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Type: Artigo de periódico
Title: Trypanosoma Cruzi Response To The Oxidative Stress Generated By Hydrogen Peroxide.
Author: Finzi, Jane K
Chiavegatto, Camila W M
Corat, Karen F
Lopez, Jorge A
Cabrera, Odalys G
Mielniczki-Pereira, Albanin A
Colli, Walter
Alves, Maria Júlia M
Gadelha, Fernanda R
Abstract: As an intracellular parasite, Trypanosoma cruzi is exposed to reactive oxygen species. The study of the proteins involved in the hydroperoxide detoxification cascade, tryparedoxin peroxidase included, may lead to the development of a more specific chemotherapy for Chagas'disease. In this work, the involvement of TcCPX in T. cruzi resistance to oxidant-mediated injury was investigated. At low concentrations of hydrogen peroxide cell proliferation was stimulated and parasites increased their resistance to sub-lethal doses of H2O2 (100 microM) if previously treated with a non-toxic concentration of H2O2 (20 microM). Incubation of cells with different H2O2 concentrations induced a dose-dependent increase in TcCPX levels, as detected by Western blotting analysis. The increase in TcCPX levels in the presence of high H2O2 concentrations possibly reflects an initial cell attempt to promote detoxification. To further demonstrate TcCPX involvement in T. cruzi response to oxidative stress, TcCPX overexpressing cells were produced. Compared to pTEX transformed cells, pTEX-TcCPX mutant cells showed a higher mRNA level (129%), without a corresponding increase in protein production (11%), suggesting that regulation of gene expression occurs at post-transcriptional levels. Furthermore, parasite treatment with 200 microM H2O2 for 30 min, led to an increase in mRNA (192%), but not in protein levels (24%). Higher mRNA levels correlated to protein levels were observed only after longer H2O2 incubation periods (1-2 h), suggesting that protein translation occurs accordingly to parasite needs. An increase in glucose-6-phosphate dehydrogenase activity was observed in pTEX-TcCPX epimastigotes that could provide cells with extra reducing power and a higher growth index.
Subject: Animals
Blotting, Northern
Blotting, Western
Gene Expression Regulation, Enzymologic
Glucosephosphate Dehydrogenase
Hydrogen Peroxide
Oxidative Stress
Protein Biosynthesis
Protozoan Proteins
Rna, Messenger
Reactive Oxygen Species
Transcription, Genetic
Trypanosoma Cruzi
Rights: fechado
Identifier DOI: 
Date Issue: 2004
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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