組蛋白乙醯基轉移酵素在脂多醣體刺激RAW 264.7 巨噬細胞引發環氧酵素-2表現之角色探討

在過去的研究證實，內毒素是誘導巨噬細胞活化的重要因子，巨噬細胞釋放的前列腺素E (Prostaglandin E2，PGE2) 為誘導發炎反應的重要因子之一；而PGE2的生成會受到COX-2的調控。研究指出內毒素可經由HAT誘導轉錄因子活化以調控基因表現。本論文所要探討的是在RAW 264.7巨噬細胞中，組蛋白乙醯基轉移酵素 (Histone acetyltransferase, HAT) 在內毒素誘導環氧化酵素-2 (Cyclooxygenase-2，COX-2) 表現分子機轉中所扮演的角色。結果顯示在RAW 264.7巨噬細胞中，給予anacardic acid ( HAT 抑制劑) 可抑制 lipopolysaccharide (LPS) 誘導COX-2蛋白表現，使用p300 siRNA 會降低LPS 誘導COX-2蛋白表現，且發現 anacardic acid 抑制LPS會誘導 HAT 活性。我們也發現LPS會誘導 p65 及Histone H3產生乙醯化，進一步發現給予anacardic acid 可抑制 LPS 誘導 p65 乙醯化及 ?羠-luciferase 的活性。給予anacardic acid 抑制 LPS 誘導Histone H3 乙醯化。且LPS會誘導 p65 及 p300 結合在 COX-2 promoter region 。綜合以上結果發現p300將 p65 及Histone H3乙醯化在LPS誘導COX-2蛋白表現扮演重要角色，藉此研究可以提供發展控制發炎反應及敗血性休克的新方法。

關鍵字

脂多醣體；組蛋白乙醯基轉移酵素；轉錄因子kB p65；環氧酵素-2；發炎

並列摘要

Previous study shown that endotoxin is an important factor increased macrophage activity. Among the bioactive substances produced by macrophages including of prostaglandin E2 (PGE2) has been found the important mediators of inflammation. The PGE2 synthesis is dependent on the cyclooxygenase-2 (COX-2) expression. Previous study shown that endotoxin increased histone acetyltransferase (HAT) activity which mediates transcription factor activation and induces gene expression. In this study, we examined the role of HAT in endotoxin-induced COX-2 expression in RAW 264.7 macrophages. Pretreatment of anacardic acid (inhibitor of HAT) inhibited lipopolysaccharide (LPS)-induced COX-2 expression in a dose-dependent manner in RAW 264.7 macrophages. p300 siRNA inhibited LPS-induced COX-2 expression and anacardic acid inhibited LPS-induced HAT activity in RAW 264.7 macrophages.. We found that LPS-induced p65 acetylation and ?綑stone H3 acetylation. Furthermore, pretreatment of anacardic acid inhibited LPS-induced p65 acetylation and ?羠-luciferase activity, and Histone H3 acetylaion. Moreover, LPS increased binding of p65 and p300 to COX-2 promoter region. Taken together, we demonstrated that Histone H3 and p65 acetylation play crucial roles in LPS-induced COX-2 expression, and provided a new target for development of novel therapy in inflammation and septic shock.

並列關鍵字

Lipopolysaccharide ； Histone acetyltransferase ； NF-kB p65 ； cyclooxygenase-2 ； inflammation

參考文獻

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組蛋白乙醯基轉移酵素在脂多醣體刺激RAW 264.7 巨噬細胞引發環氧酵素-2表現之角色探討

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