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Baum JF, Bredegaard L, Herrera SA, Pomorski TG. Visualizing NBD-lipid Uptake in Mammalian Cells by Confocal Microscopy. Bio Protoc 2023; 13:e4771. [PMID: 37456343 PMCID: PMC10338633 DOI: 10.21769/bioprotoc.4771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 04/11/2023] [Accepted: 06/04/2023] [Indexed: 07/18/2023] Open
Abstract
Eukaryotic cells use a series of membrane transporters to control the movement of lipids across their plasma membrane. Several tools and techniques have been developed to analyze the activity of these transporters in the plasma membrane of mammalian cells. Among them, assays based on fluorescence microscopy in combination with fluorescent lipid probes are particularly suitable, allowing visualization of lipid internalization in living cells. Here, we provide a step-by-step protocol for mammalian cell culture, lipid probe preparation, cell labeling, and confocal imaging to monitor lipid internalization by lipid flippases at the plasma membrane based on lipid probes carrying a fluorophore at a short-chain fatty acid. The protocol allows studying a wide range of mammalian cell lines, to test the impact of gene knockouts on lipid internalization at the plasma membrane and changes in lipid uptake during cell differentiation. Key features Visualization and quantification of lipid internalization by lipid flippases at the plasma membrane based on confocal microscopy. Assay is performed on living adherent mammalian cells in culture. The protocol can be easily modified to a wide variety of mammalian cell lines.
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Affiliation(s)
- Julia F. Baum
- Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Lasse Bredegaard
- Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Sara Abad Herrera
- Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany
| | - Thomas Günther Pomorski
- Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
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2
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Gaibelet G, Tercé F, Allart S, Lebrun C, Collet X, Jamin N, Orlowski S. Fluorescent probes for detecting cholesterol-rich ordered membrane microdomains: entangled relationships between structural analogies in the membrane and functional homologies in the cell. AIMS BIOPHYSICS 2017. [DOI: 10.3934/biophy.2017.1.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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3
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Kishimoto T, Ishitsuka R, Kobayashi T. Detectors for evaluating the cellular landscape of sphingomyelin- and cholesterol-rich membrane domains. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:812-829. [PMID: 26993577 DOI: 10.1016/j.bbalip.2016.03.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 02/09/2016] [Accepted: 03/09/2016] [Indexed: 12/11/2022]
Abstract
Although sphingomyelin and cholesterol are major lipids of mammalian cells, the detailed distribution of these lipids in cellular membranes remains still obscure. However, the recent development of protein probes that specifically bind sphingomyelin and/or cholesterol provides new information about the landscape of the lipid domains that are enriched with sphingomyelin or cholesterol or both. Here, we critically summarize the tools to study distribution and dynamics of sphingomyelin and cholesterol. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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Affiliation(s)
| | - Reiko Ishitsuka
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Toshihide Kobayashi
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; INSERM U1060, Université Lyon 1, Villeurbanne 69621, France.
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4
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Adjili S, Favier A, Fargier G, Thomas A, Massin J, Monier K, Favard C, Vanbelle C, Bruneau S, Peyriéras N, Andraud C, Muriaux D, Charreyre MT. Biocompatible photoresistant far-red emitting, fluorescent polymer probes, with near-infrared two-photon absorption, for living cell and zebrafish embryo imaging. Biomaterials 2015; 46:70-81. [DOI: 10.1016/j.biomaterials.2014.12.026] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 11/29/2014] [Accepted: 12/20/2014] [Indexed: 12/12/2022]
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5
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Neufeld EB, O'Brien K, Walts AD, Stonik JA, Malide D, Combs CA, Remaley AT. The Human ABCG1 Transporter Mobilizes Plasma Membrane and Late Endosomal Non-Sphingomyelin-Associated-Cholesterol for Efflux and Esterification. BIOLOGY 2014; 3:866-91. [PMID: 25485894 PMCID: PMC4280515 DOI: 10.3390/biology3040866] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/22/2014] [Accepted: 11/26/2014] [Indexed: 11/16/2022]
Abstract
We have previously shown that GFP-tagged human ABCG1 on the plasma membrane (PM) and in late endosomes (LE) mobilizes sterol on both sides of the membrane lipid bilayer, thereby increasing cellular cholesterol efflux to lipid surfaces. In the present study, we examined ABCG1-induced changes in membrane cholesterol distribution, organization, and mobility. ABCG1-GFP expression increased the amount of mobile, non-sphingomyelin(SM)-associated cholesterol at the PM and LE, but not the amount of SM-associated-cholesterol or SM. ABCG1-mobilized non-SM-associated-cholesterol rapidly cycled between the PM and LE and effluxed from the PM to extracellular acceptors, or, relocated to intracellular sites of esterification. ABCG1 increased detergent-soluble pools of PM and LE cholesterol, generated detergent-resistant, non-SM-associated PM cholesterol, and increased resistance to both amphotericin B-induced (cholesterol-mediated) and lysenin-induced (SM-mediated) cytolysis, consistent with altered organization of both PM cholesterol and SM. ABCG1 itself resided in detergent-soluble membrane domains. We propose that PM and LE ABCG1 residing at the phase boundary between ordered (Lo) and disordered (Ld) membrane lipid domains alters SM and cholesterol organization thereby increasing cholesterol flux between Lo and Ld, and hence, the amount of cholesterol available for removal by acceptors on either side of the membrane bilayer for either efflux or esterification.
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Affiliation(s)
- Edward B Neufeld
- Lipoprotein Metabolism Section, Cardiovascular and Pulmonary Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Katherine O'Brien
- Lipid Trafficking Core, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Avram D Walts
- Lipid Trafficking Core, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| | - John A Stonik
- Lipoprotein Metabolism Section, Cardiovascular and Pulmonary Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Daniela Malide
- NHLBI Light Microscopy Core Facility, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Christian A Combs
- NHLBI Light Microscopy Core Facility, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Alan T Remaley
- Lipoprotein Metabolism Section, Cardiovascular and Pulmonary Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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6
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Taniguchi M, Okazaki T. The role of sphingomyelin and sphingomyelin synthases in cell death, proliferation and migration—from cell and animal models to human disorders. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:692-703. [DOI: 10.1016/j.bbalip.2013.12.003] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 12/06/2013] [Accepted: 12/09/2013] [Indexed: 12/16/2022]
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7
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Nusshold C, Uellen A, Bernhart E, Hammer A, Damm S, Wintersperger A, Reicher H, Hermetter A, Malle E, Sattler W. Endocytosis and intracellular processing of BODIPY-sphingomyelin by murine CATH.a neurons. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1831:1665-78. [PMID: 23973266 PMCID: PMC3807659 DOI: 10.1016/j.bbalip.2013.08.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 08/01/2013] [Accepted: 08/06/2013] [Indexed: 01/24/2023]
Abstract
Neuronal sphingolipids (SL) play important roles during axonal extension, neurotrophic receptor signaling and neurotransmitter release. Many of these signaling pathways depend on the presence of specialized membrane microdomains termed lipid rafts. Sphingomyelin (SM), one of the main raft constituents, can be formed de novo or supplied from exogenous sources. The present study aimed to characterize fluorescently-labeled SL turnover in a murine neuronal cell line (CATH.a). Our results demonstrate that at 4°C exogenously added BODIPY-SM accumulates exclusively at the plasma membrane. Treatment of cells with bacterial sphingomyelinase (SMase) and back-exchange experiments revealed that 55-67% of BODIPY-SM resides in the outer leaflet of the plasma membrane. Endocytosis of BODIPY-SM occurs via caveolae with part of internalized BODIPY-fluorescence ending up in the Golgi and the ER. Following endocytosis BODIPY-SM undergoes hydrolysis, a reaction substantially faster than BODIPY-SM synthesis from BODIPY-ceramide. RNAi demonstrated that both, acid (a)SMase and neutral (n)SMases contribute to BODIPY-SM hydrolysis. Finally, high-density lipoprotein (HDL)-associated BODIPY-SM was efficiently taken up by CATH.a cells. Our findings indicate that endocytosis of exogenous SM occurs almost exclusively via caveolin-dependent pathways, that both, a- and nSMases equally contribute to neuronal SM turnover and that HDL-like particles might represent physiological SM carriers/donors in the brain.
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Affiliation(s)
- Christoph Nusshold
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Andreas Uellen
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Eva Bernhart
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Astrid Hammer
- Institute of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Sabine Damm
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Andrea Wintersperger
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Helga Reicher
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Albin Hermetter
- Institute of Biochemistry, Graz University of Technology, Graz, Austria
| | - Ernst Malle
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Wolfgang Sattler
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
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8
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Essaka DC, White J, Rathod P, Whitmore CD, Hindsgaul O, Palcic MM, Dovichi NJ. Monitoring the uptake of glycosphingolipids in Plasmodium falciparum-infected erythrocytes using both fluorescence microscopy and capillary electrophoresis with laser-induced fluorescence detection. Anal Chem 2010; 82:9955-8. [PMID: 21043509 DOI: 10.1021/ac1021776] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The metabolism of glycosphingolipids by the malaria-causing parasite Plasmodium falciparum plays an important role in the progression of the disease. We report a new and highly sensitive method to monitor the uptake of glycosphingolipids in infected red blood cells (iRBCs). A tetramethylrhodamine-labeled glycosphingolipid (GM1-TMR) was used as a substrate. Uptake was demonstrated by fluorescence microscopy. The iRBCs were lysed with a 15% solution of saponin and washed with phosphate buffered saline to release intact parasites. The parasites were further lysed and the resulting homogenates were analyzed by capillary electrophoresis with laser-induced fluorescence detection. The lysate from erythrocytes infected at 1% parasitemia generated a signal 20 standard deviations larger than uninfected erythrocytes, which suggests that relatively low infection levels can be studied with this technique.
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Affiliation(s)
- David C Essaka
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, USA
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9
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Myelin, DIGs, and membrane rafts in the central nervous system. Prostaglandins Other Lipid Mediat 2009; 91:118-29. [PMID: 19379822 DOI: 10.1016/j.prostaglandins.2009.04.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Revised: 04/08/2009] [Accepted: 04/09/2009] [Indexed: 11/21/2022]
Abstract
Over the past 40 years our understanding of the organization of cell membranes has changed dramatically. Membranes are no longer viewed as a homogenous sea of phospholipids studded with randomly positioned islands of proteins. Our current view of the membrane involves the formation of small lipid clusters, comprised mainly of cholesterol and sphingolipids, known as membrane rafts. These lipid clusters apparently include and exclude specific proteins leading to the hypothesis that these domains (1) regulate cellular polarity and compartmentalization through trafficking and sorting, (2) provide platforms for cellular signaling and adhesion, and (3) function as cellular gate keepers. Tremendous controversy surrounds the concept of membrane rafts primarily because these small, highly dynamic entities are too small to be observed with traditional microscopic methods and the most utilized approach for raft analysis relies on poorly quantified, inconsistent biochemical extractions. New analytical approaches are being developed and applied to the study of membrane rafts and these techniques provide great promise for furthering our understanding of these enigmatic domains. In this review we will provide a brief summary of the current understanding of membrane rafts, utilizing the CNS myelin literature for illustrative purposes, and present caveats that should be considered when studying these domains.
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10
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Borisenko GG, Zaitseva MA, Chuvilin AN, Pozmogova GE. DNA modification of live cell surface. Nucleic Acids Res 2009; 37:e28. [PMID: 19158188 PMCID: PMC2651772 DOI: 10.1093/nar/gkn1034] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
We report a novel approach for the attachment of DNA fragments to the surface of live cells. By using fluorescence microscopy and flow cytometry we demonstrated that our synthetic conjugates of fatty acid with oligonucleotides can be incorporated in plasma membrane and then hybridized with complementary sequences at the cell surface. Method permits to control amount of immobilized DNA on the cell surface. All procedures can be completed within minutes and do not alter cell viability. Using this approach we tethered floating myeloid HL-60 cells to adherent A431 epitheliocytes in a sequence specific fashion. Thus, this method allows rapid and simple DNA multicoding of the cell surface and, therefore, opens new opportunities in manipulating with cell–cell interactions.
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Affiliation(s)
- Grigory G Borisenko
- Research Institute of Physical-Chemical Medicine, Russian Academy of Science, Moscow 119312, Russia.
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11
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Koivusalo M, Jansen M, Somerharju P, Ikonen E. Endocytic trafficking of sphingomyelin depends on its acyl chain length. Mol Biol Cell 2007; 18:5113-23. [PMID: 17942604 DOI: 10.1091/mbc.e07-04-0330] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
To study the principles of endocytic lipid trafficking, we introduced pyrene sphingomyelins (PyrSMs) with varying acyl chain lengths and domain partitioning properties into human fibroblasts or HeLa cells. We found that a long-chain, ordered-domain preferring PyrSM was targeted Hrs and Tsg101 dependently to late endosomal compartments and recycled to the plasma membrane in an NPC1- and cholesterol-dependent manner. A short-chain, disordered domain preferring PyrSM recycled more effectively, by using Hrs-, Tsg101- and NPC1-independent routing that was insensitive to cholesterol loading. Similar chain length-dependent recycling was observed for unlabeled sphingomyelins (SMs). The findings 1) establish acyl chain length as an important determinant in the endocytic trafficking of SMs, 2) implicate ESCRT complex proteins and NPC1 in the endocytic recycling of ordered domain lipids to the plasma membrane, and 3) introduce long-chain PyrSM as the first fluorescent lipid tracing this pathway.
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Affiliation(s)
- Mirkka Koivusalo
- Institute of Biomedicine/Anatomy and Institute of Biomedicine/Biochemistry, University of Helsinki, FIN-00014, Helsinki, Finland
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12
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Darroch PI, Dagan A, Granot T, He X, Gatt S, Schuchman EH. A lipid analogue that inhibits sphingomyelin hydrolysis and synthesis, increases ceramide, and leads to cell death. J Lipid Res 2005; 46:2315-24. [PMID: 16150832 DOI: 10.1194/jlr.m500136-jlr200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report the synthesis and characterization of a novel thiourea derivative of sphingomyelin (AD2765). In vitro assays using pure enzyme and/or cell extracts revealed that this compound inhibited the hydrolysis of BODIPY-conjugated or 14C-labeled sphingomyelin by acid sphingomyelinase and Mg2+-dependent neutral sphingomyelinase. Studies in normal human skin fibroblasts further revealed that AD2765 was taken up by cells and inhibited the hydrolysis of BODIPY-conjugated sphingomyelin in situ. In situ and in vitro studies also showed that this compound inhibited the synthesis of sphingomyelin from BODIPY-conjugated ceramide. The specificity of AD2765 for enzymes involved in sphingomyelin metabolism was demonstrated by the fact that it had no effect on the hydrolysis of BODIPY-conjugated ceramide by acid ceramidase or on the synthesis of BODIPY-conjugated glucosylceramide from BODIPY-conjugated ceramide. The overall effect of AD2765 on sphingomyelin metabolism was concentration-dependent, and treatment of normal human skin fibroblasts or cancer cells with this compound at concentrations > 10 microM led to an increase in cellular ceramide and cell death. Thus, AD2765 might be used to manipulate sphingomyelin metabolism in various ways, potentially to reduce substrate accumulation in cells from types A and B Niemann-Pick disease patients, and/or to affect the growth of human cancer cells.
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Affiliation(s)
- Peter I Darroch
- Department of Human Genetics, Mount Sinai School of Medicine, New York, NY 10029, USA
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13
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Abstract
Niemann-Pick type C, or NPC for short, is an early childhood disease exhibiting progressive neurological degeneration, associated with hepatosplenomegaly in some cases. The disease, at the cellular level, is a result of improper trafficking of lipids such as cholesterol and glycosphingolipids (GSLs) to lysosome-like storage organelles (LSOs), which become engorged with these lipids. It is believed that the initial defect in trafficking, whether of cholesterol or a GSL, results in an eventual traffic jam in these LSOs. This leads to the retention of not only other lipids, but also of transmembrane proteins that transiently associate with the late endosomes (LE) in normal cells, on their way to other cellular destinations such as the trans-Golgi network (TGN). In this review, we discuss the biophysical properties of lipids and cholesterol that might determine their intracellular itineraries, and how these itineraries are altered in NPC cells, which have defects in the proteins NPC1 or NPC2. We also discuss some potential therapeutic directions being suggested by recent research.
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Affiliation(s)
- Sushmita Mukherjee
- Department of Biochemistry, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA
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14
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Dahim M, Mizuno NK, Li XM, Momsen WE, Momsen MM, Brockman HL. Physical and photophysical characterization of a BODIPY phosphatidylcholine as a membrane probe. Biophys J 2002; 83:1511-24. [PMID: 12202376 PMCID: PMC1302249 DOI: 10.1016/s0006-3495(02)73921-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Lipids containing the dimethyl BODIPY fluorophore are used in cell biology because their fluorescence properties change with fluorophore concentration (C.-S. Chen, O. C. Martin, and R. E. Pagano. 1997. Biophys J. 72:37-50). The miscibility and steady-state fluorescence behavior of one such lipid, 1-palmitoyl-2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-sn-glycero-3-phosphocholine (PBPC), have been characterized in mixtures with 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC). PBPC packs similarly to phosphatidylcholines having a cis-unsaturated acyl chain and mixes nearly ideally with SOPC, apparently without fluorophore-fluorophore aggregation. Increasing PBPC mole fraction from 0.0 to 1.0 in SOPC membranes changes the emission characteristics of the probe in a continuous manner. Analysis of these changes shows that emission from the excited dimethyl BODIPY monomer self quenches with a critical radius of 25.9 A. Fluorophores sufficiently close (< or =13.7 A) at the time of excitation can form an excited dimer, emission from which depends strongly on total lipid packing density. Overall, the data show that PBPC is a reasonable physical substitute for other phosphatidylcholines in fluid membranes. Knowledge of PBPC fluorescence in lipid monolayers has been exploited to determine the two-dimensional concentration of SOPC in unilamellar, bilayer membranes.
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Affiliation(s)
- Mohammed Dahim
- The Hormel Institute, University of Minnesota, Austin, Minnesota 55912 USA
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15
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Abstract
Pyrene is one of the most frequently used lipid-linked fluorophores. Its most characteristic features are a long excited state lifetime and (local) concentration-dependent formation of excimers. Pyrene is also hydrophobic and thus does not significantly distort the conformation of the labeled lipid molecule. These characteristics make pyrene lipids well-suited for studies on a variety of biophysical phenomena like lateral diffusion, inter- or transbilayer movement of lipids and lateral organization of membranes. Pyrene lipids have also been widely employed to determine protein binding to membranes, lipid conformation and the activity of lipolytic enzymes. In cell biology, pyrene lipids are promising tools for studies on lipid trafficking and metabolism, as well as for microscopic mapping of membrane properties. The main disadvantage of pyrene lipids is the relatively large size of the fluorophore. Another disadvantage is that they require UV-excitation, which is not feasible with all microscopes.
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Affiliation(s)
- Pentti Somerharju
- Institute of Biomedicine, Biomedicum, Room C205b, Haartmaninkatu 8, P.O. Box 63, University of Helsinki, 00014 Helsinki, Finland.
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16
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Maier O, Oberle V, Hoekstra D. Fluorescent lipid probes: some properties and applications (a review). Chem Phys Lipids 2002; 116:3-18. [PMID: 12093532 DOI: 10.1016/s0009-3084(02)00017-8] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Odd as it may seem, experimental challenges in lipid research are often hampered by the simplicity of the lipid structure. Since, as in protein research, mutants or overexpression of lipids are not realistic, a considerable amount of lipid research relies on the use of tagged lipid analogues. However, given the size of an average lipid molecule, special care is needed for the selection of probes, since if the size and intramolecular localization of the probe is not specifically taken into account, it may dramatically affect the properties of the lipids. The latter is particularly important in cell biological studies of lipid trafficking and sorting, where the probed lipid should resemble its natural counterpart as closely as possible. On the other hand, for biophysical applications, these considerations may be less critical. Here we provide a brief overview of the application of several lipid probes in cell biological and biophysical research, and critically analyze their validity in the various fields.
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Affiliation(s)
- Olaf Maier
- Department of Membrane Cell Biology, Faculty of Medical Sciences, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
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17
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Tanhuanpää K, Cheng KH, Anttonen K, Virtanen JA, Somerharju P. Characteristics of pyrene phospholipid/gamma-cyclodextrin complex. Biophys J 2001; 81:1501-10. [PMID: 11509363 PMCID: PMC1301628 DOI: 10.1016/s0006-3495(01)75804-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Recently, it was demonstrated that gamma-cyclodextrins (gamma-CDs) greatly accelerates transfer of hydrophobic pyrene-labeled and other fluorescent phospholipid derivatives from vesicles to cells in culture (). To understand better the characteristics of this process, we studied the interaction of gamma-CD with pyrene-labeled phosphatidylcholines (PyrPCs) using a variety of physical methods. Either one or both of the acyl chains of PC was labeled with a pyrene moiety (monoPyrPCs and diPyrPCs, respectively), and the length of the labeled chain(s) varied from 4 to 14 carbons. Fluorescent binding assays showed that the association constant decreases strongly with increasing acyl chain length. PyrPC/gamma-CD stoichiometry was 1:2 for the shorter chain species, but changed to 1:3 when the acyl chain length exceeded 8 (diPyrPCs) or 10 (monoPyrPCs) carbons. The activation energy for the formation of diPyr(10)PC/gamma-CD complex was high, i.e., +92 kJ/mol, indicating that the phospholipid molecule has to fully emerge from the bilayer before complex formation can take place. The free energy, enthalpy, and entropy of transfer of monoPyrPC from bilayer to gamma-CD complex were close to zero. The absorption, Fourier transform infrared, and fluorescence spectral measurements and lifetime analysis indicated that the pyrene moiety lies inside the CD cavity and is conformationally restricted, particularly when the labeled chain is short. The acyl chains of a PyrPC molecule seem to share a CD cavity rather than occupy different ones. The present data provide strong evidence that the ability of gamma-CD to enhance intermembrane transfer of pyrene-labeled phospholipids is based on the formation of stoichiometric complexes in the aqueous phase. This information should help in designing CD derivatives that are more efficient lipid carriers then those available at present.
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Affiliation(s)
- K Tanhuanpää
- Institute of Biomedicine, Department of Biochemistry, University of Helsinki, Finland
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