OSTEOPONTIN INVOLVEMENT IN INTEGRIN-MEDIATED CELL SIGNALING AND REGULATION OF EXPRESSION OF ALKALINE-PHOSPHATASE DURING EARLY DIFFERENTIATION OF UMR CELLS

To clarify the function of osteopontin in osteoblast differentiation, We have examined the signal transduction pathway in an osteoblastic ce ll line (UMR106-6) bound to osteopontin, fibronectin, vitronectin and collagen type I surfaces, This,vas done by investigating the productio n and autophosphorylation of focal adhesion kinase (FAK) and the expre ssion of alkaline phosphatase (ALP) at the transcription level, Result s suggest that osteopontin was not only responsible for the autophosph orylation of FAK but regulated the expression of ALP, which nas strong ly correlated with FAK activity. These results suggest that osteoponti n might act as a trigger in the early differentiation of osteoblasts, (C) 1997 Federation of European Biochemical Societies.