TA*p63 and GTAp63 achieve tighter transcriptional regulation in quality control by converting an inhibitory element into an additional transactivation domain
TA*p63 and GTAp63 achieve tighter transcriptional regulation in quality control by converting an inhibitory element into an additional transactivation domain
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DOI：
10.1038/s41419-019-1936-z
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发表时间：
2019-09-17
影响因子：
9
通讯作者：
Doetsch, Volker
中科院分区：
文献类型：
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作者：
Pitzius, Susanne;Osterburg, Christian;Doetsch, Volker
P53同源基因p63在上皮组织发育和生殖细胞质量控制中发挥着重要作用。这两种功能由p63的两种不同亚型执行。它们由不同的启动子产生，导致具有N-末端反式激活结构域(TAp63)或截短形式(Delta Np63)的异构体。除了这两种N-末端异构体外，还发现了第三种N-末端更长的异构体，命名为TA*p63。在参与遗传质量控制的雄性生殖细胞中发现了第四种N端亚型GTAp63，它与TA*p63非常相似。在这里，我们表征了TA*p63α和GTAp63α，并表明它们的N-末端延伸稳定了较短的TAp63α蛋白采用的闭合且唯一的二聚体构象。这两种蛋白都可以被两个激酶Chk2和CK1激活，导致开放的四聚体状态。在这种构象中，N-末端延伸作为一个额外的反式激活结构域来增强转录活性。通过这一机制，相对于TAp63α，抑制和激活状态的蛋白质之间的转录活性差异得到增强。最后，我们用质谱仪证明了TA*p63α在乳腺癌细胞株Sum159和突变型P53蛋白水平上都有表达。在阿霉素治疗后，TA*p63α被激活，提供了一种潜在的抗癌新工具。
The p53 homolog p63 plays important roles in development of epithelial tissues and quality control in germ cells. These two functions are executed by two distinct isoforms of p63. They are created by different promotors resulting in isoforms having either an N-terminal transactivation domain (TAp63) or a truncated form (Delta Np63). In addition to these two N-terminal isoforms a third one with an even longer N-terminus, named TA*p63, has been found. A fourth N-terminal isoform, GTAp63, that closely resembles TA*p63 was discovered in male germ cells where it is involved in genetic quality control. Here, we characterize TA*p63 alpha and GTAp63 alpha and show that their N-terminal extensions stabilize the closed and only dimeric conformation adopted by the shorter TAp63 alpha protein. Both proteins can be activated by the two kinases Chk2 and CK1 resulting in the open tetrameric state. In this conformation, the N-terminal extension acts as an additional transactivation domain enhancing transcriptional activity. Through this mechanism, the difference in transcriptional activity between the repressed and the active state of the protein gets enhanced relative to TAp63 alpha. Finally, we show by mass spectrometry that TA*p63 alpha is expressed in the breast cancer cell line Sum159 at the protein level together with mutant p53. Upon doxorubicin treatment, TA*p63 alpha gets activated, providing a potential new tool to fight cancer.