State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China.
State Key Laboratory Cultivation Base for TCM Quality and Efficacy, Nanjing University of Chinese Medicine, Nanjing, China.
Br J Pharmacol. 2019 Jun;176(11):1619-1634. doi: 10.1111/bph.14573. Epub 2019 Apr 24.
Excessive fructose consumption is a risk factor for liver fibrosis. Pterostilbene protects against liver fibrosis. Here, we investigated the potential role and the mechanisms underlying the hepatocyte epithelial-mesenchymal transition (EMT) in fructose-induced liver fibrosis and protection by pterostilbene.
Characteristic features of liver fibrosis in 10% fructose-fed rats and EMT in 5 mM fructose-exposed BRL-3A cells with or without pterostilbene and the change of miR-34a/Sirt1/p53 and transforming growth factor-β1 (TGF-β1)/Smads signalling were examined. MiR-34a inhibitor, miR-34a minic, or p53 siRNA were used to explore the role of miR-34a/Sirt1/p53 signalling in fructose-induced EMT and the action of pterostilbene.
Pterostilbene prevented fructose-induced liver injury with fibrosis in rats. Fructose caused hepatocyte undergoing EMT, gaining fibroblast-specific protein 1 and vimentin, and losing E-cadherin, effects attenuated by pterostilbene. Moreover, fructose induced miR-34a overexpression in hepatocytes with down-regulated Sirt1, increased p53 and ac-p53, and activated TGF-β1/Smads signalling, whereas these disturbances were suppressed by miR-34a inhibitor. Additionally, miR-34a inhibitor and p53 siRNA prevented TGF-β1-driven hepatocyte EMT under fructose exposure. Pterostilbene down-regulated miR-34a, up-regulated Sirt1, and suppressed p53 activation and TGF-β1/Smads signalling in fructose-stimulated animals and cells but showed no additional effects with miR-34a inhibitor on miR-34a/Sirt1/p53 signalling in fructose-exposed hepatocytes.
These results strongly suggest that activation of miR-34a/Sirt1/p53 signalling is required for fructose-induced hepatocyte EMT mediated by TGF-β1/Smads signalling, contributing to liver fibrosis in rats. Pterostilbene exhibits a protective effect against liver fibrosis at least partly through inhibiting miR-34a/Sirt1/p53 signalling activation.
过量摄入果糖是肝纤维化的一个风险因素。紫檀芪可预防肝纤维化。在此，我们研究了果糖诱导的肝纤维化中肝细胞上皮-间充质转化（EMT）的潜在作用和机制，以及紫檀芪的保护作用。
在 10%果糖喂养的大鼠中观察肝纤维化的特征，在 5mM 果糖暴露的 BRL-3A 细胞中观察 EMT 以及紫檀芪和 miR-34a/Sirt1/p53 及转化生长因子-β1（TGF-β1）/Smads 信号的变化。使用 miR-34a 抑制剂、miR-34a 模拟物或 p53 siRNA 探讨 miR-34a/Sirt1/p53 信号在果糖诱导的 EMT 中的作用以及紫檀芪的作用。
紫檀芪可预防大鼠果糖诱导的肝损伤伴纤维化。果糖导致肝细胞发生 EMT，获得成纤维细胞特异性蛋白 1 和波形蛋白，失去 E-钙黏蛋白，这些作用可被紫檀芪减弱。此外，果糖诱导肝细胞中 miR-34a 过表达，同时下调 Sirt1，增加 p53 和 ac-p53，激活 TGF-β1/Smads 信号，而这些干扰可被 miR-34a 抑制剂抑制。此外，miR-34a 抑制剂和 p53 siRNA 可阻止果糖暴露下 TGF-β1 驱动的肝细胞 EMT。紫檀芪在果糖刺激的动物和细胞中下调 miR-34a，上调 Sirt1，并抑制 p53 激活和 TGF-β1/Smads 信号，但在果糖暴露的肝细胞中 miR-34a 抑制剂对 miR-34a/Sirt1/p53 信号无额外作用。
这些结果强烈表明，miR-34a/Sirt1/p53 信号的激活是果糖诱导的 TGF-β1/Smads 信号介导的肝细胞 EMT 所必需的，导致大鼠肝纤维化。紫檀芪对肝纤维化具有保护作用，至少部分是通过抑制 miR-34a/Sirt1/p53 信号的激活。
