Possible Coupling of Prostaglandin E2 Receptor with Pertussis Toxin-Sensitive Guanine Nucleotide-Binding Protein in Osteoblast-Like Cells

Abstract

In cloned osteoblast-like cells, MC3T3-E1, prostaglandin E₂ (PGE₂) stimulated the forma-tion of inositol phosphates in a dose-dependent manner in the range between 10 nM and 10μM. Pertussis toxin inhibited the effect of PGE₂ dose-dependently in the range between 1μg/ml and 1μg/ml. In the cell membranes, pertussis toxin catalyzed ADP-ribosylation of a protein with an M_r of about 40, 000. Pretreatment of membranes with 10μM PGE₂ in the presence of 2.5 mM MgCl₂ and 100μM GTP markedly attenuated this pertussis toxin-catalyzed ADP-ribosylation of the protein in a time-dependent manner. G₁₂ was detected in these cells by immunoblotting with purified anti-G₁₂αantibodies. The results indicate the possible coupling of PGE₂ signalling with pertussis toxin-sensitive GTP-binding protein, which is probably G₁₂, in osteoblast-like cells.