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Inimitable Impacts of Ceramides on Lipid Rafts Formed in Artificial and Natural Cell Membranes. MEMBRANES 2022; 12:membranes12080727. [PMID: 35893445 PMCID: PMC9330320 DOI: 10.3390/membranes12080727] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/19/2022] [Accepted: 07/20/2022] [Indexed: 02/02/2023]
Abstract
Ceramide is the simplest precursor of sphingolipids and is involved in a variety of biological functions ranging from apoptosis to the immune responses. Although ceramide is a minor constituent of plasma membranes, it drastically increases upon cellular stimulation. However, the mechanistic link between ceramide generation and signal transduction remains unknown. To address this issue, the effect of ceramide on phospholipid membranes has been examined in numerous studies. One of the most remarkable findings of these studies is that ceramide induces the coalescence of membrane domains termed lipid rafts. Thus, it has been hypothesised that ceramide exerts its biological activity through the structural alteration of lipid rafts. In the present article, we first discuss the characteristic hydrogen bond functionality of ceramides. Then, we showed the impact of ceramide on the structures of artificial and cell membranes, including the coalescence of the pre-existing lipid raft into a large patch called a signal platform. Moreover, we proposed a possible structure of the signal platform, in which sphingomyelin/cholesterol-rich and sphingomyelin/ceramide-rich domains coexist. This structure is considered to be beneficial because membrane proteins and their inhibitors are separately compartmentalised in those domains. Considering the fact that ceramide/cholesterol content regulates the miscibility of those two domains in model membranes, the association and dissociation of membrane proteins and their inhibitors might be controlled by the contents of ceramide and cholesterol in the signal platform.
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Lee H, Choi SQ. Sphingomyelinase-Mediated Multitimescale Clustering of Ganglioside GM1 in Heterogeneous Lipid Membranes. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2101766. [PMID: 34473415 PMCID: PMC8529493 DOI: 10.1002/advs.202101766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 07/19/2021] [Indexed: 05/05/2023]
Abstract
Several signaling processes in the plasma membrane are intensified by ceramides that are formed by sphingomyelinase-mediated hydrolysis of sphingomyelin. These ceramides trigger clustering of signaling-related biomolecules, but how they concentrate such biomolecules remains unclear. Here, the spatiotemporal localization of ganglioside GM1, a glycolipid receptor involved in signaling, during sphingomyelinase-mediated hydrolysis is described. Real-time visualization of the dynamic remodeling of the heterogeneous lipid membrane that occurs due to sphingomyelinase action is used to examine GM1 clustering, and unexpectedly, it is found that it is more complex than previously thought. Specifically, lipid membranes generate two distinct types of condensed GM1: 1) rapidly formed but short-lived GM1 clusters that are formed in ceramide-rich domains nucleated from the liquid-disordered phase; and 2) late-onset yet long-lasting, high-density GM1 clusters that are formed in the liquid-ordered phase. These findings suggest that multiple pathways exist in a plasma membrane to synergistically facilitate the rapid amplification and persistence of signals.
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Affiliation(s)
- Hyun‐Ro Lee
- Department of Chemical and Biomolecular EngineeringKorea Advanced Institute of Science and Technology (KAIST)Daejeon34141Republic of Korea
| | - Siyoung Q. Choi
- Department of Chemical and Biomolecular EngineeringKorea Advanced Institute of Science and Technology (KAIST)Daejeon34141Republic of Korea
- KAIST Institute for the NanoCenturyKorea Advanced Institute of Science and Technology (KAIST)Daejeon34141Republic of Korea
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3
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Metabolic Depletion of Sphingolipids Does Not Alter Cell Cycle Progression in Chinese Hamster Ovary Cells. J Membr Biol 2021; 255:1-12. [PMID: 34392379 DOI: 10.1007/s00232-021-00198-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 08/02/2021] [Indexed: 10/20/2022]
Abstract
The cell cycle is a sequential multi-step process essential for growth and proliferation of cells comprising multicellular organisms. Although a number of proteins are known to modulate the cell cycle, the role of lipids in regulation of cell cycle is still emerging. In our previous work, we monitored the role of cholesterol in cell cycle progression in CHO-K1 cells. Since sphingolipids enjoy a functionally synergistic relationship with membrane cholesterol, in this work, we explored whether sphingolipids could modulate the eukaryotic cell cycle using CHO-K1 cells. Sphingolipids are essential components of eukaryotic cell membranes and are involved in a number of important cellular functions. To comprehensively monitor the role of sphingolipids on cell cycle progression, we carried out metabolic depletion of sphingolipids in CHO-K1 cells using inhibitors (fumonisin B1, myriocin, and PDMP) that block specific steps of the sphingolipid biosynthetic pathway and examined their effect on individual cell cycle phases. Our results show that metabolic inhibitors led to significant reduction in specific sphingolipids, yet such inhibition in sphingolipid biosynthesis did not show any effect on cell cycle progression in CHO-K1 cells. We speculate that any role of sphingolipids on cell cycle progression could be context and cell-type dependent, and cancer cells could be a better choice for monitoring such regulation, since sphingolipids are differentially modulated in these cells.
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Changes in Membrane Ceramide Pools in Rat Soleus Muscle in Response to Short-Term Disuse. Int J Mol Sci 2019; 20:ijms20194860. [PMID: 31574943 PMCID: PMC6801848 DOI: 10.3390/ijms20194860] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 09/27/2019] [Accepted: 09/28/2019] [Indexed: 12/17/2022] Open
Abstract
Lipid raft disruption is an early event during skeletal muscle unloading. Ceramide (Cer) serves as a signaling lipid that can contribute to lipid raft disturbance and muscle atrophy. Using biochemical and fluorescent approaches, the distribution of Cer and related molecules in the rat soleus muscle subjected to 12 h of hindlimb suspension (HS) was studied. HS led to upregulation of TNFα receptor 1 (TNFR1), Cer-producing enzymes, and acid and neutral sphingomyelinase (SMase) in detergent-resistant membranes (lipid rafts), which was accompanied by an increase in Cer and a decrease in sphingomyelin in this membrane fraction. Fluorescent labeling indicated increased Cer in the sarcoplasm as well as the junctional (synaptic) and extrajunctional compartments of the suspended muscles. Also, a loss of membrane asymmetry (a hallmark of membrane disturbance) was induced by HS. Pretreatment with clomipramine, a functional inhibitor of acid SMase, counteracted HS-mediated changes in the Cer/sphingomyelin ratio and acid SMase abundance as well as suppressed Cer accumulation in the intracellular membranes of junctional and extrajunctional regions. However, the elevation of plasma membrane Cer and disturbance of the membrane asymmetry were suppressed only in the junctional compartment. We suggest that acute HS leads to TNFR1 and SMase upregulation in the lipid raft fraction and deposition of Cer throughout the sarcolemma and intracellularly. Clomipramine-mediated downregulation of acid SMase can suppress Cer accumulation in all compartments, excluding the extrajunctional plasma membrane.
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Almeida C, De Wreede A, Lamazière A, Ayala-Sanmartin J. Cholesterol-pyrene as a probe for cholesterol distribution on ordered and disordered membranes: Determination of spectral wavelengths. PLoS One 2018; 13:e0201373. [PMID: 30096186 PMCID: PMC6086420 DOI: 10.1371/journal.pone.0201373] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/13/2018] [Indexed: 12/12/2022] Open
Abstract
Biological membranes contain a large variety of lipids species compartmentalized in different domains heterogeneous in size, composition and dynamics. Cholesterol induces membrane ordered domains thanks to its affinity for saturated lipids. Membrane domains had been studied with fluorescent probes either linked to phospholipids and proteins or as individual fluorophore. However, no efficient formulation of a cholesterol probe has been available so far. Herein, we described a cholesterol-pyrene probe behaviour in heterogeneous membranes. We characterised the pyrene fluorescence spectra in liquid-ordered (Lo) and liquid-disordered (Ld) membranes. Using statistical multivariate analysis, we found out the most appropriate wavelengths for membrane domains studies. 373 nm and 379 nm were the most discriminant wavelengths to follow the liquid-ordered and the liquid-disordered environments. Cholesterol clustering behaviour was quantified by the modulation of the cholesterol-pyrene excimers peak (474 nm). In liquid-ordered membranes at low temperature, cholesterol-pyrene was found as multimers and as monomers. At high temperature, the liquid-ordered status of the membrane decreases and cholesterol-pyrene tends to cluster. In liquid-disordered membranes, cholesterol-pyrene was present mostly as monomers and the small quantity of excimers increased with temperature. Cholesterol-pyrene was used to test the ceramide effect on membranes, and presented a behaviour in agreement with the cholesterol behaviour reported in the literature. Overall, the presented data show that cholesterol-pyrene is an efficient sensor to study liquid ordered and liquid disordered organisation in membranes.
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Affiliation(s)
- Claudia Almeida
- CNRS, Sorbonne Université, École normale supérieure, PSL University, INSERM, APHP,Hôpital Saint-Antoine, Laboratoire des biomolécules, LBM, Paris, France
| | - Anaëlle De Wreede
- CNRS, Sorbonne Université, École normale supérieure, PSL University, INSERM, APHP,Hôpital Saint-Antoine, Laboratoire des biomolécules, LBM, Paris, France
| | - Antonin Lamazière
- CNRS, Sorbonne Université, École normale supérieure, PSL University, INSERM, APHP,Hôpital Saint-Antoine, Laboratoire des biomolécules, LBM, Paris, France
| | - Jesus Ayala-Sanmartin
- CNRS, Sorbonne Université, École normale supérieure, PSL University, INSERM, APHP,Hôpital Saint-Antoine, Laboratoire des biomolécules, LBM, Paris, France
- * E-mail:
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6
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Abstract
Ceramides are sphingolipids containing a sphingosine or a related base, to which a fatty acid is linked through an amide bond. When incorporated into a lipid bilayer, ceramides exhibit a number of properties not shared by almost any other membrane lipid: Ceramides ( a) are extremely hydrophobic and thus cannot exist in suspension in aqueous media; ( b) increase the molecular order (rigidity) of phospholipids in membranes; ( c) give rise to lateral phase separation and domain formation in phospholipid bilayers; ( d) possess a marked intrinsic negative curvature that facilitates formation of inverted hexagonal phases; ( e) make bilayers and cell membranes permeable to small and large (i.e., protein-size) solutes; and ( f) promote transmembrane (flip-flop) lipid motion. Unfortunately, there is hardly any link between the physical studies reviewed here and the mass of biological and clinical studies on the effects of ceramides in health and disease.
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Affiliation(s)
- Alicia Alonso
- Instituto Biofisika [University of the Basque Country and Spanish National Research Council (CSIC)], 48940 Leioa, Spain
- Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa, Spain;,
| | - Félix M. Goñi
- Instituto Biofisika [University of the Basque Country and Spanish National Research Council (CSIC)], 48940 Leioa, Spain
- Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa, Spain;,
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Brewer J, Thoke HS, Stock RP, Bagatolli LA. Enzymatic studies on planar supported membranes using a widefield fluorescence LAURDAN Generalized Polarization imaging approach. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:888-895. [DOI: 10.1016/j.bbamem.2017.01.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 01/15/2017] [Accepted: 01/19/2017] [Indexed: 12/01/2022]
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Shirey CM, Ward KE, Stahelin RV. Investigation of the biophysical properties of a fluorescently modified ceramide-1-phosphate. Chem Phys Lipids 2016; 200:32-41. [PMID: 27318040 DOI: 10.1016/j.chemphyslip.2016.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 06/14/2016] [Indexed: 12/11/2022]
Abstract
Ceramide-1-phosphate (C1P) is an important signaling sphingolipid and a metabolite of ceramide. C1P contains an anionic phosphomonoester head group and has been shown to regulate physiological and pathophysiological processes such as cell proliferation, inflammation, apoptosis, phagocytosis, and macrophage chemotaxis. Despite this mechanistic information on its role in intra- and intercellular communication, little information is available on the biophysical properties of C1P in biological membranes and how it interacts with effector proteins. Fluorescently labeled lipids have been a useful tool to understand the membrane behavior properties of lipids such as phosphatidylserine, cholesterol, and some phosphoinositides. However, to the best of our knowledge, fluorescently labeled C1P hasn't been implemented to investigate its ability to serve as a mimetic of endogenous C1P in cells or untagged C1P in in vitro experiments. Cellular and in vitro assays demonstrate TopFluor-C1P harbors a fluorescent group that is fully buried in the hydrocarbon core and fluoresces across the spectrum of physiological pH values. Moreover, TopFluor-C1P didn't affect cellular toxicity at concentrations employed, was as effective as unlabeled C1P in recruiting an established protein effector to intracellular membranes, and its subcellular localization recapitulated what is known for endogenous C1P. Notably, the diffusion coefficient of TopFluor-C1P was slower than that of TopFluor-phosphatidylserine or TopFluor-cholesterol in the plasma membrane and similar to that of other fluorescently labeled sphingolipids including ceramide and sphingomyelin. These studies demonstrate that TopFluor-C1P should be a reliable mimetic of C1P to study C1P membrane biophysical properties and C1P interactions with proteins.
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Affiliation(s)
- Carolyn M Shirey
- Department of Chemistry and Biochemistry and the Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Katherine E Ward
- Department of Chemistry and Biochemistry and the Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Robert V Stahelin
- Department of Chemistry and Biochemistry and the Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556, United States; Department of Biochemistry and Molecular Biology, Indiana University School of Medicine-South Bend, South Bend, IN 46617, United States.
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9
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García-Arribas AB, Alonso A, Goñi FM. Cholesterol interactions with ceramide and sphingomyelin. Chem Phys Lipids 2016; 199:26-34. [PMID: 27132117 DOI: 10.1016/j.chemphyslip.2016.04.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 04/05/2016] [Accepted: 04/06/2016] [Indexed: 01/10/2023]
Abstract
Sphingolipids contain in their polar heads chemical groups allowing them to establish a complex network of H-bonds (through different OH and NHgroups) with other lipids in the bilayer. In the recent years the specific interaction of sphingomyelin (SM) with cholesterol (Chol) has been examined, largely in the context of the "lipid raft" hypothesis. Formation of SM-Ceramide (Cer) complexes, proposed to exist in cell membranes in response to stress, has also been described. More recently, a delicate balance of phase formation and transformation in ternary mixtures of SM, Chol and Cer, with mutual displacement of Chol and Cer from their interaction with SM is considered to exist. In addition, data demonstrating direct Chol-Cer interaction are becoming available.
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Affiliation(s)
- Aritz B García-Arribas
- Biofisika Institute (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, 48080 Bilbao, Spain
| | - Alicia Alonso
- Biofisika Institute (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, 48080 Bilbao, Spain
| | - Felix M Goñi
- Biofisika Institute (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, 48080 Bilbao, Spain.
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10
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Saslowsky DE, Thiagarajah JR, McCormick BA, Lee JC, Lencer WI. Microbial sphingomyelinase induces RhoA-mediated reorganization of the apical brush border membrane and is protective against invasion. Mol Biol Cell 2016; 27:1120-30. [PMID: 26864627 PMCID: PMC4814219 DOI: 10.1091/mbc.e15-05-0293] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 02/01/2016] [Indexed: 12/19/2022] Open
Abstract
Both commensal and pathogenic microbes that colonize the GI tract can synthesize and secrete spingomyelinase enzymes that cleave membrane sphingomyelin, leaving the ceramide component intact in the cell membrane. This study examines how this reaction affects the structure and function of host enterocytes and mucosal defense. The apical brush border membrane (BBM) of intestinal epithelial cells forms a highly structured and dynamic environmental interface that serves to regulate cellular physiology and block invasion by intestinal microbes and their products. How the BBM dynamically responds to pathogenic and commensal bacterial signals can define intestinal homeostasis and immune function. We previously found that in model intestinal epithelium, the conversion of apical membrane sphingomyelin to ceramide by exogenous bacterial sphingomyelinase (SMase) protected against the endocytosis and toxicity of cholera toxin. Here we elucidate a mechanism of action by showing that SMase induces a dramatic, reversible, RhoA-dependent alteration of the apical cortical F-actin network. Accumulation of apical membrane ceramide is necessary and sufficient to induce the actin phenotype, and this coincides with altered membrane structure and augmented innate immune function as evidenced by resistance to invasion by Salmonella.
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Affiliation(s)
- David E Saslowsky
- Division of Gastroenterology and Nutrition, Boston Children's Hospital, Boston, MA 02115 Harvard Digestive Diseases Center, Boston Children's Hospital, Boston, MA 02115 Harvard Medical School, Boston, MA 02115
| | - Jay R Thiagarajah
- Division of Gastroenterology and Nutrition, Boston Children's Hospital, Boston, MA 02115 Harvard Digestive Diseases Center, Boston Children's Hospital, Boston, MA 02115 Harvard Medical School, Boston, MA 02115
| | - Beth A McCormick
- Harvard Digestive Diseases Center, Boston Children's Hospital, Boston, MA 02115 Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01655
| | - Jean C Lee
- Harvard Medical School, Boston, MA 02115 Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115
| | - Wayne I Lencer
- Division of Gastroenterology and Nutrition, Boston Children's Hospital, Boston, MA 02115 Harvard Digestive Diseases Center, Boston Children's Hospital, Boston, MA 02115 Harvard Medical School, Boston, MA 02115
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11
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Two types of syringomycin E channels in sphingomyelin-containing bilayers. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 45:91-8. [DOI: 10.1007/s00249-015-1101-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2015] [Revised: 10/19/2015] [Accepted: 11/11/2015] [Indexed: 10/22/2022]
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12
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Efimova SS, Malev VV, Ostroumova OS. Effects of Dipole Potential Modifiers on Heterogenic Lipid Bilayers. J Membr Biol 2015; 249:97-106. [PMID: 26454655 DOI: 10.1007/s00232-015-9852-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 09/29/2015] [Indexed: 01/29/2023]
Abstract
In this work, we examine the ability of dipole modifiers, flavonoids, and RH dyes to affect the dipole potential (φ d) and phase separation in membranes composed of ternary mixtures of POPC with different sphingolipids and sterols. Changes in the steady-state conductance induced by cation-ionophore complexes have been measured to evaluate the changes in dipole potential of planar lipid bilayers. Confocal fluorescence microscopy has been employed to investigate lipid segregation in giant unilamellar vesicles. The effects of flavonoids on φ d depend on lipid composition and dipole modifier type. The effectiveness of RH dyes to increase φ d depends on sphingolipid type but is not influenced by sterol content. Tested modifiers lead to partial or complete disruption of gel domains in bilayers composed of POPC, sphingomyelin, and cholesterol. Substitution of cholesterol to ergosterol or 7-dehydrocholesterol leads to a loss of fluidizing effects of modifiers except phloretin. This may be due to various compositions of gel domains. The lack of influence of modifiers on phase scenario in vesicles composed of ternary mixtures of POPC, cholesterol, and phytosphingosine or sphinganine is related to an absence of gel-like phase. It was concluded that the membrane lateral heterogeneity affects the dipole-modifying abilities of the agents that influence the magnitude of φ d by intercalation into the bilayer and orientation of its own large dipole moments (phloretin and RH dyes). The efficacy of modifiers that do not penetrate deeply and affect φ d through water adsorption (phlorizin, quercetin, and myricetin) is not influenced by lateral heterogeneity of membrane.
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Affiliation(s)
- Svetlana S Efimova
- Institute of Cytology of the Russian Academy of Sciences, Tikhoretsky ave. 4, St. Petersburg, Russia, 194064.
| | - Valery V Malev
- Institute of Cytology of the Russian Academy of Sciences, Tikhoretsky ave. 4, St. Petersburg, Russia, 194064.,St. Petersburg State University, Petergof, Russia, 198504
| | - Olga S Ostroumova
- Institute of Cytology of the Russian Academy of Sciences, Tikhoretsky ave. 4, St. Petersburg, Russia, 194064
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13
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Orchestration of membrane receptor signaling by membrane lipids. Biochimie 2015; 113:111-24. [DOI: 10.1016/j.biochi.2015.04.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 04/05/2015] [Indexed: 12/20/2022]
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14
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Madyarov SR. Effect of detergents, trypsin, and bivalent metal ions on interfacial activation and functioning of phospholipase D. BIOCHEMISTRY (MOSCOW) 2014; 79:687-93. [DOI: 10.1134/s0006297914070104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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15
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Rocha S, De Keersmaecker H, Hutchison JA, Vanhoorelbeke K, Martens JA, Hofkens J, Uji-i H. Membrane remodeling processes induced by phospholipase action. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:4743-4751. [PMID: 24694028 DOI: 10.1021/la500121f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Important cellular events such as division require drastic changes in the shape of the membrane. These remodeling processes can be triggered by the binding of specific proteins or by changes in membrane composition and are linked to phospholipid metabolism for which dedicated enzymes, named phospholipases, are responsible. Here wide-field fluorescence microscopy is used to visualize shape changes induced by the action of phospholipase A1 on dye-labeled supported membranes of POPC (1-palmitoyl-2-oleoly-sn-glycero-3-phosphocholine). Time-lapse imaging demonstrates that layers either shrink and disappear or fold and collapse into vesicles. These vesicles can undergo further transformations such as budding, tubulation, and pearling within 5 min of formation. Using dye-labeled phospholipases, we can monitor the presence of the enzyme at specific positions on the membrane as the shape transformations occur. Furthermore, incorporating the products of hydrolysis into POPC membranes is shown to induce transformations similar to those observed for enzyme action. The results suggest that phospholipase-mediated hydrolysis plays an important role in membrane transformations by altering the membrane composition, and a model is proposed for membrane curvature based on the presence and shape of hydrolysis products.
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Affiliation(s)
- Susana Rocha
- Molecular Imaging and Photonics, Faculty of Science and ‡Centre for Surface Chemistry and Catalysis, Faculty of Bioscience Engineering, KU Leuven , Belgium
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Castro BM, Prieto M, Silva LC. Ceramide: a simple sphingolipid with unique biophysical properties. Prog Lipid Res 2014; 54:53-67. [PMID: 24513486 DOI: 10.1016/j.plipres.2014.01.004] [Citation(s) in RCA: 266] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 01/29/2014] [Accepted: 01/29/2014] [Indexed: 02/06/2023]
Abstract
Ceramides are involved in a variety of cellular processes and in disease. Their biological functions are thought to depend on ceramides' unique biophysical properties, which promote strong alterations of cell membrane properties and consequent triggering of signaling events. Over the last decades, efforts were made to understand the impact of ceramide on membrane biophysical features. Several studies, performed in a multitude of membrane models, address ceramides' specific interactions, the effect of their acyl chain structure and the influence of membrane lipid composition and properties on ceramide biophysical outcome. In this review, a rationale for the multiple and complex changes promoted by ceramide is provided, highlighting, on a comprehensive and critical manner, the interactions between ceramides and specific lipids and/or lipid phases. Focus is also given to the interplay between ceramide and cholesterol, particularly in lipid raft-mimicking mixtures, an issue of intense debate due to the urgent need to understand the biophysical impact of ceramide formation in models resembling the cell membrane. The implications of ceramide-induced biophysical changes on lipid-protein interactions and cell signaling are also discussed, together with the emerging evidence for the existence of ceramide-gel like domains in cellular membranes.
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Affiliation(s)
- Bruno M Castro
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Complexo I, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Manuel Prieto
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Complexo I, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Liana C Silva
- iMed.UL - Research Institute for Medicines and Pharmaceutical Sciences, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal.
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17
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Ibarguren M, Sot J, Montes LR, Vasil AI, Vasil ML, Goñi FM, Alonso A. Recruitment of a phospholipase C/sphingomyelinase into non-lamellar lipid droplets during hydrolysis of lipid bilayers. Chem Phys Lipids 2012; 166:12-7. [PMID: 23253877 DOI: 10.1016/j.chemphyslip.2012.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 11/30/2012] [Accepted: 12/01/2012] [Indexed: 01/05/2023]
Abstract
When giant unilamellar vesicles (GUVs) composed of sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, and cholesterol are treated with PlcHR(2), a phospholipase C/sphingomyelinase from Pseudomonas aeruginosa, the initial stages of lipid hydrolysis do not cause large changes in vesicle morphology (Ibarguren et al., 2011). However, when hydrolysis progresses confocal fluorescence microscopy reveals the formation of lipid aggregates, whose morphology is not compatible with that of bilayers. Smaller vesicles or droplets can also be seen inside the GUV. Our studies indicate that these aggregates or droplets are enriched in the non-lamellar lipid ceramide, an end-product of PlcHR(2) reaction. Moreover, the aggregates/droplets appear enriched in the hydrolytic enzyme PlcHR(2). At a final stage GUVs containing the enzyme-enriched droplets disintegrate and vanish from the microscope field. The observed non-lamellar enzyme-rich structures may be related to intermediates in the process of aggregation and fusion although the experimental design prevents vesicle free diffusion in the aqueous medium, thus actual aggregation or fusion cannot be observed.
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Affiliation(s)
- Maitane Ibarguren
- Unidad de Biofísica (Centro Mixto CSIS-UPV/EHU), Departamento de Bioquímica, Universidad del País Vasco, Barrio Sarriena s/n, 48940 Bilbao, Spain
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Increased exposure of phosphatidylethanolamine on the surface of tumor vascular endothelium. Neoplasia 2011; 13:299-308. [PMID: 21472134 DOI: 10.1593/neo.101366] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 01/12/2011] [Accepted: 01/17/2011] [Indexed: 01/01/2023] Open
Abstract
We have previously shown that oxidative stress within the tumor microenvironment causes phosphatidylserine (PS) to redistribute from the inner to the outer membrane leaflet of the endothelial cells (EC) creating a highly specific marker for the tumor vasculature. Because the distribution of phosphatidylethanolamine (PE) and PS within the membrane is coregulated, we reasoned that PE would also be localized in the outer membrane leaflet of tumor EC. To demonstrate this, the PE-binding peptide duramycin was biotinylated and used to determine the distribution of PE on EC in vitro and in vivo. Exposure of cultured EC to hypoxia, acidity, reactive oxygen species, or irradiation resulted in the formation of membrane blebs that were intensely PE-positive. When biotinylated duramycin was intravenously injected into tumor-bearing mice, it preferentially localized to the luminal surface of the vascular endothelium. Depending on tumor type, 13% to 56% of the tumor vessels stained positive for PE. PE-positive vessels were observed in and around hypoxic regions of the tumor. With the exception of intertubular vessels of the kidney, normal vessels remained unstained. To test the potential of PE as a biomarker for imaging, duramycin was conjugated to the near-infrared fluorophore 800CW and used for optical imaging of RM-9 prostate carcinomas. The near-infrared probe was easily detected within tumors in live animals. These results show that PE, like PS, becomes exposed on tumor vascular endothelium of multiple types of tumors and holds promise as a biomarker for noninvasive imaging and drug targeting.
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Monitoring of membrane collapse and enzymatic reaction with single giant liposomes embedded in agarose gel. Colloid Polym Sci 2011. [DOI: 10.1007/s00396-011-2463-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ibarguren M, López DJ, Montes LR, Sot J, Vasil AI, Vasil ML, Goñi FM, Alonso A. Imaging the early stages of phospholipase C/sphingomyelinase activity on vesicles containing coexisting ordered-disordered and gel-fluid domains. J Lipid Res 2011; 52:635-45. [PMID: 21252263 DOI: 10.1194/jlr.m012591] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The binding and early stages of activity of a phospholipase C/sphingomyelinase from Pseudomonas aeruginosa on giant unilamellar vesicles (GUV) have been monitored using fluorescence confocal microscopy. Both the lipids and the enzyme were labeled with specific fluorescent markers. GUV consisted of a mixture of phosphatidylcholine, sphingomyelin, phosphatidylethanolamine, and cholesterol in equimolar ratios, to which 5-10 mol% of the enzyme end-product ceramide and/or diacylglycerol were occasionally added. Morphological examination of the GUV in the presence of enzyme reveals that, although the enzyme diffuses rapidly throughout the observation chamber, detectable enzyme binding appears to be a slow, random process, with new bound-enzyme-containing vesicles appearing for several minutes. Enzyme binding to the vesicles appears to be a cooperative process. After the initial cluster of bound enzyme is detected, further binding and catalytic activity follow rapidly. After the activity has started, the enzyme is not released by repeated washing, suggesting a "scooting" mechanism for the hydrolytic activity. The enzyme preferentially binds the more disordered domains, and, in most cases, the catalytic activity causes the disordering of the other domains. Simultaneously, peanut- or figure-eight-shaped vesicles containing two separate lipid domains become spherical. At a further stage of lipid hydrolysis, lipid aggregates are formed and vesicles disintegrate.
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Affiliation(s)
- Maitane Ibarguren
- Unidad de Biofísica (Centro Mixto CSIC-UPV/EHU), Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
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Busto JV, Sot J, Requejo-Isidro J, Goñi FM, Alonso A. Cholesterol displaces palmitoylceramide from its tight packing with palmitoylsphingomyelin in the absence of a liquid-disordered phase. Biophys J 2010; 99:1119-28. [PMID: 20712995 DOI: 10.1016/j.bpj.2010.05.032] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 04/22/2010] [Accepted: 05/17/2010] [Indexed: 02/06/2023] Open
Abstract
A set of different biophysical approaches has been used to explore the phase behavior of palmitoylsphingomyelin (pSM)/cholesterol (Chol) model membranes in the presence and absence of palmitoylceramide (pCer). Fluorescence spectroscopy of di-4-ANEPPDHQ-stained pSM/Chol vesicles and atomic force microscopy of supported planar bilayers show gel L(beta)/liquid-ordered (L(o)) phase coexistence within the range X(Chol) = 0-0.25 at 22 degrees C. At the latter compositional point and beyond, a single L(o) pSM/Chol phase is detected. In ternary pSM/Chol/pCer mixtures, differential scanning calorimetry of multilamellar vesicles and confocal fluorescence microscopy of giant unilamellar vesicles concur in showing immiscibility, but no displacement, between L(o) cholesterol-enriched (pSM/Chol) and gel-like ceramide-enriched (pSM/pCer) phases at high pSM/(Chol + pCer) ratios. At higher cholesterol content, pCer is unable to displace cholesterol at any extent, even at X(Chol) < 0.25. It is interesting that an opposite strong cholesterol-mediated pCer displacement from its tight packing with pSM is clearly detected, completely abolishing the pCer ability to generate large microdomains and giving rise instead to a single ternary phase. These observations in model membranes in the absence of the lipids commonly used to form a liquid-disordered phase support the role of cholesterol as the key determinant in controlling its own displacement from L(o) domains by ceramide upon sphingomyelinase activity.
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Affiliation(s)
- Jon V Busto
- Unidad de Biofísica (Centro Mixto CSIC-UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
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Fanani ML, Hartel S, Maggio B, De Tullio L, Jara J, Olmos F, Oliveira RG. The action of sphingomyelinase in lipid monolayers as revealed by microscopic image analysis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1309-23. [DOI: 10.1016/j.bbamem.2010.01.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Revised: 12/16/2009] [Accepted: 01/04/2010] [Indexed: 11/26/2022]
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24
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Vieira CR, Munoz-Olaya JM, Sot J, Jiménez-Baranda S, Izquierdo-Useros N, Abad JL, Apellániz B, Delgado R, Martinez-Picado J, Alonso A, Casas J, Nieva JL, Fabriás G, Mañes S, Goñi FM. Dihydrosphingomyelin Impairs HIV-1 Infection by Rigidifying Liquid-Ordered Membrane Domains. ACTA ACUST UNITED AC 2010; 17:766-75. [DOI: 10.1016/j.chembiol.2010.05.023] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Revised: 05/13/2010] [Accepted: 05/14/2010] [Indexed: 12/20/2022]
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25
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López-Montero I, Monroy F, Vélez M, Devaux PF. Ceramide: From lateral segregation to mechanical stress. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1348-56. [DOI: 10.1016/j.bbamem.2009.12.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 11/25/2009] [Accepted: 12/09/2009] [Indexed: 12/13/2022]
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26
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Ramirez DMC, Ogilvie WW, Johnston LJ. NBD-cholesterol probes to track cholesterol distribution in model membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:558-68. [DOI: 10.1016/j.bbamem.2009.12.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Revised: 11/17/2009] [Accepted: 12/08/2009] [Indexed: 01/08/2023]
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27
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Sandhoff R. Very long chain sphingolipids: Tissue expression, function and synthesis. FEBS Lett 2009; 584:1907-13. [DOI: 10.1016/j.febslet.2009.12.032] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Accepted: 12/18/2009] [Indexed: 11/26/2022]
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28
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Ira, Zou S, Ramirez DMC, Vanderlip S, Ogilvie W, Jakubek ZJ, Johnston LJ. Enzymatic generation of ceramide induces membrane restructuring: Correlated AFM and fluorescence imaging of supported bilayers. J Struct Biol 2009; 168:78-89. [PMID: 19348948 DOI: 10.1016/j.jsb.2009.03.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Revised: 03/23/2009] [Accepted: 03/27/2009] [Indexed: 01/15/2023]
Abstract
The effect of enzymatic generation of ceramide on phase separated bilayers with a mixture of co-existing fluid and liquid-ordered phases has been examined using a combination of atomic force microscopy (AFM) and fluorescence imaging. Supported lipid bilayers prepared from a DOPC/sphingomyelin/cholesterol mixture were imaged prior to, during and after incubation with sphingomyelinase by total internal reflection fluorescence (TIRF) microscopy. Enzyme treatment resulted in the growth of large dye-excluded regions. The growth kinetics for these patches are consistent with activity of a variable number of enzyme molecules in different regions of the bilayer. Correlated AFM and fluorescence imaging shows that some of the large dye-excluded patches form around the original liquid-ordered domains, which become heterogeneous in height with many raised ceramide-rich regions around their periphery. However, some of the dye-excluded patches correspond to areas of the bilayer where the initial domains have largely or partially disappeared. The dye-excluded patches observed by fluorescence are shown to be areas of increased adhesion in lateral deflection AFM images and are postulated to form by incorporation of both cholesterol and ceramide in the original fluid phase and to vary in composition throughout the bilayer. This is evident from the observation that the dye-excluded areas are all detected as areas of increased friction, but do not always show a distinct height difference in topographic images. These results highlight the utility of a multi-modal imaging approach for understanding the complex membrane restructuring that occurs upon enzymatic generation of ceramide.
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Affiliation(s)
- Ira
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ont., Canada
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29
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Staneva G, Momchilova A, Wolf C, Quinn PJ, Koumanov K. Membrane microdomains: Role of ceramides in the maintenance of their structure and functions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:666-75. [DOI: 10.1016/j.bbamem.2008.10.026] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Revised: 10/13/2008] [Accepted: 10/29/2008] [Indexed: 12/12/2022]
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30
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Popov J, Vobornik D, Coban O, Keating E, Miller D, Francis J, Petersen NO, Johnston LJ. Chemical mapping of ceramide distribution in sphingomyelin-rich domains in monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:13502-13508. [PMID: 18973350 DOI: 10.1021/la8007552] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The incorporation of ceramide in phase-separated monolayers of ternary lipid mixtures has been studied by a combination of atomic force microscopy (AFM), fluorescence, and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Replacement of a fraction of the sphingomyelin by ceramide in DOPC/SM/cholesterol monolayers leads to changes in the SM-cholesterol-rich liquid-ordered domains. AFM shows the formation of heterogeneous domains with small raised islands that are assigned to a ceramide-rich gel phase. ToF-SIMS provides conclusive evidence for the localization of SM and ceramide in ordered domains and shows that ceramide is heterogeneously distributed in small islands throughout the domains. The results indicate the utility of combining AFM and ToF-SIMS for understanding compositions of phase-separated membranes.
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Affiliation(s)
- Jesse Popov
- Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada
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31
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Goñi FM, Alonso A. Effects of ceramide and other simple sphingolipids on membrane lateral structure. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1788:169-77. [PMID: 18848519 DOI: 10.1016/j.bbamem.2008.09.002] [Citation(s) in RCA: 167] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Revised: 09/09/2008] [Accepted: 09/10/2008] [Indexed: 10/21/2022]
Abstract
The available data concerning the ability of ceramide and other simple sphingolipids to segregate laterally into rigid, gel-like domains in a fluid bilayer has been reviewed. Ceramides give rise to rigid ceramide-enriched domains when their N-acyl chain is longer than C12. The high melting temperature of hydrated ceramides, revealing a tight intermolecular interaction, is probably responsible for their lateral segregation. Ceramides compete with cholesterol for the formation of domains with lipids such as sphingomyelin or saturated phosphatidylcholines; under these conditions displacement of cholesterol by ceramide involves a transition from a liquid-ordered to a gel-like phase in the domains involved. When ceramide is generated in situ by a sphingomyelinase, instead of being premixed with the other lipids, gel-like domain formation occurs as well, although the topology of the domains may not be the same, the enzyme causing clustering of domains that is not detected with premixed ceramide. Ceramide-1-phosphate is not likely to form domains in fluid bilayers, and the same is true of sphingosine and of sphingosine-1-phosphate. However, sphingosine does rigidify pre-existing gel domains in mixed bilayers.
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Affiliation(s)
- Félix M Goñi
- Unidad de Biofísica (Centro Mixto CSIC-UPV/EHU), Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain.
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32
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Sot J, Ibarguren M, Busto JV, Montes LR, Goñi FM, Alonso A. Cholesterol displacement by ceramide in sphingomyelin-containing liquid-ordered domains, and generation of gel regions in giant lipidic vesicles. FEBS Lett 2008; 582:3230-6. [PMID: 18755187 DOI: 10.1016/j.febslet.2008.08.016] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 08/12/2008] [Accepted: 08/15/2008] [Indexed: 12/20/2022]
Abstract
Fluorescence confocal microscopy and differential scanning calorimetry are used in combination to study the phase behaviour of bilayers composed of PC:PE:SM:Chol equimolecular mixtures, in the presence or absence of 10 mol% egg ceramide. In the absence of ceramide, separate liquid-ordered and liquid-disordered domains are observed in giant unilamellar vesicles. In the presence of ceramide, gel-like domains appear within the liquid-ordered regions. The melting properties of these gel-like domains resemble those of SM:ceramide binary mixtures, suggesting Chol displacement by ceramide from SM:Chol-rich liquid-ordered regions. Thus three kinds of domains coexist within a single vesicle in the presence of ceramide: gel, liquid-ordered, and liquid-disordered. In contrast, when 10 mol% egg diacylglycerol is added instead of ceramide, homogeneous vesicles, consisting only of liquid-disordered bilayers, are observed.
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Affiliation(s)
- Jesús Sot
- Unidad de Biofísica (Centro Mixto CSIC-UPV/EHU), Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain
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33
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Staneva G, Chachaty C, Wolf C, Koumanov K, Quinn PJ. The role of sphingomyelin in regulating phase coexistence in complex lipid model membranes: competition between ceramide and cholesterol. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:2727-39. [PMID: 18722999 DOI: 10.1016/j.bbamem.2008.07.025] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Revised: 07/14/2008] [Accepted: 07/28/2008] [Indexed: 11/27/2022]
Abstract
The structure, thermotropic phase behavior, dynamic motion and order parameters of bilayer dispersions of egg phosphatidylcholine, egg sphingomyelin, egg ceramide and cholesterol have been determined. The coexistence of gel, liquid-ordered and liquid-disordered structure has been determined by peak fitting analysis of synchrotron X-ray powder patterns. Order parameters and extent of distribution of 16-doxyl-stearic acid spin probe between ordered and disordered environments has been estimated by ESR spectral simulation methods. The presence of ceramide in proportions up to 20 mol% in phosphatidylcholine is characterized by gel-fluid phase coexistence at temperatures up to 46 degrees C depending on the amount of ceramide. Cholesterol tends to destabilize the ceramide-rich domains formed in phosphatidylcholine while sphingomyelin, by formation of stable complexes with ceramide, tends to stabilize these domains. The stability of sphingomyelin-ceramide complexes is evident from the persistence of highly ordered structure probed by ESR spectroscopy and appearance of a sharp wide-angle X-ray reflection at temperatures higher than the gel-fluid transition of ceramide alone in egg phosphatidylcholine bilayers. The competition between ceramide and cholesterol for interaction with sphingomyelin is discussed in terms of control of lipid-mediated signaling pathways by sphingomyelinase and phospholipase A2.
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Affiliation(s)
- Galya Staneva
- Institute of Biophysics, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl.21, 1113 Sofia, Bulgaria.
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Marconescu A, Thorpe PE. Coincident exposure of phosphatidylethanolamine and anionic phospholipids on the surface of irradiated cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:2217-24. [PMID: 18570887 DOI: 10.1016/j.bbamem.2008.05.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Revised: 05/09/2008] [Accepted: 05/12/2008] [Indexed: 01/03/2023]
Abstract
The major anionic phospholipid, phosphatidylserine (PS), and the neutral phospholipid, phosphatidylethanolamine (PE), are largely confined to the inner leaflet of the plasma membrane bilayer in mammalian cells under normal conditions. This asymmetry is lost when cells undergo apoptosis, become activated, or are exposed to irradiation, reactive oxygen species or certain drugs. It is not known whether exposure of anionic phospholipids (APLs) and PE occurs simultaneously or in the same region of the plasma membrane. Here we examined the coincidence of exposure of APLs and PE on the surface of bovine aortic endothelial cells and NS0 myeloma cells after irradiation. The cells were irradiated (5 Gy) and stained for APLs and PE using liposomes coated with either an Fab' fragment of a PS-binding antibody (bavituximab) or a PE-binding peptide (duramycin). Using live cell imaging and flow cytometry, we showed that irradiation leads to synchronous externalization of APLs and PE. The time course of appearance of APLs and PE on the cell surface was the same and the two phospholipid types remained colocalized over time. Distinct patches double positive for APLs and PE were visible. Larger areas of APLs and PE appeared to have detached from the cytoskeleton to form membrane blebs which protruded and drifted on the cell surface. We conclude that APLs and PE coincidently appear on the external leaflet of the plasma membrane of cells after irradiation. Probably, this is because PE and the major APL, PS, share common regulatory mechanisms of translocation.
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Affiliation(s)
- Andrei Marconescu
- Department of Pharmacology and Simmons and Hamon Cancer Centers, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
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35
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Maggio B, Borioli GA, Del Boca M, De Tullio L, Fanani ML, Oliveira RG, Rosetti CM, Wilke N. Composition-driven surface domain structuring mediated by sphingolipids and membrane-active proteins. Above the nano- but under the micro-scale: mesoscopic biochemical/structural cross-talk in biomembranes. Cell Biochem Biophys 2007; 50:79-109. [PMID: 17968678 DOI: 10.1007/s12013-007-9004-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2007] [Indexed: 10/22/2022]
Abstract
Biomembranes contain a wide variety of lipids and proteins within an essentially two-dimensional structure. The coexistence of such a large number of molecular species causes local tensions that frequently relax into a phase or compositional immiscibility along the lateral and transverse planes of the interface. As a consequence, a substantial microheterogeneity of the surface topography develops and that depends not only on the lipid-protein composition, but also on the lateral and transverse tensions generated as a consequence of molecular interactions. The presence of proteins, and immiscibility among lipids, constitute major perturbing factors for the membrane sculpturing both in terms of its surface topography and dynamics. In this work, we will summarize some recent evidences for the involvement of membrane-associated, both extrinsic and amphitropic, proteins as well as membrane-active phosphohydrolytic enzymes and sphingolipids in driving lateral segregation of phase domains thus determining long-range surface topography.
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Affiliation(s)
- Bruno Maggio
- Departamento de Química Biológica, Facultad de Ciencias Químicas, Centro de Investigaciones en Química Biológica de Córdoba, Universidad Nacional de Córdoba - CONICET, Argentina.
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36
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Ira, Johnston LJ. Sphingomyelinase generation of ceramide promotes clustering of nanoscale domains in supported bilayer membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:185-97. [PMID: 17988649 DOI: 10.1016/j.bbamem.2007.09.021] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Revised: 09/20/2007] [Accepted: 09/21/2007] [Indexed: 11/29/2022]
Abstract
The effects of ceramide incorporation in supported bilayers prepared from ternary lipid mixtures which have small nanoscale domains have been examined using atomic force and fluorescence microscopy. Both direct ceramide incorporation in vesicles used to prepare the supported bilayers and enzymatic hydrolysis of SM by sphingomyelinase were compared for membranes prepared from 5:5:1 DOPC/sphingomyelin/cholesterol mixtures. Both methods of ceramide incorporation resulted in enlargement of the initial small ordered domains. However, enzymatic ceramide generation led to a much more pronounced restructuring of the bilayer to give large clusters of domains with adjacent areas of a lower phase. The individual domains were heterogeneous with two distinct heights, the highest of which is assigned to a ceramide-rich phase which is hypothesized to occur via ceramide flip-flop to the lower leaflet with formation of a raised domain due to negative membrane curvature. A combination of AFM and fluorescence showed that the bilayer restructuring starts rapidly after enzyme addition, with formation of large clusters of domains at sites of high enzyme activity. The clustering of domains is accompanied by redistribution of fluid phase to the periphery of the domain clusters and there is a continued slow evolution of the bilayer over a period of an hour or more after the enzyme is removed. The relevance of the observed clustering of small nanoscale domains to the postulated coalescence of raft domains to form large signaling platforms is discussed.
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Affiliation(s)
- Ira
- Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6
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37
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Veatch SL. From small fluctuations to large-scale phase separation: Lateral organization in model membranes containing cholesterol. Semin Cell Dev Biol 2007; 18:573-82. [DOI: 10.1016/j.semcdb.2007.08.016] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Revised: 08/23/2007] [Accepted: 08/29/2007] [Indexed: 01/09/2023]
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38
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Fa N, Lins L, Courtoy PJ, Dufrêne Y, Van Der Smissen P, Brasseur R, Tyteca D, Mingeot-Leclercq MP. Decrease of elastic moduli of DOPC bilayers induced by a macrolide antibiotic, azithromycin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1830-8. [PMID: 17537401 DOI: 10.1016/j.bbamem.2007.04.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2007] [Revised: 04/06/2007] [Accepted: 04/10/2007] [Indexed: 10/23/2022]
Abstract
The elastic properties of membrane bilayers are key parameters that control its deformation and can be affected by pharmacological agents. Our previous atomic force microscopy studies revealed that the macrolide antibiotic, azithromycin, leads to erosion of DPPC domains in a fluid DOPC matrix [A. Berquand, M. P. Mingeot-Leclercq, Y. F. Dufrene, Real-time imaging of drug-membrane interactions by atomic force microscopy, Biochim. Biophys. Acta 1664 (2004) 198-205.]. Since this observation could be due to an effect on DOPC cohesion, we investigated the effect of azithromycin on elastic properties of DOPC giant unilamellar vesicles (GUVs). Microcinematographic and morphometric analyses revealed that azithromycin addition enhanced lipid membranes fluctuations, leading to eventual disruption of the largest GUVs. These effects were related to change of elastic moduli of DOPC, quantified by the micropipette aspiration technique. Azithromycin decreased both the bending modulus (k(c), from 23.1+/-3.5 to 10.6+/-4.5 k(B)T) and the apparent area compressibility modulus (K(app), from 176+/-35 to 113+/-25 mN/m). These data suggested that insertion of azithromycin into the DOPC bilayer reduced the requirement level of both the energy for thermal fluctuations and the stress to stretch the bilayer. Computer modeling of azithromycin interaction with DOPC bilayer, based on minimal energy, independently predicted that azithromycin (i) inserts at the interface of phospholipid bilayers, (ii) decreases the energy of interaction between DOPC molecules, and (iii) increases the mean surface occupied by each phospholipid molecule. We conclude that azithromycin inserts into the DOPC lipid bilayer, so as to decrease its cohesion and to facilitate the merging of DPPC into the DOPC fluid matrix, as observed by atomic force microscopy. These investigations, based on three complementary approaches, provide the first biophysical evidence for the ability of an amphiphilic antibiotic to alter lipid elastic moduli. This may be an important determinant for drug: lipid interactions and cellular pharmacology.
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Affiliation(s)
- N Fa
- Université Catholique de Louvain, Unité de Pharmacologie Cellulaire et Moléculaire, Avenue E. Mounier 73, Bt 7370, B-1200 Brussels, Belgium
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39
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López-Montero I, Vélez M, Devaux PF. Surface tension induced by sphingomyelin to ceramide conversion in lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:553-61. [PMID: 17292325 DOI: 10.1016/j.bbamem.2007.01.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Revised: 12/13/2006] [Accepted: 01/02/2007] [Indexed: 11/18/2022]
Abstract
We have investigated the effect of sphingomyelin (SM) to ceramide enzymatic conversion on lipid bilayers using Giant Unilamellar Vesicles (GUVs). Sphingomyelinase was added externally to GUVs containing various proportions of SM. In situ asymmetrical SM conversion to ceramide reduced the area of one leaflet. In the absence of equilibration of all the lipids between the two leaflets, a mismatch between the two monolayers was generated. The tension generated by this mismatch was sufficient to trigger the formation of membrane defects and total vesicle collapse at relatively low percentage of SM ( approximately 5% mol). The formation of nanometric size defects was visualised by AFM in supported bilayers. Vesicle rupture was prevented in two circumstances: (a) in GUVs containing a mixture of l(d) and l(o) domains and (b) in GUVs containing 5% lyso-phosphatidylcholine. In both cases, the accumulation of enough ceramide (at initial SM concentration of 10%) allowed the formation of ceramide-rich domains. The coupling between the two asymmetrical monolayers and the condensing effect produced by the newly formed ceramide generated a tension that could underlie the mechanism through which ceramide formation induces membrane modifications observed during the late stages of apoptosis.
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Affiliation(s)
- Iván López-Montero
- Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie 75005 Paris, France
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