Arachidonic acid-dependent inhibition of adipocyte differentiation requires PKA activity and is associated with sustained expression of cyclooxygenases.
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.
Petersen
Rasmus K
RK
Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark.
Jørgensen
Claus
C
Rustan
Arild C
AC
Frøyland
Livar
L
Muller-Decker
Karin
K
Furstenberger
Gerhard
G
Berge
Rolf K
RK
Kristiansen
Karsten
K
Madsen
Lise
L
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
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