title: Fibronectin-degrading activity of Trypanosoma cruzi cysteine proteinase plays a role in host cell invasion.
abstract: Trypanosoma cruzi, the agent of Chagas disease, binds to diverse extracellular matrix proteins. Such an ability prevails in the parasite forms that circulate in the bloodstream and contributes to host cell invasion. Whether this also applies to the insect-stage metacyclic trypomastigotes, the developmental forms that initiate infection in the mammalian host, is not clear. Using T. cruzi CL strain metacyclic forms, we investigated whether fibronectin bound to the parasites and affected target cell invasion. Fibronectin present in cell culture medium bound to metacyclic forms and was digested by cruzipain, the major T. cruzi cysteine proteinase. G strain, with negligible cruzipain activity, displayed a minimal fibronectin-degrading effect. Binding to fibronectin was mediated by gp82, the metacyclic stage-specific surface molecule implicated in parasite internalization. When exogenous fibronectin was present at concentrations higher than cruzipain can properly digest, or fibronectin expression was stimulated by treatment of epithelial HeLa cells with transforming growth factor beta, the parasite invasion was reduced. Treatment of HeLa cells with purified recombinant cruzipain increased parasite internalization, whereas the treatment of parasites with cysteine proteinase inhibitor had the opposite effect. Metacyclic trypomastigote entry into HeLa cells was not affected by anti-β1 integrin antibody but was inhibited by anti-fibronectin antibody. Overall, our results have indicated that the cysteine proteinase of T. cruzi metacyclic forms, through its fibronectin-degrading activity, is implicated in host cell invasion.
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Fernando Yukio
authors.initials: FY
authors.lastname: Maeda
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Cristian
authors.initials: C
authors.lastname: Cortez
authors.affiliation: Departamento de Biofísica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Mario Augusto
authors.initials: MA
authors.lastname: Izidoro
authors.affiliation: Departamento de Biofísica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Luiz
authors.initials: L
authors.lastname: Juliano
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil nyoshida@unifesp.br.
authors.forename: Nobuko
authors.initials: N
authors.lastname: Yoshida
mesh_terms: D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004705:Endocytosis; D005353:Fibronectins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D059748:Proteolysis; D015800:Protozoan Proteins; D014349:Trypanosoma cruzi / Q000201:enzymology* / Q000502:physiology*
chemical_list: D005353:Fibronectins; D015800:Protozoan Proteins; D003546:Cysteine Endopeptidases; C063214:cruzipain