THE ROLE OF CARBOXY-TERMINAL GLYCOSAMINOGLYCAN-BINDING DOMAIN OF VITRONECTIN IN CYTOSKELETAL ORGANIZATION AND MIGRATION OF ENDOTHELIAL-CELLS

Vitronectin is a major cell adhesion molecule present in the subendoth elial matrix that mediates the attachment and spreading of a variety o f cells, The carboxy-terminal end of vitronectin has a consensus seque nce for glycosaminoglycan-binding. To define the functional role of th is domain, we generated fragments of vitronectin that lack the glycosa minoglycan-binding domain by formic acid cleavage of plasma-derived vi tronectin. In addition, we also generated similar recombinant fragment s of vitronectin as glutathione S-transferase fusion proteins in E. co li. These fragments were tested for their ability to support the adhes ion of human umbilical Vein endothelial cells. These fragments promote d endothelial cell adhesion, reaching half maximal activity at 2-5 mu g/well compared to plasma-derived vitronectin which reached at 0.2 mu g/well. However, the cells that adhered to these fragments did not dev elop well-formed focal adhesion plaques and actin stress fibers. In ad dition, these fragments were poorly chemotactic for endothelial cell m igration when compared to intact plasma-derived vitronectin in a modif ied Boyden chamber assay. The present studies show that carboxy-termin al glycosaminoglycan-binding domain of vitronectin is essential for pr oper cytoskeletal organization and migration of endothelial cells on v itronectin substratum.