Navegando por Palavras-chave "trypomastigote"
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- ItemAcesso aberto (Open Access)Features of host cell invasion by different infective forms of Trypanosoma cruzi(Instituto Oswaldo Cruz, Ministério da Saúde, 1999-09-01) Mortara, Renato Arruda [UNIFESP]; Procópio, Daniela O [UNIFESP]; Barros, Helena C [UNIFESP]; Verbisck, Newton V [UNIFESP]; Andreoli, Walter K [UNIFESP]; Silva, Ricardo Bs [UNIFESP]; Silva, Solange da [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Through its life cycle from the insect vector to mammalian hosts Trypanosoma cruzi has developed clever strategies to reach the intracellular milieu where it grows sheltered from the hosts' immune system. We have been interested in several aspects of in vitro interactions of different infective forms of the parasite with cultured mammalian cells. We have observed that not only the classically infective trypomastigotes but also amastigotes, originated from the extracellular differentiation of trypomastigotes, can infect cultured cells. Interestingly, the process of invasion of different parasite infective forms is remarkably distinct and also highly dependent on the host cell type.
- ItemSomente MetadadadosMolecular, functional and structural properties of the prolyl oligopeptidase of Trypanosoma cruzi (POP Tc80), which is required for parasite entry into mammalian cells(Portland Press Ltd, 2005-05-15) Bastos, Izabela MD; Grellier, Philippe; Martins, Natalia F.; Cadavid-Restrepo, Gloria; Souza-Ault, Marian R. de; Augustyns, Koen; Teixeira, Antonio RL; Schrevel, Joseph; Maigret, Bernard; Silveira, José F. da [UNIFESP]; Santana, Jaime M.; Universidade de Brasília (UnB); Museum Natl Hist Nat; Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA); Univ Antwerp; Univ Nancy 1; Universidade Federal de São Paulo (UNIFESP)We have demonstrated that the 80 kDa POP Tc80 (prolyl oligopeptidase of Trypanosoma cruzi) is involved in the process of cell invasion, since specific inhibitors block parasite entry into non-phagocytic mammalian host cells. in contrast with other POPs, POP Tc80 is capable of hydrolysing large substrates, such as fibronectin and native collagen. in this study, we present the cloning of the POPTc80 gene, whose deduced amino acid sequence shares considerable identity with other members of the POP family, mainly within its C-terminal portion that forms the catalytic domain. Southern-blot analysis indicated that POPTc80 is present as a single copy in the genome of the parasite. These results are consistent with mapping of POPTc80 to a single chromosome. the active recombinant protein (rPOP Tc80) displayed kinetic properties comparable with those of the native enzyme. Novel inhibitors were assayed with rPOP Tc80, and the most efficient ones presented values of inhibition coefficient K(i) <= 1.52 nM. Infective parasites treated with these specific POP Tc80 inhibitors attached to the surface of mammalian host cells, but were incapable of infecting them. Structural modelling of POP Tc80, based on the crystallized porcine POP, suggested that POP Tc80 is composed of an alpha/beta-hydrolase domain containing the catalytic triad Ser(548)-Asp(631)-His(667). and a seven-bladed beta-propeller non-catalytic domain. Docking analysis suggests that triple-helical collagen access to the catalytic site of POP Tc80 occurs in the vicinity of the interface between the two domains.
- ItemSomente MetadadadosNovel strategy in Trypanosoma cruzi cell invasion: Implication of cholesterol and host cell microdomains(Elsevier B.V., 2007-11-01) Fernandes, Maria Cecilia; Cortez, Mauro; Geraldo Yoneyama, Kelly Aparecida; Straus, Anita Hilda; Yoshida, Nobuko; Mortara, Renato Arruda; Universidade Federal de São Paulo (UNIFESP)Trypanosoma cruzi, the etiological agent of Chagas' disease, is an obligatory intracellular parasite in the mammalian host. in order to invade a wide variety of mammalian cells, T cruzi engages parasite components that are differentially expressed among strains and infective forms. Because the identification of putative protein receptors has been particularly challenging, we investigated whether cholesterol and membrane rafts, sterol- and sphingolipid-enriched membrane domains, could be general host surface components involved in invasion of metacyclic trypomastigotes and extracellular amastigotes of two parasite strains with distinct infectivities. HeLa or Vero cells treated with methyl-beta-cyclodextrin (M beta CD) are less susceptible to invasion by both infective forms, and the effect was dose-dependent for trypomastigote but not amastigote invasion. Moreover, treatment of parasites with MPCD only inhibited trypomastigote invasion. Filipin labeling confirmed that host cell cholesterol concentrated at the invasion sites. Binding of a cholera toxin B subunit (CTX-B) to ganglioside GM1, a marker of membrane rafts, inhibited parasite infection. Cell labeling with CTX-B conjugated to fluorescein isothiocyanate revealed that not only cholesterol but also GM1 is implicated in parasite entry. These findings thus indicate that microdomains present in mammalian cell membranes, that are enriched in cholesterol and GM1, are involved in invasion by T cruzi infective forms. (c) 2007 Australian Society for Parasitology Inc. Published by Elsevier B.V. All rights reserved.
- ItemSomente MetadadadosPhosphatidylinositol-specific phospholipase C (PI-PLC) cleavage of GPI-anchored surface molecules of Trypanosoma cruzi triggers in vitro morphological reorganization of trypomastigotes(Soc Protozoologists, 2001-01-01) Mortara, R. A.; Minelli, LMS; Vandekerchove, F.; Nussenzweig, V; Ramalho-Pinto, F. J.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); NYU Med CtrTrypanosoma cruzi trypomastigotes treated with phosphatidylinositol-specific phospholipase C (PI-PLC) in vitro are rapidly induced to differentiate into round forms. Using confocal microscopy, we were able to show that trypomastigotes treated with PI-PLC initiate the process of flagellum remodeling by 30 sec after contact with the enzyme and amastigote-like forms are detected as early as 10 min after PI-PLC treatment. Scanning and transmission electron microscopy indicate that trypomastigotes undergo a previously undescribed process of flagellum circularization and internalization. Analysis of the flagellar complex with monoclonal antibody 4D9 shows heterogeneous labeling among the parasites, suggesting a remodeling of these molecules. After PI-PLC treatment, parasites rapidly lose the surface marker Ssp-3 and 24 h post-treatment they begin to exhibit a circular nucleus and a rod-shaped kinetoplast. By flow cytometry analysis and confocal microscopy, the Ssp-4 amastigote-specific epitope can be detected on the parasite surface. This indicates that thr release of trypomastigote GPI-anchored molecules by exogenous PI-PLC in vitro can trigger morphological changes.