Interleukin-18 Down-Regulates Multidrug Resistance-Associated Protein 2 Expression through Farnesoid X Receptor Associated with Nuclear Factor Kappa B and Yin Yang 1 in Human Hepatoma HepG2 Cells.
Interleukin-18 Down-Regulates Multidrug Resistance-Associated Protein 2 Expression through Farnesoid X Receptor Associated with Nuclear Factor Kappa B and Yin Yang 1 in Human Hepatoma HepG2 Cells.
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Interleukin-18 通过与核因子 Kappa B 和 Yin Yang 1 相关的 Farnesoid X 受体下调人肝癌 HepG2 细胞中多药耐药相关蛋白 2 的表达
DOI：
10.1371/journal.pone.0136215
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Chen WS
中科院分区：
文献类型：
--
作者：
Liu XC;Lian W;Zhang LJ;Feng XC;Gao Y;Li SX;Liu C;Cheng Y;Yang L;Wang XJ;Chen L;Wang RQ;Chai J;Chen WS
多药耐药相关蛋白2(MRP2)通过转运有机阴离子结合物，包括结合胆红素、谷胱甘肽、硫酸盐和多种药物，在胆汁酸代谢中发挥重要作用。在胆汁淤积症患者和啮齿动物中，MRP2的表达降低。然而，MRP2下调的分子机制仍然不清楚。本研究用白细胞介素18(IL-18)处理人肝癌细胞，用实时定量聚合酶链式反应和免疫印迹法检测MRP2、核因子-κB、法尼醇X受体和转录因子阴阳1的表达。我们发现，IL-18对MRP2的表达在mRNA和蛋白水平均有抑制作用，且呈剂量和时间依赖关系。此外，激活的NF-κB通路增加了YY1，降低了FXR。随着NF-κB亚单位p65的下调，这些变化在HepG2细胞中都有所减弱。YY1基因敲除后，IL-18诱导的Hep G2细胞中FXR和MRP2表达的降低也被减弱。我们进一步观察到，在胆管结扎的SD大鼠肝脏中，IL-18、NF-κB和YY1的表达显著升高，而FXR和MRP2的表达显著降低。染色质免疫沉淀分析还表明，与MRP2启动子区域结合的FXR在胆管结扎大鼠的肝脏提取液中的含量低于假手术大鼠。我们的研究结果表明，IL-18通过核受体FxR下调肝癌细胞中MRP2的表达，可能是通过核转录因子κB和YY1介导的。
Multidrug resistance-associated protein 2 (MRP2) plays an important role in bile acid metabolism by transporting toxic organic anion conjugates, including conjugated bilirubin, glutathione, sulfate, and multifarious drugs. MRP2 expression is reduced in cholestatic patients and rodents. However, the molecular mechanism of MRP2 down-regulation remains elusive. In this report, we treated human hepatoma HepG2 cells with interleukin-18 (IL-18) and measured the expression of MRP2, nuclear factor kappa B (NF-κB), farnesoid X receptor (FXR), and the transcription factor Yin Yang 1 (YY1) by quantitative real-time quantitative polymerase chain reaction (PCR) and western blotting. We found that expression of MRP2 was repressed by IL-18 at both the mRNA and protein levels in a dose- and time-dependent manner. Furthermore, the activated NF-κB pathway increased YY1 and reduced FXR. These changes were all attenuated in HepG2 cells with knockdown of the NF-κB subunit, p65. The reduced expression of FXR and MRP2 in HepG2 cells that had been caused by IL-18 treatment was also attenuated by YY1 knockdown. We further observed significantly elevated IL-18, NF-κB, and YY1 expression and decreased FXR and MRP2 expression in bile duct-ligated Sprague Dawley rat livers. Chromatin immunoprecipitation assays also showed that FXR bound to the promoter region in MRP2 was less abundant in liver extracts from bile duct-ligated rats than sham-operated rats. Our findings indicate that IL-18 down-regulates MRP2 expression through the nuclear receptor FXR in HepG2 cells, and may be mediated by NF-κB and YY1.