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Bondarenko K, Limoge F, Pedram K, Gissot M, Young JC. Enzymatically enhanced ultrastructure expansion microscopy unlocks expansion of in vitro Toxoplasma gondii cysts. mSphere 2024; 9:e0032224. [PMID: 39189782 PMCID: PMC11423595 DOI: 10.1128/msphere.00322-24] [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: 04/24/2024] [Accepted: 07/16/2024] [Indexed: 08/28/2024] Open
Abstract
Expansion microscopy (ExM) is an innovative approach to achieve super-resolution images without using super-resolution microscopes, based on the physical expansion of the sample. The advent of ExM has unlocked the detail of super-resolution images for a broader scientific circle, lowering the cost and entry skill requirements for the field. One of its branches, ultrastructure expansion microscopy (U-ExM), has become popular among research groups studying apicomplexan parasites, including the acute stage of Toxoplasma gondii infection. Here, we show that the chronic cyst-forming stage of Toxoplasma, however, resists U-ExM expansion, impeding precise protein localization. We then solve the in vitro cyst's resistance to denaturation required for successful U-ExM. As the cyst's main structural protein CST1 contains a mucin domain, we added an enzymatic digestion step using the pan-mucinase StcE prior to the expansion protocol. This allowed full expansion of the cysts in fibroblasts and primary neuronal cell culture without disrupting immunofluorescence analysis of parasite proteins. Using StcE-enhanced U-ExM, we clarified the localization of the GRA2 protein, which is important for establishing a normal cyst, observing GRA2 granules spanning across the CST1 cyst wall. The StcE-U-ExM protocol allows accurate pinpointing of proteins in the bradyzoite cyst, which will greatly facilitate investigation of the underlying biology of cyst formation and its vulnerabilities. IMPORTANCE Toxoplasma gondii is an intracellular parasite capable of establishing long-term chronic infection in nearly all warm-blooded animals. During the chronic stage, parasites encapsulate to form cysts predominantly in neurons and skeletal muscle. Current anti-Toxoplasma drugs do not eradicate chronic parasites, leaving a reservoir of infection. The cyst is critical for disease transmission and pathology, yet it is harder to study, with the function of many chronic-stage proteins still unknown. Ultrastructure expansion microscopy, a new method to overcome the light microscopy's diffraction limit by physically expanding the sample, allowed in-depth studies of acute Toxoplasma infection. We show that Toxoplasma cysts resist expansion using standard protocol, but an additional enzymatic digestion with the mucinase StcE allows full expansion. This protocol offers new avenues for examining the chronic stage, including precise spatial organization of cyst-specific proteins, linking these locations to morphological structures, and detailed investigations of components of the durable cyst wall.
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Affiliation(s)
- Kseniia Bondarenko
- Institute of Immunology and Infection Research, School of Biological Sciences, Ashworth laboratories, University of Edinburgh, Edinburgh, United Kingdom
| | - Floriane Limoge
- U1019-UMR 9017-CIIL-Center for Infection and Immunity of Lille, University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, Lille, France
| | - Kayvon Pedram
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, USA
| | - Mathieu Gissot
- U1019-UMR 9017-CIIL-Center for Infection and Immunity of Lille, University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, Lille, France
| | - Joanna C. Young
- Institute of Immunology and Infection Research, School of Biological Sciences, Ashworth laboratories, University of Edinburgh, Edinburgh, United Kingdom
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2
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Zarringhalam K, Ye S, Lou J, Rezvani Y, Gubbels MJ. Cell cycle-regulated ApiAP2s and parasite development: the Toxoplasma paradigm. Curr Opin Microbiol 2023; 76:102383. [PMID: 37898053 PMCID: PMC10840917 DOI: 10.1016/j.mib.2023.102383] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 08/11/2023] [Accepted: 08/27/2023] [Indexed: 10/30/2023]
Abstract
The cell division cycle of T. gondii is driven by cyclically expressed ApiAP2 transcription factors (AP2s) that promote gene sets (regulons) associated with specific biological functions. AP2s drive other AP2s, thereby propelling the progressive gene expression waves defining the lytic cycle. AP2s can act as dimers by themselves, in combination with other AP2s (constitutive or cyclical) or in complexes with epigenetic factors. Exit from the cell cycle into either the extracellular state or differentiation into bradyzoites results in major changes in gene expression. Surprisingly, both transitions lead to expression of a shared set of unique AP2s that suggest a shared stress response that, governed by the specific conditions, leads to different outcomes.
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Affiliation(s)
- Kourosh Zarringhalam
- Department of Mathematics, University of Massachusetts Boston, Boston, MA, USA; Center for Personalized Cancer Therapy, University of Massachusetts Boston, Boston, MA, USA.
| | - Sida Ye
- Department of Mathematics, University of Massachusetts Boston, Boston, MA, USA; Center for Personalized Cancer Therapy, University of Massachusetts Boston, Boston, MA, USA
| | - Jingjing Lou
- Department of Biology, Boston College, Chestnut Hill, MA, USA
| | - Yasaman Rezvani
- Department of Mathematics, University of Massachusetts Boston, Boston, MA, USA; Center for Personalized Cancer Therapy, University of Massachusetts Boston, Boston, MA, USA
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3
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Grochow T, Beck B, Rentería-Solís Z, Schares G, Maksimov P, Strube C, Raqué L, Kacza J, Daugschies A, Fietz SA. Reduced neural progenitor cell count and cortical neurogenesis in guinea pigs congenitally infected with Toxoplasma gondii. Commun Biol 2023; 6:1209. [PMID: 38012384 PMCID: PMC10682419 DOI: 10.1038/s42003-023-05576-6] [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: 04/17/2023] [Accepted: 11/13/2023] [Indexed: 11/29/2023] Open
Abstract
Toxoplasma (T.) gondii is an obligate intracellular parasite with a worldwide distribution. Congenital infection can lead to severe pathological alterations in the brain. To examine the effects of toxoplasmosis in the fetal brain, pregnant guinea pigs are infected with T. gondii oocysts on gestation day 23 and dissected 10, 17 and 25 days afterwards. We show the neocortex to represent a target region of T. gondii and the parasite to infect neural progenitor cells (NPCs), neurons and astrocytes in the fetal brain. Importantly, we observe a significant reduction in neuron number at end-neurogenesis and find a marked reduction in NPC count, indicating that impaired neurogenesis underlies the neuronal decrease in infected fetuses. Moreover, we observe focal microglioses to be associated with T. gondii in the fetal brain. Our findings expand the understanding of the pathophysiology of congenital toxoplasmosis, especially contributing to the development of cortical malformations.
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Affiliation(s)
- Thomas Grochow
- Institute of Veterinary Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
- Institute of Parasitology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
| | - Britta Beck
- Institute of Veterinary Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
- Institute of Parasitology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
| | - Zaida Rentería-Solís
- Institute of Parasitology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
| | - Gereon Schares
- National Reference Laboratory for Toxoplasmosis, Institute of Epidemiology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Pavlo Maksimov
- National Reference Laboratory for Toxoplasmosis, Institute of Epidemiology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Christina Strube
- Institute for Parasitology, Centre for Infection Medicine, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Lisa Raqué
- Veterinary practice Raqué, Leipzig, Germany
| | - Johannes Kacza
- BioImaging Core Facility, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
| | - Arwid Daugschies
- Institute of Parasitology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
| | - Simone A Fietz
- Institute of Veterinary Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany.
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4
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Boissavy T, Rotili D, Mouveaux T, Roger E, Aliouat EM, Pierrot C, Valente S, Mai A, Gissot M. Hydroxamate-based compounds are potent inhibitors of Toxoplasma gondii HDAC biological activity. Antimicrob Agents Chemother 2023; 67:e0066123. [PMID: 37850734 PMCID: PMC10648960 DOI: 10.1128/aac.00661-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 08/27/2023] [Indexed: 10/19/2023] Open
Abstract
Toxoplasmosis is a critical health issue for immune-deficient individuals and the offspring of newly infected mothers. It is caused by a unicellular intracellular parasite called Toxoplasma gondii that is found worldwide. Although efficient drugs are commonly used to treat toxoplasmosis, serious adverse events are common. Therefore, new compounds with potent anti-T. gondii activity are needed to provide better suited treatments. We have tested compounds designed to target specifically histone deacetylase enzymes. Among the 55 compounds tested, we identified three compounds showing a concentration of drug required for 50% inhibition (IC50) in the low 100 nM range with a selectivity index of more than 100. These compounds are not only active at inhibiting the growth of the parasite in vitro but also at preventing some of the consequences of the acute disease in vivo. Two of these hydroxamate based compound also induce a hyper-acetylation of the parasite histones while the parasitic acetylated tubulin level remains unchanged. These findings suggest that the enzymes regulating histone acetylation are potent therapeutic targets for the treatment of acute toxoplasmosis.
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Affiliation(s)
- Tom Boissavy
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Dante Rotili
- Dipartimento di Chimica e Tecnologie del Farmaco "Sapienza" Università di Roma, Rome, Italy
| | - Thomas Mouveaux
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Emmanuel Roger
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - El Moukthar Aliouat
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Christine Pierrot
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Sergio Valente
- Dipartimento di Chimica e Tecnologie del Farmaco "Sapienza" Università di Roma, Rome, Italy
| | - Antonello Mai
- Dipartimento di Chimica e Tecnologie del Farmaco "Sapienza" Università di Roma, Rome, Italy
| | - Mathieu Gissot
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
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Sanchez SG, Bassot E, Cerutti A, Mai Nguyen H, Aïda A, Blanchard N, Besteiro S. The apicoplast is important for the viability and persistence of Toxoplasma gondii bradyzoites. Proc Natl Acad Sci U S A 2023; 120:e2309043120. [PMID: 37590416 PMCID: PMC10450435 DOI: 10.1073/pnas.2309043120] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 06/27/2023] [Indexed: 08/19/2023] Open
Abstract
Toxoplasma gondii is responsible for toxoplasmosis, a disease that can be serious when contracted during pregnancy, but can also be a threat for immunocompromised individuals. Acute infection is associated with the tachyzoite form that spreads rapidly within the host. However, under stress conditions, some parasites can differentiate into cyst-forming bradyzoites, residing mainly in the central nervous system, retina and muscle. Because this latent form of the parasite is resistant to all currently available treatments, and is central to persistence and transmission of the parasite, specific therapeutic strategies targeting this developmental stage need to be found. T. gondii contains a plastid of endosymbiotic origin called the apicoplast, which is an appealing drug target because it is essential for tachyzoite viability and contains several key metabolic pathways that are largely absent from the mammalian host. Its function in bradyzoites, however, is unknown. Our objective was thus to study the contribution of the apicoplast to the viability and persistence of bradyzoites during chronic toxoplasmosis. We have used complementary strategies based on stage-specific promoters to generate conditional bradyzoite mutants of essential apicoplast genes. Our results show that specifically targeting the apicoplast in both in vitro or in vivo-differentiated bradyzoites leads to a loss of long-term bradyzoite viability, highlighting the importance of this organelle for this developmental stage. This validates the apicoplast as a potential area to look for therapeutic targets in bradyzoites, with the aim to interfere with this currently incurable parasite stage.
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Affiliation(s)
- Syrian G. Sanchez
- Laboratory of Pathogens and Host Immunity, CNRS, University of Montpellier, 34095Montpellier, France
| | - Emilie Bassot
- Toulouse Institute for Infectious and Inflammatory Diseases, Infinity, University of Toulouse, CNRS, Inserm, Université Paul Sabatier, 31059Toulouse, France
| | - Aude Cerutti
- Laboratory of Pathogens and Host Immunity, CNRS, University of Montpellier, 34095Montpellier, France
| | - Hoa Mai Nguyen
- Laboratory of Pathogens and Host Immunity, CNRS, University of Montpellier, 34095Montpellier, France
| | - Amel Aïda
- Toulouse Institute for Infectious and Inflammatory Diseases, Infinity, University of Toulouse, CNRS, Inserm, Université Paul Sabatier, 31059Toulouse, France
| | - Nicolas Blanchard
- Toulouse Institute for Infectious and Inflammatory Diseases, Infinity, University of Toulouse, CNRS, Inserm, Université Paul Sabatier, 31059Toulouse, France
| | - Sébastien Besteiro
- Laboratory of Pathogens and Host Immunity, CNRS, University of Montpellier, 34095Montpellier, France
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6
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Licon MH, Giuliano CJ, Chan AW, Chakladar S, Eberhard JN, Shallberg LA, Chandrasekaran S, Waldman BS, Koshy AA, Hunter CA, Lourido S. A positive feedback loop controls Toxoplasma chronic differentiation. Nat Microbiol 2023; 8:889-904. [PMID: 37081202 PMCID: PMC10520893 DOI: 10.1038/s41564-023-01358-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 03/07/2023] [Indexed: 04/22/2023]
Abstract
Successful infection strategies must balance pathogen amplification and persistence. In the obligate intracellular parasite Toxoplasma gondii this is accomplished through differentiation into dedicated cyst-forming chronic stages that avoid clearance by the host immune system. The transcription factor BFD1 is both necessary and sufficient for stage conversion; however, its regulation is not understood. In this study we examine five factors that are transcriptionally activated by BFD1. One of these is a cytosolic RNA-binding protein of the CCCH-type zinc-finger family, which we name bradyzoite formation deficient 2 (BFD2). Parasites lacking BFD2 fail to induce BFD1 and are consequently unable to fully differentiate in culture or in mice. BFD2 interacts with the BFD1 transcript under stress, and deletion of BFD2 reduces BFD1 protein levels but not messenger RNA abundance. The reciprocal effects on BFD2 transcription and BFD1 translation outline a positive feedback loop that enforces the chronic-stage gene-expression programme. Thus, our findings help explain how parasites both initiate and commit to chronic differentiation. This work provides new mechanistic insight into the regulation of T. gondii persistence, and can be exploited in the design of strategies to prevent and treat these key reservoirs of human infection.
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Affiliation(s)
| | - Christopher J Giuliano
- Whitehead Institute, Cambridge, MA, USA
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Alex W Chan
- Whitehead Institute, Cambridge, MA, USA
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Sundeep Chakladar
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Julia N Eberhard
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Lindsey A Shallberg
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Benjamin S Waldman
- Whitehead Institute, Cambridge, MA, USA
- Department of Microbiology and Immunology, School of Medicine, Stanford University, Stanford, CA, USA
| | - Anita A Koshy
- BIO5 Institute, University of Arizona, Tucson, AZ, USA
- Department of Neurology, Department of Immunobiology, University of Arizona, Tucson, AZ, USA
| | - Christopher A Hunter
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sebastian Lourido
- Whitehead Institute, Cambridge, MA, USA.
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA, USA.
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7
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Warschkau D, Seeber F. Advances towards the complete in vitro life cycle of Toxoplasma gondii. Fac Rev 2023; 12:1. [PMID: 36846606 PMCID: PMC9944905 DOI: 10.12703/r/12-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
The full life cycle of Toxoplasma gondii cannot be recapitulated in vitro, and access to certain stages, such as mature tissue cysts (bradyzoites) and oocysts (sporozoites), traditionally requires animal experiments. This has greatly hindered the study of the biology of these morphologically and metabolically distinct stages, which are essential for the infection of humans and animals. However, several breakthrough advances have been made in recent years towards obtaining these life stages in vitro, such as the discovery of several molecular factors that induce differentiation and commitment to the sexual cycle, and different culture methods that use, for example, myotubes and intestinal organoids to obtain mature bradyzoites and different sexual stages of the parasite. We review these novel tools and approaches, highlight their limitations and challenges, and discuss what research questions can already be answered with these models. We finally identify future routes for recapitulating the entire sexual cycle in vitro.
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Affiliation(s)
- David Warschkau
- FG16: Mycotic and Parasitic Agents and Mycobacteria, Robert Koch-Institut, Berlin, Germany
| | - Frank Seeber
- FG16: Mycotic and Parasitic Agents and Mycobacteria, Robert Koch-Institut, Berlin, Germany
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8
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Pan M, Ge CC, Fan YM, Jin QW, Shen B, Huang SY. The determinants regulating Toxoplasma gondii bradyzoite development. Front Microbiol 2022; 13:1027073. [PMID: 36439853 PMCID: PMC9691885 DOI: 10.3389/fmicb.2022.1027073] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/24/2022] [Indexed: 11/04/2023] Open
Abstract
Toxoplasma gondii is an obligate intracellular zoonotic pathogen capable of infecting almost all cells of warm-blooded vertebrates. In intermediate hosts, this parasite reproduces asexually in two forms, the tachyzoite form during acute infection that proliferates rapidly and the bradyzoite form during chronic infection that grows slowly. Depending on the growth condition, the two forms can interconvert. The conversion of tachyzoites to bradyzoites is critical for T. gondii transmission, and the reactivation of persistent bradyzoites in intermediate hosts may lead to symptomatic toxoplasmosis. However, the mechanisms that control bradyzoite differentiation have not been well studied. Here, we review recent advances in the study of bradyzoite biology and stage conversion, aiming to highlight the determinants associated with bradyzoite development and provide insights to design better strategies for controlling toxoplasmosis.
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Affiliation(s)
- Ming Pan
- Institute of Comparative Medicine, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Ceng-Ceng Ge
- Institute of Comparative Medicine, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Yi-Min Fan
- Institute of Comparative Medicine, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Qi-Wang Jin
- Institute of Comparative Medicine, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Bang Shen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Si-Yang Huang
- Institute of Comparative Medicine, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, The Ministry of Education of China, Yangzhou University, Yangzhou, China
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9
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Naumov AV, Wang C, Chaput D, Ting LM, Alvarez CA, Keller T, Ramadan A, White MW, Kim K, Suvorova ES. Restriction Checkpoint Controls Bradyzoite Development in Toxoplasma gondii. Microbiol Spectr 2022; 10:e0070222. [PMID: 35652638 PMCID: PMC9241953 DOI: 10.1128/spectrum.00702-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 05/04/2022] [Indexed: 11/21/2022] Open
Abstract
Human toxoplasmosis is a life-threatening disease caused by the apicomplexan parasite Toxoplasma gondii. Rapid replication of the tachyzoite is associated with symptomatic disease, while suppressed division of the bradyzoite is responsible for chronic disease. Here, we identified the T. gondii cell cycle mechanism, the G1 restriction checkpoint (R-point), that operates the switch between parasite growth and differentiation. Apicomplexans lack conventional R-point regulators, suggesting adaptation of alternative factors. We showed that Cdk-related G1 kinase TgCrk2 forms alternative complexes with atypical cyclins (TgCycP1, TgCycP2, and TgCyc5) in the rapidly dividing developmentally incompetent RH and slower dividing developmentally competent ME49 tachyzoites and bradyzoites. Examination of cyclins verified the correlation of cyclin expression with growth dependence and development capacity of RH and ME49 strains. We demonstrated that rapidly dividing RH tachyzoites were dependent on TgCycP1 expression, which interfered with bradyzoite differentiation. Using the conditional knockdown model, we established that TgCycP2 regulated G1 duration in the developmentally competent ME49 tachyzoites but not in the developmentally incompetent RH tachyzoites. We tested the functions of TgCycP2 and TgCyc5 in alkaline induced and spontaneous bradyzoite differentiation (rat embryonic brain cells) models. Based on functional and global gene expression analyses, we determined that TgCycP2 also regulated bradyzoite replication, while signal-induced TgCyc5 was critical for efficient tissue cyst maturation. In conclusion, we identified the central machinery of the T. gondii restriction checkpoint comprised of TgCrk2 kinase and three atypical T. gondii cyclins and demonstrated the independent roles of TgCycP1, TgCycP2, and TgCyc5 in parasite growth and development. IMPORTANCE Toxoplasma gondii is a virulent and abundant human pathogen that puts millions of silently infected people at risk of reactivation of the chronic disease. Encysted bradyzoites formed during the chronic stage are resistant to current therapies. Therefore, insights into the mechanism of tissue cyst formation and reactivation are major areas of investigation. The fact that rapidly dividing parasites differentiate poorly strongly suggests that there is a threshold of replication rate that must be crossed to be considered for differentiation. We discovered a cell cycle mechanism that controls the T. gondii growth-rest switch involved in the conversion of dividing tachyzoites into largely quiescent bradyzoites. This switch operates the T. gondii restriction checkpoint using a set of atypical and parasite-specific regulators. Importantly, the novel T. gondii R-point network was not present in the parasite's human and animal hosts, offering a wealth of new and parasite-specific drug targets to explore in the future.
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Affiliation(s)
- Anatoli V. Naumov
- Department of Internal Medicine, Division of Infectious Diseases and International Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Chengqi Wang
- Center for Global Health and Infectious Diseases Research and USF Genomics Program, College of Public Health, University of South Florida, Tampa, Florida, USA
| | - Dale Chaput
- Proteomics Core, College of Arts and Sciences, University of South Florida, Tampa, Florida, USA
| | - Li-Min Ting
- Department of Internal Medicine, Division of Infectious Diseases and International Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Carmelo A. Alvarez
- Department of Internal Medicine, Division of Infectious Diseases and International Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Thomas Keller
- Department of Internal Medicine, Division of Infectious Diseases and International Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Ahmed Ramadan
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Michael W. White
- Department of Internal Medicine, Division of Infectious Diseases and International Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Kami Kim
- Department of Internal Medicine, Division of Infectious Diseases and International Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Elena S. Suvorova
- Department of Internal Medicine, Division of Infectious Diseases and International Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
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10
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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: 0.5] [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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Christiansen C, Maus D, Hoppenz E, Murillo-León M, Hoffmann T, Scholz J, Melerowicz F, Steinfeldt T, Seeber F, Blume M. In vitro maturation of Toxoplasma gondii bradyzoites in human myotubes and their metabolomic characterization. Nat Commun 2022; 13:1168. [PMID: 35246532 PMCID: PMC8897399 DOI: 10.1038/s41467-022-28730-w] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 02/02/2022] [Indexed: 12/15/2022] Open
Abstract
The apicomplexan parasite Toxoplasma gondii forms bradyzoite-containing tissue cysts that cause chronic and drug-tolerant infections. However, current in vitro models do not allow long-term culture of these cysts to maturity. Here, we developed a human myotube-based in vitro culture model of functionally mature tissue cysts that are orally infectious to mice and tolerate exposure to a range of antibiotics and temperature stresses. Metabolomic characterization of purified cysts reveals global changes that comprise increased levels of amino acids and decreased abundance of nucleobase- and tricarboxylic acid cycle-associated metabolites. In contrast to fast replicating tachyzoite forms of T. gondii these tissue cysts tolerate exposure to the aconitase inhibitor sodium fluoroacetate. Direct access to persistent stages of T. gondii under defined cell culture conditions will be essential for the dissection of functionally important host-parasite interactions and drug evasion mechanisms. It will also facilitate the identification of new strategies for therapeutic intervention. Bradyzoites are a quiescent form of Toxoplasma gondii enclosed in cysts during chronic infections. Here, Christiansen et al. develop a human myotube-based in vitro culture model of cysts that are infectious to mice and characterize their metabolism in comparison to fast replicating tachyzoites.
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Affiliation(s)
- Céline Christiansen
- NG2: Metabolism of Microbial Pathogens, Robert Koch-Institute, 13353, Berlin, Germany
| | - Deborah Maus
- NG2: Metabolism of Microbial Pathogens, Robert Koch-Institute, 13353, Berlin, Germany
| | - Ellen Hoppenz
- NG2: Metabolism of Microbial Pathogens, Robert Koch-Institute, 13353, Berlin, Germany
| | - Mateo Murillo-León
- Institute of Virology, Medical Center University of Freiburg, 79104, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, 79104, Freiburg, Germany.,Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany
| | - Tobias Hoffmann
- ZBS 4: Advanced Light and Electron Microscopy, Centre for Biological Threats and Special Pathogens 4, Robert Koch-Institute, 13353, Berlin, Germany
| | - Jana Scholz
- NG2: Metabolism of Microbial Pathogens, Robert Koch-Institute, 13353, Berlin, Germany
| | - Florian Melerowicz
- NG2: Metabolism of Microbial Pathogens, Robert Koch-Institute, 13353, Berlin, Germany
| | - Tobias Steinfeldt
- Institute of Virology, Medical Center University of Freiburg, 79104, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, 79104, Freiburg, Germany
| | - Frank Seeber
- FG 16: Mycotic and Parasitic Agents and Mycobacteria, Robert Koch-Institute, 13353, Berlin, Germany
| | - Martin Blume
- NG2: Metabolism of Microbial Pathogens, Robert Koch-Institute, 13353, Berlin, Germany.
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A potent HDAC inhibitor blocks Toxoplasma gondii tachyzoite growth and profoundly disrupts parasite gene expression. Int J Antimicrob Agents 2022; 59:106526. [PMID: 35041939 DOI: 10.1016/j.ijantimicag.2022.106526] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 12/22/2021] [Accepted: 01/08/2022] [Indexed: 11/23/2022]
Abstract
Toxoplasmosis is a major health issue worldwide especially for immune-deficient individuals and the offspring of newly infected mothers. It is caused by a unicellular intracellular parasite called Toxoplasma gondii. Although the drugs commonly used to treat toxoplasmosis are efficient, they present serious side effects and adverse events are common. Therefore, there is a need for the discovery of new compounds with potent anti-T. gondii activity. We have tested compounds designed to target enzymes that are involved in the epigenetic regulation of gene expression. Among the most active compounds, we identified an HDAC inhibitor that shows an IC50 of around 30 nM with a selectivity index of more than 100. MC1742 is active at inhibiting the growth of the parasite in vitro but also at preventing the consequences of the acute disease in vivo. This compound induces hyper-acetylation of histones while acetylated tubulin level remains unchanged. After MC1742 treatment, the parasite expression profile is profoundly changed with the activation of genes preferentially expressed in the sexual stages that are normally repressed at the tachyzoite stage. These findings suggest that this compound disturbs the T. gondii gene expression program, inducing parasite death.
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Abstract
Toxoplasma gondii is a parasitic protist infecting a wide group of warm-blooded animals, ranging from birds to humans. While this infection is usually asymptomatic in healthy individuals, it can also lead to severe ocular or neurological outcomes in immunocompromised individuals or in developing fetuses. This obligate intracellular parasite has the ability to infect a considerable range of nucleated cells and can propagate in the intermediate host. Yet, under the pressure of the immune system it transforms into an encysted persistent form residing primarily in the brain and muscle tissues. Encysted parasites, which are resistant to current medication, may reactivate and give rise to an acute infection. The clinical outcome of toxoplasmosis depends on a complex balance between the host immune response and parasite virulence factors. Susceptibility to the disease is thus determined by both parasite strains and host species. Recent advances on our understanding of host cell-parasite interactions and parasite virulence have brought new insights into the pathophysiology of T. gondii infection and are summarized here.
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