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Zaborowska M, Broniatowski M, Fontaine P, Bilewicz R, Matyszewska D. Statin Action Targets Lipid Rafts of Cell Membranes: GIXD/PM-IRRAS Investigation of Langmuir Monolayers. J Phys Chem B 2023; 127:7135-7147. [PMID: 37551973 PMCID: PMC10440791 DOI: 10.1021/acs.jpcb.3c02574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 07/17/2023] [Indexed: 08/09/2023]
Abstract
Lipid rafts are condensed regions of cell membranes rich in cholesterol and sphingomyelin, which constitute the target for anticholesterolemic drugs - statins. In this work, we use for the first time a combined grazing-incidence X-ray diffraction (GIXD)/polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS)/Brewster angle microscopy (BAM) approach to show the statin effect on model lipid rafts and its components assembled in Langmuir monolayers at the air-water interface. Two representatives of these drugs, fluvastatin (FLU) and cerivastatin (CER), of different hydrophobicity were chosen, while cholesterol (Chol) and sphingomyelin (SM), and their 1:1 mixture were selected to form condensed monolayers of lipid rafts. The effect of statins on the single components of lipid rafts indicated that both the hydrophobicity of the drugs and the organization of the layer determined the drug-lipid interaction. For cholesterol monolayers, only the most hydrophobic CER was effectively changing the film structure, while for the less organized sphingomyelin, the biggest effect was observed for FLU. This drug affected both the polar headgroup region as shown by PM-IRRAS results and the 2D crystalline structure of the SM monolayer as evidenced by GIXD. Measurements performed for Chol/SM 1:1 models proved also that the statin effect depends on the presence of Chol-SM complexes. In this case, the less hydrophobic FLU was not able to penetrate the binary layer at all, while exposure to the hydrophobic CER resulted in the phase separation and formation of ordered assemblies. The changes in the membrane properties were visualized by BAM images and GIXD patterns and confirmed by thermodynamic parameters of hysteresis in the Langmuir monolayer compression-decompression experiments.
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Affiliation(s)
| | - Marcin Broniatowski
- Faculty
of Chemistry, Jagiellonian University, Gronostajowa 2, 30387 Kraków, Poland
| | - Philippe Fontaine
- Synchrotron
SOLEIL, L’Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
| | - Renata Bilewicz
- Faculty
of Chemistry, University of Warsaw, Pasteura 1, 02093 Warsaw, Poland
| | - Dorota Matyszewska
- Faculty
of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02089 Warsaw, Poland
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2
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Matthews CEP, Fussner LA, Yaeger M, Aloor JJ, Reece SW, Kilburg-Basnyat BJ, Varikuti S, Luo B, Inks M, Sergin S, Schmidt CA, Neufer PD, Pennington ER, Fisher-Wellman KH, Chowdhury SM, Fessler MB, Fenton JI, Anderson EJ, Shaikh SR, Gowdy KM. The prohibitin complex regulates macrophage fatty acid composition, plasma membrane packing, and lipid raft-mediated inflammatory signaling. Prostaglandins Leukot Essent Fatty Acids 2023; 190:102540. [PMID: 36706677 PMCID: PMC9992117 DOI: 10.1016/j.plefa.2023.102540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 12/28/2022] [Accepted: 01/15/2023] [Indexed: 01/20/2023]
Abstract
Prohibitins (PHB1 and PHB2) are ubiquitously expressed proteins which play critical roles in multiple biological processes, and together form the ring-like PHB complex found in phospholipid-rich cellular compartments including lipid rafts. Recent studies have implicated PHB1 as a mediator of fatty acid transport as well as a membrane scaffold mediating B lymphocyte and mast cell signal transduction. However, the specific role of PHBs in the macrophage have not been characterized, including their role in fatty acid uptake and lipid raft-mediated inflammatory signaling. We hypothesized that the PHB complex regulates macrophage inflammatory signaling through the formation of lipid rafts. To evaluate our hypothesis, RAW 264.7 macrophages were transduced with shRNA against PHB1, PHB2, or scrambled control (Scr), and then stimulated with lipopolysaccharide (LPS) or tumor necrosis factor-alpha (TNF-α), which activate lipid raft-dependent receptor signaling (CD14/TLR4 and TNFR1, respectively). PHB1 knockdown was lethal, whereas PHB2 knockdown (PHB2kd), which also resulted in decreased PHB1 expression, led to attenuated nuclear factor-kappa-B (NF-κB) activation and subsequent cytokine and chemokine production. PHB2kd macrophages also had decreased cell surface TNFR1, CD14, TLR4, and lipid raft marker ganglioside GM1 at baseline and post-stimuli. Post-LPS, PHB2kd macrophages did not increase the concentration of cellular saturated, monounsaturated, and polyunsaturated fatty acids. This was accompanied by decreased lipid raft formation and modified plasma membrane molecular packing, further supporting the PHB complex's importance in lipid raft formation. Taken together, these data suggest a critical role for PHBs in regulating macrophage inflammatory signaling via maintenance of fatty acid composition and lipid raft structure. SUMMARY: Prohibitins are proteins found in phospholipid-rich cellular compartments, including lipid rafts, that play important roles in signaling, transcription, and multiple other cell functions. Macrophages are key cells in the innate immune response and the presence of membrane lipid rafts is integral to signal transduction, but the role of prohibitins in macrophage lipid rafts and associated signaling is unknown. To address this question, prohibitin knockdown macrophages were generated and responses to lipopolysaccharide and tumor necrosis factor-alpha, which act through lipid raft-dependent receptors, were analyzed. Prohibitin knockdown macrophages had significantly decreased cytokine and chemokine production, transcription factor activation, receptor expression, lipid raft assembly and membrane packing, and altered fatty acid remodeling. These data indicate a novel role for prohibitins in macrophage inflammatory signaling through regulation of fatty acid composition and lipid raft formation.
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Affiliation(s)
- Christine E Psaltis Matthews
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Lynn A Fussner
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, The Ohio State University, Columbus, OH, United States
| | - Michael Yaeger
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, The Ohio State University, Columbus, OH, United States
| | - Jim J Aloor
- Diabetes and Obesity Institute, Department of Physiology, East Carolina University, Greenville, NC, United States
| | - Sky W Reece
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Brita J Kilburg-Basnyat
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Sanjay Varikuti
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, The Ohio State University, Columbus, OH, United States
| | - Bin Luo
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Morgan Inks
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, The Ohio State University, Columbus, OH, United States
| | - Selin Sergin
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI, United States
| | - Cameron A Schmidt
- Diabetes and Obesity Institute, Department of Physiology, East Carolina University, Greenville, NC, United States
| | - P Darrell Neufer
- Diabetes and Obesity Institute, Department of Physiology, East Carolina University, Greenville, NC, United States
| | - Edward Ross Pennington
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, University of North Carolina, Chapel Hill, NC, United States
| | - Kelsey H Fisher-Wellman
- Diabetes and Obesity Institute, Department of Physiology, East Carolina University, Greenville, NC, United States
| | - Saiful M Chowdhury
- Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, TX, United States
| | - Michael B Fessler
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC, United States
| | - Jenifer I Fenton
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI, United States
| | - Ethan J Anderson
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, FOE Diabetes Research Center, University of Iowa, Iowa City, IA, United States
| | - Saame Raza Shaikh
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, University of North Carolina, Chapel Hill, NC, United States
| | - Kymberly M Gowdy
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, The Ohio State University, Columbus, OH, United States.
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Ghosh S, Mishra P, Banerjee S, Maiti K, Khopade A, Misra A, Sawant K, Bhowmick S. Exploration of the cardinal formulation parameters influencing the encapsulation and physicochemical properties of co-loaded anticancer dual drug nanoliposomes. J Drug Deliv Sci Technol 2022. [DOI: 10.1016/j.jddst.2022.103295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
Cholesterol is a key steroidal, lipid biomolecule found abundantly in plasma membranes of eukaryotic cells. It is an important structural component of cellular membranes and regulates membrane fluidity and permeability. Cholesterol is also essential for normal functioning of key proteins including ion-channels, G protein-coupled receptors (GPCRs), membrane bound steroid receptors, and receptor kinases. It is thought that cholesterol exerts its actions via specific binding to chiral proteins and lipids as well as through non-specific physiochemical interactions. Distinguishing between the specific and the non-specific interactions can be difficult. Although much remains unclear, progress has been made in recent years by utilizing ent-cholesterol, the enantiomer of natural cholesterol (nat-cholesterol) as a probe. Ent-Cholesterol is the non-superimposable mirror image of nat-cholesterol and exhibits identical physiochemical properties as nat-cholesterol. Hence, if the biological effects of cholesterol result solely due to membrane effects, it is expected that there will be no difference between ent-cholesterol and nat-cholesterol. However, when direct binding with chiral proteins and lipids is involved, the enantiomer is expected to potentially elicit significantly different, measurable effects due to formation of diastereomeric complexes. In this chapter, we have reviewed the literature related to ent-cholesterol and its use as a probe for various biophysical and biological interactions of cholesterol.
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Role of Transmembrane Proteins for Phase Separation and Domain Registration in Asymmetric Lipid Bilayers. Biomolecules 2019; 9:biom9080303. [PMID: 31349669 PMCID: PMC6723173 DOI: 10.3390/biom9080303] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 07/19/2019] [Accepted: 07/22/2019] [Indexed: 02/05/2023] Open
Abstract
It is well known that the formation and spatial correlation of lipid domains in the two apposed leaflets of a bilayer are influenced by weak lipid–lipid interactions across the bilayer’s midplane. Transmembrane proteins span through both leaflets and thus offer an alternative domain coupling mechanism. Using a mean-field approximation of a simple bilayer-type lattice model, with two two-dimensional lattices stacked one on top of the other, we explore the role of this “structural” inter-leaflet coupling for the ability of a lipid membrane to phase separate and form spatially correlated domains. We present calculated phase diagrams for various effective lipid–lipid and lipid–protein interaction strengths in membranes that contain a binary lipid mixture in each leaflet plus a small amount of added transmembrane proteins. The influence of the transmembrane nature of the proteins is assessed by a comparison with “peripheral” proteins, which result from the separation of one single integral protein into two independent units that are no longer structurally connected across the bilayer. We demonstrate that the ability of membrane-spanning proteins to facilitate domain formation requires sufficiently strong lipid–protein interactions. Weak lipid–protein interactions generally tend to inhibit phase separation in a similar manner for transmembrane as for peripheral proteins.
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6
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A novel family of mammalian transmembrane proteins involved in cholesterol transport. Sci Rep 2017; 7:7450. [PMID: 28785058 PMCID: PMC5547113 DOI: 10.1038/s41598-017-07077-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 06/22/2017] [Indexed: 11/20/2022] Open
Abstract
Cholesterol is an essential compound in mammalian cells because it is involved in a wide range of functions, including as a key component of membranes, precursor of important molecules such as hormones, bile acids and vitamin D. The cholesterol transport across the circulatory system is a well-known process in contrast to the intracellular cholesterol transport, which is poorly understood. Recently in our laboratory, we identified a novel protein in C. elegans involved in dietary cholesterol uptake, which we have named ChUP-1. Insillicoanalysis identified two putative orthologue candidate proteins in mammals. The proteins SIDT1 and SIDT2 share identity and conserved cholesterol binding (CRAC) domains with C. elegans ChUP-1. Both mammalian proteins are annotated as RNA transporters in databases. In the present study, we show evidence indicating that SIDT1 and SIDT2 not only do not transport RNA, but they are involved in cholesterol transport. Furthermore, we show that single point mutations directed to disrupt the CRAC domains of both proteins prevent FRET between SIDT1 and SIDT2 and the cholesterol analogue dehydroergosterol (DHE) and alter cholesterol transport.
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7
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Beck Z, Matyas GR, Alving CR. Detection of liposomal cholesterol and monophosphoryl lipid A by QS-21 saponin and Limulus polyphemus amebocyte lysate. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:775-80. [DOI: 10.1016/j.bbamem.2014.12.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/26/2014] [Accepted: 12/05/2014] [Indexed: 11/16/2022]
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8
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Posada IMD, Fantini J, Contreras FX, Barrantes F, Alonso A, Goñi FM. A cholesterol recognition motif in human phospholipid scramblase 1. Biophys J 2015; 107:1383-92. [PMID: 25229146 DOI: 10.1016/j.bpj.2014.07.039] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 06/28/2014] [Accepted: 07/22/2014] [Indexed: 11/26/2022] Open
Abstract
Human phospholipid scramblase 1 (SCR) catalyzes phospholipid transmembrane (flip-flop) motion. This protein is assumed to bind the membrane hydrophobic core through a transmembrane domain (TMD) as well as via covalently bound palmitoyl residues. Here, we explore the possible interaction of the SCR TMD with cholesterol by using a variety of experimental and computational biophysical approaches. Our findings indicate that SCR contains an amino acid segment at the C-terminal region that shows a remarkable affinity for cholesterol, although it lacks the CRAC sequence. Other 3-OH sterols, but not steroids lacking the 3-OH group, also bind this region of the protein. The newly identified cholesterol-binding region is located partly at the C-terminal portion of the TMD and partly in the first amino acid residues in the SCR C-terminal extracellular coil. This finding could be related to the previously described affinity of SCR for cholesterol-rich domains in membranes.
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Affiliation(s)
- Itziar M D Posada
- Unidad de Biofísica (CSIC, UPV/EHU), Departamento de Bioquímica y Biología Molecular, Bilbao, Spain
| | - Jacques Fantini
- Interactions Moléculaires et Systèmes Membranaires, EA-4674, Aix-Marseille Université, Marseille, France
| | - F Xabier Contreras
- Unidad de Biofísica (CSIC, UPV/EHU), Departamento de Bioquímica y Biología Molecular, Bilbao, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Francisco Barrantes
- Laboratory of Molecular Neurobiology, Faculty of Medical Sciences, Biomedical Research Institute (BIOMED) UCA-CONICET, Catholic University of Argentina, Buenos Aires, Argentina
| | - Alicia Alonso
- Unidad de Biofísica (CSIC, UPV/EHU), Departamento de Bioquímica y Biología Molecular, Bilbao, Spain
| | - Félix M Goñi
- Unidad de Biofísica (CSIC, UPV/EHU), Departamento de Bioquímica y Biología Molecular, Bilbao, Spain.
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9
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Ferraro M, Masetti M, Recanatini M, Cavalli A, Bottegoni G. Modeling lipid raft domains containing a mono-unsaturated phosphatidylethanolamine species. RSC Adv 2015. [DOI: 10.1039/c5ra02196k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
An advanced coarse-grained model for “atypical” lipid rafts was built and validated to be employed in studies of membrane-protein interactions.
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Affiliation(s)
- M. Ferraro
- D3 Compunet
- Istituto Italiano di Tecnologia
- Genova
- Italy
| | - M. Masetti
- Department of Pharmacy and Biotechnology
- Alma Mater Studiorum – Università di Bologna
- Bologna
- Italy
| | - M. Recanatini
- Department of Pharmacy and Biotechnology
- Alma Mater Studiorum – Università di Bologna
- Bologna
- Italy
| | - A. Cavalli
- D3 Compunet
- Istituto Italiano di Tecnologia
- Genova
- Italy
- Department of Pharmacy and Biotechnology
| | - G. Bottegoni
- D3 Compunet
- Istituto Italiano di Tecnologia
- Genova
- Italy
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10
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Yang G, Xu H, Li Z, Li F. Interactions of caveolin-1 scaffolding and intramembrane regions containing a CRAC motif with cholesterol in lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2588-99. [PMID: 24998359 DOI: 10.1016/j.bbamem.2014.06.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 06/13/2014] [Accepted: 06/22/2014] [Indexed: 11/27/2022]
Abstract
Caveolin-1 is a major structural protein of caveolae and specifically binds cholesterol (Chol). The caveolin scaffolding domain is thought to be involved in caveolin-Chol interaction through the sequence V94-T-K-Y-W-F-Y-R101, a motif that matches a cholesterol recognition amino-acid consensus (CRAC). In the present work, three CRAC-containing peptides, corresponding to caveolin-1 94-101, 82-101 and 93-126, were tested to study the role of the CRAC motif in the caveolin-Chol interaction in 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers using differential scanning calorimetry (DSC), fluorescence and circular dichroism (CD). The Y97I substituents of the three peptides and one peptide segment corresponding to caveolin-1 101-126 that excludes the CRAC motif were also tested for comparison. Our results showed the potency of these CRAC-containing peptides in sequestering Chol into domains and the enhanced role of the intramembrane domain and scaffolding domain for the potency. Of the three CRAC-containing peptides, the peptide 93-126 was particularly effective in promoting Chol segregation, while the peptide 82-101 was less potent in promoting the formation of domains than the peptide 93-126, but was more potent than the peptide 94-101. The domain partition of DPPC/Chol bilayers was not observed in the presence of the peptide 101-126, in contrast to the case in the presence of the peptide 93-126 at the same concentrations of peptide and Chol. The potency of the CRAC motif in Chol segregation was lowered by the Y97I mutation. The difference in structure may be a factor that contributes to different effects of these peptides on the distribution of Chol in the lipid membrane.
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Affiliation(s)
- Guanhua Yang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun, 130012, PR China
| | - Haoran Xu
- Key Laboratory for Molecular Enzymology & Engineering, The Ministry of Education, Jilin University, Changchun 130012, PR China
| | - Zhengqiang Li
- Key Laboratory for Molecular Enzymology & Engineering, The Ministry of Education, Jilin University, Changchun 130012, PR China
| | - Fei Li
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun, 130012, PR China.
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11
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Kraut R, Bag N, Wohland T. Fluorescence Correlation Methods for Imaging Cellular Behavior of Sphingolipid-Interacting Probes. Methods Cell Biol 2012; 108:395-427. [DOI: 10.1016/b978-0-12-386487-1.00018-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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12
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Fessler MB, Parks JS. Intracellular lipid flux and membrane microdomains as organizing principles in inflammatory cell signaling. THE JOURNAL OF IMMUNOLOGY 2011; 187:1529-35. [PMID: 21810617 DOI: 10.4049/jimmunol.1100253] [Citation(s) in RCA: 202] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Lipid rafts and caveolae play a pivotal role in organization of signaling by TLR4 and several other immune receptors. Beyond the simple cataloguing of signaling events compartmentalized by these membrane microdomains, recent studies have revealed the surprisingly central importance of dynamic remodeling of membrane lipid domains to immune signaling. Simple interventions upon membrane lipid, such as changes in cholesterol loading or crosslinking of raft lipids, are sufficient to induce micrometer-scale reordering of membranes and their protein cargo with consequent signal transduction. In this review, using TLR signaling in the macrophage as a central focus, we discuss emerging evidence that environmental and genetic perturbations of membrane lipid regulate protein signaling, illustrate how homeostatic flow of cholesterol and other lipids through rafts regulates the innate immune response, and highlight recent attempts to harness these insights toward therapeutic development.
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Affiliation(s)
- Michael B Fessler
- Laboratory of Respiratory Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
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13
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Martínez-Abundis E, Correa F, Rodríguez E, Soria-Castro E, Rodríguez-Zavala JS, Pacheco-Alvarez D, Zazueta C. A CRAC-like motif in BAX sequence: relationship with protein insertion and pore activity in liposomes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1888-95. [PMID: 21440528 DOI: 10.1016/j.bbamem.2011.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 01/26/2011] [Accepted: 03/21/2011] [Indexed: 02/08/2023]
Abstract
Several proteins that interact with cholesterol have a highly conserved sequence, corresponding to the cholesterol recognition/interaction amino acid consensus. Since cholesterol has been proposed to modulate both oligomerization and insertion of the pro-apoptotic protein BAX, we investigated the existence of such a motif in the BAX sequence. Residues 113 to 119 of the recombinant BAX α5-helix, LFYFASK, correspond with the sequence motif described for the consensus pattern, -L/V-(X)(1-5)-Y-(X)(1-5)-R/K. Functional characterization of the point mutations, K119A, Y115F, and L113A in BAX, was performed in liposomes supplemented with cholesterol, comparing binding, integration, and pore forming activities. Our results show that the mutations Y115F and L113A changed the cholesterol-dependent insertion observed in the wild type protein. In addition, substitutions in the BAX sequence modified the concentration dependency of carboxyfluorescein release in liposomes, although neither pore activity of the wild type or of any of the mutants significantly increased in cholesterol-enriched liposomes. Thus, while it is likely that the putative CRAC motif in BAX accounts for its enhanced insertion in cholesterol-enriched liposomes; the pore forming properties of BAX did not depend on cholesterol content in the membranes, albeit those mutations changed the pore channeling activity of the protein.
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14
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de Meyer FJM, Rodgers JM, Willems TF, Smit B. Molecular simulation of the effect of cholesterol on lipid-mediated protein-protein interactions. Biophys J 2011; 99:3629-38. [PMID: 21112287 DOI: 10.1016/j.bpj.2010.09.030] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 09/14/2010] [Accepted: 09/16/2010] [Indexed: 12/01/2022] Open
Abstract
Experiments and molecular simulations have shown that the hydrophobic mismatch between proteins and membranes contributes significantly to lipid-mediated protein-protein interactions. In this article, we discuss the effect of cholesterol on lipid-mediated protein-protein interactions as function of hydrophobic mismatch, protein diameter and protein cluster size, lipid tail length, and temperature. To do so, we study a mesoscopic model of a hydrated bilayer containing lipids and cholesterol in which proteins are embedded, with a hybrid dissipative particle dynamics-Monte Carlo method. We propose a mechanism by which cholesterol affects protein interactions: protein-induced, cholesterol-enriched, or cholesterol-depleted lipid shells surrounding the proteins affect the lipid-mediated protein-protein interactions. Our calculations of the potential of mean force between proteins and protein clusters show that the addition of cholesterol dramatically reduces repulsive lipid-mediated interactions between proteins (protein clusters) with positive mismatch, but does not affect attractive interactions between proteins with negative mismatch. Cholesterol has only a modest effect on the repulsive interactions between proteins with different mismatch.
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Affiliation(s)
- Frédérick J-M de Meyer
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California, USA.
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15
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Oliveira RG, Schneck E, Funari SS, Tanaka M, Maggio B. Equivalent aqueous phase modulation of domain segregation in myelin monolayers and bilayer vesicles. Biophys J 2010; 99:1500-9. [PMID: 20816062 DOI: 10.1016/j.bpj.2010.06.053] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Revised: 06/16/2010] [Accepted: 06/17/2010] [Indexed: 10/19/2022] Open
Abstract
Purified myelin can be spread as monomolecular films at the air/aqueous interface. These films were visualized by fluorescence and Brewster angle microscopy, showing phase coexistence at low and medium surface pressures (<20-30 mN/m). Beyond this threshold, the film becomes homogeneous or not, depending on the aqueous subphase composition. Pure water as well as sucrose, glycerol, dimethylsulfoxide, and dimethylformamide solutions (20% in water) produced monolayers that become homogeneous at high surface pressures; on the other hand, the presence of salts (NaCl, CaCl(2)) in Ringer's and physiological solution leads to phase domain microheterogeneity over the whole compression isotherm. These results show that surface heterogeneity is favored by the ionic milieu. The modulation of the phase-mixing behavior in monolayers is paralleled by the behavior of multilamellar vesicles as determined by small-angle and wide-angle x-ray scattering. The correspondence of the behavior of monolayers and multilayers is achieved only at high surface pressures near the equilibrium adsorption surface pressure; at lower surface pressures, the correspondence breaks down. The equilibrium surface tension on all subphases corresponds to that of the air/alkane interface (27 mN/m), independently on the surface tension of the clean subphase.
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Affiliation(s)
- Rafael G Oliveira
- Centro de Investigaciones en Química Biológica de Córdoba, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, Argentina.
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Rosetti C, Maggio B, Wilke N. Micron-scale phase segregation in lipid monolayers induced by myelin basic protein in the presence of a cholesterol analog. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:498-505. [DOI: 10.1016/j.bbamem.2009.11.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 10/19/2009] [Accepted: 11/07/2009] [Indexed: 12/16/2022]
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17
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Abstract
Up to now less than a handful of viral cholesterol-binding proteins have been characterized, in HIV, influenza virus and Semliki Forest virus. These are proteins with roles in virus entry or morphogenesis. In the case of the HIV fusion protein gp41 cholesterol binding is attributed to a cholesterol recognition consensus (CRAC) motif in a flexible domain of the ectodomain preceding the trans-membrane segment. This specific CRAC sequence mediates gp41 binding to a cholesterol affinity column. Mutations in this motif arrest virus fusion at the hemifusion stage and modify the ability of the isolated CRAC peptide to induce segregation of cholesterol in artificial membranes.Influenza A virus M2 protein co-purifies with cholesterol. Its proton translocation activity, responsible for virus uncoating, is not cholesterol-dependent, and the transmembrane channel appears too short for integral raft insertion. Cholesterol binding may be mediated by CRAC motifs in the flexible post-TM domain, which harbours three determinants of binding to membrane rafts. Mutation of the CRAC motif of the WSN strain attenuates virulence for mice. Its affinity to the raft-non-raft interface is predicted to target M2 protein to the periphery of lipid raft microdomains, the sites of virus assembly. Its influence on the morphology of budding virus implicates M2 as factor in virus fission at the raft boundary. Moreover, M2 is an essential factor in sorting the segmented genome into virus particles, indicating that M2 also has a role in priming the outgrowth of virus buds.SFV E1 protein is the first viral type-II fusion protein demonstrated to directly bind cholesterol when the fusion peptide loop locks into the target membrane. Cholesterol binding is modulated by another, proximal loop, which is also important during virus budding and as a host range determinant, as shown by mutational studies.
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Affiliation(s)
- Cornelia Schroeder
- Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, D-01307, Dresden, Germany.
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On the biogenesis of myelin membranes: sorting, trafficking and cell polarity. FEBS Lett 2009; 584:1760-70. [PMID: 19896485 DOI: 10.1016/j.febslet.2009.10.085] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 10/29/2009] [Accepted: 10/30/2009] [Indexed: 11/22/2022]
Abstract
In the central nervous system, a multilayered membrane layer known as the myelin sheath enwraps axons, and is required for optimal saltatory signal conductance. The sheath develops from membrane processes that extend from the plasma membrane of oligodendrocytes and displays a unique lipid and protein composition. Myelin biogenesis is carefully regulated, and multiple transport pathways involving a variety of endosomal compartments are involved. Here we briefly summarize how the major myelin proteins proteolipid protein and myelin basic protein reach the sheath, and highlight potential mechanisms involved, including the role of myelin specific lipids and cell polarity related transport pathways.
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Oreopoulos J, Yip CM. Combinatorial microscopy for the study of protein–membrane interactions in supported lipid bilayers: Order parameter measurements by combined polarized TIRFM/AFM. J Struct Biol 2009; 168:21-36. [DOI: 10.1016/j.jsb.2009.02.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 02/23/2009] [Accepted: 02/24/2009] [Indexed: 02/06/2023]
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20
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Aucoin D, Camenares D, Zhao X, Jung J, Sato T, Smith SO. High-resolution 1H MAS RFDR NMR of biological membranes. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 197:77-86. [PMID: 19121592 PMCID: PMC2802820 DOI: 10.1016/j.jmr.2008.12.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2008] [Revised: 12/02/2008] [Accepted: 12/05/2008] [Indexed: 05/08/2023]
Abstract
The combination of magic angle spinning (MAS) with the high-resolution (1)H NOESY NMR experiment is an established method for measuring through-space (1)H...(1)H dipolar couplings in biological membranes. The segmental motion of the lipid acyl chains along with the overall rotational diffusion of the lipids provides sufficient motion to average the (1)H dipolar interaction to within the range where MAS can be effective. One drawback of the approach is the relatively long NOESY mixing times needed for relaxation processes to generate significant crosspeak intensity. In order to drive magnetization transfer more rapidly, we use solid-state radiofrequency driven dipolar recoupling (RFDR) pulses during the mixing time. We compare the (1)H MAS NOESY experiment with a (1)H MAS RFDR experiment on dimyristoylphosphocholine, a bilayer-forming lipid and show that the (1)H MAS RFDR experiment provides considerably faster magnetization exchange than the standard (1)H MAS NOESY experiment. We apply the method to model compounds containing basic and aromatic amino acids bound to membrane bilayers to illustrate the ability to locate the position of aromatic groups that have penetrated to below the level of the lipid headgroups.
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Affiliation(s)
- Darryl Aucoin
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5115
| | - Devin Camenares
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5115
| | - Xin Zhao
- Institute for Protein Research, Osaka University, Osaka, Japan
| | - Jay Jung
- Department of Physics and Astronomy Center for Structural Biology, Stony Brook University, Stony Brook, NY 11794-5115
| | - Takeshi Sato
- Institute for Protein Research, Osaka University, Osaka, Japan
| | - Steven O. Smith
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5115
- Corresponding author. Tel.: 631-632-1210; Fax: 631-632-8575;
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21
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Rosetti CM, Maggio B, Oliveira RG. The self-organization of lipids and proteins of myelin at the membrane interface. Molecular factors underlying the microheterogeneity of domain segregation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1665-75. [DOI: 10.1016/j.bbamem.2008.02.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 02/08/2008] [Accepted: 02/15/2008] [Indexed: 12/12/2022]
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22
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Tamai N, Uemura M, Takeichi T, Goto M, Matsuki H, Kaneshina S. A new interpretation of eutectic behavior for distearoylphosphatidylcholine–cholesterol binary bilayer membrane. Biophys Chem 2008; 135:95-101. [DOI: 10.1016/j.bpc.2008.03.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Revised: 03/27/2008] [Accepted: 03/27/2008] [Indexed: 11/26/2022]
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Lu Y, Neo TL, Liu DX, Tam JP. Importance of SARS-CoV spike protein Trp-rich region in viral infectivity. Biochem Biophys Res Commun 2008; 371:356-60. [PMID: 18424264 PMCID: PMC2519895 DOI: 10.1016/j.bbrc.2008.04.044] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Accepted: 04/07/2008] [Indexed: 01/07/2023]
Abstract
SARS-CoV entry is mediated by spike glycoprotein. During the viral and host cellular membrane fusion, HR1 and HR2 form 6-helix bundle, positioning the fusion peptide closely to the C-terminal region of ectodomain to drive apposition and subsequent membrane fusion. Connecting to the HR2 region is a Trp-rich region which is absolutely conserved in members of coronaviruses. To investigate the importance of Trp-rich region in SARS-CoV entry, we produced different mutated S proteins using Alanine scan strategy. SARS-CoV pseudotyped with mutated S protein was used to measure viral infectivity. To restore the aromaticity of Ala-mutants, we performed rescue experiments using phenylalanine substitutions. Our results show that individually substituted Ala-mutants substantially decrease infectivity by >90%, global Ala-mutants totally abrogated infectivity. In contrast, Phe-substituted mutants are able to restore 10–25% infectivity comparing to the wild-type. The results suggest that the Trp-rich region of S protein is essential for SARS-CoV infectivity.
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Affiliation(s)
- Yanning Lu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
- Beijing Center for Diseases Prevention and Control, 16 Hepingli Middle Street, Dongcheng District, Beijing 100013, China
| | - Tuan Ling Neo
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Ding Xiang Liu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - James P. Tam
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
- The Scripps Research Institute, 5353 Parkside Drive, Jupiter, FL 33458, USA
- Corresponding author. Fax: +1 561 799 8568.
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Lorizate M, Huarte N, Sáez-Cirión A, Nieva JL. Interfacial pre-transmembrane domains in viral proteins promoting membrane fusion and fission. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1624-39. [PMID: 18222166 PMCID: PMC7094410 DOI: 10.1016/j.bbamem.2007.12.018] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 12/17/2007] [Accepted: 12/20/2007] [Indexed: 12/02/2022]
Abstract
Membrane fusion and fission underlie two limiting steps of enveloped virus replication cycle: access to the interior of the host-cell (entry) and dissemination of viral progeny after replication (budding), respectively. These dynamic processes proceed mediated by specialized proteins that disrupt and bend the lipid bilayer organization transiently and locally. We introduced Wimley–White membrane-water partitioning free energies of the amino acids as an algorithm for predicting functional domains that may transmit protein conformational energy into membranes. It was found that many viral products possess unusually extended, aromatic-rich pre-transmembrane stretches predicted to stably reside at the membrane interface. Here, we review structure–function studies, as well as data reported on the interaction of representative peptides with model membranes, all of which sustain a functional role for these domains in viral fusion and fission. Since pre-transmembrane sequences also constitute antigenic determinants in a membrane-bound state, we also describe some recent results on their recognition and blocking at membrane interface by neutralizing antibodies.
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Affiliation(s)
| | | | | | - José L. Nieva
- Corresponding author. Unidad de Biofísica, Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain. Tel.: +34 94 6013353; fax: +34 94 6013360.
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25
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Dopico AM, Tigyi GJ. A glance at the structural and functional diversity of membrane lipids. Methods Mol Biol 2007; 400:1-13. [PMID: 17951723 DOI: 10.1007/978-1-59745-519-0_1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
In the postgenomic era, spatially and temporally regulated molecular interactions as signals are beginning to take center stage in the understanding of fundamental biological events. For years, reductionism derived from the "fluid mosaic" model of the cell membrane has portrayed membrane lipids as rather passive molecules that, whereas separating biologically relevant aqueous phases, provided an environment so that membrane proteins could fulfill the specificity and selectivity required for proper cell signaling. Whereas these roles for membrane lipids still stand, the structural diversity of lipids and their complex arrangement in supramolecular assemblies have expanded such limited, although fundamental roles. Growing developments in the field of membrane lipids help to understand biological phenomena at the nanoscale domain, and reveal this heterogeneous group of organic compounds as a long underestimated group of key regulatory molecules. In this introductory chapter, brief overviews of the structural diversity of membrane lipids, the impact of different lipids on membrane properties, the vertical organization of lipids into rafts and caveolae, and the functional role of lipids as mediators of inter- and intracellular signals are provided. Any comprehensive review on membrane lipids, whether emphasizing structural or functional aspects, will require several volumes. The purpose of this chapter is to provide both introduction and rationale for the selection of topics that lie ahead in this book. For this reason, the list of references primarily includes reviews on particular issues dealing with membrane lipids wherein the reader can find further references.
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Affiliation(s)
- Alex M Dopico
- Department of Pharmacology, The University of Tennessee Health Science Center, Memphis, TN, USA
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26
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Abstract
Monolayers prepared from myelin conserve all the compositional complexity of the natural membrane when spread at the air-water interface. They show a complex pressure-dependent surface pattern that, on compression, changes from the coexistence of two liquid phases to a viscous fractal phase embedded in a liquid phase. We dissected the role of major myelin protein components, myelin basic protein (MBP), and Folch-Lees proteolipid protein (PLP) as crucial factors determining the structural dynamics of the interface. By analyzing mixtures of a single protein with the myelin lipids we found that MBP and PLP have different surface pressure-dependent behaviors. MBP stabilizes the segregation of two liquid phases at low pressures and becomes excluded from the film under compression, remaining adjacent to the interface. PLP, on the contrary, organizes a fractal-like pattern at all surface pressures when included in a monolayer of the protein-free myelin lipids but it remains mixed in the MBP-induced liquid phase. The resultant surface topography and dynamics is regulated by combined near to equilibrium and out-of-equilibrium effects. PLP appears to act as a surface skeleton for the whole components whereas MBP couples the structuring to surface pressure-dependent extrusion and adsorption processes.
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Affiliation(s)
- Carla M Rosetti
- Centro de Investigaciones en Química Biológica de Córdoba, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, Argentina
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27
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Le Guyader L, Le Roux C, Mazères S, Gaspard-Iloughmane H, Gornitzka H, Millot C, Mingotaud C, Lopez A. Changes of the membrane lipid organization characterized by means of a new cholesterol-pyrene probe. Biophys J 2007; 93:4462-73. [PMID: 17766338 PMCID: PMC2098716 DOI: 10.1529/biophysj.107.112821] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We synthesized 3β-hydroxy-pregn-5-ene-21-(1-methylpyrenyl)-20-methylidene (Py-met-chol), consisting of cholesterol steroid rings connected to a pyrene group via a linker without polar atoms. This compound has interesting spectroscopic properties when probing membranes: 1), The pyrene has hypochromic properties resulting from probe self-association processes in membranes. Using liposomes of various lipid compositions, we determined the association constants of the probe (K): KDOPC ≫ KPOPC ≫ KDMPC > KDMPC/15 mol % Chol > KDMPC/30 mol % Chol. This indicates a better probe solvation in saturated than in unsaturated lipids, and this effect is enhanced as the cholesterol concentration increases. 2), The pyrene fluorophore is characterized by monomer (I1–I5) and excimer (IE) emission bands. In model membranes, I1/I3 and IE/I3 ratios revealed a correlation between the polarity of the lipid core of the membrane and the amount of cholesterol. 3), Using this probe, we monitored the first steps of the signaling pathway of the mouse δ-opioid receptor, a G-protein-coupled receptor. The thickness of the membrane around this receptor is known to change after agonist binding. Fluorescence spectra of living Chinese hamster ovary cells overexpressing mouse δ-opioid receptor specifically revealed the agonist binding. These results indicate that Py-met-chol may be useful for screening ligands of this family of receptors.
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28
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Glukhov E, Shulga YV, Epand RF, Dicu AO, Topham MK, Deber CM, Epand RM. Membrane interactions of the hydrophobic segment of diacylglycerol kinase epsilon. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:2549-58. [PMID: 17669357 DOI: 10.1016/j.bbamem.2007.06.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 05/26/2007] [Accepted: 06/12/2007] [Indexed: 11/23/2022]
Abstract
Diacylglycerol kinase epsilon (DGKepsilon) is unique among mammalian DGK isoforms in having a segment of hydrophobic amino acids as a putative membrane anchor. To model the conformation, and stoichiometry of this segment in membrane-mimetic environments, we have prepared a peptide corresponding to this hydrophobic segment of DGKepsilon of sequence KKKKLILWTLCSVLLPVFITFWKKKKK-NH(2). Flanking Lys residues mimic the natural setting of this peptide in DGKepsilon, while facilitating peptide synthesis and characterization. Circular dichroism and fluorescence spectroscopic analysis demonstrated that the peptide has increased helical content and significant blue shifts in the presence of anionic--but not zwitterionic--bilayer membranes. When labeled with fluorophores that can undergo fluorescence resonance energy transfer, the peptide was found to dimerize--a result also observed from migration rates on SDS-PAGE gels under both reducing and non-reducing disulfide bridge conditions. The peptide was shown to preferentially interact with cholesterol in lipid films comprised of homogeneous mixtures of cholesterol and phosphatidylcholine, yet the presence of cholesterol in hydrated vesicle bilayers decreases its helical content. The peptide was also able to inhibit the activity of DGKepsilon protein in vitro. Our overall findings suggest that the peptide ultimately cannot leave the bulk water for attachment/insertion into the outer leaflet of an erythrocyte-like bilayer, yet its core sequence is sufficiently hydrophobic to insert into membrane core regions when membrane attachment is promoted by electrostatic attraction to anionic lipid head groups of the inner leaflet of an erythrocyte-like bilayer.
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Affiliation(s)
- Evgenia Glukhov
- Division of Molecular Structure & Function, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
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29
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Horton MR, Rädler J, Gast AP. Phase behavior and the partitioning of caveolin-1 scaffolding domain peptides in model lipid bilayers. J Colloid Interface Sci 2006; 304:67-76. [PMID: 17022989 DOI: 10.1016/j.jcis.2006.08.057] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Revised: 08/25/2006] [Accepted: 08/28/2006] [Indexed: 02/05/2023]
Abstract
The membrane binding and model lipid raft interaction of synthetic peptides derived from the caveolin scaffolding domain (CSD) of the protein caveolin-1 have been investigated. CSD peptides bind preferentially to liquid-disordered domains in model lipid bilayers composed of cholesterol and an equimolar ratio of dioleoylphosphatidylcholine (DOPC) and brain sphingomyelin. Three caveolin-1 peptides were studied: the scaffolding domain (residues 83-101), a water-insoluble construct containing residues 89-101, and a water-soluble construct containing residues 89-101. Confocal and fluorescence microscopy investigation shows that the caveolin-1 peptides bind to the more fluid cholesterol-poor phase. The binding of the water-soluble peptide to lipid bilayers was measured using fluorescence correlation spectroscopy (FCS). We measured molar partition coefficients of 10(4) M(-1) between the soluble peptide and phase-separated lipid bilayers and 10(3) M(-1) between the soluble peptide and bilayers with a single liquid phase. Partial phase diagrams for our phase-separating lipid mixture with added caveolin-1 peptides were measured using fluorescence microscopy. The water-soluble peptide did not change the phase morphology or the miscibility transition in giant unilamellar vesicles (GUVs); however, the water-insoluble and full-length CSD peptides lowered the liquid-liquid melting temperature.
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Affiliation(s)
- Margaret R Horton
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
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30
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Epand RF, Thomas A, Brasseur R, Vishwanathan SA, Hunter E, Epand RM. Juxtamembrane protein segments that contribute to recruitment of cholesterol into domains. Biochemistry 2006; 45:6105-14. [PMID: 16681383 PMCID: PMC2515711 DOI: 10.1021/bi060245+] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We investigated the properties of several peptides with sequences related to LWYIK, a segment found in the gp41 protein of HIV and believed to play a role in sequestering this protein to a cholesterol-rich domain in the membrane. This segment fulfills the requirements to be classified as a CRAC motif that has been suggested to predict those proteins that will partition into cholesterol-rich regions of the membrane. All of the peptides were studied with the terminal amino and carboxyl groups blocked, i.e., as N-acetyl-peptide-amides. Effects of cholesterol on the intensity of W emission generally parallel DSC evidence of sequestration of cholesterol. Modeling studies indicate that all of these peptides tend to partition with their mass center at the membrane interface at the level of the hydroxyl of cholesterol. Interaction with cholesterol is dual: van der Waals interactions between mainly hydrophobic surfaces and electrostatic stabilization of the cholesterol OH group. Thus, both experiments and modeling studies indicate that the preference of CRAC motifs for cholesterol-rich domains might be related to a membrane interfacial preference of the motif, to a capacity to wrap and block the cholesterol polar OH group by H-bond interactions, and to a capacity for peptide aromatic side chains to stack with cholesterol. These results were supported by studies of single mutations in the gp41 protein of HIV-1, in which L(679) is replaced with I. Despite the similarity of the properties of these amino acid residues, this single substitution resulted in a marked attenuation of the ability of JC53-BL HeLa-based HIV-1 indicator cells to form syncytia.
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Affiliation(s)
- Raquel F Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada
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31
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Zhang W, Sato T, Smith SO. NMR spectroscopy of basic/aromatic amino acid clusters in membrane proteins. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2006. [PMCID: PMC7112282 DOI: 10.1016/j.pnmrs.2006.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Affiliation(s)
| | | | - Steven O. Smith
- Corresponding author. Tel.: +1 631 632 1210; fax: +1 631 632 8575.
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32
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Spurlin TA, Gewirth AA. Poly-L-lysine-induced morphology changes in mixed anionic/zwitterionic and neat zwitterionic-supported phospholipid bilayers. Biophys J 2006; 91:2919-27. [PMID: 16877517 PMCID: PMC1578480 DOI: 10.1529/biophysj.106.082479] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Poly-L-lysine-induced morphological changes in liquid phase supported bilayers consisting of mixed anionic/zwitterionic and neat zwitterionic headgroup phospholipids were studied with atomic force microscopy and epifluorescence microscopy. Results obtained from these studies indicate that poly-L-lysine can induce domains, defects, and aggregate structures on both mixed bilayers and strictly zwitterionic bilayers. The structures formed on liquid phase supported bilayers were observed to be immobile from a timescale of 50 ms to several minutes. We propose that poly-L-lysine of sufficient length interacts with the mica substrate and phospholipids to create the stationary structures noted.
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Affiliation(s)
- Tighe A Spurlin
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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33
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Epand RM. Detecting the presence of membrane domains using DSC. Biophys Chem 2006; 126:197-200. [PMID: 16730877 DOI: 10.1016/j.bpc.2006.05.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Accepted: 05/10/2006] [Indexed: 11/24/2022]
Abstract
Both biological and model liposomal membranes have unequal distribution of molecular components in the plane of the membrane. There is increasing interest to determine the composition and properties of membrane domains enriched with specific molecular components. Several methodologies have been applied to study this. Each has its own advantages and provides a particular kind of information. In the present article, we will focus on the application of differential scanning calorimetry to the determination of the distribution of molecules into membrane domains with particular emphasis on protein and peptide-induced domain formation.
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Affiliation(s)
- Richard M Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University Health Sciences Centre, Hamilton, ON, Canada L8N 3Z5.
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34
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Sperotto MM, May S, Baumgaertner A. Modelling of proteins in membranes. Chem Phys Lipids 2006; 141:2-29. [PMID: 16620797 DOI: 10.1016/j.chemphyslip.2006.02.024] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Accepted: 02/20/2006] [Indexed: 11/17/2022]
Abstract
This review describes some recent theories and simulations of mesoscopic and microscopic models of lipid membranes with embedded or attached proteins. We summarize results supporting our understanding of phenomena for which the activities of proteins in membranes are expected to be significantly affected by the lipid environment. Theoretical predictions are pointed out, and compared to experimental findings, if available. Among others, the following phenomena are discussed: interactions of interfacially adsorbed peptides, pore-forming amphipathic peptides, adsorption of charged proteins onto oppositely charged lipid membranes, lipid-induced tilting of proteins embedded in lipid bilayers, protein-induced bilayer deformations, protein insertion and assembly, and lipid-controlled functioning of membrane proteins.
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35
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Epand RM. Cholesterol and the interaction of proteins with membrane domains. Prog Lipid Res 2006; 45:279-94. [PMID: 16574236 DOI: 10.1016/j.plipres.2006.02.001] [Citation(s) in RCA: 232] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Revised: 02/02/2006] [Accepted: 02/20/2006] [Indexed: 12/18/2022]
Abstract
Cholesterol is not uniformly distributed in biological membranes. One of the factors influencing the formation of cholesterol-rich domains in membranes is the unequal lateral distribution of proteins in membranes. Certain proteins are found in cholesterol-rich domains. In some of these cases, it is as a consequence of the proteins interacting directly with cholesterol. There are several structural features of a protein that result in the protein preferentially associating with cholesterol-rich domains. One of the best documented of these is certain types of lipidations. In addition, however, there are segments of a protein that can preferentially sequester cholesterol. We discuss two examples of these cholesterol-recognition elements: the cholesterol recognition/interaction amino acid consensus (CRAC) domain and the sterol-sensing domain (SSD). The requirements for a CRAC motif are quite flexible and predict that a large number of sequences could recognize cholesterol. There are, however, certain proteins that are known to interact with cholesterol-rich domains of cell membranes that have CRAC motifs, and synthetic peptides corresponding to these segments also promote the formation of cholesterol-rich domains. Modeling studies have provided a rationale for certain requirements of the CRAC motif. The SSD is a larger protein segment comprising five transmembrane domains. The amino acid sequence YIYF is found in several SSD and in certain other proteins for which there is evidence that they interact with cholesterol-rich domains. The CRAC sequences as well as YIYF are generally found adjacent to a transmembrane helical segment. These regions appear to have a strong influence of the localization of certain proteins into domains in biological membranes. In addition to the SSD, there is also a domain found in soluble proteins, the START domain, that binds lipids. Certain proteins with START domains specifically bind cholesterol and are believed to function in intracellular cholesterol transport. One of these proteins is StAR-D1, that also has a mitochondrial targeting sequence and plays an important role in delivering cholesterol to the mitochondria of steroidogenic cells.
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Affiliation(s)
- Richard M Epand
- Department of Biochemistry and Biomedical Sciences, Health Sciences Centre, McMaster University, 1200 Main Street, Hamilton, Ont., Canada L8N 3Z5.
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36
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Epand RM, Rychnovsky SD, Belani JD, Epand RF. Role of chirality in peptide-induced formation of cholesterol-rich domains. Biochem J 2006; 390:541-8. [PMID: 15929726 PMCID: PMC1198934 DOI: 10.1042/bj20050649] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The chiral specificity of the interactions of peptides that induce the formation of cholesterol-rich domains has not been extensively investigated. Both the peptide and most lipids are chiral, so there is a possibility that interactions between peptide and lipid could require chiral recognition. On the other hand, in our models with small peptides, the extent of folding of the peptide to form a specific binding pocket is limited. We have determined that replacing cholesterol with its enantiomer, ent-cholesterol, alters the modulation of lipid organization by peptides. The phase-transition properties of SOPC (1-stearoyl-2-oleoylphosphatidylcholine):cholesterol [in a 6:4 ratio with 0.2 mol% PtdIns(4,5)P2] are not significantly altered when ent-cholesterol replaces cholesterol. However, in the presence of 10 mol% of a 19-amino-acid, N-terminally myristoylated fragment (myristoyl-GGKLSKKKKGYNVNDEKAK-amide) of the protein NAP-22 (neuronal axonal membrane protein), the lipid mixture containing cholesterol undergoes separation into cholesterol-rich and cholesterol-depleted domains. This does not occur when ent-cholesterol replaces cholesterol. In another example, when N-acetyl-Leu-Trp-Tyr-Ile-Lys-amide (N-acetyl-LWYIK-amide) is added to SOPC:cholesterol (7:3 ratio), there is a marked increase in the transition enthalpy of the phospholipid, indicating separation of a cholesterol-depleted domain of SOPC. This phenomenon completely disappears when ent-cholesterol replaces cholesterol. The all-D-isomer of N-acetyl-LWYIK-amide also induces the formation of cholesterol-rich domains with natural cholesterol, but does so to a lesser extent with ent-cholesterol. Thus specific peptide chirality is not required for interaction with cholesterol-containing membranes. However, a specific chirality of membrane lipids is required for peptide-induced formation of cholesterol-rich domains.
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Affiliation(s)
- Richard M Epand
- Department of Biochemistry, McMaster University, 1200 Main Street West, Hamilton, Ontario, Canada L8N 3Z5.
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Bhat RA, Panstruga R. Lipid rafts in plants. PLANTA 2005; 223:5-19. [PMID: 16136329 DOI: 10.1007/s00425-005-0096-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Accepted: 07/20/2005] [Indexed: 05/04/2023]
Abstract
About two decades ago a provocative hypothesis evolved suggesting that the plasma membrane (PM) of mammalian and probably other eukaryotic cells constitutes a mosaic of patches comprising particular molecular compositions. These scattered lipid bilayer microdomains are supposedly enriched in sterols as well as sphingolipids and depleted in unsaturated phospholipids. In addition, the PM microdomains are proposed to host glycosyl-phosphatidylinositol-anchored polypeptides and a subset of integral and peripheral cell surface proteins while excluding others. Though the actual in vivo existence of such "lipid rafts" remains controversial, a range of fundamental biological functions has been put forward for these PM microenvironments. A variety of recent studies provide preliminary evidence that lipid rafts may also occur in plant cells.
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Affiliation(s)
- Riyaz A Bhat
- Max-Planck Institute for Plant Breeding Research, Carl-von-Linnè-Weg 10, 50829 Köln, Germany
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Maggio B, Rosetti CM, Borioli GA, Fanani ML, Del Boca M. Protein-mediated surface structuring in biomembranes. Braz J Med Biol Res 2005; 38:1735-48. [PMID: 16302088 DOI: 10.1590/s0100-879x2005001200002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The lipids and proteins of biomembranes exhibit highly dissimilar conformations, geometrical shapes, amphipathicity, and thermodynamic properties which constrain their two-dimensional molecular packing, electrostatics, and interaction preferences. This causes inevitable development of large local tensions that frequently relax into phase or compositional immiscibility along lateral and transverse planes of the membrane. On the other hand, these effects constitute the very codes that mediate molecular and structural changes determining and controlling the possibilities for enzymatic activity, apposition and recombination in biomembranes. The presence of proteins constitutes a major perturbing factor for the membrane sculpturing both in terms of its surface topography and dynamics. We will focus on some results from our group within this context and summarize some recent evidence for the active involvement of extrinsic (myelin basic protein), integral (Folch-Lees proteolipid protein) and amphitropic (c-Fos and c-Jun) proteins, as well as a membrane-active amphitropic phosphohydrolytic enzyme (neutral sphingomyelinase), in the process of lateral segregation and dynamics of phase domains, sculpturing of the surface topography, and the bi-directional modulation of the membrane biochemical reactivity.
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Affiliation(s)
- B Maggio
- Departamento de Química Biológica, CIQUIBIC, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina.
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Barakat S, Gayet L, Dayan G, Labialle S, Lazar A, Oleinikov V, Coleman A, Baggetto L. Multidrug-resistant cancer cells contain two populations of P-glycoprotein with differently stimulated P-gp ATPase activities: evidence from atomic force microscopy and biochemical analysis. Biochem J 2005; 388:563-71. [PMID: 15693753 PMCID: PMC1138964 DOI: 10.1042/bj20041999] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Considerable interest exists about the localization of P-gp (P-glycoprotein) in DRMs (detergent-resistant membranes) of multidrug resistant cancer cells, in particular concerning the potential modulating role of the closely related lipids and proteins on P-gp activity. Our observation of the opposite effect of verapamil on P-gp ATPase activity from DRM and solubilized-membrane fractions of CEM-resistant leukaemia cells, and results from Langmuir experiments on membrane monolayers from resistant CEM cells, strongly suggest that two functional populations of P-gp exist. The first is located in DRM regions: it displays its optimal P-gp ATPase activity, which is almost completely inhibited by orthovanadate and activated by verapamil. The second is located elsewhere in the membrane; it displays a lower P-gp ATPase activity that is less sensitive to orthovanadate and is inhibited by verapamil. A 40% cholesterol depletion of DRM caused the loss of 52% of the P-gp ATPase activity. Cholesterol repletion allowed recovery of the initial P-gp ATPase activity. In contrast, in the solubilized-membrane-containing fractions, cholesterol depletion and repletion had no effect on the P-gp ATPase activity whereas up to 100% saturation with cholesterol induced a 58% increased P-gp ATPase activity, while no significant modification was observed for the DRM-enriched fraction. DRMs were analysed by atomic force microscopy: 40-60% cholesterol depletion was necessary to remove P-gp from DRMs. In conclusion, P-gp in DRMs appears to contain closely surrounding cholesterol that can stimulate P-gp ATPase activity to its optimal value, whereas cholesterol in the second population seems deprived of this function.
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Affiliation(s)
- Stéphane Barakat
- *Thérapie transcriptionnelle des cellules cancéreuses, IBCP - UMR 5086 CNRS UCBL, 7 Passage du Vercors, 69367 Lyon cedex 07, France
| | - Landry Gayet
- *Thérapie transcriptionnelle des cellules cancéreuses, IBCP - UMR 5086 CNRS UCBL, 7 Passage du Vercors, 69367 Lyon cedex 07, France
| | - Guila Dayan
- *Thérapie transcriptionnelle des cellules cancéreuses, IBCP - UMR 5086 CNRS UCBL, 7 Passage du Vercors, 69367 Lyon cedex 07, France
| | - Stéphane Labialle
- †McGill University, Royal Victoria Hospital, F3.32, 687 Pine avenue West, Montreal, QC, Canada H3A 1A1
| | - Adina Lazar
- ‡Assemblages moléculaires d'intérêt biologique, IBCP - UMR 5086 CNRS UCBL, 7 Passage du Vercors, 69367 Lyon cedex 07, France
| | - Vladimir Oleinikov
- §Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, Moscow B-437, GSP 117997, Russia
| | - Anthony W. Coleman
- ‡Assemblages moléculaires d'intérêt biologique, IBCP - UMR 5086 CNRS UCBL, 7 Passage du Vercors, 69367 Lyon cedex 07, France
| | - Loris G. Baggetto
- *Thérapie transcriptionnelle des cellules cancéreuses, IBCP - UMR 5086 CNRS UCBL, 7 Passage du Vercors, 69367 Lyon cedex 07, France
- To whom correspondence should be addressed (email )
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Abstract
Current models for cellular plasma membranes focus on spatial heterogeneity and how this heterogeneity relates to cell function. In particular, putative lipid raft membrane domains have been postulated to exist based in large part on the results that a significant fraction of the membrane is detergent insoluble and that molecules facilitating key membrane processes like signal transduction are often found in the detergent-resistant membrane fraction. Yet, the in vivo existence of lipid rafts remains extremely controversial because, despite being sought for more than a decade, evidence for their presence in intact cell membranes is inconclusive. In this review, a variety of experimental techniques that have been or might be used to look for lipid microdomains in intact cell membranes are described. Experimental results are highlighted and the strengths and limitations of different techniques for microdomain identification and characterization are assessed.
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Affiliation(s)
- B Christoffer Lagerholm
- Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
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Epand RM, Sayer BG, Epand RF. Caveolin scaffolding region and cholesterol-rich domains in membranes. J Mol Biol 2005; 345:339-50. [PMID: 15571726 DOI: 10.1016/j.jmb.2004.10.064] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2004] [Revised: 10/20/2004] [Accepted: 10/20/2004] [Indexed: 12/30/2022]
Abstract
A protein that constitutes a good marker for a type of cholesterol-rich domain in biological membranes is caveolin. A segment of this protein has a sequence that corresponds to a cholesterol recognition/interaction amino acid consensus (CRAC) motif; this motif has been suggested to cause the incorporation of proteins into cholesterol-rich domains. We have studied the interaction of two peptides containing the CRAC motif of caveolin-1 by differential scanning calorimetry, fluorescence, circular dichroism and magic angle spinning NMR. These peptides promote the segregation of cholesterol into domains from mixtures of the sterol with phosphatidylcholine, as shown by depletion of cholesterol from a portion of the membrane and enrichment of cholesterol in another domain. Cholesterol passes its solubility limit in the cholesterol-rich domain, resulting in the formation of cholesterol crystallites, suggesting that not all of the cholesterol recruited to this domain is bound to the peptide. NMR studies show that the peptides insert somewhat more deeply into membranes when cholesterol is present, but their strongest interaction takes place with the interfacial region of the membrane. We conclude that the peptides we studied containing CRAC sequences are more effective in promoting the formation of cholesterol-rich domains than are shorter peptides of this region of caveolin, which although they contain several aromatic amino acids, they have no CRAC motif. The presence or absence of a CRAC motif, however, is not a sufficient criterion to determine the extent to which a protein will promote the segregation of cholesterol in membranes.
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Affiliation(s)
- Richard M Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada, L8N 3Z5.
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Epand RM, Epand RF, Sayer BG, Datta G, Chaddha M, Anantharamaiah GM. Two Homologous Apolipoprotein AI Mimetic Peptides. J Biol Chem 2004; 279:51404-14. [PMID: 15358763 DOI: 10.1074/jbc.m408581200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two related 18-amino acid, class A, amphipathic helical peptides termed 3F-2 and 3F14 were chosen for this study. Although they have identical amino acid compositions and many similar biophysical properties, 3F-2 is more potent than 3F14 as an apolipoprotein AI mimetic peptide. The two peptides exhibit similar gross conformational properties, forming structures of high helical content on a membrane surface. However, the thermal denaturation transition of 3F-2 is more cooperative, suggesting a higher degree of oligomerization on the membrane. Both 3F-2 and 3F14 promote the segregation of cholesterol in membranes containing phosphatidylcholine and cholesterol, but 3F-2 exhibits a greater selectivity for partitioning into cholesterol-depleted regions of the membrane. Magic angle spinning/NMR studies indicate that the aromatic residues of 3F-2 are stacked in the presence of lipid. The aromatic side chains of this peptide also penetrate more deeply into membranes of phosphatidylcholine with cholesterol compared with 3F14. Using the fluorescent probe, 1,3-dipyrenylpropane, we monitored the properties of the lipid hydrocarbon environment. 3F-2 had a greater effect in altering the properties of the hydrocarbon region of the membrane. The results are consistent with our proposed model of the effect of peptide shape on the nature of the difference in peptide insertion into the bilayer.
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Affiliation(s)
- Richard M Epand
- Departments of Biochemistry and Biomedical Sciences and Chemistry, McMaster University, Hamilton, Ontario L8N 3Z5, Canada.
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