1
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Ernst C, Andreassen PR, Giger GH, Nguyen BD, Gäbelein CG, Guillaume-Gentil O, Fattinger SA, Sellin ME, Hardt WD, Vorholt JA. Direct Salmonella injection into enteroid cells allows the study of host-pathogen interactions in the cytosol with high spatiotemporal resolution. PLoS Biol 2024; 22:e3002597. [PMID: 38684033 PMCID: PMC11057982 DOI: 10.1371/journal.pbio.3002597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 03/21/2024] [Indexed: 05/02/2024] Open
Abstract
Intestinal epithelial cells (IECs) play pivotal roles in nutrient uptake and in the protection against gut microorganisms. However, certain enteric pathogens, such as Salmonella enterica serovar Typhimurium (S. Tm), can invade IECs by employing flagella and type III secretion systems (T3SSs) with cognate effector proteins and exploit IECs as a replicative niche. Detection of flagella or T3SS proteins by IECs results in rapid host cell responses, i.e., the activation of inflammasomes. Here, we introduce a single-cell manipulation technology based on fluidic force microscopy (FluidFM) that enables direct bacteria delivery into the cytosol of single IECs within a murine enteroid monolayer. This approach allows to specifically study pathogen-host cell interactions in the cytosol uncoupled from preceding events such as docking, initiation of uptake, or vacuole escape. Consistent with current understanding, we show using a live-cell inflammasome reporter that exposure of the IEC cytosol to S. Tm induces NAIP/NLRC4 inflammasomes via its known ligands flagellin and T3SS rod and needle. Injected S. Tm mutants devoid of these invasion-relevant ligands were able to grow in the cytosol of IECs despite the absence of T3SS functions, suggesting that, in the absence of NAIP/NLRC4 inflammasome activation and the ensuing cell death, no effector-mediated host cell manipulation is required to render the epithelial cytosol growth-permissive for S. Tm. Overall, the experimental system to introduce S. Tm into single enteroid cells enables investigations into the molecular basis governing host-pathogen interactions in the cytosol with high spatiotemporal resolution.
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Affiliation(s)
- Chantal Ernst
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | | | - Gabriel H. Giger
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Bidong D. Nguyen
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | | | | | - Stefan A. Fattinger
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Mikael E. Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Julia A. Vorholt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
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2
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Bergman S, Andresen L, Kjellin J, Martinez Burgo Y, Geiser P, Baars S, Söderbom F, Sellin ME, Holmqvist E. ProQ-dependent activation of Salmonella virulence genes mediated by post-transcriptional control of PhoP synthesis. mSphere 2024; 9:e0001824. [PMID: 38411119 PMCID: PMC10964419 DOI: 10.1128/msphere.00018-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 02/06/2024] [Indexed: 02/28/2024] Open
Abstract
Gastrointestinal disease caused by Salmonella enterica is associated with the pathogen's ability to replicate within epithelial cells and macrophages. Upon host cell entry, the bacteria express a type-three secretion system encoded within Salmonella pathogenicity island 2, through which host-manipulating effector proteins are secreted to establish a stable intracellular niche. Transcription of this intracellular virulence program is activated by the PhoPQ two-component system that senses the low pH and the reduced magnesium concentration of host cell vacuoles. In addition to transcriptional control, Salmonella commonly employ RNA-binding proteins (RBPs) and small regulatory RNAs (sRNAs) to regulate gene expression at the post-transcriptional level. ProQ is a globally acting RBP in Salmonella that promotes expression of the intracellular virulence program, but its RNA repertoire has previously been characterized only under standard laboratory growth conditions. Here, we provide a high-resolution ProQ interactome during conditions mimicking the environment of the Salmonella-containing vacuole (SCV), revealing hundreds of previously unknown ProQ binding sites in sRNAs and mRNA 3'UTRs. ProQ positively affected both the levels and the stability of many sRNA ligands, some of which were previously shown to associate with the well-studied and infection-relevant RBP Hfq. We further show that ProQ activates the expression of PhoP at the post-transcriptional level, which, in turn, leads to upregulation of the intracellular virulence program. IMPORTANCE Salmonella enterica is a major pathogen responsible for foodborne gastroenteritis, and a leading model organism for genetic and molecular studies of bacterial virulence mechanisms. One key trait of this pathogen is the ability to survive within infected host cells. During infection, the bacteria employ a type three secretion system that deliver effector proteins to target and manipulate host cell processes. The transcriptional regulation of this virulence program is well understood. By contrast, the factors and mechanisms operating at the post-transcriptional level to control virulence gene expression are less clear. In this study, we have charted the global RNA ligand repertoire of the RNA-binding protein ProQ during in vitro conditions mimicking the host cell environment. This identified hundreds of binding sites and revealed ProQ-dependent stabilization of intracellular-specific small RNAs. Importantly, we show that ProQ post-transcriptionally activates the expression of PhoP, a master transcriptional activator of intracellular virulence in Salmonella.
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Affiliation(s)
- Sofia Bergman
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Liis Andresen
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Jonas Kjellin
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Yolanda Martinez Burgo
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Petra Geiser
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Sophie Baars
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Fredrik Söderbom
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Mikael E. Sellin
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Erik Holmqvist
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, Sweden
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3
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Gül E, Huuskonen J, Abi Younes A, Maurer L, Enz U, Zimmermann J, Sellin ME, Bakkeren E, Hardt WD. Salmonella T3SS-2 virulence enhances gut-luminal colonization by enabling chemotaxis-dependent exploitation of intestinal inflammation. Cell Rep 2024; 43:113925. [PMID: 38460128 DOI: 10.1016/j.celrep.2024.113925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 01/12/2024] [Accepted: 02/20/2024] [Indexed: 03/11/2024] Open
Abstract
Salmonella Typhimurium (S.Tm) utilizes the chemotaxis receptor Tsr to exploit gut inflammation. However, the characteristics of this exploitation and the mechanism(s) employed by the pathogen to circumvent antimicrobial effects of inflammation are poorly defined. Here, using different naturally occurring S.Tm strains (SL1344 and 14028) and competitive infection experiments, we demonstrate that type-three secretion system (T3SS)-2 virulence is indispensable for the beneficial effects of Tsr-directed chemotaxis. The removal of the 14028-specific prophage Gifsy3, encoding virulence effectors, results in the loss of the Tsr-mediated fitness advantage in that strain. Surprisingly, without T3SS-2 effector secretion, chemotaxis toward the gut epithelium using Tsr becomes disadvantageous for either strain. Our findings reveal that luminal neutrophils recruited as a result of NLRC4 inflammasome activation locally counteract S.Tm cells exploiting the byproducts of the host immune response. This work highlights a mechanism by which S.Tm exploitation of gut inflammation for colonization relies on the coordinated effects of chemotaxis and T3SS activities.
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Affiliation(s)
- Ersin Gül
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland.
| | - Jemina Huuskonen
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Andrew Abi Younes
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Luca Maurer
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Ursina Enz
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Jakob Zimmermann
- Department of Visceral Surgery and Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland; Department for Biomedical Research, University of Bern, Bern, Switzerland
| | - Mikael E Sellin
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden; Science for Life Laboratory, Uppsala, Sweden
| | - Erik Bakkeren
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland.
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4
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Hellman S, Martin F, Tydén E, Sellin ME, Norman A, Hjertner B, Svedberg P, Fossum C. Equine enteroid-derived monolayers recapitulate key features of parasitic intestinal nematode infection. Vet Res 2024; 55:25. [PMID: 38414039 PMCID: PMC10900620 DOI: 10.1186/s13567-024-01266-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Accepted: 01/03/2024] [Indexed: 02/29/2024] Open
Abstract
Stem cell-derived organoid cultures have emerged as attractive experimental models for infection biology research regarding various types of gastro-intestinal pathogens and host species. However, the large size of infectious nematode larvae and the closed structure of 3-dimensional organoids often hinder studies of the natural route of infection. To enable easy administration to the apical surface of the epithelium, organoids from the equine small intestine, i.e. enteroids, were used in the present study to establish epithelial monolayer cultures. These monolayers were functionally tested by stimulation with IL-4 and IL-13, and/or exposure to infectious stage larvae of the equine nematodes Parascaris univalens, cyathostominae and/or Strongylus vulgaris. Effects were recorded using transcriptional analysis combined with histochemistry, immunofluorescence-, live-cell- and scanning electron microscopy. These analyses revealed heterogeneous monolayers containing both immature and differentiated cells including tuft cells and mucus-producing goblet cells. Stimulation with IL-4/IL-13 increased tuft- and goblet cell differentiation as demonstrated by the expression of DCLK1 and MUC2. In these cytokine-primed monolayers, the expression of MUC2 was further promoted by co-culture with P. univalens. Moreover, live-cell imaging revealed morphological alterations of the epithelial cells following exposure to larvae even in the absence of cytokine stimulation. Thus, the present work describes the design, characterization and usability of an experimental model representing the equine nematode-infected small intestinal epithelium. The presence of tuft cells and goblet cells whose mucus production is affected by Th2 cytokines and/or the presence of larvae opens up for mechanistic studies of the physical interactions between nematodes and the equine intestinal mucosa.
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Affiliation(s)
- Stina Hellman
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, SLU, P.O. Box 7028, 750 07, Uppsala, Sweden.
| | - Frida Martin
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, SLU, P.O. Box 7028, 750 07, Uppsala, Sweden
| | - Eva Tydén
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, SLU, P.O. Box 7028, 750 07, Uppsala, Sweden
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Albin Norman
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, SLU, P.O. Box 7028, 750 07, Uppsala, Sweden
| | - Bernt Hjertner
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, SLU, P.O. Box 7028, 750 07, Uppsala, Sweden
| | - Pia Svedberg
- Vidilab AB, P.O. Box 33, 745 21, Enköping, Sweden
| | - Caroline Fossum
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, SLU, P.O. Box 7028, 750 07, Uppsala, Sweden
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5
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von Beek C, Fahlgren A, Geiser P, Di Martino ML, Lindahl O, Prensa GI, Mendez-Enriquez E, Eriksson J, Hallgren J, Fällman M, Pejler G, Sellin ME. A two-step activation mechanism enables mast cells to differentiate their response between extracellular and invasive enterobacterial infection. Nat Commun 2024; 15:904. [PMID: 38291037 PMCID: PMC10828507 DOI: 10.1038/s41467-024-45057-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 01/12/2024] [Indexed: 02/01/2024] Open
Abstract
Mast cells localize to mucosal tissues and contribute to innate immune defense against infection. How mast cells sense, differentiate between, and respond to bacterial pathogens remains a topic of ongoing debate. Using the prototype enteropathogen Salmonella Typhimurium (S.Tm) and other related enterobacteria, here we show that mast cells can regulate their cytokine secretion response to distinguish between extracellular and invasive bacterial infection. Tissue-invasive S.Tm and mast cells colocalize in the mouse gut during acute Salmonella infection. Toll-like Receptor 4 (TLR4) sensing of extracellular S.Tm, or pure lipopolysaccharide, causes a modest induction of cytokine transcripts and proteins, including IL-6, IL-13, and TNF. By contrast, type-III-secretion-system-1 (TTSS-1)-dependent S.Tm invasion of both mouse and human mast cells triggers rapid and potent inflammatory gene expression and >100-fold elevated cytokine secretion. The S.Tm TTSS-1 effectors SopB, SopE, and SopE2 here elicit a second activation signal, including Akt phosphorylation downstream of effector translocation, which combines with TLR activation to drive the full-blown mast cell response. Supernatants from S.Tm-infected mast cells boost macrophage survival and maturation from bone-marrow progenitors. Taken together, this study shows that mast cells can differentiate between extracellular and host-cell invasive enterobacteria via a two-step activation mechanism and tune their inflammatory output accordingly.
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Affiliation(s)
- Christopher von Beek
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Anna Fahlgren
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Petra Geiser
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | | | - Otto Lindahl
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Grisna I Prensa
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Erika Mendez-Enriquez
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Jens Eriksson
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Jenny Hallgren
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Maria Fällman
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Gunnar Pejler
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
| | - Mikael E Sellin
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
- Science for Life Laboratory, Uppsala, Sweden.
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6
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Fattinger SA, Maurer L, Geiser P, Bernard EM, Enz U, Ganguillet S, Gül E, Kroon S, Demarco B, Mack V, Furter M, Barthel M, Pelczar P, Shao F, Broz P, Sellin ME, Hardt WD. Gasdermin D is the only Gasdermin that provides protection against acute Salmonella gut infection in mice. Proc Natl Acad Sci U S A 2023; 120:e2315503120. [PMID: 37988464 PMCID: PMC10691232 DOI: 10.1073/pnas.2315503120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/05/2023] [Indexed: 11/23/2023] Open
Abstract
Gasdermins (GSDMs) share a common functional domain structure and are best known for their capacity to form membrane pores. These pores are hallmarks of a specific form of cell death called pyroptosis and mediate the secretion of pro-inflammatory cytokines such as interleukin 1β (IL1β) and interleukin 18 (IL18). Thereby, Gasdermins have been implicated in various immune responses against cancer and infectious diseases such as acute Salmonella Typhimurium (S.Tm) gut infection. However, to date, we lack a comprehensive functional assessment of the different Gasdermins (GSDMA-E) during S.Tm infection in vivo. Here, we used epithelium-specific ablation, bone marrow chimeras, and mouse lines lacking individual Gasdermins, combinations of Gasdermins or even all Gasdermins (GSDMA1-3C1-4DE) at once and performed littermate-controlled oral S.Tm infections in streptomycin-pretreated mice to investigate the impact of all murine Gasdermins. While GSDMA, C, and E appear dispensable, we show that GSDMD i) restricts S.Tm loads in the gut tissue and systemic organs, ii) controls gut inflammation kinetics, and iii) prevents epithelium disruption by 72 h of the infection. Full protection requires GSDMD expression by both bone-marrow-derived lamina propria cells and intestinal epithelial cells (IECs). In vivo experiments as well as 3D-, 2D-, and chimeric enteroid infections further show that infected IEC extrusion proceeds also without GSDMD, but that GSDMD controls the permeabilization and morphology of the extruding IECs, affects extrusion kinetics, and promotes overall mucosal barrier capacity. As such, this work identifies a unique multipronged role of GSDMD among the Gasdermins for mucosal tissue defense against a common enteric pathogen.
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Affiliation(s)
- Stefan A. Fattinger
- Department of Biology, Institute of Microbiology, ETH Zurich, Zurich8093, Switzerland
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala75123, Sweden
- Division of Immunology and Molecular Medicine, Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
| | - Luca Maurer
- Department of Biology, Institute of Microbiology, ETH Zurich, Zurich8093, Switzerland
| | - Petra Geiser
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala75123, Sweden
| | - Elliott M. Bernard
- Department of Immunobiology, University of Lausanne, Epalinges1066, Switzerland
| | - Ursina Enz
- Department of Biology, Institute of Microbiology, ETH Zurich, Zurich8093, Switzerland
| | - Suwannee Ganguillet
- Department of Biology, Institute of Microbiology, ETH Zurich, Zurich8093, Switzerland
| | - Ersin Gül
- Department of Biology, Institute of Microbiology, ETH Zurich, Zurich8093, Switzerland
| | - Sanne Kroon
- Department of Biology, Institute of Microbiology, ETH Zurich, Zurich8093, Switzerland
| | - Benjamin Demarco
- Department of Immunobiology, University of Lausanne, Epalinges1066, Switzerland
| | - Vanessa Mack
- Department of Immunobiology, University of Lausanne, Epalinges1066, Switzerland
| | - Markus Furter
- Department of Biology, Institute of Microbiology, ETH Zurich, Zurich8093, Switzerland
| | - Manja Barthel
- Department of Biology, Institute of Microbiology, ETH Zurich, Zurich8093, Switzerland
| | - Pawel Pelczar
- Center for Transgenic Models, University of Basel, Basel4002, Switzerland
| | - Feng Shao
- National Institute of Biological Sciences, Beijing102206, China
| | - Petr Broz
- Department of Immunobiology, University of Lausanne, Epalinges1066, Switzerland
| | - Mikael E. Sellin
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala75123, Sweden
| | - Wolf-Dietrich Hardt
- Department of Biology, Institute of Microbiology, ETH Zurich, Zurich8093, Switzerland
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7
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Gül E, Fattinger SA, Sellin ME, Hardt WD. Epithelial inflammasomes, gasdermins, and mucosal inflammation - Lessons from Salmonella and Shigella infected mice. Semin Immunol 2023; 70:101812. [PMID: 37562110 DOI: 10.1016/j.smim.2023.101812] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/05/2023] [Accepted: 07/15/2023] [Indexed: 08/12/2023]
Abstract
Besides its crucial function in nutrient absorbance and as barrier against the microbiota, the gut epithelium is essential for sensing pathogenic insults and mounting of an appropriate early immune response. In mice, the activation of the canonical NAIP/NLRC4 inflammasome is critical for the defense against enterobacterial infections. Activation of the NAIP/NLRC4 inflammasome triggers the extrusion of infected intestinal epithelial cells (IEC) into the gut lumen, concomitant with inflammasome-mediated lytic cell death. The membrane permeabilization, a hallmark of pyroptosis, is caused by the pore-forming proteins called gasdermins (GSDMs). Recent work has revealed that NAIP/NLRC4-dependent extrusion of infected IECs can, however, also be executed in the absence of GSDMD. In fact, several reports highlighted that various cell death pathways (e.g., pyroptosis or apoptosis) and unique mechanisms specific to particular infection models and stages of gut infection are in action during epithelial inflammasome defense against intestinal pathogens. Here, we summarize the current knowledge regarding the underlying mechanisms and speculate on the putative functions of the epithelial inflammasome activation and cell death, with a particular emphasis on mouse infection models for two prominent enterobacterial pathogens, Salmonella Typhimurium and Shigella flexneri.
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Affiliation(s)
- Ersin Gül
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Stefan A Fattinger
- Division of Immunology and Molecular Medicine, Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland.
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8
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Gül E, Enz U, Maurer L, Abi Younes A, Fattinger SA, Nguyen BD, Hausmann A, Furter M, Barthel M, Sellin ME, Hardt WD. Intraluminal neutrophils limit epithelium damage by reducing pathogen assault on intestinal epithelial cells during Salmonella gut infection. PLoS Pathog 2023; 19:e1011235. [PMID: 37384776 DOI: 10.1371/journal.ppat.1011235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 06/14/2023] [Indexed: 07/01/2023] Open
Abstract
Recruitment of neutrophils into and across the gut mucosa is a cardinal feature of intestinal inflammation in response to enteric infections. Previous work using the model pathogen Salmonella enterica serovar Typhimurium (S.Tm) established that invasion of intestinal epithelial cells by S.Tm leads to recruitment of neutrophils into the gut lumen, where they can reduce pathogen loads transiently. Notably, a fraction of the pathogen population can survive this defense, re-grow to high density, and continue triggering enteropathy. However, the functions of intraluminal neutrophils in the defense against enteric pathogens and their effects on preventing or aggravating epithelial damage are still not fully understood. Here, we address this question via neutrophil depletion in different mouse models of Salmonella colitis, which differ in their degree of enteropathy. In an antibiotic pretreated mouse model, neutrophil depletion by an anti-Ly6G antibody exacerbated epithelial damage. This could be linked to compromised neutrophil-mediated elimination and reduced physical blocking of the gut-luminal S.Tm population, such that the pathogen density remained high near the epithelial surface throughout the infection. Control infections with a ssaV mutant and gentamycin-mediated elimination of gut-luminal pathogens further supported that neutrophils are protecting the luminal surface of the gut epithelium. Neutrophil depletion in germ-free and gnotobiotic mice hinted that the microbiota can modulate the infection kinetics and ameliorate epithelium-disruptive enteropathy even in the absence of neutrophil-protection. Together, our data indicate that the well-known protective effect of the microbiota is augmented by intraluminal neutrophils. After antibiotic-mediated microbiota disruption, neutrophils are central for maintaining epithelial barrier integrity during acute Salmonella-induced gut inflammation, by limiting the sustained pathogen assault on the epithelium in a critical window of the infection.
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Affiliation(s)
- Ersin Gül
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Ursina Enz
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Luca Maurer
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Andrew Abi Younes
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Stefan A Fattinger
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Bidong D Nguyen
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Annika Hausmann
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Markus Furter
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Manja Barthel
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
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9
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Kaur A, Lin W, Dovhalyuk V, Driutti L, Di Martino ML, Vujasinovic M, Löhr JM, Sellin ME, Globisch D. Chemoselective bicyclobutane-based mass spectrometric detection of biological thiols uncovers human and bacterial metabolites. Chem Sci 2023; 14:5291-5301. [PMID: 37234898 PMCID: PMC10207876 DOI: 10.1039/d3sc00224a] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 04/05/2023] [Indexed: 05/28/2023] Open
Abstract
Sulfur is an essential element of life. Thiol-containing metabolites in all organisms are involved in the regulation of diverse biological processes. Especially, the microbiome produces bioactive metabolites or biological intermediates of this compound class. The analysis of thiol-containing metabolites is challenging due to the lack of specific tools, making these compounds difficult to investigate selectively. We have now developed a new methodology comprising bicyclobutane for chemoselective and irreversible capturing of this metabolite class. We utilized this new chemical biology tool immobilized onto magnetic beads for the investigation of human plasma, fecal samples, and bacterial cultures. Our mass spectrometric investigation detected a broad range of human, dietary and bacterial thiol-containing metabolites and we even captured the reactive sulfur species cysteine persulfide in both fecal and bacterial samples. The described comprehensive methodology represents a new mass spectrometric strategy for the discovery of bioactive thiol-containing metabolites in humans and the microbiome.
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Affiliation(s)
- Amanpreet Kaur
- Department of Chemistry - BMC, Science for Life Laboratory, Uppsala University 75124 Uppsala Sweden
| | - Weifeng Lin
- Department of Chemistry - BMC, Science for Life Laboratory, Uppsala University 75124 Uppsala Sweden
| | - Vladyslav Dovhalyuk
- Department of Chemistry - BMC, Science for Life Laboratory, Uppsala University 75124 Uppsala Sweden
| | - Léna Driutti
- Department of Chemistry - BMC, Science for Life Laboratory, Uppsala University 75124 Uppsala Sweden
| | - Maria Letizia Di Martino
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University 75123 Uppsala Sweden
| | - Miroslav Vujasinovic
- Department for Digestive Diseases, Karolinska University Hospital Stockholm Sweden
| | - J-Matthias Löhr
- Department for Digestive Diseases, Karolinska University Hospital Stockholm Sweden
- Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institute Stockholm Sweden
| | - Mikael E Sellin
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University 75123 Uppsala Sweden
| | - Daniel Globisch
- Department of Chemistry - BMC, Science for Life Laboratory, Uppsala University 75124 Uppsala Sweden
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10
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Grüttner J, van Rijn JM, Geiser P, Florbrant A, Webb DL, Hellström PM, Sundbom M, Sellin ME, Svärd SG. Trophozoite fitness dictates the intestinal epithelial cell response to Giardia intestinalis infection. PLoS Pathog 2023; 19:e1011372. [PMID: 37141303 DOI: 10.1371/journal.ppat.1011372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/16/2023] [Accepted: 04/18/2023] [Indexed: 05/06/2023] Open
Abstract
Giardia intestinalis is a non-invasive, protozoan parasite infecting the upper small intestine of most mammals. Symptomatic infections cause the diarrhoeal disease giardiasis in humans and animals, but at least half of the infections are asymptomatic. However, the molecular underpinnings of these different outcomes of the infection are still poorly defined. Here, we studied the early transcriptional response to G. intestinalis trophozoites, the disease-causing life-cycle stage, in human enteroid-derived, 2-dimensional intestinal epithelial cell (IEC) monolayers. Trophozoites preconditioned in media that maximise parasite fitness triggered only neglectable inflammatory transcription in the IECs during the first hours of co-incubation. By sharp contrast, "non-fit" or lysed trophozoites induced a vigorous IEC transcriptional response, including high up-regulation of many inflammatory cytokines and chemokines. Furthermore, "fit" trophozoites could even suppress the stimulatory effect of lysed trophozoites in mixed infections, suggesting active G. intestinalis suppression of the IEC response. By dual-species RNA-sequencing, we defined the IEC and G. intestinalis gene expression programs associated with these differential outcomes of the infection. Taken together, our results inform on how G. intestinalis infection can lead to such highly variable effects on the host, and pinpoints trophozoite fitness as a key determinant of the IEC response to this common parasite.
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Affiliation(s)
- Jana Grüttner
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Jorik M van Rijn
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Petra Geiser
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Alexandra Florbrant
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Dominic-Luc Webb
- Department of Medical Sciences, Gastroenterology and Hepatology Unit, Uppsala University, Uppsala, Sweden
| | - Per M Hellström
- Department of Medical Sciences, Gastroenterology and Hepatology Unit, Uppsala University, Uppsala, Sweden
| | - Magnus Sundbom
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Mikael E Sellin
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Staffan G Svärd
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
- Science for Life Laboratory, Uppsala University, Uppsala, Sweden
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11
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Hammar R, Sellin ME, Artursson P. Epithelial and microbial determinants of colonic drug distribution. Eur J Pharm Sci 2023; 183:106389. [PMID: 36690119 DOI: 10.1016/j.ejps.2023.106389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/18/2023] [Accepted: 01/19/2023] [Indexed: 01/21/2023]
Abstract
A dynamic epithelium and a rich microbiota, separated by multi-layered mucus, make up the complex colonic cellular environment. Both cellular systems are characterized by high inter- and intraindividual differences, but their impact on drug distribution and efficacy remains incompletely understood. This research gap is pressing, as, e.g., inflammatory disorders of the colon are on the rise globally. In an effort to help close this gap, we provide considerations on determining colonic epithelial and microbial cellular parameters, and their impact on drug bioavailability. First, we cover the major cell types found in vivo within the epithelium and microbiota, and discuss how they can be modeled in vitro. We then draw attention to their structural similarities and differences with regard to determinants of drug distribution. Once a drug is solubilized in the luminal fluids, there are two main classes of such determinants: 1) binding processes, and 2) transporters and drug-metabolizing enzymes. Binding lowers the unbound intracellular fraction (fu,cell), which will, in turn, limit the amount of drug available for transport to desired sites. Transporters and drug metabolizing enzymes are ADME proteins impacting intracellular accumulation (Kp). Across cell types, we point out which processes are likely particularly impactful. Together, fu,cell and Kp can be used to describe intracellular bioavailability (Fic), which is a measure of local drug distribution, with consequences for efficacy. Determining these cellular parameters will be beneficial in understanding colonic drug distribution and will advance the field of drug delivery.
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Affiliation(s)
- Rebekkah Hammar
- Department of Pharmacy, Uppsala University, Husargatan 3, 751 23 Uppsala, Sweden
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Husargatan 3, 751 23 Uppsala, Sweden
| | - Per Artursson
- Department of Pharmacy, Uppsala University, Husargatan 3, 751 23 Uppsala, Sweden.
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12
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Tzavlaki K, Ohata Y, Morén A, Watanabe Y, Eriksson J, Tsuchiya M, Kubo Y, Yamamoto K, Sellin ME, Kato M, Caja L, Heldin CH, Moustakas A. The liver kinase B1 supports mammary epithelial morphogenesis by inhibiting critical factors that mediate epithelial-mesenchymal transition. J Cell Physiol 2023; 238:790-812. [PMID: 36791282 DOI: 10.1002/jcp.30975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 01/24/2023] [Accepted: 01/31/2023] [Indexed: 02/17/2023]
Abstract
The liver kinase B1 (LKB1) controls cellular metabolism and cell polarity across species. We previously established a mechanism for negative regulation of transforming growth factor β (TGFβ) signaling by LKB1. The impact of this mechanism in the context of epithelial polarity and morphogenesis remains unknown. After demonstrating that human mammary tissue expresses robust LKB1 protein levels, whereas invasive breast cancer exhibits significantly reduced LKB1 levels, we focused on mammary morphogenesis studies in three dimensional (3D) acinar organoids. CRISPR/Cas9-introduced loss-of-function mutations of STK11 (LKB1) led to profound defects in the formation of 3D organoids, resulting in amorphous outgrowth and loss of rotation of young organoids embedded in matrigel. This defect was associated with an enhanced signaling by TGFβ, including TGFβ auto-induction and induction of transcription factors that mediate epithelial-mesenchymal transition (EMT). Protein marker analysis confirmed a more efficient EMT response to TGFβ signaling in LKB1 knockout cells. Accordingly, chemical inhibition of the TGFβ type I receptor kinase largely restored the morphogenetic defect of LKB1 knockout cells. Similarly, chemical inhibition of the bone morphogenetic protein pathway or the TANK-binding kinase 1, or genetic silencing of the EMT factor SNAI1, partially restored the LKB1 knockout defect. Thus, LKB1 sustains mammary epithelial morphogenesis by limiting pathways that promote EMT. The observed downregulation of LKB1 expression in breast cancer is therefore predicted to associate with enhanced EMT induced by SNAI1 and TGFβ family members.
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Affiliation(s)
- Kalliopi Tzavlaki
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Yae Ohata
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Anita Morén
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Yukihide Watanabe
- Department of Experimental Pathology and Transborder Medical Research Center, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Jens Eriksson
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Maiko Tsuchiya
- Department of Oral Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.,Department of Pathology, Teikyo University School of Medicine, Tokyo, Japan
| | - Yuki Kubo
- Department of Comprehensive Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kouhei Yamamoto
- Department of Comprehensive Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Mitsuyasu Kato
- Department of Experimental Pathology and Transborder Medical Research Center, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Laia Caja
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Carl-Henrik Heldin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Aristidis Moustakas
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Biomedical Center, Uppsala University, Uppsala, Sweden
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13
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Geiser P, van Rijn JM, Sellin ME. Time-Lapse Imaging of Inflammasome-Dependent Cell Death and Extrusion in Enteroid-Derived Intestinal Epithelial Monolayers. Methods Mol Biol 2023; 2641:203-221. [PMID: 37074653 DOI: 10.1007/978-1-0716-3040-2_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
Inflammasome-induced cell death is an epithelium-intrinsic innate immune response to pathogenic onslaught on epithelial barriers, caused by invasive microbes such as Salmonella Typhimurium (S.Tm). Pattern recognition receptors detect pathogen- or damage-associated ligands and elicit inflammasome formation. This ultimately restricts bacterial loads within the epithelium, limits breaching of the barrier, and prevents detrimental inflammatory tissue damage. Pathogen restriction is mediated via the specific extrusion of dying intestinal epithelial cells (IECs) from the epithelial tissue, accompanied by membrane permeabilization at some stage of the process. These inflammasome-dependent mechanisms can be studied in real time in intestinal epithelial organoids (enteroids), which allow imaging at high temporal and spatial resolution in a stable focal plane when seeded as 2D monolayers. The protocols described here involve the establishment of murine and human enteroid-derived monolayers, as well as time-lapse imaging of IEC extrusion and membrane permeabilization following inflammasome activation by S.Tm infection. The protocols can be adapted to also study other pathogenic insults or combined with genetic and pharmacological manipulation of the involved pathways.
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Affiliation(s)
- Petra Geiser
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Jorik M van Rijn
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- Current address: Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
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14
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Di Martino ML, Sellin ME. Barcoded Consortium Infections: A Scalable, Internally Controlled Method to Study Host Cell Binding and Invasion by Pathogenic Bacteria. Methods Mol Biol 2023; 2674:295-311. [PMID: 37258976 DOI: 10.1007/978-1-0716-3243-7_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Bacterial host cell invasion has routinely been investigated by gentamicin protection assays, which are laborsome and suffer from pronounced experimental noise. This chapter describes an internally controlled, medium- to high-throughput method that resolves the capacity of multiple Salmonella virulence factor mutant strains to bind and invade host cells. The method, widely applicable to also other pathogens, is based on the combination of consortia of genetically tagged isogenic bacterial strains and a modified gentamicin protection assay. These protocols provide a flexible tool box to stringently quantify host cell binding and invasive properties of different mutants. Moreover, the method can be applied to both infections of cultured host cells and in vivo animal models, providing a comparable genetic readout, which greatly facilitates comparisons across experimental models.
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Affiliation(s)
- Maria Letizia Di Martino
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
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15
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Skovajsová E, Colonna B, Prosseda G, Sellin ME, Di Martino ML. The VirF21:VirF30 protein ratio is affected by temperature and impacts Shigella flexneri host cell invasion. FEMS Microbiol Lett 2022; 369:fnac043. [PMID: 35521699 PMCID: PMC9217107 DOI: 10.1093/femsle/fnac043] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 05/21/2022] [Accepted: 05/04/2022] [Indexed: 11/23/2022] Open
Abstract
Shigella spp, the etiological agents of bacillary dysentery in humans, have evolved an intricate regulatory strategy to ensure fine-tuned expression of virulence genes in response to environmental stimuli. A key component in this regulation is VirF, an AraC-like transcription factor, which at the host temperature (37°C) triggers, directly or indirectly, the expression of > 30 virulence genes important for invasion of the intestinal epithelium. Previous work identified two different forms of VirF with distinct functions: VirF30 activates virulence gene expression, while VirF21 appears to negatively regulate virF itself. Moreover, VirF21 originates from either differential translation of the virF mRNA or from a shorter leaderless mRNA (llmRNA). Here we report that both expression of the virF21 llmRNA and the VirF21:VirF30 protein ratio are higher at 30°C than at 37°C, suggesting a possible involvement of VirF21 in minimizing virulence gene expression outside the host (30°C). Ectopic elevation of VirF21 levels at 37°C indeed suppresses Shigella´s ability to infect epithelial cells. Finally, we find that the VirF21 C-terminal portion, predicted to contain a Helix-Turn-Helix motif (HTH2), is required for the functionality of this negative virulence regulator.
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Affiliation(s)
- Eva Skovajsová
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, 75123, Sweden
| | - Bianca Colonna
- Department of Biology and Biotechnology “C. Darwin”, Istituto Pasteur Italia, Sapienza Università di Roma, Rome, 00185, Italy
| | - Gianni Prosseda
- Department of Biology and Biotechnology “C. Darwin”, Istituto Pasteur Italia, Sapienza Università di Roma, Rome, 00185, Italy
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, 75123, Sweden
| | - Maria Letizia Di Martino
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, 75123, Sweden
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16
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Tsubakihara Y, Ohata Y, Okita Y, Younis S, Eriksson J, Sellin ME, Ren J, Ten Dijke P, Miyazono K, Hikita A, Imamura T, Kato M, Heldin CH, Moustakas A. TGFβ selects for pro-stemness over pro-invasive phenotypes during cancer cell epithelial-mesenchymal transition. Mol Oncol 2022; 16:2330-2354. [PMID: 35348275 PMCID: PMC9208077 DOI: 10.1002/1878-0261.13215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 02/07/2022] [Accepted: 03/24/2022] [Indexed: 11/08/2022] Open
Abstract
Transforming growth factor β (TGFβ) induces epithelial-mesenchymal transition (EMT), which correlates with stemness and invasiveness. Mesenchymal-epithelial transition (MET) is induced by TGFβ withdrawal and correlates with metastatic colonization. Whether TGFβ promotes stemness and invasiveness simultaneously via EMT remains unclear. We established a breast cancer cell model expressing red fluorescent protein (RFP) under the E-cadherin promoter. In 2D cultures, TGFβ induced EMT, generating RFPlow cells with a mesenchymal transcriptome, and regained RFP, with an epithelial transcriptome, after MET induced by TGFβ withdrawal. RFPlow cells generated robust mammospheres, with epithelio-mesenchymal cell surface features. Mammospheres that were forced to adhere generated migratory cells, devoid of RFP, a phenotype which was inhibited by a TGFβ receptor kinase inhibitor. Further stimulation of RFPlow mammospheres with TGFβ suppressed the generation of motile cells, but enhanced mammosphere growth. Accordingly, mammary fat-pad-transplanted mammospheres, in the absence of exogenous TGFβ treatment, established lung metastases with evident MET (RFPhigh cells). In contrast, TGFβ-treated mammospheres revealed high tumor-initiating capacity, but limited metastatic potential. Thus, the biological context of partial EMT and MET allows TGFβ to differentiate between pro-stemness and pro-invasive phenotypes.
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Affiliation(s)
- Yutaro Tsubakihara
- Dept. of Medical Biochemistry and Microbiology, Science for Life Laboratory, Box 582, Biomedical Center, Uppsala University, SE-75123, Uppsala, Sweden.,Dept. of Experimental Pathology and Transborder Medical Research Center, Faculty of Medicine, University of Tsukuba, Japan
| | - Yae Ohata
- Dept. of Medical Biochemistry and Microbiology, Science for Life Laboratory, Box 582, Biomedical Center, Uppsala University, SE-75123, Uppsala, Sweden
| | - Yukari Okita
- Dept. of Experimental Pathology and Transborder Medical Research Center, Faculty of Medicine, University of Tsukuba, Japan
| | - Shady Younis
- Dept. of Medical Biochemistry and Microbiology, Science for Life Laboratory, Box 582, Biomedical Center, Uppsala University, SE-75123, Uppsala, Sweden.,Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA, 94305, USA
| | - Jens Eriksson
- Dept. of Medical Biochemistry and Microbiology, Science for Life Laboratory, Box 582, Biomedical Center, Uppsala University, SE-75123, Uppsala, Sweden
| | - Mikael E Sellin
- Dept. of Medical Biochemistry and Microbiology, Science for Life Laboratory, Box 582, Biomedical Center, Uppsala University, SE-75123, Uppsala, Sweden
| | - Jiang Ren
- Dept. of Cell and Chemical Biology, Oncode Institute, Leiden University Medical Center, Leiden, The Netherlands
| | - Peter Ten Dijke
- Dept. of Cell and Chemical Biology, Oncode Institute, Leiden University Medical Center, Leiden, The Netherlands
| | - Kohei Miyazono
- Dept. of Molecular Pathology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Atsuhiko Hikita
- Div. of Tissue Engineering, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Takeshi Imamura
- Dept. of Molecular Medicine for Pathogenesis, Graduate School of Medicine, Ehime University, Toon, Japan
| | - Mitsuyasu Kato
- Dept. of Experimental Pathology and Transborder Medical Research Center, Faculty of Medicine, University of Tsukuba, Japan
| | - Carl-Henrik Heldin
- Dept. of Medical Biochemistry and Microbiology, Science for Life Laboratory, Box 582, Biomedical Center, Uppsala University, SE-75123, Uppsala, Sweden
| | - Aristidis Moustakas
- Dept. of Medical Biochemistry and Microbiology, Science for Life Laboratory, Box 582, Biomedical Center, Uppsala University, SE-75123, Uppsala, Sweden
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17
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Ek V, Fattinger SA, Florbrant A, Hardt WD, Di Martino ML, Eriksson J, Sellin ME. A Motile Doublet Form of Salmonella Typhimurium Diversifies Target Search Behaviour at the Epithelial Surface. Mol Microbiol 2022; 117:1156-1172. [PMID: 35332598 PMCID: PMC9325389 DOI: 10.1111/mmi.14898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 02/24/2022] [Accepted: 03/21/2022] [Indexed: 12/01/2022]
Abstract
The behaviors of infectious bacteria are commonly studied in bulk. This is effective to define the general properties of a given isolate, but insufficient to resolve subpopulations and unique single‐microbe behaviors within the bacterial pool. We here employ microscopy to study single‐bacterium characteristics among Salmonella enterica serovar Typhimurium (S.Tm), as they prepare for and launch invasion of epithelial host cells. We find that during the bacterial growth cycle, S.Tm populations switch gradually from fast planktonic growth to a host cell‐invasive phenotype, characterized by flagellar motility and expression of the Type‐three‐secretion‐system‐1. The indistinct nature of this shift leads to the establishment of a transient subpopulation of S.Tm “doublets”—waist‐bearing bacteria anticipating cell division—which simultaneously express host cell invasion machinery. In epithelial cell culture infections, these S.Tm doublets outperform their “singlet” brethren and represent a hyperinvasive subpopulation. Atop both glass and enteroid‐derived monolayers, doublets swim along markedly straighter trajectories than singlets, thereby diversifying search patterns and improving the surface exploration capacity of the total bacterial population. The straighter swimming, combined with an enhanced cell‐adhesion propensity, suffices to account for the hyperinvasive doublet phenotype. This work highlights bacterial cell length heterogeneity as a key determinant of target search patterns atop epithelia.
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Affiliation(s)
- Viktor Ek
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden
| | - Stefan A Fattinger
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden.,Institute of Microbiology, Department of Biology, ETH, Zurich, Zurich, Switzerland
| | - Alexandra Florbrant
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH, Zurich, Zurich, Switzerland
| | - Maria Letizia Di Martino
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden
| | - Jens Eriksson
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden
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18
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Méndez-Enríquez E, Salomonsson M, Eriksson J, Janson C, Malinovschi A, Sellin ME, Hallgren J. IgE cross-linking induces activation of human and mouse mast cell progenitors. J Allergy Clin Immunol 2021; 149:1458-1463. [PMID: 34492259 DOI: 10.1016/j.jaci.2021.08.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 06/28/2021] [Accepted: 08/30/2021] [Indexed: 12/16/2022]
Abstract
BACKGROUND The concept of innate and adaptive effector cells that are repleted by maturing inert progenitor cell populations is changing. Mast cells develop from rare mast cell progenitors populating peripheral tissues at homeostatic conditions, or as a result of induced recruitment during inflammatory conditions. OBJECTIVE Because FcεRI-expressing mast cell progenitors are the dominating mast cell type during acute allergic lung inflammation in vivo, we hypothesized that they are activated by IgE cross-linking. METHODS Mouse peritoneal and human peripheral blood cells were sensitized and stimulated with antigen, or stimulated with anti-IgE, and the mast cell progenitor population analyzed for signs of activation by flow cytometry. Isolated peritoneal mast cell progenitors were studied before and after anti-IgE stimulation at single-cell level by time-lapse fluorescence microscopy. Lung mast cell progenitors were analyzed for their ability to produce IL-13 by intracellular flow cytometry in a mouse model of ovalbumin-induced allergic airway inflammation. RESULTS Sensitized mouse peritoneal mast cell progenitors demonstrate increased levels of phosphorylation of tyrosines on intracellular proteins (total tyrosine phosphorylation), and spleen tyrosine kinase (Syk) phosphorylation after antigen exposure. Anti-IgE induced cell surface-associated lysomal-associated membrane protein-1 (LAMP-1) in naive mast cell progenitors, and prompted loss of fluorescence signal and altered morphology of isolated cells loaded with lysotracker. In human mast cell progenitors, anti-IgE increased total tyrosine phosphorylation, cell surface-associated LAMP-1, and CD63. Lung mast cell progenitors from mice with ovalbumin-induced allergic airway inflammation produce IL-13. CONCLUSIONS Mast cell progenitors become activated by IgE cross-linking and may contribute to the pathology associated with acute allergic airway inflammation.
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Affiliation(s)
- Erika Méndez-Enríquez
- Department of Medical Biochemistry and Microbiology, BMC, Uppsala University, Uppsala, Sweden
| | - Maya Salomonsson
- Department of Medical Biochemistry and Microbiology, BMC, Uppsala University, Uppsala, Sweden
| | - Jens Eriksson
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Christer Janson
- Department of Medical Sciences: Respiratory, Allergy and Sleep Research, Uppsala University, Uppsala, Sweden
| | - Andrei Malinovschi
- Department of Medical Sciences: Clinical Physiology, Uppsala University, Uppsala, Sweden
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Jenny Hallgren
- Department of Medical Biochemistry and Microbiology, BMC, Uppsala University, Uppsala, Sweden.
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19
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Fattinger SA, Sellin ME, Hardt WD. Salmonella effector driven invasion of the gut epithelium: breaking in and setting the house on fire. Curr Opin Microbiol 2021; 64:9-18. [PMID: 34492596 DOI: 10.1016/j.mib.2021.08.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 08/10/2021] [Accepted: 08/17/2021] [Indexed: 12/15/2022]
Abstract
Salmonella Typhimurium (S.Tm) is a major cause of diarrheal disease. The invasion into intestinal epithelial cells (IECs) is a central step in the infection cycle. It is associated with gut inflammation and thought to benefit S.Tm proliferation also in the intestinal lumen. Importantly, it is still not entirely clear how inflammation is elicited and to which extent it links to IEC invasion efficiency in vivo. In this review, we summarize recent findings explaining IEC invasion by type-three-secretion-system-1 (TTSS-1) effector proteins and discuss their effects on invasion and gut inflammation. In non-polarized tissue culture cells, the TTSS-1 effectors (mainly SopB/E/E2) elicit large membrane ruffles fueling cooperative invasion, and can directly trigger pro-inflammatory signaling. By contrast, in the murine gut, we observe discreet-invasion (mainly via the TTSS-1 effector SipA) and a prominent pro-inflammatory role of the host?"s epithelial inflammasome(s), which sense pathogen associated molecular patterns (PAMPs). We discuss why it has remained a major challenge to tease apart direct and indirect inflammatory effects of TTSS-1 effectors and explain why further research will be needed to fully determine their inflammation-modulating role(s).
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Affiliation(s)
- Stefan A Fattinger
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland; Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland.
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20
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Fattinger SA, Sellin ME, Hardt WD. Epithelial inflammasomes in the defense against Salmonella gut infection. Curr Opin Microbiol 2020; 59:86-94. [PMID: 33128958 DOI: 10.1016/j.mib.2020.09.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/15/2020] [Accepted: 09/22/2020] [Indexed: 02/06/2023]
Abstract
The gut epithelium prevents bacterial access to the host's tissues and coordinates a number of mucosal defenses. Here, we review the function of epithelial inflammasomes in the infected host and focus on their role in defense against Salmonella Typhimurium. This pathogen employs flagella to swim towards the epithelium and a type III secretion system (TTSS) to dock and invade intestinal epithelial cells. Flagella and TTSS components are recognized by the canonical NAIP/NLRC4 inflammasome, while LPS activates the non-canonical Caspase-4/11 inflammasome. The relative contributions of these inflammasomes, the activated cell death pathways and the elicited mucosal defenses are subject to environmental control and appear to change along the infection trajectory. It will be an important future task to explain how this may enable defense against the challenges imposed by diverse bacterial enteropathogens.
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Affiliation(s)
- Stefan A Fattinger
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland; Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland.
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21
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Furter M, Sellin ME, Hansson GC, Hardt WD. Mucus Architecture and Near-Surface Swimming Affect Distinct Salmonella Typhimurium Infection Patterns along the Murine Intestinal Tract. Cell Rep 2020; 27:2665-2678.e3. [PMID: 31141690 PMCID: PMC6547020 DOI: 10.1016/j.celrep.2019.04.106] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 04/01/2019] [Accepted: 04/24/2019] [Indexed: 12/22/2022] Open
Abstract
Mucus separates gut-luminal microbes from the tissue. It is unclear how pathogens like Salmonella Typhimurium (S.Tm) can overcome this obstacle. Using live microscopy, we monitored S.Tm interactions with native murine gut explants and studied how mucus affects the infection. A dense inner mucus layer covers the distal colon tissue, limiting direct tissue access. S.Tm performs near-surface swimming on this mucus layer, which allows probing for colon mucus heterogeneities, but can also entrap the bacterium in the dense inner colon mucus layer. In the cecum, dense mucus fills only the bottom of the intestinal crypts, leaving the epithelium between crypts unshielded and prone to access by motile and non-motile bacteria alike. This explains why the cecum is highly infection permissive and represents the primary site of S.Tm enterocolitis in the streptomycin mouse model. Our findings highlight the importance of mucus in intestinal defense and homeostasis. Live imaging of Salmonella near-surface swimming on mouse colon inner mucus layer Colon inner mucus layer traversal requires mucus breaches and flagellar propulsion The mouse cecum lacks a continuous mucus layer, leaving epithelium tips uncovered Exposed cecum epithelium tips are a hotspot for Salmonella infection
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Affiliation(s)
- Markus Furter
- Institute for Microbiology, ETH Zürich, 8093 Zürich, Switzerland
| | - Mikael E Sellin
- Institute for Microbiology, ETH Zürich, 8093 Zürich, Switzerland
| | - Gunnar C Hansson
- Department of Medical Biochemistry, University of Gothenburg, 40530 Gothenburg, Sweden
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22
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Hausmann A, Russo G, Grossmann J, Zünd M, Schwank G, Aebersold R, Liu Y, Sellin ME, Hardt W. Germ-free and microbiota-associated mice yield small intestinal epithelial organoids with equivalent and robust transcriptome/proteome expression phenotypes. Cell Microbiol 2020; 22:e13191. [PMID: 32068945 PMCID: PMC7317401 DOI: 10.1111/cmi.13191] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/09/2020] [Accepted: 01/13/2020] [Indexed: 12/12/2022]
Abstract
Intestinal epithelial organoids established from gut tissue have become a widely used research tool. However, it remains unclear how environmental cues, divergent microbiota composition and other sources of variation before, during and after establishment confound organoid properties, and how these properties relate to the original tissue. While environmental influences cannot be easily addressed in human organoids, mice offer a controlled assay-system. Here, we probed the effect of donor microbiota differences, previously identified as a confounding factor in murine in vivo studies, on organoids. We analysed the proteomes and transcriptomes of primary organoid cultures established from two colonised and one germ-free mouse colony of C57BL/6J genetic background, and compared them to their tissue of origin and commonly used cell lines. While an imprint of microbiota-exposure was observed on the proteome of epithelial samples, the long-term global impact of donor microbiota on organoid expression patterns was negligible. Instead, stochastic culture-to-culture differences accounted for a moderate variability between independently established organoids. Integration of transcriptome and proteome datasets revealed an organoid-typic expression signature comprising 14 transcripts and 10 proteins that distinguished organoids across all donors from murine epithelial cell lines and fibroblasts and closely mimicked expression patterns in the gut epithelium. This included the inflammasome components ASC, Naip1-6, Nlrc4 and Caspase-1, which were highly expressed in all organoids compared to the reference cell line m-ICc12 or mouse embryonic fibroblasts. Taken together, these results reveal that the donor microbiota has little effect on the organoid phenotype and suggest that organoids represent a more suitable culture model than immortalised cell lines, in particular for studies of intestinal epithelial inflammasomes.
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Affiliation(s)
- Annika Hausmann
- Institute of Microbiology, Department of BiologyETH ZurichZurichSwitzerland
| | - Giancarlo Russo
- Functional Genomics Center ZurichUniversity of ZurichZurichSwitzerland
| | - Jonas Grossmann
- Functional Genomics Center ZurichUniversity of ZurichZurichSwitzerland
| | - Mirjam Zünd
- Institute of Microbiology, Department of BiologyETH ZurichZurichSwitzerland
| | - Gerald Schwank
- Institute of Pharmacology and ToxicologyUniversity of ZurichZurichSwitzerland
| | - Ruedi Aebersold
- Institute of Systems Biology, Department of BiologyETH ZurichZurichSwitzerland
| | - Yansheng Liu
- Institute of Systems Biology, Department of BiologyETH ZurichZurichSwitzerland
- Department of Pharmacology, Cancer Biology InstituteYale University School of MedicineWest HavenConnecticutUSA
| | - Mikael E. Sellin
- Institute of Microbiology, Department of BiologyETH ZurichZurichSwitzerland
- Science for Life Laboratory, Department of Medical Biochemistry and MicrobiologyUppsala UniversityUppsalaSweden
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23
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Fattinger SA, Böck D, Di Martino ML, Deuring S, Samperio Ventayol P, Ek V, Furter M, Kreibich S, Bosia F, Müller-Hauser AA, Nguyen BD, Rohde M, Pilhofer M, Hardt WD, Sellin ME. Salmonella Typhimurium discreet-invasion of the murine gut absorptive epithelium. PLoS Pathog 2020; 16:e1008503. [PMID: 32365138 PMCID: PMC7224572 DOI: 10.1371/journal.ppat.1008503] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 05/14/2020] [Accepted: 03/26/2020] [Indexed: 01/15/2023] Open
Abstract
Salmonella enterica serovar Typhimurium (S.Tm) infections of cultured cell lines have given rise to the ruffle model for epithelial cell invasion. According to this model, the Type-Three-Secretion-System-1 (TTSS-1) effectors SopB, SopE and SopE2 drive an explosive actin nucleation cascade, resulting in large lamellipodia- and filopodia-containing ruffles and cooperative S.Tm uptake. However, cell line experiments poorly recapitulate many of the cell and tissue features encountered in the host’s gut mucosa. Here, we employed bacterial genetics and multiple imaging modalities to compare S.Tm invasion of cultured epithelial cell lines and the gut absorptive epithelium in vivo in mice. In contrast to the prevailing ruffle-model, we find that absorptive epithelial cell entry in the mouse gut occurs through “discreet-invasion”. This distinct entry mode requires the conserved TTSS-1 effector SipA, involves modest elongation of local microvilli in the absence of expansive ruffles, and does not favor cooperative invasion. Discreet-invasion preferentially targets apicolateral hot spots at cell–cell junctions and shows strong dependence on local cell neighborhood. This proof-of-principle evidence challenges the current model for how S.Tm can enter gut absorptive epithelial cells in their intact in vivo context. Bacterial pathogens can use secreted effector molecules to drive entry into host cells. Studies of the intestinal pathogen S.Tm have been central to uncover the mechanistic basis for the entry process. More than two decades of research have resulted in a detailed model for how S.Tm invades gut epithelial cells through effector triggering of large Rho-GTPase-dependent actin ruffles. However, the evidence for this model comes predominantly from studies in cultured cell lines. These experimental systems lack many of the architectural and signaling features of the intact gut epithelium. Our study surprisingly reveals that in the intact mouse gut, S.Tm invades absorptive epithelial cells through a process that does not require the Rho-GTPase-activating effectors and can proceed in the absence of the prototypical ruffling response. Instead, S.Tm exploits another effector, SipA, to sneak in through discreet entry structures close to cell–cell junctions. Our results challenge the current model for S.Tm epithelial cell entry and emphasizes the need of taking a physiological host cell context into account when studying bacterium–host cell interactions.
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Affiliation(s)
- Stefan A. Fattinger
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Desirée Böck
- Institute of Molecular Biology & Biophysics, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Maria Letizia Di Martino
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Sabrina Deuring
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Pilar Samperio Ventayol
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Viktor Ek
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Markus Furter
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Saskia Kreibich
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Francesco Bosia
- Institute of Molecular Biology & Biophysics, Department of Biology, ETH Zürich, Zürich, Switzerland
| | | | - Bidong D. Nguyen
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Manfred Rohde
- Central Facility for Microscopy, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Martin Pilhofer
- Institute of Molecular Biology & Biophysics, Department of Biology, ETH Zürich, Zürich, Switzerland
- * E-mail: (MP); (WDH); (MES)
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
- * E-mail: (MP); (WDH); (MES)
| | - Mikael E. Sellin
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- * E-mail: (MP); (WDH); (MES)
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24
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Bakkeren E, Huisman JS, Fattinger SA, Hausmann A, Furter M, Egli A, Slack E, Sellin ME, Bonhoeffer S, Regoes RR, Diard M, Hardt WD. Salmonella persisters promote the spread of antibiotic resistance plasmids in the gut. Nature 2019; 573:276-280. [PMID: 31485077 PMCID: PMC6744281 DOI: 10.1038/s41586-019-1521-8] [Citation(s) in RCA: 135] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 08/05/2019] [Indexed: 12/17/2022]
Abstract
The emergence of antibiotic resistant bacteria by mutations or by acquisition of genetic material like resistance plasmids represents a major public health issue 1,2 (Extended Data Fig. 1a). Persisters are bacterial subpopulations surviving antibiotics by reversibly adapting their physiology 3–10. They promote the emergence of antibiotic resistant mutants 11. We asked if persisters can also promote the spread of resistance plasmids. In contrast to mutations, resistance plasmid transfer requires the co-occurrence of two different bacterial strains: a donor and a recipient (Extended Data Fig. 1a). For our experiments, we chose the facultative intracellular entero-pathogen Salmonella enterica serovar Typhimurium (S.Tm) and E. coli, a common microbiota member 12. S.Tm forms persisters surviving antibiotic therapy in several host tissues. We show that tissue-associated, S.Tm persisters account for long-lived reservoirs of plasmid donors or recipients. Persistent S.Tm reservoir formation requires Salmonella Pathogenicity Island (SPI) -1/2 in the gut-associated tissues or SPI-2 at systemic sites. Re-seeding of these bacteria into the gut lumen allows co-occurrence of donors with gut-resident recipients, thereby favouring plasmid transfer between various Enterobacteriaceae. We observe up to 99% transconjugants within 2-3 days after re-seeding. Mathematical modeling shows that rare re-seeding events may suffice for a high frequency of conjugation. Vaccination reduces tolerant reservoir formation after oral Salmonella infection and subsequent plasmid transfer. We conclude that even without selection for plasmid-encoded resistance genes, small persistent pathogen reservoirs can foster the spread of promiscuous resistance plasmids in the gut.
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Affiliation(s)
- Erik Bakkeren
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Jana S Huisman
- Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Stefan A Fattinger
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland.,Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Annika Hausmann
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Markus Furter
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Adrian Egli
- Division of Clinical Microbiology, University Hospital Basel, Basel, Switzerland.,Applied Microbiology Research, Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Emma Slack
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland.,Institute of Food, Nutrition and Health, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Sebastian Bonhoeffer
- Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
| | - Roland R Regoes
- Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
| | - Médéric Diard
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland. .,Biozentrum, University of Basel, Basel, Switzerland.
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland.
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25
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von Beek C, Waern I, Eriksson J, Melo FR, Robinson C, Waller AS, Sellin ME, Guss B, Pejler G. Streptococcal sagA activates a proinflammatory response in mast cells by a sublytic mechanism. Cell Microbiol 2019; 21:e13064. [PMID: 31155820 PMCID: PMC6771685 DOI: 10.1111/cmi.13064] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 05/10/2019] [Accepted: 05/26/2019] [Indexed: 01/21/2023]
Abstract
Mast cells are implicated in the innate proinflammatory immune defence against bacterial insult, but the mechanisms through which mast cells respond to bacterial encounter are poorly defined. Here, we addressed this issue and show that mast cells respond vividly to wild type Streptococcus equi by up‐regulating a panel of proinflammatory genes and by secreting proinflammatory cytokines. However, this response was completely abrogated when the bacteria lacked expression of sagA, whereas the lack of a range of other potential virulence genes (seeH, seeI, seeL, seeM, hasA, seM, aroB, pyrC, and recA) had no effect on the amplitude of the mast cell responses. The sagA gene encodes streptolysin S, a lytic toxin, and we next showed that the wild type strain but not a sagA‐deficient mutant induced lysis of mast cells. To investigate whether host cell membrane perturbation per se could play a role in the activation of the proinflammatory response, we evaluated the effects of detergent‐ and pneumolysin‐dependent lysis on mast cells. Indeed, exposure of mast cells to sublytic concentrations of all these agents resulted in cytokine responses of similar amplitudes as those caused by wild type streptococci. This suggests that sublytic membrane perturbation is sufficient to trigger full‐blown proinflammatory signalling in mast cells. Subsequent analysis showed that the p38 and Erk1/2 signalling pathways had central roles in the proinflammatory response of mast cells challenged by either sagA‐expressing streptococci or detergent. Altogether, these findings suggest that sagA‐dependent mast cell membrane perturbation is a mechanism capable of activating the innate immune response upon bacterial challenge.
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Affiliation(s)
- Christopher von Beek
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Ida Waern
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jens Eriksson
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Fabio Rabelo Melo
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Carl Robinson
- Department of Bacteriology, Animal Health Trust, Newmarket, UK
| | - Andrew S Waller
- Department of Bacteriology, Animal Health Trust, Newmarket, UK
| | - Mikael E Sellin
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Bengt Guss
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Gunnar Pejler
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.,Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
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26
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Herp S, Brugiroux S, Garzetti D, Ring D, Jochum LM, Beutler M, Eberl C, Hussain S, Walter S, Gerlach RG, Ruscheweyh HJ, Huson D, Sellin ME, Slack E, Hanson B, Loy A, Baines JF, Rausch P, Basic M, Bleich A, Berry D, Stecher B. Mucispirillum schaedleri Antagonizes Salmonella Virulence to Protect Mice against Colitis. Cell Host Microbe 2019; 25:681-694.e8. [DOI: 10.1016/j.chom.2019.03.004] [Citation(s) in RCA: 132] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/10/2019] [Accepted: 03/05/2019] [Indexed: 12/30/2022]
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27
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Diard M, Bakkeren E, Cornuault JK, Moor K, Hausmann A, Sellin ME, Loverdo C, Aertsen A, Ackermann M, De Paepe M, Slack E, Hardt WD. Inflammation boosts bacteriophage transfer between Salmonella spp. Science 2017; 355:1211-1215. [PMID: 28302859 DOI: 10.1126/science.aaf8451] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 12/19/2016] [Accepted: 02/22/2017] [Indexed: 12/12/2022]
Abstract
Bacteriophage transfer (lysogenic conversion) promotes bacterial virulence evolution. There is limited understanding of the factors that determine lysogenic conversion dynamics within infected hosts. A murine Salmonella Typhimurium (STm) diarrhea model was used to study the transfer of SopEΦ, a prophage from STm SL1344, to STm ATCC14028S. Gut inflammation and enteric disease triggered >55% lysogenic conversion of ATCC14028S within 3 days. Without inflammation, SopEΦ transfer was reduced by up to 105-fold. This was because inflammation (e.g., reactive oxygen species, reactive nitrogen species, hypochlorite) triggers the bacterial SOS response, boosts expression of the phage antirepressor Tum, and thereby promotes free phage production and subsequent transfer. Mucosal vaccination prevented a dense intestinal STm population from inducing inflammation and consequently abolished SopEΦ transfer. Vaccination may be a general strategy for blocking pathogen evolution that requires disease-driven transfer of temperate bacteriophages.
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Affiliation(s)
| | | | - Jeffrey K Cornuault
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy en Josas, France
| | - Kathrin Moor
- Institute of Microbiology, ETH Zurich, Switzerland
| | | | - Mikael E Sellin
- Institute of Microbiology, ETH Zurich, Switzerland.,Present address: Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden
| | - Claude Loverdo
- Laboratoire Jean Perrin (UMR 8237), CNRS-UPMC, 75005 Paris, France
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, KU Leuven, Belgium
| | - Martin Ackermann
- Department of Environmental Systems Science, ETH Zurich, and Department of Environmental Microbiology, Eawag, Switzerland
| | - Marianne De Paepe
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy en Josas, France
| | - Emma Slack
- Institute of Microbiology, ETH Zurich, Switzerland
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28
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Müller AA, Dolowschiak T, Sellin ME, Felmy B, Verbree C, Gadient S, Westermann AJ, Vogel J, LeibundGut-Landmann S, Hardt WD. An NK Cell Perforin Response Elicited via IL-18 Controls Mucosal Inflammation Kinetics during Salmonella Gut Infection. PLoS Pathog 2016; 12:e1005723. [PMID: 27341123 PMCID: PMC4920399 DOI: 10.1371/journal.ppat.1005723] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 06/03/2016] [Indexed: 01/26/2023] Open
Abstract
Salmonella Typhimurium (S.Tm) is a common cause of self-limiting diarrhea. The mucosal inflammation is thought to arise from a standoff between the pathogen's virulence factors and the host's mucosal innate immune defenses, particularly the mucosal NAIP/NLRC4 inflammasome. However, it had remained unclear how this switches the gut from homeostasis to inflammation. This was studied using the streptomycin mouse model. S.Tm infections in knockout mice, cytokine inhibition and –injection experiments revealed that caspase-1 (not -11) dependent IL-18 is pivotal for inducing acute inflammation. IL-18 boosted NK cell chemoattractants and enhanced the NK cells' migratory capacity, thus promoting mucosal accumulation of mature, activated NK cells. NK cell depletion and Prf-/- ablation (but not granulocyte-depletion or T-cell deficiency) delayed tissue inflammation. Our data suggest an NK cell perforin response as one limiting factor in mounting gut mucosal inflammation. Thus, IL-18-elicited NK cell perforin responses seem to be critical for coordinating mucosal inflammation during early infection, when S.Tm strongly relies on virulence factors detectable by the inflammasome. This may have broad relevance for mucosal defense against microbial pathogens. Salmonella Typhimurium is a common cause of foodborne diarrhea. The disease symptoms arise already a few hours after infection. However, it had remained unclear how the immune system can mount the responses eliciting the disease symptoms so quickly. Earlier work in a mouse model had shown that the gut epithelium expresses a sensor, called NAIP/NLRC4/caspase-1 inflammasome that can detect the pathogen and mount a defense by 12-18h p.i. However, it has remained uncharacterized how inflammasome sensing drives the initial gut inflammation. Here, we found that the caspase-1 inflammasome triggers the production of IL-18, a pro-inflammatory cytokine that appears essential for the early onset of inflammation. IL-18 is driving the accumulation of NK cells into the infected mucosa, via the upregulation of NK cell chemoattractants and by the stimulation of their migratory capacity. Mature NK cells seem to induce mucosal inflammation via a perforin-mediated cytotoxic response. These data suggest that the inflammasome/IL-18/NK cell axis is a driver of early mucosal inflammation via a perforin-dependent cytotoxic NK cell response. Future work will have to address, if this mechanism is equally potent in the human gut and may contribute to ramping up the host's response during the first hours of infection. This may have implications for other gut infections and might provide leads for developing therapies.
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Affiliation(s)
- Anna A. Müller
- Institute of Microbiology, ETH Zürich, Zürich, Switzerland
| | | | - Mikael E. Sellin
- Institute of Microbiology, ETH Zürich, Zürich, Switzerland
- Department of Cell and Molecular Biology, Microbiology, Uppsala University, Uppsala, Sweden
| | - Boas Felmy
- Institute of Microbiology, ETH Zürich, Zürich, Switzerland
| | | | - Sandra Gadient
- Institute of Microbiology, ETH Zürich, Zürich, Switzerland
| | | | - Jörg Vogel
- Institute for Molecular Infection Biology, University of Würzburg, Würzburg, Germany
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29
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Maier L, Diard M, Sellin ME, Chouffane ES, Trautwein-Weidner K, Periaswamy B, Slack E, Dolowschiak T, Stecher B, Loverdo C, Regoes RR, Hardt WD. Correction: Granulocytes Impose a Tight Bottleneck upon the Gut Luminal Pathogen Population during Salmonella Typhimurium Colitis. PLoS Pathog 2015; 11:e1005047. [PMID: 26186334 PMCID: PMC4506069 DOI: 10.1371/journal.ppat.1005047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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30
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Sellin ME, Maslowski KM, Maloy KJ, Hardt WD. Inflammasomes of the intestinal epithelium. Trends Immunol 2015; 36:442-50. [PMID: 26166583 DOI: 10.1016/j.it.2015.06.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 06/16/2015] [Accepted: 06/16/2015] [Indexed: 02/08/2023]
Abstract
While the functional importance of inflammasomes in blood-derived cell types is well established, it remains poorly understood how inflammasomes in nonhematopoietic cells contribute to mucosal immunity. Recent studies have revealed functional roles of inflammasomes - particularly NAIP/NLRC4, NLRP6, and noncanonical caspase-4 (caspase-11) - within epithelial cells of the gut in mucosal immune defense, inflammation, and tumorigenesis. Here, we review and discuss these findings in the broader context of tissue compartment-specific mucosal immunity. We propose several models whereby activities of the intestinal epithelial inflammasomes converge on mechanisms to remove compromised epithelial cells, maintain host-microbiota mutualism, and communicate with immune cells of the underlying lamina propria.
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Affiliation(s)
- Mikael E Sellin
- Institute of Microbiology, ETH Zürich, 8093 Zürich, Switzerland.
| | - Kendle M Maslowski
- Laboratory for Intestinal Ecosystem, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan
| | - Kevin J Maloy
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
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31
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Sellin ME, Müller AA, Felmy B, Dolowschiak T, Diard M, Tardivel A, Maslowski KM, Hardt WD. Epithelium-intrinsic NAIP/NLRC4 inflammasome drives infected enterocyte expulsion to restrict Salmonella replication in the intestinal mucosa. Cell Host Microbe 2015; 16:237-248. [PMID: 25121751 DOI: 10.1016/j.chom.2014.07.001] [Citation(s) in RCA: 279] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 05/20/2014] [Accepted: 06/30/2014] [Indexed: 01/08/2023]
Abstract
The gut mucosal epithelium separates the host from the microbiota, but enteropathogens such as Salmonella Typhimurium (S.Tm) can invade and breach this barrier. Defenses against such acute insults remain incompletely understood. Using a murine model of Salmonella enterocolitis, we analyzed mechanisms limiting pathogen loads in the epithelium during early infection. Although the epithelium-invading S.Tm replicate initially, this intraepithelial replicative niche is restricted by expulsion of infected enterocytes into the lumen. This mechanism is compromised if inflammasome components (NAIP1-6, NLRC4, caspase-1/-11) are deleted, or ablated specifically in the epithelium, resulting in ∼100-fold higher intraepithelial loads and accelerated lymph node colonization. Interestingly, the cytokines downstream of inflammasome activation, interleukin (IL)-1α/β and IL-18, appear dispensable for epithelial restriction of early infection. These data establish the role of an epithelium-intrinsic inflammasome, which drives expulsion of infected cells to restrict the pathogen's intraepithelial proliferation. This may represent a general defense mechanism against mucosal infections.
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Affiliation(s)
- Mikael E Sellin
- Institute of Microbiology, ETH Zürich, 8093 Zürich, Switzerland.
| | - Anna A Müller
- Institute of Microbiology, ETH Zürich, 8093 Zürich, Switzerland
| | - Boas Felmy
- Institute of Microbiology, ETH Zürich, 8093 Zürich, Switzerland
| | | | - Médéric Diard
- Institute of Microbiology, ETH Zürich, 8093 Zürich, Switzerland
| | - Aubry Tardivel
- Department of Biochemistry, University of Lausanne, 1066 Epalinges, Switzerland
| | - Kendle M Maslowski
- Department of Biochemistry, University of Lausanne, 1066 Epalinges, Switzerland; Laboratory for Intestinal Ecosystem, RIKEN Center for Integrative Medical Sciences (IMS), Yokohama 230-0045, Japan
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Maier L, Diard M, Sellin ME, Chouffane ES, Trautwein-Weidner K, Periaswamy B, Slack E, Dolowschiak T, Stecher B, Loverdo C, Regoes RR, Hardt WD. Granulocytes impose a tight bottleneck upon the gut luminal pathogen population during Salmonella typhimurium colitis. PLoS Pathog 2014; 10:e1004557. [PMID: 25522364 PMCID: PMC4270771 DOI: 10.1371/journal.ppat.1004557] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 11/06/2014] [Indexed: 12/22/2022] Open
Abstract
Topological, chemical and immunological barriers are thought to limit infection by enteropathogenic bacteria. However, in many cases these barriers and their consequences for the infection process remain incompletely understood. Here, we employed a mouse model for Salmonella colitis and a mixed inoculum approach to identify barriers limiting the gut luminal pathogen population. Mice were infected via the oral route with wild type S. Typhimurium (S. Tm) and/or mixtures of phenotypically identical but differentially tagged S. Tm strains ("WITS", wild-type isogenic tagged strains), which can be individually tracked by quantitative real-time PCR. WITS dilution experiments identified a substantial loss in tag/genetic diversity within the gut luminal S. Tm population by days 2-4 post infection. The diversity-loss was not attributable to overgrowth by S. Tm mutants, but required inflammation, Gr-1+ cells (mainly neutrophilic granulocytes) and most likely NADPH-oxidase-mediated defense, but not iNOS. Mathematical modelling indicated that inflammation inflicts a bottleneck transiently restricting the gut luminal S. Tm population to approximately 6000 cells and plating experiments verified a transient, inflammation- and Gr-1+ cell-dependent dip in the gut luminal S. Tm population at day 2 post infection. We conclude that granulocytes, an important clinical hallmark of S. Tm-induced inflammation, impose a drastic bottleneck upon the pathogen population. This extends the current view of inflammation-fuelled gut-luminal Salmonella growth by establishing the host response in the intestinal lumen as a double-edged sword, fostering and diminishing colonization in a dynamic equilibrium. Our work identifies a potent immune defense against gut infection and reveals a potential Achilles' heel of the infection process which might be targeted for therapy.
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Affiliation(s)
- Lisa Maier
- Eidgenössische Technische Hochschule Zürich, Institute of Microbiology, Zurich, Switzerland
| | - Médéric Diard
- Eidgenössische Technische Hochschule Zürich, Institute of Microbiology, Zurich, Switzerland
| | - Mikael E. Sellin
- Eidgenössische Technische Hochschule Zürich, Institute of Microbiology, Zurich, Switzerland
| | - Elsa-Sarah Chouffane
- Eidgenössische Technische Hochschule Zürich, Institute of Microbiology, Zurich, Switzerland
| | | | - Balamurugan Periaswamy
- Eidgenössische Technische Hochschule Zürich, Institute of Microbiology, Zurich, Switzerland
| | - Emma Slack
- Eidgenössische Technische Hochschule Zürich, Institute of Microbiology, Zurich, Switzerland
| | - Tamas Dolowschiak
- Eidgenössische Technische Hochschule Zürich, Institute of Microbiology, Zurich, Switzerland
| | - Bärbel Stecher
- Max von Pettenkofer-Institut, München, Germany; German Center for Infection Research (DZIF), partner site Ludwig Maximilian University of Munich, Munich, Germany
| | - Claude Loverdo
- Eidgenössische Technische Hochschule Zürich, Institute of Integrative Biology, Zurich, Switzerland
| | - Roland R. Regoes
- Eidgenössische Technische Hochschule Zürich, Institute of Integrative Biology, Zurich, Switzerland
| | - Wolf-Dietrich Hardt
- Eidgenössische Technische Hochschule Zürich, Institute of Microbiology, Zurich, Switzerland
- * E-mail:
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Vonaesch P, Sellin ME, Cardini S, Singh V, Barthel M, Hardt WD. The Salmonella Typhimurium effector protein SopE transiently localizes to the early SCV and contributes to intracellular replication. Cell Microbiol 2014; 16:1723-35. [PMID: 25052734 DOI: 10.1111/cmi.12333] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 06/19/2014] [Accepted: 07/05/2014] [Indexed: 12/28/2022]
Abstract
Salmonella enterica serovar Typhimurium (S. Tm) is a facultative intracellular pathogen that induces entry into non-phagocytic cells by a Type III secretion system (TTSS) and cognate effector proteins. Upon host cell entry, S. Tm expresses a second TTSS and subverts intracellular trafficking to create a replicative niche - the Salmonella-containing vacuole (SCV). SopE, a guanidyl exchange factor (GEF) for Rac1 and Cdc42, is translocated by the TTSS-1 upon host cell contact and promotes entry through triggering of actin-dependent ruffles. After host cell entry, the bulk of SopE undergoes proteasomal degradation. Here we show that a subfraction is however detectable on the nascent SCV membrane up to ∼ 6 h post infection. Membrane localization of SopE and the closely related SopE2 differentially depend on the Rho-GTPase-binding GEF domain, and to some extent involves also the unstructured N-terminus. SopE localizes transiently to the early SCV, dependent on continuous synthesis and secretion by the TTSS-1 during the intracellular state. Mutant strains lacking SopE or SopE2 are attenuated in early intracellular replication, while complementation restores this defect. Hence, the present study reveals an unanticipated role for SopE and SopE2 in establishing the Salmonella replicative niche, and further emphasizes the importance of entry effectors in later stages of host-cell manipulation.
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Affiliation(s)
- Pascale Vonaesch
- Institute of Microbiology, ETH Zürich, Vladimir-Prelog-Weg 4, 8093, Zürich, Switzerland
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Sellin ME, Stenmark S, Gullberg M. Cell type-specific expression of SEPT3-homology subgroup members controls the subunit number of heteromeric septin complexes. Mol Biol Cell 2014; 25:1594-607. [PMID: 24648497 PMCID: PMC4019491 DOI: 10.1091/mbc.e13-09-0553] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Heteromeric septin complexes serve as building blocks of filaments that organize the cortex of fungal and animal cells. This report addresses determinants that direct hetero-oligomerization of the 13 septin paralogues of mammals. It shows that three distinct septins direct assembly of tissue-specific heterotetramers. Septins are filament-forming proteins important for organizing the cortex of animal and fungal cells. In mammals, 13 septin paralogues were recently shown to assemble into core heterohexamer and heterooctamer complexes, which serve as building blocks for apolar filamentous structures that differ among cell types. To determine how tissue-specific septin paralogue expression may shape core heteromer repertoires and thereby modulate properties of septin filaments, we devised protocols to analyze native septin heteromers with distinct numbers of subunits. Our evidence based on genetically manipulated human cells supports and extends recent concepts of homology subgroup–restricted assembly into distinct categories of apolar heterohexamers and heterooctamers. We also identify a category of tetramers that have a subunit composition equivalent to an octameric building block. These atypical tetramers are prevalent in lymphocytes and neural tissues, in which octamers are abundant but hexamers are rare. Our results can be explained by tissue-specific expression of SEPT3 subgroup members: SEPT3, SEPT9, and SEPT12. These serve as cognate subunits in either heterooctamers or atypical tetramers but exhibit different preferences in various tissues. The identified tissue-specific repertoires of septin heteromers provide insights into how higher-order septin structures with differential properties and stabilities may form in diverse animal cell types.
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Affiliation(s)
- Mikael E Sellin
- Department of Molecular Biology, Umeå University, SE-901 87 Umeå, SwedenInstitute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Sonja Stenmark
- Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden
| | - Martin Gullberg
- Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden
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Brännström K, Lindhagen-Persson M, Gharibyan AL, Iakovleva I, Vestling M, Sellin ME, Brännström T, Morozova-Roche L, Forsgren L, Olofsson A. A generic method for design of oligomer-specific antibodies. PLoS One 2014; 9:e90857. [PMID: 24618582 PMCID: PMC3949727 DOI: 10.1371/journal.pone.0090857] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 02/06/2014] [Indexed: 01/07/2023] Open
Abstract
Antibodies that preferentially and specifically target pathological oligomeric protein and peptide assemblies, as opposed to their monomeric and amyloid counterparts, provide therapeutic and diagnostic opportunities for protein misfolding diseases. Unfortunately, the molecular properties associated with oligomer-specific antibodies are not well understood, and this limits targeted design and development. We present here a generic method that enables the design and optimisation of oligomer-specific antibodies. The method takes a two-step approach where discrimination between oligomers and fibrils is first accomplished through identification of cryptic epitopes exclusively buried within the structure of the fibrillar form. The second step discriminates between monomers and oligomers based on differences in avidity. We show here that a simple divalent mode of interaction, as within e.g. the IgG isotype, can increase the binding strength of the antibody up to 1500 times compared to its monovalent counterpart. We expose how the ability to bind oligomers is affected by the monovalent affinity and the turnover rate of the binding and, importantly, also how oligomer specificity is only valid within a specific concentration range. We provide an example of the method by creating and characterising a spectrum of different monoclonal antibodies against both the Aβ peptide and α-synuclein that are associated with Alzheimer's and Parkinson's diseases, respectively. The approach is however generic, does not require identification of oligomer-specific architectures, and is, in essence, applicable to all polypeptides that form oligomeric and fibrillar assemblies.
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Affiliation(s)
| | | | - Anna L. Gharibyan
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Irina Iakovleva
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Monika Vestling
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | | | | | | | - Lars Forsgren
- Department of Clinical Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden
| | - Anders Olofsson
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
- * E-mail:
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Vonaesch P, Cardini S, Sellin ME, Goud B, Hardt WD, Schauer K. Quantitative insights into actin rearrangements and bacterial target site selection from Salmonella Typhimurium infection of micropatterned cells. Cell Microbiol 2013; 15:1851-65. [PMID: 23648178 DOI: 10.1111/cmi.12154] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 04/10/2013] [Accepted: 04/28/2013] [Indexed: 12/31/2022]
Abstract
Reorganization of the host cell actin cytoskeleton is crucial during pathogen invasion. We established micropatterned cells as a standardized infection model for cell invasion to quantitatively study actin rearrangements triggered by Salmonella Typhimurium (S. Tm). Micropatterns of extracellular matrix proteins force cells to adopt a reproducible shape avoiding strong cell-to-cell variations, a major limitation in classical cell culture conditions. S. Tm induced F-actin-rich ruffles and invaded micropatterned cells similar to unconstrained cells. Yet, standardized conditions allowed fast and unbiased comparison of cellular changes triggered by the SipA and SopE bacterial effector proteins. Intensity measurements in defined regions revealed that the content of pre-existing F-actin remained unchanged during infection, suggesting that newly polymerized F-actin in bacteria-triggered ruffles originates from the G-actin pool. Analysing bacterial target sites, we found that bacteria did not show any preferences for the local actin cytoskeleton specificities. Rather, invasion was constrained to a specific 'cell height', due to flagella-mediated near-surface swimming. We found that invasion sites were similar to bacterial binding sites, indicating that S. Tm can induce a permissive invasion site wherever it binds. As micropatterned cells can be infected by many different pathogens they represent a valuable new tool for quantitative analysis of host-pathogen interactions.
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Affiliation(s)
- Pascale Vonaesch
- Institute of Microbiology, ETH Zürich, Wolfgang-Pauli-Str. 12, 8093, Zürich, Switzerland
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37
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Abstract
Cell type–specific alternative splicing results in six confirmed mammalian SEPT9 isoforms. SEPT9 expression levels dictate the hexamer-to-octamer ratio of septin core heteromers, and isoform compositions and expression levels together determine higher-order arrangements of septin filaments. Septin-family proteins assemble into rod-shaped heteromeric complexes that form higher-order arrangements at the cell cortex, where they serve apparently conserved functions as diffusion barriers and molecular scaffolds. There are 13 confirmed septin paralogues in mammals, which may be ubiquitous or tissue specific. Septin hetero-oligomerization appears homology subgroup directed, which in turn determines the subunit arrangement of six- to eight-subunit core heteromers. Here we address functional properties of human SEPT9, which, due to variable mRNA splicing, exists as multiple isoforms that differ between tissues. Myeloid K562 cells express three SEPT9 isoforms, all of which have an equal propensity to hetero-oligomerize with SEPT7-containing hexamers to generate octameric heteromers. However, due to limiting amounts of SEPT9, K562 cells contain both hexameric and octameric heteromers. To generate cell lines with controllable hexamer-to-octamer ratios and that express single SEPT9 isoforms, we developed a gene product replacement strategy. By this means we identified SEPT9 isoform–specific properties that either facilitate septin heteromer polymerization along microtubules or modulate the size range of submembranous septin disks—a prevalent septin structure in nonadhered cells. Our findings show that the SEPT9 expression level directs the hexamer-to-octamer ratio, and that the isoform composition and expression level together determine higher-order arrangements of septins.
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Affiliation(s)
- Mikael E Sellin
- Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden
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Abstract
Septin assemblies during the interphase of animal cells remain poorly defined and are the topic of this report. The data point to a general model for assembly of higher-order septin arrangements at locations providing the greatest opportunity for binding cooperativity, which depends on both the cell type and external cues. Septin family proteins oligomerize through guanosine 5′-triphosphate–binding domains into core heteromers, which in turn polymerize at the cleavage furrow of dividing fungal and animal cells. Septin assemblies during the interphase of animal cells remain poorly defined and are the topic of this report. In this study, we developed protocols for visualization of authentic higher-order assemblies using tagged septins to effectively replace the endogenous gene product within septin core heteromers in human cells. Our analysis revealed that septins assemble into microtubule-supported, disk-like structures at the plasma membrane. In the absence of cell substrate adhesion, this is the predominant higher-order arrangement in interphase cells and each of the seven to eight septin family members expressed by the two analyzed cell types appears equally represented. However, studies of myeloid and lymphoid cell model systems revealed cell type–specific alterations of higher-order septin arrangements in response to substrate adhesion. Live-cell observations suggested that all higher-order septin assemblies are mutually exclusive with plasma membrane regions undergoing remodeling. The combined data point to a mechanism by which densely arranged cortical microtubules, which are typical for nonadhered spherical cells, support plasma membrane–bound, disk-like septin assemblies.
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Affiliation(s)
- Mikael E Sellin
- Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden.
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Abstract
Vertebrates express 9–17 septin family members known to oligomerize into diverse structures, but their native assembly states have remained elusive. The results presented suggest a generic model for how the temporal order of septin assembly directs the subunit arrangement within distinct pools of six- to eight-subunit core heteromers. Septins are conserved GTP-binding proteins that assemble into lateral diffusion barriers and molecular scaffolds. Vertebrate genomes contain 9–17 septin genes that encode both ubiquitous and tissue-specific septins. Expressed septins may assemble in various combinations through both heterotypic and homotypic G-domain interactions. However, little is known regarding assembly states of mammalian septins and mechanisms directing ordered assembly of individual septins into heteromeric units, which is the focus of this study. Our analysis of the septin system in cells lacking or overexpressing selected septins reveals interdependencies coinciding with previously described homology subgroups. Hydrodynamic and single-particle data show that individual septins exist solely in the context of stable six- to eight-subunit core heteromers, all of which contain SEPT2 and SEPT6 subgroup members and SEPT7, while heteromers comprising more than six subunits also contain SEPT9. The combined data suggest a generic model for how the temporal order of septin assembly is homology subgroup-directed, which in turn determines the subunit arrangement of native heteromers. Because mammalian cells normally express multiple members and/or isoforms of some septin subgroups, our data also suggest that only a minor fraction of native heteromers are arranged as perfect palindromes.
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Affiliation(s)
- Mikael E Sellin
- Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden.
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Thorslund SE, Edgren T, Pettersson J, Nordfelth R, Sellin ME, Ivanova E, Francis MS, Isaksson EL, Wolf-Watz H, Fällman M. The RACK1 signaling scaffold protein selectively interacts with Yersinia pseudotuberculosis virulence function. PLoS One 2011; 6:e16784. [PMID: 21347310 PMCID: PMC3037380 DOI: 10.1371/journal.pone.0016784] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Accepted: 01/13/2011] [Indexed: 01/06/2023] Open
Abstract
Many gram-negative bacteria use type III secretion systems to translocate effector proteins into host cells. These effectors interfere with cellular functions in a highly regulated manner resulting in effects that are beneficial for the bacteria. The pathogen Yersinia can resist phagocytosis by eukaryotic cells by translocating Yop effectors into the target cell cytoplasm. This is called antiphagocytosis, and constitutes an important virulence feature of this pathogen since it allows survival in immune cell rich lymphoid organs. We show here that the virulence protein YopK has a role in orchestrating effector translocation necessary for productive antiphagocytosis. We present data showing that YopK influences Yop effector translocation by modulating the ratio of the pore-forming proteins YopB and YopD in the target cell membrane. Further, we show that YopK that can interact with the translocators, is exposed inside target cells and binds to the eukaryotic signaling protein RACK1. This protein is engaged upon Y. pseudotuberculosis-mediated β1-integrin activation and localizes to phagocytic cups. Cells with downregulated RACK1 levels are protected from antiphagocytosis. This resistance is not due to altered levels of translocated antiphagocytic effectors, and cells with reduced levels of RACK1 are still sensitive to the later occurring cytotoxic effect caused by the Yop effectors. Further, a yopK mutant unable to bind RACK1 shows an avirulent phenotype during mouse infection, suggesting that RACK1 targeting by YopK is a requirement for virulence. Together, our data imply that the local event of Yersinia-mediated antiphagocytosis involves a step where YopK, by binding RACK1, ensures an immediate specific spatial delivery of antiphagocytic effectors leading to productive inhibition of phagocytosis.
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Affiliation(s)
- Sara E. Thorslund
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Tomas Edgren
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | | | - Roland Nordfelth
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | | | | | - Matthew S. Francis
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Elin L. Isaksson
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Hans Wolf-Watz
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Maria Fällman
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
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Holmfeldt P, Sellin ME, Gullberg M. Upregulated Op18/stathmin activity causes chromosomal instability through a mechanism that evades the spindle assembly checkpoint. Exp Cell Res 2010; 316:2017-26. [PMID: 20399773 DOI: 10.1016/j.yexcr.2010.04.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 04/09/2010] [Accepted: 04/12/2010] [Indexed: 02/04/2023]
Abstract
Op18/stathmin (Op18) is a microtubule-destabilizing protein that is phosphorylation-inactivated during mitosis and its normal function is to govern tubulin subunit partitioning during interphase. Human tumors frequently overexpress Op18 and a tumor-associated Q18-->E mutation has been identified that confers hyperactivity, destabilizes spindle microtubules, and causes mitotic aberrancies, polyploidization, and chromosome loss in K562 leukemia cells. Here we determined whether wild-type and mutant Op18 have the potential to cause chromosomal instability by some means other than interference with spindle assembly, and thereby bypassing the spindle assembly checkpoint. Our approach was based on Op18 derivatives with distinct temporal order of activity during mitosis, conferred either by differential phosphorylation inactivation or by anaphase-specific degradation through fusion with the destruction box of cyclin B1. We present evidence that excessive Op18 activity generates chromosomal instability through interference occurring subsequent to the metaphase-to-anaphase transition, which reduces the fidelity of chromosome segregation to spindle poles during anaphase. Similar to uncorrected merotelic attachment, this mechanism evades detection by the spindle assembly checkpoint and thus provides an additional route to chromosomal instability.
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Affiliation(s)
- Per Holmfeldt
- Department of Molecular Biology, Umeå University, Umeå, Sweden
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Sellin ME, Holmfeldt P, Stenmark S, Gullberg M. Global regulation of the interphase microtubule system by abundantly expressed Op18/stathmin. Mol Biol Cell 2008; 19:2897-906. [PMID: 18434595 DOI: 10.1091/mbc.e08-01-0058] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Op18/stathmin (Op18), a conserved microtubule-depolymerizing and tubulin heterodimer-binding protein, is a major interphase regulator of tubulin monomer-polymer partitioning in diverse cell types in which Op18 is abundant. Here, we addressed the question of whether the microtubule regulatory function of Op18 includes regulation of tubulin heterodimer synthesis. We used two human cell model systems, K562 and Jurkat, combined with strategies for regulatable overexpression or depletion of Op18. Although Op18 depletion caused extensive overpolymerization and increased microtubule content in both cell types, we did not detect any alteration in polymer stability. Interestingly, however, we found that Op18 mediates positive regulation of tubulin heterodimer content in Jurkat cells, which was not observed in K562 cells. By analysis of cells treated with microtubule-poisoning drugs, we found that Jurkat cells regulate tubulin mRNA levels by a posttranscriptional mechanism similarly to normal primary cells, whereas this mechanism is nonfunctional in K562 cells. We present evidence that Op18 mediates posttranscriptional regulation of tubulin mRNA in Jurkat cells through the same basic autoregulatory mechanism as microtubule-poisoning drugs. This, combined with potent regulation of tubulin monomer-polymer partitioning, enables Op18 to exert global regulation of the microtubule system.
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Affiliation(s)
- Mikael E Sellin
- Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden
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Sellin ME, Holmfeldt P, Stenmark S, Gullberg M. Op18/Stathmin counteracts the activity of overexpressed tubulin-disrupting proteins in a human leukemia cell line. Exp Cell Res 2008; 314:1367-77. [PMID: 18262179 DOI: 10.1016/j.yexcr.2007.12.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Revised: 12/21/2007] [Accepted: 12/27/2007] [Indexed: 11/30/2022]
Abstract
Op18/stathmin (Op18) is a phosphorylation-regulated and differentially expressed microtubule-destabilizing protein in animal cells. Op18 regulates tubulin monomer-polymer partitioning of the interphase microtubule system and forms complexes with tubulin heterodimers. Recent reports have shown that specific tubulin-folding cofactors and related proteins may disrupt tubulin heterodimers. We therefore investigated whether Op18 protects unpolymerized tubulin from such disruptive activities. Our approach was based on inducible overexpression of two tubulin-disrupting proteins, namely TBCE, which is required for tubulin biogenesis, and E-like, which has been proposed to regulate tubulin turnover and microtubule stability. Expression of either of these proteins was found to cause a rapid degradation of both alpha-tubulin and beta-tubulin subunits of unpolymerized, but not polymeric, tubulin heterodimers. We found that depletion of Op18 by means of RNA interference increased the susceptibility of tubulin to TBCE or E-like mediated disruption, while overexpressed Op18 exerted a tubulin-protective effect. Tubulin protection was shown to depend on Op18 levels, binding affinity, and the partitioning between tubulin monomers and polymers. Hence, the present study reveals that Op18 at physiologically relevant levels functions to preserve the integrity of tubulin heterodimers, which may serve to regulate tubulin turnover rates.
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Affiliation(s)
- Mikael E Sellin
- Department of Molecular Biology, Umeå University, Umeå, Sweden.
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Holmfeldt P, Brännström K, Sellin ME, Segerman B, Carlsson SR, Gullberg M. The Schistosoma mansoni protein Sm16/SmSLP/SmSPO-1 is a membrane-binding protein that lacks the proposed microtubule-regulatory activity. Mol Biochem Parasitol 2007; 156:225-34. [PMID: 17913257 DOI: 10.1016/j.molbiopara.2007.08.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Revised: 08/21/2007] [Accepted: 08/21/2007] [Indexed: 11/25/2022]
Abstract
Sm16/SmSLP/SPO-1 (Sm16) has been identified as a developmentally regulated protein that is released from specific glands of the Schistosoma mansoni parasite during skin penetration. Sm16 has been ascribed both anti-inflammatory activities and a functional similarity with the conserved cytosolic tubulin-binding protein stathmin/Op18. Here we used a cell line to confirm signal peptide-dependent secretion and to define the secreted form of Sm16 for production in E. coli. We present evidence from both in vitro experiments and studies on transfected human cells that refute any functional similarity with stathmin/Op18. Instead of an Op18-like activity, we found that targeting of Sm16 to the cytosol of human cells, which was achieved by ectopic expression of Sm16 lacking the signal peptide, results in a caspase-dependent apoptotic response. Interestingly, by analysis of recombinant preparations we found that the secreted form of Sm16 is a lipid bilayer-binding protein that efficiently binds to the surface of diverse cell types by a polyanion-independent mechanism, which results in uptake by endocytosis. While the significance of the pro-apoptotic activity exerted by cytosolic Sm16 remains unclear, the present findings on cell-surface-binding properties of Sm16 seems likely to be of functional relevance during skin penetration of the parasite.
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Affiliation(s)
- Per Holmfeldt
- Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden.
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