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Integrin but not CEACAM receptors are dispensable for Helicobacter pylori CagA translocation.

ABSTRACT: Translocation of the Helicobacter pylori (Hp) cytotoxin-associated gene A (CagA) effector protein via the cag-Type IV Secretion System (cag-T4SS) into host cells is a hallmark of infection with Hp and a major risk factor for severe gastric diseases, including gastric cancer. To mediate the injection of CagA, Hp uses a membrane-embedded syringe-like molecular apparatus extended by an external pilus-like rod structure that binds host cell surface integrin heterodimers. It is still largely unclear how the interaction of the cag-T4SS finally mediates translocation of the CagA protein into the cell cytoplasm. Recently certain carcinoembryonic antigen-related cell adhesion molecules (CEACAMs), acting as receptor for the Hp outer membrane adhesin HopQ, have been identified to be involved in the process of CagA host cell injection. Here, we applied the CRISPR/Cas9-knockout technology to generate defined human gastric AGS and KatoIII integrin knockout cell lines. Although confocal laser scanning microscopy revealed a co-localization of Hp and ?1 integrin heterodimers on gastric epithelial cells, Hp infection studies using the quantitative and highly sensitive Hp ?-lactamase reporter system clearly show that neither ?1 integrin heterodimers (?1?1, ?2?1 or ?5?1), nor any other ?? integrin heterodimers on the cell surface are essential for CagA translocation. In contrast, deletion of the HopQ adhesin in Hp, or the simultaneous knockout of the receptors CEACAM1, CEACAM5 and CEACAM6 in KatoIII cells abolished CagA injection nearly completely, although bacterial binding was only reduced to 50%. These data provide genetic evidence that the cag-T4SS-mediated interaction of Hp with cell surface integrins on human gastric epithelial cells is not essential for CagA translocation, but interaction of Hp with CEACAM receptors is facilitating CagA translocation by the cag-T4SS of this important microbe.

SUBMITTER: Zhao Q

PROVIDER: S-EPMC6231679 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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Integrin but not CEACAM receptors are dispensable for Helicobacter pylori CagA translocation.

Zhao Qing Q Busch Benjamin B Jiménez-Soto Luisa Fernanda LF Ishikawa-Ankerhold Hellen H Massberg Steffen S Terradot Laurent L Fischer Wolfgang W Haas Rainer R

PLoS pathogens 20181026 10

Translocation of the Helicobacter pylori (Hp) cytotoxin-associated gene A (CagA) effector protein via the cag-Type IV Secretion System (cag-T4SS) into host cells is a hallmark of infection with Hp and a major risk factor for severe gastric diseases, including gastric cancer. To mediate the injection of CagA, Hp uses a membrane-embedded syringe-like molecular apparatus extended by an external pilus-like rod structure that binds host cell surface integrin heterodimers. It is still largely unclear ...[more]

PMID: 30365569

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Project description:Background:Helicobacter pylori typically colonizes the human stomach, but it can occasionally be detected in the oral cavity of infected persons. Clinical outcome as a result of gastric colonization depends on presence of the pathogenicity island cagPAI that encodes a type-IV secretion system (T4SS) for translocation of the effector protein CagA and ADP-heptose. Upon injection into target cells, CagA is phosphorylated, which can be demonstrated by in vitro infection of the gastric epithelial cell line AGS, resulting in cell elongation. Here we investigated whether H. pylori can exert these responses during interaction with cells from the oral epithelium. To this purpose, three oral epithelial cell lines, HN, CAL-27 and BHY, were infected with various virulent wild-type H. pylori strains, and CagA delivery and ADP-heptose-mediated pro-inflammatory responses were monitored. Results:All three oral cell lines were resistant to elongation upon infection, despite similar bacterial binding capabilities. Moreover, T4SS-dependent CagA injection was absent. Resistance to CagA delivery was shown to be due to absence of CEACAM expression in these cell lines, while these surface molecules have recently been recognized as H. pylori T4SS receptors. Lack of CEACAM expression in HN, CAL-27 and BHY cells was overcome by genetic introduction of either CEACAM1, CEACAM5, or CEACAM6, which in each of the cell lines was proven sufficient to facilitate CagA delivery and phosphorylation upon H. pylori infection to levels similar to those observed with the gastric AGS cells. Pro-inflammatory responses, as measured by interleukin-8 ELISA, were induced to high levels in each cell line and CEACAM-independent. Conclusions:These results show that lack of CEACAM receptors on the surface of the oral epithelial cells was responsible for resistance to H. pylori CagA-dependent pathogenic activities, and confirms the important role for the T4SS-dependent interaction of these receptors with H. pylori in the gastric epithelium.

Dataset Information

Integrin but not CEACAM receptors are dispensable for Helicobacter pylori CagA translocation.

Publications

Integrin but not CEACAM receptors are dispensable for Helicobacter pylori CagA translocation.

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