p53 Laboratory, Agency for Science, Technology, Singapore 138648.
Proc Natl Acad Sci U S A. 2012 Jan 31;109(5):1685-90. doi: 10.1073/pnas.1114173109. Epub 2012 Jan 17.
The p53 transcription factor modulates gene expression programs that induce cell cycle arrest, senescence, or apoptosis, thereby preventing tumorigenesis. However, the mechanisms by which these fates are selected are unclear. Our objective is to understand p53 target gene selection and, thus, enable its optimal manipulation for cancer therapy. We have generated targeted transgenic reporter mice in which EGFP expression is driven by p53 transcriptional activity at a response element from either the p21 or Puma promoter, which induces cell cycle arrest/senescence and apoptosis, respectively. We demonstrate that we could monitor p53 activity in vitro and in vivo and detect variations in p53 activity depending on the response element, tissue type, and stimulus, thereby validating our reporter system and illustrating its utility for preclinical drug studies. Our results also show that the sequence of the p53 response element itself is sufficient to strongly influence p53 target gene selection. Finally, we use our reporter system to provide evidence for p53 transcriptional activity during early embryogenesis, showing that p53 is active as early as embryonic day 3.5 and that p53 activity becomes restricted to embryonic tissue by embryonic day 6.5. The data from this study demonstrate that these reporter mice could serve as powerful tools to answer questions related to basic biology of the p53 pathway, as well as cancer therapy and drug discovery.
p53 转录因子调节细胞周期停滞、衰老或凋亡的基因表达程序，从而防止肿瘤发生。然而，这些命运是如何被选择的机制尚不清楚。我们的目标是了解 p53 靶基因的选择，从而使其能够为癌症治疗进行最佳的操作。我们已经生成了靶向转基因报告小鼠，其中 EGFP 表达由 p53 转录活性驱动，来自 p21 或 Puma 启动子的反应元件，分别诱导细胞周期停滞/衰老和凋亡。我们证明，我们可以在体外和体内监测 p53 活性，并根据反应元件、组织类型和刺激检测 p53 活性的变化，从而验证了我们的报告系统，并说明了其在临床前药物研究中的实用性。我们的结果还表明，p53 反应元件本身的序列足以强烈影响 p53 靶基因的选择。最后，我们使用我们的报告系统提供了在早期胚胎发生过程中 p53 转录活性的证据，表明 p53 在胚胎第 3.5 天就具有活性，并且 p53 活性在胚胎第 6.5 天之前局限于胚胎组织。这项研究的数据表明，这些报告小鼠可以作为回答与 p53 途径的基础生物学、癌症治疗和药物发现相关的问题的有力工具。
