The role of CCAAT/enhancer-binding protein beta in the transcriptional regulation of COX-2 in human amnion.
The role of CCAAT/enhancer-binding protein beta in the transcriptional regulation of COX-2 in human amnion.
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DOI：
10.1093/molehr/gah194
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发表时间：
2005-12
影响因子：
4
通讯作者：
Yun‐Sil Lee;V. Terzidou;T. Lindstrom;Mark Johnson;P. Bennett
中科院分区：
文献类型：
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作者：
Yun‐Sil Lee;V. Terzidou;T. Lindstrom;Mark Johnson;P. Bennett
人类分娩与子宫内通过诱导型 2 型环加氧酶 (COX-2) 的作用增加前列腺素合成有关。前列腺素的主要来源是胎膜，特别是羊膜，其中 COX-2 的表达在妊娠后期和分娩时增加。 COX-2基因启动子含有多个假定的转录因子结合位点，包括NF-κB、AP-1和C/EBP的结合位点，因此具有快速反应基因的特征。我们之前已经证明，在羊膜中，COX-2 启动子中的 NF-kappaB DNA 结合位点对于基因表达至关重要，并且随着分娩的开始，羊膜中 NF-kappaB 活性增加。在这项研究中，我们证明在原代人羊膜细胞中，CCAAT/增强子结合蛋白β (C/EBPβ) DNA 结合位点对于 COX-2 基因启动子的功能至关重要。在 COX-2 启动子内鉴定出三个潜在的 C/EBPbeta DNA 结合位点，这些位点显示与 C/EBPbeta 结合，但不与 C/EBPα、C/EBPdelta、CREB（cAMP 响应元件调节剂）或 CREM 结合。在瞬时转染研究中，对 COX-2 启动子中的三个 C/EBPβ 位点进行定点诱变的荧光素酶报告基因构建体显示荧光素酶表达降低。然而，对分娩前后获得的细胞的 C/EBPβ 蛋白水平及其 DNA 结合活性进行比较，未发现显着差异。这表明虽然C/EBPβ在COX-2的表达中起着重要的组成作用，但C/EBPβ可能不直接参与其与人类分娩相关的调节。
Human labour is associated with increased prostaglandin synthesis within the uterus by the action of the inducible type-2 cyclo-oxygenase enzyme (COX-2). A major source of prostaglandin is the fetal membranes, in particular the amnion, in which expression of COX-2 increases in late pregnancy and with labour. The COX-2 gene promoter contains several putative transcription factor binding sites including those for NF-kappaB, AP-1 and C/EBP and therefore has the features of a rapid response gene. We have previously shown that, in amnion, the NF-kappaB DNA-binding sites in the COX-2 promoter are essential for gene expression and that there is an increase in NF-kappaB activity in amnion with the onset of labour. In this study, we demonstrate that in primary human amnion cells, CCAAT/enhancer-binding protein beta (C/EBPbeta) DNA-binding sites are crucial for the function of the COX-2 gene promoter. Three potential C/EBPbeta DNA-binding sites were identified within the COX-2 promoter which were shown to bind to C/EBPbeta but not to C/EBPalpha, C/EBPdelta, CREB (cAMP responsive element modulator) or CREM. Luciferase reporter constructs with site-directed mutagenesis of the three C/EBPbeta sites in the COX-2 promoter showed reduced expression of luciferase in transient transfection studies. However, comparison of C/EBPbeta protein levels and their DNA-binding activity from cells obtained before and after labour showed no significant differences. This suggests that although C/EBPbeta plays an essential constitutive role in the expression of COX-2, C/EBPbeta may not be directly involved in its regulation in association with human labour.