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Pennington ER, Virk R, Bridges MD, Bathon BE, Beatty N, Gray RS, Kelley P, Wassall SR, Manke J, Armstrong M, Reisdorph N, Vanduinen R, Fenton JI, Gowdy KM, Shaikh SR. Docosahexaenoic Acid Controls Pulmonary Macrophage Lipid Raft Size and Inflammation. J Nutr 2024:S0022-3166(24)00174-3. [PMID: 38582385 DOI: 10.1016/j.tjnut.2024.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 03/27/2024] [Accepted: 04/02/2024] [Indexed: 04/08/2024] Open
Abstract
BACKGROUND Docosahexaenoic acid (DHA) controls the biophysical organization of plasma membrane sphingolipid/cholesterol-enriched lipid rafts to exert anti-inflammatory effects, particularly in lymphocytes. However, the impact of DHA on the spatial arrangement of alveolar macrophage lipid rafts and inflammation is unknown. OBJECTIVES The primary objective was to determine how DHA controls lipid raft organization and function of alveolar macrophages. As proof-of-concept, we also investigated DHA's anti-inflammatory effects on select pulmonary inflammatory markers with a murine influenza model. METHODS MH-S cells, an alveolar macrophage line, were treated with 50 μM DHA or vehicle control and were used to study plasma membrane molecular organization with fluorescence-based methods. Biomimetic membranes and coarse grain molecular dynamic (MD) simulations were employed to investigate how DHA mechanistically controls lipid raft size. qRT-PCR, mass spectrometry, and ELISAs were used to quantify downstream inflammatory signaling transcripts, oxylipins, and cytokines, respectively. Lungs from DHA-fed influenza-infected mice were analyzed for specific inflammatory markers. RESULTS DHA increased the size of lipid rafts while decreasing the molecular packing of the MH-S plasma membrane. Adding a DHA-containing phospholipid to a biomimetic lipid raft-containing membrane led to condensing, which was reversed with the removal of cholesterol. MD simulations revealed DHA nucleated lipid rafts by driving cholesterol and sphingomyelin into rafts. Downstream of the plasma membrane, DHA lowered the concentration of select inflammatory transcripts, oxylipins, and IL-6 secretion. DHA lowered pulmonary Il6 and Tnf-α mRNA expression and increased anti-inflammatory oxylipins of influenza-infected mice. CONCLUSIONS The data suggest a model in which the localization of DHA acyl chains to nonrafts is driving sphingomyelin and cholesterol molecules into larger lipid rafts, which may serve as a trigger to impede signaling and lower inflammation. These findings also identify alveolar macrophages as a target of DHA and underscore the anti-inflammatory properties of DHA for lung inflammation.
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Affiliation(s)
- Edward Ross Pennington
- Department of Nutrition, Gillings School of Global Public Health & School of Medicine, University of North Carolina at Chapel Hill, NC, United States
| | - Rafia Virk
- Department of Nutrition, Gillings School of Global Public Health & School of Medicine, University of North Carolina at Chapel Hill, NC, United States
| | - Meagan D Bridges
- Department of Nutrition, Gillings School of Global Public Health & School of Medicine, University of North Carolina at Chapel Hill, NC, United States
| | - Brooke E Bathon
- Department of Nutrition, Gillings School of Global Public Health & School of Medicine, University of North Carolina at Chapel Hill, NC, United States
| | - Nari Beatty
- Department of Nutrition, Gillings School of Global Public Health & School of Medicine, University of North Carolina at Chapel Hill, NC, United States
| | - Rosemary S Gray
- Department of Nutrition, Gillings School of Global Public Health & School of Medicine, University of North Carolina at Chapel Hill, NC, United States
| | - Patrick Kelley
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN, United States
| | - Stephen R Wassall
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN, United States
| | - Jonathan Manke
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Michael Armstrong
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Nichole Reisdorph
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Rachel Vanduinen
- Department of Food Science and Human Nutrition, College of Agriculture and Natural Resources, Michigan State University, East Lansing, MI, United States
| | - Jenifer I Fenton
- Department of Food Science and Human Nutrition, College of Agriculture and Natural Resources, Michigan State University, East Lansing, MI, United States
| | - Kymberly M Gowdy
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, the Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Saame Raza Shaikh
- Department of Nutrition, Gillings School of Global Public Health & School of Medicine, University of North Carolina at Chapel Hill, NC, United States.
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Cavazos AT, Pennington ER, Dadoo S, Gowdy KM, Wassall SR, Shaikh SR. OxPAPC stabilizes liquid-ordered domains in biomimetic membranes. Biophys J 2023; 122:1130-1139. [PMID: 36840353 PMCID: PMC10111260 DOI: 10.1016/j.bpj.2023.02.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 11/16/2022] [Accepted: 02/17/2023] [Indexed: 02/26/2023] Open
Abstract
Long-chain polyunsaturated fatty acids (PUFAs) are prone to nonenzymatic oxidation in response to differing environmental stressors and endogenous cellular sources. There is increasing evidence that phospholipids containing oxidized PUFA acyl chains control the inflammatory response. However, the underlying mechanism(s) of action by which oxidized PUFAs exert their functional effects remain unclear. Herein, we tested the hypothesis that replacement of 1-palmitoyl-2-arachidonyl-phosphatidylcholine (PAPC) with oxidized 1-palmitoyl-2-arachidonyl-phosphatidylcholine (oxPAPC) regulates membrane architecture. Specifically, with solid-state 2H NMR of biomimetic membranes, we investigated how substituting oxPAPC for PAPC modulates the molecular organization of liquid-ordered (Lo) domains. 2H NMR spectra for bilayer mixtures of 1,2-dipalmitoylphosphatidylcholine-d62 (an analog of DPPC deuterated throughout sn-1 and -2 chains) and cholesterol to which PAPC or oxPAPC was added revealed that replacing PAPC with oxPAPC disrupted molecular organization, indicating that oxPAPC does not mix favorably in a tightly packed Lo phase. Furthermore, unlike PAPC, adding oxPAPC stabilized 1,2-dipalmitoylphosphatidylcholine-d6-rich/cholesterol-rich Lo domains formed in mixtures with 1,2-dioleoylphosphatidylcholine while decreasing the molecular order within 1,2-dioleoylphosphatidylcholine-rich liquid-disordered regions of the membrane. Collectively, these results suggest a mechanism in which oxPAPC stabilizes Lo domains-by disordering the surrounding liquid-disordered region. Changes in the structure, and thereby functionality, of Lo domains may underly regulation of plasma membrane-based inflammatory signaling by oxPAPC.
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Affiliation(s)
- Andres T Cavazos
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis Indiana
| | - Edward Ross Pennington
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill North Carolina
| | - Sahil Dadoo
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill North Carolina
| | - Kymberly M Gowdy
- Pulmonary, Critical Care and Sleep Medicine, Ohio State University Wexner Medical Center, Davis Heart and Lung Research Institute, Columbus, Ohio
| | - Stephen R Wassall
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis Indiana.
| | - Saame Raza Shaikh
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill North Carolina.
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Shafieenezhad A, Mitra S, Wassall SR, Tristram-Nagle S, Nagle JF, Petrache HI. Location of dopamine in lipid bilayers and its relevance to neuromodulator function. Biophys J 2023; 122:1118-1129. [PMID: 36804668 PMCID: PMC10111280 DOI: 10.1016/j.bpj.2023.02.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 11/18/2022] [Accepted: 02/13/2023] [Indexed: 02/18/2023] Open
Abstract
Dopamine (DA) is a neurotransmitter that also acts as a neuromodulator, with both functions being essential to brain function. Here, we present the first experimental measurement of DA location in lipid bilayers using x-ray diffuse scattering, solid-state deuterium NMR, and electron paramagnetic resonance. We find that the association of DA with lipid headgroups as seen in electron density profiles leads to an increase of intermembrane repulsion most likely due to electrostatic charging. DA location in the lipid headgroup region also leads to an increase of the cross-sectional area per lipid without affecting the bending rigidity significantly. The order parameters measured by solid-state deuterium NMR decrease in the presence of DA for the acyl chains of PC and PS lipids, consistent with an increase in the area per lipid due to DA. Most importantly, these results support the hypothesis that three-dimensional diffusion of DA to target membranes could be followed by relatively more efficient two-dimensional diffusion to receptors within those membranes.
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Affiliation(s)
- Azam Shafieenezhad
- Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana
| | - Saheli Mitra
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Stephen R Wassall
- Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana
| | | | - John F Nagle
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Horia I Petrache
- Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana.
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Cavazos AT, Canner SW, Leng X, Petrache HI, Wassall SR. Cholesterol promotes similar chain packing in n-3 PUFA-containing membranes. Biophys J 2023; 122:82a. [PMID: 36785036 DOI: 10.1016/j.bpj.2022.11.651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Andres T Cavazos
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN, USA
| | - Samuel W Canner
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN, USA
| | - Xiaoling Leng
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN, USA
| | - Horia I Petrache
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN, USA
| | - Stephen R Wassall
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN, USA
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Cavazos AT, Wassall SR, Pal A, Shaikh SR. A role for oxidized phospholipids in regulating membrane architecture? Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.1652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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6
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Shafieenezhad A, Wassall SR, Tristram-Nagle SA, Nagle JF, Petrache HI. The effect of dopamine on model lipid membrane structure. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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7
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Canner SW, Feller SE, Wassall SR. Molecular Organization of a Raft-like Domain in a Polyunsaturated Phospholipid Bilayer: A Supervised Machine Learning Analysis of Molecular Dynamics Simulations. J Phys Chem B 2021; 125:13158-13167. [PMID: 34812629 DOI: 10.1021/acs.jpcb.1c06511] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Numerous health benefits are associated with omega-3 polyunsaturated fatty acids (n-3 PUFA) consumed in fish oils. An understanding of the mechanism remains elusive. The plasma membrane as a site of action is the focus in this study. With large-scale all-atom MD simulations run on a model membrane (1050 lipid molecules), we observed the evolution over time (6 μs) of a circular (raft-like) domain composed of N-palmitoylsphingomyelin (PSM) and cholesterol embedded into a surrounding (non-raft) patch composed of polyunsaturated 1-palmitoyl-2-docosahexaenoylphosphatylcholine (PDPC) (1:1:1 mol). A supervised machine learning algorithm was developed to characterize the migration of each lipid based on molecular conformation and the local environment. PDPC molecules were seen to infiltrate the ordered raft-like domain in a small amount, while a small concentration of PSM and cholesterol molecules was seen to migrate into the disordered non-raft region. Enclosing the raft-like domain, a narrow (∼2 nm in width) interfacial zone composed of PDPC, PSM, and cholesterol that buffers the substantial difference in order (ΔSCD ≈ 0.12) between raft-like and non-raft environments was seen to form. Our results suggest that n-3 PUFA regulate the architecture of lipid rafts enriched in sphingolipids and cholesterol with a minimal effect on order within their interior in membranes.
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Affiliation(s)
- Samuel W Canner
- Department of Physics, IUPUI, Indianapolis, Indiana 46202-3273, United States.,Department of Computer and Information Science, IUPUI, Indianapolis, Indiana 46202-5132, United States
| | - Scott E Feller
- Department of Chemistry, Wabash College, Crawfordsville, Indiana 47933, United States
| | - Stephen R Wassall
- Department of Physics, IUPUI, Indianapolis, Indiana 46202-3273, United States
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Cavazos AT, Pal A, Dadoo S, Wassall SR, Raza Shaikh S. Molecular Organization of Lipid Rafts is Modified by Oxidized Phosphatidylcholines. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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9
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Doktorova M, Kučerka N, Kinnun JJ, Pan J, Marquardt D, Scott HL, Venable RM, Pastor RW, Wassall SR, Katsaras J, Heberle FA. Molecular Structure of Sphingomyelin in Fluid Phase Bilayers Determined by the Joint Analysis of Small-Angle Neutron and X-ray Scattering Data. J Phys Chem B 2020; 124:5186-5200. [PMID: 32468822 DOI: 10.1021/acs.jpcb.0c03389] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We have determined the fluid bilayer structure of palmitoyl sphingomyelin (PSM) and stearoyl sphingomyelin (SSM) by simultaneously analyzing small-angle neutron and X-ray scattering data. Using a newly developed scattering density profile (SDP) model for sphingomyelin lipids, we report structural parameters including the area per lipid, total bilayer thickness, and hydrocarbon thickness, in addition to lipid volumes determined by densitometry. Unconstrained all-atom simulations of PSM bilayers at 55 °C using the C36 CHARMM force field produced a lipid area of 56 Å2, a value that is 10% lower than the one determined experimentally by SDP analysis (61.9 Å2). Furthermore, scattering form factors calculated from the unconstrained simulations were in poor agreement with experimental form factors, even though segmental order parameter (SCD) profiles calculated from the simulations were in relatively good agreement with SCD profiles obtained from NMR experiments. Conversely, constrained area simulations at 61.9 Å2 resulted in good agreement between the simulation and experimental scattering form factors, but not with SCD profiles from NMR. We discuss possible reasons for the discrepancies between these two types of data that are frequently used as validation metrics for molecular dynamics force fields.
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Affiliation(s)
- Milka Doktorova
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas 77030, United States
| | - Norbert Kučerka
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, 141980 Dubna, Russia.,Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University, 814 99 Bratislava, Slovakia
| | - Jacob J Kinnun
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Jianjun Pan
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Drew Marquardt
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4, Canada
| | - Haden L Scott
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Richard M Venable
- Laboratory of Computational Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Richard W Pastor
- Laboratory of Computational Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Stephen R Wassall
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - John Katsaras
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Frederick A Heberle
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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Cavazos AT, Kinnun JJ, Williams JA, Wassall SR. Vitamin E - phosphatidylethanolamine interactions in mixed membranes with sphingomyelin: Studies by 2H NMR. Chem Phys Lipids 2020; 231:104910. [PMID: 32492380 DOI: 10.1016/j.chemphyslip.2020.104910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/14/2020] [Accepted: 03/21/2020] [Indexed: 01/13/2023]
Abstract
Among the structurally diverse collection of lipids that comprise the membrane lipidome, polyunsaturated phospholipids are particularly vulnerable to oxidation. The role of α-tocopherol (vitamin E) is to protect this influential class of membrane phospholipid from oxidative damage. Whether lipid-lipid interactions play a role in supporting this function is an unanswered question. Here, we compare the molecular organization of polyunsaturated 1-[2H31]palmitoyl-2-docosahexaenoylphosphatidylethanolamine (PDPE-d31) and, as a control, monounsaturated 1-[2H31]palmitoyl-2-oleoylphosphatidylethanolamine (POPE-d31) mixed with sphingomyelin (SM) and α-tocopherol (α-toc) (2:2:1 mol) by solid-state 2H NMR spectroscopy. In both cases the effect of α-toc appears similar. Spectral moments reveal that the main chain melting transition of POPE-d31 and PDPE-d31 is broadened beyond detection. A spectral component attributed to the formation of inverted hexagonal HII phase in coexistence with lamellar Lα phase by POPE-d31 (20 %) and PDPE-d31 (18 %) is resolved following the addition of α-toc. Order parameters in the remaining Lα phase are increased slightly more for POPE-d31 (7%) than PDPE-d31 (4%). Preferential interaction with polyunsaturated phospholipid is not apparent in these results. The propensity for α-toc to form phase structure with negative curvature that is more tightly packed at the membrane surface, nevertheless, may restrict the contact of free radicals with lipid chains on phosphatidylethanolamine molecules that accumulate polyunsaturated fatty acids.
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Affiliation(s)
- Andres T Cavazos
- Department of Physics, Indiana University-Purdue University, Indianapolis, IN, 46202, United States
| | - Jacob J Kinnun
- Department of Physics, Indiana University-Purdue University, Indianapolis, IN, 46202, United States
| | - Justin A Williams
- Department of Physics, Indiana University-Purdue University, Indianapolis, IN, 46202, United States
| | - Stephen R Wassall
- Department of Physics, Indiana University-Purdue University, Indianapolis, IN, 46202, United States.
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Harper PE, Cavazos AT, Kinnun JJ, Petrache HI, Wassall SR. Vitamin E Promotes the Inverse Hexagonal Phase via a Novel Mechanism: Implications for Antioxidant Role. Langmuir 2020; 36:4908-4916. [PMID: 32295345 DOI: 10.1021/acs.langmuir.0c00176] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Vitamin E (α-tocopherol) and a range of other biological compounds have long been known to promote the HII (inverted hexagonal) phase in lipids. Now, it has been well established that purely hydrophobic lipids such as dodecane promote the HII phase by relieving extensive packing stress. They do so by residing deep within the hydrocarbon core. However, we argue from X-ray diffraction data obtained with 1-palmitoyl-2-oleoylphosphatidylcholine (POPE) and 1,2-dioleoylphosphatidylcholine (DOPE) that α-tocopherol promotes the HII phase by a different mechanism. The OH group on the chromanol moiety of α-tocopherol anchors it near the aqueous interface. This restriction combined with the relatively short length of α-tocopherol (as compared to DOPE and POPE) means that α-tocopherol promotes the HII phase by relieving compressive packing stress. This observation offers new insight into the nature of packing stress and lipid biophysics. With the deeper understanding of packing stress offered by our results, we also explore the role that molecular structure plays in the primary function of vitamin E, which is to prevent the oxidation of polyunsaturated membrane lipids.
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Affiliation(s)
- Paul E Harper
- Department of Physics and Astronomy, Calvin University, Grand Rapids, Michigan 49546-4403, United States
| | - Andres T Cavazos
- Department of Physics, IUPUI, Indianapolis, Indiana 46202-3273, United States
| | - Jacob J Kinnun
- Department of Physics, IUPUI, Indianapolis, Indiana 46202-3273, United States
| | - Horia I Petrache
- Department of Physics, IUPUI, Indianapolis, Indiana 46202-3273, United States
| | - Stephen R Wassall
- Department of Physics, IUPUI, Indianapolis, Indiana 46202-3273, United States
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Cavazos AT, Wassall SR. ESR Spectroscopy Determines the Affinity of Cholesterol for Lipids with Varying Degrees of Unsaturation. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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13
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Canner SW, Phillips AQ, Feller SI, Wassall SR. Vitamin E's Affinity for Polyunsaturated Phospholipids Studied by All-Atom MD Simulations. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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14
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Shafieenezhad A, Cavazos AT, Ramkumar A, Wassall SR, Petrache HI. Order Parameter Analysis of Lipids Organization in the Presence of ATP. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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15
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Kinnun JJ, Bittman R, Shaikh SR, Wassall SR. DHA Modifies the Size and Composition of Raftlike Domains: A Solid-State 2H NMR Study. Biophys J 2019; 114:380-391. [PMID: 29401435 DOI: 10.1016/j.bpj.2017.11.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 11/14/2017] [Accepted: 11/17/2017] [Indexed: 01/22/2023] Open
Abstract
Docosahexaenoic acid is an omega-3 polyunsaturated fatty acid that relieves the symptoms of a wide variety of chronic inflammatory disorders. The structural mechanism is not yet completely understood. Our focus here is on the plasma membrane as a site of action. We examined the molecular organization of [2H31]-N-palmitoylsphingomyelin (PSM-d31) mixed with 1-palmitoyl-2-docosahexaenoylphosphatylcholine (PDPC) or 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), as a monounsaturated control, and cholesterol (chol) (1:1:1 mol) in a model membrane by solid-state 2H NMR. The spectra were analyzed in terms of segregation into ordered SM-rich/chol-rich (raftlike) and disordered PC-rich/chol-poor (nonraft) domains that are nanoscale in size. An increase in the size of domains is revealed when POPC was replaced by PDPC. Spectra that are single-component, attributed to fast exchange between domains (<45 nm), for PSM-d31 mixed with POPC and chol become two-component, attributed to slow exchange between domains (r > 30 nm), for PSM-d31 mixed with PDPC and chol. The resolution of separate signals from PSM-d31, and correspondingly from [3α-2H1]cholesterol (chol-d1) and 1-[2H31]palmitoyl-2-docosahexaenoylphosphatidylcholine (PDPC-d31), in raftlike and nonraft domains enabled us to determine the composition of the domains in the PDPC-containing membrane. Most of the lipid (28% SM, 29% chol, and 23% PDPC with respect to total lipid at 30°C) was found in the raftlike domain. Despite substantial infiltration of PDPC into raftlike domains, there appears to be minimal effect on the order of SM, implying the existence of internal structure that limits contact between SM and PDPC. Our results suggest a significant refinement to the model by which DHA regulates the architecture of ordered, sphingolipid-chol-enriched domains (rafts) in membranes.
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Affiliation(s)
- Jacob J Kinnun
- Department of Physics, Indiana University-Purdue University, Indianapolis, Indiana
| | - Robert Bittman
- Department of Chemistry and Biochemistry, Queens College of CUNY, Flushing, New York
| | - Saame Raza Shaikh
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Stephen R Wassall
- Department of Physics, Indiana University-Purdue University, Indianapolis, Indiana.
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Cavazos AT, Harper PE, Kinnun JJ, Petrache HI, Wassall SR. Vitamin E Promotes the Inverse Hexagonal Phase Providing Insights on Lipid Packing Stresses: Studies by SAXS and 2H NMR. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.1240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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17
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Canner SW, Zhu F, Feller SE, Wassall SR. A Role for Lipid-Lipid Interactions in Vitamin E's Function as a Membrane Antioxidant. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.1251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Leng X, Zhu F, Wassall SR. Vitamin E Has Reduced Affinity for a Polyunsaturated Phospholipid: An Umbrella Sampling Molecular Dynamics Simulations Study. J Phys Chem B 2018; 122:8351-8358. [PMID: 30111105 DOI: 10.1021/acs.jpcb.8b05016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Vitamin E is an essential micronutrient. The primary function of this lipid-soluble antioxidant is to protect membrane phospholipids from oxidation. Whether vitamin E preferentially interacts with polyunsaturated phospholipids to optimize protection of the lipid species most vulnerable to oxidative attack has been an unanswered question for a long time. In this work, we compared the binding of α-tocopherol (αtoc), the form of vitamin E retained by the human body, in bilayers composed of polyunsaturated 1-stearoyl-2-docosahexaenoylphosphatidylcholine (SDPC, 18:0-22:6PC) and, as a control, monounsaturated 1-stearoyl-2-oleoylphosphatidylcholine (SOPC, 18:0-18:1PC) by umbrella sampling molecular dynamics simulations. From the potential of mean force as a function depth within the bilayer, we find that the binding energy of αtoc is less in SDPC (Δ Gbind = 16.7 ± 0.3 kcal/mol) than that in SOPC (Δ Gbind = 18.3 ± 0.4 kcal/mol). The lower value in SDPC is ascribed to the high disorder of polyunsaturated fatty acids that produces a less tightly packed arrangement. Deformation of the bilayer is observed during desorption, indicating that phosphatidylcholine (PC)-PC and αtoc-PC interactions contribute to the binding energy. Our results do not support the proposal that vitamin E interacts more favorably with polyunsaturated phospholipids.
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Affiliation(s)
- Xiaoling Leng
- Department of Physics , IUPUI , Indianapolis , Indiana 46202-3273 , United States
| | - Fangqiang Zhu
- Department of Physics , IUPUI , Indianapolis , Indiana 46202-3273 , United States
| | - Stephen R Wassall
- Department of Physics , IUPUI , Indianapolis , Indiana 46202-3273 , United States
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Wassall SR, Leng X, Canner SW, Pennington ER, Kinnun JJ, Cavazos AT, Dadoo S, Johnson D, Heberle FA, Katsaras J, Shaikh SR. Docosahexaenoic acid regulates the formation of lipid rafts: A unified view from experiment and simulation. Biochim Biophys Acta Biomembr 2018; 1860:1985-1993. [PMID: 29730243 DOI: 10.1016/j.bbamem.2018.04.016] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Revised: 04/27/2018] [Accepted: 04/28/2018] [Indexed: 01/02/2023]
Abstract
Docosahexaenoic acid (DHA, 22:6) is an n-3 polyunsaturated fatty acid (n-3 PUFA) that influences immunological, metabolic, and neurological responses through complex mechanisms. One structural mechanism by which DHA exerts its biological effects is through its ability to modify the physical organization of plasma membrane signaling assemblies known as sphingomyelin/cholesterol (SM/chol)-enriched lipid rafts. Here we studied how DHA acyl chains esterified in the sn-2 position of phosphatidylcholine (PC) regulate the formation of raft and non-raft domains in mixtures with SM and chol on differing size scales. Coarse grained molecular dynamics simulations showed that 1-palmitoyl-2-docosahexaenoylphosphatylcholine (PDPC) enhances segregation into domains more than the monounsaturated control, 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC). Solid state 2H NMR and neutron scattering experiments provided direct experimental evidence that substituting PDPC for POPC increases the size of raft-like domains on the nanoscale. Confocal imaging of giant unilamellar vesicles with a non-raft fluorescent probe revealed that POPC had no influence on phase separation in the presence of SM/chol whereas PDPC drove strong domain segregation. Finally, monolayer compression studies suggest that PDPC increases lipid-lipid immiscibility in the presence of SM/chol compared to POPC. Collectively, the data across model systems provide compelling support for the emerging model that DHA acyl chains of PC lipids tune the size of lipid rafts, which has potential implications for signaling networks that rely on the compartmentalization of proteins within and outside of rafts.
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Affiliation(s)
- Stephen R Wassall
- Department of Physics, Indiana University-Purdue University Indianapolis, United States.
| | - Xiaoling Leng
- Department of Physics, Indiana University-Purdue University Indianapolis, United States
| | - Samuel W Canner
- Department of Physics, Indiana University-Purdue University Indianapolis, United States; Department of Computer and Information Science, Indiana University-Purdue University Indianapolis, United States
| | - Edward Ross Pennington
- Department of Biochemistry & Molecular Biology, East Carolina University, United States; Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, United States
| | - Jacob J Kinnun
- Department of Physics, Indiana University-Purdue University Indianapolis, United States
| | - Andres T Cavazos
- Department of Physics, Indiana University-Purdue University Indianapolis, United States
| | - Sahil Dadoo
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, United States
| | - Dylan Johnson
- Department of Biochemistry & Molecular Biology, East Carolina University, United States
| | - Frederick A Heberle
- Joint Institute for Biological Sciences, University of Tennessee, Knoxville, TN, United States; Large Scale Structures Group, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - John Katsaras
- Large Scale Structures Group, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN, United States; Shull Wollan Center-Joint Institute for Neutron Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Saame Raza Shaikh
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, United States.
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Leng X, Kinnun JJ, Cavazos AT, Canner SW, Shaikh SR, Feller SE, Wassall SR. All n-3 PUFA are not the same: MD simulations reveal differences in membrane organization for EPA, DHA and DPA. Biochim Biophys Acta Biomembr 2018; 1860:1125-1134. [PMID: 29305832 PMCID: PMC5963985 DOI: 10.1016/j.bbamem.2018.01.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 12/19/2017] [Accepted: 01/01/2018] [Indexed: 01/01/2023]
Abstract
Eicosapentaenoic (EPA, 20:5), docosahexaenoic (DHA, 22:6) and docosapentaenoic (DPA, 22:5) acids are omega-3 polyunsaturated fatty acids (n-3 PUFA) obtained from dietary consumption of fish oils that potentially alleviate the symptoms of a range of chronic diseases. We focus here on the plasma membrane as a site of action and investigate how they affect molecular organization when taken up into a phospholipid. All atom MD simulations were performed to compare 1-stearoyl-2-eicosapentaenoylphosphatylcholine (EPA-PC, 18:0-20:5PC), 1-stearoyl-2-docosahexaenoylphosphatylcholine (DHA-PC, 18:0-22:6PC), 1-stearoyl-2-docosapentaenoylphosphatylcholine (DPA-PC, 18:0-22:5PC) and, as a monounsaturated control, 1-stearoyl-2-oleoylphosphatidylcholine (OA-PC, 18:0-18:1PC) bilayers. They were run in the absence and presence of 20mol% cholesterol. Multiple double bonds confer high disorder on all three n-3 PUFA. The different number of double bonds and chain length for each n-3 PUFA moderates the reduction in membrane order exerted (compared to OA-PC, S¯CD=0.152). EPA-PC (S¯CD=0.131) is most disordered, while DPA-PC (S¯CD=0.140) is least disordered. DHA-PC (S¯CD=0.139) is, within uncertainty, the same as DPA-PC. Following the addition of cholesterol, order in EPA-PC (S¯CD=0.169), DHA-PC (S¯CD=0.178) and DPA-PC (S¯CD=0.182) is increased less than in OA-PC (S¯CD=0.214). The high disorder of n-3 PUFA is responsible, preventing the n-3 PUFA-containing phospholipids from packing as close to the rigid sterol as the monounsaturated control. Our findings establish that EPA, DHA and DPA are not equivalent in their interactions within membranes, which possibly contributes to differences in clinical efficacy.
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Affiliation(s)
- Xiaoling Leng
- Department of Physics, IUPUI, Indianapolis, IN 46202-3273, United States
| | - Jacob J Kinnun
- Department of Physics, IUPUI, Indianapolis, IN 46202-3273, United States
| | - Andres T Cavazos
- Department of Physics, IUPUI, Indianapolis, IN 46202-3273, United States
| | - Samuel W Canner
- Department of Physics, IUPUI, Indianapolis, IN 46202-3273, United States; Department of Computer Science and Information Science, IUPUI, Indianapolis, IN 46202-5132, United States
| | - Saame Raza Shaikh
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States
| | - Scott E Feller
- Department of Chemistry, Wabash College, Crawfordsville, IN 47933, United States
| | - Stephen R Wassall
- Department of Physics, IUPUI, Indianapolis, IN 46202-3273, United States.
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Canner SW, Leng X, Zhu F, Wassall SR. Are Vitamin E and PUFA Driven Together by Choleterol? Computer Simulation Studies. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Cavazos AT, Bell ME, Leach ZL, Kinnun JJ, Wassall SR. Phospholipid Head Groups Provide Differentially Stable Membrane Environments for Vitamin E. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.2043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Kinnun JJ, Leng X, Johnson D, Pennington ER, Meador AJ, Raza Shaikh S, Wassall SR. Raft-Like Domains are Driven Together by Pufa. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.1729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Marquardt D, Heberle FA, Greathouse DV, Koeppe RE, Standaert RF, Van Oosten BJ, Harroun TA, Kinnun JJ, Williams JA, Wassall SR, Katsaras J. Lipid bilayer thickness determines cholesterol's location in model membranes. Soft Matter 2016; 12:9417-9428. [PMID: 27801465 DOI: 10.1039/c6sm01777k] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Cholesterol is an essential biomolecule of animal cell membranes, and an important precursor for the biosynthesis of certain hormones and vitamins. It is also thought to play a key role in cell signaling processes associated with functional plasma membrane microdomains (domains enriched in cholesterol), commonly referred to as rafts. In all of these diverse biological phenomena, the transverse location of cholesterol in the membrane is almost certainly an important structural feature. Using a combination of neutron scattering and solid-state 2H NMR, we have determined the location and orientation of cholesterol in phosphatidylcholine (PC) model membranes having fatty acids of different lengths and degrees of unsaturation. The data establish that cholesterol reorients rapidly about the bilayer normal in all the membranes studied, but is tilted and forced to span the bilayer midplane in the very thin bilayers. The possibility that cholesterol lies flat in the middle of bilayers, including those made from PC lipids containing polyunsaturated fatty acids (PUFAs), is ruled out. These results support the notion that hydrophobic thickness is the primary determinant of cholesterol's location in membranes.
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Affiliation(s)
- Drew Marquardt
- Department of Physics, Brock University, St. Catharines, Ontario L2S 3A1, Canada and Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Frederick A Heberle
- The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee 37996, USA and Joint Institute for Biological Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA and Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
| | - Denise V Greathouse
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Roger E Koeppe
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Robert F Standaert
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA and Department of Biochemistry and Cellular & Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Brad J Van Oosten
- Department of Physics, Brock University, St. Catharines, Ontario L2S 3A1, Canada
| | - Thad A Harroun
- Department of Physics, Brock University, St. Catharines, Ontario L2S 3A1, Canada
| | - Jacob J Kinnun
- Department of Physics, Indiana University - Purdue University Indianapolis, Indianapolis, Indiana 46202, USA.
| | - Justin A Williams
- Department of Physics, Indiana University - Purdue University Indianapolis, Indianapolis, Indiana 46202, USA.
| | - Stephen R Wassall
- Department of Physics, Indiana University - Purdue University Indianapolis, Indianapolis, Indiana 46202, USA.
| | - John Katsaras
- Department of Physics, Brock University, St. Catharines, Ontario L2S 3A1, Canada and The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee 37996, USA and Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA. and Shull Wollan Center-a Joint Institute for Neutron Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA and Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
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Marquardt D, Kučerka N, Wassall SR, Harroun TA, Katsaras J. Cholesterol's location in lipid bilayers. Chem Phys Lipids 2016; 199:17-25. [DOI: 10.1016/j.chemphyslip.2016.04.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Revised: 04/01/2016] [Accepted: 04/02/2016] [Indexed: 02/07/2023]
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Harris M, Kinnun JJ, Kosaraju R, Leng X, Wassall SR, Shaikh SR. Membrane Disordering by Eicosapentaenoic Acid in B Lymphomas Is Reduced by Elongation to Docosapentaenoic Acid as Revealed with Solid-State Nuclear Magnetic Resonance Spectroscopy of Model Membranes. J Nutr 2016; 146:1283-9. [PMID: 27306897 PMCID: PMC4926856 DOI: 10.3945/jn.116.231639] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 04/29/2016] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Plasma membrane organization is a mechanistic target of n-3 (ω-3) polyunsaturated fatty acids. Previous studies show that eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) differentially disrupt plasma membrane molecular order to enhance the frequency and function of B lymphocytes. However, it is not known whether EPA and DHA affect the plasma membrane organization of B lymphomas differently to influence their function. OBJECTIVE We tested whether EPA and DHA had different effects on membrane order in B lymphomas and liposomes and studied their effects on B-lymphoma growth. METHODS B lymphomas were treated with 25 μmol EPA, DHA, or serum albumin control/L for 24 h. Membrane order was measured with fluorescence polarization, and cellular fatty acids (FAs) were analyzed with GC. Growth was quantified with a viability assay. (2)H nuclear magnetic resonance (NMR) studies were conducted on deuterated phospholipid bilayers. RESULTS Treating Raji, Ramos, and RPMI lymphomas for 24 h with 25 μmol EPA or DHA/L lowered plasma membrane order by 10-40% relative to the control. There were no differences between EPA and DHA on membrane order for the 3 cell lines. FA analyses revealed complex changes in response to EPA or DHA treatment and a large fraction of EPA was converted to docosapentaenoic acid (DPA; 22:5n-3). NMR studies, which were used to understand why EPA and DHA had similiar membrane effects, showed that phospholipids containing DPA, similar to DHA, were more ordered than those containing EPA. Finally, treating B lymphomas with 25 μmol EPA or DHA/L did not increase the frequency of B lymphomas compared with controls. CONCLUSIONS The results establish that 25 μmol EPA and DHA/L equally disrupt membrane order and do not promote B lymphoma growth. The data open a new area of investigation, which is how EPA's conversion to DPA substantially moderates its influence on membrane properties.
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Affiliation(s)
- Mitchell Harris
- Department of Biochemistry and Molecular Biology,,East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC; and
| | - Jacob J Kinnun
- Department of Physics, Indiana University–Purdue University Indianapolis, Indianapolis, IN
| | - Rasagna Kosaraju
- Department of Biochemistry and Molecular Biology,,East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC; and
| | - Xiaoling Leng
- Department of Physics, Indiana University–Purdue University Indianapolis, Indianapolis, IN
| | - Stephen R Wassall
- Department of Physics, Indiana University–Purdue University Indianapolis, Indianapolis, IN
| | - Saame Raza Shaikh
- Department of Biochemistry and Molecular Biology, East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC; and
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Leng X, Zhu F, Wassall SR. Binding of Vitamin E in Model Membranes Studied by Umbrella Sampling Simulations. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.3116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Kinnun JJ, Williams JA, Stillwell W, Bittman R, Shaikh SR, Wassall SR. Solid-state 2H NMR Reveals the Impact of DHA on Molecular Organization in Raft-Like Domains. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Cavazos AT, Kinnun JJ, Lybarger RZ, Williams JA, Ray BD, Harper PE, Petrache HI, Wassall SR. Vitamin E Differentially Destabilizes Bilayer Structure of Docosahexaenoic and Oleic-Acid Containing Model Membranes. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Harper PE, Cavazos AT, Kinnun JJ, Petrache HI, Wassall SR. Vitamin E Promotes the Inverse Hexagonal Phase via a Novel Mechanism: Implications for Antioxidant Role. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Leng X, Kinnun JJ, Marquardt D, Ghefli M, Kučerka N, Katsaras J, Atkinson J, Harroun TA, Feller SE, Wassall SR. α-Tocopherol Is Well Designed to Protect Polyunsaturated Phospholipids: MD Simulations. Biophys J 2015; 109:1608-18. [PMID: 26488652 PMCID: PMC4624157 DOI: 10.1016/j.bpj.2015.08.032] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 08/20/2015] [Accepted: 08/24/2015] [Indexed: 01/08/2023] Open
Abstract
The presumptive function for alpha-tocopherol (αtoc) in membranes is to protect polyunsaturated lipids against oxidation. Although the chemistry of the process is well established, the role played by molecular structure that we address here with atomistic molecular-dynamics simulations remains controversial. The simulations were run in the constant particle NPT ensemble on hydrated lipid bilayers composed of SDPC (1-stearoyl-2-docosahexaenoylphosphatidylcholine, 18:0-22:6PC) and SOPC (1-stearoyl-2-oleoylphosphatidylcholine, 18:0-18:1PC) in the presence of 20 mol % αtoc at 37°C. SDPC with SA (stearic acid) for the sn-1 chain and DHA (docosahexaenoic acid) for the sn-2 chain is representative of polyunsaturated phospholipids, while SOPC with OA (oleic acid) substituted for the sn-2 chain serves as a monounsaturated control. Solid-state (2)H nuclear magnetic resonance and neutron diffraction experiments provide validation. The simulations demonstrate that high disorder enhances the probability that DHA chains at the sn-2 position in SDPC rise up to the bilayer surface, whereby they encounter the chromanol group on αtoc molecules. This behavior is reflected in the van der Waals energy of interaction between αtoc and acyl chains, and illustrated by density maps of distribution for acyl chains around αtoc molecules that were constructed. An ability to more easily penetrate deep into the bilayer is another attribute conferred upon the chromanol group in αtoc by the high disorder possessed by DHA. By examining the trajectory of single molecules, we found that αtoc flip-flops across the SDPC bilayer on a submicrosecond timescale that is an order-of-magnitude greater than in SOPC. Our results reveal mechanisms by which the sacrificial hydroxyl group on the chromanol group can trap lipid peroxyl radicals within the interior and near the surface of a polyunsaturated membrane. At the same time, water-soluble reducing agents that regenerate αtoc can access the chromanol group when it locates at the surface.
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Affiliation(s)
- Xiaoling Leng
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - Jacob J Kinnun
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - Drew Marquardt
- Department of Physics, Brock University, St. Catharines, Ontario, Canada; Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Mikel Ghefli
- Department of Chemistry, Brock University, St. Catharines, Ontario, Canada
| | - Norbert Kučerka
- Canadian Neutron Beam Centre, National Research Council, Chalk River, Ontario, Canada; Faculty of Pharmacy, Comenius University, Bratislava, Slovakia
| | - John Katsaras
- Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Joint Institute for Neutron Sciences, Oak Ridge, Tennessee; Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee
| | - Jeffrey Atkinson
- Department of Chemistry, Brock University, St. Catharines, Ontario, Canada
| | - Thad A Harroun
- Department of Physics, Brock University, St. Catharines, Ontario, Canada
| | - Scott E Feller
- Department of Chemistry, Wabash College, Crawfordsville, Indiana
| | - Stephen R Wassall
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana.
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Abstract
Increased consumption of long-chain marine n-3 polyunsaturated fatty acids (PUFA) has potential health benefits for the general population and for select clinical populations. However, several key limitations remain in making adequate dietary recommendations on n-3 PUFAs in addition to translating the fatty acids into clinical trials for select diseases. One major constraint is an incomplete understanding of the underlying mechanisms of action of n-3 PUFAs. In this review, we highlight studies to show n-3 PUFA acyl chains reorganize the molecular architecture of plasma membrane sphingolipid-cholesterol-enriched lipid rafts and potentially sphingolipid-rich cholesterol-free domains and cardiolipin-protein scaffolds in the inner mitochondrial membrane. We also discuss the possibility that the effects of n-3 PUFAs on membrane organization could be regulated by the presence of vitamin E (α-tocopherol), which is necessary to protect highly unsaturated acyl chains from oxidation. Finally, we propose the integrated hypothesis, based predominately on studies in lymphocytes, cancer cells, and model membranes, that the mechanism by which n-3 PUFAs disrupt signaling microclusters is highly dependent on the type of lipid species that incorporate n-3 PUFA acyl chains. The current evidence suggests that n-3 PUFA acyl chains disrupt lipid raft formation by incorporating primarily into phosphatidylethanolamines but can also incorporate into other lipid species of the lipidome.
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Affiliation(s)
- Saame Raza Shaikh
- Department of Biochemistry & Molecular Biology, East Carolina University, Greenville, NC, USA; Department of Microbiology and Immunology, East Carolina University, Greenville, NC, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Stephen R Wassall
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN, USA
| | - David A Brown
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA; Department of Physiology, East Carolina University, Greenville, NC, USA
| | - Rasagna Kosaraju
- Department of Biochemistry & Molecular Biology, East Carolina University, Greenville, NC, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
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Johnson MA, Ray BD, Wassall SR, Petrache HI. Equivalent Isopropanol Concentrations of Aromatic Amino Acids Interactions with Lipid Vesicles. J Membr Biol 2015; 248:695-703. [PMID: 25691267 DOI: 10.1007/s00232-015-9781-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 01/30/2015] [Indexed: 11/26/2022]
Abstract
We show that the interaction of aromatic amino acids with lipid bilayers can be characterized by conventional 1D [Formula: see text]H NMR spectroscopy using reference spectra obtained in isopropanol-d8/D[Formula: see text]O solutions. We demonstrate the utility of this method with three different peptides containing tyrosine, tryptophan, or phenylalanine amino acids in the presence of 1,2-dioleoyl-sn-glycero-3-phosphocholine or 1,2-dioleoyl-sn-glycero-3-phosphoserine lipid membranes. In each case, we determine an equivalent isopropanol concentration (EIC) for each hydrogen site of aromatic groups, in essence constructing a map of the chemical environment. These EIC maps provide information on relative affinities of aromatic side chains for either PC or PS bilayers and also inform on amino acid orientation preference when bound to membranes.
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Affiliation(s)
- Merrell A Johnson
- Department of Physics, Indiana University Purdue University Indianapolis, 402 N Blackford St., Indianapolis, IN, 46202, USA,
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Greathouse DV, Kinnun JJ, Williams JA, Marquardt D, Klauda JB, Koeppe RE, Katsaras J, Harroun TA, Wassall SR. Disorderly Polyunsaturated Fatty Acids and Orderly Cholesterol: Just How do they get along in a Membrane? Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.2259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Kinnun JJ, Williams JA, Stillwell W, Bittman R, Shaikh SR, Wassall SR. DHA Disorders Raft-Like Domains as Revealed by Solid State 2H NMR. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.2258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Justice MJ, Petrusca DN, Rogozea AL, Williams JA, Schweitzer KS, Petrache I, Wassall SR, Petrache HI. Effects of lipid interactions on model vesicle engulfment by alveolar macrophages. Biophys J 2014; 106:598-609. [PMID: 24507600 DOI: 10.1016/j.bpj.2013.12.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 11/11/2013] [Accepted: 12/23/2013] [Indexed: 01/18/2023] Open
Abstract
The engulfment function of macrophages relies on complex molecular interactions involving both lipids and proteins. In particular, the clearance of apoptotic bodies (efferocytosis) is enabled by externalization on the cell target of phosphatidylserine lipids, which activate receptors on macrophages, suggesting that (local) specific lipid-protein interactions are required at least for the initiation of efferocytosis. However, in addition to apoptotic cells, macrophages can engulf foreign bodies that vary substantially in size from a few nanometers to microns, suggesting that nonspecific interactions over a wide range of length scales could be relevant. Here, we use model lipid membranes (made of phosphatidylcholine, phosphatidylserine, and ceramide) and rat alveolar macrophages to show how lipid bilayer properties probed by small-angle x-ray scattering and solid-state (2)H NMR correlate with engulfment rates measured by flow cytometry. We find that engulfment of protein-free model lipid vesicles is promoted by the presence of phosphatidylserine lipids but inhibited by ceramide, in accord with a previous study of apoptotic cells. We conclude that the roles of phosphatidylserine and ceramide in phagocytosis is based, at least in part, on lipid-mediated modification of membrane physical properties, including interactions at large length scales as well as local lipid ordering and possible domain formation.
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Affiliation(s)
- Matthew J Justice
- Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana; Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Daniela N Petrusca
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Adriana L Rogozea
- Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana; Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Justin A Williams
- Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana
| | - Kelly S Schweitzer
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Irina Petrache
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; Department of Medicine, Richard L. Roudebush Veterans' Affairs Medical Center, Indianapolis, Indiana
| | - Stephen R Wassall
- Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana
| | - Horia I Petrache
- Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana.
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Shaikh SR, Kinnun JJ, Leng X, Williams JA, Wassall SR. How polyunsaturated fatty acids modify molecular organization in membranes: insight from NMR studies of model systems. Biochim Biophys Acta 2014; 1848:211-9. [PMID: 24820775 DOI: 10.1016/j.bbamem.2014.04.020] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 04/23/2014] [Indexed: 11/26/2022]
Abstract
Marine long chain n-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), are bioactive molecules with clinical applications for the treatment of several diseases. In order to effectively translate these molecules into clinical trials, it is essential to establish the underlying mechanisms for n-3 PUFA. This review focuses on efforts to understand how EPA and DHA, upon incorporation into plasma membrane phospholipids, remodel the molecular organization of cholesterol-enriched lipid microdomains. We first give an overview of results from studies on cells. Paradoxical data generated from mouse studies indicate that EPA and DHA incorporate into lipid microdomains, yet in spite of their high disorder increase molecular order within the domain. We then spotlight the utility of solid state (2)H NMR spectroscopy of model bilayers as a tool for elucidating underlying mechanisms by which n-3 PUFA-containing phospholipids can regulate molecular organization of lipid microdomains. Evidence is presented demonstrating that n-3 PUFA exert differential structural effects when incorporated into phosphatidylethanolamines (PE) compared to phosphatidylcholines (PC), which explains some of the conflicting results observed in vivo. Recent studies that reveal differences between the interactions of EPA and DHA with lipid microdomains, potentially reflecting a differential in bioactivity, are finally described. Overall, we highlight the notion that NMR experiments on model membranes suggest a complex model by which n-3 PUFA reorganize lipid microdomains in vivo.
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Affiliation(s)
- Saame Raza Shaikh
- Department of Biochemistry & Molecular Biology, East Carolina Diabetes and Obesity Institute, East Carolina University, 115 Heart Drive, Room 4117, Mail Stop 743, Greenville, NC 27834, USA
| | - Jacob J Kinnun
- Department of Physics, Indiana University-Purdue University Indianapolis, 402 N. Blackford Street, Indianapolis, IN 46202-3273, USA
| | - Xiaoling Leng
- Department of Physics, Indiana University-Purdue University Indianapolis, 402 N. Blackford Street, Indianapolis, IN 46202-3273, USA
| | - Justin A Williams
- Department of Physics, Indiana University-Purdue University Indianapolis, 402 N. Blackford Street, Indianapolis, IN 46202-3273, USA
| | - Stephen R Wassall
- Department of Physics, Indiana University-Purdue University Indianapolis, 402 N. Blackford Street, Indianapolis, IN 46202-3273, USA.
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Kinnun JJ, Williams JA, Stillwell W, Bittman R, Raza Shaikh S, Wassall SR. Solid State 2H NMR Studies of the Disordering of Raft-Like Domains by n-3 PUFA. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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Marquardt D, Williams JA, Kinnun JJ, Kucerka N, Atkinson J, Wassall SR, Katsaras J, Harroun TA. DMPC: A Remarkable Exception to the Tocopherol's Membrane Presence. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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40
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Marquardt D, Williams JA, Kinnun JJ, Kučerka N, Atkinson J, Wassall SR, Katsaras J, Harroun TA. Dimyristoyl phosphatidylcholine: a remarkable exception to α-tocopherol's membrane presence. J Am Chem Soc 2013; 136:203-10. [PMID: 24308426 DOI: 10.1021/ja408288f] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using data obtained from different physical techniques (i.e., neutron diffraction, NMR and UV spectroscopy), we present evidence which explains some of the conflicting and inexplicable data found in the literature regarding α-tocopherol's (aToc's) behavior in dimyristoyl phosphatidylcholine (di-14:0PC) bilayers. Without exception, the data point to aToc's active chromanol moiety residing deep in the hydrophobic core of di-14:0PC bilayers, a location that is in stark contrast to aToc's location in other PC bilayers. Our result is a clear example of the importance of lipid species diversity in biological membranes and importantly, it suggests that measurements of aToc's oxidation kinetics, and its associated byproducts observed in di-14:0PC bilayers, should be reexamined, this time taking into account its noncanonical location in this bilayer.
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Affiliation(s)
- Drew Marquardt
- Department of Physics, Brock University , St. Catharines, Ontario L2S 3A1, Canada
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Marquardt D, Williams JA, Kučerka N, Atkinson J, Wassall SR, Katsaras J, Harroun TA. Tocopherol activity correlates with its location in a membrane: a new perspective on the antioxidant vitamin E. J Am Chem Soc 2013; 135:7523-33. [PMID: 23581571 DOI: 10.1021/ja312665r] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We show evidence of an antioxidant mechanism for vitamin E which correlates strongly with its physical location in a model lipid bilayer. These data address the overlooked problem of the physical distance between the vitamin's reducing hydrogen and lipid acyl chain radicals. Our combined data from neutron diffraction, NMR, and UV spectroscopy experiments all suggest that reduction of reactive oxygen species and lipid radicals occurs specifically at the membrane's hydrophobic-hydrophilic interface. The latter is possible when the acyl chain "snorkels" to the interface from the hydrocarbon matrix. Moreover, not all model lipids are equal in this regard, as indicated by the small differences in vitamin's location. The present result is a clear example of the importance of lipid diversity in controlling the dynamic structural properties of biological membranes. Importantly, our results suggest that measurements of aToc oxidation kinetics, and its products, should be revisited by taking into consideration the physical properties of the membrane in which the vitamin resides.
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Affiliation(s)
- Drew Marquardt
- Department of Physics, Brock University, St. Catharines, Ontario L2S 3A1, Canada
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Kinnun JJ, Williams JA, Bittman R, Shaikh SR, Wassall SR. Disordering of Raft Domains by DHA and EPA observed with Solid-State Deuterium NMR Spectroscopy. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.3271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Leng X, Williams JA, Marquardt D, Kučerka N, Katsaras J, Atkinson J, Harroun TA, Feller SE, Wassall SR. Interaction of α-Tocopherol with a Polyunsaturated Lipid Studied by MD Simulations. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.3278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Williams J, Wassall CD, Kemple MD, Wassall SR. Dependence of Cholesterol-Phospholipid Affinity on Degree of Acyl Chain Unsaturation as Determined by EPR. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.3270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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45
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Marquardt D, Kučerka N, Williams JA, Atkinson J, Wassall SR, Katsaras J, Harroun TA. The Location of Vitamin E in Model Membranes and its Effect on Oxidation. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.1404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Williams JA, Batten SE, Harris M, Rockett BD, Shaikh SR, Stillwell W, Wassall SR. Docosahexaenoic and eicosapentaenoic acids segregate differently between raft and nonraft domains. Biophys J 2012; 103:228-37. [PMID: 22853900 DOI: 10.1016/j.bpj.2012.06.016] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 06/06/2012] [Accepted: 06/12/2012] [Indexed: 01/01/2023] Open
Abstract
Omega-3 polyunsaturated fatty acids (n-3 PUFA), enriched in fish oils, are increasingly recognized to have potential benefits for treating many human afflictions. Despite the importance of PUFA, their molecular mechanism of action remains unclear. One emerging hypothesis is that phospholipids containing n-3 PUFA acyl chains modify the structure and composition of membrane rafts, thus affecting cell signaling. In this study the two major n-3 PUFA found in fish oils, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, are compared. Using solid-state (2)H NMR spectroscopy we explored the molecular organization of 1-[(2)H(31)]palmitoyl-2-eicosapentaenoylphosphatidylcholine (PEPC-d(31)) and 1-[(2)H(31)]palmitoyl-2-docosahexaenoylphosphatidylcholine (PDPC-d(31)) in mixtures with sphingomyelin (SM) and cholesterol (chol). Our results indicate that whereas both PEPC-d(31) and PDPC-d(31) can accumulate into SM-rich/chol-rich raftlike domains, the tendency for DHA to incorporate into rafts is more than twice as great as for EPA. We propose that DHA may be the more bioactive component of fish oil that serves to disrupt lipid raft domain organization. This mechanism represents an evolution in the view of how PUFA remodel membrane architecture.
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Affiliation(s)
- Justin A Williams
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, USA
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Rockett BD, Teague H, Harris M, Melton M, Williams J, Wassall SR, Shaikh SR. Fish oil increases raft size and membrane order of B cells accompanied by differential effects on function. J Lipid Res 2012; 53:674-85. [PMID: 22315394 DOI: 10.1194/jlr.m021782] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Fish oil (FO) targets lipid microdomain organization to suppress T-cell and macrophage function; however, little is known about this relationship with B cells, especially at the animal level. We previously established that a high FO dose diminished mouse B-cell lipid raft microdomain clustering induced by cross-linking GM1. To establish relevance, here we tested a FO dose modeling human intake on B-cell raft organization relative to a control. Biochemical analysis revealed more docosahexaenoic acid (DHA) incorporated into phosphatidylcholines than phosphatidylethanolamines of detergent-resistant membranes, consistent with supporting studies with model membranes. Subsequent imaging experiments demonstrated that FO increased raft size, GM1 expression, and membrane order upon cross-linking GM1 relative to no cross-linking. Comparative in vitro studies showed some biochemical differences from in vivo measurements but overall revealed that DHA, but not eicosapentaenoic acid (EPA), increased membrane order. Finally, we tested the hypothesis that disrupting rafts with FO would suppress B-cell responses ex vivo. FO enhanced LPS-induced B-cell activation but suppressed B-cell stimulation of transgenic naive CD4(+) T cells. Altogether, our studies with B cells support an emerging model that FO increases raft size and membrane order accompanied by functional changes; furthermore, the results highlight differences in EPA and DHA bioactivity.
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Affiliation(s)
- Benjamin Drew Rockett
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA
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Leng X, Williams JA, Gorman JM, Feller SE, Atkinson J, Wassall SR. Molecular Organization of Vitamin E in a Polyunsaturated Membrane. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.3534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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49
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Williams JA, Wassall CD, Kagimbi MW, Eslinger CL, Kemple MD, Wassall SR. Cholesterol-Lipid Affinity Determined by EPR. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.1625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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50
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Justice MJ, Petrusca DN, Williams J, Schweitzer KS, Petrache I, Wassall SR, Petrache HI. Engulfment of Model Membranes by Alveolar Macrophages. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.2750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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