1
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Structured clustering of the glycosphingolipid GM1 is required for membrane curvature induced by cholera toxin. Proc Natl Acad Sci U S A 2020; 117:14978-14986. [PMID: 32554490 DOI: 10.1073/pnas.2001119117] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
AB5 bacterial toxins and polyomaviruses induce membrane curvature as a mechanism to facilitate their entry into host cells. How membrane bending is accomplished is not yet fully understood but has been linked to the simultaneous binding of the pentameric B subunit to multiple copies of glycosphingolipid receptors. Here, we probe the toxin membrane binding and internalization mechanisms by using a combination of superresolution and polarized localization microscopy. We show that cholera toxin subunit B (CTxB) can induce membrane curvature only when bound to multiple copies of its glycosphingolipid receptor, GM1, and the ceramide structure of GM1 is likely not a determinant of this activity as assessed in model membranes. A mutant CTxB capable of binding only a single GM1 fails to generate curvature either in model membranes or in cells, and clustering the mutant CTxB-single-GM1 complexes by antibody cross-linking does not rescue the membrane curvature phenotype. We conclude that both the multiplicity and specific geometry of GM1 binding sites are necessary for the induction of membrane curvature. We expect this to be a general rule of membrane behavior for all AB5 toxins and polyomaviruses that bind glycosphingolipids to invade host cells.
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Enhanced Ordering in Monolayers Containing Glycosphingolipids: Impact of Carbohydrate Structure. Biophys J 2019. [PMID: 29539397 DOI: 10.1016/j.bpj.2017.12.044] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The influence of carbohydrate structure on the ordering of glycosphingolipids (GSLs) and surrounding phospholipids was investigated in monolayers at the air-water interface. Binary mixtures composed of GSLs, chosen to span a range of carbohydrate complexity, and zwitterionic dipalmitoylphosphatidylcholine phospholipid, were studied. X-ray reflectivity was used to measure the out-of-plane structure of the monolayers and characterize the extension and conformation of the GSL carbohydrates. Using synchrotron grazing incidence x-ray diffraction, the in-plane packing of the lipid acyl chains and the area per molecule within ordered domains were characterized at different mole ratios of the two components. Our findings indicate that GSL-containing mixtures, regardless of the carbohydrate size, enhance the ordering of the surrounding lipids, resulting in a larger fraction of ordered phase of the monolayer and greater dimensions of the ordered domains. Reduction of the averaged area per molecule within the ordered domains was also observed but only in the cases where there was a size mismatch between the phospholipid headgroups and GSL components, suggesting that the condensation mechanism involves the relief of steric interactions between headgroups in mixtures.
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3
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Hunter CD, Guo T, Daskhan G, Richards MR, Cairo CW. Synthetic Strategies for Modified Glycosphingolipids and Their Design as Probes. Chem Rev 2018; 118:8188-8241. [DOI: 10.1021/acs.chemrev.8b00070] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Carmanah D. Hunter
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Tianlin Guo
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Gour Daskhan
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Michele R. Richards
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Christopher W. Cairo
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
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4
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Huang FT, Han YB, Feng Y, Yang GY. A facile method for controlling the reaction equilibrium of sphingolipid ceramide N-deacylase for lyso-glycosphingolipid production. J Lipid Res 2015; 56:1836-42. [PMID: 26130766 DOI: 10.1194/jlr.d061176] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Indexed: 11/20/2022] Open
Abstract
Lyso-glycosphingolipids (lyso-GSLs), the N-deacylated forms of glycosphingolipids (GSLs), are important synthetic intermediates for the preparation of GSL analogs. Although lyso-GSLs can be produced by hydrolyzing natural GSLs using sphingolipid ceramide N-deacylase (SCDase), the yield for this reaction is usually low because SCDase also catalyzes the reverse reaction, ultimately establishing an equilibrium between hydrolysis and synthesis. In the present study, we developed an efficient method for controlling the reaction equilibrium by introducing divalent metal cation and detergent in the enzymatic reaction system. In the presence of both Ca(2+) and taurodeoxycholate hydrate, the generated fatty acids were precipitated by the formation of insoluble stearate salts and pushing the reaction equilibrium toward hydrolysis. The yield of GM1 hydrolysis can be achieved as high as 96%, with an improvement up to 45% compared with the nonoptimized condition. In preparative scale, 75 mg of lyso-GM1 was obtained from 100 mg of GM1 with a 90% yield, which is the highest reported yield to date. The method can also be used for the efficient hydrolysis of a variety of GSLs and sphingomyelin. Thus, this method should serve as a facile, easily scalable, and general tool for lyso-GSL production to facilitate further GSL research.
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Affiliation(s)
- Feng-Tao Huang
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yun-Bin Han
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yan Feng
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Guang-Yu Yang
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China Shanghai Collaborative Innovation Center for Biomanufacturing (SCICB), East China University of Science and Technology, Shanghai 200237, China
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5
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Number of sialic acid residues in ganglioside headgroup affects interactions with neighboring lipids. Biophys J 2014; 105:1421-31. [PMID: 24047994 DOI: 10.1016/j.bpj.2013.07.051] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 07/01/2013] [Accepted: 07/19/2013] [Indexed: 11/21/2022] Open
Abstract
Monolayers of binary mixtures of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and asialo-(GA1), disialo-(GD1b) and trisialo-(GT1b) gangliosides were used to determine the effect of ganglioside headgroup charge and geometry on its interactions with the neighboring zwitterionic lipid. Surface pressure versus molecular area isotherm measurements along with concurrent fluorescence microscopy of the monolayers at the air-water interface were complemented with atomic force microscopy imaging of monolayers deposited on solid substrates. Results were used to further develop a proposed geometric packing model that the complementary geometry of DPPC and monosialoganglioside GM1 headgroups affects their close molecular packing, inducing condensation of the layer at small mol % of ganglioside. For GA1, GD1b, and GT1b, a similar condensing effect, followed by a fluidizing effect is seen that varies with glycosphingolipid concentration, but results do not directly follow from geometric arguments because less DPPC is needed to condense ganglioside molecules with larger cross-sectional areas. The variations in critical packing mole ratios can be explained by global effects of headgroup charge and resultant dipole moments within the monolayer. Atomic force microscopy micrographs further support the model of ganglioside-induced DPPC condensation with condensed domains composed of a striped phase of condensed DPPC and DPPC/ganglioside geometrically packed complexes at low concentrations.
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Chinnapen DJF, Hsieh WT, te Welscher YM, Saslowsky DE, Kaoutzani L, Brandsma E, D'Auria L, Park H, Wagner JS, Drake KR, Kang M, Benjamin T, Ullman MD, Costello CE, Kenworthy AK, Baumgart T, Massol RH, Lencer WI. Lipid sorting by ceramide structure from plasma membrane to ER for the cholera toxin receptor ganglioside GM1. Dev Cell 2013; 23:573-86. [PMID: 22975326 DOI: 10.1016/j.devcel.2012.08.002] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 04/06/2012] [Accepted: 08/04/2012] [Indexed: 01/26/2023]
Abstract
The glycosphingolipid GM1 binds cholera toxin (CT) on host cells and carries it retrograde from the plasma membrane (PM) through endosomes, the trans-Golgi (TGN), and the endoplasmic reticulum (ER) to induce toxicity. To elucidate how a membrane lipid can specify trafficking in these pathways, we synthesized GM1 isoforms with alternate ceramide domains and imaged their trafficking in live cells. Only GM1 with unsaturated acyl chains sorted efficiently from PM to TGN and ER. Toxin binding, which effectively crosslinks GM1 lipids, was dispensable, but membrane cholesterol and the lipid raft-associated proteins actin and flotillin were required. The results implicate a protein-dependent mechanism of lipid sorting by ceramide structure and provide a molecular explanation for the diversity and specificity of retrograde trafficking by CT in host cells.
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Affiliation(s)
- Daniel J-F Chinnapen
- Division of Gastroenterology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
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7
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Jobling MG, Yang Z, Kam WR, Lencer WI, Holmes RK. A single native ganglioside GM1-binding site is sufficient for cholera toxin to bind to cells and complete the intoxication pathway. mBio 2012; 3:e00401-12. [PMID: 23111873 PMCID: PMC3487775 DOI: 10.1128/mbio.00401-12] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 10/05/2012] [Indexed: 01/02/2023] Open
Abstract
Cholera toxin (CT) from Vibrio cholerae is responsible for the majority of the symptoms of the diarrheal disease cholera. CT is a heterohexameric protein complex with a 240-residue A subunit and a pentameric B subunit of identical 103-residue B polypeptides. The A subunit is proteolytically cleaved within a disulfide-linked loop to generate the A1 and A2 fragments. The B subunit of wild-type (wt) CT binds 5 cell surface ganglioside GM(1) (GM(1)) molecules, and the toxin-GM(1) complex traffics from the plasma membrane (PM) retrograde through endosomes and the Golgi apparatus to the endoplasmic reticulum (ER). From the ER, the enzymatic A1 fragment retrotranslocates to the cytosol to cause disease. Clustering of GM(1) by multivalent toxin binding can structurally remodel cell membranes in ways that may assist toxin uptake and retrograde trafficking. We have recently found, however, that CT may traffic from the PM to the ER by exploiting an endogenous glycosphingolipid pathway (A. A. Wolf et al., Infect. Immun. 76:1476-1484, 2008, and D. J. F. Chinnapen et al., Dev. Cell 23:573-586, 2012), suggesting that multivalent binding to GM(1) is dispensable. Here we formally tested this idea by creating homogenous chimeric holotoxins with defined numbers of native GM(1) binding sites from zero (nonbinding) to five (wild type). We found that a single GM(1) binding site is sufficient for activity of the holotoxin. Therefore, remodeling of cell membranes by mechanisms that involve multivalent binding of toxin to GM(1) receptors is not essential for toxicity of CT. Through multivalent binding to its lipid receptor, cholera toxin (CT) can remodel cell membranes in ways that may assist host cell invasion. We recently found that CT variants which bind no more than 2 receptor molecules do exhibit toxicity, suggesting that CT may be able to enter cells by coopting an endogenous lipid sorting pathway without clustering receptors. We tested this idea directly by using purified variants of CT with zero to five functional receptor-binding sites (BS). One BS enabled CT to intoxicate cells, supporting the conclusion that CT can enter cells by coopting an endogenous lipid-sorting pathway. Although multivalent receptor binding is not essential, it does increase CT toxicity. These findings suggest that achieving higher receptor binding avidity or affecting membrane dynamics by lipid clustering and membrane remodeling may be driving forces for evolution of AB(5) subunit toxins that can bind multivalently to cell membrane lipid receptors.
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Affiliation(s)
- Michael G. Jobling
- Department of Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - ZhiJie Yang
- Department of Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Wendy R. Kam
- GI Cell Biology, Department of Pediatrics, Children’s Hospital, Boston, Massachusetts, USA; and
| | | | - Randall K. Holmes
- Department of Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
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8
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Mrówczyńska L, Lindqvist C, Iglič A, Hägerstrand H. Spontaneous curvature of ganglioside GM1--effect of cross-linking. Biochem Biophys Res Commun 2012; 422:776-9. [PMID: 22634013 DOI: 10.1016/j.bbrc.2012.05.083] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 05/16/2012] [Indexed: 11/28/2022]
Abstract
The membrane-curvature dependent lateral distribution of outer leaflet ganglioside GM1 (GM1) and the influence of GM1 cross-linking induced by fluorophore-tagged cholera toxin subunit B (CTB) plus anti-CTB was analysed in cell membranes by fluorescence microscopy. Data are presented indicating that cross-linked GM1-ligand patches accumulated at the tips of human erythrocyte echinocytic spiculae induced by Ca(2+)/ionophore A23187. However, when lipid fixative osmium tetroxide was added prior to the ligand no accumulation in spiculae occurred. GM1-staining remained here distributed over the spheroid cell body and in spiculae. Similarly, osmium tetroxide completely prohibited CTB plus anti-CTB-induced GM1 patching in representatives for flat membrane, i.e. discoid erythrocytes and K562 cells. Our results demonstrate that GM1 per se shows low membrane curvature dependent distribution and therefore holds flexible spontaneous curvature. In contrast, the cross-linked GM1-ligand complex has a strong preference for highly outward curved membrane and possesses overall positive spontaneous curvature. Osmium tetroxide efficiently immobilises GM1.
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Affiliation(s)
- Lucyna Mrówczyńska
- Department of Cell Biology, A. Mickiewicz University, Umultowska 89, PL-61614 Poznań, Poland.
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9
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Curvature factor and membrane solubilization, with particular reference to membrane rafts. Cell Biol Int 2012; 35:991-5. [PMID: 21438858 DOI: 10.1042/cbi20100786] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The composition of membrane rafts (cholesterol/sphingolipid-rich domains) cannot be fully deduced from the analysis of a detergent-resistant membrane fraction after solubilization in Triton X-100 at 4°C. It is hypothesized that the membrane curvature-dependent lateral distribution of membrane components affects their solubilization. The stomatocytogenic, Triton X-100, cannot effectively solubilize membrane components, especially with regard to the outward membrane curvature.
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10
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Abstract
The combination of carbohydrate and lipid generates unusual molecules in which the two distinctive halves of the glycoconjugate influence the function of each other. Membrane glycolipids can act as primary receptors for carbohydrate binding proteins to mediate transmembrane signaling despite restriction to the outer bilayer leaflet. The extensive heterogeneity of the lipid moiety plays a significant, but still largely unknown, role in glycosphingolipid function. Potential interplay between glycolipids and their fatty acid isoforms, together with their preferential interaction with cholesterol, generates a complex mechanism for the regulation of their function in cellular physiology.
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Affiliation(s)
- Clifford A Lingwood
- Research Institute, Hospital for Sick Children, Molecular Structure and Function, Toronto, Ontario M5G 1X8, Canada.
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11
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Tanaka K, Yamada M, Tamiya-Koizumi K, Kannagi R, Aoyama T, Hara A, Kyogashima M. Systematic analyses of free ceramide species and ceramide species comprising neutral glycosphingolipids by MALDI-TOF MS with high-energy CID. Glycoconj J 2011; 28:67-87. [DOI: 10.1007/s10719-011-9325-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 01/11/2011] [Accepted: 02/01/2011] [Indexed: 10/18/2022]
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12
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Wernick NLB, Chinnapen DJF, Cho JA, Lencer WI. Cholera toxin: an intracellular journey into the cytosol by way of the endoplasmic reticulum. Toxins (Basel) 2010; 2:310-25. [PMID: 22069586 PMCID: PMC3153193 DOI: 10.3390/toxins2030310] [Citation(s) in RCA: 146] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Revised: 02/27/2010] [Accepted: 03/02/2010] [Indexed: 01/09/2023] Open
Abstract
Cholera toxin (CT), an AB(5)-subunit toxin, enters host cells by binding the ganglioside GM1 at the plasma membrane (PM) and travels retrograde through the trans-Golgi Network into the endoplasmic reticulum (ER). In the ER, a portion of CT, the enzymatic A1-chain, is unfolded by protein disulfide isomerase and retro-translocated to the cytosol by hijacking components of the ER associated degradation pathway for misfolded proteins. After crossing the ER membrane, the A1-chain refolds in the cytosol and escapes rapid degradation by the proteasome to induce disease by ADP-ribosylating the large G-protein Gs and activating adenylyl cyclase. Here, we review the mechanisms of toxin trafficking by GM1 and retro-translocation of the A1-chain to the cytosol.
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Affiliation(s)
- Naomi L. B. Wernick
- GI Cell Biology, Children's Hospital (and Harvard Medical School), 300 Longwood Avenues, Enders 720, Boston, MA 02115, USA; (N.L.B.W.); (D.J.-F.C.); (J.A.C.)
| | - Daniel J.-F. Chinnapen
- GI Cell Biology, Children's Hospital (and Harvard Medical School), 300 Longwood Avenues, Enders 720, Boston, MA 02115, USA; (N.L.B.W.); (D.J.-F.C.); (J.A.C.)
| | - Jin Ah Cho
- GI Cell Biology, Children's Hospital (and Harvard Medical School), 300 Longwood Avenues, Enders 720, Boston, MA 02115, USA; (N.L.B.W.); (D.J.-F.C.); (J.A.C.)
| | - Wayne I. Lencer
- GI Cell Biology, Children's Hospital (and Harvard Medical School), 300 Longwood Avenues, Enders 720, Boston, MA 02115, USA; (N.L.B.W.); (D.J.-F.C.); (J.A.C.)
- The Harvard Digestive Diseases Center, Boston, MA 02115, USA
- Author to whom correspondence should be addressed; ; Tel.: +617-919-2573; Fax: +617-730-0498
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13
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Lingwood CA, Manis A, Mahfoud R, Khan F, Binnington B, Mylvaganam M. New aspects of the regulation of glycosphingolipid receptor function. Chem Phys Lipids 2010; 163:27-35. [DOI: 10.1016/j.chemphyslip.2009.09.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 09/15/2009] [Accepted: 09/16/2009] [Indexed: 12/19/2022]
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14
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Triton X-100 promotes a cholesterol-dependent condensation of the plasma membrane. Biochem J 2009; 420:373-81. [DOI: 10.1042/bj20090051] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The molecular components of membrane rafts are frequently defined by their biochemical partitioning into detergent-resistant membranes. In the present study, we used a combination of epifluorescence and two-photon microscopy to visualize and quantify whether this insolubility in detergent reflects a pre-existing organization of the PM (plasma membrane). We found that the treatment of cells with cold TX (Triton X-100) promotes a profound remodelling of the PM, including a rapid rearrangement of the glycosphingolipid GM1 and cholesterol into newly formed structures, only partial solubilization of fluid domains and the formation of condensed domains that cover 51% of the remaining membrane. TX does not appear to induce the coalescence of pre-existing domains; instead, the domains that remain after TX treatment seem to be newly formed with a higher degree of condensation than those observed in native membranes. However, when cholesterol was complexed physically by treatment with a second detergent, such as saponin, cholesterol did not separate into the newly formed structures, condensation of the domains was unaltered, and the relative area corresponding to ordered domains increased to occupy 62% of the remaining membrane. Our results suggest that detergent can be used to enrich ordered domains for biochemical analysis, but that TX treatment alone substantially alters the lateral organization of the PM.
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15
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Preparation of Alexa Fluor 350-conjugated nonradioactive or 3H-labeled GM1 ganglioside derivatives with different ceramides. Anal Biochem 2009; 385:168-70. [DOI: 10.1016/j.ab.2008.10.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 10/04/2008] [Accepted: 10/07/2008] [Indexed: 11/22/2022]
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16
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The ceramide structure of GM1 ganglioside differently affects its recovery in low-density membrane fractions prepared from HL-60 cells with or without triton-X100. Cell Mol Biol Lett 2008; 14:175-89. [PMID: 18979068 PMCID: PMC6275918 DOI: 10.2478/s11658-008-0043-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Accepted: 07/11/2008] [Indexed: 12/24/2022] Open
Abstract
Gangliosides are characteristically enriched in various membrane domains that can be isolated as low density membrane fraction insoluble in detergents (detergent-resistant membranes, DRMs) or obtained after homogenization and sonication in 0.5 M sodium carbonate (low-density membranes, LDMs). We assessed the effect of the ceramide structure of four [3H]-labeled GM1 ganglioside molecular species (GM1s) taken up by HL-60 cells on their occurrence in LDMs, and compared it with our previous observations for DRMs. All GM1s contained C18 sphingosine, which was acetylated in GM1(18:1/2) or acylated with C14, C18 or C18:1 fatty acids (Fas)
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17
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Attenuated endocytosis and toxicity of a mutant cholera toxin with decreased ability to cluster ganglioside GM1 molecules. Infect Immun 2008; 76:1476-84. [PMID: 18212085 DOI: 10.1128/iai.01286-07] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cholera toxin (CT) moves from the plasma membrane (PM) of host cells to the endoplasmic reticulum (ER) by binding to the lipid raft ganglioside GM(1). The homopentomeric B-subunit of the toxin can bind up to five GM(1) molecules at once. Here, we examined the role of polyvalent binding of GM(1) in CT action by producing chimeric CTs that had B-subunits with only one or two normal binding pockets for GM(1). The chimeric toxins had attenuated affinity for binding to host cell PM, as expected. Nevertheless, like wild-type (wt) CT, the CT chimeras induced toxicity, fractionated with detergent-resistant membranes extracted from toxin-treated cells, displayed restricted diffusion in the plane of the PM in intact cells, and remained bound to GM(1) when they were immunoprecipitated. Thus, binding normally to two or perhaps only one GM(1) molecule is sufficient for association with lipid rafts in the PM and toxin action. The chimeric toxins, however, were much less potent than wt toxin, and they entered the cell by endocytosis more slowly, suggesting that clustering of GM(1) molecules by the B-subunit enhances the efficiency of toxin uptake and perhaps also trafficking to the ER.
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18
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Tanphaichitr N, Faull KF, Yaghoubian A, Xu H. Lipid Rafts and Sulfogalactosylglycerolipid (SGG) in Sperm Functions: Consensus and Controversy. TRENDS GLYCOSCI GLYC 2007. [DOI: 10.4052/tigg.19.67] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Sillence DJ. New insights into glycosphingolipid functions--storage, lipid rafts, and translocators. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 262:151-89. [PMID: 17631188 DOI: 10.1016/s0074-7696(07)62003-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Glycosphingolipids are key components of eukaryotic cellular membranes. Through their propensity to form lipid rafts, they are important in membrane transport and signaling. At the cell surface, they are required for caveolar-mediated endocytosis, a process required for the action of many glycosphingolipid-binding toxins. Glycosphingolipids also exist intracellularly, on both leaflets of organelle membranes. It is expected that dissecting the mechanisms of cell pathology seen in the glycosphingolipid storage diseases, where lysosomal glycosphingolipid degradation is defective, will reveal their functions. Disrupted cation gradients in Mucolipidosis type IV disease are interlinked with glycosphingolipid storage, defective rab 7 function, and the activation of autophagy. Relationships between drug translocators and glycosphingolipid synthesis are also discussed. Mass spectrometry of cell lines defective in drug transporters reveal clear differences in glycosphingolipid mass and fatty acid composition. The potential roles of glycosphingolipids in lipid raft formation, endocytosis, and cationic gradients are discussed.
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Affiliation(s)
- Dan J Sillence
- Leicester School of Pharmacy, Hawthorne Building, De Montfort University, Leicester, LE1 9BH, United Kingdom
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20
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Bou Khalil M, Chakrabandhu K, Xu H, Weerachatyanukul W, Buhr M, Berger T, Carmona E, Vuong N, Kumarathasan P, Wong PTT, Carrier D, Tanphaichitr N. Sperm capacitation induces an increase in lipid rafts having zona pellucida binding ability and containing sulfogalactosylglycerolipid. Dev Biol 2006; 290:220-35. [PMID: 16387295 DOI: 10.1016/j.ydbio.2005.11.030] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2005] [Revised: 11/10/2005] [Accepted: 11/15/2005] [Indexed: 01/13/2023]
Abstract
Sperm gain full ability to bind to the zona(e) pellucida(e) (ZP) during capacitation. Since lipid rafts are implicated in cell adhesion, we determined whether capacitated sperm lipid rafts had affinity for the ZP. We demonstrated that lipid rafts, isolated as low-density detergent resistant membranes (DRMs), from capacitated pig sperm had ability to bind to homologous ZP. This binding was dependent on pig ZPB glycoprotein, a major participant in sperm binding. Capacitated sperm DRMs were also enriched in the male germ cell specific sulfogalactosylglycerolipid (SGG), which contributed to DRMs-ZP binding. Furthermore, SGG may participate in the formation of sperm DRMs due to its interaction with cholesterol, an integral component of lipid rafts, as shown by infrared spectroscopic studies. Since sperm capacitation is associated with cholesterol efflux from the sperm membrane, we questioned whether the formation of DRMs was compromised in capacitated sperm. Our studies indeed revealed that capacitation induced increased levels of sperm DRMs, with an enhanced ZP affinity. These results corroborated the implication of lipid rafts and SGG in cell adhesion and strongly suggested that the enhanced ZP binding ability of capacitated sperm may be attributed to increased levels and a greater ZP affinity of lipid rafts in the sperm plasma membrane.
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Affiliation(s)
- Maroun Bou Khalil
- Hormones/Growth/Development Group, Ottawa Health Research Institute, Ottawa, ON, Canada K1Y 4E9
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Rouquette-Jazdanian AK, Foussat A, Lamy L, Pelassy C, Lagadec P, Breittmayer JP, Aussel C. Cholera toxin B-subunit prevents activation and proliferation of human CD4+ T cells by activation of a neutral sphingomyelinase in lipid rafts. THE JOURNAL OF IMMUNOLOGY 2005; 175:5637-48. [PMID: 16237053 DOI: 10.4049/jimmunol.175.9.5637] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The inhibition of human CD4+ T lymphocyte activation and proliferation by cholera toxin B-subunit (CTB) is a well-established phenomenon; nevertheless, the exact mechanism remained unclear. In the present study, we propose an explanation for the rCTB-induced inhibition of CD4+ T lymphocytes. rCTB specifically binds to GM1, a raft marker, and strongly modifies the lipid composition of rafts. First, rCTB inhibits sphingomyelin synthesis; second, it enhances phosphatidylcholine synthesis; and third, it activates a raft-resident neutral sphingomyelinase resembling to neutral sphingomyelinase type 1, thus generating a transient ceramide production. We demonstrated that these ceramides inhibit protein kinase Calpha phosphorylation and its translocation into the modified lipid rafts. Furthermore, we show that rCTB-induced ceramide production activate NF-kappaB. Combined all together: raft modification in terms of lipids, ceramide production, protein kinase Calpha inhibition, and NF-kappaB activation lead to CD4+ T cell inhibition.
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Affiliation(s)
- Alexandre K Rouquette-Jazdanian
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unit 576, IFR 50, Hôpital de l'Archet I, Nice Cedex 3, France
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Panasiewicz M, Mieczkowski J, Domek H, Pacuszka T. HPLC-based procedure for the preparation of carbene-generating photoreactive GM3 and GM1 ganglioside derivatives radioiodinated to high specific radioactivity with chloramine T as an oxidant. Anal Biochem 2005; 340:373-5. [PMID: 15840512 DOI: 10.1016/j.ab.2004.11.044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2004] [Indexed: 11/27/2022]
Affiliation(s)
- Mirosława Panasiewicz
- Department of Biochemistry, Medical Center of Postgraduate Education, 01-813 Warszawa, Poland
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Pike LJ. Lipid rafts: heterogeneity on the high seas. Biochem J 2004; 378:281-92. [PMID: 14662007 PMCID: PMC1223991 DOI: 10.1042/bj20031672] [Citation(s) in RCA: 544] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2003] [Revised: 12/05/2003] [Accepted: 12/08/2003] [Indexed: 11/17/2022]
Abstract
Lipid rafts are membrane microdomains that are enriched in cholesterol and glycosphingolipids. They have been implicated in processes as diverse as signal transduction, endocytosis and cholesterol trafficking. Recent evidence suggests that this diversity of function is accompanied by a diversity in the composition of lipid rafts. The rafts in cells appear to be heterogeneous both in terms of their protein and their lipid content, and can be localized to different regions of the cell. This review summarizes the data supporting the concept of heterogeneity among lipid rafts and outlines the evidence for cross-talk between raft components. Based on differences in the ways in which proteins interact with rafts, the Induced-Fit Model of Raft Heterogeneity is proposed to explain the establishment and maintenance of heterogeneity within raft populations.
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Affiliation(s)
- Linda J Pike
- Washington University School of Medicine, Department of Biochemistry and Molecular Biophysics, 660 So. Euclid Avenue, Box 8231, St. Louis, MO 63110, USA.
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