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Lee H, Choi SQ. Sphingomyelinase-Mediated Multitimescale Clustering of Ganglioside GM1 in Heterogeneous Lipid Membranes. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2101766. [PMID: 34473415 PMCID: PMC8529493 DOI: 10.1002/advs.202101766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 07/19/2021] [Indexed: 05/05/2023]
Abstract
Several signaling processes in the plasma membrane are intensified by ceramides that are formed by sphingomyelinase-mediated hydrolysis of sphingomyelin. These ceramides trigger clustering of signaling-related biomolecules, but how they concentrate such biomolecules remains unclear. Here, the spatiotemporal localization of ganglioside GM1, a glycolipid receptor involved in signaling, during sphingomyelinase-mediated hydrolysis is described. Real-time visualization of the dynamic remodeling of the heterogeneous lipid membrane that occurs due to sphingomyelinase action is used to examine GM1 clustering, and unexpectedly, it is found that it is more complex than previously thought. Specifically, lipid membranes generate two distinct types of condensed GM1: 1) rapidly formed but short-lived GM1 clusters that are formed in ceramide-rich domains nucleated from the liquid-disordered phase; and 2) late-onset yet long-lasting, high-density GM1 clusters that are formed in the liquid-ordered phase. These findings suggest that multiple pathways exist in a plasma membrane to synergistically facilitate the rapid amplification and persistence of signals.
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Affiliation(s)
- Hyun‐Ro Lee
- Department of Chemical and Biomolecular EngineeringKorea Advanced Institute of Science and Technology (KAIST)Daejeon34141Republic of Korea
| | - Siyoung Q. Choi
- Department of Chemical and Biomolecular EngineeringKorea Advanced Institute of Science and Technology (KAIST)Daejeon34141Republic of Korea
- KAIST Institute for the NanoCenturyKorea Advanced Institute of Science and Technology (KAIST)Daejeon34141Republic of Korea
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Lee HR, Lee Y, Oh SS, Choi SQ. Ultra-Stable Freestanding Lipid Membrane Array: Direct Visualization of Dynamic Membrane Remodeling with Cholesterol Transport and Enzymatic Reactions. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2002541. [PMID: 32924281 DOI: 10.1002/smll.202002541] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 07/09/2020] [Indexed: 06/11/2023]
Abstract
Cell membranes actively change their local compositions, serving essential biological processes such as cellular signaling and endocytosis. Although membrane dynamics is vital in the cellular functions, the complexity of natural membranes has made its fundamental understanding and systematic assessment difficult. Here, a powerful artificial membrane system is developed for real-time visualization of the spatiotemporal dynamics of membrane remodeling. Through well-defined air/oil/water interfaces on grid holes, tens of planar lipid bilayer membranes are easily created, and their reproducibility, controllability, and generality are highlighted. The freestanding membranes are large but also highly stable, facilitating direct long-term monitoring of dynamic membrane reconstitution caused by external stimuli. As an example to demonstrate the superiority of this membrane system, the effect of cholesterol trafficking, which significantly affects biophysical properties of cell membranes, is investigated at different membrane compositions. Cholesterol transport into and out of the membranes at different rates causes anomalous lipid arrangements through cholesterol-mediated phase transitions and decomposition, which have never been witnessed before. Furthermore, enzyme-induced membrane dynamics is successfully shown in this platform; sphingomyelinases locally generate asymmetry between two membrane leaflets. This technique is broadly applicable for exploring the membrane heterogeneity under various membrane-based reactions, providing valuable insight into the membrane dynamics.
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Affiliation(s)
- Hyun-Ro Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Yohan Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Seung Soo Oh
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Siyoung Q Choi
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
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Redondo-Morata L, Losada-Pérez P, Giannotti MI. Lipid bilayers: Phase behavior and nanomechanics. CURRENT TOPICS IN MEMBRANES 2020; 86:1-55. [PMID: 33837691 DOI: 10.1016/bs.ctm.2020.08.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Lipid membranes are involved in many physiological processes like recognition, signaling, fusion or remodeling of the cell membrane or some of its internal compartments. Within the cell, they are the ultimate barrier, while maintaining the fluidity or flexibility required for a myriad of processes, including membrane protein assembly. The physical properties of in vitro model membranes as model cell membranes have been extensively studied with a variety of techniques, from classical thermodynamics to advanced modern microscopies. Here we review the nanomechanics of solid-supported lipid membranes with a focus in their phase behavior. Relevant information obtained by quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM) as complementary techniques in the nano/mesoscale interface is presented. Membrane morphological and mechanical characterization will be discussed in the framework of its phase behavior, phase transitions and coexistence, in simple and complex models, and upon the presence of cholesterol.
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Affiliation(s)
- Lorena Redondo-Morata
- Center for Infection and Immunity of Lille, INSERM U1019, CNRS UMR 8204, Lille, France
| | - Patricia Losada-Pérez
- Experimental Soft Matter and Thermal Physics (EST) Group, Department of Physics, Université Libre de Bruxelles, Brussels, Belgium
| | - Marina Inés Giannotti
- Biomedical Research Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid, Spain; Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain; Departament de Ciència de Materials i Química Física, Universitat de Barcelona, Barcelona, Spain.
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Ceramide Domains in Health and Disease: A Biophysical Perspective. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1159:79-108. [DOI: 10.1007/978-3-030-21162-2_6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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5
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Mantil E, Crippin T, Avis TJ. Supported lipid bilayers using extracted microbial lipids: domain redistribution in the presence of fengycin. Colloids Surf B Biointerfaces 2019; 178:94-102. [DOI: 10.1016/j.colsurfb.2019.02.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 02/17/2019] [Accepted: 02/24/2019] [Indexed: 10/27/2022]
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6
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Action of Vipoxin and its separated components on monomolecular film of Dilauroylphosphatidylcholine at the air/water interface. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2018.11.040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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7
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Lamprecht C, Gehrmann M, Madl J, Römer W, Multhoff G, Ebner A. Molecular AFM imaging of Hsp70-1A association with dipalmitoyl phosphatidylserine reveals membrane blebbing in the presence of cholesterol. Cell Stress Chaperones 2018; 23:673-683. [PMID: 29404895 PMCID: PMC6045550 DOI: 10.1007/s12192-018-0879-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 01/10/2018] [Accepted: 01/23/2018] [Indexed: 12/13/2022] Open
Abstract
Hsp70-1A-the major stress-inducible member of the HSP70 chaperone family-is being implicated in cancer diseases with the development of resistances to standard therapies. In normal cells, the protein is purely cytosolic, but in a growing number of tumor cells, a significant fraction can be identified on to the cell surface. The anchoring mechanism is still under debate, as Hsp70-1A lacks conventional signaling sequences for translocation from the cytosol to exoplasmic leaflet of the plasma membrane and common membrane binding domains. Recent reports propose a lipid-mediated anchoring mechanism based on a specific interaction with charged, saturated lipids such as dipalmitoyl phosphatidylserine (DPPS). Here, we prepared planar supported lipid bilayers (SLBs) to visualize the association of Hsp70-1A directly and on the single molecule level by atomic force microscopy (AFM). The single molecule sensitivity of our approach allowed us to explore the low concentration range of 0.05 to 1.0 μg/ml of Hsp70-1A which was not studied before. We compared the binding of the protein to bilayers with 20% DPPS lipid content both in the absence and presence of cholesterol. Hsp70-1A inserted exclusively into DPPS domains and assembled in clusters with increasing protein density. A critical density was reached for incubation with 0.5 μg/ml (7 nM); at higher concentrations, membrane defects were observed that originated from cluster centers. In the presence of cholesterol, this critical concentration leads to the formation of membrane blebs, which burst at higher concentrations supporting a previously proposed non-classical pathway for the export of Hsp70-1A by tumor cells. In the discussion of our data, we attempt to link the lipid-mediated plasma membrane localization of Hsp70-1A to its potential involvement in the development of resistances to radiation and chemotherapy based on our own findings and the current literature.
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Affiliation(s)
- Constanze Lamprecht
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria.
- Institute of Physics, Experimental Polymer Physics, Albert-Ludwigs-University Freiburg, Hermann-Herder-Str. 3, 79104, Freiburg, Germany.
- Freiburg Center for Interactive Materials and Bioinspired Technology (FIT), Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 105, 79110, Freiburg, Germany.
| | - Mathias Gehrmann
- Department of Radiotherapy and Radiooncology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, Munich, Germany
| | - Josef Madl
- Freiburg Center for Interactive Materials and Bioinspired Technology (FIT), Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 105, 79110, Freiburg, Germany
- Faculty of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104, Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs-University Freiburg, Schänzlestraße 18, 79104, Freiburg, Germany
| | - Winfried Römer
- Freiburg Center for Interactive Materials and Bioinspired Technology (FIT), Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 105, 79110, Freiburg, Germany
- Faculty of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104, Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs-University Freiburg, Schänzlestraße 18, 79104, Freiburg, Germany
| | - Gabriele Multhoff
- Department of Radiotherapy and Radiooncology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, Munich, Germany
| | - Andreas Ebner
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
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8
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Burgert A, Schlegel J, Bécam J, Doose S, Bieberich E, Schubert-Unkmeir A, Sauer M. Characterization of Plasma Membrane Ceramides by Super-Resolution Microscopy. Angew Chem Int Ed Engl 2017; 56:6131-6135. [PMID: 28379629 DOI: 10.1002/anie.201700570] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Indexed: 01/04/2023]
Abstract
The sphingolipid ceramide regulates cellular processes such as differentiation, proliferation, growth arrest, and apoptosis. Ceramide-rich membrane areas promote structural changes within the plasma membrane that segregate membrane receptors and affect membrane curvature and vesicle formation, fusion, and trafficking. Ceramides were labeled by immunocytochemistry to visualize their distribution on the plasma membrane of different cells with virtually molecular resolution by direct stochastic optical reconstruction microscopy (dSTORM). Super-resolution images show that independent of labeling conditions and cell type 50-60 % of all membrane ceramides are located in ceramide-rich platforms (CRPs) with a size of about 75 nm that are composed of at least about 20 ceramides. Treatment of cells with Bacillus cereus sphingomyelinase (bSMase) increases the overall ceramide concentration in the plasma membrane, the quantity of CRPs, and their size. Simultaneously, the ceramide concentration in CRPs increases approximately twofold.
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Affiliation(s)
- Anne Burgert
- Department of Biotechnology and Biophysics, Julius Maximilian University Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Jan Schlegel
- Department of Biotechnology and Biophysics, Julius Maximilian University Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Jérôme Bécam
- Institute of Hygiene and Microbiology, Julius Maximilian University Würzburg, 97080, Würzburg, Germany
| | - Sören Doose
- Department of Biotechnology and Biophysics, Julius Maximilian University Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Erhard Bieberich
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | | | - Markus Sauer
- Department of Biotechnology and Biophysics, Julius Maximilian University Würzburg, Am Hubland, 97074, Würzburg, Germany
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9
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Burgert A, Schlegel J, Bécam J, Doose S, Bieberich E, Schubert‐Unkmeir A, Sauer M. Characterization of Plasma Membrane Ceramides by Super‐Resolution Microscopy. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201700570] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Anne Burgert
- Department of Biotechnology and Biophysics Julius Maximilian University Würzburg Am Hubland 97074 Würzburg Germany
| | - Jan Schlegel
- Department of Biotechnology and Biophysics Julius Maximilian University Würzburg Am Hubland 97074 Würzburg Germany
| | - Jérôme Bécam
- Institute of Hygiene and Microbiology Julius Maximilian University Würzburg 97080 Würzburg Germany
| | - Sören Doose
- Department of Biotechnology and Biophysics Julius Maximilian University Würzburg Am Hubland 97074 Würzburg Germany
| | - Erhard Bieberich
- Department of Neuroscience and Regenerative Medicine Medical College of Georgia Augusta University Augusta GA 30912 USA
| | | | - Markus Sauer
- Department of Biotechnology and Biophysics Julius Maximilian University Würzburg Am Hubland 97074 Würzburg Germany
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10
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Mantil E, Crippin T, Ianoul A, Avis TJ. Experimental Parameters Leading to Optimal Bilayers for Total Internal Reflection Fluorescence Microscopy Visualization. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2017; 23:97-112. [PMID: 28228172 DOI: 10.1017/s1431927617000083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Supported lipid bilayer systems were evaluated following various experimental procedures in an effort to determine their appropriateness for visualization using total internal reflection fluorescence (TIRF) microscopy. The incorporation and distribution of Texas Red® 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (TR-DHPE) was studied when incorporated into bilayers of variable lipid composition using different forms of mechanical shearing. Results showed that 0.8 mol% TR-DHPE provides the most optimum TIRF images. At this concentration, a sufficient level of photostability can be achieved without an undesirable increase in TR-DHPE aggregates caused by excess probe molecules. Solutions composed of a 3:1 molar ratio of DOPC:DPPC with 0.8 mol% TR-DHPE produce bilayers that consistently display clear, distinct, rounded domains, whereas other lipid compositions did not. This optimum phase separation appears to be influenced by an increase in mechanical shearing during the vesicle formation process, when the lipid solutions were exposed to sonication and extrusion processes. The combination of a sonication and extrusion process also helped with eliminating the presence of TR-DHPE aggregates within the model membranes. It was also shown that bilayers formed on conditioned glass, placed on a slide, produced more highly detailed bilayers in which distinct lipid phase separation could be optimally visualized using TIRF microscopy.
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Affiliation(s)
- Elisabeth Mantil
- 1Department of Chemistry,Carleton University,1125 Colonel By Drive,Ottawa,ON K1S 5B6,Canada
| | - Trinda Crippin
- 2Department of Biology,Carleton University,1125 Colonel By Drive,Ottawa,ON K1S 5B6,Canada
| | - Anatoli Ianoul
- 1Department of Chemistry,Carleton University,1125 Colonel By Drive,Ottawa,ON K1S 5B6,Canada
| | - Tyler J Avis
- 1Department of Chemistry,Carleton University,1125 Colonel By Drive,Ottawa,ON K1S 5B6,Canada
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11
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Hasan IY, Mechler A. Analytical approaches to study domain formation in biomimetic membranes. Analyst 2017; 142:3062-3078. [PMID: 28758651 DOI: 10.1039/c7an01038a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Novel characterization methods open new horizons in the study of membrane mixtures.
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Affiliation(s)
- Imad Younus Hasan
- La Trobe Institute for Molecular Science
- La Trobe University
- Melbourne
- Australia
| | - Adam Mechler
- La Trobe Institute for Molecular Science
- La Trobe University
- Melbourne
- Australia
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12
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Villareal VA, Rodgers MA, Costello DA, Yang PL. Targeting host lipid synthesis and metabolism to inhibit dengue and hepatitis C viruses. Antiviral Res 2015; 124:110-21. [PMID: 26526588 DOI: 10.1016/j.antiviral.2015.10.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 10/08/2015] [Accepted: 10/11/2015] [Indexed: 12/16/2022]
Abstract
Lipids are necessary for every step in the replication cycle of hepatitis C virus (HCV) and dengue virus (DENV), members of the family Flaviviridae. Recent studies have demonstrated that discrete steps in the replication cycles of these viruses can be inhibited by pharmacological agents that target host factors mediating lipid synthesis, metabolism, trafficking, and signal transduction. Despite this, targeting host lipid metabolism and trafficking as an antiviral strategy by blockade of entire pathways may be limited due to host toxicity. Knowledge of the molecular details of lipid structure and function in replication and the mechanisms whereby specific lipids are generated and trafficked to the relevant sites may enable more targeted antiviral strategies without global effects on the host cell. In this review, we discuss lipids demonstrated to be critical to the replication cycles of HCV and DENV and highlight potential areas for anti-viral development. This review article forms part of a symposium on flavivirus drug discovery in Antiviral Research.
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Affiliation(s)
- Valerie A Villareal
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
| | - Mary A Rodgers
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
| | - Deirdre A Costello
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
| | - Priscilla L Yang
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA.
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Ekman P, Maula T, Yamaguchi S, Yamamoto T, Nyholm TK, Katsumura S, Slotte J. Formation of an ordered phase by ceramides and diacylglycerols in a fluid phosphatidylcholine bilayer — Correlation with structure and hydrogen bonding capacity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:2111-7. [DOI: 10.1016/j.bbamem.2015.06.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Revised: 06/18/2015] [Accepted: 06/19/2015] [Indexed: 12/21/2022]
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Castro BM, Prieto M, Silva LC. Ceramide: a simple sphingolipid with unique biophysical properties. Prog Lipid Res 2014; 54:53-67. [PMID: 24513486 DOI: 10.1016/j.plipres.2014.01.004] [Citation(s) in RCA: 260] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 01/29/2014] [Accepted: 01/29/2014] [Indexed: 02/06/2023]
Abstract
Ceramides are involved in a variety of cellular processes and in disease. Their biological functions are thought to depend on ceramides' unique biophysical properties, which promote strong alterations of cell membrane properties and consequent triggering of signaling events. Over the last decades, efforts were made to understand the impact of ceramide on membrane biophysical features. Several studies, performed in a multitude of membrane models, address ceramides' specific interactions, the effect of their acyl chain structure and the influence of membrane lipid composition and properties on ceramide biophysical outcome. In this review, a rationale for the multiple and complex changes promoted by ceramide is provided, highlighting, on a comprehensive and critical manner, the interactions between ceramides and specific lipids and/or lipid phases. Focus is also given to the interplay between ceramide and cholesterol, particularly in lipid raft-mimicking mixtures, an issue of intense debate due to the urgent need to understand the biophysical impact of ceramide formation in models resembling the cell membrane. The implications of ceramide-induced biophysical changes on lipid-protein interactions and cell signaling are also discussed, together with the emerging evidence for the existence of ceramide-gel like domains in cellular membranes.
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Affiliation(s)
- Bruno M Castro
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Complexo I, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Manuel Prieto
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Complexo I, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Liana C Silva
- iMed.UL - Research Institute for Medicines and Pharmaceutical Sciences, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal.
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15
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Alejo JL, Blanchard SC, Andersen OS. Small-molecule photostabilizing agents are modifiers of lipid bilayer properties. Biophys J 2014; 104:2410-8. [PMID: 23746513 DOI: 10.1016/j.bpj.2013.04.039] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 04/09/2013] [Accepted: 04/11/2013] [Indexed: 10/26/2022] Open
Abstract
Small-molecule photostabilizing or protective agents (PAs) provide essential support for the stability demands on fluorescent dyes in single-molecule spectroscopy and fluorescence microscopy. These agents are employed also in studies of cell membranes and model systems mimicking lipid bilayer environments, but there is little information about their possible effects on membrane structure and physical properties. Given the impact of amphipathic small molecules on bilayer properties such as elasticity and intrinsic curvature, we investigated the effects of six commonly used PAs--cyclooctatetraene (COT), para-nitrobenzyl alcohol (NBA), Trolox (TX), 1,4-diazabicyclo[2.2.2]octane (DABCO), para-nitrobenzoic acid (pNBA), and n-propyl gallate (nPG)--on bilayer properties using a gramicidin A (gA)-based fluorescence quench assay to probe for PA-induced changes in the gramicidin monomer↔dimer equilibrium. The experiments were done using fluorophore-loaded large unilamellar vesicles that had been doped with gA, and changes in the gA monomer↔dimer equilibrium were assayed using a gA channel-permeable fluorescence quencher (Tl⁺). Changes in bilayer properties caused by, e.g., PA adsorption at the bilayer/solution interface that alter the equilibrium constant for gA channel formation, and thus the number of conducting gA channels in the large unilamellar vesicle membrane, will be detectable as changes in the rate of Tl⁺ influx-the fluorescence quench rate. Over the experimentally relevant millimolar concentration range, TX, NBA, and pNBA, caused comparable increases in gA channel activity. COT, also in the millimolar range, caused a slight decrease in gA channel activity. nPG increased channel activity at submillimolar concentrations. DABCO did not alter gA activity. Five of the six tested PAs thus alter lipid bilayer properties at experimentally relevant concentrations, which becomes important for the design and analysis of fluorescence studies in cells and model membrane systems. We therefore tested combinations of COT, NBA, and TX; the combinations altered the fluorescence quench rate less than would be predicted assuming their effects on bilayer properties were additive. The combination of equimolar concentrations of COT and NBA caused minimal changes in the fluorescence quench rate.
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Affiliation(s)
- Jose L Alejo
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA
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Ramirez DMC, Jakubek ZJ, Lu Z, Ogilvie WW, Johnston LJ. Changes in order parameters associated with ceramide-mediated membrane reorganization measured using pTIRFM. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:15907-15918. [PMID: 24308875 DOI: 10.1021/la403585v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The enzymatic generation of ceramide has significant effects on the biophysical properties of lipid bilayers and can lead to the extensive reorganization of cell membranes. We have synthesized and characterized a headgroup-labeled fluorescent lipid probe (NBD-ceramide, NBD-Cer) and demonstrated that it can be used for polarized total internal reflection fluorescence microscopy experiments to probe changes in membrane order that result from ceramide incorporation. NBD-Cer measures significantly higher order parameters for the liquid-ordered (Lo) domains ([P2] = 0.40 ± 0.03) than for the liquid-disordered phase (Ld, fluid, [P2] = 0.22 ± 0.02) of phase-separated bilayers prepared from egg sphingomyelin, dioleolyphosphatidylcholine, and cholesterol mixtures. The probe also responds to changes in packing induced by the direct incorporation of ceramide or the variation in the ionic strength of the aqueous medium. Order parameter maps obtained after enzyme treatment of bilayers with coexisting Lo and Ld phases show two distinct types of behavior. In regions of high enzyme activity, the initial Lo/Ld domains are replaced by large, dark features that have high membrane order corroborating previous hypotheses that these are ceramide-enriched regions of the membrane. In areas of low enzyme activity, the size and shape of the Lo domains are conserved, but there is an increase in the order parameter for the initial Ld phase ([P2] = 0.30 ± 0.01). This is attributed to the incorporation of ceramide in the Lo domains with the concomitant expulsion of cholesterol into the surrounding fluid phase, increasing its order parameter.
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Affiliation(s)
- Daniel M Carter Ramirez
- Measurement Science and Standards, National Research Council of Canada , Ottawa, Ontario K1A 0R6, Canada
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Carter Ramirez DM, Kim YA, Bittman R, Johnston LJ. Lipid Phase Separation and Protein-Ganglioside Clustering in Supported Bilayers Are Induced by Photorelease of Ceramide. SOFT MATTER 2013; 9:4890-4899. [PMID: 23667384 PMCID: PMC3649770 DOI: 10.1039/c3sm50240f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Photolysis of 6-bromo-7-hydroxycoumarinyl-caged ceramide was used to generate ceramide with spatial and temporal control in supported lipid bilayers prepared from mixtures of caged ceramide and phospholipids. The caged ceramide molecules are randomly distributed in fluid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayers, and upon photolysis with long wavelength UV light small ordered ceramide domains are formed that phase separate from the bulk fluid membrane. Irradiation of a spatially restricted area leads to the transient formation of ceramide-enriched gel phase domains that equilibrate via lipid diffusion with the surrounding unirradiated membrane. Photorelease of C16-ceramide in supported bilayers prepared from POPC, caged ceramide and the ganglioside GM1 (90:10:1 molar ratio) results in partitioning of a ganglioside-protein complex into the ceramide-enriched domains, modeling some aspects of ceramide's behavior in cells. The photo-uncaging strategy used here for delivery of ceramide in bilayers provides a novel and useful alternative to the enzymatic generation of ceramide in sphingomyelin-containing membranes. The ability to control membrane phase separation behavior and the clustering of membrane-anchored proteins illustrates the potential of photo-uncaging for studying the compartmentalization of ceramide in cellular membranes.
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Affiliation(s)
- Daniel M Carter Ramirez
- Measurement Science and Standards, National Research Council of Canada, Ottawa, ON K1A 0R6, CANADA ; Department of Chemistry, University of Ottawa, Ottawa, ON K1N 6N5, CANADA
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Li JJ, Yip CM. Super-resolved FT-IR spectroscopy: Strategies, challenges, and opportunities for membrane biophysics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2272-82. [PMID: 23500349 DOI: 10.1016/j.bbamem.2013.02.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Accepted: 02/25/2013] [Indexed: 01/16/2023]
Abstract
Direct correlation of molecular conformation with local structure is critical to studies of protein- and peptide-membrane interactions, particularly in the context of membrane-facilitated aggregation, and disruption or disordering. Infrared spectroscopy has long been a mainstay for determining molecular conformation, following folding dynamics, and characterizing reactions. While tremendous advances have been made in improving the spectral and temporal resolution of infrared spectroscopy, it has only been with the introduction of scanned-probe techniques that exploit the raster-scanning tip as either a source, scattering tool, or measurement probe that researchers have been able to obtain sub-diffraction limit IR spectra. This review will examine the history of correlated scanned-probe IR spectroscopies, from their inception to their use in studies of molecular aggregates, membrane domains, and cellular structures. The challenges and opportunities that these platforms present for examining dynamic phenomena will be discussed. This article is part of a Special Issue entitled: FTIR in membrane proteins and peptide studies.
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Affiliation(s)
- Jessica J Li
- Department of Chemical Engineering and Applied Chemistry, Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada M5S 3E1
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Ramirez DMC, Pitre SP, Kim YA, Bittman R, Johnston LJ. Photouncaging of ceramides promotes reorganization of liquid-ordered domains in supported lipid bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:3380-3387. [PMID: 23402522 PMCID: PMC3607952 DOI: 10.1021/la3039158] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
6-Bromo-7-hydroxycoumarin (Bhc)-caged ceramide (Cer) analogs were incorporated into supported lipid bilayers containing a mixture of coexisting liquid-ordered (Lo) and liquid-disordered (Ld) phases. The release of N-palmitoyl and N-butanoyl-D-erythro-sphingosine (C16- and C4-Cer) by the photolysis of caged Cers using long-wavelength UV light was studied using a combination of atomic force microscopy and fluorescence microscopy. This approach demonstrated the ability to generate Cer with spatial and temporal control, providing an alternative method to the enzymatic generation of Cer. The generation of C16-Cer from Bhc-C16-Cer disrupted the Lo domains, with the incorporation of small fluid-phase regions and the disappearance of some smaller domains. Cer-rich gel-phase domains were not observed, in contrast to results reported by either direct Cer incorporation or enzymatic Cer generation. The photorelease of C4-Cer from Bhc-C4-Cer resulted in qualitatively similar changes in bilayer morphology, with the disappearance of some Lo domains and no evidence of Cer-rich gel domains but with a smaller height difference between the ordered and disordered phases.
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20
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Insights into sphingolipid miscibility: separate observation of sphingomyelin and ceramide N-acyl chain melting. Biophys J 2012; 103:2465-74. [PMID: 23260048 DOI: 10.1016/j.bpj.2012.10.041] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 09/27/2012] [Accepted: 10/03/2012] [Indexed: 01/01/2023] Open
Abstract
Ceramide produced from sphingomyelin in the plasma membrane is purported to affect signaling through changes in the membrane's physical properties. Thermal behavior of N-palmitoyl sphingomyelin (PSM) and N-palmitoyl ceramide (PCer) mixtures in excess water has been monitored by ²H NMR spectroscopy and compared to differential scanning calorimetry (DSC) data. The alternate use of either perdeuterated or proton-based N-acyl chain PSM and PCer in our ²H NMR studies has allowed the separate observation of gel-fluid transitions in each lipid in the presence of the other one, and this in turn has provided direct information on the lipids' miscibility over a wide temperature range. The results provide further evidence of the stabilization of the PSM gel state by PCer. Moreover, overlapping NMR and DSC data reveal that the DSC-signals parallel the melting of the major component (PSM) except at intermediate (20 and 30 mol %) fractions of PCer. In such cases, the DSC endotherm reports on the presumably highly cooperative melting of PCer. Up to at least 50 mol % PCer, PSM and PCer mix ideally in the liquid crystalline phase; in the gel phase, PCer becomes incorporated into PSM:PCer membranes with no evidence of pure solid PCer.
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21
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Ale EC, Maggio B, Fanani ML. Ordered-disordered domain coexistence in ternary lipid monolayers activates sphingomyelinase by clearing ceramide from the active phase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2767-76. [DOI: 10.1016/j.bbamem.2012.06.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 05/01/2012] [Accepted: 06/25/2012] [Indexed: 01/02/2023]
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22
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Morandat S, Azouzi S, Beauvais E, Mastouri A, El Kirat K. Atomic force microscopy of model lipid membranes. Anal Bioanal Chem 2012; 405:1445-61. [DOI: 10.1007/s00216-012-6383-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2012] [Revised: 08/02/2012] [Accepted: 08/24/2012] [Indexed: 10/27/2022]
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In situ synthesis of fluorescent membrane lipids (ceramides) using click chemistry. J Chem Biol 2012; 5:119-23. [PMID: 23596500 DOI: 10.1007/s12154-012-0075-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 04/03/2012] [Indexed: 01/08/2023] Open
Abstract
Ceramide analogues containing azide groups either in the polar head or in the hydrocarbon chains are non-fluorescent. When incorporated into phospholipid bilayers, they can react in situ with a non-fluorescent 1,8-naphthalimide using click chemistry giving rise to fluorescent ceramide derivatives emitting at ≈440 nm. When incorporated into giant unilamellar vesicles, two-photon excitation at 760 nm allows visualization of the ceramide-containing bilayers. This kind of method may be of general applicability in the study of model and cell membranes.
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Mulligan K, Jakubek ZJ, Johnston LJ. Supported lipid bilayers on biocompatible polysaccharide multilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:14352-14359. [PMID: 22013993 DOI: 10.1021/la203207p] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Formation of supported lipid bilayers on soft polymer cushions is a useful approach to decouple the membrane from the substrate for applications involving membrane proteins. We prepared biocompatible polymer cushions by the layer-by-layer assembly of two polysaccharide polyelectrolytes, chitosan (CHI) and hyaluronic acid, on glass and silicon substrates. (CHI/HA)(5) films were characterized by atomic force microscopy, giving an average thickness of 57 nm and roughness of 25 nm in aqueous solution at pH 6.5. Formation of zwitterionic lipid bilayers by the vesicle fusion method was attempted using DOPC vesicles at pH 4 and 6.5 on (CHI/HA)(5) films. At higher pH adsorbed lipids had low mobility and large immobile lipid fractions; a combination of fluorescence and AFM indicated that this was attributable to formation of poor quality membranes with defects and pinned lipids rather than to a layer of surface-adsorbed vesicles. By contrast, more uniform bilayers with mobile lipids were produced at pH 4. Fluorescence recovery after photobleaching gave diffusion coefficients that were similar to those for bilayers on PEG cushions and considerably higher than those measured on other polyelectrolyte films. The results suggest that the polymer surface charge is more important than the surface roughness in controlling formation of mobile supported bilayers. These results demonstrate that polysaccharides provide a useful alternative to other polymer cushions, particularly for applications where biocompatibility is important.
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Affiliation(s)
- Kirk Mulligan
- Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6
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25
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Abstract
Biological research has always tremendously benefited from the development of key methodology. In fact, it was the advent of microscopy that shaped our understanding of cells as the fundamental units of life. Microscopic techniques are still central to the elucidation of biological units and processes, but equally important are methods that allow access to the dimension of time, to investigate the dynamics of molecular functions and interactions. Here, fluorescence spectroscopy with its sensitivity to access the single-molecule level, and its large temporal resolution, has been opening up fully new perspectives for cell biology. Here we summarize the key fluorescent techniques used to study cellular dynamics, with the focus on lipid and membrane systems.
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Carter Ramirez DM, Ding J, Guan J, Vobornik D, Carnini A, Ogilvie WW, Jakubek ZJ, Johnston LJ. A Förster resonance energy transfer (FRET) approach for enhancing fluorescence contrast in phase-separated membranes. CAN J CHEM 2011. [DOI: 10.1139/v10-144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The partitioning of the dye-labeled lipid probe, NBD-DHPE (1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-(7-nitro-2-1,3-benzoxadiazol-4-yl) (ammonium salt)), was examined by fluorescence microscopy in phase-separated lipid bilayers with mixtures of coexisting liquid-ordered and fluid phases. This probe shows slightly higher fluorescence intensity in the ordered domains but undergoes a contrast reversal to give a more strongly fluorescent fluid phase in the presence of >0.2% Texas red-DHPE (TR-DHPE). The change in contrast is shown to result from Förster resonance energy transfer between the NBD donor and TR acceptor in the fluid phase, which has a TR concentration that is approximately 3 times higher than in the domains. An alternate approach using a nitroxide-substituted lipid that partitions into the fluid phase as a quencher, was also examined as a means to enhance the contrast; however, the quencher modified the behaviour of the bilayer. The energy transfer method for enhancing the contrast between ordered and fluid phases was used to examine the morphology of enzyme-treated bilayers.
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Affiliation(s)
- Daniel M. Carter Ramirez
- Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, K1A 0R6 ON, Canada
- Department of Chemistry, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Jason Ding
- Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, K1A 0R6 ON, Canada
- Department of Chemistry, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Jack Guan
- Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, K1A 0R6 ON, Canada
- Department of Chemistry, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Dusan Vobornik
- Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, K1A 0R6 ON, Canada
- Department of Chemistry, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Anna Carnini
- Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, K1A 0R6 ON, Canada
- Department of Chemistry, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - William W. Ogilvie
- Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, K1A 0R6 ON, Canada
- Department of Chemistry, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Zygmunt J. Jakubek
- Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, K1A 0R6 ON, Canada
- Department of Chemistry, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Linda J. Johnston
- Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, K1A 0R6 ON, Canada
- Department of Chemistry, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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Abstract
The atomic force microscope (AFM) is a high-resolution scanning-probe instrument which has become an important tool for cellular and molecular biophysics in recent years, but lacks the time resolution and functional specificities offered by fluorescence microscopic techniques. The advantages of both methods may be exploited by combining and synchronizing them. In this paper, the biological applications of AFM, fluorescence, and their combinations are briefly reviewed, and the assembly and utilization of a spatially and temporally synchronized AFM and total internal reflection fluorescence microscope are described. The application of the method is demonstrated on a fluorescently labeled cell culture.
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Affiliation(s)
- Miklós S Z Kellermayer
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary.
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Sullan RMA, Li JK, Hao C, Walker GC, Zou S. Cholesterol-dependent nanomechanical stability of phase-segregated multicomponent lipid bilayers. Biophys J 2010; 99:507-16. [PMID: 20643069 DOI: 10.1016/j.bpj.2010.04.044] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 04/15/2010] [Accepted: 04/19/2010] [Indexed: 11/19/2022] Open
Abstract
Cholesterol is involved in endocytosis, exocytosis, and the assembly of sphingolipid/cholesterol-enriched domains, as has been demonstrated in both model membranes and living cells. In this work, we explored the influence of different cholesterol levels (5-40 mol%) on the morphology and nanomechanical stability of phase-segregated lipid bilayers consisting of dioleoylphosphatidylcholine/sphingomyelin/cholesterol (DOPC/SM/Chol) by means of atomic force microscopy (AFM) imaging and force mapping. Breakthrough forces were consistently higher in the SM/Chol-enriched liquid-ordered domains (Lo) than in the DOPC-enriched fluid-disordered phase (Ld) at a series of loading rates. We also report the activation energies (DeltaEa) for the formation of an AFM-tip-induced fracture, calculated by a model for the rupture of molecular thin films. The obtained DeltaEa values agree remarkably well with reported values for fusion-related processes using other techniques. Furthermore, we observed that within the Chol range studied, the lateral organization of bilayers can be categorized into three distinct groups. The results are rationalized by fracture nanomechanics of a ternary phospholipid/sphingolipid/cholesterol mixture using correlated AFM-based imaging and force mapping, which demonstrates the influence of a wide range of cholesterol content on the morphology and nanomechanical stability of model bilayers. This provides fundamental insights into the role of cholesterol in the formation and stability of sphingolipid/cholesterol-enriched domains, as well as in membrane fusion.
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Affiliation(s)
- Ruby May A Sullan
- Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, Ontario, Canada
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30
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Fanani ML, Hartel S, Maggio B, De Tullio L, Jara J, Olmos F, Oliveira RG. The action of sphingomyelinase in lipid monolayers as revealed by microscopic image analysis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1309-23. [DOI: 10.1016/j.bbamem.2010.01.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Revised: 12/16/2009] [Accepted: 01/04/2010] [Indexed: 11/26/2022]
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Rotstein NP, Miranda GE, Abrahan CE, German OL. Regulating survival and development in the retina: key roles for simple sphingolipids. J Lipid Res 2010; 51:1247-62. [PMID: 20100817 PMCID: PMC3035489 DOI: 10.1194/jlr.r003442] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Revised: 01/25/2010] [Indexed: 12/28/2022] Open
Abstract
Many sphingolipids have key functions in the regulation of crucial cellular processes. Ceramide (Cer) and sphingosine (Sph) induce growth arrest and cell death in multiple situations of cellular stress. On the contrary, sphingosine-1-phosphate (S1P), the product of Sph phosphorylation, promotes proliferation, differentiation, and survival in different cell systems. This review summarizes the roles of these simple sphingolipids in different tissues and then analyzes their possible functions in the retina. Alterations in proliferation, neovascularization, differentiation, and cell death are critical in major retina diseases and collective evidence points to a role for sphingolipids in these processes. Cer induces inflammation and apoptosis in endothelial and retinal pigmented epithelium cells, leading to several retinopathies. S1P can prevent this death but also promotes cell proliferation that might lead to neovascularization and fibrosis. Recent data support Cer and Sph as crucial mediators in the induction of photoreceptor apoptosis in diverse models of oxidative damage and neurodegeneration, and suggest that regulating their metabolism can prevent this death. New evidence proposes a central role for S1P controlling photoreceptor survival and differentiation. Finally, this review discusses the ability of trophic factors to regulate sphingolipid metabolism and transactivate S1P signaling pathways to control survival and development in retina photoreceptors.
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Affiliation(s)
- Nora P Rotstein
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur-CONICET, Bahía Blanca, Buenos Aires, Argentina.
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Sterol affinity for bilayer membranes is affected by their ceramide content and the ceramide chain length. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1008-13. [DOI: 10.1016/j.bbamem.2009.12.025] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 12/22/2009] [Accepted: 12/24/2009] [Indexed: 12/16/2022]
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33
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Surface analysis of membrane dynamics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:766-76. [DOI: 10.1016/j.bbamem.2009.09.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Revised: 09/18/2009] [Accepted: 09/20/2009] [Indexed: 11/18/2022]
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34
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El Kirat K, Morandat S, Dufrêne YF. Nanoscale analysis of supported lipid bilayers using atomic force microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:750-65. [DOI: 10.1016/j.bbamem.2009.07.026] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 07/17/2009] [Accepted: 07/23/2009] [Indexed: 12/11/2022]
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35
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Ramirez DMC, Ogilvie WW, Johnston LJ. NBD-cholesterol probes to track cholesterol distribution in model membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:558-68. [DOI: 10.1016/j.bbamem.2009.12.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Revised: 11/17/2009] [Accepted: 12/08/2009] [Indexed: 01/08/2023]
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36
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Stancevic B, Kolesnick R. Ceramide-rich platforms in transmembrane signaling. FEBS Lett 2010; 584:1728-40. [PMID: 20178791 DOI: 10.1016/j.febslet.2010.02.026] [Citation(s) in RCA: 209] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Revised: 02/10/2010] [Accepted: 02/10/2010] [Indexed: 01/08/2023]
Abstract
Recent evidence suggests that ceramide regulates stress signaling via reorganization of the plasma membrane. The focus of this review will be to discuss the mechanism by which acid sphingomyelinase (ASMase)-generated ceramide initiates transmembrane signaling in the plasma membrane exoplasmic leaflet. In particular, we review the unique biophysical properties of ceramide that render it proficient in formation of signaling domains termed ceramide-rich platforms (CRPs), and the role of CRPs in the pathophysiology of various diseases. The biomedical significance of CRPs makes these structures an attractive therapeutic target.
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Affiliation(s)
- Branka Stancevic
- Laboratory of Signal Transduction, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
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37
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Sullan RMA, Li JK, Zou S. Quantification of the nanomechanical stability of ceramide-enriched domains. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:12874-12877. [PMID: 19835362 DOI: 10.1021/la903442s] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The quantification of the mechanical stability of lipid bilayers is important in establishing composition-structure-property relations and sheds light on our understanding of the functions of biological membranes. Here, we designed an experiment to directly probe and quantify the nanomechanical stability and rigidity of the ceramide-enriched platforms that play a distinctive role in a variety of cellular processes. Our force mapping results have demonstrated that the ceramide-enriched domains require both methyl beta-cyclodextrin (MbCD) and chloroform treatments to weaken their highly ordered organization, suggesting a lipid packing that is different from that in typical gel states. Our results also show the expulsion of cholesterol from the sphingolipid/cholesterol-enriched domains as a result of ceramide incorporation. This work provides quantitative information on the nanomechanical stability and rigidity of coexisting phase-segregated lipid bilayers with the presence of ceramide-enriched platforms, indicating that that generation of ceramide in cells drastically alters the structural organization and the mechanical property of biological membranes.
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Affiliation(s)
- Ruby May A Sullan
- Steacie Institute for Molecular Sciences, National Research Council Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada
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Ceramide acyl chain length markedly influences miscibility with palmitoyl sphingomyelin in bilayer membranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 39:1117-28. [DOI: 10.1007/s00249-009-0562-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 10/21/2009] [Accepted: 10/26/2009] [Indexed: 10/20/2022]
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