C(2)-ceramide influences the expression and insulin-mediated regulation of cyclic nucleotide phosphodiesterase 3B and lipolysis in 3T3-L1 adipocytes.
Cyclic nucleotide phosphodiesterase (PDE) 3B plays an important role in the antilipolytic action of insulin and, thereby, the release of fatty acids from adipocytes. Increased concentrations of circulating fatty acids as a result of elevated or unrestrained lipolysis cause insulin resistance. The lipolytic action of tumor necrosis factor (TNF)-alpha is thought to be one of the mechanisms by which TNF-alpha induces insulin resistance. Ceramide is the suggested second messenger of TNF-alpha action, and in this study, we used 3T3-L1 adipocytes to investigate the effects of C(2)-ceramide (a short-chain ceramide analog) on the expression and regulation of PDE3B and lipolysis. Incubation of adipocytes with 100 micromol/l C(2)-ceramide (N-acetyl-sphingosine) resulted in a time-dependent decrease of PDE3B activity, accompanied by decreased PDE3B protein expression. C(2)-ceramide, in a time- and dose-dependent manner, stimulated lipolysis, an effect that was blocked by H-89, an inhibitor of protein kinase A. These ceramide effects were prevented by 20 micromol/l troglitazone, an antidiabetic drug. In addition to downregulation of PDE3B, the antilipolytic action of insulin was decreased by ceramide treatment. These results, together with data from other studies on PDE3B and lipolysis in diabetic humans and animals, suggest a novel pathway by which ceramide induces insulin resistance. Furthermore, PDE3B is demonstrated to be a target for troglitazone action in adipocytes.
Mei
Jie
J
Section for Molecular Signalling, Department of Cell and Molecular Biology, Lund University, Sweden. jie.mei@medkem.lu.se
Holst
Lena Stenson
LS
Landström
Tova Rahn
TR
Holm
Cecilia
C
Brindley
David
D
Manganiello
Vincent
V
Degerman
Eva
E
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000032:analysis / Q000378:metabolism*; D016475:3T3 Cells; D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002839:Chromans / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology*; D007333:Insulin Resistance; D007546:Isoquinolines / Q000494:pharmacology; D008066:Lipolysis / Q000187:drug effects*; D051379:Mice; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D013449:Sulfonamides; D013844:Thiazoles / Q000494:pharmacology; D045162:Thiazolidinediones; D014157:Transcription Factors / Q000235:genetics; D000077288:Troglitazone; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D002839:Chromans; D004791:Enzyme Inhibitors; D007328:Insulin; D007546:Isoquinolines; C064769:N-acetylsphingosine; D018160:Receptors, Cytoplasmic and Nuclear; D013449:Sulfonamides; D013844:Thiazoles; D045162:Thiazolidinediones; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D017868:Cyclic AMP-Dependent Protein Kinases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; C517293:Pde3b protein, mouse; D000077288:Troglitazone; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; D013110:Sphingosine