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Lou J, Deng Q, Zhang X, Bell C, Das A, Bediaga N, Zlatic C, Johanson T, Allan R, Griffin MW, Paradkar P, Harvey K, Dawson M, Hinde E. Heterochromatin protein 1 alpha (HP1α) undergoes a monomer to dimer transition that opens and compacts live cell genome architecture. Nucleic Acids Res 2024; 52:10918-10933. [PMID: 39193905 PMCID: PMC11472067 DOI: 10.1093/nar/gkae720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 07/29/2024] [Accepted: 08/07/2024] [Indexed: 08/29/2024] Open
Abstract
Our understanding of heterochromatin nanostructure and its capacity to mediate gene silencing in a living cell has been prevented by the diffraction limit of optical microscopy. Thus, here to overcome this technical hurdle, and directly measure the nucleosome arrangement that underpins this dense chromatin state, we coupled fluorescence lifetime imaging microscopy (FLIM) of Förster resonance energy transfer (FRET) between histones core to the nucleosome, with molecular editing of heterochromatin protein 1 alpha (HP1α). Intriguingly, this super-resolved readout of nanoscale chromatin structure, alongside fluorescence fluctuation spectroscopy (FFS) and FLIM-FRET analysis of HP1α protein-protein interaction, revealed nucleosome arrangement to be differentially regulated by HP1α oligomeric state. Specifically, we found HP1α monomers to impart a previously undescribed global nucleosome spacing throughout genome architecture that is mediated by trimethylation on lysine 9 of histone H3 (H3K9me3) and locally reduced upon HP1α dimerisation. Collectively, these results demonstrate HP1α to impart a dual action on chromatin that increases the dynamic range of nucleosome proximity. We anticipate that this finding will have important implications for our understanding of how live cell heterochromatin structure regulates genome function.
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Affiliation(s)
- Jieqiong Lou
- School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Qiji Deng
- Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC 3000, Australia
| | - Xiaomeng Zhang
- School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Charles C Bell
- Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC 3000, Australia
| | - Andrew B Das
- Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC 3000, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Naiara G Bediaga
- Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC 3000, Australia
| | - Courtney O Zlatic
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Timothy M Johanson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Rhys S Allan
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Michael D W Griffin
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC 3010, Australia
| | - PrasadN Paradkar
- CSIRO Health & Biosecurity, Australian Centre for Disease Preparedness, 5 Portarlington Road, Geelong3220, Australia
| | - Kieran F Harvey
- Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC 3000, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, VIC 3010, Australia
- Department of Anatomy and Developmental Biology and Biomedicine Discovery Institute, Monash University, Clayton, VIC 3168, Australia
| | - Mark A Dawson
- Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC 3000, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, VIC 3010, Australia
- Centre for Cancer Research, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Elizabeth Hinde
- School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC 3010, Australia
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2
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Amiar S, Johnson KA, Husby ML, Marzi A, Stahelin RV. A fatty acid ordered plasma membrane environment is critical for Ebola virus matrix protein assembly and budding. J Lipid Res 2024:100663. [PMID: 39369791 DOI: 10.1016/j.jlr.2024.100663] [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: 06/11/2024] [Revised: 09/23/2024] [Accepted: 09/25/2024] [Indexed: 10/08/2024] Open
Abstract
Plasma membrane (PM) domains and order phases have been shown to play a key role in the assembly, release, and entry of several lipid-enveloped viruses. In the present study, we provide a mechanistic understanding of the Ebola virus (EBOV) matrix protein VP40 interaction with PM lipids and their effect on VP40 oligomerization, a crucial step for viral assembly and budding. VP40 matrix formation is sufficient to induce changes in the PM fluidity. We demonstrate that the distance between the lipid headgroups, the fatty acid tail saturation and the PM order are important factors for the stability of VP40 binding and oligomerization at the PM. Use of FDA-approved drugs to fluidize the PM, destabilizes the viral matrix assembly leading to a reduction in budding efficiency. Overall, these findings support an EBOV assembly mechanism that reaches beyond lipid headgroup specificity by using ordered PM lipid regions independent of cholesterol.
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Affiliation(s)
- Souad Amiar
- Borch Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA; Purdue Institute of Inflammation, Immunology, and Infectious Disease (PI4D), Purdue University, West Lafayette, Indiana, USA
| | - Kristen A Johnson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Monica L Husby
- Borch Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA
| | - Andrea Marzi
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, 59840, USA
| | - Robert V Stahelin
- Borch Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA; Purdue Institute of Inflammation, Immunology, and Infectious Disease (PI4D), Purdue University, West Lafayette, Indiana, USA.
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3
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Yerramilli VS, Lin G, Reisinger JL, Hemmerlin RM, Lindberg SK, Plante K, Ross AH, Gericke A, Scarlata S. The scaffolding protein IQGAP1 enhances EGFR signaling by Promoting Oligomerization and Preventing Degradation. J Biol Chem 2024:107844. [PMID: 39357822 DOI: 10.1016/j.jbc.2024.107844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Revised: 09/05/2024] [Accepted: 09/19/2024] [Indexed: 10/04/2024] Open
Abstract
IQGAP1 is a large, multi-domain scaffold that connects and modulates different signaling networks including the one initiated by epidermal growth factor (EGF). In this study, we have used live cell fluorescence imaging methods along with other biochemical techniques to follow the mechanisms used by IQGAP1 to enhance EGF signaling. We show that IQGAP1 enhances EGF signaling by promoting the oligomerization of its receptor, EGFR, upon EGF addition along with concurrent IQGAP oligomerization. Using cellular markers, we find that IQGAP1 promotes the plasma membrane localization of EGFR and promotes association to one of its phosphoinositide lipid pathway ligands, PI(3,4,5)P3. Additionally, we find that binding of EGFR to IQGAP1 protects EGFR from lysosomal degradation. Taken together, our results show that IQGAP1 enhances EGF-mediated pathway progression through mechanisms that augment simple scaffolding activities.
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Affiliation(s)
- V Siddartha Yerramilli
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01605, USA
| | - Guanyu Lin
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01605, USA
| | - Jessica L Reisinger
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01605, USA
| | - Rachel M Hemmerlin
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01605, USA
| | - Samantha K Lindberg
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01605, USA
| | - Karin Plante
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01605, USA
| | - Alonzo H Ross
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01605, USA; Department of Biochemistry and Molecular Pharmacology University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Arne Gericke
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01605, USA
| | - Suzanne Scarlata
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01605, USA.
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4
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Schneider F, Cespedes PF, Karedla N, Dustin ML, Fritzsche M. Quantifying biomolecular organisation in membranes with brightness-transit statistics. Nat Commun 2024; 15:7082. [PMID: 39152104 PMCID: PMC11329664 DOI: 10.1038/s41467-024-51435-1] [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: 03/05/2024] [Accepted: 08/07/2024] [Indexed: 08/19/2024] Open
Abstract
Cells crucially rely on the interactions of biomolecules at their plasma membrane to maintain homeostasis. Yet, a methodology to systematically quantify biomolecular organisation, measuring diffusion dynamics and oligomerisation, represents an unmet need. Here, we introduce the brightness-transit statistics (BTS) method based on fluorescence fluctuation spectroscopy and combine information from brightness and transit times to elucidate biomolecular diffusion and oligomerisation in both cell-free in vitro and in vitro systems incorporating living cells. We validate our approach in silico with computer simulations and experimentally using oligomerisation of EGFP tethered to supported lipid bilayers. We apply our pipeline to study the oligomerisation of CD40 ectodomain in vitro and endogenous CD40 on primary B cells. While we find a potential for CD40 to oligomerize in a concentration or ligand depended manner, we do not observe mobile oligomers on B cells. The BTS method combines sensitive analysis, quantification, and intuitive visualisation of dynamic biomolecular organisation.
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Affiliation(s)
- Falk Schneider
- Kennedy Institute for Rheumatology, Roosevelt Drive, University of Oxford, Oxford, OX3 7LF, United Kingdom.
- Translational Imaging Center, University of Southern California, Los Angeles, California, 90089, United States of America.
| | - Pablo F Cespedes
- Kennedy Institute for Rheumatology, Roosevelt Drive, University of Oxford, Oxford, OX3 7LF, United Kingdom
| | - Narain Karedla
- Kennedy Institute for Rheumatology, Roosevelt Drive, University of Oxford, Oxford, OX3 7LF, United Kingdom
- Rosalind Franklin Institute, Harwell Campus, Didcot, OX11 0FA, United Kingdom
| | - Michael L Dustin
- Kennedy Institute for Rheumatology, Roosevelt Drive, University of Oxford, Oxford, OX3 7LF, United Kingdom
| | - Marco Fritzsche
- Kennedy Institute for Rheumatology, Roosevelt Drive, University of Oxford, Oxford, OX3 7LF, United Kingdom.
- Rosalind Franklin Institute, Harwell Campus, Didcot, OX11 0FA, United Kingdom.
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5
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Foust DJ, Piston DW. Measuring G protein activation by spectrally resolved imaging fluorescence fluctuation spectroscopy. Biophys J 2024:S0006-3495(24)00552-6. [PMID: 39148292 DOI: 10.1016/j.bpj.2024.08.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 06/21/2024] [Accepted: 08/12/2024] [Indexed: 08/17/2024] Open
Abstract
The activation of heterotrimeric G proteins through G-protein-coupled receptors (GPCRs) is a ubiquitous signaling mechanism in eukaryotic biology. The three principal molecular components of this cascade are the GPCR, Gα subunit, and Gβγ subunit. Measurement of interactions between these components and their downstream effectors in live cells is paramount to understanding how cells fine-tune their physiology in response to many external stimuli. Multicolor fluorescence fluctuation spectroscopy (FFS) approaches allow the sensitive detection of heteromeric interactions by using spectrally distinct fluorophores to label biomolecules of interest. We considered three imaging FFS approaches to measuring molecular interactions from the signals produced by a spectrally resolved confocal microscopy: raster spectral image correlation spectroscopy (RSICS), spectral spatial cumulant analysis, and native resolution spatial cumulant analysis. We characterized these approaches using simulation and experiments on heteromers with known stoichiometries. We found that RSICS had the best sensitivity for measuring heteromeric interactions and employed it to measure G protein complexes. As measured by RSICS, interactions between the G protein subunits Gαi1 and Gβ1γ2 were sensitive to the stimulation of two GPCRs, the D2 dopamine receptor and the α-2A adrenergic receptor. Interactions between GPCRs and G proteins were not detectable above background, supporting a collisional model of GPCR/G protein interactions in contrast to a preassembly model where strong interactions would be present. These data are uniquely available by this FFS framework, which is appropriate for not only multiplexed measurements of G protein biology but any dynamic protein complexes in the cell.
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Affiliation(s)
- Daniel J Foust
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri; Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri
| | - David W Piston
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri.
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6
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Jabloñski M, Luque GM, Gómez-Elías MD, Sanchez-Cardenas C, Xu X, de la Vega-Beltran JL, Corkidi G, Linares A, Abonza Amaro VX, Arenas-Hernandez A, Del Pilar Ramos-Godinez M, López-Saavedra A, Krapf D, Krapf D, Darszon A, Guerrero A, Buffone MG. Reorganization of the Flagellum Scaffolding Induces a Sperm Standstill During Fertilization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.06.22.546073. [PMID: 37904966 PMCID: PMC10614747 DOI: 10.1101/2023.06.22.546073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Mammalian sperm delve into the female reproductive tract to fertilize the female gamete. The available information about how sperm regulate their motility during the final journey to the fertilization site is extremely limited. In this work, we investigated the structural and functional changes in the sperm flagellum after AE and during the interaction with the eggs. The evidence demonstrates that the double helix actin network surrounding the mitochondrial sheath of the midpiece undergoes structural changes prior to the motility cessation. This structural modification is accompanied by a decrease in diameter of the midpiece and is driven by intracellular calcium changes that occur concomitant with a reorganization of the actin helicoidal cortex. Midpiece contraction occurs in a subset of cells that undergo AE, live-cell imaging during in vitro fertilization showed that the midpiece contraction is required for motility cessation after fusion is initiated. These findings provide the first evidence of the F-actin network's role in regulating sperm motility, adapting its function to meet specific cellular requirements during fertilization, and highlighting the broader significance of understanding sperm motility. Significant statement In this work, we demonstrate that the helical structure of polymerized actin in the flagellum undergoes a rearrangement at the time of sperm-egg fusion. This process is driven by intracellular calcium and promotes a decrease in the sperm midpiece diameter as well as the arrest in motility, which is observed after the fusion process is initiated.
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7
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Barylko B, Taylor CA, Wang J, Hedde PN, Chen Y, Hur KH, Binns DD, Brautigam CA, DeMartino GN, Mueller JD, Jameson DM, Albanesi JP. Analysis of Arc/Arg3.1 Oligomerization In Vitro and in Living Cells. Int J Mol Sci 2024; 25:6454. [PMID: 38928159 PMCID: PMC11203824 DOI: 10.3390/ijms25126454] [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: 05/24/2024] [Accepted: 06/06/2024] [Indexed: 06/28/2024] Open
Abstract
Arc (also known as Arg3.1) is an activity-dependent immediate early gene product enriched in neuronal dendrites. Arc plays essential roles in long-term potentiation, long-term depression, and synaptic scaling. Although its mechanisms of action in these forms of synaptic plasticity are not completely well established, the activities of Arc include the remodeling of the actin cytoskeleton, the facilitation of AMPA receptor (AMPAR) endocytosis, and the regulation of the transcription of AMPAR subunits. In addition, Arc has sequence and structural similarity to retroviral Gag proteins and self-associates into virus-like particles that encapsulate mRNA and perhaps other cargo for intercellular transport. Each of these activities is likely to be influenced by Arc's reversible self-association into multiple oligomeric species. Here, we used mass photometry to show that Arc exists predominantly as monomers, dimers, and trimers at approximately 20 nM concentration in vitro. Fluorescence fluctuation spectroscopy revealed that Arc is almost exclusively present as low-order (monomer to tetramer) oligomers in the cytoplasm of living cells, over a 200 nM to 5 μM concentration range. We also confirmed that an α-helical segment in the N-terminal domain contains essential determinants of Arc's self-association.
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Affiliation(s)
- Barbara Barylko
- Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park, Dallas, TX 75390, USA; (B.B.); (C.A.T.4th); (D.D.B.)
| | - Clinton A. Taylor
- Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park, Dallas, TX 75390, USA; (B.B.); (C.A.T.4th); (D.D.B.)
| | - Jason Wang
- Department of Physiology, University of Texas Southwestern Medical Center, 6001 Forest Park, Dallas, TX 75390, USA; (J.W.); (G.N.D.)
| | - Per Niklas Hedde
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo St., BSB 222, Honolulu, HI 96813, USA;
- Laboratory for Fluorescence Dynamics, University of California, Irvine, CA 92697, USA
| | - Yan Chen
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA; (Y.C.); (K.-H.H.); (J.D.M.)
| | - Kwang-Ho Hur
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA; (Y.C.); (K.-H.H.); (J.D.M.)
| | - Derk D. Binns
- Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park, Dallas, TX 75390, USA; (B.B.); (C.A.T.4th); (D.D.B.)
| | - Chad A. Brautigam
- Department of Biophysics, University of Texas Southwestern Medical Center, 6001 Forest Park, Dallas, TX 75390, USA;
| | - George N. DeMartino
- Department of Physiology, University of Texas Southwestern Medical Center, 6001 Forest Park, Dallas, TX 75390, USA; (J.W.); (G.N.D.)
| | - Joachim D. Mueller
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA; (Y.C.); (K.-H.H.); (J.D.M.)
| | - David M. Jameson
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo St., BSB 222, Honolulu, HI 96813, USA;
| | - Joseph P. Albanesi
- Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park, Dallas, TX 75390, USA; (B.B.); (C.A.T.4th); (D.D.B.)
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8
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Cheraghi H, Kovács KD, Székács I, Horvath R, Szabó B. Continuous distribution of cancer cells in the cell cycle unveiled by AI-segmented imaging of 37,000 HeLa FUCCI cells. Heliyon 2024; 10:e30239. [PMID: 38707416 PMCID: PMC11066426 DOI: 10.1016/j.heliyon.2024.e30239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 04/22/2024] [Accepted: 04/22/2024] [Indexed: 05/07/2024] Open
Abstract
Classification of live or fixed cells based on their unlabeled microscopic images would be a powerful tool for cell biology and pathology. For such software, the first step is the generation of a ground truth database that can be used for training and testing AI classification algorithms. The Application of cells expressing fluorescent reporter proteins allows the building of ground truth datasets in a straightforward way. In this study, we present an automated imaging pipeline utilizing the Cellpose algorithm for the precise cell segmentation and measurement of fluorescent cellular intensities across multiple channels. We analyzed the cell cycle of HeLa-FUCCI cells expressing fluorescent red and green reporter proteins at various levels depending on the cell cycle state. To build the dataset, 37,000 fixed cells were automatically scanned using a standard motorized microscope, capturing phase contrast and fluorescent red/green images. The fluorescent pixel intensity of each cell was integrated to calculate the total fluorescence of cells based on cell segmentation in the phase contrast channel. It resulted in a precise intensity value for each cell in both channels. Furthermore, we conducted a comparative analysis of Cellpose 1.0 and Cellpose 2.0 in cell segmentation performance. Cellpose 2.0 demonstrated notable improvements, achieving a significantly reduced false positive rate of 2.7 % and 1.4 % false negative. The cellular fluorescence was visualized in a 2D plot (map) based on the red and green intensities of the FUCCI construct revealing the continuous distribution of cells in the cell cycle. This 2D map enables the selection and potential isolation of single cells in a specific phase. In the corresponding heatmap, two clusters appeared representing cells in the red and green states. Our pipeline allows the high-throughput and accurate measurement of cellular fluorescence providing extensive statistical information on thousands of cells with potential applications in developmental and cancer biology. Furthermore, our method can be used to build ground truth datasets automatically for training and testing AI cell classification. Our automated pipeline can be used to analyze thousands of cells within 2 h after putting the sample onto the microscope.
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Affiliation(s)
- Hamid Cheraghi
- Department of Biological Physics, Eötvös University (ELTE), H-1117, Budapest, Hungary
- CellSorter Scientific Company for Innovations, Prielle Kornélia utca 4A, 1117, Budapest, Hungary
| | - Kinga Dóra Kovács
- Department of Biological Physics, Eötvös University (ELTE), H-1117, Budapest, Hungary
- Nanobiosensorics Laboratory, HUN-REN, Institute of Technical Physics and Materials Science, Centre for Energy Research, Budapest, Hungary
| | - Inna Székács
- Nanobiosensorics Laboratory, HUN-REN, Institute of Technical Physics and Materials Science, Centre for Energy Research, Budapest, Hungary
| | - Robert Horvath
- Nanobiosensorics Laboratory, HUN-REN, Institute of Technical Physics and Materials Science, Centre for Energy Research, Budapest, Hungary
| | - Bálint Szabó
- Department of Biological Physics, Eötvös University (ELTE), H-1117, Budapest, Hungary
- CellSorter Scientific Company for Innovations, Prielle Kornélia utca 4A, 1117, Budapest, Hungary
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9
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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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10
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Clayton AHA. Photobleaching FRET-FLIM-ICS for quaternary structure quantification on cells. Theory and simulations. Biochim Biophys Acta Gen Subj 2024; 1868:130618. [PMID: 38621595 DOI: 10.1016/j.bbagen.2024.130618] [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: 12/14/2023] [Revised: 04/04/2024] [Accepted: 04/12/2024] [Indexed: 04/17/2024]
Abstract
The oligomerization of proteins is an important biological control mechanism and has several functions in activity and stability of enzymes, structural proteins, ion channels and transcription factors. The determination of the relevant oligomeric states in terms of geometry (spatial extent), oligomer size (monomer or dimer or oligomer) and affinity (amounts of monomer, dimer and oligomer) is a challenging biophysical problem. Förster resonance energy transfer and fluorescence fluctuation spectroscopy are powerful tools that are sensitive to proximity and oligomerization respectively. Here it is proposed to combine image-based lifetime-detected Forster resonance energy transfer with image correlation spectroscopy and photobleaching to determine distances, oligomer sizes and oligomer distributions. Simulations for simple oligomeric forms illustrate the potential to improve the discrimination between different quaternary states in the cellular milieu.
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Affiliation(s)
- Andrew H A Clayton
- Cell Biophysics Laboratory, Optical Sciences Centre, Department of Physics and Astronomy, School of Science, Computer, and Engineering Sciences, Swinburne University of Technology, Melbourne, Australia.
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11
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Scarlata S. Unraveling Hidden Cell Signaling Pathways Using Biophysical Methods: Application to the Gαq/Phospholipase Cβ Signaling System. J Phys Chem B 2024; 128:2057-2064. [PMID: 38388346 DOI: 10.1021/acs.jpcb.4c00343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
The success of pharmaceutical therapies relies on how well cells respond to a particular drug, but accurately predicting responses can be difficult due to the complex and numerous potential molecular interactions that are possible in cells, and the responses of individuals can be variable due to cryptic and unexpected interactions. With the advancement of proteomics and fluorescence imaging methods, it is now possible to elucidate novel secondary signaling pathways and predict unexpected responses that might otherwise be missed, allowing for the development of better therapeutics. The Gαq/PLCβ signaling pathway is activated by agents that mediate allergic responses, neurotransmission, and heart rate, as well as other functions that are critical for survival. This Review describes the factors that must be considered in delineating signaling pathways and describes the novel translational role that we have uncovered for this signaling pathway.
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Affiliation(s)
- Suzanne Scarlata
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, Massachusetts 01609, United States
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12
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Fettweis G, Johnson TA, Almeida‐Prieto B, Weller‐Pérez J, Presman DM, Hager GL, Alvarez de la Rosa D. The mineralocorticoid receptor forms higher order oligomers upon DNA binding. Protein Sci 2024; 33:e4890. [PMID: 38160317 PMCID: PMC10868434 DOI: 10.1002/pro.4890] [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: 07/12/2023] [Revised: 11/30/2023] [Accepted: 12/24/2023] [Indexed: 01/03/2024]
Abstract
The prevailing model of steroid hormone nuclear receptor function assumes ligand-induced homodimer formation followed by binding to DNA hormone response elements (HREs). This model has been challenged by evidence showing that the glucocorticoid receptor (GR) forms tetramers upon ligand and DNA binding, which then drive receptor-mediated gene transactivation and transrepression. GR and the closely-related mineralocorticoid receptors (MR) interact to transduce corticosteroid hormone signaling, but whether they share the same quaternary arrangement is unknown. Here, we used a fluorescence imaging technique, Number & Brightness, to study oligomerization in a cell system allowing real-time analysis of receptor-DNA interactions. Agonist-bound MR forms tetramers in the nucleoplasm and higher order oligomers upon binding to HREs. Antagonists form intermediate-size quaternary arrangements, suggesting that large oligomers are essential for function. Divergence between MR and GR quaternary structure is driven by different functionality of known and new multimerization interfaces, which does not preclude formation of heteromers. Thus, influencing oligomerization may be important to selectively modulate corticosteroid signaling.
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Affiliation(s)
- Gregory Fettweis
- Laboratory of Receptor Biology and Gene ExpressionNational Cancer Institute, National Institutes of HealthBethesdaMarylandUSA
- Present address:
Laboratory of Gene Expression and Cancer, GIGA‐Molecular Biology of DiseaseUniversity of LiègeLiègeBelgium
| | - Thomas A. Johnson
- Laboratory of Receptor Biology and Gene ExpressionNational Cancer Institute, National Institutes of HealthBethesdaMarylandUSA
| | - Brian Almeida‐Prieto
- Departmento de Ciencias Médicas Básicas and Instituto de Tecnologías BiomédicasUniversidad de La LagunaLa LagunaSpain
| | - Julián Weller‐Pérez
- Departmento de Ciencias Médicas Básicas and Instituto de Tecnologías BiomédicasUniversidad de La LagunaLa LagunaSpain
| | - Diego M. Presman
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET‐Universidad de Buenos AiresFacultad de Ciencias Exactas y NaturalesBuenos AiresArgentina
| | - Gordon L. Hager
- Laboratory of Receptor Biology and Gene ExpressionNational Cancer Institute, National Institutes of HealthBethesdaMarylandUSA
| | - Diego Alvarez de la Rosa
- Laboratory of Receptor Biology and Gene ExpressionNational Cancer Institute, National Institutes of HealthBethesdaMarylandUSA
- Departmento de Ciencias Médicas Básicas and Instituto de Tecnologías BiomédicasUniversidad de La LagunaLa LagunaSpain
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13
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Johnson KA, Budicini MR, Bhattarai N, Sharma T, Urata S, Gerstman BS, Chapagain PP, Li S, Stahelin RV. PI(4,5)P 2 binding sites in the Ebola virus matrix protein VP40 modulate assembly and budding. J Lipid Res 2024; 65:100512. [PMID: 38295986 PMCID: PMC10909612 DOI: 10.1016/j.jlr.2024.100512] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 01/12/2024] [Accepted: 01/17/2024] [Indexed: 03/02/2024] Open
Abstract
Ebola virus (EBOV) causes severe hemorrhagic fever in humans and is lethal in a large percentage of those infected. The EBOV matrix protein viral protein 40 kDa (VP40) is a peripheral binding protein that forms a shell beneath the lipid bilayer in virions and virus-like particles (VLPs). VP40 is required for virus assembly and budding from the host cell plasma membrane. VP40 is a dimer that can rearrange into oligomers at the plasma membrane interface, but it is unclear how these structures form and how they are stabilized. We therefore investigated the ability of VP40 to form stable oligomers using in vitro and cellular assays. We characterized two lysine-rich regions in the VP40 C-terminal domain (CTD) that bind phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) and play distinct roles in lipid binding and the assembly of the EBOV matrix layer. The extensive analysis of VP40 with and without lipids by hydrogen deuterium exchange mass spectrometry revealed that VP40 oligomers become extremely stable when VP40 binds PI(4,5)P2. The PI(4,5)P2-induced stability of VP40 dimers and oligomers is a critical factor in VP40 oligomerization and release of VLPs from the plasma membrane. The two lysine-rich regions of the VP40 CTD have different roles with respect to interactions with plasma membrane phosphatidylserine (PS) and PI(4,5)P2. CTD region 1 (Lys221, Lys224, and Lys225) interacts with PI(4,5)P2 more favorably than PS and is important for VP40 extent of oligomerization. In contrast, region 2 (Lys270, Lys274, Lys275, and Lys279) mediates VP40 oligomer stability via lipid interactions and has a more prominent role in release of VLPs.
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Affiliation(s)
- Kristen A Johnson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, USA
| | - Melissa R Budicini
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, USA
| | - Nisha Bhattarai
- Department of Physics, Florida International University, Miami, FL, USA
| | - Tej Sharma
- Department of Physics, Florida International University, Miami, FL, USA
| | - Sarah Urata
- Department of Medicine, University of California San Diego, San Diego, CA, USA
| | - Bernard S Gerstman
- Department of Physics, Florida International University, Miami, FL, USA; Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
| | - Prem P Chapagain
- Department of Physics, Florida International University, Miami, FL, USA; Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
| | - Sheng Li
- Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
| | - Robert V Stahelin
- Department of Medicinal Chemistry and Molecular Pharmacology and the Purdue Institute of Inflammation, Immunology, and Infectious Disease, Purdue University, West Lafayette, IN, USA.
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14
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Mumford TR, Rae D, Brackhahn E, Idris A, Gonzalez-Martinez D, Pal AA, Chung MC, Guan J, Rhoades E, Bugaj LJ. Simple visualization of submicroscopic protein clusters with a phase-separation-based fluorescent reporter. Cell Syst 2024; 15:166-179.e7. [PMID: 38335954 PMCID: PMC10947474 DOI: 10.1016/j.cels.2024.01.005] [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: 08/22/2022] [Revised: 11/06/2023] [Accepted: 01/19/2024] [Indexed: 02/12/2024]
Abstract
Protein clustering plays numerous roles in cell physiology and disease. However, protein oligomers can be difficult to detect because they are often too small to appear as puncta in conventional fluorescence microscopy. Here, we describe a fluorescent reporter strategy that detects protein clusters with high sensitivity called CluMPS (clusters magnified by phase separation). A CluMPS reporter detects and visually amplifies even small clusters of a binding partner, generating large, quantifiable fluorescence condensates. We use computational modeling and optogenetic clustering to demonstrate that CluMPS can detect small oligomers and behaves rationally according to key system parameters. CluMPS detected small aggregates of pathological proteins where the corresponding GFP fusions appeared diffuse. CluMPS also detected and tracked clusters of unmodified and tagged endogenous proteins, and orthogonal CluMPS probes could be multiplexed in cells. CluMPS provides a powerful yet straightforward approach to observe higher-order protein assembly in its native cellular context. A record of this paper's transparent peer review process is included in the supplemental information.
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Affiliation(s)
- Thomas R Mumford
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Diarmid Rae
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Emily Brackhahn
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Abbas Idris
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Ayush Aditya Pal
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Michael C Chung
- Department of Physics, University of Florida, Gainesville, FL 32611, USA
| | - Juan Guan
- Department of Physics, University of Florida, Gainesville, FL 32611, USA; Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL 32611, USA
| | - Elizabeth Rhoades
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Lukasz J Bugaj
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute of Regenerative Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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15
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Royer CA, Tyers M, Tollis S. Absolute quantification of protein number and dynamics in single cells. Curr Opin Struct Biol 2023; 82:102673. [PMID: 37595512 DOI: 10.1016/j.sbi.2023.102673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 08/20/2023]
Abstract
Quantitative characterization of protein abundance and interactions in live cells is necessary to understand and predict cellular behavior. The accurate determination of copy number for individual proteins and heterologous complexes in individual cells is critical because small changes in protein dosage, often less than two-fold, can have strong phenotypic consequences. Here, we review the merits and pitfalls of different quantitative fluorescence imaging methods for single-cell determination of protein abundance, localization, interactions, and dynamics. In particular, we discuss how scanning number and brightness (sN&B) and its variation, Raster scanning image correlation spectroscopy (RICS), exploit stochastic noise in small measurement volumes to quantify protein abundance, stoichiometry, and dynamics with high accuracy.
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Affiliation(s)
- Catherine A Royer
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy NY 12180, USA.
| | - Mike Tyers
- Program in Molecular Medicine, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Sylvain Tollis
- Institute of Biomedicine, University of Eastern Finland, Kuopio 70210 Finland
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16
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Anaya EU, Amin AE, Wester MJ, Danielson ME, Michel KS, Neumann AK. Dectin-1 multimerization and signaling depends on fungal β-glucan structure and exposure. Biophys J 2023; 122:3749-3767. [PMID: 37515324 PMCID: PMC10541497 DOI: 10.1016/j.bpj.2023.07.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 06/30/2023] [Accepted: 07/25/2023] [Indexed: 07/30/2023] Open
Abstract
Dectin-1A is a C-type lectin innate immunoreceptor that recognizes β-(1,3;1,6)-glucan, a structural component of Candida species cell walls. β-Glucans can adopt solution structures ranging from random coil to insoluble fiber due to tertiary (helical) and quaternary structure. Fungal β-glucans of medium and high molecular weight are highly structured, but low molecular weight glucan is much less structured. Despite similar affinity for Dectin-1, the ability of glucans to induce Dectin-1A-mediated signaling correlates with degree of structure. Glucan denaturation experiments showed that glucan structure determines agonistic potential, but not receptor binding affinity. We explored the impact of glucan structure on molecular aggregation of Dectin-1A. Stimulation with glucan signaling decreased Dectin-1A diffusion coefficient. Fluorescence measurements provided direct evidence of ligation-induced Dectin-1A aggregation, which positively correlated with increasing glucan structure content. In contrast, Dectin-1A is predominantly in a low aggregation state in resting cells. Molecular aggregates formed during interaction with highly structured, agonistic glucans did not exceed relatively small (<15 nm) clusters of a few engaged receptors. Finally, we observed increased molecular aggregation of Dectin-1A at fungal particle contact sites in a manner that positively correlated with the degree of exposed glucan on the particle surface. These results indicate that Dectin-1A senses the solution conformation of β-glucans through their varying ability to drive receptor dimer/oligomer formation and activation of membrane proximal signaling events.
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Affiliation(s)
- Eduardo U Anaya
- Department of Pathology, University of New Mexico, School of Medicine, Albuquerque, New Mexico
| | - Akram Etemadi Amin
- Department of Pathology, University of New Mexico, School of Medicine, Albuquerque, New Mexico; Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico
| | - Michael J Wester
- Department of Mathematics and Statistics, University of New Mexico, Albuquerque, New Mexico
| | | | | | - Aaron K Neumann
- Department of Pathology, University of New Mexico, School of Medicine, Albuquerque, New Mexico.
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17
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Petrich A, Aji AK, Dunsing V, Chiantia S. Benchmarking of novel green fluorescent proteins for the quantification of protein oligomerization in living cells. PLoS One 2023; 18:e0285486. [PMID: 37535571 PMCID: PMC10399874 DOI: 10.1371/journal.pone.0285486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 04/25/2023] [Indexed: 08/05/2023] Open
Abstract
Protein-protein-interactions play an important role in many cellular functions. Quantitative non-invasive techniques are applied in living cells to evaluate such interactions, thereby providing a broader understanding of complex biological processes. Fluorescence fluctuation spectroscopy describes a group of quantitative microscopy approaches for the characterization of molecular interactions at single cell resolution. Through the obtained molecular brightness, it is possible to determine the oligomeric state of proteins. This is usually achieved by fusing fluorescent proteins (FPs) to the protein of interest. Recently, the number of novel green FPs has increased, with consequent improvements to the quality of fluctuation-based measurements. The photophysical behavior of FPs is influenced by multiple factors (including photobleaching, protonation-induced "blinking" and long-lived dark states). Assessing these factors is critical for selecting the appropriate fluorescent tag for live cell imaging applications. In this work, we focus on novel green FPs that are extensively used in live cell imaging. A systematic performance comparison of several green FPs in living cells under different pH conditions using Number & Brightness (N&B) analysis and scanning fluorescence correlation spectroscopy was performed. Our results show that the new FP Gamillus exhibits higher brightness at the cost of lower photostability and fluorescence probability (pf), especially at lower pH. mGreenLantern, on the other hand, thanks to a very high pf, is best suited for multimerization quantification at neutral pH. At lower pH, mEGFP remains apparently the best choice for multimerization investigation. These guidelines provide the information needed to plan quantitative fluorescence microscopy involving these FPs, both for general imaging or for protein-protein-interactions quantification via fluorescence fluctuation-based methods.
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Affiliation(s)
- Annett Petrich
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
| | - Amit Koikkarah Aji
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
| | - Valentin Dunsing
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
- Aix-Marseille University, CNRS, UMR 7288, IBDM, Turing Center for Living Systems, Marseille, France
| | - Salvatore Chiantia
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
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18
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Sankaran J, Wohland T. Current capabilities and future perspectives of FCS: super-resolution microscopy, machine learning, and in vivo applications. Commun Biol 2023; 6:699. [PMID: 37419967 PMCID: PMC10328937 DOI: 10.1038/s42003-023-05069-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 06/23/2023] [Indexed: 07/09/2023] Open
Abstract
Fluorescence correlation spectroscopy (FCS) is a single molecule sensitive tool for the quantitative measurement of biomolecular dynamics and interactions. Improvements in biology, computation, and detection technology enable real-time FCS experiments with multiplexed detection even in vivo. These new imaging modalities of FCS generate data at the rate of hundreds of MB/s requiring efficient data processing tools to extract information. Here, we briefly review FCS's capabilities and limitations before discussing recent directions that address these limitations with a focus on imaging modalities of FCS, their combinations with super-resolution microscopy, new evaluation strategies, especially machine learning, and applications in vivo.
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Affiliation(s)
- Jagadish Sankaran
- Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore, 138632, Singapore.
| | - Thorsten Wohland
- Department of Biological Sciences, National University of Singapore, Singapore, 117558, Singapore.
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19
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Martin‐Fernandez ML. A perspective of fluorescence microscopy for cellular structural biology with EGFR as witness. J Microsc 2023; 291:73-91. [PMID: 36282005 PMCID: PMC10952613 DOI: 10.1111/jmi.13151] [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: 09/20/2022] [Revised: 09/20/2022] [Accepted: 10/11/2022] [Indexed: 10/31/2022]
Abstract
The epidermal growth factor receptor (EGFR) is a poster child for the understanding of receptor behaviour, and of paramount importance to cell function and human health. Cloned almost forty years ago, the interest in EGFR's structure/function relationships remains unabated, not least because changes in oncogenic EGFR mutants are key drivers of the formation of lung and brain tumours. The structure of the assemblies formed by EGFR have been comprehensibly investigated by techniques such as high-resolution X-ray crystallography, NMR and all-atom molecular dynamics (MD) simulations. However, the complexity embedded in the portfolio of EGFR states that are only possible in the physiological environment of cells has often proved refractory to cell-free structural methods. Conversely, some key inroads made by quantitative fluorescence microscopy and super-resolution have depended on exploiting the wealth of structures available. Here, a brief personal perspective is provided on how quantitative fluorescence microscopy and super-resolution methods have cross-fertilised with cell-free-derived EGFR structural information. I primarily discuss areas in which my research group has made a contribution to fill gaps in EGFR's cellular structural biology and towards developing new tools to investigate macromolecular assemblies in cells.
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Affiliation(s)
- M. L. Martin‐Fernandez
- Central Laser FacilityScience and Technology Facilities Council, Rutherford Appleton LaboratoryDidcotUK
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20
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Fettweis G, Johnson TA, Almeida-Prieto B, Presman DM, Hager GL, Alvarez de la Rosa D. The mineralocorticoid receptor forms higher order oligomers upon DNA binding. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.26.525752. [PMID: 36789424 PMCID: PMC9928021 DOI: 10.1101/2023.01.26.525752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The prevailing model of steroid hormone nuclear receptor function assumes ligand-induced homodimer formation followed by binding to DNA hormone response elements (HREs). This model has been challenged by evidence showing that the glucocorticoid receptor (GR) forms tetramers upon ligand and DNA binding, which then drive receptor-mediated gene transactivation and transrepression. GR and the closely-related mineralocorticoid receptors (MR) interact to transduce corticosteroid hormone signaling, but whether they share the same quaternary arrangement is unknown. Here, we used a fluorescence imaging technique, Number & Brightness, to study oligomerization in a cell system allowing real-time analysis of receptor-DNA interactions. Agonist-bound MR forms tetramers in the nucleoplasm and higher order oligomers upon binding to HREs. Antagonists form intermediate quaternary arrangements, suggesting that large oligomers are essential for function. Divergence between MR and GR quaternary structure is driven by different functionality of known and new multimerization interfaces, which does not preclude formation of heteromers. Thus, influencing oligomerization may be important to selectively modulate corticosteroid signaling.
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Affiliation(s)
- Gregory Fettweis
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-5055, USA
| | - Thomas A. Johnson
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-5055, USA
| | - Brian Almeida-Prieto
- Departmento de Ciencias Médicas Básicas and Instituto de Tecnologías Biomédicas, Universidad de La Laguna, La Laguna 38200, Spain
| | - Diego M. Presman
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires C1428EGA, Argentina
| | - Gordon L. Hager
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-5055, USA
| | - Diego Alvarez de la Rosa
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-5055, USA
- Departmento de Ciencias Médicas Básicas and Instituto de Tecnologías Biomédicas, Universidad de La Laguna, La Laguna 38200, Spain
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21
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van Zanten TS, S GP, Mayor S. Quantitative fluorescence emission anisotropy microscopy for implementing homo-fluorescence resonance energy transfer measurements in living cells. Mol Biol Cell 2023; 34:tp1. [PMID: 37144969 DOI: 10.1091/mbc.e22-09-0446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023] Open
Abstract
Quantitative fluorescence emission anisotropy microscopy reveals the organization of fluorescently labeled cellular components and allows their characterization in terms of changes in either rotational diffusion or homo-Förster's energy transfer characteristics in living cells. These properties provide insights into molecular organization, such as orientation, confinement, and oligomerization in situ. Here we elucidate how quantitative measurements of anisotropy using multiple microscope systems may be made by bringing out the main parameters that influence the quantification of fluorescence emission anisotropy. We focus on a variety of parameters that contribute to errors associated with the measurement of emission anisotropy in a microscope. These include the requirement for adequate photon counts for the necessary discrimination of anisotropy values, the influence of extinction ratios of the illumination source, the detector system, the role of numerical aperture, and excitation wavelength. All these parameters also affect the ability to capture the dynamic range of emission anisotropy necessary for quantifying its reduction due to homo-FRET and other processes. Finally, we provide easily implementable tests to assess whether homo-FRET is a cause for the observed emission depolarization.
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Affiliation(s)
- Thomas S van Zanten
- Cell Biology Group, National Centre for Biological Sciences, UAS-GKVK Campus, Tata Institute for Fundamental Research, Bangalore 560065, India
| | - Greeshma Pradeep S
- Cell Biology Group, National Centre for Biological Sciences, UAS-GKVK Campus, Tata Institute for Fundamental Research, Bangalore 560065, India
| | - Satyajit Mayor
- Cell Biology Group, National Centre for Biological Sciences, UAS-GKVK Campus, Tata Institute for Fundamental Research, Bangalore 560065, India
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22
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Padilla-Parra S. Time-resolved single virus tracking and spectral imaging to understand HIV-1 entry and fusion. Biol Cell 2023; 115:e2200082. [PMID: 36440600 DOI: 10.1111/boc.202200082] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Revised: 11/02/2022] [Accepted: 11/18/2022] [Indexed: 11/29/2022]
Abstract
Single Virus Tracking (SVT) is a key technique to understand how individual viral particles evolve during the infection cycle. In the case of the human immunodeficiency virus (HIV-1), this technology, which can be employed using a simple and affordable wide-field microscope, has proven to be very useful in the first steps of infection, such as the kinetics of the fusion reaction or the point of fusion within live cells. Here, we describe how SVT in combination with other spectral imaging approaches is a powerful technique to illuminate crucial mechanistic aspects of the HIV-1 fusion reaction. We also stress the role of our laboratory in elucidating a few mechanistic aspects of retroviral fusion employing SVT such as: (i) the role of dynamin, (ii) how metabolism modulates membrane composition and cholesterol and its impact in fusion, (iii) the importance of envelope glycoprotein (Env) intra- and inter-molecular dynamics for neutralization, or (iv) the time-resolved fusion stoichiometry in three characteristic steps for the HIV-1 prefusion step. These observations constitute a good testimony of the complexity of retroviral fusion and show the strength of SVT when applied to live cells and combined with quantitative spectral approaches. Finally, we propose several crucial remaining questions around HIV-1 fusion and how the combined use of these technologies, always in live cells, will be able to shed light into the intricacies of arguably the most important step of the HIV-1 infection cycle.
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Affiliation(s)
- Sergi Padilla-Parra
- Faculty of Life Sciences & Medicine, Department of Infectious Diseases, King's College London, London, UK.,Randall Division of Cell and Molecular Biophysics, King's College London, London, UK
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23
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He H, Qin G, Bi S, Feng Z, Mao J, Guan X, Xue M, Wang Z, Wang X, Yu D, Huang F. Deep-Learning-Enhanced Diffusion Imaging Assay for Resolving Local-Density Effects on Membrane Receptors. Anal Chem 2023; 95:3300-3308. [PMID: 36716433 DOI: 10.1021/acs.analchem.2c04326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
G-protein-coupled receptor (GPCR) density at the cell surface is thought to regulate receptor function. Spatially resolved measurements of local-density effects on GPCRs are needed but technically limited by density heterogeneity and mobility of membrane receptors. We now develop a deep-learning (DL)-enhanced diffusion imaging assay that can measure local-density effects on ligand-receptor interactions in the plasma membrane of live cells. In this method, the DL algorithm allows the transformation of 100 ms exposure images to density maps that report receptor numbers over any specified region with ∼95% accuracy by 1 s exposure images as ground truth. With the density maps, a diffusion assay is further established for spatially resolved measurements of receptor diffusion coefficient as well as to express relationships between receptor diffusivity and local density. By this assay, we scrutinize local-density effects on chemokine receptor CXCR4 interactions with various ligands, which reveals that an agonist prefers to act with CXCR4 at low density while an inverse agonist dominates at high density. This work suggests a new insight into density-dependent receptor regulation as well as provides an unprecedented assay that can be applicable to a wide variety of receptors in live cells.
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Affiliation(s)
- Hua He
- State Key Laboratory of Heavy Oil Processing and College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao266580, China
| | - Guangyong Qin
- State Key Laboratory of Heavy Oil Processing and College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao266580, China
| | - Simin Bi
- State Key Laboratory of Heavy Oil Processing and College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao266580, China
| | - Zhenzhen Feng
- Technical Center of Qingdao Customs District, Qingdao266500, China
| | - Jian Mao
- State Key Laboratory of Heavy Oil Processing and College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao266580, China
| | - Xin Guan
- State Key Laboratory of Heavy Oil Processing and College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao266580, China
| | - Minmin Xue
- State Key Laboratory of Heavy Oil Processing and College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao266580, China
| | - Zhirui Wang
- State Key Laboratory of Heavy Oil Processing and College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao266580, China
| | - Xiaojuan Wang
- State Key Laboratory of Heavy Oil Processing and College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao266580, China
| | - Daoyong Yu
- State Key Laboratory of Heavy Oil Processing and College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao266580, China
| | - Fang Huang
- State Key Laboratory of Heavy Oil Processing and College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao266580, China
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24
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Chiang HJ, Koo DES, Kitano M, Burkitt S, Unruh JR, Zavaleta C, Trinh LA, Fraser SE, Cutrale F. HyU: Hybrid Unmixing for longitudinal in vivo imaging of low signal-to-noise fluorescence. Nat Methods 2023; 20:248-258. [PMID: 36658278 PMCID: PMC9911352 DOI: 10.1038/s41592-022-01751-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 12/13/2022] [Indexed: 01/21/2023]
Abstract
The expansion of fluorescence bioimaging toward more complex systems and geometries requires analytical tools capable of spanning widely varying timescales and length scales, cleanly separating multiple fluorescent labels and distinguishing these labels from background autofluorescence. Here we meet these challenging objectives for multispectral fluorescence microscopy, combining hyperspectral phasors and linear unmixing to create Hybrid Unmixing (HyU). HyU is efficient and robust, capable of quantitative signal separation even at low illumination levels. In dynamic imaging of developing zebrafish embryos and in mouse tissue, HyU was able to cleanly and efficiently unmix multiple fluorescent labels, even in demanding volumetric timelapse imaging settings. HyU permits high dynamic range imaging, allowing simultaneous imaging of bright exogenous labels and dim endogenous labels. This enables coincident studies of tagged components, cellular behaviors and cellular metabolism within the same specimen, providing more accurate insights into the orchestrated complexity of biological systems.
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Affiliation(s)
- Hsiao Ju Chiang
- Translational Imaging Center, University of Southern California, Los Angeles, CA, USA
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Daniel E S Koo
- Translational Imaging Center, University of Southern California, Los Angeles, CA, USA
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Masahiro Kitano
- Translational Imaging Center, University of Southern California, Los Angeles, CA, USA
- Molecular and Computational Biology, University of Southern California, Los Angeles, CA, USA
| | - Sean Burkitt
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Jay R Unruh
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Cristina Zavaleta
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Le A Trinh
- Translational Imaging Center, University of Southern California, Los Angeles, CA, USA
- Molecular and Computational Biology, University of Southern California, Los Angeles, CA, USA
| | - Scott E Fraser
- Translational Imaging Center, University of Southern California, Los Angeles, CA, USA
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
- Molecular and Computational Biology, University of Southern California, Los Angeles, CA, USA
| | - Francesco Cutrale
- Translational Imaging Center, University of Southern California, Los Angeles, CA, USA.
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA.
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25
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Menke L, Sperber HS, Aji AK, Chiantia S, Schwarzer R, Sieben C. Advances in fluorescence microscopy for orthohantavirus research. Microscopy (Oxf) 2023:6987530. [PMID: 36639937 DOI: 10.1093/jmicro/dfac075] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 11/30/2022] [Accepted: 01/12/2023] [Indexed: 01/15/2023] Open
Abstract
Orthohantaviruses are important zoonotic pathogens responsible for a considerable disease burden globally. Partly due to our incomplete understanding of orthohantavirus replication, there is currently no effective antiviral treatment available. Recently, novel microscopy techniques and cutting-edge, automated image analysis algorithms have emerged, enabling to study cellular, subcellular and even molecular processes in unprecedented detail and depth. To date, fluorescence light microscopy allows us to visualize viral and cellular components and macromolecular complexes in live cells which in turn enables the study of specific steps of the viral replication cycle such as particle entry or protein trafficking at high temporal and spatial resolution. In this review, we highlight how fluorescence microscopy has provided new insights and improved our understanding of orthohantavirus biology. We discuss technical challenges such as studying live infected cells, give alternatives with recombinant protein expression and highlight future opportunities for example the application of super-resolution microscopy techniques, which has shown great potential in studies of different cellular processes and viral pathogens.
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Affiliation(s)
- Laura Menke
- Nanoscale Infection Biology Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Hannah S Sperber
- Institute for Translational HIV Research, University Hospital Essen, Essen, Germany
| | - Amit Koikkarah Aji
- University of Potsdam, Institute of Biochemistry and Biology, Department of Physical Biochemistry, Potsdam, Germany
| | - Salvatore Chiantia
- University of Potsdam, Institute of Biochemistry and Biology, Department of Physical Biochemistry, Potsdam, Germany
| | - Roland Schwarzer
- Institute for Translational HIV Research, University Hospital Essen, Essen, Germany
| | - Christian Sieben
- Nanoscale Infection Biology Helmholtz Centre for Infection Research, Braunschweig, Germany.,Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
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26
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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: 0] [Impact Index Per Article: 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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27
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Scharrig E, Sanmillan ML, Giraudo CG. Analysis of immune synapses by τau-STED imaging and 3D-quantitative colocalization of lytic granule markers. Methods Cell Biol 2023. [DOI: 10.1016/bs.mcb.2023.01.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
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28
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Balasubramanian H, Sankaran J, Pandey S, Goh CJH, Wohland T. The dependence of EGFR oligomerization on environment and structure: A camera-based N&B study. Biophys J 2022; 121:4452-4466. [PMID: 36335429 PMCID: PMC9748371 DOI: 10.1016/j.bpj.2022.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 09/30/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022] Open
Abstract
Number and brightness (N&B) analysis is a fluorescence spectroscopy technique to quantify oligomerization of the mobile fraction of proteins. Accurate results, however, rely on a good knowledge of nonfluorescent states of the fluorescent labels, especially of fluorescent proteins, which are widely used in biology. Fluorescent proteins have been characterized for confocal, but not camera-based, N&B, which allows, in principle, faster measurements over larger areas. Here, we calibrate camera-based N&B implemented on a total internal reflection fluorescence microscope for various fluorescent proteins by determining their propensity to be fluorescent. We then apply camera-based N&B in live CHO-K1 cells to determine the oligomerization state of the epidermal growth factor receptor (EGFR), a transmembrane receptor tyrosine kinase that is a crucial regulator of cell proliferation and survival with implications in many cancers. EGFR oligomerization in resting cells and its regulation by the plasma membrane microenvironment are still under debate. Therefore, we investigate the effects of extrinsic factors, including membrane organization, cytoskeletal structure, and ligand stimulation, and intrinsic factors, including mutations in various EGFR domains, on the receptor's oligomerization. Our results demonstrate that EGFR oligomerization increases with removal of cholesterol or sphingolipids or the disruption of GM3-EGFR interactions, indicating raft association. However, oligomerization is not significantly influenced by the cytoskeleton. Mutations in either I706/V948 residues or E685/E687/E690 residues in the kinase and juxtamembrane domains, respectively, lead to a decrease in oligomerization, indicating their necessity for EGFR dimerization. Finally, EGFR phosphorylation is oligomerization dependent, involving the extracellular domain (550-580 residues). Coupled with biochemical investigations, camera-based N&B indicates that EGFR oligomerization and phosphorylation are the outcomes of several molecular interactions involving the lipid content and structure of the cell membrane and multiple residues in the kinase, juxtamembrane, and extracellular domains.
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Affiliation(s)
- Harikrushnan Balasubramanian
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Jagadish Sankaran
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Shambhavi Pandey
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Corinna Jie Hui Goh
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Thorsten Wohland
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore; Department of Chemistry, National University of Singapore, Singapore, Singapore.
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29
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Jiménez-Panizo A, Alegre-Martí A, Tettey T, Fettweis G, Abella M, Antón R, Johnson T, Kim S, Schiltz R, Núñez-Barrios I, Font-Díaz J, Caelles C, Valledor A, Pérez P, Rojas A, Fernández-Recio J, Presman D, Hager G, Fuentes-Prior P, Estébanez-Perpiñá E. The multivalency of the glucocorticoid receptor ligand-binding domain explains its manifold physiological activities. Nucleic Acids Res 2022; 50:13063-13082. [PMID: 36464162 PMCID: PMC9825158 DOI: 10.1093/nar/gkac1119] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 10/28/2022] [Accepted: 11/08/2022] [Indexed: 12/05/2022] Open
Abstract
The glucocorticoid receptor (GR) is a ubiquitously expressed transcription factor that controls metabolic and homeostatic processes essential for life. Although numerous crystal structures of the GR ligand-binding domain (GR-LBD) have been reported, the functional oligomeric state of the full-length receptor, which is essential for its transcriptional activity, remains disputed. Here we present five new crystal structures of agonist-bound GR-LBD, along with a thorough analysis of previous structural work. We identify four distinct homodimerization interfaces on the GR-LBD surface, which can associate into 20 topologically different homodimers. Biologically relevant homodimers were identified by studying a battery of GR point mutants including crosslinking assays in solution, quantitative fluorescence microscopy in living cells, and transcriptomic analyses. Our results highlight the relevance of non-canonical dimerization modes for GR, especially of contacts made by loop L1-3 residues such as Tyr545. Our work illustrates the unique flexibility of GR's LBD and suggests different dimeric conformations within cells. In addition, we unveil pathophysiologically relevant quaternary assemblies of the receptor with important implications for glucocorticoid action and drug design.
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Affiliation(s)
| | | | | | - Gregory Fettweis
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-5055, USA
| | - Montserrat Abella
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona (UB), 08028 Barcelona, Spain,Institute of Biomedicine of the University of Barcelona (IBUB), University of Barcelona (UB), 08028 Barcelona, Spain
| | - Rosa Antón
- Biomedical Research Institute Sant Pau (IIB Sant Pau), 08041 Barcelona, Spain
| | - Thomas A Johnson
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-5055, USA
| | - Sohyoung Kim
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-5055, USA
| | - R Louis Schiltz
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-5055, USA
| | - Israel Núñez-Barrios
- Andalusian Center for Developmental Biology (CABD-CSIC). Campus Universitario Pablo de Olavide, 41013 Sevilla, Spain
| | - Joan Font-Díaz
- Institute of Biomedicine of the University of Barcelona (IBUB), University of Barcelona (UB), 08028 Barcelona, Spain,Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain
| | - Carme Caelles
- Institute of Biomedicine of the University of Barcelona (IBUB), University of Barcelona (UB), 08028 Barcelona, Spain,Department of Biochemistry and Physiology, Faculty of Pharmacy and Food Sciences, University of Barcelona, Barcelona 08028, Spain
| | - Annabel F Valledor
- Institute of Biomedicine of the University of Barcelona (IBUB), University of Barcelona (UB), 08028 Barcelona, Spain,Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain
| | - Paloma Pérez
- Instituto de Biomedicina de Valencia (IBV)-CSIC, 46010, Valencia, Spain
| | - Ana M Rojas
- Andalusian Center for Developmental Biology (CABD-CSIC). Campus Universitario Pablo de Olavide, 41013 Sevilla, Spain
| | - Juan Fernández-Recio
- Instituto de Ciencias de la Vid y del Vino (ICVV), CSIC - Universidad de La Rioja - Gobierno de La Rioja, 26007 Logroño, Spain
| | - Diego M Presman
- IFIBYNE, UBA-CONICET, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires C1428EGA, Argentina
| | - Gordon L Hager
- Correspondence may also be addressed to Gordon L. Hager. Tel: +1 240 760 6618;
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30
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Russo L, Giacomelli C, Fortino M, Marzo T, Ferri G, Calvello M, Viegi A, Magrì A, Pratesi A, Pietropaolo A, Cardarelli F, Martini C, Rizzarelli E, Marchetti L, La Mendola D, Trincavelli ML. Neurotrophic Activity and Its Modulation by Zinc Ion of a Dimeric Peptide Mimicking the Brain-Derived Neurotrophic Factor N-Terminal Region. ACS Chem Neurosci 2022; 13:3453-3463. [PMID: 36346920 PMCID: PMC9732821 DOI: 10.1021/acschemneuro.2c00463] [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] [Indexed: 11/09/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) is a neurotrophin (NT) essential for neuronal development and synaptic plasticity. Dysregulation of BDNF signaling is implicated in different neurological disorders. The direct NT administration as therapeutics has revealed to be challenging. This has prompted the design of peptides mimicking different regions of the BDNF structure. Although loops 2 and 4 have been thoroughly investigated, less is known regarding the BDNF N-terminal region, which is involved in the selective recognition of the TrkB receptor. Herein, a dimeric form of the linear peptide encompassing the 1-12 residues of the BDNF N-terminal (d-bdnf) was synthesized. It demonstrated to act as an agonist promoting specific phosphorylation of TrkB and downstream ERK and AKT effectors. The ability to promote TrkB dimerization was investigated by advanced fluorescence microscopy and molecular dynamics (MD) simulations, finding activation modes shared with BDNF. Furthermore, d-bdnf was able to sustain neurite outgrowth and increase the expression of differentiation (NEFM, LAMC1) and polarization markers (MAP2, MAPT) demonstrating its neurotrophic activity. As TrkB activity is affected by zinc ions in the synaptic cleft, we first verified the ability of d-bdnf to coordinate zinc and then the effect of such complexation on its activity. The d-bdnf neurotrophic activity was reduced by zinc complexation, demonstrating the role of the latter in tuning the activity of the new peptido-mimetic. Taken together our data uncover the neurotrophic properties of a novel BDNF mimetic peptide and pave the way for future studies to understand the pharmacological basis of d-bdnf action and develop novel BDNF-based therapeutic strategies.
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Affiliation(s)
- Lara Russo
- Dipartimento
di Farmacia, Università di Pisa, Pisa 56127, Italy
| | | | | | - Tiziano Marzo
- Dipartimento
di Farmacia, Università di Pisa, Pisa 56127, Italy
| | - Gianmarco Ferri
- Laboratorio
NEST, Scuola Normale Superiore, Pisa 56127, Italy
| | | | | | - Antonio Magrì
- Istituto
di Cristallografia, Consiglio Nazionale delle Ricerche (CNR), Catania 95126, Italy
| | - Alessandro Pratesi
- Dipartimento
di Chimica e Chimica Industriale, Università
di Pisa, Pisa 56124, Italy
| | | | | | - Claudia Martini
- Dipartimento
di Farmacia, Università di Pisa, Pisa 56127, Italy
| | - Enrico Rizzarelli
- Istituto
di Cristallografia, Consiglio Nazionale delle Ricerche (CNR), Catania 95126, Italy,Università
degli Studi di Catania, Catania 95124, Italy
| | - Laura Marchetti
- Dipartimento
di Farmacia, Università di Pisa, Pisa 56127, Italy,
| | - Diego La Mendola
- Dipartimento
di Farmacia, Università di Pisa, Pisa 56127, Italy,
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31
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Husby ML, Amiar S, Prugar LI, David EA, Plescia CB, Huie KE, Brannan JM, Dye JM, Pienaar E, Stahelin RV. Phosphatidylserine clustering by the Ebola virus matrix protein is a critical step in viral budding. EMBO Rep 2022; 23:e51709. [PMID: 36094794 PMCID: PMC9638875 DOI: 10.15252/embr.202051709] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 08/16/2022] [Accepted: 08/19/2022] [Indexed: 07/28/2023] Open
Abstract
Phosphatidylserine (PS) is a critical lipid factor in the assembly and spread of numerous lipid-enveloped viruses. Here, we describe the ability of the Ebola virus (EBOV) matrix protein eVP40 to induce clustering of PS and promote viral budding in vitro, as well as the ability of an FDA-approved drug, fendiline, to reduce PS clustering and subsequent virus budding and entry. To gain mechanistic insight into fendiline inhibition of EBOV replication, multiple in vitro assays were run including imaging, viral budding and viral entry assays. Fendiline lowers PS content in mammalian cells and PS in the plasma membrane, where the ability of VP40 to form new virus particles is greatly lower. Further, particles that form from fendiline-treated cells have altered particle morphology and cannot significantly infect/enter cells. These complementary studies reveal the mechanism by which EBOV matrix protein clusters PS to enhance viral assembly, budding, and spread from the host cell while also laying the groundwork for fundamental drug targeting strategies.
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Affiliation(s)
- Monica L Husby
- Department of Medicinal Chemistry & Molecular PharmacologyPurdue UniversityWest LafayetteINUSA
- Purdue Institute of Inflammation, Immunology and Infectious Disease (PI4D)Purdue University, West LafayetteWest LafayetteINUSA
| | - Souad Amiar
- Department of Medicinal Chemistry & Molecular PharmacologyPurdue UniversityWest LafayetteINUSA
- Purdue Institute of Inflammation, Immunology and Infectious Disease (PI4D)Purdue University, West LafayetteWest LafayetteINUSA
| | - Laura I Prugar
- United States Army Medical Research Institute of Infectious Diseases USAMRIIDFort DetrickFrederickMDUSA
| | - Emily A David
- Department of Medicinal Chemistry & Molecular PharmacologyPurdue UniversityWest LafayetteINUSA
| | - Caroline B Plescia
- Department of Medicinal Chemistry & Molecular PharmacologyPurdue UniversityWest LafayetteINUSA
| | - Kathleen E Huie
- United States Army Medical Research Institute of Infectious Diseases USAMRIIDFort DetrickFrederickMDUSA
| | - Jennifer M Brannan
- United States Army Medical Research Institute of Infectious Diseases USAMRIIDFort DetrickFrederickMDUSA
| | - John M Dye
- United States Army Medical Research Institute of Infectious Diseases USAMRIIDFort DetrickFrederickMDUSA
| | - Elsje Pienaar
- Purdue Institute of Inflammation, Immunology and Infectious Disease (PI4D)Purdue University, West LafayetteWest LafayetteINUSA
- Weldon School of Biomedical EngineeringPurdue UniversityWest LafayetteINUSA
| | - Robert V Stahelin
- Department of Medicinal Chemistry & Molecular PharmacologyPurdue UniversityWest LafayetteINUSA
- Purdue Institute of Inflammation, Immunology and Infectious Disease (PI4D)Purdue University, West LafayetteWest LafayetteINUSA
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32
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Zapata-Mercado E, Biener G, McKenzie DM, Wimley WC, Pasquale EB, Raicu V, Hristova K. The efficacy of receptor tyrosine kinase EphA2 autophosphorylation increases with EphA2 oligomer size. J Biol Chem 2022; 298:102370. [PMID: 35970390 PMCID: PMC9512837 DOI: 10.1016/j.jbc.2022.102370] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 08/09/2022] [Accepted: 08/10/2022] [Indexed: 11/30/2022] Open
Abstract
The receptor tyrosine kinase (RTK) EphA2 is expressed in epithelial and endothelial cells and controls the assembly of cell-cell junctions. EphA2 has also been implicated in many diseases, including cancer. Unlike most RTKs, which signal predominantly as dimers, EphA2 readily forms high-order oligomers upon ligand binding. Here, we investigated if a correlation exists between EphA2 signaling properties and the size of the EphA2 oligomers induced by multiple ligands, including the widely used ephrinA1-Fc ligand, the soluble monomeric m-ephrinA1, and novel engineered peptide ligands. We used fluorescence intensity fluctuation (FIF) spectrometry to characterize the EphA2 oligomer populations induced by the different ligands. Interestingly, we found that different monomeric and dimeric ligands induce EphA2 oligomers with widely different size distributions. Our comparison of FIF brightness distribution parameters and EphA2 signaling parameters reveals that the efficacy of EphA2 phosphorylation on tyrosine 588, an autophosphorylation response contributing to EphA2 activation, correlates with EphA2 mean oligomer size. However, we found that other characteristics, such as the efficacy of AKT inhibition and ligand bias coefficients, appear to be independent of EphA2 oligomer size. Taken together, this work highlights the utility of FIF in RTK signaling research and demonstrates a quantitative correlation between the architecture of EphA2 signaling complexes and signaling features.
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Affiliation(s)
- Elmer Zapata-Mercado
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Gabriel Biener
- Department of Physics, University of Wisconsin, Milwaukee, Wisconsin, USA
| | - Daniel M McKenzie
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - William C Wimley
- Tulane University School of Medicine, Department of Biochemistry and Molecular Biology, New Orleans, Louisiana, USA
| | - Elena B Pasquale
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA.
| | - Valerica Raicu
- Department of Physics, University of Wisconsin, Milwaukee, Wisconsin, USA; Department of Biological Sciences, University of Wisconsin, Milwaukee, Wisconsin, USA.
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, USA.
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33
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Live Cell Fluorescence Imaging Shows Neurotransmitter Activation Promotes Aggregation of the Intracellular Domain of Amyloid Precursor Protein. J Membr Biol 2022; 255:613-622. [PMID: 36066615 DOI: 10.1007/s00232-022-00266-6] [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: 05/13/2022] [Accepted: 08/13/2022] [Indexed: 10/14/2022]
Abstract
Amyloid precursor protein (APP) is a major contributor to the pathology of Alzheimer's and other neurodegenerative diseases through the accumulation of extracellular plaques. Here, we have studied changes in APP translation and aggregation of the APP intracellular domain when the Gαq/PLCβ signaling system is activated by neurotransmitters. Using RT-PCR and a molecular beacon that follows APP mRNA in live cells, we find that Gαq activation sequesters APP mRNA similar to the stress granule response found in heat shock and hypo-osmotic shock thereby shutting down the production of APP. Following the intracellular domain of eGFP-APP, we find that Gαq stimulation increases aggregation as followed by number and brightness (N&B) analysis of single molecule fluorescence time series. Additionally, we show that APP aggregation is affected by changes in the levels of PLCβ1 and its cytosolic binding partners. Our studies show the neurotransmitter activation of Gαq/PLCβ reduces translation of APP and increases aggregation of its intracellular domain. These studies better establish a link between APP production and complexation and Gαq stimulation.
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34
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Wirth D, Paul MD, Pasquale EB, Hristova K. Direct quantification of ligand-induced lipid and protein microdomains with distinctive signaling properties. CHEMSYSTEMSCHEM 2022; 4:e202200011. [PMID: 36337751 PMCID: PMC9634703 DOI: 10.1002/syst.202200011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Indexed: 11/08/2022]
Abstract
Lipid rafts are ordered lipid domains that are enriched in saturated lipids, such as the ganglioside GM1. While lipid rafts are believed to exist in cells and to serve as signaling platforms through their enrichment in signaling components, they have not been directly observed in the plasma membrane without treatments that artificially cluster GM1 into large lattices. Here, we report that microscopic GM1-enriched domains can form, in the plasma membrane of live mammalian cells expressing the EphA2 receptor tyrosine kinase in response to its ligand ephrinA1-Fc. The GM1-enriched microdomains form concomitantly with EphA2-enriched microdomains. To gain insight into how plasma membrane heterogeneity controls signaling, we quantify the degree of EphA2 segregation and study initial EphA2 signaling steps in both EphA2-enriched and EphA2-depleted domains. By measuring dissociation constants, we demonstrate that the propensity of EphA2 to oligomerize is similar in EphA2-enriched and -depleted domains. However, surprisingly, EphA2 interacts preferentially with its downstream effector SRC in EphA2-depleted domains. The ability to induce microscopic GM1-enriched domains in live cells using a ligand for a transmembrane receptor will give us unprecedented opportunities to study the biophysical chemistry of lipid rafts.
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Affiliation(s)
- Daniel Wirth
- Department of Materials Science and Engineering, Johns Hopkins University, 3400 Charles Street, Baltimore, MD 21218
| | - Michael D. Paul
- Program in Molecular Biophysics, Johns Hopkins University, 3400 Charles Street, Baltimore, MD 21218
| | - Elena B. Pasquale
- Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Road, La Jolla, CA 92037
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, 3400 Charles Street, Baltimore, MD 21218
- Program in Molecular Biophysics, Johns Hopkins University, 3400 Charles Street, Baltimore, MD 21218
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35
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Leong SK, Hsiao JC, Shie JJ. A Multiscale Molecular Dynamic Analysis Reveals the Effect of Sialylation on EGFR Clustering in a CRISPR/Cas9-Derived Model. Int J Mol Sci 2022; 23:ijms23158754. [PMID: 35955894 PMCID: PMC9368999 DOI: 10.3390/ijms23158754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 07/28/2022] [Accepted: 08/03/2022] [Indexed: 11/16/2022] Open
Abstract
Bacterial and viral pathogens can modulate the glycosylation of key host proteins to facilitate pathogenesis by using various glycosidases, particularly sialidases. Epidermal growth factor receptor (EGFR) signaling is activated by ligand-induced receptor dimerization and oligomerization. Ligand binding induces conformational changes in EGFR, leading to clusters and aggregation. However, information on the relevance of EGFR clustering in the pattern of glycosylation during bacterial and viral invasion remains unclear. In this study, (1) we established CRISPR/Cas9-mediated GFP knock-in (EGFP-KI) HeLa cells expressing fluorescently tagged EGFR at close to endogenous levels to study EGF-induced EGFR clustering and molecular dynamics; (2) We studied the effect of sialylation on EGF-induced EGFR clustering and localization in live cells using a high content analysis platform and raster image correlation spectroscopy (RICS) coupled with a number and brightness (N&B) analysis; (3) Our data reveal that the removal of cell surface sialic acids by sialidase treatment significantly decreases EGF receptor clustering with reduced fluorescence intensity, number, and area of EGFR-GFP clusters per cell upon EGF stimulation. Sialylation appears to mediate EGF-induced EGFR clustering as demonstrated by the change of EGFR-GFP clusters in the diffusion coefficient and molecular brightness, providing new insights into the role of sialylation in EGF-induced EGFR activation; and (4) We envision that the combination of CRISPR/Cas9-mediated fluorescent tagging of endogenous proteins and fluorescence imaging techniques can be the method of choice for studying the molecular dynamics and interactions of proteins in live cells.
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Affiliation(s)
- Shwee Khuan Leong
- Institute of Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Taiwan International Graduate Program (TIGP), Sustainable Chemical Science & Technology (SCST), Academia Sinica, Taipei 11529, Taiwan
- Department of Applied Chemistry, National Yang Ming Chiao Tung University (NYCU), Hsinchu 30050, Taiwan
| | - Jye-Chian Hsiao
- Institute of Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Jiun-Jie Shie
- Institute of Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Correspondence:
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36
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Ng WS, Sielaff H, Zhao ZW. Phase Separation-Mediated Chromatin Organization and Dynamics: From Imaging-Based Quantitative Characterizations to Functional Implications. Int J Mol Sci 2022; 23:8039. [PMID: 35887384 PMCID: PMC9316379 DOI: 10.3390/ijms23148039] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/18/2022] [Accepted: 07/19/2022] [Indexed: 12/14/2022] Open
Abstract
As an effective and versatile strategy to compartmentalize cellular components without the need for lipid membranes, phase separation has been found to underpin a wide range of intranuclear processes, particularly those involving chromatin. Many of the unique physico-chemical properties of chromatin-based phase condensates are harnessed by the cell to accomplish complex regulatory functions in a spatially and temporally controlled manner. Here, we survey key recent findings on the mechanistic roles of phase separation in regulating the organization and dynamics of chromatin-based molecular processes across length scales, packing states and intranuclear functions, with a particular emphasis on quantitative characterizations of these condensates enabled by advanced imaging-based approaches. By illuminating the complex interplay between chromatin and various chromatin-interacting molecular species mediated by phase separation, this review sheds light on an emerging multi-scale, multi-modal and multi-faceted landscape that hierarchically regulates the genome within the highly crowded and dynamic nuclear space. Moreover, deficiencies in existing studies also highlight the need for mechanism-specific criteria and multi-parametric approaches for the characterization of chromatin-based phase separation using complementary techniques and call for greater efforts to correlate the quantitative features of these condensates with their functional consequences in close-to-native cellular contexts.
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Affiliation(s)
- Woei Shyuan Ng
- Department of Chemistry, Faculty of Science, National University of Singapore, Singapore 119543, Singapore; (W.S.N.); (H.S.)
- Centre for BioImaging Sciences (CBIS), Faculty of Science, National University of Singapore, Singapore 117557, Singapore
| | - Hendrik Sielaff
- Department of Chemistry, Faculty of Science, National University of Singapore, Singapore 119543, Singapore; (W.S.N.); (H.S.)
- Centre for BioImaging Sciences (CBIS), Faculty of Science, National University of Singapore, Singapore 117557, Singapore
| | - Ziqing Winston Zhao
- Department of Chemistry, Faculty of Science, National University of Singapore, Singapore 119543, Singapore; (W.S.N.); (H.S.)
- Centre for BioImaging Sciences (CBIS), Faculty of Science, National University of Singapore, Singapore 117557, Singapore
- Mechanobiology Institute (MBI), National University of Singapore, Singapore 117411, Singapore
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Tollis S. The G1/S repressor WHI5 is expressed at similar levels throughout the cell cycle. BMC Res Notes 2022; 15:248. [PMID: 35841111 PMCID: PMC9284753 DOI: 10.1186/s13104-022-06142-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 06/30/2022] [Indexed: 11/19/2022] Open
Abstract
Objectives While it is clear that cells need to grow before committing to division at the G1/S transition of the cell cycle, how cells sense their growth rate or size at the molecular level is unknown. It has been proposed that, in budding yeast, the dilution of the Whi5 G1/S transcriptional repressor as cells grow in G1 is the main driver of G1/S commitment. This model implies that Whi5 synthesis is substantially reduced in G1 phase. Recent work has reported that the concentration of Whi5 is size- and time-independent in G1 cells, challenging the dilution model. These results in turn imply that Whi5 must be synthesized in G1 phase, but the cell cycle dependence of WHI5 mRNA expression has not been examined in live cells. Results description To address this question, we monitored single WHI5 mRNA molecules in single live cells using confocal microscopy, and quantified WHI5 mRNA copy number in G1, G1/S, and S/G2/M phase cells. We observed that WHI5 mRNA is found in very similar amount irrespective of cell cycle stage. The constant WHI5 mRNA copy number throughout G1 phase rules out alterations in mRNA abundance as a contributing factor for any putative dilution of Whi5. Supplementary Information The online version contains supplementary material available at 10.1186/s13104-022-06142-9.
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Affiliation(s)
- Sylvain Tollis
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.
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38
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Measuring Molecular Diffusion in Dynamic Subcellular Nanostructures by Fast Raster Image Correlation Spectroscopy and 3D Orbital Tracking. Int J Mol Sci 2022; 23:ijms23147623. [PMID: 35886970 PMCID: PMC9323805 DOI: 10.3390/ijms23147623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 06/21/2022] [Accepted: 07/08/2022] [Indexed: 02/04/2023] Open
Abstract
Here we provide demonstration that fast fluorescence fluctuation spectroscopy is a fast and robust approach to extract information on the dynamics of molecules enclosed within subcellular nanostructures (e.g., organelles or vesicles) which are also moving in the complex cellular environment. In more detail, Raster Image Correlation Spectroscopy (RICS) performed at fast timescales (i.e., microseconds) reveals the fast motion of fluorescently labeled molecules within two exemplary dynamic subcellular nanostructures of biomedical interest, the lysosome and the insulin secretory granule (ISG). The measurement of molecular diffusion is then used to extract information on the average properties of subcellular nanostructures, such as macromolecular crowding or molecular aggregation. Concerning the lysosome, fast RICS on a fluorescent tracer allowed us to quantitatively assess the increase in organelle viscosity in the pathological condition of Krabbe disease. In the case of ISGs, fast RICS on two ISG-specific secreting peptides unveiled their differential aggregation propensity depending on intragranular concentration. Finally, a combination of fast RICS and feedback-based 3D orbital tracking was used to subtract the slow movement of subcellular nanostructures from the fast diffusion of molecules contained within them and independently validate the results. Results presented here not only demonstrate the acquired ability to address the dynamic behavior of molecules in moving, nanoscopic reference systems, but prove the relevance of this approach to advance our knowledge on cell function at the subcellular scale.
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Solano A, Lou J, Scipioni L, Gratton E, Hinde E. Radial pair correlation of molecular brightness fluctuations maps protein diffusion as a function of oligomeric state within live-cell nuclear architecture. Biophys J 2022; 121:2152-2167. [PMID: 35490296 PMCID: PMC9247470 DOI: 10.1016/j.bpj.2022.04.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 11/16/2021] [Accepted: 04/26/2022] [Indexed: 11/22/2022] Open
Abstract
Nuclear proteins can modulate their DNA binding activity and the exploration volume available during DNA target search by self-associating into higher-order oligomers. Directly tracking this process in the nucleoplasm of a living cell is, however, a complex task. Thus, here we present a microscopy method based on radial pair correlation of molecular brightness fluctuations (radial pCOMB) that can extract the mobility of a fluorescently tagged nuclear protein as a function of its oligomeric state and spatiotemporally map the anisotropy of this parameter with respect to nuclear architecture. By simply performing a rapid frame scan acquisition, radial pCOMB has the capacity to detect, within each pixel, protein oligomer formation and the size-dependent obstruction nuclear architecture imparts on this complex's transport across sub-micrometer distances. From application of radial pCOMB to an oligomeric transcription factor and DNA repair protein, we demonstrate that homo-oligomer formation differentially regulates chromatin accessibility and interaction with the DNA template.
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Affiliation(s)
- Ashleigh Solano
- School of Physics, University of Melbourne; Department of Biochemistry and Pharmacology, University of Melbourne
| | - Jieqiong Lou
- School of Physics, University of Melbourne; Department of Biochemistry and Pharmacology, University of Melbourne
| | - Lorenzo Scipioni
- Department of Biomedical Engineering, University of California, Irvine
| | - Enrico Gratton
- Department of Biomedical Engineering, University of California, Irvine.
| | - Elizabeth Hinde
- School of Physics, University of Melbourne; Department of Biochemistry and Pharmacology, University of Melbourne.
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40
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Activation of Gαq sequesters specific transcripts into Ago2 particles. Sci Rep 2022; 12:8758. [PMID: 35610292 PMCID: PMC9130320 DOI: 10.1038/s41598-022-12737-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 05/10/2022] [Indexed: 12/13/2022] Open
Abstract
The Gαq/phospholipase Cβ1 (PLCβ1) signaling system mediates calcium responses from hormones and neurotransmitters. While PLCβ1 functions on the plasma membrane, there is an atypical cytosolic population that binds Argonaute 2 (Ago2) and other proteins associated with stress granules preventing their aggregation. Activation of Gαq relocalizes cytosolic PLCβ1 to the membrane, releasing bound proteins, promoting the formation of stress granules. Here, we have characterized Ago2 stress granules associated with Gαq activation in differentiated PC12 cells, which have a robust Gαq/PLCβ1 signaling system. Characterization of Ago2-associated stress granules shows shifts in protein composition when cells are stimulated with a Gαq agonist, or subjected to heat shock or osmotic stress, consistent with the idea that different stresses result in unique stress granules. Purified Ago2 stress granules from control cells do not contain RNA, while those from heat shock contain many different mRNAs and miRs. Surprisingly, Ago2 particles from cells where Gαq was stimulated show only two transcripts, chromogranin B, which is involved in secretory function, and ATP synthase 5f1b, which is required for ATP synthesis. RT-PCR, western blotting and other studies support the idea that Gαq-activation protects these transcripts. Taken together, these studies show a novel pathway where Gαq/PLCβ regulates the translation of specific proteins.
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41
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Qifti A, Balaji S, Scarlata S. Deformation of caveolae impacts global transcription and translation processes through relocalization of cavin-1. J Biol Chem 2022; 298:102005. [PMID: 35513070 PMCID: PMC9168624 DOI: 10.1016/j.jbc.2022.102005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 04/16/2022] [Accepted: 04/19/2022] [Indexed: 11/17/2022] Open
Abstract
Caveolae are invaginated membrane domains that provide mechanical strength to cells in addition to being focal points for the localization of signaling molecules. Caveolae are formed through the aggregation of caveolin-1 or -3 (Cav1/3), membrane proteins that assemble into multifunctional complexes with the help of caveola-associated protein cavin-1. In addition to its role in the formation of caveolae, cavin-1, also called polymerase I and transcript release factor, is further known to promote ribosomal RNA transcription in the nucleus. However, the mechanistic link between these functions is not clear. Here, we found that deforming caveolae by subjecting cells to mild osmotic stress (150–300 mOsm) changes levels of GAPDH, Hsp90, and Ras only when Cav1/cavin-1 levels are reduced, suggesting a link between caveola deformation and global protein expression. We show that this link may be due to relocalization of cavin-1 to the nucleus upon caveola deformation. Cavin-1 relocalization is also seen when Cav1-Gαq contacts change upon stimulation. Furthermore, Cav1 and cavin-1 levels have been shown to have profound effects on cytosolic RNA levels, which in turn impact the ability of cells to form stress granules and RNA-processing bodies (p-bodies) which sequester and degrade mRNAs, respectively. Our studies here using a cavin-1-knockout cell line indicate adaptive changes in cytosolic RNA levels but a reduced ability to form stress granules. Taken together, our findings suggest that caveolae, through release of cavin-1, communicate extracellular cues to the cell interior to impact transcriptional and translational.
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42
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Mitrentsi I, Lou J, Kerjouan A, Verigos J, Reina-San-Martin B, Hinde E, Soutoglou E. Heterochromatic repeat clustering imposes a physical barrier on homologous recombination to prevent chromosomal translocations. Mol Cell 2022; 82:2132-2147.e6. [PMID: 35447083 PMCID: PMC9616805 DOI: 10.1016/j.molcel.2022.03.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 12/15/2021] [Accepted: 03/28/2022] [Indexed: 01/01/2023]
Abstract
Mouse pericentromeric DNA is composed of tandem major satellite repeats, which are heterochromatinized and cluster together to form chromocenters. These clusters are refractory to DNA repair through homologous recombination (HR). The mechanisms by which pericentromeric heterochromatin imposes a barrier on HR and the implications of repeat clustering are unknown. Here, we compare the spatial recruitment of HR factors upon double-stranded DNA breaks (DSBs) induced in human and mouse pericentromeric heterochromatin, which differ in their capacity to form clusters. We show that while DSBs increase the accessibility of human pericentromeric heterochromatin by disrupting HP1α dimerization, mouse pericentromeric heterochromatin repeat clustering imposes a physical barrier that requires many layers of de-compaction to be accessed. Our results support a model in which the 3D organization of heterochromatin dictates the spatial activation of DNA repair pathways and is key to preventing the activation of HR within clustered repeats and the onset of chromosomal translocations. DSBs at human pericentric HC are positionally stable and recruit HR factors Repeat clustering restricts Rad51 at the periphery of heterochromatin Human pericentromeric HC is more accessible to HR factors than mouse HC Inhibition of DSB relocation at clustered repeats leads to translocations
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Affiliation(s)
- Ioanna Mitrentsi
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France; Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Illkirch, France; Centre National de Recherche Scientifique (CNRS), UMR7104, Illkirch, France; Université de Strasbourg, Illkirch, France
| | - Jieqiong Lou
- School of Physics, University of Melbourne, Melbourne, VIC, Australia
| | - Adèle Kerjouan
- School of Physics, University of Melbourne, Melbourne, VIC, Australia
| | - John Verigos
- Genome Damage and Stability Centre, Sussex University, School of Life Sciences, University of Sussex, Brighton, BN1 9RH, UK
| | - Bernardo Reina-San-Martin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France; Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Illkirch, France; Centre National de Recherche Scientifique (CNRS), UMR7104, Illkirch, France; Université de Strasbourg, Illkirch, France
| | - Elizabeth Hinde
- School of Physics, University of Melbourne, Melbourne, VIC, Australia; Department of Biochemistry and Pharmacology, University of Melbourne, Melbourne, VIC, Australia
| | - Evi Soutoglou
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France; Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Illkirch, France; Centre National de Recherche Scientifique (CNRS), UMR7104, Illkirch, France; Université de Strasbourg, Illkirch, France; Genome Damage and Stability Centre, Sussex University, School of Life Sciences, University of Sussex, Brighton, BN1 9RH, UK.
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43
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Hedde PN, Barylko B, Binns DD, Jameson DM, Albanesi JP. Differential Mobility and Self-Association of Arc/Arg3.1 in the Cytoplasm and Nucleus of Living Cells. ACS Chem Neurosci 2022; 13:876-882. [PMID: 35319179 DOI: 10.1021/acschemneuro.1c00744] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Arc, also known as Arg3.1, is an activity-dependent immediate-early gene product that plays essential roles in memory consolidation. A pool of Arc is located in the postsynaptic cytoplasm, where it promotes AMPA receptor endocytosis and cytoskeletal remodeling. However, Arc is also found in the nucleus, with a major portion being associated with promyelocytic leukemia nuclear bodies (PML-NBs). Nuclear Arc has been implicated in epigenetic control of gene transcription associated with learning and memory. In this study, we use a battery of fluorescence nanoimaging approaches to characterize the behavior of Arc ectopically expressed in heterologous cells. Our results indicate that in the cytoplasm, Arc exists predominantly as monomers and dimers associated with slowly diffusing particles. In contrast, nuclear Arc is almost exclusively monomeric and displays a higher diffusivity than cytoplasmic Arc. We further show that Arc moves freely and rapidly between PML-NBs and the nucleoplasm and that its movement within PML-NBs is relatively unobstructed.
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Affiliation(s)
- Per Niklas Hedde
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, 651 Ilalo Street, BSB 222, University of Hawaii, Honolulu, Hawaii 96813, United States
| | - Barbara Barylko
- Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park, Dallas, Texas 75390, United States
| | - Derk D. Binns
- Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park, Dallas, Texas 75390, United States
| | - David M. Jameson
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, 651 Ilalo Street, BSB 222, University of Hawaii, Honolulu, Hawaii 96813, United States
| | - Joseph P. Albanesi
- Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park, Dallas, Texas 75390, United States
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44
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Killeen TD, Rahman S, Badu DN, Biener G, Stoneman MR, Raicu V. Fluorescence Intensity Fluctuation Analysis of Protein Oligomerization in Cell Membranes. Curr Protoc 2022; 2:e384. [PMID: 35312215 DOI: 10.1002/cpz1.384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Fluorescence fluctuation spectroscopy (FFS) encompasses a bevy of techniques that involve analyzing fluorescence intensity fluctuations occurring due to fluorescently labeled molecules diffusing in and out of a microscope's focal region. Statistical analysis of these fluctuations may reveal the oligomerization (i.e., association) state of said molecules. We have recently developed a new FFS-based method, termed Two-Dimensional Fluorescence Intensity Fluctuation (2D FIF) spectrometry, which provides quantitative information on the size and stability of protein oligomers as a function of receptor concentration. This article describes protocols for employing FIF spectrometry to quantify the oligomerization of a membrane protein of interest, with specific instructions regarding cell preparation, image acquisition, and analysis of images given in detail. Application of the FIF Spectrometry Suite, a software package designed for applying FIF analysis on fluorescence images, is emphasized in the protocol. Also discussed in detail is the identification, removal, and/or analysis of inhomogeneous regions of the membrane that appear as bright spots. The 2D FIF approach is particularly suited to assess the effects of agonists and antagonists on the oligomeric size of membrane receptors of interest. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Preparation of live cells expressing protein constructs Basic Protocol 2: Image acquisition and noise correction Basic Protocol 3: Drawing and segmenting regions of interest Basic Protocol 4: Calculating the molecular brightness and concentration of individual image segments Basic Protocol 5: Combining data subsets using a manual procedure (Optional) Alternate Protocol 1: Combining data subsets using the advanced FIF spectrometry suite (Optional; alternative to Basic Protocol 5) Basic Protocol 6: Performing meta-analysis of brightness spectrograms Alternate Protocol 2: Performing meta-analysis of brightness spectrograms (alternative to Basic Protocol 6) Basic Protocol 7: Spot extraction and analysis using a manual procedure or by writing a program (Optional) Alternate Protocol 3: Automated spot extraction and analysis (Optional; alternative to Protocol 7) Support Protocol: Monomeric brightness determination.
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Affiliation(s)
- Tom D Killeen
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Sadia Rahman
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Dammar N Badu
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Gabriel Biener
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Michael R Stoneman
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Valerică Raicu
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin.,Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
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Gelber I. Variance reducing and noise correction in protein quantification by measuring fluctuations in fluorescence due to photobleaching. Phys Biol 2022; 19. [PMID: 35290963 DOI: 10.1088/1478-3975/ac5e0f] [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: 07/26/2021] [Accepted: 03/15/2022] [Indexed: 11/11/2022]
Abstract
Quantifying the absolute protein number using the ratio between the variance and the mean of the protein Fluorescence intensity is a straightforward method for microscopy imaging. Recently, this method has been expanded to fluorescence decaying processes due to photobleaching with binomial distribution. The article examines the method proposed and shows how it can be adapted to the case of variance in the initial number of proteins between the cells. The article shows that the method can be improved by the implementation of the information processing of each frame independently from other frames. By doing so, the variance in determining the protein number can be reduced. In addition, the article examines the management of unwanted noises in the measurement, offers a solution for the shot noise and background noise, examines the expected error caused by the decay constant inaccuracy, and analyzes the expected difficulties in conducting a practical experiment, which includes a non-exponential decay and variance in the photobleaching rate of the cells. The method can be applied to any superposition of n_0 discrete decaying processes. However, the evaluation of expected errors in quantification is essential for early planning of the experimental conditions and evaluation of the error.
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Affiliation(s)
- Itay Gelber
- Department of Physics, Ben-Gurion University of the Negev, beer sheva, Beer-Sheva, 84105, ISRAEL
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46
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The microprotein Nrs1 rewires the G1/S transcriptional machinery during nitrogen limitation in budding yeast. PLoS Biol 2022; 20:e3001548. [PMID: 35239649 PMCID: PMC8893695 DOI: 10.1371/journal.pbio.3001548] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 01/19/2022] [Indexed: 12/01/2022] Open
Abstract
Commitment to cell division at the end of G1 phase, termed Start in the budding yeast Saccharomyces cerevisiae, is strongly influenced by nutrient availability. To identify new dominant activators of Start that might operate under different nutrient conditions, we screened a genome-wide ORF overexpression library for genes that bypass a Start arrest caused by absence of the G1 cyclin Cln3 and the transcriptional activator Bck2. We recovered a hypothetical gene YLR053c, renamed NRS1 for Nitrogen-Responsive Start regulator 1, which encodes a poorly characterized 108 amino acid microprotein. Endogenous Nrs1 was nuclear-localized, restricted to poor nitrogen conditions, induced upon TORC1 inhibition, and cell cycle-regulated with a peak at Start. NRS1 interacted genetically with SWI4 and SWI6, which encode subunits of the main G1/S transcription factor complex SBF. Correspondingly, Nrs1 physically interacted with Swi4 and Swi6 and was localized to G1/S promoter DNA. Nrs1 exhibited inherent transactivation activity, and fusion of Nrs1 to the SBF inhibitor Whi5 was sufficient to suppress other Start defects. Nrs1 appears to be a recently evolved microprotein that rewires the G1/S transcriptional machinery under poor nitrogen conditions. Commitment to cell division at the end of G1 phase in the budding yeast Saccharomyces cerevisiae is strongly influenced by nutrient availability. This study identifies a micro-protein that promotes G1/S transcription activation and cell cycle entry in yeast under nitrogen-limited conditions.
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47
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Yerramilli VS, Ross AH, Scarlata S, Gericke A. IQGAP1 scaffolding links phosphoinositide kinases to cytoskeletal reorganization. Biophys J 2022; 121:793-807. [PMID: 35077666 PMCID: PMC8943696 DOI: 10.1016/j.bpj.2022.01.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 09/24/2021] [Accepted: 01/21/2022] [Indexed: 11/02/2022] Open
Abstract
IQGAP1 is a multidomain scaffold protein that coordinates the direction and impact of multiple signaling pathways by scaffolding its various binding partners. However, the spatial and temporal resolution of IQGAP1 scaffolding remains unclear. Here, we use fluorescence imaging and correlation methods that allow for real-time live-cell changes in IQGAP1 localization and complex formation during signaling. We find that IQGAP1 and PIPKIγ interact on both the plasma membrane and in cytosol. Epidermal growth factor (EGF) stimulation, which can initiate cytoskeletal changes, drives the movement of the cytosolic pool toward the plasma membrane to promote cytoskeletal changes. We also observe that a significant population of cytosolic IQGAP1-PIPKIγ complexes localize to early endosomes, and in some instances form aggregated clusters which become highly mobile upon EGF stimulation. Our imaging studies show that PIPKIγ and PI3K bind simultaneously to IQGAP1, which may accelerate conversion of PI4P to PI(3,4,5)P3 that is required for cytoskeletal changes. Additionally, we find that IQGAP1 is responsible for PIPKIγ association with two proteins associated with cytoskeletal changes, talin and Cdc42, during EGF stimulation. These results directly show that IQGAP1 provides a physical link between phosphoinositides (through PIPKIγ), focal adhesion formation (through talin), and cytoskeletal reorganization (through Cdc42) upon EGF stimulation. Taken together, our results support the importance of IQGAP1 in regulating cell migration by linking phosphoinositide lipid signaling with cytoskeletal reorganization.
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Affiliation(s)
- V. Siddartha Yerramilli
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts
| | - Alonzo H. Ross
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts,Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Suzanne Scarlata
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts
| | - Arne Gericke
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts.
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48
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Balcioglu HE, Harkes R, Danen EHJ, Schmidt T. Substrate rigidity modulates traction forces and stoichiometry of cell–matrix adhesions. J Chem Phys 2022; 156:085101. [DOI: 10.1063/5.0077004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In cell–matrix adhesions, integrin receptors and associated proteins provide a dynamic coupling of the extracellular matrix (ECM) to the cytoskeleton. This allows bidirectional transmission of forces between the ECM and the cytoskeleton, which tunes intracellular signaling cascades that control survival, proliferation, differentiation, and motility. The quantitative relationships between recruitment of distinct cell–matrix adhesion proteins and local cellular traction forces are not known. Here, we applied quantitative super-resolution microscopy to cell–matrix adhesions formed on fibronectin-stamped elastomeric pillars and developed an approach to relate the number of talin, vinculin, paxillin, and focal adhesion kinase (FAK) molecules to the local cellular traction force. We find that FAK recruitment does not show an association with traction-force application, whereas a ∼60 pN force increase is associated with the recruitment of one talin, two vinculin, and two paxillin molecules on a substrate with an effective stiffness of 47 kPa. On a substrate with a fourfold lower effective stiffness, the stoichiometry of talin:vinculin:paxillin changes to 2:12:6 for the same ∼60 pN traction force. The relative change in force-related vinculin recruitment indicates a stiffness-dependent switch in vinculin function in cell–matrix adhesions. Our results reveal a substrate-stiffness-dependent modulation of the relationship between cellular traction-force and the molecular stoichiometry of cell–matrix adhesions.
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Affiliation(s)
- Hayri E. Balcioglu
- Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - Rolf Harkes
- Physics of Life Processes, Kamerlingh Onnes-Huygens Laboratory, Leiden University, Leiden, The Netherlands
| | - Erik H. J. Danen
- Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - Thomas Schmidt
- Physics of Life Processes, Kamerlingh Onnes-Huygens Laboratory, Leiden University, Leiden, The Netherlands
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Welke RW, Sperber HS, Bergmann R, Koikkarah A, Menke L, Sieben C, Krüger DH, Chiantia S, Herrmann A, Schwarzer R. Characterization of Hantavirus N Protein Intracellular Dynamics and Localization. Viruses 2022; 14:v14030457. [PMID: 35336863 PMCID: PMC8954124 DOI: 10.3390/v14030457] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Revised: 02/02/2022] [Accepted: 02/18/2022] [Indexed: 02/07/2023] Open
Abstract
Hantaviruses are enveloped viruses that possess a tri-segmented, negative-sense RNA genome. The viral S-segment encodes the multifunctional nucleocapsid protein (N), which is involved in genome packaging, intracellular protein transport, immunoregulation, and several other crucial processes during hantavirus infection. In this study, we generated fluorescently tagged N protein constructs derived from Puumalavirus (PUUV), the dominant hantavirus species in Central, Northern, and Eastern Europe. We comprehensively characterized this protein in the rodent cell line CHO-K1, monitoring the dynamics of N protein complex formation and investigating co-localization with host proteins as well as the viral glycoproteins Gc and Gn. We observed formation of large, fibrillar PUUV N protein aggregates, rapidly coalescing from early punctate and spike-like assemblies. Moreover, we found significant spatial correlation of N with vimentin, actin, and P-bodies but not with microtubules. N constructs also co-localized with Gn and Gc albeit not as strongly as the glycoproteins associated with each other. Finally, we assessed oligomerization of N constructs, observing efficient and concentration-dependent multimerization, with complexes comprising more than 10 individual proteins.
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Affiliation(s)
- Robert-William Welke
- Department of Molecular Biophysics, Humboldt University, 10115 Berlin, Germany; (R.-W.W.); (R.B.); (A.H.)
| | - Hannah Sabeth Sperber
- Institute for Translational HIV Research, University Hospital Essen, 45147 Essen, Germany;
| | - Ronny Bergmann
- Department of Molecular Biophysics, Humboldt University, 10115 Berlin, Germany; (R.-W.W.); (R.B.); (A.H.)
| | - Amit Koikkarah
- Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany; (A.K.); (S.C.)
| | - Laura Menke
- Nanoscale Infection Biology Group, Department of Cell Biology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany; (L.M.); (C.S.)
| | - Christian Sieben
- Nanoscale Infection Biology Group, Department of Cell Biology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany; (L.M.); (C.S.)
- Institute for Genetics, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Detlev H. Krüger
- Institut für Virologie, Charité–Universitätsmedizin Berlin, Gliedkörperschaft der Freien Universität Berlin und der Humboldt-Universität zu Berlin, 10117 Berlin, Germany;
| | - Salvatore Chiantia
- Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany; (A.K.); (S.C.)
| | - Andreas Herrmann
- Department of Molecular Biophysics, Humboldt University, 10115 Berlin, Germany; (R.-W.W.); (R.B.); (A.H.)
- Biophysikalische Chemie, Freie Universität, 14195 Berlin, Germany
| | - Roland Schwarzer
- Institute for Translational HIV Research, University Hospital Essen, 45147 Essen, Germany;
- Correspondence:
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50
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Van den Broeck L, Gobble M, Sozzani R. Quantifying Intercellular Movement and Protein Stoichiometry for Computational Modeling. Methods Mol Biol 2022; 2457:367-382. [PMID: 35349154 DOI: 10.1007/978-1-0716-2132-5_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Analyzing protein movement dynamics and their regulation has shown to be important in the study of cell fate decisions. Such analyses can be performed with scanning fluorescence correlation spectroscopy (scanning FCS), a versatile imaging methodology that has been applied in the animal kingdom and recently adapted to the plant kingdom. Specifically, scanning FCS allows for qualitatively capturing protein movement across barriers, such as the active transport through plasmodesmata, the analysis of protein movement rates, and the quantification of the stoichiometry of protein complexes, composed of one or more different proteins. Importantly, the quantifiable data generated with scanning FCS can be used to inform computational models, enhancing model simulations of in vivo events, such as cell fate decisions, during plant development.
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Affiliation(s)
- Lisa Van den Broeck
- Plant and Microbial Biology Department, North Carolina State University, Raleigh, NC, USA
| | - Mariah Gobble
- Plant and Microbial Biology Department, North Carolina State University, Raleigh, NC, USA
| | - Rosangela Sozzani
- Plant and Microbial Biology Department, North Carolina State University, Raleigh, NC, USA.
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