肝纤维化中丹参素对TGFβ1/Smads/ERK信号通路的影响及其相互关系

目的探讨肝纤维化过程中转化生长因子β1(transforming growth factorβ,TGFβ1)/Smads/细胞外信号调节激酶(extracellular signal-regulated kinase,ERK)通路的相互作用。方法体外分离培养大鼠肝星状细胞(hepatic stellatecell,HSC),MTT法筛选丹参素最适浓度;以最适浓度丹参素及ERK阻断剂(PD98059)作用于经TGFβ1处理的HSC,CCK-8法检测各组HSC增殖;免疫细胞化学染色法检测各组HSC内α-平滑肌肌动蛋白(α-smooth muscle sctin,α-SMA)及Ⅰ、Ⅲ型胶原表达;RT-PCR检测各组HSC的Smad2、Smad3、Smad7 mRNA表达量;Western blot法检测各组Smad2/3、ERK1/2蛋白磷酸化及Smad7蛋白水平。结果 0.062 5～0.25 mmol/L的丹参素可有效抑制HSC增殖,作为最适处理浓度;PD98059(100μmol/L)可抑制TGFβ1诱导的HSC增殖,丹参素剂量依赖性抑制TGFβ1诱导的HSC增殖(P<0.01);TGFβ1促进细胞内α-SMA及Ⅰ、Ⅲ型胶原表达,PD98059及丹参素降低TGFβ1诱导的α-SMA及Ⅰ、Ⅲ型胶原水平;PD98059可拮抗TGFβ1诱导的Smad2、Smad3、Smad7 mRNA的表达(P<0.05,P<0.01),丹参素下调Smad2、Smad3 mRNA水平,但上调Smad7 mRNA水平(P<0.01);PD98059及丹参素抑制TGFβ1诱导的Smad2/3、ERK1/2蛋白磷酸化(P<0.01),但对TGFβ1诱导的Smad7蛋白表达上调有不同效应(P<0.01)。结论 TGFβ1上调Smad2、Smad3 mRNA表达及蛋白磷酸化,进而诱导HSC增殖、活化及胶原合成,ERK通路可能参与HSC中TGFβ1诱导Smad基因表达及蛋白磷酸化过程。丹参素对TGFβ1/Smad/ERK信号通路具有抑制效应。

Tanshinol inhibits TGF1/Smads/ERK signaling pathways in rat hepatic stellate cells

Objective To investigate the interactions of transforming growth factor β1(TGFβ1)/Smads/extracellular signal-regulated kinase(ERK) signaling pathways in hepatic fibrosis and the anti-fibrotic molecular mechanism of Tanshinol in those processes.Methods Rat hepatic stellate cells(HSCs) were primarily isolated by in situ liver recirculation and then cultured.MTT colorimetric assay was used to determine the optimal concentration of Tanshinol.HSCs were divided into 3 groups,TGFβ1 treatment group(5 ng/ml),TGFβ1+ ERK blocking agent(PD98059,100 μmol/L) treatment group,and TGFβ1+Tanshinol treatment groups.The proliferation of HSC in each groups was measured by Cell Counting Kit-8(CCK-8).The protein expressions of α-smooth muscle actin(α-SMA),and collagen Ⅰ,Ⅲ were detected by immunocytochemical staining.The mRNA expressions of Smad2,3 and 7 in the HSCs were detected by RT-PCR.The phosphorylation levels of Smad2/3 and ERK1/2 proteins and Smad7 protein were detected by Western blotting.Results At the treatment of Tanshinol at concentrations of 0.0625,0.125 and 0.25 mmol/L,the proliferation of HSC was significantly inhibited.PD98059(100 μmol/L) inhibited the HSC proliferation induced by TGFβ1,and Tanshinol inhibited the TGFβ1-induced HSCs proliferation in a dose-dependent manner(P<0.01).TGFβ1 enhanced the expression levels of α-SMA,and collagen Ⅰ and Ⅲ in HSCs(P<0.01).PD98059 and Tanshinol decreased these expressions(P<0.01).PD98059 depressed the mRNA levels of Smad2,3 and 7 induced by TGFβ1(P<0.01,0.05).However,Tanshinol only down-regulated the mRNA levels of Smad2 and 3,but up-regulated that of Smad7(P<0.01).PD98059 and Tanshinol decreased the contents of phosphorylated Smad2/3 and ERK1/2 proteins(P<0.01),while they had different effects on the expression of Smad7 protein(P<0.01).Conclusion TGFβ1 up-regulates the expressions of Smad2 and 3 mRNA,and phosphorylated proteines to induce the proliferation,activation,and collagen synthesis of HSCs.ERK signaling pathway might be involved in TGFβ1-induced Smad mRNA expression and protein phosphorylation.Tanshinol inhibits the signaling pathways of TGFβ/Smad/ERK in hepatic fibrosis.