Metabolism and Toxicity of Emodin: Genome-Wide Association Studies Reveal Hepatocyte Nuclear Factor 4α Regulates UGT2B7 and Emodin Glucuronidation
Metabolism and Toxicity of Emodin: Genome-Wide Association Studies Reveal Hepatocyte Nuclear Factor 4α Regulates UGT2B7 and Emodin Glucuronidation
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大黄素的代谢和毒性：全基因组关联研究揭示肝细胞核因子 4 α 调节 UGT2B7 和大黄素葡萄糖醛酸化
DOI：
10.1021/acs.chemrestox.0c00047
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发表时间：
2020-07-20
影响因子：
4.1
通讯作者：
Tang, Lan
中科院分区：
文献类型：
--
作者：
Chen, Yulian;Zhang, Tao;Tang, Lan
大黄素是大黄等中药材的主要有毒成分。我们之前的研究表明，udp -葡萄糖醛酸糖基转移酶2B7 （UGT2B7）的遗传多态性与大黄素的糖醛酸化和解毒有关。本研究旨在揭示UGT2B7对大黄素糖醛酸化的转录调控机制及其毒性作用。从36个临床人肾组织中获得大黄素葡萄糖醛酸活性、基因组和转录组数据。全基因组关联研究（GWAS）发现，位于肝细胞核因子4 α (HNF4A)基因上的4个单核苷酸多态性（rs6093966、rs2868094、rs2071197和rs6073433）与大黄素糖醛酸化显著相关（p < 0.05）。值得注意的是，rs2071197与HNF4A和UGT2B7基因表达及大黄素糖醛酸化显著相关。HNF4A基因表达与UGT2B7呈高度相关（R-2 = 0.721, p = 5.83 × 10(-11)）。293T细胞荧光素酶活性增加7.68倍，HepG2细胞荧光素酶活性增加2.03倍，证实了HNF4A对UGT2B7启动子的显著转录激活。HNF4A在HepG2细胞中的表达下调（36.6%）导致UGT2B7显著降低（19.8%），细胞毒性升高（p < 0.05）。HNF4A在HepG2细胞中过表达（31.2%），导致UGT2B7显著升高（24.4%），细胞活力提高（p < 0.05）。此外，大黄素处理后HepG2细胞和大鼠的HNF4A和UGT2B7均降低。综上所述，长期或大剂量使用大黄素可抑制HNF4A的表达，从而降低UGT2B7的表达，引起肝毒性。
Emodin is the main toxic component in Chinese medicinal herbs such as rhubarb. Our previous studies demonstrated that genetic polymorphisms of UDP-glucuronosyltransferase 2B7 (UGT2B7) had an effect on the glucuronidation and detoxification of emodin. This study aimed to reveal the transcriptional regulation mechanism of UGT2B7 on emodin glucuronidation and its effect on toxicity. Emodin glucuronic activity and genome and transcriptome data were obtained from 36 clinical human kidney tissues. The genome-wide association studies (GWAS) identified that four single nucleotide polymorphisms (SNPs) (rs6093966, rs2868094, rs2071197, and rs6073433), which were located on the hepatocyte nuclear factor 4 alpha (HNF4A) gene, were significantly associated with the emodin glucuronidation (p < 0.05). Notably, rs2071197 was significantly associated with the gene expression of HNF4A and UGT2B7 and the glucuronidation of emodin. The gene expression of HNF4A showed a high correlation with UGT2B7 (R-2 = 0.721, p = 5.83 x 10(-11)). The luciferase activity was increased 7.68-fold in 293T cells and 2.03-fold in HepG2 cells, confirming a significant transcriptional activation of UGT2B7 promoter by HNF4A. The knockdown of HNF4A in HepG2 cells (36.6%) led to a significant decrease of UGT2B7 (19.8%) and higher cytotoxicity (p < 0.05). The overexpression of HNF4A in HepG2 cells (31.2%) led to a significant increase of UGT2B7 (24.4%) and improved cell viability (p < 0.05). Besides, HNF4A and UGT2B7 were both decreased in HepG2 cells and rats after treatment with emodin. In conclusion, emodin used long term or in high doses could inhibit the expression of HNF4A, thereby reducing the expression of UGT2B7 and causing hepatotoxicity.