1
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Fermie J, de Jager L, Foster HE, Veenendaal T, de Heus C, van Dijk S, ten Brink C, Oorschot V, Yang L, Li W, Müller WH, Howes S, Carter AP, Förster F, Posthuma G, Gerritsen HC, Klumperman J, Liv N. Bimodal endocytic probe for three-dimensional correlative light and electron microscopy. CELL REPORTS METHODS 2022; 2:100220. [PMID: 35637912 PMCID: PMC9142762 DOI: 10.1016/j.crmeth.2022.100220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 02/04/2022] [Accepted: 04/26/2022] [Indexed: 12/03/2022]
Abstract
We present a bimodal endocytic tracer, fluorescent BSA-gold (fBSA-Au), as a fiducial marker for 2D and 3D correlative light and electron microscopy (CLEM) applications. fBSA-Au consists of colloidal gold (Au) particles stabilized with fluorescent BSA. The conjugate is efficiently endocytosed and distributed throughout the 3D endolysosomal network of cells and has an excellent visibility in both fluorescence microscopy (FM) and electron microscopy (EM). We demonstrate that fBSA-Au facilitates rapid registration in several 2D and 3D CLEM applications using Tokuyasu cryosections, resin-embedded material, and cryoelectron microscopy (cryo-EM). Endocytosed fBSA-Au benefits from a homogeneous 3D distribution throughout the endosomal system within the cell, does not obscure any cellular ultrastructure, and enables accurate (50-150 nm) correlation of fluorescence to EM data. The broad applicability and visibility in both modalities makes fBSA-Au an excellent endocytic fiducial marker for 2D and 3D (cryo)CLEM applications.
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Affiliation(s)
- Job Fermie
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
- Molecular Biophysics, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, the Netherlands
| | - Leanne de Jager
- Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, Utrecht, the Netherlands
| | - Helen E. Foster
- Medical Research Council Laboratory of Molecular Biology, Division of Structural Studies, Cambridge, UK
| | - Tineke Veenendaal
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Cecilia de Heus
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Suzanne van Dijk
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Corlinda ten Brink
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Viola Oorschot
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Lin Yang
- Institute of Genetics & Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Wei Li
- Institute of Genetics & Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Wally H. Müller
- Microbiology, Department of Biology, Utrecht University, Utrecht, the Netherlands
| | - Stuart Howes
- Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, Utrecht, the Netherlands
| | - Andrew P. Carter
- Medical Research Council Laboratory of Molecular Biology, Division of Structural Studies, Cambridge, UK
| | - Friedrich Förster
- Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, Utrecht, the Netherlands
| | - George Posthuma
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Hans C. Gerritsen
- Molecular Biophysics, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, the Netherlands
| | - Judith Klumperman
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Nalan Liv
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
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2
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Parlanti P, Cappello V. Microscopes, tools, probes, and protocols: A guide in the route of correlative microscopy for biomedical investigation. Micron 2021; 152:103182. [PMID: 34801960 DOI: 10.1016/j.micron.2021.103182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 11/12/2021] [Accepted: 11/14/2021] [Indexed: 12/11/2022]
Abstract
In the last decades, the advancements of microscopes technology, together with the development of new imaging approaches, are trying to address some biological questions that have been unresolved in the past: the need to combine in the same analysis temporal, functional and morphological information on the biological sample has become pressing. For this reason, the use of correlative microscopy, in which two or more imaging techniques are combined in the same analysis, is getting increasingly widespread. In fact, correlative microscopy can overcome limitations of a single imaging method, giving access to a larger amount of information from the same specimen. However, correlative microscopy can be challenging, and appropriate protocols for sample preparation and imaging methods must be selected. Here we review the state of the art of correlating electron microscopy with different imaging methods, focusing on sample preparation, tools, and labeling methods, with the aim to provide a comprehensive guide for those scientists who are approaching the field of correlative methods.
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Affiliation(s)
- Paola Parlanti
- Istituto Italiano di Tecnologia, Center for Materials Interfaces, Electron Crystallography, Viale Rinaldo Piaggio 34, I-56025, Pontedera (PI), Italy.
| | - Valentina Cappello
- Istituto Italiano di Tecnologia, Center for Materials Interfaces, Electron Crystallography, Viale Rinaldo Piaggio 34, I-56025, Pontedera (PI), Italy.
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3
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Bao X, Koorengevel MC, Groot Koerkamp MJA, Homavar A, Weijn A, Crielaard S, Renne MF, Lorent JH, Geerts WJC, Surma MA, Mari M, Holstege FCP, Klose C, de Kroon AIPM. Shortening of membrane lipid acyl chains compensates for phosphatidylcholine deficiency in choline-auxotroph yeast. EMBO J 2021; 40:e107966. [PMID: 34520050 PMCID: PMC8521299 DOI: 10.15252/embj.2021107966] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 07/28/2021] [Accepted: 07/30/2021] [Indexed: 12/21/2022] Open
Abstract
Phosphatidylcholine (PC) is an abundant membrane lipid component in most eukaryotes, including yeast, and has been assigned multiple functions in addition to acting as building block of the lipid bilayer. Here, by isolating S. cerevisiae suppressor mutants that exhibit robust growth in the absence of PC, we show that PC essentiality is subject to cellular evolvability in yeast. The requirement for PC is suppressed by monosomy of chromosome XV or by a point mutation in the ACC1 gene encoding acetyl-CoA carboxylase. Although these two genetic adaptations rewire lipid biosynthesis in different ways, both decrease Acc1 activity, thereby reducing average acyl chain length. Consistently, soraphen A, a specific inhibitor of Acc1, rescues a yeast mutant with deficient PC synthesis. In the aneuploid suppressor, feedback inhibition of Acc1 through acyl-CoA produced by fatty acid synthase (FAS) results from upregulation of lipid synthesis. The results show that budding yeast regulates acyl chain length by fine-tuning the activities of Acc1 and FAS and indicate that PC evolved by benefitting the maintenance of membrane fluidity.
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Affiliation(s)
- Xue Bao
- Membrane Biochemistry & BiophysicsBijvoet Center for Biomolecular Research and Institute of BiomembranesUtrecht UniversityUtrechtThe Netherlands
| | - Martijn C Koorengevel
- Membrane Biochemistry & BiophysicsBijvoet Center for Biomolecular Research and Institute of BiomembranesUtrecht UniversityUtrechtThe Netherlands
| | | | - Amir Homavar
- Membrane Biochemistry & BiophysicsBijvoet Center for Biomolecular Research and Institute of BiomembranesUtrecht UniversityUtrechtThe Netherlands
| | - Amrah Weijn
- Membrane Biochemistry & BiophysicsBijvoet Center for Biomolecular Research and Institute of BiomembranesUtrecht UniversityUtrechtThe Netherlands
| | - Stefan Crielaard
- Membrane Biochemistry & BiophysicsBijvoet Center for Biomolecular Research and Institute of BiomembranesUtrecht UniversityUtrechtThe Netherlands
| | - Mike F Renne
- Membrane Biochemistry & BiophysicsBijvoet Center for Biomolecular Research and Institute of BiomembranesUtrecht UniversityUtrechtThe Netherlands
| | - Joseph H Lorent
- Membrane Biochemistry & BiophysicsBijvoet Center for Biomolecular Research and Institute of BiomembranesUtrecht UniversityUtrechtThe Netherlands
| | - Willie JC Geerts
- Cryo‐Electron MicroscopyBijvoet Center for Biomolecular ResearchUtrecht UniversityUtrechtThe Netherlands
| | | | - Muriel Mari
- Department of Biomedical Sciences of Cells & SystemsUniversity Medical Center GroningenUniversity of GroningenGroningenThe Netherlands
| | | | | | - Anton I P M de Kroon
- Membrane Biochemistry & BiophysicsBijvoet Center for Biomolecular Research and Institute of BiomembranesUtrecht UniversityUtrechtThe Netherlands
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4
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ER-Mitochondria Contact Sites Reporters: Strengths and Weaknesses of the Available Approaches. Int J Mol Sci 2020; 21:ijms21218157. [PMID: 33142798 PMCID: PMC7663704 DOI: 10.3390/ijms21218157] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/28/2020] [Accepted: 10/30/2020] [Indexed: 12/12/2022] Open
Abstract
Organelle intercommunication represents a wide area of interest. Over the last few decades, increasing evidence has highlighted the importance of organelle contact sites in many biological processes including Ca2+ signaling, lipid biosynthesis, apoptosis, and autophagy but also their involvement in pathological conditions. ER–mitochondria tethering is one of the most investigated inter-organelle communications and it is differently modulated in response to several cellular conditions including, but not limited to, starvation, Endoplasmic Reticulum (ER) stress, and mitochondrial shape modifications. Despite many studies aiming to understand their functions and how they are perturbed under different conditions, approaches to assess organelle proximity are still limited. Indeed, better visualization and characterization of contact sites remain a fascinating challenge. The aim of this review is to summarize strengths and weaknesses of the available methods to detect and quantify contact sites, with a main focus on ER–mitochondria tethering.
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5
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Franke C, Repnik U, Segeletz S, Brouilly N, Kalaidzidis Y, Verbavatz JM, Zerial M. Correlative single-molecule localization microscopy and electron tomography reveals endosome nanoscale domains. Traffic 2020; 20:601-617. [PMID: 31206952 PMCID: PMC6771687 DOI: 10.1111/tra.12671] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 06/04/2019] [Accepted: 06/09/2019] [Indexed: 12/12/2022]
Abstract
Many cellular organelles, including endosomes, show compartmentalization into distinct functional domains, which, however, cannot be resolved by diffraction‐limited light microscopy. Single molecule localization microscopy (SMLM) offers nanoscale resolution but data interpretation is often inconclusive when the ultrastructural context is missing. Correlative light electron microscopy (CLEM) combining SMLM with electron microscopy (EM) enables correlation of functional subdomains of organelles in relation to their underlying ultrastructure at nanometer resolution. However, the specific demands for EM sample preparation and the requirements for fluorescent single‐molecule photo‐switching are opposed. Here, we developed a novel superCLEM workflow that combines triple‐color SMLM (dSTORM & PALM) and electron tomography using semi‐thin Tokuyasu thawed cryosections. We applied the superCLEM approach to directly visualize nanoscale compartmentalization of endosomes in HeLa cells. Internalized, fluorescently labeled Transferrin and EGF were resolved into morphologically distinct domains within the same endosome. We found that the small GTPase Rab5 is organized in nanodomains on the globular part of early endosomes. The simultaneous visualization of several proteins in functionally distinct endosomal sub‐compartments demonstrates the potential of superCLEM to link the ultrastructure of organelles with their molecular organization at nanoscale resolution.
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Affiliation(s)
- Christian Franke
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Urska Repnik
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Sandra Segeletz
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Nicolas Brouilly
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Instutut de Biologie du Developpement de Marseille-Luminy, Aix-Marseille Universite, Marseille, France
| | - Yannis Kalaidzidis
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Faculty of Bioengineering and Bioinformatics, Moscow State University, Moscow, Russia
| | - Jean-Marc Verbavatz
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Institut Jacques Monod, CNRS, Université Paris-Diderot, Paris, France
| | - Marino Zerial
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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6
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Scorrano L, De Matteis MA, Emr S, Giordano F, Hajnóczky G, Kornmann B, Lackner LL, Levine TP, Pellegrini L, Reinisch K, Rizzuto R, Simmen T, Stenmark H, Ungermann C, Schuldiner M. Coming together to define membrane contact sites. Nat Commun 2019; 10:1287. [PMID: 30894536 PMCID: PMC6427007 DOI: 10.1038/s41467-019-09253-3] [Citation(s) in RCA: 369] [Impact Index Per Article: 73.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 02/21/2019] [Indexed: 12/14/2022] Open
Abstract
Close proximities between organelles have been described for decades. However, only recently a specific field dealing with organelle communication at membrane contact sites has gained wide acceptance, attracting scientists from multiple areas of cell biology. The diversity of approaches warrants a unified vocabulary for the field. Such definitions would facilitate laying the foundations of this field, streamlining communication and resolving semantic controversies. This opinion, written by a panel of experts in the field, aims to provide this burgeoning area with guidelines for the experimental definition and analysis of contact sites. It also includes suggestions on how to operationally and tractably measure and analyze them with the hope of ultimately facilitating knowledge production and dissemination within and outside the field of contact-site research.
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Affiliation(s)
- Luca Scorrano
- Venetian Institute of Molecular Medicine, Department of Biology, University of Padua, Padua, Italy.
| | - Maria Antonietta De Matteis
- Telethon Institute of Genetics and Medicine, Pozzuoli, Naples, Italy
- Department of Molecular Medicine and Medical Biotechnology, University of Napoli Federico II, Naples, Italy
| | - Scott Emr
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Francesca Giordano
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Paris-Sud University, Paris-Saclay University, Gif-sur-Yvette cedex, 91198, France.
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Benoît Kornmann
- University of Oxford, Department of Biochemistry, South Parks Road, Ox1 3QU, Oxford, United Kingdom
| | - Laura L Lackner
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, 60208, USA
| | - Tim P Levine
- UCL Institute of Ophthalmology, London, EC1V 9EL, UK
| | - Luca Pellegrini
- Department of Molecular Biology, Medical Biochemistry, and Pathology, Universitè Laval, Quebec, QC, Canada
| | - Karin Reinisch
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Thomas Simmen
- University of Alberta, Faculty of Medicine and Dentistry, Department of Cell Biology, Edmonton, AB, T6G2H7, Canada
| | - Harald Stenmark
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Montebello, N-0379, Oslo, Norway
| | - Christian Ungermann
- Department of Biology/Chemistry, University of Osnabrück, 49082, Osnabrück, Germany
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel.
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7
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Han S, Raabe M, Hodgson L, Mantell J, Verkade P, Lasser T, Landfester K, Weil T, Lieberwirth I. High-Contrast Imaging of Nanodiamonds in Cells by Energy Filtered and Correlative Light-Electron Microscopy: Toward a Quantitative Nanoparticle-Cell Analysis. NANO LETTERS 2019; 19:2178-2185. [PMID: 30810045 PMCID: PMC6437650 DOI: 10.1021/acs.nanolett.9b00752] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Fluorescent nanodiamonds (fNDs) represent an emerging class of nanomaterials offering great opportunities for ultrahigh resolution imaging, sensing and drug delivery applications. Their biocompatibility, exceptional chemical and consistent photostability renders them particularly attractive for correlative light-electron microscopy studies providing unique insights into nanoparticle-cell interactions. Herein, we demonstrate a stringent procedure to image and quantify fNDs with a high contrast down to the single particle level in cells. Individual fNDs were directly visualized by energy-filtered transmission electron microscopy, that is, inside newly forming, early endosomal vesicles during their cellular uptake processes as well as inside cellular organelles such as a mitochondrion. Furthermore, we demonstrate the unequivocal identification, localization, and quantification of individual fNDs in larger fND clusters inside intracellular vesicles. Our studies are of great relevance to obtain quantitative information on nanoparticle trafficking and their various interactions with cells, membranes, and organelles, which will be crucial to design-improved sensors, imaging probes, and nanotherapeutics based on quantitative data.
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Affiliation(s)
- Shen Han
- Max-Planck Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Marco Raabe
- Max-Planck Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Institute of Inorganic
Chemistry I, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Lorna Hodgson
- School of Biochemistry, University of Bristol, Medical Sciences Building, University
Walk, BS8 1TD Bristol, United Kingdom
| | - Judith Mantell
- School of Biochemistry, University of Bristol, Medical Sciences Building, University
Walk, BS8 1TD Bristol, United Kingdom
| | - Paul Verkade
- School of Biochemistry, University of Bristol, Medical Sciences Building, University
Walk, BS8 1TD Bristol, United Kingdom
| | - Theo Lasser
- Max-Planck Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Laboratoire d’Optique Biomédical, École Polytechnique Fédérale
de Lausanne, CH-1015 Lausanne, Switzerland
| | - Katharina Landfester
- Max-Planck Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Tanja Weil
- Max-Planck Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Institute of Inorganic
Chemistry I, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
- E-mail:
(T.W.)
| | - Ingo Lieberwirth
- Max-Planck Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- E-mail: (I.L.)
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8
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Gómez-Sánchez R, Rose J, Guimarães R, Mari M, Papinski D, Rieter E, Geerts WJ, Hardenberg R, Kraft C, Ungermann C, Reggiori F. Atg9 establishes Atg2-dependent contact sites between the endoplasmic reticulum and phagophores. J Cell Biol 2018; 217:2743-2763. [PMID: 29848619 PMCID: PMC6080931 DOI: 10.1083/jcb.201710116] [Citation(s) in RCA: 165] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 03/07/2018] [Accepted: 05/02/2018] [Indexed: 11/22/2022] Open
Abstract
The autophagy-related (Atg) proteins play a key role in the formation of autophagosomes, the hallmark of autophagy. The function of the cluster composed by Atg2, Atg18, and transmembrane Atg9 is completely unknown despite their importance in autophagy. In this study, we provide insights into the molecular role of these proteins by identifying and characterizing Atg2 point mutants impaired in Atg9 binding. We show that Atg2 associates to autophagosomal membranes through lipid binding and independently from Atg9. Its interaction with Atg9, however, is key for Atg2 confinement to the growing phagophore extremities and subsequent association of Atg18. Assembly of the Atg9-Atg2-Atg18 complex is important to establish phagophore-endoplasmic reticulum (ER) contact sites. In turn, disruption of the Atg2-Atg9 interaction leads to an aberrant topological distribution of both Atg2 and ER contact sites on forming phagophores, which severely impairs autophagy. Altogether, our data shed light in the interrelationship between Atg9, Atg2, and Atg18 and highlight the possible functional relevance of the phagophore-ER contact sites in phagophore expansion.
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Affiliation(s)
- Rubén Gómez-Sánchez
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Jaqueline Rose
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Rodrigo Guimarães
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
- Department of Cell Biology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Muriel Mari
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Daniel Papinski
- Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Ester Rieter
- Department of Cell Biology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Willie J Geerts
- Biomolecular Imaging, Bijvoet Center, Utrecht University, Utrecht, Netherlands
| | - Ralph Hardenberg
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Claudine Kraft
- Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
- Institute of Biochemistry and Molecular Biology, Institute of Molecular Medicine and Cell Research, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Fulvio Reggiori
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
- Department of Cell Biology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
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9
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Harner ME, Unger AK, Geerts WJ, Mari M, Izawa T, Stenger M, Geimer S, Reggiori F, Westermann B, Neupert W. An evidence based hypothesis on the existence of two pathways of mitochondrial crista formation. eLife 2016; 5. [PMID: 27849155 PMCID: PMC5138035 DOI: 10.7554/elife.18853] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 11/14/2016] [Indexed: 12/31/2022] Open
Abstract
Metabolic function and architecture of mitochondria are intimately linked. More than 60 years ago, cristae were discovered as characteristic elements of mitochondria that harbor the protein complexes of oxidative phosphorylation, but how cristae are formed, remained an open question. Here we present experimental results obtained with yeast that support a novel hypothesis on the existence of two molecular pathways that lead to the generation of lamellar and tubular cristae. Formation of lamellar cristae depends on the mitochondrial fusion machinery through a pathway that is required also for homeostasis of mitochondria and mitochondrial DNA. Tubular cristae are formed via invaginations of the inner boundary membrane by a pathway independent of the fusion machinery. Dimerization of the F1FO-ATP synthase and the presence of the MICOS complex are necessary for both pathways. The proposed hypothesis is suggested to apply also to higher eukaryotes, since the key components are conserved in structure and function throughout evolution. DOI:http://dx.doi.org/10.7554/eLife.18853.001 Cells contain compartments called mitochondria, which are often called the powerhouses of the cell because they provide energy that drives vital cellular processes. Mitochondria have two membranes: an outer and an inner membrane. The outer membrane separates the mitochondria from the rest of the cell. The inner membrane is elaborately folded and the folds – called cristae – create a larger space to accommodate all of the protein machinery involved in producing energy. The cristae can be shaped as flat sac-like structures called lamellar cristae or as tubes known as tubular cristae. Mitochondria are dynamic and are constantly fusing with other mitochondria and splitting up. Even though the internal architecture of mitochondria was first revealed around 60 years ago, it is still not clear how the cristae form. Harner et al. now address this question in yeast cells by combining imaging, biochemistry and genetic approaches. The experiments show that lamellar cristae form when two mitochondria fuse with each other. The outer membranes merge and then the inner membranes start to fuse around their edges to generate the sac-like structure of lamellar cristae. A yeast protein called Mgm1 (known as Opa1 in mammals) drives the fusion of the inner membranes, but this process only takes place when enzymes called F1FO-ATP synthases on the inner membrane form pairs with one another. These F1FO-ATP synthase pairs stabilize the cristae membranes as they curve to form the sac-like structure. Later on, the formation of a group of proteins called the MICOS complex halts the fusion process to prevent the lamellar cristae from completely separating from the rest of the inner membrane. Harner et al. also found that tubular cristae form using a different mechanism when the inner membrane of the mitochondria grows inwards. This process also requires pairs of F1FO-ATP synthases and the MICOS complex, but does not involve Mgm1/Opa1. Together, these findings show that lamellar and tubular cristae in yeast form using two different mechanisms. Since the key components of these mechanisms are also found in virtually all other eukaryotes, the findings of Harner et al. are also likely to apply to many other organisms including animals. DOI:http://dx.doi.org/10.7554/eLife.18853.002
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Affiliation(s)
- Max E Harner
- Max Planck Institute of Biochemistry, Martinsried, Germany.,Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Ann-Katrin Unger
- Cell Biology and Electron Microscopy, Universität Bayreuth, Bayreuth, Germany
| | - Willie Jc Geerts
- Biomolecular Imaging, Bijvoet Center, Universiteit Utrecht, Utrecht, Netherlands
| | - Muriel Mari
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Toshiaki Izawa
- Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Maria Stenger
- Cell Biology and Electron Microscopy, Universität Bayreuth, Bayreuth, Germany
| | - Stefan Geimer
- Cell Biology and Electron Microscopy, Universität Bayreuth, Bayreuth, Germany
| | - Fulvio Reggiori
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Benedikt Westermann
- Cell Biology and Electron Microscopy, Universität Bayreuth, Bayreuth, Germany
| | - Walter Neupert
- Max Planck Institute of Biochemistry, Martinsried, Germany.,Department of Anatomy and Cell Biology, Biomedical Center, Ludwig-Maximilians Universität München, Martinsried, Germany
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10
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Three-dimensional and immune electron microscopic analysis of the secretory pathway in Saccharomyces cerevisiae. Histochem Cell Biol 2016; 146:515-527. [DOI: 10.1007/s00418-016-1483-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2016] [Indexed: 01/07/2023]
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Papanikou E, Day KJ, Austin J, Glick BS. COPI selectively drives maturation of the early Golgi. eLife 2015; 4. [PMID: 26709839 PMCID: PMC4758959 DOI: 10.7554/elife.13232] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 12/27/2015] [Indexed: 12/12/2022] Open
Abstract
COPI coated vesicles carry material between Golgi compartments, but the role of COPI in the secretory pathway has been ambiguous. Previous studies of thermosensitive yeast COPI mutants yielded the surprising conclusion that COPI was dispensable both for the secretion of certain proteins and for Golgi cisternal maturation. To revisit these issues, we optimized the anchor-away method, which allows peripheral membrane proteins such as COPI to be sequestered rapidly by adding rapamycin. Video fluorescence microscopy revealed that COPI inactivation causes an early Golgi protein to remain in place while late Golgi proteins undergo cycles of arrival and departure. These dynamics generate partially functional hybrid Golgi structures that contain both early and late Golgi proteins, explaining how secretion can persist when COPI has been inactivated. Our findings suggest that cisternal maturation involves a COPI-dependent pathway that recycles early Golgi proteins, followed by multiple COPI-independent pathways that recycle late Golgi proteins. DOI:http://dx.doi.org/10.7554/eLife.13232.001 Proteins play many important roles for cells, and these roles often require the proteins to be in particular locations in or around the cells. A set of cell compartments called the Golgi packages certain proteins into bubble-like structures called vesicles to enable the proteins to be used elsewhere in the cell or released to the outside of the cell, in a process called the secretory pathway. The operation of the secretory pathway requires the Golgi compartments to be continually remodeled. Proteins and other materials can be ferried between the compartments of the Golgi by another type of vesicle. These vesicles are coated with a group, or complex, of proteins called COPI, which forms a curved lattice around the vesicles and helps them to capture the materials they will transport. However, it is not clear whether COPI is also involved in remodeling of the Golgi compartments. Papanikou, Day et al. addressed this question using a technique called the “anchor-away method” combined with microscopy to study COPI in yeast cells. The yeast were genetically engineered so that COPI activity was effectively shut down in the presence of a drug called rapamycin. The experiments show that COPI is involved in the early stages of remodeling the Golgi compartments, but not the later stages. This finding supports the emerging view of the Golgi as a self-organizing cellular machine, and it provides a framework for uncovering the engineering principles that underlie the secretory pathway. DOI:http://dx.doi.org/10.7554/eLife.13232.002
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Affiliation(s)
- Effrosyni Papanikou
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, United States
| | - Kasey J Day
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, United States
| | - Jotham Austin
- Electron Microscopy Core Facility, The University of Chicago, Chicago, United States
| | - Benjamin S Glick
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, United States
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Frankl A, Mari M, Reggiori F. Electron microscopy for ultrastructural analysis and protein localization in Saccharomyces cerevisiae. MICROBIAL CELL 2015; 2:412-428. [PMID: 28357267 PMCID: PMC5349205 DOI: 10.15698/mic2015.11.237] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The yeast Saccharomyces cerevisiae is a key model system for studying of a multitude of cellular processes because of its amenability to genetics, molecular biology and biochemical procedures. Ultrastructural examinations of this organism, though, are traditionally difficult because of the presence of a thick cell wall and the high density of cytoplasmic proteins. A series of recent methodological and technical developments, however, has revived interest in morphological analyses of yeast (e.g. 123). Here we present a review of established and new methods, from sample preparation to imaging, for the ultrastructural analysis of S. cerevisiae. We include information for the use of different fixation methods, embedding procedures, approaches for contrast enhancement, and sample visualization techniques, with references to successful examples. The goal of this review is to guide researchers that want to investigate a particular process at the ultrastructural level in yeast by aiding in the selection of the most appropriate approach to visualize a specific structure or subcellular compartment.
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Affiliation(s)
- Andri Frankl
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Muriel Mari
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Fulvio Reggiori
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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Biazik J, Vihinen H, Anwar T, Jokitalo E, Eskelinen EL. The versatile electron microscope: An ultrastructural overview of autophagy. Methods 2015; 75:44-53. [DOI: 10.1016/j.ymeth.2014.11.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 11/19/2014] [Accepted: 11/20/2014] [Indexed: 01/08/2023] Open
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