title: Helicobacter pylori CagA targets gastric tumor suppressor RUNX3 for proteasome-mediated degradation.
abstract: Chronic infection with cagA-positive Helicobacter pylori is the strongest risk factor for the development of gastric adenocarcinoma. The cagA gene product CagA is injected into gastric epithelial cells and disturbs cellular functions by physically interacting with and deregulating a variety of cellular signaling molecules. RUNX3 is a tumor suppressor in many tissues, and it is frequently inactivated in gastric cancer. In this study, we show that H. pylori infection inactivates the gastric tumor suppressor RUNX3 in a CagA-dependent manner. CagA directly associates with RUNX3 through a specific recognition of the PY motif of RUNX3 by a WW domain of CagA. Deletion of the WW domains of CagA or mutation of the PY motif in RUNX3 abolishes the ability of CagA to induce the ubiquitination and degradation of RUNX3, thereby extinguishing its ability to inhibit the transcriptional activation of RUNX3. Our studies identify RUNX3 as a novel cellular target of H. pylori CagA and also reveal a mechanism by which CagA functions as an oncoprotein by blocking the activity of gastric tumor suppressor RUNX3.
authors.affiliation: Department of Biochemistry, College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Y H
authors.initials: YH
authors.lastname: Tsang
authors.forename: A
authors.initials: A
authors.lastname: Lamb
authors.forename: J
authors.initials: J
authors.lastname: Romero-Gallo
authors.forename: B
authors.initials: B
authors.lastname: Huang
authors.forename: K
authors.initials: K
authors.lastname: Ito
authors.forename: R M
authors.initials: RM
authors.lastname: Peek
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
authors.forename: L F
authors.initials: LF
authors.lastname: Chen
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D019556:COS Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D050677:Core Binding Factor Alpha 3 Subunit / Q000235:genetics / Q000378:metabolism*; D005753:Gastric Mucosa / Q000378:metabolism / Q000473:pathology / Q000821:virology; D016481:Helicobacter Infections / Q000378:metabolism / Q000821:virology; D016480:Helicobacter pylori / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D054884:Host-Pathogen Interactions; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D051379:Mice; D009154:Mutation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011485:Protein Binding; D013274:Stomach Neoplasms / Q000378:metabolism / Q000473:pathology / Q000821:virology; D014162:Transfection
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D050677:Core Binding Factor Alpha 3 Subunit; C493729:Runx3 protein, human; C080866:cagA protein, Helicobacter pylori; D046988:Proteasome Endopeptidase Complex