p42/p44 mitogen-activated protein kinase activation is involved in prostaglandin F2alpha-induced interleukin-6 synthesis in osteoblasts.

Prostaglandin F2alpha (PGF2alpha) significantly induced p42/p44 mitogen-activated protein (MAP) kinase activity in osteoblast-like MC3T3-E1 cells. PD98059, a selective inhibitor of MAP kinase kinase, inhibited PGF2alpha-induced interleukin-6 (IL-6) synthesis as well as PGF2alpha-induced p42/p44 MAP kinase activation. PD98059 suppressed the IL-6 synthesis induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), a protein kinase C (PKC) activator, or NaF, an activator of heterotrimeric GTP-binding protein, as well as the p42/p44 MAP kinase activation by TPA or NaF. Calphostin C, a highly potent and specific inhibitor of PKC, inhibited the PGF2alpha-induced p42/p44 MAP kinase activity. These results strongly suggest that PKC-dependent p42/p44 MAP kinase activatioin is involved in PGF2alpha-induced IL-6 synthesis in osteoblasts.