Kassam A, Capone J P, Rachubinski R A
Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
J Biol Chem. 1999 Aug 6;274(32):22895-900. doi: 10.1074/jbc.274.32.22895.
Peroxisome proliferator-activated receptor alpha (PPARalpha) heterodimerizes with the 9-cis-retinoic acid receptor (RXRalpha) to bind to peroxisome proliferator-response elements (PPRE) present in the upstream regions of a number of genes involved in metabolic homeostasis. Among these genes are those encoding fatty acyl-CoA oxidase (AOx) and enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase (HD), the first two enzymes of the peroxisomal beta-oxidation pathway. Here we demonstrate that the orphan nuclear hormone receptor, RevErbalpha, modulates PPARalpha/RXRalpha- dependent transactivation in a response element-specific manner. In vitro binding analysis showed that RevErbalpha bound the HD-PPRE but not the AOx-PPRE. Determinants within the HD-PPRE required for RevErbalpha binding were distinct from those required for PPARalpha/RXRalpha binding. In transient transfections, RevErbalpha antagonized transactivation by PPARalpha/RXRalpha from an HD-PPRE luciferase reporter construct, whereas no effects were observed with an AOx-PPRE reporter construct. These data identify the HD gene as a target for RevErbalpha and illustrate cross-talk between the RevErbalpha and PPARalpha signaling pathways on the HD-PPRE. Our results suggest a novel role for RevErbalpha in regulating peroxisomal beta-oxidation.
过氧化物酶体增殖物激活受体α（PPARα）与9-顺式视黄酸受体（RXRα）形成异源二聚体，以结合存在于许多参与代谢稳态的基因上游区域的过氧化物酶体增殖物反应元件（PPRE）。这些基因包括编码脂肪酰辅酶A氧化酶（AOx）和烯酰辅酶A水合酶/3-羟酰基辅酶A脱氢酶（HD）的基因，它们是过氧化物酶体β-氧化途径的前两种酶。在这里，我们证明孤儿核激素受体RevErbalpha以反应元件特异性方式调节PPARα/RXRα依赖性反式激活。体外结合分析表明，RevErbalpha结合HD-PPRE但不结合AOx-PPRE。RevErbalpha结合所需的HD-PPRE内的决定簇与PPARα/RXRα结合所需的决定簇不同。在瞬时转染中，RevErbalpha拮抗来自HD-PPRE荧光素酶报告构建体的PPARα/RXRα的反式激活，而使用AOx-PPRE报告构建体未观察到影响。这些数据将HD基因鉴定为RevErbalpha的靶标，并说明了RevErbalpha和PPARα信号通路在HD-PPRE上的相互作用。我们的结果表明RevErbalpha在调节过氧化物酶体β-氧化中具有新作用。
