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Rosenhouse-Dantsker A, Gazgalis D, Logothetis DE. PI(4,5)P 2 and Cholesterol: Synthesis, Regulation, and Functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:3-59. [PMID: 36988876 DOI: 10.1007/978-3-031-21547-6_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is the most abundant membrane phosphoinositide and cholesterol is an essential component of the plasma membrane (PM). Both lipids play key roles in a variety of cellular functions including as signaling molecules and major regulators of protein function. This chapter provides an overview of these two important lipids. Starting from a brief description of their structure, synthesis, and regulation, the chapter continues to describe the primary functions and signaling processes in which PI(4,5)P2 and cholesterol are involved. While PI(4,5)P2 and cholesterol can act independently, they often act in concert or affect each other's impact. The chapters in this volume on "Cholesterol and PI(4,5)P2 in Vital Biological Functions: From Coexistence to Crosstalk" focus on the emerging relationship between cholesterol and PI(4,5)P2 in a variety of biological systems and processes. In this chapter, the next section provides examples from the ion channel field demonstrating that PI(4,5)P2 and cholesterol can act via common mechanisms. The chapter ends with a discussion of future directions.
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Affiliation(s)
| | - Dimitris Gazgalis
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
| | - Diomedes E Logothetis
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
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2
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Morris RJ. Thy-1, a Pathfinder Protein for the Post-genomic Era. Front Cell Dev Biol 2018; 6:173. [PMID: 30619853 PMCID: PMC6305390 DOI: 10.3389/fcell.2018.00173] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 12/06/2018] [Indexed: 12/21/2022] Open
Abstract
Thy-1 is possibly the smallest of cell surface proteins – 110 amino acids folded into an Immunoglobulin variable domain, tethered to the outer leaflet of the cell surface membrane via just the two saturated fatty acids of its glycosylphosphatidylinositol (GPI) anchor. Yet Thy-1 is emerging as a key regulator of differentiation in cells of endodermal, mesodermal, and ectodermal origin, acting as both a ligand (for certain integrins and other receptors), and as a receptor, able to modulate signaling and hence differentiation in the Thy-1-expressing cell. This is an extraordinary diversity of molecular pathways to be controlled by a molecule that does not even cross the cell membrane. Here I review aspects of the cell biology of Thy-1, and studies of its role as deduced from gene knock-out studies, that suggest how this protein can participate in so many different signaling-related functions. While mechanisms differ in molecular detail, it appears overall that Thy-1 dampens down signaling to control function.
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Affiliation(s)
- Roger J Morris
- Department of Chemistry, King's College London, London, United Kingdom
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3
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Xue F, Lennon AB, McKayed KK, Campbell VA, Prendergast PJ. Effect of membrane stiffness and cytoskeletal element density on mechanical stimuli within cells: an analysis of the consequences of ageing in cells. Comput Methods Biomech Biomed Engin 2013; 18:468-76. [PMID: 23947334 DOI: 10.1080/10255842.2013.811234] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
A finite element model of a single cell was created and used to compute the biophysical stimuli generated within a cell under mechanical loading. Major cellular components were incorporated in the model: the membrane, cytoplasm, nucleus, microtubules, actin filaments, intermediate filaments, nuclear lamina and chromatin. The model used multiple sets of tensegrity structures. Viscoelastic properties were assigned to the continuum components. To corroborate the model, a simulation of atomic force microscopy indentation was performed and results showed a force/indentation simulation with the range of experimental results. A parametric analysis of both increasing membrane stiffness (thereby modelling membrane peroxidation with age) and decreasing density of cytoskeletal elements (thereby modelling reduced actin density with age) was performed. Comparing normal and aged cells under indentation predicts that aged cells have a lower membrane area subjected to high strain as compared with young cells, but the difference, surprisingly, is very small and may not be measurable experimentally. Ageing is predicted to have a more significant effect on strain deep in the nucleus. These results show that computation of biophysical stimuli within cells are achievable with single-cell computational models; correspondence between computed and measured force/displacement behaviours provides a high-level validation of the model. Regarding the effect of ageing, the models suggest only small, although possibly physiologically significant, differences in internal biophysical stimuli between normal and aged cells.
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Affiliation(s)
- Feng Xue
- a Trinity Centre for Bioengineering, School of Engineering, Trinity College Dublin , Dublin , Ireland
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4
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Kendall EL, Shao C, DeVoe DL. Visualizing the growth and dynamics of liquid-ordered domains during lipid bilayer folding in a microfluidic chip. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:3613-3619. [PMID: 22888063 DOI: 10.1002/smll.201200831] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 05/29/2012] [Indexed: 06/01/2023]
Abstract
A microfluidic platform enabling optical monitoring of bilayer lipid membrane formation by a new monolayer folding process is described. The thermoplastic chips integrate dried lipid films that are rehydrated by microfluidic perfusion, which enables delivery of lipid-laden air bubbles across a membrane-supporting aperture. As in traditional Montal-Mueller bilayer formation, lipid monolayers are delivered independently to each side of the aperture, thereby allowing asymmetric lipid composition in the resulting bilayer to be achieved. Confocal microscopy is used to image the monolayer folding process, and reveals the growth and dynamics of asymmetric liquid-ordered domains during bilayer stabilization.
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Affiliation(s)
- Eric L Kendall
- Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA
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5
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Cacas JL, Furt F, Le Guédard M, Schmitter JM, Buré C, Gerbeau-Pissot P, Moreau P, Bessoule JJ, Simon-Plas F, Mongrand S. Lipids of plant membrane rafts. Prog Lipid Res 2012; 51:272-99. [PMID: 22554527 DOI: 10.1016/j.plipres.2012.04.001] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lipids tend to organize in mono or bilayer phases in a hydrophilic environment. While they have long been thought to be incapable of coherent lateral segregation, it is now clear that spontaneous assembly of these compounds can confer microdomain organization beyond spontaneous fluidity. Membrane raft microdomains have the ability to influence spatiotemporal organization of protein complexes, thereby allowing regulation of cellular processes. In this review, we aim at summarizing briefly: (i) the history of raft discovery in animals and plants, (ii) the main findings about structural and signalling plant lipids involved in raft segregation, (iii) imaging of plant membrane domains, and their biochemical purification through detergent-insoluble membranes, as well as the existing debate on the topic. We also discuss the potential involvement of rafts in the regulation of plant physiological processes, and further discuss the prospects of future research into plant membrane rafts.
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Affiliation(s)
- Jean-Luc Cacas
- Laboratoire de Biogenèse Membranaire, UMR 5200 CNRS, Université de Bordeaux, 146 Rue Léo Saignat, 33076 Bordeaux, France
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6
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Abstract
This article reviews the current knowledge and experimental research about the mechanisms by which fatty acids and their derivatives control specific gene expression involved during carcinogenesis. Changes in dietary fatty acids, specifically the polyunsaturated fatty acids of the ω-3 and ω-6 families and some derived eicosanoids from lipoxygenases, cyclooxygenases, and cytochrome P-450, seem to control the activity of transcription factor families involved in cancer cell proliferation or cell death. Their regulation may be carried out either through direct binding to DNA as peroxisome proliferator-activated receptors or via modulation in an indirect manner of signaling pathway molecules (e.g., protein kinase C) and other transcription factors (nuclear factor kappa B and sterol regulatory element binding protein). Knowledge of the mechanisms by which fatty acids control specific gene expression may identify important risk factors for cancer and provide insight into the development of new therapeutic strategies for a better management of whole body lipid metabolism.
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7
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Hoop CL, Sivanandam VN, Kodali R, Srnec MN, van der Wel PCA. Structural characterization of the caveolin scaffolding domain in association with cholesterol-rich membranes. Biochemistry 2012; 51:90-9. [PMID: 22142403 PMCID: PMC3290515 DOI: 10.1021/bi201356v] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 12/01/2011] [Indexed: 01/16/2023]
Abstract
Members of the caveolin protein family are implicated in the formation of caveolae and play important roles in a number of signaling pathways and in the regulation of various proteins. We employ complementary spectroscopic methods to study the structure of the caveolin scaffolding domain (CSD) in caveolin-1 fragments, while bound to cholesterol-rich membranes. This key domain is thought to be involved in multiple critical functions that include protein recognition, oligomerization, and cholesterol binding. In our membrane-bound peptides, residues within the flanking intramembrane domain (IMD) are found to adopt an α-helical structure, consistent with its commonly believed helical hairpin conformation. Intriguingly, in these same peptides, we observe a β-stranded conformation for residues in the CSD, contrasting with earlier reports, which commonly do not reflect β-structure. Our experimental data based on solid-state NMR, CD, and FTIR are found to be consistent with computational analyses of the secondary structure preference of the primary sequence. We discuss how our structural data of membrane binding Cav fragments may match certain general features of cholesterol-binding domains and could be consistent with the role for CSD in protein recognition and homo-oligomerization.
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Affiliation(s)
| | | | - Ravindra Kodali
- Department
of Structural Biology, University
of Pittsburgh School of Medicine, Biomedical Science
Tower 3, 3501 Fifth Ave., Pittsburgh, Pennsylvania 15260, United States
| | - Matthew N. Srnec
- Department
of Structural Biology, University
of Pittsburgh School of Medicine, Biomedical Science
Tower 3, 3501 Fifth Ave., Pittsburgh, Pennsylvania 15260, United States
| | - Patrick C. A. van der Wel
- Department
of Structural Biology, University
of Pittsburgh School of Medicine, Biomedical Science
Tower 3, 3501 Fifth Ave., Pittsburgh, Pennsylvania 15260, United States
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8
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Garner AE, Smith DA, Hooper NM. Sphingomyelin chain length influences the distribution of GPI-anchored proteins in rafts in supported lipid bilayers. Mol Membr Biol 2009; 24:233-42. [PMID: 17520480 DOI: 10.1080/09687860601127770] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Glycosyl-phosphatidylinositol (GPI)-anchored proteins are enriched in cholesterol- and sphingolipid-rich lipid rafts within the membrane. Rafts are known to have roles in cellular organization and function, but little is understood about the factors controlling the distribution of proteins in rafts. We have used atomic force microscopy to directly visualize proteins in supported lipid bilayers composed of equimolar sphingomyelin, dioleoyl-sn-glycero-3-phosphocholine and cholesterol. The transmembrane anchored angiotensin converting enzyme (TM-ACE) was excluded from the liquid ordered raft domains. Replacement of the transmembrane and cytoplasmic domains of TM-ACE with a GPI anchor (GPI-ACE) promoted the association of the protein with rafts in the bilayers formed with brain sphingomyelin (mainly C18:0). Association with the rafts did not occur if the shorter chain egg sphingomyelin (mainly C16:0) was used. The distribution of GPI-anchored proteins in supported lipid bilayers was investigated further using membrane dipeptidase (MDP) whose GPI anchor contains distearoyl phosphatidylinositol. MDP was also excluded from rafts when egg sphingomyelin was used but associated with raft domains formed using brain sphingomyelin. The effect of sphingomyelin chain length on the distribution of GPI-anchored proteins in rafts was verified using synthetic palmitoyl or stearoyl sphingomyelin. Both GPI-ACE and MDP only associated with the longer chain stearoyl sphingomyelin rafts. These data obtained using supported lipid bilayers provide the first direct evidence that the nature of the membrane-anchoring domain influences the association of a protein with lipid rafts and that acyl chain length hydrophobic mismatch influences the distribution of GPI-anchored proteins in rafts.
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Affiliation(s)
- Ashley E Garner
- Proteolysis Research Group, Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, and Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, UK
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9
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Zhang WX, Frahm G, Morley S, Manor D, Atkinson J. Effect of bilayer phospholipid composition and curvature on ligand transfer by the alpha-tocopherol transfer protein. Lipids 2009; 44:631-41. [PMID: 19458973 PMCID: PMC9784539 DOI: 10.1007/s11745-009-3310-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Accepted: 04/28/2009] [Indexed: 02/09/2023]
Abstract
We report here our preliminary investigations on the mechanism of alpha-TTP-mediated ligand transfer as assessed using fluorescence resonance energy transfer (FRET) assays. These assays monitor the movement of the model alpha-tocopherol fluorescent derivative ((R)-2,5,7,8-tetramethyl-chroman-2-[9-(7-nitro-benzo[1,2,5]oxadiazol-4-yl amino)-nonyl]-chroman-6-ol; NBD-Toc) from protein to acceptor vesicles containing the fluorescence quencher TRITC-PE. We have found that alpha-TTP utilizes a collisional mechanism of ligand transfer requiring direct protein-membrane contact, that rates of ligand transfer are greater to more highly curved lipid vesicles, and that such rates are insensitive to the presence of anionic phospholipids in the acceptor membrane. These results point to hydrophobic features of alpha-TTP dominating the binding energy between protein and membrane.
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Affiliation(s)
- Wen Xiao Zhang
- Department of Chemistry, Centre for Biotechnology, Brock University, 500 Glenridge Ave, St. Catharines, ON L2S 3A1, Canada
| | - Grant Frahm
- Department of Chemistry, Centre for Biotechnology, Brock University, 500 Glenridge Ave, St. Catharines, ON L2S 3A1, Canada
| | - Samantha Morley
- Department of Nutrition, School of Medicine, Case Western, Reserve University, Cleveland, OH 44106-4954, USA
| | - Danny Manor
- Department of Nutrition, School of Medicine, Case Western, Reserve University, Cleveland, OH 44106-4954, USA
| | - Jeffrey Atkinson
- Department of Chemistry, Centre for Biotechnology, Brock University, 500 Glenridge Ave, St. Catharines, ON L2S 3A1, Canada
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10
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Isolation at physiological temperature of detergent-resistant membranes with properties expected of lipid rafts: the influence of buffer composition. Biochem J 2008; 417:525-33. [DOI: 10.1042/bj20081385] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The failure of most non-ionic detergents to release patches of DRM (detergent-resistant membrane) at 37 °C undermines the claim that DRMs consist of lipid nanodomains that exist in an Lo (liquid ordered) phase on the living cell surface. In the present study, we have shown that inclusion of cations (Mg2+, K+) to mimic the intracellular environment stabilizes membranes during solubilization sufficiently to allow the isolation of DRMs at 37 °C, using either Triton X-100 or Brij 96. These DRMs are sensitive to chelation of cholesterol, maintain outside-out orientation of membrane glycoproteins, have prolonged (18 h) stability at 37 °C, and are vesicles or sheets up to 150–200 nm diameter. DRMs containing GPI (glycosylphosphatidylinositol)-anchored proteins PrP (prion protein) and Thy-1 can be separated by immunoaffinity isolation, in keeping with their separate organization and trafficking on the neuronal surface. Thy-1, but not PrP, DRMs are associated with actin. EM (electron microscopy) immunohistochemistry shows most PrP, and some Thy-1, to be clustered on DRMs, again maintaining their organization on the neuronal surface. For DRMs labelled for either protein, the bulk of the surface of the DRM is not labelled, indicating that the GPI-anchored protein is a minor component of its lipid domain. These 37 °C DRMs thus have properties expected of raft membrane, yet pose more questions about how proteins are organized within these nanodomains.
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11
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McIntosh AL, Atshaves BP, Huang H, Gallegos AM, Kier AB, Schroeder F. Fluorescence techniques using dehydroergosterol to study cholesterol trafficking. Lipids 2008; 43:1185-208. [PMID: 18536950 PMCID: PMC2606672 DOI: 10.1007/s11745-008-3194-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Accepted: 05/09/2008] [Indexed: 12/22/2022]
Abstract
Cholesterol itself has very few structural/chemical features suitable for real-time imaging in living cells. Thus, the advent of dehydroergosterol [ergosta-5,7,9(11),22-tetraen-3beta-ol, DHE] the fluorescent sterol most structurally and functionally similar to cholesterol to date, has proven to be a major asset for real-time probing/elucidating the sterol environment and intracellular sterol trafficking in living organisms. DHE is a naturally occurring, fluorescent sterol analog that faithfully mimics many of the properties of cholesterol. Because these properties are very sensitive to sterol structure and degradation, such studies require the use of extremely pure (>98%) quantities of fluorescent sterol. DHE is readily bound by cholesterol-binding proteins, is incorporated into lipoproteins (from the diet of animals or by exchange in vitro), and for real-time imaging studies is easily incorporated into cultured cells where it co-distributes with endogenous sterol. Incorporation from an ethanolic stock solution to cell culture media is effective, but this process forms an aqueous dispersion of DHE crystals which can result in endocytic cellular uptake and distribution into lysosomes which is problematic in imaging DHE at the plasma membrane of living cells. In contrast, monomeric DHE can be incorporated from unilamellar vesicles by exchange/fusion with the plasma membrane or from DHE-methyl-beta-cyclodextrin (DHE-MbetaCD) complexes by exchange with the plasma membrane. Both of the latter techniques can deliver large quantities of monomeric DHE with significant distribution into the plasma membrane. The properties and behavior of DHE in protein-binding, lipoproteins, model membranes, biological membranes, lipid rafts/caveolae, and real-time imaging in living cells indicate that this naturally occurring fluorescent sterol is a useful mimic for probing the properties of cholesterol in these systems.
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Affiliation(s)
- Avery L. McIntosh
- Department of Physiology and Pharmacology Texas A&M University, TVMC College Station, TX 77843-4466
| | - Barbara P. Atshaves
- Department of Physiology and Pharmacology Texas A&M University, TVMC College Station, TX 77843-4466
| | - Huan Huang
- Department of Physiology and Pharmacology Texas A&M University, TVMC College Station, TX 77843-4466
| | - Adalberto M. Gallegos
- Department of Pathobiology Texas A&M University, TVMC College Station, TX 77843-4467
| | - Ann B. Kier
- Department of Pathobiology Texas A&M University, TVMC College Station, TX 77843-4467
| | - Friedhelm Schroeder
- Department of Physiology and Pharmacology Texas A&M University, TVMC College Station, TX 77843-4466
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12
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Atkinson J, Epand RF, Epand RM. Tocopherols and tocotrienols in membranes: a critical review. Free Radic Biol Med 2008; 44:739-64. [PMID: 18160049 DOI: 10.1016/j.freeradbiomed.2007.11.010] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Revised: 11/09/2007] [Accepted: 11/12/2007] [Indexed: 12/14/2022]
Abstract
The familiar role of tocols (tocopherols and tocotrienols) as lipid-soluble chain-terminating inhibitors of lipid peroxidation is currently in the midst of a reinterpretation. New biological activities have been described for tocols that apparently are not dependent on their well-established antioxidant behaviour. These activities could well be real, but there remain large gaps in our understanding of the behaviour of tocols in membranes, especially when it comes to the alpha-, beta-, gamma-, delta-chroman methylation patterns and the seemingly special nature of tocotrienols. It is inappropriate to make conclusions and develop models based on in vivo (or cell culture) results with reference to in vitro measurements of antioxidant activity. When present in biological membranes, tocols will experience a large variation in the local composition of phospholipids and the presence of neutral lipids such as cholesterol, both of which would be expected to change the efficiency of antioxidant action. It is likely that tocols are not homogeneously dispersed in a membrane, but it is still not known whether any specific combination of lipid head group and acyl chains are conferred special protection from peroxidation, nor do we currently appreciate the structural role that tocols play in membranes. Tocols may enhance curvature stress or counteract similar stresses generated by other lipids such as lysolipids. This review will outline what is known about the location and behaviour of tocols in phospholipid bilayers. We will draw mainly from the biophysical literature, but will attempt to extend the discussion to biologically relevant phenomena when appropriate. We hope that it will assist researchers when designing new experiments and when critically assessing the results, in turn providing a more thorough understanding of the biochemistry of tocols.
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Affiliation(s)
- Jeffrey Atkinson
- Department of Chemistry and Centre for Biotechnology, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario, Canada.
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Patel HH, Murray F, Insel PA. G-protein-coupled receptor-signaling components in membrane raft and caveolae microdomains. Handb Exp Pharmacol 2008:167-84. [PMID: 18491052 DOI: 10.1007/978-3-540-72843-6_7] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The efficiency of signal transduction in cells derives in part from subcellular, in particular plasma membrane, microdomains that organize signaling molecules and signaling complexes. Two related plasma membrane domains that compartmentalize G-protein coupled receptor (GPCR) signaling complexes are lipid (membrane) rafts, domains that are enriched in certain lipids, including cholesterol and sphingolipids, and caveolae, a subset of lipid rafts that are enriched in the protein caveolin. This review focuses on the properties of lipid rafts and caveolae, the mechanisms by which they localize signaling molecules and the identity of GPCR signaling components that are organized in these domains.
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Affiliation(s)
- H H Patel
- Department of Anesthesiology, University of California, San Diego, La Jolla, CA 92093, USA
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Kusel JR, Al-Adhami BH, Doenhoff MJ. The schistosome in the mammalian host: understanding the mechanisms of adaptation. Parasitology 2007; 134:1477-526. [PMID: 17572930 DOI: 10.1017/s0031182007002971] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
SUMMARYIn this review, we envisage the host environment, not as a hostile one, since the schistosome thrives there, but as one in which the relationship between the two organisms consists of constant communication, through signalling mechanisms involving sense organs, surface glycocalyx, surface membrane and internal organs of the parasite, with host fluids and cells. The surface and secretions of the schistosome egg have very different properties from those of other parasite stages, but adapted for the dispersal of the eggs and for the preservation of host liver function. We draw from studies of mammalian cells and other organisms to indicate how further work might be carried out on the signalling function of the surface glycocalyx, the raft structure of the surface and existence of pores in the surface membrane, the repair of the surface membrane, the role of the membrane structure in ion channel function (including recent work on the actin cytoskeleton and calcium channels) and the possible role of P-glycoproteins in the adaptation of the parasite to its environment. We are speculative in some areas, such as the suggestions that variability in surface properties of schistosomes may relate to the existence of membrane rafts and that parasite communities may exhibit quorum sensing. This speculative approach is adopted with the hope that future work on the whole organisms and their interactions will be encouraged.
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Affiliation(s)
- J R Kusel
- Glasgow Biomedical Research Centre, University of Glasgow, Glasgow G12 8TA, UK.
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15
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Sobo K, Chevallier J, Parton RG, Gruenberg J, van der Goot FG. Diversity of raft-like domains in late endosomes. PLoS One 2007; 2:e391. [PMID: 17460758 PMCID: PMC1851096 DOI: 10.1371/journal.pone.0000391] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Accepted: 04/02/2007] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Late endosomes, the last sorting station in the endocytic pathway before lysosomes, are pleiomorphic organelles composed of tubular elements as well as vesicular regions with a characteristic multivesicular appearance, which play a crucial role in intracellular trafficking. Here, we have investigated whether, in addition to these morphologically distinguishable regions, late endosomal membranes are additionally sub-compartmentalized into membrane microdomains. METHODOLOGY/PRINCIPAL FINDINGS Using sub-organellar fractionation techniques, both with and without detergents, combined with electron microscopy, we found that both the limiting membrane of the organel and the intraluminal vesicles contain raft-type membrane domains. Interestingly, these differentially localized domains vary in protein composition and physico-chemical properties. CONCLUSIONS/SIGNIFICANCE In addition to the multivesicular organization, we find that late endosomes contain cholesterol rich microdomains both on their limiting membrane and their intraluminal vesicles that differ in composition and properties. Implications of these findings for late endosomal functions are discussed.
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Affiliation(s)
- Komla Sobo
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Julien Chevallier
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Robert G. Parton
- Institute for Molecular Bioscience, Centre for Microscopy and Microanalysis, and School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | - Jean Gruenberg
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - F. Gisou van der Goot
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
- Ecole Polytechnique Fédérale de Lausanne, SV-AI extension, Lausanne, Switzerland
- * To whom correspondence should be addressed. E-mail:
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16
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den Hertog AL, van Marle J, Veerman ECI, Valentijn-Benz M, Nazmi K, Kalay H, Grün CH, Van't Hof W, Bolscher JGM, Nieuw Amerongen AV. The human cathelicidin peptide LL-37 and truncated variants induce segregation of lipids and proteins in the plasma membrane of Candida albicans. Biol Chem 2006; 387:1495-502. [PMID: 17081124 DOI: 10.1515/bc.2006.187] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The human cathelicidin peptide LL-37 and several truncated variants differ in their capability to transmigrate over the plasma membrane of Candida albicans. We investigated whether retention at the cell perimeter or membrane transmigration affects their membrane-disrupting activities and candidacidal properties. Using fluorescein-labeled peptides, we demonstrate that LL-37 and its C-terminally truncated peptide LL-31 remain permanently associated with the perimeter of the cell. The N-terminally truncated peptide RK-31 initially accumulated at the cell boundary, but transmigrated into the cytoplasm within 30 min. The C-terminally truncated peptide LL-25 transmigrated instantaneously into the cytoplasm. The ultrastructural effects on the plasma membrane were studied by freeze-fracture electron microscopy combined with filipin cytochemistry. All peptides, whether they transmigrated over the plasma membrane or not, induced phase separation in the plasma membrane. All peptides induced leakage of cell components, including nucleotides and proteins. Proteins were identified by SDS-PAGE in combination with mass spectrometry, which revealed that predominantly proteins smaller than 50 kDa had leaked out of C. albicans.
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Affiliation(s)
- Alice L den Hertog
- Department of Oral Biochemistry, Academic Centre for Dentistry Amsterdam, Free University and University of Amsterdam, Van der Boechorststraat 7, NL-1081 BT Amsterdam, The Netherlands
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Cahuzac N, Baum W, Kirkin V, Conchonaud F, Wawrezinieck L, Marguet D, Janssen O, Zörnig M, Hueber AO. Fas ligand is localized to membrane rafts, where it displays increased cell death–inducing activity. Blood 2006; 107:2384-91. [PMID: 16282344 DOI: 10.1182/blood-2005-07-2883] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
AbstractFas ligand (FasL), a member of the TNF protein family, potently induces cell death by activating its matching receptor Fas. Fas-mediated killing plays a critical role in naturally and pathologically occurring cell death, including development and homeostasis of the immune system. In addition to its receptor-interacting and cell death–inducing extracellular domain, FasL has a well-conserved intracellular portion with a proline-rich SH3 domain–binding site probably involved in non-apoptotic functions. We report here that, as with the Fas receptor, a fraction of FasL is constitutively localized in rafts. These dynamic membrane microdomains, enriched in sphingolipids and cholesterol, are important for cell signaling and trafficking processes. We show that FasL is partially localized in rafts and that increased amounts of FasL are found in rafts after efficient FasL/Fas receptor interactions. Raft disorganization after cholesterol oxidase treatment and deletions within the intracellular FasL domain diminish raft partitioning and, most important, lead to decreased FasL killing. We conclude that FasL is recruited into lipid rafts for maximum Fas receptor contact and cell death–inducing potency. These findings raise the possibility that certain pathologic conditions may be treated by altering the cell death–inducing capability of FasL with drugs affecting its raft localization.
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Affiliation(s)
- Nathalie Cahuzac
- Institute of Signaling, Developmental Biology and Cancer Research, CNRS UMR 6543, 06189 Nice, France
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Lauc G, Heffer-Lauc M. Shedding and uptake of gangliosides and glycosylphosphatidylinositol-anchored proteins. Biochim Biophys Acta Gen Subj 2005; 1760:584-602. [PMID: 16388904 DOI: 10.1016/j.bbagen.2005.11.014] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 11/22/2005] [Accepted: 11/23/2005] [Indexed: 10/25/2022]
Abstract
Gangliosides and glycosylphosphatidylinositol (GPI)-anchored proteins have very different biosynthetic origin, but they have one thing in common: they are both comprised of a relatively large hydrophilic moiety tethered to a membrane by a relatively small lipid tail. Both gangliosides and GPI-anchored proteins can be actively shed from the membrane of one cell and taken up by other cells by insertion of their lipid anchors into the cell membrane. The process of shedding and uptake of gangliosides and GPI-anchored proteins has been independently discovered in several disciplines during the last few decades, but these discoveries were largely ignored by people working in other areas of science. By bringing together results from these, sometimes very distant disciplines, in this review, we give an overview of current knowledge about shedding and uptake of gangliosides and GPI-anchored proteins. Tumor cells and some pathogens apparently misuse this process for their own advantage, but its real physiological functions remain to be discovered.
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Affiliation(s)
- Gordan Lauc
- Department of Chemistry and Biochemistry, University of Osijek School of Medicine, Croatia.
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Compartmentation of G-protein-coupled receptors and their signalling components in lipid rafts and caveolae. Biochem Soc Trans 2005. [DOI: 10.1042/bst0331131] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
G-protein-coupled receptors (GPCRs) and post-GPCR signalling components are expressed at low overall abundance in plasma membranes, yet they evoke rapid, high-fidelity responses. Considerable evidence suggests that GPCR signalling components are organized together in membrane microdomains, in particular lipid rafts, enriched in cholesterol and sphingolipids, and caveolae, a subset of lipid rafts that also possess the protein caveolin, whose scaffolding domain may serve as an anchor for signalling components. Caveolae were originally identified based on their morphological appearance but their role in compartmentation of GPCR signalling has been primarily studied by biochemical techniques, such as subcellular fractionation and immunoprecipitation. Our recent studies obtained using both microscopic and biochemical methods with adult cardiac myocytes show expression of caveolin not only in surface sarcolemmal domains but also at, or close to, internal regions located at transverse tubules/sarcoplasmic reticulum. Other results show co-localization in lipid rafts/caveolae of AC (adenylyl cyclase), in particular AC6, certain GPCRs, G-proteins and eNOS (endothelial nitric oxide synthase; NOS3), which generates NO, a modulator of AC6. Existence of multiple caveolin-rich microdomains and their expression of multiple modulators of signalling strengthen the evidence that caveolins and lipid rafts/caveolae organize and regulate GPCR signal transduction in eukaryotic cells.
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Quinn PJ, Tessier C, Rainteau D, Koumanov KS, Wolf C. Structure and thermotropic phase behaviour of detergent-resistant membrane raft fractions isolated from human and ruminant erythrocytes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2005; 1713:5-14. [PMID: 15963456 DOI: 10.1016/j.bbamem.2005.04.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Revised: 04/26/2005] [Accepted: 04/28/2005] [Indexed: 11/23/2022]
Abstract
Detergent-resistant membrane raft fractions have been prepared from human, goat, and sheep erythrocyte ghosts using Triton X-100. The structure and thermotropic phase behaviour of the fractions have been examined by freeze-fracture electron microscopy and synchrotron X-ray diffraction methods. The raft fractions are found to consist of vesicles and multilamellar structures indicating considerable rearrangement of the original ghost membrane. Few membrane-associated particles typical of freeze-fracture replicas of intact erythrocyte membranes are observed in the fracture planes. Synchrotron X-ray diffraction studies during heating and cooling scans showed that multilamellar structures formed by stacks of raft membranes from all three species have d-spacings of about 6.5 nm. These structures can be distinguished from peaks corresponding to d-spacings of about 5.5 nm, which were assigned to scattering from single bilayer vesicles on the basis of the temperature dependence of their d-spacings compared with the multilamellar arrangements. The spacings obtained from multilamellar stacks and vesicular suspensions of raft membranes were, on average, more than 0.5 nm greater than corresponding arrangements of erythrocyte ghost membranes from which they were derived. The trypsinization of human erythrocyte ghosts results in a small decrease in lamellar d-spacing, but rafts prepared from trypsinized ghosts exhibit an additional lamellar repeat 0.4 nm less than a lamellar repeat coinciding with rafts prepared from untreated ghosts. The trypsinization of sheep erythrocyte ghosts results in the phase separation of two lamellar repeat structures (d=6.00; 5.77 nm), but rafts from trypsinized ghosts produce a diffraction band almost identical to rafts from untreated ghosts. An examination of the structure and thermotropic phase behaviour of the dispersions of total polar lipid extracts of sheep detergent-resistant membrane preparations showed that a reversible phase separation of an inverted hexagonal structure from coexisting lamellar phase takes place upon heating above about 30 degrees C. Non-lamellar phases are not observed in erythrocytes or detergent-resistant membrane preparations heated up to 55 degrees C, suggesting that the lamellar arrangement is imposed on these membrane lipids by interaction with non-lipid components of rafts and/or that the topology of lipids in the erythrocyte membrane survives detergent treatment.
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Affiliation(s)
- Peter J Quinn
- Department of Life Sciences, King's College London, 150 Stamford Street, London SE1 9NN, UK.
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Abstract
It is generally assumed that rafts exist in both the external and internal leaflets of the membrane, and that they overlap so that they are coupled functionally and structurally. However, the two monolayers of the plasma membrane of eukaryotic cells have different chemical compositions. This out-of-equilibrium situation is maintained by the activity of lipid translocases, which compensate for the slow spontaneous transverse diffusion of lipids. Thus rafts in the outer leaflet, corresponding to domains enriched in sphingomyelin and cholesterol, cannot be mirrored in the inner cytoplasmic leaflet. The extent to which lipids contribute to raft properties can be conveniently studied in giant unilamellar vesicles. In these, cholesterol can be seen to condense with saturated sphingolipids or phosphatidylcholine to form microm scale domains. However, such rafts fail to model biological rafts because they are symmetric, and because their membranes lack the mechanism that establishes this asymmetry, namely proteins. Biological rafts are in general of nm scale, and almost certainly differ in size and stability in inner and outer monolayers. Any coupling between rafts in the two leaflets, should it occur, is probably transient and dependent not upon the properties of lipids, but on transmembrane proteins within the rafts.
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Affiliation(s)
- Philippe F Devaux
- Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie 75005 Paris, France.
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Sunyach C, Jen A, Deng J, Fitzgerald KT, Frobert Y, Grassi J, McCaffrey MW, Morris R. The mechanism of internalization of glycosylphosphatidylinositol-anchored prion protein. EMBO J 2003; 22:3591-601. [PMID: 12853474 PMCID: PMC165614 DOI: 10.1093/emboj/cdg344] [Citation(s) in RCA: 224] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The mode of internalization of glycosylphosphatidylinositol-anchored proteins, lacking any cytoplasmic domain by which to engage adaptors to recruit them into coated pits, is problematical; that of prion protein in particular is of interest since its cellular trafficking appears to play an essential role in its pathogenic conversion. Here we demonstrate, in primary cultured neurons and the N2a neural cell line, that prion protein is rapidly and constitutively endocytosed. While still on the cell surface, prion protein leaves lipid 'raft' domains to enter non-raft membrane, from which it enters coated pits. The N-terminal domain (residues 23-107) of prion protein is sufficient to direct internalization, an activity dependent upon its initial basic residues (NH(2)-KKRPKP). The effect of this changing membrane environment upon the susceptibility of prion protein to pathogenic conversion is discussed.
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Affiliation(s)
- Claire Sunyach
- Molecular Neurobiology Group, MRC Centre for Developmental Neurobiology, King's College London Guy's Campus, London SEI 1UL, UK
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