The proliferation-associated early response gene p22/PRG1 is a novel p53 target gene
The proliferation-associated early response gene p22/PRG1 is a novel p53 target gene
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增殖相关早期反应基因 p22/PRG1 是一种新型 p53 靶基因
作者：
H. Schäfer;A. Trauzold;T. Sebens;W. Deppert;U. Fölsch;W. Schmidt
新型早期反应基因 p22/PRG1 与细胞周期进入和各种细胞类型的增殖诱导有关，尽管其确切功能仍不清楚。 p22/PRG1 启动子区域包含一个 20bp 序列，与肿瘤抑制蛋白 p53 的共有结合基序相匹配。凝胶位移测定表明，p53 特异性结合源自 p22/PRG1 启动子的 p53 结合位点的寡核苷酸。氯霉素乙酰转移酶 (CAT) 报告基因检测证实该位点赋予 p22/PRG1 启动子 p53 依赖性转录活性。在 Hela 细胞中，p22/PRG1 启动子仅在与野生型表达质粒共转染时才会诱导 CAT 表达，但对于突变型 p53 则不然。类似地，在表达温度敏感突变体p53的大鼠胚胎成纤维细胞衍生细胞系clone-6中，CAT表达在许可温度（31°C）下可诱导，但在非许可温度（39°C）下不可诱导。在允许的温度下，该突变体 p53 向功能性 p53 的转化伴随着该细胞系中内源性 p22/PRG1 mRNA 水平的显着增加。大鼠脾细胞的 γ 辐射或 Hela 细胞的多柔比星处理增加了 p53 水平，随后平行激活了 p22/PRG1 和 p21/Waf1 的转录激活。我们的数据表明，p22/PRG1 转录是在 p53 依赖性细胞周期停滞和凋亡过程中由 p53 诱导的。因此，p22/PRG1 代表了 p53 转录激活的新靶点。
The novel early response gene p22/PRG1 is linked to cell cycle entry and the induction of proliferation in various cell types although its exact function is still unknown. The p22/PRG1 promoter region contains a 20 bp sequence matching the consensus binding motif for the tumor suppressor protein p53. Gel shift assays demonstrated that p53 specifically binds to an oligonucleotide derived from the p53 binding site of the p22/PRG1 promoter. Chloramphenicol acetyltransferase (CAT) reporter gene assays confirmed that this site confers p53-dependent transcriptional activity to the p22/PRG1 promoter. In Hela cells, p22/PRG1 promoter constructs induced CAT expression only when cotransfected with an expression plasmid for wild-type, but not for mutant p53. Similarly, CAT expression was inducible at the permissive (31°C) but not at the non-permissive temperature (39°C) in the rat embryo fibroblast-derived cell line clone-6 that expresses a temperature-sensitive mutant p53. Conversion of this mutant p53 to a functional p53 at the permissive temperature was accompanied by a significant increase of endogenous p22/PRG1 mRNA level in this cell line. γ-irradiation of rat splenocytes or doxorubicin-treatment of Hela cells increased p53 levels followed by transcriptional activation of p22/PRG1 and p21/Waf1 in parallel. Our data demonstrate that p22/PRG1 transcription is induced by p53 during p53-dependent cell cycle arrest and apoptosis. Therefore, p22/PRG1 represents a novel target for transcriptional activation by p53.