Translocation of Helicobacter pylori CagA into gastric epithelial cells by type IV secretion

The Gram-negative bacterium Helicobacter pylori is a causative agent of gastritis and peptic ulcer disease in humans. Strains producing the CagA antigen (cagA(+)) induce strong gastric inflammation and are strongly associated with gastric adenocarcinoma and MALT lymphoma. We show here that such strains translocate the bacterial protein CagA into gastric epithelial cells by a type IV secretion system, encoded by the cag pathogenicity island. CagA is tyrosine-phosphorylated and induces changes in the tyrosine phosphorylation state of distinct cellular proteins. Modulation of host cells by bacterial protein translocation adds a new dimension to the chronic Helicobacter infection with yet unknown consequences.     

Natural antibiotic function of a human gastric mucin against Helicobacter pylori infection

Helicobacter pylori infects the stomachs of nearly a half the human population, yet most infected individuals remain asymptomatic, which suggests that there is a host defense against this bacterium. Because H. pylori is rarely found in deeper portions of the gastric mucosa, where O-glycans are expressed that have terminal alpha1,4-linked N-acetylglucosamine, we tested whether these O-glycans might affect H. pylori growth. Here, we report that these O-glycans have antimicrobial activity against H. pylori, inhibiting its biosynthesis of cholesteryl-alpha-D-glucopyranoside, a major cell wall component. Thus, the unique O-glycans in gastric mucin appeared to function as a natural antibiotic, protecting the host from H. pylori infection.     

Regulation of the polarity protein Par6 by TGFbeta receptors controls epithelial cell plasticity

The transition of cells from an epithelial to a mesenchymal phenotype is a critical event during morphogenesis in multicellular organisms and underlies the pathology of many diseases, including the invasive phenotype associated with metastatic carcinomas. Transforming growth factor beta (TGFbeta) is a key regulator of epithelial-to-mesenchymal transition (EMT). However, the molecular mechanisms that control the dissolution of tight junctions, an early event in EMT, remain elusive. We demonstrate that Par6, a regulator of epithelial cell polarity and tight-junction assembly, interacts with TGFbeta receptors and is a substrate of the type II receptor, TbetaRII. Phosphorylation of Par6 is required for TGFbeta-dependent EMT in mammary gland epithelial cells and controls the interaction of Par6 with the E3 ubiquitin ligase Smurf1. Smurf1, in turn, targets the guanosine triphosphatase RhoA for degradation, thereby leading to a loss of tight junctions. These studies define how an extracellular cue signals to the polarity machinery to control epithelial cell morphology.     

Helicobacter pylori SabA adhesin in persistent infection and chronic inflammation

Helicobacter pylori adherence in the human gastric mucosa involves specific bacterial adhesins and cognate host receptors. Here, we identify sialyl-dimeric-Lewis x glycosphingolipid as a receptor for H. pylori and show that H. pylori infection induced formation of sialyl-Lewis x antigens in gastric epithelium in humans and in a Rhesus monkey. The corresponding sialic acid-binding adhesin (SabA) was isolated with the "retagging" method, and the underlying sabA gene (JHP662/HP0725) was identified. The ability of many H. pylori strains to adhere to sialylated glycoconjugates expressed during chronic inflammation might thus contribute to virulence and the extraordinary chronicity of H. pylori infection.     

Molecular hydrogen as an energy source for Helicobacter pylori

The gastric pathogen Helicobacter pylori is known to be able to use molecular hydrogen as a respiratory substrate when grown in the laboratory. We found that hydrogen is available in the gastric mucosa of mice and that its use greatly increased the stomach colonization by H. pylori. Hydrogenase activity in H. pylori is constitutive but increased fivefold upon incubation with hydrogen. Hydrogen concentrations measured in the stomachs of live mice were found to be 10 to 50 times as high as the H. pylori affinity for hydrogen. A hydrogenase mutant strain is much less efficient in its colonization of mice. Therefore, hydrogen present in animals as a consequence of normal colonic flora is an energy-yielding substrate that can facilitate the maintenance of a pathogenic bacterium.     

组织块种植法体外培养奶牛乳腺上皮细胞

为建立成熟的奶牛乳腺上皮细胞体外培养体系,以组织块种植法培养荷斯坦泌乳期成年母牛乳腺组织,观测长出的上皮细胞在各生长时期的形态变化,绘制生长曲线并计算群体倍增时间,用免疫组化技术鉴定乳腺上皮细胞角蛋白18的表达,用SDS-PAGE电泳和免疫印迹分析技术检测乳腺细胞的酪蛋白分泌情况。试验结果表明,此培养体系可获得良好的奶牛乳腺上皮细胞,原代以及传代培养,细胞增殖旺盛,长势良好;细胞骨架蛋白——角蛋白18表达为阳性,且培养的细胞具有分泌牛乳酪蛋白的功能。     

幽门螺杆菌毒蛋白——空泡毒素研究进展

幽门螺杆菌（Hp）是人体内常见的病原微生物,现发现其与胃癌的发生密切相关。VacA作为Hp感染的一种主要并且重要的毒力因子,推测其在胃癌发生过程中可能起着较为重要的作用。对VacA基因、蛋白的分子结构和研究现状以及VacA诱发细胞毒性的机制做一综述。     

Extrusion and death of DPP/BMP-compromised epithelial cells in the developing Drosophila wing

During animal development, epithelial cell fates are specified according to spatial position by extracellular signaling pathways. Among these, the transforming growth factor beta/bone morphogenetic protein (TGF-beta/BMP) pathways are evolutionarily conserved and play crucial roles in the development and homeostasis of a wide range of multicellular tissues. Here we show that in the developing Drosophila wing imaginal epithelium, cell clones deprived of the BMP-like ligand Decapentaplegic (DPP) do not die as previously thought but rather extrude from the cell layer as viable cysts exhibiting marked abnormalities in cell shape and cytoskeletal organization. We propose that in addition to assigning cell fates, a crucial developmental function of DPP/BMP signaling is the position-specific control of epithelial architecture.     

Host resistance to lung infection mediated by major vault protein in epithelial cells

The airway epithelium plays an essential role in innate immunity to lung pathogens. Ribonucleoprotein particles primarily composed of major vault protein (MVP) are highly expressed in cells that encounter xenobiotics. However, a clear biologic function for MVP is not established. We report here that MVP is rapidly recruited to lipid rafts when human lung epithelial cells are infected with Pseudomonas aeruginosa, and maximal recruitment is dependent on bacterial binding to the cystic fibrosis transmembrane conductance regulator. MVP was also essential for optimal epithelial cell internalization and clearance of P. aeruginosa. These results suggest that MVP makes a substantial contribution to epithelial cell-mediated resistance to infection.     

Regulation of leptin in involution of mammary gland

Leptin,a protein hormone produced and secreted predominantly by white adipose tissue,has a critical role in the regulation and coordination of energy metabolism.Leptin is produced in the mammary gland by the fat tissue or by the mammary epithelium.In vitro study has shown that leptin triggers apoptosis in mammary epithelial cells.Mammary gland involution is characterized by extensive apoptosis of the epithelial cells.At the onset of involution,STAT3 is specifically activated.Various studies show that leptin act as a paracrine and autocrin factor to influence mammary epithelial cell proliferation and differentiation.This paper reviewed the function of leptin to the involution of mammary gland.     

Effect of Semen vaccariae and Taraxacumogono on CellAdhesion of Bovine Mammary Epithelial Cells

The aim of this study is to reveal the regulation mechanism of the effect of Semen vaccariae and Taraxacu mogono on the cell-cell adhersion molecule, E-cadherin and b-catenin on the proliferation role and secretion function of bovine mammary epithelial cells cultured in vitro. Firstly, the epithelial character of bovine mammary epithelial cells was authenticated using immunofluorescence, then the cell grow curve was observed and investigated after S. vaccariae and T. mogono treatment. On the effect of S. vaccariae and T. mogono, cell adhesion molecules E-cadherin, b-catenin and CycinD1 mRNA and protein were detected by qRT-PCR and Western blotting, respectively. The results showed that the cellular keratin 18 expressed positively and proliferated vigorously after S. vaccariae and T. mogono treament. The mRNA and protein levels of E-cadherin and CycinD1 were remarkably higher (P<0.05) in 36 h after S. vaccariae and T. mogono treatment. The cell proliferation at 36 h was increased significantly (P<0.05). In conclusion, S. vaccariae and T. mogono have a positive impact on the cell proliferation and an effect on the adhesion molecules E-cadherin, b-catenin and CycinD1 in the Wnt signaling pathway.     

绍鸭腺胃蛙皮素细胞生长发育的免疫组织化学观测

采用免疫组织化学ABC方法，显示绍兴麻鸭胚后期腺胃蛙皮素免疫反应细胞（P细胞）的形态及其分布，分别计数每个周龄阶段的腺胃腺叶和表面上皮中蛙皮素免疫反应细胞的数量，并进行了统计学分析。结果表明：P细胞形态多样，以卵圆形、多面体形为主，并且有胞质突起。P细胞多分散分布于腺叶的中间与内侧区，个别分布在表面上皮中。腺叶P细胞的生长峰期为0～6周龄，以后下降，表面上皮P细胞生长峰期为0～10周龄，以后迅速下降。各周龄腺叶P细胞数明显多于表面上皮P细胞数。     

六月雪水提取物对乙醇损伤的人胃黏膜上皮细胞的保护作用

前期研究发现六月雪[Serissa serissoides(DC.)Druce]对乙醇诱导的大鼠胃黏膜损伤有良好的保护作用,因此进一步在细胞水平上探讨六月雪水提取物对乙醇损伤的人胃黏膜上皮细胞的保护作用。采用体外细胞培养人胃黏膜上皮细胞系GES-1细胞,将GES-1细胞用0~10%的乙醇孵育4~6 h,建立胃黏膜损伤模型。将参试GES-1细胞分为正常组、模型组、荆花胃康胶丸组、六月雪水提取物剂量组,正常组不做任何处理培养24 h,其他组加入一定浓度的乙醇处理一段时间后,加入含荆花胃康胶丸、六月雪水提取物各浓度剂量的培养基,正常组、模型组不加入药物,继续培养24 h,利用MTT检测各组GES-1细胞的活性。将MTT筛选后效果最佳的六月雪3个浓度以及荆花胃康胶丸组1个浓度分别定为高、中、低剂量组和阳性药物组,运用吖啶橙荧光染色法检测各组细胞凋亡情况,采用Western-Blot法检测各试验组碱性成纤维细胞生长因子(b FGF)蛋白的表达情况。结果表明,5%的乙醇孵育GES-1细胞4 h是造成胃黏膜损伤的最佳细胞模型,对GES-1细胞的抑制率达到40%。六月雪水提取物组中,60、70、80μg/m L 3个浓度效果最佳,与该组其他浓度比较差异显著(P0.05);荆花胃康胶丸组中,在浓度为160μg/m L时细胞增殖最明显;均高于其他浓度的荆花胃康胶丸组;吖啶橙染色后显微镜下观察正常GES-1细胞形态均一、生长良好,而模型组大量细胞明显出现衰老或凋亡,荆花胃康胶丸组、六月雪水提取物组GES-1细胞生长情况明显好于模型组;模型组b FGF的蛋白表达水平明显高于正常组,差异显著(P0.05);与模型组比较,六月雪水提取物组的b FGF蛋白表达水平明显增加,差异极显著(P0.01);六月雪水提取物组与荆花胃康胶丸组比较,b FGF的表达水平差异也达极显著水平(P0.01)。说明六月雪水提取物可以保护乙醇损伤的人胃黏膜上皮系GES-1细胞,可以增加b FGF的蛋白表达水平,提高溃疡愈合速度。     

人胃腺癌上皮钙粘素的表达及其意义

目的 :探讨上皮钙粘素 ( E- cd)在人胃腺癌中的表达及其意义。方法 :应用免疫组化 S- P法检测 1 0例正常胃粘膜、1 0例异型增生、92例胃腺癌 E- cd的表达。结果 :E- cd在异型增生、早期和进展期胃癌阳性表达率分别为 80 % ( 8/1 0 )、61 .5 % ( 8/1 3)和 48.1 % ( 38/79) ,三者之间差异有显著性 ( P<0 .0 1 )。 E- cd阳性表达与胃癌生长方式、组织学类型、TNM分期及患者的预后显著相关。 E- cd的阳性表达率下降主要见于弥漫型胃癌。结论 :E- cd阳性表达同胃癌分化及生物学行为密切相关 ,是预测其侵袭转移和判断预后有价值的参考指标。     

热应激对奶山羊瘤胃上皮细胞屏障通透性的影响

【目的】研究热应激对奶山羊瘤胃上皮细胞屏障通透性的影响,为动物在炎热环境中能够维持正常生理机能以及探索促进动物抗热应激的方法提供理论基础和试验依据。【方法】选用泌乳中后期奶山羊,采用逐渐加热的方式建立奶山羊热应激模型,研究热应激对奶山羊血浆中D-乳酸、DAO、内毒素及炎性细胞因子等异常代谢产物的浓度,瘤胃上皮细胞间紧密连接的变化及紧密连接蛋白Occludin表达的影响。【结果】①热应激显著提高了血浆中D-乳酸和DAO浓度;②热应激显著提高了血浆中内毒素及炎性细胞因子TNF-α、IL-1α、IL-6、IL-1β、干扰素-γ的浓度;③热应激破坏了瘤胃上皮间紧密连接的结构,并显著降低了紧密连接蛋白Occludin蛋白表达和mRNA表达。【结论】热应激可导致奶山羊瘤胃黏膜屏障功能受损、通透性增加、菌群移位,其机制可能与瘤胃上皮细胞紧密连接蛋白Occludin表达下降有关。     

灰雁胃肠道显微及超微结构观察

为丰富鸟类形态学资料,同时为灰雁消化生理的研究奠定基础。应用HE染色技术及透射电镜技术对成年灰雁胃肠道组织学结构进行观察。结果表明,灰雁的胃腺上皮细胞内细胞器丰富,酶原颗粒数量较多;十二指肠绒毛较高,固有层肠腺密集且直径较大,电镜下观察,上皮细胞表面的微绒毛排列紧密,长度大于肠道各段,柱状细胞胞质中线粒体极为发达,腺上皮有大量内分泌细胞分布;空肠微绒毛较短,排列疏松,杯状细胞数量较多;回肠柱状细胞胞质中的细胞器不发达,上皮细胞表面的微绒毛更短,固有层的弥散淋巴组织发生聚集;盲肠和直肠的上皮细胞表面无微绒毛,杯状细胞和淋巴组织较多;直肠的肌层明显厚于肠道各段,肠腺直径较大,多呈圆形。实验结果表明,灰雁的胃腺细胞可能同时具有主细胞和壁细胞的功能。     

FLCN对奶牛乳腺上皮细胞增殖及泌乳功能的影响

FLCN基因参与多种代谢途径和细胞过程,国内外关于FLCN在奶牛乳腺发育过程中表达及调节的研究鲜有报道。应用RNA干扰技术和质粒转染技术改变FLCN基因在奶牛乳腺上皮细胞中表达量,流式细胞仪检测细胞增殖,采用qRT-PCR和Western blot检测FLCN对泌乳相关功能基因AMPK、mTOR、CyclinD1、Caspase3和β-酪蛋白表达的影响。结果表明,FLCN正向调节mTOR磷酸化水平,促进乳蛋白合成和细胞增殖,抑制细胞凋亡,负调控能量代谢调节子AMPK。FLCN在奶牛乳腺上皮细胞中可通过mTOR信号通路调控细胞增殖及乳蛋白合成,研究对揭示FLCN调控奶牛乳腺上皮细胞增殖和泌乳具有重要作用。     

幽门螺杆菌空泡毒素及其单克隆抗体的研究进展

人幽门螺杆菌（H.pylori）是慢性胃炎和消化性溃疡的主要病因，并与胃癌的发生密切相关。幽门螺杆菌的致病机理与其致病性和宿主免疫应答有关，尤以幽门螺杆菌的毒性占主导地位。最新研究表明，约60%的幽门螺杆菌分离株具有分泌空泡毒素（VacA）的能力，并且血清中其相应抗体的出现与消化性溃疡的发生高度平行。综述了VacA的制备和纯化，理化特性，蛋白质结构，编码基因，致病机理及其单克隆抗体等方面的研究进展。