scholarly journals Localization of Phosphatidylinositol 4,5-Bisphosphate to Lipid Rafts and Uroids in the Human Protozoan Parasite Entamoeba histolytica

2013 ◽  
Vol 81 (6) ◽  
pp. 2145-2155 ◽  
Author(s):  
Amrita B. Koushik ◽  
Rhonda R. Powell ◽  
Lesly A. Temesvari
Keyword(s):  
Lipid Rafts ◽  
Entamoeba Histolytica ◽  
Protozoan Parasite ◽  
Invasive Infection ◽  
Cellular Functions ◽  
Intestinal Protozoan ◽  
Content Type ◽  
Downstream Effector ◽  
Key Factor ◽  
Actomyosin Cytoskeleton

ABSTRACTEntamoeba histolyticais an intestinal protozoan parasite and is the causative agent of amoebiasis. During invasive infection, highly motile amoebae destroy the colonic epithelium, enter the blood circulation, and disseminate to other organs such as liver, causing liver abscess. Motility is a key factor inE. histolyticapathogenesis, and this process relies on a dynamic actomyosin cytoskeleton. In other systems, phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] is known to regulate a wide variety of cellular functions, including signal transduction, actin remodeling, and cell motility. Little is known about the role of PI(4,5)P2inE. histolyticapathogenicity. In this study, we demonstrate that PI(4,5)P2is localized to cholesterol-rich microdomains, lipid rafts, and the actin-rich fractions of theE. histolyticamembrane. Microscopy revealed that the trailing edge of polarized trophozoites, uroids, are highly enriched in lipid rafts and their constituent lipid, PI(4,5)P2. Polarization and enrichment of uroids and rafts with PI(4,5)P2were enhanced upon treatment ofE. histolyticacells with cholesterol. Exposure to cholesterol also increased intracellular calcium, which is a downstream effector of PI(4,5)P2, with a concomitant increase in motility. Together, our data suggest that inE. histolytica, PI(4,5)P2may signal from lipid rafts and cholesterol may play a role in triggering PI(4,5)P2-mediated signaling to enhance the motility of this pathogen.

scholarly journals Cysteine Protease-Binding Protein Family 6 Mediates the Trafficking of Amylases to Phagosomes in the Enteric Protozoan Entamoeba histolytica

2013 ◽  
Vol 81 (5) ◽  
pp. 1820-1829 ◽  
Author(s):  
Atsushi Furukawa ◽  
Kumiko Nakada-Tsukui ◽  
Tomoyoshi Nozaki
Keyword(s):  
Entamoeba Histolytica ◽  
Cysteine Protease ◽  
Binding Protein ◽  
Proteome Analysis ◽  
Protozoan Parasite ◽  
Cysteine Proteases ◽  
Protein Family ◽  
Intestinal Protozoan ◽  
Α Subunit ◽  
Content Type

ABSTRACTPhagocytosis plays a pivotal role in nutrient acquisition and evasion from the host defense systems inEntamoeba histolytica, the intestinal protozoan parasite that causes amoebiasis. We previously reported thatE. histolyticapossesses a unique class of a hydrolase receptor family, designated the cysteine protease-binding protein family (CPBF), that is involved in trafficking of hydrolases to lysosomes and phagosomes, and we have also reported that CPBF1 and CPBF8 bind to cysteine proteases or β-hexosaminidase α-subunit and lysozymes, respectively. In this study, we showed by immunoprecipitation that CPBF6, one of the most highly expressed CPBF proteins, specifically binds to α-amylase and γ-amylase. We also found that CPBF6 is localized in lysosomes, based on immunofluorescence imaging. Immunoblot and proteome analyses of the isolated phagosomes showed that CPBF6 mediates transport of amylases to phagosomes. We also demonstrated that the carboxyl-terminal cytosolic region of CPBF6 is engaged in the regulation of the trafficking of CPBF6 to phagosomes. Our proteome analysis of phagosomes also revealed new potential phagosomal proteins.

scholarly journals tRNA Gene Sequences Are Required for Transcriptional Silencing in Entamoeba histolytica

2009 ◽  
Vol 9 (2) ◽  
pp. 306-314 ◽  
Author(s):  
Henriette Irmer ◽  
Ina Hennings ◽  
Iris Bruchhaus ◽  
Egbert Tannich
Keyword(s):  
Entamoeba Histolytica ◽  
Trna Gene ◽  
Regulation Of Gene Expression ◽  
Transcriptional Silencing ◽  
Protozoan Parasite ◽  
Upstream Region ◽  
Trna Genes ◽  
Intestinal Protozoan ◽  
Content Type ◽  
Systematic Assessment

ABSTRACT Transcriptional silencing by trans inactivation can contribute to the regulation of gene expression in eukaryotic cells. In the human intestinal protozoan parasite Entamoeba histolytica, trans inactivation of the amoebapore-A gene (AP-A) was recently achieved by episomal transfection of E. histolytica trophozoites with the plasmid psAP1. The mechanism of AP-A trans inactivation is largely unknown, though it was suggested that a partial short interspersed transposable element (SINE) is required. By systematic assessment of various E. histolytica isolates transfected with psAP1 derivates, trans inactivation of AP-A was restricted to the strain HM-1:IMSS (2411) but could not be achieved in other standard laboratory strains. Importantly, sequences of an E. histolytica tRNA array that were located on psAP1 in close proximity to the AP-A upstream region and comprising the glutamic acid (TTC) (E) and tyrosine (GTA) (Y) tRNA genes were indispensable for AP-A silencing. In contrast to the case described in previous reports, SINE was not required for AP-A trans inactivation. AP-A expression could be regained in silenced cells by episomal transfection under the control of a heterologous E. histolytica promoter, opening a way toward future silencing of individual genes of interest in E. histolytica. Our results indicate that tRNA gene-mediated silencing is not restricted to Saccharomyces cerevisiae.

scholarly journals Localization and Targeting of an Unusual Pyridine Nucleotide Transhydrogenase in Entamoeba histolytica

2010 ◽  
Vol 9 (6) ◽  
pp. 926-933 ◽  
Author(s):  
Mohammad Abu Yousuf ◽  
Fumika Mi-ichi ◽  
Kumiko Nakada-Tsukui ◽  
Tomoyoshi Nozaki
Keyword(s):  
Entamoeba Histolytica ◽  
Fluorescent Protein ◽  
Physiological Role ◽  
Protozoan Parasite ◽  
Pyridine Nucleotide ◽  
Immunofluorescence Assay ◽  
Chemical Degradation ◽  
Content Type ◽  
Targeting Signal ◽  
Pyridine Nucleotide Transhydrogenase

ABSTRACT Pyridine nucleotide transhydrogenase (PNT) catalyzes the direct transfer of a hydride-ion equivalent between NAD(H) and NADP(H) in bacteria and the mitochondria of eukaryotes. PNT was previously postulated to be localized to the highly divergent mitochondrion-related organelle, the mitosome, in the anaerobic/microaerophilic protozoan parasite Entamoeba histolytica based on the potential mitochondrion-targeting signal. However, our previous proteomic study of isolated phagosomes suggested that PNT is localized to organelles other than mitosomes. An immunofluorescence assay using anti-E. histolytica PNT (EhPNT) antibody raised against the NADH-binding domain showed a distribution to the membrane of numerous vesicles/vacuoles, including lysosomes and phagosomes. The domain(s) required for the trafficking of PNT to vesicles/vacuoles was examined by using amoeba transformants expressing a series of carboxyl-terminally truncated PNTs fused with green fluorescent protein or a hemagglutinin tag. All truncated PNTs failed to reach vesicles/vacuoles and were retained in the endoplasmic reticulum. These data indicate that the putative targeting signal is not sufficient for the trafficking of PNT to the vesicular/vacuolar compartments and that full-length PNT is necessary for correct transport. PNT displayed a smear of >120 kDa on SDS-PAGE gels. PNGase F and tunicamycin treatment, chemical degradation of carbohydrates, and heat treatment of PNT suggested that the apparent aberrant mobility of PNT is likely attributable to its hydrophobic nature. PNT that is compartmentalized to the acidic compartments is unprecedented in eukaryotes and may possess a unique physiological role in E. histolytica.

scholarly journals Autophagy Activated by Peroxiredoxin of Entamoeba histolytica

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2462
Author(s):  
Xia Li ◽  
Yuhan Zhang ◽  
Yanqing Zhao ◽  
Ke Qiao ◽  
Meng Feng ◽  
...  
Keyword(s):  
Entamoeba Histolytica ◽  
Protozoan Parasite ◽  
Host Cells ◽  
Functional Domain ◽  
Intestinal Protozoan ◽  
Raw264.7 Macrophages ◽  
Evolutionarily Conserved ◽  
Amoebic Colitis ◽  
Dependent Cell ◽  
Cellular Components

Autophagy, an evolutionarily conserved mechanism to remove redundant or dangerous cellular components, plays an important role in innate immunity and defense against pathogens, which, in turn, can regulate autophagy to establish infection within a host. However, for Entamoeba histolytica, an intestinal protozoan parasite causing human amoebic colitis, the interaction with the host cell autophagy mechanism has not been investigated. In this study, we found that E. histolytica peroxiredoxin (Prx), an antioxidant enzyme critical for parasite survival during the invasion of host tissues, could activate autophagy in macrophages. The formation of autophagosomes in macrophages treated with recombinant Prx of E. histolytica for 24 h was revealed by immunofluorescence and immunoblotting in RAW264.7 cells and in mice. Prx was cytotoxic for RAW264.7 macrophages after 48-h treatment, which was partly attributed to autophagy-dependent cell death. RNA interference experiments revealed that Prx induced autophagy mostly through the toll-like receptor 4 (TLR4)–TIR domain-containing adaptor-inducing interferon (TRIF) pathway. The C-terminal part of Prx comprising 100 amino acids was the key functional domain to activate autophagy. These results indicated that Prx of E. histolytica could induce autophagy and cytotoxic effects in macrophages, revealing a new pathogenic mechanism activated by E. histolytica in host cells.

scholarly journals Near-chromosome level genome assembly reveals ploidy diversity and plasticity in the intestinal protozoan parasite Entamoeba histolytica

BMC Genomics ◽  
2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Tetsuro Kawano-Sugaya ◽  
Shinji Izumiyama ◽  
Yasuaki Yanagawa ◽  
Yumiko Saito-Nakano ◽  
Koji Watanabe ◽  
...  
Keyword(s):  
Entamoeba Histolytica ◽  
Evolutionary Biology ◽  
Regulation Of Gene Expression ◽  
Protozoan Parasite ◽  
Model Organisms ◽  
Intestinal Protozoan ◽  
Disease Symptoms ◽  
Veterinary Importance ◽  
Reference Genomes ◽  
Chromosome Level

Abstract Background Amoebozoa is a eukaryotic supergroup composed of unicellular and multicellular amoebic protozoa (e.g. Acanthamoeba, Dictyostelium, and Entamoeba). They are model organisms for studies in cellular and evolutionary biology and are of medical and veterinary importance. Despite their importance, Amoebozoan genome organization and genetic diversity remain poorly studied due to a lack of high-quality reference genomes. The slime mold Dictyostelium discoideum is the only Amoebozoan species whose genome is available at the chromosome-level. Results Here, we provide a near-chromosome-level assembly of the Entamoeba histolytica genome, the second semi-completed Amoebozoan genome. The availability of this improved genome allowed us to discover inter-strain heterogeneity in ploidy at the near-chromosome or sub-chromosome level among 11 clinical isolates and the reference strain. Furthermore, we observed ploidy-independent regulation of gene expression, contrary to what is observed in other organisms, where RNA levels are affected by ploidy. Conclusions Our findings offer new insights into Entamoeba chromosome organization, ploidy, transcriptional regulation, and inter-strain variation, which will help to further decipher observed spectrums of virulence, disease symptoms, and drug sensitivity of E. histolytica isolates.

scholarly journals Knockdown of Five Genes Encoding Uncharacterized Proteins Inhibits Entamoeba histolytica Phagocytosis of Dead Host Cells

2016 ◽  
Vol 84 (4) ◽  
pp. 1045-1053 ◽  
Author(s):  
Adam Sateriale ◽  
Peter Miller ◽  
Christopher D. Huston
Keyword(s):  
Host Cell ◽  
Entamoeba Histolytica ◽  
Protozoan Parasite ◽  
Host Cells ◽  
Data Set ◽  
Feed Forward ◽  
Content Type ◽  
Genes Encoding ◽  
Relative Specificity ◽  
Cell Engulfment

Entamoeba histolyticais the protozoan parasite that causes invasive amebiasis, which is endemic to many developing countries and characterized by dysentery and liver abscesses. The virulence ofE. histolyticacorrelates with the degree of host cell engulfment, or phagocytosis, andE. histolyticaphagocytosis alters amebic gene expression in a feed-forward manner that results in an increased phagocytic ability. Here, we used a streamlined RNA interference screen to silence the expression of 15 genes whose expression was upregulated in phagocyticE. histolyticatrophozoites to determine whether these genes actually function in the phagocytic process. When five of these genes were silenced, amebic strains with significant decreases in the ability to phagocytose apoptotic host cells were produced. Phagocytosis of live host cells, however, was largely unchanged, and the defects were surprisingly specific for phagocytosis. Two of the five encoded proteins, which we namedE. histolyticaILWEQ (EhILWEQ) andE. histolyticaBAR (EhBAR), were chosen for localization via SNAP tag labeling and localized to the site of partially formed phagosomes. Therefore, both EhILWEQ and EhBAR appear to contribute toE. histolyticavirulence through their function in phagocytosis, and the large proportion (5/15 [33%]) of gene-silenced strains with a reduced ability to phagocytose host cells validates the previously published microarray data set demonstrating feed-forward control ofE. histolyticaphagocytosis. Finally, although only limited conclusions can be drawn from studies using the virulence-deficient G3Entamoebastrain, the relative specificity of the defects induced for phagocytosis of apoptotic cells but not healthy cells suggests that cell killing may play a rate-limiting role in the process ofEntamoeba histolyticahost cell engulfment.

scholarly journals Genome-Wide Analysis of Known and Potential Tetraspanins in Entamoeba histolytica

Genes ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 885 ◽  
Author(s):  
Tomii ◽  
Santos ◽  
Nozaki
Keyword(s):  
Entamoeba Histolytica ◽  
Sequence Similarity ◽  
Protozoan Parasite ◽  
Intercellular Signaling ◽  
Intestinal Protozoan ◽  
Membrane Protein Complex ◽  
Genome Wide Analysis ◽  
Protein Complex Formation ◽  
Genome Wide ◽  
Similarity Searches

Tetraspanins are membrane proteins involved in intra- and/or intercellular signaling, and membrane protein complex formation. In some organisms, their role is associated with virulence and pathogenesis. Here, we investigate known and potential tetraspanins in the human intestinal protozoan parasite Entamoeba histolytica. We conducted sequence similarity searches against the proteome data of E. histolytica and newly identified nine uncharacterized proteins as potential tetraspanins in E. histolytica. We found three subgroups within known and potential tetraspanins, as well as subgroup-associated features in both their amino acid and nucleotide sequences. We also examined the subcellular localization of a few representative tetraspanins that might be potentially related to pathogenicity. The results in this study could be useful resources for further understanding and downstream analyses of tetraspanins in Entamoeba.

scholarly journals The Intestinal Protozoan Parasite Entamoeba histolytica Contains 20 Cysteine Protease Genes, of Which Only a Small Subset Is Expressed during In Vitro Cultivation

2003 ◽  
Vol 2 (3) ◽  
pp. 501-509 ◽  
Author(s):  
Iris Bruchhaus ◽  
Brendan J. Loftus ◽  
Neil Hall ◽  
Egbert Tannich
Keyword(s):  
Entamoeba Histolytica ◽  
Cysteine Protease ◽  
Cathepsin L ◽  
Protozoan Parasite ◽  
Cysteine Proteases ◽  
Small Subset ◽  
In Vitro Cultivation ◽  
Intestinal Protozoan ◽  
Parasite Life Cycle

ABSTRACT Cysteine proteases are known to be important pathogenicity factors of the protozoan parasite Entamoeba histolytica. So far, a total of eight genes coding for cysteine proteases have been identified in E. histolytica, two of which are absent in the closely related nonpathogenic species E. dispar. However, present knowledge is restricted to enzymes expressed during in vitro cultivation of the parasite, which might represent only a subset of the entire repertoire. Taking advantage of the current E. histolytica genome-sequencing efforts, we analyzed databases containing more than 99% of all ameba gene sequences for the presence of cysteine protease genes. A total of 20 full-length genes was identified (including all eight genes previously reported), which show 10 to 86% sequence identity. The various genes obviously originated from two separate ancestors since they form two distinct clades. Despite cathepsin B-like substrate specificities, all of the ameba polypeptides are structurally related to cathepsin L-like enzymes. None of the previously described enzymes but 7 of the 12 newly identified proteins are unique compared to cathepsins of higher eukaryotes in that they are predicted to have transmembrane or glycosylphosphatidylinositol anchor attachment domains. Southern blot analysis revealed that orthologous sequences for all of the newly identified proteases are present in E. dispar. Interestingly, the majority of the various cysteine protease genes are not expressed in E. histolytica or E. dispar trophozoites during in vitro cultivation. Therefore, it is likely that at least some of these enzymes are required for infection of the human host and/or for completion of the parasite life cycle.

scholarly journals Mass Spectrometric Analysis of l-Cysteine Metabolism: Physiological Role and Fate of l-Cysteine in the Enteric Protozoan Parasite Entamoeba histolytica

mBio ◽  
2014 ◽  
Vol 5 (6) ◽  
Author(s):  
Ghulam Jeelani ◽  
Dan Sato ◽  
Tomoyoshi Soga ◽  
Haruo Watanabe ◽  
Tomoyoshi Nozaki
Keyword(s):  
Oxidative Stress ◽  
Amino Acid ◽  
Carboxylic Acid ◽  
Stable Isotope ◽  
Carboxylic Acids ◽  
Entamoeba Histolytica ◽  
Protozoan Parasite ◽  
Protozoan Parasites ◽  
Metabolic Fate ◽  
Content Type

ABSTRACTl-Cysteine is essential for virtually all living organisms, from bacteria to higher eukaryotes. Besides having a role in the synthesis of virtually all proteins and of taurine, cysteamine, glutathione, and other redox-regulating proteins,l-cysteine has important functions under anaerobic/microaerophilic conditions. In anaerobic or microaerophilic protozoan parasites, such asEntamoeba histolytica,l-cysteine has been implicated in growth, attachment, survival, and protection from oxidative stress. However, a specific role of this amino acid or related metabolic intermediates is not well understood. In this study, using stable-isotope-labeledl-cysteine and capillary electrophoresis-time of flight mass spectrometry, we investigated the metabolism ofl-cysteine inE. histolytica. [U-13C3,15N]l-cysteine was rapidly metabolized into three unknown metabolites, besidesl-cystine andl-alanine. These metabolites were identified as thiazolidine-4-carboxylic acid (T4C), 2-methyl thiazolidine-4-carboxylic acid (MT4C), and 2-ethyl-thiazolidine-4-carboxylic acid (ET4C), the condensation products ofl-cysteine with aldehydes. We demonstrated that these 2-(R)-thiazolidine-4-carboxylic acids serve for storage ofl-cysteine. Liberation ofl-cysteine occurred when T4C was incubated with amebic lysates, suggesting enzymatic degradation of thesel-cysteine derivatives. Furthermore, T4C and MT4C significantly enhanced trophozoite growth and reduced intracellular reactive oxygen species (ROS) levels when it was added to cultures, suggesting that 2-(R)-thiazolidine-4-carboxylic acids are involved in the defense against oxidative stress.IMPORTANCEAmebiasis is a human parasitic disease caused by the protozoan parasiteEntamoeba histolytica. In this parasite,l-cysteine is the principal low-molecular-weight thiol and is assumed to play a significant role in supplying the amino acid during trophozoite invasion, particularly when the parasites move from the anaerobic intestinal lumen to highly oxygenated tissues in the intestine and the liver. It is well known thatE. histolyticaneeds a comparatively high concentration ofl-cysteine for its axenic cultivation. However, the reason for and the metabolic fate ofl-cysteine in this parasite are not well understood. Here, using a metabolomic and stable-isotope-labeled approach, we investigated the metabolic fate of this amino acid in these parasites. We found thatl-cysteine inside the cell rapidly reacts with aldehydes to form 2-(R)-thiazolidine-4-carboxylic acid. We showed that these 2-(R)-thiazolidine-4-carboxylic derivatives serve as anl-cysteine source, promote growth, and protect cells against oxidative stress by scavenging aldehydes and reducing the ROS level. Our findings represent the first demonstration of 2-(R)-thiazolidine-4-carboxylic acids and their roles in protozoan parasites.

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