Navegando por Palavras-chave "Host cell invasion"
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- ItemSomente MetadadadosARF6, PI3-kinase and host cell actin cytoskeleton in Toxoplasma gondii cell invasion(Elsevier B.V., 2009-01-16) Silva, Claudio Vieira da [UNIFESP]; Silva, Erika Alves da [UNIFESP]; Cruz, Mario Costa [UNIFESP]; Chavrier, Philippe; Mortara, Renato Arruda [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Inst Curie; Universidade Federal de Uberlândia (UFU)Toxoplasma gondii infects a variety of different cell types in a range of different hosts. Host cell invasion by T. gondii occurs by active penetration of the host cell, a process previously described as independent of host actin polymerization. Also, the parasitophorous vacuole has been shown to resist fusion with endocytic and exocytic pathways of the host cell. ADP-ribosylation factor-6 (ARF6) belongs to the ARE family of small GTP-binding proteins. ARF6 regulates membrane trafficking and actin cytoskeleton rearrangements at the plasma membrane. Here, we have observed that ARF6 is recruited to the parasitophorous vacuole of tachyzoites of T. gondii RH strain and it also plays an important role in the parasite cell invasion with activation of PI3-kinase and recruitment of PIP(2) and PIP(3) to the parasitophorous vacuole of invading parasites. Moreover, it was verified that maintenance of host cell actin cytoskeleton integrity is important to parasite invasion. (C) 2008 Elsevier Inc. All rights reserved.
- ItemSomente MetadadadosBeta-adrenergic antagonist propranolol inhibits mammalian cell lysosome spreading and invasion by Trypanosoma cruzi metacyclic forms(Elsevier Science Bv, 2017) Macedo, Silene [UNIFESP]; Ferreira Rodrigues, Joao Paulo [UNIFESP]; Schenkman, Sergio [UNIFESP]; Yoshida, Nobuko [UNIFESP]The involvement of beta-adrenergic receptor (beta-AR) in host cell invasion by Trypanosoma cruzi metacyclic trypomastigote (MT) is not known. We examined whether isoproterenol, an agonist of beta-AR, or nonselective beta-blocker propranolol affected MT internalization mediated the stage-specific surface molecule gp82. Treatment of HeLa cells with propranolol significantly inhibited MT invasion whereas isoproterenol had no effect. Propranolol, but not isoproterenol, also inhibited the lysosome spreading required for gp82-dependent MT invasion. The effect of propranolol in inhibiting MT internalization was not due to the prevention of gp82 interaction with beta-AR. It was mainly associated with its ability to impair lysosome spreading. (C) 2017 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
- ItemAcesso aberto (Open Access)ERM Proteins Play Distinct Roles in Cell Invasion by Extracellular Amastigotes of Trypanosoma cruzi(Frontiers Media Sa, 2017) Ferreira, Eden R. [UNIFESP]; Bonfim-Melo, Alexis [UNIFESP]; Cordero, Esteban M.; Mortara, Renato A. [UNIFESP]The protozoan parasite Trypanosoma cruzi is the causative agent of Chagas' disease. In mammalian hosts, T. cruzi alternates between trypomastigote and amastigote forms. Additionally, trypomastigotes can differentiate into amastigotes in the extracellular environment generating infective extracellular amastigotes (EAs). Ezrin-radixin-moesin (ERM) are key proteins linking plasma membrane to actin filaments, the major host cell component responsible for EA internalization. Our results revealed that depletion of host ezrin and radixin but not moesin inhibited EAs invasion in HeLa cells. ERM are recruited and colocalize with F-actin at EA invasion sites as shown by confocal microscopy. Invasion assays performed with cells overexpressing ERM showed increased EAs invasion in ezrin and radixin but not moesin overexpressing cells. Finally, time-lapse experiments have shown altered actin dynamics leading to delayed EA internalization in ezrin and radixin depleted cells when compared to control or moesin depleted cells. Altogether, these findings show distinct roles of ERM during EAs invasion, possibly regulating F-actin dynamics and plasma membrane interplay.
- ItemAcesso aberto (Open Access)Host cell invasion and oral infection by Trypanosoma cruzi strains of genetic groups TcI and TcIV from chagasic patients(Biomed Central Ltd, 2016) Maeda, Fernando Yukio [UNIFESP]; Clemente, Tatiana Mordente [UNIFESP]; Macedo, Silene [UNIFESP]; Cortez, Cristian [UNIFESP]; Yoshida, Nobuko [UNIFESP]Background: Outbreaks of acute Chagas disease by oral infection have been reported frequently over the last ten years, with higher incidence in northern South America, where Trypanosoma cruzi lineage TcI predominates, being responsible for the major cause of resurgent human disease, and a small percentage is identified as TcIV. Mechanisms of oral infection and host-cell invasion by these parasites are poorly understood. To address that question, we analyzed T. cruzi strains isolated from chagasic patients in Venezuela, Guatemala and Brazil. Methods: Trypanosoma cruzi metacyclic trypomastigotes were orally inoculated into mice. The mouse stomach collected four days later, as well as the stomach and the heart collected 30 days post-infection, were processed for histological analysis. Assays to mimic parasite migration through the gastric mucus layer were performed by counting the parasites that traversed gastric mucin-coated transwell filters. For cell invasion assays, human epithelial HeLa cells were incubated with metacyclic forms and the number of internalized parasites was counted. Results: All TcI and TcIV T. cruzi strains were poorly infective by the oral route. Parasites were either undetectable or were detected in small numbers in the mouse stomach four days post oral administration. Replicating parasites were found in the stomach and/or in the heart 30 days post-infection. As compared to TcI lineage, the migration capacity of TcIV parasites through the gastric mucin-coated filter was higher but lower than that exhibited by TcVI metacyclic forms previously shown to be highly infective by the oral route. Expression of pepsin-resistant gp90, the surface molecule that downregulates cell invasion, was higher in TcI than in TcIV parasites and, accordingly, the invasion capacity of TcIV metacyclic forms was higher. Gp90 molecules spontaneously released by TcI metacyclic forms inhibited the parasite entry into host cells. TcI parasites exhibited low intracellular replication rate. Conclusions: Our findings indicate that the poor capacity of TcI lineage, and to a lesser degree of TcIV parasites, in invading gastric epithelium after oral infection of mice may be associated with the inefficiency of metacyclic forms, in particular of TcI parasites, to migrate through the gastric mucus layer, to invade target epithelial cells and to replicate intracellularly.
- ItemAcesso aberto (Open Access)As vias de Cdc42/N-WASP e Rac1/WAVE2 na dinâmica de actina durante a invasão celular pelos amastigotas extracelulares de Trypanosoma cruzi(Universidade Federal de São Paulo (UNIFESP), 2016-11-30) Melo, Alexis de Sá Ribeiro do Bonfim de [UNIFESP]; Mortara, Renato Arruda [UNIFESP]; http://lattes.cnpq.br/3754467086294573; http://lattes.cnpq.br/4256258817790019; Universidade Federal de São Paulo (UNIFESP)Host cell invasion by extracellular amastigotes (EA) of Trypanosoma cruzi is highly dependent on actin cytoskeleton of host cells whose regulatory cellular mechanisms are still poorly understood. Cdc42 and Rac1 GTPases are key mediators of the actin cytoskeleton promoting Arp2/3 complex-dependent actin polymerization via activation of their effector proteins, N-WASP and WAVE2, respectively. The aim of this study was to evaluate the participation Cdc42/N-WASP and Rac1/WAVE2 signaling pathways in actin dynamics during EA internazalization in HeLa cells. Using live-cell imaging in confocal microscope it was observed that Cdc42 and Rac1 are recruited to and colocalize with actin during whole period of EA internalisation. GTPases recruitment was sustained in groups expressing active (CA) or inactive (DN) mutant isoforms when compared to native isoforms (WT). When the invasion ability was compared to control groups, the expression of Rac1 CA and Cdc42 WT increased the number of internalized parasites while Rac1 DN and Cdc42 CA expression reduced it. Additionally, the invasion of EAs is inhibited in cells depleted for Rac1 and also recruitment assays using live cells showed delayed invasion despite no effective reduction in amount of polymerized actin at EA invasion sites. For cells depleted for Cdc42 it was observed inhibition of EA internalization in some experiments, but no inhibition in others; live-cell imaging assays also revealed no delay in actin recruitment in this group. In cells depleted for N-WASP and WAVE2 proteins it was also observed inhibition and delay in the internalization without reduction in actin polymerization. Both proteins were also recruited to and colocalized with actin in EA invasion sites. Finally, depletion of four proteins studied did not affect the density or morphology of membrane projections mobilized by AEs as observed by scanning electron microscopy. The overall result confirms the participation of Cdc42/N-WASP and Rac1/WAVE2 signaling pathways in actin dynamics during EA host cell invasion and encourage the study of other proteins possibly cooperating in these pathways.