Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto, Japan.
Oncogene. 2010 Apr 8;29(14):2060-9. doi: 10.1038/onc.2009.483. Epub 2010 Jan 18.
The tumor suppressor protein p53 has a critical role in safeguarding the integrity of the genome. Its functions are well understood but factors responsible for the transcriptional regulation of the p53 gene are almost entirely unknown. The DNA replication-related element (DRE)/DNA replication-related element-binding factor (DREF) transcriptional regulatory system is established as a master key to cell proliferation in Drosophila. DREF binds specifically to DRE sequences in the Drosophila p53 (dmp53) gene promoter as shown using anti-DREF antibodies in chromatin immunoprecipitation assays. Furthermore, a rough eye phenotype because of overexpression of DREF in Drosophila eye imaginal disks could be suppressed by half dose reduction of the dmp53 gene. In addition, the level of mRNA of dmp53 was decreased in DREF-knockdown cells and transient expression of the luciferase gene under control of the wild-type dmp53 gene promoter showed strong promoter activity in S2 cells, but this was almost completely abrogated with a DRE-mutated promoter. Requirement of DREs for dmp53 promoter activity was further confirmed by anti-beta-galactosidase antibody-staining of various tissues from transgenic flies carrying dmp53 promoter-lacZ fusion genes. These results indicate that DREF is necessary for dmp53 gene promoter activity.
抑癌蛋白 p53 在保护基因组完整性方面具有关键作用。其功能已得到充分理解，但负责 p53 基因转录调控的因素几乎完全未知。DNA 复制相关元件 (DRE)/DNA 复制相关元件结合因子 (DREF) 转录调控系统已被确立为调控果蝇细胞增殖的关键。正如在染色质免疫沉淀测定中使用抗 DREF 抗体所表明的那样，DREF 特异性结合到果蝇 p53 (dmp53) 基因启动子中的 DRE 序列。此外，在果蝇眼盘中外源表达 DREF 会导致粗糙眼表型，而 dmp53 基因的半剂量减少可以抑制这种表型。此外，DREF 敲低细胞中的 dmp53 mRNA 水平降低，并且在 S2 细胞中，受野生型 dmp53 基因启动子控制的荧光素酶基因的瞬时表达显示出很强的启动子活性，但在 DRE 突变启动子时几乎完全被消除。通过携带 dmp53 启动子-β半乳糖苷酶融合基因的转基因果蝇的各种组织的抗-β半乳糖苷酶抗体染色进一步证实了 DRE 对 dmp53 启动子活性的要求。这些结果表明 DREF 是 dmp53 基因启动子活性所必需的。
