Gastric Surface Epithelial Cells Research Articles

Research Progress of Helicobacter pylori-Associated Extragastric Diseases

Helicobacter pylori (Hp) is a common Gram-negative bacillus causing gastrointestinal infections.It mainly exists on the surface of gastric epithelial cells and in mucus and is associated with gastric ulcers,gastric cancer,and gastric mucosa-associated lymphomas.Studies have shown that Hp can induce or exacerbate certain extragastric diseases and is associated with the occurrence of coronavirus disease 2019.It is hypothesized that Hp may be indirectly or directly involved in the occurrence and development of diseases by stimulating the production of inflammatory cytokines or inducing cross-immune reactions.In addition,Hp can enter Candida to release toxins continuously and play a role in escaping the recognition of the host immune system and the bactericidal effect of drugs.This article reviews the research progress in Hp-associated extragastric diseases in recent years,aiming to draw the attention of clinical workers to Hp-associated extragastric diseases and enrich the knowledge about Hp infection for formulating countermeasures to avoid the aggravation or triggering of other diseases by Hp.

Convergent gene losses and pseudogenizations in multiple lineages of stomachless fishes

The regressive evolution of independent lineages often results in convergent phenotypes. Several teleost groups display secondary loss of the stomach, and four gastric genes, atp4a, atp4b, pgc, and pga2 have been co-deleted in agastric (stomachless) fish. Analyses of genotypic convergence among agastric fishes showed that four genes, slc26a9, kcne2, cldn18a, and vsig1, were co-deleted or pseudogenized in most agastric fishes of the four major groups. kcne2 and vsig1 were also deleted or pseudogenized in the agastric monotreme echidna and platypus, respectively. In the stomachs of sticklebacks, these genes are expressed in gastric gland cells or surface epithelial cells. An ohnolog of cldn18 was retained in some agastric teleosts but exhibited an increased non-synonymous substitution when compared with gastric species. These results revealed novel convergent gene losses at multiple loci among the four major groups of agastric fish, as well as a single gene loss in the echidna and platypus.

Unwelcome guests - the role of gland-associated Helicobacter pylori infection in gastric carcinogenesis.

Helicobacter pylori (H. pylori) are Gram-negative bacteria that cause chronic gastritis and are considered the main risk factor for the development of gastric cancer. H. pylori have evolved to survive the harsh luminal environment of the stomach and are known to cause damage and signaling aberrations in gastric epithelial cells, which can result in premalignant and malignant pathology. As well as colonizing the gastric mucus and surface epithelial cells, a subpopulation of H. pylori can invade deep into the gastric glands and directly interact with progenitor and stem cells. Gland colonization therefore bears the potential to cause direct injury to long-lived cells. Moreover, this bacterial subpopulation triggers a series of host responses that cause an enhanced proliferation of stem cells. Here, we review recent insights into how gastric gland colonization by H. pylori is established, the resulting pro-carcinogenic epithelial signaling alterations, as well as new insights into stem cell responses to infection. Together these point towards a critical role of gland-associated H. pylori in the development of gastric cancer.

Identification of Desmoglein-2 as a novel target of Helicobacter pylori HtrA in epithelial cells

BackgroundHigh temperature requirement A (HtrA) is an active serine protease secreted by the group-I carcinogen Helicobacter pylori (H. pylori). The human cell adhesion protein and tumor suppressor E-cadherin (hCdh1) expressed on the surface of gastric epithelial cells was identified as the first HtrA substrate. HtrA-mediated hCdh1 cleavage and subsequent disruption of intercellular adhesions are considered as important steps in H. pylori pathogenesis. In this study, we performed a proteomic profiling of H. pylori HtrA (HpHtrA) to decipher the complex mechanism of H. pylori interference with the epithelial barrier integrity.ResultsUsing a proteomic approach we identified human desmoglein-2 (hDsg2), neuropilin-1, ephrin-B2, and semaphorin-4D as novel extracellular HpHtrA substrates and confirmed the well characterized target hCdh1. HpHtrA-mediated hDsg2 cleavage was further analyzed by in vitro cleavage assays using recombinant proteins. In infection experiments, we demonstrated hDsg2 shedding from H. pylori-colonized MKN28 and NCI-N87 cells independently of pathogen-induced matrix-metalloproteases or ADAM10 and ADAM17.ConclusionsCharacterizing the substrate specificity of HpHtrA revealed efficient hDsg2 cleavage underlining the importance of HpHtrA in opening intercellular junctions.6h_G33ukTTgCSbc2oAPkedVideo

Mechanical properties of the surface of gastric epithelial cells in patients with oncologic pathology

Objective:to study the efficiency of the application of atomic force microscopy for the identification of differences in the structural and mechanical properties of gastric epithelial cells in normal conditions and in gastric cancer.Material and methods.The structural and mechanical properties of the membrane of the epithelial cells of the gastric mucosa in 7 patients with gastric cancer were assessed using atomic force microscopy in contact mode.Results.The comparison of the size and shape of gastric mucous cells (GLC), their healthy and tumor areas has showed that in both the cases they have a slightly elongated rounded shape and similar dimensions: length × width × height of the cell is norm (in μm): 7.5 × 6.8 × 0.6, and in case of oncologic pathology (in μm): 7.2 × 6.9 × 1.0. Tumor cells are characterized by a 13% increase in their surface roughness compared to normal epithelial cells. The lateral force microscopy method allows of obtaining data on the structure of the submembrane cortical layer of the cell cytoskeleton. According to experimental data, a 2.48-fold decrease in the value of the friction force (Fl) in epithelial cells from healthy areas of the coolant indicates increased density and integrity of the cortical layer of the cytoskeleton in normal conditions compared to those of tumor cells.Conclusion.The analysis of the experimental data has found that tumor cells from the gastric mucosa differ from healthy cells in terms of their nanomechanical properties: they are characterized by a rougher surface, which consists of fewer structural elements of a larger size. The work has showed the interrelation of the indicators of the frictional properties of the cell surface: the values of the friction forces and the roughness of the friction map.

Histomorphological Characteristics and Pathological Types of Hyperproliferation of Gastric Surface Epithelial Cells.

Objective To investigate the histomorphological characteristics and pathological types of hyperproliferation of gastric surface epithelial cells. Methods Hematoxylin and Eosin, Periodic acid–Schiff, and immunohistochemical staining were performed on biopsy specimens obtained from 723 patients with hyperproliferation of gastric surface epithelial cells and/or hyperplasia of gastric pits. Follow-up gastroscopic reexaminations were performed on 475 patients included. Improvement probability was analyzed using Kaplan-Meyer as well as Cox proportional hazards models. Results Seven different histomorphologies and clinicopathologies of hyperproliferation of gastric surface epithelial cells were identified: (1) common hyperplasia of gastric epithelial cells, which was characterized by focal glandular epithelial hyperplasia of gastric pits with chronic inflammation; (2) drug-induced hyperplasia of gastric epithelial cells, which was characterized by increased hyperplasia of gastric pits and cells arranged in a monolayer; (3) Helicobacter pylori (Hp) infection-induced hyperplasia of gastric epithelial cells, which was characterized by the disappearance of oval, spherical, and bounded membrane-enclosed mucus-containing granules in the cytoplasm and on the nucleus together with cytoplasmic swelling and vacuolation; (4) metaplastic hyperplasia of gastric epithelial cells, which was characterized by the coexistence of intestinal metaplastic cells with hyperplastic gastric epithelial cells; (5) atrophic hyperplasia of gastric epithelial cells, which was characterized by the mucosal atrophy accompanied with hyperplasia of gastric pits; (6) low-grade neoplasia of epithelial cells, which was characterized by the mild to moderate dysplasia of gastric epithelial cells; and (7) high-grade neoplasia of epithelial cells, which was characterized by the evident dysplasia of hyperplastic epithelial cells and losses of cell polarity. The different pathological types are associated with different improvement probabilities. Conclusions This study demonstrated the histomorphological characteristics and pathological types, which might guide clinicians to track malignant cell transformation, perform precise treatment, predict the clinical prognosis, and control the development of gastric cancer.

A novel FRET peptide assay reveals efficient Helicobacter pylori HtrA inhibition through zinc and copper binding

Helicobacter pylori (H. pylori) secretes the chaperone and serine protease high temperature requirement A (HtrA) that cleaves gastric epithelial cell surface proteins to disrupt the epithelial integrity and barrier function. First inhibitory lead structures have demonstrated the essential role of HtrA in H. pylori physiology and pathogenesis. Comprehensive drug discovery techniques allowing high-throughput screening are now required to develop effective compounds. Here, we designed a novel fluorescence resonance energy transfer (FRET) peptide derived from a gel-based label-free proteomic approach (direct in-gel profiling of protease specificity) as a valuable substrate for H. pylori HtrA. Since serine proteases are often sensitive to metal ions, we investigated the influence of different divalent ions on the activity of HtrA. We identified Zn++ and Cu++ ions as inhibitors of H. pylori HtrA activity, as monitored by in vitro cleavage experiments using casein or E-cadherin as substrates and in the FRET peptide assay. Putative binding sites for Zn++ and Cu++ were then analyzed in thermal shift and microscale thermophoresis assays. The findings of this study will contribute to the development of novel metal ion-dependent protease inhibitors, which might help to fight bacterial infections.

Helicobacter pylori Infection of the Gastric Epithelium Promotes Programmed Death Ligand 1 Expression and the Formation of Premalignant Lesions

BackgroundHelicobacter pylori (H. pylori) is the number one risk factor for gastric cancer. Currently the 5‐year‐survival rate for gastric cancer is only 29%. Our laboratory has reported that H. pylori infection results in the up‐regulation of the Sonic Hedgehog (SHH) signaling pathway mediated by an increase in the transcriptional activity of NF‐kB. In addition, H. pylori infection induces the expression of programmed death ligand 1 (PD‐L1) on gastric epithelial cells. This expression inhibits T cell proliferation and effector function.HypothesisH. pylori‐induced PD‐L1 expression on the surface of gastric epithelial cells is mediated by the SHH signaling pathway.MethodsHuman‐derived gastric organoids (huFGOs) were generated from sleeve gastrectomies. These huFGOs were then transferred to a collagen‐coated transwell where they readily formed a 2D gastric epithelial cell monolayer (huGEM). The huGEM culture was apically treated with H. pylori. A second experimental group was also infected with H. pylori, but was treated with Vismodegib, a smoothened inhibitor. Gli2 and PD‐L1 expression was analyzed by qRT‐PCR and immunofluorescence. A chromatin immunoprecipitation (ChIP) assay was used to analyze Gli2 binding to the PD‐L1 promoter region. Gli3 was used as a positive control.Results1) HuGEM cultures infected with H. pylori express significantly more PD‐L1: H. pylori infection significantly increased PD‐L1 expression in huGEM cultures 48 hours post‐infection, when compared to uninfected monolayers. This response was blocked by pretreatment with Hedgehog inhibitor vismodegib. 2) Transcriptionally active Gli2 promotes PD‐L1 expression in H. pylori infected huGEM cultures: Transcriptionally active Gli2 was bound to the zinc finger motif of the promoter region of PD‐L1 upon the infection of gastric epithelial monolayers in response to H. pylori infection.ConclusionH. pylori‐induced PD‐L1 expression is mediated by the SHH signaling pathway within the gastric epithelium. Cells infected with H. pylori that express PD‐L1 may freely gain mutations while being protected from the immune response, creating premalignant lesions progressing to gastric cancer.Support or Funding InformationSteven Goldman Memorial Pancreatic Cancer Research Grant (Zavros) 1RO1DK083402This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Genetic ablation of carbonic anhydrase IX disrupts gastric barrier function via claudin-18 downregulation and acid backflux.

AimThis study aimed to explore the molecular mechanisms for the parietal cell loss and fundic hyperplasia observed in gastric mucosa of mice lacking the carbonic anhydrase 9 (CAIX).MethodsWe assessed the ability of CAIX‐knockout and WT gastric surface epithelial cells to withstand a luminal acid load by measuring the pH i of exteriorized gastric mucosa in vivo using two‐photon confocal laser scanning microscopy. Cytokines and claudin‐18A2 expression was analysed by RT‐PCR.Results CAIX‐knockout gastric surface epithelial cells showed significantly faster pH i decline after luminal acid load compared to WT. Increased gastric mucosal IL‐1β and iNOS, but decreased claudin‐18A2 expression (which confer acid resistance) was observed shortly after weaning, prior to the loss of parietal and chief cells. At birth, neither inflammatory cytokines nor claudin‐18 expression were altered between CAIX and WT gastric mucosa. The gradual loss of acid secretory capacity was paralleled by an increase in serum gastrin, IL‐11 and foveolar hyperplasia. Mild chronic proton pump inhibition from the time of weaning did not prevent the claudin‐18 decrease nor the increase in inflammatory markers at 1 month of age, except for IL‐1β. However, the treatment reduced the parietal cell loss in CAIX‐KO mice in the subsequent months.ConclusionsWe propose that CAIX converts protons that either backflux or are extruded from the cells rapidly to CO 2 and H2O, contributing to tight junction protection and gastric epithelial pH i regulation. Lack of CAIX results in persistent acid backflux via claudin‐18 downregulation, causing loss of parietal cells, hypergastrinaemia and foveolar hyperplasia.

Detection of Helicobacter pylori DNA in Formalin-Fixed Paraffin-Embedded Gastric Biopsies Using Laser Microdissection and qPCR.

Molecular detection and analysis of virulence factors of Helicobacter pylori depends on the specificity of cell selection in the gastric biopsies. The laser microdissection (LM) instruments combine microscopy with laser cut sectioning. This combination allows one to choose only the bacteria that are in direct contact with epithelial cells in the gastric biopsy sample, avoiding those microorganisms attached to the mucus layer in the sample. The average concentration of DNA isolated from 25 cuts with selected bacteria is around 1.94 ng/μL, which is enough DNA to perform a qPCR protocol using real-time instruments to amplify 16sDNA or virulence factors like cagA or vacA. Consequently, the application of these technologies in the molecular analysis of Helicobacter pylori directly in contact with the surface of gastric epithelial cells is more precise and could yield better insights about the complex mechanisms of interactions between pathogen and host. Insights derived from research using the techniques described herein may in future facilitate prevention of infection or improved therapeutic options.

Galectin-3 Plays an Important Role in Innate Immunity to Gastric Infection by Helicobacter pylori.

We studied the role of galectin-3 (Gal3) in gastric infection by Helicobacter pylori We first demonstrated that Gal3 was selectively expressed by gastric surface epithelial cells and abundantly secreted into the surface mucus layer. We next inoculated H. pylori Sydney strain 1 into wild-type (WT) and Gal3-deficient mice using a stomach tube. At 2 weeks postinoculation, the bacterial cells were mostly trapped within the surface mucus layer in WT mice. In sharp contrast, they infiltrated deep into the gastric glands in Gal3-deficient mice. Bacterial loads in the gastric tissues were also much higher in Gal3-deficient mice than in WT mice. At 6 months postinoculation,H. pylori had successfully colonized within the gastric glands of both WT and Gal3-deficient mice, although the bacterial loads were still higher in the latter. Furthermore, large lymphoid clusters mostly consisting of B cells were frequently observed in the gastric submucosa of Gal3-deficient mice.In vitro, peritoneal macrophages from Gal3-deficient mice were inefficient in killing engulfed H. pylori Furthermore, recombinant Gal3 not only induced rapid aggregation of H. pylori but also exerted a potent bactericidal effect on H. pylori as revealed by propidium iodide uptake and a morphological shift from spiral to coccoid form. However, a minor fraction of bacterial cells, probably transient phase variants of Gal3-binding sugar moieties, escaped killing by Gal3. Collectively, our data demonstrate that Gal3 plays an important role in innate immunity to infection and colonization of H. pylori.

The Sialic Acid Binding Adhesin ( SabA ) of Helicobacter Pylori Isolated from Egypt Is Associated with Gastric Cancer

Background: Helicobacter pylori (H. pylori) expressed outer membrane proteins (OMPs) that assist in bacterial adherence to the gastric epithelium promoting successful colonization. One of these OMPs is the blood group antigen binding adhesin A (BabA) which bind to the fucosylated Lewis b blood group antigen (Le b ) on the surface of gastric epithelial cells. Another OMPs is the sialic acid binding adhesin (SabA) that mediates H. pylori binding the specific sialyl dimeric Lewis x glycosphingolipid (Le x ) on the gastric epithelium. A lot of discrepancies about the correlation between the presence of both babA and sabA genes and the apparent clinical outcome of H. pylori infection were reported. Objectives: The present study was to disclose the relationship between the presence of these genes and the clinical outcomes in Egyptian H. pylori patients. Methodology: Forty three H. pylori strains were isolated from patients with different clinical findings. Polymerase chain reaction (PCR) for detecting the presence of babA and sabA genes was performed using different sets of primers for detecting different regions of the gene. Further bioinformatics analysis for the sabA product was done using KEGG and Pfam websites. Results: evincing striking correlation between sabA presence and the gastric cancer disease. However, we could not find any correlation between presence of babA and the associated diseases. Conclusions: SabA is one of the H. pylori OMPs adhesins involving in increasing the risk of H. pylori associated gastric cancer in H. pylori Egyptian patients.

The gastroprotective effects of Eugenia dysenterica (Myrtaceae) leaf extract: the possible role of condensed tannins.

We applied a taxonomic approach to select the Eugenia dysenterica (Myrtaceae) leaf extract, known in Brazil as "cagaita," and evaluated its gastroprotective effect. The ability of the extract or carbenoxolone to protect the gastric mucosa from ethanol/HCl-induced lesions was evaluated in mice. The contributions of nitric oxide (NO), endogenous sulfhydryl (SH) groups and alterations in HCl production to the extract's gastroprotective effect were investigated. We also determined the antioxidant activity of the extract and the possible contribution of tannins to the cytoprotective effect. The extract and carbenoxolone protected the gastric mucosa from ethanol/HCl-induced ulcers, and the former also decreased HCl production. The blockage of SH groups but not the inhibition of NO synthesis abolished the gastroprotective action of the extract. Tannins are present in the extract, which was analyzed by matrix assisted laser desorption/ionization (MALDI); the tannins identified by fragmentation pattern (MS/MS) were condensed type-B, coupled up to eleven flavan-3-ol units and were predominantly procyanidin and prodelphinidin units. Partial removal of tannins from the extract abolished the cytoprotective actions of the extract. The extract exhibits free-radical-scavenging activity in vitro, and the extract/FeCl3 sequence stained gastric surface epithelial cells dark-gray. Therefore, E. dysenterica leaf extract has gastroprotective effects that appear to be linked to the inhibition of HCl production, the antioxidant activity and the endogenous SH-containing compounds. These pleiotropic actions appear to be dependent on the condensed tannins contained in the extract, which bind to mucins in the gastric mucosa forming a protective coating against damaging agents. Our study highlights the biopharmaceutical potential of E. dysenterica.

Host genetic factors respond to pathogenic step-specific virulence factors of Helicobacter pylori in gastric carcinogenesis

The interindividual differences in risk of Helicobacter pylori (H. pylori)-associated gastric cancer involve significant heterogeneities of both host genetics and H. pylori strains. Several recent studies proposed a distinct sequence for H. pylori exerting its virulence in the host stomach: (i) adhering to and colonizing the surface of gastric epithelial cells, (ii) evading and attenuating the host defense, and (iii) invading and damaging the gastric mucosa. This review focuses on several key issues that still need to be clarified, such as which virulence factors of H. pylori are involved in the three pathogenic steps, which host genes respond to the step-specific virulence factors, and whether and/or how the corresponding host genetic variations influence the risk of gastric carcinogenesis. Urease, BabA and SabA in the adhesion-step, PGN and LPS in the immune evasion-step, and CagA, VacA and Tipα in the mucosal damage-step were documented to play an important role in step-specific pathogenicity of H. pylori infection. There is evidence further supporting a role of potentially functional polymorphisms of host genes directly responding to these pathogenic step-specific virulence factors in the susceptibility of gastric carcinogenesis, especially for urease-interacting HLA class II genes, BabA-interacting MUC1, PGN-interacting NOD1, LPS-interacting TLR4, and CagA-interacting PTPN11 and CDH1. With the continuous improvement of understanding the genetic profile of H. pylori-associated gastric carcinogenesis, a person at increased risk for gastric cancer may benefit from several aspects of efforts: (i) prevent H. pylori infection with a vaccine targeting certain step-specific virulence factor; (ii) eradicate H. pylori infection by blocking step-specific psychopathological characteristics of virulence factors; and (iii) adjust host physiological function to resist the carcinogenic role of step-specific virulence factors or interrupt the cellular signal transduction of the interplay between H. pylori and host in each pathogenic step, especially for the subjects with precancerous lesions in the stomach.

Alterations in Helicobacter pylori Triggered by Contact with Gastric Epithelial Cells

Helicobacter pylori lives within the mucus layer of the human stomach, in close proximity to gastric epithelial cells. While a great deal is known about the effects of H. pylori on human cells and the specific bacterial products that mediate these effects, relatively little work has been done to investigate alterations in H. pylori that may be triggered by bacterial contact with human cells. In this review, we discuss the spectrum of changes in bacterial physiology and morphology that occur when H. pylori is in contact with gastric epithelial cells. Several studies have reported that cell contact causes alterations in H. pylori gene transcription. In addition, H. pylori contact with gastric epithelial cells promotes the formation of pilus-like structures at the bacteria–host cell interface. The formation of these structures requires multiple genes in the cag pathogenicity island, and these structures are proposed to have an important role in the type IV secretion system-dependent process through which CagA enters host cells. Finally, H. pylori contact with epithelial cells can promote bacterial replication and the formation of microcolonies, phenomena that are facilitated by the acquisition of iron and other nutrients from infected cells. In summary, the gastric epithelial cell surface represents an important niche for H. pylori, and upon entry into this niche, the bacteria alter their behavior in a manner that optimizes bacterial proliferation and persistent colonization of the host.

Helicobacter Pylori –Infected Patients

Background: The role of Helicobacter pylori on gastric carcinogenesis is still unclear but it is considered to predispose carriers to gastric cancer.Objective: The aim of this study is to investigate the relationship between the extent of DNA damage of normal gastric epithelial cells and H. Pylori positive & negative gastritis according to the histological diagnosis.Methods: We compared the percentage of cometed cells on the surface of gastric epithelial cells to the cells beneath gastric mucosal cells by the process of serial incubations times. DNA damage was evaluated by the alkaline single cell gel electrophoresis (comet assay) for 52 cases ,compared 19 normal individuals with 19 patients of H.Pylori positive & negative gastritis and further 14 mixed cases with different histology grading were tested by comet procedure for detection of the relationship of histological diagnosis with DNA damage (comet percentage).Results: There was a relationship between the comet percentage and the histological diagnosis. Comet percentages in specimens from case with normal histology were significantly higher than comet percentages in specimen from case with H. pylori positive gastritis.Conclusion: There was a significant increase in the percentage of cometed cells on the surface of gastric epithelial cells in both normal and infected H. pylori cells compared to the same specimen in the subsequent gastric cell layers.

Relationship between the Extent of DNA Damage and Gastritis in Normal and Helicobacter pylori-Infected Patients

Background/AimsThe role of Helicobacter pylori in gastric carcinogenesis is unclear, but H. pylori infection is thought to predispose carriers to gastric cancer. The aim of this study was to investigate the relationship between the extent of DNA damage in normal gastric epithelial cells and H. pylori-positive and -negative gastritis according to histological diagnosis. We also compared the percentage of cometed cells on the surface of the gastric epithelial cells to the percentage beneath the gastric mucosal cells using serial incubations times.MethodsThe comet assay is a rapid, efficient and reproducible measure of DNA damage in single cell and it was used in this study. DNA damage was evaluated in 52 cases using alkaline single cell gel electrophoresis (comet assay). Comparisons were made between 19 normal individuals, 19 patients with H. pylori-positive and -negative gastritis and 14 mixed cases with different histology gradings to determine if there was a relationship between histological diagnosis and DNA damage (comet percentage).ResultsThe comet percentages in specimens from cases with normal histology were significantly higher than the comet percentages in specimens from cases with H. pylori-positive gastritis. In addition, there was a significant increase in the percentage of cometed cells on the surface of gastric epithelial cells in both normal and H. pylori-infected cells compared to the subsequent gastric cell layers of the same specimen.ConclusionsA relationship between the comet percentage and the histological diagnosis was observed.

Many ways of communication: from Helicobacter pylori adherence to death, disruption, migration and escape

Many ways of communication: from Helicobacter pylori adherence to death, disruption, migration and escape

Effect of ezrin knockdown on the architecture of gastric epithelia

Ezrin, an adaptor protein that cross‐links plasma membrane‐associated proteins with actin cytoskeleton, is highly concentrated on the apical surface of many epithelial cell types especially in microvilli in small intestines and stomachs. In stomachs, ezrin is predominantly expressed on apical canalicular membrane of parietal cells. The ezrin knockdown (Vil2kd/kd) mice showed achlorhydria due to the impairment of membrane fusion of tubulovesicles with apical membrane. Here, we newly showed the involvement of ezrin in the architecture of gastric glands using the Vil2kd/kd mice. The Vil2kd/kd mice showed hypergastrinemia and hyperplasia of gastric surface epithelial cells. Atrophy was observed in the gastric glands with the number of parietal cells and chief cells being decreased, and the number of mucus neck cells being increased. The expression level of gastric proton pump was significantly decreased whereas the expression level of chloride channel CFTR was increased. These results demonstrate that ezrin is involved in the development of gastric epithelial cells and expression of transport proteins involved in gastric acid secretion.

AHNAK expression and subcellular localization in gastric surface epithelial cells

We have previously demonstrated the expression of AHNAK protein in normal human organ donor stomach tissues. In order to identify the specific cells that express AHNAK in human stomach, we performed immunohistochemistry. We evaluated the subcellular localization and movement of AHNAK protein by immunohistochemistry, sucrose density gradient centrifugation, and Western blot analysis using specific AHNAK and subcellular marker antibodies. AHNAK immunoreactivity was localized to PAS, Alcian Blue, MUC5A positive gastric surface epithelial cells in normal human organ donor stomachs. Normal rat gastric mucosa (RGM1) cells demonstrated strong cytoplasmic staining for AHNAK. AHNAK protein was found predominately in the cytoplasmic fraction under standard culture conditions of RGM1 cells. AHNAK is often described as a nuclear phosphoprotein that translocates to the plasma membrane where it is involved in signal transduction, cell membrane differentiation, and repair. Further investigation and understanding of the potential recruitment of AHNAK to the plasma membrane may allow for novel strategies to regulate specific signaling cascades and induce membrane repair in gastric surface epithelial cells. This research was supported by an American Heart Association Predoctoral Fellowship and a Veterans Affairs Merit grant.