Characterization of the signal transduction of prostaglandin E receptor EP1 subtype in cDNA-transfected Chinese hamster ovary cells.
We examined the signal transduction of mouse prostaglandin E receptor EP1 subtype using Chinese hamster ovary cells stably expressing the cloned EP1. Sulprostone, an EP1 agonist, induced a rapid increase in intracellular Ca2+ concentration in the EP1-expressing cells. Most of the increase was abolished by removal of extracellular Ca2+, and was insensitive to U-73122, a phospholipase C inhibitor. Sulprostone stimulated phosphatidylinositol hydrolysis, but this stimulation was abolished by removal of extracellular Ca2+, indicating that EP1-stimulated phosphatidylinositol hydrolysis is the result of extracellular Ca2+ influx. Thus, the signal transduction of EP1 is extracellular Ca2+ entry through a pathway independent of phospholipase C activation. We further examined the regulation of the signal transduction of EP1 having potential phosphorylation sites for either protein kinase C or protein kinase A. Short-term exposure of the cells to 12-O-tetradecanoylphorbol 13-acetate (TPA) completely suppressed the sulprostone-induced increase in intracellular Ca2+ concentration, while forskolin or dibutyryl cAMP did not affect it, suggesting that protein kinase C but not protein kinase A is involved in the regulation of the EP1 signal transduction. Furthermore, long-term exposure to TPA decreased PGE2 protein kinase A is involved in the regulation of the EP1 signal transduction. Furthermore, long-term exposure to TPA decreased PGE2 binding activity of EP1 due to the reduction of the EP1 mRNA level. Protein kinase C induces short- and long-term desensitization of EP1.
Katoh
H
H
Department of Physiological Chemistry, Faculty of Pharmaceutical Sciences, Kyoto University, Japan.
Watabe
A
A
Sugimoto
Y
Y
Ichikawa
A
A
Negishi
M
M
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D015232:Dinoprostone / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D015536:Down-Regulation; D006150:Guanine Nucleotides / Q000494:pharmacology; D051379:Mice; D010716:Phosphatidylinositols / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D018078:Receptors, Prostaglandin E / Q000819:agonists / Q000502:physiology*; D011994:Recombinant Proteins; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D006150:Guanine Nucleotides; D010716:Phosphatidylinositols; D018078:Receptors, Prostaglandin E; D011994:Recombinant Proteins; C016767:sulprostone; D011493:Protein Kinase C; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate