1
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Shah P, Bao Z, Zaidel-Bar R. Visualizing and quantifying molecular and cellular processes in C. elegans using light microscopy. Genetics 2022; 221:6619563. [PMID: 35766819 DOI: 10.1093/genetics/iyac068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 04/14/2022] [Indexed: 11/14/2022] Open
Abstract
Light microscopes are the cell and developmental biologists' "best friend", providing a means to see structures and follow dynamics from the protein to the organism level. A huge advantage of C. elegans as a model organism is its transparency, which coupled with its small size means that nearly every biological process can be observed and measured with the appropriate probe and light microscope. Continuous improvement in microscope technologies along with novel genome editing techniques to create transgenic probes have facilitated the development and implementation of a dizzying array of methods for imaging worm embryos, larvae and adults. In this review we provide an overview of the molecular and cellular processes that can be visualized in living worms using light microscopy. A partial inventory of fluorescent probes and techniques successfully used in worms to image the dynamics of cells, organelles, DNA, and protein localization and activity is followed by a practical guide to choosing between various imaging modalities, including widefield, confocal, lightsheet, and structured illumination microscopy. Finally, we discuss the available tools and approaches, including machine learning, for quantitative image analysis tasks, such as colocalization, segmentation, object tracking, and lineage tracing. Hopefully, this review will inspire worm researchers who have not yet imaged their worms to begin, and push those who are imaging to go faster, finer, and longer.
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Affiliation(s)
- Pavak Shah
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles 90095, USA
| | - Zhirong Bao
- Developmental Biology Program, Sloan Kettering Institute, New York, New York 10065, USA
| | - Ronen Zaidel-Bar
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
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2
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Koyuncu S, Loureiro R, Lee HJ, Wagle P, Krueger M, Vilchez D. Rewiring of the ubiquitinated proteome determines ageing in C. elegans. Nature 2021; 596:285-290. [PMID: 34321666 PMCID: PMC8357631 DOI: 10.1038/s41586-021-03781-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 06/29/2021] [Indexed: 12/20/2022]
Abstract
Ageing is driven by a loss of cellular integrity1. Given the major role of ubiquitin modifications in cell function2, here we assess the link between ubiquitination and ageing by quantifying whole-proteome ubiquitin signatures in Caenorhabditis elegans. We find a remodelling of the ubiquitinated proteome during ageing, which is ameliorated by longevity paradigms such as dietary restriction and reduced insulin signalling. Notably, ageing causes a global loss of ubiquitination that is triggered by increased deubiquitinase activity. Because ubiquitination can tag proteins for recognition by the proteasome3, a fundamental question is whether deficits in targeted degradation influence longevity. By integrating data from worms with a defective proteasome, we identify proteasomal targets that accumulate with age owing to decreased ubiquitination and subsequent degradation. Lowering the levels of age-dysregulated proteasome targets prolongs longevity, whereas preventing their degradation shortens lifespan. Among the proteasomal targets, we find the IFB-2 intermediate filament4 and the EPS-8 modulator of RAC signalling5. While increased levels of IFB-2 promote the loss of intestinal integrity and bacterial colonization, upregulation of EPS-8 hyperactivates RAC in muscle and neurons, and leads to alterations in the actin cytoskeleton and protein kinase JNK. In summary, age-related changes in targeted degradation of structural and regulatory proteins across tissues determine longevity.
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Affiliation(s)
- Seda Koyuncu
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Rute Loureiro
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Hyun Ju Lee
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Prerana Wagle
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Marcus Krueger
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - David Vilchez
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.
- Faculty of Medicine, University Hospital Cologne, Cologne, Germany.
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3
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Remmelzwaal S, Geisler F, Stucchi R, van der Horst S, Pasolli M, Kroll JR, Jarosinska OD, Akhmanova A, Richardson CA, Altelaar M, Leube RE, Ramalho JJ, Boxem M. BBLN-1 is essential for intermediate filament organization and apical membrane morphology. Curr Biol 2021; 31:2334-2346.e9. [PMID: 33857431 DOI: 10.1016/j.cub.2021.03.069] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 02/25/2021] [Accepted: 03/19/2021] [Indexed: 01/07/2023]
Abstract
Epithelial tubes are essential components of metazoan organ systems that control the flow of fluids and the exchange of materials between body compartments and the outside environment. The size and shape of the central lumen confer important characteristics to tubular organs and need to be carefully controlled. Here, we identify the small coiled-coil protein BBLN-1 as a regulator of lumen morphology in the C. elegans intestine. Loss of BBLN-1 causes the formation of bubble-shaped invaginations of the apical membrane into the cytoplasm of intestinal cells and abnormal aggregation of the subapical intermediate filament (IF) network. BBLN-1 interacts with IF proteins and localizes to the IF network in an IF-dependent manner. The appearance of invaginations is a result of the abnormal IF aggregation, indicating a direct role for the IF network in maintaining lumen homeostasis. Finally, we identify bublin (BBLN) as the mammalian ortholog of BBLN-1. When expressed in the C. elegans intestine, BBLN recapitulates the localization pattern of BBLN-1 and can compensate for the loss of BBLN-1 in early larvae. In mouse intestinal organoids, BBLN localizes subapically, together with the IF protein keratin 8. Our results therefore may have implications for understanding the role of IFs in regulating epithelial tube morphology in mammals.
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Affiliation(s)
- Sanne Remmelzwaal
- Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Florian Geisler
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
| | - Riccardo Stucchi
- Cell Biology, Neurobiology and Biophysics, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands; Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Suzanne van der Horst
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands; Oncode Institute, Utrecht, the Netherlands
| | - Milena Pasolli
- Cell Biology, Neurobiology and Biophysics, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Jason R Kroll
- Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Olga D Jarosinska
- Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Anna Akhmanova
- Cell Biology, Neurobiology and Biophysics, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | | | - Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Rudolf E Leube
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
| | - João J Ramalho
- Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
| | - Mike Boxem
- Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
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4
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Yang Z, Mattingly BC, Hall DH, Ackley BD, Buechner M. Terminal web and vesicle trafficking proteins mediate nematode single-cell tubulogenesis. J Cell Biol 2020; 219:e202003152. [PMID: 32860501 PMCID: PMC7594493 DOI: 10.1083/jcb.202003152] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 06/15/2020] [Accepted: 08/03/2020] [Indexed: 11/22/2022] Open
Abstract
Single-celled tubules represent a complicated structure that forms during development, requiring extension of a narrow cytoplasm surrounding a lumen exerting osmotic pressure that can burst the luminal membrane. Genetic studies on the excretory canal cell of Caenorhabditis elegans have revealed many proteins that regulate the cytoskeleton, vesicular transport, and physiology of the narrow canals. Here, we show that βH-spectrin regulates the placement of intermediate filament proteins forming a terminal web around the lumen, and that the terminal web in turn retains a highly conserved protein (EXC-9/CRIP1) that regulates apical endosomal trafficking. EXC-1/IRG, the binding partner of EXC-9, is also localized to the apical membrane and affects apical actin placement and RAB-8-mediated vesicular transport. The results suggest that an intermediate filament protein acts in a novel pathway to direct the traffic of vesicles to locations of lengthening apical surface during single-celled tubule development.
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Affiliation(s)
- Zhe Yang
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
| | | | - David H. Hall
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, NY
| | - Brian D. Ackley
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
| | - Matthew Buechner
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
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5
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Buechner M, Yang Z, Al-Hashimi H. A Series of Tubes: The C. elegans Excretory Canal Cell as a Model for Tubule Development. J Dev Biol 2020; 8:jdb8030017. [PMID: 32906663 PMCID: PMC7557474 DOI: 10.3390/jdb8030017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 12/25/2022] Open
Abstract
Formation and regulation of properly sized epithelial tubes is essential for multicellular life. The excretory canal cell of C. elegans provides a powerful model for investigating the integration of the cytoskeleton, intracellular transport, and organismal physiology to regulate the developmental processes of tube extension, lumen formation, and lumen diameter regulation in a narrow single cell. Multiple studies have provided new understanding of actin and intermediate filament cytoskeletal elements, vesicle transport, and the role of vacuolar ATPase in determining tube size. Most of the genes discovered have clear homologues in humans, with implications for understanding these processes in mammalian tissues such as Schwann cells, renal tubules, and brain vasculature. The results of several new genetic screens are described that provide a host of new targets for future studies in this informative structure.
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Affiliation(s)
- Matthew Buechner
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA;
- Correspondence:
| | - Zhe Yang
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA;
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6
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Zárate-Potes A, Yang W, Pees B, Schalkowski R, Segler P, Andresen B, Haase D, Nakad R, Rosenstiel P, Tetreau G, Colletier JP, Schulenburg H, Dierking K. The C. elegans GATA transcription factor elt-2 mediates distinct transcriptional responses and opposite infection outcomes towards different Bacillus thuringiensis strains. PLoS Pathog 2020; 16:e1008826. [PMID: 32970778 PMCID: PMC7513999 DOI: 10.1371/journal.ppat.1008826] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 07/21/2020] [Indexed: 12/20/2022] Open
Abstract
The nematode Caenorhabditis elegans has been extensively used as a model for the study of innate immune responses against bacterial pathogens. While it is well established that the worm mounts distinct transcriptional responses to different bacterial species, it is still unclear in how far it can fine-tune its response to different strains of a single pathogen species, especially if the strains vary in virulence and infection dynamics. To rectify this knowledge gap, we systematically analyzed the C. elegans response to two strains of Bacillus thuringiensis (Bt), MYBt18247 (Bt247) and MYBt18679 (Bt679), which produce different pore forming toxins (PFTs) and vary in infection dynamics. We combined host transcriptomics with cytopathological characterizations and identified both a common and also a differentiated response to the two strains, the latter comprising almost 10% of the infection responsive genes. Functional genetic analyses revealed that the AP-1 component gene jun-1 mediates the common response to both Bt strains. In contrast, the strain-specific response is mediated by the C. elegans GATA transcription factor ELT-2, a homolog of Drosophila SERPENT and vertebrate GATA4-6, and a known master regulator of intestinal responses in the nematode. elt-2 RNAi knockdown decreased resistance to Bt679, but remarkably, increased survival on Bt247. The elt-2 silencing-mediated increase in survival was characterized by reduced intestinal tissue damage despite a high pathogen burden and might thus involve increased tolerance. Additional functional genetic analyses confirmed the involvement of distinct signaling pathways in the C. elegans defense response: the p38-MAPK pathway acts either directly with or in parallel to elt-2 in mediating resistance to Bt679 infection but is not required for protection against Bt247. Our results further suggest that the elt-2 silencing-mediated increase in survival on Bt247 is multifactorial, influenced by the nuclear hormone receptors NHR-99 and NHR-193, and may further involve lipid metabolism and detoxification. Our study highlights that the nematode C. elegans with its comparatively simple immune defense system is capable of generating a differentiated response to distinct strains of the same pathogen species. Importantly, our study provides a molecular insight into the diversity of biological processes that are influenced by a single master regulator and jointly determine host survival after pathogen infection.
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Affiliation(s)
- Alejandra Zárate-Potes
- Department of Evolutionary Ecology and Genetics, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Wentao Yang
- Department of Evolutionary Ecology and Genetics, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Barbara Pees
- Department of Evolutionary Ecology and Genetics, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Rebecca Schalkowski
- Department of Evolutionary Ecology and Genetics, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Philipp Segler
- Department of Evolutionary Ecology and Genetics, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Bentje Andresen
- Department of Evolutionary Ecology and Genetics, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Daniela Haase
- Department of Evolutionary Ecology and Genetics, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Rania Nakad
- Department of Evolutionary Ecology and Genetics, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Philip Rosenstiel
- Institute for Clinical Molecular Biology (IKMB), Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Guillaume Tetreau
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, Grenoble, France
| | | | - Hinrich Schulenburg
- Department of Evolutionary Ecology and Genetics, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Ploen, Germany
| | - Katja Dierking
- Department of Evolutionary Ecology and Genetics, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
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7
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Geisler F, Coch RA, Richardson C, Goldberg M, Bevilacqua C, Prevedel R, Leube RE. Intestinal intermediate filament polypeptides in C. elegans: Common and isotype-specific contributions to intestinal ultrastructure and function. Sci Rep 2020; 10:3142. [PMID: 32081918 PMCID: PMC7035338 DOI: 10.1038/s41598-020-59791-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 01/17/2020] [Indexed: 12/11/2022] Open
Abstract
The abundance and diversity of intermediate filaments (IFs) in the C. elegans intestine indicate important contributions to intestinal function and organismal wellbeing. Fluorescent IF reporters localize below the actin-rich brush border and are highly enriched in the lumen-enveloping endotube, which is attached to the C. elegans apical junction. Mapping intestinal viscoelasticity by contact-free Brillouin microscopy reveals that the IF-rich endotube is positioned at the interface between the stiff brush border and soft cytoplasm suggesting a mechanical buffering function to deal with the frequent luminal distortions occurring during food intake and movement. In accordance, depletion of IFB-2, IFC-2 and IFD-2 leads to intestinal lumen dilation although depletion of IFC-1, IFD-1 and IFP-1 do not. Ultrastructural analyses of loss of function mutants further show that IFC-2 mutants have a rarefied endotube and IFB-2 mutants lack an endotube altogether. Remarkably, almost all IFB-2- and IFC-2-deficient animals develop to fertile adults. But developmental retardation, reduced brood size, altered survival and increased sensitivity to microbial toxin, osmotic and oxidative stress are seen in both mutants albeit to different degrees. Taken together, we propose that individual intestinal IF polypeptides contribute in different ways to endotube morphogenesis and cooperate to cope with changing environments.
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Affiliation(s)
- Florian Geisler
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
| | - Richard A Coch
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
| | - Christine Richardson
- School of Biological and Biomedical Sciences, Durham University, Durham, United Kingdom
| | - Martin Goldberg
- School of Biological and Biomedical Sciences, Durham University, Durham, United Kingdom
| | - Carlo Bevilacqua
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Robert Prevedel
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Rudolf E Leube
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany.
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8
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Karabinos A, Schulze E, Baumeister R. Analysis of the novel excretory cell expressed ECP-1 protein and its proposed ECP-1/IFC-2 fusion protein EXC-2 in the nematode Caenorhabditis elegans. Gene Expr Patterns 2019; 34:119061. [DOI: 10.1016/j.gep.2019.119061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 05/15/2019] [Accepted: 06/11/2019] [Indexed: 02/07/2023]
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9
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Karabinos A, Schünemann J, Parry DAD. Promiscuous Dimerization Between the Caenorhabditis elegans IF Proteins and a Hypothesis to Explain How Multiple IFs Persist Over Evolutionary Time. J Mol Evol 2019; 87:221-230. [PMID: 31407015 DOI: 10.1007/s00239-019-09904-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 08/01/2019] [Indexed: 11/28/2022]
Abstract
Our previous calculations of ionic interactions indicated that the Caenorhabditis elegans intermediate filament (IF) IFA proteins, in addition to IFA/IFB-1 heterodimers, may also form homodimers. In order to prove the significance of these calculations, we analysed the dimerization potential of the IFA chains in blot overlays. Unexpectedly, we found here that the dimerization of the IFA-1 protein was of both homotypic and heterotypic nature, and involved all proteins immobilized on the membrane (IFA-1, IFA-2, IFA-4, IFB-1, IFB-2, IFC-1, IFC-2, IFD-1, IFD-2 and IFP-1). A similar interaction profile, though less complex, was observed for two biotinylated proteins (IFA-2 and IFA-4). These and previous results indicate that the IFA proteins are able to form many different heteropolymeric and homopolymeric complexes in the C. elegans tissue, but that only those triggered by the IFA-specific IFB-1 protein result in mature IFs. Moreover, the calculations of the possible ionic interactions between the individual rod sequences as well as their various deletion variants indicated a special role in this process for the middle part of the C. elegans IF coil 1B segment that is deleted in all vertebrate cytoplasmic IFs. We hypothesized here, therefore, that the striking promiscuity of the C. elegans IFs originally involved a nuclear lamin which, due to a two-heptad-long rod deletion, prevented formation of a functional lamin/cIF dimer. This, in concert with an efficient dimerization and a strict tissue-specific co-expression, may allow expansion and maintenance of the multiple Caenorhabditis IFs. A possible implication for evolution of chordate IFs proteins is also discussed.
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Affiliation(s)
- Anton Karabinos
- SEMBID,s.r.o.-Research Centre of Applied Biomedical Diagnostics, Magnezitarska 2/C, 04013, Kosice, Slovakia.
| | - Jürgen Schünemann
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Goettingen, Germany
| | - David A D Parry
- School of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand
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10
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Khan LA, Jafari G, Zhang N, Membreno E, Yan S, Zhang H, Gobel V. A tensile trilayered cytoskeletal endotube drives capillary-like lumenogenesis. J Cell Biol 2019; 218:2403-2424. [PMID: 31239283 PMCID: PMC6605810 DOI: 10.1083/jcb.201811175] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 04/09/2019] [Accepted: 05/14/2019] [Indexed: 01/01/2023] Open
Abstract
Unicellular tubes are components of internal organs and capillaries. It is unclear how they meet the architectural challenge to extend a centered intracellular lumen of uniform diameter. In an RNAi-based Caenorhabditis elegans screen, we identified three intermediate filaments (IFs)-IFA-4, IFB-1, and IFC-2-as interactors of the lumenal membrane-actin linker ERM-1 in excretory-canal tubulogenesis. We find that IFs, generally thought to affect morphogenesis indirectly by maintaining tissue integrity, directly promote lumenogenesis in this capillary-like single-cell tube. We show that ERM-1, ACT-5/actin, and TBB-2/tubulin recruit membrane-forming endosomal and flux-promoting canalicular vesicles to the lumen, whereas IFs, themselves recruited to the lumen by ERM-1 and TBB-2, restrain lateral vesicle access. IFs thereby prevent cystogenesis, equilibrate the lumen diameter, and promote lumen forward extension. Genetic and imaging analyses suggest that IFB-1/IFA-4 and IFB-1/IFC-2 polymers form a perilumenal triple IF lattice, sandwiched between actin and helical tubulin. Our findings characterize a novel mechanism of capillary-like lumenogenesis, where a tensile trilayered cytoskeletal endotube transforms concentric into directional growth.
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Affiliation(s)
- Liakot A Khan
- Mucosal Immunology and Biology Research Center, Developmental Biology and Genetics Core, Massachusetts General Hospital for Children, Harvard Medical School, Boston, MA
| | - Gholamali Jafari
- Mucosal Immunology and Biology Research Center, Developmental Biology and Genetics Core, Massachusetts General Hospital for Children, Harvard Medical School, Boston, MA
| | - Nan Zhang
- Mucosal Immunology and Biology Research Center, Developmental Biology and Genetics Core, Massachusetts General Hospital for Children, Harvard Medical School, Boston, MA
- Key Laboratory of Zoonosis Research, Institute of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Edward Membreno
- Mucosal Immunology and Biology Research Center, Developmental Biology and Genetics Core, Massachusetts General Hospital for Children, Harvard Medical School, Boston, MA
| | - Siyang Yan
- Mucosal Immunology and Biology Research Center, Developmental Biology and Genetics Core, Massachusetts General Hospital for Children, Harvard Medical School, Boston, MA
| | - Hongjie Zhang
- Mucosal Immunology and Biology Research Center, Developmental Biology and Genetics Core, Massachusetts General Hospital for Children, Harvard Medical School, Boston, MA
- Faculty of Health Sciences, University of Macau, Taipa, Macau, China
| | - Verena Gobel
- Mucosal Immunology and Biology Research Center, Developmental Biology and Genetics Core, Massachusetts General Hospital for Children, Harvard Medical School, Boston, MA
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11
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Geisler F, Coch RA, Richardson C, Goldberg M, Denecke B, Bossinger O, Leube RE. The intestinal intermediate filament network responds to and protects against microbial insults and toxins. Development 2019; 146:dev.169482. [PMID: 30630824 DOI: 10.1242/dev.169482] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 12/19/2018] [Indexed: 12/12/2022]
Abstract
The enrichment of intermediate filaments in the apical cytoplasm of intestinal cells is evolutionarily conserved, forming a sheath that is anchored to apical junctions and positioned below the microvillar brush border, which suggests a protective intracellular barrier function. To test this, we used Caenorhabditis elegans, the intestinal cells of which are endowed with a particularly dense intermediate filament-rich layer that is referred to as the endotube. We found alterations in endotube structure and intermediate filament expression upon infection with nematicidal B. thuringiensis or treatment with its major pore-forming toxin crystal protein Cry5B. Endotube impairment due to defined genetic mutations of intermediate filaments and their regulators results in increased Cry5B sensitivity as evidenced by elevated larval arrest, prolonged time of larval development and reduced survival. Phenotype severity reflects the extent of endotube alterations and correlates with reduced rescue upon toxin removal. The results provide in vivo evidence for a major protective role of a properly configured intermediate filament network as an intracellular barrier in intestinal cells. This notion is further supported by increased sensitivity of endotube mutants to oxidative and osmotic stress.
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Affiliation(s)
- Florian Geisler
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
| | - Richard A Coch
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
| | - Christine Richardson
- School of Biological and Biomedical Sciences, Department of Biosciences, Durham University, Durham DH1 3LE, UK
| | - Martin Goldberg
- School of Biological and Biomedical Sciences, Department of Biosciences, Durham University, Durham DH1 3LE, UK
| | - Bernd Denecke
- Genomics Facility, IZKF Aachen, RWTH Aachen University, 52074 Aachen, Germany
| | - Olaf Bossinger
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
| | - Rudolf E Leube
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
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12
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Karabinos A. Intermediate filament (IF) proteins IFA-1 and IFB-1 represent a basic heteropolymeric IF cytoskeleton of nematodes: A molecular phylogeny of nematode IFs. Gene 2019; 692:44-53. [PMID: 30641223 DOI: 10.1016/j.gene.2018.12.069] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 11/17/2018] [Accepted: 12/31/2018] [Indexed: 11/30/2022]
Abstract
Intermediate filaments (IF) belong to major cytoskeletal components of metazoan cells. We have previously determined a tissue specific expression and assembly properties of all eleven cytoplasmic IFs (IFA-1 - IFA-4, IFB-1, IFB-2, IFC-1, IFC-2, IFD-1, IFD-2, IFP-1) in C. elegans and reported an essential function for four (IFA-1, IFA-2, IFA-3 and IFB-1) of them. In this study we continued the characterisation of the IF proteins in C. elegans by searching for in vivo polymerisation partners of the IFA proteins. Using the murine IFA-1 to IFA-3-specific monoclonal Ab MH4 and the immunoprecipitation assay as a tool, we identified the heteropolymeric IFA-1/IFB-1 complexes in the whole nematode protein extract, confirming their existence also in vivo. Moreover, in the present study we also analysed evolutionary aspects of the IF proteins in C. elegans and in nematodes. We found 106 C. elegans IF homologs in different nematode clades. Phylogenetic analyses suggest that all nematode IFs (including the three newly identified IF sequences IFA-5, IFCDP-1 and IFCDP-2) might arose from a AB-type IF ancestor through repeated gene duplications and sequence divergence. Interestingly, the C. elegans IF proteins IFA-1 and IFB-1 represent a heteropolymeric IF cytoskeleton in all investigated nematode clades, in contrast to other sequences restricted to the clade III-V (IFA-2, IFA-4), III (IFA-5) and V (IFB-2, IFCDP) taxa, or even to the Caenorhabditis genus (IFA-3, IFC-1 to IFP-1). These analyses provide an insight into the origin of the multiple IFs in nematodes and also represent a basis for further studies of these sequences in nematodes.
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Affiliation(s)
- Anton Karabinos
- SEMBID, s.r.o.-Research Centre of Applied Biomedical Diagnostics, Magnezitarska 2/C, 04013 Kosice, Slovakia.
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13
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Shi L, Jia X, Guo T, Cheng L, Han X, Wu Q, Wang D. A circular RNA circ_0000115 in response to graphene oxide in nematodes. RSC Adv 2019; 9:13722-13735. [PMID: 35519596 PMCID: PMC9063864 DOI: 10.1039/c9ra00997c] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 04/29/2019] [Indexed: 12/03/2022] Open
Abstract
Circular RNAs (circRNAs) play important roles in regulating various biological processes; however, their roles in regulating the toxicity of engineered nanomaterials (ENMs) are still unclear. Based on Illumina HiSeq2500 sequencing, we here identified 43 dysregulated circRNAs in graphene oxide (GO) (1 mg L−1) exposed nematodes. Five of these candidate circRNAs could be further dysregulated by GO exposure in the range of μg L−1. Using the RNA interference (RNAi) technique, we found that the alteration in expressions of circ_0000115, circ_0000247, and circ_0000665 mediated a protective response to GO exposure; however, the alteration in expressions of circ_0000201 and circ_0000308 mediated the toxicity induction of GO. In nematodes, the circ_0000115 acted in certain tissues (intestine and neurons) to regulate GO toxicity. Moreover, an intermediate filament protein IFC-2 required for intestinal development was identified as a target of circ_0000115 in regulating the GO toxicity. In the intestine, intestinal IFC-2 acted further upstream of FOXO transcriptional factor DAF-16 in the insulin signaling pathway to regulate the GO toxicity. Therefore, intestinal circ_0000115 in the signaling cascade of circ_0000115-IFC-2-DAF-16 regulates the GO toxicity by modulating the function of IFC-2. Circular RNAs (circRNAs) play important roles in regulating various biological processes; however, their roles in regulating the toxicity of engineered nanomaterials (ENMs) are still unclear.![]()
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Affiliation(s)
- Lifang Shi
- Key Laboratory of Environmental Medicine Engineering in Ministry of Education
- Medical School
- Southeast University
- Nanjing 210009
- China
| | - Xiaohuan Jia
- Key Laboratory of Environmental Medicine Engineering in Ministry of Education
- Medical School
- Southeast University
- Nanjing 210009
- China
| | - Tiantian Guo
- Key Laboratory of Environmental Medicine Engineering in Ministry of Education
- Medical School
- Southeast University
- Nanjing 210009
- China
| | - Lu Cheng
- Key Laboratory of Environmental Medicine Engineering in Ministry of Education
- Medical School
- Southeast University
- Nanjing 210009
- China
| | - Xiaoxiao Han
- Key Laboratory of Environmental Medicine Engineering in Ministry of Education
- Medical School
- Southeast University
- Nanjing 210009
- China
| | - Qiuli Wu
- Key Laboratory of Environmental Medicine Engineering in Ministry of Education
- Medical School
- Southeast University
- Nanjing 210009
- China
| | - Dayong Wang
- Key Laboratory of Environmental Medicine Engineering in Ministry of Education
- Medical School
- Southeast University
- Nanjing 210009
- China
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The Caenorhabditis elegans SMOC-1 Protein Acts Cell Nonautonomously To Promote Bone Morphogenetic Protein Signaling. Genetics 2018; 211:683-702. [PMID: 30518528 DOI: 10.1534/genetics.118.301805] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Accepted: 12/04/2018] [Indexed: 01/20/2023] Open
Abstract
Bone morphogenetic protein (BMP) signaling regulates many different developmental and homeostatic processes in metazoans. The BMP pathway is conserved in Caenorhabditis elegans, and is known to regulate body size and mesoderm development. We have identified the C. elegans smoc-1 (Secreted MOdular Calcium-binding protein-1) gene as a new player in the BMP pathway. smoc-1(0) mutants have a small body size, while overexpression of smoc-1 leads to a long body size and increased expression of the RAD-SMAD (reporter acting downstream of SMAD) BMP reporter, suggesting that SMOC-1 acts as a positive modulator of BMP signaling. Using double-mutant analysis, we showed that SMOC-1 antagonizes the function of the glypican LON-2 and acts through the BMP ligand DBL-1 to regulate BMP signaling. Moreover, SMOC-1 appears to specifically regulate BMP signaling without significant involvement in a TGFβ-like pathway that regulates dauer development. We found that smoc-1 is expressed in multiple tissues, including cells of the pharynx, intestine, and posterior hypodermis, and that the expression of smoc-1 in the intestine is positively regulated by BMP signaling. We further established that SMOC-1 functions cell nonautonomously to regulate body size. Human SMOC1 and SMOC2 can each partially rescue the smoc-1(0) mutant phenotype, suggesting that SMOC-1's function in modulating BMP signaling is evolutionarily conserved. Together, our findings highlight a conserved role of SMOC proteins in modulating BMP signaling in metazoans.
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Tubular Excretory Canal Structure Depends on Intermediate Filaments EXC-2 and IFA-4 in Caenorhabditis elegans. Genetics 2018; 210:637-652. [PMID: 29945901 DOI: 10.1534/genetics.118.301078] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 05/23/2018] [Indexed: 12/28/2022] Open
Abstract
The excretory canals of Caenorhabditis elegans are a model for understanding the maintenance of apical morphology in narrow single-celled tubes. Light and electron microscopy shows that mutants in exc-2 start to form canals normally, but these swell to develop large fluid-filled cysts that lack a complete terminal web at the apical surface, and accumulate filamentous material in the canal lumen. Here, whole-genome sequencing and gene rescue show that exc-2 encodes intermediate filament protein IFC-2 EXC-2/IFC-2 protein, fluorescently tagged via clustered regularly interspaced short palindromic repeats/Cas9, is located at the apical surface of the canals independently of other intermediate filament proteins. EXC-2 is also located in several other tissues, though the tagged isoforms are not seen in the larger intestinal tube. Tagged EXC-2 binds via pulldown to intermediate filament protein IFA-4, which is also shown to line the canal apical surface. Overexpression of either protein results in narrow but shortened canals. These results are consistent with a model whereby three intermediate filaments in the canals-EXC-2, IFA-4, and IFB-1-restrain swelling of narrow tubules in concert with actin filaments that guide the extension and direction of tubule outgrowth, while allowing the tube to bend as the animal moves.
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Karabinos A, Schünemann J, Parry DAD. Assembly studies of six intestinal intermediate filament (IF) proteins B2, C1, C2, D1, D2, and E1 in the nematode C. elegans. Cytoskeleton (Hoboken) 2017; 74:107-113. [PMID: 28063204 DOI: 10.1002/cm.21354] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 12/25/2016] [Accepted: 01/04/2017] [Indexed: 12/31/2022]
Abstract
The dimerisation properties of six intestine-expressed intermediate filament (IF) proteins (B2, C1, C2, D1, D2, E1) were analysed in blot overlay assay on membranes containing all of the eleven recombinant C. elegans IF proteins (A1, A2, A3, A4, B1, B2, C1, C2, D1, D2, and E1). The interactions detected in the blot assays exclusively comprise intestine-expressed IF proteins and the protein A4, which is found in the dauer larva intestine. About 86% of these interactions are heterotypic, while the remaining interactions relate to C1, C2, and D2 homodimers. These multiple modes of interaction were also supported by calculations of the numbers of possible interchain ionic interactions derived from the individual rod sequences. The results predict that the six B2, C1, C2, D1, D2, and E1 IF proteins are able to form as many as eleven different heteropolymeric and three homopolymeric IFs in the C. elegans intestine. This simple model of the intestinal IF meshwork enables us to speculate that our previously reported triple RNAi worms arrested or decreased their growth because of feeding reduction due to morphological defects of the mechanically compromised intestine.
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Affiliation(s)
- Anton Karabinos
- SEMBID, s.r.o.-Research Centre of Applied Biomedical Diagnostics, Magnezitarska 2/C, Kosice, 04013, Slovakia
| | - Jürgen Schünemann
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Goettingen, 37077, Germany
| | - David A D Parry
- Institute of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand
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Geisler F, Gerhardus H, Carberry K, Davis W, Jorgensen E, Richardson C, Bossinger O, Leube RE. A novel function for the MAP kinase SMA-5 in intestinal tube stability. Mol Biol Cell 2016; 27:3855-3868. [PMID: 27733627 PMCID: PMC5170608 DOI: 10.1091/mbc.e16-02-0099] [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: 02/17/2016] [Revised: 09/26/2016] [Accepted: 10/05/2016] [Indexed: 01/19/2023] Open
Abstract
In vivo evidence links SMA-5 to the maintenance of the apical domain in the Caenorhabditis elegans intestine. sma-5 mutations induce morphological and biochemical changes of the intermediate filament system, demonstrating the close relationship between posttranslational modification and structural integrity of the evolutionarily conserved intestinal cytoskeleton. Intermediate filaments are major cytoskeletal components whose assembly into complex networks and isotype-specific functions are still largely unknown. Caenorhabditis elegans provides an excellent model system to study intermediate filament organization and function in vivo. Its intestinal intermediate filaments localize exclusively to the endotube, a circumferential sheet just below the actin-based terminal web. A genetic screen for defects in the organization of intermediate filaments identified a mutation in the catalytic domain of the MAP kinase 7 orthologue sma-5(kc1). In sma-5(kc1) mutants, pockets of lumen penetrate the cytoplasm of the intestinal cells. These membrane hernias increase over time without affecting epithelial integrity and polarity. A more pronounced phenotype was observed in the deletion allele sma-5(n678) and in intestine-specific sma-5(RNAi). Besides reduced body length, an increased time of development, reduced brood size, and reduced life span were observed in the mutants, indicating compromised food uptake. Ultrastructural analyses revealed that the luminal pockets include the subapical cytoskeleton and coincide with local thinning and gaps in the endotube that are often enlarged in other regions. Increased intermediate filament phosphorylation was detected by two-dimensional immunoblotting, suggesting that loss of SMA-5 function leads to reduced intestinal tube stability due to altered intermediate filament network phosphorylation.
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Affiliation(s)
- Florian Geisler
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
| | - Harald Gerhardus
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
| | - Katrin Carberry
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
| | - Wayne Davis
- Department of Biology and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112-0840
| | - Erik Jorgensen
- Department of Biology and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112-0840
| | - Christine Richardson
- School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, United Kingdom
| | - Olaf Bossinger
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
| | - Rudolf E Leube
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
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18
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Riddle MR, Spickard EA, Jevince A, Nguyen KCQ, Hall DH, Joshi PM, Rothman JH. Transorganogenesis and transdifferentiation in C. elegans are dependent on differentiated cell identity. Dev Biol 2016; 420:136-147. [PMID: 27717645 PMCID: PMC5224929 DOI: 10.1016/j.ydbio.2016.09.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 09/12/2016] [Accepted: 09/23/2016] [Indexed: 10/25/2022]
Abstract
The differentiated cell identities and structure of fully formed organs are generally stable after their development. In contrast, we report here that development of the C. elegans proximal somatic gonad (hermaphrodite uterus and spermathecae, and male vas deferens) can be redirected into intestine-like organs by brief expression of the ELT-7 GATA transcription factor. This process converts one developing organ into another and can hence be considered "transorganogenesis." We show that, following pulsed ELT-7 expression, cells of the uterus activate and maintain intestine-specific gene expression and are transformed at the ultrastructural level to form an epithelial tube resembling the normal intestine formed during embryogenesis. Ubiquitous ELT-7 expression activates intestinal markers in many different cell types but only cells in the somatic gonad and pharynx appear to become fully reprogrammed. We found that ectopic expression of other endoderm-promoting transcription factors, but not muscle- or ectoderm- promoting transcription factors, redirects the fate of these organs, suggesting that pharyngeal and somatic gonad cells are specifically competent to adopt intestine identity. Although the intestine, pharynx, and somatic gonad are derived from distant cell lineages, they all express the PHA-4/FoxA transcription factor. While we found that post-embryonic PHA-4 is not necessary for pharynx or uterus reprogramming and PHA-4 is not sufficient in combination with ELT-7 to induce reprogramming in other cells types, knock down of PHA-4 during embryogenesis, which abolishes normal pharynx differentiation, prevents pharyngeal precursors from being reprogrammed into intestine. These results suggest that differentiated cell identity determines susceptibility to transdifferentiation and highlight the importance of cellular context in controlling competency for reprogramming.
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Affiliation(s)
- Misty R Riddle
- Department of Molecular, Cellular, and Developmental Biology, and Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
| | - Erik A Spickard
- Department of Molecular, Cellular, and Developmental Biology, and Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
| | - Angela Jevince
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Ken C Q Nguyen
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - David H Hall
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Pradeep M Joshi
- Department of Molecular, Cellular, and Developmental Biology, and Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
| | - Joel H Rothman
- Department of Molecular, Cellular, and Developmental Biology, and Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA; School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand
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Coch RA, Leube RE. Intermediate Filaments and Polarization in the Intestinal Epithelium. Cells 2016; 5:E32. [PMID: 27429003 PMCID: PMC5040974 DOI: 10.3390/cells5030032] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/05/2016] [Accepted: 07/06/2016] [Indexed: 01/02/2023] Open
Abstract
The cytoplasmic intermediate filament cytoskeleton provides a tissue-specific three-dimensional scaffolding with unique context-dependent organizational features. This is particularly apparent in the intestinal epithelium, in which the intermediate filament network is localized below the apical terminal web region and is anchored to the apical junction complex. This arrangement is conserved from the nematode Caenorhabditis elegans to humans. The review summarizes compositional, morphological and functional features of the polarized intermediate filament cytoskeleton in intestinal cells of nematodes and mammals. We emphasize the cross talk of intermediate filaments with the actin- and tubulin-based cytoskeleton. Possible links of the intermediate filament system to the distribution of apical membrane proteins and the cell polarity complex are highlighted. Finally, we discuss how these properties relate to the establishment and maintenance of polarity in the intestine.
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Affiliation(s)
- Richard A Coch
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Wendlingweg 2, Aachen 52074, Germany.
| | - Rudolf E Leube
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Wendlingweg 2, Aachen 52074, Germany.
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20
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Geisler F, Leube RE. Epithelial Intermediate Filaments: Guardians against Microbial Infection? Cells 2016; 5:cells5030029. [PMID: 27355965 PMCID: PMC5040971 DOI: 10.3390/cells5030029] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 06/15/2016] [Accepted: 06/21/2016] [Indexed: 12/21/2022] Open
Abstract
Intermediate filaments are abundant cytoskeletal components of epithelial tissues. They have been implicated in overall stress protection. A hitherto poorly investigated area of research is the function of intermediate filaments as a barrier to microbial infection. This review summarizes the accumulating knowledge about this interaction. It first emphasizes the unique spatial organization of the keratin intermediate filament cytoskeleton in different epithelial tissues to protect the organism against microbial insults. We then present examples of direct interaction between viral, bacterial, and parasitic proteins and the intermediate filament system and describe how this affects the microbe-host interaction by modulating the epithelial cytoskeleton, the progression of infection, and host response. These observations not only provide novel insights into the dynamics and function of intermediate filaments but also indicate future avenues to combat microbial infection.
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Affiliation(s)
- Florian Geisler
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany.
| | - Rudolf E Leube
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany.
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Jahnel O, Hoffmann B, Merkel R, Bossinger O, Leube RE. Mechanical Probing of the Intermediate Filament-Rich Caenorhabditis Elegans Intestine. Methods Enzymol 2015; 568:681-706. [PMID: 26795489 DOI: 10.1016/bs.mie.2015.08.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
It is commonly accepted that intermediate filaments have an important mechanical function. This function relies not only on intrinsic material properties but is also determined by dynamic interactions with other cytoskeletal filament systems, distinct cell adhesion sites, and cellular organelles which are fine-tuned by multiple signaling pathways. While aspects of these properties and processes can be studied in vitro, their full complexity can only be understood in a viable tissue context. Yet, suitable and easily accessible model systems for monitoring tissue mechanics at high precision are rare. We show that the dissected intestine of the genetic model organism Caenorhabditis elegans fulfills this requirement. The 20 intestinal cells, which are arranged in an invariant fashion, are characterized by a dense subapical mesh of intermediate filaments that are attached to the C. elegans apical junction. We present procedures to visualize details of the characteristic intermediate filament-junctional complex arrangement in living animals. We then report on methods to prepare intestines with a fully intact intermediate filament cytoskeleton and detail procedures to assess their viability. A dual micropipette assay is described to measure mechanical properties of the dissected intestine while monitoring the spatial arrangement of the intermediate filament system. Advantages of this approach are (i) the high reproducibility of measurements because of the uniform architecture of the intestine and (ii) the high degree of accessibility allowing not only mechanical manipulation of an intact tissue but also control of culture medium composition and addition of drugs as well as visualization of cell structures. With this method, examination of worms carrying mutations in the intermediate filament system, its interacting partners and its regulators will become feasible.
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Affiliation(s)
- Oliver Jahnel
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
| | - Bernd Hoffmann
- Institute of Complex Systems, ICS-7: Biomechanics, Jülich, Germany
| | - Rudolf Merkel
- Institute of Complex Systems, ICS-7: Biomechanics, Jülich, Germany
| | - Olaf Bossinger
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
| | - Rudolf E Leube
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany.
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Disruption of the C. elegans Intestinal Brush Border by the Fungal Lectin CCL2 Phenocopies Dietary Lectin Toxicity in Mammals. PLoS One 2015; 10:e0129381. [PMID: 26057124 PMCID: PMC4461262 DOI: 10.1371/journal.pone.0129381] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Accepted: 05/07/2015] [Indexed: 12/20/2022] Open
Abstract
Lectins are non-immunoglobulin carbohydrate-binding proteins without enzymatic activity towards the bound carbohydrates. Many lectins of e.g. plants or fungi have been suggested to act as toxins to defend the host against predators and parasites. We have previously shown that the Coprinopsis cinerea lectin 2 (CCL2), which binds to α1,3-fucosylated N-glycan cores, is toxic to Caenorhabditis elegans and results in developmental delay and premature death. In this study, we investigated the underlying toxicity phenotype at the cellular level by electron and confocal microscopy. We found that CCL2 directly binds to the intestinal apical surface and leads to a highly damaged brush border with loss of microvilli, actin filament depolymerization, and invaginations of the intestinal apical plasma membrane through gaps in the terminal web. We excluded several possible toxicity mechanisms such as internalization and pore-formation, suggesting that CCL2 acts directly on intestinal apical plasma membrane or glycocalyx proteins. A genetic screen for C. elegans mutants resistant to CCL2 generated over a dozen new alleles in bre 1, ger 1, and fut 1, three genes required for the synthesis of the sugar moiety recognized by CCL2. CCL2-induced intestinal brush border defects in C. elegans are similar to the damage observed previously in rats after feeding the dietary lectins wheat germ agglutinin or concanavalin A. The evolutionary conserved reaction of the brush border between mammals and nematodes might allow C. elegans to be exploited as model organism for the study of dietary lectin-induced intestinal pathology in mammals.
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Saegusa K, Sato M, Sato K, Nakajima-Shimada J, Harada A, Sato K. Caenorhabditis elegans chaperonin CCT/TRiC is required for actin and tubulin biogenesis and microvillus formation in intestinal epithelial cells. Mol Biol Cell 2014; 25:3095-104. [PMID: 25143409 PMCID: PMC4196862 DOI: 10.1091/mbc.e13-09-0530] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Intestinal epithelial cells have unique apical membrane structures, known as microvilli, that contain bundles of actin microfilaments. In this study, we report that Caenorhabditis elegans cytosolic chaperonin containing TCP-1 (CCT) is essential for proper formation of microvilli in intestinal cells. In intestinal cells of cct-5(RNAi) animals, a substantial amount of actin is lost from the apical area, forming large aggregates in the cytoplasm, and the apical membrane is deformed into abnormal, bubble-like structures. The length of the intestinal microvilli is decreased in these animals. However, the overall actin protein levels remain relatively unchanged when CCT is depleted. We also found that CCT depletion causes a reduction in the tubulin levels and disorganization of the microtubule network. In contrast, the stability and localization of intermediate filament protein IFB-2, which forms a dense filamentous network underneath the apical surface, appears to be superficially normal in CCT-deficient cells, suggesting substrate specificity of CCT in the folding of filamentous cytoskeletons in vivo. Our findings demonstrate physiological functions of CCT in epithelial cell morphogenesis using whole animals.
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Affiliation(s)
- Keiko Saegusa
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Miyuki Sato
- Laboratory of Molecular Membrane Biology, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Katsuya Sato
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | | | - Akihiro Harada
- Department of Cell Biology, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Ken Sato
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
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Lengerer B, Pjeta R, Wunderer J, Rodrigues M, Arbore R, Schärer L, Berezikov E, Hess MW, Pfaller K, Egger B, Obwegeser S, Salvenmoser W, Ladurner P. Biological adhesion of the flatworm Macrostomum lignano relies on a duo-gland system and is mediated by a cell type-specific intermediate filament protein. Front Zool 2014; 11:12. [PMID: 24520881 PMCID: PMC4016567 DOI: 10.1186/1742-9994-11-12] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 01/20/2014] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Free-living flatworms, in both marine and freshwater environments, are able to adhere to and release from a substrate several times within a second. This reversible adhesion relies on adhesive organs comprised of three cell types: an adhesive gland cell, a releasing gland cell, and an anchor cell, which is a modified epidermal cell responsible for structural support. However, nothing is currently known about the molecules that are involved in this adhesion process. RESULTS In this study we present the detailed morphology of the adhesive organs of the free-living marine flatworm Macrostomum lignano. About 130 adhesive organs are located in a horse-shoe-shaped arc along the ventral side of the tail plate. Each organ consists of exactly three cells, an adhesive gland cell, a releasing gland cell, and an anchor cell. The necks of the two gland cells penetrate the anchor cell through a common pore. Modified microvilli of the anchor cell form a collar surrounding the necks of the adhesive- and releasing glands, jointly forming the papilla, the outer visible part of the adhesive organs. Next, we identified an intermediate filament (IF) gene, macif1, which is expressed in the anchor cells. RNA interference mediated knock-down resulted in the first experimentally induced non-adhesion phenotype in any marine animal. Specifically, the absence of intermediate filaments in the anchor cells led to papillae with open tips, a reduction of the cytoskeleton network, a decline in hemidesmosomal connections, and to shortened microvilli containing less actin. CONCLUSION Our findings reveal an elaborate biological adhesion system in a free-living flatworm, which permits impressively rapid temporary adhesion-release performance in the marine environment. We demonstrate that the structural integrity of the supportive cell, the anchor cell, is essential for this adhesion process: the knock-down of the anchor cell-specific intermediate filament gene resulted in the inability of the animals to adhere. The RNAi mediated changes of the anchor cell morphology are comparable to situations observed in human gut epithelia. Therefore, our current findings and future investigations using this powerful flatworm model system might contribute to a better understanding of the function of intermediate filaments and their associated human diseases.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | - Peter Ladurner
- Institute of Zoology and Center of Molecular Bioscience Innsbruck, University of Innsbruck, Technikerstr, 25, Innsbruck A-6020, Austria.
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Kolotuev I, Hyenne V, Schwab Y, Rodriguez D, Labouesse M. A pathway for unicellular tube extension depending on the lymphatic vessel determinant Prox1 and on osmoregulation. Nat Cell Biol 2013; 15:157-68. [DOI: 10.1038/ncb2662] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Accepted: 11/26/2012] [Indexed: 01/14/2023]
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Karabinos A, Schünemann J, Parry DA. A rod domain sequence in segment 1B triggers dimerisation of the two small Branchiostoma IF proteins B2 and A3. Eur J Cell Biol 2012; 91:800-8. [PMID: 22878087 DOI: 10.1016/j.ejcb.2012.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 05/27/2012] [Accepted: 06/05/2012] [Indexed: 10/28/2022] Open
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Carberry K, Wiesenfahrt T, Geisler F, Stöcker S, Gerhardus H, Überbach D, Davis W, Jorgensen E, Leube RE, Bossinger O. The novel intestinal filament organizer IFO-1 contributes to epithelial integrity in concert with ERM-1 and DLG-1. Development 2012; 139:1851-62. [PMID: 22510987 DOI: 10.1242/dev.075788] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The nematode Caenorhabditis elegans is an excellent model system in which to study in vivo organization and function of the intermediate filament (IF) system for epithelial development and function. Using a transgenic ifb-2::cfp reporter strain, a mutagenesis screen was performed to identify mutants with aberrant expression patterns of the IF protein IFB-2, which is expressed in a dense network at the subapical endotube just below the microvillar brush border of intestinal cells. Two of the isolated alleles (kc2 and kc3) were mapped to the same gene, which we refer to as ifo-1 (intestinal filament organizer). The encoded polypeptide colocalizes with IF proteins and F-actin in the intestine. The apical localization of IFO-1 does not rely on IFB-2 but is dependent on LET-413, a basolateral protein involved in apical junction assembly and maintenance of cell polarity. In mutant worms, IFB-2 and IFC-2 are mislocalized in cytoplasmic granules and accumulate in large aggregates at the C. elegans apical junction (CeAJ) in a DLG-1-dependent fashion. Electron microscopy reveals loss of the prominent endotube and disordered but still intact microvilli. Semiquantitative fluorescence microscopy revealed a significant decrease of F-actin, suggesting a general role of IFO-1 in cytoskeletal organization. Furthermore, downregulation of the cytoskeletal organizer ERM-1 and the adherens junction component DLG-1, each of which leads to F-actin reduction on its own, induces a novel synthetic phenotype in ifo-1 mutants resulting in disruption of the lumen. We conclude that IFO-1 is a multipurpose linker between different cytoskeletal components of the C. elegans intestinal terminal web and contributes to proper epithelial tube formation.
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Affiliation(s)
- Katrin Carberry
- Institute of Molecular and Cellular Anatomy (MOCA), RWTH Aachen University, D-52074 Aachen, Germany
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Caenorhabditis elegans screen reveals role of PAR-5 in RAB-11-recycling endosome positioning and apicobasal cell polarity. Nat Cell Biol 2012; 14:666-76. [PMID: 22634595 DOI: 10.1038/ncb2508] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 04/19/2012] [Indexed: 02/08/2023]
Abstract
Apically enriched Rab11-positive recycling endosomes (Rab11-REs) are important for establishing and maintaining epithelial polarity. Yet, little is known about the molecules controlling trafficking of Rab11-REs in an epithelium in vivo. Here, we report a genome-wide, image-based RNA interference screen for regulators of Rab11-RE positioning and transport of an apical membrane protein (PEPT-1) in C. elegans intestine. Among the 356 screen hits was the 14-3-3 and partitioning defective protein PAR-5, which we found to be specifically required for Rab11-RE positioning and apicobasal polarity maintenance. Depletion of PAR-5 induced abnormal clustering of Rab11-REs to ectopic sites at the basolateral cortex containing F-actin and other apical domain components. This phenotype required key regulators of F-actin dynamics and polarity, such as Rho GTPases (RHO-1 and the Rac1 orthologue CED-10) and apical PAR proteins. Our data suggest that PAR-5 acts as a regulatory hub for a polarity-maintaining network required for apicobasal asymmetry of F-actin and proper Rab11-RE positioning.
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Non-lytic, actin-based exit of intracellular parasites from C. elegans intestinal cells. PLoS Pathog 2011; 7:e1002227. [PMID: 21949650 PMCID: PMC3174248 DOI: 10.1371/journal.ppat.1002227] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Accepted: 07/06/2011] [Indexed: 02/06/2023] Open
Abstract
The intestine is a common site for invasion by intracellular pathogens, but little is known about how pathogens restructure and exit intestinal cells in vivo. The natural microsporidian parasite N. parisii invades intestinal cells of the nematode C. elegans, progresses through its life cycle, and then exits cells in a transmissible spore form. Here we show that N. parisii causes rearrangements of host actin inside intestinal cells as part of a novel parasite exit strategy. First, we show that N. parisii infection causes ectopic localization of the normally apical-restricted actin to the basolateral side of intestinal cells, where it often forms network-like structures. Soon after this actin relocalization, we find that gaps appear in the terminal web, a conserved cytoskeletal structure that could present a barrier to exit. Reducing actin expression creates terminal web gaps in the absence of infection, suggesting that infection-induced actin relocalization triggers gap formation. We show that terminal web gaps form at a distinct stage of infection, precisely timed to precede spore exit, and that all contagious animals exhibit gaps. Interestingly, we find that while perturbations in actin can create these gaps, actin is not required for infection progression or spore formation, but actin is required for spore exit. Finally, we show that despite large numbers of spores exiting intestinal cells, this exit does not cause cell lysis. These results provide insight into parasite manipulation of the host cytoskeleton and non-lytic escape from intestinal cells in vivo. The intestine is a common site for invasion by pathogens, but little is known about how pathogens exit out of live intestinal cells in order to spread and propagate. One group of parasites that often invades the intestine is the microsporidia, which comprise a phylum of over 1200 fungal-like species that can cause disease in humans, as well as in agriculturally significant organisms such as fish, silkworm and honey bee. Here, we investigated a natural microsporidian infection in live intestinal cells of the roundworm C. elegans. We discovered a novel exit strategy used by microsporidia to restructure the cytoskeleton of intestinal cells, involving relocalization of actin and reorganization of a structure called the terminal web, which may be a barrier to exit. In addition, we found that despite large numbers of parasites exiting out of intestinal cells, this process does not cause cells to burst. Our findings indicate that microsporidia, which are completely dependent on their hosts for replication, have evolved a regulated and non-damaging mechanism of exit that shares similarities with strategies used by evolutionarily distant bacterial pathogens. This study provides new insights into the methods by which pathogens restructure live intestinal cells to facilitate their spread and propagation.
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Synaptogyrin-dependent modulation of synaptic neurotransmission in Caenorhabditis elegans. Neuroscience 2011; 190:75-88. [DOI: 10.1016/j.neuroscience.2011.05.069] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 05/20/2011] [Accepted: 05/28/2011] [Indexed: 01/31/2023]
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Mencarelli C, Ciolfi S, Caroti D, Lupetti P, Dallai R. Isomin: a novel cytoplasmic intermediate filament protein from an arthropod species. BMC Biol 2011; 9:17. [PMID: 21356109 PMCID: PMC3065449 DOI: 10.1186/1741-7007-9-17] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 02/28/2011] [Indexed: 11/10/2022] Open
Abstract
Background The expression of intermediate filaments (IFs) is a hallmark feature of metazoan cells. IFs play a central role in cell organization and function, acting mainly as structural stress-absorbing elements. There is growing evidence to suggest that these cytoskeletal elements are also involved in the integration of signalling networks. According to their fundamental functions, IFs show a widespread phylogenetic expression, from simple diblastic animals up to mammals, and their constituent proteins share the same molecular organization in all species so far analysed. Arthropods represent a major exception in this scenario. Only lamins, the nuclear IF proteins, have so far been identified in the model organisms analysed; on this basis, it has been considered that arthropods do not express cytoplasmic IFs. Results Here, we report the first evidence for the expression of a cytoplasmic IF protein in an arthropod - the basal hexapod Isotomurus maculatus. This new protein, we named it isomin, is a component of the intestinal terminal web and shares with IFs typical biochemical properties, molecular features and reassembly capability. Sequence analysis indicates that isomin is mostly related to the Intermediate Filament protein C (IFC) subfamily of Caenorhabditis elegans IF proteins, which are molecular constituents of the nematode intestinal terminal web. This finding is coherent with, and provides further support to, the most recent phylogenetic views of arthropod ancestry. Interestingly, the coil 1a domain of isomin appears to have been influenced by a substantial molecular drift and only the aminoterminal part of this domain, containing the so-called helix initiation motif, has been conserved. Conclusions Our results set a new basis for the analysis of IF protein evolution during arthropod phylogeny. In the light of this new information, the statement that the arthropod phylum lacks cytoplasmic IFs is no longer tenable. See commentary article: http://www.biomedcentral.com/1741-7007-9-16.
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Affiliation(s)
- Caterina Mencarelli
- Department of Evolutionary Biology, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy.
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Félix MA, Ashe A, Piffaretti J, Wu G, Nuez I, Bélicard T, Jiang Y, Zhao G, Franz CJ, Goldstein LD, Sanroman M, Miska EA, Wang D. Natural and experimental infection of Caenorhabditis nematodes by novel viruses related to nodaviruses. PLoS Biol 2011; 9:e1000586. [PMID: 21283608 PMCID: PMC3026760 DOI: 10.1371/journal.pbio.1000586] [Citation(s) in RCA: 257] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Accepted: 12/10/2010] [Indexed: 01/01/2023] Open
Abstract
An ideal model system to study antiviral immunity and host-pathogen co-evolution would combine a genetically tractable small animal with a virus capable of naturally infecting the host organism. The use of C. elegans as a model to define host-viral interactions has been limited by the lack of viruses known to infect nematodes. From wild isolates of C. elegans and C. briggsae with unusual morphological phenotypes in intestinal cells, we identified two novel RNA viruses distantly related to known nodaviruses, one infecting specifically C. elegans (Orsay virus), the other C. briggsae (Santeuil virus). Bleaching of embryos cured infected cultures demonstrating that the viruses are neither stably integrated in the host genome nor transmitted vertically. 0.2 µm filtrates of the infected cultures could infect cured animals. Infected animals continuously maintained viral infection for 6 mo (∼50 generations), demonstrating that natural cycles of horizontal virus transmission were faithfully recapitulated in laboratory culture. In addition to infecting the natural C. elegans isolate, Orsay virus readily infected laboratory C. elegans mutants defective in RNAi and yielded higher levels of viral RNA and infection symptoms as compared to infection of the corresponding wild-type N2 strain. These results demonstrated a clear role for RNAi in the defense against this virus. Furthermore, different wild C. elegans isolates displayed differential susceptibility to infection by Orsay virus, thereby affording genetic approaches to defining antiviral loci. This discovery establishes a bona fide viral infection system to explore the natural ecology of nematodes, host-pathogen co-evolution, the evolution of small RNA responses, and innate antiviral mechanisms.
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Affiliation(s)
- Marie-Anne Félix
- Institut Jacques Monod, CNRS-University of Paris-Diderot, Paris, France
| | - Alyson Ashe
- Gurdon Institute, University of Cambridge, Cambridge, United Kingdom
| | | | - Guang Wu
- Departments of Molecular Microbiology and Pathology & Immunology, Washington University in St. Louis School of Medicine, St. Louis, Missouri, United States of America
| | - Isabelle Nuez
- Institut Jacques Monod, CNRS-University of Paris-Diderot, Paris, France
| | - Tony Bélicard
- Institut Jacques Monod, CNRS-University of Paris-Diderot, Paris, France
| | - Yanfang Jiang
- Departments of Molecular Microbiology and Pathology & Immunology, Washington University in St. Louis School of Medicine, St. Louis, Missouri, United States of America
| | - Guoyan Zhao
- Departments of Molecular Microbiology and Pathology & Immunology, Washington University in St. Louis School of Medicine, St. Louis, Missouri, United States of America
| | - Carl J. Franz
- Departments of Molecular Microbiology and Pathology & Immunology, Washington University in St. Louis School of Medicine, St. Louis, Missouri, United States of America
| | | | - Mabel Sanroman
- Institut Jacques Monod, CNRS-University of Paris-Diderot, Paris, France
| | - Eric A. Miska
- Gurdon Institute, University of Cambridge, Cambridge, United Kingdom
| | - David Wang
- Departments of Molecular Microbiology and Pathology & Immunology, Washington University in St. Louis School of Medicine, St. Louis, Missouri, United States of America
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Hoffmann M, Segbert C, Helbig G, Bossinger O. Intestinal tube formation in Caenorhabditis elegans requires vang-1 and egl-15 signaling. Dev Biol 2010; 339:268-79. [DOI: 10.1016/j.ydbio.2009.12.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Revised: 11/26/2009] [Accepted: 12/01/2009] [Indexed: 10/20/2022]
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Carberry K, Wiesenfahrt T, Windoffer R, Bossinger O, Leube RE. Intermediate filaments in Caenorhabditis elegans. ACTA ACUST UNITED AC 2009; 66:852-64. [PMID: 19437512 DOI: 10.1002/cm.20372] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Intermediate filaments (IFs) make up one of the three major fibrous cytoskeletal systems in metazoans. Numerous IF polypeptides are synthesized in cell type-specific combinations suggesting specialized functions. The review concentrates on IFs in the model organism Caenorhabditis elegans which carries great promise to elucidate the still unresolved mechanisms of IF assembly into complex networks and to determine IF function in a living organism. In contrast to Drosophila melanogaster, which lacks cytoplasmic IFs altogether, the nematode genome contains 11 genes coding for cytoplasmic IFs and only a single gene for a nuclear lamin. Its cytoplasmic IFs are expressed in developmentally and spatially defined patterns. As an example we present the case of the intestinal IFs which are abundant in the mechanically resilient endotube, a prominent feature of the C. elegans intestinal terminal web region. This IF-rich structure brings together all three cytoskeletal filaments that are integrated into a coherent entity by the C. elegans apical junction (CeAJ) thereby completely surrounding and stabilizing the intestinal lumen with its characteristic brush border. Concepts on the developmental establishment of the endotube in relation to polarization and its function for maintenance of epithelial integrity are discussed. Furthermore, possible connections of the cytoplasmic cytoskeleton to the nuclear lamin IFs and the importance of these links for nuclear positioning are summarized.
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Affiliation(s)
- Katrin Carberry
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, 52074 Aachen, Germany
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Vijayaraj P, Kröger C, Reuter U, Windoffer R, Leube RE, Magin TM. Keratins regulate protein biosynthesis through localization of GLUT1 and -3 upstream of AMP kinase and Raptor. ACTA ACUST UNITED AC 2009; 187:175-84. [PMID: 19841136 PMCID: PMC2768834 DOI: 10.1083/jcb.200906094] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Removal of the entire keratin family of intermediate filament proteins from embryonic epithelia has surprising implications for mTOR signaling. Keratin intermediate filament proteins form cytoskeletal scaffolds in epithelia, the disruption of which affects cytoarchitecture, cell growth, survival, and organelle transport. However, owing to redundancy, the global function of keratins has not been defined in full. Using a targeted gene deletion strategy, we generated transgenic mice lacking the entire keratin multiprotein family. In this study, we report that without keratins, embryonic epithelia suffer no cytolysis and maintain apical polarity but display mislocalized desmosomes. All keratin-null embryos die from severe growth retardation at embryonic day 9.5. We find that GLUT1 and -3 are mislocalized from the apical plasma membrane in embryonic epithelia, which subsequently activates the energy sensor adenosine monophosphate kinase (AMPK). Analysis of the mammalian target of rapamycin (mTOR) pathway reveals that AMPK induction activates Raptor, repressing protein biosynthesis through mTORC1's downstream targets S6 kinase and 4E-binding protein 1. Our findings demonstrate a novel keratin function upstream of mTOR signaling via GLUT localization and have implications for pathomechanisms and therapy approaches for keratin disorders and the analysis of other gene families.
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Affiliation(s)
- Preethi Vijayaraj
- Abteilung für Zellbiochemie, Institut für Biochemie und Molekularbiologie and 2 Bonner Forum Biomedizin, Universität Bonn, 53115 Bonn, Germany
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