1
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Lira RB, Dillingh LS, Schuringa JJ, Yahioglu G, Suhling K, Roos WH. Fluorescence lifetime imaging microscopy of flexible and rigid dyes probes the biophysical properties of synthetic and biological membranes. Biophys J 2024:S0006-3495(24)00313-8. [PMID: 38702882 DOI: 10.1016/j.bpj.2024.04.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 03/22/2024] [Accepted: 04/30/2024] [Indexed: 05/06/2024] Open
Abstract
Sensing of the biophysical properties of membranes using molecular reporters has recently regained widespread attention. This was elicited by the development of new probes of exquisite optical properties and increased performance, combined with developments in fluorescence detection. Here, we report on fluorescence lifetime imaging of various rigid and flexible fluorescent dyes to probe the biophysical properties of synthetic and biological membranes at steady state as well as upon the action of external membrane-modifying agents. We tested the solvatochromic dyes Nile red and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine-N-(7-nitro-2-1,3-benzoxadiazol-4-yl) (ammonium salt) (NBD), the viscosity sensor Bodipy C12, the flipper dye FliptR, as well as the dyes 3,3'-dioctadecyloxacarbocyanine perchlorate (DiO), Bodipy C16, lissamine-rhodamine, and Atto647, which are dyes with no previous reported environmental sensitivity. The performance of the fluorescent probes, many of which are commercially available, was benchmarked with well-known environmental reporters, with Nile red and Bodipy C12 being specific reporters of medium hydration and viscosity, respectively. We show that some widely used ordinary dyes with no previous report of sensing capabilities can exhibit competing performance compared to highly sensitive commercially available or custom-based solvatochromic dyes, molecular rotors, or flipper in a wide range of biophysics experiments. Compared to other methods, fluorescence lifetime imaging is a minimally invasive and nondestructive method with optical resolution. It enables biophysical mapping at steady state or assessment of the changes induced by membrane-active molecules at subcellular level in both synthetic and biological membranes when intensity measurements fail to do so. The results have important consequences for the specific choice of the sensor and take into consideration factors such as probe sensitivity, response to environmental changes, ease and speed of data analysis, and the probe's intracellular distribution, as well as potential side effects induced by labeling and imaging.
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Affiliation(s)
- Rafael B Lira
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Groningen, the Netherlands.
| | - Laura S Dillingh
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Groningen, the Netherlands; Department of Hematology, Universitair Medisch Centrum Groningen & Rijksuniversiteit Groningen, Groningen, the Netherlands
| | - Jan-Jacob Schuringa
- Department of Hematology, Universitair Medisch Centrum Groningen & Rijksuniversiteit Groningen, Groningen, the Netherlands
| | | | - Klaus Suhling
- Department of Physics, King's College London, Strand, London, UK.
| | - Wouter H Roos
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Groningen, the Netherlands
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2
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Erazo-Oliveras A, Muñoz-Vega M, Salinas ML, Wang X, Chapkin RS. Dysregulation of cellular membrane homeostasis as a crucial modulator of cancer risk. FEBS J 2024; 291:1299-1352. [PMID: 36282100 PMCID: PMC10126207 DOI: 10.1111/febs.16665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 09/09/2022] [Accepted: 10/24/2022] [Indexed: 11/07/2022]
Abstract
Cellular membranes serve as an epicentre combining extracellular and cytosolic components with membranous effectors, which together support numerous fundamental cellular signalling pathways that mediate biological responses. To execute their functions, membrane proteins, lipids and carbohydrates arrange, in a highly coordinated manner, into well-defined assemblies displaying diverse biological and biophysical characteristics that modulate several signalling events. The loss of membrane homeostasis can trigger oncogenic signalling. More recently, it has been documented that select membrane active dietaries (MADs) can reshape biological membranes and subsequently decrease cancer risk. In this review, we emphasize the significance of membrane domain structure, organization and their signalling functionalities as well as how loss of membrane homeostasis can steer aberrant signalling. Moreover, we describe in detail the complexities associated with the examination of these membrane domains and their association with cancer. Finally, we summarize the current literature on MADs and their effects on cellular membranes, including various mechanisms of dietary chemoprevention/interception and the functional links between nutritional bioactives, membrane homeostasis and cancer biology.
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Affiliation(s)
- Alfredo Erazo-Oliveras
- Program in Integrative Nutrition and Complex Diseases; Texas A&M University; College Station, Texas, 77843; USA
- Department of Nutrition; Texas A&M University; College Station, Texas, 77843; USA
| | - Mónica Muñoz-Vega
- Program in Integrative Nutrition and Complex Diseases; Texas A&M University; College Station, Texas, 77843; USA
- Department of Nutrition; Texas A&M University; College Station, Texas, 77843; USA
| | - Michael L. Salinas
- Program in Integrative Nutrition and Complex Diseases; Texas A&M University; College Station, Texas, 77843; USA
- Department of Nutrition; Texas A&M University; College Station, Texas, 77843; USA
| | - Xiaoli Wang
- Program in Integrative Nutrition and Complex Diseases; Texas A&M University; College Station, Texas, 77843; USA
- Department of Nutrition; Texas A&M University; College Station, Texas, 77843; USA
| | - Robert S. Chapkin
- Program in Integrative Nutrition and Complex Diseases; Texas A&M University; College Station, Texas, 77843; USA
- Department of Nutrition; Texas A&M University; College Station, Texas, 77843; USA
- Center for Environmental Health Research; Texas A&M University; College Station, Texas, 77843; USA
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3
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Singh G, George G, Raja SO, Kandaswamy P, Kumar M, Thutupalli S, Laxman S, Gulyani A. A molecular rotor FLIM probe reveals dynamic coupling between mitochondrial inner membrane fluidity and cellular respiration. Proc Natl Acad Sci U S A 2023; 120:e2213241120. [PMID: 37276406 PMCID: PMC10268597 DOI: 10.1073/pnas.2213241120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 04/13/2023] [Indexed: 06/07/2023] Open
Abstract
The inner mitochondrial membrane (IMM), housing components of the electron transport chain (ETC), is the site for respiration. The ETC relies on mobile carriers; therefore, it has long been argued that the fluidity of the densely packed IMM can potentially influence ETC flux and cell physiology. However, it is unclear if cells temporally modulate IMM fluidity upon metabolic or other stimulation. Using a photostable, red-shifted, cell-permeable molecular-rotor, Mitorotor-1, we present a multiplexed approach for quantitatively mapping IMM fluidity in living cells. This reveals IMM fluidity to be linked to cellular-respiration and responsive to stimuli. Multiple approaches combining in vitro experiments and live-cell fluorescence (FLIM) lifetime imaging microscopy (FLIM) show Mitorotor-1 to robustly report IMM 'microviscosity'/fluidity through changes in molecular free volume. Interestingly, external osmotic stimuli cause controlled swelling/compaction of mitochondria, thereby revealing a graded Mitorotor-1 response to IMM microviscosity. Lateral diffusion measurements of IMM correlate with microviscosity reported via Mitorotor-1 FLIM-lifetime, showing convergence of independent approaches for measuring IMM local-order. Mitorotor-1 FLIM reveals mitochondrial heterogeneity in IMM fluidity; between-and-within cells and across single mitochondrion. Multiplexed FLIM lifetime imaging of Mitorotor-1 and NADH autofluorescence reveals that IMM fluidity positively correlates with respiration, across individual cells. Remarkably, we find that stimulating respiration, through nutrient deprivation or chemically, also leads to increase in IMM fluidity. These data suggest that modulating IMM fluidity supports enhanced respiratory flux. Our study presents a robust method for measuring IMM fluidity and suggests a dynamic regulatory paradigm of modulating IMM local order on changing metabolic demand.
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Affiliation(s)
- Gaurav Singh
- Institute for Stem Cell Science and Regenerative Medicine, 560065Bangalore, India
| | - Geen George
- Institute for Stem Cell Science and Regenerative Medicine, 560065Bangalore, India
| | - Sufi O. Raja
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, 500046Hyderabad, India
| | - Ponnuvel Kandaswamy
- Institute for Stem Cell Science and Regenerative Medicine, 560065Bangalore, India
| | - Manoj Kumar
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, 560065Bangalore, India
| | - Shashi Thutupalli
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, 560065Bangalore, India
- International Centre for Theoretical Sciences, Tata Institute for Fundamental Research, 560089 Bangalore, India
| | - Sunil Laxman
- Institute for Stem Cell Science and Regenerative Medicine, 560065Bangalore, India
| | - Akash Gulyani
- Institute for Stem Cell Science and Regenerative Medicine, 560065Bangalore, India
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, 500046Hyderabad, India
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4
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Oka Y. Exclusion of Anchor-Matched Peptide Nucleic Acid from Liquid-Ordered Domains by Hybridization with Complementary Flavin-Labeled DNA. ACS OMEGA 2023; 8:1109-1113. [PMID: 36643542 PMCID: PMC9835180 DOI: 10.1021/acsomega.2c06463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Membrane-anchored proteins and their mimics, such as peptide nucleic acids (PNAs), are known to partition preferentially into either lipid raft/liquid-ordered (lo) domains or into non-raft/liquid-disordered (ld) domains, depending on their lipophilic anchors. Here, anchor-matched PNA was demonstrated to be excluded from the lo microdomains of giant unilamellar vesicles by hybridization with the complementary flavin-labeled DNA. As shown in control experiments using Alexa Fluor 488-labeled DNA, which showed that the preferential partitioning was the lo domain, the domain distribution of PNA was not only dependent on the lipophilic anchor but also on the structure of the hybridized DNA or PNA pair. In such systems, the main factors that influence changes in the domain selectivity of the probes are most likely to also be interactivity (i.e., steric bulkiness), hydrophilicity, and self-assembling ability. These findings may have the potential to contribute to the elucidation of membrane-active peptides, the method of their activation, and their applications in medicine such as antimicrobial use, especially with regard to their actions at the interface between the lo and ld domains in cells.
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5
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Yasuda T, Watanabe H, Hirosawa KM, Suzuki KGN, Suga K, Hanashima S. Fluorescence Spectroscopic Analysis of Lateral and Transbilayer Fluidity of Exosome Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14695-14703. [PMID: 36421004 PMCID: PMC9731264 DOI: 10.1021/acs.langmuir.2c02258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 11/10/2022] [Indexed: 06/16/2023]
Abstract
Exosomes are small extracellular vesicles (sEVs) involved in distal cell-cell communication and cancer migration by transferring functional cargo molecules. Membrane domains similar to lipid rafts are assumed to occur in exosome membranes and are involved in interactions with target cells. However, the bilayer membrane properties of these small vesicles have not been fully investigated. Therefore, we examined the fluidity, lateral domain separation, and transbilayer asymmetry of exosome membranes using fluorescence spectroscopy. Although there were some differences between the exosomes, TMA-DPH anisotropy showing moderate lipid chain order indicated that ordered phases comprised a significant proportion of exosome membranes. Selective TEMPO quenching of the TMA-DPH fluorescence in the liquid-disordered phase indicated that 40-50% of the exosome membrane area belonged to the ordered phase based on a phase-separated model. Furthermore, NBD-PC in the outer leaflet showed longer fluorescence lifetimes than those in the inner leaflets. Therefore, the exosome membranes maintained transbilayer asymmetry with a topology similar to that of the plasma membranes. In addition, the lateral and transbilayer orders of exosome membranes obtained from different cell lines varied, probably depending on the different membrane lipid components and compositions partially derived from donor cells. As these higher membrane orders and asymmetric topologies are similar to those of cell membranes with lipid rafts, raft-like functional domains are possibly enriched on exosome membranes. These domains likely play key roles in the biological functions and cellular uptake of exosomes by facilitating selective membrane interactions with target organs.
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Affiliation(s)
- Tomokazu Yasuda
- Graduate
School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka560-0043, Japan
| | - Hirofumi Watanabe
- Graduate
School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka560-0043, Japan
| | - Koichiro M. Hirosawa
- Institute
for Glyco-core Research (iGCORE), Gifu University, 1-1 Yanagido, Gifu501-1193, Japan
| | - Kenichi G. N. Suzuki
- Institute
for Glyco-core Research (iGCORE), Gifu University, 1-1 Yanagido, Gifu501-1193, Japan
| | - Keishi Suga
- Department
of Chemical Engineering, Tohoku University, 6-6-07, Aoba, Aramaki-aza, Aoba-ku, Sendai, Miyagi980-8579, Japan
| | - Shinya Hanashima
- Graduate
School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka560-0043, Japan
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6
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Dresser L, Graham SP, Miller LM, Schaefer C, Conteduca D, Johnson S, Leake MC, Quinn SD. Tween-20 Induces the Structural Remodeling of Single Lipid Vesicles. J Phys Chem Lett 2022; 13:5341-5350. [PMID: 35678387 PMCID: PMC9208007 DOI: 10.1021/acs.jpclett.2c00704] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/31/2022] [Indexed: 05/04/2023]
Abstract
The solubilization of lipid membranes by Tween-20 is crucial for a number of biotechnological applications, but the mechanistic details remain elusive. Evidence from ensemble assays supports a solubilization model that encompasses surfactant association with the membrane and the release of mixed micelles to solution, but whether this process also involves intermediate transitions between regimes is unanswered. In search of mechanistic origins, increasing focus is placed on identifying Tween-20 interactions with controllable membrane mimetics. Here, we employed ultrasensitive biosensing approaches, including single-vesicle spectroscopy based on fluorescence and energy transfer from membrane-encapsulated molecules, to interrogate interactions between Tween-20 and submicrometer-sized vesicles below the optical diffraction limit. We discovered that Tween-20, even at concentrations below the critical micellar concentration, triggers stepwise and phase-dependent structural remodeling events, including permeabilization and swelling, in both freely diffusing and surface-tethered vesicles, highlighting the substantial impact the surfactant has on vesicle conformation and stability prior to lysis.
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Affiliation(s)
- Lara Dresser
- Department
of Physics, University of York, York YO10 5DD, U.K.
| | - Sarah P. Graham
- Department
of Physics, University of York, York YO10 5DD, U.K.
| | - Lisa M. Miller
- Department
of Electronic Engineering, University of
York, York YO10 5DD, U.K.
| | | | | | - Steven Johnson
- Department
of Electronic Engineering, University of
York, York YO10 5DD, U.K.
- York
Biomedical Research Institute, University
of York, York YO10 5DD, U.K.
| | - Mark C. Leake
- Department
of Physics, University of York, York YO10 5DD, U.K.
- Department
of Biology, University of York, York YO10 5DD, U.K.
- York
Biomedical Research Institute, University
of York, York YO10 5DD, U.K.
| | - Steven D. Quinn
- Department
of Physics, University of York, York YO10 5DD, U.K.
- York
Biomedical Research Institute, University
of York, York YO10 5DD, U.K.
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7
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Infrared Spectroscopic Study of Multi-Component Lipid Systems: A Closer Approximation to Biological Membrane Fluidity. MEMBRANES 2022; 12:membranes12050534. [PMID: 35629860 PMCID: PMC9147058 DOI: 10.3390/membranes12050534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 05/05/2022] [Accepted: 05/16/2022] [Indexed: 01/10/2023]
Abstract
Membranes are essential to cellular organisms, and play several roles in cellular protection as well as in the control and transport of nutrients. One of the most critical membrane properties is fluidity, which has been extensively studied, using mainly single component systems. In this study, we used Fourier transform infrared spectroscopy to evaluate the thermal behavior of multi-component supported lipid bilayers that mimic the membrane composition of tumoral and non-tumoral cell membranes, as well as microorganisms such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus. The results showed that, for tumoral and non-tumoral membrane models, the presence of cholesterol induced a loss of cooperativity of the transition. However, in the absence of cholesterol, the transitions of the multi-component lipid systems had sigmoidal curves where the gel and fluid phases are evident and where main transition temperatures were possible to determine. Additionally, the possibility of designing multi-component lipid systems showed the potential to obtain several microorganism models, including changes in the cardiolipin content associated with the resistance mechanism in Staphylococcus aureus. Finally, the potential use of multi-component lipid systems in the determination of the conformational change of the antimicrobial peptide LL-37 was studied. The results showed that LL-37 underwent a conformational change when interacting with Staphylococcus aureus models, instead of with the erythrocyte membrane model. The results showed the versatile applications of multi-component lipid systems studied by Fourier transform infrared spectroscopy.
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8
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Chatterjee A, Sharma AK, Purkayastha P. Development of a carbon dot and methylene blue NIR-emitting FLIM-FRET pair in niosomes for controlled ROS generation. NANOSCALE 2022; 14:6570-6584. [PMID: 35420619 DOI: 10.1039/d2nr01032a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Non-ionic surfactant vesicular systems (niosomes) are structurally similar to lipid vesicles, differing only in the bilayer composition. Herein we report a unique method to generate reactive oxygen species (ROS) utilizing a FLIM-FRET technique involving niosome-trapped yellow emissive carbon dots (YCDs) and methylene blue (MB) in aqueous medium under neutral conditions. Niosomes are biologically important because of their good stability and extremely low toxicity. Fluorescent CDs, emitting in the higher wavelengths on visible light excitation, are of incredible importance in bio-imaging and optoelectronics. Hence, we prepared nitrogen-containing YCDs from a single precursor, o-phenylenediamine, and explained their detailed photophysics upon incorporation into the niosomal bilayer. The YCDs are polarity sensitive, and are rotationally restricted in niosomes, which increases their fluorescence quantum yield from 29% (in water) to 91%. These YCDs are tactically employed to develop a near infrared (NIR) FRET pair with methylene blue (MB), which is a very well-known type-I and type-II photosensitizer. This FRET pair, which emits in the NIR region, is found to be an ideal system to generate ROS by excitation in the lower visible wavelengths. Interestingly, the ROS production by MB from the dissolved oxygen is enhanced inside the niosomes. The donor and the acceptor moieties in this unique NIR-emitting FRET pair display an unprecedented 300 nm Stokes shift. The findings could be influential in bio-imaging in the NIR region evading cellular autofluorescence and the controllably generated ROS can be further applied as a potential photodynamic therapeutic agent.
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Affiliation(s)
- Arunavo Chatterjee
- Department of Chemical Sciences and Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur 741246, WB, India.
| | - Ankit Kumar Sharma
- Department of Chemical Sciences and Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur 741246, WB, India.
| | - Pradipta Purkayastha
- Department of Chemical Sciences and Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur 741246, WB, India.
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9
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Del Frate G, Macchiagodena M, Akhunzada MJ, D'Autilia F, Catte A, Bhattacharjee N, Barone V, Cardarelli F, Brancato G. Probing Liquid-Ordered and Disordered Phases in Lipid Model Membranes: A Combined Theoretical and Spectroscopic Study of a Fluorescent Molecular Rotor. J Phys Chem B 2022; 126:480-491. [PMID: 35001625 PMCID: PMC8785181 DOI: 10.1021/acs.jpcb.1c08324] [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] [Indexed: 11/30/2022]
Abstract
![]()
An integrated theoretical/experimental
strategy has been applied
to the study of environmental effects on the spectroscopic parameters
of 4-(diphenylamino)phtalonitrile (DPAP), a fluorescent molecular
rotor. The computational part starts from the development of an effective
force field for the first excited electronic state of DPAP and proceeds
through molecular dynamics simulations in solvents of different polarities
toward the evaluation of Stokes shifts by quantum mechanics/molecular
mechanics (QM/MM) approaches. The trends of the computed results closely
parallel the available experimental results thus giving confidence
to the interpretation of new experimental studies of the photophysics
of DPAP in lipid bilayers. In this context, results show unambiguously
that both flexible dihedral angles and global rotations are significantly
retarded in a cholesterol/DPPC lipid matrix with respect to the DOPC
matrix, thus confirming the sensitivity of DPAP to probe different
environments and, therefore, its applicability as a probe for detecting
different structures and levels of plasma membrane organization.
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Affiliation(s)
| | | | | | - Francesca D'Autilia
- Center for Nanotechnology Innovation@NEST (CNI@NEST), Piazza San Silvestro 12, I-56127 Pisa, Italy
| | - Andrea Catte
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
| | | | - Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy.,Istituto Nazionale di Fisica Nucleare(INFN), Largo Pontecorvo 3, I-56 127 Pisa, Italy.,Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase (CSGI), Via della Lastruccia 3, I-50 019 Sesto Fiorentino, Florence, Italy
| | | | - Giuseppe Brancato
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy.,Istituto Nazionale di Fisica Nucleare(INFN), Largo Pontecorvo 3, I-56 127 Pisa, Italy.,Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase (CSGI), Via della Lastruccia 3, I-50 019 Sesto Fiorentino, Florence, Italy
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10
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Rajan S, de Guzman HC, Palaia T, Goldberg IJ, Hussain MM. A simple, rapid, and sensitive fluorescence-based method to assess triacylglycerol hydrolase activity. J Lipid Res 2021; 62:100115. [PMID: 34508728 PMCID: PMC8488599 DOI: 10.1016/j.jlr.2021.100115] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 08/26/2021] [Accepted: 08/30/2021] [Indexed: 01/22/2023] Open
Abstract
Lipases constitute an important class of water-soluble enzymes that catalyze the hydrolysis of hydrophobic triacylglycerol (TAG). Their enzymatic activity is typically measured using multistep procedures involving isolation and quantification of the hydrolyzed products. We report here a new fluorescence method to measure lipase activity in real time that does not require the separation of substrates from products. We developed this method using adipose triglyceride lipase (ATGL) and lipoprotein lipase (LpL) as model lipases. We first incubated a source of ATGL or LpL with substrate vesicles containing nitrobenzoxadiazole (NBD)-labeled TAG, then measured increases in NBD fluorescence, and calculated enzyme activities. Incorporation of NBD-TAG into phosphatidylcholine (PC) vesicles resulted in some hydrolysis; however, incorporation of phosphatidylinositol into these NBD-TAG/PC vesicles and increasing the ratio of NBD-TAG to PC greatly enhanced substrate hydrolysis. This assay was also useful in measuring the activity of pancreatic lipase and hormone-sensitive lipase. Next, we tested several small-molecule lipase inhibitors and found that orlistat inhibits all lipases, indicating that it is a pan-lipase inhibitor. In short, we describe a simple, rapid, fluorescence-based triacylglycerol hydrolysis assay to assess four major TAG hydrolases: intracellular ATGL and hormone-sensitive lipase, LpL localized at the extracellular endothelium, and pancreatic lipase present in the intestinal lumen. The major advantages of this method are its speed, simplicity, and elimination of product isolation. This assay is potentially applicable to a wide range of lipases, is amenable to high-throughput screening to discover novel modulators of triacylglycerol hydrolases, and can be used for diagnostic purposes.
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Affiliation(s)
- Sujith Rajan
- Department of Foundations of Medicine, NYU Long Island School of Medicine, and Diabetes and Obesity Research Center, NYU Langone Hospitals - Long Island, Mineola, NY, USA
| | - Hazel C de Guzman
- Department of Foundations of Medicine, NYU Long Island School of Medicine, and Diabetes and Obesity Research Center, NYU Langone Hospitals - Long Island, Mineola, NY, USA; Department of Environmental Medicine, NYU Grossman School of Medicine, New York, NY, USA
| | - Thomas Palaia
- Department of Foundations of Medicine, NYU Long Island School of Medicine, and Diabetes and Obesity Research Center, NYU Langone Hospitals - Long Island, Mineola, NY, USA
| | - Ira J Goldberg
- Division of Endocrinology, Department of Medicine, NYU Grossman School of Medicine, New York, NY, USA
| | - M Mahmood Hussain
- Department of Foundations of Medicine, NYU Long Island School of Medicine, and Diabetes and Obesity Research Center, NYU Langone Hospitals - Long Island, Mineola, NY, USA; VA New York Harbor Healthcare System, Brooklyn, NY, USA.
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11
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Lukina M, Yashin K, Kiseleva EE, Alekseeva A, Dudenkova V, Zagaynova EV, Bederina E, Medyanic I, Becker W, Mishra D, Berezin M, Shcheslavskiy VI, Shirmanova M. Label-Free Macroscopic Fluorescence Lifetime Imaging of Brain Tumors. Front Oncol 2021; 11:666059. [PMID: 34109119 PMCID: PMC8181388 DOI: 10.3389/fonc.2021.666059] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/27/2021] [Indexed: 01/20/2023] Open
Abstract
Advanced stage glioma is the most aggressive form of malignant brain tumors with a short survival time. Real-time pathology assisted, or image guided surgical procedures that eliminate tumors promise to improve the clinical outcome and prolong the lives of patients. Our work is focused on the development of a rapid and sensitive assay for intraoperative diagnostics of glioma and identification of optical markers essential for differentiation between tumors and healthy brain tissues. We utilized fluorescence lifetime imaging (FLIM) of endogenous fluorophores related to metabolism of the glioma from freshly excised brains tissues. Macroscopic time-resolved fluorescence images of three intracranial animal glioma models and surgical samples of patients' glioblastoma together with the white matter have been collected. Several established and new algorithms were applied to identify the imaging markers of the tumors. We found that fluorescence lifetime parameters characteristic of the glioma provided background for differentiation between the tumors and intact brain tissues. All three rat tumor models demonstrated substantial differences between the malignant and normal tissue. Similarly, tumors from patients demonstrated statistically significant differences from the peritumoral white matter without infiltration. While the data and the analysis presented in this paper are preliminary and further investigation with a larger number of samples is required, the proposed approach based on the macroscopic FLIM has a high potential for diagnostics of glioma and evaluation of the surgical margins of gliomas.
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Affiliation(s)
- Maria Lukina
- Institute of Experimental Oncology and Biomedical Technologies, Privolzhsky Research Medical University, Nizhny Novgorod, Russia
| | - Konstantin Yashin
- Institute of Experimental Oncology and Biomedical Technologies, Privolzhsky Research Medical University, Nizhny Novgorod, Russia
| | - Elena E. Kiseleva
- Institute of Experimental Oncology and Biomedical Technologies, Privolzhsky Research Medical University, Nizhny Novgorod, Russia
| | - Anna Alekseeva
- Department of Neuromorphology, Research Institute of Human Morphology, Moscow, Russia
| | - Varvara Dudenkova
- Institute of Experimental Oncology and Biomedical Technologies, Privolzhsky Research Medical University, Nizhny Novgorod, Russia
| | - Elena V. Zagaynova
- Institute of Experimental Oncology and Biomedical Technologies, Privolzhsky Research Medical University, Nizhny Novgorod, Russia
- Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia
| | - Evgenia Bederina
- Institute of Experimental Oncology and Biomedical Technologies, Privolzhsky Research Medical University, Nizhny Novgorod, Russia
| | - Igor Medyanic
- Institute of Experimental Oncology and Biomedical Technologies, Privolzhsky Research Medical University, Nizhny Novgorod, Russia
| | | | - Deependra Mishra
- Department of Radiology, Washington University School of Medicine, St Louis, MO, United States
| | - Mikhail Berezin
- Department of Radiology, Washington University School of Medicine, St Louis, MO, United States
| | - Vladislav I. Shcheslavskiy
- Institute of Experimental Oncology and Biomedical Technologies, Privolzhsky Research Medical University, Nizhny Novgorod, Russia
- Becker&Hickl GmbH, Berlin, Germany
| | - Marina Shirmanova
- Institute of Experimental Oncology and Biomedical Technologies, Privolzhsky Research Medical University, Nizhny Novgorod, Russia
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12
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Sych T, Gurdap CO, Wedemann L, Sezgin E. How Does Liquid-Liquid Phase Separation in Model Membranes Reflect Cell Membrane Heterogeneity? MEMBRANES 2021; 11:323. [PMID: 33925240 PMCID: PMC8146956 DOI: 10.3390/membranes11050323] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 04/22/2021] [Accepted: 04/26/2021] [Indexed: 11/22/2022]
Abstract
Although liquid-liquid phase separation of cytoplasmic or nuclear components in cells has been a major focus in cell biology, it is only recently that the principle of phase separation has been a long-standing concept and extensively studied in biomembranes. Membrane phase separation has been reconstituted in simplified model systems, and its detailed physicochemical principles, including essential phase diagrams, have been extensively explored. These model membrane systems have proven very useful to study the heterogeneity in cellular membranes, however, concerns have been raised about how reliably they can represent native membranes. In this review, we will discuss how phase-separated membrane systems can mimic cellular membranes and where they fail to reflect the native cell membrane heterogeneity. We also include a few humble suggestions on which phase-separated systems should be used for certain applications, and which interpretations should be avoided to prevent unreliable conclusions.
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Affiliation(s)
| | | | | | - Erdinc Sezgin
- Science for Life Laboratory, Department of Women’s and Children’s Health, Karolinska Institutet, 17165 Solna, Sweden; (T.S.); (C.O.G.); (L.W.)
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13
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Perazzo A, Gallier S, Liuzzi R, Guido S, Caserta S. Quantitative methods to detect phospholipids at the oil-water interface. Adv Colloid Interface Sci 2021; 290:102392. [PMID: 33740709 DOI: 10.1016/j.cis.2021.102392] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 02/23/2021] [Accepted: 02/23/2021] [Indexed: 01/29/2023]
Abstract
Phospholipids are the main constituents of cell membranes and act as natural stabilizers of milk fat globules. Phospholipids are used in a wide range of applications, e.g. as emulsifiers in cosmetic, pharmaceutical and food products. While processed emulsion droplets are usually stabilized by a monolayer of phospholipids, cell membranes have a phospholipid bilayer structure and milk fat globules are stabilized by a complex phospholipid trilayer membrane. Despite the broad relevance of phospholipids, there are still many scientific challenges in understanding how their behavior at the fluid-fluid interface affects microstructure, stability, and physico-chemical properties of natural and industrial products. Most of these challenges arise from the experimental difficulties related to the investigation of the molecular arrangement of phospholipids in situ at the fluid-fluid interface and the quantification of their partitioning between the bulk phase and the interface, both under static and flow conditions. This task is further complicated by the presence of other surface-active components, such as proteins, that can interact with phospholipids and compete for space at the interface. Here, we review the methodologies available from the literature to detect and quantify phospholipids, focusing on oil-water interfaces, and highlight current limitations and future perspectives.
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Affiliation(s)
- Antonio Perazzo
- Novaflux Inc., 1 Wall Street, Princeton, NJ, 08540, United States; Advanced BioDevices LLC., 1 Wall Street, Princeton, NJ, 08540, United States
| | - Sophie Gallier
- Dairy Goat Co-operative (N.Z.) Limited, 18 Gallagher Drive, PO Box 1398, Hamilton 3240, New Zealand
| | - Roberta Liuzzi
- Department of Chemical, Materials and Production Engineering, University of Naples "Federico II", P.le Ascarelli 80, 80125 Napoli, Italy
| | - Stefano Guido
- Department of Chemical, Materials and Production Engineering, University of Naples "Federico II", P.le Ascarelli 80, 80125 Napoli, Italy; Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), UdR INSTM Napoli Federico II, P.le Ascarelli 80, 80125 Napoli, Italy; CEINGE - Biotecnologie Avanzate, Via G. Salvatore 486, 80145 Napoli, Italy.
| | - Sergio Caserta
- Department of Chemical, Materials and Production Engineering, University of Naples "Federico II", P.le Ascarelli 80, 80125 Napoli, Italy; Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), UdR INSTM Napoli Federico II, P.le Ascarelli 80, 80125 Napoli, Italy; CEINGE - Biotecnologie Avanzate, Via G. Salvatore 486, 80145 Napoli, Italy
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14
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Wiemann JT, Shen Z, Ye H, Li Y, Yu Y. Membrane poration, wrinkling, and compression: deformations of lipid vesicles induced by amphiphilic Janus nanoparticles. NANOSCALE 2020; 12:20326-20336. [PMID: 33006360 DOI: 10.1039/d0nr05355d] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Building upon our previous studies on interactions of amphiphilic Janus nanoparticles with glass-supported lipid bilayers, we study here how these Janus nanoparticles perturb the structural integrity and induce shape instabilities of membranes of giant unilamellar vesicles (GUVs). We show that 100 nm amphiphilic Janus nanoparticles disrupt GUV membranes at a threshold particle concentration similar to that in supported lipid bilayers, but cause drastically different membrane deformations, including membrane wrinkling, protrusion, poration, and even collapse of entire vesicles. By combining experiments with molecular simulations, we reveal how Janus nanoparticles alter local membrane curvature and collectively compress the membrane to induce shape transformation of vesicles. Our study demonstrates that amphiphilic Janus nanoparticles disrupt vesicle membranes differently and more effectively than uniform amphiphilic particles.
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Affiliation(s)
- Jared T Wiemann
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.
| | - Zhiqiang Shen
- Department of Mechanical Engineering, University of Connecticut, Storrs, Connecticut 06269, USA
| | - Huilin Ye
- Department of Mechanical Engineering, University of Connecticut, Storrs, Connecticut 06269, USA
| | - Ying Li
- Department of Mechanical Engineering and Polymer Program, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA.
| | - Yan Yu
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.
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15
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Datta R, Heaster TM, Sharick JT, Gillette AA, Skala MC. Fluorescence lifetime imaging microscopy: fundamentals and advances in instrumentation, analysis, and applications. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:1-43. [PMID: 32406215 PMCID: PMC7219965 DOI: 10.1117/1.jbo.25.7.071203] [Citation(s) in RCA: 270] [Impact Index Per Article: 67.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 04/24/2020] [Indexed: 05/18/2023]
Abstract
SIGNIFICANCE Fluorescence lifetime imaging microscopy (FLIM) is a powerful technique to distinguish the unique molecular environment of fluorophores. FLIM measures the time a fluorophore remains in an excited state before emitting a photon, and detects molecular variations of fluorophores that are not apparent with spectral techniques alone. FLIM is sensitive to multiple biomedical processes including disease progression and drug efficacy. AIM We provide an overview of FLIM principles, instrumentation, and analysis while highlighting the latest developments and biological applications. APPROACH This review covers FLIM principles and theory, including advantages over intensity-based fluorescence measurements. Fundamentals of FLIM instrumentation in time- and frequency-domains are summarized, along with recent developments. Image segmentation and analysis strategies that quantify spatial and molecular features of cellular heterogeneity are reviewed. Finally, representative applications are provided including high-resolution FLIM of cell- and organelle-level molecular changes, use of exogenous and endogenous fluorophores, and imaging protein-protein interactions with Förster resonance energy transfer (FRET). Advantages and limitations of FLIM are also discussed. CONCLUSIONS FLIM is advantageous for probing molecular environments of fluorophores to inform on fluorophore behavior that cannot be elucidated with intensity measurements alone. Development of FLIM technologies, analysis, and applications will further advance biological research and clinical assessments.
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Affiliation(s)
- Rupsa Datta
- Morgridge Institute for Research, Madison, Wisconsin, United States
| | - Tiffany M. Heaster
- Morgridge Institute for Research, Madison, Wisconsin, United States
- University of Wisconsin, Department of Biomedical Engineering, Madison, Wisconsin, United States
| | - Joe T. Sharick
- Morgridge Institute for Research, Madison, Wisconsin, United States
| | - Amani A. Gillette
- Morgridge Institute for Research, Madison, Wisconsin, United States
- University of Wisconsin, Department of Biomedical Engineering, Madison, Wisconsin, United States
| | - Melissa C. Skala
- Morgridge Institute for Research, Madison, Wisconsin, United States
- University of Wisconsin, Department of Biomedical Engineering, Madison, Wisconsin, United States
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16
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Gupta A, Korte T, Herrmann A, Wohland T. Plasma membrane asymmetry of lipid organization: fluorescence lifetime microscopy and correlation spectroscopy analysis. J Lipid Res 2020; 61:252-266. [PMID: 31857388 PMCID: PMC6997606 DOI: 10.1194/jlr.d119000364] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 12/03/2019] [Indexed: 02/06/2023] Open
Abstract
A fundamental feature of the eukaryotic cell membrane is the asymmetric arrangement of lipids in its two leaflets. A cell invests significant energy to maintain this asymmetry and uses it to regulate important biological processes, such as apoptosis and vesiculation. The dynamic coupling of the inner or cytoplasmic and outer or exofacial leaflets is a challenging open question in membrane biology. Here, we combined fluorescence lifetime imaging microscopy (FLIM) with imaging total internal reflection fluorescence correlation spectroscopy (ITIR-FCS) to differentiate the dynamics and organization of the two leaflets of live mammalian cells. We characterized the biophysical properties of fluorescent analogs of phosphatidylcholine, sphingomyelin, and phosphatidylserine in the plasma membrane of two mammalian cell lines (CHO-K1 and RBL-2H3). Because of their specific transverse membrane distribution, these probes allowed leaflet-specific investigation of the plasma membrane. We compared the results of the two methods having different temporal and spatial resolution. Fluorescence lifetimes of fluorescent lipid analogs were in ranges characteristic for the liquid ordered phase in the outer leaflet and for the liquid disordered phase in the inner leaflet. The observation of a more fluid inner leaflet was supported by free diffusion in the inner leaflet, with high average diffusion coefficients. The liquid ordered phase in the outer leaflet was accompanied by slower diffusion and diffusion with intermittent transient trapping. Our results show that the combination of FLIM and ITIR-FCS with specific fluorescent lipid analogs is a powerful tool for investigating lateral and transbilayer characteristics of plasma membrane in live cell lines.
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Affiliation(s)
- Anjali Gupta
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences National University of Singapore, Singapore
| | - Thomas Korte
- Institute for Biology/Biophysics, Faculty of Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Andreas Herrmann
- Institute for Biology/Biophysics, Faculty of Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Thorsten Wohland
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences National University of Singapore, Singapore
- Department of Chemistry, National University of Singapore, Singapore
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17
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de Vries WC, Kudruk S, Grill D, Niehues M, Matos ALL, Wissing M, Studer A, Gerke V, Ravoo BJ. Controlled Cellular Delivery of Amphiphilic Cargo by Redox-Responsive Nanocontainers. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1901935. [PMID: 31871866 PMCID: PMC6918114 DOI: 10.1002/advs.201901935] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 10/06/2019] [Indexed: 05/08/2023]
Abstract
The specific transport of amphiphilic compounds such as fluorescently labeled phospholipids into cells is a prerequisite for the analysis of highly dynamic cellular processes involving these molecules, e.g., the intracellular distribution and metabolism of phospholipids. However, cellular delivery remains a challenge as it should not affect the physiological integrity and morphology of the cell membrane. To address this, polymer nanocontainers based on redox-responsive cyclodextrin (CD) amphiphiles are prepared, and their potential to deliver fluorescently labeled phospholipids to intracellular membrane compartments is analyzed. It is shown that mixtures of reductively degradable cyclodextrin amphiphiles and different phospholipids form liposome-like vesicles (CD-lipid vesicles, CSSLV) with a homogeneous distribution of each lipid. Host-guest-mediated self-assembly of a cystamine-crosslinked polymer shell on these CSSLV produces polymer-shelled liposomal vesicles (PSSCSSLV) with the unique feature of a redox-sensitive CSSLV core and reductively degradable polymer shell. PSSCSSLV show high stability and a redox-sensitive release of the amphiphilic cargo. Live cell experiments reveal that the novel PSSCSSLV are readily internalized by primary human endothelial cells and that the reductive microenvironment of the cells' endosomes triggers the release of the amphiphilic cargo into the cytosol. Thus, PSSCSSLV represent a highly efficient system to transport lipid-like amphiphilic cargo into the intracellular environment.
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Affiliation(s)
- Wilke C. de Vries
- Center for Soft Nanoscience and Organic Chemistry InstituteWestfälische Wilhelms‐Universität MünsterBusso‐Peus‐Str. 10Münster48149Germany
| | - Sergej Kudruk
- Institute of Medical BiochemistryCenter for Molecular Biology of InflammationWestfälische Wilhelms‐Universität MünsterVon‐Esmarch‐Str. 56Münster48149Germany
| | - David Grill
- Institute of Medical BiochemistryCenter for Molecular Biology of InflammationWestfälische Wilhelms‐Universität MünsterVon‐Esmarch‐Str. 56Münster48149Germany
| | - Maximilian Niehues
- Center for Soft Nanoscience and Organic Chemistry InstituteWestfälische Wilhelms‐Universität MünsterBusso‐Peus‐Str. 10Münster48149Germany
| | - Anna Livia Linard Matos
- Institute of Medical BiochemistryCenter for Molecular Biology of InflammationWestfälische Wilhelms‐Universität MünsterVon‐Esmarch‐Str. 56Münster48149Germany
| | - Maren Wissing
- Center for Soft Nanoscience and Organic Chemistry InstituteWestfälische Wilhelms‐Universität MünsterBusso‐Peus‐Str. 10Münster48149Germany
| | - Armido Studer
- Center for Soft Nanoscience and Organic Chemistry InstituteWestfälische Wilhelms‐Universität MünsterBusso‐Peus‐Str. 10Münster48149Germany
| | - Volker Gerke
- Institute of Medical BiochemistryCenter for Molecular Biology of InflammationWestfälische Wilhelms‐Universität MünsterVon‐Esmarch‐Str. 56Münster48149Germany
| | - Bart Jan Ravoo
- Center for Soft Nanoscience and Organic Chemistry InstituteWestfälische Wilhelms‐Universität MünsterBusso‐Peus‐Str. 10Münster48149Germany
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18
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Filipe HAL, Pokorná Š, Hof M, Amaro M, Loura LMS. Orientation of nitro-group governs the fluorescence lifetime of nitrobenzoxadiazole (NBD)-labeled lipids in lipid bilayers. Phys Chem Chem Phys 2019; 21:1682-1688. [PMID: 30418442 DOI: 10.1039/c8cp06064a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Nitrobenzoxadiazole (NBD) labeled lipids are popular fluorescent probes of membrane structure and dynamics, and have been widely used in both model systems and living cells. Irrespective of attachment to the lipid head group or hydrocarbon chains, the NBD fluorophore generally adopts a transverse bilayer location near the host lipid carbonyl/glycerol moieties. Still, considerable variability is observed in the measured fluorescence lifetimes, indicating that overall fluorophore location is not the determinant of NBD fluorescence properties. Combining fluorescence experiments and molecular dynamics simulations, we show that for two almost identical NBD probes, significant differences in fluorophore orientation and fluorescence lifetime are observed. Integrating these findings with literature data, we demonstrate a correlation between NBD orientation and fluorescence lifetime. The latter is longer when the NBD nitro group is predominantly oriented towards the bilayer interior, compared to probes for which it points to the water medium.
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Affiliation(s)
- Hugo A L Filipe
- Coimbra Chemistry Center, University of Coimbra, P-3004-535 Coimbra, Portugal
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19
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Functional link between plasma membrane spatiotemporal dynamics, cancer biology, and dietary membrane-altering agents. Cancer Metastasis Rev 2019; 37:519-544. [PMID: 29860560 DOI: 10.1007/s10555-018-9733-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The cell plasma membrane serves as a nexus integrating extra- and intracellular components, which together enable many of the fundamental cellular signaling processes that sustain life. In order to perform this key function, plasma membrane components assemble into well-defined domains exhibiting distinct biochemical and biophysical properties that modulate various signaling events. Dysregulation of these highly dynamic membrane domains can promote oncogenic signaling. Recently, it has been demonstrated that select membrane-targeted dietary bioactives (MTDBs) have the ability to remodel plasma membrane domains and subsequently reduce cancer risk. In this review, we focus on the importance of plasma membrane domain structural and signaling functionalities as well as how loss of membrane homeostasis can drive aberrant signaling. Additionally, we discuss the intricacies associated with the investigation of these membrane domain features and their associations with cancer biology. Lastly, we describe the current literature focusing on MTDBs, including mechanisms of chemoprevention and therapeutics in order to establish a functional link between these membrane-altering biomolecules, tuning of plasma membrane hierarchal organization, and their implications in cancer prevention.
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20
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Abbandonato G, Storti B, Tonazzini I, Stöckl M, Subramaniam V, Montis C, Nifosì R, Cecchini M, Signore G, Bizzarri R. Lipid-Conjugated Rigidochromic Probe Discloses Membrane Alteration in Model Cells of Krabbe Disease. Biophys J 2018; 116:477-486. [PMID: 30709620 DOI: 10.1016/j.bpj.2018.11.3141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 10/15/2018] [Accepted: 11/16/2018] [Indexed: 01/06/2023] Open
Abstract
The plasma membrane of cells has a complex architecture based on the bidimensional liquid-crystalline bilayer arrangement of phospho- and sphingolipids, which in turn embeds several proteins and is connected to the cytoskeleton. Several studies highlight the spatial membrane organization into more ordered (Lo or lipid raft) and more disordered (Ld) domains. We here report on a fluorescent analog of the green fluorescent protein chromophore that, when conjugated to a phospholipid, enables the quantification of the Lo and Ld domains in living cells on account of its large fluorescence lifetime variation in the two phases. The domain composition is straightforwardly obtained by the phasor approach to confocal fluorescence lifetime imaging, a graphical method that does not require global fitting of the fluorescence decay in every spatial position of the sample. Our imaging strategy was applied to recover the domain composition in human oligodendrocytes at rest and under treatment with galactosylsphingosine (psychosine). Exogenous psychosine administration recapitulates many of the molecular fingerprints of a severe neurological disease, globoid cell leukodystrophy, better known as Krabbe disease. We found out that psychosine progressively destabilizes plasma membrane, as witnessed by a shrinking of the Lo fraction. The unchanged levels of galactosyl ceramidase, i.e., the enzyme lacking in Krabbe disease, upon psychosine treatment suggest that psychosine alters the plasma membrane structure by direct physical effect, as also recently demonstrated in model membranes.
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Affiliation(s)
- Gerardo Abbandonato
- NEST, Scuola Normale Superiore and Istituto Nanoscienze CNR (NANO-CNR), Piazza San Silvestro, Pisa, Italy
| | - Barbara Storti
- NEST, Scuola Normale Superiore and Istituto Nanoscienze CNR (NANO-CNR), Piazza San Silvestro, Pisa, Italy
| | - Ilaria Tonazzini
- NEST, Scuola Normale Superiore and Istituto Nanoscienze CNR (NANO-CNR), Piazza San Silvestro, Pisa, Italy
| | - Martin Stöckl
- Bioimaging Center, Department of Biology, Universität Konstanz, Konstanz, Germany
| | - Vinod Subramaniam
- Vrije Universiteit Amsterdam, Amsterdam, The Netherlands; Nanobiophysics, MESA+ Institute for Nanotechnology and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Costanza Montis
- Department of Chemistry and CSGI, University of Florence, Florence, Italy
| | - Riccardo Nifosì
- NEST, Scuola Normale Superiore and Istituto Nanoscienze CNR (NANO-CNR), Piazza San Silvestro, Pisa, Italy
| | - Marco Cecchini
- NEST, Scuola Normale Superiore and Istituto Nanoscienze CNR (NANO-CNR), Piazza San Silvestro, Pisa, Italy
| | - Giovanni Signore
- NEST, Scuola Normale Superiore and Istituto Nanoscienze CNR (NANO-CNR), Piazza San Silvestro, Pisa, Italy; Center for Nanotechnology Innovation@NEST, Istituto Italiano di Tecnologia, Pisa, Italy.
| | - Ranieri Bizzarri
- NEST, Scuola Normale Superiore and Istituto Nanoscienze CNR (NANO-CNR), Piazza San Silvestro, Pisa, Italy; Department of Chemistry and CSGI, University of Florence, Florence, Italy.
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21
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Shishina AK, Kovrigina EA, Galiakhmetov AR, Rathore R, Kovrigin EL. Study of Förster Resonance Energy Transfer to Lipid Domain Markers Ascertains Partitioning of Semisynthetic Lipidated N-Ras in Lipid Raft Nanodomains. Biochemistry 2018; 57:872-881. [PMID: 29280621 DOI: 10.1021/acs.biochem.7b01181] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cellular membranes are heterogeneous planar lipid bilayers displaying lateral phase separation with the nanometer-scale liquid-ordered phase (also known as "lipid rafts") surrounded by the liquid-disordered phase. Many membrane-associated proteins were found to permanently integrate into the lipid rafts, which is critical for their biological function. Isoforms H and N of Ras GTPase possess a unique ability to switch their lipid domain preference depending on the type of bound guanine nucleotide (GDP or GTP). This behavior, however, has never been demonstrated in vitro in model bilayers with recombinant proteins and therefore has been attributed to the action of binding of Ras to other proteins at the membrane surface. In this paper, we report the observation of the nucleotide-dependent switch of lipid domain preferences of the semisynthetic lipidated N-Ras in lipid raft vesicles in the absence of additional proteins. To detect segregation of Ras molecules in raft and disordered lipid domains, we measured Förster resonance energy transfer between the donor fluorophore, mant, attached to the protein-bound guanine nucleotides, and the acceptor, rhodamine-conjugated lipid, localized into the liquid-disordered domains. Herein, we established that N-Ras preferentially populated raft domains when bound to mant-GDP, while losing its preference for rafts when it was associated with a GTP mimic, mant-GppNHp. At the same time, the isolated lipidated C-terminal peptide of N-Ras was found to be localized outside of the liquid-ordered rafts, most likely in the bulk-disordered lipid. Substitution of the N-terminal G domain of N-Ras with a homologous G domain of H-Ras disrupted the nucleotide-dependent lipid domain switch.
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Affiliation(s)
- Anna K Shishina
- Chemistry Department, Marquette University , P.O. Box 1881, Milwaukee, Wisconsin 53201, United States
| | - Elizaveta A Kovrigina
- Chemistry Department, Marquette University , P.O. Box 1881, Milwaukee, Wisconsin 53201, United States
| | - Azamat R Galiakhmetov
- Chemistry Department, Marquette University , P.O. Box 1881, Milwaukee, Wisconsin 53201, United States
| | - Rajendra Rathore
- Chemistry Department, Marquette University , P.O. Box 1881, Milwaukee, Wisconsin 53201, United States
| | - Evgenii L Kovrigin
- Chemistry Department, Marquette University , P.O. Box 1881, Milwaukee, Wisconsin 53201, United States
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22
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Oka Y, Shishino H. Fluorescence Quenching of Alexa Fluor 488-labeled DNA by Complementary Trp-containing PNA Partitioned in Liquid-ordered Domains. CHEM LETT 2017. [DOI: 10.1246/cl.170755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Yoshimi Oka
- Frontier Research Core for Life Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194
| | - Hisae Shishino
- Frontier Research Core for Life Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194
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23
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Oka Y, Shishino H. Fluorescence Imaging of Disrupted Interfaces between Liquid-Ordered and Liquid-Disordered Domains by a Flavin-Labeled PNA Duplex. ACS OMEGA 2017; 2:2912-2915. [PMID: 31457626 PMCID: PMC6641140 DOI: 10.1021/acsomega.7b00581] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 06/12/2017] [Indexed: 06/10/2023]
Abstract
Lipid rafts and membrane-active peptides are attracting attention because they help understand basic membrane functions. In addition, we focus on flavoproteins playing some physiological roles and explore the model compounds. In this study, we demonstrate that a new flavin probe, composed of palmitoylated peptide nucleic acid (PNA) and its complementary PNA labeled with flavin, targets the liquid-ordered (lo) microdomains and disrupts its interfaces to liquid-disordered (ld) microdomains of giant unilamellar vesicles and can be visualized by using confocal laser scanning microscopy. Surprisingly, as shown in time-lapse images, vesiculation and probe aggregations appear in the lo-ld interfaces, which leads to local disruption of the membrane. We discuss a possible interpretation of the data based on a comparison with control experiments.
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24
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Denz M, Chiantia S, Herrmann A, Mueller P, Korte T, Schwarzer R. Cell cycle dependent changes in the plasma membrane organization of mammalian cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:350-359. [DOI: 10.1016/j.bbamem.2016.12.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 11/24/2016] [Accepted: 12/14/2016] [Indexed: 11/16/2022]
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25
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Imaging Cellular Dynamics with Spectral Relaxation Imaging Microscopy: Distinct Spectral Dynamics in Golgi Membranes of Living Cells. Sci Rep 2016; 6:37038. [PMID: 27872481 PMCID: PMC5131650 DOI: 10.1038/srep37038] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 10/24/2016] [Indexed: 12/03/2022] Open
Abstract
Spectral relaxation from fluorescent probes is a useful technique for determining the dynamics of condensed phases. To this end, we have developed a method based on wide-field spectral fluorescence lifetime imaging microscopy to extract spectral relaxation correlation times of fluorescent probes in living cells. We show that measurement of the phase and modulation of fluorescence from two wavelengths permit the identification and determination of excited state lifetimes and spectral relaxation correlation times at a single modulation frequency. For NBD fluorescence in glycerol/water mixtures, the spectral relaxation correlation time determined by our approach exhibited good agreement with published dielectric relaxation measurements. We applied this method to determine the spectral relaxation dynamics in membranes of living cells. Measurements of the Golgi-specific C6-NBD-ceramide probe in living HeLa cells revealed sub-nanosecond spectral dynamics in the intracellular Golgi membrane and slower nanosecond spectral dynamics in the extracellular plasma membrane. We interpret the distinct spectral dynamics as a result of structural plasticity of the Golgi membrane relative to more rigid plasma membranes. To the best of our knowledge, these results constitute one of the first measurements of Golgi rotational dynamics.
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Worch R, Krupa J, Filipek A, Szymaniec A, Setny P. Three conserved C-terminal residues of influenza fusion peptide alter its behavior at the membrane interface. Biochim Biophys Acta Gen Subj 2016; 1861:97-105. [PMID: 27825831 DOI: 10.1016/j.bbagen.2016.11.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 10/24/2016] [Accepted: 11/03/2016] [Indexed: 11/18/2022]
Abstract
The N-terminal fragment of the viral hemagglutinin HA2 subunit is termed a fusion peptide (HAfp). The 23-amino acid peptide (HAfp1-23) contains three C-terminal W21-Y22-G23 residues which are highly conserved among serotypes of influenza A and has been shown to form a tight helical hairpin very distinct from the boomerang structure of HAfp1-20. We studied the effect of peptide length on fusion properties, structural dynamics, and binding to the membrane interface. We developed a novel fusion visualization assay based on FLIM microscopy on giant unilamellar vesicles (GUV). By means of molecular dynamics simulations and spectroscopic measurements, we show that the presence of the three C-terminal W21-Y22-G23 residues promotes the hairpin formation, which orients perpendicularly to the membrane plane and induces more disorder in the surrounding lipids than the less structured HAfp1-20. Moreover, we report cholesterol-enriched domain formation induced exclusively by the longer fusion peptide.
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Affiliation(s)
| | - Joanna Krupa
- Institute of Physics, Polish Academy of Sciences, Poland
| | - Alicja Filipek
- Institute of Physics, Polish Academy of Sciences, Poland
| | - Anna Szymaniec
- Institute of Physics, Polish Academy of Sciences, Poland
| | - Piotr Setny
- Centre for New Technologies, University of Warsaw, Poland
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Amaro M, Šachl R, Jurkiewicz P, Coutinho A, Prieto M, Hof M. Time-resolved fluorescence in lipid bilayers: selected applications and advantages over steady state. Biophys J 2016; 107:2751-2760. [PMID: 25517142 DOI: 10.1016/j.bpj.2014.10.058] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/23/2014] [Accepted: 10/29/2014] [Indexed: 01/23/2023] Open
Abstract
Fluorescence methods are versatile tools for obtaining dynamic and topological information about biomembranes because the molecular interactions taking place in lipid membranes frequently occur on the same timescale as fluorescence emission. The fluorescence intensity decay, in particular, is a powerful reporter of the molecular environment of a fluorophore. The fluorescence lifetime can be sensitive to the local polarity, hydration, viscosity, and/or presence of fluorescence quenchers/energy acceptors within several nanometers of the vicinity of a fluorophore. Illustrative examples of how time-resolved fluorescence measurements can provide more valuable and detailed information about a system than the time-integrated (steady-state) approach will be presented in this review: 1), determination of membrane polarity and mobility using time-dependent spectral shifts; 2), identification of submicroscopic domains by fluorescence lifetime imaging microscopy; 3), elucidation of membrane leakage mechanisms from dye self-quenching assays; and 4), evaluation of nanodomain sizes by time-resolved Förster resonance energy transfer measurements.
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Affiliation(s)
- Mariana Amaro
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Prague, Czech Republic
| | - Radek Šachl
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Prague, Czech Republic
| | - Piotr Jurkiewicz
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Prague, Czech Republic
| | - Ana Coutinho
- Centre for Molecular Chemistry and Physics and Instituto de Nanociência e Nanotecnologia, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal; Departamento Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
| | - Manuel Prieto
- Centre for Molecular Chemistry and Physics and Instituto de Nanociência e Nanotecnologia, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Martin Hof
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Prague, Czech Republic.
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Worch R, Piecyk K, Kolasa AB, Jankowska-Anyszka M. Translocation of 5' mRNA cap analogue--peptide conjugates across the membranes of giant unilamellar vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:311-7. [PMID: 26654783 DOI: 10.1016/j.bbamem.2015.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 11/18/2015] [Accepted: 12/01/2015] [Indexed: 10/22/2022]
Abstract
Cell-penetrating peptides (CPPs) have been extensively studied because of their ability to deliver various cargo molecules, which are often potential therapeutic agents. However, in most cases, the exact entry mechanism of CPPs is still unknown. In this study, we focused our attention on the membrane permeability sequence (MPS) peptide (AAVALLPAVLLALLAK) conjugated to analogues of a 5' mRNA cap. This unique RNA structure plays a pivotal role in eukaryotic gene expression and has a large therapeutic application potential. We validated the translocation abilities of conjugates across the membranes of giant unilamellar vesicles (GUVs) composed of POPC lipids by application of fluorescence microscopy. Translocation of the MPS peptide itself was observed in contrast to peptide conjugates containing mono- and dinucleotide cap analogues, indicating that even for such small cargos, passive translocation does not occur. However, membrane permeability was observed in the case of conjugated mononucleotides. Fluorescence lifetime microscopy (FLIM) of the C6-NBD-phospholipid revealed changes in lipid packing induced by a penetrating peptide. Our results support the usefulness of artificial membrane systems applied to elucidate membrane crossing mechanisms.
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Affiliation(s)
- Remigiusz Worch
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/45, 02-668 Warsaw, Poland.
| | - Karolina Piecyk
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
| | - Anna Brygida Kolasa
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/45, 02-668 Warsaw, Poland
| | - Marzena Jankowska-Anyszka
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland; Department of Biochemistry, Second Faculty of Medicine, Medical University of Warsaw, Zwirki and Wigury 101, 02-089 Warsaw, Poland.
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29
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Schröter F, Jakop U, Teichmann A, Haralampiev I, Tannert A, Wiesner B, Müller P, Müller K. Lipid dynamics in boar sperm studied by advanced fluorescence imaging techniques. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 45:149-63. [DOI: 10.1007/s00249-015-1084-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 09/09/2015] [Accepted: 09/17/2015] [Indexed: 12/23/2022]
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Kilin V, Glushonkov O, Herdly L, Klymchenko A, Richert L, Mely Y. Fluorescence lifetime imaging of membrane lipid order with a ratiometric fluorescent probe. Biophys J 2015; 108:2521-2531. [PMID: 25992730 PMCID: PMC4457243 DOI: 10.1016/j.bpj.2015.04.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 03/23/2015] [Accepted: 04/03/2015] [Indexed: 12/11/2022] Open
Abstract
To monitor the lateral segregation of lipids into liquid-ordered (Lo) and -disordered (Ld) phases in lipid membranes, environment-sensitive dyes that partition in both phases but stain them differently have been developed. Of particular interest is the dual-color F2N12S probe, which can discriminate the two phases through the ratio of its two emission bands. These bands are associated with the normal (N(∗)) and tautomer (T(∗)) excited-state species that result from an excited-state intramolecular proton transfer. In this work, we investigated the potency of the time-resolved fluorescence parameters of F2N12S to discriminate lipid phases in model and cell membranes. Both the long and mean lifetime values of the T(∗) form of F2N12S were found to differ by twofold between Ld and Lo phases as a result of the restriction in the relative motions of the two aromatic moieties of F2N12S imposed by the highly packed Lo phase. This differed from the changes in the ratio of the two emission bands between the two phases, which mainly resulted from the decreased hydration of the N(∗) form in the Lo phase. Importantly, the strong difference in lifetimes between the two phases was preserved when cholesterol was added to the Ld phase. The two phases could be imaged with high contrast by fluorescence lifetime imaging microscopy (FLIM) on giant unilamellar vesicles. FLIM images of F2N12S-labeled live HeLa cells confirmed that the plasma membrane was mainly in the Lo-like phase. Furthermore, the two phases were found to be homogeneously distributed all over the plasma membrane, indicating that they are highly mixed at the spatiotemporal resolution of the FLIM setup. Finally, FLIM could also be used to sensitively monitor the change in lipid phase upon cholesterol depletion and apoptosis.
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Affiliation(s)
- Vasyl Kilin
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch Cedex, France
| | - Oleksandr Glushonkov
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch Cedex, France
| | - Lucas Herdly
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch Cedex, France
| | - Andrey Klymchenko
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch Cedex, France
| | - Ludovic Richert
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch Cedex, France
| | - Yves Mely
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch Cedex, France.
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Wüstner D, Christensen T, Solanko LM, Sage D. Photobleaching kinetics and time-integrated emission of fluorescent probes in cellular membranes. Molecules 2014; 19:11096-130. [PMID: 25076144 PMCID: PMC6271172 DOI: 10.3390/molecules190811096] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 07/04/2014] [Accepted: 07/10/2014] [Indexed: 12/02/2022] Open
Abstract
Since the pioneering work of Hirschfeld, it is known that time-integrated emission (TiEm) of a fluorophore is independent of fluorescence quantum yield and illumination intensity. Practical implementation of this important result for determining exact probe distribution in living cells is often hampered by the presence of autofluorescence. Using kinetic modelling of photobleaching combined with pixel-wise bleach rate fitting of decay models with an updated plugin to the ImageJ program, it is shown that the TiEm of a fluorophore in living cells can be determined exactly from the product of bleaching amplitude and time constant. This applies to mono-exponential bleaching from the first excited singlet and/or triplet state and to multi-exponential combinations of such processes. The TiEm can be used to correct for illumination shading and background autofluorescence without the need for fluorescent test layers or separate imaging of non-stained cells. We apply the method to simulated images and to images of cells, whose membranes were labelled with fluorescent sterols and sphingolipids. Our bleaching model can be extended to include a probability density function (PDF) of intrinsic bleach rate constants with a memory kernel. This approach results in a time-dependent bleach rate coefficient and is exemplified for fluorescent sterols in restricted intracellular environments, like lipid droplets. We show that for small deviations from the classical exponential bleaching, the TiEm of decay functions with rate coefficients remains largely independent of fluorescence lifetime and illumination, and thereby represents a faithful measure of probe distribution.
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Affiliation(s)
- Daniel Wüstner
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.
| | - Tanja Christensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.
| | - Lukasz M Solanko
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.
| | - Daniel Sage
- Biomedical Imaging Group, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
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32
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Setiawan I, Blanchard GJ. Ethanol-induced perturbations to planar lipid bilayer structures. J Phys Chem B 2014; 118:537-46. [PMID: 24372563 DOI: 10.1021/jp410305m] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We report on the formation of planar lipid bilayer structures on mica where the bilayer contains the phosphocholine 1,2-dioleoyl-sn-phosphatidylcholine (DOPC), cholesterol, sphingomyelin and sulforhodamine-tagged-1,2-dioleoyl-sn-phosphatidylethanolamine (SR-DOPE). Phase separation is seen for the cholesterol domains within the bilayer structure, and exposure of this supported bilayer to controlled concentrations of ethanol reveals organizational changes on both the micrometer- and molecular-length scales. We report steady state fluorescence imaging, fluorescence lifetime imaging, and fluorescence anisotropy decay imaging for these bilayers. These data are complementary to existing information on the interactions of lipid bilayers with ethanol and point to subtle but important changes in the molecular-scale organization of these structures.
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Affiliation(s)
- Iwan Setiawan
- Department of Chemistry, Michigan State University , 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
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33
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Chiantia S, London E. Acyl chain length and saturation modulate interleaflet coupling in asymmetric bilayers: effects on dynamics and structural order. Biophys J 2013; 103:2311-9. [PMID: 23283230 DOI: 10.1016/j.bpj.2012.10.033] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 10/23/2012] [Accepted: 10/26/2012] [Indexed: 01/03/2023] Open
Abstract
A long-standing question about membrane structure and function is the degree to which the physical properties of the inner and outer leaflets of a bilayer are coupled to one another. Using our recently developed methods to prepare asymmetric vesicles, coupling was investigated for vesicles containing phosphatidylcholine (PC) in the inner leaflet and sphingomyelin (SM) in the outer leaflet. The coupling of both lateral diffusion and membrane order was monitored as a function of PC and SM acyl chain structure. The presence in the outer leaflet of brain SM, which decreased outer-leaflet lateral diffusion, had little effect upon lateral diffusion in inner leaflets composed of dioleoyl PC (i.e., diffusion was only weakly coupled in the two leaflets) but did greatly reduce lateral diffusion in inner leaflets composed of PC with one saturated and one oleoyl acyl chain (i.e., diffusion was strongly coupled in these cases). In addition, reduced outer-leaflet diffusion upon introduction of outer-leaflet milk SM or a synthetic C24:0 SM, both of which have long interdigitating acyl chains, also greatly reduce diffusion of inner leaflets composed of dioleoyl PC, indicative of strong coupling. Strikingly, several assays showed that the ordering of the outer leaflet induced by the presence of SM was not reflected in increased lipid order in the inner leaflet, i.e., there was no detectable coupling between inner and outer leaflet membrane order. We propose a model for how lateral diffusion can be coupled in opposite leaflets and discuss how this might impact membrane function.
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Affiliation(s)
- Salvatore Chiantia
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY, USA.
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34
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Sezgin E, Chwastek G, Aydogan G, Levental I, Simons K, Schwille P. Photoconversion of Bodipy-Labeled Lipid Analogues. Chembiochem 2013; 14:695-8. [DOI: 10.1002/cbic.201300038] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Indexed: 11/10/2022]
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35
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Loura LMS. Lateral distribution of NBD-PC fluorescent lipid analogs in membranes probed by molecular dynamics-assisted analysis of Förster Resonance Energy Transfer (FRET) and fluorescence quenching. Int J Mol Sci 2012; 13:14545-64. [PMID: 23203080 PMCID: PMC3509596 DOI: 10.3390/ijms131114545] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 10/29/2012] [Accepted: 11/01/2012] [Indexed: 01/19/2023] Open
Abstract
Förster resonance energy transfer (FRET) is a powerful tool used for many problems in membrane biophysics, including characterization of the lateral distribution of lipid components and other species of interest. However, quantitative analysis of FRET data with a topological model requires adequate choices for the values of several input parameters, some of which are difficult to obtain experimentally in an independent manner. For this purpose, atomistic molecular dynamics (MD) simulations can be potentially useful as they provide direct detailed information on transverse probe localization, relative probe orientation, and membrane surface area, all of which are required for analysis of FRET data. This is illustrated here for the FRET pairs involving 1,6-diphenylhexatriene (DPH) as donor and either 1-palmitoyl,2-(6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino] hexanoyl)- sn-glycero-3-phosphocholine (C6-NBD-PC) or 1-palmitoyl,2-(12-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]dodecanoyl)-sn-glycero-3-phosphocholine (C12-NBD-PC) as acceptors, in fluid vesicles of 1,2-dipalmitoyl-sn-3-glycerophosphocholine (DPPC, 50 °C). Incorporation of results from MD simulations improves the statistical quality of model fitting to the experimental FRET data. Furthermore, the decay of DPH in the presence of moderate amounts of C12-NBD-PC (>0.4 mol%) is consistent with non-random lateral distribution of the latter, at variance with C6-NBD-PC, for which aggregation is ruled out up to 2.5 mol% concentration. These conclusions are supported by analysis of NBD-PC fluorescence self-quenching. Implications regarding the relative utility of these probes in membrane studies are discussed.
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Affiliation(s)
- Luís M S Loura
- Faculty of Pharmacy, University of Coimbra, Health Sciences Campus, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal.
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36
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DBD dyes as fluorescent probes for sensing lipophilic environments. Bioorg Med Chem Lett 2012; 22:5367-71. [DOI: 10.1016/j.bmcl.2012.07.056] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 07/11/2012] [Accepted: 07/13/2012] [Indexed: 11/22/2022]
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37
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Prades J, Funari SS, Gomez-Florit M, Vögler O, Barceló F. Effect of a 2-hydroxylated fatty acid on Cholesterol-rich membrane domains. Mol Membr Biol 2012; 29:333-43. [DOI: 10.3109/09687688.2012.705023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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38
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Uptake of a fluorescent methyl-β-cyclodextrin via clathrin-dependent endocytosis. Chem Phys Lipids 2012; 165:505-11. [DOI: 10.1016/j.chemphyslip.2012.03.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 03/07/2012] [Accepted: 03/22/2012] [Indexed: 11/19/2022]
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39
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Bastos AEP, Marinho HS, Cordeiro AM, de Soure AM, de Almeida RFM. Biophysical properties of ergosterol-enriched lipid rafts in yeast and tools for their study: characterization of ergosterol/phosphatidylcholine membranes with three fluorescent membrane probes. Chem Phys Lipids 2012; 165:577-88. [PMID: 22705749 DOI: 10.1016/j.chemphyslip.2012.06.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 06/01/2012] [Accepted: 06/04/2012] [Indexed: 01/06/2023]
Abstract
In this work, binary mixtures of phospholipid/ergosterol (erg) were studied using three fluorescent membrane probes. The phospholipid was either saturated (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC) or monounsaturated (1-palmitoyl-2-dioleoyl-sn-glycero-3-phosphocholine, POPC) phosphatidylcholine, to evaluate the fluorescence properties of the probes in gel, liquid ordered (l(o)) and liquid disordered (l(d)) phases. The probes have been used previously to study cholesterol-enriched domains, but their photophysical properties in erg-enriched membranes have not been characterized. N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (NBD-DPPE) presents modest blue-shifts upon erg addition, and the changes in the fluorescence lifetime are mainly due to differences in the efficiency of its fluorescence dynamic self-quenching. However, the steady-state fluorescence anisotropy of NBD-DPPE presents well-defined values in each lipid phase. N-(lissamine rhodamine B sulfonyl)-1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (Rhod-DOPE) presents a close to random distribution in erg-rich membranes. There are no appreciable spectral shifts and the steady-state fluorescence anisotropy presents complex behavior, as a result of different photophysical processes. The probe is mostly useful to label l(d) domains in yeast membranes. 4-(2-(6-(Dibutylamino)-2-naphthalenyl)ethenyl)-1-(3-sulfopropyl)-pyridinium (di-4-ANEPPS) is an electrochromic dye with excitation spectra largely insensitive to the presence of erg, but presenting a strong blue-shift of its emission with increasing concentrations of this sterol. Its partition coefficient is favorable to l(o) domains in POPC/erg mixtures. Although the fluorescence properties of di-4-ANEPPS are less sensitive to erg than to chol, in both cases the fluorescence lifetime responds monotonically to sterol mole fraction, becoming significantly longer in the presence of sterol as compared to pure POPC or DPPC bilayers. The probe displays a unique sensitivity to sterol-lipid interaction due to the influence of hydration and H-bonding patterns at the membrane/water interface on its fluorescence properties. This makes di-4-ANEPPS (and possibly similar probes) potentially useful in the study of erg-enriched domains in more complex lipid mixtures and in the membranes of living yeast cells.
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Affiliation(s)
- André E P Bastos
- Centro de Química e Bioquímica, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
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40
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Castro BM, de Almeida RFM, Fedorov A, Prieto M. The photophysics of a Rhodamine head labeled phospholipid in the identification and characterization of membrane lipid phases. Chem Phys Lipids 2012; 165:311-9. [PMID: 22405877 DOI: 10.1016/j.chemphyslip.2012.02.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Revised: 02/21/2012] [Accepted: 02/22/2012] [Indexed: 11/27/2022]
Abstract
The organization of lipids and proteins into domains in cell membranes is currently an established subject within biomembrane research. Fluorescent probes have been used to detect and characterize these membrane lateral heterogeneities. However, a comprehensive understanding of the link between the probes' fluorescence features and membrane lateral organization can only be achieved if their photophysical properties are thoroughly defined. In this work, a systematic characterization of N-(lyssamine Rhodamine B sulfonyl)-1,2-dioleoyl-sn-3-phosphatidylehanolamine (Rhod-DOPE) absorption and fluorescence behavior in gel, liquid-ordered (l(o)) and liquid-disordered (l(d)) model membranes was performed. In agreement with a previous study, it was found that Rhod-DOPE fluorescence lifetimes present a strong sensitivity to lipid phases, becoming significantly shorter in l(o) membranes as the probe membrane concentration increases. The sensitivity of Rhod-DOPE absorption and fluorescence properties to the membrane phase was further explored. In particular, the fluorescence lifetime sensitivity was shown to be a consequence of the enhanced Rhod-DOPE fluorescence dynamic self-quenching, due to the formation of probe-rich membrane domains in these condensed phases that cannot be considered as typical probe aggregates, as excitonic interaction is not observed. The highly efficient dynamic self-quenching was shown to be specific to l(o) phases, pointing to an important effect of membrane dipole potential in this process. Altogether, this work establishes how to use Rhod-DOPE fluorescence properties in the study of membrane lipid lateral heterogeneities, in particular cholesterol-enriched lipid rafts.
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Affiliation(s)
- Bruno M Castro
- Centro de Química Física-Molecular, Instituto Superior Técnico, Universidade Técnica de Lisboa, Portugal.
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41
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Klein AS, Schaefer M, Korte T, Herrmann A, Tannert A. HaCaT keratinocytes exhibit a cholesterol and plasma membrane viscosity gradient during directed migration. Exp Cell Res 2012; 318:809-18. [PMID: 22366262 DOI: 10.1016/j.yexcr.2012.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 01/27/2012] [Accepted: 02/08/2012] [Indexed: 11/29/2022]
Abstract
Keratinocyte migration plays an important role in cutaneous wound healing by supporting the process of reepithelialisation. During directional migration cells develop a polarised shape with an asymmetric distribution of a variety of signalling molecules in their plasma membrane. Here, we investigated front-to-back differences of the physical properties of the plasma membrane of migrating keratinocyte-like HaCaT cells. Using FRAP and fluorescence lifetime analysis, both under TIR illumination, we demonstrate a reduced viscosity of the plasma membrane in the lamellipodia of migrating HaCaT cells compared with the cell rears. This asymmetry is most likely caused by a reduced cholesterol content of the lamellipodia as demonstrated by filipin staining. siRNA-mediated silencing of the cholesterol transporter ABCA1, which is known to redistribute cholesterol from rafts to non-raft regions, as well as pharmacological inhibition of this transporter with glibenclamide, strongly diminished the viscosity gradient of the plasma membrane. In addition, HaCaT cell migration was inhibited by glibenclamide treatment. These data suggest a preferential role of non-raft cholesterol in the establishment of the asymmetric plasma membrane viscosity.
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Affiliation(s)
- Anke S Klein
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Germany
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42
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Fujita M, Lechner B, Barton DA, Overall RL, Wasteneys GO. The missing link: do cortical microtubules define plasma membrane nanodomains that modulate cellulose biosynthesis? PROTOPLASMA 2012; 249 Suppl 1:S59-67. [PMID: 22057629 DOI: 10.1007/s00709-011-0332-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 10/04/2011] [Indexed: 05/08/2023]
Abstract
Cellulose production is a crucial aspect of plant growth and development. It is functionally linked to cortical microtubules, which self-organize into highly ordered arrays often situated in close proximity to plasma membrane-bound cellulose synthase complexes (CSCs). Although most models put forward to explain the microtubule-cellulose relationship have considered mechanisms by which cortical microtubule arrays influence the orientation of cellulose microfibrils, little attention has been paid to how microtubules affect the physicochemical properties of cellulose. A recent study using the model system Arabidopsis, however, indicates that microtubules can modulate the crystalline and amorphous content of cellulose microfibrils. Microtubules are required during rapid growth for reducing crystalline content, which is predicted to increase the degree to which cellulose is tethered by hemicellulosic polysaccharides. Such tethering is, in turn, critical for maintaining unidirectional cell expansion. In this article, we hypothesize that cortical microtubules influence the crystalline content of cellulose either by controlling plasma membrane fluidity or by modulating the deposition of noncellulosic wall components in the vicinity of the CSCs. We discuss the current limitations of imaging technology to address these hypotheses and identify the image acquisition and processing strategies that will integrate live imaging with super resolution three-dimensional information.
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Affiliation(s)
- Miki Fujita
- Department of Botany, The University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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43
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Bastos AE, Scolari S, Stöckl M, de Almeida RF. Applications of Fluorescence Lifetime Spectroscopy and Imaging to Lipid Domains In Vivo. Methods Enzymol 2012; 504:57-81. [DOI: 10.1016/b978-0-12-391857-4.00003-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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44
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New molecular rods — Characterization of their interaction with membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2781-8. [DOI: 10.1016/j.bbamem.2011.08.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 07/15/2011] [Accepted: 08/03/2011] [Indexed: 11/20/2022]
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45
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Wessig P, Wawrzinek R, Möllnitz K, Feldbusch E, Schilde U. A new class of fluorescent dyes based on 1,3-benzodioxole and [1,3]-dioxolo[4.5-f]benzodioxole. Tetrahedron Lett 2011. [DOI: 10.1016/j.tetlet.2011.09.058] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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46
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Quantitative assessment of sterol traffic in living cells by dual labeling with dehydroergosterol and BODIPY-cholesterol. Chem Phys Lipids 2011; 164:221-35. [DOI: 10.1016/j.chemphyslip.2011.01.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Revised: 01/14/2011] [Accepted: 01/24/2011] [Indexed: 11/18/2022]
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47
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Melser S, Molino D, Batailler B, Peypelut M, Laloi M, Wattelet-Boyer V, Bellec Y, Faure JD, Moreau P. Links between lipid homeostasis, organelle morphodynamics and protein trafficking in eukaryotic and plant secretory pathways. PLANT CELL REPORTS 2011; 30:177-193. [PMID: 21120657 DOI: 10.1007/s00299-010-0954-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 11/15/2010] [Indexed: 05/30/2023]
Abstract
The role of lipids as molecular actors of protein transport and organelle morphology in plant cells has progressed over the last years through pharmacological and genetic investigations. The manuscript is reviewing the roles of various lipid families in membrane dynamics and trafficking in eukaryotic cells, and summarizes some of the related physicochemical properties of the lipids involved. The article also focuses on the specific requirements of the sphingolipid glucosylceramide (GlcCer) in Golgi morphology and protein transport through the plant secretory pathway. The use of a specific inhibitor of plant glucosylceramide synthase and selected Arabidopsis thaliana RNAi lines stably expressing several markers of the plant secretory pathway, establishes specific steps sensitive to GlcCer biosynthesis. Collectively, data of the literature demonstrate the existence of links between protein trafficking, organelle morphology, and lipid metabolism/homeostasis in eukaryotic cells including plant cells.
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Affiliation(s)
- Su Melser
- Laboratoire de Biogenèse Membranaire, UMR 5200 Université Bordeaux 2-CNRS, Université Bordeaux 2, case 92, 146 rue Léo-Saignat, 33076 Bordeaux, France.
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48
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Ethanol effects on binary and ternary supported lipid bilayers with gel/fluid domains and lipid rafts. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:405-14. [DOI: 10.1016/j.bbamem.2010.10.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 10/08/2010] [Accepted: 10/12/2010] [Indexed: 12/19/2022]
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49
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Nikolaus J, Scolari S, Bayraktarov E, Jungnick N, Engel S, Pia Plazzo A, Stöckl M, Volkmer R, Veit M, Herrmann A. Hemagglutinin of influenza virus partitions into the nonraft domain of model membranes. Biophys J 2010; 99:489-98. [PMID: 20643067 DOI: 10.1016/j.bpj.2010.04.027] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 04/07/2010] [Accepted: 04/12/2010] [Indexed: 11/16/2022] Open
Abstract
The HA of influenza virus is a paradigm for a transmembrane protein thought to be associated with membrane-rafts, liquid-ordered like nanodomains of the plasma membrane enriched in cholesterol, glycosphingolipids, and saturated phospholipids. Due to their submicron size in cells, rafts can not be visualized directly and raft-association of HA was hitherto analyzed by indirect methods. In this study, we have used GUVs and GPMVs, showing liquid disordered and liquid ordered domains, to directly visualize partition of HA by fluorescence microscopy. We show that HA is exclusively (GUVs) or predominantly (GPMVs) present in the liquid disordered domain, regardless of whether authentic HA or domains containing its raft targeting signals were reconstituted into model membranes. The preferential partition of HA into ld domains and the difference between lo partition in GUV and GPMV are discussed with respect to differences in packaging of lipids in membranes of model systems and living cells suggesting that physical properties of lipid domains in biological membranes are tightly regulated by protein-lipid interactions.
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Affiliation(s)
- Jörg Nikolaus
- Department of Biology, Molecular Biophysics, Humboldt University Berlin, Berlin, Germany
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50
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Loew M, Springer R, Scolari S, Altenbrunn F, Seitz O, Liebscher J, Huster D, Herrmann A, Arbuzova A. Lipid domain specific recruitment of lipophilic nucleic acids: a key for switchable functionalization of membranes. J Am Chem Soc 2010; 132:16066-72. [PMID: 20964327 DOI: 10.1021/ja105714r] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Lipid domains in mammalian plasma membranes serve as platforms for specific recruitment or separation of proteins involved in various functions. Here, we have applied this natural strategy of lateral separation to functionalize lipid membranes at micrometer scale in a switchable and reversible manner. Membrane-anchored peptide nucleic acid and DNA, differing in their lipophilic moieties, partition into different lipid domains in model and biological membranes. Separation was visualized by hybridization with the respective complementary fluorescently labeled DNA strands. Upon heating, domains vanished, and both lipophilic nucleic acid structures intermixed with each other. Reformation of the lipid domains by cooling led again to separation of membrane-anchored nucleic acids. By linking appropriate structures/functions to complementary strands, this approach offers a reversible tool for triggering interactions among the structures and for the arrangement of reactions and signaling cascades on biomimetic surfaces.
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Affiliation(s)
- Martin Loew
- Institute of Biology/Biophysics, Humboldt-University Berlin, Invalidenstrasse 42, 10115 Berlin, Germany
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