Osteoclast adhesion via integrin αv β3 to the bone matrix protein osteopontin (OPN) results in stimulation of bone resorption. We characterized an immediate signaling event that takes place upon osteoclast interaction with OPN. OPN binding to αv β3 results in the rapid production of the phosphoinositides (PtdInsP), including phosphatidylinositol triphosphate (PtdIns 3, 4, 5P3). Stimulation of 3, 4, 5-PtdInsP3 production by OPN was produced by increased activity of PtdInsP 3-OH kinase, which was found in immunoprecipitates formed by antibodies to integrin αv β3. The association of PtdIns 3-OH kinase with integrin may have been through association with c-src. The latter was present in immunoprecipitates formed by the antibodies to integrin αv β3, and src kinase was activated by OPN. These findings demonstrate a mechanism for rapid generation of cell signals upon matrix protein binding to αv β3, which resembles the mechanisms used by tyrosine kinase growth factor receptors.
|Number of pages||9|
|State||Published - Jul 1995|