Prostaglandin F_2α activates phospholipase D independently from activation of protein kinase C in osteoblast‐like cells

We previously reported that prostaglandin F_2α (PGF_2α) receptor is coupled to pertussis toxin (PTX)–sensitive GTP‐binding protein (G protein) in osteoblast‐like MC3T3‐E1 cells [Miwa et al. (1990): Biochem Biophys Res Commun 171:1229–1235]. In the present study, we examined the effect of PGF_2α on the activation of phosphatidylcholine‐hydrolyzing phospholipase D in MC3T3‐E1 cells. PGF_2α stimulated the formation of choline in a dose‐dependent manner in the range between 10 nM and 10 μM. The formation of choline was stimulated by 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA), a protein kinase C (PKC)–activating phorbol ester. 4α‐Phorbol 12,13‐didecanoate, a PKC‐nonactivating phorbol ester, had little effect on choline formation. The formation of choline stimulated by a combination of PGF_2α and TPA was additive. Staurosporine, an inhibitor for protein kinases, which inhibited the effect of TPA on choline formation, dose‐dependently enhanced the formation of choline induced by PGF_2α. NaF, an activator of G protein, stimulated the formation of choline. The formation of choline stimulated by a combination of PGF_2α and NaF was not additive. NaF‐induced formation of choline was dose‐dependently enhanced by staurosporine. PTX dose‐dependently inhibited the PGF_2α‐induced formation of choline. These results strongly suggest that PGF_2α activates phospholipase D independently from the activation of PKC in osteoblast‐like cells and PTX‐sensitive G protein is involved in the PGF_2α‐induced phospholipase D activation. © 1994 Wiley‐Liss, Inc.