title: Helicobacter pylori CagA targets PAR1/MARK kinase to disrupt epithelial cell polarity.
abstract: Helicobacter pylori cagA-positive strains are associated with gastritis, ulcerations and gastric adenocarcinoma. CagA is delivered into gastric epithelial cells and, on tyrosine phosphorylation, specifically binds and activates the SHP2 oncoprotein, thereby inducing the formation of an elongated cell shape known as the 'hummingbird' phenotype. In polarized epithelial cells, CagA also disrupts the tight junction and causes loss of apical-basolateral polarity. We show here that H. pylori CagA specifically interacts with PAR1/MARK kinase, which has an essential role in epithelial cell polarity. Association of CagA inhibits PAR1 kinase activity and prevents atypical protein kinase C (aPKC)-mediated PAR1 phosphorylation, which dissociates PAR1 from the membrane, collectively causing junctional and polarity defects. Because of the multimeric nature of PAR1 (ref. 14), PAR1 also promotes CagA multimerization, which stabilizes the CagA-SHP2 interaction. Furthermore, induction of the hummingbird phenotype by CagA-activated SHP2 requires simultaneous inhibition of PAR1 kinase activity by CagA. Thus, the CagA-PAR1 interaction not only elicits the junctional and polarity defects but also promotes the morphogenetic activity of CagA. Our findings revealed that PAR1 is a key target of H. pylori CagA in the disorganization of gastric epithelial architecture underlying mucosal damage, inflammation and carcinogenesis.
authors.affiliation: Division of Molecular Oncology, Institute for Genetic Medicine, Graduate School of Science, Hokkaido University, Sapporo 060-0815, Japan.
authors.forename: Iraj
authors.initials: I
authors.lastname: Saadat
authors.forename: Hideaki
authors.initials: H
authors.lastname: Higashi
authors.forename: Chikashi
authors.initials: C
authors.lastname: Obuse
authors.forename: Mayumi
authors.initials: M
authors.lastname: Umeda
authors.forename: Naoko
authors.initials: N
authors.lastname: Murata-Kamiya
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Saito
authors.forename: Huaisheng
authors.initials: H
authors.lastname: Lu
authors.forename: Naomi
authors.initials: N
authors.lastname: Ohnishi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Azuma
authors.forename: Atsushi
authors.initials: A
authors.lastname: Suzuki
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ohno
authors.forename: Masanori
authors.initials: M
authors.lastname: Hatakeyama
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D016764:Cell Polarity; D004847:Epithelial Cells / Q000166:cytology* / Q000201:enzymology* / Q000473:pathology; D016480:Helicobacter pylori; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D047908:Intracellular Signaling Peptides and Proteins; C080866:cagA protein, Helicobacter pylori; C105547:MARK1 protein, human; D017346:Protein Serine-Threonine Kinases; C516724:PTPN11 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases