scholarly journals Helicobacter pylori Exploits Cholesterol-Rich Microdomains for Induction of NF-κB-Dependent Responses and Peptidoglycan Delivery in Epithelial Cells

2010 ◽  
Vol 78 (11) ◽  
pp. 4523-4531 ◽  
Author(s):  
Melanie L. Hutton ◽  
Maria Kaparakis-Liaskos ◽  
Lorinda Turner ◽  
Ana Cardona ◽  
Terry Kwok ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Host Cell ◽  
Severe Disease ◽  
Host Cells ◽  
Type Iv ◽  
Increased Risk ◽  
Proinflammatory Responses ◽  
H Pylori ◽  
Cytoskeletal Rearrangements

ABSTRACT Infection with Helicobacter pylori cag pathogenicity island (cagPAI)-positive strains is associated with more destructive tissue damage and an increased risk of severe disease. The cagPAI encodes a type IV secretion system (TFSS) that delivers the bacterial effector molecules CagA and peptidoglycan into the host cell cytoplasm, thereby inducing responses in host cells. It was previously shown that interactions between CagL, present on the TFSS pilus, and host α5β1 integrin molecules were critical for CagA translocation and the induction of cytoskeletal rearrangements in epithelial cells. As the α5β1 integrin is found in cholesterol-rich microdomains (known as lipid rafts), we hypothesized that these domains may also be involved in the induction of proinflammatory responses mediated by NOD1 recognition of H. pylori peptidoglycan. Indeed, not only did methyl-β-cyclodextrin depletion of cholesterol from cultured epithelial cells have a significant effect on the levels of NF-κB and interleukin-8 (IL-8) responses induced by H. pylori bacteria with an intact TFSS (P < 0.05), but it also interfered with TFSS-mediated peptidoglycan delivery to cells. Both of these effects could be restored by cholesterol replenishment of the cells. Furthermore, we demonstrated for the first time the involvement of α5β1 integrin in the induction of proinflammatory responses by H. pylori. Taking the results together, we propose that α5β1 integrin, which is associated with cholesterol-rich microdomains at the host cell surface, is required for NOD1 recognition of peptidoglycan and subsequent induction of NF-κB-dependent responses to H. pylori. These data implicate cholesterol-rich microdomains as a novel platform for TFSS-dependent delivery of bacterial products to cytosolic pathogen recognition molecules.

scholarly journals The Helicobacter pylori Autotransporter ImaA Tempers the Bacterium's Interaction with α5β1 Integrin

2016 ◽  
Vol 85 (1) ◽  
Author(s):  
William E. Sause ◽  
Daniela Keilberg ◽  
Soufiane Aboulhouda ◽  
Karen M. Ottemann
Keyword(s):  
Helicobacter Pylori ◽  
Host Cell ◽  
Type Iv Secretion ◽  
Host Cells ◽  
Wild Type ◽  
Content Type ◽  
Type Iv ◽  
H Pylori ◽  
Α5β1 Integrin ◽  
Cell Interface

ABSTRACT The human pathogen Helicobacter pylori uses the host receptor α5β1 integrin to trigger inflammation in host cells via its cag pathogenicity island (cag PAI) type IV secretion system (T4SS). Here, we report that the H. pylori ImaA protein (HP0289) decreases the action of the cag PAI T4SS via tempering the bacterium's interaction with α5β1 integrin. Previously, imaA-null mutants were found to induce an elevated inflammatory response that was dependent on the cag PAI T4SS; here we extend those findings to show that the elevated response is independent of the CagA effector protein. To understand how ImaA could be affecting cag PAI T4SS activity at the host cell interface, we utilized the Phyre structural threading program and found that ImaA has a region with remote homology to bacterial integrin-binding proteins. This region was required for ImaA function. Unexpectedly, we observed that imaA mutants bound higher levels of α5β1 integrin than wild-type H. pylori, an outcome that required the predicted integrin-binding homology region of ImaA. Lastly, we report that ImaA directly affected the amount of host cell β1 integrin but not other cellular integrins. Our results thus suggest a model in which H. pylori employs ImaA to regulate interactions between integrin and the T4SS and thus alter the host inflammatory strength.

scholarly journals An Overview of Helicobacter pylori Survival Tactics in the Hostile Human Stomach Environment

2021 ◽  
Vol 9 (12) ◽  
pp. 2502
Author(s):  
Yi Ying Cheok ◽  
Chalystha Yie Qin Lee ◽  
Heng Choon Cheong ◽  
Jamuna Vadivelu ◽  
Chung Yeng Looi ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Vaccine Development ◽  
Outer Membrane Proteins ◽  
Host Cells ◽  
Host Immune System ◽  
Host Interaction ◽  
Type Iv ◽  
H Pylori

Helicobacter pylori is well established as a causative agent for gastritis, peptic ulcer, and gastric cancer. Armed with various inimitable virulence factors, this Gram-negative bacterium is one of few microorganisms that is capable of circumventing the harsh environment of the stomach. The unique spiral structure, flagella, and outer membrane proteins accelerate H. pylori movement within the viscous gastric mucosal layers while facilitating its attachment to the epithelial cells. Furthermore, secretion of urease from H. pylori eases the acidic pH within the stomach, thus creating a niche for bacteria survival and replication. Upon gaining a foothold in the gastric epithelial lining, bacterial protein CagA is injected into host cells through a type IV secretion system (T4SS), which together with VacA, damage the gastric epithelial cells. H. pylori does not only establishes colonization in the stomach, but also manipulates the host immune system to permit long-term persistence. Prolonged H. pylori infection causes chronic inflammation that precedes gastric cancer. The current review provides a brief outlook on H. pylori survival tactics, bacterial-host interaction and their importance in therapeutic intervention as well as vaccine development.

scholarly journals Complex Cellular Responses of Helicobacter pylori-Colonized Gastric Adenocarcinoma Cells

2011 ◽  
Vol 79 (6) ◽  
pp. 2362-2371 ◽  
Author(s):  
Sabine Schneider ◽  
Gert Carra ◽  
Ugur Sahin ◽  
Benjamin Hoy ◽  
Gabriele Rieder ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Host Cell ◽  
Cell Lines ◽  
Molecular Mechanisms ◽  
Cellular Responses ◽  
Host Cells ◽  
Human Gastric Mucosa ◽  
Content Type ◽  
H Pylori

ABSTRACTHelicobacter pyloriis an important class I carcinogen that persistently infects the human gastric mucosa to induce gastritis, gastric ulceration, and gastric cancer.H. pyloripathogenesis strongly depends on pathogenic factors, such as VacA (vacuolating cytotoxin A) or a specialized type IV secretion system (T4SS), which injects the oncoprotein CagA (cytotoxin-associated gene A product) into the host cell. Since access to primary gastric epithelial cells is limited, many studies on the complex cellular and molecular mechanisms ofH. pyloriwere performed in immortalized epithelial cells originating from individual human adenocarcinomas. The aim of our study was a comparative analysis of 14 different human gastric epithelial cell lines after colonization withH. pylori. We found remarkable differences in host cell morphology, extent of CagA tyrosine phosphorylation, adhesion to host cells, vacuolization, and interleukin-8 (IL-8) secretion. These data might help in the selection of suitable cell lines to study host cell responses toH. pyloriin vitro, and they imply that different host cell factors are involved in the determination ofH. pyloripathogenesis. A better understanding ofH. pylori-directed cellular responses can provide novel and more balanced insights into the molecular mechanisms ofH. pylori-dependent pathogenesisin vivoand may lead to new therapeutic approaches.

scholarly journals The Coupling Protein Cagβ and Its Interaction Partner CagZ Are Required for Type IV Secretion of the Helicobacter pylori CagA Protein

2010 ◽  
Vol 78 (12) ◽  
pp. 5244-5251 ◽  
Author(s):  
Angela Jurik ◽  
Elisabeth Haußer ◽  
Stefan Kutter ◽  
Isabelle Pattis ◽  
Sandra Praßl ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Host Cell ◽  
Protein Interactions ◽  
Translocation Factor ◽  
Type Iv Secretion ◽  
Host Cells ◽  
Protein Protein Interactions ◽  
Type Iv ◽  
Coupling Protein ◽  
Translocation Factors

ABSTRACT Bacterial type IV secretion systems are macromolecule transporters with essential functions for horizontal gene transfer and for symbiotic and pathogenic interactions with eukaryotic host cells. Helicobacter pylori, the causative agent of type B gastritis, peptic ulcers, gastric adenocarcinoma, and mucosa-associated lymphoid tissue (MALT) lymphoma, uses the Cag type IV secretion system to inject its effector protein CagA into gastric cells. This protein translocation results in altered host cell gene expression profiles and cytoskeletal rearrangements, and it has been linked to cancer development. Interactions of CagA with host cell proteins have been studied in great detail, but little is known about the molecular details of CagA recognition as a type IV secretion substrate or of the translocation process. Apart from components of the secretion apparatus, we previously identified several CagA translocation factors that are either required for or support CagA translocation. To identify protein-protein interactions between these translocation factors, we used a yeast two-hybrid approach comprising all cag pathogenicity island genes. Among several other interactions involving translocation factors, we found a strong interaction between the coupling protein homologue Cagβ (HP0524) and the Cag-specific translocation factor CagZ (HP0526). We show that CagZ has a stabilizing effect on Cagβ, and we demonstrate protein-protein interactions between the cytoplasmic part of Cagβ and CagA and between CagZ and Cagβ, using immunoprecipitation and pull-down assays. Together, our data suggest that these interactions represent a substrate-translocation factor complex at the bacterial cytoplasmic membrane.

scholarly journals Cortactin: A Major Cellular Target of the Gastric Carcinogen Helicobacter pylori

Cancers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 159 ◽  
Author(s):  
Irshad Sharafutdinov ◽  
Steffen Backert ◽  
Nicole Tegtmeyer
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Cell Movement ◽  
Cell Types ◽  
Eukaryotic Cell ◽  
Actin Binding ◽  
Gastric Diseases ◽  
Cell Functions ◽  
H Pylori ◽  
Cytoskeletal Rearrangements

Cortactin is an actin binding protein and actin nucleation promoting factor regulating cytoskeletal rearrangements in nearly all eukaryotic cell types. From this perspective, cortactin poses an attractive target for pathogens to manipulate a given host cell to their own benefit. One of the pathogens following this strategy is Helicobacter pylori, which can cause a variety of gastric diseases and has been shown to be the major risk factor for the onset of gastric cancer. During infection of gastric epithelial cells, H. pylori hijacks the cellular kinase signaling pathways, leading to the disruption of key cell functions. 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 actin-cytoskeletal rearrangements and cell movement. In addition, H. pylori utilizes a unique mechanism to activate focal adhesion kinase, which subsequently prevents host epithelial cells from extensive lifting from the extracellular matrix in order to achieve chronic infection in the human stomach.

scholarly journals Analysis of Cell Type-Specific Responses Mediated by the Type IV Secretion System of Helicobacter pylori

2005 ◽  
Vol 73 (8) ◽  
pp. 4643-4652 ◽  
Author(s):  
Bianca Bauer ◽  
Stefan Moese ◽  
Sina Bartfeld ◽  
Thomas F. Meyer ◽  
Matthias Selbach
Keyword(s):  
Helicobacter Pylori ◽  
Host Cell ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Type Iv ◽  
Host Cell Proteins ◽  
Mammalian Cell Lines ◽  
Host Cell Factors ◽  
H Pylori

ABSTRACT Helicobacter pylori persistently infects the human stomach and can cause gastritis, gastric ulceration, and gastric cancer. The type IV secretion system (TFSS) of virulent H. pylori strains translocates the CagA protein, inducing the dephosphorylation of host cell proteins and leading to changes in the morphology or shape of AGS gastric epithelial cells. Furthermore, the TFSS is involved in the induction of proinflammatory cytokines. While the H. pylori genes required for TFSS function have been investigated systematically, little is known about possible host cell factors involved. We infected 19 different mammalian cell lines individually with H. pylori and analyzed CagA translocation, dephosphorylation of host cell proteins, chemokine secretion (interleukin-8 and macrophage inflammatory protein 2), and changes in cellular phenotypes. Our results demonstrate that not only bacterial but also host cell factors determine the cellular response to infection. The identification of such unknown host cell factors will add to our understanding of host-pathogen interactions and might help in the development of new therapeutic strategies.

scholarly journals SHP2-independent tyrosine dephosphorylation of cortactin and vinculin during infection with Helicobacter pylori

2020 ◽  
Vol 10 (1) ◽  
pp. 20-27
Author(s):  
Jakob Knorr ◽  
Steffen Backert ◽  
Nicole Tegtmeyer
Keyword(s):  
Helicobacter Pylori ◽  
Host Cell ◽  
Tyrosine Phosphatase ◽  
Actin Binding ◽  
World Population ◽  
Dependent Manner ◽  
Knockout Mutant ◽  
Ags Cells ◽  
Type Iv ◽  
H Pylori

The gastric pathogen Helicobacter pylori colonizes approximately half of the human world population. The bacterium injects the effector protein cytotoxin associated gene A (CagA) via a type-IV secretion system into host epithelial cells, where the protein becomes phosphorylated at specific EPIYA-motifs by cellular kinases. Inside the host cell, CagA can interact with over 25 different proteins in both phosphorylation-dependent and phosphorylation-independent manners, resulting in manipulation of host-cell signaling pathways. During the course of an H. pylori infection, certain host-cell proteins undergo tyrosine dephosphorylation in a CagA-dependent manner, including the actin-binding proteins cortactin and vinculin. A predominant response of intracellular CagA is the binding and activation of tyrosine phosphatase, the human Src-homology-region-2-domain-containing-phosphatase-2 (SHP2). Here, we considered the possibility that activated SHP2 might be responsible for the dephosphorylation of cortactin and vinculin. To investigate this, phosphatase inhibitor studies were performed. Additionally, a complete knockout mutant of SHP2 in AGS cells was created by CRISPR/Cas9 technology, and these cells were infected with H. pylori. However, neither the presence of an inhibitor nor the inactivation of SHP2 prevented the dephosphorylation of cortactin and vinculin upon CagA delivery. Tyrosine dephosphorylation of these proteins is therefore independent of SHP2 and instead must be caused by another, as yet unidentified, protein tyrosine phosphatase.

scholarly journals T4SS-dependent TLR5 activation by Helicobacter pylori infection

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Suneesh Kumar Pachathundikandi ◽  
Nicole Tegtmeyer ◽  
Isabelle Catherine Arnold ◽  
Judith Lind ◽  
Matthias Neddermann ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Pathogenic Bacteria ◽  
Type Iv Secretion ◽  
Downstream Signaling ◽  
Type Iv ◽  
Efficient Control ◽  
H Pylori ◽  
Highly Virulent

AbstractToll-like receptor TLR5 recognizes a conserved domain, termed D1, that is present in flagellins of several pathogenic bacteria but not in Helicobacter pylori. Highly virulent H. pylori strains possess a type IV secretion system (T4SS) for delivery of virulence factors into gastric epithelial cells. Here, we show that one of the H. pylori T4SS components, protein CagL, can act as a flagellin-independent TLR5 activator. CagL contains a D1-like motif that mediates adherence to TLR5+ epithelial cells, TLR5 activation, and downstream signaling in vitro. TLR5 expression is associated with H. pylori infection and gastric lesions in human biopsies. Using Tlr5-knockout and wild-type mice, we show that TLR5 is important for efficient control of H. pylori infection. Our results indicate that CagL, by activating TLR5, may modulate immune responses to H. pylori.

scholarly journals Tailor-Made Detection of Individual Phosphorylated and Non-Phosphorylated EPIYA-Motifs of Helicobacter pylori Oncoprotein CagA

Cancers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1163 ◽  
Author(s):  
Pachathundikandi ◽  
Gutiérrez-Escobar ◽  
Tegtmeyer
Keyword(s):  
Helicobacter Pylori ◽  
Cross Reactivity ◽  
Host Cells ◽  
Gastric Disease ◽  
Effector Protein ◽  
Sequence Motifs ◽  
Type Iv ◽  
Efficient Detection ◽  
H Pylori ◽  
Epiya Motifs

The gastric pathogen and carcinogen Helicobacter pylori (H. pylori) encodes a type IV secretion system for translocation of the effector protein CagA into host cells. Injected CagA becomes tyrosine-phosphorylated at the five amino acid residue Glutamate-Proline- Isoleucine-Tyrosine-Alanine (EPIYA)-sequence motifs. These phosphorylated EPIYA-sites represent recognition motifs for binding of multiple host factors, which then manipulate signaling pathways to trigger gastric disease. Thus, efficient detection of single phosphorylated EPIYA-motifs in CagA is required. Detection of phospho-CagA is primarily performed using commercial pan-phosphotyrosine antibodies. However, those antibodies were originally generated to recognize many phosphotyrosines in various mammalian proteins and are not optimized for use in bacteria. To address this important limitation, we synthesized 11-mer phospho- and non-phospho-peptides from EPIYA-motifs A, B, and C, and produced three phospho-specific and three non-phospho-specific rabbit polyclonal CagA antibodies. These antibodies specifically recognized the corresponding phosphorylated and non-phosphorylated EPIYA-motifs, while the EPIYA-C antibodies also recognized the related East-Asian EPIYA-D motif. Otherwise, no cross-reactivity of the antibodies among EPIYAs was observed. Western blotting demonstrated that each EPIYA-motif can be predominantly phosphorylated during H. pylori infection. This represents the first complete set of phospho-specific antibodies for an effector protein in bacteria, providing useful tools to gather information for the categorization of CagA phosphorylation, cancer signaling, and gastric disease progression.

scholarly journals Natural Competence Promotes Helicobacter pylori Chronic Infection

2012 ◽  
Vol 81 (1) ◽  
pp. 209-215 ◽  
Author(s):  
Marion S. Dorer ◽  
Ilana E. Cohen ◽  
Tate H. Sessler ◽  
Jutta Fero ◽  
Nina R. Salama
Keyword(s):  
Helicobacter Pylori ◽  
Chronic Infection ◽  
Acute Infection ◽  
Host Cells ◽  
High Rate ◽  
Natural Competence ◽  
Content Type ◽  
Type Iv ◽  
Competence Factor ◽  
H Pylori

Animal models are important tools for studies of human disease, but developing these models is a particular challenge with regard to organisms with restricted host ranges, such as the human stomach pathogenHelicobacter pylori. In most cases,H. pyloriinfects the stomach for many decades before symptoms appear, distinguishing it from many bacterial pathogens that cause acute infection. To model chronic infection in the mouse, a human clinical isolate was selected for its ability to survive for 2 months in the mouse stomach, and the resulting strain, MSD132, colonized the mouse stomach for at least 28 weeks. During selection, thecagYcomponent of the Cag type IV secretion system was mutated, disrupting a key interaction with host cells. Increases in both bacterial persistence and bacterial burden occurred prior to this mutation, and a mixed population ofcagY+andcagYmutant cells was isolated from a single mouse, suggesting that mutations accumulate during selection and that factors in addition to the Cag apparatus are important for murine adaptation. Diversity in both alleles and genes is common inH. pyloristrains, and natural competence mediates a high rate of interstrain genetic exchange. Mutations of the Com apparatus, a membrane DNA transporter, and DprA, a cytosolic competence factor, resulted in reduced persistence, although initial colonization was normal. Thus, exchange of DNA between genetically heterogeneousH. pyloristrains may improve chronic colonization. The strains and methods described here will be important tools for defining both the spectrum of mutations that promote murine adaptation and the genetic program of chronic infection.

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