Knockin mice expressing a Chimeric p53 protein reveal mechanistic differences in how p53 triggers apoptosis and senescence
Knockin mice expressing a Chimeric p53 protein reveal mechanistic differences in how p53 triggers apoptosis and senescence
复制标题
DOI：
10.1073/pnas.0706764105
复制
发表时间：
2008-01-29
影响因子：
11.1
通讯作者：
Attardi, Laura D.
中科院分区：
文献类型：
--
作者：
Johnson, Thomas M.;Meade, Kristin;Attardi, Laura D.
转录激活对p53效应器功能的贡献对于肿瘤抑制、细胞凋亡和细胞衰老至关重要，由于p53能够以非转录激活的方式调节多种细胞过程，因此仍不清楚。将反式激活的重要性与其他p53功能分离，包括调节转录抑制、DNA复制、同源重组、中心体复制和线粒体功能，一直很困难，因为这些功能在氨基末端的重叠基序。为了确定这些活动和反式激活p53功能的相对贡献，我们产生了敲入小鼠表达的p53突变体缺乏这些反式激活独立的功能域，同时通过融合到单纯疱疹病毒VP16反式激活域的反式激活。这种称为p53（VP16）的嵌合突变体强烈激活了一系列参与凋亡和衰老的p53靶点的转录。有趣的是，尽管具有反式激活能力，但这种嵌合蛋白在小鼠成纤维细胞中显示出p53效应子功能的选择性，具有在各种条件下触发衰老而不是凋亡的能力。我们的研究强调了p53反式激活对衰老的核心作用，同时表明反式激活对凋亡是不够的，并提供了深入了解p53作为肿瘤抑制因子的机制。
The contribution of transcriptional activation to the p53 effector functions critical for tumor suppression, apoptosis and cellular senescence, remains unclear because of p53's ability to regulate diverse cellular processes in a transactivation-independent manner. Dissociating the importance of transactivation from other p53 functions, including regulating transcriptional repression, DNA replication, homologous recombination, centrosome duplication, and mitochondrial function, has been difficult because of overlapping motifs for these functions in the amino terminus. To determine the relative contribution of these activities and transactivation to p53 function, we generated knockin mice expressing a p53 mutant lacking domains involved in these transactivation-independent functions, while remaining competent for transactivation through fusion to the Herpes Simplex Virus VP16 transactivation domain. This chimeric mutant, termed p53(VP16), robustly activates the transcription of a range of p53 targets involved in both apoptosis and senescence. Intriguingly, despite being transactivation-competent, this chimeric protein shows selectivity in p53 effector function in mouse fibroblasts, with a capacity to trigger senescence but not apoptosis under a variety of conditions. Our study highlights the central role of p53 transactivation for senescence while suggesting that transactivation is insufficient for apoptosis, and provides insight into the mechanisms by which p53 serves as a tumor suppressor.