Entamoeba histolytica: Involvement of pp125(FAK) in collagen-induced signal transduction

The interaction of Entamoeba histolytica trophozoites with collagen involves cell adherence, formation, and release of electron dense granules (EDGs) containing collagenase activity lending to the degradation of the bound protein. The binding is thought to be mediated by an ''integrin-like'' collagen receptor. Since the signal transduction mechanisms triggered by the collagen-trophozoite interaction are unknown, but clearly involve cytoskeletal organization, we decided to explore the role of protein tyrosine phosphorylation in this process. Collagen induces a time-dependent increase in the phosphorylation of several polypetides migrating around 67 and 110 kDa. One polypeptide of the high-molecular-weight component was identified as a 125-kDa protein with very similar epitopes to the focal adhesion kinase, pp125(FAK). Another protein that became tyrosine phosphorylated upon collagen treatment was a 42-kDa polypeptide related to the mitogen activated protein kinase (MAPK) family. Our results suggest that tyrosine phosphorylation is involved in collagen signaling in amoebas and that pp 125(FAK) and p42(MAPK) homologs may play on active role in turning on the genetic program that enables the parasite to invade its host. (C) 1996 Academic Press, Inc.