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Chandra P, Philips JA. USP8 promotes intracellular infection by enhancing ESCRT-mediated membrane repair, limiting xenophagy, and reducing oxidative stress. Autophagy 2024:1-17. [PMID: 39178916 DOI: 10.1080/15548627.2024.2395134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 08/13/2024] [Accepted: 08/18/2024] [Indexed: 08/26/2024] Open
Abstract
The host ESCRT-machinery repairs damaged endolysosomal membranes. If damage persists, selective macroautophagy/autophagy clears the damaged compartment. Mycobacterium tuberculosis (Mtb) is an intracellular pathogen that damages the phagosomal membrane and targets ESCRT-mediated repair as part of its virulence program. The E3 ubiquitin ligases PRKN and SMURF1 promote autophagic capture of damaged, Mtb-containing phagosomes. Because ubiquitination is a reversible process, we anticipated that host deubiquitinases (DUBs) would also be involved. Here, we screened all predicted mouse DUBs for their role in ubiquitin targeting and control of intracellular Mtb. We show that USP8 (ubiquitin specific peptidase 8) colocalizes with intracellular Mtb, recognizes phagosomal membrane damage, and is required for ESCRT-dependent membrane repair. Furthermore, we show that USP8 regulates the NFE2L2/NRF2-dependent antioxidant signature. Taken together, our study demonstrates a central role of USP8 in promoting Mtb intracellular growth by promoting phagosomal membrane repair, limiting ubiquitin-driven selective autophagy, and reducing oxidative stress.Abbreviation: BMDMs: bone marrow-derived macrophages; CFUs: colony-forming units; DUB: deubiquitinase; ESCRT: endosomal sorting complexes required for transport; LLOMe: L-leucyl-L-leucine methyl ester; MFI: mean fluorescence intensity; MOI: multiplicity of infection; Mtb: Mycobacterium tuberculosis; NFE2L2/NRF2: nuclear factor, erythroid derived 2, like 2; PMA: phorbol 12-myristate 13-acetate; ROS: reactive oxygen species; USP8: ubiquitin specific peptidase 8.
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Affiliation(s)
- Pallavi Chandra
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Jennifer A Philips
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA
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2
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Vozandychova V, Rehulka P, Hercik K, Spidlova P, Pavlik P, Hanus J, Hadravova R, Stulik J. Modified activities of macrophages' deubiquitinating enzymes after Francisella infection. Front Immunol 2023; 14:1252827. [PMID: 37841261 PMCID: PMC10570801 DOI: 10.3389/fimmu.2023.1252827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 09/14/2023] [Indexed: 10/17/2023] Open
Abstract
Francisella tularensis influences several host molecular/signaling pathways during infection. Ubiquitination and deubiquitination are among the most important regulatory mechanisms and respectively occur through attachment or removal of the ubiquitin molecule. The process is necessary not only to mark molecules for degradation, but also, for example, to the activation of signaling pathways leading to pro-inflammatory host response. Many intracellular pathogens, including Francisella tularensis, have evolved mechanisms of modifying such host immune responses to escape degradation. Here, we describe that F. tularensis interferes with the host's ubiquitination system. We show increased total activity of deubiquitinating enzymes (DUBs) in human macrophages after infection, while confirm reduced enzymatic activities of two specific DUBs (USP10 and UCH-L5), and demonstrate increased activity of USP25. We further reveal the enrichment of these three enzymes in exosomes derived from F. tularensis-infected cells. The obtained results show the regulatory effect on ubiquitination mechanism in macrophages during F. tularensis infection.
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Affiliation(s)
- Vera Vozandychova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Pavel Rehulka
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Kamil Hercik
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czechia
| | - Petra Spidlova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Pavla Pavlik
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Jaroslav Hanus
- Department of Chemical Engineering, University of Chemistry and Technology, Prague, Czechia
| | - Romana Hadravova
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czechia
| | - Jiri Stulik
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
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3
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Aromolaran OT, Isewon I, Adedeji E, Oswald M, Adebiyi E, Koenig R, Oyelade J. Heuristic-enabled active machine learning: A case study of predicting essential developmental stage and immune response genes in Drosophila melanogaster. PLoS One 2023; 18:e0288023. [PMID: 37556452 PMCID: PMC10411809 DOI: 10.1371/journal.pone.0288023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 06/18/2023] [Indexed: 08/11/2023] Open
Abstract
Computational prediction of absolute essential genes using machine learning has gained wide attention in recent years. However, essential genes are mostly conditional and not absolute. Experimental techniques provide a reliable approach of identifying conditionally essential genes; however, experimental methods are laborious, time and resource consuming, hence computational techniques have been used to complement the experimental methods. Computational techniques such as supervised machine learning, or flux balance analysis are grossly limited due to the unavailability of required data for training the model or simulating the conditions for gene essentiality. This study developed a heuristic-enabled active machine learning method based on a light gradient boosting model to predict essential immune response and embryonic developmental genes in Drosophila melanogaster. We proposed a new sampling selection technique and introduced a heuristic function which replaces the human component in traditional active learning models. The heuristic function dynamically selects the unlabelled samples to improve the performance of the classifier in the next iteration. Testing the proposed model with four benchmark datasets, the proposed model showed superior performance when compared to traditional active learning models (random sampling and uncertainty sampling). Applying the model to identify conditionally essential genes, four novel essential immune response genes and a list of 48 novel genes that are essential in embryonic developmental condition were identified. We performed functional enrichment analysis of the predicted genes to elucidate their biological processes and the result evidence our predictions. Immune response and embryonic development related processes were significantly enriched in the essential immune response and embryonic developmental genes, respectively. Finally, we propose the predicted essential genes for future experimental studies and use of the developed tool accessible at http://heal.covenantuniversity.edu.ng for conditional essentiality predictions.
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Affiliation(s)
- Olufemi Tony Aromolaran
- Department of Computer & Information Sciences, Covenant University, Ota, Ogun State, Nigeria
- Covenant University Bioinformatics Research (CUBRe), Covenant University, Ota, Ogun State, Nigeria
| | - Itunu Isewon
- Department of Computer & Information Sciences, Covenant University, Ota, Ogun State, Nigeria
- Covenant University Bioinformatics Research (CUBRe), Covenant University, Ota, Ogun State, Nigeria
| | - Eunice Adedeji
- Covenant University Bioinformatics Research (CUBRe), Covenant University, Ota, Ogun State, Nigeria
- Department of Biochemistry, Covenant University, Ota, Ogun State, Nigeria
| | - Marcus Oswald
- Integrated Research and Treatment Center, Center for Sepsis Control and Care (CSCC), Jena University Hospital, Am Klinikum, Jena, Germany
- Institute of Infectious Diseases and Infection Control, Jena University Hospital, Am Klinikum, Jena, Germany
| | - Ezekiel Adebiyi
- Department of Computer & Information Sciences, Covenant University, Ota, Ogun State, Nigeria
- Covenant University Bioinformatics Research (CUBRe), Covenant University, Ota, Ogun State, Nigeria
| | - Rainer Koenig
- Integrated Research and Treatment Center, Center for Sepsis Control and Care (CSCC), Jena University Hospital, Am Klinikum, Jena, Germany
- Institute of Infectious Diseases and Infection Control, Jena University Hospital, Am Klinikum, Jena, Germany
| | - Jelili Oyelade
- Department of Computer & Information Sciences, Covenant University, Ota, Ogun State, Nigeria
- Covenant University Bioinformatics Research (CUBRe), Covenant University, Ota, Ogun State, Nigeria
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4
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Ma Z, Higgs M, Alqahtani M, Bakshi CS, Malik M. ThioredoxinA1 Controls the Oxidative Stress Response of Francisella tularensis Live Vaccine Strain (LVS). J Bacteriol 2022; 204:e0008222. [PMID: 35475633 PMCID: PMC9112935 DOI: 10.1128/jb.00082-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 04/01/2022] [Indexed: 11/20/2022] Open
Abstract
Francisella tularensis is an intracellular, Gram-negative bacterium known for causing a disease known as tularemia in the Northern Hemisphere. F. tularensis is classified as a category A select agent by the CDC based on its possible use as a bioterror agent. F. tularensis overcomes oxidative stress encountered during its growth in the environment or host macrophages by encoding antioxidant enzymes such as superoxide dismutases, catalase, and alkylhydroperoxy reductase. These antioxidant enzymes are regulated by the oxidative stress response regulator, OxyR. In addition to these antioxidant enzymes, F. tularensis also encodes two thioredoxins, TrxA1 (FTL_0611) and TrxA2 (FTL_1224); however, their role in the oxidative stress response of F. tularensis is not known. This study investigated the role of thioredoxins of F. tularensis in the oxidative stress response and intracellular survival. Our results demonstrate that TrxA1 but not TrxA2 plays a major role in the oxidative stress response of F. tularensis. Most importantly, this study elucidates a novel mechanism through which the TrxA1 of F. tularensis controls the oxidative stress response by regulating the expression of the master regulator, oxyR. Further, TrxA1 is required for the intramacrophage survival and growth of Francisella. Overall, this study describes a novel role of thioredoxin, TrxA1, in regulating the oxidative stress response of F. tularensis. IMPORTANCE The role of thioredoxins in the oxidative stress response of F. tularensis is not known. This study demonstrates that of the two thioredoxins, TrxA1 is vital to counter the oxidative stress in F. tularensis live vaccine strain (LVS). Furthermore, this study shows differences in the well-studied thioredoxins of Escherichia coli. First, the expression of TrxA1 of F. tularensis is independent of the oxidative stress response regulator, OxyR. Second and most importantly, TrxA1 regulates the expression of oxyR and, therefore, the OxyR-dependent oxidative stress response of F. tularensis. Overall, this study reports a novel regulatory role of TrxA1 of F. tularensis in the oxidative stress response.
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Affiliation(s)
- Zhuo Ma
- Department of Basic and Clinical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York, USA
| | - Matthew Higgs
- Department of Basic and Clinical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York, USA
| | - Maha Alqahtani
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, USA
| | - Chandra Shekhar Bakshi
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, USA
| | - Meenakshi Malik
- Department of Basic and Clinical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York, USA
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5
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Aromolaran O, Beder T, Adedeji E, Ajamma Y, Oyelade J, Adebiyi E, Koenig R. Predicting host dependency factors of pathogens in Drosophila melanogaster using machine learning. Comput Struct Biotechnol J 2021; 19:4581-4592. [PMID: 34471501 PMCID: PMC8385402 DOI: 10.1016/j.csbj.2021.08.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 08/06/2021] [Accepted: 08/06/2021] [Indexed: 11/25/2022] Open
Abstract
Pathogens causing infections, and particularly when invading the host cells, require the host cell machinery for efficient regeneration and proliferation during infection. For their life cycle, host proteins are needed and these Host Dependency Factors (HDF) may serve as therapeutic targets. Several attempts have approached screening for HDF producing large lists of potential HDF with, however, only marginal overlap. To get consistency into the data of these experimental studies, we developed a machine learning pipeline. As a case study, we used publicly available lists of experimentally derived HDF from twelve different screening studies based on gene perturbation in Drosophila melanogaster cells or in vivo upon bacterial or protozoan infection. A total of 50,334 gene features were generated from diverse categories including their functional annotations, topology attributes in protein interaction networks, nucleotide and protein sequence features, homology properties and subcellular localization. Cross-validation revealed an excellent prediction performance. All feature categories contributed to the model. Predicted and experimentally derived HDF showed a good consistency when investigating their common cellular processes and function. Cellular processes and molecular function of these genes were highly enriched in membrane trafficking, particularly in the trans-Golgi network, cell cycle and the Rab GTPase binding family. Using our machine learning approach, we show that HDF in organisms can be predicted with high accuracy evidencing their common investigated characteristics. We elucidated cellular processes which are utilized by invading pathogens during infection. Finally, we provide a list of 208 novel HDF proposed for future experimental studies.
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Affiliation(s)
- Olufemi Aromolaran
- Department of Computer & Information Sciences, Covenant University, Ota, Ogun State, Nigeria
- Integrated Research and Treatment Center, Center for Sepsis Control and Care (CSCC), Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
- Covenant University Bioinformatics Research (CUBRe), Covenant University, Ota, Ogun State, Nigeria
| | - Thomas Beder
- Integrated Research and Treatment Center, Center for Sepsis Control and Care (CSCC), Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
- Institute of Infectious Diseases and Infection Control, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
| | - Eunice Adedeji
- Covenant University Bioinformatics Research (CUBRe), Covenant University, Ota, Ogun State, Nigeria
- Department of Biochemistry, Covenant University, Ota, Ogun State, Nigeria
| | - Yvonne Ajamma
- Covenant University Bioinformatics Research (CUBRe), Covenant University, Ota, Ogun State, Nigeria
| | - Jelili Oyelade
- Department of Computer & Information Sciences, Covenant University, Ota, Ogun State, Nigeria
- Integrated Research and Treatment Center, Center for Sepsis Control and Care (CSCC), Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
- Covenant University Bioinformatics Research (CUBRe), Covenant University, Ota, Ogun State, Nigeria
| | - Ezekiel Adebiyi
- Department of Computer & Information Sciences, Covenant University, Ota, Ogun State, Nigeria
- Covenant University Bioinformatics Research (CUBRe), Covenant University, Ota, Ogun State, Nigeria
| | - Rainer Koenig
- Integrated Research and Treatment Center, Center for Sepsis Control and Care (CSCC), Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
- Institute of Infectious Diseases and Infection Control, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
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6
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Vozandychova V, Stojkova P, Hercik K, Rehulka P, Stulik J. The Ubiquitination System within Bacterial Host-Pathogen Interactions. Microorganisms 2021; 9:638. [PMID: 33808578 PMCID: PMC8003559 DOI: 10.3390/microorganisms9030638] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 03/15/2021] [Accepted: 03/16/2021] [Indexed: 12/17/2022] Open
Abstract
Ubiquitination of proteins, like phosphorylation and acetylation, is an important regulatory aspect influencing numerous and various cell processes, such as immune response signaling and autophagy. The study of ubiquitination has become essential to learning about host-pathogen interactions, and a better understanding of the detailed mechanisms through which pathogens affect ubiquitination processes in host cell will contribute to vaccine development and effective treatment of diseases. Pathogenic bacteria (e.g., Salmonella enterica, Legionella pneumophila and Shigella flexneri) encode many effector proteins, such as deubiquitinating enzymes (DUBs), targeting the host ubiquitin machinery and thus disrupting pertinent ubiquitin-dependent anti-bacterial response. We focus here upon the host ubiquitination system as an integral unit, its interconnection with the regulation of inflammation and autophagy, and primarily while examining pathogens manipulating the host ubiquitination system. Many bacterial effector proteins have already been described as being translocated into the host cell, where they directly regulate host defense processes. Due to their importance in pathogenic bacteria progression within the host, they are regarded as virulence factors essential for bacterial evasion. However, in some cases (e.g., Francisella tularensis) the host ubiquitination system is influenced by bacterial infection, although the responsible bacterial effectors are still unknown.
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Affiliation(s)
- Vera Vozandychova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 50001 Hradec Kralove, Czech Republic; (V.V.); (P.S.); (K.H.); (P.R.)
| | - Pavla Stojkova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 50001 Hradec Kralove, Czech Republic; (V.V.); (P.S.); (K.H.); (P.R.)
| | - Kamil Hercik
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 50001 Hradec Kralove, Czech Republic; (V.V.); (P.S.); (K.H.); (P.R.)
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo namesti 542/2, 16000 Prague, Czech Republic
| | - Pavel Rehulka
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 50001 Hradec Kralove, Czech Republic; (V.V.); (P.S.); (K.H.); (P.R.)
| | - Jiri Stulik
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 50001 Hradec Kralove, Czech Republic; (V.V.); (P.S.); (K.H.); (P.R.)
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7
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Daussy CF, Wodrich H. "Repair Me if You Can": Membrane Damage, Response, and Control from the Viral Perspective. Cells 2020; 9:cells9092042. [PMID: 32906744 PMCID: PMC7564661 DOI: 10.3390/cells9092042] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/03/2020] [Accepted: 09/04/2020] [Indexed: 12/13/2022] Open
Abstract
Cells are constantly challenged by pathogens (bacteria, virus, and fungi), and protein aggregates or chemicals, which can provoke membrane damage at the plasma membrane or within the endo-lysosomal compartments. Detection of endo-lysosomal rupture depends on a family of sugar-binding lectins, known as galectins, which sense the abnormal exposure of glycans to the cytoplasm upon membrane damage. Galectins in conjunction with other factors orchestrate specific membrane damage responses such as the recruitment of the endosomal sorting complex required for transport (ESCRT) machinery to either repair damaged membranes or the activation of autophagy to remove membrane remnants. If not controlled, membrane damage causes the release of harmful components including protons, reactive oxygen species, or cathepsins that will elicit inflammation. In this review, we provide an overview of current knowledge on membrane damage and cellular responses. In particular, we focus on the endo-lysosomal damage triggered by non-enveloped viruses (such as adenovirus) and discuss viral strategies to control the cellular membrane damage response. Finally, we debate the link between autophagy and inflammation in this context and discuss the possibility that virus induced autophagy upon entry limits inflammation.
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8
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Bradford MK, Elkins KL. Immune lymphocytes halt replication of Francisella tularensis LVS within the cytoplasm of infected macrophages. Sci Rep 2020; 10:12023. [PMID: 32694562 PMCID: PMC7374111 DOI: 10.1038/s41598-020-68798-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 06/26/2020] [Indexed: 12/18/2022] Open
Abstract
Francisella tularensis is a highly infectious intracellular bacterium that causes tularemia by invading and replicating in mammalian myeloid cells. Francisella primarily invades host macrophages, where it escapes phagosomes within a few hours and replicates in the cytoplasm. Less is known about how Francisella traffics within macrophages or exits into the extracellular environment for further infection. Immune T lymphocytes control the replication of Francisella within macrophages in vitro by a variety of mechanisms, but nothing is known about intracellular bacterial trafficking in the face of such immune pressure. Here we used a murine model of infection with a Francisella attenuated live vaccine strain (LVS), which is under study as a human vaccine, to evaluate the hypothesis that immune T cells control intramacrophage bacterial growth by re-directing bacteria into toxic intracellular compartments of infected macrophages. We visualized the interactions of lymphocytes and LVS-infected macrophages using confocal microscopy and characterized LVS intramacrophage trafficking when co-cultured with immune lymphocytes. We focused on the late stages of infection after bacteria escape from phagosomes, through bacterial replication and the death of macrophages. We found that the majority of LVS remained cytosolic in the absence of immune pressure, eventually resulting in macrophage death. In contrast, co-culture of LVS-infected macrophages with LVS-immune lymphocytes halted LVS replication and inhibited the spread of LVS infection between macrophages, but bacteria did not return to vacuoles such as lysosomes or autophagosomes and macrophages did not die. Therefore, immune lymphocytes directly limit intracellular bacterial replication within the cytoplasm of infected macrophages.
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Affiliation(s)
- Mary Katherine Bradford
- Laboratory of Mucosal Pathogens and Cellular Immunology, Division of Bacterial, Parasitic and Allergenic Products, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA.,Johns Hopkins University Professional Development and Career Office, 1830 E. Monument, 2-107, Baltimore, MD, 21287, USA
| | - Karen L Elkins
- Laboratory of Mucosal Pathogens and Cellular Immunology, Division of Bacterial, Parasitic and Allergenic Products, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA.
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9
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Gregory DJ, DeLoid GM, Salmon SL, Metzger DW, Kramnik I, Kobzik L. SON DNA-binding protein mediates macrophage autophagy and responses to intracellular infection. FEBS Lett 2020; 594:2782-2799. [PMID: 32484234 DOI: 10.1002/1873-3468.13851] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Accepted: 05/11/2020] [Indexed: 12/09/2022]
Abstract
Intracellular pathogens affect diverse host cellular defence and metabolic pathways. Here, we used infection with Francisella tularensis to identify SON DNA-binding protein as a central determinant of macrophage activities. RNAi knockdown of SON increases survival of human macrophages following F. tularensis infection or inflammasome stimulation. SON is required for macrophage autophagy, interferon response factor 3 expression, type I interferon response and inflammasome-associated readouts. SON knockdown has gene- and stimulus-specific effects on inflammatory gene expression. SON is required for accurate splicing and expression of GBF1, a key mediator of cis-Golgi structure and function. Chemical GBF1 inhibition has similar effects to SON knockdown, suggesting that SON controls macrophage functions at least in part by controlling Golgi-associated processes.
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Affiliation(s)
- David J Gregory
- Molecular and Physiological Sciences Program, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA.,Pediatric Infectious Disease, Massachusetts General Hospital, Boston, MA, USA
| | - Glen M DeLoid
- Molecular and Physiological Sciences Program, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Sharon L Salmon
- Department of Immunology and Microbial Disease, Albany Medical College, Albany, NY, USA
| | - Dennis W Metzger
- Department of Immunology and Microbial Disease, Albany Medical College, Albany, NY, USA
| | - Igor Kramnik
- Pulmonary Center, Department of Medicine, National Emerging Infectious Diseases Laboratories, Boston University School of Medicine, MA, USA
| | - Lester Kobzik
- Molecular and Physiological Sciences Program, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA
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10
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Duplantier AJ, Shurtleff AC, Miller C, Chiang CY, Panchal RG, Sunay M. Combating biothreat pathogens: ongoing efforts for countermeasure development and unique challenges. DRUG DISCOVERY TARGETING DRUG-RESISTANT BACTERIA 2020. [PMCID: PMC7258707 DOI: 10.1016/b978-0-12-818480-6.00007-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Research to discover and develop antibacterial and antiviral drugs with potent activity against pathogens of biothreat concern presents unique methodological and process-driven challenges. Herein, we review laboratory approaches for finding new antibodies, antibiotics, and antiviral molecules for pathogens of biothreat concern. Using high-throughput screening techniques, molecules that directly inhibit a pathogen’s entry, replication, or growth can be identified. Alternatively, molecules that target host proteins can be interesting targets for development when countering biothreat pathogens, due to the modulation of the host immune response or targeting proteins that interfere with the pathways required by the pathogen for replication. Monoclonal and cocktail antibody therapies approved by the Food and Drug Administration for countering anthrax and under development for treatment of Ebola virus infection are discussed. A comprehensive tabular review of current in vitro, in vivo, pharmacokinetic and efficacy datasets has been presented for biothreat pathogens of greatest concern. Finally, clinical trials and animal rule or traditional drug approval pathways are also reviewed. Opinions; interpretations; conclusions; and recommendations are those of the authors and are not necessarily endorsed by the US Army.
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11
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Viswanatha R, Brathwaite R, Hu Y, Li Z, Rodiger J, Merckaert P, Chung V, Mohr SE, Perrimon N. Pooled CRISPR Screens in Drosophila Cells. CURRENT PROTOCOLS IN MOLECULAR BIOLOGY 2019; 129:e111. [PMID: 31763777 PMCID: PMC6961806 DOI: 10.1002/cpmb.111] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
High-throughput screens in Drosophila melanogaster cell lines have led to discovery of conserved gene functions related to signal transduction, host-pathogen interactions, ion transport, and more. CRISPR/Cas9 technology has opened the door to new types of large-scale cell-based screens. Whereas array-format screens require liquid handling automation and assay miniaturization, pooled-format screens, in which reagents are introduced at random and in bulk, can be done in a standard lab setting. We provide a detailed protocol for conducting and evaluating genome-wide CRISPR single guide RNA (sgRNA) pooled screens in Drosophila S2R+ cultured cells. Specifically, we provide step-by-step instructions for library design and production, optimization of cytotoxin-based selection assays, genome-scale screening, and data analysis. This type of project takes ∼3 months to complete. Results can be used in follow-up studies performed in vivo in Drosophila, mammalian cells, and/or other systems. © 2019 by John Wiley & Sons, Inc. Basic Protocol: Pooled-format screening with Cas9-expressing Drosophila S2R+ cells in the presence of cytotoxin Support Protocol 1: Optimization of cytotoxin concentration for Drosophila cell screening Support Protocol 2: CRISPR sgRNA library design and production for Drosophila cell screening Support Protocol 3: Barcode deconvolution and analysis of screening data.
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Affiliation(s)
| | - Roderick Brathwaite
- Department of Genetics, Harvard Medical School, Boston, Massachusetts
- Drosophila RNAi Screening Center, Harvard Medical School, Boston, Massachusetts
| | - Yanhui Hu
- Department of Genetics, Harvard Medical School, Boston, Massachusetts
- Drosophila RNAi Screening Center, Harvard Medical School, Boston, Massachusetts
| | - Zhongchi Li
- Department of Genetics, Harvard Medical School, Boston, Massachusetts
| | - Jonathan Rodiger
- Department of Genetics, Harvard Medical School, Boston, Massachusetts
- Drosophila RNAi Screening Center, Harvard Medical School, Boston, Massachusetts
| | - Pierre Merckaert
- Department of Genetics, Harvard Medical School, Boston, Massachusetts
- Drosophila RNAi Screening Center, Harvard Medical School, Boston, Massachusetts
| | - Verena Chung
- Department of Genetics, Harvard Medical School, Boston, Massachusetts
- Drosophila RNAi Screening Center, Harvard Medical School, Boston, Massachusetts
| | - Stephanie E Mohr
- Department of Genetics, Harvard Medical School, Boston, Massachusetts
- Drosophila RNAi Screening Center, Harvard Medical School, Boston, Massachusetts
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, Boston, Massachusetts
- Drosophila RNAi Screening Center, Harvard Medical School, Boston, Massachusetts
- Howard Hughes Medical Institute, Boston, Massachusetts
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12
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Screen for fitness and virulence factors of Francisella sp. strain W12-1067 using amoebae. Int J Med Microbiol 2019; 309:151341. [PMID: 31451389 DOI: 10.1016/j.ijmm.2019.151341] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 07/17/2019] [Accepted: 08/18/2019] [Indexed: 11/21/2022] Open
Abstract
Francisella tularensis is the causative agent of the human disease referred to as tularemia. Other Francisella species are known but less is understood about their virulence factors. The role of environmental amoebae in the life-cycle of Francisella is still under discussion. Francisella sp. strain W12-1067 (F-W12) is an environmental Francisella isolate recently identified in Germany which is negative for the Francisella pathogenicity island, but exhibits a putative alternative type VI secretion system. Putative virulence factors have been identified in silico in the genome of F-W12. In this work, we established a "scatter screen", used earlier for pathogenic Legionella, to verify experimentally and identify candidate fitness factors using a transposon mutant bank of F-W12 and Acanthamoeba lenticulata as host organism. In these experiments, we identified 79 scatter clones (amoeba sensitive), which were further analyzed by an infection assay identifying 9 known virulence factors, but also candidate fitness factors of F-W12 not yet described as fitness factors in Francisella. The majority of the identified genes encoded proteins involved in the synthesis or maintenance of the cell envelope (LPS, outer membrane, capsule) or in the metabolism (glycolysis, gluconeogenesis, pentose phosphate pathway). Further 13C-flux analysis of the Tn5 glucokinase mutant strain revealed that the identified gene indeed encodes the sole active glucokinase in F-W12. In conclusion, candidate fitness factors of the new Francisella species F-W12 were identified using the scatter screen method which might also be usable for other Francisella species.
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13
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Kubelkova K, Macela A. Innate Immune Recognition: An Issue More Complex Than Expected. Front Cell Infect Microbiol 2019; 9:241. [PMID: 31334134 PMCID: PMC6616152 DOI: 10.3389/fcimb.2019.00241] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 06/18/2019] [Indexed: 12/11/2022] Open
Abstract
Primary interaction of an intracellular bacterium with its host cell is initiated by activation of multiple signaling pathways in response to bacterium recognition itself or as cellular responses to stress induced by the bacterium. The leading molecules in these processes are cell surface membrane receptors as well as cytosolic pattern recognition receptors recognizing pathogen-associated molecular patterns or damage-associated molecular patterns induced by the invading bacterium. In this review, we demonstrate possible sequences of events leading to recognition of Francisella tularensis, present findings on known mechanisms for manipulating cell responses to protect Francisella from being killed, and discuss newly published data from the perspective of early stages of host-pathogen interaction.
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Affiliation(s)
- Klara Kubelkova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
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14
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Grobler Y, Yun CY, Kahler DJ, Bergman CM, Lee H, Oliver B, Lehmann R. Whole genome screen reveals a novel relationship between Wolbachia levels and Drosophila host translation. PLoS Pathog 2018; 14:e1007445. [PMID: 30422992 PMCID: PMC6258568 DOI: 10.1371/journal.ppat.1007445] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Revised: 11/27/2018] [Accepted: 10/30/2018] [Indexed: 11/29/2022] Open
Abstract
Wolbachia is an intracellular bacterium that infects a remarkable range of insect hosts. Insects such as mosquitos act as vectors for many devastating human viruses such as Dengue, West Nile, and Zika. Remarkably, Wolbachia infection provides insect hosts with resistance to many arboviruses thereby rendering the insects ineffective as vectors. To utilize Wolbachia effectively as a tool against vector-borne viruses a better understanding of the host-Wolbachia relationship is needed. To investigate Wolbachia-insect interactions we used the Wolbachia/Drosophila model that provides a genetically tractable system for studying host-pathogen interactions. We coupled genome-wide RNAi screening with a novel high-throughput fluorescence in situ hybridization (FISH) assay to detect changes in Wolbachia levels in a Wolbachia-infected Drosophila cell line JW18. 1117 genes altered Wolbachia levels when knocked down by RNAi of which 329 genes increased and 788 genes decreased the level of Wolbachia. Validation of hits included in depth secondary screening using in vitro RNAi, Drosophila mutants, and Wolbachia-detection by DNA qPCR. A diverse set of host gene networks was identified to regulate Wolbachia levels and unexpectedly revealed that perturbations of host translation components such as the ribosome and translation initiation factors results in increased Wolbachia levels both in vitro using RNAi and in vivo using mutants and a chemical-based translation inhibition assay. This work provides evidence for Wolbachia-host translation interaction and strengthens our general understanding of the Wolbachia-host intracellular relationship.
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Affiliation(s)
- Yolande Grobler
- Department of Cell Biology, Howard Hughes Medical Institute and Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY, United States of America
| | - Chi Y. Yun
- High Throughput Biology Core, Skirball Institute at New York University Langone Medical Center, New York, NY, United States of America
| | - David J. Kahler
- High Throughput Biology Core, Skirball Institute at New York University Langone Medical Center, New York, NY, United States of America
| | - Casey M. Bergman
- Department of Genetics and Institute of Bioinformatics, University of Georgia, Athens, GA, United States of America
| | - Hangnoh Lee
- Section of Developmental Genomics, Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, United States of America
| | - Brian Oliver
- Section of Developmental Genomics, Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, United States of America
| | - Ruth Lehmann
- Department of Cell Biology, Howard Hughes Medical Institute and Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY, United States of America
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15
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Yersinia pestis Targets the Host Endosome Recycling Pathway during the Biogenesis of the Yersinia-Containing Vacuole To Avoid Killing by Macrophages. mBio 2018; 9:mBio.01800-17. [PMID: 29463656 PMCID: PMC5821078 DOI: 10.1128/mbio.01800-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Yersinia pestis has evolved many strategies to evade the innate immune system. One of these strategies is the ability to survive within macrophages. Upon phagocytosis, Y. pestis prevents phagolysosome maturation and establishes a modified compartment termed the Yersinia-containing vacuole (YCV). Y. pestis actively inhibits the acidification of this compartment, and eventually, the YCV transitions from a tight-fitting vacuole into a spacious replicative vacuole. The mechanisms to generate the YCV have not been defined. However, we hypothesized that YCV biogenesis requires Y. pestis interactions with specific host factors to subvert normal vesicular trafficking. In order to identify these factors, we performed a genome-wide RNA interference (RNAi) screen to identify host factors required for Y. pestis survival in macrophages. This screen revealed that 71 host proteins are required for intracellular survival of Y. pestis. Of particular interest was the enrichment for genes involved in endosome recycling. Moreover, we demonstrated that Y. pestis actively recruits Rab4a and Rab11b to the YCV in a type three secretion system-independent manner, indicating remodeling of the YCV by Y. pestis to resemble a recycling endosome. While recruitment of Rab4a was necessary to inhibit YCV acidification and lysosomal fusion early during infection, Rab11b appeared to contribute to later stages of YCV biogenesis. We also discovered that Y. pestis disrupts global host endocytic recycling in macrophages, possibly through sequestration of Rab11b, and this process is required for bacterial replication. These data provide the first evidence that Y. pestis targets the host endocytic recycling pathway to avoid phagolysosomal maturation and generate the YCV. Yersinia pestis can infect and survive within macrophages. However, the mechanisms that the bacterium use to subvert killing by these phagocytes have not been defined. To provide a better understanding of these mechanisms, we used an RNAi approach to identify host factors required for intracellular Y. pestis survival. This approach revealed that the host endocytic recycling pathway is essential for Y. pestis to avoid clearance by the macrophage. We further demonstrate that Y. pestis remodels the phagosome to resemble a recycling endosome, allowing the bacterium to avoid the normal phagolysosomal maturation pathway. Moreover, we show that infection with Y. pestis disrupts normal recycling in the macrophage and that disruption is required for bacterial replication. These findings provide the first evidence that Y. pestis targets the host endocytic recycling pathway in order to evade killing by macrophages.
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16
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Brenz Y, Winther-Larsen HC, Hagedorn M. Expanding Francisella models: Pairing up the soil amoeba Dictyostelium with aquatic Francisella. Int J Med Microbiol 2017; 308:32-40. [PMID: 28843671 DOI: 10.1016/j.ijmm.2017.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/31/2017] [Accepted: 08/04/2017] [Indexed: 12/19/2022] Open
Abstract
The bacterial genus Francisella comprises highly pathogenic species that infect mammals, arthropods, fish and protists. Understanding virulence and host defense mechanisms of Francisella infection relies on multiple animal and cellular model systems. In this review, we want to summarize the most commonly used Francisella host model platforms and highlight novel, alternative model systems using aquatic Francisella species. Established mouse and macrophage models contributed extensively to our understanding of Francisella infection. However, murine and human cells display significant differences in their response to Francisella infection. The zebrafish and the amoeba Dictyostelium are well-established model systems for host-pathogen interactions and open up opportunities to investigate bacterial virulence and host defense. Comparisons between model systems using human and fish pathogenic Francisella species revealed shared virulence strategies and pathology between them. Hence, zebrafish and Dictyostelium might complement current model systems to find new vaccine candidates and contribute to our understanding of Francisella infection.
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Affiliation(s)
- Yannick Brenz
- Department of Parasitology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359 Hamburg, Germany.
| | - Hanne C Winther-Larsen
- Centre for Integrative Microbial Evolution (CIME) and Department of Pharmaceutical Biosciences, University of Oslo, Sem Sælands vei 3, 0371 Oslo, Norway.
| | - Monica Hagedorn
- Department of Life Sciences and Chemistry, Jacobs University, Campus Ring 1, 28759 Bremen, Germany.
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17
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Reliance of Wolbachia on High Rates of Host Proteolysis Revealed by a Genome-Wide RNAi Screen of Drosophila Cells. Genetics 2017; 205:1473-1488. [PMID: 28159754 DOI: 10.1534/genetics.116.198903] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 01/27/2017] [Indexed: 11/18/2022] Open
Abstract
Wolbachia are gram-negative, obligate, intracellular bacteria carried by a majority of insect species worldwide. Here we use a Wolbachia-infected Drosophila cell line and genome-wide RNA interference (RNAi) screening to identify host factors that influence Wolbachia titer. By screening an RNAi library targeting 15,699 transcribed host genes, we identified 36 candidate genes that dramatically reduced Wolbachia titer and 41 that increased Wolbachia titer. Host gene knockdowns that reduced Wolbachia titer spanned a broad array of biological pathways including genes that influenced mitochondrial function and lipid metabolism. In addition, knockdown of seven genes in the host ubiquitin and proteolysis pathways significantly reduced Wolbachia titer. To test the in vivo relevance of these results, we found that drug and mutant inhibition of proteolysis reduced levels of Wolbachia in the Drosophila oocyte. The presence of Wolbachia in either cell lines or oocytes dramatically alters the distribution and abundance of ubiquitinated proteins. Functional studies revealed that maintenance of Wolbachia titer relies on an intact host Endoplasmic Reticulum (ER)-associated protein degradation pathway (ERAD). Accordingly, electron microscopy studies demonstrated that Wolbachia is intimately associated with the host ER and dramatically alters the morphology of this organelle. Given Wolbachia lack essential amino acid biosynthetic pathways, the reliance of Wolbachia on high rates of host proteolysis via ubiquitination and the ERAD pathways may be a key mechanism for provisioning Wolbachia with amino acids. In addition, the reliance of Wolbachia on the ERAD pathway and disruption of ER morphology suggests a previously unsuspected mechanism for Wolbachia's potent ability to prevent RNA virus replication.
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18
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Miller C, Celli J. Avoidance and Subversion of Eukaryotic Homeostatic Autophagy Mechanisms by Bacterial Pathogens. J Mol Biol 2016; 428:3387-98. [PMID: 27456933 PMCID: PMC5010449 DOI: 10.1016/j.jmb.2016.07.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 07/07/2016] [Accepted: 07/08/2016] [Indexed: 12/31/2022]
Abstract
Autophagy is a conserved lysosomal recycling process, which maintains cellular homeostasis during stress and starvation conditions by degrading and recycling proteins, lipids, and carbohydrates, ultimately increasing nutrient availability in eukaryotes. An additional function of autophagy, termed xenophagy, is to detect, capture, and destroy invading microorganisms, such as viruses, bacteria, and protozoa, providing autophagy with a role in innate immunity. Many intracellular pathogens have, however, developed mechanisms to avoid xenophagy and have evolved strategies to take advantage of select autophagic processes to undergo their intracellular life cycle. This review article will discuss the molecular mechanisms used by the intracellular bacterial pathogens Francisella spp. and Brucella spp. to manipulate components of the autophagic pathway, promoting cytosolic growth in the case of Francisella spp. and facilitating cellular egress and cell-to-cell spread in the case of Brucella spp. These examples highlight how successful, highly infectious bacterial pathogens avoid or subvert host autophagy mechanisms normally employed to maintain eukaryotic homeostasis.
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Affiliation(s)
- Cheryl Miller
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, 99164-7090 WA, USA.
| | - Jean Celli
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, 99164-7090 WA, USA.
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19
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Mellouk N, Enninga J. Cytosolic Access of Intracellular Bacterial Pathogens: The Shigella Paradigm. Front Cell Infect Microbiol 2016; 6:35. [PMID: 27092296 PMCID: PMC4820437 DOI: 10.3389/fcimb.2016.00035] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 03/14/2016] [Indexed: 12/20/2022] Open
Abstract
Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it.
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Affiliation(s)
- Nora Mellouk
- Dynamics of Host-Pathogen Interactions Unit, Institut Pasteur Paris, France
| | - Jost Enninga
- Dynamics of Host-Pathogen Interactions Unit, Institut Pasteur Paris, France
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20
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Straskova A, Spidlova P, Mou S, Worsham P, Putzova D, Pavkova I, Stulik J. Francisella tularensis type B ΔdsbA mutant protects against type A strain and induces strong inflammatory cytokine and Th1-like antibody response in vivo. Pathog Dis 2015; 73:ftv058. [PMID: 26253078 DOI: 10.1093/femspd/ftv058] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2015] [Indexed: 11/13/2022] Open
Abstract
Francisella tularensis subspecies tularensis is a highly virulent intracellular bacterial pathogen, causing the disease tularemia. However, a safe and effective vaccine for routine application against F. tularensis has not yet been developed. We have recently constructed the deletion mutants for the DsbA homolog protein (ΔdsbA/FSC200) and a hypothetical protein IglH (ΔiglH/FSC200) in the type B F. tularensis subsp. holarctica FSC200 strain, which exerted different protection capacity against parental virulent strain. In this study, we further investigated the immunological correlates for these different levels of protection provided by ΔdsbA/FSC200 and ΔiglH/FSC200 mutants. Our results show that ΔdsbA/FSC200 mutant, but not ΔiglH/FSC200 mutant, induces an early innate inflammatory response leading to strong Th1-like antibody response. Furthermore, vaccination with ΔdsbA/FSC200 mutant, but not with ΔiglH/FSC200, elicited protection against the subsequent challenge with type A SCHU S4 strain in mice. An immunoproteomic approach was used to map a spectrum of antigens targeted by Th1-like specific antibodies, and more than 80 bacterial antigens, including novel ones, were identified. Comparison of tularemic antigens recognized by the ΔdsbA/FSC200 post-vaccination and the SCHU S4 post-challenge sera then revealed the existence of 22 novel SCHU S4 specific antibody clones.
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Affiliation(s)
- Adela Straskova
- Department of Molecular Pathology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Trebesska 1575, Hradec Kralove 500 01, Czech Republic
| | - Petra Spidlova
- Department of Molecular Pathology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Trebesska 1575, Hradec Kralove 500 01, Czech Republic
| | - Sherry Mou
- Bacteriology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702-5011, USA
| | - Patricia Worsham
- Bacteriology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702-5011, USA
| | - Daniela Putzova
- Department of Molecular Pathology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Trebesska 1575, Hradec Kralove 500 01, Czech Republic
| | - Ivona Pavkova
- Department of Molecular Pathology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Trebesska 1575, Hradec Kralove 500 01, Czech Republic
| | - Jiri Stulik
- Department of Molecular Pathology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Trebesska 1575, Hradec Kralove 500 01, Czech Republic
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21
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Santos JC, Duchateau M, Fredlund J, Weiner A, Mallet A, Schmitt C, Matondo M, Hourdel V, Chamot-Rooke J, Enninga J. The COPII complex and lysosomal VAMP7 determine intracellular Salmonella localization and growth. Cell Microbiol 2015; 17:1699-720. [PMID: 26084942 DOI: 10.1111/cmi.12475] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 05/22/2015] [Accepted: 06/12/2015] [Indexed: 12/18/2022]
Abstract
Salmonella invades epithelial cells and survives within a membrane-bound compartment, the Salmonella-containing vacuole (SCV). We isolated and determined the host protein composition of the SCV at 30 min and 3 h of infection to identify and characterize novel regulators of intracellular bacterial localization and growth. Quantitation of the SCV protein content revealed 392 host proteins specifically enriched at SCVs, out of which 173 associated exclusively with early SCVs, 124 with maturing SCV and 95 proteins during both time-points. Vacuole interactions with endoplasmic reticulum-derived coat protein complex II vesicles modulate early steps of SCV maturation, promoting SCV rupture and bacterial hyper-replication within the host cytosol. On the other hand, SCV interactions with VAMP7-positive lysosome-like vesicles promote Salmonella-induced filament formation and bacterial growth within the late SCV. Our results reveal that the dynamic communication between the SCV and distinct host organelles affects both intracellular Salmonella localization and growth at successive steps of host cell invasion.
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Affiliation(s)
- José Carlos Santos
- Unit of Dynamics of Host-Pathogen Interactions, Institut Pasteur, Paris, France.,Graduate Program in Areas of Basic and Applied Biology (GABBA), University of Porto, Porto, Portugal
| | - Magalie Duchateau
- Structural Mass Spectrometry and Proteomics Unit, Institut Pasteur, Paris, France
| | - Jennifer Fredlund
- Unit of Dynamics of Host-Pathogen Interactions, Institut Pasteur, Paris, France
| | - Allon Weiner
- Unit of Dynamics of Host-Pathogen Interactions, Institut Pasteur, Paris, France
| | - Adeline Mallet
- Plate-forme Microscopie Ultrastructurale, Institut Pasteur, Paris, France
| | - Christine Schmitt
- Plate-forme Microscopie Ultrastructurale, Institut Pasteur, Paris, France
| | - Mariette Matondo
- Structural Mass Spectrometry and Proteomics Unit, Institut Pasteur, Paris, France
| | - Véronique Hourdel
- Structural Mass Spectrometry and Proteomics Unit, Institut Pasteur, Paris, France
| | - Julia Chamot-Rooke
- Structural Mass Spectrometry and Proteomics Unit, Institut Pasteur, Paris, France.,CNRS UMR3528, Paris, France
| | - Jost Enninga
- Unit of Dynamics of Host-Pathogen Interactions, Institut Pasteur, Paris, France
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22
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Mellouk N, Weiner A, Aulner N, Schmitt C, Elbaum M, Shorte SL, Danckaert A, Enninga J. Shigella subverts the host recycling compartment to rupture its vacuole. Cell Host Microbe 2015; 16:517-30. [PMID: 25299335 DOI: 10.1016/j.chom.2014.09.005] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 07/21/2014] [Accepted: 08/12/2014] [Indexed: 01/01/2023]
Abstract
Shigella enters epithlial cells via internalization into a vacuole. Subsequent vacuolar membrane rupture allows bacterial escape into the cytosol for replication and cell-to-cell spread. Bacterial effectors such as IpgD, a PI(4,5)P2 phosphatase that generates PI(5)P and alters host actin, facilitate this internalization. Here, we identify host proteins involved in Shigella uptake and vacuolar membrane rupture by high-content siRNA screening and subsequently focus on Rab11, a constituent of the recycling compartment. Rab11-positive vesicles are recruited to the invasion site before vacuolar rupture, and Rab11 knockdown dramatically decreases vacuolar membrane rupture. Additionally, Rab11 recruitment is absent and vacuolar rupture is delayed in the ipgD mutant that does not dephosphorylate PI(4,5)P₂ into PI(5)P. Ultrastructural analyses of Rab11-positive vesicles further reveal that ipgD mutant-containing vacuoles become confined in actin structures that likely contribute to delayed vacular rupture. These findings provide insight into the underlying molecular mechanism of vacuole progression and rupture during Shigella invasion.
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Affiliation(s)
- Nora Mellouk
- Institut Pasteur, Dynamics of Host-Pathogen interactions Unit, 25 Rue du Dr. Roux, 75724 Paris, France
| | - Allon Weiner
- Institut Pasteur, Dynamics of Host-Pathogen interactions Unit, 25 Rue du Dr. Roux, 75724 Paris, France
| | - Nathalie Aulner
- Institut Pasteur, Imagopole, 28 Rue du Dr. Roux, 75724 Paris, France
| | - Christine Schmitt
- Institut Pasteur, Imagopole, 28 Rue du Dr. Roux, 75724 Paris, France
| | - Michael Elbaum
- Department of Materials and Interfaces, Weizmann Institute of Sciences, 234 Herzl Street, Rehovot 76100, Israel
| | - Spencer L Shorte
- Institut Pasteur, Imagopole, 28 Rue du Dr. Roux, 75724 Paris, France
| | - Anne Danckaert
- Institut Pasteur, Imagopole, 28 Rue du Dr. Roux, 75724 Paris, France.
| | - Jost Enninga
- Institut Pasteur, Dynamics of Host-Pathogen interactions Unit, 25 Rue du Dr. Roux, 75724 Paris, France.
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23
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Yan Q, Zhu H, Wang FH, Feng JY, Wang WQ, Shi X, Zhou YP, Zhang X, Sun XD. Inhibition of TRB3 Protects Photoreceptors against Endoplasmic Reticulum Stress-Induced Apoptosis after Experimental Retinal Detachment. Curr Eye Res 2015; 41:240-8. [DOI: 10.3109/02713683.2015.1006371] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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24
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Fauvarque MO. Small flies to tackle big questions: assaying complex bacterial virulence mechanisms usingDrosophila melanogaster. Cell Microbiol 2014; 16:824-33. [DOI: 10.1111/cmi.12292] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Revised: 03/05/2014] [Accepted: 03/10/2014] [Indexed: 12/29/2022]
Affiliation(s)
- Marie-Odile Fauvarque
- Univ. Grenoble Alpes; iRTSV-BGE; F-38000 Grenoble France
- CEA; iRTSV-BGE; F-38000 Grenoble France
- INSERM; BGE; F-38000 Grenoble France
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25
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Fredlund J, Enninga J. Cytoplasmic access by intracellular bacterial pathogens. Trends Microbiol 2014; 22:128-37. [PMID: 24530174 DOI: 10.1016/j.tim.2014.01.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 01/08/2014] [Accepted: 01/10/2014] [Indexed: 02/08/2023]
Abstract
Entry into host cells is a strategy widely used by bacterial pathogens, after which they either remain within membrane-bound compartments or rupture the endocytic vacuole to reach the cytoplasm. During recent years, cytoplasmic access has been documented for an increasing number of pathogens. Here we review how classical cytoplasmic bacterial pathogens rupture their endocytic vacuoles as well as the mechanisms used to accomplish this task by bacterial species for which host cytoplasmic localization has only recently been identified. We also discuss the consequences for pathogenesis resulting from this change in intracellular localization, with a particular focus on the role of the host. What emerges is that cytoplasmic access plays an important role in the pathophysiology of an increasing number of intracellular bacterial pathogens.
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Affiliation(s)
- Jennifer Fredlund
- Unité 'Dynamique des interactions hôte-pathogène', Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris, France
| | - Jost Enninga
- Unité 'Dynamique des interactions hôte-pathogène', Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris, France.
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26
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Panayidou S, Ioannidou E, Apidianakis Y. Human pathogenic bacteria, fungi, and viruses in Drosophila: disease modeling, lessons, and shortcomings. Virulence 2014; 5:253-69. [PMID: 24398387 DOI: 10.4161/viru.27524] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Drosophila has been the invertebrate model organism of choice for the study of innate immune responses during the past few decades. Many Drosophila-microbe interaction studies have helped to define innate immunity pathways, and significant effort has been made lately to decipher mechanisms of microbial pathogenesis. Here we catalog 68 bacterial, fungal, and viral species studied in flies, 43 of which are relevant to human health. We discuss studies of human pathogens in flies revealing not only the elicitation and avoidance of immune response but also mechanisms of tolerance, host tissue homeostasis, regeneration, and predisposition to cancer. Prominent among those is the emerging pattern of intestinal regeneration as a defense response induced by pathogenic and innocuous bacteria. Immunopathology mechanisms and many microbial virulence factors have been elucidated, but their relevance to human health conventionally necessitates validation in mammalian models of infection.
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Affiliation(s)
- Stavria Panayidou
- Department of Biological Sciences; University of Cyprus; Nicosia, Cyprus
| | - Eleni Ioannidou
- Department of Biological Sciences; University of Cyprus; Nicosia, Cyprus
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Péan CB, Dionne MS. Intracellular infections in Drosophila melanogaster: host defense and mechanisms of pathogenesis. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2014; 42:57-66. [PMID: 23648644 DOI: 10.1016/j.dci.2013.04.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 04/12/2013] [Accepted: 04/19/2013] [Indexed: 06/02/2023]
Abstract
The fruit-fly Drosophila melanogaster has emerged as a powerful model to study innate immunity against intracellular pathogens. To combat infection, the fly relies on multiple lines of defense, many of which are shared with mammals and arthropod vectors of human diseases. In addition to conserved immune pathways, the ease of performing sophisticated genetic screens has allowed the identification of novel host immune factors and novel pathogen virulence factors. Recently, some groups have exploited this to simultaneously analyze the host and pathogen genetics of intracellular infection. This review aims to unravel the Drosophila immune response against intracellular pathogens, highlighting recent discoveries.
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Affiliation(s)
- Claire B Péan
- Centre for Molecular and Cellular Biology of Inflammation and Peter Gorer Department of Immunobiology, King's College London School of Medicine, London SE1 1UL, UK
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Valanne S. Functional genomic analysis of the Drosophila immune response. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2014; 42:93-101. [PMID: 23707784 DOI: 10.1016/j.dci.2013.05.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 05/13/2013] [Accepted: 05/13/2013] [Indexed: 06/02/2023]
Abstract
Drosophila melanogaster has been widely used as a model organism for over a century now, and also as an immunological research model for over 20 years. With the emergence of RNA interference (RNAi) in Drosophila as a robust tool to silence genes of interest, large-scale or genome-wide functional analysis has become a popular way of studying the Drosophila immune response in cell culture. Drosophila immunity is composed of cellular and humoral immunity mechanisms, and especially the systemic, humoral response pathways have been extensively dissected using the functional genomic approach. Although most components of the main immune pathways had already been found using traditional genetic screening techniques, important findings including pathway components, positive and negative regulators and modifiers have been made with RNAi screening. Additionally, RNAi screening has produced new information on host-pathogen interactions related to the pathogenesis of many microbial species.
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Affiliation(s)
- Susanna Valanne
- Institute of Biomedical Technology and BioMediTech, Tampere University, 33520 Tampere, Finland.
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Abstract
A wide spectrum of pathogenic bacteria and protozoa has adapted to an intracellular life-style, which presents several advantages, including accessibility to host cell metabolites and protection from the host immune system. Intracellular pathogens have developed strategies to enter and exit their host cells while optimizing survival and replication, progression through the life cycle, and transmission. Over the last decades, research has focused primarily on entry, while the exit process has suffered from neglect. However, pathogen exit is of fundamental importance because of its intimate association with dissemination, transmission, and inflammation. Hence, to fully understand virulence mechanisms of intracellular pathogens at cellular and systemic levels, it is essential to consider exit mechanisms to be a key step in infection. Exit from the host cell was initially viewed as a passive process, driven mainly by physical stress as a consequence of the explosive replication of the pathogen. It is now recognized as a complex, strategic process termed "egress," which is just as well orchestrated and temporally defined as entry into the host and relies on a dynamic interplay between host and pathogen factors. This review compares egress strategies of bacteria, pathogenic yeast, and kinetoplastid and apicomplexan parasites. Emphasis is given to recent advances in the biology of egress in mycobacteria and apicomplexans.
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Nanduri B, Suvarnapunya AE, Venkatesan M, Edelmann MJ. Deubiquitinating enzymes as promising drug targets for infectious diseases. Curr Pharm Des 2013; 19:3234-47. [PMID: 23151130 DOI: 10.2174/1381612811319180008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 11/01/2012] [Indexed: 01/25/2023]
Abstract
Deubiquitinating enzymes (DUBs) remove ubiquitin and ubiquitin-like modifications from proteins and they have been known to contribute to processes relevant in microbial infection, such as immune responses pathways. Numerous viral and bacterial DUBs have been identified, and activities of several host DUBs are known to be modulated during the infection process, either by a pathogen or by a host. Recently there have been attempts to take advantage of this feature and design therapeutic inhibitors of DUBs that can be used to limit the spread of infection. This review is focused on exploring the potential of DUBs in the treatment of infectious diseases.
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Affiliation(s)
- Bindu Nanduri
- Institute for Genomics, Biocomputing and Biotechnology, Mississippi State University, Mississippi State, MS 39762, USA
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IglE is an outer membrane-associated lipoprotein essential for intracellular survival and murine virulence of type A Francisella tularensis. Infect Immun 2013; 81:4026-40. [PMID: 23959721 DOI: 10.1128/iai.00595-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
IglE is a small, hypothetical protein encoded by the duplicated Francisella pathogenicity island (FPI). Inactivation of both copies of iglE rendered Francisella tularensis subsp. tularensis Schu S4 avirulent and incapable of intracellular replication, owing to an inability to escape the phagosome. This defect was fully reversed following single-copy expression of iglE in trans from attTn7 under the control of the Francisella rpsL promoter, thereby establishing that the loss of iglE, and not polar effects on downstream vgrG gene expression, was responsible for the defect. IglE is exported to the Francisella outer membrane as an ∼13.9-kDa lipoprotein, determined on the basis of a combination of selective Triton X-114 solubilization, radiolabeling with [(3)H]palmitic acid, and sucrose density gradient membrane partitioning studies. Lastly, a genetic screen using the iglE-null live vaccine strain resulted in the identification of key regions in the carboxyl terminus of IglE that are required for intracellular replication of Francisella tularensis in J774A.1 macrophages. Thus, IglE is essential for Francisella tularensis virulence. Our data support a model that likely includes protein-protein interactions at or near the bacterial cell surface that are unknown at present.
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A phenotype at last: essential role for the Yersinia enterocolitica Ysa type III secretion system in a Drosophila melanogaster S2 cell model. Infect Immun 2013; 81:2478-87. [PMID: 23630961 DOI: 10.1128/iai.01454-12] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The highly pathogenic Yersinia enterocolitica strains have a chromosomally encoded type III secretion system (T3SS) that is expressed and functional in vitro only when the bacteria are cultured at 26 °C. Mutations that render this system nonfunctional are slightly attenuated in the mouse model of infection only following an oral inoculation and only at early time points postinfection. The discrepancy between the temperature required for the Ysa gene expression and the physiological temperature required for mammalian model systems has made defining the role of this T3SS challenging. Therefore, we explored the use of Drosophila S2 cells as a model system for studying Ysa function. We show here that Y. enterocolitica is capable of infecting S2 cells and replicating intracellularly to high levels, an unusual feature of this pathogen. Importantly, we show that the Ysa T3SS is required for robust intracellular replication. A secretion-deficient mutant lacking the secretin gene, ysaC, is defective in replication within S2 cells, marking the first demonstration of a pronounced Ysa-dependent virulence phenotype. Establishment of S2 cells as a model for Y. enterocolitica infection provides a versatile tool to elucidate the role of the Ysa T3SS in the life cycle of this gastrointestinal pathogen.
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Clayton EL, Minogue S, Waugh MG. Mammalian phosphatidylinositol 4-kinases as modulators of membrane trafficking and lipid signaling networks. Prog Lipid Res 2013; 52:294-304. [PMID: 23608234 PMCID: PMC3989048 DOI: 10.1016/j.plipres.2013.04.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 04/08/2013] [Indexed: 12/19/2022]
Abstract
The four mammalian phosphatidylinositol 4-kinases modulate inter-organelle lipid trafficking, phosphoinositide signalling and intracellular vesicle trafficking. In addition to catalytic domains required for the synthesis of PI4P, the phosphatidylinositol 4-kinases also contain isoform-specific structural motifs that mediate interactions with proteins such as AP-3 and the E3 ubiquitin ligase Itch, and such structural differences determine isoform-specific roles in membrane trafficking. Moreover, different permutations of phosphatidylinositol 4-kinase isozymes may be required for a single cellular function such as occurs during distinct stages of GPCR signalling and in Golgi to lysosome trafficking. Phosphatidylinositol 4-kinases have recently been implicated in human disease. Emerging paradigms include increased phosphatidylinositol 4-kinase expression in some cancers, impaired functioning associated with neurological pathologies, the subversion of PI4P trafficking functions in bacterial infection and the activation of lipid kinase activity in viral disease. We discuss how the diverse and sometimes overlapping functions of the phosphatidylinositol 4-kinases present challenges for the design of isoform-specific inhibitors in a therapeutic context.
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Affiliation(s)
- Emma L Clayton
- UCL Institute for Liver & Digestive Health, UCL Royal Free Campus, Rowland Hill Street, London NW3 2PF, United Kingdom
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Celli J, Zahrt TC. Mechanisms of Francisella tularensis intracellular pathogenesis. Cold Spring Harb Perspect Med 2013; 3:a010314. [PMID: 23545572 DOI: 10.1101/cshperspect.a010314] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Francisella tularensis is a zoonotic intracellular pathogen and the causative agent of the debilitating febrile illness tularemia. Although natural infections by F. tularensis are sporadic and generally localized, the low infectious dose, with the ability to be transmitted to humans via multiple routes and the potential to cause life-threatening infections, has led to concerns that this bacterium could be used as an agent of bioterror and released intentionally into the environment. Recent studies of F. tularensis and other closely related Francisella species have greatly increased our understanding of mechanisms used by this organism to infect and cause disease within the host. Here, we review the intracellular life cycle of Francisella and highlight key genetic determinants and/or pathways that contribute to the survival and proliferation of this bacterium within host cells.
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Affiliation(s)
- Jean Celli
- Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MO 59840, USA
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Zhu H, Qian J, Wang W, Yan Q, Xu Y, Jiang Y, Zhang L, Lu F, Hu W, Zhang X, Wang F, Sun X. RNA interference of GADD153 protects photoreceptors from endoplasmic reticulum stress-mediated apoptosis after retinal detachment. PLoS One 2013; 8:e59339. [PMID: 23555658 PMCID: PMC3612068 DOI: 10.1371/journal.pone.0059339] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 02/13/2013] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Apoptosis of photoreceptors plays a critical role in the vision loss caused by retinal detachment (RD). Pharmacologic inhibition of photoreceptor cell death may prevent RD. This study investigated the role of GADD153 that participates in endoplasmic reticulum (ER) stress-mediated apoptosis of photoreceptor cells after RD. METHODS Retinal detachment was created in Wistar rats by subretinal injection of hyaluronic acid. The rats were then randomly divided into four groups: normal control group, RD group, GADD153 RNAi group and vehicle group. RNA interference of GADD153 was performed using short hairpin RNA (shRNA). Expressions of GADD153 mRNA and protein were examined by RT-PCR and Western blotting analysis, respectively. GADD153 protein distribution in the retinal cells was observed using immunofluorescence confocal laser scanning microscopy. Apoptosis of retinal cells was determined by TdT-mediated fluorescein-16-dUTP nick-end labeling (TUNEL) assay. RESULTS Lentivirus GADD153 shRNA with the most effective silencing effect was chosen for in vivo animal study and was successfully delivered into the retinal tissues. GADD153 mRNA and protein expressions in GADD153 RNAi group were significantly lower than those in the RD group. Silencing of GADD153 by RNAi protected photoreceptors from ER stress-induced apoptosis. CONCLUSION ER stress-mediated pathway is involved in photoreceptor cell apoptosis after RD. GADD153 is a key regulatory molecule regulating ER-stress pathways and plays a crucial role in the apoptosis of photoreceptor cells after RD.
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Affiliation(s)
- Hong Zhu
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
- Department of Ophthalmology, No.3 People’s Hospital Affiliated to Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Jin Qian
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Wenqiu Wang
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Quan Yan
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Ying Xu
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Yuan Jiang
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Lei Zhang
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Fengqing Lu
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Weiting Hu
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Xi Zhang
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
- Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Fenghua Wang
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
- Shanghai Key Laboratory of Fundus Disease, Shanghai, China
- * E-mail: (XS); (FW)
| | - Xiaodong Sun
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
- Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
- * E-mail: (XS); (FW)
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Bradburne CE, Verhoeven AB, Manyam GC, Chaudhry SA, Chang EL, Thach DC, Bailey CL, van Hoek ML. Temporal transcriptional response during infection of type II alveolar epithelial cells with Francisella tularensis live vaccine strain (LVS) supports a general host suppression and bacterial uptake by macropinocytosis. J Biol Chem 2013; 288:10780-91. [PMID: 23322778 DOI: 10.1074/jbc.m112.362178] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Pneumonic tularemia is caused by inhalation of Francisella tularensis, one of the most infectious microbes known. We wanted to study the kinetics of the initial and early interactions between bacterium and host cells in the lung. To do this, we examined the infection of A549 airway epithelial cells with the live vaccine strain (LVS) of F. tularensis. A549 cells were infected and analyzed for global transcriptional response at multiple time points up to 16 h following infection. At 15 min and 2 h, a strong transcriptional response was observed including cytoskeletal rearrangement, intracellular transport, and interferon signaling. However, at later time points (6 and 16 h), very little differential gene expression was observed, indicating a general suppression of the host response consistent with other reported cell lines and murine tissues. Genes for macropinocytosis and actin/cytoskeleton rearrangement were highly up-regulated and common to the 15 min and 2 h time points, suggesting the use of this method for bacterial entry into cells. We demonstrate macropinocytosis through the uptake of FITC-dextran and amiloride inhibition of Francisella LVS uptake. Our results suggest that macropinocytosis is a potential mechanism of intracellular entry by LVS and that the host cell response is suppressed during the first 2-6 h of infection. These results suggest that the attenuated Francisella LVS induces significant host cell signaling at very early time points after the bacteria's interaction with the cell.
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Affiliation(s)
- Christopher E Bradburne
- Center for Bio/Molecular Science and Engineering, United States Naval Research Laboratory, Washington, DC 20375, USA
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37
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De Jesús DA, O’Connor TJ, Isberg RR. Analysis of Legionella infection using RNAi in Drosophila cells. Methods Mol Biol 2013; 954:251-64. [PMID: 23150401 PMCID: PMC4075055 DOI: 10.1007/978-1-62703-161-5_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
RNA interference (RNAi) is the process of specific gene silencing by the use of double-stranded RNA (dsRNA). In cultured Drosophila cells, RNAi methodologies are well established and easily executed: dsRNA, when added to the cell culture medium, is efficiently internalized by the cells and, through the activity of endogenous processing machinery, targets the specified mRNA for degradation resulting in reduced levels of its encoded protein. This technique has proven very useful in studying the role of host genes during Legionella pneumophila infections, as it allows the effect of host factor depletion on intracellular growth of the bacterium to be examined. In this chapter we present the methods commonly used in our laboratory to study intracellular growth of L. pneumophila using dsRNA in Drosophila cells.
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Affiliation(s)
- Dennise A. De Jesús
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111
| | - Tamara J. O’Connor
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111
| | - Ralph R. Isberg
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111,Corresponding author: Ralph R. Isberg, Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111,
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Evaluation of phosphatidylinositol-4-kinase IIIα as a hepatitis C virus drug target. J Virol 2012; 86:11595-607. [PMID: 22896614 DOI: 10.1128/jvi.01320-12] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Phosphatidylinositol-4-kinase IIIα (PI4KIIIα) is an essential host cell factor for hepatitis C virus (HCV) replication. An N-terminally truncated 130-kDa form was used to reconstitute an in vitro biochemical lipid kinase assay that was optimized for small-molecule compound screening and identified potent and specific inhibitors. Cell culture studies with PI4KIIIα inhibitors demonstrated that the kinase activity was essential for HCV RNA replication. Two PI4KIIIα inhibitors were used to select cell lines harboring HCV replicon mutants with a 20-fold loss in sensitivity to the compounds. Reverse genetic mapping isolated an NS4B-NS5A segment that rescued HCV RNA replication in PIK4IIIα-deficient cells. HCV RNA replication occurs on specialized membranous webs, and this study with PIK4IIIα inhibitor-resistant mutants provides a genetic link between NS4B/NS5A functions and PI4-phosphate lipid metabolism. A comprehensive assessment of PI4KIIIα as a drug target included its evaluation for pharmacologic intervention in vivo through conditional transgenic murine lines that mimic target-specific inhibition in adult mice. Homozygotes that induce a knockout of the kinase domain or knock in a single amino acid substitution, kinase-defective PI4KIIIα, displayed a lethal phenotype with a fairly widespread mucosal epithelial degeneration of the gastrointestinal tract. This essential host physiologic role raises doubt about the pursuit of PI4KIIIα inhibitors for treatment of chronic HCV infection.
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Chong A, Wehrly TD, Child R, Hansen B, Hwang S, Virgin HW, Celli J. Cytosolic clearance of replication-deficient mutants reveals Francisella tularensis interactions with the autophagic pathway. Autophagy 2012; 8:1342-56. [PMID: 22863802 DOI: 10.4161/auto.20808] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Cytosolic bacterial pathogens must evade intracellular innate immune recognition and clearance systems such as autophagy to ensure their survival and proliferation. The intracellular cycle of the bacterium Francisella tularensis is characterized by rapid phagosomal escape followed by extensive proliferation in the macrophage cytoplasm. Cytosolic replication, but not phagosomal escape, requires the locus FTT0369c, which encodes the dipA gene (deficient in intracellular replication A). Here, we show that a replication-deficient, ∆dipA mutant of the prototypical SchuS4 strain is eventually captured from the cytosol of murine and human macrophages into double-membrane vacuoles displaying the late endosomal marker, LAMP1, and the autophagy-associated protein, LC3, coinciding with a reduction in viable intracellular bacteria. Capture of SchuS4ΔdipA was not dipA-specific as other replication-deficient bacteria, such as chloramphenicol-treated SchuS4 and a purine auxotroph mutant SchuS4ΔpurMCD, were similarly targeted to autophagic vacuoles. Vacuoles containing replication-deficient bacteria were labeled with ubiquitin and the autophagy receptors SQSTM1/p62 and NBR1, and their formation was decreased in macrophages from either ATG5-, LC3B- or SQSTM1-deficient mice, indicating recognition by the ubiquitin-SQSTM1-LC3 pathway. While a fraction of both the wild-type and the replication-impaired strains were ubiquitinated and recruited SQSTM1, only the replication-defective strains progressed to autophagic capture, suggesting that wild-type Francisella interferes with the autophagic cascade. Survival of replication-deficient strains was not restored in autophagy-deficient macrophages, as these bacteria died in the cytosol prior to autophagic capture. Collectively, our results demonstrate that replication-impaired strains of Francisella are cleared by autophagy, while replication-competent bacteria seem to interfere with autophagic recognition, therefore ensuring survival and proliferation.
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Affiliation(s)
- Audrey Chong
- Tularemia Pathogenesis Section, Laboratory of Intracellular Parasites, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
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Pohanka M, Pavlis O, Ruttkay-Nedecky B, Sochor J, Sobotka J, Pikula J, Adam V, Kizek R. Tularemia progression accompanied with oxidative stress and antioxidant alteration in spleen and liver of BALB/c mice. J Microbiol 2012; 50:401-8. [PMID: 22752903 DOI: 10.1007/s12275-012-1621-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 01/17/2012] [Indexed: 10/28/2022]
Abstract
Francisella tularensis is the causative agent of tularemia. It is an intracellular pathogen with the ability to survive within phagosomes and induce pyroptotic cell death. In this study, we attempted to prove whether oxidative imbalance plays a significant role in tularemia pathogenesis. In our experimental model, we subcutaneously infected female BALB/c mice (dose 10(5) CFU of F. tularensis LVS). Liver, spleen, and blood were collected from mice at regular intervals from days 1-15 after infection. The bacterial burden was assessed by a cultivation test. The burden was unchanging from the 2(nd) to 6(th) day after infection. The bacterial burden corresponded to the plasmatic level of IFN-γ, IL-6, and liver malondialdehyde. After the phase of acute bacteraemia and the innate immunity reaction, the levels of reduced glutathione and total low molecular weight antioxidants decreased significantly and the activity of caspase-3 increased in the liver. The level of reduced glutathione decreased to 25% of the original level, and the total level of low molecular weight antioxidants was less than 50% of the initial amount. The demonstrated effects of tularemia-induced pathology had a more extensive impact on the liver than on the spleen.
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Affiliation(s)
- Miroslav Pohanka
- Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 500 01, Hradec Kralove, Czech Republic.
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Abstract
The deleterious and sometimes fatal outcomes of bacterial infectious diseases are the net result of the interactions between the pathogen and the host, and the genetically tractable fruit fly, Drosophila melanogaster, has emerged as a valuable tool for modeling the pathogen-host interactions of a wide variety of bacteria. These studies have revealed that there is a remarkable conservation of bacterial pathogenesis and host defence mechanisms between higher host organisms and Drosophila. This review presents an in-depth discussion of the Drosophila immune response, the Drosophila killing model, and the use of the model to examine bacterial-host interactions. The recent introduction of the Drosophila model into the oral microbiology field is discussed, specifically the use of the model to examine Porphyromonas gingivalis-host interactions, and finally the potential uses of this powerful model system to further elucidate oral bacterial-host interactions are addressed.
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Affiliation(s)
- Christina O Igboin
- Division of Oral Biology, College of Dentistry, The Ohio State University, Columbus, Ohio, USA
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42
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Cureton DK, Burdeinick-Kerr R, Whelan SPJ. Genetic inactivation of COPI coatomer separately inhibits vesicular stomatitis virus entry and gene expression. J Virol 2012; 86:655-66. [PMID: 22072764 PMCID: PMC3255828 DOI: 10.1128/jvi.05810-11] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 10/26/2011] [Indexed: 11/20/2022] Open
Abstract
Viruses coopt cellular membrane transport to invade cells, establish intracellular sites of replication, and release progeny virions. Recent genome-wide RNA interference (RNAi) screens revealed that genetically divergent viruses require biosynthetic membrane transport by the COPI coatomer complex for efficient replication. Here we found that disrupting COPI function by RNAi inhibited an early stage of vesicular stomatitis virus (VSV) replication. To dissect which replication stage(s) was affected by coatomer inactivation, we used visual and biochemical assays to independently measure the efficiency of viral entry and gene expression in hamster (ldlF) cells depleted of the temperature-sensitive ε-COP subunit. We show that ε-COP depletion for 12 h caused a primary block to virus internalization and a secondary defect in viral gene expression. Using brefeldin A (BFA), a chemical inhibitor of COPI function, we demonstrate that short-term (1-h) BFA treatments inhibit VSV gene expression, while only long-term (12-h) treatments block virus entry. We conclude that prolonged coatomer inactivation perturbs cellular endocytic transport and thereby indirectly impairs VSV entry. Our results offer an explanation of why COPI coatomer is frequently identified in screens for cellular factors that support cell invasion by microbial pathogens.
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Affiliation(s)
- David K Cureton
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA.
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Serbus LR, Ferreccio A, Zhukova M, McMorris CL, Kiseleva E, Sullivan W. A feedback loop between Wolbachia and the Drosophila gurken mRNP complex influences Wolbachia titer. J Cell Sci 2011; 124:4299-308. [PMID: 22193955 DOI: 10.1242/jcs.092510] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Although much is known about interactions between bacterial endosymbionts and their hosts, little is known concerning the host factors that influence endosymbiont titer. Wolbachia endosymbionts are globally dispersed throughout most insect species and are the causative agent in filarial nematode-mediated disease. Our investigation indicates that gurken (grk), a host gene encoding a crucial axis determinant, has a cumulative, dosage-sensitive impact on Wolbachia growth and proliferation during Drosophila oogenesis. This effect appears to be mediated by grk mRNA and its protein-binding partners Squid and Hrp48/Hrb27C, implicating the grk mRNA-protein (mRNP) complex as a rate-limiting host factor controlling Wolbachia titer. Furthermore, highly infected flies exhibit defects that match those occurring with disruption of grk mRNPs, such as nurse cell chromatin disruptions and malformation of chorionic appendages. These findings suggest a feedback loop in which Wolbachia interaction with the grk mRNP affects both Wolbachia titer and grk mRNP function.
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Affiliation(s)
- Laura R Serbus
- MCD Biology, University of California, 1156 High St, Santa Cruz, CA 95064, USA.
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Ligeon LA, Temime-Smaali N, Lafont F. Ubiquitylation and autophagy in the control of bacterial infections and related inflammatory responses. Cell Microbiol 2011; 13:1303-11. [PMID: 21740497 DOI: 10.1111/j.1462-5822.2011.01628.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The ubiquitin proteasome system and autophagy constitute key signalling pathways in the host response to infection. The identification of adaptors linking the two pathways has prompted a re-examination of the latter's involvement in inflammatory reactions and the clearance of bacteria. The ubiquitin-autophagy pathway is a preferred target for effectors from pathogens that seek to exploit and evade the host defence mechanisms. A number of new players and signalling nodes have recently been identified. Here, we discuss these new insights into the host's control of bacterial infection.
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Affiliation(s)
- Laure-Anne Ligeon
- Cellular Microbiology of Infectious Pathogens, Lille Center for Infection and Immunity, CNRS UMR8204, INSERM U1019, University of Lille Nord-de-France, Institut Pasteur de Lille, F-59019 Lille, France
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Al-Khodor S, Abu Kwaik Y. Triggering Ras signalling by intracellular Francisella tularensis through recruitment of PKCα and βI to the SOS2/GrB2 complex is essential for bacterial proliferation in the cytosol. Cell Microbiol 2011; 12:1604-21. [PMID: 20618341 DOI: 10.1111/j.1462-5822.2010.01494.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Intracellular proliferation of Francisella tularensis is essential for manifestation of the fatal disease tularaemia, and is classified as a category A bioterrorism agent. The F. tularensis-containing phagosome (FCP) matures into a late endosome-like phagosome with limited fusion to lysosomes, followed by rapid bacterial escape into the cytosol. The Francisella pathogenicity island (FPI) encodes a type VI-like secretion system, and the FPI-encoded IglC is essential for evasion of lysosomal fusion and phagosomal escape. Many host signalling events are likely to be modulated by F. tularensis to render the cell permissive for intracellular proliferation but they are not fully understood. Here we show that within 15 min of infection, intracellular F. tularensis ssp. novicida triggers IglC-dependent temporal activation of Ras, but attached extracellular bacteria fail to trigger Ras activation, which has never been shown for other intracellular pathogens. Intracellular F. tularensis ssp. novicida triggers activation of Ras through recruitment of PKCα and PKCβI to the SOS2/GrB2 complex. Silencing of SOS2, GrB2 and PKCα and PKCβI by RNAi has no effect on evasion of lysosomal fusion and bacterial escape into the cytosol but renders the cytosol non-permissive for replication of F. tularensis ssp. novicida. Since Ras activation promotes cell survival, we show that silencing of SOS2, GrB2 and PKCα and βI is associated with rapid early activation of caspase-3 within 8 h post infection. However, silencing of SOS2, GrB2 and PKCα and βI does not affect phosphorylation of Akt or Erk, indicating that activation of the PI3K/Akt and the Erk signalling cascade are independent of the F. tularensis-triggered Ras activation. We conclude that intracellular F. tularensis ssp. novicida triggers temporal and early activation of Ras through the SOS2/GrB2/PKCα/PKCβI quaternary complex. Temporal and rapid trigger of Ras signalling by intracellular F. tularensis is essential for intracellular bacterial proliferation within the cytosol, and this is associated with downregulation of early caspase-3 activation.
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Affiliation(s)
- Souhaila Al-Khodor
- Department of Microbiology and Immunology, College of Medicine, Department of Biology, University of Louisville, Louisville, KY 40202, USA
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Jiang M, Instrell R, Saunders B, Berven H, Howell M. Tales from an academic RNAi screening facility; FAQs. Brief Funct Genomics 2011; 10:227-37. [PMID: 21527443 DOI: 10.1093/bfgp/elr016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
RNAi technology is now a well-established and widely employed research technique that has been adopted by many researchers for use in large-scale screening campaigns. Here, we offer our experience of genome-wide siRNA screening from the perspective of a facility providing screening as a service to a wide range of researchers with diverse interests and approaches. We have experienced the emotional rollercoaster of screening from the exuberant early promise of a screen, the messy reality of the data through to the recognition of screen data as a potential information goldmine. Here, we use some of the questions we most frequently encounter to highlight the initial concerns of many researchers embarking on a siRNA screen and conclude that an informed view of what can be reasonably expected from a screen is essential to the most effective implementation of the technology. Along the way, we suggest that for this area of research at least, either centralization of the resources or close and open collaboration between interested parties offers distinct advantages.
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Affiliation(s)
- Ming Jiang
- High-Throughput Screening facility, Cancer Research UK, London Research Institute
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Akimana C, Kwaik YA. Francisella-arthropod vector interaction and its role in patho-adaptation to infect mammals. Front Microbiol 2011; 2:34. [PMID: 21687425 PMCID: PMC3109307 DOI: 10.3389/fmicb.2011.00034] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2010] [Accepted: 02/07/2011] [Indexed: 11/13/2022] Open
Abstract
Francisella tularensis is a Gram-negative, intracellular, zoonotic bacterium, and is the causative agent of tularemia with a broad host range. Arthropods such as ticks, mosquitoes, and flies maintain F. tularensis in nature by transmitting the bacteria among small mammals. While the tick is largely believed to be a biological vector of F. tularensis, transmission by mosquitoes and flies is largely believed to be mechanical on the mouthpart through interrupted feedings. However, the mechanism of infection of the vectors by F. tularensis is not well understood. Since F. tularensis has not been localized in the salivary gland of the primary human biting ticks, it is thought that bacterial transmission by ticks is through mechanical inoculation of tick feces containing F. tularensis into the skin wound. Drosophila melanogaster is an established good arthropod model for arthropod vectors of tularemia, where F. tularensis infects hemocytes, and is found in hemolymph, as seen in ticks. In addition, phagosome biogenesis and robust intracellular proliferation of F. tularensis in arthropod-derived cells are similar to that in mammalian macrophages. Furthermore, bacterial factors required for infectivity of mammals are often required for infectivity of the fly by F. tularensis. Several host factors that contribute to F. tularensis intracellular pathogenesis in D. melanogaster have been identified, and F. tularensis targets some of the evolutionarily conserved eukaryotic processes to enable intracellular survival and proliferation in evolutionarily distant hosts.
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Affiliation(s)
- Christine Akimana
- Department of Microbiology and Immunology, College of Medicine, University of Louisville Louisville, KY, USA
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Booker M, Samsonova AA, Kwon Y, Flockhart I, Mohr SE, Perrimon N. False negative rates in Drosophila cell-based RNAi screens: a case study. BMC Genomics 2011; 12:50. [PMID: 21251254 PMCID: PMC3036618 DOI: 10.1186/1471-2164-12-50] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 01/20/2011] [Indexed: 01/13/2023] Open
Abstract
Background High-throughput screening using RNAi is a powerful gene discovery method but is often complicated by false positive and false negative results. Whereas false positive results associated with RNAi reagents has been a matter of extensive study, the issue of false negatives has received less attention. Results We performed a meta-analysis of several genome-wide, cell-based Drosophila RNAi screens, together with a more focused RNAi screen, and conclude that the rate of false negative results is at least 8%. Further, we demonstrate how knowledge of the cell transcriptome can be used to resolve ambiguous results and how the number of false negative results can be reduced by using multiple, independently-tested RNAi reagents per gene. Conclusions RNAi reagents that target the same gene do not always yield consistent results due to false positives and weak or ineffective reagents. False positive results can be partially minimized by filtering with transcriptome data. RNAi libraries with multiple reagents per gene also reduce false positive and false negative outcomes when inconsistent results are disambiguated carefully.
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Affiliation(s)
- Matthew Booker
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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Asare R, Kwaik YA. Exploitation of host cell biology and evasion of immunity by francisella tularensis. Front Microbiol 2011; 1:145. [PMID: 21687747 PMCID: PMC3109322 DOI: 10.3389/fmicb.2010.00145] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 12/21/2010] [Indexed: 12/13/2022] Open
Abstract
Francisella tularensis is an intracellular bacterium that infects humans and many small mammals. During infection, F. tularensis replicates predominantly in macrophages but also proliferate in other cell types. Entry into host cells is mediate by various receptors. Complement-opsonized F. tularensis enters into macrophages by looping phagocytosis. Uptake is mediated in part by Syk, which may activate actin rearrangement in the phagocytic cup resulting in the engulfment of F. tularensis in a lipid raft rich phagosome. Inside the host cells, F. tularensis resides transiently in an acidified late endosome-like compartment before disruption of the phagosomal membrane and escape into the cytosol, where bacterial proliferation occurs. Modulation of phagosome biogenesis and escape into the cytosol is mediated by the Francisella pathogenicity island-encoded type VI-like secretion system. Whilst inside the phagosome, F. tularensis temporarily induce proinflammatory cytokines in PI3K/Akt-dependent manner, which is counteracted by the induction of SHIP that negatively regulates PI3K/Akt activation and promotes bacterial escape into the cytosol. Interestingly, F. tularensis subverts CD4 T cells-mediated killing by inhibiting antigen presentation by activated macrophages through ubiquitin-dependent degradation of MHC II molecules on activated macrophages. In the cytosol, F. tularensis is recognized by the host cell inflammasome, which is down-regulated by F. tularensis that also inhibits caspase-1 and ASC activity. During late stages of intracellular proliferation, caspase-3 is activated but apoptosis is delayed through activation of NF-κB and Ras, which ensures cell viability.
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Affiliation(s)
- Rexford Asare
- Department of Microbiology and Immunology, School of Medicine, University of Louisville Louisville, KY, USA
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Chong A, Celli J. The francisella intracellular life cycle: toward molecular mechanisms of intracellular survival and proliferation. Front Microbiol 2010; 1:138. [PMID: 21687806 PMCID: PMC3109316 DOI: 10.3389/fmicb.2010.00138] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Accepted: 12/05/2010] [Indexed: 11/13/2022] Open
Abstract
The tularemia-causing bacterium Francisella tularensis is a facultative intracellular organism with a complex intracellular lifecycle that ensures its survival and proliferation in a variety of mammalian cell types, including professional phagocytes. Because this cycle is essential to Francisella pathogenesis and virulence, much research has focused on deciphering the mechanisms of its intracellular survival and replication and characterizing both bacterial and host determinants of the bacterium's intracellular cycle. Studies of various strains and host cell models have led to the consensual paradigm of Francisella as a cytosolic pathogen, but also to some controversy about its intracellular cycle. In this review, we will detail major findings that have advanced our knowledge of Francisella intracellular survival strategies and also attempt to reconcile discrepancies that exist in our molecular understanding of the Francisella–phagocyte interactions.
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Affiliation(s)
- Audrey Chong
- Tularemia Pathogenesis Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health Hamilton, MT, USA
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