1
|
Reyes-López M, Piña-Vázquez C, Pérez-Salazar E, de la Garza M. Endocytosis, signal transduction and proteolytic cleaving of human holotransferrin in Entamoeba histolytica. Int J Parasitol 2020; 50:959-967. [PMID: 32822678 DOI: 10.1016/j.ijpara.2020.05.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 04/03/2020] [Accepted: 05/08/2020] [Indexed: 01/15/2023]
Abstract
Amoebiasis is a parasitic infection of the human large intestine caused by Entamoeba histolytica; this disease mainly affects people from developing countries. To survive, this primitive protozoan has a high demand for iron, and it uses host iron proteins upon invasion. Transferrin (Tf) is a plasma iron-binding protein that transports and delivers iron to all cells. Iron-loaded Tf (holoTf) in humans can support the proliferation of amoebae in vitro by binding to an amoebic TfR (EhTfR), and amoebae endocytose it inside clathrin-coated vesicles. In this study, it was found that EhTfR phosphorylation is required for human holoTf endocytosis by E. histolytica. Once this complex is endocytosed, human holoTf could be degraded with a nutritional purpose by cysteine proteases. HoloTf endocytosis initiates the activation of the mitogen-activated protein kinases (MAPKs) and focal adhesion kinase (FAK) pathways, which induce cell proliferation with phosphoinositide 3-kinase (PI-3 K) and Ca2+ involvement. In the first minutes after holoTf is endocytosed, several proteins are phosphorylated including transketolase, enolase, L-myo-inositol-1-phosphate synthase and phosphoglucomutase, which control carbohydrate metabolism, and heat shock protein-70. The study of these proteins and their signal transduction pathways could be useful for developing future therapies.
Collapse
Affiliation(s)
- Magda Reyes-López
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Ave. IPN 2508, Col. Zacatenco, CdMx 07360, Mexico
| | - Carolina Piña-Vázquez
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Ave. IPN 2508, Col. Zacatenco, CdMx 07360, Mexico
| | - Eduardo Pérez-Salazar
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Ave. IPN 2508, Col. Zacatenco, CdMx 07360, Mexico
| | - Mireya de la Garza
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Ave. IPN 2508, Col. Zacatenco, CdMx 07360, Mexico.
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Elhasi T, Blomberg A. Integrins in disguise - mechanosensors in Saccharomyces cerevisiae as functional integrin analogues. MICROBIAL CELL 2019; 6:335-355. [PMID: 31404395 PMCID: PMC6685044 DOI: 10.15698/mic2019.08.686] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The ability to sense external mechanical stimuli is vital for all organisms. Integrins are transmembrane receptors that mediate bidirectional signalling between the extracellular matrix (ECM) and the cytoskeleton in animals. Thus, integrins can sense changes in ECM mechanics and can translate these into internal biochemical responses through different signalling pathways. In the model yeast species Saccharomyces cerevisiae there are no proteins with sequence similarity to mammalian integrins. However, we here emphasise that the WSC-type (Wsc1, Wsc2, and Wsc3) and the MID-type (Mid2 and Mtl1) mechanosensors in yeast act as partial functional integrin analogues. Various environmental cues recognised by these mechanosensors are transmitted by a conserved signal transduction cascade commonly referred to as the PKC1-SLT1 cell wall integrity (CWI) pathway. We exemplify the WSC- and MID-type mechanosensors functional analogy to integrins with a number of studies where they resemble the integrins in terms of both mechanistic and molecular features as well as in the overall phenotypic consequences of their activity. In addition, many important components in integrin-dependent signalling in humans are conserved in yeast; for example, Sla1 and Sla2 are homologous to different parts of human talin, and we propose that they together might be functionally similar to talin. We also propose that the yeast cell wall is a prominent cellular feature involved in sensing a number of external factors and subsequently activating different signalling pathways. In a hypothetical model, we propose that nutrient limitations modulate cell wall elasticity, which is sensed by the mechanosensors and results in filamentous growth. We believe that mechanosensing is a somewhat neglected aspect of yeast biology, and we argue that the physiological and molecular consequences of signal transduction initiated at the cell wall deserve more attention.
Collapse
Affiliation(s)
- Tarek Elhasi
- Dept. of Chemistry and Molecular Biology, Univ. of Gothenburg, Sweden
| | - Anders Blomberg
- Dept. of Chemistry and Molecular Biology, Univ. of Gothenburg, Sweden
| |
Collapse
|
4
|
Verma K, Srivastava VK, Datta S. Rab GTPases take centre stage in understanding Entamoeba histolytica biology. Small GTPases 2018; 11:320-333. [PMID: 30273093 DOI: 10.1080/21541248.2018.1528840] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Rab GTPases constitute the largest subgroup in the Ras superfamily of GTPases. It is well established that different Rab GTPases are localized in discrete subcellular localization and regulate the membrane trafficking in nearly all eukaryotic cells. Rab GTPase diversity is often regarded as an expression of vesicular trafficking complexity. The pathogenic amoeba Entamoeba histolytica harbours 91 Rab GTPases which is the highest among the currently available genome sequences from the eukaryotic kingdom. Here, we review the current status of amoebic Rab GTPases diversity, unique biochemical and structural features and summarise their predicted regulators. We discuss how amoebic Rab GTPases are involved in cellular processes such as endocytosis, phagocytosis, and invasion of host cellular components, which are essential for parasite survival and virulence.
Collapse
Affiliation(s)
- Kuldeep Verma
- Institute of Science, Nirma University , Ahmedabad, Gujarat, India.,Regional Centre for Biotechnology, NCR Biotech Science Cluster , Faridabad, India
| | | | - Sunando Datta
- Department of Biological Science, Indian Institute of Science Education and Research Bhopal , Bhauri, India
| |
Collapse
|
5
|
Invadosome-Mediated Human Extracellular Matrix Degradation by Entamoeba histolytica. Infect Immun 2018; 86:IAI.00287-18. [PMID: 29914929 DOI: 10.1128/iai.00287-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 06/13/2018] [Indexed: 02/03/2023] Open
Abstract
Entamoeba histolytica is a protozoan parasite that causes invasive amoebiasis when it invades the human colon. Tissue invasion requires a shift from an adhesive lifestyle in the colonic lumen to a motile and extracellular matrix (ECM) degradative lifestyle in the colonic tissue layers. How the parasite regulates these two lifestyles is largely unknown. Previously, we showed that silencing the E. histolytica surface metalloprotease EhMSP-1 results in parasites that are hyperadherent and less motile. To better understand the molecular mechanism of this phenotype, we now show that the parasites with EhMSP-1 silenced cannot efficiently form specialized dot-like polymerized actin (F actin) structures upon interaction with the human ECM component fibronectin. We characterized these F actin structures and found that they are very short-lived structures that are the sites of fibronectin degradation. Motile mammalian cells form F actin structures called invadosomes that are similar in stability and function to these amoebic actin dots. Therefore, we propose here that E. histolytica forms amoebic invadosomes to facilitate colonic tissue invasion.
Collapse
|
6
|
Manich M, Hernandez-Cuevas N, Ospina-Villa JD, Syan S, Marchat LA, Olivo-Marin JC, Guillén N. Morphodynamics of the Actin-Rich Cytoskeleton in Entamoeba histolytica. Front Cell Infect Microbiol 2018; 8:179. [PMID: 29896453 PMCID: PMC5986921 DOI: 10.3389/fcimb.2018.00179] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 05/09/2018] [Indexed: 02/01/2023] Open
Abstract
Entamoeba histolytica is the anaerobic protozoan parasite responsible for human amoebiasis, the third most deadly parasitic disease worldwide. This highly motile eukaryotic cell invades human tissues and constitutes an excellent experimental model of cell motility and cell shape deformation. The absence of extranuclear microtubules in Entamoeba histolytica means that the actin-rich cytoskeleton takes on a crucial role in not only amoebic motility but also other processes sustaining pathogenesis, such as the phagocytosis of human cells and the parasite's resistance of host immune responses. Actin is highly conserved among eukaryotes, although diverse isoforms exist in almost all organisms studied to date. However, E. histolytica has a single actin protein, the structure of which differs significantly from those of its human homologs. Here, we studied the expression, structure and dynamics of actin in E. histolytica. We used molecular and cellular approaches to evaluate actin gene expression during intestinal invasion by E. histolytica trophozoites. Based on a three-dimensional structural bioinformatics analysis, we characterized protein domains differences between amoebic actin and human actin. Fine-tuned molecular dynamics simulations enabled us to examine protein motion and refine the three-dimensional structures of both actins, including elements potentially accounting for differences changes in the affinity properties of amoebic actin and deoxyribonuclease I. The dynamic, multifunctional nature of the amoebic cytoskeleton prompted us to examine the pleiotropic forms of actin structures within live E. histolytica cells; we observed the cortical cytoskeleton, stress fibers, "dot-like" structures, adhesion plates, and macropinosomes. In line with these data, a proteomics study of actin-binding proteins highlighted the Arp2/3 protein complex as a crucial element for the development of macropinosomes and adhesion plaques.
Collapse
Affiliation(s)
- Maria Manich
- BioImaging Unit, Institut Pasteur, Paris, France.,Cell Biology of Parasitism Unit, Institut Pasteur, Paris, France
| | | | - Juan D Ospina-Villa
- Instituto Politécnico Nacional, Escuela Nacional de Medicina y Homeopatía, Mexico City, Mexico
| | - Sylvie Syan
- Cell Biology of Parasitism Unit, Institut Pasteur, Paris, France
| | - Laurence A Marchat
- Instituto Politécnico Nacional, Escuela Nacional de Medicina y Homeopatía, Mexico City, Mexico
| | | | - Nancy Guillén
- Cell Biology of Parasitism Unit, Institut Pasteur, Paris, France.,Centre National de la Recherche Scientifique, CNRS-ERL9195, Paris, France
| |
Collapse
|
7
|
Ujang JA, Kwan SH, Ismail MN, Lim BH, Noordin R, Othman N. Proteome analysis of excretory-secretory proteins of Entamoeba histolytica HM1:IMSS via LC-ESI-MS/MS and LC-MALDI-TOF/TOF. Clin Proteomics 2016; 13:33. [PMID: 27895543 PMCID: PMC5120466 DOI: 10.1186/s12014-016-9135-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 11/16/2016] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Excretory-secretory (ES) proteins of E. histolytica are thought to play important roles in the host invasion, metabolism, and defence. Elucidation of the types and functions of E. histolytica ES proteins can further our understanding of the disease pathogenesis. Thus, the aim of this study is to use proteomics approach to better understand the complex ES proteins of the protozoa. METHODS E. histolytica ES proteins were prepared by culturing the trophozoites in protein-free medium. The ES proteins were identified using two mass spectrometry tools, namely, LC-ESI-MS/MS and LC-MALDI-TOF/TOF. The identified proteins were then classified according to their biological processes, molecular functions, and cellular components using the Panther classification system (PantherDB). RESULTS A complementary list of 219 proteins was identified; this comprised 201 proteins detected by LC-ESI-MS/MS and 107 proteins by LC-MALDI-TOF/TOF. Of the 219 proteins, 89 were identified by both mass-spectrometry systems, while 112 and 18 proteins were detected exclusively by LC-ESI-MS/MS and LC-MALDI-TOF/TOF respectively. Biological protein functional analysis using PantherDB showed that 27% of the proteins were involved in metabolic processes. Using molecular functional and cellular component analyses, 35% of the proteins were found to be involved in catalytic activity, and 21% were associated with the cell parts. CONCLUSION This study showed that complementary use of LC-ESI-MS/MS and LC-MALDI-TOF/TOF has improved the identification of ES proteins. The results have increased our understanding of the types of proteins excreted/secreted by the amoeba and provided further evidence of the involvement of ES proteins in intestinal colonisation and evasion of the host immune system, as well as in encystation and excystation of the parasite.
Collapse
Affiliation(s)
- Jorim Anak Ujang
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Gelugor, Penang Malaysia
| | - Soon Hong Kwan
- Analytical Biochemistry Research Centre, Universiti Sains Malaysia, 11800 Gelugor, Penang Malaysia
| | - Mohd Nazri Ismail
- Analytical Biochemistry Research Centre, Universiti Sains Malaysia, 11800 Gelugor, Penang Malaysia
| | - Boon Huat Lim
- School of Health Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan Malaysia
| | - Rahmah Noordin
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Gelugor, Penang Malaysia
| | - Nurulhasanah Othman
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Gelugor, Penang Malaysia
| |
Collapse
|
8
|
Tyrosine phosphorylation/dephosphorylation of myosin II essential light chains of Entamoeba histolytica trophozoites regulates their motility. Mol Biochem Parasitol 2016; 208:49-55. [PMID: 27318258 DOI: 10.1016/j.molbiopara.2016.05.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/03/2016] [Accepted: 05/10/2016] [Indexed: 11/22/2022]
Abstract
Entamoeba histolytica trophozoites dwell in the human intestine as comensals although under still unclear circumstances become invasive and destroy the host tissues. For these activities, trophozoites relay on remarkable motility provided by the cytoskeleton organization. Amebic actin and some of its actin-associated proteins are well known, while components of the myosin II molecule, although predicted from the E. histolytica genome, need biochemical and functional characterization. Recently, an amebic essential light myosin II chain, named EhMLCI, was identified and reported to be phosphorylated in tyrosines. The phosphorylated form of the protein was associated with the soluble assembly incompetent conformation of the heavy myosin chains, while the non-phosphorylated protein was identified with filamentous heavy chains, organized in an assembly competent conformation. It was postulated that EhMLCI tyrosine phosphorylation could act as a negative regulator of myosin II activity by its phosphorylation/dephosphorylation cycles. To test this hypothesis, we constructed an expression vector containing an EhMLCI DNA sequence where two tyrosine residues, with strong probability of phosphorylation and fall within the single EF-hand domain that interacts with the N-terminus of myosin II heavy chains, were replaced by phenylalanines. Transfected trophozoites, expressing the mutant MutEhMLCI protein cannot process it, thereby not incorporated into the phosphorylation/dephosphorylation cycles required for myosin II activity, results in motility defective trophozoites.
Collapse
|
9
|
Bolaños V, Díaz-Martínez A, Soto J, Marchat LA, Sanchez-Monroy V, Ramírez-Moreno E. Kaempferol inhibits Entamoeba histolytica growth by altering cytoskeletal functions. Mol Biochem Parasitol 2015; 204:16-25. [PMID: 26620675 DOI: 10.1016/j.molbiopara.2015.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 10/30/2015] [Accepted: 11/20/2015] [Indexed: 11/27/2022]
Abstract
The flavonoid kaempferol obtained from Helianthemum glomeratum, an endemic Mexican medicinal herb used to treat gastrointestinal disorders, has been shown to inhibit growth of Entamoeba histolytica trophozoites in vitro; however, the mechanisms associated with this activity have not been documented. Several works reported that kaempferol affects cytoskeleton in mammalian cells. In order to gain insights into the action mechanisms involved in the anti-amoebic effect of kaempferol, here we evaluated the effect of this compound on the pathogenic events driven by the cytoskeleton during E. histolytica infection. We also carried out a two dimensional gel-based proteomic analysis to evidence modulated proteins that could explain the phenotypical changes observed in trophozoites. Our results showed that kaempferol produces a dose-dependent effect on trophozoites growth and viability with optimal concentration being 27.7 μM. Kaempferol also decreased adhesion, it increased migration and phagocytic activity, but it did not affect erythrocyte binding nor cytolytic capacity of E. histolytica. Congruently, proteomic analysis revealed that the cytoskeleton proteins actin, myosin II heavy chain and cortexillin II were up-regulated in response to kaempferol treatment. In conclusion, kaempferol anti-amoebic effects were associated with deregulation of proteins related with cytoskeleton, which altered invasion mechanisms.
Collapse
Affiliation(s)
- Verónica Bolaños
- Doctorado en Ciencias en Biotecnología, ENMyH, Instituto Politécnico Nacional, México City 07320, Mexico
| | - Alfredo Díaz-Martínez
- Posgrado en Biomedicina Molecular, ENMyH, Instituto Politécnico Nacional, México City 07320, Mexico
| | - Jacqueline Soto
- Posgrado en Biomedicina Molecular, ENMyH, Instituto Politécnico Nacional, México City 07320, Mexico; Doctorado en Ciencias en Biotecnología, ENMyH, Instituto Politécnico Nacional, México City 07320, Mexico
| | - Laurence A Marchat
- Posgrado en Biomedicina Molecular, ENMyH, Instituto Politécnico Nacional, México City 07320, Mexico; Doctorado en Ciencias en Biotecnología, ENMyH, Instituto Politécnico Nacional, México City 07320, Mexico
| | - Virginia Sanchez-Monroy
- Laboratorio Multidisciplinario de Investigación, Escuela Militar de Graduados de Sanidad, Universidad del Ejército y Fuerza Aérea, México City 11620, Mexico
| | - Esther Ramírez-Moreno
- Posgrado en Biomedicina Molecular, ENMyH, Instituto Politécnico Nacional, México City 07320, Mexico; Doctorado en Ciencias en Biotecnología, ENMyH, Instituto Politécnico Nacional, México City 07320, Mexico.
| |
Collapse
|
10
|
Marie C, Verkerke HP, Theodorescu D, Petri WA. A whole-genome RNAi screen uncovers a novel role for human potassium channels in cell killing by the parasite Entamoeba histolytica. Sci Rep 2015; 5:13613. [PMID: 26346926 PMCID: PMC4561901 DOI: 10.1038/srep13613] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 07/30/2015] [Indexed: 01/29/2023] Open
Abstract
The parasite Entamoeba histolytica kills human cells resulting in ulceration, inflammation and invasion of the colonic epithelium. We used the cytotoxic properties of ameba to select a genome-wide RNAi library to reveal novel host factors that control susceptibility to amebic killing. We identified 281 candidate susceptibility genes and bioinformatics analyses revealed that ion transporters were significantly enriched among susceptibility genes. Potassium (K+) channels were the most common transporter identified. Their importance was further supported by colon biopsy of humans with amebiasis that demonstrated suppressed K+ channel expression. Inhibition of human K+ channels by genetic silencing, pharmacologic inhibitors and with excess K+ protected diverse cell types from E. histolytica-induced death. Contact with E. histolytica parasites triggered K+ channel activation and K+ efflux by intestinal epithelial cells, which preceded cell killing. Specific inhibition of Ca2+-dependent K+ channels was highly effective in preventing amebic cytotoxicity in intestinal epithelial cells and macrophages. Blockade of K+ efflux also inhibited caspase-1 activation, IL-1β secretion and pyroptotic death in THP-1 macrophages. We concluded that K+ channels are host mediators of amebic cytotoxicity in multiple cells types and of inflammasome activation in macrophages.
Collapse
Affiliation(s)
- Chelsea Marie
- Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia USA
| | - Hans P Verkerke
- Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia USA
| | - Dan Theodorescu
- Department of Surgery, Department of Pharmacology, University of Colorado Comprehensive Cancer Center, University of Colorado, Denver, CO, USA
| | - William A Petri
- Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia USA
| |
Collapse
|
11
|
Lee YA, Kim KA, Min A, Shin MH. Amoebic PI3K and PKC is required for Jurkat T cell death induced by Entamoeba histolytica. THE KOREAN JOURNAL OF PARASITOLOGY 2014; 52:355-65. [PMID: 25246714 PMCID: PMC4170031 DOI: 10.3347/kjp.2014.52.4.355] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Revised: 05/29/2014] [Accepted: 06/04/2014] [Indexed: 01/01/2023]
Abstract
The enteric protozoan parasite Entamoeba histolytica is the causative agent of human amebiasis. During infection, adherence of E. histolytica through Gal/GalNAc lectin on the surface of the amoeba can induce caspase-3-dependent or -independent host cell death. Phosphorylinositol 3-kinase (PI3K) and protein kinase C (PKC) in E. histolytica play an important function in the adhesion, killing, or phagocytosis of target cells. In this study, we examined the role of amoebic PI3K and PKC in amoeba-induced apoptotic cell death in Jurkat T cells. When Jurkat T cells were incubated with E. histolytica trophozoites, phosphatidylserine (PS) externalization and DNA fragmentation in Jurkat cells were markedly increased compared to those of cells incubated with medium alone. However, when amoebae were pretreated with a PI3K inhibitor, wortmannin before being incubated with E. histolytica, E. histolytica-induced PS externalization and DNA fragmentation in Jurkat cells were significantly reduced compared to results for amoebae pretreated with DMSO. In addition, pretreatment of amoebae with a PKC inhibitor, staurosporine strongly inhibited Jurkat T cell death. However, E. histolytica-induced cleavage of caspase-3, -6, and -7 were not inhibited by pretreatment of amoebae with wortmannin or staurosporin. In addition, we found that amoebic PI3K and PKC have an important role on amoeba adhesion to host compartment. These results suggest that amebic PI3K and PKC activation may play an important role in caspase-independent cell death in Entamoeba-induced apoptosis.
Collapse
Affiliation(s)
- Young Ah Lee
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Kyeong Ah Kim
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Arim Min
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Myeong Heon Shin
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea
| |
Collapse
|
12
|
A functional study of nucleocytoplasmic transport signals of the EhNCABP166 protein from Entamoeba histolytica. Parasitology 2012; 139:1697-710. [PMID: 22906852 DOI: 10.1017/s0031182012001199] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
EhNCABP166 is an Entamoeba histolytica actin-binding protein that localizes to the nucleus and cytoplasm. Bioinformatic analysis of the EhNCABP166 amino acid sequence shows the presence of 3 bipartite nuclear localization signals (NLS) and a nuclear export signal (NES). The present study aimed to investigate the functionality of these signals in 3 ways. First, we fused each potential NLS to a cytoplasmic domain of ehFLN to determine whether the localization of this domain could be altered by the presence of the NLSs. Furthermore, the localization of each domain of EhNCABP166 was determined. Similarly, we generated mutations in the first block of bipartite signals from the domains that contained these signals. Additionally, we added an NES to 2 constructs that were then evaluated. We confirmed the intranuclear localization of EhNCABP166 using transmission electron microscopy. Fusion of each NLS resulted in shuttling of the cytoplasmic domain to the nucleus. With the exception of 2 domains, all of the evaluated domains localized within the nucleus. A mutation in the first block of bipartite signals affected the localization of the domains containing an NLS. The addition of an NES shifted the localization of these domains to the cytoplasm. The results presented here establish EhNCABP166 as a protein containing functional nuclear localization signals and a nuclear export signal.
Collapse
|
13
|
Host-parasite interaction: parasite-derived and -induced proteases that degrade human extracellular matrix. J Parasitol Res 2012; 2012:748206. [PMID: 22792442 PMCID: PMC3390111 DOI: 10.1155/2012/748206] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 05/07/2012] [Indexed: 12/29/2022] Open
Abstract
Parasitic protozoa are among the most important pathogens worldwide. Diseases such as malaria, leishmaniasis, amoebiasis, giardiasis, trichomoniasis, and trypanosomiasis affect millions of people. Humans are constantly threatened by infections caused by these pathogens. Parasites engage a plethora of surface and secreted molecules to attach to and enter mammalian cells. The secretion of lytic enzymes by parasites into host organs mediates critical interactions because of the invasion and destruction of interstitial tissues, enabling parasite migration to other sites within the hosts. Extracellular matrix is a complex, cross-linked structure that holds cells together in an organized assembly and that forms the basement membrane lining (basal lamina). The extracellular matrix represents a major barrier to parasites. Therefore, the evolution of mechanisms for connective-tissue degradation may be of great importance for parasite survival. Recent advances have been achieved in our understanding of the biochemistry and molecular biology of proteases from parasitic protozoa. The focus of this paper is to discuss the role of protozoan parasitic proteases in the degradation of host ECM proteins and the participation of these molecules as virulence factors. We divide the paper into two sections, extracellular and intracellular protozoa.
Collapse
|
14
|
Exposure to host ligands correlates with colocalization of Gal/GalNAc lectin subunits in lipid rafts and phosphatidylinositol (4,5)-bisphosphate signaling in Entamoeba histolytica. EUKARYOTIC CELL 2012; 11:743-51. [PMID: 22505337 DOI: 10.1128/ec.00054-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Entamoeba histolytica is an intestinal parasite that causes dysentery and liver abscess. Parasite cell surface receptors, such as the Gal/GalNAc lectin, facilitate attachment to host cells and extracellular matrix. The Gal/GalNAc lectin binds to galactose or N-acetylgalactosamine residues on host components and is composed of heavy (Hgl), intermediate (Igl), and light (Lgl) subunits. Although Igl is constitutively localized to lipid rafts (cholesterol-rich membrane domains), Hgl and Lgl transiently associate with this compartment in a cholesterol-dependent fashion. In this study, trophozoites were exposed to biologically relevant ligands to determine if ligand binding influences the submembrane distribution of the subunits. Exposure to human red blood cells (hRBCs) or collagen, which are bona fide Gal/GalNAc lectin ligands, was correlated with enrichment of Hgl and Lgl in rafts. This enrichment was abrogated in the presence of galactose, suggesting that direct lectin-ligand interactions are necessary to influence subunit location. Using a cell line that is able to attach to, but not phagocytose, hRBCs, it was shown that physical attachment to ligands was not sufficient to induce the enrichment of lectin subunits in rafts. Additionally, the mutant had lower levels of phosphatidylinositol (4,5)-bisphosphate (PIP(2)); PIP(2) loading restored the ability of this mutant to respond to ligands with enrichment of subunits in rafts. Finally, intracellular calcium levels increased upon attachment to collagen; this increase was essential for the enrichment of lectin subunits in rafts. Together, these data provide evidence that ligand-induced enrichment of lectin subunits in rafts may be the first step in a signaling pathway that involves both PIP(2) and calcium signaling.
Collapse
|
15
|
Molecular and functional characterization of an Entamoeba histolytica protein (EhMLCI) with features of a myosin essential light chain. Mol Biochem Parasitol 2012; 181:17-28. [DOI: 10.1016/j.molbiopara.2011.09.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 09/14/2011] [Accepted: 09/17/2011] [Indexed: 01/08/2023]
|
16
|
Campos-Parra A, Hernández-Cuevas N, Hernandez-Rivas R, Vargas M. EhNCABP166: A nucleocytoplasmic actin-binding protein from Entamoeba histolytica. Mol Biochem Parasitol 2010; 172:19-30. [DOI: 10.1016/j.molbiopara.2010.03.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 03/09/2010] [Accepted: 03/15/2010] [Indexed: 01/06/2023]
|
17
|
Affiliation(s)
- J P Ackers
- Department of Medical Parasitology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT
| |
Collapse
|
18
|
Chávez-Munguía B, Talamás-Rohana P, Ríos A, González-Lázaro M, Martínez-Palomo A. Entamoeba histolytica: Fibrilar aggregates in dividing trophozoites. Exp Parasitol 2008; 118:280-4. [PMID: 17870071 DOI: 10.1016/j.exppara.2007.08.001] [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] [Received: 04/19/2007] [Revised: 08/02/2007] [Accepted: 08/03/2007] [Indexed: 11/22/2022]
Abstract
Entamoeba histolytica trophozoite cytokinesis is dependent upon cytoskeletal elements such as filamentous actin and myosin. Here we present confocal and transmission electron microscopy studies of this process. A sequence in the formation of the contractile ring was shown with rhodamine-phalloidine staining. Ultrastructural analysis revealed the presence of fibrilar aggregates in the cytoplasm of dividing trophozoites. Among them two filaments of different diameter were identified. These aggregates presented repeating assemblies of thin and thick filaments that in cross section revealed a muscle-like appearance. Our results suggest that these aggregates constitute the contractile ring responsible for the separation of daughter cells.
Collapse
Affiliation(s)
- Bibiana Chávez-Munguía
- Department of Experimental Pathology, Center for Research and Advanced Studies, Av. IPN 2508, Zacatenco 07360, Mexico City, Mexico.
| | | | | | | | | |
Collapse
|
19
|
Smith SJ, McCann RO. A C-terminal dimerization motif is required for focal adhesion targeting of Talin1 and the interaction of the Talin1 I/LWEQ module with F-actin. Biochemistry 2007; 46:10886-98. [PMID: 17722883 DOI: 10.1021/bi700637a] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Focal adhesion complexes are plasma membrane-associated multicomponent complexes that are essential for integrin-linked signal transduction as well as cell adhesion and cell motility. The cytoskeletal protein Talin1 links integrin adhesion receptors with the actin cytoskeleton. Talin1 and the other animal and amoebozoan talins are members of the I/LWEQ module superfamily, which also includes fungal Sla2 and animal Hip1/Hip1R. The I/LWEQ module is a conserved C-terminal structural element that is critical for I/LWEQ module protein function. The I/LWEQ module of Talin1 binds to F-actin and targets the protein to focal adhesions in vivo. The I/LWEQ modules of Sla2 and Hip1 are required for the participation of these proteins in endocytosis. In addition to these roles in I/LWEQ module protein function, we have recently shown that the I/LWEQ module also contains a determinant for protein dimerization. Taken together, these results suggest that actin binding, subcellular targeting, and dimerization are associated in I/LWEQ module proteins. In this report we have used alanine-scanning mutagenesis of a putative coiled coil at the C-terminus of the Talin1 I/LWEQ module to show that the amino acids responsible for dimerization are necessary for F-actin binding, the stabilization of actin filaments, the cross-linking of actin filaments, and focal adhesion targeting. Our results suggest that this conserved dimerization motif in the I/LWEQ module plays an essential role in the function of Talin1 as a component of focal adhesions and, by extension, the other I/LWEQ module proteins in other multicomponent assemblies involved in cell adhesion and vesicle trafficking.
Collapse
Affiliation(s)
- Steven J Smith
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, 741 South Limestone Street, Lexington, Kentucky 40536-0509, USA
| | | |
Collapse
|
20
|
Arias-Romero LE, de Jesús Almáraz-Barrera M, Díaz-Valencia JD, Rojo-Domínguez A, Hernandez-Rivas R, Vargas M. EhPAK2, a novel p21-activated kinase, is required for collagen invasion and capping in Entamoeba histolytica. Mol Biochem Parasitol 2006; 149:17-26. [PMID: 16716419 DOI: 10.1016/j.molbiopara.2006.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Revised: 04/03/2006] [Accepted: 04/04/2006] [Indexed: 12/22/2022]
Abstract
p21-activated kinases (PAKs) are a highly conserved family of enzymes that are activated by Rho GTPases. All PAKs contain an N-terminal Cdc42/Rac interacting binding (CRIB) domain, which confers binding to these GTPases, and a C-terminal kinase domain. In addition, some PAKs such as Cla4p, Skm1p and Pak2p contain an N-terminal pleckstrin homology (PH) domain and form a distinct group of PAK proteins involved in cell morphology, cell-cycle and gene transcription. Here, we describe a novel p21-activated kinase, denominated EhPAK2, on the parasitic protozoan Entamoeba histolytica. This is the first reported Entamoeba PAK member that contains a N-terminal PH domain and a highly conserved CRIB domain. EhPAK2 CRIB domain shares 29% of amino acid identity and 53% of amino acid homology with these of DdPAKC from Dictyostelium discoideum and Cla4p from Saccharomyces cerevisiae and binds in vitro and in vivo to EhRacA GTPase. This domain also possesses the conserved residues His123, Phe134 and Trp141, which are important for the interaction with the effector loop and strand beta2 of the GTPase; and the residues Met121 and Phe145, which are specific for the interaction of EhPAK2 with EhRacA. Functional studies of EhPAK2 showed that its C-terminal kinase domain had activity toward myelin basic protein. Cellular studies showed that Entamoeba trophozoites transfected with the vector pExEhNeo/kinase-myc, had a 90% decrease in the ability to invade a collagen matrix as well as severe defects in capping, suggesting the involvement of EhPAK2 in these cellular processes.
Collapse
Affiliation(s)
- Luis Enrique Arias-Romero
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios, Avanzados del IPN, Mexico, DF, Mexico
| | | | | | | | | | | |
Collapse
|
21
|
Meza I, Talamás-Rohana P, Vargas MA. The Cytoskeleton of Entamoeba histolytica: Structure, Function, and Regulation by Signaling Pathways. Arch Med Res 2006; 37:234-43. [PMID: 16380324 DOI: 10.1016/j.arcmed.2005.09.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2005] [Accepted: 09/26/2005] [Indexed: 01/16/2023]
Abstract
Pathogenesis in the parasite Entamoeba histolytica has been related to motility of the trophozoites. Motility is an important feature in amebas as they perform multiple motile functions during invasion of host tissues. As motility depends on the organization and regulation of the cytoskeleton elements, in particular of the actin cytoskeleton, the study of the molecular components of the machinery responsible for movement has been a key aspect to study in this parasite. Although many of the components have high homology in amino acid sequence and function to those characterized in higher eukaryotic cells, there are important differences to suggest that parasitic organisms may have developed adaptative differences that could be useful as targets to stop invasion. The purpose of this review is to evaluate current knowledge about the cytoskeleton of E. histolytica and the ways in which the parasite controls motility.
Collapse
Affiliation(s)
- Isaura Meza
- Departamentos de Biomedicina Molecular, Centro de Investigación y de Estudios, Avanzados del IPN, México D.F., México.
| | | | | |
Collapse
|
22
|
Franco-Barraza J, Zamudio-Meza H, Franco E, del Carmen Domínguez-Robles M, Villegas-Sepúlveda N, Meza I. Rho signaling inEntamoeba histolytica modulates actomyosin-dependent activities stimulated during invasive behavior. ACTA ACUST UNITED AC 2006; 63:117-31. [PMID: 16421927 DOI: 10.1002/cm.20105] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Interaction of Entamoeba histolytica trophozoites with target cells and substrates activates signaling pathways in the parasite. Phosphorylation cascades triggered by phospho-inositide and adenyl-cyclase-dependent pathways modulate reorganization of the actin cytoskeleton to form structures that facilitate adhesion. In contrast, little is known about participation of Rho proteins and Rho signaling in actin rearrangements. We report here the in vivo expression of at least one Rho protein in trophozoites, whose activation induced actin reorganization and actin-myosin interaction. Antibodies to EhRhoA1 recombinant protein mainly localized Rho in the cytosol of nonactivated amoebae, but it was translocated to vesicular membranes and to some extent to the plasma membrane after treatment with lysophosphatidic acid (LPA), a specific agonist of Rho activation. Activated Rho was identified in LPA-treated trophozoites. LPA induced striking polymerization of actin into distinct dynamic structures. Disorganization of these structures by inhibition of Rho effector, Rho-kinase (ROCK), and by ML-7, an inhibitor of myosin light chain kinase dependent phosphorylation of myosin light chain, suggested that the actin structures also contained myosin. LPA stimulated concanavalin-A-mediated formation of caps, chemotaxis, invasion of extracellular matrix substrates, and erythrophagocytosis, but not binding to fibronectin. ROCK inhibition impaired LPA-stimulated functions and to some extent adhesion to fibronectin. Similar results were obtained with ML-7. These data suggest the presence and operation of Rho-signaling pathways in E. histolytica, that together with other, already described, signaling routes modulate actomyosin-dependent motile processes, particularly stimulated during invasive behavior.
Collapse
|
23
|
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.
Collapse
Affiliation(s)
- Ana Virel
- Biochemistry, Umeå University, SE-901 87 Umeå, Sweden
| | | |
Collapse
|
24
|
Rawal S, Majumdar S, Vohra H. Activation of MAPK kinase pathway by Gal/GalNAc adherence lectin of E. histolytica: gateway to host response. Mol Cell Biochem 2005; 268:93-101. [PMID: 15724442 DOI: 10.1007/s11010-005-3698-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Amoebiasis caused by the protozoan parasite Entamoeba histolytica is one of the leading parasitic causes of morbidity and mortality in the developing countries. Among the variety of virulence factors, an adherence lectin (Gal/GalNAc, 260 kDa) has been known to mediate colonization and subsequent host responses. It is a major cell surface antigen which is universally recognized by the immune sera of patients with amoebic liver abscess (ALA). The role of this lectin in cytolysis and phagocytosis of human colonic mucin glycoproteins has also been established. The objective of the present study was to elucidate the signal transduction events induced in response to Entamoeba histolytica derived Gal/GalNAc lectin in the target epithelial cells. We have attempted to define a pathway in target cells that could link this immunodominant antigen to a known biological pathway for target cell activation and triggering of subsequent disease pathology/parasite survival. Lectin stimulated cells showed immediate rise in (Ca2+)i concentration corresponding to 1517.31+/-16.3 nM (approximately) at 0-2 min. The intracellular calcium also extruded from the cells as was measured by increase in calcium green-1 fluorescence. Expression of several protein kinases was checked by western blotting to delineate the signaling pathway. Results showed that the expression of PLA2, PI3K, Ras p21, Ras GAP, ERK-MAPK, p38MAPK and PKC was significantly increased. Expression of Raf-1 and MEK-1 was also found to be significant, as determined by intensity analysis. Overall, it indicated activation of MAPKinase pathway which is implicated in a variety of cellular functions. On the basis of our observations it can be stated that there is a calcium mediated activation of PKC in target cells, by lectin, which inturn activates cyclic nucleotides and other protein kinases. These protein kinases further phosphorylated downstream signals in a sequential manner, thus leading to the activation of MAPKinase cascade. Activation of MAPK cascade, in our studies, is implicated in a variety of physiological cellular functions including apoptosis, proliferation, cytoskeleton rearrangements and permeability changes. However, future screening of the genes responsible for the transcription and translation of new proteins and their biological functions in response to lectin stimulation will prove useful in understanding this host-parasite relationship.
Collapse
Affiliation(s)
- Seema Rawal
- Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh-160 012, India
| | | | | |
Collapse
|
25
|
Mora-Galindo J, Anaya-Velázquez F, Ramírez-Romo S, González-Robles A. Entamoeba histolytica: correlation of assessment methods to measure erythrocyte digestion, and effect of cysteine proteinases inhibitors in HM-1:IMSS and HK-9:NIH strains. Exp Parasitol 2004; 108:89-100. [PMID: 15582505 DOI: 10.1016/j.exppara.2004.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Revised: 08/17/2004] [Accepted: 08/17/2004] [Indexed: 01/01/2023]
Abstract
Entamoeba histolytica trophozoites are able to degrade human erythrocytes; the loss of erythrocyte cellular matrix and degradation of plasma membrane were observed, along with the decrease in the average size of digestive vacuoles. Ninety-six percent of hemoglobin ingested was hydrolyzed by trophozoites within 3h, as evidenced by electrophoresis. Accordingly, X-ray spectroscopy revealed the presence of iron inside vacuoles after erythrophagocytosis, the concentration of which decreased to control levels in a similar period. Quantification of erythrocyte digestion at the early and late periods was determined by a spectrophotometric procedure, with t(1/2)=1.67 h and 35-min for HM-1:IMSS and HK-9:NIH trophozoites, respectively. In the latter, activity was due to the combined action of intracellular enzymatic activity and exocytosis. E-64c and leupeptin totally inhibited erythrocyte digestion within a 3-h period, thereafter hydrolysis took place at lower rate. Our results suggest that erythrocyte digestion in E. histolytica proceeds in different ways in these two amebic strains, and can be blocked by proteinase inhibitors.
Collapse
Affiliation(s)
- Juan Mora-Galindo
- Centro de Investigación Biomédica de Occidente-Instituto Mexicano del Seguro Social, Ap. Postal 1-3838, Guadalajara, Jal. 44100, Mexico.
| | | | | | | |
Collapse
|
26
|
Laughlin RC, McGugan GC, Powell RR, Welter BH, Temesvari LA. Involvement of raft-like plasma membrane domains of Entamoeba histolytica in pinocytosis and adhesion. Infect Immun 2004; 72:5349-57. [PMID: 15322032 PMCID: PMC517461 DOI: 10.1128/iai.72.9.5349-5357.2004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2004] [Accepted: 05/22/2004] [Indexed: 01/11/2023] Open
Abstract
Lipid rafts are highly ordered, cholesterol-rich, and detergent-resistant microdomains found in the plasma membrane of many eukaryotic cells. These domains play important roles in endocytosis, secretion, and adhesion in a variety of cell types. The parasitic protozoan Entamoeba histolytica, the causative agent of amoebic dysentery, was determined to have raft-like plasma membrane domains by use of fluorescent lipid analogs that specifically partition into raft and nonraft regions of the membrane. Disruption of raft-like membrane domains in Entamoeba with the cholesterol-binding agents filipin and methyl-beta-cyclodextrin resulted in the inhibition of several important virulence functions, fluid-phase pinocytosis, and adhesion to host cell monolayers. However, disruption of raft-like domains did not inhibit constitutive secretion of cysteine proteases, another important virulence function of Entamoeba. Flotation of the cold Triton X-100-insoluble portion of membranes on sucrose gradients revealed that the heavy, intermediate, and light subunits of the galactose-N-acetylgalactosamine-inhibitible lectin, an important cell surface adhesion molecule of Entamoeba, were enriched in cholesterol-rich (raft-like) fractions, whereas EhCP5, another cell surface molecule, was not enriched in these fractions. The subunits of the lectin were also observed in high-density, actin-rich fractions of the sucrose gradient. Together, these data suggest that pinocytosis and adhesion are raft-dependent functions in this pathogen. This is the first report describing the existence and physiological relevance of raft-like membrane domains in E. histolytica.
Collapse
Affiliation(s)
- Richard C Laughlin
- Department of Biological Sciences, Clemson University, 132 Long Hall, Clemson, SC 29634, USA
| | | | | | | | | |
Collapse
|
27
|
Manning-Cela R, Marquez C, Franco E, Talamas-Rohana P, Meza I. BFA-sensitive and insensitive exocytic pathways in Entamoeba histolytica trophozoites: their relationship to pathogenesis. Cell Microbiol 2003; 5:921-32. [PMID: 14641177 DOI: 10.1046/j.1462-5822.2003.00332.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Entamoeba histolytica manifests its pathogenicity through several cellular processes triggered by external stimuli that activate signal transduction pathways. The intense secretory activity resulting from stimulation is not correlated with a typical endoplasmic reticulum (ER) or Golgi organization, and little is known in this parasite about endocytic/exocytic pathways. The interactions of trophozoites with fibronectin (FN) and cultured mammalian cells, which elicit secretory activities, were chosen to study mechanisms that regulate cytoplamic traffic. Results showed that Brefeldin A (BFA) induced redistribution of the vesicular network recognized by antibodies against amoebic proteins PDI and ERD2. Furthermore, BFA diminished traffic to the plasma membrane of the beta1 integrin-like FN receptor and the heavy subunit of the Gal/GalNAc lectin, required for adhesion to FN and target cells, respectively. However, BFA did not prevent thiol-proteinase secretion or inhibit the traffic of de novo synthesized proteinases. These data suggest that two distinct transport systems occur in E. histolytica, one similar to classical membrane protein transport and another independent of BFA and inducible by external stimuli. Actin-myosin contractility of the cortical cytoskeleton seems necessary for the final release of exported proteinases and the proper function of the surface proteins involved in adhesion.
Collapse
Affiliation(s)
- Rebeca Manning-Cela
- Departamento de Biomedicina Molecular, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado 14-740, Mexico, DF 07000, Mexico.
| | | | | | | | | |
Collapse
|
28
|
Flores-Robles D, Rosales C, Rosales-Encina JL, Talamás-Rohana P. Entamoeba histolytica: a beta 1 integrin-like fibronectin receptor assembles a signaling complex similar to those of mammalian cells. Exp Parasitol 2003; 103:8-15. [PMID: 12810041 DOI: 10.1016/s0014-4894(03)00062-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
During tissue invasion, Entamoeba histolytica trophozoites interact with endothelial cells and extracellular matrix (ECM) proteins such as fibronectin (FN), collagen, and laminin. It has been demonstrated that trophozoites interact with FN through a beta1 integrin-like FN receptor (beta 1EhFNR), activating tyrosine kinases. In order to characterize the signaling process triggered by the amoebic receptor, activation, and association of tyrosine kinases and structural proteins were determined. As a result of FN binding by the beta 1EhFNR, the receptor itself, FAK, and paxillin were phosphorylated in tyrosine. Co-immunoprecipitation experiments showed that a multimolecular signaling complex was formed by the amoebic FN receptor, FAK, paxillin, and vinculin. These results strongly suggest that a signaling pathway, similar to the one used in mammalian cells, is activated when E. histolytica trophozoites adhere to FN.
Collapse
Affiliation(s)
- Donaciano Flores-Robles
- Department of Experimental Pathology, CINVESTAV-IPN, Ave. I.P.N. No. 2508, Col. San Pedro Zacatenco, 07360 México, D.F., México
| | | | | | | |
Collapse
|
29
|
Sengupta K, Hernández-Ramírez VI, Talamás-Rohana P. Monoclonal antibody specific to the beta1 integrin-like molecule (140 kDa) immunoprecipitates a protein complex of Entamoeba histolytica. Arch Med Res 2000; 31:S147-8. [PMID: 11070260 DOI: 10.1016/s0188-4409(00)00191-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- K Sengupta
- Departamento de Patología Experimental, Centro de Investigación y de Estudios Avanzados del I.P.N. (Cinvestav), Mexico City, Mexico
| | | | | |
Collapse
|
30
|
López LB, Braga MB, López JO, Arroyo R, Costa e Silva Filho F. Strategies by which some pathogenic trichomonads integrate diverse signals in the decision-making process. AN ACAD BRAS CIENC 2000; 72:173-86. [PMID: 10932116 DOI: 10.1590/s0001-37652000000200006] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The interaction between each one of Trichomonas vaginalis and Tritrichomonas foetus with their hosts is a complex process in which components associated to the cell surfaces of both parasites and host epithelial cells, and also to soluble components found in vaginal/urethral secretions, are involved. Either cytoadhesion or the cytotoxicity exerted by parasites to host cells can be dictated by virulence factors such as adhesins, cysteine proteinases, laminin-binding proteins, integrins, integrin-like molecules, a cell detachment factor, a pore-forming protein, and glycosidases among others. How trichomonads manipulate informations from the extracellular medium, transduce such informations, and respond to them by stimulating the activities of some surface molecules and/or releasing enzymes are the aspects concerning trichomonal virulence which are here briefly reviewed and discussed.
Collapse
Affiliation(s)
- L B López
- UFRJ-Instituto de Biofísica Carlos Chagas Filho, Rio de Janeiro, Brazil
| | | | | | | | | |
Collapse
|
31
|
Hernández-Ramírez VI, Anaya-Ruiz M, Rios A, Talamás-Rohana P. Entamoeba histolytica: tyrosine kinase activity induced by fibronectin through the beta1-integrin-like molecule. Exp Parasitol 2000; 95:85-95. [PMID: 10910709 DOI: 10.1006/expr.2000.4522] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previously, we characterized a 140-kDa protein from Entamoeba histolytica as a beta1-integrin-like molecule that binds fibronectin. In this work we present data showing that the amoebic receptor is associated with another surface molecule, the 220-kDa lectin, and with protein tyrosine kinase activity. By immunoprecipitation with the alphabeta1Eh antibody, we demonstrated by immune complex assays for tyrosine protein kinases that the amoebic fibronectin receptor was associated with two phosphorylated proteins of 50 and 70 kDa when internal membranes were used as the source of antigen. When cells were stimulated with fibronectin, two proteins of 55 and 90 kDa were tyrosine phosphorylated, as shown by Western blot with alphaPY20, its phosphorylation being time dependent after fibronectin stimulation. However, when the actin cytoskeleton of fibronectin-stimulated trophozoites was stabilized with phalloidin, the level and the pattern of phosphorylated proteins were different. In this case, a high-molecular-weight component, heavily phosphorylated, was present, which may include the 220-kDa lectin. We also present data confirming that the signaling pathway that is activated by fibronectin is specific. This was demonstrated by comparing the pattern of phosphoproteins obtained in immune complexes prepared with alphabeta1Eh, alphaL220, and alphaPY20 from total extracts obtained in the presence of phalloidin, from cells that had been exposed to fibronectin, soluble concanavalin A, or concanavalin-A-coated substrate. The presence of tyrosine kinases associated with the beta1-integrin-like amoebic molecule was confirmed by immunoprecipitation assays along with the combined use of a tyrosine kinase-specific substrate, the peptide RR-SRC, and a tyrosine kinase inhibitor, genistein.
Collapse
Affiliation(s)
- V I Hernández-Ramírez
- Experimental Pathology Department, CINVESTAV-IPN, Avenida I.P.N. No. 2508, Col. San Pedro Zacatenco, México, DF 07360, México
| | | | | | | |
Collapse
|
32
|
Abstract
Amebiasis is a major cause of morbidity and mortality throughout the tropical world. Entamoeba histolytica is now recognized as a separate species from the morphologically identical E. dispar, which cannot invade. Cysteine proteinases are a key virulence factor of E. histolytica and play a role in intestinal invasion by degrading the extracellular matrix and circumventing the host immune response through cleavage of secretory immunoglobulin A (sIgA), IgG, and activation of complement. Cysteine proteinases are encoded by at least seven genes, several of which are found in E. histolytica but not E. dispar. A number of new animal models, including the formation of liver abscesses in SCID mice and intestinal infection in human intestinal xenografts, have proven useful to confirm the critical role of cysteine proteinases in invasion. Detailed structural analysis of cysteine proteinases should provide further insights into their biochemical function and may facilitate the design of specific inhibitors which could be used as potential chemotherapeutic agents in the future.
Collapse
|
33
|
Abstract
In spite of a wealth of knowledge on the biochemistry and cellular and molecular biology of Entamoeba histolytica, little has been done to apply these advances to our understanding of the lesions observed in patients with intestinal amebiasis. In this review, the pathological and histological findings in acute amebic colitis are related to the molecular mechanisms of E. histolytica pathogenicity described to date. Infection of the human colon by E. histolytica produces focal ulceration of the intestinal mucosa, resulting in dysentery (diarrhea with blood and mucus). Although a complete picture has not yet been achieved, the basic mechanisms involved in the production of focal lytic lesions include complex multifactorial processes in which lectins facilitate adhesion, proteases degrade extracellular matrix components, porins help nourish the parasite and may also kill incoming polymorphonuclear leukocytes and macrophages, and motility is used by the parasite to invade deeper layers of the colon. In addition, E. histolytica has developed mechanisms to modulate the immune response during acute infection. Nevertheless, much still needs to be unraveled to understand how this microscopic parasite has earned its well-deserved histolytic name.
Collapse
|
34
|
Abstract
Amebiasis is a major cause of morbidity and mortality throughout the tropical world. Entamoeba histolytica is now recognized as a separate species from the morphologically identical E. dispar, which cannot invade. Cysteine proteinases are a key virulence factor of E. histolytica and play a role in intestinal invasion by degrading the extracellular matrix and circumventing the host immune response through cleavage of secretory immunoglobulin A (sIgA), IgG, and activation of complement. Cysteine proteinases are encoded by at least seven genes, several of which are found in E. histolytica but not E. dispar. A number of new animal models, including the formation of liver abscesses in SCID mice and intestinal infection in human intestinal xenografts, have proven useful to confirm the critical role of cysteine proteinases in invasion. Detailed structural analysis of cysteine proteinases should provide further insights into their biochemical function and may facilitate the design of specific inhibitors which could be used as potential chemotherapeutic agents in the future.
Collapse
Affiliation(s)
- X Que
- Departments of Pathology and Medicine, University of California San Diego Medical Center, San Diego, CA 92103-8416, USA
| | | |
Collapse
|
35
|
Espinosa-Cantellano M, Martínez-Palomo A. Pathogenesis of intestinal amebiasis: from molecules to disease. Clin Microbiol Rev 2000; 13:318-31. [PMID: 10756002 PMCID: PMC100155 DOI: 10.1128/cmr.13.2.318] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In spite of a wealth of knowledge on the biochemistry and cellular and molecular biology of Entamoeba histolytica, little has been done to apply these advances to our understanding of the lesions observed in patients with intestinal amebiasis. In this review, the pathological and histological findings in acute amebic colitis are related to the molecular mechanisms of E. histolytica pathogenicity described to date. Infection of the human colon by E. histolytica produces focal ulceration of the intestinal mucosa, resulting in dysentery (diarrhea with blood and mucus). Although a complete picture has not yet been achieved, the basic mechanisms involved in the production of focal lytic lesions include complex multifactorial processes in which lectins facilitate adhesion, proteases degrade extracellular matrix components, porins help nourish the parasite and may also kill incoming polymorphonuclear leukocytes and macrophages, and motility is used by the parasite to invade deeper layers of the colon. In addition, E. histolytica has developed mechanisms to modulate the immune response during acute infection. Nevertheless, much still needs to be unraveled to understand how this microscopic parasite has earned its well-deserved histolytic name.
Collapse
|
36
|
Meza I. Extracellular matrix-induced signaling in Entamoeba histolytica: its role in invasiveness. PARASITOLOGY TODAY (PERSONAL ED.) 2000; 16:23-8. [PMID: 10637584 DOI: 10.1016/s0169-4758(99)01586-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Entamoeba histolytica trophozoites can invade the mucosa of the host large intestine to cause disease. Here, Isaura Meza describes recent work indicating that the trophozoites respond to the binding of extracellular matrix proteins by activating receptor-mediated signal transduction pathways. Activation of phosphokinase C or adenylyl cyclase induces protein phosphorylation, actin gene expression and reorganization of the actin cytoskeleton to form adhesive structures that promote interaction with the substrate and the release of proteases. The release of proteases at the sites of contact, with the subsequent degradation of the substrate and generation of chemotactic peptides, facilitates locomotion and dissemination of the invading trophozoites.
Collapse
Affiliation(s)
- I Meza
- Departamento de Biomedicina Molecular, CINVESTAV del IPN, México, D.F., México.
| |
Collapse
|
37
|
Soid-Raggi LG, Torres-Márquez ME, Meza I. Entamoeba histolytica: identification of functional Gs and Gi proteins as possible signal transduction elements in the interaction of trophozoites with fibronectin. Exp Parasitol 1998; 90:262-9. [PMID: 9806871 DOI: 10.1006/expr.1998.4333] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Trophozoites of Entamoeba histolytica adhere to several components of the extracellular matrix. Binding is mediated by specific receptors identified in the parasite surface. Interaction of trophozoites with FN induces the formation of special adhesion structures that are dynamic cytoskeleton membrane complexes and facilitate both adhesion and substrate degradation. The process requires activation of signaling pathways in which PLC, IP3, Ca2-, and PKC participate. These observations, and recent experiments showing increments in cAMP in the trophozoites during the interaction with FN, suggest that FN receptors in the amebic surface could be coupled to G-proteins. We report here that trophozoite plasma membrane peptides of 92, 49, 42, 37, and 21 kDa are ADP-ribosylated by Vibrio cholerae and Bordetella pertussis toxins. Three of them are also recognized by antibodies prepared against the alpha-subunit of Gs-and Gi-proteins. Adenylyl cyclase activity detected in isolated membranes was strongly stimulated by treatment with the toxins. Forskolin (an agonist of the enzyme) and FN also induced increments in the enzymatic activity. Live amebas incubated with the toxins showed enhanced adhesion to FN substrates and a striking reorganization of polymerized actin. The actin rearrangement is reminiscent of the one induced by either forskolin or dibutyril cyclic AMP treatment. Our present data show the presence and the functionality of Gs- and Gi-like proteins and their apparent activation during in vitro interaction of amebas with FN and complement previous observations indicating the operation of signal transduction mechanisms in E. histolytica.
Collapse
Affiliation(s)
- L G Soid-Raggi
- Departamento de Biología Celular, CINVESTAV del IPN, México, D.F., México
| | | | | |
Collapse
|
38
|
Venkataraman C, Gao LY, Bondada S, Kwaik YA. Identification of putative cytoskeletal protein homologues in the protozoan host Hartmannella vermiformis as substrates for induced tyrosine phosphatase activity upon attachment to the Legionnaires' disease bacterium, Legionella pneumophila. J Exp Med 1998; 188:505-14. [PMID: 9687528 PMCID: PMC2212481 DOI: 10.1084/jem.188.3.505] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The Legionnaires' disease bacterium, Legionella pneumophila, is a facultative intracellular pathogen that invades and replicates within two evolutionarily distant hosts, free living protozoa and mammalian cells. Invasion and intracellular replication within protozoa are thought to be major factors in the transmission of Legionnaires' disease. We have recently reported the identification of a galactose/N-acetyl-D-galactosamine (Gal/GalNAc) lectin in the protozoan host Hartmannella vermiformis as a receptor for attachment and invasion by L. pneumophila (Venkataraman, C., B.J. Haack, S. Bondada, and Y.A. Kwaik. 1997. J. Exp. Med. 186:537-547). In this report, we extended our studies to the effects of bacterial attachment and invasion on the cytoskeletal proteins of H. vermiformis. We first identified the presence of many protozoan cytoskeletal proteins that were putative homologues to their mammalian counterparts, including actin, pp125(FAK), paxillin, and vinculin, all of which were basally tyrosine phosphorylated in resting H. vermiformis. In addition to L. pneumophila-induced tyrosine dephosphorylation of the lectin, bacterial attachment and invasion was associated with tyrosine dephosphorylation of paxillin, pp125(FAK), and vinculin, whereas actin was minimally affected. Inhibition of bacterial attachment to H. vermiformis by Gal or GalNAc monomers blocked bacteria-induced tyrosine dephosphorylation of detergent-insoluble proteins. In contrast, inhibition of bacterial invasion but not attachment failed to block bacteria-induced tyrosine dephosphorylation of H. vermiformis proteins. This was further supported by the observation that 10 mutants of L. pneumophila that were defective in invasion of H. vermiformis were capable of inducing tyrosine dephosphorylation of H. vermiformis proteins. Entry of L. pneumophila into H. vermiformis was predominantly mediated by noncoated receptor-mediated endocytosis (93%) but coiling phagocytosis was infrequently observed (7%). We conclude that attachment but not invasion by L. pneumophila into H. vermiformis was sufficient and essential to induce protein tyrosine dephosphorylation in H. vermiformis. These manipulations of host cell processes were associated with, or followed by, entry of the bacteria by a noncoated receptor-mediated endocytosis. A model for attachment and entry of L. pneumophila into H. vermiformis is proposed.
Collapse
Affiliation(s)
- C Venkataraman
- Department of Microbiology and Immunology, University of Kentucky Chandler Medical Center, Lexington, Kentucky 40536-0084, USA
| | | | | | | |
Collapse
|
39
|
Godbold GD, Mann BJ. Involvement of the actin cytoskeleton and p21rho-family GTPases in the pathogenesis of the human protozoan parasite Entamoeba histolytica. Braz J Med Biol Res 1998; 31:1049-58. [PMID: 9777011 DOI: 10.1590/s0100-879x1998000800004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It has been estimated that infection with the enteric protozoan parasite Entamoeba histolytica kills more than 50,000 people a year. Central to the pathogenesis of this organism is its ability to directly lyse host cells and cause tissue destruction. Amebic lesions show evidence of cell lysis, tissue necrosis, and damage to the extracellular matrix. The specific molecular mechanisms by which these events are initiated, transmitted, and effected are just beginning to be uncovered. In this article we review what is known about host cell adherence and contact-dependent cytolysis. We cover the involvement of the actin cytoskeleton and small GTP-binding proteins of the p21rho-family in the process of cell killing and phagocytosis, and also look at how amebic interactions with molecules of the extracellular matrix contribute to its cytopathic effects.
Collapse
Affiliation(s)
- G D Godbold
- University of Virginia Health Sciences Center, Charlottesville 22908, USA
| | | |
Collapse
|
40
|
Guillén N, Boquet P, Sansonetti P. The small GTP-binding protein RacG regulates uroid formation in the protozoan parasite Entamoeba histolytica. J Cell Sci 1998; 111 ( Pt 12):1729-39. [PMID: 9601102 DOI: 10.1242/jcs.111.12.1729] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Entamoeba histolytica is a protozoan parasite that invades human intestine leading to ulceration and destruction of tissue. Amoebic movement and phagocytosis of human cells is accompanied by characteristic changes in cell morphology. Amoebae become polarized, developing a frontal pseudopod and a well-defined rear zone of membrane accumulation designated the uroid. In motile eukaryotic cells, a phenomenon that contributes to movement is the capping of receptors at the cell surface. During the capping process, E. histolytica concentrates ligand-receptor complexes in the uroid. Interestingly, some of these surface receptors are involved in the survival of the parasite. While looking for regulators of capping and uroid formation, we identified RacG, an E. histolytica protein that is homologous to human Rac1. This protein belongs to the Rac subfamily of small GTPases implicated in interactions between the actin cytoskeleton and the membrane of mammalian cells. Cloning of the EhracG gene and analysis of the protein activity either in murine fibroblasts or in E. histolytica revealed that EhRacG induces a characteristic Rac phenotype. When expressed in amoebae, an EhRacG-V12 mutant protein not only deregulated cell polarity, but also caused a defect in cytokinesis. Analysis of the cytoskeleton in amoebae bearing this mutant revealed that F-actin concentrated at the periphery of the cell. In addition, the number and localization of uroids were modified. These results suggest a role for EhRacG in amoebic morphogenesis and cytokinesis.
Collapse
Affiliation(s)
- N Guillén
- Unité de Pathogénie Microbienne Moléculaire, Institut National de la Santé et de la Recherche Médicale U389 Institut Pasteur, France.
| | | | | |
Collapse
|
41
|
Pérez E, Muñoz ML, Ortega A. Entamoeba histolytica: collagen-induced AP-1 DNA binding activity. FEMS Microbiol Lett 1998; 159:187-92. [PMID: 9580078 DOI: 10.1111/j.1574-6968.1998.tb12859.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The interaction of Entamoeba histolytica trophozoites with collagen induces the synthesis and release of electron-dense granules containing a collagenase activity that is an important factor in the pathogenicity of the parasite. The binding is thought to be mediated by an 'integrin-like' collagen receptor. In the signal transduction mechanisms activated by collagen, pp125FAK and p42MAPK are involved. Using immunoprecipitation assays coupled to Western blot analysis, we demonstrate here the collagen-dependent association of paxillin and Src with pp125FAK. Furthermore, collagen induces a time-dependent increase in the DNA binding activity of the activator protein 1, which is well correlated with an increase in Fos expression. Our results suggest that a stimulus-transcription coupling triggered by collagen in E. histolytica trophozoites might activate or repress genes involved in tissue invasiveness.
Collapse
Affiliation(s)
- E Pérez
- Departamento de Genética y Biologia Molecular, CINVESTAV-IPN, México DF, Mexico
| | | | | |
Collapse
|
42
|
|
43
|
Guillén N. Role of signalling and cytoskeletal rearrangements in the pathogenesis of Entamoeba histolytica. Trends Microbiol 1996; 4:191-7. [PMID: 8727599 DOI: 10.1016/0966-842x(96)10033-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Virulence of Entamoeba histolytica is characterized by intestinal tissue invasion, engulfment of host cells and the formation of liver abscesses. The actin-rich cytoskeleton of the amoeba allows rapid changes in morphology in response to signals from external stimuli. Cellular and molecular studies have described some of the proteins that participate in signalling and in cytoskeletal changes.
Collapse
Affiliation(s)
- N Guillén
- Unité de Pathogénie Microbienne Moléculaire, INSERM U389, Institut Pasteur, Paris, France.
| |
Collapse
|