中文摘要：

血管紧张素Ⅱ（AngⅡ）可诱导其前体基因在血管平滑肌细胞（vascular smooth muscle cells, VSMC）中进行表达，其作用机制与促进转录激活蛋白-1（activating protein-1，AP-1）的基因调控区中存在的AP-1位点结合有关．为进一步明确AngⅡ调节AP-1结合活性的分子机制，用放线菌酮（cycloheximide，CHX）作为c-Jun磷酸化抑制剂，经DNA-蛋白质相互作用和蛋白质印迹实验，探讨AngⅡ对AP-1结合活性的影响并探讨其分子机制．结果表明，受AngⅡ刺激的VSMG，其核蛋白中AP-1的组成亚基之一c-Jun水平明显升高．免疫细胞化学染色显示，在被AngⅡ处理的细胞中，c-Jun主要定位于细胞核，胞浆中几乎检测不出该转录激活蛋白的存在．用丝氨酸磷酸化抗体检测证实，AngⅡ可诱导c-Jun磷酸化．电泳迁移率改变分析（electrophoretic mobility shift assay, EMSA）显示，c-Jun的磷酸化水平与AP-1结合血管紧张素原基因顺式元件的活性，和对该基因的转录激活作用呈正相关关系，CHX通过阻断c-Jun磷酸化抑制AngⅡ诱导的AP-1结合活性，但是不影响c-Jun的表达水平．上述结果提示，AP-1的磷酸化活化是AngⅡ正反馈调节其前体基因表达的重要机制之一，首次发现CHX是c-Jun磷酸化的抑制剂．

英文摘要：

Angiotensin Ⅱ （Ang Ⅱ ） can induce the expression of its precursor, angiotensinogen, in vascular smooth muscle cells （VSMC）, which is related with increased activating protein-1 （AP-1） binding to its cis-element located in the angiotensinogen gene promoter. In the present study, cycloheximide （CHX） was used as an inhibitor to interrupt c-Jun, the role of AP-1 in Ang Ⅱ -induced its precursor gene activation was investigated by DNA-protein interaction and immunoblotting. The results showed that the level of c-Jun, the component of transcription factor AP-1, was significantly increased in the nucleus of VSMC after Ang Ⅱ treatment. The majority of c-Jun was found in the nucleus but hardly detected in the cytoplasm by immunocytochemistry staining. Immunoprecipitation assays confirmed that Ang Ⅱ could induce serine phosphorylation of c-Jun. EMSA results indicated that the level of phosphorylated of c-Jun had a positive correlation with AP-1 binding activity to cis-acting element of angiotensinogen gene and transcription activation of angiotensinogen. CHX inhibited Ang Ⅱ - induced binding activity of AP-1 by reducing the phosphorylation of c-Jun, though it did not affect the expression of c-Jun. These findings suggest that the AP-1 phosphorylation induced by Ang Ⅱ is one of the important mechanisms whereby Ang Ⅱ regulates its precursor gene expression in feedback manner. It is found that CHX is an inhibitor to phosphorylation of c-Jun. Key words vascular smooth muscle cells, angiotensinogen, AP-1, c-Jun, transcription regulation