title: Arachidonic acid-dependent inhibition of adipocyte differentiation requires PKA activity and is associated with sustained expression of cyclooxygenases.
abstract: Arachidonic acid inhibits adipocyte differentiation of 3T3-L1 cells via a prostaglandin synthesis-dependent pathway. Here we show that this inhibition requires the presence of a cAMP-elevating agent during the first two days of treatment. Suppression of protein kinase A activity by H-89 restored differentiation in the presence of arachidonic acid. Arachidonic acid treatment led to a prolonged activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), and suppression of ERK1/2 activity by the addition of U0126 rescued differentiation. Upon induction of differentiation, expression of cyclooxygenase-2 (COX-2) was transiently induced and then declined, whereas COX-1 expression declined gradually as differentiation progressed. Treatment with arachidonic acid led to sustained expression of COX-1 and COX-2. Omission of a cAMP-elevating agent or addition of H-89 or U0126 prevented sustained expression of COX-2. Unexpectedly, we observed that selective COX-1 or COX-2 inhibitors rescued adipocyte differentiation in the presence of arachidonic acid as effectively as did the nonselective COX-inhibitor indomethacin. De novo fatty acid synthesis, diacylglycerol acyltransferase (DGAT) activity, and triacylglycerol accumulation were repressed in cells treated with arachidonic acid. Indomethacin restored DGAT activity and triacylglycerol accumulation without restoring de novo fatty acid synthesis, resulting in an enhanced incorporation of arachidonic acid into cellular triacylglycerols.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark.
authors.forename: Rasmus K
authors.initials: RK
authors.lastname: Petersen
authors.forename: Claus
authors.initials: C
authors.lastname: Jørgensen
authors.forename: Arild C
authors.initials: AC
authors.lastname: Rustan
authors.forename: Livar
authors.initials: L
authors.lastname: Frøyland
authors.forename: Karin
authors.initials: K
authors.lastname: Muller-Decker
authors.forename: Gerhard
authors.initials: G
authors.lastname: Furstenberger
authors.forename: Rolf K
authors.initials: RK
authors.lastname: Berge
authors.forename: Karsten
authors.initials: K
authors.lastname: Kristiansen
authors.forename: Lise
authors.initials: L
authors.lastname: Madsen
mesh_terms: D041721:3T3-L1 Cells; D000217:Acyltransferases / Q000378:metabolism; D017667:Adipocytes / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology; D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects*; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D051048:Diacylglycerol O-Acyltransferase; D005227:Fatty Acids / Q000096:biosynthesis / Q000378:metabolism; D007213:Indomethacin / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism
chemical_list: D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D005227:Fatty Acids; D007527:Isoenzymes; D014280:Triglycerides; D016718:Arachidonic Acid; D000242:Cyclic AMP; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D000217:Acyltransferases; C494882:Dgat1 protein, mouse; D051048:Diacylglycerol O-Acyltransferase; D017868:Cyclic AMP-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D007213:Indomethacin