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Etheridge RD. Protozoan phagotrophy from predators to parasites: An overview of the enigmatic cytostome-cytopharynx complex of Trypanosoma cruzi. J Eukaryot Microbiol 2022; 69:e12896. [PMID: 35175673 PMCID: PMC11110969 DOI: 10.1111/jeu.12896] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 02/14/2022] [Accepted: 02/14/2022] [Indexed: 11/28/2022]
Abstract
Eating is fundamental and from this basic principle, living organisms have evolved innumerable strategies to capture energy and nutrients from their environment. As part of the world's aquatic ecosystems, the expansive family of heterotrophic protozoans uses self-generated currents to funnel prokaryotic prey into an ancient, yet highly enigmatic, oral apparatus known as the cytostome-cytopharynx complex prior to digestion. Despite its near ubiquitous presence in protozoans, little is known mechanistically about how this feeding organelle functions. Intriguingly, one class of these flagellated phagotrophic predators known as the kinetoplastids gave rise to a lineage of obligate parasitic protozoa, the trypanosomatids, that can infect a wide variety of organisms ranging from plants to humans. One parasitic species of humans, Trypanosoma cruzi, has retained this ancestral organelle much like its free-living relatives and continues to use it as its primary mode of endocytosis. In this review, we will highlight foundational observations made regarding the cytostome-cytopharynx complex and examine some of the most pressing questions regarding the mechanistic basis for its function. We propose that T. cruzi has the potential to serve as an excellent model system to dissect the enigmatic process of protozoal phagotrophy and thus enhance our overall understanding of fundamental eukaryotic biology.
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Affiliation(s)
- Ronald Drew Etheridge
- Department of Cellular Biology, Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, Georgia, USA
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2
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Rico E, Jeacock L, Kovářová J, Horn D. Inducible high-efficiency CRISPR-Cas9-targeted gene editing and precision base editing in African trypanosomes. Sci Rep 2018; 8:7960. [PMID: 29785042 PMCID: PMC5962531 DOI: 10.1038/s41598-018-26303-w] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 05/09/2018] [Indexed: 12/21/2022] Open
Abstract
The Cas9 endonuclease can be programmed by guide RNA to introduce sequence-specific breaks in genomic DNA. Thus, Cas9-based approaches present a range of novel options for genome manipulation and precision editing. African trypanosomes are parasites that cause lethal human and animal diseases. They also serve as models for studies on eukaryotic biology, including 'divergent' biology. Genome modification, exploiting the native homologous recombination machinery, has been important for studies on trypanosomes but often requires multiple rounds of transfection using selectable markers that integrate at low efficiency. We report a system for delivering tetracycline inducible Cas9 and guide RNA to Trypanosoma brucei. In these cells, targeted DNA cleavage and gene disruption can be achieved at close to 100% efficiency without further selection. Disruption of aquaglyceroporin (AQP2) or amino acid transporter genes confers resistance to the clinical drugs pentamidine or eflornithine, respectively, providing simple and robust assays for editing efficiency. We also use the new system for homology-directed, precision base editing; a single-stranded oligodeoxyribonucleotide repair template was delivered to introduce a single AQP2 - T791G/L264R mutation in this case. The technology we describe now enables a range of novel programmed genome-editing approaches in T. brucei that would benefit from temporal control, high-efficiency and precision.
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Affiliation(s)
- Eva Rico
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK
| | - Laura Jeacock
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK
| | - Julie Kovářová
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK
| | - David Horn
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK.
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Wang JL, Huang SY, Behnke MS, Chen K, Shen B, Zhu XQ. The Past, Present, and Future of Genetic Manipulation in Toxoplasma gondii. Trends Parasitol 2016; 32:542-553. [PMID: 27184069 DOI: 10.1016/j.pt.2016.04.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 04/20/2016] [Accepted: 04/21/2016] [Indexed: 12/16/2022]
Abstract
Toxoplasma gondii is a classic model for studying obligate intracellular microorganisms as various genetic manipulation tools have been developed in T. gondii over the past 20 years. Here we summarize the major strategies for T. gondii genetic manipulation including genetic crosses, insertional mutagenesis, chemical mutagenesis, homologous gene replacement, conditional knockdown techniques, and the recently developed clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 system. We evaluate the advantages and limitations of each of these tools in a historical perspective. We also discuss additional applications of modified CRISPR-Cas9 systems for use in T. gondii, such as regulation of gene expression, labeling of specific genomic loci, and epigenetic modifications. These approaches have the potential to revolutionize the analysis of T. gondii biology and help us to better develop new drugs and vaccines.
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Affiliation(s)
- Jin-Lei Wang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, PR China
| | - Si-Yang Huang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, PR China; Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu Province 225009, PR China
| | - Michael S Behnke
- Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Kai Chen
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, PR China
| | - Bang Shen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei Province 430070, PR China.
| | - Xing-Quan Zhu
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, PR China; Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu Province 225009, PR China.
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4
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Krüger T, Engstler M. Flagellar motility in eukaryotic human parasites. Semin Cell Dev Biol 2015; 46:113-27. [DOI: 10.1016/j.semcdb.2015.10.034] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 10/26/2015] [Accepted: 10/26/2015] [Indexed: 12/31/2022]
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Lu F, Li J, Wang B, Cheng Y, Kong DH, Cui L, Ha KS, Sattabongkot J, Tsuboi T, Han ET. Profiling the humoral immune responses to Plasmodium vivax infection and identification of candidate immunogenic rhoptry-associated membrane antigen (RAMA). J Proteomics 2014; 102:66-82. [PMID: 24607491 DOI: 10.1016/j.jprot.2014.02.029] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 02/05/2014] [Accepted: 02/23/2014] [Indexed: 11/17/2022]
Abstract
UNLABELLED Completion of sequencing of the Plasmodium vivax genome and transcriptome offers the chance to identify antigens among >5000 candidate proteins. To identify those P. vivax proteins that are immunogenic, a total of 152 candidate proteins (160 fragments) were expressed using a wheat germ cell-free system. The results of Western blot analysis showed that 92.5% (148/160) of the targets were expressed, and 96.6% (143/148) were in a soluble form with 67.7% of solubility rate. The proteins were screened by protein arrays with sera from 22 vivax malaria patients and 10 healthy individuals to confirm their immune profile, and 44 (27.5%, 44/160) highly reactive P. vivax antigens were identified. Overall, 5 candidates (rhoptry-associated membrane antigen [RAMA], Pv-fam-a and -b, EXP-1 and hypothetical protein PVX_084775) showed a positive reaction with >80% of patient sera, and 21 candidates with 50% to 80%. More than 23% of the highly immunoreactive proteins were hypothetical proteins, described for the first time in this study. One of the top immunogenic proteins, RAMA, was characterized and confirmed to be a serological marker of recent exposure to P. vivax infection. These novel immunoproteomes should greatly facilitate the identification of promising novel malaria antigens and may warrant further study. BIOLOGICAL SIGNIFICANCE The establishment of high-throughput cloning and expression systems has permitted the construction of protein arrays for proteome-wide study of Plasmodium vivax. In this study, high-throughput screening assays have been applied to investigate blood stage-specific immune proteomes from P. vivax. We identified 44 antigenic proteins from the 152 putative candidates, more than 23% of which were hypothetical proteins described for the first time in this study. In addition, PvRAMA was characterized further and confirmed to be a serological marker of exposure to infections. The expression of one-third of the selected antigenic genes were shifted between P. vivax and Plasmodium falciparum, suggesting that these genes may represent important factors associated with P. vivax selectivity for young erythrocytes and/or with immune evasion. These novel immune proteomes of the P. vivax blood stage provide a baseline for further prospective serological marker studies in malaria. These methods could be used to determine immunodominant candidate antigens from the P. vivax genome.
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Affiliation(s)
- Feng Lu
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea; Jiangsu Institute of Parasitic Diseases, Key Laboratory on Technology for Parasitic Disease Prevention and Control, Ministry of Health, Wuxi, Jiangsu, People's Republic of China
| | - Jian Li
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea; Jiangsu Institute of Parasitic Diseases, Key Laboratory on Technology for Parasitic Disease Prevention and Control, Ministry of Health, Wuxi, Jiangsu, People's Republic of China
| | - Bo Wang
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea
| | - Yang Cheng
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea
| | - Deok-Hoon Kong
- Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea
| | - Liwang Cui
- Department of Entomology, The Pennsylvania State University, University Park, PA, USA
| | - Kwon-Soo Ha
- Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan.
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chunchon, Gangwon-do, Republic of Korea.
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Sanz S, Bandini G, Ospina D, Bernabeu M, Mariño K, Fernández-Becerra C, Izquierdo L. Biosynthesis of GDP-fucose and other sugar nucleotides in the blood stages of Plasmodium falciparum. J Biol Chem 2013; 288:16506-16517. [PMID: 23615908 DOI: 10.1074/jbc.m112.439828] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Carbohydrate structures play important roles in many biological processes, including cell adhesion, cell-cell communication, and host-pathogen interactions. Sugar nucleotides are activated forms of sugars used by the cell as donors for most glycosylation reactions. Using a liquid chromatography-tandem mass spectrometry-based method, we identified and quantified the pools of UDP-glucose, UDP-galactose, UDP-N-acetylglucosamine, GDP-mannose, and GDP-fucose in Plasmodium falciparum intraerythrocytic life stages. We assembled these data with the in silico functional reconstruction of the parasite metabolic pathways obtained from the P. falciparum annotated genome, exposing new active biosynthetic routes crucial for further glycosylation reactions. Fucose is a sugar present in glycoconjugates often associated with recognition and adhesion events. Thus, the GDP-fucose precursor is essential in a wide variety of organisms. P. falciparum presents homologues of GDP-mannose 4,6-dehydratase and GDP-L-fucose synthase enzymes that are active in vitro, indicating that most GDP-fucose is formed by a de novo pathway that involves the bioconversion of GDP-mannose. Homologues for enzymes involved in a fucose salvage pathway are apparently absent in the P. falciparum genome. This is in agreement with in vivo metabolic labeling experiments showing that fucose is not significantly incorporated by the parasite. Fluorescence microscopy of epitope-tagged versions of P. falciparum GDP-mannose 4,6-dehydratase and GDP-L-fucose synthase expressed in transgenic 3D7 parasites shows that these enzymes localize in the cytoplasm of P. falciparum during the intraerythrocytic developmental cycle. Although the function of fucose in the parasite is not known, the presence of GDP-fucose suggests that the metabolite may be used for further fucosylation reactions.
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Affiliation(s)
- Sílvia Sanz
- Barcelona Centre for International Health Research, Hospital Clínic-Universitat de Barcelona, CEK, 1a Planta, Rosselló 149-153, 08036, Barcelona, Spain
| | - Giulia Bandini
- College of Life Sciences, University of Dundee, Division of Biological Chemistry and Drug Discovery, Wellcome Trust Biocentre, Dundee DD15EH, Scotland, United Kingdom
| | - Diego Ospina
- Barcelona Centre for International Health Research, Hospital Clínic-Universitat de Barcelona, CEK, 1a Planta, Rosselló 149-153, 08036, Barcelona, Spain
| | - Maria Bernabeu
- Barcelona Centre for International Health Research, Hospital Clínic-Universitat de Barcelona, CEK, 1a Planta, Rosselló 149-153, 08036, Barcelona, Spain
| | - Karina Mariño
- College of Life Sciences, University of Dundee, Division of Biological Chemistry and Drug Discovery, Wellcome Trust Biocentre, Dundee DD15EH, Scotland, United Kingdom
| | - Carmen Fernández-Becerra
- Barcelona Centre for International Health Research, Hospital Clínic-Universitat de Barcelona, CEK, 1a Planta, Rosselló 149-153, 08036, Barcelona, Spain
| | - Luis Izquierdo
- Barcelona Centre for International Health Research, Hospital Clínic-Universitat de Barcelona, CEK, 1a Planta, Rosselló 149-153, 08036, Barcelona, Spain.
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7
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Sullivan WJ, Jeffers V. Mechanisms of Toxoplasma gondii persistence and latency. FEMS Microbiol Rev 2012; 36:717-33. [PMID: 22091606 PMCID: PMC3319474 DOI: 10.1111/j.1574-6976.2011.00305.x] [Citation(s) in RCA: 169] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 08/22/2011] [Accepted: 08/25/2011] [Indexed: 11/28/2022] Open
Abstract
Toxoplasma gondii is an obligate intracellular protozoan parasite that causes opportunistic disease, particularly in immunocompromised individuals. Central to its transmission and pathogenesis is the ability of the proliferative stage (tachyzoite) to convert into latent tissue cysts (bradyzoites). Encystment allows Toxoplasma to persist in the host and affords the parasite a unique opportunity to spread to new hosts without proceeding through its sexual stage, which is restricted to felids. Bradyzoite tissue cysts can cause reactivated toxoplasmosis if host immunity becomes impaired. A greater understanding of the molecular mechanisms orchestrating bradyzoite development is needed to better manage the disease. Here, we will review key studies that have contributed to our knowledge about this persistent form of the parasite and how to study it, with a focus on how cellular stress can signal for the reprogramming of gene expression needed during bradyzoite development.
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Affiliation(s)
- William J Sullivan
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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Abstract
Parasitic diseases cause important losses in public and veterinary health worldwide. Novel drugs, more reliable diagnostic techniques and vaccine candidates are urgently needed. Due to the complexity of parasites and the intricate relationship with their hosts, development of successful tools to fight parasites has been very limited to date. The growing information on individual parasite genomes is now allowing the use of a broader range of potential strategies to gain deeper insights into the host-parasite relationship and has increased the possibilities to develop molecular-based tools in the field of parasitology. Nevertheless, functional studies of respective genes are still scarce. The RNA interference phenomenon resulting in the regulation of protein expression through the specific degradation of defined mRNAs, and more specifically the possibility of artificially induce it, has shown to be a powerful tool for the investigation of proteins function in many organisms. Recent advances in the design and delivery of targeting molecules allow efficient and highly specific gene silencing in different types of parasites, pointing out this technology as a powerful tool for the identification of novel vaccine candidates or drug targets at the high-throughput level in the near future, and could enable researchers to functionally annotate parasite genomes. The aim of this review is to provide a comprehensive overview on the current advances and pitfalls in gene silencing mechanisms, techniques, applications and prospects in animal parasites.
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Abstract
SUMMARYIn parasitological research, significant progress has been made with respect to genomics and transcriptomics but transgenic systems for functional gene analyses are mainly restricted to the protozoan field. Gene insertion and knockout strategies can be applied to parasitic protozoa as well as gene silencing by RNA interference (RNAi). By contrast, research on parasitic helminthes still lags behind. Along with the major advances in genome and transcriptome analyses e.g. for schistosomes, methods for the functional characterization of genes of interest are still in their initial phase and have to be elaborated now, at the beginning of the post-genomic era. In this review we will summarize attempts made in the last decade regarding the establishment of protocols to transiently and stably transform or transfect schistosomes. Besides approaches using particle bombardment, electroporation or virus-based infection strateies to introduce DNA constructs into adult and larval schistosome stages to express reporter genes, first approaches have also been made in establishing protocols based on soaking, lipofection, and/or electroporation for RNA interference to silence gene activity. Although in these cases remarkable progress can be seen, the schistosome community eagerly awaits major breakthroughs especially with respect to stable transformation, but also for silencing or knock-down strategies for every schistosome gene of interest.
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Chaturvedi AK, Lazzell AL, Saville SP, Wormley FL, Monteagudo C, Lopez-Ribot JL. Validation of the tetracycline regulatable gene expression system for the study of the pathogenesis of infectious disease. PLoS One 2011; 6:e20449. [PMID: 21633704 PMCID: PMC3102114 DOI: 10.1371/journal.pone.0020449] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 04/20/2011] [Indexed: 12/28/2022] Open
Abstract
Understanding the pathogenesis of infectious disease requires the examination and successful integration of parameters related to both microbial virulence and host responses. As a practical and powerful method to control microbial gene expression, including in vivo, the tetracycline-regulatable system has recently gained the favor of many investigative groups. However, some immunomodulatory effects of the tetracyclines, including doxycycline, could potentially limit its use to evaluate host responses during infection. Here we have used a well-established murine model of disseminated candidiasis, which is highly dependent on both the virulence displayed by the fungal cells and on the host immune status, to validate the use of this system. We demonstrate that the pathogenesis of the wild type C. albicans CAF2-1 strain, which does not contain any tet-regulatable element, is not affected by the presence of doxycycline. Moreover levels of key cytokines, chemokines and many other biomarkers, as determined by multi-analyte profiling, remain essentially unaltered by the presence of the antibiotic during infection. Our results indicate that the levels of doxycycline needed to control the tetracycline regulatable promoter gene expression system have no detectable effect on global host responses during candidiasis. Because tet-regulatable systems are now being increasingly used in a variety of pathogenic microorganisms, these observations have wide implications in the field of infectious diseases.
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Affiliation(s)
- Ashok K. Chaturvedi
- Department of Biology and South Texas Center for Emerging Infectious Diseases, University of Texas at San Antonio, Texas, United States of America
| | - Anna L. Lazzell
- Department of Biology and South Texas Center for Emerging Infectious Diseases, University of Texas at San Antonio, Texas, United States of America
| | - Stephen P. Saville
- Department of Biology and South Texas Center for Emerging Infectious Diseases, University of Texas at San Antonio, Texas, United States of America
| | - Floyd L. Wormley
- Department of Biology and South Texas Center for Emerging Infectious Diseases, University of Texas at San Antonio, Texas, United States of America
| | - Carlos Monteagudo
- Departmento de Patología, Facultad de Medicina y Odontología, Universidad de Valencia, Valencia, Spain
| | - Jose L. Lopez-Ribot
- Department of Biology and South Texas Center for Emerging Infectious Diseases, University of Texas at San Antonio, Texas, United States of America
- * E-mail:
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Limenitakis J, Soldati-Favre D. Functional genetics in Apicomplexa: potentials and limits. FEBS Lett 2011; 585:1579-88. [PMID: 21557944 DOI: 10.1016/j.febslet.2011.05.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 05/02/2011] [Accepted: 05/03/2011] [Indexed: 01/15/2023]
Abstract
The Apicomplexans are obligate intracellular protozoan parasites and the causative agents of severe diseases in humans and animals. Although complete genome sequences are available since many years and for several parasites, they are replete with putative genes of unassigned function. Forward and reverse genetic approaches are limited only to a few Apicomplexans that can either be propagated in vitro or in a convenient animal model. This review will compare and contrast the most recent strategies developed for the genetic manipulation of Plasmodium falciparum, Plasmodium berghei and Toxoplasma gondii that have taken advantage of the intrinsic features of their respective genomes. Efforts towards the improvement of the transfection efficiencies in malaria parasites, the development of approaches to study essential genes and the elaboration of high-throughput methods for the identification of gene function will be discussed.
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Affiliation(s)
- Julien Limenitakis
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva, Switzerland.
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Use of the kinase inhibitor analog 1NM-PP1 reveals a role for Toxoplasma gondii CDPK1 in the invasion step. EUKARYOTIC CELL 2010; 9:667-70. [PMID: 20173034 DOI: 10.1128/ec.00351-09] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Toxoplasma gondii CDPK1 (TgCDPK1) was found to be the target of the toxoplasmocidal compound 1NM-PP1. When TgCDPK1 was mutated at position 128 from glycine to methionine, resistance was gained. Inhibition of gliding motility without inhibition of micronemal secretion by 1NM-PP1 suggests a function for TgCDPK1 in gliding motility.
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Sullivan WJ, Smith AT, Joyce BR. Understanding mechanisms and the role of differentiation in pathogenesis of Toxoplasma gondii: a review. Mem Inst Oswaldo Cruz 2010; 104:155-61. [PMID: 19430637 DOI: 10.1590/s0074-02762009000200005] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Accepted: 12/16/2008] [Indexed: 11/22/2022] Open
Abstract
Parasite differentiation from proliferating tachyzoites into latent bradyzoites is central to pathogenesis and transmission of the intracellular protozoan pathogen Toxoplasma gondii. The presence of bradyzoite-containing cysts in human hosts and their subsequent rupture can cause life-threatening recrudescence of acute infection in the immunocompromised and cyst formation in other animals contributes to zoonotic transmission and widespread dissemination of the parasite. In this review, we discuss the evidence showing how the clinically relevant process of bradyzoite differentiation is regulated at both transcriptional and post-transcriptional levels. Specific regulatory factors implicated in modulating bradyzoite differentiation include promoter-based cis-elements, epigenetic modifications and protein translation control through eukaryotic initiation factor -2 (eIF2). In addition to a summary of the current state of knowledge in these areas we discuss the pharmacological ramifications and pose some questions for future research.
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Affiliation(s)
- William J Sullivan
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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14
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Abstract
The protozoan parasitesTrypanosoma bruceiandTrypanosoma cruziare the causative agents of African trypanosomiasis and Chagas disease, respectively. These are debilitating infections that exert a considerable health burden on some of the poorest people on the planet. Treatment of trypanosome infections is dependent on a small number of drugs that have limited efficacy and can cause severe side effects. Here, we review the properties of these drugs and describe new findings on their modes of action and the mechanisms by which resistance can arise. We further outline how a greater understanding of parasite biology is being exploited in the search for novel chemotherapeutic agents. This effort is being facilitated by new research networks that involve academic and biotechnology/pharmaceutical organisations, supported by public–private partnerships, and are bringing a new dynamism and purpose to the search for trypanocidal agents.
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15
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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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Liu X, Shi T, Ren H, Su H, Yan W, Suo X. Restriction enzyme-mediated transfection improved transfection efficiency in vitro in Apicomplexan parasite Eimeria tenella. Mol Biochem Parasitol 2008; 161:72-5. [DOI: 10.1016/j.molbiopara.2008.06.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2008] [Revised: 05/14/2008] [Accepted: 06/10/2008] [Indexed: 11/28/2022]
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Abstract
Undoubtedly, there are fundamental processes driving the structural mechanics of cell division in eukaryotic organisms that have been conserved throughout evolution and are being revealed by studies on organisms such as yeast and mammalian cells. Precision of structural mechanics of cytokinesis is however probably no better illustrated than in the protozoa. A dramatic example of this is the protozoan parasite Trypanosoma brucei, a unicellular flagellated parasite that causes a devastating disease (African sleeping sickness) across Sub-Saharan Africa in both man and animals. As trypanosomes migrate between and within a mammalian host and the tsetse vector, there are periods of cell proliferation and cell differentiation involving at least five morphologically distinct cell types. Much of the existing cytoskeleton remains intact during these processes, necessitating a very precise temporal and spatial duplication and segregation of the many single-copy organelles. This structural precision is aiding progress in understanding these processes as we apply the excellent reverse genetics and post-genomic technologies available in this system. Here we outline our current understanding of some of the structural aspects of cell division in this fascinating organism.
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18
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Greenwood BM, Fidock DA, Kyle DE, Kappe SHI, Alonso PL, Collins FH, Duffy PE. Malaria: progress, perils, and prospects for eradication. J Clin Invest 2008; 118:1266-76. [PMID: 18382739 DOI: 10.1172/jci33996] [Citation(s) in RCA: 409] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
There are still approximately 500 million cases of malaria and 1 million deaths from malaria each year. Yet recently, malaria incidence has been dramatically reduced in some parts of Africa by increasing deployment of anti-mosquito measures and new artemisinin-containing treatments, prompting renewed calls for global eradication. However, treatment and mosquito control currently depend on too few compounds and thus are vulnerable to the emergence of compound-resistant parasites and mosquitoes. As discussed in this Review, new drugs, vaccines, and insecticides, as well as improved surveillance methods, are research priorities. Insights into parasite biology, human immunity, and vector behavior will guide efforts to translate parasite and mosquito genome sequences into novel interventions.
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Affiliation(s)
- Brian M Greenwood
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
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Functional expression of ribozymes in Apicomplexa: Towards exogenous control of gene expression by inducible RNA-cleavage. Int J Parasitol 2008; 38:673-81. [DOI: 10.1016/j.ijpara.2007.10.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2007] [Revised: 10/11/2007] [Accepted: 10/12/2007] [Indexed: 11/20/2022]
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20
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Kessler H, Herm-Götz A, Hegge S, Rauch M, Soldati-Favre D, Frischknecht F, Meissner M. Microneme protein 8 – a new essential invasion factor inToxoplasma gondii. J Cell Sci 2008; 121:947-56. [PMID: 18319299 DOI: 10.1242/jcs.022350] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Apicomplexan parasites rely on sequential secretion of specialised secretory organelles for the invasion of the host cell. First, micronemes release their content upon contact with the host cell. Second, rhoptries are discharged, leading to the formation of a tight interaction (moving junction) with the host cell, through which the parasite invades. The functional characterisation of several micronemal proteins in Toxoplasma gondii suggests the occurrence of a stepwise process. Here, we show that the micronemal protein MIC8 of T. gondii is essential for the parasite to invade the host cell. When MIC8 is not present, a block in invasion is caused by the incapability of the parasite to form a moving junction with the host cell. We furthermore demonstrate that the cytosolic domain is crucial for the function of MIC8 and can not be functionally complemented by any other micronemal protein characterised so far, suggesting that MIC8 represents a novel, functionally distinct invasion factor in this apicomplexan parasite.
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Affiliation(s)
- Henning Kessler
- Hygieneinstitute, Department of Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
| | - Angelika Herm-Götz
- Hygieneinstitute, Department of Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
| | - Stephan Hegge
- Hygieneinstitute, Department of Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
| | - Manuel Rauch
- Hygieneinstitute, Department of Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, University of Geneva, CMU, 1, rue Michel-Servet 1211, Geneva 4, Switzerland
| | - Friedrich Frischknecht
- Hygieneinstitute, Department of Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
| | - Markus Meissner
- Hygieneinstitute, Department of Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
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21
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Mansfield JM, Paulnock DM. Genetic manipulation of African trypanosomes as a tool to dissect the immunobiology of infection. Parasite Immunol 2008; 30:245-53. [PMID: 18208450 DOI: 10.1111/j.1365-3024.2007.01003.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The variant surface glycoprotein (VSG) coat of African trypanosomes exhibits immunobiological functions distinct from its prominent role as a variant surface antigen. In order to address questions regarding immune stealth effects of VSG switch-variant coats, and the innate immune system activating effects of shed VSG substituents, several groups have genetically modified the ability of trypanosomes to express or release VSG during infection of the mammalian host. The role of mosaic surface coats expressed by VSG switch-variants (VSG double-expressors) in escaping early immune detection, and the role of VSG glycosylphosphatidylinositol (GPI) anchor substituents in regulating host immunity have been revealed, respectively, by stable co-expression of an exogenous VSG gene in trypanosomes expressing an endogenous VSG gene, and by knocking out the genetic locus for GPI-phospholipase C (PLC) that releases VSG from the membrane. Both approaches to genetic modification of African trypanosomes have suggested interesting and unexpected immunobiological effects associated with surface coat molecules.
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Affiliation(s)
- J M Mansfield
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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22
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Mohan A, Sullivan Jr WJ, Radivojac P, Dunker AK, Uversky VN. Intrinsic disorder in pathogenic and non-pathogenic microbes: discovering and analyzing the unfoldomes of early-branching eukaryotes. MOLECULAR BIOSYSTEMS 2008; 4:328-40. [DOI: 10.1039/b719168e] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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23
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Rapid control of protein level in the apicomplexan Toxoplasma gondii. Nat Methods 2007; 4:1003-5. [PMID: 17994029 DOI: 10.1038/nmeth1134] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2007] [Accepted: 10/23/2007] [Indexed: 11/08/2022]
Abstract
Analysis of gene function in apicomplexan parasites is limited by the absence of reverse genetic tools that allow easy and rapid modulation of protein levels. The fusion of a ligand-controlled destabilization domain (ddFKBP) to a protein of interest enables rapid and reversible protein stabilization in T. gondii. This allows an efficient functional analysis of proteins that have a dual role during host cell invasion and/or intracellular growth of the parasite.
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