Activation of Abl by Helicobacter pylori:: A novel kinase for CagA and crucial mediator of host cell scattering
Activation of Abl by Helicobacter pylori:: A novel kinase for CagA and crucial mediator of host cell scattering
复制标题
DOI：
10.1053/j.gastro.2007.01.050
复制
发表时间：
2007-04-01
期刊：
影响因子：
29.4
通讯作者：
Backert, Steffen
中科院分区：
文献类型：
--
作者：
Tammer, Ina;Brandt, Sabine;Backert, Steffen
背景与目的：幽门螺杆菌（Helicobacter pylori，Hp）相关性疾病的发病机制依赖于一种特殊的IV型分泌系统.这种IV型分泌系统将细胞毒素相关基因A（CagA）效应蛋白注射到靶细胞中，其中CagA在酪氨酸残基上被Src磷酸化。然后Src迅速失活，表明存在另一种宿主酪氨酸激酶，以确保在持续的Hp感染中恒定的CagA磷酸化。我们的目标是鉴定这种激酶。研究方法：通过使用AGS胃上皮细胞模型，我们进行了详细的功能特性的Abl酪氨酸激酶的信号在幽门螺杆菌感染。结果：我们发现Abl激酶被激活，并且是Hp感染的一种新的关键介质。首先，CagA特异性抑制剂SKI-DV 2 -43或STI 571（Gleevec，Novartis）和通过小发夹和干扰RNA敲低c-Abl/CagA相关基因Arg有效地抑制CagA磷酸化和细胞分散。其次，在感染过程中，Abl通过Y-412处的自磷酸化而被迅速激活。第三，Abl和Src均磷酸化CagA的Y-899、Y-918和Y-972。第四，我们发现Abl底物CrkII在体内在Y-221处被磷酸化。第五，激酶死亡Abl（K290 M）的过表达阻断了Hp诱导的肌动蛋白细胞骨架重排。我们进一步表明，维持CagA磷酸化需要Abl的持续活性。状态此外，磷酸化的CagA在体内与Abl和活化的CrkII形成物理复合物。结论：我们提出了一个模型，其中Hp已经进化出一种机制，使用至少2种酪氨酸激酶，Src和Src，用于CagA磷酸化和随后的肌动蛋白-细胞骨架重排，导致细胞分散和延伸。
Background & Aims: The pathogenesis of Helicobacter pylori (Hp)-associated diseases depends on a specialized type IV secretion system. This type IV secretion system injects the cytotoxin-associated gene A (CagA) effector protein into target cells where CagA becomes phosphorylated on tyrosine residues by Src. Src then is inactivated rapidly, suggesting the presence of another host tyrosine kinase to ensure constant CagA phosphorylation in sustained Hp infections. We aimed to identify this kinase. Methods: By using the AGS gastric epithelial Cell model, we performed a detailed functional characterization of Abl tyrosine kinase in signaling during Hp infections. Results: We showed that Abl kinase is activated and a novel crucial mediator of Hp infections. First, Abl-specific inhibitors SKI-DV2-43 or STI571 (Gleevec, Novartis) and knockdown of c-Abl/Abl-related gene Arg by small hairpin and interfering RNAs efficiently inhibit CagA phosphorylation and cell scattering. Second, during infection, Abl is activated rapidly by autophosphorylation at Y-412. Third, both Abl and Src phosphorylated Y-899, Y-918, and Y-972 of CagA. Fourth, we found that the Abl substrate CrkII is phosphorylated at Y-221 in vivo. Fifth, overexpression of kinase-dead Abl (K290M) blocked Hp-induced actin cytoskeletal rearrangements. We further showed that sustained activity of Abl is required to maintain CagA in a phosphorylated. state. Moreover, phosphorylated CagA forms a physical complex with Abl and activated CrkII in vivo. Conclusions: we propose a model in which Hp has evolved a mechanism to use at least 2 tyrosine kinases, Abl. and Src, for CagA phosphorylation and subsequent actin-cytoskeletal rearrangements leading to cell scattering and elongation.