幽门螺杆菌IV型分泌系统效应蛋白的鉴定及其功能的研究

It is estimated that Helicobacter pylori (H. pylori) colonize the stomachs of over 50% of the population globally. H. pylori infection can lead to chronic gastritis in humans, and 10–15% of infected people may develop severe gastric diseases and even cancer. Virulent H. pylori strains carry a cytotoxin-associated gene-pathogenicity island (cag PAI), which encodes a type IV secretion system (T4SS). The cytotoxin-associated gene A (CagA) is the only known protein effector that is translocated into the infected host cell via the T4SS. Studies have revealed that CagA is involved in the development of gastric adenocarcinomas. Another major virulence factor is the vacuolating toxin A (VacA). VacA is best known for inducing vacuoles within epithelial cell, and it also inhibits T lymphocyte proliferation and modulates T cell function. In addition to CagA- and VacA-mediated virulence properties, H. pylori induce additional host responses that require a functional T4SS. We hypothesize that additional T4SS effectors might be responsible for these activities in H. pylori. As shown in our preliminary data, we have developed biochemical and cellular assays to identify new T4SS effectors in H. pylori. In this proposal, we plan to 1) Identify and validate type IV effectors in H. pylori; 2) Assess the phenotypes of the effector mutants and their roles in inflammation during H. pylori infection. New effectors identified from our study may open up new research fronts in H. pylori to better understand how H. pylori induces ulcer and even cancer during infection.

幽门螺杆菌在人群中的感染非常普遍，该菌是慢性胃炎的病原体，且与消化性溃疡和胃癌的发生密切相关，构成对人类健康的重大威胁，WHO已将其确定为I类致癌因子。幽门螺杆菌强毒株携带一个编码IV型分泌系统(T4SS)的致病岛，对细菌致病性至关重要。细胞毒素相关蛋白A (CagA)是迄今唯一确定通过T4SS从幽门螺杆菌移位到宿主细胞的效应蛋白，但众多研究显示除CagA外，更多T4SS效应蛋白参与了幽门螺杆菌的致病过程。令人遗憾的是由于受到检测方法的制约，相应蛋白的鉴定和功能研究长期无法实施。申请人团队历经数年探索已经成功建立了鉴定幽门螺杆菌T4SS效应蛋白的生化和细胞分析方法。在此基础上，本项目计划 1)鉴定幽门螺杆菌的IV型分泌系统效应蛋白；2)分析在幽门螺杆菌感染过程中这些效应蛋白突变体的表型及其在炎症中的作用。本项目可极大促进对幽门螺杆菌毒力机制的基础科学研究，且可为临床药物研发提供依据。

幽门螺杆菌在人群中的感染非常普遍，该菌是慢性胃炎的病原体，且与消化性溃疡和胃癌的发生密切相关，对人类健康构成重大威胁。幽门螺杆菌强毒株携带一个编码IV型分泌系统(T4SS)的致病岛，对细菌致病性至关重要。细胞毒素相关蛋白A（CagA）是目前唯一确定通过T4SS从幽门螺杆菌移位到宿主细胞的效应蛋白。但众多研究表明除CagA外，还存在潜在的T4SS效应蛋白参与幽门螺杆菌的致病过程。本项目利用质谱技术鉴定到了14种分泌蛋白，并通过TEM1转位实验证实了HP0367是依赖于T4SS分泌的效应蛋白。随后的细胞因子分泌检测表明HP0367可能涉及巨噬细胞炎症反应。效应蛋白也可以通过翻译后修饰宿主蛋白，介导胞内多种信号通路；本项目还进行了幽门螺杆菌感染宿主的磷酸化蛋白组学分析，可促进对效应蛋白的作用机制的研究。综上，本项目有助于深入解幽门螺杆菌的致病性机制，可为未来药物开发提供潜在分子靶标和科学依据。