Clinical Pharmacology Institute, Pharmaceutical School, Nanchang University, Nanchang 330031, P. R. China; Department of Pharmacy, The First Affiliated Hospital of Nanchang University, Nanchang 330006, P. R. China.
Clinical Pharmacology Institute, Pharmaceutical School, Nanchang University, Nanchang 330031, P. R. China.
Phytomedicine. 2023 Jan;108:154529. doi: 10.1016/j.phymed.2022.154529. Epub 2022 Oct 28.
Previous studies have shown that the anti-cholestatic effect of oleanolic acid (OA) is associated with FXR and NRF2. However, how the two signaling pathways cooperate to regulate the anti-cholestatic effect of OA remains unclear.
This study aimed to further demonstrate the effect of OA on alpha-naphthyl isothiocyanate (ANIT)-induced cholestatic liver injury and the interaction mechanism between NRF2 and FXR signaling pathways in maintaining bile acid homeostasis.
Gene knockout animals and cell models, metabolomics analysis, and co-immunoprecipitation were used to investigate the mechanism of OA against cholestatic liver injury.
The effect of OA against ANIT-induced liver injury in rats was dramatically reduced after Nrf2 gene knockdown. With the silencing of Fxr, the hepatoprotective effect of OA was weakened, but it still effectively alleviated cholestatic liver injury in rats. In L02 cells, OA can up-regulate the levels of NRF2, FXR, BSEP and UGT1A1, and reduce the expression of CYP7A1. Silencing of NRF2 or FXR significantly attenuated the protective effect of OA on ANIT-induced L02 cell injury and its regulation on downstream target genes, and the influence of NRF2 gene silencing on OA appeared to be greater. The NRF2 activator sulforaphane, and the FXR activator GW4064 both remarkably promoted NRF2 binding to P300 and FXR to RXRα, but reduced β-catenin binding to P300 and β-catenin binding to FXR.
The effect of OA on cholestatic liver injury is closely related to the simultaneous activation of NRF2 and FXR dual signaling pathways, in which NRF2 signaling pathway plays a more important role. The dual signaling pathways of NRF2 and FXR cooperatively regulate bile acid metabolic homeostasis through the interaction mechanism with β-catenin/P300.
先前的研究表明，齐墩果酸（OA）的抗胆汁淤积作用与 FXR 和 NRF2 有关。然而，这两条信号通路如何协同调节 OA 的抗胆汁淤积作用尚不清楚。
本研究旨在进一步证明 OA 对α-萘基异硫氰酸酯（ANIT）诱导的胆汁淤积性肝损伤的作用，以及 NRF2 和 FXR 信号通路在维持胆汁酸动态平衡中的相互作用机制。
采用基因敲除动物和细胞模型、代谢组学分析和共免疫沉淀法来研究 OA 对抗胆汁淤积性肝损伤的作用机制。
在 Nrf2 基因敲低后，OA 对 ANIT 诱导的大鼠肝损伤的作用明显减弱。沉默 Fxr 后，OA 的肝保护作用减弱，但仍能有效缓解大鼠胆汁淤积性肝损伤。在 L02 细胞中，OA 可上调 NRF2、FXR、BSEP 和 UGT1A1 的水平，降低 CYP7A1 的表达。沉默 NRF2 或 FXR 显著减弱了 OA 对 ANIT 诱导的 L02 细胞损伤及其对下游靶基因的调节作用，且 NRF2 基因沉默对 OA 的影响似乎更大。NRF2 激活剂萝卜硫素和 FXR 激活剂 GW4064 均显著促进 NRF2 与 P300 结合以及 FXR 与 RXRα 结合，但减少了β-catenin 与 P300 结合以及β-catenin 与 FXR 结合。
OA 对胆汁淤积性肝损伤的作用与 NRF2 和 FXR 双信号通路的同时激活密切相关，其中 NRF2 信号通路发挥更重要的作用。NRF2 和 FXR 双信号通路通过与β-catenin/P300 的相互作用机制，共同调节胆汁酸代谢的动态平衡。
