51
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Abstract
Tissue macrophages rapidly recognize and engulf apoptotic cells. These events require the display of so-called eat-me signals on the apoptotic cell surface, the most fundamental of which is phosphatidylserine (PtdSer). Externalization of this phospholipid is catalysed by scramblase enzymes, several of which are activated by caspase cleavage. PtdSer is detected both by macrophage receptors that bind to this phospholipid directly and by receptors that bind to a soluble bridging protein that is independently bound to PtdSer. Prominent among the latter receptors are the MER and AXL receptor tyrosine kinases. Eat-me signals also trigger macrophages to engulf virus-infected or metabolically traumatized, but still living, cells, and this 'murder by phagocytosis' may be a common phenomenon. Finally, the localized presentation of PtdSer and other eat-me signals on delimited cell surface domains may enable the phagocytic pruning of these 'locally dead' domains by macrophages, most notably by microglia of the central nervous system.
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Affiliation(s)
- Greg Lemke
- Molecular Neurobiology Laboratory, Immunobiology and Microbial Pathogenesis Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, USA.
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52
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Nguyen VP, Dixson AC, Barrera FN. The Effect of Phosphatidylserine on a pH-Responsive Peptide Is Defined by Its Noninserting End. Biophys J 2019; 117:659-667. [PMID: 31400916 PMCID: PMC6712489 DOI: 10.1016/j.bpj.2019.07.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/26/2019] [Accepted: 07/15/2019] [Indexed: 02/08/2023] Open
Abstract
The acidity-triggered rational membrane (ATRAM) peptide was designed to target acidic diseases such as cancer. An acidic extracellular medium, such as that found in aggressive tumors, drives the protonation of the glutamic acids in ATRAM, leading to the membrane translocation of its C-terminus and the formation of a transmembrane helix. Compared to healthy cells, cancerous cells often increase exposure of the negatively charged phosphatidylserine (PS) on the outer leaflet of the plasma membrane. Here we use a reconstituted vesicle system to explore how PS influences the interaction of ATRAM with membranes. To explore this, we used two new variants of ATRAM, termed K2-ATRAM and Y-ATRAM, with small modifications at the noninserting N-terminus. We observed that the effect of PS on the membrane insertion pK and lipid partitioning hinged on the sequence of the noninserting end. Our data additionally indicate that the effect of PS on the insertion pK does not merely depend on electrostatics, but it is multifactorial. Here we show how small sequence changes can impact the interaction of a peptide with membranes of mixed lipid composition. These data illustrate how model studies using neutral bilayers, which do not mimic the negative charge found in the plasma membrane of cancer cells, may fail to capture important aspects of the interaction of anticancer peptides with tumor cells. This information can guide the design of therapeutic peptides that target the acidic environments of different diseased tissues.
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Affiliation(s)
- Vanessa P Nguyen
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee
| | - Andrew C Dixson
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee
| | - Francisco N Barrera
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee.
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53
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Fabiani C, Antollini SS. Alzheimer's Disease as a Membrane Disorder: Spatial Cross-Talk Among Beta-Amyloid Peptides, Nicotinic Acetylcholine Receptors and Lipid Rafts. Front Cell Neurosci 2019; 13:309. [PMID: 31379503 PMCID: PMC6657435 DOI: 10.3389/fncel.2019.00309] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 06/25/2019] [Indexed: 12/17/2022] Open
Abstract
Biological membranes show lateral and transverse asymmetric lipid distribution. Cholesterol (Chol) localizes in both hemilayers, but in the external one it is mostly condensed in lipid-ordered microdomains (raft domains), together with saturated phosphatidyl lipids and sphingolipids (including sphingomyelin and glycosphingolipids). Membrane asymmetries induce special membrane biophysical properties and behave as signals for several physiological and/or pathological processes. Alzheimer’s disease (AD) is associated with a perturbation in different membrane properties. Amyloid-β (Aβ) plaques and neurofibrillary tangles of tau protein together with neuroinflammation and neurodegeneration are the most characteristic cellular changes observed in this disease. The extracellular presence of Aβ peptides forming senile plaques, together with soluble oligomeric species of Aβ, are considered the major cause of the synaptic dysfunction of AD. The association between Aβ peptide and membrane lipids has been extensively studied. It has been postulated that Chol content and Chol distribution condition Aβ production and posterior accumulation in membranes and, hence, cell dysfunction. Several lines of evidence suggest that Aβ partitions in the cell membrane accumulate mostly in raft domains, the site where the cleavage of the precursor AβPP by β- and γ- secretase is also thought to occur. The main consequence of the pathogenesis of AD is the disruption of the cholinergic pathways in the cerebral cortex and in the basal forebrain. In parallel, the nicotinic acetylcholine receptor has been extensively linked to membrane properties. Since its transmembrane domain exhibits extensive contacts with the surrounding lipids, the acetylcholine receptor function is conditioned by its lipid microenvironment. The nicotinic acetylcholine receptor is present in high-density clusters in the cell membrane where it localizes mainly in lipid-ordered domains. Perturbations of sphingomyelin or cholesterol composition alter acetylcholine receptor location. Therefore, Aβ processing, Aβ partitioning, and acetylcholine receptor location and function can be manipulated by changes in membrane lipid biophysics. Understanding these mechanisms should provide insights into new therapeutic strategies for prevention and/or treatment of AD. Here, we discuss the implications of lipid-protein interactions at the cell membrane level in AD.
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Affiliation(s)
- Camila Fabiani
- Instituto de Investigaciones Bioquímicas de Bahía Blanca CONICET-UNS, Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Silvia S Antollini
- Instituto de Investigaciones Bioquímicas de Bahía Blanca CONICET-UNS, Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina
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54
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Moreau D, Vacca F, Vossio S, Scott C, Colaco A, Paz Montoya J, Ferguson C, Damme M, Moniatte M, Parton RG, Platt FM, Gruenberg J. Drug-induced increase in lysobisphosphatidic acid reduces the cholesterol overload in Niemann-Pick type C cells and mice. EMBO Rep 2019; 20:e47055. [PMID: 31267706 PMCID: PMC6607015 DOI: 10.15252/embr.201847055] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 04/12/2019] [Accepted: 04/23/2019] [Indexed: 12/26/2022] Open
Abstract
Most cells acquire cholesterol by endocytosis of circulating low-density lipoproteins (LDLs). After cholesteryl ester de-esterification in endosomes, free cholesterol is redistributed to intracellular membranes via unclear mechanisms. Our previous work suggested that the unconventional phospholipid lysobisphosphatidic acid (LBPA) may play a role in modulating the cholesterol flux through endosomes. In this study, we used the Prestwick library of FDA-approved compounds in a high-content, image-based screen of the endosomal lipids, lysobisphosphatidic acid and LDL-derived cholesterol. We report that thioperamide maleate, an inverse agonist of the histamine H3 receptor HRH3, increases highly selectively the levels of lysobisphosphatidic acid, without affecting any endosomal protein or function that we tested. Our data also show that thioperamide significantly reduces the endosome cholesterol overload in fibroblasts from patients with the cholesterol storage disorder Niemann-Pick type C (NPC), as well as in liver of Npc1-/- mice. We conclude that LBPA controls endosomal cholesterol mobilization and export to cellular destinations, perhaps by fluidifying or buffering cholesterol in endosomal membranes, and that thioperamide has repurposing potential for the treatment of NPC.
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Affiliation(s)
- Dimitri Moreau
- Department of BiochemistryUniversity of GenevaGeneva 4Switzerland
| | - Fabrizio Vacca
- Department of BiochemistryUniversity of GenevaGeneva 4Switzerland
| | - Stefania Vossio
- Department of BiochemistryUniversity of GenevaGeneva 4Switzerland
| | - Cameron Scott
- Department of BiochemistryUniversity of GenevaGeneva 4Switzerland
| | | | | | - Charles Ferguson
- Institute for Molecular Bioscience and Center for Microscopy and MicroanalysisUniversity of QueenslandBrisbaneQldAustralia
| | - Markus Damme
- Biochemisches InstitutChristian‐Albrechts‐UniversitätKielGermany
| | - Marc Moniatte
- Mass Spectrometry Core FacilityEPFLLausanneSwitzerland
| | - Robert G Parton
- Institute for Molecular Bioscience and Center for Microscopy and MicroanalysisUniversity of QueenslandBrisbaneQldAustralia
| | | | - Jean Gruenberg
- Department of BiochemistryUniversity of GenevaGeneva 4Switzerland
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55
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Berselli GB, Sarangi NK, Ramadurai S, Murphy PV, Keyes TE. Microcavity-Supported Lipid Membranes: Versatile Platforms for Building Asymmetric Lipid Bilayers and for Protein Recognition. ACS APPLIED BIO MATERIALS 2019; 2:3404-3417. [DOI: 10.1021/acsabm.9b00378] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Guilherme B. Berselli
- School of Chemical Sciences and National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland
| | - Nirod Kumar Sarangi
- School of Chemical Sciences and National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland
| | - Sivaramakrishnan Ramadurai
- School of Chemical Sciences and National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland
| | - Paul V. Murphy
- School of Chemistry, NUI Galway, University Road, Galway, Ireland
| | - Tia E. Keyes
- School of Chemical Sciences and National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland
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56
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Allender DW, Sodt AJ, Schick M. Cholesterol-Dependent Bending Energy Is Important in Cholesterol Distribution of the Plasma Membrane. Biophys J 2019; 116:2356-2366. [PMID: 31023537 PMCID: PMC6589153 DOI: 10.1016/j.bpj.2019.03.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 02/19/2019] [Accepted: 03/21/2019] [Indexed: 11/16/2022] Open
Abstract
We consider the plasma membrane that contains a cholesterol molar fraction of 0.4 and ask how that cholesterol is distributed between the two leaves. Because of the rapid flip-flop of cholesterol between leaves, we assume that its distribution is determined by the equality of its chemical potentials in the two leaves. When we consider only the contributions of entropy and interactions to the cholesterol chemical potential in our model system, we find, not surprisingly, that the cholesterol is mostly in the outer leaf because of the strong attraction between cholesterol and sphingomyelin (SM), which is predominantly in that leaf. We find 72% there. We then include the contribution from the bending energy in each leaf that must be overcome to join the leaves in a flat bilayer. The product of bending modulus and spontaneous curvature is obtained from simulation. We find that the addition of cholesterol to the outer leaf reduces the spontaneous curvature, which is initially positive, until it passes through zero when the molar fraction of cholesterol in the outer leaf is 0.28. Additional cholesterol is driven toward the inner leaf by the sphingomyelin phosphatidylcholine mixture. This is resisted by the bending energy contribution to the inner leaf. We find, again by simulation, that the addition of cholesterol monotonically increases the magnitude of the spontaneous curvature of the inner leaf, which is negative. This increases its bending energy. We conclude that, as a result of these competing effects, the percentage of cholesterol in the outer leaf is reduced to ∼63 ± 6%.
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Affiliation(s)
- D W Allender
- Department of Physics, University of Washington, Seattle, Washington; Department of Physics, Kent State University, Kent, Ohio
| | - A J Sodt
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Rockville, Maryland
| | - M Schick
- Department of Physics, University of Washington, Seattle, Washington.
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57
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Manna M, Nieminen T, Vattulainen I. Understanding the Role of Lipids in Signaling Through Atomistic and Multiscale Simulations of Cell Membranes. Annu Rev Biophys 2019; 48:421-439. [DOI: 10.1146/annurev-biophys-052118-115553] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cell signaling controls essentially all cellular processes. While it is often assumed that proteins are the key architects coordinating cell signaling, recent studies have shown more and more clearly that lipids are also involved in signaling processes in a number of ways. Lipids do, for instance, act as messengers, modulate membrane receptor conformation and dynamics, and control membrane receptor partitioning. Further, through structural modifications such as oxidation, the functions of lipids as part of signaling processes can be modified. In this context, in this article we discuss the understanding recently revealed by atomistic and coarse-grained computer simulations of nanoscale processes and underlying physicochemical principles related to lipids’ functions in cellular signaling.
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Affiliation(s)
- Moutusi Manna
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, Madhya Pradesh 462 066, India
| | - Tuomo Nieminen
- Computational Physics Laboratory, Tampere University, FI-33014 Tampere, Finland
| | - Ilpo Vattulainen
- Computational Physics Laboratory, Tampere University, FI-33014 Tampere, Finland
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
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58
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Nintemann SJ, Palmgren M, López-Marqués RL. Catch You on the Flip Side: A Critical Review of Flippase Mutant Phenotypes. TRENDS IN PLANT SCIENCE 2019; 24:468-478. [PMID: 30885637 DOI: 10.1016/j.tplants.2019.02.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 01/24/2019] [Accepted: 02/04/2019] [Indexed: 05/05/2023]
Abstract
Lipid flippases are integral membrane proteins that use ATP hydrolysis to power the generation of phospholipid asymmetry between the two leaflets of biological membranes, a process essential for cell survival. Although the first report of a plant lipid flippase was published in 2000, progress in the field has been slow, partially due to the high level of redundancy in this gene family. However, recently an increasing number of reports have examined the physiological function of lipid flippases, mainly in Arabidopsis thaliana. In this review we aim to summarize recent findings on the physiological relevance of lipid flippases in plant adaptation to a changing environment and caution against misinterpretation of pleiotropic effects in genetic studies of flippases.
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Affiliation(s)
- Sebastian J Nintemann
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Michael Palmgren
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Rosa Laura López-Marqués
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark; https://plen.ku.dk/english/research/transport_biology/blf/.
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59
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Rivel T, Ramseyer C, Yesylevskyy S. The asymmetry of plasma membranes and their cholesterol content influence the uptake of cisplatin. Sci Rep 2019; 9:5627. [PMID: 30948733 PMCID: PMC6449338 DOI: 10.1038/s41598-019-41903-w] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 03/18/2019] [Indexed: 12/20/2022] Open
Abstract
The composition of the plasma membrane of malignant cells is thought to influence the cellular uptake of cisplatin and to take part in developing resistance to this widespread anti-cancer drug. In this work we study the permeation of cisplatin through the model membranes of normal and cancer cells using molecular dynamics simulations. A special attention is paid to lipid asymmetry and cholesterol content of the membranes. The loss of lipid asymmetry, which is common for cancer cells, leads to a decrease in their permeability to cisplatin by one order of magnitude in comparison to the membranes of normal cells. The change in the cholesterol molar ratio from 0% to 33% also decreases the permeability of the membrane by approximately one order of magnitude. The permeability of pure DOPC membrane is 5-6 orders of magnitude higher than one of the membranes with realistic lipid composition, which makes it as an inadequate model for the studies of drug permeability.
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Affiliation(s)
- Timothée Rivel
- Laboratoire Chrono Environnement UMR CNRS 6249, Université de Bourgogne Franche-Comté, 16 route de Gray, 25030, Besançon, Cedex, France.
| | - Christophe Ramseyer
- Laboratoire Chrono Environnement UMR CNRS 6249, Université de Bourgogne Franche-Comté, 16 route de Gray, 25030, Besançon, Cedex, France
| | - Semen Yesylevskyy
- Laboratoire Chrono Environnement UMR CNRS 6249, Université de Bourgogne Franche-Comté, 16 route de Gray, 25030, Besançon, Cedex, France.,Department of Physics of Biological Systems, Institute of Physics of the National Academy of Sciences of Ukraine, Prospect Nauky 46, 03028, Kyiv, Ukraine
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60
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Han TW, Ye W, Bethel NP, Zubia M, Kim A, Li KH, Burlingame AL, Grabe M, Jan YN, Jan LY. Chemically induced vesiculation as a platform for studying TMEM16F activity. Proc Natl Acad Sci U S A 2019; 116:1309-1318. [PMID: 30622179 PMCID: PMC6347726 DOI: 10.1073/pnas.1817498116] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Calcium-activated phospholipid scramblase mediates the energy-independent bidirectional translocation of lipids across the bilayer, leading to transient or, in the case of apoptotic scrambling, sustained collapse of membrane asymmetry. Cells lacking TMEM16F-dependent lipid scrambling activity are deficient in generation of extracellular vesicles (EVs) that shed from the plasma membrane in a Ca2+-dependent manner, namely microvesicles. We have adapted chemical induction of giant plasma membrane vesicles (GPMVs), which require both TMEM16F-dependent phospholipid scrambling and calcium influx, as a kinetic assay to investigate the mechanism of TMEM16F activity. Using the GPMV assay, we identify and characterize both inactivating and activating mutants that elucidate the mechanism for TMEM16F activation and facilitate further investigation of TMEM16F-mediated lipid translocation and its role in extracellular vesiculation.
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Affiliation(s)
- Tina W Han
- Howard Hughes Medical Institute, University of California, San Francisco, CA 94143
- Department of Physiology, University of California, San Francisco, CA 94143
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143
| | - Wenlei Ye
- Howard Hughes Medical Institute, University of California, San Francisco, CA 94143
- Department of Physiology, University of California, San Francisco, CA 94143
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143
| | - Neville P Bethel
- Department of Pharmaceutical Chemistry, Cardiovascular Research Institute, University of California, San Francisco, CA 94143
| | - Mario Zubia
- Howard Hughes Medical Institute, University of California, San Francisco, CA 94143
- Department of Physiology, University of California, San Francisco, CA 94143
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143
| | - Andrew Kim
- Howard Hughes Medical Institute, University of California, San Francisco, CA 94143
- Department of Physiology, University of California, San Francisco, CA 94143
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143
| | - Kathy H Li
- Mass Spectrometry Facility, University of California, San Francisco, CA 94143
| | - Alma L Burlingame
- Mass Spectrometry Facility, University of California, San Francisco, CA 94143
| | - Michael Grabe
- Department of Pharmaceutical Chemistry, Cardiovascular Research Institute, University of California, San Francisco, CA 94143
| | - Yuh Nung Jan
- Howard Hughes Medical Institute, University of California, San Francisco, CA 94143
- Department of Physiology, University of California, San Francisco, CA 94143
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143
| | - Lily Y Jan
- Howard Hughes Medical Institute, University of California, San Francisco, CA 94143;
- Department of Physiology, University of California, San Francisco, CA 94143
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143
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61
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Electrophysiological interrogation of asymmetric droplet interface bilayers reveals surface-bound alamethicin induces lipid flip-flop. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:335-343. [DOI: 10.1016/j.bbamem.2018.07.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 07/06/2018] [Accepted: 07/09/2018] [Indexed: 01/16/2023]
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62
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Brown HE, Esher SK, Alspaugh JA. Chitin: A "Hidden Figure" in the Fungal Cell Wall. Curr Top Microbiol Immunol 2019; 425:83-111. [PMID: 31807896 DOI: 10.1007/82_2019_184] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Chitin and chitosan are two related polysaccharides that provide important structural stability to fungal cell walls. Often embedded deeply within the cell wall structure, these molecules anchor other components at the cell surface. Chitin-directed organization of the cell wall layers allows the fungal cell to effectively monitor and interact with the external environment. For fungal pathogens, this interaction includes maintaining cellular strategies to avoid excessive detection by the host innate immune system. In turn, mammalian and plant hosts have developed their own strategies to process fungal chitin, resulting in chitin fragments of varying molecular size. The size-dependent differences in the immune activation behaviors of variably sized chitin molecules help to explain how chitin and related chitooligomers can both inhibit and activate host immunity. Moreover, chitin and chitosan have recently been exploited for many biomedical applications, including targeted drug delivery and vaccine development.
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Affiliation(s)
- Hannah E Brown
- Department of Medicine, Department of Molecular Genetics and Microbiology, Duke University School of Medicine, 303 Sands Research Building, DUMC, 102359, Durham, 27710, NC, USA
| | - Shannon K Esher
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA, USA
| | - J Andrew Alspaugh
- Department of Medicine, Department of Molecular Genetics and Microbiology, Duke University School of Medicine, 303 Sands Research Building, DUMC, 102359, Durham, 27710, NC, USA.
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63
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Johnson SE, Ugolkov A, Haney CR, Bondarenko G, Li L, Waters EA, Bergan R, Tran A, O'Halloran TV, Mazar A, Zhao M. Whole-body Imaging of Cell Death Provides a Systemic, Minimally Invasive, Dynamic, and Near-real Time Indicator for Chemotherapeutic Drug Toxicity. Clin Cancer Res 2018; 25:1331-1342. [PMID: 30420445 DOI: 10.1158/1078-0432.ccr-18-1846] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 10/09/2018] [Accepted: 11/07/2018] [Indexed: 12/31/2022]
Abstract
PURPOSE Response to toxicity in chemotherapies varies considerably from tissue to tissue and from patient to patient. An ability to monitor the tissue damage done by chemotherapy may have a profound impact on treatment and prognosis allowing for a proactive management in understanding and mitigating such events. For the first time, we investigated the feasibility of using whole-body imaging to map chemotherapeutic drug-induced toxicity on an individual basis. EXPERIMENTAL DESIGN In a preclinical proof-of-concept, rats were treated with a single clinical dose of cyclophosphamide, methotrexate, or cisplatin. In vivo whole-body imaging data were acquired using 99mTc-duramycin, which identifies dead and dying cells as an unambiguous marker for tissue injury in susceptible organs. Imaging results were cross-validated using quantitative ex vivo measurements and histopathology and compared with standard blood and serum panels for toxicology. RESULTS The in vivo whole-body imaging data detected widespread changes, where spatially heterogeneous toxic effects were identified across different tissues, within substructures of organs, as well as among different individuals. The signal changes were consistent with established toxicity profiles of these chemotherapeutic drugs. Apart from generating a map of susceptible tissues, this in vivo imaging approach was more sensitive compared with conventional blood and serum markers used in toxicology. Also, repeated imaging during the acute period after drug treatment captured different kinetics of tissue injury among susceptible organs in males and females. CONCLUSIONS This novel and highly translational imaging approach shows promise in optimizing therapeutic decisions by detecting and managing drug toxicity on a personalized basis.Toxicity to normal tissues is a significant limitation in chemotherapies. This work demonstrated an in vivo imaging-based approach for characterizing toxicity-induced tissue injury in a systemic, dynamic, and near-real time fashion. This novel approach shows promise in optimizing therapeutic decisions by monitoring drug toxicity on a personalized basis.
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Affiliation(s)
- Steven E Johnson
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Andrey Ugolkov
- Division of Hematology/Oncology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.,Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois
| | - Chad R Haney
- Center for Advanced Molecular Imaging, Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois
| | - Gennadiy Bondarenko
- Division of Hematology/Oncology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.,Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois
| | - Lin Li
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Emily A Waters
- Center for Advanced Molecular Imaging, Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois
| | - Raymond Bergan
- Division of Hematology/Oncology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Andy Tran
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Thomas V O'Halloran
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois.,Department of Chemistry, Northwestern University, Evanston, Illinois
| | - Andrew Mazar
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois. .,Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Ming Zhao
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois. .,Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois
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64
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Drechsler C, Markones M, Choi JY, Frieling N, Fiedler S, Voelker DR, Schubert R, Heerklotz H. Preparation of Asymmetric Liposomes Using a Phosphatidylserine Decarboxylase. Biophys J 2018; 115:1509-1517. [PMID: 30266319 DOI: 10.1016/j.bpj.2018.08.036] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 08/18/2018] [Accepted: 08/21/2018] [Indexed: 01/08/2023] Open
Abstract
Lipid asymmetries between the outer and inner leaflet of the lipid bilayer exist in nearly all biological membranes. Although living cells spend great effort to adjust and maintain these asymmetries, little is known about the biophysical phenomena within asymmetric membranes and their role in cellular function. One reason for this lack of insight into such a fundamental membrane property is the fact that the majority of model-membrane studies have been performed on symmetric membranes. Our aim is to overcome this problem by employing a targeted, enzymatic reaction to prepare asymmetric liposomes with phosphatidylserine (PS) primarily in the inner leaflet. To achieve this goal, we use a recombinant version of a water soluble PS decarboxylase from Plasmodium knowlesi, which selectively decarboxylates PS in the outer leaflet, converting it to phosphatidylethanolamine. The extent of decarboxylation is quantified using high-performance thin-layer chromatography, and the local concentration of anionic PS in the outer leaflet is monitored in terms of the ζ potential. Starting, for example, with 21 mol % 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine sodium salt, the assay leads to liposomes with 21 mol % in the inner and 6 mol % PS in the outer leaflet. This asymmetry persists virtually unchanged for at least 4 days at 20°C and at least 2 days at 40°C. The use of a highly specific enzyme carries the advantage that a minor component such as PS can be adjusted without affecting or being affected by the other lipid species present in the model membrane. The phenomena governing the residual outside PS content are addressed but warrant further study.
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Affiliation(s)
- Carina Drechsler
- Institute for Pharmaceutical Sciences, University of Freiburg, Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Freiburg, Germany
| | - Marie Markones
- Institute for Pharmaceutical Sciences, University of Freiburg, Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Freiburg, Germany
| | - Jae-Yeon Choi
- Department of Medicine, National Jewish Health, Denver, Colorado
| | - Niklas Frieling
- Institute for Pharmaceutical Sciences, University of Freiburg, Freiburg, Germany
| | - Sebastian Fiedler
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Dennis R Voelker
- Department of Medicine, National Jewish Health, Denver, Colorado
| | - Rolf Schubert
- Institute for Pharmaceutical Sciences, University of Freiburg, Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Freiburg, Germany
| | - Heiko Heerklotz
- Institute for Pharmaceutical Sciences, University of Freiburg, Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Freiburg, Germany; Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada.
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65
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Grassi S, Chiricozzi E, Mauri L, Sonnino S, Prinetti A. Sphingolipids and neuronal degeneration in lysosomal storage disorders. J Neurochem 2018; 148:600-611. [PMID: 29959861 DOI: 10.1111/jnc.14540] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 06/25/2018] [Accepted: 06/27/2018] [Indexed: 12/27/2022]
Abstract
Ceramide, sphingomyelin, and glycosphingolipids (both neutral and acidic) are characterized by the presence in the lipid moiety of an aliphatic base known as sphingosine. Altogether, they are called sphingolipids and are particularly abundant in neuronal plasma membranes, where, via interactions with the other membrane lipids and membrane proteins, they play a specific role in modulating the cell signaling processes. The metabolic pathways determining the plasma membrane sphingolipid composition are thus the key point for functional changes of the cell properties. Unnatural changes of the neuronal properties are observed in sphingolipidoses, lysosomal storage diseases occurring when a lysosomal sphingolipid hydrolase is not working, leading to the accumulation of the substrate and to its distribution to all the cell membranes interacting with lysosomes. Moreover, secondary accumulation of sphingolipids is a common trait of other lysosomal storage diseases. This article is part of the Special Issue "Lysosomal Storage Disorders".
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Affiliation(s)
- Sara Grassi
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Elena Chiricozzi
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Laura Mauri
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Sandro Sonnino
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Alessandro Prinetti
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
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66
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Brown HE, Ost KS, Esher SK, Pianalto KM, Saelens JW, Guan Z, Andrew Alspaugh J. Identifying a novel connection between the fungal plasma membrane and pH-sensing. Mol Microbiol 2018; 109:474-493. [PMID: 29885030 PMCID: PMC6173979 DOI: 10.1111/mmi.13998] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/27/2018] [Indexed: 01/11/2023]
Abstract
The mechanisms by which micro-organisms sense and internalize extracellular pH signals are not completely understood. One example of a known external pH-sensing process is the fungal-specific Rim/Pal signal transduction pathway. Fungi, such as the opportunistic pathogen Cryptococcus neoformans, use Rim signaling to sense and respond to changes in environmental pH. Mutations in this pathway result in strains that are attenuated for survival at alkaline pH, and often for survival within the host. Here, we used an insertional mutagenesis screen to identify novel genes required for C. neoformans growth at host pH. We discovered altered alkaline pH growth in several strains with specific defects in plasma membrane composition and maintenance of phospholipid assembly. Among these, loss of function of the Cdc50 lipid flippase regulatory subunit affected the temporal dynamics of Rim pathway activation. We defined distinct and overlapping cellular processes regulated by Rim101 and Cdc50 through analysis of the transcriptome in these mutant strains. We further explored how pH-induced membrane changes affect membrane-bound pH-sensing proteins, specifically the C-terminal domain of the Rra1 protein, an upstream Rim pathway activator and pH sensor. These results suggest both broadly applicable and phylum-specific molecular interactions that drive microbial environmental sensing.
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Affiliation(s)
- Hannah E Brown
- Departments of Molecular Genetics and Microbiology/Medicine, Duke University School of Medicine, Durham, NC, USA
| | - Kyla S Ost
- Departments of Molecular Genetics and Microbiology/Medicine, Duke University School of Medicine, Durham, NC, USA
| | - Shannon K Esher
- Departments of Molecular Genetics and Microbiology/Medicine, Duke University School of Medicine, Durham, NC, USA
| | - Kaila M Pianalto
- Departments of Molecular Genetics and Microbiology/Medicine, Duke University School of Medicine, Durham, NC, USA
| | - Joseph W Saelens
- Departments of Molecular Genetics and Microbiology/Medicine, Duke University School of Medicine, Durham, NC, USA
| | - Ziqiang Guan
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - J Andrew Alspaugh
- Departments of Molecular Genetics and Microbiology/Medicine, Duke University School of Medicine, Durham, NC, USA
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67
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Peyret A, Zhao H, Lecommandoux S. Preparation and Properties of Asymmetric Synthetic Membranes Based on Lipid and Polymer Self-Assembly. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:3376-3385. [PMID: 29486556 DOI: 10.1021/acs.langmuir.7b04233] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Cell membrane asymmetry is a common structural feature of all biological cells. Researchers have tried for decades to better study its formation and its function in membrane-regulated phenomena. In particular, there has been increasing interest in developing synthetic asymmetric membrane models in the laboratory, with the aim of studying basic physical chemistry properties that may be correlated to a relevant biological function. The present article aims to summarize the main presented approaches to prepare asymmetric membranes, which are most often made from lipids, polymers, or a combination of both.
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Affiliation(s)
- Ariane Peyret
- Laboratoire de Chimie des Polymères Organiques, LCPO, Université de Bordeaux, CNRS, Bordeaux INP, UMR 5629 , 16 Avenue Pey Berland F-33600 Pessac , France
| | - Hang Zhao
- Laboratoire de Chimie des Polymères Organiques, LCPO, Université de Bordeaux, CNRS, Bordeaux INP, UMR 5629 , 16 Avenue Pey Berland F-33600 Pessac , France
| | - Sébastien Lecommandoux
- Laboratoire de Chimie des Polymères Organiques, LCPO, Université de Bordeaux, CNRS, Bordeaux INP, UMR 5629 , 16 Avenue Pey Berland F-33600 Pessac , France
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68
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Rosilio V. How Can Artificial Lipid Models Mimic the Complexity of Molecule–Membrane Interactions? ACTA ACUST UNITED AC 2018. [DOI: 10.1016/bs.abl.2017.12.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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69
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Coreta-Gomes FM, Vaz WLC, Moreno MJ. Effect of Acyl Chain Length on the Rate of Phospholipid Flip-Flop and Intermembrane Transfer. J Membr Biol 2017; 251:431-442. [PMID: 29264685 DOI: 10.1007/s00232-017-0009-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 12/13/2017] [Indexed: 11/25/2022]
Abstract
The rate at which phospholipids equilibrate between different membranes and between the non-polar environments in biological fluids is of high importance in the understanding of biomembrane diversity, as well as in the development of liposomes for drug delivery. In this work, we characterize the rate of insertion into and desorption from POPC bilayers for a homologous series of amphiphiles with the fluorescent NBD group attached to phosphoethanolamines of different acyl chain lengths, NBD-diC n -PE with n = 6, 8, 10, and 12. The rate of translocation between bilayer leaflets was also characterized, providing all the relevant parameters for their interaction with lipid bilayers. The results are complemented with data for NBD-diC14-PE obtained from literature (Abreu et al. Biophys J 87:353-365, 2004; Moreno et al. Biophys J 91:873-881, 2006). The rate of translocation between the POPC leaflets is not dependent on the length of the acyl chains, while this affects strongly the rate of desorption from the bilayer. Insertion in the POPC bilayer is not diffusion controlled showing a significant dependence on the acyl chain length and on temperature. The results obtained are compared with those previously reported for NBD-LysoC14-PE (Sampaio et al. Biophys J 88:4064-4071, 2005), and with the homologous series of single chain amphiphiles NBD-C n (Cardoso et al. J Phys Chem B 114:16337-16346, 2010; J Phys Chem B 115:10098-10108, 2011). This allows the establishment of important relations between the rate constants for interaction with the lipid bilayers and the structural properties of the amphiphiles, namely the total surface and the cross-section of their non-polar region.
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Affiliation(s)
- Filipe M Coreta-Gomes
- CQC-Biological Chemistry Group, Chemistry Department FCTUC, Largo D. Dinis, Rua Larga, 3004-535, Coimbra, Portugal
- QOPNA, Chemistry Department, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Winchil L C Vaz
- CEDOC, NOVA Medical School, Faculdadede Ciências Médicas, Universidade NOVA de Lisboa, 1169-056, Lisbon, Portugal
| | - Maria J Moreno
- CQC-Biological Chemistry Group, Chemistry Department FCTUC, Largo D. Dinis, Rua Larga, 3004-535, Coimbra, Portugal.
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70
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ω-3 Long Chain Polyunsaturated Fatty Acids as Sensitizing Agents and Multidrug Resistance Revertants in Cancer Therapy. Int J Mol Sci 2017; 18:ijms18122770. [PMID: 29261109 PMCID: PMC5751368 DOI: 10.3390/ijms18122770] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/23/2017] [Accepted: 12/16/2017] [Indexed: 12/11/2022] Open
Abstract
Chemotherapy efficacy is strictly limited by the resistance of cancer cells. The ω-3 long chain polyunsaturated fatty acids (ω-3 LCPUFAs) are considered chemosensitizing agents and revertants of multidrug resistance by pleiotropic, but not still well elucidated, mechanisms. Nowadays, it is accepted that alteration in gene expression, modulation of cellular proliferation and differentiation, induction of apoptosis, generation of reactive oxygen species, and lipid peroxidation are involved in ω-3 LCPUFA chemosensitizing effects. A crucial mechanism in the control of cell drug uptake and efflux is related to ω-3 LCPUFA influence on membrane lipid composition. The incorporation of docosahexaenoic acid in the lipid rafts produces significant changes in their physical-chemical properties affecting content and functions of transmembrane proteins, such as growth factors, receptors and ATP-binding cassette transporters. Of note, ω-3 LCPUFAs often alter the lipid compositions more in chemoresistant cells than in chemosensitive cells, suggesting a potential adjuvant role in the treatment of drug resistant cancers.
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71
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Spassieva S, Bieberich E. Lysosphingolipids and sphingolipidoses: Psychosine in Krabbe's disease. J Neurosci Res 2017; 94:974-81. [PMID: 27638582 DOI: 10.1002/jnr.23888] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 07/24/2016] [Accepted: 07/25/2016] [Indexed: 12/14/2022]
Abstract
Until recently, lipids were considered inert building blocks of cellular membranes. This changed three decades ago when lipids were found to regulate cell polarity and vesicle transport, and the "lipid raft" concept took shape. The lipid-driven membrane anisotropy in form of "rafts" that associate with proteins led to the view that organized complexes of lipids and proteins regulate various cell functions. Disturbance of this organization can lead to cellular, tissue, and organ malfunction. Sphingolipidoses, lysosomal storage diseases that are caused by enzyme deficiencies in the sphingolipid degradation pathway, were found to be particularly detrimental to the brain. These enzyme deficiencies result in accumulation of sphingolipid metabolites in lysosomes, although it is not yet clear how this accumulation affects the organization of lipids in cellular membranes. Krabbe's disease (KD), or globoid cell leukodystrophy, was one of the first sphingolipidosis for which the raft concept offered a potential mechanism. KD is caused by mutations in the enzyme β-galactocerebrosidase; however, elevation of its substrate, galactosylceramide, is not observed or considered detrimental. Instead, it was found that a byproduct of galactosylceramide metabolism, the lysosphingolipid psychosine, is accumulated. The "psychosine hypothesis" has been refined by showing that psychosine disrupts lipid rafts and vesicular transport critical for the function of glia and neurons. The role of psychosine in KD is an example of how the disruption of sphingolipid metabolism can lead to elevation of a toxic lysosphingolipid, resulting in disruption of cellular membrane organization and neurotoxicity. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Stefka Spassieva
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, Texas
| | - Erhard Bieberich
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Geogia.
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72
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Hirama T, Lu SM, Kay JG, Maekawa M, Kozlov MM, Grinstein S, Fairn GD. Membrane curvature induced by proximity of anionic phospholipids can initiate endocytosis. Nat Commun 2017; 8:1393. [PMID: 29123120 PMCID: PMC5680216 DOI: 10.1038/s41467-017-01554-9] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Accepted: 09/27/2017] [Indexed: 11/09/2022] Open
Abstract
The plasma membrane is uniquely enriched in phosphatidylserine (PtdSer). This anionic phospholipid is restricted almost exclusively to the inner leaflet of the plasmalemma. Because of their high density, the headgroups of anionic lipids experience electrostatic repulsion that, being exerted asymmetrically, is predicted to favor membrane curvature. We demonstrate that cholesterol limits this repulsion and tendency to curve. Removal of cholesterol or insertion of excess PtdSer increases the charge density of the inner leaflet, generating foci of enhanced charge and curvature where endophilin and synaptojanin are recruited. From these sites emerge tubules that undergo fragmentation, resulting in marked endocytosis of PtdSer. Shielding or reduction of the surface charge or imposition of outward membrane tension minimized invagination and PtdSer endocytosis. We propose that cholesterol associates with PtdSer to form nanodomains where the headgroups of PtdSer are maintained sufficiently separated to limit spontaneous curvature while sheltering the hydrophobic sterol from the aqueous medium.
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Affiliation(s)
- Takashi Hirama
- Program in Cell Biology, The Hospital for Sick Children, 555 University Avenue, Toronto, ON, Canada, M5G 1X8.,Department of Respiratory Medicine, Saitama Medical University, Moroyama, Saitama, 3500495, Japan.,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, 209 Victoria Street, Toronto, ON, Canada, M5B 1T8
| | - Stella M Lu
- Program in Cell Biology, The Hospital for Sick Children, 555 University Avenue, Toronto, ON, Canada, M5G 1X8.,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, 209 Victoria Street, Toronto, ON, Canada, M5B 1T8.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada, M5S 1A8
| | - Jason G Kay
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, NY, 14214, USA
| | - Masashi Maekawa
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, 209 Victoria Street, Toronto, ON, Canada, M5B 1T8.,Department of Biochemistry and Molecular Genetics, Ehime University Graduate School of Medicine; Division of Cell Growth and Tumour Regulation, Proteo-Science Center, Ehime University, Toon, Ehime, 7910295, Japan
| | - Michael M Kozlov
- Department of Physiology and Pharmacology, Room 546, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Sergio Grinstein
- Program in Cell Biology, The Hospital for Sick Children, 555 University Avenue, Toronto, ON, Canada, M5G 1X8.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada, M5S 1A8.,Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8
| | - Gregory D Fairn
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, 209 Victoria Street, Toronto, ON, Canada, M5B 1T8. .,Department of Biochemistry, University of Toronto, Toronto, ON, Canada, M5S 1A8. .,Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8. .,Department of Surgery, University of Toronto, Toronto, ON, Canada, M5T 1P5.
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73
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Structural basis of MsbA-mediated lipopolysaccharide transport. Nature 2017; 549:233-237. [PMID: 28869968 DOI: 10.1038/nature23649] [Citation(s) in RCA: 183] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Accepted: 07/12/2017] [Indexed: 12/20/2022]
Abstract
Lipopolysaccharide (LPS) in the outer membrane of Gram-negative bacteria is critical for the assembly of their cell envelopes. LPS synthesized in the cytoplasmic leaflet of the inner membrane is flipped to the periplasmic leaflet by MsbA, an ATP-binding cassette transporter. Despite substantial efforts, the structural mechanisms underlying MsbA-driven LPS flipping remain elusive. Here we use single-particle cryo-electron microscopy to elucidate the structures of lipid-nanodisc-embedded MsbA in three functional states. The 4.2 Å-resolution structure of the transmembrane domains of nucleotide-free MsbA reveals that LPS binds deep inside MsbA at the height of the periplasmic leaflet, establishing extensive hydrophilic and hydrophobic interactions with MsbA. Two sub-nanometre-resolution structures of MsbA with ADP-vanadate and ADP reveal an unprecedented closed and an inward-facing conformation, respectively. Our study uncovers the structural basis for LPS recognition, delineates the conformational transitions of MsbA to flip LPS, and paves the way for structural characterization of other lipid flippases.
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74
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Ng WP, Webster KD, Stefani C, Schmid EM, Lemichez E, Bassereau P, Fletcher DA. Force-induced transcellular tunnel formation in endothelial cells. Mol Biol Cell 2017; 28:mbc.E17-01-0080. [PMID: 28794268 PMCID: PMC5620373 DOI: 10.1091/mbc.e17-01-0080] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 06/21/2017] [Accepted: 08/04/2017] [Indexed: 01/13/2023] Open
Abstract
The endothelium serves as a protective semipermeable barrier in blood vessels and lymphatic vessels. Leukocytes and pathogens can pass directly through the endothelium by opening holes in endothelial cells, known as transcellular tunnels, which are formed by contact and self-fusion of the apical and basal plasma membranes. Here we test the hypothesis that the actin cytoskeleton is the primary barrier to transcellular tunnel formation using a combination of atomic force microscopy and fluorescence microscopy of live cells. We find that localized mechanical forces are sufficient to induce the formation of transcellular tunnels in HUVECs. When HUVECs are exposed to the bacterial toxin EDIN, which can induce spontaneous transcellular tunnels, less mechanical work is required to form tunnels due to the reduced cytoskeletal stiffness and thickness of these cells, similar to the effects of a ROCK inhibitor. We also observe actin enrichment in response to mechanical indentation that is reduced in cells exposed to the bacterial toxin. Our study shows that the actin cytoskeleton of endothelial cells provides both passive and active resistance against transcellular tunnel formation, serving as a mechanical barrier that can be overcome by mechanical force as well as disruption of the cytoskeleton.
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Affiliation(s)
- Win Pin Ng
- UC Berkeley/UC San Francisco Graduate Group in Bioengineering, Berkeley, California 94720
- Department of Bioengineering, University of California, Berkeley, California 94720
| | - Kevin D Webster
- Department of Bioengineering, University of California, Berkeley, California 94720
- Biophysics Graduate Group, University of California, Berkeley, California 94720
| | - Caroline Stefani
- INSERM, U1065, Université de Nice-Sophie-Antipolis, Centre Méditerranéen de Médecine Moléculaire, C3M, Nice 06204, France
| | - Eva M Schmid
- Department of Bioengineering, University of California, Berkeley, California 94720
| | - Emmanuel Lemichez
- INSERM, U1065, Université de Nice-Sophie-Antipolis, Centre Méditerranéen de Médecine Moléculaire, C3M, Nice 06204, France
| | - Patricia Bassereau
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, 75005, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, 75005, Paris, France
| | - Daniel A Fletcher
- UC Berkeley/UC San Francisco Graduate Group in Bioengineering, Berkeley, California 94720
- Department of Bioengineering, University of California, Berkeley, California 94720
- Biophysics Graduate Group, University of California, Berkeley, California 94720
- Biological Systems & Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
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75
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Lemke G. Phosphatidylserine Is the Signal for TAM Receptors and Their Ligands. Trends Biochem Sci 2017; 42:738-748. [PMID: 28734578 DOI: 10.1016/j.tibs.2017.06.004] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 06/04/2017] [Accepted: 06/08/2017] [Indexed: 12/20/2022]
Abstract
Nature repeatedly repurposes, in that molecules that serve as metabolites, energy depots, or polymer subunits are at the same time used to deliver signals within and between cells. The preeminent example of this repurposing is ATP, which functions as a building block for nucleic acids, an energy source for enzymatic reactions, a phosphate donor to regulate intracellular signaling, and a neurotransmitter to control the activity of neurons. A series of recent studies now consolidates the view that phosphatidylserine (PtdSer), a common phospholipid constituent of membrane bilayers, is similarly repurposed for use as a signal between cells and that the ligands and receptors of the Tyro3/Axl/Mer (TAM) family of receptor tyrosine kinases (RTKs) are prominent transducers of this signal.
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Affiliation(s)
- Greg Lemke
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA; Immunobiology and Microbial Pathogenesis Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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76
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Escribá PV. Membrane-lipid therapy: A historical perspective of membrane-targeted therapies - From lipid bilayer structure to the pathophysiological regulation of cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1493-1506. [PMID: 28577973 DOI: 10.1016/j.bbamem.2017.05.017] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Our current understanding of membrane lipid composition, structure and functions has led to the investigation of their role in cell signaling, both in healthy and pathological cells. As a consequence, therapies based on the regulation of membrane lipid composition and structure have been recently developed. This novel field, known as Membrane Lipid Therapy, is growing and evolving rapidly, providing treatments that are now in use or that are being studied for their application to oncological disorders, Alzheimer's disease, spinal cord injury, stroke, diabetes, obesity, and neuropathic pain. This field has arisen from relevant discoveries on the behavior of membranes in recent decades, and it paves the way to adopt new approaches in modern pharmacology and nutrition. This innovative area will promote further investigation into membranes and the development of new therapies with molecules that target the cell membrane. Due to the prominent roles of membranes in the cells' physiology and the paucity of therapeutic approaches based on the regulation of the lipids they contain, it is expected that membrane lipid therapy will provide new treatments for numerous pathologies. The first on-purpose rationally designed molecule in this field, minerval, is currently being tested in clinical trials and it is expected to enter the market around 2020. However, it seems feasible that during the next few decades other membrane regulators will also be marketed for the treatment of human pathologies. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.
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Affiliation(s)
- Pablo V Escribá
- Department of Biology, University of the Balearic Islands, E-07122 Palma de Mallorca, Spain.
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77
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Visser J, van Staden PJ, Soma P, Buys AV, Pretorius E. The stabilizing effect of an oligomeric proanthocyanidin on red blood cell membrane structure of poorly controlled Type II diabetes. Nutr Diabetes 2017; 7:e275. [PMID: 28504711 PMCID: PMC5518807 DOI: 10.1038/nutd.2017.25] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 03/17/2017] [Accepted: 03/24/2017] [Indexed: 02/06/2023] Open
Abstract
Type II diabetes (T2D) is a pandemic characterized by pathological circulating inflammatory markers, high-glucose levels and oxidative stress. The hematological system is especially vulnerable to these aberrant circulating molecules, and erythrocytes (RBCs) show aberrant rheology properties, owing to the direct contact with these molecules. Pathological levels of circulating inflammatory markers in T2D therefore have a direct effect on the molecular and cellular structure of RBCs. Previous research has suggested that antioxidants may reduce oxidative stress that results from the pathological inflammatory markers. Particularly, polyphenol antioxidants like oligomeric proanthocyanidins (OPCs) may act as a hydroxyl mopping agent, and may have a positive effect on the deformability and membrane protein structure of RBCs from T2D. In this paper, we look at the effect of one such agent, Pinus massoniana bark extract (standardized to 95% oligomeric proanthicyanidins), on the RBC membrane structures and RBC shape changes of T2D, after laboratory exposure at physiological levels. Our methods of choice were atomic force microscopy and scanning electron microscopy to study RBC elasticity and ultrastructure. Results showed that in our hands, this OPC could change both the eryptotic nature of the RBCs, as viewed with scanning electron microscopy, as well as the elasticity. We found a significant difference in variation between the elasticity measurement values between the RBCs before and after OPC exposure (P-value <0.0001). In conclusion, the data from both these techniques therefore suggest that OPC usage might contribute to the improvement of RBC functioning.
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Affiliation(s)
- J Visser
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Arcadia, South Africa
| | - P J van Staden
- Department of Statistics, Faculty of Natural and Agricultural Sciences, University of Pretoria, Hatfield, South Africa
| | - P Soma
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Arcadia, South Africa
| | - A V Buys
- Unit for Microscopy and Microanalysis, University of Pretoria, Arcadia, South Africa
| | - E Pretorius
- Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa
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78
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Escribá PV. WITHDRAWN: Membrane-lipid therapy: A historical perspective of membrane-targeted therapies-From lipid bilayer structure to the pathophysiological regulation of cells. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2017:S0005-2736(17)30139-6. [PMID: 28476630 DOI: 10.1016/j.bbamem.2017.04.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 04/23/2017] [Accepted: 04/25/2017] [Indexed: 11/19/2022]
Abstract
The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/10.1016/j.bbamem.2017.05.017. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.
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Affiliation(s)
- Pablo V Escribá
- Department of Biology, University of the Balearic Islands, E-07122 Palma de Mallorca, Spain.
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79
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Vermeulen I, Baird M, Al-Dulayymi J, Smet M, Verschoor J, Grooten J. Mycolates of Mycobacterium tuberculosis modulate the flow of cholesterol for bacillary proliferation in murine macrophages. J Lipid Res 2017; 58:709-718. [PMID: 28193630 DOI: 10.1194/jlr.m073171] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Revised: 01/28/2017] [Indexed: 12/11/2022] Open
Abstract
The differentiation of macrophages into lipid-filled foam cells is a hallmark of the lung granuloma that forms in patients with active tuberculosis (TB). Mycolic acids (MAs), the abundant lipid virulence factors in the cell wall of Mycobacterium tuberculosis (Mtb), can induce this foam phenotype possibly as a way to perturb host cell lipid homeostasis to support the infection. It is not exactly clear how MAs allow differentiation of foam cells during Mtb infection. Here we investigated how chemically synthetic MAs, each with a defined stereochemistry similar to natural Mtb-associated mycolates, influence cell foamy phenotype and mycobacterial proliferation in murine host macrophages. Using light and laser-scanning-confocal microscopy, we assessed the influence of MA structure first on the induction of granuloma cell types, second on intracellular cholesterol accumulation, and finally on mycobacterial growth. While methoxy-MAs (mMAs) effected multi-vacuolar giant cell formation, keto-MAs (kMAs) induced abundant intracellular lipid droplets that were packed with esterified cholesterol. Macrophages from mice treated with kMA were permissive to mycobacterial growth, whereas cells from mMA treatment were not. This suggests a separate yet key involvement of oxygenated MAs in manipulating host cell lipid homeostasis to establish the state of TB.
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Affiliation(s)
- Ilke Vermeulen
- Laboratory of Molecular Immunology, Department of Biomedical Molecular Biology, Ghent University, Ghent Zwijnaarde 9052, Belgium; Department of Biochemistry, University of Pretoria, Pretoria 0002, South Africa
| | - Mark Baird
- School of Chemistry, Bangor University, Bangor LL57 2UW, United Kingdom
| | - Juma Al-Dulayymi
- School of Chemistry, Bangor University, Bangor LL57 2UW, United Kingdom
| | - Muriel Smet
- Laboratory of Molecular Immunology, Department of Biomedical Molecular Biology, Ghent University, Ghent Zwijnaarde 9052, Belgium
| | - Jan Verschoor
- Department of Biochemistry, University of Pretoria, Pretoria 0002, South Africa
| | - Johan Grooten
- Laboratory of Molecular Immunology, Department of Biomedical Molecular Biology, Ghent University, Ghent Zwijnaarde 9052, Belgium.
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80
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Orthogonal lipid sensors identify transbilayer asymmetry of plasma membrane cholesterol. Nat Chem Biol 2016; 13:268-274. [PMID: 28024150 DOI: 10.1038/nchembio.2268] [Citation(s) in RCA: 162] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 10/21/2016] [Indexed: 11/08/2022]
Abstract
Controlled distribution of lipids across various cell membranes is crucial for cell homeostasis and regulation. We developed an imaging method that allows simultaneous in situ quantification of cholesterol in two leaflets of the plasma membrane (PM) using tunable orthogonal cholesterol sensors. Our imaging revealed marked transbilayer asymmetry of PM cholesterol (TAPMC) in various mammalian cells, with the concentration in the inner leaflet (IPM) being ∼12-fold lower than that in the outer leaflet (OPM). The asymmetry was maintained by active transport of cholesterol from IPM to OPM and its chemical retention at OPM. Furthermore, the increase in the IPM cholesterol level was triggered in a stimulus-specific manner, allowing cholesterol to serve as a signaling lipid. We found excellent correlation between the IPM cholesterol level and cellular Wnt signaling activity, suggesting that TAPMC and stimulus-induced PM cholesterol redistribution are crucial for tight regulation of cellular processes under physiological conditions.
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81
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Whitlock JM, Hartzell HC. Anoctamins/TMEM16 Proteins: Chloride Channels Flirting with Lipids and Extracellular Vesicles. Annu Rev Physiol 2016; 79:119-143. [PMID: 27860832 DOI: 10.1146/annurev-physiol-022516-034031] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Anoctamin (ANO)/TMEM16 proteins exhibit diverse functions in cells throughout the body and are implicated in several human diseases. Although the founding members ANO1 (TMEM16A) and ANO2 (TMEM16B) are Ca2+-activated Cl- channels, most ANO paralogs are Ca2+-dependent phospholipid scramblases that serve as channels facilitating the movement (scrambling) of phospholipids between leaflets of the membrane bilayer. Phospholipid scrambling significantly alters the physical properties of the membrane and its landscape and has vast downstream signaling consequences. In particular, phosphatidylserine exposed on the external leaflet of the plasma membrane functions as a ligand for receptors vital for cell-cell communication. A major consequence of Ca2+-dependent scrambling is the release of extracellular vesicles that function as intercellular messengers by delivering signaling proteins and noncoding RNAs to alter target cell function. We discuss the physiological implications of Ca2+-dependent phospholipid scrambling, the extracellular vesicles associated with this activity, and the roles of ANOs in these processes.
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Affiliation(s)
- Jarred M Whitlock
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322;
| | - H Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322;
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82
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Lipidomics-Reshaping the Analysis and Perception of Type 2 Diabetes. Int J Mol Sci 2016; 17:ijms17111841. [PMID: 27827927 PMCID: PMC5133841 DOI: 10.3390/ijms17111841] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 10/28/2016] [Accepted: 10/31/2016] [Indexed: 12/11/2022] Open
Abstract
As a consequence of a sedentary lifestyle as well as changed nutritional behavior, today's societies are challenged by the rapid propagation of metabolic disorders. A common feature of diseases, such as obesity and type 2 diabetes (T2D), is the dysregulation of lipid metabolism. Our understanding of the mechanisms underlying these diseases is hampered by the complexity of lipid metabolic pathways on a cellular level. Furthermore, overall lipid homeostasis in higher eukaryotic organisms needs to be maintained by a highly regulated interplay between tissues, such as adipose tissue, liver and muscle. Unraveling pathological mechanisms underlying metabolic disorders therefore requires a diversified approach, integrating basic cellular research with clinical research, ultimately relying on the analytical power of mass spectrometry-based techniques. Here, we discuss recent progress in the development of lipidomics approaches to resolve the pathological mechanisms of metabolic diseases and to identify suitable biomarkers for clinical application. Due to its growing impact worldwide, we focus on T2D to highlight the key role of lipidomics in our current understanding of this disease, discuss remaining questions and suggest future strategies to address them.
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83
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Lin X, Zhang S, Ding H, Levental I, Gorfe AA. The aliphatic chain of cholesterol modulates bilayer interleaflet coupling and domain registration. FEBS Lett 2016; 590:3368-3374. [PMID: 27590031 DOI: 10.1002/1873-3468.12383] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 08/25/2016] [Accepted: 08/29/2016] [Indexed: 11/10/2022]
Abstract
Cholesterol is a necessary component and critical regulator of liquid-ordered membrane domains. However, the structural features that determine its unique physicochemical behaviors are not fully understood. In particular, very little is known about the specific functions of the terminal aliphatic chain of cholesterol, as previous studies have focused mainly on the rigid sterol ring structure and its hydroxyl head. In the current work, we used coarse-grained molecular dynamics simulations to investigate the effect of cholesterol aliphatic chain length on the dynamics and structure of coexisting lipid domains. We found that the aliphatic chain has no appreciable effect on phase separation per se, but it significantly affects the rate of cholesterol flip-flop and intermonolayer interaction. These effects are accompanied by changes in domain dynamics, lateral pressure, and interleaflet coupling. Our study provides useful insight into how biological sterols modulate communication between the outer and inner surfaces of the plasma membrane and, therefore, cellular signaling.
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Affiliation(s)
- Xubo Lin
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Texas 77030, USA
| | - Siya Zhang
- State Key Laboratory of Medical Molecular Biology, School of Basic Medicine, Peking Union Medical College and Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Beijing 100005, China.,Department of Immunology, The University of Texas MD Anderson Cancer Center, Texas 77054, USA
| | - Hui Ding
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Texas 77030, USA.,Department of Respiratory Medicine, Yixing Hospital affiliated Jiangsu University, Jiangsu 214200, China
| | - Ilya Levental
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Texas 77030, USA
| | - Alemayehu A Gorfe
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Texas 77030, USA
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84
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On the puzzling distribution of cholesterol in the plasma membrane. Chem Phys Lipids 2016; 199:35-38. [DOI: 10.1016/j.chemphyslip.2015.12.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 12/04/2015] [Accepted: 12/09/2015] [Indexed: 01/30/2023]
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85
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Tian J, Nickels J, Katsaras J, Cheng X. Behavior of Bilayer Leaflets in Asymmetric Model Membranes: Atomistic Simulation Studies. J Phys Chem B 2016; 120:8438-48. [DOI: 10.1021/acs.jpcb.6b02148] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - John Katsaras
- The Bredesen Center for Interdisciplinary Research and Graduate Education, 444 Greve Hall, 821 Volunteer Boulevard, Knoxville, Tennessee 37996-3394, United States
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86
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Simons K. Cell membranes: A subjective perspective. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2569-2572. [PMID: 26827711 DOI: 10.1016/j.bbamem.2016.01.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 01/19/2016] [Accepted: 01/21/2016] [Indexed: 11/29/2022]
Abstract
Cell membranes have developed a tremendous complexity of lipids and proteins geared to perform the functions cells require. The lipids have for long remained in the background and are now regaining their role as important building blocks of cells. Their main function is to form the matrix of our cell membranes where they support a variety of functions essential for life. This 2-dimensional fluid matrix has evolved unexpected material properties that involve both lipid-lipid and lipid-protein interactions. This perspective is a short summary of the challenges that this field faces and discusses potential ways and means for coming to grips with the properties of this incredible fluid. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Kai Simons
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany.
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87
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Whitlock JM, Hartzell HC. A Pore Idea: the ion conduction pathway of TMEM16/ANO proteins is composed partly of lipid. Pflugers Arch 2016; 468:455-73. [PMID: 26739711 PMCID: PMC4751199 DOI: 10.1007/s00424-015-1777-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/14/2015] [Accepted: 12/16/2015] [Indexed: 01/04/2023]
Abstract
Since their first descriptions, ion channels have been conceived as proteinaceous conduits that facilitate the passage of ionic cargo between segregated environments. This concept is reinforced by crystallographic structures of cation channels depicting ion conductance pathways completely lined by protein. Although lipids are sometimes present in fenestrations near the pore or may be involved in channel gating, there is little or no evidence that lipids inhabit the ion conduction pathway. Indeed, the presence of lipid acyl chains in the conductance pathway would curse the design of the channel's aqueous pore. Here, we make a speculative proposal that anion channels in the TMEM16/ANO superfamily have ion conductance pathways composed partly of lipids. Our reasoning is based on the idea that TMEM16 ion channels evolved from a kind of lipid transporter that scrambles lipids between leaflets of the membrane bilayer and the modeled structural similarity between TMEM16 lipid scramblases and TMEM16 anion channels. This novel view of the TMEM16 pore offers explanation for the biophysical and pharmacological oddness of TMEM16A. We build upon the recent X-ray structure of nhTMEM16 and develop models of both TMEM16 ion channels and lipid scramblases to bolster our proposal. It is our hope that this model of the TMEM16 pore will foster innovative investigation into TMEM16 function.
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Affiliation(s)
- Jarred M Whitlock
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - H Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA.
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88
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Nickels JD, Smith JC, Cheng X. Lateral organization, bilayer asymmetry, and inter-leaflet coupling of biological membranes. Chem Phys Lipids 2015; 192:87-99. [DOI: 10.1016/j.chemphyslip.2015.07.012] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/20/2015] [Accepted: 07/25/2015] [Indexed: 11/28/2022]
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89
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The phospholipid code: a key component of dying cell recognition, tumor progression and host-microbe interactions. Cell Death Differ 2015; 22:1893-905. [PMID: 26450453 DOI: 10.1038/cdd.2015.122] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 08/05/2015] [Accepted: 08/06/2015] [Indexed: 02/06/2023] Open
Abstract
A significant effort is made by the cell to maintain certain phospholipids at specific sites. It is well described that proteins involved in intracellular signaling can be targeted to the plasma membrane and organelles through phospholipid-binding domains. Thus, the accumulation of a specific combination of phospholipids, denoted here as the 'phospholipid code', is key in initiating cellular processes. Interestingly, a variety of extracellular proteins and pathogen-derived proteins can also recognize or modify phospholipids to facilitate the recognition of dying cells, tumorigenesis and host-microbe interactions. In this article, we discuss the importance of the phospholipid code in a range of physiological and pathological processes.
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90
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91
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Boisramé-Helms J, Toti F, Hasselmann M, Meziani F. Lipid emulsions for parenteral nutrition in critical illness. Prog Lipid Res 2015; 60:1-16. [PMID: 26416578 DOI: 10.1016/j.plipres.2015.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Revised: 08/10/2015] [Accepted: 08/19/2015] [Indexed: 12/26/2022]
Abstract
Critical illness is a life-threatening multisystem process that can result in significant morbidity and mortality. In most patients, critical illness is preceded by a physiological deterioration, characterized by a catabolic state and intense metabolic changes, resulting in malnutrition and impaired immune functions. In this context, parenteral lipid emulsions may modulate inflammatory and immune reactions, depending on their fatty acid composition. These effects appear to be based on complex modifications in the composition and structure of cell membranes, through eicosanoid and cytokine synthesis and by modulation of gene expression. The pathophysiological mechanisms underlying these fatty acid-induced immune function alterations in critical ill patients are however complex and partially understood. Indeed, despite a very abundant literature, experimental and clinical data remain contradictory. The optimization of lipid emulsion composition thus represents a major challenge for clinical medicine, to adequately modulate the inflammatory pathways. In the present review, we first address the metabolic response to aggression, the effects of parenteral lipid emulsions on inflammation and immunity, and finally the controversial place of these lipid emulsions during critical illness. The analysis furthermore highlights the pathophysiological mechanisms underlying the differential effects of lipid emulsions and their potential for improving the handling of critically ill patients.
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Affiliation(s)
- Julie Boisramé-Helms
- Service de Réanimation Médicale, Nouvel Hôpital Civil, Hôpitaux Universitaires de Strasbourg, 1 place de l'Hôpital, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg, EA 7293, Faculté de médecine, Université de Strasbourg, 4 rue Koeberlé, 67000 Strasbourg, France
| | - Florence Toti
- UMR 7213 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Michel Hasselmann
- Service de Réanimation Médicale, Nouvel Hôpital Civil, Hôpitaux Universitaires de Strasbourg, 1 place de l'Hôpital, 67000 Strasbourg, France
| | - Ferhat Meziani
- Service de Réanimation Médicale, Nouvel Hôpital Civil, Hôpitaux Universitaires de Strasbourg, 1 place de l'Hôpital, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg, EA 7293, Faculté de médecine, Université de Strasbourg, 4 rue Koeberlé, 67000 Strasbourg, France.
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92
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Richard VR, Beach A, Piano A, Leonov A, Feldman R, Burstein MT, Kyryakov P, Gomez-Perez A, Arlia-Ciommo A, Baptista S, Campbell C, Goncharov D, Pannu S, Patrinos D, Sadri B, Svistkova V, Victor A, Titorenko VI. Mechanism of liponecrosis, a distinct mode of programmed cell death. Cell Cycle 2015; 13:3707-26. [PMID: 25483081 DOI: 10.4161/15384101.2014.965003] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
An exposure of the yeast Saccharomyces cerevisiae to exogenous palmitoleic acid (POA) elicits "liponecrosis," a mode of programmed cell death (PCD) which differs from the currently known PCD subroutines. Here, we report the following mechanism for liponecrotic PCD. Exogenously added POA is incorporated into POA-containing phospholipids that then amass in the endoplasmic reticulum membrane, mitochondrial membranes and the plasma membrane. The buildup of the POA-containing phospholipids in the plasma membrane reduces the level of phosphatidylethanolamine in its extracellular leaflet, thereby increasing plasma membrane permeability for small molecules and committing yeast to liponecrotic PCD. The excessive accumulation of POA-containing phospholipids in mitochondrial membranes impairs mitochondrial functionality and causes the excessive production of reactive oxygen species in mitochondria. The resulting rise in cellular reactive oxygen species above a critical level contributes to the commitment of yeast to liponecrotic PCD by: (1) oxidatively damaging numerous cellular organelles, thereby triggering their massive macroautophagic degradation; and (2) oxidatively damaging various cellular proteins, thus impairing cellular proteostasis. Several cellular processes in yeast exposed to POA can protect cells from liponecrosis. They include: (1) POA oxidation in peroxisomes, which reduces the flow of POA into phospholipid synthesis pathways; (2) POA incorporation into neutral lipids, which prevents the excessive accumulation of POA-containing phospholipids in cellular membranes; (3) mitophagy, a selective macroautophagic degradation of dysfunctional mitochondria, which sustains a population of functional mitochondria needed for POA incorporation into neutral lipids; and (4) a degradation of damaged, dysfunctional and aggregated cytosolic proteins, which enables the maintenance of cellular proteostasis.
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Key Words
- CFU, colony forming units
- CL, cardiolipin
- Cvt, cytoplasm-to-vacuole pathway
- ER, endoplasmic reticulum
- IMM, inner mitochondrial membrane
- LD, lipid droplets
- NL, neutral lipids
- PA, phosphatidic acid
- PC, phosphatidylcholine
- PCD, programmed cell death
- PE, phosphatidylethanolamine
- PI, phosphatidylinositol
- PL, phospholipids
- PM, plasma membrane
- POA, palmitoleic acid
- PS, phosphatidylserine
- ROS, reactive oxygen species
- TAG, triacylglycerols
- WT, wild-type
- apoptosis
- autophagy
- cellular proteostasis
- lipid metabolism in cellular organelles
- mechanisms of programmed cell death
- mitochondria,
- mitophagy
- plasma membrane
- signal transduction
- yeast
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Affiliation(s)
- Vincent R Richard
- a Department of Biology ; Concordia University ; Montreal , QC Canada
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93
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Wronowska W, Charzyńska A, Nienałtowski K, Gambin A. Computational modeling of sphingolipid metabolism. BMC SYSTEMS BIOLOGY 2015; 9:47. [PMID: 26275400 PMCID: PMC4537549 DOI: 10.1186/s12918-015-0176-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 06/05/2015] [Indexed: 12/13/2022]
Abstract
Background As suggested by the origin of the word, sphingolipids are mysterious molecules with various roles in antagonistic cellular processes such as autophagy, apoptosis, proliferation and differentiation. Moreover, sphingolipids have recently been recognized as important messengers in cellular signaling pathways. Notably, sphingolipid metabolism disorders have been observed in various pathological conditions such as cancer and neurodegeneration. Results The existing formal models of sphingolipid metabolism focus mainly on de novo ceramide synthesis or are limited to biochemical transformations of particular subspecies. Here, we propose the first comprehensive computational model of sphingolipid metabolism in human tissue. Contrary to the previous approaches, we use a model that reflects cell compartmentalization thereby highlighting the differences among individual organelles. Conclusions The model that we present here was validated using recently proposed methods of model analysis, allowing to detect the most sensitive and experimentally non-identifiable parameters and determine the main sources of model variance. Moreover, we demonstrate the usefulness of our model in the study of molecular processes underlying Alzheimer’s disease, which are associated with sphingolipid metabolism. Electronic supplementary material The online version of this article (doi:10.1186/s12918-015-0176-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Weronika Wronowska
- Institute of Computer Science Polish Academy of Sciences, Warsaw, Poland.
| | - Agata Charzyńska
- Faculty of Biology University of Warsaw, Warsaw, Poland. .,Bioinformatics Laboratory, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland.
| | - Karol Nienałtowski
- Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland.
| | - Anna Gambin
- Institute of Informatics, University of Warsaw, Warsaw, Poland.
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94
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Poulsen LR, López-Marqués RL, Pedas PR, McDowell SC, Brown E, Kunze R, Harper JF, Pomorski TG, Palmgren M. A phospholipid uptake system in the model plant Arabidopsis thaliana. Nat Commun 2015; 6:7649. [PMID: 26212235 DOI: 10.1038/ncomms8649] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 05/28/2015] [Indexed: 01/11/2023] Open
Abstract
Plants use solar energy to produce lipids directly from inorganic elements and are not thought to require molecular systems for lipid uptake from the environment. Here we show that Arabidopsis thaliana Aminophospholipid ATPase10 (ALA10) is a P4-type ATPase flippase that internalizes exogenous phospholipids across the plasma membrane, after which they are rapidly metabolized. ALA10 expression and phospholipid uptake are high in the epidermal cells of the root tip and in guard cells, the latter of which regulate the size of stomatal apertures to modulate gas exchange. ALA10-knockout mutants exhibit reduced phospholipid uptake at the root tips and guard cells and are affected in growth and transpiration. The presence of a phospholipid uptake system in plants is surprising. Our results suggest that one possible physiological role of this system is to internalize lysophosphatidylcholine, a signalling lipid involved in root development and stomatal control.
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Affiliation(s)
- Lisbeth R Poulsen
- Department of Plant and Environmental Sciences, Centre for Membrane Pumps in Cells and Disease-PUMPKIN, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Rosa L López-Marqués
- Department of Plant and Environmental Sciences, Centre for Membrane Pumps in Cells and Disease-PUMPKIN, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Pai R Pedas
- Department of Plant and Environmental Sciences, Centre for Membrane Pumps in Cells and Disease-PUMPKIN, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Stephen C McDowell
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, 1664 N. Virginia Street-MS330, Reno, Nevada 89557, USA
| | - Elizabeth Brown
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, 1664 N. Virginia Street-MS330, Reno, Nevada 89557, USA
| | - Reinhard Kunze
- Dahlem Centre of Plant Sciences (DCPS), Freie Universität Berlin, Institut für Biologie - Angewandte Genetik, Albrecht-Thaer-Weg 6, D-14195 Berlin, Germany
| | - Jeffrey F Harper
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, 1664 N. Virginia Street-MS330, Reno, Nevada 89557, USA
| | - Thomas G Pomorski
- Department of Plant and Environmental Sciences, Centre for Membrane Pumps in Cells and Disease-PUMPKIN, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Michael Palmgren
- Department of Plant and Environmental Sciences, Centre for Membrane Pumps in Cells and Disease-PUMPKIN, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
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95
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Giang H, Schick M. How cholesterol could be drawn to the cytoplasmic leaf of the plasma membrane by phosphatidylethanolamine. Biophys J 2015; 107:2337-44. [PMID: 25418302 DOI: 10.1016/j.bpj.2014.10.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 10/14/2014] [Accepted: 10/15/2014] [Indexed: 01/18/2023] Open
Abstract
In the mammalian plasma membrane, cholesterol can translocate rapidly between the exoplasmic and cytoplasmic leaves, so that its distribution between them should be given by the equality of its chemical potential in the leaves. Due to its favorable interaction with sphingomyelin, which is almost entirely in the outer leaf, one expects the great majority of cholesterol to be there also. Experimental results do not support this, implying that there is some mechanism attracting cholesterol to the inner leaf. We hypothesize that it is drawn there to reduce the bending free energy of the membrane caused by the presence of PE (phosphatidylethanolamine). It does this in two ways: first by simply diluting the amount of PE in the inner leaf, and second by ordering the tails of the PE to reduce its spontaneous curvature. Incorporating this mechanism into a model free energy for the bilayer, we find that between 50 and 60% of the total cholesterol should be in the inner leaf of human erythrocytes.
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Affiliation(s)
- Ha Giang
- Department of Physics, University of Washington, Seattle, Washington
| | - M Schick
- Department of Physics, University of Washington, Seattle, Washington.
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96
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Nyholm TK. Lipid-protein interplay and lateral organization in biomembranes. Chem Phys Lipids 2015; 189:48-55. [DOI: 10.1016/j.chemphyslip.2015.05.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 05/27/2015] [Accepted: 05/29/2015] [Indexed: 01/07/2023]
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97
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Yu K, Whitlock JM, Lee K, Ortlund EA, Yuan Cui Y, Hartzell HC. Identification of a lipid scrambling domain in ANO6/TMEM16F. eLife 2015; 4:e06901. [PMID: 26057829 PMCID: PMC4477620 DOI: 10.7554/elife.06901] [Citation(s) in RCA: 133] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 06/08/2015] [Indexed: 12/22/2022] Open
Abstract
Phospholipid scrambling (PLS) is a ubiquitous cellular mechanism involving the regulated bidirectional transport of phospholipids down their concentration gradient between membrane leaflets. ANO6/TMEM16F has been shown to be essential for Ca(2+)-dependent PLS, but controversy surrounds whether ANO6 is a phospholipid scramblase or an ion channel like other ANO/TMEM16 family members. Combining patch clamp recording with measurement of PLS, we show that ANO6 elicits robust Ca(2+)-dependent PLS coinciding with ionic currents that are explained by ionic leak during phospholipid translocation. By analyzing ANO1-ANO6 chimeric proteins, we identify a domain in ANO6 necessary for PLS and sufficient to confer this function on ANO1, which normally does not scramble. Homology modeling shows that the scramblase domain forms an unusual hydrophilic cleft that faces the lipid bilayer and may function to facilitate translocation of phospholipid between membrane leaflets. These findings provide a mechanistic framework for understanding PLS and how ANO6 functions in this process.
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Affiliation(s)
- Kuai Yu
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - Jarred M Whitlock
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - Kyleen Lee
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - Eric A Ortlund
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
- Department of Biochemistry, Emory University School of Medicine, Atlanta, United States
| | - Yuan Yuan Cui
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - H Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
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98
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Marquardt D, Geier B, Pabst G. Asymmetric lipid membranes: towards more realistic model systems. MEMBRANES 2015; 5:180-96. [PMID: 25955841 PMCID: PMC4496639 DOI: 10.3390/membranes5020180] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 04/28/2015] [Indexed: 01/23/2023]
Abstract
Despite the ubiquity of transbilayer asymmetry in natural cell membranes, the vast majority of existing research has utilized chemically well-defined symmetric liposomes, where the inner and outer bilayer leaflets have the same composition. Here, we review various aspects of asymmetry in nature and in model systems in anticipation for the next phase of model membrane studies.
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Affiliation(s)
- Drew Marquardt
- Institute of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Humboldtstr 50/III, Graz, 8010, Austria.
- BioTechMed-Graz, Graz, 8010, Austria.
| | - Barbara Geier
- Institute of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Humboldtstr 50/III, Graz, 8010, Austria.
- BioTechMed-Graz, Graz, 8010, Austria.
| | - Georg Pabst
- Institute of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Humboldtstr 50/III, Graz, 8010, Austria.
- BioTechMed-Graz, Graz, 8010, Austria.
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99
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Phoenix DA, Harris F, Mura M, Dennison SR. The increasing role of phosphatidylethanolamine as a lipid receptor in the action of host defence peptides. Prog Lipid Res 2015; 59:26-37. [PMID: 25936689 DOI: 10.1016/j.plipres.2015.02.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 02/26/2015] [Accepted: 02/27/2015] [Indexed: 01/04/2023]
Abstract
Host defence peptides (HDPs) are antimicrobial agents produced by organisms across the prokaryotic and eukaryotic kingdoms. Many prokaryotes produce HDPs, which utilise lipid and protein receptors in the membranes of bacterial competitors to facilitate their antibacterial action and thereby survive in their niche environment. As a major example, it is well established that cinnamycin and duramycins from Streptomyces have a high affinity for phosphatidylethanolamine (PE) and exhibit activity against other Gram-positive organisms, such as Bacillus. In contrast, although eukaryotic HDPs utilise membrane interactive mechanisms to facilitate their antimicrobial activity, the prevailing view has long been that these mechanisms do not involve membrane receptors. However, this view has been recently challenged by reports that a number of eukaryotic HDPs such as plant cyclotides also use PE as a receptor to promote their antimicrobial activities. Here, we review current understanding of the mechanisms that underpin the use of PE as a receptor in the antimicrobial and other biological actions of HDPs and describe medical and biotechnical uses of these peptides, which range from tumour imaging and detection to inclusion in topical microbicidal gels to prevent the sexual transmission of HIV.
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Affiliation(s)
- David A Phoenix
- School of Applied Science, London South Bank University, 103 Borough Road, London SE1 0AA, UK.
| | - Frederick Harris
- School of Applied Science, London South Bank University, 103 Borough Road, London SE1 0AA, UK; School of Forensic and Investigative Science, University of Central Lancashire, Preston PR1 2HE, UK
| | - Manuela Mura
- School of Mathematics and Physics, College of Science, University of Lincoln, Brayford Pool, Lincoln, Lincolnshire LN6 7TS, UK
| | - Sarah R Dennison
- School of Applied Science, London South Bank University, 103 Borough Road, London SE1 0AA, UK; School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston PR1 2HE, UK
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100
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Roelants FM, Su BM, von Wulffen J, Ramachandran S, Sartorel E, Trott AE, Thorner J. Protein kinase Gin4 negatively regulates flippase function and controls plasma membrane asymmetry. ACTA ACUST UNITED AC 2015; 208:299-311. [PMID: 25646086 PMCID: PMC4315245 DOI: 10.1083/jcb.201410076] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In yeast, the protein kinase Gin4 locally controls plasma membrane lipid asymmetry, which is necessary for optimal cytokinesis. Plasma membrane function requires distinct leaflet lipid compositions. Two of the P-type ATPases (flippases) in yeast, Dnf1 and Dnf2, translocate aminoglycerophospholipids from the outer to the inner leaflet, stimulated via phosphorylation by cortically localized protein kinase Fpk1. By monitoring Fpk1 activity in vivo, we found that Fpk1 was hyperactive in cells lacking Gin4, a protein kinase previously implicated in septin collar assembly. Gin4 colocalized with Fpk1 at the cortical site of future bud emergence and phosphorylated Fpk1 at multiple sites, which we mapped. As judged by biochemical and phenotypic criteria, a mutant (Fpk111A), in which 11 sites were mutated to Ala, was hyperactive, causing increased inward transport of phosphatidylethanolamine. Thus, Gin4 is a negative regulator of Fpk1 and therefore an indirect negative regulator of flippase function. Moreover, we found that decreasing flippase function rescued the growth deficiency of four different cytokinesis mutants, which suggests that the primary function of Gin4 is highly localized control of membrane lipid asymmetry and is necessary for optimal cytokinesis.
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Affiliation(s)
- Françoise M Roelants
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Brooke M Su
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Joachim von Wulffen
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Subramaniam Ramachandran
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Elodie Sartorel
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Amy E Trott
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Jeremy Thorner
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
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