Navegando por Palavras-chave "Extracellular amastigotes"

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    Lysosomal integral membrane protein 2 (LIMP-2) restricts the invasion of Trypanosoma cruzi extracellular amastigotes through the activity of the lysosomal enzyme beta-glucocerebrosidase
    (Elsevier B.V., 2014-03-01) Goncalves, Viviane Martinelli [UNIFESP]; D'Almeida, Vania [UNIFESP]; Mueller, Karen Barbosa [UNIFESP]; Real, Fernando [UNIFESP]; Mortara, Renato Arruda [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Lysosomal integral membrane protein 2 (LDM1P-2, SCARB2) is directly linked to beta-glucocerebrosidase enzyme (beta GC) and mediates the transport of this enzyme from the Golgi complex to lysosomes. Active beta GC cleaves the beta-glycosidic linkages of glucosylceramide, an intermediate in the metabolism of sphingoglycolipids, generating ceramide. in this study we used mouse embryonic fibroblasts (MEFs) deficient for LIMP-2 and observed that these cells were more susceptible to infection by extracellular amastigotes of the protozoan parasite Trypanosoma cruzi when compared to wild-type (WT) fibroblasts. the absence of LIMP-2 decreases the activity of beta GC measured in fibroblast extracts. Replacement of beta GC enzyme in LIMP-2 deficient fibroblasts restores the infectivity indices to those of WT cells in T cruzti invasion assays. Considering the participation of beta GC in the production of host cell ceramide, we propose that T cruzi extracellular amastigotes are more invasive to cells deficient in this membrane component. These results contribute to our understanding of the role of host cell lysosomal components in T cruzi invasion. (C) 2013 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
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    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.