CCAAT/enhancer-binding protein d (C/EBPd)為轉錄因子 C/EBP 家族的其中一個成員，在受到發炎物質刺激時，除了可調控與急性發炎反應有關之基因表現外，並且也參與著脂肪生成過程中之基因轉錄作用。已知 lipopolysaccharide (LPS)可活化老鼠巨噬細胞 C/EBPd 基因表現，然而於分子機制上其如何受到調控至今仍未完全釐清，因此本論文目主要探討在老鼠巨噬細胞(RAW264.7)中，LPS 誘導 C/EBPd 基因表現之機制為何？由實驗結果得知 LPS 所誘導之 C/EBPd 蛋白質及mRNA增加情形會受乙醯化蛋白酶抑制劑-trichostatin A (TSA) 所抑制。另外，在處理 phosphatase 2B 抑制劑-cyclosporin A (CsA)，也同樣發現其可抑制 LPS 所誘導之 C/EBPd蛋白質增加情形，於此推測在 LPS 引發 C/EBPd 基因表現上，蛋白質乙醯化及磷酸化扮演一定重要性角色。另一方面，利用一系列不同長度之5’端段切之 C/EBPd 啟動區報告基因進行分析，由實驗結果顯示-345至+29區域即足以調控 basal 及 LPS 誘導的 C/EBPd 啟動區活性，並利用點突變及雙突變之報告基因作進一步的分析，發現此段區域所包含的 Sp1 site (-120/-115 bp)、及 CRE site (-45/-38 bp)是重要的。更進一步以凝膠電泳位移測定的實驗來確認啟動區蛋白質結合情形，結果顯示 Sp1 與 Sp3 可結合至-120/-115之Sp1 site，而 CREB 與 c-Jun 可結合至 CRE site。再者，overexpressed c-Jun 及 Sp1 皆可促進 C/EBPd基因啟動區活性表現，但 CREB 對於啟動區活性卻無作用。由上述實驗結果可知，LPS 對於 C/EBPd基因啟動區的 responsive elements 位於 Sp1 site (-120/-115 bp)及 CRE site (-45/-38 bp)，且 Sp1 及 c-Jun 此兩蛋白質對於調控 C/EBPd 基因的轉錄活性是重要的。

　　CCAAT/enhancer-binding protein d (C/EBPd) belongs to a family of transcription regulators C/EBP that has been implicated in mediating the acute phase response to inflammatory stimuli and in controling of adipogenesis. It was reported that LPS activated the transcription of C/EBPd in mouse macrophage cell line RAW264.7. However, little is known about the molecular mechanism of C/EBPd induced by LPS. In this study, we used trichostatin A (TSA), a histone deacetylase inhibitor, and cyclosporin A (CsA), a phosphatase 2B inhibitor, to assess whether any post-translational modification of acetylation or phosphorylation are involved in the regulation of LPS-induced C/EBPd gene. In this report, we found that TSA inhibited LPS-induced protein and mRNA expression of C/EBPd, and CsA inhibited LPS-induced protein expression of C/EBPd. Moreover, we also studied the LPS responsive element in the C/EBPd promoter. Analysis of the 5'-deletion mutants revealed that the 5'-flanking region of C/EBPd promoter sequences between -345 to +29 bp were sufficient for basal and LPS-inducibility. Furthermore, analysis of point mutation or double mutation of C/EBPd promoter revealed that Sp1 (-120/-115 bp) and CRE (-45/-38 bp) sites were essential for LPS responsiveness. Gel shift assay was used to identify potential regulators of these LPS responsive elements. The results showed that Sp1 and Sp3 bound to the promoter region of Sp1 site (-120/-115 bp); CREB and c-Jun bound to the promoter region of CRE site. Additionally, overexpression of c-Jun and Sp1, but not of CREB increased the promoter activity of C/EBPd gene. These results suggested that the Sp1 (-120/-115 bp) and the CRE (-45/-38 bp) sites are essential for LPS-induced transcriptional activity of C/EBPd gene. Both of Sp1 and c-Jun were important factors which were able to enhance the transcriptional activity of C/EBPd gene

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