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CynthiaVanegas-Villa S, Milena Torres-Cifuentes D, Baylon-Pacheco L, Espíritu-Gordillo P, Durán-Díaz Á, Luis Rosales-Encina J, Omaña-Molina M. External pH Variations Modify Proliferation, Erythrophagocytosis, Cytoskeleton Remodeling, and Cell Morphology of Entamoeba histolytica Trophozoites. Protist 2022; 173:125857. [DOI: 10.1016/j.protis.2022.125857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 01/14/2022] [Accepted: 01/17/2022] [Indexed: 10/19/2022]
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Low molecular weight protein tyrosine phosphatase (LMW-PTP2) protein can potentially modulate virulence of the parasite Entamoeba histolytica. Mol Biochem Parasitol 2021; 242:111360. [PMID: 33428948 DOI: 10.1016/j.molbiopara.2021.111360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 12/22/2020] [Accepted: 01/05/2021] [Indexed: 02/06/2023]
Abstract
The Entamoeba histolytica parasite is the causative agent of amebiasis, infecting approximately 1% of the world population and causing 100,000 deaths per year. It binds to Fibronectin (FN), activating signaling pathways regulated by kinases and phosphatases. EhLMW-PTPs genes from E. histolytica encode for Low Molecular Weight Tyrosine Phosphatases expressed in trophozoites and amoebic cysts. The role of these phosphatases in the virulence of the parasite has not yet been well characterized. Our results showed a differential expression of the EhLMW-PTPs, at the mRNA and protein levels, in an asynchronous trophozoites culture. Furthermore, we observed that trophozoites transfected that overexpressed EhLMW-PTP2 phagocytized fewer erythrocytes, possibly due to decreased phagocytic cups, and showed deficiencies in adherence to FN and less cytopathic effect. These analyzes suggest that the parasite's EhLMW-PTPs have an essential role in the mechanisms of proliferation, adhesion, and phagocytosis, regulating its pathogenicity.
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Agarwal S, Rath PP, Anand G, Gourinath S. Uncovering the Cyclic AMP Signaling Pathway of the Protozoan Parasite Entamoeba histolytica and Understanding Its Role in Phagocytosis. Front Cell Infect Microbiol 2020; 10:566726. [PMID: 33102254 PMCID: PMC7546249 DOI: 10.3389/fcimb.2020.566726] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 08/17/2020] [Indexed: 01/13/2023] Open
Abstract
Second messenger signaling controls a surprisingly diverse range of processes in several eukaryotic pathogens. Molecular machinery and pathways involving these messengers thus hold tremendous opportunities for therapeutic interventions. Relative to Ca2+ signaling, the knowledge of a crucial second messenger cyclic AMP (cAMP) and its signaling pathway is very scant in the intestinal parasite Entamoeba histolytica. In the current study, mining the available genomic resources, we have for the first time identified the cAMP signal transduction pathway of E. histolytica. Three heptahelical proteins with variable G-protein-coupled receptor domains, heterotrimeric G-proteins (Gα, Gβ, and Gγ subunits), soluble adenylyl cyclase, cyclase-associated protein, and enzyme carbonic anhydrase were identified in its genome. We could also identify several putative candidate genes for cAMP downstream effectors such as protein kinase A, A-kinase anchoring proteins, and exchange protein directly activated by the cAMP pathway. Using specific inhibitors against key identified targets, we could observe changes in the intracellular cAMP levels as well as defect in the rate of phagocytosis of red blood cells by the parasite E. histolytica. We thus strongly believe that characterization of some of these unexplored crucial signaling determinants will provide a paradigm shift in understanding the pathogenicity of this organism.
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Affiliation(s)
- Shalini Agarwal
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | | | - Gaurav Anand
- International Center for Genetic Engineering and Biotechnology, New Delhi, India
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Calcium modulates the domain flexibility and function of an α-actinin similar to the ancestral α-actinin. Proc Natl Acad Sci U S A 2020; 117:22101-22112. [PMID: 32848067 DOI: 10.1073/pnas.1917269117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The actin cytoskeleton, a dynamic network of actin filaments and associated F-actin-binding proteins, is fundamentally important in eukaryotes. α-Actinins are major F-actin bundlers that are inhibited by Ca2+ in nonmuscle cells. Here we report the mechanism of Ca2+-mediated regulation of Entamoeba histolytica α-actinin-2 (EhActn2) with features expected for the common ancestor of Entamoeba and higher eukaryotic α-actinins. Crystal structures of Ca2+-free and Ca2+-bound EhActn2 reveal a calmodulin-like domain (CaMD) uniquely inserted within the rod domain. Integrative studies reveal an exceptionally high affinity of the EhActn2 CaMD for Ca2+, binding of which can only be regulated in the presence of physiological concentrations of Mg2+ Ca2+ binding triggers an increase in protein multidomain rigidity, reducing conformational flexibility of F-actin-binding domains via interdomain cross-talk and consequently inhibiting F-actin bundling. In vivo studies uncover that EhActn2 plays an important role in phagocytic cup formation and might constitute a new drug target for amoebic dysentery.
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Immunotoxicity in Ascidians: Antifouling Compounds Alternative to Organotins—V. the Case of Dichlofluanid. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2020. [DOI: 10.3390/jmse8060396] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Dichlofluanid has long been employed as a fungicide in agriculture and has been massively introduced in antifouling paints for boat hulls over the last two decades. One of the most important toxic effects of antifoulants is represented by immunosuppression in marine invertebrates, which can be analysed in vitro with a number of short-term toxicity assays on haemocytes. Among bioindicators, the colonial ascidian Botryllus schlosseri is a useful candidate; it is a filter-feeding organism living in the water-sediment interface that is found worldwide and is sensitive to antifouling xenobiotics. Dichlofluanid adversely affects both immunocyte lines (phagocyte and cytotoxic lines) after exposure to sublethal concentrations. At 0.05 μM (16.65 μg/L), dichlofluanid induced haemocyte apoptosis and cell shrinkage with a decrease in both motility and phagocytosis. At the lowest concentration (0.01 μM, 3.33 μg/L), inhibition of pivotal enzymatic activities of phagocytes and cytotoxic cells occurred. At the highest concentration (0.1 μM, 33.3 μg/L), dichlofluanid increased glutathione oxidation, leading to stress conditions. The effects of dichlofluanid on immune defence responses are similar to those of organometal-based antifoulants (i.e., organotin compounds and zinc pyrithione), and its use in coastal areas requires attention.
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Talamás-Lara D, Rosales-Encina JL, Chávez-Munguía B, Acosta-Virgen K, Hernández-Ramírez VI, Salazar-Villatoro L, Espinosa-Cantellano M, Martínez-Palomo A, Talamás-Rohana P. Entamoeba histolytica and Entamoeba dispar: Morphological and Behavioral Differences Induced by Fibronectin through GTPases Activation and Actin-Binding Proteins. J Eukaryot Microbiol 2020; 67:491-504. [PMID: 32302033 DOI: 10.1111/jeu.12797] [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: 12/16/2019] [Revised: 02/19/2020] [Accepted: 03/26/2020] [Indexed: 01/09/2023]
Abstract
Early steps of tissue invasion by Entamoeba histolytica are mediated by adhesion and migration through matrix components such as fibronectin with the participation of the actin cytoskeleton. Striking differences in their produced structures, movement, and migration were found. These observations suggest differential changes in their ability to organize the actin cytoskeleton and, therefore, to modify its morphology after adhesion to fibronectin. To understand these observations, we explore deeper the cytoskeleton pathway of E. histolytica compared to Entamoeba dispar, analyzing the activation and involvement of actin cytoskeleton regulatory proteins such as small GTPases (Rho, Rac1 and Cdc42), myosin IB, paxillin, alpha-actinin, and ARP2/3 during interaction with fibronectin. Results showed a higher activation of Rac1 in E. histolytica compared to E. dispar, while Cdc42 and RhoA were equally activated in both amebae; besides, variations in the amount of myosin IB, paxillin, and ARP2/3 were detected among these species, coinciding and reflected in formation of lamellipodia in E. histolytica and filopodia in E. dispar. These could partially explain the higher invasive capacity of E. histolytica compared to E. dispar, due to its pleomorphic ability, high motility, migration, activation, and abundance of proteins involved in the cytoskeleton arrangement.
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Affiliation(s)
- Daniel Talamás-Lara
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal, 07360, Mexico City, Mexico
| | - José Luis Rosales-Encina
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal, 07360, Mexico City, Mexico
| | - Bibiana Chávez-Munguía
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal, 07360, Mexico City, Mexico
| | - Karla Acosta-Virgen
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal, 07360, Mexico City, Mexico
| | - Verónica Ivonne Hernández-Ramírez
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal, 07360, Mexico City, Mexico
| | - Lizbeth Salazar-Villatoro
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal, 07360, Mexico City, Mexico
| | - Martha Espinosa-Cantellano
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal, 07360, Mexico City, Mexico
| | - Adolfo Martínez-Palomo
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal, 07360, Mexico City, Mexico
| | - Patricia Talamás-Rohana
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal, 07360, Mexico City, Mexico
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Gutiérrez-Sánchez M, Carrasco-Yepez MM, Herrera-Díaz J, Rojas-Hernández S. Identification of differential protein recognition pattern between Naegleria fowleri and Naegleria lovaniensis. Parasite Immunol 2020; 42:e12715. [PMID: 32191816 DOI: 10.1111/pim.12715] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 03/05/2020] [Accepted: 03/13/2020] [Indexed: 12/15/2022]
Abstract
Many pathogenicity factors are involved in the development of primary amoebic meningoencephalitis (PAM) caused by N fowleri. However, most of them are not exclusive for N fowleri and they have not even been described in other nonpathogenic Naegleria species. Therefore, the objective of this work was to identify differential proteins and protein pattern recognition between Naegleria fowleri and Naegleria lovaniensis using antibodies anti-N fowleri as strategy to find vaccine candidates against meningoencephalitis. Electrophoresis and Western blots conventional and 2-DE were performed for the identification of antigenic proteins, and these were analysed by the mass spectrometry technique. The results obtained in 2-DE gels and Western blot showed very notable differences in spot intensity between these two species, specifically those with relative molecular weight of 100, 75, 50 and 19 kDa. Some spots corresponding to these molecular weights were identified as actin fragment, myosin II, heat shock protein, membrane protein Mp2CL5 among others, with differences in theoretical post-translational modifications. In this work, we found differences in antigenic proteins between both species, proteins that could be used for a further development of vaccines against N fowleri infection.
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Affiliation(s)
- Mara Gutiérrez-Sánchez
- Laboratorio de Inmunobiología Molecular y Celular, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, México City, Mexico
| | - Maria Maricela Carrasco-Yepez
- Laboratorio de Microbiología, Grupo CyMA, Unidad de Investigación Interdisciplinaria en Ciencias de la Salud y la Educación, Universidad Nacional Autónoma de México, UNAM FES Iztacala, Tlalnepantla, Mexico
| | - Jorge Herrera-Díaz
- Unidad de Servicios de Apoyo a la Investigación y la Industria, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Saul Rojas-Hernández
- Laboratorio de Inmunobiología Molecular y Celular, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, México City, Mexico
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Agarwal S, Anand G, Sharma S, Parimita Rath P, Gourinath S, Bhattacharya A. EhP3, a homolog of 14-3-3 family of protein participates in actin reorganization and phagocytosis in Entamoeba histolytica. PLoS Pathog 2019; 15:e1007789. [PMID: 31095644 PMCID: PMC6541287 DOI: 10.1371/journal.ppat.1007789] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 05/29/2019] [Accepted: 04/24/2019] [Indexed: 11/19/2022] Open
Abstract
The highly conserved proteins of the 14-3-3 family are universal adaptors known to regulate an enormous range of cellular processes in eukaryotes. However, their biological functions remain largely uncharacterized in pathogenic protists comprising of several 14-3-3 protein isoforms. In this study, we report the role of 14-3-3 in coordinating cytoskeletal dynamics during phagocytosis in a professional phagocytic protist Entamoeba histolytica, the etiological agent of human amebiasis. There are three isoforms of 14-3-3 protein in amoeba and here we have investigated Eh14-3-3 Protein 3 (EhP3). Live and fixed cell imaging studies revealed the presence of this protein throughout the parasite phagocytosis process, with high rate of accumulation at the phagocytic cups and closed phagosomes. Conditional suppression of EhP3 expression caused significant defects in phagocytosis accompanied by extensive diminution of F-actin at the site of cup formation. Downregulated cells also exhibited defective recruitment of an F-actin stabilizing protein, EhCoactosin at the phagocytic cups. In addition, mass spectrometry based analysis further revealed a large group of EhP3-associated proteins, many of these proteins are known to regulate cytoskeletal architecture in E histolytica. The dynamics of these proteins may also be controlled by EhP3. Taken together, our findings strongly suggest that EhP3 is a novel and a key regulatory element of actin dynamics and phagocytosis in E. histolytica. Phagocytosis of host cells is central to pathogenesis of protist parasite Entamoeba histolytica, the etiological agent of human amebiasis. It is a complex and multistep process that requires dynamic remodelling of the actin cytoskeleton by a large number of scaffolding, signaling and actin-binding proteins (ABPs). Although several parasite ligands such as EhC2PK, EhCaBP1, EhCaBP3, EhAK1, Arp2/3 complex and EhCoactosin that participate in the phagocytic machinery have been identified, the mechanistic insights to their regulation process remain largely elusive. We have in this study identified and characterized the important role of scaffolding protein EhP3 in modulating cytoskeletal dynamics and regulating phagocytosis in E. histolytica. Expression knockdown, imaging and interaction studies suggest that EhP3 function as an adaptor molecule that controls the localization of an F-actin stabilizing protein EhCoactosin and thus the dynamics of F-actin rearrangement during phagocytosis. EhP3 also interact with other actin dynamics regulating proteins that may in coordination regulate cytoskeletal dynamics and thereby phagocytosis in Entamoeba.
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Affiliation(s)
- Shalini Agarwal
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
- * E-mail:
| | - Gaurav Anand
- International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Shalini Sharma
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | | | | | - Alok Bhattacharya
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
- Ashoka University, P.O. Rai, Sonepat, Haryana, India
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Mueller C, Graindorge A, Soldati-Favre D. Functions of myosin motors tailored for parasitism. Curr Opin Microbiol 2017; 40:113-122. [DOI: 10.1016/j.mib.2017.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Revised: 11/02/2017] [Accepted: 11/02/2017] [Indexed: 01/01/2023]
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Deloer S, Nakamura R, Mi-Ichi F, Adachi K, Kobayashi S, Hamano S. Mouse models of amoebiasis and culture methods of amoeba. Parasitol Int 2016; 65:520-525. [PMID: 27080249 DOI: 10.1016/j.parint.2016.03.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 03/17/2016] [Accepted: 03/29/2016] [Indexed: 10/21/2022]
Abstract
Entamoeba histolytica is the third leading parasitic cause of man mortality in the world. Infection occurs via ingestion of food or water contaminated with cysts of E. histolytica. Amoebae primarily colonize the intestine. The majority of amoebic infections are asymptomatic, but under some conditions, approximately 4-10% of infections progress to the invasive form of the disease. To better understand the pathogenesis of amoebiasis and the interaction between amoebae and their hosts, the development of suitable animal models is crucial. Pigs, gerbils, cats and mice are used as animal models for the study of amoebiasis in the laboratory. Among these, the most commonly used model is the mouse. In addition to intestinal amoebiasis, we developed a mouse model of liver abscess by inoculating amoeba through portal vein. However, the frequency of successful infection remains low, which is dependent on the conditions of amoebae in the laboratory. As the maintenance of virulent amoebae in the laboratory is unstable, it needs further refinement. This review summarizes mouse models of amoebiasis and the current state of laboratory culture method of amoebae.
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Affiliation(s)
- Sharmina Deloer
- Department of Parasitology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Doctoral Leadership Program, Graduate School of Biomedical Science, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Risa Nakamura
- Department of Parasitology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Doctoral Leadership Program, Graduate School of Biomedical Science, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Fumika Mi-Ichi
- Divisions of Molecular and Cellular Immunoscience, Department of Biomolecular Sciences, Faculty of Medicine, Saga University, Saga 849-8501, Japan
| | - Keishi Adachi
- Department of Immunology, Yamaguchi University Graduate School of Medicine, Ube 755-8505, Japan
| | - Seiki Kobayashi
- Graduate School of Medicine, Department of Infectious Diseases, Keio University School of Medicine, Tokyo 160-8582, Japan
| | - Shinjiro Hamano
- Department of Parasitology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Doctoral Leadership Program, Graduate School of Biomedical Science, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
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Singh M, Sharma S, Bhattacharya A, Tatu U. Heat Shock Protein 90 regulates encystation in Entamoeba. Front Microbiol 2015; 6:1125. [PMID: 26528271 PMCID: PMC4602144 DOI: 10.3389/fmicb.2015.01125] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 09/28/2015] [Indexed: 11/18/2022] Open
Abstract
Enteric protozoan Entamoeba histolytica is a major cause of debilitating diarrheal infection worldwide with high morbidity and mortality. Even though the clinical burden of this parasite is very high, this infection is categorized as a neglected disease. Parasite is transmitted through feco-oral route and exhibit two distinct stages namely – trophozoites and cysts. Mechanism and regulation of encystation is not clearly understood. Previous studies have established the role of Heat shock protein 90 (Hsp90) in regulating stage transition in various protozoan parasites like Giardia, Plasmodium, Leishmania, and Toxoplasma. Our study for the first time reports that Hsp90 plays a crucial role in life cycle of Entamoeba as well. We identify Hsp90 to be a negative regulator of encystation in Entamoeba. We also show that Hsp90 inhibition interferes with the process of phagocytosis in Entamoeba. Overall, we show that Hsp90 plays an important role in virulence and transmission of Entamoeba.
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Affiliation(s)
- Meetali Singh
- Department of Biochemistry, Indian Institute of Science Bangalore, India
| | - Shalini Sharma
- School of Life Sciences, Jawaharlal Nehru University New Delhi, India
| | - Alok Bhattacharya
- School of Life Sciences, Jawaharlal Nehru University New Delhi, India
| | - Utpal Tatu
- Department of Biochemistry, Indian Institute of Science Bangalore, India
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Unconventional actins and actin-binding proteins in human protozoan parasites. Int J Parasitol 2015; 45:435-47. [DOI: 10.1016/j.ijpara.2015.01.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 12/19/2014] [Accepted: 01/27/2015] [Indexed: 12/11/2022]
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Zysset-Burri DC, Müller N, Beuret C, Heller M, Schürch N, Gottstein B, Wittwer M. Genome-wide identification of pathogenicity factors of the free-living amoeba Naegleria fowleri. BMC Genomics 2014; 15:496. [PMID: 24950717 PMCID: PMC4082629 DOI: 10.1186/1471-2164-15-496] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 06/11/2014] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND The free-living amoeba Naegleria fowleri is the causative agent of the rapidly progressing and typically fatal primary amoebic meningoencephalitis (PAM) in humans. Despite the devastating nature of this disease, which results in > 97% mortality, knowledge of the pathogenic mechanisms of the amoeba is incomplete. This work presents a comparative proteomic approach based on an experimental model in which the pathogenic potential of N. fowleri trophozoites is influenced by the compositions of different media. RESULTS As a scaffold for proteomic analysis, we sequenced the genome and transcriptome of N. fowleri. Since the sequence similarity of the recently published genome of Naegleria gruberi was far lower than the close taxonomic relationship of these species would suggest, a de novo sequencing approach was chosen. After excluding cell regulatory mechanisms originating from different media compositions, we identified 22 proteins with a potential role in the pathogenesis of PAM. Functional annotation of these proteins revealed, that the membrane is the major location where the amoeba exerts its pathogenic potential, possibly involving actin-dependent processes such as intracellular trafficking via vesicles. CONCLUSION This study describes for the first time the 30 Mb-genome and the transcriptome sequence of N. fowleri and provides the basis for the further definition of effective intervention strategies against the rare but highly fatal form of amoebic meningoencephalitis.
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Affiliation(s)
| | | | | | | | | | | | - Matthias Wittwer
- Biology Division, Spiez Laboratory, Federal Office for Civil Protection, Austrasse, CH-3700 Spiez, Switzerland.
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Proteomic profiling reveals that EhPC4 transcription factor induces cell migration through up-regulation of the 16-kDa actin-binding protein EhABP16 in Entamoeba histolytica. J Proteomics 2014; 111:46-58. [PMID: 24721673 DOI: 10.1016/j.jprot.2014.03.041] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 03/24/2014] [Accepted: 03/28/2014] [Indexed: 11/20/2022]
Abstract
UNLABELLED Actin cytoskeleton is an essential structure involved in cell migration and invasion in parasites. In Entamoeba histolytica, the protozoan parasite causing human amoebiasis, the mechanisms underlying the expression of migration-related genes are poorly understood. Here, we investigated the biological effects of ectopic overexpression of EhPC4 (positive coactivator 4) in cell migration of E. histolytica trophozoites. Using differential in gel two-dimensional electrophoresis, 33 modulated proteins were detected in EhPC4-overexpressing cells. By electrospray ionization tandem mass spectrometry (ESI-MS/MS) analysis, 16 of these proteins were identified. Interestingly, four up-regulated proteins involved in cytoskeleton organization and cell migration were identified. Particularly, we found the up-regulation of a 16-kDa actin-binding protein (EhABP16) which is a putative member of the cofilin/tropomyosin family involved in actin polymerization. EhPC4 overexpression induced a significant increase in migration of trophozoites and in the destruction of human SW480 colon cells. Consistently, silencing of gene expression by RNA interference of EhABP16 significantly impairs cell migration. These changes were associated to alterations in the organization of actin cytoskeleton, and suppression of uropod-like structure formation in EhABP16-deficient cells. In summary, we have uncovered novel proteins modulated by EhPC4, including EhABP16, with a potential role in cell migration, cytopathogenicity and virulence in E. histolytica. BIOLOGICAL SIGNIFICANCE The human pathogen Entamoeba histolytica infects around 50million people worldwide resulting in 40,000-100,000 deaths annually. Cell motility is a complex trait that is critical for parasites adaptation, spread and invasion processes into host tissues; it has been associated with virulence. In this study, we used a differential proteomic approach to demonstrate that E. histolytica EhPC4 induces changes in the expression of actin cytoskeleton proteins, including EhABP16, promoting a significant increase in cell motility and destruction of intestinal human cells. Particularly, we demonstrated for the first time that abrogation of EhABP16 impairs cell migration by altering the actin cytoskeleton dynamics and uropod-like structure formation in trophozoites. These data contribute to the understanding of molecular mechanisms that regulate virulence properties in this neglected protozoan parasite.
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Abstract
The parasite Entamoeba histolytica causes amebic colitis and systemic amebiasis. Among the known amebic factors contributing to pathogenesis are signaling pathways involving heterotrimeric and Ras superfamily G proteins. Here, we review the current knowledge of the roles of heterotrimeric G protein subunits, Ras, Rho and Rab GTPase families in E. histolytica pathogenesis, as well as of their downstream signaling effectors and nucleotide cycle regulators. Heterotrimeric G protein signaling likely modulates amebic motility and attachment to and killing of host cells, in part through activation of an RGS-RhoGEF (regulator of G protein signaling-Rho guanine nucleotide exchange factor) effector. Rho family GTPases, as well as RhoGEFs and Rho effectors (formins and p21-activated kinases) regulate the dynamic actin cytoskeleton of E. histolytica and associated pathogenesis-related cellular processes, such as migration, invasion, phagocytosis and evasion of the host immune response by surface receptor capping. A remarkably large family of 91 Rab GTPases has multiple roles in a complex amebic vesicular trafficking system required for phagocytosis and pinocytosis and secretion of known virulence factors, such as amebapores and cysteine proteases. Although much remains to be discovered, recent studies of G protein signaling in E. histolytica have enhanced our understanding of parasitic pathogenesis and have also highlighted possible targets for pharmacological manipulation.
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The Calmodulin-like calcium binding protein EhCaBP3 of Entamoeba histolytica regulates phagocytosis and is involved in actin dynamics. PLoS Pathog 2012; 8:e1003055. [PMID: 23300437 PMCID: PMC3531509 DOI: 10.1371/journal.ppat.1003055] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Accepted: 10/11/2012] [Indexed: 11/20/2022] Open
Abstract
Phagocytosis is required for proliferation and pathogenesis of Entamoeba histolytica and erythrophagocytosis is considered to be a marker of invasive amoebiasis. Ca2+ has been found to play a central role in the process of phagocytosis. However, the molecular mechanisms and the signalling mediated by Ca2+ still remain largely unknown. Here we show that Calmodulin-like calcium binding protein EhCaBP3 of E. histolytica is directly involved in disease pathomechanism by its capacity to participate in cytoskeleton dynamics and scission machinery during erythrophagocytosis. Using imaging techniques EhCaBP3 was found in phagocytic cups and newly formed phagosomes along with actin and myosin IB. In vitro studies confirmed that EhCaBP3 directly binds actin, and affected both its polymerization and bundling activity. Moreover, it also binds myosin 1B in the presence of Ca2+. In cells where EhCaBP3 expression was down regulated by antisense RNA, the level of RBC uptake was reduced, myosin IB was found to be absent at the site of pseudopod cup closure and the time taken for phagocytosis increased, suggesting that EhCaBP3 along with myosin 1B mediate the closure of phagocytic cups. Experiments with EhCaBP3 mutant defective in Ca2+ -binding showed that Ca2+ binding is required for phagosome formation. Liposome binding assay revealed that EhCaBP3 recruitment and enrichment to membrane is independent of any cellular protein as it binds directly to phosphatidylserine. Taken together, our results suggest a novel pathway mediating phagocytosis in E. histolytica, and an unusual mechanism of modulation of cytoskeleton dynamics by two calcium binding proteins, EhCaBP1 and EhCaBP3 with mostly non-overlapping functions. Entamoeba histolytica is one of the major causes of morbidity and mortality in developing countries. Phagocytosis plays an important role in both survival and virulence and has been used as a virulence marker. Inhibition of phagocytosis leads to a defect in cellular proliferation. Therefore, the molecules that participate in phagocytosis are good targets for developing new drugs. However, the molecular mechanism of the process is still largely unknown. Here, we demonstrate that Calmodulin-like calcium binding protein EhCaBP3 is involved in erythrophagocytosis. We show this by a number of different approaches including immunostaining of actin, myosin1B, EhCaBP1 and EhCaBP3 during uptake of RBC; over expression and down regulation of EhCaBP3, and over expression of calcium defective mutant of EhCaBP3. Our analysis suggests that EhCaBP3 can regulate actin dynamics. Along with actin and myosin 1B it can participate in both initiation and formation of phagosomes. The Ca2+-bound form of this protein is required only for progression from cups into early phagosomes but not for initiation. Our results demonstrate the complex role of Ca2+ binding proteins, EhCaBP1 and EhCaBP3 in regulation of phagocytosis in the protist parasite E. histolytica and the novel mechanisms of manipulating actin dynamics at multiple levels.
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Bosch DE, Yang B, Siderovski DP. Entamoeba histolytica Rho1 regulates actin polymerization through a divergent, diaphanous-related formin. Biochemistry 2012; 51:8791-801. [PMID: 23050667 PMCID: PMC3491106 DOI: 10.1021/bi300954g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Entamoeba histolytica requires a dynamic actin cytoskeleton for intestinal and systemic pathogenicity. Diaphanous-related formins represent an important family of actin regulators that are activated by Rho GTPases. The E. histolytica genome encodes a large family of Rho GTPases and three diaphanous-related formins, of which EhFormin1 is known to regulate mitosis and cytokinesis in trophozoites. We demonstrate that EhFormin1 modulates actin polymerization through its formin homology 2 domain. Despite a highly divergent diaphanous autoinhibitory domain, EhFormin1 is autoinhibited by an N- and C-terminal intramolecular interaction but activated upon binding of EhRho1 to the N-terminal domain tandem. A crystal structure of the EhRho1·GTPγS-EhFormin1 complex illustrates an EhFormin1 conformation that diverges from mammalian mDia1 and lacks a secondary interaction with a Rho insert helix. The structural model also highlights residues required for specific recognition of the EhRho1 GTPase and suggests that the molecular mechanisms of EhFormin1 autoinhibition and activation differ from those of mammalian homologues.
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Affiliation(s)
- Dustin E. Bosch
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7365 USA
| | - Bing Yang
- Department of Cell and Developmental Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7365 USA
| | - David P. Siderovski
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, WV 26506-9229 USA,Address correspondence to Dr. David P. Siderovski, 3051 Robert C. Byrd Health Sciences Center, West Virginia University School of Medicine, Morgantown, WV 26506-9229 USA. Tel: 304-293-4991;
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Rastew E, Vicente JB, Singh U. Oxidative stress resistance genes contribute to the pathogenic potential of the anaerobic protozoan parasite, Entamoeba histolytica. Int J Parasitol 2012; 42:1007-15. [PMID: 23009748 DOI: 10.1016/j.ijpara.2012.08.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 08/21/2012] [Accepted: 08/27/2012] [Indexed: 01/06/2023]
Abstract
The protozoan parasite, Entamoeba histolytica, invades the host colon causing significant tissue destruction and inflammation. Upon host infection, the parasite is confronted with reactive oxygen and nitrogen species (ROS/RNS) that cause large-scale changes in gene expression profiles, which likely support the parasite's adaptation to the host environment. We have previously identified oxidative and nitrosative stress responsive genes using whole-genome expression profiling. Functional studies on two such genes are now reported and demonstrate that they have roles in parasite virulence. EHI_056680 encodes a small hypothetical protein named E. histolytica stress-induced adhesion factor (EhSIAF); EHI_188210 encodes a putative phospholipid transporting P-type ATPase/flippase (EhPTPA). Over-expression of each protein in E. histolytica trophozoites enhanced parasite survival in response to oxidative stress. Exposure to oxidative and nitrosative stress did not affect the localization of EhSIAF or EhPTPA but markedly increased EhPTPA protein levels. Interestingly, over-expression of each gene resulted in parasites with increased adherence to healthy mammalian cells, but increased adherence to apoptotic cells was noted only in EhSIAF over-expressing parasites. However, despite having increased adherence to both healthy and apoptotic host cells, EhSIAF-over-expressing parasites were reduced in their ability to destroy mammalian cell monolayers, raising the intriguing possibility that EhSIAF over-expression caused signaling defects or resulted in a dominant negative phenotype. Over-expression of EhSIAF and EhPTPA also resulted in decreased motility in a transwell motility assay. Thus, we have confirmed that two genes that are upregulated by ROS confer increased resistance to oxidative stress and have identified an unexpected role of EhSIAF and EhPTPA in host cell adherence and a role of EhSIAF in parasite virulence. Our data imply that stress response genes may play multi-factorial roles in amoebic pathogenesis.
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Affiliation(s)
- Elena Rastew
- Department of Internal Medicine, Stanford University School of Medicine, Stanford, CA, USA
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20
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Bosch DE, Wittchen ES, Qiu C, Burridge K, Siderovski DP. Unique structural and nucleotide exchange features of the Rho1 GTPase of Entamoeba histolytica. J Biol Chem 2011; 286:39236-46. [PMID: 21930699 PMCID: PMC3234748 DOI: 10.1074/jbc.m111.253898] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 09/13/2011] [Indexed: 01/28/2023] Open
Abstract
The single-celled human parasite Entamoeba histolytica possesses a dynamic actin cytoskeleton vital for its intestinal and systemic pathogenicity. The E. histolytica genome encodes several Rho family GTPases known to regulate cytoskeletal dynamics. EhRho1, the first family member identified, was reported to be insensitive to the Rho GTPase-specific Clostridium botulinum C3 exoenzyme, raising the possibility that it may be a misclassified Ras family member. Here, we report the crystal structures of EhRho1 in both active and inactive states. EhRho1 is activated by a conserved switch mechanism, but diverges from mammalian Rho GTPases in lacking a signature Rho insert helix. EhRho1 engages a homolog of mDia, EhFormin1, suggesting a role in mediating serum-stimulated actin reorganization and microtubule formation during mitosis. EhRho1, but not a constitutively active mutant, interacts with a newly identified EhRhoGDI in a prenylation-dependent manner. Furthermore, constitutively active EhRho1 induces actin stress fiber formation in mammalian fibroblasts, thereby identifying it as a functional Rho family GTPase. EhRho1 exhibits a fast rate of nucleotide exchange relative to mammalian Rho GTPases due to a distinctive switch one isoleucine residue reminiscent of the constitutively active F28L mutation in human Cdc42, which for the latter protein, is sufficient for cellular transformation. Nonconserved, nucleotide-interacting residues within EhRho1, revealed by the crystal structure models, were observed to contribute a moderating influence on fast spontaneous nucleotide exchange. Collectively, these observations indicate that EhRho1 is a bona fide member of the Rho GTPase family, albeit with unique structural and functional aspects compared with mammalian Rho GTPases.
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Affiliation(s)
| | | | | | - Keith Burridge
- Lineberger Comprehensive Cancer Center and
- the Department of Cell and Developmental Biology
- University of North Carolina McAllister Heart Institute, The University of North Carolina, Chapel Hill, North Carolina 27599-7365
| | - David P. Siderovski
- From the Department of Pharmacology
- University of North Carolina Neuroscience Center
- Lineberger Comprehensive Cancer Center and
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21
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A C2 domain protein kinase initiates phagocytosis in the protozoan parasite Entamoeba histolytica. Nat Commun 2011; 2:230. [PMID: 21407196 DOI: 10.1038/ncomms1199] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 01/19/2010] [Indexed: 11/08/2022] Open
Abstract
Phagocytosis is a process whereby particles are taken in by cells through mechanisms superficially similar to those for endocytosis. It serves a wide range of functions, from providing nutrition in unicellular organisms to initiation of both innate and adaptive immunity in vertebrates. In the protozoan parasite Entamoeba histolytica, it has an essential role in survival and pathogenesis. In this study, we show that EhC2PK, a C2-domain-containing protein kinase, and the Ca²(+) and actin-binding protein, EhCaBP1, are involved in the initiation of phagocytosis in E. histolytica. Conditional suppression of EhC2PK expression and overexpression of a mutant form reveals its role in the initiation of phagocytic cups. EhC2PK binds phosphatidylserine in the presence of Ca²(+) and thereby recruits EhCaBP1 and actin to the membrane. Identification of these proteins in phagocytosis is an important step in amoebic biology and these molecules could be the important targets for developing novel therapies against amoebiasis.
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Downregulation of an Entamoeba histolytica rhomboid protease reveals roles in regulating parasite adhesion and phagocytosis. EUKARYOTIC CELL 2010; 9:1283-93. [PMID: 20581296 DOI: 10.1128/ec.00015-10] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Entamoeba histolytica is a deep-branching eukaryotic pathogen. Rhomboid proteases are intramembrane serine proteases, which cleave transmembrane proteins in, or in close proximity to, their transmembrane domain. We have previously shown that E. histolytica contains a single functional rhomboid protease (EhROM1) and has unique substrate specificity. EhROM1 is present on the trophozoite surface and relocalizes to internal vesicles during erythrophagocytosis and to the base of the cap during surface receptor capping. In order to further examine the biological function of EhROM1 we downregulated EhROM1 expression by >95% by utilizing the epigenetic silencing mechanism of the G3 parasite strain. Despite the observation that EhROM1 relocalized to the cap during surface receptor capping, EhROM1 knockdown [ROM(KD)] parasites had no gross changes in cap formation or complement resistance. However, ROM(KD) parasites demonstrated decreased host cell adhesion, a result recapitulated by treatment of wild-type parasites with DCI, a serine protease inhibitor with activity against rhomboid proteases. The reduced adhesion phenotype of ROM(KD) parasites was noted exclusively with healthy cells, and not with apoptotic cells. Additionally, ROM(KD) parasites had decreased phagocytic ability with reduced ingestion of healthy cells, apoptotic cells, and rice starch. Decreased phagocytic ability is thus independent of the reduced adhesion phenotype, since phagocytosis of apoptotic cells was reduced despite normal adhesion levels. The defect in host cell adhesion was not explained by altered expression or localization of the heavy subunit of the Gal/GalNAc surface lectin. These results suggest no significant role of EhROM1 in complement resistance but unexpected roles in parasite adhesion and phagocytosis.
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23
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Sohn HJ, Kim JH, Shin MH, Song KJ, Shin HJ. The Nf-actin gene is an important factor for food-cup formation and cytotoxicity of pathogenic Naegleria fowleri. Parasitol Res 2010; 106:917-24. [PMID: 20143092 DOI: 10.1007/s00436-010-1760-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2009] [Accepted: 01/13/2010] [Indexed: 01/09/2023]
Abstract
Naegleria fowleri destroys target cells by trogocytosis, a phagocytosis mechanism, and a process of piecemeal ingestion of target cells by food-cups. Phagocytosis is an actin-dependent process that involves polymerization of monomeric G-actin into filamentous F-actin. However, despite the numerous studies concerning phagocytosis, its role in the N. fowleri food-cup formation related with trogocytosis has been poorly reported. In this study, we cloned and characterized an Nf-actin gene to elucidate the role of Nf-actin gene in N. fowleri pathogenesis. The Nf-actin gene is composed of 1,128-bp and produced a 54.1-kDa recombinant protein (Nf-actin). The sequence identity was 82% with nonpathogenic Naegleria gruberi but has no sequence identity with other mammals or human actin gene. Anti-Nf-actin polyclonal antibody was produced in BALB/c mice immunized with recombinant Nf-actin. The Nf-actin was localized on the cytoplasm, pseudopodia, and especially, food-cup structure (amoebastome) in N. fowleri trophozoites using immunofluorescence assay. When N. fowleri co-cultured with Chinese hamster ovary cells, Nf-actin was observed to localize around on phagocytic food-cups. We also observed that N. fowleri treated with cytochalasin D as actin polymerization inhibitor or transfected with antisense oligomer of Nf-actin gene had shown the reduced ability of food-cup formation and in vitro cytotoxicity. Finally, it suggests that Nf-actin plays an important role in phagocytic activity of pathogenic N. fowleri.
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Affiliation(s)
- Hae-Jin Sohn
- Department of Microbiology, Ajou University School of Medicine, Suwon, South Korea
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24
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Histomonas meleagridis possesses three α-actinins immunogenic to its hosts. Mol Biochem Parasitol 2010; 169:101-7. [DOI: 10.1016/j.molbiopara.2009.10.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 10/02/2009] [Accepted: 10/26/2009] [Indexed: 11/18/2022]
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25
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Luo Y, Pollard JW, Casadevall A. Fcgamma receptor cross-linking stimulates cell proliferation of macrophages via the ERK pathway. J Biol Chem 2009; 285:4232-4242. [PMID: 19996316 DOI: 10.1074/jbc.m109.037168] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Macrophage proliferation can be stimulated by phagocytosis and by cross-linking of Fcgamma receptors (FcgammaR). In this study, we investigated the role of FcgammaR and the signaling cascades that link FcgammaR activation to cell cycle progression. This effect was mediated by the activating FcgammaR, including FcgammaRI and III, via their Fcgamma subunit. Further investigation revealed that the cell cycle machinery was activated by FcgammaR cross-linking through downstream signaling events. Specifically, we identified the extracellular signal-regulated kinase (ERK) signaling pathway as a mediator of signals from FcgammaR activation to cyclin D1 expression, because cyclin D1 expression associated with FcgammaR cross-linking was attenuated by specific inhibitors of the ERK1/2 signaling pathway, PD98059 and U0126 and the spleen tyrosine kinase (Syk) inhibitor, Piceatannol. Our findings establish a link between the ERK activation and cell cycle signaling pathways, thus providing a causal mechanism by which FcgammaR activation produces a mitogenic effect that stimulates macrophage proliferation. Macrophage mitosis following FcgammaR activation could potentially affect the outcome of macrophage interactions with intracellular pathogens. In addition, our results suggest the possibility of new treatment options for certain infectious diseases, chronic inflammatory diseases, and leukemias based on interference with FcgammaR-stimulated macrophage cell proliferation.
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Affiliation(s)
- Yong Luo
- From the Departments of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Jeffrey W Pollard
- Departments of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York 10461; Departments of Obstetrics & Gynecology and Women's Health, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Arturo Casadevall
- From the Departments of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461; Departments of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461.
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26
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Nakada-Tsukui K, Okada H, Mitra BN, Nozaki T. Phosphatidylinositol-phosphates mediate cytoskeletal reorganization during phagocytosis via a unique modular protein consisting of RhoGEF/DH and FYVE domains in the parasitic protozoonEntamoeba histolytica. Cell Microbiol 2009; 11:1471-91. [DOI: 10.1111/j.1462-5822.2009.01341.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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27
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Baxt LA, Baker RP, Singh U, Urban S. An Entamoeba histolytica rhomboid protease with atypical specificity cleaves a surface lectin involved in phagocytosis and immune evasion. Genes Dev 2008; 22:1636-46. [PMID: 18559479 PMCID: PMC2428061 DOI: 10.1101/gad.1667708] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Rhomboid proteases are membrane-embedded enzymes conserved in all kingdoms of life, but their cellular functions across evolution are largely unknown. Prior work has uncovered a role for rhomboid enzymes in host cell invasion by malaria and related intracellular parasites, but this is unlikely to be a widespread function, even in pathogens, since rhomboid proteases are also conserved in unrelated protozoa that maintain an extracellular existence. We examined rhomboid function in Entamoeba histolytica, an extracellular, parasitic ameba that is second only to malaria in medical burden globally. Despite its large genome, E. histolytica encodes only one rhomboid (EhROM1) with residues necessary for protease activity. EhROM1 displayed atypical substrate specificity, being able to cleave Plasmodium adhesins but not the canonical substrate Drosophila Spitz. We searched for substrates encoded in the ameba genome and found EhROM1 was able to cleave a cell surface lectin specifically. In E. histolytica trophozoites, EhROM1 changed localization to vesicles during phagocytosis and to the posterior cap structure during surface receptor shedding for immune evasion, in both cases colocalizing with lectins. Collectively these results implicate rhomboid proteases for the first time in immune evasion and suggest that a common function of rhomboid enzymes in widely divergent protozoan pathogens is to break down adhesion proteins.
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Affiliation(s)
- Leigh A Baxt
- Department of Internal Medicine and Microbiology, Stanford University School of Medicine, Stanford, CA 94305, USA
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28
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Jain R, Santi-Rocca J, Padhan N, Bhattacharya S, Guillen N, Bhattacharya A. Calcium-binding protein 1 of Entamoeba histolytica transiently associates with phagocytic cups in a calcium-independent manner. Cell Microbiol 2008; 10:1373-89. [PMID: 18341598 DOI: 10.1111/j.1462-5822.2008.01134.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Ruchi Jain
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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29
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Linardopoulou EV, Parghi SS, Friedman C, Osborn GE, Parkhurst SM, Trask BJ. Human subtelomeric WASH genes encode a new subclass of the WASP family. PLoS Genet 2008; 3:e237. [PMID: 18159949 PMCID: PMC2151093 DOI: 10.1371/journal.pgen.0030237] [Citation(s) in RCA: 165] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2007] [Accepted: 10/19/2007] [Indexed: 12/17/2022] Open
Abstract
Subtelomeres are duplication-rich, structurally variable regions of the human genome situated just proximal of telomeres. We report here that the most terminally located human subtelomeric genes encode a previously unrecognized third subclass of the Wiskott-Aldrich Syndrome Protein family, whose known members reorganize the actin cytoskeleton in response to extracellular stimuli. This new subclass, which we call WASH, is evolutionarily conserved in species as diverged as Entamoeba. We demonstrate that WASH is essential in Drosophila. WASH is widely expressed in human tissues, and human WASH protein colocalizes with actin in filopodia and lamellipodia. The VCA domain of human WASH promotes actin polymerization by the Arp2/3 complex in vitro. WASH duplicated to multiple chromosomal ends during primate evolution, with highest copy number reached in humans, whose WASH repertoires vary. Thus, human subtelomeres are not genetic junkyards, and WASH's location in these dynamic regions could have advantageous as well as pathologic consequences. Human subtelomeres are rearrangement-prone regions near chromosome ends. They are concentrations of large, recent interchromosomal duplications. Over half of subtelomeric sequences changed copy number or location since humans and chimpanzee diverged, and subtelomeric content varies greatly among humans. Despite this dynamic activity, subtelomeres contain genes. We report the discovery of genes defining a previously unrecognized third subclass of the Wiskott-Aldrich Syndrome protein (WASP) family within human subtelomeres. The known WASP family members reorganize actin structures in cells in response to various signals, thereby causing cells to change shape and/or move. Representatives of this newly identified subclass, called WASH, exist in many other species, even in Entamoeba and slime mold. Like other WASP family members, WASH colocalizes with actin at the cell periphery and promotes actin polymerization in vitro. Flies lacking WASH die before becoming adults, demonstrating that WASH is critical for survival, and its function is distinct from that of the two other WASP subclasses, Wasp and Scar. Identification of the WASH subclass opens the way for future elucidation of WASH's role in the life cycles of diverse organisms, the implications of human variation in WASH copy number, and the consequences of WASH's location in dynamic telomere-adjacent regions.
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Affiliation(s)
- Elena V Linardopoulou
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Sean S Parghi
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Cynthia Friedman
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Gregory E Osborn
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Susan M Parkhurst
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Barbara J Trask
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- * To whom correspondence should be addressed. E-mail:
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30
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Virel A, Addario B, Backman L. Characterization of Entamoeba histolytica α-actinin2. Mol Biochem Parasitol 2007; 154:82-9. [PMID: 17537529 DOI: 10.1016/j.molbiopara.2007.04.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 04/16/2007] [Accepted: 04/17/2007] [Indexed: 10/23/2022]
Abstract
We have cloned and characterized a second alpha-actinin isoform in Entamoeba histolytica. This protein, alpha-actinin2, has a N-terminal actin-binding domain, a C-terminal calcium-binding domain and an intervening rod domain containing two spectrin repeats. The protein binds and cross-links actin filaments in a calcium-dependent manner. Therefore alpha-actinin2 is a genuine alpha-actinin except for the shorter rod domain compared to the rod domain of isoforms of higher organisms. A alpha-actinin-like protein has previous been implicated in the adherence to the host cell and infection. It is therefore possible that alpha-actinin2 is involved in mechanism of infection, and in particular in reorganisation of the parasite's cytoskeleton that follows on adherence. E. histolytica alpha-actinin2 represents one of the first members of the spectrin superfamily where well defined spectrin repeats are found. The isolation and characterization of this second alpha-actinin isoform is valuable not only into the study of E. histolytica infection mechanisms, but also for understanding the evolution processes of the spectrin superfamily.
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Affiliation(s)
- Ana Virel
- Biochemistry, Umeå University, SE-901 87 Umeå, Sweden
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31
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Majumder S, Schmidt G, Lohia A, Aktories K. EhRho1, a RhoA-like GTPase of Entamoeba histolytica, is modified by clostridial glucosylating cytotoxins. Appl Environ Microbiol 2006; 72:7842-8. [PMID: 17056697 PMCID: PMC1694214 DOI: 10.1128/aem.01826-06] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridial glucosylating cytotoxins inactivate mammalian Rho GTPases by mono-O glucosylation of a conserved threonine residue located in the switch 1 region of the target protein. Here we report that EhRho1, a RhoA-like GTPase from the protozoan parasite Entamoeba histolytica, is glucosylated by clostridial cytotoxins. Recombinant glutathione S-transferase-EhRho1 and EhRho1 from cell lysate of Entamoeba histolytica were glucosylated by Clostridium difficile toxin B and Clostridium novyi alpha-toxin. In contrast, Clostridium difficile toxin A, which shares the same mammalian protein substrates with toxin B, did not modify EhRho1. Change of threonine 52 of EhRho1 to alanine prevented glucosylation by toxin B from Clostridium difficile and by alpha-toxin from Clostridium novyi, which suggests that the equivalent threonine residues are glucosylated in mammalian and Entamoeba Rho GTPases. Lethal toxin from Clostridium sordellii did not glucosylate EhRho1 but labeled several other substrate proteins in lysates from Entamoeba histolytica in the presence of UDP-[14C]glucose.
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32
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Welter BH, Powell RR, Laughlin RC, McGugan GC, Bonner M, King A, Temesvari LA. Entamoeba histolytica: Comparison of the role of receptors and filamentous actin among various endocytic processes. Exp Parasitol 2006; 113:91-9. [PMID: 16458294 DOI: 10.1016/j.exppara.2005.12.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Revised: 12/14/2005] [Accepted: 12/20/2005] [Indexed: 11/21/2022]
Abstract
Entamoeba histolytica is the causative agent of amoebic dysentery. Uptake of iron is critical for E. histolytica growth and iron-bound human transferrin (holo-transferrin) has been shown to serve as an iron source in vitro. Although a transferrin-binding protein has been identified in E. histolytica, the mechanism by which this iron source is taken up by this pathogen is not well understood. To gain insight into this process, the uptake of fluorescent-dextran, -holo-transferrin, and human red blood cells (hRBCs) was compared. Both dextran and transferrin were taken up in an apparent receptor-independent fashion as compared to hRBCs, which were taken up in a receptor-mediated fashion. Interestingly, the uptake of FITC-dextran and FITC-holo-transferrin differentially relied on an intact actin cytoskeleton suggesting that their internalization routes may be regulated independently.
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Affiliation(s)
- B H Welter
- Department of Biological Sciences, Clemson University, SC 29634, USA
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Powell RR, Welter BH, Hwu R, Bowersox B, Attaway C, Temesvari LA. Entamoeba histolytica: FYVE-finger domains, phosphatidylinositol 3-phosphate biosensors, associate with phagosomes but not fluid filled endosomes. Exp Parasitol 2006; 112:221-31. [PMID: 16387299 DOI: 10.1016/j.exppara.2005.11.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 11/09/2005] [Accepted: 11/10/2005] [Indexed: 11/24/2022]
Abstract
Endocytosis is an important virulence function for Entamoeba histolytica, the causative agent of amoebic dysentery. Although a number of E. histolytica proteins that regulate this process have been identified, less is known about the role of lipids. In other systems, phosphatidylinositol 3-phosphate (PI3P), a product of phosphatidylinositol 3-kinase (PI 3-kinase), has been shown to be required for endocytosis. FYVE-finger domains are protein motifs that bind specifically to PI3P. Using a PI3P biosensor consisting of glutathione-S-transferase (GST) fused to two tandem FYVE-finger domains, we have localized PI3P to phagosomes but not fluid-phase pinosomes in E. histolytica, suggesting a role for PI3P in phagocytosis. Treatment of cells with PI 3-kinase inhibitors impaired GST-2 x FYVE-phagosome association supporting the authenticity of the biosensor staining. However, treatment with PI 3-kinase inhibitors did not inhibit E. histolytica-particle interaction, indicating that PI3P is not required for the initial step, but is required for subsequent steps of phagocytosis.
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Affiliation(s)
- R R Powell
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
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Virel A, Backman L. Characterization of Entamoeba histolytica alpha-actinin. Mol Biochem Parasitol 2005; 145:11-7. [PMID: 16219372 DOI: 10.1016/j.molbiopara.2005.09.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2005] [Revised: 08/18/2005] [Accepted: 09/07/2005] [Indexed: 10/25/2022]
Abstract
We have cloned, expressed and characterized a alpha-actinin-like protein of Entamoeba histolytica. Analysis of the primary structure reveals that the essential domains of the alpha-actinin protein family are conserved: an N-terminus actin-binding domain, a C-terminus calcium-binding domain and a central helical rod domain. However, the rod domain of this Entamoeba protein is considerably shorter than the rod domain in alpha-actinins of higher organisms. The cloned Entamoeba 63 kDa protein is recognized by conventional alpha-actinin antibodies as well as binds and cross-links filamentous actin and calcium ions in the same manner as alpha-actinins. Despite the shorter rod domain this protein has conserved the most important functions of alpha-actinins. Therefore, it is suggested that this 63 kDa protein is an atypical and ancestral alpha-actinin.
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Affiliation(s)
- Ana Virel
- Biochemistry, Umeå University, SE-901 87 Umeå, Sweden
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Sahoo N, Labruyère E, Bhattacharya S, Sen P, Guillén N, Bhattacharya A. Calcium binding protein 1 of the protozoan parasite Entamoeba histolytica interacts with actin and is involved in cytoskeleton dynamics. J Cell Sci 2005; 117:3625-34. [PMID: 15252130 DOI: 10.1242/jcs.01198] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Blocking expression of EhCaBP1, a calmodulin-like, four EF-hand protein from the protozoan parasite Entamoeba histolytica, resulted in inhibition of cellular proliferation. In this paper we report that EhCaBP1 is involved in dynamic changes of the actin cytoskeleton. Both endocytosis and phagocytosis were severely impaired in cells where EhCaBP1 expression was blocked by inducible expression of the antisense RNA. In wild-type cells both actin and EhCaBP1 were found to co-localize in phagocytic cups and in pseudopods. However, in antisense-blocked cells the phagocytic cup formation is affected. Analysis of the staining patterns in the presence and absence of actin dynamics inhibitors, jasplakinolide and cytochalasin D suggested that EhCaBP1 and polymerized F-actin co-localize on membrane protrusions. Direct interaction between soluble EhCaBP1 and F-actin was further demonstrated by a co-sedimentation assay. A variant of EhCaBP1 did not bind F-actin showing the specificity of the interaction between EhCaBP1 and actin. There is no significant change in the kinetics of in vitro polymerization of actin in presence of EhCaBP1, indicating that EhCaBP1 does not affect filament treadmilling. In addition, using atomic force microscopy; it was found that filaments of F-actin, polymerized in presence of EhCaBP1, were thinner. These results indicate that EhCaBP1 may be involved in dynamic membrane restructuring at the time of cell pseudopod formation, phagocytosis and endocytosis in a process mediated by direct binding of EhCaBP1 to actin, affecting the bundling of actin filaments.
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Affiliation(s)
- Nivedita Sahoo
- School of Life Sciences, Jawaharlal Nehru University, Aruna Asaf Ali Marg, New Delhi, 110067 India
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Guzmán-Medrano R, Castillo-Juárez BA, García-Pérez RM, Salas-Casas A, Orozco E, Rodríguez MA. Entamoeba histolytica: alterations in EhRabB protein in a phagocytosis deficient mutant correlate with the Entamoeba dispar RabB sequence. Exp Parasitol 2005; 110:259-64. [PMID: 15955321 DOI: 10.1016/j.exppara.2005.03.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Revised: 03/02/2005] [Accepted: 03/05/2005] [Indexed: 11/20/2022]
Abstract
We analyzed the expression and location of EhRabB in clone L-6, a phagocytosis-deficient mutant of Entamoeba histolytica, in comparison with the wild-type clone A. Intriguingly, trophozoites of clone L-6 express more EhRabB than those of clone A. However, the majority of EhRabB-containing vesicles remained in the cytoplasm of clone L-6 during phagocytosis. To investigate molecular alterations in EhRabB of clone L-6 we compared the EhrabB gene sequences from clones L-6 and A. We also isolated, sequenced and compared the RabB protein of Entamoeba dispar. Results showed that EhrabB gene of clone L-6 is 98.2 and 94.1% identical to rabB genes of E. dispar and clone A, respectively. The rabB genes from clone A and E. dispar have 92.2% identity. Four out of five amino acids changes in RabB proteins of clone L-6 and E. dispar are shared. These changes may alter the binding of effector proteins and the specific subcellular location of EhRabB.
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Affiliation(s)
- Rebeca Guzmán-Medrano
- Departamento de Patología Experimental, Centro de Investigación y de Estudios Avanzados del IPN. A.P. 14-740, Mexico, D.F. 07000, Mexico
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Loftus B, Anderson I, Davies R, Alsmark UCM, Samuelson J, Amedeo P, Roncaglia P, Berriman M, Hirt RP, Mann BJ, Nozaki T, Suh B, Pop M, Duchene M, Ackers J, Tannich E, Leippe M, Hofer M, Bruchhaus I, Willhoeft U, Bhattacharya A, Chillingworth T, Churcher C, Hance Z, Harris B, Harris D, Jagels K, Moule S, Mungall K, Ormond D, Squares R, Whitehead S, Quail MA, Rabbinowitsch E, Norbertczak H, Price C, Wang Z, Guillén N, Gilchrist C, Stroup SE, Bhattacharya S, Lohia A, Foster PG, Sicheritz-Ponten T, Weber C, Singh U, Mukherjee C, El-Sayed NM, Petri WA, Clark CG, Embley TM, Barrell B, Fraser CM, Hall N. The genome of the protist parasite Entamoeba histolytica. Nature 2005; 433:865-8. [PMID: 15729342 DOI: 10.1038/nature03291] [Citation(s) in RCA: 624] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2004] [Accepted: 12/02/2004] [Indexed: 11/08/2022]
Abstract
Entamoeba histolytica is an intestinal parasite and the causative agent of amoebiasis, which is a significant source of morbidity and mortality in developing countries. Here we present the genome of E. histolytica, which reveals a variety of metabolic adaptations shared with two other amitochondrial protist pathogens: Giardia lamblia and Trichomonas vaginalis. These adaptations include reduction or elimination of most mitochondrial metabolic pathways and the use of oxidative stress enzymes generally associated with anaerobic prokaryotes. Phylogenomic analysis identifies evidence for lateral gene transfer of bacterial genes into the E. histolytica genome, the effects of which centre on expanding aspects of E. histolytica's metabolic repertoire. The presence of these genes and the potential for novel metabolic pathways in E. histolytica may allow for the development of new chemotherapeutic agents. The genome encodes a large number of novel receptor kinases and contains expansions of a variety of gene families, including those associated with virulence. Additional genome features include an abundance of tandemly repeated transfer-RNA-containing arrays, which may have a structural function in the genome. Analysis of the genome provides new insights into the workings and genome evolution of a major human pathogen.
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Affiliation(s)
- Brendan Loftus
- TIGR, 9712 Medical Center Drive, Rockville, Maryland 20850, USA.
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Labruyère E, Zimmer C, Galy V, Olivo-Marin JC, Guillén N. EhPAK, a member of the p21-activated kinase family, is involved in the control of Entamoeba histolytica migration and phagocytosis. J Cell Sci 2003; 116:61-71. [PMID: 12456716 DOI: 10.1242/jcs.00190] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Entamoeba histolytica migration is essential for the development of amoebiasis, a human disease characterised by invasion and destruction of tissues. Amoebic motility requires both polarisation of the cell and formation of a predominant pseudopod. As p21-activated kinases PAKs are known to regulate eukaryotic cell motility and morphology, we investigated the role of PAK in E. histolytica. We showed that the C-terminal domain of EhPAK comprised a constitutive kinase activity in vitro and that overproduction of this fragment, in E. histolytica, caused a significant reduction in amoeboid migration, as measured by dynamic image analysis, indicating an involvement of EhPAK in this process. A dramatic loss of polarity, as indicated by the increased number of membrane extensions all around E. histolytica, was also observed, suggesting that the N-terminal domain of EhPAK was necessary for maintenance of cell polarity. To support this view, we showed that despite the absence of the consensus motif to bind to Rac and Cdc42, the N-terminal domain of EhPAK bound to Rac1, suggesting that the N-terminal region was a regulatory domain. In addition, we also found an increased rate of human red blood cell phagocytosis, suggesting for the first time an active role for a PAK protein in this process. Taking together, the results suggest strongly that EhPAK is a key regulatory element in polarity, motility and phagocytosis of E. histolytica.
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Affiliation(s)
- Elisabeth Labruyère
- Unité de Biologie Cellulaire du Parasitisme, INSERM U389, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris Cedex 15, France.
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Abstract
It is an exciting time in the study of Entamoeba histolytica. Over the past two years, the natural history and burden of disease in humans has been redefined, mucosal immune responses associated with protection identified, and the developmental regulation of encystation outlined. The number of genes sequenced has increased from a few hundred to a few thousand, and study of the genome structure is revealing unusual repetitive elements and plasticity. DNA microarrays promise the first ability to examine global patterns of mRNA abundance. The mechanism of transcriptional control via histone modifications and sequence-specific DNA-binding proteins are to be delineated. Advances in cell biology are providing new insights into invasion through the intestinal epithelium.
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Affiliation(s)
- William A Petri
- Division of Infectious Diseases, Room 2115, MR4 Building, Lane Road, PO Box 801340, University of Virginia Health System, Charlottesville, Virginia 22908-1340, USA.
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40
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Abstract
Few organisms are more aptly named than Entamoeba histolytica, an intestinal protozoan parasite that can lyse and destroy human tissue. Within the past four years, new models of E. histolytica infection have begun to illuminate how amoebic trophozoites cause intestinal disease and liver abscess, and have expanded our understanding of the remarkable killing ability of this parasite. Here, I summarize recent work on the interactions between E. histolytica and human intestine, and between E. histolytica and hepatocytes, and discuss what these studies tell us about the role of inflammation and programmed cell death in the pathogenesis of amoebiasis.
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Affiliation(s)
- S L Stanley
- Depts Medicine and Molecular Microbiology, Washington University School of Medicine, St Louis, MO 63110, USA.
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