Navegando por Palavras-chave "Amastigote"
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- ItemSomente MetadadadosCharacterization of a 21 kDa protein from Trypanosoma cruzi associated with mammalian cell invasion(Elsevier B.V., 2009-04-01) Silva, Claudio V. da [UNIFESP]; Kawashita, Silvia Y. [UNIFESP]; Probst, Christian M.; Dallagiovanna, Bruno; Cruz, Mario C. [UNIFESP]; Silva, Erika A. da [UNIFESP]; Souto-Padron, Thais C. B. S.; Krieger, Marco A.; Goldenberg, Samuel; Briones, Marcelo R. S. [UNIFESP]; Andrews, Norma W.; Mortara, Renato A. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Fiocruz MS; Universidade Federal do Rio de Janeiro (UFRJ); Yale UnivTrypanosoma cruzi genomic database was screened for hypothetical proteins that showed high probability of being secreted or membrane anchored and thus, likely involved in host-cell invasion. A sequence that codes for a 21 kDa protein that showed high probability of being secreted was selected. After cloning this protein sequence, the results showed that it was a ubiquitous protein and secreted by extracellular amastigotes. the recombinant form (P21-His(6)) adhered to HeLa cells in a dose-dependent manner. Pretreatment of host cells with P21-His(6) inhibited cell invasion by extracellular amastigotes from G and CL strains. On the other hand, when the protein was added to host cells at the same time as amastigotes, an increase in cell invasion was observed. Host-cell pretreatment with P21-His(6) augmented invasion by metacyclic trypomastigotes. Moreover, polyclonal antibody anti-P21 inhibited invasion only by extracellular amastigotes and metacyclic trypomastigotes from G strain. These results suggested that P21 might be involved in T. cruzi cell invasion. We hypothesize that P21 could be secreted in the juxtaposition parasite-host cell and triggers signaling events yet unknown that lead to parasite internalization. (C) 2009 Elsevier Masson SAS. All rights reserved.
- ItemAcesso aberto (Open Access)Distinct genomic organization, mRNA expression and cellular localization of members of two amastin sub-families present in Trypanosoma cruzi(Biomed Central Ltd, 2013-01-17) Kangussu-Marcolino, Monica Mendes; Paiva, Rita Marcia Cardoso de; Araujo, Patricia Rosa; Mendonca-Neto, Rondon Pessoa de; Lemos, Laiane; Bartholomeu, Daniella Castanheira; Mortara, Renato Arruda [UNIFESP]; Da Rocha, Wanderson Duarte; Teixeira, Santuza Maria Ribeiro; Univ Fed Parana; Dept Bioquim & Imunol; Universidade Federal de Minas Gerais (UFMG); Universidade Federal de São Paulo (UNIFESP)Background: Amastins are surface glycoproteins (approximately 180 residues long) initially described in Trypanosoma cruzi as particularly abundant during the amastigote stage of this protozoan parasite. Subsequently, they have been found to be encoded by large gene families also present in the genomes of several species of Leishmania and in other Trypanosomatids. Although most amastin genes are organized in clusters associated with tuzin genes and are up-regulated in the intracellular stage of T. cruzi and Leishmania spp, distinct genomic organizations and mRNA expression patterns have also been reported.Results: Based on the analysis of the complete genome sequences of two T. cruzi strains, we identified a total of 14 copies of amastin genes in T. cruzi and showed that they belong to two of the four previously described amastin subfamilies. Whereas delta-amastin genes are organized in two or more clusters with alternating copies of tuzin genes, the two copies of beta-amastins are linked together in a distinct chromosome. Most T. cruzi amastins have similar surface localization as determined by confocal microscopy and western blot analyses. Transcript levels for delta-amastins were found to be up-regulated in amastigotes from several T. cruzi strains, except in the G strain, which is known to have low infection capacity. in contrast, in all strains analysed, beta-amastin transcripts are more abundant in epimastigotes, the stage found in the insect vector.Conclusions: Here we showed that not only the number and diversity of T. cruzi amastin genes is larger than what has been predicted, but also their mode of expression during the parasite life cycle is more complex. Although most T. cruzi amastins have a similar surface localization, only delta-amastin genes have their expression up-regulated in amastigotes. the results showing that a sub-group of this family is up-regulated in epimastigotes, suggest that, in addition of their role in intracellular amastigotes, T. cruzi amastins may also serve important functions during the insect stage of the parasite life cycle. Most importantly, evidence for their role as virulence factors was also unveiled from the data showing that delta-amastin expression is down regulated in a strain presenting low infection capacity.
- ItemAcesso aberto (Open Access)Role of Leishmania (Leishmania) amazonensis amastigote glycosphingolipids in macrophage infectivity(Associação Brasileira de Divulgação Científica, 2007-06-01) Tanaka, Améria Kaori [UNIFESP]; Gorin, Philip Albert James; Takahashi, Helio Kiyoshi [UNIFESP]; Straus, Anita Hilda [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade Federal do Paraná Departamento de BioquímicaThe role of glycosphingolipids (GSLs) present in amastigote forms of Leishmania (Leishmania) amazonensis during infection of macrophages was analyzed, with particular emphasis on GSLs presenting the terminal Galpß1-3Galpa disaccharide. Macrophage invasion by L. (L.) amazonensis amastigotes was reduced by 37% when the disaccharide Galpß1-3Galp (1 mM) was added to the culture medium. The putative macrophage receptor/lectin for ß-Gal-globotriaosylceramide (Galpß1-3Galpa1-4Galpß1-4Glc pß1-1Cer) and other structurally related GSLs from L. (L.) amazonensis amastigotes were analyzed by micelles and parasite binding assay to peritoneal macrophage proteins fractionated by SDS-PAGE under nonreducing conditions. Micelles containing purified amastigote GSLs or a suspention of L. (L.) amazonensis amastigotes fixed with 2% formaldehyde were incubated with nitrocellulose membrane containing the macrophage proteins transferred by Western blotting. Binding of micelles containing purified GSLs from amastigote forms or fixed L. (L.) amazonensis amastigotes to nitrocellulose membrane was probed using monoclonal antibody ST-3, which recognizes the glycoepitope Galpß1-3Galpa1-R present either in the micelle preparation or on the amastigote surface. Macrophage protein with molecular mass ~30 kDa bound the amastigote GSL and appeared to be a doublet on electrophoresis. The specificity of this interaction was confirmed using fixed L. (L.) chagasi amastigotes, which do not express GSLs such as ß-Galp-globotriaosylceramides, and which do not bind to 30-kDa protein.