1
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Clark JC, Martin EM, Morán LA, Di Y, Wang X, Zuidscherwoude M, Brown HC, Kavanagh DM, Hummert J, Eble JA, Nieswandt B, Stegner D, Pollitt AY, Herten DP, Tomlinson MG, García A, Watson SP. Divalent nanobodies to platelet CLEC-2 can serve as agonists or antagonists. Commun Biol 2023; 6:376. [PMID: 37029319 PMCID: PMC10082178 DOI: 10.1038/s42003-023-04766-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 03/27/2023] [Indexed: 04/09/2023] Open
Abstract
CLEC-2 is a target for a new class of antiplatelet agent. Clustering of CLEC-2 leads to phosphorylation of a cytosolic YxxL and binding of the tandem SH2 domains in Syk, crosslinking two receptors. We have raised 48 nanobodies to CLEC-2 and crosslinked the most potent of these to generate divalent and tetravalent nanobody ligands. Fluorescence correlation spectroscopy (FCS) was used to show that the multivalent nanobodies cluster CLEC-2 in the membrane and that clustering is reduced by inhibition of Syk. Strikingly, the tetravalent nanobody stimulated aggregation of human platelets, whereas the divalent nanobody was an antagonist. In contrast, in human CLEC-2 knock-in mouse platelets, the divalent nanobody stimulated aggregation. Mouse platelets express a higher level of CLEC-2 than human platelets. In line with this, the divalent nanobody was an agonist in high-expressing transfected DT40 cells and an antagonist in low-expressing cells. FCS, stepwise photobleaching and non-detergent membrane extraction show that CLEC-2 is a mixture of monomers and dimers, with the degree of dimerisation increasing with expression thereby favouring crosslinking of CLEC-2 dimers. These results identify ligand valency, receptor expression/dimerisation and Syk as variables that govern activation of CLEC-2 and suggest that divalent ligands should be considered as partial agonists.
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Affiliation(s)
- Joanne C Clark
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK.
| | - Eleyna M Martin
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Luis A Morán
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Centre for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), Santiago de Compostela, Spain
| | - Ying Di
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Xueqing Wang
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Centre for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), Santiago de Compostela, Spain
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Malou Zuidscherwoude
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
| | - Helena C Brown
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Deirdre M Kavanagh
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 QU3, UK
| | - Johan Hummert
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
| | - Johannes A Eble
- Institute for Physiological Chemistry & Pathobiochemistry, University of Münster, Waldeyerstraße 15, 48149, Münster, Germany
| | - Bernhard Nieswandt
- Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - David Stegner
- Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Alice Y Pollitt
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, RG6 6AS, UK
| | - Dirk-Peter Herten
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
| | - Michael G Tomlinson
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Angel García
- Centre for Research in Molecular Medicine and Chronic Diseases (CIMUS), Universidade de Santiago de Compostela, and Instituto de Investigación Sanitaria de Santiago (IDIS), Santiago de Compostela, Spain
| | - Steve P Watson
- Institute of Cardiovascular Sciences, Level 1 IBR, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
- Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, UK.
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2
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Bademosi AT, Meunier FA. Unveiling the Nanoscale Dynamics of the Exocytic Machinery in Chromaffin Cells with Single-Molecule Imaging. Methods Mol Biol 2023; 2565:311-327. [PMID: 36205903 DOI: 10.1007/978-1-0716-2671-9_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Neuronal and hormonal communication relies on the exocytic fusion of vesicles containing neurotransmitters and hormones with the plasma membrane. This process is tightly regulated by key protein-protein and protein-lipid interactions and culminates in the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex formation and zippering that promotes vesicular fusion. Located on both sides of the vesicle and the plasma membrane, the zippering of the SNARE complex acts to overcome the energy barrier afforded by the repulsive electrostatic force stemming from apposing two negatively charged phospholipid membranes. Another component opposing the timely organization of the fusion machinery is thermal Brownian energy that tends to homogenize all cellular molecules by constantly switching their motions and directions through short-lived molecular interactions. Much less is known of the mechanisms counteracting these chaotic forces, allowing seamless cellular functions such as exocytic fusion. Super-resolution microscopy techniques such as single-molecule imaging have proven useful to start uncovering these nanoscale mechanisms. Here, we used single-particle tracking photoactivatable localization microscopy (sptPALM) to track syntaxin-1-mEos, a SNARE protein located on the plasma membrane of cultured bovine chromaffin cells. We demonstrate that syntaxin-1-mEos undergoes dramatic change in its mobility in response to secretagogue stimulation leading to increased nanoclustering. These nanoclusters are transient in nature and likely to provide docked vesicles with a molecular environment conducive to exocytic fusion.
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Affiliation(s)
- Adekunle T Bademosi
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland, St Lucia Campus, Brisbane, QLD, Australia.
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland, St Lucia Campus, Brisbane, QLD, Australia.
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Ejdrup AL, Lycas MD, Lorenzen N, Konomi A, Herborg F, Madsen KL, Gether U. A density-based enrichment measure for assessing colocalization in single-molecule localization microscopy data. Nat Commun 2022; 13:4388. [PMID: 35902578 PMCID: PMC9334352 DOI: 10.1038/s41467-022-32064-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 07/15/2022] [Indexed: 11/20/2022] Open
Abstract
Dual-color single-molecule localization microscopy (SMLM) provides unprecedented possibilities for detailed studies of colocalization of different molecular species in a cell. However, the informational richness of the data is not fully exploited by current analysis tools that often reduce colocalization to a single value. Here, we describe a tool specifically designed for determination of co-localization in both 2D and 3D from SMLM data. The approach uses a function that describes the relative enrichment of one molecular species on the density distribution of a reference species. The function reframes the question of colocalization by providing a density-context relevant to multiple biological questions. Moreover, the function visualize enrichment (i.e. colocalization) directly in the images for easy interpretation. We demonstrate the approach’s functionality on both simulated data and cultured neurons, and compare it to current alternative measures. The method is available in a Python function for easy and parameter-free implementation. Full information gained from single-molecule localisation microscopy (SMLM) isn't exploited by current analysis tools. Here the authors report relative enrichment which uses a density-based colocalisation measure for both 2D and 3D SMLM data; they apply it to both simulated data and cultured neurons.
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Affiliation(s)
- Aske L Ejdrup
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Matthew D Lycas
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Niels Lorenzen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ainoa Konomi
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Freja Herborg
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kenneth L Madsen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ulrik Gether
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Hu Y, Liu J, Yu J, Yang F, Zhang M, Liu Y, Ma S, Zhou X, Wang J, Han Y. Identification and validation a costimulatory molecule gene signature to predict the prognosis and immunotherapy response for hepatocellular carcinoma. Cancer Cell Int 2022; 22:97. [PMID: 35193632 PMCID: PMC8864933 DOI: 10.1186/s12935-022-02514-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 02/05/2022] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. Costimulatory molecules have been proven to be the foundation of immunotherapy. However, the potential roles of costimulatory molecule genes (CMGs) in HCC remain unclear. Our study is aimed to develop a costimulatory molecule-related gene signature that could evaluate the prognosis of HCC patients. METHODS Based on The Cancer Gene Atlas (TCGA) database, univariate Cox regression analysis was applied in CMGs to identify prognosis-related CMGs. Consensus clustering analysis was performed to stratify HCC patients into different subtypes and compared them in OS. Subsequently, the LASSO Cox regression analysis was performed to construct the CMGs-related prognostic signature and Kaplan-Meier survival curves as well as ROC curve were used to validate the predictive capability. Then we explored the correlations of the risk signature with tumor-infiltrating immune cells, tumor mutation burden (TMB) and response to immunotherapy. The expression levels of prognosis-related CMGs were validated based on qRT-PCR and Human Protein Atlas (HPA) databases. RESULTS All HCC patients were classified into two clusters based on 11 CMGs with prognosis values and cluster 2 correlated with a poorer prognosis. Next, a prognostic signature of six CMGs was constructed, which was an independent risk factor for HCC patients. Patients with low-risk score were associated with better prognosis. The correlation analysis showed that the risk signature could predict the infiltration of immune cells and immune status of the immune microenvironment in HCC. The qRT-PCR and immunohistochemical results indicated six CMGs with differential expression in HCC tissues and normal tissues. CONCLUSION In conclusion, our CMGs-related risk signature could be used as a prediction tool in survival assessment and immunotherapy for HCC patients.
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Affiliation(s)
- Yinan Hu
- Institute of Digestive Diseases, Xijing Hospital, Air Force Medical University, Xi'an, 710032, Shaanxi, China
| | - Jingyi Liu
- Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, Xi'an, 710032, Shaanxi, China
| | - Jiahao Yu
- Institute of Digestive Diseases, Xijing Hospital, Air Force Medical University, Xi'an, 710032, Shaanxi, China
| | - Fangfang Yang
- Institute of Digestive Diseases, Xijing Hospital, Air Force Medical University, Xi'an, 710032, Shaanxi, China
| | - Miao Zhang
- Institute of Digestive Diseases, Xijing Hospital, Air Force Medical University, Xi'an, 710032, Shaanxi, China
| | - Yansheng Liu
- Institute of Digestive Diseases, Xijing Hospital, Air Force Medical University, Xi'an, 710032, Shaanxi, China
| | - Shuoyi Ma
- Institute of Digestive Diseases, Xijing Hospital, Air Force Medical University, Xi'an, 710032, Shaanxi, China
| | - Xia Zhou
- Institute of Digestive Diseases, Xijing Hospital, Air Force Medical University, Xi'an, 710032, Shaanxi, China
| | - Jingbo Wang
- Institute of Digestive Diseases, Xijing Hospital, Air Force Medical University, Xi'an, 710032, Shaanxi, China
| | - Ying Han
- Institute of Digestive Diseases, Xijing Hospital, Air Force Medical University, Xi'an, 710032, Shaanxi, China.
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5
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Clayton EL, Bonnycastle K, Isaacs AM, Cousin MA, Schorge S. A novel synaptopathy-defective synaptic vesicle protein trafficking in the mutant CHMP2B mouse model of frontotemporal dementia. J Neurochem 2022; 160:412-425. [PMID: 34855215 DOI: 10.1111/jnc.15551] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 11/10/2021] [Accepted: 11/18/2021] [Indexed: 12/13/2022]
Abstract
Mutations in the ESCRT-III subunit CHMP2B cause frontotemporal dementia (FTD) and lead to impaired endolysosomal trafficking and lysosomal storage pathology in neurons. We investigated the effect of mutant CHMP2B on synaptic pathology, as ESCRT function was recently implicated in the degradation of synaptic vesicle (SV) proteins. We report here that expression of C-terminally truncated mutant CHMP2B results in a novel synaptopathy. This unique synaptic pathology is characterised by selective retention of presynaptic SV trafficking proteins in aged mutant CHMP2B transgenic mice, despite significant loss of postsynaptic proteins. Furthermore, ultrastructural analysis of primary cortical cultures from transgenic CHMP2B mice revealed a significant increase in the number of presynaptic endosomes, while neurons expressing mutant CHMP2B display defective SV recycling and alterations to functional SV pools. Therefore, we reveal how mutations in CHMP2B affect specific presynaptic proteins and SV recycling, identifying CHMP2B FTD as a novel synaptopathy. This novel synaptopathic mechanism of impaired SV physiology may be a key early event in multiple forms of FTD, since proteins that mediate the most common genetic forms of FTD all localise at the presynapse.
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Affiliation(s)
- Emma L Clayton
- Department of Pharmacology, UCL School of Pharmacy, London, UK
- Currently at UK Dementia Research Institute at King's College London, London, UK
| | - Katherine Bonnycastle
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, Scotland
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, Scotland
| | - Adrian M Isaacs
- UK Dementia Research Institute at UCL, London, UK
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, Scotland
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, Scotland
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6
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Valli J, Garcia-Burgos A, Rooney LM, Vale de Melo E Oliveira B, Duncan RR, Rickman C. Seeing beyond the limit: A guide to choosing the right super-resolution microscopy technique. J Biol Chem 2021; 297:100791. [PMID: 34015334 PMCID: PMC8246591 DOI: 10.1016/j.jbc.2021.100791] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 05/14/2021] [Accepted: 05/14/2021] [Indexed: 02/06/2023] Open
Abstract
Super-resolution microscopy has become an increasingly popular and robust tool across the life sciences to study minute cellular structures and processes. However, with the increasing number of available super-resolution techniques has come an increased complexity and burden of choice in planning imaging experiments. Choosing the right super-resolution technique to answer a given biological question is vital for understanding and interpreting biological relevance. This is an often-neglected and complex task that should take into account well-defined criteria (e.g., sample type, structure size, imaging requirements). Trade-offs in different imaging capabilities are inevitable; thus, many researchers still find it challenging to select the most suitable technique that will best answer their biological question. This review aims to provide an overview and clarify the concepts underlying the most commonly available super-resolution techniques as well as guide researchers through all aspects that should be considered before opting for a given technique.
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Affiliation(s)
- Jessica Valli
- Edinburgh Super Resolution Imaging Consortium (ESRIC), Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, United Kingdom.
| | - Adrian Garcia-Burgos
- Edinburgh Super Resolution Imaging Consortium (ESRIC), Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, United Kingdom
| | - Liam M Rooney
- Edinburgh Super Resolution Imaging Consortium (ESRIC), Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, United Kingdom
| | - Beatriz Vale de Melo E Oliveira
- Edinburgh Super Resolution Imaging Consortium (ESRIC), Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, United Kingdom
| | - Rory R Duncan
- Edinburgh Super Resolution Imaging Consortium (ESRIC), Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, United Kingdom
| | - Colin Rickman
- Edinburgh Super Resolution Imaging Consortium (ESRIC), Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, United Kingdom.
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7
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Harper CB, Smillie KJ. Current molecular approaches to investigate pre-synaptic dysfunction. J Neurochem 2021; 157:107-129. [PMID: 33544872 DOI: 10.1111/jnc.15316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/19/2022]
Abstract
Over the course of the last few decades it has become clear that many neurodevelopmental and neurodegenerative disorders have a synaptic defect, which contributes to pathogenicity. A rise in new techniques, and in particular '-omics'-based methods providing large datasets, has led to an increase in potential proteins and pathways implicated in synaptic function and related disorders. Additionally, advancements in imaging techniques have led to the recent discovery of alternative modes of synaptic vesicle recycling. This has resulted in a lack of clarity over the precise role of different pathways in maintaining synaptic function and whether these new pathways are dysfunctional in neurodevelopmental and neurodegenerative disorders. A greater understanding of the molecular detail of pre-synaptic function in health and disease is key to targeting new proteins and pathways for novel treatments and the variety of new techniques currently available provides an ideal opportunity to investigate these functions. This review focuses on techniques to interrogate pre-synaptic function, concentrating mainly on synaptic vesicle recycling. It further examines techniques to determine the underlying molecular mechanism of pre-synaptic dysfunction and discusses methods to identify molecular targets, along with protein-protein interactions and cellular localization. In combination, these techniques will provide an expanding and more complete picture of pre-synaptic function. With the application of recent technological advances, we are able to resolve events with higher spatial and temporal resolution, leading research towards a greater understanding of dysfunction at the presynapse and the role it plays in pathogenicity.
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Affiliation(s)
- Callista B Harper
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
| | - Karen J Smillie
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
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8
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Clark JC, Neagoe RAI, Zuidscherwoude M, Kavanagh DM, Slater A, Martin EM, Soave M, Stegner D, Nieswandt B, Poulter NS, Hummert J, Herten DP, Tomlinson MG, Hill SJ, Watson SP. Evidence that GPVI is Expressed as a Mixture of Monomers and Dimers, and that the D2 Domain is not Essential for GPVI Activation. Thromb Haemost 2021; 121:1435-1447. [PMID: 33638140 DOI: 10.1055/a-1401-5014] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Collagen has been proposed to bind to a unique epitope in dimeric glycoprotein VI (GPVI) and the number of GPVI dimers has been reported to increase upon platelet activation. However, in contrast, the crystal structure of GPVI in complex with collagen-related peptide (CRP) showed binding distinct from the site of dimerization. Further fibrinogen has been reported to bind to monomeric but not dimeric GPVI. In the present study, we have used the advanced fluorescence microscopy techniques of single-molecule microscopy, fluorescence correlation spectroscopy (FCS) and bioluminescence resonance energy transfer (BRET), and mutagenesis studies in a transfected cell line model to show that GPVI is expressed as a mixture of monomers and dimers and that dimerization through the D2 domain is not critical for activation. As many of these techniques cannot be applied to platelets to resolve this issue, due to the high density of GPVI and its anucleate nature, we used Förster resonance energy transfer (FRET) to show that endogenous GPVI is at least partially expressed as a dimer on resting and activated platelet membranes. We propose that GPVI may be expressed as a monomer on the cell surface and it forms dimers in the membrane through diffusion, giving rise to a mixture of monomers and dimers. We speculate that the formation of dimers facilitates ligand binding through avidity.
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Affiliation(s)
- Joanne C Clark
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom
| | - Raluca A I Neagoe
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center, University of Wurzburg, Wurzburg, Germany
| | - Malou Zuidscherwoude
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom
| | - Deirdre M Kavanagh
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom
| | - Alexandre Slater
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Eleyna M Martin
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Mark Soave
- Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom.,Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - David Stegner
- Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center, University of Wurzburg, Wurzburg, Germany
| | - Bernhard Nieswandt
- Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center, University of Wurzburg, Wurzburg, Germany
| | - Natalie S Poulter
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom
| | - Johan Hummert
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom.,Department for Physical Chemistry, Heidelberg University, Heidelberg, Germany
| | - Dirk-Peter Herten
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom.,Department for Physical Chemistry, Heidelberg University, Heidelberg, Germany
| | - Michael G Tomlinson
- Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom.,School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Stephen J Hill
- Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom.,Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Steve P Watson
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.,Centre of Membrane Proteins and Receptors, The Universities of Birmingham and Nottingham, The Midlands, United Kingdom
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9
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Tang F, Xiao D, Chen L, Gao H, Li X. Role of Munc18-1 in the biological functions and pathogenesis of neurological disorders (Review). Mol Med Rep 2021; 23:198. [PMID: 33495808 PMCID: PMC7821349 DOI: 10.3892/mmr.2021.11837] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 12/30/2020] [Indexed: 11/06/2022] Open
Abstract
The release of neurotransmitters following the fusion of synaptic vesicles and the presynaptic membrane is an important process in the transmission of neuronal information. Syntaxin-binding protein 1 (Munc18-1) is a synaptic fusion protein binding protein, which mainly regulates synaptic vesicle fusion and neurotransmitter release by interacting with soluble N-ethylmaleimide sensitive factor attachment protein receptor. In addition to affecting neurotransmitter transmission, Munc18-1 is also involved in regulating neurosynaptic plasticity, neurodevelopment and neuroendocrine cell release functions (including thyroxine and insulin release). A number of previous studies have demonstrated that Munc18-1 has diverse and vital biological functions, and that its abnormal expression serves an important role in the pathogenesis of a variety of neurological diseases, including epileptic encephalopathy, schizophrenia, autism, Parkinsons disease, Alzheimers disease, multiple sclerosis, Duchennes muscular dystrophy and neuronal ceroid lipofuscinosis. The present review summarizes the function of Munc18-1 and its possible relationship to the pathogenesis of various neurological diseases.
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Affiliation(s)
- Fajuan Tang
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Dongqiong Xiao
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Lin Chen
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Hu Gao
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Xihong Li
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
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10
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Carvalhais LG, Martinho VC, Ferreiro E, Pinheiro PS. Unraveling the Nanoscopic Organization and Function of Central Mammalian Presynapses With Super-Resolution Microscopy. Front Neurosci 2021; 14:578409. [PMID: 33584169 PMCID: PMC7874199 DOI: 10.3389/fnins.2020.578409] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 12/03/2020] [Indexed: 12/22/2022] Open
Abstract
The complex, nanoscopic scale of neuronal function, taking place at dendritic spines, axon terminals, and other minuscule structures, cannot be adequately resolved using standard, diffraction-limited imaging techniques. The last couple of decades saw a rapid evolution of imaging methods that overcome the diffraction limit imposed by Abbe's principle. These techniques, including structured illumination microscopy (SIM), stimulated emission depletion (STED), photo-activated localization microscopy (PALM), and stochastic optical reconstruction microscopy (STORM), among others, have revolutionized our understanding of synapse biology. By exploiting the stochastic nature of fluorophore light/dark states or non-linearities in the interaction of fluorophores with light, by using modified illumination strategies that limit the excitation area, these methods can achieve spatial resolutions down to just a few tens of nm or less. Here, we review how these advanced imaging techniques have contributed to unprecedented insight into the nanoscopic organization and function of mammalian neuronal presynapses, revealing new organizational principles or lending support to existing views, while raising many important new questions. We further discuss recent technical refinements and newly developed tools that will continue to expand our ability to delve deeper into how synaptic function is orchestrated at the nanoscopic level.
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Affiliation(s)
- Lia G Carvalhais
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Vera C Martinho
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Elisabete Ferreiro
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Paulo S Pinheiro
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
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11
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Lobb IT, Morin P, Martin K, Thoms HC, Wills JC, Lleshi X, Olsen KCF, Duncan RR, Stark LA. A Role for the Autophagic Receptor, SQSTM1/p62, in Trafficking NF-κB/RelA to Nucleolar Aggresomes. Mol Cancer Res 2020; 19:274-287. [PMID: 33097627 DOI: 10.1158/1541-7786.mcr-20-0336] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 09/18/2020] [Accepted: 10/16/2020] [Indexed: 11/16/2022]
Abstract
Elevated NF-κB activity is a contributory factor in many hematologic and solid malignancies. Nucleolar sequestration of NF-κB/RelA represses this elevated activity and mediates apoptosis of cancer cells. Here, we set out to understand the mechanisms that control the nuclear/nucleolar distribution of RelA and other regulatory proteins, so that agents can be developed that specifically target these proteins to the organelle. We demonstrate that RelA accumulates in intranucleolar aggresomes in response to specific stresses. We also demonstrate that the autophagy receptor, SQSTM1/p62, accumulates alongside RelA in these nucleolar aggresomes. This accumulation is not a consequence of inhibited autophagy. Indeed, our data suggest nucleolar and autophagosomal accumulation of p62 are in active competition. We identify a conserved motif at the N-terminus of p62 that is essential for nucleoplasmic-to-nucleolar transport of the protein. Furthermore, using a dominant-negative mutant deleted for this nucleolar localization signal (NoLS), we demonstrate a role for p62 in trafficking RelA and other aggresome-related proteins to nucleoli, to induce apoptosis. Together, these data identify a novel role for p62 in trafficking nuclear proteins to nucleolar aggresomes under conditions of cell stress, thus maintaining cellular homeostasis. They also provide invaluable information on the mechanisms that regulate the nuclear/nucleolar distribution of RelA that could be exploited for therapeutic purpose. IMPLICATIONS: The data open up avenues for the development of a unique class of therapeutic agents that act by targeting RelA and other aberrantly active proteins to nucleoli, thus killing cancer cells.
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Affiliation(s)
- Ian T Lobb
- Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, Scotland
| | - Pierre Morin
- Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, Scotland
| | - Kirsty Martin
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Edinburgh, Scotland
| | - Hazel C Thoms
- Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, Scotland
| | | | - Xhordi Lleshi
- Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, Scotland
| | - Karl C F Olsen
- Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, Scotland
| | - Rory R Duncan
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Edinburgh, Scotland
| | - Lesley A Stark
- Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, Scotland.
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12
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Saleeb RS, Kavanagh DM, Dun AR, Dalgarno PA, Duncan RR. A VPS33A-binding motif on syntaxin 17 controls autophagy completion in mammalian cells. J Biol Chem 2019; 294:4188-4201. [PMID: 30655294 PMCID: PMC6422071 DOI: 10.1074/jbc.ra118.005947] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 12/21/2018] [Indexed: 01/24/2023] Open
Abstract
Autophagy is an intracellular degradation pathway that transports cytoplasmic material to the lysosome for hydrolysis. It is completed by SNARE-mediated fusion of the autophagosome and endolysosome membranes. This process must be carefully regulated to maintain the organization of the membrane system and prevent mistargeted degradation. As yet, models of autophagosomal fusion have not been verified within a cellular context because of difficulties with assessing protein interactions in situ Here, we used high-resolution fluorescence lifetime imaging (FLIM)-FRET of HeLa cells to identify protein interactions within the spatiotemporal framework of the cell. We show that autophagosomal syntaxin 17 (Stx17) heterotrimerizes with synaptosome-associated protein 29 (SNAP29) and vesicle-associated membrane protein 7 (VAMP7) in situ, highlighting a functional role for VAMP7 in autophagosome clearance that has previously been sidelined in favor of a role for VAMP8. Additionally, we identified multimodal regulation of SNARE assembly by the Sec1/Munc18 (SM) protein VPS33A, mirroring other syntaxin-SM interactions and therefore suggesting a unified model of SM regulation. Contrary to current theoretical models, we found that the Stx17 N-peptide appears to interact in a positionally conserved, but mechanistically divergent manner with VPS33A, providing a late "go, no-go" step for autophagic fusion via a phosphoserine master-switch. Our findings suggest that Stx17 fusion competency is regulated by a phosphosite in its N-peptide, representing a previously unknown regulatory step in mammalian autophagy.
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Affiliation(s)
- Rebecca S Saleeb
- From the Edinburgh Super-Resolution Imaging Consortium, Institute of Biological Chemistry, Biophysics, and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Deirdre M Kavanagh
- From the Edinburgh Super-Resolution Imaging Consortium, Institute of Biological Chemistry, Biophysics, and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Alison R Dun
- From the Edinburgh Super-Resolution Imaging Consortium, Institute of Biological Chemistry, Biophysics, and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Paul A Dalgarno
- From the Edinburgh Super-Resolution Imaging Consortium, Institute of Biological Chemistry, Biophysics, and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Rory R Duncan
- From the Edinburgh Super-Resolution Imaging Consortium, Institute of Biological Chemistry, Biophysics, and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
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13
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Padmanabhan P, Bademosi AT, Kasula R, Lauwers E, Verstreken P, Meunier FA. Need for speed: Super-resolving the dynamic nanoclustering of syntaxin-1 at exocytic fusion sites. Neuropharmacology 2019; 169:107554. [PMID: 30826343 DOI: 10.1016/j.neuropharm.2019.02.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 02/21/2019] [Accepted: 02/27/2019] [Indexed: 01/08/2023]
Abstract
Communication between cells relies on regulated exocytosis, a multi-step process that involves the docking, priming and fusion of vesicles with the plasma membrane, culminating in the release of neurotransmitters and hormones. Key proteins and lipids involved in exocytosis are subjected to Brownian movement and constantly switch between distinct motion states which are governed by short-lived molecular interactions. Critical biochemical reactions between exocytic proteins that occur in the confinement of nanodomains underpin the precise sequence of priming steps which leads to the fusion of vesicles. The advent of super-resolution microscopy techniques has provided the means to visualize individual molecules on the plasma membrane with high spatiotemporal resolution in live cells. These techniques are revealing a highly dynamic nature of the nanoscale organization of the exocytic machinery. In this review, we focus on soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) syntaxin-1, which mediates vesicular fusion. Syntaxin-1 is highly mobile at the plasma membrane, and its inherent speed allows fast assembly and disassembly of syntaxin-1 nanoclusters which are associated with exocytosis. We reflect on recent studies which have revealed the mechanisms regulating syntaxin-1 nanoclustering on the plasma membrane and draw inferences on the effect of synaptic activity, phosphoinositides, N-ethylmaleimide-sensitive factor (NSF), α-soluble NSF attachment protein (α-SNAP) and SNARE complex assembly on the dynamic nanoscale organization of syntaxin-1. This article is part of the special issue entitled 'Mobility and trafficking of neuronal membrane proteins'.
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Affiliation(s)
- Pranesh Padmanabhan
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland, Australia
| | - Adekunle T Bademosi
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland, Australia
| | - Ravikiran Kasula
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland, Australia
| | - Elsa Lauwers
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Department of Neurosciences and Leuven Brain Institute, KU Leuven, 3000 Leuven, Belgium
| | - Patrik Verstreken
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Department of Neurosciences and Leuven Brain Institute, KU Leuven, 3000 Leuven, Belgium
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland, Australia.
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14
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Stamberger H, Weckhuysen S, De Jonghe P. STXBP1 as a therapeutic target for epileptic encephalopathy. Expert Opin Ther Targets 2017; 21:1027-1036. [DOI: 10.1080/14728222.2017.1386175] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Hannah Stamberger
- Neurogenetics Group, Center for Molecular Neurology, VIB, Antwerp, Belgium
- Laboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
- Department of Neurology, Antwerp University Hospital, Antwerp, Belgium
| | - Sarah Weckhuysen
- Neurogenetics Group, Center for Molecular Neurology, VIB, Antwerp, Belgium
- Laboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
- Department of Neurology, Antwerp University Hospital, Antwerp, Belgium
| | - Peter De Jonghe
- Neurogenetics Group, Center for Molecular Neurology, VIB, Antwerp, Belgium
- Laboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
- Department of Neurology, Antwerp University Hospital, Antwerp, Belgium
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15
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Verboogen DRJ, González Mancha N, Ter Beest M, van den Bogaart G. Fluorescence Lifetime Imaging Microscopy reveals rerouting of SNARE trafficking driving dendritic cell activation. eLife 2017; 6. [PMID: 28524818 PMCID: PMC5473687 DOI: 10.7554/elife.23525] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 05/18/2017] [Indexed: 11/13/2022] Open
Abstract
SNARE proteins play a crucial role in intracellular trafficking by catalyzing membrane fusion, but assigning SNAREs to specific intracellular transport routes is challenging with current techniques. We developed a novel Förster resonance energy transfer-fluorescence lifetime imaging microscopy (FRET-FLIM)-based technique allowing visualization of real-time local interactions of fluorescently tagged SNARE proteins in live cells. We used FRET-FLIM to delineate the trafficking steps underlying the release of the inflammatory cytokine interleukin-6 (IL-6) from human blood-derived dendritic cells. We found that activation of dendritic cells by bacterial lipopolysaccharide leads to increased FRET of fluorescently labeled syntaxin 4 with VAMP3 specifically at the plasma membrane, indicating increased SNARE complex formation, whereas FRET with other tested SNAREs was unaltered. Our results revealed that SNARE complexing is a key regulatory step for cytokine production by immune cells and prove the applicability of FRET-FLIM for visualizing SNARE complexes in live cells with subcellular spatial resolution.
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Affiliation(s)
- Daniëlle Rianne José Verboogen
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Natalia González Mancha
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Martin Ter Beest
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Geert van den Bogaart
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
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16
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Dun AR, Lord GJ, Wilson RS, Kavanagh DM, Cialowicz KI, Sugita S, Park S, Yang L, Smyth AM, Papadopulos A, Rickman C, Duncan RR. Navigation through the Plasma Membrane Molecular Landscape Shapes Random Organelle Movement. Curr Biol 2017; 27:408-414. [PMID: 28089515 PMCID: PMC5300901 DOI: 10.1016/j.cub.2016.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 09/05/2016] [Accepted: 12/02/2016] [Indexed: 12/13/2022]
Abstract
Eukaryotic plasma membrane organization theory has long been controversial, in part due to a dearth of suitably high-resolution techniques to probe molecular architecture in situ and integrate information from diverse data streams [1]. Notably, clustered patterning of membrane proteins is a commonly conserved feature across diverse protein families (reviewed in [2]), including the SNAREs [3], SM proteins [4, 5], ion channels [6, 7], and receptors (e.g., [8]). Much effort has gone into analyzing the behavior of secretory organelles [9-13], and understanding the relationship between the membrane and proximal organelles [4, 5, 12, 14] is an essential goal for cell biology as broad concepts or rules may be established. Here we explore the generally accepted model that vesicles at the plasmalemma are guided by cytoskeletal tracks to specific sites on the membrane that have clustered molecular machinery for secretion [15], organized in part by the local lipid composition [16]. To increase our understanding of these fundamental processes, we integrated nanoscopy and spectroscopy of the secretory machinery with organelle tracking data in a mathematical model, iterating with knockdown cell models. We find that repeated routes followed by successive vesicles, the re-use of similar fusion sites, and the apparently distinct vesicle "pools" are all fashioned by the Brownian behavior of organelles overlaid on navigation between non-reactive secretory protein molecular depots patterned at the plasma membrane.
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Affiliation(s)
- Alison R Dun
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium
| | - Gabriel J Lord
- Department of Mathematics, Maxwell Institute, MACS, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Rhodri S Wilson
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium
| | - Deirdre M Kavanagh
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium
| | - Katarzyna I Cialowicz
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium
| | - Shuzo Sugita
- Toronto Western Research Institute, Room 11-432, McLaughlin Wing, 399 Bathurst St., Toronto, ON M5T 2S8, Canada
| | - Seungmee Park
- Toronto Western Research Institute, Room 11-432, McLaughlin Wing, 399 Bathurst St., Toronto, ON M5T 2S8, Canada
| | - Lei Yang
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium
| | - Annya M Smyth
- Centre for Inflammation Research, University of Edinburgh, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK
| | - Andreas Papadopulos
- The Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Colin Rickman
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium
| | - Rory R Duncan
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium.
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17
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Zhang Y, Cuyt A, Lee WS, Lo Bianco G, Wu G, Chen Y, Li DDU. Towards unsupervised fluorescence lifetime imaging using low dimensional variable projection. OPTICS EXPRESS 2016; 24:26777-26791. [PMID: 27857408 DOI: 10.1364/oe.24.026777] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Analyzing large fluorescence lifetime imaging (FLIM) data is becoming overwhelming; the latest FLIM systems easily produce massive amounts of data, making an efficient analysis more challenging than ever. In this paper we propose the combination of a custom-fit variable projection method, with a Laguerre expansion based deconvolution, to analyze bi-exponential data obtained from time-domain FLIM systems. Unlike nonlinear least squares methods, which require a suitable initial guess from an experienced researcher, the new method is free from manual interventions and hence can support automated analysis. Monte Carlo simulations are carried out on synthesized FLIM data to demonstrate the performance compared to other approaches. The performance is also illustrated on real-life FLIM data obtained from the study of autofluorescence of daisy pollen and the endocytosis of gold nanorods (GNRs) in living cells. In the latter, the fluorescence lifetimes of the GNRs are much shorter than the full width at half maximum of the instrument response function. Overall, our proposed method contains simple steps and shows great promise in realising automated FLIM analysis of large data sets.
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18
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Kasula R, Chai YJ, Bademosi AT, Harper CB, Gormal RS, Morrow IC, Hosy E, Collins BM, Choquet D, Papadopulos A, Meunier FA. The Munc18-1 domain 3a hinge-loop controls syntaxin-1A nanodomain assembly and engagement with the SNARE complex during secretory vesicle priming. J Cell Biol 2016; 214:847-58. [PMID: 27646276 PMCID: PMC5037406 DOI: 10.1083/jcb.201508118] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 08/24/2016] [Indexed: 12/12/2022] Open
Abstract
Kasula et al. use single-molecule imaging to reveal the diffusional signature for the SNARE proteins Munc18-1 and syntaxin-1A during secretory vesicle priming. The authors show that a conformational change in the Munc18-1 domain 3a hinge-loop regulates engagement of syntaxin-1A in the SNARE complex. Munc18-1 and syntaxin-1A control SNARE-dependent neuroexocytosis and are organized in nanodomains on the plasma membrane of neurons and neurosecretory cells. Deciphering the intra- and intermolecular steps via which they prepare secretory vesicles (SVs) for fusion is key to understanding neuronal and hormonal communication. Here, we demonstrate that expression of a priming-deficient mutant lacking 17 residues of the domain 3a hinge-loop (Munc18-1Δ317-333) in PC12 cells engineered to knockdown Munc18-1/2 markedly prolonged SV docking. Single-molecule analysis revealed nonhomogeneous diffusion of Munc18-1 and syntaxin-1A in and out of partially overlapping nanodomains. Whereas Munc18-1WT mobility increased in response to stimulation, syntaxin-1A became less mobile. These Munc18-1 and syntaxin-1A diffusional switches were blocked by the expression of Munc18-1Δ317-333, suggesting that a conformational change in the Munc18-1 hinge-loop controls syntaxin-1A and subsequent SNARE complex assembly. Accordingly, syntaxin-1A confinement was prevented by expression of botulinum neurotoxin type E. The Munc18-1 domain 3a hinge-loop therefore controls syntaxin-1A engagement into SNARE complex formation during priming.
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Affiliation(s)
- Ravikiran Kasula
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Ye Jin Chai
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Adekunle T Bademosi
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Callista B Harper
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Rachel S Gormal
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Isabel C Morrow
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Eric Hosy
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, 33077 Bordeaux, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5297, 33077 Bordeaux, France
| | - Brett M Collins
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Daniel Choquet
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, 33077 Bordeaux, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5297, 33077 Bordeaux, France Bordeaux Imaging Center, Unité Mixte de Service 3420, Centre National de la Recherche Scientifique, US4 Institut National de la Santé et de la Recherche Médicale, University of Bordeaux, 33077 Bordeaux, France
| | - Andreas Papadopulos
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Frédéric A Meunier
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
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19
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Zhang Y, Chen Y, Li DDU. Optimizing Laguerre expansion based deconvolution methods for analysing bi-exponential fluorescence lifetime images. OPTICS EXPRESS 2016; 24:13894-905. [PMID: 27410552 DOI: 10.1364/oe.24.013894] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Fast deconvolution is an essential step to calibrate instrument responses in big fluorescence lifetime imaging microscopy (FLIM) image analysis. This paper examined a computationally effective least squares deconvolution method based on Laguerre expansion (LSD-LE), recently developed for clinical diagnosis applications, and proposed new criteria for selecting Laguerre basis functions (LBFs) without considering the mutual orthonormalities between LBFs. Compared with the previously reported LSD-LE, the improved LSD-LE allows to use a higher laser repetition rate, reducing the acquisition time per measurement. Moreover, we extended it, for the first time, to analyze bi-exponential fluorescence decays for more general FLIM-FRET applications. The proposed method was tested on both synthesized bi-exponential and realistic FLIM data for studying the endocytosis of gold nanorods in Hek293 cells. Compared with the previously reported constrained LSD-LE, it shows promising results.
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20
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Liu S, Sahid MNA, Takemasa E, Kiyoi T, Kuno M, Oshima Y, Maeyama K. CRACM3 regulates the stability of non-excitable exocytotic vesicle fusion pores in a Ca(2+)-independent manner via molecular interaction with syntaxin4. Sci Rep 2016; 6:28133. [PMID: 27301714 PMCID: PMC4908399 DOI: 10.1038/srep28133] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 06/01/2016] [Indexed: 12/31/2022] Open
Abstract
Ca(2+) release-activated calcium channel 3 (CRACM3) is a unique member of the CRAC family of Ca(2+)-selective channels. In a non-excitable exocytosis model, we found that the extracellular L3 domain and the cytoplasmic C-terminus of CRACM3 interacted in an activity-dependent manner with the N-peptide of syntaxin4, a soluble N-ethylmaleimide-sensitive factor attachment receptor protein. Our biochemical, electrophysiological and single-vesicle studies showed that knockdown of CRACM3 suppressed functional exocytosis by decreasing the open time of the vesicle fusion pore without affecting Ca(2+) influx, the activity-dependent membrane capacitance (Cm) change, and the total number of fusion events. Conversely, overexpressing CRACM3 significantly impaired cell exocytosis independent of Ca(2+), led to an impaired Cm change, decreased the number of fusion events, and prolonged the dwell time of the fusion pore. CRACM3 changes the stability of the vesicle fusion pore in a manner consistent with the altered molecular expression. Our findings imply that CRACM3 plays a greater role in exocytosis than simply acting as a compensatory subunit of a Ca(2+) channel.
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Affiliation(s)
- Shuang Liu
- Department of Pharmacology, Ehime University Graduate School of Medicine, Shitsugawa, Toon-shi, Ehime 791-0295, Japan
| | - Muhammad Novrizal Abdi Sahid
- Department of Pharmacology, Ehime University Graduate School of Medicine, Shitsugawa, Toon-shi, Ehime 791-0295, Japan
| | - Erika Takemasa
- Department of Pharmacology, Ehime University Graduate School of Medicine, Shitsugawa, Toon-shi, Ehime 791-0295, Japan
| | - Takeshi Kiyoi
- Department of Bioscience, Integrated Center for Sciences, Ehime University, Shitsukawa, Toon-shi, Ehime, 791-0295, Japan
| | - Miyuki Kuno
- Department of Molecular and Cellular Physiology, Osaka City University Graduate School of Medicine, 1-5-7 Asahimachi, Abeno-ku, Osaka 545-8585, Japan
| | - Yusuke Oshima
- Department of Molecular Medicine for Pathogenesis, Ehime University Graduate School of Medicine, Toon, Ehime 791-0295, Japan
| | - Kazutaka Maeyama
- Department of Pharmacology, Ehime University Graduate School of Medicine, Shitsugawa, Toon-shi, Ehime 791-0295, Japan
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21
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Körber C, Kuner T. Molecular Machines Regulating the Release Probability of Synaptic Vesicles at the Active Zone. Front Synaptic Neurosci 2016; 8:5. [PMID: 26973506 PMCID: PMC4773589 DOI: 10.3389/fnsyn.2016.00005] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 02/17/2016] [Indexed: 11/13/2022] Open
Abstract
The fusion of synaptic vesicles (SVs) with the plasma membrane of the active zone (AZ) upon arrival of an action potential (AP) at the presynaptic compartment is a tightly regulated probabilistic process crucial for information transfer. The probability of a SV to release its transmitter content in response to an AP, termed release probability (Pr), is highly diverse both at the level of entire synapses and individual SVs at a given synapse. Differences in Pr exist between different types of synapses, between synapses of the same type, synapses originating from the same axon and even between different SV subpopulations within the same presynaptic terminal. The Pr of SVs at the AZ is set by a complex interplay of different presynaptic properties including the availability of release-ready SVs, the location of the SVs relative to the voltage-gated calcium channels (VGCCs) at the AZ, the magnitude of calcium influx upon arrival of the AP, the buffering of calcium ions as well as the identity and sensitivity of the calcium sensor. These properties are not only interconnected, but can also be regulated dynamically to match the requirements of activity patterns mediated by the synapse. Here, we review recent advances in identifying molecules and molecular machines taking part in the determination of vesicular Pr at the AZ.
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Affiliation(s)
- Christoph Körber
- Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University Heidelberg, Germany
| | - Thomas Kuner
- Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University Heidelberg, Germany
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22
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Feligioni M, Mango D, Piccinin S, Imbriani P, Iannuzzi F, Caruso A, De Angelis F, Blandini F, Mercuri NB, Pisani A, Nisticò R. Subtle alterations of excitatory transmission are linked to presynaptic changes in the hippocampus of PINK1-deficient mice. Synapse 2016; 70:223-30. [PMID: 26850695 DOI: 10.1002/syn.21894] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 02/01/2016] [Accepted: 02/02/2016] [Indexed: 12/13/2022]
Abstract
Homozygous or heterozygous mutations in the PTEN-induced kinase 1 (PINK1) gene have been linked to early-onset Parkinson's disease (PD). Several neurophysiological studies have demonstrated alterations in striatal synaptic plasticity along with impaired dopamine release in PINK1-deficient mice. Using electrophysiological methods, here we show that PINK1 loss of function causes a progressive increase of spontaneous glutamate-mediated synaptic events in the hippocampus, without influencing long-term potentiation. Moreover, fluorescence analysis reveals increased neurotrasmitter release although our biochemical results failed to detect which presynaptic proteins might be engaged. This study provides a novel role for PINK1 beyond the physiology of nigrostriatal dopaminergic circuit. Specifically, PINK1 might contribute to preserve synaptic function and glutamatergic homeostasis in the hippocampus, a brain region underlying cognition. The subtle changes in excitatory transmission here observed might be a pathogenic precursor to excitotoxic neurodegeneration and cognitive decline often observed in PD. Using electrophysiological and fluorescence techniques, we demonstrate that lack of PINK1 causes increased excitatory transmission and neurotransmitter release in the hippocampus, which might lead to the cognitive decline often observed in Parkinson's disease.
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Affiliation(s)
- Marco Feligioni
- EBRI-European Brain Research Institute, Rome, Italy.,Casa Cura Policlinico, Milan, Italy
| | - Dalila Mango
- EBRI-European Brain Research Institute, Rome, Italy
| | | | | | | | | | | | - Fabio Blandini
- IRCSS "C. Mondino", National Neurological Institute, Pavia, Italy
| | - Nicola B Mercuri
- University of Rome "Tor Vergata", Rome, Italy.,IRCSS Santa Lucia Foundation, Rome, Italy
| | | | - Robert Nisticò
- EBRI-European Brain Research Institute, Rome, Italy.,University of Rome "Tor Vergata", Rome, Italy
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23
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Xiao H, Liu B, Chen Y, Zhang J. Learning, memory and synaptic plasticity in hippocampus in rats exposed to sevoflurane. Int J Dev Neurosci 2015; 48:38-49. [PMID: 26612208 DOI: 10.1016/j.ijdevneu.2015.11.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 11/01/2015] [Accepted: 11/10/2015] [Indexed: 12/30/2022] Open
Abstract
PURPOSE Developmental exposure to volatile anesthetics has been associated with cognitive deficits at adulthood. Rodent studies have revealed impairments in performance in learning tasks involving the hippocampus. However, how the duration of anesthesia exposure impact on hippocampal synaptic plasticity, learning, and memory is as yet not fully elucidated. METHODS On postnatal day 7(P7), rat pups were divided into 3 groups: control group (n=30), 3% sevoflurane treatment for 1h (Sev 1h group, n=30) and 3% sevoflurane treatment for 6h (Sev 6h group, n=28). Following anesthesia, synaptic vesicle-associated proteins and dendrite spine density and synapse ultrastructure were measured using western blotting, Golgi staining, and transmission electron microscopy (TEM) on P21. In addition, the effects of sevoflurane treatment on long-term potentiation (LTP) and long-term depression (LTD), two molecular correlates of memory, were studied in CA1 subfields of the hippocampus, using electrophysiological recordings of field potentials in hippocampal slices on P35-42. Rats' neurocognitive performance was assessed at 2 months of age, using the Morris water maze and novel-object recognition tasks. RESULTS Our results showed that neonatal exposure to 3% sevoflurane for 6h results in reduced spine density of apical dendrites along with elevated expression of synaptic vesicle-associated proteins (SNAP-25 and syntaxin), and synaptic ultrastructure damage in the hippocampus. The electrophysiological evidence indicated that hippocampal LTP, but not LTD, was inhibited and that learning and memory performance were impaired in two behavioral tasks in the Sev 6h group. In contrast, lesser structural and functional damage in the hippocampus was observed in the Sev 1h group. CONCLUSION Our data showed that 6-h exposure of the developing brain to 3% sevoflurane could result in synaptic plasticity impairment in the hippocampus and spatial and nonspatial hippocampal-dependent learning and memory deficits. In contrast, shorter-duration exposure (1h) results in less damage. These results provide further evidences that duration of anesthesia exposure could have differential effects on neuronal plasticity and neurocognitive performance.
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Affiliation(s)
- Hongyan Xiao
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai, China.
| | - Bing Liu
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai, China.
| | - Yali Chen
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai, China.
| | - Jun Zhang
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai, China.
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