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Krishnan D, Pandey M, Nayak S, Ghosh SK. Novel Insights into the Wattle and Daub Model of Entamoeba Cyst Wall Formation and the Importance of Actin Cytoskeleton. Pathogens 2023; 13:20. [PMID: 38251328 PMCID: PMC10818507 DOI: 10.3390/pathogens13010020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/12/2023] [Accepted: 12/20/2023] [Indexed: 01/23/2024] Open
Abstract
The "Wattle and Daub" model of cyst wall formation in Entamoeba invadens has been used to explain encystment in Entamoeba histolytica, the causal agent of amoebiasis, and this process could be a potential target for new antiamoebic drugs. In this study, we studied the morphological stages of chitin wall formation in E. invadens in more detail using fluorescent chitin-binding dyes and the immunolocalization of cyst wall proteins. It was found that chitin deposition was mainly initiated on the cell surface at a specific point or at different points at the same time. The cystic wall grew outward and gradually covered the entire surface of the cyst over time, following the model of Wattle and Daub. The onset of chitin deposition was guided by the localization of chitin synthase 1 to the plasma membrane, occurring on the basis of the Jacob lectin in the cell membrane. During encystation, F-actin was reorganized into the cortical region within the early stages of encystation and remained intact until the completion of the chitin wall. The disruption of actin polymerization in the cortical region inhibited proper wall formation, producing wall-less cysts or cysts with defective chitin walls, indicating the importance of the cortical actin cytoskeleton for proper cyst wall formation.
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Affiliation(s)
| | | | | | - Sudip K. Ghosh
- Department of Bioscience and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, India; (D.K.); (M.P.); (S.N.)
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2
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Probing the Peculiarity of EhRabX10, a pseudoRab GTPase, from the Enteric Parasite Entamoeba histolytica through In Silico Modeling and Docking Studies. BIOMED RESEARCH INTERNATIONAL 2021; 2021:9913625. [PMID: 34660804 PMCID: PMC8514894 DOI: 10.1155/2021/9913625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 09/08/2021] [Accepted: 09/23/2021] [Indexed: 11/17/2022]
Abstract
Entamoeba histolytica (Eh) is a pathogenic eukaryote that often resides silently in humans under asymptomatic stages. Upon indeterminate stimulus, it develops into fulminant amoebiasis that causes severe hepatic abscesses with 50% mortality. This neglected tropical pathogen relies massively on membrane modulation to flourish and cause disease; these modulations range from the phagocytic mode for food acquisition to a complex trogocytosis mechanism for tissue invasion. Rab GTPases form the largest branch of the Ras-like small GTPases, with a diverse set of roles across the eukaryotic kingdom. Rab GTPases are vital for the orchestration of membrane transport and the secretory pathway responsible for transporting the pathogenic effectors, such as cysteine proteases (EhCPs) which help in tissue invasion. Rab GTPases thus play a crucial role in executing the cytolytic effect of E. histolytica. First, they interact with Gal/Nac lectins required for adhering to the host cells, and then, they assist in the secretion of EhCPs. Additionally, amoebic Rab GTPases are vital for encystation because substantial vesicular trafficking is required to create dormant amoebic cysts. These cysts are the infective agent and help to spread the disease. The absence of a "bonafide" vesicular transport machinery in Eh and the existence of a diverse repertoire of amoebic Rab GTPases (EhRab) hint at their contribution in supporting this atypical machinery. Here, we provide insights into a pseudoRab GTPase, EhRabX10, by performing physicochemical analysis, predictive 3D structure modeling, protein-protein interaction studies, and in silico molecular docking. Our group is the first one to classify EhRabX10 as a pseudoRab GTPase with four nonconserved G-motifs. It possesses the basic fold of the P-loop containing nucleotide hydrolases. Through this in silico study, we provide an introduction to the characterization of the atypical EhRabX10 and set the stage for future explorations into the mechanisms of nucleotide recognition, binding, and hydrolysis employed by the pseudoEhRab GTPase family.
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3
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Talamás-Lara D, Acosta-Virgen K, Chávez-Munguía B, Lagunes-Guillén A, Salazar-Villatoro L, Espinosa-Cantellano M, Martínez-Palomo A. Golgi apparatus components in Entamoeba histolytica and Entamoeba dispar after monensin treatment. Microsc Res Tech 2021; 84:1887-1896. [PMID: 33675108 DOI: 10.1002/jemt.23745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 01/23/2021] [Accepted: 02/19/2021] [Indexed: 11/07/2022]
Abstract
Highly dynamic ribosomes, glycogen granules, thinly fibrillar material, and multiple membrane-bound vesicles are embedded in the matrix-rich cytoplasm of Entamoeba spp. trophozoites. The absence of a Golgi apparatus in these amoebae has been commonly accepted. Here we challenge this observation by incubating Entamoeba histolytica and Entamoeba dispar with monensin, an ionophore that produces swelling of the Golgi apparatus. We observe changes in the trophozoites through standard transmission electron microscopy, cryofixation and cryosubstitution, and analyze the label and expression of known resident proteins of the cis-GM130 and trans-TGN38 Golgi network through confocal microscopy and Western blot assays. Cryosubstitution and standard methods using the treatment, preserved membranous lamellae resembling Golgi components. GM130 and TGN38 Golgi antigens were found by immunoelectron, immunoblot, and co-localization by confocal microscopy using the reagent NBD C6-ceramide. Our results indicate that previously undetected Golgi apparatus components are present in the cytoplasm of E. histolytica and E. dispar.
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Affiliation(s)
- Daniel Talamás-Lara
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, Mexico
| | - Karla Acosta-Virgen
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, Mexico
| | - Bibiana Chávez-Munguía
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, Mexico
| | - Anel Lagunes-Guillén
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, Mexico
| | - Lizbeth Salazar-Villatoro
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, Mexico
| | - Martha Espinosa-Cantellano
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, Mexico
| | - Adolfo Martínez-Palomo
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Mexico City, Mexico
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4
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EhRab21 associates with the Golgi apparatus in Entamoeba histolytica. Parasitol Res 2020; 119:1629-1640. [PMID: 32219551 DOI: 10.1007/s00436-020-06667-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 03/15/2020] [Indexed: 01/12/2023]
Abstract
Rab proteins constitute the largest group of small GTPases and act as molecular switches in a wide variety of cellular processes, including proliferation, cytoskeleton assembly, and membrane trafficking in all eukaryotic cells. Rab21 has been reported in several eukaryotic cells, and our results suggest that in Entamoeba histolytica, Rab21 is involved in the vesicular traffic associated with the Golgi apparatus, where its function appears to be important to maintain the structure of this organelle. In addition, proteins such as Rab1A and Sec24, identified in this work associated with EhRab21, participate in the traffic of COPII vesicles from the endoplasmic reticulum to the Golgi apparatus and are necessary to maintain the latter's structure in human cells. In addition, EhRab21 probably affects the lysosome biogenesis, as indicated by an increase in the number of lysosomes as a result of the increase in EhRab21 activity. The participation of EhRab21 in the pathogenesis of amebiasis was verified on the amoebic liver abscess formation model using hamsters (Mesocricetus auratus), in which the overexpression of EhRab21Q64L (positive dominant mutant protein) decreased the number of liver abscesses formed.
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5
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Walters HA, Welter BH, Sullivan WJ, Temesvari LA. Phosphorylation of eukaryotic initiation factor-2α in response to endoplasmic reticulum and nitrosative stress in the human protozoan parasite, Entamoeba histolytica. Mol Biochem Parasitol 2019; 234:111223. [PMID: 31568804 PMCID: PMC6886254 DOI: 10.1016/j.molbiopara.2019.111223] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 09/20/2019] [Accepted: 09/23/2019] [Indexed: 12/25/2022]
Abstract
Entamoeba histolytica is an intestinal parasite infecting over 50 million people worldwide and is the causative agent of amebic dysentery and amoebic liver abscess. In the human host, E. histolytica experiences stress brought on by nutrient deprivation and the host immune response. To be a successful parasite, E. histolytica must counter the stress; therefore, understanding the stress response may uncover new drug targets. In many systems, the stress response includes down-regulation of protein translation, which is regulated by phosphorylation of eukaryotic initiation factor (eIF-2α). Previous work has demonstrated that phosphorylation of the E. histolytica eIF-2α (EheIF-2α) increases significantly when exposed to long-term serum starvation, oxidative stress, and long-term heat shock. However, the effects of reagents that are known to induce nitrosative or endoplasmic reticulum (ER) stresses, on EheIF-2α have yet to be evaluated. Nitrosative stress is part of the host's immune response and ER stress can be caused by several physiological or pathological factors. We treated E. histolytica cells with various reagents known to induce nitrosative stress (DPTA-NONOate and SNP) or ER stress (BFA and DTT). We examined the morphology of the ER, tracked phosphorylation of EheIF-2α, and assessed protein translation in control and stressed cells. While all four stress-inducing reagents caused a global reduction in protein translation, only DTT was capable of also inducing changes in the morphology of the ER (consistent with ER stress) and phosphorylation of EheIF-2α. This suggests that DTT authentically induces ER stress in E. histolytica and that this stress is managed by the eIF-2α-based system. This was supported by the observation that cells expressing a non-phosphorylatable version of eIF-2α were also highly sensitive to DTT-stress. Since protein translation decreased in the absence of phosphorylation of eIF-2α (after treatment with DPTA-NONOate, SNP or BFA), the data also indicate that there are alternative protein-translational control pathways in E. histolytica. Overall, our study further illuminates the stress response to nitrosative stress and ER stress in E. histolytica.
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Affiliation(s)
- Heather A Walters
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, 29634, United States; Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, South Carolina, 29634, United States
| | - Brenda H Welter
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, 29634, United States; Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, South Carolina, 29634, United States
| | - William J Sullivan
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, 46202, United States; Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, 46202, United States
| | - Lesly A Temesvari
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, 29634, United States; Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, South Carolina, 29634, United States.
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6
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Nakada-Tsukui K, Watanabe N, Maehama T, Nozaki T. Phosphatidylinositol Kinases and Phosphatases in Entamoeba histolytica. Front Cell Infect Microbiol 2019; 9:150. [PMID: 31245297 PMCID: PMC6563779 DOI: 10.3389/fcimb.2019.00150] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 04/23/2019] [Indexed: 12/11/2022] Open
Abstract
Phosphatidylinositol (PtdIns) metabolism is indispensable in eukaryotes. Phosphoinositides (PIs) are phosphorylated derivatives of PtdIns and consist of seven species generated by reversible phosphorylation of the inositol moieties at the positions 3, 4, and 5. Each of the seven PIs has a unique subcellular and membrane domain distribution. In the enteric protozoan parasite Entamoeba histolytica, it has been previously shown that the PIs phosphatidylinositol 3-phosphate (PtdIns3P), PtdIns(4,5)P2, and PtdIns(3,4,5)P3 are localized to phagosomes/phagocytic cups, plasma membrane, and phagocytic cups, respectively. The localization of these PIs in E. histolytica is similar to that in mammalian cells, suggesting that PIs have orthologous functions in E. histolytica. In contrast, the conservation of the enzymes that metabolize PIs in this organism has not been well-documented. In this review, we summarized the full repertoire of the PI kinases and PI phosphatases found in E. histolytica via a genome-wide survey of the current genomic information. E. histolytica appears to have 10 PI kinases and 23 PI phosphatases. It has a panel of evolutionarily conserved enzymes that generate all the seven PI species. However, class II PI 3-kinases, type II PI 4-kinases, type III PI 5-phosphatases, and PI 4P-specific phosphatases are not present. Additionally, regulatory subunits of class I PI 3-kinases and type III PI 4-kinases have not been identified. Instead, homologs of class I PI 3-kinases and PTEN, a PI 3-phosphatase, exist as multiple isoforms, which likely reflects that elaborate signaling cascades mediated by PtdIns(3,4,5)P3 are present in this organism. There are several enzymes that have the nuclear localization signal: one phosphatidylinositol phosphate (PIP) kinase, two PI 3-phosphatases, and one PI 5-phosphatase; this suggests that PI metabolism also has conserved roles related to nuclear functions in E. histolytica, as it does in model organisms.
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Affiliation(s)
- Kumiko Nakada-Tsukui
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Natsuki Watanabe
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan.,Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Tomohiko Maehama
- Division of Molecular and Cellular Biology, Graduate School of Medicine, Kobe University, Kobe, Japan
| | - Tomoyoshi Nozaki
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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7
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Herman EK, Yiangou L, Cantoni DM, Miller CN, Marciano-Cabral F, Anthonyrajah E, Dacks JB, Tsaousis AD. Identification and characterisation of a cryptic Golgi complex in Naegleria gruberi. J Cell Sci 2018; 131:jcs213306. [PMID: 29535209 PMCID: PMC5963838 DOI: 10.1242/jcs.213306] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 02/26/2018] [Indexed: 12/12/2022] Open
Abstract
Although the Golgi complex has a conserved morphology of flattened stacked cisternae in most eukaryotes, it has lost the stacked organisation in several lineages, raising the question of what range of morphologies is possible for the Golgi. In order to understand this diversity, it is necessary to characterise the Golgi in many different lineages. Here, we identify the Golgi complex in Naegleria, one of the first descriptions of an unstacked Golgi organelle in a non-parasitic eukaryote, other than fungi. We provide a comprehensive list of Golgi-associated membrane trafficking genes encoded in two species of Naegleria and show that nearly all are expressed in mouse-passaged N. fowleri cells. We then study distribution of the Golgi marker (Ng)CopB by fluorescence in Naegleria gruberi, identifying membranous structures that are disrupted by Brefeldin A treatment, consistent with Golgi localisation. Confocal and immunoelectron microscopy reveals that NgCOPB localises to tubular membranous structures. Our data identify the Golgi organelle for the first time in this major eukaryotic lineage, and provide the rare example of a tubular morphology, representing an important sampling point for the comparative understanding of Golgi organellar diversity.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Emily K Herman
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
| | - Lyto Yiangou
- Laboratory of Molecular and Evolutionary Parasitology, RAPID group, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
| | - Diego M Cantoni
- Laboratory of Molecular and Evolutionary Parasitology, RAPID group, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
| | - Christopher N Miller
- Laboratory of Molecular and Evolutionary Parasitology, RAPID group, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
| | - Francine Marciano-Cabral
- Department of Microbiology and Immunology, Virginia Commonwealth University, School of Medicine, 1101 E. Marshall St, Richmond, VA 23298-0678, USA
| | - Erin Anthonyrajah
- Laboratory of Molecular and Evolutionary Parasitology, RAPID group, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
| | - Joel B Dacks
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
| | - Anastasios D Tsaousis
- Laboratory of Molecular and Evolutionary Parasitology, RAPID group, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
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Pineda E, Perdomo D. Entamoeba histolytica under Oxidative Stress: What Countermeasure Mechanisms Are in Place? Cells 2017; 6:cells6040044. [PMID: 29160807 PMCID: PMC5755502 DOI: 10.3390/cells6040044] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 11/17/2017] [Accepted: 11/17/2017] [Indexed: 02/06/2023] Open
Abstract
Entamoeba histolytica is the causative agent of human amoebiasis; it affects 50 million people worldwide and causes approximately 100,000 deaths per year. Entamoeba histolytica is an anaerobic parasite that is primarily found in the colon; however, for unknown reasons, it can become invasive, breaching the gut barrier and migrating toward the liver causing amoebic liver abscesses. During the invasive process, it must maintain intracellular hypoxia within the oxygenated human tissues and cellular homeostasis during the host immune defense attack when it is confronted with nitric oxide and reactive oxygen species. But how? This review will address the described and potential mechanisms available to counter the oxidative stress generated during invasion and the possible role that E. histolytica’s continuous endoplasmic reticulum (Eh-ER) plays during these events.
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Affiliation(s)
- Erika Pineda
- Laboratory of Fundamental Microbiology and Pathogenicity (MFP), University of Bordeaux, CNRS UMR-5234, 33000 Bordeaux, France.
| | - Doranda Perdomo
- Laboratory of Fundamental Microbiology and Pathogenicity (MFP), University of Bordeaux, CNRS UMR-5234, 33000 Bordeaux, France.
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9
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Perdomo D, Manich M, Syan S, Olivo-Marin JC, Dufour AC, Guillén N. Intracellular traffic of the lysine and glutamic acid rich protein KERP1 reveals features of endomembrane organization in Entamoeba histolytica. Cell Microbiol 2016; 18:1134-52. [PMID: 26857352 DOI: 10.1111/cmi.12576] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Revised: 01/06/2016] [Accepted: 02/01/2016] [Indexed: 12/12/2022]
Abstract
The development of amoebiasis is influenced by the expression of the lysine and glutamic acid rich protein 1 (KERP1), a virulence factor involved in Entamoeba histolytica adherence to human cells. Up to date, it is unknown how the protein transits the parasite cytoplasm towards the plasma membrane, specially because this organism lacks a well-defined endoplasmic reticulum (ER) and Golgi apparatus. In this work we demonstrate that KERP1 is present at the cell surface and in intracellular vesicles which traffic in a pathway that is independent of the ER-Golgi anterograde transport. The intracellular displacement of vesicles enriched in KERP1 relies on the actin-rich cytoskeleton activities. KERP1 is also present in externalized vesicles deposited on the surface of human cells. We further report the interactome of KERP1 with its association to endomembrane components and lipids. The model for KERP1 traffic here proposed hints for the first time elements of the endocytic and exocytic paths of E. histolytica.
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Affiliation(s)
- Doranda Perdomo
- Cell Biology of Parasitism Unit, Institut Pasteur, Paris, France.,INSERM U786, Paris, France.,Sorbonne Paris Cité, Cellule Pasteur, Université Paris Diderot, Paris, France
| | - Maria Manich
- Cell Biology of Parasitism Unit, Institut Pasteur, Paris, France.,INSERM U786, Paris, France
| | - Sylvie Syan
- Cell Biology of Parasitism Unit, Institut Pasteur, Paris, France.,INSERM U786, Paris, France
| | | | - Alexandre C Dufour
- Bioimage Analysis Unit, Institut Pasteur, Paris, France.,CNRS UMR 3691, Paris, France
| | - Nancy Guillén
- Cell Biology of Parasitism Unit, Institut Pasteur, Paris, France.,INSERM U786, Paris, France
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Bahl S, Parashar S, Malhotra H, Raje M, Mukhopadhyay A. Functional Characterization of Monomeric GTPase Rab1 in the Secretory Pathway of Leishmania. J Biol Chem 2015; 290:29993-30005. [PMID: 26499792 DOI: 10.1074/jbc.m115.670018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Indexed: 12/20/2022] Open
Abstract
Leishmania secretes a large number of its effectors to the extracellular milieu. However, regulation of the secretory pathway in Leishmania is not well characterized. Here, we report the cloning, expression, and characterization of the Rab1 homologue from Leishmania. We have found that LdRab1 localizes in Golgi in Leishmania. To understand the role of LdRab1 in the secretory pathway of Leishmania, we have generated transgenic parasites overexpressing GFP-LdRab1:WT, GFP-LdRab1:Q67L (a GTPase-deficient dominant positive mutant of Rab1), and GFP-LdRab1:S22N (a GDP-locked dominant negative mutant of Rab1). Surprisingly, our results have shown that overexpression of GFP-LdRab1:Q67L or GFP-LdRab1:S22N does not disrupt the trafficking and localization of hemoglobin receptor in Leishmania. To determine whether the Rab1-dependent secretory pathway is conserved in parasites, we have analyzed the role of LdRab1 in the secretion of secretory acid phosphatase and Ldgp63 in Leishmania. Our results have shown that overexpression of GFP-LdRab1:Q67L or GFP-LdRab1:S22N significantly inhibits the secretion of secretory acid phosphatase by Leishmania. We have also found that overexpression of GFP-LdRab1:Q67L or GFP-LdRab1:S22N retains RFP-Ldgp63 in Golgi and blocks the secretion of Ldgp63, whereas the trafficking of RFP-Ldgp63 in GFP-LdRab1:WT-expressing cells is unaltered in comparison with control cells. Taken together, our results have shown that the Rab1-regulated secretory pathway is well conserved, and hemoglobin receptor trafficking follows an Rab1-independent secretory pathway in Leishmania.
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Affiliation(s)
- Surbhi Bahl
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India and
| | - Smriti Parashar
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India and
| | | | - Manoj Raje
- the Institute of Microbial Technology, Chandigarh 160036, India
| | - Amitabha Mukhopadhyay
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India and
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11
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Perdomo D, Aït-Ammar N, Syan S, Sachse M, Jhingan GD, Guillén N. Cellular and proteomics analysis of the endomembrane system from the unicellular Entamoeba histolytica. J Proteomics 2015; 112:125-40. [DOI: 10.1016/j.jprot.2014.07.034] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 07/11/2014] [Accepted: 07/18/2014] [Indexed: 12/27/2022]
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12
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Lee YA, Kim KA, Min A, Shin MH. Amoebic PI3K and PKC is required for Jurkat T cell death induced by Entamoeba histolytica. THE KOREAN JOURNAL OF PARASITOLOGY 2014; 52:355-65. [PMID: 25246714 PMCID: PMC4170031 DOI: 10.3347/kjp.2014.52.4.355] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Revised: 05/29/2014] [Accepted: 06/04/2014] [Indexed: 01/01/2023]
Abstract
The enteric protozoan parasite Entamoeba histolytica is the causative agent of human amebiasis. During infection, adherence of E. histolytica through Gal/GalNAc lectin on the surface of the amoeba can induce caspase-3-dependent or -independent host cell death. Phosphorylinositol 3-kinase (PI3K) and protein kinase C (PKC) in E. histolytica play an important function in the adhesion, killing, or phagocytosis of target cells. In this study, we examined the role of amoebic PI3K and PKC in amoeba-induced apoptotic cell death in Jurkat T cells. When Jurkat T cells were incubated with E. histolytica trophozoites, phosphatidylserine (PS) externalization and DNA fragmentation in Jurkat cells were markedly increased compared to those of cells incubated with medium alone. However, when amoebae were pretreated with a PI3K inhibitor, wortmannin before being incubated with E. histolytica, E. histolytica-induced PS externalization and DNA fragmentation in Jurkat cells were significantly reduced compared to results for amoebae pretreated with DMSO. In addition, pretreatment of amoebae with a PKC inhibitor, staurosporine strongly inhibited Jurkat T cell death. However, E. histolytica-induced cleavage of caspase-3, -6, and -7 were not inhibited by pretreatment of amoebae with wortmannin or staurosporin. In addition, we found that amoebic PI3K and PKC have an important role on amoeba adhesion to host compartment. These results suggest that amebic PI3K and PKC activation may play an important role in caspase-independent cell death in Entamoeba-induced apoptosis.
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Affiliation(s)
- Young Ah Lee
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Kyeong Ah Kim
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Arim Min
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Myeong Heon Shin
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea
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Wyrozumska P, Ashley JW, Ramanadham S, Liu Q, Garvey WT, Sztul E. Novel effects of Brefeldin A (BFA) in signaling through the insulin receptor (IR) pathway and regulating FoxO1-mediated transcription. CELLULAR LOGISTICS 2014; 4:e27732. [PMID: 24843827 PMCID: PMC4022606 DOI: 10.4161/cl.27732] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 01/02/2014] [Accepted: 01/03/2014] [Indexed: 12/19/2022]
Abstract
Brefeldin A (BFA) is a fungal metabolite best known for its ability to inhibit activation of ADP-ribosylation factor (Arf) and thereby inhibit secretory traffic. BFA also appears to regulate the trafficking of the GLUT4 glucose transporter by inducing its relocation from intracellular stores to the cell surface. Such redistribution of GLUT4 is normally regulated by insulin-mediated signaling. Hence, we tested whether BFA may intersect with the insulin pathway. We report that BFA causes the activation of the insulin receptor (IR), IRS-1, Akt-2, and AS160 components of the insulin pathway. The response is mediated through phosphoinositol-3-kinase (PI3K) and Akt kinase since the PI3K inhibitor wortmannin and the Akt inhibitors MK2206 and perifosine inhibit the BFA effect. BFA-mediated activation of the insulin pathway results in Akt-mediated phosphorylation of the insulin-responsive transcription factor FoxO1. This leads to nuclear exclusion of FoxO1 and a decrease in transcription of the insulin-responsive gene SIRT-1. Our findings suggest novel effects for BFA in signaling and transcription, and imply that BFA has multiple intracellular targets and can be used to regulate diverse cellular responses that include vesicular trafficking, signaling and transcription.
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Affiliation(s)
- Paulina Wyrozumska
- Department of Cell, Developmental and Integrative Biology; University of Alabama at Birmingham; Birmingham, AL USA
| | - Jason W Ashley
- Department of Cell, Developmental and Integrative Biology; University of Alabama at Birmingham; Birmingham, AL USA
| | - Sasanka Ramanadham
- Department of Cell, Developmental and Integrative Biology; University of Alabama at Birmingham; Birmingham, AL USA
| | - Qinglan Liu
- Department of Nutrition Sciences University of Alabama at Birmingham; Birmingham, AL USA
| | - W Timothy Garvey
- Department of Nutrition Sciences University of Alabama at Birmingham; Birmingham, AL USA
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology; University of Alabama at Birmingham; Birmingham, AL USA
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Wagner T, Dieckmann M, Jaeger S, Weggen S, Pietrzik CU. Stx5 is a novel interactor of VLDL-R to affect its intracellular trafficking and processing. Exp Cell Res 2013; 319:1956-1972. [DOI: 10.1016/j.yexcr.2013.05.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 04/10/2013] [Accepted: 05/13/2013] [Indexed: 11/30/2022]
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15
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Javier-Reyna R, Hernández-Ramírez V, González-Robles A, Galván-Mendoza I, Osorio-Trujillo C, Talamás-Rohana P. Rab7 and actin cytoskeleton participate during mobilization of β1EHFNR in fibronectin-stimulated Entamoeba histolyticatrophozoites. Microsc Res Tech 2011; 75:285-93. [DOI: 10.1002/jemt.21056] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Accepted: 06/12/2011] [Indexed: 01/12/2023]
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Entamoeba histolytica calreticulin: an endoplasmic reticulum protein expressed by trophozoites into experimentally induced amoebic liver abscesses. Parasitol Res 2010; 108:439-49. [PMID: 20922421 DOI: 10.1007/s00436-010-2085-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Accepted: 09/08/2010] [Indexed: 12/16/2022]
Abstract
Entamoeba histolytica calreticulin (EhCRT) is remarkably immunogenic in humans (90-100% of invasive amoebiasis patients). Nevertheless, the study of calreticulin in this protozoan is still in its early stages. The exact location, biological functions, and its role in pathogenesis are yet to be fully understood. The aim of the present work is to determine the location of EhCRT in virulent trophozoites in vivo and the expression of the Ehcrt gene during the development of experimentally induced amoebic liver abscesses (ALA) in hamsters. Antibodies against recombinant EhCRT were used for the immunolocalization of EhCRT in trophozoites through confocal microscopy; immunohistochemical assays were also performed on tissue sections of ALAs at different times after intrahepatic inoculation. The expression of the Ehcrt gene during the development of ALA was estimated through both in situ RT-PCR and real-time RT-PCR. Confocal assays of virulent trophozoites showed a distribution of EhCRT in the cytoplasmic vesicles of different sizes. Apparently, EhCRT is not exported into the hepatic tissue. Real-time RT-PCR demonstrated an over-expression of the Ehcrt gene at 30 min after trophozoite inoculation, reaching a peak at 1-2 h; thereafter, the expression fell sharply to its original levels. These results demonstrate for the first time in an in vivo model of ALA, the expression of Ehcrt gene in E. histolytica trophozoites and add evidence that support CRT as a resident protein of the ER in E. histolytica species. The in vivo experiments suggest that CRT may play an important role during the early stages of the host-parasite relationship, when the parasite is adapting to a new environment, although the protein seems to be constitutively synthesized. Moreover, trophozoites apparently do not export EhCRT into the hepatic tissue in ALA.
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Overexpression of a mutant form of EhRabA, a unique Rab GTPase of Entamoeba histolytica, alters endoplasmic reticulum morphology and localization of the Gal/GalNAc adherence lectin. EUKARYOTIC CELL 2009; 8:1014-26. [PMID: 19377040 DOI: 10.1128/ec.00030-09] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Entamoeba histolytica is a protozoan parasite that causes amoebic dysentery and liver abscess. Vesicle trafficking events, such as phagocytosis and delivery of plasma membrane proteins, have been implicated in pathogenicity. Rab GTPases are proteins whose primary function is to regulate vesicle trafficking; therefore, understanding the function of Rabs in this organism may provide insight into virulence. E. histolytica possesses a number of unique Rabs that exhibit limited homology to host Rabs. In this study we examined the function of one such Rab, EhRabA, by characterizing a mutant overexpressing a constitutively GTP-bound version of the protein. Overexpression of mutant EhRabA resulted in decreased adhesion to and phagocytosis of human red blood cells and in the appearance of large tubular organelles that could be stained with endoplasmic reticulum (ER)-specific but not Golgi complex-specific antibodies. Consistent with the adhesion defect, two subunits of a cell surface adhesin, the galactose/N-acetylgalactosamine lectin, were mislocalized to the novel organelle. A cysteine protease, EhCP2, was also localized to the ER-like compartment in the mutant; however, the localization of two additional cell surface proteins, Igl and SREHP, remained unchanged in the mutant. The phenotype of the mutant could be recapitulated by treatment with brefeldin A, a cellular toxin that disrupts ER-to-Golgi apparatus vesicle traffic. This suggests that EhRabA influences vesicle trafficking pathways that are also sensitive to brefeldin A. Together, the data indicate that EhRabA directly or indirectly influences the morphology of secretory organelles and regulates trafficking of a subset of secretory proteins in E. histolytica.
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Mitra BN, Saito-Nakano Y, Nakada-Tsukui K, Sato D, Nozaki T. Rab11B small GTPase regulates secretion of cysteine proteases in the enteric protozoan parasiteEntamoeba histolytica. Cell Microbiol 2007; 9:2112-25. [PMID: 17441984 DOI: 10.1111/j.1462-5822.2007.00941.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Vesicular trafficking plays a pivotal role in the virulence of the enteric protozoan parasite Entamoeba histolytica. In the present study, we showed that one isotype of the small GTPase Rab11, EhRab11B, plays a central role in the secretion of a major virulence factor, cysteine proteases. EhRab11B did not colocalize with markers for the endoplasmic reticulum, early endosomes and lysosomes, but was partially associated with non-acidified vesicles in the endocytic pathway, likely recycling endosomes. Overexpression of EhRab11B resulted in a remarkable increase in both intracellular and secreted cysteine protease activity, concomitant with an augmentation of cytolytic activity as demonstrated by an increased ability to destroy mammalian cells. The oversecretion of cysteine proteases with EhRab11B overexpression was neither sensitive to brefeldin A nor specific to a certain cysteine protease species (e.g. CP1, 2 or 5), suggesting that these three major cysteine proteases are trafficked via an EhRab11B-associated secretory pathway, which is distinct from the classical brefeldin-sensitive pathway. Overexpression of EhRab11B also enhanced exocytosis of the incorporated fluid-phase marker, supporting the notion that it is involved in recycling. This is the first report demonstrating that Rab11 plays a central role in the transport and secretion of pathogenic factors.
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Affiliation(s)
- Biswa Nath Mitra
- Department of Parasitology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-851, Japan
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Sokolova YY, Snigirevskaya ES, Komissarchik YY. The Golgi apparatus in parasitic protists. ACTA ACUST UNITED AC 2007. [DOI: 10.1134/s1990519x07040037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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20
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Franco-Barraza J, Zamudio-Meza H, Franco E, del Carmen Domínguez-Robles M, Villegas-Sepúlveda N, Meza I. Rho signaling inEntamoeba histolytica modulates actomyosin-dependent activities stimulated during invasive behavior. ACTA ACUST UNITED AC 2006; 63:117-31. [PMID: 16421927 DOI: 10.1002/cm.20105] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Interaction of Entamoeba histolytica trophozoites with target cells and substrates activates signaling pathways in the parasite. Phosphorylation cascades triggered by phospho-inositide and adenyl-cyclase-dependent pathways modulate reorganization of the actin cytoskeleton to form structures that facilitate adhesion. In contrast, little is known about participation of Rho proteins and Rho signaling in actin rearrangements. We report here the in vivo expression of at least one Rho protein in trophozoites, whose activation induced actin reorganization and actin-myosin interaction. Antibodies to EhRhoA1 recombinant protein mainly localized Rho in the cytosol of nonactivated amoebae, but it was translocated to vesicular membranes and to some extent to the plasma membrane after treatment with lysophosphatidic acid (LPA), a specific agonist of Rho activation. Activated Rho was identified in LPA-treated trophozoites. LPA induced striking polymerization of actin into distinct dynamic structures. Disorganization of these structures by inhibition of Rho effector, Rho-kinase (ROCK), and by ML-7, an inhibitor of myosin light chain kinase dependent phosphorylation of myosin light chain, suggested that the actin structures also contained myosin. LPA stimulated concanavalin-A-mediated formation of caps, chemotaxis, invasion of extracellular matrix substrates, and erythrophagocytosis, but not binding to fibronectin. ROCK inhibition impaired LPA-stimulated functions and to some extent adhesion to fibronectin. Similar results were obtained with ML-7. These data suggest the presence and operation of Rho-signaling pathways in E. histolytica, that together with other, already described, signaling routes modulate actomyosin-dependent motile processes, particularly stimulated during invasive behavior.
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Ramos MA, Sanchez-Lopez R, Mares RE, Olvera F, Alagón A. Identification of an Entamoeba histolytica gene encoding a protein disulfide isomerase that functionally complements the dsbA mutation in Escherichia coli. Mol Biochem Parasitol 2005; 143:236-40. [PMID: 15990181 DOI: 10.1016/j.molbiopara.2005.04.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Revised: 04/13/2005] [Accepted: 04/20/2005] [Indexed: 10/25/2022]
Affiliation(s)
- Marco A Ramos
- Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, Calzada Tecnológico 14418, Tijuana, Baja California 22390, México
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22
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Davis PH, Zhang Z, Chen M, Zhang X, Chakraborty S, Stanley SL. Identification of a family of BspA like surface proteins of Entamoeba histolytica with novel leucine rich repeats. Mol Biochem Parasitol 2005; 145:111-6. [PMID: 16199101 PMCID: PMC1382194 DOI: 10.1016/j.molbiopara.2005.08.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2005] [Revised: 07/26/2005] [Accepted: 08/29/2005] [Indexed: 11/25/2022]
Affiliation(s)
- Paul H Davis
- Department of Medicine, Washington University School of Medicine, St Louis, Missouri 63110, USA
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Bredeston LM, Caffaro CE, Samuelson J, Hirschberg CB. Golgi and Endoplasmic Reticulum Functions Take Place in Different Subcellular Compartments of Entamoeba histolytica. J Biol Chem 2005; 280:32168-76. [PMID: 16027148 DOI: 10.1074/jbc.m507035200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Entamoeba histolytica is a protozoan parasite that causes dysentery in developing countries of Africa, Asia, and Latin America. The lack of a defined Golgi apparatus in E. histolytica as well as in other protists led to the hypothesis that they had evolved prior to the acquisition of such organelle even though glycoproteins, glycolipids, and antigens have been detected, the latter of which react with antibodies against Golgi apparatus proteins of higher eukaryotes. We here provide direct evidence for Golgi apparatus-like functions in E. histolytica as well as for components of glycoprotein folding quality control. Using a combination of bioinformatic, cell biological, and biochemical approaches we have (a) cloned and expressed the E. histolytica UDP-galactose transporter in Saccharomyces cerevisiae; its K(m) for UDP-galactose is 2.9 microm; (b) characterized vesicles in an extract of the above protist, which transport UDP-galactose into their lumen with a K(m) of 2.7 microm;(c) detected galactosyltransferase activity(ies) in the lumen of the above vesicles with the K(m) for UDP-galactose, using endogenous acceptors, being 93 microm;(d) measured latent apyrase activities in the above vesicles, suggesting they are in the lumen; (e) characterized UDP-glucose transport activities in Golgi apparatus and endoplasmic reticulum-like vesicles with K(m)s for UDP-glucose of approximately 2-4 microm. Although the endoplasmic reticulum-like fraction showed UDP-glucose: glycoprotein glucosyltransferase activity, the Golgi apparatus-like fraction did not. This fraction contained other glucosyltransferases. Together, these studies demonstrate that E. histolytica has different vesicles that play a role in protein glycosylation and folding quality control, analogous to the above organellar functions of higher eukaryotes.
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Affiliation(s)
- Luis M Bredeston
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Massachusetts 02118-2492, USA
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Salgado M, Villagómez-Castro JC, Rocha-Rodríguez R, Sabanero-López M, Ramos MA, Alagón A, López-Romero E, Sánchez-López R. Entamoeba histolytica: biochemical and molecular insights into the activities within microsomal fractions. Exp Parasitol 2005; 110:363-73. [PMID: 15913610 DOI: 10.1016/j.exppara.2005.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2004] [Revised: 03/30/2005] [Accepted: 04/02/2005] [Indexed: 11/22/2022]
Abstract
One of the most fascinating aspects of the Entamoeba histolytica trophozoite ultrastructure is the lack of a typical secretory pathway, particularly of rough endoplasmic reticulum and Golgi system, in a cell with such a high secretory activity. Here, we describe the isolation of amoeba cell structures containing ER-typical activities. Following isopycnic centrifugation of plasma membrane-free extracts, microsomes enriched in enzymatic activities such as dolichol-P-mannose synthase (DPMS; EC 2.4.1.83), UDP-GlcNAc:dolichol-P GlcNAc-1-P transferase (NAGPT; EC 2.7.8.15), and UDP-D-GlcNAc:dolichol-PP GlcNAc (NAGT; EC 2.4.1.141) were resolved from phagolysosomal fractions. Sec61alpha-subunit, an ER-marker involved in the translocation of nascent proteins to the ER, was found to co-fractionate with DPMS activity indicating that they are contained in microsomes with a similar density. Further, we optimized conditions for trophozoite homogenization and differential centrifugation that resulted in the separation of a 57,000 g-sedimenting microsomal fraction containing EhSec61alpha-subunit, EhDPMS, and EhPDI (protein disulfide isomerase, a soluble marker of the lumen of the ER). A relevant observation was the lack of ER markers associated to the nuclear fraction. Large macromolecular structures such as Ehproteasome were sedimented at a higher speed. Our knowledge of the molecular machinery involved in the biosynthesis of dolichol-linked oligosaccharide was enriched with the identification of putative genes related to the stepwise assembly of the dolichol-PP-GlcNAc(2)Man(5) core. No evidence of genes supporting further assembly steps was obtained at this time.
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Affiliation(s)
- Milena Salgado
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología (UNAM), Cuernavaca, Morelos, Mexico
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Sánchez R, Saralegui A, Olivos-García A, Scapolla C, Damonte G, Sanchez-Lopez R, Alagón A, Stock RP. Entamoeba histolytica: intracellular distribution of the sec61alpha subunit of the secretory pathway and down-regulation by antisense peptide nucleic acids. Exp Parasitol 2005; 109:241-51. [PMID: 15755422 DOI: 10.1016/j.exppara.2004.12.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Revised: 12/04/2004] [Accepted: 12/10/2004] [Indexed: 11/22/2022]
Abstract
The Sec61alpha protein is defined as a highly conserved essential integral component of the endoplasmic reticulum in eukaryotic cells. We report a detailed immunolocalization of the Entamoeba histolytica homologue of the Sec61alpha subunit (EhSec61alpha), which shows an irregular pattern throughout the cell and is also found on the cell surface, its effective down-regulation by means of antisense peptide nucleic acids and its effects on cell proliferation, subcellular distribution of two virulence factors, and the ability of the trophozoites to cause liver abscess in hamsters. Although Sec61alpha levels are specifically decreased in antisense PNA-treated trophozoites, which proliferate more slowly than the controls, mobilization of the cysteine protease 5 and amoebapore to the cell surface is not significantly impeded and the capacity to induce liver abscess in hamsters is largely unaffected. The implications of these findings are discussed in the context of the peculiar cell biology of E. histolytica.
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Affiliation(s)
- Ricardo Sánchez
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Mexico
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Tamayo EM, Ondarza RN. Characterization of two long vesicle-associated membrane proteins or longins genes from Entamoeba histolytica. Arch Med Res 2004; 35:378-84. [PMID: 15610906 DOI: 10.1016/j.arcmed.2004.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2004] [Accepted: 06/04/2004] [Indexed: 10/26/2022]
Abstract
BACKGROUND This study characterizes two long vesicle-associated membrane protein (VAMP) genes (SYBL-1 and SYBL-2) obtained from DNA of Entamoeba histolytica by PCR amplification. (Nucleotide sequences of the Entamoeba histolytica SYBL-1 and SYBL-2 genes appear in the GeneBank under accession numbers AY256852 and AY309014.) METHODS The two cDNA products include one of 663 bp with sequence of 220 deduced amino acids, and a second of 693 bp with 230 deduced amino acid residues. Both products possess corresponding sequences for longin domain at N-terminus, a soluble N-ethylmaleimide-sensitive factor [NSF] attachment protein receptor (SNARE) coiled-coil region, a transmembrane domain (TM), and an intravesicular tail C-terminal, characteristics of all long VAMPs or longins. The current study identified presence of deduced peptide bonds in SYBL-1 and -2, which indicates that these two long VAMPs from E. histolytica could be appropriate substrates for zinc endopeptidases from tetanus and botulinum neurotoxins with specific activity toward neuronal synaptobrevins. RESULTS Alignment by Basic Local Alignment Search Tool (BLAST) of deduced amino-acid sequence of long VAMPs genes SYBL-1 and -2 showed identity of between 20 and 40% with Caenorhabditis elegans, Dictyostelium discoideum, Drosophila melanogaster, Arabidopsis thaliana, Mus musculus, Homo sapiens, and Plasmodium falciparum. CONCLUSIONS It is possible that these two putative transport proteins are involved in endocytosis/exocytosis during a biological membrane fusion process, which may make them suitable candidates as targets for new drugs. According to published data, this is the first time that two such genes have been isolated from E. histolytica.
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Affiliation(s)
- Elsa María Tamayo
- Centro de Investigación sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Secretaría de Salud (SSA), Cuernavaca, Morelos, Mexico
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Meza I, Clarke M. Dynamics of endocytic traffic ofEntamoeba histolyticarevealed by confocal microscopy and flow cytometry. ACTA ACUST UNITED AC 2004; 59:215-26. [PMID: 15476263 DOI: 10.1002/cm.20038] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Entamoeba histolytica, the protozoan parasite of humans, manifests constitutive endocytosis to obtain nutrients and, when induced to express invasive behavior, as a means of ingesting and processing host cells and tissue debris. E. histolytica trophozoites were grown in liquid axenic medium that contained fluorescently labeled fluid-phase markers, so that the kinetics of uptake, the transit of loaded endosomes through the cytoplasm, and the time of release of the markers could be monitored by flow cytometry. Confocal microscopy of live trophozoites revealed uptake of fluid by avid macropinocytosis and the occurrence of fusion between young and older endosomes, as well as between pinosomes and phagosomes containing bacteria. Endosomes were rapidly acidified, then gradually neutralized; finally, indigestible material was released. Transit of endosomes containing fluid-phase markers required about 2 h. Uptake and release of fluid-phase markers were impaired by drugs that inhibited actin dynamics and actin-myosin interaction; uptake was also impaired by inhibition of PI 3-kinase. A striking feature of the trophozoites was the great heterogeneity of their endocytic behavior.
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Affiliation(s)
- Isaura Meza
- Departamento de Biomedicina Molecular, CINVESTAV del IPN, Mexico DF, Mexico.
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Przyborski JM, Lanzer M. Protein transport and trafficking inPlasmodium falciparum-infected erythrocytes. Parasitology 2004; 130:373-88. [PMID: 15830811 DOI: 10.1017/s0031182004006729] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The human malarial parasitePlasmodium falciparumextensively modifies its host erythrocyte, and to this end, is faced with an interesting challenge. It must not only sort proteins to common organelles such as endoplasmic reticulum, Golgi and mitochondria, but also target proteins across the ‘extracellular’ cytosol of its host cell. Furthermore, as a member of the phylum Apicomplexa, the parasite has to sort proteins to novel organelles such as the apicoplast, micronemes and rhoptries. In order to overcome these difficulties, the parasite has created a novel secretory system, which has been characterized in ever-increasing detail in the past decade. Along with the ‘hardware’ for a secretory system, the parasite also needs to ‘program’ proteins to enable high fidelity sorting to their correct subcellular location. The nature of these sorting signals has remained until relatively recently, enigmatic. Experimental work has now begun to dissect the sorting signals responsible for correct subcellular targeting of parasite-encoded proteins. In this review we summarize the current understanding of such signals, and comment on their role in protein sorting in this organism, which may become a model for the study of novel protein trafficking mechanisms.
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Affiliation(s)
- J M Przyborski
- Hygiene Institute, Department of Parasitology, University of Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
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