Characterization of prostaglandin F2 alpha receptor of mouse 3T3 fibroblasts and its functional expression in Xenopus laevis oocytes.

Prostaglandin (PG) F2 alpha increased [3H]thymidine incorporation into quiescent NIH 3T3 cells, stimulated phosphoinositide breakdown, and raised intracellular Ca2+ concentration ([Ca2+]i) in a dose-dependent manner with ED50 values of 2.0 x 10(-8) M, 4.6 x 10(-8) M, and 7.5 x 10(-8) M, respectively. The increase in [3H]thymidine incorporation with PGF2 alpha was additive with that seen with epidermal growth factor (EGF) or insulin. The peak [Ca2+]i increase with PGF2 alpha was still obvious in the absence of extracellular Ca2+ and was insensitive to islet activating protein (IAP) pretreatment. Membranes prepared from NIH 3T3 cells exhibited a specific binding for PGF2 alpha, which was sensitive to GTP gamma S but not sensitive to IAP pretreatment. Xenopus laevis oocytes injected with NIH 3T3 cell mRNA between 18S and 28S rRNA fractionated by sucrose gradient, expressed a PGF2 alpha-specific Cl- current when examined by voltage clamp. This Cl- current was also insensitive to IAP pretreatment and not affected by extracellular Ca2+ concentration ([Ca2+]o). These results indicate 1) that the NIH 3T3 cells expressed a specific PGF2 alpha receptor which is linked to phosphoinositide-specific phospholipase C (PLC) activation and to mobilization of Ca2+ via an IAP-insensitive G-protein(s), 2) that this PGF2 alpha receptor may play an active role in the proliferation of NIH 3T3 cells, and 3) that this PGF2 alpha receptor can be expressed in the oocyte system.