Jiangsu Key Laboratory for Pharmacology and Safety Evaluation of Chinese Materia Medica, School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, China.
The Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, China.
Br J Pharmacol. 2021 Jun;178(11):2246-2265. doi: 10.1111/bph.15289. Epub 2021 Apr 14.
Portal hypertension is a lethal complication of cirrhosis. Its mechanism and therapeutic targets remain largely unknown. Hepatic stellate cell (HSC) contraction increases intrahepatic vascular resistance contributing to portal hypertension. We investigated how HSC contraction was regulated by Wnt signalling and the therapeutic implications.
Liver tissues from cirrhotic patients were examined. Cirrhotic mice with genetic or pharmacological treatments were used for in vivo assessments, and their primary cells were isolated. Cellular functions and signalling pathways were analysed in human HSC-LX2 cells using real-time PCR, Western blotting, siRNA, luciferase reporter assay, chromatin immunoprecipitation, co-immunoprecipitation and site-directed mutagenesis.
Wnt/β-catenin correlated with HSC contraction in human cirrhotic liver. Wnt3a stimulated Smo-independent Gli1 nuclear translocation followed by LARG-mediated RhoA activation leading to HSC contraction. Suppressor of fused (Sufu) negatively mediated Wnt3a-induced Gli1 nuclear translocation. Wnt/β-catenin repressed transcription of Sufu dependent on β-catenin/TCF4 interaction and TCF4 binding to Sufu promoter. Molecular simulation and site-directed mutagenesis identified the β-catenin residues Lys312 and Lys435 critically involved in this interaction. TCF4 binding to the sequence CACACCTTCC at Sufu promoter was required for transrepression of Sufu. In cirrhotic mice, short-term liver-targeting β-catenin deficiency or acute treatment with β-catenin inhibitors reduced portal pressure via restriction of HSC contraction rather than inhibiting HSC activation. Long-term deficiency or treatments also ameliorated liver injury, fibrosis and inflammation.
Interaction between Wnt/β-catenin and Smo-independent Gli1 pathways promoted HSC contraction via TCF4-dependent transrepression of Sufu. HSC-specific inhibition of β-catenin may have therapeutic benefits for cirrhotic portal hypertension.
门脉高压是肝硬化的致命并发症。其发病机制和治疗靶点在很大程度上仍不清楚。肝星状细胞（HSC）收缩增加肝内血管阻力，导致门脉高压。我们研究了 Wnt 信号如何调节 HSC 收缩及其治疗意义。
检测肝硬化患者的肝组织。使用基因或药物治疗的肝硬化小鼠进行体内评估，并分离其原代细胞。使用实时 PCR、Western blot、siRNA、荧光素酶报告基因检测、染色质免疫沉淀、共免疫沉淀和定点突变等方法分析人 HSC-LX2 细胞中的细胞功能和信号通路。
Wnt/β-catenin 与人类肝硬化肝组织中的 HSC 收缩相关。Wnt3a 刺激 Smo 非依赖性 Gli1 核易位，随后 LARG 介导 RhoA 激活导致 HSC 收缩。Sufu 抑制融合蛋白（Sufu）负调控 Wnt3a 诱导的 Gli1 核易位。Wnt/β-catenin 依赖于 β-catenin/TCF4 相互作用和 TCF4 结合到 Sufu 启动子抑制 Sufu 的转录。分子模拟和定点突变确定了β-catenin 残基 Lys312 和 Lys435 在此相互作用中起关键作用。TCF4 结合到 Sufu 启动子上的序列 CACACCTTCC 对于 Sufu 的转录抑制是必需的。在肝硬化小鼠中，短期肝靶向β-catenin 缺乏或急性使用β-catenin 抑制剂通过限制 HSC 收缩而不是抑制 HSC 激活来降低门脉压。长期缺乏或治疗也改善了肝损伤、纤维化和炎症。
Wnt/β-catenin 与 Smo 非依赖性 Gli1 通路之间的相互作用通过 TCF4 依赖性 Sufu 转录抑制促进 HSC 收缩。HSC 特异性抑制β-catenin 可能对肝硬化门脉高压具有治疗益处。
