Arachidonic acid-dependent inhibition of adipocyte differentiation requires PKA activity and is associated with sustained expression of cyclooxygenases

• Published in: Journal of lipid research Vol. 44; no. 12; pp. 2320 - 2330
• Main Authors: Petersen, Rasmus K., J⊘rgensen, Claus, Rustan, Arild C., Fr⊘yland, Livar, Muller-Decker, Karin, Furstenberger, Gerhard, Berge, Rolf K., Kristiansen, Karsten, Madsen, Lise
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-12-2003; Elsevier
• Subjects: 3T3-L1 Cells; Acyltransferases - metabolism; adipocytes; Adipocytes - cytology; Adipocytes - drug effects; Adipocytes - enzymology; Animals; arachidonic acid; Arachidonic Acid - pharmacology; cAMP-dependent protein kinase; CCAAT/enhancer-binding protein; cell differentiation; Cell Differentiation - drug effects; Cyclic AMP - metabolism; Cyclic AMP-Dependent Protein Kinases - metabolism; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors - pharmacology; diacylglycerol acyltransferase; Diacylglycerol O-Acyltransferase; Fatty Acids - biosynthesis; Fatty Acids - metabolism; Indomethacin - pharmacology; Isoenzymes - antagonists & inhibitors; Isoenzymes - metabolism; MAP Kinase Signaling System - drug effects; Mice; mitogen-activated protein kinase; Mitogen-Activated Protein Kinases - metabolism; oxygenases; peroxisome proliferator-activated receptor; Prostaglandin-Endoperoxide Synthases - metabolism; protein kinase A; protein kinases; Triglycerides - metabolism; mitogen-activated protein kinase; peroxisome proliferator-activated receptor; CCAAT/enhancer-binding protein; diacylglycerol acyltransferase; protein kinase A
• ISSN: 0022-2275; 1539-7262
• DOI: 10.1194/jlr.M300192-JLR200

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.