凋亡素与热休克蛋白70启动子区热休克元件特异结合诱导HepG2细胞凋亡

摘要

Objective To investigate the molecular mechanism of apoptin down-regulating HSP70 of Hepg2 cells and analyze the binding interaction between apoptin and HSE of the promoter region of HSP70. Methods The binding of apoptin and HSE was measured by elec-trophoretic mobility shift assay (EMSA). Luciferase reporter assay was used to further analyze the binding ability of apoptin to HSE in vitro. Result The result of EMSA showed that apoptin could bind to HSE of the promoter region of HSP70 in vitro directly. The higher the apoptin's concentration was,the greater capacity of binding to HSE was demonstrated. The result of luciferase reporter assay showed that the binding of apoptin to HSE was specific and there was competition between apoptin and HSF1 in binding to HSE. Conclusion The binding of apoptin to HSE of the promoter region of HSP70 inhibited the beginning of HSP70 transcription and remarkably down-regulated expression of HSP70. It also removed protection of HSP70 to tumor cells and induced apoptosis of tumor cells.%目的 探讨凋亡素下调HepG2细胞热休克蛋白70 (HSP70)的分子机制.分析凋亡素与HSP70启动子区热休克元件(HSE)的相互结合作用.方法 应用凝胶电泳迁移率分析(EMSA)法检测凋亡素与HSE的结合；荧光素酶报告基因实验进一步分析凋亡素在细胞内与HSE的结合能力.结果 EMSA结果表明凋亡素在体外和细胞水平可以直接与HSP70启动子区的HSE结合,凋亡素浓度越高,与HSE结合能力越强；Luciferase报告基因结果显示凋亡素对HSE具有专一的结合能力,揭示在与HSE结合上,凋亡素与HSF1间存在竞争关系.结论 凋亡素与HSP70启动子区HSE序列结合,抑制HSP70转录的起始,显著下调HSP70的表达,解除HSP70对肿瘤细胞的保护作用,诱导肿瘤细胞的凋亡.