Interaction of fibronectin-coated beads with attached and spread fibroblasts. Binding, phagocytosis, and cytoskeletal reorganization.
After 15 min incubations, binding of 0.8-, 6-, and 16-microns fibronectin-coated latex beads occurred primarily at the margins of chick embryo fibroblasts that previously were attached and spread on fibronectin-coated glass coverslips. Extensive phagocytosis of the smallest beads and some phagocytosis of the larger beads occurred within 2 h. Following binding of the 16-micron beads, there were no changes in overall cell shape or in the distribution of several cytoskeletal proteins. There was, however, a local accumulation of actin and alpha-actinin patches adjacent to the sites where the beads were bound. The formation of alpha-actinin patches could be detected with 6- or 16-microns beads shortly after initial bead binding to the cells, but a similar reorganization of alpha-actinin in response to the binding of 0.8-micron beads was not detected. The patches of alpha-actinin appeared to be associated with membrane ruffles, since such structures were observed by scanning electron microscopy (SEM) to be sites of cell interaction with 6- but not 0.8-micron beads. Also, two other cytoskeletal proteins normally absent from membrane ruffles, tropomyosin and vinculin, were not detected at the sites of cell-bead interaction. No reorganization of vinculin at the cell-bead interaction sites was observed even when the 16-microns beads remained bound at the cell surfaces for up to 6 h. Nevertheless, prominent vinculin plaques were observed at the marginal attachment sites on the ventral cell surfaces. Consequently, formation of mature focal adhesions may be restricted to linear regions of cell-substratum interaction.
Grinnell
F
F
Geiger
B
B
D000185:Actinin / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D002448:Cell Adhesion; D002462:Cell Membrane / Q000648:ultrastructure; D002642:Chick Embryo; D003599:Cytoskeleton / Q000648:ultrastructure*; D005347:Fibroblasts / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007840:Latex; D008297:Male; D008863:Microspheres; D009124:Muscle Proteins / Q000378:metabolism; D010587:Phagocytosis; D014335:Tropomyosin / Q000378:metabolism; D016596:Vinculin
D000199:Actins; D005353:Fibronectins; D007840:Latex; D009124:Muscle Proteins; D014335:Tropomyosin; D000185:Actinin; D016596:Vinculin