1
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Wenzel EM, Pedersen NM, Elfmark LA, Wang L, Kjos I, Stang E, Malerød L, Brech A, Stenmark H, Raiborg C. Intercellular transfer of cancer cell invasiveness via endosome-mediated protease shedding. Nat Commun 2024; 15:1277. [PMID: 38341434 PMCID: PMC10858897 DOI: 10.1038/s41467-024-45558-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 01/26/2024] [Indexed: 02/12/2024] Open
Abstract
Overexpression of the transmembrane matrix metalloproteinase MT1-MMP/MMP14 promotes cancer cell invasion. Here we show that MT1-MMP-positive cancer cells turn MT1-MMP-negative cells invasive by transferring a soluble catalytic ectodomain of MT1-MMP. Surprisingly, this effect depends on the presence of TKS4 and TKS5 in the donor cell, adaptor proteins previously implicated in invadopodia formation. In endosomes of the donor cell, TKS4/5 promote ADAM-mediated cleavage of MT1-MMP by bridging the two proteases, and cleavage is stimulated by the low intraluminal pH of endosomes. The bridging depends on the PX domains of TKS4/5, which coincidently interact with the cytosolic tail of MT1-MMP and endosomal phosphatidylinositol 3-phosphate. MT1-MMP recruits TKS4/5 into multivesicular endosomes for their subsequent co-secretion in extracellular vesicles, together with the enzymatically active ectodomain. The shed ectodomain converts non-invasive recipient cells into an invasive phenotype. Thus, TKS4/5 promote intercellular transfer of cancer cell invasiveness by facilitating ADAM-mediated shedding of MT1-MMP in acidic endosomes.
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Affiliation(s)
- Eva Maria Wenzel
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Nina Marie Pedersen
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Liv Anker Elfmark
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Ling Wang
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Ingrid Kjos
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Espen Stang
- Laboratory for Molecular and Cellular Cancer Research, Department of Pathology, Oslo University Hospital, Oslo, Norway
| | - Lene Malerød
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Andreas Brech
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Section for Physiology and Cell Biology, Dept. of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
| | - Harald Stenmark
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Camilla Raiborg
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway.
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
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2
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Hacker C, Sendra K, Keisham P, Filipescu T, Lucocq J, Salimi F, Ferguson S, Bhella D, MacNeill SA, Embley M, Lucocq J. Biogenesis, inheritance, and 3D ultrastructure of the microsporidian mitosome. Life Sci Alliance 2024; 7:e202201635. [PMID: 37903625 PMCID: PMC10618108 DOI: 10.26508/lsa.202201635] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/02/2023] [Accepted: 10/03/2023] [Indexed: 11/01/2023] Open
Abstract
During the reductive evolution of obligate intracellular parasites called microsporidia, a tiny remnant mitochondrion (mitosome) lost its typical cristae, organellar genome, and most canonical functions. Here, we combine electron tomography, stereology, immunofluorescence microscopy, and bioinformatics to characterise mechanisms of growth, division, and inheritance of this minimal mitochondrion in two microsporidia species (grown within a mammalian RK13 culture-cell host). Mitosomes of Encephalitozoon cuniculi (2-12/cell) and Trachipleistophora hominis (14-18/nucleus) displayed incremental/non-phasic growth and division and were closely associated with an organelle identified as equivalent to the fungal microtubule-organising centre (microsporidian spindle pole body; mSPB). The mitosome-mSPB association was resistant to treatment with microtubule-depolymerising drugs nocodazole and albendazole. Dynamin inhibitors (dynasore and Mdivi-1) arrested mitosome division but not growth, whereas bioinformatics revealed putative dynamins Drp-1 and Vps-1, of which, Vps-1 rescued mitochondrial constriction in dynamin-deficient yeast (Schizosaccharomyces pombe). Thus, microsporidian mitosomes undergo incremental growth and dynamin-mediated division and are maintained through ordered inheritance, likely mediated via binding to the microsporidian centrosome (mSPB).
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Affiliation(s)
- Christian Hacker
- https://ror.org/02wn5qz54 School of Medicine, University of St Andrews, St Andrews, UK
| | - Kacper Sendra
- Biosciences Institute, The Medical School, Catherine Cookson Building, Newcastle University, Newcastle upon Tyne, UK
| | - Priyanka Keisham
- https://ror.org/02wn5qz54 School of Medicine, University of St Andrews, St Andrews, UK
| | - Teodora Filipescu
- https://ror.org/02wn5qz54 School of Medicine, University of St Andrews, St Andrews, UK
| | - James Lucocq
- Department of Surgery, Dundee Medical School Ninewells Hospital, Dundee, UK
| | - Fatemeh Salimi
- https://ror.org/02wn5qz54 School of Medicine, University of St Andrews, St Andrews, UK
| | - Sophie Ferguson
- https://ror.org/02wn5qz54 School of Medicine, University of St Andrews, St Andrews, UK
| | - David Bhella
- MRC-University of Glasgow Centre for Virus Research, Glasgow, UK
| | - Stuart A MacNeill
- https://ror.org/02wn5qz54 School of Biology, University of St Andrews, St Andrews, UK
| | - Martin Embley
- Biosciences Institute, Centre for Bacterial Cell Biology, Baddiley-Clark Building, Newcastle University, Newcastle upon Tyne, UK
| | - John Lucocq
- https://ror.org/02wn5qz54 School of Medicine, University of St Andrews, St Andrews, UK
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3
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D'Ambra E, Vitiello E, Santini T, Bozzoni I. In Situ Hybridization of circRNAs in Cells and Tissues through BaseScope™ Strategy. Methods Mol Biol 2024; 2765:63-92. [PMID: 38381334 DOI: 10.1007/978-1-0716-3678-7_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Imaging-based approaches are powerful strategies that nowadays have been largely used to gain insight into the function of different types of macromolecules. As for RNA, it is becoming clear how important is its intracellular localization for the control of proper cell differentiation and development and how its perturbation can be linked to several pathological states. This aspect is even more important if one thinks of highly polarized cells such as neurons.In this chapter, we describe in detail an innovative RNA-FISH approach for the detection of circular RNAs (circRNAs), a recently discovered class of noncoding RNAs, which display different subcellular localizations and whose functions still largely remain to be elucidated. The detection of these molecules represents a great challenge, above all because they share most of their sequence with the corresponding linear counterparts, from which they differ only for the back-splicing junction (BSJ) originating from the circularization reaction. This implies the use of RNA-FISH probes capable of specifically binding the BSJ and avoiding the detection of the linear counterpart. This requirement imposes the design of probes on a very small region, which implies the risk of obtaining a low and undetectable signal. The BaseScope™ Assay RNA-FISH technology overpasses this problem since it is based on branched-DNA probes. With this approach it is possible to target a specific region of the RNA, even small such as a splicing junction, and at the same time to obtain a strong and well detectable signal. All this is possible thanks to subsequent series of probes that, starting from the first hybridization to the BSJ, build a branched tree of probes that greatly amplifies the signal. Here we provide a detailed step-by-step protocol of BaseScope™ RNA-FISH on circRNAs coupled with immunofluorescence, both in cells and tissues, and we address difficulties which may arise when using this methodology that depend on cell type, specific permeabilization, image acquisition, and post-acquisition analyses.
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Affiliation(s)
- Eleonora D'Ambra
- Center for Life Nano- & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), Rome, Italy
| | - Erika Vitiello
- Center for Human Technology, Istituto Italiano di Tecnologia (IIT), Genoa, Italy
- Department of Biology and Biotechnologies "Charles Darwin", Sapienza University of Rome, Rome, Italy
| | - Tiziana Santini
- Department of Biology and Biotechnologies "Charles Darwin", Sapienza University of Rome, Rome, Italy
| | - Irene Bozzoni
- Center for Life Nano- & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), Rome, Italy.
- Center for Human Technology, Istituto Italiano di Tecnologia (IIT), Genoa, Italy.
- Department of Biology and Biotechnologies "Charles Darwin", Sapienza University of Rome, Rome, Italy.
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4
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Hessvik NP, Sagini K, Romero S, Ramirez-Garrastacho M, Rodriguez M, Tutturen AEV, Kvalvaag A, Stang E, Brech A, Sandvig K, Llorente A. siRNA screening reveals that SNAP29 contributes to exosome release. Cell Mol Life Sci 2023; 80:177. [PMID: 37285022 DOI: 10.1007/s00018-023-04822-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 05/22/2023] [Accepted: 05/23/2023] [Indexed: 06/08/2023]
Abstract
Cells release extracellular vesicles (EVs) of different sizes. Small EVs (< 200 nm) can originate from the fusion of multivesicular bodies with the plasma membrane, i.e. exosomes, and from budding of the plasma membrane, i.e. small ectosomes. To investigate the molecular machinery required for the release of small EVs, we developed a sensitive assay based on incorporation of radioactive cholesterol in EV membranes and used it in a siRNA screening. The screening showed that depletion of several SNARE proteins affected the release of small EVs. We focused on SNAP29, VAMP8, syntaxin 2, syntaxin 3 and syntaxin 18, the depletion of which reduced the release of small EVs. Importantly, this result was verified using gold standard techniques. SNAP29 depletion resulted in the largest effect and was further investigated. Immunoblotting analysis of small EVs showed that the release of several proteins considered to be associated with exosomes like syntenin, CD63 and Tsg101 was reduced, while the level of several proteins that have been shown to be released in ectosomes (annexins) or by secretory autophagy (LC3B and p62) was not affected by SNAP29 depletion. Moreover, these proteins appeared in different fractions when the EV samples were further separated by a density gradient. These results suggest that SNAP29 depletion mainly affects the secretion of exosomes. To investigate how SNAP29 affects exosome release, we used microscopy to study the distribution of MBVs using CD63 labelling and CD63-pHluorin to detect fusion events of MVBs with the plasma membrane. SNAP29 depletion caused a redistribution of CD63-labelled compartments but did not change the number of fusion events. Further experiments are therefore needed to fully understand the function of SNAP29. To conclude, we have developed a novel screening assay that has allowed us to identify several SNAREs involved in the release of small EVs.
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Affiliation(s)
- Nina Pettersen Hessvik
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Krizia Sagini
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Silvana Romero
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Manuel Ramirez-Garrastacho
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Marta Rodriguez
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Pathology Department, IIS-Fundación Jiménez Díaz-UAM, Center for the Biomedical Research Network in Oncology, CIBERONC, Madrid, Spain
| | | | - Audun Kvalvaag
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Espen Stang
- Department of Pathology, Oslo University Hospital, Oslo, Norway
| | - Andreas Brech
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Kirsten Sandvig
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - Alicia Llorente
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway.
- Department for Mechanical, Electronics and Chemical Engineering, Oslo Metropolitan University, Oslo, Norway.
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5
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Bhandari M, Soria-Carrera H, Wohlmann J, Dal NJK, de la Fuente JM, Martín-Rapún R, Griffiths G, Fenaroli F. Subcellular localization and therapeutic efficacy of polymeric micellar nanoparticles encapsulating bedaquiline for tuberculosis treatment in zebrafish. Biomater Sci 2023; 11:2103-2114. [PMID: 36723226 DOI: 10.1039/d2bm01835g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The combination drug regimens that have long been used to treat tuberculosis (TB), caused by Mycobacterium tuberculosis, are fraught with problems such as frequent administration, long duration of treatment, and harsh adverse effects, leading to the emergence of multidrug resistance. Moreover, there is no effective preventive vaccine against TB infection. In this context, nanoparticles (NPs) have emerged as a potential alternative method for drug delivery. Encapsulating antibiotics in biodegradable NPs has been shown to provide effective therapy and reduced toxicity against M. tuberculosis in different mammalian models, when compared to conventional free drug administration. Here, we evaluate the localization, therapeutic efficacy and toxic effects of polymeric micellar NPs encapsulating a promising but highly hydrophobic and toxic antitubercular drug bedaquiline (BQ) in zebrafish embryos infected with Mycobacterium marinum. Our study shows that the NP formulation of BQ improves survival and reduces bacterial burden in the infected embryos after treatment when compared to its free form. The intravenously injected BQ NPs have short circulation times due to their rapid and efficient uptake into the endothelial cells, as observed by correlative light and electron microscopy (CLEM).
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Affiliation(s)
- Madhavi Bhandari
- Department of Biosciences, University of Oslo, Blindernveien 31, 0371 Oslo, Norway
| | - Héctor Soria-Carrera
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, C/Mariano Esquillor s/n, 50018 Zaragoza, Spain. .,CIBER de Bioingeniería, Biomateriales y Nanomedicina, Instituto de Salud Carlos III, 28029 Madrid, Spain.,Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Zaragoza, c/Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Jens Wohlmann
- Department of Biosciences, University of Oslo, Blindernveien 31, 0371 Oslo, Norway
| | | | - Jesús M de la Fuente
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, C/Mariano Esquillor s/n, 50018 Zaragoza, Spain. .,CIBER de Bioingeniería, Biomateriales y Nanomedicina, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Rafael Martín-Rapún
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, C/Mariano Esquillor s/n, 50018 Zaragoza, Spain. .,CIBER de Bioingeniería, Biomateriales y Nanomedicina, Instituto de Salud Carlos III, 28029 Madrid, Spain.,Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Zaragoza, c/Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Gareth Griffiths
- Department of Biosciences, University of Oslo, Blindernveien 31, 0371 Oslo, Norway
| | - Federico Fenaroli
- Department of Biosciences, University of Oslo, Blindernveien 31, 0371 Oslo, Norway.,Department of Chemistry, Bioscience and Environmental Engineering, University of Stavanger, 4021 Stavanger, Norway.
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6
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Characterization and Vaccine Potential of Outer Membrane Vesicles from Photobacterium damselae subsp. piscicida. Int J Mol Sci 2023; 24:ijms24065138. [PMID: 36982212 PMCID: PMC10049053 DOI: 10.3390/ijms24065138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/01/2023] [Accepted: 03/03/2023] [Indexed: 03/11/2023] Open
Abstract
Photobacterium damselae subsp. piscicida (Phdp) is a Gram-negative fish pathogen with worldwide distribution and broad host specificity that causes heavy economic losses in aquaculture. Although Phdp was first identified more than 50 years ago, its pathogenicity mechanisms are not completely understood. In this work, we report that Phdp secretes large amounts of outer membrane vesicles (OMVs) when cultured in vitro and during in vivo infection. These OMVs were morphologically characterized and the most abundant vesicle-associated proteins were identified. We also demonstrate that Phdp OMVs protect Phdp cells from the bactericidal activity of fish antimicrobial peptides, suggesting that secretion of OMVs is part of the strategy used by Phdp to evade host defense mechanisms. Importantly, the vaccination of sea bass (Dicentrarchus labrax) with adjuvant-free crude OMVs induced the production of anti-Phdp antibodies and resulted in partial protection against Phdp infection. These findings reveal new aspects of Phdp biology and may provide a basis for developing new vaccines against this pathogen.
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7
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Mandel M, Holtmann L, Raiwa M, Wunnenberg-Gust A, Riebe B, Walther C. Imaging of I, Re and Tc plant uptake on the single-cell scale using SIMS and rL-SNMS. JOURNAL OF HAZARDOUS MATERIALS 2022; 423:127143. [PMID: 34517301 DOI: 10.1016/j.jhazmat.2021.127143] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 08/27/2021] [Accepted: 09/02/2021] [Indexed: 06/13/2023]
Abstract
In radioecological studies, there is a significant need for understanding the plant uptake of radionuclides on a cellular level. The present work applies mass spectrometry to image the radionuclide distribution within the cellular structures of plants at varying concentrations. In a first step, plants of Daucus carota and Pisum sativum labelled with iodine and rhenium were examined, at concentrations in the range of 10 mM. Cross sections of several plant parts were imaged by secondary ion mass spectrometry (SIMS) after cryogenation in order to preserve cell structure. In a second step, the distribution of 99Tc in the two plant species was determined. For radiological reasons, a concentration three orders of magnitude lower was used, rendering measurements with SIMS impossible. Therefore, resonant laser secondary neutral mass spectrometry (rL-SNMS) was used for the first time to image 99Tc with suppression of molecular isobaric interferences. The measurement of only about 1010 atoms of 99Tc atoms is demonstrated and the distribution of 99Tc within a single epidermal cell is imaged.
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Affiliation(s)
- Marcus Mandel
- Institute of Radioecology and Radiation Protection, Leibniz Universität Hannover, D-30419 Hannover, Germany
| | - Linus Holtmann
- Institute of Radioecology and Radiation Protection, Leibniz Universität Hannover, D-30419 Hannover, Germany
| | - Manuel Raiwa
- Institute of Radioecology and Radiation Protection, Leibniz Universität Hannover, D-30419 Hannover, Germany
| | - Annika Wunnenberg-Gust
- Institute of Radioecology and Radiation Protection, Leibniz Universität Hannover, D-30419 Hannover, Germany
| | - Beate Riebe
- Institute of Radioecology and Radiation Protection, Leibniz Universität Hannover, D-30419 Hannover, Germany
| | - Clemens Walther
- Institute of Radioecology and Radiation Protection, Leibniz Universität Hannover, D-30419 Hannover, Germany.
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8
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Sousa AL, Rodrigues Lóios J, Faísca P, Tranfield EM. The Histo-CLEM Workflow for tissues of model organisms. Methods Cell Biol 2021; 162:13-37. [PMID: 33707010 DOI: 10.1016/bs.mcb.2020.12.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Bridging from the macrostructure to the nanostructure of tissues is often technically challenging. To try to solve this, we developed a flexible CLEM workflow that can be applied to the analysis of tissues from diverse model organisms across various length scales. The Histo-CLEM Workflow combines three main microscopy techniques, namely histology, light microscopy and electron microscopy. Herein, all the steps of the Histo-CLEM Workflow are explained in detail to enable the adaptation of the method to tissue particularities and biological questions. The preparation and visualization of mice nerve fibers is shown as an application example of the presented Histo-CLEM Workflow.
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Affiliation(s)
- Ana Laura Sousa
- Electron Microscopy Facility-Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | | | - Pedro Faísca
- Histopathology Facility-Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Erin M Tranfield
- Electron Microscopy Facility-Instituto Gulbenkian de Ciência, Oeiras, Portugal.
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9
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Vijayakrishnan S, McElwee M, Loney C, Rixon F, Bhella D. In situ structure of virus capsids within cell nuclei by correlative light and cryo-electron tomography. Sci Rep 2020; 10:17596. [PMID: 33077791 PMCID: PMC7572381 DOI: 10.1038/s41598-020-74104-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 09/24/2020] [Indexed: 12/02/2022] Open
Abstract
Cryo electron microscopy (cryo-EM), a key method for structure determination involves imaging purified material embedded in vitreous ice. Images are then computationally processed to obtain three-dimensional structures approaching atomic resolution. There is increasing interest in extending structural studies by cryo-EM into the cell, where biological structures and processes may be imaged in context. The limited penetrating power of electrons prevents imaging of thick specimens (> 500 nm) however. Cryo-sectioning methods employed to overcome this are technically challenging, subject to artefacts or involve specialised and costly equipment. Here we describe the first structure of herpesvirus capsids determined by sub-tomogram averaging from nuclei of eukaryotic cells, achieved by cryo-electron tomography (cryo-ET) of re-vitrified cell sections prepared using the Tokuyasu method. Our reconstructions confirm that the capsid associated tegument complex is present on capsids prior to nuclear egress. We demonstrate that this method is suited to both 3D structure determination and correlative light/electron microscopy, thus expanding the scope of cryogenic cellular imaging.
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Affiliation(s)
- Swetha Vijayakrishnan
- MRC-University of Glasgow Centre for Virus Research, Sir Michael Stoker Building, Garscube Campus, 464 Bearsden Road, Glasgow, G61 1QH, Scotland, UK.
| | - Marion McElwee
- MRC-University of Glasgow Centre for Virus Research, Sir Michael Stoker Building, Garscube Campus, 464 Bearsden Road, Glasgow, G61 1QH, Scotland, UK
| | - Colin Loney
- MRC-University of Glasgow Centre for Virus Research, Sir Michael Stoker Building, Garscube Campus, 464 Bearsden Road, Glasgow, G61 1QH, Scotland, UK
| | - Frazer Rixon
- MRC-University of Glasgow Centre for Virus Research, Sir Michael Stoker Building, Garscube Campus, 464 Bearsden Road, Glasgow, G61 1QH, Scotland, UK
| | - David Bhella
- MRC-University of Glasgow Centre for Virus Research, Sir Michael Stoker Building, Garscube Campus, 464 Bearsden Road, Glasgow, G61 1QH, Scotland, UK
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10
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Spatial mapping of the collagen distribution in human and mouse tissues by force volume atomic force microscopy. Sci Rep 2020; 10:15664. [PMID: 32973235 PMCID: PMC7518416 DOI: 10.1038/s41598-020-72564-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 08/20/2020] [Indexed: 01/06/2023] Open
Abstract
Changes in the elastic properties of living tissues during normal development and in pathological processes are often due to modifications of the collagen component of the extracellular matrix at various length scales. Force volume AFM can precisely capture the mechanical properties of biological samples with force sensitivity and spatial resolution. The integration of AFM data with data of the molecular composition contributes to understanding the interplay between tissue biochemistry, organization and function. The detection of micrometer-size, heterogeneous domains at different elastic moduli in tissue sections by AFM has remained elusive so far, due to the lack of correlations with histological, optical and biochemical assessments. In this work, force volume AFM is used to identify collagen-enriched domains, naturally present in human and mouse tissues, by their elastic modulus. Collagen identification is obtained in a robust way and affordable timescales, through an optimal design of the sample preparation method and AFM parameters for faster scan with micrometer resolution. The choice of a separate reference sample stained for collagen allows correlating elastic modulus with collagen amount and position with high statistical significance. The proposed preparation method ensures safe handling of the tissue sections guarantees the preservation of their micromechanical characteristics over time and makes it much easier to perform correlation experiments with different biomarkers independently.
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11
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Giesecke Y, Soete S, MacKinnon K, Tsiaras T, Ward M, Althobaiti M, Suveges T, Lucocq JE, McKenna SJ, Lucocq JM. Developing Electron Microscopy Tools for Profiling Plasma Lipoproteins Using Methyl Cellulose Embedment, Machine Learning and Immunodetection of Apolipoprotein B and Apolipoprotein(a). Int J Mol Sci 2020; 21:ijms21176373. [PMID: 32887372 PMCID: PMC7503711 DOI: 10.3390/ijms21176373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/26/2020] [Accepted: 08/06/2020] [Indexed: 01/17/2023] Open
Abstract
Plasma lipoproteins are important carriers of cholesterol and have been linked strongly to cardiovascular disease (CVD). Our study aimed to achieve fine-grained measurements of lipoprotein subpopulations such as low-density lipoprotein (LDL), lipoprotein(a) (Lp(a), or remnant lipoproteins (RLP) using electron microscopy combined with machine learning tools from microliter samples of human plasma. In the reported method, lipoproteins were absorbed onto electron microscopy (EM) support films from diluted plasma and embedded in thin films of methyl cellulose (MC) containing mixed metal stains, providing intense edge contrast. The results show that LPs have a continuous frequency distribution of sizes, extending from LDL (> 15 nm) to intermediate density lipoprotein (IDL) and very low-density lipoproteins (VLDL). Furthermore, mixed metal staining produces striking “positive” contrast of specific antibodies attached to lipoproteins providing quantitative data on apolipoprotein(a)-positive Lp(a) or apolipoprotein B (ApoB)-positive particles. To enable automatic particle characterization, we also demonstrated efficient segmentation of lipoprotein particles using deep learning software characterized by a Mask Region-based Convolutional Neural Networks (R-CNN) architecture with transfer learning. In future, EM and machine learning could be combined with microarray deposition and automated imaging for higher throughput quantitation of lipoproteins associated with CVD risk.
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Affiliation(s)
- Yvonne Giesecke
- Structural Cell Biology Group, School of Medicine, University of St Andrews, North Haugh, St Andrews KY16 9TF, UK; (Y.G.); (S.S.); (M.W.); (M.A.)
| | - Samuel Soete
- Structural Cell Biology Group, School of Medicine, University of St Andrews, North Haugh, St Andrews KY16 9TF, UK; (Y.G.); (S.S.); (M.W.); (M.A.)
| | - Katarzyna MacKinnon
- CVIP, School of Science and Engineering, University of Dundee, Dundee DD1 4HN, UK; (K.M.); (T.T.); (T.S.); (S.J.M.)
| | - Thanasis Tsiaras
- CVIP, School of Science and Engineering, University of Dundee, Dundee DD1 4HN, UK; (K.M.); (T.T.); (T.S.); (S.J.M.)
| | - Madeline Ward
- Structural Cell Biology Group, School of Medicine, University of St Andrews, North Haugh, St Andrews KY16 9TF, UK; (Y.G.); (S.S.); (M.W.); (M.A.)
| | - Mohammed Althobaiti
- Structural Cell Biology Group, School of Medicine, University of St Andrews, North Haugh, St Andrews KY16 9TF, UK; (Y.G.); (S.S.); (M.W.); (M.A.)
| | - Tamas Suveges
- CVIP, School of Science and Engineering, University of Dundee, Dundee DD1 4HN, UK; (K.M.); (T.T.); (T.S.); (S.J.M.)
| | - James E. Lucocq
- Department of Orthopaedics, Ninewells Hospital, James Arrott Drive, Dundee DD1 9SY, UK;
| | - Stephen J. McKenna
- CVIP, School of Science and Engineering, University of Dundee, Dundee DD1 4HN, UK; (K.M.); (T.T.); (T.S.); (S.J.M.)
| | - John M. Lucocq
- Structural Cell Biology Group, School of Medicine, University of St Andrews, North Haugh, St Andrews KY16 9TF, UK; (Y.G.); (S.S.); (M.W.); (M.A.)
- Correspondence:
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12
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Potts EM, Coppotelli G, Ross JM. Histological-Based Stainings using Free-Floating Tissue Sections. J Vis Exp 2020:10.3791/61622. [PMID: 32925894 PMCID: PMC7743918 DOI: 10.3791/61622] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Immunohistochemistry is a widely used technique to visualize specific tissue structures as well as protein expression and localization. Two alternative approaches are widely used to handle the tissue sections during the staining procedure, one approach consists of mounting the sections directly on glass slides, while a second approach, the free-floating, allows for fixed sections to be maintained and stained while suspended in solution. Although slide-mounted and free-floating approaches may yield similar results, the free-floating technique allows for better antibody penetration and thus should be the method of choice when thicker sections are to be used for 3D reconstruction of the tissues, for example when the focus of the experiment is to gain information on dendritic and axonal projections in brain regions. In addition, since the sections are kept in solution, a single aliquot can easily accommodate 30 to 40 sections, handling of which is less laborious, particularly in large-scale biomedical studies. Here, we illustrate how to apply the free-floating method to fluorescent immunohistochemistry staining, with a major focus on brain sections. We will also discuss how the free-floating technique can easily be modified to fit the individual needs of researchers and adapted to other tissues as well as other histochemical-based stainings, such as hematoxylin and eosin and cresyl violet, as long as tissue samples are properly fixed, typically with paraformaldehyde or formalin.
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Affiliation(s)
- Emily M Potts
- George & Anne Ryan Institute for Neuroscience, College of Pharmacy, Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island
| | - Giuseppe Coppotelli
- George & Anne Ryan Institute for Neuroscience, College of Pharmacy, Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island
| | - Jaime M Ross
- George & Anne Ryan Institute for Neuroscience, College of Pharmacy, Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island; Department of Neuroscience, Biomedicum, Karolinska Institutet;
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13
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Prasad S, Potdar V, Cherian S, Abraham P, Basu A. Transmission electron microscopy imaging of SARS-CoV-2. Indian J Med Res 2020; 151:241-243. [PMID: 32362648 PMCID: PMC7224615 DOI: 10.4103/ijmr.ijmr_577_20] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Sharda Prasad
- Electron Microscopy & Pathology Group, ICMR-National Institute of Virology, Pune 411 001, Maharashtra, India
| | - Varsha Potdar
- ICMR-NIV National Influenza Center & Influenza Group, ICMR-National Institute of Virology, Pune 411 001, Maharashtra, India
| | - Sarah Cherian
- Bioinformatics & Data Management Group, ICMR-National Institute of Virology, Pune 411 001, Maharashtra, India
| | - Priya Abraham
- ICMR-National Institute of Virology, Pune 411 001, Maharashtra, India
| | - Atanu Basu
- Electron Microscopy and Histopoathology Group, ICMR-National Institute of Virology, Pune 411 001, Maharashtra, India
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14
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Flechsler J, Heimerl T, Pickl C, Rachel R, Stierhof YD, Klingl A. 2D and 3D immunogold localization on (epoxy) ultrathin sections with and without osmium tetroxide. Microsc Res Tech 2020; 83:691-705. [PMID: 32057162 DOI: 10.1002/jemt.23459] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/13/2020] [Accepted: 02/04/2020] [Indexed: 11/07/2022]
Abstract
For nearly 50 years immunogold labeling on ultrathin sections has been successfully used for protein localization in laboratories worldwide. In theory and in practice, this method has undergone continual improvement over time. In this study, we carefully analyzed circulating protocols for postembedding labeling to find out if they are still valid under modern laboratory conditions, and in addition, we tested unconventional protocols. For this, we investigated immunolabeling of Epon-embedded cells, immunolabeling of cells treated with osmium, and the binding behavior of differently sized gold particles. Here we show that (in contrast to widespread belief) immunolabeling of Epon-embedded cells and of cells treated with osmium tetroxide is actually working. Furthermore, we established a "speed protocol" for immunolabeling by reducing antibody incubation times. Finally, we present our results on three-dimensional immunogold labeling.
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Affiliation(s)
- Jennifer Flechsler
- Plant Development and Electron Microscopy, Department of Biology I, Munchen, Germany
| | - Thomas Heimerl
- LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Marburg, Germany
| | - Carolin Pickl
- Plant Development and Electron Microscopy, Department of Biology I, Munchen, Germany
| | - Reinhard Rachel
- Institute of Microbiology and Centre for Electron Microscopy, University of Regensburg, Regensburg, Germany
| | - York-Dieter Stierhof
- Microscopy, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Andreas Klingl
- Plant Development and Electron Microscopy, Department of Biology I, Munchen, Germany
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15
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Moreau D, Vacca F, Vossio S, Scott C, Colaco A, Paz Montoya J, Ferguson C, Damme M, Moniatte M, Parton RG, Platt FM, Gruenberg J. Drug-induced increase in lysobisphosphatidic acid reduces the cholesterol overload in Niemann-Pick type C cells and mice. EMBO Rep 2019; 20:e47055. [PMID: 31267706 PMCID: PMC6607015 DOI: 10.15252/embr.201847055] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 04/12/2019] [Accepted: 04/23/2019] [Indexed: 12/26/2022] Open
Abstract
Most cells acquire cholesterol by endocytosis of circulating low-density lipoproteins (LDLs). After cholesteryl ester de-esterification in endosomes, free cholesterol is redistributed to intracellular membranes via unclear mechanisms. Our previous work suggested that the unconventional phospholipid lysobisphosphatidic acid (LBPA) may play a role in modulating the cholesterol flux through endosomes. In this study, we used the Prestwick library of FDA-approved compounds in a high-content, image-based screen of the endosomal lipids, lysobisphosphatidic acid and LDL-derived cholesterol. We report that thioperamide maleate, an inverse agonist of the histamine H3 receptor HRH3, increases highly selectively the levels of lysobisphosphatidic acid, without affecting any endosomal protein or function that we tested. Our data also show that thioperamide significantly reduces the endosome cholesterol overload in fibroblasts from patients with the cholesterol storage disorder Niemann-Pick type C (NPC), as well as in liver of Npc1-/- mice. We conclude that LBPA controls endosomal cholesterol mobilization and export to cellular destinations, perhaps by fluidifying or buffering cholesterol in endosomal membranes, and that thioperamide has repurposing potential for the treatment of NPC.
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Affiliation(s)
- Dimitri Moreau
- Department of BiochemistryUniversity of GenevaGeneva 4Switzerland
| | - Fabrizio Vacca
- Department of BiochemistryUniversity of GenevaGeneva 4Switzerland
| | - Stefania Vossio
- Department of BiochemistryUniversity of GenevaGeneva 4Switzerland
| | - Cameron Scott
- Department of BiochemistryUniversity of GenevaGeneva 4Switzerland
| | | | | | - Charles Ferguson
- Institute for Molecular Bioscience and Center for Microscopy and MicroanalysisUniversity of QueenslandBrisbaneQldAustralia
| | - Markus Damme
- Biochemisches InstitutChristian‐Albrechts‐UniversitätKielGermany
| | - Marc Moniatte
- Mass Spectrometry Core FacilityEPFLLausanneSwitzerland
| | - Robert G Parton
- Institute for Molecular Bioscience and Center for Microscopy and MicroanalysisUniversity of QueenslandBrisbaneQldAustralia
| | | | - Jean Gruenberg
- Department of BiochemistryUniversity of GenevaGeneva 4Switzerland
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16
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Chen X, Winters C, Crocker V, Lazarou M, Sousa AA, Leapman RD, Reese TS. Identification of PSD-95 in the Postsynaptic Density Using MiniSOG and EM Tomography. Front Neuroanat 2018; 12:107. [PMID: 30581381 PMCID: PMC6292990 DOI: 10.3389/fnana.2018.00107] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 11/20/2018] [Indexed: 12/21/2022] Open
Abstract
Combining tomography with electron microscopy (EM) produces images at definition sufficient to visualize individual protein molecules or molecular complexes in intact neurons. When freeze-substituted hippocampal cultures in plastic sections are imaged by EM tomography, detailed structures emerging from 3D reconstructions reveal putative glutamate receptors and membrane-associated filaments containing scaffolding proteins such as postsynaptic density (PSD)-95 family proteins based on their size, shape, and known distributions. In limited instances, structures can be identified with enhanced immuno-Nanogold labeling after light fixation and subsequent freeze-substitution. Molecular identification of structure can be corroborated in their absence after acute protein knockdown or gene knockout. However, additional labeling methods linking EM level structure to molecules in tomograms are needed. A recent development for labeling structures for TEM employs expression of endogenous proteins carrying a green fluorescent tag, miniSOG, to photoconvert diaminobenzidine (DAB) into osmiophilic polymers. This approach requires initial mild chemical fixation but many of structural features in neurons can still be discerned in EM tomograms. The photoreaction product, which appears as electron-dense, fine precipitates decorating protein structures in neurons, may diffuse to fill cytoplasm of spines, thus obscuring specific localization of proteins tagged with miniSOG. Here we develop an approach to minimize molecular diffusion of the DAB photoreaction product in neurons, which allows miniSOG tagged molecule/complexes to be identified in tomograms. The examples reveal electron-dense clusters of reaction product labeling membrane-associated vertical filaments, corresponding to the site of miniSOG fused at the C-terminal end of PSD-95-miniSOG, allowing identification of PSD-95 vertical filaments at the PSD. This approach, which results in considerable improvement in the precision of labeling PSD-95 in tomograms without complications due to the presence of antibody complexes in immunogold labeling, may be applicable for identifying other synaptic proteins in intact neurons.
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Affiliation(s)
- Xiaobing Chen
- Laboratory of Neurobiology, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Christine Winters
- Laboratory of Neurobiology, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Virginia Crocker
- EM Facility, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Michael Lazarou
- Surgical Neurology Branch, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Alioscka A Sousa
- Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, United States
| | - Richard D Leapman
- Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, United States
| | - Thomas S Reese
- Laboratory of Neurobiology, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, United States
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17
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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: 20] [Impact Index Per Article: 3.3] [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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18
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Dietrich M, Malik MS, Nikolaysen F, Skeie M, Stang E. Protein kinase C mediated internalization of ErbB2 is independent of clathrin, ubiquitination and Hsp90 dissociation. Exp Cell Res 2018; 371:139-150. [PMID: 30098331 DOI: 10.1016/j.yexcr.2018.08.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 08/02/2018] [Accepted: 08/03/2018] [Indexed: 02/07/2023]
Abstract
Overexpression of ErbB2 is frequent in cancer and understanding the mechanisms which regulate its expression is important. ErbB2 is considered endocytosis resistant. It has no identified ligand, but upon heterodimerization it is a potent mediator of proliferative signaling. A recent study established a role for protein kinase C (PKC) in internalization and recycling of ErbB2. We have now further investigated the molecular mechanisms involved in PKC-mediated downregulation of ErbB2. We confirm that PMA-induced PKC activation causes ErbB2 internalization, but while the Hsp90 inhibitor 17-AAG induced ErbB2 degradation, PMA had no such effect. When combined with 17-AAG, PMA had additive effect on ErbB2 internalization indicating that Hsp90 inhibition and PKC activation induce internalization by alternative mechanisms. We confirm that while 17-AAG-induced internalization was clathrin-mediated, PMA-induced internalization was clathrin independent. This difference may be explained by while both 17-AAG and PMA reduced the constitutive tyrosine phosphorylation of ErbB2, only 17-AAG induced Hsp90 dissociation, Hsp70 recruitment and ubiquitination of ErbB2. Importantly, since PMA induced internalization of ErbB2, but not dissociation of Hsp90, Hsp90 does not per se retain ErbB2 at the plasma membrane. The morphology of the compartment into which receptors are sorted upon PKC activation has not previously been identified. By immuno-electron microscopy, we show that PMA sorts ErbB2 into a complex tubulovesicular or cisternal organelle resembling a previously described endocytic recycling compartment.
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Affiliation(s)
- Markus Dietrich
- Department of Pathology, Oslo University Hospital, Oslo, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | | | | | - Marianne Skeie
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Espen Stang
- Department of Pathology, Oslo University Hospital, Oslo, Norway.
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19
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Bertolin G, Bulteau AL, Alves-Guerra MC, Burel A, Lavault MT, Gavard O, Le Bras S, Gagné JP, Poirier GG, Le Borgne R, Prigent C, Tramier M. Aurora kinase A localises to mitochondria to control organelle dynamics and energy production. eLife 2018; 7:38111. [PMID: 30070631 PMCID: PMC6140714 DOI: 10.7554/elife.38111] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 08/01/2018] [Indexed: 12/18/2022] Open
Abstract
Many epithelial cancers show cell cycle dysfunction tightly correlated with the overexpression of the serine/threonine kinase Aurora A (AURKA). Its role in mitotic progression has been extensively characterised, and evidence for new AURKA functions emerges. Here, we reveal that AURKA is located and imported in mitochondria in several human cancer cell lines. Mitochondrial AURKA impacts on two organelle functions: mitochondrial dynamics and energy production. When AURKA is expressed at endogenous levels during interphase, it induces mitochondrial fragmentation independently from RALA. Conversely, AURKA enhances mitochondrial fusion and ATP production when it is over-expressed. We demonstrate that AURKA directly regulates mitochondrial functions and that AURKA over-expression promotes metabolic reprogramming by increasing mitochondrial interconnectivity. Our work paves the way to anti-cancer therapeutics based on the simultaneous targeting of mitochondrial functions and AURKA inhibition. Structures called mitochondria power cells by turning oxygen and sugar into chemical energy. Each cell can have thousands of mitochondria, which work together to supply changing energy demands. They can fuse together or break apart, forming networks that change size and produce different amounts of energy. Getting the balance right is crucial; if energy levels are too low, the cell will not be able to grow and divide. If energy levels are too high, the cell can grow at a faster rate, which can contribute to the cell becoming cancerous. Although we know that mitochondria provide energy, it is not clear how they communicate to fine-tune the supply. Some clues come from cancer cells that seem dependent on their mitochondria for survival. In these cells, levels of a protein called AURKA are higher than normal. AURKA helps cells to divide, and it interacts with many different proteins. This complexity makes it difficult to work out exactly what AURKA does, but it is possible that it plays a role in energy supply. Bertolin et al. have now investigated whether mitochondria use AURKA to communicate inside human breast cancer cells. Tagging AURKA proteins with a fluorescent marker revealed that it accumulates inside mitochondria. Once it gets there, AURKA changes the shape of the mitochondria, which has dramatic effects on their capacity to produce energy. At normal levels, AURKA causes the mitochondria to fragment, breaking apart into smaller pieces. This maintains their energy output at a normal level. If AURKA levels are too high, the mitochondria fuse together and produce more energy. This means AURKA could help to fuel fast-growing cancer cells. Current drugs that aim to treat cancer by blocking the activity of AURKA show poor results. This is partly due to the fact that the protein has so many different roles in the cell. Finding that AURKA affects mitochondria is the first step in understanding one of its unknown roles. It also suggests the possibility of developing new drugs to change how mitochondria make energy in cancer cells that contain high levels of AURKA.
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Affiliation(s)
- Giulia Bertolin
- CNRS, UMR 6290, Rennes, France.,Université de Rennes 1, UBL, Genetics and Development Institute of Rennes (IGDR), Rennes, France
| | - Anne-Laure Bulteau
- ENS de Lyon, Lyon, France.,CNRS UMR 5242, Lyon, France.,INRA USC 1370, Lyon, France
| | - Marie-Clotilde Alves-Guerra
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS, UMR 8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Agnes Burel
- Microscopy Rennes Imaging Centre, SFR Biosit, UMS CNRS 3480- US INSERM 018, Université de Rennes, Rennes, France
| | - Marie-Thérèse Lavault
- Microscopy Rennes Imaging Centre, SFR Biosit, UMS CNRS 3480- US INSERM 018, Université de Rennes, Rennes, France
| | - Olivia Gavard
- CNRS, UMR 6290, Rennes, France.,Université de Rennes 1, UBL, Genetics and Development Institute of Rennes (IGDR), Rennes, France.,Equipes labélisées Ligue Contre Le Cancer, Rennes, France.,Centre de recherche du CHU de Québec, Faculté de Médecine, Université Laval, Québec, Canada
| | - Stephanie Le Bras
- CNRS, UMR 6290, Rennes, France.,Université de Rennes 1, UBL, Genetics and Development Institute of Rennes (IGDR), Rennes, France
| | - Jean-Philippe Gagné
- Centre de recherche du CHU de Québec, Faculté de Médecine, Université Laval, Québec, Canada
| | - Guy G Poirier
- Centre de recherche du CHU de Québec, Faculté de Médecine, Université Laval, Québec, Canada
| | - Roland Le Borgne
- CNRS, UMR 6290, Rennes, France.,Université de Rennes 1, UBL, Genetics and Development Institute of Rennes (IGDR), Rennes, France.,Equipes labélisées Ligue Contre Le Cancer, Rennes, France
| | - Claude Prigent
- CNRS, UMR 6290, Rennes, France.,Université de Rennes 1, UBL, Genetics and Development Institute of Rennes (IGDR), Rennes, France.,Equipes labélisées Ligue Contre Le Cancer, Rennes, France
| | - Marc Tramier
- CNRS, UMR 6290, Rennes, France.,Université de Rennes 1, UBL, Genetics and Development Institute of Rennes (IGDR), Rennes, France.,Microscopy Rennes Imaging Centre, SFR Biosit, UMS CNRS 3480- US INSERM 018, Université de Rennes, Rennes, France
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20
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Ferguson S, Lucocq J. The invasive cell coat at the microsporidian Trachipleistophora hominis-host cell interface contains secreted hexokinases. Microbiologyopen 2018; 8:e00696. [PMID: 30051624 PMCID: PMC6460350 DOI: 10.1002/mbo3.696] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 06/22/2018] [Accepted: 06/25/2018] [Indexed: 02/04/2023] Open
Abstract
Microsporidia are obligate intracellular parasites causing significant disease in humans and economically important animals. In parallel to their extreme genetic reduction, Microsporidia have evolved novel mechanisms for exploiting host metabolism. A number of microsporidians confer secretion of otherwise cytosolic proteins by coding for signal peptides that direct entry into the endoplasmic reticulum. The human pathogen Trachipleistophora hominis encodes for four hexokinases, three of which have signal peptides at the N‐terminus. Here, we localized hexokinase 2 and hexokinase 3 through developmental stages of T. hominis using light and electron microscopy. Both proteins were concentrated in an extracellular coat previously termed the plaque matrix (PQM). The PQM (containing hexokinases) was morphologically dynamic, infiltrating the host cytoplasm predominantly during replicative stages. Throughout development the PQM interacted closely with endoplasmic reticulum that was demonstrated to be active in membrane protein biosynthesis and export. The impact of hexokinase on the host metabolism was probed using the fluorescent analog of glucose, 2‐NBDG, which displayed spatially restricted increases in signal intensity at the parasite/vacuole surface, coincident with hexokinase/PQM distribution. Gross metabolic aberrations, measured using metabolic profiling with the Seahorse XF Analyzer, were not detectable in mixed stage cocultures. Overall, these results highlight a role for the extended cell coat of T. hominis in host–parasite interactions, within which secreted hexokinases may work as part of a metabolic machine to increase glycolytic capacity or ATP generation close to the parasite surface.
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Affiliation(s)
- Sophie Ferguson
- Structural Cell Biology Group, School of Medicine, University of St Andrews, St Andrews, UK
| | - John Lucocq
- Structural Cell Biology Group, School of Medicine, University of St Andrews, St Andrews, UK
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21
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Abstract
Despite the improved resolution capacities of fluorescence microscopy over the last 20 years, localization of specific proteins at the ultrastructural level with gold-conjugated antibodies remains a valuable technique in the cell biological tool chest. Ultrastructural immunolocalization of specific proteins in tissues rather than in cultured cells is often advantageous because, in tissues, the interactions between different cell types and with the extracellular matrix are maintained. Here, we describe two immunogold labeling procedures to localize at the ultrastructural level one or more proteins. In the first procedure (pre-embedding), micrometer-thick tissue cryostat sections are immunostained prior to embedding for obtaining ultrathin sections suitable for TEM, while in the second procedure (post-embedding), tissues are embedded in a hydrophobic resin such as Lowicryl K4M and ultrathin sections are first obtained and then immunolabeled. While the former method is better at generating strong immunolabeling, the latter is better at preserving ultrastructure.
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22
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Three-Dimensional Imaging of Biological Tissue by Cryo X-Ray Ptychography. Sci Rep 2017; 7:6291. [PMID: 28740127 PMCID: PMC5524705 DOI: 10.1038/s41598-017-05587-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/31/2017] [Indexed: 12/16/2022] Open
Abstract
High-throughput three-dimensional cryogenic imaging of thick biological specimens is valuable for identifying biologically- or pathologically-relevant features of interest, especially for subsequent correlative studies. Unfortunately, high-resolution imaging techniques at cryogenic conditions often require sample reduction through sequential physical milling or sectioning for sufficient penetration to generate each image of the 3-D stack. This study represents the first demonstration of using ptychographic hard X-ray tomography at cryogenic temperatures for imaging thick biological tissue in a chemically-fixed, frozen-hydrated state without heavy metal staining and organic solvents. Applied to mammalian brain, this label-free cryogenic imaging method allows visualization of myelinated axons and sub-cellular features such as age-related pigmented cellular inclusions at a spatial resolution of ~100 nanometers and thicknesses approaching 100 microns. Because our approach does not require dehydration, staining or reduction of the sample, we introduce the possibility for subsequent analysis of the same tissue using orthogonal approaches that are expected to yield direct complementary insight to the biological features of interest.
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23
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Asadi J, Ferguson S, Raja H, Hacker C, Marius P, Ward R, Pliotas C, Naismith J, Lucocq J. Enhanced imaging of lipid rich nanoparticles embedded in methylcellulose films for transmission electron microscopy using mixtures of heavy metals. Micron 2017; 99:40-48. [PMID: 28419915 PMCID: PMC5465805 DOI: 10.1016/j.micron.2017.03.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 03/28/2017] [Accepted: 03/29/2017] [Indexed: 02/01/2023]
Abstract
Uranyl acetate/tungsten double stains are proposed for imaging lipid rich nanoparticle in TEM. Combined with methylcellulose embedment, the technique enhances membrane contrast. The technique works for liposomes, nanodiscs and bicelles. The double staining should improve quantification of lipid rich nanoparticles.
Synthetic and naturally occurring lipid-rich nanoparticles are of wide ranging importance in biomedicine. They include liposomes, bicelles, nanodiscs, exosomes and virus particles. The quantitative study of these particles requires methods for high-resolution visualization of the whole population. One powerful imaging method is cryo-EM of vitrified samples, but this is technically demanding, requires specialized equipment, provides low contrast and does not reveal all particles present in a population. Another approach is classical negative stain-EM, which is more accessible but is difficult to standardize for larger lipidic structures, which are prone to artifacts of structure collapse and contrast variability. A third method uses embedment in methylcellulose films containing uranyl acetate as a contrasting agent. Methylcellulose embedment has been widely used for contrasting and supporting cryosections but only sporadically for visualizing lipid rich vesicular structures such as endosomes and exosomes. Here we present a simple methylcellulose-based method for routine and comprehensive visualization of synthetic lipid rich nanoparticles preparations, such as liposomes, bicelles and nanodiscs. It combines a novel double-staining mixture of uranyl acetate (UA) and tungsten-based electron stains (namely phosphotungstic acid (PTA) or sodium silicotungstate (STA)) with methylcellulose embedment. While the methylcellulose supports the delicate lipid structures during drying, the addition of PTA or STA to UA provides significant enhancement in lipid structure display and contrast as compared to UA alone. This double staining method should aid routine structural evaluation and quantification of lipid rich nanoparticles structures.
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Affiliation(s)
- Jalal Asadi
- School of Medicine, University of St Andrews, St. Andrews, Fife, KY16 9TF, UK
| | - Sophie Ferguson
- School of Medicine, University of St Andrews, St. Andrews, Fife, KY16 9TF, UK
| | - Hussain Raja
- School of Medicine, University of St Andrews, St. Andrews, Fife, KY16 9TF, UK
| | - Christian Hacker
- School of Medicine, University of St Andrews, St. Andrews, Fife, KY16 9TF, UK
| | - Phedra Marius
- Biomedical Sciences Research Complex, North Haugh, University of St. Andrews, St. Andrews, Scotland, UK
| | - Richard Ward
- Biomedical Sciences Research Complex, North Haugh, University of St. Andrews, St. Andrews, Scotland, UK
| | - Christos Pliotas
- Biomedical Sciences Research Complex, North Haugh, University of St. Andrews, St. Andrews, Scotland, UK
| | - James Naismith
- Biomedical Sciences Research Complex, North Haugh, University of St. Andrews, St. Andrews, Scotland, UK
| | - John Lucocq
- School of Medicine, University of St Andrews, St. Andrews, Fife, KY16 9TF, UK.
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24
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Short AR, Czeisler C, Stocker B, Cole S, Otero JJ, Winter JO. Imaging Cell-Matrix Interactions in 3D Collagen Hydrogel Culture Systems. Macromol Biosci 2017; 17. [PMID: 28221720 DOI: 10.1002/mabi.201600478] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 01/11/2017] [Indexed: 01/15/2023]
Abstract
3D hydrogels better replicate in vivo conditions, and yield different results from 2D substrates. However, imaging interactions between cells and the hydrogel microenvironment is challenging because of light diffraction and poor focal depth. Here, cryosectioning and vibrating microtomy methods and fixation protocols are compared. Collagen I/III hydrogel sections (20-100 µm) are fixed with paraformaldehyde (2%-4%) and structurally evaluated. Cryosectioning damaged hydrogels, and vibrating microtomy (100 µm, 2%) yielded the best preservation of microstructure and cell integrity. These results demonstrate a potential processing method that preserves hydrogel and cell integrity, permitting imaging of cell interactions with the microenvironment.
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Affiliation(s)
- Aaron R Short
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH, 43210, USA
| | - Catherine Czeisler
- Department of Pathology and the Neurological Research Institute, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Benjamin Stocker
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH, 43210, USA
| | - Sara Cole
- Campus Microscopy and Imaging Facility, The Ohio State University, Columbus, OH, 43210, USA
| | - José Javier Otero
- Department of Pathology and the Neurological Research Institute, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Jessica O Winter
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH, 43210, USA.,William G. Lowrie Department of Chemical and Biomolecular Engineering, College of Engineering, The Ohio State University, Columbus, OH, 43210, USA
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25
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Bhreathnach U, Griffin B, Brennan E, Ewart L, Higgins D, Murphy M. Profibrotic IHG-1 complexes with renal disease associated HSPA5 and TRAP1 in mitochondria. Biochim Biophys Acta Mol Basis Dis 2017; 1863:896-906. [PMID: 28115289 DOI: 10.1016/j.bbadis.2017.01.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 01/17/2017] [Accepted: 01/19/2017] [Indexed: 01/01/2023]
Abstract
The highly conserved mitochondrial protein induced in high glucose-1 (IHG-1) functions to maintain mitochondrial quality and is associated with the development of fibrosis in diabetic nephropathy. Towards identifying novel approaches to treating diabetic kidney disease, IHG-1-protein-protein interactions were investigated using epitope-tagged immunoprecipitation analyses followed by mass spectrometry. Here we show that IHG-1 is solely expressed in mitochondria and localised to the inner mitochondrial membrane, the region where mitochondrial reactive oxygen species are generated. Chaperones HSPA5 and TRAP1 and cold shock protein YBX1 were identified as IHG-1 binding partners. All three proteins are important in the cellular response to oxidative stress and play important roles in mitochondrial transcription and DNA repair. Both redox imbalance and IHG-1 stimulate TGF-β signalling. IHG-1, HSPA5 and YBX1 all show increased expression in diabetic nephropathy, chronic kidney disease and in the Unilateral Ureteral Obstruction model of kidney fibrosis. Increased IHG-1 expression in UUO correlated with loss of TRAP1 expression. IHG-1 may target TRAP1 for degradation. When IHG-1 is no longer localised to mitochondria, it retains the ability to interact with the cold shock protein YBX1, facilitating anti-fibrotic actions in the nucleus. Targeting these proteins may offer alternative treatments for fibrotic kidney disease.
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Affiliation(s)
- Una Bhreathnach
- Conway Institute, School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Brenda Griffin
- Conway Institute, School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Eoin Brennan
- Conway Institute, School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Leah Ewart
- Conway Institute, School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Debra Higgins
- Conway Institute, School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Madeline Murphy
- Conway Institute, School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
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26
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Freibert SA, Goldberg AV, Hacker C, Molik S, Dean P, Williams TA, Nakjang S, Long S, Sendra K, Bill E, Heinz E, Hirt RP, Lucocq JM, Embley TM, Lill R. Evolutionary conservation and in vitro reconstitution of microsporidian iron-sulfur cluster biosynthesis. Nat Commun 2017; 8:13932. [PMID: 28051091 PMCID: PMC5216125 DOI: 10.1038/ncomms13932] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 11/14/2016] [Indexed: 12/22/2022] Open
Abstract
Microsporidians are obligate intracellular parasites that have minimized their genome content and sub-cellular structures by reductive evolution. Here, we demonstrate that cristae-deficient mitochondria (mitosomes) of Trachipleistophora hominis are the functional site of iron–sulfur cluster (ISC) assembly, which we suggest is the essential task of these organelles. Cell fractionation, fluorescence imaging and immunoelectron microscopy demonstrate that mitosomes contain a complete pathway for [2Fe–2S] cluster biosynthesis that we biochemically reconstituted using purified mitosomal ISC proteins. The T. hominis cytosolic iron–sulfur protein assembly (CIA) pathway includes the essential Cfd1–Nbp35 scaffold complex that assembles a [4Fe–4S] cluster as shown by spectroscopic methods in vitro. Phylogenetic analyses reveal that the ISC and CIA pathways are predominantly bacterial, but their cytosolic and nuclear target Fe/S proteins are mainly archaeal. This mixed evolutionary history of Fe/S-related proteins and pathways, and their strong conservation among highly reduced parasites, provides compelling evidence for the ancient chimeric ancestry of eukaryotes.
The functions of the highly reduced mitochondria (mitosomes) of microsporidians are not well-characterized. Here, the authors show that the Trachipleistophora hominis mitosome is the site of iron–sulfur cluster assembly and that its retention is likely linked to its role in cytosolic and nuclear iron–sulfur protein maturation.
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Affiliation(s)
- Sven-A Freibert
- Institut für Zytobiologie und Zytopathologie, Philipps-Universität, Robert-Koch-Strasse 6, Marburg 35032, Germany
| | - Alina V Goldberg
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK
| | - Christian Hacker
- School of Medicine, University of St Andrews, St. Andrews KY16 9TF, UK.,Bioimaging Centre, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Sabine Molik
- Institut für Zytobiologie und Zytopathologie, Philipps-Universität, Robert-Koch-Strasse 6, Marburg 35032, Germany
| | - Paul Dean
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK
| | - Tom A Williams
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK
| | - Sirintra Nakjang
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK
| | - Shaojun Long
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK
| | - Kacper Sendra
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK
| | - Eckhard Bill
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, Mülheim an der Ruhr 45470, Germany
| | - Eva Heinz
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK
| | - Robert P Hirt
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK
| | - John M Lucocq
- School of Medicine, University of St Andrews, St. Andrews KY16 9TF, UK
| | - T Martin Embley
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK
| | - Roland Lill
- Institut für Zytobiologie und Zytopathologie, Philipps-Universität, Robert-Koch-Strasse 6, Marburg 35032, Germany.,LOEWE Zentrum für Synthetische Mikrobiologie SynMikro, Hans-Meerwein-Strasse, Marburg 35043, Germany
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27
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Griffiths G, Slot JW, Webster P. Kiyoteru Tokuyasu: a pioneer of cryo-ultramicrotomy. J Microsc 2016; 260:235-7. [PMID: 26769194 DOI: 10.1111/jmi.12346] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 10/02/2015] [Indexed: 11/28/2022]
Abstract
In July 2015 Professor K.T. Tokuyasu passed away in San Diego giving us the opportunity to reflect on the contribution this electron microscopist made to the field of immunocytochemistry. His work provided a sensitive, minimally invasive approach to producing thin sections of biological material for labeling with antibodies. His approach has been applied to a wide range of biological applications and provided important information on cellular processes.
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Affiliation(s)
| | - Jan-Willem Slot
- Department of Cell Biology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Paul Webster
- Oak Crest Institute of Science, Monrovia, California, U.S.A
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28
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Topographic contrast of ultrathin cryo-sections for correlative super-resolution light and electron microscopy. Sci Rep 2016; 6:34062. [PMID: 27666401 PMCID: PMC5036093 DOI: 10.1038/srep34062] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 09/07/2016] [Indexed: 01/19/2023] Open
Abstract
Fluorescence microscopy reveals molecular expression at nanometer resolution but lacks ultrastructural context information. This deficit often hinders a clear interpretation of results. Electron microscopy provides this contextual subcellular detail, but protein identification can often be problematic. Correlative light and electron microscopy produces complimentary information that expands our knowledge of protein expression in cells and tissue. Inherent methodological difficulties are however encountered when combining these two very different microscopy technologies. We present a quick, simple and reproducible method for protein localization by conventional and super-resolution light microscopy combined with platinum shadowing and scanning electron microscopy to obtain topographic contrast from the surface of ultrathin cryo-sections. We demonstrate protein distribution at nuclear pores and at mitochondrial and plasma membranes in the extended topographical landscape of tissue.
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29
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Griffiths G, Slot JW, Webster P. Kiyoteru Tokuyasu: a pioneer of cryo-ultramicrotomy. Microscopy (Oxf) 2016; 64:377-9. [PMID: 26660733 DOI: 10.1093/jmicro/dfv351] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
| | - Jan-Willem Slot
- Department of Cell Biology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Paul Webster
- Oak Crest Institute of Science, Monrovia, CA, USA
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30
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Abstract
The objective of this study is to confirm the precise glucose transporter (GLUT) 8 localization and determine the expression of GLUT9a and GLUT9b by Western blot and confocal and immunoelectron microscopy in the mouse testis and sperm. GLUT8, GLUT9a, and GLUT9b proteins are expressed in the most intraseminiferous tubula cells and Leydig cells. GLUT8 localizes in the midpiece and principal piece as well as in the acrosomal region of the sperm. Immunoelectron microscopic analysis shows that GLUT8 is strongly detectable at the acrosome and neck region of the sperm. In the midpiece, GLUT8 localizes at the outer dense fibers (odf) as well as at the circumference of the spiral mitochondria. In the principal piece, GLUT8 localizes at the odf. GLUT9a strictly localizes in the midpiece, but GLUT9b localizes in the acrosome, midpiece, and principal piece of the sperm. These results suggest that glucose uptake via GLUT8, GLUT9a, and GLUT9b likely affects normal spermatogenesis, steroidogenesis, and sperm function in the mouse.
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Affiliation(s)
- Sung Tae Kim
- Department of Obstetrics and Gynecology,Washington University in St Louis, St Louis, Missouri 63110, USA
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31
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Szymanska M, Fosdahl AM, Nikolaysen F, Pedersen MW, Grandal MM, Stang E, Bertelsen V. A combination of two antibodies recognizing non-overlapping epitopes of HER2 induces kinase activity-dependent internalization of HER2. J Cell Mol Med 2016; 20:1999-2011. [PMID: 27469139 PMCID: PMC5020627 DOI: 10.1111/jcmm.12899] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 05/06/2016] [Indexed: 12/14/2022] Open
Abstract
The human epidermal growth factor receptor 2 (HER2/ErbB2) is overexpressed in a number of human cancers. HER2 is the preferred heterodimerization partner for other epidermal growth factor receptor (EGFR) family members and is considered to be resistant to endocytic down-regulation, properties which both contribute to the high oncogenic potential of HER2. Antibodies targeting members of the EGFR family are powerful tools in cancer treatment and can function by blocking ligand binding, preventing receptor dimerization, inhibiting receptor activation and/or inducing receptor internalization and degradation. With respect to antibody-induced endocytosis of HER2, various results are reported, and the effect seems to depend on the HER2 expression level and whether antibodies are given as individual antibodies or as mixtures of two or more. In this study, the effect of a mixture of two monoclonal antibodies against non-overlapping epitopes of HER2 was investigated with respect to localization and stability of HER2. Individual antibodies had limited effect, but the combination of antibodies induced internalization and degradation of HER2 by multiple endocytic pathways. In addition, HER2 was phosphorylated and ubiquitinated upon incubation with the antibody combination, and the HER2 kinase activity was found to be instrumental in antibody-induced HER2 down-regulation.
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Affiliation(s)
- Monika Szymanska
- Department of Pathology, Oslo University Hospital, Oslo, Norway.,Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Anne M Fosdahl
- Department of Pathology, Oslo University Hospital, Oslo, Norway.,Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Filip Nikolaysen
- Department of Pathology, Oslo University Hospital, Oslo, Norway.,Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | | | | | - Espen Stang
- Department of Pathology, Oslo University Hospital, Oslo, Norway
| | - Vibeke Bertelsen
- Department of Pathology, Oslo University Hospital, Oslo, Norway.
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32
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Nanoparticle suspensions enclosed in methylcellulose: a new approach for quantifying nanoparticles in transmission electron microscopy. Sci Rep 2016; 6:25275. [PMID: 27141843 PMCID: PMC4855187 DOI: 10.1038/srep25275] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 04/14/2016] [Indexed: 01/13/2023] Open
Abstract
Nanoparticles are of increasing importance in biomedicine but quantification is problematic because current methods depend on indirect measurements at low resolution. Here we describe a new high-resolution method for measuring and quantifying nanoparticles in suspension. It involves premixing nanoparticles in a hydrophilic support medium (methylcellulose) before introducing heavy metal stains for visualization in small air-dried droplets by transmission electron microscopy (TEM). The use of methylcellulose avoids artifacts of conventional negative stain-TEM by (1) restricting interactions between the nanoparticles, (2) inhibiting binding to the specimen support films and (3) reducing compression after drying. Methylcellulose embedment provides effective electron imaging of liposomes, nanodiscs and viruses as well as comprehensive visualization of nanoparticle populations in droplets of known size. These qualities facilitate unbiased sampling, rapid size measurement and estimation of nanoparticle numbers by means of ratio counting using a colloidal gold calibrant. Specimen preparation and quantification take minutes and require a few microliters of sample using only basic laboratory equipment and a standard TEM.
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33
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Munson MJ, Allen GF, Toth R, Campbell DG, Lucocq JM, Ganley IG. mTOR activates the VPS34-UVRAG complex to regulate autolysosomal tubulation and cell survival. EMBO J 2015; 34:2272-90. [PMID: 26139536 PMCID: PMC4585463 DOI: 10.15252/embj.201590992] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Revised: 05/16/2015] [Accepted: 06/04/2015] [Indexed: 02/01/2023] Open
Abstract
Lysosomes are essential organelles that function to degrade and recycle unwanted, damaged and toxic biological components. Lysosomes also act as signalling platforms in activating the nutrient-sensing kinase mTOR. mTOR regulates cellular growth, but it also helps to maintain lysosome identity by initiating lysosomal tubulation through a process termed autophagosome-lysosome reformation (ALR). Here we identify a lysosomal pool of phosphatidylinositol 3-phosphate that, when depleted by specific inhibition of the class III phosphoinositide 3-kinase VPS34, results in prolonged lysosomal tubulation. This tubulation requires mTOR activity, and we identified two direct mTOR phosphorylation sites on UVRAG (S550 and S571) that activate VPS34. Loss of these phosphorylation sites reduced VPS34 lipid kinase activity and resulted in an increase in number and length of lysosomal tubules. In cells in which phosphorylation at these UVRAG sites is disrupted, the result of impaired lysosomal tubulation alongside ALR activation is massive cell death. Our data imply that ALR is critical for cell survival under nutrient stress and that VPS34 is an essential regulatory element in this process.
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Affiliation(s)
- Michael J Munson
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences University of Dundee, Dundee, UK
| | - George Fg Allen
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences University of Dundee, Dundee, UK
| | - Rachel Toth
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences University of Dundee, Dundee, UK
| | - David G Campbell
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences University of Dundee, Dundee, UK
| | - John M Lucocq
- School of Medicine University of St Andrews, St Andrews, UK
| | - Ian G Ganley
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences University of Dundee, Dundee, UK
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34
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Rønning SB, Carlson CR, Stang E, Kolset SO, Hollung K, Pedersen ME. Syndecan-4 Regulates Muscle Differentiation and Is Internalized from the Plasma Membrane during Myogenesis. PLoS One 2015; 10:e0129288. [PMID: 26068620 PMCID: PMC4467083 DOI: 10.1371/journal.pone.0129288] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 05/06/2015] [Indexed: 12/31/2022] Open
Abstract
The cell surface proteoglycan syndecan-4 has been reported to be crucial for muscle differentiation, but the molecular mechanisms still remain to be fully understood. During in vitro differentiation of bovine muscle cells immunocytochemical analyses showed strong labelling of syndecan-4 intracellularly, in close proximity with Golgi structures, in membranes of intracellular vesicles and finally, in the nuclear area including the nuclear envelope. Chase experiments showed that syndecan-4 was internalized from the plasma membrane during this process. Furthermore, when syndecan-4 was knocked down by siRNA more myotubes were formed, and the expression of myogenic transcription factors, β1-integrin and actin was influenced. However, when bovine muscle cells were treated with a cell-penetrating peptide containing the cytoplasmic region of syndecan-4, myoblast fusion and thus myotube formation was blocked, both in normal cells and in syndecan-4 knock down cells. Altogether this suggests that the cytoplasmic domain of syndecan-4 is important in regulation of myogenesis. The internalization of syndecan-4 from the plasma membrane during muscle differentiation and the nuclear localization of syndecan-4 in differentiated muscle cells may be part of this regulation, and is a novel aspect of syndecan biology which merits further studies.
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Affiliation(s)
| | - Cathrine R. Carlson
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, Oslo, Norway
| | - Espen Stang
- Department of Pathology, Oslo University Hospital, Rikshospitalet, P.O. Box 4950 Nydalen, 0424 Oslo, Norway
| | - Svein O. Kolset
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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35
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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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36
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Ferrera D, Canale C, Marotta R, Mazzaro N, Gritti M, Mazzanti M, Capellari S, Cortelli P, Gasparini L. Lamin B1 overexpression increases nuclear rigidity in autosomal dominant leukodystrophy fibroblasts. FASEB J 2014; 28:3906-18. [PMID: 24858279 PMCID: PMC4139899 DOI: 10.1096/fj.13-247635] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 05/12/2014] [Indexed: 12/22/2022]
Abstract
The architecture and structural mechanics of the cell nucleus are defined by the nuclear lamina, which is formed by A- and B-type lamins. Recently, gene duplication and protein overexpression of lamin B1 (LB1) have been reported in pedigrees with autosomal dominant leukodystrophy (ADLD). However, how the overexpression of LB1 affects nuclear mechanics and function and how it may result in pathology remain unexplored. Here, we report that in primary human skin fibroblasts derived from ADLD patients, LB1, but not other lamins, is overexpressed at the nuclear lamina and specifically enhances nuclear stiffness. Transient transfection of LB1 in HEK293 and neuronal N2a cells mimics the mechanical phenotype of ADLD nuclei. Notably, in ADLD fibroblasts, reducing LB1 protein levels by shRNA knockdown restores elasticity values to those indistinguishable from control fibroblasts. Moreover, isolated nuclei from ADLD fibroblasts display a reduced nuclear ion channel open probability on voltage-step application, suggesting that biophysical changes induced by LB1 overexpression may alter nuclear signaling cascades in somatic cells. Overall, the overexpression of LB1 in ADLD cells alters nuclear mechanics and is linked to changes in nuclear signaling, which could help explain the pathogenesis of this disease.
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Affiliation(s)
| | | | - Roberto Marotta
- Department of Nanochemistry, Istituto Italiano di Tecnologia, Genoa, Italy
| | | | - Marta Gritti
- Department of Biosciences, University of Milano, Milan, Italy
| | | | - Sabina Capellari
- Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto delle Scienze Neurologiche di Bologna, Clinica Neurologica, Ospedale Bellaria, Bologna, Italy; and Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Pietro Cortelli
- Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto delle Scienze Neurologiche di Bologna, Clinica Neurologica, Ospedale Bellaria, Bologna, Italy; and Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
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Webster P, Webster A. Cryosectioning fixed and cryoprotected biological material for immunocytochemistry. Methods Mol Biol 2014; 1117:273-313. [PMID: 24357368 DOI: 10.1007/978-1-62703-776-1_13] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Immunocytochemistry for electron microscopy provides important information on the location and relative abundance of proteins inside cells. Gaining access to this information without extracting or disrupting the location of target proteins requires specialized preparation methods. Sectioning frozen blocks of chemically fixed and cryoprotected biological material is one method for obtaining immunocytochemical data. Once the cells or tissues are cut, the cryosections are thawed, mounted onto coated grids, and labeled with specific antibodies and colloidal gold probes. They are then embedded in a thin film of plastic containing a contrasting agent. Subcellular morphology can then be correlated with specific affinity labeling by examination in the transmission electron microscope (TEM). The major advantage of using thawed cryosections for immunolabeling is that the sections remain fully hydrated through the immunolabeling steps, reducing the possibility of dehydration-induced antigen modification. Modern technical advancements both in preparation protocols and equipment design make cryosectioning a routine and rapid approach for immunocytochemistry that may provide increased sensitivity for some antibodies.
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Affiliation(s)
- Paul Webster
- Center for Electron Microscopy and Microanalysis (CEMMA), University of Souther California, Los Angeles, CA, USA
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Kopek BG, Shtengel G, Grimm JB, Clayton DA, Hess HF. Correlative photoactivated localization and scanning electron microscopy. PLoS One 2013; 8:e77209. [PMID: 24204771 PMCID: PMC3808397 DOI: 10.1371/journal.pone.0077209] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 09/03/2013] [Indexed: 11/26/2022] Open
Abstract
The ability to localize proteins precisely within subcellular space is crucial to understanding the functioning of biological systems. Recently, we described a protocol that correlates a precise map of fluorescent fusion proteins localized using three-dimensional super-resolution optical microscopy with the fine ultrastructural context of three-dimensional electron micrographs. While it achieved the difficult simultaneous objectives of high photoactivated fluorophore preservation and ultrastructure preservation, it required a super-resolution optical and specialized electron microscope that is not available to many researchers. We present here a faster and more practical protocol with the advantage of a simpler two-dimensional optical (Photoactivated Localization Microscopy (PALM)) and scanning electron microscope (SEM) system that retains the often mutually exclusive attributes of fluorophore preservation and ultrastructure preservation. As before, cryosections were prepared using the Tokuyasu protocol, but the staining protocol was modified to be amenable for use in a standard SEM without the need for focused ion beam ablation. We show the versatility of this technique by labeling different cellular compartments and structures including mitochondrial nucleoids, peroxisomes, and the nuclear lamina. We also demonstrate simultaneous two-color PALM imaging with correlated electron micrographs. Lastly, this technique can be used with small-molecule dyes as demonstrated with actin labeling using phalloidin conjugated to a caged dye. By retaining the dense protein labeling expected for super-resolution microscopy combined with ultrastructural preservation, simplifying the tools required for correlative microscopy, and expanding the number of useful labels we expect this method to be accessible and valuable to a wide variety of researchers.
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Affiliation(s)
- Benjamin G. Kopek
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America
- * E-mail:
| | - Gleb Shtengel
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America
| | - Jonathan B. Grimm
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America
| | - David A. Clayton
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America
| | - Harald F. Hess
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America
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39
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Autophagosomes form at ER-mitochondria contact sites. Nature 2013; 495:389-93. [PMID: 23455425 DOI: 10.1038/nature11910] [Citation(s) in RCA: 1269] [Impact Index Per Article: 115.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 01/15/2013] [Indexed: 12/13/2022]
Abstract
Autophagy is a tightly regulated intracellular bulk degradation/recycling system that has fundamental roles in cellular homeostasis. Autophagy is initiated by isolation membranes, which form and elongate as they engulf portions of the cytoplasm and organelles. Eventually isolation membranes close to form double membrane-bound autophagosomes and fuse with lysosomes to degrade their contents. The physiological role of autophagy has been determined since its discovery, but the origin of autophagosomal membranes has remained unclear. At present, there is much controversy about the organelle from which the membranes originate--the endoplasmic reticulum (ER), mitochondria and plasma membrane. Here we show that autophagosomes form at the ER-mitochondria contact site in mammalian cells. Imaging data reveal that the pre-autophagosome/autophagosome marker ATG14 (also known as ATG14L) relocalizes to the ER-mitochondria contact site after starvation, and the autophagosome-formation marker ATG5 also localizes at the site until formation is complete. Subcellular fractionation showed that ATG14 co-fractionates in the mitochondria-associated ER membrane fraction under starvation conditions. Disruption of the ER-mitochondria contact site prevents the formation of ATG14 puncta. The ER-resident SNARE protein syntaxin 17 (STX17) binds ATG14 and recruits it to the ER-mitochondria contact site. These results provide new insight into organelle biogenesis by demonstrating that the ER-mitochondria contact site is important in autophagosome formation.
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Karreman MA, Van Donselaar EG, Agronskaia AV, Verrips CT, Gerritsen HC. Novel contrasting and labeling procedures for correlative microscopy of thawed cryosections. J Histochem Cytochem 2012; 61:236-47. [PMID: 23264637 DOI: 10.1369/0022155412473756] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
One of the major challenges for correlative microscopy is the preparation of the sample; the protocols for transmission electron microscopy (TEM) and fluorescence microscopy (FM) often prove to be incompatible. Here, we introduce 2+Staining: an improved contrasting procedure for Tokuyasu sections that yields both excellent positive membrane contrast in the TEM and bright fluorescence of the probe labeled on the section. 2+Staining involves the contrasting of the immunolabeled sections with 1% osmium tetroxide, 2% uranyl acetate and lead citrate in sequential steps, followed by embedding in 1.8% methyl cellulose. In addition, we demonstrate an amplification of the fluorescent signal by introducing additional antibody incubation steps to the immunolabeling procedure. The methods were validated using the integrated laser and electron microscope (iLEM), a novel tool for correlative microscopy combining FM and TEM in a single setup. The approaches were tested on HL-60 cells labeled for lysosomal-associated membrane protein 2 (LAMP-2) and on sections of muscle from a facioscapulohumeral dystrophy mouse model. Yielding excellent results and greatly expediting the workflow, the methods are of great value for those working in the field of correlative microscopy and indispensible for future users of integrated correlative microscopy.
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Cetuximab in combination with anti-human IgG antibodies efficiently down-regulates the EGF receptor by macropinocytosis. Exp Cell Res 2012; 318:2578-91. [PMID: 22975728 DOI: 10.1016/j.yexcr.2012.09.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 08/31/2012] [Accepted: 09/04/2012] [Indexed: 02/05/2023]
Abstract
The monoclonal antibody C225 (Cetuximab) blocks binding of ligand to the epidermal growth factor receptor (EGFR). In addition, it is known that incubation with C225 induces endocytosis of the EGFR. This endocytosis has previously been shown to be increased when C225 is combined with an additional monoclonal anti-EGFR antibody. However, the effects of antibody combinations on EGFR activation, endocytosis, trafficking and degradation have been unclear. By binding a secondary antibody to the C225-EGFR complex, we here demonstrate that a combination of antibodies can efficiently internalize and degrade the EGFR. Although the combination of antibodies activated the EGFR kinase and induced ubiquitination of the EGFR, the kinase activity was not required for internalization of the EGFR. In contrast to EGF-induced EGFR down-regulation, the antibody combination efficiently degraded the EGFR without initiating downstream proliferative signaling. The antibody-induced internalization of EGFR was found not to depend on clathrin and/or dynamin, but depended on actin polymerization, suggesting induction of macropinocytosis. Macropinocytosis may cause internalization of large membrane areas, and this could explain the highly efficient internalization of the EGFR induced by combination of antibodies.
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Hol J, Otterdal K, Breland UM, Stang E, Pedersen TM, Hagelsteen K, Ranheim T, Kasprzycka M, Halvorsen B, Haraldsen G, Aukrust P. Statins affect the presentation of endothelial chemokines by targeting to multivesicular bodies. PLoS One 2012; 7:e40673. [PMID: 22815786 PMCID: PMC3398041 DOI: 10.1371/journal.pone.0040673] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 06/12/2012] [Indexed: 11/18/2022] Open
Abstract
Background In addition to lowering cholesterol, statins are thought to beneficially modulate inflammation. Several chemokines including CXCL1/growth-related oncogene (GRO)-α, CXCL8/interleukin (IL)-8 and CCL2/monocyte chemoattractant protein (MCP)-1 are important in the pathogenesis of atherosclerosis and can be influenced by statin-treatment. Recently, we observed that atorvastatintreatment alters the intracellular content and subcellular distribution of GRO-α in cultured human umbilical vein endothelial cells (HUVECs). The objective of this study was to investigate the mechanisms involved in this phenomenon. Methodology/ Principal Findings The effect of atorvastatin on secretion levels and subcellular distribution of GRO-α, IL-8 and MCP-1 in HUVECs activated by interleukin (IL)-1β were evaluated by ELISA, confocal microscopy and immunoelectron microscopy. Atorvastatin increased the intracellular contents of GRO-α, IL-8, and MCP-1 and induced colocalization with E-selectin in multivesicular bodies. This effect was prevented by adding the isoprenylation substrate GGPP, but not the cholesterol precursor squalene, indicating that atorvastatin exerts these effects by inhibiting isoprenylation rather than depleting the cells of cholesterol. Conclusions/ Significance Atorvastatin targets inflammatory chemokines to the endocytic pathway and multivesicular bodies and may contribute to explain the anti-inflammatory effect of statins at the level of endothelial cell function.
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Affiliation(s)
- Johanna Hol
- Division of Pathology, Oslo University Hospital, Oslo, Norway
| | - Kari Otterdal
- Research Institute for Internal Medicine, Oslo University Hospital, Oslo, Norway
| | - Unni M. Breland
- Research Institute for Internal Medicine, Oslo University Hospital, Oslo, Norway
| | - Espen Stang
- Division of Pathology, Oslo University Hospital, Oslo, Norway
| | - Turid M. Pedersen
- Research Institute for Internal Medicine, Oslo University Hospital, Oslo, Norway
| | | | - Trine Ranheim
- Research Institute for Internal Medicine, Oslo University Hospital, Oslo, Norway
| | | | - Bente Halvorsen
- Research Institute for Internal Medicine, Oslo University Hospital, Oslo, Norway
| | - Guttorm Haraldsen
- Division of Pathology, Oslo University Hospital, Oslo, Norway
- * E-mail:
| | - Pål Aukrust
- Research Institute for Internal Medicine, Oslo University Hospital, Oslo, Norway
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Schimak MP, Toenshoff ER, Bright M. Simultaneous 16S and 18S rRNA fluorescence in situ hybridization (FISH) on LR White sections demonstrated in Vestimentifera (Siboglinidae) tubeworms. Acta Histochem 2012; 114:122-30. [PMID: 21507466 PMCID: PMC3278570 DOI: 10.1016/j.acthis.2011.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 03/18/2011] [Accepted: 03/20/2011] [Indexed: 12/01/2022]
Abstract
Traditional morphological identification of invertebrate marine species is limited in early life history stages for many taxa. In this study, we demonstrate, by example of Vestimentiferan tubeworms (Siboglinidae, Polychaeta), that the simultaneous fluorescence in situ hybridization (FISH) of both eukaryotic host and bacterial symbiont cells is possible on a single semi-thin (1 μm) section. This allows the identification of host specimens to species level as well as offering visualization of bacteria distributed within the host tissue. Previously published 18S rRNA host-specific oligonucleotide probes for Riftia pachyptila, Tevnia jerichonana and a newly designed Oasisia alvinae probe, as well as a 16S rRNA probe targeting symbionts found in all host species, were applied. A number of standard fixation and hybridization parameters were tested and optimized for the best possible signal intensity and cellular resolution. Ethanol conserved samples embedded in LR White low viscosity resin yielded the best results with regard to both signal intensity and resolution. We show that extended storage times of specimens does not affect the quality of signals attained by FISH and use our protocol to identify morphologically unidentifiable tubeworm individuals from a small data set, conforming to previous findings in succession studies of the Siboglinidae family.
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Affiliation(s)
- Mario P Schimak
- University of Vienna, Department of Marine Biology, Austria.
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The future is cold: cryo-preparation methods for transmission electron microscopy of cells. Biol Cell 2011; 103:405-20. [PMID: 21812762 DOI: 10.1042/bc20110015] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Our knowledge of the organization of the cell is linked, to a great extent, to light and electron microscopy. Choosing either photons or electrons for imaging has many consequences on the image obtained, as well as on the experiment required in order to generate the image. One apparent effect on the experimental side is in the sample preparation, which can be quite elaborate for electron microscopy. In recent years, rapid freezing, cryo-preparation and cryo-electron microscopy have been more widely used because they introduce fewer artefacts during preparation when compared with chemical fixation and room temperature processing. In addition, cryo-electron microscopy allows the visualization of the hydrated specimens. In the present review, we give an introduction to the rapid freezing of biological samples and describe the preparation steps. We focus on bulk samples that are too big to be directly viewed under the electron microscope. Furthermore, we discuss the advantages and limitations of freeze substitution and cryo-electron microscopy of vitreous sections and compare their application to the study of bacteria and mammalian cells and to tomography.
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TICHELAAR W, FERGUSON C, OLIVO JC, LEONARD KR, HAIDER M. A novel method of Z-contrast imaging in STEM applied to double-labelling. J Microsc 2011. [DOI: 10.1111/j.1365-2818.1994.tb04783.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Brankatschk B, Pons V, Parton RG, Gruenberg J. Role of SNX16 in the dynamics of tubulo-cisternal membrane domains of late endosomes. PLoS One 2011; 6:e21771. [PMID: 21754999 PMCID: PMC3130770 DOI: 10.1371/journal.pone.0021771] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 06/07/2011] [Indexed: 11/18/2022] Open
Abstract
In this paper, we report that the PX domain-containing protein SNX16, a member of the sorting nexin family, is associated with late endosome membranes. We find that SNX16 is selectively enriched on tubulo-cisternal elements of this membrane system, whose highly dynamic properties and formation depend on intact microtubules. By contrast, SNX16 was not found on vacuolar elements that typically contain LBPA, and thus presumably correspond to multivesicular endosomes. We conclude that SNX16, together with its partner phosphoinositide, define a highly dynamic subset of late endosomal membranes, supporting the notion that late endosomes are organized in distinct morphological and functional regions. Our data also indicate that SNX16 is involved in tubule formation and cholesterol transport as well as trafficking of the tetraspanin CD81, suggesting that the protein plays a role in the regulation of late endosome membrane dynamics.
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Affiliation(s)
- Ben Brankatschk
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Véronique Pons
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Robert G. Parton
- Institute for Molecular Bioscience and Center for Microscopy and Microanalysis, University of Queensland, Brisbane, Australia
| | - Jean Gruenberg
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
- * E-mail:
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Laulagnier K, Schieber NL, Maritzen T, Haucke V, Parton RG, Gruenberg J. Role of AP1 and Gadkin in the traffic of secretory endo-lysosomes. Mol Biol Cell 2011; 22:2068-82. [PMID: 21525240 PMCID: PMC3113771 DOI: 10.1091/mbc.e11-03-0193] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 04/12/2011] [Accepted: 04/19/2011] [Indexed: 11/11/2022] Open
Abstract
Whereas lysosome-related organelles (LRO) of specialized cells display both exocytic and endocytic features, lysosomes in nonspecialized cells can also acquire the property to fuse with the plasma membrane upon an acute rise in cytosolic calcium. Here, we characterize this unconventional secretory pathway in fibroblast-like cells, by monitoring the appearance of Lamp1 on the plasma membrane and the release of lysosomal enzymes into the medium. After sequential ablation of endocytic compartments in living cells, we find that donor membranes primarily derive from a late compartment, but that an early compartment is also involved. Strikingly, this endo-secretory process is not affected by treatments that inhibit endosome dynamics (microtubule depolymerization, cholesterol accumulation, overexpression of Rab7 or its effector Rab-interacting lysosomal protein [RILP], overexpression of Rab5 mutants), but depends on Rab27a, a GTPase involved in LRO secretion, and is controlled by F-actin. Moreover, we find that this unconventional endo-secretory pathway requires the adaptor protein complexes AP1, Gadkin (which recruits AP1 by binding to the γ1 subunit), and AP2, but not AP3. We conclude that a specific fraction of the AP2-derived endocytic pathway is dedicated to secretory purposes under the control of AP1 and Gadkin.
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Affiliation(s)
- Karine Laulagnier
- Department of Biochemistry, University of Geneva, 1211-Geneva-4, Switzerland
| | - Nicole L. Schieber
- Institute for Molecular Bioscience and Center for Microscopy and Microanalysis, The University of Queensland, Brisbane 4072, Australia
| | - Tanja Maritzen
- Laboratory of Membrane Biochemistry, Freie Universitaet Berlin, 14195 Berlin, Germany
| | - Volker Haucke
- Laboratory of Membrane Biochemistry, Freie Universitaet Berlin, 14195 Berlin, Germany
| | - Robert G. Parton
- Institute for Molecular Bioscience and Center for Microscopy and Microanalysis, The University of Queensland, Brisbane 4072, Australia
| | - Jean Gruenberg
- Department of Biochemistry, University of Geneva, 1211-Geneva-4, Switzerland
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Microscopy. J Microbiol Methods 2011. [DOI: 10.1016/b978-0-12-387730-7.00004-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
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50
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Maderna P, Cottell DC, Toivonen T, Dufton N, Dalli J, Perretti M, Godson C. FPR2/ALX receptor expression and internalization are critical for lipoxin A4 and annexin-derived peptide-stimulated phagocytosis. FASEB J 2010; 24:4240-9. [PMID: 20570963 PMCID: PMC4338542 DOI: 10.1096/fj.10-159913] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Lipoxins (LXs) are endogenously produced eicosanoids with well-described anti-inflammatory and proresolution activities, stimulating nonphlogistic phagocytosis of apoptotic cells by macrophages. LXA(4) and the glucocorticoid-derived annexin A1 peptide (Ac2-26) bind to a common G-protein-coupled receptor, termed FPR2/ALX. However, direct evidence of the involvement of FPR2/ALX in the anti-inflammatory and proresolution activity of LXA(4) is still to be investigated. Here we describe FPR2/ALX trafficking in response to LXA(4) and Ac2-26 stimulation. We have transfected cells with HA-tagged FPR2/ALX and studied receptor trafficking in unstimulated, LXA(4) (1-10 nM)- and Ac2-26 (30 μM)-treated cells using multiple approaches that include immunofluorescent confocal microscopy, immunogold labeling of cryosections, and ELISA and investigated receptor trafficking in agonist-stimulated phagocytosis. We conclude that PKC-dependent internalization of FPR2/ALX is required for phagocytosis. Using bone marrow-derived macrophages (BMDMs) from mice in which the FPR2/ALX ortholog Fpr2 had been deleted, we observed the nonredundant function for this receptor in LXA(4) and Ac2-26 stimulated phagocytosis of apoptotic neutrophils. LXA(4) stimulated phagocytosis 1.7-fold above basal (P<0.001) by BMDMs from wild-type mice, whereas no effect was found on BMDMs from Fpr2(-/-) mice. Similarly, Ac2-26 stimulates phagocytosis by BMDMs from wild-type mice 1.5-fold above basal (P<0.05). However, Ac2-26 failed to stimulate phagocytosis by BMDMs isolated from Fpr2(-/-) mice relative to vehicle. These data reveal novel and complex mechanisms of the FPR2/ALX receptor trafficking and functionality in the resolution of inflammation.
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Affiliation(s)
- Paola Maderna
- UCD Diabetes Research Centre, UCD School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - David C. Cottell
- The Electron Microscopy Laboratory, UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Tiina Toivonen
- The Electron Microscopy Laboratory, UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Neil Dufton
- The William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, London, UK
| | - Jesmond Dalli
- The William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, London, UK
| | - Mauro Perretti
- The William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, London, UK
| | - Catherine Godson
- UCD Diabetes Research Centre, UCD School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
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