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Sekar P, Rajagopalan S, Shabani E, Kanjee U, Schureck MA, Arora G, Peterson ME, Traore B, Crompton PD, Duraisingh MT, Desai SA, Long EO. NK cell-induced damage to P.falciparum-infected erythrocytes requires ligand-specific recognition and releases parasitophorous vacuoles that are phagocytosed by monocytes in the presence of immune IgG. PLoS Pathog 2023; 19:e1011585. [PMID: 37939134 PMCID: PMC10659167 DOI: 10.1371/journal.ppat.1011585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 11/20/2023] [Accepted: 10/24/2023] [Indexed: 11/10/2023] Open
Abstract
Natural killer (NK) cells lyse virus-infected cells and transformed cells through polarized delivery of lytic effector molecules into target cells. We have shown that NK cells lyse Plasmodium falciparum-infected red blood cells (iRBC) via antibody-dependent cellular cytotoxicity (ADCC). A high frequency of adaptive NK cells, with elevated intrinsic ADCC activity, in people chronically exposed to malaria transmission is associated with reduced parasitemia and resistance to disease. How NK cells bind to iRBC and the outcome of iRBC lysis by NK cells has not been investigated. We applied gene ablation in inducible erythrocyte precursors and antibody-blocking experiments with iRBC to demonstrate a central role of CD58 and ICAM-4 as ligands for adhesion by NK cells via CD2 and integrin αMβ2, respectively. Adhesion was dependent on opsonization of iRBC by IgG. Live imaging and quantitative flow cytometry of NK-mediated ADCC toward iRBC revealed that damage to the iRBC plasma membrane preceded damage to P. falciparum within parasitophorous vacuoles (PV). PV were identified and tracked with a P.falciparum strain that expresses the PV membrane-associated protein EXP2 tagged with GFP. After NK-mediated ADCC, PV were either found inside iRBC ghosts or released intact and devoid of RBC plasma membrane. Electron microscopy images of ADCC cultures revealed tight NK-iRBC synapses and free vesicles similar in size to GFP+ PV isolated from iRBC lysates by cell sorting. The titer of IgG in plasma of malaria-exposed individuals that bound PV was two orders of magnitude higher than IgG that bound iRBC. This immune IgG stimulated efficient phagocytosis of PV by primary monocytes. The selective NK-mediated damage to iRBC, resulting in release of PV, and subsequent phagocytosis of PV by monocytes may combine for efficient killing and removal of intra-erythrocytic P.falciparum parasite. This mechanism may mitigate the inflammation and malaria symptoms during blood-stage P. falciparum infection.
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Affiliation(s)
- Padmapriya Sekar
- Molecular and Cellular Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Sumati Rajagopalan
- Molecular and Cellular Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Estela Shabani
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Usheer Kanjee
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Marc A. Schureck
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Gunjan Arora
- Molecular and Cellular Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Mary E. Peterson
- Molecular and Cellular Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
- Malaria Infection Biology and Immunity Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Boubacar Traore
- Malaria Research and Training Center, Mali International Center for Excellence in Research, University of Sciences, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Peter D. Crompton
- Malaria Infection Biology and Immunity Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Manoj T. Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Sanjay A. Desai
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Eric O. Long
- Molecular and Cellular Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
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2
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Maier AG, van Ooij C. The role of cholesterol in invasion and growth of malaria parasites. Front Cell Infect Microbiol 2022; 12:984049. [PMID: 36189362 PMCID: PMC9522969 DOI: 10.3389/fcimb.2022.984049] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/15/2022] [Indexed: 11/24/2022] Open
Abstract
Malaria parasites are unicellular eukaryotic pathogens that develop through a complex lifecycle involving two hosts, an anopheline mosquito and a vertebrate host. Throughout this lifecycle, the parasite encounters widely differing conditions and survives in distinct ways, from an intracellular lifestyle in the vertebrate host to exclusively extracellular stages in the mosquito. Although the parasite relies on cholesterol for its growth, the parasite has an ambiguous relationship with cholesterol: cholesterol is required for invasion of host cells by the parasite, including hepatocytes and erythrocytes, and for the development of the parasites in those cells. However, the parasite is unable to produce cholesterol itself and appears to remove cholesterol actively from its own plasma membrane, thereby setting up a cholesterol gradient inside the infected host erythrocyte. Overall a picture emerges in which the parasite relies on host cholesterol and carefully controls its transport. Here, we describe the role of cholesterol at the different lifecycle stages of the parasites.
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Affiliation(s)
- Alexander G. Maier
- Research School of Biology, The Australian National University, Canberra ACT, Australia
- *Correspondence: Alexander G. Maier, ; Christiaan van Ooij,
| | - Christiaan van Ooij
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
- *Correspondence: Alexander G. Maier, ; Christiaan van Ooij,
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Protein Profiling of Malaria-Derived Extracellular Vesicles Reveals Distinct Subtypes. MEMBRANES 2022; 12:membranes12040397. [PMID: 35448366 PMCID: PMC9033066 DOI: 10.3390/membranes12040397] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/23/2022] [Accepted: 03/29/2022] [Indexed: 02/04/2023]
Abstract
Malaria is caused by obligate intracellular parasites belonging to the genus Plasmodium. Red blood cells (RBCs) infected with different stages of Plasmodium spp. release extracellular vesicles (EVs). Extensive studies have recently shown that these EVs are involved in key aspects of the parasite’s biology and disease pathogenesis. However, they are yet to be fully characterized. The blood stages of Plasmodium spp., namely the rings, trophozoites and schizonts, are phenotypically distinct, hence, may induce the release of characteristically different EVs from infected RBCs. To gain insights into the biology and biogenesis of malaria EVs, it is important to characterize their biophysical and biochemical properties. By differential centrifugation, we isolated EVs from in vitro cultures of RBCs infected with different stages of Plasmodium falciparum. We performed a preliminary characterization of these EVs and observed that important EV markers were differentially expressed in EVs with different sedimentation properties as well as across EVs released from ring-, trophozoite- or schizont-infected RBCs. Our findings show that RBCs infected with different stages of malaria parasites release EVs with distinct protein expression profiles.
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4
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Koudatsu S, Masatani T, Konishi R, Asada M, Hakimi H, Kurokawa Y, Tomioku K, Kaneko O, Fujita A. Glycosphingolipid GM3 is localized in both exoplasmic and cytoplasmic leaflets of Plasmodium falciparum malaria parasite plasma membrane. Sci Rep 2021; 11:14890. [PMID: 34290278 PMCID: PMC8295280 DOI: 10.1038/s41598-021-94037-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 06/28/2021] [Indexed: 11/22/2022] Open
Abstract
Lipid rafts, sterol-rich and sphingolipid-rich microdomains on the plasma membrane are important in processes like cell signaling, adhesion, and protein and lipid transport. The virulence of many eukaryotic parasites is related to raft microdomains on the cell membrane. In the malaria parasite Plasmodium falciparum, glycosylphosphatidylinositol-anchored proteins, which are important for invasion and are possible targets for vaccine development, are localized in the raft. However, rafts are poorly understood. We used quick-freezing and freeze-fracture immuno-electron microscopy to examine the localization of monosialotetrahexosylganglioside (GM1) and monosialodihexosylganglioside (GM3), putative raft microdomain components in P. falciparum and infected erythrocytes. This method immobilizes molecules in situ, minimizing artifacts. GM3 was localized in the exoplasmic (EF) and cytoplasmic leaflets (PF) of the parasite and the parasitophorous vacuole (PV) membranes, but solely in the EF of the infected erythrocyte membrane, as in the case for uninfected erythrocytes. Phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) was localized solely in the PF of erythrocyte, parasite, and PV membranes. This is the first time that GM3, the major component of raft microdomains, was found in the PF of a biological membrane. The unique localization of raft microdomains may be due to P. falciparum lipid metabolism and its unique biological processes, like protein transport from the parasite to infected erythrocytes.
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Affiliation(s)
- Shiomi Koudatsu
- Department of Molecular and Cell Biology and Biochemistry, Basic Veterinary Science, Faculty of Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima, 890-0065, Japan
| | - Tatsunori Masatani
- Transboundary Animal Diseases Research Center, Joint Faculty of Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima, 890-0065, Japan.,Laboratory of Zoonotic Diseases, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
| | - Rikako Konishi
- Department of Molecular and Cell Biology and Biochemistry, Basic Veterinary Science, Faculty of Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima, 890-0065, Japan
| | - Masahito Asada
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Sakamoto 1-12-4, Nagasaki, 852-8523, Japan.,National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, 080-8555, Japan
| | - Hassan Hakimi
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Sakamoto 1-12-4, Nagasaki, 852-8523, Japan.,National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, 080-8555, Japan
| | - Yuna Kurokawa
- Department of Molecular and Cell Biology and Biochemistry, Basic Veterinary Science, Faculty of Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima, 890-0065, Japan
| | - Kanna Tomioku
- Department of Molecular and Cell Biology and Biochemistry, Basic Veterinary Science, Faculty of Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima, 890-0065, Japan
| | - Osamu Kaneko
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Sakamoto 1-12-4, Nagasaki, 852-8523, Japan
| | - Akikazu Fujita
- Department of Molecular and Cell Biology and Biochemistry, Basic Veterinary Science, Faculty of Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima, 890-0065, Japan.
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4D analysis of malaria parasite invasion offers insights into erythrocyte membrane remodeling and parasitophorous vacuole formation. Nat Commun 2021; 12:3620. [PMID: 34131147 PMCID: PMC8206130 DOI: 10.1038/s41467-021-23626-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 04/30/2021] [Indexed: 12/15/2022] Open
Abstract
Host membrane remodeling is indispensable for viruses, bacteria, and parasites, to subvert the membrane barrier and obtain entry into cells. The malaria parasite Plasmodium spp. induces biophysical and molecular changes to the erythrocyte membrane through the ordered secretion of its apical organelles. To understand this process and address the debate regarding how the parasitophorous vacuole membrane (PVM) is formed, we developed an approach using lattice light-sheet microscopy, which enables the parasite interaction with the host cell membrane to be tracked and characterized during invasion. Our results show that the PVM is predominantly formed from the erythrocyte membrane, which undergoes biophysical changes as it is remodeled across all stages of invasion, from pre-invasion through to PVM sealing. This approach enables a functional interrogation of parasite-derived lipids and proteins in PVM biogenesis and echinocytosis during Plasmodium falciparum invasion and promises to yield mechanistic insights regarding how this is more generally orchestrated by other intracellular pathogens. Here, Geoghegan, Evelyn et al. provide a lattice light-sheet microscopy based 4D imaging pipeline to quantitatively investigate Plasmodium spp. invasion and show that the nascent parasitophorous vacuole is predominantly formed from host’s erythrocyte membrane and undergoes continuous remodeling throughout invasion.
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Jennings W, Epand RM. CDP-diacylglycerol, a critical intermediate in lipid metabolism. Chem Phys Lipids 2020; 230:104914. [PMID: 32360136 DOI: 10.1016/j.chemphyslip.2020.104914] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 04/01/2020] [Accepted: 04/13/2020] [Indexed: 12/13/2022]
Abstract
The roles of lipids expand beyond the basic building blocks of biological membranes. In addition to forming complex and dynamic barriers, the thousands of different lipid species in the cell contribute to essentially all the processes of life. Specific lipids are increasingly identified in cellular processes, including signal transduction, membrane trafficking, metabolic control and protein regulation. Tight control of their synthesis and degradation is essential for homeostasis. Most of the lipid molecules in the cell originate from a small number of critical intermediates. Thus, regulating the synthesis of intermediates is essential for lipid homeostasis and optimal biological functions. Cytidine diphosphate diacylglycerol (CDP-DAG) is an intermediate which occupies a branch point in lipid metabolism. CDP-DAG is incorporated into different synthetic pathways to form distinct phospholipid end-products depending on its location of synthesis. Identification and characterization of CDP-DAG synthases which catalyze the synthesis of CDP-DAG has been hampered by difficulties extracting these membrane-bound enzymes for purification. Recent developments have clarified the cellular localization of the CDP-DAG synthases and identified a new unrelated CDP-DAG synthase enzyme. These findings have contributed to a deeper understanding of the extensive synthetic and signaling networks stemming from this key lipid intermediate.
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Affiliation(s)
- William Jennings
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
| | - Richard M Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada.
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7
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Real-time cholesterol sorting in Plasmodium falciparum-erythrocytes as revealed by 3D label-free imaging. Sci Rep 2020; 10:2794. [PMID: 32066816 PMCID: PMC7026401 DOI: 10.1038/s41598-020-59552-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 01/28/2020] [Indexed: 12/18/2022] Open
Abstract
Cholesterol, a necessary component of animal cell membranes, is also needed by the lethal human malaria parasite Plasmodium falciparum. Because P. falciparum lacks a cholesterol synthesis pathway and malaria patients have low blood cholesterol, we speculated that it scavenges cholesterol from them in some way. We used time-lapse holotomographic microscopy to observe cholesterol transport in live P. falciparum parasites and structurally investigate erythrocyte membranes, both during and after P. falciparum invasion of human erythrocytes. After P. falciparum initially acquired free cholesterol or inner erythrocytic membrane-derived cholesterol, we observed budding lipid membranes elongating into the cytosol and/or membrane segments migrating there and eventually fusing with the parasite membranes, presumably at the parasitophorous vacuole membrane (PVM). Finally, the cholesterol-containing segments were seen to surround the parasite nucleus. Our imaging data suggest that a novel membrane transport system operates in the cytosol of P. falciparum-infected erythrocytes as a cholesterol import system, likely between the PVM and the erythrocyte membrane, and that this transportation process occurs during the live erythrocyte stages of P. falciparum.
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8
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Sherling ES, van Ooij C. Host cell remodeling by pathogens: the exomembrane system in Plasmodium-infected erythrocytes. FEMS Microbiol Rev 2017; 40:701-21. [PMID: 27587718 PMCID: PMC5007283 DOI: 10.1093/femsre/fuw016] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2016] [Indexed: 12/22/2022] Open
Abstract
Malaria is caused by infection of erythrocytes by parasites of the genus Plasmodium. To survive inside erythrocytes, these parasites induce sweeping changes within the host cell, one of the most dramatic of which is the formation of multiple membranous compartments, collectively referred to as the exomembrane system. As an uninfected mammalian erythrocyte is devoid of internal membranes, the parasite must be the force and the source behind the formation of these compartments. Even though the first evidence of the presence these of internal compartments was obtained over a century ago, their functions remain mostly unclear, and in some cases completely unknown, and the mechanisms underlying their formation are still mysterious. In this review, we provide an overview of the different parts of the exomembrane system, describing the parasitophorous vacuole, the tubovesicular network, Maurer's clefts, the caveola-vesicle complex, J dots and other mobile compartments, and the small vesicles that have been observed in Plasmodium-infected cells. Finally, we combine the data into a simplified view of the exomembrane system and its relation to the alterations of the host erythrocyte. Plasmodium parasites remodel the host erythrocyte in various ways, including the formation of several membranous compartments, together referred to as the exomembrane system, within the erythrocyte cytosol that together are key to the sweeping changes in the host cell.
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Affiliation(s)
- Emma S Sherling
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London NW7 1AA, UK Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Christiaan van Ooij
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London NW7 1AA, UK
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9
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Drug-induced endovesiculation of erythrocytes is modulated by the dynamics in the cytoskeleton/membrane interaction. Blood Cells Mol Dis 2017; 64:15-22. [DOI: 10.1016/j.bcmd.2017.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 03/06/2017] [Accepted: 03/06/2017] [Indexed: 11/24/2022]
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10
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Abstract
Erythropoiesis is tightly regulated by the growth factor erythropoietin (Epo). Signal activation begins when Epo engages its cognate receptor, Epo-R, triggering receptor homodimerization, and recruitment of signaling intermediates including Jak2 that phosphorylates both the receptor cytoplasmic tail and downstream effectors including the transcription factor, STAT5. Transcription factors subsequently activate transcription of prosurvival and prodifferentiation genes responsible for red blood cell production. The fidelity of Epo-R signaling is dependent upon residence within detergent insoluble membrane lipid raft fractions. Lipid rafts are membrane microdomains that serve as signaling scaffolds composed of densely packed sphingolipids and cholesterol where receptors and intermediate signaling proteins are recruited and interact to execute stimuli. Disruption of lipid rafts is detrimental to Epo signaling, a phenomenon that may be utilized to design novel therapeutics for conditions in which Epo signaling is deficient. Here, we review the Epo signaling cascade, particularly, as it relates to localization and dependence on lipid rafts, and discuss considerations for novel therapeutic design.
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Affiliation(s)
- Kathy McGraw
- Division of Clinical Sciences, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, United States.
| | - Alan List
- Division of Clinical Sciences, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, United States
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11
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Abstract
Coxiella burnetii is an intracellular bacterial pathogen and a significant cause of culture-negative endocarditis in the United States. Upon infection, the nascent Coxiella phagosome fuses with the host endocytic pathway to form a large lysosome-like vacuole called the parasitophorous vacuole (PV). The PV membrane is rich in sterols, and drugs perturbing host cell cholesterol homeostasis inhibit PV formation and bacterial growth. Using cholesterol supplementation of a cholesterol-free cell model system, we found smaller PVs and reduced Coxiella growth as cellular cholesterol concentration increased. Further, we observed in cells with cholesterol a significant number of nonfusogenic PVs that contained degraded bacteria, a phenotype not observed in cholesterol-free cells. Cholesterol had no effect on axenic Coxiella cultures, indicating that only intracellular bacteria are sensitive to cholesterol. Live-cell microscopy revealed that both plasma membrane-derived cholesterol and the exogenous cholesterol carrier protein low-density lipoprotein (LDL) traffic to the PV. To test the possibility that increasing PV cholesterol levels affects bacterial survival, infected cells were treated with U18666A, a drug that traps cholesterol in lysosomes and PVs. U18666A treatment led to PVs containing degraded bacteria and a significant loss in bacterial viability. The PV pH was significantly more acidic in cells with cholesterol or cells treated with U18666A, and the vacuolar ATPase inhibitor bafilomycin blocked cholesterol-induced PV acidification and bacterial death. Additionally, treatment of infected HeLa cells with several FDA-approved cholesterol-altering drugs led to a loss of bacterial viability, a phenotype also rescued by bafilomycin. Collectively, these data suggest that increasing PV cholesterol further acidifies the PV, leading to Coxiella death. The intracellular Gram-negative bacterium Coxiella burnetii is a significant cause of culture-negative infectious endocarditis, which can be fatal if untreated. The existing treatment strategy requires prolonged antibiotic treatment, with a 10-year mortality rate of 19% in treated patients. Therefore, new clinical therapies are needed and can be achieved by better understanding C. burnetii pathogenesis. Upon infection of host cells, C. burnetii grows within a specialized replication niche, the parasitophorous vacuole (PV). Recent data have linked cholesterol to intracellular C. burnetii growth and PV formation, leading us to further decipher the role of cholesterol during C. burnetii-host interaction. We observed that increasing PV cholesterol concentration leads to increased acidification of the PV and bacterial death. Further, treatment with FDA-approved drugs that alter host cholesterol homeostasis also killed C. burnetii through PV acidification. Our findings suggest that targeting host cholesterol metabolism might prove clinically efficacious in controlling C. burnetii infection.
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Tribensky A, Graf AW, Diehl M, Fleck W, Przyborski JM. Trafficking of PfExp1 to the parasitophorous vacuolar membrane of Plasmodium falciparum is independent of protein folding and the PTEX translocon. Cell Microbiol 2017; 19. [PMID: 27892646 DOI: 10.1111/cmi.12710] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/19/2016] [Accepted: 11/24/2016] [Indexed: 12/13/2022]
Abstract
Having entered the mature human erythrocyte, the malaria parasite survives and propagates within a parasitophorous vacuole, a membrane-bound compartment separating the parasite from the host cell cytosol. The bounding membrane of this vacuole, referred to as the parasitophorous vacuolar membrane (PVM), contains parasite-encoded proteins, but how these membrane proteins are trafficked to the PVM remains unknown. Here, we have studied the trafficking of PfExp1 to the PVM. We find that trafficking of PfExp1 to the PVM is independent of the folding state of the protein and also continues unabated upon inactivation of the PVM translocon Plasmodium Translocon of Exported proteins (PTEX). Our data strongly suggest that the trafficking of membrane proteins to the PVM occurs by as yet unknown mechanism, potentially unique to Plasmodium.
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Affiliation(s)
- Anke Tribensky
- Department of Parasitology, University of Marburg, Marburg, Germany
| | - Andreas W Graf
- Department of Parasitology, University of Marburg, Marburg, Germany
| | - Mathias Diehl
- Department of Parasitology, University of Marburg, Marburg, Germany
| | - Wiebke Fleck
- Department of Parasitology, University of Marburg, Marburg, Germany
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13
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Physicochemical Aspects of the Plasmodium chabaudi-Infected Erythrocyte. BIOMED RESEARCH INTERNATIONAL 2015; 2015:642729. [PMID: 26557685 PMCID: PMC4628737 DOI: 10.1155/2015/642729] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 07/16/2015] [Accepted: 07/21/2015] [Indexed: 11/17/2022]
Abstract
Membrane electrochemical potential is a feature of the molecular profile of the cell membrane and the two-dimensional arrangement of its charge-bearing molecules. Plasmodium species, the causative agents of malaria, are intracellular parasites that remodel host erythrocytes by expressing their own proteins on erythrocyte membranes. Although various aspects of the modifications made to the host erythrocyte membrane have been extensively studied in some human Plasmodium species (such as Plasmodium falciparum), details of the structural and molecular biological modifications made to host erythrocytes by nonhuman Plasmodium parasites have not been studied. We employed zeta potential analysis of erythrocytes parasitized by P. chabaudi, a nonhuman Plasmodium parasite. From these measurements, we found that the surface potential shift was more negative for P. chabaudi-infected erythrocytes than for P. falciparum-infected erythrocytes. However, electron microscopic analysis of the surface of P. chabaudi-infected erythrocytes did not reveal any modifications as compared with nonparasitized erythrocytes. These results suggest that differences in the membrane modifications found herein represent unique attributes related to the pathogenesis profiles of the two different malaria parasite species in different host animals and that these features have been acquired through parasite adaptations acquired over long evolutionary time periods.
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Membrane rafts in the erythrocyte membrane: a novel role of MPP1p55. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 842:61-78. [PMID: 25408337 DOI: 10.1007/978-3-319-11280-0_5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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15
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Tokumasu F, Crivat G, Ackerman H, Hwang J, Wellems TE. Inward cholesterol gradient of the membrane system in P. falciparum-infected erythrocytes involves a dilution effect from parasite-produced lipids. Biol Open 2014; 3:529-41. [PMID: 24876390 PMCID: PMC4058088 DOI: 10.1242/bio.20147732] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmodium falciparum (Pf) infection remodels the human erythrocyte with new membrane systems, including a modified host erythrocyte membrane (EM), a parasitophorous vacuole membrane (PVM), a tubulovesicular network (TVN), and Maurer's clefts (MC). Here we report on the relative cholesterol contents of these membranes in parasitized normal (HbAA) and hemoglobin S-containing (HbAS, HbAS) erythrocytes. Results from fluorescence lifetime imaging microscopy (FLIM) experiments with a cholesterol-sensitive fluorophore show that membrane cholesterol levels in parasitized erythrocytes (pRBC) decrease inwardly from the EM, to the MC/TVN, to the PVM, and finally to the parasite membrane (PM). Cholesterol depletion of pRBC by methyl-β-cyclodextrin treatment caused a collapse of this gradient. Lipid and cholesterol exchange data suggest that the cholesterol gradient involves a dilution effect from non-sterol lipids produced by the parasite. FLIM signals from the PVM or PM showed little or no difference between parasitized HbAA vs HbS-containing erythrocytes that differed in lipid content, suggesting that malaria parasites may regulate the cholesterol contents of the PVM and PM independently of levels in the host cell membrane. Cholesterol levels may affect raft structures and the membrane trafficking and sorting functions that support Pf survival in HbAA, HbAS and HbSS erythrocytes.
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Affiliation(s)
- Fuyuki Tokumasu
- Malaria Genetics Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8132, USA Present address: Department of Lipidomics, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Georgeta Crivat
- Malaria Genetics Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8132, USA Quantum Electronics and Photonics Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Hans Ackerman
- Malaria Genetics Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8132, USA
| | - Jeeseong Hwang
- Quantum Electronics and Photonics Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Thomas E Wellems
- Malaria Genetics Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8132, USA
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16
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Rosa IDA, Atella G, Benchimol M. Tritrichomonas foetus displays classical detergent-resistant membrane microdomains on its cell surface. Protist 2014; 165:293-304. [PMID: 24742927 DOI: 10.1016/j.protis.2014.03.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 03/18/2014] [Accepted: 03/19/2014] [Indexed: 11/27/2022]
Abstract
Tritrichomonas foetus is a serious veterinary parasite that causes bovine trichomoniasis, a sexually transmitted disease that results in reproductive failure and considerable economic losses in areas that practice natural breeding. T. foetus is an extracellular parasite, which initially adheres to and infects the urogenital tract using a diverse array of surface glycoconjugates, including adhesins and extracellular matrix-binding molecules. However, the cellular mechanisms by which T. foetus colonizes mucosal surfaces and causes tissue damage are not well defined. Several studies have demonstrated the involvement of pathogen or host lipid rafts in cellular events that occur during pathogenesis, including adhesion, invasion and evasion of the immune response. In this study, we demonstrate that detergent-resistant membranes are present in the plasma membrane of T. foetus. We further demonstrate that microdomains are cholesterol-enriched and contain ganglioside GM1-like molecules. In addition, we demonstrate that lipid microdomains do not participate in T. foetus adhesion to host cells. However, the use of agents that disrupt and disorganize the plasma membrane indicated the involvement of the T. foetus lipid microdomains, in cell division and in the formation of endoflagellar forms. Our results suggest that trophozoites and endoflagellar forms present a different plasma membrane organization.
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Affiliation(s)
- Ivone de Andrade Rosa
- Universidade Santa Úrsula, Rua Jornalista Orlando Dantas 59, Botafogo, CEP 22231-010 Rio de Janeiro, RJ, Brazil; Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil
| | - Georgia Atella
- Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Brazil
| | - Marlene Benchimol
- Universidade Santa Úrsula, Rua Jornalista Orlando Dantas 59, Botafogo, CEP 22231-010 Rio de Janeiro, RJ, Brazil.
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17
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In vivo splenic clearance correlates with in vitro deformability of red blood cells from Plasmodium yoelii-infected mice. Infect Immun 2014; 82:2532-41. [PMID: 24686065 DOI: 10.1128/iai.01525-13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent experimental and clinical studies suggest a crucial role of mechanical splenic filtration in the host's defense against malaria parasites. Subtle changes in red blood cell (RBC) deformability, caused by infection or drug treatment, could influence the pathophysiological outcome. However, in vitro deformability measurements have not been directly linked in vivo with the splenic clearance of RBCs. In this study, mice infected with malaria-inducing Plasmodium yoelii revealed that chloroquine treatment could lead to significant alterations to RBC deformability and increase clearance of both infected and uninfected RBCs in vivo. These results have clear implications for the mechanism of human malarial anemia, a severe pathological condition affecting malaria patients.
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18
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Disruption of lipid rafts interferes with the interaction of Toxoplasma gondii with macrophages and epithelial cells. BIOMED RESEARCH INTERNATIONAL 2014; 2014:687835. [PMID: 24734239 PMCID: PMC3964738 DOI: 10.1155/2014/687835] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 12/26/2013] [Accepted: 01/08/2014] [Indexed: 12/02/2022]
Abstract
The intracellular parasite Toxoplasma gondii can penetrate any warm-blooded animal cell. Conserved molecular assemblies of host cell plasma membranes should be involved in the parasite-host cell recognition. Lipid rafts are well-conserved membrane microdomains that contain high concentrations of cholesterol, sphingolipids, glycosylphosphatidylinositol, GPI-anchored proteins, and dually acylated proteins such as members of the Src family of tyrosine kinases. Disturbing lipid rafts of mouse peritoneal macrophages and epithelial cells of the lineage LLC-MK2 with methyl-beta cyclodextrin (MβCD) and filipin, which interfere with cholesterol or lidocaine, significantly inhibited internalization of T. gondii in both cell types, although adhesion remained unaffected in macrophages and decreased only in LLC-MK2 cells. Scanning and transmission electron microscopy confirmed these observations. Results are discussed in terms of the original role of macrophages as professional phagocytes versus the LLC-MK2 cell lineage originated from kidney epithelial cells.
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19
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Yam XY, Birago C, Fratini F, Di Girolamo F, Raggi C, Sargiacomo M, Bachi A, Berry L, Fall G, Currà C, Pizzi E, Breton CB, Ponzi M. Proteomic analysis of detergent-resistant membrane microdomains in trophozoite blood stage of the human malaria parasite Plasmodium falciparum. Mol Cell Proteomics 2013; 12:3948-61. [PMID: 24045696 DOI: 10.1074/mcp.m113.029272] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Intracellular pathogens contribute to a significant proportion of infectious diseases worldwide. The successful strategy of evading the immune system by hiding inside host cells is common to all the microorganism classes, which exploit membrane microdomains, enriched in cholesterol and sphingolipids, to invade and colonize the host cell. These assemblies, with distinct biochemical properties, can be isolated by means of flotation in sucrose density gradient centrifugation because they are insoluble in nonionic detergents at low temperature. We analyzed the protein and lipid contents of detergent-resistant membranes from erythrocytes infected by Plasmodium falciparum, the most deadly human malaria parasite. Proteins associated with membrane microdomains of trophic parasite blood stages (trophozoites) include an abundance of chaperones, molecules involved in vesicular trafficking, and enzymes implicated in host hemoglobin degradation. About 60% of the identified proteins contain a predicted localization signal suggesting a role of membrane microdomains in protein sorting/trafficking. To validate our proteomic data, we raised antibodies against six Plasmodium proteins not characterized previously. All the selected candidates were recovered in floating low-density fractions after density gradient centrifugation. The analyzed proteins localized either to internal organelles, such as the mitochondrion and the endoplasmic reticulum, or to exported membrane structures, the parasitophorous vacuole membrane and Maurer's clefts, implicated in targeting parasite proteins to the host erythrocyte cytosol or surface. The relative abundance of cholesterol and phospholipid species varies in gradient fractions containing detergent-resistant membranes, suggesting heterogeneity in the lipid composition of the isolated microdomain population. This study is the first report showing the presence of cholesterol-rich microdomains with distinct properties and subcellular localization in trophic stages of Plasmodium falciparum.
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Affiliation(s)
- Xue Yan Yam
- University Montpellier II, CNRS UMR 5235, 34095 Montpellier, Cedex 5, France
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20
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Rub A, Arish M, Husain SA, Ahmed N, Akhter Y. Host-lipidome as a potential target of protozoan parasites. Microbes Infect 2013; 15:649-60. [PMID: 23811020 DOI: 10.1016/j.micinf.2013.06.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 04/13/2013] [Accepted: 06/18/2013] [Indexed: 12/24/2022]
Abstract
Host-lipidome caters parasite interaction by acting as first line of recognition, attachment on the cell surface, intracellular trafficking, and survival of the parasite inside the host cell. Here, we summarize how protozoan parasites exploit host-lipidome by suppressing, augmenting, engulfing, remodeling and metabolizing lipids to achieve successful parasitism inside the host.
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Affiliation(s)
- Abdur Rub
- Infection and Immunity Lab, Department of Biotechnology, Jamia Millia Islamia (A Central University), New Delhi 110025, India.
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21
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Goldston AM, Powell RR, Temesvari LA. Sink or swim: lipid rafts in parasite pathogenesis. Trends Parasitol 2012; 28:417-26. [PMID: 22906512 DOI: 10.1016/j.pt.2012.07.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 07/16/2012] [Accepted: 07/17/2012] [Indexed: 12/26/2022]
Abstract
Lipid rafts, sterol- and sphingolipid-rich membrane microdomains, have been extensively studied in mammalian cells. Recently, lipid rafts have been shown to control virulence in a variety of parasites including Entamoeba histolytica, Giardia intestinalis, Leishmania spp., Plasmodium spp., Toxoplasma gondii, and Trypanosoma spp. Parasite rafts regulate adhesion to host and invasion, and parasite adhesion molecules often localize to rafts. Parasite rafts also control vesicle trafficking, motility, and cell signaling. Parasites disrupt host cell rafts; the dysregulation of host membrane function facilitates the establishment of infection and evasion of the host immune system. Discerning the mechanism by which lipid rafts regulate parasite pathogenesis is essential to our understanding of virulence. Such insight may guide the development of new drugs for disease management.
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Affiliation(s)
- Amanda M Goldston
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA
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22
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McGraw KL, Fuhler GM, Johnson JO, Clark JA, Caceres GC, Sokol L, List AF. Erythropoietin receptor signaling is membrane raft dependent. PLoS One 2012; 7:e34477. [PMID: 22509308 PMCID: PMC3317978 DOI: 10.1371/journal.pone.0034477] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 03/05/2012] [Indexed: 01/30/2023] Open
Abstract
Upon erythropoietin (Epo) engagement, Epo-receptor (R) homodimerizes to activate JAK2 and Lyn, which phosphorylate STAT5. Although recent investigations have identified key negative regulators of Epo-R signaling, little is known about the role of membrane localization in controlling receptor signal fidelity. Here we show a critical role for membrane raft (MR) microdomains in creation of discrete signaling platforms essential for Epo-R signaling. Treatment of UT7 cells with Epo induced MR assembly and coalescence. Confocal microscopy showed that raft aggregates significantly increased after Epo stimulation (mean, 4.3±1.4(SE) vs. 25.6±3.2 aggregates/cell; p≤0.001), accompanied by a >3-fold increase in cluster size (p≤0.001). Raft fraction immunoblotting showed Epo-R translocation to MR after Epo stimulation and was confirmed by fluorescence microscopy in Epo stimulated UT7 cells and primary erythroid bursts. Receptor recruitment into MR was accompanied by incorporation of JAK2, Lyn, and STAT5 and their activated forms. Raft disruption by cholesterol depletion extinguished Epo induced Jak2, STAT5, Akt and MAPK phosphorylation in UT7 cells and erythroid progenitors. Furthermore, inhibition of the Rho GTPases Rac1 or RhoA blocked receptor recruitment into raft fractions, indicating a role for these GTPases in receptor trafficking. These data establish a critical role for MR in recruitment and assembly of Epo-R and signal intermediates into discrete membrane signaling units.
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Affiliation(s)
- Kathy L. McGraw
- Department of Malignant Hematology, H. Lee Moffitt Cancer Center, Tampa, Florida, United States of America
- Cancer Biology Ph.D. Program, University of South Florida, Tampa, Florida, United States of America
| | - Gwenny M. Fuhler
- Department of Gasteroenterology and Hepatology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Joseph O. Johnson
- Analytic Microscopy Core Facility, H. Lee Moffitt Cancer Center, Tampa, Florida, United States of America
| | - Justine A. Clark
- Department of Malignant Hematology, H. Lee Moffitt Cancer Center, Tampa, Florida, United States of America
| | - Gisela C. Caceres
- Department of Malignant Hematology, H. Lee Moffitt Cancer Center, Tampa, Florida, United States of America
| | - Lubomir Sokol
- Department of Malignant Hematology, H. Lee Moffitt Cancer Center, Tampa, Florida, United States of America
| | - Alan F. List
- Department of Malignant Hematology, H. Lee Moffitt Cancer Center, Tampa, Florida, United States of America
- * E-mail:
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23
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Tokumasu F, Ostera GR, Amaratunga C, Fairhurst RM. Modifications in erythrocyte membrane zeta potential by Plasmodium falciparum infection. Exp Parasitol 2012; 131:245-51. [PMID: 22459624 DOI: 10.1016/j.exppara.2012.03.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 03/02/2012] [Accepted: 03/09/2012] [Indexed: 11/16/2022]
Abstract
The zeta potential (ZP) is an electrochemical property of cell surfaces that is determined by the net electrical charge of molecules exposed at the surface of cell membranes. Membrane proteins contribute to the total net electrical charge of cell surfaces and can alter ZP through variation in their copy number and changes in their intermolecular interactions. Plasmodium falciparum extensively remodels its host red blood cell (RBC) membrane by placing 'knob'-like structures at the cell surface. Using an electrophoretic mobility assay, we found that the mean ZP of human RBCs was -15.7 mV. In RBCs infected with P. falciparum trophozoites ('iRBCs'), the mean ZP was significantly lower (-14.6 mV, p<0.001). Removal of sialic acid from the cell surface by neuraminidase treatment significantly decreased the ZP of both RBCs (-6.06 mV) and iRBCs (-4.64 mV). Parasite-induced changes in ZP varied by P. falciparum clone and the presence of knobs on the iRBC surface. Variations in ZP values were accompanied by altered binding of iRBCs to human microvascular endothelial cells (MVECs). These data suggest that parasite-derived knob proteins contribute to the ZP of iRBCs, and that electrostatic and hydrophobic interactions between iRBC and MVEC membranes are involved in cytoadherence.
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Affiliation(s)
- Fuyuki Tokumasu
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8132, USA.
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24
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Cruz LN, Juliano MA, Budu A, Juliano L, Holder AA, Blackman MJ, Garcia CR. Extracellular ATP triggers proteolysis and cytosolic Ca²⁺ rise in Plasmodium berghei and Plasmodium yoelii malaria parasites. Malar J 2012; 11:69. [PMID: 22420332 PMCID: PMC3358241 DOI: 10.1186/1475-2875-11-69] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 03/15/2012] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Plasmodium has a complex cell biology and it is essential to dissect the cell-signalling pathways underlying its survival within the host. METHODS Using the fluorescence resonance energy transfer (FRET) peptide substrate Abz-AIKFFARQ-EDDnp and Fluo4/AM, the effects of extracellular ATP on triggering proteolysis and Ca²⁺ signalling in Plasmodium berghei and Plasmodium yoelii malaria parasites were investigated. RESULTS The protease activity was blocked in the presence of the purinergic receptor blockers suramin (50 μM) and PPADS (50 μM) or the extracellular and intracellular calcium chelators EGTA (5 mM) and BAPTA/AM (25, 100, 200 and 500 μM), respectively for P. yoelii and P. berghei. Addition of ATP (50, 70, 200 and 250 μM) to isolated parasites previously loaded with Fluo4/AM in a Ca²⁺-containing medium led to an increase in cytosolic calcium. This rise was blocked by pre-incubating the parasites with either purinergic antagonists PPADS (50 μM), TNP-ATP (50 μM) or the purinergic blockers KN-62 (10 μM) and Ip5I (10 μM). Incubating P. berghei infected cells with KN-62 (200 μM) resulted in a changed profile of merozoite surface protein 1 (MSP1) processing as revealed by western blot assays. Moreover incubating P. berghei for 17 h with KN-62 (10 μM) led to an increase in rings forms (82% ± 4, n = 11) and a decrease in trophozoite forms (18% ± 4, n = 11). CONCLUSIONS The data clearly show that purinergic signalling modulates P. berghei protease(s) activity and that MSP1 is one target in this pathway.
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Affiliation(s)
- Laura Nogueira Cruz
- Department of Physiology, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, Butantan, 05508-900 São Paulo, SP Brazil
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25
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Abstract
Bartonella spp. are facultative intracellular pathogens that employ a unique stealth infection strategy comprising immune evasion and modulation, intimate interaction with nucleated cells, and intraerythrocytic persistence. Infections with Bartonella are ubiquitous among mammals, and many species can infect humans either as their natural host or incidentally as zoonotic pathogens. Upon inoculation into a naive host, the bartonellae first colonize a primary niche that is widely accepted to involve the manipulation of nucleated host cells, e.g., in the microvasculature. Consistently, in vitro research showed that Bartonella harbors an ample arsenal of virulence factors to modulate the response of such cells, gain entrance, and establish an intracellular niche. Subsequently, the bacteria are seeded into the bloodstream where they invade erythrocytes and give rise to a typically asymptomatic intraerythrocytic bacteremia. While this course of infection is characteristic for natural hosts, zoonotic infections or the infection of immunocompromised patients may alter the path of Bartonella and result in considerable morbidity. In this review we compile current knowledge on the molecular processes underlying both the infection strategy and pathogenesis of Bartonella and discuss their connection to the clinical presentation of human patients, which ranges from minor complaints to life-threatening disease.
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Affiliation(s)
- Alexander Harms
- Focal Area Infection Biology, Biozentrum, University of Basel, Switzerland
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26
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Urbanus SL, Ott T. Plasticity of plasma membrane compartmentalization during plant immune responses. FRONTIERS IN PLANT SCIENCE 2012; 3:181. [PMID: 22876256 PMCID: PMC3411101 DOI: 10.3389/fpls.2012.00181] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 07/23/2012] [Indexed: 05/10/2023]
Abstract
Plasma membranes require high levels of plasticity to modulate the perception and transduction of extracellular and intracellular signals. Dynamic lateral assembly of protein complexes combined with an independent compositional lipid patterning in both membrane leaflets provide cells the opportunity to decorate this interface with specific proteins in an organized but dynamic manner. Such ability to dynamically reorganize the protein content of the plasma membrane is essential for the regulation of processes such as polarity of transport, development, and microbial infection. While the plant cell wall represents the first physical and mostly unspecific barrier for invading microbes, the plasma membrane is at the forefront of microbial recognition and initiation of defense responses. Accumulating evidence indicating dynamic compartmentalization of plasma membranes in response to environmental cues has increased the interest in the compositional heterogeneity of this bilayer. Here, we elucidate the recruitment of specific proteins into defined membrane structures that ensure functional compartmentalization of the bilayer during infection processes.
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Affiliation(s)
| | - Thomas Ott
- *Correspondence: Thomas Ott, Institute of Genetics, University of Munich, Großhaderner Str. 2-4, 82152 Martinsried, Germany. e-mail:
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27
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Fontaine A, Bourdon S, Belghazi M, Pophillat M, Fourquet P, Granjeaud S, Torrentino-Madamet M, Rogier C, Fusai T, Almeras L. Plasmodium falciparum infection-induced changes in erythrocyte membrane proteins. Parasitol Res 2011; 110:545-56. [PMID: 21744020 DOI: 10.1007/s00436-011-2521-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 06/22/2011] [Indexed: 01/08/2023]
Abstract
Over the past decade, advances in proteomic and mass spectrometry techniques and the sequencing of the Plasmodium falciparum genome have led to an increasing number of studies regarding the parasite proteome. However, these studies have focused principally on parasite protein expression, neglecting parasite-induced variations in the host proteome. Here, we investigated P. falciparum-induced modifications of the infected red blood cell (iRBC) membrane proteome, taking into account both host and parasite proteome alterations. Furthermore, we also determined if some protein changes were associated with genotypically distinct P. falciparum strains. Comparison of host membrane proteomes between iRBCs and uninfected red blood cells using fluorescence-based proteomic approaches, such as 2D difference gel electrophoresis revealed that more than 100 protein spots were highly up-represented (fold change increase greater than five) following P. falciparum infection for both strains (i.e. RP8 and Institut Pasteur Pregnancy Associated Malaria). The majority of spots identified by mass spectrometry corresponded to Homo sapiens proteins. However, infection-induced changes in host proteins did not appear to affect molecules located at the outer surface of the plasma membrane. The under-representation of parasite proteins could not be attributed to deficient parasite protein expression. Thus, this study describes for the first time that considerable host protein modifications were detected following P. falciparum infection at the erythrocyte membrane level. Further analysis of infection-induced host protein modifications will improve our knowledge of malaria pathogenesis.
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Affiliation(s)
- Albin Fontaine
- Unité de Parasitologie, Institut de Recherche Biomédicale des Armées (IRBA), antenne Marseille, IFR48, Allée du Médecin colonel Eugène Jamot, Parc du Pharo, BP 60 109, 13262, Marseille Cedex 07, France
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28
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Zuccala ES, Baum J. Cytoskeletal and membrane remodelling during malaria parasite invasion of the human erythrocyte. Br J Haematol 2011; 154:680-9. [DOI: 10.1111/j.1365-2141.2011.08766.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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29
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Preté PSC, Domingues CC, Meirelles NC, Malheiros SVP, Goñi FM, de Paula E, Schreier S. Multiple stages of detergent-erythrocyte membrane interaction--a spin label study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:164-70. [PMID: 21040698 DOI: 10.1016/j.bbamem.2010.10.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 09/15/2010] [Accepted: 10/26/2010] [Indexed: 10/18/2022]
Abstract
The various stages of the interaction between the detergent Triton X-100 (TTX-100) and membranes of whole red blood cells (RBC) were investigated in a broad range of detergent concentrations. The interaction was monitored by RBC hemolysis-assessed by release of intracellular hemoglobin (Hb) and inorganic phosphate-and by analysis of EPR spectra of a fatty acid spin probe intercalated in whole RBC suspensions, as well as pellets and supernatants obtained upon centrifugation of detergent-treated cells. Hemolysis finished at ca. 0.9mM TTX-100. Spectral analysis and calculation of order parameters (S) indicated that a complex sequence of events takes place, and allowed the characterization of various structures formed in the different stages of detergent-membrane interaction. Upon reaching the end of cell lysis, essentially no pellet was detected, the remaining EPR signal being found almost entirely in the supernatants. Calculated order parameters revealed that whole RBC suspensions, pellets, and supernatants possessed a similar degree of molecular packing, which decreased to a small extent up to 2.5mM detergent. Between 3.2 and 10mM TTX-100, a steep decrease in S was observed for both whole RBC suspensions and supernatants. Above 10mM detergent, S decreased in a less pronounced manner and the EPR spectra approached that of pure TTX-100 micelles. The data were interpreted in terms of the following events: at the lower detergent concentrations, an increase in membrane permeability occurs; the end of hemolysis coincides with the lack of pellet upon centrifugation. Up to 2.5mM TTX-100 the supernatants consist of a (very likely) heterogeneous population of membrane fragments with molecular packing similar to that of whole cells. As the detergent concentration increases, mixed micelles are formed containing lipid and/or protein, approaching the packing found in pure TTX-100 micelles. This analysis is in agreement with the models proposed by Lasch (Biochim. Biophys Acta 1241 (1995) 269-292) and by Le Maire and coworkers (Biochim. Biophys. Acta 1508 (2000) 86-111).
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Affiliation(s)
- Paulo S C Preté
- Department of Biochemistry, Institute of Biology, State University of Campinas, SP, Brazil
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30
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Déchamps S, Shastri S, Wengelnik K, Vial HJ. Glycerophospholipid acquisition in Plasmodium - a puzzling assembly of biosynthetic pathways. Int J Parasitol 2010; 40:1347-65. [PMID: 20600072 DOI: 10.1016/j.ijpara.2010.05.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2010] [Revised: 05/24/2010] [Accepted: 05/25/2010] [Indexed: 01/06/2023]
Abstract
Throughout the Plasmodium life cycle, malaria parasites repeatedly undergo rapid cellular growth and prolific divisions, necessitating intense membrane neogenesis and, in particular, the acquisition of high amounts of phospholipids. At the intraerythrocytic stage, glycerophospholipids are the main parasite membrane constituents, which mostly originate from the Plasmodium-encoded enzymatic machinery. Several proteins and entire pathways have been characterized and their features reported, thereby generating a global view of glycerophospholipid synthesis across Plasmodium spp. The malaria parasite displays a panoply of pathways that are seldom found together in a single organism. The major glycerophospholipids are synthesized via ancestral prokaryotic CDP-diacylglycerol-dependent pathways and eukaryotic-type de novo pathways. The parasite exhibits additional reactions that bridge some of these routes and are otherwise restricted to some organisms, such as plants, while base-exchange mechanisms are largely unexplored in Plasmodium. Marked differences between Plasmodium spp. have also been reported in phosphatidylcholine and phosphatidylethanolamine synthesis. Little is currently known about glycerophospholipid acquisition at non-erythrocytic stages, but recent data reveal that intrahepatocytic parasites, oocysts and sporozoites import various host lipids, and that de novo fatty acid synthesis is only crucial at the late liver stage. More studies on the different Plasmodium developmental stages are needed, to further assemble the different pieces of this glycerophospholipid synthesis puzzle, which contains highly promising therapeutic targets.
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Affiliation(s)
- Sandrine Déchamps
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR 5235, Centre National de la Recherche Scientifique (CNRS) - Universite Montpellier 2, cc 107, Place Eugene Bataillon, 34095 Montpellier Cedex 05, France
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31
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Shastri S, Zeeman AM, Berry L, Verburgh RJ, Braun-Breton C, Thomas AW, Gannoun-Zaki L, Kocken CHM, Vial HJ. Plasmodium CDP-DAG synthase: an atypical gene with an essential N-terminal extension. Int J Parasitol 2010; 40:1257-68. [PMID: 20385136 DOI: 10.1016/j.ijpara.2010.03.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 03/10/2010] [Accepted: 03/10/2010] [Indexed: 10/19/2022]
Abstract
Cytidine diphosphate diacylglycerol synthase (CDS) diverts phosphatidic acid towards the biosynthesis of CDP-DAG, an obligatory liponucleotide intermediate in anionic phospholipid biosynthesis. The 78kDa predicted Plasmodium falciparum CDS (PfCDS) is recovered as a 50 kDa conserved C-terminal cytidylyltransferase domain (C-PfCDS) and a 28kDa fragment that corresponds to the unusually long hydrophilic asparagine-rich N-terminal extension (N-PfCDS). Here, we show that the two fragments of PfCDS are the processed forms of the 78 kDa pro-form that is encoded from a single transcript with no alternate translation start site for C-PfCDS. PfCDS, which shares 54% sequence identity with Plasmodium knowlesi CDS (PkCDS), could substitute for PkCDS in P. knowlesi. Experiments to disrupt either the full-length or the N-terminal extension of PkCDS indicate that not only the C-terminal cytidylyltransferase domain but also the N-terminal extension is essential to Plasmodium spp. PkCDS and PfCDS introduced in P. knowlesi were processed in the parasite, suggesting a conserved parasite-dependent mechanism. The N-PfCDS appears to be a peripheral membrane protein and is trafficked outside the parasite to the parasitophorous vacuole. Although the function of this unusual N-PfCDS remains enigmatic, the study here highlights features of this essential gene and its biological importance during the intra-erythrocytic cycle of the parasite.
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Affiliation(s)
- Shilpa Shastri
- CNRS UMR5235, University of Montpellier 2, Place Eugene Bataillon, 34095 Montpellier Cedex 5, France
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Vieira FS, Corrêa G, Einicker-Lamas M, Coutinho-Silva R. Host-cell lipid rafts: a safe door for micro-organisms? Biol Cell 2010; 102:391-407. [PMID: 20377525 PMCID: PMC7161784 DOI: 10.1042/bc20090138] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 02/10/2010] [Indexed: 12/20/2022]
Abstract
The lipid raft hypothesis proposed that these microdomains are small (10-200 nM), highly dynamic and enriched in cholesterol, glycosphingolipids and signalling phospholipids, which compartmentalize cellular processes. These membrane regions play crucial roles in signal transduction, phagocytosis and secretion, as well as pathogen adhesion/interaction. Throughout evolution, many pathogens have developed mechanisms to escape from the host immune system, some of which are based on the host membrane microdomain machinery. Thus lipid rafts might be exploited by pathogens as signalling and entry platforms. In this review, we summarize the role of lipid rafts as players in the overall invasion process used by different pathogens to escape from the host immune system.
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Affiliation(s)
- Flávia Sarmento Vieira
- Laboratório de Imunofisiologia, Universidade Federal do Rio de Janeiro, Instituto de Biofísica Carlos Chagas Filho, CCS, Rio de Janeiro, RJ, Brazil
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Baumeister S, Winterberg M, Przyborski JM, Lingelbach K. The malaria parasite Plasmodium falciparum: cell biological peculiarities and nutritional consequences. PROTOPLASMA 2010; 240:3-12. [PMID: 19949823 DOI: 10.1007/s00709-009-0090-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 11/09/2009] [Indexed: 05/28/2023]
Abstract
Apicomplexan parasites obligatorily invade and multiply within eukaryotic cells. Phylogenetically, they are related to a group of algae which, during their evolution, have acquired a secondary endosymbiont. This organelle, which in the parasite is called the apicoplast, is highly reduced compared to the endosymbionts of algae, but still contains many plant-specific biosynthetic pathways. The malaria parasite Plasmodium falciparum infects mammalian erythrocytes which are devoid of intracellular compartments and which largely lack biosynthetic pathways. Despite the limited resources of nutrition, the parasite grows and generates up to 32 merozoites which are the infectious stages of the complex life cycle. A large part of the intra-erythrocytic development takes place in the so-called parasitophorous vacuole, a compartment which forms an interface between the parasite and the cytoplasm of the host cell. In the course of parasite growth, the host cell undergoes dramatic alterations which on one hand contribute directly to the symptoms of severe malaria and which, on the other hand, are also required for parasite survival. Some of these alterations facilitate the acquisition of nutrients from the extracellular environment which are not provided by the host cell. Here, we describe the cell biologically unique interactions between an intracellular eukaryotic pathogen and its metabolically highly reduced host cell. We further discuss current models to explain the appearance of pathogen-induced novel physiological properties in a host cell which has lost its genetic programme.
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Affiliation(s)
- Stefan Baumeister
- Department of Parasitology, Faculty of Biology, Philipps Universität, Marburg, Germany
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Azouzi S, El Kirat K, Morandat S. The potent antimalarial drug cyclosporin A preferentially destabilizes sphingomyelin-rich membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:1960-1965. [PMID: 19697916 DOI: 10.1021/la902580w] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Cyclosporin A (CsA) is a hydrophobic cyclic peptide produced by a fungus. CsA is widely used as an immunosuppressive agent to inhibit the rejection of transplanted organs. CsA also exhibits an antiparasitic activity against Plasmodium, the microorganism responsible for malaria disease. This antimalarial activity is not completely understood yet. In this study, we have used Langmuir monolayers and atomic force microscopy to investigate the interaction of CsA with different lipids: phosphatidylcholines with different molecular packing, cholesterol, and sphingomyelin. We have shown that CsA inserts in all kinds of lipid monolayers but it has a marked preference for sphingomyelin monolayers. This preferential insertion of CsA within sphingomyelin-enriched membranes could explain the antimalarial activity of CsA. Indeed, the parasites need to produce a membrane network inside the erythrocytes, which allows for their proper development/multiplication by exchanging nutrients with the external medium. This membrane network is particularly enriched in sphingomyelin, so the preferential insertion of CsA in these bilayers may destabilize them, thereby inhibiting the development of the parasite.
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Affiliation(s)
- Slim Azouzi
- Laboratoire de Génie Enzymatique et Cellulaire, CNRS UMR 6022, 60205 Compiègne Cedex, France
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Tull D, Naderer T, Spurck T, Mertens HDT, Heng J, McFadden GI, Gooley PR, McConville MJ. Membrane protein SMP-1 is required for normal flagellum function in Leishmania. J Cell Sci 2010; 123:544-54. [PMID: 20086045 DOI: 10.1242/jcs.059097] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Eukaryotic flagella and cilia are surrounded by a membrane that is continuous with, but distinct from, the rest of the plasma membrane. In Leishmania parasites, the inner leaflet of the flagellar membrane is coated with the acylated membrane protein, SMP-1. Here, we provide evidence that SMP-1 stabilizes the flagellar membrane and is required for flagella elongation and function. The expression and flagella targeting of SMP-1 is tightly associated with flagella elongation during amastigote to promastigote differentiation. Deletion of the genes encoding SMP-1 and the flagellar pocket protein SMP-2, led to the production of short flagella and defects in motility. Alterations in the physical properties of the smp-1/smp-2(-/-) flagellar membrane were suggested by: (1) the accumulation of membrane vesicles in the flagellar matrix, and (2) further retraction of flagella following partial inhibition of sterol and sphingolipid biosynthesis. The flagella phenotype of the smp-1/smp-2(-/-) null mutant was reversed by re-expression of SMP-1, but not SMP-2. SMP-1 contains a jelly-roll beta-sheet structure that is probably conserved in all SMP proteins, and forms stable homo-oligomers in vivo. We propose that the SMP-1 coat generates and/or stabilizes sterol- and sphingolipid-rich domains in the flagellar membrane.
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Affiliation(s)
- Dedreia Tull
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
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Pasini EM, Lutz HU, Mann M, Thomas AW. Red Blood Cell (RBC) membrane proteomics — Part II: Comparative proteomics and RBC patho-physiology. J Proteomics 2010; 73:421-35. [DOI: 10.1016/j.jprot.2009.07.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 07/07/2009] [Accepted: 07/13/2009] [Indexed: 12/23/2022]
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Abstract
SUMMARYThe invasive blood stage of malaria parasites, merozoites, are complex entities specialized for the capture and entry of red blood cells. Their potential for vaccination and other anti-malaria strategies have attracted much research attention over the last 40 years, and there is now a considerable body of data relating to their biology. In this article some of the major advances over this period and remaining challenges are reviewed.
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Resistance of Human Erythrocyte Membranes to Triton X-100 and C12E8. J Membr Biol 2008; 227:39-48. [DOI: 10.1007/s00232-008-9142-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Accepted: 11/11/2008] [Indexed: 11/24/2022]
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Abstract
Mycoplasma suis belongs to the hemotrophic mycoplasma group and causes infectious anemia in pigs. According to the present state of knowledge, this organism adheres to the surface of erythrocytes but does not invade them. We found a novel M. suis isolate that caused severe anemia in pigs with a fatal disease course. Interestingly, only marginal numbers of the bacteria were visible on and between the erythrocytes in acridine orange-stained blood smears for acutely diseased pigs, whereas very high loads of M. suis were detected in the same blood samples by quantitative PCR. These findings indicated that M. suis is capable of invading erythrocytes. By use of fluorescent labeling of M. suis and examination by confocal laser scanning microscopy, as well as scanning and transmission electron microscopy, we proved that the localization of M. suis was intracellular. This organism invades erythrocytes in an endocytosis-like process and is initially surrounded by two membranes, and it was also found floating freely in the cytoplasm. In conclusion, we were able to prove for the first time that a member of the hemotrophic mycoplasma group is able to invade the erythrocytes of its host. Such colonization should protect the bacterial cells from the host's immune response and hamper antibiotic treatment. In addition, an intracellular life cycle may explain the chronic nature of hemotrophic mycoplasma infections and should serve as the foundation for novel strategies in hemotrophic mycoplasma research (e.g., treatment or prophylaxis).
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Cesbron-Delauw MF, Gendrin C, Travier L, Ruffiot P, Mercier C. Apicomplexa in mammalian cells: trafficking to the parasitophorous vacuole. Traffic 2008; 9:657-64. [PMID: 18315533 DOI: 10.1111/j.1600-0854.2008.00728.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Most Apicomplexa reside and multiply in the cytoplasm of their host cell, within a parasitophorous vacuole (PV) originating from both parasite and host cell components. Trafficking of parasite-encoded proteins destined to membrane compartments beyond the confine of the parasite plasma membrane is a process that offers a rich territory to explore novel mechanisms of protein-membrane interactions. Here, we focus on the PVs formed by the asexual stages of two pathogens of medical importance, Plasmodium and Toxoplasma. We compare the PVs of both parasites, with a particular emphasis on their evolutionary divergent compartmentalization within the host cell. We also discuss the existence of peculiar export mechanisms and/or sorting determinants that are potentially involved in the post-secretory targeting of parasite proteins to the PV subcompartments.
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Affiliation(s)
- Marie-France Cesbron-Delauw
- Laboratoire Adaptation et Pathogénie des Microorganismes, CNRS UMR 5163, Université Joseph Fourier - Grenoble 1, BP 170, 38042 Grenoble Cedex 9, France.
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Sherman IW. References. ADVANCES IN PARASITOLOGY 2008. [DOI: 10.1016/s0065-308x(08)00430-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Maurer's clefts of Plasmodium falciparum are secretory organelles that concentrate virulence protein reporters for delivery to the host erythrocyte. Blood 2007; 111:2418-26. [PMID: 18057226 PMCID: PMC2234068 DOI: 10.1182/blood-2007-09-115279] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In blood-stage infection by the human malaria parasite Plasmodium falciparum, export of proteins from the intracellular parasite to the erythrocyte is key to virulence. This export is mediated by a host-targeting (HT) signal present on a “secretome” of hundreds of parasite proteins engaged in remodeling the erythrocyte. However, the route of HT-mediated export is poorly understood. Here we show that minimal soluble and membrane protein reporters that contain the HT motif and mimic export of endogenous P falciparum proteins are detected in the lumen of “cleft” structures synthesized by the pathogen. Clefts are efficiently targeted by the HT signal. Furthermore, the HT signal does not directly translocate across the parasitophorous vacuolar membrane (PVM) surrounding the parasite to deliver protein to the erythrocyte cytoplasm, as suggested by current models of parasite protein trafficking to the erythrocyte. Rather, it is a lumenal signal that sorts protein into clefts, which then are exported beyond the PVM. These data suggest that Maurer's clefts, which are unique to the virulent P falciparum species, are pathogen-induced secretory organelles that concentrate HT-containing soluble and membrane parasite proteins in their lumen for delivery to the host erythrocyte.
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