State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China.
State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China.
J Proteomics. 2018 Apr 15;177:40-47. doi: 10.1016/j.jprot.2018.02.014. Epub 2018 Feb 10.
Polygoni Multiflori Radix (PMR) has been commonly used as a tonic in China for centuries. However, PMR-associated hepatotoxicity is becoming a safety issue. Cholestasis often occurs in PMR-induced hepatotoxicity in clinical medicine, but the exact mechanism is not completely understood. An RNA-Seq method was employed, in the present study, to explore the molecular mechanism of cholestatic liver injury induced by PMR, characterized by the hepatic transcriptional response in rats exposed to 1 and 20 g/kg PMR for 90 days. Pathological changes seen in rat livers exposed to PMR included increased bile ducts in portal areas and biliary epithelial cell hyperplasia, which were accompanied by the elevation of serum biochemistries. Dose-dependent increases in the expression of 14 transcripts encoding enzymes involved in the cholesterol biosynthetic pathway were identified. Furthermore, cholesterol 7-alpha hydroxylase (Cyp7a1), a rate-limiting enzyme in the synthesis of bile acids (BAs) from cholesterol, was found to be upregulated by PMR treatment. Protein analysis by western blot suggested that expression of 3-hydroxy-3-methylglutaryl CoA reductase (Hmgcr) and Cyp7a1 were increased in a dose-dependent manner. Collectively, the present study demonstrates that PMR upregulates key enzymes for biosynthesis of cholesterol and BA, which poses the risk of cholestatic liver injury.
To the best of our knowledge, this is the first transcriptome analysis to highlight the main molecular changes occurring in rats chronic exposed to PMR. We have identified 39 specific differentially expressed genes (DEGs) that were present in various comparisons. A total of 14 of these altered gene transcripts were associated with cholesterol biosynthesis. Another factor of great importance in our opinion seemed to be the enhancement of bile acid (BA) biosynthesis, which were closely linked to cholesterol biosynthesis or metabolism. Our findings suggested that the disturbance on balance of BA formation and elimination might lead to a BA overload in hepatocytes, thereby resulting in liver injury.
千百年来，何首乌（PMR）一直被用作中国的滋补品。然而，PMR 相关的肝毒性正成为一个安全问题。在临床医学中，PMR 诱导的肝毒性常伴有胆汁淤积，但确切的机制尚不完全清楚。本研究采用 RNA-Seq 方法，探讨 PMR 诱导的胆汁淤积性肝损伤的分子机制，即暴露于 1 和 20g/kg PMR 90 天的大鼠肝组织的转录组反应。PMR 暴露大鼠肝脏的组织学变化包括门脉区胆管增多和胆管上皮细胞增生，同时伴有血清生化指标升高。确定了 14 种编码胆固醇生物合成途径相关酶的转录本表达呈剂量依赖性增加。此外，胆固醇 7-α羟化酶（Cyp7a1），胆固醇合成胆汁酸（BAs）的限速酶，被发现被 PMR 处理上调。Western blot 蛋白分析表明，3-羟-3-甲基戊二酰辅酶 A 还原酶（Hmgcr）和 Cyp7a1 的表达呈剂量依赖性增加。综上所述，本研究表明 PMR 上调了胆固醇和 BA 生物合成的关键酶，这增加了胆汁淤积性肝损伤的风险。
据我们所知，这是第一篇强调大鼠慢性暴露于 PMR 时发生的主要分子变化的转录组分析。我们在各种比较中鉴定了 39 个存在的特异性差异表达基因（DEGs）。其中 14 个改变的基因转录本与胆固醇生物合成有关。另一个在我们看来非常重要的因素似乎是增强了胆汁酸（BA）的生物合成，这与胆固醇生物合成或代谢密切相关。我们的研究结果表明，BA 形成和消除的平衡失调可能导致肝细胞内 BA 过载，从而导致肝损伤。
