PU.1 and multiple IFN regulatory factor proteins synergize to mediate transcriptional activation of the human IL-1β gene
PU.1 and multiple IFN regulatory factor proteins synergize to mediate transcriptional activation of the human IL-1β gene
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DOI：
10.4049/jimmunol.166.11.6829
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发表时间：
2001-06-01
影响因子：
4.4
通讯作者：
Fenton, MJ
中科院分区：
文献类型：
--
作者：
Marecki, S;Riendeau, CJ;Fenton, MJ
淋巴细胞和骨髓细胞都表达IFN调节因子（IRF）家族转录因子的两个相关成员，特别是IRF-4和IFN共有结合蛋白（ICSBP或IRF-8）。我们以前报道过巨噬细胞表达IRF-4，并与ETS样蛋白PU.1结合可以协同激活人IL-1 β报告基因。在这里，我们报告说，这种协同作用是介导的复合PU.1/IRF元件位于上游增强子内，已知赋予细胞因子和LPS诱导的表达。在巨噬细胞中，IL-1 β报告基因表达的协同激活优先由IRF-4介导，而IRF-4和ICSBP在成纤维细胞中共表达时同样能够与PU. 1协同。此外，IRF-1和IRF-2的共表达显著增加了PU.1/IRF-4和PU.1/ICSBP诱导成纤维细胞中IL-1 β报告基因表达的能力。观察到的IRF-1和IRF-2共表达的额外协同作用由不同于IL-1 β增强子或启动子的DNA区域介导。我们还评估了这些转录因子在人胚肾293细胞中过表达时激活内源性IL-1 β基因的能力。尽管PU.1单独异位表达足以激活中等水平的IL-1 β转录物，但在额外IRF蛋白共表达后，内源性IL-1 β表达显著增加。因此，在共表达PU.1、IRF-4（或ICSBP）、IRF 1和IRF 2的细胞中观察到人IL-1 β报告基因和内源性IL-1 β基因的最大表达。总之，我们的观察表明，这些因素可能作为增强体一起发挥作用。
Both lymphoid and myeloid cells express two related members of the IFN regulatory factor (IRF) family of transcription factors, specifically IRF-4 and IFN consensus binding protein (ICSBP or IRF-8). We previously reported that macrophages express IRF-4 and in combination with the ETS-like protein PU.1 can synergistically activate a human IL-1 beta reporter gene. Here we report that this synergy is mediated by a composite PU.1/IRF element located within an upstream enhancer known to confer cytokine- and LPS-inducible expression. In macrophages, synergistic activation of IL-1 beta reporter gene expression was preferentially mediated by IRF-4, whereas IRF-4 and ICSBP were equally capable of synergizing with PU.1 when coexpressed in fibroblasts. Furthermore, coexpression of IRF-1 and IRF-2 dramatically increased the capacity of both PU.1/IRF-4 and PU.1/ICSBP to induce IL-1 beta reporter gene expression in fibroblasts. The additional synergy observed with IRF-1 and IRF-2 coexpression is mediated by a region of DNA distinct from either the IL-1 beta enhancer or promoter. We also assessed the capacity of these transcription factors to activate endogenous IL-1 beta gene when overexpressed in human embryonic kidney 293 cells. Although ectopic expression of PU.1 alone was sufficient to activate modest levels of IL-1 beta transcripts, endogenous IL-1 beta expression was markedly increased following coexpression of additional IRF proteins. Thus, maximal expression of both a human IL-1 beta reporter gene and the endogenous IL-1 beta gene was observed in cells that coexpressed PU.1, IRF-4 (or ICSBP), IRF1, and IRF2. Together, our observations suggest that these factors may function together as an enhanceosome.