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Link F, Borges A, Karo O, Jungblut M, Müller T, Meyer-Natus E, Krüger T, Sachs S, Jones NG, Morphew M, Sauer M, Stigloher C, McIntosh JR, Engstler M. Continuous endosomes form functional subdomains and orchestrate rapid membrane trafficking in trypanosomes. eLife 2024; 12:RP91194. [PMID: 38619530 PMCID: PMC11018342 DOI: 10.7554/elife.91194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024] Open
Abstract
Endocytosis is a common process observed in most eukaryotic cells, although its complexity varies among different organisms. In Trypanosoma brucei, the endocytic machinery is under special selective pressure because rapid membrane recycling is essential for immune evasion. This unicellular parasite effectively removes host antibodies from its cell surface through hydrodynamic drag and fast endocytic internalization. The entire process of membrane recycling occurs exclusively through the flagellar pocket, an extracellular organelle situated at the posterior pole of the spindle-shaped cell. The high-speed dynamics of membrane flux in trypanosomes do not seem compatible with the conventional concept of distinct compartments for early endosomes (EE), late endosomes (LE), and recycling endosomes (RE). To investigate the underlying structural basis for the remarkably fast membrane traffic in trypanosomes, we employed advanced techniques in light and electron microscopy to examine the three-dimensional architecture of the endosomal system. Our findings reveal that the endosomal system in trypanosomes exhibits a remarkably intricate structure. Instead of being compartmentalized, it constitutes a continuous membrane system, with specific functions of the endosome segregated into membrane subdomains enriched with classical markers for EE, LE, and RE. These membrane subdomains can partly overlap or are interspersed with areas that are negative for endosomal markers. This continuous endosome allows fast membrane flux by facilitated diffusion that is not slowed by multiple fission and fusion events.
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Affiliation(s)
- Fabian Link
- Department of Cell & Developmental Biology, Biocentre, University of WürzburgWürzburgGermany
| | - Alyssa Borges
- Department of Cell & Developmental Biology, Biocentre, University of WürzburgWürzburgGermany
| | - Oliver Karo
- Department of Cell & Developmental Biology, Biocentre, University of WürzburgWürzburgGermany
| | - Marvin Jungblut
- Department of Biotechnology & Biophysics, Biocentre, University of WürzburgWürzburgGermany
| | - Thomas Müller
- Department of Cell & Developmental Biology, Biocentre, University of WürzburgWürzburgGermany
| | - Elisabeth Meyer-Natus
- Department of Cell & Developmental Biology, Biocentre, University of WürzburgWürzburgGermany
| | - Timothy Krüger
- Department of Cell & Developmental Biology, Biocentre, University of WürzburgWürzburgGermany
| | - Stefan Sachs
- Department of Biotechnology & Biophysics, Biocentre, University of WürzburgWürzburgGermany
| | - Nicola G Jones
- Department of Cell & Developmental Biology, Biocentre, University of WürzburgWürzburgGermany
| | - Mary Morphew
- Molecular, Cellular & Developmental Biology, University of Colorado BoulderBoulderUnited States
| | - Markus Sauer
- Department of Biotechnology & Biophysics, Biocentre, University of WürzburgWürzburgGermany
| | | | - J Richard McIntosh
- Molecular, Cellular & Developmental Biology, University of Colorado BoulderBoulderUnited States
| | - Markus Engstler
- Department of Cell & Developmental Biology, Biocentre, University of WürzburgWürzburgGermany
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Schichler D, Konle A, Spath EM, Riegler S, Klein A, Seleznev A, Jung S, Wuppermann T, Wetterich N, Borges A, Meyer-Natus E, Havlicek K, Pérez Cabrera S, Niedermüller K, Sajko S, Dohn M, Malzer X, Riemer E, Tumurbaatar T, Djinovic-Carugo K, Dong G, Janzen CJ, Morriswood B. Characterisation of TbSmee1 suggests endocytosis allows surface-bound cargo to enter the trypanosome flagellar pocket. J Cell Sci 2023; 136:jcs261548. [PMID: 37737012 PMCID: PMC10652038 DOI: 10.1242/jcs.261548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 08/11/2023] [Indexed: 09/23/2023] Open
Abstract
All endocytosis and exocytosis in the African trypanosome Trypanosoma brucei occurs at a single subdomain of the plasma membrane. This subdomain, the flagellar pocket, is a small vase-shaped invagination containing the root of the single flagellum of the cell. Several cytoskeleton-associated multiprotein complexes are coiled around the neck of the flagellar pocket on its cytoplasmic face. One of these, the hook complex, was proposed to affect macromolecule entry into the flagellar pocket lumen. In previous work, knockdown of T. brucei (Tb)MORN1, a hook complex component, resulted in larger cargo being unable to enter the flagellar pocket. In this study, the hook complex component TbSmee1 was characterised in bloodstream form T. brucei and found to be essential for cell viability. TbSmee1 knockdown resulted in flagellar pocket enlargement and impaired access to the flagellar pocket membrane by surface-bound cargo, similar to depletion of TbMORN1. Unexpectedly, inhibition of endocytosis by knockdown of clathrin phenocopied TbSmee1 knockdown, suggesting that endocytic activity itself is a prerequisite for the entry of surface-bound cargo into the flagellar pocket.
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Affiliation(s)
- Daja Schichler
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Antonia Konle
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Eva-Maria Spath
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Sina Riegler
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Alexandra Klein
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Anna Seleznev
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Sisco Jung
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Timothy Wuppermann
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Noah Wetterich
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Alyssa Borges
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Elisabeth Meyer-Natus
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Katharina Havlicek
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | | | - Korbinian Niedermüller
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Sara Sajko
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Maximilian Dohn
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Xenia Malzer
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Emily Riemer
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Tuguldur Tumurbaatar
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Kristina Djinovic-Carugo
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna Biocenter (VBC), 1030 Vienna, Austria
- Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia
- European Molecular Biology Laboratory (EMBL) Grenoble, 38000 Grenoble, France
| | - Gang Dong
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Christian J. Janzen
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Brooke Morriswood
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
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Krüger T, Maus K, Kreß V, Meyer-Natus E, Engstler M. Single-cell motile behaviour of [Formula: see text] in thin-layered fluid collectives. Eur Phys J E Soft Matter 2021; 44:37. [PMID: 33755816 PMCID: PMC7987620 DOI: 10.1140/epje/s10189-021-00052-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 03/09/2021] [Indexed: 05/14/2023]
Abstract
We describe a system for the analysis of an important unicellular eukaryotic flagellate in a confining and crowded environment. The parasite Trypanosoma brucei is arguably one of the most versatile microswimmers known. It has unique properties as a single microswimmer and shows remarkable adaptations (not only in motility, but prominently so), to its environment during a complex developmental cycle involving two different hosts. Specific life cycle stages show fascinating collective behaviour, as millions of cells can be forced to move together in extreme confinement. Our goal is to examine such motile behaviour directly in the context of the relevant environments. Therefore, for the first time, we analyse the motility behaviour of trypanosomes directly in a widely used assay, which aims to evaluate the parasites behaviour in collectives, in response to as yet unknown parameters. In a step towards understanding whether, or what type of, swarming behaviour of trypanosomes exists, we customised the assay for quantitative tracking analysis of motile behaviour on the single-cell level. We show that the migration speed of cell groups does not directly depend on single-cell velocity and that the system remains to be simplified further, before hypotheses about collective motility can be advanced.
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Affiliation(s)
- Timothy Krüger
- Lehrstuhl für Zell- und Entwicklungsbiologie, Biozentrum, Julius-Maximilians-Universität, Am Hubland, 97074, Würzburg, Germany.
| | - Katharina Maus
- Lehrstuhl für Zell- und Entwicklungsbiologie, Biozentrum, Julius-Maximilians-Universität, Am Hubland, 97074, Würzburg, Germany
| | - Verena Kreß
- Lehrstuhl für Zell- und Entwicklungsbiologie, Biozentrum, Julius-Maximilians-Universität, Am Hubland, 97074, Würzburg, Germany
| | - Elisabeth Meyer-Natus
- Lehrstuhl für Zell- und Entwicklungsbiologie, Biozentrum, Julius-Maximilians-Universität, Am Hubland, 97074, Würzburg, Germany
| | - Markus Engstler
- Lehrstuhl für Zell- und Entwicklungsbiologie, Biozentrum, Julius-Maximilians-Universität, Am Hubland, 97074, Würzburg, Germany
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Kramer S, Meyer-Natus E, Stigloher C, Thoma H, Schnaufer A, Engstler M. Parallel monitoring of RNA abundance, localization and compactness with correlative single molecule FISH on LR White embedded samples. Nucleic Acids Res 2021; 49:e14. [PMID: 33275141 PMCID: PMC7897490 DOI: 10.1093/nar/gkaa1142] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 10/16/2020] [Accepted: 11/17/2020] [Indexed: 01/19/2023] Open
Abstract
Single mRNA molecules are frequently detected by single molecule fluorescence in situ hybridization (smFISH) using branched DNA technology. While providing strong and background-reduced signals, the method is inefficient in detecting mRNAs within dense structures, in monitoring mRNA compactness and in quantifying abundant mRNAs. To overcome these limitations, we have hybridized slices of high pressure frozen, freeze-substituted and LR White embedded cells (LR White smFISH). mRNA detection is physically restricted to the surface of the resin. This enables single molecule detection of RNAs with accuracy comparable to RNA sequencing, irrespective of their abundance, while at the same time providing spatial information on RNA localization that can be complemented with immunofluorescence and electron microscopy, as well as array tomography. Moreover, LR White embedding restricts the number of available probe pair recognition sites for each mRNA to a small subset. As a consequence, differences in signal intensities between RNA populations reflect differences in RNA structures, and we show that the method can be employed to determine mRNA compactness. We apply the method to answer some outstanding questions related to trans-splicing, RNA granules and mitochondrial RNA editing in single-cellular trypanosomes and we show an example of differential gene expression in the metazoan Caenorhabditis elegans.
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Affiliation(s)
- Susanne Kramer
- Zell- und Entwicklungsbiologie, Biozentrum, Universität Würzburg, Würzburg, Germany
| | | | - Christian Stigloher
- Zell- und Entwicklungsbiologie, Biozentrum, Universität Würzburg, Würzburg, Germany.,Imaging Core Facility, Biozentrum, Universität Würzburg, Würzburg, Germany
| | - Hanna Thoma
- Zell- und Entwicklungsbiologie, Biozentrum, Universität Würzburg, Würzburg, Germany
| | - Achim Schnaufer
- Institute for Immunology & Infection Research, University of Edinburgh, Edinburgh, UK
| | - Markus Engstler
- Zell- und Entwicklungsbiologie, Biozentrum, Universität Würzburg, Würzburg, Germany
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Göb E, Meyer-Natus E, Benavente R, Alsheimer M. Expression of individual mammalian Sun1 isoforms depends on the cell type. Commun Integr Biol 2011; 4:440-2. [PMID: 21966565 DOI: 10.4161/cib.4.4.15369] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 03/04/2011] [Indexed: 11/19/2022] Open
Abstract
Mammalian Sun1 belongs to an evolutionarily conserved family of inner nuclear membrane proteins, which are known as SUN domain proteins. SUN domain proteins interact with KASH domain partners to form bridging complexes, so-called LINC complexes, that physically connect the nuclear interior to the cytoskeleton. LINC complexes are critical for nuclear integrity and play fundamental roles in nuclear positioning, shaping and movement. The mammalian genome codes for at least five different SUN domain proteins used for the formation of a number of different LINC complexes. Recently, we reported on the identification of several Sun1 isoforms, which tremendously enlarges the alternatives to form functional LINC complexes. We now confirmed that Sun1 actually exists in at least seven distinct splice variants. Besides that, we observed that expression of individual Sun1 isoforms remarkably depends on the cell type, suggesting a cell type-specific adaption of Sun1 dependent LINC complexes to specific cellular and physiological requirements.
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Affiliation(s)
- Eva Göb
- Department of Cell and Developmental Biology; Biocenter; University of Würzburg; Am Hubland, Würzburg Germany
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