scholarly journals Helicobacter pylori CagA Induces Cortactin Y-470 Phosphorylation-Dependent Gastric Epithelial Cell Scattering via Abl, Vav2 and Rac1 Activation

Cancers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 4241
Author(s):  
Nicole Tegtmeyer ◽  
Aileen Harrer ◽  
Klemens Rottner ◽  
Steffen Backert
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cell ◽  
Cell Motility ◽  
Sh2 Domain ◽  
Small Gtpase ◽  
Gastric Epithelial Cell ◽  
Gastric Epithelium ◽  
Actin Binding ◽  
Cell Scattering ◽  
H Pylori

The pathogen Helicobacter pylori is the first reported bacterial type-1 carcinogen playing a role in the development of human malignancies, including gastric adenocarcinoma. Cancer cell motility is an important process in this scenario, however, the molecular mechanisms are still not fully understood. Here, we demonstrate that H. pylori subverts the actin-binding protein cortactin through its type-IV secretion system and injected oncoprotein CagA, e.g., by inducing tyrosine phosphorylation of cortactin at Y-470, which triggers gastric epithelial cell scattering and motility. During infection of AGS cells, cortactin was discovered to undergo tyrosine dephosphorylation at residues Y-421 and Y-486, which is mediated through inactivation of Src kinase. However, H. pylori also profoundly activates tyrosine kinase Abl, which simultaneously phosphorylates cortactin at Y-470. Phosphorylated cortactin interacts with the SH2-domain of Vav2, a guanine nucleotide exchange factor for the Rho-family of GTPases. The cortactin/Vav2 complex then stimulates a previously unrecognized activation cascade including the small GTPase Rac1, to effect actin rearrangements and cell scattering. We hypothesize that injected CagA targets cortactin to locally open the gastric epithelium in order to get access to certain nutrients. This may disturb the cellular barrier functions, likely contributing to the induction of cell motility, which is important in gastric cancer development.

scholarly journals Effect of Astaxanthin on Activation of Autophagy and Inhibition of Apoptosis in Helicobacter pylori-Infected Gastric Epithelial Cell Line AGS

Nutrients ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1750 ◽  
Author(s):  
Hanbit Lee ◽  
Joo Weon Lim ◽  
Hyeyoung Kim
Keyword(s):  
Helicobacter Pylori ◽  
Protein Kinase ◽  
Epithelial Cell ◽  
Cell Line ◽  
Gastric Epithelial Cell ◽  
Epithelial Cell Line ◽  
Ags Cells ◽  
Compound C ◽  
H Pylori ◽  
Induced Apoptosis

Helicobacter pylori (H. pylori) infection leads to the massive apoptosis of the gastric epithelial cells, causing gastric ulcers, gastritis, and gastric adenocarcinoma. Autophagy is a cellular recycling process that plays important roles in cell death decisions and can protect cells by preventing apoptosis. Upon the induction of autophagy, the level of the autophagy substrate p62 is reduced and the autophagy-related ratio of microtubule-associated proteins 1A/1B light chain 3B (LC3B)-II/LC3B-I is heightened. AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) are involved in the regulation of autophagy. Astaxanthin (AST) is a potent anti-oxidant that plays anti-inflammatory and anti-cancer roles in various cells. In the present study, we examined whether AST inhibits H. pylori-induced apoptosis through AMPK-mediated autophagy in the human gastric epithelial cell line AGS (adenocarcinoma gastric) in vitro. In this study, H. pylori induced apoptosis. Compound C, an AMPK inhibitor, enhanced the H. pylori-induced apoptosis of AGS cells. In contrast, metformin, an AMPK activator, suppressed H. pylori-induced apoptosis, showing that AMPK activation inhibits H. pylori-induced apoptosis. AST inhibited H. pylori-induced apoptosis by increasing the phosphorylation of AMPK and decreasing the phosphorylation of RAC-alpha serine/threonine-protein kinase (Akt) and mTOR in H. pylori-stimulated cells. The number of LC3B puncta in H. pylori-stimulated cells increased with AST. These results suggest that AST suppresses the H. pylori-induced apoptosis of AGS cells by inducing autophagy through the activation of AMPK and the downregulation of its downstream target, mTOR. In conclusion, AST may inhibit gastric diseases associated with H. pylori infection by increasing autophagy through the activation of the AMPK pathway.

scholarly journals Mechanisms of interacting Helicobacter pylori with gastric mucosal epithelium. II. A reaction of gastric epithelium on Helicobacter pylori colonization and persistence

2019 ◽  
Vol 9 (2) ◽  
pp. 253-261
Author(s):  
O. K. Pozdeev ◽  
A. O. Pozdeeva ◽  
Yu. V. Valeeva ◽  
P. E. Gulyaev ◽  
A. N. Savinova
Keyword(s):  
Helicobacter Pylori ◽  
T Cell ◽  
Epithelial Cell ◽  
Gastric Mucosa ◽  
Mapk Pathway ◽  
Bacterial Colonization ◽  
Gastric Epithelium ◽  
T Cell Subsets ◽  
H Pylori ◽  
Apoptotic Factors

Gastric and duodenal recurrent inflammatory diseases have a high prevalence, but the role played by microbes in its development remained unclear. However, the data published in 1983 by Marshall and Warren about isolatingHelicobacter pylorifrom the stomach mucosa of the patient with gastritis and proposing relevant cultivation methods was the turning point in investigating etiology of the upper digestive tract inflammatory disorders. Moreover, it was shown that the majority ofH. pylorispp. are found within the gastric lumen upon colonization, whereas around 20% of them are attached to the epithelial cells in the stomach. In addition, effects of interacting H. pylori with gastric epithelium and activation of some defense mechanisms due to bacterial colonization and spreading were analyzed. It was found that along with triggering pro-inflammatory response induced by proteins VacA as well as phosphorylated/unphosphorylated CagA, wherein the latter is able to induce a set of protective reactionsH. pyloridisrupts intercellular contacts, affects epithelial cell polarity and proliferation, and activates SHP-2 phosphatase resulting in emerging diverse types of cellular responses. The activation mechanisms for the mitogen-activated protein kinase (MAPK) pathway were discussed. The ability ofH. pylorito regulate apoptosis, particularly via its suppression, by expressing ERK kinase and protein MCL1 facilitating bacterial survival in the gastric mucosa as well as beneficial effects related to bacterial circulation on gastric epithelial cell survival elicited by anti-apoptotic factors were also examined. Of note, persistence of H. pylori are mainly determined by activating transcriptional factors including NF-κB, NFAT, SRF, T-cell lymphoid enhancing factor (TCF/LEF), regulating activity of MCL1 protein, in turn, being one of the main anti-apoptotic factors, as well as induced production of the migration inhibitory factor (MIF). The role of VacA cytotoxin in triggering epithelial cell apoptosis via caspase-mediated pathways was also considered. Infection withH. pyloriis accompanied by release of proinflammatory cytokine cocktail detected bothin vitroandin vivo. In particular, bacterial urease activating transcriptional factor NF-κB was shown to play a crucial role in inducing cytokine production. Moreover, such signaling pathways may be activated afterH. pyloriis attached to the cognate receptor in the gastric epithelial surface by interacting with CD74 and MHC class II molecules. Finally, a role for various CD4+T cell subsets, particularly type 17 T helper cells (Th17) in inducing immune response against H. pylori antigens in gastric mucosa was revealed were also discussed. 

scholarly journals Cortactin Promotes Effective AGS Cell Scattering by Helicobacter pylori CagA, but Not Cellular Vacuolization and Apoptosis Induced by the Vacuolating Cytotoxin VacA

Pathogens ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 3
Author(s):  
Irshad Sharafutdinov ◽  
Jakob Knorr ◽  
Delara Soltan Esmaeili ◽  
Steffen Backert ◽  
Nicole Tegtmeyer
Keyword(s):  
Helicobacter Pylori ◽  
Cell Movement ◽  
Actin Binding ◽  
Knockout Mutant ◽  
Vacuolating Cytotoxin ◽  
Cell Functions ◽  
Cell Scattering ◽  
Induction Of Apoptosis ◽  
H Pylori ◽  
Cytoskeletal Rearrangements

Cortactin is an actin-binding protein and actin-nucleation promoting factor regulating cytoskeletal rearrangements in eukaryotes. Helicobacter pylori is a gastric pathogen that exploits cortactin to its own benefit. During infection of gastric epithelial cells, H. pylori hijacks multiple cellular signaling pathways, leading to the disruption of key cell functions. Two bacterial virulence factors play important roles in this scenario, the vacuolating cytotoxin VacA and the translocated effector protein CagA of the cag type IV secretion system (T4SS). Specifically, by overruling the phosphorylation status of cortactin, H. pylori alternates the activity of molecular interaction partners of this important protein, thereby manipulating the performance of cytoskeletal rearrangements, endosomal trafficking and cell movement. Based on shRNA knockdown and other studies, it was previously reported that VacA utilizes cortactin for its cellular uptake, intracellular travel and induction of apoptosis by a mitochondria-dependent mechanism, while CagA induces cell scattering, motility and elongation. To investigate the role of cortactin in these phenotypes in more detail, we produced a complete knockout mutant of cortactin in the gastric adenocarcinoma cell line AGS by CRISPR-Cas9. These cells were infected with H. pylori wild-type or various isogenic mutant strains. Unexpectedly, cortactin deficiency did not prevent the uptake and formation of VacA-dependent vacuoles, nor the induction of apoptosis by internalized VacA, while the induction of T4SS- and CagA-dependent AGS cell movement and elongation were strongly reduced. Thus, we provide evidence that cortactin is required for the function of internalized CagA, but not VacA.

scholarly journals Identification of two new Helicobacter pylori surface proteins involved in attachment to epithelial cell lines

2005 ◽  
Vol 54 (5) ◽  
pp. 427-434 ◽  
Author(s):  
Sebastian Rubinsztein-Dunlop ◽  
Bruno Guy ◽  
Ling Lissolo ◽  
Hans Fischer
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Lines ◽  
Gastric Epithelium ◽  
Cellular Interactions ◽  
Bacterial Adhesins ◽  
Epithelial Cell Lines ◽  
H Pylori ◽  
Adhesive Proteins

Helicobacter pylori causes the development of gastritis, gastric ulcers and adenocarcinomas in humans. The establishment of infection is influenced by adherence to the gastric epithelium, and several bacterial adhesins and host cell receptors have been identified. H. pylori recognize the Lewisb receptor through the BabA adhesin but also readily adhere to epithelia in the absence of the Lewisb epitope, demonstrating the relevance of additional adhesive interactions. This study presents a novel method of identifying bacterial adhesins. Nickel beads were coated with H. pylori-derived, recombinantly expressed ORF proteins, and epithelial cells from the human stomach, intestine or urinary tract were allowed to adhere to those beads. The binding of epithelial cells to the protein-coated nickel beads was confirmed by electron microscopy or flow cytometry using antibodies directed towards the His-tags. Among the five ORFs tested, two new adhesive proteins (HP1188 and HP1430) were identified. Both were expressed on the surface of virulent H. pylori, with the HP1188 protein being most abundant. The purified HP1188 and HP1430 proteins bound more strongly to gastric than to other epithelial cell lines, suggesting that they may be involved in the colonization of the human gastric mucosa. In conclusion, this method facilitates the identification of ORFs of microbial origin involved in cellular interactions such as adherence.

scholarly journals Enhanced Disease Severity in Helicobacter pylori-Infected Mice Deficient in Fas Signaling

2002 ◽  
Vol 70 (5) ◽  
pp. 2591-2597 ◽  
Author(s):  
Nicola L. Jones ◽  
Andrew S. Day ◽  
Hilary Jennings ◽  
Patrick T. Shannon ◽  
Esther Galindo-Mata ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cell ◽  
Cell Apoptosis ◽  
Fas Ligand ◽  
Bacterial Colonization ◽  
Gastric Epithelial Cell ◽  
Epithelial Cell Apoptosis ◽  
Fas Signaling ◽  
Ifn Γ ◽  
H Pylori

ABSTRACT Recent evidence suggests that immune-mediated gastric epithelial cell apoptosis through Fas-Fas ligand interactions participates in Helicobacter pylori disease pathogenesis. To define the role of Fas signaling in vivo, H. pylori strain SS1 infection in C57BL/6 mice was compared to that in mice deficient in the Fas ligand (gld). gld mice had a degree of gastritis similar to that of C57BL/6 mice after 6 weeks (gastritis score, 5.2 ± 0.6 [mean ± standard error] versus 3.5 ± 0.8) and 12 weeks (4.0 ± 0.7 versus 3.4 ± 0.5) of infection. Bacterial colonization was comparable in each group of mice at 12 weeks of infection (2.1 ± 0.3 versus 1.6 ± 0.3 for gld and C57BL/6, respectively; the difference is not significant). Sixty-seven percent of H. pylori-infected gld mice displayed atrophic changes in the gastric mucosa, compared with 37% of infected C57BL/6 mice, at 12 weeks. In addition, atrophic changes were more severe in H. pylori-infected gld mice (P < 0.05). Splenocytes isolated from H. pylori-infected C57BL/6 mice had a twofold increase in production of the Th1 cytokine gamma interferon (IFN-γ) in response to H. pylori antigens at both 6 and 12 weeks compared to controls (143 ± 65 versus 69 ±26 pg/ml and 336 ± 73 versus 172 ± 60, respectively). In contrast, there was a lack of detectable IFN-γ in gld mice infected with the bacterium. H. pylori-infected C57BL/6 mice had increased epithelial cell apoptosis compared with sham-infected C57BL/6 mice (35.0 ± 8.9 versus 12.3 ± 6.9; P < 0.05). Epithelial cell apoptosis did not differ between H. pylori-infected and control gld mice (5.2 ± 1.6 versus 6.5 ± 2.9 [not significant]). These data demonstrate that mice with mutations in the Fas ligand develop more severe premalignant mucosal changes in response to infection with H. pylori in association with both an impaired gastric epithelial cell apoptotic response and IFN-γ production. The Fas death pathway modulates disease pathophysiology following murine infection with H. pylori. Deregulation of the Fas pathway could be involved in the transition from gastritis to gastric cancers during H. pylori infection.

scholarly journals Helicobacter pylori Infection Induces Interleukin-8 Receptor Expression in the Human Gastric Epithelium

2003 ◽  
Vol 71 (6) ◽  
pp. 3357-3360 ◽  
Author(s):  
Fredrik Bäckhed ◽  
Elisabeth Torstensson ◽  
Delphine Seguin ◽  
Agneta Richter-Dahlfors ◽  
Bachra Rokbi
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Gastric Biopsy ◽  
Receptor Expression ◽  
Interleukin 8 ◽  
Gastric Epithelium ◽  
Epithelial Cell Line ◽  
Gastric Epithelial Cells ◽  
H Pylori

ABSTRACT The gastric pathogen Helicobacter pylori is known to activate multiple proinflammatory signaling pathways in epithelial cells. In this study, we addressed the question of whether expression of the interleukin-8 receptors IL-8RA (CXCR1) and IL-8RB (CXCR2) is upregulated in H. pylori-infected human gastric biopsy samples. Biopsy samples from patients infected with H. pylori strains harboring the cag pathogenicity island (PAI) expressed larger amounts of both receptors. In addition, IL-8RB expression was induced in the gastric epithelial cell line AGS upon infection with a clinical isolate containing the cag PAI, while a strain lacking the cag PAI did not. Our finding suggests that gastric epithelial cells express IL-8R in response to H. pylori infection.

scholarly journals Helicobacter pylori VacA Toxin Promotes Bacterial Intracellular Survival in Gastric Epithelial Cells

2006 ◽  
Vol 74 (12) ◽  
pp. 6599-6614 ◽  
Author(s):  
M. R. Terebiznik ◽  
C. L. Vazquez ◽  
K. Torbicki ◽  
D. Banks ◽  
T. Wang ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Small Gtpase ◽  
Host Cells ◽  
Gastric Epithelium ◽  
Current Evidence ◽  
Causative Role ◽  
Peptic Ulcers ◽  
Ags Cells ◽  
H Pylori

ABSTRACT Helicobacter pylori colonizes the gastric epithelium of at least 50% of the world's human population, playing a causative role in the development of chronic gastritis, peptic ulcers, and gastric adenocarcinoma. Current evidence indicates that H. pylori can invade epithelial cells in the gastric mucosa. However, relatively little is known about the biology of H. pylori invasion and survival in host cells. Here, we analyze both the nature of and the mechanisms responsible for the formation of H. pylori's intracellular niche. We show that in AGS cells infected with H. pylori, bacterium-containing vacuoles originate through the fusion of late endocytic organelles. This process is mediated by the VacA-dependent retention of the small GTPase Rab7. In addition, functional interactions between Rab7 and its downstream effector, Rab-interacting lysosomal protein (RILP), are necessary for the formation of the bacterial compartment since expression of mutant forms of RILP or Rab7 that fail to bind each other impaired the formation of this unique bacterial niche. Moreover, the VacA-mediated sequestration of active Rab7 disrupts the full maturation of vacuoles as assessed by the lack of both colocalization with cathepsin D and degradation of internalized cargo in the H. pylori-containing vacuole. Based on these findings, we propose that the VacA-dependent isolation of the H. pylori-containing vacuole from bactericidal components of the lysosomal pathway promotes bacterial survival and contributes to the persistence of infection.

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