Cabrero Agatha, Jové Mireia, Planavila Anna, Merlos Manuel, Laguna Juan C, Vázquez-Carrera Manuel
Unitat de Farmacologia, Facultat de Farmàcia, Diagonal 643, E-08028 Barcelona, Spain.
Mol Pharmacol. 2003 Sep;64(3):764-72. doi: 10.1124/mol.64.3.764.
Cardiac expression of genes involved in fatty acid metabolism may suffer alterations depending on the substrate availability. We studied how troglitazone, an antidiabetic drug that selectively activates peroxisome proliferator-activated receptor gamma (PPARgamma), affected the expression of several of these genes. A single-day troglitazone administration (100 mg/kg/day) did not significantly alter plasma free fatty acids or triglyceride levels. In contrast, a 10-day period of troglitazone treatment significantly reduced plasma free fatty acids and triglyceride levels by 74% (P < 0.001) and 56% (P < 0.01), respectively. Cardiac mRNA expression of acyl-CoA oxidase (ACO) increased (8.3-fold induction) after 1-day troglitazone treatment, whereas after 10 days of treatment ACO mRNA levels were dramatically reduced (98% reduction, P < 0.02), as well as those of uncoupling protein 3 (41% reduction, P = 0.05). The mRNA expression of PPARalpha and several PPAR target genes, such as medium chain acyl-CoA dehydrogenase or fatty acid translocase were not altered after 10 days of troglitazone treatment, whereas muscle-type carnitine palmitoyltransferase I increased 1.7-fold (P < 0.05). The reduction in ACO expression in the hearts of 10-day troglitazone-treated mice was accompanied by an increase in the protein levels of the transcriptional repressor chicken ovalbumin upstream promoter transcription factor II (COUP-TF II). Electrophoretic mobility shift assays performed with COUP-TF II antibody to examine its interaction with a labeled peroxisome proliferator response element probe showed enhanced binding of COUP-TFII in cardiac nuclear extracts from troglitazone-treated mice for 10 days but not in the control nuclear extracts. Overall, the findings presented here show that 10 days of troglitazone treatment decreased expression of the ACO gene through a mechanism involving the transcriptional repressor COUP-TF II.
参与脂肪酸代谢的基因在心脏中的表达可能会因底物可用性而发生改变。我们研究了曲格列酮（一种选择性激活过氧化物酶体增殖物激活受体γ（PPARγ）的抗糖尿病药物）如何影响其中一些基因的表达。单日给予曲格列酮（100毫克/千克/天）并未显著改变血浆游离脂肪酸或甘油三酯水平。相比之下，为期10天的曲格列酮治疗显著降低了血浆游离脂肪酸和甘油三酯水平，分别降低了74%（P<0.001）和56%（P<0.01）。曲格列酮治疗1天后，酰基辅酶A氧化酶（ACO）的心脏mRNA表达增加（诱导8.3倍），而治疗10天后，ACO mRNA水平显著降低（降低98%，P<0.02），解偶联蛋白3的水平也降低（降低41%，P = 0.05）。曲格列酮治疗10天后，PPARα和几个PPAR靶基因（如中链酰基辅酶A脱氢酶或脂肪酸转运蛋白）的mRNA表达未发生改变，而肌肉型肉碱棕榈酰转移酶I增加了1.7倍（P<0.05）。在接受曲格列酮治疗10天的小鼠心脏中，ACO表达的降低伴随着转录抑制因子鸡卵清蛋白上游启动子转录因子II（COUP-TF II）蛋白水平的增加。用COUP-TF II抗体进行电泳迁移率变动分析，以检查其与标记的过氧化物酶体增殖物反应元件探针的相互作用，结果显示，在接受曲格列酮治疗10天的小鼠心脏核提取物中，COUP-TFII的结合增强，但在对照核提取物中未增强。总体而言，此处呈现的研究结果表明，为期10天的曲格列酮治疗通过一种涉及转录抑制因子COUP-TF II的机制降低了ACO基因的表达。
