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Trypanosoma cruzi 175-kDa protein tyrosine phosphorylation is associated with host cell invasion
S Favoreto1, M L Dorta, N Yoshida
1Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, SP, Brazil.
Abstract:
We examined the requirement of Tropanosoma cruzi protein tyrosine phosphorylation for parasite entry into mammalian cells and analyzed the profile of phosphorylated proteins in infective trypomastigotes. Treatment of metacyclic or tissue culture trypomastigotes with genistein, an inhibitor of protein tyrosine kinase activity, significantly inhibited invasion of cultured HeLa cells. A soluble factor, contained in HeLa cell extract and absent in the extract ot T. cruzi-resistant K562 cells, greatly enhanced phosphorylation levels of a 175-kDa protein (p175) in trypomastigotes. Genistein inhibited p175 tyrosine phosphorylation. P175 was undetectable in noninvasive epimastigotes. The phosphorylation-inducing activity of HeLa cell extract was abrogated by adsorption with metacyclic trypomastigotes but not with epimastigotes or when it was mixed with recombinant protein J18, which contains the entire peptide sequence of gp82, a metacyclic stage-specific surface glycoprotein implicated in target cell invasion. These data suggest that, in metacyclic trypomastigotes, gp82 is the signaling receptor that mediates protein tyrosine phosphorylation necessary for host cell invasion.
Insights
Protein tyrosine phosphorylation in Trypanosoma cruzi is essential for invasion into host cells. The surface glycoprotein gp82 acts as a signaling receptor, mediating this phosphorylation for successful parasite entry.
Area of Science:
- Parasitology
- Molecular Biology
- Cell Biology
Background:
- Trypanosoma cruzi infection requires specific parasite-host interactions.
- Protein tyrosine phosphorylation plays a role in pathogen invasion.
- The surface glycoprotein gp82 is implicated in T. cruzi target cell invasion.
Purpose of the Study:
- To investigate the role of protein tyrosine phosphorylation in Trypanosoma cruzi invasion.
- To identify phosphorylated proteins involved in parasite entry.
- To elucidate the function of gp82 in host cell invasion.
Main Methods:
- Inhibition of protein tyrosine kinase activity using genistein.
- Analysis of protein phosphorylation profiles in trypomastigotes.
- Use of cell extracts to study phosphorylation-inducing factors.
- Adsorption assays with parasite stages and recombinant proteins.
Main Results:
- Genistein treatment significantly inhibited T. cruzi invasion of HeLa cells.
- A 175-kDa protein (p175) showed enhanced tyrosine phosphorylation in trypomastigotes upon exposure to HeLa cell extract.
- Genistein inhibited p175 tyrosine phosphorylation, and p175 was absent in noninvasive epimastigotes.
- HeLa cell extract's phosphorylation-inducing activity was blocked by metacyclic trypomastigotes but not epimastigotes or recombinant gp82.
Conclusions:
- Protein tyrosine phosphorylation is crucial for Trypanosoma cruzi invasion of mammalian cells.
- The metacyclic stage-specific surface glycoprotein gp82 functions as a signaling receptor.
- gp82 mediates protein tyrosine phosphorylation required for host cell invasion by T. cruzi.