YAP调控Notch信号通路影响小鼠NASH肝纤维化的机制及慈菇消脂方的干预作用

Mechanism of Notch signaling pathway regulated by YAP in NASH liver fibrosis mice and the intervention effect of Cigu Xiaozhi prescription

目的探讨Yes相关蛋白(YAP)调控Notch信号通路影响非酒精性脂肪性肝炎(NASH)肝纤维化的机制及解毒化痰法中药慈菇消脂方的干预作用。方法将小鼠随机分为正常组、NASH肝纤维化模型组、维替泊芬(VP)组、VP+中药低剂量组、VP+中药高剂量组和DMSO对照组。采用蛋氨酸-胆碱缺乏(MCD)饮食联合小剂量CCl4建立小鼠NASH相关肝纤维化模型,采用HE、Masson染色观察肝脏纤维化程度,ELISA法检测肝纤维化四项,碱水法测定小鼠肝脏中羟脯氨酸含量,免疫组织化学法检测α-SMA、ColⅠ、YAP、Notch1蛋白在肝脏中的定位,Western blotting及实时定量PCR检测Notch信号通路中Notch1/2、Jagged1和DLL4蛋白及mRNA表达。结果NASH肝纤维化组小鼠肝细胞肿胀、胞质透明,肝小叶、门管区以及窦周均存在明显纤维化,并伴有大量炎症细胞浸润及多量脂肪小滴,局部出现肝细胞坏死、溶解以及肝硬化;肝纤维化四项指标显著升高(P<0.01);肝细胞中α-SMA、ColⅠ、YAP以及Notch1定位于细胞质中;肝脏中YAP、Notch1/2及Jagged1均呈高表达(P<0.01)。经VP及VP联合高、低剂量中药慈菇消脂方分别干预后,小鼠肝脏中YAP、Notch1/2及Jagged1均呈低表达(P<0.05),DLL4因子在VP联合中药高剂量组上调(P<0.05)。结论YAP可能通过下调Notch1/2、Jagged1及上调DLL4,抑制Notch通路活化,干预NASH肝纤维化发生。中药慈菇消脂方通过多成分、多靶点下调YAP、Notch1/2、Jagged1、上调DLL4,抑制Notch信号通路活化,改善NASH肝纤维化进展。

Objective To investigate the regulatory mechanism of Notch signaling pathway by YAP in non-alcoholic steatohepatitis(NASH)liver fibrosis,and assess the intervention effect of Cigu Xiaozhi prescription in detoxification and phlegm treatment.Methods C57BL/6J mice were randomly divided into different groups,including a normal group,NASH liver fibrosis model group,verteporfin(VP)intervention group,VP+Chinese medicine(Cigu Xiaozhi prescription)low-dose group,VP+Chinese medicine high-dose group,and dimethyl sulfoxide control group.The methionine/choline-deficient diet combined with low-dose CCl4 was used to construct the NASH liver fibrosis model.The degree of liver fibrosis was evaluated using hematoxylin and eosin(HE)and Masson staining.Four protein factors associated with liver fibrosis were detected using enzyme-linked immunosorbent assay,and hydroxyproline levels in the mouse liver was determined using the alkaline water method.The localization ofα-SMA,ColⅠ,YAP,and Notch1 proteins in the liver was determined using immunohistochemistry.Additionally,the mRNA and protein expression levels of the Notch signaling pathway molecules,namely Notch1/2,Jagged1,and DLL4,were assessed using real-time quantitative PCR and Western blotting analyses,respectively.Results The HE and Masson staining results revealed that the liver cells of NASH liver fibrosis mice were swollen and the cytoplasm was transparent.Additionally,evident fibrosis was observed in the hepatic lobule,portal area,and sinus;it was accompanied by heightened levels of inflammatory cell infiltration,a large number of fat droplets,and instances of local hepatocyte necrosis,dissolution,and cirrhosis.The four factors associated with liver fibrosis showed a substantial increase(P<0.01).α-SMA,ColⅠ,YAP,and Notch1 were localized in the cytoplasm of hepatocytes.YAP,Notch1/2,and Jagged1 were highly expressed in the liver(P<0.01)but were downregulated after intervention with VP and VP+high and low doses of Cigu Xiaozhi prescription(P<0.05).Meanwhile,DLL4 factor was upregulated in the VP+high-dose of Cigu Xiaozhi prescription group(P<0.05).Conclusion YAP may inhibit activation of the Notch pathway by downregulating Notch1/2 and Jagged1 and upregulating DLL4,thereby interfering with the occurrence of liver fibrosis in NASH.Treatment with Cigu Xiaozhi prescription may inhibit Notch signaling pathway activation by downregulating YAP,Notch1/2,and Jagged1 and upregulating DLL4 through its multi-components and multi-targets properties,ultimately slow the progression of liver fibrosis in NASH.