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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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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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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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Sukhotnik I, Shahar YB, Pollak Y, Dorfman T, Shefer HK, Assi ZE, Mor-Vaknin N, Coran AG. The role of intermediate filaments in maintaining integrity and function of intestinal epithelial cells after massive bowel resection in a rat. Pediatr Surg Int 2018; 34:217-225. [PMID: 29043445 DOI: 10.1007/s00383-017-4192-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/21/2017] [Indexed: 01/22/2023]
Abstract
PURPOSE Intermediate filaments (IFs) are a part of the cytoskeleton that extend throughout the cytoplasm of all cells and function in the maintenance of cell-shape by bearing tension and serving as structural components of the nuclear lamina. In normal intestine, IFs provide a tissue-specific three-dimensional scaffolding with unique context-dependent organizational features. The purpose of this study was to evaluate the role of IFs during intestinal adaptation in a rat model of short bowel syndrome (SBS). MATERIALS AND METHODS Male rats were divided into two groups: Sham rats underwent bowel transection and SBS rats underwent a 75% bowel resection. Parameters of intestinal adaptation, enterocyte proliferation and apoptosis were determined 2 weeks after operation. Illumina's Digital Gene Expression (DGE) analysis was used to determine the cytoskeleton-related gene expression profiling. IF-related genes and protein expression were determined using real-time PCR, Western blotting and immunohistochemistry. RESULTS Massive small bowel resection resulted in a significant increase in enterocyte proliferation and concomitant increase in cell apoptosis. From the total number of 20,000 probes, 16 cytoskeleton-related genes were investigated. Between these genes, only myosin and tubulin levels were upregulated in SBS compared to sham animals. Between IF-related genes, desmin, vimentin and lamin levels were down-regulated and keratin and neurofilament remain unchanged. The levels of TGF-β, vimentin and desmin gene and protein were down-regulated in resected rats (vs sham animals). CONCLUSIONS Two weeks following massive bowel resection in rats, the accelerated cell turnover was accompanied by a stimulated microfilaments and microtubules, and by inhibited intermediate filaments. Resistance to cell compression rather that maintenance of cell-shape by bearing tension are responsible for contraction, motility and postmitotic cell separation in a late stage of intestinal adaptation.
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Affiliation(s)
- I Sukhotnik
- Laboratory of Intestinal Adaptation and Recovery, The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
- Department of Pediatric Surgery, Bnai Zion Medical Center, Golomb St., P.O.B. 4940, 31048, Haifa, Israel.
| | - Y Ben Shahar
- Laboratory of Intestinal Adaptation and Recovery, The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
- Department of Pediatric Surgery, Bnai Zion Medical Center, Golomb St., P.O.B. 4940, 31048, Haifa, Israel
| | - Y Pollak
- Laboratory of Intestinal Adaptation and Recovery, The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - T Dorfman
- Laboratory of Intestinal Adaptation and Recovery, The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - H Kreizman Shefer
- Laboratory of Intestinal Adaptation and Recovery, The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Z E Assi
- Laboratory of Intestinal Adaptation and Recovery, The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
- Department of Pediatric Surgery, Bnai Zion Medical Center, Golomb St., P.O.B. 4940, 31048, Haifa, Israel
| | - N Mor-Vaknin
- Department of Internal Medicine, C.S. Mott Children's Hospital, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - A G Coran
- Section of Pediatric Surgery, C.S. Mott Children's Hospital, University of Michigan Medical School, Ann Arbor, Michigan, USA
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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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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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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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