FIBRONECTIN-DERIVED FRAGMENTS AS INDUCERS OF ADHESION AND CHEMOTAXIS OF ENTAMOEBA-HISTOLYTICA TROPHOZOITES

Active migration of Entamoeba histolytica trophozoites through extrace llular matrixes might play a role in host tissue destruction. Trophozo ites degrade soluble fibronectin (FN) bound to their surface and adher e to substrate-bound FN, producing local degradation. FN proteolytic f ragments were used to determine the nature of adhesion and motility-pr omoting domains within the protein. The 70-kDa fragment (amino-termina l 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 He p II-binding fragments had no effect. The 70- and 120-kDa fragments al so stimulated directed migration and chemokinesis. Intact FN and the 2 5-kDa fragment showed lower stimulation. The Hep II-binding fragments had no activity. Results support previous evidence for distinct cell-s urface components as mediators of adhesion to FN and trophozoite motil ity and the potential importance of cell matrix recognition and degrad ation in their invasive behavior.