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Klinger CM, Jimenez-Ruiz E, Mourier T, Klingl A, Lemgruber L, Pain A, Dacks JB, Meissner M. Evolutionary analysis identifies a Golgi pathway and correlates lineage-specific factors with endomembrane organelle emergence in apicomplexans. Cell Rep 2024; 43:113740. [PMID: 38363682 DOI: 10.1016/j.celrep.2024.113740] [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] [Received: 08/11/2023] [Revised: 12/20/2023] [Accepted: 01/18/2024] [Indexed: 02/18/2024] Open
Abstract
The organelle paralogy hypothesis (OPH) aims to explain the evolution of non-endosymbiotically derived organelles. It predicts that lineage-specific pathways or organelles should result when identity-encoding membrane-trafficking components duplicate and co-evolve. Here, we investigate the presence of such lineage-specific membrane-trafficking machinery paralogs in Apicomplexa, a globally important parasitic lineage. We are able to identify 18 paralogs of known membrane-trafficking machinery, in several cases co-incident with the presence of new endomembrane organelles in apicomplexans or their parent lineage, the Alveolata. Moreover, focused analysis of the apicomplexan Arf-like small GTPases (i.e., ArlX3) revealed a specific post-Golgi trafficking pathway. This pathway appears involved in delivery of proteins to micronemes and rhoptries, with knockdown demonstrating reduced invasion capacity. Overall, our data have identified an unforeseen post-Golgi trafficking pathway in apicomplexans and are consistent with the OPH mechanism acting to produce endomembrane pathways or organelles at various evolutionary stages across the alveolate lineage.
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Affiliation(s)
- Christen M Klinger
- Division of Infectious Diseases, Department of Medicine and Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada; Women and Children's Health Research Institute, University of Alberta, Edmonton, AB, Canada
| | - Elena Jimenez-Ruiz
- Experimental Parasitology, Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität, LMU, Munich, Germany
| | - Tobias Mourier
- Pathogen Genomics Laboratory, Bioscience Programme, Biological, and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Andreas Klingl
- Pflanzliche Entwicklungsbiologie, Biozentrum der Ludwig-Maximilians-Universität, Munich, Germany
| | - Leandro Lemgruber
- Cellular Analysis Facility, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Arnab Pain
- Pathogen Genomics Laboratory, Bioscience Programme, Biological, and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia; International Institute for Zoonosis Control, GI-CoRE, Hokkaido University, Sapporo, Japan
| | - Joel B Dacks
- Division of Infectious Diseases, Department of Medicine and Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada; Women and Children's Health Research Institute, University of Alberta, Edmonton, AB, Canada; Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic; Centre for Life's Origin and Evolution, Department of Genetics, Evolution & Environment, University College London, London, UK.
| | - Markus Meissner
- Experimental Parasitology, Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität, LMU, Munich, Germany.
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2
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Zhang L, Song Z, Li P, Song X, Tang X, Hu D. Molecular characterization and immune protective efficacy of 3 Eimeria tenella antigens. Poult Sci 2024; 103:103234. [PMID: 37980744 PMCID: PMC10685023 DOI: 10.1016/j.psj.2023.103234] [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] [Received: 08/31/2023] [Revised: 10/18/2023] [Accepted: 10/21/2023] [Indexed: 11/21/2023] Open
Abstract
Avian coccidiosis caused by Eimeria is a serious parasitic disease that poses a threat to the poultry industry. Currently, prevention and treatment mainly rely on the administration of anticoccidials and live oocyst vaccines. However, the prevalence of drug resistance and the inherent limitations of live vaccines have driven the development of novel vaccines. In this study, the surface protein (Et-SAG14), a previously annotated rhoptry protein (Eten5-B), and a gametocyte phosphoglucomutase (Et-PGM1) were characterized and the vaccine potential of the recombinant proteins were evaluated. Et-SAG14 was dispersed in the form of particles in the sporozoite and merozoite stages, whereas Et-PGM1 was distributed in the apical part of the sporozoite and merozoite stages. The previously annotated rhoptry Eten5-B was found not to be located in the rhoptry but distributed in the cytoplasm of sporozoites and merozoites. Immunization with rEten5-B significantly elevated host interferon gamma (IFN-γ) and interleukin 10 (IL-10) transcript levels and exhibited moderate anticoccidial effects with an anticoccidial index (ACI) of 161. Unexpectedly, both recombinant Et-SAG14 and Et-PGM1 immunization significantly reduced host IFN-γ and IL-10 transcription levels, and did not show protection against E. tenella challenge (ACI < 80). These results suggest that the rEten5-B protein can trigger immune protection against E. tenella and may be a potential and effective subunit vaccine for the control of coccidiosis in poultry.
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Affiliation(s)
- Lei Zhang
- College of Animal Science and Technology, Guangxi University, Nanning 530004, China
| | - Zhixuan Song
- College of Animal Science and Technology, Guangxi University, Nanning 530004, China
| | - Peiyao Li
- College of Animal Science and Technology, Guangxi University, Nanning 530004, China
| | - Xingju Song
- College of Animal Science and Technology, Guangxi University, Nanning 530004, China; Guangxi Zhuang Autonomous Region Engineering Research Center of Veterinary Biologics, Nanning 530004, China; Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, Nanning 530004, China
| | - Xinming Tang
- Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Dandan Hu
- College of Animal Science and Technology, Guangxi University, Nanning 530004, China; Guangxi Zhuang Autonomous Region Engineering Research Center of Veterinary Biologics, Nanning 530004, China; Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, Nanning 530004, China.
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3
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Herneisen AL, Li ZH, Chan AW, Moreno SNJ, Lourido S. Temporal and thermal profiling of the Toxoplasma proteome implicates parasite Protein Phosphatase 1 in the regulation of Ca 2+-responsive pathways. eLife 2022; 11:80336. [PMID: 35976251 PMCID: PMC9436416 DOI: 10.7554/elife.80336] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 08/17/2022] [Indexed: 11/13/2022] Open
Abstract
Apicomplexan parasites cause persistent mortality and morbidity worldwide through diseases including malaria, toxoplasmosis, and cryptosporidiosis. Ca2+ signaling pathways have been repurposed in these eukaryotic pathogens to regulate parasite-specific cellular processes governing the replicative and lytic phases of the infectious cycle, as well as the transition between them. Despite the presence of conserved Ca2+-responsive proteins, little is known about how specific signaling elements interact to impact pathogenesis. We mapped the Ca2+-responsive proteome of the model apicomplexan T. gondii via time-resolved phosphoproteomics and thermal proteome profiling. The waves of phosphoregulation following PKG activation and stimulated Ca2+ release corroborate known physiological changes but identify specific proteins operating in these pathways. Thermal profiling of parasite extracts identified many expected Ca2+-responsive proteins, such as parasite Ca2+-dependent protein kinases. Our approach also identified numerous Ca2+-responsive proteins that are not predicted to bind Ca2+, yet are critical components of the parasite signaling network. We characterized protein phosphatase 1 (PP1) as a Ca2+-responsive enzyme that relocalized to the parasite apex upon Ca2+ store release. Conditional depletion of PP1 revealed that the phosphatase regulates Ca2+ uptake to promote parasite motility. PP1 may thus be partly responsible for Ca2+-regulated serine/threonine phosphatase activity in apicomplexan parasites.
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Affiliation(s)
- Alice L Herneisen
- Whitehead Institute for Biomedical Research, Cambridge, United States
| | - Zhu-Hong Li
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, United States
| | - Alex W Chan
- Whitehead Institute for Biomedical Research, Cambridge, United States
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, United States
| | - Sebastian Lourido
- Whitehead Institute for Biomedical Research, Cambridge, United States
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Quach EV, Cao B, Babacarkhial E, Ho D, Sharma J, Guiton PS. Phosphoglucomutase 1 contributes to optimal cyst development in Toxoplasma gondii. BMC Res Notes 2022; 15:188. [PMID: 35597992 PMCID: PMC9123713 DOI: 10.1186/s13104-022-06073-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 05/11/2022] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE Toxoplasma gondii is a ubiquitous parasite of medical and veterinary importance; however, there exists no cure for chronic toxoplasmosis. Metabolic enzymes required for the production and maintenance of tissue cysts represent promising targets for novel therapies. Here, we use reverse genetics to investigate the role of Toxoplasma phosphoglucomutase 1, PGM1, in Toxoplasma growth and cystogenesis. RESULTS We found that disruption of pgm1 did not significantly affect Toxoplasma intracellular growth and the lytic cycle. pgm1-defective parasites could differentiate into bradyzoites and produced cysts containing amylopectin in vitro. However, cysts produced in the absence of pgm1 were significantly smaller than wildtype. Together, our findings suggest that PGM1 is dispensable for in vitro growth but contributes to optimal Toxoplasma cyst development in vitro, thereby necessitating further investigation into the function of this enzyme in Toxoplasma persistence in its host.
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Affiliation(s)
- Emily V Quach
- Department of Biology, Laney College, Oakland, CA, USA
| | - Binh Cao
- School of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Edres Babacarkhial
- Department of Biological Sciences, California State University East Bay, Hayward, CA, USA
| | - Daniel Ho
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - Janak Sharma
- Department of Biological Sciences, California State University East Bay, Hayward, CA, USA
| | - Pascale S Guiton
- Department of Biological Sciences, California State University East Bay, Hayward, CA, USA.
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Loubens M, Vincensini L, Fernandes P, Briquet S, Marinach C, Silvie O. Plasmodium sporozoites on the move: Switching from cell traversal to productive invasion of hepatocytes. Mol Microbiol 2021; 115:870-881. [PMID: 33191548 PMCID: PMC8247013 DOI: 10.1111/mmi.14645] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/10/2020] [Accepted: 11/11/2020] [Indexed: 12/18/2022]
Abstract
Parasites of the genus Plasmodium, the etiological agent of malaria, are transmitted through the bite of anopheline mosquitoes, which deposit sporozoites into the host skin. Sporozoites migrate through the dermis, enter the bloodstream, and rapidly traffic to the liver. They cross the liver sinusoidal barrier and traverse several hepatocytes before switching to productive invasion of a final one for replication inside a parasitophorous vacuole. Cell traversal and productive invasion are functionally independent processes that require proteins secreted from specialized secretory organelles known as micronemes. In this review, we summarize the current understanding of how sporozoites traverse through cells and productively invade hepatocytes, and discuss the role of environmental sensing in switching from a migratory to an invasive state. We propose that timely controlled secretion of distinct microneme subsets could play a key role in successful migration and infection of hepatocytes. A better understanding of these essential biological features of the Plasmodium sporozoite may contribute to the development of new strategies to fight against the very first and asymptomatic stage of malaria.
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Affiliation(s)
- Manon Loubens
- Centre d’Immunologie et des Maladies InfectieusesSorbonne Université, INSERM, CNRS, CIMI‐ParisParisFrance
| | - Laetitia Vincensini
- Centre d’Immunologie et des Maladies InfectieusesSorbonne Université, INSERM, CNRS, CIMI‐ParisParisFrance
| | - Priyanka Fernandes
- Centre d’Immunologie et des Maladies InfectieusesSorbonne Université, INSERM, CNRS, CIMI‐ParisParisFrance
| | - Sylvie Briquet
- Centre d’Immunologie et des Maladies InfectieusesSorbonne Université, INSERM, CNRS, CIMI‐ParisParisFrance
| | - Carine Marinach
- Centre d’Immunologie et des Maladies InfectieusesSorbonne Université, INSERM, CNRS, CIMI‐ParisParisFrance
| | - Olivier Silvie
- Centre d’Immunologie et des Maladies InfectieusesSorbonne Université, INSERM, CNRS, CIMI‐ParisParisFrance
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Dubois DJ, Soldati-Favre D. Biogenesis and secretion of micronemes in Toxoplasma gondii. Cell Microbiol 2019; 21:e13018. [PMID: 30791192 DOI: 10.1111/cmi.13018] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 02/11/2019] [Accepted: 02/17/2019] [Indexed: 12/20/2022]
Abstract
One of the hallmarks of the parasitic phylum of Apicomplexa is the presence of highly specialised, apical secretory organelles, called the micronemes and rhoptries that play critical roles in ensuring survival and dissemination. Upon exocytosis, the micronemes release adhesin complexes, perforins, and proteases that are crucially implicated in egress from infected cells, gliding motility, migration across biological barriers, and host cell invasion. Recent studies on Toxoplasma gondii and Plasmodium species have shed more light on the signalling events and the machinery that trigger microneme secretion. Intracellular cyclic nucleotides, calcium level, and phosphatidic acid act as key mediators of microneme exocytosis, and several downstream effectors have been identified. Here, we review the key steps of microneme biogenesis and exocytosis, summarising the still fractal knowledge at the molecular level regarding the fusion event with the parasite plasma membrane.
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Affiliation(s)
- David J Dubois
- Department of Microbiology and Molecular Medicine, University of Geneva CMU, Geneva, Switzerland
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, University of Geneva CMU, Geneva, Switzerland
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Two Phosphoglucomutase Paralogs Facilitate Ionophore-Triggered Secretion of the Toxoplasma Micronemes. mSphere 2017; 2:mSphere00521-17. [PMID: 29202046 PMCID: PMC5705807 DOI: 10.1128/msphere.00521-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 11/05/2017] [Indexed: 12/28/2022] Open
Abstract
Ca2+-dependent exocytosis is essential for the life cycle of apicomplexan parasites. Toxoplasma gondii harbors a phosphoglucomutase (PGM) ortholog, PRP1, previously associated with Ca2+-dependent microneme secretion. Here it is shown that genetic deletion of either PRP1, its PGM2 ortholog, or both genes is dispensable for the parasite’s lytic cycle, including host cell egress and invasion. Depletion of the proteins abrogated high Ca2+-mediated microneme secretion induced by the ionophore A23187; however, the constitutive and phosphatidic acid-mediated release remained unaffected. Secretion mediated by the former pathway is not essential for tachyzoite survival or acute in vivo infection in the mice. Paralogs of the widely prevalent phosphoglucomutase (PGM) protein called parafusin function in calcium (Ca2+)-mediated exocytosis across eukaryotes. In Toxoplasma gondii, the parafusin-related protein 1 (PRP1) has been associated with Ca2+-dependent microneme organelle secretion required for essential processes like host cell invasion and egress. Using reverse genetics, we observed PRP1 to be dispensable for completion of the lytic cycle, including host cell invasion and egress by the parasite. However, the absence of the gene affected increased microneme release triggered by A23187, a Ca2+ ionophore used to raise the cytoplasmic Ca2+ concentration mimicking the physiological role of Ca2+ during invasion and egress. The basal levels of constitutive microneme release in extracellular parasites and phosphatidic acid-triggered microneme secretion were unaffected in the mutant. The phenotype of the deletion mutant of the second PGM-encoding gene in Toxoplasma, PGM2, was similar to the phenotype of the PRP1 deletion mutant. Furthermore, the ability of the tachyzoites to induce acute infection in the mice remained normal in the absence of both PGM paralogs. Our data thus reveal that the microneme secretion upon high Ca2+ flux is facilitated by the Toxoplasma PGM paralogs, PRP1 and PGM2. However, this protein-mediated release is neither essential for lytic cycle completion nor for acute virulence of the parasite. IMPORTANCE Ca2+-dependent exocytosis is essential for the life cycle of apicomplexan parasites. Toxoplasma gondii harbors a phosphoglucomutase (PGM) ortholog, PRP1, previously associated with Ca2+-dependent microneme secretion. Here it is shown that genetic deletion of either PRP1, its PGM2 ortholog, or both genes is dispensable for the parasite’s lytic cycle, including host cell egress and invasion. Depletion of the proteins abrogated high Ca2+-mediated microneme secretion induced by the ionophore A23187; however, the constitutive and phosphatidic acid-mediated release remained unaffected. Secretion mediated by the former pathway is not essential for tachyzoite survival or acute in vivo infection in the mice.
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8
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Toxoplasma gondii Cyclic AMP-Dependent Protein Kinase Subunit 3 Is Involved in the Switch from Tachyzoite to Bradyzoite Development. mBio 2016; 7:mBio.00755-16. [PMID: 27247232 PMCID: PMC4895117 DOI: 10.1128/mbio.00755-16] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Toxoplasma gondii is an obligate intracellular apicomplexan parasite that infects warm-blooded vertebrates, including humans. Asexual reproduction in T. gondii allows it to switch between the rapidly replicating tachyzoite and quiescent bradyzoite life cycle stages. A transient cyclic AMP (cAMP) pulse promotes bradyzoite differentiation, whereas a prolonged elevation of cAMP inhibits this process. We investigated the mechanism(s) by which differential modulation of cAMP exerts a bidirectional effect on parasite differentiation. There are three protein kinase A (PKA) catalytic subunits (TgPKAc1 to -3) expressed in T. gondii. Unlike TgPKAc1 and TgPKAc2, which are conserved in the phylum Apicomplexa, TgPKAc3 appears evolutionarily divergent and specific to coccidian parasites. TgPKAc1 and TgPKAc2 are distributed in the cytomembranes, whereas TgPKAc3 resides in the cytosol. TgPKAc3 was genetically ablated in a type II cyst-forming strain of T. gondii (PruΔku80Δhxgprt) and in a type I strain (RHΔku80Δhxgprt), which typically does not form cysts. The Δpkac3 mutant exhibited slower growth than the parental and complemented strains, which correlated with a higher basal rate of tachyzoite-to-bradyzoite differentiation. 3-Isobutyl-1-methylxanthine (IBMX) treatment, which elevates cAMP levels, maintained wild-type parasites as tachyzoites under bradyzoite induction culture conditions (pH 8.2/low CO2), whereas the Δpkac3 mutant failed to respond to the treatment. This suggests that TgPKAc3 is the factor responsible for the cAMP-dependent tachyzoite maintenance. In addition, the Δpkac3 mutant had a defect in the production of brain cysts in vivo, suggesting that a substrate of TgPKAc3 is probably involved in the persistence of this parasite in the intermediate host animals. Toxoplasma gondii is one of the most prevalent eukaryotic parasites in mammals, including humans. Parasites can switch from rapidly replicating tachyzoites responsible for acute infection to slowly replicating bradyzoites that persist as a latent infection. Previous studies have demonstrated that T. gondii cAMP signaling can induce or suppress bradyzoite differentiation, depending on the strength and duration of cAMP signal. Here, we report that TgPKAc3 is responsible for cAMP-dependent tachyzoite maintenance while suppressing differentiation into bradyzoites, revealing one mechanism underlying how this parasite transduces cAMP signals during differentiation.
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Satir BH, Wyroba E, Liu L, Lethan M, Satir P, Christensen ST. Evolutionary implications of localization of the signaling scaffold protein parafusin to both cilia and the nucleus. Cell Biol Int 2014; 39:136-45. [PMID: 25044011 DOI: 10.1002/cbin.10337] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 07/11/2014] [Indexed: 11/08/2022]
Abstract
Parafusin (PFUS), a 63 kDa protein first discovered in the eukaryote Paramecium and known for its role in apicomplexan exocytosis, provides a model for the common origin of cellular systems employing scaffold proteins for targeting and signaling. PFUS is closely related to eubacterial rather than archeal phosphoglucomutases (PGM) - as we proved by comparison of their 88 sequences - but has no PGM activity. Immunofluorescence microscopy analysis with a PFUS-specific peptide antibody showed presence of this protein around the base region of primary cilia in a variety of mammalian cell types, including mouse embryonic (MEFs) and human foreskin fibroblasts (hFFs), human carcinoma stem cells (NT-2 cells), and human retinal pigment epithelial (RPE) cells. Further, PFUS localized to the nucleus of fibroblasts, and prominently to nucleoli of MEFs. Localization studies were confirmed by Western blot analysis, showing that the PFUS antibody specifically recognizes a single protein of ca. 63 kDa in both cytoplasmic and nuclear fractions. Finally, immunofluorescence microscopy analysis showed that PFUS localized to nuclei and cilia in Paramecium. These results support the suggestion that PFUS plays a role in signaling between nucleus and cilia, and that the cilium and the nucleus both evolved around the time of eukaryotic emergence. We hypothesize that near the beginnings of eukaryotic cell evolution, scaffold proteins such as PFUS arose as peripheral membrane protein identifiers for cytoplasmic membrane trafficking and were employed similarly during the subsequent evolution of exocytic, nuclear transport, and ciliogenic mechanisms.
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Affiliation(s)
- Birgit Hegner Satir
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Jack and Pearl Resnick Campus, 1300 Morris Park Avenue, Forchheimer Building, Bronx, NY, 10461, USA
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Evolution of apicomplexan secretory organelles. Int J Parasitol 2012; 42:1071-81. [PMID: 23068912 DOI: 10.1016/j.ijpara.2012.09.009] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 09/16/2012] [Accepted: 09/17/2012] [Indexed: 12/26/2022]
Abstract
The alveolate superphylum includes many free-living and parasitic organisms, which are united by the presence of alveolar sacs lying proximal to the plasma membrane, providing cell structure. All species comprising the apicomplexan group of alveolates are parasites and have adapted to the unique requirements of the parasitic lifestyle. Here the evolution of apicomplexan secretory organelles that are involved in the critical process of egress from one cell and invasion of another is explored. The variations within the Apicomplexa and how these relate to species-specific biology will be discussed. In addition, recent studies have identified specific calcium-sensitive molecules that coordinate the various events and regulate the release of these secretory organelles within apicomplexan parasites. Some aspects of this machinery are conserved outside the Apicomplexa, and are beginning to elucidate the conserved nature of the machinery. Briefly, the relationship of this secretion machinery within the Apicomplexa will be discussed, compared with free-living and predatory alveolates, and how these might have evolved from a common ancestor.
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11
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Plattner H, Sehring IM, Mohamed IK, Miranda K, De Souza W, Billington R, Genazzani A, Ladenburger EM. Calcium signaling in closely related protozoan groups (Alveolata): non-parasitic ciliates (Paramecium, Tetrahymena) vs. parasitic Apicomplexa (Plasmodium, Toxoplasma). Cell Calcium 2012; 51:351-82. [PMID: 22387010 DOI: 10.1016/j.ceca.2012.01.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 01/10/2012] [Accepted: 01/12/2012] [Indexed: 12/20/2022]
Abstract
The importance of Ca2+-signaling for many subcellular processes is well established in higher eukaryotes, whereas information about protozoa is restricted. Recent genome analyses have stimulated such work also with Alveolates, such as ciliates (Paramecium, Tetrahymena) and their pathogenic close relatives, the Apicomplexa (Plasmodium, Toxoplasma). Here we compare Ca2+ signaling in the two closely related groups. Acidic Ca2+ stores have been characterized in detail in Apicomplexa, but hardly in ciliates. Two-pore channels engaged in Ca2+-release from acidic stores in higher eukaryotes have not been stingently characterized in either group. Both groups are endowed with plasma membrane- and endoplasmic reticulum-type Ca2+-ATPases (PMCA, SERCA), respectively. Only recently was it possible to identify in Paramecium a number of homologs of ryanodine and inositol 1,3,4-trisphosphate receptors (RyR, IP3R) and to localize them to widely different organelles participating in vesicle trafficking. For Apicomplexa, physiological experiments suggest the presence of related channels although their identity remains elusive. In Paramecium, IP3Rs are constitutively active in the contractile vacuole complex; RyR-related channels in alveolar sacs are activated during exocytosis stimulation, whereas in the parasites the homologous structure (inner membrane complex) may no longer function as a Ca2+ store. Scrutinized comparison of the two closely related protozoan phyla may stimulate further work and elucidate adaptation to parasitic life. See also "Conclusions" section.
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Affiliation(s)
- H Plattner
- Department of Biology, University of Konstanz, P.O. Box 5560, 78457 Konstanz, Germany.
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12
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RNAi knockdown of parafusin inhibits the secretory pathway. Eur J Cell Biol 2011; 90:844-53. [DOI: 10.1016/j.ejcb.2011.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 05/27/2011] [Accepted: 06/11/2011] [Indexed: 11/30/2022] Open
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Imada M, Kawashima S, Kanehisa M, Takeuchi T, Asai T. Characterization of alpha-phosphoglucomutase isozymes from Toxoplasma gondii. Parasitol Int 2010; 59:206-10. [PMID: 20153838 DOI: 10.1016/j.parint.2010.01.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 12/04/2009] [Accepted: 01/31/2010] [Indexed: 11/16/2022]
Abstract
The Toxoplasma gondii genome project has revealed two putative isoforms (TgPGM-I and TgPGM-II) of alpha-phosphoglucomutase (EC 5.4.2.2). We obtained recombinant proteins of these isoforms from the Beverley strain of T. gondii and characterized their properties, particularly the kinetic properties of these isoforms. The specific activities of TgPGM-I and TgPGM-II for alpha-D-glucose 1-phosphate were 338+/-9 and 84+/-6micromol/min/mg protein, respectively, at 37 degrees C under optimal conditions. The Kcat and Km values of TgPGM-I were 398+/-11/s and 0.19+/-0.03mM and those for TgPGM-II were 93+/-7/s and 3.53+/-0.91mM, respectively, for alpha-d-glucose 1-phosphate. Magnesium ions were the most effective divalent cations for both the enzyme activities. The maximum activities of both the enzymes were obtained in the presence of more than 0.2mM alpha-D-glucose 1,6-bisphosphate. Although both enzymes were attached to the alpha-phosphohexomutase superfamily, amino acid sequence homology between TgPGM-I and TgPGM-II showed very low overall identity (25%). No alpha-phosphomannomutase (EC 5.4.2.8) activity was detected for either enzyme. The data indicated that TgPGM-I, but not TgPGM-II, may play an important role in alpha-D-glucose 6-phosphate production.
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Affiliation(s)
- Mihoko Imada
- Department of Tropical Medicine and Parasitology, School of Medicine, Keio University, Shinjuku-ku, Tokyo, Japan
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Liu L, Tucker SC, Satir BH. Toxoplasma PRP1 is an ortholog of parafusin (PFUS) in vesicle scaffold assembly in Ca2+-regulated exocytosis. Eur J Cell Biol 2009; 88:301-13. [DOI: 10.1016/j.ejcb.2008.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Revised: 10/06/2008] [Accepted: 10/08/2008] [Indexed: 11/25/2022] Open
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15
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Kats LM, Cooke BM, Coppel RL, Black CG. Protein Trafficking to Apical Organelles of Malaria Parasites - Building an Invasion Machine. Traffic 2007; 9:176-86. [PMID: 18047549 DOI: 10.1111/j.1600-0854.2007.00681.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Lev M Kats
- NHMRC Program in Malaria, Department of Microbiology, Monash University, Victoria 3800, Australia
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16
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Walker G. Meeting Report: 16th Meeting of the International Society for Evolutionary Protistology; Wrocław, Poland, August 2–5, 2006 (ISEP XVI). Protist 2007; 158:5-19. [PMID: 17166769 DOI: 10.1016/j.protis.2006.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Giselle Walker
- Museum of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
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17
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Abstract
Secretory processes play an important role on the biology and life cycles of parasitic protozoa. This review focus on basic aspects, from a cell biology perspective, of the secretion of (a) micronemes, rhoptries and dense granules in members of the Apicomplexa group, where these organelles are involved in the process of protozoan penetration into the host cell, survival within the parasitophorous vacuole and subsequent egress from the host cell, (b) the Maurer's cleft in Plasmodium, a structure involved in the secretion of proteins synthesized by the intravacuolar parasite and transported through vesicles to the erythrocyte surface, (c) the secretion of macromolecules into the flagellar pocket of trypanosomatids, and (d) the secretion of proteins which make the cyst wall of Giardia and Entamoeba, with the formation of encystation vesicles.
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Affiliation(s)
- Wanderley de Souza
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Ilha do Fundão, 21949-900 Rio de Janeiro, RJ, Brazil.
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18
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Abstract
We have recently proposed a mechanism to describe secretion, a fundamental process in all cells. That hypothesis, called porocytosis, embodies all available data and encompasses both forms of secretion, i.e., vesicular and constitutive. The current accepted view of exocytotic secretion involves the physical fusion of vesicle and plasma membranes; however, that hypothesized mechanism does not fit all available physiological data. Energetics of apposed lipid bilayers do not favor unfacilitated fusion. We consider that calcium ions (e.g., 10(-4) to 10(-3) M calcium in microdomains when elevated for 1 ms or less), whose mobility is restricted in space and time, establish salt bridges among adjacent lipid molecules. This establishes transient pores that span both the vesicle and plasma membrane lipid bilayers; the diameter of this transient pore would be approximately 1 nm (the diameter of a single lipid molecule). The lifetime of the transient pore is completely dependent on the duration of sufficient calcium ion levels. This places the porocytosis hypothesis for secretion squarely in the realm of the physical and physical chemical interactions of calcium and phospholipids and places mass action as the driving force for release of secretory material. The porocytosis hypothesis that we propose satisfies all of the observations and provides a framework to integrate our combined knowledge of vesicular and constitutive secretion.
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Affiliation(s)
- Robert B Silver
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, MI 48201, USA.
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19
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Kim K, Weiss LM. Toxoplasma gondii: the model apicomplexan. Int J Parasitol 2004; 34:423-32. [PMID: 15003501 PMCID: PMC3086386 DOI: 10.1016/j.ijpara.2003.12.009] [Citation(s) in RCA: 204] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2003] [Revised: 12/22/2003] [Accepted: 12/22/2003] [Indexed: 10/26/2022]
Abstract
Toxoplasma gondii is an obligate intracellular protozoan parasite which is a significant human and veterinary pathogen. Other members of the phylum Apicomplexa are also important pathogens including Plasmodium species (i.e. malaria), Eimeria species, Neospora, Babesia, Theileria and Cryptosporidium. Unlike most of these organisms, T. gondii is readily amenable to genetic manipulation in the laboratory. Cell biology studies are more readily performed in T. gondii due to the high efficiency of transient and stable transfection, the availability of many cell markers, and the relative ease with which the parasite can be studied using advanced microscopic techniques. Thus, for many experimental questions, T. gondii remains the best model system to study the biology of the Apicomplexa. Our understanding of the mechanisms of drug resistance, the biology of the apicoplast, and the process of host cell invasion has been advanced by studies in T. gondii. Heterologous expression of apicomplexan proteins in T. gondii has frequently facilitated further characterisation of proteins that could not be easily studied. Recent studies of Apicomplexa have been complemented by genome sequencing projects that have facilitated discovery of surprising differences in cell biology and metabolism between Apicomplexa. While results in T. gondii will not always be applicable to other Apicomplexa, T. gondii remains an important model system for understanding the biology of apicomplexan parasites.
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Affiliation(s)
- Kami Kim
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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20
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Matthiesen SH, Shenoy SM, Kim K, Singer RH, Satir BH. Role of the parafusin orthologue, PRP1, in microneme exocytosis and cell invasion in Toxoplasma gondii. Cell Microbiol 2003; 5:613-24. [PMID: 12925131 DOI: 10.1046/j.1462-5822.2003.00305.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The association of PRP1, a Paramecium parafusin orthologue, with Toxoplasma gondii micronemes, now confirmed by immunoelectron microscopy, has here been studied in relation to exocytosis and cell invasion. PRP1 becomes labelled in vivo by inorganic 32P and is dephosphorylated when ethanol is used to stimulate Ca2+-dependent exocytosis of the micronemes. The ethanol Ca2+-stimulated exocytosis is accompanied by translocation of PRP1 and microneme content protein (MIC3) from the apical end of the parasite. Immunoblotting showed that PRP1 is redistributed inside the parasite, while microneme content is secreted. To study whether similar changes occur during cell invasion, quantitative microscopy was performed during secretion, invasion and exit (egress) from the host cell. Time-course experiments showed that fluorescence intensities of PRP1 and MIC3 immediately after invasion were reduced 10-fold compared to preinvasion levels, indicating that PRP1 translocation and microneme secretion accompanies invasion. MIC3 regained fluorescence intensity and apical distribution after 15 min, while PRP1 recovered after 1 h. Intensity of both proteins then increased throughout the parasite division period until host cell lysis, suggesting the need to secrete microneme proteins to egress. These studies suggest that PRP1 associated with the secretory vesicle scaffold serves an important role in Ca2+-regulated exocytosis and cell invasion.
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Affiliation(s)
- Steen H Matthiesen
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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21
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Colón-Ramos DA, Salisbury JL, Sanders MA, Shenoy SM, Singer RH, García-Blanco MA. Asymmetric distribution of nuclear pore complexes and the cytoplasmic localization of beta2-tubulin mRNA in Chlamydomonas reinhardtii. Dev Cell 2003; 4:941-52. [PMID: 12791277 DOI: 10.1016/s1534-5807(03)00163-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Although it is generally accepted that nuclear architecture is an important determinant of nuclear activity, it is not clear whether cytoplasmic events, such as transcript localization and cell polarity, are affected by this architecture. Characterization of the nuclear architecture of the single-cell alga Chlamydomonas reinhardtii revealed a polarized nucleus, with nuclear pore complexes preferentially concentrated at the posterior side of the nucleus. Nuclear asymmetry was greatly exaggerated during the upregulation of genes encoding flagellar proteins, when nuclear pore complexes (NPCs) were observed to hyperpolarize to the posterior side of the nucleus while heterochromatin polarized to the anterior side. Interestingly, prior to deflagellation, the beta2-tubulin gene was preferentially located in the posterior region of the nucleus, and following deflagellation, beta2-tubulin transcripts accumulated posteriorly in polysome-rich cytoplasmic regions adjacent to the highest concentration of NPCs, suggesting a connection between nuclear architecture and cytoplasmic transcript localization.
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Affiliation(s)
- Daniel A Colón-Ramos
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
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22
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Satir BH, Matthiesen SH. Common signal transduction features in exocytosis in the alveolates Toxoplasma and Paramecium. Eur J Protistol 2003. [DOI: 10.1078/0932-4739-00010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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