Helicobacter pylori VacA enhances prostaglandin E2 production through induction of cyclooxygenase 2 expression via a p38 mitogen-activated protein Kinase/Activating transcription factor 2 cascade in AZ-521 cells
Helicobacter pylori VacA enhances prostaglandin E2 production through induction of cyclooxygenase 2 expression via a p38 mitogen-activated protein Kinase/Activating transcription factor 2 cascade in AZ-521 cells
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DOI：
10.1128/iai.00500-07
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发表时间：
2007-09-01
影响因子：
3.1
通讯作者：
Hirayama, Toshiya
中科院分区：
文献类型：
--
作者：
Hisatsune, Junzo;Yamasaki, Eiki;Hirayama, Toshiya
幽门螺杆菌VacA处理AZ-521细胞后，环氧合酶2（考克斯-2）mRNA表达呈时间和剂量依赖性增加。p38丝裂原活化蛋白激酶（MAPK）抑制剂SB 203580可阻断考克斯-2 mRNA水平的升高，而阻断Erk 1/2级联反应的PD 98059可部分抑制这种升高。与p38 MAPK的参与一致，在过表达显性阴性p38 MAPK（DN-p38）的AZ-521细胞中，VacA诱导的考克斯-2 mRNA的积累减少。磷脂酰肌醇特异性磷脂酶C抑制VacA诱导的p38 MAPK活化，阻断VacA诱导的考克斯-2表达。与考克斯-2表达平行，VacA增加前列腺素E-2（PGE（2））的产生，这被SB 203580和NS-398（一种考克斯-2抑制剂）抑制。在稳定表达DN-p38的AZ-521细胞中，VacA诱导的PGE 2产生显著减弱。VacA增加了考克斯-2启动子报告基因的转录，并激活了含有突变的NF-κ B或NF-白细胞介素-6位点但不含突变的顺式作用复制元件（CRE）位点的考克斯-2启动子，表明活化转录因子2（ATF-2）/CREB结合区直接参与了VacA诱导的考克斯-2启动子激活。ATF-2-small interfering RNA双链体转染AZ-521细胞后，ATF-2表达降低，考克斯-2表达受到抑制。因此，VacA通过经由p38 MAPK/ATF-2级联诱导考克斯-2表达，导致考克斯-2启动子中的CRE位点活化，从而增强AZ-521细胞的PGE 2产生。
Treatment of AZ-521 cells with Helicobacter pylori VacA increased cyclooxygenase 2 (COX-2) mRNA in a time- and dose-dependent manner. A p38 mitogen-activated protein kinase (MAPK) inhibitor, SB203580, blocked elevation of COX-2 mRNA levels, whereas PD98059, which blocks the Erk1/2 cascade, partially suppressed the increase. Consistent with involvement of p38 MAPK,, VacA-induced accumulation of COX-2 mRNA was reduced in AZ-521 cells overexpressing a dominant-negative p38 MAPK (DN-p38). Phosphatidylinositol-specific phospholipase C, which inhibits VacA-induced p38 MAPK activation, blocked VacA-induced COX-2 expression. In parallel with COX-2 expression, VacA increased prostaglandin E-2 (PGE(2)) production, which was inhibited by SB203580 and NS-398, a COX-2 inhibitor. VacA-induced PGE2 Production was markedly attenuated in AZ-521 cells stably expressing DN-p38. VacA increased transcription of a COX-2 promoter reporter gene and activated a COX-2 promoter containing mutated NF-kappa B or NF-interieukin-6 sites but not a mutated cis-acting replication element (CRE) site, suggesting direct involvement of the activating transcription factor 2 (ATF-2)/CREB-binding region in VacA-induced COX-2 promoter activation. The reduction of ATF-2 expression in AZ-521 cells transformed with ATF-2-small interfering RNA duplexes resulted in suppression of COX-2 expression. Thus, VacA enhances PGE2 production by AZ-521 cells through induction of COX-2 expression via the p38 MAPK/ATF-2 cascade, leading to activation of the CRE site in the COX-2 promoter.