Latex beads as probes of cell surface-extracellular matrix interactions during chondrogenesis: evidence for a role for amino-terminal heparin-binding domain of fibronectin.
Fibronectin-rich mesenchymal condensations form at sites of incipient chondrogenesis in the developing vertebrate limb, and in cultures of limb bud mesenchyme. We have used 6 microns polystyrene latex beads coated with various substances as probes for adhesive interactions that may mediate the formation of these condensations. Beads coated with heparin, chondroitin sulfate, or poly L-lysine, that were mixed with limb bud mesenchymal cells were centripetally conveyed into fibronectin-rich regions of cell condensation over a period of several days. Beads coated with dextran sulfate remained uniformly dispersed throughout the cultures during the same period. A monoclonal antibody directed against the amino-terminal heparin-binding domain of fibronectin completely inhibited accumulation of heparin-coated beads at condensing foci, but monoclonal antibodies directed against the collagen- or cell-binding domains of fibronectin were not inhibitory. Accumulation of chondroitin sulfate- or poly L-lysine-coated beads at condensing foci was unaffected by the antibody against the fibronectin amino terminus. Peptides with the sequence arg-gly-asp-ser or gly-arg-gly-asp-ser, which inhibit adhesive interactions mediated by the integrin-binding domain of fibronectin, had no effect on conveyance or accumulation of heparin-coated beads, but the peptide with the sequence gly-arg-gly, a repeated motif in the amino-terminal heparin-binding domain was completely inhibitory. These findings indicate that the amino-terminal heparin-binding domain of fibronectin can, within a tissue microenvironment, interact adhesively with heparin-like components on the surfaces of polystyrene beads, and by implication, on mesenchymal cells themselves. This interaction may therefore be a component of the condensation-forming mechanism in chondrogenic mesenchyme.
Frenz
D A
DA
Department of Cell Biology and Anatomy, New York Medical College, Valhalla 10595.
Akiyama
S K
SK
Paulsen
D F
DF
Newman
S A
SA
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001665:Binding Sites; D002356:Cartilage / Q000196:embryology*; D002448:Cell Adhesion; D002462:Cell Membrane / Q000502:physiology*; D002478:Cells, Cultured; D002642:Chick Embryo; D002809:Chondroitin Sulfates / Q000378:metabolism; D005109:Extracellular Matrix / Q000502:physiology*; D005353:Fibronectins / Q000378:metabolism*; D006493:Heparin / Q000378:metabolism*; D008648:Mesoderm / Q000502:physiology*; D008863:Microspheres; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000494:pharmacology; D011107:Polylysine / Q000378:metabolism
D000911:Antibodies, Monoclonal; D005353:Fibronectins; D009842:Oligopeptides; D011107:Polylysine; D006493:Heparin; D002809:Chondroitin Sulfates