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Suresh P, London E. MαCD-based plasma membrane outer leaflet lipid exchange in mammalian cells to study insulin receptor activity. Methods Enzymol 2024; 700:485-507. [PMID: 38971611 DOI: 10.1016/bs.mie.2024.03.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/08/2024]
Abstract
Signaling receptors on the plasma membrane, such as insulin receptor, can have their activity modulated to some extent by their surrounding lipids. Studying the contribution of membrane lipid properties such as presence of ordered lipid domains or bilayer thickness on the activity of receptors has been a challenging objective in living cells. Using methyl-alpha cyclodextrin-mediated lipid exchange, we are able to alter the lipids of the outer leaflet plasma membrane of mammalian cells to investigate the effect of the properties of the exchanged lipid upon receptor function in live cells. In this article, we describe the technique of lipid exchange in detail and how it can be applied to better understand lipid-mediated regulation of insulin receptor activity in cells.
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Affiliation(s)
- Pavana Suresh
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States.
| | - Erwin London
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, United States
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2
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Canals D, Hannun YA. Biological function, topology, and quantification of plasma membrane Ceramide. Adv Biol Regul 2024; 91:101009. [PMID: 38128364 DOI: 10.1016/j.jbior.2023.101009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 12/11/2023] [Indexed: 12/23/2023]
Abstract
Over the past 30 years, a growing body of evidence has revealed the regulatory role of the lipid ceramide in various cellular functions. The structural diversity of ceramide, resulting in numerous species, and its distinct distribution within subcellular compartments may account for its wide range of functions. However, our ability to study the potential role of ceramide in specific subcellular membranes has been limited. Several works have shown mitochondrial, Golgi, and plasma membrane ceramide to mediate signaling pathways independently. These results have started to shift the focus on ceramide signaling research toward specific membrane pools. Nonetheless, the challenge arises from the substantial intracellular ceramide content, hindering efforts to quantify its presence in particular membranes. Recently, we have developed the first method capable of detecting and quantifying ceramide in the plasma membrane, leading to unexpected results such as detecting different pools of ceramide responding to drug concentration or time. This review summarizes the historical context that defined the idea of pools of ceramide, the studies on plasma membrane ceramide as a bioactive entity, and the tools available for its study, especially the new method to detect and, for the first time, quantify plasma membrane ceramide. We believe this method will open new avenues for researching sphingolipid signaling and metabolism.
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Affiliation(s)
- Daniel Canals
- Department of Medicine, Stony Brook University, Stony Brook, NY, USA; Cancer Center, Stony Brook University, Stony Brook, NY, USA.
| | - Yusuf A Hannun
- Department of Medicine, Stony Brook University, Stony Brook, NY, USA; Cancer Center, Stony Brook University, Stony Brook, NY, USA.
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3
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Höglsperger F, Vos BE, Hofemeier AD, Seyfried MD, Stövesand B, Alavizargar A, Topp L, Heuer A, Betz T, Ravoo BJ. Rapid and reversible optical switching of cell membrane area by an amphiphilic azobenzene. Nat Commun 2023; 14:3760. [PMID: 37353493 PMCID: PMC10290115 DOI: 10.1038/s41467-023-39032-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/25/2023] [Indexed: 06/25/2023] Open
Abstract
Cellular membrane area is a key parameter for any living cell that is tightly regulated to avoid membrane damage. Changes in area-to-volume ratio are known to be critical for cell shape, but are mostly investigated by changing the cell volume via osmotic shocks. In turn, many important questions relating to cellular shape, membrane tension homeostasis and local membrane area cannot be easily addressed because experimental tools for controlled modulation of cell membrane area are lacking. Here we show that photoswitching an amphiphilic azobenzene can trigger its intercalation into the plasma membrane of various mammalian cells ranging from erythrocytes to myoblasts and cancer cells. The photoisomerization leads to a rapid (250-500 ms) and highly reversible membrane area change (ca 2 % for erythrocytes) that triggers a dramatic shape modulation of living cells.
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Affiliation(s)
- Fabian Höglsperger
- Organic Chemistry Institute, University of Münster, Münster, Germany
- Center for Soft Nanoscience, University of Münster, Münster, Germany
| | - Bart E Vos
- Third Institute of Physics-Biophysics, University of Göttingen, Göttingen, Germany
| | - Arne D Hofemeier
- Third Institute of Physics-Biophysics, University of Göttingen, Göttingen, Germany
| | - Maximilian D Seyfried
- Organic Chemistry Institute, University of Münster, Münster, Germany
- Center for Soft Nanoscience, University of Münster, Münster, Germany
| | - Bastian Stövesand
- Organic Chemistry Institute, University of Münster, Münster, Germany
- Center for Soft Nanoscience, University of Münster, Münster, Germany
| | - Azadeh Alavizargar
- Institute of Physical Chemistry, University of Münster, Münster, Germany
| | - Leon Topp
- Institute of Physical Chemistry, University of Münster, Münster, Germany
| | - Andreas Heuer
- Center for Soft Nanoscience, University of Münster, Münster, Germany
- Institute of Physical Chemistry, University of Münster, Münster, Germany
| | - Timo Betz
- Third Institute of Physics-Biophysics, University of Göttingen, Göttingen, Germany.
| | - Bart Jan Ravoo
- Organic Chemistry Institute, University of Münster, Münster, Germany.
- Center for Soft Nanoscience, University of Münster, Münster, Germany.
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4
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London E. Ordered Domain (Raft) Formation in Asymmetric Vesicles and Its Induction upon Loss of Lipid Asymmetry in Artificial and Natural Membranes. MEMBRANES 2022; 12:870. [PMID: 36135889 PMCID: PMC9503047 DOI: 10.3390/membranes12090870] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 09/01/2022] [Accepted: 09/03/2022] [Indexed: 06/16/2023]
Abstract
Lipid asymmetry, the difference in the lipid composition in the inner and outer lipid monolayers (leaflets) of a membrane, is an important feature of eukaryotic plasma membranes. Investigation of the biophysical consequences of lipid asymmetry has been aided by advances in the ability to prepare artificial asymmetric membranes, especially by use of cyclodextrin-catalyzed lipid exchange. This review summarizes recent studies with artificial asymmetric membranes which have identified conditions in which asymmetry can induce or suppress the ability of membranes to form ordered domains (rafts). A consequence of the latter effect is that, under some conditions, a loss of asymmetry can induce ordered domain formation. An analogous study in plasma membrane vesicles has demonstrated that asymmetry can also suppress domain formation in natural membranes. Thus, it is possible that a loss of asymmetry can induce domain formation in vivo.
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Affiliation(s)
- Erwin London
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
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5
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Bag N, London E, Holowka DA, Baird BA. Transbilayer Coupling of Lipids in Cells Investigated by Imaging Fluorescence Correlation Spectroscopy. J Phys Chem B 2022; 126:2325-2336. [PMID: 35294838 DOI: 10.1021/acs.jpcb.2c00117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Plasma membranes host numerous receptors, sensors, and ion channels involved in cellular signaling. Phase separation within the plasma membrane has emerged as a key biophysical regulator of signaling reactions in multiple physiological and pathological contexts. There is much evidence that plasma membrane composition supports the coexistence of liquid-ordered (Lo) and liquid-disordered (Ld) phases or domains at physiological conditions. However, this phase/domain separation is nanoscopic and transient in live cells. It has been recently proposed that transbilayer coupling between the inner and outer leaflets of the plasma membrane is driven by their asymmetric lipid distribution and by dynamic cytoskeleton-lipid composites that contribute to the formation and transience of Lo/Ld phase separation in live cells. In this Perspective, we highlight new approaches to investigate how transbilayer coupling may influence phase separation. For quantitative evaluation of the impact of these interactions, we introduce an experimental strategy centered around Imaging Fluorescence Correlation Spectroscopy (ImFCS), which measures membrane diffusion with very high precision. To demonstrate this strategy, we choose two well-established model systems for transbilayer interactions: cross-linking by multivalent antigen of immunoglobulin E bound to receptor FcεRI and cross-linking by cholera toxin B of GM1 gangliosides. We discuss emerging methods to systematically perturb membrane lipid composition, particularly exchange of outer leaflet lipids with exogenous lipids using methyl alpha cyclodextrin. These selective perturbations may be quantitatively evaluated with ImFCS and other high-resolution biophysical tools to discover novel principles of lipid-mediated phase separation in live cells in the context of their pathophysiological relevance.
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Affiliation(s)
- Nirmalya Bag
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Erwin London
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York 11794, United States
| | - David A Holowka
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Barbara A Baird
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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6
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Nazemidashtarjandi S, Sharma VM, Puri V, Farnoud AM, Burdick MM. Lipid Composition of the Cell Membrane Outer Leaflet Regulates Endocytosis of Nanomaterials through Alterations in Scavenger Receptor Activity. ACS NANO 2022; 16:2233-2248. [PMID: 35138811 PMCID: PMC10538024 DOI: 10.1021/acsnano.1c08344] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Understanding the principles that guide the uptake of engineered nanomaterials (ENMs) by cells is of interest in biomedical and occupational health research. While evidence has started to accumulate on the role of membrane proteins in ENM uptake, the role of membrane lipid chemistry in regulating ENM endocytosis has remained largely unexplored. Here, we have addressed this issue by altering the plasma membrane lipid composition directly in live cells using a methyl-α-cyclodextrin (MαCD)-catalyzed lipid exchange method. Our observations, in an alveolar epithelial cell line and using silica nanoparticles, reveal that the lipid composition of the plasma membrane outer leaflet plays a significant role in ENM endocytosis and the intracellular fate of ENMs, by affecting nonspecific ENM diffusion into the cell, changing membrane fluidity, and altering the activity of scavenger receptors (SRs) involved in active endocytosis. These results have implications for understanding ENM uptake in different subsets of cells, depending on cell membrane lipid composition.
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Affiliation(s)
- Saeed Nazemidashtarjandi
- Department of Chemical and Biomolecular Engineering, Ohio University, Athens, Ohio 45701, United States
| | - Vishva M Sharma
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio 45701, United States
| | - Vishwajeet Puri
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio 45701, United States
| | - Amir M Farnoud
- Department of Chemical and Biomolecular Engineering, Ohio University, Athens, Ohio 45701, United States
- Biomedical Engineering Program, Ohio University, Athens, Ohio 45701, United States
| | - Monica M Burdick
- Department of Chemical and Biomolecular Engineering, Ohio University, Athens, Ohio 45701, United States
- Biomedical Engineering Program, Ohio University, Athens, Ohio 45701, United States
- Edison Biotechnology Institute, Ohio University, Athens, Ohio 45701, United States
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7
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Suresh P, London E. Using cyclodextrin-induced lipid substitution to study membrane lipid and ordered membrane domain (raft) function in cells. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183774. [PMID: 34534531 PMCID: PMC9128603 DOI: 10.1016/j.bbamem.2021.183774] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/30/2021] [Accepted: 09/08/2021] [Indexed: 02/03/2023]
Abstract
Methods for efficient cyclodextrin-induced lipid exchange have been developed in our lab. These make it possible to almost completely replace the lipids in the outer leaflet of artificial membranes or the plasma membranes of living cells with exogenous lipids. Lipid replacement/substitution allows detailed studies of how lipid composition and asymmetry influence the structure and function of membrane domains and membrane proteins. In this review, we both summarize progress on cyclodextrin exchange in cells, mainly by the use of methyl-alpha cyclodextrin to exchange phospholipids and sphingolipids, and discuss the issues to consider when carrying out lipid exchange experiments upon cells. Issues that impact interpretation of lipid exchange are also discussed. This includes how overly naïve interpretation of how lipid exchange-induced changes in domain formation can impact protein function.
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8
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Ge Y, Boopathy S, Nguyen TH, Lugo CM, Chao LH. Absence of Cardiolipin From the Outer Leaflet of a Mitochondrial Inner Membrane Mimic Restricts Opa1-Mediated Fusion. Front Mol Biosci 2022; 8:769135. [PMID: 35004847 PMCID: PMC8728091 DOI: 10.3389/fmolb.2021.769135] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 12/07/2021] [Indexed: 11/13/2022] Open
Abstract
Cardiolipin is a tetra-acylated di-phosphatidylglycerol lipid enriched in the matrix-facing (inner) leaflet of the mitochondrial inner membrane. Cardiolipin plays an important role in regulating mitochondria function and dynamics. Yet, the mechanisms connecting cardiolipin distribution and mitochondrial protein function remain indirect. In our previous work, we established an in vitro system reconstituting mitochondrial inner membrane fusion mediated by Opa1. We found that the long form of Opa1 (l-Opa1) works together with the proteolytically processed short form (s-Opa1) to mediate fast and efficient membrane fusion. Here, we extend our reconstitution system to generate supported lipid bilayers with asymmetric cardiolipin distribution. Using this system, we find the presence of cardiolipin on the inter-membrane space-facing (outer) leaflet is important for membrane tethering and fusion. We discuss how the presence of cardiolipin in this leaflet may influence protein and membrane properties, and future applications for this approach.
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Affiliation(s)
- Yifan Ge
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, United States.,Department of Genetics, Harvard Medical School, Boston, MA, United States
| | - Sivakumar Boopathy
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, United States.,Department of Genetics, Harvard Medical School, Boston, MA, United States
| | - Tran H Nguyen
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, United States.,Department of Genetics, Harvard Medical School, Boston, MA, United States
| | - Camila Makhlouta Lugo
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, United States.,Department of Genetics, Harvard Medical School, Boston, MA, United States
| | - Luke H Chao
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, United States.,Department of Genetics, Harvard Medical School, Boston, MA, United States
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9
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Canals D, Clarke CJ. Compartmentalization of Sphingolipid metabolism: Implications for signaling and therapy. Pharmacol Ther 2021; 232:108005. [PMID: 34582834 DOI: 10.1016/j.pharmthera.2021.108005] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 09/13/2021] [Accepted: 09/23/2021] [Indexed: 12/12/2022]
Abstract
Sphingolipids (SLs) are a family of bioactive lipids implicated in a variety of cellular processes, and whose levels are controlled by an interlinked network of enzymes. While the spatial distribution of SL metabolism throughout the cell has been understood for some time, the implications of this for SL signaling and biological outcomes have only recently begun to be fully explored. In this review, we outline the compartmentalization of SL metabolism and describe advances in tools for investigating and probing compartment-specific SL functions. We also briefly discuss the implications of SL compartmentalization for cell signaling and therapeutic approaches to targeting the SL network.
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Affiliation(s)
- Daniel Canals
- Department of Medicine and the Cancer Center, Stony Brook University, Stony Brook, NY, USA.
| | - Christopher J Clarke
- Department of Medicine and the Cancer Center, Stony Brook University, Stony Brook, NY, USA.
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10
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Ayee MAA, Levitan I. Lipoprotein-Induced Increases in Cholesterol and 7-Ketocholesterol Result in Opposite Molecular-Scale Biophysical Effects on Membrane Structure. Front Cardiovasc Med 2021; 8:715932. [PMID: 34336964 PMCID: PMC8322651 DOI: 10.3389/fcvm.2021.715932] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 06/21/2021] [Indexed: 11/13/2022] Open
Abstract
Under hypercholesterolemic conditions, exposure of cells to lipoproteins results in a subtle membrane increase in the levels of cholesterol and 7-ketocholesterol, as compared to normal conditions. The effect of these physiologically relevant concentration increases on multicomponent bilayer membranes was investigated using coarse-grained molecular dynamics simulations. Significant changes in the structural and dynamic properties of the bilayer membranes resulted from these subtle increases in sterol levels, with both sterol species inducing decreases in the lateral area and inhibiting lateral diffusion to varying extents. Cholesterol and 7-ketocholesterol, however, exhibited opposite effects on lipid packing and orientation. The results from this study indicate that the subtle increases in membrane sterol levels induced by exposure to lipoproteins result in molecular-scale biophysical perturbation of membrane structure.
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Affiliation(s)
- Manuela A A Ayee
- Department of Engineering, Dordt University, Sioux Center, IA, United States
| | - Irena Levitan
- Division of Pulmonary and Critical Care, Department of Medicine, University of Illinois at Chicago, Chicago, IL, United States
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11
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Tsai YT, Moore W, Kim H, Budin I. Bringing rafts to life: Lessons learned from lipid organization across diverse biological membranes. Chem Phys Lipids 2020; 233:104984. [PMID: 33203526 DOI: 10.1016/j.chemphyslip.2020.104984] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 09/13/2020] [Accepted: 09/28/2020] [Indexed: 10/23/2022]
Abstract
The ability of lipids to drive lateral organization is a remarkable feature of membranes and has been hypothesized to underlie the architecture of cells. Models for lipid rafts and related domains were originally based on the mammalian plasma membrane, but the nature of heterogeneity in this system is still not fully resolved. However, the concept of lipid-driven organization has been highly influential across biology, and has led to discoveries in organisms that feature a diversity of lipid chemistries and physiological needs. Here we review several emerging and instructive cases of membrane organization in non-mammalian systems. In bacteria, several types of membrane domains that act in metabolism and signaling have been elucidated. These widen our view of what constitutes a raft, but also introduce new questions about the relationship between organization and function. In yeast, observable membrane organization is found in both the plasma membrane and the vacuole. The latter serves as the best example of classic membrane phase partitioning in a living system to date, suggesting that internal organelles are important membranes to investigate across eukaryotes. Finally, we highlight plants as powerful model systems for complex membrane interactions in multicellular organisms. Plant membranes are organized by unique glycosphingolipids, supporting the importance of carbohydrate interactions in organizing lateral domains. These examples demonstrate that membrane organization is a potentially universal phenonenon in biology and argue for the continued broadening of lipid physical chemistry research into a wide range of systems.
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Affiliation(s)
- Yi-Ting Tsai
- Department of Chemistry & Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States
| | - William Moore
- Department of Chemistry & Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States
| | - Hyesoo Kim
- Department of Chemistry & Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States
| | - Itay Budin
- Department of Chemistry & Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States.
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12
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Vahedi A, Bigdelou P, Farnoud AM. Quantitative analysis of red blood cell membrane phospholipids and modulation of cell-macrophage interactions using cyclodextrins. Sci Rep 2020; 10:15111. [PMID: 32934292 PMCID: PMC7492248 DOI: 10.1038/s41598-020-72176-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Accepted: 08/21/2020] [Indexed: 01/27/2023] Open
Abstract
The plasma membrane of eukaryotic cells is asymmetric with respect to its phospholipid composition. Analysis of the lipid composition of the outer leaflet is important for understanding cell membrane biology in health and disease. Here, a method based on cyclodextrin-mediated lipid exchange to characterize the phospholipids in the outer leaflet of red blood cells (RBCs) is reported. Methyl-α-cyclodextrin, loaded with exogenous lipids, was used to extract phospholipids from the membrane outer leaflet, while delivering lipids to the cell to maintain cell membrane integrity. Thin layer chromatography and lipidomics demonstrated that the extracted lipids were from the membrane outer leaflet. Phosphatidylcholines (PC) and sphingomyelins (SM) were the most abundant phospholipids in the RBCs outer leaflet with PC 34:1 and SM 34:1 being the most abundant species. Fluorescence quenching confirmed the delivery of exogenous lipids to the cell outer leaflet. The developed lipid exchange method was then used to remove phosphatidylserine, a phagocyte recognition marker, from the outer leaflet of senescent RBCs. Senescent RBCs with reconstituted membranes were phagocytosed in significantly lower amounts compared to control cells, demonstrating the efficiency of the lipid exchange process and its application in modifying cell–cell interactions.
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Affiliation(s)
- Amid Vahedi
- Department of Chemical and Biomolecular Engineering, Ohio University, 161 Stocker Center, Athens, OH, 45701, USA
| | - Parnian Bigdelou
- Biomedical Engineering Program, Ohio University, Athens, OH, 45701, USA
| | - Amir M Farnoud
- Department of Chemical and Biomolecular Engineering, Ohio University, 161 Stocker Center, Athens, OH, 45701, USA. .,Biomedical Engineering Program, Ohio University, Athens, OH, 45701, USA.
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13
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Li G, Wang Q, Kakuda S, London E. Nanodomains can persist at physiologic temperature in plasma membrane vesicles and be modulated by altering cell lipids. J Lipid Res 2020; 61:758-766. [PMID: 31964764 DOI: 10.1194/jlr.ra119000565] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/06/2020] [Indexed: 01/04/2023] Open
Abstract
The formation and properties of liquid-ordered (Lo) lipid domains (rafts) in the plasma membrane are still poorly understood. This limits our ability to manipulate ordered lipid domain-dependent biological functions. Giant plasma membrane vesicles (GPMVs) undergo large-scale phase separations into coexisting Lo and liquid-disordered lipid domains. However, large-scale phase separation in GPMVs detected by light microscopy is observed only at low temperatures. Comparing Förster resonance energy transfer-detected versus light microscopy-detected domain formation, we found that nanodomains, domains of nanometer size, persist at temperatures up to 20°C higher than large-scale phases, up to physiologic temperature. The persistence of nanodomains at higher temperatures is consistent with previously reported theoretical calculations. To investigate the sensitivity of nanodomains to lipid composition, GPMVs were prepared from mammalian cells in which sterol, phospholipid, or sphingolipid composition in the plasma membrane outer leaflet had been altered by cyclodextrin-catalyzed lipid exchange. Lipid substitutions that stabilize or destabilize ordered domain formation in artificial lipid vesicles had a similar effect on the thermal stability of nanodomains and large-scale phase separation in GPMVs, with nanodomains persisting at higher temperatures than large-scale phases for a wide range of lipid compositions. This indicates that it is likely that plasma membrane nanodomains can form under physiologic conditions more readily than large-scale phase separation. We also conclude that membrane lipid substitutions carried out in intact cells are able to modulate the propensity of plasma membranes to form ordered domains. This implies lipid substitutions can be used to alter biological processes dependent upon ordered domains.
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Affiliation(s)
- Guangtao Li
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215
| | - Qing Wang
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215
| | - Shinako Kakuda
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215
| | - Erwin London
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215. mailto:
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