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Barik S, Andrews J. Host-Parasite Interactions in Toxoplasma gondii-Infected Cells: Roles of Mitochondria, Microtubules, and the Parasitophorous Vacuole. Int J Mol Sci 2024; 25:13459. [PMID: 39769222 PMCID: PMC11677533 DOI: 10.3390/ijms252413459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2024] [Revised: 12/13/2024] [Accepted: 12/13/2024] [Indexed: 01/11/2025] Open
Abstract
An intracellular protozoan, the Apicomplexan parasite Toxoplasma gondii (T. gondii) infects nucleated cells, in which it triggers the formation of a specialized membrane-confined cytoplasmic vacuole, named the parasitophorous vacuole (PV). One of the most prominent events in the parasite's intracellular life is the congregation of the host cell mitochondria around the PV. However, the significance of this event has remained largely unsolved since the parasite itself possesses a functional mitochondrion, which is essential for its replication. Here, we explore several fundamental aspects of the interaction between the PV and the host cell mitochondria. They include the detailed features of the congregation, the nature and mechanism of the mitochondrial travel to the PV, and the potential significance of the migration and congregation. Using a combination of biochemical assays, high-resolution imaging, and RNAi-mediated knockdown, we show that: (i) mitochondrial travel to the PV starts very early in parasite infection, as soon as the smallest PV takes shape; (ii) the travel utilizes the contractile microtubular network of the host cell; and (iii) near the end of the parasitic life cycle, when most PVs have reached their largest sustainable size and are about to lyse in order to release the progeny parasites, the associated mitochondria change their usual elongated shape to small spheres, apparently resulting from increased fission. Intriguingly, despite the well-known mitochondrial role as a major producer of cellular ATP, the parasite does not seem to use cellular mitochondrial ATP. Together, these findings may serve as foundations for future research in host-parasite interaction, particularly in the elucidation of its mechanisms, and the possible development of novel antiparasitic drug regimens.
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2
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Delgado JM, Pernas L. Mitochondria as sensors of intracellular pathogens. Trends Endocrinol Metab 2024:S1043-2760(24)00291-1. [PMID: 39580272 DOI: 10.1016/j.tem.2024.10.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2024] [Revised: 10/22/2024] [Accepted: 10/25/2024] [Indexed: 11/25/2024]
Abstract
Mitochondria must sense their environment to enable cells and organisms to adapt to diverse environments and survive during stress. However, during microbial infection, an evolutionary pressure since the inception of the eukaryotic cell, these organelles are traditionally viewed as targets for microbes. In this opinion we consider the perspective that mitochondria are domesticated microbes that sense and guard their 'host' cell against pathogens. We explore potential mechanisms by which mitochondria detect intracellular pathogens and induce mitochondria-autonomous responses that activate cellular defenses.
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Affiliation(s)
- Jose M Delgado
- Department of Microbiology, Immunology, and Molecular Genetics, University of California Los Angeles, Los Angeles, CA, USA
| | - Lena Pernas
- Department of Microbiology, Immunology, and Molecular Genetics, University of California Los Angeles, Los Angeles, CA, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA; Max Planck Institute for Biology of Ageing, Cologne, Germany.
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3
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Gallego-López GM, Contreras Guzman E, Desa DE, Knoll LJ, Skala MC. Metabolic changes in Toxoplasma gondii-infected host cells measured by autofluorescence imaging. mBio 2024; 15:e0072724. [PMID: 38975793 PMCID: PMC11323734 DOI: 10.1128/mbio.00727-24] [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: 04/05/2024] [Accepted: 05/06/2024] [Indexed: 07/09/2024] Open
Abstract
Toxoplasma gondii, the causative agent of toxoplasmosis, is an obligate intracellular parasite that infects warm-blooded vertebrates across the world. In humans, seropositivity rates of T. gondii range from 10% to 90% across communities. Despite its prevalence, few studies address how T. gondii infection changes the metabolism of host cells. In this study, we investigate how T. gondii manipulates the host cell metabolic environment by monitoring the metabolic response over time using noninvasive autofluorescence lifetime imaging of single cells, metabolite analysis, extracellular flux analysis, and reactive oxygen species (ROS) production. Autofluorescence lifetime imaging indicates that infected host cells become more oxidized and have an increased proportion of bound NAD(P)H compared to uninfected controls. Over time, infected cells also show decreases in levels of intracellular glucose and lactate, increases in oxygen consumption, and variability in ROS production. We further examined changes associated with the pre-invasion "kiss and spit" process using autofluorescence lifetime imaging, which also showed a more oxidized host cell with an increased proportion of bound NAD(P)H over 48 hours compared to uninfected controls, suggesting that metabolic changes in host cells are induced by T. gondii kiss and spit even without invasion.IMPORTANCEThis study sheds light on previously unexplored changes in host cell metabolism induced by T. gondii infection using noninvasive, label-free autofluorescence imaging. In this study, we use optical metabolic imaging (OMI) to measure the optical redox ratio (ORR) in conjunction with fluorescence lifetime imaging microscopy (FLIM) to noninvasively monitor single host cell response to T. gondii infection over 48 hours. Collectively, our results affirm the value of using autofluorescence lifetime imaging to noninvasively monitor metabolic changes in host cells over the time course of a microbial infection. Understanding this metabolic relationship between the host cell and the parasite could uncover new treatment and prevention options for T. gondii infections worldwide.
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Affiliation(s)
- Gina M. Gallego-López
- Morgridge Institute for Research, Madison, Wisconsin, USA
- Department of Medical Microbiology & Immunology, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | | | | | - Laura J. Knoll
- Department of Medical Microbiology & Immunology, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Melissa C. Skala
- Morgridge Institute for Research, Madison, Wisconsin, USA
- Department of Biomedical Engineering, University of Wisconsin–Madison, Madison, Wisconsin, USA
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4
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Rinkenberger N, Rosenberg A, Radke JB, Bhushan J, Tomita T, Weiss LM, Sibley LD. Susceptibility of Toxoplasma gondii to autophagy in human cells relies on multiple interacting parasite loci. mBio 2024; 15:e0259523. [PMID: 38095418 PMCID: PMC10790690 DOI: 10.1128/mbio.02595-23] [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: 09/22/2023] [Accepted: 11/06/2023] [Indexed: 01/04/2024] Open
Abstract
IMPORTANCE Autophagy is a process used by cells to recycle organelles and macromolecules and to eliminate intracellular pathogens. Previous studies have shown that some stains of Toxoplasma gondii are resistant to autophagy-dependent growth restriction, while others are highly susceptible. Although it is known that autophagy-mediated control requires activation by interferon gamma, the basis for why parasite strains differ in their susceptibility is unknown. Our findings indicate that susceptibility involves at least five unlinked parasite genes on different chromosomes, including several secretory proteins targeted to the parasite-containing vacuole and exposed to the host cell cytosol. Our findings reveal that susceptibility to autophagy-mediated growth restriction relies on differential recognition of parasite proteins exposed at the host-pathogen interface, thus identifying a new mechanism for cell-autonomous control of intracellular pathogens.
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Affiliation(s)
- Nicholas Rinkenberger
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Alex Rosenberg
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Joshua B. Radke
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Jaya Bhushan
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Tadakimi Tomita
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Louis M. Weiss
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA
| | - L. David Sibley
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri, USA
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5
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Powell CJ, Jenkins ML, Hill TB, Blank ML, Cabo LF, Thompson LR, Burke JE, Boyle JP, Boulanger MJ. Toxoplasma gondii mitochondrial association factor 1b interactome reveals novel binding partners including Ral GTPase accelerating protein α1. J Biol Chem 2024; 300:105582. [PMID: 38141762 PMCID: PMC10821591 DOI: 10.1016/j.jbc.2023.105582] [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: 06/26/2023] [Revised: 11/22/2023] [Accepted: 12/05/2023] [Indexed: 12/25/2023] Open
Abstract
The intracellular parasite, Toxoplasma gondii, has developed sophisticated molecular strategies to subvert host processes and promote growth and survival. During infection, T. gondii replicates in a parasitophorous vacuole (PV) and modulates host functions through a network of secreted proteins. Of these, Mitochondrial Association Factor 1b (MAF1b) recruits host mitochondria to the PV, a process that confers an in vivo growth advantage, though the precise mechanisms remain enigmatic. To address this knowledge gap, we mapped the MAF1b interactome in human fibroblasts using a commercial Yeast-2-hybrid (Y2H) screen, which revealed several previously unidentified binding partners including the GAP domain of Ral GTPase Accelerating Protein α1 (RalGAPα1(GAP)). Recombinantly produced MAF1b and RalGAPα1(GAP) formed as a stable binary complex as shown by size exclusion chromatography with a Kd of 334 nM as measured by isothermal titration calorimetry (ITC). Notably, no binding was detected between RalGAPα1(GAP) and the structurally conserved MAF1b homolog, MAF1a, which does not recruit host mitochondria. Next, we used hydrogen deuterium exchange mass spectrometry (HDX-MS) to map the RalGAPα1(GAP)-MAF1b interface, which led to identification of the "GAP-binding loop" on MAF1b that was confirmed by mutagenesis and ITC to be necessary for complex formation. A high-confidence Alphafold model predicts the GAP-binding loop to lie at the RalGAPα1(GAP)-MAF1b interface further supporting the HDX-MS data. Mechanistic implications of a RalGAPα1(GAP)-MAF1b complex are discussed in the context of T. gondii infection and indicates that MAF1b may have evolved multiple independent functions to increase T. gondii fitness.
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Affiliation(s)
- Cameron J Powell
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Meredith L Jenkins
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Tara B Hill
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Matthew L Blank
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Leah F Cabo
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Lexie R Thompson
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada; Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Jon P Boyle
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Martin J Boulanger
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada.
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6
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Gallego-López GM, Guzman EC, Knoll LJ, Skala M. Metabolic changes to host cells with Toxoplasma gondii infection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.10.552811. [PMID: 37609172 PMCID: PMC10441426 DOI: 10.1101/2023.08.10.552811] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Toxoplasma gondii, the causative agent of toxoplasmosis, is an obligate intracellular parasite that infects warm-blooded vertebrates across the world. In humans, seropositivity rates of T. gondii range from 10% to 90%. Despite its prevalence, few studies address how T. gondii infection changes the metabolism of host cells. Here, we investigate how T. gondii manipulates the host cell metabolic environment by monitoring metabolic response over time using non-invasive autofluorescence lifetime imaging of single cells, seahorse metabolic flux analysis, reactive oxygen species (ROS) production, and metabolomics. Autofluorescence lifetime imaging indicates that infected host cells become more oxidized and have an increased proportion of bound NAD(P)H with infection. These findings are consistent with changes in mitochondrial and glycolytic function, decrease of intracellular glucose, fluctuations in lactate and ROS production in infected cells over time. We also examined changes associated with the pre-invasion "kiss and spit" process using autofluorescence lifetime imaging, which similarly showed a more oxidized host cell with an increased proportion of bound NAD(P)H over 48 hours. Glucose metabolic flux analysis indicated that these changes are driven by NADH and NADP+ in T. gondii infection. In sum, metabolic changes in host cells with T. gondii infection were similar during full infection, and kiss and spit. Autofluorescence lifetime imaging can non-invasively monitor metabolic changes in host cells over a microbial infection time-course.
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Affiliation(s)
- Gina M. Gallego-López
- Morgridge Institute for Research, Madison, WI, 53706
- Department of Medical Microbiology & Immunology, University of Wisconsin-Madison, Madison, WI, 53706
| | | | - Laura J. Knoll
- Department of Medical Microbiology & Immunology, University of Wisconsin-Madison, Madison, WI, 53706
| | - Melissa Skala
- Morgridge Institute for Research, Madison, WI, 53706
- Department of Biomedical Engineering, University of Wisconsin- Madison, WI 53706, USA
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7
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A. PORTES JULIANA, C. VOMMARO ROSSIANE, AYRES CALDAS LUCIO, S. MARTINS-DUARTE ERICA. Intracellular life of protozoan Toxoplasma gondii: Parasitophorous vacuole establishment and survival strategies. BIOCELL 2023. [DOI: 10.32604/biocell.2023.026629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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8
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Niitepõld K, Parry HA, Harris NR, Appel AG, de Roode JC, Kavazis AN, Hood WR. Flying on empty: Reduced mitochondrial function and flight capacity in food-deprived monarch butterflies. J Exp Biol 2022; 225:275693. [PMID: 35694960 DOI: 10.1242/jeb.244431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 06/07/2022] [Indexed: 11/20/2022]
Abstract
Mitochondrial function is fundamental to organismal performance, health, and fitness - especially during energetically challenging events, such as migration. With this investigation, we evaluated mitochondrial sensitivity to ecologically relevant stressors. We focused on an iconic migrant, the North American monarch butterfly (Danaus plexippus), and examined the effects of two stressors: seven days of food deprivation, and infection by the protozoan parasite Ophryocystis elektroscirrha (known to reduce survival and flight performance). We measured whole-animal resting (RMR) and peak flight metabolic rate, and mitochondrial respiration of isolated mitochondria from the flight muscles. Food deprivation reduced mass-independent RMR and peak flight metabolic rate, whereas infection did not. Fed monarchs used mainly lipids in flight (respiratory quotient 0.73), but the respiratory quotient dropped in food-deprived individuals, possibly indicating switching to alternative energy sources, such as ketone bodies. Food deprivation decreased mitochondrial maximum oxygen consumption but not basal respiration, resulting in lower respiratory control ratio (RCR). Furthermore, food deprivation decreased mitochondrial complex III activity, but increased complex IV activity. Infection did not result in any changes in these mitochondrial variables. Mitochondrial maximum respiration rate correlated positively with mass-independent RMR and flight metabolic rate, suggesting a link between mitochondria and whole-animal performance. In conclusion, low food availability negatively affects mitochondrial function and flight performance, with potential implications on migration, fitness, and population dynamics. Although previous studies have reported poor flight performance in infected monarchs, we found no differences in physiological performance, suggesting that reduced flight capacity may be due to structural differences or low energy stores.
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Affiliation(s)
- Kristjan Niitepõld
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA.,The Finnish Science Centre Heureka, 01300 Vantaa, Finland
| | - Hailey A Parry
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
| | - Natalie R Harris
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Arthur G Appel
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA
| | | | | | - Wendy R Hood
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
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9
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Host cell proteins modulated upon Toxoplasma infection identified using proteomic approaches: a molecular rationale. Parasitol Res 2022; 121:1853-1865. [PMID: 35552534 DOI: 10.1007/s00436-022-07541-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 04/12/2022] [Indexed: 10/18/2022]
Abstract
Toxoplasma gondii is a pathogenic protozoan parasite belonging to the apicomplexan phylum that infects the nucleated cells of warm-blooded hosts leading to an infectious disease known as toxoplasmosis. Apicomplexan parasites such as T. gondii can display different mechanisms to control or manipulate host cells signaling at different levels altering the host subcellular genome and proteome. Indeed, Toxoplasma is able to modulate host cell responses (especially immune responses) during infection to its advantage through both structural and functional changes in the proteome of different infected cells. Consequently, parasites can transform the invaded cells into a suitable environment for its own replication and the induction of infection. Proteomics as an applicable tool can identify such critical proteins involved in pathogen (Toxoplasma)-host cell interactions and consequently clarify the cellular mechanisms that facilitate the entry of pathogens into host cells, and their replication and transmission, as well as the central mechanisms of host defense against pathogens. Accordingly, the current paper reviews several proteins (identified using proteomic approaches) differentially expressed in the proteome of Toxoplasma-infected host cells (macrophages and human foreskin fibroblasts) and tissues (brain and liver) and highlights their plausible functions in the cellular biology of the infected cells. The identification of such modulated proteins and their related cell impact (cell responses/signaling) can provide further information regarding parasite pathogenesis and biology that might lead to a better understanding of therapeutic strategies and novel drug targets.
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10
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Hakimi MA. Hunger games in the host cell: Toxoplasma traps and skins host mitochondria. Cell Host Microbe 2022; 30:274-276. [PMID: 35271796 DOI: 10.1016/j.chom.2022.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Toxoplasma gondii actively tethers host mitochondria to its vacuole, altering their function. In a recent issue of Science, Li et al. demonstrate that Toxoplasma disarms host metabolic defenses by inducing the organelle to shed atypical large structures from its outer membrane to trap mitochondrial proteins that restrict parasite growth.
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Affiliation(s)
- Mohamed-Ali Hakimi
- IAB, Team Host-Pathogen Interactions & Immunity to Infection, INSERM U1209, CNRS UMR 5309, Grenoble Alpes University, 38700 Grenoble, France.
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11
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Li X, Straub J, Medeiros TC, Mehra C, den Brave F, Peker E, Atanassov I, Stillger K, Michaelis JB, Burbridge E, Adrain C, Münch C, Riemer J, Becker T, Pernas LF. Mitochondria shed their outer membrane in response to infection-induced stress. Science 2022; 375:eabi4343. [PMID: 35025629 DOI: 10.1126/science.abi4343] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Xianhe Li
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Julian Straub
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | | | - Chahat Mehra
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Fabian den Brave
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Esra Peker
- Institute of Biochemistry, University of Cologne, Cologne, Germany
| | - Ilian Atanassov
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | | | - Jonas Benjamin Michaelis
- Institute of Biochemistry II, Faculty of Medicine, Goethe University, Frankfurt am Main, Germany
| | - Emma Burbridge
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, Northern Ireland.,Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Colin Adrain
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, Northern Ireland.,Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Christian Münch
- Institute of Biochemistry II, Faculty of Medicine, Goethe University, Frankfurt am Main, Germany
| | - Jan Riemer
- Institute of Biochemistry, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Lena F Pernas
- Max Planck Institute for Biology of Ageing, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
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12
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Toxoplasma gondii GRA28 Is Required for Placenta-Specific Induction of the Regulatory Chemokine CCL22 in Human and Mouse. mBio 2021; 12:e0159121. [PMID: 34781732 PMCID: PMC8593671 DOI: 10.1128/mbio.01591-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Toxoplasma gondii is an intracellular protozoan pathogen of humans that can cross the placenta and result in adverse pregnancy outcomes and long-term birth defects. The mechanisms used by T. gondii to cross the placenta are unknown, but complex interactions with the host immune response are likely to play a role in dictating infection outcomes during pregnancy. Prior work showed that T. gondii infection dramatically and specifically increases the secretion of the immunomodulatory chemokine CCL22 in human placental cells during infection. Given the important role of this chemokine during pregnancy, we hypothesized that CCL22 induction was driven by a specific T. gondii-secreted effector. Using a combination of bioinformatics and molecular genetics, we have now identified T. gondii GRA28 as the gene product required for CCL22 induction. GRA28 is secreted into the host cell, where it localizes to the nucleus, and deletion of the GRA28 gene results in reduced CCL22 placental cells as well as a human monocyte cell line. The impact of GRA28 on CCL22 production is also conserved in mouse immune and placental cells both in vitro and in vivo. Moreover, parasites lacking GRA28 are impaired in their ability to disseminate throughout the animal, suggesting a link between CCL22 induction and the ability of the parasite to cause disease. Overall, these data demonstrate a clear function for GRA28 in altering the immunomodulatory landscape during infection of both placental and peripheral immune cells and show a clear impact of this immunomodulation on infection outcome. IMPORTANCE Toxoplasma gondii is a globally ubiquitous pathogen that can cause severe disease in HIV/AIDS patients and can also cross the placenta and infect the developing fetus. We have found that placental and immune cells infected with T. gondii secrete significant amounts of a chemokine (called CCL22) that is critical for immune tolerance during pregnancy. In order to better understand whether this is a response by the host or a process that is driven by the parasite, we have identified a T. gondii gene that is absolutely required to induce CCL22 production in human cells, indicating that CCL22 production is a process driven almost entirely by the parasite rather than the host. Consistent with its role in immune tolerance, we also found that T. gondii parasites lacking this gene are less able to proliferate and disseminate throughout the host. Taken together, these data illustrate a direct relationship between CCL22 levels in the infected host and a key parasite effector and provide an interesting example of how T. gondii can directly modulate host signaling pathways in order to facilitate its growth and dissemination.
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13
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Toxoplasma gondii association with host mitochondria requires key mitochondrial protein import machinery. Proc Natl Acad Sci U S A 2021; 118:2013336118. [PMID: 33723040 PMCID: PMC7999873 DOI: 10.1073/pnas.2013336118] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Host mitochondrial association (HMA) is a well-known phenomenon during Toxoplasma gondii infection of the host cell. The T. gondii locus mitochondrial association factor 1 (MAF1) is required for HMA and MAF1 encodes distinct paralogs of secreted dense granule effector proteins, some of which mediate the HMA phenotype (MAF1b paralogs drive HMA; MAF1a paralogs do not). To identify host proteins required for MAF1b-mediated HMA, we performed unbiased, label-free quantitative proteomics on host cells infected with type II parasites expressing MAF1b, MAF1a, and an HMA-incompetent MAF1b mutant. Across these samples, we identified ∼1,360 MAF1-interacting proteins, but only 13 that were significantly and uniquely enriched in MAF1b pull-downs. The gene products include multiple mitochondria-associated proteins, including those that traffic to the mitochondrial outer membrane. Based on follow-up endoribonuclease-prepared short interfering RNA (esiRNA) experiments targeting these candidate MAF1b-targeted host factors, we determined that the mitochondrial receptor protein TOM70 and mitochondria-specific chaperone HSPA9 were essential mediators of HMA. Additionally, the enrichment of TOM70 at the parasitophorous vacuole membrane interface suggests parasite-driven sequestration of TOM70 by the parasite. These results show that the interface between the T. gondii vacuole and the host mitochondria is characterized by interactions between a single parasite effector and multiple target host proteins, some of which are critical for the HMA phenotype itself. The elucidation of the functional members of this complex will permit us to explain the link between HMA and changes in the biology of the host cell.
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14
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Medeiros TC, Mehra C, Pernas L. Contact and competition between mitochondria and microbes. Curr Opin Microbiol 2021; 63:189-194. [PMID: 34411806 DOI: 10.1016/j.mib.2021.07.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/14/2021] [Accepted: 07/19/2021] [Indexed: 12/01/2022]
Abstract
Invading microbes occupy the host cytosol and take up nutrients on which host organelles are also dependent. Thus, host organelles are poised to interact with intracellular microbes. Despite the essential role of host mitochondria in cellular metabolic homeostasis and in mediating cellular responses to microbial infection, we know little of how these organelles interact with intracellular pathogens, and how such interactions affect disease pathogenesis. Here, we give an overview of the different classes of physical and metabolic interactions reported to occur between mitochondria and eukaryotic pathogens. Investigating the underlying molecular mechanisms and functions of such interactions will reveal novel aspects of infection biology.
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Affiliation(s)
- Tânia C Medeiros
- Max Planck Institute for Biology of Ageing, 50931, Cologne, Germany
| | - Chahat Mehra
- Max Planck Institute for Biology of Ageing, 50931, Cologne, Germany
| | - Lena Pernas
- Max Planck Institute for Biology of Ageing, 50931, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD), University of Cologne, 50931, Cologne, Germany.
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15
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Kellermann M, Scharte F, Hensel M. Manipulation of Host Cell Organelles by Intracellular Pathogens. Int J Mol Sci 2021; 22:ijms22126484. [PMID: 34204285 PMCID: PMC8235465 DOI: 10.3390/ijms22126484] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 12/13/2022] Open
Abstract
Pathogenic intracellular bacteria, parasites and viruses have evolved sophisticated mechanisms to manipulate mammalian host cells to serve as niches for persistence and proliferation. The intracellular lifestyles of pathogens involve the manipulation of membrane-bound organellar compartments of host cells. In this review, we described how normal structural organization and cellular functions of endosomes, endoplasmic reticulum, Golgi apparatus, mitochondria, or lipid droplets are targeted by microbial virulence mechanisms. We focus on the specific interactions of Salmonella, Legionella pneumophila, Rickettsia rickettsii, Chlamydia spp. and Mycobacterium tuberculosis representing intracellular bacterial pathogens, and of Plasmodium spp. and Toxoplasma gondii representing intracellular parasites. The replication strategies of various viruses, i.e., Influenza A virus, Poliovirus, Brome mosaic virus, Epstein-Barr Virus, Hepatitis C virus, severe acute respiratory syndrome virus (SARS), Dengue virus, Zika virus, and others are presented with focus on the specific manipulation of the organelle compartments. We compare the specific features of intracellular lifestyle and replication cycles, and highlight the communalities in mechanisms of manipulation deployed.
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Affiliation(s)
- Malte Kellermann
- Abt. Mikrobiologie, Fachbereich Biologie/Chemie, Barbarastr 11, Universität Osnabrück, 49076 Osnabrück, Germany; (M.K.); (F.S.)
| | - Felix Scharte
- Abt. Mikrobiologie, Fachbereich Biologie/Chemie, Barbarastr 11, Universität Osnabrück, 49076 Osnabrück, Germany; (M.K.); (F.S.)
| | - Michael Hensel
- Abt. Mikrobiologie, Fachbereich Biologie/Chemie, Barbarastr 11, Universität Osnabrück, 49076 Osnabrück, Germany; (M.K.); (F.S.)
- CellNanOs–Center of Cellular Nanoanalytics Osnabrück, Universität Osnabrück, Barbarastr 11, 49076 Osnabrück, Germany
- Correspondence: ; Tel.: +49-(0)-541-969-3940
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16
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Xia J, Venkat A, Bainbridge RE, Reese ML, Le Roch KG, Ay F, Boyle JP. Third-generation sequencing revises the molecular karyotype for Toxoplasma gondii and identifies emerging copy number variants in sexual recombinants. Genome Res 2021; 31:834-851. [PMID: 33906962 PMCID: PMC8092015 DOI: 10.1101/gr.262816.120] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 02/03/2021] [Indexed: 12/28/2022]
Abstract
Toxoplasma gondii is a useful model for intracellular parasitism given its ease of culture in the laboratory and genomic resources. However, as for many other eukaryotes, the T. gondii genome contains hundreds of sequence gaps owing to repetitive and/or unclonable sequences that disrupt the assembly process. Here, we use the Oxford Nanopore Minion platform to generate near-complete de novo genome assemblies for multiple strains of T. gondii and its near relative, N. caninum. We significantly improved T. gondii genome contiguity (average N50 of ∼6.6 Mb) and added ∼2 Mb of newly assembled sequence. For all of the T. gondii strains that we sequenced (RH, ME49, CTG, II×III progeny clones CL13, S27, S21, S26, and D3X1), the largest contig ranged in size between 11.9 and 12.1 Mb in size, which is larger than any previously reported T. gondii chromosome, and found to be due to a consistent fusion of Chromosomes VIIb and VIII. These data were validated by mapping existing T. gondii ME49 Hi-C data to our assembly, providing parallel lines of evidence that the T. gondii karyotype consists of 13, rather than 14, chromosomes. By using this technology, we also resolved hundreds of tandem repeats of varying lengths, including in well-known host-targeting effector loci like rhoptry protein 5 (ROP5) and ROP38. Finally, when we compared T. gondii with N. caninum, we found that although the 13-chromosome karyotype was conserved, extensive, previously unappreciated chromosome-scale rearrangements had occurred in T. gondii and N. caninum since their most recent common ancestry.
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Affiliation(s)
- Jing Xia
- Department of Biological Sciences, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Aarthi Venkat
- Computational Biology and Bioinformatics, Yale University, New Haven, Connecticut 06520, USA.,La Jolla Institute for Immunology, La Jolla, California 92037, USA
| | - Rachel E Bainbridge
- Department of Biological Sciences, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | | | - Karine G Le Roch
- Department of Molecular, Cell and Systems Biology, College of Agricultural and Life Sciences, University of California-Riverside, Riverside, California 92521, USA
| | - Ferhat Ay
- La Jolla Institute for Immunology, La Jolla, California 92037, USA.,School of Medicine, University of California-San Diego, La Jolla, California 92093, USA
| | - Jon P Boyle
- Department of Biological Sciences, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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17
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Kochanowsky JA, Thomas KK, Koshy AA. ROP16-Mediated Activation of STAT6 Suppresses Host Cell Reactive Oxygen Species Production, Facilitating Type III Toxoplasma gondii Growth and Survival. mBio 2021; 12:e03305-20. [PMID: 33653884 PMCID: PMC8092286 DOI: 10.1128/mbio.03305-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/22/2021] [Indexed: 12/21/2022] Open
Abstract
Polymorphic effector proteins determine the susceptibility of Toxoplasma gondii strains to IFN-γ-mediated clearance mechanisms deployed by murine host cells. However, less is known about the influence of these polymorphic effector proteins on IFN-γ-independent clearance mechanisms. Here, we show that deletion of one such polymorphic effector protein, ROP16, from a type III background leads to a defect in parasite growth and survival in unstimulated human fibroblasts and murine macrophages. Rescue of these defects requires a ROP16 with a functional kinase domain and the ability to activate a specific family of host cell transcription factors (STAT3, 5a, and 6). The growth and survival defects correlate with an accumulation of host cell reactive oxygen species (ROS) and are prevented by treatment with an ROS inhibitor. Exogenous activation of STAT3 and 6 suppresses host cell ROS production during infection with ROP16-deficient parasites and depletion of STAT6, but not STAT3 or 5a, causes an accumulation of ROS in cells infected with wild-type parasites. Pharmacological inhibition of NOX2 and mitochondrially derived ROS also rescues growth and survival of ROP16-deficient parasites. Collectively, these findings reveal an IFN-γ-independent mechanism of parasite restriction in human cells that is subverted by injection of ROP16 by type III parasites.IMPORTANCEToxoplasma gondii is an obligate intracellular parasite that infects up to one-third of the world's population. Control of the parasite is largely accomplished by IFN-γ-dependent mechanisms that stimulate innate and adaptive immune responses. Parasite suppression of IFN-γ-stimulated responses has been linked to proteins that the parasite secretes into its host cell. These secreted proteins vary by T. gondii strain and determine strain-specific lethality in mice. How these strain-specific polymorphic effector proteins affect IFN-γ-independent parasite control mechanisms in human and murine cells is not well known. This study shows that one such secreted protein, ROP16, enables efficient parasite growth and survival by suppressing IFN-γ-independent production of ROS by human and mouse cells.
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Affiliation(s)
| | | | - Anita A Koshy
- Department of Immunobiology, University of Arizona, Tucson, Arizona, USA
- BIO5 Institute, University of Arizona, Tucson, Arizona, USA
- Department of Neurology, University of Arizona, Tucson, Arizona, USA
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18
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Panas MW, Boothroyd JC. Seizing control: How dense granule effector proteins enable Toxoplasma to take charge. Mol Microbiol 2021; 115:466-477. [PMID: 33400323 PMCID: PMC8344355 DOI: 10.1111/mmi.14679] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/02/2021] [Accepted: 01/03/2021] [Indexed: 12/24/2022]
Abstract
Control of the host cell is crucial to the Apicomplexan parasite, Toxoplasma gondii, while it grows intracellularly. To achieve this goal, these single-celled eukaryotes export a series of effector proteins from organelles known as "dense granules" that interfere with normal cellular processes and responses to invasion. While some effectors are found attached to the outer surface of the parasitophorous vacuole (PV) in which Toxoplasma tachyzoites reside, others are found in the host cell's cytoplasm and yet others make their way into the host nucleus, where they alter host transcription. Among the processes that are severely altered are innate immune responses, host cell cycle, and association with host organelles. The ways in which these crucial processes are altered through the coordinated action of a large collection of effectors is as elegant as it is complex, and is the central focus of the following review; we also discuss the recent advances in our understanding of how dense granule effector proteins are trafficked out of the PV.
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Affiliation(s)
- Michael W. Panas
- Dept. Microbiology and Immunology, Stanford University School of Medicine, Stanford CA 94305
| | - John C. Boothroyd
- Dept. Microbiology and Immunology, Stanford University School of Medicine, Stanford CA 94305
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Effector variation at tandem gene arrays in tissue-dwelling coccidia: who needs antigenic variation anyway? Curr Opin Microbiol 2018; 46:86-92. [PMID: 30317151 DOI: 10.1016/j.mib.2018.09.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 08/28/2018] [Accepted: 09/24/2018] [Indexed: 11/20/2022]
Abstract
Locus expansion and diversification is pervasive in apicomplexan genomes and is predominantly found in loci encoding secreted proteins that interact with factors outside of the parasite. Key for understanding the impact of each of these loci on the host requires identification and functional characterization of their protein products, but these repetitive loci often are refractory to genome assembly. In this review we focus on Toxoplasma gondii and its nearest relatives to highlight the known impact of duplicated and diversified loci on our understanding of the host-pathogen molecular arms race. We describe current tools used for the identification and characterization of these loci, and review the most recent examples of how gene-expansion driven diversification can lead to novel gene functions.
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