Determinants and consequences of different levels of CagA phosphorylation for clinical isolates of Helicobacter pylori
Determinants and consequences of different levels of CagA phosphorylation for clinical isolates of Helicobacter pylori
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DOI：
10.1053/j.gastro.2004.06.006
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发表时间：
2004-08-01
期刊：
影响因子：
29.4
通讯作者：
Atherton, JC
中科院分区：
文献类型：
--
作者：
Argent, RH;Kidd, M;Atherton, JC
背景和目标：幽门螺杆菌cag致病岛编码一个分泌系统，该系统将CagA易位到上皮细胞中，在上皮细胞中CagA变得酪氨酸磷酸化并诱导细胞骨架重排。具有更多CagA酪氨酸磷酸化基序的菌株与胃癌关系最密切。在这里，我们评估临床菌株是否可以提供CagA，是否具有不同数量的CagA磷酸化基序的菌株具有不同程度的CagA磷酸化，以及这是否诱导不同数量的上皮细胞骨架变化。将cagA基因阳性的南非患者的pylori菌株与胃腺癌细胞系AGS共培养。CagA表达和磷酸化通过Western印迹和interukin-8分泌通过酶联免疫吸附试验测定。对22株cagA基因3'端可变区进行了序列测定，结果显示有3-6个磷酸化基序。结果：cagA基因型和cag致病岛基因分型对表型的预测性较差。44个菌株中有34个表达CagA蛋白，该蛋白可以被递送到AGS细胞内并在AGS细胞内磷酸化。只有这34株菌株诱导AGS细胞分泌白细胞介素-8。在这些菌株中，CagA酪氨酸磷酸化基序的数量决定了CagA磷酸化的程度和AGS细胞伸长的程度和范围方面的生物活性水平。递送具有更多磷酸化基序的CagA的幽门螺杆菌菌株在上皮细胞中诱导更高水平的CagA磷酸化，诱导更多的细胞骨架变化，并且更可能与胃癌相关。
Background & Aims: The Helicobacter pylori cag pathogenicity island encodes a secretory system that translocates CagA into epithelial cells, where it becomes tyrosine phosphorylated and induces cytoskeletal rearrangements. Strains with more CagA tyrosine phosphorylation motifs are most closely associated with gastric cancer. Here we assess whether clinical strains can deliver CagA, whether strains with different numbers of CagA phosphorylation motifs have CagA phosphorylated to different degrees, and whether this induces different amounts of epithelial cytoskeletal change.Methods: Forty-four H. pylori strains from South African patients, all cagA gene positive, were cocultured with the gastric adenocarcinoma cell line AGS. CagA expression and phosphorylation were determined by Western blot and intereukin-8 secretion by enzyme-linked immunosorbent assay. The cagA 3' variable regions of 22 strains were sequenced and shown to possess 3-6 phosphorylation motifs. These strains were used to quantify CagA phosphorylation and cytoskeletal rearrangements.Results: cagA genotype and typing of cag pathogenicity island genes were poorly predictive of phenotype. Thirty-four of 44 strains expressed CagA protein that could be delivered to and phosphorylated within AGS cells. Only these 34 strains induced interleukin-8 secretion from AGS cells. Among those strains, the number of CagA tyrosine phosphorylation motifs determined the degree of CagA phosphorylation and the level of biologic activity in terms of degree and extent of AGS cell elongation.Conclusions: H. pylori strains that deliver CagA with more phosphorylation motifs induce higher levels of CagA phosphorylation in epithelial cells, induce more cytoskeletal changes, and are more likely to be associated with gastric cancer.