The induction of cyclooxygenase-2 mRNA in macrophages is biphasic and requires both CCAAT enhancer-binding protein β (C/EBPβ) and C/EBPδ transcription factors
The induction of cyclooxygenase-2 mRNA in macrophages is biphasic and requires both CCAAT enhancer-binding protein β (C/EBPβ) and C/EBPδ transcription factors
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DOI：
10.1074/jbc.m108282200
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发表时间：
2001-12-28
影响因子：
4.8
通讯作者：
Poli, V
中科院分区：
文献类型：
--
作者：
Caivano, M;Gorgoni, B;Poli, V
前列腺素是激活巨噬细胞功能的重要介质，其诱导合成由环氧合酶-2 (COX-2) 介导。在这里，我们利用小鼠巨噬细胞 RAW264 以及源自转录因子 CCAAT 增强子结合蛋白 β (C/EBPbeta) 缺陷的小鼠的永生化巨噬细胞来探索调节活化巨噬细胞中 COX-2 诱导的分子机制。我们证明脂多糖介导的 COX-2 mRNA 诱导是双相的。初始阶段独立于从头蛋白质合成，与 cAMP 反应元件结合蛋白 (CREB) 激活相关，被消除 CREB 磷酸化和减少 NF-κB 介导的基因激活的治疗所抑制，并且需要转录因子 C/EBPbeta 的存在。另一方面，除了 C/EBPbeta 之外，C/EBPdelta 似乎对于影响 COX-2 基因转录的第二阶段也是必需的，这对于维持诱导状态很重要，并且需要从头合成蛋白质。事实上，C/EBPbeta-/- 巨噬细胞中 COX-2 诱导的两个阶段都有缺陷。此外，C/EBPδ 的合成通过脂多糖处理显着增加，并且与 COX-2 诱导一样，通过 MAPK 和 SAPK2/p38 级联的联合抑制而受到抑制。总而言之，这些数据确定 CREB、NF-kappaB 以及 C/EBPbeta 和 -delta 是协调协调激活巨噬细胞中 COX-2 启动子转录的关键因素。
Prostaglandins are important mediators of activated macrophage functions, and their inducible synthesis is mediated by cyclooxygenase-2 (COX-2). Here, we make use of the murine macrophage cells RAW264 as well as of immortalized macrophages derived from mice deficient for the transcription factor CCAAT enhancer-binding protein beta (C/EBPbeta) to explore the molecular mechanisms regulating COX-2 induction in activated macrophages. We demonstrate that lipopolysaccharide-mediated COX-2 mRNA induction is biphasic. The initial phase is independent of de novo protein synthesis, correlates with cAMP-response element-binding protein (CREB) activation, is inhibited by treatments that abolish CREB phosphorylation and reduce NF-kappaB-mediated gene activation, and requires the presence of the transcription factor C/EBPbeta. On the other hand, C/EBPdelta appears to be essential in addition to C/EBPbeta to effect the second phase of COX-2 gene transcription, which is important for maintaining the induced state and requires de novo protein synthesis. Indeed, both phases of COX-2 induction were defective in C/EBPbeta-/- macrophages. Moreover, the synthesis of C/EBPdelta was increased dramatically by treatment with lipopolysaccharide and, like COX-2 induction, repressed by combined inhibition of the MAPK and of the SAPK2/p38 cascades. Taken together, these data identify CREB, NF-kappaB, and both C/EBPbeta and -delta as key factors in coordinately orchestrating transcription from the COX-2 promoter in activated macrophages.