Department of Molecular Biology, Faculty of Science, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen, Nijmegen, The Netherlands.
PLoS One. 2011 Mar 4;6(3):e17574. doi: 10.1371/journal.pone.0017574.
The tumor suppressor p53 plays a crucial role in cellular growth control inducing a plethora of different response pathways. The molecular mechanisms that discriminate between the distinct p53-responses have remained largely elusive. Here, we have analyzed the p53-regulated pathways induced by Actinomycin D and Etoposide treatment resulting in more growth arrested versus apoptotic cells respectively. We found that the genome-wide p53 DNA-binding patterns are almost identical upon both treatments notwithstanding transcriptional differences that we observed in global transcriptome analysis. To assess the role of post-translational modifications in target gene choice and activation we investigated the genome-wide level of phosphorylation of Serine 46 of p53 bound to DNA (p53-pS46) and of Serine 15 (p53-pS15). Interestingly, the extent of S46 phosphorylation of p53 bound to DNA is considerably higher in cells directed towards apoptosis while the degree of phosphorylation at S15 remains highly similar. Moreover, our data suggest that following different chemotherapeutical treatments, the amount of chromatin-associated p53 phosphorylated at S46 but not at pS15 is higher on certain apoptosis related target genes. Our data provide evidence that cell fate decisions are not made primarily on the level of general p53 DNA-binding and that post-translationally modified p53 can have distinct DNA-binding characteristics.
抑癌基因 p53 在细胞生长控制中起着至关重要的作用，它可以诱导多种不同的反应途径。区分不同 p53 反应的分子机制在很大程度上仍未被揭示。在这里，我们分析了放线菌素 D 和依托泊苷处理诱导的 p53 调节途径，分别导致更多的生长停滞和凋亡细胞。我们发现，尽管在全基因组转录组分析中观察到转录差异，但两种处理后 p53 的全基因组 DNA 结合模式几乎相同。为了评估翻译后修饰在靶基因选择和激活中的作用，我们研究了与 DNA 结合的 Ser46 磷酸化的 p53（p53-pS46）和 Ser15 磷酸化的 p53（p53-pS15）的全基因组水平。有趣的是，在导向凋亡的细胞中，与 DNA 结合的 p53 的 S46 磷酸化程度要高得多，而 S15 的磷酸化程度则非常相似。此外，我们的数据表明，在接受不同化疗药物治疗后，在某些与凋亡相关的靶基因上，与染色质相关的 S46 磷酸化的 p53 而非 S15 磷酸化的 p53 的量更高。我们的数据提供了证据表明，细胞命运的决定不是主要基于一般的 p53 DNA 结合水平，并且翻译后修饰的 p53 可以具有不同的 DNA 结合特征。
