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Brunner M, Lopez-Rodriguez D, Estrada-Meza J, Dali R, Rohrbach A, Deglise T, Messina A, Thorens B, Santoni F, Langlet F. Fasting induces metabolic switches and spatial redistributions of lipid processing and neuronal interactions in tanycytes. Nat Commun 2024; 15:6604. [PMID: 39098920 DOI: 10.1038/s41467-024-50913-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 07/25/2024] [Indexed: 08/06/2024] Open
Abstract
The ependyma lining the third ventricle (3V) in the mediobasal hypothalamus plays a crucial role in energy balance and glucose homeostasis. It is characterized by a high functional heterogeneity and plasticity, but the underlying molecular mechanisms governing its features are not fully understood. Here, 5481 hypothalamic ependymocytes were cataloged using FACS-assisted scRNAseq from fed, 12h-fasted, and 24h-fasted adult male mice. With standard clustering analysis, typical ependymal cells and β2-tanycytes appear sharply defined, but other subpopulations, β1- and α-tanycytes, display fuzzy boundaries with few or no specific markers. Pseudospatial approaches, based on the 3V neuroanatomical distribution, enable the identification of specific versus shared tanycyte markers and subgroup-specific versus general tanycyte functions. We show that fasting dynamically shifts gene expression patterns along the 3V, leading to a spatial redistribution of cell type-specific responses. Altogether, we show that changes in energy status induce metabolic and functional switches in tanycyte subpopulations, providing insights into molecular and functional diversity and plasticity within the tanycyte population.
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Affiliation(s)
- Maxime Brunner
- Service of Endocrinology, Diabetology, and Metabolism, Lausanne University Hospital, Lausanne, Switzerland
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - David Lopez-Rodriguez
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Judith Estrada-Meza
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Rafik Dali
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Antoine Rohrbach
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Tamara Deglise
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Andrea Messina
- Service of Endocrinology, Diabetology, and Metabolism, Lausanne University Hospital, Lausanne, Switzerland
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Bernard Thorens
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Federico Santoni
- Service of Endocrinology, Diabetology, and Metabolism, Lausanne University Hospital, Lausanne, Switzerland.
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
- Institute for Genetic and Biomedical Research (IRGB) - CNR, Monserrato, Italy.
| | - Fanny Langlet
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
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2
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Kolotuev I. Work smart, not hard: How array tomography can help increase the ultrastructure data output. J Microsc 2024; 295:42-60. [PMID: 37626455 DOI: 10.1111/jmi.13217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Revised: 08/16/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023]
Abstract
Transmission electron microscopy has been essential for understanding cell biology for over six decades. Volume electron microscopy tools, such as serial block face and focused ion beam scanning electron microscopy acquisition, brought a new era to ultrastructure analysis. 'Array Tomography' (AT) refers to sequential image acquisition of resin-embedded sample sections on a large support (coverslip, glass slide, silicon wafers) for immunolabelling with multiple fluorescent labels, occasionally combined with ultrastructure observation. Subsequently, the term was applied to generating and imaging a series of sections to acquire a 3D representation of a structure using scanning electron microscopy (SEM). Although this is a valuable application, the potential of AT is to facilitate many tasks that are difficult or even impossible to obtain by Transmission Electron Microscopy (TEM). Due to the straightforward nature and versatility of AT sample preparation and image acquisition, the technique can be applied practically to any biological sample for selected sections or volume electron microscopy analysis. Furthermore, in addition to the benefits described here, AT is compatible with morphological analysis, multiplex immunolabelling, immune-gold labelling, and correlative light and electron microscopy workflow applicable for single cells, tissue and small organisms. This versatility makes AT attractive not only for basic research but as a diagnostic tool with a simplified routine.
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Affiliation(s)
- Irina Kolotuev
- Electron Microscopy Facility, University of Lausanne, Lausanne, Switzerland
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3
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Esmangart de Bournonville T, Jaglarz MK, Durel E, Le Borgne R. ESCRT-III-dependent adhesive and mechanical changes are triggered by a mechanism detecting alteration of septate junction integrity in Drosophila epithelial cells. eLife 2024; 13:e91246. [PMID: 38305711 PMCID: PMC10959524 DOI: 10.7554/elife.91246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 02/01/2024] [Indexed: 02/03/2024] Open
Abstract
Barrier functions of proliferative epithelia are constantly challenged by mechanical and chemical constraints. How epithelia respond to and cope with disturbances of barrier functions to allow tissue integrity maintenance is poorly characterised. Cellular junctions play an important role in this process and intracellular traffic contribute to their homeostasis. Here, we reveal that, in Drosophila pupal notum, alteration of the bi- or tricellular septate junctions (SJs) triggers a mechanism with two prominent outcomes. On one hand, there is an increase in the levels of E-cadherin, F-actin, and non-muscle myosin II in the plane of adherens junctions. On the other hand, β-integrin/Vinculin-positive cell contacts are reinforced along the lateral and basal membranes. We found that the weakening of SJ integrity, caused by the depletion of bi- or tricellular SJ components, alters ESCRT-III/Vps32/Shrub distribution, reduces degradation and instead favours recycling of SJ components, an effect that extends to other recycled transmembrane protein cargoes including Crumbs, its effector β-Heavy Spectrin Karst, and β-integrin. We propose a mechanism by which epithelial cells, upon sensing alterations of the SJ, reroute the function of Shrub to adjust the balance of degradation/recycling of junctional cargoes and thereby compensate for barrier junction defects to maintain epithelial integrity.
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Affiliation(s)
- Thomas Esmangart de Bournonville
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) – UMR 6290RennesFrance
- Global Health Institute, School of Life Science, Ecole Polytechnique Fédérale de Lausanne (EPFL)LausanneSwitzerland
| | - Mariusz K Jaglarz
- Department of Developmental Biology and Invertebrate Morphology, Institute of Zoology and Biomedical Research, Jagiellonian University in KrakowKrakowPoland
| | - Emeline Durel
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) – UMR 6290RennesFrance
| | - Roland Le Borgne
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) – UMR 6290RennesFrance
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4
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Vérièpe-Salerno J, Podavini S, Long MJ, Kolotuev I, Cuendet M, Thome M. MALT-1 shortens lifespan by inhibiting autophagy in the intestine of C. elegans. AUTOPHAGY REPORTS 2023; 2:2277584. [PMID: 38510643 PMCID: PMC7615756 DOI: 10.1080/27694127.2023.2277584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 10/21/2023] [Indexed: 03/22/2024]
Abstract
The caspase-like protease MALT1 promotes immune responses and oncogenesis in mammals by activating the transcription factor NF-κB. MALT1 is remarkably conserved from mammals to simple metazoans devoid of NF-κB homologs, like the nematode C. elegans. To discover more ancient, NF-κB -independent MALT1 functions, we analysed the phenotype of C. elegans upon silencing of MALT-1 expression systemically or in a tissue-specific manner. MALT-1 silencing in the intestine caused a significant increase in life span, whereas intestinal overexpression of MALT-1 shortened life expectancy. Interestingly, MALT-1-deficient animals showed higher constitutive levels of autophagy in the intestine, which were particularly evident in aged or starved nematodes. Silencing of the autophagy regulators ATG-13, BEC-1 or LGG-2, but not the TOR homolog LET-363, reversed lifespan extension caused by MALT-1 deficiency. These findings suggest that MALT-1 limits the lifespan of C. elegans by acting as an inhibitor of an early step of autophagy in the intestine.
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Affiliation(s)
- Julie Vérièpe-Salerno
- Department of Immunobiology, Faculty of Biology and Medicine, University of Lausanne, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
| | - Silvia Podavini
- Department of Immunobiology, Faculty of Biology and Medicine, University of Lausanne, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
| | - Marcus J.C. Long
- Department of Immunobiology, Faculty of Biology and Medicine, University of Lausanne, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
| | - Irina Kolotuev
- Electron Microscopy Facility, University of Lausanne, Quartier Sorge – Biophore, CH-1015 Lausanne, Switzerland
| | - Muriel Cuendet
- School of Pharmaceutical Sciences, University of Geneva, Rue Michel-Servet 1, CH-1211 Geneva, Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, Rue Michel-Servet 1, CH-1211 Geneva, Switzerland
| | - Margot Thome
- Department of Immunobiology, Faculty of Biology and Medicine, University of Lausanne, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
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5
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Fung W, Tan TM, Kolotuev I, Heiman MG. A sex-specific switch in a single glial cell patterns the apical extracellular matrix. Curr Biol 2023; 33:4174-4186.e7. [PMID: 37708887 PMCID: PMC10578079 DOI: 10.1016/j.cub.2023.08.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 07/17/2023] [Accepted: 08/16/2023] [Indexed: 09/16/2023]
Abstract
Apical extracellular matrix (aECM) constitutes the interface between every tissue and the outside world. It is patterned into diverse tissue-specific structures through unknown mechanisms. Here, we show that a male-specific genetic switch in a single C. elegans glial cell patterns the overlying aECM from a solid sheet to an ∼200 nm pore, thus allowing a male sensory neuron to access the environment. Using cell-specific genetic sex reversal, we find that this switch reflects an inherent sex difference in the glial cell that is independent of the sex identity of the surrounding neurons. Through candidate and unbiased genetic screens, we find that this glial sex difference is controlled by factors shared with neurons (mab-3, lep-2, and lep-5) as well as previously unidentified regulators whose effects may be glia specific (nfya-1, bed-3, and jmjd-3.1). The switch results in male-specific glial expression of a secreted Hedgehog-related protein, GRL-18, that we discover localizes to transient nanoscale rings at sites where aECM pores will form. Using electron microscopy, we find that blocking male-specific gene expression in glia prevents pore formation, whereas forcing male-specific glial gene expression induces an ectopic pore. Thus, a switch in gene expression in a single cell is necessary and sufficient to pattern aECM into a specific structure. Our results highlight that aECM is not a simple homogeneous meshwork, but instead is composed of discrete local features that reflect the identity of the underlying cells.
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Affiliation(s)
- Wendy Fung
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA
| | - Taralyn M Tan
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA
| | - Irina Kolotuev
- Electron Microscopy Facility, University of Lausanne, 1015 Lausanne, Switzerland
| | - Maxwell G Heiman
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA.
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6
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Galenza A, Moreno-Roman P, Su YH, Acosta-Alvarez L, Debec A, Guichet A, Knapp JM, Kizilyaprak C, Humbel BM, Kolotuev I, O'Brien LE. Basal stem cell progeny establish their apical surface in a junctional niche during turnover of an adult barrier epithelium. Nat Cell Biol 2023; 25:658-671. [PMID: 36997641 PMCID: PMC10317055 DOI: 10.1038/s41556-023-01116-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 02/23/2023] [Indexed: 04/01/2023]
Abstract
Barrier epithelial organs face the constant challenge of sealing the interior body from the external environment while simultaneously replacing the cells that contact this environment. New replacement cells-the progeny of basal stem cells-are born without barrier-forming structures such as a specialized apical membrane and occluding junctions. Here, we investigate how new progeny acquire barrier structures as they integrate into the intestinal epithelium of adult Drosophila. We find they gestate their future apical membrane in a sublumenal niche created by a transitional occluding junction that envelops the differentiating cell and enables it to form a deep, microvilli-lined apical pit. The transitional junction seals the pit from the intestinal lumen until differentiation-driven, basal-to-apical remodelling of the niche opens the pit and integrates the now-mature cell into the barrier. By coordinating junctional remodelling with terminal differentiation, stem cell progeny integrate into a functional, adult epithelium without jeopardizing barrier integrity.
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Affiliation(s)
- Anthony Galenza
- Department of Molecular & Cellular Physiology and Institute of Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Paola Moreno-Roman
- Department of Molecular & Cellular Physiology and Institute of Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
- Foldscope Instruments, Inc., Palo Alto, CA, USA
| | - Yu-Han Su
- Department of Molecular & Cellular Physiology and Institute of Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Lehi Acosta-Alvarez
- Department of Molecular & Cellular Physiology and Institute of Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Alain Debec
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
- Institute of Ecology and Environmental Sciences, iEES, Sorbonne University, UPEC, CNRS, IRD, INRA, Paris, France
| | - Antoine Guichet
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | | | - Caroline Kizilyaprak
- Université de Lausanne, Bâtiment Biophore, Quartier Sorge, Lausanne, Switzerland
| | - Bruno M Humbel
- Université de Lausanne, Bâtiment Biophore, Quartier Sorge, Lausanne, Switzerland
- Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Tokyo, Japan
- Provost's Office, Okinawa Institute of Science and Technology, Tancha, Japan
| | - Irina Kolotuev
- Université de Lausanne, Bâtiment Biophore, Quartier Sorge, Lausanne, Switzerland
| | - Lucy Erin O'Brien
- Department of Molecular & Cellular Physiology and Institute of Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA.
- Chan-Zuckerberg Biohub, San Francisco, CA, USA.
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7
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Xuan Z, Yang S, Clark B, Hill SE, Manning L, Colón-Ramos DA. The active zone protein Clarinet regulates synaptic sorting of ATG-9 and presynaptic autophagy. PLoS Biol 2023; 21:e3002030. [PMID: 37053235 PMCID: PMC10101500 DOI: 10.1371/journal.pbio.3002030] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 02/08/2023] [Indexed: 04/14/2023] Open
Abstract
Autophagy is essential for cellular homeostasis and function. In neurons, autophagosome biogenesis is temporally and spatially regulated to occur near presynaptic sites, in part via the trafficking of autophagy transmembrane protein ATG-9. The molecules that regulate autophagy by sorting ATG-9 at synapses remain largely unknown. Here, we conduct forward genetic screens at single synapses of C. elegans neurons and identify a role for the long isoform of the active zone protein Clarinet (CLA-1L) in regulating sorting of autophagy protein ATG-9 at synapses, and presynaptic autophagy. We determine that disrupting CLA-1L results in abnormal accumulation of ATG-9 containing vesicles enriched with clathrin. The ATG-9 phenotype in cla-1(L) mutants is not observed for other synaptic vesicle proteins, suggesting distinct mechanisms that regulate sorting of ATG-9-containing vesicles and synaptic vesicles. Through genetic analyses, we uncover the adaptor protein complexes that genetically interact with CLA-1 in ATG-9 sorting. We also determine that CLA-1L extends from the active zone to the periactive zone and genetically interacts with periactive zone proteins in ATG-9 sorting. Our findings reveal novel roles for active zone proteins in the sorting of ATG-9 and in presynaptic autophagy.
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Affiliation(s)
- Zhao Xuan
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and Cell Biology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Sisi Yang
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and Cell Biology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Benjamin Clark
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and Cell Biology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Sarah E. Hill
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and Cell Biology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Laura Manning
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and Cell Biology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Daniel A. Colón-Ramos
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and Cell Biology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Instituto de Neurobiología, Recinto de Ciencias Médicas, Universidad de Puerto Rico, San Juan,Puerto Rico
- Wu Tsai Institute, Yale University, New Haven, Connecticut, United States of America
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8
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Fung W, Tan TM, Kolotuev I, Heiman MG. A sex-specific switch in a single glial cell patterns the apical extracellular matrix. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.17.533199. [PMID: 36993293 PMCID: PMC10055199 DOI: 10.1101/2023.03.17.533199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Apical extracellular matrix (aECM) constitutes the interface between every tissue and the outside world. It is patterned into diverse tissue-specific structures through unknown mechanisms. Here, we show that a male-specific genetic switch in a single C. elegans glial cell patterns the aECM into a ∼200 nm pore, allowing a male sensory neuron to access the environment. We find that this glial sex difference is controlled by factors shared with neurons ( mab-3, lep-2, lep-5 ) as well as previously unidentified regulators whose effects may be glia-specific ( nfya-1, bed-3, jmjd-3.1 ). The switch results in male-specific expression of a Hedgehog-related protein, GRL-18, that we discover localizes to transient nanoscale rings at sites of aECM pore formation. Blocking male-specific gene expression in glia prevents pore formation, whereas forcing male-specific expression induces an ectopic pore. Thus, a switch in gene expression in a single cell is necessary and sufficient to pattern aECM into a specific structure.
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Affiliation(s)
- Wendy Fung
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children’s Hospital, Boston, MA 02115, USA
| | - Taralyn M. Tan
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children’s Hospital, Boston, MA 02115, USA
| | - Irina Kolotuev
- Electron Microscopy Facility, University of Lausanne, 1015 Lausanne, Switzerland
| | - Maxwell G. Heiman
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children’s Hospital, Boston, MA 02115, USA
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9
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Ktena N, Kaplanis SI, Kolotuev I, Georgilis A, Kallergi E, Stavroulaki V, Nikoletopoulou V, Savvaki M, Karagogeos D. Autophagic degradation of CNS myelin maintains axon integrity. Cell Stress 2022; 6:93-107. [PMID: 36478958 PMCID: PMC9707329 DOI: 10.15698/cst2022.12.274] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 11/01/2022] [Accepted: 11/09/2022] [Indexed: 09/05/2023] Open
Abstract
(Macro)autophagy is a major lysosome-dependent degradation mechanism which engulfs, removes and recycles unwanted cytoplasmic material, including damaged organelles and toxic protein aggregates. Although a few studies implicate autophagy in CNS demyelinating pathologies, its role, particularly in mature oligodendrocytes and CNS myelin, remains poorly studied. Here, using both pharmacological and genetic inhibition of the autophagic machinery, we provide evidence that autophagy is an essential mechanism for oligodendrocyte maturation in vitro. Our study reveals that two core myelin proteins, namely proteolipid protein (PLP) and myelin basic protein (MBP) are incorporated into autophagosomes in oligodendrocytes, resulting in their degradation. Furthermore, we ablated atg5, a core gene of the autophagic machinery, specifically in myelinating glial cells in vivo by tamoxifen administration (plp-Cre ERT2 ; atg5 f/f ) and showed that myelin maintenance is perturbed, leading to PLP accumulation. Significant morphological defects in myelin membrane such as decompaction accompanied with increased axonal degeneration are observed. As a result, the mice exhibit behavioral deficits. In summary, our data highlight that the maintenance of adult myelin homeostasis in the CNS requires the involvement of a fully functional autophagic machinery.
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Affiliation(s)
- Niki Ktena
- School of Medicine, University of Crete, Heraklion, Greece
- Institute of Molecular Biology and Biotechnology, FORTH, Heraklion, Greece
| | - Stefanos Ioannis Kaplanis
- School of Medicine, University of Crete, Heraklion, Greece
- Institute of Molecular Biology and Biotechnology, FORTH, Heraklion, Greece
| | - Irina Kolotuev
- Electron Microscopy Facility (PME), University of Lausanne, Lausanne, Switzerland
| | | | - Emmanouela Kallergi
- Department of Fundamental Neurosciences (DNF), University of Lausanne, Lausanne, Switzerland
| | - Vasiliki Stavroulaki
- School of Medicine, University of Crete, Heraklion, Greece
- Institute of Molecular Biology and Biotechnology, FORTH, Heraklion, Greece
| | | | - Maria Savvaki
- School of Medicine, University of Crete, Heraklion, Greece
- Institute of Molecular Biology and Biotechnology, FORTH, Heraklion, Greece
| | - Domna Karagogeos
- School of Medicine, University of Crete, Heraklion, Greece
- Institute of Molecular Biology and Biotechnology, FORTH, Heraklion, Greece
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10
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Lipid biosynthesis enzyme Agpat5 in AgRP-neurons is required for insulin-induced hypoglycemia sensing and glucagon secretion. Nat Commun 2022; 13:5761. [PMID: 36180454 PMCID: PMC9525695 DOI: 10.1038/s41467-022-33484-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 09/21/2022] [Indexed: 11/13/2022] Open
Abstract
The counterregulatory response to hypoglycemia that restores normal blood glucose levels is an essential physiological function. It is initiated, in large part, by incompletely characterized brain hypoglycemia sensing neurons that trigger the secretion of counterregulatory hormones, in particular glucagon, to stimulate hepatic glucose production. In a genetic screen of recombinant inbred BXD mice we previously identified Agpat5 as a candidate regulator of hypoglycemia-induced glucagon secretion. Here, using genetic mouse models, we demonstrate that Agpat5 expressed in agouti-related peptide neurons is required for their activation by hypoglycemia, for hypoglycemia-induced vagal nerve activity, and glucagon secretion. We find that inactivation of Agpat5 leads to increased fatty acid oxidation and ATP production and that suppressing Cpt1a-dependent fatty acid import into mitochondria restores hypoglycemia sensing. Collectively, our data show that AgRP neurons are involved in the control of glucagon secretion and that Agpat5, by partitioning fatty acyl-CoAs away from mitochondrial fatty acid oxidation and ATP generation, ensures that the fall in intracellular ATP, which triggers neuronal firing, faithfully reflects changes in glycemia. During hypoglycemia, glucagon secretion is part of the mechanism needed to restore normal blood glucose levels. Here, Strembitska et al. report that sensing of hypoglycemia by AgRP neurons requires Agpat5, an enzyme which prevents fatty acids from entering the mitochondria for ATP production, ensuring correct neuronal activation and glucagon secretion.
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11
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Dünser K, Schöller M, Rößling AK, Löfke C, Xiao N, Pařízková B, Melnik S, Rodriguez-Franco M, Stöger E, Novák O, Kleine-Vehn J. Endocytic trafficking promotes vacuolar enlargements for fast cell expansion rates in plants. eLife 2022; 11:75945. [PMID: 35686734 PMCID: PMC9187339 DOI: 10.7554/elife.75945] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 05/31/2022] [Indexed: 11/13/2022] Open
Abstract
The vacuole has a space-filling function, allowing a particularly rapid plant cell expansion with very little increase in cytosolic content (Löfke et al., 2015; Scheuring et al., 2016; Dünser et al., 2019). Despite its importance for cell size determination in plants, very little is known about the mechanisms that define vacuolar size. Here, we show that the cellular and vacuolar size expansions are coordinated. By developing a pharmacological tool, we enabled the investigation of membrane delivery to the vacuole during cellular expansion. Our data reveal that endocytic membrane sorting from the plasma membrane to the vacuole is enhanced in the course of rapid root cell expansion. While this ‘compromise’ mechanism may theoretically at first decelerate cell surface enlargements, it fuels vacuolar expansion and, thereby, ensures the coordinated augmentation of vacuolar occupancy in dynamically expanding plant cells.
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Affiliation(s)
- Kai Dünser
- Molecular Plant Physiology (MoPP), Faculty of Biology, University of Freiburg, Freiburg, Germany.,Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria.,Center for Integrative Biological Signalling Studies (CIBSS), University of Freiburg, Freiburg, Germany
| | - Maria Schöller
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Ann-Kathrin Rößling
- Molecular Plant Physiology (MoPP), Faculty of Biology, University of Freiburg, Freiburg, Germany.,Center for Integrative Biological Signalling Studies (CIBSS), University of Freiburg, Freiburg, Germany
| | - Christian Löfke
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Nannan Xiao
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Barbora Pařízková
- Laboratory of Growth Regulators, Institute of Experimental Botany of the Czech Academy of Sciences and Faculty of Science of Palacký University, Olomouc, Czech Republic
| | - Stanislav Melnik
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | | | - Eva Stöger
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Ondřej Novák
- Laboratory of Growth Regulators, Institute of Experimental Botany of the Czech Academy of Sciences and Faculty of Science of Palacký University, Olomouc, Czech Republic
| | - Jürgen Kleine-Vehn
- Molecular Plant Physiology (MoPP), Faculty of Biology, University of Freiburg, Freiburg, Germany.,Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria.,Center for Integrative Biological Signalling Studies (CIBSS), University of Freiburg, Freiburg, Germany
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12
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Santella A, Kolotuev I, Kizilyaprak C, Bao Z. Cross-modality synthesis of EM time series and live fluorescence imaging. eLife 2022; 11:77918. [PMID: 35666127 PMCID: PMC9213002 DOI: 10.7554/elife.77918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 06/05/2022] [Indexed: 11/13/2022] Open
Abstract
Analyses across imaging modalities allow the integration of complementary spatiotemporal information about brain development, structure, and function. However, systematic atlasing across modalities is limited by challenges to effective image alignment. We combine highly spatially resolved electron microscopy (EM) and highly temporally resolved time-lapse fluorescence microscopy (FM) to examine the emergence of a complex nervous system in Caenorhabditis elegans embryogenesis. We generate an EM time series at four classic developmental stages and create a landmark-based co-optimization algorithm for cross-modality image alignment, which handles developmental heterochrony among datasets to achieve accurate single-cell level alignment. Synthesis based on the EM series and time-lapse FM series carrying different cell-specific markers reveals critical dynamic behaviors across scales of identifiable individual cells in the emergence of the primary neuropil, the nerve ring, as well as a major sensory organ, the amphid. Our study paves the way for systematic cross-modality data synthesis in C. elegans and demonstrates a powerful approach that may be applied broadly.
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Affiliation(s)
- Anthony Santella
- Molecular Cytology Core, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Irina Kolotuev
- Electron Microscopy Facility, University of Lausanne, Lausanne, Switzerland
| | | | - Zhirong Bao
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
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13
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Yang S, Park D, Manning L, Hill SE, Cao M, Xuan Z, Gonzalez I, Dong Y, Clark B, Shao L, Okeke I, Almoril-Porras A, Bai J, De Camilli P, Colón-Ramos DA. Presynaptic autophagy is coupled to the synaptic vesicle cycle via ATG-9. Neuron 2022; 110:824-840.e10. [PMID: 35065714 PMCID: PMC9017068 DOI: 10.1016/j.neuron.2021.12.031] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 10/20/2021] [Accepted: 12/20/2021] [Indexed: 01/01/2023]
Abstract
Autophagy is a cellular degradation pathway essential for neuronal health and function. Autophagosome biogenesis occurs at synapses, is locally regulated, and increases in response to neuronal activity. The mechanisms that couple autophagosome biogenesis to synaptic activity remain unknown. In this study, we determine that trafficking of ATG-9, the only transmembrane protein in the core autophagy pathway, links the synaptic vesicle cycle with autophagy. ATG-9-positive vesicles in C. elegans are generated from the trans-Golgi network via AP-3-dependent budding and delivered to presynaptic sites. At presynaptic sites, ATG-9 undergoes exo-endocytosis in an activity-dependent manner. Mutations that disrupt endocytosis, including a lesion in synaptojanin 1 associated with Parkinson's disease, result in abnormal ATG-9 accumulation at clathrin-rich synaptic foci and defects in activity-induced presynaptic autophagy. Our findings uncover regulated key steps of ATG-9 trafficking at presynaptic sites and provide evidence that ATG-9 exo-endocytosis couples autophagosome biogenesis at presynaptic sites with the activity-dependent synaptic vesicle cycle.
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Affiliation(s)
- Sisi Yang
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and of Cell Biology, Yale University School of Medicine, 260 Whitney Avenue, YSB C167, New Haven, CT 06511, USA
| | - Daehun Park
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and of Cell Biology, Yale University School of Medicine, 260 Whitney Avenue, YSB C167, New Haven, CT 06511, USA; Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Laura Manning
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and of Cell Biology, Yale University School of Medicine, 260 Whitney Avenue, YSB C167, New Haven, CT 06511, USA
| | - Sarah E Hill
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and of Cell Biology, Yale University School of Medicine, 260 Whitney Avenue, YSB C167, New Haven, CT 06511, USA
| | - Mian Cao
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and of Cell Biology, Yale University School of Medicine, 260 Whitney Avenue, YSB C167, New Haven, CT 06511, USA; Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Zhao Xuan
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and of Cell Biology, Yale University School of Medicine, 260 Whitney Avenue, YSB C167, New Haven, CT 06511, USA
| | - Ian Gonzalez
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and of Cell Biology, Yale University School of Medicine, 260 Whitney Avenue, YSB C167, New Haven, CT 06511, USA
| | - Yongming Dong
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Benjamin Clark
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and of Cell Biology, Yale University School of Medicine, 260 Whitney Avenue, YSB C167, New Haven, CT 06511, USA
| | - Lin Shao
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and of Cell Biology, Yale University School of Medicine, 260 Whitney Avenue, YSB C167, New Haven, CT 06511, USA
| | - Ifechukwu Okeke
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and of Cell Biology, Yale University School of Medicine, 260 Whitney Avenue, YSB C167, New Haven, CT 06511, USA
| | - Agustin Almoril-Porras
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and of Cell Biology, Yale University School of Medicine, 260 Whitney Avenue, YSB C167, New Haven, CT 06511, USA
| | - Jihong Bai
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Pietro De Camilli
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and of Cell Biology, Yale University School of Medicine, 260 Whitney Avenue, YSB C167, New Haven, CT 06511, USA; Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA; Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Daniel A Colón-Ramos
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Departments of Neuroscience and of Cell Biology, Yale University School of Medicine, 260 Whitney Avenue, YSB C167, New Haven, CT 06511, USA; Instituto de Neurobiología José del Castillo, Recinto de Ciencias Médicas, Universidad de Puerto Rico, 201 Boulevard del Valle, San Juan, PR 00901, USA; Wu Tsai Institute, Yale University, New Haven, CT 06510, USA.
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14
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Rohrbach A, Caron E, Dali R, Brunner M, Pasquettaz R, Kolotuev I, Santoni F, Thorens B, Langlet F. Ablation of glucokinase-expressing tanycytes impacts energy balance and increases adiposity in mice. Mol Metab 2021; 53:101311. [PMID: 34325016 PMCID: PMC8379510 DOI: 10.1016/j.molmet.2021.101311] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 07/20/2021] [Indexed: 01/06/2023] Open
Abstract
Objectives Glucokinase (GCK) is critical for glucosensing. In rats, GCK is expressed in hypothalamic tanycytes and appears to play an essential role in feeding behavior. In this study, we investigated the distribution of GCK-expressing tanycytes in mice and their role in the regulation of energy balance. Methods In situ hybridization, reporter gene assay, and immunohistochemistry were used to assess GCK expression along the third ventricle in mice. To evaluate the impact of GCK-expressing tanycytes on arcuate neuron function and mouse physiology, Gck deletion along the ventricle was achieved using loxP/Cre recombinase technology in adult mice. Results GCK expression was low along the third ventricle, but detectable in tanycytes facing the ventromedial arcuate nucleus from bregma −1.5 to −2.2. Gck deletion induced the death of this tanycyte subgroup through the activation of the BAD signaling pathway. The ablation of GCK-expressing tanycytes affected different aspects of energy balance, leading to an increase in adiposity in mice. This phenotype was systematically associated with a defect in NPY neuron function. In contrast, the regulation of glucose homeostasis was mostly preserved, except for glucoprivic responses. Conclusions This study describes the role of GCK in tanycyte biology and highlights the impact of tanycyte loss on the regulation of energy balance. vmARH tanycytes express glucokinase. Glucokinase deletion in tanycytes induces cell death. Ablation of vmARH tanycytes alters energy balance and adiposity. Ablation of vmARH tanycytes alters NPY neuron function.
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Affiliation(s)
- Antoine Rohrbach
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland; Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Emilie Caron
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S, 1172, Lille, France
| | - Rafik Dali
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Maxime Brunner
- Service of Endocrinology, Diabetology, and Metabolism, Lausanne University Hospital, Faculty of Biology and Medicine, 1011, Lausanne, Switzerland
| | - Roxane Pasquettaz
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Irina Kolotuev
- Electron Microscopy Facility, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Federico Santoni
- Service of Endocrinology, Diabetology, and Metabolism, Lausanne University Hospital, Faculty of Biology and Medicine, 1011, Lausanne, Switzerland
| | - Bernard Thorens
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Fanny Langlet
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland; Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
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15
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Kato M, Kolotuev I, Cunha A, Gharib S, Sternberg PW. Extrasynaptic acetylcholine signaling through a muscarinic receptor regulates cell migration. Proc Natl Acad Sci U S A 2021; 118:e1904338118. [PMID: 33361149 PMCID: PMC7817160 DOI: 10.1073/pnas.1904338118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Acetylcholine (ACh) promotes various cell migrations in vitro, but there are few investigations into this nonsynaptic role of ACh signaling in vivo. Here we investigate the function of a muscarinic receptor on an epithelial cell migration in Caenorhabditis elegans We show that the migratory gonad leader cell, the linker cell (LC), uses an M1/M3/M5-like muscarinic ACh receptor GAR-3 to receive extrasynaptic ACh signaling from cholinergic neurons for its migration. Either the loss of the GAR-3 receptor in the LC or the inhibition of ACh release from cholinergic neurons resulted in migratory path defects. The overactivation of the GAR-3 muscarinic receptor caused the LC to reverse its orientation through its downstream effectors Gαq/egl-30, PLCβ/egl-8, and TRIO/unc-73 This reversal response only occurred in the fourth larval stage, which corresponds to the developmental time when the GAR-3::yellow fluorescent protein receptor in the membrane relocalizes from a uniform to an asymmetric distribution. These findings suggest a role for the GAR-3 muscarinic receptor in determining the direction of LC migration.
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Affiliation(s)
- Mihoko Kato
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Irina Kolotuev
- Electron Microscopy Facility, University of Lausanne, Quartier Sorge-Biophore, CH-1015 Lausanne, Switzerland
| | - Alexandre Cunha
- Center for Advanced Methods in Biological Image Analysis, California Institute of Technology, Pasadena, CA 91125
| | - Shahla Gharib
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Paul W Sternberg
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125;
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16
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Homeostatic mini-intestines through scaffold-guided organoid morphogenesis. Nature 2020; 585:574-578. [PMID: 32939089 DOI: 10.1038/s41586-020-2724-8] [Citation(s) in RCA: 332] [Impact Index Per Article: 83.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 06/24/2020] [Indexed: 12/12/2022]
Abstract
Epithelial organoids, such as those derived from stem cells of the intestine, have great potential for modelling tissue and disease biology1-4. However, the approaches that are used at present to derive these organoids in three-dimensional matrices5,6 result in stochastically developing tissues with a closed, cystic architecture that restricts lifespan and size, limits experimental manipulation and prohibits homeostasis. Here, by using tissue engineering and the intrinsic self-organization properties of cells, we induce intestinal stem cells to form tube-shaped epithelia with an accessible lumen and a similar spatial arrangement of crypt- and villus-like domains to that in vivo. When connected to an external pumping system, the mini-gut tubes are perfusable; this allows the continuous removal of dead cells to prolong tissue lifespan by several weeks, and also enables the tubes to be colonized with microorganisms for modelling host-microorganism interactions. The mini-intestines include rare, specialized cell types that are seldom found in conventional organoids. They retain key physiological hallmarks of the intestine and have a notable capacity to regenerate. Our concept for extrinsically guiding the self-organization of stem cells into functional organoids-on-a-chip is broadly applicable and will enable the attainment of more physiologically relevant organoid shapes, sizes and functions.
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17
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Pasquettaz R, Kolotuev I, Rohrbach A, Gouelle C, Pellerin L, Langlet F. Peculiar protrusions along tanycyte processes face diverse neural and nonneural cell types in the hypothalamic parenchyma. J Comp Neurol 2020; 529:553-575. [PMID: 32515035 PMCID: PMC7818493 DOI: 10.1002/cne.24965] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 05/22/2020] [Accepted: 05/27/2020] [Indexed: 12/15/2022]
Abstract
Tanycytes are highly specialized ependymal cells that line the bottom and the lateral walls of the third ventricle. In contact with the cerebrospinal fluid through their cell bodies, they send processes into the arcuate nucleus, the ventromedial nucleus, and the dorsomedial nucleus of the hypothalamus. In the present work, we combined transgenic and immunohistochemical approaches to investigate the neuroanatomical associations between tanycytes and neural cells present in the hypothalamic parenchyma, in particular in the arcuate nucleus. The specific expression of tdTomato in tanycytes first allowed the observation of peculiar subcellular protrusions along tanycyte processes and at their endfeet such as spines, swelling, en passant boutons, boutons, or claws. Interestingly, these protrusions contact different neural cells in the brain parenchyma including blood vessels and neurons, and in particular NPY and POMC neurons in the arcuate nucleus. Using both fluorescent and electron microscopy, we finally observed that these tanycyte protrusions contain ribosomes, mitochondria, diverse vesicles, and transporters, suggesting dense tanycyte/neuron and tanycyte/blood vessel communications. Altogether, our results lay the neuroanatomical basis for tanycyte/neural cell interactions, which will be useful to further understand cell-to-cell communications involved in the regulation of neuroendocrine functions.
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Affiliation(s)
- Roxane Pasquettaz
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Irina Kolotuev
- Electron Microscopy Facility, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Antoine Rohrbach
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Cathy Gouelle
- Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Luc Pellerin
- Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.,Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536 CNRS, LabEx TRAIL-IBIO, Université de Bordeaux, Bordeaux Cedex, France.,Inserm U1082, Universite de Poitiers, Poitiers Cedex, France
| | - Fanny Langlet
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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18
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Mumbauer S, Pascual J, Kolotuev I, Hamaratoglu F. Ferritin heavy chain protects the developing wing from reactive oxygen species and ferroptosis. PLoS Genet 2019; 15:e1008396. [PMID: 31568497 PMCID: PMC6786644 DOI: 10.1371/journal.pgen.1008396] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 10/10/2019] [Accepted: 09/02/2019] [Indexed: 01/06/2023] Open
Abstract
The interplay between signalling pathways and metabolism is crucial for tissue growth. Yet, it remains poorly understood. Here, we studied the consequences of modulating iron metabolism on the growth of Drosophila imaginal discs. We find that reducing the levels of the ferritin heavy chain in the larval wing discs leads to drastic growth defects, whereas light chain depletion causes only minor defects. Mutant cell clones for the heavy chain lack the ability to compete against Minute mutant cells. Reactive oxygen species (ROS) accumulate in wing discs with reduced heavy chain levels, causing severe mitochondrial defects and ferroptosis. Preventing ROS accumulation alleviates some of the growth defects. We propose that the increased expression of ferritin in hippo mutant cells may protect against ROS accumulation. Despite being vital, the role of metals in biology is often overlooked. Specifically, how iron storage contributes to development remains unclear. Here, we dissected the function of the cellular iron storage complex, Ferritin, during development of a model organ, the fly wing. We took a genetic approach to uncover the role of both the heavy and light chains of Ferritin. Targeting the heavy chain consistently produced drastic growth defects in larval discs and adult wings. Moreover, lower levels of the heavy chain led to formation of reactive oxygen species (ROS) and preventing ROS accumulation alleviated the accompanying growth defects. We also observed hallmarks of ferroptosis, an iron dependent non-apoptotic cell death, upon knockdown of the heavy chain. By contrast, reducing the levels of the light chain was tolerable. This is surprising because the individual components of Ferritin were thought to function exclusively as part of the complex. Yet, the heavy chain alone encompasses the ferroxidase center, which is essential for iron loading. All together, we propose that the Ferritin heavy chain functions as an antioxidant and protects the developing organs from ferroptosis.
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Affiliation(s)
- Simone Mumbauer
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Justine Pascual
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Irina Kolotuev
- Electron Microscopy Facility, University of Lausanne, Lausanne, Switzerland
| | - Fisun Hamaratoglu
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
- * E-mail:
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19
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Low IIC, Williams CR, Chong MK, McLachlan IG, Wierbowski BM, Kolotuev I, Heiman MG. Morphogenesis of neurons and glia within an epithelium. Development 2019; 146:dev171124. [PMID: 30683663 PMCID: PMC6398450 DOI: 10.1242/dev.171124] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Accepted: 01/15/2019] [Indexed: 12/13/2022]
Abstract
To sense the outside world, some neurons protrude across epithelia, the cellular barriers that line every surface of our bodies. To study the morphogenesis of such neurons, we examined the C. elegans amphid, in which dendrites protrude through a glial channel at the nose. During development, amphid dendrites extend by attaching to the nose via DYF-7, a type of protein typically found in epithelial apical ECM. Here, we show that amphid neurons and glia exhibit epithelial properties, including tight junctions and apical-basal polarity, and develop in a manner resembling other epithelia. We find that DYF-7 is a fibril-forming apical ECM component that promotes formation of the tube-shaped glial channel, reminiscent of roles for apical ECM in other narrow epithelial tubes. We also identify a requirement for FRM-2, a homolog of EPBL15/moe/Yurt that promotes epithelial integrity in other systems. Finally, we show that other environmentally exposed neurons share a requirement for DYF-7. Together, our results suggest that these neurons and glia can be viewed as part of an epithelium continuous with the skin, and are shaped by mechanisms shared with other epithelia.
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Affiliation(s)
- Isabel I C Low
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA
| | - Claire R Williams
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA
| | - Megan K Chong
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA
| | - Ian G McLachlan
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA
| | - Bradley M Wierbowski
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA
| | - Irina Kolotuev
- Université de Rennes 1, Plateforme microscopie électronique, 35043 Rennes, France
| | - Maxwell G Heiman
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA
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20
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Mosa MH, Nicolle O, Maschalidi S, Sepulveda FE, Bidaud-Meynard A, Menche C, Michels BE, Michaux G, de Saint Basile G, Farin HF. Dynamic Formation of Microvillus Inclusions During Enterocyte Differentiation in Munc18-2-Deficient Intestinal Organoids. Cell Mol Gastroenterol Hepatol 2018; 6:477-493.e1. [PMID: 30364784 PMCID: PMC6198061 DOI: 10.1016/j.jcmgh.2018.08.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 08/02/2018] [Indexed: 12/25/2022]
Abstract
BACKGROUND & AIMS Microvillus inclusion disease (MVID) is a congenital intestinal malabsorption disorder caused by defective apical vesicular transport. Existing cellular models do not fully recapitulate this heterogeneous pathology. The aim of this study was to characterize 3-dimensional intestinal organoids that continuously generate polarized absorptive cells as an accessible and relevant model to investigate MVID. METHODS Intestinal organoids from Munc18-2/Stxbp2-null mice that are deficient for apical vesicular transport were subjected to enterocyte-specific differentiation protocols. Lentiviral rescue experiments were performed using human MUNC18-2 variants. Apical trafficking and microvillus formation were characterized by confocal and transmission electron microscopy. Spinning disc time-lapse microscopy was used to document the lifecycle of microvillus inclusions. RESULTS Loss of Munc18-2/Stxbp2 recapitulated the pathologic features observed in patients with MUNC18-2 deficiency. The defects were fully restored by transgenic wild-type human MUNC18-2 protein, but not the patient variant (P477L). Importantly, we discovered that the MVID phenotype was correlated with the degree of enterocyte differentiation: secretory vesicles accumulated already in crypt progenitors, while differentiated enterocytes showed an apical tubulovesicular network and enlarged lysosomes. Upon prolonged enterocyte differentiation, cytoplasmic F-actin-positive foci were observed that further progressed into classic microvillus inclusions. Time-lapse microscopy showed their dynamic formation by intracellular maturation or invagination of the apical or basolateral plasma membrane. CONCLUSIONS We show that prolonged enterocyte-specific differentiation is required to recapitulate the entire spectrum of MVID. Primary organoids can provide a powerful model for this heterogeneous pathology. Formation of microvillus inclusions from multiple membrane sources showed an unexpected dynamic of the enterocyte brush border.
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Key Words
- 3D, 3-dimensional
- Apical Vesicular Transport
- Brush Border Formation
- DAPI, 4′,6-diamidino-2-phenylindole
- Disease Modeling
- EGFP, enhanced green fluorescent protein
- FHL5, familial hemophagocytic lymphohistiocytosis type 5
- IWP-2, inhibitor of WNT production-2
- KO, knock-out
- MVID, microvillus inclusion disease
- MVIs, microvillus inclusions
- Microvillus Atrophy
- PBS, phosphate-buffered saline
- STXBP2, syntaxin binding protein 2
- Stx3, syntaxin 3
- TEM, transmission electron microscopy
- VPA, valproic acid
- WT, wild-type
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Affiliation(s)
- Mohammed H. Mosa
- German Cancer Consortium (Deutsches Konsortium für Translationale Krebsforschung), Heidelberg, Germany,Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany,German Cancer Research Center (Deutsches Krebsforschungszentrum), Heidelberg, Germany
| | - Ophélie Nicolle
- University Rennes, Centre national de la recherche scientifique, Institut de Génétique et Développement de Rennes UMR6290, Rennes, France
| | - Sophia Maschalidi
- INSERM UMR1163, Laboratory of Normal and Pathological Homeostasis of the Immune System, Paris, France,Imagine Institute, Paris Descartes University–Sorbonne Paris Cité, Paris, France
| | - Fernando E. Sepulveda
- INSERM UMR1163, Laboratory of Normal and Pathological Homeostasis of the Immune System, Paris, France,Imagine Institute, Paris Descartes University–Sorbonne Paris Cité, Paris, France
| | - Aurelien Bidaud-Meynard
- University Rennes, Centre national de la recherche scientifique, Institut de Génétique et Développement de Rennes UMR6290, Rennes, France
| | - Constantin Menche
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany
| | - Birgitta E. Michels
- German Cancer Consortium (Deutsches Konsortium für Translationale Krebsforschung), Heidelberg, Germany,Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany,German Cancer Research Center (Deutsches Krebsforschungszentrum), Heidelberg, Germany,Faculty of Biological Sciences, Goethe University Frankfurt, Germany
| | - Grégoire Michaux
- University Rennes, Centre national de la recherche scientifique, Institut de Génétique et Développement de Rennes UMR6290, Rennes, France,Correspondence Address correspondence to: Grégoire Michaux, PhD, University Rennes, Institut de Génétique et Développement de Rennes, Rennes, France.
| | - Geneviève de Saint Basile
- INSERM UMR1163, Laboratory of Normal and Pathological Homeostasis of the Immune System, Paris, France,Imagine Institute, Paris Descartes University–Sorbonne Paris Cité, Paris, France,Centre d’Etudes des Déficites Immunitaires, Assistance Publique-Hôpitaux de Paris, France,Geneviève de Saint Basile, MD, PhD, INSERM, Paris, France.
| | - Henner F. Farin
- German Cancer Consortium (Deutsches Konsortium für Translationale Krebsforschung), Heidelberg, Germany,Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany,German Cancer Research Center (Deutsches Krebsforschungszentrum), Heidelberg, Germany,Henner F. Farin, PhD, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany.
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21
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Lee KY, Green RA, Gutierrez E, Gomez-Cavazos JS, Kolotuev I, Wang S, Desai A, Groisman A, Oegema K. CYK-4 functions independently of its centralspindlin partner ZEN-4 to cellularize oocytes in germline syncytia. eLife 2018; 7:36919. [PMID: 29989548 PMCID: PMC6056237 DOI: 10.7554/elife.36919] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 07/09/2018] [Indexed: 12/15/2022] Open
Abstract
Throughout metazoans, germ cells undergo incomplete cytokinesis to form syncytia connected by intercellular bridges. Gamete formation ultimately requires bridge closure, yet how bridges are reactivated to close is not known. The most conserved bridge component is centralspindlin, a complex of the Rho family GTPase-activating protein (GAP) CYK-4/MgcRacGAP and the microtubule motor ZEN-4/kinesin-6. Here, we show that oocyte production by the syncytial Caenorhabditis elegans germline requires CYK-4 but not ZEN-4, which contrasts with cytokinesis, where both are essential. Longitudinal imaging after conditional inactivation revealed that CYK-4 activity is important for oocyte cellularization, but not for the cytokinesis-like events that generate syncytial compartments. CYK-4’s lipid-binding C1 domain and the GTPase-binding interface of its GAP domain were both required to target CYK-4 to intercellular bridges and to cellularize oocytes. These results suggest that the conserved C1-GAP region of CYK-4 constitutes a targeting module required for closure of intercellular bridges in germline syncytia.
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Affiliation(s)
- Kian-Yong Lee
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, United States
| | - Rebecca A Green
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, United States
| | - Edgar Gutierrez
- Department of Physics, University of California, San Diego, La Jolla, United States
| | - J Sebastian Gomez-Cavazos
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, United States
| | - Irina Kolotuev
- Microscopy Rennes Imaging Center and Biosit, University of Rennes 1, Rennes, France
| | - Shaohe Wang
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, United States
| | - Arshad Desai
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, United States
| | - Alex Groisman
- Department of Physics, University of California, San Diego, La Jolla, United States
| | - Karen Oegema
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, United States
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22
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Burel A, Lavault MT, Chevalier C, Gnaegi H, Prigent S, Mucciolo A, Dutertre S, Humbel BM, Guillaudeux T, Kolotuev I. A targeted 3D EM and correlative microscopy method using SEM array tomography. Development 2018; 145:dev.160879. [PMID: 29802150 DOI: 10.1242/dev.160879] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 05/16/2018] [Indexed: 12/15/2022]
Abstract
Using electron microscopy to localize rare cellular events or structures in complex tissue is challenging. Correlative light and electron microscopy procedures have been developed to link fluorescent protein expression with ultrastructural resolution. Here, we present an optimized scanning electron microscopy (SEM) workflow for volumetric array tomography for asymmetric samples and model organisms (Caenorhabditis elegans, Drosophila melanogaster, Danio rerio). We modified a diamond knife to simplify serial section array acquisition with minimal artifacts. After array acquisition, the arrays were transferred to a glass coverslip or silicon wafer support. Using light microscopy, the arrays were screened rapidly for initial recognition of global anatomical features (organs or body traits). Then, using SEM, an in-depth study of the cells and/or organs of interest was performed. Our manual and automatic data acquisition strategies make 3D data acquisition and correlation simpler and more precise than alternative methods. This method can be used to address questions in cell and developmental biology that require the efficient identification of a labeled cell or organelle.
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Affiliation(s)
- Agnes Burel
- University of Rennes 1, UMS Biosit, MRic, 35043 Rennes, France
| | | | | | | | - Sylvain Prigent
- University of Rennes 1, UMS Biosit, MRic, 35043 Rennes, France
| | - Antonio Mucciolo
- University of Lausanne, Faculté de biologie et de médecine, Electron Microscopy Facility, CH-1015 Lausanne, Switzerland
| | | | - Bruno M Humbel
- University of Lausanne, Faculté de biologie et de médecine, Electron Microscopy Facility, CH-1015 Lausanne, Switzerland
| | | | - Irina Kolotuev
- University of Rennes 1, UMS Biosit, MRic, 35043 Rennes, France .,University of Lausanne, Faculté de biologie et de médecine, Electron Microscopy Facility, CH-1015 Lausanne, Switzerland
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23
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Daniel E, Daudé M, Kolotuev I, Charish K, Auld V, Le Borgne R. Coordination of Septate Junctions Assembly and Completion of Cytokinesis in Proliferative Epithelial Tissues. Curr Biol 2018; 28:1380-1391.e4. [PMID: 29706514 DOI: 10.1016/j.cub.2018.03.034] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 12/26/2017] [Accepted: 03/15/2018] [Indexed: 01/22/2023]
Abstract
How permeability barrier function is maintained when epithelial cells divide is largely unknown. Here, we have investigated how the bicellular septate junctions (BSJs) and tricellular septate junctions (TSJs) are remodeled throughout completion of cytokinesis in Drosophila epithelia. We report that, following cytokinetic ring constriction, the midbody assembles, matures within SJs, and is displaced basally in two phases. In a first slow phase, the neighboring cells remain connected to the dividing cells by means of SJ-containing membrane protrusions pointing to the maturing midbody. Fluorescence recovery after photobleaching (FRAP) experiments revealed that SJs within the membrane protrusions correspond to the old SJs that were present prior to cytokinesis. In contrast, new SJs are assembled below the adherens junctions and spread basally to build a new belt of SJs in a manner analogous to a conveyor belt. Loss of function of a core BSJ component, the Na+/K+-ATPase pump Nervana 2 subunit, revealed that the apical-to-basal spread of BSJs drives the basal displacement of the midbody. In contrast, loss of the TSJ protein Bark beetle indicated that remodeling of TSJs is rate limiting and slowed down midbody migration. In the second phase, once the belt of SJs is assembled, the basal displacement of the midbody is accelerated and ultimately leads to abscission. This last step is temporally uncoupled from the remodeling of SJs. We propose that cytokinesis in epithelia involves the coordinated polarized assembly and remodeling of SJs both in the dividing cell and its neighbors to ensure the maintenance of permeability barrier integrity in proliferative epithelia.
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Affiliation(s)
- Emeline Daniel
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, 35000 Rennes, France
| | - Marion Daudé
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, 35000 Rennes, France
| | - Irina Kolotuev
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, 35000 Rennes, France
| | - Kristi Charish
- Department of Zoology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Vanessa Auld
- Department of Zoology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Roland Le Borgne
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, 35000 Rennes, France; Équipe Labellisée Ligue Nationale contre le Cancer.
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24
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Loyer N, Kolotuev I, Pinot M, Le Borgne R. Drosophila E-cadherin is required for the maintenance of ring canals anchoring to mechanically withstand tissue growth. Proc Natl Acad Sci U S A 2015; 112:12717-22. [PMID: 26424451 PMCID: PMC4611665 DOI: 10.1073/pnas.1504455112] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Intercellular bridges called "ring canals" (RCs) resulting from incomplete cytokinesis play an essential role in intercellular communication in somatic and germinal tissues. During Drosophila oogenesis, RCs connect the maturing oocyte to nurse cells supporting its growth. Despite numerous genetic screens aimed at identifying genes involved in RC biogenesis and maturation, how RCs anchor to the plasma membrane (PM) throughout development remains unexplained. In this study, we report that the clathrin adaptor protein 1 (AP-1) complex, although dispensable for the biogenesis of RCs, is required for the maintenance of the anchorage of RCs to the PM to withstand the increased membrane tension associated with the exponential tissue growth at the onset of vitellogenesis. Here we unravel the mechanisms by which AP-1 enables the maintenance of RCs' anchoring to the PM during size expansion. We show that AP-1 regulates the localization of the intercellular adhesion molecule E-cadherin and that loss of AP-1 causes the disappearance of the E-cadherin-containing adhesive clusters surrounding the RCs. E-cadherin itself is shown to be required for the maintenance of the RCs' anchorage, a function previously unrecognized because of functional compensation by N-cadherin. Scanning block-face EM combined with transmission EM analyses reveals the presence of interdigitated, actin- and Moesin-positive, microvilli-like structures wrapping the RCs. Thus, by modulating E-cadherin trafficking, we show that the sustained E-cadherin-dependent adhesion organizes the microvilli meshwork and ensures the proper attachment of RCs to the PM, thereby counteracting the increasing membrane tension induced by exponential tissue growth.
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Affiliation(s)
- Nicolas Loyer
- CNRS, UMR 6290, F-35000 Rennes, France; Institut de Génétique et Développement de Rennes, Université Rennes 1, F-35000 Rennes, France; Equipe Labellisée Ligue Nationale Contre le Cancer, F-35000 Rennes, France
| | - Irina Kolotuev
- CNRS, UMR 6290, F-35000 Rennes, France; Institut de Génétique et Développement de Rennes, Université Rennes 1, F-35000 Rennes, France; Equipe Labellisée Ligue Nationale Contre le Cancer, F-35000 Rennes, France; CNRS, Structure Fédérative de Recherche BIOSIT, Microscopy Rennes Imaging Center-Electron Microscopy Facility, F-35000 Rennes, France
| | - Mathieu Pinot
- CNRS, UMR 6290, F-35000 Rennes, France; Institut de Génétique et Développement de Rennes, Université Rennes 1, F-35000 Rennes, France; Equipe Labellisée Ligue Nationale Contre le Cancer, F-35000 Rennes, France
| | - Roland Le Borgne
- CNRS, UMR 6290, F-35000 Rennes, France; Institut de Génétique et Développement de Rennes, Université Rennes 1, F-35000 Rennes, France; Equipe Labellisée Ligue Nationale Contre le Cancer, F-35000 Rennes, France;
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25
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Li MW, Zhou L, Lam HM. Paraformaldehyde Fixation May Lead to Misinterpretation of the Subcellular Localization of Plant High Mobility Group Box Proteins. PLoS One 2015; 10:e0135033. [PMID: 26270959 PMCID: PMC4535772 DOI: 10.1371/journal.pone.0135033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 07/16/2015] [Indexed: 12/21/2022] Open
Abstract
Arabidopsis High Mobility Group Box (HMBG) proteins were previously found associated with the interphase chromatin but not the metaphase chromosome. However, these studies are usually based on immunolocalization analysis involving paraformaldehyde fixation. Paraformaldehyde fixation has been widely adapted to preserved cell morphology before immunofluorescence staining. On one hand, the processed cells are no longer living. On the other hand, the processing may lead to misinterpretation of localization. HMGBs from Arabidopsis were fused with enhanced green fluorescence protein (EGFP) and transformed into tobacco BY-2 cells. Basically, the localization of these HMGB proteins detected with EGFP fluorescence in interphase agreed with previous publications. Upon 4% paraformaldehyde fixation, AtHMGB1 was found associated with interphase but not the metaphase chromosomes as previously reported. However, when EGFP fluorescence signal was directly observed under confocal microscope without fixation, association of AtHMGB1 with metaphase chromosomes can be detected. Paraformaldehyde fixation led to dissociation of EGFP tagged AtHMBG1 protein from metaphase chromosomes. This kind of pre-processing of live specimen may lead to dissociation of protein-protein or protein-nucleic acid interaction. Therefore, using of EGFP fusion proteins in live specimen is a better way to determine the correct localization and interaction of proteins.
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Affiliation(s)
- Man-Wah Li
- Centre for Soybean Research of the Partner State Key Laboratory of Agrobiotechnology and School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Liang Zhou
- Centre for Soybean Research of the Partner State Key Laboratory of Agrobiotechnology and School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
- Department of Radiation Medicine, School of Public Health and Tropic Medicine, Southern Medical University, Guangzhou, Guangdong, People’s Republic of China
| | - Hon-Ming Lam
- Centre for Soybean Research of the Partner State Key Laboratory of Agrobiotechnology and School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
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26
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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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27
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Starborg T, Kadler KE. Serial block face-scanning electron microscopy: A tool for studying embryonic development at the cell-matrix interface. ACTA ACUST UNITED AC 2015; 105:9-18. [DOI: 10.1002/bdrc.21087] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 02/18/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Tobias Starborg
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences; University of Manchester, Michael Smith Building; Oxford Road Manchester United Kingdom
| | - Karl E. Kadler
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences; University of Manchester, Michael Smith Building; Oxford Road Manchester United Kingdom
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