1
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Chatterjee S, Kramer SN, Wellnitz B, Kim A, Kisley L. Spatially Resolving Size Effects on Diffusivity in Nanoporous Extracellular Matrix-like Materials with Fluorescence Correlation Spectroscopy Super-Resolution Optical Fluctuation Imaging. J Phys Chem B 2023; 127:4430-4440. [PMID: 37167609 PMCID: PMC10303168 DOI: 10.1021/acs.jpcb.3c00941] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
It is well documented that the nanoscale structures within porous microenvironments greatly impact the diffusion dynamics of molecules. However, how the interaction between the environment and molecules influences the diffusion dynamics has not been thoroughly explored. Here, we show that fluorescence correlation spectroscopy super-resolution optical fluctuation imaging (fcsSOFI) can be used to accurately measure the diffusion dynamics of molecules within varying matrices such as nanopatterned surfaces and porous agarose hydrogels. Our data demonstrate the robustness of fcsSOFI, where it is possible not only to quantify the diffusion speeds of molecules in heterogeneous media but also to recover the matrix structure with resolution on the order of 100 nm. Using dextran molecules of varying sizes, we show that the diffusion coefficient is sensitive to the change in the molecular hydrodynamic radius. fcsSOFI images further reveal that smaller dextran molecules can freely move through the small pores of the hydrogel and report the detailed porous structure and local diffusion heterogeneities not captured by the average diffusion coefficient. Conversely, bigger dextran molecules are confined and unable to freely move through the hydrogel, highlighting only the larger pore structures. These findings establish fcsSOFI as a powerful tool to characterize spatial and diffusion information of diverse macromolecules within biorelevant matrices.
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Affiliation(s)
- Surajit Chatterjee
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079, United States
| | - Stephanie N Kramer
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079, United States
| | - Benjamin Wellnitz
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079, United States
| | - Albert Kim
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079, United States
| | - Lydia Kisley
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079, United States
- Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106-7079, United States
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2
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Perez Schmidt P, Luedtke T, Moretti P, Di Gianvincenzo P, Fernandez Leyes M, Espuche B, Amenitsch H, Wang G, Ritacco H, Polito L, Ortore MG, Moya SE. Assembly and recognition mechanisms of glycosylated PEGylated polyallylamine phosphate nanoparticles: A fluorescence correlation spectroscopy and small angle X-ray scattering study. J Colloid Interface Sci 2023; 645:448-457. [PMID: 37156153 DOI: 10.1016/j.jcis.2023.04.136] [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: 02/28/2023] [Revised: 04/18/2023] [Accepted: 04/25/2023] [Indexed: 05/10/2023]
Abstract
HYPOTHESIS Modification of polyallylamine hydrochloride (PAH) with heterobifunctional low molecular weight polyethylene glycol (PEG) (600 and 1395 Da), and subsequent attachment of mannose, glucose, or lactose sugars to PEG, can lead to formation of polyamine phosphate nanoparticles (PANs) with lectin binding affinity and narrow size distribution. EXPERIMENTS Size, polydispersity, and internal structure of glycosylated PEGylated PANs were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and small angle X-ray scattering (SAXS). Fluorescence correlation spectroscopy (FCS) was used to study the association of labelled glycol-PEGylated PANs. The number of polymer chains forming the nanoparticles was determined from the changes in amplitude of the cross-correlation function of the polymers after formation of the nanoparticles. SAXS and fluorescence cross-correlation spectroscopy were used to investigate the interaction of PANs with lectins: concanavalin A with mannose modified PANs, and jacalin with lactose modified ones. FINDINGS Glyco-PEGylated PANs are highly monodispersed, with diameters of a few tens of nanometers and low charge, and a structure corresponding to spheres with Gaussian chains. FCS shows that the PANs are single chain nanoparticles or formed by two polymer chains. Concanavalin A and jacalin show specific interactions for the glyco-PEGylated PANs with higher affinity than bovine serum albumin.
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Affiliation(s)
- Patricia Perez Schmidt
- Soft Matter Nanotechnology Group, CIC biomaGUNE, Basque Research and Technology Alliance (BRTA), Paseo Miramón 182, 20014 Donostia-San Sebastián, Guipúzcoa, Spain; CNR - ISTM, Nanotechnology Lab., Via G. Fantoli 16/15, Milan, Italy
| | - Tanja Luedtke
- Soft Matter Nanotechnology Group, CIC biomaGUNE, Basque Research and Technology Alliance (BRTA), Paseo Miramón 182, 20014 Donostia-San Sebastián, Guipúzcoa, Spain
| | - Paolo Moretti
- Department of Life and Environmental Science, Marche Polytechnic University, via Brecce bianche, I-60131 Ancona, Italy
| | - Paolo Di Gianvincenzo
- Soft Matter Nanotechnology Group, CIC biomaGUNE, Basque Research and Technology Alliance (BRTA), Paseo Miramón 182, 20014 Donostia-San Sebastián, Guipúzcoa, Spain
| | - Marcos Fernandez Leyes
- IFISUR Instituto de Física del Sur (IFISUR-CONICET), Av. Alem 1253, Bahía Blanca 8000, Argentina
| | - Bruno Espuche
- POLYMAT, Applied Chemistry Department, Faculty of Chemistry, University of the Basque Country, UPV/EHU, Paseo Manuel de Lardizabal 3, 20018 Donostia-San Sebastián, Guipúzcoa, Spain
| | - Heinz Amenitsch
- Institute of Inorganic Chemistry, Graz University of Technology, Austria
| | - Guocheng Wang
- Research Center for Human Tissues and Organs Degeneration Shenzhen Institute of Advanced Technology Chinese Academy of Science Shenzhen, Guangdong 518055, China
| | - Hernan Ritacco
- IFISUR Instituto de Física del Sur (IFISUR-CONICET), Av. Alem 1253, Bahía Blanca 8000, Argentina
| | - Laura Polito
- CNR - ISTM, Nanotechnology Lab., Via G. Fantoli 16/15, Milan, Italy
| | - M Grazia Ortore
- Department of Life and Environmental Science, Marche Polytechnic University, via Brecce bianche, I-60131 Ancona, Italy.
| | - S E Moya
- Soft Matter Nanotechnology Group, CIC biomaGUNE, Basque Research and Technology Alliance (BRTA), Paseo Miramón 182, 20014 Donostia-San Sebastián, Guipúzcoa, Spain.
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3
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Mørch AM, Schneider F. Investigating Diffusion Dynamics and Interactions with Scanning Fluorescence Correlation Spectroscopy (sFCS). Methods Mol Biol 2023; 2654:61-89. [PMID: 37106176 DOI: 10.1007/978-1-0716-3135-5_5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Activation of immune cells and formation of immunological synapses (IS) rely critically on the reorganization of the plasma membrane. These highly orchestrated processes are driven by diffusion and oligomerization dynamics, as well as by single molecule interactions. While slow macro- and meso-scale changes in organization can be observed with conventional imaging, fast nano-scale dynamics are often missed with traditional approaches, but resolving them is, nonetheless, essential to understand the underlying biological mechanisms at play. Here, we describe the use of scanning fluorescence correlation spectroscopy (sFCS) and scanning fluorescence cross-correlation spectroscopy (sFCCS) to study reorganization and changes in molecular diffusion dynamics and interactions during IS formation and in other biological settings. We focus on the practical aspects of the measurements including calibration and alignment of the optical setup, present a comprehensive protocol to perform the measurements, and provide data analysis pipelines and strategies. Finally, we show an exemplary application of the technology to studying Lck diffusion during T-cell signaling.
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Affiliation(s)
| | - Falk Schneider
- Translational Imaging Center, University of Southern California, Los Angeles, California, USA.
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4
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Ambrosi G, Voloshanenko O, Eckert AF, Kranz D, Nienhaus GU, Boutros M. Allele-specific endogenous tagging and quantitative analysis of β-catenin in colorectal cancer cells. eLife 2022; 11:64498. [PMID: 35014953 PMCID: PMC8752093 DOI: 10.7554/elife.64498] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/16/2021] [Indexed: 12/16/2022] Open
Abstract
Wnt signaling plays important roles in development, homeostasis, and tumorigenesis. Mutations in β-catenin that activate Wnt signaling have been found in colorectal and hepatocellular carcinomas. However, the dynamics of wild-type and mutant forms of β-catenin are not fully understood. Here, we genome-engineered fluorescently tagged alleles of endogenous β-catenin in a colorectal cancer cell line. Wild-type and oncogenic mutant alleles were tagged with different fluorescent proteins, enabling the analysis of both variants in the same cell. We analyzed the properties of both β-catenin alleles using immunoprecipitation, immunofluorescence, and fluorescence correlation spectroscopy approaches, revealing distinctly different biophysical properties. In addition, activation of Wnt signaling by treatment with a GSK3β inhibitor or a truncating APC mutation modulated the wild-type allele to mimic the properties of the mutant β-catenin allele. The one-step tagging strategy demonstrates how genome engineering can be employed for the parallel functional analysis of different genetic variants.
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Affiliation(s)
- Giulia Ambrosi
- German Cancer Research Center (DKFZ), Division of Signaling and Functional Genomics and Heidelberg University, BioQuant and Medical Faculty Mannheim, Heidelberg, Germany
| | - Oksana Voloshanenko
- German Cancer Research Center (DKFZ), Division of Signaling and Functional Genomics and Heidelberg University, BioQuant and Medical Faculty Mannheim, Heidelberg, Germany
| | - Antonia F Eckert
- Institute of Applied Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Dominique Kranz
- German Cancer Research Center (DKFZ), Division of Signaling and Functional Genomics and Heidelberg University, BioQuant and Medical Faculty Mannheim, Heidelberg, Germany
| | - G Ulrich Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Michael Boutros
- German Cancer Research Center (DKFZ), Division of Signaling and Functional Genomics and Heidelberg University, BioQuant and Medical Faculty Mannheim, Heidelberg, Germany
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5
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Gao P, Nienhaus GU. Axial line-scanning stimulated emission depletion fluorescence correlation spectroscopy. OPTICS LETTERS 2021; 46:2184-2187. [PMID: 33929450 DOI: 10.1364/ol.420765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 04/01/2021] [Indexed: 06/12/2023]
Abstract
Investigating the dynamics and interactions of biomolecules within or attached to membranes of living cells is crucial for understanding biology at the molecular level. In this pursuit, classical, diffraction-limited optical fluorescence microscopy is widely used, but it faces limitations due to (1) the heterogeneity of biomembranes on the nanoscale and (2) the intrinsic motion of membranes with respect to the focus. Here we introduce a new confocal microscopy-based fluctuation spectroscopy technique aimed at alleviating these two problems, called axial line-scanning stimulated emission depletion fluorescence correlation spectroscopy (axial ls-STED-FCS). Axial line scanning by means of a tunable acoustic gradient index of refraction lens provides a time resolution of a few microseconds, which is more than two orders of magnitude greater than that of conventional, lateral line-scanning fluorescence correlation spectroscopy (typically around 1 ms). Using STED excitation, the observation area on the membrane can be reduced 10-100 fold, resulting in sub-diffraction spatial resolution and the ability to study samples with densely labeled membranes. Due to these attractive properties, we expect that the axial ls-STED-FCS will find wide application, especially in the biomolecular sciences.
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6
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Schneider F, Colin-York H, Fritzsche M. Quantitative Bio-Imaging Tools to Dissect the Interplay of Membrane and Cytoskeletal Actin Dynamics in Immune Cells. Front Immunol 2021; 11:612542. [PMID: 33505401 PMCID: PMC7829180 DOI: 10.3389/fimmu.2020.612542] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 11/23/2020] [Indexed: 12/13/2022] Open
Abstract
Cellular function is reliant on the dynamic interplay between the plasma membrane and the actin cytoskeleton. This critical relationship is of particular importance in immune cells, where both the cytoskeleton and the plasma membrane work in concert to organize and potentiate immune signaling events. Despite their importance, there remains a critical gap in understanding how these respective dynamics are coupled, and how this coupling in turn may influence immune cell function from the bottom up. In this review, we highlight recent optical technologies that could provide strategies to investigate the simultaneous dynamics of both the cytoskeleton and membrane as well as their interplay, focusing on current and future applications in immune cells. We provide a guide of the spatio-temporal scale of each technique as well as highlighting novel probes and labels that have the potential to provide insights into membrane and cytoskeletal dynamics. The quantitative biophysical tools presented here provide a new and exciting route to uncover the relationship between plasma membrane and cytoskeletal dynamics that underlies immune cell function.
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Affiliation(s)
- Falk Schneider
- Medical Research Council (MRC) Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Huw Colin-York
- Medical Research Council (MRC) Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
- Kennedy Institute for Rheumatology, University of Oxford, Oxford, United Kingdom
| | - Marco Fritzsche
- Medical Research Council (MRC) Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
- Kennedy Institute for Rheumatology, University of Oxford, Oxford, United Kingdom
- Rosalind Franklin Institute, Harwell Campus, Didcot, United Kingdom
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7
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Dawes ML, Soeller C, Scholpp S. Studying molecular interactions in the intact organism: fluorescence correlation spectroscopy in the living zebrafish embryo. Histochem Cell Biol 2020; 154:507-519. [PMID: 33067656 PMCID: PMC7609432 DOI: 10.1007/s00418-020-01930-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2020] [Indexed: 02/07/2023]
Abstract
Cell behaviour and function is determined through the interactions of a multitude of molecules working in concert. To observe these molecular dynamics, biophysical studies have been developed that track single interactions. Fluorescence correlation spectroscopy (FCS) is an optical biophysical technique that non-invasively resolves single molecules through recording the signal intensity at the femtolitre scale. However, recording the behaviour of these biomolecules using in vitro-based assays often fails to recapitulate the full range of variables in vivo that directly confer dynamics. Therefore, there has been an increasing interest in observing the state of these biomolecules within living organisms such as the zebrafish Danio rerio. In this review, we explore the advancements of FCS within the zebrafish and compare and contrast these findings to those found in vitro.
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Affiliation(s)
- Michael L Dawes
- Living Systems Institute, School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4QD, UK
| | - Christian Soeller
- Living Systems Institute, College of Engineering, Mathematics, and Physical Sciences, University of Exeter, Exeter, EX4 4QD, UK
| | - Steffen Scholpp
- Living Systems Institute, School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4QD, UK.
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8
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Tzoneva R, Stoyanova T, Petrich A, Popova D, Uzunova V, Momchilova A, Chiantia S. Effect of Erufosine on Membrane Lipid Order in Breast Cancer Cell Models. Biomolecules 2020; 10:E802. [PMID: 32455962 PMCID: PMC7277205 DOI: 10.3390/biom10050802] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 05/15/2020] [Accepted: 05/19/2020] [Indexed: 12/11/2022] Open
Abstract
Alkylphospholipids are a novel class of antineoplastic drugs showing remarkable therapeutic potential. Among them, erufosine (EPC3) is a promising drug for the treatment of several types of tumors. While EPC3 is supposed to exert its function by interacting with lipid membranes, the exact molecular mechanisms involved are not known yet. In this work, we applied a combination of several fluorescence microscopy and analytical chemistry approaches (i.e., scanning fluorescence correlation spectroscopy, line-scan fluorescence correlation spectroscopy, generalized polarization imaging, as well as thin layer and gas chromatography) to quantify the effect of EPC3 in biophysical models of the plasma membrane, as well as in cancer cell lines. Our results indicate that EPC3 affects lipid-lipid interactions in cellular membranes by decreasing lipid packing and increasing membrane disorder and fluidity. As a consequence of these alterations in the lateral organization of lipid bilayers, the diffusive dynamics of membrane proteins are also significantly increased. Taken together, these findings suggest that the mechanism of action of EPC3 could be linked to its effects on fundamental biophysical properties of lipid membranes, as well as on lipid metabolism in cancer cells.
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Affiliation(s)
- Rumiana Tzoneva
- Bulgarian Academy of Sciences, Institute of Biophysics and Biomedical Engineering, 1113 Sofia, Bulgaria; (R.T.); (T.S.); (D.P.); (V.U.); (A.M.)
| | - Tihomira Stoyanova
- Bulgarian Academy of Sciences, Institute of Biophysics and Biomedical Engineering, 1113 Sofia, Bulgaria; (R.T.); (T.S.); (D.P.); (V.U.); (A.M.)
| | - Annett Petrich
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Street 24-25, 14476 Potsdam, Germany;
| | - Desislava Popova
- Bulgarian Academy of Sciences, Institute of Biophysics and Biomedical Engineering, 1113 Sofia, Bulgaria; (R.T.); (T.S.); (D.P.); (V.U.); (A.M.)
| | - Veselina Uzunova
- Bulgarian Academy of Sciences, Institute of Biophysics and Biomedical Engineering, 1113 Sofia, Bulgaria; (R.T.); (T.S.); (D.P.); (V.U.); (A.M.)
| | - Albena Momchilova
- Bulgarian Academy of Sciences, Institute of Biophysics and Biomedical Engineering, 1113 Sofia, Bulgaria; (R.T.); (T.S.); (D.P.); (V.U.); (A.M.)
| | - Salvatore Chiantia
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Street 24-25, 14476 Potsdam, Germany;
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9
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Eckert AF, Gao P, Wesslowski J, Wang X, Rath J, Nienhaus K, Davidson G, Nienhaus GU. Measuring ligand-cell surface receptor affinities with axial line-scanning fluorescence correlation spectroscopy. eLife 2020; 9:55286. [PMID: 32441251 PMCID: PMC7289602 DOI: 10.7554/elife.55286] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 05/21/2020] [Indexed: 12/12/2022] Open
Abstract
Development and homeostasis of multicellular organisms is largely controlled by complex cell-cell signaling networks that rely on specific binding of secreted ligands to cell surface receptors. The Wnt signaling network, as an example, involves multiple ligands and receptors to elicit specific cellular responses. To understand the mechanisms of such a network, ligand-receptor interactions should be characterized quantitatively, ideally in live cells or tissues. Such measurements are possible using fluorescence microscopy yet challenging due to sample movement, low signal-to-background ratio and photobleaching. Here, we present a robust approach based on fluorescence correlation spectroscopy with ultra-high speed axial line scanning, yielding precise equilibrium dissociation coefficients of interactions in the Wnt signaling pathway. Using CRISPR/Cas9 editing to endogenously tag receptors with fluorescent proteins, we demonstrate that the method delivers precise results even with low, near-native amounts of receptors.
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Affiliation(s)
| | - Peng Gao
- Institute of Applied Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Janine Wesslowski
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Xianxian Wang
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Jasmijn Rath
- Institute of Applied Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Karin Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Gary Davidson
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Gerd Ulrich Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States
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10
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Lee HM, Kwon SB, Son A, Kim DH, Kim KH, Lim J, Kwon YG, Kang JS, Lee BK, Byun YH, Seong BL. Stabilization of Intrinsically Disordered DKK2 Protein by Fusion to RNA-Binding Domain. Int J Mol Sci 2019; 20:ijms20112847. [PMID: 31212691 PMCID: PMC6600415 DOI: 10.3390/ijms20112847] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/11/2019] [Accepted: 06/10/2019] [Indexed: 12/26/2022] Open
Abstract
Intrinsic disorders are a common feature of hub proteins in eukaryotic interactomes controlling the signaling pathways. The intrinsically disordered proteins (IDPs) are prone to misfolding, and maintaining their functional stability remains a major challenge in validating their therapeutic potentials. Considering that IDPs are highly enriched in RNA-binding proteins (RBPs), here we reasoned and confirmed that IDPs could be stabilized by fusion to RBPs. Dickkopf2 (DKK2), Wnt antagonist and a prototype IDP, was fused with lysyl-tRNA synthetase (LysRS), with or without the fragment crystallizable (Fc) domain of an immunoglobulin and expressed predominantly as a soluble form from a bacterial host. The functional competence was confirmed by in vitro Wnt signaling reporter and tube formation in human umbilical vein endothelial cells (HUVECs) and in vivo Matrigel plug assay. The removal of LysRS by site-specific protease cleavage prompted the insoluble aggregation, confirming that the linkage to RBP chaperones the functional competence of IDPs. While addressing to DKK2 as a key modulator for cancer and ischemic vascular diseases, our results suggest the use of RBPs as stabilizers of disordered proteinaceous materials for acquiring and maintaining the structural stability and functional competence, which would impact the druggability of a variety of IDPs from human proteome.
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Affiliation(s)
- Hye Min Lee
- Department of Biotechnology, College of Life Sciences and Biotechnology, Yonsei University, Seoul 03722, Korea.
- Vaccine Translational Research Center, Yonsei University, Seoul 03722, Korea.
| | - Soon Bin Kwon
- Department of Biotechnology, College of Life Sciences and Biotechnology, Yonsei University, Seoul 03722, Korea.
- Vaccine Translational Research Center, Yonsei University, Seoul 03722, Korea.
| | - Ahyun Son
- Department of Biotechnology, College of Life Sciences and Biotechnology, Yonsei University, Seoul 03722, Korea.
- Vaccine Translational Research Center, Yonsei University, Seoul 03722, Korea.
| | - Doo Hyun Kim
- Department of Pharmacology, and Center for Cancer Research and Diagnostic Medicine, IBST, School of Medicine, Konkuk University, Seoul 05030, Korea.
| | - Kyun-Hwan Kim
- Department of Pharmacology, and Center for Cancer Research and Diagnostic Medicine, IBST, School of Medicine, Konkuk University, Seoul 05030, Korea.
| | - Jonghyo Lim
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea.
| | - Young-Guen Kwon
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea.
| | - Jin Sun Kang
- ProCell R&D Institute, ProCell Therapeutics, Inc., Ace-Twin Tower II, Guro3-dong, Guro-gu, Seoul 08381, Korea.
| | - Byung Kyu Lee
- ProCell R&D Institute, ProCell Therapeutics, Inc., Ace-Twin Tower II, Guro3-dong, Guro-gu, Seoul 08381, Korea.
| | - Young Ho Byun
- Department of Biotechnology, College of Life Sciences and Biotechnology, Yonsei University, Seoul 03722, Korea.
- Vaccine Translational Research Center, Yonsei University, Seoul 03722, Korea.
| | - Baik L Seong
- Department of Biotechnology, College of Life Sciences and Biotechnology, Yonsei University, Seoul 03722, Korea.
- Vaccine Translational Research Center, Yonsei University, Seoul 03722, Korea.
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11
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Gao X, Gao P, Prunsche B, Nienhaus K, Nienhaus GU. Pulsed interleaved excitation-based line-scanning spatial correlation spectroscopy (PIE-lsSCS). Sci Rep 2018; 8:16722. [PMID: 30425308 PMCID: PMC6233157 DOI: 10.1038/s41598-018-35146-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 10/31/2018] [Indexed: 11/09/2022] Open
Abstract
We report pulsed interleaved excitation (PIE) based line-scanning spatial correlation spectroscopy (PIE-lsSCS), a quantitative fluorescence microscopy method for the study of dynamics in free-standing lipid bilayer membranes. Using a confocal microscope, we scan multiple lines perpendicularly through the membrane, each one laterally displaced from the previous one by several ten nanometers. Scanning through the membrane enables us to eliminate intensity fluctuations due to membrane displacements with respect to the observation volume. The diffusion of fluorescent molecules within the membrane is quantified by spatial correlation analysis, based on the fixed lag times between successive line scans. PIE affords dual-color excitation within a single line scan and avoids channel crosstalk. PIE-lsSCS data are acquired from a larger membrane region so that sampling is more efficient. Moreover, the local photon flux is reduced compared with single-point experiments, resulting in a smaller fraction of photobleached molecules for identical exposure times. This is helpful for precise measurements on live cells and tissues. We have evaluated the method with experiments on fluorescently labeled giant unilamellar vesicles (GUVs) and membrane-stained live cells.
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Affiliation(s)
- Xiang Gao
- Institute of Applied Physics, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany
| | - Peng Gao
- Institute of Applied Physics, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany
| | - Benedikt Prunsche
- Institute of Applied Physics, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany
| | - Karin Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany
| | - Gerd Ulrich Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany.
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany.
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany.
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA.
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12
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Unsay JD, Murad F, Hermann E, Ries J, García-Sáez AJ. Scanning Fluorescence Correlation Spectroscopy for Quantification of the Dynamics and Interactions in Tube Organelles of Living Cells. Chemphyschem 2018; 19:3273-3278. [PMID: 30335213 DOI: 10.1002/cphc.201800705] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Indexed: 01/03/2023]
Abstract
Single-molecule spectroscopic quantification of protein-protein interactions directly in the organelles of living cells is highly desirable but remains challenging. Bulk methods, such as Förster resonance energy transfer (FRET), currently only give a relative quantification of the strength of protein-protein interactions. Here, we introduce tube scanning fluorescence cross-correlation spectroscopy (tubeSFCCS) for the absolute quantification of diffusion and complex formation of fluorescently labeled molecules in the mitochondrial compartments. We determined the extent of association between the apoptosis regulators Bcl-xL and tBid at the mitochondrial outer membrane of living cells and discovered that practically all mitochondria-bound Bcl-xL and tBid are associated with each other, in contrast to undetectable association in the cytosol. Furthermore, we show further applicability of our method to other mitochondrial proteins, as well as to proteins in the endoplasmic reticulum (ER) membrane.
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Affiliation(s)
- Joseph D Unsay
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076, Tübingen, Germany
- Max Planck Insitute for Intteligen Systems, Heisenbergstrasse 3, 70569, Stuttgart, Germany
- German Cancer Research Center, Im Neuenheimer Feld 280, 62120, Heidelberg, Germany
| | - Fabronia Murad
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076, Tübingen, Germany
| | - Eduard Hermann
- Max Planck Insitute for Intteligen Systems, Heisenbergstrasse 3, 70569, Stuttgart, Germany
| | - Jonas Ries
- European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117, Heidelberg, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076, Tübingen, Germany
- Max Planck Insitute for Intteligen Systems, Heisenbergstrasse 3, 70569, Stuttgart, Germany
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13
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Schneider F, Waithe D, Lagerholm BC, Shrestha D, Sezgin E, Eggeling C, Fritzsche M. Statistical Analysis of Scanning Fluorescence Correlation Spectroscopy Data Differentiates Free from Hindered Diffusion. ACS NANO 2018; 12:8540-8546. [PMID: 30028588 PMCID: PMC6117752 DOI: 10.1021/acsnano.8b04080] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 07/20/2018] [Indexed: 05/28/2023]
Abstract
Cells rely on versatile diffusion dynamics in their plasma membrane. Quantification of this often heterogeneous diffusion is essential to the understanding of cell regulation and function. Yet such measurements remain a major challenge in cell biology, usually due to low sampling throughput, a necessity for dedicated equipment, sophisticated fluorescent label strategies, and limited sensitivity. Here, we introduce a robust, broadly applicable statistical analysis pipeline for large scanning fluorescence correlation spectroscopy data sets, which uncovers the nanoscale heterogeneity of the plasma membrane in living cells by differentiating free from hindered diffusion modes of fluorescent lipid and protein analogues.
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Affiliation(s)
- Falk Schneider
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
| | - Dominic Waithe
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
| | - B. Christoffer Lagerholm
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
| | - Dilip Shrestha
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
| | - Erdinc Sezgin
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
| | - Christian Eggeling
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
- Institute of Applied
Optics, Friedrich-Schiller-University and
Leibniz Institute of Photonic Technology, Helmholtzweg 4, 07743 Jena, Germany
| | - Marco Fritzsche
- MRC
Human Immunology Unit, Wolfson Imaging Centre Oxford, and MRC Centre for Computational Biology, Weatherall Institute of Molecular Medicine, University
of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
- Kennedy
Institute for Rheumatology, University of
Oxford, Roosevelt Drive, Oxford OX3 7LF, United Kingdom
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14
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Mattes B, Dang Y, Greicius G, Kaufmann LT, Prunsche B, Rosenbauer J, Stegmaier J, Mikut R, Özbek S, Nienhaus GU, Schug A, Virshup DM, Scholpp S. Wnt/PCP controls spreading of Wnt/β-catenin signals by cytonemes in vertebrates. eLife 2018; 7:36953. [PMID: 30060804 PMCID: PMC6086664 DOI: 10.7554/elife.36953] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 07/16/2018] [Indexed: 12/31/2022] Open
Abstract
Signaling filopodia, termed cytonemes, are dynamic actin-based membrane structures that regulate the exchange of signaling molecules and their receptors within tissues. However, how cytoneme formation is regulated remains unclear. Here, we show that Wnt/planar cell polarity (PCP) autocrine signaling controls the emergence of cytonemes, and that cytonemes subsequently control paracrine Wnt/β-catenin signal activation. Upon binding of the Wnt family member Wnt8a, the receptor tyrosine kinase Ror2 becomes activated. Ror2/PCP signaling leads to the induction of cytonemes, which mediate the transport of Wnt8a to neighboring cells. In the Wnt-receiving cells, Wnt8a on cytonemes triggers Wnt/β-catenin-dependent gene transcription and proliferation. We show that cytoneme-based Wnt transport operates in diverse processes, including zebrafish development, murine intestinal crypt and human cancer organoids, demonstrating that Wnt transport by cytonemes and its control via the Ror2 pathway is highly conserved in vertebrates. Communication helps the cells that make up tissues and organs to work together as a team. One way that cells share information with each other as tissues grow and develop is by exchanging signaling proteins. These interact with receptors on the surface of other cells; this causes the cell to change how it behaves. The Wnt family of signaling proteins orchestrate organ development. Wnt proteins influence which types of cells develop, how fast they divide, and how and when they move. Relatively few cells, or small groups of cells, in developing tissues produce Wnt proteins, while larger groups nearby respond to the signals. We do not fully understand how Wnt proteins travel between cells, but recent work revealed an unexpected mechanism – cells seem to hand-deliver their messages. Finger-like structures called cytonemes grow out of the cell membrane and carry Wnt proteins to their destination. If the cytonemes do not form properly the target cells do not behave correctly, which can lead to severe tissue malformation. Mattes et al. have now investigated how cytonemes form using a combination of state-of-the-art genetic and high-resolution imaging techniques. In initial experiments involving zebrafish cells that were grown in the laboratory, Mattes et al. found that the Wnt proteins kick start their own transport; before they travel to their destination, they act on the cells that made them. A Wnt protein called Wnt8a activates the receptor Ror2 on the surface of the signal-producing cell. Ror2 then triggers signals inside the cell that begin the assembly of the cytonemes. The more Ror2 is activated, the more cytonemes the cell makes, and the more Wnt signals it can send out. This mechanism operates in various tissues: Ror2 also controls the cytoneme transport process in living zebrafish embryos, the mouse intestine and human stomach tumors. This knowledge will help researchers to develop new ways to control Wnt signaling, which could help to produce new treatments for diseases ranging from cancers (for example in the stomach and bowel) to degenerative diseases such as Alzheimer’s disease.
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Affiliation(s)
- Benjamin Mattes
- Living Systems Institute, School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom.,Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Yonglong Dang
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Gediminas Greicius
- Program in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore, Singapore
| | | | - Benedikt Prunsche
- Institute of Applied Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Jakob Rosenbauer
- John von Neumann Institute for Computing, Jülich Supercomputing Centre, Jülich, Germany
| | - Johannes Stegmaier
- Institute for Automation and Applied Informatics, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Imaging and Computer Vision, RWTH Aachen University, Aachen, Germany
| | - Ralf Mikut
- Institute for Automation and Applied Informatics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Suat Özbek
- Centre of Organismal Studies, University of Heidelberg, Karlsruhe, Germany
| | - Gerd Ulrich Nienhaus
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Applied Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Alexander Schug
- John von Neumann Institute for Computing, Jülich Supercomputing Centre, Jülich, Germany.,Steinbuch Centre for Computing, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - David M Virshup
- Program in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore, Singapore
| | - Steffen Scholpp
- Living Systems Institute, School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom.,Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany
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15
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Dunsing V, Luckner M, Zühlke B, Petazzi RA, Herrmann A, Chiantia S. Optimal fluorescent protein tags for quantifying protein oligomerization in living cells. Sci Rep 2018; 8:10634. [PMID: 30006597 PMCID: PMC6045628 DOI: 10.1038/s41598-018-28858-0] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 07/02/2018] [Indexed: 11/30/2022] Open
Abstract
Fluorescence fluctuation spectroscopy has become a popular toolbox for non-disruptive analysis of molecular interactions in living cells. The quantification of protein oligomerization in the native cellular environment is highly relevant for a detailed understanding of complex biological processes. An important parameter in this context is the molecular brightness, which serves as a direct measure of oligomerization and can be easily extracted from temporal or spatial fluorescence fluctuations. However, fluorescent proteins (FPs) typically used in such studies suffer from complex photophysical transitions and limited maturation, inducing non-fluorescent states. Here, we show how these processes strongly affect molecular brightness measurements. We perform a systematic characterization of non-fluorescent states for commonly used FPs and provide a simple guideline for accurate, unbiased oligomerization measurements in living cells. Further, we focus on novel red FPs and demonstrate that mCherry2, an mCherry variant, possesses superior properties with regards to precise quantification of oligomerization.
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Affiliation(s)
- Valentin Dunsing
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Madlen Luckner
- Institute for Biology, IRI Life Sciences, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Boris Zühlke
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Roberto A Petazzi
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Andreas Herrmann
- Institute for Biology, IRI Life Sciences, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Salvatore Chiantia
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany.
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16
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Beloqui A, Kobitski AY, Nienhaus GU, Delaittre G. A simple route to highly active single-enzyme nanogels. Chem Sci 2018; 9:1006-1013. [PMID: 29675147 PMCID: PMC5883864 DOI: 10.1039/c7sc04438k] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 11/30/2017] [Indexed: 11/25/2022] Open
Abstract
We have established a simple one-step synthesis of single-enzyme nanogels (SENs), i.e., nanobiocatalysts consisting of an enzyme molecule embedded in a hydrophilic, polymeric crosslinked nanostructure, as a most attractive approach to enhance the stability of enzymes. In contrast to earlier protocols, we demonstrate here that the addition of a small amount of sucrose makes the nanogel formation equally effective as earlier two-step protocols requiring enzyme pre-modification. This provides the dual advantage of skipping a synthetic step and preserving the surface chemistry of the enzymes, hence their native structure. Enzymes encapsulated in this way exhibit a high catalytic activity, similar to that of the free enzymes, in a markedly widened pH range. With our method, the thickness of the hydrogel layer can be finely tuned by careful adjustment of reaction parameters. This is most important because the shell thickness strongly affects both enzyme activity and stability, as we observe for a wide selection of proteins. Finally, a single-molecule analysis by means of two-color confocal fluorescence coincidence analysis confirms that our encapsulation method is highly efficient and suppresses the occurrence of nanoparticles lacking an enzyme molecule. The proposed method is therefore highly attractive for biocatalysis applications, ensuring a high activity and stability of the enzymes.
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Affiliation(s)
- Ana Beloqui
- Institute of Toxicology and Genetics , Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1 , 76344 Eggenstein-Leopoldshafen , Germany . ;
- Preparative Macromolecular Chemistry , Institute for Technical Chemistry and Polymer Chemistry , Karlsruhe Institute of Technology (KIT) , Engesserstrasse 15 , 76131 Karlsruhe , Germany
| | - Andrei Yu Kobitski
- Institute of Applied Physics , Karlsruhe Institute of Technology (KIT) , Wolfgang-Gaede-Strasse 1 , 76131 Karlsruhe , Germany
| | - Gerd Ulrich Nienhaus
- Institute of Toxicology and Genetics , Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1 , 76344 Eggenstein-Leopoldshafen , Germany . ;
- Institute of Applied Physics , Karlsruhe Institute of Technology (KIT) , Wolfgang-Gaede-Strasse 1 , 76131 Karlsruhe , Germany
- Institute of Nanotechnology , Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1 , 76344 Eggenstein-Leopoldshafen , Germany
- Department of Physics , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , USA
| | - Guillaume Delaittre
- Institute of Toxicology and Genetics , Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1 , 76344 Eggenstein-Leopoldshafen , Germany . ;
- Preparative Macromolecular Chemistry , Institute for Technical Chemistry and Polymer Chemistry , Karlsruhe Institute of Technology (KIT) , Engesserstrasse 15 , 76131 Karlsruhe , Germany
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17
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Dunsing V, Mayer M, Liebsch F, Multhaup G, Chiantia S. Direct evidence of amyloid precursor-like protein 1 trans interactions in cell-cell adhesion platforms investigated via fluorescence fluctuation spectroscopy. Mol Biol Cell 2017; 28:3609-3620. [PMID: 29021345 PMCID: PMC5706989 DOI: 10.1091/mbc.e17-07-0459] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/13/2017] [Accepted: 10/04/2017] [Indexed: 01/25/2023] Open
Abstract
The amyloid precursor–like protein 1 (APLP1) plays a role in synaptic adhesion and synaptogenesis. In this work, we use quantitative fluorescence microscopy to demonstrate the existence of APLP1–APLP1 trans interaction across cell–cell junctions and propose a model explaining the molecular mechanism driving APLP1 multimerization. The amyloid precursor–like protein 1 (APLP1) is a type I transmembrane protein that plays a role in synaptic adhesion and synaptogenesis. Past investigations indicated that APLP1 is involved in the formation of protein–protein complexes that bridge the junctions between neighboring cells. Nevertheless, APLP1–APLP1 trans interactions have never been directly observed in higher eukaryotic cells. Here, we investigated APLP1 interactions and dynamics directly in living human embryonic kidney cells using fluorescence fluctuation spectroscopy techniques, namely cross-correlation scanning fluorescence correlation spectroscopy and number and brightness analysis. Our results show that APLP1 forms homotypic trans complexes at cell–cell contacts. In the presence of zinc ions, the protein forms macroscopic clusters, exhibiting an even higher degree of trans binding and strongly reduced dynamics. Further evidence from giant plasma membrane vesicles suggests that the presence of an intact cortical cytoskeleton is required for zinc-induced cis multimerization. Subsequently, large adhesion platforms bridging interacting cells are formed through APLP1–APLP1 trans interactions. Taken together, our results provide direct evidence that APLP1 functions as a neuronal zinc-dependent adhesion protein and allow a more detailed understanding of the molecular mechanisms driving the formation of APLP1 adhesion platforms.
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Affiliation(s)
- Valentin Dunsing
- Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
| | - Magnus Mayer
- Institute of Chemistry and Biochemistry, Free University of Berlin, 14195 Berlin, Germany
| | - Filip Liebsch
- Department of Pharmacology and Therapeutics/Integrated Program in Neuroscience, McGill University, Montreal, QC H3G 1Y63, Canada
| | - Gerhard Multhaup
- Department of Pharmacology and Therapeutics/Integrated Program in Neuroscience, McGill University, Montreal, QC H3G 1Y63, Canada
| | - Salvatore Chiantia
- Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
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18
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Nienhaus K, Nienhaus GU. Chromophore photophysics and dynamics in fluorescent proteins of the GFP family. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:443001. [PMID: 27604321 DOI: 10.1088/0953-8984/28/44/443001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Proteins of the green fluorescent protein (GFP) family are indispensable for fluorescence imaging experiments in the life sciences, particularly of living specimens. Their essential role as genetically encoded fluorescence markers has motivated many researchers over the last 20 years to further advance and optimize these proteins by using protein engineering. Amino acids can be exchanged by site-specific mutagenesis, starting with naturally occurring proteins as templates. Optical properties of the fluorescent chromophore are strongly tuned by the surrounding protein environment, and a targeted modification of chromophore-protein interactions requires a profound knowledge of the underlying photophysics and photochemistry, which has by now been well established from a large number of structural and spectroscopic experiments and molecular-mechanical and quantum-mechanical computations on many variants of fluorescent proteins. Nevertheless, such rational engineering often does not meet with success and thus is complemented by random mutagenesis and selection based on the optical properties. In this topical review, we present an overview of the key structural and spectroscopic properties of fluorescent proteins. We address protein-chromophore interactions that govern ground state optical properties as well as processes occurring in the electronically excited state. Special emphasis is placed on photoactivation of fluorescent proteins. These light-induced reactions result in large structural changes that drastically alter the fluorescence properties of the protein, which enables some of the most exciting applications, including single particle tracking, pulse chase imaging and super-resolution imaging. We also present a few examples of fluorescent protein application in live-cell imaging experiments.
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Affiliation(s)
- Karin Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), Wolfgang Gaede-Straße 1, 76131 Karlsruhe, Germany
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19
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Multiplexed imaging of intracellular protein networks. Cytometry A 2016; 89:761-75. [DOI: 10.1002/cyto.a.22876] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 04/21/2016] [Accepted: 04/26/2016] [Indexed: 12/19/2022]
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20
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Nienhaus K, Nienhaus GU. Where Do We Stand with Super-Resolution Optical Microscopy? J Mol Biol 2016; 428:308-322. [DOI: 10.1016/j.jmb.2015.12.020] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 12/23/2015] [Accepted: 12/23/2015] [Indexed: 10/22/2022]
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