Yao Ke, Cho Yong-Yeon, Bergen H Robert, Madden Benjamin J, Choi Bu Young, Ma Wei-Ya, Bode Ann M, Dong Zigang
Hormel Institute, University of Minnesota, Austin, Minnesota 55912, USA.
Cancer Res. 2007 Sep 15;67(18):8725-35. doi: 10.1158/0008-5472.CAN-06-4788.
The c-jun-NH(2)-kinases (JNK) play a critical role in tumor promoter-induced cell transformation and apoptosis. Here, we showed that the nuclear factor of activated T3 (NFAT3) is phosphorylated by JNK1 or JNK2 at Ser(213) and Ser(217), which are located in the conserved SP motif. The transactivation domain of NFAT3 is found between amino acids (aa) 113 and 260 and includes the phosphorylation targets of JNK1 and JNK2. NFAT3 transactivation activity was suppressed in JNK1(-/-) or JNK2(-/-) mouse embryonic fibroblast (MEF) cells compared with wild-type MEF cells. Moreover, a 3xNFAT-luc reporter gene assay indicated that NFAT3 transcriptional activity was increased in a dose-dependent manner by JNK1 or JNK2. Double mutations at Ser(213) and Ser(217) suppressed NFAT3 transactivation activity; and SP600125, a JNK inhibitor, suppressed NFAT3-induced 3xNFAT-luciferase activity. Knockdown of JNK1 or JNK2 suppressed foci formation in NIH3T3 cells. Importantly, ectopic expression of NFAT3 inhibited AP-1 activity and suppressed foci formation. Furthermore, knockdown of NFAT3 enhanced Ras-JNK1 or JNK2-induced foci formation in NIH3T3 cells. Taken together, these results provided direct evidence for the anti-oncogenic potential of the NFAT3 transcription factor.
c-Jun氨基末端激酶（JNK）在肿瘤启动子诱导的细胞转化和凋亡中起关键作用。在此，我们发现活化T3核因子（NFAT3）在位于保守SP基序中的Ser(213)和Ser(217)位点被JNK1或JNK2磷酸化。NFAT3的反式激活结构域位于氨基酸（aa）113至260之间，包括JNK1和JNK2的磷酸化靶点。与野生型小鼠胚胎成纤维细胞（MEF）相比，在JNK1(-/-)或JNK2(-/-)的MEF细胞中，NFAT3的反式激活活性受到抑制。此外，一项3xNFAT-荧光素酶报告基因检测表明，JNK1或JNK2可使NFAT3的转录活性呈剂量依赖性增加。Ser(213)和Ser(217)位点的双突变抑制了NFAT3的反式激活活性；JNK抑制剂SP600125抑制了NFAT3诱导的3xNFAT-荧光素酶活性。敲低JNK1或JNK2可抑制NIH3T3细胞中的病灶形成。重要的是，NFAT3的异位表达抑制了AP-1活性并抑制了病灶形成。此外，敲低NFAT3增强了Ras-JNK1或JNK2诱导的NIH3T3细胞中的病灶形成。综上所述，这些结果为NFAT3转录因子的抗癌潜力提供了直接证据。
