肽聚醣經由 c-Src 和 NADPH 氧化酶之路徑誘導 RAW 264.7 巨噬細胞
環氧化酶 -2 的表現
肽聚醣 (peptidoglycan ； PGN) ，革蘭氏陽性菌金黃葡萄球菌細胞壁成分；
它會活化宿主的免疫系統，並誘導發炎物質的釋放。本篇論文主要是研究在
RAW 264.7 巨噬細胞中， cell Src (c-Src) 和 nicotinamide adenine dinucleotide
phosphate-dependent 氧化酶 (NADPH oxidase) 在 PGN 誘導 COX-2 的表
現中所扮演的角色。由 PGN 誘導 COX-2 的表現會被 c-Src dominant-nega
tive mutant (c-SrcDN) 、 NADPH oxidase 抑制劑 diphenyleneiodonium chlorid
e (DPI) 和抗氧化劑 glutathione (GSH) 及 N-acetylcysteine (NAC) 所抑制。 P
GN 會增加 c-Src 的磷酸化以及活化。 PGN 會時間依賴性地誘導 NADPH o
xidase 次單元 p47phox 由細胞質轉位到細胞膜上，此現象會被 c-SrcDN 所
抑制。 PGN 也會時間依賴性的增加 reactive oxygen species (ROS) 的產生，
此現象會被 DPI 、 GSH 和 NAC 所抑制。而 PGN 所誘導的 apoptosis sign
al-regulating kinase 1 (ASK1) 的活化可以被 c-SrcDN 、 DPI 、 GSH 和 NAC
所抑制。此外， PGN 誘導的 c-Jun NH2-terminal kinase 1/2 (JNK1/2) 的活化
也會被 c-SrcDN 、 GSH 和 NAC 所抑制。進一步的研究顯示， PGN 會誘
導 Toll-like receptor 2 (TLR2) 、 c-Src 以及 p47phox 複合體的產生。我們的
結果證實在 RAW 264.7 巨噬細胞中， PGN 會活化 c-Src/NADPH oxdiase 訊
號傳遞，進
而促使 ROS 的釋放，並活化下游 ASK1 與 JNK ，最終導致 COX-2 的表現
。
Involvement of c-Src and NADPH oxidase in Peptidoglycan-Induced
Cyclooxygenase-2 Expression in RAW 264.7 Macrophages
Peptidoglycan (PGN), the Gram-positive bacterium Staphylococcus aureus cell wall
component, activates the immune system of host and induces release of inflammator
y mediators. In this study, we investigated the roles of that cell c-Src (c-Src) and NA
DPH oxidase in PGN-induced cyclooxygenase-2 (COX-2) expression in RAW 264.7
macrophage. The PGN-induced COX-2 expression was attenuated by the dominant n
egative mutant of c-Src (c-SrcDN), the NADPH oxidase inhibitor diphenyleneiodoni
um chloride (DPI), and the ROS scavenger N-acetylcysteine (NAC) and glutathione
(GSH). Treatment of cells with PGN caused an increase in c-Src phosphorylation an
d c-Src activity. PGN caused a time-dependent increase in the translocation of the p4
7phox subunit of NADPH oxidase from the cytosol to the membrane fractions, whic
h was attenuated by c-SrcDN. PGN caused a time-dependent increase in reactive oxy
gen species (ROS) formation, this effect was attenuated by DPI, GSH, and NAC. Th
e PGN-induced apoptosis signal-regulating kinase 1 (ASK1) activation were inhibite
d by c-SrcDN, DPI, NAC, and GSH. Furthermore, the c-Jun NH2-terminal kinase (J
NK) activation caused by PGN was inhibited by c-SrcDN, GSH, and NAC. Further s
tudies revealed that PGN induced TLR2, c-Src, and p47phox complex formation. Ou
r results demonstrated that PGN activates the c-Src/NADPH oxdiase pathway to indu
ce ROS release, which in turn initiates the activations of ASK1 and JNK, and ultimat
ely induces COX-2 expression in RAW 264.7 macrophages.
