ROLE OF GLUCOCORTICOID RECEPTOR AND CONSTITUTIVE ANDROSTANE RECEPTOR
ROLE OF GLUCOCORTICOID RECEPTOR AND CONSTITUTIVE ANDROSTANE RECEPTOR
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发表时间：
2002
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通讯作者：
S. Gerbal-Chaloin;M. Daujat;J. Pascussi;L. Pichard‐Garcia;M. Vilarem;P. Maurel
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作者：
S. Gerbal-Chaloin;M. Daujat;J. Pascussi;L. Pichard‐Garcia;M. Vilarem;P. Maurel
尽管细胞色素 P450 2C9 (CYP2C9) 是成人肝脏中表达的主要 CYP，但其调节机制尚不清楚。在之前的工作中，我们已经证明，CYP2C9 在人原代肝细胞中可以被地塞米松、利福平和苯巴比妥等异生素诱导。这项工作的目的是研究控制 CYP2C9 诱导表达的分子机制。在存在各种激素核受体的情况下对 CYP2C9 调节区（21 至 2088）的删除分析表明存在两种功能反应元件，即糖皮质激素受体反应元件（1648/1684）和组成型雄甾烷受体反应元件（CAR，1783/1856）。其中每一种都通过共转染实验、定向诱变、凝胶位移测定以及对特定拮抗剂 RU486 和雄甾烷醇的反应来表征。通过这些实验，我们在 1662/1676 定位了一个糖皮质激素反应元件不完全回文，以及在 1803/1818 定位了一个 DR4 基序，分别被人糖皮质激素受体和 hCAR 和孕烷 X 受体识别和反式激活。这些功能元件的鉴定为地塞米松（亚微摩尔浓度）以及苯巴比妥和利福平分别诱导 CYP2C9 提供了合理的机制基础。因此，CYP2C9 似乎是主要的糖皮质激素反应基因，此外，该基因还可能通过 CAR/孕烷 X 受体激活而被异生素诱导。
Although cytochrome P450 2C9 (CYP2C9) is a major CYP expressed in the adult human liver, its mechanism of regulation is poorly known. In previous work, we have shown that CYP2C9 is inducible in primary human hepatocytes by xenobiotics including dexamethasone, rifampicin, and phenobarbital. The aim of this work was to investigate the molecular mechanism(s) controlling the inducible expression of CYP2C9. Deletional analysis of CYP2C9 regulatory region (21 to 2088) in the presence of various hormone nuclear receptors suggested the presence of two functional response elements, a glucocorticoid receptor-responsive element (1648/1684) and a constitutive androstane receptor-responsive element (CAR, 1783/1856). Each of these were characterized by co-transfection experiments, directed mutagenesis, gel shift assays, and response to specific antagonists RU486 and androstanol. By these experiments we located a glucocorticoid-responsive element imperfect palindrome at 1662/1676, and a DR4 motif at 1803/1818 recognized and transactivated by human glucocorticoid receptor and by hCAR and pregnane X receptor, respectively. Identification of these functional elements provides rational mechanistic basis for CYP2C9 induction by dexamethasone (submicromolar concentrations), and by phenobarbital and rifampicin, respectively. CYP2C9 appears therefore to be a primary glucocorticoid-responsive gene, which in addition, may be induced by xenobiotics through CAR/pregnane X receptor activation.