The p53 inhibitors MDM2/MDMX complex is required for control of p53 activity in vivo
The p53 inhibitors MDM2/MDMX complex is required for control of p53 activity in vivo
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p53 抑制剂 MDM2/MDMX 复合物是控制体内 p53 活性所必需的
DOI：
10.1073/pnas.1102309108
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发表时间：
2011-07-19
影响因子：
11.1
通讯作者：
Yuan, Zhi-Min
中科院分区：
文献类型：
--
作者：
Huang, Lei;Yan, Zheng;Yuan, Zhi-Min
目前提出了两种不同的模型来解释为什么MDM2和MDMX在p53控制中都是必需的，关键的区别在于这两种p53抑制剂是共同作用还是单独作用。为了测试这两种相互竞争的模型，我们产生了表达MDMX点突变（C462A）的敲入小鼠，该突变体在MDM2结合上存在缺陷。这种方法允许MDM2/MDMX异复合体的靶向解离，而不影响MDMX与p53结合的能力，同时使MDM2蛋白本身完全不受影响。值得注意的是，MdmxC462A/C462A纯合子小鼠在胚胎发育约9.5天死亡，这是由于细胞凋亡和细胞增殖减少的共同作用，分别通过TUNEL和BrdU掺入实验显示。有趣的是，尽管MDMX突变蛋白丰度在MdmxC462A/C462A纯合子胚胎中略有升高，但p53的丰度和活性均显著增加。通过发现p53的同时缺失完全挽救了MdmxC462A/C462A纯合小鼠的胚胎致死性，证实了p53依赖性死亡。我们的数据表明，MDM2和MDMX在p53控制中作为一个完整的复合体起作用，为MDM2和MDMX功能的非冗余性提供了见解。
There are currently two distinct models proposed to explain why both MDM2 and MDMX are required in p53 control, with a key difference centered on whether these two p53 inhibitors work together or independently. To test these two competing models, we generated knockin mice expressing a point mutation MDMX mutant (C462A) that is defective in MDM2 binding. This approach allowed a targeted disassociation of the MDM2/MDMX heterocomplex without affecting the ability of MDMX to bind to p53, and while leaving the MDM2 protein itself completely untouched. Significantly, MdmxC462A/C462A homozygous mice died at approximately day 9.5 of embryonic development, as the result of a combination of apoptosis and decreased cell proliferation, as shown by TUNEL and BrdU incorporation assays, respectively. Interestingly, even though the MDMX mutant protein abundance was found slightly elevated in the MdmxC462A/C462A homozygous embryos, both the abundance and activity of p53 were markedly increased. A p53-dependent death was demonstrated by the finding that concomitant deletion of p53 completely rescued the embryonic lethality in MdmxC462A/C462A homozygous mice. Our data demonstrate that MDM2 and MDMX function as an integral complex in p53 control, providing insights into the nonredundant nature of the function of MDM2 and MDMX.