Haimov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel
| | - Kazuki Obashi
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD, USA
| | - Sung Hoon Lee
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
- Chung-Ang University, Seoul, Republic of Korea
| | - Wonchul Shin
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Min Sun
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Chung Yu Chan
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Jiansong Sheng
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
- 900 Clopper Rd, Suite, 130, Gaithersburg, MD, USA
| | - Zhen Zhang
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
- Center of Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Ammar Mohseni
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | | | - Xin-Sheng Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Xin Wang
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Sue Han
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Gianvito Arpino
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
- Emme 3 Srl - Via Luigi Meraviglia, 31 - 20020, Lainate, MI, Italy
| | - Bo Shi
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Maryam Molakarimi
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | | | | | - Lin Gan
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - Justin W Taraska
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD, USA
| | - Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel.
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
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Fernández-Infante C, Hernández-Cano L, Herranz Ó, Berrocal P, Sicilia-Navarro C, González-Porras JR, Bastida JM, Porras A, Guerrero C. Platelet C3G: a key player in vesicle exocytosis, spreading and clot retraction. Cell Mol Life Sci 2024; 81:84. [PMID: 38345631 PMCID: PMC10861696 DOI: 10.1007/s00018-023-05109-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 12/22/2023] [Accepted: 12/23/2023] [Indexed: 02/15/2024]
Abstract
C3G is a Rap1 GEF that plays a pivotal role in platelet-mediated processes such as angiogenesis, tumor growth, and metastasis by modulating the platelet secretome. Here, we explore the mechanisms through which C3G governs platelet secretion. For this, we utilized animal models featuring either overexpression or deletion of C3G in platelets, as well as PC12 cell clones expressing C3G mutants. We found that C3G specifically regulates α-granule secretion via PKCδ, but it does not affect δ-granules or lysosomes. C3G activated RalA through a GEF-dependent mechanism, facilitating vesicle docking, while interfering with the formation of the trans-SNARE complex, thereby restricting vesicle fusion. Furthermore, C3G promotes the formation of lamellipodia during platelet spreading on specific substrates by enhancing actin polymerization via Src and Rac1-Arp2/3 pathways, but not Rap1. Consequently, C3G deletion in platelets favored kiss-and-run exocytosis. C3G also controlled granule secretion in PC12 cells, including pore formation. Additionally, C3G-deficient platelets exhibited reduced phosphatidylserine exposure, resulting in decreased thrombin generation, which along with defective actin polymerization and spreading, led to impaired clot retraction. In summary, platelet C3G plays a dual role by facilitating platelet spreading and clot retraction through the promotion of outside-in signaling while concurrently downregulating α-granule secretion by restricting granule fusion.
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Affiliation(s)
- Cristina Fernández-Infante
- Instituto de Biología Molecular y Celular del Cáncer (IMBCC), USAL-CSIC, Centro de Investigación del Cáncer, Campus Unamuno S/N, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain
- Departamento de Medicina, Universidad de Salamanca, Salamanca, Spain
| | - Luis Hernández-Cano
- Instituto de Biología Molecular y Celular del Cáncer (IMBCC), USAL-CSIC, Centro de Investigación del Cáncer, Campus Unamuno S/N, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain
- Departamento de Medicina, Universidad de Salamanca, Salamanca, Spain
| | - Óscar Herranz
- Instituto de Biología Molecular y Celular del Cáncer (IMBCC), USAL-CSIC, Centro de Investigación del Cáncer, Campus Unamuno S/N, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain
- Departamento de Medicina, Universidad de Salamanca, Salamanca, Spain
| | - Pablo Berrocal
- Instituto de Biología Molecular y Celular del Cáncer (IMBCC), USAL-CSIC, Centro de Investigación del Cáncer, Campus Unamuno S/N, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain
- Departamento de Medicina, Universidad de Salamanca, Salamanca, Spain
| | - Carmen Sicilia-Navarro
- Instituto de Biología Molecular y Celular del Cáncer (IMBCC), USAL-CSIC, Centro de Investigación del Cáncer, Campus Unamuno S/N, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain
- Departamento de Medicina, Universidad de Salamanca, Salamanca, Spain
| | - José Ramón González-Porras
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain
- Departamento de Medicina, Universidad de Salamanca, Salamanca, Spain
- Servicio de Hematología, Hospital Universitario de Salamanca, Salamanca, Spain
| | - José María Bastida
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain
- Departamento de Medicina, Universidad de Salamanca, Salamanca, Spain
- Servicio de Hematología, Hospital Universitario de Salamanca, Salamanca, Spain
| | - Almudena Porras
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad Complutense de Madrid, Ciudad Universitaria, Madrid, Spain.
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain.
| | - Carmen Guerrero
- Instituto de Biología Molecular y Celular del Cáncer (IMBCC), USAL-CSIC, Centro de Investigación del Cáncer, Campus Unamuno S/N, Salamanca, Spain.
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain.
- Departamento de Medicina, Universidad de Salamanca, Salamanca, Spain.
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Song DY, Yuan L, Cui N, Feng C, Meng L, Wang XH, Xiang M, Liu D, Wang C, Zhang Z, Li JY, Li W. α-Synuclein induces deficiency in clathrin-mediated endocytosis through inhibiting synaptojanin1 expression. J Neurochem 2023; 167:461-484. [PMID: 37788328 DOI: 10.1111/jnc.15974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/13/2023] [Accepted: 09/13/2023] [Indexed: 10/05/2023]
Abstract
Parkinson's disease (PD) is an age-related chronic neurological disorder, mainly characterized by the pathological feature of α-synuclein (α-syn) aggregation, with the exact disease pathogenesis unclear. During the onset and progression of PD, synaptic dysfunction, including dysregulation of axonal transport, impaired exocytosis, and endocytosis are identified as crucial events of PD pathogenesis. It has been reported that over-expression of α-syn impairs clathrin-mediated endocytosis (CME) in the synapses. However, the underlying mechanisms still needs to be explored. In this study, we investigated the molecular events underlying the synaptic dysfunction caused by over-expression of wild-type human α-syn and its mutant form, involving series of proteins participating in CME. We found that excessive human α-syn causes impaired fission and uncoating of clathrin-coated vesicles during synaptic vesicle recycling, leading to reduced clustering of synaptic vesicles near the active zone and increased size of plasma membrane and number of endocytic intermediates. Furthermore, over-expressed human α-syn induced changes of CME-associated proteins, among which synaptojanin1 (SYNJ1) showed significant reduction in various brain regions. Over-expression of SYNJ1 in primary hippocampal neurons from α-syn transgenic mice recovered the synaptic vesicle density, clustering and endocytosis. Using fluorescence-conjugated transferrin, we demonstrated that SYNJ1 re-boosted the CME activity by restoring the phosphatidylinositol-4,5-bisphosphate homeostasis. Our data suggested that over-expression of α-syn disrupts synaptic function through interfering with vesicle recycling, which could be alleviated by re-availing of SYNJ1. Our study unrevealed a molecular mechanism of the synaptic dysfunction in PD pathogenesis and provided a potential therapeutic target for treating PD.
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Affiliation(s)
- Dong-Yan Song
- Institute of Neuroscience, College of Life and Health Sciences, Northeastern University, Shenyang, China
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
| | - Lin Yuan
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
| | - Na Cui
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
| | - Cong Feng
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
| | - Lanxia Meng
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Xin-He Wang
- Institute of Neuroscience, College of Life and Health Sciences, Northeastern University, Shenyang, China
| | - Man Xiang
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
| | - Di Liu
- Institute of Neuroscience, College of Life and Health Sciences, Northeastern University, Shenyang, China
| | - Chun Wang
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
| | - Zhentao Zhang
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Jia-Yi Li
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
- Neural Plasticity and Repair Unit, Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Wen Li
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
- Neural Plasticity and Repair Unit, Department of Experimental Medical Sciences, Lund University, Lund, Sweden
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Tanaka H, Funahashi J, Hirano T. Live-cell imaging of endocytosed synaptophysin around individual hippocampal presynaptic active zones. Front Cell Neurosci 2023; 17:1277729. [PMID: 37927445 PMCID: PMC10620501 DOI: 10.3389/fncel.2023.1277729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 10/06/2023] [Indexed: 11/07/2023] Open
Abstract
In presynaptic terminals 4 types of endocytosis, kiss-and-run, clathrin-mediated, bulk and ultrafast endocytosis have been reported to maintain repetitive exocytosis of neurotransmitter. However, detailed characteristics and relative contribution of each type of endocytosis still need to be determined. Our previous live-cell imaging study demonstrated individual exocytosis events of synaptic vesicle within an active-zone-like membrane (AZLM) formed on glass using synaptophysin tagged with a pH-sensitive fluorescent protein. On the other hand, individual endocytosis events of postsynaptic receptors were recorded with a rapid extracellular pH exchange method. Combining these methods, here we live-cell imaged endocytosed synaptophysin with total internal reflection fluorescence microscopy in rat hippocampal culture preparations. Clathrin-dependent and -independent endocytosis, which was seemingly bulk endocytosis, occurred within several seconds after electrical stimulation at multiple locations around AZLM at room temperature, with the locations varying trial to trial. The contribution of clathrin-independent endocytosis was more prominent when the number of stimulation pulses was large. The skewness of synaptophysin distribution in intracellular vesicles became smaller after addition of a clathrin inhibitor, which suggests that clathrin-dependent endocytosis concentrates synaptophysin. Ultrafast endocytosis was evident immediately after stimulation only at near physiological temperature and was the predominant endocytosis when the number of stimulation pulses was small.
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Affiliation(s)
- Hiromitsu Tanaka
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
- Department of Developmental Biology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Junichiro Funahashi
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Tomoo Hirano
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
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5
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Rizalar FS, Lucht MT, Petzoldt A, Kong S, Sun J, Vines JH, Telugu NS, Diecke S, Kaas T, Bullmann T, Schmied C, Löwe D, King JS, Cho W, Hallermann S, Puchkov D, Sigrist SJ, Haucke V. Phosphatidylinositol 3,5-bisphosphate facilitates axonal vesicle transport and presynapse assembly. Science 2023; 382:223-230. [PMID: 37824668 PMCID: PMC10938084 DOI: 10.1126/science.adg1075] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 08/16/2023] [Indexed: 10/14/2023]
Abstract
Neurons relay information via specialized presynaptic compartments for neurotransmission. Unlike conventional organelles, the specialized apparatus characterizing the neuronal presynapse must form de novo. How the components for presynaptic neurotransmission are transported and assembled is poorly understood. Our results show that the rare late endosomal signaling lipid phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2] directs the axonal cotransport of synaptic vesicle and active zone proteins in precursor vesicles in human neurons. Precursor vesicles are distinct from conventional secretory organelles, endosomes, and degradative lysosomes and are transported by coincident detection of PI(3,5)P2 and active ARL8 via kinesin KIF1A to the presynaptic compartment. Our findings identify a crucial mechanism that mediates the delivery of synaptic vesicle and active zone proteins to developing synapses.
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Affiliation(s)
- Filiz Sila Rizalar
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Max T. Lucht
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Astrid Petzoldt
- Department of Biology, Chemistry, Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
| | - Shuhan Kong
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Jiachen Sun
- Department of Chemistry, University of Illinois Chicago, Chicago, IL 60607, USA
| | - James H. Vines
- School of Biosciences, University of Sheffield, Firth Court Western Bank, Sheffield S10 2TN, UK
| | - Narasimha Swamy Telugu
- Max-Delbrück-Centrum für Molekulare Medizin (MDC), Technology Platform Pluripotent Stem Cells, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Sebastian Diecke
- Max-Delbrück-Centrum für Molekulare Medizin (MDC), Technology Platform Pluripotent Stem Cells, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Thomas Kaas
- Leipzig University, Carl-Ludwig-Institute of Physiology, Faculty of Medicine, 04103 Leipzig, Germany
| | - Torsten Bullmann
- Leipzig University, Carl-Ludwig-Institute of Physiology, Faculty of Medicine, 04103 Leipzig, Germany
| | - Christopher Schmied
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Delia Löwe
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Jason S. King
- School of Biosciences, University of Sheffield, Firth Court Western Bank, Sheffield S10 2TN, UK
| | - Wonhwa Cho
- Department of Chemistry, University of Illinois Chicago, Chicago, IL 60607, USA
| | - Stefan Hallermann
- Leipzig University, Carl-Ludwig-Institute of Physiology, Faculty of Medicine, 04103 Leipzig, Germany
| | - Dmytro Puchkov
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Stephan J. Sigrist
- Department of Biology, Chemistry, Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
- Department of Biology, Chemistry, Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
- Charité – Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
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6
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Shen Y, Wen Y, Sposini S, Vishwanath AA, Abdelfattah AS, Schreiter ER, Lemieux MJ, de Juan-Sanz J, Perrais D, Campbell RE. Rational Engineering of an Improved Genetically Encoded pH Sensor Based on Superecliptic pHluorin. ACS Sens 2023; 8:3014-3022. [PMID: 37481776 DOI: 10.1021/acssensors.3c00484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Genetically encoded pH sensors based on fluorescent proteins are valuable tools for the imaging of cellular events that are associated with pH changes, such as exocytosis and endocytosis. Superecliptic pHluorin (SEP) is a pH-sensitive green fluorescent protein (GFP) variant widely used for such applications. Here, we report the rational design, development, structure, and applications of Lime, an improved SEP variant with higher fluorescence brightness and greater pH sensitivity. The X-ray crystal structure of Lime supports the mechanistic rationale that guided the introduction of beneficial mutations. Lime provides substantial improvements relative to SEP for imaging of endocytosis and exocytosis. Furthermore, Lime and its variants are advantageous for a broader range of applications including the detection of synaptic release and neuronal voltage changes.
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Affiliation(s)
- Yi Shen
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Yurong Wen
- Department of Biochemistry, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
- Center for Microbiome Research of Med-X Institute, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, China
| | - Silvia Sposini
- CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, Bordeaux 33076, France
- Department of Metabolism, Digestion and Reproduction, Institute of Reproductive and Developmental Biology, Imperial College London, London SW7 2BX, United Kingdom
| | - Anjali Amrapali Vishwanath
- Institut du Cerveau-Paris Brain Institute-ICM, Inserm, CNRS, APHP, Häpital de la Pitié Salpêtrière, Sorbonne Université, 75013 Paris, France
| | - Ahmed S Abdelfattah
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virgina 20147, United States
- Department of Neuroscience, Brown University, Providence, Rhode Island 02906, United States
| | - Eric R Schreiter
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virgina 20147, United States
| | - M Joanne Lemieux
- Department of Biochemistry, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Jaime de Juan-Sanz
- Institut du Cerveau-Paris Brain Institute-ICM, Inserm, CNRS, APHP, Häpital de la Pitié Salpêtrière, Sorbonne Université, 75013 Paris, France
| | - David Perrais
- CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, Bordeaux 33076, France
| | - Robert E Campbell
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
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7
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Margiotta A. Role of SNAREs and Rabs in Myelin Regulation. Int J Mol Sci 2023; 24:ijms24119772. [PMID: 37298723 DOI: 10.3390/ijms24119772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 05/31/2023] [Accepted: 06/03/2023] [Indexed: 06/12/2023] Open
Abstract
The myelin sheath is an insulating layer around the nerves of the brain and spinal cord which allows a fast and efficient nerve conduction. Myelin is made of protein and fatty substances and gives protection for the propagation of the electrical impulse. The myelin sheath is formed by oligodendrocytes in the central nervous system (CNS) and by Schwann cells in the peripheral nervous system (PNS). The myelin sheath presents a highly organized structure and expands both radially and longitudinally, but in a different way and with a different composition. Myelin alterations determine the onset of several neuropathies, as the electrical signal can be slowed or stopped. Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and ras (rat sarcoma)-associated binding proteins (rabs) have been proved to contribute to several aspects regarding the formation of myelin or dysmyelination. Here, I will describe the role of these proteins in regulating membrane trafficking and nerve conduction, myelin biogenesis and maintenance.
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Affiliation(s)
- Azzurra Margiotta
- Department of Clinical Dentistry, Faculty of Medicine, University of Bergen, 5009 Bergen, Norway
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8
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Caenorhabditis elegans as a Model System to Study Human Neurodegenerative Disorders. Biomolecules 2023; 13:biom13030478. [PMID: 36979413 PMCID: PMC10046667 DOI: 10.3390/biom13030478] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 02/18/2023] [Accepted: 03/01/2023] [Indexed: 03/08/2023] Open
Abstract
In recent years, advances in science and technology have improved our quality of life, enabling us to tackle diseases and increase human life expectancy. However, longevity is accompanied by an accretion in the frequency of age-related neurodegenerative diseases, creating a growing burden, with pervasive social impact for human societies. The cost of managing such chronic disorders and the lack of effective treatments highlight the need to decipher their molecular and genetic underpinnings, in order to discover new therapeutic targets. In this effort, the nematode Caenorhabditis elegans serves as a powerful tool to recapitulate several disease-related phenotypes and provides a highly malleable genetic model that allows the implementation of multidisciplinary approaches, in addition to large-scale genetic and pharmacological screens. Its anatomical transparency allows the use of co-expressed fluorescent proteins to track the progress of neurodegeneration. Moreover, the functional conservation of neuronal processes, along with the high homology between nematode and human genomes, render C. elegans extremely suitable for the study of human neurodegenerative disorders. This review describes nematode models used to study neurodegeneration and underscores their contribution in the effort to dissect the molecular basis of human diseases and identify novel gene targets with therapeutic potential.
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Shi B, Wu XS, Cordero NP, Moreira SL, Wu LG. Light and electron microscopic imaging of synaptic vesicle endocytosis at mouse hippocampal cultures. STAR Protoc 2022; 3:101495. [PMID: 35776639 PMCID: PMC9249854 DOI: 10.1016/j.xpro.2022.101495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/29/2022] [Accepted: 06/06/2022] [Indexed: 11/05/2022] Open
Abstract
Following the release of neurotransmitters at synaptic vesicles via exocytosis, endocytosis is initiated to retrieve vesicles that have fused with the plasma membrane of nerve terminals and recycle them, thus sustaining synaptic transmission. Here, we describe imaging-based protocols for quantitative measurements of endocytosis at cultured synapses. These protocols include (1) primary culture of mouse hippocampal neurons, (2) studying endocytosis at neurons transfected with a pH-sensitive synaptophysin-pHluorin2× using fluorescent microscopy, and (3) imaging endocytosis at fixed neurons with electron microscopy. For complete details on the use and execution of this protocol, please refer to Wu et al. (2016) and Wu et al. (2021). Detailed protocol for primary culture and transfection of mouse hippocampal neurons Light microscopy and analysis of endocytosis in cultured neurons Electron microscopy and analysis of vesicle and endosome formation
Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.
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Abstract
Optogenetic actuators enable highly precise spatiotemporal interrogation of biological processes at levels ranging from the subcellular to cells, circuits and behaving organisms. Although their application in neuroscience has traditionally focused on the control of spiking activity at the somatodendritic level, the scope of optogenetic modulators for direct manipulation of presynaptic functions is growing. Presynaptically localized opsins combined with light stimulation at the terminals allow light-mediated neurotransmitter release, presynaptic inhibition, induction of synaptic plasticity and specific manipulation of individual components of the presynaptic machinery. Here, we describe presynaptic applications of optogenetic tools in the context of the unique cell biology of axonal terminals, discuss their potential shortcomings and outline future directions for this rapidly developing research area.
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11
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Park C, Jung S, Park H. Single vesicle tracking for studying synaptic vesicle dynamics in small central synapses. Curr Opin Neurobiol 2022; 76:102596. [PMID: 35803103 DOI: 10.1016/j.conb.2022.102596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/20/2022] [Accepted: 05/27/2022] [Indexed: 11/26/2022]
Abstract
Sustained neurotransmission is driven by a continuous supply of synaptic vesicles to the release sites and modulated by synaptic vesicle dynamics. However, synaptic vesicle dynamics in synapses remain elusive because of technical limitations. Recent advances in fluorescence imaging techniques have enabled the tracking of single synaptic vesicles in small central synapses in living neurons. Single vesicle tracking has uncovered a wealth of new information about synaptic vesicle dynamics both within and outside presynaptic terminals, showing that single vesicle tracking is an effective tool for studying synaptic vesicle dynamics. Particularly, single vesicle tracking with high spatiotemporal resolution has revealed the dependence of synaptic vesicle dynamics on the location, stages of recycling, and neuronal activity. This review summarizes the recent findings from single synaptic vesicle tracking in small central synapses and their implications in synaptic transmission and pathogenic mechanisms of neurodegenerative diseases.
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Affiliation(s)
- Chungwon Park
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077, Hong Kong
| | - Sangyong Jung
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A∗STAR), 11 Biopolis Way, 138667, Singapore; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 119077, Singapore
| | - Hyokeun Park
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077, Hong Kong; Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077, Hong Kong; State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077, Hong Kong.
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12
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Guo X, Han S, Wei L, Arpino G, Shin W, Wang X, Wu LG. Real-time visualization of exo- and endocytosis membrane dynamics with confocal and super-resolution microscopy. STAR Protoc 2022; 3:101404. [PMID: 35600934 PMCID: PMC9120246 DOI: 10.1016/j.xpro.2022.101404] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Real-time confocal and super-resolution imaging reveals membrane dynamics of exo- and endocytosis, including hemi-fusion, fusion pore opening, expansion, constriction, closure (kiss-and-run), fused-vesicle shrinking (shrink fusion), and flat membrane transition to vesicles via intermediate Λ- and Ω-shape structures. Here, we describe a protocol for imaging these membrane dynamics, including primary culture of bovine adrenal chromaffin cells, fluorescent probe application, patch-clamp to deliver depolarization and evoke exo- and endocytosis, electron microscopy (EM), and real-time confocal and stimulated emission depletion (STED) microscopy. For complete details on the use and execution of this protocol, please refer to Zhao et al. (2016), Shin et al. (2018), and Shin et al. (2021). Real-time visualization of membrane dynamics of vesicle fusion and endocytosis Confocal imaging, STED imaging, and electron microscopy of exo-endocytosis Fluorescent probes and procedures for labeling plasma membrane and vesicles Detailed protocol for culturing chromaffin cells from bovine adrenal gland
Publisher's note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.
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13
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Shi B, Jin YH, Wu LG. Dynamin 1 controls vesicle size and endocytosis at hippocampal synapses. Cell Calcium 2022; 103:102564. [PMID: 35220002 PMCID: PMC9009158 DOI: 10.1016/j.ceca.2022.102564] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/27/2022] [Accepted: 02/15/2022] [Indexed: 11/16/2022]
Abstract
Following calcium-triggered vesicle exocytosis, endocytosis regenerates vesicles to maintain exocytosis and thus synaptic transmission, which underlies neuronal circuit activities. Although most molecules involved in endocytosis have been identified, it remains rather poorly understood how endocytic machinery regulates vesicle size. Vesicle size, together with the transmitter concentration inside the vesicle, determines the amount of transmitter the vesicle can release, the quantal size, that may control the strength of synaptic transmission. Here, we report that, surprisingly, knockout of the GTPase dynamin 1, the most abundant brain dynamin isoform known to catalyze fission of the membrane pit's neck (the last step of endocytosis), not only significantly slowed endocytosis but also increased the synaptic vesicle diameter by as much as ∼40-64% at cultured hippocampal synapses. Furthermore, dynamin 1 knockout increased the size of membrane pits, the precursor for endocytic vesicle formation. These results suggest an important function of dynamin other than its well-known fission function - control of vesicle size at the pit formation stage.
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Affiliation(s)
- Bo Shi
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bethesda, MD 20892 United States; Biological Sciences Graduate Program, College of Computer, Mathematical, and Natural Sciences, University of Maryland, College Park, MD 20740 United States
| | - Ying-Hui Jin
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bethesda, MD 20892 United States; Department of Critical Care Medicine, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Ave, Guangzhou 510515, China
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bethesda, MD 20892 United States.
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14
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An SJ, Stagi M, Gould TJ, Wu Y, Mlodzianoski M, Rivera-Molina F, Toomre D, Strittmatter SM, De Camilli P, Bewersdorf J, Zenisek D. Multimodal imaging of synaptic vesicles with a single probe. CELL REPORTS METHODS 2022; 2:100199. [PMID: 35497490 PMCID: PMC9046237 DOI: 10.1016/j.crmeth.2022.100199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/11/2022] [Accepted: 03/28/2022] [Indexed: 05/17/2023]
Abstract
A complete understanding of synaptic-vesicle recycling requires the use of multiple microscopy methods to obtain complementary information. However, many currently available probes are limited to a specific microscopy modality, which necessitates the use of multiple probes and labeling paradigms. Given the complexity of vesicle populations and recycling pathways, having new single-vesicle probes that could be used for multiple microscopy techniques would complement existing sets of tools for studying vesicle function. Here, we present a probe based on the membrane-binding C2 domain of cytosolic phospholipase A2 (cPLA2) that fulfills this need. By conjugating the C2 domain with different detectable tags, we demonstrate that a single, modular probe can allow synaptic vesicles to be imaged at multiple levels of spatial and temporal resolution. Moreover, as a general endocytic marker, the C2 domain may also be used to study membrane recycling in many cell types.
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Affiliation(s)
- Seong J. An
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Massimiliano Stagi
- Program in Cellular Neuroscience, Neurodegeneration & Repair, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Molecular Physiology & Cell Signalling, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool 69 3BX, UK
| | - Travis J. Gould
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Physics and Astronomy, Bates College, Lewiston, ME 04240, USA
| | - Yumei Wu
- Program in Cellular Neuroscience, Neurodegeneration & Repair, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Michael Mlodzianoski
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Biomedical Engineering, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Felix Rivera-Molina
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Derek Toomre
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Stephen M. Strittmatter
- Program in Cellular Neuroscience, Neurodegeneration & Repair, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Pietro De Camilli
- Program in Cellular Neuroscience, Neurodegeneration & Repair, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Joerg Bewersdorf
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Biomedical Engineering, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
| | - David Zenisek
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Program in Cellular Neuroscience, Neurodegeneration & Repair, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
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15
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Wang X, Sun M, Chan CY, Wu LG. Phospholipase A 2-based probes to study vesicle trafficking. CELL REPORTS METHODS 2022; 2:100206. [PMID: 35497501 PMCID: PMC9046444 DOI: 10.1016/j.crmeth.2022.100206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Vesicle exo- and endocytosis mediate important biological functions, including synaptic transmission. In this issue of Cell Reports Methods, Seong J. An et al. found that the fluorescently tagged C2 domain of phospholipase A2 binds to membrane phosphatidylcholine and thus labels vesicle membrane, allowing for super-resolution and electron microscopic visualization of vesicle trafficking.
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Affiliation(s)
- Xin Wang
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Min Sun
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Chung Yu Chan
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
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16
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Liu GT, Kochlamazashvili G, Puchkov D, Müller R, Schultz C, Mackintosh AI, Vollweiter D, Haucke V, Soykan T. Endosomal phosphatidylinositol 3-phosphate controls synaptic vesicle cycling and neurotransmission. EMBO J 2022; 41:e109352. [PMID: 35318705 PMCID: PMC9058544 DOI: 10.15252/embj.2021109352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 02/24/2022] [Accepted: 03/01/2022] [Indexed: 11/09/2022] Open
Abstract
Neural circuit function requires mechanisms for controlling neurotransmitter release and the activity of neuronal networks, including modulation by synaptic contacts, synaptic plasticity, and homeostatic scaling. However, how neurons intrinsically monitor and feedback control presynaptic neurotransmitter release and synaptic vesicle (SV) recycling to restrict neuronal network activity remains poorly understood at the molecular level. Here, we investigated the reciprocal interplay between neuronal endosomes, organelles of central importance for the function of synapses, and synaptic activity. We show that elevated neuronal activity represses the synthesis of endosomal lipid phosphatidylinositol 3-phosphate [PI(3)P] by the lipid kinase VPS34. Neuronal activity in turn is regulated by endosomal PI(3)P, the depletion of which reduces neurotransmission as a consequence of perturbed SV endocytosis. We find that this mechanism involves Calpain 2-mediated hyperactivation of Cdk5 downstream of receptor- and activity-dependent calcium influx. Our results unravel an unexpected function for PI(3)P-containing neuronal endosomes in the control of presynaptic vesicle cycling and neurotransmission, which may explain the involvement of the PI(3)P-producing VPS34 kinase in neurological disease and neurodegeneration.
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Affiliation(s)
- Guan-Ting Liu
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | | | - Dmytro Puchkov
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Rainer Müller
- European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, Heidelberg, Germany
| | - Carsten Schultz
- European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, Heidelberg, Germany.,Department of Chemical Physiology & Biochemistry, Oregon Health & Science University (OHSU), Portland, OR, USA
| | - Albert I Mackintosh
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Dennis Vollweiter
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.,Faculty of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin, Germany.,NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Tolga Soykan
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
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17
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Wu LG, Chan CY. Multiple Roles of Actin in Exo- and Endocytosis. Front Synaptic Neurosci 2022; 14:841704. [PMID: 35308832 PMCID: PMC8931529 DOI: 10.3389/fnsyn.2022.841704] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/11/2022] [Indexed: 11/20/2022] Open
Abstract
Cytoskeletal filamentous actin (F-actin) has long been considered a molecule that may regulate exo- and endocytosis. However, its exact roles remained elusive. Recent studies shed new light on many crucial roles of F-actin in regulating exo- and endocytosis. Here, this progress is reviewed from studies of secretory cells, particularly neurons and endocrine cells. These studies reveal that F-actin is involved in mediating all kinetically distinguishable forms of endocytosis, including ultrafast, fast, slow, bulk, and overshoot endocytosis, likely via membrane pit formation. F-actin promotes vesicle replenishment to the readily releasable pool most likely via active zone clearance, which may sustain synaptic transmission and overcome short-term depression of synaptic transmission during repetitive firing. By enhancing plasma membrane tension, F-actin promotes fusion pore expansion, vesicular content release, and a fusion mode called shrink fusion involving fusing vesicle shrinking. Not only F-actin, but also the F-actin assembly pathway, including ATP hydrolysis, N-WASH, and formin, are involved in mediating these roles of exo- and endocytosis. Neurological disorders, including spinocerebellar ataxia 13 caused by Kv3.3 channel mutation, may involve impairment of F-actin and its assembly pathway, leading in turn to impairment of exo- and endocytosis at synapses that may contribute to neurological disorders.
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18
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Clayton EL, Bonnycastle K, Isaacs AM, Cousin MA, Schorge S. A novel synaptopathy-defective synaptic vesicle protein trafficking in the mutant CHMP2B mouse model of frontotemporal dementia. J Neurochem 2022; 160:412-425. [PMID: 34855215 DOI: 10.1111/jnc.15551] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 11/10/2021] [Accepted: 11/18/2021] [Indexed: 12/13/2022]
Abstract
Mutations in the ESCRT-III subunit CHMP2B cause frontotemporal dementia (FTD) and lead to impaired endolysosomal trafficking and lysosomal storage pathology in neurons. We investigated the effect of mutant CHMP2B on synaptic pathology, as ESCRT function was recently implicated in the degradation of synaptic vesicle (SV) proteins. We report here that expression of C-terminally truncated mutant CHMP2B results in a novel synaptopathy. This unique synaptic pathology is characterised by selective retention of presynaptic SV trafficking proteins in aged mutant CHMP2B transgenic mice, despite significant loss of postsynaptic proteins. Furthermore, ultrastructural analysis of primary cortical cultures from transgenic CHMP2B mice revealed a significant increase in the number of presynaptic endosomes, while neurons expressing mutant CHMP2B display defective SV recycling and alterations to functional SV pools. Therefore, we reveal how mutations in CHMP2B affect specific presynaptic proteins and SV recycling, identifying CHMP2B FTD as a novel synaptopathy. This novel synaptopathic mechanism of impaired SV physiology may be a key early event in multiple forms of FTD, since proteins that mediate the most common genetic forms of FTD all localise at the presynapse.
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Affiliation(s)
- Emma L Clayton
- Department of Pharmacology, UCL School of Pharmacy, London, UK
- Currently at UK Dementia Research Institute at King's College London, London, UK
| | - Katherine Bonnycastle
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, Scotland
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, Scotland
| | - Adrian M Isaacs
- UK Dementia Research Institute at UCL, London, UK
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, Scotland
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, Scotland
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19
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Imbrosci B, Schmitz D, Orlando M. Automated Detection and Localization of Synaptic Vesicles in Electron Microscopy Images. eNeuro 2022; 9:ENEURO.0400-20.2021. [PMID: 34983830 PMCID: PMC8805189 DOI: 10.1523/eneuro.0400-20.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 11/04/2021] [Accepted: 11/23/2021] [Indexed: 11/21/2022] Open
Abstract
Information transfer and integration in the brain occurs at chemical synapses and is mediated by the fusion of synaptic vesicles filled with neurotransmitter. Synaptic vesicle dynamic spatial organization regulates synaptic transmission as well as synaptic plasticity. Because of their small size, synaptic vesicles require electron microscopy (EM) for their imaging, and their analysis is conducted manually. The manual annotation and segmentation of the hundreds to thousands of synaptic vesicles, is highly time consuming and limits the throughput of data collection. To overcome this limitation, we built an algorithm, mainly relying on convolutional neural networks (CNNs), capable of automatically detecting and localizing synaptic vesicles in electron micrographs. The algorithm was trained on murine synapses but we show that it works well on synapses from different species, ranging from zebrafish to human, and from different preparations. As output, we provide the vesicle count and coordinates, the nearest neighbor distance (nnd) and the estimate of the vesicles area. We also provide a graphical user interface (GUI) to guide users through image analysis, result visualization, and manual proof-reading. The application of our algorithm is especially recommended for images produced by transmission EM. Since this type of imaging is used routinely to investigate presynaptic terminals, our solution will likely be of interest for numerous research groups.
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Affiliation(s)
- Barbara Imbrosci
- German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin 10117, Germany
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin 10117, Germany
| | - Dietmar Schmitz
- German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin 10117, Germany
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin 10117, Germany
- NeuroCure Cluster of Excellence, Berlin 10117, Germany
- Bernstein Center for Computational Neuroscience (BCCN) Berlin, Berlin 10115, Germany
- Einstein Center for Neurosciences (ECN) Berlin, Berlin 10117, Germany
- Max-Delbrück-Centrum (MDC) for Molecular Medicine, Berlin 13125, Germany
| | - Marta Orlando
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin 10117, Germany
- NeuroCure Cluster of Excellence, Berlin 10117, Germany
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20
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Schmied C, Soykan T, Bolz S, Haucke V, Lehmann M. SynActJ: Easy-to-Use Automated Analysis of Synaptic Activity. FRONTIERS IN COMPUTER SCIENCE 2021. [DOI: 10.3389/fcomp.2021.777837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Neuronal synapses are highly dynamic communication hubs that mediate chemical neurotransmission via the exocytic fusion and subsequent endocytic recycling of neurotransmitter-containing synaptic vesicles (SVs). Functional imaging tools allow for the direct visualization of synaptic activity by detecting action potentials, pre- or postsynaptic calcium influx, SV exo- and endocytosis, and glutamate release. Fluorescent organic dyes or synapse-targeted genetic molecular reporters, such as calcium, voltage or neurotransmitter sensors and synapto-pHluorins reveal synaptic activity by undergoing rapid changes in their fluorescence intensity upon neuronal activity on timescales of milliseconds to seconds, which typically are recorded by fast and sensitive widefield live cell microscopy. The analysis of the resulting time-lapse movies in the past has been performed by either manually picking individual structures, custom scripts that have not been made widely available to the scientific community, or advanced software toolboxes that are complicated to use. For the precise, unbiased and reproducible measurement of synaptic activity, it is key that the research community has access to bio-image analysis tools that are easy-to-apply and allow the automated detection of fluorescent intensity changes in active synapses. Here we present SynActJ (Synaptic Activity in ImageJ), an easy-to-use fully open-source workflow that enables automated image and data analysis of synaptic activity. The workflow consists of a Fiji plugin performing the automated image analysis of active synapses in time-lapse movies via an interactive seeded watershed segmentation that can be easily adjusted and applied to a dataset in batch mode. The extracted intensity traces of each synaptic bouton are automatically processed, analyzed, and plotted using an R Shiny workflow. We validate the workflow on time-lapse images of stimulated synapses expressing the SV exo-/endocytosis reporter Synaptophysin-pHluorin or a synapse-targeted calcium sensor, Synaptophysin-RGECO. We compare the automatic workflow to manual analysis and compute calcium-influx and SV exo-/endocytosis kinetics and other parameters for synaptic vesicle recycling under different conditions. We predict SynActJ to become an important tool for the analysis of synaptic activity and synapse properties.
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21
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Dagar S, Teng Z, Gottmann K. Transsynaptic N-Cadherin Adhesion Complexes Control Presynaptic Vesicle and Bulk Endocytosis at Physiological Temperature. Front Cell Neurosci 2021; 15:713693. [PMID: 34759800 PMCID: PMC8573734 DOI: 10.3389/fncel.2021.713693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 09/13/2021] [Indexed: 11/30/2022] Open
Abstract
At mammalian glutamatergic synapses, most basic elements of synaptic transmission have been shown to be modulated by specific transsynaptic adhesion complexes. However, although crucial for synapse homeostasis, a physiological regulation of synaptic vesicle endocytosis by adhesion molecules has not been firmly established. The homophilic adhesion protein N-cadherin is localized at the peri-active zone, where the highly temperature-dependent endocytosis of vesicles occurs. Here, we demonstrate an important modulatory role of N-cadherin in endocytosis at near physiological temperature by synaptophysin-pHluorin imaging. Different modes of endocytosis including bulk endocytosis were dependent on N-cadherin expression and function. N-cadherin modulation might be mediated by actin filaments because actin polymerization ameliorated the knockout-induced endocytosis defect. Using super-resolution imaging, we found strong recruitment of N-cadherin to glutamatergic synapses upon massive vesicle release, which might in turn enhance vesicle endocytosis. This provides a novel, adhesion protein-mediated mechanism for efficient coupling of exo- and endocytosis.
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Affiliation(s)
- Sushma Dagar
- Institute of Neuro- and Sensory Physiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Zenghui Teng
- Institute of Neuro- and Sensory Physiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Kurt Gottmann
- Institute of Neuro- and Sensory Physiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
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22
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Chanaday NL, Kavalali ET. Synaptobrevin-2 dependent regulation of single synaptic vesicle endocytosis. Mol Biol Cell 2021; 32:1818-1823. [PMID: 34191540 PMCID: PMC8684713 DOI: 10.1091/mbc.e21-04-0213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/10/2021] [Accepted: 06/25/2021] [Indexed: 11/29/2022] Open
Abstract
Evidence from multiple systems indicates that vesicle SNARE (soluble NSF attachment receptor) proteins are involved in synaptic vesicle endocytosis, although their exact action at the level of single vesicles is unknown. Here we interrogate the role of the main synaptic vesicle SNARE mediating fusion, synaptobrevin-2 (also called VAMP2), in modulation of single synaptic vesicle retrieval. We report that in the absence of synaptobrevin-2, fast and slow modes of single synaptic vesicle retrieval are impaired, indicating a role of the SNARE machinery in coupling exocytosis to endocytosis of single synaptic vesicles. Ultrafast endocytosis was impervious to changes in the levels of synaptobrevin-2, pointing to a separate molecular mechanism underlying this type of recycling. Taken together with earlier studies suggesting a role of synaptobrevin-2 in endocytosis, these results indicate that the machinery for fast synchronous release couples fusion to retrieval and regulates the kinetics of endocytosis in a Ca2+-dependent manner.
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Affiliation(s)
- Natali L. Chanaday
- Department of Pharmacology, School of Medicine, Vanderbilt University, Nashville, TN 37240-7933
| | - Ege T. Kavalali
- Department of Pharmacology, School of Medicine, Vanderbilt University, Nashville, TN 37240-7933
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37240-7933
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23
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Taylor HBC, Emptage NJ, Jeans AF. Long-term depression links amyloid-β to the pathological hyperphosphorylation of tau. Cell Rep 2021; 36:109638. [PMID: 34469725 PMCID: PMC8424646 DOI: 10.1016/j.celrep.2021.109638] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 06/18/2021] [Accepted: 08/09/2021] [Indexed: 11/28/2022] Open
Abstract
In Alzheimer's disease, soluble oligomers of the amyloid-β peptide (Aβo) trigger a cascade of events that includes abnormal hyperphosphorylation of the protein tau, which is essential for pathogenesis. However, the mechanistic link between these two key pathological proteins remains unclear. Using hippocampal slices, we show here that an Aβo-mediated increase in glutamate release probability causes enhancement of synaptically evoked N-methyl-d-aspartate subtype glutamate receptor (NMDAR)-dependent long-term depression (LTD). We also find that elevated glutamate release probability is required for Aβo-induced pathological hyperphosphorylation of tau, which is likewise NMDAR dependent. Finally, we show that chronic, repeated chemical or optogenetic induction of NMDAR-dependent LTD alone is sufficient to cause tau hyperphosphorylation without Aβo. Together, these results support a possible causal chain in which Aβo increases glutamate release probability, thus leading to enhanced LTD induction, which in turn drives hyperphosphorylation of tau. Our data identify a mechanistic pathway linking the two critical pathogenic proteins of AD.
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Affiliation(s)
- Henry B C Taylor
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Nigel J Emptage
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Alexander F Jeans
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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24
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Subrahmanyam R, Dwivedi D, Rashid Z, Bonnycastle K, Cousin MA, Chattarji S. Reciprocal regulation of spontaneous synaptic vesicle fusion by Fragile X mental retardation protein and group I metabotropic glutamate receptors. J Neurochem 2021; 158:1094-1109. [PMID: 34327719 DOI: 10.1111/jnc.15484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 06/21/2021] [Accepted: 07/22/2021] [Indexed: 11/29/2022]
Abstract
Fragile X mental retardation protein (FMRP) is a neuronal protein mediating multiple functions, with its absence resulting in one of the most common monogenic causes of autism, Fragile X syndrome (FXS). Analyses of FXS pathophysiology have identified a range of aberrations in synaptic signaling pathways and plasticity associated with group I metabotropic glutamate (mGlu) receptors. These studies, however, have mostly focused on the post-synaptic functions of FMRP and mGlu receptor activation, and relatively little is known about their presynaptic effects. Neurotransmitter release is mediated via multiple forms of synaptic vesicle (SV) fusion, each of which contributes to specific neuronal functions. The impacts of mGlu receptor activation and loss of FMRP on these SV fusion events remain unexplored. Here we combined electrophysiological and fluorescence imaging analyses on primary hippocampal cultures prepared from an Fmr1 knockout (KO) rat model. Compared to wild-type (WT) hippocampal neurons, KO neurons displayed an increase in the frequency of spontaneous excitatory post-synaptic currents (sEPSCs), as well as spontaneous SV fusion events. Pharmacological activation of mGlu receptors in WT neurons caused a similar increase in spontaneous SV fusion and sEPSC frequency. Notably, this increase in SV fusion was not observed when spontaneous activity was blocked using the sodium channel antagonist tetrodotoxin. Importantly, the effect of mGlu receptor activation on spontaneous SV fusion was occluded in Fmr1 KO neurons. Together, our results reveal that FMRP represses spontaneous presynaptic SV fusion, whereas mGlu receptor activation increases this event. This reciprocal control appears to be mediated via their regulation of intrinsic neuronal excitability.
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Affiliation(s)
- Rohini Subrahmanyam
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India
| | - Deepanjali Dwivedi
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India
| | - Zubin Rashid
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India
| | - Katherine Bonnycastle
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK.,The Patrick Wild Centre, University of Edinburgh, Edinburgh, UK.,Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Michael A Cousin
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK.,The Patrick Wild Centre, University of Edinburgh, Edinburgh, UK.,Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Sumantra Chattarji
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India.,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK.,The Patrick Wild Centre, University of Edinburgh, Edinburgh, UK.,Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Centre for Brain Development and Repair, Institute for Stem Cell Biology and Regenerative Medicine, Bengaluru, India
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25
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Ivanova D, Dobson KL, Gajbhiye A, Davenport EC, Hacker D, Ultanir SK, Trost M, Cousin MA. Control of synaptic vesicle release probability via VAMP4 targeting to endolysosomes. SCIENCE ADVANCES 2021; 7:7/18/eabf3873. [PMID: 33931449 PMCID: PMC8087399 DOI: 10.1126/sciadv.abf3873] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 03/11/2021] [Indexed: 05/03/2023]
Abstract
Synaptic vesicle (SV) release probability (Pr), determines the steady state and plastic control of neurotransmitter release. However, how diversity in SV composition arises and regulates the Pr of individual SVs is not understood. We found that modulation of the copy number of the noncanonical vesicular SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor), vesicle-associated membrane protein 4 (VAMP4), on SVs is key for regulating Pr. Mechanistically, this is underpinned by its reduced ability to form an efficient SNARE complex with canonical plasma membrane SNAREs. VAMP4 has unusually high synaptic turnover and is selectively sorted to endolysosomes during activity-dependent bulk endocytosis. Disruption of endolysosomal trafficking and function markedly increased the abundance of VAMP4 in the SV pool and inhibited SV fusion. Together, our results unravel a new mechanism for generating SV heterogeneity and control of Pr through coupling of SV recycling to a major clearing system that regulates protein homeostasis.
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Affiliation(s)
- Daniela Ivanova
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland.
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
| | - Katharine L Dobson
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
| | - Akshada Gajbhiye
- Newcastle University Biosciences Institute, Faculty of Medical Sciences, Newcastle upon Tyne NE2 4HH, UK
| | - Elizabeth C Davenport
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
| | - Daniela Hacker
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
| | - Sila K Ultanir
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Matthias Trost
- Newcastle University Biosciences Institute, Faculty of Medical Sciences, Newcastle upon Tyne NE2 4HH, UK
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland.
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
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26
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Methods of measuring presynaptic function with fluorescence probes. Appl Microsc 2021; 51:2. [PMID: 33730244 PMCID: PMC7969681 DOI: 10.1186/s42649-021-00051-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 03/09/2021] [Indexed: 01/02/2023] Open
Abstract
Synaptic vesicles, which are endogenous to neurotransmitters, are involved in exocytosis by active potentials and release neurotransmitters. Synaptic vesicles used in neurotransmitter release are reused via endocytosis to maintain a pool of synaptic vesicles. Synaptic vesicles show different types of exo- and endocytosis depending on animal species, type of nerve cell, and electrical activity. To accurately understand the dynamics of synaptic vesicles, direct observation of synaptic vesicles is required; however, it was difficult to observe synaptic vesicles of size 40-50 nm in living neurons. The exo-and endocytosis of synaptic vesicles was confirmed by labeling the vesicles with a fluorescent agent and measuring the changes in fluorescence intensity. To date, various methods of labeling synaptic vesicles have been proposed, and each method has its own characteristics, strength, and drawbacks. In this study, we introduce methods that can measure presynaptic activity and describe the characteristics of each technique.
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27
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Liu A, Huang X, He W, Xue F, Yang Y, Liu J, Chen L, Yuan L, Xu P. pHmScarlet is a pH-sensitive red fluorescent protein to monitor exocytosis docking and fusion steps. Nat Commun 2021; 12:1413. [PMID: 33658493 PMCID: PMC7930027 DOI: 10.1038/s41467-021-21666-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 02/05/2021] [Indexed: 12/21/2022] Open
Abstract
pH-sensitive fluorescent proteins (FPs) are highly advantageous for the non-invasive monitoring of exocytosis events. Superecliptic pHluorin (SEP), a green pH-sensitive FP, has been widely used for imaging single-vesicle exocytosis. However, the docking step cannot be visualized using this FP, since the fluorescence signal inside vesicles is too low to be observed during docking process. Among the available red pH-sensitive FPs, none is comparable to SEP for practical applications due to unoptimized pH-sensitivity and fluorescence brightness or severe photochromic behavior. In this study, we engineer a bright and photostable red pH-sensitive FP, named pHmScarlet, which compared to other red FPs has higher pH sensitivity and enables the simultaneous detection of vesicle docking and fusion. pHmScarlet can also be combined with SEP for dual-color imaging of two individual secretory events. Furthermore, although the emission wavelength of pHmScarlet is red-shifted compared to that of SEP, its spatial resolution is high enough to show the ring structure of vesicle fusion pores using Hessian structured illumination microscopy (Hessian-SIM).
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Affiliation(s)
- Anyuan Liu
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Xiaoshuai Huang
- Biomedical Engineering Department, Peking University, Beijing, China
| | - Wenting He
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Fudong Xue
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yanrui Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Science, Beijing, China
| | - Jiajia Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Science, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Liangyi Chen
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Lin Yuan
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
| | - Pingyong Xu
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
- Department of Clinical Laboratory, Children's Hospital of Chongqing Medical University, Chongqing, China.
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28
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Du M, Di ZW, Gürsoy D, Xian RP, Kozorovitskiy Y, Jacobsen C. Upscaling X-ray nanoimaging to macroscopic specimens. J Appl Crystallogr 2021; 54:386-401. [PMID: 33953650 PMCID: PMC8056767 DOI: 10.1107/s1600576721000194] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 01/06/2021] [Indexed: 11/10/2022] Open
Abstract
Upscaling X-ray nanoimaging to macroscopic specimens has the potential for providing insights across multiple length scales, but its feasibility has long been an open question. By combining the imaging requirements and existing proof-of-principle examples in large-specimen preparation, data acquisition and reconstruction algorithms, the authors provide imaging time estimates for howX-ray nanoimaging can be scaled to macroscopic specimens. To arrive at this estimate, a phase contrast imaging model that includes plural scattering effects is used to calculate the required exposure and corresponding radiation dose. The coherent X-ray flux anticipated from upcoming diffraction-limited light sources is then considered. This imaging time estimation is in particular applied to the case of the connectomes of whole mouse brains. To image the connectome of the whole mouse brain, electron microscopy connectomics might require years, whereas optimized X-ray microscopy connectomics could reduce this to one week. Furthermore, this analysis points to challenges that need to be overcome (such as increased X-ray detector frame rate) and opportunities that advances in artificial-intelligence-based 'smart' scanning might provide. While the technical advances required are daunting, it is shown that X-ray microscopy is indeed potentially applicable to nanoimaging of millimetre- or even centimetre-size specimens.
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Affiliation(s)
- Ming Du
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Zichao Wendy Di
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.,Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Doǧa Gürsoy
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.,Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, IL 60208, USA
| | - R Patrick Xian
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
| | - Yevgenia Kozorovitskiy
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA.,Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208, USA
| | - Chris Jacobsen
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.,Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208, USA.,Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
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29
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Song XL, Liu DS, Qiang M, Li Q, Liu MG, Li WG, Qi X, Xu NJ, Yang G, Zhu MX, Xu TL. Postsynaptic Targeting and Mobility of Membrane Surface-Localized hASIC1a. Neurosci Bull 2021; 37:145-165. [PMID: 32996060 PMCID: PMC7870742 DOI: 10.1007/s12264-020-00581-9] [Citation(s) in RCA: 3] [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: 02/28/2020] [Accepted: 05/14/2020] [Indexed: 01/19/2023] Open
Abstract
Acid-sensing ion channels (ASICs), the main H+ receptors in the central nervous system, sense extracellular pH fluctuations and mediate cation influx. ASIC1a, the major subunit responsible for acid-activated current, is widely expressed in brain neurons, where it plays pivotal roles in diverse functions including synaptic transmission and plasticity. However, the underlying molecular mechanisms for these functions remain mysterious. Using extracellular epitope tagging and a novel antibody recognizing the hASIC1a ectodomain, we examined the membrane targeting and dynamic trafficking of hASIC1a in cultured cortical neurons. Surface hASIC1a was distributed throughout somata and dendrites, clustered in spine heads, and co-localized with postsynaptic markers. By extracellular pHluorin tagging and fluorescence recovery after photobleaching, we detected movement of hASIC1a in synaptic spine heads. Single-particle tracking along with use of the anti-hASIC1a ectodomain antibody revealed long-distance migration and local movement of surface hASIC1a puncta on dendrites. Importantly, enhancing synaptic activity with brain-derived neurotrophic factor accelerated the trafficking and lateral mobility of hASIC1a. With this newly-developed toolbox, our data demonstrate the synaptic location and high dynamics of functionally-relevant hASIC1a on the surface of excitatory synapses, supporting its involvement in synaptic functions.
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Affiliation(s)
- Xing-Lei Song
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Di-Shi Liu
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Min Qiang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, 201210, China
| | - Qian Li
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai, 201210, China
| | - Ming-Gang Liu
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai, 201210, China
| | - Wei-Guang Li
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai, 201210, China
| | - Xin Qi
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Nan-Jie Xu
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai, 201210, China
| | - Guang Yang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, 201210, China
| | - Michael Xi Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA.
| | - Tian-Le Xu
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China.
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
- Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai, 201210, China.
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30
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Cousin MA, Smillie KJ. Monitoring Activity-Dependent Bulk Endocytosis in Primary Neuronal Culture Using Large Fluorescent Dextrans. Methods Mol Biol 2021; 2233:101-111. [PMID: 33222130 DOI: 10.1007/978-1-0716-1044-2_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The efficient recycling of synaptic vesicles (SVs) during neuronal activity is central for sustaining brain function. During intense neuronal activity, the dominant mechanism of SV retrieval is activity-dependent bulk endocytosis (ADBE). Here, we describe a method to monitor ADBE in isolation from other SV endocytosis modes, via the uptake of large fluorescent fluid-phase markers in primary neuronal culture. Furthermore, we outline how to monitor ADBE using this approach across a field of neurons or in individual neurons.
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Affiliation(s)
- Michael A Cousin
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh, Scotland, UK
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh, Scotland, UK
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh, Scotland, UK
| | - Karen J Smillie
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh, Scotland, UK.
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh, Scotland, UK.
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31
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Neuronal Autophagy Regulates Presynaptic Neurotransmission by Controlling the Axonal Endoplasmic Reticulum. Neuron 2020; 109:299-313.e9. [PMID: 33157003 PMCID: PMC7837115 DOI: 10.1016/j.neuron.2020.10.005] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 08/22/2020] [Accepted: 10/05/2020] [Indexed: 12/21/2022]
Abstract
Neurons are known to rely on autophagy for removal of defective proteins or organelles to maintain synaptic neurotransmission and counteract neurodegeneration. In spite of its importance for neuronal health, the physiological substrates of neuronal autophagy in the absence of proteotoxic challenge have remained largely elusive. We use knockout mice conditionally lacking the essential autophagy protein ATG5 and quantitative proteomics to demonstrate that loss of neuronal autophagy causes selective accumulation of tubular endoplasmic reticulum (ER) in axons, resulting in increased excitatory neurotransmission and compromised postnatal viability in vivo. The gain in excitatory neurotransmission is shown to be a consequence of elevated calcium release from ER stores via ryanodine receptors accumulated in axons and at presynaptic sites. We propose a model where neuronal autophagy controls axonal ER calcium stores to regulate neurotransmission in healthy neurons and in the brain. Neuronal autophagy controls the endoplasmic reticulum (ER) in axons Loss of neuronal autophagy leads to increased excitatory neurotransmission Increased neurotransmission is due to elevated calcium release from ER stores
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32
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Taylor HBC, Tong R, Jeans AF, Emptage NJ. A Novel Optical Quantal Analysis of Miniature Events Reveals Enhanced Frequency Following Amyloid β Exposure. Front Cell Neurosci 2020; 14:564081. [PMID: 33240043 PMCID: PMC7669988 DOI: 10.3389/fncel.2020.564081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 10/01/2020] [Indexed: 11/17/2022] Open
Abstract
Non-evoked miniature release of neurotransmitters is increasingly recognized as playing an important role in neural function and is implicated in synaptic plasticity, metaplasticity, and homeostasis. Spontaneous miniature release events (minis) are usually measured electrophysiologically by recording the miniature postsynaptic currents (mEPSCs) that they evoke. However, this indirect technique can be confounded by changes within the postsynaptic neuron. Here, using the fluorescent probe SynaptopHluorin 2×, we have developed an optical method for the measurement of minis that enables direct assessment of release events. We use the technique to reveal that the frequency of minis following incubation of hippocampal neurons with Amyloid β oligomers (Aβo) is increased. Electrophysiological mEPSC recordings obtained under the same conditions report a decrease in frequency, with the discrepancy likely due to Aβo-induced changes in quantal size. Optical quantal analysis of minis may therefore have a role in the study of minis in both normal physiology and disease, as it can circumvent potential confounds caused by postsynaptic changes.
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Affiliation(s)
- Henry B. C. Taylor
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, United Kingdom
| | - Rudi Tong
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, United Kingdom
- Montreal Neurological Institute and Hospital, Montreal, QC, Canada
| | - Alexander F. Jeans
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, United Kingdom
| | - Nigel J. Emptage
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, United Kingdom
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33
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Gobbo F, Cattaneo A. Neuronal Activity at Synapse Resolution: Reporters and Effectors for Synaptic Neuroscience. Front Mol Neurosci 2020; 13:572312. [PMID: 33192296 PMCID: PMC7609880 DOI: 10.3389/fnmol.2020.572312] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 08/31/2020] [Indexed: 12/15/2022] Open
Abstract
The development of methods for the activity-dependent tagging of neurons enabled a new way to tackle the problem of engram identification at the cellular level, giving rise to groundbreaking findings in the field of memory studies. However, the resolution of activity-dependent tagging remains limited to the whole-cell level. Notably, events taking place at the synapse level play a critical role in the establishment of new memories, and strong experimental evidence shows that learning and synaptic plasticity are tightly linked. Here, we provide a comprehensive review of the currently available techniques that enable to identify and track the neuronal activity with synaptic spatial resolution. We also present recent technologies that allow to selectively interfere with specific subsets of synapses. Lastly, we discuss how these technologies can be applied to the study of learning and memory.
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Affiliation(s)
- Francesco Gobbo
- Bio@SNS Laboratory of Biology, Scuola Normale Superiore, Pisa, Italy
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Antonino Cattaneo
- Bio@SNS Laboratory of Biology, Scuola Normale Superiore, Pisa, Italy
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34
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Chenouard N, Xuan F, Tsien RW. Synaptic vesicle traffic is supported by transient actin filaments and regulated by PKA and NO. Nat Commun 2020; 11:5318. [PMID: 33087709 PMCID: PMC7578807 DOI: 10.1038/s41467-020-19120-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 09/25/2020] [Indexed: 11/10/2022] Open
Abstract
Synaptic vesicles (SVs) can be pooled across multiple synapses, prompting questions about their dynamic allocation for neurotransmission and plasticity. We find that the axonal traffic of recycling vesicles is not supported by ubiquitous microtubule-based motility but relies on actin instead. Vesicles freed from synaptic clusters undergo ~1 µm bouts of active transport, initiated by nearby elongation of actin filaments. Long distance translocation arises when successive bouts of active transport were linked by periods of free diffusion. The availability of SVs for active transport can be promptly increased by protein kinase A, a key player in neuromodulation. Vesicle motion is in turn impeded by shutting off axonal actin polymerization, mediated by nitric oxide-cyclic GMP signaling leading to inhibition of RhoA. These findings provide a potential framework for coordinating post-and pre-synaptic strength, using retrograde regulation of axonal actin dynamics to mobilize and recruit presynaptic SV resources.
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Affiliation(s)
- Nicolas Chenouard
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY, 10016, USA.,Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, F-33000, Bordeaux, France
| | - Feng Xuan
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY, 10016, USA.,Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, 60208, USA
| | - Richard W Tsien
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY, 10016, USA. .,Center for Neural Science, New York University, New York, NY, 10003, USA.
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35
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Rabut C, Yoo S, Hurt RC, Jin Z, Li H, Guo H, Ling B, Shapiro MG. Ultrasound Technologies for Imaging and Modulating Neural Activity. Neuron 2020; 108:93-110. [PMID: 33058769 PMCID: PMC7577369 DOI: 10.1016/j.neuron.2020.09.003] [Citation(s) in RCA: 104] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 08/25/2020] [Accepted: 09/01/2020] [Indexed: 02/06/2023]
Abstract
Visualizing and perturbing neural activity on a brain-wide scale in model animals and humans is a major goal of neuroscience technology development. Established electrical and optical techniques typically break down at this scale due to inherent physical limitations. In contrast, ultrasound readily permeates the brain, and in some cases the skull, and interacts with tissue with a fundamental resolution on the order of 100 μm and 1 ms. This basic ability has motivated major efforts to harness ultrasound as a modality for large-scale brain imaging and modulation. These efforts have resulted in already-useful neuroscience tools, including high-resolution hemodynamic functional imaging, focused ultrasound neuromodulation, and local drug delivery. Furthermore, recent breakthroughs promise to connect ultrasound to neurons at the genetic level for biomolecular imaging and sonogenetic control. In this article, we review the state of the art and ongoing developments in ultrasonic neurotechnology, building from fundamental principles to current utility, open questions, and future potential.
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Affiliation(s)
- Claire Rabut
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Sangjin Yoo
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Robert C Hurt
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Zhiyang Jin
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA, USA
| | - Hongyi Li
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Hongsun Guo
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Bill Ling
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Mikhail G Shapiro
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA.
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Sposini S, Rosendale M, Claverie L, Van TNN, Jullié D, Perrais D. Imaging endocytic vesicle formation at high spatial and temporal resolutions with the pulsed-pH protocol. Nat Protoc 2020; 15:3088-3104. [PMID: 32807908 DOI: 10.1038/s41596-020-0371-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 06/04/2020] [Indexed: 11/09/2022]
Abstract
Endocytosis is a fundamental process occurring in all eukaryotic cells. Live cell imaging of endocytosis has helped to decipher many of its mechanisms and regulations. With the pulsed-pH (ppH) protocol, one can detect the formation of individual endocytic vesicles (EVs) with an unmatched temporal resolution of 2 s. The ppH protocol makes use of cargo protein (e.g., the transferrin receptor) coupled to a pH-sensitive fluorescent protein, such as superecliptic pHluorin (SEP), which is brightly fluorescent at pH 7.4 but not fluorescent at pH <6.0. If the SEP moiety is at the surface, its fluorescence will decrease when cells are exposed to a low pH (5.5) buffer. If the SEP moiety has been internalized, SEP will remain fluorescent even during application of the low pH buffer. Fast perfusion enables the complete exchange of low and high pH extracellular solutions every 2 s, defining the temporal resolution of the technique. Unlike other imaging-based endocytosis assays, the ppH protocol detects EVs without a priori hypotheses on the dynamics of vesicle formation. Here, we explain how the ppH protocol quantifies the endocytic activity of living cells and the recruitment of associated proteins in real time. We provide a step-by-step procedure for expression of the reporter proteins with transient transfection, live cell image acquisition with synchronized pH changes and automated analysis. The whole protocol can be performed in 2 d to provide quantitative information on the endocytic process being studied.
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Affiliation(s)
- Silvia Sposini
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France.,CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France
| | - Morgane Rosendale
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France.,CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France.,CNRS, Institut des Sciences Moléculaires, UMR 5255, Talence, France
| | - Léa Claverie
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France.,CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France.,Euroquality, Bordeaux, France
| | - Thi Nhu Ngoc Van
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France.,CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France.,Sys2diag, Montpellier, France
| | - Damien Jullié
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France.,CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France.,University of California, San Francisco, San Francisco, CA, USA
| | - David Perrais
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France. .,CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France.
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Loss of huntingtin function slows synaptic vesicle endocytosis in striatal neurons from the httQ140/Q140 mouse model of Huntington's disease. Neurobiol Dis 2020; 134:104637. [DOI: 10.1016/j.nbd.2019.104637] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 08/23/2019] [Accepted: 10/09/2019] [Indexed: 12/13/2022] Open
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Kokotos AC, Harper CB, Marland JRK, Smillie KJ, Cousin MA, Gordon SL. Synaptophysin sustains presynaptic performance by preserving vesicular synaptobrevin-II levels. J Neurochem 2019; 151:28-37. [PMID: 31216055 PMCID: PMC6851701 DOI: 10.1111/jnc.14797] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 05/24/2019] [Accepted: 06/01/2019] [Indexed: 01/01/2023]
Abstract
The two most abundant molecules on synaptic vesicles (SVs) are synaptophysin and synaptobrevin‐II (sybII). SybII is essential for SV fusion, whereas synaptophysin is proposed to control the trafficking of sybII after SV fusion and its retrieval during endocytosis. Despite controlling key aspects of sybII packaging into SVs, the absence of synaptophysin results in negligible effects on neurotransmission. We hypothesised that this apparent absence of effect may be because of the abundance of sybII on SVs, with the impact of inefficient sybII retrieval only revealed during periods of repeated SV turnover. To test this hypothesis, we subjected primary cultures of synaptophysin knockout neurons to repeated trains of neuronal activity, while monitoring SV fusion events and levels of vesicular sybII. We identified a significant decrease in both the number of SV fusion events (monitored using the genetically encoded reporter vesicular glutamate transporter‐pHluorin) and vesicular sybII levels (via both immunofluorescence and Western blotting) using this protocol. This revealed that synaptophysin is essential to sustain both parameters during periods of repetitive SV turnover. This was confirmed by the rescue of presynaptic performance by the expression of exogenous synaptophysin. Importantly, the expression of exogenous sybII also fully restored SV fusion events in synaptophysin knockout neurons. The ability of additional copies of sybII to fully rescue presynaptic performance in these knockout neurons suggests that the principal role of synaptophysin is to mediate the efficient retrieval of sybII to sustain neurotransmitter release. ![]()
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Affiliation(s)
- Alexandros C Kokotos
- Centre for Discovery Brain Sciences, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh, Scotland, UK, EH8 9XD.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, Scotland, UK, EH8 9XD
| | - Callista B Harper
- Centre for Discovery Brain Sciences, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh, Scotland, UK, EH8 9XD.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, Scotland, UK, EH8 9XD.,Simons Initiative for the Developing Brain, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, Scotland, UK, EH8 9XD
| | - Jamie R K Marland
- Centre for Discovery Brain Sciences, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh, Scotland, UK, EH8 9XD
| | - Karen J Smillie
- Centre for Discovery Brain Sciences, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh, Scotland, UK, EH8 9XD.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, Scotland, UK, EH8 9XD
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh, Scotland, UK, EH8 9XD.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, Scotland, UK, EH8 9XD.,Simons Initiative for the Developing Brain, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, Scotland, UK, EH8 9XD
| | - Sarah L Gordon
- The Florey Institute of Neuroscience and Mental Health, and Melbourne Dementia Research Centre, The Florey Institute for Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia
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Jin Y, Seo KH, Ko HM, Jung TW, Chung YH, Lee JH, Park HH, Kim HC, Jeong JH, Lee SH. Various approaches for measurement of synaptic vesicle endocytosis at the central nerve terminal. Arch Pharm Res 2019; 42:455-465. [PMID: 31115782 DOI: 10.1007/s12272-019-01161-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 05/16/2019] [Indexed: 10/26/2022]
Abstract
At the presynaptic terminal, neurotransmitters are stored in synaptic vesicles (SVs), which are released and recycled via exo- and endocytosis. SV endocytosis is crucial for sustaining synaptic transmission by maintaining the SV pool. Many studies have shown that presynaptic dysfunction, particularly impairment of SV endocytosis, is related to neurological disorders. Notably, the presynaptic terminal is considered to be a sensitive structure because certain presynaptic dysfunctions, manifested as impaired SV endocytosis or ultrastructural changes in the presynaptic terminal, can be observed before there is a biochemical or pathological evidence of a neurological disorder. Therefore, monitoring and assessing the presynaptic function by SV endocytosis facilitates the development of early markers for neurological disorders. In this study, we reviewed the current methods for assessing and visualizing SV endocytosis at the central nerve terminal.
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Affiliation(s)
- Yeonsun Jin
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Kyoung Hee Seo
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Hyun Myung Ko
- Department of Life Science, College of Science and Technology, Woosuk University, Jincheon, 27841, Republic of Korea
| | - Tae Woo Jung
- Research Administration Team, Seoul National University Bundang Hospital, Seongnam, Korea
| | - Yoon Hee Chung
- Department of Anatomy, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
| | - Jong Hyuk Lee
- Department of Pharmaceutical Engineering, College of Life and Health Science, Hoseo University, Asan, 31499, Republic of Korea
| | - Hyun Ho Park
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Sung Hoon Lee
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea.
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40
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Koyanagi Y, Torturo CL, Cook DC, Zhou Z, Hemmings HC. Role of specific presynaptic calcium channel subtypes in isoflurane inhibition of synaptic vesicle exocytosis in rat hippocampal neurones. Br J Anaesth 2019; 123:219-227. [PMID: 31056238 DOI: 10.1016/j.bja.2019.03.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 02/24/2019] [Accepted: 03/16/2019] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND P/Q- and N-type voltage-gated calcium channels (VGCC) are the principal subtypes mediating synaptic vesicle (SV) exocytosis. Both the degree of isoflurane inhibition of SV exocytosis and VGCC subtype expression vary between brain regions and neurotransmitter phenotype. We hypothesised that differences in VGCC subtype expression contribute to synapse-selective presynaptic effects of isoflurane. METHODS We used quantitative live-cell imaging to measure exocytosis in cultured rat hippocampal neurones after transfection of the fluorescent biosensor vGlut1-pHluorin. Selective inhibitors of P/Q- and N-type VGCCs were used to isolate subtype-specific effects of isoflurane. RESULTS Inhibition of N-type channels by 1 μM ω-conotoxin GVIA reduced SV exocytosis to 81±5% of control (n=10). Residual exocytosis mediated by P/Q-type channels was further inhibited by isoflurane to 42±4% of control (n=10). The P/Q-type channel inhibitor ω-agatoxin IVA at 0.4 μM inhibited SV exocytosis to 29±3% of control (n=10). Residual exocytosis mediated by N-type channels was further inhibited by isoflurane to 17±3% of control (n=10). Analysis of isoflurane effects at the level of individual boutons revealed no difference in sensitivity to isoflurane between P/Q- or N-type channel-mediated SV exocytosis (P=0.35). There was no correlation between the effect of agatoxin (P=0.91) or conotoxin (P=0.15) and the effect of isoflurane on exocytosis. CONCLUSIONS Sensitivity of SV exocytosis to isoflurane in rat hippocampal neurones is independent of the specific VGCC subtype coupled to exocytosis. The differential sensitivity of VGCC subtypes to isoflurane does not explain the observed neurotransmitter-selective effects of isoflurane in hippocampus.
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Affiliation(s)
- Yuko Koyanagi
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA; Department of Anesthesiology, Nihon University School of Dentistry, Tokyo, Japan
| | | | - Daniel C Cook
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA
| | - Zhenyu Zhou
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA
| | - Hugh C Hemmings
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA; Department of Pharmacology, Weill Cornell Medicine, New York, NY, USA.
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41
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Hirano T. Visualization of Exo- and Endocytosis of AMPA Receptors During Hippocampal Synaptic Plasticity Around Postsynaptic-Like Membrane Formed on Glass Surface. Front Cell Neurosci 2018; 12:442. [PMID: 30519162 PMCID: PMC6258823 DOI: 10.3389/fncel.2018.00442] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 11/05/2018] [Indexed: 11/13/2022] Open
Abstract
Regulation of exo- and endocytosis of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptor (AMPAR) plays a critical role in the expression of synaptic plasticity such as long-term potentiation (LTP) and long-term depression (LTD) at excitatory central synapses. Enhanced AMPAR exocytosis or endocytosis has been suggested to contribute to LTP or LTD, respectively. However, several unsettled fundamental questions have remained about AMPAR exo- and endocytosis in the basal condition and during synaptic plasticity: (1) Does the size of each exo- or endocytosis event, and/or do the frequencies of these events change during LTP or LTD? If they change, what are the time courses of the respective changes? (2) Where does the exo- or endocytosis preferentially occur in each condition: inside or in the vicinity of postsynaptic membrane, or in the extrasynaptic membrane? (3) Do different types of AMPAR, such as GluA1 homo-tetramer, GluA1/2 hetero-tetramer and GluA2/3 hetero-tetramer, show distinct exo- and endocytosis changes? To address these questions, we developed new methods to observe individual events of AMPAR exo- or endocytosis with a high signal to noise (SN) ratio in a culture preparation using total internal reflection fluorescence microscopy (TIRFM). In these studies, hippocampal neurons were cultured on a neurexin (NRX)-coated glass coverslip, which induced formation of postsynaptic-like membrane (PSLM) directly on the glass surface. Then, a super-ecliptic pHluorin (SEP)-tagged AMPAR subunit such as GluA1 (GluA1-SEP) was expressed in neurons and its fluorescence changes during LTP induced by high frequency electrical field stimulation were observed with TIRFM, which showed different time courses of exocytosis changes of GluA1-, GluA2-, or GluA3-SEP in and around PSLM. In addition, a new method to detect individual endocytosis events of AMPAR was developed by combining TIFRM observation of GluA-SEP around PSLM with a rapid extracellular pH exchange method using a U-tube. Recent results on exo- and endocytosis changes of GluA-SEP during N-methyl-D-aspartate (NMDA)-induced LTD suggested that suppression of AMPAR exocytosis rather than enhancement of AMPAR endocytosis primarily contributes to LTD expression, although the NMDA application transiently enhances clathrin-dependent endocytosis of GluA1-containing AMPAR.
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Affiliation(s)
- Tomoo Hirano
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
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42
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Mietkowska M, Schuberth C, Wedlich-Söldner R, Gerke V. Actin dynamics during Ca 2+-dependent exocytosis of endothelial Weibel-Palade bodies. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:1218-1229. [PMID: 30465794 DOI: 10.1016/j.bbamcr.2018.11.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/14/2018] [Accepted: 11/15/2018] [Indexed: 01/24/2023]
Abstract
Weibel-Palade bodies (WPBs) are specialized secretory organelles of endothelial cells that serve important functions in the response to inflammation and vascular injury. WPBs actively respond to different stimuli by regulated exocytosis leading to full or selective release of their contents. Cellular conditions and mechanisms that distinguish between these possibilities are only beginning to emerge. To address this we analyzed dynamic rearrangements of the actin cytoskeleton during histamine-stimulated, Ca2+-dependent WPB exocytosis. We show that most WPB fusion events are followed by a rapid release of von-Willebrand factor (VWF), the large WPB cargo, and that this occurs concomitant with a softening of the actin cortex by the recently described Ca2+-dependent actin reset (CaAR). However, a considerable fraction of WPB fusion events is characterized by a delayed release of VWF and observed after the CaAR reaction peak. These delayed VWF secretions are accompanied by an assembly of actin rings or coats around the WPB post-fusion structures and are also seen following direct elevation of intracellular Ca2+ by plasma membrane wounding. Actin ring/coat assembly at WPB post-fusion structures requires Rho GTPase activity and is significantly reduced upon expression of a dominant-active mutant of the formin INF2 that triggers a permanent CaAR peak-like sequestration of actin to the endoplasmic reticulum. These findings suggest that a rigid actin cortex correlates with a higher proportion of fused WPB which assemble actin rings/coats most likely required for efficient VWF expulsion and/or stabilization of a WPB post-fusion structure. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.
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Affiliation(s)
- Magdalena Mietkowska
- Institute of Medical Biochemistry, Centre for Molecular Biology of Inflammation and Cells-in-Motion Cluster of Excellence, University of Münster, Germany
| | - Christian Schuberth
- Institute of Cell Dynamics and Imaging, Centre for Molecular Biology of Inflammation and Cells-in-Motion Cluster of Excellence, University of Münster, Germany
| | - Roland Wedlich-Söldner
- Institute of Cell Dynamics and Imaging, Centre for Molecular Biology of Inflammation and Cells-in-Motion Cluster of Excellence, University of Münster, Germany
| | - Volker Gerke
- Institute of Medical Biochemistry, Centre for Molecular Biology of Inflammation and Cells-in-Motion Cluster of Excellence, University of Münster, Germany.
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Development of lentiviral vectors for efficient glutamatergic-selective gene expression in cultured hippocampal neurons. Sci Rep 2018; 8:15156. [PMID: 30310105 PMCID: PMC6181963 DOI: 10.1038/s41598-018-33509-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 10/01/2018] [Indexed: 01/11/2023] Open
Abstract
Targeting gene expression to a particular subset of neurons helps study the cellular function of the nervous system. Although neuron-specific promoters, such as the synapsin I promoter and the α-CaMKII promoter, are known to exhibit selectivity for excitatory glutamatergic neurons in vivo, the cell type-specificity of these promoters has not been thoroughly tested in culture preparations. Here, by using hippocampal culture preparation from the VGAT-Venus transgenic mice, we examined the ability of five putative promoter sequences of glutamatergic-selective markers including synapsin I, α-CaMKII, the vesicular glutamate transporter 1 (VGLUT1), Dock10 and Prox1. Among these, a genomic fragment containing a 2.1 kb segment upstream of the translation start site (TSS) of the VGLUT1 implemented in a lentiviral vector with the Tet-Off inducible system achieved the highest preferential gene expression in glutamatergic neurons. Analysis of various lengths of the VGLUT1 promoter regions identified a segment between −2.1 kb and −1.4 kb from the TSS as a responsible element for the glutamatergic selectivity. Consistently, expression of channelrhodopsin under this promoter sequence allowed for selective light-evoked activation of excitatory neurons. Thus, the lentiviral system carrying the VGLUT1 promoter fragment can be used to effectively target exogenous gene expression to excitatory glutamatergic neurons in cultures.
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Activity-dependent bulk endocytosis proteome reveals a key presynaptic role for the monomeric GTPase Rab11. Proc Natl Acad Sci U S A 2018; 115:E10177-E10186. [PMID: 30301801 PMCID: PMC6205440 DOI: 10.1073/pnas.1809189115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The maintenance of neurotransmission by synaptic vesicle (SV) recycling is critical to brain function. The dominant SV recycling mode during intense activity is activity-dependent bulk endocytosis (ADBE), suggesting it will perform a pivotal role in neurotransmission. However, the role of ADBE is still undetermined, due to the absence of identified molecules specific for this process. The determination of the bulk endosome proteome (a key ADBE organelle) revealed that it has a unique molecular signature and identified a role for Rab11 in presynaptic function. This work provides the molecular inventory of ADBE, a resource that will be of significant value to researchers wishing to modulate neurotransmission during intense neuronal activity in both health and disease. Activity-dependent bulk endocytosis (ADBE) is the dominant mode of synaptic vesicle endocytosis during high-frequency stimulation, suggesting it should play key roles in neurotransmission during periods of intense neuronal activity. However, efforts in elucidating the physiological role of ADBE have been hampered by the lack of identified molecules which are unique to this endocytosis mode. To address this, we performed proteomic analysis on purified bulk endosomes, which are a key organelle in ADBE. Bulk endosomes were enriched via two independent approaches, a classical subcellular fractionation method and isolation via magnetic nanoparticles. There was a 77% overlap in proteins identified via the two protocols, and these molecules formed the ADBE core proteome. Bioinformatic analysis revealed a strong enrichment in cell adhesion and cytoskeletal and signaling molecules, in addition to expected synaptic and trafficking proteins. Network analysis identified Rab GTPases as a central hub within the ADBE proteome. Subsequent investigation of a subset of these Rabs revealed that Rab11 both facilitated ADBE and accelerated clathrin-mediated endocytosis. These findings suggest that the ADBE proteome will provide a rich resource for the future study of presynaptic function, and identify Rab11 as a regulator of presynaptic function.
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Genetic dissection of neuropeptide cell biology at high and low activity in a defined sensory neuron. Proc Natl Acad Sci U S A 2018; 115:E6890-E6899. [PMID: 29959203 PMCID: PMC6055185 DOI: 10.1073/pnas.1714610115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neuropeptides are ubiquitous modulators of behavior and physiology. They are packaged in specialized secretory organelles called dense core vesicles (DCVs) that are released upon neural stimulation. Whereas local recycling of synaptic vesicles has been investigated intensively, there are few studies on recycling of DCV proteins. We set up a paradigm to study DCVs in a neuron whose activity we can control. We validate our model by confirming many previous observations on DCV cell biology. We identify a set of genes involved in recycling of DCV proteins. We also find evidence that different mechanisms of DCV priming and exocytosis may operate at high and low neural activity. Neuropeptides are ubiquitous modulators of behavior and physiology. They are packaged in specialized secretory organelles called dense core vesicles (DCVs) that are released upon neural stimulation. Unlike synaptic vesicles, which can be recycled and refilled close to release sites, DCVs must be replenished by de novo synthesis in the cell body. Here, we dissect DCV cell biology in vivo in a Caenorhabditis elegans sensory neuron whose tonic activity we can control using a natural stimulus. We express fluorescently tagged neuropeptides in the neuron and define parameters that describe their subcellular distribution. We measure these parameters at high and low neural activity in 187 mutants defective in proteins implicated in membrane traffic, neuroendocrine secretion, and neuronal or synaptic activity. Using unsupervised hierarchical clustering methods, we analyze these data and identify 62 groups of genes with similar mutant phenotypes. We explore the function of a subset of these groups. We recapitulate many previous findings, validating our paradigm. We uncover a large battery of proteins involved in recycling DCV membrane proteins, something hitherto poorly explored. We show that the unfolded protein response promotes DCV production, which may contribute to intertissue communication of stress. We also find evidence that different mechanisms of priming and exocytosis may operate at high and low neural activity. Our work provides a defined framework to study DCV biology at different neural activity levels.
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Gan Q, Watanabe S. Synaptic Vesicle Endocytosis in Different Model Systems. Front Cell Neurosci 2018; 12:171. [PMID: 30002619 PMCID: PMC6031744 DOI: 10.3389/fncel.2018.00171] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 06/01/2018] [Indexed: 11/13/2022] Open
Abstract
Neurotransmission in complex animals depends on a choir of functionally distinct synapses releasing neurotransmitters in a highly coordinated manner. During synaptic signaling, vesicles fuse with the plasma membrane to release their contents. The rate of vesicle fusion is high and can exceed the rate at which synaptic vesicles can be re-supplied by distant sources. Thus, local compensatory endocytosis is needed to replenish the synaptic vesicle pools. Over the last four decades, various experimental methods and model systems have been used to study the cellular and molecular mechanisms underlying synaptic vesicle cycle. Clathrin-mediated endocytosis is thought to be the predominant mechanism for synaptic vesicle recycling. However, recent studies suggest significant contribution from other modes of endocytosis, including fast compensatory endocytosis, activity-dependent bulk endocytosis, ultrafast endocytosis, as well as kiss-and-run. Currently, it is not clear whether a universal model of vesicle recycling exist for all types of synapses. It is possible that each synapse type employs a particular mode of endocytosis. Alternatively, multiple modes of endocytosis operate at the same synapse, and the synapse toggles between different modes depending on its activity level. Here we compile review and research articles based on well-characterized model systems: frog neuromuscular junctions, C. elegans neuromuscular junctions, Drosophila neuromuscular junctions, lamprey reticulospinal giant axons, goldfish retinal ribbon synapses, the calyx of Held, and rodent hippocampal synapses. We will compare these systems in terms of their known modes and kinetics of synaptic vesicle endocytosis, as well as the underlying molecular machineries. We will also provide the future development of this field.
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Affiliation(s)
- Quan Gan
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Shigeki Watanabe
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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Riemann D, Petkova A, Dresbach T, Wallrafen R. An Optical Assay for Synaptic Vesicle Recycling in Cultured Neurons Overexpressing Presynaptic Proteins. J Vis Exp 2018:58043. [PMID: 30010661 PMCID: PMC6101998 DOI: 10.3791/58043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
At active presynaptic nerve terminals, synaptic vesicles undergo cycles of exo- and endocytosis. During recycling, the luminal domains of SV transmembrane proteins become exposed at the cell surface. One of these proteins is Synaptotagmin-1 (Syt1). An antibody directed against the luminal domain of Syt1, once added to the culture medium, is taken up during the exo-endocytotic cycle. This uptake is proportional to the amount of SV recycling and can be quantified through immunofluorescence. Here, we combine Syt1 antibody uptake with double transfection of cultured hippocampal neurons. This allows us to (1) localize presynaptic sites based on expression of recombinant presynaptic marker Synaptophysin, (2) determine their functionality using Syt1 uptake, and (3) characterize the targeting and effects of a protein of interest, GFP-Rogdi.
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Affiliation(s)
- Donatus Riemann
- Institute for Anatomy and Embryology, University Medical Centre Göttingen
| | - Andoniya Petkova
- Institute for Anatomy and Embryology, University Medical Centre Göttingen
| | - Thomas Dresbach
- Institute for Anatomy and Embryology, University Medical Centre Göttingen;
| | - Rebecca Wallrafen
- Institute for Anatomy and Embryology, University Medical Centre Göttingen
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48
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Somasundaram A, Taraska JW. Local protein dynamics during microvesicle exocytosis in neuroendocrine cells. Mol Biol Cell 2018; 29:1891-1903. [PMID: 29874123 PMCID: PMC6085826 DOI: 10.1091/mbc.e17-12-0716] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Calcium-triggered exocytosis is key to many physiological processes, including neurotransmitter and hormone release by neurons and endocrine cells. Dozens of proteins regulate exocytosis, yet the temporal and spatial dynamics of these factors during vesicle fusion remain unclear. Here we use total internal reflection fluorescence microscopy to visualize local protein dynamics at single sites of exocytosis of small synaptic-like microvesicles in live cultured neuroendocrine PC12 cells. We employ two-color imaging to simultaneously observe membrane fusion (using vesicular acetylcholine ACh transporter tagged to pHluorin) and the dynamics of associated proteins at the moments surrounding exocytosis. Our experiments show that many proteins, including the SNAREs syntaxin1 and VAMP2, the SNARE modulator tomosyn, and Rab proteins, are preclustered at fusion sites and rapidly lost at fusion. The ATPase N-ethylmaleimide–sensitive factor is locally recruited at fusion. Interestingly, the endocytic Bin-Amphiphysin-Rvs domain–containing proteins amphiphysin1, syndapin2, and endophilins are dynamically recruited to fusion sites and slow the loss of vesicle membrane-bound cargo from fusion sites. A similar effect on vesicle membrane protein dynamics was seen with the overexpression of the GTPases dynamin1 and dynamin2. These results suggest that proteins involved in classical clathrin-mediated endocytosis can regulate exocytosis of synaptic-like microvesicles. Our findings provide insights into the dynamics, assembly, and mechanistic roles of many key factors of exocytosis and endocytosis at single sites of microvesicle fusion in live cells.
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Affiliation(s)
- Agila Somasundaram
- Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Justin W Taraska
- Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
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49
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Funahashi J, Tanaka H, Hirano T. Visualization of Synchronous or Asynchronous Release of Single Synaptic Vesicle in Active-Zone-Like Membrane Formed on Neuroligin-Coated Glass Surface. Front Cell Neurosci 2018; 12:140. [PMID: 29875634 PMCID: PMC5974336 DOI: 10.3389/fncel.2018.00140] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 05/07/2018] [Indexed: 11/14/2022] Open
Abstract
Fast repetitive synaptic transmission depends on efficient exocytosis and retrieval of synaptic vesicles around a presynaptic active zone. However, the functional organization of an active zone and regulatory mechanisms of exocytosis, endocytosis and reconstruction of release-competent synaptic vesicles have not been fully elucidated. By developing a novel visualization method, we attempted to identify the location of exocytosis of a single synaptic vesicle within an active zone and examined movement of synaptic vesicle protein synaptophysin (Syp) after exocytosis. Using cultured hippocampal neurons, we induced formation of active-zone-like membranes (AZLMs) directly adjacent and parallel to a glass surface coated with neuroligin, and imaged Syp fused to super-ecliptic pHluorin (Syp-SEP) after its translocation to the plasma membrane from a synaptic vesicle using total internal reflection fluorescence microscopy (TIRFM). An AZLM showed characteristic molecular and functional properties of a presynaptic active zone. It contained active zone proteins, cytomatrix at the active zone-associated structural protein (CAST), Bassoon, Piccolo, Munc13 and RIM, and showed an increase in intracellular Ca2+ concentration upon electrical stimulation. In addition, single-pulse stimulation sometimes induced a transient increase of Syp-SEP signal followed by lateral spread in an AZLM, which was considered to reflect an exocytosis event of a single synaptic vesicle. The diffusion coefficient of Syp-SEP on the presynaptic plasma membrane after the membrane fusion was estimated to be 0.17–0.19 μm2/s, suggesting that Syp-SEP diffused without significant obstruction. Synchronous exocytosis just after the electrical stimulation tended to occur at multiple restricted sites within an AZLM, whereas locations of asynchronous release occurring later after the stimulation tended to be more scattered.
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Affiliation(s)
- Junichiro Funahashi
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Hiromitsu Tanaka
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Tomoo Hirano
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
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50
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Kong D, Tian X, Li Y, Zhang S, Cheng Y, Huo L, Ma H, Yang Z, Ren L, Zhang M, Zhang W. Revealing the Inhibitory Effect of Ginseng on Mitochondrial Respiration through Synaptosomal Proteomics. Proteomics 2018; 18:e1700354. [PMID: 29687596 DOI: 10.1002/pmic.201700354] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 01/19/2018] [Indexed: 12/25/2022]
Abstract
Ginseng, the active ingredients of which are ginsenosides, is the most popular herbal medicine and has potential merit in the treatment of cerebral disorders. To better understand the function of Ginseng in the cerebral system, we examined changes in the protein expression profiles of synaptosomes extracted from the cerebral cortical and hippocampal tissues of rats administered a high or low dose of Ginseng for 2 weeks. More than 5000 proteins belonging to synaptosomes were simultaneously identified and quantitated by an approach combining tandem mass tags with 2D liquid chromatography-mass spectrometry (LC-MS). Regarding differentially expressed proteins, downregulated proteins were much more highly induced than upregulators in the cerebral cortical and hippocampal synaptosomes, regardless of the dose of Ginseng. Bioinformatic analysis indicated the majority of the altered proteins to be located in the mitochondria, directly or indirectly affecting mitochondrial oxidative respiration. Further functional experiments using the substrate-uncoupler inhibitor titration approach confirmed that three representative ginsenosides were able to inhibit oxidative phosphorylation in mitochondria. Our results demonstrate that Ginseng can regulate the function of mitochondria and alter the energy metabolism of cells, which may be useful for the treatment of central nervous disorders.
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Affiliation(s)
- Dezhi Kong
- Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, 050017, P. R. China
| | - Xiaolin Tian
- Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, 050017, P. R. China
| | - Yunshan Li
- Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, 050017, P. R. China
| | - Saihang Zhang
- Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, 050017, P. R. China
| | - Yiru Cheng
- Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, 050017, P. R. China
| | - Lifang Huo
- Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, 050017, P. R. China
| | - Huanhuan Ma
- Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, 050017, P. R. China
| | - Zuxiao Yang
- Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, 050017, P. R. China
| | - Leiming Ren
- Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, 050017, P. R. China
| | - Mingquan Zhang
- Department of Basic Theory of Chinese Medicine, Hebei University of Chinese Medicine, Shijiazhuang, 050017, P. R. China
| | - Wei Zhang
- Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, 050017, P. R. China
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