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Coelho FS, Oliveira MM, Vieira DP, Torres PHM, Moreira ICF, Martins-Duarte ES, Gonçalves IC, Cabanelas A, Pascutti PG, Fragoso SP, Lopes AH. A novel receptor for platelet-activating factor and lysophosphatidylcholine in Trypanosoma cruzi. Mol Microbiol 2021; 116:890-908. [PMID: 34184334 DOI: 10.1111/mmi.14778] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 06/24/2021] [Accepted: 06/26/2021] [Indexed: 01/12/2023]
Abstract
The lipid mediators, platelet-activating factor (PAF) and lysophosphatidylcholine (LPC), play relevant pathophysiological roles in Trypanosoma cruzi infection. Several species of LPC, including C18:1 LPC, which mimics the effects of PAF, are synthesized by T. cruzi. The present study identified a receptor in T. cruzi, which was predicted to bind to PAF, and found it to be homologous to members of the progestin and adiponectin family of receptors (PAQRs). We constructed a three-dimensional model of the T. cruzi PAQR (TcPAQR) and performed molecular docking to predict the interactions of the TcPAQR model with C16:0 PAF and C18:1 LPC. We knocked out T. cruzi PAQR (TcPAQR) gene and confirmed the identity of the expressed protein through immunoblotting and immunofluorescence assays using an anti-human PAQR antibody. Wild-type and knockout (KO) parasites were also used to investigate the in vitro cell differentiation and interactions with peritoneal mouse macrophages; TcPAQR KO parasites were unable to react to C16:0 PAF or C18:1 LPC. Our data are highly suggestive that PAF and LPC act through TcPAQR in T. cruzi, triggering its cellular differentiation and ability to infect macrophages.
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Affiliation(s)
- Felipe S Coelho
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Mauricio M Oliveira
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Pedro H M Torres
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Isabel C F Moreira
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Erica S Martins-Duarte
- Departmento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Inês C Gonçalves
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Adriana Cabanelas
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Pedro G Pascutti
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Stenio P Fragoso
- Laboratório de Biologia Molecular e Sistêmica de Tripanossomatídeos, Instituto Carlos Chagas, Curitiba, Brazil
| | - Angela H Lopes
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Lysophosphatidylcholine triggers cell differentiation in the protozoan parasite Herpetomonas samuelpessoai through the CK2 pathway. Acta Parasitol 2020; 65:108-117. [PMID: 31755068 DOI: 10.2478/s11686-019-00135-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 10/03/2019] [Indexed: 12/30/2022]
Abstract
BACKGROUND Protozoa are distantly related to vertebrates but present some features of higher eukaryotes, making them good model systems for studying the evolution of basic processes such as the cell cycle. Herpetomonas samuelpessoai is a trypanosomatid parasite isolated from the hemipteran insect Zelus leucogrammus. Lysophosphatidylcholine (LPC) is implicated in the transmission and establishment of Chagas disease, whose etiological agent is Trypanosoma cruzi. LPC is synthesized by T. cruzi and its vectors, the hemipteran Rhodnius prolixus and Triatoma infestans. Platelet-activating factor (PAF), a phospholipid with potent and diverse physiological and pathophysiological actions, is a powerful inducer of cell differentiation in Herpetomonas muscarum muscarum and T. cruzi. The enzyme phospholipase A2 (PLA2) catalyzes the hydrolysis of the 2-ester bond of 3-sn-phosphoglyceride, transforming phosphatidylcholine (PC) into LPC. METHODS In this study, we evaluated cellular differentiation, PLA2 activity and protein kinase CK2 activity of H. samuelpessoai in the absence and in the presence of LPC and PAF. RESULTS We demonstrate that both PC and LPC promoted a twofold increase in the cellular differentiation of H. samuelpessoai, through CK2, with a concomitant inhibition of its cell growth. Intrinsic PLA2 most likely directs this process by converting PC into LPC. CONCLUSIONS Our results suggest that the actions of LPC on H. samuelpessoai occur upon binding to a putative PAF receptor and that the protein kinase CK2 plays a major role in this process. Cartoon depicting a model for the synthesis and functions of LPC in Herpetomonas samuelpessoai, based upon our results regarding the role of LPC on the cell biology of Trypanosoma cruzi [28-32]. N nucleus, k kinetoplast, PC phosphatidylcholine, LPC lysophosphatidylcholine, PLA2 phospholipase A2, PAFR putative PAF receptor in trypanosomatids [65], CK2 protein kinase CK2 [16].
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3
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Borges AF, Morato CI, Gomes RS, Dorta ML, de Oliveira MAP, Ribeiro-Dias F. Platelet-activating factor increases reactive oxygen species-mediated microbicidal activity of human macrophages infected with Leishmania (Viannia) braziliensis. Pathog Dis 2017; 75:3983173. [DOI: 10.1093/femspd/ftx082] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 07/19/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- Arissa Felipe Borges
- Instituto de Patologia Tropical e Saúde Pública, Universidade Federal Goiás, Goiânia, Goiás, Rua 235 S/N, Setor Leste Universitário, Goiânia - GO 74605-050, Brazil
| | - Camila Imai Morato
- Instituto de Patologia Tropical e Saúde Pública, Universidade Federal Goiás, Goiânia, Goiás, Rua 235 S/N, Setor Leste Universitário, Goiânia - GO 74605-050, Brazil
| | - Rodrigo Saar Gomes
- Instituto de Patologia Tropical e Saúde Pública, Universidade Federal Goiás, Goiânia, Goiás, Rua 235 S/N, Setor Leste Universitário, Goiânia - GO 74605-050, Brazil
| | - Miriam Leandro Dorta
- Instituto de Patologia Tropical e Saúde Pública, Universidade Federal Goiás, Goiânia, Goiás, Rua 235 S/N, Setor Leste Universitário, Goiânia - GO 74605-050, Brazil
| | - Milton Adriano Pelli de Oliveira
- Instituto de Patologia Tropical e Saúde Pública, Universidade Federal Goiás, Goiânia, Goiás, Rua 235 S/N, Setor Leste Universitário, Goiânia - GO 74605-050, Brazil
| | - Fátima Ribeiro-Dias
- Instituto de Patologia Tropical e Saúde Pública, Universidade Federal Goiás, Goiânia, Goiás, Rua 235 S/N, Setor Leste Universitário, Goiânia - GO 74605-050, Brazil
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Gangalum PR, de Castro W, Vieira LQ, Dey R, Rivas L, Singh S, Majumdar S, Saha B. Platelet-Activating Factor Receptor Contributes to Antileishmanial Function of Miltefosine. THE JOURNAL OF IMMUNOLOGY 2015; 194:5961-7. [DOI: 10.4049/jimmunol.1401890] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 03/30/2015] [Indexed: 11/19/2022]
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Pawlowic MC, Zhang K. Leishmania parasites possess a platelet-activating factor acetylhydrolase important for virulence. Mol Biochem Parasitol 2012; 186:11-20. [PMID: 22954769 DOI: 10.1016/j.molbiopara.2012.08.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 08/20/2012] [Accepted: 08/21/2012] [Indexed: 01/03/2023]
Abstract
Leishmania parasites are intracellular protozoans capable of salvaging and remodeling lipids from the host. To understand the role of lipid metabolism in Leishmania virulence, it is necessary to characterize the enzymes involved in the uptake and turnover of phospholipids. This study focuses on a putative phospholipase A2 (PLA2)/platelet-activating factor acetylhydrolase (PAF-AH) in Leishmania major. In mammals, PAF-AH is a subgroup of PLA2 catalyzing the hydrolysis/inactivation of platelet-activating factor (PAF), a potent mediator of many leukocyte functions. By immunofluorescence microscopy, L. major PLA2/PAF-AH is predominantly localized in the ER. While wild type L. major parasites are able to hydrolyze PAF, this activity is completely absent in the PLA2/PAF-AH-null mutants. Meanwhile, deletion of PLA2/PAF-AH had no significant effect on the turnover of common glycerophospholipids such as phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylglycerol. PLA2/PAF-AH is not required for the growth of L. major parasites in culture, or the production of GPI-anchored virulence factors. Nonetheless, it does play a key role in the mammalian host as the PLA2/PAF-AH null mutants exhibit attenuated virulence in BALB/c mice. In conclusion, these data suggest that Leishmania parasites possess a functional PAF-AH and the degradation of PAF or PAF-like lipids is an important step in infection.
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Affiliation(s)
- Mattie C Pawlowic
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
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Azevedo E, Oliveira LT, Castro Lima AK, Terra R, Dutra PML, Salerno VP. Interactions between Leishmania braziliensis and Macrophages Are Dependent on the Cytoskeleton and Myosin Va. J Parasitol Res 2012; 2012:275436. [PMID: 22792440 PMCID: PMC3391898 DOI: 10.1155/2012/275436] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 05/06/2012] [Accepted: 05/07/2012] [Indexed: 11/18/2022] Open
Abstract
Leishmaniasis is a neglected tropical disease with no effective vaccines. Actin, microtubules and the actin-based molecular motor myosin Va were investigated for their involvement in Leishmania braziliensis macrophage interactions. Results showed a decrease in the association index when macrophages were without F-actin or microtubules regardless of the activation state of the macrophage. In the absence of F-actin, the production of NO in non-activated cells increased, while in activated cells, the production of NO was reduced independent of parasites. The opposite effect of an increased NO production was observed in the absence of microtubules. In activated cells, the loss of cytoskeletal components inhibited the release of IL-10 during parasite interactions. The production of IL-10 also decreased in the absence of actin or microtubules in non-activated macrophages. Only the disruption of actin altered the production of TNF-α in activated macrophages. The expression of myosin Va tail resulted in an acute decrease in the association index between transfected macrophages and L. braziliensis promastigotes. These data reveal the importance of F-actin, microtubules, and myosin-Va suggesting that modulation of the cytoskeleton may be a mechanism used by L. braziliensis to overcome the natural responses of macrophages to establish infections.
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Affiliation(s)
- Elisama Azevedo
- Laboratório de Imunologia e Bioquímica de Protozoários, Departamento de Microbiologia, Imunologia e Parasitologia, FCM, UERJ, Avenida Professor Manuel de Abreu 444 5° andar. Vila Isabel, 20550-170 Rio de Janeiro, RJ, Brazil
- Programa de Pós-Graduação em Microbiologia Médica, Faculdade de Ciências Médicas, UERJ, 20550-170 Rio de Janerio, RJ, Brazil
| | - Leandro Teixeira Oliveira
- Departamento Biociências, Escola de Educação Física e Desportos, Universidade Federal do Rio de Janeiro, 21941-599 Rio de Janerio, RJ, Brazil
| | - Ana Karina Castro Lima
- Laboratório de Imunologia e Bioquímica de Protozoários, Departamento de Microbiologia, Imunologia e Parasitologia, FCM, UERJ, Avenida Professor Manuel de Abreu 444 5° andar. Vila Isabel, 20550-170 Rio de Janeiro, RJ, Brazil
- Programa de Pós-Graduação em Microbiologia Médica, Faculdade de Ciências Médicas, UERJ, 20550-170 Rio de Janerio, RJ, Brazil
| | - Rodrigo Terra
- Laboratório de Imunologia e Bioquímica de Protozoários, Departamento de Microbiologia, Imunologia e Parasitologia, FCM, UERJ, Avenida Professor Manuel de Abreu 444 5° andar. Vila Isabel, 20550-170 Rio de Janeiro, RJ, Brazil
- Programa de Pós-Graduação em Biodinâmica do Movimento, EEFD, UFRJ, 21941-599 Rio de Janerio, RJ, Brazil
| | - Patrícia Maria Lourenço Dutra
- Laboratório de Imunologia e Bioquímica de Protozoários, Departamento de Microbiologia, Imunologia e Parasitologia, FCM, UERJ, Avenida Professor Manuel de Abreu 444 5° andar. Vila Isabel, 20550-170 Rio de Janeiro, RJ, Brazil
| | - Verônica P. Salerno
- Departamento Biociências, Escola de Educação Física e Desportos, Universidade Federal do Rio de Janeiro, 21941-599 Rio de Janerio, RJ, Brazil
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Chatzovoulos P, Tsoupras A, Samiotaki M, Panayotou G, Demopoulos C, Dotsika E. Paf-Metabolic Enzymes and Paf-like Activity in L. Infantum and L. Major Promastigotes. EUR J INFLAMM 2011. [DOI: 10.1177/1721727x1100900303] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Leishmania spp are obligate intracellular protozoan parasites of the mononuclear phagocyte system that cause a spectrum of diseases known as leishmaniasis. Platelet Activating Factor (PAF) and some PAF-antagonists seem to play a key role in Leishmania infection. In this article we detected for the first time the specific activities of PAF basic metabolic enzymes, PAF cholinephosphotransferase (PAF-CPT) and Lyso-PAF-acetylotransferase (Lyso-PAF-AT), in two species of Leishmania, namely Leishmania major (L. major) and Leishmania infantum (L. infantum). Specific activity of PAF-CPT of L. major homogenates was substantially higher than that of L. infantum homogenates, while Lyso-PAF-AT specific activities of the homogenates of both species were detected in the same levels. In addition, PAF-like molecules were detected in cells and their culture medium of both species. These results show that PAF-biosynthesis exists and varies between Leishmania species, findings that are in correlation with the general idea that the presence of PAF in several Leishmania species is implicated in Leishmania infection.
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Affiliation(s)
- P. Chatzovoulos
- Faculty of Chemistry, National and Kapodistrian University of Athens, Athens
| | - A.B. Tsoupras
- Faculty of Chemistry, National and Kapodistrian University of Athens, Athens
| | - M. Samiotaki
- Protein Chemistry Laboratory B.S.R.C. “Alexander Fleming”, Vari, Athens
| | - G. Panayotou
- Protein Chemistry Laboratory B.S.R.C. “Alexander Fleming”, Vari, Athens
| | - C.A. Demopoulos
- Faculty of Chemistry, National and Kapodistrian University of Athens, Athens
| | - E. Dotsika
- Laboratory of Cellular Immunology, Hellenic Pasteur Institute, Athens, Greece
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8
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Effects of platelet-activating factor on the interaction of Trypanosoma cruzi with Rhodnius prolixus. Parasitol Res 2010; 108:1473-8. [DOI: 10.1007/s00436-010-2194-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Accepted: 11/26/2010] [Indexed: 10/18/2022]
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9
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Stimulation of Leishmania tropica protein kinase CK2 activities by platelet-activating factor (PAF). Acta Trop 2009; 111:247-54. [PMID: 19433049 DOI: 10.1016/j.actatropica.2009.05.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2008] [Revised: 03/29/2009] [Accepted: 05/05/2009] [Indexed: 11/23/2022]
Abstract
Leishmania tropica is one of the causative agents of cutaneous leishmaniasis. Platelet-activating factor (PAF) is a phospholipid mediator in diverse biological and pathophysiological processes. Here we show that PAF promoted a three-fold increase on ecto-protein kinase and a three-fold increase on the secreted kinase activity of L. tropica live promastigotes. When casein was added to the reaction medium, along with PAF, there was a four-fold increase on the ecto-kinase activity. When live L. tropica promastigotes were pre-incubated for 30 min in the presence of PAF-plus casein, a six-fold increase on the secreted kinase activity was observed. Also, a protein released from L. tropica promastigotes reacted with polyclonal antibodies for the mammalian CK2 alpha catalytic subunit. Furthermore, in vitro mouse macrophage infection by L. tropica was doubled when promastigotes were pre-treated for 2 h with PAF. Similar results were obtained when the interaction was performed in the presence of purified CK2 or casein. TBB and DRB, CK2 inhibitors, reversed PAF enhancement of macrophage infection by L. tropica. WEB 2086, a competitive PAF antagonist, reversed all PAF effects here described. This study shows for the first time that PAF promotes the activation of two isoforms of CK2, secreted and membrane-bound, correlating these activities to infection of mouse macrophages.
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10
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Mesquita RD, Carneiro AB, Bafica A, Gazos-Lopes F, Takiya CM, Souto-Padron T, Vieira DP, Ferreira-Pereira A, Almeida IC, Figueiredo RT, Porto BN, Bozza MT, Graça-Souza AV, Lopes AHCS, Atella GC, Silva-Neto MAC. Trypanosoma cruzi infection is enhanced by vector saliva through immunosuppressant mechanisms mediated by lysophosphatidylcholine. Infect Immun 2008; 76:5543-52. [PMID: 18794282 PMCID: PMC2583594 DOI: 10.1128/iai.00683-08] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 07/12/2008] [Accepted: 09/04/2008] [Indexed: 11/20/2022] Open
Abstract
Trypanosoma cruzi, the etiological agent of Chagas disease, is transmitted by bug feces deposited on human skin during a blood meal. However, parasite infection occurs through the wound produced by insect mouthparts. Saliva of the Triatominae bug Rhodnius prolixus is a source of lysophosphatidylcholine (LPC). Here, we tested the role of both triatomine saliva and LPC on parasite transmission. We show that vector saliva is a powerful inducer of cell chemotaxis. A massive number of inflammatory cells were found at the sites where LPC or saliva was inoculated into the skin of mice. LPC is a known chemoattractant for monocytes, but neutrophil recruitment induced by saliva is LPC independent. The preincubation of peritoneal macrophages with saliva or LPC increased fivefold the association of T. cruzi with these cells. Moreover, saliva and LPC block nitric oxide production by T. cruzi-exposed macrophages. The injection of saliva or LPC into mouse skin in the presence of the parasite induces an up-to-sixfold increase in blood parasitemia. Together, our data suggest that saliva of the Triatominae enhances T. cruzi transmission and that some of its biological effects are attributed to LPC. This is a demonstration that a vector-derived lysophospholipid may act as an enhancing factor of Chagas disease.
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Affiliation(s)
- Rafael D Mesquita
- Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, UFRJ, 21940-590, Rio de Janeiro, RJ, Brazil
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11
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Gomes MT, Monteiro RQ, Grillo LA, Leite-Lopes F, Stroeder H, Ferreira-Pereira A, Alviano CS, Barreto-Bergter E, Neto HCF, Cunha E Silva NL, Almeida IC, Soares RMA, Lopes AH. Platelet-activating factor-like activity isolated from Trypanosoma cruzi. Int J Parasitol 2006; 36:165-73. [PMID: 16337632 DOI: 10.1016/j.ijpara.2005.09.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Revised: 09/30/2005] [Accepted: 09/30/2005] [Indexed: 12/01/2022]
Abstract
Platelet-activating factor is a phospholipid mediator that exhibits a wide variety of physiological and pathophysiological effects, including induction of inflammatory response, chemotaxis and cellular differentiation. Trypanosoma cruzi, the etiological agent of Chagas' disease, is transmitted by triatomine insects and while in the triatomine midgut the parasite differentiates from a non-infective epimastigote stage into the pathogenic trypomastigote metacyclic form. We have previously demonstrated that platelet activating factor triggers in vitro cell differentiation of T. cruzi. Here we show a platelet activating factor-like activity isolated from lipid extract of T. cruzi epimastigotes incubated in the presence of [14C]acetate. Trypanosoma cruzi-platelet activating factor-like lipid induced the aggregation of rabbit platelets, which was prevented by platelet activating factor-acetylhydrolase. Mouse macrophage infection by T. cruzi was stimulated when epimastigotes were kept for 5 days in the presence of T. cruzi-platelet activating factor, before interacting with the macrophages. The differentiation of epimastigotes into metacyclic trypomastigotes was also triggered by T. cruzi-platelet activating factor. These effects were abrogated by a platelet activating factor antagonist, WEB 2086. Polyclonal antibody raised against mouse platelet activating factor receptor showed labelling for T. cruzi epimastigotes using immunoblotting and immunofluorescence assays. These data suggest that T. cruzi contain the components of an autocrine platelet activating factor-like ligand-receptor system that modulates cell differentiation towards the infectious stage.
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Affiliation(s)
- Marta T Gomes
- Instituto de Microbiologia, Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, Cidade Universitária, CCS, Bloco I, Ilha do Fundão, 21941-590 Rio de Janeiro, RJ, Brazil
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Silva-Neto MAC, Carneiro AB, Vieira DP, Mesquita RD, Lopes AHCS. Platelet-activating factor (PAF) activates casein kinase 2 in the protozoan parasite Herpetomonas muscarum muscarum. Biochem Biophys Res Commun 2002; 293:1358-63. [PMID: 12054663 DOI: 10.1016/s0006-291x(02)00395-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Herpetomonas muscarum muscarum is a flagellate parasite of the family Trypanosomatidae, whose cell differentiation can be triggered by the lipid mediator, PAF. In this study we demonstrate for the first time that PAF effect relies on the activation of casein kinase 2 (CK2). The classical antagonist of PAF receptor, WEB 2086, abrogated PAF-enhanced CK2 activity. CK2 activation by PAF was also inhibited when parasite extracts were assayed in the presence of modulators of PKC, MAPK, and both Ser/Thr and Tyr phosphatases. Finally, a cell permeable inhibitor of CK2 (DRB) suppressed PAF-induced cell differentiation in a dose-dependent manner.
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Affiliation(s)
- Mário A C Silva-Neto
- Departamento de Bioquímica Médica, ICB, CCS, Universidade Federal do Rio de Janeiro, UFRJ, P.O. Box 68041, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, CEP 21941-590, RJ, Brazil.
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