Tong T, Fan W, Zhao H, Jin S, Fan F, Blanck P, Alomo I, Rajasekaran B, Liu Y, Holbrook N J, Zhan Q
Department of Radiation Oncology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
Exp Cell Res. 2001 Sep 10;269(1):64-72. doi: 10.1006/excr.2001.5312.
The p53-regulated stress-inducible gene GADD45 has been shown to participate in cellular response to DNA damage, including cell cycle checkpoint, apoptosis, and DNA repair. However, the regulation of GADD45 expression is complex and may involve both p53-dependent and -independent pathways. Recent findings have demonstrated that the p53-independent induction of GADD45 is mainly regulated by the transcription factors Oct-1 and NF-YA, which directly bind to their consensus motifs located at the GADD45 promoter region. Here, we report that mitogen-activated protein (MAP) kinases are involved in the induction of the GADD45 promoter after DNA damage. Inhibition of JNK1 and ERK kinase activities either by expression of the dominant negative mutant JNK1 or by treatment with a selective chemical inhibitor of ERK (PD098059) substantially abrogates the UV induction of the GADD45 promoter. In contrast, a p38 kinase inhibitor (SB203580) has little effect on GADD45 induction by UV. In addition, the GADD45 promoter is strongly activated following expression of JNK1; Raf-1, which is an upstream activator of the ERK pathway; or MEK1, an upstream activator of both the ERK and the JNK pathways. Activation of the GADD45 promoter by MAP kinases does not require normal p53 function. Interestingly, the MAP kinase-regulatory effect appears to be mediated via OCT-1 and CAAT motifs since disruption of these sites abrogates activation of the GADD45 promoter by MAP kinases. Therefore, these findings indicate that the MAP kinase pathways are involved in the regulation of the p53-independent induction of the GADD45 promoter, probably via interaction with transcription factors that directly bind to OCT-1 and CAAT motifs.
p53调控的应激诱导基因GADD45已被证明参与细胞对DNA损伤的反应，包括细胞周期检查点、细胞凋亡和DNA修复。然而，GADD45表达的调控很复杂，可能涉及p53依赖和非依赖途径。最近的研究发现表明，GADD45的p53非依赖诱导主要由转录因子Oct-1和NF-YA调控，它们直接结合位于GADD45启动子区域的共有基序。在此，我们报告丝裂原活化蛋白（MAP）激酶参与DNA损伤后GADD45启动子的诱导。通过表达显性负突变体JNK1或用ERK的选择性化学抑制剂（PD098059）处理来抑制JNK1和ERK激酶活性，可显著消除紫外线对GADD45启动子的诱导。相反，p38激酶抑制剂（SB203580）对紫外线诱导GADD45的作用很小。此外，在表达JNK1、Raf-1（ERK途径的上游激活剂）或MEK1（ERK和JNK途径的上游激活剂）后，GADD45启动子被强烈激活。MAP激酶对GADD45启动子的激活不需要正常的p53功能。有趣的是，MAP激酶的调控作用似乎是通过OCT-1和CAAT基序介导的，因为破坏这些位点可消除MAP激酶对GADD45启动子的激活。因此，这些发现表明MAP激酶途径参与了GADD45启动子的p53非依赖诱导的调控，可能是通过与直接结合OCT-1和CAAT基序的转录因子相互作用来实现的。
