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Pinzan CF, Sardinha-Silva A, Almeida F, Lai L, Lopes CD, Lourenço EV, Panunto-Castelo A, Matthews S, Roque-Barreira MC. Vaccination with Recombinant Microneme Proteins Confers Protection against Experimental Toxoplasmosis in Mice. PLoS One 2015; 10:e0143087. [PMID: 26575028 PMCID: PMC4648487 DOI: 10.1371/journal.pone.0143087] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 10/04/2015] [Indexed: 12/24/2022] Open
Abstract
Toxoplasmosis, a zoonotic disease caused by Toxoplasma gondii, is an important public health problem and veterinary concern. Although there is no vaccine for human toxoplasmosis, many attempts have been made to develop one. Promising vaccine candidates utilize proteins, or their genes, from microneme organelle of T. gondii that are involved in the initial stages of host cell invasion by the parasite. In the present study, we used different recombinant microneme proteins (TgMIC1, TgMIC4, or TgMIC6) or combinations of these proteins (TgMIC1-4 and TgMIC1-4-6) to evaluate the immune response and protection against experimental toxoplasmosis in C57BL/6 mice. Vaccination with recombinant TgMIC1, TgMIC4, or TgMIC6 alone conferred partial protection, as demonstrated by reduced brain cyst burden and mortality rates after challenge. Immunization with TgMIC1-4 or TgMIC1-4-6 vaccines provided the most effective protection, since 70% and 80% of mice, respectively, survived to the acute phase of infection. In addition, these vaccinated mice, in comparison to non-vaccinated ones, showed reduced parasite burden by 59% and 68%, respectively. The protective effect was related to the cellular and humoral immune responses induced by vaccination and included the release of Th1 cytokines IFN-γ and IL-12, antigen-stimulated spleen cell proliferation, and production of antigen-specific serum antibodies. Our results demonstrate that microneme proteins are potential vaccines against T. gondii, since their inoculation prevents or decreases the deleterious effects of the infection.
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Affiliation(s)
- Camila Figueiredo Pinzan
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Aline Sardinha-Silva
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Fausto Almeida
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Livia Lai
- Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom
| | - Carla Duque Lopes
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Elaine Vicente Lourenço
- Department of Medicine, Division of Rheumatology, University of California Los Angeles, Los Angeles, California, 90095–1670, United States of America
| | - Ademilson Panunto-Castelo
- Department of Biology, School of Philosophy, Sciences and Literature of Ribeirão Preto, University of Sao Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Stephen Matthews
- Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom
| | - Maria Cristina Roque-Barreira
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
- * E-mail:
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52
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Abstract
Toxoplasmosis is the clinical and pathological consequence of acute infection with the obligate intracellular apicomplexan parasite Toxoplasma gondii. Symptoms result from tissue destruction that accompanies lytic parasite growth. This review updates current understanding of the host cell invasion, parasite replication, and eventual egress that constitute the lytic cycle, as well as the ways T. gondii manipulates host cells to ensure its survival. Since the publication of a previous iteration of this review 15 years ago, important advances have been made in our molecular understanding of parasite growth and mechanisms of host cell egress, and knowledge of the parasite's manipulation of the host has rapidly progressed. Here we cover molecular advances and current conceptual frameworks that include each of these topics, with an eye to what may be known 15 years from now.
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Affiliation(s)
- Ira J Blader
- Department of Microbiology and Immunology, University at Buffalo, Buffalo, New York 14127;
| | - Bradley I Coleman
- Department of Biology, Boston College, Chestnut Hill, Massachusetts 02467; , ,
| | - Chun-Ti Chen
- Department of Biology, Boston College, Chestnut Hill, Massachusetts 02467; , ,
| | - Marc-Jan Gubbels
- Department of Biology, Boston College, Chestnut Hill, Massachusetts 02467; , ,
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53
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Paul AS, Saha S, Engelberg K, Jiang RHY, Coleman BI, Kosber AL, Chen CT, Ganter M, Espy N, Gilberger TW, Gubbels MJ, Duraisingh MT. Parasite Calcineurin Regulates Host Cell Recognition and Attachment by Apicomplexans. Cell Host Microbe 2015; 18:49-60. [PMID: 26118996 DOI: 10.1016/j.chom.2015.06.003] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 04/30/2015] [Accepted: 05/28/2015] [Indexed: 12/12/2022]
Abstract
Apicomplexans invade a variety of metazoan host cells through mechanisms involving host cell receptor engagement and secretion of parasite factors to facilitate cellular attachment. We find that the parasite homolog of calcineurin, a calcium-regulated phosphatase complex central to signal transduction in eukaryotes, also contributes to host cell invasion by the malaria parasite Plasmodium falciparum and related Toxoplasma gondii. Using reverse-genetic and chemical-genetic approaches, we determine that calcineurin critically regulates and stabilizes attachment of extracellular P. falciparum to host erythrocytes before intracellular entry and has similar functions in host cell engagement by T. gondii. Calcineurin-mediated Plasmodium invasion is strongly associated with host receptors required for host cell recognition, and calcineurin function distinguishes this form of receptor-mediated attachment from a second mode of host-parasite adhesion independent of host receptors. This specific role of calcineurin in coordinating physical interactions with host cells highlights an ancestral mechanism for parasitism used by apicomplexans.
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Affiliation(s)
- Aditya S Paul
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Sudeshna Saha
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA
| | | | - Rays H Y Jiang
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | | | - Aziz L Kosber
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Chun-Ti Chen
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA
| | - Markus Ganter
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Nicole Espy
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Tim W Gilberger
- Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany; Centre for Structural Systems Biology, 22607 Hamburg, Germany
| | - Marc-Jan Gubbels
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA
| | - Manoj T Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA.
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54
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Rugarabamu G, Marq JB, Guérin A, Lebrun M, Soldati-Favre D. Distinct contribution of Toxoplasma gondii rhomboid proteases 4 and 5 to micronemal protein protease 1 activity during invasion. Mol Microbiol 2015; 97:244-62. [PMID: 25846828 DOI: 10.1111/mmi.13021] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2015] [Indexed: 10/23/2022]
Abstract
Host cell entry by the Apicomplexa is associated with the sequential secretion of invasion factors from specialized apical organelles. Secretion of micronemal proteins (MICs) complexes by Toxoplasma gondii facilitates parasite gliding motility, host cell attachment and entry, as well as egress from infected cells. The shedding of MICs during these steps is mediated by micronemal protein proteases MPP1, MPP2 and MPP3. The constitutive activity of MPP1 leads to the cleavage of transmembrane MICs and is linked to the surface rhomboid protease 4 (ROM4) and possibly to rhomboid protease 5 (ROM5). To determine their importance and respective contribution to MPP1 activity, in this study ROM4 and ROM5 genes were abrogated using Cre-recombinase and CRISPR-Cas9 nuclease, respectively, and shown to be dispensable for parasite survival. Parasites lacking ROM4 predominantly engage in twirling motility and exhibit enhanced attachment and impaired invasion, whereas intracellular growth and egress is not affected. The substrates MIC2 and MIC6 are not cleaved in rom4-ko parasites, in contrast, intramembrane cleavage of AMA1 is reduced but not completely abolished. Shedding of MICs and invasion are not altered in the absence of ROM5; however, this protease responsible for the residual cleavage of AMA1 is able to cleave other AMA family members and exhibits a detectable contribution to invasion in the absence of ROM4.
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Affiliation(s)
- George Rugarabamu
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 Rue Michel-Servet, 1211, Geneva 4, Switzerland
| | - Jean-Baptiste Marq
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 Rue Michel-Servet, 1211, Geneva 4, Switzerland
| | - Amandine Guérin
- UMR 5235 CNRS, Université de Montpellier 2, 34095, Montpellier, France
| | - Maryse Lebrun
- UMR 5235 CNRS, Université de Montpellier 2, 34095, Montpellier, France
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 Rue Michel-Servet, 1211, Geneva 4, Switzerland
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Morlon‐Guyot J, Pastore S, Berry L, Lebrun M, Daher W. Toxoplasma gondii
Vps11, a subunit of
HOPS
and
CORVET
tethering complexes, is essential for the biogenesis of secretory organelles. Cell Microbiol 2015; 17:1157-78. [DOI: 10.1111/cmi.12426] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Revised: 01/20/2015] [Accepted: 01/28/2015] [Indexed: 12/17/2022]
Affiliation(s)
- Juliette Morlon‐Guyot
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS Université Montpellier Montpellier France
| | - Sandra Pastore
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS Université Montpellier Montpellier France
| | - Laurence Berry
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS Université Montpellier Montpellier France
| | - Maryse Lebrun
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS Université Montpellier Montpellier France
| | - Wassim Daher
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS Université Montpellier Montpellier France
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Hehl AB, Basso WU, Lippuner C, Ramakrishnan C, Okoniewski M, Walker RA, Grigg ME, Smith NC, Deplazes P. Asexual expansion of Toxoplasma gondii merozoites is distinct from tachyzoites and entails expression of non-overlapping gene families to attach, invade, and replicate within feline enterocytes. BMC Genomics 2015; 16:66. [PMID: 25757795 PMCID: PMC4340605 DOI: 10.1186/s12864-015-1225-x] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 01/07/2015] [Indexed: 12/21/2022] Open
Abstract
Background The apicomplexan parasite Toxoplasma gondii is cosmopolitan in nature, largely as a result of its highly flexible life cycle. Felids are its only definitive hosts and a wide range of mammals and birds serve as intermediate hosts. The latent bradyzoite stage is orally infectious in all warm-blooded vertebrates and establishes chronic, transmissible infections. When bradyzoites are ingested by felids, they transform into merozoites in enterocytes and expand asexually as part of their coccidian life cycle. In all other intermediate hosts, however, bradyzoites differentiate exclusively to tachyzoites, and disseminate extraintestinally to many cell types. Both merozoites and tachyzoites undergo rapid asexual population expansion, yet possess different effector fates with respect to the cells and tissues they develop in and the subsequent stages they differentiate into. Results To determine whether merozoites utilize distinct suites of genes to attach, invade, and replicate within feline enterocytes, we performed comparative transcriptional profiling on purified tachyzoites and merozoites. We used high-throughput RNA-Seq to compare the merozoite and tachyzoite transcriptomes. 8323 genes were annotated with sequence reads across the two asexually replicating stages of the parasite life cycle. Metabolism was similar between the two replicating stages. However, significant stage-specific expression differences were measured, with 312 transcripts exclusive to merozoites versus 453 exclusive to tachyzoites. Genes coding for 177 predicted secreted proteins and 64 membrane- associated proteins were annotated as merozoite-specific. The vast majority of known dense-granule (GRA), microneme (MIC), and rhoptry (ROP) genes were not expressed in merozoites. In contrast, a large set of surface proteins (SRS) was expressed exclusively in merozoites. Conclusions The distinct expression profiles of merozoites and tachyzoites reveal significant additional complexity within the T. gondii life cycle, demonstrating that merozoites are distinct asexual dividing stages which are uniquely adapted to their niche and biological purpose. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1225-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Adrian B Hehl
- Institute of Parasitology-University of Zurich, Winterthurerstrasse 266a, Zürich, 8057, Switzerland.
| | - Walter U Basso
- Institute of Parasitology-University of Zurich, Winterthurerstrasse 266a, Zürich, 8057, Switzerland.
| | - Christoph Lippuner
- Institute of Parasitology-University of Zurich, Winterthurerstrasse 266a, Zürich, 8057, Switzerland. .,Current address: Department of Anaesthesiology and Pain Medicine, Inselspital, University of Bern, Freiburgstrasse, Bern, 3010, Switzerland.
| | - Chandra Ramakrishnan
- Institute of Parasitology-University of Zurich, Winterthurerstrasse 266a, Zürich, 8057, Switzerland.
| | - Michal Okoniewski
- Functional Genomics Center Zurich, Winterthurerstrasse 190, Zürich, 8057, Switzerland.
| | - Robert A Walker
- Institute of Parasitology-University of Zurich, Winterthurerstrasse 266a, Zürich, 8057, Switzerland. .,Queensland Tropical Health Alliance Research Laboratory, Faculty of Medicine, Health and Molecular Sciences, James Cook University, Cairns Campus, McGregor Road, Smithfield, QLD, 4878, Australia.
| | - Michael E Grigg
- Molecular Parasitology Section, Laboratory of Parasitic Diseases, NIAID, NIH, Bethesda, Maryland, USA.
| | - Nicholas C Smith
- Queensland Tropical Health Alliance Research Laboratory, Faculty of Medicine, Health and Molecular Sciences, James Cook University, Cairns Campus, McGregor Road, Smithfield, QLD, 4878, Australia.
| | - Peter Deplazes
- Institute of Parasitology-University of Zurich, Winterthurerstrasse 266a, Zürich, 8057, Switzerland.
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57
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Lim SSY, Othman RY. Recent advances in Toxoplasma gondii immunotherapeutics. THE KOREAN JOURNAL OF PARASITOLOGY 2014; 52:581-93. [PMID: 25548409 PMCID: PMC4277020 DOI: 10.3347/kjp.2014.52.6.581] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 08/21/2014] [Accepted: 08/22/2014] [Indexed: 12/11/2022]
Abstract
Toxoplasmosis is an opportunistic infection caused by the protozoan parasite Toxoplasma gondii. T. gondii is widespread globally and causes severe diseases in individuals with impaired immune defences as well as congenitally infected infants. The high prevalence rate in some parts of the world such as South America and Africa, coupled with the current drug treatments that trigger hypersensitivity reactions, makes the development of immunotherapeutics intervention a highly important research priority. Immunotherapeutics strategies could either be a vaccine which would confer a pre-emptive immunity to infection, or passive immunization in cases of disease recrudescence or recurrent clinical diseases. As the severity of clinical manifestations is often greater in developing nations, the development of well-tolerated and safe immunotherapeutics becomes not only a scientific pursuit, but a humanitarian enterprise. In the last few years, much progress has been made in vaccine research with new antigens, novel adjuvants, and innovative vaccine delivery such as nanoparticles and antigen encapsulations. A literature search over the past 5 years showed that most experimental studies were focused on DNA vaccination at 52%, followed by protein vaccination which formed 36% of the studies, live attenuated vaccinations at 9%, and heterologous vaccination at 3%; while there were few on passive immunization. Recent progress in studies on vaccination, passive immunization, as well as insights gained from these immunotherapeutics is highlighted in this review.
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Affiliation(s)
- Sherene Swee-Yin Lim
- Genetics and Molecular Biology Department, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Rofina Yasmin Othman
- Genetics and Molecular Biology Department, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia. ; Centre for Research in Biotechnology for Agriculture, University of Malaya, 50603 Kuala Lumpur, Malaysia
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58
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Lee WK, Ahn HJ, Baek JH, Lee CH, Yu YG, Nam HW. Comprehensive Proteome Analysis of the Excretory/Secretory Proteins of Toxoplasma gondii. B KOREAN CHEM SOC 2014. [DOI: 10.5012/bkcs.2014.35.10.3071] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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59
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Bargieri D, Lagal V, Andenmatten N, Tardieux I, Meissner M, Ménard R. Host cell invasion by apicomplexan parasites: the junction conundrum. PLoS Pathog 2014; 10:e1004273. [PMID: 25232721 PMCID: PMC4169498 DOI: 10.1371/journal.ppat.1004273] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Affiliation(s)
- Daniel Bargieri
- Institut Pasteur, Malaria Biology and Genetics Unit, Department of Parasitology and Mycology, Paris, France
| | - Vanessa Lagal
- Institut Cochin, Laboratory Barriers and Pathogens, INSERM U-1016, CNRS UMR-8104, University of Paris Descartes, Paris, France
| | - Nicole Andenmatten
- Institute of Infection, Immunity and Inflammation, Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, United Kingdom
| | - Isabelle Tardieux
- Institut Cochin, Laboratory Barriers and Pathogens, INSERM U-1016, CNRS UMR-8104, University of Paris Descartes, Paris, France
| | - Markus Meissner
- Institute of Infection, Immunity and Inflammation, Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, United Kingdom
| | - Robert Ménard
- Institut Pasteur, Malaria Biology and Genetics Unit, Department of Parasitology and Mycology, Paris, France
- * E-mail:
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60
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A conserved apicomplexan microneme protein contributes to Toxoplasma gondii invasion and virulence. Infect Immun 2014; 82:4358-68. [PMID: 25092910 DOI: 10.1128/iai.01877-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The obligate intracellular parasite Toxoplasma gondii critically relies on host cell invasion during infection. Proteins secreted from the apical micronemes are central components for host cell recognition, invasion, egress, and virulence. Although previous work established that the sporozoite protein with an altered thrombospondin repeat (SPATR) is a micronemal protein conserved in other apicomplexan parasites, including Plasmodium, Neospora, and Eimeria, no genetic evidence of its contribution to invasion has been reported. SPATR contains a predicted epidermal growth factor domain and two thrombospondin type 1 repeats, implying a role in host cell recognition. In this study, we assess the contribution of T. gondii SPATR (TgSPATR) to T. gondii invasion by genetically ablating it and restoring its expression by genetic complementation. Δspatr parasites were ~50% reduced in invasion compared to parental strains, a defect that was reversed in the complemented strain. In mouse virulence assays, Δspatr parasites were significantly attenuated, with ~20% of mice surviving infection. Given the conservation of this protein among the Apicomplexa, we assessed whether the Plasmodium falciparum SPATR ortholog (PfSPATR) could complement the absence of the TgSPATR. Although PfSPATR showed correct micronemal localization, it did not reverse the invasion deficiency of Δspatr parasites, because of an apparent failure in secretion. Overall, the results suggest that TgSPATR contributes to invasion and virulence, findings that have implications for the many genera and life stages of apicomplexans that express SPATR.
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61
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Paing MM, Tolia NH. Multimeric assembly of host-pathogen adhesion complexes involved in apicomplexan invasion. PLoS Pathog 2014; 10:e1004120. [PMID: 24945143 PMCID: PMC4055764 DOI: 10.1371/journal.ppat.1004120] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- May M. Paing
- Department of Molecular Microbiology and Microbial Pathogenesis, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Niraj H. Tolia
- Department of Molecular Microbiology and Microbial Pathogenesis, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- * E-mail:
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62
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The apical complex provides a regulated gateway for secretion of invasion factors in Toxoplasma. PLoS Pathog 2014; 10:e1004074. [PMID: 24743791 PMCID: PMC3990729 DOI: 10.1371/journal.ppat.1004074] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2013] [Accepted: 03/04/2014] [Indexed: 11/19/2022] Open
Abstract
The apical complex is the definitive cell structure of phylum Apicomplexa, and is the focus of the events of host cell penetration and the establishment of intracellular parasitism. Despite the importance of this structure, its molecular composition is relatively poorly known and few studies have experimentally tested its functions. We have characterized a novel Toxoplasma gondii protein, RNG2, that is located at the apical polar ring--the common structural element of apical complexes. During cell division, RNG2 is first recruited to centrosomes immediately after their duplication, confirming that assembly of the new apical complex commences as one of the earliest events of cell replication. RNG2 subsequently forms a ring, with the carboxy- and amino-termini anchored to the apical polar ring and mobile conoid, respectively, linking these two structures. Super-resolution microscopy resolves these two termini, and reveals that RNG2 orientation flips during invasion when the conoid is extruded. Inducible knockdown of RNG2 strongly inhibits host cell invasion. Consistent with this, secretion of micronemes is prevented in the absence of RNG2. This block, however, can be fully or partially overcome by exogenous stimulation of calcium or cGMP signaling pathways, respectively, implicating the apical complex directly in these signaling events. RNG2 demonstrates for the first time a role for the apical complex in controlling secretion of invasion factors in this important group of parasites.
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63
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Egarter S, Andenmatten N, Jackson AJ, Whitelaw JA, Pall G, Black JA, Ferguson DJP, Tardieux I, Mogilner A, Meissner M. The toxoplasma Acto-MyoA motor complex is important but not essential for gliding motility and host cell invasion. PLoS One 2014; 9:e91819. [PMID: 24632839 PMCID: PMC3954763 DOI: 10.1371/journal.pone.0091819] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 02/13/2014] [Indexed: 12/23/2022] Open
Abstract
Apicomplexan parasites are thought to actively invade the host cell by gliding motility. This movement is powered by the parasite's own actomyosin system, and depends on the regulated polymerisation and depolymerisation of actin to generate the force for gliding and host cell penetration. Recent studies demonstrated that Toxoplasma gondii can invade the host cell in the absence of several core components of the invasion machinery, such as the motor protein myosin A (MyoA), the microneme proteins MIC2 and AMA1 and actin, indicating the presence of alternative invasion mechanisms. Here the roles of MyoA, MLC1, GAP45 and Act1, core components of the gliding machinery, are re-dissected in detail. Although important roles of these components for gliding motility and host cell invasion are verified, mutant parasites remain invasive and do not show a block of gliding motility, suggesting that other mechanisms must be in place to enable the parasite to move and invade the host cell. A novel, hypothetical model for parasite gliding motility and invasion is presented based on osmotic forces generated in the cytosol of the parasite that are converted into motility.
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Affiliation(s)
- Saskia Egarter
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Nicole Andenmatten
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Allison J. Jackson
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Jamie A. Whitelaw
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Gurman Pall
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Jennifer Ann Black
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - David J. P. Ferguson
- Nuffield Department of Clinical Laboratory Science, Oxford University, Oxford, United Kingdom
| | - Isabelle Tardieux
- Institut Cochin, University of Paris Descartes, INSERM U-1016, CNRS UMR-8104, Paris, France
| | - Alex Mogilner
- Department of Neurobiology, Physiology, and Behavior and Department of Mathematics, University of California Davis, Davis, California, United States of America
| | - Markus Meissner
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- * E-mail:
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64
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Chapman HD, Barta JR, Blake D, Gruber A, Jenkins M, Smith NC, Suo X, Tomley FM. A selective review of advances in coccidiosis research. ADVANCES IN PARASITOLOGY 2014; 83:93-171. [PMID: 23876872 DOI: 10.1016/b978-0-12-407705-8.00002-1] [Citation(s) in RCA: 181] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Coccidiosis is a widespread and economically significant disease of livestock caused by protozoan parasites of the genus Eimeria. This disease is worldwide in occurrence and costs the animal agricultural industry many millions of dollars to control. In recent years, the modern tools of molecular biology, biochemistry, cell biology and immunology have been used to expand greatly our knowledge of these parasites and the disease they cause. Such studies are essential if we are to develop new means for the control of coccidiosis. In this chapter, selective aspects of the biology of these organisms, with emphasis on recent research in poultry, are reviewed. Topics considered include taxonomy, systematics, genetics, genomics, transcriptomics, proteomics, transfection, oocyst biogenesis, host cell invasion, immunobiology, diagnostics and control.
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Affiliation(s)
- H David Chapman
- Department of Poultry Science, University of Arkansas, Fayetteville, Arkansas, USA.
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Muniz-Feliciano L, Van Grol J, Portillo JAC, Liew L, Liu B, Carlin CR, Carruthers VB, Matthews S, Subauste CS. Toxoplasma gondii-induced activation of EGFR prevents autophagy protein-mediated killing of the parasite. PLoS Pathog 2013; 9:e1003809. [PMID: 24367261 PMCID: PMC3868508 DOI: 10.1371/journal.ppat.1003809] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 10/19/2013] [Indexed: 12/24/2022] Open
Abstract
Toxoplasma gondii resides in an intracellular compartment (parasitophorous vacuole) that excludes transmembrane molecules required for endosome-lysosome recruitment. Thus, the parasite survives by avoiding lysosomal degradation. However, autophagy can re-route the parasitophorous vacuole to the lysosomes and cause parasite killing. This raises the possibility that T. gondii may deploy a strategy to prevent autophagic targeting to maintain the non-fusogenic nature of the vacuole. We report that T. gondii activated EGFR in endothelial cells, retinal pigment epithelial cells and microglia. Blockade of EGFR or its downstream molecule, Akt, caused targeting of the parasite by LC3(+) structures, vacuole-lysosomal fusion, lysosomal degradation and killing of the parasite that were dependent on the autophagy proteins Atg7 and Beclin 1. Disassembly of GPCR or inhibition of metalloproteinases did not prevent EGFR-Akt activation. T. gondii micronemal proteins (MICs) containing EGF domains (EGF-MICs; MIC3 and MIC6) appeared to promote EGFR activation. Parasites defective in EGF-MICs (MIC1 ko, deficient in MIC1 and secretion of MIC6; MIC3 ko, deficient in MIC3; and MIC1-3 ko, deficient in MIC1, MIC3 and secretion of MIC6) caused impaired EGFR-Akt activation and recombinant EGF-MICs (MIC3 and MIC6) caused EGFR-Akt activation. In cells treated with autophagy stimulators (CD154, rapamycin) EGFR signaling inhibited LC3 accumulation around the parasite. Moreover, increased LC3 accumulation and parasite killing were noted in CD154-activated cells infected with MIC1-3 ko parasites. Finally, recombinant MIC3 and MIC6 inhibited parasite killing triggered by CD154 particularly against MIC1-3 ko parasites. Thus, our findings identified EGFR activation as a strategy used by T. gondii to maintain the non-fusogenic nature of the parasitophorous vacuole and suggest that EGF-MICs have a novel role in affecting signaling in host cells to promote parasite survival.
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Affiliation(s)
- Luis Muniz-Feliciano
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Jennifer Van Grol
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Jose-Andres C. Portillo
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Lloyd Liew
- Division of Molecular Biosciences, Imperial College London, London, United Kingdom
| | - Bing Liu
- Division of Molecular Biosciences, Imperial College London, London, United Kingdom
| | - Cathleen R. Carlin
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Stephen Matthews
- Division of Molecular Biosciences, Imperial College London, London, United Kingdom
| | - Carlos S. Subauste
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America
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Pollo-Oliveira L, Post H, Acencio ML, Lemke N, van den Toorn H, Tragante V, Heck AJR, Altelaar AFM, Yatsuda AP. Unravelling the Neospora caninum secretome through the secreted fraction (ESA) and quantification of the discharged tachyzoite using high-resolution mass spectrometry-based proteomics. Parasit Vectors 2013; 6:335. [PMID: 24267406 PMCID: PMC4182915 DOI: 10.1186/1756-3305-6-335] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 11/15/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The apicomplexan parasite Neospora caninum causes neosporosis, a disease that leads to abortion or stillbirth in cattle, generating an economic impact on the dairy and beef cattle trade. As an obligatory intracellular parasite, N. caninum needs to invade the host cell in an active manner to survive. The increase in parasite cytosolic Ca2+ upon contact with the host cell mediates critical events, including the exocytosis of phylum-specific secretory organelles and the activation of the parasite invasion motor. Because invasion is considered a requirement for pathogen survival and replication within the host, the identification of secreted proteins (secretome) involved in invasion may be useful to reveal interesting targets for therapeutic intervention. METHODS To chart the currently missing N. caninum secretome, we employed mass spectrometry-based proteomics to identify proteins present in the N. caninum tachyzoite using two different approaches. The first approach was identifying the proteins present in the tachyzoite-secreted fraction (ESA). The second approach was determining the relative quantification through peptide stable isotope labelling of the tachyzoites submitted to an ethanol secretion stimulus (discharged tachyzoite), expecting to identify the secreted proteins among the down-regulated group. RESULTS As a result, 615 proteins were identified at ESA and 2,011 proteins quantified at the discharged tachyzoite. We have analysed the connection between the secreted and the down-regulated proteins and searched for putative regulators of the secretion process among the up-regulated proteins. An interaction network was built by computational prediction involving the up- and down-regulated proteins. The mass spectrometry proteomics data have been deposited to the ProteomeXchange with identifier PXD000424. CONCLUSIONS The comparison between the protein abundances in ESA and their measure in the discharged tachyzoite allowed for a more precise identification of the most likely secreted proteins. Information from the network interaction and up-regulated proteins was important to recognise key proteins potentially involved in the metabolic regulation of secretion. Our results may be helpful to guide the selection of targets to be investigated against Neospora caninum and other Apicomplexan organisms.
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Affiliation(s)
- Letícia Pollo-Oliveira
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto e Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos (NPPNS), Universidade de São Paulo, Av do Café , s/n, Ribeirão Preto, SP 14040-903, Brazil
| | - Harm Post
- Biomolecular Mass Spectrometry and Proteomics, Utrecht Institute for Pharmaceutical Sciences and Bijvoet Centre for Biomolecular Research, Utrecht University, Padualaan 8, Utrecht 3884 CH, The Netherlands
- Netherlands Proteomics Centre, Padualaan 8, Utrecht 3884 CH, The Netherlands
| | - Marcio Luis Acencio
- Botucatu Institute of Biosciences, UNESP - Univ Estadual Paulista, Distrito de Rubião Jr, s/n, Botucatu, São Paulo 18918-970, Brazil
| | - Ney Lemke
- Botucatu Institute of Biosciences, UNESP - Univ Estadual Paulista, Distrito de Rubião Jr, s/n, Botucatu, São Paulo 18918-970, Brazil
| | - Henk van den Toorn
- Biomolecular Mass Spectrometry and Proteomics, Utrecht Institute for Pharmaceutical Sciences and Bijvoet Centre for Biomolecular Research, Utrecht University, Padualaan 8, Utrecht 3884 CH, The Netherlands
- Netherlands Proteomics Centre, Padualaan 8, Utrecht 3884 CH, The Netherlands
| | - Vinicius Tragante
- Division of Heart and Lungs, Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
- Division of Biomedical Genetics, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Albert JR Heck
- Biomolecular Mass Spectrometry and Proteomics, Utrecht Institute for Pharmaceutical Sciences and Bijvoet Centre for Biomolecular Research, Utrecht University, Padualaan 8, Utrecht 3884 CH, The Netherlands
- Netherlands Proteomics Centre, Padualaan 8, Utrecht 3884 CH, The Netherlands
| | - AF Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Utrecht Institute for Pharmaceutical Sciences and Bijvoet Centre for Biomolecular Research, Utrecht University, Padualaan 8, Utrecht 3884 CH, The Netherlands
- Netherlands Proteomics Centre, Padualaan 8, Utrecht 3884 CH, The Netherlands
| | - Ana Patrícia Yatsuda
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto e Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos (NPPNS), Universidade de São Paulo, Av do Café , s/n, Ribeirão Preto, SP 14040-903, Brazil
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Walker DM, Oghumu S, Gupta G, McGwire BS, Drew ME, Satoskar AR. Mechanisms of cellular invasion by intracellular parasites. Cell Mol Life Sci 2013; 71:1245-63. [PMID: 24221133 DOI: 10.1007/s00018-013-1491-1] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 10/04/2013] [Accepted: 10/07/2013] [Indexed: 12/22/2022]
Abstract
Numerous disease-causing parasites must invade host cells in order to prosper. Collectively, such pathogens are responsible for a staggering amount of human sickness and death throughout the world. Leishmaniasis, Chagas disease, toxoplasmosis, and malaria are neglected diseases and therefore are linked to socio-economical and geographical factors, affecting well-over half the world's population. Such obligate intracellular parasites have co-evolved with humans to establish a complexity of specific molecular parasite-host cell interactions, forming the basis of the parasite's cellular tropism. They make use of such interactions to invade host cells as a means to migrate through various tissues, to evade the host immune system, and to undergo intracellular replication. These cellular migration and invasion events are absolutely essential for the completion of the lifecycles of these parasites and lead to their for disease pathogenesis. This review is an overview of the molecular mechanisms of protozoan parasite invasion of host cells and discussion of therapeutic strategies, which could be developed by targeting these invasion pathways. Specifically, we focus on four species of protozoan parasites Leishmania, Trypanosoma cruzi, Plasmodium, and Toxoplasma, which are responsible for significant morbidity and mortality.
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Affiliation(s)
- Dawn M Walker
- Department of Microbial Infection and Immunity, Wexner Medical Center, The Ohio State University, Columbus, OH, 43210, USA
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68
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Invasion factors of apicomplexan parasites: essential or redundant? Curr Opin Microbiol 2013; 16:438-44. [DOI: 10.1016/j.mib.2013.05.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 04/25/2013] [Accepted: 05/05/2013] [Indexed: 02/03/2023]
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69
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Sharma P, Chitnis CE. Key molecular events during host cell invasion by Apicomplexan pathogens. Curr Opin Microbiol 2013; 16:432-7. [PMID: 23895827 DOI: 10.1016/j.mib.2013.07.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/03/2013] [Accepted: 07/04/2013] [Indexed: 10/26/2022]
Abstract
The ability of Apicomplexan parasites to invade host cells is key to their survival and pathogenesis. Plasmodium and Toxoplasma parasites share common mechanisms for invasion of host cells. Secretion of microneme and rhoptry proteins, tight junction formation and assembly of an acto-myosin motor are key steps for successful invasion by both parasites. Here, we review our understanding of the molecular basis for these steps.
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70
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Kremer K, Kamin D, Rittweger E, Wilkes J, Flammer H, Mahler S, Heng J, Tonkin CJ, Langsley G, Hell SW, Carruthers VB, Ferguson DJP, Meissner M. An overexpression screen of Toxoplasma gondii Rab-GTPases reveals distinct transport routes to the micronemes. PLoS Pathog 2013; 9:e1003213. [PMID: 23505371 PMCID: PMC3591302 DOI: 10.1371/journal.ppat.1003213] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 01/10/2013] [Indexed: 12/20/2022] Open
Abstract
The basic organisation of the endomembrane system is conserved in all eukaryotes and comparative genome analyses provides compelling evidence that the endomembrane system of the last common eukaryotic ancestor (LCEA) is complex with many genes required for regulated traffic being present. Although apicomplexan parasites, causative agents of severe human and animal diseases, appear to have only a basic set of trafficking factors such as Rab-GTPases, they evolved unique secretory organelles (micronemes, rhoptries and dense granules) that are sequentially secreted during invasion of the host cell. In order to define the secretory pathway of apicomplexans, we performed an overexpression screen of Rabs in Toxoplasma gondii and identified Rab5A and Rab5C as important regulators of traffic to micronemes and rhoptries. Intriguingly, we found that not all microneme proteins traffic depends on functional Rab5A and Rab5C, indicating the existence of redundant microneme targeting pathways. Using two-colour super-resolution stimulated emission depletion (STED) we verified distinct localisations of independent microneme proteins and demonstrate that micronemal organelles are organised in distinct subsets or subcompartments. Our results suggest that apicomplexan parasites modify classical regulators of the endocytic system to carryout essential parasite-specific roles in the biogenesis of their unique secretory organelles. Eukaryotic cells evolved a highly complex endomembrane system, consisting of secretory and endocytic organelles. In the case of apicomplexan parasites unique secretory organelles have evolved that are essential for the invasion of the host cell. Surprisingly these protozoans show a paucity of trafficking factors, such as Rabs and it appears that they lost several factors involved in endocytosis. Here, we demonstrate that Rab5A and Rab5C, normally involved in endocytic uptake, actually regulate secretion in Toxoplasma gondii, since functional ablation of Rab5A or Rab5C results in aberrant transport of proteins to specialised secretory organelles called micronemes and rhoptries. Furthermore, we demonstrate that independent transport routes to micronemes exist indicating that apicomplexans have remodelled Rab5-mediated vesicular traffic into a secretory system that is essential for host cell invasion.
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Affiliation(s)
- Katrin Kremer
- Institute of Infection, Immunity and Inflammation, Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, United Kingdom
| | - Dirk Kamin
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Eva Rittweger
- German Cancer Research Center/BioQuant, Heidelberg, Germany
| | - Jonathan Wilkes
- Institute of Infection, Immunity and Inflammation, Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, United Kingdom
| | - Halley Flammer
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Sabine Mahler
- Parasitology, Department of Infectious Diseases, University of Heidelberg Medical School, Heidelberg, Germany
| | - Joanne Heng
- Institute of Infection, Immunity and Inflammation, Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, United Kingdom
| | | | - Gordon Langsley
- Laboratoire de Biologie Cellulaire Comparative des Apicomplexes, Institut Cochin, Inserm, U567, CNRS, UMR 8104, Faculté de Médecine Paris V – Hôpital Cochin, Paris, France
| | - Stefan W. Hell
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Vernon B. Carruthers
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - David J. P. Ferguson
- Nuffield Department of Pathology, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Markus Meissner
- Institute of Infection, Immunity and Inflammation, Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, United Kingdom
- * E-mail:
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71
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Kemp LE, Yamamoto M, Soldati-Favre D. Subversion of host cellular functions by the apicomplexan parasites. FEMS Microbiol Rev 2012. [PMID: 23186105 DOI: 10.1111/1574-6976.12013] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Rhoptries are club-shaped secretory organelles located at the anterior pole of species belonging to the phylum of Apicomplexa. Parasites of this phylum are responsible for a huge burden of disease in humans and animals and a loss of economic productivity. Members of this elite group of obligate intracellular parasites include Plasmodium spp. that cause malaria and Cryptosporidium spp. that cause diarrhoeal disease. Although rhoptries are almost ubiquitous throughout the phylum, the relevance and role of the proteins contained within the rhoptries varies. Rhoptry contents separate into two intra-organellar compartments, the neck and the bulb. A number of rhoptry neck proteins are conserved between species and are involved in functions such as host cell invasion. The bulb proteins are less well-conserved and probably evolved for a particular lifestyle. In the majority of species studied to date, rhoptry content is involved in formation and maintenance of the parasitophorous vacuole; however some species live free within the host cytoplasm. In this review, we will summarise the knowledge available regarding rhoptry proteins. Specifically, we will discuss the role of the rhoptry kinases that are used by Toxoplasma gondii and other coccidian parasites to subvert the host cellular functions and prevent parasite death.
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Affiliation(s)
- Louise E Kemp
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland.
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Cowper B, Matthews S, Tomley F. The molecular basis for the distinct host and tissue tropisms of coccidian parasites. Mol Biochem Parasitol 2012; 186:1-10. [DOI: 10.1016/j.molbiopara.2012.08.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 08/29/2012] [Accepted: 08/29/2012] [Indexed: 01/20/2023]
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Evolution of apicomplexan secretory organelles. Int J Parasitol 2012; 42:1071-81. [PMID: 23068912 DOI: 10.1016/j.ijpara.2012.09.009] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 09/16/2012] [Accepted: 09/17/2012] [Indexed: 12/26/2022]
Abstract
The alveolate superphylum includes many free-living and parasitic organisms, which are united by the presence of alveolar sacs lying proximal to the plasma membrane, providing cell structure. All species comprising the apicomplexan group of alveolates are parasites and have adapted to the unique requirements of the parasitic lifestyle. Here the evolution of apicomplexan secretory organelles that are involved in the critical process of egress from one cell and invasion of another is explored. The variations within the Apicomplexa and how these relate to species-specific biology will be discussed. In addition, recent studies have identified specific calcium-sensitive molecules that coordinate the various events and regulate the release of these secretory organelles within apicomplexan parasites. Some aspects of this machinery are conserved outside the Apicomplexa, and are beginning to elucidate the conserved nature of the machinery. Briefly, the relationship of this secretion machinery within the Apicomplexa will be discussed, compared with free-living and predatory alveolates, and how these might have evolved from a common ancestor.
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74
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Jacot D, Soldati-Favre D. Does protein phosphorylation govern host cell entry and egress by the Apicomplexa? Int J Med Microbiol 2012; 302:195-202. [DOI: 10.1016/j.ijmm.2012.07.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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75
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Dubremetz JF, Lebrun M. Virulence factors of Toxoplasma gondii. Microbes Infect 2012; 14:1403-10. [PMID: 23006855 DOI: 10.1016/j.micinf.2012.09.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 09/03/2012] [Accepted: 09/04/2012] [Indexed: 11/28/2022]
Abstract
Toxoplasma gondii virulence is dependent on factors involved in either parasite-host cell interaction, or in host immune response. It is essentially defined in the mouse and little is known concerning human infection. The genetic dependence of virulence is a growing field, benefiting from the recent development of research of the population structure of T. gondii.
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Affiliation(s)
- Jean François Dubremetz
- UMR 5235 CNRS, Université de Montpellier 2, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France.
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76
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Dziadek B, Brzostek A. Recombinant ROP2, ROP4, GRA4 and SAG1 antigen-cocktails as possible tools for immunoprophylaxis of toxoplasmosis: what's next? Bioengineered 2012; 3:358-64. [PMID: 22892593 DOI: 10.4161/bioe.21541] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Toxoplasmosis is a globally distributed foodborne zoonosis caused by a protozoan parasite Toxoplasma gondii. Usually asymptomatic in immunocompetent humans, toxoplasmosis is a serious clinical and veterinary problem often leading to lethal damage in an infected host. In order to overcome the exceptionally strong clinical and socio-economic impact of Toxoplasma infection, the construction of an effective vaccine inducing full immunoprotection against the parasite is an urgent issue. In the last two decades many live attenuated, subunit and DNA-based vaccines against toxoplasmosis have been studied, however only partial protection conferred by vaccination against chronic as well as acute infection has been achieved. Among various immunization strategies, no viable subunit vaccines based on recombinant secretory (ROP2, ROP4 and GRA4) and surface (SAG1) T. gondii proteins have been found as attractive tools for further studies. This is due to their high, but still partial, protective efficacy correlated with the induction of cellular and humoral immune responses.
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Affiliation(s)
- Bozena Dziadek
- Department of Immunoparasitology; University of Lodz, Lodz, Poland.
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77
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Singh S, Chitnis CE. Signalling mechanisms involved in apical organelle discharge during host cell invasion by apicomplexan parasites. Microbes Infect 2012; 14:820-4. [PMID: 22634343 DOI: 10.1016/j.micinf.2012.05.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Revised: 04/28/2012] [Accepted: 05/02/2012] [Indexed: 11/17/2022]
Abstract
Malaria is caused by Plasmodium parasites, which belong to the phylum apicomplexa. The characteristic feature of apicomplexan parasites is the presence of apical organelles, referred to as micronemes and rhoptries, in the invasive stages of the parasite life cycle. Survival of these obligate intracellular parasites depends on successful invasion of host cells, which is mediated by specific molecular interactions between host receptors and parasite ligands that are commonly stored in these apical organelles. The timely release of these ligands from apical organelles to the parasite surface is crucial for receptor engagement and invasion. This article is a broad overview of the signalling mechanisms that control the regulated secretion of apical organelles during host cell invasion by apicomplexan parasites.
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Affiliation(s)
- Shailja Singh
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi 110067, India.
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78
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Shen B, Sibley LD. The moving junction, a key portal to host cell invasion by apicomplexan parasites. Curr Opin Microbiol 2012; 15:449-55. [PMID: 22445360 DOI: 10.1016/j.mib.2012.02.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 02/23/2012] [Indexed: 10/28/2022]
Abstract
One defining feature of apicomplexan parasites is their special ability to actively invade host cells. Although rapid, invasion is a complicated process that requires coordinated activities of host cell attachment, protein secretion, and motility by the parasite. Central to this process is the establishment of a structure called moving junction (MJ), which forms a tight connection between invading parasite and host cell membranes through which the parasite passes to enter into the host. Although recognized microscopically for decades, molecular characterization of the MJ was only enabled by the recent discovery of components that make up this multi-protein complex. Exciting progress made during the past few years on both the structure and function of the components of the MJ is reviewed here.
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Affiliation(s)
- Bang Shen
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110-1093, USA
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79
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Malcolm H, April H. The magnesium inhibition and arrested phagosome hypotheses: new perspectives on the evolution and ecology ofSymbiodiniumsymbioses. Biol Rev Camb Philos Soc 2012; 87:804-21. [DOI: 10.1111/j.1469-185x.2012.00223.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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80
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Abstract
Infection with the protozoan parasite Toxoplasma gondii is characterized by asymptomatic latent infection in the central nervous system and skeletal muscle tissue in the majority of immunocompentent individuals. Life-threatening reactivation of the infection in immunocompromized patients originates from rupture of Toxoplasma cysts in the brain. While major progress has been made in our understanding of the immunopathogenesis of infection the mechanism(s) of neuroinvasion of the parasite remains poorly understood. The present review presents the current understanding of blood-brain barrier (patho)physiology and the interaction of Toxoplasma gondii with cells of the blood-brain barrier.
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Affiliation(s)
- Sabrina M Feustel
- Institute for Microbiology and Hygiene, Charité Medical School, Berlin, Germany
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81
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M Santos J, Graindorge A, Soldati-Favre D. New insights into parasite rhomboid proteases. Mol Biochem Parasitol 2011; 182:27-36. [PMID: 22173057 DOI: 10.1016/j.molbiopara.2011.11.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 11/24/2011] [Accepted: 11/28/2011] [Indexed: 11/16/2022]
Abstract
The rhomboid-like proteins constitute a large family of intramembrane serine proteases that are present in all branches of life. First studied in Drosophila, these enzymes catalyse the release of the active forms of proteins from the membrane and hence trigger signalling events. In protozoan parasites, a limited number of rhomboid-like proteases have been investigated and some of them are associated to pathogenesis. In Apicomplexans, rhomboid-like protease activity is involved in shedding adhesins from the surface of the zoites during motility and host cell entry. Recently, a Toxoplasma gondii rhomboid was also implicated in an intracellular signalling mechanism leading to parasite proliferation. In Entamoeba histolytica, the capacity to adhere to host cells and to phagocytose cells is potentiated by a rhomboid-like protease. Survey of a small number of protozoan parasite genomes has uncovered species-specific rhomboid-like protease genes, many of which are predicted to encode inactive enzymes. Functional investigation of the rhomboid-like proteases in other protozoan parasites will likely uncover novel and unexpected implications for this family of proteases.
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Affiliation(s)
- Joana M Santos
- Department of Microbiology, Faculty of Medicine, University of Geneva, 1 Rue-Michel Servet, 1211 Geneva 4, Switzerland
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Payne TM, Lund PJ, Knoll LJ. A transmembrane domain containing pellicle protein of Toxoplasma gondii enhances virulence and invasion after extracellular stress. Mol Biochem Parasitol 2011; 179:107-10. [PMID: 21669237 PMCID: PMC3156857 DOI: 10.1016/j.molbiopara.2011.05.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 05/07/2011] [Accepted: 05/27/2011] [Indexed: 11/19/2022]
Abstract
To identify Toxoplasma gondii genes important in the establishment of a persistent infection, we previously used signature-tagged mutagenesis to identify mutants with reduced cyst numbers in the brains of mice. One of the mutants, 95C5, has an insertion within a predicted six transmembrane domain protein, which localizes to the parasite pellicle, thus we named it transmembrane pellicle protein 1 (TgTPP1). Although the 95C5 mutant was found be reduced in its ability to form brain cysts, it is defective during acute infection. Addition of TgTPP1 expressed from its endogenous promoter restored the acute lethality of the 95C5 mutant to parental levels. The 95C5 mutant does not have a growth defect in standard tissue culture conditions; however, we found a significant defect in host cell penetration after extracellular stress. Overall, TgTPP1 may function during acute infection by enhancing the parasites ability to invade after extracellular stress.
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Affiliation(s)
- T. Matthew Payne
- Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Microbial Sciences Building Room 3345, 1550 Linden Drive, Madison, WI 53706, United States of America
| | - Peder J. Lund
- Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Microbial Sciences Building Room 3345, 1550 Linden Drive, Madison, WI 53706, United States of America
| | - Laura J. Knoll
- Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Microbial Sciences Building Room 3345, 1550 Linden Drive, Madison, WI 53706, United States of America
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83
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Neospora caninum: comparative gene expression profiling of Neospora caninum wild type and a temperature sensitive clone. Exp Parasitol 2011; 129:346-54. [PMID: 21963790 DOI: 10.1016/j.exppara.2011.09.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 09/13/2011] [Accepted: 09/16/2011] [Indexed: 11/21/2022]
Abstract
To understand the genetic basis of virulence, gene expression profiles of a temperature-sensitive clone (NCts-8, relatively avirulent) and its wild type (NC-1) of Neospora caninum were characterized and compared using a high-density microarray with approximately 63,000 distinct oligonucleotides. This microarray consists of 5692 unique N. caninum sequences, including 1980 Tentative Consensus sequences and 3712 singleton ESTs from the TIGR N. caninum Gene Index (NCGI, release 5.0). Each sequence was represented by 11 distinct 60mer oligonucleotides synthesized in situ on the microarray. The results showed that 111 genes were significantly repressed and no up-regulated genes were identified in the NCts-8 clone. The level of 10 randomly selected genes from the repressed genes was confirmed using real-time RT-PCR. Of the 111 repressed genes, 58 were hypothetical protein products and 53 were annotated genes. Over 70% of the repressed genes identified in this study are clustered on five chromosomes (I, VII, VIII, X and XII). These results suggest that the down-regulated genes may be in part responsible for the reduced pathogenesis of NCts-8; further characterization of the regulated genes may aid in understanding of molecular basis of virulence and development of countermeasures against neosporosis.
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84
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Tyler JS, Treeck M, Boothroyd JC. Focus on the ringleader: the role of AMA1 in apicomplexan invasion and replication. Trends Parasitol 2011; 27:410-20. [PMID: 21659001 PMCID: PMC3159806 DOI: 10.1016/j.pt.2011.04.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 04/08/2011] [Accepted: 04/12/2011] [Indexed: 10/18/2022]
Abstract
Apicomplexan parasites exhibit an unusual mechanism of host cell penetration. A central player in this process is the protein apical membrane antigen 1 (AMA1). Although essential for invasion, the precise functional roles AMA1 plays have been unclear. Several recent studies have provided important functional insight into its role within the multiprotein complex that comprises the moving junction (MJ). Initially formed at the apical tip of the invading parasite, the MJ represents a ring-like region of contact between the surfaces of the invading parasite and the host cell as the invaginated host plasma membrane is forced inward by the penetrating parasite. This review discusses these and other recent insights into AMA1 with particular emphasis on studies conducted in Plasmodium and Toxoplasma.
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Affiliation(s)
- Jessica S. Tyler
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305 U.S.A
| | - Moritz Treeck
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305 U.S.A
| | - John C. Boothroyd
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305 U.S.A
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85
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Stutz A, Kessler H, Kaschel ME, Meissner M, Dalpke AH. Cell invasion and strain dependent induction of suppressor of cytokine signaling-1 by Toxoplasma gondii. Immunobiology 2011; 217:28-36. [PMID: 22015046 DOI: 10.1016/j.imbio.2011.08.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 08/17/2011] [Accepted: 08/21/2011] [Indexed: 01/12/2023]
Abstract
Toxoplasma gondii is an intracellular parasite that has to cope with the microbicidal actions of IFNγ. Previously we reported that parasite-mediated induction of suppressor of cytokine signaling protein 1 (SOCS1) contributes to inhibition of IFNγ signaling. However, the signaling requirements remained elusive. We now show that induction of SOCS1 and inhibition of nitric oxide production by IFNγ was independent of stimulation of Toll-like receptors. Instead, infection by T. gondii resulted in induction of egr transcription factors which have been reported to regulate SOCS expression. Indeed, induction of egr2 as well as SOCS1 was dependent on p38 MAP kinase and blockade of egr inhibited SOCS1 expression. Moreover, we found that Mic8, a previously identified invasion factor of T. gondii, was necessary for SOCS1 regulation and escape of IFNγ mediated nitric oxide secretion within macrophages. Surprisingly, when further analyzing Mic8 deficient parasites we noted that inhibition of IFNγ mediated up-regulation of MHC-class II and ICAM1 molecules was independent of cell invasion. Furthermore, these inhibitory effects were equally observed in type I and II strains of T. gondii and were dependent on excreted and secreted antigens. In contrast, only the virulent RH type I strain additionally induced SOCS1 and efficiently inhibited nitric oxide secretion by IFNγ. The results show that T. gondii makes use of two different mechanisms to escape from IFNγ activity with one mode being strain dependent and relying on active cell invasion and SOCS1 induction.
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Affiliation(s)
- Andrea Stutz
- Dept. of Infectious Diseases - Medical Microbiology and Hygiene, University Heidelberg, 69120 Heidelberg, Germany
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86
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Gaur D, Chitnis CE. Molecular interactions and signaling mechanisms during erythrocyte invasion by malaria parasites. Curr Opin Microbiol 2011; 14:422-8. [PMID: 21803641 DOI: 10.1016/j.mib.2011.07.018] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2011] [Revised: 07/11/2011] [Accepted: 07/12/2011] [Indexed: 01/24/2023]
Abstract
Invasion of erythrocytes by Plasmodium merozoites is a complex process that is mediated by specific molecular interactions. Here, we review recent studies on interactions between erythrocyte binding antigens (EBA) and PfRH proteins from the parasite and erythrocyte receptors involved in invasion. The timely release of these parasite ligands from internal organelles such as micronemes and rhoptries to the merozoite surface is critical for receptor-engagement leading to successful invasion. We review information on signaling mechanisms that control the regulated secretion of parasite proteins during invasion. Erythrocyte invasion involves the formation and movement of a junction between the invading merozoite and host erythrocyte. We review recent studies on the molecular composition of the junction and the molecular motor that drives movement of the junction.
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Affiliation(s)
- Deepak Gaur
- International Centre for Genetic Engineering and Biotechnology, New Delhi, India
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87
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Gaji RY, Flammer HP, Carruthers VB. Forward targeting of Toxoplasma gondii proproteins to the micronemes involves conserved aliphatic amino acids. Traffic 2011; 12:840-53. [PMID: 21438967 PMCID: PMC3115430 DOI: 10.1111/j.1600-0854.2011.01192.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Like other apicomplexan parasites, Toxoplasma gondii actively invades host cells using a combination of secretory proteins and an acto-myosin motor system. Micronemes are the first set of proteins secreted during invasion that play an essential role in host cell entry. Many microneme proteins (MICs) function in protein complexes, and each complex contains at least one protein that displays a cleavable propeptide. Although MIC propeptides have been implicated in forward targeting to micronemes, the specific amino acids involved have not been identified. It was also not known if the propeptide has a general function in MICs trafficking in T. gondii and other apicomplexans. Here we show that propeptide domains are extensively interchangeable between T. gondii MICs and also with that of Eimeria tenella MIC5 (EtMIC5), suggesting a common mechanism of function. We also performed N-terminal deletion and mutational analysis of M2AP and MIC5 propeptides to show that a valine at position +3 (relative to signal peptidase cleavage) of proM2AP and a leucine at position +1 of proMIC5 are crucial for targeting to micronemes. Valine and leucine are closely related amino acids with similar side chains, implying a similar mode of function, a notion that was confirmed by correct trafficking of TgM2AP-V/L and TgMIC5-L/V substitution mutants. Propeptides of AMA1, MIC3 and EtMIC5 have valine or leucine at or near the N-termini and mutagenesis of these conserved residues validated their role in microneme trafficking. Collectively, our findings suggest that discrete, aliphatic residues at the extreme N-termini of proMICs facilitate trafficking to the micronemes.
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Affiliation(s)
- Rajshekhar Y Gaji
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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88
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Santos JM, Soldati-Favre D. Invasion factors are coupled to key signalling events leading to the establishment of infection in apicomplexan parasites. Cell Microbiol 2011; 13:787-96. [DOI: 10.1111/j.1462-5822.2011.01585.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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89
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The RON2-AMA1 interaction is a critical step in moving junction-dependent invasion by apicomplexan parasites. PLoS Pathog 2011; 7:e1001276. [PMID: 21347343 PMCID: PMC3037350 DOI: 10.1371/journal.ppat.1001276] [Citation(s) in RCA: 246] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 01/07/2011] [Indexed: 11/20/2022] Open
Abstract
Obligate intracellular Apicomplexa parasites share a unique invasion mechanism involving a tight interaction between the host cell and the parasite surfaces called the moving junction (MJ). The MJ, which is the anchoring structure for the invasion process, is formed by secretion of a macromolecular complex (RON2/4/5/8), derived from secretory organelles called rhoptries, into the host cell membrane. AMA1, a protein secreted from micronemes and associated with the parasite surface during invasion, has been shown in vitro to bind the MJ complex through a direct association with RON2. Here we show that RON2 is inserted as an integral membrane protein in the host cell and, using several interaction assays with native or recombinant proteins, we define the region that binds AMA1. Our studies were performed both in Toxoplasma gondii and Plasmodium falciparum and although AMA1 and RON2 proteins have diverged between Apicomplexa species, we show an intra-species conservation of their interaction. More importantly, invasion inhibition assays using recombinant proteins demonstrate that the RON2-AMA1 interaction is crucial for both T. gondii and P. falciparum entry into their host cells. This work provides the first evidence that AMA1 uses the rhoptry neck protein RON2 as a receptor to promote invasion by Apicomplexa parasites.
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90
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Friedrich N, Matthews S, Soldati-Favre D. Sialic acids: key determinants for invasion by the Apicomplexa. Int J Parasitol 2010; 40:1145-54. [PMID: 20430033 DOI: 10.1016/j.ijpara.2010.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 04/17/2010] [Accepted: 04/19/2010] [Indexed: 11/20/2022]
Abstract
Sialic acids are ubiquitously found on the surface of all vertebrate cells at the extremities of glycan chains and widely exploited by viruses and bacteria to enter host cells. Carbohydrate-bearing receptors are equally important for host cell invasion by the obligate intracellular protozoan parasites of the phylum Apicomplexa. Host cell entry is an active process relying crucially on proteins that engage with receptors on the host cell surface and promote adhesion and internalisation. Assembly into complexes, proteolytic processing and oligomerization are important requirements for the functionality of these adhesins. The combination of adhesive proteins with varying stringency in specificity confers some flexibility to the parasite in face of receptor heterogeneity and immune pressure. Sialic acids are now recognised to critically contribute to selective host cell recognition by various species of the phylum.
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Affiliation(s)
- Nikolas Friedrich
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 Rue Michel-Servet, CH-1211 Geneva 4, Switzerland
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91
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Sheiner L, Santos JM, Klages N, Parussini F, Jemmely N, Friedrich N, Ward GE, Soldati-Favre D. Toxoplasma gondii transmembrane microneme proteins and their modular design. Mol Microbiol 2010; 77:912-29. [PMID: 20545864 PMCID: PMC2982875 DOI: 10.1111/j.1365-2958.2010.07255.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Host cell invasion by the Apicomplexa critically relies on regulated secretion of transmembrane micronemal proteins (TM-MICs). Toxoplasma gondii possesses functionally non-redundant MIC complexes that participate in gliding motility, host cell attachment, moving junction formation, rhoptry secretion and invasion. The TM-MICs are released onto the parasite's surface as complexes capable of interacting with host cell receptors. Additionally, TgMIC2 simultaneously connects to the actomyosin system via binding to aldolase. During invasion these adhesive complexes are shed from the surface notably via intramembrane cleavage of the TM-MICs by a rhomboid protease. Some TM-MICs act as escorters and assure trafficking of the complexes to the micronemes. We have investigated the properties of TgMIC6, TgMIC8, TgMIC8.2, TgAMA1 and the new micronemal protein TgMIC16 with respect to interaction with aldolase, susceptibility to rhomboid cleavage and presence of trafficking signals. We conclude that several TM-MICs lack targeting information within their C-terminal domains, indicating that trafficking depends on yet unidentified proteins interacting with their ectodomains. Most TM-MICs serve as substrates for a rhomboid protease and some of them are able to bind to aldolase. We also show that the residues responsible for binding to aldolase are essential for TgAMA1 but dispensable for TgMIC6 function during invasion.
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Affiliation(s)
- Lilach Sheiner
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland Phone: + 41 22 379 5656, Fax: + 41 22 379 5702
| | - Joana M. Santos
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland Phone: + 41 22 379 5656, Fax: + 41 22 379 5702
| | - Natacha Klages
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland Phone: + 41 22 379 5656, Fax: + 41 22 379 5702
| | - Fabiola Parussini
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont 05405, USA
| | - Noelle Jemmely
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland Phone: + 41 22 379 5656, Fax: + 41 22 379 5702
| | - Nikolas Friedrich
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland Phone: + 41 22 379 5656, Fax: + 41 22 379 5702
| | - Gary E. Ward
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont 05405, USA
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland Phone: + 41 22 379 5656, Fax: + 41 22 379 5702
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92
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Buguliskis JS, Brossier F, Shuman J, Sibley LD. Rhomboid 4 (ROM4) affects the processing of surface adhesins and facilitates host cell invasion by Toxoplasma gondii. PLoS Pathog 2010; 6:e1000858. [PMID: 20421941 PMCID: PMC2858701 DOI: 10.1371/journal.ppat.1000858] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Accepted: 03/15/2010] [Indexed: 11/18/2022] Open
Abstract
Host cell attachment by Toxoplasma gondii is dependent on polarized secretion of apical adhesins released from the micronemes. Subsequent translocation of these adhesive complexes by an actin-myosin motor powers motility and host cell invasion. Invasion and motility are also accompanied by shedding of surface adhesins by intramembrane proteolysis. Several previous studies have implicated rhomboid proteases in this step; however, their precise roles in vivo have not been elucidated. Using a conditional knockout strategy, we demonstrate that TgROM4 participates in processing of surface adhesins including MIC2, AMA1, and MIC3. Suppression of TgROM4 led to decreased release of the adhesin MIC2 into the supernatant and concomitantly increased the surface expression of this and a subset of other adhesins. Suppression of TgROM4 resulted in disruption of normal gliding, with the majority of parasites twirling on their posterior ends. Parasites lacking TgROM4 bound better to host cells, but lost the ability to apically orient and consequently most failed to generate a moving junction; hence, invasion was severely impaired. Our findings indicate that TgROM4 is involved in shedding of micronemal proteins from the cell surface. Down regulation of TgROM4 disrupts the normal apical-posterior gradient of adhesins that is important for efficient cell motility and invasion of host cells by T. gondii. Apicomplexan parasites invade host cells using a multi-step process that depends on regulated secretion of adhesins, attachment to the cell, and active penetration. Coordinating these activities requires control of proper timing and release of surface proteins that mediate adhesion. Parasites like Toxoplasma gondii attach directionally to their host cells due to the selective discharge of adhesive proteins at their apical end. The resulting complexes are then translocated along the long axis of the parasite, thus propelling the parasite into the cell. Completion of cell invasion also requires that these interactions ultimately be severed to allow detachment. Shedding is accomplished by proteolytic cleavage of the adhesive proteins at the point where they span the parasite outer membrane. By disrupting the expression of the intramembrane protease rhomboid 4 (ROM4), we demonstrate that it is important for shedding of adhesins. In the absence of ROM4, a subset of surface adhesive proteins was over-expressed on the parasite cell surface. Although ROM4 knockdown parasites bound better to host cells, they lost their ability to do so directionally, and hence were impaired in cell entry. Our findings demonstrate that host cell invasion by apicomplexan parasites relies on constitutive shedding of surface adhesins for efficient infection.
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Affiliation(s)
- Jeffrey S. Buguliskis
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Fabien Brossier
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Joel Shuman
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - L. David Sibley
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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93
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Liu MM, Yuan ZG, Peng GH, Zhou DH, He XH, Yan C, Yin CC, He Y, Lin RQ, Song HQ, Zhu XQ. Toxoplasma gondii microneme protein 8 (MIC8) is a potential vaccine candidate against toxoplasmosis. Parasitol Res 2010; 106:1079-84. [DOI: 10.1007/s00436-010-1742-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Accepted: 01/13/2010] [Indexed: 12/15/2022]
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94
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Zhou BH, Wang HW, Wang XY, Zhang LF, Zhang KY, Xue FQ. Eimeria tenella: effects of diclazuril treatment on microneme genes expression in second-generation merozoites and pathological changes of caeca in parasitized chickens. Exp Parasitol 2010; 125:264-70. [PMID: 20138868 DOI: 10.1016/j.exppara.2010.01.022] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Revised: 01/26/2010] [Accepted: 01/27/2010] [Indexed: 01/09/2023]
Abstract
The effects of diclazuril on mRNA expression levels of invasion-related microneme genes were examined in second-generation merozoites of Eimeria tenella (E. tenella) by quantitative real-time (QRT) PCR. Diclazruil treatment of infected chickens significantly decreased the number of second-generation merozoites by 65.13%, and resulted in downregulation of EtMIC genes: EtMIC1 by 65.63%, EtMIC2 by 64.12%, EtMIC3 by 56.82%, EtMIC4 by 73.48%, and EtMIC5 by 78.17%. SEM images of caecum tissue from uninfected chickens showed regular intestinal villus structure. In infected chickens, a distinct loss of the superficial epithelium, with a flattened mucosa and large-area necrosis and anabrosis, was evident. In diclazruil-treated chickens, a decrease in merozoite number and a visibly improved appearance of the caeca were noted. These improvements appeared to be mediated in part by downregulation of the expression of invasion-related EtMIC genes in response to diclazuril.
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Affiliation(s)
- Bian-hua Zhou
- Key Laboratory of Veterinary Drug Safety Evaluation and Residues Research, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, People's Republic of China
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95
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Distinct external signals trigger sequential release of apical organelles during erythrocyte invasion by malaria parasites. PLoS Pathog 2010; 6:e1000746. [PMID: 20140184 PMCID: PMC2816683 DOI: 10.1371/journal.ppat.1000746] [Citation(s) in RCA: 219] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Accepted: 12/31/2009] [Indexed: 11/24/2022] Open
Abstract
The invasion of erythrocytes by Plasmodium merozoites requires specific interactions between host receptors and parasite ligands. Parasite proteins that bind erythrocyte receptors during invasion are localized in apical organelles called micronemes and rhoptries. The regulated secretion of microneme and rhoptry proteins to the merozoite surface to enable receptor binding is a critical step in the invasion process. The sequence of these secretion events and the external signals that trigger release are not known. We have used time-lapse video microscopy to study changes in intracellular calcium levels in Plasmodium falciparum merozoites during erythrocyte invasion. In addition, we have developed flow cytometry based methods to measure relative levels of cytosolic calcium and study surface expression of apical organelle proteins in P. falciparum merozoites in response to different external signals. We demonstrate that exposure of P. falciparum merozoites to low potassium ion concentrations as found in blood plasma leads to a rise in cytosolic calcium levels through a phospholipase C mediated pathway. Rise in cytosolic calcium triggers secretion of microneme proteins such as the 175 kD erythrocyte binding antigen (EBA175) and apical membrane antigen-1 (AMA-1) to the merozoite surface. Subsequently, interaction of EBA175 with glycophorin A (glyA), its receptor on erythrocytes, restores basal cytosolic calcium levels and triggers release of rhoptry proteins. Our results identify for the first time the external signals responsible for the sequential release of microneme and rhoptry proteins during erythrocyte invasion and provide a starting point for the dissection of signal transduction pathways involved in regulated exocytosis of these key apical organelles. Signaling pathway components involved in apical organelle discharge may serve as novel targets for drug development since inhibition of microneme and rhoptry secretion can block invasion and limit blood-stage parasite growth. Malaria remains a major public health problem in many parts of the tropical world. All the clinical symptoms of malaria are attributed to the blood stage of the parasite life cycle during which Plasmodium merozoites invade and multiply within host erythrocytes. Invasion by Plasmodium merozoites is a complex process that requires multiple molecular interactions between the invading parasite and target erythrocyte. Parasite proteins that mediate such interactions are localized in membrane bound internal organelles at the apical end of merozoites called micronemes and rhoptries. The timely secretion of microneme and rhoptry proteins to the merozoite surface to allow receptor binding is a crucial step in the invasion process. In this study, we demonstrate that exposure of Plasmodium falciparum merozoites to low potassium ion concentrations as found in blood plasma provides the natural signal that triggers a rise in intracellular calcium, which in turn triggers secretion of microneme proteins to the merozoite surface. Subsequently, binding of released microneme proteins with erythrocyte receptors provides the signal for release of rhoptry proteins. These studies open the path for analysis of signal transduction pathways involved in apical organelle secretion. A clear understanding of these pathways will enable development of inhibitors that block secretion of key parasite proteins required for receptor-binding. Such inhibitors will block erythrocyte invasion and inhibit parasite growth, providing promising leads for development of novel drugs against malaria.
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96
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4-Bromophenacyl bromide specifically inhibits rhoptry secretion during Toxoplasma invasion. PLoS One 2009; 4:e8143. [PMID: 19956582 PMCID: PMC2780294 DOI: 10.1371/journal.pone.0008143] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Accepted: 11/10/2009] [Indexed: 11/26/2022] Open
Abstract
Toxoplasma gondii is a eukaryotic parasite of the phylum Apicomplexa that is able to infect a wide variety of host cells. During its active invasion process it secretes proteins from discrete secretory organelles: the micronemes, rhoptries and dense granules. Although a number of rhoptry proteins have been shown to be involved in important interactions with the host cell, very little is known about the mechanism of secretion of any Toxoplasma protein into the host cell. We used a chemical inhibitor of phospholipase A2s, 4-bromophenacyl bromide (4-BPB), to look at the role of such lipases in the secretion of Toxoplasma proteins. We found that 4-BPB was a potent inhibitor of rhoptry secretion in Toxoplasma invasion. This drug specifically blocked rhoptry secretion but not microneme secretion, thus effectively showing that the two processes can be de-coupled. It affected parasite motility and invasion, but not attachment or egress. Using propargyl- or azido-derivatives of the drug (so-called click chemistry derivatives) and a series of 4-BPB-resistant mutants, we found that the drug has a very large number of target proteins in the parasite that are involved in at least two key steps: invasion and intracellular growth. This potent compound, the modified “click-chemistry” forms of it, and the resistant mutants should serve as useful tools to further study the processes of Toxoplasma early invasion, in general, and rhoptry secretion, in particular.
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97
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Heaslip AT, Ems-McClung SC, Hu K. TgICMAP1 is a novel microtubule binding protein in Toxoplasma gondii. PLoS One 2009; 4:e7406. [PMID: 19823689 PMCID: PMC2758671 DOI: 10.1371/journal.pone.0007406] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Accepted: 09/16/2009] [Indexed: 01/06/2023] Open
Abstract
The microtubule cytoskeleton provides essential structural support for all eukaryotic cells and can be assembled into various higher order structures that perform drastically different functions. Understanding how microtubule-containing assemblies are built in a spatially and temporally controlled manner is therefore fundamental to understanding cell physiology. Toxoplasma gondii, a protozoan parasite, contains at least five distinct tubulin-containing structures, the spindle pole, centrioles, cortical microtubules, the conoid, and the intra-conoid microtubules. How these five structurally and functionally distinct sets of tubulin containing structures are constructed and maintained in the same cell is an intriguing problem. Previously, we performed a proteomic analysis of the T. gondii apical complex, a cytoskeletal complex located at the apical end of the parasite that is composed of the conoid, three ring-like structures, and the two short intra-conoid microtubules. Here we report the characterization of one of the proteins identified in that analysis, TgICMAP1. We show that TgICMAP1 is a novel microtubule binding protein that can directly bind to microtubules in vitro and stabilizes microtubules when ectopically expressed in mammalian cells. Interestingly, in T. gondii, TgICMAP1 preferentially binds to the intra-conoid microtubules, providing us the first molecular tool to investigate the intra-conoid microtubule assembly process during daughter construction.
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Affiliation(s)
- Aoife T. Heaslip
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | | | - Ke Hu
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
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98
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Phenotypic and gene expression changes among clonal type I strains of Toxoplasma gondii. EUKARYOTIC CELL 2009; 8:1828-36. [PMID: 19801420 DOI: 10.1128/ec.00150-09] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Toxoplasma gondii has an unusual population structure consisting of three clonal lineages that predominate in North America and Europe. This simple pattern has encouraged the use of only a few laboratory isolates that are representative of each lineage. Principle among these is the type I RH strain, originally isolated from a child with encephalitis some 70 years ago. Comparison of different passages of the RH strain that have been propagated differently over the intervening time period revealed that the commonly used clonal line called RH-ERP was not representative of natural isolates of the type I lineage. Notably, RH-ERP formed much larger plaques than other type 1 strains, including a separate, earlier derived isolate of the RH strain. The RH-ERP variant also showed enhanced extracellular survival, faster growth, and decreased differentiation compared to the prototype type I strain GT1. Comparison of gene expression differences in the RH-ERP line revealed that several ABC transporters were upregulated, which may provide a growth advantage in vitro. These findings illustrate that dramatic phenotypic changes can arise in laboratory strains, emphasizing the need for comparison with recent clinical isolates.
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99
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Gilson PR, Crabb BS. Do apicomplexan parasite-encoded proteins act as both ligands and receptors during host cell invasion? F1000 BIOLOGY REPORTS 2009; 1:64. [PMID: 20209017 PMCID: PMC2832315 DOI: 10.3410/b1-64] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Apicomplexan parasites are responsible for a wide range of diseases in animals, including humans, in whom Plasmodium species cause the devastating disease malaria. Several recent discoveries now indicate that these intracellular parasites may use a conserved mechanism to infect their host cells by using parasite-encoded proteins as both parasite ligands and receptors anchored to the host cells.
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Affiliation(s)
- Paul R Gilson
- Macfarlane Burnet Institute for Medical Research and Public Health85 Commercial Road, Melbourne, Victoria 3004Australia
| | - Brendan S Crabb
- Macfarlane Burnet Institute for Medical Research and Public Health85 Commercial Road, Melbourne, Victoria 3004Australia
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100
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Del Carmen MG, Mondragón M, González S, Mondragón R. Induction and regulation of conoid extrusion inToxoplasma gondii. Cell Microbiol 2009; 11:967-82. [DOI: 10.1111/j.1462-5822.2009.01304.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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