1
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Jia N, Ganesan D, Guan H, Jeong YY, Han S, Nissenbaum M, Kusnecov AW, Cai Q. Mitochondrial bioenergetics stimulates autophagy for pathological tau clearance in tauopathy neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.12.579959. [PMID: 38405759 PMCID: PMC10888759 DOI: 10.1101/2024.02.12.579959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Hyperphosphorylation and aggregation of microtubule-associated tau is a pathogenic hallmark of tauopathies and a defining feature of Alzheimer's disease (AD). Pathological tau is targeted by autophagy for clearance, but autophagy dysfunction is indicated in tauopathy. While mitochondrial bioenergetic failure has been shown to precede the development of tau pathology, it is unclear whether energy metabolism deficiency is involved in tauopathy-related autophagy defects. Here, we reveal that stimulation of anaplerotic metabolism restores defective oxidative phosphorylation (OXPHOS) in tauopathy which, strikingly, leads to enhanced autophagy and pronounced tau clearance. OXPHOS-induced autophagy is attributed to increased ATP-dependent phosphatidylethanolamine biosynthesis in mitochondria. Excitingly, early bioenergetic stimulation boosts autophagy activity and reduces tau pathology, thereby counteracting memory impairment in tauopathy mice. Taken together, our study sheds light on a pivotal role of bioenergetic dysfunction in tauopathy-linked autophagy defects and suggests a new therapeutic strategy to prevent toxic tau buildup in AD and other tauopathies.
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2
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Eisenreichova A, Humpolickova J, Różycki B, Boura E, Koukalova A. Effects of biophysical membrane properties on recognition of phosphatidylserine, or phosphatidylinositol 4-phosphate by lipid biosensors LactC2, or P4M. Biochimie 2023; 215:42-49. [PMID: 37683994 DOI: 10.1016/j.biochi.2023.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 08/25/2023] [Accepted: 09/04/2023] [Indexed: 09/10/2023]
Abstract
Lipid biosensors are molecular tools used both in vivo and in vitro applications, capable of selectively detecting specific types of lipids in biological membranes. However, despite their extensive use, there is a lack of systematic characterization of their binding properties in various membrane conditions. The purpose of this study was to investigate the impact of membrane properties, such as fluidity and membrane charge, on the sensitivity of two lipid biosensors, LactC2 and P4M, to their target lipids, phosphatidylserine (PS) or phosphatidylinositol 4-phosphate (PI4P), respectively. Dual-color fluorescence cross-correlation spectroscopy, employed in this study, provided a useful technique to investigate interactions of these recombinant fluorescent biosensors with liposomes of varying compositions. The results of the study demonstrate that the binding of the LactC2 biosensor to low levels of PS in the membrane is highly supported by the presence of anionic lipids or membrane fluidity. However, at high PS levels, the presence of anionic lipids does not further enhance binding of LactC2. In contrast, neither membrane charge, nor membrane fluidity significantly affect the binding affinity of P4M to PI4P. These findings provide valuable insights into the role of membrane properties on the binding properties of lipid biosensors.
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Affiliation(s)
- Andrea Eisenreichova
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague 6, Czech Republic
| | - Jana Humpolickova
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague 6, Czech Republic
| | - Bartosz Różycki
- Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
| | - Evzen Boura
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague 6, Czech Republic
| | - Alena Koukalova
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague 6, Czech Republic.
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3
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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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4
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Abe M, Makino A, Murate M, Hullin-Matsuda F, Yanagawa M, Sako Y, Kobayashi T. PMP2/FABP8 induces PI(4,5)P 2-dependent transbilayer reorganization of sphingomyelin in the plasma membrane. Cell Rep 2021; 37:109935. [PMID: 34758297 DOI: 10.1016/j.celrep.2021.109935] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 08/20/2021] [Accepted: 10/13/2021] [Indexed: 12/11/2022] Open
Abstract
Sphingomyelin (SM) is a mammalian lipid mainly distributed in the outer leaflet of the plasma membrane (PM). We show that peripheral myelin protein 2 (PMP2), a member of the fatty-acid-binding protein (FABP) family, can localize at the PM and controls the transbilayer distribution of SM. Genetic screening with genome-wide small hairpin RNA libraries identifies PMP2 as a protein involved in the transbilayer movement of SM. A biochemical assay demonstrates that PMP2 is a phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2)-binding protein. PMP2 induces the tubulation of model membranes in a PI(4,5)P2-dependent manner, accompanied by the modification of the transbilayer membrane distribution of lipids. In the PM of PMP2-overexpressing cells, inner-leaflet SM is increased whereas outer-leaflet SM is reduced. PMP2 is a causative protein of Charcot-Marie-Tooth disease (CMT). A mutation in PMP2 associated with CMT increases its affinity for PI(4,5)P2, inducing membrane tubulation and the subsequent transbilayer movement of lipids.
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Affiliation(s)
- Mitsuhiro Abe
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan.
| | - Asami Makino
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Motohide Murate
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 67401 Illkirch, France
| | - Françoise Hullin-Matsuda
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Université de Lyon, CarMeN Laboratory, INSERM U1060, INRAE U1397, Université Claude Bernard Lyon 1, 69495 Pierre-Benite, France
| | - Masataka Yanagawa
- Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Yasushi Sako
- Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Toshihide Kobayashi
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 67401 Illkirch, France.
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5
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Yip AMH, Lo KKW. Luminescent rhenium(I), ruthenium(II), and iridium(III) polypyridine complexes containing a poly(ethylene glycol) pendant or bioorthogonal reaction group as biological probes and photocytotoxic agents. Coord Chem Rev 2018. [DOI: 10.1016/j.ccr.2018.01.021] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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6
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Sumi M, Makino A, Inaba T, Sako Y, Fujimori F, Greimel P, Kobayashi T. Photoswitchable phospholipid FRET acceptor: Detergent free intermembrane transfer assay of fluorescent lipid analogs. Sci Rep 2017; 7:2900. [PMID: 28588242 PMCID: PMC5460167 DOI: 10.1038/s41598-017-02980-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 04/20/2017] [Indexed: 12/20/2022] Open
Abstract
We have developed and characterized a novel photoswitchable phospholipid analog termed N-nitroBIPS-DPPG. The fluorescence can be switched on and off repeatedly with minimal photobleaching by UV or visible light exposure, respectively. The rather large photochromic head group is inserted deeply into the interfacial membrane region conferring a conical overall lipid shape, preference for a positive curvature and only minimal intermembrane transfer. Utilizing the switchable NBD fluorescence quenching ability of N-nitroBIPS-DPPG, a detergent free intermembrane transfer assay system for NBD modified lipids was demonstrated and validated. As NBD quenching can be turned off, total NBD associated sample fluorescence can be determined without the need of detergents. This not only reduces detergent associated systematic errors, but also simplifies assay handling and allows assay extension to detergent insoluble lipid species.
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Affiliation(s)
- Mariko Sumi
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan.,Graduate School of Humanities and Life Sciences, Tokyo Kasei University, 1-18-1, Kaga, Itabashi, Tokyo, 173-8602, Japan
| | - Asami Makino
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan.,Cellular Informatics Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Takehiko Inaba
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan.,Cellular Informatics Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Yasushi Sako
- Cellular Informatics Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Fumihiro Fujimori
- Graduate School of Humanities and Life Sciences, Tokyo Kasei University, 1-18-1, Kaga, Itabashi, Tokyo, 173-8602, Japan
| | - Peter Greimel
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan.
| | - Toshihide Kobayashi
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan. .,UMR 7213 CNRS, University of Strasbourg, 67401, Illkirch, France.
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7
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Liu HW, Law WHT, Lee LCC, Lau JCW, Lo KKW. Cyclometalated Iridium(III) Bipyridine-Phenylboronic Acid Complexes as Bioimaging Reagents and Luminescent Probes for Sialic Acids. Chem Asian J 2017; 12:1545-1556. [DOI: 10.1002/asia.201700359] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 04/13/2017] [Indexed: 12/31/2022]
Affiliation(s)
- Hua-Wei Liu
- Department of Biology and Chemistry; City University of Hong Kong; Tat Chee Avenue Kowloon Hong Kong P.R. China
| | - Wendell Ho-Tin Law
- Department of Biology and Chemistry; City University of Hong Kong; Tat Chee Avenue Kowloon Hong Kong P.R. China
| | - Lawrence Cho-Cheung Lee
- Department of Biology and Chemistry; City University of Hong Kong; Tat Chee Avenue Kowloon Hong Kong P.R. China
| | - Jonathan Chun-Wai Lau
- Department of Biology and Chemistry; City University of Hong Kong; Tat Chee Avenue Kowloon Hong Kong P.R. China
| | - Kenneth Kam-Wing Lo
- Department of Biology and Chemistry; City University of Hong Kong; Tat Chee Avenue Kowloon Hong Kong P.R. China
- State Key Laboratory of Millimeter Waves; City University of Hong Kong; Tat Chee Avenue Kowloon Hong Kong P.R. China
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8
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Human rhinovirus-induced inflammatory responses are inhibited by phosphatidylserine containing liposomes. Mucosal Immunol 2016; 9:1303-16. [PMID: 26906404 PMCID: PMC4883656 DOI: 10.1038/mi.2015.137] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 11/25/2015] [Indexed: 02/04/2023]
Abstract
Human rhinovirus (HRV) infections are major contributors to the healthcare burden associated with acute exacerbations of chronic airway disease, such as chronic obstructive pulmonary disease and asthma. Cellular responses to HRV are mediated through pattern recognition receptors that may in part signal from membrane microdomains. We previously found Toll-like receptor signaling is reduced, by targeting membrane microdomains with a specific liposomal phosphatidylserine species, 1-stearoyl-2-arachidonoyl-sn-glycero-3-phospho-L-serine (SAPS). Here we explored the ability of this approach to target a clinically important pathogen. We determined the biochemical and biophysical properties and stability of SAPS liposomes and studied their ability to modulate rhinovirus-induced inflammation, measured by cytokine production, and rhinovirus replication in both immortalized and normal primary bronchial epithelial cells. SAPS liposomes rapidly partitioned throughout the plasma membrane and internal cellular membranes of epithelial cells. Uptake of liposomes did not cause cell death, but was associated with markedly reduced inflammatory responses to rhinovirus, at the expense of only modest non-significant increases in viral replication, and without impairment of interferon receptor signaling. Thus using liposomes of phosphatidylserine to target membrane microdomains is a feasible mechanism for modulating rhinovirus-induced signaling, and potentially a prototypic new therapy for viral-mediated inflammation.
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9
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Arita Y, Nishimura S, Ishitsuka R, Kishimoto T, Ikenouchi J, Ishii K, Umeda M, Matsunaga S, Kobayashi T, Yoshida M. Targeting Cholesterol in a Liquid-Disordered Environment by Theonellamides Modulates Cell Membrane Order and Cell Shape. ACTA ACUST UNITED AC 2015; 22:604-10. [DOI: 10.1016/j.chembiol.2015.04.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 03/30/2015] [Accepted: 04/08/2015] [Indexed: 11/24/2022]
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10
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Law WHT, Leung KK, Lee LCC, Poon CS, Liu HW, Lo KKW. Cyclometalated Iridium(III) Bipyridyl-Phenylenediamine Complexes with Multicolor Phosphorescence: Synthesis, Electrochemistry, Photophysics, and Intracellular Nitric Oxide Sensing. ChemMedChem 2014; 9:1316-29. [DOI: 10.1002/cmdc.201400040] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Indexed: 11/08/2022]
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11
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Lo KKW, Law WHT, Chan JCY, Liu HW, Zhang KY. Photophysical and cellular uptake properties of novel phosphorescent cyclometalated iridium(iii) bipyridine d-fructose complexes. Metallomics 2013; 5:808-12. [DOI: 10.1039/c3mt20276c] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Li MJ, Wong KMC, Yi C, Yam VWW. New Ruthenium(II) Complexes Functionalized with Coumarin Derivatives: Synthesis, Energy-Transfer-Based Sensing of Esterase, Cytotoxicity, and Imaging Studies. Chemistry 2012; 18:8724-30. [DOI: 10.1002/chem.201103025] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Indexed: 12/27/2022]
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13
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Kay JG, Koivusalo M, Ma X, Wohland T, Grinstein S. Phosphatidylserine dynamics in cellular membranes. Mol Biol Cell 2012; 23:2198-212. [PMID: 22496416 PMCID: PMC3364182 DOI: 10.1091/mbc.e11-11-0936] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The distribution and dynamics of phosphatidylserine are studied in the plasma membrane and in organellar membranes of live cells using two novel fluorescent probes in combination with various biophysical techniques, including fluorescence correlation spectroscopy and single-particle tracking. Much has been learned about the role of exofacial phosphatidylserine (PS) in apoptosis and blood clotting using annexin V. However, because annexins are impermeant and unable to bind PS at low calcium concentration, they are unsuitable for intracellular use. Thus little is known about the topology and dynamics of PS in the endomembranes of normal cells. We used two new probes—green fluorescent protein (GFP)–LactC2, a genetically encoded fluorescent PS biosensor, and 1-palmitoyl-2-(dipyrrometheneboron difluoride)undecanoyl-sn-glycero-3-phospho-l-serine (TopFluor-PS), a synthetic fluorescent PS analogue—to examine PS distribution and dynamics inside live cells. The mobility of PS was assessed by a combination of advanced optical methods, including single-particle tracking and fluorescence correlation spectroscopy. Our results reveal the existence of a sizable fraction of PS with limited mobility, with cortical actin contributing to the confinement of PS in the plasma membrane. We were also able to measure the dynamics of PS in endomembrane organelles. By targeting GFP-LactC2 to the secretory pathway, we detected the presence of PS in the luminal leaflet of the endoplasmic reticulum. Our data provide new insights into properties of PS inside cells and suggest mechanisms to account for the subcellular distribution and function of this phospholipid.
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Affiliation(s)
- Jason G Kay
- Cell Biology, The Hospital for Sick Children, Toronto, ON, Canada
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14
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Han WQ, Xia M, Xu M, Boini KM, Ritter JK, Li NJ, Li PL. Lysosome fusion to the cell membrane is mediated by the dysferlin C2A domain in coronary arterial endothelial cells. J Cell Sci 2012; 125:1225-34. [PMID: 22349696 DOI: 10.1242/jcs.094565] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dysferlin has recently been reported to participate in cell membrane repair in muscle and other cells through lysosome fusion. Given that lysosome fusion is a crucial mechanism that leads to membrane raft clustering, the present study attempted to determine whether dysferlin is involved in this process and its related signalling, and explores the mechanism underlying dysferlin-mediated lysosome fusion in bovine coronary arterial endothelial cells (CAECs). We found that dysferlin is clustered in membrane raft macrodomains after Fas Ligand (FasL) stimulation as detected by confocal microscopy and membrane fraction flotation. Small-interfering RNA targeted to dysferlin prevented membrane raft clustering. Furthermore, the translocation of acid sphingomyelinase (ASMase) to membrane raft clusters, whereby local ASMase activation and ceramide production--an important step that mediates membrane raft clustering--was attenuated. Functionally, silencing of the dysferlin gene reversed FasL-induced impairment of endothelium-dependent vasodilation in isolated small coronary arteries. By monitoring fluorescence quenching or dequenching, silencing of the dysferlin gene was found to almost completely block lysosome fusion to plasma membrane upon FasL stimulation. Further studies to block C2A binding and silencing of AHNAK (a dysferlin C2A domain binding partner), showed that the dysferlin C2A domain is required for FasL-induced lysosome fusion to the cell membrane, ASMase translocation and membrane raft clustering. We conclude that dysferlin determines lysosome fusion to the plasma membrane through its C2A domain and it is therefore implicated in membrane-raft-mediated signaling and regulation of endothelial function in coronary circulation.
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Affiliation(s)
- Wei-Qing Han
- Department of Pharmacology & Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298, USA
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15
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Steunenberg P, Ruggi A, van den Berg NS, Buckle T, Kuil J, van Leeuwen FW, Velders AH. Phosphorescence Imaging of Living Cells with Amino Acid-Functionalized Tris(2-phenylpyridine)iridium(III) Complexes. Inorg Chem 2012; 51:2105-14. [DOI: 10.1021/ic201860s] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Peter Steunenberg
- Supramolecular Chemistry and
Technology, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - Albert Ruggi
- Supramolecular Chemistry and
Technology, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - Nynke S. van den Berg
- Division of Diagnostic Oncology, The Netherlands Cancer Institute, Plesmanlaan 121,
1066 CX, Amsterdam, The Netherlands; Interventional Molecular Imaging
Section, Department of Radiology, Leiden University Medical Center,
Leiden, The Netherlands
| | - Tessa Buckle
- Division of Diagnostic Oncology, The Netherlands Cancer Institute, Plesmanlaan 121,
1066 CX, Amsterdam, The Netherlands; Interventional Molecular Imaging
Section, Department of Radiology, Leiden University Medical Center,
Leiden, The Netherlands
| | - Joeri Kuil
- Division of Diagnostic Oncology, The Netherlands Cancer Institute, Plesmanlaan 121,
1066 CX, Amsterdam, The Netherlands; Interventional Molecular Imaging
Section, Department of Radiology, Leiden University Medical Center,
Leiden, The Netherlands
| | - Fijs W.B. van Leeuwen
- Division of Diagnostic Oncology, The Netherlands Cancer Institute, Plesmanlaan 121,
1066 CX, Amsterdam, The Netherlands; Interventional Molecular Imaging
Section, Department of Radiology, Leiden University Medical Center,
Leiden, The Netherlands
| | - Aldrik H. Velders
- Supramolecular Chemistry and
Technology, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
- BioNanoTechnology
group, Laboratory
of Physical Chemistry and Colloid Science Wageningen University, Dreijenplein
6, 6703 HB, Wageningen, The Netherlands
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16
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Sarantis H, Grinstein S. Monitoring Phospholipid Dynamics during Phagocytosis: Application of Genetically-Encoded Fluorescent Probes. Methods Cell Biol 2012; 108:429-44. [DOI: 10.1016/b978-0-12-386487-1.00019-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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17
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Lee PK, Law WHT, Liu HW, Lo KKW. Luminescent Cyclometalated Iridium(III) Polypyridine Di-2-picolylamine Complexes: Synthesis, Photophysics, Electrochemistry, Cation Binding, Cellular Internalization, and Cytotoxic Activity. Inorg Chem 2011; 50:8570-9. [DOI: 10.1021/ic201153d] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Pui-Kei Lee
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Wendell Ho-Tin Law
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Hua-Wei Liu
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Kenneth Kam-Wing Lo
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
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18
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Synthesis, properties, and live-cell imaging studies of luminescent cyclometalated iridium(III) polypyridine complexes containing two or three biotin pendants. Inorg Chem 2010; 48:6011-25. [PMID: 19480459 DOI: 10.1021/ic900412n] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Three luminescent cyclometalated iridium(III) bis-biotin complexes [Ir(N(wedge)C)(2)(N(wedge)N)](PF(6)) (HN(wedge)C = 2-(4-(N-(6-(biotinamido)hexyl)aminomethyl)phenyl)pyridine, HppyC6B, N(wedge)N = 2,2'-bipyridine, bpy (1); HN(wedge)C = 2-phenylpyridine, Hppy, N(wedge)N = 4,4'-bis((2-(biotinamido)ethyl)aminocarbonyl)-2,2'-bipyridine, bpyC2B2 (2); HN(wedge)C = Hppy, N(wedge)N = 4,4'-bis((2-((6-(biotinamido)hexanoyl)amino)ethyl)aminocarbonyl)-2,2'-bipyridine, bpyC2C6B2 (3)) and one tris-biotin complex [Ir(ppyC6B)(2)(bpyC6B)](PF(6)) (bpyC6B = 4-((6-(biotinamido)hexyl)aminocarbonyl)-4'-methyl-2,2'-bipyridine) (4) have been synthesized and characterized. The biotin-free complex [Ir(ppy)(2)(bpyC4)](PF(6)) (bpyC4 = 4,4'-bis(n-butylaminocarbonyl)-2,2'-bipyridine) (5) has also been prepared for comparison studies. Upon photoexcitation, all the complexes displayed intense and long-lived greenish-yellow to red triplet metal-to-ligand charge-transfer ((3)MLCT) (dpi (Ir) --> pi*(N(wedge)N)) emission in fluid solutions at room temperature and in low-temperature glass. Cyclic voltammetric studies revealed iridium(IV/III) oxidation at about +1.21 to + 1.29 V and diimine-based reductions at about -1.07 to -1.39 V versus SCE. The interactions of the bis-biotin and tris-biotin complexes with avidin have been studied by 4'-hydroxyazobenzene-2-carboxylic acid (HABA) assays, emission titrations, and dissociation assays. The possibility of these complexes as cross-linkers for avidin has been examined by microscopy studies using avidin-conjugated green fluororescent microspheres and size-exclusion HPLC analysis. Utilization of these luminescent iridium(III) biotin complexes in signal amplification has been demonstrated using avidin-coated nonfluorescent microspheres and complex 3 as an example. Additionally, the lipophilicity of all the complexes has been determined by reversed-phase HPLC. The cytotoxicity of these iridium(III) complexes toward the human cervix epithelioid carcinoma (HeLa) cell line has been evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assays. Furthermore, the cellular uptake of the complexes has been examined by ICP-MS, laser-scanning confocal microscopy, and flow cytometry.
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Lee PK, Liu HW, Yiu SM, Louie MW, Lo KKW. Luminescent cyclometallated iridium(III) bis(quinolylbenzaldehyde) diimine complexes--synthesis, photophysics, electrochemistry, protein cross-linking properties, cytotoxicity and cellular uptake. Dalton Trans 2010; 40:2180-9. [PMID: 20717588 DOI: 10.1039/c0dt00501k] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Four new luminescent cyclometallated iridium(III) bis(quinolylbenzaldehyde) diimine complexes [Ir(qba)(2)(N⁁N)](PF(6)) (Hqba = 4-(2-quinolyl)benzaldehyde, N⁁N = 2,2'-bipyridine, bpy (1); 1,10-phenanthroline, phen (2); 3,4,7,8-tetramethyl-1,10-phenanthroline, Me(4)-phen (3); 4,7-diphenyl-1,10-phenanthroline, Ph(2)-phen (4)) have been synthesised and characterised, and their electronic absorption, emission and electrochemical properties investigated. The X-ray crystal structures of complexes 1 and 2 have been determined. Upon irradiation, complexes 1-4 exhibited intense and long-lived orange-yellow emission in fluid solutions at 298 K and in alcohol glass at 77 K. The emission has been assigned to a triplet intra-ligand ((3)IL) excited state associated with the qba ligand, probably with mixing of some triplet metal-to-ligand charge-transfer ((3)MLCT) (dπ(Ir) →π*(qba)) character. Reductive amination reactions of complexes 1-4 with the protein bovine serum albumin (BSA) afforded the bioconjugates 1-BSA-4-BSA, respectively. Upon photoexcitation, these bioconjugates displayed intense and long-lived (3)MLCT (dπ(Ir) →π*(N⁁C)) emission in aqueous buffer at 298 K. The cross-linked nature of the Ir-BSA bioconjugates has been verified by SDS-PAGE. Additionally, the cytotoxicity of the complexes towards human cervix epithelioid carcinoma (HeLa) cells has been examined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assays, and the cellular uptake of complex 4 has been investigated by laser-scanning confocal microscopy and flow cytometry.
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Affiliation(s)
- Pui-Kei Lee
- Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong, People's Republic of China
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Li SY, Liu HW, Zhang K, Lo KW. Modification of Luminescent Iridium(III) Polypyridine Complexes with Discrete Poly(ethylene glycol) (PEG) Pendants: Synthesis, Emissive Behavior, Intracellular Uptake, and PEGylation Properties. Chemistry 2010; 16:8329-39. [DOI: 10.1002/chem.201000474] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Hailey DW, Rambold AS, Satpute-Krishnan P, Mitra K, Sougrat R, Kim PK, Lippincott-Schwartz J. Mitochondria supply membranes for autophagosome biogenesis during starvation. Cell 2010; 141:656-67. [PMID: 20478256 DOI: 10.1016/j.cell.2010.04.009] [Citation(s) in RCA: 1021] [Impact Index Per Article: 72.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 02/17/2010] [Accepted: 04/02/2010] [Indexed: 12/13/2022]
Abstract
Starvation-induced autophagosomes engulf cytosol and/or organelles and deliver them to lysosomes for degradation, thereby resupplying depleted nutrients. Despite advances in understanding the molecular basis of this process, the membrane origin of autophagosomes remains unclear. Here, we demonstrate that, in starved cells, the outer membrane of mitochondria participates in autophagosome biogenesis. The early autophagosomal marker, Atg5, transiently localizes to punctae on mitochondria, followed by the late autophagosomal marker, LC3. The tail-anchor of an outer mitochondrial membrane protein also labels autophagosomes and is sufficient to deliver another outer mitochondrial membrane protein, Fis1, to autophagosomes. The fluorescent lipid NBD-PS (converted to NBD-phosphotidylethanolamine in mitochondria) transfers from mitochondria to autophagosomes. Photobleaching reveals membranes of mitochondria and autophagosomes are transiently shared. Disruption of mitochondria/ER connections by mitofusin2 depletion dramatically impairs starvation-induced autophagy. Mitochondria thus play a central role in starvation-induced autophagy, contributing membrane to autophagosomes.
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Affiliation(s)
- Dale W Hailey
- The Eunice Kennedy Shriver National Institutes of Child Health and Human Development, 18 Library Drive, Bethesda, MD 20892, USA
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Leung SK, Kwok KY, Zhang KY, Lo KKW. Design of Luminescent Biotinylation Reagents Derived from Cyclometalated Iridium(III) and Rhodium(III) Bis(pyridylbenzaldehyde) Complexes. Inorg Chem 2010; 49:4984-95. [DOI: 10.1021/ic100092d] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Siu-Kit Leung
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Karen Ying Kwok
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Kenneth Yin Zhang
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Kenneth Kam-Wing Lo
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
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Organelle-specific, rapid induction of molecular activities and membrane tethering. Nat Methods 2010; 7:206-8. [PMID: 20154678 PMCID: PMC2860863 DOI: 10.1038/nmeth.1428] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Accepted: 01/18/2010] [Indexed: 01/13/2023]
Abstract
Using a series of novel chemically-inducible dimerization probes, we generated a system in which proteins were rapidly targeted to individual intracellular organelles. We demonstrated that a Ras GTPase can be activated at distinct intracellular locations and that membranes from two organelles, ER and mitochondria, can be inducibly tethered. Innovative techniques to rapidly perturb molecular activities and organelle-organelle communications at precise locations and timing will provide powerful strategies to dissect spatio-temporally complex biological processes.
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Luo S, Chen Q, Cebollero E, Xing D. Mitochondria: one of the origins for autophagosomal membranes? Mitochondrion 2009; 9:227-31. [PMID: 19398041 DOI: 10.1016/j.mito.2009.04.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Revised: 03/27/2009] [Accepted: 04/15/2009] [Indexed: 01/07/2023]
Abstract
Macroautophagy is a transport pathway to the lysosome/vacuole that contributes to the degradation of numerous intracellular components. Despite the recent advances achieved in the understanding of the molecular mechanism underlying macroautophagy, the membrane origin of autophagosomes, the hallmark of this process is still a mystery. It has been suggested that mitochondria may be one of the lipid sources for autophagosome formation and that possibly this organelle provides the phosphatidylethanolamine (PE) that covalently links to the members of the ubiquitin-like Atg8/microtubule-associated protein 1 light chain 3 (LC3) protein family. These lipidated proteins are inserted into the outer and inner surface of autophagosomes and are essential for the biogenesis of these large double-membrane vesicles. However, because PE is an integral component of all cellular membranes, designing appropriate experiments to determine the origin of the autophagosomal PE is not easy. In this review, we discuss the idea that mitochondria provide the pool of PE necessary for the autophagosome biogenesis and we propose some possible experimental approaches aimed to explore this possibility.
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Affiliation(s)
- Shiming Luo
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China
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Lau JSY, Lee PK, Tsang KHK, Ng CHC, Lam YW, Cheng SH, Lo KKW. Luminescent Cyclometalated Iridium(III) Polypyridine Indole Complexes—Synthesis, Photophysics, Electrochemistry, Protein-Binding Properties, Cytotoxicity, and Cellular Uptake. Inorg Chem 2008; 48:708-18. [DOI: 10.1021/ic801818x] [Citation(s) in RCA: 150] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jason Shing-Yip Lau
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Pui-Kei Lee
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Keith Hing-Kit Tsang
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Cyrus Ho-Cheong Ng
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Yun-Wah Lam
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Shuk-Han Cheng
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Kenneth Kam-Wing Lo
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
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26
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Poot M. Analysis of intracellular organelles by flow cytometry or microscopy. ACTA ACUST UNITED AC 2008; Chapter 9:Unit 9.4. [PMID: 18770757 DOI: 10.1002/0471142956.cy0904s14] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Functional analysis of cellular organelles can be accomplished by staining cells with suitable organelle-specific dyes and analyzing the fluorescence of the stained cells with a flow cytometer. With this methodology it is possible to resolve suspected heterogeneity in organelle function or content within a population of cells. Morphological information can be provided by quantitative microscopy (confocal microscope or video microscope with digital image-analysis system). The thirteen protocols cover flow cytometry and microscopy for both live and fixed cells.
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Affiliation(s)
- M Poot
- University of Washington, Seattle, Washington, USA
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27
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Abstract
Phagocytosis is an important component of innate and adaptive immunity. The formation of phagosomes and the subsequent maturation that capacitates them for pathogen elimination and antigen presentation are complex processes that involve signal transduction, cytoskeletal reorganization, and membrane remodeling. Lipids are increasingly appreciated to play a crucial role in these events. Sphingolipids, cholesterol, and glycerophospholipids, notably the phosphoinositides, are required for the segregation of signaling microdomains and for the generation of second messengers. They are also instrumental in the remodeling of the actin cytoskeleton and in directing membrane traffic. They accomplish these feats by congregating into liquid-ordered domains, by generating active metabolites that activate receptors, and by recruiting and anchoring specific protein ligands to the membrane, often altering their conformation and catalytic activity. A less appreciated role of acidic phospholipids is their contribution to the negative surface charge of the inner leaflet of the plasmalemma. The unique negativity of the inner aspect of the plasma membrane serves to attract and anchor key signaling and effector molecules that are required to initiate phagosome formation. Conversely, the loss of charge that accompanies phospholipid metabolism as phagosomes seal facilitates the dissociation of proteins and the termination of signaling and cytoskeleton assembly. In this manner, lipids provide a binary electrostatic switch to control phagocytosis.
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Affiliation(s)
- Tony Yeung
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
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Yotsumoto S, Kakiuchi T, Aramaki Y. Negatively charged phospholipids suppress IFN-gamma production in T cells. Biochem Biophys Res Commun 2005; 338:1719-25. [PMID: 16289110 DOI: 10.1016/j.bbrc.2005.10.179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Accepted: 10/29/2005] [Indexed: 12/31/2022]
Abstract
The effect of phospholipids on IFN-gamma production in mouse T cells was investigated. Phosphatidylserine (PS), which has a negatively charged head group, completely inhibited IFN-gamma production in splenic naïve T cells and antigen-dependent IFN-gamma production in Th1 clone 42-6A cells, whereas other phospholipids, which have neutrally charged head group, had no effect. The structural requirements for IFN-gamma inhibitory effects by PS were investigated, and dimyristoyl-PS (C14: 0) and dipalmitoyl-PS (C16: 0) had no effect on IFN-gamma production, and interestingly, distearoyl-PS (18: 0) increased IFN-gamma production. Dioleoyl-PS (C18: 1), dilinoleoyl-PS (C18: 2), and oleoyl-lyso-PS (C18: 1) completely inhibited IFN-gamma production. To clarify this mechanism, we focused on the stability of IFN-gamma mRNA, and the treatment of splenic naïve T cells with PS brought about 40% reductions in IFN-gamma mRNA expression in the presence of actinomycin D. Collectively, IFN-gamma inhibitory effects by PS are highly dependent on the molecular structure of PS and involve the decreasing of the stability of IFN-gamma mRNA.
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Affiliation(s)
- Satoshi Yotsumoto
- School of Pharmacy, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
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Sato SB, Ishii K, Makino A, Iwabuchi K, Yamaji-Hasegawa A, Senoh Y, Nagaoka I, Sakuraba H, Kobayashi T. Distribution and Transport of Cholesterol-rich Membrane Domains Monitored by a Membrane-impermeant Fluorescent Polyethylene Glycol-derivatized Cholesterol. J Biol Chem 2004; 279:23790-6. [PMID: 15026415 DOI: 10.1074/jbc.m313568200] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cholesterol-rich membrane domains function in various membrane events as diverse as signal transduction and membrane traffic. We studied the interaction of a fluorescein ester of polyethylene glycol-derivatized cholesterol (fPEG-Chol) with cholesterol-rich membranes both in cells and in model membranes. Unlike filipin and other cholesterol probes, this molecule could be applied as an aqueous dispersion to various samples. When added to live cells, fPEG-Chol distributed exclusively in the outer plasma membrane leaflet and was enriched in microdomains that dynamically clustered by the activation of receptor signaling. The surface-bound fPEG-Chol was slowly internalized via clathrin-independent pathway into endosomes together with lipid raft markers. Noteworthy, fPEG-Chol could be microinjected in the living cells in which we found Golgi apparatus as the sole major organelle to be labeled. PEG-Chol, thus, provides a novel, sensitive probe for unraveling the dynamics of cholesterol-rich microdomains in living cells.
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Birner R, Daum G. Biogenesis and cellular dynamics of aminoglycerophospholipids. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 225:273-323. [PMID: 12696595 DOI: 10.1016/s0074-7696(05)25007-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Aminoglycerophospholipids phosphatidylserine (PtdSer), phosphatidylethanolamine (PtdEtn), and phosphatidylcholine (PtdCho) comprise about 80% of total cellular phospholipids in most cell types. While the major function of PtdCho in eukaryotes and PtdEtn in prokaryotes is that of bulk membrane lipids, PtdSer is a minor component and appears to play a more specialized role in the plasma membrane of eukaryotes, e.g., in cell recognition processes. All three aminoglycerophospholipid classes are essential in mammals, whereas prokaryotes and lower eukaryotes such as yeast appear to be more flexible regarding their aminoglycerophospholipid requirement. Since different subcellular compartments of eukaryotes, namely the endoplasmic reticulum and mitochondria, contribute to the biosynthetic sequence of aminoglycerophospholipid formation, intracellular transport, sorting, and specific function of these lipids in different organelles are of special interest.
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Affiliation(s)
- Ruth Birner
- Institut für Biochemie, Technische Universität Graz, Petersgasse 12/2, A-8010 Graz, Austria
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31
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Heikinheimo L, Somerharju P. Translocation of pyrene-labeled phosphatidylserine from the plasma membrane to mitochondria diminishes systematically with molecular hydrophobicity: implications on the maintenance of high phosphatidylserine content in the inner leaflet of the plasma membrane. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1591:75-85. [PMID: 12183058 DOI: 10.1016/s0167-4889(02)00253-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To study the translocation of phosphatidylserine (PS) from plasma membrane to mitochondria, dipyrene PS molecules (diPyr(n)PS; n=acyl chain length) were introduced to the plasma membrane of baby hamster kidney cells (BHK cells) using either cyclodextrin-mediated monomer transfer or fusion of cationic vesicles. Translocation of diPyr(n)PS to mitochondria was assessed based on decarboxylation by mitochondrial PS decarboxylase (PSD). It was found that the rate of translocation diminishes systematically with acyl chain length (molecular hydrophobicity) of diPyr(n)PS. Using an in vitro assay, it was shown that the spontaneous translocation rates of long-chain diPyr(n)PS species are similar to those of common natural PS species, thus supporting the biological relevance of the data. These results, and other data arguing against the involvement of vesicular traffic and lipid transfer proteins, imply that spontaneous monomeric diffusion via the cytoplasm is the main mechanism of PS movement from the plasma membrane to mitochondria. This finding could explain why a major fraction of PS synthesized by BHK cells consists of hydrophobic species: such species have little tendency to efflux from the plasma membrane to mitochondria where they would be decarboxylated. Thus, adequate molecular hydrophobicity seems to be crucial for the maintenance of high PS content in the inner leaflet of the plasma membrane.
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Affiliation(s)
- Liisa Heikinheimo
- Department of Biochemistry, Institute of Biomedicine Biomedicum, University of Helsinki, Room C205b, P.O. Box 63, Haartmaninkatu 8, 00014 Helsinki, Finland
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Miyato Y, Ibuki Y, Ohyama H, Yamada T, Goto R. Phosphatidylserine induces apoptosis in CHO cells without mitochondrial dysfunction in a manner dependent on caspases other than caspases-1, -3, -8 and -9. FEBS Lett 2001; 504:73-7. [PMID: 11522300 DOI: 10.1016/s0014-5793(01)02771-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Treatment of Chinese hamster ovary K1 cells with phosphatidylserine (PS) caused typical apoptosis with distinct morphological and biochemical features in a dose- and time-dependent manner. However, unlike camptothecin-induced apoptosis, changes in mitochondrial transmembrane potential were not observed. In addition, cytochrome c release did not occur in PS-induced apoptosis. A pan caspase inhibitor, Z-VAD, significantly inhibited the apoptosis, but inhibitors of caspase-1, -3, -8 and -9 did not. Activities of caspase-1, -3, -8 and -9 were increased by treatment of the cells with camptothecin, but not with PS. These results suggest that PS-induced apoptosis occurs without the collapse of mitochondrial transmembrane potential and without the release of cytochrome c, in a manner independent of caspase-1, -3, -8 and -9.
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Affiliation(s)
- Y Miyato
- Laboratory of Radiation Biology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Japan
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Baba T, Rauch C, Xue M, Terada N, Fujii Y, Ueda H, Takayama I, Ohno S, Farge E, Sato SB. Clathrin-dependent and clathrin-independent endocytosis are differentially sensitive to insertion of poly (ethylene glycol)-derivatized cholesterol in the plasma membrane. Traffic 2001; 2:501-12. [PMID: 11422943 DOI: 10.1034/j.1600-0854.2001.20707.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We examined the effect of a cholesterol derivative, poly (ethylene glycol) cholesteryl ether on the structure/function of clathrin-coated pits and caveolae. Addition of the compound to cultured cells induced progressive smoothening of the surface. Markedly, when the incorporated amount exceeded 10% equivalent of the surface area, fluid pinocytosis, but not endocytosis of transferrin, became inhibited in K562 cells. In A431 cells, both clathrin-independent fluid phase uptake and the internalization of fluorescent cholera-toxin B through caveolae were inhibited with concomitant flattening of caveolae. In contrast, clathrin-mediated internalization of transferrin was not affected until the incorporated poly (ethylene glycol) cholesteryl ether exceeded 20% equivalent of the plasma membrane surface area, at which point opened clathrin-coated pits accumulated. The cells were ruptured upon further addition of poly (ethylene glycol) cholesteryl ether. We propose that the primary reason for the differential effect of poly (ethylene glycol) cholesteryl ether is that the bulk membrane phase and caveolae are both more elastic than the rigid clathrin-coated pits. We analyzed the results with the current mechanical model (Rauch and Farge, Biophys J 2000;78:3036-3047) and suggest here that the functional clathrin-lattice is much stiffer than typical phospholipid bilayers.
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Affiliation(s)
- T Baba
- Department of Anatomy, Yamanashi Medical University, Yamanashi 409-3898, Japan
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Tanhuanpää K, Somerharju P. gamma-cyclodextrins greatly enhance translocation of hydrophobic fluorescent phospholipids from vesicles to cells in culture. Importance of molecular hydrophobicity in phospholipid trafficking studies. J Biol Chem 1999; 274:35359-66. [PMID: 10585403 DOI: 10.1074/jbc.274.50.35359] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Short-chain, fluorescent derivatives are commonly used to investigate intracellular phospholipid trafficking. However, their use can yield misleading results because they, unlike the native species, can rapidly distribute between organelles due to their low hydrophobicity. On the other hand, hydrophobic derivatives are very difficult to introduce to cells and thus have hardly been used. Here we show that carboxyethylated gamma-cyclodextrin (CE-gamma-CD) greatly enhances transfer of a variety of hydrophobic fluorescent phospholipid derivatives from vesicles to cultured cells. Several lines of evidence indicate that CE-gamma-CD enhances transfer of lipid molecules by increasing their effective concentration in the aqueous phase, rather than by inducing membrane fusion or hemifusion. Incubation with CE-gamma-CD and donor lipid vesicles does not extract cholesterol or phospholipids from the cells or compromise plasma membrane intactness or long term cell viability. Using CE-gamma-CD-mediated transfer, we introduced hydrophobic pyrene-labeled phosphatidylserine to the plasma membrane of fibroblast cells and followed their distribution with time. In contrast to what has been previously observed for other, less hydrophobic species, transport of this lipid to the Golgi apparatus or mitochondria was not detected. Rather, much of this fluorescent PS remained in the plasma membrane or was incorporated to various endocytotic compartments. These findings indicate that the native, typically hydrophobic phosphatidylserine molecules efflux only very slowly via the cytoplasm to intracellular organelles. This helps to explain how cells can maintain a very high concentration of phosphatidylserine in the inner leaflet of their plasma membrane. Furthermore, the present results underline the importance of using hydrophobic analogues when studying intracellular trafficking of many phospholipid classes.
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Affiliation(s)
- K Tanhuanpää
- Institute of Biomedicine, Department of Medical Chemistry, University of Helsinki, Siltavuorenpenger 10 A, 00014 Helsinki, Finland
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Yon JO, Nakamura H, Ohta A, Takagi M. Incorporation of extracellular phospholipids and their effect on the growth and lipid metabolism of the Saccharomyces cerevisiae cho1/pss mutant. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1394:23-32. [PMID: 9767089 DOI: 10.1016/s0005-2760(98)00092-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The cho1/pss mutant of Saccharomyces cerevisiae, which is auxotrophic for choline or ethanolamine because of the deficiency in phosphatidylserine synthesis, grew in the presence of 0.05 mM phosphatidylcholine (PC) with octanoic acids (diC8PC) or decanoic acids (diC10PC), but not in the presence of PC with longer acyl residues. It did not grow in the presence of the soluble hydrolytic products of PC, phosphorylcholine or glycerophosphorylcholine, at comparable concentrations. Addition of 10 mM hemicholinium-3, a choline transport inhibitor, or disruption of the CTR gene, which encodes a choline transporter, inhibited the growth of the cho1/pss mutant in the presence of choline, but not in the presence of 0.1 mM diC8PC. Under diC8PC-supported growth conditions, octanoic acid was barely detectable in the cellular phospholipid fraction, but was recovered in the culture medium as the free acid, and the phosphatidylethanolamine (PE) content was low in comparison to the choline-supported conditions. These results suggest that PCs with short acyl residues were taken up by the cho1/pss mutant and remodeled as they were used, and that PCs with short acyl residues do not inhibit conversion of PE to PC. The current results provide a new direction in the analysis of intracellular phospholipid movement and metabolism in yeast.
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Affiliation(s)
- J O Yon
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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36
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Heikinheimo L, Somerharju P. Preferential decarboxylation of hydrophilic phosphatidylserine species in cultured cells. Implications on the mechanism of transport to mitochondria and cellular aminophospholipid species compositions. J Biol Chem 1998; 273:3327-35. [PMID: 9452450 DOI: 10.1074/jbc.273.6.3327] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In baby hamster kidney and other cultured cells the majority of phosphatidylethanolamine (PE) is synthesized from phosphatidylserine (PS) in a process which involves transport of PS from the endoplasmic reticulum to mitochondria and decarboxylation therein by PS decarboxylase. To study the mechanism of this transport process, we first determined the molecular species composition of PE and PS from baby hamster kidney and Chinese hamster ovary cells. Interestingly, the hydrophilic diacyl molecular species were found to be much more abundant in PE than in PS, suggesting that hydrophilic PS species may be more readily transported to mitochondria than the hydrophobic ones. To study this, we compared the rates of decarboxylation of different PS molecular species in these cells. The cells were pulse labeled with [3H]serine whereafter the distribution of the labels among PS and PE molecular species was determined by reverse phase high performance liquid chromatography and liquid scintillation counting. The hydrophilic PE species contained relatively much more 3H label than those of PS, which indicates that they are more readily decarboxylated than the hydrophobic ones. Control experiments showed that differences in [3H]PS and -PE molecular species profiles are not due to (i) incorporation of 3H label to some PE species via alternative pathways, (ii) differences in degradation or remodeling among species, or (iii) selective decarboxylation of PS molecular species by the enzyme. Therefore, hydrophilic PS species are indeed decarboxylated faster than the hydrophobic ones. The rate of decarboxylation decreased systematically with hydrophobicity, strongly suggesting that formation of so called activated monomers, i.e. lipid molecules perpendicularly displaced from the membrane (Jones, J. D., and Thompson, T. E. (1990) Biochemistry 29, 1593-1600), is the rate-limiting step in the transport of PS from the endoplasmic reticulum to mitochondria. The formation of activated monomers and thus the rate of transfer is probably greatly enhanced by frequent collisions between the two membranes which tend to be closely associated. The present data also provides a feasible explanation why hydrophilic molecular species in these cells are much more abundant in PE as compared with PS, its immediate precursor.
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Affiliation(s)
- L Heikinheimo
- Institute of Biomedicine, Department of Medical Chemistry, University of Helsinki, Helsinki, Finland
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37
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Nüssler F, Clague MJ, Herrmann A. Meta-stability of the hemifusion intermediate induced by glycosylphosphatidylinositol-anchored influenza hemagglutinin. Biophys J 1997; 73:2280-91. [PMID: 9370425 PMCID: PMC1181133 DOI: 10.1016/s0006-3495(97)78260-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Fusion between influenza virus and target membranes is mediated by the viral glycoprotein hemagglutinin (HA). Replacement of the transmembrane domain of HA with a glycosylphosphatidylinositol (GPI) membrane anchor allows lipid mixing but not the establishment of cytoplasmic continuity. This observation led to the proposal that the fusion mechanism passes through an intermediate stage corresponding to hemifusion between outer monolayers. We have used confocal fluorescence microscopy to study the movement of probes for specific bilayer leaflets of erythrocytes fusing with HA-expressing cells. N-Rh-PE and NBD-PC were used for specific labeling of the outer and inner membrane leaflet, respectively. In the case of GPI-HA-induced fusion, different behaviors of lipid transfer were observed, which include 1) exclusive movement of N-Rh-PE (hemifusion), 2) preferential movement of N-Rh-PE relative to NBD-PC, and 3) equal movement of both lipid analogs. The relative population of these intermediate states was dependent on the time after application of a low pH trigger for fusion. At early time points, hemifusion was more common and full redistribution of both bilayers was rare, whereas later full redistribution of both probes was frequently observed. In contrast to wild-type HA, the latter was not accompanied by mixing of the cytoplasmic marker Lucifer Yellow. We conclude that 1) the GPI-HA-mediated hemifusion intermediate is meta-stable and 2) expansion of an aqueous fusion pore requires the transmembrane and/or cytoplasmic domain of HA.
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Affiliation(s)
- F Nüssler
- Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, Institut für Biologie/Biophysik, Germany
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38
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Pomorski T, Muller P, Zimmermann B, Burger K, Devaux PF, Herrmann A. Transbilayer movement of fluorescent and spin-labeled phospholipids in the plasma membrane of human fibroblasts: a quantitative approach. J Cell Sci 1996; 109 ( Pt 3):687-98. [PMID: 8907713 DOI: 10.1242/jcs.109.3.687] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
All phospholipids in the plasma membrane of eukaryotic cells are subject to a slow passive transbilayer movement. In addition, aminophospholipids are recognized by the so-called aminophospholipid translocase, and are rapidly moved from the exoplasmic to the cytoplasmic leaflet of the plasma membrane at the expense of ATP hydrolysis. Though these principal pathways of transbilayer movement of phospholipids probably apply to all eukaryotic plasma membranes, studies of the actual kinetics of phospholipid redistribution have been largely confined to non-nucleated cells (erythrocytes). Experiments on nucleated cells are complicated by endocytosis and metabolism of the lipid probes inserted into the plasma membrane. Taking these complicating factors into account, we performed a detailed kinetic study of the transbilayer movement of short-chain fluorescent (N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl); NBD) and, for the first time, spin-labeled analogues of phosphatidylcholine (PC), -ethanolamine (PE), -serine (PS), and sphingomyelin (SM) in the plasma membrane of cultured human gingival fibroblasts. At 20 degrees C, the passive transbilayer diffusion of NBD analogues was very slow, and the choline-containing NBD analogues were internalized predominantly by endocytosis. Spin-labeled analogues of PC and SM showed higher passive transbilayer diffusion rates, and probably entered the cell by both passive transbilayer movement and endocytosis. In contrast, the rapid uptake of NBD- and spin-labeled aminophospholipid analogues could be mainly ascribed to the action of the aminophospholipid translocase, since it was inhibited by ATP depletion and N-ethylmaleimide pretreatment. The initial velocity of NBD-aminophospholipid translocation was eight to ten times slower than that of the corresponding spin-labeled lipid, and the half-times of redistribution of NBD-PS and spin-labeled PS were 7.2 and 3.6 minutes, respectively. Our data indicate that in human fibroblasts the initial velocity of aminophospholipid translocation is at least one order of magnitude higher than that in human erythrocytes, which should be sufficient to maintain the phospholipid asymmetry in the plasma membrane.
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Affiliation(s)
- T Pomorski
- Humboldt-Universitat zu Berlin, Mathematisch-Naturwissenschaftliche Fakultat I, Institut fur Biologie/Biophysik, Berlin, Germany
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39
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Phosphatidylserine dynamics and membrane biogenesis. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s1874-5245(96)80013-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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40
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Julien M, Tournier JF, Tocanne JF. Basic Fibroblast Growth Factor Modulates the Aminophospholipid Translocase Activity Present in the Plasma Membrane of Bovine Aortic Endothelial Cells. ACTA ACUST UNITED AC 1995. [DOI: 10.1111/j.1432-1033.1995.0287i.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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41
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Nolan JP, Magargee SF, Posner RG, Hammerstedt RH. Flow cytometric analysis of transmembrane phospholipid movement in bull sperm. Biochemistry 1995; 34:3907-15. [PMID: 7696254 DOI: 10.1021/bi00012a006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Fluorescent phospholipids are useful to investigate phospholipid dynamics in biological membranes. We used flow cytometry to investigate transbilayer phospholipid movement in live sperm cells. Acyl-labeled N-4-nitrobenzo-2-oxa-1,3-diazole (NBD) -phosphatidylcholine (-PC), -phosphatidylethanolamine (-PE), or -phosphatidylserine (-PS) were incorporated into sperm cells, and the transbilayer location was determined by extraction of probe from cell with excess bovine serum albumin (BSA) or by chemical destruction of probe by sodium dithionite. Using these methods, we have measured the head group specific outer leaflet to inner leaflet movement (flip) of the aminophospholipids NBD-PS and NBD-PE. The fluorescent phospholipids moved inward across the plasma membrane with half-times of 1.8, 2.5, and 11.2 min, for NBD-PS, NBD-PE, and NBD-PC and reached apparent equilibrium levels of 88%, 94%, and 32% inside, respectively. The inward movement of NBD-PE was inhibited by sulfhydryl reagents, elevated intracellular Ca2+, and depletion of cellular ATP. Analysis of the kinetics of NBD-PE and -PS extraction by BSA allows determination of the rates for outward movement (flop) across the plasma membrane. Half-times for flop were 4.7 and 4.5 min for NBD-PS and -PE, respectively. Based on these measurements, a simple model of NBD-phospholipid equilibria was developed and fit to the kinetic data. Computer-generated fits reflected major features of the experimental data and provide a potential tool for predicting the dynamics of endogenous lipids.
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Affiliation(s)
- J P Nolan
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park 16802
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42
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Hanada K, Pagano RE. A Chinese hamster ovary cell mutant defective in the non-endocytic uptake of fluorescent analogs of phosphatidylserine: isolation using a cytosol acidification protocol. J Cell Biol 1995; 128:793-804. [PMID: 7876305 PMCID: PMC2120400 DOI: 10.1083/jcb.128.5.793] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Transmembrane movement of phosphatidylserine (PS) and various PS analogs at the plasma membrane is thought to occur by an ATP-dependent, protein-mediated process. To isolate mutant CHO cells defective in this activity, we first obtained conditions which inhibited the endocytic, but not the non-endocytic pathway of lipid internalization since PS may enter cells by a combination of these two pathways. We found that acidic treatment of cells, which blocks clathrin-dependent endocytosis, enhanced the energy-dependent uptake of 1-palmitoyl-2-(6-[(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]caproyl -sn- glycero-3-phosphoserine (C6-NBD-PS) in CHO cells from donor vesicles (liposomes) by about twofold. Control experiments demonstrated that the enhanced uptake of C6-NBD-PS at acidic pH was not due to: (a) an increase in the capacity of the plasma membrane to incorporate C6-NBD-PS from the donor vesicles; (b) a decrease in the rate of loss of C6-NBD-PS from the cells; or (c) fusion or engulfment of the donor vesicles. When cytosolic acidification (to pH 6.3) was imposed without acidification of the extracellular medium, C6-NBD-PS uptake by intact cells was increased by about 50% compared to control values determined in the absence of acidification. These results suggested that a protein and energy dependent system(s) for transbilayer movement of the fluorescent PS was stimulated by cytosolic acidification. A screening method for mutant cells defective in the non-endocytic uptake of fluorescent PS analogs with replica cell colonies at acidic pH was then devised. After selection of mutagenized CHO-K1 cells by in situ screening, we obtained a mutant cell line in which uptake of fluorescent PS analogs was reduced to about 25% of the wild type level at either pH 6.0 or 7.4. Control experiments demonstrated that the reduced uptake of fluorescent PS analogs in the mutant cells was unrelated to multidrug resistance, and that endocytosis of another plasma membrane lipid marker occurred normally in the mutant cells. These results suggested that a non-endocytic pathway responsible for uptake of fluorescent PS analogs was specifically affected in the mutant cells.
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Affiliation(s)
- K Hanada
- Department of Embryology, Carnegie Institution of Washington, Baltimore, Maryland 21210
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43
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Moreau P, Cassagne C. Phospholipid trafficking and membrane biogenesis. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1197:257-90. [PMID: 7819268 DOI: 10.1016/0304-4157(94)90010-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- P Moreau
- URA 1811 CNRS, IBGC, University of Bordeaux II, France
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44
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45
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Martin OC, Pagano RE. Internalization and sorting of a fluorescent analogue of glucosylceramide to the Golgi apparatus of human skin fibroblasts: utilization of endocytic and nonendocytic transport mechanisms. J Cell Biol 1994; 125:769-81. [PMID: 8188745 PMCID: PMC2120081 DOI: 10.1083/jcb.125.4.769] [Citation(s) in RCA: 134] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We examined the uptake and intracellular transport of the fluorescent glucosylceramide analogue N-[5-(5,7-dimethyl BODIPYTM)-1-pentanoyl]-glucosyl sphingosine (C5-DMB-GlcCer) in human skin fibroblasts, and we compared its behavior to that of the corresponding fluorescent analogues of sphingomyelin, galactosylceramide, and lactosylceramide. All four fluorescent analogues were readily transferred from defatted BSA to the plasma membrane during incubation at 4 degrees C. When cells treated with C5-DMB-GlcCer were washed, warmed to 37 degrees C, and subsequently incubated with defatted BSA to remove fluorescent lipid at the cell surface, strong fluorescence was observed at the Golgi apparatus, as well as weaker labeling at the nuclear envelope and other intracellular membranes. Similar results were obtained with C5-DMB-galactosylceramide, except that labeling of the Golgi apparatus was weaker than with C5-DMB-GlcCer. Internalization of C5-DMB-GlcCer was not inhibited by various treatments, including ATP depletion or warming to 19 degrees C, and biochemical analysis demonstrated that the lipid was not metabolized during its internalization. However, accumulation of C5-DMB-GlcCer at the Golgi apparatus was reduced when cells were treated with a nonfluorescent analogue of glucosylceramide, suggesting that accumulation of C5-DMB-GlcCer at the Golgi apparatus was a saturable process. In contrast, cells treated with C5-DMB-analogues of sphingomyelin or lactosylceramide internalized the fluorescent lipid into a punctate pattern of fluorescence during warming at 37 degrees C, and this process was temperature and energy dependent. These results with C5-DMB-sphingomyelin and C5-DMB-lactosylceramide were analogous to those obtained with another fluorescent analogue of sphingomyelin in which labeling of endocytic vesicles and plasma membrane lipid recycling were documented (Koval, M., and R. E. Pagano. 1990. J. Cell Biol. 111:429-442). Incubation of perforated cells with C5-DMB-sphingomyelin resulted in prominent labeling of the nuclear envelope and other intracellular membranes, similar to the pattern observed with C5-DMB-GlcCer in intact cells. These observations are consistent with the transbilayer movement of fluorescent analogues of glucosylceramide and galactosylceramide at the plasma membrane and early endosomes of human skin fibroblasts, and suggest that both endocytic and nonendocytic pathways are used in the internalization of these lipids from the plasma membrane.
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Affiliation(s)
- O C Martin
- Department of Embryology, Carnegie Institution of Washington, Baltimore, Maryland 21210-3399
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46
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Tocanne JF, Dupou-Cézanne L, Lopez A. Lateral diffusion of lipids in model and natural membranes. Prog Lipid Res 1994; 33:203-37. [PMID: 8022844 DOI: 10.1016/0163-7827(94)90027-2] [Citation(s) in RCA: 131] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- J F Tocanne
- CNRS, Département III: Glycoconjugués et Biomembranes, Toulouse, France
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47
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Kleuser B, Schmidt N, Gercken G. Synthesis of 1-O-alkyl-sn-glycerols and fluorescently labeled analogs from as precursor. Chem Phys Lipids 1993. [DOI: 10.1016/0009-3084(93)90036-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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48
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Jasińska R, Zborowski J, Somerharju P. Intramitochondrial distribution and transport of phosphatidylserine and its decarboxylation product, phosphatidylethanolamine. Application of pyrene-labeled species. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1152:161-70. [PMID: 8399295 DOI: 10.1016/0005-2736(93)90243-s] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
To investigate the mechanism of intramitochondrial translocation of phosphatidylserine and its decarboxylation product, phosphatidylethanolamine, the distribution of these lipids between the outer (OM) and inner (IM) mitochondrial membranes, as well as their transversal and lateral distribution in OM were studied. Fluorescent, pyrenyl derivatives of phosphatidylserine (PyrxPS) and phosphatidylethanolamine (PyrxPE) species were employed because they allow: (i), direct monitoring of PS (and PE) loading to the mitochondria; (ii) assay of PS decarboxylation by high-performance liquid chromatography with fluorescence detection and (iii), determination of the lateral distributions of PS and PE within the mitochondrial membranes. All PyrxPS species tested were efficiently decarboxylated by the solubilized decarboxylase and thus the distribution of the endogenous PE could be also studied. When the PyrxPS species were loaded to isolated mitochondria very little, if any, of the loaded PyrxPS or of the PyrxPE product was found in IM independent of the time and temperature of incubation, strongly suggesting that these lipids either never enter IM or their residence there is only transient. When mitochondria preloaded with Pyr4PS were incubated with an excess of acceptor vesicles in the presence of the lipid transfer protein, 80% of Pyr4PS and 30-40% of the Pyr4PE product were transported to the acceptor vesicles, indicating that at least corresponding fractions of these lipid were located in, or were in rapid equilibrium with the outer leaflet of OM. Since the decarboxylase is located in the inner membrane, these results signify that both PS and PE must be able to move readily across OM. Determination of the excimer to monomer ratio as the function of pyrenyl lipid concentration in mitochondria (i.e., OM) gave parallel results for PyrxPS and -PE species suggesting the lateral distribution of PS and PE in OM is similar and thus there is no specific enrichment of PS to the contact sites. To investigate the mechanism of PS transport from the outer leaflet to the decarboxylation site, the influence of PyrxPS hydrophobicity, i.e., pyrenylacyl chain length, on the rate of decarboxylation was determined. The variation of the length of the pyrenyl acyl chain from 4 to 12 carbons did not significantly affect the rate of PyrxPS decarboxylation in intact mitochondria, indicating that the transport of PS from the outer leaflet of OM to the site of decarboxylation takes place by lateral diffusion rather than by spontaneous or protein-mediated transport. The implications of these findings on the mechanism of intramitochondrial transport of PS and PE are discussed in terms of alternative models.
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Affiliation(s)
- R Jasińska
- Department of Cellular Biochemistry, Nencki Institute on Experimental Biology, Warsaw, Poland
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49
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Abstract
The lipid composition of cellular membranes may seem unnecessarily complex. However, the lipid composition of each membrane is carefully regulated by local metabolism and specificity in transport, marking the functional significance for the cell. Recent research has revealed unexpected discoveries concerning the topology of lipid synthesis, specificity in lipid transport, and the function of lipid and protein microdomains in sorting.
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Affiliation(s)
- G van Meer
- Department of Cell Biology, Medical School, University of Utrecht, The Netherlands
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50
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Gregorio CC, Kubo RT, Bankert RB, Repasky EA. Translocation of spectrin and protein kinase C to a cytoplasmic aggregate upon lymphocyte activation. Proc Natl Acad Sci U S A 1992; 89:4947-51. [PMID: 1375753 PMCID: PMC49205 DOI: 10.1073/pnas.89.11.4947] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
We have previously reported that mammalian tissue lymphocytes exhibit significant heterogeneity with respect to the subcellular distribution of spectrin and that this phenomenon may result from a dynamic behavior of spectrin in response to activation signals. Here, we further characterize the involvement of spectrin in lymphocyte activation by examining its relationship with protein kinase C (PKC). PKC isoenzymes are a family of cytosolic kinases that translocate from the soluble to particulate fraction upon cell stimulation. It is reported here that activation of lymph node T cells through the antigen-specific receptor, or direct activation of PKC by phorbol esters, results in a striking increase in cells expressing a cytoplasmic aggregate of spectrin. Additionally, a concurrent increase in cells expressing aggregates of the beta II isozyme of PKC is observed. Immunofluorescence staining revealed that spectrin and PKC beta II are colocalized in untreated lymphocytes and that these two proteins are coincidently translocated to the same focal aggregate within the cytoplasm following stimulation. This redistribution of spectrin and PKC beta is blocked by pretreatment with calphostin C, a specific inhibitor of PKC. Solubility studies showed that there is an increase of both proteins in the detergent-insoluble fraction of lymphocytes upon activation, and immunoprecipitation studies indicated that the soluble form of these molecules may be associated directly or indirectly as part of a complex of proteins. These data indicate that the positioning of the spectrin-based cytoskeleton is sensitive to activation signals and may play a role in the function or positioning of PKC beta II.
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Affiliation(s)
- C C Gregorio
- Department of Molecular Immunology, Roswell Park Cancer Institute, Buffalo, NY 14263
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