title: Helicobacter pylori CagA-mediated IL-8 induction in gastric epithelial cells is cholesterol-dependent and requires the C-terminal tyrosine phosphorylation-containing domain.
abstract: Upon infection of the gastric epithelial cells, the Helicobacter pylori cytotoxin-associated gene A (CagA) virulence protein is injected into the epithelial cells via the type IV secretion system (TFSS), which is dependent on cholesterol. Translocated CagA is targeted by the membrane-recruited c-Src family kinases in which a tyrosine residue in the Glu-Pro-Ile-Tyr-Ala (EPIYA)-repeat region, which can be phosphorylated, induces cellular responses, including interleukin-8 (IL-8) secretion and hummingbird phenotype formation. In this study, we explored the role of EPIYA-containing C-terminal domain (CTD) in CagA tethering to the membrane lipid rafts and in IL-8 activity. We found that disruption of the lipid rafts reduced the level of CagA translocation/phosphorylation as well as CagA-mediated IL-8 secretion. By CagA truncated mutagenesis, we identified that the CTD, rather than the N-terminal domain, was responsible for CagA tethering to the plasma membrane and association with detergent-resistant membranes, leading to CagA-induced IL-8 promoter activity. Our results suggest that CagA CTD-containing EPIYAs directly interact with cholesterol-rich microdomains that induce efficient IL-8 secretion in the epithelial cells.
authors.affiliation: Graduate Institute of Basic and Clinical Medical Science, School of Medicine, China Medical University, Taichung, Taiwan.
authors.forename: Chih-Ho
authors.initials: CH
authors.lastname: Lai
authors.forename: Hung-Jung
authors.initials: HJ
authors.lastname: Wang
authors.forename: Yun-Chieh
authors.initials: YC
authors.lastname: Chang
authors.forename: Wan-Chen
authors.initials: WC
authors.lastname: Hsieh
authors.forename: Hwai-Jeng
authors.initials: HJ
authors.lastname: Lin
authors.forename: Chih-Hsin
authors.initials: CH
authors.lastname: Tang
authors.forename: Jim Jinn-Chyuan
authors.initials: JJ
authors.lastname: Sheu
authors.forename: Chun-Jung
authors.initials: CJ
authors.lastname: Lin
authors.forename: Mei-Shiang
authors.initials: MS
authors.lastname: Yang
authors.forename: Shu-Fen
authors.initials: SF
authors.lastname: Tseng
authors.forename: Wen-Ching
authors.initials: WC
authors.lastname: Wang
mesh_terms: D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D004847:Epithelial Cells / Q000276:immunology* / Q000382:microbiology*; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D016209:Interleukin-8; C080866:cagA protein, Helicobacter pylori; D002784:Cholesterol