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Selectivity of phospholipid hydrolysis by phospholipase A 2 enzymes in activated cells leading to polyunsaturated fatty acid mobilization. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:772-783. [PMID: 30010011 DOI: 10.1016/j.bbalip.2018.07.002] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/08/2018] [Accepted: 07/10/2018] [Indexed: 12/14/2022]
Abstract
Phospholipase A2s are enzymes that hydrolyze the fatty acid at the sn-2 position of the glycerol backbone of membrane glycerophospholipids. Given the asymmetric distribution of fatty acids within phospholipids, where saturated fatty acids tend to be present at the sn-1 position, and polyunsaturated fatty acids such as those of the omega-3 and omega-6 series overwhelmingly localize in the sn-2 position, the phospholipase A2 reaction is of utmost importance as a regulatory checkpoint for the mobilization of these fatty acids and the subsequent synthesis of proinflammatory omega-6-derived eicosanoids on one hand, and omega-3-derived specialized pro-resolving mediators on the other. The great variety of phospholipase A2s, their differential substrate selectivity under a variety of pathophysiological conditions, as well as the different compartmentalization of each enzyme and accessibility to substrate, render this class of enzymes also key to membrane phospholipid remodeling reactions, and the generation of specific lipid mediators not related with canonical metabolites of omega-6 or omega-3 fatty acids. This review highlights novel findings regarding the selective hydrolysis of phospholipids by phospholipase A2s and the influence this may have on the ability of these enzymes to generate distinct lipid mediators with essential functions in biological processes. This brings a new understanding of the cellular roles of these enzymes depending upon activation conditions.
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2
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Hellwing C, Tigistu-Sahle F, Fuhrmann H, Käkelä R, Schumann J. Lipid composition of membrane microdomains isolated detergent-free from PUFA supplemented RAW264.7 macrophages. J Cell Physiol 2017; 233:2602-2612. [DOI: 10.1002/jcp.26138] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 08/03/2017] [Indexed: 12/14/2022]
Affiliation(s)
- Christine Hellwing
- Clinic for Anesthesiology and Surgical Intensive Care; University Hospital Halle (Saale); Halle (Saale) Germany
| | - Feven Tigistu-Sahle
- Division of Physiology and Neuroscience, Department of Biosciences; Helsinki University Lipidomics Unit, University of Helsinki; Helsinki Finland
| | - Herbert Fuhrmann
- Institute of Biochemistry; Faculty of Veterinary Medicine, University of Leipzig; Leipzig Germany
| | - Reijo Käkelä
- Division of Physiology and Neuroscience, Department of Biosciences; Helsinki University Lipidomics Unit, University of Helsinki; Helsinki Finland
| | - Julia Schumann
- Clinic for Anesthesiology and Surgical Intensive Care; University Hospital Halle (Saale); Halle (Saale) Germany
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Tigistu-Sahle F, Lampinen M, Kilpinen L, Holopainen M, Lehenkari P, Laitinen S, Käkelä R. Metabolism and phospholipid assembly of polyunsaturated fatty acids in human bone marrow mesenchymal stromal cells. J Lipid Res 2016; 58:92-110. [PMID: 27856675 DOI: 10.1194/jlr.m070680] [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: 07/08/2016] [Revised: 11/08/2016] [Indexed: 01/06/2023] Open
Abstract
High arachidonic acid (20:4n-6) and low n-3 PUFA levels impair the capacity of cultured human bone marrow mesenchymal stromal cells (hBMSCs) to modulate immune functions. The capacity of the hBMSCs to modify PUFA structures was found to be limited. Therefore, different PUFA supplements given to the cells resulted in very different glycerophospholipid (GPL) species profiles and substrate availability for phospholipases, which have preferences for polar head group and acyl chains when liberating PUFA precursors for production of lipid mediators. When supplemented with 20:4n-6, the cells increased prostaglandin E2 secretion. However, they elongated 20:4n-6 to the less active precursor, 22:4n-6, and also incorporated it into triacylglycerols, which may have limited the proinflammatory signaling. The n-3 PUFA precursor, 18:3n-3, had little potency to reduce the GPL 20:4n-6 content, while the eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) acid supplements efficiently displaced the 20:4n-6 acyls, and created diverse GPL species substrate pools allowing attenuation of inflammatory signaling. The results emphasize the importance of choosing appropriate PUFA supplements for in vitro hBMSC expansion and suggests that for optimal function they require an exogenous fatty acid source providing 20:5n-3 and 22:6n-3 sufficiently, but 20:4n-6 moderately, which calls for specifically designed optimal PUFA supplements for the cultures.
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Affiliation(s)
| | - Milla Lampinen
- Department of Biosciences University of Helsinki, Helsinki, Finland
| | - Lotta Kilpinen
- Department of Biosciences University of Helsinki, Helsinki, Finland.,Advanced Therapies and Product Development, Finnish Red Cross Blood Service, Helsinki, Finland
| | - Minna Holopainen
- Advanced Therapies and Product Development, Finnish Red Cross Blood Service, Helsinki, Finland
| | - Petri Lehenkari
- Institute of Biomedicine, Division of Surgery, University of Oulu and Clinical Research Centre, Department of Surgery and Intensive Care, Oulu, Finland.,Department of Anatomy and Cell Biology, University of Oulu, Finland and Institute of Clinical Medicine, Division of Surgery, University of Oulu and Clinical Research Centre, Department of Surgery and Intensive Care, Oulu, Finland
| | - Saara Laitinen
- Advanced Therapies and Product Development, Finnish Red Cross Blood Service, Helsinki, Finland
| | - Reijo Käkelä
- Department of Biosciences University of Helsinki, Helsinki, Finland
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Batchu KC, Hänninen S, Jha SK, Jeltsch M, Somerharju P. Factors regulating the substrate specificity of cytosolic phospholipase A 2 -alpha in vitro. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1597-1604. [DOI: 10.1016/j.bbalip.2016.06.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 06/28/2016] [Accepted: 06/30/2016] [Indexed: 10/21/2022]
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Hermansson M, Hänninen S, Hokynar K, Somerharju P. The PNPLA-family phospholipases involved in glycerophospholipid homeostasis of HeLa cells. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1058-1065. [DOI: 10.1016/j.bbalip.2016.06.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/25/2016] [Accepted: 06/10/2016] [Indexed: 12/17/2022]
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6
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Batchu KC, Hokynar K, Jeltsch M, Mattonet K, Somerharju P. Substrate efflux propensity is the key determinant of Ca2+-independent phospholipase A-β (iPLAβ)-mediated glycerophospholipid hydrolysis. J Biol Chem 2015; 290:10093-103. [PMID: 25713085 DOI: 10.1074/jbc.m115.642835] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Indexed: 12/13/2022] Open
Abstract
The A-type phospholipases (PLAs) are key players in glycerophospholipid (GPL) homeostasis and in mammalian cells; Ca(2+)-independent PLA-β (iPLAβ) in particular has been implicated in this essential process. However, the regulation of this enzyme, which is necessary to avoid futile competition between synthesis and degradation, is not understood. Recently, we provided evidence that the efflux of the substrate molecules from the bilayer is the rate-limiting step in the hydrolysis of GPLs by some secretory (nonhomeostatic) PLAs. To study whether this is the case with iPLAβ as well, a mass spectrometric assay was employed to determine the rate of hydrolysis of multiple saturated and unsaturated GPL species in parallel using micelles or vesicle bilayers as the macrosubstrate. With micelles, the hydrolysis decreased with increasing acyl chain length independent of unsaturation, and modest discrimination between acyl positional isomers was observed, presumably due to the differences in the structure of the sn-1 and sn-2 acyl-binding sites of the protein. In striking contrast, no significant discrimination between positional isomers was observed with bilayers, and the rate of hydrolysis decreased with the acyl chain length logarithmically and far more than with micelles. These data provide compelling evidence that efflux of the substrate molecule from the bilayer, which also decreases monotonously with acyl chain length, is the rate-determining step in iPLAβ-mediated hydrolysis of GPLs in membranes. This finding is intriguing as it may help to understand how homeostatic PLAs are regulated and how degradation and biosynthesis are coordinated.
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Affiliation(s)
| | - Kati Hokynar
- From the Departments of Biochemistry and Developmental Biology and
| | - Michael Jeltsch
- Biomedicine, Faculty of Medicine, University of Helsinki, Helsinki 00014, Finland
| | - Kenny Mattonet
- Biomedicine, Faculty of Medicine, University of Helsinki, Helsinki 00014, Finland
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Laabei M, Jamieson WD, Lewis SE, Diggle SP, Jenkins ATA. A new assay for rhamnolipid detection-important virulence factors of Pseudomonas aeruginosa. Appl Microbiol Biotechnol 2014; 98:7199-209. [PMID: 24974281 DOI: 10.1007/s00253-014-5904-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 06/17/2014] [Accepted: 06/18/2014] [Indexed: 10/25/2022]
Abstract
Rhamnolipids (RLs) are heterogeneous glycolipid molecules that are composed of one or two L-rhamnose sugars and one or two β-hydroxy fatty acids, which can vary in their length and branch size. They are biosurfactants, predominantly produced by Pseudomonas aeruginosa and are important virulence factors, playing a major role in P. aeruginosa pathogenesis. Therefore, a fast, accurate and high-throughput method of detecting such molecules is of real importance. Here, we illustrate the ability to detect RL-producing P. aeruginosa strains with high sensitivity, based on an assay involving phospholipid vesicles encapsulated with a fluorescent dye. This vesicle-lysis assay is confirmed to be solely sensitive to RLs. We illustrate a half maximum concentration for vesicle lysis (EC50) of 40 μM (23.2 μg/mL) using pure commercial RLs and highlight the ability to semi-quantify RLs directly from the culture supernatant, requiring no extra extraction or processing steps or technical expertise. We show that this method is consistent with results from thin-layer chromatography detection and dry weight analysis of RLs but find that the widely used orcinol colorimetric test significantly underestimated RL quantity. Finally, we apply this methodology to compare RL production among strains isolated from either chronic or acute infections. We confirm a positive association between RL production and acute infection isolates (p = 0.0008), highlighting the role of RLs in certain infections.
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Affiliation(s)
- Maisem Laabei
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
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Zhang L, Díaz–Díaz N, Zarringhalam K, Hermansson M, Somerharju P, Chuang J. Dynamics of the ethanolamine glycerophospholipid remodeling network. PLoS One 2012; 7:e50858. [PMID: 23251394 PMCID: PMC3519547 DOI: 10.1371/journal.pone.0050858] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 10/29/2012] [Indexed: 12/18/2022] Open
Abstract
Acyl chain remodeling in lipids is a critical biochemical process that plays a central role in disease. However, remodeling remains poorly understood, despite massive increases in lipidomic data. In this work, we determine the dynamic network of ethanolamine glycerophospholipid (PE) remodeling, using data from pulse-chase experiments and a novel bioinformatic network inference approach. The model uses a set of ordinary differential equations based on the assumptions that (1) sn1 and sn2 acyl positions are independently remodeled; (2) remodeling reaction rates are constant over time; and (3) acyl donor concentrations are constant. We use a novel fast and accurate two-step algorithm to automatically infer model parameters and their values. This is the first such method applicable to dynamic phospholipid lipidomic data. Our inference procedure closely fits experimental measurements and shows strong cross-validation across six independent experiments with distinct deuterium-labeled PE precursors, demonstrating the validity of our assumptions. In constrast, fits of randomized data or fits using random model parameters are worse. A key outcome is that we are able to robustly distinguish deacylation and reacylation kinetics of individual acyl chain types at the sn1 and sn2 positions, explaining the established prevalence of saturated and unsaturated chains in the respective positions. The present study thus demonstrates that dynamic acyl chain remodeling processes can be reliably determined from dynamic lipidomic data.
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Affiliation(s)
- Lu Zhang
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
| | | | - Kourosh Zarringhalam
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
| | - Martin Hermansson
- Institute of Biomedicine, Department of Biochemistry and Developmental Biology, University of Helsinki, Helsinki, Finland
| | - Pentti Somerharju
- Institute of Biomedicine, Department of Biochemistry and Developmental Biology, University of Helsinki, Helsinki, Finland
| | - Jeffrey Chuang
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
- * E-mail:
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9
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Cheng KH, Virtanen J, Somerharju P. Calorimetric behavior of phosphatidylcholine/phosphatidylethanolamine bilayers is compatible with the superlattice model. J Phys Chem B 2012; 116:1802-11. [PMID: 22251448 DOI: 10.1021/jp2078488] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Differential scanning calorimetry was used to study the phase behavior of binary lipid bilayers consisting of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) of varying acyl chain length. A two-state transition model was used to resolve the individual transition components, and the two-state transition enthalpy, the relative enthalpy, and the transition temperature of each component were plotted as a function of composition. Intriguingly, abrupt changes in these thermodynamic parameters were observed at or close to many "critical" X(PE) values predicted by the superlattice model proposing that phospholipids with different headgroups tend to adopt regular rather than random lateral distributions. Statistical analysis indicated that the agreement between the observed and predicted "critical" compositions is highly significant. Accordingly, these data provide strong evidence that the molecules in PC/PE bilayers tend to adopt regular, superlattice-like lateral arrangements, which could be involved in the regulation of the lipid compositions of biological membranes.
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Affiliation(s)
- Kwan Hon Cheng
- Department of Physics and Astronomy, Trinity University, San Antonio, Texas 78212-7200, USA.
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Lähdesmäki K, Öörni K, Alanne-Kinnunen M, Jauhiainen M, Hurt-Camejo E, Kovanen PT. Acidity and lipolysis by group V secreted phospholipase A2 strongly increase the binding of apoB-100-containing lipoproteins to human aortic proteoglycans. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:257-67. [DOI: 10.1016/j.bbalip.2011.10.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 10/11/2011] [Accepted: 10/17/2011] [Indexed: 11/16/2022]
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Hermansson M, Hokynar K, Somerharju P. Mechanisms of glycerophospholipid homeostasis in mammalian cells. Prog Lipid Res 2011; 50:240-57. [DOI: 10.1016/j.plipres.2011.02.004] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 02/21/2011] [Accepted: 02/25/2011] [Indexed: 01/09/2023]
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12
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Jansen M, Ohsaki Y, Rega LR, Bittman R, Olkkonen VM, Ikonen E. Role of ORPs in sterol transport from plasma membrane to ER and lipid droplets in mammalian cells. Traffic 2010; 12:218-31. [PMID: 21062391 DOI: 10.1111/j.1600-0854.2010.01142.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this study, we investigated the mechanisms of sterol transport from the plasma membrane (PM) to the endoplasmic reticulum (ER) and lipid droplets (LDs) in HeLa cells. By overexpressing all mammalian oxysterol-binding protein-related proteins (ORPs), we found that especially ORP1S and ORP2 enhanced PM-to-LD sterol transport. This reflected the stimulation of transport from the PM to the ER, rather than from the ER to LDs. Double knockdown of ORP1S and ORP2 inhibited sterol transport from the PM to the ER and LDs, suggesting a physiological role for these ORPs in the process. A two phenylalanines in an acidic tract (FFAT) motif in ORPs that mediates interaction with VAMP-associated proteins (VAPs) in the ER was not necessary for the enhancement of sterol transport by ORPs. However, VAP-A and VAP-B silencing slowed down PM-to-LD sterol transport. This was accompanied by enhanced degradation of ORP2 and decreased levels of several FFAT motif-containing ORPs, suggesting a role for VAPs in sterol transport by stabilization of ORPs.
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Affiliation(s)
- Maurice Jansen
- Institute of Biomedicine, University of Helsinki, Finland
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13
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Cannon B, Lewis A, Somerharju P, Virtanen J, Huang J, Cheng KH. Acyl-chain mismatch driven superlattice arrangements in DPPC/DLPC/cholesterol bilayers. J Phys Chem B 2010; 114:10105-13. [PMID: 20684633 DOI: 10.1021/jp105104f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Fluorescence and infrared spectroscopy and cholesterol oxidase activity were employed to investigate the effect of phosphatidylcholine (PC) acyl chain length mismatch on the lateral organizations of lipids in liquid-ordered dipalmitoyl-PC/dilauroyl-PC/cholesterol (DPPC/DLPC/CHOL) bilayers. Plots of steady-state fluorescence emission anisotropy of diphenylhexatriene (DPH) labeled PC (DPH-PC) embedded in the DPPC/DLPC/CHOL bilayers revealed significant peaks at several DPPC mole fractions (Y(DPPC)) when the cholesterol mole fraction (X(CHOL)) was fixed to particular values. Analogously, the DPH-PC anisotropy peaked at several critical X(CHOL)'s when Y(DPPC) was fixed. Acyl chain C-H and C horizontal lineO vibrational peak frequencies of native PC as well as the activity of cholesterol oxidase also revealed dips and peaks at similar Y(DPPC)'s. Importantly, most of the observed peaks/dips coincide with the critical mole fractions predicted by the Superlattice (SL) model. A three-dimensional map of DPH-PC anisotropy versus composition in the range 0.32 <or= X(CHOL) <or= 0.50; 0.54 <or= Y(DPPC) <or= 0.72 revealed a prominent peak at (X(CHOL), Y(DPPC)) approximately (0.42, 0.64). This suggests a simultaneous presence of two different types of superlattices, one where cholesterol is the quest molecule in a PC host lattice and another where DPPC is the guest in the DLPC host lattice. Time-resolved measurements of DPH-PC fluorescence indicated the existence of an ordered, rotationally hindered environment of acyl chains at that "critical" composition consistent with the existence of SL arrangements. We propose that beside CHOL/PC superlattices, DPPC, and DLPC as well tend to adopt regular SL-like lateral distributions relative to each other, presumably because the less hydrophobic DLPC molecule is slightly displaced toward the aqueous phase, thus allowing more room and mobility for the head groups of both DPPC and DLPC as well as for the acyl chain tails of DPPC. The parallel presence of two kinds of superlattices, that is, CHOL/PC-SL and DPPC/DLPC-SL as demonstrated here, has intriguing implications regarding lipid homeostasis of eukaryote membranes.
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Affiliation(s)
- Brian Cannon
- Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 79712, USA.
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