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Gajate C, Mollinedo F. Lipid Raft Isolation by Sucrose Gradient Centrifugation and Visualization of Raft-Located Proteins by Fluorescence Microscopy: The Use of Combined Techniques to Assess Fas/CD95 Location in Rafts During Apoptosis Triggering. Methods Mol Biol 2021; 2187:147-186. [PMID: 32770506 DOI: 10.1007/978-1-0716-0814-2_9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Lipid rafts are heterogeneous membrane domains enriched in cholesterol, sphingolipids, and gangliosides that serve as sorting platforms to compartmentalize and modulate signaling pathways. Death receptors and downstream signaling molecules have been reported to be recruited into these raft domains during the triggering of apoptosis. Here, we provide two protocols that support the presence of Fas/CD95 in lipid rafts during apoptosis, involving lipid raft isolation and confocal microscopy techniques. A detailed protocol is provided for the isolation of lipid rafts, by taking advantage of their resistance to Triton X-100 solubilization at 4 °C, followed by subsequent sucrose gradient centrifugation and analysis of the protein composition of the different gradient fractions by Western blotting. In addition, we also provide a detailed protocol for the visualization of the coclustering of Fas/CD95 death receptor and lipid rafts, as assessed by using anti-Fas/CD95 antibodies and fluorescent dye-conjugated cholera toxin B subunit that binds to ganglioside GM1, a main component of lipid rafts, by immunofluorescence and confocal microscopy. These protocols can be extended to any protein of interest to be analyzed for its association to lipid rafts.
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Affiliation(s)
- Consuelo Gajate
- Laboratory of Cell Death and Cancer Therapy, Department of Molecular Biomedicine, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Faustino Mollinedo
- Laboratory of Cell Death and Cancer Therapy, Department of Molecular Biomedicine, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain.
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2
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Riske KA, Domingues CC, Casadei BR, Mattei B, Caritá AC, Lira RB, Preté PSC, de Paula E. Biophysical approaches in the study of biomembrane solubilization: quantitative assessment and the role of lateral inhomogeneity. Biophys Rev 2017; 9:649-667. [PMID: 28836235 PMCID: PMC5662047 DOI: 10.1007/s12551-017-0310-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 08/01/2017] [Indexed: 10/19/2022] Open
Abstract
Detergents are amphiphilic molecules widely used to solubilize biological membranes and/or extract their components. Nevertheless, because of the complex composition of biomembranes, their solubilization by detergents has not been systematically studied. In this review, we address the solubilization of erythrocytes, which provide a relatively simple, robust and easy to handle biomembrane, and of biomimetic models, to stress the role of the lipid composition on the solubilization process. First, results of a systematic study on the solubilization of human erythrocyte membranes by different series of non-ionic (Triton, CxEy, Brij, Renex, Tween), anionic (bile salts) and zwitterionic (ASB, CHAPS) detergents are shown. Such quantitative approach allowed us to propose Resat-the effective detergent/lipid molar ratio in the membrane for the onset of hemolysis as a new parameter to classify the solubilization efficiency of detergents. Second, detergent-resistant membranes (DRMs) obtained as a result of the partial solubilization of erythrocytes by TX-100, C12E8 and Brij detergents are examined. DRMs were characterized by their cholesterol, sphingolipid and specific proteins content, as well as lipid packing. Finally, lipid bilayers of tuned lipid composition forming liposomes were used to investigate the solubilization process of membranes of different compositions/phases induced by Triton X-100. Optical microscopy of giant unilamellar vesicles revealed that pure phospholipid membranes are fully solubilized, whereas the presence of cholesterol renders the mixture partially or even fully insoluble, depending on the composition. Additionally, Triton X-100 induced phase separation in raft-like mixtures, and selective solubilization of the fluid phase only.
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Affiliation(s)
- Karin A Riske
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, 04039-032, Brazil
| | - Cleyton C Domingues
- Departamento de Bioquímica e Biologia Tecidual, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), P.O. Box - 6109, Campinas, SP, CEP 13083-862, Brazil
- Department of Medicine, School of Medicine & Health Sciences, The George Washington University, Washington, DC, 200037, USA
| | - Bruna R Casadei
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, 04039-032, Brazil
- Departamento de Bioquímica e Biologia Tecidual, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), P.O. Box - 6109, Campinas, SP, CEP 13083-862, Brazil
| | - Bruno Mattei
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, 04039-032, Brazil
| | - Amanda C Caritá
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, 04039-032, Brazil
| | - Rafael B Lira
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, 04039-032, Brazil
| | - Paulo S C Preté
- Departamento de Bioquímica e Biologia Tecidual, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), P.O. Box - 6109, Campinas, SP, CEP 13083-862, Brazil
- Departamento de Química, Universidade Federal de Lavras, Lavras, MG, 37200-000, Brazil
| | - Eneida de Paula
- Departamento de Bioquímica e Biologia Tecidual, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), P.O. Box - 6109, Campinas, SP, CEP 13083-862, Brazil.
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3
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The Myxobacterial Metabolite Soraphen A Inhibits HIV-1 by Reducing Virus Production and Altering Virion Composition. Antimicrob Agents Chemother 2017; 61:AAC.00739-17. [PMID: 28533249 DOI: 10.1128/aac.00739-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 05/18/2017] [Indexed: 11/20/2022] Open
Abstract
Soraphen A is a myxobacterial metabolite that blocks the acetyl-coenzyme A carboxylase of the host and was previously identified as a novel HIV inhibitor. Here, we report that soraphen A acts by reducing virus production and altering the gp120 virion content, impacting entry capacity and infectivity. These effects are partially reversed by addition of palmitic acid, suggesting that inhibition of HIV envelope palmitoylation is one of the mechanisms of antiviral action.
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4
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Spencer A, Yu L, Guili V, Reynaud F, Ding Y, Ma J, Jullien J, Koubi D, Gauthier E, Cluet D, Falk J, Castellani V, Yuan C, Rudkin BB. Nerve Growth Factor Signaling from Membrane Microdomains to the Nucleus: Differential Regulation by Caveolins. Int J Mol Sci 2017; 18:E693. [PMID: 28338624 PMCID: PMC5412279 DOI: 10.3390/ijms18040693] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 03/08/2017] [Accepted: 03/13/2017] [Indexed: 11/16/2022] Open
Abstract
Membrane microdomains or "lipid rafts" have emerged as essential functional modules of the cell, critical for the regulation of growth factor receptor-mediated responses. Herein we describe the dichotomy between caveolin-1 and caveolin-2, structural and regulatory components of microdomains, in modulating proliferation and differentiation. Caveolin-2 potentiates while caveolin-1 inhibits nerve growth factor (NGF) signaling and subsequent cell differentiation. Caveolin-2 does not appear to impair NGF receptor trafficking but elicits prolonged and stronger activation of MAPK (mitogen-activated protein kinase), Rsk2 (ribosomal protein S6 kinase 2), and CREB (cAMP response element binding protein). In contrast, caveolin-1 does not alter initiation of the NGF signaling pathway activation; rather, it acts, at least in part, by sequestering the cognate receptors, TrkA and p75NTR, at the plasma membrane, together with the phosphorylated form of the downstream effector Rsk2, which ultimately prevents CREB phosphorylation. The non-phosphorylatable caveolin-1 serine 80 mutant (S80V), no longer inhibits TrkA trafficking or subsequent CREB phosphorylation. MC192, a monoclonal antibody towards p75NTR that does not block NGF binding, prevents exit of both NGF receptors (TrkA and p75NTR) from lipid rafts. The results presented herein underline the role of caveolin and receptor signaling complex interplay in the context of neuronal development and tumorigenesis.
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MESH Headings
- Animals
- Antibodies, Monoclonal/immunology
- CREB-Binding Protein/metabolism
- Caveolin 1/antagonists & inhibitors
- Caveolin 1/genetics
- Caveolin 1/metabolism
- Caveolin 2/antagonists & inhibitors
- Caveolin 2/genetics
- Caveolin 2/metabolism
- Cell Differentiation/drug effects
- Cell Nucleus/metabolism
- Cells, Cultured
- Ganglia, Spinal/cytology
- Ganglia, Spinal/metabolism
- Membrane Microdomains/metabolism
- Mice
- Nerve Growth Factor/pharmacology
- Nerve Tissue Proteins
- PC12 Cells
- Phosphorylation/drug effects
- Protein Binding
- Protein Transport/drug effects
- RNA Interference
- RNA, Small Interfering/metabolism
- Rats
- Receptor, Nerve Growth Factor/metabolism
- Receptor, trkA/chemistry
- Receptor, trkA/immunology
- Receptor, trkA/metabolism
- Receptors, Growth Factor
- Receptors, Nerve Growth Factor/chemistry
- Receptors, Nerve Growth Factor/immunology
- Receptors, Nerve Growth Factor/metabolism
- Ribosomal Protein S6 Kinases, 90-kDa/metabolism
- Signal Transduction/drug effects
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Affiliation(s)
- Ambre Spencer
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
- East China Normal University, School of Life Sciences, Laboratory of Molecular and Cellular Neurophysiology, Shanghai 200062, China.
| | - Lingli Yu
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
- East China Normal University, School of Life Sciences, Laboratory of Molecular and Cellular Neurophysiology, Shanghai 200062, China.
| | - Vincent Guili
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
| | - Florie Reynaud
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, CGphiMC UMR5534, 69622 Villeurbanne Cedex, France.
| | - Yindi Ding
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
- East China Normal University, School of Life Sciences, Laboratory of Molecular and Cellular Neurophysiology, Shanghai 200062, China.
| | - Ji Ma
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- East China Normal University, School of Life Sciences, Laboratory of Molecular and Cellular Neurophysiology, Shanghai 200062, China.
| | - Jérôme Jullien
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
| | - David Koubi
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
| | - Emmanuel Gauthier
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
| | - David Cluet
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
| | - Julien Falk
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, CGphiMC UMR5534, 69622 Villeurbanne Cedex, France.
| | - Valérie Castellani
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, CGphiMC UMR5534, 69622 Villeurbanne Cedex, France.
| | - Chonggang Yuan
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- East China Normal University, School of Life Sciences, Laboratory of Molecular and Cellular Neurophysiology, Shanghai 200062, China.
| | - Brian B Rudkin
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
- Univ. Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, 69500 Bron, France.
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5
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Gajate C, Mollinedo F. Isolation of Lipid Rafts Through Discontinuous Sucrose Gradient Centrifugation and Fas/CD95 Death Receptor Localization in Raft Fractions. Methods Mol Biol 2017; 1557:125-138. [PMID: 28078589 DOI: 10.1007/978-1-4939-6780-3_13] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Lipid raft domains, enriched in sphingolipids and cholesterol, serve as sorting platforms and hubs for signal transduction proteins, and show resistance to detergent solubilization. Despite rafts have been involved in survival processes, these membrane domains have also been shown to play a major role in the modulation of death receptor signaling. Here, we describe a detailed protocol for isolating lipid rafts from whole cells by taking advantage of the lipid raft resistance to Triton X-100 solubilization at 4 °C, followed by sucrose gradient centrifugation, with subsequent analysis of Fas/CD95 death receptor localization in the raft fractions by immunoblotting. This method is also useful to localize additional proteins in membrane rafts.
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Affiliation(s)
- Consuelo Gajate
- Laboratory of Cell Death and Cancer Therapy, Department of Cellular and Molecular Medicine, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), C/ Ramiro de Maeztu 9, 28040, Madrid, Spain.
| | - Faustino Mollinedo
- Laboratory of Cell Death and Cancer Therapy, Department of Cellular and Molecular Medicine, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), C/ Ramiro de Maeztu 9, 28040, Madrid, Spain.
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6
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Abstract
The hypothesis that the Golgi apparatus is capable of sorting proteins and sending them to the plasma membrane through "lipid rafts," membrane lipid domains highly enriched in glycosphingolipids, sphingomyelin, ceramide, and cholesterol, was formulated by van Meer and Simons in 1988 and came to a turning point when it was suggested that lipid rafts could be isolated thanks to their resistance to solubilization by some detergents, namely Triton X-100. An incredible number of papers have described the composition and properties of detergent-resistant membrane fractions. However, the use of this method has also raised the fiercest criticisms. In this chapter, we would like to discuss the most relevant methodological aspects related to the preparation of detergent-resistant membrane fractions, and to discuss the importance of discriminating between what is present on a cell membrane and what we can prepare from cell membranes in a laboratory tube.
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7
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De Nicola A, Kawakatsu T, Rosano C, Celino M, Rocco M, Milano G. Self-Assembly of Triton X-100 in Water Solutions: A Multiscale Simulation Study Linking Mesoscale to Atomistic Models. J Chem Theory Comput 2015; 11:4959-71. [DOI: 10.1021/acs.jctc.5b00485] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Antonio De Nicola
- Dipartimento
di Chimica e Biologia, Università di Salerno, I-84084 via
Ponte don Melillo, Salerno, Italy
| | - Toshihiro Kawakatsu
- Department
of Physics, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Camillo Rosano
- Biopolimeri
e Proteomica, IRCCS AOU San Martino-IST, Istituto Nazionale per la Ricerca sul Cancro, Largo R. Benzi 10 I-16132 Genova, Italy
| | - Massimo Celino
- ENEA, C.R. Casaccia, Via Anguillarese 301, I-00123 Roma, Italy
| | - Mattia Rocco
- Biopolimeri
e Proteomica, IRCCS AOU San Martino-IST, Istituto Nazionale per la Ricerca sul Cancro, Largo R. Benzi 10 I-16132 Genova, Italy
| | - Giuseppe Milano
- Dipartimento
di Chimica e Biologia, Università di Salerno, I-84084 via
Ponte don Melillo, Salerno, Italy
- IMAST S.c.a.r.l.
Technological District in Polymer and Composite Engineering, P. leBovio 22, I-80133, Napoli, Italy
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8
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Casadei BR, De Oliveira Carvalho P, Riske KA, Barbosa RDM, De Paula E, Domingues CC. Brij detergents reveal new aspects of membrane microdomain in erythrocytes. Mol Membr Biol 2015; 31:195-205. [PMID: 25222860 DOI: 10.3109/09687688.2014.949319] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Membrane microdomains enriched in cholesterol, sphingolipids (rafts), and specific proteins are involved in important physiological functions. However their structure, size and stability are still controversial. Given that detergent-resistant membranes (DRMs) are in the liquid-ordered state and are rich in raft-like components, they might correspond to rafts at least to some extent. Here we monitor the lateral order of biological membranes by characterizing DRMs from erythrocytes obtained with Brij-98, Brij-58, and TX-100 at 4 °C and 37 °C. All DRMs were enriched in cholesterol and contained the raft markers flotillin-2 and stomatin. However, sphingomyelin (SM) was only found to be enriched in TX-100-DRMs - a detergent that preferentially solubilizes the membrane inner leaflet - while Band 3 was present solely in Brij-DRMs. Electron paramagnetic resonance spectra showed that the acyl chain packing of Brij-DRMs was lower than TX-100-DRMs, providing evidence of their diverse lipid composition. Fatty acid analysis revealed that the SM fraction of the DRMs was enriched in lignoceric acid, which should specifically contribute to the resistance of SM to detergents. These results indicate that lipids from the outer leaflet, particularly SM, are essential for the formation of the liquid-ordered phase of DRMs. At last, the differential solubilization process induced by Brij-98 and TX-100 was monitored using giant unilamellar vesicles. This study suggests that Brij and TX-100-DRMs reflect different degrees of lateral order of the membrane microdomains. Additionally, Brij DRMs are composed by both inner and outer leaflet components, making them more physiologically relevant than TX-100-DRMs to the studies of membrane rafts.
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Affiliation(s)
- Bruna Renata Casadei
- Departamento de Bioquímica e Biologia Tecidual, Instituto de Biologia, Universidade Estadual de Campinas (Unicamp) , Campinas , Brazil
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9
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Casadei BR, Domingues CC, de Paula E, Riske KA. Direct visualization of the action of Triton X-100 on giant vesicles of erythrocyte membrane lipids. Biophys J 2015; 106:2417-25. [PMID: 24896120 DOI: 10.1016/j.bpj.2014.04.039] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 04/22/2014] [Accepted: 04/29/2014] [Indexed: 11/24/2022] Open
Abstract
The raft hypothesis proposes that microdomains enriched in sphingolipids, cholesterol, and specific proteins are transiently formed to accomplish important cellular tasks. Equivocally, detergent-resistant membranes were initially assumed to be identical to membrane rafts, because of similarities between their compositions. In fact, the impact of detergents in membrane organization is still controversial. Here, we use phase contrast and fluorescence microscopy to observe giant unilamellar vesicles (GUVs) made of erythrocyte membrane lipids (erythro-GUVs) when exposed to the detergent Triton X-100 (TX-100). We clearly show that TX-100 has a restructuring action on biomembranes. Contact with TX-100 readily induces domain formation on the previously homogeneous membrane of erythro-GUVs at physiological and room temperatures. The shape and dynamics of the formed domains point to liquid-ordered/liquid-disordered (Lo/Ld) phase separation, typically found in raft-like ternary lipid mixtures. The Ld domains are then separated from the original vesicle and completely solubilized by TX-100. The insoluble vesicle left, in the Lo phase, represents around 2/3 of the original vesicle surface at room temperature and decreases to almost 1/2 at physiological temperature. This chain of events could be entirely reproduced with biomimetic GUVs of a simple ternary lipid mixture, 2:1:2 POPC/SM/chol (phosphatidylcholine/sphyngomyelin/cholesterol), showing that this behavior will arise because of fundamental physicochemical properties of simple lipid mixtures. This work provides direct visualization of TX-100-induced domain formation followed by selective (Ld phase) solubilization in a model system with a complex biological lipid composition.
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Affiliation(s)
- Bruna R Casadei
- Departamento de Bioquímica, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil
| | - Cleyton C Domingues
- Departamento de Bioquímica, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil
| | - Eneida de Paula
- Departamento de Bioquímica, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil
| | - Karin A Riske
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, Brazil.
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10
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Mattei B, França ADC, Riske KA. Solubilization of binary lipid mixtures by the detergent Triton X-100: the role of cholesterol. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 31:378-386. [PMID: 25474726 DOI: 10.1021/la504004r] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The solubilization of lipid bilayers of different composition and phase by the detergent Triton X-100 (Triton X-100) was investigated using optical and fluorescence microscopy of giant unilamellar vesicles (GUVs) and light scattering of large unilamellar vesicles (LUVs). The compositions explored were 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), in the liquid-disordered (Ld) phase, sphingomyelin (SM), in the gel phase, and binary mixtures of these phospholipids with 30 mol % cholesterol (chol), resulting in bilayers in the Ld and liquid-ordered (Lo) phases, respectively. We show that the phospholipid bilayers are completely soluble in TX-100, but optical microscopy reveals that whereas fluid POPC is gradually solubilized by TX-100, gel SM is first shattered in bilayer fragments. Incorporation of TX-100 in the membrane leads to increase in GUV area, which was quantified and expressed as bound detergent-to-lipid molar ratio. The partition of TX-100 in POPC is very high, decreases in POPC/chol, and is negligible in SM/chol. Fluorescence microscopy shows that TX-100 induces Lo/Ld phase separation in previously homogeneous POPC/chol GUVs, and insoluble bilayer fragments/vesicles are detected with optical microscopy and light scattering. Vesicles of SM/chol, in the Lo phase, are virtually insoluble in TX-100. Taken together, our results show that the presence of cholesterol is the origin of membrane resistance to solubilization, which depending on the specific lipid mixture can result in either partially (POPC/chol) or completely (SM/chol) insoluble mixtures.
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Affiliation(s)
- Bruno Mattei
- Departamento de Biofísica, Universidade Federal de São Paulo , São Paulo, Brazil
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11
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Hauser JT, Lindner R. Coalescence of B cell receptor and invariant chain MHC II in a raft-like membrane domain. J Leukoc Biol 2014; 96:843-55. [PMID: 25024398 DOI: 10.1189/jlb.2a0713-353r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The BCR binds antigen for processing and subsequent presentation on MHC II molecules. Polyvalent antigen induces BCR clustering and targeting to endocytic processing compartments, which are also accessed by Ii-MHC II. Here, we report that clustered BCR is able to team up with Ii-MHC II already at the plasma membrane of mouse B-lymphocytes. Colocalization of BCR and Ii-MHC II on the cell surface required clustering of both types of molecules. The clustering of only one type did not trigger the recruitment of the other. Ii-bound MIF (a ligand of Ii) also colocalized with clustered BCR upon oligomerization of MIF on the surface of the B cell. Abundant surface molecules, such as B220 or TfnR, did not cocluster with the BCR. Some membrane raft-associated molecules, such as peptide-loaded MHC II, coclustered with the BCR, whereas others, such as GM1, did not. The formation of a BCR- and Ii-MHC II-containing membrane domain by antibody-mediated clustering was independent of F-actin and led to the coendocytosis of its constituents. With a rapid Brij 98 extraction method, it was possible to capture this membrane domain biochemically as a DRM. Ii and clustered BCR were present on the same DRM, as shown by immunoisolation. The coalescence of BCR and Ii-MHC II increased tyrosine phosphorylation, indicative of enhanced BCR signaling. Our work suggests a novel role for MIF and Ii-MHC II in BCR-mediated antigen processing.
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Affiliation(s)
- Julian T Hauser
- Hannover Medical School, Department of Cell Biology, Center for Anatomy, Hannover, Germany
| | - Robert Lindner
- Hannover Medical School, Department of Cell Biology, Center for Anatomy, Hannover, Germany
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12
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Illien F, Piao HR, Coué M, di Marco C, Ayala-Sanmartin J. Lipid organization regulates annexin A2 Ca2+-sensitivity for membrane bridging and its modulator effects on membrane fluidity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2892-900. [DOI: 10.1016/j.bbamem.2012.07.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 07/03/2012] [Accepted: 07/17/2012] [Indexed: 10/28/2022]
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13
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Curvature factor and membrane solubilization, with particular reference to membrane rafts. Cell Biol Int 2012; 35:991-5. [PMID: 21438858 DOI: 10.1042/cbi20100786] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The composition of membrane rafts (cholesterol/sphingolipid-rich domains) cannot be fully deduced from the analysis of a detergent-resistant membrane fraction after solubilization in Triton X-100 at 4°C. It is hypothesized that the membrane curvature-dependent lateral distribution of membrane components affects their solubilization. The stomatocytogenic, Triton X-100, cannot effectively solubilize membrane components, especially with regard to the outward membrane curvature.
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Mikhalyov I, Samsonov A. Lipid raft detecting in membranes of live erythrocytes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1930-9. [DOI: 10.1016/j.bbamem.2011.04.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 03/15/2011] [Accepted: 04/04/2011] [Indexed: 11/27/2022]
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The effects of membrane compartmentalization of csk on TCR signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:367-76. [PMID: 21167217 DOI: 10.1016/j.bbamcr.2010.12.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 11/16/2010] [Accepted: 12/06/2010] [Indexed: 12/29/2022]
Abstract
The TCR signal transduction is initiated by the activation of Src-family kinases (SFK) which phosphorylate Immunoreceptor tyrosine-based activation motifs (ITAM) present in the intracellular parts of the T-cell receptor (TCR) signaling subunits. Numerous data suggest that after stimulation TCR interacts with membrane rafts and thus it gains access to SFK and other important molecules involved in signal transduction. However, the precise mechanism of this process is unclear. One of the key questions is how SFK access TCR and what is the importance of non-raft and membrane raft-associated SFK for the initiation and maintenance of the TCR signaling. To answer this question we targeted a negative regulator of SFK, C-terminal Src kinase (Csk) to membrane rafts, recently described "heavy rafts" or non-raft membrane. Our data show that only Csk targeted into "classical" raft but not to "heavy raft" or non-raft membrane effectively inhibits TCR signaling, demonstrating the critical role of membrane raft-associated SFK in this process.
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del Toro D, Xifró X, Pol A, Humbert S, Saudou F, Canals JM, Alberch J. Altered cholesterol homeostasis contributes to enhanced excitotoxicity in Huntington's disease. J Neurochem 2010; 115:153-67. [PMID: 20663016 DOI: 10.1111/j.1471-4159.2010.06912.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Recent findings suggest that altered cholesterol homeostasis may contribute to the pathophysiology of Huntington's disease (HD). To understand the underlying mechanisms, here we used a combination of two-photon microscopy, epifluorescence, and biochemical methods to visualize and quantify lipid distribution in cell cultures expressing mutant huntingtin. Such expression promotes lipid imbalance, and cholesterol accumulation in cellular and murine models and in HD-affected human brains. Interestingly, cells expressing mutant huntingtin also showed higher content of ordered domains in their plasma membranes. These findings correlated with high levels of caveolin-1 and glycosphingolipid GM1, two well-defined markers of cholesterol-enriched domains, at the cell surface. In addition, cells expressing mutant huntingtin showed increased localization of NMDA receptors with cholesterol-enriched domains, contributing to increased NMDA receptor susceptibility to excitotoxic insults. Treatment with simvastatin or β-cyclodextrin, two cholesterol-lowering drugs, reduced the content of ordered domains at the cell surface, which in turn, protected cells against NMDA-mediated excitotoxicity. Taken together, our results indicate that mutant huntingtin produces accumulation of cholesterol and alters its cellular distribution that contributes to NMDA-mediated excitotoxicity. Administration of drugs that recover this effect, such as simvastatin could be beneficial for the treatment of HD.
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Affiliation(s)
- Daniel del Toro
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain
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Quinn PJ. A lipid matrix model of membrane raft structure. Prog Lipid Res 2010; 49:390-406. [PMID: 20478335 DOI: 10.1016/j.plipres.2010.05.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 05/06/2010] [Indexed: 12/12/2022]
Abstract
Domains in cell membranes are created by lipid-lipid interactions and are referred to as membrane rafts. Reliable isolation methods have been developed which have shown that rafts from the same membranes have different proteins and can be sub-fractionated by immunoaffinity methods. Analysis of these raft subfractions shows that they are also comprised of different molecular species of lipids. The major lipid classes present are phospholipids, glycosphingolipids and cholesterol. Model studies show that mixtures of phospholipids, particularly sphingomyelin, and cholesterol form liquid-ordered phase with properties intermediate between a gel and fluid phase. This type of liquid-ordered phase dominates theories of domain formation and raft structure in biological membranes. Recently it has been shown that sphingolipids with long (22-26C) N-acyl fatty acids form quasi-crystalline bilayer structures with diacylphospholipids that have well-defined stoichiometries. A two tier heuristic model of membrane raft structure is proposed in which liquid-ordered phase created by a molecular complex between sphingolipids with hydrocarbon chains of approximately equal length and cholesterol acts as a primary staging area for selecting raft proteins. Tailoring of the lipid anchors of raft proteins takes place at this site. Assembly of lipid-anchored proteins on a scaffold of sphingolipids with asymmetric hydrocarbon chains and phospholipids arranged in a quasi-crystalline bilayer structure serves to concentrate and orient the proteins in a manner that couples them functionally within the membrane. Specificity is inherent in the quasi-crystalline lipid structure of liquid-ordered matrices formed by both types of complex into which protein lipid anchors are interpolated. An interaction between the sugar residues of the glycolipids and the raft proteins provides an additional level of specificity that distinguishes one raft from another.
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Affiliation(s)
- Peter J Quinn
- Biochemistry Department, King's College London, 150 Stamford Street, London, UK.
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Proschogo N, Gaus K, Jessup W. Taking aim at cell lipids: shotgun lipidomics and imaging mass spectrometry push the boundaries. Curr Opin Lipidol 2009; 20:522-3. [PMID: 19935201 DOI: 10.1097/mol.0b013e32833301cb] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Abstract
Exocytosis is a highly conserved and essential process. Although numerous proteins are involved throughout the exocytotic process, the defining membrane fusion step appears to occur through a lipid-dominated mechanism. Here we review and integrate the current literature on protein and lipid roles in exocytosis, with emphasis on the multiple roles of cholesterol in exocytosis and membrane fusion, in an effort to promote a more molecular systems-level view of the as yet poorly understood process of Ca2+-triggered membrane mergers.
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