| Summary: | 碩士 === 臺北醫學大學 === 藥理學研究所 === 92 === Peptidoglycan (PGN), a cell wall component of Gram-positive bacteria,can induce multiple similar responses in immune system as same as lipopolysaccharide (LPS) which is well known as a main cell wall component of Gram-negative bacteria caused inflammations. Our previous study shown that PGN induced cyclooxygenase-2 (COX-2) expression via Ras/Raf-1/ERK and NF-B signaling pathway in RAW 264.7 macrophages (J. Biol. Chem., 279:20889-20897, 2004). In this study, we investigated the roles of Ras/PI3K/Akt and p38MAPK/MSK1 on PGN-induced COX-2 expression in RAW 264.7 macrophages. PGN-induced COX-2 expression was inhibited by specific inhibitors of PI3K (wortmannin and LY294002), Ras inhibitor (manumycin A), Akt inh. (1L-6-Hydroxymethylchiro-inositol-2[(R)-2-O-methyl-3-O-octadecylcarbonate], p38 MAPK inhibitor (SB 203580) and MSK1 inhibitor (Ro 318220). Moreover, PGN induced IKK alpha/beta, p38 MAPK and MSK1 activity and increases in phosphorylation of Akt Ser473, p65 Ser536 and Ser276 in a time-depenednt manner. PGN induced increases in phosphorylation of Akt Ser473 and IKK alpha/beta on PGN-induced was inhibited by manumycin A, LY 294002 and Akt inh.. However, manumycin A, LY 294002 and Akt inh. did not inhibit PGN-induced p65 Ser536 phosphorylation. Inversely,PGN-induced p65 Ser276 phosphorylation was reduced by SB 203580 and Ro 318220 in RAW 264.7 macrophages. Moreover, PGN-induced kB-luciferase activity was inhibited by wortmannin, LY 294002, Akt inh., SB 203580 and Ro 318220. Further studies reveals that PGN induced the recruitment of p85 alpha and Ras to Toll-like receptor 2 (TLR2) in time-dependent manner. This propose demonstrate that two pathway
cross-link between Ras/PI3k/Akt and p38 MAPK/MSK1 to induce
IKK alpha/beta activity, p65 Ser536 and Ser276 phosphorylation and NF-kB activation, respectively and ultimately induce COX-2 expression in RAW 264.7 macrophages.
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