1
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Isola M, Maxia C, Murtas D, Ekström J, Isola R, Loy F. Prostate-specific antigen: An unfamiliar protein in the human salivary glands. J Anat 2024; 244:873-881. [PMID: 38111134 PMCID: PMC11021670 DOI: 10.1111/joa.13996] [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] [Received: 10/09/2023] [Revised: 11/09/2023] [Accepted: 12/04/2023] [Indexed: 12/20/2023] Open
Abstract
OBJECTIVES The presence of prostate-specific antigen (PSA) in saliva and salivary glands has been reported. Nevertheless, its release pathway in these glands remains to be elucidated. Here, we showed PSA subcellular distribution focusing on its plausible route in human salivary parenchyma. MATERIALS AND METHODS Sections of parotid and submandibular glands were subjected to the immunohistochemical demonstration of PSA by the streptavidin-biotin method revealed by alkaline phosphatase. Moreover, ultrathin sections were collected on nickel grids and processed for immunocytochemical analysis, to visualize the intracellular distribution pattern of PSA through the observation by transmission electron microscopy. RESULTS By immunohistochemistry, in both parotid and submandibular glands PSA expression was detected in serous secretory acini and striated ducts. By immunocytochemistry, immunoreactivity was retrieved in the cytoplasmic compartment of acinar and ductal cells, often associated with small cytoplasmic vesicles. PSA labeling appeared also on rough endoplasmic reticulum and in the acini's lumen. A negligible PSA labeling appeared in most of the secretory granules of both glands. CONCLUSIONS Our findings clearly support that human parotid and submandibular glands are involved in PSA secretion. Moreover, based on the immunoreactivity pattern, its release in oral cavity would probably occur by minor regulated secretory or constitutive-like secretory pathways.
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Affiliation(s)
- Michela Isola
- Department of Biomedical SciencesUniversity of CagliariCagliariItaly
| | - Cristina Maxia
- Department of Biomedical SciencesUniversity of CagliariCagliariItaly
| | - Daniela Murtas
- Department of Biomedical SciencesUniversity of CagliariCagliariItaly
| | - Jörgen Ekström
- Division of Pharmacology, Institute of Neuroscience and PhysiologySahlgrenska Academy at the University of GothenburgGöteborgSweden
| | - Raffaella Isola
- Department of Biomedical SciencesUniversity of CagliariCagliariItaly
| | - Francesco Loy
- Department of Biomedical SciencesUniversity of CagliariCagliariItaly
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2
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Rueckel M, Janson S, Solbak A, Fickler A. Spatial activity mapping of ß-mannanase on soybean seeds. Sci Rep 2024; 14:1037. [PMID: 38200142 PMCID: PMC10781726 DOI: 10.1038/s41598-024-51494-w] [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] [Received: 09/12/2023] [Accepted: 01/05/2024] [Indexed: 01/12/2024] Open
Abstract
For farm animals the supplementation of exogenous enzymes, like ß-mannanase, to soybean-based diets is beneficial to improve feed digestibility. In order to unravel the effect of ß-mannanase on soybean meal's cell structure, a novel imaging concept was developed which allows visualizing the spatial activity pattern of ß-mannanase with high sensitivity by fluorescence microscopy before any visible degradation of the cellular structure occurs. It is based on fluorescence labeling of newly formed reducing ends of ß-mannanase-hydrolyzed polysaccharides after the native reducing ends of all polysaccharides present were chemically reduced. It was revealed that ß-mannanase is not only active at the cell wall but also at previously unknown sites, like the middle lamella and, most prominently, at an intracellular matrix enclosing the protein storage vacuoles. Based on these findings it can be hypothesized that the evaluated ß-mannanase can degrade the enclosing matrix of encapsulated proteins and the cell wall structure and thereby improves efficiency of feed utilization.
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Affiliation(s)
- Markus Rueckel
- BASF SE, Carl-Bosch-Straße 38, 67056, Ludwigshafen, Germany.
| | - Sven Janson
- BASF SE, Carl-Bosch-Straße 38, 67056, Ludwigshafen, Germany
| | - Arne Solbak
- BASF Enzymes LLC, 3550 John Hopkins Court, San Diego, CA, 92121, USA
| | - Anna Fickler
- BASF SE, Carl-Bosch-Straße 38, 67056, Ludwigshafen, Germany
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3
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Libard S, Hodik M, Cesarini KG, Dragomir A, Alafuzoff I. The Compartmentalization of Amyloid-β in Idiopathic Normal Pressure Hydrocephalus Brain Biopsies. J Alzheimers Dis 2024; 99:729-737. [PMID: 38669551 PMCID: PMC11191527 DOI: 10.3233/jad-240167] [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] [Accepted: 03/21/2024] [Indexed: 04/28/2024]
Abstract
Background Amyloid-β (Aβ) is one of the hallmark lesions of Alzheimer's disease (AD). During the disease process, Aβ undergoes biochemical changes, producing toxic Aβ variants, proposed to be detected within the neurons. Idiopathic normal pressure hydrocephalus (iNPH) causes cognitive impairment, gait, and urinary symptoms in elderly, that can be reversed by a ventriculo-peritoneal shunt. Majority of iNPH subjects display different Aβ variants in their brain biopsies, obtained during shunting. Objective To study the cellular compartmentalization of different Aβ variants in brain biopsies from iNPH subjects. Methods We studied the cellular localization of different proteoforms of Aβ using antibodies towards different amino acid sequences or post-translational modifications of Aβ, including clones 4G8, 6F/3D, unmodified- (7H3D6), pyroglutamylated- (N3pE), phosphorylated-(1E4E11) Aβ and Aβ protein precursor (AβPP), in brain biopsies from 3 iNPH subjects, using immunohistochemistry and light microscopy (LM), light microscopy on semi-thin sections (LMst), and electron microscopy (EM). Results In LM all Aβ variants were detected. In LMst and EM, the Aβ 4G8, 6F/3D, and the pyroglutamylated Aβ were detected. The AβPP was visualized by all methods. The Aβ labelling was located extracellularly with no specific signal within the intracellular compartment, whereas the AβPP was seen both intra- and extracellularly. Conclusions The Aβ markers displayed extracellular localization when visualized by three assessment techniques, reflecting the pathological extracellular accumulation of Aβ in the human brain. No intracellular Aβ pathology was seen. AβPP was visualized in intra- and extracellularly, which corresponds to the localization of the protein in the membranes of cells and organelles.
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Affiliation(s)
- Sylwia Libard
- Department of Pathology, Uppsala University Hospital, Uppsala, Sweden
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Monika Hodik
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
- BioVis Platform, Uppsala University, Uppsala, Sweden
| | | | - Anca Dragomir
- Department of Pathology, Uppsala University Hospital, Uppsala, Sweden
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Irina Alafuzoff
- Department of Pathology, Uppsala University Hospital, Uppsala, Sweden
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4
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Beatty KE, López CS. Characteristics of genetic tags for correlative light and electron microscopy. Curr Opin Chem Biol 2023; 76:102369. [PMID: 37453163 DOI: 10.1016/j.cbpa.2023.102369] [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: 05/01/2023] [Revised: 06/08/2023] [Accepted: 06/19/2023] [Indexed: 07/18/2023]
Abstract
Fluorescence microscopy is indispensable in live cell studies of fluorescently-labeled proteins, but has limited resolution and context. Electron microscopy offers high-resolution imaging of cellular ultrastructure, including membranes, organelles, and other nanoscale features. However, identifying proteins by EM remains a substantial challenge. There is potential to combine the strengths of both FM and EM through correlative light and EM (CLEM), and bridging the two modalities enables new discoveries and biological insights. CLEM enables cellular proteins to be observed dynamically, across size scales, and in relationship to sub-cellular structures. A central limitation to using CLEM is the scarcity of methods for labeling proteins with CLEM reporters. This review will describe the characteristics of genetic tags for CLEM that are available today, including fixation-resistant fluorescent proteins, 3,3'-diaminobenzidine (DAB)-based tags, metal-chelating tags, DNA origami tags, and VIP tags.
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Affiliation(s)
- Kimberly E Beatty
- Department of Chemical Physiology and Biochemistry Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
| | - Claudia S López
- Department of Biomedical Engineering Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
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5
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Marin Z, Fuentes LA, Bewersdorf J, Baddeley D. Extracting nanoscale membrane morphology from single-molecule localizations. Biophys J 2023; 122:3022-3030. [PMID: 37355772 PMCID: PMC10432223 DOI: 10.1016/j.bpj.2023.06.010] [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: 03/08/2023] [Revised: 05/17/2023] [Accepted: 06/15/2023] [Indexed: 06/26/2023] Open
Abstract
Membrane surface reconstruction at the nanometer scale is required for understanding mechanisms of subcellular shape change. This historically has been the domain of electron microscopy, but extraction of surfaces from specific labels is a difficult task in this imaging modality. Existing methods for extracting surfaces from fluorescence microscopy have poor resolution or require high-quality super-resolution data that are manually cleaned and curated. Here, we present NanoWrap, a new method for extracting surfaces from generalized single-molecule localization microscopy data. This makes it possible to study the shape of specifically labeled membranous structures inside cells. We validate NanoWrap using simulations and demonstrate its reconstruction capabilities on single-molecule localization microscopy data of the endoplasmic reticulum and mitochondria. NanoWrap is implemented in the open-source Python Microscopy Environment.
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Affiliation(s)
- Zach Marin
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand; Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut; Department of Biomedical Engineering, Yale University, New Haven, Connecticut
| | - Lukas A Fuentes
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut
| | - Joerg Bewersdorf
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut; Department of Biomedical Engineering, Yale University, New Haven, Connecticut; Department of Physics, Yale University, New Haven, Connecticut
| | - David Baddeley
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand; Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut.
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6
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Burgoyne T, Futter CE. Gold Particle Analyser: Detection and quantitative assessment of electron microscopy gold probes. PLoS One 2023; 18:e0288811. [PMID: 37506104 PMCID: PMC10381077 DOI: 10.1371/journal.pone.0288811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 07/05/2023] [Indexed: 07/30/2023] Open
Abstract
Gold particle probes are an essential electron microscopy tool to examine protein localisation, as well as protein trafficking. They can be introduced into living cells when conjugated to a protein that is endocytosed or to an antibody against a cell surface protein. Alternatively, gold particles can be introduced into fixed cells or tissue when conjugated to antibodies, immunoglobulin binding molecules or chemical probes applied to permeabilised samples or electron microscopy sections. Colloidal gold particles that have not been enlarged through chemical (gold or silver) enhancement are typically spherical and can be prepared in a range of specific sizes, allowing multiple proteins to be localised within a single sample. The typically homogeneous shape and size of the colloidal gold makes them ideal for computer assisted detection and analysis. Here we demonstrate a program developed to automatically identify two sizes of gold particle and perform a range of analyses that includes (i) distribution and cluster analysis; (ii) selection and analysis of gold particles allocated close to or either side of a membrane; (iii) measurement of organelle size; (iv) estimation of the number of gold particles within an aggregate and (v) the detection of chemically enhanced irregular sized and shaped gold particles. We show this easy-to-use program can greatly assist electron microscopists, to reliably and efficiently analyse gold particles within their images.
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Affiliation(s)
- Thomas Burgoyne
- UCL Institute of Ophthalmology, London, United Kingdom
- Royal Brompton Hospital, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
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7
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Marin Z, Fuentes LA, Bewersdorf J, Baddeley D. Extracting nanoscale membrane morphology from single-molecule localizations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.26.525798. [PMID: 36945449 PMCID: PMC10028748 DOI: 10.1101/2023.01.26.525798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Membrane surface reconstruction at the nanometer scale is required for understanding mechanisms of subcellular shape change. This historically has been the domain of electron microscopy, but extraction of surfaces from specific labels is a difficult task in this imaging modality. Existing methods for extracting surfaces from fluorescence microscopy have poor resolution or require high-quality super-resolution data that is manually cleaned and curated. Here we present a new method for extracting surfaces from generalized single-molecule localization microscopy (SMLM) data. This makes it possible to study the shape of specifically-labelled membraneous structures inside of cells. We validate our method using simulations and demonstrate its reconstruction capabilities on SMLM data of the endoplasmic reticulum and mitochondria. Our method is implemented in the open-source Python Microscopy Environment. SIGNIFICANCE We introduce a novel tool for reconstruction of subcellular membrane surfaces from single-molecule localization microscopy data and use it to visualize and quantify local shape and membrane-membrane interactions. We benchmark its performance on simulated data and demonstrate its fidelity to experimental data.
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8
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Yakovian O, Sajman J, Alon M, Arafeh R, Samuels Y, Sherman E. NRas activity is regulated by dynamic interactions with nanoscale signaling clusters at the plasma membrane. iScience 2022; 25:105282. [PMID: 36304112 PMCID: PMC9593252 DOI: 10.1016/j.isci.2022.105282] [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: 02/17/2022] [Revised: 06/07/2022] [Accepted: 10/04/2022] [Indexed: 11/28/2022] Open
Abstract
NRas is a key mediator of the mitogenic pathway in normal cells and in cancer cells. Its dynamics and nanoscale organization at the plasma membrane (PM) facilitate its signaling. Here, we used two-color photoactivated localization microscopy to resolve the organization of individual NRas and associated signaling proteins in live melanoma cells, with resolution down to ∼20 nm. Upon EGF activation, a fraction of NRas and BRAF (dis)assembled synchronously at the PM in co-clusters. NRas and BRAF clusters associated with GPI-enriched domains, serving as possible nucleation sites for these clusters. NRas and BRAF association in mutual clusters was reduced by the NRas farnesylation inhibitor lonafarnib, yet enhanced by the BRAF inhibitor vemurafenib. Surprisingly, dispersed NRas molecules associated with the periphery of self-clusters of either Grb2 or NF1. Thus, NRas-mediated signaling, which is critical in health and disease, is regulated by dynamic interactions with functional clusters of BRAF or other related proteins at the PM.
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Affiliation(s)
- Oren Yakovian
- Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel
| | - Julia Sajman
- Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel
| | - Michal Alon
- Department of Molecular Cell Biology, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Rand Arafeh
- Department of Molecular Cell Biology, Weizmann Institute of Science, 7610001 Rehovot, Israel,Department of Molecular Oncology, Dana Farber Cancer Institute, Boston, MA, USA
| | - Yardena Samuels
- Department of Molecular Cell Biology, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Eilon Sherman
- Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel,Corresponding author
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9
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Vanslembrouck B, Chen JH, Larabell C, van Hengel J. Microscopic Visualization of Cell-Cell Adhesion Complexes at Micro and Nanoscale. Front Cell Dev Biol 2022; 10:819534. [PMID: 35517500 PMCID: PMC9065677 DOI: 10.3389/fcell.2022.819534] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Accepted: 03/21/2022] [Indexed: 12/25/2022] Open
Abstract
Considerable progress has been made in our knowledge of the morphological and functional varieties of anchoring junctions. Cell-cell adhesion contacts consist of discrete junctional structures responsible for the mechanical coupling of cytoskeletons and allow the transmission of mechanical signals across the cell collective. The three main adhesion complexes are adherens junctions, tight junctions, and desmosomes. Microscopy has played a fundamental role in understanding these adhesion complexes on different levels in both physiological and pathological conditions. In this review, we discuss the main light and electron microscopy techniques used to unravel the structure and composition of the three cell-cell contacts in epithelial and endothelial cells. It functions as a guide to pick the appropriate imaging technique(s) for the adhesion complexes of interest. We also point out the latest techniques that have emerged. At the end, we discuss the problems investigators encounter during their cell-cell adhesion research using microscopic techniques.
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Affiliation(s)
- Bieke Vanslembrouck
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Department of Anatomy, University of San Francisco, San Francisco, CA, United States
- *Correspondence: Bieke Vanslembrouck, ; Jolanda van Hengel,
| | - Jian-hua Chen
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Department of Anatomy, University of San Francisco, San Francisco, CA, United States
| | - Carolyn Larabell
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Department of Anatomy, University of San Francisco, San Francisco, CA, United States
| | - Jolanda van Hengel
- Medical Cell Biology Research Group, Department of Human Structure and Repair, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
- *Correspondence: Bieke Vanslembrouck, ; Jolanda van Hengel,
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10
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Approach to map nanotopography of cell surface receptors. Commun Biol 2022; 5:218. [PMID: 35264712 PMCID: PMC8907216 DOI: 10.1038/s42003-022-03152-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 02/09/2022] [Indexed: 12/18/2022] Open
Abstract
Cells communicate with their environment via surface receptors, but nanoscopic receptor organization with respect to complex cell surface morphology remains unclear. This is mainly due to a lack of accessible, robust and high-resolution methods. Here, we present an approach for mapping the topography of receptors at the cell surface with nanometer precision. The method involves coating glass coverslips with glycine, which preserves the fine membrane morphology while allowing immobilized cells to be positioned close to the optical surface. We developed an advanced and simplified algorithm for the analysis of single-molecule localization data acquired in a biplane detection scheme. These advancements enable direct and quantitative mapping of protein distribution on ruffled plasma membranes with near isotropic 3D nanometer resolution. As demonstrated successfully for CD4 and CD45 receptors, the described workflow is a straightforward quantitative technique to study molecules and their interactions at the complex surface nanomorphology of differentiated metazoan cells. A super-resolution localisation-based method is shown to map receptor topography in immune cells, which allows quantitative study of molecules and their interactions at the complex surface nanomorphology of cells.
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11
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Watson ER, Taherian Fard A, Mar JC. Computational Methods for Single-Cell Imaging and Omics Data Integration. Front Mol Biosci 2022; 8:768106. [PMID: 35111809 PMCID: PMC8801747 DOI: 10.3389/fmolb.2021.768106] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 11/29/2021] [Indexed: 12/12/2022] Open
Abstract
Integrating single cell omics and single cell imaging allows for a more effective characterisation of the underlying mechanisms that drive a phenotype at the tissue level, creating a comprehensive profile at the cellular level. Although the use of imaging data is well established in biomedical research, its primary application has been to observe phenotypes at the tissue or organ level, often using medical imaging techniques such as MRI, CT, and PET. These imaging technologies complement omics-based data in biomedical research because they are helpful for identifying associations between genotype and phenotype, along with functional changes occurring at the tissue level. Single cell imaging can act as an intermediary between these levels. Meanwhile new technologies continue to arrive that can be used to interrogate the genome of single cells and its related omics datasets. As these two areas, single cell imaging and single cell omics, each advance independently with the development of novel techniques, the opportunity to integrate these data types becomes more and more attractive. This review outlines some of the technologies and methods currently available for generating, processing, and analysing single-cell omics- and imaging data, and how they could be integrated to further our understanding of complex biological phenomena like ageing. We include an emphasis on machine learning algorithms because of their ability to identify complex patterns in large multidimensional data.
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Affiliation(s)
| | - Atefeh Taherian Fard
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, Australia
| | - Jessica Cara Mar
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, Australia
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12
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van der Beek J, de Heus C, Liv N, Klumperman J. Quantitative correlative microscopy reveals the ultrastructural distribution of endogenous endosomal proteins. J Cell Biol 2022; 221:212877. [PMID: 34817533 PMCID: PMC8624803 DOI: 10.1083/jcb.202106044] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 10/22/2021] [Accepted: 11/01/2021] [Indexed: 02/07/2023] Open
Abstract
The key endosomal regulators Rab5, EEA1, and APPL1 are frequently applied in fluorescence microscopy to mark early endosomes, whereas Rab7 is used as a marker for late endosomes and lysosomes. However, endogenous levels of these proteins localize poorly in immuno-EM, and systematic studies on their native ultrastructural distributions are lacking. To address this gap, we here present a quantitative, on-section correlative light and electron microscopy (CLEM) approach. Using the sensitivity of fluorescence microscopy, we label hundreds of organelles that are subsequently visualized by EM and classified by ultrastructure. We show that Rab5 predominantly marks small, endocytic vesicles and early endosomes. EEA1 colocalizes with Rab5 on early endosomes, but unexpectedly also labels Rab5-negative late endosomes, which are positive for PI(3)P but lack Rab7. APPL1 is restricted to small Rab5-positive, tubulo-vesicular profiles. Rab7 primarily labels late endosomes and lysosomes. These data increase our understanding of the structural-functional organization of the endosomal system and introduce quantitative CLEM as a sensitive alternative for immuno-EM.
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Affiliation(s)
- Jan van der Beek
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Institute of Biomembranes, Utrecht University, Utrecht, the Netherlands
| | - Cecilia de Heus
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Institute of Biomembranes, Utrecht University, Utrecht, the Netherlands
| | - Nalan Liv
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Institute of Biomembranes, Utrecht University, Utrecht, the Netherlands
| | - Judith Klumperman
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Institute of Biomembranes, Utrecht University, Utrecht, the Netherlands
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13
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Just Seeing Is Not Enough for Believing: Immunolabelling as Indisputable Proof of SARS-CoV-2 Virions in Infected Tissue. Viruses 2021; 13:v13091816. [PMID: 34578398 PMCID: PMC8473209 DOI: 10.3390/v13091816] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 09/06/2021] [Accepted: 09/07/2021] [Indexed: 11/16/2022] Open
Abstract
Background: There is increasing evidence that identification of SARS-CoV-2 virions by transmission electron microscopy could be misleading due to the similar morphology of virions and ubiquitous cell structures. This study thus aimed to establish methods for indisputable proof of the presence of SARS-CoV-2 virions in the observed tissue. Methods: We developed a variant of the correlative microscopy approach for SARS-CoV-2 protein identification using immunohistochemical labelling of SARS-CoV-2 proteins on light and electron microscopy levels. We also performed immunogold labelling of SARS-CoV-2 virions. Results: Immunohistochemistry (IHC) of SARS-CoV-2 nucleocapsid proteins and subsequent correlative microscopy undoubtedly proved the presence of SARS-CoV-2 virions in the analysed human nasopharyngeal tissue. The presence of SARS-CoV-2 virions was also confirmed by immunogold labelling for the first time. Conclusions: Immunoelectron microscopy is the most reliable method for distinguishing intracellular viral particles from normal cell structures of similar morphology and size as virions. Furthermore, we developed a variant of correlative microscopy that allows pathologists to check the results of IHC performed first on routinely used paraffin-embedded samples, followed by semithin, and finally by ultrathin sections. Both methodological approaches indisputably proved the presence of SARS-CoV-2 virions in cells.
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14
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Frutiger A, Tanno A, Hwu S, Tiefenauer RF, Vörös J, Nakatsuka N. Nonspecific Binding-Fundamental Concepts and Consequences for Biosensing Applications. Chem Rev 2021; 121:8095-8160. [PMID: 34105942 DOI: 10.1021/acs.chemrev.1c00044] [Citation(s) in RCA: 92] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nature achieves differentiation of specific and nonspecific binding in molecular interactions through precise control of biomolecules in space and time. Artificial systems such as biosensors that rely on distinguishing specific molecular binding events in a sea of nonspecific interactions have struggled to overcome this issue. Despite the numerous technological advancements in biosensor technologies, nonspecific binding has remained a critical bottleneck due to the lack of a fundamental understanding of the phenomenon. To date, the identity, cause, and influence of nonspecific binding remain topics of debate within the scientific community. In this review, we discuss the evolution of the concept of nonspecific binding over the past five decades based upon the thermodynamic, intermolecular, and structural perspectives to provide classification frameworks for biomolecular interactions. Further, we introduce various theoretical models that predict the expected behavior of biosensors in physiologically relevant environments to calculate the theoretical detection limit and to optimize sensor performance. We conclude by discussing existing practical approaches to tackle the nonspecific binding challenge in vitro for biosensing platforms and how we can both address and harness nonspecific interactions for in vivo systems.
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Affiliation(s)
- Andreas Frutiger
- Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zürich, Zürich CH-8092, Switzerland
| | - Alexander Tanno
- Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zürich, Zürich CH-8092, Switzerland
| | - Stephanie Hwu
- Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zürich, Zürich CH-8092, Switzerland
| | - Raphael F Tiefenauer
- Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zürich, Zürich CH-8092, Switzerland
| | - János Vörös
- Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zürich, Zürich CH-8092, Switzerland
| | - Nako Nakatsuka
- Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zürich, Zürich CH-8092, Switzerland
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15
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Sinclair AN, Huynh CT, Sladewski TE, Zuromski JL, Ruiz AE, de Graffenried CL. The Trypanosoma brucei subpellicular microtubule array is organized into functionally discrete subdomains defined by microtubule associated proteins. PLoS Pathog 2021; 17:e1009588. [PMID: 34010336 PMCID: PMC8168904 DOI: 10.1371/journal.ppat.1009588] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 06/01/2021] [Accepted: 04/25/2021] [Indexed: 11/19/2022] Open
Abstract
Microtubules are inherently dynamic cytoskeletal polymers whose length and organization can be altered to perform essential functions in eukaryotic cells, such as providing tracks for intracellular trafficking and forming the mitotic spindle. Microtubules can be bundled to create more stable structures that collectively propagate force, such as in the flagellar axoneme, which provides motility. The subpellicular microtubule array of the protist parasite Trypanosoma brucei, the causative agent of African sleeping sickness, is a remarkable example of a highly specialized microtubule bundle. It is comprised of a single layer of microtubules that are crosslinked to each other and to the overlying plasma membrane. The array microtubules appear to be highly stable and remain intact throughout the cell cycle, but very little is known about the pathways that tune microtubule properties in trypanosomatids. Here, we show that the subpellicular microtubule array is organized into subdomains that consist of differentially localized array-associated proteins at the array posterior, middle, and anterior. The array-associated protein PAVE1 stabilizes array microtubules at the cell posterior and is essential for maintaining its tapered shape. PAVE1 and the newly identified protein PAVE2 form a complex that binds directly to the microtubule lattice, demonstrating that they are a true kinetoplastid-specific MAP. TbAIR9, which localizes to the entirety of the subpellicular array, is necessary for maintaining the localization of array-associated proteins within their respective subdomains of the array. The arrangement of proteins within the array likely tunes the local properties of array microtubules and creates the asymmetric shape of the cell, which is essential for parasite viability.
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Affiliation(s)
- Amy N. Sinclair
- Department of Molecular Microbiology and Immunology, Brown University, Providence, Rhode Island, United States of America
| | - Christine T. Huynh
- Department of Molecular Microbiology and Immunology, Brown University, Providence, Rhode Island, United States of America
| | - Thomas E. Sladewski
- Department of Molecular Microbiology and Immunology, Brown University, Providence, Rhode Island, United States of America
| | - Jenna L. Zuromski
- Department of Pathology and Laboratory Medicine, Center for International Health Research, Brown University, Providence, Rhode Island, United States of America
| | - Amanda E. Ruiz
- Department of Pathology and Laboratory Medicine, Center for International Health Research, Brown University, Providence, Rhode Island, United States of America
| | - Christopher L. de Graffenried
- Department of Molecular Microbiology and Immunology, Brown University, Providence, Rhode Island, United States of America
- * E-mail:
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16
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Lange F, Agüi-Gonzalez P, Riedel D, Phan NTN, Jakobs S, Rizzoli SO. Correlative fluorescence microscopy, transmission electron microscopy and secondary ion mass spectrometry (CLEM-SIMS) for cellular imaging. PLoS One 2021; 16:e0240768. [PMID: 33970908 PMCID: PMC8109779 DOI: 10.1371/journal.pone.0240768] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 04/13/2021] [Indexed: 11/24/2022] Open
Abstract
Electron microscopy (EM) has been employed for decades to analyze cell structure. To also analyze the positions and functions of specific proteins, one typically relies on immuno-EM or on a correlation with fluorescence microscopy, in the form of correlated light and electron microscopy (CLEM). Nevertheless, neither of these procedures is able to also address the isotopic composition of cells. To solve this, a correlation with secondary ion mass spectrometry (SIMS) would be necessary. SIMS has been correlated in the past to EM or to fluorescence microscopy in biological samples, but not to CLEM. We achieved this here, using a protocol based on transmission EM, conventional epifluorescence microscopy and nanoSIMS. The protocol is easily applied, and enables the use of all three technologies at high performance parameters. We suggest that CLEM-SIMS will provide substantial information that is currently beyond the scope of conventional correlative approaches.
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Affiliation(s)
- Felix Lange
- Research Group Mitochondrial Structure and Dynamics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Clinic for Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Paola Agüi-Gonzalez
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Dietmar Riedel
- Laboratory of Electron Microscopy, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Nhu T. N. Phan
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Stefan Jakobs
- Research Group Mitochondrial Structure and Dynamics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Clinic for Neurology, University Medical Center Göttingen, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- * E-mail: (SJ); (SOR)
| | - Silvio O. Rizzoli
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- * E-mail: (SJ); (SOR)
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17
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Harper CB, Smillie KJ. Current molecular approaches to investigate pre-synaptic dysfunction. J Neurochem 2021; 157:107-129. [PMID: 33544872 DOI: 10.1111/jnc.15316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/19/2022]
Abstract
Over the course of the last few decades it has become clear that many neurodevelopmental and neurodegenerative disorders have a synaptic defect, which contributes to pathogenicity. A rise in new techniques, and in particular '-omics'-based methods providing large datasets, has led to an increase in potential proteins and pathways implicated in synaptic function and related disorders. Additionally, advancements in imaging techniques have led to the recent discovery of alternative modes of synaptic vesicle recycling. This has resulted in a lack of clarity over the precise role of different pathways in maintaining synaptic function and whether these new pathways are dysfunctional in neurodevelopmental and neurodegenerative disorders. A greater understanding of the molecular detail of pre-synaptic function in health and disease is key to targeting new proteins and pathways for novel treatments and the variety of new techniques currently available provides an ideal opportunity to investigate these functions. This review focuses on techniques to interrogate pre-synaptic function, concentrating mainly on synaptic vesicle recycling. It further examines techniques to determine the underlying molecular mechanism of pre-synaptic dysfunction and discusses methods to identify molecular targets, along with protein-protein interactions and cellular localization. In combination, these techniques will provide an expanding and more complete picture of pre-synaptic function. With the application of recent technological advances, we are able to resolve events with higher spatial and temporal resolution, leading research towards a greater understanding of dysfunction at the presynapse and the role it plays in pathogenicity.
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Affiliation(s)
- Callista B Harper
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
| | - Karen J Smillie
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
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18
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Yakovian O, Sajman J, Arafeh R, Neve-Oz Y, Alon M, Samuels Y, Sherman E. MEK Inhibition Reverses Aberrant Signaling in Melanoma Cells through Reorganization of NRas and BRAF in Self Nanoclusters. Cancer Res 2021; 81:1279-1292. [PMID: 33355187 DOI: 10.1158/0008-5472.can-20-1205] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 07/29/2020] [Accepted: 12/14/2020] [Indexed: 11/16/2022]
Abstract
Hotspot mutations of the oncogenes BRAF and NRas are the most common genetic alterations in cutaneous melanoma. Still, the nanoscale organization and signal coupling of these proteins remain incompletely understood, particularly upon expression of oncogenic NRas mutants. Here we employed single-molecule localization microscopy to study the nanoscale organization of NRas and BRAF at the plasma membrane (PM) of melanoma cells. NRas and BRAF resided in self-clusters that did not associate well in resting cells. In EGF-activated cells, NRas clusters became more diffused while overall protein levels at the PM increased; thus allowing enhanced association of NRas and BRAF and downstream signaling. In multiple melanoma cell lines, mutant NRas resided in more pronounced self-clusters relative to wild-type (WT) NRas yet associated more with the clustered and more abundant BRAF. In cells resistant to trametinib, a clinical MEK inhibitor (MEKi), a similar coclustering of NRas and BRAF was observed upon EGF activation. Strikingly, treatment of cells expressing mutant NRas with trametinib reversed the effect of mutant NRas expression by restoring the nonoverlapping self-clusters of NRas and BRAF and by reducing their PM levels and elevated pERK levels caused by mutant NRas. Our results indicate a new mechanism for signal regulation of NRas in melanoma through its nanoscale dynamic organization and a new mechanism for MEKi function in melanoma cells carrying NRas mutations but lacking MEK mutations. SIGNIFICANCE: Nanoscale dynamic organization of WT and mutant NRas relative to BRAF serves as a regulatory mechanism for NRas signaling and may be a viable therapeutic target for its sensitivity to MEKi.
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Affiliation(s)
- Oren Yakovian
- Racah Institute of Physics, The Hebrew University, Jerusalem, Israel
| | - Julia Sajman
- Racah Institute of Physics, The Hebrew University, Jerusalem, Israel
| | - Rand Arafeh
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Yair Neve-Oz
- Racah Institute of Physics, The Hebrew University, Jerusalem, Israel
| | - Michal Alon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Yardena Samuels
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Eilon Sherman
- Racah Institute of Physics, The Hebrew University, Jerusalem, Israel.
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19
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Andrian T, Bakkum T, van Elsland DM, Bos E, Koster AJ, Albertazzi L, van Kasteren SI, Pujals S. Super-resolution correlative light-electron microscopy using a click-chemistry approach for studying intracellular trafficking. Methods Cell Biol 2020; 162:303-331. [PMID: 33707017 DOI: 10.1016/bs.mcb.2020.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Correlative light and electron microscopy (CLEM) entails a group of multimodal imaging techniques that are combined to pinpoint to the location of fluorescently labeled molecules in the context of their ultrastructural cellular environment. Here we describe a detailed workflow for STORM-CLEM, in which STochastic Optical Reconstruction Microscopy (STORM), an optical super-resolution technique, is correlated with transmission electron microscopy (TEM). This protocol has the advantage that both imaging modalities have resolution at the nanoscale, bringing higher synergies on the information obtained. The sample is prepared according to the Tokuyasu method followed by click-chemistry labeling and STORM imaging. Then, after heavy metal staining, electron microscopy imaging is performed followed by correlation of the two images. The case study presented here is on intracellular pathogens, but the protocol is versatile and could potentially be applied to many types of samples.
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Affiliation(s)
- Teodora Andrian
- Institute of Bioengineering of Catalonia (IBEC), Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Thomas Bakkum
- Leiden Institute of Chemistry and The Institute for Chemical Immunology, Leiden University, Leiden, The Netherlands
| | - Daphne M van Elsland
- Department of Cell and Chemical Biology, The Institute for Chemical Immunology, Leiden University Medical Center LUMC, Leiden, The Netherlands
| | - Erik Bos
- Department of Cell and Chemical Biology, Section Electron Microscopy, Leiden University Medical Center LUMC, Leiden, The Netherlands
| | - Abraham J Koster
- Department of Cell and Chemical Biology, Section Electron Microscopy, Leiden University Medical Center LUMC, Leiden, The Netherlands
| | - Lorenzo Albertazzi
- Institute of Bioengineering of Catalonia (IBEC), Barcelona Institute of Science and Technology, Barcelona, Spain; Department of Biomedical Engineering, Institute of Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands.
| | - Sander I van Kasteren
- Leiden Institute of Chemistry and The Institute for Chemical Immunology, Leiden University, Leiden, The Netherlands.
| | - Sílvia Pujals
- Institute of Bioengineering of Catalonia (IBEC), Barcelona Institute of Science and Technology, Barcelona, Spain; Department of Electronics and Biomedical Engineering, Faculty of Physics, Universitat de Barcelona, Barcelona, Spain.
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20
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Webster P, Saito K, Cortez J, Ramirez C, Baum MM. Concentrative Nucleoside Transporter 3 Is Located on Microvilli of Vaginal Epithelial Cells. ACS OMEGA 2020; 5:20882-20889. [PMID: 32875223 PMCID: PMC7450627 DOI: 10.1021/acsomega.0c02329] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 07/29/2020] [Indexed: 06/11/2023]
Abstract
Transporters are specialized integral membrane proteins, which mediate the passage of virtually all molecules through cell membranes. They are expressed in a broad range of human and animal tissues and play important roles in both normal and disease states. For these reasons, they are evaluated when developing and testing drugs. Two major families of drug transporters, the adenosine 5'-triphosphate-binding cassette and solute carrier transporters (SLC), have critical roles in the absorption, distribution, metabolism, and elimination of drugs. The SLC family contains known nucleoside transporters and therefore are important when nucleoside analogs are used as drugs to prevent or treat viral infections. In this study, we wanted to determine if it was possible to locate one member of the SLC family, the human concentrative nucleoside transporter 3 (CNT3) in human vaginal epithelial cells. The CNT3 protein has important roles in drug delivery, subsequent drug tissue distribution, and, hence, efficacy. Vaginal epithelial cells, taken from two human volunteers (one Caucasian and one African American), were labeled for light and electron microscopy, with a commercial antibody to a cytoplasmic domain of CNT3, the protein product of the SLC28A3 gene. Fluorescent secondary antibodies or protein A-gold were used to detect antibody binding. By electron microscopy, gold particle binding was quantified to determine labeling specificity. By light microscopy, positive labeling with anti-CNT3 antibodies was detected on human vaginal epithelial cells, but specificity to any intracellular structure was not easily determined, most likely a result of specimen preparation. Electron microscopy revealed that the CNT3 transporter protein was present predominantly on microvilli located on one side of some human vaginal epithelial cells. Quantification confirmed specific anti-CNT3 labeling over human vaginal epithelial cell microvilli. The CNT3 protein, present in the microvilli of human vaginal epithelial cells, may have a role in redistributing nucleoside homologues delivered to the vaginal tract. Transporter proteins such as CNT3 could shuttle nucleosides and their analogs through the vaginal epithelium to immune cells located in lower cell layers. Outer layers of cells, which are eventually shed from the epithelium, may remove accumulated nucleoside drug analogs from the vaginal tract.
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Affiliation(s)
- Paul Webster
- Oak
Crest Institute of Science, 132 W. Chestnut Avenue, Monrovia, California 91016, United States
| | - Kaori Saito
- Oak
Crest Institute of Science, 132 W. Chestnut Avenue, Monrovia, California 91016, United States
| | - John Cortez
- Oak
Crest Institute of Science, 132 W. Chestnut Avenue, Monrovia, California 91016, United States
| | - Christina Ramirez
- Los
Angeles (UCLA) Fielding School of Public Health, University of California, Los Angeles, 650 Charles E. Young Dr. South, 16-035 Center for
Health Sciences, Los Angeles, California 90095-1772, United States
| | - Marc M. Baum
- Oak
Crest Institute of Science, 132 W. Chestnut Avenue, Monrovia, California 91016, United States
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21
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Localization of ZIP14 and ZIP8 in HIBCPP Cells. Brain Sci 2020; 10:brainsci10080534. [PMID: 32784388 PMCID: PMC7464652 DOI: 10.3390/brainsci10080534] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/05/2020] [Accepted: 08/06/2020] [Indexed: 12/20/2022] Open
Abstract
The blood-cerebrospinal fluid barrier (BCB) is important in maintaining brain manganese (Mn) homeostasis. This barrier consists of a single layer of epithelial cells, connected by tight junctions, that restrict the passage of nutrients to only allow molecules to be carried through the membrane by a transporter. These epithelial cells are polarized with asymmetrical blood-facing and cerebrospinal fluid-facing sides. Here, we have established a polarized model of a human choroid plexus papilloma cell line, HIBCPP. For the first time, Mn importers ZIP14 and ZIP8 were identified in HIBCPP cells and were found to be enriched at the basolateral and apical sides of the cell monolayer, respectively. The localization of each ZIP protein adds to the understanding of Mn transport across the HIBCPP BCB model to help understand the mechanism of Mn homeostasis within the brain.
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22
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Franke C, Repnik U, Segeletz S, Brouilly N, Kalaidzidis Y, Verbavatz JM, Zerial M. Correlative single-molecule localization microscopy and electron tomography reveals endosome nanoscale domains. Traffic 2020; 20:601-617. [PMID: 31206952 PMCID: PMC6771687 DOI: 10.1111/tra.12671] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 06/04/2019] [Accepted: 06/09/2019] [Indexed: 12/12/2022]
Abstract
Many cellular organelles, including endosomes, show compartmentalization into distinct functional domains, which, however, cannot be resolved by diffraction‐limited light microscopy. Single molecule localization microscopy (SMLM) offers nanoscale resolution but data interpretation is often inconclusive when the ultrastructural context is missing. Correlative light electron microscopy (CLEM) combining SMLM with electron microscopy (EM) enables correlation of functional subdomains of organelles in relation to their underlying ultrastructure at nanometer resolution. However, the specific demands for EM sample preparation and the requirements for fluorescent single‐molecule photo‐switching are opposed. Here, we developed a novel superCLEM workflow that combines triple‐color SMLM (dSTORM & PALM) and electron tomography using semi‐thin Tokuyasu thawed cryosections. We applied the superCLEM approach to directly visualize nanoscale compartmentalization of endosomes in HeLa cells. Internalized, fluorescently labeled Transferrin and EGF were resolved into morphologically distinct domains within the same endosome. We found that the small GTPase Rab5 is organized in nanodomains on the globular part of early endosomes. The simultaneous visualization of several proteins in functionally distinct endosomal sub‐compartments demonstrates the potential of superCLEM to link the ultrastructure of organelles with their molecular organization at nanoscale resolution.
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Affiliation(s)
- Christian Franke
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Urska Repnik
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Sandra Segeletz
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Nicolas Brouilly
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Instutut de Biologie du Developpement de Marseille-Luminy, Aix-Marseille Universite, Marseille, France
| | - Yannis Kalaidzidis
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Faculty of Bioengineering and Bioinformatics, Moscow State University, Moscow, Russia
| | - Jean-Marc Verbavatz
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Institut Jacques Monod, CNRS, Université Paris-Diderot, Paris, France
| | - Marino Zerial
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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23
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Begemann I, Keller U, Nüsse H, Klingauf J, Galic M. Parallel Acquisition of Plasma Membrane Ultrastructure and Cytosolic Protein Localisation in Cultured Cells via Correlated Immunogold SEM. Cells 2020; 9:cells9061329. [PMID: 32466457 PMCID: PMC7349049 DOI: 10.3390/cells9061329] [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: 04/01/2020] [Revised: 05/06/2020] [Accepted: 05/14/2020] [Indexed: 11/16/2022] Open
Abstract
Scanning electron microscopy (SEM) takes advantage of distinct detectors to visualise secondary and back-scattering electrons. Here, we report an integrated approach that relies on these two detection methods to simultaneously acquire correlated information on plasma membrane topography and curvature-sensitive cytosolic protein localization in intact cell samples. We further provide detailed preparation and staining protocols, as well as a thorough example-based discussion for imaging optimisation. Collectively, the presented method enables rapid and precise analysis of cytosolic proteins adjacent to cellular membranes with a resolution of ~100 nm, without time-consuming preparations or errors induced by sequential visualisation present in fluorescence-based correlative approaches.
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Affiliation(s)
- Isabell Begemann
- Institute of Medical Physics and Biophysics, University of Muenster, Robert-Koch-Str. 31, 48149 Münster, Germany; (I.B.); (U.K.); (H.N.); (J.K.)
- Interfaculty Centre ‘Cells in Motion’, University of Muenster, Waldeyerstr. 15, 48149 Münster, Germany
| | - Ulrike Keller
- Institute of Medical Physics and Biophysics, University of Muenster, Robert-Koch-Str. 31, 48149 Münster, Germany; (I.B.); (U.K.); (H.N.); (J.K.)
| | - Harald Nüsse
- Institute of Medical Physics and Biophysics, University of Muenster, Robert-Koch-Str. 31, 48149 Münster, Germany; (I.B.); (U.K.); (H.N.); (J.K.)
| | - Jürgen Klingauf
- Institute of Medical Physics and Biophysics, University of Muenster, Robert-Koch-Str. 31, 48149 Münster, Germany; (I.B.); (U.K.); (H.N.); (J.K.)
- Interfaculty Centre ‘Cells in Motion’, University of Muenster, Waldeyerstr. 15, 48149 Münster, Germany
| | - Milos Galic
- Institute of Medical Physics and Biophysics, University of Muenster, Robert-Koch-Str. 31, 48149 Münster, Germany; (I.B.); (U.K.); (H.N.); (J.K.)
- Interfaculty Centre ‘Cells in Motion’, University of Muenster, Waldeyerstr. 15, 48149 Münster, Germany
- Correspondence:
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24
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Ulloa-Navas MJ, García-Tárraga P, García-Verdugo JM, Herranz-Pérez V. Immunogold Labeling to Detect Streptococcus pyogenes Cas9 in Cell Culture and Tissues by Electron Microscopy. CRISPR J 2019; 2:395-405. [PMID: 31860352 DOI: 10.1089/crispr.2019.0032] [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: 11/13/2022] Open
Abstract
The CRISPR-Cas9 system is a powerful and yet precise DNA-editing tool in rapid development. By combining immunogold labeling and electron microscopy with the novel CRISPR-Cas9 system, we propose a new method to gain insight into the biology of this tool. In this study, we analyzed different Cas9-induced systems such as HEK293T cell line, murine oligodendrocyte progenitor cells, brain and liver to detect Cas9 expression by immunoelectron microscopy. Our results show that while Cas9 expression could be found in the nuclei and nucleopores of transfected HEK293T cells, in transfected oligodendrocyte precursor cells, Cas9 was found in cytoplasmic vesicles. In Cas9 constitutively expressing oligodendrocyte precursors, the enzyme was located in the cytoplasm of nondividing cells. Finally, while in the liver Cas9 was detected in different cell types, in the brain we found no specifically labeled cells. In conclusion, immunoelectron microscopy opens a new spectrum of opportunities to study the CRISPR-Cas9 system in a more precise manner.
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Affiliation(s)
- María José Ulloa-Navas
- Laboratory of Comparative Neurobiology, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, CIBERNED, Paterna, Spain; and Faculty of Health Sciences, University Jaume I, Castelló de la Plana, Spain
| | - Patricia García-Tárraga
- Laboratory of Comparative Neurobiology, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, CIBERNED, Paterna, Spain; and Faculty of Health Sciences, University Jaume I, Castelló de la Plana, Spain
| | - José Manuel García-Verdugo
- Laboratory of Comparative Neurobiology, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, CIBERNED, Paterna, Spain; and Faculty of Health Sciences, University Jaume I, Castelló de la Plana, Spain
| | - Vicente Herranz-Pérez
- Laboratory of Comparative Neurobiology, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, CIBERNED, Paterna, Spain; and Faculty of Health Sciences, University Jaume I, Castelló de la Plana, Spain
- Predepartamental Unit of Medicine, Faculty of Health Sciences, University Jaume I, Castelló de la Plana, Spain
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25
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Doh JK, Tobin SJ, Beatty KE. Generation of CoilR Probe Peptides for VIPER-labeling of Cellular Proteins. Bio Protoc 2019; 9:e3412. [PMID: 33654912 PMCID: PMC7853930 DOI: 10.21769/bioprotoc.3412] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 09/24/2019] [Accepted: 09/30/2019] [Indexed: 11/02/2022] Open
Abstract
Versatile Interacting Peptide (VIP) tags are a new class of genetically-encoded tag designed for imaging cellular proteins by fluorescence and electron microscopy. In 2018, we reported the VIPER tag ( Doh et al., 2018 ), which contains two elements: a genetically-encoded peptide tag (i.e., CoilE) and a probe peptide (i.e., CoilR). These two peptides deliver contrast to a protein of interest by forming a specific, high-affinity heterodimer. The probe peptide was designed with a single cysteine residue for site-specific modification via thiol-maleimide chemistry. This feature can be used to attach a variety of biophysical reporters to the peptide, including bright fluorophores for fluorescence microscopy or electron-dense nanoparticles for electron microscopy. In this Bio-Protocol, we describe our methods for expressing and purifying recombinant CoilR. Additionally, we describe protocols for making fluorescent or biotinylated probe peptides for labeling CoilE-tagged cellular proteins. This protocol is complemented by two other Bio-Protocols outlining the use of VIPER ( Doh et al., 2019a and 2019b).
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Affiliation(s)
- Julia K. Doh
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Savannah J. Tobin
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Kimberly E. Beatty
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon 97239, USA
- OHSU Center for Spatial Systems Biomedicine, Oregon Health & Science University, Portland, Oregon 97239, USA
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26
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Chemical Fixation, Immunofluorescence, and Immunogold Labeling of Electron Microscopical Sections. Methods Mol Biol 2019. [PMID: 31148030 DOI: 10.1007/978-1-4939-9469-4_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Knowledge about the spatiotemporal distribution patterns of proteins and other molecules of the cell is essential for understanding their function. A widely used technique is immunolabeling which uses specific antibodies to reveal the distribution of molecular components at various structural levels. Immunofluorescence gives an overview about the distribution of molecules at the level of the fluorescence or confocal laser scanning microscope. Electron microscopy offers the highest resolution of morphological techniques and is thus an indispensable tool for the analysis of molecule distribution patterns at the subcellular level. In this chapter we describe selected routine methods for immunofluorescence and for labeling ultrathin sections of resin-embedded material with antibodies conjugated to colloidal gold, including protocols for chemical fixation, embedding, and sectioning.
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27
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D’Brant LY, Desta H, Khoo TC, Sharikova AV, Mahajan SD, Khmaladze A. Methamphetamine-induced apoptosis in glial cells examined under marker-free imaging modalities. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-10. [PMID: 31025559 PMCID: PMC6990058 DOI: 10.1117/1.jbo.24.4.046503] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 04/05/2019] [Indexed: 05/05/2023]
Abstract
We used phase microscopy and Raman spectroscopic measurements to assess the response of in vitro rat C6 glial cells following methamphetamine treatment in real time. Digital holographic microscopy (DHM) and three-dimensional (3-D) tomographic nanoscopy allow measurements of live cell cultures, which yield information about cell volume changes. Tomographic phase imaging provides 3-D information about the refractive index distribution associated with the morphology of biological samples. DHM provides similar information, but for a larger population of cells. Morphological changes in cells are associated with alterations in cell cycle and initiation of cell death mechanisms. Raman spectroscopy measurements provide information about chemical changes within the cells. Our Raman data indicate that the chemical changes in proteins preceded morphological changes, which were seen with DHM. Our study also emphasizes that tomographic phase imaging, DHM, and Raman spectroscopy are imaging tools that can be utilized for noninvasive simultaneous monitoring of morphological and chemical changes in cells during apoptosis and can also be used to monitor other dynamic cell processes.
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Affiliation(s)
- Lianna Y. D’Brant
- State University of New York System (SUNY), Albany, New York, United States
| | - Habben Desta
- State University of New York System (SUNY), Albany, New York, United States
| | - Ting Chean Khoo
- State University of New York System (SUNY), Albany, New York, United States
| | - Anna V. Sharikova
- State University of New York, Jacobs School of Medicine & Biomedical Sciences, Buffalo, New York, United States
| | - Supriya D. Mahajan
- State University of New York System (SUNY), Albany, New York, United States
| | - Alexander Khmaladze
- State University of New York System (SUNY), Albany, New York, United States
- Address all correspondence to Alexander Khmaladze, E-mail:
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Richert-Pöggeler KR, Franzke K, Hipp K, Kleespies RG. Electron Microscopy Methods for Virus Diagnosis and High Resolution Analysis of Viruses. Front Microbiol 2019; 9:3255. [PMID: 30666247 PMCID: PMC6330349 DOI: 10.3389/fmicb.2018.03255] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 12/14/2018] [Indexed: 01/29/2023] Open
Abstract
The term "virosphere" describes both the space where viruses are found and the space they influence, and can extend to their impact on the environment, highlighting the complexity of the interactions involved. Studying the biology of viruses and the etiology of virus disease is crucial to the prevention of viral disease, efficient and reliable virus diagnosis, and virus control. Electron microscopy (EM) is an essential tool in the detection and analysis of virus replication. New EM methods and ongoing technical improvements offer a broad spectrum of applications, allowing in-depth investigation of viral impact on not only the host but also the environment. Indeed, using the most up-to-date electron cryomicroscopy methods, such investigations are now close to atomic resolution. In combination with bioinformatics, the transition from 2D imaging to 3D remodeling allows structural and functional analyses that extend and augment our knowledge of the astonishing diversity in virus structure and lifestyle. In combination with confocal laser scanning microscopy, EM enables live imaging of cells and tissues with high-resolution analysis. Here, we describe the pivotal role played by EM in the study of viruses, from structural analysis to the biological relevance of the viral metagenome (virome).
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Affiliation(s)
- Katja R. Richert-Pöggeler
- Federal Research Center for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn Institute, Braunschweig, Germany
| | - Kati Franzke
- Institute of Infectiology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Katharina Hipp
- Electron Microscopy Facility, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Regina G. Kleespies
- Federal Research Centre for Cultivated Plants, Institute for Biological Control, Julius Kühn Institute, Darmstadt, Germany
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29
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Liu M, Heimlicher MB, Bächler M, Ibeneche-Nnewihe CC, Florin EL, Brunner D, Hoenger A. Glucose starvation triggers filamentous septin assemblies in an S. pombe septin-2 deletion mutant. Biol Open 2019; 8:8/1/bio037622. [PMID: 30602528 PMCID: PMC6361201 DOI: 10.1242/bio.037622] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Using correlative light and electron microscopy (CLEM), we studied the intracellular organization by of glucose-starved fission yeast cells (Schizosaccharomyces pombe) with regards to the localization of septin proteins throughout the cytoplasm. Thereby, we found that for cells carrying a deletion of the gene encoding septin-2 (spn2Δ), starvation causes a GFP-tagged version of septin-3 (spn3-GFP) and family members, to assemble into a single, prominent filamentous structure. It was previously shown that during exponential growth, spn2Δ cells form septin-3 polymers. However, the polymers we observed during exponential growth are different from the spn3p-GFP structure we observed in starved cells. Using CLEM, in combination with anti-GFP immunolabeling on plastic-sections, we could assign spn3p-GFP to the filaments we have found in EM pictures. Besides septin-3, these filamentous assemblies most likely also contain septin-1 as an RFP-tagged version of this protein forms a very similar structure in starved spn2Δ cells. Our data correlate phase-contrast and fluorescence microscopy with electron micrographs of plastic-embedded cells, and further on with detailed views of tomographic 3D reconstructions. Cryo-electron microscopy of spn2Δ cells in vitrified sections revealed a very distinct overall morphology of the spn3p-GFP assembly. The fine-structured, regular density pattern suggests the presence of assembled septin-3 filaments that are clearly different from F-actin bundles. Furthermore, we found that starvation causes substantial mitochondria fission, together with massive decoration of their outer membrane by ribosomes.
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Affiliation(s)
- Minghua Liu
- University of Colorado at Boulder, Department of Molecular, Cellular and Developmental Biology, UCB-0347, Boulder, CO 80309, USA
| | - Maria B Heimlicher
- University of Zürich, Department of Molecular Life Sciences, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Mirjam Bächler
- University of Zürich, Department of Molecular Life Sciences, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Chieze C Ibeneche-Nnewihe
- University of Texas at Austin, Center for Nonlinear Dynamics and Department of Physics, Austin, TX 78712, USA
| | - Ernst-Ludwig Florin
- University of Texas at Austin, Center for Nonlinear Dynamics and Department of Physics, Austin, TX 78712, USA
| | - Damian Brunner
- University of Zürich, Department of Molecular Life Sciences, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Andreas Hoenger
- University of Colorado at Boulder, Department of Molecular, Cellular and Developmental Biology, UCB-0347, Boulder, CO 80309, USA
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30
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Weil MT, Ruhwedel T, Meschkat M, Sadowski B, Möbius W. Transmission Electron Microscopy of Oligodendrocytes and Myelin. Methods Mol Biol 2019; 1936:343-375. [PMID: 30820909 DOI: 10.1007/978-1-4939-9072-6_20] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In this chapter, we describe protocols to study different aspects of oligodendrocytes and myelin using electron microscopy. First, we describe in detail how to prepare central nervous system tissue routinely by perfusion fixation of the animal and conventional embedding in Epon resin. Then, we explain how, with some modifications, chemically fixed tissue can be used for immunoelectron microscopy on cryosections. Chemical fixation and Epon embedding can also be applied to purified myelin to assess the quality of the preparation. Furthermore, we describe how cryopreparation by high-pressure freezing can be used to study the fine structure of myelin in nerve, brain, and spinal cord tissue. The differences in the structural appearance of oligodendrocytes and myelin between cryopreserved and conventionally processed samples are compared using representative images. Since primary cultured oligodendrocytes are used to study structure and function in vitro, we provide protocols for chemical fixation and Epon embedding of these cultures. Finally, we explain how the cytoskeleton of cultured oligodendrocytes can be visualized by using transmission electron microscopy on platinum-carbon replicas. In this chapter, we provide a wide range of protocols that can be applied to shed light on the different biological aspects of myelin and oligodendrocytes.
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Affiliation(s)
- Marie-Theres Weil
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Electron Microscopy Core Unit, Göttingen, Germany.,Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany.,AbbVie Deutschland GmbH and Co. KG, Ludwigshafen, Germany
| | - Torben Ruhwedel
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Electron Microscopy Core Unit, Göttingen, Germany
| | - Martin Meschkat
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Electron Microscopy Core Unit, Göttingen, Germany
| | - Boguslawa Sadowski
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Electron Microscopy Core Unit, Göttingen, Germany.,Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Wiebke Möbius
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Electron Microscopy Core Unit, Göttingen, Germany. .,Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany.
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31
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Taatjes DJ, Roth J. In focus in HCB. Histochem Cell Biol 2018; 151:1-3. [PMID: 30560288 DOI: 10.1007/s00418-018-1762-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2018] [Indexed: 11/28/2022]
Affiliation(s)
- Douglas J Taatjes
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, VT, 05405, USA.
| | - Jürgen Roth
- University of Zurich, 8091, Zurich, Switzerland
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VIPER is a genetically encoded peptide tag for fluorescence and electron microscopy. Proc Natl Acad Sci U S A 2018; 115:12961-12966. [PMID: 30518560 DOI: 10.1073/pnas.1808626115] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many discoveries in cell biology rely on making specific proteins visible within their native cellular environment. There are various genetically encoded tags, such as fluorescent proteins, developed for fluorescence microscopy (FM). However, there are almost no genetically encoded tags that enable cellular proteins to be observed by both FM and electron microscopy (EM). Herein, we describe a technology for labeling proteins with diverse chemical reporters, including bright organic fluorophores for FM and electron-dense nanoparticles for EM. Our technology uses versatile interacting peptide (VIP) tags, a class of genetically encoded tag. We present VIPER, which consists of a coiled-coil heterodimer formed between the genetic tag, CoilE, and a probe-labeled peptide, CoilR. Using confocal FM, we demonstrate that VIPER can be used to highlight subcellular structures or to image receptor-mediated iron uptake. Additionally, we used VIPER to image the iron uptake machinery by correlative light and EM (CLEM). VIPER compared favorably with immunolabeling for imaging proteins by CLEM, and is an enabling technology for protein targets that cannot be immunolabeled. VIPER is a versatile peptide tag that can be used to label and track proteins with diverse chemical reporters observable by both FM and EM instrumentation.
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Möbius W, Posthuma G. Sugar and ice: Immunoelectron microscopy using cryosections according to the Tokuyasu method. Tissue Cell 2018; 57:90-102. [PMID: 30201442 DOI: 10.1016/j.tice.2018.08.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 07/26/2018] [Accepted: 08/22/2018] [Indexed: 11/29/2022]
Abstract
Since the pioneering work of Kiyoteru Tokuyasu in the 70ths the use of thawed cryosections prepared according to the "Tokuyasu-method" for immunoelectron microscopy did not lose popularity. We owe this method a whole subcellular world described by discrete gold particles pointing at cargo, receptors and organelle markers on delicate images of the inner life of a cell. Here we explain the procedure of sample preparation, sectioning and immunolabeling in view of recent developments and the reasoning behind protocols including some historical perspective. Cryosections are prepared from chemically fixed and sucrose infiltrated samples and labeled with affinity probes and electron dense markers. These sections are ideal substrates for immunolabeling, since antigens are not exposed to organic solvent dehydration or masked by resin. Instead, the structures remain fully hydrated throughout the labeling procedure. Furthermore, target molecules inside dense intercellular structural elements, cells and organelles are accessible to antibodies from the section surface. For the validation of antibody specificity several approaches are recommended including knock-out tissue and reagent controls. Correlative light and electron microscopy strategies involving correlative probes are possible as well as correlation of live imaging with the underlying ultrastructure. By applying stereology, gold labeling can be quantified and evaluated for specificity.
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Affiliation(s)
- Wiebke Möbius
- Electron Microscopy Core Unit, Department of Neurogenetics, Max Planck Institute of Experimental Medicine, 37075, Göttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Göttingen, Germany.
| | - George Posthuma
- Department of Cell Biology, Cell Microscopy Core, University Medical Center Utrecht, Utrecht University, P.O. Box 85500, 3508 GA, Utrecht, The Netherlands.
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34
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Zhou X, Rickmann M, Hafner G, Staiger JF. Subcellular Targeting of VIP Boutons in Mouse Barrel Cortex is Layer-Dependent and not Restricted to Interneurons. Cereb Cortex 2018; 27:5353-5368. [PMID: 28968722 PMCID: PMC6084601 DOI: 10.1093/cercor/bhx220] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 08/02/2017] [Indexed: 12/22/2022] Open
Abstract
Neocortical vasoactive intestinal polypeptide (VIP) expressing cells are a diverse subpopulation of GABAergic interneurons issuing distinct axonal projections. They are known to inhibit other types of interneurons as well as excitatory principal neurons and possess a disinhibitory net effect in cortical circuits. In order to elucidate their targeting specificity, the output connectivity of VIP interneurons was studied at the subcellular level in barrel cortex of interneuron-specific Cre-driver mice, using pre- and postembedding electron microscopy. Systematically sampling VIP boutons across all layers, we found a substantial proportion of the innervated subcellular structures were dendrites (80%), with somata (13%), and spines (7%) being much less targeted. In layer VI, a high proportion of axosomatic synapses was found (39%). GABA-immunopositive ratio was quantified among the targets using statistically validated thresholds: only 37% of the dendrites, 7% of the spines, and 26% of the somata showed above-threshold immunogold labeling. For the main target structure "dendrite", a higher proportion of GABAergic subcellular profiles existed in deep than in superficial layers. In conclusion, VIP interneurons innervate non-GABAergic excitatory neurons and interneurons at their subcellular domains with layer-dependent specificity. This suggests a diverse output of VIP interneurons, which predicts multiple functionality in cortical circuitry beyond disinhibition.
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Affiliation(s)
- Xiaojuan Zhou
- Institute for Neuroanatomy,University Medicine Göttingen, Georg-August-University, Kreuzbergring 36, D-37075 Göttingen, Germany
| | - Michael Rickmann
- Institute for Neuroanatomy,University Medicine Göttingen, Georg-August-University, Kreuzbergring 36, D-37075 Göttingen, Germany
| | - Georg Hafner
- Institute for Neuroanatomy,University Medicine Göttingen, Georg-August-University, Kreuzbergring 36, D-37075 Göttingen, Germany
| | - Jochen F Staiger
- Institute for Neuroanatomy,University Medicine Göttingen, Georg-August-University, Kreuzbergring 36, D-37075 Göttingen, Germany
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Richert-Pöggeler KR, Franzke K, Hipp K, Kleespies RG. Electron Microscopy Methods for Virus Diagnosis and High Resolution Analysis of Viruses. Front Microbiol 2018. [PMID: 30666247 DOI: 10.3389/fmicb.2018.03255.ecollection] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023] Open
Abstract
The term "virosphere" describes both the space where viruses are found and the space they influence, and can extend to their impact on the environment, highlighting the complexity of the interactions involved. Studying the biology of viruses and the etiology of virus disease is crucial to the prevention of viral disease, efficient and reliable virus diagnosis, and virus control. Electron microscopy (EM) is an essential tool in the detection and analysis of virus replication. New EM methods and ongoing technical improvements offer a broad spectrum of applications, allowing in-depth investigation of viral impact on not only the host but also the environment. Indeed, using the most up-to-date electron cryomicroscopy methods, such investigations are now close to atomic resolution. In combination with bioinformatics, the transition from 2D imaging to 3D remodeling allows structural and functional analyses that extend and augment our knowledge of the astonishing diversity in virus structure and lifestyle. In combination with confocal laser scanning microscopy, EM enables live imaging of cells and tissues with high-resolution analysis. Here, we describe the pivotal role played by EM in the study of viruses, from structural analysis to the biological relevance of the viral metagenome (virome).
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Affiliation(s)
- Katja R Richert-Pöggeler
- Federal Research Center for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn Institute, Braunschweig, Germany
| | - Kati Franzke
- Institute of Infectiology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Katharina Hipp
- Electron Microscopy Facility, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Regina G Kleespies
- Federal Research Centre for Cultivated Plants, Institute for Biological Control, Julius Kühn Institute, Darmstadt, Germany
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36
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UDP-sugars activate P2Y 14 receptors to mediate vasoconstriction of the porcine coronary artery. Vascul Pharmacol 2017; 103-105:36-46. [PMID: 29253618 PMCID: PMC5906693 DOI: 10.1016/j.vph.2017.12.063] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 12/04/2017] [Accepted: 12/12/2017] [Indexed: 12/19/2022]
Abstract
Aims UDP-sugars can act as extracellular signalling molecules, but relatively little is known about their cardiovascular actions. The P2Y14 receptor is a Gi/o-coupled receptor which is activated by UDP-glucose and related sugar nucleotides. In this study we sought to investigate whether P2Y14 receptors are functionally expressed in the porcine coronary artery using a selective P2Y14 receptor agonist, MRS2690, and a novel selective P2Y14 receptor antagonist, PPTN (4,7-disubstituted naphthoic acid derivative). Methods and results Isometric tension recordings were used to evaluate the effects of UDP-sugars in porcine isolated coronary artery segments. The effects of the P2 receptor antagonists suramin and PPADS, the P2Y14 receptor antagonist PPTN, and the P2Y6 receptor antagonist MRS2578, were investigated. Measurement of vasodilator-stimulated phosphoprotein (VASP) phosphorylation using flow cytometry was used to assess changes in cAMP levels. UDP-glucose, UDP-glucuronic acid UDP-N-acetylglucosamine (P2Y14 receptor agonists), elicited concentration-dependent contractions of the porcine coronary artery. MRS2690 was a more potent vasoconstrictor than the UDP-sugars. Concentration dependent contractile responses to MRS2690 and UDP-sugars were enhanced in the presence of forskolin (activator of cAMP), where the level of basal tone was maintained by addition of U46619, a thromboxane A2 mimetic. Contractile responses to MRS2690 were blocked by PPTN, but not by MRS2578. Contractile responses to UDP-glucose were also attenuated by PPTN and suramin, but not by MRS2578. Forskolin-induced VASP-phosphorylation was reduced in porcine coronary arteries exposed to UDP-glucose and MRS2690, consistent with P2Y14 receptor coupling to Gi/o proteins and inhibition of adenylyl cyclase activity. Conclusions Our data support a role of UDP-sugars as extracellular signalling molecules and show for the first time that they mediate contraction of porcine coronary arteries via P2Y14 receptors.
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Zupančič D, Terčelj M, Štrus B, Veranič P. How to obtain good morphology and antigen detection in the same tissue section? PROTOPLASMA 2017; 254:1931-1939. [PMID: 28188396 DOI: 10.1007/s00709-017-1085-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 01/31/2017] [Indexed: 06/06/2023]
Abstract
Most human and animal biopsy samples are routinely embedded in paraffin since this enables the pathologist or researcher to obtain excellent morphology and simplifies storage. Nevertheless, in many cases, the antigen of interest cannot be detected in paraffin section. The alternative available for good immunohistochemistry is preparation of cryosections, which usually provide decent antigen preservation and are frequently used for immunofluorescence. However, cryosections often do not provide efficient morphological details of tissues and cells for pathologic evaluation. In order to obtain good antigen preservation and improve tissue and cell morphology after freezing, we tested three different fixations and freezing methodologies and compared them to routine formaldehyde fixation and paraffin embedding. As a model system, we selected the epithelium of the rat urinary bladder and trachea. On all samples, haematoxylin and eosin staining was performed as well as immunofluorescence with antibodies against tight junction protein ZO-1 and against intermediate filament cytokeratin 7. The best compromise between morphology and immunofluorescence was obtained with "sucrose impregnation prior to freezing" method. Moreover, this procedure is also quicker in comparison to standard paraffin section preparation. To check the clinical relevance of our study, this method was used for human biopsy samples of neoplastic urothelial and bronchial mucosa lesions. Besides good immunofluorescence results, the morphology of these samples was well preserved. We therefore propose that cryosection preparation with sucrose impregnation prior to freezing should be further exploited in other clinical and veterinary applications, since it enables good morphology and antigen preservation.
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Affiliation(s)
- Daša Zupančič
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia.
| | - Marjeta Terčelj
- Department of Pulmonary and Allergic Diseases, University Medical Centre Ljubljana, Zaloška cesta 2, 1000, Ljubljana, Slovenia
| | - Bojan Štrus
- Department of Urology, University Medical Centre Ljubljana, Zaloška cesta 2, 1000, Ljubljana, Slovenia
| | - Peter Veranič
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia
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Tools and limitations to study the molecular composition of synapses by fluorescence microscopy. Biochem J 2017; 473:3385-3399. [PMID: 27729584 DOI: 10.1042/bcj20160366] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/23/2016] [Indexed: 01/21/2023]
Abstract
The synapse is densely packed with proteins involved in various highly regulated processes. Synaptic protein copy numbers and their stoichiometric distribution have a drastic influence on neuronal integrity and function. Therefore, the molecular analysis of synapses is a key element to understand their architecture and function. The overall structure of the synapse has been revealed with an exquisite amount of details by electron microscopy. However, the molecular composition and the localization of proteins are more easily addressed with fluorescence imaging, especially with the improved resolution achieved by super-resolution microscopy techniques. Notably, the fast improvement of imaging instruments has not been reflected in the optimization of biological sample preparation. During recent years, large efforts have been made to generate affinity probes smaller than conventional antibodies adapted for fluorescent super-resolution imaging. In this review, we briefly discuss the current views on synaptic organization and necessary key technologies to progress in the understanding of synaptic physiology. We also highlight the challenges faced by current fluorescent super-resolution methods, and we describe the prerequisites for an ideal study of synaptic organization.
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Ochs M, Knudsen L, Hegermann J, Wrede C, Grothausmann R, Mühlfeld C. Using electron microscopes to look into the lung. Histochem Cell Biol 2016; 146:695-707. [PMID: 27688057 DOI: 10.1007/s00418-016-1502-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2016] [Indexed: 02/06/2023]
Abstract
In the nineteenth century, there was a dispute about the existence of a lung alveolar epithelium which remained unsolved until the invention of electron microscopy (EM) and its application to the lung. From the early 1960s, Ewald Weibel became the master of lung EM. He showed that the alveolar epithelium is covered with a lining layer containing surfactant. Weibel also explained the phenomenon of "non-nucleated plates" observed already in 1881 by Albert Kölliker. Weibel's most significant contribution was to the development of stereological methods. Therefore, quantitative characterization of lung structure revealing structure-function relationships became possible. Today, the spectrum of EM methods to study the fine structure of the lung has been extended significantly. Cryo-preparation techniques are available which are necessary for immunogold labeling of molecules. Energy-filtering techniques can be used for the detection of elements. There have also been major improvements in stereology, thus providing a very versatile toolbox for quantitative lung phenotype analyses. A new dimension was added by 3D EM techniques. Depending on the desired sample size and resolution, the spectrum ranges from array tomography via serial block face scanning EM and focused ion beam scanning EM to electron tomography. These 3D datasets provide new insights into lung ultrastructure. Biomedical EM is an ever-developing field. Its high resolution remains unparalleled. Moreover, EM has the unique advantage of providing an "open view" into cells and tissues within their full architectural context. Therefore, EM will remain an indispensable tool for a better understanding of the lung's functional design.
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Affiliation(s)
- Matthias Ochs
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. .,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany. .,REBIRTH Cluster of Excellence, Hannover, Germany.
| | - Lars Knudsen
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany.,REBIRTH Cluster of Excellence, Hannover, Germany
| | - Jan Hegermann
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,REBIRTH Cluster of Excellence, Hannover, Germany
| | - Christoph Wrede
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,REBIRTH Cluster of Excellence, Hannover, Germany
| | - Roman Grothausmann
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,REBIRTH Cluster of Excellence, Hannover, Germany
| | - Christian Mühlfeld
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany.,REBIRTH Cluster of Excellence, Hannover, Germany
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Bildgebung von bioorthogonalen Gruppen in ihrem ultrastrukturellen Kontext mittels Elektronenmikroskopie. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201604672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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41
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Danbolt NC, Zhou Y, Furness DN, Holmseth S. Strategies for immunohistochemical protein localization using antibodies: What did we learn from neurotransmitter transporters in glial cells and neurons. Glia 2016; 64:2045-2064. [PMID: 27458697 DOI: 10.1002/glia.23027] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 06/19/2016] [Accepted: 06/21/2016] [Indexed: 12/11/2022]
Abstract
Immunocytochemistry and Western blotting are still major methods for protein localization, but they rely on the specificity of the antibodies. Validation of antibody specificity remains challenging mostly because ideal negative controls are often unavailable. Further, immunochemical labeling patterns are also influenced by a number of other factors such as postmortem changes, fixation procedures and blocking agents as well as the general assay conditions (e.g., buffers, temperature, etc.). Western blotting similarly depends on tissue collection and sample preparation as well as the electrophoretic separation, transfer to blotting membranes and the immunochemical probing of immobilized molecules. Publication of inaccurate information on protein distribution has downstream consequences for other researchers because the interpretation of physiological and pharmacological observations depends on information on where ion channels, receptors, enzymes or transporters are located. Despite numerous reports, some of which are strongly worded, erroneous localization data are being published. Here we describe the extent of the problem and illustrate the nature of the pitfalls with examples from studies of neurotransmitter transporters. We explain the importance of supplementing immunochemical observations with other measurements (e.g., mRNA levels and distribution, protein activity, mass spectrometry, electrophysiological recordings, etc.) and why quantitative considerations are integral parts of the quality control. Further, we propose a practical strategy for researchers who plan to embark on a localization study. We also share our thoughts about guidelines for quality control. GLIA 2016;64:2045-2064.
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Affiliation(s)
- Niels Christian Danbolt
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
| | - Yun Zhou
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - David N Furness
- School of Life Sciences, Keele University, Keele, Staffs, United Kingdom
| | - Silvia Holmseth
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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van Elsland DM, van Kasteren SI. Imaging Bioorthogonal Groups in Their Ultrastructural Context with Electron Microscopy. Angew Chem Int Ed Engl 2016; 55:9472-3. [PMID: 27346592 DOI: 10.1002/anie.201604672] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Indexed: 01/16/2023]
Abstract
Spitting image: Herein a recent paper on the imaging of bioorthogonal groups using three-dimensional electron microscopy is discussed. The work has demonstrated electron microscopy imaging as a technique suitable for gaining structural information on bioorthogonal groups in their cellular context.
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Affiliation(s)
- Daphne M van Elsland
- Leiden Institute of Chemistry/Institute of Chemical Immunology, Bioorganic Synthesis, Leiden University, Einsteinweg 55, 2333, CC, Leiden, The Netherlands
| | - Sander I van Kasteren
- Leiden Institute of Chemistry/Institute of Chemical Immunology, Bioorganic Synthesis, Leiden University, Einsteinweg 55, 2333, CC, Leiden, The Netherlands.
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43
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Repnik U, Hafner Česen M, Turk B. Strategies for Assaying Lysosomal Membrane Permeabilization. Cold Spring Harb Protoc 2016; 2016:2016/6/pdb.top077479. [PMID: 27250949 DOI: 10.1101/pdb.top077479] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Late endosomal organelles have an acidic pH and contain hydrolytic enzymes to degrade cargo delivered either from the extracellular environment by endocytosis or from within the cell itself by autophagy. In the event of lysosomal membrane permeabilization (LMP), the contents of late endosomes and lysosomes can be released into the cytosol and then initiate apoptosis. Compounds that can trigger LMP are therefore candidates for the induction of apoptosis, in particular in anticancer therapy. Alternatively, drug-delivery systems, such as nanoparticles, can have side effects that can include LMP, which has toxic consequences for the cells. To determine when, to what extent, and with what consequences LMP occurs is therefore of paramount importance for the evaluation of new potentially LMP-inducing compounds. In this introduction, we provide an overview of some basic assays for assessing LMP, such as staining with lysosomotropic dyes and measurement of cysteine cathepsin activity, and discuss additional strategies for the detection of the release of endogenous lysosomal molecules or preloaded exogenous tracers into the cytosol.
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Affiliation(s)
- Urška Repnik
- Department of Biochemistry and Molecular and Structural Biology, J. Stefan Institute, SI-1000 Ljubljana, Slovenia Department of Biosciences, University of Oslo, NO-0371 Oslo, Norway
| | - Maruša Hafner Česen
- Department of Biochemistry and Molecular and Structural Biology, J. Stefan Institute, SI-1000 Ljubljana, Slovenia
| | - Boris Turk
- Department of Biochemistry and Molecular and Structural Biology, J. Stefan Institute, SI-1000 Ljubljana, Slovenia Center of Excellence CIPKEBIP, SI-1000 Ljubljana, Slovenia
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44
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A simple solution for antibody signal enhancement in immunofluorescence and triple immunogold assays. Histochem Cell Biol 2016; 146:421-30. [DOI: 10.1007/s00418-016-1447-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/06/2016] [Indexed: 10/21/2022]
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van Elsland DM, Bos E, de Boer W, Overkleeft HS, Koster AJ, van Kasteren SI. Detection of bioorthogonal groups by correlative light and electron microscopy allows imaging of degraded bacteria in phagocytes. Chem Sci 2016; 7:752-758. [PMID: 28791116 PMCID: PMC5529995 DOI: 10.1039/c5sc02905h] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 10/21/2015] [Indexed: 01/07/2023] Open
Abstract
The interaction between parasites and phagocytic immune cells is a key inter-species interaction in biology. Normally, phagocytosis results in the killing of invaders, but obligate intracellular parasites hijack the pathway to ensure their survival and replication. The in situ study of these parasites in the phagocytic pathway is very difficult, as genetic modification is often complicated and, if successful, only allows the tracking of pathogen phagocytosis up until the degradation of the engineered reporter constructs. Here we combine bioorthogonal chemistry with correlative light-electron microscopy (CLEM) to follow bacterial processing in the phagolysosomal system. Labelled bacteria are produced using bioorthogonal non-canonical amino tagging (BONCAT), precluding the need for any genetic modification. The bacterial proteome - even during degradation - was then visualised using a novel CLEM-based approach. This allowed us to obtain high resolution information about the subcellular location of the degrading bacteria, even after the proteolytic degradation of reporter constructs. To further explore the potential of CLEM-based imaging of bioorthogonal functionalities, azide-labelled glycans were imaged by this same approach, as well as active-subpopulations of enzymes using a 2-step activity-based protein profiling strategy.
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Affiliation(s)
- Daphne M van Elsland
- Division of Bio-organic Synthesis , Leiden Institute of Chemistry , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands .
- Institute for Chemical Immunology , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands
| | - Erik Bos
- Department of Molecular Cell Biology , Section Electron Microscopy , Leiden University Medical Center , Leiden , The Netherlands .
| | - Wouter de Boer
- Division of Bio-organic Synthesis , Leiden Institute of Chemistry , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands .
- Institute for Chemical Immunology , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands
| | - Herman S Overkleeft
- Division of Bio-organic Synthesis , Leiden Institute of Chemistry , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands .
- Institute for Chemical Immunology , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands
| | - Abraham J Koster
- Department of Molecular Cell Biology , Section Electron Microscopy , Leiden University Medical Center , Leiden , The Netherlands .
| | - Sander I van Kasteren
- Division of Bio-organic Synthesis , Leiden Institute of Chemistry , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands .
- Institute for Chemical Immunology , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands
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Azimi I, Beilby H, Davis FM, Marcial DL, Kenny PA, Thompson EW, Roberts-Thomson SJ, Monteith GR. Altered purinergic receptor-Ca²⁺ signaling associated with hypoxia-induced epithelial-mesenchymal transition in breast cancer cells. Mol Oncol 2016; 10:166-78. [PMID: 26433470 PMCID: PMC5528926 DOI: 10.1016/j.molonc.2015.09.006] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 09/03/2015] [Accepted: 09/03/2015] [Indexed: 01/09/2023] Open
Abstract
Hypoxia is a feature of the microenvironment of many cancers and can trigger epithelial-mesenchymal transition (EMT), a process by which cells acquire a more invasive phenotype with enriched survival. A remodeling of adenosine 5'-triphosphate (ATP)-induced Ca(2+) signaling via purinergic receptors is associated with epidermal growth factor (EGF)-induced EMT in MDA-MB-468 breast cancer cells. Here, we assessed ATP-mediated Ca(2+) signaling in a model of hypoxia-induced EMT in MDA-MB-468 cells. Like EGF, hypoxia treatment (1% O2) was also associated with a significant reduction in the sensitivity of MDA-MB-468 cells to ATP (EC50 of 0.5 μM for normoxic cells versus EC50 of 5.8 μM for hypoxic cells). Assessment of mRNA levels of a panel of P2X and P2Y purinergic receptors following hypoxia revealed a change in levels of a suite of purinergic receptors. P2X4, P2X5, P2X7, P2Y1 and P2Y11 mRNAs decreased with hypoxia, whereas P2Y6 mRNA increased. Up-regulation of P2Y6 was a common feature of both growth factor- and hypoxia-induced models of EMT. P2Y6 levels were also significantly increased in basal-like breast tumors compared to other subtypes and breast cancer patients with higher P2Y6 levels showed reduced overall survival rates. P2Y6 siRNA-mediated silencing and the P2Y6 pharmacological inhibitor MRS2578 reduced hypoxia-induced vimentin protein expression in MDA-MB-468 cells. P2Y6 inhibition also reduced the migration of mesenchymal-like MDA-MB-231 breast cancer cells. The up-regulation of P2Y6 appears to be a common feature of the mesenchymal phenotype of breast cancer cells and inhibition of this receptor may represent a novel therapeutic target in breast cancer metastasis.
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Affiliation(s)
- Iman Azimi
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia; Mater Research Institute, The University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Hannah Beilby
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
| | - Felicity M Davis
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
| | - Daneth L Marcial
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
| | - Paraic A Kenny
- Kabara Cancer Research Institute, Gundersen Medical Foundation, La Crosse, WI, USA
| | - Erik W Thompson
- Institute of Health and Biomedical Innovation and School of Biomedical Sciences, Queensland University of Technology, Kelvin Grove, Queensland, Australia; University of Melbourne Department of Surgery, St Vincent's Hospital, Fitzroy, Victoria, Australia; St Vincent's Institute, Fitzroy, Victoria, Australia
| | | | - Gregory R Monteith
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia; Mater Research Institute, The University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia.
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Langbein L, Eckhart L, Fischer H, Rogers MA, Praetzel-Wunder S, Parry DAD, Kittstein W, Schweizer J. Localisation of keratin K78 in the basal layer and first suprabasal layers of stratified epithelia completes expression catalogue of type II keratins and provides new insights into sequential keratin expression. Cell Tissue Res 2015; 363:735-50. [PMID: 26340985 DOI: 10.1007/s00441-015-2278-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 08/07/2015] [Indexed: 01/21/2023]
Abstract
Among the 26 human type II keratins, K78 is the only one that has not yet been explored with regard to its expression characteristics. Here, we show that, at both the transcriptional and translational levels, K78 is strongly expressed in the basal and parabasal cell layers with decreasing intensity in the lower suprabasal cells of keratinising and non-keratinising squamous epithelia and keratinocyte cultures. The same pattern has been detected at the transcriptional level in the corresponding mouse epithelia. Murine K78 protein, which contains an extraordinary large extension of its tail domain, which is unique among all known keratins, is not detectable by the antibody used. Concomitant studies in human epithelia have confirmed K78 co-expression with the classical basal keratins K5 and K14. Similarly, K78 co-expression with the differentiation-related type I keratins K10 (epidermis) and K13 (non-keratinising epithelia) occurs in the parabasal cell layer, whereas that of the corresponding type II keratins K1 (epidermis) and K4 (non-keratinising epithelia) unequivocally starts subsequent to the respective type I keratins. Our data concerning K78 expression modify the classical concept of keratin pair K5/K14 representing the basal compartment and keratin pairs K1/K10 or K4/K13 defining the differentiating compartment of stratified epithelia. Moreover, the K78 expression pattern and the decoupled K1/K10 and K4/K13 expression define the existence of a hitherto unperceived early differentiation stage in the parabasal layer characterized by K78/K10 or K78/K13 expression.
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MESH Headings
- Adult
- Amino Acid Sequence
- Animals
- Carcinoma, Squamous Cell/metabolism
- Carcinoma, Squamous Cell/pathology
- Embryonic Development
- Epidermis/metabolism
- Epithelium/metabolism
- Evolution, Molecular
- Fluorescent Antibody Technique
- Gene Expression Regulation
- Genetic Loci
- Humans
- In Situ Hybridization
- Keratinocytes/metabolism
- Keratins, Type II/chemistry
- Keratins, Type II/genetics
- Keratins, Type II/metabolism
- Mice, Inbred C57BL
- Molecular Sequence Data
- Protein Transport
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Sequence Analysis, Protein
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Affiliation(s)
- Lutz Langbein
- Department of Genetics of Skin Carcinogenesis, German Cancer Research Center, A110, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.
| | - Leopold Eckhart
- Department of Dermatology, Medical University Vienna, Vienna, Austria
| | - Heinz Fischer
- Department of Dermatology, Medical University Vienna, Vienna, Austria
| | - Michael A Rogers
- Department of Molecular Genetics of the German Cancer Research Center, Heidelberg, Germany
| | - Silke Praetzel-Wunder
- Department of Genetics of Skin Carcinogenesis, German Cancer Research Center, A110, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - David A D Parry
- Institute of Fundamental Sciences and Riddet Institute, Massey University, Palmerston North, New Zealand
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48
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The potential of bioorthogonal chemistry for correlative light and electron microscopy: a call to arms. J Chem Biol 2015. [DOI: 10.1007/s12154-015-0134-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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49
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Nicolle O, Burel A, Griffiths G, Michaux G, Kolotuev I. Adaptation of Cryo-Sectioning for IEM Labeling of Asymmetric Samples: A Study Using Caenorhabditis elegans. Traffic 2015; 16:893-905. [PMID: 25858477 DOI: 10.1111/tra.12289] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 04/07/2015] [Accepted: 04/08/2015] [Indexed: 01/17/2023]
Abstract
Cryo-sectioning procedures, initially developed by Tokuyasu, have been successfully improved for tissues and cultured cells, enabling efficient protein localization on the ultrastructural level. Without a standard procedure applicable to any sample, currently existing protocols must be individually modified for each model organism or asymmetric sample. Here, we describe our method that enables reproducible cryo-sectioning of Caenorhabditis elegans larvae/adults and embryos. We have established a chemical-fixation procedure in which flat embedding considerably simplifies manipulation and lateral orientation of larvae or adults. To bypass the limitations of chemical fixation, we have improved the hybrid cryo-immobilization-rehydration technique and reduced the overall time required to complete this procedure. Using our procedures, precise cryo-sectioning orientation can be combined with good ultrastructural preservation and efficient immuno-electron microscopy protein localization. Also, GFP fluorescence can be efficiently preserved, permitting a direct correlation of the fluorescent signal and its subcellular localization. Although developed for C. elegans samples, our method addresses the challenge of working with small asymmetric samples in general, and thus could be used to improve the efficiency of immuno-electron localization in other model organisms.
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Affiliation(s)
- Ophélie Nicolle
- Institut de Génétique et Développement de Rennes, Faculté de Médecine, CNRS, Université de Rennes 1, F-35043, Rennes, France
| | - Agnès Burel
- Plateforme microscopie électronique MRic, Université de Rennes 1, UEB, SFR Biosit, UMS 'BIOSIT' CNRS 3480-INSERM 018, F-35043, Rennes, France
| | - Gareth Griffiths
- Department of Biosciences, University of Oslo, Blindernveien 31, 0371 Oslo, Norway
| | - Grégoire Michaux
- Institut de Génétique et Développement de Rennes, Faculté de Médecine, CNRS, Université de Rennes 1, F-35043, Rennes, France.,Plateforme microscopie électronique MRic, Université de Rennes 1, UEB, SFR Biosit, UMS 'BIOSIT' CNRS 3480-INSERM 018, F-35043, Rennes, France
| | - Irina Kolotuev
- Institut de Génétique et Développement de Rennes, Faculté de Médecine, CNRS, Université de Rennes 1, F-35043, Rennes, France.,Plateforme microscopie électronique MRic, Université de Rennes 1, UEB, SFR Biosit, UMS 'BIOSIT' CNRS 3480-INSERM 018, F-35043, Rennes, France
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50
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Mayhew T. Morphomics: An integral part of systems biology of the human placenta. Placenta 2015; 36:329-40. [DOI: 10.1016/j.placenta.2015.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 01/05/2015] [Accepted: 01/07/2015] [Indexed: 01/03/2023]
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