Osteopontin stimulates gelsolin-associated phosphoinositide levels and phosphatidylinositol triphosphate-hydroxyl kinase

Meenakshi Chellaiah, Keith Hruska

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103 Scopus citations


Based on previous studies demonstrating activation of phosphatidylinositol 3-hydroxyl kinase (PI3-kinase) and stimulation of a change in cell shape, we examined the effect of osteopontin on the association of phospholipids with gelsolin, an actin-capping/severing protein. Osteopontin stimulated a rapid increase in phosphatidylinositol bisphosphate and phosphatidylinositol triphosphate levels associated with gelsolin in Triton-soluble fractions of cell lysates. The increased levels of phosphatidylinositol triphosphate associated with gelsolin were due to stimulation of PI3-kinase activity associated with gelsolin in the Triton-soluble fractions, and they were blocked by the PI3-kinase inhibitor wortmannin. Osteopontin stimulated translocation of PI3-kinase from the Triton-insoluble to Triton-soluble gelsolin. Osteopontin also decreased Triton-soluble gelsolin/actin complexes consistent with actin uncapping, and increased F-actin levels, which were also blocked by wortmannin. The osteopontin effects were mediated through binding to the α(v)3 integrin. Taken together, our studies indicate that osteopontin/α(v)β3-mediated changes in gelsolin-associated phosphoinositide levels and PI3-kinase activity are related to stimulation of F-actin formation in osteoclasts.

Original languageEnglish
Pages (from-to)743-753
Number of pages11
JournalMolecular biology of the cell
Issue number5
StatePublished - May 1996


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