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Griffo A, Sparn C, Lolicato F, Nolle F, Khangholi N, Seemann R, Fleury JB, Brinkmann M, Nickel W, Hähl H. Mechanics of biomimetic free-standing lipid membranes: insights into the elasticity of complex lipid compositions. RSC Adv 2024; 14:13044-13052. [PMID: 38655466 PMCID: PMC11034475 DOI: 10.1039/d4ra00738g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 04/08/2024] [Indexed: 04/26/2024] Open
Abstract
The creation of free-standing lipid membranes has been so far of remarkable interest to investigate processes occurring in the cell membrane since its unsupported part enables studies in which it is important to maintain cell-like physicochemical properties of the lipid bilayer, that nonetheless depend on its molecular composition. In this study, we prepare pore-spanning membranes that mimic the composition of plasma membranes and perform force spectroscopy indentation measurements to unravel mechanistic insights depending on lipid composition. We show that this approach is highly effective for studying the mechanical properties of such membranes. Furthermore, we identify a direct influence of cholesterol and sphingomyelin on the elasticity of the bilayer and adhesion between the two leaflets. Eventually, we explore the possibilities of imaging in the unsupported membrane regions. For this purpose, we investigate the adsorption and movement of a peripheral protein, the fibroblast growth factor 2, on the complex membrane.
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Affiliation(s)
- Alessandra Griffo
- Center for Biophysics, Experimental Physics, Saarland University Saarbrücken Germany
- Department of Experimental Physics, Saarland University Saarbrücken Germany
- Biophysical Engineering Group, Max Planck Institute for Medical Research Heidelberg Germany
| | - Carola Sparn
- Heidelberg University Biochemistry Center Heidelberg Germany
| | - Fabio Lolicato
- Heidelberg University Biochemistry Center Heidelberg Germany
| | - Friederike Nolle
- Center for Biophysics, Experimental Physics, Saarland University Saarbrücken Germany
- Department of Experimental Physics, Saarland University Saarbrücken Germany
| | - Navid Khangholi
- Center for Biophysics, Experimental Physics, Saarland University Saarbrücken Germany
- Department of Experimental Physics, Saarland University Saarbrücken Germany
| | - Ralf Seemann
- Center for Biophysics, Experimental Physics, Saarland University Saarbrücken Germany
| | - Jean-Baptiste Fleury
- Center for Biophysics, Experimental Physics, Saarland University Saarbrücken Germany
- Department of Experimental Physics, Saarland University Saarbrücken Germany
| | - Martin Brinkmann
- Department of Experimental Physics, Saarland University Saarbrücken Germany
| | - Walter Nickel
- Heidelberg University Biochemistry Center Heidelberg Germany
| | - Hendrik Hähl
- Center for Biophysics, Experimental Physics, Saarland University Saarbrücken Germany
- Department of Experimental Physics, Saarland University Saarbrücken Germany
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Krmic M, Perez E, Scollan P, Ivanchenko K, Gamez Hernandez A, Giancaspro J, Rosario J, Ceja-Vega J, Gudyka J, Porteus R, Lee S. Aspirin Interacts with Cholesterol-Containing Membranes in a pH-Dependent Manner. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:16444-16456. [PMID: 37939382 PMCID: PMC10666536 DOI: 10.1021/acs.langmuir.3c02242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 10/20/2023] [Accepted: 10/23/2023] [Indexed: 11/10/2023]
Abstract
Aspirin has been used for broad therapeutic treatment, including secondary prevention of cardiovascular disease associated with increased cholesterol levels. Aspirin and other nonsteroidal anti-inflammatory drugs have been shown to interact with lipid membranes and change their biophysical properties. In this study, mixed lipid model bilayers made from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) or 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) comprising varying concentrations of cholesterol (10:1, 4:1, and 1:1 mole ratio of lipid:chol), prepared by the droplet interface bilayer method, were used to examine the effects of aspirin at various pH on transbilayer water permeability. The presence of aspirin increases the water permeability of POPC bilayers in a concentration-dependent manner, with a greater magnitude of increase at pH 3 compared to pH 7. In the presence of cholesterol, aspirin is similarly shown to increase water permeability; however, the extent of the increase depends on both the concentration of cholesterol and the pH, with the least pronounced enhancement in water permeability at high cholesterol levels at pH 7. A fusion of data from differential scanning calorimetry, confocal Raman microspectrophotometry, and interfacial tensiometric measurements demonstrates that aspirin can promote significant thermal, structural, and interfacial property perturbations in the mixed-lipid POPC or DOPC membranes containing cholesterol, indicating a disordering effect on the lipid membranes. Our findings suggest that aspirin fluidizes phosphocholine membranes in both cholesterol-free and cholesterol-enriched states and that the overall effect is greater when aspirin is in a neutral state. These results confer a deeper comprehension of the divergent effects of aspirin on biological membranes having heterogeneous compositions, under varying physiological pH and different cholesterol compositions, with implications for a better understanding of the gastrointestinal toxicity induced by the long term use of this important nonsteroidal anti-inflammatory molecule.
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Affiliation(s)
- Michael Krmic
- Department of Chemistry and Biochemistry, Iona University, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Escarlin Perez
- Department of Chemistry and Biochemistry, Iona University, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Patrick Scollan
- Department of Chemistry and Biochemistry, Iona University, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Katherine Ivanchenko
- Department of Chemistry and Biochemistry, Iona University, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Alondra Gamez Hernandez
- Department of Chemistry and Biochemistry, Iona University, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Joseph Giancaspro
- Department of Chemistry and Biochemistry, Iona University, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Juan Rosario
- Department of Chemistry and Biochemistry, Iona University, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Jasmin Ceja-Vega
- Department of Chemistry and Biochemistry, Iona University, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Jamie Gudyka
- Department of Chemistry and Biochemistry, Iona University, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Riley Porteus
- Department of Chemistry and Biochemistry, Iona University, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Sunghee Lee
- Department of Chemistry and Biochemistry, Iona University, 715 North Avenue, New Rochelle, New York 10801, United States
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Lolicato F, Saleppico R, Griffo A, Meyer A, Scollo F, Pokrandt B, Müller HM, Ewers H, Hähl H, Fleury JB, Seemann R, Hof M, Brügger B, Jacobs K, Vattulainen I, Nickel W. Cholesterol promotes clustering of PI(4,5)P2 driving unconventional secretion of FGF2. J Biophys Biochem Cytol 2022; 221:213511. [PMID: 36173379 PMCID: PMC9526255 DOI: 10.1083/jcb.202106123] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/22/2022] [Accepted: 08/30/2022] [Indexed: 11/22/2022] Open
Abstract
FGF2 is a cell survival factor involved in tumor-induced angiogenesis that is secreted through an unconventional secretory pathway based upon direct protein translocation across the plasma membrane. Here, we demonstrate that both PI(4,5)P2-dependent FGF2 recruitment at the inner plasma membrane leaflet and FGF2 membrane translocation into the extracellular space are positively modulated by cholesterol in living cells. We further revealed cholesterol to enhance FGF2 binding to PI(4,5)P2-containing lipid bilayers. Based on extensive atomistic molecular dynamics (MD) simulations and membrane tension experiments, we proposed cholesterol to modulate FGF2 binding to PI(4,5)P2 by (i) increasing head group visibility of PI(4,5)P2 on the membrane surface, (ii) increasing avidity by cholesterol-induced clustering of PI(4,5)P2 molecules triggering FGF2 oligomerization, and (iii) increasing membrane tension facilitating the formation of lipidic membrane pores. Our findings have general implications for phosphoinositide-dependent protein recruitment to membranes and explain the highly selective targeting of FGF2 toward the plasma membrane, the subcellular site of FGF2 membrane translocation during unconventional secretion of FGF2.
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Affiliation(s)
- Fabio Lolicato
- Heidelberg University Biochemistry Center, Heidelberg, Germany.,Department of Physics, University of Helsinki, Helsinki, Finland
| | | | - Alessandra Griffo
- Department of Experimental Physics, Saarland University, Saarbrücken, Germany.,Biophysical Engineering Group, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Annalena Meyer
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Federica Scollo
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Bianca Pokrandt
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | | | - Helge Ewers
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Hendrik Hähl
- Department of Experimental Physics, Saarland University, Saarbrücken, Germany
| | | | - Ralf Seemann
- Department of Experimental Physics, Saarland University, Saarbrücken, Germany
| | - Martin Hof
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Britta Brügger
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Karin Jacobs
- Department of Experimental Physics, Saarland University, Saarbrücken, Germany.,Max Planck School Matter to Life, Heidelberg, Germany
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg, Germany
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Puza S, Caesar S, Poojari C, Jung M, Seemann R, Hub JS, Schrul B, Fleury JB. Lipid Droplets Embedded in a Model Cell Membrane Create a Phospholipid Diffusion Barrier. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2106524. [PMID: 35072348 DOI: 10.1002/smll.202106524] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/09/2021] [Indexed: 06/14/2023]
Abstract
Lipid droplets (LDs) are ubiquitous, cytoplasmic fat storage organelles that originate from the endoplasmic reticulum (ER) membrane. They are composed of a core of neutral lipids surrounded by a phospholipid monolayer. Proteins embedded into this monolayer membrane adopt a monotopic topology and are crucial for regulated lipid storage and consumption. A key question is, which collective properties of protein-intrinsic and lipid-mediated features determine spatio-temporal protein partitioning between phospholipid bilayer and LD monolayer membranes. To address this question, a freestanding phospholipid bilayer with physiological lipidic composition is produced using microfluidics and micrometer-sized LDs are dispersed around the bilayer that spontaneously insert into the bilayer. Using confocal microscopy, the 3D geometry of the reconstituted LDs is determined with high spatial resolution. The micrometer-sized bilayer-embedded LDs present a characteristic lens shape that obeys predictions from equilibrium wetting theory. Fluorescence recovery after photobleaching measurements reveals the existence of a phospholipid diffusion barrier at the monolayer-bilayer interface. Coarse-grained molecular dynamics simulation reveals lipid specific density distributions along the pore rim, which may rationalize the diffusion barrier. The lipid diffusion barrier between the LD covering monolayer and the bilayer may be a key phenomenon influencing protein partitioning between the ER membrane and LDs in living cells.
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Affiliation(s)
- Sevde Puza
- Saarland University, Experimental Physics and Center for Biophysics (ZBP), Saarland University, 66123, Saarbrücken, Germany
| | - Stefanie Caesar
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling (PZMS), Faculty of Medicine, Saarland University, 66421, Homburg, Germany
| | - Chetan Poojari
- Saarland University, Theoretical Physics and Center for Biophysics (ZBP), Saarland University, 66123, Saarbrücken, Germany
| | - Michael Jung
- Saarland University, Experimental Physics and Center for Biophysics (ZBP), Saarland University, 66123, Saarbrücken, Germany
| | - Ralf Seemann
- Saarland University, Experimental Physics and Center for Biophysics (ZBP), Saarland University, 66123, Saarbrücken, Germany
| | - Jochen S Hub
- Saarland University, Theoretical Physics and Center for Biophysics (ZBP), Saarland University, 66123, Saarbrücken, Germany
| | - Bianca Schrul
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling (PZMS), Faculty of Medicine, Saarland University, 66421, Homburg, Germany
| | - Jean-Baptiste Fleury
- Saarland University, Experimental Physics and Center for Biophysics (ZBP), Saarland University, 66123, Saarbrücken, Germany
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Photoactivation of Cell-Free Expressed Archaerhodopsin-3 in a Model Cell Membrane. Int J Mol Sci 2021; 22:ijms222111981. [PMID: 34769410 PMCID: PMC8584582 DOI: 10.3390/ijms222111981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 11/27/2022] Open
Abstract
Transmembrane receptor proteins are located in the plasma membranes of biological cells where they exert important functions. Archaerhodopsin (Arch) proteins belong to a class of transmembrane receptor proteins called photoreceptors that react to light. Although the light sensitivity of proteins has been intensely investigated in recent decades, the electrophysiological properties of pore-forming Archaerhodopsin (Arch), as studied in vitro, have remained largely unknown. Here, we formed unsupported bilayers between two channels of a microfluidic chip which enabled the simultaneous optical and electrical assessment of the bilayer in real time. Using a cell-free expression system, we recombinantly produced a GFP (green fluorescent protein) labelled as a variant of Arch-3. The label enabled us to follow the synthesis of Arch-3 and its incorporation into the bilayer by fluorescence microscopy when excited by blue light. Applying a green laser for excitation, we studied the electrophysiological properties of Arch-3 in the bilayer. The current signal obtained during excitation revealed distinct steps upwards and downwards, which we interpreted as the opening or closing of Arch-3 pores. From these steps, we estimated the pore radius to be 0.3 nm. In the cell-free extract, proteins can be modified simply by changing the DNA. In the future, this will enable us to study the photoelectrical properties of modified transmembrane protein constructs with ease. Our work, thus, represents a first step in studying signaling cascades in conjunction with coupled receptor proteins.
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Wood M, Morales M, Miller E, Braziel S, Giancaspro J, Scollan P, Rosario J, Gayapa A, Krmic M, Lee S. Ibuprofen and the Phosphatidylcholine Bilayer: Membrane Water Permeability in the Presence and Absence of Cholesterol. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:4468-4480. [PMID: 33826350 DOI: 10.1021/acs.langmuir.0c03638] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The interactions between drugs and cell membranes can modulate the structural and physical properties of membranes. The resultant perturbations of the membrane integrity may affect the conformation of the proteins inserted within the membrane, disturbing the membrane-hosted biological functions. In this study, the droplet interface bilayer (DIB), a model cell membrane, is used to examine the effects of ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID), on transbilayer water permeability, which is a fundamental membrane biophysical property. Our results indicate that the presence of neutral ibuprofen (pH 3) increases the water permeability of the lipid membranes composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). When cholesterol is present with the DOPC, however, the water permeability is not influenced by addition of ibuprofen, regardless of the cholesterol content in DOPC. Given the fact that cholesterol is generally considered to impact packing in the hydrocarbon chain regions, our findings suggest that a potential competition between opposing effects of ibuprofen molecules and cholesterol on the hydrocarbon core environment of the phospholipid assembly may influence the overall water transport phenomena. Results from confocal Raman microspectroscopy and interfacial tensiometry show that ibuprofen molecules induce substantial structural and dynamic changes in the DOPC lipid bilayer. These results, demonstrating that the presence of ibuprofen increases the water permeability of pure DOPC but not that of DOPC-cholesterol mixtures, provide insight into the differential effect of a representative NSAID on heterogeneous biological membranes, depending upon the local composition and structure, results which will signal increased understanding of the gastrointestinal damage and toxicity induced by these molecules.
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Affiliation(s)
- Megan Wood
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Michael Morales
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Elizabeth Miller
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Samuel Braziel
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Joseph Giancaspro
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Patrick Scollan
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Juan Rosario
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Alyssa Gayapa
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Michael Krmic
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Sunghee Lee
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
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Tawfik H, Puza S, Seemann R, Fleury JB. Transport Properties of Gramicidin A Ion Channel in a Free-Standing Lipid Bilayer Filled With Oil Inclusions. Front Cell Dev Biol 2020; 8:531229. [PMID: 33015051 PMCID: PMC7498540 DOI: 10.3389/fcell.2020.531229] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 08/14/2020] [Indexed: 11/13/2022] Open
Abstract
Ion channels are key proteins in mammalian cell membranes. They have a central role in the physiology of excitable cells such as neurons, muscle, and heart cells. They also play a crucial role in kidney physiology. The gramicidin ion channel is one of the most studied ion channels, in particular it was intensively employed to investigate the lipid–protein interactions in model cell membranes. For example, even though the sequence of gramicidin is extremely hydrophobic, its motion is impaired in membrane bilayer, i.e., it does not rapidly flip to the other membrane leaflet, and low channel activity were observed when gramicidin is added asymmetrically to only one leaflet of a model cell membrane. In this article, we study the transport properties of gramicidin channel in a heterogeneous model membrane. Using microfluidics, we are forming freestanding bilayers as model cell membranes including heterogeneous domains that are created by oil inclusions. The presence of oil inclusions is then demonstrated by measuring the bilayer capacity via a patch-clamp amplifier and fluorescent confocal inspection. Based on electrophysiological and optical measurements Gramicidin A (gA) ion channels are dispersed into the buffer phases on both side of the formed lipid bilayer and insert spontaneously into the bilayer upon formation. The presence of functional Gramicidin A is then demonstrated by measuring conductivity signals. Based on electrophysiological and optical measurements, we explore the consequence of the presence of these oil inclusions on the functionality of incorporated gA ion channels. For low oil concentration, we measure a decrease of gA transport properties due to the reduction of the bilayer tension. For large oil concentration, we measure a saturation of gA transport properties due to an increase of the bilayer thickness.
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Affiliation(s)
- Harvey Tawfik
- Experimental Physics and Center for Biophysics, Universität des Saarlandes, Saarbrücken, Germany
| | - Sevde Puza
- Experimental Physics and Center for Biophysics, Universität des Saarlandes, Saarbrücken, Germany
| | - Ralf Seemann
- Experimental Physics and Center for Biophysics, Universität des Saarlandes, Saarbrücken, Germany
| | - Jean-Baptiste Fleury
- Experimental Physics and Center for Biophysics, Universität des Saarlandes, Saarbrücken, Germany
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