Collagen receptors mediate early events in the attachment of epithelial (MDCK) cells.
Madin-Darby canine kidney (MDCK) cells kept in suspension culture for 12-15 hr displayed high-affinity binding sites for 125I-lathyritic (soluble) collagen (120,000/cell, KD = 30 nM) and preferred collagens types I and IV over laminin or fibronectin as substrates during the first hour of attachment. On the other hand, after 4 hr, attachment to all four substrates was equally efficient. Upon challenge with a collagen substrate, the high-affinity sites were rapidly recruited on it (T1/2 = 6 min). Their occupancy by soluble collagen triggered the exocytosis of a second large population of low-affinity collagen binding sites that included laminin and seems to be involved in a second cell-attachment mechanism. These results are compatible with a two-step model of MDCK cell attachment to the substrate: first, via high-affinity collagen binding sites, and second, via laminin of cellular origin.
Salas
P J
PJ
Department of Cell Biology and Anatomy, Cornell University Medical College, New York, New York 10021.
Vega-Salas
D E
DE
Rodriguez-Boulan
E
E
D000818:Animals; D002352:Carrier Proteins / Q000502:physiology*; D002448:Cell Adhesion; D002460:Cell Line; D003094:Collagen; D004847:Epithelial Cells; D005353:Fibronectins; D007700:Kinetics; D007797:Laminin; D038981:Receptors, Collagen; D011971:Receptors, Immunologic / Q000502:physiology*
D002352:Carrier Proteins; D005353:Fibronectins; D007797:Laminin; D038981:Receptors, Collagen; D011971:Receptors, Immunologic; D003094:Collagen