Coexpression of microsomal prostaglandin E synthase with cyclooxygenase-2 in human rheumatoid synovial cells.
Coexpression of microsomal prostaglandin E synthase with cyclooxygenase-2 in human rheumatoid synovial cells.
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发表时间：
2002-09
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通讯作者：
Fumiaki Kojima;H. Naraba;Y. Sasaki;R. Okamoto;T. Koshino;S. Kawai
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作者：
Fumiaki Kojima;H. Naraba;Y. Sasaki;R. Okamoto;T. Koshino;S. Kawai
目的最近克隆了微粒子前列腺素(PG)E合成酶(MPGES)，作为催化前列腺素H2合成前列腺素E2的末端酶。我们研究了类风湿关节炎(RA)患者滑膜细胞中mPGES和环氧合酶(COX)-2催化花生四烯酸生成PGH2的作用。研究地塞米松对mPGES表达的影响。方法用不同条件下的IL-1β(IL-1β)和地塞米松作用于滑膜细胞，分别用Northern印迹和Western印迹法检测mPGES的mRNA和蛋白表达。用ELISA法测定花生四烯酸或前列腺素H_2向前列腺素E_2的转化率。免疫荧光显微镜分析mPGES和COX-2的亚细胞定位。结果IL-1β可显著上调滑膜细胞mPGES基因和蛋白的表达。IL-1β对COX-2mRNA和蛋白也有上调作用，但与mPGES的作用时程不同。IL-1β促进PGH2向PGE2的转化，并与mPGES的表达相关。当mPGES和COX-2共表达时，花生四烯酸向PGE2的转化率保持增加。在IL-1β刺激的滑膜细胞中，mPGES和COX-2在核周的亚细胞定位重叠。地塞米松抑制IL-1β刺激的细胞mPGES的表达，促进花生四烯酸向PGE2的转化，但对mPGES的抑制作用弱于COX-2。结论类风湿滑膜等炎症部位大量产生PGE2是由mPGES和COX-2协同上调所致。因此，mPGES可能成为控制PGE2合成的治疗策略的潜在新靶点，特别是在RA和其他炎症性疾病患者中。
OBJECTIVE Recently, microsomal prostaglandin (PG) E synthase (mPGES) was cloned as a terminal enzyme catalyzing PGH2 to PGE2. We investigated mPGES as well as cyclooxygenase (COX)-2, catalyzing arachidonic acid to PGH2, in synovial cells from patients with rheumatoid arthritis (RA). The effect of dexamethasone on mPGES expression was also studied. METHODS Synovial cells were treated with interleukin 1beta (IL-1beta) and dexamethasone under various conditions, and expression of mPGES mRNA and protein was analyzed by Northern blot and Western blot, respectively. Conversions of arachidonic acid or PGH2 to PGE2 were measured by ELISA. Subcellular localization of mPGES and COX-2 was determined by immunofluorescent microscopic analysis. RESULTS mPGES mRNA and protein expression were significantly upregulated by IL-1beta in synovial cells. COX-2 mRNA and protein were also upregulated by IL-1beta, but with a different time course from that of mPGES. Conversion of PGH2 to PGE2 increased by IL-1beta and was correlated with mPGES expression. Increased conversion of arachidonic acid to PGE2 was maintained when mPGES and COX-2 were coexpressed. Subcellular localization of mPGES and COX-2 overlapped in the perinuclear region in IL-1beta stimulated synovial cells. Dexamethasone inhibited mRNA and protein expression for mPGES and increased conversion of arachidonic acid to PGE2, but inhibition of mPGES was weaker compared with that of COX-2 in IL-1beta stimulated cells. CONCLUSION The results suggest that abundant PGE2 production at inflammation sites such as rheumatoid synovia is caused by the coordinated upregulation of mPGES and COX-2. Thus mPGES might be a potential new target for therapeutic strategies to control PGE2 synthesis specifically in patients with RA and other inflammatory diseases.