Laminin contains multiple
oligopeptide motifs to promote cell adhesion and migration. One of these motifs is
YIGSR within the B1 chain. We reconstituted the cell-adhesive activity of
YIGSR motif by grafting it onto a truncated form of the
Staphylococcal protein A (designated tSPA) via cassette mutagenesis. When coated on a
polystyrene surface, the
YIGSR-grafted tSPA (
YIGSR-tSPA) promoted attachment and spreading of mouse
melanoma and human
rhabdomyosarcoma cells, but not of hamster fibroblasts. The cell-adhesive activity of
YIGSR-tSPA was abolished by amino acid substitution or scrambling of the inserted
YIGSR sequence.
Divalent cations Mn2+ and Mg2+, but not Ca2+, promoted the cell adhesion to
YIGSR-tSPA. Interestingly, the
YIGSR-tSPA-mediated cell adhesion was barely inhibited by the linear
peptide CDPGYIGSR-NH2, but was strongly inhibited by the
cyclic peptide CDPGYIGSRC and another
peptide PEILDVPST, which is a specific inhibitor for
integrin alpha 4 beta 1. Among various anti-
integrin antibodies, anti-alpha 4 and anti-beta 1
antibodies specifically inhibited the cell adhesion to
YIGSR-tSPA. In support of these observations, adhesion of
rhabdomyosarcoma cells to intact
laminin was also partially inhibited by synthetic PEILDVPST
peptide and anti-alpha 4 antibody. These results, taken together, indicate that the
YIGSR motif exerts its cell-adhesive activity through interaction with
integrin alpha 4 beta 1.