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High-Throughput Screening to Identify Inhibitors of Plasmodium falciparum Importin α. Cells 2022; 11:cells11071201. [PMID: 35406765 PMCID: PMC8997399 DOI: 10.3390/cells11071201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 03/25/2022] [Accepted: 03/29/2022] [Indexed: 11/16/2022] Open
Abstract
The global burden of malaria and toxoplasmosis has been limited by the use of efficacious anti-parasitic agents, however, emerging resistance in Plasmodium species and Toxoplasma gondii threatens disease control worldwide, implying that new agents/therapeutic targets are urgently needed. Nuclear localization signal (NLS)-dependent transport into the nucleus, mediated by members of the importin (IMP) superfamily of nuclear transporters, has shown potential as a target for intervention to limit viral infection. Here, we show for the first time that IMPα from P. falciparum and T. gondii have promise as targets for small molecule inhibitors. We use high-throughput screening to identify agents able to inhibit P. falciparum IMPα binding to a P. falciparum NLS, identifying a number of compounds that inhibit binding in the µM-nM range, through direct binding to P. falciparum IMPα, as shown in thermostability assays. Of these, BAY 11-7085 is shown to be a specific inhibitor of P. falciparum IMPα-NLS recognition. Importantly, a number of the inhibitors limited growth by both P. falciparum and T. gondii. The results strengthen the hypothesis that apicomplexan IMPα proteins have potential as therapeutic targets to aid in identifying novel agents for two important, yet neglected, parasitic diseases.
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2
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Tedla MG, Every AL, Scheerlinck JPY. Investigating immune responses to parasites using transgenesis. Parasit Vectors 2019; 12:303. [PMID: 31202271 PMCID: PMC6570953 DOI: 10.1186/s13071-019-3550-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 06/03/2019] [Indexed: 11/10/2022] Open
Abstract
Parasites comprise diverse and complex organisms, which substantially impact human and animal health. Most parasites have complex life-cycles, and by virtue of co-evolution have developed multifaceted, often life-cycle stage-specific relationships with the immune system of their hosts. The complexity in the biology of many parasites often limits our knowledge of parasite-specific immune responses, to in vitro studies only. The relatively recent development of methods to stably manipulate the genetic make-up of many parasites has allowed a better understanding of host-parasite interactions, particularly in vivo. In this regard, the use of transgenic parasites can facilitate the study of immunomodulatory mechanisms under in vivo conditions. Therefore, in this review, we specifically highlighted the current developments in the use of transgenic parasites to unravel the host's immune response to different life-cycle stages of some key parasite species such as Leishmania, Schistosoma, Toxoplasma, Plasmodium and Trypanosome and to some degree, the use of transgenic nematode parasites is also briefly discussed.
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Affiliation(s)
- Mebrahtu G. Tedla
- Centre for Animal Biotechnology, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Melbourne, VIC 3010 Australia
| | - Alison L. Every
- Centre for Animal Biotechnology, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Melbourne, VIC 3010 Australia
- Present Address: College of Science, Health and Engineering, La Trobe University, Melbourne, VIC 3086 Australia
| | - Jean-Pierre Y. Scheerlinck
- Centre for Animal Biotechnology, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Melbourne, VIC 3010 Australia
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3
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Attias M, Miranda K, De Souza W. Development and fate of the residual body of Toxoplasma gondii. Exp Parasitol 2018; 196:1-11. [PMID: 30476495 DOI: 10.1016/j.exppara.2018.11.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 11/11/2018] [Accepted: 11/13/2018] [Indexed: 01/17/2023]
Abstract
As the tachyzoite form of Toxoplasma gondii divides inside the parasitophorous vacuole, the daughter cells remain attached to each other at the posterior end through the so-called residual body (RB). Here, we studied this process using field emission scanning electron microscopy of dry scraped infected cells, transmission electron microscopy of random ultrathin sections, X-ray microanalysis, and 3-D modelling of tomographic volumes and slice and view series obtained by FIB SEM at 7, 24, and 48 h post infection. Combining these methods of observation, we traced a timeline of events for the formation, development, and fate of the RB. The RB is formed as the first endodyogenic division is complete. Before that, finger-like invaginations at the posterior end of the tachyzoite secrete tubules from the intravacuolar network. The RB is roughly spherical and measures 1 μm in diameter at random. Its size does not vary considerably as the division cycles that form the rosette proceed. The contents of the RB are similar to the cytoplasm of the parasites. It contains ER membranous profiles and vacuolar structures identified as acidocalcisomes. This was confirmed by microanalysis. Mitochondrial profiles seen inside the RB are actually branches of mother cell mitochondrion not yet split between the two daughter cells. Acidocalcisomes of a mother cell are distributed between the two daughter cells, but as the rosette of parasites grow, acidocalcisomes seem to concentrate inside the RB where they are usually larger and tend to fuse to each other, filling most of the space in the RB. Here we hypothesize that, upon egress, the acidocalcisomes would ultimately fuse with the RB membrane liberating its contents inside the parasitophorous vacuole (PV) and, by doing so; the RB would disintegrate, releasing its contents in the PV.
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Affiliation(s)
- Marcia Attias
- Universidade Federal do Rio de Janeiro, Instituto de Biofísica Carlos Chagas Filho, Brazil.
| | - Kildare Miranda
- Instituto de Biofísica Carlos Chagas Filho, Biologia Celular, Laboratório de Ultraestrutura Celular Hertha Meyer, Brazil
| | - Wanderley De Souza
- Instituto de Biofísica Carlos Chagas Filho, Biologia Celular, Laboratório de Ultraestrutura Celular Hertha Meyer, Brazil
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4
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Gorla SK, Kavitha M, Zhang M, Chin JEW, Liu X, Striepen B, Makowska-Grzyska M, Kim Y, Joachimiak A, Hedstrom L, Cuny GD. Optimization of benzoxazole-based inhibitors of Cryptosporidium parvum inosine 5'-monophosphate dehydrogenase. J Med Chem 2013; 56:4028-43. [PMID: 23668331 DOI: 10.1021/jm400241j] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cryptosporidium parvum is an enteric protozoan parasite that has emerged as a major cause of diarrhea, malnutrition, and gastroenteritis and poses a potential bioterrorism threat. C. parvum synthesizes guanine nucleotides from host adenosine in a streamlined pathway that relies on inosine 5'-monophosphate dehydrogenase (IMPDH). We have previously identified several parasite-selective C. parvum IMPDH (CpIMPDH) inhibitors by high-throughput screening. In this paper, we report the structure-activity relationship (SAR) for a series of benzoxazole derivatives with many compounds demonstrating CpIMPDH IC50 values in the nanomolar range and >500-fold selectivity over human IMPDH (hIMPDH). Unlike previously reported CpIMPDH inhibitors, these compounds are competitive inhibitors versus NAD(+). The SAR study reveals that pyridine and other small heteroaromatic substituents are required at the 2-position of the benzoxazole for potent inhibitory activity. In addition, several other SAR conclusions are highlighted with regard to the benzoxazole and the amide portion of the inhibitor, including preferred stereochemistry. An X-ray crystal structure of a representative E·IMP·inhibitor complex is also presented. Overall, the secondary amine derivative 15a demonstrated excellent CpIMPDH inhibitory activity (IC50 = 0.5 ± 0.1 nM) and moderate stability (t1/2 = 44 min) in mouse liver microsomes. Compound 73, the racemic version of 15a, also displayed superb antiparasitic activity in a Toxoplasma gondii strain that relies on CpIMPDH (EC50 = 20 ± 20 nM), and selectivity versus a wild-type T. gondii strain (200-fold). No toxicity was observed (LD50 > 50 μM) against a panel of four mammalian cells lines.
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Affiliation(s)
- Suresh Kumar Gorla
- Department of Biology, Brandeis University , 415 South Street, Waltham, Massachusetts 02454, USA
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5
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Plasmodium falciparum metabolic pathways (MPMP) project upgraded with a database of subcellular locations of gene products. Trends Parasitol 2011; 27:285-6. [PMID: 21493145 DOI: 10.1016/j.pt.2011.03.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 03/13/2011] [Accepted: 03/14/2011] [Indexed: 11/23/2022]
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6
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John B, Weninger W, Hunter CA. Advances in imaging the innate and adaptive immune response to Toxoplasma gondii. Future Microbiol 2011; 5:1321-8. [PMID: 20860479 DOI: 10.2217/fmb.10.97] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Toxoplasma gondii is an intracellular protozoan parasite that infects a wide variety of warm-blooded hosts and can have devastating effects in the developing fetus as well as the immunocompromised host. An appreciation of how this organism interacts with the host immune system is crucial to understanding the pathogenesis of this disease. The last decade has been marked by the application of various imaging techniques, such as bioluminescent imaging as well as confocal and multiphoton microscopy to study toxoplasmosis. The ability to manipulate parasites to express fluorescent/bioluminescent markers or model antigens/enzymes combined with the development of reporter mice that allow the detection of distinct immune populations have been crucial to the success of many of these studies. These approaches have permitted the visualization of parasites and immune cells in real-time and provided new insights into the nature of host-pathogen interactions. This article highlights some of the advances in imaging techniques, their strengths and weaknesses, and how these techniques have impacted our understanding of the interaction between parasites and various immune populations during toxoplasmosis.
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Affiliation(s)
- Beena John
- Department of Pathobiology, University of Pennsylvania, Philadelphia, 19104, USA
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7
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Leishmania (Viannia) panamensis: an in vitro assay using the expression of GFP for screening of antileishmanial drug. Exp Parasitol 2009; 122:134-9. [PMID: 19303871 DOI: 10.1016/j.exppara.2009.02.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 11/28/2008] [Accepted: 02/06/2009] [Indexed: 11/23/2022]
Abstract
Promastigotes of Leishmania (Viannia) panamensis were successfully transfected with p6.5-egfp to express green fluorescent protein. The transfectants remained infective to macrophages, providing an in vitro model for screening antileishmanial drugs. This was demonstrated by flow cytometry of macrophage-associated GFP after exposure of infected cultures to known antileishmanial drugs, i.e. amphotericin B and glucantime. Fluorescence of GFP diminished progressively from infected cells with increasing drug concentrations used in both cases. The availability of this fluorescent assay for infection of macrophages by L. (V.) panamensis facilitates drug discovery program for the Viannia species, which differ significantly from those of the Leishmania subgenus.
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8
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Ferguson DJP. Toxoplasma gondii: 1908-2008, homage to Nicolle, Manceaux and Splendore. Mem Inst Oswaldo Cruz 2009; 104:133-48. [DOI: 10.1590/s0074-02762009000200003] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Accepted: 10/20/2008] [Indexed: 01/19/2023] Open
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9
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Meissner M, Klaus K. What new cell biology findings could bring to therapeutics: is it time for a phenome-project in Toxoplasma gondii? Mem Inst Oswaldo Cruz 2009; 104:185-9. [DOI: 10.1590/s0074-02762009000200010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Accepted: 12/03/2008] [Indexed: 12/27/2022] Open
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10
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Dzierszinski FS, Hunter CA. Advances in the use of genetically engineered parasites to study immunity to Toxoplasma gondii. Parasite Immunol 2008; 30:235-44. [PMID: 18194347 DOI: 10.1111/j.1365-3024.2007.01016.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Studying in vivo biology and the host immune response to Toxoplasma gondii has yielded many insights into the pathogenesis of this parasitic organism. It is recognized that this infection in immune competent hosts elicits a strong Th1-type response, which is characterized by the generation of parasite-specific CD4(+) and CD8(+) T cells that produce IFN-gamma and provide protective immunity. One of the problems associated with studying resistance to Toxoplasma has been the lack of reagents to track parasite-specific T cell responses with a high degree of specificity. To overcome this difficulty, it is possible to use a combination of transgenic parasites that are engineered to express well-characterized heterologous reporters or antigens, and T cell hybridomas or naïve T cells that express a T cell receptor specific for the processed peptide. These approaches have provided new insights into parasite dissemination, antigen presentation, as well as immune regulation.
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Affiliation(s)
- F S Dzierszinski
- Institute of Parasitology, McGill University, Ste-Anne-de-Bellevue, Canada.
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11
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Tilley L, McFadden G, Cowman A, Klonis N. Illuminating Plasmodium falciparum-infected red blood cells. Trends Parasitol 2007; 23:268-77. [PMID: 17434344 DOI: 10.1016/j.pt.2007.04.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 03/21/2007] [Accepted: 04/04/2007] [Indexed: 11/20/2022]
Abstract
The malaria parasite undergoes a remarkable series of morphological transformations, which underpin its life in both human and mosquito hosts. The advent of molecular transfection technology coupled with the ability to introduce fluorescent reporter proteins that faithfully track and expose the activities of parasite proteins has revolutionized our view of parasite cell biology. The greatest insights have been realized in the erythrocyte stages of Plasmodium falciparum. P. falciparum invades and remodels the human erythrocyte: it feeds on haemoglobin, grows and divides, and subverts the physiology of its hapless host. Fluorescent proteins have been employed to track and dissect each of these processes and have revealed details and exposed new paradigms.
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Affiliation(s)
- Leann Tilley
- Department of Biochemistry, La Trobe University, Melbourne, Victoria 3086, Australia.
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12
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Fleige T, Fischer K, Ferguson DJP, Gross U, Bohne W. Carbohydrate metabolism in the Toxoplasma gondii apicoplast: localization of three glycolytic isoenzymes, the single pyruvate dehydrogenase complex, and a plastid phosphate translocator. EUKARYOTIC CELL 2007; 6:984-96. [PMID: 17449654 PMCID: PMC1951530 DOI: 10.1128/ec.00061-07] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Many apicomplexan parasites, such as Toxoplasma gondii and Plasmodium species, possess a nonphotosynthetic plastid, referred to as the apicoplast, which is essential for the parasites' viability and displays characteristics similar to those of nongreen plastids in plants. In this study, we localized several key enzymes of the carbohydrate metabolism of T. gondii to either the apicoplast or the cytosol by engineering parasites which express epitope-tagged fusion proteins. The cytosol contains a complete set of enzymes for glycolysis, which should enable the parasite to metabolize imported glucose into pyruvate. All the glycolytic enzymes, from phosphofructokinase up to pyruvate kinase, are present in the T. gondii genome, as duplicates and isoforms of triose phosphate isomerase, phosphoglycerate kinase, and pyruvate kinase were found to localize to the apicoplast. The mRNA expression levels of all genes with glycolytic products were compared between tachyzoites and bradyzoites; however, a strict bradyzoite-specific expression pattern was observed only for enolase I. The T. gondii genome encodes a single pyruvate dehydrogenase complex, which was located in the apicoplast and absent in the mitochondrion, as shown by targeting of epitope-tagged fusion proteins and by immunolocalization of the native pyruvate dehydrogenase complex. The exchange of metabolites between the cytosol and the apicoplast is likely to be mediated by a phosphate translocator which was localized to the apicoplast. Based on these localization studies, a model is proposed that explains the supply of the apicoplast with ATP and the reduction power, as well as the exchange of metabolites between the cytosol and the apicoplast.
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Affiliation(s)
- Tobias Fleige
- Institute of Medical Microbiology, University of Göttingen, Kreuzbergring 57, D-37075 Göttingen, Germany
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13
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Meissner M, Agop-Nersesian C, Sullivan WJ. Molecular tools for analysis of gene function in parasitic microorganisms. Appl Microbiol Biotechnol 2007; 75:963-75. [PMID: 17401559 DOI: 10.1007/s00253-007-0946-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 03/12/2007] [Accepted: 03/12/2007] [Indexed: 01/01/2023]
Abstract
With the completion of several genome sequences for parasitic protozoa, research in molecular parasitology entered the "post-genomic" era. Accompanied by global transcriptome and proteome analysis, huge datasets have been generated that have added many novel candidates to the list of drug and vaccine targets. The challenge is now to validate these factors and to bring science back to the bench to perform a detailed characterization. In some parasites, like Trypanosoma brucei, high-throughput genetic screens have been established using RNA interference [for a detailed review, see Motyka and Englund (2004)]. In most protozoan parasites, however, more time-consuming approaches have to be employed to identify and characterize the function of promising candidates in detail. This review aims to summarize the status of molecular genetic tools available for a variety of protozoan pathogens and discuss how they can be implemented to advance our understanding of parasite biology.
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Affiliation(s)
- Markus Meissner
- Hygieneinstitut, Abteilung Parasitologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany.
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14
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Sanchez BAM, Varotti FP, Rodrigues FG, Carvalho LH. Validation of a Plasmodium falciparum parasite transformed with green fluorescent protein for antimalarial drug screening. J Microbiol Methods 2007; 69:518-22. [PMID: 17466399 DOI: 10.1016/j.mimet.2007.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2006] [Revised: 03/07/2007] [Accepted: 03/07/2007] [Indexed: 11/27/2022]
Abstract
Aiming to replace the radioisotopic assay, the widely used procedure for vitro antimalarial drug screening, we set up a protocol using a Plasmodium falciparum strain transformed with the green fluorescent protein (PfGFP), which can be quickly and specifically quantified by flow cytometry. On the basis of a side-by-side comparison, this PfGFP-based method showed results similar to those obtained with the standard radioisotopic method.
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Affiliation(s)
- Bruno A M Sanchez
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Av. Augusto de Lima 1715, 30190-002 Belo Horizonte, Minas Gerais, Brazil
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15
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Gubbels MJ, Wieffer M, Striepen B. Fluorescent protein tagging in Toxoplasma gondii: identification of a novel inner membrane complex component conserved among Apicomplexa. Mol Biochem Parasitol 2005; 137:99-110. [PMID: 15279956 DOI: 10.1016/j.molbiopara.2004.05.007] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2004] [Revised: 05/05/2004] [Accepted: 05/06/2004] [Indexed: 10/26/2022]
Abstract
Toxoplasma gondii is an obligate intracellular parasite, and its sub-cellular organization shows clear adaptations to this life-style. In addition to organelles shared among all eukaryotes, the organism possesses a number of specialized compartments with important roles in host cell invasion and intra-cellular survival. These unique aspects of the parasite's biology are also reflected in its genome. The ongoing genome sequencing efforts for T. gondii and related apicomplexans predict a high proportion of genes unique to the phylum, which lack homologs in other model organisms. Knowing the sub-cellular localization of these gene products will be an important first step towards their functional characterization. We used a library approach wherein parasite genomic DNA was fused to the yellow fluorescent protein (YFP) gene. Parasites transformed with this library were screened by flow cytometry and fluorescence microscopy. Clones tagged in a wide variety of sub-cellular compartments (nucleus, mitochondria, ER, dense granules (secreted), spliceosome, plasma membrane, apicoplast, inner membrane complex) were isolated and confirmed using compartment specific markers. Clones with tags in parasite-specific localizations were subjected to insert rescue and phenotypic verification using an in vitro recombination system. Among the genes identified is a novel inner membrane complex gene (IMC3) conserved among Apicomplexa.
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Affiliation(s)
- Marc-Jan Gubbels
- Center for Tropical and Emerging Global Diseases, University of Georgia, 724 Biological Sciences Building, Athens 30602, USA
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Hall VJ, Ruddock NT, French AJ. Expression profiling of genes crucial for placental and preimplantation development in bovine in vivo, in vitro, and nuclear transfer blastocysts. Mol Reprod Dev 2005; 72:16-24. [PMID: 15898073 DOI: 10.1002/mrd.20337] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Placental abnormalities and failed implantation are characterized phenotypes that occur in many species as a result of somatic cell cloning. This study examines a number of genes, critical for early placental development and reports aberrant expression patterns in a number of cloned bovine blastocysts, thus implicating a role of these genes in failed implantation. Messenger RNA (mRNA) expression of eight genes critical for early placental and preimplantation development including Acrogranin, Cdx2, Eomes, ErbB3, ERR2, Hand1, MRJ, and Rex1 were analyzed in single, in vivo, in vitro, and cloned bovine blastocysts (produced by hand-made cloning (HMC) and serial hand-made cloning (SHMC)) following complementary DNA (cDNA) amplification with a SMART cDNA synthesis kit. Aberrant expression of Acrogranin, Cdx2, and ERR2 was detected in a number of blastocysts produced by SHMC. Other genes, Eomes and Hand1, were not detectable in, in vivo bovine blastocysts, suggesting a differential expression pattern between bovine and murine embryos. A number of control marker genes including Oct4, IFN-tau, and PolyA were expressed in all single blastocysts analyzed. This is the first study to report that failure of implantation may be due to aberrant expression of genes in the preimplantation cloned embryo, which are crucial for the early regulation and differentiation of the placenta.
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Affiliation(s)
- Vanessa J Hall
- Centre for Early Human Development, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia
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