MEKK1/JNK signaling stabilizes and activates p53
MEKK1/JNK signaling stabilizes and activates p53
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DOI：
10.1073/pnas.95.18.10541
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发表时间：
1998-09-01
影响因子：
11.1
通讯作者：
Ronai, Z
中科院分区：
文献类型：
--
作者：
Fuchs, SY;Adler, V;Ronai, Z
应激和损伤刺激对肿瘤抑制因子 p53 的激活通常与应激激酶 Jun-NH(2) 激酶 (JNK) 的诱导相关。由于 JNK 与 p53 的关联在 p53 稳定性中起着重要作用，因此在本研究中，我们阐明了 JNK 信号通路与 p53 稳定性和活性之间的关系。 JNKK 上游激酶、丝裂原激活蛋白激酶激酶激酶 (Delta MEKK1) 的组成型活性形式的表达增加了 p53 null (10.1) 细胞中外源转染形式 p53 的水平以及 MCF7 乳腺癌细胞中内源 p53 的水平。 Delta MEKK1 的强制表达增加了 p53 水平，同时体内 p53 泛素化降低，并且 p53 半衰期延长。 JNK 结合位点（氨基酸 97-116；p7 区域）的计算机建模使我们能够设计该区域内暴露残基的突变。 p53 各自的突变（p53（101-5-8））和缺失（p53（Delta p7））形式在 Delta MEKK1 表达后并未表现出相同的 p53 水平增加。 JNK 对 p53 的体外磷酸化消除了 Mdm2 结合和 p53 泛素化的靶向。同样，Delta MEKK1 表达通过免疫纯化的 JNK 和解离的 p53-Mdm2 复合物增加了 p53 磷酸化。通过 mdm2 启动子驱动的荧光素酶测量，p53 的转录活性在 Delta MEKK1 表达细胞中表现出显着增加。将 p53 和 Delta MEKK1 共转染到 p53 缺失细胞中可增强 p53 依赖性细胞凋亡，表明 MEKK1 效应物有助于 p53 介导程序性细胞死亡的能力。我们的结果指出 MEKK1-JNK 信号在 p53 稳定性、转录活性和细胞凋亡能力中的作用，作为细胞应激反应的一部分。
Activation of the tumor suppressor p53 by stress and damage stimuli often correlates with induction of stress kinases, Jun-NH(2) kinase (JNK). As JNK association with p53 plays an important role in p53 stability, in the present study we have elucidated the relationship between the JNK-signaling pathway and p53 stability and activity. Expression of a constitutively active form of JNKK upstream kinase, mitogen-activated protein kinase kinase kinase (Delta MEKK1), increased the level of the exogenously transfected form of p53 in p53 null (10.1) cells as well as of endogenous p53 in MCF7 breast cancer cells. Increased p53 level by forced expression of Delta MEKK1 coincided with a decrease in p53 ubiquitination in vivo and with prolonged p53 half-life. Computerized modeling of the JNK-binding site (amino acids 97-116; p7 region) enabled us to design mutations of exposed residues within this region. Respective mutations (p53(101-5-8)) and deletion (p53(Delta p7)) forms of p53 did not exhibit the same increase in p53 levels upon Delta MEKK1 expression. In vitro phosphorylation of p53 by JNK abolished Mdm2 binding and targeting of p53 ubiquitination. Similarly, Delta MEKK1 expression increased p53 phosphorylation by immunopurified JNK and dissociated p53-Mdm2 complexes. Transcriptional activity of p53, as measured via mdm2 promoter-driven luciferase, exhibited a substantial increase in Delta MEKK1-expressing cells. Cotransfection of p53 and Delta MEKK1 into p53 null cells potentiated p53-dependent apoptosis, suggesting that MEKK1 effecters contribute to the ability of p53 to mediate programmed cell death. Our results point to the role of MEKK1-JNK signaling in p53 stability, transcriptional activities, and apoptotic capacity as part of the cellular response to stress.