γ-Glutamyltranspeptidase of Helicobacter pylori induces mitochondria-mediated apoptosis in AGS cells

• DOI: 10.1016/j.bbrc.2007.02.021
• Publication Date: 2007-02-13T12:07:38Z
• Authors: Kyung-Mi Kim; Seung-Gyu Lee; Min-Gyu Park; Jea-Young Song; Hyung-Lyun Kang; Woo-Kon Lee; Myung-Je Cho; Kwang-Ho Rhee; Hee-Shang Youn; Seung-Chul Baik
• Keywords: 0303 health sciences; Microscopy, Confocal; Base Sequence; Helicobacter pylori; Apoptosis; gamma-Glutamyltransferase; Adenocarcinoma; Recombinant Proteins; Mitochondria; 3. Good health; 03 medical and health sciences; Microscopy, Fluorescence; Stomach Neoplasms; Tumor Cells, Cultured; Humans; Electrophoresis, Polyacrylamide Gel; DNA Primers

Gamma-glutamyltranspeptidase (GGT) is a novel protein involved in the induction of Helicobacter pylori-mediated apoptosis; however, the signal pathway involved in GGT-induced apoptosis remains unclear. Using DNA recombination techniques, ggt was cloned into pET117b and transformed into Escherichia coli. Recombinant GGT was purified using nickel-affinity resin and was digested by thrombin. Recombinant GGT induced apoptosis in AGS cells in a time-dependent manner, which was confirmed by TUNEL staining, the MTT assay and immunoblot analysis for caspases-9, -3, Bax, Bcl-2, Bcl-xL and cytochrome c release. Activation of caspase-3 and -9 following exposure to GGT increased in a time-dependent manner and upregulation of proapoptotic Bax and a downregulation of antiapoptotic Bcl-2 and Bcl-xL was detected. Apoptotic signals also trigger changes in mitochondria, which lead to a release of cytochrome c into the cytosolic space. The GGT-deficient mutant was not as able to induce apoptosis as the wild-type strain. These results indicate that GGT of H. pylori induces apoptosis via a mitochondria-mediated pathway.