肌细胞增强因子2A与肝星状细胞活化关系的体内实验研究

In vivo Study of Relationship between Myocyte Enhancer Factor 2A and Activation of Hepatic Stellate Cells

背景:转录调控在肝星状细胞(HSC)活化过程中起重要作用,研究显示转录因子肌细胞增强因子2(MEF2)参与了HSC的活化过程。目的:探讨肝纤维化形成过程中MEF2家族成员MEF2A与HSC活化的关系。方法:实验开始时处死6只大鼠作为0周对照组,64只大鼠随机分为正常对照组和肝纤维化模型组。模型组大鼠皮下注射60%CCl_4(0.3 ml/100 g,每周2次)复制肝纤维化模型;正常对照组大鼠与模型组于相同条件下饲养,不予任何处理。造模开始后3、6、9、12周分批处死大鼠,取肝组织,实时荧光定量聚合酶链反应(PCR)检测MEF2A mRNA表达,蛋白质印迹法检测MEF2A蛋白和HSC活化标记物α-平滑肌肌动蛋白(α-SMA)表达,Van Gieson染色定量分析肝内胶原含量。结果:正常肝组织中仅有少量MEF2A mRNA和蛋白表达;随着肝纤维化的形成,肝组织MEF2A mRNA和蛋白表达量逐渐增加(P<0.05),MEF2A与α-SMA蛋白表达呈正相关(r=0.88,P<0.05)。肝内胶原含量随肝纤维化的形成呈递增趋势(P<0.01)。结论:MEF2A参与了CCl_4诱导的大鼠肝纤维化形成过程中HSC的活化和增殖。

Background： Transcriptional regulation plays a key role in the activation of hepatic stellate cells （HSC）. It has been demonstrated that transcriptional factor myocyte enhancer factor 2 （MEF2） is implicated in the activation of HSC. Aims： To investigate the relationship between MEF2A, a member of MEF2 family, and HSC activation in hepatic fibrogenesis. Methods： Six rats were sacrificed prior to the experiment as 0 week controls. The other 64 rats were randomly divided into normal control group and fibrotic model group. Rats in the model group were injected with 60% CCl4 subcutaneously twice a week at a dosage of 0.3 ml/100 g, while rats in the normal control group were raised without any intervention. The rats were sacrificed 3, 6, 9 and 12 weeks after starting of CCl4 administration in batch to collect the liver specimens. Expression of MEF2A mRNA was determined by real-time fluorescent quantitative polymerase chain reaction （PCR）; and protein expressions of MEF2A and α-smooth muscle aetin （α-SMA, the marker of HSC activation） were determined by Western blotting. Contents of hepatic collagen were assayed quantitatively by Van Gieson＇s staining. Results： MEF2A mRNA and protein were only weakly expressed in normal liver tissues, and increased gradually in parallel with hepatic fibrogenesis （P〈0.05）. Protein expression of MEF2A was positively correlated with that of α-SMA （r=0.88, P〈0.05）. Contents of hepatic collagen showed an increasing tendency with hepatic fibrogenesis （P〈0.01）. Conclusions： MEF2A is involved in the activation and proliferation of HSC in CCl4-induced liver fibrosis in rats.