CELL-ADHESION RECEPTORS FOR NATIVE AND DENATURED TYPE-I COLLAGENS AND FIBRONECTIN IN RABBIT ARTERIAL SMOOTH-MUSCLE CELLS IN CULTURE

Cell adhesion molecules serve as specific cell surface receptors for extracellular matrices and contribute to the attachment, spreading, proliferation, and differentiation of vascular cells. We examined the cell adhesion receptors and binding sites on native type I collagen, heat-denatured type I collagen, and fibronectin in rabbit arterial smooth muscle cells (SMC) in culture. On fibronectin, anti-alpha 3 beta 1 and anti-alpha 5 beta 1 integrin antibodies and the synthetic peptide GRGDSP (Gly-Arg-Gly-Asp-Ser-Pro) significantly inhibited the attachment and spreading of rabbit SMC after 1 and 24 h of culture, while anti-alpha 1 beta 1 inhibited attachment and spreading only after 1 h. In contrast, the attachment and spreading of the cells on native type I collagen were mediated by alpha 1 beta 1 integrin and the cell-binding sequence which did not contain RGD (Arg-Gly-Asp) and DGEA (Asp-Gly-Glu-Ala) after both 1 and 24 h. On heat-denatured type I collagen, alpha 2 beta 1 integrin mediated the cell attachment and spreading after 1 and 24 h and DGEA served as a recognition site for the alpha 2 beta 1 integrin. alpha 1 beta 1 and alpha 3 beta 1 integrins affected only the initial adherence (1 h after plating) of the cells to denatured type I collagen. These findings suggest that rabbit SMC in culture can recognize the native and unfolded triple helical structures of type I collagen by interacting with the collagen fibril-binding receptor (alpha 1 beta 1 integrin) and collagen peptide-binding receptors (alpha 2 beta 1 and alpha 3 beta 1 integrins). Moreover, alpha 1 beta 1 integrin may mediate the initial adherence to each substrate. (C) 1994 Academic Press, Inc.