NF-κB-inducing kinase is involved in the activation of the CD28 responsive element through phosphorylation of c-Rel and regulation of its transactivating activity
NF-κB-inducing kinase is involved in the activation of the CD28 responsive element through phosphorylation of c-Rel and regulation of its transactivating activity
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DOI：
10.4049/jimmunol.176.8.4666
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发表时间：
2006-04-15
影响因子：
4.4
通讯作者：
Fresno, Manuel
中科院分区：
文献类型：
--
作者：
Sanchez-Valdepenas, Carmen;Martin, Angel G.;Fresno, Manuel
已有证据表明，核因子-kappaB诱导激酶(NIK)可能调节IL-2的合成。然而，其分子机制尚不清楚。在本研究中，我们发现NIK参与了CD3+CD28对IL-2转录的激活。来自Aly/Aly小鼠的脾T细胞(Nik蛋白缺陷)对IL-2和GM-CSF的分泌有严重的损害，但对CD3/CD28的分泌没有影响。这种作用发生在转录水平，因为过表达的alyNIK抑制了IL-2启动子的转录。NIK激活IL-2启动子的CD28反应元件(CD28RE)，并与c-Rel在这一活动中有很强的协同作用。我们发现Nik与c-Rel的N-末端结构域相互作用，将这种相互作用映射到Nik的AA771-947。此外，Nik还能磷酸化c-Rel的C-末端反式激活结构域(TAD)，并诱导Gal4-c-Rel反式激活活性。抗CD28可激活Gal4-c-Rel的反式激活活性，但这种作用可被Nik缺陷突变体抑制。缺失研究定位了aa 456-540中对Nik反应的c-rel区域。一些丝氨酸的突变，包括丝氨酸(471)，在tAD的c-rel中，取消了其反式激活活性的Nik增强活性。有趣的是，表达c-rel突变之一的Jurkat突变细胞系(Ser(471)ASN)对CD3/CD28或Nik的反应存在严重的IL-2和CD28RE依赖的转录缺陷。我们的结果支持Nik可能通过调节TAD的c-Rel磷酸化来控制CD28RE依赖的转录和T细胞的激活。这导致依赖于c-rel结合的CD28RE位点的基因更有效地反式激活，如IL-2启动子。
Previous evidence suggested that NF-kappa B-inducing kinase (NIK) might regulate IL-2 synthesis. However, the molecular mechanism is not understood. In this study, we shown that NIK is involved in CD3 plus CD28 activation of IL-2 transcription. Splenic T cells from aly/aly mice (that have a defective NIK protein) have a severe impairment in IL-2 and GM-CSF but not TNF secretion in response to CD3/CD28. This effect takes place at the transcriptional level as overexpression of alyNIK inhibits IL-2 promoter transcription. NIK activates the CD28 responsive element (CD28RE) of the IL-2 promoter and strongly synergizes with c-Rel in this activity. We found that NIK interacts with the N-terminal domain of c-Rel, mapping this interaction to aa 771-947 of NIK. Moreover, NIK phosphorylates the c-Rel C-terminal transactivation domain (TAD) and induces Gal4-c-Rel-transactivating activity. Anti-CD28 activated Gal4-c-Rel transactivation activity, and this effect was inhibited by a NIK-defective mutant. Deletion studies mapped the region of c-Rel responsive to NIK in aa 456-540. Mutation of several serines, including Ser(471), in the TAD of c-Rel abrogated the NIK-enhancing activity of its transactivating activity. Interestingly, a Jurkat mutant cell line that expresses one of the mutations of c-Rel (Ser(471)Asn) has a severe defect in IL-2 and CD28RE-dependent transcription in response to CD3/CD28 or to NIK. Our results support that NIK may be controlling CD28RE-dependent transcription and T cell activation by modulating c-Rel phosphorylation of the TAD. This leads to more efficient transactivation of genes which are dependent on CD28RE sites where c-Rel binds such as the IL-2 promoter.