The Gp85 surface glycoproteins from Trypanosoma cruzi.

Trypanosoma cruzi strains show distinctive characteristics as genetic polymorphism and infectivity. Large repertoires of molecules, such as the Gp85 glycoproteins, members of the Gp85/Trans-sialidase superfamily, as well as multiple signaling pathways, are associated with invasion of mammalian cells by the parasite. Due to the large number of expressed members, encoded by more than 700 genes, the research focused on this superfamily conserved sequences is discussed. Binding sites to laminin have been identified at the N-terminus of the Gp85 molecules. Interestingly, the T. cruzi protein phosphorylation profile is changed upon parasite binding to laminin (or fibronectin), particularly the cytoskeletal proteins such as those from the paraflagellar rod and the tubulins, which are both markedly dephosphorylated. Detailed analysis of the signaling cascades triggered upon T. cruzi binding to extracellular matrix (ECM) proteins revealed the involvement of the MAPK/ERK pathway in this event. At the C-terminus, the conserved FLY sequence is a cytokeratin-binding domain and is involved in augmented host cell invasion in vitro and high levels of parasitemia in vivo. FLY, which is associated to tissue tropism and preferentially binds to the heart vasculature may somehow be correlated with the severe cardiac form, an important clinical manifestation of chronic Chagas' disease.