The tumor suppressor protein p53 functions similarly to p63 and p73 in activating transcription in vitro
The tumor suppressor protein p53 functions similarly to p63 and p73 in activating transcription in vitro
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DOI：
10.4161/cbt.4.4.1619
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发表时间：
2005-02
影响因子：
3.6
通讯作者：
N. Mondal;J. Parvin
中科院分区：
文献类型：
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作者：
N. Mondal;J. Parvin
p53肿瘤抑制蛋白通过特异性基因激活发挥作用，以抑制细胞周期的通过并触发细胞凋亡。p53蛋白与p63和p73同源，p63和p73通过相同的启动子序列调节转录，但激活不同的基因。在这项研究中，我们测试了p53，p63和p73是否具有不同的转录激活机制，以及这种差异是否可以解释每个因子如何刺激不同基因组的转录。我们发现，当将p53与转录激活因子GAL 4-VP 16（两者都被归类为酸性激活因子）进行比较时，p53对转录的刺激依赖于低Mg 2+浓度和有限量的提取物。通过比较，GAL 4-VP 16对RNA合成的刺激不依赖于特定浓度的Mg 2+，但确实需要更高量的提取物，这表明p53依赖性基因激活不需要的某种因子在提取物中是限制性的。与p53和GAL 4-VP 16之间的差异相反，p63和p73都在与p53相似的条件下调节体外转录。所有三种蛋白质，纯化到接近同质，在结合p53反应元件中同样活跃，并且在使用裸DNA模板、使用从HeLa细胞纯化的组蛋白或超乙酰化组蛋白在染色质中重构的DNA模板刺激转录反应中同样活跃。这些结果表明，p63和p73依赖性转录激活的基因特异性取决于特定的细胞类型中存在的特定的共激活因子和与启动子结合的其他因子。
The p53 tumor suppressor protein functions via specific gene activation to inhibit passage through the cell cycle and to trigger apoptosis. The p53 protein is homologous to p63 and p73, proteins that regulate transcription via the same promoter sequences but which activate different genes. In this study we tested whether p53, p63, and p73 have different mechanisms of activating transcription and if such a difference could explain how each factor stimulates the transcription of distinct sets of genes. We found that when comparing p53 to the transcriptional activator, GAL4-VP16, both of which are classified as acidic activators, that stimulation of transcription by p53 is dependent upon low Mg2+ concentrations and limiting amounts of extract. By comparison, the stimulation of RNA synthesis by GAL4-VP16 was not dependent on a specific concentration of Mg2+ but did require higher amounts of extract, suggesting that a certain factor not required for p53- dependent gene activation was limiting in the extract. In contrast to the differences between p53 and GAL4-VP16, p63 and p73 both regulated transcription in vitro under similar conditions as did p53. All three proteins, purified to near homogeneity, were equally active in binding to the p53-response element, and equally active in stimulating transcription reactions using naked DNA templates, DNA templates reconstituted in chromatin using histones purified from HeLa cells, or hyperacetylated histones. These results argue that the gene specificity of p63 and p73 dependent activation of transcription depends upon specific coactivators present in the specific cell types and upon other factors bound to the promoters.