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Mechanisms for regulation of activation of innate immunity by a nuclear protein, IκB-ζ which functions in both acceleration and inhibition of transcription

核蛋白 IκB-ζ 调节先天免疫激活的机制，该蛋白在加速和抑制转录方面发挥作用

基本信息

批准号：
15370059
负责人：
MUTA Tatsushi
金额：
$ 9.66万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

We analyzed molecular functions, mechanisms for transcriptional regulation, and mechanisms for stimuli-specific induction of IκB-ζ, which function in both acceleration and inhibition of transcription of genes on inflammation. Firstly, we identified a nuclear localization signal in a region of amino acids 153-157 of IκB-ζ and a domain with transcriptional activation activity in a region of amino acids 329-402. Furthermore, we found that overexpression of IκB-ζ resulted in inhibition of tumor necrosis factor (TNF)-α production and acceleration of interleukin (IL)-6 production, on transcriptional level, upon stimulation with lipopolysaccharide (LPS). Analyses on IκB-ζ gene-disrupted mice revealed that IκB-ζ-deficient macrophages produced normal levels of TNF-α and nitric oxide in response to LPS, but IL-6 production was abolished, and that, in vivo, IL-12 production upon treatment with LPS was impaired whereas TNF-α production was strongly augmented. Secondly, promoter analyses of genes whose transcription is accelerated by IκB-ζ showed that NF-κB binding sites in the promoter is essential for the IκB-ζ-mediated transcriptional activation, but not sufficient and another cis-element is required for the activation. Thus, the presence of the cis-element determines the function of IκB-ζ on each promoter. Thirdly, regarding the mechanisms for stimuli-specific induction of IκB-ζ, we found that stability of IκB-ζ mRNA is strongly up-regulated upon stimulation with LPS or IL- 1β, but not with TNF-α. Furthermore, we found that a sequence in the 3'-untranslated region of IκB-ζ mRNA determines the stimuli-specific induction of IκB-ζ by post-transcriptional level. Therefore, IκB-ζ is one of key players in regulation of inflammatory responses, which is specifically induced upon stimulation of innate immunity, and is essential for the expression of a subset of inflammatory genes while it inhibits the expression of another subset of genes.

我们分析了IκB-κ B的分子功能、转录调控机制和刺激特异性诱导机制，IκB-κ B在炎症基因转录的加速和抑制中发挥作用。首先，我们在IκB-κ B的153-157位氨基酸区域鉴定了核定位信号，在329-402位氨基酸区域鉴定了具有转录激活活性的结构域。此外，我们发现，IκB-β的过表达导致在转录水平上抑制肿瘤坏死因子（TNF）-α的产生，并在脂多糖（LPS）刺激下促进白细胞介素（IL）-6的产生。对IκB-ζ基因破坏小鼠的分析表明，IκB-ζ缺陷型巨噬细胞在对LPS的反应中产生正常水平的TNF-α和一氧化氮，但IL-6的产生被消除，并且在体内，IL-12的产生在用LPS处理后受到损害，而TNF-α的产生强烈增加。第二，对IκB-β能促进转录的基因的启动子分析表明，启动子中的NF-κB结合位点对于IκB-β介导的转录激活是必需的，但不是足够的，并且需要另一个顺式元件来激活。因此，顺式元件的存在决定了IκB-κ B在每个启动子上的功能。第三，关于IκB-β的刺激特异性诱导机制，我们发现IκB-β mRNA的稳定性在LPS或IL- 1β刺激后强烈上调，但在TNF-α刺激下不上调。此外，我们还发现IκB-β mRNA 3 '端非翻译区的一个序列通过转录后水平决定了IκB-β的刺激特异性诱导。因此，IκB-κ B是调节炎症反应的关键参与者之一，其在刺激先天免疫时特异性地被诱导，并且对于一个亚组的炎症基因的表达是必需的，同时它抑制另一个亚组的基因的表达。