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Herneisen AL, Peters ML, Smith TA, Shortt E, Lourido S. SPARK regulates AGC kinases central to the Toxoplasma gondii asexual cycle. eLife 2024; 13:RP93877. [PMID: 39136687 PMCID: PMC11321763 DOI: 10.7554/elife.93877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2024] Open
Abstract
Apicomplexan parasites balance proliferation, persistence, and spread in their metazoan hosts. AGC kinases, such as PKG, PKA, and the PDK1 ortholog SPARK, integrate environmental signals to toggle parasites between replicative and motile life stages. Recent studies have cataloged pathways downstream of apicomplexan PKG and PKA; however, less is known about the global integration of AGC kinase signaling cascades. Here, conditional genetics coupled to unbiased proteomics demonstrates that SPARK complexes with an elongin-like protein to regulate the stability of PKA and PKG in the model apicomplexan Toxoplasma gondii. Defects attributed to SPARK depletion develop after PKG and PKA are down-regulated. Parasites lacking SPARK differentiate into the chronic form of infection, which may arise from reduced activity of a coccidian-specific PKA ortholog. This work delineates the signaling topology of AGC kinases that together control transitions within the asexual cycle of this important family of parasites.
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Affiliation(s)
- Alice L Herneisen
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Michelle L Peters
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Tyler A Smith
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Emily Shortt
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Sebastian Lourido
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
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2
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Herneisen AL, Peters ML, Smith TA, Shortt E, Lourido S. SPARK regulates AGC kinases central to the Toxoplasma gondii asexual cycle. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.30.564746. [PMID: 37961644 PMCID: PMC10634940 DOI: 10.1101/2023.10.30.564746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Apicomplexan parasites balance proliferation, persistence, and spread in their metazoan hosts. AGC kinases, such as PKG, PKA, and the PDK1 ortholog SPARK, integrate environmental signals to toggle parasites between replicative and motile life stages. Recent studies have cataloged pathways downstream of apicomplexan PKG and PKA; however, less is known about the global integration of AGC kinase signaling cascades. Here, conditional genetics coupled to unbiased proteomics demonstrates that SPARK complexes with an elongin-like protein to regulate the stability of PKA and PKG in the model apicomplexan Toxoplasma gondii. Defects attributed to SPARK depletion develop after PKG and PKA are down-regulated. Parasites lacking SPARK differentiate into the chronic form of infection, which may arise from reduced activity of a coccidian-specific PKA ortholog. This work delineates the signaling topology of AGC kinases that together control transitions within the asexual cycle of this important family of parasites.
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Affiliation(s)
- Alice L. Herneisen
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA
| | - Michelle L. Peters
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA
| | - Tyler A. Smith
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA
| | - Emily Shortt
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA
| | - Sebastian Lourido
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA
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3
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Hortua Triana MA, Márquez-Nogueras KM, Fazli MS, Quinn S, Moreno SNJ. Regulation of calcium entry by cyclic GMP signaling in Toxoplasma gondii. J Biol Chem 2024; 300:105771. [PMID: 38382669 PMCID: PMC10959671 DOI: 10.1016/j.jbc.2024.105771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 01/09/2024] [Accepted: 01/28/2024] [Indexed: 02/23/2024] Open
Abstract
Ca2+ signaling impacts almost every aspect of cellular life. Ca2+ signals are generated through the opening of ion channels that permit the flow of Ca2+ down an electrochemical gradient. Cytosolic Ca2+ fluctuations can be generated through Ca2+ entry from the extracellular milieu or release from intracellular stores. In Toxoplasma gondii, Ca2+ ions play critical roles in several essential functions for the parasite, like invasion of host cells, motility, and egress. Plasma membrane Ca2+ entry in T. gondii was previously shown to be activated by cytosolic calcium and inhibited by the voltage-operated Ca2+ channel blocker nifedipine. However, Ca2+ entry in T. gondii did not show the classical characteristics of store regulation. In this work, we characterized the mechanism by which cytosolic Ca2+ regulates plasma membrane Ca2+ entry in extracellular T. gondii tachyzoites loaded with the Ca2+ indicator Fura-2. We compared the inhibition by nifedipine with the effect of the broad spectrum TRP channel inhibitor, anthranilic acid or ACA, and we find that both inhibitors act on different Ca2+ entry activities. We demonstrate, using pharmacological and genetic tools, that an intracellular signaling pathway engaging cyclic GMP, protein kinase G, Ca2+, and the phosphatidyl inositol phospholipase C affects Ca2+ entry and we present a model for crosstalk between cyclic GMP and cytosolic Ca2+ for the activation of T. gondii's lytic cycle traits.
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Affiliation(s)
- Miryam A Hortua Triana
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
| | | | | | - Shannon Quinn
- Department of Computer Science, University of Georgia, Athens, Georgia, USA
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA; Department of Cellular Biology, University of Georgia, Athens, Georgia, USA.
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4
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Shortt E, Hackett CG, Stadler RV, Kent RS, Herneisen AL, Ward GE, Lourido S. CDPK2A and CDPK1 form a signaling module upstream of Toxoplasma motility. mBio 2023; 14:e0135823. [PMID: 37610220 PMCID: PMC10653799 DOI: 10.1128/mbio.01358-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 06/17/2023] [Indexed: 08/24/2023] Open
Abstract
IMPORTANCE This work uncovers interactions between various signaling pathways that govern Toxoplasma gondii egress. Specifically, we compare the function of three canonical calcium-dependent protein kinases (CDPKs) using chemical-genetic and conditional-depletion approaches. We describe the function of a previously uncharacterized CDPK, CDPK2A, in the Toxoplasma lytic cycle, demonstrating that it contributes to parasite fitness through regulation of microneme discharge, gliding motility, and egress from infected host cells. Comparison of analog-sensitive kinase alleles and conditionally depleted alleles uncovered epistasis between CDPK2A and CDPK1, implying a partial functional redundancy. Understanding the topology of signaling pathways underlying key events in the parasite life cycle can aid in efforts targeting kinases for anti-parasitic therapies.
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Affiliation(s)
- Emily Shortt
- Whitehead Institute, Cambridge, Massachusetts, USA
| | | | - Rachel V. Stadler
- Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - Robyn S. Kent
- Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - Alice L. Herneisen
- Whitehead Institute, Cambridge, Massachusetts, USA
- Biology Department, MIT, Cambridge, Massachusetts, USA
| | - Gary E. Ward
- Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - Sebastian Lourido
- Whitehead Institute, Cambridge, Massachusetts, USA
- Biology Department, MIT, Cambridge, Massachusetts, USA
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5
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Arabiotorre A, Bankaitis VA, Grabon A. Regulation of phosphoinositide metabolism in Apicomplexan parasites. Front Cell Dev Biol 2023; 11:1163574. [PMID: 37791074 PMCID: PMC10543664 DOI: 10.3389/fcell.2023.1163574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 07/11/2023] [Indexed: 10/05/2023] Open
Abstract
Phosphoinositides are a biologically essential class of phospholipids that contribute to organelle membrane identity, modulate membrane trafficking pathways, and are central components of major signal transduction pathways that operate on the cytosolic face of intracellular membranes in eukaryotes. Apicomplexans (such as Toxoplasma gondii and Plasmodium spp.) are obligate intracellular parasites that are important causative agents of disease in animals and humans. Recent advances in molecular and cell biology of Apicomplexan parasites reveal important roles for phosphoinositide signaling in key aspects of parasitosis. These include invasion of host cells, intracellular survival and replication, egress from host cells, and extracellular motility. As Apicomplexans have adapted to the organization of essential signaling pathways to accommodate their complex parasitic lifestyle, these organisms offer experimentally tractable systems for studying the evolution, conservation, and repurposing of phosphoinositide signaling. In this review, we describe the regulatory mechanisms that control the spatial and temporal regulation of phosphoinositides in the Apicomplexan parasites Plasmodium and T. gondii. We further discuss the similarities and differences presented by Apicomplexan phosphoinositide signaling relative to how these pathways are regulated in other eukaryotic organisms.
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Affiliation(s)
- Angela Arabiotorre
- Department of Cell Biology and Genetics, College of Medicine Texas A&M Health Sciences Center College Station, Bryan, TX, United States
| | - Vytas A. Bankaitis
- Department of Cell Biology and Genetics, College of Medicine Texas A&M Health Sciences Center College Station, Bryan, TX, United States
- Department of Biochemistry and Biophysics Texas A&M University College Station, College Station, TX, United States
- Department of Chemistry Texas A&M University College Station, College Station, TX, United States
| | - Aby Grabon
- Department of Cell Biology and Genetics, College of Medicine Texas A&M Health Sciences Center College Station, Bryan, TX, United States
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Gong Z, Qu Z, Yu Z, Li J, Liu B, Ma X, Cai J. Label-free quantitative detection and comparative analysis of lysine acetylation during the different life stages of Eimeria tenella. J Proteome Res 2023; 22:2785-2802. [PMID: 37562054 DOI: 10.1021/acs.jproteome.2c00726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Proteome-wide lysine acetylation has been documented in apicomplexan parasite Toxoplasma gondii and Plasmodium falciparum. Here, we conducted the first lysine acetylome in unsporulated oocysts (USO), sporulated 7 h oocysts (SO 7h), sporulated oocysts (SO), sporozoites (S), and the second generation merozoites (SMG) of Eimeria tenella through a 4D label-free quantitative technique. Altogether, 8532 lysine acetylation sites on 2325 proteins were identified in E. tenella, among which 5445 sites on 1493 proteins were quantified. In addition, 557, 339, 478, 248, 241, and 424 differentially expressed proteins were identified in the comparisons SO7h vs USO, SO vs SO7h, SO vs USO, S vs SO, SMG vs S, and USO vs SMG, respectively. The bioinformatics analysis of the acetylome showed that the lysine acetylation is widespread on proteins of diverse functions. Moreover, the dynamic changes of lysine acetylome among E. tenella different life stages revealed significant regulation during the whole process of E. tenella growth and stage conversion. This study provides a beginning for the investigation of the regulate role of lysine acetylation in E. tenella and may provide new strategies for anticoccidiosis drug and vaccine development. Raw data are publicly available at iProX with the data set identifier PXD040368.
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Affiliation(s)
| | - Zigang Qu
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Innovation of Research Program of Gastrointestinal Infection and Mucosal Immunity of Poultry and Pig; Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, People's Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu Province 225009, People's Republic of China
| | - Zhengqing Yu
- College of Animal Science and Technology, Ningxia University, Yinchuan, Ningxia Province 750021, People's Republic of China
| | - Jidong Li
- College of Animal Science and Technology, Ningxia University, Yinchuan, Ningxia Province 750021, People's Republic of China
| | - Baohong Liu
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Innovation of Research Program of Gastrointestinal Infection and Mucosal Immunity of Poultry and Pig; Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, People's Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu Province 225009, People's Republic of China
| | - Xueting Ma
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Innovation of Research Program of Gastrointestinal Infection and Mucosal Immunity of Poultry and Pig; Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, People's Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu Province 225009, People's Republic of China
| | - Jianping Cai
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Innovation of Research Program of Gastrointestinal Infection and Mucosal Immunity of Poultry and Pig; Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, People's Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu Province 225009, People's Republic of China
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Toxoplasma Shelph, a Phosphatase Located in the Parasite Endoplasmic Reticulum, Is Required for Parasite Virulence. mSphere 2022; 7:e0035022. [PMID: 36326242 PMCID: PMC9769683 DOI: 10.1128/msphere.00350-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Toxoplasma gondii is a single-celled parasitic eukaryote that evolved to successfully propagate in any nucleated cell. As with any other eukaryote, its life cycle is regulated by signaling pathways controlled by kinases and phosphatases. T. gondii encodes an atypical bacterial-like phosphatase absent from mammalian genomes, named Shelph, after its first identification in the psychrophilic bacterium Schewanella sp. Here, we demonstrate that Toxoplasma Shelph is an active phosphatase localized in the parasite endoplasmic reticulum. The phenotyping of a shelph knockout (KO) line showed a minor impairment in invasion on human fibroblasts, while the other steps of the parasite lytic cycle were not affected. In contrast with Plasmodium ortholog Shelph1, this invasion deficiency was not correlated with any default in the biogenesis of secretory organelles. However, Shelph-KO parasites displayed a much-pronounced defect in virulence in vivo. These phenotypes could be rescued by genetic complementation, thus supporting an important function for Shelph in the context of a natural infection. IMPORTANCE Toxoplasma gondii belongs to the Apicomplexa phylum, which comprises more than 5,000 species, among which is Plasmodium falciparum, the notorious agent of human malaria. Intriguingly, the Apicomplexa genomes encode at least one phosphatase closely related to the bacterial Schewanella phosphatase, or Shelph. To better understand the importance of these atypical bacterial enzymes in eukaryotic parasites, we undertook the functional characterization of T. gondii Shelph. Our results uncovered its subcellular localization and its enzymatic activity, revealed its subtle involvement during the tachyzoite invasion step of the lytic cycle, and more importantly, highlighted a critical requirement of this phosphatase for parasite propagation in mice. Overall, this study revealed an unexpected role for T. gondii Shelph in the maintenance of parasite virulence in vivo.
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8
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Screening the Toxoplasma kinome with high-throughput tagging identifies a regulator of invasion and egress. Nat Microbiol 2022; 7:868-881. [PMID: 35484233 PMCID: PMC9167752 DOI: 10.1038/s41564-022-01104-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 03/11/2022] [Indexed: 12/26/2022]
Abstract
Protein kinases regulate fundamental aspects of eukaryotic cell biology, making them attractive chemotherapeutic targets in parasites like Plasmodium spp. and Toxoplasma gondii. To systematically examine the parasite kinome, we developed a high-throughput tagging (HiT) strategy to endogenously label protein kinases with an auxin-inducible degron and fluorophore. Hundreds of tagging vectors were assembled from synthetic sequences in a single reaction and used to generate pools of mutants to determine localization and function. Examining 1,160 arrayed clones, we assigned 40 protein localizations and associated 15 kinases with distinct defects. The fitness of tagged alleles was also measured by pooled screening, distinguishing delayed from acute phenotypes. A previously unstudied kinase, associated with delayed loss, was shown to be a regulator of invasion and egress. We named the kinase Store Potentiating/Activating Regulatory Kinase (SPARK), based on its impact on intracellular Ca2+ stores. Despite homology to mammalian PDK1, SPARK lacks a lipid-binding domain, suggesting a rewiring of the pathway in parasites. HiT screening extends genome-wide approaches into complex cellular phenotypes, providing a scalable and versatile platform to dissect parasite biology.
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9
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Huynh MH, Roiko MS, Gomes AO, Schinke EN, Schultz AJ, Agrawal S, Oellig CA, Sexton TR, Beauchamp JM, Laliberté J, Sivaraman KK, Hersh LB, McGowan S, Carruthers VB. Toxoplasma gondii Toxolysin 4 Contributes to Efficient Parasite Egress from Host Cells. mSphere 2021; 6:e0044421. [PMID: 34190588 PMCID: PMC8265663 DOI: 10.1128/msphere.00444-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 06/09/2021] [Indexed: 11/24/2022] Open
Abstract
Egress from host cells is an essential step in the lytic cycle of T. gondii and other apicomplexan parasites; however, only a few parasite secretory proteins are known to affect this process. The putative metalloproteinase toxolysin 4 (TLN4) was previously shown to be an extensively processed microneme protein, but further characterization was impeded by the inability to genetically ablate TLN4. Here, we show that TLN4 has the structural properties of an M16 family metalloproteinase, that it possesses proteolytic activity on a model substrate, and that genetic disruption of TLN4 reduces the efficiency of egress from host cells. Complementation of the knockout strain with the TLN4 coding sequence significantly restored egress competency, affirming that the phenotype of the Δtln4 parasite was due to the absence of TLN4. This work identifies TLN4 as the first metalloproteinase and the second microneme protein to function in T. gondii egress. The study also lays a foundation for future mechanistic studies defining the precise role of TLN4 in parasite exit from host cells. IMPORTANCE After replicating within infected host cells, the single-celled parasite Toxoplasma gondii must rupture out of such cells in a process termed egress. Although it is known that T. gondii egress is an active event that involves disruption of host-derived membranes surrounding the parasite, very few proteins that are released by the parasite are known to facilitate egress. In this study, we identify a parasite secretory protease that is necessary for efficient and timely egress, laying the foundation for understanding precisely how this protease facilitates T. gondii exit from host cells.
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Affiliation(s)
- My-Hang Huynh
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Marijo S. Roiko
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Angelica O. Gomes
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Ellyn N. Schinke
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Aric J. Schultz
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Swati Agrawal
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Christine A. Oellig
- Infection and Immunity Program, Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Travis R. Sexton
- Department of Cardiology, University of Kentucky, Lexington, Kentucky, USA
| | - Jessica M. Beauchamp
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Julie Laliberté
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Komagal Kannan Sivaraman
- Infection and Immunity Program, Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Louis B. Hersh
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, Kentucky, USA
| | - Sheena McGowan
- Infection and Immunity Program, Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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Baker DA, Matralis AN, Osborne SA, Large JM, Penzo M. Targeting the Malaria Parasite cGMP-Dependent Protein Kinase to Develop New Drugs. Front Microbiol 2020; 11:602803. [PMID: 33391223 PMCID: PMC7773720 DOI: 10.3389/fmicb.2020.602803] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/23/2020] [Indexed: 12/17/2022] Open
Abstract
The single-celled apicomplexan parasite Plasmodium falciparum is responsible for the majority of deaths due to malaria each year. The selection of drug resistance has been a recurring theme over the decades with each new drug that is developed. It is therefore crucial that future generations of drugs are explored to tackle this major public health problem. Cyclic GMP (cGMP) signaling is one of the biochemical pathways that is being explored as a potential target for new antimalarial drugs. It has been shown that this pathway is essential for all of the key developmental stages of the complex malaria parasite life cycle. This gives hope that targeting cGMP signaling might give rise to drugs that treat disease, block its transmission and even prevent the establishment of infection. Here we review previous work that has been carried out to develop and optimize inhibitors of the cGMP-dependent protein kinase (PKG) which is a critical regulator of the malaria parasite life cycle.
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Affiliation(s)
- David A Baker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | | | - Simon A Osborne
- LifeArc, Accelerator Building, Open Innovation Campus, Stevenage, United Kingdom
| | - Jonathan M Large
- LifeArc, Accelerator Building, Open Innovation Campus, Stevenage, United Kingdom
| | - Maria Penzo
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
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11
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Herneisen AL, Sidik SM, Markus BM, Drewry DH, Zuercher WJ, Lourido S. Identifying the Target of an Antiparasitic Compound in Toxoplasma Using Thermal Proteome Profiling. ACS Chem Biol 2020; 15:1801-1807. [PMID: 32597628 DOI: 10.1021/acschembio.0c00369] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Apicomplexan parasites include the causative agents of malaria and toxoplasmosis. Cell-based screens in Toxoplasma previously identified a chemical modulator of calcium signaling (ENH1) that blocked parasite egress from host cells and exhibited potent antiparasitic activity. To identify the targets of ENH1, we adapted thermal proteome profiling to Toxoplasma, which revealed calcium-dependent protein kinase 1 (CDPK1) as a target. We confirmed the inhibition of CDPK1 by ENH1 in vitro and in parasites by comparing alleles sensitive or resistant to ENH1. CDPK1 inhibition explained the block in egress; however, the effects of ENH1 on calcium homeostasis and parasite viability were CDPK1-independent, implicating additional targets. Thermal proteome profiling of lysates from parasites expressing the resistant allele of CDPK1 identified additional candidates associated with the mitochondria and the parasite pellicle-compartments that potentially function in calcium release and homeostasis. Our findings illustrate the promise of thermal profiling to identify druggable targets that modulate calcium signaling in apicomplexan parasites.
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Affiliation(s)
- Alice L. Herneisen
- Department of Biology, Massachusetts Institute of Technology, 30 Ames St, Cambridge, Massachusetts 02142, United States
- Whitehead Institute for Biomedical Research, 455 Main St, Cambridge, Massachusetts 02142, United States
| | - Saima M. Sidik
- Whitehead Institute for Biomedical Research, 455 Main St, Cambridge, Massachusetts 02142, United States
| | - Benedikt M. Markus
- Whitehead Institute for Biomedical Research, 455 Main St, Cambridge, Massachusetts 02142, United States
- Faculty of Biology, University of Freiburg, Schänzlestraße 1, Freiburg 79104, Germany
| | - David H. Drewry
- Structural Genomics Consortium, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - William J. Zuercher
- Structural Genomics Consortium, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Sebastian Lourido
- Department of Biology, Massachusetts Institute of Technology, 30 Ames St, Cambridge, Massachusetts 02142, United States
- Whitehead Institute for Biomedical Research, 455 Main St, Cambridge, Massachusetts 02142, United States
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12
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Bisio H, Soldati-Favre D. Signaling Cascades Governing Entry into and Exit from Host Cells by Toxoplasma gondii. Annu Rev Microbiol 2020; 73:579-599. [PMID: 31500539 DOI: 10.1146/annurev-micro-020518-120235] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Apicomplexa phylum includes a large group of obligate intracellular protozoan parasites responsible for important diseases in humans and animals. Toxoplasma gondii is a widespread parasite with considerable versatility, and it is capable of infecting virtually any warm-blooded animal, including humans. This outstanding success can be attributed at least in part to an efficient and continuous sensing of the environment, with a ready-to-adapt strategy. This review updates the current understanding of the signals governing the lytic cycle of T. gondii, with particular focus on egress from infected cells, a key step for balancing survival, multiplication, and spreading in the host. We cover the recent advances in the conceptual framework of regulation of microneme exocytosis that ensures egress, motility, and invasion. Particular emphasis is given to the trigger molecules and signaling cascades regulating exit from host cells.
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Affiliation(s)
- Hugo Bisio
- Département de Microbiologie et Médecine Moléculaire, Centre Médical Universitaire, Université de Genève, 1211 Geneva 4, Switzerland;
| | - Dominique Soldati-Favre
- Département de Microbiologie et Médecine Moléculaire, Centre Médical Universitaire, Université de Genève, 1211 Geneva 4, Switzerland;
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13
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Abstract
Apicomplexans, including species of Eimeria, pose a real threat to the health and wellbeing of animals and humans. Eimeria parasites do not infect humans but cause an important economic impact on livestock, in particular on the poultry industry. Despite its high prevalence and financial costs, little is known about the cell biology of these 'cosmopolitan' parasites found all over the world. In this review, we discuss different aspects of the life cycle and stages of Eimeria species, focusing on cellular structures and organelles typical of the coccidian family as well as genus-specific features, complementing some 'unknowns' with what is described in the closely related coccidian Toxoplasma gondii.
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Structures of the cGMP-dependent protein kinase in malaria parasites reveal a unique structural relay mechanism for activation. Proc Natl Acad Sci U S A 2019; 116:14164-14173. [PMID: 31239348 PMCID: PMC6628679 DOI: 10.1073/pnas.1905558116] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cyclic guanosine-3',5'-monophosphate (cGMP)-dependent protein kinase (PKG) was identified >25 y ago; however, efforts to obtain a structure of the entire PKG enzyme or catalytic domain from any species have failed. In malaria parasites, cooperative activation of PKG triggers crucial developmental transitions throughout the complex life cycle. We have determined the cGMP-free crystallographic structures of PKG from Plasmodium falciparum and Plasmodium vivax, revealing how key structural components, including an N-terminal autoinhibitory segment (AIS), four predicted cyclic nucleotide-binding domains (CNBs), and a kinase domain (KD), are arranged when the enzyme is inactive. The four CNBs and the KD are in a pentagonal configuration, with the AIS docked in the substrate site of the KD in a swapped-domain dimeric arrangement. We show that although the protein is predominantly a monomer (the dimer is unlikely to be representative of the physiological form), the binding of the AIS is necessary to keep Plasmodium PKG inactive. A major feature is a helix serving the dual role of the N-terminal helix of the KD as well as the capping helix of the neighboring CNB. A network of connecting helices between neighboring CNBs contributes to maintaining the kinase in its inactive conformation. We propose a scheme in which cooperative binding of cGMP, beginning at the CNB closest to the KD, transmits conformational changes around the pentagonal molecule in a structural relay mechanism, enabling PKG to orchestrate rapid, highly regulated developmental switches in response to dynamic modulation of cGMP levels in the parasite.
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15
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Günay-Esiyok Ö, Scheib U, Noll M, Gupta N. An unusual and vital protein with guanylate cyclase and P4-ATPase domains in a pathogenic protist. Life Sci Alliance 2019; 2:2/3/e201900402. [PMID: 31235476 PMCID: PMC6592433 DOI: 10.26508/lsa.201900402] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 06/06/2019] [Accepted: 06/06/2019] [Indexed: 12/13/2022] Open
Abstract
Toxoplasma gondii harbors an alveolate-specific guanylate cyclase linked to P-type ATPase motifs, which is an essential actuator of cGMP-dependent gliding motility, egress, and invasion during acute infection. cGMP signaling is one of the master regulators of diverse functions in eukaryotes; however, its architecture and functioning in protozoans remain poorly understood. Herein, we report an exclusive guanylate cyclase coupled with N-terminal P4-ATPase in a common parasitic protist, Toxoplasma gondii. This bulky protein (477-kD), termed TgATPaseP-GC to fairly reflect its envisaged multifunctionality, localizes in the plasma membrane at the apical pole of the parasite, whereas the corresponding cGMP-dependent protein kinase (TgPKG) is distributed in the cytomembranes. TgATPaseP-GC is refractory to genetic deletion, and its CRISPR/Cas9–assisted disruption aborts the lytic cycle of T. gondii. Besides, Cre/loxP–mediated knockdown of TgATPaseP-GC reduced the synthesis of cGMP and inhibited the parasite growth due to impairments in the motility-dependent egress and invasion events. Equally, repression of TgPKG by a similar strategy recapitulated phenotypes of the TgATPaseP-GC–depleted mutant. Notably, despite a temporally restricted function, TgATPaseP-GC is expressed constitutively throughout the lytic cycle, entailing a post-translational regulation of cGMP signaling. Not least, the occurrence of TgATPaseP-GC orthologs in several other alveolates implies a divergent functional repurposing of cGMP signaling in protozoans, and offers an excellent drug target against the parasitic protists.
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Affiliation(s)
- Özlem Günay-Esiyok
- Institute of Biology, Faculty of Life Sciences, Humboldt University, Berlin, Germany
| | - Ulrike Scheib
- Institute of Biology, Faculty of Life Sciences, Humboldt University, Berlin, Germany
| | - Matthias Noll
- Institute of Biology, Faculty of Life Sciences, Humboldt University, Berlin, Germany
| | - Nishith Gupta
- Institute of Biology, Faculty of Life Sciences, Humboldt University, Berlin, Germany
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16
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Bullen HE, Bisio H, Soldati-Favre D. The triumvirate of signaling molecules controlling Toxoplasma microneme exocytosis: Cyclic GMP, calcium, and phosphatidic acid. PLoS Pathog 2019; 15:e1007670. [PMID: 31121005 PMCID: PMC6532924 DOI: 10.1371/journal.ppat.1007670] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
To elicit effective invasion and egress from infected cells, obligate intracellular parasites of the phylum Apicomplexa rely on the timely and spatially controlled exocytosis of specialized secretory organelles termed the micronemes. The effector molecules and signaling events underpinning this process are intricate; however, recent advances within the field of Toxoplasma gondii research have facilitated a broader understanding as well as a more integrated view of this complex cascade of events and have unraveled the importance of phosphatidic acid (PA) as a lipid mediator at multiple steps in this process.
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Affiliation(s)
- Hayley E. Bullen
- Burnet Institute, Melbourne, Victoria, Australia
- * E-mail: (HEB); (DS-F)
| | - Hugo Bisio
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva, Switzerland
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva, Switzerland
- * E-mail: (HEB); (DS-F)
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17
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Tosetti N, Dos Santos Pacheco N, Soldati-Favre D, Jacot D. Three F-actin assembly centers regulate organelle inheritance, cell-cell communication and motility in Toxoplasma gondii. eLife 2019; 8:e42669. [PMID: 30753127 PMCID: PMC6372287 DOI: 10.7554/elife.42669] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 01/29/2019] [Indexed: 01/06/2023] Open
Abstract
Toxoplasma gondii possesses a limited set of actin-regulatory proteins and relies on only three formins (FRMs) to nucleate and polymerize actin. We combined filamentous actin (F-actin) chromobodies with gene disruption to assign specific populations of actin filaments to individual formins. FRM2 localizes to the apical juxtanuclear region and participates in apicoplast inheritance. Restricted to the residual body, FRM3 maintains the intravacuolar cell-cell communication. Conoidal FRM1 initiates a flux of F-actin crucial for motility, invasion and egress. This flux depends on myosins A and H and is controlled by phosphorylation via PKG (protein kinase G) and CDPK1 (calcium-dependent protein kinase 1) and by methylation via AKMT (apical lysine methyltransferase). This flux is independent of microneme secretion and persists in the absence of the glideosome-associated connector (GAC). This study offers a coherent model of the key players controlling actin polymerization, stressing the importance of well-timed post-translational modifications to power parasite motility.
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Affiliation(s)
- Nicolò Tosetti
- Department of Microbiology and Molecular Medicine, CMUUniversity of GenevaGenevaSwitzerland
| | | | | | - Damien Jacot
- Department of Microbiology and Molecular Medicine, CMUUniversity of GenevaGenevaSwitzerland
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18
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Yan M, Cui X, Zhao Q, Zhu S, Huang B, Wang L, Zhao H, Liu G, Li Z, Han H, Dong H. Molecular characterization and protective efficacy of the microneme 2 protein from Eimeria tenella. ACTA ACUST UNITED AC 2018; 25:60. [PMID: 30474601 PMCID: PMC6254105 DOI: 10.1051/parasite/2018061] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 11/12/2018] [Indexed: 11/14/2022]
Abstract
Microneme proteins play an important role in the adherence of apicomplexan parasites to host cells during the invasion process. In this study, the microneme 2 protein from the protozoan parasite Eimeria tenella (EtMIC2) was cloned, characterized, and its protective efficacy as a DNA vaccine investigated. The EtMIC2 gene, which codes for a 35.07 kDa protein in E. tenella sporulated oocysts, was cloned and recombinant EtMIC2 protein (rEtMIC2) was produced in an Escherichia coli expression system. Immunostaining with an anti-rEtMIC2 antibody showed that the EtMIC2 protein mainly localized in the anterior region and membrane of sporozoites, in the cytoplasm of first- and second-generation merozoites, and was strongly expressed during first-stage schizogony. In addition, incubation with specific antibodies against EtMIC2 was found to efficiently reduce the ability of E. tenella sporozoites to invade host cells. Furthermore, animal-challenge experiments demonstrated that immunization with pcDNA3.1(+)-EtMIC2 significantly increased average body weight gain, while decreasing the mean lesion score and oocyst output in chickens. Taken together, these results suggest that EtMIC2 plays an important role in parasite cell invasion and may be a viable candidate for the development of new vaccines against E. tenella infection in chickens.
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Affiliation(s)
- Ming Yan
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China - College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Xiaoxia Cui
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China - Qingdao Yebio Biological Engineering Co., Ltd, Qingdao 266114, PR China
| | - Qiping Zhao
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Shunhai Zhu
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Bing Huang
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Lu Wang
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Huanzhi Zhao
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Guiling Liu
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Zhihang Li
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China - College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Hongyu Han
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Hui Dong
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
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19
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Brown KM, Sibley LD. Essential cGMP Signaling in Toxoplasma Is Initiated by a Hybrid P-Type ATPase-Guanylate Cyclase. Cell Host Microbe 2018; 24:804-816.e6. [PMID: 30449726 DOI: 10.1016/j.chom.2018.10.015] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 08/30/2018] [Accepted: 10/01/2018] [Indexed: 11/28/2022]
Abstract
Apicomplexan parasites rely on cyclic nucleotide-dependent kinases for host cell infection, yet the mechanisms that control their activation remain unknown. Here we show that an apically localized guanylate cyclase (GC) controls microneme secretion and lytic growth in the model apicomplexan Toxoplasma gondii. Cell-permeable cGMP reversed the block in microneme secretion seen in a knockdown of TgGC, linking its function to production of cGMP. TgGC possesses an N-terminal P-type ATPase domain fused to a C-terminal heterodimeric guanylate cyclase domain, an architecture found only in Apicomplexa and related protists. Complementation with a panel of mutants revealed a critical requirement for the P-type ATPase domain for maximum GC function. We further demonstrate that knockdown of TgGC in vivo protects mice from lethal infection by blocking parasite expansion and dissemination. Collectively, this work demonstrates that cGMP-mediated signaling in Toxoplasma relies on a multi-domain architecture, which may serve a conserved role in related parasites.
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Affiliation(s)
- Kevin M Brown
- Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA
| | - L David Sibley
- Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA.
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20
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Hortua Triana MA, Márquez-Nogueras KM, Vella SA, Moreno SNJ. Calcium signaling and the lytic cycle of the Apicomplexan parasite Toxoplasma gondii. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1865:1846-1856. [PMID: 30992126 DOI: 10.1016/j.bbamcr.2018.08.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Revised: 08/06/2018] [Accepted: 08/07/2018] [Indexed: 01/24/2023]
Abstract
Toxoplasma gondii has a complex life cycle involving different hosts and is dependent on fast responses, as the parasite reacts to changing environmental conditions. T. gondii causes disease by lysing the host cells that it infects and it does this by reiterating its lytic cycle, which consists of host cell invasion, replication inside the host cell, and egress causing host cell lysis. Calcium ion (Ca2+) signaling triggers activation of molecules involved in the stimulation and enhancement of each step of the parasite lytic cycle. Ca2+ signaling is essential for the cellular and developmental changes that support T. gondii parasitism. The characterization of the molecular players and pathways directly activated by Ca2+ signaling in Toxoplasma is sketchy and incomplete. The evolutionary distance between Toxoplasma and other eukaryotic model systems makes the comparison sometimes not informative. The advent of new genomic information and new genetic tools applicable for studying Toxoplasma biology is rapidly changing this scenario. The Toxoplasma genome reveals the presence of many genes potentially involved in Ca2+ signaling, even though the role of most of them is not known. The use of Genetically Encoded Calcium Indicators (GECIs) has allowed studies on the role of novel calcium-related proteins on egress, an essential step for the virulence and dissemination of Toxoplasma. In addition, the discovery of new Ca2+ players is generating novel targets for drugs, vaccines, and diagnostic tools and a better understanding of the biology of these parasites.
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Affiliation(s)
| | | | - Stephen A Vella
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA; Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA.
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21
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Baker DA, Drought LG, Flueck C, Nofal SD, Patel A, Penzo M, Walker EM. Cyclic nucleotide signalling in malaria parasites. Open Biol 2018; 7:rsob.170213. [PMID: 29263246 PMCID: PMC5746546 DOI: 10.1098/rsob.170213] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 11/28/2017] [Indexed: 12/22/2022] Open
Abstract
The cyclic nucleotides 3′, 5′-cyclic adenosine monophosphate (cAMP) and 3′, 5′-cyclic guanosine monophosphate (cGMP) are intracellular messengers found in most animal cell types. They usually mediate an extracellular stimulus to drive a change in cell function through activation of their respective cyclic nucleotide-dependent protein kinases, PKA and PKG. The enzymatic components of the malaria parasite cyclic nucleotide signalling pathways have been identified, and the genetic and biochemical studies of these enzymes carried out to date are reviewed herein. What has become very clear is that cyclic nucleotides play vital roles in controlling every stage of the complex malaria parasite life cycle. Our understanding of the involvement of cyclic nucleotide signalling in orchestrating the complex biology of malaria parasites is still in its infancy, but the recent advances in our genetic tools and the increasing interest in signalling will deliver more rapid progress in the coming years.
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Affiliation(s)
- David A Baker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Laura G Drought
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Christian Flueck
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Stephanie D Nofal
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Avnish Patel
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Maria Penzo
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK.,Tres Cantos Medicines Development Campus, Diseases of the Developing World, GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain
| | - Eloise M Walker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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22
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Jia Y, Marq JB, Bisio H, Jacot D, Mueller C, Yu L, Choudhary J, Brochet M, Soldati-Favre D. Crosstalk between PKA and PKG controls pH-dependent host cell egress of Toxoplasma gondii. EMBO J 2017; 36:3250-3267. [PMID: 29030485 PMCID: PMC5666616 DOI: 10.15252/embj.201796794] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 09/08/2017] [Accepted: 09/12/2017] [Indexed: 12/27/2022] Open
Abstract
Toxoplasma gondii encodes three protein kinase A catalytic (PKAc1-3) and one regulatory (PKAr) subunits to integrate cAMP-dependent signals. Here, we show that inactive PKAc1 is maintained at the parasite pellicle by interacting with acylated PKAr. Either a conditional knockdown of PKAr or the overexpression of PKAc1 blocks parasite division. Conversely, down-regulation of PKAc1 or stabilisation of a dominant-negative PKAr isoform that does not bind cAMP triggers premature parasite egress from infected cells followed by serial invasion attempts leading to host cell lysis. This untimely egress depends on host cell acidification. A phosphoproteome analysis suggested the interplay between cAMP and cGMP signalling as PKAc1 inactivation changes the phosphorylation profile of a putative cGMP-phosphodiesterase. Concordantly, inhibition of the cGMP-dependent protein kinase G (PKG) blocks egress induced by PKAc1 inactivation or environmental acidification, while a cGMP-phosphodiesterase inhibitor circumvents egress repression by PKAc1 or pH neutralisation. This indicates that pH and PKAc1 act as balancing regulators of cGMP metabolism to control egress. These results reveal a crosstalk between PKA and PKG pathways to govern egress in T. gondii.
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Affiliation(s)
- Yonggen Jia
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
| | - Jean-Baptiste Marq
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
| | - Hugo Bisio
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
| | - Damien Jacot
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
| | - Christina Mueller
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
| | - Lu Yu
- Proteomic Mass-spectrometry Team, Wellcome Trust Sanger Institute, Hinxton, UK
| | - Jyoti Choudhary
- Proteomic Mass-spectrometry Team, Wellcome Trust Sanger Institute, Hinxton, UK
| | - Mathieu Brochet
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
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23
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Singh S, Chitnis CE. Molecular Signaling Involved in Entry and Exit of Malaria Parasites from Host Erythrocytes. Cold Spring Harb Perspect Med 2017; 7:cshperspect.a026815. [PMID: 28507195 DOI: 10.1101/cshperspect.a026815] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
During the blood stage, Plasmodium spp. merozoites invade host red blood cells (RBCs), multiply, exit, and reinvade uninfected RBCs in a continuing cycle that is responsible for all the clinical symptoms associated with malaria. Entry into (invasion) and exit from (egress) RBCs are highly regulated processes that are mediated by an array of parasite proteins with specific functional roles. Many of these parasite proteins are stored in specialized apical secretory vesicles, and their timely release is critical for successful invasion and egress. For example, the discharge of parasite protein ligands to the apical surface of merozoites is required for interaction with host receptors to mediate invasion, and the timely discharge of proteases and pore-forming proteins helps in permeabilization and dismantling of limiting membranes during egress. This review focuses on our understanding of the signaling mechanisms that regulate apical organelle secretion during host cell invasion and egress by malaria parasites. The review also explores how understanding key signaling mechanisms in the parasite can open opportunities to develop novel strategies to target Plasmodium parasites and eliminate malaria.
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Affiliation(s)
- Shailja Singh
- Department of Parasites and Insect Vectors, Institut Pasteur, 75015 Paris, France.,Shiv Nadar University, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Chetan E Chitnis
- Department of Parasites and Insect Vectors, Institut Pasteur, 75015 Paris, France.,Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi 110067, India
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24
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AID-ing Signaling in Toxoplasma gondii. mBio 2017; 8:mBio.01076-17. [PMID: 28743818 PMCID: PMC5527314 DOI: 10.1128/mbio.01076-17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The cyclic GMP-dependent protein kinase (PKG) of apicomplexan parasites is essential for secretion of micronemes and host cell invasion and egress. Both kinase specificity and localization can determine which substrates are phosphorylated. The functions of plasma membrane and cytosolic PKG isoforms of Toxoplasma gondii were unknown because of difficulties precisely manipulating expression of essential genes. Brown et al. (K. M. Brown, S. Long, and L. D. Sibley, mBio 8:e00375-17, https://doi.org/10.1128/mBio.00375-17) adapted the auxin-inducible degron (AID) system for conditional expression of T. gondii proteins. AID, in combination with clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 gene editing, facilitated creation of a panel of PKG mutants to demonstrate that the membrane association via acylation of PKG is critical for its essential functions in tachyzoites. The cytosolic form of PKG is not sufficient for viability and is dispensable. These studies illuminate a critical role for targeting of kinase complexes for parasite viability. The AID system enables rapid, conditional regulation of protein expression that expands the molecular toolbox of T. gondii.
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25
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Marugan-Hernandez V, Long E, Blake D, Crouch C, Tomley F. Eimeria tenella protein trafficking: differential regulation of secretion versus surface tethering during the life cycle. Sci Rep 2017; 7:4557. [PMID: 28676667 PMCID: PMC5496917 DOI: 10.1038/s41598-017-04049-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 05/08/2017] [Indexed: 01/15/2023] Open
Abstract
Eimeria spp. are intracellular parasites that have a major impact on poultry. Effective live vaccines are available and the development of reverse genetic technologies has raised the prospect of using Eimeria spp. as recombinant vectors to express additional immunoprotective antigens. To study the ability of Eimeria to secrete foreign antigens or display them on the surface of the sporozoite, transiently transfected populations of E. tenella expressing the fluorescent protein mCherry, linked to endogenous signal peptide (SP) and glycophosphatidylinositol-anchor (GPI) sequences, were examined. The SP from microneme protein EtMIC2 (SP2) allowed efficient trafficking of mCherry to cytoplasmic vesicles and following the C-terminal addition of a GPI-anchor (from surface antigen EtSAG1) mCherry was expressed on the sporozoite surface. In stable transgenic populations, mCherry fused to SP2 was secreted into the sporocyst cavity of the oocysts and after excystation, secretion was detected in culture supernatants but not into the parasitophorous vacuole after invasion. When the GPI was incorporated, mCherry was observed on the sporozites surface and in the supernatant of invading sporozoites. The proven secretion and surface exposure of mCherry suggests that antigen fusions with SP2 and GPI of EtSAG1 may be promising candidates to examine induction of protective immunity against heterologous pathogens.
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Affiliation(s)
- V Marugan-Hernandez
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, AL9 7TA, UK.
| | - E Long
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, AL9 7TA, UK
| | - D Blake
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, AL9 7TA, UK
| | - C Crouch
- MSD Animal Health, Walton Manor, Milton Keynes, MK7 7AJ, UK
| | - F Tomley
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, AL9 7TA, UK
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26
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Abstract
Cyclic GMP (cGMP)-dependent protein kinase (protein kinase G [PKG]) is essential for microneme secretion, motility, invasion, and egress in apicomplexan parasites, However, the separate roles of two isoforms of the kinase that are expressed by some apicomplexans remain uncertain. Despite having identical regulatory and catalytic domains, PKGI is plasma membrane associated whereas PKGII is cytosolic in Toxoplasma gondii. To determine whether these isoforms are functionally distinct or redundant, we developed an auxin-inducible degron (AID) tagging system for conditional protein depletion in T. gondii. By combining AID regulation with genome editing strategies, we determined that PKGI is necessary and fully sufficient for PKG-dependent cellular processes. Conversely, PKGII is functionally insufficient and dispensable in the presence of PKGI. The difference in functionality mapped to the first 15 residues of PKGI, containing a myristoylated Gly residue at position 2 that is critical for membrane association and PKG function. Collectively, we have identified a novel requirement for cGMP signaling at the plasma membrane and developed a new system for examining essential proteins in T. gondii. Toxoplasma gondii is an obligate intracellular apicomplexan parasite and important clinical and veterinary pathogen that causes toxoplasmosis. Since apicomplexans can only propagate within host cells, efficient invasion is critically important for their life cycles. Previous studies using chemical genetics demonstrated that cyclic GMP signaling through protein kinase G (PKG)-controlled invasion by apicomplexan parasites. However, these studies did not resolve functional differences between two compartmentalized isoforms of the kinase. Here we developed a conditional protein regulation tool to interrogate PKG isoforms in T. gondii. We found that the cytosolic PKG isoform was largely insufficient and dispensable. In contrast, the plasma membrane-associated isoform was necessary and fully sufficient for PKG function. Our studies identify the plasma membrane as a key location for PKG activity and provide a broadly applicable system for examining essential proteins in T. gondii.
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27
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Stewart RJ, Whitehead L, Nijagal B, Sleebs BE, Lessene G, McConville MJ, Rogers KL, Tonkin CJ. Analysis of Ca 2+ mediated signaling regulating Toxoplasma infectivity reveals complex relationships between key molecules. Cell Microbiol 2017; 19. [PMID: 27781359 DOI: 10.1111/cmi.12685] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 10/14/2016] [Indexed: 12/28/2022]
Abstract
Host cell invasion, exit and parasite dissemination is critical to the pathogenesis of apicomplexan parasites such as Toxoplasma gondii and Plasmodium spp. These processes are regulated by intracellular Ca2+ signaling although the temporal dynamics of Ca2+ fluxes and down-stream second messenger pathways are poorly understood. Here, we use a genetically encoded biosensor, GFP-Calmodulin-M13-6 (GCaMP6), to capture Ca2+ flux in live Toxoplasma and investigate the role of Ca2+ signaling in egress and motility. Our analysis determines how environmental cues and signal activation influence intracellular Ca2+ flux, allowing placement of effector molecules within this pathway. Importantly, we have identified key interrelationships between cGMP and Ca2+ signaling that are required for activation of egress and motility. Furthermore, we extend this analysis to show that the Ca2+ Dependent Protein Kinases-TgCDPK1 and TgCDPK3-play a role in signal quenching before egress. This work highlights the interrelationships of second messenger pathways of Toxoplasma in space and time, which is likely required for pathogenesis of all apicomplexan species.
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Affiliation(s)
- Rebecca J Stewart
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Lachlan Whitehead
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Brunda Nijagal
- Metabolomics Australia, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Brad E Sleebs
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Guillaume Lessene
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia.,Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Malcolm J McConville
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Australia
| | - Kelly L Rogers
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Christopher J Tonkin
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia
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28
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Phosphatidic Acid-Mediated Signaling Regulates Microneme Secretion in Toxoplasma. Cell Host Microbe 2016; 19:349-60. [PMID: 26962945 DOI: 10.1016/j.chom.2016.02.006] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 09/28/2015] [Accepted: 02/17/2016] [Indexed: 11/24/2022]
Abstract
The obligate intracellular lifestyle of apicomplexan parasites necessitates an invasive phase underpinned by timely and spatially controlled secretion of apical organelles termed micronemes. In Toxoplasma gondii, extracellular potassium levels and other stimuli trigger a signaling cascade culminating in phosphoinositide-phospholipase C (PLC) activation, which generates the second messengers diacylglycerol (DAG) and IP3 and ultimately results in microneme secretion. Here we show that a delicate balance between DAG and its downstream product, phosphatidic acid (PA), is essential for controlling microneme release. Governing this balance is the apicomplexan-specific DAG-kinase-1, which interconverts PA and DAG, and whose depletion impairs egress and causes parasite death. Additionally, we identify an acylated pleckstrin-homology (PH) domain-containing protein (APH) on the microneme surface that senses PA during microneme secretion and is necessary for microneme exocytosis. As APH is conserved in Apicomplexa, these findings highlight a potentially widely used mechanism in which key lipid mediators regulate microneme exocytosis.
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29
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Review of Experimental Compounds Demonstrating Anti-Toxoplasma Activity. Antimicrob Agents Chemother 2016; 60:7017-7034. [PMID: 27600037 DOI: 10.1128/aac.01176-16] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Toxoplasma gondii is a ubiquitous apicomplexan parasite capable of infecting humans and other animals. Current treatment options for T. gondii infection are limited and most have drawbacks, including high toxicity and low tolerability. Additionally, no FDA-approved treatments are available for pregnant women, a high-risk population due to transplacental infection. Therefore, the development of novel treatment options is needed. To aid this effort, this review highlights experimental compounds that, at a minimum, demonstrate inhibition of in vitro growth of T. gondii When available, host cell toxicity and in vivo data are also discussed. The purpose of this review is to facilitate additional development of anti-Toxoplasma compounds and potentially to extend our knowledge of the parasite.
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30
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Govindasamy K, Jebiwott S, Jaijyan DK, Davidow A, Ojo KK, Van Voorhis WC, Brochet M, Billker O, Bhanot P. Invasion of hepatocytes by Plasmodium sporozoites requires cGMP-dependent protein kinase and calcium dependent protein kinase 4. Mol Microbiol 2016; 102:349-363. [PMID: 27425827 DOI: 10.1111/mmi.13466] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2016] [Indexed: 01/24/2023]
Abstract
Invasion of hepatocytes by sporozoites is essential for Plasmodium to initiate infection of the mammalian host. The parasite's subsequent intracellular differentiation in the liver is the first developmental step of its mammalian cycle. Despite their biological significance, surprisingly little is known of the signalling pathways required for sporozoite invasion. We report that sporozoite invasion of hepatocytes requires signalling through two second-messengers - cGMP mediated by the parasite's cGMP-dependent protein kinase (PKG), and Ca2+ , mediated by the parasite's calcium-dependent protein kinase 4 (CDPK4). Sporozoites expressing a mutated form of Plasmodium berghei PKG or carrying a deletion of the CDPK4 gene are defective in invasion of hepatocytes. Using specific and potent inhibitors of Plasmodium PKG and CDPK4, we demonstrate that PKG and CDPK4 are required for sporozoite motility, and that PKG regulates the secretion of TRAP, an adhesin that is essential for motility. Chemical inhibition of PKG decreases parasite egress from hepatocytes by inhibiting either the formation or release of merosomes. In contrast, genetic inhibition of CDPK4 does not significantly decrease the number of merosomes. By revealing the requirement for PKG and CDPK4 in Plasmodium sporozoite invasion, our work enables a better understanding of kinase pathways that act in different Plasmodium stages.
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Affiliation(s)
- K Govindasamy
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers - New Jersey Medical School, Newark, NJ, USA
| | - S Jebiwott
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers - New Jersey Medical School, Newark, NJ, USA
| | - D K Jaijyan
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers - New Jersey Medical School, Newark, NJ, USA
| | - A Davidow
- Department of Biostatistics, Rutgers - School of Public Health, Newark, NJ, USA
| | - K K Ojo
- Division of Allergy and Infectious Diseases, Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - W C Van Voorhis
- Division of Allergy and Infectious Diseases, Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - M Brochet
- CNRS UMR5235 -Université Montpellier 2, 34095, Montpellier, France.,University of Geneva, Faculty of Medicine, Department of Microbiology and Molecular Medicine, Switzerland
| | - O Billker
- Wellcome Trust Sanger Institute, Malaria Programme, CB10 1SA, Hinxton, UK
| | - P Bhanot
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers - New Jersey Medical School, Newark, NJ, USA.
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31
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Bullen HE, Soldati-Favre D. A central role for phosphatidic acid as a lipid mediator of regulated exocytosis in apicomplexa. FEBS Lett 2016; 590:2469-81. [PMID: 27403735 DOI: 10.1002/1873-3468.12296] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 07/10/2016] [Accepted: 07/11/2016] [Indexed: 11/08/2022]
Abstract
Lipids are commonly known for the structural roles they play, however, the specific contribution of different lipid classes to wide-ranging signalling pathways is progressively being unravelled. Signalling lipids and their associated effector proteins are emerging as significant contributors to a vast array of effector functions within cells, including essential processes such as membrane fusion and vesicle exocytosis. Many phospholipids have signalling capacity, however, this review will focus on phosphatidic acid (PA) and the enzymes implicated in its production from diacylglycerol (DAG) and phosphatidylcholine (PC): DGK and PLD respectively. PA is a negatively charged, cone-shaped lipid identified as a key mediator in specific membrane fusion and vesicle exocytosis events in a variety of mammalian cells, and has recently been implicated in specialised secretory organelle exocytosis in apicomplexan parasites. This review summarises the recent work implicating a role for PA regulation in exocytosis in various cell types. We will discuss how these signalling events are linked to pathogenesis in the phylum Apicomplexa.
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32
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Chakraborty A. Emerging drug resistance in Plasmodium falciparum: A review of well-characterized drug targets for novel antimalarial chemotherapy. ASIAN PACIFIC JOURNAL OF TROPICAL DISEASE 2016. [DOI: 10.1016/s2222-1808(16)61090-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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33
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Analysis of Noncanonical Calcium-Dependent Protein Kinases in Toxoplasma gondii by Targeted Gene Deletion Using CRISPR/Cas9. Infect Immun 2016; 84:1262-1273. [PMID: 26755159 DOI: 10.1128/iai.01173-15] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 01/04/2016] [Indexed: 12/31/2022] Open
Abstract
Calcium-dependent protein kinases (CDPKs) are expanded in apicomplexan parasites, especially in Toxoplasma gondii where 14 separate genes encoding these enzymes are found. Although previous studies have shown that several CDPKs play a role in controlling invasion, egress, and cell division in T. gondii, the roles of most of these genes are unexplored. Here we developed a more efficient method for gene disruption using CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 (CRISPR-associated protein 9) that was modified to completely delete large, multiexonic genes from the genome and to allow serial replacement by recycling of the selectable marker using Cre-loxP. Using this system, we generated a total of 24 mutants in type 1 and 2 genetic backgrounds to ascertain the functions of noncanonical CDPKs. Remarkably, although we were able to confirm the essentiality of CDPK1 and CDPK7, the majority of CDPKs had no discernible phenotype for growth in vitro or infection in the mouse model. The exception to this was CDPK6, loss of which leads to reduced plaquing, fitness defect in a competition assay, and reduced tissue cyst formation in chronically infected mice. Our findings highlight the utility of CRISPR/Cas9 for rapid serial gene deletion and also suggest that additional models are needed to reveal the functions of many genes in T. gondii.
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34
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Sidik SM, Hortua Triana MA, Paul AS, El Bakkouri M, Hackett CG, Tran F, Westwood NJ, Hui R, Zuercher WJ, Duraisingh MT, Moreno SNJ, Lourido S. Using a Genetically Encoded Sensor to Identify Inhibitors of Toxoplasma gondii Ca2+ Signaling. J Biol Chem 2016; 291:9566-80. [PMID: 26933036 PMCID: PMC4850295 DOI: 10.1074/jbc.m115.703546] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Indexed: 11/27/2022] Open
Abstract
The life cycles of apicomplexan parasites progress in accordance with fluxes in cytosolic Ca2+. Such fluxes are necessary for events like motility and egress from host cells. We used genetically encoded Ca2+ indicators (GCaMPs) to develop a cell-based phenotypic screen for compounds that modulate Ca2+ signaling in the model apicomplexan Toxoplasma gondii. In doing so, we took advantage of the phosphodiesterase inhibitor zaprinast, which we show acts in part through cGMP-dependent protein kinase (protein kinase G; PKG) to raise levels of cytosolic Ca2+. We define the pool of Ca2+ regulated by PKG to be a neutral store distinct from the endoplasmic reticulum. Screening a library of 823 ATP mimetics, we identify both inhibitors and enhancers of Ca2+ signaling. Two such compounds constitute novel PKG inhibitors and prevent zaprinast from increasing cytosolic Ca2+. The enhancers identified are capable of releasing intracellular Ca2+ stores independently of zaprinast or PKG. One of these enhancers blocks parasite egress and invasion and shows strong antiparasitic activity against T. gondii. The same compound inhibits invasion of the most lethal malaria parasite, Plasmodium falciparum. Inhibition of Ca2+-related phenotypes in these two apicomplexan parasites suggests that depletion of intracellular Ca2+ stores by the enhancer may be an effective antiparasitic strategy. These results establish a powerful new strategy for identifying compounds that modulate the essential parasite signaling pathways regulated by Ca2+, underscoring the importance of these pathways and the therapeutic potential of their inhibition.
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Affiliation(s)
- Saima M Sidik
- From the Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142
| | - Miryam A Hortua Triana
- the Center for Tropical and Emerging Global Diseases, Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Aditya S Paul
- the Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115
| | - Majida El Bakkouri
- the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Caroline G Hackett
- From the Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142
| | - Fanny Tran
- the School of Chemistry and Biomedical Sciences Research Complex, University of St. Andrews and EaStCHEM, North Haugh, St. Andrews, Fife KY16 9ST, Scotland, United Kingdom, and
| | - Nicholas J Westwood
- the School of Chemistry and Biomedical Sciences Research Complex, University of St. Andrews and EaStCHEM, North Haugh, St. Andrews, Fife KY16 9ST, Scotland, United Kingdom, and
| | - Raymond Hui
- the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - William J Zuercher
- the Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Manoj T Duraisingh
- the Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115
| | - Silvia N J Moreno
- the Center for Tropical and Emerging Global Diseases, Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Sebastian Lourido
- From the Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142,
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35
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Brown KM, Lourido S, Sibley LD. Serum Albumin Stimulates Protein Kinase G-dependent Microneme Secretion in Toxoplasma gondii. J Biol Chem 2016; 291:9554-65. [PMID: 26933037 DOI: 10.1074/jbc.m115.700518] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Indexed: 11/06/2022] Open
Abstract
Microneme secretion is essential for motility, invasion, and egress in apicomplexan parasites. Although previous studies indicate that Ca(2+) and cGMP control microneme secretion, little is known about how these pathways are naturally activated. Here we have developed genetically encoded indicators for Ca(2+) and microneme secretion to better define the signaling pathways that regulate these processes in Toxoplasma gondii We found that microneme secretion was triggered in vitro by exposure to a single host protein, serum albumin. The natural agonist serum albumin induced microneme secretion in a protein kinase G-dependent manner that correlated with increased cGMP levels. Surprisingly, serum albumin acted independently of elevated Ca(2+) and yet it was augmented by artificial agonists that raise Ca(2+), such as ethanol. Furthermore, although ethanol elevated intracellular Ca(2+), it alone was unable to trigger secretion without the presence of serum or serum albumin. This dichotomy was recapitulated by zaprinast, a phosphodiesterase inhibitor that elevated cGMP and separately increased Ca(2+) in a protein kinase G-independent manner leading to microneme secretion. Taken together, these findings reveal that microneme secretion is centrally controlled by protein kinase G and that this pathway is further augmented by elevation of intracellular Ca(2.)
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Affiliation(s)
- Kevin M Brown
- From the Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Sebastian Lourido
- From the Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - L David Sibley
- From the Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110
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36
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Graindorge A, Frénal K, Jacot D, Salamun J, Marq JB, Soldati-Favre D. The Conoid Associated Motor MyoH Is Indispensable for Toxoplasma gondii Entry and Exit from Host Cells. PLoS Pathog 2016; 12:e1005388. [PMID: 26760042 PMCID: PMC4711953 DOI: 10.1371/journal.ppat.1005388] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 12/17/2015] [Indexed: 11/23/2022] Open
Abstract
Many members of the phylum of Apicomplexa have adopted an obligate intracellular life style and critically depend on active invasion and egress from the infected cells to complete their lytic cycle. Toxoplasma gondii belongs to the coccidian subgroup of the Apicomplexa, and as such, the invasive tachyzoite contains an organelle termed the conoid at its extreme apex. This motile organelle consists of a unique polymer of tubulin fibres and protrudes in both gliding and invading parasites. The class XIV myosin A, which is conserved across the Apicomplexa phylum, is known to critically contribute to motility, invasion and egress from infected cells. The MyoA-glideosome is anchored to the inner membrane complex (IMC) and is assumed to translocate the components of the circular junction secreted by the micronemes and rhoptries, to the rear of the parasite. Here we comprehensively characterise the class XIV myosin H (MyoH) and its associated light chains. We show that the 3 alpha-tubulin suppressor domains, located in MyoH tail, are necessary to anchor this motor to the conoid. Despite the presence of an intact MyoA-glideosome, conditional disruption of TgMyoH severely compromises parasite motility, invasion and egress from infected cells. We demonstrate that MyoH is necessary for the translocation of the circular junction from the tip of the parasite, where secretory organelles exocytosis occurs, to the apical position where the IMC starts. This study attributes for the first time a direct function of the conoid in motility and invasion, and establishes the indispensable role of MyoH in initiating the first step of motility along this unique organelle, which is subsequently relayed by MyoA to enact effective gliding and invasion. The Apicomplexa phylum groups important pathogens that infect humans and animals. Host cell invasion and egress from infected cells are key events in the lytic cycle of these obligate intracellular parasites. Host cell entry is powered by gliding motility and initiated by the discharge of apical secretory organelles at the site of contact with the host cell. Anchored to the parasite pellicle, the glideosome composed of myosin A and the gliding associated proteins is the molecular machine which translocates the secreted adhesins from the apical to the posterior pole of the parasite and hence propels the parasite into the host cell. Toxoplasma gondii exhibits a helical form of gliding motility and as member of the coccidian-subgroup of Apicomplexa possesses an apical organelle called the conoid, which protrudes during invasion and egress and consists in helically organized polymer of tubulin fibers. We have deciphered here the function of a novel myosin associated to the microtubules composing the conoid. Myosin H is essential and prerequisite for motility, invasion and egress from infected cells. This unusual motor links actin- and tubulin-based cytoskeletons and uncovers a direct role of the conoid in motility and invasion.
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Affiliation(s)
- Arnault Graindorge
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Karine Frénal
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Damien Jacot
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Julien Salamun
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Jean Baptiste Marq
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- * E-mail:
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37
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Okombo J, Chibale K. Antiplasmodial drug targets: a patent review (2000 – 2013). Expert Opin Ther Pat 2015; 26:107-30. [DOI: 10.1517/13543776.2016.1113258] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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38
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Inhibition of Calcium-Dependent Protein Kinase 1 (CDPK1) In Vitro by Pyrazolopyrimidine Derivatives Does Not Correlate with Sensitivity of Cryptosporidium parvum Growth in Cell Culture. Antimicrob Agents Chemother 2015; 60:570-9. [PMID: 26552986 DOI: 10.1128/aac.01915-15] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Accepted: 11/06/2015] [Indexed: 11/20/2022] Open
Abstract
Cryptosporidiosis is a serious diarrheal disease in immunocompromised patients and malnourished children, and treatment is complicated by a lack of adequate drugs. Recent studies suggest that the natural occurrence of a small gatekeeper residue in serine threonine calcium-dependent protein kinase 1 (CDPK1) of Cryptosporidium parvum might be exploited to target this enzyme and block parasite growth. Here were explored the potency with which a series of pyrazolopyrimidine analogs, which are selective for small gatekeeper kinases, inhibit C. parvum CDPK1 and block C. parvum growth in tissue culture in vitro. Although these compounds potently inhibited kinase activity in vitro, most had no effect on parasite growth. Moreover, among those that were active against parasite growth, there was a very poor correlation with their 50% inhibitory concentrations against the enzyme. Active compounds also had no effect on cell invasion, unlike the situation in Toxoplasma gondii, where these compounds block CDPK1, prevent microneme secretion, and disrupt cell invasion. These findings suggest that CPDK1 is not essential for C. parvum host cell invasion or growth and therefore that it is not the optimal target for therapeutic intervention. Nonetheless, several inhibitors with low micromolar 50% effective concentrations were identified, and these may affect other essential targets in C. parvum that are worthy of further exploration.
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39
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Chen P, Lv J, Zhang J, Sun H, Chen Z, Li H, Wang F, Zhao X. Evaluation of immune protective efficacies of Eimeria tenella EtMic1 polypeptides with different domain recombination displayed on yeast surface. Exp Parasitol 2015; 155:1-7. [DOI: 10.1016/j.exppara.2015.04.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 02/04/2015] [Accepted: 04/27/2015] [Indexed: 11/30/2022]
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40
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Mitcheson DF, Tobin AB, Alam MM. Applying chemical genetic tools to the study of phospho-signalling pathways in malaria parasites. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1650-6. [PMID: 26143498 DOI: 10.1016/j.bbapap.2015.06.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/25/2015] [Accepted: 06/30/2015] [Indexed: 12/27/2022]
Abstract
Until very recently there has been very little information about the phospho-signalling pathways in apicomplexan parasites including the most virulent species of human malaria parasite, Plasmodium falciparum. With the advancement of mass spectrometry-based phosphoproteomics and the development of chemical genetic approaches to target specific parasite protein kinases, the complexity of the essential role played by phosphorylation in maintaining the viability of apicomplexan parasites is now being revealed. This review will describe these recent advances and will discuss how these approaches can be used to validate parasite protein kinases as drug targets and to determine the on- and off-target action of protein kinase inhibitors. This article is part of a Special Issue entitled: Inhibitors of Protein Kinases.
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Affiliation(s)
- Deborah F Mitcheson
- Department of Cell Physiology and Pharmacology, University of Leicester, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK
| | - Andrew B Tobin
- MRC Toxicology Unit, University of Leicester, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK
| | - Mahmood M Alam
- MRC Toxicology Unit, University of Leicester, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK.
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41
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Hui R, El Bakkouri M, Sibley LD. Designing selective inhibitors for calcium-dependent protein kinases in apicomplexans. Trends Pharmacol Sci 2015; 36:452-60. [PMID: 26002073 DOI: 10.1016/j.tips.2015.04.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 04/17/2015] [Accepted: 04/23/2015] [Indexed: 12/21/2022]
Abstract
Apicomplexan parasites cause some of the most severe human diseases, including malaria (caused by Plasmodium), toxoplasmosis, and cryptosporidiosis. Treatments are limited by the lack of effective drugs and development of resistance to available agents. By exploiting novel features of protein kinases in these parasites, it may be possible to develop new treatments. We summarize here recent advances in identifying small molecule inhibitors against a novel family of plant-like, calcium-dependent kinases that are uniquely expanded in apicomplexan parasites. Analysis of the 3D structure, activation mechanism, and sensitivity to small molecules had identified several attractive chemical scaffolds that are potent and selective inhibitors of these parasite kinases. Further optimization of these leads may yield promising new drugs for treatment of these parasitic infections.
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Affiliation(s)
- Raymond Hui
- Structural Genomics Consortium, University of Toronto, MaRS South Tower, 101 College St, Toronto, ON, M5G 1L7, Canada; Toronto General Hospital Research Institute, 610 University Avenue, Toronto, ON, M5G 2M9, Canada
| | - Majida El Bakkouri
- Structural Genomics Consortium, University of Toronto, MaRS South Tower, 101 College St, Toronto, ON, M5G 1L7, Canada
| | - L David Sibley
- Department of Molecular Microbiology, 660 S. Euclid Ave., Washington University School of Medicine, St Louis, MO 63130, USA.
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42
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Howard BL, Harvey KL, Stewart RJ, Azevedo MF, Crabb BS, Jennings IG, Sanders PR, Manallack DT, Thompson PE, Tonkin CJ, Gilson PR. Identification of potent phosphodiesterase inhibitors that demonstrate cyclic nucleotide-dependent functions in apicomplexan parasites. ACS Chem Biol 2015; 10:1145-54. [PMID: 25555060 DOI: 10.1021/cb501004q] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Apicomplexan parasites, including Plasmodium falciparum and Toxoplasma gondii, the causative agents of severe malaria and toxoplasmosis, respectively, undergo several critical developmental transitions during their lifecycle. Most important for human pathogenesis is the asexual cycle, in which parasites undergo rounds of host cell invasion, replication, and egress (exit), destroying host cell tissue in the process. Previous work has identified important roles for Protein Kinase G (PKG) and Protein Kinase A (PKA) in parasite egress and invasion, yet little is understood about the regulation of cyclic nucleotides, cGMP and cAMP, that activate these enzymes. To address this, we have focused upon the development of inhibitors of 3',5'-cyclic nucleotide phosphodiesterases (PDEs) to block the breakdown of cyclic nucleotides. This was done by repurposing human PDE inhibitors noting various similarities of the human and apicomplexan PDE binding sites. The most potent inhibitors blocked the in vitro proliferation of P. falciparum and T. gondii more potently than the benchmark compound zaprinast. 5-Benzyl-3-isopropyl-1H-pyrazolo[4,3-d]pyrimidin-7(6H)-one (BIPPO) was found to be a potent inhibitor of recombinant P. falciparum PfPDEα and activated PKG-dependent egress of T. gondii and P. falciparum, likely by promoting the exocytosis of micronemes, an activity that was reversed by a specific Protein Kinase G inhibitor. BIPPO also promotes cAMP-dependent phosphorylation of a P. falciparum ligand critical for host cell invasion, suggesting that the compound inhibits single or multiple PDE isoforms that regulate both cGMP and cAMP levels. BIPPO is therefore a useful tool for the dissection of signal transduction pathways in apicomplexan parasites.
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Affiliation(s)
- Brittany L. Howard
- Monash
Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Katherine L. Harvey
- Macfarlane Burnet Institute, Melbourne, Victoria, Australia
- University of Melbourne, Melbourne, Victoria, Australia
| | - Rebecca J. Stewart
- The Walter & Eliza Hall Institute, Melbourne, Victoria, Australia
- Department
of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | | | - Brendan S. Crabb
- Monash
Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Macfarlane Burnet Institute, Melbourne, Victoria, Australia
- University of Melbourne, Melbourne, Victoria, Australia
| | - Ian G. Jennings
- Monash
Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | | | - David T. Manallack
- Monash
Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Philip E. Thompson
- Monash
Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Christopher J. Tonkin
- The Walter & Eliza Hall Institute, Melbourne, Victoria, Australia
- Department
of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Paul R. Gilson
- Monash
Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Macfarlane Burnet Institute, Melbourne, Victoria, Australia
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Molecular characterization and functional analysis of subunit 7 of eukaryotic initiation factor 3 from Eimeria tenella. Exp Parasitol 2015; 154:118-26. [PMID: 25888243 DOI: 10.1016/j.exppara.2015.04.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 03/22/2015] [Accepted: 04/08/2015] [Indexed: 01/27/2023]
Abstract
The initiation of translation in eukaryotic cells is stimulated by proteins known as initiation factors (eIFs). A structurally complex eIF composed of multiple subunits, eIF3 has been shown to have various functions in translation in a variety of eukaryotes. Until now, little is known about eIF3 in Eimeria tenella. Based on a previously identified expressed sequence tag(EST), we cloned the eIF3 subunit 7 gene (EteIF3s7) from E. tenella by rapid amplification of the cDNA ends(RACE). The 2278-bp full-length complementary DNA of EteIF3s7 contained a 1716-bp open reading frame (ORF) that encoded a 571-amino acid (aa) polypeptide. The EteIF3s7 protein contained the subunit 7 domain that is characteristic of members of the eIF3 zeta superfamily. The levels of EteIF3s7 messenger RNA and protein were higher in second generation merozoites than in sporulated oocysts, unsporulated oocysts, or sporozoites, and the EteIF3s7 protein was barely detectable in unsporulated oocysts. Our immunofluorescence analysis showed that the EteIF3s7 protein was uniformly distributed throughout the cytoplasm of sporozoites. After sporozoites were incubated in complete medium, the EteIF3s7 protein localized to the anterior region of the parasite. Following the first schizogenous division, the protein was uniformly dispersed in trophozoites, immature schizonts, and mature schizonts, and the EteIF3s7 protein was observed to be closely associated with the parasitophorous vacuole membrane. An anti-rEteIF3s7 polyclonal antibody inhibited the ability of E. tenella to invade DF-1 cells, which suggested that EteIF3s7 might be involved in host cell invasion and required for the growth of the parasite in the host.
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Odell AV, Tran F, Foderaro JE, Poupart S, Pathak R, Westwood NJ, Ward GE. Yeast three-hybrid screen identifies TgBRADIN/GRA24 as a negative regulator of Toxoplasma gondii bradyzoite differentiation. PLoS One 2015; 10:e0120331. [PMID: 25789621 PMCID: PMC4366382 DOI: 10.1371/journal.pone.0120331] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 02/06/2015] [Indexed: 12/17/2022] Open
Abstract
Differentiation of the protozoan parasite Toxoplasma gondii into its latent bradyzoite stage is a key event in the parasite's life cycle. Compound 2 is an imidazopyridine that was previously shown to inhibit the parasite lytic cycle, in part through inhibition of parasite cGMP-dependent protein kinase. We show here that Compound 2 can also enhance parasite differentiation, and we use yeast three-hybrid analysis to identify TgBRADIN/GRA24 as a parasite protein that interacts directly or indirectly with the compound. Disruption of the TgBRADIN/GRA24 gene leads to enhanced differentiation of the parasite, and the TgBRADIN/GRA24 knockout parasites show decreased susceptibility to the differentiation-enhancing effects of Compound 2. This study represents the first use of yeast three-hybrid analysis to study small-molecule mechanism of action in any pathogenic microorganism, and it identifies a previously unrecognized inhibitor of differentiation in T. gondii. A better understanding of the proteins and mechanisms regulating T. gondii differentiation will enable new approaches to preventing the establishment of chronic infection in this important human pathogen.
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Affiliation(s)
- Anahi V Odell
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, United States of America
| | - Fanny Tran
- School of Chemistry and Biomedical Sciences Research Complex, University of St. Andrews and EaStCHEM, St Andrews, Fife, Scotland, United Kingdom
| | - Jenna E Foderaro
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, United States of America
| | - Séverine Poupart
- School of Chemistry and Biomedical Sciences Research Complex, University of St. Andrews and EaStCHEM, St Andrews, Fife, Scotland, United Kingdom
| | - Ravi Pathak
- School of Chemistry and Biomedical Sciences Research Complex, University of St. Andrews and EaStCHEM, St Andrews, Fife, Scotland, United Kingdom
| | - Nicholas J Westwood
- School of Chemistry and Biomedical Sciences Research Complex, University of St. Andrews and EaStCHEM, St Andrews, Fife, Scotland, United Kingdom
| | - Gary E Ward
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, United States of America
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Bussière FI, Brossier F, Le Vern Y, Niepceron A, Silvestre A, de Sablet T, Lacroix-Lamandé S, Laurent F. Reduced parasite motility and micronemal protein secretion by a p38 MAPK inhibitor leads to a severe impairment of cell invasion by the apicomplexan parasite Eimeria tenella. PLoS One 2015; 10:e0116509. [PMID: 25689363 PMCID: PMC4331428 DOI: 10.1371/journal.pone.0116509] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Accepted: 12/10/2014] [Indexed: 01/28/2023] Open
Abstract
E. tenella infection is associated with a severe intestinal disease leading to high economic losses in poultry industry. Mitogen activated protein kinases (MAPKs) are implicated in early response to infection and are divided in three pathways: p38, extracellular signal-regulated protein kinase (ERK) and c-Jun N-terminal kinase (JNK). Our objective was to determine the importance of these kinases on cell invasion by E. tenella. We evaluated the effect of specific inhibitors (ERK: PD98059, JNKII: SP600125, p38 MAPK: SB203580) on the invasion of epithelial cells. Incubation of SP600125 and SB203580 with epithelial cells and parasites significantly inhibited cell invasion with the highest degree of inhibition (90%) for SB203580. Silencing of the host p38α MAPK expression by siRNA led to only 20% decrease in cell invasion. In addition, when mammalian epithelial cells were pre-treated with SB203580, and washed prior infection, a 30% decrease in cell invasion was observed. This decrease was overcome when a p38 MAPK activator, anisomycin was added during infection. This suggests an active but limited role of the host p38 MAPK in this process. We next determined whether SB203580 has a direct effect on the parasite. Indeed, parasite motility and secretion of micronemal proteins (EtMIC1, 2, 3 and 5) that are involved in cell invasion were both decreased in the presence of the inhibitor. After chasing the inhibitor, parasite motility and secretion of micronemal proteins were restored and subsequently cell invasion. SB203580 inhibits cell invasion by acting partly on the host cell and mainly on the parasite.
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Affiliation(s)
- Françoise I. Bussière
- Apicomplexes et Immunité Mucosale, INRA, UMR1282, Infectiologie et Santé Publique, F-37380 Nouzilly, France
- Université François Rabelais de Tours, UMR1282, Infectiologie et Santé Publique, F-37000 Tours, France
- * E-mail:
| | - Fabien Brossier
- Apicomplexes et Immunité Mucosale, INRA, UMR1282, Infectiologie et Santé Publique, F-37380 Nouzilly, France
- Université François Rabelais de Tours, UMR1282, Infectiologie et Santé Publique, F-37000 Tours, France
| | - Yves Le Vern
- Université François Rabelais de Tours, UMR1282, Infectiologie et Santé Publique, F-37000 Tours, France
- Plate-forme d’Analyse Intégrative des Biomolécules, Laboratoire de Cytométrie et Fluorimétrie, INRA, UMR1282, Infectiologie et Santé Publique, F-37380 Nouzilly, France
| | - Alisson Niepceron
- Apicomplexes et Immunité Mucosale, INRA, UMR1282, Infectiologie et Santé Publique, F-37380 Nouzilly, France
- Université François Rabelais de Tours, UMR1282, Infectiologie et Santé Publique, F-37000 Tours, France
| | - Anne Silvestre
- Apicomplexes et Immunité Mucosale, INRA, UMR1282, Infectiologie et Santé Publique, F-37380 Nouzilly, France
- Université François Rabelais de Tours, UMR1282, Infectiologie et Santé Publique, F-37000 Tours, France
| | - Thibaut de Sablet
- Apicomplexes et Immunité Mucosale, INRA, UMR1282, Infectiologie et Santé Publique, F-37380 Nouzilly, France
- Université François Rabelais de Tours, UMR1282, Infectiologie et Santé Publique, F-37000 Tours, France
| | - Sonia Lacroix-Lamandé
- Apicomplexes et Immunité Mucosale, INRA, UMR1282, Infectiologie et Santé Publique, F-37380 Nouzilly, France
- Université François Rabelais de Tours, UMR1282, Infectiologie et Santé Publique, F-37000 Tours, France
| | - Fabrice Laurent
- Apicomplexes et Immunité Mucosale, INRA, UMR1282, Infectiologie et Santé Publique, F-37380 Nouzilly, France
- Université François Rabelais de Tours, UMR1282, Infectiologie et Santé Publique, F-37000 Tours, France
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46
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Yan X, Liu X, Ji Y, Tao G, Suo X. Ethanol and isopropanol trigger rapid egress of intracellular Eimeria tenella sporozoites. Parasitol Res 2014; 114:625-30. [PMID: 25407127 DOI: 10.1007/s00436-014-4224-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 11/06/2014] [Indexed: 10/24/2022]
Abstract
Egress from host cells is a vital step of the intracellular life cycle of apicomplexan parasites such as Toxoplasma gondii. This phenomenon has attracted attentions from many research groups. Previous studies have shown that ethanol could stimulate the release of microneme proteins by elevating intracellular Ca(2+) concentration of T. gondii, resulting in the parasite egress from host cells. However, little information about egress is known on Eimeria species, the causative agent of coccidiosis in poultry and livestock. In this report, we studied the effect of ethanol and isopropanol on the egress of eimerian parasites. Eimeria tenella sporozoites cultured in primary chicken kidney cells were treated with ethanol and isopropanol, then the egressed parasites were analyzed. Ethanol and isopropanol could induce the rapid egress of E. tenella sporozoites from host cells. No substantial damage was found in parasite-egressed host cells. Compared to the freshly isolated sporozoites, the re-invading ability and reproductivity of the egressed parasites significantly decreased by 43.4 and 44.1 % individually. We also found that fewer sporozoites egressed from host cells when the parasites developed for a longer time before the alcohol treatment. These results demonstrate an in vitro egress mode different from that of T. gondii, facilitating the deciphering of the mechanisms of egress of eimerian parasites.
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Affiliation(s)
- Xinlei Yan
- State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, 100193, China
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47
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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: 77] [Impact Index Per Article: 7.7] [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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48
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Tao Q, Xiao J, Wang Y, Fang K, Li N, Hu M, Zhou Y, Zhao J. Identification of genes expressed during Toxoplasma gondii infection by in vivo-induced antigen technology (IVIAT) with positive porcine sera. J Parasitol 2014; 100:470-9. [PMID: 24646180 DOI: 10.1645/13-240.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Infection of pigs with Toxoplasma gondii is a common source of human toxoplasmosis and causes serious economic losses. In vivo-induced antigen technology (IVIAT) is an effective immunological technique to identify the antigens that a pathogen specifically expressed during infection. To discover the genes that are important in T. gondii infection of pigs, we employed IVIAT using sera from infected pigs. Fourteen antigens were identified including microneme protein 11 (MIC11), dense granule protein 5 (GRA5), 18 kDa cyclophilin (C-18), serine proteinase inhibitor (PI), calmodulin (CaM), leucine-rich repeat protein ( LRRP), D-3-phosphoglycerate dehydrogenase (D3PD), elongation factor 1-gamma (EF1), and 6 hypothetical proteins. The increased transcription levels of 5 (MIC11, GRA5, C-18, PI, and CaM) of the 14 molecules identified by IVIAT were confirmed by real-time PCR. The full length or partial proteins encoded by these 5 genes were expressed in Escherichia coli , and their immunogenicity was confirmed by Western blot analysis with positive porcine sera. Further functional studies were conducted with CaM. Suppression of CaM expression by RNA interference decreased T. gondii tachyzoites cell attachment, invasion, and egress but did not influence their replication. The proteins identified in this study are predicted to be involved in cell invasion, ion-protein binding, protein folding, biosynthesis, and metabolism. The results of the functional analysis support the hypothesis that CaM contributes to parasite pathogenesis during infection. These results may have significant implications for the discovery of candidate molecules for the development of potential therapies and preventive measures against toxoplasmosis in pigs.
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Affiliation(s)
- Qing Tao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, P. R. China
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49
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Brochet M, Collins MO, Smith TK, Thompson E, Sebastian S, Volkmann K, Schwach F, Chappell L, Gomes AR, Berriman M, Rayner JC, Baker DA, Choudhary J, Billker O. Phosphoinositide metabolism links cGMP-dependent protein kinase G to essential Ca²⁺ signals at key decision points in the life cycle of malaria parasites. PLoS Biol 2014; 12:e1001806. [PMID: 24594931 PMCID: PMC3942320 DOI: 10.1371/journal.pbio.1001806] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 01/23/2014] [Indexed: 12/04/2022] Open
Abstract
Many critical events in the Plasmodium life cycle rely on the controlled release of Ca²⁺ from intracellular stores to activate stage-specific Ca²⁺-dependent protein kinases. Using the motility of Plasmodium berghei ookinetes as a signalling paradigm, we show that the cyclic guanosine monophosphate (cGMP)-dependent protein kinase, PKG, maintains the elevated level of cytosolic Ca²⁺ required for gliding motility. We find that the same PKG-dependent pathway operates upstream of the Ca²⁺ signals that mediate activation of P. berghei gametocytes in the mosquito and egress of Plasmodium falciparum merozoites from infected human erythrocytes. Perturbations of PKG signalling in gliding ookinetes have a marked impact on the phosphoproteome, with a significant enrichment of in vivo regulated sites in multiple pathways including vesicular trafficking and phosphoinositide metabolism. A global analysis of cellular phospholipids demonstrates that in gliding ookinetes PKG controls phosphoinositide biosynthesis, possibly through the subcellular localisation or activity of lipid kinases. Similarly, phosphoinositide metabolism links PKG to egress of P. falciparum merozoites, where inhibition of PKG blocks hydrolysis of phosphatidylinostitol (4,5)-bisphosphate. In the face of an increasing complexity of signalling through multiple Ca²⁺ effectors, PKG emerges as a unifying factor to control multiple cellular Ca²⁺ signals essential for malaria parasite development and transmission.
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Affiliation(s)
- Mathieu Brochet
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Mark O. Collins
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Terry K. Smith
- Schools of Biology and Chemistry, Biomedical Sciences Research Complex, The North Haugh, The University of Saint Andrews, St. Andrews, Fife United Kingdom
| | - Eloise Thompson
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Sarah Sebastian
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Katrin Volkmann
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Frank Schwach
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Lia Chappell
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Ana Rita Gomes
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Matthew Berriman
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Julian C. Rayner
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - David A. Baker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Jyoti Choudhary
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Oliver Billker
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
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50
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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: 161] [Impact Index Per Article: 16.1] [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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