Up-Regulation of UDP-Glucuronosyltransferase (UGT) 1A4 by 17β-Estradiol: A Potential Mechanism of Increased Lamotrigine Elimination in Pregnancy
Up-Regulation of UDP-Glucuronosyltransferase (UGT) 1A4 by 17β-Estradiol: A Potential Mechanism of Increased Lamotrigine Elimination in Pregnancy
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DOI：
10.1124/dmd.109.026609
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发表时间：
2009-09-01
影响因子：
3.9
通讯作者：
Jeong, Hyunyoung
中科院分区：
文献类型：
--
作者：
Chen, Huiqing;Yang, Kyunghee;Jeong, Hyunyoung
拉莫三嗪（一种孕妇常用的抗癫痫药）的口服清除率在怀孕期间会增加，其机制尚不清楚。在这项研究中，我们发现 17 β-雌二醇 (E-2) 上调 UDP 葡萄糖醛酸基转移酶 (UGT) 1A4 的表达，该酶是负责消除拉莫三嗪的主要酶。在存在 ER α 表达的情况下，E-2 处理可诱导雌激素受体 (ER) α 阴性 HepG2 细胞中 UGT1A4 内源 mRNA 表达水平增加 2.3 倍。当共转染 ER α 时，E-2 在 HepG2 细胞中以浓度依赖性方式增强 UGT1A4 的转录活性。在 ER α 阳性 MCF7 细胞中也观察到 E-2 对 UGT1A4 转录活性的诱导，通过抗雌激素氟维司群 (ICI 182,780) 预处理可消除这种活性。使用荧光素酶报告基因分析对 UGT1A4 上游区域进行分析，确定了一个推定的特异性蛋白 1 (Sp1) 结合位点（-1906 至 -1901 碱基对），该位点对于 E-2 诱导 UGT1A4 转录活性至关重要。 Sp1 结合序列的删除消除了 E-2 对 UGT1A4 的上调，并且通过电泳迁移率变动测定确定 Sp1 与假定的 Sp1 结合位点结合。使用 ER α 突变体对 ER α 结构域进行的分析表明，E-2 在 HepG2 细胞中诱导 UGT1A4 需要激活功能 (AF) 1 和 AF2 结构域，而不是 ER α 的 DNA 结合结构域。最后，E-2 处理增加了 ER α 转染的 HepG2 细胞中的拉莫三嗪葡萄糖醛酸化。总之，我们的数据表明 E-2 对 UGT1A4 表达的上调是由 ER α 和 Sp1 介导的，并且是有助于妊娠期拉莫三嗪增强消除的潜在机制。
Oral clearance of lamotrigine, an antiepileptic drug commonly used in pregnant women, is increased in pregnancy by unknown mechanisms. In this study, we show that 17 beta-estradiol (E-2) up-regulates expression of UDP glucuronosyltransferase (UGT) 1A4, the major enzyme responsible for elimination of lamotrigine. Endogenous mRNA expression levels of UGT1A4 in estrogen receptor (ER) alpha-negative HepG2 cells were induced 2.3-fold by E-2 treatment in the presence of ER alpha expression. E-2 enhanced transcriptional activity of UGT1A4 in a concentration-dependent manner in HepG2 cells when ER alpha was cotransfected. Induction of UGT1A4 transcriptional activity by E-2 was also observed in ER alpha-positive MCF7 cells, which was abrogated by pretreatment with the antiestrogen fulvestrant (ICI 182,780). Analysis of UGT1A4 upstream regions using luciferase reporter assays identified a putative specificity protein-1 (Sp1) binding site (-1906 to -1901 base pairs) that is critical for the induction of UGT1A4 transcriptional activity by E-2. Deletion of the Sp1 binding sequence abolished the UGT1A4 up-regulation by E-2, and Sp1 bound to the putative Sp1 binding site as determined by a electrophoretic mobility shift assay. Analysis of ER alpha domains using ER alpha mutants revealed that the activation function (AF) 1 and AF2 domains but not the DNA binding domain of ER alpha are required for UGT1A4 induction by E-2 in HepG2 cells. Finally, E-2 treatment increased lamotrigine glucuronidation in ER alpha-transfected HepG2 cells. Together, our data indicate that up-regulation of UGT1A4 expression by E-2 is mediated by both ER alpha and Sp1 and is a potential mechanism contributing to the enhanced elimination of lamotrigine in pregnancy.