Mitogenic effect of orphan receptor TR3 and its regulation by MEKK1 in lung cancer cells
Mitogenic effect of orphan receptor TR3 and its regulation by MEKK1 in lung cancer cells
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DOI：
10.1128/mcb.23.23.8651-8667.2003
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发表时间：
2003-12-01
影响因子：
5.3
通讯作者：
Zhang, XK
中科院分区：
文献类型：
--
作者：
Kolluri, SK;Bruey-Sedano, N;Zhang, XK
TR 3，也称为NGFI-B或nur 77，是一种立即早期反应基因，是类固醇/甲状腺/类维生素A受体超家族的孤儿成员。我们以前报道过TR 3的表达是由凋亡刺激诱导的，并且是它们在肺癌细胞中的凋亡作用所必需的。在这里，我们提出的证据表明，TR 3也诱导表皮生长因子（EGF）和血清，并需要在肺癌细胞中的促有丝分裂作用。TR 3在H460和Calu-6肺癌细胞系中的异位表达促进其细胞周期进程和BrdU掺入，而通过小干扰RNA方法抑制TR 3表达抑制EGF和血清的促有丝分裂作用。对TR 3突变体的分析表明，TR 3 DNA结合和反式激活是其促有丝分裂作用所必需的。相反，它们因其凋亡活性而受到质疑。此外，共聚焦显微镜分析表明，TR 3在细胞核中起作用以诱导细胞增殖，而它作用于线粒体以诱导细胞凋亡。在检查调节TR 3的促有丝分裂功能的信号传导中，我们观察到组成型活性MEKK 1的共表达抑制TR 3的转录活性和TR 3诱导的增殖。MEKK 1的抑制作用是通过激活Jun N-末端激酶介导的，该激酶有效地磷酸化TR 3，导致其DNA结合丧失。总之，我们的结果表明，TR 3能够在相同的细胞中诱导增殖和凋亡，这取决于刺激及其细胞定位。
TR3, also known as NGFI-B or nur77, is an immediate-early response gene and an orphan member of the steroid/thyroid/retinoid receptor superfamily. We previously reported that TR3 expression was induced by apoptotic stimuli and was required for their apoptotic effect in lung cancer cells. Here, we present evidence that TR3 was also induced by epidermal growth factor (EGF) and serum and was required for their mitogenic effect in lung cancer cells. Ectopic expression of TR3 in both H460 and Calu-6 lung cancer cell lines promoted their cell cycle progression and BrdU incorporation, while inhibition of TR3 expression by the small interfering RNA approach suppressed the mitogenic effect of EGF and serum. Analysis of TR3 mutants showed that both TR3 DNA binding and transactivation were required for its mitogenic effect. In contrast, they were dispensable for its apoptotic activity. Furthermore, confocal microscopy analysis demonstrated that TR3 functioned in the nucleus to induce cell proliferation, whereas it acted on mitochondria to induce apoptosis. In examining the signaling that regulates the mitogenic function of TR3, we observed that coexpression of constitutive-active MEKK1 inhibited TR3 transcriptional activity and TR3-induced proliferation. The inhibitory effect of MEKK1 was mediated through activation of Jun N-terminal kinase, which efficiently phosphorylated TR3, resulting in loss of its DNA binding. Together, our results demonstrate that TR3 is capable of inducing both proliferation and apoptosis in the same cells depending on the stimuli and its cellular localization.