| Summary: | 碩士 === 國立臺灣大學 === 生物化學暨分子生物學研究所 === 96 === Helicobacter pylori (H. pylori) which can cause chronic inflammation is now emerging as a risk factor in the development of chronic gastritis, duodenal ulcer, gastric ulcer, and gastric cancer (1-2%). Although many virulence factors of H. pylori have been reported, but the pathogenic mechanism of H. pylori still remains unclear. In the previous study, we have found a novel GC-associated virulence factor which is GroES of H. pylori and this protein may contribute to gastric carcinogenesis via induction of inflammation and promotion of cell proliferation. GroES, a heat shock protein family is well known as a co-chaperone with GroEL.
In the previous study of Escherichia coli GroES, it showed significant activity only on the expression and release of IL-6 in keratinocytes and E-selectin in monocytes and endothelial cells. So It sound like that there is no immunogencity in Escherichia coli GroES-treat cells. H. pylori GroES contains 118 amino acids. After comparing the amino acid sequences, the difference among GroES of different species was that there are extra 28-amino-acid in the carboxyl terminus of Helicobacter pylori GroES. This region was not present in any of the other bacterial GroES homologues characterized.
We were interested in the contribution of the 28-amino-acid carboxyl terminus of H. pylori GroES in the effect of inflammation. We deleted the 28-amino-acid carboxyl terminus of H. pylori GroES and purified the protein that contains 1-90 amino acids of H. pylori GroES〈△rGroES(1-90)〉. We investigated the IL-8 expression in △rGroES(1-90)-treated PBMC (peripheral blood mononuclear cell) and gastric epithelial cell (KATO-Ⅲ). By comparing with wild type H. pylori and E. coli GroES, we found that deletion of C-terminal amino acid (91-118) of H. pylori GroES reduce IL-8 expression in both cells. It can be observed that △rGroES(1-90) doesn’t bind to surface of KATO-Ⅲ cell but H. Pylori rGroES(1-118) does.
The synthesized peptide of H. pylori C-terminal amino acid (91-118) can induce IL-8 expression in PBMC. This peptide may contribute to the activity of H. pylori GroES whereas △rGroES(1-90) has no effect on IL-8 expression. Therefore, GroES seems to be involved in the inflammatory response of H. Pylori infection through its carboxyl terminus of 28-amino-acid.
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