Recognition of the a Chain Carboxy-Terminal Heparin Binding Region of Fibronectin Involves Multiple Sites: Two Contiguous Sequences Act Independently to Promote Neural Cell Adhesion

• Published in: The Journal of cell biology 1990-12, Vol.111 (6), p.2733-2745
• Main Authors: Haugen, Patricia Keely, McCarthy, James B., Amy P. N. Skubitz, Furcht, Leo T., Letourneau, Paul C.
• Format: Article
• Language: English
• Subjects: Acetylglucosaminidase - metabolism; Amino Acid Sequence; Animals; Antibodies - isolation & purification; Binding Sites; Biological and medical sciences; Cell Adhesion; Cell interactions, adhesion; Cell Line; Cell lines; Cells; Embryonic cells; Fibronectins - metabolism; Fibronectins - physiology; Fundamental and applied biological sciences. Psychology; Heparin; Heparin - metabolism; Humans; Kinetics; Lymphocytes; Macromolecular Substances; Molecular and cellular biology; Molecular Sequence Data; Molecules; Neurites; Neuroblastoma; Neurons
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.111.6.2733

Cellular interactions with fibronectin-treated substrata have a complex molecular basis involving multiple domains. A carboxy-terminal cell and heparin binding region of fibronectin (FN) is particularly interesting because it is a strong promoter of neurite outgrowth and cell attachment. To further understand the molecular mechanisms of neuronal interactions with this region of FN, we screened two peptides from the 33-kD heparin binding fragment of the FN A chain, FN-C/H II (KNNQKSEPLIGRKKT) and CS1, for their ability to promote B104 neuroblastoma cell-substratum adhesion and neurite outgrowth. Both FN-C/H II and CS1 promoted B104 cell attachment in a concentration-dependent and saturable manner, with attachment to FN-C/H II exceeding attachment to CS1. In solution, both exogenous FN-C/H II or CS1 partially inhibited cell adhesion to the 33-kD fragment. Similar results were obtained with anti-FN-C/H II antibodies. In contrast, soluble GRGDSP did not affect B104 cell adhesion to FN-C/H II. These results indicate that both FN-C/H II and CS1 represent distinct, RGD-independent, cell adhesion-promoting sites active within the 33-kD fragment, and further define FN-C/H II as a novel neural recognition sequence in FN. B104 adhesion to FN-C/H II and CS1 differs in sensitivity to heparin, yet each peptide inhibited adhesion to the other peptide, suggesting cell adhesion is somehow related at the cellular level. Within the A chain 33-kD fragment, FN-C/H II and CS1 are contiguous, and might represent components of a larger domain with greater neurite-promoting activity since only the 33-kD fragment, and neither individual peptide, was effective at promoting B104 neurite outgrowth. These data further support the hypothesis that cell responses to FN are mediated by multiple sites involving both heparin-sensitive and -insensitive mechanisms.