title: RGD-independent cell adhesion to the carboxy-terminal heparin-binding fragment of fibronectin involves heparin-dependent and -independent activities.
abstract: Cell adhesion to extracellular matrix components such as fibronectin has a complex basis, involving multiple determinants on the molecule that react with discrete cell surface macromolecules. Our previous results have demonstrated that normal and transformed cells adhere and spread on a 33-kD heparin binding fragment that originates from the carboxy-terminal end of particular isoforms (A-chains) of human fibronectin. This fragment promotes melanoma adhesion and spreading in an arginyl-glycyl-aspartyl-serine (RGDS) independent manner, suggesting that cell adhesion to this region of fibronectin is independent of the typical RGD/integrin-mediated binding. Two synthetic peptides from this region of fibronectin were recently identified that bound [3H]heparin in a solid-phase assay and promoted the adhesion and spreading of melanoma cells (McCarthy, J. B., M. K. Chelberg, D. J. Mickelson, and L. T. Furcht. 1988. Biochemistry. 27:1380-1388). The current studies further define the cell adhesion and heparin binding properties of one of these synthetic peptides. This peptide, termed peptide I, has the sequence YEKPGSP-PREVVPRPRPGV and represents residues 1906-1924 of human plasma fibronectin. In addition to promoting RGD-independent melanoma adhesion and spreading in a concentration-dependent manner, this peptide significantly inhibited cell adhesion to the 33-kD fragment or intact fibronectin. Polyclonal antibodies generated against peptide I also significantly inhibited cell adhesion to the peptide, to the 33-kD fragment, but had minimal effect on melanoma adhesion to fibronectin. Anti-peptide I antibodies also partially inhibited [3H]heparin binding to fibronectin, suggesting that peptide I represents a major heparin binding domain on the intact molecule. The cell adhesion activity of another peptide from the 33-kD fragment, termed CS1 (Humphries, M. J., A. Komoriya, S. K. Akiyama, K. Olden, and K. M. Yamada. 1987. J. Biol. Chem., 262:6886-6892) was contrasted with peptide I. Whereas both peptides promoted RGD-independent cell adhesion, peptide CS1 failed to bind heparin, and exogenous peptide CS1 failed to inhibit peptide I-mediated cell adhesion. The results demonstrate a role for distinct heparin-dependent and -independent cell adhesion determinants on the 33-kD fragment, neither of which are related to the RGD-dependent integrin interaction with fibronectin.
authors.affiliation: University of Minnesota, Department of Laboratory Medicine and Pathology, Minneapolis.
authors.forename: J B
authors.initials: JB
authors.lastname: McCarthy
authors.forename: A P
authors.initials: AP
authors.lastname: Skubitz
authors.forename: Z
authors.initials: Z
authors.lastname: Qi
authors.forename: X Y
authors.initials: XY
authors.lastname: Yi
authors.forename: D J
authors.initials: DJ
authors.lastname: Mickelson
authors.forename: D J
authors.initials: DJ
authors.lastname: Klein
authors.forename: L T
authors.initials: LT
authors.lastname: Furcht
mesh_terms: D000595:Amino Acid Sequence; D002448:Cell Adhesion; D002460:Cell Line; D005353:Fibronectins / Q000378:metabolism*; D006493:Heparin / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008545:Melanoma; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009842:Oligopeptides / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000502:physiology
chemical_list: D005353:Fibronectins; D009842:Oligopeptides; D010446:Peptide Fragments; C047981:arginyl-glycyl-aspartic acid; D006493:Heparin