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Benchimol M, Gadelha AP, de Souza W. Unusual Cell Structures and Organelles in Giardia intestinalis and Trichomonas vaginalis Are Potential Drug Targets. Microorganisms 2022; 10:2176. [PMID: 36363768 PMCID: PMC9698047 DOI: 10.3390/microorganisms10112176] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 10/28/2022] [Accepted: 10/31/2022] [Indexed: 09/29/2023] Open
Abstract
This review presents the main cell organelles and structures of two important protist parasites, Giardia intestinalis, and Trichomonas vaginalis; many are unusual and are not found in other eukaryotic cells, thus could be good candidates for new drug targets aimed at improvement of the chemotherapy of diseases caused by these eukaryotic protists. For example, in Giardia, the ventral disc is a specific structure to this parasite and is fundamental for the adhesion and pathogenicity to the host. In Trichomonas, the hydrogenosome, a double membrane-bounded organelle that produces ATP, also can be a good target. Other structures include mitosomes, ribosomes, and proteasomes. Metronidazole is the most frequent compound used to kill many anaerobic organisms, including Giardia and Trichomonas. It enters the cell by passive diffusion and needs to find a highly reductive environment to be reduced to the nitro radicals to be active. However, it provokes several side effects, and some strains present metronidazole resistance. Therefore, to improve the quality of the chemotherapy against parasitic protozoa is important to invest in the development of highly specific compounds that interfere with key steps of essential metabolic pathways or in the functional macromolecular complexes which are most often associated with cell structures and organelles.
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Affiliation(s)
- Marlene Benchimol
- Laboratorio de Ultraestrutura Celular Hertha Meyer, Centro de Ciêcias da Saúde, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Cidade Universitaria, Rio de Janeiro 96200-000, Brazil
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
- Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens e Centro Nacional de Biologia Estrutural e Bioimagens, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
| | - Ana Paula Gadelha
- Diretoria de Metrologia Aplicada as Ciências da Vida, Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMETRO), Rio de Janeiro 25250-020, Brazil
| | - Wanderley de Souza
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
- Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens e Centro Nacional de Biologia Estrutural e Bioimagens, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
- CMABio, Escola Superior de Saúde, Universidade do Estado do Amazonas-UEA, Manaus 69850-000, Brazil
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2
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Benchimol M, de Souza W. Giardia intestinalis and its Endomembrane System. J Eukaryot Microbiol 2022; 69:e12893. [PMID: 35148450 DOI: 10.1111/jeu.12893] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 02/08/2022] [Accepted: 02/08/2022] [Indexed: 11/29/2022]
Abstract
Giardia intestinalis has unique characteristics, even in the absence of certain organelles. For instance, Golgi and mitochondria are not found. On the other hand, there is a network of peripheral vacuoles (PVs) and mitosomes. The endoplasmic reticulum (ER), nuclear membrane, peroxisomes, and lipid bodies are present. The peripheral vacuole system seems to play several simultaneous roles. It is involved in the endocytic activity of the trophozoite but also has characteristics of early and late endosomes and even lysosomes, establishing a connection with the ER. Some of the PVs contain small vesicles, acting as multivesicular bodies, including the release of exosomes. The mitosomes are surrounded by two membranes, divide during mitosis, and are distributed throughout the cell. They do not contain DNA, enzymes involved in the citric acid cycle, respiratory chain, or ATP synthesis. However, they contain the iron-sulfur complex and transporters as TOM and TIM. Some mitosomes are linked to flagellar axonemes through a fibrillar connection. During encystation, two types of larger cytoplasmic vesicles appear. One originating from the ER contains the cyst wall proteins. Another contains carbohydrates. Both migrate to the cell periphery and fuse with plasma membrane secreting their contents to give rise to the cell wall.
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Affiliation(s)
- Marlene Benchimol
- Universidade do Grande Rio (UNIGRANRIO), Rio de Janeiro Duque de Caxias, RJ, Brazil.,Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.,Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Centro Nacional de Biologia Estrutural e Bioimagens, CENABIO-Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Wanderley de Souza
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.,Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Centro Nacional de Biologia Estrutural e Bioimagens, CENABIO-Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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3
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Benchimol M. Giardia intestinalis can interact, change its shape and internalize large particles and microorganisms. Parasitology 2021; 148:500-510. [PMID: 33280628 PMCID: PMC11010223 DOI: 10.1017/s0031182020002292] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 10/05/2020] [Accepted: 11/25/2020] [Indexed: 11/06/2022]
Abstract
Giardia intestinalis is a parasitic protozoan that inhabits its vertebrate hosts' upper small intestine and is the most common cause of waterborne diarrhoea worldwide. Giardia trophozoites present few organelles, and among them, they possess peripheral vesicles (PVs), which are considered an endosomal-lysosomal system. All experimental procedures carried out until now indicate that Giardia ingests macromolecules by fluid-phase and receptor-mediated endocytic pathways. Still, there is no description concerning the interaction and ingestion of large materials. Here, we tested Giardia's capacity to interact with large particles; once, in vivo, it inhabits an environment with a microbiota. We tested protozoan interaction with yeasts, bacteria, latex beads, ferritin and albumin, in different times of interaction and used several microscopy techniques (light microscopy, scanning electron microscopy and transmission electron microscopy) to follow their fate. Giardia interacted with all of the materials we tested. Projections of the plasma membrane similar to pseudopods were seen. As albumin, small markers were found in the PVs while the larger materials were not seen there. Large vacuoles containing large latex beads were detected intracellularly. Thus, we observed that: (1) Giardia interacts with large materials; (2) Giardia can display an amoeboid shape and exhibit membrane projections when in contact with microorganisms and large inorganic materials; (3) the region of the exit of the ventral flagella is very active when in contact with large materials, although all cell surface also present activity in the interactions; (4) intracellular vacuoles, which are not the PVs, present ingested large beads.
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Affiliation(s)
- Marlene Benchimol
- UNIGRANRIO-Universidade do Grande Rio-Duque de Caxias-Rio de Janeiro, Rio de Janeiro, Brazil
- UFRJ-Universidade Federal do Rio de Janeiro-Instituto de Biofísica Carlos Chagas Filho-Laboratório de Ultraestrutura Celular Hertha Meyer, and Instituto Nacional de Ciência e Tecnologia-INBEB, Centro Nacional de Biologia Estrutural e Bioimagens-CENABIO, Rio de Janeiro, Brazil
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4
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Zamponi N, Zamponi E, Mayol GF, Lanfredi-Rangel A, Svärd SG, Touz MC. Endoplasmic reticulum is the sorting core facility in the Golgi-lacking protozoanGiardia lamblia. Traffic 2017; 18:604-621. [DOI: 10.1111/tra.12501] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 07/02/2017] [Accepted: 07/06/2017] [Indexed: 01/13/2023]
Affiliation(s)
- Nahuel Zamponi
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC - CONICET; Universidad Nacional de Córdoba; Córdoba Argentina
| | - Emiliano Zamponi
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC - CONICET; Universidad Nacional de Córdoba; Córdoba Argentina
| | - Gonzalo F. Mayol
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC - CONICET; Universidad Nacional de Córdoba; Córdoba Argentina
| | | | - Staffan G. Svärd
- Department of Cell and Molecular Biology; Uppsala University; Uppsala Sweden
| | - María C. Touz
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC - CONICET; Universidad Nacional de Córdoba; Córdoba Argentina
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5
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Touz MC, Zamponi N. Sorting without a Golgi complex. Traffic 2017; 18:637-645. [DOI: 10.1111/tra.12500] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 07/01/2017] [Accepted: 07/06/2017] [Indexed: 12/22/2022]
Affiliation(s)
- Maria C. Touz
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC - CONICET; Universidad Nacional de Córdoba; Córdoba Argentina
| | - Nahuel Zamponi
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC - CONICET; Universidad Nacional de Córdoba; Córdoba Argentina
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6
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Robles-Martinez L, Mendez TL, Apodaca J, Das S. Glucosylceramide transferase in Giardia preferentially catalyzes the synthesis of galactosylceramide during encystation. Mol Biochem Parasitol 2016; 211:75-83. [PMID: 27840079 DOI: 10.1016/j.molbiopara.2016.11.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 11/06/2016] [Accepted: 11/09/2016] [Indexed: 11/27/2022]
Abstract
The stage differentiation from trophozoite to cyst (i.e., encystation) is an essential step for Giardia to survive outside its human host and spread the infection via the fecal-oral route. We have previously shown that Giardia expresses glucosylceramide transferase 1 (GlcT1) enzyme, the activity of which is elevated during encystation. We have also reported that blocking the activity of gGlcT1 interferes with the biogenesis of encystation-specific vesicles (ESVs) and cyst viability in Giardia. To further understand the role of this enzyme and how it regulates encystation, we overexpressed, knocked down, and rescued the giardial GlcT1 (gGlcT1) gene and measured its enzymatic activity in live parasites as well as in isolated membrane fractions using NBD-ceramide and UDP-glucose or UDP-galactose. We observed that gGlcT1 is able to catalyze the synthesis of both glucosylceramide (GlcCer) and galactosylceramide (GalCer), however the synthesis of GalCer is 2-3 fold higher than of GlcCer. Although both activities follow Michaelis-Menten kinetics, the bindings of UDP-glucose and UDP-galactose with the enzyme appear to be non-competitive and independent of each other. The modulation of gGlcT1 synthesis concomitantly influenced the expression cyst-wall protein (CWP) and overall encystation. We propose that gGlcT1 is a unique enzyme and that Giardia uses this enzyme to synthesize both GlcCer and GalCer to facilitate the process of encystation/cyst production.
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Affiliation(s)
- Leobarda Robles-Martinez
- Infectious Disease and Immunology Cluster, Border Biomedical Research Center (BBRC), University of Texas at El Paso, El Paso, TX 79968-0519, USA; Department of Biological Sciences, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968-0519/USA, Tel: (915) 747-6896∥.,Department of Biological Sciences, University of Texas at El Paso, El Paso, TX 79968-0519, USA; Department of Biological Sciences, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968-0519/USA, Tel: (915) 747-6896∥
| | - Tavis L Mendez
- Infectious Disease and Immunology Cluster, Border Biomedical Research Center (BBRC), University of Texas at El Paso, El Paso, TX 79968-0519, USA; Department of Biological Sciences, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968-0519/USA, Tel: (915) 747-6896∥.,Department of Biological Sciences, University of Texas at El Paso, El Paso, TX 79968-0519, USA; Department of Biological Sciences, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968-0519/USA, Tel: (915) 747-6896∥
| | - Jennifer Apodaca
- Infectious Disease and Immunology Cluster, Border Biomedical Research Center (BBRC), University of Texas at El Paso, El Paso, TX 79968-0519, USA; Department of Biological Sciences, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968-0519/USA, Tel: (915) 747-6896∥.,Department of Biological Sciences, University of Texas at El Paso, El Paso, TX 79968-0519, USA; Department of Biological Sciences, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968-0519/USA, Tel: (915) 747-6896∥
| | - Siddhartha Das
- Infectious Disease and Immunology Cluster, Border Biomedical Research Center (BBRC), University of Texas at El Paso, El Paso, TX 79968-0519, USA; Department of Biological Sciences, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968-0519/USA, Tel: (915) 747-6896∥.,Department of Biological Sciences, University of Texas at El Paso, El Paso, TX 79968-0519, USA; Department of Biological Sciences, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968-0519/USA, Tel: (915) 747-6896∥
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7
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Sphingolipids, Lipid Rafts, and Giardial Encystation: The Show Must Go On. CURRENT TROPICAL MEDICINE REPORTS 2015; 2:136-143. [PMID: 26587369 DOI: 10.1007/s40475-015-0052-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Sphingolipids are sphingosine-based phospholipids, which are present in the plasma and endomembranes of many eukaryotic cells. These lipids are involved in various cellular functions, including cell growth, differentiation, and apoptosis. In addition, sphingolipid and cholesterol-enriched membrane microdomains (also called "lipid rafts") contain a set of proteins and lipids, which take part in the signaling process in response to intra- or extracellular stimuli. Recent findings suggest that sphingolipids, especially glucosylceramide, play a critical role in inducing encystation and maintaining the cyst viability in Giardia. Similarly, the assembly/disassembly of lipid rafts modulates the encystation and cyst production of this ubiquitous enteric parasite. In this review article, we discuss the overall progress in the field and examine whether sphingolipids and lipid rafts can be used as novel targets for designing therapies to control infection by Giardia, which is rampant in developing countries, where children are especially vulnerable.
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8
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Faso C, Hehl AB. Membrane trafficking and organelle biogenesis in Giardia lamblia: use it or lose it. Int J Parasitol 2011; 41:471-80. [PMID: 21296082 DOI: 10.1016/j.ijpara.2010.12.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 12/23/2010] [Accepted: 12/24/2010] [Indexed: 01/06/2023]
Abstract
The secretory transport capacity of Giardia trophozoites is perfectly adapted to the changing environment in the small intestine of the host and is able to deploy essential protective surface coats as well as molecules which act on epithelia. These lumen-dwelling parasites take up nutrients by bulk endocytosis through peripheral vesicles or by receptor-mediated transport. The environmentally-resistant cyst form is quiescent but poised for activation following stomach passage. Its versatility and fidelity notwithstanding, the giardial trafficking systems appear to be the product of a general secondary reduction process geared towards minimization of all components and machineries identified to date. Since membrane transport is directly linked to organelle biogenesis and maintenance, less complexity also means loss of organelle structures and functions. A case in point is the Golgi apparatus which is missing as a steady-state organelle system. Only a few basic Golgi functions have been experimentally demonstrated in trophozoites undergoing encystation. Similarly, mitochondrial remnants have reached a terminally minimized state and appear to be functionally restricted to essential iron-sulfur protein maturation processes. Giardia's minimized organization combined with its genetic tractability provides unique opportunities to study basic principles of secretory transport in an uncluttered cellular environment. Not surprisingly, Giardia is gaining increasing attention as a model for the investigation of gene regulation, organelle biogenesis, and export of simple but highly protective cell wall biopolymers, a hallmark of all perorally transmitted protozoan and metazoan parasites.
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Affiliation(s)
- Carmen Faso
- Institute of Parasitology, University of Zurich, Winterthurerstrasse 266a, 8057 Zurich, Switzerland
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9
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Cardiolipin, a lipid found in mitochondria, hydrogenosomes and bacteria was not detected in Giardia lamblia. Exp Parasitol 2008; 120:215-20. [DOI: 10.1016/j.exppara.2008.07.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2007] [Revised: 06/22/2008] [Accepted: 07/16/2008] [Indexed: 11/23/2022]
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10
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Maia C, Attias M, Urbina J, Gilbert I, Magaraci F, de Souza W. Azasterols impair Giardia lamblia proliferation and induces encystation. Biochem Biophys Res Commun 2007; 363:310-6. [PMID: 17870055 DOI: 10.1016/j.bbrc.2007.08.174] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Accepted: 08/23/2007] [Indexed: 01/22/2023]
Abstract
The effects of sterol biosynthesis inhibitors on growth and fine structure of Giardia lamblia P1 strain cultures were analyzed. Azasterols demonstrated high efficacy in killing cells. The IC(50) values for 22,26-azasterol and 24(R,S),25-epiminolanosterol were 7muM and 170nM, respectively. Morphological analysis showed that azasterols induced changes in G. lamblia ultrastructure. The most significant alterations were: (a) considerable increase of the size of the peripheral vesicles, which are part of the parasite endosomal-lysosomal system; (b) appearance of autophagosomal structures; and (c) induction of differentiation, followed by an abnormal enlargement of encystation secretory vesicles. We propose that azasterols are effective chemotherapeutic drugs against Giardia lamblia in vitro and may have another target in cells besides sterol biosynthesis.
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Affiliation(s)
- Claudia Maia
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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11
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Hernandez Y, Castillo C, Roychowdhury S, Hehl A, Aley SB, Das S. Clathrin-dependent pathways and the cytoskeleton network are involved in ceramide endocytosis by a parasitic protozoan, Giardia lamblia. Int J Parasitol 2007; 37:21-32. [PMID: 17087963 PMCID: PMC1831817 DOI: 10.1016/j.ijpara.2006.09.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2006] [Revised: 09/07/2006] [Accepted: 09/11/2006] [Indexed: 11/16/2022]
Abstract
Although identified as an early-diverged protozoan, Giardia lamblia shares many similarities with higher eukaryotic cells, including an internal membrane system and cytoskeleton, as well as secretory pathways. However, unlike many other eukaryotes, Giardia does not synthesize lipids de novo, but rather depends on exogenous sources for both energy production and organelle or membrane biogenesis. It is not known how lipid molecules are taken up by this parasite and if endocytic pathways are involved in this process. In this investigation, we tested the hypothesis that highly regulated and selective lipid transport machinery is present in Giardia and necessary for the efficient internalization and intracellular targeting of ceramide molecules, the major sphingolipid precursor. Using metabolic and pathway inhibitors, we demonstrate that ceramide is internalized through endocytic pathways and is primarily targeted into perinuclear/endoplasmic reticulum membranes. Further investigations suggested that Giardia uses both clathrin-dependent pathways and the actin cytoskeleton for ceramide uptake, as well as microtubule filaments for intracellular localization and targeting. We speculate that this parasitic protozoan has evolved cytoskeletal and clathrin-dependent endocytic mechanisms for importing ceramide molecules from the cell exterior for the synthesis of membranes and vesicles during growth and differentiation.
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Affiliation(s)
- Yunuen Hernandez
- Infectious Diseases/Immunology, University of Texas at El Paso, TX 79968-0519, USA
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12
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Abstract
Secretory processes play an important role on the biology and life cycles of parasitic protozoa. This review focus on basic aspects, from a cell biology perspective, of the secretion of (a) micronemes, rhoptries and dense granules in members of the Apicomplexa group, where these organelles are involved in the process of protozoan penetration into the host cell, survival within the parasitophorous vacuole and subsequent egress from the host cell, (b) the Maurer's cleft in Plasmodium, a structure involved in the secretion of proteins synthesized by the intravacuolar parasite and transported through vesicles to the erythrocyte surface, (c) the secretion of macromolecules into the flagellar pocket of trypanosomatids, and (d) the secretion of proteins which make the cyst wall of Giardia and Entamoeba, with the formation of encystation vesicles.
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Affiliation(s)
- Wanderley de Souza
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Ilha do Fundão, 21949-900 Rio de Janeiro, RJ, Brazil.
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13
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Gottig N, Elías EV, Quiroga R, Nores MJ, Solari AJ, Touz MC, Luján HD. Active and passive mechanisms drive secretory granule biogenesis during differentiation of the intestinal parasite Giardia lamblia. J Biol Chem 2006; 281:18156-66. [PMID: 16611634 DOI: 10.1074/jbc.m602081200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The parasitic protozoan Giardia lamblia undergoes important changes to survive outside the intestine of its host by differentiating into infective cysts. During encystation, three cyst wall proteins (CWPs) are specifically expressed and concentrated within encystation-specific secretory vesicles (ESVs). ESVs are electron-dense secretory granules that transport CWPs before exocytosis and extracellular polymerization into a rigid cyst wall. Because secretory granules form at the trans-Golgi in higher eukaryotes and because Giardia lacks an identifiable Golgi apparatus, the aim of this work was to investigate the molecular basis of secretory granule formation in Giardia by examining the role of CWPs in this process. Although CWP1, CWP2, and CWP3 are structurally similar in their 26-kDa leucine-rich overlapping region, CWP2 is distinguished by the presence of a 13-kDa C-terminal basic extension. In non-encysting trophozoites, expression of different CWP chimeras showed that the CWP2 basic extension is necessary for biogenesis of ESVs, which occurs in a compartment derived from the endoplasmic reticulum. Nevertheless, the CWP2 basic extension per se is insufficient to trigger ESV formation, indicating that other domains in CWPs are also required. We found that CWP2 is a key regulator of ESV formation by acting as an aggregation factor for CWP1 and CWP3 through interactions mediated by its conserved region. CWP2 also acts as a ligand for sorting via its C-terminal basic extension. These findings show that granule biogenesis requires complex interactions among granule components and membrane receptors.
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Affiliation(s)
- Natalia Gottig
- Instituto de Investigaciones Médicas Mercedes y Martín Ferreyra, Consejo Nacional de Investigaciones Científicas y Técnicas, Friuli 2434, CP 5000 Córdoba, Argentina
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14
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Lanfredi-Rangel A, Attias M, Reiner DS, Gillin FD, De Souza W. Fine structure of the biogenesis of Giardia lamblia encystation secretory vesicles. J Struct Biol 2003; 143:153-63. [PMID: 12972352 DOI: 10.1016/s1047-8477(03)00123-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Synthesis, transport, and assembly of the extracellular cyst wall is the hallmark of Giardia lamblia encystation. Much is known of the biochemical pathways and their regulation. However, from a cell biology point of view, the biogenesis of the encystation specific vesicles (ESVs) that transport cyst wall proteins to the periphery of the cell is poorly understood. Therefore, we exploited a number of complementary ultrastructural approaches to test the hypothesis that the formation of ESVs utilizes a novel regulated secretory pathway. We analyzed parasites at different stages of encystation in vitro by electron microscopy of thin sections, freeze fracture replicas, and three-dimensional reconstruction from serial sections of cells fixed for cytochemical localization of the endoplasmic reticulum (ER) marker, glucose 6-phosphatase. We also used a stereological approach to determine the area occupied by the ER, clefts, ESVs, and cyst wall. Taken together, our kinetic data suggest that some ER cisternae first dilate to form clefts, which enlarge into the ESVs. Living non-encysting and early-encysting trophozoites were labeled around the periphery of both nuclei with C(6)-NBD-ceramide. At 18-21 h, outward migration of some ESVs frequently caused protrusions at the periphery of encysting trophozoites. The presence of lysosome-like peripheral vesicles between the ESV and plasma membrane of the cell was confirmed using acridine orange, an acidic compartment marker. Our data suggest that G. lamblia has a novel secretory pathway in which certain functions of the ER and Golgi co-localize spatially and temporally. These studies will increase understanding of the evolutionary appearance of regulated secretory pathways for assembly of a primitive extracellular matrix in an early diverging eukaryote.
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Affiliation(s)
- A Lanfredi-Rangel
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, CCS, UFRJ, Bloco G-SS, Av Brig Trompowsky, s/no, CEP 21949-900, Rio de Janeiro, RJ, Brazil
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15
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Marti M, Regös A, Li Y, Schraner EM, Wild P, Müller N, Knopf LG, Hehl AB. An ancestral secretory apparatus in the protozoan parasite Giardia intestinalis. J Biol Chem 2003; 278:24837-48. [PMID: 12711599 DOI: 10.1074/jbc.m302082200] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The protozoan parasite Giardia intestinalis belongs to one of the earliest diverged eukaryotic lineages. This is also reflected in a simple intracellular organization, as Giardia lacks common subcellular compartments such as mitochondria, peroxisomes, and apparently also a Golgi apparatus. During encystation, developmentally regulated formation of large secretory compartments containing cyst wall material occurs. Despite the lack of any morphological similarities, these encystation-specific vesicles (ESVs) show several biochemical characteristics of maturing Golgi cisternae. Previous studies suggested that Golgi structure and function are induced only during encystation in Giardia, giving rise to the hypothesis that ESVs, as a Giardia Golgi equivalent, are generated de novo. Alternatively, ESV compartments could be built on the template structure of a cryptic Golgi in trophozoites in response to ER export of cyst wall material during encystation. We addressed this question by defining the molecular framework of the Giardia secretory apparatus using a comparative genomic approach. Analysis of the corresponding transcriptome during growth and encystation revealed surprisingly little stage-specific regulation. A panel of antibodies was generated against selected marker proteins to investigate the developmental dynamics of the endomembrane system. We show evidence that Giardia accommodates the export of large amounts of cyst wall material through re-organization of membrane compartment(s) in trophozoites with biochemical similarities to ESVs. This suggests that ESVs are selectively stabilized Golgi-like compartments in a unique and archetypical secretory system, which arise from a structural template in trophozoites rather than being generated de novo.
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Affiliation(s)
- Matthias Marti
- Institute of Parasitology, University of Zürich, Switzerland
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16
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Abstract
In the present study it was demonstrated the existence of a new set of membrane-bounded vesicles in Giardia lamblia. They were found in dividing and non-dividing trophozoites studied by routine transmission electron microscopy, freeze-fracture and Thiéry's technique. Encysting cells were not studied. These vesicles appear different to the previously reported components of the Giardia endomembranous system, such as the endoplasmic reticulum (ER), lysosome-like peripheral vesicles (PV), and the encystation-specific vesicles (ESV) that appear during trophozoite differentiation into cysts. They measure 100-150 nm in diameter, and thus are smaller than the peripheral vesicles, and the encystation-specific vesicles (ESV). They were found in clusters, scattered throughout the cytoplasm, but preferentially located close to the nuclei, axonemes, median bodies, and ER profiles. These internal vesicles are roughly spherical, and their contents present different electron densities and are more electrondense than those of the peripheral vesicles. They appeared to be budding from the outer nuclear membrane envelope. These cytoplasmic vesicles were found only in cells with very good fixation. Only few cells in the same preparation exhibited these vesicles.
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17
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Iwabe N, Miyata T. Kinesin-related genes from diplomonad, sponge, amphioxus, and cyclostomes: divergence pattern of kinesin family and evolution of giardial membrane-bounded organella. Mol Biol Evol 2002; 19:1524-33. [PMID: 12200480 DOI: 10.1093/oxfordjournals.molbev.a004215] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
To understand the question of whether divergence of eukaryotic genes by gene duplications and domain shufflings proceeded gradually or intermittently during evolution, we have cloned and sequenced Giardia lamblia cDNAs encoding kinesins and kinesin-related proteins and have obtained 13 kinesin-related cDNAs, some of which are likely homologs of vertebrate kinesins involved in vesicle transfer to ER, Golgi, and plasma membrane. A phylogenetic tree of the kinesin family revealed that most gene duplications that gave rise to different kinesin subfamilies with distinct functions have been completed before the earliest divergence of extant eukaryotes. This suggests that the complex endomembrane system has arisen very early in eukaryotic evolution, and the diminutive ER and Golgi apparatus recognized in the giardial cells, together with the absence of mitochondria, might be characters acquired secondarily during the evolution of parasitism. To understand the divergence pattern of the kinesin family in the lineage leading to vertebrates, seven more Unc104-related cDNAs have been cloned from sponge, amphioxus, hagfish, and lamprey. The divergence pattern of the animal Unc104/KIF1 subfamily is characterized by two active periods in gene duplication interrupted by a considerably long period of silence, instead of proceeding gradually: animals underwent extensive gene duplications before the parazoan-eumetazoan split. In the early evolution of vertebrates around the cyclostome-gnathostome split, further gene duplications occurred, by which a variety of genes with similar structures over the entire regions were generated. This pattern of divergence is similar to those of animal genes involved in cell-cell communication and developmental control.
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Affiliation(s)
- Naoyuki Iwabe
- Department of Biophysics, Graduate School of Science, Kyoto University, Japan
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18
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Abstract
The phylogeny of the commonest protozoal agent of intestinal disease, Giardia, is unclear. Although recent intensive research suggests this important human parasite is an early branching eukaryote that evolved before the endosymbiotic origin of mitochondria, there is also evidence to suggest that, as a highly evolved parasite, it has lost many of its ancestral characteristics. In this case, these organisms might have arisen much more recently from aerobic free-living flagellates.
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Affiliation(s)
- David Lloyd
- Microbiology (BIOSI), Cardiff University, PO Box 915, Wales, CF10 3TL., Cardiff, UK.
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19
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Abstract
Giardia lamblia is a common cause of diarrhea in humans and other mammals throughout the world. It can be distinguished from other Giardia species by light or electron microscopy. The two major genotypes of G. lamblia that infect humans are so different genetically and biologically that they may warrant separate species or subspecies designations. Trophozoites have nuclei and a well-developed cytoskeleton but lack mitochondria, peroxisomes, and the components of oxidative phosphorylation. They have an endomembrane system with at least some characteristics of the Golgi complex and encoplasmic reticulum, which becomes more extensive in encysting organisms. The primitive nature of the organelles and metabolism, as well as small-subunit rRNA phylogeny, has led to the proposal that Giardia spp. are among the most primitive eukaryotes. G. lamblia probably has a ploidy of 4 and a genome size of approximately 10 to 12 Mb divided among five chromosomes. Most genes have short 5' and 3' untranslated regions and promoter regions that are near the initiation codon. Trophozoites exhibit antigenic variation of an extensive repertoire of cysteine-rich variant-specific surface proteins. Expression is allele specific, and changes in expression from one vsp gene to another have not been associated with sequence alterations or gene rearrangements. The Giardia genome project promises to greatly increase our understanding of this interesting and enigmatic organism.
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Affiliation(s)
- R D Adam
- Department of Medicine, University of Arizona College of Medicine, 1501N. Campbell, Tucson, AZ 85724-5049, USA.
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20
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Damaso CR, Esposito JJ, Condit RC, Moussatché N. An emergent poxvirus from humans and cattle in Rio de Janeiro State: Cantagalo virus may derive from Brazilian smallpox vaccine. Virology 2000; 277:439-49. [PMID: 11080491 DOI: 10.1006/viro.2000.0603] [Citation(s) in RCA: 199] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The biological properties of poxvirus isolates from skin lesions on dairy cows and milkers during recent exanthem episodes in Cantagalo County, Rio de Janeiro State, Brazil, were more like vaccinia virus (VV) than cowpox virus. PCR amplification of the hemagglutinin (HA) gene substantiated the isolate classification as an Old World orthopoxvirus, and alignment of the HA sequences with those of other orthopoxviruses indicated that all the isolates represented a single strain of VV, which we have designated Cantagalo virus (CTGV). HA sequences of the Brazilian smallpox vaccine strain (VV-IOC), used over 20 years ago, and CTGV showed 98.2% identity; phylogeny inference of CTGV, VV-IOC, and 12 VV strains placed VV-IOC and CTGV together in a distinct clade. Viral DNA restriction patterns and protein profiles showed a few differences between VV-IOC and CTGV. Together, the data suggested that CTGV may have derived from VV-IOC by persisting in an indigenous animal(s), accumulating polymorphisms, and now emerging in cattle and milkers as CTGV. CTGV may represent the first case of long-term persistence of vaccinia in the New World.
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Affiliation(s)
- C R Damaso
- Laboratório de Biologia Molecular de Vírus, Instituto de Biofísica Carlos Chagas Filho, CCS, Rio de Janeiro, RJ 21941-900, Brazil
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