幽门螺杆菌CagA对AGS细胞RNA转录相关磷酸化蛋白的影响

目的研究幽门螺杆菌（Helicobacter pylori，H.pylori）细胞毒素相关蛋白A（CagA）作用后人胃腺癌上皮细胞（AGS）RNA转录相关蛋白磷酸化的变化情况，进一步揭示CagA的致病机制，为寻找生物标记蛋白奠定基础。方法采用金属离子亲和吸附富集技术富集H.pylori、H.pylori CagA缺失株（H.pylori△CagA）与AGS细胞相互作用4h、以及培养相同时间的AGS细胞的磷酸化蛋白，利用二维凝胶电泳技术分离磷酸化蛋门，ImageMaster 2D分析软件比较分析识别差异蛋白，4700型MALDI源蛋白分析器确认蛋白。结果CagA致使AGS细胞的7个RNA相关的磷酸化蛋白出现差异表达，其中1个磷酸化蛋白表达量上调、4个磷酸化蛋白表达量下调、2个新出现磷酸化的蛋白。hnRNP D0 127位的苏氨酸及137位的丝氨酸发生了磷酸化。结论CagA作用后，致使hnRNP D0蛋白磷酸化。AGS细胞与RNA转录相天蛋白磷酸化的变化，呈现出诱导细胞凋亡、增殖及有利于细胞免疫逃逸的趋势。     

CagA+Hp感染与消化性溃疡

目的本文旨在探讨十二指肠球部溃疡、胃溃疡等与产细胞毒相关蛋白A幽门螺旋杆菌(CagA+Hp)感染的关系.方法分为三组即无症状对照组、十二指肠球部溃疡及胃溃疡组,Hp感染以快速尿素酶试验(RUT)、14C-呼气试验(14C-URT)和(或)病理特殊染色确定,CagA+Hp感染则进一步通过检测血清CagA IgG加以确定.分别计算各组Hp及CagA+Hp的感染率及Ca-gA+Hp占Hp感染的比例,并作组间比较.结果消化性溃疡时,Hp及CagA+Hp的感染率以及CagA+Hp与Hp感染者之比率均明显高于正常对照组,统计学差异显著(P＜0.01).结论Hp与十二指肠球部溃疡及胃溃疡的发生高度相关,其感染率达90%以上,其中产CagA型Hp又占九成以上,可见CagA+Hp感染与消化性溃疡关系密切,这在消化溃疡的防治中应引起足够的重视.     

人胃上皮细胞中幽门螺杆菌CagA相关未知磷酸化蛋白和磷酸化位点分析

背景：细胞毒素相关基因A蛋白（CagA）是Ⅰ型幽门螺杆菌（H.pylori）的主要毒力因子。H.pylori胃癌、胃炎相关株和CagA缺失（△CagA）株的蛋白质组学研究尚未发现CagA相关生物标记蛋白。目的：分析H.pyloriCagA阳性株和△CagA株作用后人胃上皮细胞中差异表达的未知磷酸化蛋白和磷酸化位点,为研究CagA的致病机制提供线索。方法：以金属离子亲和吸附富集技术富集经H.pylori标准株和△CagA株作用4h的人胃腺癌细胞株AGS的磷酸化蛋白,双向电泳（2-DE）分离蛋白,飞行时间质谱（TOF-MS）技术鉴定差异蛋白点。结果：H.pylori标准株作用后,AGS细胞FAM50A蛋白276位丝氨酸发生磷酸化,PQBP1蛋白227～251序列中有磷酸化位点。与H.pylori标准株相比,△CagA株作用于AGS细胞可引起至少13种未知磷酸化蛋白的变化,其质谱图中均出现中性丢失峰,其中2种表达量增加,4种表达量降低,6种消失,1种新发生磷酸化。结论：CagA阳性H.pylori感染可致AGS细胞FAM50A和PQBP1蛋白发生磷酸化。所发现的13种未知磷酸化蛋白为揭示CagA的致病机制提供了线索。     

幽门螺杆菌cagA/CagA分子生物学研究进展

幽门螺杆菌(Helicobacter pylori,Hp)感染人数众多,但临床表现各异。大部分感染者终生无症状,但部分感染者会发展为慢性胃炎、十二指肠炎、消化性溃疡、胃癌、粘膜相关胃淋巴瘤。Hp感染之所以有不同结局,在于菌株间存在致病力差异。Hp的致病因子包括菌毛、鞭毛、尿素酶、粘附素、细胞空泡毒素(vacuolization cytotoxin,VacA)、细胞毒素相关基因(cytotoxinassociated gene A,cagA)产物等,一些国家的流行病学研究表明,含细胞毒素相关基因,表达细胞毒素相关抗原A(cytotoxinassociated antigen A,CagA)的Hp菌株感染与十二指肠溃疡和胃癌等严重胃肠疾病发生有关,使cagA/CagA备受各国学者关注。最近,CagA进入宿主细胞后被磷酸化并导致宿主细胞形态改变的报道,为阐明CagA的致病作用和机制提供了契机,使得CagA的功能成为目前Hp研究的热点之一。     

幽-螺杆菌cagA/CagA分子生物学研究进展

幽门螺杆菌(Helicobacterpylori,Hp)感染人数众多,但临床表现各异.大部分感染者终生无症状,但部分感染者会发展为慢性胃炎、十二指肠炎、消化性溃疡、胃癌、粘膜相关胃淋巴瘤Hp感染之所以有不同结局,在于菌株间存在致病力差异.     

高糖对大鼠脂肪细胞胰岛素信号蛋白磷酸化的影响

目的 探讨高浓度葡萄糖（高糖）对原代培养大鼠脂肪细胞的葡萄糖转运活动、胰岛素信号蛋白磷酸化及表达的影响。方法 分离的大鼠脂肪细胞在5，10，15和25mmol/L葡萄糖中孵育24h，然后测定：糖转运活动；胰岛素受体（IR）、胰岛素受体底物（IRS）1、2及蛋白激酶B（PKB）的磷酸化；IRS1，IRS2，肌醇磷脂－3－激酶85亚单位（p85)和PKB的蛋白表达。结果 高糖抑制了这些细胞的葡萄糖转运活动，削弱了IR、IRS1的酪氨酸磷酸化及PKB的丝氨酸磷酸化；下调IRS1而上调IRS2蛋白表达。结论 高糖能抑制脂肪细胞的糖转运活动，诱导胰岛素抵抗。其作用机制与影响胰岛素信号蛋白多部位的磷酸化及蛋白表达有关。     

幽门螺杆菌细胞毒素相关蛋白A与脑梗死的关系

目的探讨幽门螺杆菌(HP)细胞毒素相关蛋白A(cagA)与动脉粥样硬化性脑梗死的关系。方法测定60例动脉粥样硬化性脑梗死患者(脑梗死组)的cagA-HP-IgG抗体、中性粒细胞、超敏C-反应蛋白(hs-CRP)、血纤维蛋白原,应用颈部彩色多普勒超声仪进行颈部血管检测,并与50名健康对照者进行比较。结果脑梗死组cagA-HP抗体阳性率为62%,健康对照组为34%,两组相比差异有显著性(P0.05)。HP抗体阳性者颈动脉斑块和狭窄的发生率分别为92%和62%,健康对照组分别为52%和26%,差异有显著性(P0.05)。HP抗体阳性组较阴性组血hsCRP及纤维蛋白原明显升高(均P0.05)。结论cagA阳性菌株感染与动脉粥样硬化性脑梗死有关,且可能是脑梗死的独立危险因素。     

幽门螺杆菌CagA与宿主细胞相互作用机制的研究进展

细胞毒素相关蛋白A（CagA）是幽门螺杆菌（Helicobacter pylori,H.pylori）感染导致宿主产生炎性反应的重要效应蛋白。H.pylori感染后通过cag PAI编码的Ⅳ型分泌系统将CagA注入宿主细胞内并发生磷酸化,导致细胞内信号传导等一系列的反应。作为H.pylori的一个重要致病因子,CagA蛋白是目前研究的热点之一。本文主要概述了CagA的特征,以CagA易位进入胃黏膜上皮细胞直至引起细胞内信号传导发生改变为主线,综述了近年来与之相关的研究和发现。     

幽门螺杆菌CagA对慢性胃炎患者血清IFN-γ、IL-4、TGF-β和IL-17A表达的影响

目的 探讨幽门螺杆菌（Helicobacter pylori,H.pylori） CagA蛋白对慢性胃炎患者外周血IFN-γ、IL-4、TGF-β和IL-17A表达的影响.方法 检测80例慢性胃炎患者血清中抗CagA抗体,取胃黏膜行病理检查,采用ELISA法检测血清中IFN-γ、IL-4、TGF-β和IL-17A的浓度.结果 CagA抗体阳性组中中性粒细胞的浸润程度显著高于阴性组,两组间H.pylori的菌密度差异无统计学意义,性别对上述因素无显著影响.CagA抗体阳性组血清IFN-γ、IL-17A的表达显著下降,而IL-4、TGF-β的表达显著上升.结论 慢性胃炎CagA 阳性患者的胃黏膜炎症程度更重,机体无法有效清除H.pylori在胃黏膜中的定植,其原因可能与CagA 阳性患者外周血中细胞因子IFN-γ、IL-17A表达水平下降,而IL-4、TGF-β表达水平上升有关.     

细胞毒素相关基因A阳性幽门螺杆菌感染与脑梗死的关系

目的：研究幽门螺杆菌（HP）及其细胞毒素相关蛋白A（CagA）阳性菌株感染与脑梗死的相关性。方法：采用病例对照研究研究,选择发病1周内的脑梗死住院患者（病例组,n=70）以及年龄和性别相匹配的门诊体检人群（对照组,n=30）,检测血清HP IgG抗体和HPCagA阳性菌株IgG抗体的浓度和阳性率,调查两组传统高危因素分布情况、生活习惯、幼时和成人期社会经济状况,探讨HP和CagA阳性菌株血清抗体浓度和阳性率与脑梗死及其病因学亚型的关系。结果：病例组血清HPIgG抗体阳性率和水平与对照组无显著差异,血清CagAIgG抗体阳性率（P〈0．05）和浓度（P〈0．01）均显著高于对照组。多因素回归分析显示,CagA菌株血清学阳性为脑梗死发病的独立危险因素。亚组分析表明,大动脉粥样硬化性脑梗死组血清CagA菌株IgG抗体的阳性率和浓度显著高于对照组（P〈0．05）。结论：产CagA的高毒力HP菌株感染可能是脑梗死的高危因素。     

CDX2 expression is induced by Helicobacter pylori in AGS cells

Data from 753 patients with single adenocarcinomas of the large intestine diagnosed and treated at Trondheim Regional and University Hospital between 1964 and 1978 were studied to determine the influence of tumour site on survival by adjusting for tumour stage, age, and sex. The Cox regression model was used. Although the clinicopathologic stage had the strongest association with prognosis, the tumour site independently influenced the mortality, which increased from the right colon via the transverse/left part of the colon to the rectum.     

Association of CagA+ Helicobacter pylori infection with aortic atheroma

BACKGROUND: To investigate possible association between infection with CagA(+) strains of Helicobacter pylori and aortic atheroma diagnosed by transesophageal echocardiography. METHODS AND RESULTS: One hundred and eighty-eight consecutive subjects prospectively examined for presence of aortic atheroma (localized intimal thickening of >/=3mm) by transesophageal echocardiography were tested for serum IgG antibodies against H. pylori (enzyme-linked immunosorbent assay) and CagA protein (Western blot assay). The association between infection with H. pylori, CagA status of the infecting H. pylori strains, and aortic atherosclerosis was evaluated after adjusting for coronary artery disease risk factors. There was a linear trend for presence of atheroma in subjects with CagA-positive H. pylori infection (51/81, 63%) compared to subjects with CagA-negative H. pylori infection (21/45, 46.7%) and uninfected subjects (18/62, 29%) (p=0.003). H. pylori seropositivity was not associated with aortic atheroma (OR 2.9; 95% CI, 0.8-10.3; p=0.11) when CagA status is not taken into account. On multivariate analysis, parameters associated with risk of aortic atheroma were CagA-positive H. pylori seropositivity (OR 4.4; 95% CI, 1.4-14.7; p=0.01), older age (OR 1.2; 95% CI, 0.9-14.7; p=0.01), having ever smoked cigarettes (OR 3.6; 95% CI, 1.3-10.0; p<0.001), and elevated serum triglyceride level (OR 3.4; 95% CI, 1.3-9.4; p=0.02). CONCLUSIONS: After controlling for H. pylori infection and coronary artery disease risk factors, infection with a CagA-positive strain of H. pylori was independently associated with aortic atherosclerosis. This study suggests a gradient of atherosclerosis between uninfected individuals and patients with CagA-positive H. pylori infection and should prompt research into the role of CagA-positive H. pylori infection in the inflammatory atherosclerotic process.     

转染试剂及幽门螺杆菌对AGS细胞形态的影响

目的:探讨不同的转染试剂对AGS细胞形态的影响,观察这些转染试剂能否像幽门螺杆菌那样引起AGS细胞蜂鸟状改变．方法:用多聚阳离子转染试剂(多聚乙酰亚胺、梭华-Sofast)和改良的脂类转染试剂 (Effectene Transfection Reagent)分别转染AGS 细胞,观察细胞形态的变化．用幽门螺杆菌 26695菌株攻击AGS细胞,观察细胞形态的变化并与经转染试剂作用的细胞进行形态比较．结果:幽门螺杆菌攻击后4 h能引起AGS细胞发生蜂鸟状改变．两种多聚阳离子转染试剂也均能引起AGS细胞发生蜂鸟状改变,与幽门螺杆菌引起的细胞形态改变相似,大部分细胞拉长,并且不受是否转染DNA的影响．此种变化在转染4 h时便出现,与试剂剂量的增加呈正相关．当PEI的剂量为10 μL时,细胞出现凋亡,15μL时凋亡加重．改良的脂类转染试剂对 AGS细胞的形态未产生影响．结论:在研究引起AGS细胞形态改变的因素时,不宜选择多聚阳离子转染试剂;多聚阳离子引起的AGS细胞形态改变与幽门螺杆菌引起的AGS细胞形态改变之间是否存在关系值得进一步研究．     

Influence of EPIYA-repeat polymorphism on the phosphorylation-dependent biological activity of Helicobacter pylori CagA

BACKGROUND & AIMS: Helicobacter pylori CagA-positive strain is associated with gastric adenocarcinoma. CagA is delivered into gastric epithelial cells, where it undergoes tyrosine phosphorylation at the EPIYA sites by Src family kinases (SFKs). Owing to homologous recombination within the 3'-region of the cagA gene, 4 distinct EPIYA sites, each of which is defined by surrounding sequences, are variably assembled in both number and order among CagA proteins from different clinical H pylori isolates. Tyrosine-phosphorylated CagA specifically binds and deregulates SHP-2 via the Western CagA-specific EPIYA-C or East Asian CagA-specific EPIYA-D site, and C-terminal Src kinase (Csk) via the EPIYA-A or EPIYA-B site. Here we investigated the influence of EPIYA-repeat polymorphism on the CagA activity. METHODS: A series of EPIYA-repeat variants of CagA were expressed in AGS gastric epithelial cells and the ability of individual CagA to bind SHP-2 or Csk was determined by the sequential immunoprecipitation and immunoblotting method. RESULTS: CagA proteins carrying multiple EPIYA-C or EPIYA-D sites bound and deregulated SHP-2 more strongly than those having a single EPIYA-C or EPIYA-D. Furthermore, the ability of CagA to bind Csk was correlated with the number of EPIYA-A and EPIYA-B sites. Because Csk inhibits SFK, CagA with greater Csk-binding activity more strongly inhibited Src-dependent CagA phosphorylation and more effectively attenuated induction of cell elongation caused by CagA-SHP-2 interaction. CONCLUSIONS: EPIYA-repeat polymorphism of CagA greatly influences the magnitude and duration of phosphorylation-dependent CagA activity, which may determine the potential of individual CagA as a bacterial virulence factor that directs gastric carcinogenesis.     

Time-series gene expression prof iles in AGS cells stimulated with Helicobacter pylori

AIM: To extend the knowledge of the dynamic interaction between Helicobacter pylori (H. pylori) and host mucosa. METHODS: A time-series cDNA microarray was performed in order to detect the temporal gene expression prof iles of human gastric epithelial adenocarcinoma cells infected with H. pylori. Six time points were selected to observe the changes in the model. A differential expression prof ile at each time point was obtained by comparing the microarray signal value with that of 0 h. Real-time polymerase ...     

Altered states: involvement of phosphorylated CagA in the induction of host cellular growth changes by Helicobacter pylori

Helicobacter pylori, present in half of the world's population, is a very successful pathogen. It can survive for decades in the human stomach with few obvious consequences to the host. However, it is also the cause of gastric diseases ranging from gastritis to ulcers to gastric cancer and has been classified a type 1 carcinogen by the World Health Organization. We have previously shown that phosphorylation of a 145-kDa protein and activation of signal transduction pathways are associated with the attachment of H. pylori to gastric cells. Here we identify the 145-kDa protein as the H. pylori CagA protein. We also show that CagA is necessary to induce a growth-factor-like phenotype (hummingbird) in host gastric cells similar to that induced by hepatocyte growth factor (HGF). Additionally, we identify a second cellular phenotype induced after attachment by H. pylori, which we call SFA (stress fiber associated). SFA is CagA independent and is produced by type I and type II H. pylori.