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HeLa细胞ezrin基因基本启动子区转录调控元件的鉴定

Identification of Transcriptional Regulatory Elements within Ezrin Gene Basal Promoter in HeLa Cells

  • 摘要: 目的 鉴定HeLa细胞中调控ezrin基因基本启动子活性的顺式作用元件,探讨ezrin基因在HeLa细胞的表达调控机制。 方法 采用碱基定点突变实验和双荧光素酶报告基因分析系统,检测在HeLa细胞中Sp1结合位点(-75/-69, 相对于转录起始位点)和AP-1结合位点(-64/-58)对人ezrin基因基本启动子活性的影响;采用电泳迁移率变动分析法(EMSA)实验,检测ezrin基因基本启动子区序列与HeLa细胞核蛋白提取物的特异性结合活性。 结果 在HeLa细胞中,单独删除和置换Sp1结合位点或AP-1结合位点,ezrin基因基本启动子活性降低50%左右;同时置换Sp1结合位点和AP-1结合位点,启动子活性几乎完全丧失。ezrin基因基本启动子序列能够与HeLa细胞核蛋白提取物相结合。 结论 HeLa细胞中,Sp1结合位点和AP-1结合位点为ezrin基因基本启动子区的重要转录调控元件,有可能存在某种转录因子与之结合,激活ezrin基因转录。

     

    Abstract: Objective To identify of the regulatory elements for human ezrin gene basal promoter activity in human cervical carcinoma cell line HeLa, and to elucidate the transcriptional regulatory mechanism of the ezrin gene in HeLa cells. Methods Effect of Sp1 binding site (-75/-69, relative to transcription start site) and AP-1 binding site (-64/-58) on the human ezrin gene basal promoter activity in HeLa cells was performed using site-directed mutagenesis and dual-luciferase reporter assay system. Specific binding activity of nuclear extracts from HeLa cells to the human ezrin gene basal promoter region was detected by electrophoretic mobility shift assay. Results Deletion and replacement either the Sp1 site or the AP-1 site remained approximately 50% ezrin basal promoter activity in HeLa cells, while replacement both the Sp1 and AP-1 sites nearly abolished this activity. Nuclear extracts from HeLa cells could bind to the basal promoter region of human ezrin gene. Conclusion The Sp1 and AP-1 sites are two important cis-elements for the human ezrin basal promoter activity, and some transcription factors possibly bind to the two elements to transactivate ezrin gene in HeLa cells.

     

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