1
|
An D, Lindau M. Exploring the structural dynamics of the vesicle priming machinery. Biochem Soc Trans 2024; 52:1715-1725. [PMID: 39082978 DOI: 10.1042/bst20231333] [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] [Indexed: 08/29/2024]
Abstract
Various cell types release neurotransmitters, hormones and many other compounds that are stored in secretory vesicles by exocytosis via the formation of a fusion pore traversing the vesicular membrane and the plasma membrane. This process of membrane fusion is mediated by the Soluble N-ethylmaleimide-Sensitive Factor Attachment Proteins REceptor (SNARE) protein complex, which in neurons and neuroendocrine cells is composed of the vesicular SNARE protein Synaptobrevin and the plasma membrane proteins Syntaxin and SNAP25 (Synaptosomal-Associated Protein of 25 kDa). Before a vesicle can undergo fusion and release of its contents, it must dock at the plasma membrane and undergo a process named 'priming', which makes it ready for release. The primed vesicles form the readily releasable pool, from which they can be rapidly released in response to stimulation. The stimulus is an increase in Ca2+ concentration near the fusion site, which is sensed primarily by the vesicular Ca2+ sensor Synaptotagmin. Vesicle priming involves at least the SNARE proteins as well as Synaptotagmin and the accessory proteins Munc18, Munc13, and Complexin but additional proteins may also participate in this process. This review discusses the current views of the interactions and the structural changes that occur among the proteins of the vesicle priming machinery.
Collapse
Affiliation(s)
- Dong An
- Department of Physiology and Biophysics, University of Miami School of Medicine, Miami, FL 33136, U.S.A
| | - Manfred Lindau
- Department of Physiology and Biophysics, University of Miami School of Medicine, Miami, FL 33136, U.S.A
| |
Collapse
|
2
|
Palfreyman MT, West SE, Jorgensen EM. SNARE Proteins in Synaptic Vesicle Fusion. ADVANCES IN NEUROBIOLOGY 2023; 33:63-118. [PMID: 37615864 DOI: 10.1007/978-3-031-34229-5_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Neurotransmitters are stored in small membrane-bound vesicles at synapses; a subset of synaptic vesicles is docked at release sites. Fusion of docked vesicles with the plasma membrane releases neurotransmitters. Membrane fusion at synapses, as well as all trafficking steps of the secretory pathway, is mediated by SNARE proteins. The SNAREs are the minimal fusion machinery. They zipper from N-termini to membrane-anchored C-termini to form a 4-helix bundle that forces the apposed membranes to fuse. At synapses, the SNAREs comprise a single helix from syntaxin and synaptobrevin; SNAP-25 contributes the other two helices to complete the bundle. Unc13 mediates synaptic vesicle docking and converts syntaxin into the permissive "open" configuration. The SM protein, Unc18, is required to initiate and proofread SNARE assembly. The SNAREs are then held in a half-zippered state by synaptotagmin and complexin. Calcium removes the synaptotagmin and complexin block, and the SNAREs drive vesicle fusion. After fusion, NSF and alpha-SNAP unwind the SNAREs and thereby recharge the system for further rounds of fusion. In this chapter, we will describe the discovery of the SNAREs, their relevant structural features, models for their function, and the central role of Unc18. In addition, we will touch upon the regulation of SNARE complex formation by Unc13, complexin, and synaptotagmin.
Collapse
Affiliation(s)
- Mark T Palfreyman
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Sam E West
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Erik M Jorgensen
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA.
| |
Collapse
|
3
|
Meunier FA, Hu Z. Functional Roles of UNC-13/Munc13 and UNC-18/Munc18 in Neurotransmission. ADVANCES IN NEUROBIOLOGY 2023; 33:203-231. [PMID: 37615868 DOI: 10.1007/978-3-031-34229-5_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Neurotransmitters are released from synaptic and secretory vesicles following calcium-triggered fusion with the plasma membrane. These exocytotic events are driven by assembly of a ternary SNARE complex between the vesicle SNARE synaptobrevin and the plasma membrane-associated SNAREs syntaxin and SNAP-25. Proteins that affect SNARE complex assembly are therefore important regulators of synaptic strength. In this chapter, we review our current understanding of the roles played by two SNARE interacting proteins: UNC-13/Munc13 and UNC-18/Munc18. We discuss results from both invertebrate and vertebrate model systems, highlighting recent advances, focusing on the current consensus on molecular mechanisms of action and nanoscale organization, and pointing out some unresolved aspects of their functions.
Collapse
Affiliation(s)
- Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia.
| | - Zhitao Hu
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.
| |
Collapse
|
4
|
Synaptic Secretion and Beyond: Targeting Synapse and Neurotransmitters to Treat Neurodegenerative Diseases. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:9176923. [PMID: 35923862 PMCID: PMC9343216 DOI: 10.1155/2022/9176923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 05/16/2022] [Accepted: 06/04/2022] [Indexed: 11/17/2022]
Abstract
The nervous system is important, because it regulates the physiological function of the body. Neurons are the most basic structural and functional unit of the nervous system. The synapse is an asymmetric structure that is important for neuronal function. The chemical transmission mode of the synapse is realized through neurotransmitters and electrical processes. Based on vesicle transport, the abnormal information transmission process in the synapse can lead to a series of neurorelated diseases. Numerous proteins and complexes that regulate the process of vesicle transport, such as SNARE proteins, Munc18-1, and Synaptotagmin-1, have been identified. Their regulation of synaptic vesicle secretion is complicated and delicate, and their defects can lead to a series of neurodegenerative diseases. This review will discuss the structure and functions of vesicle-based synapses and their roles in neurons. Furthermore, we will analyze neurotransmitter and synaptic functions in neurodegenerative diseases and discuss the potential of using related drugs in their treatment.
Collapse
|
5
|
Cervantes González A, Irwin DJ, Alcolea D, McMillan CT, Chen-Plotkin A, Wolk D, Sirisi S, Dols-Icardo O, Querol-Vilaseca M, Illán-Gala I, Santos-Santos MA, Fortea J, Lee EB, Trojanowski JQ, Grossman M, Lleó A, Belbin O. Multimarker synaptic protein cerebrospinal fluid panels reflect TDP-43 pathology and cognitive performance in a pathological cohort of frontotemporal lobar degeneration. Mol Neurodegener 2022; 17:29. [PMID: 35395770 PMCID: PMC8991834 DOI: 10.1186/s13024-022-00534-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 03/30/2022] [Indexed: 12/13/2022] Open
Abstract
Background Synapse degeneration is an early event in pathological frontotemporal lobar degeneration (FTLD). Consequently, a surrogate marker of synapse loss could be used to monitor early pathologic changes in patients with underlying FTLD. The aim of this study was to evaluate the relationship of antemortem cerebrospinal fluid (CSF) levels of 8 synaptic proteins with postmortem global tau and TDP-43 burden and cognitive performance and to assess their diagnostic capacity in a neuropathological FTLD cohort. Methods We included patients with a neuropathological confirmation of FTLD-Tau (n = 24, mean age-at-CSF 67 years ± 11), FTLD-TDP (n = 25, 66 years ± 9) or AD (n = 25, 73 years ± 6) as well as cognitively normal controls (n = 35, 69 years ± 7) from the Penn FTD Center and ADRC. We used a semi-quantitative measure of tau and TDP-43 inclusions to quantify pathological burden across 16 brain regions. Statistical methods included Spearman rank correlations, one-way analysis of covariance, ordinal regression, step-wise multiple linear regression and receiver-operating characteristic curves. Result CSF calsyntenin-1 and neurexin-2a were correlated in all patient groups (rs = .55 to .88). In FTLD-TDP, we observed low antemortem CSF levels of calsyntenin-1 and neurexin-2a compared to AD (.72-fold, p = .001, .77-fold, p = .04, respectively) and controls (.80-fold, p = .02, .78-fold, p = .02, respectively), which were inversely associated with post-mortem global TDP-43 burden (regression r2 = .56, p = .007 and r2 = .57, p = .006, respectively). A multimarker panel including calsyntenin-1 was associated with TDP-43 burden (r2 = .69, p = .003) and MMSE score (r2 = .19, p = .03) in FTLD. A second multimarker synaptic panel, also including calsyntenin-1, was associated with MMSE score in FTLD-tau (r2 = .49, p = .04) and improved diagnostic performance to discriminate FTLD-Tau and FTLD-TDP neuropathologic subtypes (AUC = .83). Conclusion These synaptic panels have potential in the differential diagnosis of FTLD neuropathologic subtypes and as surrogate markers of cognitive performance in future clinical trials targeting TDP-43 or tau. Supplementary Information The online version contains supplementary material available at 10.1186/s13024-022-00534-y.
Collapse
Affiliation(s)
- Alba Cervantes González
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - David J Irwin
- Penn FTD Center, Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Daniel Alcolea
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Corey T McMillan
- Penn FTD Center, Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Alice Chen-Plotkin
- Penn Alzheimer's Disease Research Center, Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - David Wolk
- Penn Alzheimer's Disease Research Center, Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Sònia Sirisi
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Oriol Dols-Icardo
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Marta Querol-Vilaseca
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Ignacio Illán-Gala
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Miguel Angel Santos-Santos
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Juan Fortea
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Edward B Lee
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - John Q Trojanowski
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Murray Grossman
- Penn FTD Center, Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Alberto Lleó
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain
| | - Olivia Belbin
- Hospital de La Santa Creu I Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain. .,Centre of Biomedical Investigation Network for Neurodegenerative Diseases (CIBERNED), Madrid, Spain. .,Memory Unit and Biomedical Research Institute, IIB Sant Pau, c/Sant Quintí 77, 08041, Barcelona, Spain.
| |
Collapse
|
6
|
Plooster M, Rossi G, Farrell MS, McAfee JC, Bell JL, Ye M, Diering GH, Won H, Gupton SL, Brennwald P. Schizophrenia-Linked Protein tSNARE1 Regulates Endosomal Trafficking in Cortical Neurons. J Neurosci 2021; 41:9466-9481. [PMID: 34642214 PMCID: PMC8580139 DOI: 10.1523/jneurosci.0556-21.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 10/04/2021] [Accepted: 10/04/2021] [Indexed: 12/13/2022] Open
Abstract
TSNARE1, which encodes the protein tSNARE1, is a high-confidence gene candidate for schizophrenia risk, but nothing is known about its cellular or physiological function. We identified the major gene products of TSNARE1 and their cytoplasmic localization and function in endosomal trafficking in cortical neurons. We validated three primary isoforms of TSNARE1 expressed in human brain, all of which encode a syntaxin-like Qa SNARE domain. RNA-sequencing data from adult and fetal human brain suggested that the majority of tSNARE1 lacks a transmembrane domain that is thought to be necessary for membrane fusion. Biochemical data demonstrate that tSNARE1 can compete with Stx12 for incorporation into an endosomal SNARE complex, supporting its possible role as an inhibitory SNARE. Live-cell imaging in cortical neurons from mice of both sexes demonstrated that brain tSNARE1 isoforms localized to the endosomal network. The most abundant brain isoform, tSNARE1c, localized most frequently to Rab7+ late endosomes, and endogenous tSNARE1 displayed a similar localization in human neural progenitor cells and neuroblastoma cells. In mature rat neurons from both sexes, tSNARE1 localized to the dendritic shaft and dendritic spines, supporting a role for tSNARE1 at the postsynapse. Expression of either tSNARE1b or tSNARE1c, which differ only in their inclusion or exclusion of an Myb-like domain, delayed the trafficking of the dendritic endosomal cargo Nsg1 into late endosomal and lysosomal compartments. These data suggest that tSNARE1 regulates endosomal trafficking in cortical neurons, likely by negatively regulating early endosomal to late endosomal trafficking.SIGNIFICANCE STATEMENT Schizophrenia is a severe and polygenic neuropsychiatric disorder. Understanding the functions of high-confidence candidate genes is critical toward understanding how their dysfunction contributes to schizophrenia pathogenesis. TSNARE1 is one of the high-confidence candidate genes for schizophrenia risk, yet nothing was known about its cellular or physiological function. Here we describe the major isoforms of TSNARE1 and their cytoplasmic localization and function in the endosomal network in cortical neurons. Our results are consistent with the hypothesis that the majority of brain tSNARE1 acts as a negative regulator to endolysosomal trafficking.
Collapse
Affiliation(s)
- Melissa Plooster
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Guendalina Rossi
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Martilias S Farrell
- Department of Genetics, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Jessica C McAfee
- Department of Genetics, University of North Carolina, Chapel Hill, North Carolina 27599
- UNC Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Jessica L Bell
- Department of Genetics, University of North Carolina, Chapel Hill, North Carolina 27599
- UNC Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Michael Ye
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Graham H Diering
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina 27599
- UNC Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina 27599
- Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Hyejung Won
- Department of Genetics, University of North Carolina, Chapel Hill, North Carolina 27599
- UNC Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Stephanie L Gupton
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina 27599
- UNC Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina 27599
- Lineberger Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Patrick Brennwald
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina 27599
| |
Collapse
|
7
|
Lleó A, Carmona-Iragui M, Videla L, Fernández S, Benejam B, Pegueroles J, Barroeta I, Altuna M, Valldeneu S, Xiao MF, Xu D, Núñez-Llaves R, Querol-Vilaseca M, Sirisi S, Bejanin A, Iulita MF, Clarimón J, Blesa R, Worley P, Alcolea D, Fortea J, Belbin O. VAMP-2 is a surrogate cerebrospinal fluid marker of Alzheimer-related cognitive impairment in adults with Down syndrome. Alzheimers Res Ther 2021; 13:119. [PMID: 34183050 PMCID: PMC8240298 DOI: 10.1186/s13195-021-00861-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 06/14/2021] [Indexed: 02/08/2023]
Abstract
BACKGROUND There is an urgent need for objective markers of Alzheimer's disease (AD)-related cognitive impairment in people with Down syndrome (DS) to improve diagnosis, monitor disease progression, and assess response to disease-modifying therapies. Previously, GluA4 and neuronal pentraxin 2 (NPTX2) showed limited potential as cerebrospinal fluid (CSF) markers of cognitive impairment in adults with DS. Here, we compare the CSF profile of a panel of synaptic proteins (Calsyntenin-1, Neuroligin-2, Neurexin-2A, Neurexin-3A, Syntaxin-1B, Thy-1, VAMP-2) to that of NPTX2 and GluA4 in a large cohort of subjects with DS across the preclinical and clinical AD continuum and explore their correlation with cognitive impairment. METHODS We quantified the synaptic panel proteins by selected reaction monitoring in CSF from 20 non-trisomic cognitively normal controls (mean age 44) and 80 adults with DS grouped according to clinical AD diagnosis (asymptomatic, prodromal AD or AD dementia). We used regression analyses to determine CSF changes across the AD continuum and explored correlations with age, global cognitive performance (CAMCOG), episodic memory (modified cued-recall test; mCRT) and CSF biomarkers, CSF Aβ42:40 ratio, CSF Aβ1-42, CSF p-tau, and CSF NFL. P values were adjusted for multiple testing. RESULTS In adults with DS, VAMP-2 was the only synaptic protein to correlate with episodic memory (delayed recall adj.p = .04) and age (adj.p = .0008) and was the best correlate of CSF Aβ42:40 (adj.p = .0001), p-tau (adj.p < .0001), and NFL (adj.p < .0001). Compared to controls, mean VAMP-2 levels were lower in asymptomatic adults with DS only (adj.p = .02). CSF levels of Neurexin-3A, Thy-1, Neurexin-2A, Calysntenin-1, Neuroligin-2, GluA4, and Syntaxin-1B all strongly correlated with NPTX2 (p < .0001), which was the only synaptic protein to show reduced CSF levels in DS at all AD stages compared to controls (adj.p < .002). CONCLUSION These data show proof-of-concept for CSF VAMP-2 as a potential marker of synapse degeneration that correlates with CSF AD and axonal degeneration markers and cognitive performance.
Collapse
Affiliation(s)
- Alberto Lleó
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Maria Carmona-Iragui
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
- Barcelona Down Medical Center, Fundació Catalana Síndrome de Down, Barcelona, Spain
| | - Laura Videla
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
- Barcelona Down Medical Center, Fundació Catalana Síndrome de Down, Barcelona, Spain
| | - Susana Fernández
- Barcelona Down Medical Center, Fundació Catalana Síndrome de Down, Barcelona, Spain
| | - Bessy Benejam
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Barcelona Down Medical Center, Fundació Catalana Síndrome de Down, Barcelona, Spain
| | - Jordi Pegueroles
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Isabel Barroeta
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Miren Altuna
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Silvia Valldeneu
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Mei-Fang Xiao
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Desheng Xu
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Raúl Núñez-Llaves
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Marta Querol-Vilaseca
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Sònia Sirisi
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Alexandre Bejanin
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - M Florencia Iulita
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
| | - Jordi Clarimón
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Rafael Blesa
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Paul Worley
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Daniel Alcolea
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Juan Fortea
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Olivia Belbin
- Memory Unit and Biomedical Research Institute Sant Pau (IIB Sant Pau), Neurology Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, c/Sant Quintí, 77-79, 08025, Barcelona, Spain.
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain.
| |
Collapse
|
8
|
Extreme parsimony in ATP consumption by 20S complexes in the global disassembly of single SNARE complexes. Nat Commun 2021; 12:3206. [PMID: 34050166 PMCID: PMC8163800 DOI: 10.1038/s41467-021-23530-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 04/30/2021] [Indexed: 11/08/2022] Open
Abstract
Fueled by ATP hydrolysis in N-ethylmaleimide sensitive factor (NSF), the 20S complex disassembles rigid SNARE (soluble NSF attachment protein receptor) complexes in single unraveling step. This global disassembly distinguishes NSF from other molecular motors that make incremental and processive motions, but the molecular underpinnings of its remarkable energy efficiency remain largely unknown. Using multiple single-molecule methods, we found remarkable cooperativity in mechanical connection between NSF and the SNARE complex, which prevents dysfunctional 20S complexes that consume ATP without productive disassembly. We also constructed ATP hydrolysis cycle of the 20S complex, in which NSF largely shows randomness in ATP binding but switches to perfect ATP hydrolysis synchronization to induce global SNARE disassembly, minimizing ATP hydrolysis by non-20S complex-forming NSF molecules. These two mechanisms work in concert to concentrate ATP consumption into functional 20S complexes, suggesting evolutionary adaptations by the 20S complex to the energetically expensive mechanical task of SNARE complex disassembly. Fueled by ATP hydrolysis in N-ethylmaleimide sensitive factor (NSF), the 20S complex disassembles SNARE complexes in a single unravelling step. Here authors use single-molecule methods to show cooperativity between the NSF and SNARE complex, which prevents ATP consumption without productive disassembly.
Collapse
|
9
|
Göhde R, Naumann B, Laundon D, Imig C, McDonald K, Cooper BH, Varoqueaux F, Fasshauer D, Burkhardt P. Choanoflagellates and the ancestry of neurosecretory vesicles. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190759. [PMID: 33550951 PMCID: PMC7934909 DOI: 10.1098/rstb.2019.0759] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2020] [Indexed: 01/08/2023] Open
Abstract
Neurosecretory vesicles are highly specialized trafficking organelles that store neurotransmitters that are released at presynaptic nerve endings and are, therefore, important for animal cell-cell signalling. Despite considerable anatomical and functional diversity of neurons in animals, the protein composition of neurosecretory vesicles in bilaterians appears to be similar. This similarity points towards a common evolutionary origin. Moreover, many putative homologues of key neurosecretory vesicle proteins predate the origin of the first neurons, and some even the origin of the first animals. However, little is known about the molecular toolkit of these vesicles in non-bilaterian animals and their closest unicellular relatives, making inferences about the evolutionary origin of neurosecretory vesicles extremely difficult. By comparing 28 proteins of the core neurosecretory vesicle proteome in 13 different species, we demonstrate that most of the proteins are present in unicellular organisms. Surprisingly, we find that the vesicular membrane-associated soluble N-ethylmaleimide-sensitive factor attachment protein receptor protein synaptobrevin is localized to the vesicle-rich apical and basal pole in the choanoflagellate Salpingoeca rosetta. Our 3D vesicle reconstructions reveal that the choanoflagellates S. rosetta and Monosiga brevicollis exhibit a polarized and diverse vesicular landscape reminiscent of the polarized organization of chemical synapses that secrete the content of neurosecretory vesicles into the synaptic cleft. This study sheds light on the ancestral molecular machinery of neurosecretory vesicles and provides a framework to understand the origin and evolution of secretory cells, synapses and neurons. This article is part of the theme issue 'Basal cognition: multicellularity, neurons and the cognitive lens'.
Collapse
Affiliation(s)
- Ronja Göhde
- Sars International Centre for Molecular Marine Biology, University of Bergen, 5006 Bergen, Norway
| | - Benjamin Naumann
- Institute of Zoology and Evolutionary Research, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Davis Laundon
- Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
| | - Cordelia Imig
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Gottingen, Germany
| | - Kent McDonald
- Electron Microscope Laboratory, University of California, Berkeley, CA 94720, USA
| | - Benjamin H. Cooper
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Gottingen, Germany
| | - Frédérique Varoqueaux
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
| | - Dirk Fasshauer
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
| | - Pawel Burkhardt
- Sars International Centre for Molecular Marine Biology, University of Bergen, 5006 Bergen, Norway
| |
Collapse
|
10
|
Mühlenbrock P, Sari M, Steinem C. In vitro single vesicle fusion assays based on pore-spanning membranes: merits and drawbacks. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2021; 50:239-252. [PMID: 33320298 PMCID: PMC8071798 DOI: 10.1007/s00249-020-01479-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 11/06/2020] [Accepted: 11/09/2020] [Indexed: 12/22/2022]
Abstract
Neuronal fusion mediated by soluble N-ethylmaleimide-sensitive-factor attachment protein receptors (SNAREs) is a fundamental cellular process by which two initially distinct membranes merge resulting in one interconnected structure to release neurotransmitters into the presynaptic cleft. To get access to the different stages of the fusion process, several in vitro assays have been developed. In this review, we provide a short overview of the current in vitro single vesicle fusion assays. Among those assays, we developed a single vesicle assay based on pore-spanning membranes (PSMs) on micrometre-sized pores in silicon, which might overcome some of the drawbacks associated with the other membrane architectures used for investigating fusion processes. Prepared by spreading of giant unilamellar vesicles with reconstituted t-SNAREs, PSMs provide an alternative tool to supported lipid bilayers to measure single vesicle fusion events by means of fluorescence microscopy. Here, we discuss the diffusive behaviour of the reconstituted membrane components as well as that of the fusing synthetic vesicles with reconstituted synaptobrevin 2 (v-SNARE). We compare our results with those obtained if the synthetic vesicles are replaced by natural chromaffin granules under otherwise identical conditions. The fusion efficiency as well as the different fusion states observable in this assay by means of both lipid mixing and content release are illuminated.
Collapse
Affiliation(s)
- Peter Mühlenbrock
- Georg-August-Universität Göttingen, Institute of Organic and Biomolecular Chemistry, Tammannstr. 2, 37077, Göttingen, Germany
| | - Merve Sari
- Georg-August-Universität Göttingen, Institute of Organic and Biomolecular Chemistry, Tammannstr. 2, 37077, Göttingen, Germany
| | - Claudia Steinem
- Georg-August-Universität Göttingen, Institute of Organic and Biomolecular Chemistry, Tammannstr. 2, 37077, Göttingen, Germany.
- Max-Planck-Institute for Dynamics and Self Organization, Am Faßberg 17, 37077, Göttingen, Germany.
| |
Collapse
|
11
|
Yang Y, Margam NN. Structural Insights into Membrane Fusion Mediated by Convergent Small Fusogens. Cells 2021; 10:cells10010160. [PMID: 33467484 PMCID: PMC7830690 DOI: 10.3390/cells10010160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 01/07/2021] [Accepted: 01/13/2021] [Indexed: 12/30/2022] Open
Abstract
From lifeless viral particles to complex multicellular organisms, membrane fusion is inarguably the important fundamental biological phenomena. Sitting at the heart of membrane fusion are protein mediators known as fusogens. Despite the extensive functional and structural characterization of these proteins in recent years, scientists are still grappling with the fundamental mechanisms underlying membrane fusion. From an evolutionary perspective, fusogens follow divergent evolutionary principles in that they are functionally independent and do not share any sequence identity; however, they possess structural similarity, raising the possibility that membrane fusion is mediated by essential motifs ubiquitous to all. In this review, we particularly emphasize structural characteristics of small-molecular-weight fusogens in the hope of uncovering the most fundamental aspects mediating membrane–membrane interactions. By identifying and elucidating fusion-dependent functional domains, this review paves the way for future research exploring novel fusogens in health and disease.
Collapse
|
12
|
Wilhelmi I, Grunwald S, Gimber N, Popp O, Dittmar G, Arumughan A, Wanker EE, Laeger T, Schmoranzer J, Daumke O, Schürmann A. The ARFRP1-dependent Golgi scaffolding protein GOPC is required for insulin secretion from pancreatic β-cells. Mol Metab 2020; 45:101151. [PMID: 33359402 PMCID: PMC7811047 DOI: 10.1016/j.molmet.2020.101151] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 12/15/2020] [Accepted: 12/15/2020] [Indexed: 12/13/2022] Open
Abstract
Objective Hormone secretion from metabolically active tissues, such as pancreatic islets, is governed by specific and highly regulated signaling pathways. Defects in insulin secretion are among the major causes of diabetes. The molecular mechanisms underlying regulated insulin secretion are, however, not yet completely understood. In this work, we studied the role of the GTPase ARFRP1 on insulin secretion from pancreatic β-cells. Methods A β-cell-specific Arfrp1 knockout mouse was phenotypically characterized. Pulldown experiments and mass spectrometry analysis were employed to screen for new ARFRP1-interacting proteins. Co-immunoprecipitation assays as well as super-resolution microscopy were applied for validation. Results The GTPase ARFRP1 interacts with the Golgi-associated PDZ and coiled-coil motif-containing protein (GOPC). Both proteins are co-localized at the trans-Golgi network and regulate the first and second phase of insulin secretion by controlling the plasma membrane localization of the SNARE protein SNAP25. Downregulation of both GOPC and ARFRP1 in Min6 cells interferes with the plasma membrane localization of SNAP25 and enhances its degradation, thereby impairing glucose-stimulated insulin release from β-cells. In turn, overexpression of SNAP25 as well as GOPC restores insulin secretion in islets from β-cell-specific Arfrp1 knockout mice. Conclusion Our results identify a hitherto unrecognized pathway required for insulin secretion at the level of trans-Golgi sorting. β-cell specific deletion of the trans-Golgi residing small GTPase ARFRP1 leads to elevated blood glucose levels in mice. GOPC is a newly identified ARFRP1 dependent scaffolding protein. ARFRP1 and GOPC are required for glucose-stimulated insulin secretion from pancreatic β-cells.
Collapse
Affiliation(s)
- Ilka Wilhelmi
- German Institute of Human Nutrition (DIfE) Potsdam-Rehbruecke, Germany; German Center for Diabetes Research (DZD) Munich Neuherberg, Germany
| | - Stephan Grunwald
- Max-Delbrück Center for Molecular Medicine in the Helmholtz Association Berlin, Germany; Institute of Chemistry and Biochemistry, Freie Universität Berlin, Germany
| | - Niclas Gimber
- Advanced Medical Bioimaging Core Facility - AMBIO, Charité-Universitätsmedizin Berlin, Germany
| | - Oliver Popp
- Max-Delbrück Center for Molecular Medicine in the Helmholtz Association Berlin, Germany
| | - Gunnar Dittmar
- Max-Delbrück Center for Molecular Medicine in the Helmholtz Association Berlin, Germany
| | - Anup Arumughan
- Neuroproteomics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC) Berlin, Germany
| | - Erich E Wanker
- Neuroproteomics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC) Berlin, Germany
| | - Thomas Laeger
- German Institute of Human Nutrition (DIfE) Potsdam-Rehbruecke, Germany; German Center for Diabetes Research (DZD) Munich Neuherberg, Germany
| | - Jan Schmoranzer
- Advanced Medical Bioimaging Core Facility - AMBIO, Charité-Universitätsmedizin Berlin, Germany
| | - Oliver Daumke
- Max-Delbrück Center for Molecular Medicine in the Helmholtz Association Berlin, Germany; Institute of Chemistry and Biochemistry, Freie Universität Berlin, Germany
| | - Annette Schürmann
- German Institute of Human Nutrition (DIfE) Potsdam-Rehbruecke, Germany; German Center for Diabetes Research (DZD) Munich Neuherberg, Germany; University of Potsdam, Institute of Nutritional Sciences, Nuthetal, Germany; Faculty of Health Sciences, Joint Faculty of the Brandenburg University of Technology Cottbus - Senftenberg, the Brandenburg Medical School Theodor Fontane and the University of Potsdam, Germany.
| |
Collapse
|
13
|
Zhang H, Yan H, Shim WB. Fusarium verticillioides SNARE protein FvSyn1 harbours two key functional motifs that play selective roles in fungal development and virulence. MICROBIOLOGY-SGM 2019; 165:1075-1085. [PMID: 31390325 DOI: 10.1099/mic.0.000843] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Fusarium verticillioides is one of the key fungal pathogens responsible for maize stalk rot. While stalk rot pathogens are prevalent worldwide, our understanding of the stalk rot virulence mechanism in pathogenic fungi is still very limited. We previously identified the F. verticillioides FvSYN1 gene, which was demonstrated to play an important role in maize stalk rot virulence. FvSyn1 belongs to a family of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins that play critical roles in a variety of developmental processes. In this study, we further characterized the cellular features of the FvSyn1 protein, namely how different motifs contribute to development and virulence in F. verticillioides by generating motif-specific deletion mutants. Microscopic observation showed that the ∆Fvsyn1 mutant exhibits rough and hyper-branched hyphae when compared to the wild-type progenitor. Moreover, the ∆Fvsyn1 mutant was sensitive to cell wall stress agents, resulting in vegetative growth reduction. We showed that the FvSyn1::GFP protein is associated with the endomembrane, but this did not clarify why the deletion of FvSyn1 led to stress sensitivity and aberrant hyphal development. Characterization of the FvSyn1 domains indicated that both the syntaxin N-terminus (SynN) domain and the SNARE C-terminus domain play distinct roles in fungal development, but also function collectively in the context of virulence. We also determined that two domains in FvSyn1 are not required for fumonisin production. Interestingly, these two domains were involved in carbon nutrient utilization, including pectin, starch and sorbitol. This study further characterized the role of FvSyn1 domains in hyphal growth, cell wall stress response and virulence in F. verticillioides.
Collapse
Affiliation(s)
- Huan Zhang
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA
| | - Huijuan Yan
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA
| | - Won Bo Shim
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA
| |
Collapse
|
14
|
Cardenas EI, Gonzalez R, Breaux K, Da Q, Gutierrez BA, Ramos MA, Cardenas RA, Burns AR, Rumbaut RE, Adachi R. Munc18-2, but not Munc18-1 or Munc18-3, regulates platelet exocytosis, hemostasis, and thrombosis. J Biol Chem 2019; 294:4784-4792. [PMID: 30696774 DOI: 10.1074/jbc.ra118.006922] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/24/2019] [Indexed: 12/17/2022] Open
Abstract
Platelet degranulation, a form of regulated exocytosis, is crucial for hemostasis and thrombosis. Exocytosis in platelets is mediated by SNARE proteins, and in most mammalian cells this process is controlled by Munc18 (mammalian homolog of Caenorhabditis elegans uncoordinated gene 18) proteins. Platelets express all Munc18 paralogs (Munc18-1, -2, and -3), but their roles in platelet secretion and function have not been fully characterized. Using Munc18-1, -2, and -3 conditional knockout mice, here we deleted expression of these proteins in platelets and assessed granule exocytosis. We measured products secreted by each type of platelet granule and analyzed EM platelet profiles by design-based stereology. We observed that the removal of Munc18-2 ablates the release of alpha, dense, and lysosomal granules from platelets, but we found no exocytic role for Munc18-1 or -3 in platelets. In vitro, Munc18-2-deficient platelets exhibited defective aggregation at low doses of collagen and impaired thrombus formation under shear stress. In vivo, megakaryocyte-specific Munc18-2 conditional knockout mice had a severe hemostatic defect and prolonged arterial and venous bleeding times. They were also protected against arterial thrombosis in a chemically induced model of arterial injury. Taken together, our results indicate that Munc18-2, but not Munc18-1 or Munc18-3, is essential for regulated exocytosis in platelets and platelet participation in thrombosis and hemostasis.
Collapse
Affiliation(s)
- Eduardo I Cardenas
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030.,the Escuela de Ingenieria y Ciencias, Instituto Tecnologico de Monterrey, Monterrey, Nuevo Leon 64849, Mexico
| | - Ricardo Gonzalez
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030.,the Escuela de Ingenieria y Ciencias, Instituto Tecnologico de Monterrey, Monterrey, Nuevo Leon 64849, Mexico
| | - Keegan Breaux
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Qi Da
- the Center for Translational Research on Inflammatory Diseases (CTRID), Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas 77030.,the Department of Medicine, Baylor College of Medicine, Houston, Texas 77030
| | - Berenice A Gutierrez
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030.,the Escuela de Ingenieria y Ciencias, Instituto Tecnologico de Monterrey, Monterrey, Nuevo Leon 64849, Mexico
| | - Marco A Ramos
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Rodolfo A Cardenas
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030.,the Escuela de Medicina y Ciencias de la Salud, Instituto Tecnologico de Monterrey, Monterrey, Nuevo León 64710, México, and
| | - Alan R Burns
- the College of Optometry, University of Houston, Houston, Texas 77204
| | - Rolando E Rumbaut
- the Center for Translational Research on Inflammatory Diseases (CTRID), Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas 77030.,the Department of Medicine, Baylor College of Medicine, Houston, Texas 77030
| | - Roberto Adachi
- From the Department of Pulmonary Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030,
| |
Collapse
|
15
|
Dynamic Light Scattering Analysis to Dissect Intermediates of SNARE-Mediated Membrane Fusion. Methods Mol Biol 2018. [PMID: 30317498 DOI: 10.1007/978-1-4939-8760-3_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Dynamic light scattering (DLS) spectroscopy provides rapid information on the size distribution of a large number of particles in a mixture. Vesicle sizes change during the merger of lipid bilayers, and DLS analysis can provide rapid, accurate, and non-perturbative quantification of the size distribution of proteoliposomes in SNARE-dependent membrane fusion. In this chapter, we describe the methodologies and reagents used for DLS spectroscopy in a biochemical and biophysical study of SNARE-mediated membrane fusion.
Collapse
|
16
|
Naslavsky N, Caplan S. The enigmatic endosome - sorting the ins and outs of endocytic trafficking. J Cell Sci 2018; 131:131/13/jcs216499. [PMID: 29980602 DOI: 10.1242/jcs.216499] [Citation(s) in RCA: 199] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The early endosome (EE), also known as the sorting endosome (SE) is a crucial station for the sorting of cargoes, such as receptors and lipids, through the endocytic pathways. The term endosome relates to the receptacle-like nature of this organelle, to which endocytosed cargoes are funneled upon internalization from the plasma membrane. Having been delivered by the fusion of internalized vesicles with the EE or SE, cargo molecules are then sorted to a variety of endocytic pathways, including the endo-lysosomal pathway for degradation, direct or rapid recycling to the plasma membrane, and to a slower recycling pathway that involves a specialized form of endosome known as a recycling endosome (RE), often localized to the perinuclear endocytic recycling compartment (ERC). It is striking that 'the endosome', which plays such essential cellular roles, has managed to avoid a precise description, and its characteristics remain ambiguous and heterogeneous. Moreover, despite the rapid advances in scientific methodologies, including breakthroughs in light microscopy, overall, the endosome remains poorly defined. This Review will attempt to collate key characteristics of the different types of endosomes and provide a platform for discussion of this unique and fascinating collection of organelles. Moreover, under-developed, poorly understood and important open questions will be discussed.
Collapse
Affiliation(s)
- Naava Naslavsky
- The Department of Biochemistry and Molecular Biology, The University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Steve Caplan
- The Department of Biochemistry and Molecular Biology, The University of Nebraska Medical Center, Omaha, NE 68198, USA .,The Fred and Pamela Buffett Cancer Center, The University of Nebraska Medical Center, Omaha, NE 68198, USA
| |
Collapse
|
17
|
Gutierrez BA, Chavez MA, Rodarte AI, Ramos MA, Dominguez A, Petrova Y, Davalos AJ, Costa RM, Elizondo R, Tuvim MJ, Dickey BF, Burns AR, Heidelberger R, Adachi R. Munc18-2, but not Munc18-1 or Munc18-3, controls compound and single-vesicle-regulated exocytosis in mast cells. J Biol Chem 2018; 293:7148-7159. [PMID: 29599294 DOI: 10.1074/jbc.ra118.002455] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 03/20/2018] [Indexed: 11/06/2022] Open
Abstract
Mast cells (MCs) play pivotal roles in many inflammatory conditions including infections, anaphylaxis, and asthma. MCs store immunoregulatory compounds in their large cytoplasmic granules and, upon stimulation, secrete them via regulated exocytosis. Exocytosis in many cells requires the participation of Munc18 proteins (also known as syntaxin-binding proteins), and we found that mature MCs express all three mammalian isoforms: Munc18-1, -2, and -3. To study their functions in MC effector responses and test the role of MC degranulation in anaphylaxis, we used conditional knockout (cKO) mice in which each Munc18 protein was deleted exclusively in MCs. Using recordings of plasma membrane capacitance for high-resolution analysis of exocytosis in individual MCs, we observed an almost complete absence of exocytosis in Munc18-2-deficient MCs but intact exocytosis in MCs lacking Munc18-1 or Munc18-3. Stereological analysis of EM images of stimulated MCs revealed that the deletion of Munc18-2 also abolishes the homotypic membrane fusion required for compound exocytosis. We confirmed the severe defect in regulated exocytosis in the absence of Munc18-2 by measuring the secretion of mediators stored in MC granules. Munc18-2 cKO mice had normal morphology, development, and distribution of their MCs, indicating that Munc18-2 is not essential for the migration, retention, and maturation of MC-committed progenitors. Despite that, we found that Munc18-2 cKO mice were significantly protected from anaphylaxis. In conclusion, MC-regulated exocytosis is required for the anaphylactic response, and Munc18-2 is the sole Munc18 isoform that mediates membrane fusion during MC degranulation.
Collapse
Affiliation(s)
- Berenice A Gutierrez
- Department of Pulmonary Medicine, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030; Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Monterrey NL 64849 México
| | - Miguel A Chavez
- Department of Pulmonary Medicine, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030; Escuela de Medicina y Ciencias de la Salud, Tecnologico de Monterrey, Monterrey NL 64710 México
| | - Alejandro I Rodarte
- Department of Pulmonary Medicine, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030; Escuela de Medicina y Ciencias de la Salud, Tecnologico de Monterrey, Monterrey NL 64710 México
| | - Marco A Ramos
- Department of Pulmonary Medicine, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Andrea Dominguez
- Escuela de Medicina y Ciencias de la Salud, Tecnologico de Monterrey, Monterrey NL 64710 México
| | - Youlia Petrova
- Department of Pulmonary Medicine, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Alfredo J Davalos
- Department of Pulmonary Medicine, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Renan M Costa
- Graduate School of Biomedical Sciences, Houston, Texas 77030
| | - Ramon Elizondo
- Escuela de Medicina y Ciencias de la Salud, Tecnologico de Monterrey, Monterrey NL 64710 México
| | - Michael J Tuvim
- Department of Pulmonary Medicine, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Burton F Dickey
- Department of Pulmonary Medicine, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Alan R Burns
- College of Optometry, University of Houston, Houston, Texas 77204
| | - Ruth Heidelberger
- Department of Neurobiology and Anatomy, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030
| | - Roberto Adachi
- Department of Pulmonary Medicine, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030.
| |
Collapse
|
18
|
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: 9] [Impact Index Per Article: 1.3] [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.
Collapse
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.
| |
Collapse
|
19
|
Molecular regulation of insulin granule biogenesis and exocytosis. Biochem J 2017; 473:2737-56. [PMID: 27621482 DOI: 10.1042/bcj20160291] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 04/19/2016] [Indexed: 12/15/2022]
Abstract
Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by hyperglycemia, insulin resistance and hyperinsulinemia in early disease stages but a relative insulin insufficiency in later stages. Insulin, a peptide hormone, is produced in and secreted from pancreatic β-cells following elevated blood glucose levels. Upon its release, insulin induces the removal of excessive exogenous glucose from the bloodstream primarily by stimulating glucose uptake into insulin-dependent tissues as well as promoting hepatic glycogenesis. Given the increasing prevalence of T2DM worldwide, elucidating the underlying mechanisms and identifying the various players involved in the synthesis and exocytosis of insulin from β-cells is of utmost importance. This review summarizes our current understanding of the route insulin takes through the cell after its synthesis in the endoplasmic reticulum as well as our knowledge of the highly elaborate network that controls insulin release from the β-cell. This network harbors potential targets for anti-diabetic drugs and is regulated by signaling cascades from several endocrine systems.
Collapse
|
20
|
Yin DT, Xu J, Lei M, Li H, Wang Y, Liu Z, Zhou Y, Xing M. Characterization of the novel tumor-suppressor gene CCDC67 in papillary thyroid carcinoma. Oncotarget 2016; 7:5830-41. [PMID: 26716505 PMCID: PMC4868724 DOI: 10.18632/oncotarget.6709] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 11/25/2015] [Indexed: 02/07/2023] Open
Abstract
Background Some studies showed an association of coiled-coil domain-containing (CCDC) genes with cancers. Our previous limited data specifically suggested a possible pathogenic role of CCDC67 in papillary thyroid cancer (PTC), but this has not been firmly established. The present study was to further investigate and establish this role of CCDC67 in PTC. Results The expression of CCDC67, both at mRNA and protein levels, was sharply down-regulated in PTC compared with normal thyroid tissues. Lower CCDC67 expression was significantly associated with aggressive tumor behaviors, such as advanced tumor stages and lymph node metastasis, as well as BRAF mutation. Introduced expression of CCDC67 in TPC-1 cells robustly inhibited cell proliferation, colony formation and migration, induced G1 phase cell cycle arrest, and increased cell apoptosis. Methods Primary PTC tumors and matched normal thyroid tissues were obtained from 200 unselected patients at the initial surgery for detection of CCDC67 mRNA and protein by RT-PCR and Western blotting analyses, respectively. Genomic DNA sequencing was performed to detect BRAF mutation in PTC tumors. Clinicopathological data were retrospectively reviewed for correlation analyses. PTC cell line TPC-1 with stable transfection of CCDC67 was used to investigate the functions of CCDC67. Conclusions This large study demonstrates down-regulation of CCDC67 in PTC, an inverse relationship between CCDC67 expression and PTC aggressiveness and BRAF mutation, and a robust inhibitory effect of CCDC67 on PTC cellular activities. These results are consistent with CCDC67 being a novel and impaired tumor suppressor gene in PTC, providing important prognostic and therapeutic implications for this cancer.
Collapse
Affiliation(s)
- De Tao Yin
- Department of Thyroid Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P. R. China.,Key Discipline Laboratory of Clinical Medicine Henan, Zhengzhou 450052, P. R. China
| | - Jianhui Xu
- Department of Thyroid Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P. R. China.,Key Discipline Laboratory of Clinical Medicine Henan, Zhengzhou 450052, P. R. China
| | - Mengyuan Lei
- Department of Thyroid Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P. R. China.,Key Discipline Laboratory of Clinical Medicine Henan, Zhengzhou 450052, P. R. China
| | - Hongqiang Li
- Department of Thyroid Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P. R. China.,Key Discipline Laboratory of Clinical Medicine Henan, Zhengzhou 450052, P. R. China
| | - Yongfei Wang
- Department of Thyroid Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P. R. China.,Key Discipline Laboratory of Clinical Medicine Henan, Zhengzhou 450052, P. R. China
| | - Zhen Liu
- Department of Thyroid Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P. R. China.,Key Discipline Laboratory of Clinical Medicine Henan, Zhengzhou 450052, P. R. China
| | - Yubing Zhou
- Department of Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P. R. China
| | - Mingzhao Xing
- Division of Endocrinology and Metabolism, the Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| |
Collapse
|
21
|
Abstract
SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins are a highly conserved set of membrane-associated proteins that mediate intracellular membrane fusion. Cognate SNAREs from two separate membranes zipper to facilitate membrane apposition and fusion. Though the stable post-fusion conformation of SNARE complex has been extensively studied with biochemical and biophysical means, the pathway of SNARE zippering has been elusive. In this review, we describe some recent progress in understanding the pathway of SNARE zippering. We particularly focus on the half-zippered intermediate, which is most likely to serve as the main point of regulation by the auxiliary factors.
Collapse
|
22
|
Zheng T, Bulacu M, Daudey G, Versluis F, Voskuhl J, Martelli G, Raap J, Sevink GJA, Kros A, Boyle AL. A non-zipper-like tetrameric coiled coil promotes membrane fusion. RSC Adv 2016. [DOI: 10.1039/c5ra26175a] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A parallel heterodimeric coiled coil can be mutated to an antiparallel tetrameric species by reversing the sequences of one of the peptides. This tetramer is capable of facilitating fast, efficient, membrane fusion of liposomes.
Collapse
Affiliation(s)
- Tingting Zheng
- Supramolecular and Biomaterials Chemistry
- Leiden Institute of Chemistry
- Leiden University
- Leiden
- The Netherlands
| | | | - Geert Daudey
- Supramolecular and Biomaterials Chemistry
- Leiden Institute of Chemistry
- Leiden University
- Leiden
- The Netherlands
| | - Frank Versluis
- Supramolecular and Biomaterials Chemistry
- Leiden Institute of Chemistry
- Leiden University
- Leiden
- The Netherlands
| | - Jens Voskuhl
- Supramolecular and Biomaterials Chemistry
- Leiden Institute of Chemistry
- Leiden University
- Leiden
- The Netherlands
| | - Giuliana Martelli
- Supramolecular and Biomaterials Chemistry
- Leiden Institute of Chemistry
- Leiden University
- Leiden
- The Netherlands
| | - Jan Raap
- Supramolecular and Biomaterials Chemistry
- Leiden Institute of Chemistry
- Leiden University
- Leiden
- The Netherlands
| | - G. J. Agur Sevink
- Solid State NMR
- Leiden Institute of Chemistry
- Leiden University
- Leiden
- The Netherlands
| | - Alexander Kros
- Supramolecular and Biomaterials Chemistry
- Leiden Institute of Chemistry
- Leiden University
- Leiden
- The Netherlands
| | - Aimee L. Boyle
- Supramolecular and Biomaterials Chemistry
- Leiden Institute of Chemistry
- Leiden University
- Leiden
- The Netherlands
| |
Collapse
|
23
|
Yang Y, Heo P, Kong B, Park JB, Jung YH, Shin J, Jeong C, Kweon DH. Dynamic light scattering analysis of SNARE-driven membrane fusion and the effects of SNARE-binding flavonoids. Biochem Biophys Res Commun 2015; 465:864-70. [PMID: 26319432 DOI: 10.1016/j.bbrc.2015.08.111] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 08/25/2015] [Indexed: 01/04/2023]
Abstract
Soluble N-ethylmaleimide-sensitive-factor attachment protein receptor (SNARE) proteins generate energy required for membrane fusion. They form a parallelly aligned four-helix bundle called the SNARE complex, whose formation is initiated from the N terminus and proceeds toward the membrane-proximal C terminus. Previously, we have shown that this zippering-like process can be controlled by several flavonoids that bind to the intermediate structures formed during the SNARE zippering. Here, our aim was to test whether the fluorescence resonance energy transfer signals that are observed during the inner leaflet mixing assay indeed represent the hemifused vesicles. We show that changes in vesicle size accompanying the merging of bilayers is a good measure of progression of the membrane fusion. Two merging vesicles with the same size D in diameter exhibited their hydrodynamic diameters 2D + d (d, intermembrane distance), 2D and 2D as membrane fusion progressed from vesicle docking to hemifusion and full fusion, respectively. A dynamic light scattering assay of membrane fusion suggested that myricetin stopped membrane fusion at the hemifusion state, whereas delphinidin and cyanidin prevented the docking of the vesicles. These results are consistent with our previous findings in fluorescence resonance energy transfer assays.
Collapse
Affiliation(s)
- Yoosoo Yang
- Department of Genetic Engineering and Center for Human Interface Nanotechnology, Sungkyunkwan University, Suwon 440-746, South Korea; Biomedical Research Institute, Korea Institute of Science and Technology, Seoul 136-791, South Korea
| | - Paul Heo
- Department of Genetic Engineering and Center for Human Interface Nanotechnology, Sungkyunkwan University, Suwon 440-746, South Korea
| | - Byoungjae Kong
- Department of Genetic Engineering and Center for Human Interface Nanotechnology, Sungkyunkwan University, Suwon 440-746, South Korea
| | - Jun-Bum Park
- Department of Genetic Engineering and Center for Human Interface Nanotechnology, Sungkyunkwan University, Suwon 440-746, South Korea
| | - Young-Hun Jung
- Department of Genetic Engineering and Center for Human Interface Nanotechnology, Sungkyunkwan University, Suwon 440-746, South Korea
| | - Jonghyeok Shin
- Department of Genetic Engineering and Center for Human Interface Nanotechnology, Sungkyunkwan University, Suwon 440-746, South Korea
| | - Cherlhyun Jeong
- Biomedical Research Institute, Korea Institute of Science and Technology, Seoul 136-791, South Korea
| | - Dae-Hyuk Kweon
- Department of Genetic Engineering and Center for Human Interface Nanotechnology, Sungkyunkwan University, Suwon 440-746, South Korea.
| |
Collapse
|
24
|
|
25
|
Ovsepian SV, Ovespian SV, Bodeker M, O'Leary VB, Lawrence GW, Oliver Dolly J. Internalization and retrograde axonal trafficking of tetanus toxin in motor neurons and trans-synaptic propagation at central synapses exceed those of its C-terminal-binding fragments. Brain Struct Funct 2015; 220:1825-38. [PMID: 25665801 DOI: 10.1007/s00429-015-1004-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 02/04/2015] [Indexed: 12/22/2022]
Abstract
The prominent tropism of tetanus toxin (TeTx) towards peripheral nerves with retrograde transport and transfer to central neurons render it an invaluable probe for exploring fundamental neuronal processes such as endocytosis, retrograde trafficking and trans-synaptic transport to central neurons. While the specificity of TeTx to nerve cells has been attributed to its binding domains (HC and HCC), molecular determinants of the long-range trafficking that ensure its central delivery and induction of spastic paralysis remain elusive. Here, we report that a protease-inactive TeTx mutant (TeTIM) fused to core streptavidin (CS) proved superior to CS-HC and CS-HCC fragments in antagonizing the internalization of the active toxin in cultured spinal cord neurons. Also, in comparison to CS-HC and CS-HCC, CS-TeTIM undergoes faster clearance from motor nerve terminals after peripheral injection, and is detected in a greater number of neurons in the spinal cord and brain stem ipsi-lateral to the administration site. Consistent with trans-synaptic transfer from motor neurons to inter-neurons, CS-TeTIM infiltrated non-cholinergic cells in the spinal cord; in contrast, the retrograde spread of CS-HC was largely restricted to neurons stained for choline acetyltransferase. Peripheral injection of CS-TeTIM conjugated to a lentivirus encoding mutated SNAP-25, resistant to cleavage by botulinum neurotoxin A, E and C1, rendered spontaneous excitatory postsynaptic currents in motor neurons resilient to challenge by type A toxin in vitro, whereas the same virus conjugated to CS-HC proved ineffective. These findings indicate that full-length inactive TeTx greatly exceeds HC and HCC in targeting and invading motor nerve terminals at the periphery and exploits more efficiently the retrograde transport and trans-synaptic transfer mechanisms of motor neurons to arrive at central neurons. Such qualities render TeTIM a more suitable research probe and neuron-targeting vehicle for retro-axonal delivery of viral vectors to the CNS.
Collapse
Affiliation(s)
| | - Saak V Ovespian
- International Centre for Neurotherapeutics, Dublin City University, Dublin 9, Ireland,
| | | | | | | | | |
Collapse
|
26
|
Südhof TC. Der molekulare Mechanismus der Neurotransmitterfreisetzung und Nervenzell-Synapsen (Nobel-Aufsatz). Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201406359] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
27
|
Südhof TC. The molecular machinery of neurotransmitter release (Nobel lecture). Angew Chem Int Ed Engl 2014; 53:12696-717. [PMID: 25339369 DOI: 10.1002/anie.201406359] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Indexed: 12/18/2022]
Abstract
The most important property of synaptic transmission is its speed, which is crucial for the overall workings of the brain. In his Nobel Lecture, T. C. Südhof explains how the synaptic vesicle and the plasma membrane undergo rapid fusion during neurotransmitter release and how this process is spatially organized, such that opening of Ca(2+) -channels allows rapid translation of the entering Ca(2+) signal into a fusion event.
Collapse
Affiliation(s)
- Thomas C Südhof
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Lorry Lokey SIM1 Building 07-535 Room G1021, 265 Campus Drive, Stanford University School of Medicine, CA 94305 (USA)
| |
Collapse
|
28
|
Rajagopalan A, Schweizer N, Nordenankar K, Nilufar Jahan S, Emilsson L, Wallén-Mackenzie Å. Reduced gene expression levels of Munc13-1 and additional components of the presynaptic exocytosis machinery upon conditional targeting of Vglut2 in the adolescent mouse. Synapse 2014; 68:624-633. [PMID: 25139798 DOI: 10.1002/syn.21776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 07/04/2014] [Accepted: 07/11/2014] [Indexed: 11/06/2022]
Abstract
Presynaptic proteins orchestrate an intricate interplay of dynamic interactions in order to regulate quantal exocytosis of transmitter-filled vesicles, and their dysregulation might cause neurological and neuropsychiatric dysfunction. Mice carrying a spatiotemporal restriction in the expression of the Vesicular glutamate transporter 2 (Vglut2; aka Slc17a6) in the cortex, amygdala and hippocampal subiculum from the third postnatal week show a strong anxiolytic phenotype and certain behavioral correlates of schizophrenia. To further understand the molecular consequences of this targeted deletion of Vglut2, we performed an unbiased microarray analysis comparing gene expression levels in the subiculum of these conditional Vglut2 knockout mice (Vglut2f/f;CamKII cKO) to those in control littermates. Expression of Unc13C (Munc13-3), a member of the Unc/Munc family, previously shown to be important for glutamatergic transmission, was identified to be significantly down-regulated. Subsequent analysis by quantitative RT-PCR revealed a 50% down-regulation of Munc 13-1, the gene encoding the Unc/Munc subtype described as an essential component in the majority of glutamtergic synapses in the hippocampus. Genes encoding additional components of the presynaptic machinery were also found regulated, including Rab3A, RIM1α, as well as Syntaxin1 and Synaptobrevin. Altered expression levels of these genes were further found in the amygdala and in the retrosplenial group of the cortex, additional regions in which Vglut2 was conditionally targeted. These findings suggest that expression levels of Vglut2 might be important for the maintenance of gene expression in the presynaptic machinery in the adult mouse brain. Synapse 68:624-633, 2014. © 2014 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Aparna Rajagopalan
- Department of Neuroscience, Units of Functional Neurobiology and Developmental Genetics, Uppsala University, S-752 37, Uppsala, Sweden
| | - Nadine Schweizer
- Department of Neuroscience, Units of Functional Neurobiology and Developmental Genetics, Uppsala University, S-752 37, Uppsala, Sweden
| | - Karin Nordenankar
- Department of Neuroscience, Units of Functional Neurobiology and Developmental Genetics, Uppsala University, S-752 37, Uppsala, Sweden
| | - Sultana Nilufar Jahan
- Department of Neuroscience, Units of Functional Neurobiology and Developmental Genetics, Uppsala University, S-752 37, Uppsala, Sweden
| | - Lina Emilsson
- Department of Neuroscience, Units of Functional Neurobiology and Developmental Genetics, Uppsala University, S-752 37, Uppsala, Sweden.,Department of Organismal Biology, Evolutionary Biology Centre, Uppsala University, S-752 36, Uppsala, Sweden
| | - Åsa Wallén-Mackenzie
- Department of Neuroscience, Units of Functional Neurobiology and Developmental Genetics, Uppsala University, S-752 37, Uppsala, Sweden
| |
Collapse
|
29
|
Acuna C, Guo Q, Burré J, Sharma M, Sun J, Südhof TC. Microsecond dissection of neurotransmitter release: SNARE-complex assembly dictates speed and Ca²⁺ sensitivity. Neuron 2014; 82:1088-100. [PMID: 24908488 DOI: 10.1016/j.neuron.2014.04.020] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2014] [Indexed: 10/25/2022]
Abstract
SNARE-complex assembly mediates synaptic vesicle fusion during neurotransmitter release and requires that the target-SNARE protein syntaxin-1 switches from a closed to an open conformation. Although many SNARE proteins are available per vesicle, only one to three SNARE complexes are minimally needed for a fusion reaction. Here, we use high-resolution measurements of synaptic transmission in the calyx-of-Held synapse from mutant mice in which syntaxin-1 is rendered constitutively open and SNARE-complex assembly is enhanced to examine the relation between SNARE-complex assembly and neurotransmitter release. We show that enhancing SNARE-complex assembly dramatically increases the speed of evoked release, potentiates the Ca(2+)-affinity of release, and accelerates fusion-pore expansion during individual vesicle fusion events. Our data indicate that the number of assembled SNARE complexes per vesicle during fusion determines the presynaptic release probability and fusion kinetics and suggest a mechanism whereby proteins (Munc13 or RIM) may control presynaptic plasticity by regulating SNARE-complex assembly.
Collapse
Affiliation(s)
- Claudio Acuna
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University, 265 Campus Drive, Stanford, CA 94305-5453, USA.
| | - Qingchen Guo
- Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China
| | - Jacqueline Burré
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University, 265 Campus Drive, Stanford, CA 94305-5453, USA
| | - Manu Sharma
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University, 265 Campus Drive, Stanford, CA 94305-5453, USA
| | - Jianyuan Sun
- Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China; Center of Parkinson's Disease, Beijing Institute for Brain Disorders, 15 Datun Road, Chaoyang District, Beijing 100101, China
| | - Thomas C Südhof
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University, 265 Campus Drive, Stanford, CA 94305-5453, USA.
| |
Collapse
|
30
|
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.
Collapse
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:
| |
Collapse
|
31
|
Pantano S, Montecucco C. The blockade of the neurotransmitter release apparatus by botulinum neurotoxins. Cell Mol Life Sci 2014; 71:793-811. [PMID: 23749048 PMCID: PMC11113401 DOI: 10.1007/s00018-013-1380-7] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 05/15/2013] [Accepted: 05/16/2013] [Indexed: 12/22/2022]
Abstract
The high toxicity of the seven serotypes of botulinum neurotoxins (BoNT/A to G), together with their specificity and reversibility, includes them in the list A of potential bioterrorism weapons and, at the same time, among the therapeutics of choice for a variety of human syndromes. They invade nerve terminals and cleave specifically the three proteins which form the heterotrimeric SNAP REceptors (SNARE) complex that mediates neurotransmitter release. The BoNT-induced cleavage of the SNARE proteins explains by itself the paralysing activity of the BoNTs because the truncated proteins cannot form the SNARE complex. However, in the case of BoNT/A, the most widely used toxin in therapy, additional factors come into play as it only removes a few residues from the synaptosomal associate protein of 25 kDa C-terminus and this results in a long duration of action. To explain these facts and other experimental data, we present here a model for the assembly of the neuroexocytosis apparatus in which Synaptotagmin and Complexin first assist the zippering of the SNARE complex, and then stabilize and clamp an octameric radial assembly of the SNARE complexes.
Collapse
Affiliation(s)
- Sergio Pantano
- Institut Pasteur de Montevideo, Calle Mataojo 2020, CP 11400 Montevideo, Uruguay
| | - Cesare Montecucco
- Department of Biomedical Sciences, University of Padova, Padua, Italy
- Institute of Neuroscience, National Research Council, Viale G. Colombo 3, 35121 Padua, Italy
| |
Collapse
|
32
|
Scheller RH. In search of the molecular mechanism of intracellular membrane fusion and neurotransmitter release. Nat Med 2013; 19:1232-5. [PMID: 24100993 DOI: 10.1038/nm.3339] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Richard H Scheller
- Genentech Research and Early Development, 1 DNA Way, San Francisco, California, USA
| |
Collapse
|
33
|
Abstract
Exocytosis, the process in which material is transported from the cell interior to the extracellular space, proceeds through a complex mechanism. Defects in this process are linked to a number of serious illnesses including diabetes, cancer, and a range of neuropathologies. In neuroendocrine cells, exocytosis involves the fusion of secretory vesicles, carrying signaling molecules, with the plasma membrane through the coordinated interplay of proteins, lipids, and small molecules. This process is highly regulated and occurs in a complex three-dimensional environment within the cell precisely coupled to the stimulus. The study of exocytosis poses significant challenges, involving rapidly changing, nano-scale, protein-protein, and protein-lipid interactions, at specialized sites in the cell. Over the last decade our understanding of neuroendocrine exocytosis has been greatly enhanced by developments in fluorescence microscopy. Modern microscopy encompasses a toolbox of advanced techniques, pushing the limits of sensitivity and resolution, to probe different properties of exocytosis. In more recent years, the development of super-resolution microscopy techniques, side-stepping the limits of optical resolution imposed by the physical properties of light, have started to provide an unparalleled view of exocytosis. In this review we will discuss how advances in fluorescence microscopy are shedding light on the spatial and temporal organization of the exocytotic machinery.
Collapse
Affiliation(s)
- Alicja Graczyk
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, UK
| | - Colin Rickman
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, UK
- *Correspondence: Colin Rickman, Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK e-mail:
| |
Collapse
|
34
|
Hurst JH. Richard Scheller and Thomas Südhof receive the 2013 Albert Lasker Basic Medical Research Award. J Clin Invest 2013; 123:4095-101. [PMID: 24091319 DOI: 10.1172/jci72681] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
35
|
Dance of the SNAREs: assembly and rearrangements detected with FRET at neuronal synapses. J Neurosci 2013; 33:5507-23. [PMID: 23536066 DOI: 10.1523/jneurosci.2337-12.2013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptors (SNAREs) mediate vesicle fusion with the plasma membrane on activation by calcium binding to synaptotagmin. In the present study, we used fluorescence resonance energy transfer (FRET) and fluorescence lifetime imaging microscopy between fluorescently labeled SNARE proteins expressed in cultured rat hippocampal neurons to detect resting SNARE complexes, their conformational rearrangement on exocytosis, their disassembly before endocytosis of vesicular proteins, and SNARE assembly at newly docked vesicles. Assembled SNAREs are not only present in docked vesicles; unexpected residual "orphan SNARE complexes" also reside in para-active zone regions. Real-time changes in FRET between N-terminally labeled SNAP-25 and VAMP reported a reorientation of the SNARE motif upon exocytosis, SNARE disassembly in the active zone periphery, and SNARE reassembly in newly docked vesicles. With VAMP labeled C-terminally, decreased fluorescence in C-terminally labeled syntaxin (extracellular) reported trans-cis-conformational changes in SNAREs on vesicle fusion. After fusion SNAP-25 and syntaxin disperse along with VAMP, as well as the FRET signal itself, indicating diffusion of intact SNAREs after vesicle fusion but before their peripheral disassembly. Our measurements of spatiotemporal dynamics of SNARE conformational changes and movements refine models of SNARE function. Technical advances required to detect tiny changes in fluorescence in small fractions of labeled proteins in presynaptic boutons on a time scale of seconds permit the detection of rapid intermolecular interactions between small proportions of protein partners in cellular subcompartments.
Collapse
|
36
|
LegC3, an effector protein from Legionella pneumophila, inhibits homotypic yeast vacuole fusion in vivo and in vitro. PLoS One 2013; 8:e56798. [PMID: 23437241 PMCID: PMC3577674 DOI: 10.1371/journal.pone.0056798] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 01/15/2013] [Indexed: 12/12/2022] Open
Abstract
During infection, the intracellular pathogenic bacterium Legionella pneumophila causes an extensive remodeling of host membrane trafficking pathways, both in the construction of a replication-competent vacuole comprised of ER-derived vesicles and plasma membrane components, and in the inhibition of normal phagosome:endosome/lysosome fusion pathways. Here, we identify the LegC3 secreted effector protein from L. pneumophila as able to inhibit a SNARE- and Rab GTPase-dependent membrane fusion pathway in vitro, the homotypic fusion of yeast vacuoles (lysosomes). This vacuole fusion inhibition appeared to be specific, as similar secreted coiled-coiled domain containing proteins from L. pneumophila, LegC7/YlfA and LegC2/YlfB, did not inhibit vacuole fusion. The LegC3-mediated fusion inhibition was reversible by a yeast cytosolic extract, as well as by a purified soluble SNARE, Vam7p. LegC3 blocked the formation of trans-SNARE complexes during vacuole fusion, although we did not detect a direct interaction of LegC3 with the vacuolar SNARE protein complexes required for fusion. Additionally, LegC3 was incapable of inhibiting a defined synthetic model of vacuolar SNARE-driven membrane fusion, further suggesting that LegC3 does not directly inhibit the activity of vacuolar SNAREs, HOPS complex, or Sec17p/18p during membrane fusion. LegC3 is likely utilized by Legionella to modulate eukaryotic membrane fusion events during pathogenesis.
Collapse
|
37
|
Lord C, Ferro-Novick S, Miller EA. The highly conserved COPII coat complex sorts cargo from the endoplasmic reticulum and targets it to the golgi. Cold Spring Harb Perspect Biol 2013; 5:5/2/a013367. [PMID: 23378591 DOI: 10.1101/cshperspect.a013367] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Protein egress from the endoplasmic reticulum (ER) is driven by a conserved cytoplasmic coat complex called the COPII coat. The COPII coat complex contains an inner shell (Sec23/Sec24) that sorts cargo into ER-derived vesicles and an outer cage (Sec13/Sec31) that leads to coat polymerization. Once released from the ER, vesicles must tether to and fuse with the target membrane to deliver their protein and lipid contents. This delivery step also depends on the COPII coat, with coat proteins binding directly to tethering and regulatory factors. Recent findings have yielded new insight into how COPII-mediated vesicle traffic is regulated. Here we discuss the molecular basis of COPII-mediated ER-Golgi traffic, focusing on the surprising complexity of how ER-derived vesicles form, package diverse cargoes, and correctly target these cargoes to their destination.
Collapse
Affiliation(s)
- Christopher Lord
- Department of Cellular and Molecular Medicine, Howard Hughes Medical Institute, University of California at San Diego, La Jolla, CA 92093, USA
| | | | | |
Collapse
|
38
|
Kaneai N, Fukui K, Koike T, Urano S. Vitamin E Prevents Hyperoxia-Induced Loss of Soluble N-Ethylmaleimide-Sensitive Fusion Protein Attachment Protein Receptor Proteins in the Rat Neuronal Cytoplasm. Biol Pharm Bull 2013; 36:1500-2. [DOI: 10.1248/bpb.b13-00147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Nozomi Kaneai
- Life Support Technology Research Center, Shibaura Institute of Technology
| | - Koji Fukui
- Department of Bioscience & Engineering, Shibaura Institute of Technology
| | | | - Shiro Urano
- Life Support Technology Research Center, Shibaura Institute of Technology
| |
Collapse
|
39
|
Al-Abdul-Wahid MS, Demill CM, Serwin MB, Prosser RS, Stewart BA. Effect of juxtamembrane tryptophans on the immersion depth of Synaptobrevin, an integral vesicle membrane protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2994-9. [PMID: 22846509 DOI: 10.1016/j.bbamem.2012.07.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 07/20/2012] [Accepted: 07/23/2012] [Indexed: 01/25/2023]
Abstract
Proper positioning of membrane proteins in the host membrane is often critical to successful protein function. While hydrophobic considerations play a dominant role in determining the topology of a protein in the membrane, amphiphilic residues, such as tryptophan, may 'anchor' the protein near the water-membrane interface. The SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) family of membrane proteins mediates intracellular membrane fusion. Correct positioning of the SNAREs is necessary if fusion is to occur. Synaptobrevins are integral vesicle membrane proteins that are well conserved across species. Interestingly, mammalian Synaptobrevins typically contain two adjacent tryptophans near the water-membrane interface whereas the Drosophila, neuronal-Synaptobrevin (n-Syb), contains a single tryptophan in this same region. To explore the role of these tryptophan residues in membrane positioning, we prepared a peptide containing residues 75-121 of D. melanogaster n-Syb in DPC micelles, biosynthetically labeled with 4-fluorophenylalanine and 5-fluorotryptophan for the examination by ¹⁹F NMR spectroscopy. Mutations of this construct containing zero and two tryptophan residues near the water-membrane interface resulted in changes in the positioning of n-Syb in the micelle. Moreover, the addition of a second tryptophan appears to slow dynamic motions of n-Syb near the micelle-water interface. These data therefore indicate that juxtamembrane tryptophan residues are important determinants of the position of Synaptobrevin in the membrane.
Collapse
|
40
|
Rizo J, Rosen MK, Gardner KH. Enlightening molecular mechanisms through study of protein interactions. J Mol Cell Biol 2012; 4:270-83. [PMID: 22735643 DOI: 10.1093/jmcb/mjs036] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The investigation of molecular mechanisms is a fascinating area of current biological research that unites efforts from scientists with very diverse expertise. This review provides a perspective on the characterization of protein interactions as a central aspect of this research. We discuss case studies on the neurotransmitter release machinery that illustrate a variety of principles and emphasize the power of combining nuclear magnetic resonance (NMR) spectroscopy with other biophysical techniques, particularly X-ray crystallography. These studies have shown that: (i) the soluble SNAP receptor (SNARE) proteins form a tight complex that brings the synaptic vesicle and plasma membranes together, which is key for membrane fusion; (ii) the SNARE syntaxin-1 adopts an autoinhibitory closed conformation; (iii) Munc18-1 plays crucial functions through interactions with closed syntaxin-1 and with the SNARE complex; (iv) Munc13s mediate the opening of syntaxin-1; (v) complexins play dual roles through distinct interactions with the SNARE complex; (vi) synaptotagmin-1 acts a Ca(2+) sensor, interacting simultaneously with the membranes and the SNAREs; and (vii) a Munc13 homodimer to Munc13-RIM heterodimer switch modulates neurotransmitter release. Overall, this research underlines the complexities involved in elucidating molecular mechanisms and how these mechanisms can depend critically on an interplay between strong and weak protein interactions.
Collapse
Affiliation(s)
- Josep Rizo
- Department of Biophysics, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA.
| | | | | |
Collapse
|
41
|
Park SJ, Jang HR, Kim M, Kim JH, Kwon OH, Park JL, Noh SM, Song KS, Kim SY, Kim YH, Kim YS. Epigenetic alteration of CCDC67 and its tumor suppressor function in gastric cancer. Carcinogenesis 2012; 33:1494-501. [PMID: 22610074 DOI: 10.1093/carcin/bgs178] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
In this study, the promoter of the gene coiled-coil domain-containing 67 (CCDC67) was found to be frequently methylated in gastric cancer cell lines and in primary gastric tumors, as examined by restriction landmark genomic scanning. In addition, CCDC67 expression was down-regulated in 72.7% of gastric cancer cell lines tested. In most cases, gene down-regulation was associated with CpG hypermethylation in the CCDC67 promoter. Treatment with 5-aza-2'-deoxycytidine and/or trichostatin A restored CCDC67 expression in down-regulated cell lines. Pyrosequencing analysis of 150 paired primary gastric cancer samples revealed that promoter CpG methylation was increased in 74% of tested tumors compared with paired adjacent normal tissues, and this hypermethylation correlated significantly with down-regulation of CCDC67. CCDC67 protein was localized to the cell membrane by immunocytochemistry. Stable transfection of a CCDC67 gene in one gastric cancer cell line inhibited adhesion-dependent and -independent colony formation, and CCDC67 expression suppressed tumorigenesis in nude mice. We suggest that CCDC67 is a putative tumor suppressor gene that is silenced in gastric cancers by promoter CpG methylation and that it may play an important role in cell signaling and migration related to tumorigenesis.
Collapse
Affiliation(s)
- Sung-Joon Park
- Medical Genomics Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Detection of SNARE complexes with FRET using the tetracysteine system. Biotechniques 2012; 52:103-8. [DOI: 10.2144/000113811] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 12/30/2011] [Indexed: 11/23/2022] Open
Abstract
The three proteins synaptosomal-associated protein 25 (SNAP-25), Syntaxin-1a and vesicle-associated membrane protein (VAMP-2) are collectively called SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors). By assembling into an exocytic complex, the three SNAREs help in catalyzing membrane fusion. Due to lack of probes that adequately reconstitute the intracellular behavior of endogenous SNAREs, the dynamics of SNARE complexes in living cells is poorly understood. Here we describe a new FRET-based probe, called Cerulean-SNAP-25-C4 (CSNAC), that can track the conformational changes undergone by SNAP-25 as exocytic complexes assemble. The fluorescent protein Cerulean was attached to the N terminus and served as a FRET donor. The biarsenical dye FlAsH served as a FRET acceptor and was attached to a short tetracysteine motif (C4) motif inserted into the so-called linker domain of SNAP-25. CSNAC reported successive FRET changes when first Syntaxin-1a and then VAMP-2 were added in vitro. Small tetracysteine insertions used as a FRET acceptor are expected to have less steric hindrance than previously used GFP-based fluorophores. We propose that genetically-encoded tetracysteine tags can be used to study regulated SNARE complex assembly in vivo.
Collapse
|
43
|
Liu W, Montana V, Parpura V, Mohideen U. Single-molecule measurements of dissociation rates and energy landscapes of binary trans snare complexes in parallel versus antiparallel orientation. Biophys J 2011; 101:1854-62. [PMID: 22004738 PMCID: PMC3192972 DOI: 10.1016/j.bpj.2011.08.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 07/27/2011] [Accepted: 08/11/2011] [Indexed: 10/16/2022] Open
Abstract
Interactions between synaptobrevin 2 (Sb2) and syntaxin 1A (Sx1A) can be readily isolated and studied with the use of force spectroscopy single-molecule measurements. We studied interactions between Sx1A and Sb2 in two different orientations (parallel and antiparallel) using four different terminus configurations of these proteins. Force-loading experiments indicated that protein pairs in any configuration/orientation are zippered. We measured the extension and force for disassembly of these interactions, calculated the spontaneous dissociation lifetimes, and determined their free energies, enthalpies, and entropies. Although the free energies were very similar for all four configurations (∼28 k(B)T (Eyring model) and ∼20 k(B)T (Kramers model)), the enthalpy changes of binary Sx1A-Sb2 interactions varied between 24.7 k(B)T and 33.1 k(B)T. This variation is consistent with the conformation changes that occur during disassembly of the various protein terminus configurations, as verified by alterations in the extension. The parallel interactions appear to be energetically somewhat advantageous over antiparallel configurations/orientation, especially when the N-termini of Sx1A-Sb2 are left to interact freely.
Collapse
Affiliation(s)
- Wei Liu
- Department of Physics and Astronomy, University of California, Riverside, California
- Center for Nanoscale Science and Engineering, University of California, Riverside, California
| | - Vedrana Montana
- Department of Cell Biology and Neuroscience, University of California, Riverside, California
- Center for Glial-Neuronal Interactions, University of California, Riverside, California
| | - Vladimir Parpura
- Department of Physics and Astronomy, University of California, Riverside, California
- Department of Cell Biology and Neuroscience, University of California, Riverside, California
- Center for Glial-Neuronal Interactions, University of California, Riverside, California
- Center for Nanoscale Science and Engineering, University of California, Riverside, California
| | - U. Mohideen
- Department of Physics and Astronomy, University of California, Riverside, California
- Center for Nanoscale Science and Engineering, University of California, Riverside, California
| |
Collapse
|
44
|
Two synaptobrevin molecules are sufficient for vesicle fusion in central nervous system synapses. Proc Natl Acad Sci U S A 2011; 108:14318-23. [PMID: 21844343 DOI: 10.1073/pnas.1101818108] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Exocytosis of synaptic vesicles (SVs) during fast synaptic transmission is mediated by soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex assembly formed by the coil-coiling of three members of this protein family: vesicle SNARE protein, synaptobrevin 2 (syb2), and the presynaptic membrane SNAREs syntaxin-1A and SNAP-25. However, it is controversially debated how many SNARE complexes are minimally needed for SV priming and fusion. To quantify this effective number, we measured the fluorescence responses from single fusing vesicles expressing pHluorin (pHl), a pH-sensitive variant of GFP, fused to the luminal domain of the vesicular SNARE syb2 (spH) in cultured hippocampal neurons lacking endogenous syb2. Fluorescence responses were quantal, with the unitary signals precisely corresponding to single pHluorin molecules. Using this approach we found that two copies of spH per SV fully rescued evoked fusion whereas SVs expressing only one spH were unable to rapidly fuse upon stimulation. Thus, two syb2 molecules and likely two SNARE complexes are necessary and sufficient for SV fusion during fast synaptic transmission.
Collapse
|
45
|
Hussain S, Davanger S. The discovery of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex and the molecular regulation of synaptic vesicle transmitter release: the 2010 Kavli Prize in neuroscience. Neuroscience 2011; 190:12-20. [PMID: 21641968 DOI: 10.1016/j.neuroscience.2011.05.057] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 05/16/2011] [Indexed: 11/25/2022]
Abstract
Brain function depends on a crucial feature: The ability of individual neurons to share packets of information, known as quantal transmission. Given the sheer number of tasks the brain has to deal with, this information sharing must be extremely rapid. Synapses are specialized points of contact between neurons, where fast transmission takes place. Though the basic elements and functions of the synapse had been established since the 1950s, the molecular basis for regulation of fast synaptic transmitter release was not known 20 years ago. However, around 1990, crucial discoveries were made by Richard Scheller, James Rothman, and Thomas Südhof, leading a few years later to the formulation of the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) hypothesis and a new understanding of the molecular events controlling vesicular release of transmitter in synapses. The 2010 Kavli Prize in neuroscience was awarded to these three researchers, "for their work to reveal the precise molecular basis of the transfer of signals between nerve cells in the brain."
Collapse
Affiliation(s)
- S Hussain
- Institute of Basic Medical Science, and Centre for Molecular Biology and Neuroscience, University of Oslo, PO Box 1105 Blindern, 0317 Oslo, Norway
| | | |
Collapse
|
46
|
Maj M, Ilhan A, Neziri D, Gartner W, Berggard T, Attems J, Base W, Wagner L. Age related changes in pancreatic beta cells: A putative extra-cerebral site of Alzheimer’s pathology. World J Diabetes 2011; 2:49-53. [PMID: 21537460 PMCID: PMC3083907 DOI: 10.4239/wjd.v2.i4.49] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 03/29/2011] [Accepted: 04/05/2011] [Indexed: 02/05/2023] Open
Abstract
Frequent concomitant manifestation of type 2 diabetes mellitus (T2DM) and Alzheimer’s disease (AD) has been recently demonstrated by epidemiological studies. This might be due to functional similarities between β-cells and neurons, such as secretion on demand of highly specific molecules in a tightly controlled fashion. An additional similarity represents the age-related alteration of hyperphosphorylated tau in AD patients. Similarly, alterations have been identified in β-cells of T2DM patients. The islet amyloid polypeptide has been associated with β-cell apoptosis. As a consequence of increasing age, the accumulation of highly modified proteins together with decreased regenerative potential might lead to increasing rates of apoptosis. Moreover, reduction of β-cell replication capabilities results in reduction of β-cell mass in mammals, simultaneously with impaired glucose tolerance. The new challenge is to learn much more about age-related protein modifications. This can lead to new treatment strategies for reducing the incidence of T2DM and AD.
Collapse
Affiliation(s)
- Magdalena Maj
- Magdalena Maj, Aysegul Ilhan, Dashurie Neziri, Wolfgang Gartner, Department of Internal Medicine III, Division of Nephrology and Dialysis, Medical University of Vienna, 1090 Vienna, Austria
| | | | | | | | | | | | | | | |
Collapse
|
47
|
Meyenberg K, Lygina AS, van den Bogaart G, Jahn R, Diederichsen U. SNARE derived peptide mimic inducing membrane fusion. Chem Commun (Camb) 2011; 47:9405-7. [DOI: 10.1039/c1cc12879e] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
48
|
Dun AR, Rickman C, Duncan RR. The t-SNARE complex: a close up. Cell Mol Neurobiol 2010; 30:1321-6. [PMID: 21046449 DOI: 10.1007/s10571-010-9599-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Accepted: 09/03/2010] [Indexed: 11/26/2022]
Abstract
The SNARE proteins, syntaxin, SNAP-25, and synaptobrevin have long been known to provide the driving force for vesicle fusion in the process of regulated exocytosis. Of particular interest is the initial interaction between SNAP-25 and syntaxin to form the t-SNARE heterodimer, an acceptor for subsequent synaptobrevin engagement. In vitro studies have revealed at least two different dynamic conformations of t-SNARE heterodimer defined by the degree of association of the C-terminal SNARE motif of SNAP-25 with syntaxin. At the plasma membrane, these proteins are organized into dense clusters of 50-60 nm in diameter. More recently, the t-SNARE interaction within these clusters was investigated in live cells at the molecular level, estimating each cluster to contain 35-70 t-SNARE molecules. This work reported the presence of both partially and fully zippered t-SNARE complex at the plasma membrane in agreement with the earlier in vitro findings. It also revealed a spatial segregation into distinct clusters containing predominantly one conformation apparently patterned by the surrounding lipid environment. The reason for this dynamic t-SNARE complex in exocytosis is uncertain; however, it does take us one step closer to understand the complex sequence of events leading to vesicle fusion, emphasizing the role of both membrane proteins and lipids.
Collapse
Affiliation(s)
- Alison R Dun
- Centre for Integrative Physiology, University of Edinburgh Medical School, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | | | | |
Collapse
|
49
|
Plattner H. How to Design a Highly Organized Cell: An Unexpectedly High Number of Widely Diversified SNARE Proteins Positioned at Strategic Sites in the Ciliate, Paramecium tetraurelia. Protist 2010; 161:497-516. [DOI: 10.1016/j.protis.2010.05.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
50
|
Liu W, Parpura V. SNAREs: could they be the answer to an energy landscape riddle in exocytosis? ScientificWorldJournal 2010; 10:1258-68. [PMID: 20602083 PMCID: PMC2908314 DOI: 10.1100/tsw.2010.137] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
During exocytosis, chemical transmitters stored in secretory vesicles can be released upon fusion of these intracellular organelles to the plasma membrane. In this process, SNARE proteins that form a ternary core complex play a central role. This complex could provide the means for generation/storage of energy necessary for driving the fusion of vesicular and plasma membranes. Recently, the amount of energy for (dis)assembly of the ternary complex has been measured using various experimental approaches, including atomic force microscopy, the surface force apparatus, and isothermal titration calorimetry. The obtained measurements are in good agreement with the calculated energy required for membrane fusion achieved by theoretical modeling approaches. Whether the energy expenditure to form the ternary SNARE complex can be utilized towards membrane fusion and/or docking/tethering of vesicles to the plasma membrane still remains one of the key contemporary issues in biophysics and neuroscience.
Collapse
Affiliation(s)
- Wei Liu
- Department of Neurobiology, Atomic Force Microscopy and Nanotechnology Laboratories, Center for Glial Biology in Medicine, Civitan International Research Center, and Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, USA.
| | | |
Collapse
|