Study on the function of receptor for Helicobacter pylori VacA and the mechanism of its intoxication

幽门螺杆菌VacA受体功能及其中毒机制研究

基本信息

批准号：
17209015
负责人：
HIRAYAMA Toshiya
金额：
$ 32.03万
依托单位：
Nagasaki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17209015/
关键词：
Helicobacter pylori VacA AZ-521 cells COX-2 PGE_2 p38 MAP kinase ATF-2 cascade Bacterial toxin Pathogenesis

项目摘要

By 2006 budget, we found that VacA increases PGE_2 production by AZ-521 cells by up-regulation of COX-2 expression through a signaling pathway involving the p38 MAP kinase/ATF-2 cascade, leading to activation of the CRE element on the COX-2 promoter.Treatment of AZ-521 cells with Helicobacter pylori VacA increased cyclooxygenase-2 (COX-2) mRNA in a time-and dose-dependent manner. A p38 MAP kinase (MAPK) inhibitor, SB203580, blocked elevation of COX-2 mRNA levels, whereas PD98059, which blocks the Erkl/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 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-kB or NF-IL6 sites, but not a mutated CRE site, suggesting direct involvement of the 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-siRNA resulted in suppression of COX-2 expression. Thus, we found that VacA enhances PGE_2 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.

到 2006 年预算，我们发现 VacA 通过涉及 p38 MAP 激酶/ATF-2 级联的信号通路上调 COX-2 表达，从而增加 AZ-521 细胞的 PGE_2 产量，从而激活 COX 上的 CRE 元件-2 启动子。用幽门螺杆菌 VacA 处理 AZ-521 细胞可在一段时间内增加环氧合酶-2 (COX-2) mRNA剂量依赖性方式。 p38 MAP 激酶 (MAPK) 抑制剂 SB203580 阻断 COX-2 mRNA 水平的升高，而阻断 Erk1/2 级联的 PD98059 部分抑制这种升高。与 p38 MAPK 的参与一致，在过表达显性失活 p38 MAPK (DN-p38) 的 AZ-521 细胞中，VacA 诱导的 COX-2 mRNA 积累减少。磷脂酰肌醇特异性磷脂酶 C 可抑制 VacA 诱导的 p38 MAPK 激活，并阻断 VacA 诱导的 COX-2 表达。与 COX-2 表达同时，VacA 增加 PGE_2 的产生，而 PGE_2 的产生被 SB203580 和 COX-2 抑制剂 NS-398 抑制。在稳定表达 DN-p38 的 AZ-521 细胞中，VacA 诱导的 PGE2 产生显着减弱。 VacA 增加 COX-2 启动子报告基因的转录，并激活包含突变 NF-kB 或 NF-IL6 位点的 COX-2 启动子，但不激活突变 CRE 位点，表明 ATF-2/CREB 结合区直接参与VacA 诱导 COX-2 启动子激活。用 ATF-2-siRNA 转化的 AZ-521 细胞中 ATF-2 表达的减少导致 COX-2 表达的抑制。因此，我们发现 VacA 通过 p38 MAPK /ATF-2 级联诱导 COX-2 表达，从而激活 COX-2 启动子中的 CRE 位点，从而增强 AZ-521 细胞的 PGE_2 产生。