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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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Plasma membrane effects of sphingolipid-synthesis inhibition by myriocin in CHO cells: a biophysical and lipidomic study. Sci Rep 2022; 12:955. [PMID: 35046440 PMCID: PMC8770663 DOI: 10.1038/s41598-021-04648-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 11/08/2021] [Indexed: 11/08/2022] Open
Abstract
Suppression of a specific gene effect can be achieved by genetic as well as chemical methods. Each approach may hide unexpected drawbacks, usually in the form of side effects. In the present study, the specific inhibitor myriocin was used to block serine palmitoyltransferase (SPT), the first enzyme in the sphingolipid synthetic pathway, in CHO cells. The subsequent biophysical changes in plasma membranes were measured and compared with results obtained with a genetically modified CHO cell line containing a defective SPT (the LY-B cell line). Similar effects were observed with both approaches: sphingomyelin values were markedly decreased in myriocin-treated CHO cells and, in consequence, their membrane molecular order (measured as laurdan general polarization) and mechanical resistance (AFM-measured breakthrough force values) became lower than in the native, non-treated cells. Cells treated with myriocin reacted homeostatically to maintain membrane order, synthesizing more fully saturated and less polyunsaturated GPL than the non-treated ones, although they achieved it only partially, their plasma membranes remaining slightly more fluid and more penetrable than those from the control cells. The good agreement between results obtained with very different tools, such as genetically modified and chemically treated cells, reinforces the use of both methods and demonstrates that both are adequate for their intended use, i.e. the complete and specific inhibition of sphingolipid synthesis in CHO cells, without apparent unexpected effects.
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Monasterio BG, Jiménez-Rojo N, García-Arribas AB, Riezman H, Goñi FM, Alonso A. CHO/LY-B cell growth under limiting sphingolipid supply: Correlation between lipid composition and biophysical properties of sphingolipid-restricted cell membranes. FASEB J 2021; 35:e21657. [PMID: 34010474 DOI: 10.1096/fj.202001879rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 04/09/2021] [Accepted: 04/26/2021] [Indexed: 11/11/2022]
Abstract
Sphingolipids (SL) are ubiquitous in mammalian cell membranes, yet there is little data on the behavior of cells under SL-restriction conditions. LY-B cells derive from a CHO linein whichserine palmitoyl transferase (SPT), thus de novo SL synthesis, is suppressed, while maintaining the capacity of taking up and metabolizing exogenous sphingoid bases from the culture medium. In this study, LY-B cells were adapted to grow in a fetal bovine serum (FBS)-deficient medium to avoid external uptake of lipids. The lowest FBS concentration that allowed LY-B cell growth, though at a slow rate, under our conditions was 0.04%, that is, 250-fold less than the standard (10%) concentration. Cells grown under limiting SL concentrations remained viable for at least 72 hours. Enriching with sphingomyelin the SL-deficient medium allowed the recovery of growth rates analogous to those of control LY-B cells. Studies including whole cells, plasma membrane preparations, and derived lipid vesicles were carried out. Laurdan fluorescence was recorded to measure membrane molecular order, showing a significant decrease in the rigidity of LY-B cells, not only in plasma membrane but also in whole cell lipid extract, as a result of SL limitation in the growth medium. Plasma membrane preparations and whole cell lipid extracts were also studied using atomic force microscopy in the force spectroscopy mode. Force measurements demonstrated that lower breakthrough forces were required to penetrate samples obtained from SL-poor LY-B cells than those obtained from control cells. Mass-spectroscopic analysis was also a helpful tool to understand the rearrangement undergone by the LY-B cell lipid metabolism. The most abundant SL in LY-B cells, sphingomyelin, decreased by about 85% as a result of SL limitation in the medium, the bioactive lipid ceramide and the ganglioside precursor hexosylceramide decreased similarly, together with cholesterol. Quantitative SL analysis showed that a 250-fold reduction in sphingolipid supply to LY-B cells led only to a sixfold decrease in membrane sphingolipids, underlining the resistance to changes in composition of these cells. Plasma membrane compositions exhibited similar changes, at least qualitatively, as the whole cells with SL restriction. A linear correlation was observed between the sphingomyelin concentration in the membranes, the degree of lipid order as measured by laurdan fluorescence, and membrane breakthrough forces assessed by atomic force microscopy. Smaller, though significant, changes were also detected in glycerophospholipids under SL-restriction conditions.
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Affiliation(s)
- Bingen G Monasterio
- Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Leioa, Spain.,Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
| | - Noemi Jiménez-Rojo
- NCCR Chemical Biology, Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Aritz B García-Arribas
- Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Leioa, Spain.,Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
| | - Howard Riezman
- NCCR Chemical Biology, Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Félix M Goñi
- Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Leioa, Spain.,Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
| | - Alicia Alonso
- Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Leioa, Spain.,Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
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Dong S, Tang X, Wang J, Zhang Z, Chen J, Lin Y, Xie S, Wang Z, Yang H. Self-assembly of lipid rafts revealed by fluorescence correlation spectroscopy in living breast cancer cells. JOURNAL OF BIOPHOTONICS 2020; 13:e201900214. [PMID: 31675171 DOI: 10.1002/jbio.201900214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 10/29/2019] [Accepted: 10/30/2019] [Indexed: 06/10/2023]
Abstract
Lipids and proteins in the plasma membrane are laterally heterogeneous and formalised as lipid rafts featuring unique biophysical properties. However, the self-assembly mechanism of lipid raft cannot be revealed even its physical properties and components were determined in specific physiological processes. In this study, two-photon generalised polarisation imaging and fluorescence correlation spectroscopy were used to study the fusion of lipid rafts through the membrane phase and the lateral diffusion of lipids in living breast cancer cells. A self-assembly model of lipid rafts associated with lipid diffusion and membrane phase was proposed to demonstrate the lipid sorting ability of lipid rafts in the plasma membrane. The results showed that the increased proportion of slow subdiffusion of GM1 -binding cholera toxin B-subunit (CT-B) was accompanied with an increased liquid-ordered domain during the β-estradiol-induced fusion of lipid rafts. And slow subdiffusion of CT-B was vanished with the depletion of lipid rafts. Whereas the dialkylindocarbocyanine (DiIC18 ) diffusion was not specifically regulated by lipid rafts. This study will open up a new insight for uncovering the self-assembly of lipid rafts in specific pathophysiological processes.
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Affiliation(s)
- Shiqing Dong
- Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, China
| | - Xiaoqiong Tang
- Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, China
| | - Jiao Wang
- Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, China
| | - Zhenghong Zhang
- Provincial Key Laboratory for Developmental Biology and Neurosciences, College of Life Sciences, Fujian Normal University, Fuzhou, China
| | - Jianling Chen
- Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, China
| | - Yao Lin
- Provincial Key Laboratory for Developmental Biology and Neurosciences, College of Life Sciences, Fujian Normal University, Fuzhou, China
| | - Shusen Xie
- Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, China
| | - Zhengchao Wang
- Provincial Key Laboratory for Developmental Biology and Neurosciences, College of Life Sciences, Fujian Normal University, Fuzhou, China
| | - Hongqin Yang
- Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, China
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Bag N, Holowka DA, Baird BA. Imaging FCS delineates subtle heterogeneity in plasma membranes of resting mast cells. Mol Biol Cell 2020; 31:709-723. [PMID: 31895009 PMCID: PMC7202073 DOI: 10.1091/mbc.e19-10-0559] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
A myriad of transient, nanoscopic lipid- and protein-based interactions confer a steady-state organization of the plasma membrane in resting cells that is poised to orchestrate assembly of key signaling components upon reception of an extracellular stimulus. Although difficult to observe directly in live cells, these subtle interactions can be discerned by their impact on the diffusion of membrane constituents. Here, we quantified the diffusion properties of a panel of structurally distinct lipid, lipid-anchored, and transmembrane (TM) probes in RBL mast cells by imaging fluorescence correlation spectroscopy (ImFCS). We developed a statistical analysis of data combined from many pixels over multiple cells to characterize differences in diffusion coefficients as small as 10%, which reflect differences in underlying interactions. We found that the distinctive diffusion properties of lipid probes can be explained by their dynamic partitioning into Lo-like proteolipid nanodomains, which encompass a major fraction of the membrane and whose physical properties are influenced by actin polymerization. Effects on diffusion of functional protein modules in both lipid-anchored and TM probes reflect additional complexity in steady state membrane organization. The contrast we observe between different probes diffusing through the same membrane milieu represents the dynamic resting steady state, which serves as a baseline for monitoring plasma membrane remodeling that occurs upon stimulation.
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Affiliation(s)
- Nirmalya Bag
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
| | - David A Holowka
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
| | - Barbara A Baird
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
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Devanand T, Krishnaswamy S, Vemparala S. Interdigitation of Lipids Induced by Membrane–Active Proteins. J Membr Biol 2019; 252:331-342. [DOI: 10.1007/s00232-019-00072-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 05/29/2019] [Indexed: 12/18/2022]
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Pyrshev KA, Yesylevskyy SO, Demchenko AP. Double-exponential kinetics of binding and redistribution of the fluorescent dyes in cell membranes witness for the existence of lipid microdomains. Biochem Biophys Res Commun 2019; 508:1139-1144. [PMID: 30554653 DOI: 10.1016/j.bbrc.2018.12.054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Accepted: 12/06/2018] [Indexed: 11/26/2022]
Abstract
New technique of detecting lateral heterogeneity of the plasma membrane of living cells by means of membrane-binding fluorescent dyes is proposed. The kinetics of dye incorporation into the membrane or its lateral diffusion inside the membrane is measured and decomposed into exponential components by means of the Maximum Entropy Method. Two distinct exponential components are obtained consistently in all cases for several fluorescent dyes, two different cell lines and in different types of experiments including spectroscopy, flow cytometry and fluorescence recovery after photobleaching. These components are attributed to the liquid-ordered and disordered phases in the plasma membrane of studied cells in their dynamic equilibrium.
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Affiliation(s)
- Kyrylo A Pyrshev
- Laboratory of Nanobiotechnologies, O.V. Palladin Institute of Biochemistry of the NAS of Ukraine, Leontovicha Str. 9, Kyiv, 01030, Ukraine; Department of Physics of Biological Systems, Institute of Physics of the National Academy of Sciences of Ukraine, Nauky Ave. 46, Kyiv, 03028, Ukraine.
| | - Semen O Yesylevskyy
- Department of Physics of Biological Systems, Institute of Physics of the National Academy of Sciences of Ukraine, Nauky Ave. 46, Kyiv, 03028, Ukraine; Laboratoire Chrono Environnement UMR CNRS 6249, Université de Bourgogne Franche-Comté, 16 Route de Gray, 25030, Besançon Cedex, France
| | - Alexander P Demchenko
- Laboratory of Nanobiotechnologies, O.V. Palladin Institute of Biochemistry of the NAS of Ukraine, Leontovicha Str. 9, Kyiv, 01030, Ukraine
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Ma Y, Benda A, Kwiatek J, Owen DM, Gaus K. Time-Resolved Laurdan Fluorescence Reveals Insights into Membrane Viscosity and Hydration Levels. Biophys J 2018; 115:1498-1508. [PMID: 30269886 PMCID: PMC6257870 DOI: 10.1016/j.bpj.2018.08.041] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 06/27/2018] [Accepted: 08/27/2018] [Indexed: 11/24/2022] Open
Abstract
Membrane viscosity and hydration levels characterize the biophysical properties of biological membranes and are reflected in the rate and extent of solvent relaxation, respectively, of environmentally sensitive fluorophores such as Laurdan. Here, we first developed a method for a time-resolved general polarization (GP) analysis with fluorescence-lifetime imaging microscopy that captures both the extent and rate of Laurdan solvent relaxation. We then conducted time-resolved GP measurements with Laurdan-stained model membranes and cell membranes. These measurements revealed that cholesterol levels in lipid vesicles altered membrane hydration and viscosity, whereas curvature had little effect on either parameter. We also applied the method to the plasma membrane of live cells using a supercritical angle fluorescence objective, to our knowledge the first time fluorescence-lifetime imaging microscopy images were generated with supercritical angle fluorescence. Here, we found that local variations in membrane cholesterol most likely account for the heterogeneity of Laurdan lifetime in plasma membrane. In conclusion, time-resolved GP measurements provide additional insights into the biophysical properties of membranes.
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Affiliation(s)
- Yuanqing Ma
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, New South Wales, Australia
| | - Aleš Benda
- Biomedical Imaging Facility, Lowy Cancer Research Centre, University of New South Wales, Sydney, New South Wales, Australia
| | - Joanna Kwiatek
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, New South Wales, Australia
| | - Dylan M Owen
- Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Katharina Gaus
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, New South Wales, Australia.
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