Navegando por Palavras-chave "metacyclic trypomastigotes"
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- ItemSomente MetadadadosActivation of distinct signal transduction pathways in Trypanosoma cruzi isolates with differential capacity to invade host cells(Elsevier B.V., 2002-04-01) Neira, I; Ferreira, A. T.; Yoshida, N.; Universidade Federal de São Paulo (UNIFESP)Mammalian cell invasion by Trypanosoma cruzi requires the activation of signal transduction pathways that result in a Ca2+ response both in the parasite and the host cell. By using drugs that interfere with the signalling processes, we investigated if the difference in the ability of T. cruzi isolates to invade host cells was associated with the activation of distinct signalling routes in the parasites. Experiments were performed with metacyclic trypomastigotes, the developmental forms that initiate infection in the mammalian host, using the highly invasive isolate CL and the poorly infective isolate G, which belong to distinct phylogenetic lineages. Treatment of parasites with adenylyl cyclase activator forskolin increased the infectivity of the G but not of the CL isolate towards HeLa cells. On the other hand, a specific protein tyrosine kinase inhibitor genistein reduced by similar to75% the penetration of CL but not of G isolate into HeLa cells. in the CL but not in the G isolate, protein tyrosine kinase mediated the phosphorylation of a 175 kDa protein in a manner inducible by a HeLa cell extract. Upon treatment with the phospholipase C inhibitor U73122, or with drugs such as caffeine, which affects Ca2+ release from inositol-1,4,5-triphosphate-sensitive stores, or thapsigargin, an inhibitor of intracellular Ca2+ transport ATPases, the infectivity of the CL but not of the G isolate diminished significantly (P < 0.005). in both isolates, a combination of ionomycin plus NH4Cl or nigericin released Ca2+ from acidic vacuoles containing a Ca2+/H+, exchange system. This treatment reduced the infectivity of metacyclic forms of the G but not of the CL isolate. Taken together, these data suggest that, fur host cell invasion, distinct signalling pathways are activated in metacyclic trypomastigotes of the two isolates, leading to Ca2+ release from different intracellular compartments. (C) 2002 Australian Society for Parasitology Inc. Published by Elsevier B.V. All rights reserved.
- ItemSomente MetadadadosInteraction with host factors exacerbates Trypanosoma cruzi cell invasion capacity upon oral infection(Elsevier B.V., 2007-12-01) Covarrubias, Charles; Cortez, Mauro; Ferreira, Daniele; Yoshida, Nobuko; Universidade Federal de São Paulo (UNIFESP)Outbreaks of severe acute Chagas' disease acquired by oral infection, leading to death in some cases, have occurred in recent years. Using the mouse model, we investigated the basis of such virulence by analyzing a Trypanosoma cruzi isolate, SC, from a patient with severe acute clinical symptoms, who was infected by oral route. It has previously been shown that, upon oral inoculation into mice, T. cruzi metacyclic trypomastigotes invade the gastric mucosal epithelium by engaging the stage-specific surface glycoprotein gp82, whereas the surface molecule gp90 functions as a down-modulator of cell invasion. We found that, when orally inoculated into mice, metacyclic forms of the SC isolate, which express high levels of gp90, produced high parasitemias and high mortality, in sharp contrast with the reduced infectivity in vitro. Upon recovery from the mouse stomach I h after oral inoculation, the gp90 molecule of the parasites was completely degraded, and their entry into HeLa cells, as well as into Caco-2 cells, was increased. the gp82 molecule was more resistant to digestive action of the gastric juice. Host cell invasion of SC isolate metacyclic trypomastigotes was augmented in the presence of gastric mucin. No alteration in infectivity was observed in T. cruzi strains CL and G which were used as references and which express gp90 molecules resistant to degradation by gastric juice. Taken together, our findings suggest that the exacerbation of T. cruzi infectivity, such as observed upon interaction of the SC isolate with the mouse stomach components, may be responsible for the severity of acute Chagas' disease that has been reported in outbreaks of oral T. cruzi infection. (C) 2007 Australian Society for Parasitology Inc. Published by Elsevier B.V. All rights reserved.
- ItemSomente MetadadadosMolecular basis of non-virulence of Trypanosoma cruzi clone CL-14(Elsevier B.V., 2004-06-01) Atayde, V. D.; Neira, I; Cortez, M.; Ferreira, D.; Freymuller, E.; Yoshida, N.; Universidade Federal de São Paulo (UNIFESP)We investigated the properties of metacyclic trypomastigotes of non-virulent Trypanosoma cruzi. clone CL-14, as compared to the parental isolate CL. in contrast to the CL isolate, which produces high parasitemias in mice, metacyclic forms of clone CL-14 failed to produce patent infection. in vitro, the number of clone CL-14 parasites that entered epithelial HeLa cells, after 1 h incubation, was approximately four-fold lower than that of the CL isolate and at 72 h post-infection intracellular replication was not apparent whereas cells infected with the CL isolate contained large number of parasites replicating as amastigotes. CL isolate metacyclic forms were long and slender, with the kinetoplast localised closer to the nucleus than to the posterior end, whereas clone CL-14 parasites were shorter, with the kinetoplast very close to the posterior end. Cysteine proteinase cruzipain and trans-sialidase activities were lower in CL isolate than in clone CL-14. the surface profile was similar, except that the expression of gp82, the stage-specific glycoprotein that promotes CL isolate mucosal infection in vivo and host cell invasion in vitro, was greatly reduced on the surface of clone CL-14 metacyclic forms. Genistein, a specific inhibitor of protein tyrosine kinase, which is activated in CL isolate by binding of gp82 to its host cell receptor, did not affect host cell entry of clone CL-14. in contrast with CL isolate, the infectivity of clone CL-14 was not affected by phospholipase C inhibitor U7312.2 but was diminished by a combination of ionomycin plus NH4Cl, which releases Ca2+ from acidic vacuoles. Internalisation of clone CL-14, but not of CL isolate, was significantly increased by treating parasites with neuraminidase, which removes sialic acid from the mucin-like surface molecule gp35/50. Taken together, our data suggest an association between the non-virulence of clone CL-14 metacyclic forms and the reduced expression of gp82, which precludes the activation of signal transduction pathways leading to effective host cell invasion. (C) 2004 Australian Society for Parasitology Inc. Published by Elsevier B.V. All rights reserved.
- ItemAcesso aberto (Open Access)Molecular mechanisms of Trypanosoma cruzi infection by oral route(Instituto Oswaldo Cruz, Ministério da Saúde, 2009-07-01) Yoshida, Nobuko [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Frequent reports on outbreaks of acute Chagas' disease by ingestion of food contaminated with parasites from triatomine insects illustrate the importance of this mode of transmission. Studies on oral Trypanosoma cruzi infection in mice have indicated that metacyclic trypomastigotes invade the gastric mucosal epithelium. A key molecule in this process is gp82, a stage-specific surface glycoprotein that binds to both gastric mucin and to target epithelial cells. By triggering Ca2+ signalling, gp82 promotes parasite internalisation. Gp82 is relatively resistant to peptic digestion at acidic pH, thus preserving the properties critical for oral infection. The infection process is also influenced by gp90, a metacyclic stage-specific molecule that negatively regulates the invasion process. T. cruzi strains expressing high gp90 levels invade cells poorly in vitro. However, their infectivity by oral route varies considerably due to varying susceptibilities of different gp90 isoforms to peptic digestion. Parasites expressing pepsin-susceptible gp90 become highly invasive against target cells upon contact with gastric juice. Such is the case of a T. cruzi isolate from an acute case of orally acquired Chagas' disease; the gp90 from this strain is extensively degraded upon short period of parasite permanence in the gastric milieu. If such an exacerbation of infectivity occurs in humans, it may be responsible for the severity of Chagas' disease reported in outbreaks of oral infection.
- ItemAcesso aberto (Open Access)Organization and expression of a multigene family encoding the surface glycoproteins of Trypanosoma cruzi metacyclic trypomastigotes involved in the cell invasion(Instituto Oswaldo Cruz, Ministério da Saúde, 1999-09-01) Carmo, Mirian S [UNIFESP]; Araya, Jorge E; Ramirez, Marcel I [UNIFESP]; Boscardin, Silvia Beatriz [UNIFESP]; Cano, Maria I [UNIFESP]; Baida, Renata Cristina Pardos [UNIFESP]; Ruiz, Rita C [UNIFESP]; Santos, Marcia Regina Machado [UNIFESP]; Chiurillo, Miguel A; Ramirez, José L; Yoshida, Nobuko [UNIFESP]; Franco da Silveira, José [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidad de Antofagasta; Universidad Central de Venezuela
- ItemAcesso aberto (Open Access)Signal transduction induced in Trypanosoma cruzi metacyclic trypomastigotes during the invasion of mammalian cells(Associação Brasileira de Divulgação Científica, 2000-03-01) Yoshida, Nobuko [UNIFESP]; Favoreto Junior, Silvio [UNIFESP]; Ferreira, Alice Teixeira [UNIFESP]; Manque, Patricio Andres Manque [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Penetration of Trypanosoma cruzi into mammalian cells depends on the activation of the parasite's protein tyrosine kinase and on the increase in cytosolic Ca2+ concentration. We used metacyclic trypomastigotes, the T. cruzi developmental forms that initiate infection in mammalian hosts, to investigate the association of these two events and to identify the various components of the parasite signal transduction pathway involved in host cell invasion. We have found that i) both the protein tyrosine kinase activation, as measured by phosphorylation of a 175-kDa protein (p175), and Ca2+ mobilization were induced in the metacyclic forms by the HeLa cell extract but not by the extract of T. cruzi-resistant K562 cells; ii) treatment of parasites with the tyrosine kinase inhibitor genistein blocked both p175 phosphorylation and the increase in cytosolic Ca2+ concentration; iii) the recombinant protein J18, which contains the full-length sequence of gp82, a metacyclic stage surface glycoprotein involved in target cell invasion, interfered with tyrosine kinase and Ca2+ responses, whereas the monoclonal antibody 3F6 directed at gp82 induced parasite p175 phosphorylation and Ca2+ mobilization; iv) treatment of metacyclic forms with phospholipase C inhibitor U73122 blocked Ca2+ signaling and impaired the ability of the parasites to enter HeLa cells, and v) drugs such as heparin, a competitive IP3-receptor blocker, caffeine, which affects Ca2+ release from IP3-sensitive stores, in addition to thapsigargin, which depletes intracellular Ca2+ compartments and lithium ion, reduced the parasite infectivity. Taken together, these data suggest that protein tyrosine kinase, phospholipase C and IP3 are involved in the signaling cascade that is initiated on the parasite cell surface by gp82 and leads to Ca2+ mobilization required for target cell invasion.
- ItemSomente MetadadadosTrypanosoma cruzi 175-kDa protein tyrosine phosphorylation is associated with host cell invasion(Academic Press Inc, 1998-06-01) Favoreto, S.; Dorta, M. L.; Yoshida, N.; Universidade Federal de São Paulo (UNIFESP)We examined the requirement of Trypanosoma cruzi protein tyrosine phosphorylation for parasite entry into mammalian cells and analyzed the profile of phosphorylated proteins in infective trypomastigotes. Treatment of metacyclic or tissue culture trypomastigotes with genistein, an inhibitor of protein tyrosine kinase activity, significantly inhibited invasion of cultured HeLa cells. A soluble factor, contained in HeLa cell extract and absent in the extract or T. cruzi-resistant K562 cells, greatly enhanced phosphorylation levels of a 175-kDa protein (p175) in trypomastigotes. Genistein inhibited p175 tyrosine phosphorylation. P175 was undetectable in noninvasive epimastigotes. the phosphorylation-inducing activity of HeLa cell extract was abrogated by adsorption with metacyclic trypomastigotes but not with epimastigotes or when it was mixed with recombinant protein Jig, which contains the entire peptide sequence of gp82, a metacyclic stage-specific surface glycoprotein implicated in target cell invasion. These data suggest ttl;it. in metacyclic trypomastigotes, gp82 is the signaling receptor that mediates protein tyrosine phosphorylation necessary for host cell invasion. (C) 1998 Academic Press.
- ItemSomente MetadadadosTrypanosoma cruzi infection by oral route How the interplay between parasite and host components modulates infectivity(Elsevier B.V., 2008-06-01) Yoshida, Nobuko [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Trypanosoma cruzi infection by oral route constitutes the most important mode of transmission in some geographical regions, as illustrated by reports on microepidemics and outbreaks of acute Chagas' disease acquired by ingestion of food contaminated with parasites from triatomine insects. in the mouse model, T cruzi metacyclic trypomastigotes invade the gastric mucosal epithelium, a unique portal of entry for systemic infection. High efficiency of metacyclic forms in establishing infection by oral route is associated with expression of gp82, a stage-specific surface molecule that binds to gastric mucin and to epithelial cells. Gp82 promotes parasite entry by triggering the signaling cascades leading to intracellular Ca2+ mobilization. T cruzi strains deficient in gp82 can effectively invade cells in vitro, by engaging the Ca2+ signal-inducing surface glycoprotein gp30. However, they are poorly infective in mice by oral route because gp30 has low affinity for gastric mucin. Metacyclic forms also express gp90, a stage-specific surface glycoprotein that binds to host cells and acts as a negative regulator of invasion. T cruzi strains expressing gp90 at high levels, in addition to gp82 and gp30, are all poor cell invaders in vitro. Notwithstanding, their infectivity by oral route may vary because, unlike gp82 and gp30, which resist degradation by pepsin in the gastric milieu, the gp90 isoforms of different strains have varying susceptibility to peptic digestion. for instance, in a T cruzi isolate, derived from an acute case of Chagas' disease acquired by oral route, gp90 is extensively degraded by gastric juice in the mouse stomach and this renders the parasite highly invasive towards target cells. If such an exacerbation of infectivity occurs in humans, it may be responsible for the severity of the disease reported in outbreaks of oral infection. (c) 2007 Elsevier Ireland Ltd. All rights reserved.