Wang Shuibang, Zhang Jianhua, Theel Stephanie, Barb Jennifer J, Munson Peter J, Danner Robert L
Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA.
Nucleic Acids Res. 2006 Jun 6;34(10):3044-56. doi: 10.1093/nar/gkl386. Print 2006.
Nitric oxide (NO*) can stabilize mRNA by activating p38 mitogen-activated protein kinase (MAPK). Here, transcript stabilization by NO* was investigated in human THP-1 cells using microarrays. After LPS pre-stimulation, cells were treated with actinomycin D and then exposed to NO* without or with the p38 MAPK inhibitor SB202190 (SB). The decay of 220 mRNAs was affected; most were stabilized by NO*. Unexpectedly, SB often enhanced rather than antagonized transcript stability. NO* activated p38 MAPK and Erk1/2; SB blocked p38 MAPK, but further activated Erk1/2. RT-PCR confirmed that NO* and SB could additively stabilize certain mRNA transcripts, an effect abolished by Erk1/2 inhibition. In affected genes, these responses were associated with CU-rich elements (CURE) in 3'-untranslated regions (3'-UTR). NO* stabilized the mRNA of a CURE-containing reporter gene, while repressing translation. Dominant-negative Mek1, an Erk1/2 inhibitor, abolished this effect. NO* similarly stabilized, but blocked translation of MAP3K7IP2, a natural CURE-containing gene. NO* increased hnRNP translocation to the cytoplasm and binding to CURE. Over-expression of hnRNP K, like NO*, repressed translation of CURE-containing mRNA. These findings define a sequence-specific mechanism of NO*-triggered gene regulation that stabilizes mRNA, but represses translation.
一氧化氮（NO*）可通过激活p38丝裂原活化蛋白激酶（MAPK）来稳定信使核糖核酸（mRNA）。在此，利用微阵列技术在人THP-1细胞中研究了NO介导的转录本稳定性。在脂多糖（LPS）预刺激后，用放线菌素D处理细胞，然后使其暴露于有或无p38 MAPK抑制剂SB202190（SB）的NO中。220种mRNA的降解受到影响；大多数被NO稳定。出乎意料的是，SB通常增强而非拮抗转录本稳定性。NO激活p38 MAPK和细胞外信号调节激酶1/2（Erk1/2）；SB阻断p38 MAPK，但进一步激活Erk1/2。逆转录聚合酶链反应（RT-PCR）证实，NO和SB可相加地稳定某些mRNA转录本，这种效应可被Erk1/2抑制所消除。在受影响的基因中，这些反应与3'-非翻译区（3'-UTR）中富含CU的元件（CURE）相关。NO稳定了含CURE的报告基因的mRNA，同时抑制翻译。显性负性Mek1（一种Erk1/2抑制剂）消除了这种效应。NO同样稳定了含天然CURE的基因MAP3K7IP2的mRNA，但阻断了其翻译。NO增加了不均一核糖核蛋白（hnRNP）向细胞质的转运及其与CURE的结合。hnRNP K的过表达与NO一样，抑制含CURE的mRNA的翻译。这些发现确定了一种NO触发的基因调控的序列特异性机制，该机制可稳定mRNA，但抑制翻译。
