2002 Fiscal Year Final Research Report Summary
The Tyrosine-phosphorylation Mechanism of CagA Protein Secreted from Helicobacter Pylori and The Physiological Significance
| Project/Area Number |
13670541
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Gastroenterology
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| Research Institution | Fukui Prefectural University |
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Principal Investigator |
ASAHI Momoyo Fukui Prefectural University, Center for Arts and Science, Associate Professor, 看護福祉学部, 助教授 (60100624)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Helicobacter pylori / CagA protein / Tyrosine-phosphorylation / Itam-like Sequences / Gastric Cancer / Gastric Ulcer / Lipid Rafts / Vaca |
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| Research Abstract |
Helicobacter pylori CagA is injected into the host cell and tyrosine-phosphorylated. We examined tyrosine-phosphorylation sites of CagA, as well as the function of CagA proteins in vivo and in vitro. After proteolytic digestion of CagA with lysyl endopeptidase, CagA tyrosine-phosphorylation sites were determined using quadropolar time-of flight mass spectrometry analysis. Specific anti-pY CagA polyclonal and anti-CagA monoclonal antibodies were used to examine gastric mucosal biopsy specimens from H. pylori infected patients. Mass spectrometry identified five crucial tyrosine-phosphorylation sites of CagA at Tyr893. Tyr912, Tyr965, Tyr999, and Tyr1033 within the five repeated EPIYA sequences of H.pylori (NCTC11637)-infected AGS cells. CagA protein also had an immunoreceptor tyrosine-based activation motif (ITAM)-like amino acid sequences in the 3' region of the cagA, EPIYATIx_<27>EIYATI, which closely resembled the ITAM. CagA proteins, (i) were localized to the 1% TritonX-100 resistant membrane fraction (lipid rafts), (ii) formed a cluster of phosphorylated CagA protein complexes, (iii) associated with tyrosine-phosphorrylated GIT1/Cat1 (G protein-coupled receptor kinase-interactor 1/ Cool-associated, tyrosine-phosphorylated 1), substrate molecules of receptor type protein-tyrosine phosphatase, (RPTPζ/β), which is the receptor of VacA and (iv) were involved in a delay and negative regulation of VacA-induced signal. Immunohistochemical staining of gastric mucosal biopsy specimens provided strong evidence that tyrosine-phosphorylated CagA is found together with CagA at the luminal surface of gastric foveola in vivo. These findings suggest an important role for CagA containing ITAM-like sequences in the pathogenesis of H.pylori-related disease.
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[Publications] Asahi M., Tanaka Y., Izumi T., Ito Y., Naiki H., Kersulyte D., Tsujikawa K., Saito M., Sada K., Yanagi S., Fujikawa A., Noda M., Itokawa Y.: "Helicobacter pylori CagA containing ITAM-like sequences localized to lipid rafts negatively regulates VacA-induced signaling in vivo"Helicobacter. 8(1). 1-14 (2003)
Description
「研究成果報告書概要(和文)」より
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[Publications] Asahi M., Tanaka Y., Izumi T., Ito Y., Naiki H., Kersulyte D., Tsujikawa K., Saito M., Sada K., Yanagi S., Fujikawa A., Noda M., and Itokawa Y.: "Helicobacter pylori CagA containing ITAM-like sequences localized to lipid rafts negatively regulates VacA-induced signaling in vivo"Helicobacter. 8(1). 1-14 (2003)
Description
「研究成果報告書概要(欧文)」より
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