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Grothe T, Walla PJ. Fluorescence Lifetime and Cross-correlation Spectroscopy for Observing Membrane Fusion of Liposome Models Containing Synaptic Proteins. Methods Mol Biol 2022; 2417:167-180. [PMID: 35099799 DOI: 10.1007/978-1-0716-1916-2_13] [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: 06/14/2023]
Abstract
Watching events of membrane fusion in real time and distinguishing between intermediate steps of these events is useful for mechanistic insights but at the same time a challenging task. In this chapter, we describe how to use fluorescence cross-correlation spectroscopy and Förster-resonance energy transfer to resolve the tethering and fusion of membranes by SNARE proteins (syntaxin-1, SNAP-25, and synaptobrevin-2) as an example. The given protocols can easily be adapted to other membrane proteins to investigate their ability to tether or even fuse vesicular membrane.
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Affiliation(s)
- Tobias Grothe
- Laboratory of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
- Department of Biophysical Chemistry, Institute for Physical and Theoretical Chemistry, TU Braunschweig, Braunschweig, Germany
| | - Peter J Walla
- Laboratory of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany.
- Department of Biophysical Chemistry, Institute for Physical and Theoretical Chemistry, TU Braunschweig, Braunschweig, Germany.
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2
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Dhara M, Mohrmann R, Bruns D. v-SNARE function in chromaffin cells. Pflugers Arch 2017; 470:169-180. [PMID: 28887593 PMCID: PMC5748422 DOI: 10.1007/s00424-017-2066-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 08/28/2017] [Accepted: 08/29/2017] [Indexed: 01/04/2023]
Abstract
Vesicle fusion is elementary for intracellular trafficking and release of signal molecules, thus providing the basis for diverse forms of intercellular communication like hormonal regulation or synaptic transmission. A detailed characterization of the mechanisms underlying exocytosis is key to understand how the nervous system integrates information and generates appropriate responses to stimuli. The machinery for vesicular release employs common molecular players in different model systems including neuronal and neuroendocrine cells, in particular members of the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) protein family, Sec1/Munc18-like proteins, and other accessory factors. To achieve temporal precision and speed, excitable cells utilize specialized regulatory proteins like synaptotagmin and complexin, whose interplay putatively synchronizes vesicle fusion and enhances stimulus-secretion coupling. In this review, we aim to highlight recent progress and emerging views on the molecular mechanisms, by which constitutively forming SNAREpins are organized in functional, tightly regulated units for synchronized release. Specifically, we will focus on the role of vesicle associated membrane proteins, also referred to as vesicular SNAREs, in fusion and rapid cargo discharge. We will further discuss the functions of SNARE regulators during exocytosis and focus on chromaffin cell as a model system of choice that allows for detailed structure-function analyses and direct measurements of vesicle fusion under precise control of intracellular [Ca]i.
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Affiliation(s)
- Madhurima Dhara
- Molecular Neurophysiology, CIPMM, Medical Faculty, Saarland University, 66421, Homburg/Saar, Germany
| | - Ralf Mohrmann
- Zentrum für Human- und Molekularbiologie, Saarland University, 66421, Homburg/Saar, Germany
| | - Dieter Bruns
- Molecular Neurophysiology, CIPMM, Medical Faculty, Saarland University, 66421, Homburg/Saar, Germany.
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3
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Kunii M, Ohara-Imaizumi M, Takahashi N, Kobayashi M, Kawakami R, Kondoh Y, Shimizu T, Simizu S, Lin B, Nunomura K, Aoyagi K, Ohno M, Ohmuraya M, Sato T, Yoshimura SI, Sato K, Harada R, Kim YJ, Osada H, Nemoto T, Kasai H, Kitamura T, Nagamatsu S, Harada A. Opposing roles for SNAP23 in secretion in exocrine and endocrine pancreatic cells. J Cell Biol 2016; 215:121-138. [PMID: 27697926 PMCID: PMC5057288 DOI: 10.1083/jcb.201604030] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 08/26/2016] [Indexed: 12/17/2022] Open
Abstract
Kunii et al. reveal that the SNARE protein SNAP23 plays distinct roles in the secretion of amylase in exocrine cells and of insulin in endocrine cells the pancreas and show that MF286, a novel inhibitor of SNAP23, may be a new drug candidate for diabetes. The membrane fusion of secretory granules with plasma membranes is crucial for the exocytosis of hormones and enzymes. Secretion disorders can cause various diseases such as diabetes or pancreatitis. Synaptosomal-associated protein 23 (SNAP23), a soluble N-ethyl-maleimide sensitive fusion protein attachment protein receptor (SNARE) molecule, is essential for secretory granule fusion in several cell lines. However, the in vivo functions of SNAP23 in endocrine and exocrine tissues remain unclear. In this study, we show opposing roles for SNAP23 in secretion in pancreatic exocrine and endocrine cells. The loss of SNAP23 in the exocrine and endocrine pancreas resulted in decreased and increased fusion of granules to the plasma membrane after stimulation, respectively. Furthermore, we identified a low molecular weight compound, MF286, that binds specifically to SNAP23 and promotes insulin secretion in mice. Our results demonstrate opposing roles for SNAP23 in the secretion mechanisms of the endocrine and exocrine pancreas and reveal that the SNAP23-binding compound MF286 may be a promising drug for diabetes treatment.
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Affiliation(s)
- Masataka Kunii
- Laboratory of Molecular Traffic, Department of Molecular and Cellular Biology, Institute for Molecular and Cellular Regulation, Gunma University, Gunma 371-8512, Japan Department of Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Mica Ohara-Imaizumi
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo 181-8611, Japan
| | - Noriko Takahashi
- Laboratory of Structural Physiology, Graduate School of Medicine, Center for Disease Biology and Integrative Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Masaki Kobayashi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma 371-8512, Japan
| | - Ryosuke Kawakami
- Laboratory of Molecular and Cellular Biophysics, Research Institute for Electronic Science, Hokkaido University, Hokkaido 001-0020, Japan
| | - Yasumitsu Kondoh
- Chemical Biology Research Group, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Takeshi Shimizu
- Chemical Biology Research Group, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Siro Simizu
- Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Kanagawa 223-8522, Japan
| | - Bangzhong Lin
- Drug Discovery Team, Office for University-Industry Collaboration Planning and Promotion, Osaka University, Osaka 565-0871, Japan
| | - Kazuto Nunomura
- Drug Discovery Team, Office for University-Industry Collaboration Planning and Promotion, Osaka University, Osaka 565-0871, Japan
| | - Kyota Aoyagi
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo 181-8611, Japan
| | - Mitsuyo Ohno
- Laboratory of Structural Physiology, Graduate School of Medicine, Center for Disease Biology and Integrative Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Masaki Ohmuraya
- Institute of Resource Development and Analysis, Kumamoto University, Kumamoto 860-0811, Japan
| | - Takashi Sato
- Laboratory of Molecular Traffic, Department of Molecular and Cellular Biology, Institute for Molecular and Cellular Regulation, Gunma University, Gunma 371-8512, Japan
| | - Shin-Ichiro Yoshimura
- Department of Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Ken Sato
- Laboratory of Molecular Traffic, Department of Molecular and Cellular Biology, Institute for Molecular and Cellular Regulation, Gunma University, Gunma 371-8512, Japan
| | - Reiko Harada
- Department of Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan Department of Judo Therapy, Takarazuka University of Medical and Health Care, Hyogo 666-0152, Japan
| | - Yoon-Jeong Kim
- Drug Discovery Team, Office for University-Industry Collaboration Planning and Promotion, Osaka University, Osaka 565-0871, Japan
| | - Hiroyuki Osada
- Chemical Biology Research Group, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Tomomi Nemoto
- Laboratory of Molecular and Cellular Biophysics, Research Institute for Electronic Science, Hokkaido University, Hokkaido 001-0020, Japan
| | - Haruo Kasai
- Laboratory of Structural Physiology, Graduate School of Medicine, Center for Disease Biology and Integrative Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Tadahiro Kitamura
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma 371-8512, Japan
| | - Shinya Nagamatsu
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo 181-8611, Japan
| | - Akihiro Harada
- Laboratory of Molecular Traffic, Department of Molecular and Cellular Biology, Institute for Molecular and Cellular Regulation, Gunma University, Gunma 371-8512, Japan Department of Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
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Crawford DC, Kavalali ET. Molecular underpinnings of synaptic vesicle pool heterogeneity. Traffic 2015; 16:338-64. [PMID: 25620674 DOI: 10.1111/tra.12262] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 01/06/2015] [Indexed: 12/31/2022]
Abstract
Neuronal communication relies on chemical synaptic transmission for information transfer and processing. Chemical neurotransmission is initiated by synaptic vesicle fusion with the presynaptic active zone resulting in release of neurotransmitters. Classical models have assumed that all synaptic vesicles within a synapse have the same potential to fuse under different functional contexts. In this model, functional differences among synaptic vesicle populations are ascribed to their spatial distribution in the synapse with respect to the active zone. Emerging evidence suggests, however, that synaptic vesicles are not a homogenous population of organelles, and they possess intrinsic molecular differences and differential interaction partners. Recent studies have reported a diverse array of synaptic molecules that selectively regulate synaptic vesicles' ability to fuse synchronously and asynchronously in response to action potentials or spontaneously irrespective of action potentials. Here we discuss these molecular mediators of vesicle pool heterogeneity that are found on the synaptic vesicle membrane, on the presynaptic plasma membrane, or within the cytosol and consider some of the functional consequences of this diversity. This emerging molecular framework presents novel avenues to probe synaptic function and uncover how synaptic vesicle pools impact neuronal signaling.
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Affiliation(s)
- Devon C Crawford
- Department of Neuroscience, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9111, USA
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Prashad RC, Charlton MP. SNARE zippering and synaptic strength. PLoS One 2014; 9:e95130. [PMID: 24747882 PMCID: PMC3991612 DOI: 10.1371/journal.pone.0095130] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 03/25/2014] [Indexed: 01/26/2023] Open
Abstract
Synapses vary widely in the probability of neurotransmitter release. We tested the hypothesis that the zippered state of the trans-SNARE (Soluble N-ethylmaleimide-sensitive factor Attachment protein REceptor) complex determines initial release probability. We tested this hypothesis at phasic and tonic synapses which differ by 100-1000-fold in neurotransmitter release probability. We injected, presynaptically, three Clostridial neurotoxins which bind and cleave at different sites on VAMP to determine whether these sites were occluded by the zippering of the SNARE complex or open to proteolytic attack. Under low stimulation conditions, the catalytic light-chain fragment of botulinum B (BoNT/B-LC) inhibited evoked release at both phasic and tonic synapses and cleaved VAMP; however, neither BoNT/D-LC nor tetanus neurotoxin (TeNT-LC) were effective in these conditions. The susceptibility of VAMP to only BoNT/B-LC indicated that SNARE complexes at both phasic and tonic synapses were partially zippered only at the N-terminal end to approximately the zero-layer with the C-terminal end exposed under resting state. Therefore, the existence of the same partially zippered state of the trans-SNARE complex at both phasic and tonic synapses indicates that release probability is not determined solely by the zippered state of the trans-SNARE complex at least to the zero-layer.
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Affiliation(s)
- Rene C. Prashad
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Milton P. Charlton
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Kashiwada A, Tsuboi M, Matsuda K. Target-selective one-way membrane fusion system based on a pH-responsive coiled coil assembly at the interface of liposomal vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:1403-1408. [PMID: 21058731 DOI: 10.1021/la103908u] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The coiled coil trimer structure is a common motif observed in membrane fusion processes of specific fusion proteins such as the hemagglutinin glycoprotein. The HA2 subunit in the hemagglutinin changes its conformation or geometry to be favorable to membrane fusion in response to endosomal weakly acidic pH. This pH responsiveness is indispensable to an artificial polypeptide-triggered delivery system as well as the membrane fusion reaction in biology. In this study, we have constructed an AAB-type coiled coil heteroassembled system that is sensitive to weakly acidic pH. The heterotrimer is formed from two kinds of polypeptides containing an Ala or a Trp residue at a hydrophobic a position, and it was observed that the Glu residue at the other a position induced an acidic pH-dependent conformational change. On the basis of this pH-responsive coiled coil heteroassembled system, a boronic acid coupled working polypeptide for the combination of an intervesicular complex with a sugarlike compound on the surface of the target liposome, and a supporting polypeptide for the construction of a pH-responsive heterotrimer with the working polypeptide were designed and synthesized. The process of membrane fusion was characterized by lipid-mixing, inner-leaflet lipid-mixing, and content-mixing assays. The target selective vesicle fusion is clearly observed at a weakly acidic pH, where the working polypeptides form a heterotrimeric coiled coil with the supporting polypeptides in a 1:2 binding stoichiometry and the surfaces between pilot and target vesicles come into close proximity to each other.
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Affiliation(s)
- Ayumi Kashiwada
- Department of Applied Molecular Chemistry, Graduate School of Industrial Technology, Nihon University, Narashino, Chiba, Japan.
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Zhao P, Yang L, Lopez JA, Fan J, Burchfield JG, Bai L, Hong W, Xu T, James DE. Variations in the requirement for v-SNAREs in GLUT4 trafficking in adipocytes. J Cell Sci 2009; 122:3472-80. [PMID: 19759285 DOI: 10.1242/jcs.047449] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Vesicle transport in eukaryotic cells is regulated by SNARE proteins, which play an intimate role in regulating the specificity of vesicle fusion between discrete intracellular organelles. In the present study we investigated the function and plasticity of v-SNAREs in insulin-regulated GLUT4 trafficking in adipocytes. Using a combination of knockout mice, v-SNARE cleavage by clostridial toxins and total internal reflection fluorescence microscopy, we interrogated the function of VAMPs 2, 3 and 8 in this process. Our studies reveal that the simultaneous disruption of VAMPs 2, 3 and 8 completely inhibited insulin-stimulated GLUT4 insertion into the plasma membrane, due to a block in vesicle docking at the plasma membrane. These defects could be rescued by re-expression of VAMP2, VAMP3 or VAMP8 alone, but not VAMP7. These data indicate a plasticity in the requirement for v-SNAREs in GLUT4 trafficking to the plasma membrane and further define an important role for the v-SNARE proteins in pre-fusion docking of vesicles.
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Affiliation(s)
- Ping Zhao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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