1
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Lebreton S, Paladino S, Lelek M, Tramier M, Zimmer C, Zurzolo C. Actin cytoskeleton differently regulates cell surface organization of GPI-anchored proteins in polarized epithelial cells and fibroblasts. Front Mol Biosci 2024; 11:1360142. [PMID: 38774234 PMCID: PMC11106487 DOI: 10.3389/fmolb.2024.1360142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 04/11/2024] [Indexed: 05/24/2024] Open
Abstract
The spatiotemporal compartmentalization of membrane-associated glycosylphosphatidylinositol-anchored proteins (GPI-APs) on the cell surface regulates their biological activities. These GPI-APs occupy distinct cellular functions such as enzymes, receptors, and adhesion molecules, and they are implicated in several vital cellular processes. Thus, unraveling the mechanisms and regulators of their membrane organization is essential. In polarized epithelial cells, GPI-APs are enriched at the apical surface, where they form small cholesterol-independent homoclusters and larger heteroclusters accommodating multiple GPI-AP species, all confined within areas of approximately 65-70 nm in diameter. Notably, GPI-AP homoclustering occurs in the Golgi apparatus through a cholesterol- and calcium-dependent mechanism that drives their apical sorting. Despite the critical role of Golgi GPI-AP clustering in their cell surface organization and the importance of cholesterol in heterocluster formation, the regulatory mechanisms governing GPI-AP surface organization, particularly in the context of epithelial polarity, remain elusive. Given that the actin cytoskeleton undergoes substantial remodeling during polarity establishment, this study explores whether the actin cytoskeleton regulates the spatiotemporal apical organization of GPI-APs in MDCK cells. Utilizing various imaging techniques (number and brightness, FRET/FLIM, and dSTORM coupled to pair correlation analysis), we demonstrate that the apical organization of GPI-APs, at different scales, does not rely on the actin cytoskeleton, unlike in fibroblastic cells. Interestingly, calcium chelation disrupts the organization of GPI-APs at the apical surface by impairing Golgi GPI-AP clustering, emphasizing the existence of an interplay among Golgi clustering, apical sorting, and surface organization in epithelial cells. In summary, our findings unveil distinct mechanisms regulating the organization of GPI-APs in cell types of different origins, plausibly allowing them to adapt to different external signals and different cellular environments in order to achieve specialized functions.
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Affiliation(s)
- Stéphanie Lebreton
- Institut Pasteur, Unité de Trafic Membranaire et Pathogenèse, Paris, France
| | - Simona Paladino
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy
| | - Mickaël Lelek
- Imaging and Modeling Unit, Department of Computational Biology, Institut Pasteur, Paris, France
| | - Marc Tramier
- Université Rennes, Centre National de la recherche scientifique, IGDR (Genetics and Development Institute of Rennes), Unité mixte de receherche 6290, Rennes, France
| | - Christophe Zimmer
- Imaging and Modeling Unit, Department of Computational Biology, Institut Pasteur, Paris, France
- Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | - Chiara Zurzolo
- Institut Pasteur, Unité de Trafic Membranaire et Pathogenèse, Paris, France
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy
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2
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Trujillo J, Khan AS, Adhikari DP, Stoneman MR, Chacko JV, Eliceiri KW, Raicu V. Implementation of FRET Spectrometry Using Temporally Resolved Fluorescence: A Feasibility Study. Int J Mol Sci 2024; 25:4706. [PMID: 38731924 PMCID: PMC11083457 DOI: 10.3390/ijms25094706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2024] [Revised: 04/21/2024] [Accepted: 04/22/2024] [Indexed: 05/13/2024] Open
Abstract
Förster resonance energy transfer (FRET) spectrometry is a method for determining the quaternary structure of protein oligomers from distributions of FRET efficiencies that are drawn from pixels of fluorescence images of cells expressing the proteins of interest. FRET spectrometry protocols currently rely on obtaining spectrally resolved fluorescence data from intensity-based experiments. Another imaging method, fluorescence lifetime imaging microscopy (FLIM), is a widely used alternative to compute FRET efficiencies for each pixel in an image from the reduction of the fluorescence lifetime of the donors caused by FRET. In FLIM studies of oligomers with different proportions of donors and acceptors, the donor lifetimes may be obtained by fitting the temporally resolved fluorescence decay data with a predetermined number of exponential decay curves. However, this requires knowledge of the number and the relative arrangement of the fluorescent proteins in the sample, which is precisely the goal of FRET spectrometry, thus creating a conundrum that has prevented users of FLIM instruments from performing FRET spectrometry. Here, we describe an attempt to implement FRET spectrometry on temporally resolved fluorescence microscopes by using an integration-based method of computing the FRET efficiency from fluorescence decay curves. This method, which we dubbed time-integrated FRET (or tiFRET), was tested on oligomeric fluorescent protein constructs expressed in the cytoplasm of living cells. The present results show that tiFRET is a promising way of implementing FRET spectrometry and suggest potential instrument adjustments for increasing accuracy and resolution in this kind of study.
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Affiliation(s)
- Justin Trujillo
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA; (J.T.); (A.S.K.); (D.P.A.); (M.R.S.)
| | - Aliyah S. Khan
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA; (J.T.); (A.S.K.); (D.P.A.); (M.R.S.)
| | - Dhruba P. Adhikari
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA; (J.T.); (A.S.K.); (D.P.A.); (M.R.S.)
| | - Michael R. Stoneman
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA; (J.T.); (A.S.K.); (D.P.A.); (M.R.S.)
| | - Jenu V. Chacko
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53705, USA; (J.V.C.); (K.W.E.)
| | - Kevin W. Eliceiri
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53705, USA; (J.V.C.); (K.W.E.)
- Departments of Biomedical Engineering and Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA
- Morgridge Institute for Research, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Valerica Raicu
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA; (J.T.); (A.S.K.); (D.P.A.); (M.R.S.)
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3
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Starling T, Carlon-Andres I, Iliopoulou M, Kraemer B, Loidolt-Krueger M, Williamson DJ, Padilla-Parra S. Multicolor lifetime imaging and its application to HIV-1 uptake. Nat Commun 2023; 14:4994. [PMID: 37591879 PMCID: PMC10435470 DOI: 10.1038/s41467-023-40731-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 08/04/2023] [Indexed: 08/19/2023] Open
Abstract
Simultaneous imaging of nine fluorescent proteins is demonstrated in a single acquisition using fluorescence lifetime imaging microscopy combined with pulsed interleaved excitation of three laser lines. Multicolor imaging employing genetically encodable fluorescent proteins permits spatio-temporal live cell imaging of multiple cues. Here, we show that multicolor lifetime imaging allows visualization of quadruple labelled human immunodeficiency viruses on host cells that in turn are also labelled with genetically encodable fluorescent proteins. This strategy permits to simultaneously visualize different sub-cellular organelles (mitochondria, cytoskeleton, and nucleus) during the process of virus entry with the potential of imaging up to nine different spectral channels in living cells.
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Affiliation(s)
- Tobias Starling
- Department of Infectious Diseases, King's College London, Faculty of Life Sciences & Medicine, London, UK
| | - Irene Carlon-Andres
- Department of Infectious Diseases, King's College London, Faculty of Life Sciences & Medicine, London, UK
| | - Maro Iliopoulou
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
- Randall Division of Cell and Molecular Biophysics and Department of Physics, King's College London, London, UK
| | - Benedikt Kraemer
- PicoQuant GmbH, Rudower Chaussee 29 (IGZ), 12489, Berlin, Germany
| | | | - David J Williamson
- Department of Infectious Diseases, King's College London, Faculty of Life Sciences & Medicine, London, UK
| | - Sergi Padilla-Parra
- Department of Infectious Diseases, King's College London, Faculty of Life Sciences & Medicine, London, UK.
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK.
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4
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Auer JMT, Murphy LC, Xiao D, Li DU, Wheeler AP. Non-fitting FLIM-FRET facilitates analysis of protein interactions in live zebrafish embryos. J Microsc 2022. [PMID: 36448983 DOI: 10.1111/jmi.13162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 12/05/2022]
Abstract
Molecular interactions are key to all cellular processes, and particularly interesting to investigate in the context of gene regulation. Protein-protein interactions are challenging to examine in vivo as they are dynamic, and require spatially and temporally resolved studies to interrogate them. Foerster Resonance Energy Transfer (FRET) is a highly sensitive imaging method, which can interrogate molecular interactions. FRET can be detected by Fluorescence Lifetime Imaging Microscopy (FLIM-FRET), which is more robust to concentration variations and photobleaching than intensity-based FRET but typically needs long acquisition times to achieve high photon counts. New variants of non-fitting lifetime-based FRET perform well in samples with lower signal and require less intensive instrument calibration and analysis, making these methods ideal for probing protein-protein interactions in more complex live 3D samples. Here we show that a non-fitting FLIM-FRET variant, based on the Average Arrival Time of photons per pixel (AAT- FRET), is a sensitive and simple way to detect and measure protein-protein interactions in live early stage zebrafish embryos.
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Affiliation(s)
- Julia M T Auer
- MRC Human Genetics Unit, Institute of Genetics and Cancer, The University of Edinburgh, Edinburgh, UK
| | - Laura C Murphy
- MRC Human Genetics Unit, Institute of Genetics and Cancer, The University of Edinburgh, Edinburgh, UK
| | - Dong Xiao
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK
| | - David U Li
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK
| | - Ann P Wheeler
- MRC Human Genetics Unit, Institute of Genetics and Cancer, The University of Edinburgh, Edinburgh, UK
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5
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Li J, Liu Y, Li Y, Zhang Z, Qu S. Bovine serum albumin label-free concentration sensor based on silica corrosion quantitative monitoring system. OPTICS EXPRESS 2022; 30:21725-21735. [PMID: 36224885 DOI: 10.1364/oe.459673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/19/2022] [Indexed: 06/16/2023]
Abstract
Bovine serum albumin (BSA) label-free concentration sensor based on silica corrosion quantitative monitoring system (SCQMS) has been proposed. Anti-resonance of hollow cylindrical waveguide (HCW) in SCQMS is simulated and investigated for monitoring corrosion rate quantitatively. Hydrofluoric acid (HF) samples with different concentrations are studied respectively, and the corrosion rate is obtained by demodulating the corresponding anti-resonance dips shift and free spectral range (FSR). Therefore, a high-precision SQCMS was prepared successfully. On this basis, a highly sensitive concentration sensor based on hole-assisted dual-core fiber (HADF) is prepared. The BSA samples with concentration from 0.2 mg/mL to 0.7 mg/mL are detected. The sensor has a high sensitivity of 30.04 nm/(mg/mL) and ultra-low limit of detection (LOD) of 0.05 mg/mL for the assisted core exposed to the target solution directly. We have demonstrated the SCQMS that can be a feasible tool for precise and quantitative corrosion of silicon structure safely. In addition, the concentration sensor structure has a wide application for ultra-low LOD, simple preparation process and high integration.
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6
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Héliot L, Leray A. Simple phasor-based deep neural network for fluorescence lifetime imaging microscopy. Sci Rep 2021; 11:23858. [PMID: 34903737 PMCID: PMC8668934 DOI: 10.1038/s41598-021-03060-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 11/23/2021] [Indexed: 12/29/2022] Open
Abstract
Fluorescence lifetime imaging microscopy (FLIM) is a powerful technique to probe the molecular environment of fluorophores. The analysis of FLIM images is usually performed with time consuming fitting methods. For accelerating this analysis, sophisticated deep learning architectures based on convolutional neural networks have been developed for restrained lifetime ranges but they require long training time. In this work, we present a simple neural network formed only with fully connected layers able to analyze fluorescence lifetime images. It is based on the reduction of high dimensional fluorescence intensity temporal decays into four parameters which are the phasor coordinates, the mean and amplitude-weighted lifetimes. This network called Phasor-Net has been applied for a time domain FLIM system excited with an 80 MHz laser repetition frequency, with negligible jitter and afterpulsing. Due to the restricted time interval of 12.5 ns, the training range of the lifetimes was limited between 0.2 and 3.0 ns; and the total photon number was lower than 106, as encountered in live cell imaging. From simulated biexponential decays, we demonstrate that Phasor-Net is more precise and less biased than standard fitting methods. We demonstrate also that this simple architecture gives almost comparable performance than those obtained from more sophisticated networks but with a faster training process (15 min instead of 30 min). We finally apply successfully our method to determine biexponential decays parameters for FLIM experiments in living cells expressing EGFP linked to mCherry and fused to a plasma membrane protein.
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Affiliation(s)
- Laurent Héliot
- PhLAM Laboratoire de Physique Des Lasers, Atomes Et Molécules, UMR 8523, CNRS, University of Lille, Lille, France.
| | - Aymeric Leray
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303, CNRS, Université de Bourgogne Franche-Comté, Dijon, France.
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7
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Eckenstaler R, Benndorf RA. A Combined Acceptor Photobleaching and Donor Fluorescence Lifetime Imaging Microscopy Approach to Analyze Multi-Protein Interactions in Living Cells. Front Mol Biosci 2021; 8:635548. [PMID: 34055873 PMCID: PMC8160235 DOI: 10.3389/fmolb.2021.635548] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 04/19/2021] [Indexed: 11/13/2022] Open
Abstract
Protein-protein interaction studies often provide new insights, i.e., into the formation of protein complexes relevant for structural oligomerization, regulation of enzymatic activity or information transfer within signal transduction pathways. Mostly, biochemical approaches have been used to study such interactions, but their results are limited to observations from lysed cells. A powerful tool for the non-invasive investigation of protein-protein interactions in the context of living cells is the microscopic analysis of Förster Resonance Energy Transfer (FRET) among fluorescent proteins. Normally, FRET is used to monitor the interaction state of two proteins, but in addition, FRET studies have been used to investigate three or more interacting proteins at the same time. Here we describe a fluorescence microscopy-based method which applies a novel 2-step acceptor photobleaching protocol to discriminate between non-interacting, dimeric interacting and trimeric interacting states within a three-fluorophore setup. For this purpose, intensity- and fluorescence lifetime-related FRET effects were analyzed on representative fluorescent dimeric and trimeric FRET-constructs expressed in the cytosol of HEK293 cells. In particular, by combining FLIM- and intensity-based FRET data acquisition and interpretation, our method allows to distinguish trimeric from different types of dimeric (single-, double- or triple-dimeric) protein-protein interactions of three potential interaction partners in the physiological setting of living cells.
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Affiliation(s)
- Robert Eckenstaler
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Ralf A Benndorf
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Halle, Germany
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8
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Rozbesky D, Verhagen MG, Karia D, Nagy GN, Alvarez L, Robinson RA, Harlos K, Padilla‐Parra S, Pasterkamp RJ, Jones EY. Structural basis of semaphorin-plexin cis interaction. EMBO J 2020; 39:e102926. [PMID: 32500924 PMCID: PMC7327498 DOI: 10.15252/embj.2019102926] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 01/05/2023] Open
Abstract
Semaphorin ligands interact with plexin receptors to contribute to functions in the development of myriad tissues including neurite guidance and synaptic organisation within the nervous system. Cell-attached semaphorins interact in trans with plexins on opposing cells, but also in cis on the same cell. The interplay between trans and cis interactions is crucial for the regulated development of complex neural circuitry, but the underlying molecular mechanisms are uncharacterised. We have discovered a distinct mode of interaction through which the Drosophila semaphorin Sema1b and mouse Sema6A mediate binding in cis to their cognate plexin receptors. Our high-resolution structural, biophysical and in vitro analyses demonstrate that monomeric semaphorins can mediate a distinctive plexin binding mode. These findings suggest the interplay between monomeric vs dimeric states has a hereto unappreciated role in semaphorin biology, providing a mechanism by which Sema6s may balance cis and trans functionalities.
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Affiliation(s)
- Daniel Rozbesky
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Marieke G Verhagen
- Department of Translational NeuroscienceUMC Utrecht Brain CenterUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Dimple Karia
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Gergely N Nagy
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Luis Alvarez
- Cellular ImagingWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Ross A Robinson
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
- Present address:
Immunocore LtdAbingdonUK
| | - Karl Harlos
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Sergi Padilla‐Parra
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
- Cellular ImagingWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
- Present address:
Department of Infectious DiseasesFaculty of Life Sciences & MedicineKing's College LondonLondonUK
- Present address:
Randall Centre for Cell and Molecular BiophysicsKing's College LondonLondonUK
| | - R Jeroen Pasterkamp
- Department of Translational NeuroscienceUMC Utrecht Brain CenterUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Edith Yvonne Jones
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
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9
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Datta R, Heaster TM, Sharick JT, Gillette AA, Skala MC. Fluorescence lifetime imaging microscopy: fundamentals and advances in instrumentation, analysis, and applications. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:1-43. [PMID: 32406215 PMCID: PMC7219965 DOI: 10.1117/1.jbo.25.7.071203] [Citation(s) in RCA: 318] [Impact Index Per Article: 79.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 04/24/2020] [Indexed: 05/18/2023]
Abstract
SIGNIFICANCE Fluorescence lifetime imaging microscopy (FLIM) is a powerful technique to distinguish the unique molecular environment of fluorophores. FLIM measures the time a fluorophore remains in an excited state before emitting a photon, and detects molecular variations of fluorophores that are not apparent with spectral techniques alone. FLIM is sensitive to multiple biomedical processes including disease progression and drug efficacy. AIM We provide an overview of FLIM principles, instrumentation, and analysis while highlighting the latest developments and biological applications. APPROACH This review covers FLIM principles and theory, including advantages over intensity-based fluorescence measurements. Fundamentals of FLIM instrumentation in time- and frequency-domains are summarized, along with recent developments. Image segmentation and analysis strategies that quantify spatial and molecular features of cellular heterogeneity are reviewed. Finally, representative applications are provided including high-resolution FLIM of cell- and organelle-level molecular changes, use of exogenous and endogenous fluorophores, and imaging protein-protein interactions with Förster resonance energy transfer (FRET). Advantages and limitations of FLIM are also discussed. CONCLUSIONS FLIM is advantageous for probing molecular environments of fluorophores to inform on fluorophore behavior that cannot be elucidated with intensity measurements alone. Development of FLIM technologies, analysis, and applications will further advance biological research and clinical assessments.
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Affiliation(s)
- Rupsa Datta
- Morgridge Institute for Research, Madison, Wisconsin, United States
| | - Tiffany M. Heaster
- Morgridge Institute for Research, Madison, Wisconsin, United States
- University of Wisconsin, Department of Biomedical Engineering, Madison, Wisconsin, United States
| | - Joe T. Sharick
- Morgridge Institute for Research, Madison, Wisconsin, United States
| | - Amani A. Gillette
- Morgridge Institute for Research, Madison, Wisconsin, United States
- University of Wisconsin, Department of Biomedical Engineering, Madison, Wisconsin, United States
| | - Melissa C. Skala
- Morgridge Institute for Research, Madison, Wisconsin, United States
- University of Wisconsin, Department of Biomedical Engineering, Madison, Wisconsin, United States
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10
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Carlon-Andres I, Padilla-Parra S. Quantitative FRET-FLIM-BlaM to Assess the Extent of HIV-1 Fusion in Live Cells. Viruses 2020; 12:E206. [PMID: 32059513 PMCID: PMC7077196 DOI: 10.3390/v12020206] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 02/06/2020] [Accepted: 02/10/2020] [Indexed: 11/16/2022] Open
Abstract
The first steps of human immunodeficiency virus (HIV) infection go through the engagement of HIV envelope (Env) with CD4 and coreceptors (CXCR4 or CCR5) to mediate viral membrane fusion between the virus and the host. New approaches are still needed to better define both the molecular mechanistic underpinnings of this process but also the point of fusion and its kinetics. Here, we have developed a new method able to detect and quantify HIV-1 fusion in single live cells. We present a new approach that employs fluorescence lifetime imaging microscopy (FLIM) to detect Förster resonance energy transfer (FRET) when using the β-lactamase (BlaM) assay. This novel approach allows comparing different populations of single cells regardless the concentration of CCF2-AM FRET reporter in each cell, and more importantly, is able to determine the relative amount of viruses internalized per cell. We have applied this approach in both reporter TZM-bl cells and primary T cell lymphocytes.
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Affiliation(s)
| | - Sergi Padilla-Parra
- Division of Structural Biology, University of Oxford, Wellcome Centre for Human Genetics, Headington, Oxford OX3 7BN, UK;
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11
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McCullock TW, MacLean DM, Kammermeier PJ. Comparing the performance of mScarlet-I, mRuby3, and mCherry as FRET acceptors for mNeonGreen. PLoS One 2020; 15:e0219886. [PMID: 32023253 PMCID: PMC7001971 DOI: 10.1371/journal.pone.0219886] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 01/23/2020] [Indexed: 11/19/2022] Open
Abstract
Förster Resonance Energy Transfer (FRET) has become an immensely powerful tool to profile intra- and inter-molecular interactions. Through fusion of genetically encoded fluorescent proteins (FPs) researchers have been able to detect protein oligomerization, receptor activation, and protein translocation among other biophysical phenomena. Recently, two bright monomeric red fluorescent proteins, mRuby3 and mScarlet-I, have been developed. These proteins offer much improved physical properties compared to previous generations of monomeric red FPs that should help facilitate more general adoption of Green/Red FRET. Here we assess the ability of these two proteins, along with mCherry, to act as a FRET acceptor for the bright, monomeric, green-yellow FP mNeonGreen using intensiometric FRET and 2-photon Fluorescent Lifetime Imaging Microscopy (FLIM) FRET techniques. We first determined that mNeonGreen was a stable donor for 2-photon FLIM experiments under a variety of imaging conditions. We then tested the red FP's ability to act as FRET acceptors using mNeonGreen-Red FP tandem construct. With these constructs we found that mScarlet-I and mCherry are able to efficiently FRET with mNeonGreen in spectroscopic and FLIM FRET. In contrast, mNeonGreen and mRuby3 FRET with a much lower efficiency than predicted in these same assays. We explore possible explanations for this poor performance and determine mRuby3's protein maturation properties are a major contributor. Overall, we find that mNeonGreen is an excellent FRET donor, and both mCherry and mScarlet-I, but not mRuby3, act as practical FRET acceptors, with the brighter mScarlet-I out performing mCherry in intensiometric studies, but mCherry out performing mScarlet-I in instances where consistent efficiency in a population is critical.
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Affiliation(s)
- Tyler W. McCullock
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - David M. MacLean
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Paul J. Kammermeier
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, United States of America
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12
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Tardif C, Nadeau G, Labrecque S, Côté D, Lavoie-Cardinal F, De Koninck P. Fluorescence lifetime imaging nanoscopy for measuring Förster resonance energy transfer in cellular nanodomains. NEUROPHOTONICS 2019; 6:015002. [PMID: 30746389 PMCID: PMC6354015 DOI: 10.1117/1.nph.6.1.015002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 11/28/2018] [Indexed: 05/08/2023]
Abstract
Microscopy methods used to measure Förster resonance energy transfer (FRET) between fluorescently labeled proteins can provide information on protein interactions in cells. However, these methods are diffraction-limited, thus do not enable the resolution of the nanodomains in which such interactions occur in cells. To overcome this limitation, we assess FRET with an imaging system combining fluorescence lifetime imaging microscopy with stimulated emission depletion, termed fluorescence lifetime imaging nanoscopy (FLIN). The resulting FRET-FLIN approach utilizes immunolabeling of proteins in fixed cultured neurons. We demonstrate the capacity to discriminate nanoclusters of synaptic proteins exhibiting variable degrees of interactions with labeled binding partners inside dendritic spines of hippocampal neurons. This method enables the investigation of FRET within nanodomains of cells, approaching the scale of molecular signaling.
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Affiliation(s)
| | | | | | - Daniel Côté
- CERVO Brain Research Center, Québec (QC), Canada
- Université Laval, Département de physique, de génie physique et d’optique, Québec (QC), Canada
| | | | - Paul De Koninck
- CERVO Brain Research Center, Québec (QC), Canada
- Université Laval, Département de biochimie, de microbiologie et de bio-informatique, Québec (QC), Canada
- Address all correspondence to Paul De Koninck, E-mail:
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13
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Alexandrov Y, Nikolic DS, Dunsby C, French PMW. Quantitative time domain analysis of lifetime-based Förster resonant energy transfer measurements with fluorescent proteins: Static random isotropic fluorophore orientation distributions. JOURNAL OF BIOPHOTONICS 2018; 11:e201700366. [PMID: 29582566 DOI: 10.1002/jbio.201700366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 03/23/2018] [Indexed: 06/08/2023]
Abstract
Förster resonant energy transfer (FRET) measurements are widely used to obtain information about molecular interactions and conformations through the dependence of FRET efficiency on the proximity of donor and acceptor fluorophores. Fluorescence lifetime measurements can provide quantitative analysis of FRET efficiency and interacting population fraction. Many FRET experiments exploit the highly specific labelling of genetically expressed fluorescent proteins, applicable in live cells and organisms. Unfortunately, the typical assumption of fast randomization of fluorophore orientations in the analysis of fluorescence lifetime-based FRET readouts is not valid for fluorescent proteins due to their slow rotational mobility compared to their upper state lifetime. Here, previous analysis of effectively static isotropic distributions of fluorophore dipoles on FRET measurements is incorporated into new software for fitting donor emission decay profiles. Calculated FRET parameters, including molar population fractions, are compared for the analysis of simulated and experimental FRET data under the assumption of static and dynamic fluorophores and the intermediate regimes between fully dynamic and static fluorophores, and mixtures within FRET pairs, is explored. Finally, a method to correct the artefact resulting from fitting the emission from static FRET pairs with isotropic angular distributions to the (incorrect) typically assumed dynamic FRET decay model is presented.
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Affiliation(s)
- Yuriy Alexandrov
- Photonics Group, Department of Physics, Imperial College London, London, UK
- Light Microscopy, Francis Crick Institute, London, UK
| | - Dino S Nikolic
- Quantum Physics and Information Technology Group, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Christopher Dunsby
- Photonics Group, Department of Physics, Imperial College London, London, UK
- Light Microscopy, Francis Crick Institute, London, UK
- Centre for Pathology, Imperial College London, London, UK
| | - Paul M W French
- Photonics Group, Department of Physics, Imperial College London, London, UK
- Light Microscopy, Francis Crick Institute, London, UK
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Manzoor O, Soleja N, Mohsin M. Nanoscale gizmos - the novel fluorescent probes for monitoring protein activity. Biochem Eng J 2018; 133:83-95. [PMID: 32518506 PMCID: PMC7270366 DOI: 10.1016/j.bej.2018.02.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 12/27/2017] [Accepted: 02/06/2018] [Indexed: 11/15/2022]
Abstract
Genetically-encoded FRET, organic dye, QD based sensors. Real-time monitoring of the respective metabolite level at sub cellular level. Spatio temporal resolution of the fluorophores by low intensity light. Monitoring of various metabolite levels in any cell type prokaryotic and eukaryotic as well. Functional analysis of the role of proteases in several diseases.
Nanobiotechnology has emerged inherently as an interdisciplinary field, with collaborations from researchers belonging to diverse backgrounds like molecular biology, materials science and organic chemistry. Till the current times, researchers have been able to design numerous types of nanoscale fluorescent tool kits for monitoring protein–protein interactions through real time cellular imagery in a fluorescence microscope. It is apparent that supplementing any protein of interest with a fluorescence habit traces its function and regulation within a cell. Our review therefore highlights the application of several fluorescent probes such as molecular organic dyes, quantum dots (QD) and fluorescent proteins (FPs) to determine activity state, expression and localization of proteins in live and fixed cells. The focus is on Fluorescence Resonance Energy Transfer (FRET) based nanosensors that have been developed by researchers to visualize and monitor protein dynamics and quantify metabolites of diverse nature. FRET based toolkits permit the resolution of ambiguities that arise due to the rotation of sensor molecules and flexibility of the probe. Achievements of live cell imaging and efficient spatiotemporal resolution however have been possible only with the advent of fluorescence microscopic technology, equipped with precisely sensitive automated softwares.
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15
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de Las Heras-Martínez G, Andrieu J, Larijani B, Requejo-Isidro J. Quantifying intracellular equilibrium dissociation constants using single-channel time-resolved FRET. JOURNAL OF BIOPHOTONICS 2018; 11:e201600272. [PMID: 28485056 DOI: 10.1002/jbio.201600272] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 02/20/2017] [Accepted: 02/23/2017] [Indexed: 06/07/2023]
Abstract
Quantification of the intracellular equilibrium dissociation constant of the interaction, Kd , is challenging due to the variability of the relative concentrations of the interacting proteins in the cell. Fluorescence lifetime imaging microscopy (FLIM) of the donor provides an accurate measurement of the molecular fraction of donor involved in FRET, but the fraction of bound acceptor is also needed to reliably estimate Kd . We present a method that exploits the spectroscopic properties of the widely used eGFP - mCherry FRET pair to rigorously determine the intracellular Kd based on imaging the fluorescence lifetime of only the donor (single-channel FLIM). We have assessed the effect of incomplete labelling and determined its range of application for different Kd using Monte Carlo simulations. We have demonstrated this method estimating the intracellular Kd for the homodimerisaton of the oncogenic protein 3-phosphoinositide-dependent kinase 1 (PDK1) in different cell lines and conditions, revealing a competitive mechanism for its regulation. The measured intracellular Kd was validated against in-vitro data. This method provides an accurate and generic tool to quantify protein interactions in situ.
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Affiliation(s)
| | - Josu Andrieu
- Instituto Biofisika (CSIC, UPV/EHU), Barrio de Sarriena s/n, 48940, Leioa, Spain
| | - Banafshé Larijani
- Instituto Biofisika (CSIC, UPV/EHU), Barrio de Sarriena s/n, 48940, Leioa, Spain
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Instituto Biofisika (CSIC, UPV/EHU) and Research Centre for Experimental Marine Biology and Biotechnology (PiE), University of the Basque Country (UPV/EHU), Leioa, 48940, Spain
| | - Jose Requejo-Isidro
- Instituto Biofisika (CSIC, UPV/EHU), Barrio de Sarriena s/n, 48940, Leioa, Spain
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16
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GPI-anchored proteins are confined in subdiffraction clusters at the apical surface of polarized epithelial cells. Biochem J 2017; 474:4075-4090. [PMID: 29046391 PMCID: PMC5712066 DOI: 10.1042/bcj20170582] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/19/2017] [Accepted: 10/17/2017] [Indexed: 11/28/2022]
Abstract
Spatio-temporal compartmentalization of membrane proteins is critical for the regulation of diverse vital functions in eukaryotic cells. It was previously shown that, at the apical surface of polarized MDCK cells, glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) are organized in small cholesterol-independent clusters of single GPI-AP species (homoclusters), which are required for the formation of larger cholesterol-dependent clusters formed by multiple GPI-AP species (heteroclusters). This clustered organization is crucial for the biological activities of GPI-APs; hence, understanding the spatio-temporal properties of their membrane organization is of fundamental importance. Here, by using direct stochastic optical reconstruction microscopy coupled to pair correlation analysis (pc-STORM), we were able to visualize and measure the size of these clusters. Specifically, we show that they are non-randomly distributed and have an average size of 67 nm. We also demonstrated that polarized MDCK and non-polarized CHO cells have similar cluster distribution and size, but different sensitivity to cholesterol depletion. Finally, we derived a model that allowed a quantitative characterization of the cluster organization of GPI-APs at the apical surface of polarized MDCK cells for the first time. Experimental FRET (fluorescence resonance energy transfer)/FLIM (fluorescence-lifetime imaging microscopy) data were correlated to the theoretical predictions of the model.
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17
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Dynamin-2 Stabilizes the HIV-1 Fusion Pore with a Low Oligomeric State. Cell Rep 2017; 18:443-453. [PMID: 28076788 PMCID: PMC5263234 DOI: 10.1016/j.celrep.2016.12.032] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 10/14/2016] [Accepted: 12/12/2016] [Indexed: 11/22/2022] Open
Abstract
One of the key research areas surrounding HIV-1 concerns the regulation of the fusion event that occurs between the virus particle and the host cell during entry. Even if it is universally accepted that the large GTPase dynamin-2 is important during HIV-1 entry, its exact role during the first steps of HIV-1 infection is not well characterized. Here, we have utilized a multidisciplinary approach to study the DNM2 role during fusion of HIV-1 in primary resting CD4 T and TZM-bl cells. We have combined advanced light microscopy and functional cell-based assays to experimentally assess the role of dynamin-2 during these processes. Overall, our data suggest that dynamin-2, as a tetramer, might help to establish hemi-fusion and stabilizes the pore during HIV-1 fusion. DNM2 is crucial for HIV-1 fusion in T Cells and reporter cells DNM2 is not necessarily linked with endocytosis DNM2 tetramer stabilizes the HIV-1 fusion pore
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18
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Tomczak AP, Fernández-Trillo J, Bharill S, Papp F, Panyi G, Stühmer W, Isacoff EY, Pardo LA. A new mechanism of voltage-dependent gating exposed by K V10.1 channels interrupted between voltage sensor and pore. J Gen Physiol 2017; 149:577-593. [PMID: 28360219 PMCID: PMC5412533 DOI: 10.1085/jgp.201611742] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/09/2017] [Accepted: 02/16/2017] [Indexed: 12/03/2022] Open
Abstract
A linker that connects the voltage-sensing domain and pore domain in voltage-gated K+ channels is thought to provide coupling during gating, but this view has been challenged in KCNH channels. Tomczak et al. investigate gating in KV10.1 channels with disrupted linkers and reveal multiple mechanisms. Voltage-gated ion channels couple transmembrane potential changes to ion flow. Conformational changes in the voltage-sensing domain (VSD) of the channel are thought to be transmitted to the pore domain (PD) through an α-helical linker between them (S4–S5 linker). However, our recent work on channels disrupted in the S4–S5 linker has challenged this interpretation for the KCNH family. Furthermore, a recent single-particle cryo-electron microscopy structure of KV10.1 revealed that the S4–S5 linker is a short loop in this KCNH family member, confirming the need for an alternative gating model. Here we use “split” channels made by expression of VSD and PD as separate fragments to investigate the mechanism of gating in KV10.1. We find that disruption of the covalent connection within the S4 helix compromises the ability of channels to close at negative voltage, whereas disconnecting the S4–S5 linker from S5 slows down activation and deactivation kinetics. Surprisingly, voltage-clamp fluorometry and MTS accessibility assays show that the motion of the S4 voltage sensor is virtually unaffected when VSD and PD are not covalently bound. Finally, experiments using constitutively open PD mutants suggest that the presence of the VSD is structurally important for the conducting conformation of the pore. Collectively, our observations offer partial support to the gating model that assumes that an inward motion of the C-terminal S4 helix, rather than the S4–S5 linker, closes the channel gate, while also suggesting that control of the pore by the voltage sensor involves more than one mechanism.
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Affiliation(s)
- Adam P Tomczak
- Oncophysiology Group, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany
| | - Jorge Fernández-Trillo
- Oncophysiology Group, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany
| | - Shashank Bharill
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720
| | - Ferenc Papp
- Department of Biophysics and Cell Biology, University of Debrecen, 4032 Debrecen, Hungary.,MTA-DE-NAP B Ion Channel Structure-Function Research Group, RCMM, University of Debrecen, 4032 Debrecen, Hungary
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, University of Debrecen, 4032 Debrecen, Hungary.,MTA-DE-NAP B Ion Channel Structure-Function Research Group, RCMM, University of Debrecen, 4032 Debrecen, Hungary
| | - Walter Stühmer
- Department of Molecular Biology of Neuronal Signals, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany
| | - Ehud Y Isacoff
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720
| | - Luis A Pardo
- Oncophysiology Group, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany
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Multiplexing PKA and ERK1&2 kinases FRET biosensors in living cells using single excitation wavelength dual colour FLIM. Sci Rep 2017; 7:41026. [PMID: 28106114 PMCID: PMC5247693 DOI: 10.1038/srep41026] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 12/14/2016] [Indexed: 02/04/2023] Open
Abstract
Monitoring of different signalling enzymes in a single assay using multiplex biosensing provides a multidimensional workspace to elucidate biological processes, signalling pathway crosstalk, and determine precise sequence of events at the single living cell level. In this study, we interrogate the complexity in cAMP/PKA-MAPK/ERK1&2 crosstalk by using multi-parameter biosensing experiments to correlate biochemical activities simultaneously in time and space. Using a single excitation wavelength dual colour FLIM method we are able to detect fluorescence lifetime images of two donors to simultaneously measure PKA and ERK1&2 kinase activities in the same cellular localization by using FRET biosensors. To this end, we excite two FRET donors mTFP1 and LSSmOrange with a 440 nm wavelength and we alleviate spectral bleed-through associated limitations with the very dim-fluorescent acceptor ShadowG for mTFP1 and the red-shifted mKate2 for LSSmOrange. The simultaneous recording of PKA and ERK1&2 kinase activities reveals concomitant EGF-mediated activations of both kinases in HeLa cells. Under these conditions the subsequent Forskolin-induced cAMP release reverses the transient increase of EGF-mediated ERK1&2 kinase activity while reinforcing PKA activation. Here we propose a validated methodology for multiparametric kinase biosensing in living cells using FRET-FLIM.
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20
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Błasiak E, Łukasiewicz S, Szafran-Pilch K, Dziedzicka-Wasylewska M. Genetic variants of dopamine D2 receptor impact heterodimerization with dopamine D1 receptor. Pharmacol Rep 2016; 69:235-241. [PMID: 28119185 DOI: 10.1016/j.pharep.2016.10.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 10/25/2016] [Accepted: 10/26/2016] [Indexed: 01/14/2023]
Abstract
BACKGROUND The human dopamine D2 receptor gene has three polymorphic variants that alter its amino acid sequence: alanine substitution by valine in position 96 (V96A), proline substitution by serine in position 310 (P310S) and serine substitution by cysteine in position 311 (S311C). Their functional role has never been the object of extensive studies, even though there is some evidence that their occurrence correlates with schizophrenia. METHODS The HEK293 cell line was transfected with dopamine D1 and D2 receptors (or genetic variants of the D2 receptor), coupled to fluorescent proteins which allowed us to measure the extent of dimerization of these receptors, using a highly advanced biophysical approach (FLIM-FRET). Additionally, Fluoro-4 AM was used to examine changes in the level of calcium release after ligand stimulation of cells expressing different combinations of dopamine receptors. RESULTS Using FLIM-FRET experiments we have shown that in HEK 293 expressing dopamine receptors, polymorphic mutations in the D2 receptor play a role in dimmer formation with the dopamine D1 receptor. The association level of dopamine receptors is affected by ligand administration, with variable effects depending on polymorphic variant of the D2 dopamine receptor. We have found that the level of heteromer formation is reflected by calcium ion release after ligand stimulation and have observed variations of this effect dependent on the polymorphic variant and the ligand. CONCLUSION The data presented in this paper support the hypothesis on the role of calcium signaling regulated by the D1-D2 heteromer which may be of relevance for schizophrenia etiology.
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Affiliation(s)
- Ewa Błasiak
- Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
| | - Sylwia Łukasiewicz
- Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
| | | | - Marta Dziedzicka-Wasylewska
- Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland; Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland.
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21
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Bertolin G, Sizaire F, Herbomel G, Reboutier D, Prigent C, Tramier M. A FRET biosensor reveals spatiotemporal activation and functions of aurora kinase A in living cells. Nat Commun 2016; 7:12674. [PMID: 27624869 PMCID: PMC5027284 DOI: 10.1038/ncomms12674] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 07/21/2016] [Indexed: 12/20/2022] Open
Abstract
Overexpression of AURKA is a major hallmark of epithelial cancers. It encodes the multifunctional serine/threonine kinase aurora A, which is activated at metaphase and is required for cell cycle progression; assessing its activation in living cells is mandatory for next-generation drug design. We describe here a Förster's resonance energy transfer (FRET) biosensor detecting the conformational changes of aurora kinase A induced by its autophosphorylation on Thr288. The biosensor functionally replaces the endogenous kinase in cells and allows the activation of the kinase to be followed throughout the cell cycle. Inhibiting the catalytic activity of the kinase prevents the conformational changes of the biosensor. Using this approach, we discover that aurora kinase A activates during G1 to regulate the stability of microtubules in cooperation with TPX2 and CEP192. These results demonstrate that the aurora kinase A biosensor is a powerful tool to identify new regulatory pathways controlling aurora kinase A activation.
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Affiliation(s)
- Giulia Bertolin
- CNRS, UMR 6290, Rennes 35043, France
- Université de Rennes 1, Institut de Génétique et Développement de Rennes, Rennes 35043, France
| | - Florian Sizaire
- CNRS, UMR 6290, Rennes 35043, France
- Université de Rennes 1, Institut de Génétique et Développement de Rennes, Rennes 35043, France
| | - Gaëtan Herbomel
- CNRS, UMR 6290, Rennes 35043, France
- Université de Rennes 1, Institut de Génétique et Développement de Rennes, Rennes 35043, France
| | - David Reboutier
- CNRS, UMR 6290, Rennes 35043, France
- Université de Rennes 1, Institut de Génétique et Développement de Rennes, Rennes 35043, France
- Equipe labéllisée Ligue Contre Le Cancer 2014–2016, Rennes 35043, France
| | - Claude Prigent
- CNRS, UMR 6290, Rennes 35043, France
- Université de Rennes 1, Institut de Génétique et Développement de Rennes, Rennes 35043, France
- Equipe labéllisée Ligue Contre Le Cancer 2014–2016, Rennes 35043, France
| | - Marc Tramier
- CNRS, UMR 6290, Rennes 35043, France
- Université de Rennes 1, Institut de Génétique et Développement de Rennes, Rennes 35043, France
- Microscopy Rennes Imaging Centre, Biosit, Université de Rennes 1, Rennes 35043, France
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22
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Łukasiewicz S, Błasiak E, Szafran-Pilch K, Dziedzicka-Wasylewska M. Dopamine D2 and serotonin 5-HT1A receptor interaction in the context of the effects of antipsychotics - in vitro studies. J Neurochem 2016; 137:549-60. [PMID: 26876117 DOI: 10.1111/jnc.13582] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 02/04/2016] [Accepted: 02/05/2016] [Indexed: 12/11/2022]
Abstract
The serotonin 5-HT1A receptor (5-HT1 A R) and dopamine D2 receptor (D2 R) have been implicated as important sites of action in antipsychotics. Several lines of evidence indicate the key role of G protein-coupled receptors (GPCRs) heteromers in pathophysiology of schizophrenia and highlight these complexes as novel drug targets. Because heterodimers can form only on those cells co-expressing constituent receptors, they present a target of high pharmacological specificity in the context of biochemical effects induced by antipsychotic drugs. In studies conducted in the HEK 293 cell line, we demonstrated that 5-HT1 A R and D2 R are able to form constitutive heterodimers, and antipsychotic drugs (clozapine, olanzapine, aripiprazole, and lurasidone) enhanced this process, with clozapine being most effective. Various functional tests (cAMP and IP1 as well as ERK activation) indicated that the drugs had different effects on signal transduction by the heteromer. Interestingly, co-incubation of heterodimer-expressing HEK 293 cells with clozapine and the 5-HT1 A R agonist 8-OH DPAT potentiated post-synaptic effects, especially with respect to ERK activation. Our results indicate that the D2 -5-HT1A complex possesses biochemical, pharmacological, and functional properties distinct from those of mono- and homomers. This result has implications for the development of improved pharmacotherapy for schizophrenia or other disorders (activating the heteromer might be cognitive enhancing, since it is expressed in frontal cortex) through the specific targeting of heterodimers. We reported the constitutive formation of D2 -5-HT1A heteromers, which possess biochemical, pharmacological, and functional properties distinct from those of mono- and homomers, as revealed by antipsychotics action. We also showed that these two receptors are co-expressed in mouse cortical neurons; therefore their potential to heterodimerize may comprise an essential target for the development of novel strategies for schizophrenia treatment.
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Affiliation(s)
- Sylwia Łukasiewicz
- Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Ewa Błasiak
- Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | | | - Marta Dziedzicka-Wasylewska
- Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
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Suzuki M, Sakata I, Sakai T, Tomioka H, Nishigaki K, Tramier M, Coppey-Moisan M. A high-throughput direct fluorescence resonance energy transfer-based assay for analyzing apoptotic proteases using flow cytometry and fluorescence lifetime measurements. Anal Biochem 2015; 491:10-7. [DOI: 10.1016/j.ab.2015.08.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 08/11/2015] [Accepted: 08/14/2015] [Indexed: 01/27/2023]
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24
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Jones DM, Padilla-Parra S. Imaging real-time HIV-1 virion fusion with FRET-based biosensors. Sci Rep 2015; 5:13449. [PMID: 26300212 PMCID: PMC4547133 DOI: 10.1038/srep13449] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 07/28/2015] [Indexed: 11/08/2022] Open
Abstract
We have produced a novel, simple and rapid method utilising genetically encodable FRET-based biosensors to permit the detection of HIV-1 virion fusion in living cells. These biosensors show high sensitivity both spatially and temporally, and allow the real-time recovery of HIV-1 fusion kinetics in both single cells and cell populations simultaneously.
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Affiliation(s)
- Daniel M. Jones
- Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford OX3 7BN, UK
| | - Sergi Padilla-Parra
- Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford OX3 7BN, UK
- Cellular Imaging Core, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
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25
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George Abraham B, Sarkisyan KS, Mishin AS, Santala V, Tkachenko NV, Karp M. Fluorescent Protein Based FRET Pairs with Improved Dynamic Range for Fluorescence Lifetime Measurements. PLoS One 2015; 10:e0134436. [PMID: 26237400 PMCID: PMC4523203 DOI: 10.1371/journal.pone.0134436] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 07/09/2015] [Indexed: 11/18/2022] Open
Abstract
Fluorescence Resonance Energy Transfer (FRET) using fluorescent protein variants is widely used to study biochemical processes in living cells. FRET detection by fluorescence lifetime measurements is the most direct and robust method to measure FRET. The traditional cyan-yellow fluorescent protein based FRET pairs are getting replaced by green-red fluorescent protein variants. The green-red pair enables excitation at a longer wavelength which reduces cellular autofluorescence and phototoxicity while monitoring FRET. Despite the advances in FRET based sensors, the low FRET efficiency and dynamic range still complicates their use in cell biology and high throughput screening. In this paper, we utilized the higher lifetime of NowGFP and screened red fluorescent protein variants to develop FRET pairs with high dynamic range and FRET efficiency. The FRET variations were analyzed by proteolytic activity and detected by steady-state and time-resolved measurements. Based on the results, NowGFP-tdTomato and NowGFP-mRuby2 have shown high potentials as FRET pairs with large fluorescence lifetime dynamic range. The in vitro measurements revealed that the NowGFP-tdTomato has the highest Förster radius for any fluorescent protein based FRET pairs yet used in biological studies. The developed FRET pairs will be useful for designing FRET based sensors and studies employing Fluorescence Lifetime Imaging Microscopy (FLIM).
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Affiliation(s)
- Bobin George Abraham
- Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, 33101, Tampere, Finland
| | - Karen S. Sarkisyan
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - Alexander S. Mishin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - Ville Santala
- Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, 33101, Tampere, Finland
| | - Nikolai V. Tkachenko
- Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, 33101, Tampere, Finland
| | - Matti Karp
- Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, 33101, Tampere, Finland
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Abstract
Cells generate and experience mechanical forces that may shape tissues and regulate signaling pathways in a variety of physiological or pathological situations. How forces propagate and transduce signals at the molecular level is poorly understood. The advent of FRET-based Molecular Tension Microscopy now allows to achieve mechanical force measurements at a molecular scale with molecular specificity in situ, and thereby better understand the mechanical architecture of cells and tissues, and mechanotransduction pathways. In this review, we will first expose the basic principles of FRET-based MTM and its various incarnations. We will describe different ways of measuring FRET, their advantages and drawbacks. Then, throughout the range of proteins of interest, cells and organisms to which it has been applied, we will review the tests developed to validate the approach, how molecular tension was related to cell functions, and conclude with possible developments and offshoots.
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Affiliation(s)
- Charlène Gayrard
- Institut Jacques Monod, Unité Mixe de Recherche 7592, Centre national de la recherche scientifique, Université Paris-Diderot, Paris 75013, France
| | - Nicolas Borghi
- Institut Jacques Monod, Unité Mixe de Recherche 7592, Centre national de la recherche scientifique, Université Paris-Diderot, Paris 75013, France.
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Optimizing fluorescent protein trios for 3-Way FRET imaging of protein interactions in living cells. Sci Rep 2015; 5:10270. [PMID: 26130463 PMCID: PMC4487001 DOI: 10.1038/srep10270] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 04/07/2015] [Indexed: 12/29/2022] Open
Abstract
Powerful new methods have extended FRET microscopy to the imaging of three or more interacting proteins inside living cells. Here, we compared widely available fluorescent proteins to find the best trio for 3-Way FRET imaging. We focused on readily available cyan, yellow, and red proteins that have high quantum yields, large extinction coefficients and good photostability, which defined these candidate proteins: CyPet/mTFP1/mTurqoise2, mCitrine/YPet, and TagRFP/TagRFPt/mRuby2/mCherry. By taking advantage of the high structural similarity across the fluorescent proteins, we generated structurally similar, but photophysically distinct donor/acceptor and triple fluorophore fusion proteins and measured their FRET efficiencies inside living cells. Surprisingly, their published photophysical parameters and calculated Förster distances did not predict the best combinations of FPs. Using cycloheximide to inhibit protein synthesis, we found that the different FP maturation rates had a strong effect on the FRET efficiency. This effect was pronounced when comparing rapidly maturing yellow and slowly maturing red FPs. We found that red FPs with inferior photophysics gave superior FRET efficiencies because of faster maturation rates. Based on combined metrics for the FRET efficiency, fluorophore photophysics and fluorophore maturation we determined that Turqoise2, YPet and Cherry were the best available FPs for live cell 3-Way FRET measurements.
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Padilla-Parra S, Audugé N, Tramier M, Coppey-Moisan M. Time-domain fluorescence lifetime imaging microscopy: a quantitative method to follow transient protein-protein interactions in living cells. Cold Spring Harb Protoc 2015; 2015:508-21. [PMID: 26034312 DOI: 10.1101/pdb.top086249] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Quantitative analysis in Förster resonance energy transfer (FRET) imaging studies of protein-protein interactions within live cells is still a challenging issue. Many cellular biology applications aim at the determination of the space and time variations of the relative amount of interacting fluorescently tagged proteins occurring in cells. This relevant quantitative parameter can be, at least partially, obtained at a pixel-level resolution by using fluorescence lifetime imaging microscopy (FLIM). Indeed, fluorescence decay analysis of a two-component system (FRET and no FRET donor species), leads to the intrinsic FRET efficiency value (E) and the fraction of the donor-tagged protein that undergoes FRET (fD). To simultaneously obtain fD and E values from a two-exponential fit, data must be acquired with a high number of photons, so that the statistics are robust enough to reduce fitting ambiguities. This is a time-consuming procedure. However, when fast-FLIM acquisitions are used to monitor dynamic changes in protein-protein interactions at high spatial and temporal resolutions in living cells, photon statistics and time resolution are limited. In this case, fitting procedures are unreliable, even for single lifetime donors. We introduce the concept of a minimal fraction of donor molecules involved in FRET (mfD), obtained from the mathematical minimization of fD. Here, we discuss different FLIM techniques and the compromises that must be made between precision and time invested in acquiring FLIM measurements. We show that mfD constitutes an interesting quantitative parameter for fast FLIM because it gives quantitative information about transient interactions in live cells.
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Abstract
![]()
Exploration of protein function and
interaction is critical for
discovering links among genomics, proteomics, and disease state; yet,
the immense complexity of proteomics found in biological systems currently
limits our investigational capacity. Although affinity and autofluorescent
tags are widely employed for protein analysis, these methods have
been met with limited success because they lack specificity and require
multiple fusion tags and genetic constructs. As an alternative approach,
the innovative HaloTag protein fusion platform allows protein function
and interaction to be comprehensively analyzed using a single genetic
construct with multiple capabilities. This is accomplished using a
simplified process, in which a variable HaloTag ligand binds rapidly
to the HaloTag protein (usually linked to the protein of interest)
with high affinity and specificity. In this review, we examine all
current applications of the HaloTag technology platform for biomedical
applications, such as the study of protein isolation and purification,
protein function, protein–protein and protein–DNA interactions,
biological assays, in vitro cellular imaging, and in vivo molecular imaging. In addition, novel uses of the
HaloTag platform are briefly discussed along with potential future
applications.
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Affiliation(s)
- Christopher G England
- †Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Haiming Luo
- ‡Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Weibo Cai
- †Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States.,‡Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States.,§University of Wisconsin Carbone Cancer Center, Madison, Wisconsin 53705, United States
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Detert Oude Weme RGJ, Kovács ÁT, de Jong SJG, Veening JW, Siebring J, Kuipers OP. Single cell FRET analysis for the identification of optimal FRET-pairs in Bacillus subtilis using a prototype MEM-FLIM system. PLoS One 2015; 10:e0123239. [PMID: 25886351 PMCID: PMC4401445 DOI: 10.1371/journal.pone.0123239] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/01/2015] [Indexed: 11/21/2022] Open
Abstract
Protein-protein interactions can be studied in vitro, e.g. with bacterial or yeast two-hybrid systems or surface plasmon resonance. In contrast to in vitro techniques, in vivo studies of protein-protein interactions allow examination of spatial and temporal behavior of such interactions in their native environment. One approach to study protein-protein interactions in vivo is via Förster Resonance Energy Transfer (FRET). Here, FRET efficiency of selected FRET-pairs was studied at the single cell level using sensitized emission and Frequency Domain-Fluorescence Lifetime Imaging Microscopy (FD-FLIM). For FRET-FLIM, a prototype Modulated Electron-Multiplied FLIM system was used, which is, to the best of our knowledge, the first account of Frequency Domain FLIM to analyze FRET in single bacterial cells. To perform FRET-FLIM, we first determined and benchmarked the best fluorescent protein-pair for FRET in Bacillus subtilis using a novel BglBrick-compatible integration vector. We show that GFP-tagRFP is an excellent donor-acceptor pair for B. subtilis in vivo FRET studies. As a proof of concept, selected donor and acceptor fluorescent proteins were fused using a linker that contained a tobacco etch virus (TEV)-protease recognition sequence. Induction of TEV-protease results in loss of FRET efficiency and increase in fluorescence lifetime. The loss of FRET efficiency after TEV induction can be followed in time in single cells via time-lapse microscopy. This work will facilitate future studies of in vivo dynamics of protein complexes in single B. subtilis cells.
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Affiliation(s)
- Ruud G. J. Detert Oude Weme
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Ákos T. Kovács
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, 9747 AG Groningen, The Netherlands
| | | | - Jan-Willem Veening
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Jeroen Siebring
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Oscar P. Kuipers
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, 9747 AG Groningen, The Netherlands
- * E-mail:
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31
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Kitamura A, Nagata K, Kinjo M. Conformational analysis of misfolded protein aggregation by FRET and live-cell imaging techniques. Int J Mol Sci 2015; 16:6076-92. [PMID: 25785563 PMCID: PMC4394520 DOI: 10.3390/ijms16036076] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 03/05/2015] [Accepted: 03/11/2015] [Indexed: 12/18/2022] Open
Abstract
Cellular homeostasis is maintained by several types of protein machinery, including molecular chaperones and proteolysis systems. Dysregulation of the proteome disrupts homeostasis in cells, tissues, and the organism as a whole, and has been hypothesized to cause neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD). A hallmark of neurodegenerative disorders is formation of ubiquitin-positive inclusion bodies in neurons, suggesting that the aggregation process of misfolded proteins changes during disease progression. Hence, high-throughput determination of soluble oligomers during the aggregation process, as well as the conformation of sequestered proteins in inclusion bodies, is essential for elucidation of physiological regulation mechanism and drug discovery in this field. To elucidate the interaction, accumulation, and conformation of aggregation-prone proteins, in situ spectroscopic imaging techniques, such as Förster/fluorescence resonance energy transfer (FRET), fluorescence correlation spectroscopy (FCS), and bimolecular fluorescence complementation (BiFC) have been employed. Here, we summarize recent reports in which these techniques were applied to the analysis of aggregation-prone proteins (in particular their dimerization, interactions, and conformational changes), and describe several fluorescent indicators used for real-time observation of physiological states related to proteostasis.
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Affiliation(s)
- Akira Kitamura
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo 001-0021, Japan.
| | - Kazuhiro Nagata
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan.
| | - Masataka Kinjo
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo 001-0021, Japan.
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Role of the nucleocapsid domain in HIV-1 Gag oligomerization and trafficking to the plasma membrane: a fluorescence lifetime imaging microscopy investigation. J Mol Biol 2015; 427:1480-1494. [PMID: 25644662 DOI: 10.1016/j.jmb.2015.01.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/26/2015] [Accepted: 01/27/2015] [Indexed: 11/20/2022]
Abstract
The Pr55 Gag of human immunodeficiency virus type 1 orchestrates viral particle assembly in producer cells, which requires the genomic RNA and a lipid membrane as scaffolding platforms. The nucleocapsid (NC) domain with its two invariant CCHC zinc fingers flanked by unfolded basic sequences is thought to direct genomic RNA selection, dimerization and packaging during virus assembly. To further investigate the role of NC domain, we analyzed the assembly of Gag with deletions in the NC domain in parallel with that of wild-type Gag using fluorescence lifetime imaging microscopy combined with Förster resonance energy transfer in HeLa cells. We found that, upon binding to nucleic acids, the NC domain promotes the formation of compact Gag oligomers in the cytoplasm. Moreover, the intracellular distribution of the population of oligomers further suggests that oligomers progressively assemble during their trafficking toward the plasma membrane (PM), but with no dramatic changes in their compact arrangement. This ultimately results in the accumulation at the PM of closely packed Gag oligomers that likely arrange in hexameric lattices, as revealed by the perfect match between the experimental Förster resonance energy transfer value and the one calculated from the structural model of Gag in immature viruses. The distal finger and flanking basic sequences, but not the proximal finger, appear to be essential for Gag oligomer compaction and membrane binding. Moreover, the full NC domain was found to be instrumental in the kinetics of Gag oligomerization and intracellular trafficking. These findings further highlight the key roles played by the NC domain in virus assembly.
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33
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Richert L, Didier P, de Rocquigny H, Mély Y. Monitoring HIV-1 Protein Oligomerization by FLIM FRET Microscopy. SPRINGER SERIES IN CHEMICAL PHYSICS 2015. [DOI: 10.1007/978-3-319-14929-5_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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34
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Cost AL, Ringer P, Chrostek-Grashoff A, Grashoff C. How to Measure Molecular Forces in Cells: A Guide to Evaluating Genetically-Encoded FRET-Based Tension Sensors. Cell Mol Bioeng 2014; 8:96-105. [PMID: 25798203 PMCID: PMC4361753 DOI: 10.1007/s12195-014-0368-1] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 11/21/2014] [Indexed: 12/16/2022] Open
Abstract
The ability of cells to sense and respond to mechanical forces is central to a wide range of biological processes and plays an important role in numerous pathologies. The molecular mechanisms underlying cellular mechanotransduction, however, have remained largely elusive because suitable methods to investigate subcellular force propagation were missing. Here, we review recent advances in the development of biosensors that allow molecular force measurements. We describe the underlying principle of currently available techniques and propose a strategy to systematically evaluate new Förster resonance energy transfer (FRET)-based biosensors.
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Affiliation(s)
- Anna-Lena Cost
- Group of Molecular Mechanotransduction, Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried, 82152 Germany
| | - Pia Ringer
- Group of Molecular Mechanotransduction, Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried, 82152 Germany
| | - Anna Chrostek-Grashoff
- Group of Molecular Mechanotransduction, Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried, 82152 Germany
| | - Carsten Grashoff
- Group of Molecular Mechanotransduction, Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried, 82152 Germany
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35
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Maximum entropy analysis of data simulations and practical aspects of time-resolved fluorescence measurements in the study of molecular interactions. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2013.12.079] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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36
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Zhao Y, Ren J, Padilla-Parra S, Fry EE, Stuart DI. Lysosome sorting of β-glucocerebrosidase by LIMP-2 is targeted by the mannose 6-phosphate receptor. Nat Commun 2014; 5:4321. [PMID: 25027712 PMCID: PMC4104448 DOI: 10.1038/ncomms5321] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 06/05/2014] [Indexed: 01/25/2023] Open
Abstract
The integral membrane protein LIMP-2 has been a paradigm for mannose 6-phosphate receptor (MPR) independent lysosomal targeting, binding to β-glucocerebrosidase (β-GCase) and directing it to the lysosome, before dissociating in the late-endosomal/lysosomal compartments. Here we report structural results illuminating how LIMP-2 binds and releases β-GCase according to changes in pH, via a histidine trigger, and suggesting that LIMP-2 localizes the ceramide portion of the substrate adjacent to the β-GCase catalytic site. Remarkably, we find that LIMP-2 bears P-Man9GlcNAc2 covalently attached to residue N325, and that it binds MPR, via mannose 6-phosphate, with a similar affinity to that observed between LIMP-2 and β-GCase. The binding sites for β-GCase and the MPR are functionally separate, so that a stable ternary complex can be formed. By fluorescence lifetime imaging microscopy, we also demonstrate that LIMP-2 interacts with MPR in living cells. These results revise the accepted view of LIMP-2-β-GCase lysosomal targeting.
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Affiliation(s)
- Yuguang Zhao
- Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford OX3 7BN, UK
- These authors contributed equally to this work
| | - Jingshan Ren
- Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford OX3 7BN, UK
- These authors contributed equally to this work
| | - Sergi Padilla-Parra
- Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford OX3 7BN, UK
| | - Elizabeth E. Fry
- Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford OX3 7BN, UK
| | - David I. Stuart
- Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford OX3 7BN, UK
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37
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Role of the nucleocapsid region in HIV-1 Gag assembly as investigated by quantitative fluorescence-based microscopy. Virus Res 2014; 193:78-88. [PMID: 25016037 DOI: 10.1016/j.virusres.2014.06.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 06/17/2014] [Accepted: 06/17/2014] [Indexed: 11/19/2022]
Abstract
The Gag precursor of HIV-1, formed of the four proteic regions matrix (MA), capsid (CA), nucleocapsid (NC) and p6, orchestrates virus morphogenesis. This complex process relies on three major interactions, NC-RNA acting as a scaffold, CA-CA and MA-membrane that targets assembly to the plasma membrane (PM). The characterization of the molecular mechanism of retroviral assembly has extensively benefited from biochemical studies and more recently an important step forward was achieved with the use of fluorescence-based techniques and fluorescently labeled viral proteins. In this review, we summarize the findings obtained with such techniques, notably quantitative-based approaches, which highlight the role of the NC region in Gag assembly.
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38
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Erdelyi M, Simon J, Barnard EA, Kaminski CF. Analyzing receptor assemblies in the cell membrane using fluorescence anisotropy imaging with TIRF microscopy. PLoS One 2014; 9:e100526. [PMID: 24945870 PMCID: PMC4063901 DOI: 10.1371/journal.pone.0100526] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 05/28/2014] [Indexed: 11/19/2022] Open
Abstract
Signaling within and between animal cells is controlled by the many receptor proteins in their membrane. They variously operate as trans-membrane monomers and homo- or hetero-dimers, and may assemble with ion-channels: analyses thereof are needed in studies of receptor actions in tissue physiology and pathology. Interactions between membrane proteins are detectable when pre-labeled with fluorophores, but a much fuller analysis is achievable via advanced optical techniques on living cells. In this context, the measurement of polarization anisotropy in the emitted fluorescence has been the least exploited. Here we demonstrate its methodology and particular advantages in the study of receptor protein assembly. Through excitation in both TIRF and EPI fluorescence illumination modes we are able to quantify and suppress contributions to the signal from extraneous intra-cellular fluorescence, and we show that the loss of fluorescence-polarization measured in membrane proteins reports on receptor protein assembly in real time. Receptor monomers and homo-dimers in the cell membrane can be analyzed quantitatively and for homo-dimers only a single fluorescent marker is needed, thus suppressing ambiguities that arise in alternative assays, which require multiple label moieties and which are thus subject to stoichiometric uncertainty.
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Affiliation(s)
- Miklos Erdelyi
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
- Analytical Science Division, National Physical Laboratory, Teddington, Middlesex, United Kingdom
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - Joseph Simon
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Eric A. Barnard
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Clemens F. Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
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Paladino S, Lebreton S, Tivodar S, Formiggini F, Ossato G, Gratton E, Tramier M, Coppey-Moisan M, Zurzolo C. Golgi sorting regulates organization and activity of GPI proteins at apical membranes. Nat Chem Biol 2014; 10:350-357. [PMID: 24681536 PMCID: PMC4027978 DOI: 10.1038/nchembio.1495] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 02/19/2014] [Indexed: 01/01/2023]
Abstract
Here we combined classical biochemistry with new biophysical approaches to study the organization of glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) with high spatial and temporal resolution at the plasma membrane of polarized epithelial cells. We show that in polarized MDCK cells, after sorting in the Golgi, each GPI-AP reaches the apical surface in homoclusters. Golgi-derived homoclusters are required for their subsequent plasma membrane organization into cholesterol-dependent heteroclusters. By contrast, in nonpolarized MDCK cells, GPI-APs are delivered to the surface as monomers in an unpolarized manner and are not able to form heteroclusters. We further demonstrate that this GPI-AP organization is regulated by the content of cholesterol in the Golgi apparatus and is required to maintain the functional state of the protein at the apical membrane. Thus, in contrast to fibroblasts, in polarized epithelial cells, a selective cholesterol-dependent sorting mechanism in the Golgi regulates both the organization and function of GPI-APs at the apical surface.
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Affiliation(s)
- Simona Paladino
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Napoli, Italy
- CEINGE Biotecnologie Avanzate, Napoli, Italy
| | - Stéphanie Lebreton
- Unité de Trafic Membranaire et Pathogénèse, Institut Pasteur, Paris, France
| | - Simona Tivodar
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Napoli, Italy
| | | | - Giulia Ossato
- Laboratory for Fluorescence Dynamics, University of California, Irvine, California
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, University of California, Irvine, California
| | - Marc Tramier
- Institut de génétique et dévelopement de Rennes, UMR 6290
| | - Maïté Coppey-Moisan
- Complexes macromoléculaires en cellules vivantes, Institut Jacques Monod, UMR 7592 CNRS, University Paris-Diderot, France
| | - Chiara Zurzolo
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Napoli, Italy
- Unité de Trafic Membranaire et Pathogénèse, Institut Pasteur, Paris, France
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40
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Hendrix J, Schrimpf W, Höller M, Lamb DC. Pulsed interleaved excitation fluctuation imaging. Biophys J 2014; 105:848-61. [PMID: 23972837 DOI: 10.1016/j.bpj.2013.05.059] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Revised: 05/16/2013] [Accepted: 05/29/2013] [Indexed: 10/26/2022] Open
Abstract
Fluorescence fluctuation imaging is a powerful means to investigate dynamics, interactions, and stoichiometry of proteins inside living cells. Pulsed interleaved excitation (PIE) is the method of nanosecond alternating excitation with time-resolved detection and allows accurate, independent, and quasi-simultaneous determination of fluorescence intensities and lifetimes of different fluorophores. In this work, we combine pulsed interleaved excitation with fluctuation imaging methods (PIE-FI) such as raster image correlation spectroscopy (RICS) or number and brightness analysis (N&B). More specifically, we show that quantitative measurements of diffusion and molecular brightness of Venus fluorescent protein (FP) can be performed in solution with PIE-RICS and compare PIE-RICS with single-point PIE-FCS measurements. We discuss the advantages of cross-talk free dual-color PIE-RICS and illustrate its proficiency by quantitatively comparing two commonly used FP pairs for dual-color microscopy, eGFP/mCherry and mVenus/mCherry. For N&B analysis, we implement dead-time correction to the PIE-FI data analysis to allow accurate molecular brightness determination with PIE-NB. We then use PIE-NB to investigate the effect of eGFP tandem oligomerization on the intracellular maturation efficiency of the fluorophore. Finally, we explore the possibilities of using the available fluorescence lifetime information in PIE-FI experiments. We perform lifetime-based weighting of confocal images, allowing us to quantitatively determine molecular concentrations from 100 nM down to <30 pM with PIE-raster lifetime image correlation spectroscopy (RLICS). We use the fluorescence lifetime information to perform a robust dual-color lifetime-based FRET analysis of tandem fluorescent protein dimers. Lastly, we investigate the use of dual-color RLICS to resolve codiffusing FRET species from non-FRET species in cells. The enhanced capabilities and quantitative results provided by PIE-FI make it a powerful method that is broadly applicable to a large number of interesting biophysical studies.
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Affiliation(s)
- Jelle Hendrix
- Department of Chemistry, Ludwig-Maximilians-Universität München, Munich, Germany.
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41
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Abstract
Förster resonance energy transfer (FRET) is a phenomenon used for bioimaging ranging from single molecules to in vivo scale. A large variety of organic dyes and fluorescent proteins are available for FRET probes. In this review, we introduce the representative pairs of FRET probes developed thus far. The efficiency of FRET is depending on the spectral overlap of donor emission and acceptor absorption, the orientation of donor and acceptor and their distance. For FRET-based indicators composed of fluorescent proteins, their orientation and dimeric property of donor and acceptor largely affect the FRET efficiency, indicating the effect for the performance of indicators. In addition, three major applications of FRET, including genetically encoded indicators, single-molecule FRET, and enhancement of chemiluminescent proteins, have been introduced and their functions have also been discussed.
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42
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Zeug A, Stawarski M, Bieganska K, Korotchenko S, Wlodarczyk J, Dityatev A, Ponimaskin E. Current microscopic methods for the neural ECM analysis. PROGRESS IN BRAIN RESEARCH 2014; 214:287-312. [PMID: 25410363 DOI: 10.1016/b978-0-444-63486-3.00013-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The extracellular matrix (ECM) occupies the space between both neurons and glial cells and thus provides a microenvironment that regulates multiple aspects of neural activities. Because of the vital role of ECM as a natural environment of cells in vivo, there is a growing interest to develop methodology allowing for the detailed structural and functional analyses of ECM. In this chapter, we provide the detailed overview of current microscopic methods used for ECM analysis and also describe general labeling strategies for ECM visualization. Since ECM remodeling involves the proteolytic cleavage of ECM, we will also describe current experimental approaches to image the proteolytic reorganization and/or degradation of ECM. The special focus of this chapter is set to the application of Förster resonance energy transfer-based approaches to monitor intracellular and extracellular matrix functions with high spatiotemporal resolution.
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Affiliation(s)
- Andre Zeug
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Michal Stawarski
- Laboratory of Cell Biophysics, Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Warsaw, Poland
| | | | - Svetlana Korotchenko
- Laboratory for Brain Extracellular Matrix Research, University of Nizhny Novgorod, Nizhny Novgorod, Russia; Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy; Department of Nanophysics, Istituto Italiano di Tecnologia, Genova, Italy
| | - Jakub Wlodarczyk
- Laboratory of Cell Biophysics, Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Alexander Dityatev
- Laboratory for Brain Extracellular Matrix Research, University of Nizhny Novgorod, Nizhny Novgorod, Russia; Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy; Department of Nanophysics, Istituto Italiano di Tecnologia, Genova, Italy; Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany
| | - Evgeni Ponimaskin
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany.
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43
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Mérola F, Fredj A, Betolngar DB, Ziegler C, Erard M, Pasquier H. Newly engineered cyan fluorescent proteins with enhanced performances for live cell FRET imaging. Biotechnol J 2013; 9:180-91. [DOI: 10.1002/biot.201300198] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Revised: 09/17/2013] [Accepted: 10/31/2013] [Indexed: 11/06/2022]
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Müller SM, Galliardt H, Schneider J, Barisas BG, Seidel T. Quantification of Förster resonance energy transfer by monitoring sensitized emission in living plant cells. FRONTIERS IN PLANT SCIENCE 2013; 4:413. [PMID: 24194740 PMCID: PMC3810607 DOI: 10.3389/fpls.2013.00413] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 09/29/2013] [Indexed: 05/20/2023]
Abstract
Förster resonance energy transfer (FRET) describes excitation energy exchange between two adjacent molecules typically in distances ranging from 2 to 10 nm. The process depends on dipole-dipole coupling of the molecules and its probability of occurrence cannot be proven directly. Mostly, fluorescence is employed for quantification as it represents a concurring process of relaxation of the excited singlet state S1 so that the probability of fluorescence decreases as the probability of FRET increases. This reflects closer proximity of the molecules or an orientation of donor and acceptor transition dipoles that facilitates FRET. Monitoring sensitized emission by 3-Filter-FRET allows for fast image acquisition and is suitable for quantifying FRET in dynamic systems such as living cells. In recent years, several calibration protocols were established to overcome to previous difficulties in measuring FRET-efficiencies. Thus, we can now obtain by 3-filter FRET FRET-efficiencies that are comparable to results from sophisticated fluorescence lifetime measurements. With the discovery of fluorescent proteins and their improvement toward spectral variants and usability in plant cells, the tool box for in vivo FRET-analyses in plant cells was provided and FRET became applicable for the in vivo detection of protein-protein interactions and for monitoring conformational dynamics. The latter opened the door toward a multitude of FRET-sensors such as the widely applied Ca(2+)-sensor Cameleon. Recently, FRET-couples of two fluorescent proteins were supplemented by additional fluorescent proteins toward FRET-cascades in order to monitor more complex arrangements. Novel FRET-couples involving switchable fluorescent proteins promise to increase the utility of FRET through combination with photoactivation-based super-resolution microscopy.
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Affiliation(s)
- Sara M. Müller
- Dynamic Cell Imaging, Faculty of Biology, Bielefeld UniversityBielefeld, Germany
| | - Helena Galliardt
- Dynamic Cell Imaging, Faculty of Biology, Bielefeld UniversityBielefeld, Germany
| | - Jessica Schneider
- Bioinformatic Resource Facility, Center for Biotechnology, Bielefeld UniversityBielefeld, Germany
| | - B. George Barisas
- Chemistry Department, Colorado State UniversityFort Collins, CO, USA
| | - Thorsten Seidel
- Dynamic Cell Imaging, Faculty of Biology, Bielefeld UniversityBielefeld, Germany
- *Correspondence: Thorsten Seidel, Dynamic Cell Imaging, Faculty of Biology, Bielefeld University, Universitätsstraße 25, 33501 Bielefeld, Germany e-mail:
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Leray A, Padilla-Parra S, Roul J, Héliot L, Tramier M. Spatio-Temporal Quantification of FRET in living cells by fast time-domain FLIM: a comparative study of non-fitting methods [corrected]. PLoS One 2013; 8:e69335. [PMID: 23874948 PMCID: PMC3715500 DOI: 10.1371/journal.pone.0069335] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 06/09/2013] [Indexed: 11/30/2022] Open
Abstract
Förster Resonance Energy Transfer (FRET) measured with Fluorescence Lifetime Imaging Microscopy (FLIM) is a powerful technique to investigate spatio-temporal regulation of protein-protein interactions in living cells. When using standard fitting methods to analyze time domain FLIM, the correct estimation of the FRET parameters requires a high number of photons and therefore long acquisition times which are incompatible with the observation of dynamic protein-protein interactions. Recently, non-fitting strategies have been developed for the analysis of FLIM images: the polar plot or "phasor" and the minimal fraction of interacting donor mfD . We propose here a novel non-fitting strategy based on the calculation of moments. We then compare the performance of these three methods when shortening the acquisition time: either by reducing the number of counted photons N or the number of temporal channels Nch , which is particularly adapted for the original fast-FLIM prototype presented in this work that employs the time gated approach. Based on theoretical calculations, Monte Carlo simulations and experimental data, we determine the domain of validity of each method. We thus demonstrate that the polar approach remains accurate for a large range of conditions (low N, Nch or small fractions of interacting donor fD ). The validity domain of the moments method is more restricted (not applicable when fD <0.25 or when Nch = 4) but it is more precise than the polar approach. We also demonstrate that the mfD is robust in all conditions and it is the most precise strategy; although it does not strictly provide the fraction of interacting donor. We show using the fast-FLIM prototype (with an acquisition rate up to 1 Hz) that these non-fitting strategies are very powerful for on-line analysis on a standard computer and thus for quantifying automatically the spatio-temporal activation of Rac-GTPase in living cells by FRET.
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Affiliation(s)
- Aymeric Leray
- Institut de Recherche Interdisciplinaire, USR 3078 CNRS, Université de Lille-Nord de France, Biophotonique Cellulaire Fonctionnelle, Villeneuve d'Ascq, France.
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A Sensitized Emission Based Calibration of FRET Efficiency for Probing the Architecture of Macromolecular Machines. Cell Mol Bioeng 2013; 6:369-382. [PMID: 24319499 PMCID: PMC3843746 DOI: 10.1007/s12195-013-0290-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 07/02/2013] [Indexed: 01/24/2023] Open
Abstract
Macromolecular machines participate in almost every cell biological function. These machines can take the form of well-defined protein structures such as the kinetochore, or more loosely organized protein assemblies like the endocytic coat. The protein architecture of these machines—the arrangement of multiple copies of protein subunits at the nanoscale, is necessary for understanding their cell biological function and biophysical mechanism. Defining this architecture in vivo presents a major challenge. High density of protein molecules within macromolecular machines severely limits the effectiveness of super-resolution microscopy. However, this density is ideal for Forster Resonance Energy Transfer (FRET), which can determine the proximity between neighboring molecules. Here, we present a simple FRET quantitation scheme that calibrates a standard epifluorescence microscope for measuring donor–acceptor separations. This calibration can be used to deduce FRET efficiency fluorescence intensity measurements. This method will allow accurate determination of FRET efficiency over a wide range of values and FRET pair number. It will also allow dynamic FRET measurements with high spatiotemporal resolution under cell biological conditions. Although the poor maturation efficiency of genetically encoded fluorescent proteins presents a challenge, we show that its effects can be alleviated. To demonstrate this methodology, we probe the in vivo architecture of the γ-Tubulin Ring. Our technique can be applied to study the architecture and dynamics of a wide range of macromolecular machines.
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Sun Y, Rombola C, Jyothikumar V, Periasamy A. Förster resonance energy transfer microscopy and spectroscopy for localizing protein-protein interactions in living cells. Cytometry A 2013; 83:780-93. [PMID: 23813736 DOI: 10.1002/cyto.a.22321] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 04/08/2013] [Accepted: 05/23/2013] [Indexed: 12/15/2022]
Abstract
The fundamental theory of Förster resonance energy transfer (FRET) was established in the 1940s. Its great power was only realized in the past 20 years after different techniques were developed and applied to biological experiments. This success was made possible by the availability of suitable fluorescent probes, advanced optics, detectors, microscopy instrumentation, and analytical tools. Combined with state-of-the-art microscopy and spectroscopy, FRET imaging allows scientists to study a variety of phenomena that produce changes in molecular proximity, thereby leading to many significant findings in the life sciences. In this review, we outline various FRET imaging techniques and their strengths and limitations; we also provide a biological model to demonstrate how to investigate protein-protein interactions in living cells using both intensity- and fluorescence lifetime-based FRET microscopy methods.
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Affiliation(s)
- Yuansheng Sun
- The W.M. Keck Center for Cellular Imaging (KCCI), Department of Biology, Physical and Life Sciences Building, University of Virginia, Charlottesville, Virginia
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Zeug A, Woehler A, Neher E, Ponimaskin EG. Quantitative intensity-based FRET approaches--a comparative snapshot. Biophys J 2013. [PMID: 23199910 DOI: 10.1016/j.bpj.2012.09.031] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Förster resonance energy transfer (FRET) has become an important tool for analyzing different aspects of interactions among biological macromolecules in their native environments. FRET analysis has also been successfully applied to study the spatiotemporal regulation of various cellular processes using genetically encoded FRET-based biosensors. A variety of procedures have been described for measuring FRET efficiency or the relative abundance of donor-acceptor complexes, based on analysis of the donor fluorescence lifetime or the spectrally resolved fluorescence intensity. The latter methods are preferable if one wants to not only quantify the apparent FRET efficiencies but also calculate donor-acceptor stoichiometry and observe fast dynamic changes in the interactions among donor and acceptor molecules in live cells. This review focuses on a comparison of the available intensity-based approaches used to measure FRET. We discuss their strengths and weaknesses in terms of FRET quantification, and provide several examples of biological applications.
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Affiliation(s)
- André Zeug
- Cellular Neurophysiology, Center of Physiology, Hannover Medical School, Hannover, Germany
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Stender AS, Marchuk K, Liu C, Sander S, Meyer MW, Smith EA, Neupane B, Wang G, Li J, Cheng JX, Huang B, Fang N. Single cell optical imaging and spectroscopy. Chem Rev 2013; 113:2469-527. [PMID: 23410134 PMCID: PMC3624028 DOI: 10.1021/cr300336e] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Anthony S. Stender
- Department of Chemistry, Iowa State University and Ames Laboratory, U. S. Department of Energy, Ames, IA 50011, USA
| | - Kyle Marchuk
- Department of Chemistry, Iowa State University and Ames Laboratory, U. S. Department of Energy, Ames, IA 50011, USA
| | - Chang Liu
- Department of Chemistry, Iowa State University and Ames Laboratory, U. S. Department of Energy, Ames, IA 50011, USA
| | - Suzanne Sander
- Department of Chemistry, Iowa State University and Ames Laboratory, U. S. Department of Energy, Ames, IA 50011, USA
| | - Matthew W. Meyer
- Department of Chemistry, Iowa State University and Ames Laboratory, U. S. Department of Energy, Ames, IA 50011, USA
| | - Emily A. Smith
- Department of Chemistry, Iowa State University and Ames Laboratory, U. S. Department of Energy, Ames, IA 50011, USA
| | - Bhanu Neupane
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Gufeng Wang
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Junjie Li
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907
| | - Ji-Xin Cheng
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907
| | - Bo Huang
- Department of Pharmaceutical Chemistry and Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158
| | - Ning Fang
- Department of Chemistry, Iowa State University and Ames Laboratory, U. S. Department of Energy, Ames, IA 50011, USA
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Single-stranded nucleic acids promote SAMHD1 complex formation. J Mol Med (Berl) 2013; 91:759-70. [PMID: 23371319 DOI: 10.1007/s00109-013-0995-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 12/03/2012] [Accepted: 01/02/2013] [Indexed: 10/27/2022]
Abstract
SAM domain and HD domain-containing protein 1 (SAMHD1) is a dGTP-dependent triphosphohydrolase that degrades deoxyribonucleoside triphosphates (dNTPs) thereby limiting the intracellular dNTP pool. Mutations in SAMHD1 cause Aicardi-Goutières syndrome (AGS), an inflammatory encephalopathy that mimics congenital viral infection and that phenotypically overlaps with the autoimmune disease systemic lupus erythematosus. Both disorders are characterized by activation of the antiviral cytokine interferon-α initiated by immune recognition of self nucleic acids. Here we provide first direct evidence that SAMHD1 associates with endogenous nucleic acids in situ. Using fluorescence cross-correlation spectroscopy, we demonstrate that SAMHD1 specifically interacts with ssRNA and ssDNA and establish that nucleic acid-binding and formation of SAMHD1 complexes are mutually dependent. Interaction with nucleic acids and complex formation do not require the SAM domain, but are dependent on the HD domain and the C-terminal region of SAMHD1. We finally demonstrate that mutations associated with AGS exhibit both impaired nucleic acid-binding and complex formation implicating that interaction with nucleic acids is an integral aspect of SAMHD1 function.
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