Interleukin-1β represses MRP2 gene expression through inactivation of interferon regulatory factor 3 in HepG2 cells
Interleukin-1β represses MRP2 gene expression through inactivation of interferon regulatory factor 3 in HepG2 cells
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DOI：
10.1002/hep.20216
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发表时间：
2004-06-01
期刊：
影响因子：
13.5
通讯作者：
Uchiumi, T
中科院分区：
文献类型：
--
作者：
Hisaeda, K;Inokuchi, A;Uchiumi, T
人多药耐药蛋白2（MRP 2/ABCC 2），表达于胆小管膜上，介导多种有机阴离子的多特异性外排，包括葡萄糖醛酸盐、硫酸盐和谷胱甘肽的缀合物。MRP 2的表达可以响应于环境刺激如胆汁淤积和黄疸而改变。我们以前报道过，MRP 2 mRNA表达水平在丙型肝炎病毒感染的人肝组织的非肿瘤部分降低，并且炎性细胞因子抑制MRP 2在人肝细胞（HepG 2）中的表达。我们研究了炎症细胞因子调节肝细胞MRP 2基因表达的分子机制。用白细胞介素-1 β（IL-1 β）或肿瘤坏死因子a处理人肝细胞导致MRP 2的蛋白和mRNA水平降低。IL-1 β抑制MRP 2启动子构建体的转录活性达40%，这种MRP 2启动子活性的抑制是通过干扰素刺激反应元件（ISRE）介导的。用IL-1 β处理的核提取物进行的电泳迁移率变化分析显示DNA蛋白复合物的形成减少，特别是那些包括干扰素调节因子3（IRF 3）的复合物。重组人IRF 3的表达增加了MRP 2启动子的活性。用特异性细胞外信号调节激酶抑制剂治疗减轻了IL-1 β诱导的MRP 2 mRNA下调，并消除了IRF 3与ISRE元件的结合。总之，IL-1 β通过使IRF 3与人肝细胞中MRP 2启动子上的ISRE结合失活来诱导MRP 2基因的下调;这种失活是通过干扰细胞外信号调节激酶途径来实现的。
The human multidrug resistance protein 2 (MRP2/ABCC2), expressed on the bile canalicular membrane, mediates the multispecific efflux of several organic anions, including conjugates of glucuronate, sulfate, and glutathione. Expression of MRP2 can be altered in response to environmental stimuli such as cholestasis and jaundice. We previously reported that MRP2 mRNA expression levels are decreased in the nontumorous part of hepatitis C virus-infected human liver tissues, and that inflammatory cytokines inhibit MRP2 expression in human hepatic (HepG2) cells. We investigated the molecular mechanisms by which inflammatory cytokines modulate MRP2 gene expression in hepatic cells. Treatment of human hepatic cells with interleukin-1beta (IL-1beta) or tumor necrosis factor a resulted in a decrease in the protein and mRNA levels of MRP2. IL-1beta inhibited the transcriptional activity of MRP2 promoter constructs by 40%, and this inhibition of MRP2 promoter activity was mediated through the interferon stimulatory response element (ISRE). Electrophoretic mobility shift assays with IL-1beta-treated nuclear extracts showed a decrease in the formation of DNA protein complexes, specifically those including interferon regulatory factor 3 (IRF3). Expression of recombinant human IRF3 increased MRP2 promoter activity. Treatment with a specific extracellular signal-regulated kinase inhibitor relieved IL-1beta-induced MRP2 mRNA downregulation and abrogated the binding of IRF3 to the ISRE element. In conclusion, IL-1beta induces downregulation of the MRP2 gene by inactivating IRF3 binding to ISRE on the MRP2 promoter in human hepatic cells; this inactivation is accomplished via interference with the extracellular signal-regulated kinase pathway.