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Heron R, Amato C, Wood W, Davidson AJ. Understanding the diversity and dynamics of in vivo efferocytosis: Insights from the fly embryo. Immunol Rev 2023; 319:27-44. [PMID: 37589239 PMCID: PMC10952863 DOI: 10.1111/imr.13266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 07/18/2023] [Indexed: 08/18/2023]
Abstract
The clearance of dead and dying cells, termed efferocytosis, is a rapid and efficient process and one that is critical for organismal health. The extraordinary speed and efficiency with which dead cells are detected and engulfed by immune cells within tissues presents a challenge to researchers who wish to unravel this fascinating process, since these fleeting moments of uptake are almost impossible to catch in vivo. In recent years, the fruit fly (Drosophila melanogaster) embryo has emerged as a powerful model to circumvent this problem. With its abundance of dying cells, specialist phagocytes and relative ease of live imaging, the humble fly embryo provides a unique opportunity to catch and study the moment of cell engulfment in real-time within a living animal. In this review, we explore the recent advances that have come from studies in the fly, and how live imaging and genetics have revealed a previously unappreciated level of diversity in the efferocytic program. A variety of efferocytic strategies across the phagocytic cell population ensure efficient and rapid clearance of corpses wherever death is encountered within the varied and complex setting of a multicellular living organism.
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Affiliation(s)
- Rosalind Heron
- Institute for Regeneration and RepairUniversity of EdinburghEdinburghUK
| | - Clelia Amato
- Institute for Regeneration and RepairUniversity of EdinburghEdinburghUK
| | - Will Wood
- Institute for Regeneration and RepairUniversity of EdinburghEdinburghUK
| | - Andrew J. Davidson
- Institute for Regeneration and RepairUniversity of EdinburghEdinburghUK
- School of Cancer SciencesWolfson Wohl Cancer Research Centre, University of GlasgowGlasgowUK
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2
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Touré H, Galindo LA, Lagune M, Glatigny S, Waterhouse RM, Guénal I, Herrmann JL, Girard-Misguich F, Szuplewski S. Mycobacterium abscessus resists the innate cellular response by surviving cell lysis of infected phagocytes. PLoS Pathog 2023; 19:e1011257. [PMID: 36972320 PMCID: PMC10079227 DOI: 10.1371/journal.ppat.1011257] [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: 11/04/2022] [Revised: 04/06/2023] [Accepted: 02/28/2023] [Indexed: 03/29/2023] Open
Abstract
Mycobacterium abscessus is the most pathogenic species among the predominantly saprophytic fast-growing mycobacteria. This opportunistic human pathogen causes severe infections that are difficult to eradicate. Its ability to survive within the host was described mainly with the rough (R) form of M. abscessus, which is lethal in several animal models. This R form is not present at the very beginning of the disease but appears during the progression and the exacerbation of the mycobacterial infection, by transition from a smooth (S) form. However, we do not know how the S form of M. abscessus colonizes and infects the host to then multiply and cause the disease. In this work, we were able to show the hypersensitivity of fruit flies, Drosophila melanogaster, to intrathoracic infections by the S and R forms of M. abscessus. This allowed us to unravel how the S form resists the innate immune response developed by the fly, both the antimicrobial peptides- and cellular-dependent immune responses. We demonstrate that intracellular M. abscessus was not killed within the infected phagocytic cells, by resisting lysis and caspase-dependent apoptotic cell death of Drosophila infected phagocytes. In mice, in a similar manner, intra-macrophage M. abscessus was not killed when M. abscessus-infected macrophages were lysed by autologous natural killer cells. These results demonstrate the propensity of the S form of M. abscessus to resist the host’s innate responses to colonize and multiply within the host.
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Affiliation(s)
- Hamadoun Touré
- Université Paris-Saclay, UVSQ, INSERM, Infection et Inflammation, Montigny-Le-Bretonneux, France
| | - Lee Ann Galindo
- Université Paris-Saclay, UVSQ, INSERM, Infection et Inflammation, Montigny-Le-Bretonneux, France
| | - Marion Lagune
- Université Paris-Saclay, UVSQ, INSERM, Infection et Inflammation, Montigny-Le-Bretonneux, France
| | - Simon Glatigny
- Université Paris-Saclay, UVSQ, INSERM, Infection et Inflammation, Montigny-Le-Bretonneux, France
| | - Robert M. Waterhouse
- Department of Ecology and Evolution, University of Lausanne, and the Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | | | - Jean-Louis Herrmann
- Université Paris-Saclay, UVSQ, INSERM, Infection et Inflammation, Montigny-Le-Bretonneux, France
- Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Ile-de-France Ouest, GHU Paris-Saclay, Hôpital Raymond Poincaré, Garches, France
| | - Fabienne Girard-Misguich
- Université Paris-Saclay, UVSQ, INSERM, Infection et Inflammation, Montigny-Le-Bretonneux, France
- * E-mail: (FGM); (SS)
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3
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Zoncu R, Perera RM. Built to last: lysosome remodeling and repair in health and disease. Trends Cell Biol 2022; 32:597-610. [DOI: 10.1016/j.tcb.2021.12.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/29/2021] [Accepted: 12/30/2021] [Indexed: 12/21/2022]
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4
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Ragland SA, Kagan JC. Cytosolic detection of phagosomal bacteria-Mechanisms underlying PAMP exodus from the phagosome into the cytosol. Mol Microbiol 2021; 116:1420-1432. [PMID: 34738270 DOI: 10.1111/mmi.14841] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 10/29/2021] [Indexed: 12/15/2022]
Abstract
The metazoan innate immune system senses bacterial infections by detecting highly conserved bacterial molecules, termed pathogen-associated molecular patterns (PAMPs). PAMPs are detected by a variety of host pattern recognition receptors (PRRs), whose function is to coordinate downstream immune responses. PRR activities are, in part, regulated by their subcellular localizations. Accordingly, professional phagocytes can detect extracellular bacteria and their PAMPs via plasma membrane-oriented PRRs. Conversely, phagocytosed bacteria and their PAMPs are detected by transmembrane PRRs oriented toward the phagosomal lumen. Even though PAMPs are unable to passively diffuse across membranes, phagocytosed bacteria are also detected by PRRs localized within the host cell cytosol. This phenomenon is explained by phagocytosis of bacteria that specialize in phagosomal escape and cytosolic residence. Contrary to this cytosolic lifestyle, most bacteria studied to date spend their entire intracellular lifestyle contained within phagosomes, yet they also stimulate cytosolic PRRs. Herein, we will review our current understanding of how phagosomal PAMPs become accessible to cytosolic PRRs, as well as highlight knowledge gaps that should inspire future investigations.
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Affiliation(s)
- Stephanie A Ragland
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Jonathan C Kagan
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, 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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McCutcheon JP. The Genomics and Cell Biology of Host-Beneficial Intracellular Infections. Annu Rev Cell Dev Biol 2021; 37:115-142. [PMID: 34242059 DOI: 10.1146/annurev-cellbio-120219-024122] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microbes gain access to eukaryotic cells as food for bacteria-grazing protists, for host protection by microbe-killing immune cells, or for microbial benefit when pathogens enter host cells to replicate. But microbes can also gain access to a host cell and become an important-often required-beneficial partner. The oldest beneficial microbial infections are the ancient eukaryotic organelles now called the mitochondrion and plastid. But numerous other host-beneficial intracellular infections occur throughout eukaryotes. Here I review the genomics and cell biology of these interactions with a focus on intracellular bacteria. The genomes of host-beneficial intracellular bacteria have features that span a previously unfilled gap between pathogens and organelles. Host cell adaptations to allow the intracellular persistence of beneficial bacteria are found along with evidence for the microbial manipulation of host cells, but the cellular mechanisms of beneficial bacterial infections are not well understood. Expected final online publication date for the Annual Review of Cell and Developmental Biology, Volume 37 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- John P McCutcheon
- Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, Arizona 85287, USA;
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Environmental RNA interference in two-spotted spider mite, Tetranychus urticae, reveals dsRNA processing requirements for efficient RNAi response. Sci Rep 2020; 10:19126. [PMID: 33154461 PMCID: PMC7644771 DOI: 10.1038/s41598-020-75682-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 10/16/2020] [Indexed: 12/13/2022] Open
Abstract
Comprehensive understanding of pleiotropic roles of RNAi machinery highlighted the conserved chromosomal functions of RNA interference. The consequences of the evolutionary variation in the core RNAi pathway genes are mostly unknown, but may lead to the species-specific functions associated with gene silencing. The two-spotted spider mite, Tetranychus urticae, is a major polyphagous chelicerate pest capable of feeding on over 1100 plant species and developing resistance to pesticides used for its control. A well annotated genome, susceptibility to RNAi and economic importance, make T. urticae an excellent candidate for development of an RNAi protocol that enables high-throughput genetic screens and RNAi-based pest control. Here, we show that the length of the exogenous dsRNA critically determines its processivity and ability to induce RNAi in vivo. A combination of the long dsRNAs and the use of dye to trace the ingestion of dsRNA enabled the identification of genes involved in membrane transport and 26S proteasome degradation as sensitive RNAi targets. Our data demonstrate that environmental RNAi can be an efficient reverse genetics and pest control tool in T. urticae. In addition, the species-specific properties together with the variation in the components of the RNAi machinery make T. urticae a potent experimental system to study the evolution of RNAi pathways.
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8
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Bohannon KP, Hanson PI. ESCRT puts its thumb on the nanoscale: Fixing tiny holes in endolysosomes. Curr Opin Cell Biol 2020; 65:122-130. [PMID: 32731154 PMCID: PMC7578027 DOI: 10.1016/j.ceb.2020.06.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 06/02/2020] [Accepted: 06/12/2020] [Indexed: 12/22/2022]
Abstract
The ESCRT (endosomal complex required for transport) machinery remodels membranes to bud vesicles away from the cytoplasm. In addition to this classic role, ESCRTs are now understood to repair damage in the plasma membrane, nuclear envelope, and throughout the endolysosomal network. Wounds in endolysosomal membranes are caused by pathogens, particulates, and other chemical or metabolic stresses. Nanoscale damage in these membranes promotes activation and engagement of ESCRT proteins. A full understanding of damage signals, molecular sensing, and the mechanism of membrane repair is yet to be developed. Nevertheless, a triggering role for calcium and ESCRT-I in recruiting ESCRT-III machinery for membrane remodeling is a repeated theme in functional studies of this response. In our current understanding of the continuum of cellular responses to lipid bilayer damage, the ESCRT machinery is fast, sensitive, and deployed independently of other systems.
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Affiliation(s)
- Kevin P Bohannon
- Department of Biological Chemistry, University of Michigan School of Medicine, 1150 W. Medical Center Drive, Ann Arbor, MI, 48109, USA.
| | - Phyllis I Hanson
- Department of Biological Chemistry, University of Michigan School of Medicine, 1150 W. Medical Center Drive, Ann Arbor, MI, 48109, USA.
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9
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Host-Targeted Therapeutics against Multidrug Resistant Intracellular Staphylococcus aureus. Antibiotics (Basel) 2019; 8:antibiotics8040241. [PMID: 31795127 PMCID: PMC6963206 DOI: 10.3390/antibiotics8040241] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 11/21/2019] [Accepted: 11/25/2019] [Indexed: 12/14/2022] Open
Abstract
Staphylococcus aureus is a facultative intracellular pathogen that invades and replicates within many types of human cells. S. aureus has shown to rapidly overcome traditional antibiotherapy by developing multidrug resistance. Furthermore, intracellular S. aureus is protected from the last-resort antibiotics—vancomycin, daptomycin, and linezolid—as they are unable to achieve plasma concentrations sufficient for intracellular killing. Therefore, there is an urgent need to develop novel anti-infective therapies against S. aureus infections. Here, we review the current state of the field and highlight the exploitation of host-directed approaches as a promising strategy going forward.
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10
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Melcarne C, Lemaitre B, Kurant E. Phagocytosis in Drosophila: From molecules and cellular machinery to physiology. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 109:1-12. [PMID: 30953686 DOI: 10.1016/j.ibmb.2019.04.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 03/22/2019] [Accepted: 04/01/2019] [Indexed: 05/20/2023]
Abstract
Phagocytosis is an evolutionarily conserved mechanism that plays a key role in both host defence and tissue homeostasis in multicellular organisms. A range of surface receptors expressed on different cell types allow discriminating between self and non-self (or altered) material, thus enabling phagocytosis of pathogens and apoptotic cells. The phagocytosis process can be divided into four main steps: 1) binding of the phagocyte to the target particle, 2) particle internalization and phagosome formation, through remodelling of the plasma membrane, 3) phagosome maturation, and 4) particle destruction in the phagolysosome. In this review, we describe our present knowledge on phagocytosis in the fruit fly Drosophila melanogaster, assessing each of the key steps involved in engulfment of both apoptotic cells and bacteria. We also assess the physiological role of phagocytosis in host defence, development and tissue homeostasis.
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Affiliation(s)
- C Melcarne
- Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
| | - B Lemaitre
- Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
| | - E Kurant
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa, 34988, Israel.
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López-Jiménez AT, Cardenal-Muñoz E, Leuba F, Gerstenmaier L, Barisch C, Hagedorn M, King JS, Soldati T. The ESCRT and autophagy machineries cooperate to repair ESX-1-dependent damage at the Mycobacterium-containing vacuole but have opposite impact on containing the infection. PLoS Pathog 2018; 14:e1007501. [PMID: 30596802 PMCID: PMC6329560 DOI: 10.1371/journal.ppat.1007501] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 01/11/2019] [Accepted: 12/03/2018] [Indexed: 12/21/2022] Open
Abstract
Phagocytic cells capture and kill most invader microbes within the bactericidal phagosome, but some pathogens subvert killing by damaging the compartment and escaping to the cytosol. To prevent the leakage of pathogen virulence and host defence factors, as well as bacteria escape, host cells have to contain and repair the membrane damage, or finally eliminate the cytosolic bacteria. All eukaryotic cells engage various repair mechanisms to ensure plasma membrane integrity and proper compartmentalization of organelles, including the Endosomal Sorting Complex Required for Transport (ESCRT) and autophagy machineries. We show that during infection of Dictyostelium discoideum with Mycobacterium marinum, the ESCRT-I component Tsg101, the ESCRT-III protein Snf7/Chmp4/Vps32 and the AAA-ATPase Vps4 are recruited to sites of damage at the Mycobacterium-containing vacuole. Interestingly, damage separately recruits the ESCRT and the autophagy machineries. In addition, the recruitment of Vps32 and Vps4 to repair sterile membrane damage depends on Tsg101 but appears independent of Ca2+. Finally, in absence of Tsg101, M. marinum accesses prematurely the cytosol, where the autophagy machinery restricts its growth. We propose that ESCRT has an evolutionary conserved function to repair small membrane damage and to contain intracellular pathogens in intact compartments. Upon uptake by a host cell, intracellular pathogens reside in a membranous compartment called phagosome. Within the phagosome, microbes are protected from the extracellular and cytosolic immune defences, whilst access to nutrients is limited. Some microbes gain access to the host cytosol by damaging the membrane of the phagosome, a step preceding egress and dissemination. Autophagy, a major catabolic pathway in eukaryotes, has been previously proposed to contribute to autonomous cell defence and to repair the membrane damage induced by intracellular pathogens. Here, we provide evidence that, in Dictyostelium discoideum, autophagy does not work alone in the containment of vacuolar mycobacteria, but it operates together with the Endosomal Sorting Complex Required for Transport (ESCRT), a protein machinery recently shown to repair endolysosomal damage. We demonstrate that the membrane perforations induced by the ESX-1 secretion system of Mycobacterium marinum are targeted by both ESCRT and autophagy, which seal the damaged vacuole. We propose that ESCRT might mend small membrane pores, whilst autophagy patches larger cumulative wounds. Interestingly, and contrary to what has been described in mammalian cells for ESCRT-dependent endolysosomal repair, in D. discoideum, repair of sterile membrane damage appears not to require Ca2+. The evolutionary conservation of the function of ESCRT in membrane repair suggests that this machinery plays an ancestral and widespread role to contain a broad range of intracellular pathogens.
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Affiliation(s)
- Ana T. López-Jiménez
- Department of Biochemistry, Faculty of Science, University of Geneva, Sciences II, Geneva, Switzerland
| | - Elena Cardenal-Muñoz
- Department of Biochemistry, Faculty of Science, University of Geneva, Sciences II, Geneva, Switzerland
| | - Florence Leuba
- Department of Biochemistry, Faculty of Science, University of Geneva, Sciences II, Geneva, Switzerland
| | - Lilli Gerstenmaier
- Section Parasitology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Caroline Barisch
- Department of Biochemistry, Faculty of Science, University of Geneva, Sciences II, Geneva, Switzerland
| | - Monica Hagedorn
- Life Sciences and Chemistry, Jacobs University Bremen gGmbH, group Ribogenetics, Bremen, Germany
| | - Jason S. King
- Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield, United Kingdom
| | - Thierry Soldati
- Department of Biochemistry, Faculty of Science, University of Geneva, Sciences II, Geneva, Switzerland
- * E-mail:
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12
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Mycobacterium tuberculosis Type VII Secretion System Effectors Differentially Impact the ESCRT Endomembrane Damage Response. mBio 2018; 9:mBio.01765-18. [PMID: 30482832 PMCID: PMC6282207 DOI: 10.1128/mbio.01765-18] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Intracellular pathogens have varied strategies to breach the endolysosomal barrier so that they can deliver effectors to the host cytosol, access nutrients, replicate in the cytoplasm, and avoid degradation in the lysosome. In the case of Mycobacterium tuberculosis, the bacterium perforates the phagosomal membrane shortly after being taken up by macrophages. Phagosomal damage depends upon the mycobacterial ESX-1 type VII secretion system (T7SS). Sterile insults, such as silica crystals or membranolytic peptides, can also disrupt phagosomal and endolysosomal membranes. Recent work revealed that the host endosomal sorting complex required for transport (ESCRT) machinery rapidly responds to sterile endolysosomal damage and promotes membrane repair. We hypothesized that ESCRTs might also respond to pathogen-induced phagosomal damage and that M. tuberculosis could impair this host response. Indeed, we found that ESCRT-III proteins were recruited to M. tuberculosis phagosomes in an ESX-1-dependent manner. We previously demonstrated that the mycobacterial effectors EsxG/TB9.8 and EsxH/TB10.4, both secreted by the ESX-3 T7SS, can inhibit ESCRT-dependent trafficking of receptors to the lysosome. Here, we additionally show that ESCRT-III recruitment to sites of endolysosomal damage is antagonized by EsxG and EsxH, both within the context of M. tuberculosis infection and sterile injury. Moreover, EsxG and EsxH themselves respond within minutes to membrane damage in a manner that is independent of calcium and ESCRT-III recruitment. Thus, our study reveals that T7SS effectors and ESCRT participate in a series of measures and countermeasures for control of phagosome integrity.IMPORTANCE Mycobacterium tuberculosis causes tuberculosis, which kills more people than any other infection. M. tuberculosis grows in macrophages, cells that specialize in engulfing and degrading microorganisms. Like many intracellular pathogens, in order to cause disease, M. tuberculosis damages the membrane-bound compartment (phagosome) in which it is enclosed after macrophage uptake. Recent work showed that when chemicals damage this type of intracellular compartment, cells rapidly detect and repair the damage, using machinery called the endosomal sorting complex required for transport (ESCRT). Therefore, we hypothesized that ESCRT might also respond to pathogen-induced damage. At the same time, our previous work showed that the EsxG-EsxH heterodimer of M. tuberculosis can inhibit ESCRT, raising the possibility that M. tuberculosis impairs this host response. Here, we show that ESCRT is recruited to damaged M. tuberculosis phagosomes and that EsxG-EsxH undermines ESCRT-mediated endomembrane repair. Thus, our studies demonstrate a battle between host and pathogen over endomembrane integrity.
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13
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Skowyra ML, Schlesinger PH, Naismith TV, Hanson PI. Triggered recruitment of ESCRT machinery promotes endolysosomal repair. Science 2018; 360:360/6384/eaar5078. [PMID: 29622626 PMCID: PMC6195421 DOI: 10.1126/science.aar5078] [Citation(s) in RCA: 289] [Impact Index Per Article: 48.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 02/16/2018] [Indexed: 12/15/2022]
Abstract
Endolysosomes can be damaged by diverse materials. Terminally damaged compartments are degraded by lysophagy, but pathways that repair salvageable organelles are poorly understood. Here we found that the endosomal sorting complex required for transport (ESCRT) machinery, known to mediate budding and fission on endolysosomes, also plays an essential role in their repair. ESCRTs were rapidly recruited to acutely injured endolysosomes through a pathway requiring calcium and ESCRT-activating factors that was independent of lysophagy. We used live-cell imaging to demonstrate that ESCRTs responded to small perforations in endolysosomal membranes and enabled compartments to recover from limited damage. Silica crystals that disrupted endolysosomes also triggered ESCRT recruitment. ESCRTs thus provide a defense against endolysosomal damage likely to be relevant in physiological and pathological contexts.
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Affiliation(s)
- Michael L Skowyra
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Paul H Schlesinger
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Teresa V Naismith
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Phyllis I Hanson
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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14
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The eIF2α Kinase Heme-Regulated Inhibitor Protects the Host from Infection by Regulating Intracellular Pathogen Trafficking. Infect Immun 2018; 86:IAI.00707-17. [PMID: 29311243 DOI: 10.1128/iai.00707-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 12/19/2017] [Indexed: 12/20/2022] Open
Abstract
The host employs both cell-autonomous and system-level responses to limit pathogen replication in the initial stages of infection. Previously, we reported that the eukaryotic initiation factor 2α (eIF2α) kinases heme-regulated inhibitor (HRI) and protein kinase R (PKR) control distinct cellular and immune-related activities in response to diverse bacterial pathogens. Specifically for Listeria monocytogenes, there was reduced translocation of the pathogen to the cytosolic compartment in HRI-deficient cells and consequently reduced loading of pathogen-derived antigens on major histocompatibility complex class I (MHC-I) complexes. Here we show that Hri-/- mice, as well as wild-type mice treated with an HRI inhibitor, are more susceptible to listeriosis. In the first few hours of L. monocytogenes infection, there was much greater pathogen proliferation in the liver of Hri-/- mice than in the liver of Hri+/+ mice. Further, there was a rapid increase of serum interleukin-6 (IL-6) levels in Hri+/+ mice in the first few hours of infection whereas the increase in IL-6 levels in Hri-/- mice was notably delayed. Consistent with these in vivo findings, the rate of listeriolysin O (LLO)-dependent pathogen efflux from infected Hri-/- macrophages and fibroblasts was significantly higher than the rate seen with infected Hri+/+ cells. Treatment of cells with an eIF2α kinase activator enhanced both the HRI-dependent and PKR-dependent infection phenotypes, further indicating the pharmacologically malleability of this signaling pathway. Collectively, these results suggest that HRI mediates the cellular confinement and killing of virulent L. monocytogenes in addition to promoting a system-level cytokine response and that both are required to limit pathogen replication during the first few hours of infection.
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15
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Advances in Myeloid-Like Cell Origins and Functions in the Model Organism Drosophila melanogaster. Microbiol Spectr 2017; 5. [PMID: 28102122 DOI: 10.1128/microbiolspec.mchd-0038-2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Drosophila has long served as a valuable model for deciphering many biological processes, including immune responses. Indeed, the genetic tractability of this organism is particularly suited for large-scale analyses. Studies performed during the last 3 decades have proven that the signaling pathways that regulate the innate immune response are conserved between Drosophila and mammals. This review summarizes the recent advances on Drosophila hematopoiesis and immune cellular responses, with a particular emphasis on phagocytosis.
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16
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Thornbrough JM, Gopinath A, Hundley T, Worley MJ. Human Genome-Wide RNAi Screen for Host Factors That Facilitate Salmonella Invasion Reveals a Role for Potassium Secretion in Promoting Internalization. PLoS One 2016; 11:e0166916. [PMID: 27880807 PMCID: PMC5120809 DOI: 10.1371/journal.pone.0166916] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 11/07/2016] [Indexed: 02/06/2023] Open
Abstract
Salmonella enterica can actively invade the gastro-intestinal epithelium. This frequently leads to diarrheal disease, and also gives the pathogen access to phagocytes that can serve as vehicles for dissemination into deeper tissue. The ability to invade host cells is also important in maintaining the carrier state. While much is known about the bacterial factors that promote invasion, relatively little is known about the host factors involved. To gain insight into how Salmonella enterica serovar Typhimurium is able to invade normally non-phagocytic cells, we undertook a global RNAi screen with S. Typhimurium-infected human epithelial cells. In all, we identified 633 genes as contributing to bacterial internalization. These genes fall into a diverse group of functional categories revealing that cytoskeletal regulators are not the only factors that modulate invasion. In fact, potassium ion transport was the most enriched molecular function category in our screen, reinforcing a link between potassium and internalization. In addition to providing new insights into the molecular mechanisms underlying the ability of pathogens to invade host cells, all 633 host factors identified are candidates for new anti-microbial targets for treating Salmonella infections, and may be useful in curtailing infections with other pathogens as well.
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Affiliation(s)
- Joshua M. Thornbrough
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
| | - Adarsh Gopinath
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
| | - Tom Hundley
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
| | - Micah J. Worley
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
- Department of Microbiology and Immunology, University of Louisville, Louisville, KY, 40202, United States of America
- * E-mail:
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17
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Rengarajan M, Hayer A, Theriot JA. Endothelial Cells Use a Formin-Dependent Phagocytosis-Like Process to Internalize the Bacterium Listeria monocytogenes. PLoS Pathog 2016; 12:e1005603. [PMID: 27152864 PMCID: PMC4859537 DOI: 10.1371/journal.ppat.1005603] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 04/06/2016] [Indexed: 01/11/2023] Open
Abstract
Vascular endothelial cells act as gatekeepers that protect underlying tissue from blood-borne toxins and pathogens. Nevertheless, endothelial cells are able to internalize large fibrin clots and apoptotic debris from the bloodstream, although the precise mechanism of such phagocytosis-like uptake is unknown. We show that cultured primary human endothelial cells (HUVEC) internalize both pathogenic and non-pathogenic Listeria bacteria comparably, in a phagocytosis-like process. In contrast with previously studied host cell types, including intestinal epithelial cells and hepatocytes, we find that endothelial internalization of Listeria is independent of all known pathogenic bacterial surface proteins. Consequently, we exploited the internalization and intracellular replication of L. monocytogenes to identify distinct host cell factors that regulate phagocytosis-like uptake in HUVEC. Using siRNA screening and subsequent genetic and pharmacologic perturbations, we determined that endothelial infectivity was modulated by cytoskeletal proteins that normally modulate global architectural changes, including phosphoinositide-3-kinase, focal adhesions, and the small GTPase Rho. We found that Rho kinase (ROCK) is acutely necessary for adhesion of Listeria to endothelial cells, whereas the actin-nucleating formins FHOD1 and FMNL3 specifically regulate internalization of bacteria as well as inert beads, demonstrating that formins regulate endothelial phagocytosis-like uptake independent of the specific cargo. Finally, we found that neither ROCK nor formins were required for macrophage phagocytosis of L. monocytogenes, suggesting that endothelial cells have distinct requirements for bacterial internalization from those of classical professional phagocytes. Our results identify a novel pathway for L. monocytogenes uptake by human host cells, indicating that this wily pathogen can invade a variety of tissues by using a surprisingly diverse suite of distinct uptake mechanisms that operate differentially in different host cell types.
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Affiliation(s)
- Michelle Rengarajan
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
| | - Arnold Hayer
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Julie A. Theriot
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail:
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18
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A Dual Microscopy-Based Assay To Assess Listeria monocytogenes Cellular Entry and Vacuolar Escape. Appl Environ Microbiol 2015; 82:211-7. [PMID: 26497455 DOI: 10.1128/aem.02302-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 10/14/2015] [Indexed: 01/11/2023] Open
Abstract
Listeria monocytogenes is a Gram-positive bacterium and a facultative intracellular pathogen that invades mammalian cells, disrupts its internalization vacuole, and proliferates in the host cell cytoplasm. Here, we describe a novel image-based microscopy assay that allows discrimination between cellular entry and vacuolar escape, enabling high-content screening to identify factors specifically involved in these two steps. We first generated L. monocytogenes and Listeria innocua strains expressing a β-lactamase covalently attached to the bacterial cell wall. These strains were then incubated with HeLa cells containing the Förster resonance energy transfer (FRET) probe CCF4 in their cytoplasm. The CCF4 probe was cleaved by the bacterial surface β-lactamase only in cells inoculated with L. monocytogenes but not those inoculated with L. innocua, thereby demonstrating bacterial access to the host cytoplasm. Subsequently, we performed differential immunofluorescence staining to distinguish extracellular versus total bacterial populations in samples that were also analyzed by the FRET-based assay. With this two-step analysis, bacterial entry can be distinguished from vacuolar rupture in a single experiment. Our novel approach represents a powerful tool for identifying factors that determine the intracellular niche of L. monocytogenes.
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19
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Genome-Wide siRNA Screen Identifies Complementary Signaling Pathways Involved in Listeria Infection and Reveals Different Actin Nucleation Mechanisms during Listeria Cell Invasion and Actin Comet Tail Formation. mBio 2015; 6:e00598-15. [PMID: 25991686 PMCID: PMC4442140 DOI: 10.1128/mbio.00598-15] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Listeria monocytogenes enters nonphagocytic cells by a receptor-mediated mechanism that is dependent on a clathrin-based molecular machinery and actin rearrangements. Bacterial intra- and intercellular movements are also actin dependent and rely on the actin nucleating Arp2/3 complex, which is activated by host-derived nucleation-promoting factors downstream of the cell receptor Met during entry and by the bacterial nucleation-promoting factor ActA during comet tail formation. By genome-wide small interfering RNA (siRNA) screening for host factors involved in bacterial infection, we identified diverse cellular signaling networks and protein complexes that support or limit these processes. In addition, we could precise previously described molecular pathways involved in Listeria invasion. In particular our results show that the requirements for actin nucleators during Listeria entry and actin comet tail formation are different. Knockdown of several actin nucleators, including SPIRE2, reduced bacterial invasion while not affecting the generation of comet tails. Most interestingly, we observed that in contrast to our expectations, not all of the seven subunits of the Arp2/3 complex are required for Listeria entry into cells or actin tail formation and that the subunit requirements for each of these processes differ, highlighting a previously unsuspected versatility in Arp2/3 complex composition and function. Listeria is a bacterial pathogen that induces its internalization within the cytoplasm of human cells and has been used for decades as a major molecular tool to manipulate cells in order to explore and discover cellular functions. We have inactivated individually, for the first time in epithelial cells, all the genes of the human genome to investigate whether each gene modifies positively or negatively the Listeria infectious process. We identified novel signaling cascades that have never been associated with Listeria infection. We have also revisited the role of the molecular complex Arp2/3 involved in the polymerization of the actin cytoskeleton, which was shown previously to be required for Listeria entry and movement inside host cells, and we demonstrate that contrary to the general dogma, some subunits of the complex are dispensable for both Listeria entry and bacterial movement.
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20
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Endocytic pathway mediates refractoriness of insect Bactrocera dorsalis to RNA interference. Sci Rep 2015; 5:8700. [PMID: 25731667 PMCID: PMC4346973 DOI: 10.1038/srep08700] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 02/02/2015] [Indexed: 01/17/2023] Open
Abstract
RNA interference (RNAi) is a powerful and convenient tool for sequence-specific gene silencing, and it is triggered by double-stranded RNA (dsRNA). RNAi can be easily achieved in many eukaryotes by either injecting or feeding dsRNAs. This mechanism has demonstrated its potential in fundamental research on genetics, medicine and agriculture. However, the possibility that insects might develop refractoriness to RNAi remains unexplored. In this study, we report that the oriental fruit fly, Bactrocera dorsalis, became refractory to RNAi using orally administered dsRNA targeting endogenous genes. Furthermore, refractoriness to RNAi is not gene-specific, and its duration depends on the dsRNA concentration. RNAi blockage requires the endocytic pathway. Fluorescence microscopy indicated that in RNAi refractory flies, dsRNA uptake is blocked. Genes involved in the entry of dsRNAs into cells, including chc, cog3, light and others, are down-regulated in RNAi refractory flies. Increasing the endocytic capacity by improving F-actin polymerization disrupts RNAi refractoriness after both primary and secondary dsRNA exposures. Our results demonstrate that an insect can become refractory to RNAi by preventing the entry of dsRNA into its cells.
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21
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Horn L, Leips J, Starz‐Gaiano M. Phagocytic ability declines with age in adult Drosophila hemocytes. Aging Cell 2014; 13:719-28. [PMID: 24828474 PMCID: PMC4116448 DOI: 10.1111/acel.12227] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/24/2014] [Indexed: 12/17/2022] Open
Abstract
Most multicellular organisms show a physiological decline in immune function with age. However, little is known about the mechanisms underlying these changes. We examined Drosophila melanogaster, an important model for identifying genes affecting innate immunity and senescence, to explore the role of phagocytosis in age-related immune dysfunction. We characterized the localized response of immune cells at the dorsal vessel to bacterial infection in 1-week- and 5-week-old flies. We developed a quantitative phagocytosis assay for adult Drosophila and utilized this to characterize the effect of age on phagocytosis in transgenic and natural variant lines. We showed that genes necessary for bacterial engulfment in other contexts are also required in adult flies. We found that blood cells from young and old flies initially engulf bacteria equally well, while cells from older flies accumulate phagocytic vesicles and thus are less capable of destroying pathogens. Our results have broad implications for understanding how the breakdown in cellular processes influences immune function with age.
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Affiliation(s)
- Lucas Horn
- Department of Biological Sciences University of Maryland Baltimore County Baltimore MD 21250USA
| | - Jeff Leips
- Department of Biological Sciences University of Maryland Baltimore County Baltimore MD 21250USA
| | - Michelle Starz‐Gaiano
- Department of Biological Sciences University of Maryland Baltimore County Baltimore MD 21250USA
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22
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Pirruccello M, Nandez R, Idevall-Hagren O, Alcazar-Roman A, Abriola L, Berwick SA, Lucast L, Morel D, De Camilli P. Identification of inhibitors of inositol 5-phosphatases through multiple screening strategies. ACS Chem Biol 2014; 9:1359-68. [PMID: 24742366 PMCID: PMC4076014 DOI: 10.1021/cb500161z] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
![]()
Phosphoinositides are low abundance
membrane phospholipids that
have key roles in signaling, membrane trafficking, and cytoskeletal
dynamics in all cells. Until recently, strategies for robust and quantitative
development of pharmacological tools for manipulating phosphoinositide
levels have focused selectively on PI(3,4,5)P3 due to the
importance of this lipid in growth factor signaling and cell proliferation.
However, drugs that affect levels of other phosphoinositides have
potential therapeutic applications and will be powerful research tools.
Here, we describe methodology for the high-throughput screening of
small molecule modulators of the inositol 5-phosphatases, which dephosphorylate
PI(4,5)P2 (the precursor for PI(3,4,5)P3) and
PI(3,4,5)P3). We developed three complementary in vitro activity assays, tested hit compounds on a panel
of 5-phosphatases, and monitored efficacy toward various substrates.
Two prominent chemical scaffolds were identified with high nanomolar/low
micromolar activity, with one class showing inhibitory activity toward
all 5-phosphatases tested and the other selective activity toward
OCRL and INPP5B, which are closely related to each other. One highly
soluble OCRL/INPP5B-specific inhibitor shows a direct interaction
with the catalytic domain of INPP5B. The efficacy of this compound
in living cells was validated through its property to enhance actin
nucleation at the cell cortex, a PI(4,5)P2 dependent process,
and to inhibit PI(4,5)P2 dephosphorylation by OCRL (both
overexpressed and endogenous enzyme). The assays and screening strategies
described here are applicable to other phosphoinositide-metabolizing
enzymes, at least several of which have major clinical relevance.
Most importantly, this study identifies the first OCRL/INPP5B specific
inhibitor and provides a platform for the design of more potent inhibitors
of this family of enzymes.
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Affiliation(s)
- Michelle Pirruccello
- Department
of Cell Biology, Howard Hughes Medical Institute and Program in Cellular
Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven Connecticut 06510, United States
| | - Ramiro Nandez
- Department
of Cell Biology, Howard Hughes Medical Institute and Program in Cellular
Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven Connecticut 06510, United States
| | - Olof Idevall-Hagren
- Department
of Cell Biology, Howard Hughes Medical Institute and Program in Cellular
Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven Connecticut 06510, United States
| | - Abel Alcazar-Roman
- Department
of Cell Biology, Howard Hughes Medical Institute and Program in Cellular
Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven Connecticut 06510, United States
| | - Laura Abriola
- Yale
Center for Molecular Discovery, Yale University, West Haven, Connecticut 06516, United States
| | - Shana Alexandra Berwick
- Department
of Cell Biology, Howard Hughes Medical Institute and Program in Cellular
Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven Connecticut 06510, United States
| | - Louise Lucast
- Department
of Cell Biology, Howard Hughes Medical Institute and Program in Cellular
Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven Connecticut 06510, United States
| | - Dayna Morel
- Department
of Cell Biology, Howard Hughes Medical Institute and Program in Cellular
Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven Connecticut 06510, United States
| | - Pietro De Camilli
- Department
of Cell Biology, Howard Hughes Medical Institute and Program in Cellular
Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven Connecticut 06510, United States
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23
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Colas C, Menezes S, Gutiérrez-Martínez E, Péan CB, Dionne MS, Guermonprez P. An improved flow cytometry assay to monitor phagosome acidification. J Immunol Methods 2014; 412:1-13. [PMID: 24952246 DOI: 10.1016/j.jim.2014.06.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 06/10/2014] [Accepted: 06/10/2014] [Indexed: 12/23/2022]
Abstract
Phago-lysosome formation is important for cell-autonomous immunity to intracellular pathogens, antigen presentation and metabolism. A hallmark feature of phago-lysosomal compartments is that they undergo progressive luminal acidification controlled by the activation of vacuolar V-ATPase. Acidification is required for many enzymatic processes taking place in phago-lysosomes, like proteolysis, and supports the microbicidal activity of macrophages. Here we present a new quantitative methodology to assess phagosome acidification by flow cytometry based on the use of bi-fluorescent particles. This method relies on the use of UV polystyrene beads labelled with the acid sensor pHrodo-succinimidyl ester (pHrodo(TM) SE red) and enables us to dissociate particle association with phagocytes from their engulfment in acidified compartments. This methodology is well suited to monitor the acidification of phagosomes formed in vivo after fluorescent bead administration.
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Affiliation(s)
- Chloé Colas
- Phagocyte Immunobiology Laboratory, Centre for Molecular and Cellular Biology of Inflammation, Peter Gorer Department of Immunobiology, Division of Immunology, Infection & Inflammatory Diseases, King's College London, United Kingdom
| | - Shinelle Menezes
- Phagocyte Immunobiology Laboratory, Centre for Molecular and Cellular Biology of Inflammation, Peter Gorer Department of Immunobiology, Division of Immunology, Infection & Inflammatory Diseases, King's College London, United Kingdom
| | - Enric Gutiérrez-Martínez
- Phagocyte Immunobiology Laboratory, Centre for Molecular and Cellular Biology of Inflammation, Peter Gorer Department of Immunobiology, Division of Immunology, Infection & Inflammatory Diseases, King's College London, United Kingdom
| | - Claire B Péan
- Immunometabolism Laboratory, Centre for Molecular and Cellular Biology of Inflammation, Peter Gorer Department of Immunobiology, Division of Immunology, Infection & Inflammatory Diseases, King's College London, United Kingdom
| | - Marc S Dionne
- Immunometabolism Laboratory, Centre for Molecular and Cellular Biology of Inflammation, Peter Gorer Department of Immunobiology, Division of Immunology, Infection & Inflammatory Diseases, King's College London, United Kingdom
| | - Pierre Guermonprez
- Phagocyte Immunobiology Laboratory, Centre for Molecular and Cellular Biology of Inflammation, Peter Gorer Department of Immunobiology, Division of Immunology, Infection & Inflammatory Diseases, King's College London, United Kingdom.
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24
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Taillebourg E, Schneider DS, Fauvarque MO. The Drosophila deubiquitinating enzyme dUSP36 acts in the hemocytes for tolerance to Listeria monocytogenes infections. J Innate Immun 2014; 6:632-8. [PMID: 24777180 DOI: 10.1159/000360293] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 02/04/2014] [Indexed: 01/07/2023] Open
Abstract
Listeria monocytogenes is a facultative intracellular pathogen which can infect Drosophila melanogaster. Upon infection, Drosophila mounts an immune response including antimicrobial peptide production and autophagy activation. A set of previously published results prompted us to study the role of the deubiquitinating enzyme dUSP36 in response to L. monocytogenes infections. We show in this report that flies with dUsp36-specific inactivation in hemocytes are susceptible to L. monocytogenes infections (as are flies with autophagy-deficient hemocytes) but are still able to control bacterial growth. Interestingly, flies with dUsp36-depleted hemocytes are not sensitized to infection by other pathogens. We conclude that dUsp36 plays a major role in hemocytes for tolerance to L. monocytogenes.
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Affiliation(s)
- Emmanuel Taillebourg
- Department of Microbiology and Immunology, Stanford University, Stanford, Calif., USA
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25
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Lee TH, McKleroy W, Khalifeh-Soltani A, Sakuma S, Lazarev S, Riento K, Nishimura SL, Nichols BJ, Atabai K. Functional genomic screen identifies novel mediators of collagen uptake. Mol Biol Cell 2014; 25:583-93. [PMID: 24403604 PMCID: PMC3937085 DOI: 10.1091/mbc.e13-07-0382] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Tissue fibrosis occurs when matrix production outpaces matrix degradation. Degradation of collagen, the main component of fibrotic tissue, is mediated through an extracellular proteolytic pathway and intracellular pathway of cellular uptake and lysosomal digestion. Recent studies demonstrate that disruption of the intracellular pathways can exacerbate fibrosis. These pathways are poorly characterized. Here we identify novel mediators of the intracellular pathway of collagen turnover through a genome-wide RNA interference screen in Drosophila S2 cells. Screening of 7505 Drosophila genes conserved among metazoans identified 22 genes that were required for efficient internalization of type I collagen. These included proteins involved in vesicle transport, the actin cytoskeleton, and signal transduction. We show further that the flotillin genes have a conserved and central role in collagen uptake in Drosophila and human cells. Short hairpin RNA-mediated silencing of flotillins in human monocyte and fibroblasts impaired collagen uptake by promoting lysosomal degradation of the endocytic collagen receptors uPARAP/Endo180 and mannose receptor. These data provide an initial characterization of intracellular pathways of collagen turnover and identify the flotillin genes as critical regulators of this process. A better understanding of these pathways may lead to novel therapies that reduce fibrosis by increasing collagen turnover.
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Affiliation(s)
- Ting-Hein Lee
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158 Department of Medicine, University of California, San Francisco, San Francisco, CA 94158 Lung Biology Center, University of California, San Francisco, San Francisco, CA 94158 Department of Pathology, University of California, San Francisco, San Francisco, CA 94158 MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
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26
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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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27
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Pandey A, Ding SL, Ficht TA, de Figueiredo P. SiRNA screens using Drosophila cells to identify host factors required for infection. Methods Mol Biol 2014; 1197:229-44. [PMID: 25172284 DOI: 10.1007/978-1-4939-1261-2_13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Drosophila melanogaster offers a powerful model system for interrogating interactions between host cells and human bacterial pathogens. Brucella, a gram-negative, facultative intracellular bacterium is the causative agent of brucellosis, a zoonotic disease of global consequence. Over the past several decades, pathogen factors that mediate Brucella infection have been identified. However, host factors that mediate infection have remained obscure. We have used the power of the Drosophila S2 cell system to identify and characterize host factors that support infection by Brucella melitensis. Host protein inositol-requiring enzyme 1 (IRE1α), a transmembrane kinase and master regulator of the eukaryotic unfolded protein response, was shown to play an important role in regulating Brucella infection, thereby providing the first glimpse of host mechanisms that are subverted by the pathogen to support its intracellular lifestyle. Furthermore, our study also established the Drosophila S2 cell as a powerful system for elucidating Brucella host factors. Here, we describe a protocol for using the Drosophila S2 cell system for studying the Brucella-host interaction.
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Affiliation(s)
- Aseem Pandey
- Department of Veterinary Pathobiology, Texas A&M University, 4474 TAMU, College Station, TX, 77843, USA,
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28
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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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Kühbacher A, Gouin E, Mercer J, Emmenlauer M, Dehio C, Cossart P, Pizarro-Cerdá J. Imaging InlC secretion to investigate cellular infection by the bacterial pathogen Listeria monocytogenes. J Vis Exp 2013:e51043. [PMID: 24084755 DOI: 10.3791/51043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Bacterial intracellular pathogens can be conceived as molecular tools to dissect cellular signaling cascades due to their capacity to exquisitely manipulate and subvert cell functions which are required for the infection of host target tissues. Among these bacterial pathogens, Listeria monocytogenes is a Gram positive microorganism that has been used as a paradigm for intracellular parasitism in the characterization of cellular immune responses, and which has played instrumental roles in the discovery of molecular pathways controlling cytoskeletal and membrane trafficking dynamics. In this article, we describe a robust microscopical assay for the detection of late cellular infection stages of L. monocytogenes based on the fluorescent labeling of InlC, a secreted bacterial protein which accumulates in the cytoplasm of infected cells; this assay can be coupled to automated high-throughput small interfering RNA screens in order to characterize cellular signaling pathways involved in the up- or down-regulation of infection.
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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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Shandala T, Lim C, Sorvina A, Brooks DA. A Drosophila model to image phagosome maturation. Cells 2013; 2:188-201. [PMID: 24709696 PMCID: PMC3972680 DOI: 10.3390/cells2020188] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 02/21/2013] [Accepted: 03/14/2013] [Indexed: 12/23/2022] Open
Abstract
Phagocytosis involves the internalization of extracellular material by invagination of the plasma membrane to form intracellular vesicles called phagosomes, which have functions that include pathogen degradation. The degradative properties of phagosomes are thought to be conferred by sequential fusion with endosomes and lysosomes; however, this maturation process has not been studied in vivo. We employed Drosophila hemocytes, which are similar to mammalian professional macrophages, to establish a model of phagosome maturation. Adult Drosophila females, carrying transgenic Rab7-GFP endosome and Lamp1-GFP lysosome markers, were injected with E. coli DH5α and the hemocytes were collected at 15, 30, 45 and 60 minutes after infection. In wild-type females, E. coli were detected within enlarged Rab7-GFP positive phagosomes at 15 to 45 minutes after infection; and were also observed in enlarged Lamp1-GFP positive phagolysosomes at 45 minutes. Two-photon imaging of hemocytes in vivo confirmed this vesicle morphology, including enlargement of Rab7-GFP and Lamp1-GFP structures that often appeared to protrude from hemocytes. The interaction of endosomes and lysosomes with E. coli phagosomes observed in Drosophila hemocytes was consistent with that previously described for phagosome maturation in human ex vivo macrophages. We also tested our model as a tool for genetic analysis using 14-3-3ε mutants, and demonstrated altered phagosome maturation with delayed E. coli internalization, trafficking and/or degradation. These findings demonstrate that Drosophila hemocytes provide an appropriate, genetically amenable, model for analyzing phagosome maturation ex vivo and in vivo.
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Affiliation(s)
- Tetyana Shandala
- Mechanisms in Cell Biology and Diseases Research Group, School of Pharmacy and Medical Science, Sansom Institute for Health Research, University of South Australia, Adelaide, SA 5001, Australia.
| | - Chiaoxin Lim
- Mechanisms in Cell Biology and Diseases Research Group, School of Pharmacy and Medical Science, Sansom Institute for Health Research, University of South Australia, Adelaide, SA 5001, Australia.
| | - Alexandra Sorvina
- Mechanisms in Cell Biology and Diseases Research Group, School of Pharmacy and Medical Science, Sansom Institute for Health Research, University of South Australia, Adelaide, SA 5001, Australia.
| | - Douglas A Brooks
- Mechanisms in Cell Biology and Diseases Research Group, School of Pharmacy and Medical Science, Sansom Institute for Health Research, University of South Australia, Adelaide, SA 5001, Australia.
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Eicher SC, Dehio C. Systems-level analysis of host-pathogen interaction using RNA interference. N Biotechnol 2013; 30:308-13. [PMID: 23395778 DOI: 10.1016/j.nbt.2013.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 01/16/2013] [Indexed: 10/27/2022]
Abstract
Hand-in-hand with the availability of full genome sequences for eukaryotic model organisms and humans the demand for analysis of gene function on a system level has grown. In a process called RNA interference (RNAi) specific mRNA species can be degraded by introduction of double-stranded small interfering RNAs (siRNAs) that are complementary to the targeted transcript sequence. This enables the selective impairment of gene function. During the past decade RNAi has been exploited in many different eukaryotic cell types and model organisms. Large-scale and eventually genome-wide RNAi screens ablating gene functions in a systematic manner have delivered an overwhelming amount of data on the requirement of distinct gene products for major cellular pathways. A large part of the RNAi field is dedicated to disease states such as cancer or infection with the prospect of discovering pathways suitable for new therapeutic interventions. Here some of the major steps in the development of the RNAi technology will be outlined and exemplified with a focus on the progress made in the field of mammalian host-pathogen interactions.
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Affiliation(s)
- Simone C Eicher
- Focal Area Infection Biology, Biozentrum of the University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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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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Peltan A, Briggs L, Matthews G, Sweeney ST, Smith DF. Identification of Drosophila gene products required for phagocytosis of Leishmania donovani. PLoS One 2012; 7:e51831. [PMID: 23272175 PMCID: PMC3521716 DOI: 10.1371/journal.pone.0051831] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Accepted: 11/13/2012] [Indexed: 01/07/2023] Open
Abstract
The identity and function of host factors required for efficient phagocytosis and intracellular maintenance of the protozoan parasite Leishmania donovani are poorly understood. Utilising the phagocytic capability of Drosophila S2 cells, together with available tools for modulating gene expression by RNAi, we have developed an experimental system in which to identify host proteins of this type on a genome-wide scale. We have shown that L. donovani amastigotes can be phagocytosed by S2 cells, in which they replicate and are maintained in a compartment with features characteristic of mammalian phagolysosomes. Screening with dsRNAs from 1920 conserved metazoan genes has identified transcripts that, when reduced in expression, cause either increased or decreased phagocytosis. Focussing on genes in the latter class, RNAi-mediated knockdown of the small GTPase Rab5, the prenylated SNARE protein YKT6, one sub-unit of serine palmitoyltransferase (spt2/lace), the Rac1-associated protein Sra1 and the actin cytoskeleton regulatory protein, SCAR, all lead to a significant reduction in parasite phagocytosis. A role for the lace mammalian homologue in amastigote uptake by mammalian macrophages has been verified using the serine palmitoyltransferase inhibitor, myriocin. These observations suggest that this experimental approach has the potential to identify a large number of host effectors required for efficient parasite uptake and maintenance.
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Affiliation(s)
- Adam Peltan
- Centre for Immunology and Infection, University of York, York, United Kingdom
- Department of Biology, Hull-York Medical School, University of York, York, United Kingdom
| | - Laura Briggs
- Department of Biology, Hull-York Medical School, University of York, York, United Kingdom
| | - Gareth Matthews
- Centre for Immunology and Infection, University of York, York, United Kingdom
| | - Sean T. Sweeney
- Department of Biology, Hull-York Medical School, University of York, York, United Kingdom
| | - Deborah F. Smith
- Centre for Immunology and Infection, University of York, York, United Kingdom
- Department of Biology, Hull-York Medical School, University of York, York, United Kingdom
- * E-mail:
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Chambers MC, Lightfield KL, Schneider DS. How the fly balances its ability to combat different pathogens. PLoS Pathog 2012; 8:e1002970. [PMID: 23271964 PMCID: PMC3521699 DOI: 10.1371/journal.ppat.1002970] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Accepted: 08/27/2012] [Indexed: 12/18/2022] Open
Abstract
Health is a multidimensional landscape. If we just consider the host, there are many outputs that interest us: evolutionary fitness determining parameters like fecundity, survival and pathogen clearance as well as medically important health parameters like sleep, energy stores and appetite. Hosts use a variety of effector pathways to fight infections and these effectors are brought to bear differentially. Each pathogen causes a different disease as they have distinct virulence factors and niches; they each warp the health landscape in unique ways. Therefore, mutations affecting immunity can have complex phenotypes and distinct effects on each pathogen. Here we describe how two components of the fly's immune response, melanization and phagocytosis, contribute to the health landscape generated by the transcription factor ets21c (CG2914) and its putative effector, the signaling molecule wntD (CG8458). To probe the landscape, we infect with two pathogens: Listeria monocytogenes, which primarily lives intracellularly, and Streptococcus pneumoniae, which is an extracellular pathogen. Using the diversity of phenotypes generated by these mutants, we propose that survival during a L. monocytogenes infection is mediated by a combination of two host mechanisms: phagocytic activity and melanization; while survival during a S. pneumoniae infection is determined by phagocytic activity. In addition, increased phagocytic activity is beneficial during S. pneumoniae infection but detrimental during L. monocytogenes infection, demonstrating an inherent trade-off in the immune response. The importance of individual immune responses is incredibly infection dependent, and this paper harnesses the variability in two mutant lines to explain the relative importance of two aspects of fly immunity: melanization and phagocytosis. Increased phagocytic activity is beneficial during S. pneumoniae infection due to increased clearance of the extracellular microbe and detrimental during L. monocytogenes infection as it increases the intracellular niche for L. monocytogenes. Outcomes during L. monocytogenes infection are also dependent on melanization capability, which impacts the ability to control extracellular bacteria.
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Affiliation(s)
- Moria C Chambers
- Department of Microbiology and Immunology, Stanford University, Stanford, California, United States of America
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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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Hamilos G, Samonis G, Kontoyiannis DP. Recent Advances in the Use of Drosophila melanogaster as a Model to Study Immunopathogenesis of Medically Important Filamentous Fungi. Int J Microbiol 2012; 2012:583792. [PMID: 22518146 PMCID: PMC3299265 DOI: 10.1155/2012/583792] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 11/07/2011] [Indexed: 01/30/2023] Open
Abstract
Airborne opportunistic fungi, including Aspergillus and other less common saprophytic molds, have recently emerged as important causes of mortality in immunocompromised individuals. Understanding the molecular mechanisms of host-fungal interplay in robust experimental pathosystems is becoming a research priority for development of novel therapeutics to combat these devastating infections. Over the past decade, invertebrate hosts with evolutionarily conserved innate immune signaling pathways and powerful genetics, such as Drosophila melanogaster, have been employed as a means to overcome logistic restrains associated with the use mammalian models of fungal infections. Recent studies in Drosophila models of filamentous fungi demonstrated that several genes implicated in fungal virulence in mammals also play a similarly important pathogenic role in fruit flies, and important host-related aspects in fungal pathogenesis are evolutionarily conserved. In view of recent advances in Drosophila genetics, fruit flies will become an invaluable surrogate model to study immunopathogenesis of fungal diseases.
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Affiliation(s)
- Georgios Hamilos
- Department of Internal Medicine, School of Medicine, University of Crete, Stavrakia, Voutes, 71110 Heraklion, Crete, Greece
| | - George Samonis
- Department of Internal Medicine, School of Medicine, University of Crete, Stavrakia, Voutes, 71110 Heraklion, Crete, Greece
| | - Dimitrios P. Kontoyiannis
- Department of Infectious Diseases, Infection Control and Employee Health, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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Carrasco-Marín E, Rodriguez-Del Rio E, Frande-Cabanes E, Tobes R, Pareja E, Lecea-Cuello MJ, Ruiz-Sáez M, Madrazo-Toca F, Hölscher C, Alvarez-Dominguez C. Phagosomes induced by cytokines function as anti-Listeria vaccines: novel role for functional compartmentalization of STAT-1 protein and cathepsin-D. J Biol Chem 2012; 287:14310-24. [PMID: 22337873 DOI: 10.1074/jbc.m112.348615] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phagosomes are critical compartments for innate immunity. However, their role in the protection against murine listeriosis has not been examined. We describe here that listericidal phago-receptosomes are induced by the function of IFN-γ or IL-6 as centralized compartments for innate and adaptive immunity because they are able to confer protection against murine listeriosis. These phago-receptosomes elicited LLO(91-99)/CD8(+)- and LLO(189-201)/CD4(+)-specific immune responses and recruited mature dendritic cells to the vaccination sites controlled by T cells. Moreover, they present exceptional features as efficient vaccine vectors. First, they compartmentalize a novel listericidal STAT-1-mediated signaling pathway that confines multiple innate immune components to the same environment. Second, they show features of MHC class II antigen-loading competent compartments for cathepsin-D-mediated LLO processing. Third, murine cathepsin-D deficiencies fail to develop protective immunity after vaccination with listericidal phago-receptosomes induced by IFN-γ or IL-6. Therefore, it appears that the connection of STAT-1 and cathepsin-D in a single compartment is relevant for protection against listeriosis.
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Affiliation(s)
- Eugenio Carrasco-Marín
- Grupo de Genómica, Proteómica de Infecciones Bacterianas e Inflamación, Fundación Marqués de Valdecilla-IFIMAV and Hospital Santa Cruz de Liencres, 39120-Santander, Cantabria, Spain
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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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Yang J, Reth M. Drosophila S2 Schneider cells: a useful tool for rebuilding and redesigning approaches in synthetic biology. Methods Mol Biol 2012; 813:331-41. [PMID: 22083752 DOI: 10.1007/978-1-61779-412-4_20] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Synthetic biology is an engineering approach to biology. A synthetic biologist wants to describe biological molecules and their subdomains as well-defined parts of a molecular machine. To achieve this goal, synthetic biologists rebuild minimal functional biological systems from well-defined parts or they design new molecules that do not exist in nature but have new and useful functions. In short, these engineering approaches can be summarized as "rebuild, alter, and understand." The Drosophila S2 Schneider cell is a useful tool for both rebuilding and redesigning approaches. S2 cells are phagocytic cells that easily take up large amounts of DNA from the cell culture. They, thus, have a high cotransfection rate, allowing the coexpression of up to 12 different proteins. We have developed a transient transfection protocol allowing the rapid and parallel analysis of wild-type and altered forms of a biological system. This chapter describes our methods to rebuild and better understand mammalian signaling systems in the evolutionary distant environment of Drosophila S2 cells.
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Affiliation(s)
- Jianying Yang
- Faculty of Biology, BIOSS Centre for Biological Signalling Studies, University of Freiburg, Max-Planck-Institute of Immunobiology and Epigenetics, Freiburg, Germany
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Lam GY, Czuczman MA, Higgins DE, Brumell JH. Interactions of Listeria monocytogenes with the Autophagy System of Host Cells. Adv Immunol 2012; 113:7-18. [DOI: 10.1016/b978-0-12-394590-7.00008-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Abstract
Many of the cellular mechanisms underlying host responses to pathogens have been well conserved during evolution. As a result, Drosophila can be used to deconstruct many of the key events in host-pathogen interactions by using a wealth of well-developed molecular and genetic tools. In this review, we aim to emphasize the great leverage provided by the suite of genomic and classical genetic approaches available in flies for decoding details of host-pathogen interactions; these findings can then be applied to studies in higher organisms. We first briefly summarize the general strategies by which Drosophila resists and responds to pathogens. We then focus on how recently developed genome-wide RNA interference (RNAi) screens conducted in cells and flies, combined with classical genetic methods, have provided molecular insight into host-pathogen interactions, covering examples of bacteria, fungi and viruses. Finally, we discuss novel strategies for how flies can be used as a tool to examine how specific isolated virulence factors act on an intact host.
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Affiliation(s)
- Ethan Bier
- University of California, San Diego, La Jolla, CA 92039, USA.
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Abstract
In mammals, phagocytosis coordinates host defence on two levels: It acts both as an effector of the innate immunity, as well as an initiator of the adaptive immunity. The fruit fly Drosophila melanogaster (D. melanogaster) lacks the adaptive immune response, and the role of Drosophila plasmatocytes, cells that resemble phagocytosing mammalian macrophages, is limited to innate immune responses. During the past years, several studies have shed light on the role of phagocytosis in the Drosophila host defence. At least in some infection models, the systemic production of potent antimicrobial peptides (AMPs) does not completely compensate for the need for cellular immune responses. As a model, Drosophila offers powerful tools for studying phagocytosis including, large-scale RNA interference (RNAi) based in vitro screens that can be combined with classical Drosophila genetics. These kinds of approaches have led to important discoveries related especially to microbial recognition by Drosophila plasmatocytes. Events following initial recognition, however, have remained more elusive. This review summarizes the current knowledge on Drosophila phagocytosis focusing on the most recent advancements in the field, and highlighting the benefits the Drosophila system has to offer for research on phagocytosis.
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RNAi screen of Salmonella invasion shows role of COPI in membrane targeting of cholesterol and Cdc42. Mol Syst Biol 2011; 7:474. [PMID: 21407211 PMCID: PMC3094068 DOI: 10.1038/msb.2011.7] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 02/03/2011] [Indexed: 01/08/2023] Open
Abstract
A genome wide RNAi screen identifies 72 host cell genes affecting S. Typhimurium entry, including actin regulators and COPI. This study implicates COPI-dependent cholesterol and sphingolipid localization as a common mechanism of infection by bacterial and viral pathogens. Genome-scale RNAi screen identifies 72 host genes affecting S. Typhimurium host cell invasion. Step-specific follow-up assays assign the phenotypes to specific steps of the invasion process. COPI effects on host cell binding, ruffling and invasion were traced to a key role of COPI in membrane targeting of cholesterol, sphingolipids, Rac1 and Cdc42. This new role of COPI explains why COPI is required for host cell infection by numerous bacterial and viral pathogens.
Pathogens are not only a menace to public health, but they also provide excellent tools for probing host cell function. Thus, studying infection mechanisms has fueled progress in cell biology (Ridley et al, 1992; Welch et al, 1997). In the presented study, we have performed an RNAi screen to identify host cell genes required for Salmonella host cell invasion. This screen identified proteins known to contribute to Salmonella-induced actin rearrangements (e.g., Cdc42 and the Arp2/3 complex; reviewed in Schlumberger and Hardt, 2006) and vesicular traffic (e.g., Rab7) as well as unexpected hits, such as the COPI complex. COPI is a known organizer of Golgi-to-ER vesicle transport (Bethune et al, 2006; Beck et al, 2009). Here, we show that COPI is also involved in plasma membrane targeting of cholesterol, sphingolipids and the Rho GTPases Cdc42 and Rac1, essential host cell factors required for Salmonella invasion. This explains why COPI depletion inhibits infection by S. Typhimurium and illustrates how combining bacterial pathogenesis and systems approaches can promote cell biology. Salmonella Typhimurium is a common food-borne pathogen and worldwide a major public health problem causing severe diarrhea. The pathogen uses the host's gut mucosa as a portal of entry and gut tissue invasion is a key event leading to the disease. This explains the intense interest from medicine and basic biology in the mechanism of Salmonella host cell invasion. Tissue culture infection models have delineated a sequence of events leading host cell invasion (Figure 1;Schlumberger and Hardt, 2006): (i) pathogen binding to the host cell surface; (ii) activation of a syringe-like apparatus (‘Type III secretion system 1', T1) of the bacterium and injection of a bacterial toxin cocktail into the host cell. These toxins include SopE, a key virulence factor triggering invasion (Hardt et al, 1998), which was analyzed in our study; (iii) toxin-triggered membrane ruffling. To a significant extent, this is facilitated by SopE-triggered activation of Cdc42 and Rac1 and subsequent actin polymerization at the site of infection; (iv) engulfment of the pathogen within a vesicular compartment (SCV) and (v) maturation of the SCV, a process driven by a second Type III secretion system (T2), which is expressed by the pathogen upon bacterial entry (Figure 1). This sequence of events mediates Salmonella invasion into the gut epithelium and illustrates that this pathogen can be used for probing mechanisms of host cell actin control, membrane biogenesis, vesicle formation and vesicular trafficking. SopE is a key virulence factor of invasion and triggers the activation of Cdc42 and Rac1 and subsequent actin polymerization at the site of infection. We have employed a SopE-expressing S. Typhimurium strain and RNAi screening technology to identify host cell factors affecting invasion. First, we developed an automated fluorescence microscopy assay to quantify S. Typhimurium entry in a high-throughput format (Figure 1C). This assay was based on a GFP reporter expressed by the pathogen after invasion and maturation of the SCV. Using this assay, we screened a ‘druggable genome' siRNA library (6978 genes, 3 oligos each, 1 oligo per well) and identified 72 invasion hits. These included established regulators of the actin cytoskeleton (Cdc42, Arp2/3, Nap1; Schlumberger and Hardt, 2006), some of which have not been implicated so far in Salmonella entry (Pfn1, Cap1), as well as proteins not previously thought to influence infection (Atp1a1, Rbx1, COPI complex). Potentially, these hits could affect any step of the invasion process (Figure 1A). In the second stage of the study, we have assigned each ‘invasion hit' to particular steps of the invasion process. For this purpose, we developed step-specific assays for Salmonella binding, injection, ruffling and membrane engulfment and re-screened the genes found as hits in the first screen (four siRNAs per gene). As expected, a significant number of ‘hits' affected binding to the host cell, others affected binding and ruffling (e.g., Pfn1, Itgβ5, Cap1), a few were specific for the ruffling step (e.g., Cdc42) and some affected SCV maturation, namely Rab7a, the trafficking protein Vps39 and the vacuolar proton pump Atp6ap2. Thus, our experimental strategy allowed mechanistic interpretation and linked novel hits to particular phenotypes, thus providing a basis for further studies (Figure 1). COPI depletion impaired effector injection and ruffling. This was surprising, as the COPI complex was known to regulate retrogade Golgi-to-ER transport, but was not expected to affect pathogen interactions at the plasma membrane. Therefore, we have investigated the underlying mechanism. We have observed that COPI depletion entailed dramatic changes in the plasma membrane composition (Figure 6). Cholesterol and sphingolipids, which form domains (‘lipid rafts') in the plasma membrane, were depleted from the cell surface and redirected into a large vesicular compartment. The same was true for the Rho GTPases Rac1 and Cdc42. This strong decrease in the amount of cholesterol-enriched microdomains and Rho GTPases in the plasma membrane explained the observed defects in S. Typhimurium host cell invasion and assigned a novel role for COPI in controlling mammalian plasma membrane composition. It should be noted that other viral and bacterial pathogens do show a similar dependency on host cellular COPI and plasma membrane lipids. This includes notorious pathogens such as Staphylococcus aureus (Ramet et al, 2002; Potrich et al, 2009), Listeria monocytogenes (Seveau et al, 2004; Agaisse et al, 2005; Cheng et al, 2005; Gekara et al, 2005), Mycobacterium tuberculosis (Munoz et al, 2009), Chlamydia trachomatis (Elwell et al, 2008), influenza virus (Hao et al, 2008; Konig et al, 2010), hepatitis C virus (Tai et al, 2009; Popescu and Dubuisson, 2010) and the vesicular stomatitis virus (presented study) and suggests that COPI-mediated control of host cell plasma membrane composition might be of broad importance for pathogenesis. Future work will have to address whether this might offer starting points for developing anti-infective therapeutics with a very broad spectrum of activity. The pathogen Salmonella Typhimurium is a common cause of diarrhea and invades the gut tissue by injecting a cocktail of virulence factors into epithelial cells, triggering actin rearrangements, membrane ruffling and pathogen entry. One of these factors is SopE, a G-nucleotide exchange factor for the host cellular Rho GTPases Rac1 and Cdc42. How SopE mediates cellular invasion is incompletely understood. Using genome-scale RNAi screening we identified 72 known and novel host cell proteins affecting SopE-mediated entry. Follow-up assays assigned these ‘hits' to particular steps of the invasion process; i.e., binding, effector injection, membrane ruffling, membrane closure and maturation of the Salmonella-containing vacuole. Depletion of the COPI complex revealed a unique effect on virulence factor injection and membrane ruffling. Both effects are attributable to mislocalization of cholesterol, sphingolipids, Rac1 and Cdc42 away from the plasma membrane into a large intracellular compartment. Equivalent results were obtained with the vesicular stomatitis virus. Therefore, COPI-facilitated maintenance of lipids may represent a novel, unifying mechanism essential for a wide range of pathogens, offering opportunities for designing new drugs.
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Qin QM, Luo J, Lin X, Pei J, Li L, Ficht TA, de Figueiredo P. Functional analysis of host factors that mediate the intracellular lifestyle of Cryptococcus neoformans. PLoS Pathog 2011; 7:e1002078. [PMID: 21698225 PMCID: PMC3116820 DOI: 10.1371/journal.ppat.1002078] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 04/07/2011] [Indexed: 11/18/2022] Open
Abstract
Cryptococcus neoformans (Cn), the major causative agent of human fungal meningoencephalitis, replicates within phagolysosomes of infected host cells. Despite more than a half-century of investigation into host-Cn interactions, host factors that mediate infection by this fungal pathogen remain obscure. Here, we describe the development of a system that employs Drosophila S2 cells and RNA interference (RNAi) to define and characterize Cn host factors. The system recapitulated salient aspects of fungal interactions with mammalian cells, including phagocytosis, intracellular trafficking, replication, cell-to-cell spread and escape of the pathogen from host cells. Fifty-seven evolutionarily conserved host factors were identified using this system, including 29 factors that had not been previously implicated in mediating fungal pathogenesis. Subsequent analysis indicated that Cn exploits host actin cytoskeletal elements, cell surface signaling molecules, and vesicle-mediated transport proteins to establish a replicative niche. Several host molecules known to be associated with autophagy (Atg), including Atg2, Atg5, Atg9 and Pi3K59F (a class III PI3-kinase) were also uncovered in our screen. Small interfering RNA (siRNA) mediated depletion of these autophagy proteins in murine RAW264.7 macrophages demonstrated their requirement during Cn infection, thereby validating findings obtained using the Drosophila S2 cell system. Immunofluorescence confocal microscopy analyses demonstrated that Atg5, LC3, Atg9a were recruited to the vicinity of Cn containing vacuoles (CnCvs) in the early stages of Cn infection. Pharmacological inhibition of autophagy and/or PI3-kinase activity further demonstrated a requirement for autophagy associated host proteins in supporting infection of mammalian cells by Cn. Finally, systematic trafficking studies indicated that CnCVs associated with Atg proteins, including Atg5, Atg9a and LC3, during trafficking to a terminal intracellular compartment that was decorated with the lysosomal markers LAMP-1 and cathepsin D. Our findings validate the utility of the Drosophila S2 cell system as a functional genomic platform for identifying and characterizing host factors that mediate fungal intracellular replication. Our results also support a model in which host Atg proteins mediate Cn intracellular trafficking and replication.
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Affiliation(s)
- Qing-Ming Qin
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
- Borlaug Advanced Research Center, Texas A&M University, College Station, Texas, United States of America
- * E-mail: (QMQ); (PdF)
| | - Jijing Luo
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
| | - Xiaorong Lin
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
| | - Jianwu Pei
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America
| | - Lei Li
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
- Borlaug Advanced Research Center, Texas A&M University, College Station, Texas, United States of America
| | - Thomas A. Ficht
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America
| | - Paul de Figueiredo
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
- Borlaug Advanced Research Center, Texas A&M University, College Station, Texas, United States of America
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America
- * E-mail: (QMQ); (PdF)
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Velge P, Roche SM. Variability of Listeria monocytogenes virulence: a result of the evolution between saprophytism and virulence? Future Microbiol 2011; 5:1799-821. [PMID: 21155663 DOI: 10.2217/fmb.10.134] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The genus Listeria consists of eight species but only two are pathogenic. Human listeriosis due to Listeria monocytogenes is a foodborne disease. L. monocytogenes is widespread in the environment living as a saprophyte, but is also capable of making the transition into a pathogen following its ingestion by susceptible humans or animals. It is now known that many distinct strains of L. monocytogenes differ in their virulence and epidemic potential. Unfortunately, there is currently no standard definition of virulence levels and no complete comprehensive overview of the evolution of Listeria species and L. monocytogenes strains taking into account the presence of both epidemic and low-virulence strains. This article focuses on the methods and genes allowing us to determine the pathogenic potential of Listeria strains, and the evolution of Listeria virulence. The presence of variable levels of virulence within L. monocytogenes has important consequences on detection of Listeria strains and risk analysis but also on our comprehension of how certain pathogens will behave in a population over evolutionary time.
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Affiliation(s)
- Philippe Velge
- INRA de tours, UR1282, Infectiologie Animale et Santé Publique, 37380 Nouzilly, France.
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Stavru F, Archambaud C, Cossart P. Cell biology and immunology of Listeria monocytogenes infections: novel insights. Immunol Rev 2011; 240:160-84. [DOI: 10.1111/j.1600-065x.2010.00993.x] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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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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Carrasco-Marín E, Fernández-Prieto L, Rodriguez-Del Rio E, Madrazo-Toca F, Reinheckel T, Saftig P, Alvarez-Dominguez C. LIMP-2 links late phagosomal trafficking with the onset of the innate immune response to Listeria monocytogenes: a role in macrophage activation. J Biol Chem 2011; 286:3332-41. [PMID: 21123180 PMCID: PMC3030339 DOI: 10.1074/jbc.m110.146761] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 10/21/2010] [Indexed: 11/06/2022] Open
Abstract
The innate immune response to Listeria monocytogenes depends on phagosomal bacterial degradation by macrophages. Here, we describe the role of LIMP-2, a lysosomal type III transmembrane glycoprotein and scavenger-like protein, in Listeria phagocytosis. LIMP-2-deficient mice display a macrophage-related defect in Listeria innate immunity. They produce less acute phase pro-inflammatory cytokines/chemokines, MCP-1, TNF-α, and IL-6 but normal levels of IL-12, IL-10, and IFN-γ and a 25-fold increase in susceptibility to Listeria infection. This macrophage defect results in a low listericidal potential, poor response to TNF-α activation signals, impaired phago-lysosome transformation into antigen-processing compartments, and uncontrolled LM cytosolic growth that fails to induce normal levels of acute phase pro-inflammatory cytokines. LIMP-2 transfection of CHO cells confirmed that LIMP-2 participates in the degradation of Listeria within phagosomes, controls the late endosomal/lysosomal fusion machinery, and is linked to the activation of Rab5a. Therefore, the role of LIMP-2 appears to be connected to the TNF-α-dependent and early activation of Listeria macrophages through internal signals linking the regulation of late trafficking events with the onset of the innate Listeria immune response.
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Affiliation(s)
- Eugenio Carrasco-Marín
- From the Servicio de Inmunología, Hospital Santa Cruz de Liencres y Fundación Marqués de Valdecilla-Instituto de Formación e Investigación Marqués de Valdecilla, 39120 Liencres, Spain
| | - Lorena Fernández-Prieto
- From the Servicio de Inmunología, Hospital Santa Cruz de Liencres y Fundación Marqués de Valdecilla-Instituto de Formación e Investigación Marqués de Valdecilla, 39120 Liencres, Spain
| | - Estela Rodriguez-Del Rio
- From the Servicio de Inmunología, Hospital Santa Cruz de Liencres y Fundación Marqués de Valdecilla-Instituto de Formación e Investigación Marqués de Valdecilla, 39120 Liencres, Spain
| | - Fidel Madrazo-Toca
- From the Servicio de Inmunología, Hospital Santa Cruz de Liencres y Fundación Marqués de Valdecilla-Instituto de Formación e Investigación Marqués de Valdecilla, 39120 Liencres, Spain
| | - Thomas Reinheckel
- the Institut für Molekulare Medizin und Zellforschung, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany
| | - Paul Saftig
- the Biochemical Institute, Christian-Albrechts University-Kiel, D-24098 Kiel, Germany, and
| | - Carmen Alvarez-Dominguez
- From the Servicio de Inmunología, Hospital Santa Cruz de Liencres y Fundación Marqués de Valdecilla-Instituto de Formación e Investigación Marqués de Valdecilla, 39120 Liencres, Spain
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Abstract
Lysosomes form part of our innate immunity and are an important line of defence against microbes, viruses and parasites. Although it is more than 50 years since de Duve discovered lysosomes, it is only in more recent years that we are slowly unravelling the molecular mechanisms involved in the delivery of material to the lysosome. However, successful intracellular pathogens often have a better grip on the mechanisms involved in delivery to the lysosome and can manipulate membrane trafficking pathways to create an intracellular environment that is favourable for replication. By studying pathogen effector proteins that are secreted into the host's cytosol, we can learn about both pathogen-survival mechanisms and further regulatory elements involved in trafficking to the lysosome.
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