51
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Haag C, Pohlmann T, Feldbrügge M. The ESCRT regulator Did2 maintains the balance between long-distance endosomal transport and endocytic trafficking. PLoS Genet 2017; 13:e1006734. [PMID: 28422978 PMCID: PMC5415202 DOI: 10.1371/journal.pgen.1006734] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 05/03/2017] [Accepted: 04/04/2017] [Indexed: 01/01/2023] Open
Abstract
In highly polarised cells, like fungal hyphae, early endosomes function in both endocytosis as well as long-distance transport of various cargo including mRNA and protein complexes. However, knowledge on the crosstalk between these seemingly different trafficking processes is scarce. Here, we demonstrate that the ESCRT regulator Did2 coordinates endosomal transport in fungal hyphae of Ustilago maydis. Loss of Did2 results in defective vacuolar targeting, less processive long-distance transport and abnormal shuttling of early endosomes. Importantly, the late endosomal protein Rab7 and vacuolar protease Prc1 exhibit increased shuttling on these aberrant endosomes suggesting defects in endosomal maturation and identity. Consistently, molecular motors fail to attach efficiently explaining the disturbed processive movement. Furthermore, the endosomal mRNP linker protein Upa1 is hardly present on endosomes resulting in defects in long-distance mRNA transport. In conclusion, the ESCRT regulator Did2 coordinates precise maturation of endosomes and thus provides the correct membrane identity for efficient endosomal long-distance transport.
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Affiliation(s)
- Carl Haag
- Heinrich Heine University Düsseldorf, Institute for Microbiology, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Thomas Pohlmann
- Heinrich Heine University Düsseldorf, Institute for Microbiology, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Michael Feldbrügge
- Heinrich Heine University Düsseldorf, Institute for Microbiology, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
- * E-mail:
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52
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Alvarado ME, Rubiano C, Calvo E, Gómez V, Wasserman M. Experimental and bioinformatic characterization of CaBP2933 an EF-Hand protein of Giardia intestinalis. Mol Biochem Parasitol 2017; 214:65-68. [PMID: 28373093 DOI: 10.1016/j.molbiopara.2017.03.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 03/27/2017] [Accepted: 03/29/2017] [Indexed: 01/17/2023]
Abstract
Giardia intestinalis is a parasite that inhabits the small intestine of humans. This parasite is a divergent eukaryote with a compact genome. The calcium ion is an essential messenger in cell signaling. Calcium's role as a messenger is mediated through calcium-binding proteins (CaBPs) that decode the message. The most important family of CaBPs is the EF-Hand protein family. In this study we have explored the role of EF-Hand protein CaBP2933. We analyzed its location, confirmed its ability to bind calcium and identified some of its interacting proteins. Take together our results suggest that CaBP2933 is involved in vesicular trafficking during encystation, via an interaction with kinesin-3 motor protein.
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Affiliation(s)
- Magda E Alvarado
- Laboratorio de Investigaciones Básicas en Bioquímica- LIBBIQ, Universidad Nacional de Colombia, Calle 44 No. 45-67, Bogotá, Colombia.
| | - Claudia Rubiano
- Laboratorio de Investigaciones Básicas en Bioquímica- LIBBIQ, Universidad Nacional de Colombia, Calle 44 No. 45-67, Bogotá, Colombia
| | - Eliana Calvo
- Laboratorio de Investigaciones Básicas en Bioquímica- LIBBIQ, Universidad Nacional de Colombia, Calle 44 No. 45-67, Bogotá, Colombia
| | - Vanessa Gómez
- Laboratorio de Investigaciones Básicas en Bioquímica- LIBBIQ, Universidad Nacional de Colombia, Calle 44 No. 45-67, Bogotá, Colombia
| | - Moisés Wasserman
- Laboratorio de Investigaciones Básicas en Bioquímica- LIBBIQ, Universidad Nacional de Colombia, Calle 44 No. 45-67, Bogotá, Colombia
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53
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Lo Presti L, Zechmann B, Kumlehn J, Liang L, Lanver D, Tanaka S, Bock R, Kahmann R. An assay for entry of secreted fungal effectors into plant cells. THE NEW PHYTOLOGIST 2017; 213:956-964. [PMID: 27716942 DOI: 10.1111/nph.14188] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/05/2016] [Indexed: 05/23/2023]
Abstract
Successful colonization of plants by prokaryotic and eukaryotic pathogens requires active effector-mediated suppression of defense responses and host tissue reprogramming. Secreted effector proteins can either display their activity in the apoplast or translocate into host cells and function therein. Although characterized in bacteria, the molecular mechanisms of effector delivery by fungal phytopathogens remain elusive. Here we report the establishment of an assay that is based on biotinylation of effectors in the host cytoplasm as hallmark of uptake. The assay exploits the ability of the bacterial biotin ligase BirA to biotinylate any protein that carries a short peptide (Avitag). It is based on the stable expression of BirA in the cytoplasm of maize plants and on engineering of Ustilago maydis strains to secrete Avitagged effectors. We demonstrate translocation of a number of effectors in the U. maydis-maize system and show data that suggest that the uptake mechanism could be rather nonspecific The assay promises to be a powerful tool for the classification of effectors as well as for the functional study of effector uptake mechanism not only in the chosen system but more generally for systems where biotrophic interactions are established.
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Affiliation(s)
- Libera Lo Presti
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Bernd Zechmann
- Center for Microscopy and Imaging, Baylor University, One Bear Place #97046, Waco, TX, 76798-7046, USA
| | - Jochen Kumlehn
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), OT Gatersleben, Corrensstrasse 3, 06466, Stadt Seeland, Germany
| | - Liang Liang
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Daniel Lanver
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Shigeyuki Tanaka
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Ralph Bock
- Department of Organelle Biology, Biotechnology and Molecular Ecophysiology, Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam, Germany
| | - Regine Kahmann
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
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54
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Cheeseman LP, Boulanger J, Bond LM, Schuh M. Two pathways regulate cortical granule translocation to prevent polyspermy in mouse oocytes. Nat Commun 2016; 7:13726. [PMID: 27991490 PMCID: PMC5187413 DOI: 10.1038/ncomms13726] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 10/27/2016] [Indexed: 12/20/2022] Open
Abstract
An egg must be fertilized by a single sperm only. To prevent polyspermy, the zona pellucida, a structure that surrounds mammalian eggs, becomes impermeable upon fertilization, preventing the entry of further sperm. The structural changes in the zona upon fertilization are driven by the exocytosis of cortical granules. These translocate from the oocyte's centre to the plasma membrane during meiosis. However, very little is known about the mechanism of cortical granule translocation. Here we investigate cortical granule transport and dynamics in live mammalian oocytes by using Rab27a as a marker. We show that two separate mechanisms drive their transport: myosin Va-dependent movement along actin filaments, and an unexpected vesicle hitchhiking mechanism by which cortical granules bind to Rab11a vesicles powered by myosin Vb. Inhibiting cortical granule translocation severely impaired the block to sperm entry, suggesting that translocation defects could contribute to miscarriages that are caused by polyspermy.
Mammalian eggs release cortical granules to avoid being fertilized by more than a single sperm as polyspermy results in nonviable embryos. Here, the authors describe the mechanism driving translocation of the granules to the cortex in the mouse egg and show this process is essential to prevent polyspermy.
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Affiliation(s)
- Liam P Cheeseman
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Jérôme Boulanger
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Lisa M Bond
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Melina Schuh
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.,Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany
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55
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Abstract
Filamentous fungi have proven to be a better-suited model system than unicellular yeasts in analyses of cellular processes such as polarized growth, exocytosis, endocytosis, and cytoskeleton-based organelle traffic. For example, the filamentous fungus
Neurospora crassa develops a variety of cellular forms. Studying the molecular basis of these forms has led to a better, yet incipient, understanding of polarized growth. Polarity factors as well as Rho GTPases, septins, and a localized delivery of vesicles are the central elements described so far that participate in the shift from isotropic to polarized growth. The growth of the cell wall by apical biosynthesis and remodeling of polysaccharide components is a key process in hyphal morphogenesis. The coordinated action of motor proteins and Rab GTPases mediates the vesicular journey along the hyphae toward the apex, where the exocyst mediates vesicle fusion with the plasma membrane. Cytoplasmic microtubules and actin microfilaments serve as tracks for the transport of vesicular carriers as well as organelles in the tubular cell, contributing to polarization. In addition to exocytosis, endocytosis is required to set and maintain the apical polarity of the cell. Here, we summarize some of the most recent breakthroughs in hyphal morphogenesis and apical growth in
N. crassa and the emerging questions that we believe should be addressed.
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Affiliation(s)
- Meritxell Riquelme
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, Baja California, 22860, Mexico
| | - Leonora Martínez-Núñez
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, Baja California, 22860, Mexico
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56
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Bösch K, Frantzeskakis L, Vraneš M, Kämper J, Schipper K, Göhre V. Genetic Manipulation of the Plant Pathogen Ustilago maydis to Study Fungal Biology and Plant Microbe Interactions. J Vis Exp 2016. [PMID: 27768088 DOI: 10.3791/54522] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Gene deletion plays an important role in the analysis of gene function. One of the most efficient methods to disrupt genes in a targeted manner is the replacement of the entire gene with a selectable marker via homologous recombination. During homologous recombination, exchange of DNA takes place between sequences with high similarity. Therefore, linear genomic sequences flanking a target gene can be used to specifically direct a selectable marker to the desired integration site. Blunt ends of the deletion construct activate the cell's DNA repair systems and thereby promote integration of the construct either via homologous recombination or by non-homologous-end-joining. In organisms with efficient homologous recombination, the rate of successful gene deletion can reach more than 50% making this strategy a valuable gene disruption system. The smut fungus Ustilago maydis is a eukaryotic model microorganism showing such efficient homologous recombination. Out of its about 6,900 genes, many have been functionally characterized with the help of deletion mutants, and repeated failure of gene replacement attempts points at essential function of the gene. Subsequent characterization of the gene function by tagging with fluorescent markers or mutations of predicted domains also relies on DNA exchange via homologous recombination. Here, we present the U. maydis strain generation strategy in detail using the simplest example, the gene deletion.
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Affiliation(s)
- Kristin Bösch
- Institute for Microbiology, Heinrich-Heine University Düsseldorf; Bioeconomy Science Center (BioSC)
| | | | - Miroslav Vraneš
- Department of Genetics, Institute of Applied Biosciences, Karlsruhe Institute of Technology
| | - Jörg Kämper
- Department of Genetics, Institute of Applied Biosciences, Karlsruhe Institute of Technology
| | - Kerstin Schipper
- Institute for Microbiology, Heinrich-Heine University Düsseldorf; Bioeconomy Science Center (BioSC)
| | - Vera Göhre
- Institute for Microbiology, Heinrich-Heine University Düsseldorf; Bioeconomy Science Center (BioSC); Cluster of Excellence in Plant Sciences (CEPLAS), Heinrich-Heine University Düsseldorf;
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57
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Salogiannis J, Reck-Peterson SL. Hitchhiking: A Non-Canonical Mode of Microtubule-Based Transport. Trends Cell Biol 2016; 27:141-150. [PMID: 27665063 DOI: 10.1016/j.tcb.2016.09.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/29/2016] [Accepted: 09/02/2016] [Indexed: 01/01/2023]
Abstract
The long-range movement of organelles, vesicles, and macromolecular complexes by microtubule-based transport is crucial for cell growth and survival. The canonical view of intracellular transport is that each cargo directly recruits molecular motors via cargo-specific adaptor molecules. Recently, a new paradigm called 'hitchhiking' has emerged: some cargos can achieve motility by interacting with other cargos that have already recruited molecular motors. In this way, cargos are co-transported together and their movements are directly coupled. Cargo hitchhiking was discovered in fungi. However, the observation that organelle dynamics are coupled in mammalian cells suggests that this paradigm may be evolutionarily conserved. We review here the data for hitchhiking and discuss the biological significance of this non-canonical mode of microtubule-based transport.
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Affiliation(s)
- John Salogiannis
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA; Section of Cell and Developmental Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Samara L Reck-Peterson
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA; Section of Cell and Developmental Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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58
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Sesma A. RNA metabolism and regulation of virulence programs in fungi. Semin Cell Dev Biol 2016; 57:120-127. [DOI: 10.1016/j.semcdb.2016.03.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/21/2016] [Accepted: 03/23/2016] [Indexed: 01/16/2023]
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59
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Sánchez-Elordi E, Baluška F, Echevarría C, Vicente C, Legaz ME. Defence sugarcane glycoproteins disorganize microtubules and prevent nuclear polarization and germination of Sporisorium scitamineum teliospores. JOURNAL OF PLANT PHYSIOLOGY 2016; 200:111-123. [PMID: 27372179 DOI: 10.1016/j.jplph.2016.05.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 05/17/2016] [Accepted: 05/18/2016] [Indexed: 06/06/2023]
Abstract
Microtubules (MTs) are involved in the germination of Sporisorium scitamineum teliospores. Resistant varieties of sugar cane plants produce defence glycoproteins that prevent the infection of the plants by the filamentous fungi Sporisorium scitamineum. Here, we show that a fraction of these glycoproteins prevents the correct arrangement of MTs and causes nuclear fragmentation defects. As a result, nuclei cannot correctly migrate through the growing hyphae, causing germinative failure. Arginase activity contained in defence glycoproteins is already described for preventing fungal germination. Now, its enzymatically active form is presented as a link between the defensive capacity of glycoproteins and the MT disorganization in fungal cells. Active arginase is produced in healthy and resistant plants; conversely, it is not detected in the juice from susceptible varieties, which explains why MT depolarization, nuclear disorganization as well as germination of teliospores are not significantly affected by glycoproteins from non-resistant plants. Our results also suggest that susceptible plants try to increase their levels of arginase after detecting the presence of the pathogen. However, this signal comes "too late" and such defensive mechanism fails.
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Affiliation(s)
- Elena Sánchez-Elordi
- Team of Intercellular Communication in Plant Symbiosis, Faculty of Biology, Complutense University. 12 José Antonio Novais Av., 28040 Madrid, Spain
| | - František Baluška
- Department of Plant Cell Biology, Institute of Cellular and Molecular Botany (IZMB), University Bonn. 1 Kirschallee St., D-53115 Bonn, Germany
| | - Clara Echevarría
- Team of Intercellular Communication in Plant Symbiosis, Faculty of Biology, Complutense University. 12 José Antonio Novais Av., 28040 Madrid, Spain
| | - Carlos Vicente
- Team of Intercellular Communication in Plant Symbiosis, Faculty of Biology, Complutense University. 12 José Antonio Novais Av., 28040 Madrid, Spain.
| | - M Estrella Legaz
- Team of Intercellular Communication in Plant Symbiosis, Faculty of Biology, Complutense University. 12 José Antonio Novais Av., 28040 Madrid, Spain
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60
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Abstract
Septins are highly conserved cytoskeletal proteins involved in a variety of biological processes such as cell polarization and cytokinesis. In humans, functional defects in these proteins have been linked to cancer and neuronal diseases. In recent years, substantial progress has been made in studying the structure of septin subunits and the formation of defined heteromeric building blocks. These are assembled into higher-order structures at distinct subcellular sites. An important microscopic approach in studying septin assembly and dynamics is the use of septins tagged with fluorescent proteins. This revealed, eg, that septins form rings during cytokinesis and that septins build extended filaments partially colocalizing with actin cables and microtubules. Here, we describe extensive live cell imaging of septins in the model microorganism Ustilago maydis. We present techniques to study dynamic localization of protein and septin mRNA on shuttling endosomes as well as colocalization of proteins at these highly motile units. Moreover, FLIM-FRET experiments for analyzing local protein interactions are presented. Importantly, these imaging approaches transfer well to other fungal and animal model systems for in vivo analysis of septin dynamics.
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61
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Zander S, Baumann S, Weidtkamp-Peters S, Feldbrügge M. Endosomal assembly and transport of heteromeric septin complexes promote septin cytoskeleton formation. J Cell Sci 2016; 129:2778-92. [PMID: 27252385 DOI: 10.1242/jcs.182824] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 05/26/2016] [Indexed: 02/02/2023] Open
Abstract
Septins are conserved cytoskeletal structures functioning in a variety of biological processes including cytokinesis and cell polarity. A wealth of information exists on the heterooligomeric architecture of septins and their subcellular localization at distinct sites. However, the precise mechanisms of their subcellular assembly and their intracellular transport are unknown. Here, we demonstrate that endosomal transport of septins along microtubules is crucial for formation of higher-order structures in the fungus Ustilago maydis Importantly, endosomal septin transport is dependent on each individual septin providing strong evidence that septin heteromeric complexes are assembled on endosomes. Furthermore, endosomal trafficking of all four septin mRNAs is required for endosomal localization of their translation products. Based on these results, we propose that local translation promotes the assembly of newly synthesized septins in heteromeric structures on the surface of endosomes. This is important for the long-distance transport of septins and the efficient formation of the septin cytoskeleton.
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Affiliation(s)
- Sabrina Zander
- Department of Biology, Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, 40204 Düsseldorf, Germany
| | - Sebastian Baumann
- Department of Biology, Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, 40204 Düsseldorf, Germany
| | - Stefanie Weidtkamp-Peters
- Department of Biology, Center for Advanced Imaging (CAi), Heinrich Heine University Düsseldorf, 40204 Düsseldorf, Germany
| | - Michael Feldbrügge
- Department of Biology, Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, 40204 Düsseldorf, Germany
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62
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Unfolded Protein Response (UPR) Regulator Cib1 Controls Expression of Genes Encoding Secreted Virulence Factors in Ustilago maydis. PLoS One 2016; 11:e0153861. [PMID: 27093436 PMCID: PMC4836707 DOI: 10.1371/journal.pone.0153861] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 04/05/2016] [Indexed: 11/27/2022] Open
Abstract
The unfolded protein response (UPR), a conserved eukaryotic signaling pathway to ensure protein homeostasis in the endoplasmic reticulum (ER), coordinates biotrophic development in the corn smut fungus Ustilago maydis. Exact timing of UPR activation is required for virulence and presumably connected to the elevated expression of secreted effector proteins during infection of the host plant Zea mays. In the baker’s yeast Saccharomyces cerevisiae, expression of UPR target genes is induced upon binding of the central regulator Hac1 to unfolded protein response elements (UPREs) in their promoters. While a role of the UPR in effector secretion has been described previously, we investigated a potential UPR-dependent regulation of genes encoding secreted effector proteins. In silico prediction of UPREs in promoter regions identified the previously characterized effector genes pit2 and tin1-1, as bona fide UPR target genes. Furthermore, direct binding of the Hac1-homolog Cib1 to the UPRE containing promoter fragments of both genes was confirmed by quantitative chromatin immunoprecipitation (qChIP) analysis. Targeted deletion of the UPRE abolished Cib1-dependent expression of pit2 and significantly affected virulence. Furthermore, ER stress strongly increased Pit2 expression and secretion. This study expands the role of the UPR as a signal hub in fungal virulence and illustrates, how biotrophic fungi can coordinate cellular physiology, development and regulation of secreted virulence factors.
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63
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Lozoya OA, Gilchrist CL, Guilak F. Universally Conserved Relationships between Nuclear Shape and Cytoplasmic Mechanical Properties in Human Stem Cells. Sci Rep 2016; 6:23047. [PMID: 26976044 PMCID: PMC4792134 DOI: 10.1038/srep23047] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 02/25/2016] [Indexed: 12/22/2022] Open
Abstract
The ability of cells to proliferate, differentiate, transduce extracellular signals and assemble tissues involves structural connections between nucleus and cytoskeleton. Yet, how the mechanics of these connections vary inside stem cells is not fully understood. To address those questions, we combined two-dimensional particle-tracking microrheology and morphological measures using variable reduction techniques to measure whether cytoplasmic mechanics allow for discrimination between different human adherent stem cell types and across different culture conditions. Here we show that nuclear shape is a quantifiable discriminant of mechanical properties in the perinuclear cytoskeleton (pnCSK) of various stem cell types. Also, we find the pnCSK is a region with different mechanical properties than elsewhere in the cytoskeleton, with heterogeneously distributed locations exhibiting subdiffusive features, and which obeys physical relations conserved among various stem cell types. Finally, we offer a prospective basis to discriminate between stem cell types by coupling perinuclear mechanical properties to nuclear shape.
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Affiliation(s)
- Oswaldo A Lozoya
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | | | - Farshid Guilak
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.,Departments of Orthopaedic Surgery, Biomedical Engineering, and Developmental Biology, Washington University in St. Louis, St. Louis, MO 63110, USA.,Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA
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64
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Kilaru S, Schuster M, Latz M, Guo M, Steinberg G. Fluorescent markers of the endocytic pathway in Zymoseptoria tritici. Fungal Genet Biol 2016; 79:150-7. [PMID: 26092801 PMCID: PMC4502447 DOI: 10.1016/j.fgb.2015.03.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/12/2015] [Accepted: 03/17/2015] [Indexed: 12/28/2022]
Abstract
We establish Z. tritici fimbrin (ZtFim1) and small GTPases (ZtRab5, ZtRab7) as endocytic markers. All markers localize correctly, proven by live cell imaging and co-staining and pharmaceutical studies. We provide 3 carboxin-resistance conveying vectors for integration of all markers into the sdi1 locus. We provide 3 hygromycin B-resistance conveying vectors for random integration of all markers.
Hyphal growth in filamentous fungi is supported by the uptake (endocytosis) and recycling of membranes and associated proteins at the growing tip. An increasing body of published evidence in various fungi demonstrates that this process is of essential importance for fungal growth and pathogenicity. Here, we introduce fluorescent markers to visualize the endocytic pathway in the wheat pathogen Zymoseptoria tritici. We fused enhanced green-fluorescent protein (eGFP) to the actin-binding protein fimbrin (ZtFim1), which is located in actin patches that are formed at the plasma membrane and are participating in endocytic uptake at the cell surface. In addition, we tagged early endosomes by eGFP-labelling a Rab5-homologue (ZtRab5) and late endosomes and vacuoles by expressing eGFP-Rab7 homologue (ZtRab7). Using fluorescent dyes and live cell imaging we confirmed the dynamic behavior and localization of these markers. This set of molecular tools enables an in-depth phenotypic analysis of Z. tritici mutant strains thereby supporting new strategies towards the goal of controlling wheat against Z. tritici.
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Affiliation(s)
- S Kilaru
- Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - M Schuster
- Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - M Latz
- Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - M Guo
- Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - G Steinberg
- Biosciences, University of Exeter, Exeter EX4 4QD, UK.
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65
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Salogiannis J, Egan MJ, Reck-Peterson SL. Peroxisomes move by hitchhiking on early endosomes using the novel linker protein PxdA. J Cell Biol 2016; 212:289-96. [PMID: 26811422 PMCID: PMC4748578 DOI: 10.1083/jcb.201512020] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 01/05/2016] [Indexed: 11/22/2022] Open
Abstract
Eukaryotic cells use microtubule-based intracellular transport for the delivery of many subcellular cargos, including organelles. The canonical view of organelle transport is that organelles directly recruit molecular motors via cargo-specific adaptors. In contrast with this view, we show here that peroxisomes move by hitchhiking on early endosomes, an organelle that directly recruits the transport machinery. Using the filamentous fungus Aspergillus nidulans we found that hitchhiking is mediated by a novel endosome-associated linker protein, PxdA. PxdA is required for normal distribution and long-range movement of peroxisomes, but not early endosomes or nuclei. Using simultaneous time-lapse imaging, we find that early endosome-associated PxdA localizes to the leading edge of moving peroxisomes. We identify a coiled-coil region within PxdA that is necessary and sufficient for early endosome localization and peroxisome distribution and motility. These results present a new mechanism of microtubule-based organelle transport in which peroxisomes hitchhike on early endosomes and identify PxdA as the novel linker protein required for this coupling.
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Affiliation(s)
- John Salogiannis
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Martin J Egan
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Samara L Reck-Peterson
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115 Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093 Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
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66
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Sarkari P, Feldbrügge M, Schipper K. The Corn Smut Fungus Ustilago maydis as an Alternative Expression System for Biopharmaceuticals. Fungal Biol 2016. [DOI: 10.1007/978-3-319-27951-0_7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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67
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Guimaraes SC, Schuster M, Bielska E, Dagdas G, Kilaru S, Meadows BRA, Schrader M, Steinberg G. Peroxisomes, lipid droplets, and endoplasmic reticulum "hitchhike" on motile early endosomes. J Cell Biol 2015; 211:945-54. [PMID: 26620910 PMCID: PMC4674278 DOI: 10.1083/jcb.201505086] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 10/26/2015] [Indexed: 02/04/2023] Open
Abstract
Intracellular transport is mediated by molecular motors that bind cargo to be transported along the cytoskeleton. Here, we report, for the first time, that peroxisomes (POs), lipid droplets (LDs), and the endoplasmic reticulum (ER) rely on early endosomes (EEs) for intracellular movement in a fungal model system. We show that POs undergo kinesin-3- and dynein-dependent transport along microtubules. Surprisingly, kinesin-3 does not colocalize with POs. Instead, the motor moves EEs that drag the POs through the cell. PO motility is abolished when EE motility is blocked in various mutants. Most LD and ER motility also depends on EE motility, whereas mitochondria move independently of EEs. Covisualization studies show that EE-mediated ER motility is not required for PO or LD movement, suggesting that the organelles interact with EEs independently. In the absence of EE motility, POs and LDs cluster at the growing tip, whereas ER is partially retracted to subapical regions. Collectively, our results show that moving EEs interact transiently with other organelles, thereby mediating their directed transport and distribution in the cell.
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Affiliation(s)
| | - Martin Schuster
- Biosciences, University of Exeter, Exeter EX4 4QD, England, UK
| | - Ewa Bielska
- Biosciences, University of Exeter, Exeter EX4 4QD, England, UK
| | - Gulay Dagdas
- Biosciences, University of Exeter, Exeter EX4 4QD, England, UK
| | - Sreedhar Kilaru
- Biosciences, University of Exeter, Exeter EX4 4QD, England, UK
| | - Ben R A Meadows
- Biosciences, University of Exeter, Exeter EX4 4QD, England, UK
| | | | - Gero Steinberg
- Biosciences, University of Exeter, Exeter EX4 4QD, England, UK
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68
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Momany M. Rite of passage: a bZIP transcription factor must transit the cell apex to become competent. Mol Microbiol 2015; 98:605-6. [PMID: 26387769 DOI: 10.1111/mmi.13224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2015] [Indexed: 11/30/2022]
Abstract
In the filamentous fungus Aspergillus nidulans BrlA triggers the central developmental pathway that controls the transition from vegetative growth to asexual reproduction. Upstream regulators including the bZIP transcription factor FlbB activate the expression of brlA. Previous work has established that FlbB localizes to both the apex of the hypha, where it interacts with and is anchored by FlbE, and to nuclei, with highest levels in the nucleus closest to the apex and successively lower levels in nuclei further away from the apex. In this issue, Herrero-Garcia et al. dissect the roles of these two FlbB pools and the mechanisms underlying their localization and activity. Using a photoactivatable tag, they demonstrate that FlbB moves from the tip into the apical nucleus. Through a series of deletion constructs, they show that import of FlbB into the nucleus requires a bipartite NLS, that FlbB localization at the tip requires actin and that the FlbB tip-high gradient appears to be mass action dependent as the gradient is lost with FlbB constitutive upregulation. They show that while the pool of FlbB at the apex is required for triggering asexual development, the tip high nuclear gradient is not required.
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Affiliation(s)
- Michelle Momany
- Department of Plant Biology, University of Georgia, Athens, GA, USA
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69
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Abstract
Intracellular logistics are essential for delivery of newly synthesized material during polar growth of fungal hyphae. Proteins and lipids are actively transported throughout the cell by motor-dependent movement of small vesicles or larger units such as endosomes and the endoplasmic reticulum. A remarkably tight link is emerging between active membrane trafficking and mRNA transport, a process that determines the precise subcellular localization of translation products within the cell. Here, we report on recent insights into the mechanism and biological role of these intricate cotransport processes in fungal models such as Saccharomyces cerevisiae, Candida albicans, and Ustilago maydis. In the latter, we focus on the new finding of endosomal mRNA transport and its implications for protein targeting, complex assembly, and septin biology.
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Affiliation(s)
- Carl Haag
- Cluster of Excellence on Plant Sciences, Institute for Microbiology, Heinrich Heine University Düsseldorf, 40204 Düsseldorf, Germany; , ,
| | - Benedikt Steuten
- Cluster of Excellence on Plant Sciences, Institute for Microbiology, Heinrich Heine University Düsseldorf, 40204 Düsseldorf, Germany; , ,
| | - Michael Feldbrügge
- Cluster of Excellence on Plant Sciences, Institute for Microbiology, Heinrich Heine University Düsseldorf, 40204 Düsseldorf, Germany; , ,
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70
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Experimental approaches to investigate effector translocation into host cells in the Ustilago maydis/maize pathosystem. Eur J Cell Biol 2015; 94:349-58. [PMID: 26118724 DOI: 10.1016/j.ejcb.2015.06.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The fungus Ustilago maydis is a pathogen that establishes a biotrophic interaction with Zea mays. The interaction with the plant host is largely governed by more than 300 novel, secreted protein effectors, of which only four have been functionally characterized. Prerequisite to examine effector function is to know where effectors reside after secretion. Effectors can remain in the extracellular space, i.e. the plant apoplast (apoplastic effectors), or can cross the plant plasma membrane and exert their function inside the host cell (cytoplasmic effectors). The U. maydis effectors lack conserved motifs in their primary sequences that could allow a classification of the effectome into apoplastic/cytoplasmic effectors. This represents a significant obstacle in functional effector characterization. Here we describe our attempts to establish a system for effector classification into apoplastic and cytoplasmic members, using U. maydis for effector delivery.
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71
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Xiang X, Qiu R, Yao X, Arst HN, Peñalva MA, Zhang J. Cytoplasmic dynein and early endosome transport. Cell Mol Life Sci 2015; 72:3267-80. [PMID: 26001903 DOI: 10.1007/s00018-015-1926-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 05/04/2015] [Accepted: 05/05/2015] [Indexed: 11/25/2022]
Abstract
Microtubule-based distribution of organelles/vesicles is crucial for the function of many types of eukaryotic cells and the molecular motor cytoplasmic dynein is required for transporting a variety of cellular cargos toward the microtubule minus ends. Early endosomes represent a major cargo of dynein in filamentous fungi, and dynein regulators such as LIS1 and the dynactin complex are both required for early endosome movement. In fungal hyphae, kinesin-3 and dynein drive bi-directional movements of early endosomes. Dynein accumulates at microtubule plus ends; this accumulation depends on kinesin-1 and dynactin, and it is important for early endosome movements towards the microtubule minus ends. The physical interaction between dynein and early endosome requires the dynactin complex, and in particular, its p25 component. The FTS-Hook-FHIP (FHF) complex links dynein-dynactin to early endosomes, and within the FHF complex, Hook interacts with dynein-dynactin, and Hook-early endosome interaction depends on FHIP and FTS.
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Affiliation(s)
- Xin Xiang
- Department of Biochemistry and Molecular Biology, F. Edward Hébert School of Medicine, The Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA,
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72
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Pohlmann T, Baumann S, Haag C, Albrecht M, Feldbrügge M. A FYVE zinc finger domain protein specifically links mRNA transport to endosome trafficking. eLife 2015; 4. [PMID: 25985087 PMCID: PMC4466420 DOI: 10.7554/elife.06041] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 05/15/2015] [Indexed: 12/20/2022] Open
Abstract
An emerging theme in cellular logistics is the close connection between mRNA and membrane trafficking. A prominent example is the microtubule-dependent transport of mRNAs and associated ribosomes on endosomes. This coordinated process is crucial for correct septin filamentation and efficient growth of polarised cells, such as fungal hyphae. Despite detailed knowledge on the key RNA-binding protein and the molecular motors involved, it is unclear how mRNAs are connected to membranes during transport. Here, we identify a novel factor containing a FYVE zinc finger domain for interaction with endosomal lipids and a new PAM2-like domain required for interaction with the MLLE domain of the key RNA-binding protein. Consistently, loss of this FYVE domain protein leads to specific defects in mRNA, ribosome, and septin transport without affecting general functions of endosomes or their movement. Hence, this is the first endosomal component specific for mRNP trafficking uncovering a new mechanism to couple mRNPs to endosomes. DOI:http://dx.doi.org/10.7554/eLife.06041.001 DNA contains the instructions to build proteins. These instructions are first copied to make a molecule of messenger RNA (or mRNA for short). A large machine called the ribosome then reads the mRNA molecule and translates it to build a protein. Many proteins must get to particular locations in a cell to carry out their roles. For some proteins, this is achieved by transporting the mRNAs to the right location before they get translated, via a process called ‘mRNA trafficking’. However, mRNAs do not move by themselves; instead they bind to a host of mRNA-binding proteins, and the ribosomes that are required for translation to take place. Cells also move proteins between different locations using small bubble-like structures called vesicles. These vesicles are surrounded by a membrane, and so this process is known as ‘membrane trafficking’. Previous work has shown that these two processes are often linked, as vesicles can also carry mRNA molecules. But it is not fully understood how mRNA molecules are connected to vesicles. Now, Pohlmann et al. have used a fungus called Ustilago maydis as a model system to investigate how mRNAs and vesicles can move together in cells that grow to form filament-like structures called hyphae. This fungus uses these filaments to penetrate into plant tissues and causes a disease called corn smut. The experiments revealed a vesicle protein called Upa1 that contains a new type of binding site that allows Upa1 to bring an important RNA-binding protein to the surface of vesicles. Since the RNA-binding protein binds mRNA and the translating ribosomes, this can explain how mRNAs can associate with membranes to move together along hyphae. When Pohlmann et al. engineered fungi that lacked the gene for Upa1, these mutants had problems transporting their mRNAs and associated ribosomes. These findings reveal a direct connection between mRNA trafficking and membrane trafficking. Future studies could now investigate whether similar processes take place in other cells that grow as long filaments, such as plant pollen tubes or nerve cells. These studies might provide new insights into plant reproduction or brain activity. DOI:http://dx.doi.org/10.7554/eLife.06041.002
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Affiliation(s)
- Thomas Pohlmann
- Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Sebastian Baumann
- Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Carl Haag
- Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Mario Albrecht
- Max Planck Institute for Informatics, Saarbrücken, Germany
| | - Michael Feldbrügge
- Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
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73
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Takeshita N, Wernet V, Tsuizaki M, Grün N, Hoshi HO, Ohta A, Fischer R, Horiuchi H. Transportation of Aspergillus nidulans Class III and V Chitin Synthases to the Hyphal Tips Depends on Conventional Kinesin. PLoS One 2015; 10:e0125937. [PMID: 25955346 PMCID: PMC4425547 DOI: 10.1371/journal.pone.0125937] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/21/2015] [Indexed: 12/02/2022] Open
Abstract
Cell wall formation and maintenance are crucial for hyphal morphogenesis. In many filamentous fungi, chitin is one of the main structural components of the cell wall. Aspergillus nidulans ChsB, a chitin synthase, and CsmA, a chitin synthase with a myosin motor-like domain (MMD) at its N-terminus, both localize predominantly at the hyphal tip regions and at forming septa. ChsB and CsmA play crucial roles in polarized hyphal growth in A. nidulans. In this study, we investigated the mechanism by which CsmA and ChsB accumulate at the hyphal tip in living hyphae. Deletion of kinA, a gene encoding conventional kinesin (kinesin-1), impaired the localization of GFP-CsmA and GFP-ChsB at the hyphal tips. The transport frequency of GFP-CsmA and GFP-ChsB in both anterograde and retrograde direction appeared lower in the kinA-deletion strain compared to wild type, although the velocities of the movements were comparable. Co-localization of GFP-ChsB and GFP-CsmA with mRFP1-KinArigor, a KinA mutant that binds to microtubules but does not move along them, was observed in the posterior of the hyphal tip regions. KinA co-immunoprecipitated with ChsB and CsmA. Co-localization and association of CsmA with KinA did not depend on the MMD. These findings indicate that ChsB and CsmA are transported along microtubules to the subapical region by KinA.
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Affiliation(s)
- Norio Takeshita
- Department of Microbiology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Valentin Wernet
- Department of Microbiology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Makusu Tsuizaki
- Department of Biotechnology, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Nathalie Grün
- Department of Microbiology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Hiro-omi Hoshi
- Department of Biotechnology, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Akinori Ohta
- Department of Biotechnology, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Reinhard Fischer
- Department of Microbiology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Hiroyuki Horiuchi
- Department of Biotechnology, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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74
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Higuchi Y, Steinberg G. Early endosomes motility in filamentous fungi: How and why they move. FUNGAL BIOL REV 2015. [DOI: 10.1016/j.fbr.2015.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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75
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Chitinases Are Essential for Cell Separation in Ustilago maydis. EUKARYOTIC CELL 2015; 14:846-57. [PMID: 25934689 DOI: 10.1128/ec.00022-15] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 04/24/2015] [Indexed: 02/07/2023]
Abstract
Chitin is an essential component of the fungal cell wall, providing rigidity and stability. Its degradation is mediated by chitinases and supposedly ensures the dynamic plasticity of the cell wall during growth and morphogenesis. Hence, chitinases should be particularly important for fungi with dramatic morphological changes, such as Ustilago maydis. This smut fungus switches from yeast to filamentous growth for plant infection, proliferates as a mycelium in planta, and forms teliospores for spreading. Here, we investigate the contribution of its four chitinolytic enzymes to the different morphological changes during the complete life cycle in a comprehensive study of deletion strains combined with biochemical and cell biological approaches. Interestingly, two chitinases act redundantly in cell separation during yeast growth. They mediate the degradation of remnant chitin in the fragmentation zone between mother and daughter cell. In contrast, even the complete lack of chitinolytic activity does not affect formation of the infectious filament, infection, biotrophic growth, or teliospore germination. Thus, unexpectedly we can exclude a major role for chitinolytic enzymes in morphogenesis or pathogenicity of U. maydis. Nevertheless, redundant activity of even two chitinases is essential for cell separation during saprophytic growth, possibly to improve nutrient access or spreading of yeast cells by wind or rain.
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76
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Schuster M, Kilaru S, Latz M, Steinberg G. Fluorescent markers of the microtubule cytoskeleton in Zymoseptoria tritici. Fungal Genet Biol 2015; 79:141-9. [PMID: 25857261 PMCID: PMC4502552 DOI: 10.1016/j.fgb.2015.03.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/12/2015] [Accepted: 03/17/2015] [Indexed: 11/28/2022]
Abstract
The microtubule cytoskeleton supports vital processes in fungal cells, including hyphal growth and mitosis. Consequently, it is a target for fungicides, such as benomyl. The use of fluorescent fusion proteins to illuminate microtubules and microtubule-associated proteins has led to a break-through in our understanding of their dynamics and function in fungal cells. Here, we introduce fluorescent markers to visualize microtubules and accessory proteins in the wheat pathogen Zymoseptoria tritici. We fused enhanced green-fluorescent protein to α-tubulin (ZtTub2), to ZtPeb1, a homologue of the mammalian plus-end binding protein EB1, and to ZtGrc1, a component of the minus-end located γ-tubulin ring complex, involved in the nucleation of microtubules. In vivo observation confirms the localization and dynamic behaviour of all three markers. These marker proteins are useful tools for understanding the organization and importance of the microtubule cytoskeleton in Z. tritici.
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Affiliation(s)
- M Schuster
- Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - S Kilaru
- Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - M Latz
- Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - G Steinberg
- Biosciences, University of Exeter, Exeter EX4 4QD, UK.
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77
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Abstract
Endosomes are multipurpose membranous carriers important for endocytosis and secretion. During membrane trafficking, endosomes transport lipids, proteins, and even RNAs. In highly polarized cells such as fungal hyphae, they shuttle bidirectionally along microtubules mediated by molecular motors like kinesins and dynein. For in vivo studies of these highly dynamic protein/membrane complexes, advanced fluorescence microscopy is instrumental. In this chapter, we describe live cell imaging of endosomes in two distantly related fungal model systems, the basidiomycete Ustilago maydis and the ascomycete Aspergillus nidulans. We provide insights into live cell imaging of dynamic endosomal proteins and RNA, dual-color detection for colocalization studies, as well as fluorescence recovery after photobleaching (FRAP) for quantification and photo-activated localization microscopy (PALM) for super-resolution. These methods described in two well-studied fungal model systems are applicable to a broad range of other organisms.
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78
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Holstein JM, Stummer D, Rentmeister A. Enzymatic modification of 5'-capped RNA with a 4-vinylbenzyl group provides a platform for photoclick and inverse electron-demand Diels-Alder reaction. Chem Sci 2014; 6:1362-1369. [PMID: 29560223 PMCID: PMC5811123 DOI: 10.1039/c4sc03182b] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 11/26/2014] [Indexed: 01/20/2023] Open
Abstract
Enzymatic transfer of 4-vinylbenzyl to the mRNA 5′-cap gives access to the fluorogenic photoclick and the inverse electron-demand Diels–Alder reaction.
Chemo-enzymatic strategies provide a highly selective means to label different classes of biomolecules in vitro, but also in vivo. In the field of RNA, efficient labeling of eukaryotic mRNA with small organic reporter molecules would provide a way to detect endogenous mRNA and is therefore highly attractive. Although more and more bioorthogonal reactions are being reported, they can only be applied to chemo-enzymatic strategies if a suitable (i.e., click compatible) modification can be introduced into the RNA of interest. We report enzymatic site-specific transfer of a 4-vinylbenzyl group to the 5′-cap typical of eukaryotic mRNAs. The 4-vinylbenzyl group gives access to mRNA labeling using the inverse electron-demand Diels–Alder reaction, which does not work with an enzymatically transferred allyl group. The 4-vinylbenzyl-modified 5′-cap can also be converted in a photoclick reaction generating a “turn-on” fluorophore. Both click reactions are bioorthogonal and the two step approach also works in eukaryotic cell lysate. Enzymatic transfer of the 4-vinylbenzyl group addresses the lack of flexibility often attributed to biotransformations and thus advances the potential of chemo-enzymatic approaches for labeling.
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Affiliation(s)
- Josephin Marie Holstein
- Westfälische Wilhelms-Universität Münster , Institute of Biochemistry , 48149 Muenster , Germany .
| | - Daniela Stummer
- Westfälische Wilhelms-Universität Münster , Institute of Biochemistry , 48149 Muenster , Germany . .,Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM) , University of Muenster , 48149 Muenster , Germany
| | - Andrea Rentmeister
- Westfälische Wilhelms-Universität Münster , Institute of Biochemistry , 48149 Muenster , Germany . .,Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM) , University of Muenster , 48149 Muenster , Germany
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79
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Vollmeister E, Schipper K, Feldbrügge M. Microtubule-dependent mRNA transport in the model microorganismUstilago maydis. RNA Biol 2014; 9:261-8. [DOI: 10.4161/rna.19432] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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80
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Caballero-Lima D, Hautbergue GM, Wilson SA, Sudbery PE. In Candida albicans hyphae, Sec2p is physically associated with SEC2 mRNA on secretory vesicles. Mol Microbiol 2014; 94:828-42. [PMID: 25231350 PMCID: PMC4278529 DOI: 10.1111/mmi.12799] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2014] [Indexed: 01/05/2023]
Abstract
Candida albicans hyphae grow in a highly polarized fashion from their tips. This polarized growth requires the continuous delivery of secretory vesicles to the tip region. Vesicle delivery depends on Sec2p, the Guanine Exchange Factor (GEF) for the Rab GTPase Sec4p. GTP bound Sec4p is required for the transit of secretory vesicles from the trans-Golgi to sites of polarized growth. We previously showed that phosphorylation of Sec2p at residue S584 was necessary for Sec2p to support hyphal, but not yeast growth. Here we show that on secretory vesicles SEC2 mRNA is physically associated with Sec2p. Moreover, we show that the phosphorylation of S584 allows SEC2 mRNA to dissociate from Sec2p and we speculate that this is necessary for Sec2p function and/or translation. During hyphal extension, the growing tip may be separated from the nucleus by up to 15 μm. Transport of SEC2 mRNA on secretory vesicles to the tip localizes SEC2 translation to tip allowing a sufficient accumulation of this key protein at the site of polarized growth.
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Affiliation(s)
- David Caballero-Lima
- Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
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81
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Pöhlmann J, Risse C, Seidel C, Pohlmann T, Jakopec V, Walla E, Ramrath P, Takeshita N, Baumann S, Feldbrügge M, Fischer R, Fleig U. The Vip1 inositol polyphosphate kinase family regulates polarized growth and modulates the microtubule cytoskeleton in fungi. PLoS Genet 2014; 10:e1004586. [PMID: 25254656 PMCID: PMC4177672 DOI: 10.1371/journal.pgen.1004586] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 07/08/2014] [Indexed: 11/19/2022] Open
Abstract
Microtubules (MTs) are pivotal for numerous eukaryotic processes ranging from cellular morphogenesis, chromosome segregation to intracellular transport. Execution of these tasks requires intricate regulation of MT dynamics. Here, we identify a new regulator of the Schizosaccharomyces pombe MT cytoskeleton: Asp1, a member of the highly conserved Vip1 inositol polyphosphate kinase family. Inositol pyrophosphates generated by Asp1 modulate MT dynamic parameters independent of the central +TIP EB1 and in a dose-dependent and cellular-context-dependent manner. Importantly, our analysis of the in vitro kinase activities of various S. pombe Asp1 variants demonstrated that the C-terminal phosphatase-like domain of the dual domain Vip1 protein negatively affects the inositol pyrophosphate output of the N-terminal kinase domain. These data suggest that the former domain has phosphatase activity. Remarkably, Vip1 regulation of the MT cytoskeleton is a conserved feature, as Vip1-like proteins of the filamentous ascomycete Aspergillus nidulans and the distantly related pathogenic basidiomycete Ustilago maydis also affect the MT cytoskeleton in these organisms. Consistent with the role of interphase MTs in growth zone selection/maintenance, all 3 fungal systems show aspects of aberrant cell morphogenesis. Thus, for the first time we have identified a conserved biological process for inositol pyrophosphates.
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Affiliation(s)
- Jennifer Pöhlmann
- Lehrstuhl für funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Carmen Risse
- Lehrstuhl für funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Constanze Seidel
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Karlsruhe, Germany
| | - Thomas Pohlmann
- Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Visnja Jakopec
- Lehrstuhl für funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Eva Walla
- Lehrstuhl für funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Pascal Ramrath
- Lehrstuhl für funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Norio Takeshita
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Karlsruhe, Germany
- University of Tsukuba, Faculty of Life and Environmental Sciences, Ibaraki, Tsukuba, Japan
| | - Sebastian Baumann
- Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Michael Feldbrügge
- Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Reinhard Fischer
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Karlsruhe, Germany
| | - Ursula Fleig
- Lehrstuhl für funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
- * E-mail:
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82
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mRNA transport meets membrane traffic. Trends Genet 2014; 30:408-17. [DOI: 10.1016/j.tig.2014.07.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 07/09/2014] [Accepted: 07/09/2014] [Indexed: 02/07/2023]
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83
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Czaplinski K. Understanding mRNA trafficking: Are we there yet? Semin Cell Dev Biol 2014; 32:63-70. [DOI: 10.1016/j.semcdb.2014.04.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 04/17/2014] [Indexed: 10/25/2022]
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84
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Baptista FI, Pinto MJ, Elvas F, Martins T, Almeida RD, Ambrósio AF. Diabetes induces changes in KIF1A, KIF5B and dynein distribution in the rat retina: implications for axonal transport. Exp Eye Res 2014; 127:91-103. [PMID: 25064602 DOI: 10.1016/j.exer.2014.07.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 07/14/2014] [Accepted: 07/15/2014] [Indexed: 10/25/2022]
Abstract
Diabetic retinopathy is a leading cause of vision loss and blindness. Disruption of axonal transport is associated with many neurodegenerative diseases and might also play a role in diabetes-associated disorders affecting nervous system. We investigated the impact of type 1 diabetes (2 and 8 weeks duration) on KIF1A, KIF5B and dynein motor proteins in the retina. Additionally, since hyperglycemia is considered the main trigger of diabetic complications, we investigated whether prolonged exposure to elevated glucose could affect the content and distribution of motor proteins in retinal cultures. The immunoreactivity of motor proteins was evaluated by immunohistochemistry in retinal sections and by immunoblotting in total retinal extracts from streptozotocin-induced diabetic and age-matched control animals. Primary retinal cultures were exposed to high glucose (30 mM) or mannitol (osmotic control; 24.5 mM plus 5.5 mM glucose), for seven days. Diabetes decreased the content of KIF1A at 8 weeks of diabetes as well as KIF1A immunoreactivity in the majority of retinal layers, except for the photoreceptor and outer nuclear layer. Changes in KIF5B immunoreactivity were also detected by immunohistochemistry in the retina at 8 weeks of diabetes, being increased at the photoreceptor and outer nuclear layer, and decreased in the ganglion cell layer. Regarding dynein immunoreactivity there was an increase in the ganglion cell layer after 8 weeks of diabetes. No changes were detected in retinal cultures. These alterations suggest that axonal transport may be impaired under diabetes, which might contribute to early signs of neural dysfunction in the retina of diabetic patients and animal models.
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Affiliation(s)
- Filipa I Baptista
- Centre of Ophthalmology and Vision Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal; Pharmacology and Experimental Therapeutics, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal
| | - Maria J Pinto
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal; PhD Programme in Experimental Biology and Biomedicine (PDBEB), Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Filipe Elvas
- Centre of Ophthalmology and Vision Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal; Pharmacology and Experimental Therapeutics, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal
| | - Tiago Martins
- Centre of Ophthalmology and Vision Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal; Pharmacology and Experimental Therapeutics, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal
| | - Ramiro D Almeida
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - António F Ambrósio
- Centre of Ophthalmology and Vision Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal; Pharmacology and Experimental Therapeutics, IBILI, Faculty of Medicine, University of Coimbra, 3004-548 Coimbra, Portugal; CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal; AIBILI, 3004-548 Coimbra, Portugal.
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85
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Lanver D, Berndt P, Tollot M, Naik V, Vranes M, Warmann T, Münch K, Rössel N, Kahmann R. Plant surface cues prime Ustilago maydis for biotrophic development. PLoS Pathog 2014; 10:e1004272. [PMID: 25033195 PMCID: PMC4102580 DOI: 10.1371/journal.ppat.1004272] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 06/12/2014] [Indexed: 11/19/2022] Open
Abstract
Infection-related development of phytopathogenic fungi is initiated by sensing and responding to plant surface cues. This response can result in the formation of specialized infection structures, so-called appressoria. To unravel the program inducing filaments and appressoria in the biotrophic smut fungus Ustilago maydis, we exposed cells to a hydrophobic surface and the cutin monomer 16-hydroxy hexadecanoic acid. Genome-wide transcriptional profiling at the pre-penetration stage documented dramatic transcriptional changes in almost 20% of the genes. Comparisons with the U. maydis sho1 msb2 double mutant, lacking two putative sensors for plant surface cues, revealed that these plasma membrane receptors regulate a small subset of the surface cue-induced genes comprising mainly secreted proteins including potential plant cell wall degrading enzymes. Targeted gene deletion analysis ascribed a role to up-regulated GH51 and GH62 arabinofuranosidases during plant penetration. Among the sho1/msb2-dependently expressed genes were several secreted effectors that are essential for virulence. Our data also demonstrate specific effects on two transcription factors that redirect the transcriptional regulatory network towards appressorium formation and plant penetration. This shows that plant surface cues prime U. maydis for biotrophic development. A basic requirement for pathogens to infect their hosts and to cause disease is to detect that they are in contact with the host surface. Plant pathogenic fungi typically respond to leaf surface contact with the development of specialized infection structures enabling the fungus to penetrate the leaf cuticle and to enter the plant tissue. In this study we analyzed the response of the corn smut fungus Ustilago maydis to two plant surface cues, such as hydrophobic surface and cutin monomers. Based on genome-wide gene expression analysis we found that these cues trigger the production of secreted plant cell wall degrading enzymes helping the fungus to penetrate the plant surface. In addition, genes were activated that code for a group of secreted proteins, so-called effectors, that affect virulence after penetration. These results demonstrate that plant surface cues trigger fungal penetration of the plant surface and also prime the fungus for later development inside plant tissue. These specific responses required two cell surface proteins that likely function as plant surface sensors.
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Affiliation(s)
- Daniel Lanver
- Max Planck Institute for Terrestrial Microbiology, Department of Organismic Interactions, Marburg, Germany
| | - Patrick Berndt
- Max Planck Institute for Terrestrial Microbiology, Department of Organismic Interactions, Marburg, Germany
| | - Marie Tollot
- Max Planck Institute for Terrestrial Microbiology, Department of Organismic Interactions, Marburg, Germany
| | - Vikram Naik
- Max Planck Institute for Terrestrial Microbiology, Department of Organismic Interactions, Marburg, Germany
| | - Miroslav Vranes
- Karlsruhe Institute of Technology (KIT), Institute for Applied Biosciences, Department of Genetics, Karlsruhe, Germany
| | - Tobias Warmann
- Max Planck Institute for Terrestrial Microbiology, Department of Organismic Interactions, Marburg, Germany
| | - Karin Münch
- Max Planck Institute for Terrestrial Microbiology, Department of Organismic Interactions, Marburg, Germany
| | - Nicole Rössel
- Max Planck Institute for Terrestrial Microbiology, Department of Organismic Interactions, Marburg, Germany
| | - Regine Kahmann
- Max Planck Institute for Terrestrial Microbiology, Department of Organismic Interactions, Marburg, Germany
- * E-mail:
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86
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Steinberg G. Endocytosis and early endosome motility in filamentous fungi. Curr Opin Microbiol 2014; 20:10-8. [PMID: 24835422 PMCID: PMC4148197 DOI: 10.1016/j.mib.2014.04.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Accepted: 04/21/2014] [Indexed: 10/25/2022]
Abstract
Hyphal growth of filamentous fungi requires microtubule-based long-distance motility of early endosomes. Since the discovery of this process in Ustilago maydis, our understanding of its molecular basis and biological function has greatly advanced. Studies in U. maydis and Aspergillus nidulans reveal a complex interplay of the motor proteins kinesin-3 and dynein, which co-operate to support bi-directional motion of early endosomes. Genetic screening has shed light on the molecular mechanisms underpinning motor regulation, revealing Hook protein as general motor adapters on early endosomes. Recently, fascinating insight into unexpected roles for endosome motility has emerged. This includes septin filament formation and cellular distribution of the machinery for protein translation.
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Affiliation(s)
- Gero Steinberg
- Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
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87
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Granger E, McNee G, Allan V, Woodman P. The role of the cytoskeleton and molecular motors in endosomal dynamics. Semin Cell Dev Biol 2014; 31:20-9. [PMID: 24727350 PMCID: PMC4071412 DOI: 10.1016/j.semcdb.2014.04.011] [Citation(s) in RCA: 176] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/01/2014] [Accepted: 04/03/2014] [Indexed: 12/28/2022]
Abstract
The endocytic pathway is essential for processes that define how cells interact with their environment, including receptor signalling, cell adhesion and migration, pathogen entry, membrane protein turnover and nutrient uptake. The spatial organisation of endocytic trafficking requires motor proteins that tether membranes or transport them along the actin and microtubule cytoskeletons. Microtubules, actin filaments and motor proteins also provide force to deform and assist in the scission of membranes, thereby facilitating endosomal sorting and the generation of transport intermediates.
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Affiliation(s)
- Elizabeth Granger
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Gavin McNee
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Victoria Allan
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK.
| | - Philip Woodman
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK.
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88
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Higuchi Y, Ashwin P, Roger Y, Steinberg G. Early endosome motility spatially organizes polysome distribution. ACTA ACUST UNITED AC 2014; 204:343-57. [PMID: 24493587 PMCID: PMC3912533 DOI: 10.1083/jcb.201307164] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To distribute the protein translation machinery throughout the cytoplasm, polysomes in the fungus Ustilago maydis associate with mobile early endosomes, resulting in long-range motility along microtubules. Early endosomes (EEs) mediate protein sorting, and their cytoskeleton-dependent motility supports long-distance signaling in neurons. Here, we report an unexpected role of EE motility in distributing the translation machinery in a fungal model system. We visualize ribosomal subunit proteins and show that the large subunits diffused slowly throughout the cytoplasm (Dc,60S = 0.311 µm2/s), whereas entire polysomes underwent long-range motility along microtubules. This movement was mediated by “hitchhiking” on kinesin-3 and dynein-driven EEs, where the polysomes appeared to translate EE-associated mRNA into proteins. Modeling indicates that this motor-driven transport is required for even cellular distribution of newly formed ribosomes. Indeed, impaired EE motility in motor mutants, or their inability to bind EEs in mutants lacking the RNA-binding protein Rrm4, reduced ribosome transport and induced ribosome aggregation near the nucleus. As a consequence, cell growth was severely restricted. Collectively, our results indicate that polysomes associate with moving EEs and that “off- and reloading” distributes the protein translation machinery.
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Affiliation(s)
- Yujiro Higuchi
- Biosciences and 2 Mathematics Research Institute, University of Exeter, Exeter EX4 4QD, England, UK
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89
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Abstract
After export from the nucleus, ribosomes need to be distributed throughout the entire cell so that protein synthesis can occur even at distant sites. In the elongated hyphal cell of the fungus Ustilago maydis, Higuchi et al. (2014. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201307164) now demonstrate that polysomes associate with early endosomes that undergo kinesin 3- and dynein-dependent long-range motility. The bidirectional movement of early endosomes randomly distributes polysomes, which may ensure the even distribution of the translation machinery across the entire cell.
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Affiliation(s)
- Isabel M Palacios
- Zoology Department, University of Cambridge, Cambridge CB2 3EJ, England, UK
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90
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The SPF27 homologue Num1 connects splicing and kinesin 1-dependent cytoplasmic trafficking in Ustilago maydis. PLoS Genet 2014; 10:e1004046. [PMID: 24391515 PMCID: PMC3879195 DOI: 10.1371/journal.pgen.1004046] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 10/30/2013] [Indexed: 12/23/2022] Open
Abstract
The conserved NineTeen protein complex (NTC) is an integral subunit of the spliceosome and required for intron removal during pre-mRNA splicing. The complex associates with the spliceosome and participates in the regulation of conformational changes of core spliceosomal components, stabilizing RNA-RNA- as well as RNA-protein interactions. In addition, the NTC is involved in cell cycle checkpoint control, response to DNA damage, as well as formation and export of mRNP-particles. We have identified the Num1 protein as the homologue of SPF27, one of NTC core components, in the basidiomycetous fungus Ustilago maydis. Num1 is required for polarized growth of the fungal hyphae, and, in line with the described NTC functions, the num1 mutation affects the cell cycle and cell division. The num1 deletion influences splicing in U. maydis on a global scale, as RNA-Seq analysis revealed increased intron retention rates. Surprisingly, we identified in a screen for Num1 interacting proteins not only NTC core components as Prp19 and Cef1, but several proteins with putative functions during vesicle-mediated transport processes. Among others, Num1 interacts with the motor protein Kin1 in the cytoplasm. Similar phenotypes with respect to filamentous and polar growth, vacuolar morphology, as well as the motility of early endosomes corroborate the genetic interaction between Num1 and Kin1. Our data implicate a previously unidentified connection between a component of the splicing machinery and cytoplasmic transport processes. As the num1 deletion also affects cytoplasmic mRNA transport, the protein may constitute a novel functional interconnection between the two disparate processes of splicing and trafficking. In eukaryotic cells, nascent mRNA is processed by splicing to remove introns and to join the exon sequences. The processed mRNA is then transported out of the nucleus and employed by ribosomes to synthesize proteins. Splicing is achieved by the spliceosome and associated protein complexes, among them the so-called NineTeen complex (NTC). We have identified the Num1 protein as one of the core components of the NTC in the fungus Ustilago maydis, and could show that it is required for polarized growth of the filamentous fungal cells. Consistent with the NTC function, cells with a num1-deletion show reduced splicing of mRNA. Moreover, we uncover a novel cytoplasmic function of the Num1 protein: It physically interacts with the microtubule-associated Kinesin 1 motor protein, and phenotypic analyses corroborate that both proteins are functionally connected. Our findings reveal a yet unidentified role of a global splicing factor during intracellular trafficking processes. A possible connection between these disparate mechanisms presumably resides in mRNA-export out of the nucleus and/or the transport of mRNA within the cytoplasm.
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91
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Terfrüchte M, Joehnk B, Fajardo-Somera R, Braus GH, Riquelme M, Schipper K, Feldbrügge M. Establishing a versatile Golden Gate cloning system for genetic engineering in fungi. Fungal Genet Biol 2014; 62:1-10. [DOI: 10.1016/j.fgb.2013.10.012] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 10/24/2013] [Accepted: 10/27/2013] [Indexed: 11/25/2022]
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92
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Baumann S, König J, Koepke J, Feldbrügge M. Endosomal transport of septin mRNA and protein indicates local translation on endosomes and is required for correct septin filamentation. EMBO Rep 2013; 15:94-102. [PMID: 24355572 DOI: 10.1002/embr.201338037] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Endosomes transport lipids and proteins over long distances by shuttling along microtubules. They also carry mRNAs on their surface, but the precise molecular function of this trafficking process is unknown. By live cell imaging of polarized fungal hyphae, we show microtubule-dependent transport of septin mRNA and encoded septin protein on the same shuttling endosomes. Consistent with the hypothesis that septin mRNA is translated on endosomes, the accumulation of septin protein on endosomes requires the recruitment of septin mRNA. Furthermore, ribosomal proteins co-localise with shuttling endosomes, but only if mRNA is present. Importantly, endosomal trafficking is essential for an efficient delivery of septin protein to filaments at growth poles, a process necessary to establish unipolar growth. Thus, we propose that local mRNA translation loads endosomes with septins for assembly and efficient delivery to septin filaments.
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Affiliation(s)
- Sebastian Baumann
- Institute for Microbiology, Cluster of Excellence on Plant Sciences Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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93
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Ooi CP, Bastin P. More than meets the eye: understanding Trypanosoma brucei morphology in the tsetse. Front Cell Infect Microbiol 2013; 3:71. [PMID: 24312899 PMCID: PMC3826061 DOI: 10.3389/fcimb.2013.00071] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 10/14/2013] [Indexed: 11/13/2022] Open
Abstract
T. brucei, the causative parasite for African trypanosomiasis, faces an interesting dilemma in its life cycle. It has to successfully complete its infection cycle in the tsetse vector to be able to infect other vertebrate hosts. T. brucei has to undergo multiple morphological changes as it invades the alimentary canal of the tsetse to finally achieve infectivity in the salivary glands. In this review, we attempt to elucidate how these morphological changes are possible for a parasite that has evolved a highly robust cell structure to survive the chemically and physically diverse environments it finds itself in. To achieve this, we juxtaposed the experimental evidence that has been collected from T. brucei forms that are cultured in vitro with the observations that have been carried out on tsetse-infective forms in vivo. Although the accumulated knowledge on T. brucei biology is by no means trivial, several outstanding questions remain for how the parasite mechanistically changes its morphology as it traverses the tsetse and how those changes are triggered. However, we conclude that with recent breakthroughs allowing for the replication of the tsetse-infection process of T. brucei in vitro, these outstanding questions can finally be addressed.
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Affiliation(s)
| | - Philippe Bastin
- Trypanosome Cell Biology Unit, CNRS URA2581, Institut PasteurParis, France
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94
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Affiliation(s)
- Vera Göhre
- Heinrich-Heine University Düsseldorf, Institute for Microbiology, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Carl Haag
- Heinrich-Heine University Düsseldorf, Institute for Microbiology, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Michael Feldbrügge
- Heinrich-Heine University Düsseldorf, Institute for Microbiology, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
- * E-mail:
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95
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Heimel K, Freitag J, Hampel M, Ast J, Bölker M, Kämper J. Crosstalk between the unfolded protein response and pathways that regulate pathogenic development in Ustilago maydis. THE PLANT CELL 2013; 25:4262-77. [PMID: 24179126 PMCID: PMC3877826 DOI: 10.1105/tpc.113.115899] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The unfolded protein response (UPR) is a conserved eukaryotic signaling pathway regulating endoplasmic reticulum (ER) homeostasis during ER stress, which results, for example, from an increased demand for protein secretion. Here, we characterize the homologs of the central UPR regulatory proteins Hac1 (for Homologous to ATF/CREB1) and Inositol Requiring Enzyme1 in the plant pathogenic fungus Ustilago maydis and demonstrate that the UPR is tightly interlinked with the b mating-type-dependent signaling pathway that regulates pathogenic development. Exact timing of UPR is required for virulence, since premature activation interferes with the b-dependent switch from budding to filamentous growth. In addition, we found crosstalk between UPR and the b target Clampless1 (Clp1), which is essential for cell cycle release and proliferation in planta. The unusual C-terminal extension of the U. maydis Hac1 homolog, Cib1 (for Clp1 interacting bZIP1), mediates direct interaction with Clp1. The interaction between Clp1 and Cib1 promotes stabilization of Clp1, resulting in enhanced ER stress tolerance that prevents deleterious UPR hyperactivation. Thus, the interaction between Cib1 and Clp1 constitutes a checkpoint to time developmental progression and increased secretion of effector proteins at the onset of biotrophic development. Crosstalk between UPR and the b mating-type regulated developmental program adapts ER homeostasis to the changing demands during biotrophy.
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Affiliation(s)
- Kai Heimel
- Georg-August-University Göttingen, Institute for Microbiology and Genetics, Department of Molecular Microbiology and Genetics, 37077 Goettingen, Germany
- Karlsruhe Institute of Technology, Institute for Applied Bioscience, Department of Genetics, 76187 Karlsruhe, Germany
| | - Johannes Freitag
- Philipps-University Marburg, Department of Biology, 35032 Marburg, Germany
- LOEWE Centre for Synthetic Microbiology (SYNMIKRO), 35032 Marburg, Germany
| | - Martin Hampel
- Georg-August-University Göttingen, Institute for Microbiology and Genetics, Department of Molecular Microbiology and Genetics, 37077 Goettingen, Germany
| | - Julia Ast
- Philipps-University Marburg, Department of Biology, 35032 Marburg, Germany
| | - Michael Bölker
- Philipps-University Marburg, Department of Biology, 35032 Marburg, Germany
- LOEWE Centre for Synthetic Microbiology (SYNMIKRO), 35032 Marburg, Germany
- Address correspondence to
| | - Jörg Kämper
- Karlsruhe Institute of Technology, Institute for Applied Bioscience, Department of Genetics, 76187 Karlsruhe, Germany
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96
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Blasius TL, Reed N, Slepchenko BM, Verhey KJ. Recycling of kinesin-1 motors by diffusion after transport. PLoS One 2013; 8:e76081. [PMID: 24098765 PMCID: PMC3786890 DOI: 10.1371/journal.pone.0076081] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 08/20/2013] [Indexed: 11/18/2022] Open
Abstract
Kinesin motors drive the long-distance anterograde transport of cellular components along microtubule tracks. Kinesin-dependent transport plays a critical role in neurogenesis and neuronal function due to the large distance separating the soma and nerve terminal. The fate of kinesin motors after delivery of their cargoes is unknown but has been postulated to involve degradation at the nerve terminal, recycling via retrograde motors, and/or recycling via diffusion. We set out to test these models concerning the fate of kinesin-1 motors after completion of transport in neuronal cells. We find that kinesin-1 motors are neither degraded nor returned by retrograde motors. By combining mathematical modeling and experimental analysis, we propose a model in which the distribution and recycling of kinesin-1 motors fits a “loose bucket brigade” where individual motors alter between periods of active transport and free diffusion within neuronal processes. These results suggest that individual kinesin-1 motors are utilized for multiple rounds of transport.
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Affiliation(s)
- T. Lynne Blasius
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Nathan Reed
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Boris M. Slepchenko
- R. D. Berlin Center for Cell Analysis and Modeling, Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Kristen J. Verhey
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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97
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Neurospora crassa NKIN2, a kinesin-3 motor, transports early endosomes and is required for polarized growth. EUKARYOTIC CELL 2013; 12:1020-32. [PMID: 23687116 DOI: 10.1128/ec.00081-13] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Biological motors are molecular nanomachines, which convert chemical energy into mechanical forces. The combination of mechanoenzymes with structural components, such as the cytoskeleton, enables eukaryotic cells to overcome entropy, generate molecular gradients, and establish polarity. Hyphae of filamentous fungi are among the most polarized cells, and polarity defects are most obvious. Here, we studied the role of the kinesin-3 motor, NKIN2, in Neurospora crassa. We found that NKIN2 localizes as fast-moving spots in the cytoplasm of mature hyphae. To test whether the spots represented early endosomes, the Rab5 GTPase YPT52 was used as an endosomal marker. NKIN2 colocalized with YPT52. Deletion of nkin2 caused strongly reduced endosomal movement. Combined, these results confirm the involvement of NKIN2 in early endosome transport. Introduction of a rigor mutation into NKIN2 labeled with green fluorescent protein (GFP) resulted in decoration of microtubules. Interestingly, NKIN2(rigor) was associated with a subpopulation of microtubules, as had been shown earlier for the Aspergillus nidulans orthologue UncA. Other kinesins did not show this specificity.
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98
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Wu S, Gallagher KL. Intact microtubules are required for the intercellular movement of the SHORT-ROOT transcription factor. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 74:148-159. [PMID: 23294290 DOI: 10.1111/tpj.12112] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 12/11/2012] [Accepted: 01/02/2013] [Indexed: 05/28/2023]
Abstract
In both plants and animals, cell-to-cell signaling controls key aspects of development. In plants, cells communicate through direct transfer of transcription factors between cells. It is thought that most, if not all, mobile transcription factors move via plasmodesmata, membrane-lined channels that connect nearly all cells in the plant. However, the mechanisms by which these proteins access the plasmodesmata are not known. Using four independent assays, we examined the movement of the SHORT-ROOT (SHR) transcription factor under conditions that affect microtubule stability, organization or dynamics. We found that intact microtubules are required for cell-to-cell trafficking of SHR. Either chemical or genetic disruption of microtubules results in a significant reduction in SHR transport. Interestingly, inhibition of microtubules also results in mis-localization of the SHR-INTERACTING EMBRYONIC LETHAL (SIEL) protein, which has been shown to bind directly to SHR and is required for SHR movement. These results show that microtubules facilitate cell-to-cell transport of an endogenous plant protein.
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Affiliation(s)
- Shuang Wu
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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99
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Feldbrügge M, Kellner R, Schipper K. The biotechnological use and potential of plant pathogenic smut fungi. Appl Microbiol Biotechnol 2013; 97:3253-65. [DOI: 10.1007/s00253-013-4777-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 02/12/2013] [Accepted: 02/13/2013] [Indexed: 01/03/2023]
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100
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Zivraj KH, Rehbein M, Ölschläger-Schütt J, Schob C, Falley K, Buck F, Schweizer M, Schepis A, Kremmer E, Richter D, Kreienkamp HJ, Kindler S. The RNA-binding protein MARTA2 regulates dendritic targeting of MAP2 mRNAs in rat neurons. J Neurochem 2013; 124:670-84. [PMID: 23121659 DOI: 10.1111/jnc.12079] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 10/08/2012] [Accepted: 10/13/2012] [Indexed: 11/30/2022]
Abstract
Dendritic targeting of mRNAs encoding the microtubule-associated protein 2 (MAP2) in neurons involves a cis-acting dendritic targeting element. Two rat brain proteins, MAP2-RNA trans-acting protein (MARTA)1 and MARTA2, bind to the cis-element with both high affinity and specificity. In this study, affinity-purified MARTA2 was identified as orthologue of human far-upstream element binding protein 3. In neurons, it resides in somatodendritic granules and dendritic spines and associates with MAP2 mRNAs. Expression of a dominant-negative variant of MARTA2 disrupts dendritic targeting of endogenous MAP2 mRNAs, while not noticeably altering the level and subcellular distribution of polyadenylated mRNAs as a whole. Finally, MAP2 transcripts associate with the microtubule-based motor KIF5 and inhibition of KIF5, but not cytoplasmic dynein function disrupts extrasomatic trafficking of MAP2 mRNA granules. Thus, in neurons MARTA2 appears to represent a key trans-acting factor involved in KIF5-mediated dendritic targeting of MAP2 mRNAs.
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Affiliation(s)
- Krishna H Zivraj
- Institute for Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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