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Infection and Immunity, March 2003, p. 1561-1565, Vol. 71, No. 3
0019-9567/03/$08.00+0     DOI: 10.1128/IAI.71.3.1561-1565.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

Cell Adhesion and Ca²⁺ Signaling Activity in Stably Transfected Trypanosoma cruzi Epimastigotes Expressing the Metacyclic Stage-Specific Surface Molecule gp82

Patricio M. Manque,^1, Ivan Neira,¹ Vanessa D. Atayde,¹ Esteban Cordero,¹ Alice T. Ferreira,² José Franco da Silveira,¹ Marcel Ramirez,^1, and Nobuko Yoshida^1*

Departamento de Microbiologia, Imunologia e Parasitologia,¹ Departamento de Biofísica, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, Brazil²

Received 12 August 2002/ Returned for modification 3 October 2002/ Accepted 13 December 2002

Metacyclic trypomastigotes of Trypanosoma cruzi express a developmentally regulated 82-kDa surface glycoprotein (gp82) that has been implicated in host cell invasion. gp82-mediated interaction of metacyclic forms with target cells induces in both cells activation of the signal transduction pathways, leading to intracellular Ca²⁺ mobilization, which is required for parasite internalization. Noninfective epimastigotes do not express detectable levels of gp82 and are unable to induce a Ca²⁺ response. We stably transfected epimastigotes with a T. cruzi expression vector carrying the metacyclic stage gp82 cDNA. These transfectants produced a functional gp82, which bound to and triggered a Ca²⁺ response in HeLa cells, in the same manner as the metacyclic trypomastigote gp82. Such properties were not found in epimastigotes transfected with the plasmid vector alone. Epimastigotes expressing gp82 on the surface adhered to HeLa cells but were not internalized. Treatment of gp82-expressing epimastigotes with forskolin, an activator of adenylyl cyclase that increases the metacyclic trypomastigote entry into target cells, did not promote parasite internalization. P175, an intracellular tyrosine phosphorylated protein, which appears to play a role in gp82-dependent signaling cascade in metacyclic forms, was undetectable in epimastigotes, either transfected or not with pTEX-gp82. Overall, our results indicate that gp82 is required but not sufficient for target cell invasion.

Editor: J. M. Mansfield

Present address: Department of Microbiology and Immunology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Va.

Present address: Departamento de Genética, Universidade Federal de Pernambuco, Recife, PE, Brazil.

This article has been cited by other articles:

• Cortez, M., Neira, I., Ferreira, D., Luquetti, A. O., Rassi, A., Atayde, V. D., Yoshida, N. (2003). Infection by Trypanosoma cruzi Metacyclic Forms Deficient in gp82 but Expressing a Related Surface Molecule, gp30. Infect. Immun. 71: 6184-6191 [Abstract] [Full Text]