一氧化碳誘導環氧化 ? 乙表現之分子機制探討

一氧化碳誘導環氧化 ? 乙表現之分子機制探討

 血紅素氧化 ? (heme oxygenase) 是將血紅素 (heme) 降解產生膽綠素 / 膽紅素

、亞鐵離子和一氧化碳 (carbon monoxide) 。血紅素氧化 ? 的許多生理功能都 與其副產物一氧化碳有關，在許多細胞中，如其具有抗氧化、血管舒張、影響 週邊或中樞神經系統的神經傳導活性、抗發炎、抗細胞凋亡或者抗細胞增殖等 功能。一氧化碳釋出分子 (carbon monoxide-releasing molecules) 是一類新興藥 物試劑，在生物系統中，釋出的一氧化碳可以去調節細胞功能。本篇的研究中

，在微小膠質細胞 (microglia) 和巨噬細胞 (macrophage) 中，利用一氧化碳 釋出分子 (CO-RMs) 和一氧化碳氣體 (CO gas) (500ppm) 去檢測環氧化 ?-2 (c yclooxygenase-2, COX-2) 的表現。從西方墨點法 (Western blot) 和反轉錄 ?- 聚合 ? 連鎖反應 (reverse transcriptase-polymerase chain reaction, RT-PCR) 實驗 證實，在有脂多醣 (Lipopolysaccharide, LPS) 刺激的微小膠質細胞 (BV2 and EO C13.31) 和巨噬細胞 (RAW264.7) 中， CO-RMs 和 CO gas 可以抑制一氧化氮 合成 ?(inducible nitric oxide synthase, iNOS) 蛋白質和 mRNA 的表現。然而，

細胞無論是否受到 LPS 的刺激， CO-RMs 和 CO gas 都會增加 COX-2 的表現。

在訊息傳遞方面， CO-RMs 會誘導 MAPKs 及 Akt 磷酸化，且隨著時間的增加 磷酸化的表現也就愈明顯。另外，加入了 PKG 、 p38 、 Erk 、 JNK 抑制劑後

，會抑制掉 COX-2 的表現。根據實驗結果得知， CO 誘導 COX-2 的表現可能 是經由 PKG 、 p38 、 Erk 和 JNK 的路徑來傳達。我們更進一步想要探討，在 初級腦皮質細胞中經由 CO 處理而誘導 COX-2 表現是否是促成神經細胞死亡 的原因。

Study of the molecular mechanisms of carbon monoxide on the inducti on of cyclooxygenase-2 in macrophage and microglia



The enzyme heme oxygenase (HO) degrades heme to produce biliverdin/bilirubin, f

errous iron and carbon monoxide (CO). Many biological functions of HO have bee

n attributed to its enzymatic byproduct carbon monoxide (CO) that exhibits anti-oxi

dative, vasodilation, and neurotransmission activities in the central or peripheral ne

rvous system, as well as anti-inflammatory, anti-apoptotic, or anti-proliferative pote

ntial in many cells. Carbon monoxide-releasing molecules (CO-RMs) are emerging

as a new class of pharmacological agents that regulates important cellular function

by liberating CO in biological system. In this study, we used both CO-RMs and CO

gas to examine the regulation of cyclooxygenase-2 (COX-2) expression in microgli

a/macrophage. Western blot and RT-PCR analysis demonstrated that CO-RMs and

CO gas (500 ppm) significantly inhibited the protein and mRNA expression of indu

cible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-activated (BV2 and

EOC13.31) microglia and (RAW264.7) macrophage. However, CO-RMs and CO g

as up-regulated COX-2 expression in the cells with or without LPS. CO-RMs time-

dependently induced the phosphorylation of MAPKs and Akt. In addition, the indu

ction of COX-2 could be reversed by PKG, p38, Erk and JNK inhibitors. The result

s suggest that the induction of COX-2 expression by CO might mediate PKG, p38,

Erk and JNK. Further works are to investigate whether induction of COX-2 contrib

ute to the neuron death in primary cortical cells exposed to CO.