title: Helicobacter pylori CagA protein can be tyrosine phosphorylated in gastric epithelial cells.
abstract: Attachment of Helicobacter pylori to gastric epithelial cells induces various cellular responses, including the tyrosine phosphorylation of an unknown 145-kD protein and interleukin 8 production. Here we show that this 145-kD protein is the cagA product of H. pylori, an immunodominant, cytotoxin-associated antigen. Epithelial cells infected with various H. pylori clinical isolates resulted in generation of tyrosine-phosphorylated proteins ranging from 130 to 145 kD in size that were also induced in vitro by mixing host cell lysate with bacterial lysate. When epithelial cells were infected with [(35)S]methionine-labeled H. pylori, a radioactive 145-kD protein was detected in the immunoprecipitates with antiphosphotyrosine antibody or anti-CagA (cytotoxin-associated gene A) antibody. Consistently, the 145-kD protein recognized by the anti-CagA and antiphosphotyrosine antibodies was induced in epithelial cells after infection of wild-type H. pylori but not the cagA::Km mutant. Furthermore, the amino acid sequence of the phosphorylated 145-kD protein induced by H. pylori infection was identical to the H. pylori CagA sequence. These results reveal that the tyrosine-phosphorylated 145-kD protein is H. pylori CagA protein, which may be delivered from attached bacteria into the host cytoplasm. The identification of the tyrosine-phosphorylated protein will thus provide further insights into understanding the precise roles of CagA protein in H. pylori pathogenesis.
authors.affiliation: Faculty of Nursing and Welfare, Fukui Prefectural University, Fukui 910-1195, Japan. asahi@fpu.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Asahi
authors.forename: T
authors.initials: T
authors.lastname: Azuma
authors.forename: S
authors.initials: S
authors.lastname: Ito
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
authors.forename: H
authors.initials: H
authors.lastname: Suto
authors.forename: Y
authors.initials: Y
authors.lastname: Nagai
authors.forename: M
authors.initials: M
authors.lastname: Tsubokawa
authors.forename: Y
authors.initials: Y
authors.lastname: Tohyama
authors.forename: S
authors.initials: S
authors.lastname: Maeda
authors.forename: M
authors.initials: M
authors.lastname: Omata
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: C
authors.initials: C
authors.lastname: Sasakawa
mesh_terms: D000595:Amino Acid Sequence; D000942:Antigens, Bacterial; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D066246:ErbB Receptors / Q000378:metabolism; D005753:Gastric Mucosa / Q000201:enzymology / Q000382:microbiology*; D016480:Helicobacter pylori / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010449:Peptide Mapping; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D016133:Polymerase Chain Reaction; D013276:Stomach Ulcer / Q000382:microbiology; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D010446:Peptide Fragments; C080866:cagA protein, Helicobacter pylori; D019000:Phosphotyrosine; D066246:ErbB Receptors; D019061:src-Family Kinases