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  1. Article ; Online: Particle-based phasor-FLIM-FRET resolves protein-protein interactions inside single viral particles.

    Coucke, Quinten / Parveen, Nagma / Fernández, Guillermo Solís / Qian, Chen / Hofkens, Johan / Debyser, Zeger / Hendrix, Jelle

    Biophysical reports

    2023  Volume 3, Issue 3, Page(s) 100122

    Abstract: Fluorescence lifetime imaging microscopy (FLIM) is a popular modality to create additional contrast in fluorescence images. By carefully analyzing pixel-based nanosecond lifetime patterns, FLIM allows studying complex molecular populations. At the single- ...

    Abstract Fluorescence lifetime imaging microscopy (FLIM) is a popular modality to create additional contrast in fluorescence images. By carefully analyzing pixel-based nanosecond lifetime patterns, FLIM allows studying complex molecular populations. At the single-molecule or single-particle level, however, image series often suffer from low signal intensities per pixel, rendering it difficult to quantitatively disentangle different lifetime species, such as during Förster resonance energy transfer (FRET) analysis in the presence of a significant donor-only fraction. In this article we investigate whether an object localization strategy and the phasor approach to FLIM have beneficial effects when carrying out FRET analyses of single particles. Using simulations, we first showed that an average of ∼300 photons, spread over the different pixels encompassing single fluorescing particles and without background, is enough to determine a correct phasor signature (SD < 5% for a 4-ns lifetime). For immobilized single- or double-labeled dsDNA molecules, we next validated that particle-based phasor-FLIM-FRET readily allows estimating fluorescence lifetimes and FRET from single molecules. Thirdly, we applied particle-based phasor-FLIM-FRET to investigate protein-protein interactions in subdiffraction HIV-1 viral particles. To do this, we first quantitatively compared the fluorescence brightness, lifetime, and photostability of different popular fluorescent protein-based FRET probes when genetically fused to the HIV-1 integrase enzyme in viral particles, and conclude that eGFP, mTurquoise2, and mScarlet perform best. Finally, for viral particles coexpressing FRET-donor/acceptor-labeled IN, we determined the absolute FRET efficiency of IN oligomers. Available in a convenient open-source graphical user interface, we believe that particle-based phasor-FLIM-FRET is a promising tool to provide detailed insights in samples suffering from low overall signal intensities.
    Language English
    Publishing date 2023-08-09
    Publishing country United States
    Document type Journal Article
    ISSN 2667-0747
    ISSN (online) 2667-0747
    DOI 10.1016/j.bpr.2023.100122
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Synthetic fibrous hydrogels as a platform to decipher cell-matrix mechanical interactions.

    Yuan, Hongbo / Liu, Kaizheng / Cóndor, Mar / Barrasa-Fano, Jorge / Louis, Boris / Vandaele, Johannes / de Almeida, Paula / Coucke, Quinten / Chen, Wen / Oosterwijk, Egbert / Xing, Chengfen / Van Oosterwyck, Hans / Kouwer, Paul H J / Rocha, Susana

    Proceedings of the National Academy of Sciences of the United States of America

    2023  Volume 120, Issue 15, Page(s) e2216934120

    Abstract: Cells continuously sense external forces from their microenvironment, the extracellular matrix (ECM). In turn, they generate contractile forces, which stiffen and remodel this matrix. Although this bidirectional mechanical exchange is crucial for many ... ...

    Abstract Cells continuously sense external forces from their microenvironment, the extracellular matrix (ECM). In turn, they generate contractile forces, which stiffen and remodel this matrix. Although this bidirectional mechanical exchange is crucial for many cell functions, it remains poorly understood. Key challenges are that the majority of available matrices for such studies, either natural or synthetic, are difficult to control or lack biological relevance. Here, we use a synthetic, yet highly biomimetic hydrogel based on polyisocyanide (PIC) polymers to investigate the effects of the fibrous architecture and the nonlinear mechanics on cell-matrix interactions. Live-cell rheology was combined with advanced microscopy-based approaches to understand the mechanisms behind cell-induced matrix stiffening and plastic remodeling. We demonstrate how cell-mediated fiber remodeling and the propagation of fiber displacements are modulated by adjusting the biological and mechanical properties of this material. Moreover, we validate the biological relevance of our results by demonstrating that cellular tractions in PIC gels develop analogously to those in the natural ECM. This study highlights the potential of PIC gels to disentangle complex bidirectional cell-matrix interactions and to improve the design of materials for mechanobiology studies.
    MeSH term(s) Hydrogels ; Extracellular Matrix/physiology ; Cell Communication
    Chemical Substances Hydrogels
    Language English
    Publishing date 2023-04-03
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2216934120
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Quantification of FRET-induced angular displacement by monitoring sensitized acceptor anisotropy using a dim fluorescent donor.

    Laskaratou, Danai / Fernández, Guillermo Solís / Coucke, Quinten / Fron, Eduard / Rocha, Susana / Hofkens, Johan / Hendrix, Jelle / Mizuno, Hideaki

    Nature communications

    2021  Volume 12, Issue 1, Page(s) 2541

    Abstract: Förster resonance energy transfer (FRET) between fluorescent proteins has become a common platform for designing genetically encoded biosensors. For live cell imaging, the acceptor-to-donor intensity ratio is most commonly used to readout FRET efficiency, ...

    Abstract Förster resonance energy transfer (FRET) between fluorescent proteins has become a common platform for designing genetically encoded biosensors. For live cell imaging, the acceptor-to-donor intensity ratio is most commonly used to readout FRET efficiency, which largely depends on the proximity between donor and acceptor. Here, we introduce an anisotropy-based mode of FRET detection (FADED: FRET-induced Angular Displacement Evaluation via Dim donor), which probes for relative orientation rather than proximity alteration. A key element in this technique is suppression of donor bleed-through, which allows measuring purer sensitized acceptor anisotropy. This is achieved by developing Geuda Sapphire, a low-quantum-yield FRET-competent fluorescent protein donor. As a proof of principle, Ca
    MeSH term(s) Anisotropy ; Bacterial Proteins/metabolism ; Biosensing Techniques ; Escherichia coli/genetics ; Escherichia coli/metabolism ; Fluorescence Resonance Energy Transfer/methods ; HeLa Cells ; Humans ; Optical Imaging/methods
    Chemical Substances Bacterial Proteins
    Language English
    Publishing date 2021-05-05
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2553671-0
    ISSN 2041-1723 ; 2041-1723
    ISSN (online) 2041-1723
    ISSN 2041-1723
    DOI 10.1038/s41467-021-22816-7
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Sub-millisecond conformational dynamics of the A

    Maslov, Ivan / Volkov, Oleksandr / Khorn, Polina / Orekhov, Philipp / Gusach, Anastasiia / Kuzmichev, Pavel / Gerasimov, Andrey / Luginina, Aleksandra / Coucke, Quinten / Bogorodskiy, Andrey / Gordeliy, Valentin / Wanninger, Simon / Barth, Anders / Mishin, Alexey / Hofkens, Johan / Cherezov, Vadim / Gensch, Thomas / Hendrix, Jelle / Borshchevskiy, Valentin

    Communications biology

    2023  Volume 6, Issue 1, Page(s) 362

    Abstract: The complex pharmacology of G-protein-coupled receptors (GPCRs) is defined by their multi-state conformational dynamics. Single-molecule Förster Resonance Energy Transfer (smFRET) is well suited to quantify dynamics for individual protein molecules; ... ...

    Abstract The complex pharmacology of G-protein-coupled receptors (GPCRs) is defined by their multi-state conformational dynamics. Single-molecule Förster Resonance Energy Transfer (smFRET) is well suited to quantify dynamics for individual protein molecules; however, its application to GPCRs is challenging. Therefore, smFRET has been limited to studies of inter-receptor interactions in cellular membranes and receptors in detergent environments. Here, we performed smFRET experiments on functionally active human A
    MeSH term(s) Humans ; Fluorescence Resonance Energy Transfer ; Receptor, Adenosine A2A/metabolism ; Molecular Conformation ; Cell Membrane/metabolism ; Proteins/metabolism
    Chemical Substances Receptor, Adenosine A2A ; Proteins
    Language English
    Publishing date 2023-04-03
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 2399-3642
    ISSN (online) 2399-3642
    DOI 10.1038/s42003-023-04727-z
    Database MEDical Literature Analysis and Retrieval System OnLINE

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