Organization and expression of a multigene family encoding the surface glycoproteins of Trypanosoma cruzi metacyclic trypomastigotes involved in the cell invasion

ABSTRACT Trypanosoma cruzi metacyclic trypomastigotes invade and replicate in the gastric mucosal epithelium after oral infection. In this study we analyzed the process of infection by T. cruzi isolates deficient in the expression of gp82, the metacyclic stage-specific surface glycoprotein implicated in target cell entry in vitro and in promoting mucosal infection in mice after oral challenge. Mice infected by the oral route with metacyclic forms of gp82-deficient isolate 569 or 588 developed patent parasitemia but at greatly reduced levels compared to those infected with the gp82-expressing isolate CL. Metacyclic forms of both isolates expressed gp30, a surface glycoprotein detectable by monoclonal antibody (MAb) 3F6 directed to gp82. Otherwise, the gp82-deficient isolates displayed a surface profile similar to that of the CL isolate and also entered epithelial HeLa cells in a manner inhibitable by MAb 3F6 and dependent on the parasite signal transduction that involved the activation of protein tyrosine kinase and Ca2+ mobilization from thapsigargin-sensitive stores. Like gp82, gp30 triggered the host cell Ca2+ response required for parasite internalization. Purified gp30 and the recombinant gp82 inhibited HeLa cell invasion of metacyclic forms of isolates 569 and 588 by ∼90 and ∼70%, respectively. A cell invasion assay performed in the presence of gastric mucin, mimicking the in vivo infection, showed an inhibition of 70 to 75% in the internalization of gp82-deficient isolates but not of the CL isolate. The recombinant gp82 exhibited an adhesive capacity toward gastric mucin much higher than that of gp30. Taken together, our findings indicate that target cell entry of metacyclic trypomastigotes can be mediated either by gp82 or gp30 but that efficient mucosal infection depends on the expression of gp82.

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Molecular basis of mammalian cell invasion by Trypanosoma cruzi

Anais da Academia Brasileira de Ciências ◽

10.1590/s0001-37652006000100010 ◽

2006 ◽

Vol 78 (1) ◽

pp. 87-111 ◽

Cited By ~ 148

Author(s):

Nobuko Yoshida

Keyword(s):

Trypanosoma Cruzi ◽

Cell Invasion ◽

Target Cell ◽

Protein Tyrosine Kinase ◽

Host Cells ◽

Target Cells ◽

Cytokeratin 18 ◽

Parasite Protein ◽

Oligopeptidase B ◽

Surface Glycoproteins

Establishment of infection by Trypanosoma cruzi, the agent of Chagas' disease, depends on a series of events involving interactions of diverse parasite molecules with host components. Here we focus on the mechanisms of target cell invasion by metacyclic trypomastigotes (MT) and mammalian tissue culture trypomastigotes (TCT). During MT or TCT internalization, signal transduction pathways are activated both in the parasite and the target cell, leading to Ca2+ mobilization. For cell adhesion, MT engage surface glycoproteins, such as gp82 and gp35/50, which are Ca2+ signal-inducing molecules. In T. cruzi isolates that enter host cells in gp82-mediated manner, parasite protein tyrosine kinase as well as phospholipase C are activated, and Ca2+ is released from I P3-sensitive stores, whereas in T. cruzi isolates that attach to target cells mainly through gp35/50, the signaling pathway involving adenylate cyclase appears to be stimulated, with Ca2+ release from acidocalciosomes. In addition, T. cruzi isolate-dependent inhibitory signals, mediated by MT-specific gp90, may be triggered both in the host cell and the parasite. The repertoire of TCT molecules implicated in cell invasion includes surface glycoproteins of gp85 family, with members containing binding sites for laminin and cytokeratin 18, enzymes such as cruzipain, trans-sialidase, and an oligopeptidase B that generates a Ca2+-agonist from a precursor molecule.

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Infectivity of Trypanosoma cruzi strains is associated with differential expression of surface glycoproteins with differential Ca2+ signalling activity

Biochemical Journal ◽

10.1042/bj3300505 ◽

1998 ◽

Vol 330 (1) ◽

pp. 505-511 ◽

Cited By ~ 107

Author(s):

C. Rita RUIZ ◽

Silvio FAVORETO ◽

L. Miriam DORTA ◽

E. M. Maria OSHIRO ◽

T. Alice FERREIRA ◽

...

Keyword(s):

Trypanosoma Cruzi ◽

Hela Cells ◽

Strain Analysis ◽

Inverse Correlation ◽

Host Cells ◽

Target Cells ◽

Metacyclic Trypomastigotes ◽

Cell Components ◽

Major Surface ◽

Surface Glycoproteins

Mammalian cell invasion assays, using metacyclic trypomastigotes of Trypanosoma cruzi G and CL strains, showed that the CL strain enters target cells in several-fold higher numbers as compared with the G strain. Analysis of expression of surface glycoproteins in metacyclic forms of the two strains by iodination, immunoprecipitation and FACS, revealed that gp90, undetectable in the CL strain, is one of the major surface molecules in the G strain, that expression of gp82 is comparable in both strains and that gp35/50 is expressed at lower levels in the CL strain. Purified gp90 and gp35/50 bound more efficiently than gp82 to cultured HeLa cells. However, the intensity of the Ca2+ response triggered in HeLa cells by gp82 was significantly higher than that induced by gp35/50 or gp90. Most of the Ca2+ signalling activity of the metacyclic extract towards HeLa cells was due to gp82 and was inhibitable by gp82-specific monoclonal antibody 3F6. Ca2+ mobilization was also triggered in metacyclic trypomastigotes by host-cell components; it was mainly gp82-mediated and more intense in the CL than in the G strain. We propose that expression of gp90 and gp35/50 at high levels impairs binding of metacyclic forms to host cells through productive gp82-mediated interaction, which leads to the target-cell and parasite Ca2+ mobilization required for invasion. Analysis of metacyclic forms of eight additional T. cruzi strains corroborated the inverse correlation between infectivity and expression of gp90 and gp35/50.

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