1
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Schirripa Spagnolo C, Luin S. Impact of temporal resolution in single particle tracking analysis. Discov Nano 2024; 19:87. [PMID: 38724858 PMCID: PMC11082114 DOI: 10.1186/s11671-024-04029-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 04/29/2024] [Indexed: 05/12/2024]
Abstract
Temporal resolution is a key parameter in the observation of dynamic processes, as in the case of single molecules motions visualized in real time in two-dimensions by wide field (fluorescence) microscopy, but a systematic investigation of its effects in all the single particle tracking analysis steps is still lacking. Here we present tools to quantify its impact on the estimation of diffusivity and of its distribution using one of the most popular tracking software for biological applications on simulated data and movies. We found important shifts and different widths for diffusivity distributions, depending on the interplay of temporal sampling conditions with various parameters, such as simulated diffusivity, density of spots, signal-to-noise ratio, lengths of trajectories, and kind of boundaries in the simulation. We examined conditions starting from the ones of experiments on the fluorescently labelled receptor p75NTR, a relatively fast-diffusing membrane receptor (diffusivity around 0.5-1 µm2/s), visualized by TIRF microscopy on the basal membrane of living cells. From the analysis of the simulations, we identified the best conditions in cases similar to these ones; considering also the experiments, we could confirm a range of values of temporal resolution suitable for obtaining reliable diffusivity results. The procedure we present can be exploited in different single particle/molecule tracking applications to find an optimal temporal resolution.
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Affiliation(s)
| | - Stefano Luin
- NEST Laboratory, Scuola Normale Superiore, Piazza San Silvestro 12, 56127, Pisa, Italy.
- NEST Laboratory, Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127, Pisa, Italy.
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2
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Collier CP, Bolmatov D, Elkins JG, Katsaras J. Nanoscopic lipid domains determined by microscopy and neutron scattering. Methods 2024; 223:127-135. [PMID: 38331125 DOI: 10.1016/j.ymeth.2024.01.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 01/22/2024] [Accepted: 01/26/2024] [Indexed: 02/10/2024] Open
Abstract
Biological membranes are highly complex supramolecular assemblies, which play central roles in biology. However, their complexity makes them challenging to study their nanoscale structures. To overcome this challenge, model membranes assembled using reduced sets of membrane-associated biomolecules have been found to be both excellent and tractable proxies for biological membranes. Due to their relative simplicity, they have been studied using a range of biophysical characterization techniques. In this review article, we will briefly detail the use of fluorescence and electron microscopies, and X-ray and neutron scattering techniques used over the past few decades to study the nanostructure of biological membranes.
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Affiliation(s)
- Charles P Collier
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Dima Bolmatov
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA; Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - James G Elkins
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - John Katsaras
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA; Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Neutron Scattering Division, Oak Ridge National Laboratorry, Oak Ridege, TN, USA
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3
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Woodward X, Javanainen M, Fábián B, Kelly CV. Nanoscale membrane curvature sorts lipid phases and alters lipid diffusion. Biophys J 2023:S0006-3495(23)00001-2. [PMID: 36604961 DOI: 10.1016/j.bpj.2023.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 11/23/2022] [Accepted: 01/03/2023] [Indexed: 01/06/2023] Open
Abstract
The precise spatiotemporal control of nanoscale membrane shape and composition is the result of a complex interplay of individual and collective molecular behaviors. Here, we employed single-molecule localization microscopy and computational simulations to observe single-lipid diffusion and sorting in model membranes with varying compositions, phases, temperatures, and curvatures. Supported lipid bilayers were created over 50-nm-radius nanoparticles to mimic the size of naturally occurring membrane buds, such as endocytic pits and the formation of viral envelopes. The curved membranes recruited liquid-disordered lipid phases while altering the diffusion and sorting of tracer lipids. Disorder-preferring fluorescent lipids sorted to and experienced faster diffusion on the nanoscale curvature only when embedded in a membrane capable of sustaining lipid phase separation at low temperatures. The curvature-induced sorting and faster diffusion even occurred when the sample temperature was above the miscibility temperature of the planar membrane, implying that the nanoscale curvature could induce phase separation in otherwise homogeneous membranes. Further confirmation and understanding of these results are provided by continuum and coarse-grained molecular dynamics simulations with explicit and spontaneous curvature-phase coupling, respectively. The curvature-induced membrane compositional heterogeneity and altered dynamics were achieved only with a coupling of the curvature with a lipid phase separation. These cross-validating results demonstrate the complex interplay of lipid phases, molecular diffusion, and nanoscale membrane curvature that are critical for membrane functionality.
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Affiliation(s)
- Xinxin Woodward
- Department of Physics and Astronomy, Wayne State University, Detroit, Michigan
| | - Matti Javanainen
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic; Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Balázs Fábián
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Christopher V Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, Michigan.
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4
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Chai YJ, Cheng CY, Liao YH, Lin CH, Hsieh CL. Heterogeneous nanoscopic lipid diffusion in the live cell membrane and its dependency on cholesterol. Biophys J 2022; 121:3146-3161. [PMID: 35841144 PMCID: PMC9463655 DOI: 10.1016/j.bpj.2022.07.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 03/08/2022] [Accepted: 07/06/2022] [Indexed: 11/02/2022] Open
Abstract
Cholesterol plays a unique role in the regulation of membrane organization and dynamics by modulating the membrane phase transition at the nanoscale. Unfortunately, due to their small sizes and dynamic nature, the effects of cholesterol-mediated membrane nanodomains on membrane dynamics remain elusive. Here, using ultrahigh-speed single-molecule tracking with advanced optical microscope techniques, we investigate the diffusive motion of single phospholipids in the live cell plasma membrane at the nanoscale and its dependency on the cholesterol concentration. We find that both saturated and unsaturated phospholipids undergo anomalous subdiffusion on the length scale of 10-100 nm. The diffusion characteristics exhibit considerable variations in space and in time, indicating that the nanoscopic lipid diffusion is highly heterogeneous. Importantly, through the statistical analysis, apparent dual-mobility subdiffusion is observed from the mixed diffusion behaviors. The measured subdiffusion agrees well with the hop diffusion model that represents a diffuser moving in a compartmentalized membrane created by the cytoskeleton meshwork. Cholesterol depletion diminishes the lipid mobility with an apparently smaller compartment size and a stronger confinement strength. Similar results are measured with temperature reduction, suggesting that the more heterogeneous and restricted diffusion is connected to the nanoscopic membrane phase transition. Our conclusion supports the model that cholesterol depletion induces the formation of gel-phase, solid-like membrane nanodomains. These nanodomains undergo restricted diffusion and act as diffusion obstacles to the membrane molecules that are excluded from the nanodomains. This work provides the experimental evidence that the nanoscopic lipid diffusion in the cell plasma membrane is heterogeneous and sensitive to the cholesterol concentration and temperature, shedding new light on the regulation mechanisms of nanoscopic membrane dynamics.
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Affiliation(s)
- Yu-Jo Chai
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan
| | - Ching-Ya Cheng
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan
| | - Yi-Hung Liao
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan
| | - Chih-Hsiang Lin
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan
| | - Chia-Lung Hsieh
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan.
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5
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Steindel M, Orsine de Almeida I, Strawbridge S, Chernova V, Holcman D, Ponjavic A, Basu S. Studying the Dynamics of Chromatin-Binding Proteins in Mammalian Cells Using Single-Molecule Localization Microscopy. Methods Mol Biol 2022; 2476:209-247. [PMID: 35635707 DOI: 10.1007/978-1-0716-2221-6_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Single-molecule localization microscopy (SMLM) allows the super-resolved imaging of proteins within mammalian nuclei at spatial resolutions comparable to that of a nucleosome itself (~20 nm). The technique is therefore well suited to the study of chromatin structure. Fixed-cell SMLM has already allowed temporal "snapshots" of how proteins are arranged on chromatin within mammalian nuclei. In this chapter, we focus on how recent developments, for example in selective plane illumination, 3D SMLM, and protein labeling, have led to a range of live-cell SMLM studies. We describe how to carry out single-particle tracking (SPT) of single proteins and, by analyzing their diffusion parameters, how to determine whether proteins interact with chromatin, diffuse freely, or do both. We can study the numbers of proteins that interact with chromatin and also determine their residence time on chromatin. We can determine whether these proteins form functional clusters within the nucleus as well as whether they form specific nuclear structures.
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Affiliation(s)
- Maike Steindel
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | | | - Stanley Strawbridge
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Valentyna Chernova
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - David Holcman
- Group of Computational Biology and Applied Mathematics, Institute of Biology, Ecole Normale Supérieure, Paris, France
| | - Aleks Ponjavic
- School of Physics and Astronomy and School of Food Science and Nutrition, University of Leeds, Leeds, UK.
| | - Srinjan Basu
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK.
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6
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Wi JH, Heo CH, Gwak H, Jung C, Kim SY. Probing Physical Properties of the Cellular Membrane in Senescent Cells by Fluorescence Imaging. J Phys Chem B 2021; 125:10182-10194. [PMID: 34473497 DOI: 10.1021/acs.jpcb.1c05403] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Cellular senescence is the irreversible cell cycle arrest in response to various types of stress. Although the plasma membrane and its composition are significantly affected by cellular senescence, detailed studies on the physical properties of the plasma membrane have shown inconclusive results. In this study, we utilized both ensemble and single-molecule fluorescence imaging to investigate how membrane properties, such as fluidity, hydrophobicity, and ganglioside GM1 level are affected by cellular senescence. The diffusion coefficient of lipid probes, as well as the type of diffusion determined by an exponent α, which is the slope of the log-log plot of mean squared displacement as a function of time lag, were analyzed. We found that the number of molecules with a lower diffusion coefficient increased as cells became senescent. The changes in the population with a lower diffusion coefficient, observed after methyl-β-cyclodextrin treatment, and the increase in ceramide levels, detected using a ceramide-specific antibody, suggest that ceramide-rich lipid rafts were enhanced in senescent cells. Our results emphasize the importance of membrane properties in cellular senescence and might serve as a base for in-depth studies to determine how such domains facilitate the signaling pathway specific to cellular senescence.
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Affiliation(s)
- Ji Hun Wi
- Theragnosis Research Center, Biomedical Research Division, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea.,Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02792, Republic of Korea
| | - Cheol Ho Heo
- Theragnosis Research Center, Biomedical Research Division, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea
| | - HyeRan Gwak
- Theragnosis Research Center, Biomedical Research Division, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea
| | - Cheulhee Jung
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02792, Republic of Korea
| | - So Yeon Kim
- Theragnosis Research Center, Biomedical Research Division, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea.,Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul 02792, Republic of Korea
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7
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Reina F, Wigg JM, Dmitrieva M, Vogler B, Lefebvre J, Rittscher J, Eggeling C. TRAIT2D: a Software for Quantitative Analysis of Single Particle Diffusion Data. F1000Res 2021; 10:838. [PMID: 35186271 PMCID: PMC8829092 DOI: 10.12688/f1000research.54788.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/25/2022] [Indexed: 11/20/2022] Open
Abstract
Single particle tracking (SPT) is one of the most widely used tools in optical microscopy to evaluate particle mobility in a variety of situations, including cellular and model membrane dynamics. Recent technological developments, such as Interferometric Scattering microscopy, have allowed recording of long, uninterrupted single particle trajectories at kilohertz framerates. The resulting data, where particles are continuously detected and do not displace much between observations, thereby do not require complex linking algorithms. Moreover, while these measurements offer more details into the short-term diffusion behaviour of the tracked particles, they are also subject to the influence of localisation uncertainties, which are often underestimated by conventional analysis pipelines. we thus developed a Python library, under the name of TRAIT2D (Tracking Analysis Toolbox - 2D version), in order to track particle diffusion at high sampling rates, and analyse the resulting trajectories with an innovative approach. The data analysis pipeline introduced is more localisation-uncertainty aware, and also selects the most appropriate diffusion model for the data provided on a statistical basis. A trajectory simulation platform also allows the user to handily generate trajectories and even synthetic time-lapses to test alternative tracking algorithms and data analysis approaches. A high degree of customisation for the analysis pipeline, for example with the introduction of different diffusion modes, is possible from the source code. Finally, the presence of graphical user interfaces lowers the access barrier for users with little to no programming experience.
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Affiliation(s)
- Francesco Reina
- Leibniz-Institut für Photonische Technologien e.V, Jena, Germany
| | - John M.A. Wigg
- Institute of Applied Optics and Biophysics, Friedrich-Schiller-Universität, Jena, Germany
| | - Mariia Dmitrieva
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Bela Vogler
- Institute of Applied Optics and Biophysics, Friedrich-Schiller-Universität, Jena, Germany
| | - Joël Lefebvre
- Département d'informatique, University of Quebec at Montreal, Montreal, Canada
| | - Jens Rittscher
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Christian Eggeling
- Leibniz-Institut für Photonische Technologien e.V, Jena, Germany
- Institute of Applied Optics and Biophysics, Friedrich-Schiller-Universität, Jena, Germany
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
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8
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Abstract
Single particle tracking (SPT) is one of the most widely used tools in optical microscopy to evaluate particle mobility in a variety of situations, including cellular and model membrane dynamics. Recent technological developments, such as Interferometric Scattering microscopy, have allowed recording of long, uninterrupted single particle trajectories at kilohertz framerates. The resulting data, where particles are continuously detected and do not displace much between observations, thereby do not require complex linking algorithms. Moreover, while these measurements offer more details into the short-term diffusion behaviour of the tracked particles, they are also subject to the influence of localisation uncertainties, which are often underestimated by conventional analysis pipelines. we thus developed a Python library, under the name of TRAIT2D (Tracking Analysis Toolbox - 2D version), in order to track particle diffusion at high sampling rates, and analyse the resulting trajectories with an innovative approach. The data analysis pipeline introduced is more localisation-uncertainty aware, and also selects the most appropriate diffusion model for the data provided on a statistical basis. A trajectory simulation platform also allows the user to handily generate trajectories and even synthetic time-lapses to test alternative tracking algorithms and data analysis approaches. A high degree of customisation for the analysis pipeline, for example with the introduction of different diffusion modes, is possible from the source code. Finally, the presence of graphical user interfaces lowers the access barrier for users with little to no programming experience.
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Affiliation(s)
- Francesco Reina
- Leibniz-Institut für Photonische Technologien e.V, Jena, Germany
| | - John M.A. Wigg
- Institute of Applied Optics and Biophysics, Friedrich-Schiller-Universität, Jena, Germany
| | - Mariia Dmitrieva
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Bela Vogler
- Institute of Applied Optics and Biophysics, Friedrich-Schiller-Universität, Jena, Germany
| | - Joël Lefebvre
- Département d'informatique, University of Quebec at Montreal, Montreal, Canada
| | - Jens Rittscher
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Christian Eggeling
- Leibniz-Institut für Photonische Technologien e.V, Jena, Germany
- Institute of Applied Optics and Biophysics, Friedrich-Schiller-Universität, Jena, Germany
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
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9
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Urbančič I, Schiffelers L, Jenkins E, Gong W, Santos AM, Schneider F, O'Brien-Ball C, Vuong MT, Ashman N, Sezgin E, Eggeling C. Aggregation and mobility of membrane proteins interplay with local lipid order in the plasma membrane of T cells. FEBS Lett 2021; 595:2127-2146. [PMID: 34160065 DOI: 10.1002/1873-3468.14153] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 06/07/2021] [Accepted: 06/18/2021] [Indexed: 01/17/2023]
Abstract
To disentangle the elusive lipid-protein interactions in T-cell activation, we investigate how externally imposed variations in mobility of key membrane proteins (T-cell receptor [TCR], kinase Lck, and phosphatase CD45) affect the local lipid order and protein colocalisation. Using spectral imaging with polarity-sensitive membrane probes in model membranes and live Jurkat T cells, we find that partial immobilisation of proteins (including TCR) by aggregation or ligand binding changes their preference towards a more ordered lipid environment, which can recruit Lck. Our data suggest that the cellular membrane is poised to modulate the frequency of protein encounters upon alterations of their mobility, for example in ligand binding, which offers new mechanistic insight into the involvement of lipid-mediated interactions in membrane-hosted signalling events.
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Affiliation(s)
- Iztok Urbančič
- MRC Weatherall Institute of Molecular Medicine, University of Oxford, UK
- Jožef Stefan Institute, Ljubljana, Slovenia
| | - Lisa Schiffelers
- MRC Weatherall Institute of Molecular Medicine, University of Oxford, UK
| | - Edward Jenkins
- MRC Weatherall Institute of Molecular Medicine, University of Oxford, UK
| | - Weijian Gong
- MRC Weatherall Institute of Molecular Medicine, University of Oxford, UK
| | - Ana Mafalda Santos
- MRC Weatherall Institute of Molecular Medicine, University of Oxford, UK
| | - Falk Schneider
- MRC Weatherall Institute of Molecular Medicine, University of Oxford, UK
| | | | - Mai Tuyet Vuong
- MRC Weatherall Institute of Molecular Medicine, University of Oxford, UK
| | - Nicole Ashman
- MRC Weatherall Institute of Molecular Medicine, University of Oxford, UK
| | - Erdinc Sezgin
- MRC Weatherall Institute of Molecular Medicine, University of Oxford, UK
- Science for Life Laboratory, Karolinska Institutet, Solna, Sweden
| | - Christian Eggeling
- MRC Weatherall Institute of Molecular Medicine, University of Oxford, UK
- Institute of Applied Optics and Biophysics, Friedrich-Schiller-University Jena, Germany
- Leibniz Institute of Photonic Technology e.V., Jena, Germany
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10
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Wang Z, Wang X, Zhang Y, Xu W, Han X. Principles and Applications of Single Particle Tracking in Cell Research. Small 2021; 17:e2005133. [PMID: 33533163 DOI: 10.1002/smll.202005133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/24/2020] [Indexed: 06/12/2023]
Abstract
It is a tough challenge for many decades to decipher the complex relationships between cell behaviors and cellular physical properties. Single particle tracking (SPT) with high spatial and temporal resolution has been applied extensively in cell research to understand physicochemical properties of cells and their bio-functions by tracking endogenous or exogenous probes. This review describes the fundamental principles of SPT as well as its applications in intracellular mechanics, membrane dynamics, organelles distribution, and processes of internalization and transport. Finally, challenges and future directions of SPT are also discussed.
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Affiliation(s)
- Zhao Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, China
| | - Xuejing Wang
- College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, 310058, China
| | - Ying Zhang
- School of Materials and Chemical Engineering, Heilongjiang Institute of Technology, Harbin, 150027, China
| | - Weili Xu
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, China
| | - Xiaojun Han
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, China
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11
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Batta G, Hajdu T, Nagy P. Characterization of the Effect of Sphingolipid Accumulation on Membrane Compactness, Dipole Potential, and Mobility of Membrane Components. Methods Mol Biol 2021; 2187:283-301. [PMID: 32770513 DOI: 10.1007/978-1-0716-0814-2_16] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Communication between cells and their environment is carried out through the plasma membrane including the action of most pharmaceutical drugs. Although such a communication typically involves specific binding of a messenger to a membrane receptor, the biophysical state of the lipid bilayer strongly influences the outcome of this interaction. Sphingolipids constitute an important part of the lipid membrane, and their mole fraction modifies the biophysical characteristics of the membrane. Here, we describe methods that can be used for measuring how sphingolipid accumulation alters the compactness, microviscosity, and dipole potential of the lipid bilayer and the mobility of membrane components.
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Affiliation(s)
- Gyula Batta
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Tímea Hajdu
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Doctoral School of Molecular Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Peter Nagy
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
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12
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Woodward X, Kelly CV. Single-lipid dynamics in phase-separated supported lipid bilayers. Chem Phys Lipids 2020; 233:104991. [PMID: 33121937 DOI: 10.1016/j.chemphyslip.2020.104991] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 10/02/2020] [Accepted: 10/06/2020] [Indexed: 11/26/2022]
Abstract
Phase separation is a fundamental organizing mechanism on cellular membranes. Lipid phases have complex dependencies on the membrane composition, curvature, tension, and temperature. Lipid diffusion rates vary by up to ten-fold between liquid-disordered (Ld) and liquid-ordered (Lo) phases depending on the membrane composition, measurement technique, and the surrounding environment. This manuscript reports the lipid diffusion on phase-separated supported lipid bilayers (SLBs) with varying temperature, composition, and lipid phase. Lipid diffusion is measured by single-particle tracking (SPT) and fluorescence correlation spectroscopy (FCS) via custom data acquisition and analysis protocols that apply to diverse membranes systems. Traditionally, SPT is sensitive to diffuser aggregation, whereas the diffusion rates reported by FCS are unaffected by the presence of immobile aggregates. Within this manuscript, we report (1) improved single-particle tracking analysis of lipid diffusion, (2) comparison and consistency between diffusion measurement methods for non-Brownian diffusers, and (3) the application of these methods to measure the phase, temperature, and composition dependencies in lipid diffusion. We demonstrate improved SPT analysis methods that yield consistent FCS and SPT diffusion results even when most fluorescent lipids are frequently confined within aggregates within the membrane. With varying membrane composition and temperature, we demonstrate differences in diffusion between the Ld and Lo phases of SLBs.
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Affiliation(s)
- Xinxin Woodward
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, United States
| | - Christopher V Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, United States.
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13
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Kalappurakkal JM, Sil P, Mayor S. Toward a new picture of the living plasma membrane. Protein Sci 2020; 29:1355-1365. [PMID: 32297381 DOI: 10.1002/pro.3874] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/13/2020] [Accepted: 04/14/2020] [Indexed: 01/08/2023]
Abstract
Our understanding of the plasma membrane structure has undergone a major change since the proposal of the fluid mosaic model of Singer and Nicholson in the 1970s. In this model, the membrane, composed of over thousand lipid and protein species, is organized as a well-equilibrated two-dimensional fluid. Here, the distribution of lipids is largely expected to reflect a multicomponent system, and proteins are expected to be surrounded by an annulus of specialized lipid species. With the recognition that a multicomponent lipid membrane is capable of phase segregation, the membrane is expected to appear as patchwork quilt pattern of membrane domains. However, the constituents of a living membrane are far from being well equilibrated. The living cell membrane actively maintains a trans-bilayer asymmetry of composition, and its constituents are subject to a number of dynamic processes due to synthesis, lipid transfer as well as membrane traffic and turnover. Moreover, membrane constituents engage with the dynamic cytoskeleton of a living cell, and are both passively as well as actively manipulated by this engagement. The extracellular matrix and associated elements also interact with membrane proteins contributing to another layer of interaction. At the nano- and mesoscale, the organization of lipids and proteins emerge from these encounters, as well as from protein-protein, protein-lipid, and lipid-lipid interactions in the membrane. New methods to study the organization of membrane components at these scales have also been developed, and provide an opportunity to synthesize a new picture of the living cell surface as an active membrane composite.
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Affiliation(s)
- Joseph Mathew Kalappurakkal
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka, India
| | - Parijat Sil
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka, India
| | - Satyajit Mayor
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka, India
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14
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Jacobson K, Liu P, Lagerholm BC. The Lateral Organization and Mobility of Plasma Membrane Components. Cell 2020; 177:806-819. [PMID: 31051105 DOI: 10.1016/j.cell.2019.04.018] [Citation(s) in RCA: 136] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 02/01/2019] [Accepted: 04/09/2019] [Indexed: 01/22/2023]
Abstract
Over the last several decades, an impressive array of advanced microscopic and analytical tools, such as single-particle tracking and nanoscopic fluorescence correlation spectroscopy, has been applied to characterize the lateral organization and mobility of components in the plasma membrane. Such analysis can tell researchers about the local dynamic composition and structure of membranes and is important for predicting the outcome of membrane-based reactions. However, owing to the unresolved complexity of the membrane and the structures peripheral to it, identification of the detailed molecular origin of the interactions that regulate the organization and mobility of the membrane has not proceeded quickly. This Perspective presents an overview of how cell-surface structure may give rise to the types of lateral mobility that are observed and some potentially fruitful future directions to elucidate the architecture of these structures in more molecular detail.
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Affiliation(s)
- Ken Jacobson
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Ping Liu
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, 430074 Hubei, China
| | - B Christoffer Lagerholm
- Wolfson Imaging Centre Oxford, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford OX3 9DS, UK
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15
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Abstract
The spatial organization of molecules in cell membranes and their dynamic interactions play a central role in regulating cell functions. Single-particle tracking (SPT), a technique in which single molecules are imaged and tracked in real time, has led to breakthrough discoveries regarding these spatiotemporal complexities of cell membranes. There are, however, emerging concerns about factors that might produce misleading interpretations of SPT results. Here, we briefly review the application of SPT to understanding the nanoscale heterogeneities of plasma membranes, with a focus on the unique challenges, pitfalls, and limitations that confront the use of nanoparticles as imaging probes for tracking the dynamics of single molecules in cell membranes.
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16
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de Wit G, Albrecht D, Ewers H, Kukura P. Revealing Compartmentalized Diffusion in Living Cells with Interferometric Scattering Microscopy. Biophys J 2019; 114:2945-2950. [PMID: 29925030 DOI: 10.1016/j.bpj.2018.05.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 04/08/2018] [Accepted: 05/02/2018] [Indexed: 12/19/2022] Open
Abstract
The spatiotemporal organization and dynamics of the plasma membrane and its constituents are central to cellular function. Fluorescence-based single-particle tracking has emerged as a powerful approach for studying the single molecule behavior of plasma-membrane-associated events because of its excellent background suppression, at the expense of imaging speed and observation time. Here, we show that interferometric scattering microscopy combined with 40 nm gold nanoparticle labeling can be used to follow the motion of membrane proteins in the plasma membrane of live cultured mammalian cell lines and hippocampal neurons with up to 3 nm precision and 25 μs temporal resolution. The achievable spatiotemporal precision enabled us to reveal signatures of compartmentalization in neurons likely caused by the actin cytoskeleton.
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Affiliation(s)
- Gabrielle de Wit
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, United Kingdom
| | - David Albrecht
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Helge Ewers
- Department of Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Philipp Kukura
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, United Kingdom.
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17
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Nicovich PR, Kwiatek JM, Ma Y, Benda A, Gaus K. FSCS Reveals the Complexity of Lipid Domain Dynamics in the Plasma Membrane of Live Cells. Biophys J 2019; 114:2855-2864. [PMID: 29925022 PMCID: PMC6026469 DOI: 10.1016/j.bpj.2018.04.050] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 02/14/2018] [Accepted: 04/10/2018] [Indexed: 12/14/2022] Open
Abstract
The coexistence of lipid domains with different degrees of lipid packing in the plasma membrane of mammalian cells has been postulated, but direct evidence has so far been challenging to obtain because of the small size and short lifetime of these domains in live cells. Here, we use fluorescence spectral correlation spectroscopy in conjunction with a probe sensitive to the membrane environment to quantify spectral fluctuations associated with dynamics of membrane domains in live cells. With this method, we show that membrane domains are present in live COS-7 cells and have a lifetime lower bound of 5.90 and 14.69 ms for the ordered and disordered phases, respectively. Comparisons to simulations indicate that the underlying mechanism of these fluctuations is complex but qualitatively described by a combination of dye diffusion between membrane domains as well as the motion of domains within the membrane.
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Affiliation(s)
- Philip R Nicovich
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, Sydney, New South Wales, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, New South Wales, Australia; Allen Institute for Brain Science, Seattle, Washington.
| | - Joanna M Kwiatek
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, Sydney, New South Wales, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, New South Wales, Australia
| | - Yuanqing Ma
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, Sydney, New South Wales, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, New South Wales, Australia
| | - Aleš Benda
- Imaging Methods Core Facility at BIOCEV, Faculty of Sciences, Charles University, Vestec, Czech Republic
| | - Katharina Gaus
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, Sydney, New South Wales, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, New South Wales, Australia
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18
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Pinkwart K, Schneider F, Lukoseviciute M, Sauka-Spengler T, Lyman E, Eggeling C, Sezgin E. Nanoscale dynamics of cholesterol in the cell membrane. J Biol Chem 2019; 294:12599-12609. [PMID: 31270209 PMCID: PMC6709632 DOI: 10.1074/jbc.ra119.009683] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 06/26/2019] [Indexed: 12/22/2022] Open
Abstract
Cholesterol constitutes ∼30-40% of the mammalian plasma membrane, a larger fraction than of any other single component. It is a major player in numerous signaling processes as well as in shaping molecular membrane architecture. However, our knowledge of the dynamics of cholesterol in the plasma membrane is limited, restricting our understanding of the mechanisms regulating its involvement in cell signaling. Here, we applied advanced fluorescence imaging and spectroscopy approaches on in vitro (model membranes) and in vivo (live cells and embryos) membranes as well as in silico analysis to systematically study the nanoscale dynamics of cholesterol in biological membranes. Our results indicate that cholesterol diffuses faster than phospholipids in live membranes, but not in model membranes. Interestingly, a detailed statistical diffusion analysis suggested two-component diffusion for cholesterol in the plasma membrane of live cells. One of these components was similar to a freely diffusing phospholipid analogue, whereas the other one was significantly faster. When a cholesterol analogue was localized to the outer leaflet only, the fast diffusion of cholesterol disappeared, and it diffused similarly to phospholipids. Overall, our results suggest that cholesterol diffusion in the cell membrane is heterogeneous and that this diffusional heterogeneity is due to cholesterol's nanoscale interactions and localization in the membrane.
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Affiliation(s)
- Kerstin Pinkwart
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom
| | - Falk Schneider
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom
| | - Martyna Lukoseviciute
- Radcliffe Department of Medicine, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom
| | - Tatjana Sauka-Spengler
- Radcliffe Department of Medicine, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom
| | - Edward Lyman
- Departments of Physics and Astronomy and Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716
| | - Christian Eggeling
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom.,Institute of Applied Optics and Biophysics, Friedrich-Schiller-University Jena, Max-Wien Platz 4, 07743 Jena, Germany.,Leibniz Institute of Photonic Technology e.V., Albert-Einstein-Straße 9, 07745 Jena, Germany
| | - Erdinc Sezgin
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom
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19
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Enoki TA, Heberle FA, Feigenson GW. FRET Detects the Size of Nanodomains for Coexisting Liquid-Disordered and Liquid-Ordered Phases. Biophys J 2019; 114:1921-1935. [PMID: 29694869 DOI: 10.1016/j.bpj.2018.03.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 02/15/2018] [Accepted: 03/15/2018] [Indexed: 11/18/2022] Open
Abstract
Biomembranes with as few as three lipid components can form coexisting liquid-disordered (Ld) and liquid-ordered (Lo) phases. In the coexistence region of Ld and Lo phases, the lipid mixtures 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)/1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/chol or brain sphingomyelin (bSM)/DOPC/chol form micron-scale domains that are easily visualized with light microscopy. Although large domains are not observed in the mixtures DSPC/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/chol and bSM/POPC/chol, lateral heterogeneity is nevertheless detected using techniques with nanometer-scale spatial resolution. We propose a simple and accessible method to measure domain sizes below optical resolution (∼200 nm). We measured nanodomain size for the latter two mixtures by combining experimental Förster resonance energy transfer data with a Monte-Carlo-based analysis. We found a domain radius of 7.5-10 nm for DSPC/POPC/chol, similar to values obtained previously by neutron scattering, and ∼5 nm for bSM/POPC/chol, slightly smaller than measurable by neutron scattering. These analyses also detect the domain-size transition that is observed by fluorescence microscopy in the four-component lipid mixture bSM/DOPC/POPC/chol. Accurate measurements of fluorescent-probe partition coefficients are especially important for the analysis; therefore, we exploit three different methods to measure the partition coefficient of fluorescent molecules between Ld and Lo phases.
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Affiliation(s)
- Thais A Enoki
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York
| | - Frederick A Heberle
- Joint Institute for Biological Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Large Scale Structures Group, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Gerald W Feigenson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York.
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20
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Wiese M, Bannister AJ, Basu S, Boucher W, Wohlfahrt K, Christophorou MA, Nielsen ML, Klenerman D, Laue ED, Kouzarides T. Citrullination of HP1γ chromodomain affects association with chromatin. Epigenetics Chromatin 2019; 12:21. [PMID: 30940194 PMCID: PMC6444592 DOI: 10.1186/s13072-019-0265-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 03/19/2019] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Stem cell differentiation involves major chromatin reorganisation, heterochromatin formation and genomic relocalisation of structural proteins, including heterochromatin protein 1 gamma (HP1γ). As the principal reader of the repressive histone marks H3K9me2/3, HP1 plays a key role in numerous processes including heterochromatin formation and maintenance. RESULTS We find that HP1γ is citrullinated in mouse embryonic stem cells (mESCs) and this diminishes when cells differentiate, indicating that it is a dynamically regulated post-translational modification during stem cell differentiation. Peptidylarginine deiminase 4, a known regulator of pluripotency, citrullinates HP1γ in vitro. This requires R38 and R39 within the HP1γ chromodomain, and the catalytic activity is enhanced by trimethylated H3K9 (H3K9me3) peptides. Mutation of R38 and R39, designed to mimic citrullination, affects HP1γ binding to H3K9me3-containing peptides. Using live-cell single-particle tracking, we demonstrate that R38 and R39 are important for HP1γ binding to chromatin in vivo. Furthermore, their mutation reduces the residence time of HP1γ on chromatin in differentiating mESCs. CONCLUSION Citrullination is a novel post-translational modification of the structural heterochromatin protein HP1γ in mESCs that is dynamically regulated during mESC differentiation. The citrullinated residues lie within the HP1γ chromodomain and are important for H3K9me3 binding in vitro and chromatin association in vivo.
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Affiliation(s)
- Meike Wiese
- The Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN UK
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP UK
- Max Planck Institute for Immunobiology and Epigenetics, Stuebeweg 51, 79108 Freiburg, Germany
| | - Andrew J. Bannister
- The Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN UK
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP UK
| | - Srinjan Basu
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA UK
- Wellcome-MRC Cambridge Stem Cell Institute, Cambridge, CB2 1QR UK
| | - Wayne Boucher
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA UK
| | - Kai Wohlfahrt
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA UK
| | - Maria A. Christophorou
- Institute of Genetics and Molecular Medicine, Western General Hospital, University of Edinburgh, Crewe Road South, Edinburgh, EH4 2XU UK
| | - Michael L. Nielsen
- Department of Proteomics, The Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3b, 2200 Copenhagen, Denmark
| | - David Klenerman
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW UK
| | - Ernest D. Laue
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA UK
| | - Tony Kouzarides
- The Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN UK
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP UK
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21
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Sezgin E, Schneider F, Galiani S, Urbančič I, Waithe D, Lagerholm BC, Eggeling C. Measuring nanoscale diffusion dynamics in cellular membranes with super-resolution STED-FCS. Nat Protoc 2019; 14:1054-1083. [PMID: 30842616 DOI: 10.1038/s41596-019-0127-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 01/04/2019] [Indexed: 11/08/2022]
Abstract
Super-resolution microscopy techniques enable optical imaging in live cells with unprecedented spatial resolution. They unfortunately lack the temporal resolution required to directly investigate cellular dynamics at scales sufficient to measure molecular diffusion. These fast time scales are, on the other hand, routinely accessible by spectroscopic techniques such as fluorescence correlation spectroscopy (FCS). To enable the direct investigation of fast dynamics at the relevant spatial scales, FCS has been combined with super-resolution stimulated emission depletion (STED) microscopy. STED-FCS has been applied in point or scanning mode to reveal nanoscale diffusion behavior of molecules in live cells. In this protocol, we describe the technical details of performing point STED-FCS (pSTED-FCS) and scanning STED-FCS (sSTED-FCS) measurements, from calibration and sample preparation to data acquisition and analysis. We give particular emphasis to 2D diffusion dynamics in cellular membranes, using molecules tagged with organic fluorophores. These measurements can be accomplished within 4-6 h by those proficient in fluorescence imaging.
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Affiliation(s)
- Erdinc Sezgin
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.
| | - Falk Schneider
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Silvia Galiani
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Iztok Urbančič
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
- Solid State Physics Department, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Dominic Waithe
- Wolfson Imaging Centre, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
- MRC Centre for Computational Biology, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - B Christoffer Lagerholm
- Wolfson Imaging Centre, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Christian Eggeling
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.
- Wolfson Imaging Centre, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.
- Institute of Applied Optics, Friedrich-Schiller-University Jena, Jena, Germany.
- Department of Biophysical Imaging, Leibniz Institute of Photonic Technology e.V., Jena, Germany.
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22
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Adler J, Sintorn IM, Strand R, Parmryd I. Conventional analysis of movement on non-flat surfaces like the plasma membrane makes Brownian motion appear anomalous. Commun Biol 2019; 2:12. [PMID: 30652124 PMCID: PMC6325064 DOI: 10.1038/s42003-018-0240-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 11/26/2018] [Indexed: 01/09/2023] Open
Abstract
Cells are neither flat nor smooth, which has serious implications for prevailing plasma membrane models and cellular processes like cell signalling, adhesion and molecular clustering. Using probability distributions from diffusion simulations, we demonstrate that 2D and 3D Euclidean distance measurements substantially underestimate diffusion on non-flat surfaces. Intuitively, the shortest within surface distance (SWSD), the geodesic distance, should reduce this problem. The SWSD is accurate for foldable surfaces but, although it outperforms 2D and 3D Euclidean measurements, it still underestimates movement on deformed surfaces. We demonstrate that the reason behind the underestimation is that topographical features themselves can produce both super- and subdiffusion, i.e. the appearance of anomalous diffusion. Differentiating between topography-induced and genuine anomalous diffusion requires characterising the surface by simulating Brownian motion on high-resolution cell surface images and a comparison with the experimental data.
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Affiliation(s)
- Jeremy Adler
- Science for Life Laboratory, Medical Cell Biology, Uppsala University, Uppsala University, Box 571, 751 21 Uppsala, Sweden
| | - Ida-Maria Sintorn
- Department of Information Technology, Uppsala University, Box 331, 751 05 Uppsala, Sweden
| | - Robin Strand
- Department of Information Technology, Uppsala University, Box 331, 751 05 Uppsala, Sweden
| | - Ingela Parmryd
- Science for Life Laboratory, Medical Cell Biology, Uppsala University, Uppsala University, Box 571, 751 21 Uppsala, Sweden
- Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden
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23
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Slator PJ, Burroughs NJ. A Hidden Markov Model for Detecting Confinement in Single-Particle Tracking Trajectories. Biophys J 2018; 115:1741-1754. [PMID: 30274829 PMCID: PMC6226389 DOI: 10.1016/j.bpj.2018.09.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 07/20/2018] [Accepted: 09/04/2018] [Indexed: 01/08/2023] Open
Abstract
State-of-the-art single-particle tracking (SPT) techniques can generate long trajectories with high temporal and spatial resolution. This offers the possibility of mechanistically interpreting particle movements and behavior in membranes. To this end, a number of statistical techniques have been developed that partition SPT trajectories into states with distinct diffusion signatures, allowing a statistical analysis of diffusion state dynamics and switching behavior. Here, we develop a confinement model, within a hidden Markov framework, that switches between phases of free diffusion and confinement in a harmonic potential well. By using a Markov chain Monte Carlo algorithm to fit this model, automated partitioning of individual SPT trajectories into these two phases is achieved, which allows us to analyze confinement events. We demonstrate the utility of this algorithm on a previously published interferometric scattering microscopy data set, in which gold-nanoparticle-tagged ganglioside GM1 lipids were tracked in model membranes. We performed a comprehensive analysis of confinement events, demonstrating that there is heterogeneity in the lifetime, shape, and size of events, with confinement size and shape being highly conserved within trajectories. Our observations suggest that heterogeneity in confinement events is caused by both individual nanoparticle characteristics and the binding-site environment. The individual nanoparticle heterogeneity ultimately limits the ability of interferometric scattering microscopy to resolve molecule dynamics to the order of the tag size; homogeneous tags could potentially allow the resolution to be taken below this limit by deconvolution methods. In a wider context, the presented harmonic potential well confinement model has the potential to detect and characterize a wide variety of biological phenomena, such as hop diffusion, receptor clustering, and lipid rafts.
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Affiliation(s)
- Paddy J Slator
- Centre for Medical Image Computing and Department of Computer Science, University College London, London, United Kingdom; Systems Biology Doctoral Training Centre, University of Warwick, Coventry, United Kingdom
| | - Nigel J Burroughs
- Mathematics Institute, University of Warwick, Coventry, United Kingdom.
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24
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Schneider F, Waithe D, Lagerholm BC, Shrestha D, Sezgin E, Eggeling C, Fritzsche M. Statistical Analysis of Scanning Fluorescence Correlation Spectroscopy Data Differentiates Free from Hindered Diffusion. ACS Nano 2018; 12:8540-8546. [PMID: 30028588 PMCID: PMC6117752 DOI: 10.1021/acsnano.8b04080] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 07/20/2018] [Indexed: 05/28/2023]
Abstract
Cells rely on versatile diffusion dynamics in their plasma membrane. Quantification of this often heterogeneous diffusion is essential to the understanding of cell regulation and function. Yet such measurements remain a major challenge in cell biology, usually due to low sampling throughput, a necessity for dedicated equipment, sophisticated fluorescent label strategies, and limited sensitivity. Here, we introduce a robust, broadly applicable statistical analysis pipeline for large scanning fluorescence correlation spectroscopy data sets, which uncovers the nanoscale heterogeneity of the plasma membrane in living cells by differentiating free from hindered diffusion modes of fluorescent lipid and protein analogues.
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Affiliation(s)
- Falk Schneider
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
| | - Dominic Waithe
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
| | - B. Christoffer Lagerholm
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
| | - Dilip Shrestha
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
| | - Erdinc Sezgin
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
| | - Christian Eggeling
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
- Institute of Applied
Optics, Friedrich-Schiller-University and
Leibniz Institute of Photonic Technology, Helmholtzweg 4, 07743 Jena, Germany
| | - Marco Fritzsche
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
- Kennedy
Institute for Rheumatology, University of
Oxford, Roosevelt Drive, Oxford OX3 7LF, United Kingdom
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25
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Basu S, Needham LM, Lando D, Taylor EJR, Wohlfahrt KJ, Shah D, Boucher W, Tan YL, Bates LE, Tkachenko O, Cramard J, Lagerholm BC, Eggeling C, Hendrich B, Klenerman D, Lee SF, Laue ED. FRET-enhanced photostability allows improved single-molecule tracking of proteins and protein complexes in live mammalian cells. Nat Commun 2018; 9:2520. [PMID: 29955052 PMCID: PMC6023872 DOI: 10.1038/s41467-018-04486-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 04/27/2018] [Indexed: 11/09/2022] Open
Abstract
A major challenge in single-molecule imaging is tracking the dynamics of proteins or complexes for long periods of time in the dense environments found in living cells. Here, we introduce the concept of using FRET to enhance the photophysical properties of photo-modulatable (PM) fluorophores commonly used in such studies. By developing novel single-molecule FRET pairs, consisting of a PM donor fluorophore (either mEos3.2 or PA-JF549) next to a photostable acceptor dye JF646, we demonstrate that FRET competes with normal photobleaching kinetic pathways to increase the photostability of both donor fluorophores. This effect was further enhanced using a triplet-state quencher. Our approach allows us to significantly improve single-molecule tracking of chromatin-binding proteins in live mammalian cells. In addition, it provides a novel way to track the localization and dynamics of protein complexes by labeling one protein with the PM donor and its interaction partner with the acceptor dye.
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Affiliation(s)
- Srinjan Basu
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Lisa-Maria Needham
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - David Lando
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Edward J R Taylor
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Kai J Wohlfahrt
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Devina Shah
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Wayne Boucher
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Yi Lei Tan
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Lawrence E Bates
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Olga Tkachenko
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Julie Cramard
- Wellcome Trust - MRC Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QR, UK
| | - B Christoffer Lagerholm
- Medical Research Council Human Immunology Unit and Wolfson Imaging Centre, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford, OX3 9DS, UK
| | - Christian Eggeling
- Medical Research Council Human Immunology Unit and Wolfson Imaging Centre, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford, OX3 9DS, UK
| | - Brian Hendrich
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK.,Wellcome Trust - MRC Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QR, UK
| | - Dave Klenerman
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
| | - Steven F Lee
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
| | - Ernest D Laue
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK.
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26
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Reina F, Galiani S, Shrestha D, Sezgin E, de Wit G, Cole D, Christoffer Lagerholm B, Kukura P, Eggeling C. Complementary studies of lipid membrane dynamics using iSCAT and super-resolved fluorescence correlation spectroscopy. J Phys D Appl Phys 2018; 51:235401. [PMID: 29853718 PMCID: PMC5964363 DOI: 10.1088/1361-6463/aac04f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 04/12/2018] [Accepted: 04/26/2018] [Indexed: 05/20/2023]
Abstract
Observation techniques with high spatial and temporal resolution, such as single-particle tracking based on interferometric scattering (iSCAT) microscopy, and fluorescence correlation spectroscopy applied on a super-resolution STED microscope (STED-FCS), have revealed new insights of the molecular organization of membranes. While delivering complementary information, there are still distinct differences between these techniques, most prominently the use of fluorescent dye tagged probes for STED-FCS and a need for larger scattering gold nanoparticle tags for iSCAT. In this work, we have used lipid analogues tagged with a hybrid fluorescent tag-gold nanoparticle construct, to directly compare the results from STED-FCS and iSCAT measurements of phospholipid diffusion on a homogeneous supported lipid bilayer (SLB). These comparative measurements showed that while the mode of diffusion remained free, at least at the spatial (>40 nm) and temporal (50 ⩽ t ⩽ 100 ms) scales probed, the diffussion coefficient was reduced by 20- to 60-fold when tagging with 20 and 40 nm large gold particles as compared to when using dye tagged lipid analogues. These FCS measurements of hybrid fluorescent tag-gold nanoparticle labeled lipids also revealed that commercially supplied streptavidin-coated gold nanoparticles contain large quantities of free streptavidin. Finally, the values of apparent diffusion coefficients obtained by STED-FCS and iSCAT differed by a factor of 2-3 across the techniques, while relative differences in mobility between different species of lipid analogues considered were identical in both approaches. In conclusion, our experiments reveal that large and potentially cross-linking scattering tags introduce a significant slow-down in diffusion on SLBs but no additional bias, and our labeling approach creates a new way of exploiting complementary information from STED-FCS and iSCAT measurements.
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Affiliation(s)
- Francesco Reina
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Silvia Galiani
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Dilip Shrestha
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Erdinc Sezgin
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Gabrielle de Wit
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Daniel Cole
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - B Christoffer Lagerholm
- Wolfson Imaging Centre Oxford, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Philipp Kukura
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Christian Eggeling
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
- Wolfson Imaging Centre Oxford, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
- Institute of Applied Optics, Friedrich-Schiller University, Jena, Germany
- Leibniz Institute of Photonic Technology (IPHT), Jena, Germany
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27
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Miller H, Cosgrove J, Wollman AJM, Taylor E, Zhou Z, O'Toole PJ, Coles MC, Leake MC. High-Speed Single-Molecule Tracking of CXCL13 in the B-Follicle. Front Immunol 2018; 9:1073. [PMID: 29872430 PMCID: PMC5972203 DOI: 10.3389/fimmu.2018.01073] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/30/2018] [Indexed: 12/12/2022] Open
Abstract
Soluble factors are an essential means of communication between cells and their environment. However, many molecules readily interact with extracellular matrix components, giving rise to multiple modes of diffusion. The molecular quantification of diffusion in situ is thus a challenging imaging frontier, requiring very high spatial and temporal resolution. Overcoming this methodological barrier is key to understanding the precise spatial patterning of the extracellular factors that regulate immune function. To address this, we have developed a high-speed light microscopy system capable of millisecond sampling in ex vivo tissue samples and submillisecond sampling in controlled in vitro samples to characterize molecular diffusion in a range of complex microenvironments. We demonstrate that this method outperforms competing tools for determining molecular mobility of fluorescence correlation spectroscopy (FCS) and fluorescence recovery after photobleaching (FRAP) for evaluation of diffusion. We then apply this approach to study the chemokine CXCL13, a key determinant of lymphoid tissue architecture, and B-cell-mediated immunity. Super-resolution single-molecule tracking of fluorescently labeled CCL19 and CXCL13 in collagen matrix was used to assess the heterogeneity of chemokine mobility behaviors, with results indicating an immobile fraction and a mobile fraction for both molecules, with distinct diffusion rates of 8.4 ± 0.2 and 6.2 ± 0.3 µm2s−1, respectively. To better understand mobility behaviors in situ, we analyzed CXCL13-AF647 diffusion in murine lymph node tissue sections and observed both an immobile fraction and a mobile fraction with an example diffusion coefficient of 6.6 ± 0.4 µm2s−1, suggesting that mobility within the follicle is also multimodal. In quantitatively studying mobility behaviors at the molecular level, we have obtained an increased understanding of CXCL13 bioavailability within the follicle. Our high-speed single-molecule tracking approach affords a novel perspective from which to understand the mobility of soluble factors relevant to the immune system.
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Affiliation(s)
- Helen Miller
- Department of Physics, University of York, York, United Kingdom.,Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Jason Cosgrove
- Centre of Immunology and Infection, University of York, York, United Kingdom.,Department of Biology, University of York, York, United Kingdom.,Department of Electronics, University of York, York, United Kingdom
| | - Adam J M Wollman
- Department of Physics, University of York, York, United Kingdom.,Department of Biology, University of York, York, United Kingdom
| | - Emily Taylor
- Centre of Immunology and Infection, University of York, York, United Kingdom.,Department of Biology, University of York, York, United Kingdom
| | - Zhaokun Zhou
- Department of Physics, University of York, York, United Kingdom.,Department of Biology, University of York, York, United Kingdom
| | - Peter J O'Toole
- Department of Biology, University of York, York, United Kingdom.,Bioscience Technology Facility, University of York, York, United Kingdom
| | - Mark C Coles
- Centre of Immunology and Infection, University of York, York, United Kingdom.,Department of Biology, University of York, York, United Kingdom.,Kennedy Institute of Rheumatology, University of Oxford, Oxford, United Kingdom
| | - Mark C Leake
- Department of Physics, University of York, York, United Kingdom.,Department of Biology, University of York, York, United Kingdom
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28
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Raghunathan K, Kenworthy AK. Dynamic pattern generation in cell membranes: Current insights into membrane organization. Biochim Biophys Acta Biomembr 2018; 1860:2018-2031. [PMID: 29752898 DOI: 10.1016/j.bbamem.2018.05.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/30/2018] [Accepted: 05/03/2018] [Indexed: 12/18/2022]
Abstract
It has been two decades since the lipid raft hypothesis was first presented. Even today, whether these nanoscale cholesterol-rich domains are present in cell membranes is not completely resolved. However, especially in the last few years, a rich body of literature has demonstrated both the presence and the importance of non-random distribution of biomolecules on the membrane, which is the focus of this review. These new developments have pushed the experimental limits of detection and have brought us closer to observing lipid domains in the plasma membrane of live cells. Characterization of biomolecules associated with lipid rafts has revealed a deep connection between biological regulation and function and membrane compositional heterogeneities. Finally, tantalizing new developments in the field have demonstrated that lipid domains might not just be associated with the plasma membrane of eukaryotes but could potentially be a ubiquitous membrane-organizing principle in several other biological systems. This article is part of a Special Issue entitled: Emergence of Complex Behavior in Biomembranes edited by Marjorie Longo.
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Affiliation(s)
- Krishnan Raghunathan
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, PA 15224, USA.
| | - Anne K Kenworthy
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA.
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29
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Shin W, Ge L, Arpino G, Villarreal SA, Hamid E, Liu H, Zhao WD, Wen PJ, Chiang HC, Wu LG. Visualization of Membrane Pore in Live Cells Reveals a Dynamic-Pore Theory Governing Fusion and Endocytosis. Cell 2018; 173:934-945.e12. [PMID: 29606354 DOI: 10.1016/j.cell.2018.02.062] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 02/22/2018] [Accepted: 02/27/2018] [Indexed: 01/03/2023]
Abstract
Fusion is thought to open a pore to release vesicular cargoes vital for many biological processes, including exocytosis, intracellular trafficking, fertilization, and viral entry. However, fusion pores have not been observed and thus proved in live cells. Its regulatory mechanisms and functions remain poorly understood. With super-resolution STED microscopy, we observed dynamic fusion pore behaviors in live (neuroendocrine) cells, including opening, expansion, constriction, and closure, where pore size may vary between 0 and 490 nm within 26 milliseconds to seconds (vesicle size: 180-720 nm). These pore dynamics crucially determine the efficiency of vesicular cargo release and vesicle retrieval. They are generated by competition between pore expansion and constriction. Pharmacology and mutation experiments suggest that expansion and constriction are mediated by F-actin-dependent membrane tension and calcium/dynamin, respectively. These findings provide the missing live-cell evidence, proving the fusion-pore hypothesis, and establish a live-cell dynamic-pore theory accounting for fusion, fission, and their regulation.
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Affiliation(s)
- Wonchul Shin
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Lihao Ge
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Gianvito Arpino
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Seth A Villarreal
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Edaeni Hamid
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Huisheng Liu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Wei-Dong Zhao
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Peter J Wen
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Hsueh-Cheng Chiang
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
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30
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Batta G, Soltész L, Kovács T, Bozó T, Mészár Z, Kellermayer M, Szöllősi J, Nagy P. Alterations in the properties of the cell membrane due to glycosphingolipid accumulation in a model of Gaucher disease. Sci Rep 2018; 8:157. [PMID: 29317695 DOI: 10.1038/s41598-017-18405-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/11/2017] [Indexed: 01/07/2023] Open
Abstract
Gaucher disease is a lysosomal storage disease characterized by the malfunction of glucocerebrosidase resulting in the accumulation of glucosylceramide and other sphingolipids in certain cells. Although the disease symptoms are usually attributed to the storage of undigested substrate in lysosomes, here we show that glycosphingolipids accumulating in the plasma membrane cause profound changes in the properties of the membrane. The fluidity of the sphingolipid-enriched membrane decreased accompanied by the enlargement of raft-like ordered membrane domains. The mobility of non-raft proteins and lipids was severely restricted, while raft-resident components were only mildly affected. The rate of endocytosis of transferrin receptor, a non-raft protein, was significantly retarded in Gaucher cells, while the endocytosis of the raft-associated GM1 ganglioside was unaffected. Interferon-γ-induced STAT1 phosphorylation was also significantly inhibited in Gaucher cells. Atomic force microscopy revealed that sphingolipid accumulation was associated with a more compliant membrane capable of producing an increased number of nanotubes. The results imply that glycosphingolipid accumulation in the plasma membrane has significant effects on membrane properties, which may be important in the pathogenesis of Gaucher disease.
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31
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Kabbani AM, Kelly CV. Nanoscale Membrane Budding Induced by CTxB and Detected via Polarized Localization Microscopy. Biophys J 2017; 113:1795-1806. [PMID: 29045873 DOI: 10.1016/j.bpj.2017.08.031] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 08/07/2017] [Accepted: 08/11/2017] [Indexed: 11/17/2022] Open
Abstract
For endocytosis and exocytosis, membranes transition among planar, budding, and vesicular topographies through nanoscale reorganization of lipids, proteins, and carbohydrates. However, prior attempts to understand the initial stages of nanoscale bending have been limited by experimental resolution. Through the implementation of polarized localization microscopy, this article reports the inherent membrane bending capability of cholera toxin subunit B (CTxB) in quasi-one-component-supported lipid bilayers. Membrane buds were first detected with <50 nm radius, grew to >200 nm radius, and extended into longer tubules with dependence on the membrane tension and CTxB concentration. Compared to the concentration of the planar-supported lipid bilayers, CTxB was (12 ± 4)× more concentrated on the positive curvature top and (26 ± 11)× more concentrated on the negative Gaussian curvature neck of the nanoscale membrane buds. CTxB is frequently used as a marker for liquid-ordered lipid phases; however, the coupling between CTxB and membrane bending provides an alternate understanding of CTxB-induced membrane reorganization. These findings allow for the reinterpretation of prior observations by correlating CTxB clustering and diffusion to CTxB-induced membrane bending. Single-particle tracking was performed on single lipids and CTxB to reveal the correlations among single-molecule diffusion, CTxB accumulation, and membrane topography. Slowed lipid and CTxB diffusion was observed at the nanoscale bud locations, suggesting a local increase in the effective membrane viscosity or molecular crowding upon membrane bending. These results suggest inherent CTxB-induced membrane bending as a mechanism for initiating CTxB internalization in cells that could be independent of clathrin, caveolin, actin, and lipid phase separation.
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Affiliation(s)
- Abir M Kabbani
- Department of Physics and Astronomy, Wayne State University, Detroit, Michigan
| | - Christopher V Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, Michigan.
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32
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Kabbani AM, Kelly CV. The Detection of Nanoscale Membrane Bending with Polarized Localization Microscopy. Biophys J 2017; 113:1782-1794. [PMID: 29045872 PMCID: PMC5647545 DOI: 10.1016/j.bpj.2017.07.034] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/20/2017] [Accepted: 07/25/2017] [Indexed: 11/22/2022] Open
Abstract
The curvature of biological membranes at the nanometer scale is critically important for vesicle trafficking, organelle morphology, and disease propagation. The initiation of membrane bending occurs at a length scale that is irresolvable by most superresolution optical microscopy methods. Here, we report the development of polarized localization microscopy (PLM), a pointillist optical imaging technique for the detection of nanoscale membrane curvature in correlation with single-molecule dynamics and molecular sorting. PLM combines polarized total internal reflection fluorescence microscopy and single-molecule localization microscopy to reveal membrane orientation with subdiffraction-limited resolution without reducing localization precision by point spread function manipulation. Membrane curvature detection with PLM requires fewer localization events to detect curvature than three-dimensional single-molecule localization microscopy (e.g., photoactivated localization microscopy or stochastic optical reconstruction microscopy), which enables curvature detection 10× faster via PLM. With rotationally confined lipophilic fluorophores and the polarized incident fluorescence excitation, membrane-bending events are revealed with superresolution. Engineered hemispherical membrane curvature with a radius ≥24 nm was detected with PLM, and individual fluorophore localization precision was 13 ± 5 nm. Further, deciphering molecular mobility as a function of membrane topology was enabled. The diffusion coefficient of individual DiI molecules was 25 ± 5× higher in planar supported lipid bilayers than within nanoscale membrane curvature. Through the theoretical foundation and experimental demonstration provided here, PLM is poised to become a powerful technique for revealing the underlying biophysical mechanisms of membrane bending at physiological length scales.
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Affiliation(s)
- Abir M Kabbani
- Department of Physics and Astronomy, Wayne State University, Detroit, Michigan
| | - Christopher V Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, Michigan.
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33
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Affiliation(s)
- Wei Liu
- Department of Physics; The Chinese University of Hong Kong; Shatin N.T. Hong Kong 999077
| | - Chi Wu
- Department of Chemistry; The Chinese University of Hong Kong; Shatin N.T. Hong Kong 999077
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