Non-activated p53 co-localizes with sites of transcription within both the nucleoplasm and the nucleolus
Non-activated p53 co-localizes with sites of transcription within both the nucleoplasm and the nucleolus
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DOI：
10.1038/sj.onc.1203378
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发表时间：
2000-01-06
期刊：
影响因子：
8
通讯作者：
Milner, J
中科院分区：
文献类型：
--
作者：
Rubbi, CP;Milner, J
p53 肿瘤抑制因子充当基因毒性应激的传感器，一旦激活，就会诱导细胞生长停滞或凋亡。非应激细胞中潜在 p53 蛋白的精确核内定位尚不清楚。为了了解相对较少的 p53 分子如何检测和响应 DNA 损伤，此类信息至关重要。在这里，我们首次详细展示了正常生长条件下 p53 在细胞核中的超分子定位。我们表明，可溶性非结合 p53 通过透化作用释放，从而在细胞核和核仁中留下结构结合的 p53。原位生化研究揭示（i）核结合 p53 被 RNA（直接或间接）束缚，以及（ii）核结合 p53 的亚群与 RNA 合成位点共定位。转录共定位似乎与 p53 构象无关，但取决于其四级结构。在核仁中，在 rRNA 合成位点以及邻近这些位点处观察到 p53。相比之下，核仁 hdm-2（其他人证明它能复合 p53 和 5S RNA）被排除在 rRNA 合成位点之外。我们发现 p53 与转录位点物理相连，这可能解释了为什么相对较少的 p53 蛋白分子能够监测遗传应激并优先对活跃转录基因的损伤做出反应。
The p53 tumour suppressor functions as a sensor of genotoxic stress and, once activated, induces cell growth arrest or apoptosis, The precise intranuclear localization of latent p53 protein in non-stressed cells is unknown, Such information is essential in order to understand how relatively few molecules of p53 can detect and respond to DNA damage. Here we present the first detailed supramolecular localization of p53 in the nuclei of cells under normal conditions of growth, We show that soluble, non-bound p53 is released by permeabilization, leaving structurally bound p53 in both the nucleus and nucleolus. ln situ biochemical studies reveal (i) that nuclear-bound p53 is tethered by RNA (directly or indirectly) and (ii) that a sub-population of nuclear-bound p53 co-localizes with sites of RNA synthesis. Transcriptional co-localization appeared to be independent of p53 conformation but dependent upon its quaternary structure. In the nucleolus p53 was observed at sites of rRNA synthesis and also adjacent to such sites. In contrast, nucleolar hdm-2 (shown by others to complex p53 and 5S RNA) was excluded from sites of rRNA synthesis. Our discovery that p53 is physically linked with sites of transcription may explain how relatively few p53 protein molecules can monitor genetic stress and respond preferentially to damage of actively transcribed genes.