A transgenic Drosophila model demonstrates that the Helicobacter pylori CagA protein functions as a eukaryotic Gab adaptor
A transgenic Drosophila model demonstrates that the Helicobacter pylori CagA protein functions as a eukaryotic Gab adaptor
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DOI：
10.1371/journal.ppat.1000064
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发表时间：
2008-05-01
期刊：
影响因子：
6.7
通讯作者：
Guillemin, Karen
中科院分区：
文献类型：
--
作者：
Botham, Crystal M.;Wandler, Anica M.;Guillemin, Karen
人类胃病原体幽门螺杆菌的感染与一系列疾病有关，包括胃炎、消化性溃疡、胃腺癌和胃粘膜相关淋巴组织淋巴瘤。幽门螺杆菌的细胞毒素相关基因A(CagA)蛋白通过IV型分泌系统转运到宿主细胞中，是疾病发生的主要危险因素。在胃组织培养细胞中的实验表明，一旦移位，CagA就会激活磷酸酶SHP-2，这是受体酪氨酸激酶(RTK)途径的一个组成部分，其过度激活与癌症的形成有关。基于CagA激活SHP-2的能力，有人提出CagA的功能是真核细胞中Grb2相关结合蛋白(Gab)接头蛋白的原核模拟，后者通常激活SHP-2。我们已经开发了一个转基因果蝇模型来验证这一假设，方法是研究CagA是否在一个具有良好特征的依赖于Gab的过程中发挥作用：果蝇眼睛中光感受器细胞的指定。我们证明，CagA的表达足以挽救光感受器的发育，在缺乏果蝇Gab同源物的情况下，Seven less(DOS)的女儿。此外，CagA促进光感受器发育的能力需要SHP-2磷酸酶开瓶器(CSW)。这些结果首次证明了CagA在生物体组织中作为一种Gab蛋白发挥作用，并为深入了解CagA的致癌潜力提供了线索。由于许多转位的细菌蛋白针对高度保守的真核细胞过程，如RTK信号通路，转基因果蝇模型应该可以普遍用于检测细菌效应蛋白的体内功能，并用于鉴定它们发挥作用的宿主基因。
Infection with the human gastric pathogen Helicobacter pylori is associated with a spectrum of diseases including gastritis, peptic ulcers, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. The cytotoxin- associated gene A (CagA) protein of H. pylori, which is translocated into host cells via a type IV secretion system, is a major risk factor for disease development. Experiments in gastric tissue culture cells have shown that once translocated, CagA activates the phosphatase SHP-2, which is a component of receptor tyrosine kinase (RTK) pathways whose over-activation is associated with cancer formation. Based on CagA's ability to activate SHP-2, it has been proposed that CagA functions as a prokaryotic mimic of the eukaryotic Grb2-associated binder (Gab) adaptor protein, which normally activates SHP-2. We have developed a transgenic Drosophila model to test this hypothesis by investigating whether CagA can function in a well-characterized Gab-dependent process: the specification of photoreceptors cells in the Drosophila eye. We demonstrate that CagA expression is sufficient to rescue photoreceptor development in the absence of the Drosophila Gab homologue, Daughter of Sevenless (DOS). Furthermore, CagA's ability to promote photoreceptor development requires the SHP-2 phosphatase Corkscrew (CSW). These results provide the first demonstration that CagA functions as a Gab protein within the tissue of an organism and provide insight into CagA's oncogenic potential. Since many translocated bacterial proteins target highly conserved eukaryotic cellular processes, such as the RTK signaling pathway, the transgenic Drosophila model should be of general use for testing the in vivo function of bacterial effector proteins and for identifying the host genes through which they function.