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

BackgroundOsteopontin (OPN) promotes the migration and adhesion of vascular smooth muscle cells (VSMCs) through cell surface receptor, integrin β3. In order to elucidate the signaling pathway by which OPN is involved in neointimal formation, we focused on integrin β3-focal adhesion kinase (FAK) upon VSMC migration.MethodsThe integrin β3 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 β3–FAK pathway in VSMC adhesion and migration induced with OPN was tested by the overexpression of FAK-related nonkinase and integrin β3 cytoplasmic domain.ResultsThe results showed that OPN increased integrin β3 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 β3 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 β3 and FAK expression induced by balloon injury, and neointimal thickening was inhibited.ConclusionsThese data indicate that integrin β3–FAK signaling modulates OPN-induced VSMC migration during neointimal formation.