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
Role of Histone Acetyltransferase in Lipopolysaccharide -Induced Cyclooxygenase-2 Expression in RAW 264.7 Macrophages
中文摘要
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。
英文摘要
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.
