胃癌是全球第三大常见恶性肿瘤,主要由幽门螺杆菌感染、遗传因素和环境因素诱发,其中幽门螺杆菌感染是最重要危险因素之一。细胞毒素相关蛋白A(cytotoxin-associated protein A,CagA)是幽门螺杆菌中重要的毒力因子,其蛋白羧基末端谷氨酸...胃癌是全球第三大常见恶性肿瘤,主要由幽门螺杆菌感染、遗传因素和环境因素诱发,其中幽门螺杆菌感染是最重要危险因素之一。细胞毒素相关蛋白A(cytotoxin-associated protein A,CagA)是幽门螺杆菌中重要的毒力因子,其蛋白羧基末端谷氨酸-脯氨酸-异亮氨酸-酪氨酸-丙氨酸基序(Glu-Pro-Ile-Tyr-Ala,EPIYA)包含多个重复序列单元,其数量和排列方式会导致CagA蛋白的功能差异。该区域也是酪氨酸磷酸化的主要结合位点,能够参与多种信号通路影响胃癌的发生。本文通过概述CagA EPIYA多态性参与的Wnt/β-catenin、MAPK和PI3K/Akt关键信号通路,探讨CagA EPIYA多态性诱导宿主细胞的重要信号蛋白异常表达,激活信号通路效应差异,从而进一步明确CagA EPIYA多态性在胃癌发生机制中的作用,为控制幽门螺杆菌感染及精准治疗胃癌靶点提供新思路和新策略。展开更多
BACKGROUND Helicobacter pylori(H.pylori)colonizes the human stomach and is a major cause of peptic ulcer disease and gastric cancer.However,although the prevalence of H.pylori is high in Africa,the incidence of gastri...BACKGROUND Helicobacter pylori(H.pylori)colonizes the human stomach and is a major cause of peptic ulcer disease and gastric cancer.However,although the prevalence of H.pylori is high in Africa,the incidence of gastric cancer is low,and this phenomenon is called to be African enigma.The CagA protein produced by H.pylori is the most studied virulence factor.The carcinogenic potential of CagA is associated with the Glu-Pro-Ile-Tyr-Ala(EPIYA)patterns and CagAmultimerization(CM)motifs.AIM To better understand the EPIYA patterns and CM motifs of the cagA gene.METHODS Gastric mucosal biopsy specimens were obtained from 258 patients with dyspepsia living in the Dominican Republic,from which 120 H.pylori strains were cultured.After the bacterial DNA extraction,the EPIYA pattern and CM motif genotypes were determined using a polymerase chain reaction-based sequencing.The population structure of the Dominican Republic strains was analyzed using multilocus sequence typing(MLST).Peptic ulcer disease and gastric cancer were identified via endoscopy,and gastric cancer was confirmed by histopathology.Histological scores of the gastric mucosa were evaluated using the updated Sydney system.RESULTS All CagA-positive strains carried the Western-type CagA according to the identified EPIYA patterns.Twenty-seven kinds of CM motifs were observed.Although the typical Western CM motif(FPLKRHDKVDDLSKVG)was observed most frequently,the typical East Asian CM motif(FPLRRSAAVNDLSKVG)was not observed.However,“FPLRRSAKVEDLSKVG”,similar to the typical East Asian CM motif,was found in 21 strains.Since this type was significantly more frequent in strains classified as hpAfrica1 using MLST analysis(P=0.034),we termed it Africa1-CM(Af1-CM).A few hpEurope strains carried the Af1-CM motif,but they had a significantly higher ancestral Africa1 component than that of those without the Af1-CM motif(P=0.030).In 30 cagA-positive strains,the"GKDKGPE"motif was observed immediately upstream of the EPIYA motif in the EPIYA-A segment,and there was a significant association between strains with the hpAfrica1 population and those containing the“GKDKGPE”motif(P=0.018).In contrast,there was no significant association between the CM motif patterns and histological scores and clinical outcomes.CONCLUSION We found the unique African CM motif in Western-type CagA and termed it Africa1-CM.The less toxicity of this motif could be one reason to explain the African enigma.展开更多
Objective To investigate whether the presence of structured CagA proteins in Western- and Eastern-type Helicobacter pylori （H. pylori） induces different incidences of gastric diseases. Methods CagA and phosphorylatd...Objective To investigate whether the presence of structured CagA proteins in Western- and Eastern-type Helicobacter pylori （H. pylori） induces different incidences of gastric diseases. Methods CagA and phosphorylatd CagA were expressed in AGS gastric epithelial cells infected with wild type and mutant strains. The ability of individual CagA was determined by immunoprecipitation and Western blot assay. Morphological changes of these cells were observed under microscope to evaluate the appearance of elongation hummingbird phenotype. Results The sizes of CagA proteins in different strains were different, and no phosphorylated CagA proteins were detected in wild-type strains. Meanwhile, the kinetics of CagA status in AGS infected with H. pylori was detected. The molecular weight of phosphorylated CagA with the same size of CagA proteins in H. pylori was different in infections with different wild-type strains. CagA and phosphorylated CagA increased in a time-dependent manner after the infection. The hummingbird phenotype with H. pylori for time-course was observed under microscope. Instead of HPK5 strain, the wild-type 26695 strain induced hummingbird phenotype in a time-dependent manner. Conclusion Translocation and phosphorylation of CagA are necessary, but not sufficient, for the induction of hummingbird phenotype in AGS cells.展开更多
基金Supported by The Grants-in-aid for Scientific Research from the Ministry of Education,Culture,Sports,Science,and Technology of Japan,No.16H05191,No.221S0002,No.16H06279,No.18KK0266 and No.19H03473(partly)the National Fund for Innovation and Development of Science and Technology from the Ministry of Higher Education Science and Technology of the Dominican Republic,No.2012-2013-2A1-65 and No.2015-3A1-182(MC).
文摘BACKGROUND Helicobacter pylori(H.pylori)colonizes the human stomach and is a major cause of peptic ulcer disease and gastric cancer.However,although the prevalence of H.pylori is high in Africa,the incidence of gastric cancer is low,and this phenomenon is called to be African enigma.The CagA protein produced by H.pylori is the most studied virulence factor.The carcinogenic potential of CagA is associated with the Glu-Pro-Ile-Tyr-Ala(EPIYA)patterns and CagAmultimerization(CM)motifs.AIM To better understand the EPIYA patterns and CM motifs of the cagA gene.METHODS Gastric mucosal biopsy specimens were obtained from 258 patients with dyspepsia living in the Dominican Republic,from which 120 H.pylori strains were cultured.After the bacterial DNA extraction,the EPIYA pattern and CM motif genotypes were determined using a polymerase chain reaction-based sequencing.The population structure of the Dominican Republic strains was analyzed using multilocus sequence typing(MLST).Peptic ulcer disease and gastric cancer were identified via endoscopy,and gastric cancer was confirmed by histopathology.Histological scores of the gastric mucosa were evaluated using the updated Sydney system.RESULTS All CagA-positive strains carried the Western-type CagA according to the identified EPIYA patterns.Twenty-seven kinds of CM motifs were observed.Although the typical Western CM motif(FPLKRHDKVDDLSKVG)was observed most frequently,the typical East Asian CM motif(FPLRRSAAVNDLSKVG)was not observed.However,“FPLRRSAKVEDLSKVG”,similar to the typical East Asian CM motif,was found in 21 strains.Since this type was significantly more frequent in strains classified as hpAfrica1 using MLST analysis(P=0.034),we termed it Africa1-CM(Af1-CM).A few hpEurope strains carried the Af1-CM motif,but they had a significantly higher ancestral Africa1 component than that of those without the Af1-CM motif(P=0.030).In 30 cagA-positive strains,the"GKDKGPE"motif was observed immediately upstream of the EPIYA motif in the EPIYA-A segment,and there was a significant association between strains with the hpAfrica1 population and those containing the“GKDKGPE”motif(P=0.018).In contrast,there was no significant association between the CM motif patterns and histological scores and clinical outcomes.CONCLUSION We found the unique African CM motif in Western-type CagA and termed it Africa1-CM.The less toxicity of this motif could be one reason to explain the African enigma.
基金supported by China Postdoctoral Science Foundation (Grant No. 20070420277)
文摘Objective To investigate whether the presence of structured CagA proteins in Western- and Eastern-type Helicobacter pylori （H. pylori） induces different incidences of gastric diseases. Methods CagA and phosphorylatd CagA were expressed in AGS gastric epithelial cells infected with wild type and mutant strains. The ability of individual CagA was determined by immunoprecipitation and Western blot assay. Morphological changes of these cells were observed under microscope to evaluate the appearance of elongation hummingbird phenotype. Results The sizes of CagA proteins in different strains were different, and no phosphorylated CagA proteins were detected in wild-type strains. Meanwhile, the kinetics of CagA status in AGS infected with H. pylori was detected. The molecular weight of phosphorylated CagA with the same size of CagA proteins in H. pylori was different in infections with different wild-type strains. CagA and phosphorylated CagA increased in a time-dependent manner after the infection. The hummingbird phenotype with H. pylori for time-course was observed under microscope. Instead of HPK5 strain, the wild-type 26695 strain induced hummingbird phenotype in a time-dependent manner. Conclusion Translocation and phosphorylation of CagA are necessary, but not sufficient, for the induction of hummingbird phenotype in AGS cells.
