Platelet-activating factor induction of secreted phosphatase activity in Trypanosoma cruzi

Claudia D Rodrigues, P. M L Dutra, F. S. Barros, T. Souto-Padrón, J. R. Meyer-Fernandes, A. H C S Lopes

Research output: Contribution to journalArticle

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Abstract

The effects of platelet-activating factor (PAF) on the ecto-phosphatase activity of Trypanosoma cruzi were investigated. Living parasites hydrolyzed p-nitrophenylphosphate (p-NPP) at a rate of 5.71 ± 0.37 nmol P(i) mg-1 min-1. This ecto-phosphatase activity increased to 8.70 ± 1.12 nmol P(i) mg-1 min-1 when the cells were grown in the presence of 10-9 M PAF. This effect was probably due to stimulation of the release of the ecto-phosphatase and/or the secretion of an intracellular phosphatase to the extracellular medium, as suggested by cytochemical analysis. Modulation of the ecto-phosphatase activity was also observed when PAF was added during the time course of the reaction. WEB 2086, a competitive PAF antagonist, was able to revert PAF effects when both were used at the same concentration. When PAF was added to a membrane enriched fraction preparation of T. cruzi, no alteration on the phosphatase activity was observed. This result suggests an involvement of intracellular signaling, as PAF was only effective on intact cells. Sphingosine and phorbol-12-myristate-13-acetate (PMA) were then used to investigate a possible involvement of protein kinase C (PKC) with PAF-induced phosphatase secretion. Sphingosine by itself stimulated the secretion of a phosphatase but did not significantly interfere with PAF effects on this enzyme. On the other hand, PMA was able to abrogate PAF-induced release of this phosphatase. These data are highly suggestive of a putative involvement of signal transduction mediated by a ligand of mammalian origin (PAF), through PKC and a specific receptor located on the cell surface of the human parasite Trypanosoma cruzi.

Original languageEnglish
Pages (from-to)36-42
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume266
Issue number1
DOIs
StatePublished - Dec 9 1999
Externally publishedYes

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Trypanosoma cruzi
Platelet Activating Factor
Phosphoric Monoester Hydrolases
Sphingosine
WEB 2086
Protein Kinase C
Parasites
Acetates
Signal transduction
Signal Transduction
Modulation
Ligands
Membranes

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

Cite this

Platelet-activating factor induction of secreted phosphatase activity in Trypanosoma cruzi. / Rodrigues, Claudia D; Dutra, P. M L; Barros, F. S.; Souto-Padrón, T.; Meyer-Fernandes, J. R.; Lopes, A. H C S.

In: Biochemical and Biophysical Research Communications, Vol. 266, No. 1, 09.12.1999, p. 36-42.

Research output: Contribution to journalArticle

Rodrigues, Claudia D ; Dutra, P. M L ; Barros, F. S. ; Souto-Padrón, T. ; Meyer-Fernandes, J. R. ; Lopes, A. H C S. / Platelet-activating factor induction of secreted phosphatase activity in Trypanosoma cruzi. In: Biochemical and Biophysical Research Communications. 1999 ; Vol. 266, No. 1. pp. 36-42.
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AU - Meyer-Fernandes, J. R.

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AB - The effects of platelet-activating factor (PAF) on the ecto-phosphatase activity of Trypanosoma cruzi were investigated. Living parasites hydrolyzed p-nitrophenylphosphate (p-NPP) at a rate of 5.71 ± 0.37 nmol P(i) mg-1 min-1. This ecto-phosphatase activity increased to 8.70 ± 1.12 nmol P(i) mg-1 min-1 when the cells were grown in the presence of 10-9 M PAF. This effect was probably due to stimulation of the release of the ecto-phosphatase and/or the secretion of an intracellular phosphatase to the extracellular medium, as suggested by cytochemical analysis. Modulation of the ecto-phosphatase activity was also observed when PAF was added during the time course of the reaction. WEB 2086, a competitive PAF antagonist, was able to revert PAF effects when both were used at the same concentration. When PAF was added to a membrane enriched fraction preparation of T. cruzi, no alteration on the phosphatase activity was observed. This result suggests an involvement of intracellular signaling, as PAF was only effective on intact cells. Sphingosine and phorbol-12-myristate-13-acetate (PMA) were then used to investigate a possible involvement of protein kinase C (PKC) with PAF-induced phosphatase secretion. Sphingosine by itself stimulated the secretion of a phosphatase but did not significantly interfere with PAF effects on this enzyme. On the other hand, PMA was able to abrogate PAF-induced release of this phosphatase. These data are highly suggestive of a putative involvement of signal transduction mediated by a ligand of mammalian origin (PAF), through PKC and a specific receptor located on the cell surface of the human parasite Trypanosoma cruzi.

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