title: Down-regulation of uncoupling protein-3 and -2 by thiazolidinediones in C2C12 myotubes.
abstract: Uncoupling proteins (UCPs) are mitochondrial membrane proton transporters that uncouple respiration from oxidative phosphorylation by dissipating the proton gradient across the membrane. We studied the direct effect of several peroxisome proliferator-activated receptor (PPAR) ligands on UCP-3 and UCP-2 mRNA expression in C2C12 myotubes for 24 h. In the absence of exogenous fatty acids, treatment of C2C12 cells with a selective PPARalpha activator (Wy-14,643) or a non-selective PPAR activator (bezafibrate) did not affect the expression of UCP-3 mRNA levels, whereas UCP-2 expression was slightly increased. In contrast, troglitazone, a thiazolidinedione which selectively activates PPARgamma, strongly decreased UCP-3 and UCP-2 mRNA levels. Another thiazolidinedione, ciglitazone, had the same effect, but to a lower extent, suggesting that PPARgamma activation is involved. Further, the presence of 0.5 mM oleic acid strongly increased UCP-3 mRNA levels and troglitazone addition failed to block the effect of this fatty acid. The drop in UCP expression after thiazolidinedione treatment correlated well with a reduction in PPARalpha mRNA levels produced by this drug, linking the reduction in PPARalpha mRNA levels with the down-regulation of UCP mRNA in C2C12 myotubes after thiazolidinedione treatment.
authors.affiliation: Unidad de Farmacología, Departamento de Farmacología y Química Terapéutica, Facultad de Farmacia, Universidad de Barcelona, Diagonal 643, E-08028, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Cabrero
authors.forename: M
authors.initials: M
authors.lastname: Alegret
authors.forename: R M
authors.initials: RM
authors.lastname: Sánchez
authors.forename: T
authors.initials: T
authors.lastname: Adzet
authors.forename: J C
authors.initials: JC
authors.lastname: Laguna
authors.forename: M
authors.initials: M
authors.lastname: Vázquez
mesh_terms: D042964:Acyl-CoA Dehydrogenase; D000818:Animals; D000069059:Atorvastatin; D001629:Bezafibrate / Q000494:pharmacology; D002334:Carnitine O-Palmitoyltransferase / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics*; D002460:Cell Line; D002784:Cholesterol / Q000494:pharmacology; D002839:Chromans / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects*; D044943:Fatty Acid Desaturases / Q000235:genetics; D006538:Heptanoic Acids / Q000494:pharmacology; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007473:Ion Channels; D008024:Ligands; D026901:Membrane Transport Proteins; D051379:Mice; D024101:Mitochondrial Proteins; D009132:Muscles / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D019301:Oleic Acid / Q000494:pharmacology; D020025:Peroxisome Proliferators / Q000494:pharmacology; D011506:Proteins / Q000235:genetics*; D011743:Pyrimidines / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology*; D045162:Thiazolidinediones; D014157:Transcription Factors / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D014226:Triazenes / Q000494:pharmacology; D000077288:Troglitazone; D000071246:Uncoupling Protein 2; D000071247:Uncoupling Protein 3
chemical_list: D002352:Carrier Proteins; D002839:Chromans; D006538:Heptanoic Acids; D007004:Hypoglycemic Agents; D007473:Ion Channels; D008024:Ligands; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D020025:Peroxisome Proliferators; D011506:Proteins; D011743:Pyrimidines; D011758:Pyrroles; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D013844:Thiazoles; D045162:Thiazolidinediones; D014157:Transcription Factors; D014226:Triazenes; C000604390:Ucp2 protein, mouse; C000604393:Ucp3 protein, mouse; D000071246:Uncoupling Protein 2; D000071247:Uncoupling Protein 3; D019301:Oleic Acid; C034613:triacsin C; C006253:pirinixic acid; D002784:Cholesterol; D000069059:Atorvastatin; C089946:2,4-thiazolidinedione; D044943:Fatty Acid Desaturases; D042964:Acyl-CoA Dehydrogenase; D002334:Carnitine O-Palmitoyltransferase; D000077288:Troglitazone; C039671:ciglitazone; D001629:Bezafibrate