1
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Platzer R, Hellmeier J, Göhring J, Perez ID, Schatzlmaier P, Bodner C, Focke‐Tejkl M, Schütz GJ, Sevcsik E, Stockinger H, Brameshuber M, Huppa JB. Monomeric agonist peptide/MHCII complexes activate T-cells in an autonomous fashion. EMBO Rep 2023; 24:e57842. [PMID: 37768718 PMCID: PMC10626418 DOI: 10.15252/embr.202357842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 09/04/2023] [Accepted: 09/14/2023] [Indexed: 09/29/2023] Open
Abstract
Molecular crowding of agonist peptide/MHC class II complexes (pMHCIIs) with structurally similar, yet per se non-stimulatory endogenous pMHCIIs is postulated to sensitize T-cells for the recognition of single antigens on the surface of dendritic cells and B-cells. When testing this premise with the use of advanced live cell microscopy, we observe pMHCIIs as monomeric, randomly distributed entities diffusing rapidly after entering the APC surface. Synaptic TCR engagement of highly abundant endogenous pMHCIIs is low or non-existent and affects neither TCR engagement of rare agonist pMHCII in early and advanced synapses nor agonist-induced TCR-proximal signaling. Our findings highlight the capacity of single freely diffusing agonist pMHCIIs to elicit the full T-cell response in an autonomous and peptide-specific fashion with consequences for adaptive immunity and immunotherapeutic approaches.
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Affiliation(s)
- René Platzer
- Center for Pathophysiology, Infectiology, Immunology, Institute for Hygiene and Applied ImmunologyMedical University of ViennaViennaAustria
| | - Joschka Hellmeier
- TU Wien, Institute of Applied PhysicsViennaAustria
- Present address:
Max Planck Institute of Biochemistry, Molecular Imaging and BionanotechnologyMartinsriedGermany
| | - Janett Göhring
- Center for Pathophysiology, Infectiology, Immunology, Institute for Hygiene and Applied ImmunologyMedical University of ViennaViennaAustria
| | - Iago Doel Perez
- Center for Pathophysiology, Infectiology, Immunology, Institute for Hygiene and Applied ImmunologyMedical University of ViennaViennaAustria
- Present address:
Takeda Manufacturing Austria AGViennaAustria
| | - Philipp Schatzlmaier
- Center for Pathophysiology, Infectiology, Immunology, Institute for Hygiene and Applied ImmunologyMedical University of ViennaViennaAustria
| | - Clara Bodner
- TU Wien, Institute of Applied PhysicsViennaAustria
| | - Margarete Focke‐Tejkl
- Center for Pathophysiology, Infectiology, Immunology, Institute for Pathophysiology and Allergy ResearchMedical University of ViennaViennaAustria
| | | | - Eva Sevcsik
- TU Wien, Institute of Applied PhysicsViennaAustria
| | - Hannes Stockinger
- Center for Pathophysiology, Infectiology, Immunology, Institute for Hygiene and Applied ImmunologyMedical University of ViennaViennaAustria
| | | | - Johannes B Huppa
- Center for Pathophysiology, Infectiology, Immunology, Institute for Hygiene and Applied ImmunologyMedical University of ViennaViennaAustria
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2
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Bodner C, Kiesenhofer D, Schütz GJ, Brameshuber M. Monte Carlo simulations for the evaluation of oligomerization data in TOCCSL experiments. Biophys J 2023:S0006-3495(23)00272-2. [PMID: 37088991 DOI: 10.1016/j.bpj.2023.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 12/14/2022] [Accepted: 04/19/2023] [Indexed: 04/25/2023] Open
Abstract
The interplay and communication between cells build the foundation of life. Many signaling processes at the cell surface and inside the cell, as well as the cellular function itself depend on protein-protein interactions and the oligomerization of proteins. In the past, we presented an approach to single out interactions of fluorescently labeled membrane proteins by combining photobleaching and single-molecule microscopy. With this approach, termed ''Thinning Out Clusters while Conserving the Stoichiometry of Labeling'' (TOCCSL, Moertelmaier et al, Appl Phys Lett, 2005), oligomerization can be detected even at physiologically high surface densities of fluorescently labeled proteins. In TOCCSL, an aperture-restricted region of the plasma membrane is irreversibly photobleached by applying a high-intensity laser pulse. During a recovery time, in which illumination is turned off, non-photobleached molecules from the non-illuminated area of the plasma membrane re-populate the aperture-restricted region. At the onset of this recovery process, these molecules can be detected as well-separated, diffraction-limited signals and their oligomerization state can be quantified. Here, we used extensive Monte Carlo simulations to provide a theoretical framework for quantitative interpretation of TOCCSL measurements. We determined the influence of experimental parameters and intrinsic characteristics of the investigated system on the outcome of a TOCCSL experiment. We identified the diffraction-affected laser intensity profile and the diffusion of molecules at the aperture edges during photobleaching as major sources of generating partially photobleached oligomers. They are falsely detected as lower order oligomers and, hence, higher order oligomers might be prevented from detection. The amount of partially photobleached oligomers that are analyzed depends on the photobleaching and the recovery time, on the mobility of molecules and - for mixed populations of oligomers - on mobility differences between different kinds of oligomers. Moreover, we quantified random colocalizations of molecules after recovery, which are falsely detected as higher-order oligomers.
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Affiliation(s)
- Clara Bodner
- Biophysics Group, Institute of Applied Physics, TU Wien, Vienna, 1040, Austria
| | - Dominik Kiesenhofer
- Biophysics Group, Institute of Applied Physics, TU Wien, Vienna, 1040, Austria
| | | | - Mario Brameshuber
- Biophysics Group, Institute of Applied Physics, TU Wien, Vienna, 1040, Austria.
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3
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Luethi D, Maier J, Rudin D, Szöllősi D, Angenoorth TJF, Stankovic S, Schittmayer M, Burger I, Yang JW, Jaentsch K, Holy M, Das AK, Brameshuber M, Camacho-Hernandez GA, Casiraghi A, Newman AH, Kudlacek O, Birner-Gruenberger R, Stockner T, Schütz GJ, Sitte HH. Phosphatidylinositol 4,5-bisphosphate (PIP 2) facilitates norepinephrine transporter dimerization and modulates substrate efflux. Commun Biol 2022; 5:1259. [PMID: 36396757 PMCID: PMC9672106 DOI: 10.1038/s42003-022-04210-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 11/01/2022] [Indexed: 11/19/2022] Open
Abstract
The plasmalemmal norepinephrine transporter (NET) regulates cardiovascular sympathetic activity by clearing extracellular norepinephrine in the synaptic cleft. Here, we investigate the subunit stoichiometry and function of NET using single-molecule fluorescence microscopy and flux assays. In particular, we show the effect of phosphatidylinositol 4,5-bisphosphate (PIP2) on NET oligomerization and efflux. NET forms monomers (~60%) and dimers (~40%) at the plasma membrane. PIP2 depletion results in a decrease in the average oligomeric state and decreases NET-mediated substrate efflux while not affecting substrate uptake. Mutation of the putative PIP2 binding residues R121, K334, and R440 to alanines does not affect NET dimerization but results in decreased substrate efflux that is not altered upon PIP2 depletion; this indicates that PIP2 interactions with these residues affect NET-mediated efflux. A dysregulation of norepinephrine and PIP2 signaling have both been implicated in neuropsychiatric and cardiovascular diseases. This study provides evidence that PIP2 directly regulates NET organization and function.
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Affiliation(s)
- Dino Luethi
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
- Institute of Applied Physics, TU Wien, Lehargasse 6, 1060, Vienna, Austria
| | - Julian Maier
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Deborah Rudin
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Dániel Szöllősi
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Thomas J F Angenoorth
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Stevan Stankovic
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Matthias Schittmayer
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria
| | - Isabella Burger
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria
| | - Jae-Won Yang
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Kathrin Jaentsch
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Marion Holy
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Anand Kant Das
- Institute of Applied Physics, TU Wien, Lehargasse 6, 1060, Vienna, Austria
- Physics Program, New York University Abu Dhabi, Saadiyat Island, 129188, Abu Dhabi, United Arab Emirates
| | - Mario Brameshuber
- Institute of Applied Physics, TU Wien, Lehargasse 6, 1060, Vienna, Austria
| | - Gisela Andrea Camacho-Hernandez
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, Baltimore, MD, 21224, USA
| | - Andrea Casiraghi
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, Baltimore, MD, 21224, USA
- Department of Pharmaceutical Sciences, University of Milan, Via Luigi Mangiagalli 25, 20133, Milan, Italy
| | - Amy Hauck Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, Baltimore, MD, 21224, USA
| | - Oliver Kudlacek
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Ruth Birner-Gruenberger
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010, Graz, Austria
| | - Thomas Stockner
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Gerhard J Schütz
- Institute of Applied Physics, TU Wien, Lehargasse 6, 1060, Vienna, Austria.
| | - Harald H Sitte
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria.
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4
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Velas L, Brameshuber M, Huppa JB, Kurz E, Dustin ML, Zelger P, Jesacher A, Schütz GJ. Three-Dimensional Single Molecule Localization Microscopy Reveals the Topography of the Immunological Synapse at Isotropic Precision below 15 nm. Nano Lett 2021; 21:9247-9255. [PMID: 34709845 PMCID: PMC8587899 DOI: 10.1021/acs.nanolett.1c03160] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
T-cells engage with antigen-presenting cells in search for antigenic peptides and form transient interfaces termed immunological synapses. Synapse topography affects receptor binding rates and the mutual segregation of proteins due to size exclusion effects. It is hence important to determine the 3D topography of the immunological synapse at high precision. Current methods provide only rather coarse images of the protein distribution within the synapse. Here, we applied supercritical angle fluorescence microscopy combined with defocused imaging, which allows three-dimensional single molecule localization microscopy (3D-SMLM) at an isotropic localization precision below 15 nm. Experiments were performed on hybrid synapses between primary T-cells and functionalized glass-supported lipid bilayers. We used 3D-SMLM to quantify the cleft size within the synapse by mapping the position of the T-cell receptor (TCR) with respect to the supported lipid bilayer, yielding average distances of 18 nm up to 31 nm for activating and nonactivating bilayers, respectively.
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Affiliation(s)
- Lukas Velas
- Institute
of Applied Physics, TU Wien, 1040 Vienna, Austria
| | | | - Johannes B. Huppa
- Institute
for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology
and Immunology, Medical University of Vienna, 1090 Vienna, Austria
| | - Elke Kurz
- Kennedy
Institute of Rheumatology, University of
Oxford, OX3 7FY Oxford, United Kingdom
| | - Michael L. Dustin
- Kennedy
Institute of Rheumatology, University of
Oxford, OX3 7FY Oxford, United Kingdom
| | - Philipp Zelger
- Division
for Biomedical Physics, Medical University
of Innsbruck, 6020 Innsbruck, Austria
| | - Alexander Jesacher
- Division
for Biomedical Physics, Medical University
of Innsbruck, 6020 Innsbruck, Austria
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5
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Schromm AB, Paulowski L, Kaconis Y, Kopp F, Koistinen M, Donoghue A, Keese S, Nehls C, Wernecke J, Garidel P, Sevcsik E, Lohner K, Sanchez-Gomez S, Martinez-de-Tejada G, Brandenburg K, Brameshuber M, Schütz GJ, Andrä J, Gutsmann T. Cathelicidin and PMB neutralize endotoxins by multifactorial mechanisms including LPS interaction and targeting of host cell membranes. Proc Natl Acad Sci U S A 2021; 118:e2101721118. [PMID: 34183393 PMCID: PMC8271772 DOI: 10.1073/pnas.2101721118] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Antimicrobial peptides (AMPs) contribute to an effective protection against infections. The antibacterial function of AMPs depends on their interactions with microbial membranes and lipids, such as lipopolysaccharide (LPS; endotoxin). Hyperinflammation induced by endotoxin is a key factor in bacterial sepsis and many other human diseases. Here, we provide a comprehensive profile of peptide-mediated LPS neutralization by systematic analysis of the effects of a set of AMPs and the peptide antibiotic polymyxin B (PMB) on the physicochemistry of endotoxin, macrophage activation, and lethality in mice. Mechanistic studies revealed that the host defense peptide LL-32 and PMB each reduce LPS-mediated activation also via a direct interaction of the peptides with the host cell. As a biophysical basis, we demonstrate modifications of the structure of cholesterol-rich membrane domains and the association of glycosylphosphatidylinositol (GPI)-anchored proteins. Our discovery of a host cell-directed mechanism of immune control contributes an important aspect in the development and therapeutic use of AMPs.
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Affiliation(s)
- Andra B Schromm
- Division of Immunobiophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany;
| | - Laura Paulowski
- Division of Immunobiophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany
- Division of Biophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany
| | - Yani Kaconis
- Division of Biophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany
| | - Franziska Kopp
- Division of Immunobiophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany
- Division of Biophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany
| | - Max Koistinen
- Division of Biophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany
| | - Annemarie Donoghue
- Division of Biophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany
| | - Susanne Keese
- Division of Immunobiophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany
| | - Christian Nehls
- Division of Biophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany
| | - Julia Wernecke
- Division of Biophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany
- Deutsches Elektronen-Synchrotron, D-22607 Hamburg, Germany
| | - Patrick Garidel
- Biophysikalische Chemie, Martin-Luther-Universität Halle-Wittenberg, D-06108 Halle, Germany
| | - Eva Sevcsik
- Institute of Applied Physics at TU Wien, Vienna 1040, Austria
| | - Karl Lohner
- Institute of Molecular Biosciences, Biophysics Division, University of Graz, A-8010 Graz, Austria
- BioTechMed-Graz, A-8010 Graz, Austria
| | - Susana Sanchez-Gomez
- Department of Microbiology and Parasitology, University of Navarra, E-31008 Pamplona, Spain
| | - Guillermo Martinez-de-Tejada
- Department of Microbiology and Parasitology, University of Navarra, E-31008 Pamplona, Spain
- Navarra Institute for Health Research, E-31008 Pamplona, Spain
| | - Klaus Brandenburg
- Division of Biophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany
| | | | | | - Jörg Andrä
- Division of Biophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany
- Department of Biotechnology, Faculty of Life Sciences, Hamburg University of Applied Sciences, D-21033 Hamburg, Germany
| | - Thomas Gutsmann
- Division of Biophysics, Research Center Borstel, Leibniz Lung Center, D-23845 Borstel, Germany
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6
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Hellmeier J, Platzer R, Eklund AS, Schlichthaerle T, Karner A, Motsch V, Schneider MC, Kurz E, Bamieh V, Brameshuber M, Preiner J, Jungmann R, Stockinger H, Schütz GJ, Huppa JB, Sevcsik E. DNA origami demonstrate the unique stimulatory power of single pMHCs as T cell antigens. Proc Natl Acad Sci U S A 2021; 118:e2016857118. [PMID: 33468643 PMCID: PMC7848602 DOI: 10.1073/pnas.2016857118] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
T cells detect with their T cell antigen receptors (TCRs) the presence of rare agonist peptide/MHC complexes (pMHCs) on the surface of antigen-presenting cells (APCs). How extracellular ligand binding triggers intracellular signaling is poorly understood, yet spatial antigen arrangement on the APC surface has been suggested to be a critical factor. To examine this, we engineered a biomimetic interface based on laterally mobile functionalized DNA origami platforms, which allow for nanoscale control over ligand distances without interfering with the cell-intrinsic dynamics of receptor clustering. When targeting TCRs via stably binding monovalent antibody fragments, we found the minimum signaling unit promoting efficient T cell activation to consist of two antibody-ligated TCRs within a distance of 20 nm. In contrast, transiently engaging antigenic pMHCs stimulated T cells robustly as well-isolated entities. These results identify pairs of antibody-bound TCRs as minimal receptor entities for effective TCR triggering yet validate the exceptional stimulatory potency of single isolated pMHC molecules.
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Affiliation(s)
| | - Rene Platzer
- Center for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, 1090 Vienna, Austria
| | - Alexandra S Eklund
- Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
- Faculty of Physics and Center for Nanoscience, Ludwig Maximilian University, 80539 Munich, Germany
| | - Thomas Schlichthaerle
- Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
- Faculty of Physics and Center for Nanoscience, Ludwig Maximilian University, 80539 Munich, Germany
| | - Andreas Karner
- University of Applied Sciences Upper Austria, 4020 Linz, Austria
| | | | | | - Elke Kurz
- Kennedy Institute of Rheumatology, University of Oxford, Oxford OX3 7FY, United Kingdom
| | - Victor Bamieh
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | | | - Johannes Preiner
- University of Applied Sciences Upper Austria, 4020 Linz, Austria
| | - Ralf Jungmann
- Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
- Faculty of Physics and Center for Nanoscience, Ludwig Maximilian University, 80539 Munich, Germany
| | - Hannes Stockinger
- Center for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, 1090 Vienna, Austria
| | | | - Johannes B Huppa
- Center for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, 1090 Vienna, Austria
| | - Eva Sevcsik
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria;
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7
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Platzer R, Rossboth BK, Schneider MC, Sevcsik E, Baumgart F, Stockinger H, Schütz GJ, Huppa JB, Brameshuber M. Unscrambling fluorophore blinking for comprehensive cluster detection via photoactivated localization microscopy. Nat Commun 2020; 11:4993. [PMID: 33020470 PMCID: PMC7536177 DOI: 10.1038/s41467-020-18726-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 09/10/2020] [Indexed: 12/22/2022] Open
Abstract
Determining nanoscale protein distribution via Photoactivated Localization Microscopy (PALM) mandates precise knowledge of the applied fluorophore's blinking properties to counteract overcounting artifacts that distort the resulting biomolecular distributions. Here, we present a readily applicable methodology to determine, optimize and quantitatively account for the blinking behavior of any PALM-compatible fluorophore. Using a custom-designed platform, we reveal complex blinking of two photoswitchable fluorescence proteins (PS-CFP2 and mEOS3.2) and two photoactivatable organic fluorophores (PA Janelia Fluor 549 and Abberior CAGE 635) with blinking cycles on time scales of several seconds. Incorporating such detailed information in our simulation-based analysis package allows for robust evaluation of molecular clustering based on individually recorded single molecule localization maps.
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Affiliation(s)
- René Platzer
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | | | | | - Eva Sevcsik
- Institute of Applied Physics, TU Wien, Vienna, Austria
| | | | - Hannes Stockinger
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | | | - Johannes B Huppa
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
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8
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Arnold AM, Schneider MC, Hüsson C, Sablatnig R, Brameshuber M, Baumgart F, Schütz GJ. Verifying molecular clusters by 2-color localization microscopy and significance testing. Sci Rep 2020; 10:4230. [PMID: 32144344 PMCID: PMC7060173 DOI: 10.1038/s41598-020-60976-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 02/17/2020] [Indexed: 11/08/2022] Open
Abstract
While single-molecule localization microscopy (SMLM) offers the invaluable prospect to visualize cellular structures below the diffraction limit of light microscopy, its potential has not yet been fully capitalized due to its inherent susceptibility to blinking artifacts. Particularly, overcounting of single molecule localizations has impeded a reliable and sensitive detection of biomolecular nanoclusters. Here we introduce a 2-Color Localization microscopy And Significance Testing Approach (2-CLASTA), providing a parameter-free statistical framework for the qualitative analysis of two-dimensional SMLM data via significance testing methods. 2-CLASTA yields p-values for the null hypothesis of random biomolecular distributions, independent of the blinking behavior of the chosen fluorescent labels. The method is parameter-free and does not require any additional measurements nor grouping of localizations. We validated the method both by computer simulations as well as experimentally, using protein concatemers as a mimicry of biomolecular clustering. As the new approach is not affected by overcounting artifacts, it is able to detect biomolecular clustering of various shapes at high sensitivity down to a level of dimers.
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Affiliation(s)
- Andreas M Arnold
- Institute of Applied Physics, TU Wien, Getreidemarkt 9, A-1060, Vienna, Austria
| | | | - Christoph Hüsson
- Institute of Visual Computing and Human-Centered Technology, TU Wien, Favoritenstrasse 9-11, A-1040, Vienna, Austria
| | - Robert Sablatnig
- Institute of Visual Computing and Human-Centered Technology, TU Wien, Favoritenstrasse 9-11, A-1040, Vienna, Austria
| | - Mario Brameshuber
- Institute of Applied Physics, TU Wien, Getreidemarkt 9, A-1060, Vienna, Austria
| | - Florian Baumgart
- Institute of Applied Physics, TU Wien, Getreidemarkt 9, A-1060, Vienna, Austria.
| | - Gerhard J Schütz
- Institute of Applied Physics, TU Wien, Getreidemarkt 9, A-1060, Vienna, Austria.
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9
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Bodner C, Brameshuber M, Schütz GJ. Determining the Oligomeric States of a GPI-Anchored Model Protein via Colocalization-Based Single-Molecule Microscopy. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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10
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Váradi T, Schneider M, Sevcsik E, Kiesenhofer D, Baumgart F, Batta G, Kovács T, Platzer R, Huppa JB, Szöllősi J, Schütz GJ, Brameshuber M, Nagy P. Homo- and Heteroassociations Drive Activation of ErbB3. Biophys J 2019; 117:1935-1947. [PMID: 31653451 PMCID: PMC7018998 DOI: 10.1016/j.bpj.2019.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 10/01/2019] [Accepted: 10/03/2019] [Indexed: 01/19/2023] Open
Abstract
Dimerization or the formation of higher-order oligomers is required for the activation of ErbB receptor tyrosine kinases. The heregulin (HRG) receptor, ErbB3, must heterodimerize with other members of the family, preferentially ErbB2, to form a functional signal transducing complex. Here, we applied single molecule imaging capable of detecting long-lived and mobile associations to measure their stoichiometry and mobility and analyzed data from experiments globally, taking the different lateral mobility of monomeric and dimeric molecular species into account. Although ErbB3 was largely monomeric in the absence of stimulation and ErbB2 co-expression, a small fraction was present as constitutive homodimers exhibiting a ∼40% lower mobility than monomers. HRG stimulation increased the homodimeric fraction of ErbB3 significantly and reduced the mobility of homodimers fourfold compared to constitutive homodimers. Expression of ErbB2 elevated the homodimeric fraction of ErbB3 even in unstimulated cells and induced a ∼2-fold reduction in the lateral mobility of ErbB3 homodimers. The mobility of ErbB2 was significantly lower than that of ErbB3, and HRG induced a less pronounced decrease in the diffusion coefficient of all ErbB2 molecules and ErbB3/ErbB2 heterodimers than in the mobility of ErbB3. The slower diffusion of ErbB2 compared to ErbB3 was abolished by depolymerizing actin filaments, whereas ErbB2 expression induced a substantial rearrangement of microfilaments, implying a bidirectional interaction between ErbB2 and actin. HRG stimulation of cells co-expressing ErbB3 and ErbB2 led to the formation of ErbB3 homodimers and ErbB3/ErbB2 heterodimers in a competitive fashion. Although pertuzumab, an antibody binding to the dimerization arm of ErbB2, completely abolished the formation of constitutive and HRG-induced ErbB3/ErbB2 heterodimers, it only slightly blocked ErbB3 homodimerization. The results imply that a dynamic equilibrium exists between constitutive and ligand-induced homo- and heterodimers capable of shaping transmembrane signaling.
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Affiliation(s)
- Tímea Váradi
- Institute of Applied Physics, TU Wien, Vienna, Austria; Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | | | - Eva Sevcsik
- Institute of Applied Physics, TU Wien, Vienna, Austria
| | | | | | - Gyula Batta
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; Department of Genetics and Applied Microbiology, Faculty of Science of Technology, University of Debrecen, Debrecen, Hungary
| | - Tamás Kovács
- Institute of Applied Physics, TU Wien, Vienna, Austria
| | - René Platzer
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Johannes B Huppa
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - János Szöllősi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | | | | | - Peter Nagy
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
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11
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Haselgrübler R, Lanzerstorfer P, Röhrl C, Stübl F, Schurr J, Schwarzinger B, Schwarzinger C, Brameshuber M, Wieser S, Winkler SM, Weghuber J. Hypolipidemic effects of herbal extracts by reduction of adipocyte differentiation, intracellular neutral lipid content, lipolysis, fatty acid exchange and lipid droplet motility. Sci Rep 2019; 9:10492. [PMID: 31324860 PMCID: PMC6642187 DOI: 10.1038/s41598-019-47060-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 07/05/2019] [Indexed: 12/12/2022] Open
Abstract
An increase in adipose tissue is caused by the increased size and number of adipocytes. Lipids accumulate in intracellular stores, known as lipid droplets (LDs). Recent studies suggest that parameters such as LD size, shape and dynamics are closely related to the development of obesity. Berberine (BBR), a natural plant alkaloid, has been demonstrated to possess anti-obesity effects. However, it remains unknown which cellular processes are affected by this compound or how effective herbal extracts containing BBR and other alkaloids actually are. For this study, we used extracts of Coptis chinensis, Mahonia aquifolium, Berberis vulgaris and Chelidonium majus containing BBR and other alkaloids and studied various processes related to adipocyte functionality. The presence of extracts resulted in reduced adipocyte differentiation, as well as neutral lipid content and rate of lipolysis. We observed that the intracellular fatty acid exchange was reduced in different LD size fractions upon treatment with BBR and Coptis chinensis. In addition, LD motility was decreased upon incubation with BBR, Coptis chinensis and Chelidonium majus extracts. Furthermore, Chelidonium majus was identified as a potent fatty acid uptake inhibitor. This is the first study that demonstrates the selected regulatory effects of herbal extracts on adipocyte function.
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Affiliation(s)
| | | | - Clemens Röhrl
- University of Applied Sciences Upper Austria, Wels, Austria.,Institute of Medical Chemistry, Center for Pathobiochemistry and Genetics, Medical University of Vienna, Vienna, Austria
| | - Flora Stübl
- University of Applied Sciences Upper Austria, Wels, Austria
| | - Jonas Schurr
- University of Applied Sciences Upper Austria, Hagenberg, Austria
| | - Bettina Schwarzinger
- Austrian Competence Center for Feed and Food Quality, Safety and Innovation, Wels, Austria
| | - Clemens Schwarzinger
- Johannes Kepler University, Institute for Chemical Technology of Organic Materials, Linz, Austria
| | | | - Stefan Wieser
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | | | - Julian Weghuber
- University of Applied Sciences Upper Austria, Wels, Austria. .,Austrian Competence Center for Feed and Food Quality, Safety and Innovation, Wels, Austria.
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12
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Abstract
Superresolution microscopy results have sparked the idea that many membrane proteins are not randomly distributed across the plasma membrane but are instead arranged in nanoclusters. Frequently, these new results seemed to confirm older data based on biochemical and electron microscopy experiments. Recently, however, it was recognized that multiple countings of the very same fluorescently labeled protein molecule can be easily confused with true protein clusters. Various strategies have been developed, which are intended to solve the problem of discriminating true protein clusters from imaging artifacts. We believe that there is currently no perfect algorithm for this problem; instead, different approaches have different strengths and weaknesses. In this review, we discuss single molecule localization microscopy in view of its ability to detect nanoclusters of membrane proteins. To capture the different views on nanoclustering, we chose an unconventional style for this article: we placed its scientific content in the setting of a fictive conference, where five researchers from different fields discuss the problem of detecting and quantifying nanoclusters. Using this style, we feel that the different approaches common for different research areas can be well illustrated. Similarities to a short story by Raymond Carver are not unintentional.
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13
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Plochberger B, Axmann M, Röhrl C, Weghuber J, Brameshuber M, Rossboth BK, Mayr S, Ros R, Bittman R, Stangl H, Schütz GJ. Direct observation of cargo transfer from HDL particles to the plasma membrane. Atherosclerosis 2018; 277:53-59. [PMID: 30173079 DOI: 10.1016/j.atherosclerosis.2018.08.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 07/02/2018] [Accepted: 08/24/2018] [Indexed: 10/28/2022]
Abstract
BACKGROUND AND AIMS Exchange of cholesterol between high-density lipoprotein (HDL) particles and cells is a key process for maintaining cellular cholesterol homeostasis. Recently, we have shown that amphiphilic cargo derived from HDL can be transferred directly to lipid bilayers. Here we pursued this work using a fluorescence-based method to directly follow cargo transfer from HDL particles to the cell membrane. METHODS HDL was either immobilized on surfaces or added directly to cells, while transfer of fluorescent cargo was visualized via fluorescence imaging. RESULTS In Chinese hamster ovary (CHO) cells expressing the scavenger receptor class B type 1 (SR-B1), transfer of amphiphilic cargo from HDL particles to the plasma membrane was observed immediately after contact, whereas hydrophobic cargo remained associated with the particles; about 60% of the amphiphilic cargo of surface-bound HDL was transferred to the plasma membrane. Essentially no cargo transfer was observed in cells with low endogenous SR-B1 expression. Interestingly, transfer of fluorescently-labeled cholesterol was also facilitated by using an artificial linker to bind HDL to the cell surface. CONCLUSIONS Our data hence indicate that the tethering function of SR-B1 is sufficient for efficient transfer of free cholesterol to the plasma membrane.
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Affiliation(s)
- Birgit Plochberger
- TU Wien, Institute of Applied Physics, Vienna, 1040, Austria; Upper Austria University of Applied Sciences, Campus Linz, Garnisonstrasse 21, 4020, Linz, Austria
| | - Markus Axmann
- Medical University of Vienna, Center for Pathobiochemistry and Genetics, Institute of Medical Chemistry, Vienna, 1090, Austria
| | - Clemens Röhrl
- Medical University of Vienna, Center for Pathobiochemistry and Genetics, Institute of Medical Chemistry, Vienna, 1090, Austria
| | - Julian Weghuber
- Upper Austria University of Applied Sciences, Campus Wels, Stelzhamerstraße 23, 4600, Wels, Austria
| | | | | | - Sandra Mayr
- Upper Austria University of Applied Sciences, Campus Linz, Garnisonstrasse 21, 4020, Linz, Austria
| | - Robert Ros
- Arizona State University, Department of Physics, Tempe, AZ, 85287-1504, USA
| | - Robert Bittman
- Queens College of the City University of New York, Department of Chemistry and Biochemistry, Flushing, NY, 11367, USA
| | - Herbert Stangl
- Medical University of Vienna, Center for Pathobiochemistry and Genetics, Institute of Medical Chemistry, Vienna, 1090, Austria.
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14
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Rossboth B, Arnold AM, Ta H, Platzer R, Kellner F, Huppa JB, Brameshuber M, Baumgart F, Schütz GJ. TCRs are randomly distributed on the plasma membrane of resting antigen-experienced T cells. Nat Immunol 2018; 19:821-827. [PMID: 30013143 PMCID: PMC6071872 DOI: 10.1038/s41590-018-0162-7] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 06/14/2018] [Indexed: 12/29/2022]
Abstract
The main function of T cells is to identify harmful antigens as quickly and precisely as possible. Super-resolution microscopy data have indicated that global clustering of T cell antigen receptors (TCRs) occurs before T cell activation. Such pre-activation clustering has been interpreted as representing a potential regulatory mechanism that fine tunes the T cell response. We found here that apparent TCR nanoclustering could be attributed to overcounting artifacts inherent to single-molecule-localization microscopy. Using complementary super-resolution approaches and statistical image analysis, we found no indication of global nanoclustering of TCRs on antigen-experienced CD4+ T cells under non-activating conditions. We also used extensive simulations of super-resolution images to provide quantitative limits for the degree of randomness of the TCR distribution. Together our results suggest that the distribution of TCRs on the plasma membrane is optimized for fast recognition of antigen in the first phase of T cell activation.
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Affiliation(s)
| | | | - Haisen Ta
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - René Platzer
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Florian Kellner
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Johannes B Huppa
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
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15
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Fülöp G, Brameshuber M, Arnold AM, Schütz GJ, Sevcsik E. Determination of the Membrane Environment of CD59 in Living Cells. Biomolecules 2018; 8:E28. [PMID: 29772810 PMCID: PMC6023084 DOI: 10.3390/biom8020028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 04/24/2018] [Accepted: 05/14/2018] [Indexed: 11/24/2022] Open
Abstract
The organization and dynamics of proteins and lipids in the plasma membrane, and their role in membrane functionality, have been subject of a long-lasting debate. Specifically, it is unclear to what extent membrane proteins are affected by their immediate lipid environment and vice versa. Studies on model membranes and plasma membrane vesicles indicated preferences of proteins for lipid phases characterized by different acyl chain order; however, whether such phases do indeed exist in live cells is still not known. Here, we refine a previously developed micropatterning approach combined with single molecule tracking to quantify the influence of the glycosylphosphatidylinositol-anchored (GPI-anchored) protein CD59 on its molecular environment directly in the live cell plasma membrane. We find that locally enriched and immobilized CD59 presents obstacles to the diffusion of fluorescently labeled lipids with a different phase-partitioning behavior independent of cell cholesterol levels and type of lipid. Our results give no evidence for either specific binding of the lipids to CD59 or the existence of nanoscopic ordered membrane regions associated with CD59.
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Affiliation(s)
- Gergő Fülöp
- Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria.
| | - Mario Brameshuber
- Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria.
| | - Andreas M Arnold
- Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria.
| | - Gerhard J Schütz
- Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria.
| | - Eva Sevcsik
- Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria.
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16
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Brameshuber M, Kellner F, Rossboth BK, Ta H, Alge K, Sevcsik E, Göhring J, Axmann M, Baumgart F, Gascoigne NRJ, Davis SJ, Stockinger H, Schütz GJ, Huppa JB. Monomeric TCRs drive T cell antigen recognition. Nat Immunol 2018; 19:487-496. [PMID: 29662172 DOI: 10.1038/s41590-018-0092-4] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 03/15/2018] [Indexed: 11/09/2022]
Abstract
T cell antigen recognition requires T cell antigen receptors (TCRs) engaging MHC-embedded antigenic peptides (pMHCs) within the contact region of a T cell with its conjugated antigen-presenting cell. Despite micromolar TCR:pMHC affinities, T cells respond to even a single antigenic pMHC, and higher-order TCRs have been postulated to maintain high antigen sensitivity and trigger signaling. We interrogated the stoichiometry of TCRs and their associated CD3 subunits on the surface of living T cells through single-molecule brightness and single-molecule coincidence analysis, photon-antibunching-based fluorescence correlation spectroscopy and Förster resonance energy transfer measurements. We found exclusively monomeric TCR-CD3 complexes driving the recognition of antigenic pMHCs, which underscores the exceptional capacity of single TCR-CD3 complexes to elicit robust intracellular signaling.
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Affiliation(s)
| | - Florian Kellner
- Center for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria
| | | | - Haisen Ta
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Kevin Alge
- Center for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria
| | - Eva Sevcsik
- Institute of Applied Physics, TU Wien, Vienna, Austria
| | - Janett Göhring
- Institute of Applied Physics, TU Wien, Vienna, Austria.,Center for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria
| | - Markus Axmann
- Center for Pathobiochemistry and Genetics, Institute of Medical Chemistry and Pathobiochemistry, Medical University of Vienna, Vienna, Austria
| | | | - Nicholas R J Gascoigne
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Simon J Davis
- Radcliffe Department of Medicine and MRC Human Immunology Unit, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Hannes Stockinger
- Center for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria
| | | | - Johannes B Huppa
- Center for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria.
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17
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Brameshuber M, Kellner F, Rossboth BK, Ta H, Alge K, Sevcsik E, Axmann M, Gascoigne NR, Davis SJ, Stockinger H, Schuetz GJ, Huppa JB. Monomeric TCR-CD3 Complexes Drive T-Cell Antigen Recognition. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.626] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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18
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Baumgart F, Rossboth BK, Arnold AM, Brameshuber M, Ta H, Platzer R, Huppa JB, Schütz GJ. Superresolution Microscopy of the T Cell Receptor in the Immunological Synapse. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.2923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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19
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Plochberger B, Röhrl C, Preiner J, Rankl C, Brameshuber M, Madl J, Bittman R, Ros R, Sezgin E, Eggeling C, Hinterdorfer P, Stangl H, Schütz GJ. HDL particles incorporate into lipid bilayers - a combined AFM and single molecule fluorescence microscopy study. Sci Rep 2017; 7:15886. [PMID: 29162870 PMCID: PMC5698431 DOI: 10.1038/s41598-017-15949-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 11/03/2017] [Indexed: 11/09/2022] Open
Abstract
The process, how lipids are removed from the circulation and transferred from high density lipoprotein (HDL) – a main carrier of cholesterol in the blood stream – to cells, is highly complex. HDL particles are captured from the blood stream by the scavenger receptor, class B, type I (SR-BI), the so-called HDL receptor. The details in subsequent lipid-transfer process, however, have not yet been completely understood. The transfer has been proposed to occur directly at the cell surface across an unstirred water layer, via a hydrophobic channel in the receptor, or after HDL endocytosis. The role of the target lipid membrane for the transfer process, however, has largely been overlooked. Here, we studied at the single molecule level how HDL particles interact with synthetic lipid membranes. Using (high-speed) atomic force microscopy and fluorescence correlation spectroscopy (FCS) we found out that, upon contact with the membrane, HDL becomes integrated into the lipid bilayer. Combined force and single molecule fluorescence microscopy allowed us to directly monitor the transfer process of fluorescently labelled amphiphilic lipid probe from HDL particles to the lipid bilayer upon contact.
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Affiliation(s)
- Birgit Plochberger
- TU Wien, Institute of Applied Physics, Vienna, 1040, Austria.,Johannes Kepler University Linz, Institute of Biophysics, Linz, 4020, Austria.,Upper Austria University of Applied Sciences, Campus Linz, Linz, 4020, Austria
| | - Clemens Röhrl
- Medical University of Vienna, Center for Pathobiochemistry and Genetics, Institute of Medical Chemistry, Vienna, 1090, Austria
| | - Johannes Preiner
- Upper Austria University of Applied Sciences, Campus Linz, Linz, 4020, Austria.,Center for Advanced Bioanalysis GmbH, Linz, 4020, Austria
| | | | | | - Josef Madl
- Johannes Kepler University Linz, Institute of Biophysics, Linz, 4020, Austria
| | - Robert Bittman
- Queens College of the City University of New York, Department of Chemistry and Biochemistry, Flushing, NY, 11367, USA
| | - Robert Ros
- Arizona State University, Department of Physics, Tempe, AZ, 85287-1504, USA
| | - Erdinc Sezgin
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, 01307, Germany.,MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Christian Eggeling
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Peter Hinterdorfer
- Johannes Kepler University Linz, Institute of Biophysics, Linz, 4020, Austria
| | - Herbert Stangl
- Medical University of Vienna, Center for Pathobiochemistry and Genetics, Institute of Medical Chemistry, Vienna, 1090, Austria.
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20
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Peksel B, Gombos I, Péter M, Vigh L, Tiszlavicz Á, Brameshuber M, Balogh G, Schütz GJ, Horváth I, Vigh L, Török Z. Mild heat induces a distinct "eustress" response in Chinese Hamster Ovary cells but does not induce heat shock protein synthesis. Sci Rep 2017; 7:15643. [PMID: 29142280 PMCID: PMC5688065 DOI: 10.1038/s41598-017-15821-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 11/02/2017] [Indexed: 11/16/2022] Open
Abstract
The current research on cellular heat stress management focuses on the roles of heat shock proteins (HSPs) and the proteostasis network under severe stress conditions. The mild, fever-type stress and the maintenance of membrane homeostasis are less well understood. Herein, we characterized the acute effect of mild, fever-range heat shock on membrane organization, and HSP synthesis and localization in two mammalian cell lines, to delineate the role of membranes in the sensing and adaptation to heat. A multidisciplinary approach combining ultrasensitive fluorescence microscopy and lipidomics revealed the molecular details of novel cellular “eustress”, when cells adapt to mild heat by maintaining membrane homeostasis, activating lipid remodeling, and redistributing chaperone proteins. Notably, this leads to acquired thermotolerance in the complete absence of the induction of HSPs. At higher temperatures, additional defense mechanisms are activated, including elevated expression of molecular chaperones, contributing to an extended stress memory and acquired thermotolerance.
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Affiliation(s)
- Begüm Peksel
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, H-6726, Hungary
| | - Imre Gombos
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, H-6726, Hungary
| | - Mária Péter
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, H-6726, Hungary
| | - László Vigh
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, H-6726, Hungary
| | - Ádám Tiszlavicz
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, H-6726, Hungary
| | - Mario Brameshuber
- Institute of Applied Physics - Biophysics, TU Wien, 1040, Vienna, Austria
| | - Gábor Balogh
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, H-6726, Hungary
| | - Gerhard J Schütz
- Institute of Applied Physics - Biophysics, TU Wien, 1040, Vienna, Austria
| | - Ibolya Horváth
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, H-6726, Hungary
| | - László Vigh
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, H-6726, Hungary
| | - Zsolt Török
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, H-6726, Hungary.
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21
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Brameshuber M, Sevcsik E, Rossboth BK, Manner C, Deigner HP, Peksel B, Péter M, Török Z, Hermetter A, Schütz GJ. Oxidized Phospholipids Inhibit the Formation of Cholesterol-Dependent Plasma Membrane Nanoplatforms. Biophys J 2016; 110:205-13. [PMID: 26745423 DOI: 10.1016/j.bpj.2015.11.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 10/14/2015] [Accepted: 11/13/2015] [Indexed: 01/08/2023] Open
Abstract
We previously developed a single-molecule microscopy method termed TOCCSL (thinning out clusters while conserving stoichiometry of labeling), which allows for direct imaging of stable nanoscopic platforms with raft-like properties diffusing in the plasma membrane. As a consensus raft marker, we chose monomeric GFP linked via a glycosylphosphatidylinositol (GPI) anchor to the cell membrane (mGFP-GPI). With this probe, we previously observed cholesterol-dependent homo-association to nanoplatforms diffusing in the plasma membrane of live CHO cells. Here, we report the release of this homo-association upon addition of 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine (POVPC) or 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphocholine, two oxidized phospholipids (oxPLs) that are typically present in oxidatively modified low-density lipoprotein. We found a dose-response relationship for mGFP-GPI nanoplatform disintegration upon addition of POVPC, correlating with the signal of the apoptosis marker Annexin V-Cy3. Similar concentrations of lysolipid showed no effect, indicating that the observed phenomena were not linked to properties of the lipid bilayer itself. Inhibition of acid sphingomyelinase by NB-19 before addition of POVPC completely abolished nanoplatform disintegration by oxPLs. In conclusion, we were able to determine how oxidized lipid species disrupt mGFP-GPI nanoplatforms in the plasma membrane. Our results favor an indirect mechanism involving acid sphingomyelinase activity rather than a direct interaction of oxPLs with nanoplatform constituents.
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Affiliation(s)
| | - Eva Sevcsik
- Institute of Applied Physics, TU Wien, Vienna, Austria
| | | | | | - Hans-Peter Deigner
- Faculty of Medical and Life Sciences, Institute of Precision Medicine, Furtwangen University, Villingen-Schwenningen, Germany; Fraunhofer Institute IZI/EXIM, Furtwangen, Germany
| | - Begüm Peksel
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Mária Péter
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zsolt Török
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Albin Hermetter
- Institute of Biochemistry, Graz University of Technology, Graz, Austria
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22
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Sevcsik E, Brameshuber M, Fölser M, Weghuber J, Honigmann A, Schütz GJ. GPI-anchored proteins do not reside in ordered domains in the live cell plasma membrane. Nat Commun 2015; 6:6969. [PMID: 25897971 PMCID: PMC4430820 DOI: 10.1038/ncomms7969] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 03/18/2015] [Indexed: 02/07/2023] Open
Abstract
The organization of proteins and lipids in the plasma membrane has been the subject of a long-lasting debate. Membrane rafts of higher lipid chain order were proposed to mediate protein interactions, but have thus far not been directly observed. Here we use protein micropatterning combined with single-molecule tracking to put current models to the test: we rearranged lipid-anchored raft proteins (glycosylphosphatidylinositol(GPI)-anchored-mGFP) directly in the live cell plasma membrane and measured the effect on the local membrane environment. Intriguingly, this treatment does neither nucleate the formation of an ordered membrane phase nor result in any enrichment of nanoscopic-ordered domains within the micropatterned regions. In contrast, we find that immobilized mGFP-GPIs behave as inert obstacles to the diffusion of other membrane constituents without influencing their membrane environment over distances beyond their physical size. Our results indicate that phase partitioning is not a fundamental element of protein organization in the plasma membrane.
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Affiliation(s)
- Eva Sevcsik
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria
| | - Mario Brameshuber
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria
| | - Martin Fölser
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria
| | - Julian Weghuber
- School of Engineering and Environmental Sciences, University of Applied Sciences Upper Austria, Stelzhamerstrasse 23, Wels 4600, Austria
| | - Alf Honigmann
- Department of NanoBiophotonics, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany
| | - Gerhard J Schütz
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria
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23
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Lamprecht C, Plochberger B, Ruprecht V, Wieser S, Rankl C, Heister E, Unterauer B, Brameshuber M, Danzberger J, Lukanov P, Flahaut E, Schütz G, Hinterdorfer P, Ebner A. A single-molecule approach to explore binding, uptake and transport of cancer cell targeting nanotubes. Nanotechnology 2014; 25:125704. [PMID: 24577143 DOI: 10.1088/0957-4484/25/12/125704] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In the past decade carbon nanotubes (CNTs) have been widely studied as a potential drug-delivery system, especially with functionality for cellular targeting. Yet, little is known about the actual process of docking to cell receptors and transport dynamics after internalization. Here we performed single-particle studies of folic acid (FA) mediated CNT binding to human carcinoma cells and their transport inside the cytosol. In particular, we employed molecular recognition force spectroscopy, an atomic force microscopy based method, to visualize and quantify docking of FA functionalized CNTs to FA binding receptors in terms of binding probability and binding force. We then traced individual fluorescently labeled, FA functionalized CNTs after specific uptake, and created a dynamic 'roadmap' that clearly showed trajectories of directed diffusion and areas of nanotube confinement in the cytosol. Our results demonstrate the potential of a single-molecule approach for investigation of drug-delivery vehicles and their targeting capacity.
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Affiliation(s)
- C Lamprecht
- Institute of Biophysics, Johannes Kepler University, A-4020 Linz, Austria. Institute of Materials Science, Christian-Albrechts-University of Kiel, D-24114 Kiel, Germany
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24
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Anderluh A, Klotzsch E, Reismann AWAF, Brameshuber M, Kudlacek O, Newman AH, Sitte HH, Schütz GJ. Single molecule analysis reveals coexistence of stable serotonin transporter monomers and oligomers in the live cell plasma membrane. J Biol Chem 2014; 289:4387-94. [PMID: 24394416 DOI: 10.1074/jbc.m113.531632] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The human serotonin transporter (hSERT) is responsible for the termination of synaptic serotonergic signaling. Although there is solid evidence that SERT forms oligomeric complexes, the exact stoichiometry of the complexes and the fractions of different coexisting oligomeric states still remain enigmatic. Here we used single molecule fluorescence microscopy to obtain the oligomerization state of the SERT via brightness analysis of single diffraction-limited fluorescent spots. Heterologously expressed SERT was labeled either with the fluorescent inhibitor JHC 1-64 or via fusion to monomeric GFP. We found a variety of oligomerization states of membrane-associated transporters, revealing molecular associations larger than dimers and demonstrating the coexistence of different degrees of oligomerization in a single cell; the data are in agreement with a linear aggregation model. Furthermore, oligomerization was found to be independent of SERT surface density, and oligomers remained stable over several minutes in the live cell plasma membrane. Together, the results indicate kinetic trapping of preformed SERT oligomers at the plasma membrane.
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Affiliation(s)
- Andreas Anderluh
- From the Institute of Applied Physics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
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25
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Sevcsik E, Brameshuber M, Fölser M, Schütz GJ. Creating Obstacle Courses for Raft Proteins - How Micropatterning Can Help Decipher Plasma Membrane Organization. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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26
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Plochberger B, Schuetz GJ, Röhrl C, Preiner J, Sezgin E, Brameshuber M, Weghuber J, Wieser S, Rankl C, Ruprecht V, Madl J, Bittman R, Hinterdorfer P, Stangl H. HDL-Lipid Uptake is Regulated by Elastic Properties of the Plasma Membrane. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.2216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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27
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Török Z, Crul T, Maresca B, Schütz GJ, Viana F, Dindia L, Piotto S, Brameshuber M, Balogh G, Péter M, Porta A, Trapani A, Gombos I, Glatz A, Gungor B, Peksel B, Vigh L, Csoboz B, Horváth I, Vijayan MM, Hooper PL, Harwood JL, Vigh L. Plasma membranes as heat stress sensors: from lipid-controlled molecular switches to therapeutic applications. Biochim Biophys Acta 2013; 1838:1594-618. [PMID: 24374314 DOI: 10.1016/j.bbamem.2013.12.015] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 12/09/2013] [Accepted: 12/18/2013] [Indexed: 12/31/2022]
Abstract
The classic heat shock (stress) response (HSR) was originally attributed to protein denaturation. However, heat shock protein (Hsp) induction occurs in many circumstances where no protein denaturation is observed. Recently considerable evidence has been accumulated to the favor of the "Membrane Sensor Hypothesis" which predicts that the level of Hsps can be changed as a result of alterations to the plasma membrane. This is especially pertinent to mild heat shock, such as occurs in fever. In this condition the sensitivity of many transient receptor potential (TRP) channels is particularly notable. Small temperature stresses can modulate TRP gating significantly and this is influenced by lipids. In addition, stress hormones often modify plasma membrane structure and function and thus initiate a cascade of events, which may affect HSR. The major transactivator heat shock factor-1 integrates the signals originating from the plasma membrane and orchestrates the expression of individual heat shock genes. We describe how these observations can be tested at the molecular level, for example, with the use of membrane perturbers and through computational calculations. An important fact which now starts to be addressed is that membranes are not homogeneous nor do all cells react identically. Lipidomics and cell profiling are beginning to address the above two points. Finally, we observe that a deregulated HSR is found in a large number of important diseases where more detailed knowledge of the molecular mechanisms involved may offer timely opportunities for clinical interventions and new, innovative drug treatments. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.
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Affiliation(s)
- Zsolt Török
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary.
| | - Tim Crul
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Bruno Maresca
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Salerno, Italy
| | - Gerhard J Schütz
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria
| | - Felix Viana
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, 03550 San Juan de Alicante, Spain
| | - Laura Dindia
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Stefano Piotto
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Salerno, Italy
| | - Mario Brameshuber
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria
| | - Gábor Balogh
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Mária Péter
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Amalia Porta
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Salerno, Italy
| | - Alfonso Trapani
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Salerno, Italy
| | - Imre Gombos
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Attila Glatz
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Burcin Gungor
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Begüm Peksel
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - László Vigh
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Bálint Csoboz
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Ibolya Horváth
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Mathilakath M Vijayan
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada; Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Phillip L Hooper
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Medical School, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - John L Harwood
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, Wales, UK
| | - László Vigh
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary.
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28
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Huang J, Brameshuber M, Zeng X, Xie J, Li QJ, Chien YH, Valitutti S, Davis MM. A single peptide-major histocompatibility complex ligand triggers digital cytokine secretion in CD4(+) T cells. Immunity 2013; 39:846-57. [PMID: 24120362 DOI: 10.1016/j.immuni.2013.08.036] [Citation(s) in RCA: 251] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 08/02/2013] [Indexed: 11/26/2022]
Abstract
We have developed a single-molecule imaging technique that uses quantum-dot-labeled peptide-major histocompatibility complex (pMHC) ligands to study CD4(+) T cell functional sensitivity. We found that naive T cells, T cell blasts, and memory T cells could all be triggered by a single pMHC to secrete tumor necrosis factor-α (TNF-α) and interleukin-2 (IL-2) cytokines with a rate of ∼1,000, ∼10,000, and ∼10,000 molecules/min, respectively, and that additional pMHCs did not augment secretion, indicating a digital response pattern. We also found that a single pMHC localized to the immunological synapse induced the slow formation of a long-lasting T cell receptor (TCR) cluster, consistent with a serial engagement mechanism. These data show that scaling up CD4(+) T cell cytokine responses involves increasingly efficient T cell recruitment rather than greater cytokine production per cell.
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Affiliation(s)
- Jun Huang
- Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305, USA
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29
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Brameshuber M, Salzlechner C, Weghuber J, Platzer R, Huppa JB, Schutz GJ. Techniques for Direct Imaging of Nanoplatforms in the Live Cell Plasma Membrane. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.1383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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30
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Sevcsik E, Sunzenauer S, Brameshuber M, Schutz GJ. Protein Micropatterning in Live Cells: A Tool for Creating Membrane Domains with Raft-Like Properties. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.1081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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31
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Preiner J, Kodera N, Tang J, Ebner A, Brameshuber M, Blaas D, Ilk N, Gruber HJ, Ando T, Hinterdorfer P. Antibody Movement on Regular Antigen Clusters: Fab Arms are made for Walking. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.2122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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32
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Sunzenauer S, Zojer V, Brameshuber M, Tröls A, Weghuber J, Stockinger H, Schütz GJ. Determination of binding curves via protein micropatterning in vitro and in living cells. Cytometry A 2012; 83:847-54. [PMID: 23125142 DOI: 10.1002/cyto.a.22225] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/23/2012] [Accepted: 10/09/2012] [Indexed: 11/11/2022]
Abstract
Quantification of protein interactions in living cells is of key relevance for understanding cellular signaling. With current techniques, however, it is difficult to determine binding affinities and stoichiometries of protein complexes in the plasma membrane. We introduce here protein micropatterning as a convenient and versatile method for such investigations. Cells are grown on surfaces containing micropatterns of capture antibody to a bait protein, so that the bait gets rearranged in the live cell plasma membrane. Upon interaction with the bait, the fluorescent prey follows the micropatterns, which can be readout with fluorescence microscopy. In this study, we addressed the interaction between Lck and CD4, two central proteins in early T-cell signaling. Binding curves were recorded using the natural fluctuations in the Lck expression levels. Surprisingly, the binding was not saturable up to the highest Lck expression levels: on average, a single CD4 molecule recruited more than nine Lck molecules. We discuss the data in view of protein- and lipid-mediated interactions.
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Affiliation(s)
- Stefan Sunzenauer
- Biophysics Institute, Johannes Kepler University Linz, A-4040 Linz, Austria
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33
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Lamprecht C, Gierlinger N, Heister E, Unterauer B, Plochberger B, Brameshuber M, Hinterdorfer P, Hild S, Ebner A. Mapping the intracellular distribution of carbon nanotubes after targeted delivery to carcinoma cells using confocal Raman imaging as a label-free technique. J Phys Condens Matter 2012; 24:164206. [PMID: 22466107 DOI: 10.1088/0953-8984/24/16/164206] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The uptake of carbon nanotubes (CNTs) by mammalian cells and their distribution within cells is being widely studied in recent years due to their increasing use for biomedical purposes. The two main imaging techniques used are confocal fluorescence microscopy and transmission electron microscopy (TEM). The former, however, requires labeling of the CNTs with fluorescent dyes, while the latter is a work-intensive technique that is unsuitable for in situ bio-imaging. Raman spectroscopy, on the other hand, presents a direct, straightforward and label-free alternative. Confocal Raman microscopy can be used to image the CNTs inside cells, exploiting the strong Raman signal connected to different vibrational modes of the nanotubes. In addition, cellular components, such as the endoplasmic reticulum and the nucleus, can be mapped. We first validate our method by showing that only when using the CNTs' G band for intracellular mapping accurate results can be obtained, as mapping of the radial breathing mode (RBM) only shows a small fraction of CNTs. We then take a closer look at the exact localization of the nanotubes inside cells after folate receptor-mediated endocytosis and show that, after 8-10 h incubation, the majority of CNTs are localized around the nucleus. In summary, Raman imaging has enormous potential for imaging CNTs inside cells, which is yet to be fully realized.
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Affiliation(s)
- C Lamprecht
- Institute of Biophysics, J Kepler University, Linz, Austria.
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34
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Sunzenauer S, Brameshuber M, Weghuber J, Schuetz GJ. Protein Micropatterning in the Plasma Membrane Allows for Kd Determination in Living Cells and Superresolution Analysis of Lipid Rafts. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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35
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Abstract
During their random motion, biomolecules experience a manifold of interactions that transiently conjoin their paths. It is extremely difficult to measure such binding events directly in the context of a living cell: interactions may be short lived, they may affect only a minority fraction of molecules, or they may not lead to a macroscopically observable effect. We describe here a new single-molecule imaging method that allows for detecting and quantifying associations of mobile molecules. By "thinning out clusters while conserving the stoichiometry of labeling" (TOCCSL), we can virtually dilute the probe directly in the cell, without affecting the fluorescence labeling of single clusters. Essentially, an analysis region is created within the cell by photobleaching; this region is devoid of active probe. Brownian diffusion or other transport processes lead to reentry of active probe into the analysis region. At the onset of the recovery process, single spots can be resolved as well-separated, diffraction-limited signals. Standard single-molecule microscopy then allows for characterizing the spots in terms of their composition and mobility.
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Affiliation(s)
- Mario Brameshuber
- Biophysics Institute, Johannes Kepler University Linz, Altenbergerstr., Linz, Austria
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36
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Plochberger B, Röhrl C, Brameshuber M, Weghuber J, Rankl C, Kaur P, Madl J, Ros R, Lindsay SM, Hinterdorfer P, Stangl H, Schütz GJ. Combined Single Molecule Fluorescence and Force Microscopy to Study Lipid Transfer from Lipoproteins to Biomembranes. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.2290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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37
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Gombos I, Crul T, Piotto S, Güngör B, Török Z, Balogh G, Péter M, Slotte JP, Campana F, Pilbat AM, Hunya Á, Tóth N, Literati-Nagy Z, Vígh L, Glatz A, Brameshuber M, Schütz GJ, Hevener A, Febbraio MA, Horváth I, Vígh L. Membrane-lipid therapy in operation: the HSP co-inducer BGP-15 activates stress signal transduction pathways by remodeling plasma membrane rafts. PLoS One 2011; 6:e28818. [PMID: 22174906 PMCID: PMC3236211 DOI: 10.1371/journal.pone.0028818] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 11/15/2011] [Indexed: 01/22/2023] Open
Abstract
Aging and pathophysiological conditions are linked to membrane changes which modulate membrane-controlled molecular switches, causing dysregulated heat shock protein (HSP) expression. HSP co-inducer hydroxylamines such as BGP-15 provide advanced therapeutic candidates for many diseases since they preferentially affect stressed cells and are unlikely have major side effects. In the present study in vitro molecular dynamic simulation, experiments with lipid monolayers and in vivo ultrasensitive fluorescence microscopy showed that BGP-15 alters the organization of cholesterol-rich membrane domains. Imaging of nanoscopic long-lived platforms using the raft marker glycosylphosphatidylinositol-anchored monomeric green fluorescent protein diffusing in the live Chinese hamster ovary (CHO) cell plasma membrane demonstrated that BGP-15 prevents the transient structural disintegration of rafts induced by fever-type heat stress. Moreover, BGP-15 was able to remodel cholesterol-enriched lipid platforms reminiscent of those observed earlier following non-lethal heat priming or membrane stress, and were shown to be obligate for the generation and transmission of stress signals. BGP-15 activation of HSP expression in B16-F10 mouse melanoma cells involves the Rac1 signaling cascade in accordance with the previous observation that cholesterol affects the targeting of Rac1 to membranes. Finally, in a human embryonic kidney cell line we demonstrate that BGP-15 is able to inhibit the rapid heat shock factor 1 (HSF1) acetylation monitored during the early phase of heat stress, thereby promoting a prolonged duration of HSF1 binding to heat shock elements. Taken together, our results indicate that BGP-15 has the potential to become a new class of pharmaceuticals for use in ‘membrane-lipid therapy’ to combat many various protein-misfolding diseases associated with aging.
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Affiliation(s)
- Imre Gombos
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Tim Crul
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Stefano Piotto
- Department of Pharmaceutical and Biomedical Sciences, University of Salerno, Salerno, Italy
| | - Burcin Güngör
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zsolt Török
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Gábor Balogh
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Mária Péter
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - J. Peter Slotte
- Department of Biosciences, Abo Akademi University, Turku, Finland
| | - Federica Campana
- Department of Pharmaceutical and Biomedical Sciences, University of Salerno, Salerno, Italy
| | - Ana-Maria Pilbat
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | | | - Noémi Tóth
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zsuzsanna Literati-Nagy
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - László Vígh
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
- * E-mail:
| | - Attila Glatz
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Mario Brameshuber
- Institute of Applied Physics, Vienna University of Technology, Vienna, Austria
| | - Gerhard J. Schütz
- Institute of Applied Physics, Vienna University of Technology, Vienna, Austria
| | - Andrea Hevener
- Department of Medicine, Division of Endocrinology, University of California, Los Angeles, Los Angeles, California, United States of America
| | - Mark A. Febbraio
- Cellular and Molecular Metabolism Laboratory, Baker Heart and Diabetes Institute, Prahran, Victoria, Australia
| | - Ibolya Horváth
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - László Vígh
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
- * E-mail:
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38
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Weghuber J, Aichinger MC, Brameshuber M, Wieser S, Ruprecht V, Plochberger B, Madl J, Horner A, Reipert S, Lohner K, Henics T, Schütz GJ. Cationic amphipathic peptides accumulate sialylated proteins and lipids in the plasma membrane of eukaryotic host cells. Biochim Biophys Acta 2011; 1808:2581-90. [PMID: 21718688 PMCID: PMC3161180 DOI: 10.1016/j.bbamem.2011.06.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 06/08/2011] [Accepted: 06/13/2011] [Indexed: 11/25/2022]
Abstract
Cationic antimicrobial peptides (CAMPs) selectively target bacterial membranes by electrostatic interactions with negatively charged lipids. It turned out that for inhibition of microbial growth a high CAMP membrane concentration is required, which can be realized by the incorporation of hydrophobic groups within the peptide. Increasing hydrophobicity, however, reduces the CAMP selectivity for bacterial over eukaryotic host membranes, thereby causing the risk of detrimental side-effects. In this study we addressed how cationic amphipathic peptides—in particular a CAMP with Lysine–Leucine–Lysine repeats (termed KLK)—affect the localization and dynamics of molecules in eukaryotic membranes. We found KLK to selectively inhibit the endocytosis of a subgroup of membrane proteins and lipids by electrostatically interacting with negatively charged sialic acid moieties. Ultrastructural characterization revealed the formation of membrane invaginations representing fission or fusion intermediates, in which the sialylated proteins and lipids were immobilized. Experiments on structurally different cationic amphipathic peptides (KLK, 6-MO-LF11-322 and NK14-2) indicated a cooperation of electrostatic and hydrophobic forces that selectively arrest sialylated membrane constituents.
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Affiliation(s)
- Julian Weghuber
- Biophysics Institute, Johannes Kepler University Linz, Altenbergerstr 69, A-4040 Linz, Austria.
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Brameshuber M, Weghuber J, Ruprecht V, Gombos I, Horváth I, Vigh L, Eckerstorfer P, Kiss E, Stockinger H, Schütz GJ. Imaging of mobile long-lived nanoplatforms in the live cell plasma membrane. J Biol Chem 2010; 285:41765-71. [PMID: 20966075 PMCID: PMC3009904 DOI: 10.1074/jbc.m110.182121] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2010] [Revised: 10/18/2010] [Indexed: 11/06/2022] Open
Abstract
The plasma membrane has been hypothesized to contain nanoscopic lipid platforms, which are discussed in the context of "lipid rafts" or "membrane rafts." Based on biochemical and cell biological studies, rafts are believed to play a crucial role in many signaling processes. However, there is currently not much information on their size, shape, stability, surface density, composition, and heterogeneity. We present here a method that allows for the first time the direct imaging of nanoscopic long-lived platforms with raft-like properties diffusing in the live cell plasma membrane. Our method senses these platforms by their property to assemble a characteristic set of fluorescent marker proteins or lipids on a time scale of seconds. A special photobleaching protocol was used to reduce the surface density of labeled mobile platforms down to the level of well isolated diffraction-limited spots without altering the single spot brightness. The statistical distribution of probe molecules per platform was determined by single molecule brightness analysis. For demonstration, we used the consensus raft marker glycosylphosphatidylinositol-anchored monomeric GFP and the fluorescent lipid analog BODIPY-G(M1), which preferentially partitions into liquid-ordered phases. For both markers, we found cholesterol-dependent homo-association in the plasma membrane of living CHO and Jurkat T cells in the resting state, thereby demonstrating the existence of small, mobile, long-lived platforms containing these probes. We further applied the technology to address structural changes in the plasma membrane during fever-type heat shock: at elevated temperatures, the glycosylphosphatidylinositol-anchored monomeric GFP homo-association disappeared, accompanied by an increase in the expression of the small heat shock protein Hsp27.
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Affiliation(s)
- Mario Brameshuber
- From the Biophysics Institute, Johannes Kepler University Linz, Altenbergerstrasse 69, A-4040 Linz, Austria
| | - Julian Weghuber
- From the Biophysics Institute, Johannes Kepler University Linz, Altenbergerstrasse 69, A-4040 Linz, Austria
| | - Verena Ruprecht
- From the Biophysics Institute, Johannes Kepler University Linz, Altenbergerstrasse 69, A-4040 Linz, Austria
| | - Imre Gombos
- the Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, Hungary, and
| | - Ibolya Horváth
- the Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, Hungary, and
| | - László Vigh
- the Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, Hungary, and
| | - Paul Eckerstorfer
- the Department of Molecular Immunology, Center for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Endre Kiss
- the Department of Molecular Immunology, Center for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Hannes Stockinger
- the Department of Molecular Immunology, Center for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Gerhard J. Schütz
- From the Biophysics Institute, Johannes Kepler University Linz, Altenbergerstrasse 69, A-4040 Linz, Austria
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Plochberger B, Stockner T, Chiantia S, Brameshuber M, Weghuber J, Hermetter A, Schwille P, Schütz GJ. Cholesterol slows down the lateral mobility of an oxidized phospholipid in a supported lipid bilayer. Langmuir 2010; 26:17322-9. [PMID: 20942393 PMCID: PMC2977985 DOI: 10.1021/la1026202] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 09/26/2010] [Indexed: 05/24/2023]
Abstract
We investigated the mobility and phase-partitioning of the fluorescent oxidized phospholipid analogue 1-palmitoyl-2-glutaroyl-sn-glycero-3-phospho-N-Alexa647-ethanolamine (PGPE-Alexa647) in supported lipid bilayers. Compared to the conventional phospholipid dihexadecanoylphosphoethanolamine (DHPE)-Bodipy we found consistently higher diffusion constants. The effect became dramatic when immobile obstacles were inserted into the bilayer, which essentially blocked the diffusion of DHPE-Bodipy but hardly influenced the movements of PGPE-Alexa647. In a supported lipid bilayer made of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), the differences in probe mobility leveled off with increasing cholesterol content. Using coarse-grained molecular dynamics simulations, we could ascribe this effect to increased interactions between the oxidized phospholipid and the membrane matrix, concomitant with a translation in the headgroup position of the oxidized phospholipid: at zero cholesterol content, its headgroup is shifted to the outside of the DOPC headgroup region, whereas increasing cholesterol concentrations pulls the headgroup into the bilayer plane.
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Affiliation(s)
- Birgit Plochberger
- Biophysics Institute, Johannes Kepler University Linz, A-4040 Linz, Austria
| | - Thomas Stockner
- Bioresources, Austrian Institute of Technology, Seibersdorf, A-2444, Austria
- Department of Medical Chemistry, Medical University of Vienna, A-1090 Vienna, Austria
| | - Salvatore Chiantia
- Technical University of Dresden, Biotechnologisches Zentrum, Dresden, Germany
| | - Mario Brameshuber
- Biophysics Institute, Johannes Kepler University Linz, A-4040 Linz, Austria
| | - Julian Weghuber
- Biophysics Institute, Johannes Kepler University Linz, A-4040 Linz, Austria
| | - Albin Hermetter
- Institute of Biochemistry, Graz University of Technology, A-8010 Graz, Austria
| | - Petra Schwille
- Technical University of Dresden, Biotechnologisches Zentrum, Dresden, Germany
| | - Gerhard J. Schütz
- Biophysics Institute, Johannes Kepler University Linz, A-4040 Linz, Austria
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Weghuber J, Brameshuber M, Sunzenauer S, Lehner M, Paar C, Haselgrübler T, Schwarzenbacher M, Kaltenbrunner M, Hesch C, Paster W, Heise B, Sonnleitner A, Stockinger H, Schütz GJ. Detection of protein-protein interactions in the live cell plasma membrane by quantifying prey redistribution upon bait micropatterning. Methods Enzymol 2010; 472:133-51. [PMID: 20580963 DOI: 10.1016/s0076-6879(10)72012-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Our understanding of complex biological systems is based on high-quality proteomics tools for the parallelized detection and quantification of protein interactions. Current screening platforms, however, rely on measuring protein interactions in rather artificial systems, rendering the results difficult to confer on the in vivo situation. We describe here a detailed protocol for the design and the construction of a system to detect and quantify interactions between a fluorophore-labeled protein ("prey") and a membrane protein ("bait") in living cells. Cells are plated on micropatterned surfaces functionalized with antibodies to the bait exoplasmic domain. Bait-prey interactions are assayed via the redistribution of the fluorescent prey. The method is characterized by high sensitivity down to the level of single molecules, the capability to detect weak interactions, and high throughput, making it applicable as a screening tool. The proof-of-concept is demonstrated for the interaction between CD4, a major coreceptor in T-cell signaling, and Lck, a protein tyrosine kinase essential for early T-cell signaling.
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Affiliation(s)
- Julian Weghuber
- Biophysics Institute, Johannes Kepler University Linz, Linz, Austria
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Weghuber J, Sunzenauer S, Plochberger B, Brameshuber M, Haselgrübler T, Schütz GJ. Temporal resolution of protein-protein interactions in the live-cell plasma membrane. Anal Bioanal Chem 2010; 397:3339-47. [PMID: 20574782 PMCID: PMC2911529 DOI: 10.1007/s00216-010-3854-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Accepted: 05/16/2010] [Indexed: 11/20/2022]
Abstract
We have recently devised a method to quantify interactions between a membrane protein ("bait") and a fluorophore-labeled protein ("prey") directly in the live-cell plasma membrane (Schwarzenbacher et al. Nature Methods 5:1053-1060 2008). The idea is to seed cells on surfaces containing micro-patterned antibodies against the exoplasmic domain of the bait, and monitor the co-patterning of the fluorescent prey via fluorescence microscopy. Here, we characterized the time course of bait and prey micropattern formation upon seeding the cells onto the micro-biochip. Patterns were formed immediately after contact of the cells with the surface. Cells were able to migrate over the chip surface without affecting the micropattern contrast, which remained constant over hours. On single cells, bait contrast may be subject to fluctuations, indicating that the bait can be released from and recaptured on the micropatterns. We conclude that interaction studies can be performed at any time-point ranging from 5 min to several hours post seeding. Monitoring interactions with time opens up the possibility for new assays, which are briefly sketched in the discussion section.
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Affiliation(s)
- Julian Weghuber
- Biophysics Institute, Johannes Kepler University Linz, Altenbergerstr.69, 4040 Linz, Austria
| | - Stefan Sunzenauer
- Biophysics Institute, Johannes Kepler University Linz, Altenbergerstr.69, 4040 Linz, Austria
| | - Birgit Plochberger
- Biophysics Institute, Johannes Kepler University Linz, Altenbergerstr.69, 4040 Linz, Austria
| | - Mario Brameshuber
- Biophysics Institute, Johannes Kepler University Linz, Altenbergerstr.69, 4040 Linz, Austria
| | - Thomas Haselgrübler
- Biophysics Institute, Johannes Kepler University Linz, Altenbergerstr.69, 4040 Linz, Austria
| | - Gerhard J. Schütz
- Biophysics Institute, Johannes Kepler University Linz, Altenbergerstr.69, 4040 Linz, Austria
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Huppa JB, Axmann M, Mörtelmaier MA, Lillemeier BF, Newell EW, Brameshuber M, Klein LO, Schütz GJ, Davis MM. TCR-peptide-MHC interactions in situ show accelerated kinetics and increased affinity. Nature 2010; 463:963-7. [PMID: 20164930 DOI: 10.1038/nature08746] [Citation(s) in RCA: 367] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Accepted: 12/07/2009] [Indexed: 11/09/2022]
Abstract
The recognition of foreign antigens by T lymphocytes is essential to most adaptive immune responses. It is driven by specific T-cell antigen receptors (TCRs) binding to antigenic peptide-major histocompatibility complex (pMHC) molecules on other cells. If productive, these interactions promote the formation of an immunological synapse. Here we show that synaptic TCR-pMHC binding dynamics differ significantly from TCR-pMHC binding in solution. We used single-molecule microscopy and fluorescence resonance energy transfer (FRET) between fluorescently tagged TCRs and their cognate pMHC ligands to measure the kinetics of TCR-pMHC binding in situ. When compared with solution measurements, the dissociation of this complex was increased significantly (4-12-fold). Disruption of actin polymers reversed this effect, indicating that cytoskeletal dynamics destabilize this interaction directly or indirectly. Nevertheless, TCR affinity for pMHC was significantly elevated as the result of a large (about 100-fold) increase in the association rate, a likely consequence of complementary molecular orientation and clustering. In helper T cells, the CD4 molecule has been proposed to bind cooperatively with the TCR to the same pMHC complex. However, CD4 blockade had no effect on the synaptic TCR affinity, nor did it destabilize TCR-pMHC complexes, indicating that the TCR binds pMHC independently of CD4.
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Affiliation(s)
- Johannes B Huppa
- Department of Microbiology and Immunology, Stanford School of Medicine, California 94305-5323, USA
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Weghuber J, Sunzenauer S, Brameshuber M, Plochberger B, Hesch C, Schutz GJ. in-vivo detection of protein-protein interactions on micro-patterned surfaces. J Vis Exp 2010:1969. [PMID: 20305612 PMCID: PMC3149983 DOI: 10.3791/1969] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Unraveling the interaction network of molecules in-vivo is key to understanding the mechanisms that regulate cell function and metabolism. A multitude of methodological options for addressing molecular interactions in cells have been developed, but most of these methods suffer from being rather indirect and therefore hardly quantitative. On the contrary, a few high-end quantitative approaches were introduced, which however are difficult to extend to high throughput. To combine high throughput capabilities with the possibility to extract quantitative information, we recently developed a new concept for identifying protein-protein interactions (Schwarzenbacher et al., 2008). Here, we describe a detailed protocol for the design and the construction of this system which allows for analyzing interactions between a fluorophore-labeled protein ("prey") and a membrane protein ("bait") in-vivo. Cells are plated on micropatterned surfaces functionalized with antibodies against the bait exoplasmic domain. Bait-prey interactions are assayed via the redistribution of the fluorescent prey. The method is characterized by high sensitivity down to the level of single molecules, the capability to detect weak interactions, and high throughput capability, making it applicable as screening tool.
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Brameshuber M, Weghuber J, Ruprecht V, Gombos I, Horváth I, Vigh L, Stockinger H, Schuetz GJ. Imaging of Mobile Stable Lipid Rafts in the Live Cell Plasma Membrane and their Involvement in Cellular Signaling During Heat Shock. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.2305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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46
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Weghuber J, Sunzenauer S, Brameshuber M, Wieser S, Rajendran L, Schuetz GJ. Micropatterning of Plasma Membrane Proteins to Analyze Raft Localization in Living Cells. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.2303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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47
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Brameshuber M, Schwarzenbacher M, Kaltenbrunner M, Hesch C, Paster W, Weghuber J, Heise B, Sonnleitner A, Stockinger H, Schütz GJ. Reply to “Uncoupling diffusion and binding in FRAP experiments”. Nat Methods 2009. [DOI: 10.1038/nmeth0309-183b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Brameshuber M, Weghuber J, Stockinger H, Schuetz G. Direct Observation Of Plasma Membrane Rafts Via Live Cell Single Molecule Microscopy. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.1953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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49
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Rhode S, Grurl R, Brameshuber M, Hermetter A, Schütz GJ. Plasma membrane fluidity affects transient immobilization of oxidized phospholipids in endocytotic sites for subsequent uptake. J Biol Chem 2008; 284:2258-65. [PMID: 19043088 DOI: 10.1074/jbc.m807591200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Oxidized phospholipids in serum initiate severe pathophysiological responses during the process of atherogenesis. On the cellular level it is known that these lipids induce apoptosis; however, the uptake mechanism remains enigmatic. We investigated here the behavior of the fluorescent oxidized phospholipid 1-palmitoyl-2-glutaroyl-sn-glycero-3-phospho-N-Alexa647-ethanolamine (PGPE-Alexa647) in the plasma membrane of various cell lines. The probe was taken up by the cells unspecifically via caveolae or clathrin-coated pits. Interestingly, we found the uptake to be facilitated by the overexpression of the scavenger receptor class B type I. Ultra-sensitive microscopy allowed us to follow the uptake process at the single molecule level; we observed rapid diffusion of PGPE-Alexa647 in the plasma membrane, interrupted by transient halts with duration of approximately 0.9 s at endocytotic sites. Scavenger receptor class B type I overexpression yielded a pronounced increase in the single molecule mobility, and in consequence an increased frequency of immobilization. Alternatively, the plasma membrane fluidity could also be increased by treating cells with high levels of the unlabeled oxidized phospholipid 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphocholine; also in this case, the immobilization frequency of PGPE-Alexa647 was concomitantly increased. The data demonstrate the relevance of plasma membrane properties for uptake of oxidized phospholipids, and indicate a novel indirect mechanism for the control of endocytosis.
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Affiliation(s)
- Sebastian Rhode
- Biophysics Institute, Johannes Kepler University Linz, Altenbergerstrasse 69, A-4040 Linz, Austria
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