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Cong ATQ, Pimenta RML, Holy J, Heikal AA. Associated anisotropy of intrinsic NAD(P)H for monitoring changes in the metabolic activities of breast cancer cells (4T1) in three-dimensional collagen matrix. Phys Chem Chem Phys 2021; 23:12692-12705. [PMID: 34036961 DOI: 10.1039/d0cp06635d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The majority of in vitro studies of living cells are routinely conducted in a two-dimensional (2D) monolayer culture. Recent studies, however, suggest that 2D cell culture promotes specific types of aberrant cell behaviors due to the growth on non-physiologically stiff surfaces and the lack of the tissue-based extracellular matrix. Here, we investigate the sensitivity of the two-photon (2P) rotational dynamics of the intrinsic reduced nicotinamide adenine dinucleotide (phosphate), NAD(P)H, to changes in the metabolic state of the metastatic murine breast cancer cells (4T1) in 2D monolayer and three-dimensional (3D) collagen matrix cultures. Time-resolved 2P-associated anisotropy measurements reveal that the rotational dynamics of free and enzyme-bound NAD(P)H in 4T1 cells are correlated to changes in the metabolic state of 2D and 3D cell cultures. In addition to the type of cell culture, we also investigated the metabolic response of 4T1 cells to treatment with two metabolic inhibitors (MD1 and TPPBr). The statistical analyses of our results enabled us to identify which of the fitting parameters of the observed time-resolved associate anisotropy of cellular NAD(P)H were significantly sensitive to changes in the metabolic state of 4T1 cells. Using a black-box model, the population fractions of free and bound NAD(P)H were used to estimate the corresponding equilibrium constant and the standard Gibbs free energy changes that are associated with underlying metabolic pathways of 4T1 cells in 2D and 3D cultures. These rotational dynamics analyses are in agreement with the standard 2P-fluorescence lifetime imaging microscopy (FLIM) measurements on the same cell line, cell cultures, and metabolic inhibition. These studies represent an important step towards the development of a noninvasive, time-resolved associated anisotropy to complement 2P-FLIM in order to elucidate the underlying cellular metabolism and metabolic plasticity in more complex in vivo, tumor-like models using intrinsic NADH autofluorescence.
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Affiliation(s)
- Anh T Q Cong
- Department of Chemistry and Biochemistry, Swenson College of Science and Engineering, University of Minnesota Duluth, 1039 University Drive, Duluth, MN 55812, USA.
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2
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Kondoh M, Moritani H, Ishibashi TA. Observation of Translational Diffusion in a Planer Supported Lipid Bilayer Membrane by Total Internal Reflection-Transient Grating Method. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2020. [DOI: 10.1246/bcsj.20200019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Masato Kondoh
- Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan
| | - Hidekazu Moritani
- Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan
| | - Taka-aki Ishibashi
- Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan
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3
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Vinegoni C, Feruglio PF, Gryczynski I, Mazitschek R, Weissleder R. Fluorescence anisotropy imaging in drug discovery. Adv Drug Deliv Rev 2019; 151-152:262-288. [PMID: 29410158 PMCID: PMC6072632 DOI: 10.1016/j.addr.2018.01.019] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 01/29/2018] [Accepted: 01/30/2018] [Indexed: 12/15/2022]
Abstract
Non-invasive measurement of drug-target engagement can provide critical insights in the molecular pharmacology of small molecule drugs. Fluorescence polarization/fluorescence anisotropy measurements are commonly employed in protein/cell screening assays. However, the expansion of such measurements to the in vivo setting has proven difficult until recently. With the advent of high-resolution fluorescence anisotropy microscopy it is now possible to perform kinetic measurements of intracellular drug distribution and target engagement in commonly used mouse models. In this review we discuss the background, current advances and future perspectives in intravital fluorescence anisotropy measurements to derive pharmacokinetic and pharmacodynamic measurements in single cells and whole organs.
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Affiliation(s)
- Claudio Vinegoni
- Center for System Biology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
| | - Paolo Fumene Feruglio
- Center for System Biology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA; Department of Neurological, Biomedical and Movement Sciences, University of Verona, Verona, Italy
| | - Ignacy Gryczynski
- University of North Texas Health Science Center, Institute for Molecular Medicine, Fort Worth, TX, United States
| | - Ralph Mazitschek
- Center for System Biology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Ralph Weissleder
- Center for System Biology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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4
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Iachina I, Antonescu I, Dreier J, Sørensen J, Brewer J. The nanoscopic molecular pathway through human skin. Biochim Biophys Acta Gen Subj 2019; 1863:1226-1233. [DOI: 10.1016/j.bbagen.2019.04.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 03/23/2019] [Accepted: 04/12/2019] [Indexed: 11/15/2022]
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5
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Ramadurai S, Sarangi NK, Maher S, MacConnell N, Bond AM, McDaid D, Flynn D, Keyes TE. Microcavity-Supported Lipid Bilayers; Evaluation of Drug-Lipid Membrane Interactions by Electrochemical Impedance and Fluorescence Correlation Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:8095-8109. [PMID: 31120755 DOI: 10.1021/acs.langmuir.9b01028] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Many drugs have intracellular or membrane-associated targets, thus understanding their interaction with the cell membrane is of value in drug development. Cell-free tools used to predict membrane interactions should replicate the molecular organization of the membrane. Microcavity array-supported lipid bilayer (MSLB) platforms are versatile biophysical models of the cell membrane that combine liposome-like membrane fluidity with stability and addressability. We used an MSLB herein to interrogate drug-membrane interactions across seven drugs from different classes, including nonsteroidal anti-inflammatories: ibuprofen (Ibu) and diclofenac (Dic); antibiotics: rifampicin (Rif), levofloxacin (Levo), and pefloxacin (Pef); and bisphosphonates: alendronate (Ale) and clodronate (Clo). Fluorescence lifetime correlation spectroscopy (FLCS) and electrochemical impedance spectroscopy (EIS) were used to evaluate the impact of drug on 1,2-dioleyl- sn-glycerophosphocholine and binary bilayers over physiologically relevant drug concentrations. Although FLCS data revealed Ibu, Levo, Pef, Ale, and Clo had no impact on lipid lateral mobility, EIS, which is more sensitive to membrane structural change, indicated modest but significant decreases to membrane resistivity consistent with adsorption but weak penetration of drugs at the membrane. Ale and Clo, evaluated at pH 5.25, did not impact the impedance of the membrane except at concentrations exceeding 4 mM. Conversely, Dic and Rif dramatically altered bilayer fluidity, suggesting their translocation through the bilayer, and EIS data showed that resistivity of the membrane decreased substantially with increasing drug concentration. Capacitance changes to the bilayer in most cases were insignificant. Using a Langmuir-Freundlich model to fit the EIS data, we propose Rsat as an empirical value that reflects permeation. Overall, the data indicate that Ibu, Levo, and Pef adsorb at the interface of the lipid membrane but Dic and Rif interact strongly, permeating the membrane core modifying the water/ion permeability of the bilayer structure. These observations are discussed in the context of previously reported data on drug permeability and log P.
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Affiliation(s)
- Sivaramakrishnan Ramadurai
- School of Chemical Sciences and National Centre for Sensor Research , Dublin City University , Dublin 9 , Ireland
| | - Nirod Kumar Sarangi
- School of Chemical Sciences and National Centre for Sensor Research , Dublin City University , Dublin 9 , Ireland
| | - Sean Maher
- School of Chemical Sciences and National Centre for Sensor Research , Dublin City University , Dublin 9 , Ireland
| | - Nicola MacConnell
- School of Chemical Sciences and National Centre for Sensor Research , Dublin City University , Dublin 9 , Ireland
| | - Alan M Bond
- School of Chemistry , Monash University , Clayton , Victoria 3800 , Australia
| | | | | | - Tia E Keyes
- School of Chemical Sciences and National Centre for Sensor Research , Dublin City University , Dublin 9 , Ireland
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6
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Osella S, Di Meo F, Murugan NA, Fabre G, Ameloot M, Trouillas P, Knippenberg S. Combining (Non)linear Optical and Fluorescence Analysis of DiD To Enhance Lipid Phase Recognition. J Chem Theory Comput 2018; 14:5350-5359. [DOI: 10.1021/acs.jctc.8b00553] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Silvio Osella
- Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland
- Department of Theoretical Chemistry and Biology, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - Florent Di Meo
- Faculty of Pharmacy, UMR 1248 INSERM, Limoges University, 2 rue du Docteur Marcland, 87025 Limoges Cedex, France
| | - N. Arul Murugan
- Department of Theoretical Chemistry and Biology, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - Gabin Fabre
- LCSN-EA1069, Faculty of Pharmacy, Limoges University, 2, rue du Dr. Marcland, 87025 Limoges Cedex, France
| | - Marcel Ameloot
- Biomedical Research Institute, Hasselt University, B-3590, Diepenbeek, Belgium
| | - Patrick Trouillas
- Faculty of Pharmacy, UMR 1248 INSERM, Limoges University, 2 rue du Docteur Marcland, 87025 Limoges Cedex, France
- Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University, tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
| | - Stefan Knippenberg
- Department of Theoretical Chemistry and Biology, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology, SE-10691 Stockholm, Sweden
- Biomedical Research Institute, Hasselt University, B-3590, Diepenbeek, Belgium
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Knippenberg S, Fabre G, Osella S, Di Meo F, Paloncýová M, Ameloot M, Trouillas P. Atomistic Picture of Fluorescent Probes with Hydrocarbon Tails in Lipid Bilayer Membranes: An Investigation of Selective Affinities and Fluorescent Anisotropies in Different Environmental Phases. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:9072-9084. [PMID: 29983063 DOI: 10.1021/acs.langmuir.8b01164] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
By reverting to spectroscopy, changes in the biological environment of a fluorescent probe can be monitored and the presence of various phases of the surrounding lipid bilayer membranes can be detected. However, it is currently not always clear in which phase the probe resides. The well-known orange 1,1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbo-cyanine perchlorate (DiI-C18(5)) fluorophore, for instance, and the new, blue BODIPY (4,4-difluoro-4-bora-3 a,4 a-diaza- s-indacene) derivative were experimentally seen to target and highlight identical parts of giant unilamellar vesicles of various compositions, comprising mixtures of dipalmitoylphosphatidylcholine (DPPC), dioleoylphosphatidylcholine (DOPC), sphingomyelin (SM), and cholesterol (Chol). However, it was not clear which of the coexisting membrane phases were visualized (Bacalum et al., Langmuir. 2016, 32, 3495). The present study addresses this issue by utilizing large-scale molecular dynamics simulations and the z-constraint method, which allows evaluating Gibbs free-energy profiles. The current calculations give an indication why, at room temperature, both BODIPY and DiI-C18(5) probes prefer the gel (So) phase in DOPC/DPPC (2:3 molar ratio) and the liquid-ordered (Lo) phase in DOPC/SM/Chol (1:2:1 molar ratio) mixtures. This study highlights the important differences in orientation and location and therefore in efficiency between the probes when they are used in fluorescence microscopy to screen various lipid bilayer membrane phases. Dependent on the lipid composition, the angle between the transition-state dipole moments of both probes and the normal to the membrane is found to deviate clearly from 90°. It is seen that the DiI-C18(5) probe is located in the headgroup region of the SM/Chol mixture, in close contact with water molecules. A fluorescence anisotropy study also indicates that DiI-C18(5) gives rise to a distinctive behavior in the SM/Chol membrane compared to the other considered membranes. The latter behavior has not been seen for the studied BODIPY probe, which is located deeper in the membrane.
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Affiliation(s)
- S Knippenberg
- Department of Theoretical Chemistry and Biology , KTH Royal Institute of Technology , Roslagstullsbacken 15 , S-106 91 Stockholm , Sweden
- Biomedical Research Institute , Hasselt University , Agoralaan Building C , 3590 Diepenbeek , Belgium
| | - G Fabre
- LCSN-EA1069, Faculty of Pharmacy , Limoges University , 2 rue du Dr. Marcland , 87025 Limoges Cedex , France
| | - S Osella
- Centre of New Technologies , University of Warsaw , Banacha 2C , 02-097 Warsaw , Poland
| | - F Di Meo
- Faculty of Pharmacy , INSERM UMR 1248, Limoges University , 2 rue du Docteur Marcland , 87025 Limoges Cedex , France
| | - M Paloncýová
- Department of Theoretical Chemistry and Biology , KTH Royal Institute of Technology , Roslagstullsbacken 15 , S-106 91 Stockholm , Sweden
| | - M Ameloot
- Biomedical Research Institute , Hasselt University , Agoralaan Building C , 3590 Diepenbeek , Belgium
| | - P Trouillas
- Faculty of Pharmacy , INSERM UMR 1248, Limoges University , 2 rue du Docteur Marcland , 87025 Limoges Cedex , France
- Centre of Advanced Technologies and Materials, Faculty of Science , Palacký University , tř. 17 listopadu 12 , 771 46 Olomouc , Czech Republic
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Sasmal M, Bhowmick R, Musha Islam AS, Bhuiya S, Das S, Ali M. Domain-Specific Association of a Phenanthrene-Pyrene-Based Synthetic Fluorescent Probe with Bovine Serum Albumin: Spectroscopic and Molecular Docking Analysis. ACS OMEGA 2018; 3:6293-6304. [PMID: 31458811 PMCID: PMC6644396 DOI: 10.1021/acsomega.8b00186] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 06/01/2018] [Indexed: 05/20/2023]
Abstract
In this report, the interaction between a phenanthrene-pyrene-based fluorescent probe (PPI) and bovine serum albumin (BSA), a transport protein, has been explored by steady-state emission spectroscopy, fluorescence anisotropy, far-ultraviolet circular dichroism (CD), time-resolved spectral measurements, and molecular docking simulation study. The blue shift along with emission enhancement indicates the interaction between PPI and BSA. The binding of the probe causes quenching of BSA fluorescence through both static and dynamic quenching mechanisms, revealing a 1:1 interaction, as delineated from Benesi-Hildebrand plot, with a binding constant of ∼105 M-1, which is in excellent agreement with the binding constant extracted from fluorescence anisotropy measurements. The thermodynamic parameters, ΔH°, ΔS°, and ΔG°, as determined from van't Hoff relationship indicate the predominance of van der Waals/extensive hydrogen-bonding interactions for the binding phenomenon. The molecular docking and site-selective binding studies reveal the predominant binding of PPI in subdomain IIA of BSA. From the fluorescence resonance energy transfer study, the average distance between tryptophan 213 of the BSA donor and the PPI acceptor is found to be 3.04 nm. CD study demonstrates the reduction of α-helical content of BSA protein on binding with PPI, clearly indicating the change of conformation of BSA.
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9
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Lee HB, Cong A, Leopold H, Currie M, Boersma AJ, Sheets ED, Heikal AA. Rotational and translational diffusion of size-dependent fluorescent probes in homogeneous and heterogeneous environments. Phys Chem Chem Phys 2018; 20:24045-24057. [DOI: 10.1039/c8cp03873b] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Macromolecular crowding effects on diffusion depend on the fluorophore structure, the concentration of crowding agents, and the technique employed.
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Affiliation(s)
- Hong Bok Lee
- Department of Chemistry and Biochemistry
- Swenson College of Science and Engineering
- University of Minnesota Duluth
- Duluth
- USA
| | - Anh Cong
- Department of Chemistry and Biochemistry
- Swenson College of Science and Engineering
- University of Minnesota Duluth
- Duluth
- USA
| | - Hannah Leopold
- Department of Chemistry and Biochemistry
- Swenson College of Science and Engineering
- University of Minnesota Duluth
- Duluth
- USA
| | - Megan Currie
- Department of Chemistry and Biochemistry
- Swenson College of Science and Engineering
- University of Minnesota Duluth
- Duluth
- USA
| | | | - Erin D. Sheets
- Department of Chemistry and Biochemistry
- Swenson College of Science and Engineering
- University of Minnesota Duluth
- Duluth
- USA
| | - Ahmed A. Heikal
- Department of Chemistry and Biochemistry
- Swenson College of Science and Engineering
- University of Minnesota Duluth
- Duluth
- USA
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Drücker P, Rühling A, Grill D, Wang D, Draeger A, Gerke V, Glorius F, Galla HJ. Imidazolium Salts Mimicking the Structure of Natural Lipids Exploit Remarkable Properties Forming Lamellar Phases and Giant Vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:1333-1342. [PMID: 27935708 DOI: 10.1021/acs.langmuir.6b03182] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Tailor-made ionic liquids based on imidazolium salts have recently attracted a large amount of attention because of their extraordinary properties and versatile functionality. An intriguing ability to interact with and stabilize membranes has already been reported for 1,3-dialkylimidazolium compounds. We now reveal further insights into the field by investigating 1,3-dimethyl-4,5-dialkylimidazolium (Cn-IMe·HI, n = 7, 11, 15) and 1,3-dibenzyl-4,5-dialkylimidazolium (Cn-IBn·HBr, n = 7, 11, 15) salts. Diverse alkyl chain lengths and headgroups differing in their steric demand were employed for the membrane interface interaction with bilayer membranes imitating the cellular plasma membrane. Membrane hydration properties and domain fluidization were analyzed by fluorescent bilayer probes in direct comparison to established model membranes in a buffered aqueous environment, which resembles the salt content and pH of the cytosol of living cells. Membrane binding and insertion was analyzed via a quartz crystal microbalance and confocal laser scanning microscopy. We show that short-chain 4,5-dialkylimidazolium salts with a bulky headgroup were able to disintegrate membranes. Long-chain imidazolium salts form bilayer membrane vesicles spontaneously and autonomously without the addition of other lipids. These 4,5-dialkylimidazolium salts are highly eligible for further biochemical engineering and drug delivery.
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Affiliation(s)
- Patrick Drücker
- Institute of Biochemistry, University of Münster , Wilhelm-Klemm-Str. 2, D-48149 Münster, Germany
- Department of Cell Biology, Institute of Anatomy, University of Bern , Baltzerstrasse 2, 3000 Bern 9, Switzerland
| | - Andreas Rühling
- Organic Chemistry Institute, University of Münster , Corrensstrasse 40, D-48149 Münster, Germany
| | - David Grill
- Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Münster , Von-Esmarch-Str. 56, D-48149 Münster, Germany
| | - Da Wang
- Institute of Biochemistry, University of Münster , Wilhelm-Klemm-Str. 2, D-48149 Münster, Germany
| | - Annette Draeger
- Department of Cell Biology, Institute of Anatomy, University of Bern , Baltzerstrasse 2, 3000 Bern 9, Switzerland
| | - Volker Gerke
- Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Münster , Von-Esmarch-Str. 56, D-48149 Münster, Germany
| | - Frank Glorius
- Organic Chemistry Institute, University of Münster , Corrensstrasse 40, D-48149 Münster, Germany
| | - Hans-Joachim Galla
- Institute of Biochemistry, University of Münster , Wilhelm-Klemm-Str. 2, D-48149 Münster, Germany
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Abstract
Lipid structures exhibit complex and highly dynamic lateral structure; and changes in lipid density and fluidity are believed to play an essential role in membrane targeting and function. The dynamic structure of liquids on the molecular scale can exhibit complex transient density fluctuations. Here the lateral heterogeneity of lipid dynamics is explored in free standing lipid monolayers. As the temperature is lowered the probes exhibit increasingly broad and heterogeneous rotational correlation. This increase in heterogeneity appears to exhibit a critical onset, similar to those observed for glass forming fluids. We explore heterogeneous relaxation in in a single constituent lipid monolayer of 1, 2-dimyristoyl-sn-glycero-3-phosphocholine by measuring the rotational diffusion of a fluorescent probe (1-palmitoyl-2-[1]-sn-glycero-3-phosphocholine), which is embedded in the lipid monolayer at low labeling density. Dynamic distributions are measured using wide-field time-resolved fluorescence anisotropy. The observed relaxation exhibits a narrow, liquid-like distribution at high temperatures (τ ∼ 2.4 ns), consistent with previous experimental measures (Dadashvand et al 2014 Struct. Dyn. 1 054701, Loura and Ramalho 2007 Biochim. Biophys. Acta 1768 467-478). However, as the temperature is quenched, the distribution broadens, and we observe the appearance of a long relaxation population (τ ∼ 16.5 ns). This supports the heterogeneity observed for lipids at high packing densities, and demonstrates that the nanoscale diffusion and reorganization in lipid structures can be significantly complex, even in the simplest amorphous architectures. Dynamical heterogeneity of this form can have a significant impact on the organization, permeability and energetics of lipid membrane structures.
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Affiliation(s)
- Neda Dadashvand
- Department of Physics, Wesleyan University, Middletown, CT 06457, USA
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Bacalum M, Wang L, Boodts S, Yuan P, Leen V, Smisdom N, Fron E, Knippenberg S, Fabre G, Trouillas P, Beljonne D, Dehaen W, Boens N, Ameloot M. A Blue-Light-Emitting BODIPY Probe for Lipid Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:3495-3505. [PMID: 27003513 DOI: 10.1021/acs.langmuir.6b00478] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Here we describe a new BODIPY-based membrane probe (1) that provides an alternative to dialkylcarbocyanine dyes, such as DiI-C18, that can be excited in the blue spectral region. Compound 1 has unbranched octadecyl chains at the 3,5-positions and a meso-amino function. In organic solvents, the absorption and emission maxima of 1 are determined mainly by solvent acidity and dipolarity. The fluorescence quantum yield is high and reaches 0.93 in 2-propanol. The fluorescence decays are well fitted with a single-exponential in pure solvents and in small and giant unilamellar vesicles (GUV) with a lifetime of ca. 4 ns. Probe 1 partitions in the same lipid phase as DiI-C18(5) for lipid mixtures containing sphingomyelin and for binary mixtures of dipalmitoylphosphatidylcholine (DPPC) and dioleoylphosphatidylcholine (DOPC). The lipid phase has no effect on the fluorescence lifetime but influences the fluorescence anisotropy. The translational diffusion coefficients of 1 in GUVs and OLN-93 cells are of the same order as those reported for DiI-C18. The directions of the absorption and emission transition dipole moments of 1 are calculated to be parallel. This is reflected in the high steady-state fluorescence anisotropy of 1 in high ordered lipid phases. Molecular dynamic simulations of 1 in a model of the DOPC bilayer indicate that the average angle of the transition moments with respect to membrane normal is ca. 70°, which is comparable with the value reported for DiI-C18.
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Affiliation(s)
- Mihaela Bacalum
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590, Diepenbeek, Belgium
- Department of Life and Environmental Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering , Reactorului 30, Măgurele, 077125, Romania
| | - Lina Wang
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Stijn Boodts
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Peijia Yuan
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Volker Leen
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Nick Smisdom
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590, Diepenbeek, Belgium
| | - Eduard Fron
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Stefan Knippenberg
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590, Diepenbeek, Belgium
- Division of Theoretical Chemistry and Biology, KTH Royal Institute of Technology, School of Biotechnology , Roslagstullsbacken 15, S-106 91 Stockholm, Sweden
| | - Gabin Fabre
- LCSN-EA1069, Faculté de Pharmacie, Université de Limoges , 2, rue du Dr. Marcland, 87025 Limoges Cedex, France
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University , tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
| | - Patrick Trouillas
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University , tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
- INSERM UMR-S850, Faculté de Pharmacie, Université de Limoges , 2 rue du Docteur Marcland, 87025 Limoges Cedex, France
- Service de Chimie des Matériaux Nouveaux, Université de Mons , Place du Parc 20, B-7000 Mons, Belgium
| | - David Beljonne
- Service de Chimie des Matériaux Nouveaux, Université de Mons , Place du Parc 20, B-7000 Mons, Belgium
| | - Wim Dehaen
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Noël Boens
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Marcel Ameloot
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590, Diepenbeek, Belgium
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Börner R, Ehrlich N, Hohlbein J, Hübner CG. Single Molecule 3D Orientation in Time and Space: A 6D Dynamic Study on Fluorescently Labeled Lipid Membranes. J Fluoresc 2016; 26:963-75. [DOI: 10.1007/s10895-016-1784-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Accepted: 03/02/2016] [Indexed: 10/22/2022]
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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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15
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Ganguly A, Ghosh S, Guchhait N. Binding of a potential chloride channel blocker with an anionic surfactant and subsequent release in solution: effect of a hydrotropic solute in the post-micellar region. RSC Adv 2014. [DOI: 10.1039/c4ra10456k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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16
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Ngo AT, Jakubek ZJ, Lu Z, Joós B, Morris CE, Johnston LJ. Membrane order parameters for interdigitated lipid bilayers measured via polarized total-internal-reflection fluorescence microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2861-9. [PMID: 25073072 DOI: 10.1016/j.bbamem.2014.07.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 07/03/2014] [Accepted: 07/21/2014] [Indexed: 12/25/2022]
Abstract
Incorporating ethanol in lipid membranes leads to changes in bilayer structure, including the formation of an interdigitated phase. We have used polarized total-internal-reflection fluorescence microscopy (pTIRFM) to measure the order parameter for Texas Red DHPE incorporated in the ethanol-induced interdigitated phase (LβI) formed from ternary lipid mixtures comprising dioleoylphosphatidylcholine, cholesterol and egg sphingomyelin or dipalmitoylphosphatidylcholine. These lipid mixtures have 3 co-existing phases in the presence of ethanol: liquid-ordered, liquid-disordered and LβI. pTIRFM using Texas Red DHPE shows a reversal in fluorescence contrast between the LβI phase and the surrounding disordered phase with changes in the polarization angle. The contrast reversal is due to changes in the orientation of the dye, and provides a rapid method to identify the LβI phase. The measured order parameters for the LβI phase are consistent with a highly ordered membrane environment, similar to a gel phase. An acyl-chain labeled BODIPY-FL-PC was also tested for pTIRFM studies of ethanol-treated bilayers; however, this probe is less useful since the order parameters of the interdigitated phase are consistent with orientations that are close to random, either due to local membrane disorder or to a mixture of extended and looping conformations in which the fluorophore is localized in the polar headgroup region of the bilayer. In summary, we demonstrate that order parameter measurements via pTIRFM using Texas Red-DHPE can rapidly identify the interdigitated phase in supported bilayers. We anticipate that this technique will aid further research in the effects of alcohols and other additives on membranes.
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Affiliation(s)
- An T Ngo
- Measurement Science and Standards, National Research Council Canada, Ottawa, ON K1A 0R6, Canada; Department of Physics, University of Ottawa Ottawa, ON K1N 6N5, Canada
| | - Zygmunt J Jakubek
- Measurement Science and Standards, National Research Council Canada, Ottawa, ON K1A 0R6, Canada
| | - Zhengfang Lu
- Measurement Science and Standards, National Research Council Canada, Ottawa, ON K1A 0R6, Canada
| | - Béla Joós
- Department of Physics, University of Ottawa Ottawa, ON K1N 6N5, Canada
| | | | - Linda J Johnston
- Measurement Science and Standards, National Research Council Canada, Ottawa, ON K1A 0R6, Canada.
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17
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Ganguly A, Paul BK, Ghosh S, Dalapati S, Guchhait N. Interaction of a potential chloride channel blocker with a model transport protein: a spectroscopic and molecular docking investigation. Phys Chem Chem Phys 2014; 16:8465-75. [DOI: 10.1039/c3cp53843e] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Ramirez DMC, Jakubek ZJ, Lu Z, Ogilvie WW, Johnston LJ. Changes in order parameters associated with ceramide-mediated membrane reorganization measured using pTIRFM. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:15907-15918. [PMID: 24308875 DOI: 10.1021/la403585v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The enzymatic generation of ceramide has significant effects on the biophysical properties of lipid bilayers and can lead to the extensive reorganization of cell membranes. We have synthesized and characterized a headgroup-labeled fluorescent lipid probe (NBD-ceramide, NBD-Cer) and demonstrated that it can be used for polarized total internal reflection fluorescence microscopy experiments to probe changes in membrane order that result from ceramide incorporation. NBD-Cer measures significantly higher order parameters for the liquid-ordered (Lo) domains ([P2] = 0.40 ± 0.03) than for the liquid-disordered phase (Ld, fluid, [P2] = 0.22 ± 0.02) of phase-separated bilayers prepared from egg sphingomyelin, dioleolyphosphatidylcholine, and cholesterol mixtures. The probe also responds to changes in packing induced by the direct incorporation of ceramide or the variation in the ionic strength of the aqueous medium. Order parameter maps obtained after enzyme treatment of bilayers with coexisting Lo and Ld phases show two distinct types of behavior. In regions of high enzyme activity, the initial Lo/Ld domains are replaced by large, dark features that have high membrane order corroborating previous hypotheses that these are ceramide-enriched regions of the membrane. In areas of low enzyme activity, the size and shape of the Lo domains are conserved, but there is an increase in the order parameter for the initial Ld phase ([P2] = 0.30 ± 0.01). This is attributed to the incorporation of ceramide in the Lo domains with the concomitant expulsion of cholesterol into the surrounding fluid phase, increasing its order parameter.
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Affiliation(s)
- Daniel M Carter Ramirez
- Measurement Science and Standards, National Research Council of Canada , Ottawa, Ontario K1A 0R6, Canada
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19
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Heikal AA. Time-resolved fluorescence anisotropy and fluctuation correlation analysis of major histocompatibility complex class I proteins in fibroblast cells. Methods 2013; 66:283-91. [PMID: 23811298 DOI: 10.1016/j.ymeth.2013.06.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 06/12/2013] [Accepted: 06/18/2013] [Indexed: 11/26/2022] Open
Abstract
Major histocompatibility complex class I proteins, MHC(I), are expressed in almost all nucleated cells and synthesized in the endoplasmic reticulum (ER). The orientation and mobility of these complexes are crucial in their biological function in the immune system, i.e., the cytosolic pathogen peptides loading and their presentation to T-cell receptors at the plasma membrane, where cell destruction is triggered. Here, we investigate the structural flexibility and associations of GFP-encoded MHC(I) alleles (H2L(d)), namely H2L(d)GFPin and H2L(d)GFPout, in cultured mouse fibroblast cells. Time-resolved fluorescence anisotropy of H2L(d)GFPin in the ER indicates a dominant overall tumbling motion of 56±7 ns (ER), with a fast conformational flexibility, as compared with a restricted rotation of H2L(d)GFPout. At the single-molecule level, the diffusion coefficient of H2L(d)GFPin and H2L(d)GFPout in the ER is (1.8±0.5)×10(-9) and (2.1±0.6)×10(-9) cm(2)/s, respectively, as revealed by fluorescence correlation spectroscopy. A complementary immunoblotting of H2L(d)GFP constructs, isolated from mouse fibroblast cells, reveals band at 75 kDa as compared with 29 kDa of the free EGFP. These real-time dynamics provide new insights into the structural flexibility and intracellular associations of GFP-labeled MHC(I) alleles (H2L(d)) in living cells.
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Affiliation(s)
- Ahmed A Heikal
- Department of Chemistry and Biochemistry, Swenson College of Science and Engineering, University of Minnesota-Duluth, Duluth, MN 55812, USA; Department of Pharmacy Practice and Pharmaceutical Sciences, College of Pharmacy, University of Minnesota-Duluth, Duluth, MN 55812, USA.
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20
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Nuin E, Gómez-Mendoza M, Andreu I, Marin ML, Miranda MA. New Photoactive Compounds To Probe Cholic Acid and Cholesterol inside Mixed Micelles. Org Lett 2012; 15:298-301. [DOI: 10.1021/ol303201y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Edurne Nuin
- Instituto Universitario Mixto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València, Avenida de los Naranjos s/n, 46022 Valencia, Spain, and Unidad Mixta de Investigación IIS La Fe−UPV, Hospital La Fe, Avda. Campanar 21, 46009 Valencia, Spain
| | - Miguel Gómez-Mendoza
- Instituto Universitario Mixto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València, Avenida de los Naranjos s/n, 46022 Valencia, Spain, and Unidad Mixta de Investigación IIS La Fe−UPV, Hospital La Fe, Avda. Campanar 21, 46009 Valencia, Spain
| | - Inmaculada Andreu
- Instituto Universitario Mixto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València, Avenida de los Naranjos s/n, 46022 Valencia, Spain, and Unidad Mixta de Investigación IIS La Fe−UPV, Hospital La Fe, Avda. Campanar 21, 46009 Valencia, Spain
| | - M. Luisa Marin
- Instituto Universitario Mixto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València, Avenida de los Naranjos s/n, 46022 Valencia, Spain, and Unidad Mixta de Investigación IIS La Fe−UPV, Hospital La Fe, Avda. Campanar 21, 46009 Valencia, Spain
| | - Miguel A. Miranda
- Instituto Universitario Mixto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València, Avenida de los Naranjos s/n, 46022 Valencia, Spain, and Unidad Mixta de Investigación IIS La Fe−UPV, Hospital La Fe, Avda. Campanar 21, 46009 Valencia, Spain
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21
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Lagarde M, Bernoud-Hubac N, Guichardant M. Expanding the horizons of lipidomics. Towards fluxolipidomics. Mol Membr Biol 2012; 29:222-8. [PMID: 22594701 DOI: 10.3109/09687688.2012.689378] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
This short review takes into consideration the status of lipidomics as issued from almost a decade of development. Because of the huge number of molecular species analyzed, there is a trend in subdividing lipidomics according to subdomains, in particular relating to the function of molecules. It is also pointed out that lipid imaging without the use of exogenous probes will help making relationships between molecular structures and the topography of lipid assemblies, especially in cellular compartments. Finally, a fluxomics approach is proposed for lipid molecular species, both in terms of compartments and biochemical metabolism. The example of fluxolipidomics of essential fatty acids toward their enzyme-dependent oxygenated metabolites and further toward their degradation products is developed.
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Affiliation(s)
- Michel Lagarde
- UMR 1060 INSERM-CarMeN, IMBL, INSA-Lyon, Villeurbanne 60621, France.
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22
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Heikal AA. A Multiparametric Imaging of Cellular Coenzymes for Monitoring Metabolic and Mitochondrial Activities. REVIEWS IN FLUORESCENCE 2010 2012. [DOI: 10.1007/978-1-4419-9828-6_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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23
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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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24
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Paul BK, Ray D, Guchhait N. Spectral deciphering of the interaction between an intramolecular hydrogen bonded ESIPT drug, 3,5-dichlorosalicylic acid, and a model transport protein. Phys Chem Chem Phys 2012; 14:8892-902. [DOI: 10.1039/c2cp23496c] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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25
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Song KC, Livanec PW, Klauda JB, Kuczera K, Dunn RC, Im W. Orientation of fluorescent lipid analogue BODIPY-PC to probe lipid membrane properties: insights from molecular dynamics simulations. J Phys Chem B 2011; 115:6157-65. [PMID: 21513278 DOI: 10.1021/jp109629v] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Single-molecule fluorescence measurements have been used to characterize membrane properties, and recently showed a linear evolution of the fluorescent lipid analogue BODIPY-PC toward small tilt angles in Langmuir-Blodgett monolayers as the lateral surface pressure is increased. In this work, we have performed comparative molecular dynamics (MD) simulations of BODIPY-PC in DPPC (dipalmitoylphosphatidylcholine) monolayers and bilayers at three surface pressures (3, 10, and 40 mN/m) to explore (1) the microscopic correspondence between monolayer and bilayer structures, (2) the fluorophore's position within the membrane, and (3) the microscopic driving forces governing the fluorophore's tilting. The MD simulations reveal very close agreement between the monolayer and bilayer systems in terms of the fluorophore's orientation and lipid chain order, suggesting that monolayer experiments can be used to approximate bilayer systems. The simulations capture the trend of reduced tilt angle of the fluorophore with increasing surface pressure, as seen in the experimental results, and provide detailed insights into fluorophore location and orientation, not obtainable in the experiments. The simulations also reveal that the enthalpic contribution is dominant at 40 mN/m, resulting in smaller tilt angles of the fluorophore, and the entropy contribution is dominant at lower pressures, resulting in larger tilt angles.
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Affiliation(s)
- Kevin C Song
- Center for Bioinformatics, The University of Kansas, 2030 Becker Drive, Lawrence, Kansas 66047, USA
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26
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Becucci L, Lottini E, Guidelli R. Influence of gel-phase microdomains and lipid rafts in lipid monolayers on the electron transfer of a lipophilic redox probe: dioctadecylviologen. Phys Chem Chem Phys 2011; 13:3917-24. [DOI: 10.1039/c0cp01928c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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A Multiparametric Fluorescence Approach for Biomembrane Studies. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/b978-0-12-387721-5.00005-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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28
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Kiessling V, Domanska MK, Tamm LK. Single SNARE-mediated vesicle fusion observed in vitro by polarized TIRFM. Biophys J 2010; 99:4047-55. [PMID: 21156148 PMCID: PMC3000493 DOI: 10.1016/j.bpj.2010.10.022] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 10/01/2010] [Accepted: 10/15/2010] [Indexed: 10/18/2022] Open
Abstract
Single-vesicle fusion assays in vitro are useful tools for examining mechanisms of membrane fusion at the molecular level mediated by soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). This approach allows the experimentalist to define the lipid and protein composition of the two fusing membranes and perform experiments under highly controlled conditions. In previous experiments, in which we reconstituted a SNARE acceptor complex into supported membranes and observed the docking and fusion of fluorescently labeled synaptobrevin proteoliposomes by total internal reflection fluorescence microscopy with millisecond time resolution, we were able to determine the optimal number of SNARE complexes needed for fast fusion. Here, we utilize this assay in combination with polarized total internal reflection fluorescence microscopy to investigate topology changes that vesicles undergo after the onset of fusion. The theory that describes the fluorescence intensity during the transformation of a single vesicle from a spherical particle to a flat membrane patch is developed and confirmed by experiments with three different fluorescent probes. Our results show that on average, the fusing vesicles flatten and merge into the planar membrane within 8 ms after fusion starts.
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Affiliation(s)
| | | | - Lukas K. Tamm
- Center for Membrane Biology and Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia
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29
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Muddana HS, Gullapalli RR, Manias E, Butler PJ. Atomistic simulation of lipid and DiI dynamics in membrane bilayers under tension. Phys Chem Chem Phys 2010; 13:1368-78. [PMID: 21152516 DOI: 10.1039/c0cp00430h] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Membrane tension modulates cellular processes by initiating changes in the dynamics of its molecular constituents. To quantify the precise relationship between tension, structural properties of the membrane, and the dynamics of lipids and a lipophilic reporter dye, we performed atomistic molecular dynamics (MD) simulations of DiI-labeled dipalmitoylphosphatidylcholine (DPPC) lipid bilayers under physiological lateral tensions ranging from -2.6 mN m(-1) to 15.9 mN m(-1). Simulations showed that the bilayer thickness decreased linearly with tension consistent with volume-incompressibility, and this thinning was facilitated by a significant increase in acyl chain interdigitation at the bilayer midplane and spreading of the acyl chains. Tension caused a significant drop in the bilayer's peak electrostatic potential, which correlated with the strong reordering of water and lipid dipoles. For the low tension regime, the DPPC lateral diffusion coefficient increased with increasing tension in accordance with free-area theory. For larger tensions, free area theory broke down due to tension-induced changes in molecular shape and friction. Simulated DiI rotational and lateral diffusion coefficients were lower than those of DPPC but increased with tension in a manner similar to DPPC. Direct correlation of membrane order and viscosity near the DiI chromophore, which was just under the DPPC headgroup, indicated that measured DiI fluorescence lifetime, which is reported to decrease with decreasing lipid order, is likely to be a good reporter of tension-induced decreases in lipid headgroup viscosity. Together, these results offer new molecular-level insights into membrane tension-related mechanotransduction and into the utility of DiI in characterizing tension-induced changes in lipid packing.
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Affiliation(s)
- Hari S Muddana
- Department of Bioengineering, The Pennsylvania State University, 230 Hallowell Building, University Park, PA, USA
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30
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Farkas ER, Webb WW. Multiphoton polarization imaging of steady-state molecular order in ternary lipid vesicles for the purpose of lipid phase assignment. J Phys Chem B 2010; 114:15512-22. [PMID: 21058681 DOI: 10.1021/jp107025h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We have investigated lipid acyl chain order parameters of giant unilamellar vesicles (GUVs) using multiphoton fluorescence microscopy. We compare two widely used models of lipid acyl chain order parameters: the "wobble-on-a-cone" model and the Gaussian distribution model. For the first time, we systematically address a ternary system for which the phase diagram encompassing both composition and temperature space has been mapped in order to determine tie-line directions and thus phase assignment. In addition, because miscibility and chain melting transitions can be observed directly and simultaneously with multiphoton microscopy, our technique is applicable to determining the extent of the coupling between chain order and miscibility; thus, it provides a more robust platform for comparison with theory.
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Affiliation(s)
- Elaine R Farkas
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
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31
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van Schooneveld MM, Gloter A, Stephan O, Zagonel LF, Koole R, Meijerink A, Mulder WJM, de Groot FMF. Imaging and quantifying the morphology of an organic-inorganic nanoparticle at the sub-nanometre level. NATURE NANOTECHNOLOGY 2010; 5:538-44. [PMID: 20526325 DOI: 10.1038/nnano.2010.105] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 04/26/2010] [Indexed: 05/24/2023]
Abstract
The development of hybrid organic-inorganic nanoparticles is of interest for applications such as drug delivery, DNA and protein recognition, and medical diagnostics. However, the characterization of such nanoparticles remains a significant challenge due to the heterogeneous nature of these particles. Here, we report the direct visualization and quantification of the organic and inorganic components of a lipid-coated silica particle that contains a smaller semiconductor quantum dot. High-angle annular dark-field scanning transmission electron microscopy combined with electron energy loss spectroscopy was used to determine the thickness and chemical signature of molecular coating layers, the element atomic ratios, and the exact positions of different elements in single nanoparticles. Moreover, the lipid ratio and lipid phase segregation were also quantified.
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Affiliation(s)
- Matti M van Schooneveld
- Inorganic Chemistry & Catalysis, Debye Institute, Utrecht University, Sorbonnelaan 16, 3584 CA, The Netherlands.
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32
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Stöckl M, Herrmann A. Detection of lipid domains in model and cell membranes by fluorescence lifetime imaging microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1444-56. [DOI: 10.1016/j.bbamem.2009.12.015] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 11/30/2009] [Accepted: 12/21/2009] [Indexed: 01/17/2023]
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33
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Oreopoulos J, Epand RF, Epand RM, Yip CM. Peptide-induced domain formation in supported lipid bilayers: direct evidence by combined atomic force and polarized total internal reflection fluorescence microscopy. Biophys J 2010; 98:815-23. [PMID: 20197035 DOI: 10.1016/j.bpj.2009.12.4327] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 11/25/2009] [Accepted: 12/09/2009] [Indexed: 12/01/2022] Open
Abstract
Direct visualization of the mechanism(s) by which peptides induce localized changes to the structure of membranes has high potential for enabling understanding of the structure-function relationship in antimicrobial and cell-penetrating peptides. We have applied a combined imaging strategy to track the interaction of a model antimicrobial peptide, PFWRIRIRR-amide, with bacterial membrane-mimetic supported phospholipid bilayers comprised of POPE/TOCL. Our in situ studies revealed rapid reorganization of the POPE/TOCL membrane into localized TOCL-rich domains with a concomitant change in the organization of the membranes themselves, as reflected by changes in fluorescent-membrane-probe order parameter, upon introduction of the peptide.
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Affiliation(s)
- John Oreopoulos
- Institute of Biomaterials and Biomedical Engineering, Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Ontario, Canada
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34
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Affiliation(s)
- Mikhail Y. Berezin
- Department of Radiology, Washington University School of Medicine, 4525 Scott Ave, St. Louis, USA, Tel. 314-747-0701, 314-362-8599, fax 314-747-5191
| | - Samuel Achilefu
- Department of Radiology, Washington University School of Medicine, 4525 Scott Ave, St. Louis, USA, Tel. 314-747-0701, 314-362-8599, fax 314-747-5191
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35
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Oreopoulos J, Yip CM. Combinatorial microscopy for the study of protein–membrane interactions in supported lipid bilayers: Order parameter measurements by combined polarized TIRFM/AFM. J Struct Biol 2009; 168:21-36. [DOI: 10.1016/j.jsb.2009.02.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 02/23/2009] [Accepted: 02/24/2009] [Indexed: 02/06/2023]
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36
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Boumann HA, Longo ML, Stroeve P, Poolman B, Hopmans EC, Stuart MC, Sinninghe Damsté JS, Schouten S. Biophysical properties of membrane lipids of anammox bacteria: I. Ladderane phospholipids form highly organized fluid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1444-51. [DOI: 10.1016/j.bbamem.2009.04.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2008] [Revised: 04/02/2009] [Accepted: 04/08/2009] [Indexed: 10/20/2022]
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37
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Ariola FS, Li Z, Cornejo C, Bittman R, Heikal AA. Membrane fluidity and lipid order in ternary giant unilamellar vesicles using a new bodipy-cholesterol derivative. Biophys J 2009; 96:2696-708. [PMID: 19348752 DOI: 10.1016/j.bpj.2008.12.3922] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2008] [Revised: 12/11/2008] [Accepted: 12/17/2008] [Indexed: 11/24/2022] Open
Abstract
Cholesterol-rich, liquid-ordered (L(o)) domains are believed to be biologically relevant, and yet detailed knowledge about them, especially in live cells under physiological conditions, is elusive. Although these domains have been observed in model membranes, understanding cholesterol-lipid interactions at the molecular level, under controlled lipid mixing, remains a challenge. Further, although there are a number of fluorescent lipid analogs that partition into liquid-disordered (L(d)) domains, the number of such analogs with a high affinity for biologically relevant L(o) domains is limited. Here, we use a new Bodipy-labeled cholesterol (Bdp-Chol) derivative to investigate membrane fluidity, lipid order, and partitioning in various lipid phases in giant unilamellar vesicles (GUVs) as a model system. GUVs were prepared from mixtures of various molar fractions of dioleoylphosphatidylcholine, cholesterol, and egg sphingomyelin. The L(d) phase domains were also labeled with 1,1'-didodecyl-3,3,3',3'-tetramethylindocarbocyanine (DiI-C(12)) for comparison. Two-photon fluorescence lifetime and anisotropy imaging of Bdp-Chol are sensitive to lipid phase domains in GUVs. The fluorescence lifetime of Bdp-Chol in liquid-disordered, single-phase GUVs is 5.50 +/- 0.08 ns, compared with 4.1 +/- 0.4 ns in the presence of DiI-C(12). The observed reduction of fluorescence lifetime is attributed to Förster resonance energy transfer between Bdp-Chol (a donor) and DiI-C(12) (an acceptor) with an estimated efficiency of 0.25 and donor-acceptor distance of 2.6 +/- 0.2 nm. These results also indicate preferential partitioning (K(p) = 1.88) of Bdp-Chol into the L(o) phase. One-photon, time-resolved fluorescence anisotropy of Bdp-Chol decays as a triexponential in the lipid bilayer with an average rotational diffusion coefficient, lipid order parameter, and membrane fluidity that are sensitive to phase domains. The translational diffusion coefficient of Bdp-Chol, as measured using fluorescence correlation spectroscopy, is (7.4 +/- 0.3) x 10(-8) cm(2)/s and (5.0 +/- 0.2) x 10(-8) cm(2)/s in the L(d) and L(o) phases, respectively. Experimental translational/rotational diffusion coefficient ratios are compared with theoretical predictions using the hydrodynamic model (Saffman-Delbrück). The results suggest that Bdp-Chol is likely to form a complex with other lipid molecules during its macroscopic diffusion in GUV lipid bilayers at room temperature. Our integrated, multiscale results demonstrate the potential of this cholesterol analog for studying lipid-lipid interactions, lipid order, and membrane fluidity of biologically relevant L(o) domains.
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Affiliation(s)
- Florly S Ariola
- Department of Bioengineering, The Pennsylvania State University, University Park, Pennsylvania, USA
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38
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Oreopoulos J, Yip CM. Probing membrane order and topography in supported lipid bilayers by combined polarized total internal reflection fluorescence-atomic force microscopy. Biophys J 2009; 96:1970-84. [PMID: 19254557 DOI: 10.1016/j.bpj.2008.11.041] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Accepted: 11/17/2008] [Indexed: 11/19/2022] Open
Abstract
Determining the local structure, dynamics, and conformational requirements for protein-protein and protein-lipid interactions in membranes is critical to understanding biological processes ranging from signaling to the translocating and membranolytic action of antimicrobial peptides. We report here the application of a combined polarized total internal reflection fluorescence microscopy-in situ atomic force microscopy platform. This platform's ability to image membrane orientational order was demonstrated on DOPC/DSPC/cholesterol model membranes containing the fluorescent membrane probe, DiI-C(20) or BODIPY-PC. Spatially resolved order parameters and fluorophore tilt angles extracted from the polarized total internal reflection fluorescence microscopy images were in good agreement with the topographical details resolved by in situ atomic force microscopy, portending use of this technique for high-resolution characterization of membrane domain structures and peptide-membrane interactions.
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Affiliation(s)
- John Oreopoulos
- Institute of Biomaterials and Biomedical Engineering, Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada
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39
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Tresset G. The multiple faces of self-assembled lipidic systems. PMC BIOPHYSICS 2009; 2:3. [PMID: 19374753 PMCID: PMC2695813 DOI: 10.1186/1757-5036-2-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Accepted: 04/17/2009] [Indexed: 11/10/2022]
Abstract
Lipids, the building blocks of cells, common to every living organisms, have the propensity to self-assemble into well-defined structures over short and long-range spatial scales. The driving forces have their roots mainly in the hydrophobic effect and electrostatic interactions. Membranes in lamellar phase are ubiquitous in cellular compartments and can phase-separate upon mixing lipids in different liquid-crystalline states. Hexagonal phases and especially cubic phases can be synthesized and observed in vivo as well. Membrane often closes up into a vesicle whose shape is determined by the interplay of curvature, area difference elasticity and line tension energies, and can adopt the form of a sphere, a tube, a prolate, a starfish and many more. Complexes made of lipids and polyelectrolytes or inorganic materials exhibit a rich diversity of structural morphologies due to additional interactions which become increasingly hard to track without the aid of suitable computer models. From the plasma membrane of archaebacteria to gene delivery, self-assembled lipidic systems have left their mark in cell biology and nanobiotechnology; however, the underlying physics is yet to be fully unraveled.PACS Codes: 87.14.Cc, 82.70.Uv.
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Affiliation(s)
- Guillaume Tresset
- Laboratoire de Physique des Solides, Université Paris-Sud, CNRS, UMR 8502, F-91405 Orsay Cedex, France.
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40
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Membrane lipid domains and rafts: current applications of fluorescence lifetime spectroscopy and imaging. Chem Phys Lipids 2009; 157:61-77. [DOI: 10.1016/j.chemphyslip.2008.07.011] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Accepted: 07/24/2008] [Indexed: 11/30/2022]
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41
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Two-photon autofluorescence dynamics imaging reveals sensitivity of intracellular NADH concentration and conformation to cell physiology at the single-cell level. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2008; 95:46-57. [PMID: 19179090 DOI: 10.1016/j.jphotobiol.2008.12.010] [Citation(s) in RCA: 181] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 12/17/2008] [Accepted: 12/17/2008] [Indexed: 11/20/2022]
Abstract
Reduced nicotinamide adenine dinucleotide, NADH, is a major electron donor in the oxidative phosphorylation and glycolytic pathways in cells. As a result, there has been recent resurgence in employing intrinsic NADH fluorescence as a natural probe for a range of cellular processes that include apoptosis, cancer pathology, and enzyme kinetics. Here, we report on two-photon fluorescence lifetime and polarization imaging of intrinsic NADH in breast cancer (Hs578T) and normal (Hs578Bst) cells for quantitative analysis of the concentration and conformation (i.e., free-to-enzyme-bound ratios) of this coenzyme. Two-photon fluorescence lifetime imaging of intracellular NADH indicates sensitivity to both cell pathology and inhibition of the respiratory chain activities using potassium cyanide (KCN). Using a newly developed non-invasive assay, we estimate the average NADH concentration in cancer cells (168+/-49 microM) to be approximately 1.8-fold higher than in breast normal cells (99+/-37 microM). Such analyses indicate changes in energy metabolism and redox reactions in normal breast cells upon inhibition of the respiratory chain activity using KCN. In addition, time-resolved associated anisotropy of cellular autofluorescence indicates population fractions of free (0.18+/-0.08) and enzyme-bound (0.82+/-0.08) conformations of intracellular NADH in normal breast cells. These fractions are statistically different from those in breast cancer cells (free: 0.25+/-0.08; bound: 0.75+/-0.08). Comparative studies on the binding kinetics of NADH with mitochondrial malate dehydrogenase and lactate dehydrogenase in solution mimic our findings in living cells. These quantitative studies demonstrate the potential of intracellular NADH dynamics (rather than intensity) imaging for probing mitochondrial anomalies associated with neurodegenerative diseases, cancer, diabetes, and aging. Our approach is also applicable to other metabolic and signaling pathways in living cells, without the need for cell destruction as in conventional biochemical assays.
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42
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Combining fluorescence lifetime and polarization microscopy to discriminate phase separated domains in giant unilamellar vesicles. Biophys J 2008; 95:5737-47. [PMID: 18790852 DOI: 10.1529/biophysj.108.131490] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Using fluorescence lifetime microscopy we study the structure of lipid domains in giant unilamellar vesicles made from sphingomyelin, 1,2-dioleoyl-sn-glycero-3-phosphocholine, and cholesterol. Lifetimes and orientation of a derivative of the fluorescent probe DPH embedded in the membrane were measured for binary and ternary lipid mixtures incorporating up to 42 mol % of cholesterol. The results show that adding cholesterol always increases the lifetime of the probe studied. In addition, the analysis of the probe orientation indicates that cholesterol has little influence on the ordering of the sphingomyelin alkyl chains whereas it has a noticeable effect on the structure of the 1,2-dioleoyl-sn-glycero-3-phosphocholine chains. The measurements made on the orientation and lifetime of the probe show the structure of the membrane in its liquid ordered and liquid disordered domains.
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Yu Q, Proia M, Heikal AA. Integrated biophotonics approach for noninvasive and multiscale studies of biomolecular and cellular biophysics. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:041315. [PMID: 19021323 DOI: 10.1117/1.2952297] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In the crowded cellular milieu, biological processes require coordinated intermolecular interactions, conformational changes, and molecular transport that span a wide range of spatial and temporal scales. This complexity requires an integrated, noninvasive, multiscale experimental approach. Here, we develop a multimodal fluorescence microspectroscopy system, integrated on a single platform, to gain information about molecular interactions and their dynamics with high spatio-temporal resolution. To demonstrate the versatility of our experimental approach, we use rhodamine 123-labeled mitochondria in breast cancer cells (Hs578T), verified using differential interference contrast (DIC) and fluorescence (confocal and two-photon) microscopy, as a model system. We develop an assay to convert fluorescence intensity to actual concentrations in intact, individual living cells, which contrasts with conventional biochemical techniques that require cell lysates. In this assay, we employ two-photon fluorescence lifetime imaging microscopy (FLIM) to quantify the fluorescence quantum yield variations found within individual cells. Functionally driven changes in cell environment, molecular conformation, and rotational diffusion are investigated using fluorescence polarization anisotropy imaging. Moreover, we quantify translational diffusion and chemical kinetics of large molecular assemblies using fluorescence correlation spectroscopy. Our integrated approach can be applied to a wide range of molecular and cellular processes, such as receptor-mediated signaling and metabolic activation.
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Affiliation(s)
- Qianru Yu
- Pennsylvania State University, Department of Bioengineering, 205 Hallowell Building, University Park, Pennsylvania 16802, USA
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44
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Gullapalli RR, Demirel MC, Butler PJ. Molecular dynamics simulations of DiI-C18(3) in a DPPC lipid bilayer. Phys Chem Chem Phys 2008; 10:3548-60. [PMID: 18548161 DOI: 10.1039/b716979e] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We performed a 40 ns simulation of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI-C18(3)) in a 1,2-dipalmitoyl-sn-glycero-3-phosphatidyl choline (DPPC) bilayer in order to facilitate interpretation of lipid dynamics and membrane structure from fluorescence lifetime, anisotropy, and fluorescence correlations spectroscopy (FCS). Incorporation of DiI of 1.6 to 3.2 mol% induced negligible changes in area per lipid but detectable increases in bilayer thickness, each of which are indicators of membrane structural perturbation. The DiI chromophore angle was 77 +/- 17 degrees with respect to the bilayer normal, consistent with rotational diffusion inferred from polarization studies. The DiI headgroup was located 0.63 nm below the lipid head group-water interface, a novel result in contrast to some popular cartoon representations of DiI but consistent with DiI's increase in quantum yield when incorporated into lipid bilayers. Importantly, the fast component of rotational anisotropy matched published experimental results demonstrating that sufficient free volume exists at the sub-interfacial region to support fast rotations. Simulations with non-charged DiI head groups exhibited DiI flip-flop, demonstrating that the positively-charged chromophore stabilizes the orientation and location of DiI in a single monolayer. DiI induced detectable changes in interfacial properties of water ordering, electrostatic potential, and changes in P-N vector orientation of DPPC lipids. The diffusion coefficient of DiI (9.7 +/- 0.02 x 10(-8) cm2 s(-1)) was similar to the diffusion of DPPC molecules (10.7 +/- 0.04 x 10(-8) cm2 s(-1)), supporting the conclusion that DiI dynamics reflect lipid dynamics. These results provide the first atomistic level insight into DiI dynamics, results essential in elucidating lipid dynamics through single molecule fluorescence studies.
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Affiliation(s)
- Ramachandra R Gullapalli
- Department of Bioengineering, The Pennsylvania State University, 228 Hallowell Building, University Park, PA 16802, USA
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Davey AM, Krise KM, Sheets ED, Heikal AA. Molecular Perspective of Antigen-mediated Mast Cell Signaling. J Biol Chem 2008; 283:7117-27. [DOI: 10.1074/jbc.m708879200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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46
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Davey AM, Walvick RP, Liu Y, Heikal AA, Sheets ED. Membrane order and molecular dynamics associated with IgE receptor cross-linking in mast cells. Biophys J 2006; 92:343-55. [PMID: 17040981 PMCID: PMC1697873 DOI: 10.1529/biophysj.106.088815] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cholesterol-rich microdomains (or "lipid rafts") within the plasma membrane have been hypothesized to exist in a liquid-ordered phase and play functionally important roles in cell signaling; however, these microdomains defy detection using conventional imaging. To visualize domains and relate their nanostructure and dynamics to mast cell signaling, we use two-photon (760 nm and 960 nm) fluorescence lifetime imaging microscopy and fluorescence polarization anisotropy imaging, with comparative one-photon anisotropy imaging and single-point lifetime and anisotropy decay measurements. The inherent sensitivity of ultrafast excited-state dynamics and rotational diffusion to the immediate surroundings of a fluorophore allows for real-time monitoring of membrane structure and organization. When the high affinity receptor for IgE (FcepsilonRI) is extensively cross-linked with anti-IgE, molecules associated with cholesterol-rich microdomains (e.g., saturated lipids (the lipid analog diI-C(18) or glycosphingolipids)) and lipid-anchored proteins coredistribute with cross-linked IgE-FcepsilonRI. We find an enhancement in fluorescence lifetime and anisotropy of diI-C(18) and Alexa 488-labeled IgE-FcepsilonRI in the domains where these molecules colocalize. Our results suggest that fluorescence lifetime and, particularly, anisotropy permit us to correlate the recruitment of lipid molecules into more ordered domains that serve as platforms for IgE-mediated signaling.
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Affiliation(s)
- Angel M Davey
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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