Differential regulation of ERK1/2 and p38 MAP kinases in VacA-induced apoptosis of gastric epithelial cells.
Helicobacter pylori vacuolating cytotoxin A (VacA) has been considered as an apoptosis-inducing factor. Here, we investigated the mechanism of VacA-induced apoptosis in relation to the defense mechanism and MAP kinases pathway in gastric epithelial cells. AGS cells exposed to enriched VacA extracts affected the level of SOD-1 and villin. We further investigated the role of VacA in those inductions using a functional recombinant VacA (rVacA). Activation of p38 MAPK and Bax dimerization by rVacA were increased in a dose-dependent manner. rVacA-induced ERK1/2 MAPK activation was maximal at 30 min and 4 h and 1-4 microg/ml of rVacA. rVacA-induced SOD-1 expression was considerably diminished by inhibiting ERK1/2 MAPK and it was slightly increased by inhibiting p38 MAPK. rVacA increased or decreased villin expression depending on dose and exposure time and its expression was mainly appeared in the contractile actin ring of the dividing cells. Despite its cytoprotective effect, SB-203580, a p38 inhibitor, was unlikely to reduce VacA-induced Bax dimerization and rather inhibited villin and Bcl2 expression, indicating that p38 may also play a role in cell proliferation or differentiation for survival after VacA intoxication. Furthermore, p38 inhibitor accelerated rVacA-induced cell death after exposure of AGS cells to H(2)O(2) but ERK1/2 inhibitor protected cells from H(2)O(2) insult. These results suggest that SOD-1 and villin are expressed differentially upon VacA insult depending on dose and exposure time via ERK and p38 MAP kinases; decrease in SOD-1 and villin expression coupled with Bax dimerization leads to apoptosis of gastric epithelial cells.
Ki
Mi-Ran
MR
Department of Pathology, College of Veterinary Medicine, Kyungpook National University, Buk-ku, Daegu City, Republic of Korea.
Lee
Hye-Rim
HR
Goo
Moon-Jung
MJ
Hong
Il-Hwa
IH
Do
Sun-Hee
SH
Jeong
Da-Hee
DH
Yang
Hai-Jie
HJ
Yuan
Dong-Wei
DW
Park
Jin-Kyu
JK
Jeong
Kyu-Shik
KS
D017209:Apoptosis / Q000187:drug effects*; D001426:Bacterial Proteins / Q000494:pharmacology*; D015153:Blotting, Western; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D005753:Gastric Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016480:Helicobacter pylori / Q000378:metabolism; D006801:Humans; D007211:Indoles; D008840:Microfilament Proteins / Q000096:biosynthesis; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000096:biosynthesis; D000072105:Superoxide Dismutase-1; D014617:Vacuoles / Q000187:drug effects; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D001426:Bacterial Proteins; D005456:Fluorescent Dyes; D007211:Indoles; D008840:Microfilament Proteins; D011994:Recombinant Proteins; C000606290:SOD1 protein, human; C074689:VacA protein, Helicobacter pylori; D051028:bcl-2-Associated X Protein; C026615:villin; C007293:DAPI; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D016650:Fluorescein-5-isothiocyanate