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Gupta A, Muralidharan S, Torta F, Wenk MR, Wohland T. Long acyl chain ceramides govern cholesterol and cytoskeleton dependence of membrane outer leaflet dynamics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183153. [PMID: 31857071 DOI: 10.1016/j.bbamem.2019.183153] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 12/09/2019] [Indexed: 12/20/2022]
Abstract
The spatiotemporal dynamics of the plasma membrane is a consequence of fine-tuned interactions between membrane components. However, the precise identity of molecular factors that maintain this delicate balance, which is lost even in cell membrane derived mimics, remains elusive. Here, we use two cell lines, CHO-K1 and RBL-2H3, which show differences in outer membrane organization, dynamics, and cytoskeleton coupling, to investigate the underlying factors. To our surprise, knock-down of the cytoskeleton-interacting Immunoglobulin E receptor, which is abundant in RBL-2H3 but not in CHO-K1 cells, is not responsible for lipid confinement or cytoskeleton coupling. A subsequent lipidomic analysis of the two cell membranes revealed differences in total membrane ceramide content (C16 to C24). Analysis of the dynamics and organization of ceramide treated live cell membranes by imaging fluorescence correlation spectroscopy demonstrates that C24 and C16 saturated ceramides uniquely alter membrane dynamics by promoting the formation of cholesterol-independent domains and by elevating the inter-leaflet coupling.
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Affiliation(s)
- Anjali Gupta
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore; NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, 117557, Singapore
| | - Sneha Muralidharan
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore
| | - Federico Torta
- Department of Biochemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore
| | - Markus R Wenk
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore; Department of Biochemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore
| | - Thorsten Wohland
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore; NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, 117557, Singapore; Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.
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2
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Holowka D, Thanapuasuwan K, Baird B. Short chain ceramides disrupt immunoreceptor signaling by inhibiting segregation of Lo from Ld Plasma membrane components. Biol Open 2018; 7:bio.034702. [PMID: 30097519 PMCID: PMC6176950 DOI: 10.1242/bio.034702] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Lipid phase heterogeneity in plasma membranes is thought to play a key role in targeting cellular signaling, but efforts to test lipid raft and related hypotheses are limited by the spatially dynamic nature of these phase-based structures in cells and by experimental characterization tools. We suggest that perturbation of plasma membrane structure by lipid derivatives offers a general method for assessing functional roles for ordered lipid regions in membrane and cell biology. We previously reported that short chain ceramides with either C2 or C6 acyl chains inhibit antigen-stimulated Ca2+ mobilization (Gidwani et al., 2003). We now show that these short chain ceramides inhibit liquid order (Lo)-liquid disorder (Ld) phase separation in giant plasma membrane vesicles that normally occurs at low temperatures. Furthermore, they are effective inhibitors of tyrosine phosphorylation stimulated by antigen, as well as store-operated Ca2+ entry. In Jurkat T cells, C6-ceramide is also effective at inhibiting Ca2+ mobilization stimulated by either anti-TCR or thapsigargin, consistent with the view that these short chain ceramides effectively interfere with functional responses that depend on ordered lipid regions in the plasma membrane. Summary: Our manuscript describes how perturbation of plasma membrane structure by short chain ceramides offers a general method for assessing functional roles for ordered lipid regions in membrane and cell biology.
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Affiliation(s)
- David Holowka
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Kankanit Thanapuasuwan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Barbara Baird
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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3
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Li L, Dwivedi M, Erwin N, Möbitz S, Nussbaumer P, Winter R. Interaction of KRas4B protein with C6-ceramide containing lipid model membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1008-1014. [PMID: 29357287 DOI: 10.1016/j.bbamem.2018.01.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 01/14/2018] [Accepted: 01/15/2018] [Indexed: 01/02/2023]
Abstract
Ras proteins are oncoproteins which play a pivotal role in cellular signaling pathways. All Ras proteins' signaling strongly depends on their correct localization in the cell membrane. Over 30% of cancers are driven by mutant Ras proteins, and KRas4B is the Ras isoform most frequently mutated. C6-ceramide has been shown to inhibit the growth activity of KRas4B mutated cells. However, the mechanism underlying this inhibition remains elusive. Here, we established a heterogeneous model biomembrane containing C6-ceramide. C6-ceramide incorporation does not disrupt the lipid membrane. Addition of KRas4B leads to drastic changes in the lateral membrane organization of the membrane, however. In contrast to the partitioning behavior in other membranes, KRas4B forms small, monodisperse nanoclusters dispersed in a fluid-like environment, in all likelihood induced by some kind of lipid sorting mechanism. Fluorescence cross-correlation data indicate no direct interaction between C6-ceramide and KRas4B, suggesting that KRas4B essentially recruits other lipids. A FRET-based binding assay reveals that the stability of KRas4B proteins inserted into the membrane containing C6-ceramide is reduced. Based on the combined results obtained, we postulate a molecular mechanism for the inhibition of KRas4B mutated cells' activity through C6-ceramide.
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Affiliation(s)
- Lei Li
- Faculty of Chemistry and Chemical Biology, Physical Chemistry I, Technical University of Dortmund, Otto-Hahn-Strasse 4a, 44221 Dortmund, Germany; International Max Planck Research School (IMPRS) in Chemical and Molecular Biology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Mridula Dwivedi
- Faculty of Chemistry and Chemical Biology, Physical Chemistry I, Technical University of Dortmund, Otto-Hahn-Strasse 4a, 44221 Dortmund, Germany
| | - Nelli Erwin
- Faculty of Chemistry and Chemical Biology, Physical Chemistry I, Technical University of Dortmund, Otto-Hahn-Strasse 4a, 44221 Dortmund, Germany; International Max Planck Research School (IMPRS) in Chemical and Molecular Biology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Simone Möbitz
- Faculty of Chemistry and Chemical Biology, Physical Chemistry I, Technical University of Dortmund, Otto-Hahn-Strasse 4a, 44221 Dortmund, Germany
| | - Peter Nussbaumer
- Lead Discovery Center GmbH, Otto-Hahn-Strasse 15, 44227 Dortmund, Germany
| | - Roland Winter
- Faculty of Chemistry and Chemical Biology, Physical Chemistry I, Technical University of Dortmund, Otto-Hahn-Strasse 4a, 44221 Dortmund, Germany.
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4
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Rodriguez-Cuenca S, Pellegrinelli V, Campbell M, Oresic M, Vidal-Puig A. Sphingolipids and glycerophospholipids - The "ying and yang" of lipotoxicity in metabolic diseases. Prog Lipid Res 2017; 66:14-29. [PMID: 28104532 DOI: 10.1016/j.plipres.2017.01.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 11/30/2016] [Accepted: 01/05/2017] [Indexed: 12/14/2022]
Abstract
Sphingolipids in general and ceramides in particular, contribute to pathophysiological mechanisms by modifying signalling and metabolic pathways. Here, we present the available evidence for a bidirectional homeostatic crosstalk between sphingolipids and glycerophospholipids, whose dysregulation contributes to lipotoxicity induced metabolic stress. The initial evidence for this crosstalk originates from simulated models designed to investigate the biophysical properties of sphingolipids in plasma membrane representations. In this review, we reinterpret some of the original findings and conceptualise them as a sort of "ying/yang" interaction model of opposed/complementary forces, which is consistent with the current knowledge of lipid homeostasis and pathophysiology. We also propose that the dysregulation of the balance between sphingolipids and glycerophospholipids results in a lipotoxic insult relevant in the pathophysiology of common metabolic diseases, typically characterised by their increased ceramide/sphingosine pools.
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Affiliation(s)
- S Rodriguez-Cuenca
- Metabolic Research Laboratories, Wellcome Trust MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge. Cambridge, UK.
| | - V Pellegrinelli
- Metabolic Research Laboratories, Wellcome Trust MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge. Cambridge, UK
| | - M Campbell
- Metabolic Research Laboratories, Wellcome Trust MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge. Cambridge, UK
| | - M Oresic
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, FI -20520 Turku, Finland
| | - A Vidal-Puig
- Metabolic Research Laboratories, Wellcome Trust MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge. Cambridge, UK; Wellcome Trust Sanger Institute, Hinxton, UK.
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5
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Villar VAM, Cuevas S, Zheng X, Jose PA. Localization and signaling of GPCRs in lipid rafts. Methods Cell Biol 2016; 132:3-23. [DOI: 10.1016/bs.mcb.2015.11.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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6
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Effects of Aging and Experimentally Induced Modifications of Signal Pathways on Insulin-Induced Shifts of Glucose Metabolism in the Rat Neocortex. NEUROPHYSIOLOGY+ 2015. [DOI: 10.1007/s11062-015-9491-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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7
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Babenko NA, Kharchenko VS. Modulation of Insulin Sensitivity of Hepatocytes by the Pharmacological Downregulation of Phospholipase D. Int J Endocrinol 2015; 2015:794838. [PMID: 26089893 PMCID: PMC4458285 DOI: 10.1155/2015/794838] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 04/30/2015] [Accepted: 05/11/2015] [Indexed: 12/13/2022] Open
Abstract
Background. The role of phospholipase D (PLD) as a positive modulator of glucose uptake activation by insulin in muscle and adipose cells has been demonstrated. The role of PLD in the regulation of glucose metabolism by insulin in the primary hepatocytes has been determined in this study. Methods. For this purpose, we studied effects of inhibitors of PLD on glucose uptake and glycogen synthesis stimulation by insulin. To determine the PLD activity, the method based on determination of products of transphosphatidylation reaction, phosphatidylethanol or phosphatidylbutanol, was used. Results. Inhibition of PLD by a general antagonist (1-butanol) or specific inhibitor, halopemide, or N-hexanoylsphingosine, or by cellular ceramides accumulated in doxorubicin-treated hepatocytes decreased insulin-stimulated glucose metabolism. Doxorubicin-induced hepatocytes resistance to insulin action could be abolished by inhibition of ceramide production. Halopemide could nullify this effect. Addition of propranolol, as well as inhibitors of phosphatidylinositol 3-kinase (PI3-kinase) (wortmannin, LY294002) or suppressors of Akt phosphorylation/activity, luteolin-7-O-glucoside or apigenin-7-O-glucoside, to the culture media could block cell response to insulin action. Conclusion. PLD plays an important role in the insulin signaling in the hepatocytes. PLD is activated downstream of PI3-kinase and Akt and is highly sensitive to ceramide content in the liver cells.
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Affiliation(s)
- Nataliya A. Babenko
- Department of Physiology of Ontogenesis, Biology Research Institute, Karazin Kharkov National University, Svobody Square 4, Kharkov 61022, Ukraine
- *Nataliya A. Babenko:
| | - Vitalina S. Kharchenko
- Department of Physiology of Ontogenesis, Biology Research Institute, Karazin Kharkov National University, Svobody Square 4, Kharkov 61022, Ukraine
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8
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Smith NL, Hammond S, Gadi D, Wagenknecht-Wiesner A, Baird B, Holowka D. Sphingosine derivatives inhibit cell signaling by electrostatically neutralizing polyphosphoinositides at the plasma membrane. SELF NONSELF 2014; 1:133-143. [PMID: 21423874 DOI: 10.4161/self.1.2.11672] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Mast cell stimulation via IgE receptors causes activation of multiple processes, including Ca(2+) mobilization, granule exocytosis, and outward trafficking of recycling endosomes to the plasma membrane. We used fluorescein-conjugated cholera toxin B (FITC-CTxB) to label GM(1) in recycling endsomes and to monitor antigen-stimulated trafficking to the plasma membrane in both fluorimeter and imaging-based assays. We find that the sphingosine derivatives D-sphingosine and N,N'-dimethylsphingosine effectively inhibit this outward trafficking response, whereas a quarternary ammonium derivative, N,N',N″-trimethylsphingosine, does not inhibit. This pattern of inhibition is also found for Ca(2+) mobilization and secretory lysosomal exocytosis, indicating a general effect on Ca(2+)-dependent signaling processes. This inhibition correlates with the capacity of sphingosine derivatives to flip to the inner leaflet of the plasma membrane that is manifested as changes in plasma membrane-associated FITC-CTxB fluorescence and cytoplasmic pH. Using a fluorescently labeled MARCKS effector domain to monitor plasma membrane-associated polyphosphoinositides, we find that these sphingosine derivatives displace the electrostatic binding of this MARCKS effector domain to the plasma membrane in parallel with their capacity to inhibit Ca(2+)-dependent signaling. Our results support roles for plasma membrane polyphosphoinositides in Ca(2+) signaling and stimulated exocytosis, and they illuminate a mechanism by which D-sphingosine regulates signaling responses in mammalian cells.
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Affiliation(s)
- Norah L Smith
- Department of Chemistry and Chemical Biology; Cornell University; Ithaca, NY USA
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9
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Skolová B, Janůšová B, Zbytovská J, Gooris G, Bouwstra J, Slepička P, Berka P, Roh J, Palát K, Hrabálek A, Vávrová K. Ceramides in the skin lipid membranes: length matters. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:15624-15633. [PMID: 24283654 DOI: 10.1021/la4037474] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Ceramides are essential constituents of the skin barrier that allow humans to live on dry land. Reduced levels of ceramides have been associated with skin diseases, e.g., atopic dermatitis. However, the structural requirements and mechanisms of action of ceramides are not fully understood. Here, we report the effects of ceramide acyl chain length on the permeabilities and biophysics of lipid membranes composed of ceramides (or free sphingosine), fatty acids, cholesterol, and cholesterol sulfate. Short-chain ceramides increased the permeability of the lipid membranes compared to a long-chain ceramide with maxima at 4-6 carbons in the acyl. By a combination of differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, Langmuir monolayers, and atomic force microscopy, we found that the reason for this effect in short ceramides was a lower proportion of tight orthorhombic packing and phase separation of continuous short ceramide-enriched domains with shorter lamellar periodicity compared to native long ceramides. Thus, long acyl chains in ceramides are essential for the formation of tightly packed impermeable lipid lamellae. Moreover, the model skin lipid membranes are a valuable tool to study the relationships between the lipid structure and composition, lipid organization, and the membrane permeability.
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Affiliation(s)
- Barbora Skolová
- Charles University in Prague , Faculty of Pharmacy, Heyrovského 1203, 50005 Hradec Králové, Czech Republic
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10
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Smith NL, Abi Abdallah DS, Butcher BA, Denkers EY, Baird B, Holowka D. Toxoplasma gondii inhibits mast cell degranulation by suppressing phospholipase Cγ-mediated Ca(2+) mobilization. Front Microbiol 2013; 4:179. [PMID: 23847603 PMCID: PMC3701878 DOI: 10.3389/fmicb.2013.00179] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 06/14/2013] [Indexed: 12/21/2022] Open
Abstract
Toxoplasma gondii is well-known to subvert normal immune responses, however, mechanisms are incompletely understood. In particular, its capacity to alter receptor-activated Ca2+-mediated signaling processes has not been well-characterized. In initial experiments, we found evidence that T. gondii infection inhibits Ca2+ responses to fMetLeuPhe in murine macrophages. To further characterize the mechanism of inhibition of Ca2+ mobilization by T. gondii, we used the well-studied RBL mast cell model to probe the capacity of T. gondii to modulate IgE receptor-activated signaling within the first hour of infection. Ca2+ mobilization that occurs via IgE/FcεRI signaling leads to granule exocytosis in mast cells. We found that T. gondii inhibits antigen-stimulated degranulation in infected cells in a strain-independent manner. Under these conditions, we found that cytoplasmic Ca2+ mobilization, particularly antigen-mediated Ca2+ release from intracellular stores, is significantly reduced. Furthermore, stimulation-dependent activation of Syk kinase leading to tyrosine phosphorylation and activation of phospholipase Cγ is inhibited by infection. Therefore, we conclude that inhibitory effects of infection are likely due to parasite-mediated inhibition of the tyrosine kinase signaling cascade that results in reduced hydrolysis of phosphatidylinositol 4,5-bisphosphate. Interestingly, inhibition of IgE/FcεRI signaling persists when tachyzoite invasion is arrested via cytochalasin D treatment, suggesting inhibition is mediated by a parasite-derived factor secreted into the cells during the invasion process. Our study provides direct evidence that immune subversion by T. gondii is initiated concurrently with invasion.
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Affiliation(s)
- Norah L Smith
- Baker Laboratory, Department of Chemistry and Chemical Biology, Cornell University Ithaca, NY, USA
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11
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Age-Related Changes in the Phospholipase D-Dependent Signal Pathway of Insulin in the Rat Neocortex. NEUROPHYSIOLOGY+ 2013. [DOI: 10.1007/s11062-013-9346-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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12
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Russo SB, Ross JS, Cowart LA. Sphingolipids in obesity, type 2 diabetes, and metabolic disease. Handb Exp Pharmacol 2013:373-401. [PMID: 23563667 DOI: 10.1007/978-3-7091-1511-4_19] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Metabolic disease, including obesity and type 2 diabetes, constitutes a major emerging health crisis in Western nations. Although the symptoms and clinical pathology and physiology of these conditions are well understood, the molecular mechanisms underlying the disease process have largely remained obscure. Sphingolipids, a lipid class with both signaling and structural properties, have recently emerged as key players in most major tissues affected by diabetes and are required components in the molecular etiology of this disease. Indeed, sphingolipids have been shown to mediate loss of insulin sensitivity, to promote the characteristic diabetic proinflammatory state, and to induce cell death and dysfunction in important organs such as the pancreas and heart. Furthermore, plasma sphingolipid levels are emerging as potential biomarkers for the decompensation of insulin resistance to frank type 2 diabetes. Despite these discoveries, the roles of specific sphingolipid species and sphingolipid metabolic pathways remain obscure, and newly developed experimental approaches must be employed to elucidate the detailed molecular mechanisms necessary for rational drug development and other clinical applications.
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Affiliation(s)
- S B Russo
- Department of Biochemistry and Molecular Biology, The Medical University of South Carolina, Charleston, SC, USA
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13
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Abstract
There is growing evidence that cell membranes can contain domains with different lipid and protein compositions and with different physical properties. Furthermore, it is increasingly appreciated that sphingolipids play a crucial role in the formation and properties of ordered lipid domains (rafts) in cell membranes. This review describes recent advances in our understanding of ordered membrane domains in both cells and model membranes. In addition, how the structure of sphingolipids influences their ability to participate in the formation of ordered domains, as well as how sphingolipid structure alters ordered domain properties, is described. The diversity of sphingolipid structure is likely to play an important role in modulating the biologically relevant properties of "rafts" in cell membranes.
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14
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Machta BB, Veatch SL, Sethna JP. Critical Casimir forces in cellular membranes. PHYSICAL REVIEW LETTERS 2012; 109:138101. [PMID: 23030121 PMCID: PMC3711834 DOI: 10.1103/physrevlett.109.138101] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Indexed: 05/23/2023]
Abstract
Recent experiments suggest that membranes of living cells are tuned close to a miscibility critical point in the two-dimensional Ising universality class. We propose that one role for this proximity to criticality in live cells is to provide a conduit for relatively long-range critical Casimir forces. Using techniques from conformal field theory we calculate potentials of mean force between membrane bound inclusions mediated by their local interactions with the composition order parameter. We verify these calculations using Monte Carlo simulations where we also compare critical and off-critical results. Our findings suggest that membrane bound proteins experience weak yet long-range forces mediated by critical composition fluctuations in the plasma membranes of living cells.
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Affiliation(s)
- Benjamin B Machta
- Department of Physics, Cornell University, Ithaca, New York 14850, USA
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15
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Babenko NA, Kharchenko VS. Ceramides inhibit phospholipase D-dependent insulin signaling in liver cells of old rats. BIOCHEMISTRY (MOSCOW) 2012; 77:180-6. [DOI: 10.1134/s0006297912020095] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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16
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Role of endothelial dysfunction in modulating the plasma redox homeostasis in visceral leishmaniasis. Biochim Biophys Acta Gen Subj 2011; 1810:652-65. [DOI: 10.1016/j.bbagen.2011.03.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 03/11/2011] [Accepted: 03/31/2011] [Indexed: 01/12/2023]
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17
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Takács M, Bubenyák M, Váradi A, Blazics B, Horváth P, Kökösi J. Synthesis of novel ceramide-like penetration enhancers. Tetrahedron Lett 2011. [DOI: 10.1016/j.tetlet.2011.02.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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18
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Lipid-like sulfoxides and amine oxides as inhibitors of mast cell activation. Eur J Med Chem 2011; 46:2147-51. [PMID: 21421276 DOI: 10.1016/j.ejmech.2011.02.068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 02/21/2011] [Accepted: 02/26/2011] [Indexed: 11/20/2022]
Abstract
The drug miltefosine is a prototypic lipid-like compound thought to modulate membrane environments and thereby indirectly prevent receptor-mediated signaling events. In addition to its primary therapeutic indications in cancer and leishmaniasis, miltefosine has also been shown to block immunoglobulin E receptor-dependent mast cell activation. Miltefosine and other alkylphospholipids that are active in mast cell degranulation assays contain a positively charged nitrogen and a phosphate group that are important for activity. In addition to alkylphospholipids, ceramides are also known to act on membrane environments and inhibit mast cell activation. We have systematically searched a very large compound collection for other lipid-like inhibitors of mast cell activation. Analogs of an initially identified screening hit were synthesized and preliminary SAR information was collected, leading to the identification of sulfoxide and amine oxide containing lipid-like compounds as new inhibitors of mast cell activation. Sulfoxide and amine oxide derivatives were found to be only slightly less active than miltefosine.
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Janůšová B, Zbytovská J, Lorenc P, Vavrysová H, Palát K, Hrabálek A, Vávrová K. Effect of ceramide acyl chain length on skin permeability and thermotropic phase behavior of model stratum corneum lipid membranes. Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1811:129-37. [PMID: 21167310 DOI: 10.1016/j.bbalip.2010.12.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 12/03/2010] [Accepted: 12/06/2010] [Indexed: 11/16/2022]
Abstract
Stratum corneum ceramides play an essential role in the barrier properties of skin. However, their structure-activity relationships are poorly understood. We investigated the effects of acyl chain length in the non-hydroxy acyl sphingosine type (NS) ceramides on the skin permeability and their thermotropic phase behavior. Neither the long- to medium-chain ceramides (8-24 C) nor free sphingosine produced any changes of the skin barrier function. In contrast, the short-chain ceramides decreased skin electrical impedance and increased skin permeability for two marker drugs, theophylline and indomethacin, with maxima in the 4-6C acyl ceramides. The thermotropic phase behavior of pure ceramides and model stratum corneum lipid membranes composed of ceramide/lignoceric acid/cholesterol/cholesterol sulfate was studied by differential scanning calorimetry and infrared spectroscopy. Differences in thermotropic phase behavior of these lipids were found: those ceramides that had the greatest impact on the skin barrier properties displayed the lowest phase transitions and formed the least dense model stratum corneum lipid membranes at 32°C. In conclusion, the long hydrophobic chains in the NS-type ceramides are essential for maintaining the skin barrier function. However, this ability is not shared by their short-chain counterparts despite their having the same polar head structure and hydrogen bonding ability.
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Affiliation(s)
- Barbora Janůšová
- Department of Inorganic and Organic Chemistry, Charles University in Prague, Hradec Králové, Czech Republic
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20
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Karman J, Tedstone JL, Gumlaw NK, Zhu Y, Yew N, Siegel C, Guo S, Siwkowski A, Ruzek M, Jiang C, Cheng SH. Reducing glycosphingolipid biosynthesis in airway cells partially ameliorates disease manifestations in a mouse model of asthma. Int Immunol 2010; 22:593-603. [PMID: 20497953 DOI: 10.1093/intimm/dxq044] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Lipid rafts reportedly play an important role in modulating the activation of mast cells and granulocytes, the primary effector cells of airway hyperresponsiveness and asthma. Activation is mediated through resident signaling molecules whose activity, in part, may be modulated by the composition of glycosphingolipids (GSLs) in membrane rafts. In this study, we evaluated the impact of inhibiting GSL biosynthesis in mast cells and in the ovalbumin (OVA)-induced mouse model of asthma using either a small molecule inhibitor or anti-sense oligonucleotides (ASOs) directed against specific enzymes in the GSL pathway. Lowering GSL levels in mast cells through inhibition of glucosylceramide synthase (GCS) reduced phosphorylation of Syk tyrosine kinase and phospholipase C gamma 2 (PLC-gamma2) as well as cytoplasmic Ca(2+) levels. Modulating these intracellular signaling events also resulted in a significant decrease in mast cell degranulation. Primary mast cells isolated from a GM3 synthase (GM3S) knockout mouse exhibited suppressed activation-induced degranulation activity further supporting a role of GSLs in this process. In previously OVA-sensitized mice, intra-nasal administration of ASOs to GCS, GM3S or lactosylceramide synthase (LCS) significantly suppressed metacholine-induced airway hyperresponsiveness and pulmonary inflammation to a subsequent local challenge with OVA. However, administration of the ASOs into mice that had been sensitized and locally challenged with the allergen did not abate the consequent pulmonary inflammatory sequelae. These results suggest that GSLs contribute to the initiation phase of the pathogenesis of airway hyperreactivity and asthma and lowering GSL levels may offer a novel strategy to modulate these manifestations.
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Affiliation(s)
- Jozsef Karman
- Genzyme Corporation, 49 New York Avenue, Framingham, MA 01701, USA.
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Fifadara NH, Beer F, Ono S, Ono SJ. Interaction between activated chemokine receptor 1 and FcepsilonRI at membrane rafts promotes communication and F-actin-rich cytoneme extensions between mast cells. Int Immunol 2010; 22:113-28. [PMID: 20173038 DOI: 10.1093/intimm/dxp118] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Chemokines play important regulatory roles in immunity, but their contributions to mast cell function remain poorly understood. We examined the effects of FcepsilonRI-chemokine receptor (CCR) 1 co-stimulation on receptor localization and cellular morphology of bone marrow-derived mast cells. Whereas FcepsilonRI and CCR1 co-localized at the plasma membrane in unsensitized cells, sensitization with IgE promoted internalization of CCR1 molecules. Co-stimulation of FcepsilonRI and CCR1 with antigen and macrophage inflammatory protein-1alpha was more effective than FcepsilonRI stimulation alone in causing leading edge formation, flattened morphology, membrane ruffles and ganglioside (GM1(+)) lipid mediator release. Co-stimulation resulted in phalloidin-positive cytoneme-like cellular extensions, also known as tunneling nanotubes, which originated at points of calcium accumulation. This is the first report of cytoneme formation by mast cells. To determine the importance of lipid rafts for mast cell function, the cells were cholesterol depleted. Cholesterol depletion enhanced degranulation in resting, sensitized and co-stimulated cells, but not in FcepsilonRI-cross-linked cells, and inhibited formation of filamentous actin(+) cytonemes but not GM1(+) cytonemes. Treatment with latrunculin A to sequester globular-actin abolished cytoneme formation. The cytonemes may participate in intercellular communication during allergic and inflammatory responses, and their presence in the co-stimulated mast cells suggests new roles for CCRs in immunopathology.
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Affiliation(s)
- Nimita H Fifadara
- Dobbs Ocular Immunology Laboratories, Department of Ophthalmology, Emory Eye Center, Emory University School of Medicine, Atlanta, GA 30322, USA.
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23
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Phospholipase D modulation by ceramide in senescence. Mol Cell Biochem 2009; 337:153-8. [DOI: 10.1007/s11010-009-0294-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Accepted: 10/08/2009] [Indexed: 11/27/2022]
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Lisboa FA, Peng Z, Combs CA, Beaven MA. Phospholipase d promotes lipid microdomain-associated signaling events in mast cells. THE JOURNAL OF IMMUNOLOGY 2009; 183:5104-12. [PMID: 19794068 DOI: 10.4049/jimmunol.0802728] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Initial IgE-dependent signaling events are associated with detergent-resistant membrane microdomains. Following Ag stimulation, the IgE-receptor (Fc(epsilon)RI ) accumulates within these domains. This facilitates the phosphorylation of Fc(epsilon)RI subunits by the Src kinase, Lyn, and the interaction with adaptor proteins, such as the linker for activation of T cells. Among the phospholipases (PL) subsequently activated, PLD is of interest because of its presence in lipid microdomains and the possibility that its product, phosphatidic acid, may regulate signal transduction and membrane trafficking. We find that in Ag-stimulated RBL-2H3 mast cells, the association of Fc(epsilon)RI with detergent-resistant membrane fractions is inhibited by 1-butanol, which subverts production of phosphatidic acid to the biologically inert phosphatidylbutanol. Furthermore, the knockdown of PLD2, and to a lesser extent PLD1 with small inhibitory RNAs, also suppressed the accumulation of Fc(epsilon)RI and Lyn in these fractions as well as the phosphorylation of Src kinases, Fc(epsilon)RI , linker for activation of T cells, and degranulation. These effects were accompanied by changes in distribution of the lipid microdomain component, ganglioside 1, in the plasma membrane as determined by binding of fluorescent-tagged cholera toxin B subunit and confocal microscopy in live cells. Collectively, these findings suggest that PLD activity plays an important role in promoting IgE-dependent signaling events within lipid microdomains in mast cells.
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Affiliation(s)
- Felipe A Lisboa
- Laboratory of Molecular Immunology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1760, USA
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Pakkanen K, Salonen E, Mäkelä AR, Oker-Blom C, Vattulainen I, Vuento M. Desipramine induces disorder in cholesterol-rich membranes: implications for viral trafficking. Phys Biol 2009; 6:046004. [DOI: 10.1088/1478-3975/6/4/046004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Psychosine accumulates in membrane microdomains in the brain of krabbe patients, disrupting the raft architecture. J Neurosci 2009; 29:6068-77. [PMID: 19439584 DOI: 10.1523/jneurosci.5597-08.2009] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Lipid rafts (LRs) are membrane realms characterized by high concentrations of cholesterol and sphingolipids. Often, they are portrayed as scaffolds on which many different signaling molecules can assemble their cascades. The idea of rafts as scaffolds is garnering significant attention as the consequences of LR disruption have been shown to be manifest in multiple signaling pathways. In this study, LRs in the brain of the twitcher (TWI) mouse, a bona-fide model for infant variants of human globoid cell leukodystrophy or Krabbe disease, were investigated. This mouse has deficient activity of GALC (beta-galactosylceramidase) that leads to a progressive accumulation of some galactosyl-sphingolipids in the brain. We hypothesized that the accumulation of psychosine (galactosyl-sphingosine) in the TWI CNS may result in the disruption of rafts in different cell populations such as neurons and oligodendrocytes, both cellular targets during disease. In this communication, we demonstrate that psychosine specifically accumulates in LRs in the TWI brain and sciatic nerve and in samples from brains of human Krabbe patients. It is also shown that this accumulation is accompanied by an increase in cholesterol in these domains and changes in the distribution of the LR markers flotillin-2 and caveolin-1. Finally, we show evidence that this phenomenon may provide a mechanism by which psychosine can exert its known inhibitory effect on protein kinase C. This study provides a previously undescribed biophysical aspect for the mechanism of pathogenesis in Krabbe disease.
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Heakal Y, Kester M. Nanoliposomal short-chain ceramide inhibits agonist-dependent translocation of neurotensin receptor 1 to structured membrane microdomains in breast cancer cells. Mol Cancer Res 2009; 7:724-34. [PMID: 19435815 DOI: 10.1158/1541-7786.mcr-08-0322] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Neurotensin (NTS) receptor 1 (NTSR1) is a G protein-coupled receptor that has been recently identified as a mediator of tumorigenicity and metastasis. NTSR1, as well as its endogenous ligand, NTS, are coexpressed in several breast cancer cell lines and breast cancer tumor samples but not in normal breast tissue. We have previously published that ceramide mimetics could inhibit breast cancer growth in vitro and in vivo. Thus, understanding the biochemical and biophysical regulation of NTSR1 by ceramide can help further define NTSR1 as a novel target in breast cancer. Our results show that nanoliposomal formulations of ceramide inhibit NTSR1-mediated MDA-MB-231 breast cancer progression (mitogenesis, migration, and matrix metalloproteinase-9 activity). In addition, liposomal ceramide inhibited NTSR1-mediated, but not phorbol 12-myristate 13-acetate-mediated, activation of the mitogen-activated protein kinase pathway. Mechanistically, nanoliposomal short-chain ceramide reduces NTSR1 interaction with Galphaq/11 subunits within structured membrane microdomains, consistent with diminished NTS-induced translocation of NTSR1 into membrane microdomains. Collectively, our findings suggest that exogenous short-chain ceramide has the potential to be used as an adjuvant therapy to inhibit NTS-dependent breast cancer progression.
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Affiliation(s)
- Yasser Heakal
- Department of Pharmacology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA
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Fluorescence correlation spectroscopy in membrane structure elucidation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:225-33. [DOI: 10.1016/j.bbamem.2008.08.013] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 08/12/2008] [Accepted: 08/21/2008] [Indexed: 11/18/2022]
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Carrer DC, Schmidt AW, Knölker HJ, Schwille P. Membrane domain-disrupting effects of 4-substitued cholesterol derivatives. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:8807-8812. [PMID: 18656973 DOI: 10.1021/la801471e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A wide range of cellular functions are thought to be regulated not only by the activity of membrane proteins, but also by the local membrane organization, including domains of specific lipid composition. Thus, molecules and drugs targeting and disrupting this lipid pattern, particularly of the plasma membrane, will not only help to investigate the role of membrane domains in cell biology, but might also be interesting candidates for therapy. We have identified three 4-substituted cholesterol derivatives that are able to induce a domain-disrupting effect in model membranes. When applied to giant unilamellar vesicles displaying liquid-ordered-liquid-disordered phase coexistence, extensive reorganization of the membrane can be observed, such as the budding of membrane tubules or changes in the geometry of the domains, to the point of complete abolition of phase separation. In this case, the resulting membranes display a fluidity intermediate between those of liquid-disordered and liquid-ordered phases.
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Affiliation(s)
- Dolores C Carrer
- Biophysics Group, BIOTEC, TU Dresden, Tatzberg 47-51, Dresden, Germany
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30
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Efendiev R, Budu CE, Bertorello AM, Pedemonte CH. G-protein-coupled receptor-mediated traffic of Na,K-ATPase to the plasma membrane requires the binding of adaptor protein 1 to a Tyr-255-based sequence in the alpha-subunit. J Biol Chem 2008; 283:17561-7. [PMID: 18420589 PMCID: PMC2427321 DOI: 10.1074/jbc.m709260200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 04/15/2008] [Indexed: 11/06/2022] Open
Abstract
Motion of integral membrane proteins to the plasma membrane in response to G-protein-coupled receptor signals requires selective cargo recognition motifs that bind adaptor protein 1 and clathrin. Angiotensin II, through the activation of AT1 receptors, promotes the recruitment to the plasma membrane of Na,K-ATPase molecules from intracellular compartments. We present evidence to demonstrate that a tyrosine-based sequence (IVVY-255) present within the Na,K-ATPase alpha1-subunit is involved in the binding of adaptor protein 1. Mutation of Tyr-255 to a phenylalanine residue in the Na,K-ATPase alpha1-subunit greatly reduces the angiotensin II-dependent activation of Na,K-ATPase, recruitment of Na,K-ATPase molecules to the plasma membrane, and association of adaptor protein 1 with Na,K-ATPase alpha1-subunit molecules. To determine protein-protein interaction, we used fluorescence resonance energy transfer between fluorophores attached to the Na,K-ATPase alpha1-subunit and adaptor protein 1. Although angiotensin II activation of AT1 receptors induces a significant increase in the level of fluorescence resonance energy transfer between the two molecules, this effect was blunted in cells expressing the Tyr-255 mutant. Thus, results from different methods and techniques suggest that the Tyr-255-based sequence within the NKA alpha1-subunit is the site of adaptor protein 1 binding in response to the G-protein-coupled receptor signals produced by angiotensin II binding to AT1 receptors.
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Affiliation(s)
- Riad Efendiev
- College of Pharmacy, University of Houston, Houston, Texas 77204, USA.
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Gallegos CE, Pediconi MF, Barrantes FJ. Ceramides modulate cell-surface acetylcholine receptor levels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:917-30. [PMID: 18023270 DOI: 10.1016/j.bbamem.2007.10.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 09/25/2007] [Accepted: 10/19/2007] [Indexed: 10/22/2022]
Abstract
The effects of ceramides (Cer) on the trafficking of the nicotinic acetylcholine receptor (AChR) to the plasma membrane were studied in CHO-K1/A5 cells, a clonal cell line that heterologously expresses the adult murine form of the receptor. When cells were incubated with short- (C6-Cer) or long- (brain-Cer) chain Cer at low concentrations, an increase in the number of cell-surface AChRs was observed concomitant with a decrease in intracellular receptor levels. The alteration in AChR distribution by low Cer treatment does not appear to be a general mechanism since the surface expression of the green fluorescent protein derivative of the vesicular stomatitis virus protein (VSVG-GFP) was not affected. High Cer concentrations caused the opposite effects, decreasing the number of cell-surface AChRs, which exhibited higher affinity for [125I]-alpha-bungarotoxin, and increasing the intracellular pool, which colocalized with trans-Golgi/TGN specific markers. The generation of endogenous Cer by sphingomyelinase treatment also decreased cell-surface AChR levels. These effects do not involve protein kinase C zeta or protein phosphatase 2A activation. Taken together, the results indicate that Cer modulate trafficking of AChRs to and stability at the cell surface.
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Affiliation(s)
- C E Gallegos
- UNESCO Chair of Biophysics and Molecular Neurobiology and Instituto de Investigaciones Bioquímicas de Bahía Blanca, Argentina
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32
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Chiba N, Masuda A, Yoshikai Y, Matsuguchi T. Ceramide inhibits LPS-induced production of IL-5, IL-10, and IL-13 from mast cells. J Cell Physiol 2007; 213:126-36. [PMID: 17458900 DOI: 10.1002/jcp.21101] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Mast cells are central regulators of allergic inflammation through production of various chemical mediators and cytokines. Bacterial infection occasionally worsens allergic inflammation. Although the exact mechanism of this phenomenon remains unclear, we have previously reported that LPS stimulates mast cells to produce not only pro-inflammatory cytokines, such as IL-6 and TNF-alpha, but also Th2-type cytokines, such as IL-5 and IL-13, and a regulatory cytokine, IL-10. In the present study, we have studied the effect of ceramide on LPS-mediated cytokine production from mast cells, as ceramide modulates various cellular functions in many cell types. Administration of cell-permeable C8 ceramide reduced production of IL-5, IL-10, and IL-13 from LPS-stimulated mouse bone marrow-derived mast cells (BMMCs) apparently through transcriptional inhibition, but did not affect IL-6 or TNF-alpha production. Consistently, LPS-stimulated production of IL-5, IL-10, and IL-13 from BMMCs is significantly enhanced in the presence of fumonisin B1, a de novo ceramide synthesis inhibitor. Interestingly, the same C8 ceramide treatment showed opposite effects on cytokine production from LPS-stimulated macrophages, reducing IL-6 and TNF-alpha while not affecting IL-10 production. C8 ceramide pretreatment significantly reduced LPS-induced Akt phosphorylation in BMMCs, but not in macrophages. Furthermore, pretreatment of BMMCs by wortmannin, a specific inhibitor of PI3 kinase, inhibited LPS-stimulated expression of IL-5, IL-10, and IL-13, but not that of TNF-alpha or IL-6. Thus, ceramide appeared to down-regulate LPS-stimulated production of IL-5, IL-10, and IL-13 from mast cells by inhibiting PI3 kinase-Akt pathway in a cell type-specific manner.
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Affiliation(s)
- Norika Chiba
- Division of Host Defense, Center for Neural Disease and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
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Holowka D, Sil D, Torigoe C, Baird B. Insights into immunoglobulin E receptor signaling from structurally defined ligands. Immunol Rev 2007; 217:269-79. [PMID: 17498065 DOI: 10.1111/j.1600-065x.2007.00517.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The asymmetrical structure of bent immunoglobulin E (IgE) bound to its high-affinity receptor, Fc epsilon RI, suggests a possible role for this configuration in the regulation of signaling mediated by cross-linking of Fc epsilon RI on the surface of mast cells and basophils. Indeed, the presence of bound IgE strongly influences the capacity of cross-linked Fc epsilon RI dimers to trigger mast cell degranulation, implicating orientational constraints by bound IgE. Bivalent ligands that cross-link by binding to bivalent IgE can form linear and cyclic chains of IgE/Fc epsilon RI complexes, and these exhibit only limited capacity to stimulate downstream signaling and degranulation, whereas structurally analogous trivalent ligands, which can form branched networks of cross-linked IgE/Fc epsilon RI complexes, are more effective at cell activation. Long bivalent ligands with flexible spacers can form intramolecular cross-links with IgE, and these stable 1:1 complexes are very potent inhibitors of mast cell degranulation stimulated by multivalent antigen. In contrast, trivalent ligands with rigid double-stranded DNA spacers effectively stimulate degranulation responses in a length-dependent manner, providing direct evidence for receptor transphosphorylation as a key step in the mechanism of signaling by Fc epsilon RI. Thus, studies with chemically defined oligovalent ligands show important features of IgE receptor cross-linking that regulate signaling, leading to mast cell activation.
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Affiliation(s)
- David Holowka
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA.
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Munday AD, López JA. Posttranslational protein palmitoylation: promoting platelet purpose. Arterioscler Thromb Vasc Biol 2007; 27:1496-9. [PMID: 17581830 DOI: 10.1161/atvbaha.106.136226] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Chiantia S, Kahya N, Schwille P. Raft domain reorganization driven by short- and long-chain ceramide: a combined AFM and FCS study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:7659-65. [PMID: 17564472 DOI: 10.1021/la7010919] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Naturally occurring long-chain ceramides (Cer) are known to alter the lateral organization of biological membranes. In particular, they produce alterations of microdomains that are involved in several cellular processes, ranging from apoptosis to immune response. In order to induce similar biological effects, short-chain Cer are extensively used in in vivo experiments to replace their long-chain analogues. In this work, we used the combined approach of atomic force microscopy (AFM) and fluorescence correlation spectroscopy (FCS) to investigate the effect of Cer chain length in lipid bilayers composed of sphingomyelin, dioleoyl-phosphatidylcholine, and cholesterol. Our results show that only long-chain Cer, like C18 and C16, are able to segregate from the liquid-ordered phase, forming separate Cer-enriched domains. Conversely, short-chain Cer do not form a separate phase but alter the physical properties of the liquid-ordered domains, decreasing their stability and viscosity and perturbing the lipid packing. These differences may contribute to the explanation of the different physiological effects that are often observed for the long- and short-chain Cer.
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Affiliation(s)
- Salvatore Chiantia
- Biophysics group, Biotechnologisches Zentrum (BIOTEC), Technische Universität, Tatzberg 47-51, 01307, Dresden, Germany
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Megha, Sawatzki P, Kolter T, Bittman R, London E. Effect of ceramide N-acyl chain and polar headgroup structure on the properties of ordered lipid domains (lipid rafts). BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:2205-12. [PMID: 17574203 DOI: 10.1016/j.bbamem.2007.05.007] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 04/30/2007] [Accepted: 05/07/2007] [Indexed: 01/10/2023]
Abstract
Ceramides are sphingolipids that greatly stabilize ordered membrane domains (lipid rafts), and displace cholesterol from them. Ceramide-rich rafts have been implicated in diverse biological processes. Because ceramide analogues have been useful for probing the biological function of ceramide, and may have biomedical applications, it is important to characterize how ceramide structure affects membrane properties, including lipid raft stability and composition. In this report, fluorescence quenching assays were used to evaluate the effect of analogues of ceramide with different N-acyl chains or different sphingoid backbones on raft stability and sterol content. The effect of replacing 18 mol% of sphingomyelin (SM) with ceramide in vesicles composed of a 1:1 (mol:mol) mixture of SM and dioleoylphosphatidylcholine (DOPC), with or without 25 mol% sterol, was examined. In the absence of sterol, the thermal stability of the SM-rich ordered domains increased with ceramide N-acyl chain length in the order C2:0 approximately C6:0 approximately C8:0<no ceramide<C12:0<C16:0. In vesicles containing 25 mol% cholesterol (1:1:0.66 sphingolipid:DOPC:cholesterol), the dependence of raft stability on ceramide N-acyl chain length increased in the order C8:0 approximately C6:0<C2:0<C12:0 approximately no ceramide<C16:0. We also studied the stability of lipid rafts in the presence of N-lauroyl- and N-palmitoylsphingosine analogues containing altered structures in or near the polar portion of the sphingoid base. In almost all cases, the analogues stabilized rafts to about the same degree as a normal ceramide containing the same acyl chain. The only exception was N-palmitoyl-4D-ribophytosphingosine, which was very strongly raft-stabilizing. We conclude that variations in sphingoid base structure induce only insignificant changes in raft properties. N-Lauroyl and N-palmitoylsphingosine and their analogues displaced sterol from rafts to a significant degree. Both C12:0 and C16:0 analogues of ceramide may be good mimics of natural ceramide, and useful for cellular studies in which maintenance of the normal physical properties of ceramide are important.
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Affiliation(s)
- Megha
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
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Adachi T, Sato C, Kitajima K. Membrane microdomain formation is crucial in epiboly during gastrulation of medaka. Biochem Biophys Res Commun 2007; 358:848-53. [PMID: 17511962 DOI: 10.1016/j.bbrc.2007.04.197] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Accepted: 04/30/2007] [Indexed: 10/23/2022]
Abstract
Membrane microdomain (microdomain) was isolated from early gastrula embryos. The isolated microdomain was characterized by enrichment of cholesterol and sphingomyelin, and by the presence of huge glycoproteins containing Lewis X structure. Importance of the microdomain in the progress of epiboly was assessed using methyl beta-cyclodextrin (MBCD) and C2-ceramide that disrupt microdomains through different mechanisms. Both reagents efficiently disrupted the microdomain structure and concomitantly impaired epiboly. Interestingly, when embryos pretreated with MBCD, a cholesterol-binding molecule, were exogenously supplemented with cholesterol, the embryos underwent not only reconstitution of the microdomain, but also complete restoration to the normal epiboly. Thus, normal or impaired development is reversibly controlled by the cholesterol-dependent formation or disruption of microdomains. The most typical phenotype of the microdomain-disrupted embryos is detachment of cells from the blastoderm, suggesting that a major contribution of microdomains to epiboly is cell adhesion of blastodermal cells.
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Affiliation(s)
- Tomoko Adachi
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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Sengupta P, Holowka D, Baird B. Fluorescence resonance energy transfer between lipid probes detects nanoscopic heterogeneity in the plasma membrane of live cells. Biophys J 2007; 92:3564-74. [PMID: 17325019 PMCID: PMC1853158 DOI: 10.1529/biophysj.106.094730] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fluorescence resonance energy transfer (FRET) between matched carbocyanine lipid analogs in the plasma membrane outer leaflet of RBL mast cells was used to investigate lateral distributions of lipids and to develop a general method for quantitative measurements of lipid heterogeneity in live cell membranes. FRET measured as fluorescence quenching of long-chain donor probes such as DiO-C18 is greater with long-chain, saturated acceptor probes such as DiI-C16 than with unsaturated or shorter-chain acceptors with the same chromophoric headgroup compared at identical concentrations. FRET measurements between these lipid probes in model membranes support the conclusion that differential donor quenching is not caused by nonideal mixing or spectroscopic differences. Sucrose gradient analysis of plasma membrane-labeled, Triton X-100-lysed cells shows that proximity measured by FRET correlates with the extent of lipid probe partitioning into detergent-resistant membranes. FRET between DiO-C16 and DiI-C16 is sensitive to cholesterol depletion and disruption of liquid order (Lo) by short-chain ceramides, and it is enhanced by cross linking of Lo-associated proteins. Consistent results are obtained when homo-FRET is measured by decreased fluorescence anisotropy of DiI-C16. These results support the existence of nanometer-scale Lo/liquid disorder heterogeneity of lipids in the outer leaflet of the plasma membrane in live cells.
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Affiliation(s)
- Prabuddha Sengupta
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, USA
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Silvius JR, Nabi IR. Fluorescence-quenching and resonance energy transfer studies of lipid microdomains in model and biological membranes. Mol Membr Biol 2006; 23:5-16. [PMID: 16611577 DOI: 10.1080/09687860500473002] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Measurements of contact-dependent fluorescence quenching and of fluorescence resonance energy transfer (FRET) within bilayers provide information concerning the spatial relationships between molecules on distance scales of a few nm or up a few tens of nm, respectively, and are therefore well suited to detect the presence and composition of membrane microdomains. As described in this review, techniques based on fluorescence quenching and FRET have been used to demonstrate the formation of nanoscale liquid-ordered domains in cholesterol-containing model membranes under physiological conditions, and to investigate the structural features of lipids and proteins that influence their partitioning between liquid-ordered and liquid-disordered domains. FRET-based methods have also been used to test for the presence of 'raft' microdomains in the plasma membranes of mammalian cells. We discuss the sometimes divergent findings of these studies, possible modifications to the 'raft hypothesis' suggested by studies using FRET and other techniques, and the further potential of FRET-based methods to test and to refine current models of the nature and organization of membrane microdomains.
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Affiliation(s)
- John R Silvius
- Department of Biochemistry, McGill University, Montréal, Québec, Canada.
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Preininger AM, Henage LG, Oldham WM, Yoon EJ, Hamm HE, Brown HA. Direct Modulation of Phospholipase D Activity by Gβγ. Mol Pharmacol 2006; 70:311-8. [PMID: 16638972 DOI: 10.1124/mol.105.021451] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Phospholipase D-mediated hydrolysis of phosphatidylcholine is stimulated by protein kinase C and the monomeric G proteins Arf, RhoA, Cdc42, and Rac1, resulting in complex regulation of this enzyme. Using purified proteins, we have identified a novel inhibitor of phospholipase D activity, Gbetagamma subunits of heterotrimeric G proteins. G protein-coupled receptor activation alters affinity between Galpha and Gbetagamma subunits, allowing subsequent interaction with distinct effectors. Gbeta1gamma1 inhibited phospholipase D1 and phospholipase D2 activity, and both Gbeta1gamma1 and Gbeta1gamma2 inhibited stimulated phospholipase D1 activity in a dosedependent manner in reconstitution assays. Reconstitution assays suggest this interaction occurs through the amino terminus of phospholipase D, because Gbeta1gamma1 is unable to inhibit an amino-terminally truncated phospholipase D construct, PLD1.d311, which like full-length phospholipase D isoforms, requires phosphatidylinositol-4,5-bisphosphate for activity. Furthermore, a truncated protein consisting of the amino-terminal region of phospholipase D containing the phox/pleckstrin homology domains was found to interact with Gbeta1gamma1, unlike the PLD1.d311 recombinant protein, which lacks this domain. In vivo, expressed recombinant Gbeta1gamma2 was also found to inhibit phospholipase D activity under basal and stimulated conditions in MDA-MB-231 cells, which natively express both phospholipase D1 and phospholipase D2. These data demonstrate that Gbetagamma directly regulates phospholipase D activity in vitro and suggest a novel mechanism to negatively regulate phospholipase D signaling in vivo.
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Affiliation(s)
- A M Preininger
- Department of Pharmacology: 442 RRB, Vanderbilt University School of Medicine, 23rd Ave. South and Pierce, Nashville, TN 37232-6600, USA
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Gombos I, Kiss E, Detre C, László G, Matkó J. Cholesterol and sphingolipids as lipid organizers of the immune cells’ plasma membrane: Their impact on the functions of MHC molecules, effector T-lymphocytes and T-cell death. Immunol Lett 2006; 104:59-69. [PMID: 16388855 DOI: 10.1016/j.imlet.2005.11.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Revised: 11/20/2005] [Accepted: 11/20/2005] [Indexed: 12/11/2022]
Abstract
The possible regulatory mechanisms by which glycosphingolipid- and cholesterol-rich membrane microdomains, caveolar and non-caveolar lipid rafts, control the immune response are continuously expanding. In the present overview we will focus on how these membrane-organizing lipids are involved, in collaboration with tetraspanin proteins, in the formation of distinct MHC-I and MHC-II microdomains at the cell surface and will analyze the possible roles of MHC compartmentation in the processes of antigen presentation and regulation of various stages of the cellular immune response. Some basic, lipid raft- and tetraspan mediated mechanisms involved in the formation and function of immunological synapses between various APCs and T-cells will also be discussed. Finally, a new aspect of immune regulation by sphingolipids will be briefly described, namely how can the death or stress signals, leading to ceramide accumulation, result in raft-associated regulatory platforms controlling cell death or antigen-induced, TCRmediated signaling of T-lymphocytes. The influence of these signals and their cross-talk on the fate (death or survival) of T-cells and the outcome of T-cell response will also be discussed.
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Affiliation(s)
- Imre Gombos
- Institute of Biology, Department of Immunology, Eötvös Lorand University, Budapest, Hungary
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Sinha Roy S, Mukherjee S, Kabir S, Rajaratnam V, Smith M, Das SK. Inhibition of cholinephosphotransferase activity in lung injury induced by 2-chloroethyl ethyl sulfide, a mustard analog. J Biochem Mol Toxicol 2006; 19:289-97. [PMID: 16292752 DOI: 10.1002/jbt.20092] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Exposure to mustard gas causes inflammatory lung diseases including acute respiratory distress syndrome (ARDS). A defect in the lung surfactant system has been implicated as a cause of ARDS. A major component of lung surfactant is dipalmitoyl phosphatidylcholine (DPPC) and the major pathway for its synthesis is the cytidine diphosphocholine (CDP-choline) pathway. It is not known whether the ARDS induced by mustard gas is mediated by its direct effects on some of the enzymes in the CDP-choline pathway. In the present study we investigated whether mustard gas exposure modulates the activity of cholinephosphotransferase (CPT) the terminal enzyme by CDP-choline pathway. Adult guinea pigs were intratracheally infused with single doses of 2-chloroethyl ethyl sulfide (CEES) (0.5 mg/kg b.wt. in ethanol). Control animals were injected with vehicles only. The animals were sacrificed at different time and the lungs were removed after perfusion with physiological saline. CPT activity increased steadily up to 4 h and then decreased at 6 h and stabilized at 7 days in both mitochondria and microsomes. To determine the dose-dependent effect of CEES on CPT activity we varied the doses of CEES (0.5-6.0 mg/kg b.wt.) and sacrificed the animals at 1 h and 4 h. CPT activity showed a dose-dependent increase of up to 2.0 mg/kg b.wt. of CEES in both mitochondria and microsomes then decreased at 4.0 mg/kg b.wt. For further studies we used a fixed single dose of CEES (2.0 mg/kg b.wt.) and fixed exposure time (7 days). Lung injury was determined by measuring the leakage of iodinated-bovine serum albumin into lung tissue and expressed as the permeability index. CEES exposure (2.0 mg/kg b.wt. for 7 days) caused a significant decrease of both CPT gene expression (approximately 1.7-fold) and activity (approximately 1.5-fold) in the lung. This decrease in CPT activity was not associated with any mutation of the CPT gene. Previously we reported that CEES infusion increased the production of ceramides which are known to modulate PC synthesis. To determine whether ceramides affect microsomal CPT activity the lung microsomal fraction was incubated with different concentrations of C(2)-ceramide prior to CPT assay. CPT activity decreased significantly with increasing dose and time. The present study indicates that CEES causes lung injury and significantly decreases CPT gene expression and activity. This decrease in CPT activity was not associated with any mutation of the CPT gene is probably mediated by accumulation of ceramides. CEES induced ceramide accumulation may thus play an important role in the development of ARDS by modulating CPT enzyme.
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Affiliation(s)
- Somdutta Sinha Roy
- Department of Biochemistry, Meharry Medical College, 1005 David Todd Blvd, Nashville, TN 37208, USA
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Laulagnier K, Vincent-Schneider H, Hamdi S, Subra C, Lankar D, Record M. Characterization of exosome subpopulations from RBL-2H3 cells using fluorescent lipids. Blood Cells Mol Dis 2006; 35:116-21. [PMID: 16023874 DOI: 10.1016/j.bcmd.2005.05.010] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2005] [Accepted: 05/20/2005] [Indexed: 11/17/2022]
Abstract
Fluorescent lipid probes were used to track lipid trafficking between parent RBL cells and exosomes. We have checked the intracellular labeling of exosomes ("in vivo labeling") from parent cell incubated with either Bodipy-Cer, Bodipy-PC, or NBD-PC. Bodipy-PC labeled equally cells and exosomes, whereas Bodipy-Cer, a Golgi marker, was enriched in exosomes. Golgi membranes participated effectively in exosome biogenesis since cell incubation with brefeldin A leads to a modified phospholipid/protein ratio in exosomes. At the opposite, NBD-PC, a plasma membrane marker weakly labeled exosome membranes. Sorting of subpopulations indicated that the MHC-II containing exosomes were enriched in Bodipy-PC, whereas tetraspanin(CD 63 or CD81)-containing exosomes are essentially labeled with Bodipy-Cer and Bodipy-PC. These results indicated that RBL released two main subpopulations of exosomes that can be discriminated by their protein and lipid contents. When the bulk of exosomes was labeled after their purification ("in vitro labeling") with either of the above-mentioned lipid probes, the Bodipy-Cer was the only one to incorporate noticeably in all the subpopulations, indicating that the previous results obtained during "in vivo labeling" monitored real intracellular lipid trafficking between organelles and exosomes. Bodipy-Cer was further used as a tool to measure the respective amounts of each subpopulations. CD63, MHC II, and CD81-containing exosomes accounted for 47%, 32%, and 21%, respectively, of total exosomes.
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Affiliation(s)
- K Laulagnier
- INSERM U563, Département Lipoprotéines et Médiateurs Lipidiques, CHU Purpan, 31024 Toulouse Cedex 03, France
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Holowka D, Gosse JA, Hammond AT, Han X, Sengupta P, Smith NL, Wagenknecht-Wiesner A, Wu M, Young RM, Baird B. Lipid segregation and IgE receptor signaling: A decade of progress. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1746:252-9. [PMID: 16054713 DOI: 10.1016/j.bbamcr.2005.06.007] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Revised: 06/11/2005] [Accepted: 06/15/2005] [Indexed: 11/25/2022]
Abstract
Recent work to characterize the roles of lipid segregation in IgE receptor signaling has revealed a mechanism by which segregation of liquid ordered regions from disordered regions of the plasma membrane results in protection of the Src family kinase Lyn from inactivating dephosphorylation by a transmembrane tyrosine phosphatase. Antigen-mediated crosslinking of IgE receptors drives their association with the liquid ordered regions, commonly called lipid rafts, and this facilitates receptor phosphorylation by active Lyn in the raft environment. Previous work showed that the membrane skeleton coupled to F-actin regulates stimulated receptor phosphorylation and downstream signaling processes, and more recent work implicates cytoskeletal interactions with ordered lipid rafts in this regulation. These and other results provide an emerging view of the complex role of membrane structure in orchestrating signal transduction mediated by immune and other cell surface receptors.
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Affiliation(s)
- David Holowka
- Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory, Ithaca, NY 14853-1301, USA
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Gosse JA, Wagenknecht-Wiesner A, Holowka D, Baird B. Transmembrane sequences are determinants of immunoreceptor signaling. THE JOURNAL OF IMMUNOLOGY 2005; 175:2123-31. [PMID: 16081778 DOI: 10.4049/jimmunol.175.4.2123] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To investigate structural features critical for signal initiation by Ag-stimulated immunoreceptors, we constructed a series of single-chain chimeric receptors that incorporate extracellular human Fc epsilonRIalpha for IgE binding, a variable transmembrane (TM) segment, and the ITAM-containing cytoplasmic tail of the TCR zeta-chain. We find that functional responses mediated by these receptors are strongly dependent on their TM sequences, and these responses are highly correlated to cross-link-dependent association with detergent-resistant lipid rafts. For one chimera designated alpha Fzeta, mutation of a TM cysteine abolishes robust signaling and lipid raft association. In addition, TM disulfide-mediated oligomerization of another chimeric receptor, alpha zetazeta, enhances signaling. These results demonstrate an important role for TM segments in immunoreceptor signaling and a strong correspondence between strength of signaling and cross-link-dependent partitioning into ordered membrane domains.
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Affiliation(s)
- Julie A Gosse
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA
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Olivera A, Rivera J. Sphingolipids and the balancing of immune cell function: lessons from the mast cell. THE JOURNAL OF IMMUNOLOGY 2005; 174:1153-8. [PMID: 15661867 DOI: 10.4049/jimmunol.174.3.1153] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Recent studies reveal that metabolites of sphingomyelin are critically important for initiation and maintenance of diverse aspects of immune cell activation and function. The conversion of sphingomyelin to ceramide, sphingosine, or sphingosine-1-phosphate (S1P) provides interconvertible metabolites with distinct biological activities. Whereas ceramide and sphingosine function to induce apoptosis and to dampen mast cell responsiveness, S1P functions as a chemoattractant and can up-regulate some effector responses. Many of the S1P effects are mediated through S1P receptor family members (S1P(1-5)). S1P(1), which is required for thymocyte emigration and lymphocyte recirculation, is also essential for Ag-induced mast cell chemotaxis, whereas S1P(2) is important for mast cell degranulation. S1P is released to the extracellular milieu by Ag-stimulated mast cells, enhancing inflammatory cell functions. Modulation of S1P receptor expression profiles, and of enzymes involved in sphingolipid metabolism, particularly sphingosine kinases, are key in balancing mast cell and immune cell responses. Current efforts are unraveling the complex underlying mechanisms regulating the sphingolipid pathway. Pharmacological intervention of these key processes may hold promise for controlling unwanted immune responses.
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Affiliation(s)
- Ana Olivera
- Molecular Immunology and Inflammation Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Falluel-Morel A, Aubert N, Vaudry D, Basille M, Fontaine M, Fournier A, Vaudry H, Gonzalez BJ. Opposite regulation of the mitochondrial apoptotic pathway by C2-ceramide and PACAP through a MAP-kinase-dependent mechanism in cerebellar granule cells. J Neurochem 2005; 91:1231-43. [PMID: 15569266 DOI: 10.1111/j.1471-4159.2004.02810.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The sphingomyelin-derived messenger ceramides provoke neuronal apoptosis through caspase-3 activation, while the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) promotes neuronal survival and inhibits caspase-3 activity. However, the mechanisms leading to the opposite regulation of caspase-3 by C2-ceramide and PACAP are currently unknown. Here, we show that PACAP prevents C2-ceramide-induced inhibition of mitochondrial potential and C2-ceramide-evoked cytochrome c release. C2-ceramide stimulated Bax expression, but had no effect on Bcl-2, while PACAP abrogated the action of C2-ceramide on Bax and stimulated Bcl-2 expression. The effects of C2-ceramide and PACAP on Bax and Bcl-2 were blocked, respectively, by the JNK inhibitor L-JNKI1 and the MEK inhibitor U0126. L-JNKI1 prevented the alteration of mitochondria induced by C2-ceramide while U0126 suppressed the protective effect of PACAP against the deleterious action of C2-ceramide on mitochondrial potential. Moreover, L-JNKI1 inhibited the stimulatory effect of C2-ceramide on caspase-9 and -3 and prevented C2-ceramide-induced cell death. U0126 blocked PACAP-induced Bcl-2 expression, abrogated the inhibitory effect of PACAP on ceramide-induced caspase-9 activity, and promoted granule cell death. The present study reveals that C2-ceramide and PACAP exert opposite effects on Bax and Bcl-2 through, respectively, JNK- and ERK-dependent mechanisms. These data indicate that the mitochondrial pathway plays a pivotal role in the pro- and anti-apoptotic effects of C2-ceramide and PACAP.
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Affiliation(s)
- Anthony Falluel-Morel
- European Institute for Peptide Research (IFRMP 23), Laboratory of Cellular and Molecular Neuroendocrinology, University of Rouen, Mont-Saint-Aignan, France
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Horejsí V. Lipid rafts and their roles in T-cell activation. Microbes Infect 2005; 7:310-6. [PMID: 15715974 DOI: 10.1016/j.micinf.2004.12.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Accepted: 09/01/2004] [Indexed: 10/25/2022]
Abstract
Lipid rafts are defined as detergent-resistant membrane microdomains of specific lipid and protein composition. They are involved in many aspects of cell biology, including T-cell activation and immunoreceptor signaling. This review discusses current controversies around lipid rafts and summarizes recent developments in the area.
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Affiliation(s)
- Václav Horejsí
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic.
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Laulagnier K, Grand D, Dujardin A, Hamdi S, Vincent-Schneider H, Lankar D, Salles JP, Bonnerot C, Perret B, Record M. PLD2 is enriched on exosomes and its activity is correlated to the release of exosomes. FEBS Lett 2004; 572:11-4. [PMID: 15304316 DOI: 10.1016/j.febslet.2004.06.082] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2004] [Accepted: 06/28/2004] [Indexed: 11/23/2022]
Abstract
Exosomes are small vesicles secreted by different immune cells and which display anti-tumoral properties. Stimulation of RBL-2H3 cells with ionomycin triggered phospholipase D2 (PLD2) translocation from plasma membrane to intracellular compartments and the release of exosomes. Although exosomes carry the two isoforms of PLD, PLD2 was enriched and specifically sorted on exosomes when overexpressed in cells. PLD activity present on exosomes was clearly increased following PLD2 overexpression. PLD2 activity in cells was correlated to the amount of exosome released, as measured by FACS. Therefore, the present work indicates that exosomes can vehicle signaling enzymes.
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Affiliation(s)
- Karine Laulagnier
- Département Lipoprotéines et Médiateurs Lipidiques, INSERM U563, CPTP, Bât C, CHU Purpan, Place Baylac, BP3028, 31024 Toulouse Cedex 3, France
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Hitomi T, Zhang J, Nicoletti LM, Grodzki ACG, Jamur MC, Oliver C, Siraganian RP. Phospholipase D1 regulates high-affinity IgE receptor-induced mast cell degranulation. Blood 2004; 104:4122-8. [PMID: 15339843 DOI: 10.1182/blood-2004-06-2091] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To investigate the role of phospholipase D (PLD) in FcepsilonRI signaling, the wild-type or the catalytically inactive forms of PLD1 or PLD2 were stably overexpressed in RBL-2H3 mast cells. FcepsilonRI stimulation resulted in the activation of both PLD1 and PLD2. However, PLD1 was the source of most of the receptor-induced PLD activity. There was enhanced FcepsilonRI-induced degranulation only in cells that overexpressed the catalytically inactive PLD1. This dominant-negative PLD1 enhanced FcepsilonRI-induced tyrosine phosphorylations of early signaling molecules such as the receptor subunits, Syk and phospholipase C-gamma which resulted in faster release of Ca(2+) from intracellular sources. Therefore, PLD1 negatively regulates signals upstream of the Ca(2+) response. However, FcepsilonRI-induced PLD activation required Syk and was downstream of the Ca(2+)response, suggesting that basal PLD1 activity rather than that activated by cell stimulation controlled these early signaling events. Dominant-negative PLD1 reduced the basal phosphatidic acid formation in unstimulated cells, which was accompanied by an increase in FcepsilonRI within the lipid rafts. These results indicate that constitutive basal PLD1 activity by regulating phosphatidic acid formation controls the early signals initiated by FcepsilonRI aggregation that lead to mast cell degranulation.
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Affiliation(s)
- Tomohiro Hitomi
- Receptors and Signal Transduction Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA.
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