CD28 mediates transcriptional upregulation of the interleukin-2 (IL-2) promoter through a composite element containing the CD28RE and NF-IL-2B AP-1 sites
CD28 mediates transcriptional upregulation of the interleukin-2 (IL-2) promoter through a composite element containing the CD28RE and NF-IL-2B AP-1 sites
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DOI：
10.1128/mcb.17.7.4051
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发表时间：
1997-07-01
影响因子：
5.3
通讯作者：
Weiss, A
中科院分区：
文献类型：
--
作者：
Shapiro, VS;Truitt, KE;Weiss, A
诱变研究已经证明，白介素2(IL-2)启动子中的CD28反应元件(CD28RE)是CD28上调转录所必需的。在这里，我们证明了CD28的反应性是由同时含有CD28RE和NF-IL-2B AP-L位点的复合元件(RE/AP)赋予的，RE/AP复合元件中任一位点的突变都会取消活性，RE/AP复合元件是IL-2启动子内的信号整合部位，因为它的激活依赖于至少两条独立的信号通路被激活，通过T细胞受体、CD28和/或佛波酯，当这三种信号同时出现时，激活最大，通过使用一组CD28细胞质结构域突变体，研究发现，RE/AP复合元件的转录激活与这些突变体在刺激下诱导的IL-2分泌模式密切相关，类似于IL-2分泌的上调，CD28对RE/AP复合元件的转录上调是FK506不敏感的。RE/AP复合元件的激活模式不同于NFAT或共识AP-1位点的激活模式，这意味着RE/AP代表一个独特的元件。利用凝胶位移分析，我们证明了CD28刺激诱导NF-KB家族成员c-Rel与RE/AP复合元件中的CD28RE结合，因此CD28对IL-2的转录上调似乎是通过RE/AP复合元件介导的，涉及c-REL与CD28RE的结合。
Mutagenesis studies have demonstrated the requirement for the CD28-responsive element (CD28RE) within the interleukin-2 (IL-2) promoter for transcriptional upregulation by CD28. Here, we demonstrate that CD28 responsiveness is conferred by a composite element containing both the CD28RE and the NF-IL-2B AP-l sites (RE/AP), Mutations at either site within the RE/AP composite element abolish activity, The RE/AP composite element is a site for signal integration within the IL-2 promoter, since its activation is dependent on at least two separate signalling pathways being activated, through the T-cell receptor, CD28, and/or phorbol myristate acetate, Activation is maximal when all three signals occur simultaneously, By using a panel of CD28 cytoplasmic domain mutants, it was found that the transcriptional activation of the RE/AP composite element correlates exactly with the pattern of IL-2 secretion induced by these mutants upon stimulation, Similar to the upregulation of IL-2 secretion, the transcriptional upregulation of the RE/AP composite element by CD28 is FK506 insensitive. The pattern of activation of the RE/AP composite element is different from that observed for either an NFAT or consensus AP-1 site, implying that RE/AP represents a unique element, Using gel shift analysis, we demonstrate that stimulation by CD28 induces the association of the NF-KB family member c-Rel to the CD28RE within the RE/AP composite element, The transcriptional upregulation of IL-2 by CD28 appears, therefore, to be mediated through the RE/AP composite element, involving the association of c-Rel with the CD28RE.