幽门螺杆菌cagA基因多态性对临床结局的影响：东亚菌株和西方菌株

CagA蛋白是幽门螺杆菌最重要的毒力因子之一。目前已证实cagA基因存在东亚及西方两种亚型。幽门螺杆菌产生CagA蛋白,注入胃上皮细胞后在其羧基端EPIYA重复序列区进行酪氨酸磷酸化,进而与SHP-2酪氨酸磷酸化酶相互作用,参与上皮细胞的信号传导,导致细胞骨架结构的重排,引起细胞表面形状的改变和细胞动力的增强,造成细胞异常的增殖和运动,在胃癌的发生中起了主要作用。cagA基因的羧基端EPIYA重复序列被认为是区分东亚型和西方型菌株的分子标记,东亚型CagA与SHP-2亲和力大于西方型,最终影响着不同CagA 菌株感染的临床表现。

Influence of Helicobacter Pylori CagA Gene Polymorphism on Clinical Outcome:East Asia type strain and Western type strain

CagA protein is one of the virulence factors of Helicobacter pylori, and two major subtypes of cagA strains have been observed, the Western and East Asian types. When CagA is injected from the bacteria into gastric epithelial cell, it undergoes tyrosine phosphorylation at the EPIYA-repeat region, which is regarded as the molecular marker for distinguishing the East Asian and Western type strains, and then it binds to Src homology 2 domain-containing protein-tyrosine phosphatase SHP-2, thereby induces an elongated cell shape known as the hummingbird phenotype. The East Asian type CagA binds to SHP-2 more strongly than the Western type CagA. The diversity of CagA, which collectively determines the binding affinity of CagA to SHP-2, may be an important variable in determining the clinical outcome of infection by different cagA Helicobacter pylori strains.