title: Regulation of 3T3-L1 fibroblast differentiation by prostacyclin (prostaglandin I2).
abstract: Prostaglandin biosynthesis and prostaglandin-stimulated cyclic AMP accumulation were studied in 3T3-L1 fibroblasts as they differentiated into adipocytes. Incubation of 3T3-L1 membranes with [1-14C]prostaglandin H2, and subsequent radio-TLC analysis, showed that prostacyclin (prostaglandin I2) is the principal enzymatically synthesized prostaglandin in this cell line. Confirmation of the radiochemical data was obtained by demonstrating the presence of 6-keto-prostaglandin F1 alpha, the stable hydrolysis product of prostaglandin I2, by gas chromatography-mass spectrometry. In support of previous work, indomethacin, the prostaglandin endoperoxide synthetase (EC 1.14.99.1) inhibitor, accelerated 3T3-L1 differentiation. More importantly, the incubation of 3T3-L1 cells with insulin and the prostaglandin I2 synthetase inhibitor 9,11-azoprosta-5,13-dienoic acid (azo analog I) also enhanced the rate of cellular differentiation, even though this compound does not inhibit the synthesis of other prostaglandins. The repeated addition of exogenous prostaglandin I2 to 3T3-L1 cells inhibited insulin- and indomethacin-mediated differentiation. When 3T3-L1 cells were exposed to various prostaglandins and the cyclic AMP levels were measured, prostaglandin I2 proved to be the most potent stimulator of cyclic AMP accumulation, followed by prostaglandin E1 greater than prostaglandin H2 much greater than prostaglandin E2, while prostaglandin D2 was inactive. As 3T3-L1 cells differentiate, the ability of prostaglandin I2 or prostaglandin H2 to stimulate cyclic AMP accumulation progressively diminishes. It is suggested that 3T3-L1 differentiation may be controlled by the rate of prostaglandin I2 synthesis and/or sensitivity of the adenylate cyclase to prostaglandin I2.
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism*; D011464:Epoprostenol / Q000096:biosynthesis / Q000494:pharmacology*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D007213:Indomethacin / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D051379:Mice; D011453:Prostaglandins / Q000096:biosynthesis* / Q000494:pharmacology*; D011463:Prostaglandins H / Q000494:pharmacology
chemical_list: D007328:Insulin; D011453:Prostaglandins; D011463:Prostaglandins H; D011464:Epoprostenol; D000242:Cyclic AMP; D007213:Indomethacin