Key Laboratory of Human Functional Genomics of Jiangsu Province, Clinical Diabetes Centre of Jiangsu Province, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, China.
Arch Biochem Biophys. 2011 Jan 1;505(1):123-9. doi: 10.1016/j.abb.2010.09.016. Epub 2010 Sep 22.
Cyclooxygenase-2 (COX-2) plays important roles in the development of many disease conditions, including pancreatic β-cell dysfunction. Although the processes involved in the transcriptional regulation of COX-2 are well documented, some key elements, especially inhibitory elements, are still unknown. In our previous study, we identified a novel repressor element located in promoter region of mouse COX-2. In this study, we isolated several DNA-binding proteins from NIT-1 cells via DNA affinity chromatography; the most prominent among these proteins was poly (ADP-ribose) polymerase-1 (PARP-1). In this study, gel-supershift assays and chromatin immunoprecipitation assays showed that PARP-1 can bind to the inhibitory element -655/-632 in the promoter region of mouse COX-2 both in vitro and in vivo. Furthermore, overexpression of PARP-1 significantly inhibited promoter activity and decreased COX-2 expression. Conversely, repression of PARP-1 by RNAi upregulated COX-2 expression. These data suggest that PARP-1 plays an important role in the regulation of COX-2 expression via binding to the inhibitory element. Collectively, our findings provide new important information on the transcriptional regulation of COX-2 in pancreatic β-cells.
环氧化酶-2（COX-2）在许多疾病的发展中发挥着重要作用，包括胰腺β细胞功能障碍。虽然 COX-2 的转录调控过程已有详细记录，但一些关键元件，特别是抑制元件，仍不清楚。在我们之前的研究中，我们在小鼠 COX-2 的启动子区域中鉴定了一个新的抑制元件。在这项研究中，我们通过 DNA 亲和层析从 NIT-1 细胞中分离出几种 DNA 结合蛋白；其中最突出的是聚（ADP-核糖）聚合酶-1（PARP-1）。在这项研究中，凝胶超迁移分析和染色质免疫沉淀分析表明，PARP-1 可以在体外和体内与小鼠 COX-2 启动子区域的抑制元件 -655/-632 结合。此外，PARP-1 的过表达显著抑制了启动子活性并降低了 COX-2 的表达。相反，通过 RNAi 抑制 PARP-1 表达则上调了 COX-2 的表达。这些数据表明，PARP-1 通过与抑制元件结合在调节 COX-2 表达中起重要作用。总的来说，我们的研究结果为胰腺β细胞中 COX-2 的转录调控提供了新的重要信息。
