Cherrington Nathan J, Slitt Angela L, Maher Jonathan M, Zhang Xiao-Xue, Zhang Jun, Huang Wendong, Wan Yu-Jui Yvonne, Moore David D, Klaassen Curtis D
Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona, USA.
Drug Metab Dispos. 2003 Nov;31(11):1315-9. doi: 10.1124/dmd.31.11.1315.
We previously demonstrated that multidrug resistance protein 3 (Mrp3/ABCC3) is induced in rat liver by phenobarbital (PB) and several other microsomal enzyme inducers that induce cytochrome P450 2B (CYP2B). CYP2B is induced by constitutive androstane receptor (CAR)-retinoid X receptor (RXR) heterodimer binding to a phenobarbital-responsive promoter element in the CYP2B promoter. Hepatic mRNA levels of CYP2B and Mrp3 were measured in three models of altered CAR activity to determine whether CAR is also involved in the induction of Mrp3. In Wistar Kyoto rats, where males express higher CAR protein levels than females, the induction of CYP2B1/2 was significantly higher in males than in females by PB, diallyl sulfide, and trans-stilbene oxide but not oltipraz. Mrp3 was induced by each of these treatments, but in contrast to CYP2B1/2, to a similar magnitude in males and females. In male hepatocyte-specific RXRalpha-/- mice, CYP2B10 was not induced by diallyl sulfide or oltipraz but remained inducible by PB and trans-stilbene oxide after considering the decrease in basal CYP2B10 expression. Mrp3, however, was induced by PB, diallyl sulfide, trans-stilbene oxide and oltipraz in both wild-type and RXRalpha-/- mice. Additionally, constitutive expression of Mrp3 was significantly reduced in RXRalpha-/- mice. In CAR-/- mice, the robust induction of CYP2B10 by PB was completely absent. However, Mrp3 was equally induced both in wild-type and CAR-/- mice by PB. These data clearly demonstrate that induction of hepatic Mrp3 by PB and other microsomal enzyme inducers is CAR-independent and implies a role for RXRalpha in the constitutive expression of Mrp3.
我们之前证明，多药耐药蛋白3（Mrp3/ABCC3）在大鼠肝脏中可被苯巴比妥（PB）以及其他几种诱导细胞色素P450 2B（CYP2B）的微粒体酶诱导剂所诱导。CYP2B由组成型雄甾烷受体（CAR）-视黄酸X受体（RXR）异二聚体与CYP2B启动子中的苯巴比妥反应性启动子元件结合而被诱导。在三种CAR活性改变的模型中测量了CYP2B和Mrp3的肝脏mRNA水平，以确定CAR是否也参与Mrp3的诱导。在雄性表达的CAR蛋白水平高于雌性的Wistar Kyoto大鼠中，PB、二烯丙基硫醚和反式氧化茋对CYP2B1/2的诱导在雄性中显著高于雌性，但奥替普拉则不然。这些处理中的每一种都能诱导Mrp3，但与CYP2B1/2不同的是，雄性和雌性中的诱导程度相似。在雄性肝细胞特异性RXRα-/-小鼠中，二烯丙基硫醚或奥替普拉不能诱导CYP2B10，但在考虑基础CYP2B10表达降低后，PB和反式氧化茋仍可诱导其表达。然而，PB、二烯丙基硫醚、反式氧化茋和奥替普拉在野生型和RXRα-/-小鼠中均可诱导Mrp3。此外，RXRα-/-小鼠中Mrp3的组成型表达显著降低。在CAR-/-小鼠中，PB对CYP2B10的强烈诱导完全缺失。然而，PB在野生型和CAR-/-小鼠中对Mrp3的诱导程度相同。这些数据清楚地表明，PB和其他微粒体酶诱导剂对肝脏Mrp3的诱导不依赖于CAR，并暗示RXRα在Mrp3的组成型表达中起作用。
