Fibronectin-derived fragments as inducers of adhesion and chemotaxis of Entamoeba histolytica trophozoites.

Active migration of Entamoeba histolytica trophozoites through extracellular matrixes might play a role in host tissue destruction. Trophozoites degrade soluble fibronectin (FN) bound to their surface and adhere to substrate-bound FN, producing local degradation. FN proteolytic fragments were used to determine the nature of adhesion and motility-promoting domains within the protein. The 70-kDa fragment (amino-terminal end) promoted the highest adhesion, followed by the 120-kDa fragment, which contains the cell-binding domain. The 25-kDa fragment (carboxy-terminal end of the A chain) promoted half the adhesion, while two Hep II-binding fragments had no effect. The 70- and 120-kDa fragments also stimulated directed migration and chemokinesis. Intact FN and the 25-kDa fragment showed lower stimulation. The Hep II-binding fragments had no activity. Results support previous evidence for distinct cell-surface components as mediators of adhesion to FN and trophozoite motility and the potential importance of cell matrix recognition and degradation in their invasive behavior.