Blockade of integrin β3-FAK signaling pathway activated by osteopontin inhibits neointimal formation after balloon injury

Background: Osteopontin (OPN) promotes the migration and adhesion of vascular smooth muscle cells (VSMCs) through cell surface receptor, integrin beta 3. In order to elucidate the signaling pathway by which OPN is involved in neointimal formation, we focused on integrin beta 3-focal adhesion kinase (FAK) upon VSMC migration. Methods: The integrin 3 and FAK expression in VSMC and in neointima was detected by Western blot and immunohistochemistry staining. FAK phosphorylation induced by OPN was verified using a linear OPN 13 peptide containing RGD motif and anti-OPN antibody. The role of integrin beta 3-FAK pathway in VSMC adhesion and migration induced with OPN was tested by the overexpression of FAK-related nonkinase and integrin beta 3 cytoplasmic domain. Results: The results showed that OPN increased integrin beta 3 expression and induced rapid and transient FAK phosphorylation. Inhibition of the phosphorylation of FAK significantly suppressed VSMC migration induced by OPN. Similarly, blockade of the interaction of integrin beta 3 with OPN inhibited VSMC adhesion induced by OPN. The experiment, in vivo, demonstrated that OPN expression level was consistent with neointimal thickening. Administration of anti-OPN antibody for blocking OPN function suppressed integrin beta 3 and FAK expression induced by balloon injury, and neointimal thickening was inhibited. Conclusions: These data indicate that integrin beta 3-FAK signaling modulates OPN-induced VSMC migration during neointimal formation. (C) 2007 Published by Elsevier Inc.