101
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Burn GL, Cornish GH, Potrzebowska K, Samuelsson M, Griffié J, Minoughan S, Yates M, Ashdown G, Pernodet N, Morrison VL, Sanchez-Blanco C, Purvis H, Clarke F, Brownlie RJ, Vyse TJ, Zamoyska R, Owen DM, Svensson LM, Cope AP. Superresolution imaging of the cytoplasmic phosphatase PTPN22 links integrin-mediated T cell adhesion with autoimmunity. Sci Signal 2016; 9:ra99. [PMID: 27703032 DOI: 10.1126/scisignal.aaf2195] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Integrins are heterodimeric transmembrane proteins that play a fundamental role in the migration of leukocytes to sites of infection or injury. We found that protein tyrosine phosphatase nonreceptor type 22 (PTPN22) inhibits signaling by the integrin lymphocyte function-associated antigen-1 (LFA-1) in effector T cells. PTPN22 colocalized with its substrates at the leading edge of cells migrating on surfaces coated with the LFA-1 ligand intercellular adhesion molecule-1 (ICAM-1). Knockout or knockdown of PTPN22 or expression of the autoimmune disease-associated PTPN22-R620W variant resulted in the enhanced phosphorylation of signaling molecules downstream of integrins. Superresolution imaging revealed that PTPN22-R620 (wild-type PTPN22) was present as large clusters in unstimulated T cells and that these disaggregated upon stimulation of LFA-1, enabling increased association of PTPN22 with its binding partners at the leading edge. The failure of PTPN22-R620W molecules to be retained at the leading edge led to increased LFA-1 clustering and integrin-mediated cell adhesion. Our data define a previously uncharacterized mechanism for fine-tuning integrin signaling in T cells, as well as a paradigm of autoimmunity in humans in which disease susceptibility is underpinned by inherited phosphatase mutations that perturb integrin function.
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Affiliation(s)
- Garth L Burn
- Academic Department of Rheumatology, Centre for Molecular and Cellular Biology of Inflammation, Faculty of Life Sciences and Medicine, King's College London, London SE1 1UL, U.K
| | - Georgina H Cornish
- Academic Department of Rheumatology, Centre for Molecular and Cellular Biology of Inflammation, Faculty of Life Sciences and Medicine, King's College London, London SE1 1UL, U.K
| | | | - Malin Samuelsson
- Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
| | - Juliette Griffié
- Department of Physics and Randall Division of Cell and Molecular Biophysics, Faculty of Life Sciences and Medicine, King's College London, London SE1 1UL, U.K
| | - Sophie Minoughan
- Department of Physics and Randall Division of Cell and Molecular Biophysics, Faculty of Life Sciences and Medicine, King's College London, London SE1 1UL, U.K
| | - Mark Yates
- Academic Department of Rheumatology, Centre for Molecular and Cellular Biology of Inflammation, Faculty of Life Sciences and Medicine, King's College London, London SE1 1UL, U.K
| | - George Ashdown
- Department of Physics and Randall Division of Cell and Molecular Biophysics, Faculty of Life Sciences and Medicine, King's College London, London SE1 1UL, U.K
| | - Nicolas Pernodet
- Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden
| | - Vicky L Morrison
- Institute of Immunology, Infection and Inflammation, University of Glasgow, Glasgow G12 8TA, U.K
| | - Cristina Sanchez-Blanco
- Academic Department of Rheumatology, Centre for Molecular and Cellular Biology of Inflammation, Faculty of Life Sciences and Medicine, King's College London, London SE1 1UL, U.K
| | - Harriet Purvis
- Academic Department of Rheumatology, Centre for Molecular and Cellular Biology of Inflammation, Faculty of Life Sciences and Medicine, King's College London, London SE1 1UL, U.K
| | - Fiona Clarke
- Academic Department of Rheumatology, Centre for Molecular and Cellular Biology of Inflammation, Faculty of Life Sciences and Medicine, King's College London, London SE1 1UL, U.K
| | - Rebecca J Brownlie
- Institute of Immunology and Infection Research, Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh EH9 3FL, U.K
| | - Timothy J Vyse
- Department of Medical and Molecular Genetics, Faculty of Life Sciences and Medicine, King's College London, London SE1 9RT, U.K
| | - Rose Zamoyska
- Institute of Immunology and Infection Research, Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh EH9 3FL, U.K
| | - Dylan M Owen
- Department of Physics and Randall Division of Cell and Molecular Biophysics, Faculty of Life Sciences and Medicine, King's College London, London SE1 1UL, U.K
| | - Lena M Svensson
- Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden.
| | - Andrew P Cope
- Academic Department of Rheumatology, Centre for Molecular and Cellular Biology of Inflammation, Faculty of Life Sciences and Medicine, King's College London, London SE1 1UL, U.K.
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102
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Githaka JM, Vega AR, Baird MA, Davidson MW, Jaqaman K, Touret N. Ligand-induced growth and compaction of CD36 nanoclusters enriched in Fyn induces Fyn signaling. J Cell Sci 2016; 129:4175-4189. [PMID: 27694211 DOI: 10.1242/jcs.188946] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 09/20/2016] [Indexed: 12/30/2022] Open
Abstract
Nanoclustering is an emerging organizational principle for membrane-associated proteins. The functional consequences of nanoclustering for receptor signaling remain largely unknown. Here, we applied quantitative multi-channel high- and super-resolution imaging to analyze the endothelial cell surface receptor CD36, the clustering of which upon binding to multivalent ligands, such as the anti-angiogenic factor thrombospondin-1 (TSP-1), is thought to be crucial for signaling. We found that a substantial fraction of unligated CD36 exists in nanoclusters, which not only promote TSP-1 binding but are also enriched with the downstream effector Fyn. Exposure to multivalent ligands (TSP-1 or anti-CD36 IgM) that result in larger and denser CD36 clusters activates Fyn. Conversely, pharmacological perturbations that prevent the enhancement of CD36 clustering by TSP-1 abrogate Fyn activation. In both cases, there is no detectable change in Fyn enrichment at CD36 nanoclusters. These observations reveal a crucial role for the basal organization of a receptor into nanoclusters that are enriched with the signal-transducing downstream effectors of that receptor, such that enhancement of clustering by multivalent ligands is necessary and sufficient to activate the downstream effector without the need for its de novo recruitment.
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Affiliation(s)
- John Maringa Githaka
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Anthony R Vega
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Michelle A Baird
- National High Magnetic Field Laboratory and Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Michael W Davidson
- National High Magnetic Field Laboratory and Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Khuloud Jaqaman
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Nicolas Touret
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
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103
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Mateos-Gil P, Letschert S, Doose S, Sauer M. Super-Resolution Imaging of Plasma Membrane Proteins with Click Chemistry. Front Cell Dev Biol 2016; 4:98. [PMID: 27668214 PMCID: PMC5016519 DOI: 10.3389/fcell.2016.00098] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 08/24/2016] [Indexed: 12/30/2022] Open
Abstract
Besides its function as a passive cell wall, the plasma membrane (PM) serves as a platform for different physiological processes such as signal transduction and cell adhesion, determining the ability of cells to communicate with the exterior, and form tissues. Therefore, the spatial distribution of PM components, and the molecular mechanisms underlying it, have important implications in various biological fields including cell development, neurobiology, and immunology. The existence of confined compartments in the plasma membrane that vary on many length scales from protein multimers to micrometer-size domains with different protein and lipid composition is today beyond all questions. As much as the physiology of cells is controlled by the spatial organization of PM components, the study of distribution, size, and composition remains challenging. Visualization of the molecular distribution of PM components has been impeded mainly due to two problems: the specific labeling of lipids and proteins without perturbing their native distribution and the diffraction-limit of fluorescence microscopy restricting the resolution to about half the wavelength of light. Here, we present a bioorthogonal chemical reporter strategy based on click chemistry and metabolic labeling for efficient and specific visualization of PM proteins and glycans with organic fluorophores in combination with super-resolution fluorescence imaging by direct stochastic optical reconstruction microscopy (dSTORM) with single-molecule sensitivity.
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Affiliation(s)
- Pablo Mateos-Gil
- Department of Biotechnology and Biophysics, Julius Maximilian University of Würzburg Würzburg, Germany
| | - Sebastian Letschert
- Department of Biotechnology and Biophysics, Julius Maximilian University of Würzburg Würzburg, Germany
| | - Sören Doose
- Department of Biotechnology and Biophysics, Julius Maximilian University of Würzburg Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Julius Maximilian University of Würzburg Würzburg, Germany
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104
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Functional role of T-cell receptor nanoclusters in signal initiation and antigen discrimination. Proc Natl Acad Sci U S A 2016; 113:E5454-63. [PMID: 27573839 DOI: 10.1073/pnas.1607436113] [Citation(s) in RCA: 145] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Antigen recognition by the T-cell receptor (TCR) is a hallmark of the adaptive immune system. When the TCR engages a peptide bound to the restricting major histocompatibility complex molecule (pMHC), it transmits a signal via the associated CD3 complex. How the extracellular antigen recognition event leads to intracellular phosphorylation remains unclear. Here, we used single-molecule localization microscopy to quantify the organization of TCR-CD3 complexes into nanoscale clusters and to distinguish between triggered and nontriggered TCR-CD3 complexes. We found that only TCR-CD3 complexes in dense clusters were phosphorylated and associated with downstream signaling proteins, demonstrating that the molecular density within clusters dictates signal initiation. Moreover, both pMHC dose and TCR-pMHC affinity determined the density of TCR-CD3 clusters, which scaled with overall phosphorylation levels. Thus, TCR-CD3 clustering translates antigen recognition by the TCR into signal initiation by the CD3 complex, and the formation of dense signaling-competent clusters is a process of antigen discrimination.
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105
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Shivanandan A, Unnikrishnan J, Radenovic A. On characterizing protein spatial clusters with correlation approaches. Sci Rep 2016; 6:31164. [PMID: 27507257 PMCID: PMC4979030 DOI: 10.1038/srep31164] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 07/15/2016] [Indexed: 12/31/2022] Open
Abstract
Spatial aggregation of proteins might have functional importance, e.g., in signaling, and nano-imaging can be used to study them. Such studies require accurate characterization of clusters based on noisy data. A set of spatial correlation approaches free of underlying cluster processes and input parameters have been widely used for this purpose. They include the radius of maximal aggregation ra obtained from Ripley’s L(r) − r function as an estimator of cluster size, and the estimation of various cluster parameters based on an exponential model of the Pair Correlation Function(PCF). While convenient, the accuracy of these methods is not clear: e.g., does it depend on how the molecules are distributed within the clusters, or on cluster parameters? We analyze these methods for a variety of cluster models. We find that ra relates to true cluster size by a factor that is nonlinearly dependent on parameters and that can be arbitrarily large. For the PCF method, for the models analyzed, we obtain linear relationships between the estimators and true parameters, and the estimators were found to be within ±100% of true parameters, depending on the model. Our results, based on an extendable general framework, point to the need for caution in applying these methods.
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Affiliation(s)
- Arun Shivanandan
- Laboratory of Nanoscale Biology, Institute of Bioengineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Jayakrishnan Unnikrishnan
- Audiovisual Communications Laboratory, School of Computer and Communication Sciences, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Aleksandra Radenovic
- Laboratory of Nanoscale Biology, Institute of Bioengineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne 1015, Switzerland
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106
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Lou J, Rossy J, Deng Q, Pageon SV, Gaus K. New Insights into How Trafficking Regulates T Cell Receptor Signaling. Front Cell Dev Biol 2016; 4:77. [PMID: 27508206 PMCID: PMC4960267 DOI: 10.3389/fcell.2016.00077] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 07/11/2016] [Indexed: 02/04/2023] Open
Abstract
There is emerging evidence that exocytosis plays an important role in regulating T cell receptor (TCR) signaling. The trafficking molecules involved in lytic granule (LG) secretion in cytotoxic T lymphocytes (CTL) have been well-studied due to the immune disorder known as familial hemophagocytic lymphohistiocytosis (FHLH). However, the knowledge of trafficking machineries regulating the exocytosis of receptors and signaling molecules remains quite limited. In this review, we summarize the reported trafficking molecules involved in the transport of the TCR and downstream signaling molecules to the cell surface. By combining this information with the known knowledge of LG exocytosis and general exocytic trafficking machinery, we attempt to draw a more complete picture of how the TCR signaling network and exocytic trafficking matrix are interconnected to facilitate T cell activation. This also highlights how membrane compartmentalization facilitates the spatiotemporal organization of cellular responses that are essential for immune functions.
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Affiliation(s)
- Jieqiong Lou
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South WalesSydney, NSW, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of New South WalesSydney, NSW, Australia
| | - Jérémie Rossy
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South WalesSydney, NSW, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of New South WalesSydney, NSW, Australia
| | - Qiji Deng
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South WalesSydney, NSW, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of New South WalesSydney, NSW, Australia
| | - Sophie V Pageon
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South WalesSydney, NSW, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of New South WalesSydney, NSW, Australia
| | - Katharina Gaus
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South WalesSydney, NSW, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of New South WalesSydney, NSW, Australia
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107
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Gooding JJ, Gaus K. Single‐Molecule Sensors: Challenges and Opportunities for Quantitative Analysis. Angew Chem Int Ed Engl 2016; 55:11354-66. [DOI: 10.1002/anie.201600495] [Citation(s) in RCA: 183] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Revised: 04/17/2016] [Indexed: 11/09/2022]
Affiliation(s)
- J. Justin Gooding
- The University of New South Wales School of Chemistry, Australian Centre for NanoMedicine and ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, UNSW Sydney 2052 Australia
| | - Katharina Gaus
- The University of New South Wales EMBL Australia Node in Single Molecule Science ARC Centre of Excellence in Advanced Molecular Imaging Sydney 2052 Australia
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108
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Gooding JJ, Gaus K. Einzelmolekül‐Sensoren: Herausforderungen und Möglichkeiten für die quantitative Analyse. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201600495] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- J. Justin Gooding
- The University of New South Wales School of Chemistry, Australian Centre for NanoMedicine and ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, UNSW Sydney 2052 Australien
| | - Katharina Gaus
- The University of New South Wales EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging,UNSW Sydney 2052 Australien
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109
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Sherman E. Resolving protein interactions and organization downstream the T cell antigen receptor using single-molecule localization microscopy: a review. Methods Appl Fluoresc 2016. [DOI: 10.1088/2050-6120/4/2/022002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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110
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Abstract
Cytotoxic T lymphocytes (CTLs) kill virus-infected and tumour cells with remarkable specificity. Upon recognition, CTLs form a cytolytic immune synapse with their target cell, and marked reorganization of both the actin and the microtubule cytoskeletons brings the centrosome up to the plasma membrane to the point of T cell receptor signalling. Secretory granules move towards the centrosome and are delivered to this focal point of secretion. Such centrosomal docking at the plasma membrane also occurs during ciliogenesis; indeed, striking similarities exist between the cytolytic synapse and the primary cilium that throw light on the possible origins of immune synapses.
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Affiliation(s)
- Maike de la Roche
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
- CRUK-Cambridge Research Institute, Cambridge CB2 0RE, UK
| | - Yukako Asano
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Gillian M Griffiths
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
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111
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Abstract
More than 60 Rab GTPases exist in the human genome to regulate vesicle trafficking between organelles. Rab GTPases are members of the Ras GTPase superfamily that broadly control budding, uncoating, motility and fusion of vesicles in most cell types. Rab proteins interconvert between active, GTP-bound form and inactive, GDP-bound form. In their active conformation, they interact with various effector molecules to carry out diverse functions. Rab GTPases are usually small containing only a GTPase domain with a C-terminal prenylation site for membrane anchoring. Recently, we identified a large G protein, CRACR2A (CRAC channel regulator 2A), which uncovers novel functions of Rab GTPases. First, CRACR2A encodes a large Rab GTPase containing multiple functional domains contrary to small Rab GTPases. Second, CRACR2A plays an unexpected role in regulating intracellular signaling pathways important for T cell activation, unlike the canonical role of small Rab GTPases. Vesicles containing CRACR2A bud out from the proximal Golgi area and translocate into the immunological synapse to activate these signaling pathways. Third, instead of recycling, CRACR2A is consumed by a unidirectional pathway. These events are sequentially regulated by prenylation, GTP binding, protein interaction with a signaling adaptor Vav1, and degradation. Together, our findings reveal a novel function of a large Rab GTPase in intracellular signaling pathways, which may be shared by other large Rab GTPases, Rab44 and Rab45.
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Affiliation(s)
- Sonal Srikanth
- a Department of Physiology , David Geffen School of Medicine, UCLA , Los Angeles , CA , USA
| | - Jin Seok Woo
- a Department of Physiology , David Geffen School of Medicine, UCLA , Los Angeles , CA , USA
| | - Yousang Gwack
- a Department of Physiology , David Geffen School of Medicine, UCLA , Los Angeles , CA , USA
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112
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Oszmiana A, Williamson DJ, Cordoba SP, Morgan DJ, Kennedy PR, Stacey K, Davis DM. The Size of Activating and Inhibitory Killer Ig-like Receptor Nanoclusters Is Controlled by the Transmembrane Sequence and Affects Signaling. Cell Rep 2016; 15:1957-72. [PMID: 27210755 PMCID: PMC4893158 DOI: 10.1016/j.celrep.2016.04.075] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 03/15/2016] [Accepted: 04/20/2016] [Indexed: 01/24/2023] Open
Abstract
Super-resolution microscopy has revealed that immune cell receptors are organized in nanoscale clusters at cell surfaces and immune synapses. However, mechanisms and functions for this nanoscale organization remain unclear. Here, we used super-resolution microscopy to compare the surface organization of paired killer Ig-like receptors (KIR), KIR2DL1 and KIR2DS1, on human primary natural killer cells and cell lines. Activating KIR2DS1 assembled in clusters two-fold larger than its inhibitory counterpart KIR2DL1. Site-directed mutagenesis established that the size of nanoclusters is controlled by transmembrane amino acid 233, a lysine in KIR2DS1. Super-resolution microscopy also revealed two ways in which the nanoscale clustering of KIR affects signaling. First, KIR2DS1 and DAP12 nanoclusters are juxtaposed in the resting cell state but coalesce upon receptor ligation. Second, quantitative super-resolution microscopy revealed that phosphorylation of the kinase ZAP-70 or phosphatase SHP-1 is favored in larger KIR nanoclusters. Thus, the size of KIR nanoclusters depends on the transmembrane sequence and affects downstream signaling. Activating and inhibitory NK cell receptors have a distinct nanoscale organization The transmembrane sequence of KIR controls their nanoscale organization Nanoclusters of KIR2DS1 and its adaptor are juxtaposed but mix upon activation Phosphorylation of ZAP-70 or SHP-1 is favored in larger receptor nanoclusters
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Affiliation(s)
- Anna Oszmiana
- Manchester Collaborative Centre for Inflammation Research, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK
| | - David J Williamson
- Manchester Collaborative Centre for Inflammation Research, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK
| | - Shaun-Paul Cordoba
- Division of Cell and Molecular Biology, Sir Alexander Fleming Building, Imperial College London, London SW7 2AZ, UK
| | - David J Morgan
- Manchester Collaborative Centre for Inflammation Research, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK
| | - Philippa R Kennedy
- Manchester Collaborative Centre for Inflammation Research, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK
| | - Kevin Stacey
- Manchester Collaborative Centre for Inflammation Research, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK
| | - Daniel M Davis
- Manchester Collaborative Centre for Inflammation Research, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK.
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113
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Halova I, Draber P. Tetraspanins and Transmembrane Adaptor Proteins As Plasma Membrane Organizers-Mast Cell Case. Front Cell Dev Biol 2016; 4:43. [PMID: 27243007 PMCID: PMC4861716 DOI: 10.3389/fcell.2016.00043] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 04/25/2016] [Indexed: 12/16/2022] Open
Abstract
The plasma membrane contains diverse and specialized membrane domains, which include tetraspanin-enriched domains (TEMs) and transmembrane adaptor protein (TRAP)-enriched domains. Recent biophysical, microscopic, and functional studies indicated that TEMs and TRAP-enriched domains are involved in compartmentalization of physicochemical events of such important processes as immunoreceptor signal transduction and chemotaxis. Moreover, there is evidence of a cross-talk between TEMs and TRAP-enriched domains. In this review we discuss the presence and function of such domains and their crosstalk using mast cells as a model. The combined data based on analysis of selected mast cell-expressed tetraspanins [cluster of differentiation (CD)9, CD53, CD63, CD81, CD151)] or TRAPs [linker for activation of T cells (LAT), non-T cell activation linker (NTAL), and phosphoprotein associated with glycosphingolipid-enriched membrane microdomains (PAG)] using knockout mice or specific antibodies point to a diversity within these two families and bring evidence of the important roles of these molecules in signaling events. An example of this diversity is physical separation of two TRAPs, LAT and NTAL, which are in many aspects similar but show plasma membrane location in different microdomains in both non-activated and activated cells. Although our understanding of TEMs and TRAP-enriched domains is far from complete, pharmaceutical applications of the knowledge about these domains are under way.
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Affiliation(s)
- Ivana Halova
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic Prague, Czech Republic
| | - Petr Draber
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic Prague, Czech Republic
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114
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Sergé A. The Molecular Architecture of Cell Adhesion: Dynamic Remodeling Revealed by Videonanoscopy. Front Cell Dev Biol 2016; 4:36. [PMID: 27200348 PMCID: PMC4854873 DOI: 10.3389/fcell.2016.00036] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 04/18/2016] [Indexed: 12/20/2022] Open
Abstract
The plasma membrane delimits the cell, which is the basic unit of living organisms, and is also a privileged site for cell communication with the environment. Cell adhesion can occur through cell-cell and cell-matrix contacts. Adhesion proteins such as integrins and cadherins also constitute receptors for inside-out and outside-in signaling within proteolipidic platforms. Adhesion molecule targeting and stabilization relies on specific features such as preferential segregation by the sub-membrane cytoskeleton meshwork and within membrane proteolipidic microdomains. This review presents an overview of the recent insights brought by the latest developments in microscopy, to unravel the molecular remodeling occurring at cell contacts. The dynamic aspect of cell adhesion was recently highlighted by super-resolution videomicroscopy, also named videonanoscopy. By circumventing the diffraction limit of light, nanoscopy has allowed the monitoring of molecular localization and behavior at the single-molecule level, on fixed and living cells. Accessing molecular-resolution details such as quantitatively monitoring components entering and leaving cell contacts by lateral diffusion and reversible association has revealed an unexpected plasticity. Adhesion structures can be highly specialized, such as focal adhesion in motile cells, as well as immune and neuronal synapses. Spatiotemporal reorganization of adhesion molecules, receptors, and adaptors directly relates to structure/function modulation. Assembly of these supramolecular complexes is continuously balanced by dynamic events, remodeling adhesions on various timescales, notably by molecular conformation switches, lateral diffusion within the membrane and endo/exocytosis. Pathological alterations in cell adhesion are involved in cancer evolution, through cancer stem cell interaction with stromal niches, growth, extravasation, and metastasis.
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Affiliation(s)
- Arnauld Sergé
- Centre de Cancérologie de Marseille, Équipe "Interactions Leuco/Stromales", Institut Paoli-Calmettes, Institut National de la Santé et de la Recherche Médicale U1068, Centre National de la Recherche Scientifique UMR7258, Aix-Marseille Université UM105 Marseille, France
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115
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Su X, Ditlev JA, Hui E, Xing W, Banjade S, Okrut J, King DS, Taunton J, Rosen MK, Vale RD. Phase separation of signaling molecules promotes T cell receptor signal transduction. Science 2016; 352:595-9. [PMID: 27056844 DOI: 10.1126/science.aad9964] [Citation(s) in RCA: 772] [Impact Index Per Article: 96.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 03/23/2016] [Indexed: 12/24/2022]
Abstract
Activation of various cell surface receptors triggers the reorganization of downstream signaling molecules into micrometer- or submicrometer-sized clusters. However, the functional consequences of such clustering have been unclear. We biochemically reconstituted a 12-component signaling pathway on model membranes, beginning with T cell receptor (TCR) activation and ending with actin assembly. When TCR phosphorylation was triggered, downstream signaling proteins spontaneously separated into liquid-like clusters that promoted signaling outputs both in vitro and in human Jurkat T cells. Reconstituted clusters were enriched in kinases but excluded phosphatases and enhanced actin filament assembly by recruiting and organizing actin regulators. These results demonstrate that protein phase separation can create a distinct physical and biochemical compartment that facilitates signaling.
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Affiliation(s)
- Xiaolei Su
- Howard Hughes Medical Institute (HHMI) Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA. Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute, University of California, San Francisco, CA 94158, USA
| | - Jonathon A Ditlev
- Howard Hughes Medical Institute (HHMI) Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA. Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Enfu Hui
- Howard Hughes Medical Institute (HHMI) Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA. Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute, University of California, San Francisco, CA 94158, USA
| | - Wenmin Xing
- Howard Hughes Medical Institute (HHMI) Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA. Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sudeep Banjade
- Howard Hughes Medical Institute (HHMI) Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA. Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Julia Okrut
- Howard Hughes Medical Institute (HHMI) Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA. Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute, University of California, San Francisco, CA 94158, USA
| | - David S King
- HHMI Mass Spectrometry Laboratory and Department of Molecular and Cellular Biology, University of California, Berkeley, CA 94720, USA
| | - Jack Taunton
- Howard Hughes Medical Institute (HHMI) Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA. Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute, University of California, San Francisco, CA 94158, USA
| | - Michael K Rosen
- Howard Hughes Medical Institute (HHMI) Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA. Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Ronald D Vale
- Howard Hughes Medical Institute (HHMI) Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA. Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute, University of California, San Francisco, CA 94158, USA.
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116
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Srikanth S, Kim KD, Gao Y, Woo JS, Ghosh S, Calmettes G, Paz A, Abramson J, Jiang M, Gwack Y. A large Rab GTPase encoded by CRACR2A is a component of subsynaptic vesicles that transmit T cell activation signals. Sci Signal 2016; 9:ra31. [PMID: 27016526 DOI: 10.1126/scisignal.aac9171] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
More than 60 members of the Rab family of guanosine triphosphatases (GTPases) exist in the human genome. Rab GTPases are small proteins that are primarily involved in the formation, trafficking, and fusion of vesicles. We showed thatCRACR2A(Ca(2+) release-activated Ca(2+) channel regulator 2A) encodes a lymphocyte-specific large Rab GTPase that contains multiple functional domains, including EF-hand motifs, a proline-rich domain (PRD), and a Rab GTPase domain with an unconventional prenylation site. Through experiments involving gene silencing in cells and knockout mice, we demonstrated a role for CRACR2A in the activation of the Ca(2+) and c-Jun N-terminal kinase signaling pathways in response to T cell receptor (TCR) stimulation. Vesicles containing this Rab GTPase translocated from near the Golgi to the immunological synapse formed between a T cell and a cognate antigen-presenting cell to activate these signaling pathways. The interaction between the PRD of CRACR2A and the guanidine nucleotide exchange factor Vav1 was required for the accumulation of these vesicles at the immunological synapse. Furthermore, we demonstrated that GTP binding and prenylation of CRACR2A were associated with its localization near the Golgi and its stability. Our findings reveal a previously uncharacterized function of a large Rab GTPase and vesicles near the Golgi in TCR signaling. Other GTPases with similar domain architectures may have similar functions in T cells.
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Affiliation(s)
- Sonal Srikanth
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.
| | - Kyun-Do Kim
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Yuanyuan Gao
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Jin Seok Woo
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Shubhamoy Ghosh
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Guillaume Calmettes
- Department of Medicine (Cardiology), David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA
| | - Aviv Paz
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Jeff Abramson
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Meisheng Jiang
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA
| | - Yousang Gwack
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.
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117
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Tran J, Magenau A, Rodriguez M, Rentero C, Royo T, Enrich C, Thomas SR, Grewal T, Gaus K. Activation of Endothelial Nitric Oxide (eNOS) Occurs through Different Membrane Domains in Endothelial Cells. PLoS One 2016; 11:e0151556. [PMID: 26977592 PMCID: PMC4792450 DOI: 10.1371/journal.pone.0151556] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Accepted: 03/01/2016] [Indexed: 11/18/2022] Open
Abstract
Endothelial cells respond to a large range of stimuli including circulating lipoproteins, growth factors and changes in haemodynamic mechanical forces to regulate the activity of endothelial nitric oxide synthase (eNOS) and maintain blood pressure. While many signalling pathways have been mapped, the identities of membrane domains through which these signals are transmitted are less well characterized. Here, we manipulated bovine aortic endothelial cells (BAEC) with cholesterol and the oxysterol 7-ketocholesterol (7KC). Using a range of microscopy techniques including confocal, 2-photon, super-resolution and electron microscopy, we found that sterol enrichment had differential effects on eNOS and caveolin-1 (Cav1) colocalisation, membrane order of the plasma membrane, caveolae numbers and Cav1 clustering. We found a correlation between cholesterol-induced condensation of the plasma membrane and enhanced high density lipoprotein (HDL)-induced eNOS activity and phosphorylation suggesting that cholesterol domains, but not individual caveolae, mediate HDL stimulation of eNOS. Vascular endothelial growth factor (VEGF)-induced and shear stress-induced eNOS activity was relatively independent of membrane order and may be predominantly controlled by the number of caveolae on the cell surface. Taken together, our data suggest that signals that activate and phosphorylate eNOS are transmitted through distinct membrane domains in endothelial cells.
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Affiliation(s)
- Jason Tran
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, Australia
- ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, Australia
| | - Astrid Magenau
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, Australia
- ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, Australia
| | - Macarena Rodriguez
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, Australia
- ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, Australia
| | - Carles Rentero
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - Teresa Royo
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
- Centre de Recerca Biomèdica CELLEX, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Carlos Enrich
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
- Centre de Recerca Biomèdica CELLEX, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Shane R. Thomas
- School of Medical Sciences, The University of New South Wales, Sydney, Australia
| | - Thomas Grewal
- Faculty of Pharmacy A15, University of Sydney, Sydney, Australia
| | - Katharina Gaus
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, Australia
- ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, Australia
- * E-mail:
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118
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Abstract
T-cell protein microclusters have until recently been investigable only as microscale entities with their composition and structure being discerned by biochemistry or diffraction-limited light microscopy. With the advent of super resolution microscopy comes the ability to interrogate the structure and function of these clusters at the single molecule level by producing highly accurate pointillist maps of single molecule locations at ~20nm resolution. Analysis tools have also been developed to provide rich descriptors of the pointillist data, allowing us to pose questions about the nanoscale organization which governs the local and cell wide responses required of a migratory T-cell.
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119
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Torreno-Pina JA, Manzo C, Salio M, Aichinger MC, Oddone A, Lakadamyali M, Shepherd D, Besra GS, Cerundolo V, Garcia-Parajo MF. The actin cytoskeleton modulates the activation of iNKT cells by segregating CD1d nanoclusters on antigen-presenting cells. Proc Natl Acad Sci U S A 2016; 113:E772-81. [PMID: 26798067 PMCID: PMC4760795 DOI: 10.1073/pnas.1514530113] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Invariant natural killer T (iNKT) cells recognize endogenous and exogenous lipid antigens presented in the context of CD1d molecules. The ability of iNKT cells to recognize endogenous antigens represents a distinct immune recognition strategy, which underscores the constitutive memory phenotype of iNKT cells and their activation during inflammatory conditions. However, the mechanisms regulating such "tonic" activation of iNKT cells remain unclear. Here, we show that the spatiotemporal distribution of CD1d molecules on the surface of antigen-presenting cells (APCs) modulates activation of iNKT cells. By using superresolution microscopy, we show that CD1d molecules form nanoclusters at the cell surface of APCs, and their size and density are constrained by the actin cytoskeleton. Dual-color single-particle tracking revealed that diffusing CD1d nanoclusters are actively arrested by the actin cytoskeleton, preventing their further coalescence. Formation of larger nanoclusters occurs in the absence of interactions between CD1d cytosolic tail and the actin cytoskeleton and correlates with enhanced iNKT cell activation. Importantly and consistently with iNKT cell activation during inflammatory conditions, exposure of APCs to the Toll-like receptor 7/8 agonist R848 increases nanocluster density and iNKT cell activation. Overall, these results define a previously unidentified mechanism that modulates iNKT cell autoreactivity based on the tight control by the APC cytoskeleton of the sizes and densities of endogenous antigen-loaded CD1d nanoclusters.
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Affiliation(s)
- Juan A Torreno-Pina
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Barcelona, Spain
| | - Carlo Manzo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Barcelona, Spain
| | - Mariolina Salio
- Medical Research Council (MRC) Human Immunology Unit, Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom
| | - Michael C Aichinger
- Medical Research Council (MRC) Human Immunology Unit, Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom
| | - Anna Oddone
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Barcelona, Spain
| | - Melike Lakadamyali
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Barcelona, Spain
| | - Dawn Shepherd
- Medical Research Council (MRC) Human Immunology Unit, Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom
| | - Gurdyal S Besra
- School of Biosciences, University of Birmingham, Birmingham B11 2TT, United Kingdom
| | - Vincenzo Cerundolo
- Medical Research Council (MRC) Human Immunology Unit, Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom;
| | - Maria F Garcia-Parajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
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120
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Niedergang F, Di Bartolo V, Alcover A. Comparative Anatomy of Phagocytic and Immunological Synapses. Front Immunol 2016; 7:18. [PMID: 26858721 PMCID: PMC4729869 DOI: 10.3389/fimmu.2016.00018] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 01/14/2016] [Indexed: 11/17/2022] Open
Abstract
The generation of phagocytic cups and immunological synapses are crucial events of the innate and adaptive immune responses, respectively. They are triggered by distinct immune receptors and performed by different cell types. However, growing experimental evidence shows that a very close series of molecular and cellular events control these two processes. Thus, the tight and dynamic interplay between receptor signaling, actin and microtubule cytoskeleton, and targeted vesicle traffic are all critical features to build functional phagosomes and immunological synapses. Interestingly, both phagocytic cups and immunological synapses display particular spatial and temporal patterns of receptors and signaling molecules, leading to the notion of “phagocytic synapse.” Here, we discuss both types of structures, their organization, and the mechanisms by which they are generated and regulated.
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Affiliation(s)
- Florence Niedergang
- U1016, Institut Cochin, INSERM, Paris, France; UMR 8104, CNRS, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Vincenzo Di Bartolo
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, Paris, France; U1221, INSERM, Paris, France
| | - Andrés Alcover
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, Paris, France; U1221, INSERM, Paris, France
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121
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Harper CB, Papadopulos A, Martin S, Matthews DR, Morgan GP, Nguyen TH, Wang T, Nair D, Choquet D, Meunier FA. Botulinum neurotoxin type-A enters a non-recycling pool of synaptic vesicles. Sci Rep 2016; 6:19654. [PMID: 26805017 PMCID: PMC4726273 DOI: 10.1038/srep19654] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 11/20/2015] [Indexed: 02/03/2023] Open
Abstract
Neuronal communication relies on synaptic vesicles undergoing regulated exocytosis and recycling for multiple rounds of fusion. Whether all synaptic vesicles have identical protein content has been challenged, suggesting that their recycling ability may differ greatly. Botulinum neurotoxin type-A (BoNT/A) is a highly potent neurotoxin that is internalized in synaptic vesicles at motor nerve terminals and induces flaccid paralysis. Recently, BoNT/A was also shown to undergo retrograde transport, suggesting it might enter a specific pool of synaptic vesicles with a retrograde trafficking fate. Using high-resolution microscopy techniques including electron microscopy and single molecule imaging, we found that the BoNT/A binding domain is internalized within a subset of vesicles that only partially co-localize with cholera toxin B-subunit and have markedly reduced VAMP2 immunoreactivity. Synaptic vesicles loaded with pHrodo-BoNT/A-Hc exhibited a significantly reduced ability to fuse with the plasma membrane in mouse hippocampal nerve terminals when compared with pHrodo-dextran-containing synaptic vesicles and pHrodo-labeled anti-GFP nanobodies bound to VAMP2-pHluorin or vGlut-pHluorin. Similar results were also obtained at the amphibian neuromuscular junction. These results reveal that BoNT/A is internalized in a subpopulation of synaptic vesicles that are not destined to recycle, highlighting the existence of significant molecular and functional heterogeneity between synaptic vesicles.
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Affiliation(s)
- Callista B Harper
- The University of Queensland, Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, Brisbane, Queensland 4072, Australia
| | - Andreas Papadopulos
- The University of Queensland, Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, Brisbane, Queensland 4072, Australia
| | - Sally Martin
- The University of Queensland, Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, Brisbane, Queensland 4072, Australia
| | - Daniel R Matthews
- The University of Queensland, Queensland Brain Institute, Brisbane, Queensland 4072, Australia
| | - Garry P Morgan
- The University of Queensland, Centre for Microscopy and Microanalysis, Brisbane, Queensland 4072, Australia
| | - Tam H Nguyen
- The University of Queensland, Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, Brisbane, Queensland 4072, Australia
| | - Tong Wang
- The University of Queensland, Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, Brisbane, Queensland 4072, Australia
| | - Deepak Nair
- Interdisciplinary Institute for Neuroscience, The University of Bordeaux, Bordeaux, 33000, France.,Centre for Neuroscience, Indian Institute of Science, Bangalore, 560012, India
| | - Daniel Choquet
- Interdisciplinary Institute for Neuroscience, The University of Bordeaux, Bordeaux, 33000, France
| | - Frederic A Meunier
- The University of Queensland, Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, Brisbane, Queensland 4072, Australia
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122
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123
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Analyzing Protein Clusters on the Plasma Membrane: Application of Spatial Statistical Analysis Methods on Super-Resolution Microscopy Images. FOCUS ON BIO-IMAGE INFORMATICS 2016; 219:95-122. [DOI: 10.1007/978-3-319-28549-8_4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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124
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IFT20 controls LAT recruitment to the immune synapse and T-cell activation in vivo. Proc Natl Acad Sci U S A 2015; 113:386-91. [PMID: 26715756 DOI: 10.1073/pnas.1513601113] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Biogenesis of the immune synapse at the interface between antigen-presenting cells and T cells assembles and organizes a large number of membrane proteins required for effective signaling through the T-cell receptor. We showed previously that the intraflagellar transport protein 20 (IFT20), a component of the intraflagellar transport system, controls polarized traffic during immune synapse assembly. To investigate the role of IFT20 in primary CD4(+) T cells in vitro and in vivo, we generated mice bearing a conditional defect of IFT20 expression in T cells. We show that in the absence of IFT20, although cell spreading and the polarization of the centrosome were unaffected, T-cell receptor (TCR)-mediated signaling and recruitment of the signaling adaptor LAT (linker for activation of T cells) at the immune synapse were reduced. As a consequence, CD4(+) T-cell activation and proliferation were also defective. In vivo, conditional IFT20-deficient mice failed to mount effective antigen-specific T-cell responses, and their T cells failed to induce colitis after adoptive transfer to Rag(-/-) mice. IFT20 is therefore required for the delivery of the intracellular pool of LAT to the immune synapse in naive primary T lymphocytes and for effective T-cell responses in vivo.
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125
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Abstract
The local structure and composition of the outer membrane of an animal cell are important factors in the control of many membrane processes and mechanisms. These include signaling, sorting, and exo- and endocytic processes that are occurring all the time in a living cell. Paradoxically, not only are the local structure and composition of the membrane matters of much debate and discussion, the mechanisms that govern its genesis remain highly controversial. Here, we discuss a swathe of new technological advances that may be applied to understand the local structure and composition of the membrane of a living cell from the molecular scale to the scale of the whole membrane.
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Affiliation(s)
- Thomas S van Zanten
- National Centre for Biological Sciences (TIFR), Bellary Road, Bangalore, 560065, India
| | - Satyajit Mayor
- National Centre for Biological Sciences (TIFR), Bellary Road, Bangalore, 560065, India
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126
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Scarselli M, Annibale P, McCormick PJ, Kolachalam S, Aringhieri S, Radenovic A, Corsini GU, Maggio R. Revealing G-protein-coupled receptor oligomerization at the single-molecule level through a nanoscopic lens: methods, dynamics and biological function. FEBS J 2015; 283:1197-217. [PMID: 26509747 DOI: 10.1111/febs.13577] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 09/29/2015] [Accepted: 10/23/2015] [Indexed: 11/30/2022]
Abstract
The introduction of super-resolution fluorescence microscopy has allowed the visualization of single proteins in their biological environment. Recently, these techniques have been applied to determine the organization of class A G-protein-coupled receptors (GPCRs), and to determine whether they exist as monomers, dimers and/or higher-order oligomers. On this subject, this review highlights recent evidence from photoactivated localization microscopy (PALM), which allows the visualization of single molecules in dense samples, and single-molecule tracking (SMT), which determines how GPCRs move and interact in living cells in the presence of different ligands. PALM has demonstrated that GPCR oligomerization depends on the receptor subtype, the cell type, the actin cytoskeleton, and other proteins. Conversely, SMT has revealed the transient dynamics of dimer formation, whereby receptors show a monomer-dimer equilibrium characterized by rapid association and dissociation. At steady state, depending on the subtype, approximately 30-50% of receptors are part of dimeric complexes. Notably, the existence of many GPCR dimers/oligomers is also supported by well-known techniques, such as resonance energy transfer methodologies, and by approaches that exploit fluorescence fluctuations, such as fluorescence correlation spectroscopy (FCS). Future research using single-molecule methods will deepen our knowledge related to the function and druggability of homo-oligomers and hetero-oligomers.
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Affiliation(s)
- Marco Scarselli
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Paolo Annibale
- Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, Lausanne, Switzerland
| | | | - Shivakumar Kolachalam
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Stefano Aringhieri
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Aleksandra Radenovic
- Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, Lausanne, Switzerland
| | - Giovanni U Corsini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Roberto Maggio
- Biotechnological and Applied Clinical Sciences Department, University of L'Aquila, Italy
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127
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Griffié J, Boelen L, Burn G, Cope AP, Owen DM. Topographic prominence as a method for cluster identification in single-molecule localisation data. JOURNAL OF BIOPHOTONICS 2015; 8:925-934. [PMID: 25663080 DOI: 10.1002/jbio.201400127] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 12/03/2014] [Accepted: 12/19/2014] [Indexed: 06/04/2023]
Abstract
Single-molecule localisation based super-resolution fluorescence imaging produces maps of the coordinates of fluorescent molecules in a region of interest. Cluster analysis algorithms provide information concerning the clustering characteristics of these molecules, often through the generation of cluster heat maps based on local molecular density. The goal of this study was to generate a new cluster analysis method based on a topographic approach. In particular, a topographic map of the level of clustering across a region is generated based on Getis' variant of Ripley's K-function. By using the relative heights (topographic prominence, TP) of the peaks in the map, cluster characteristics can be identified more accurately than by using previously demonstrated height thresholds. Analogous to geological TP, the concepts of wet and dry TP and topographic isolation are introduced to generate binary maps. The algorithm is validated using simulated and experimental data and found to significantly outperform previous cluster identification methods. Illustration of the topographic prominence based cluster analysis algorithm.
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Affiliation(s)
- Juliette Griffié
- Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, Hodgkin Building, Guy's Campus, London, SE1 1UL, United Kingdom
| | - Lies Boelen
- Section of Immunology, Division of Infectious Diseases, Faculty of Medicine, Imperial College London, Praed Street, St Mary's Campus, London, United Kingdom
| | - Garth Burn
- Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, Hodgkin Building, Guy's Campus, London, SE1 1UL, United Kingdom
| | - Andrew P Cope
- Academic Department of Rheumatology, Division of Immunology, Infection and Inflammatory Disease, Faculty of Life Sciences and Medicine, King's College London, New Hunt's House, Guy's Campus, London, SE1 1UL, United Kingdom
| | - Dylan M Owen
- Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, Hodgkin Building, Guy's Campus, London, SE1 1UL, United Kingdom.
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128
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Abstract
Lipid rafts are defined as cholesterol- and sphingomyelin-enriched membrane domains in the plasma membrane of cells that are highly dynamic and cannot be resolved with conventional light microscopy. Membrane proteins that are embedded in the phospholipid matrix can be grouped into raft and non-raft proteins based on their association with detergent-resistant membranes in biochemical assays. Selective lipid-protein interactions not only produce heterogeneity in the membrane, but also cause the spatial compartmentalization of membrane reactions. It has been proposed that lipid rafts function as platforms during cell signalling transduction processes such as T-cell activation (see Chapter 13 (pages 165-175)). It has been proposed that raft association co-localizes specific signalling proteins that may yield the formation of the observed signalling microclusters at the immunological synapses. However, because of the nanometre size and high dynamics of lipid rafts, direct observations have been technically challenging, leading to an ongoing discussion of the lipid raft model and its alternatives. Recent developments in fluorescence imaging techniques have provided new opportunities to investigate the organization of cell membranes with unprecedented spatial resolution. In this chapter, we describe the concept of the lipid raft and alternative models and how new imaging technologies have advanced these concepts.
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129
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Rubin-Delanchy P, Burn GL, Griffié J, Williamson DJ, Heard NA, Cope AP, Owen DM. Bayesian cluster identification in single-molecule localization microscopy data. Nat Methods 2015; 12:1072-6. [PMID: 26436479 DOI: 10.1038/nmeth.3612] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 09/02/2015] [Indexed: 12/18/2022]
Abstract
Single-molecule localization-based super-resolution microscopy techniques such as photoactivated localization microscopy (PALM) and stochastic optical reconstruction microscopy (STORM) produce pointillist data sets of molecular coordinates. Although many algorithms exist for the identification and localization of molecules from raw image data, methods for analyzing the resulting point patterns for properties such as clustering have remained relatively under-studied. Here we present a model-based Bayesian approach to evaluate molecular cluster assignment proposals, generated in this study by analysis based on Ripley's K function. The method takes full account of the individual localization precisions calculated for each emitter. We validate the approach using simulated data, as well as experimental data on the clustering behavior of CD3ζ, a subunit of the CD3 T cell receptor complex, in resting and activated primary human T cells.
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Affiliation(s)
- Patrick Rubin-Delanchy
- School of Mathematics, Heilbronn Institute for Mathematical Research, University of Bristol, Bristol, UK
| | - Garth L Burn
- Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, London, UK
| | - Juliette Griffié
- Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, London, UK
| | - David J Williamson
- Manchester Collaborative Centre for Inflammation Research, University of Manchester, Manchester, UK
| | | | - Andrew P Cope
- Division of Immunology, Infection and Inflammatory Disease, Academic Department of Rheumatology, King's College London, London, UK
| | - Dylan M Owen
- Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, London, UK
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130
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Pham S, Tabarin T, Garvey M, Pade C, Rossy J, Monaghan P, Hyatt A, Böcking T, Leis A, Gaus K, Mak J. Cryo-electron microscopy and single molecule fluorescent microscopy detect CD4 receptor induced HIV size expansion prior to cell entry. Virology 2015; 486:121-33. [PMID: 26432024 DOI: 10.1016/j.virol.2015.09.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 09/09/2015] [Accepted: 09/10/2015] [Indexed: 10/23/2022]
Abstract
Viruses are often thought to have static structure, and they only remodel after the viruses have entered target cells. Here, we detected a size expansion of virus particles prior to viral entry using cryo-electron microscopy (cryo-EM) and single molecule fluorescence imaging. HIV expanded both under cell-free conditions with soluble receptor CD4 (sCD4) targeting the CD4 binding site on the HIV-1 envelope protein (Env) and when HIV binds to receptor on cellular membrane. We have shown that the HIV Env is needed to facilitate receptor induced virus size expansions, showing that the 'lynchpin' for size expansion is highly specific. We demonstrate that the size expansion required maturation of HIV and an internal capsid core with wild type stability, suggesting that different HIV compartments are linked and are involved in remodelling. Our work reveals a previously unknown event in HIV entry, and we propose that this pre-entry priming process enables HIV particles to facilitate the subsequent steps in infection.
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Affiliation(s)
- Son Pham
- Deakin University, Victoria 3216, Australia; CSIRO Australian Animal Health Laboratory, Victoria 3220, Australia
| | - Thibault Tabarin
- ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, New South Wales 3220, Australia
| | - Megan Garvey
- Deakin University, Victoria 3216, Australia; CSIRO Australian Animal Health Laboratory, Victoria 3220, Australia
| | - Corinna Pade
- Deakin University, Victoria 3216, Australia; CSIRO Australian Animal Health Laboratory, Victoria 3220, Australia
| | - Jérémie Rossy
- ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, New South Wales 3220, Australia
| | - Paul Monaghan
- CSIRO Australian Animal Health Laboratory, Victoria 3220, Australia
| | - Alex Hyatt
- CSIRO Australian Animal Health Laboratory, Victoria 3220, Australia
| | - Till Böcking
- ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, New South Wales 3220, Australia
| | - Andrew Leis
- CSIRO Australian Animal Health Laboratory, Victoria 3220, Australia
| | - Katharina Gaus
- ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, New South Wales 3220, Australia.
| | - Johnson Mak
- Deakin University, Victoria 3216, Australia; CSIRO Australian Animal Health Laboratory, Victoria 3220, Australia.
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131
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Schatzlmaier P, Supper V, Göschl L, Zwirzitz A, Eckerstorfer P, Ellmeier W, Huppa JB, Stockinger H. Rapid multiplex analysis of lipid raft components with single-cell resolution. Sci Signal 2015; 8:rs11. [PMID: 26396269 DOI: 10.1126/scisignal.aac5584] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Lipid rafts, a distinct class of highly dynamic cell membrane microdomains, are integral to cell homeostasis, differentiation, and signaling. However, their quantitative examination is challenging when working with rare cells, developmentally heterogeneous cell populations, or molecules that only associate weakly with lipid rafts. We present a fast biochemical method, which is based on lipid raft components associating with the nucleus upon partial lysis during centrifugation through nonionic detergent. Requiring little starting material or effort, our protocol enabled the multidimensional flow cytometric quantitation of raft-resident proteins with single-cell resolution, thereby assessing the membrane components from a few cells in complex cell populations, as well as their dynamics resulting from cell signaling, differentiation, or genetic mutation.
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Affiliation(s)
- Philipp Schatzlmaier
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Verena Supper
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Lisa Göschl
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria. Division of Rheumatology, Department of Internal Medicine III, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria
| | - Alexander Zwirzitz
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Paul Eckerstorfer
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Wilfried Ellmeier
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Johannes B Huppa
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria.
| | - Hannes Stockinger
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria.
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132
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Maity PC, Blount A, Jumaa H, Ronneberger O, Lillemeier BF, Reth M. B cell antigen receptors of the IgM and IgD classes are clustered in different protein islands that are altered during B cell activation. Sci Signal 2015; 8:ra93. [PMID: 26373673 DOI: 10.1126/scisignal.2005887] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The B cell antigen receptors (BCRs) play an important role in the clonal selection of B cells and their differentiation into antibody-secreting plasma cells. Mature B cells have both immunoglobulin M (IgM) and IgD types of BCRs, which have identical antigen-binding sites and are both associated with the signaling subunits Igα and Igβ, but differ in their membrane-bound heavy chain isoforms. By two-color direct stochastic optical reconstruction microscopy (dSTORM), we showed that IgM-BCRs and IgD-BCRs reside in the plasma membrane in different protein islands with average sizes of 150 and 240 nm, respectively. Upon B cell activation, the BCR protein islands became smaller and more dispersed such that the IgM-BCRs and IgD-BCRs were found in close proximity to each other. Moreover, specific stimulation of one class of BCR had minimal effects on the organization of the other. These conclusions were supported by the findings from two-marker transmission electron microscopy and proximity ligation assays. Together, these data provide evidence for a preformed multimeric organization of BCRs on the plasma membrane that is remodeled after B cell activation.
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Affiliation(s)
- Palash Chandra Maity
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, D-79104 Freiburg, Germany. Department of Molecular Immunology, Institute of Biology III at the Faculty of Biology of the University of Freiburg, D-79104, and at the Max Planck Institute of Immunobiology and Epigenetics, D-79108 Freiburg, Germany.
| | - Amy Blount
- Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Hassan Jumaa
- Department of Molecular Immunology, Institute of Biology III at the Faculty of Biology of the University of Freiburg, D-79104, and at the Max Planck Institute of Immunobiology and Epigenetics, D-79108 Freiburg, Germany. Institute of Immunology, Ulm University, D-89081 Ulm, Germany
| | - Olaf Ronneberger
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, D-79104 Freiburg, Germany. Institute of Computer Science, University of Freiburg, D-79110 Freiburg Germany
| | | | - Michael Reth
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, D-79104 Freiburg, Germany. Department of Molecular Immunology, Institute of Biology III at the Faculty of Biology of the University of Freiburg, D-79104, and at the Max Planck Institute of Immunobiology and Epigenetics, D-79108 Freiburg, Germany.
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133
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Levet F, Hosy E, Kechkar A, Butler C, Beghin A, Choquet D, Sibarita JB. SR-Tesseler: a method to segment and quantify localization-based super-resolution microscopy data. Nat Methods 2015; 12:1065-71. [DOI: 10.1038/nmeth.3579] [Citation(s) in RCA: 290] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 07/03/2015] [Indexed: 12/18/2022]
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134
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The Immune Adaptor SLP-76 Binds to SUMO-RANGAP1 at Nuclear Pore Complex Filaments to Regulate Nuclear Import of Transcription Factors in T Cells. Mol Cell 2015; 59:840-9. [PMID: 26321253 PMCID: PMC4576164 DOI: 10.1016/j.molcel.2015.07.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 06/01/2015] [Accepted: 07/17/2015] [Indexed: 12/03/2022]
Abstract
While immune cell adaptors regulate proximal T cell signaling, direct regulation of the nuclear pore complex (NPC) has not been reported. NPC has cytoplasmic filaments composed of RanGAP1 and RanBP2 with the potential to interact with cytoplasmic mediators. Here, we show that the immune cell adaptor SLP-76 binds directly to SUMO-RanGAP1 of cytoplasmic fibrils of the NPC, and that this interaction is needed for optimal NFATc1 and NF-κB p65 nuclear entry in T cells. Transmission electron microscopy showed anti-SLP-76 cytoplasmic labeling of the majority of NPCs in anti-CD3 activated T cells. Further, SUMO-RanGAP1 bound to the N-terminal lysine 56 of SLP-76 where the interaction was needed for optimal RanGAP1-NPC localization and GAP exchange activity. While the SLP-76-RanGAP1 (K56E) mutant had no effect on proximal signaling, it impaired NF-ATc1 and p65/RelA nuclear entry and in vivo responses to OVA peptide. Overall, we have identified SLP-76 as a direct regulator of nuclear pore function in T cells. Immune adaptor SLP-76 binds to SUMO-RanGAP1 of cytoplasmic fibrils of the NPC SLP-76 K-56 binding needed for optimal RanGAP1 localization and exchange activity SLP-76 K56E mutant impaired NF-ATc1 and NFκB p65 (RelA) nuclear entry Immune adaptors directly regulate nuclear entry of transcription factors in T cells
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135
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Garcia-Parajo MF, Cambi A, Torreno-Pina JA, Thompson N, Jacobson K. Nanoclustering as a dominant feature of plasma membrane organization. J Cell Sci 2015; 127:4995-5005. [PMID: 25453114 DOI: 10.1242/jcs.146340] [Citation(s) in RCA: 196] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Early studies have revealed that some mammalian plasma membrane proteins exist in small nanoclusters. The advent of super-resolution microscopy has corroborated and extended this picture, and led to the suggestion that many, if not most, membrane proteins are clustered at the plasma membrane at nanoscale lengths. In this Commentary, we present selected examples of glycosylphosphatidyl-anchored proteins, Ras family members and several immune receptors that provide evidence for nanoclustering. We advocate the view that nanoclustering is an important part of the hierarchical organization of proteins in the plasma membrane. According to this emerging picture, nanoclusters can be organized on the mesoscale to form microdomains that are capable of supporting cell adhesion, pathogen binding and immune cell-cell recognition amongst other functions. Yet, a number of outstanding issues concerning nanoclusters remain open, including the details of their molecular composition, biogenesis, size, stability, function and regulation. Notions about these details are put forth and suggestions are made about nanocluster function and why this general feature of protein nanoclustering appears to be so prevalent.
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Affiliation(s)
- Maria F Garcia-Parajo
- ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
| | - Alessandra Cambi
- Nanobiophysics, MIRA Institute for Biomedical Technology and Technical Medicine and MESA+ Institute for Nanotechnology, University of Twente, 7522 NB Enschede, The Netherlands Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6500 HB Nijmegen, The Netherlands
| | - Juan A Torreno-Pina
- ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain
| | - Nancy Thompson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, USA
| | - Ken Jacobson
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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136
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Wieneke R, Raulf A, Kollmannsperger A, Heilemann M, Tampé R. SLAP: Small Labeling Pair for Single-Molecule Super-Resolution Imaging. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/anie.201503215] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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137
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Wieneke R, Raulf A, Kollmannsperger A, Heilemann M, Tampé R. SLAP: Small Labeling Pair for Single-Molecule Super-Resolution Imaging. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201503215] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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138
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Burgert A, Letschert S, Doose S, Sauer M. Artifacts in single-molecule localization microscopy. Histochem Cell Biol 2015; 144:123-31. [PMID: 26138928 DOI: 10.1007/s00418-015-1340-4] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2015] [Indexed: 01/11/2023]
Abstract
Single-molecule localization microscopy provides subdiffraction resolution images with virtually molecular resolution. Through the availability of commercial instruments and open-source reconstruction software, achieving super resolution is now public domain. However, despite its conceptual simplicity, localization microscopy remains prone to user errors. Using direct stochastic optical reconstruction microscopy, we investigate the impact of irradiation intensity, label density and photoswitching behavior on the distribution of membrane proteins in reconstructed super-resolution images. We demonstrate that high emitter densities in combination with inappropriate photoswitching rates give rise to the appearance of artificial membrane clusters. Especially, two-dimensional imaging of intrinsically three-dimensional membrane structures like microvilli, filopodia, overlapping membranes and vesicles with high local emitter densities is prone to generate artifacts. To judge the quality and reliability of super-resolution images, the single-molecule movies recorded to reconstruct the images have to be carefully investigated especially when investigating membrane organization and cluster analysis.
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Affiliation(s)
- Anne Burgert
- Department of Biotechnology and Biophysics, University Würzburg, Am Hubland, 97074, Würzburg, Germany
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139
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Tang Y, Dai L, Zhang X, Li J, Hendriks J, Fan X, Gruteser N, Meisenberg A, Baumann A, Katranidis A, Gensch T. SNSMIL, a real-time single molecule identification and localization algorithm for super-resolution fluorescence microscopy. Sci Rep 2015; 5:11073. [PMID: 26098742 PMCID: PMC4476421 DOI: 10.1038/srep11073] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 05/08/2015] [Indexed: 11/09/2022] Open
Abstract
Single molecule localization based super-resolution fluorescence microscopy offers significantly higher spatial resolution than predicted by Abbe's resolution limit for far field optical microscopy. Such super-resolution images are reconstructed from wide-field or total internal reflection single molecule fluorescence recordings. Discrimination between emission of single fluorescent molecules and background noise fluctuations remains a great challenge in current data analysis. Here we present a real-time, and robust single molecule identification and localization algorithm, SNSMIL (Shot Noise based Single Molecule Identification and Localization). This algorithm is based on the intrinsic nature of noise, i.e., its Poisson or shot noise characteristics and a new identification criterion, QSNSMIL, is defined. SNSMIL improves the identification accuracy of single fluorescent molecules in experimental or simulated datasets with high and inhomogeneous background. The implementation of SNSMIL relies on a graphics processing unit (GPU), making real-time analysis feasible as shown for real experimental and simulated datasets.
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Affiliation(s)
- Yunqing Tang
- National Center for Nanoscience and Technology of China No.11, Beiyitiao Zhongguancun 100190 Beijing, P.R. China
- Department of Physics, Chongqing University, Chongqing 400044, P.R. China
- State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, 100190 Beijing, P.R. China
| | - Luru Dai
- National Center for Nanoscience and Technology of China No.11, Beiyitiao Zhongguancun 100190 Beijing, P.R. China
| | - Xiaoming Zhang
- National Center for Nanoscience and Technology of China No.11, Beiyitiao Zhongguancun 100190 Beijing, P.R. China
| | - Junbai Li
- National Center for Nanoscience and Technology of China No.11, Beiyitiao Zhongguancun 100190 Beijing, P.R. China
- Institute of Chemistry, Chinese Academy of Sciences, 100190 Beijing, P.R. China
| | - Johnny Hendriks
- Institute of Complex Systems (ICS-4, Cellular Biophysics), Forschungszentrum Jülich, Leo-Brandt-Str., 52428 Jülich, Germany
| | - Xiaoming Fan
- Institute of Complex Systems (ICS-4, Cellular Biophysics), Forschungszentrum Jülich, Leo-Brandt-Str., 52428 Jülich, Germany
| | - Nadine Gruteser
- Institute of Complex Systems (ICS-4, Cellular Biophysics), Forschungszentrum Jülich, Leo-Brandt-Str., 52428 Jülich, Germany
| | - Annika Meisenberg
- Institute of Complex Systems (ICS-4, Cellular Biophysics), Forschungszentrum Jülich, Leo-Brandt-Str., 52428 Jülich, Germany
| | - Arnd Baumann
- Institute of Complex Systems (ICS-4, Cellular Biophysics), Forschungszentrum Jülich, Leo-Brandt-Str., 52428 Jülich, Germany
| | - Alexandros Katranidis
- Institute of Complex Systems (ICS-5, Molecular Biophysics), Forschungszentrum Jülich, Leo-Brandt-Str., 52428 Jülich, Germany
| | - Thomas Gensch
- Institute of Complex Systems (ICS-4, Cellular Biophysics), Forschungszentrum Jülich, Leo-Brandt-Str., 52428 Jülich, Germany
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140
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Healey EG, Bishop B, Elegheert J, Bell CH, Padilla-Parra S, Siebold C. Repulsive guidance molecule is a structural bridge between neogenin and bone morphogenetic protein. Nat Struct Mol Biol 2015; 22:458-65. [PMID: 25938661 PMCID: PMC4456160 DOI: 10.1038/nsmb.3016] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 03/31/2015] [Indexed: 02/07/2023]
Abstract
Repulsive guidance molecules (RGMs) control crucial processes including cell motility, adhesion, immune-cell regulation and systemic iron metabolism. RGMs signal via the neogenin (NEO1) and the bone morphogenetic protein (BMP) pathways. Here, we report crystal structures of the N-terminal domains of all human RGM family members in complex with the BMP ligand BMP2, revealing a new protein fold and a conserved BMP-binding mode. Our structural and functional data suggest a pH-linked mechanism for RGM-activated BMP signaling and offer a rationale for RGM mutations causing juvenile hemochromatosis. We also determined the crystal structure of the ternary BMP2-RGM-NEO1 complex, which, along with solution scattering and live-cell super-resolution fluorescence microscopy, indicates BMP-induced clustering of the RGM-NEO1 complex. Our results show how RGM acts as the central hub that links BMP and NEO1 and physically connects these fundamental signaling pathways.
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Affiliation(s)
- Eleanor G Healey
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Benjamin Bishop
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Jonathan Elegheert
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Christian H Bell
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Sergi Padilla-Parra
- 1] Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK. [2] Cellular Imaging Core, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Christian Siebold
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
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141
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Burkhardt JK. Seeing is believing: sorting out signaling events at the immunological synapse. THE JOURNAL OF IMMUNOLOGY 2015; 194:4059-60. [PMID: 25888700 DOI: 10.4049/jimmunol.1500584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Janis K Burkhardt
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
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142
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Curthoys NM, Parent M, Mlodzianoski M, Nelson AJ, Lilieholm J, Butler MB, Valles M, Hess ST. Dances with Membranes: Breakthroughs from Super-resolution Imaging. CURRENT TOPICS IN MEMBRANES 2015; 75:59-123. [PMID: 26015281 PMCID: PMC5584789 DOI: 10.1016/bs.ctm.2015.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Biological membrane organization mediates numerous cellular functions and has also been connected with an immense number of human diseases. However, until recently, experimental methodologies have been unable to directly visualize the nanoscale details of biological membranes, particularly in intact living cells. Numerous models explaining membrane organization have been proposed, but testing those models has required indirect methods; the desire to directly image proteins and lipids in living cell membranes is a strong motivation for the advancement of technology. The development of super-resolution microscopy has provided powerful tools for quantification of membrane organization at the level of individual proteins and lipids, and many of these tools are compatible with living cells. Previously inaccessible questions are now being addressed, and the field of membrane biology is developing rapidly. This chapter discusses how the development of super-resolution microscopy has led to fundamental advances in the field of biological membrane organization. We summarize the history and some models explaining how proteins are organized in cell membranes, and give an overview of various super-resolution techniques and methods of quantifying super-resolution data. We discuss the application of super-resolution techniques to membrane biology in general, and also with specific reference to the fields of actin and actin-binding proteins, virus infection, mitochondria, immune cell biology, and phosphoinositide signaling. Finally, we present our hopes and expectations for the future of super-resolution microscopy in the field of membrane biology.
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Affiliation(s)
- Nikki M. Curthoys
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Matthew Parent
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | | | - Andrew J. Nelson
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Jennifer Lilieholm
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Michael B. Butler
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Matthew Valles
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Samuel T. Hess
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
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143
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The nanoscale organization of signaling domains at the plasma membrane. CURRENT TOPICS IN MEMBRANES 2015; 75:125-65. [PMID: 26015282 DOI: 10.1016/bs.ctm.2015.03.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In this chapter, we present an overview of the role of the nanoscale organization of signaling domains in regulating key cellular processes. In particular, we illustrate the importance of protein and lipid nanodomains as triggers and mediators of cell signaling. As particular examples, we summarize the state of the art of understanding the role of nanodomains in the mounting of an immune response, cellular adhesion, intercellular communication, and cell proliferation. Thus, this chapter underlines the essential role the nanoscale organization of key signaling proteins and lipid domains. We will also see how nanodomains play an important role in the lifecycle of many pathogens relevant to human disease and therefore illustrate how these structures may become future therapeutic targets.
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144
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Accounting for limited detection efficiency and localization precision in cluster analysis in single molecule localization microscopy. PLoS One 2015; 10:e0118767. [PMID: 25794150 PMCID: PMC4368834 DOI: 10.1371/journal.pone.0118767] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Accepted: 01/14/2015] [Indexed: 11/20/2022] Open
Abstract
Single Molecule Localization Microscopy techniques like PhotoActivated Localization Microscopy, with their sub-diffraction limit spatial resolution, have been popularly used to characterize the spatial organization of membrane proteins, by means of quantitative cluster analysis. However, such quantitative studies remain challenged by the techniques’ inherent sources of errors such as a limited detection efficiency of less than 60%, due to incomplete photo-conversion, and a limited localization precision in the range of 10 – 30nm, varying across the detected molecules, mainly depending on the number of photons collected from each. We provide analytical methods to estimate the effect of these errors in cluster analysis and to correct for them. These methods, based on the Ripley’s L(r) – r or Pair Correlation Function popularly used by the community, can facilitate potentially breakthrough results in quantitative biology by providing a more accurate and precise quantification of protein spatial organization.
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145
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The coreceptor CD4 is expressed in distinct nanoclusters and does not colocalize with T-cell receptor and active protein tyrosine kinase p56lck. Proc Natl Acad Sci U S A 2015; 112:E1604-13. [PMID: 25829544 DOI: 10.1073/pnas.1503532112] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
CD4 molecules on the surface of T lymphocytes greatly augment the sensitivity and activation process of these cells, but how it functions is not fully understood. Here we studied the spatial organization of CD4, and its relationship to T-cell antigen receptor (TCR) and the active form of Src kinase p56lck (Lck) using single and dual-color photoactivated localization microscopy (PALM) and direct stochastic optical reconstruction microscopy (dSTORM). In nonactivated T cells, CD4 molecules are clustered in small protein islands, as are TCR and Lck. By dual-color imaging, we find that CD4, TCR, and Lck are localized in their separate clusters with limited interactions in the interfaces between them. Upon T-cell activation, the TCR and CD4 begin clustering together, developing into microclusters, and undergo a larger scale redistribution to form supramolecluar activation clusters (SMACs). CD4 and Lck localize in the inner TCR region of the SMAC, but this redistribution of disparate cluster structures results in enhanced segregation from each other. In nonactivated cells these preclustered structures and the limited interactions between them may serve to limit spontaneous and random activation events. However, the small sizes of these island structures also ensure large interfacial surfaces for potential interactions and signal amplification when activation is initiated. In the later activation stages, the increasingly larger clusters and their segregation from each other reduce the interfacial surfaces and could have a dampening effect. These highly differentiated spatial distributions of TCR, CD4, and Lck and their changes during activation suggest that there is a more complex hierarchy than previously thought.
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146
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Pandžić E, Rossy J, Gaus K. Tracking molecular dynamics without tracking: image correlation of photo-activation microscopy. Methods Appl Fluoresc 2015; 3:014006. [PMID: 29148482 DOI: 10.1088/2050-6120/3/1/014006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Measuring protein dynamics in the plasma membrane can provide insights into the mechanisms of receptor signaling and other cellular functions. To quantify protein dynamics on the single molecule level over the entire cell surface, sophisticated approaches such as single particle tracking (SPT), photo-activation localization microscopy (PALM) and fluctuation-based analysis have been developed. However, analyzing molecular dynamics of fluorescent particles with intermittent excitation and low signal-to-noise ratio present at high densities has remained a challenge. We overcame this problem by applying spatio-temporal image correlation spectroscopy (STICS) analysis to photo-activated (PA) microscopy time series. In order to determine under which imaging conditions this approach is valid, we simulated PA images of diffusing particles in a homogeneous environment and varied photo-activation, reversible blinking and irreversible photo-bleaching rates. Further, we simulated data with high particle densities that populated mobile objects (such as adhesions and vesicles) that often interfere with STICS and fluctuation-based analysis. We demonstrated in experimental measurements that the diffusion coefficient of the epidermal growth factor receptor (EGFR) fused to PAGFP in live COS-7 cells can be determined in the plasma membrane and revealed differences in the time-dependent diffusion maps between wild-type and mutant Lck in activated T cells. In summary, we have developed a new analysis approach for live cell photo-activation microscopy data based on image correlation spectroscopy to quantify the spatio-temporal dynamics of single proteins.
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Affiliation(s)
- Elvis Pandžić
- ARC Centre for Advanced Molecular Imaging, Australian Centre for NanoMedicine University of New South Wales Australia, Sydney, NSW, Australia
| | - Jérémie Rossy
- ARC Centre for Advanced Molecular Imaging, Australian Centre for NanoMedicine University of New South Wales Australia, Sydney, NSW, Australia
| | - Katharina Gaus
- ARC Centre for Advanced Molecular Imaging, Australian Centre for NanoMedicine University of New South Wales Australia, Sydney, NSW, Australia
- Lowy Cancer Research Centre, Centre for Vascular Research Level 3, Kensington, NSW, Australia
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147
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Diffraction-unlimited imaging: from pretty pictures to hard numbers. Cell Tissue Res 2015; 360:151-78. [DOI: 10.1007/s00441-014-2109-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 12/22/2014] [Indexed: 10/23/2022]
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148
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Alvarez-Guaita A, Vilà de Muga S, Owen DM, Williamson D, Magenau A, García-Melero A, Reverter M, Hoque M, Cairns R, Cornely R, Tebar F, Grewal T, Gaus K, Ayala-Sanmartín J, Enrich C, Rentero C. Evidence for annexin A6-dependent plasma membrane remodelling of lipid domains. Br J Pharmacol 2015; 172:1677-90. [PMID: 25409976 DOI: 10.1111/bph.13022] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 11/11/2014] [Accepted: 11/14/2014] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND AND PURPOSE Annexin A6 (AnxA6) is a calcium-dependent phospholipid-binding protein that can be recruited to the plasma membrane to function as a scaffolding protein to regulate signal complex formation, endo- and exocytic pathways as well as distribution of cellular cholesterol. Here, we have investigated how AnxA6 influences the membrane order. EXPERIMENTAL APPROACH We used Laurdan and di-4-ANEPPDHQ staining in (i) artificial membranes; (ii) live cells to investigate membrane packing and ordered lipid phases; and (iii) a super-resolution imaging (photoactivated localization microscopy, PALM) and Ripley's K second-order point pattern analysis approach to assess how AnxA6 regulates plasma membrane order domains and protein clustering. KEY RESULTS In artificial membranes, purified AnxA6 induced a global increase in membrane order. However, confocal microscopy using di-4-ANEPPDHQ in live cells showed that cells expressing AnxA6, which reduces plasma membrane cholesterol levels and modifies the actin cytoskeleton meshwork, displayed a decrease in membrane order (∼15 and 30% in A431 and MEF cells respectively). PALM data from Lck10 and Src15 membrane raft/non-raft markers revealed that AnxA6 expression induced clustering of both raft and non-raft markers. Altered clustering of Lck10 and Src15 in cells expressing AnxA6 was also observed after cholesterol extraction with methyl-β-cyclodextrin or actin cytoskeleton disruption with latrunculin B. CONCLUSIONS AND IMPLICATIONS AnxA6-induced plasma membrane remodelling indicated that elevated AnxA6 expression decreased membrane order through the regulation of cellular cholesterol homeostasis and the actin cytoskeleton. This study provides the first evidence from live cells that support current models of annexins as membrane organizers.
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Affiliation(s)
- Anna Alvarez-Guaita
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain
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149
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Magenau A, Owen DM, Yamamoto Y, Tran J, Kwiatek JM, Parton RG, Gaus K. Discreet and distinct clustering of five model membrane proteins revealed by single molecule localization microscopy. Mol Membr Biol 2015; 32:11-8. [PMID: 25586872 DOI: 10.3109/09687688.2014.990997] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Compartmentalization is a functionally important property of the plasma membrane, yet the underlying principles that organize membrane proteins into distinct domains are not well understood. Using single molecule localization microscopy, we assessed the clustering of five model membrane proteins in the plasma membrane of HeLa cells. All five proteins formed discrete and distinct nano-scaled clusters. The extent of clustering of the five proteins, independent of their membrane anchors, increased significantly when the fluorescent protein mEOS2 was employed, suggesting that protein-protein interactions are a key driver for clustering. Further, actin depolymerization or reduction of membrane order had a greater, and in some instances opposing effects on the clustering of membrane proteins fused to mEOS2 compared to PS-CFP2-fusion proteins. The data propose that protein interactions can override the lateral organization imposed by membrane anchors to provide an exquisite regulation of the mosaic-like compartmentalization of the plasma membrane.
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Affiliation(s)
- Astrid Magenau
- Centre for Vascular Research and Australian Centre for NanoMedicine, University of New South Wales , Sydney, Australia
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150
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3D super-resolution imaging by localization microscopy. Methods Mol Biol 2015; 1232:123-36. [PMID: 25331133 DOI: 10.1007/978-1-4939-1752-5_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Fluorescence microscopy is an important tool in all fields of biology to visualize structures and monitor dynamic processes and distributions. Contrary to conventional microscopy techniques such as confocal microscopy, which are limited by their spatial resolution, super-resolution techniques such as photoactivated localization microscopy (PALM) and stochastic optical reconstruction microscopy (STORM) have made it possible to observe and quantify structure and processes on the single molecule level. Here, we describe a method to image and quantify the molecular distribution of membrane-associated proteins in two and three dimensions with nanometer resolution.
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