Helicobacter pylori and H2O2 increase AP endonuclease-1/redox factor-1 expression in human gastric epithelial cells.
OBJECTIVE
Helicobacter pylori infection causes inflammation, accumulation of reactive oxygen species, and oxidative DNA damage in the gastric mucosa. Apurinic/apyrimidinic endonuclease-1 (APE-1)/redox factor-1 (Ref-1) repairs damaged DNA and reductively activates transcription factors, including activator protein-1. Considering that H. pylori generate reactive oxygen species and that reactive oxygen species modulate APE-1/Ref-1 in other cell types, we examined the effect of H. pylori, oxidative stress, and antioxidants on APE-1/Ref-1 expression in human gastric epithelial cells.


METHODS
Human gastric epithelial cell lines or cells isolated from mucosal biopsy samples were stimulated with H. pylori, Campylobacter jejuni, and/or H 2 O 2 in the presence or absence of antioxidants. APE-1/Ref-1 expression was assayed by Western blot or reverse-transcription polymerase chain reaction, and its cellular distribution was determined by using indirect conventional and confocal immunofluorescence. New protein synthesis was detected by [S 35 ]methionine labeling. APE-1/Ref-1 function was assessed by using a luciferase-linked reporter construct containing 3 activator protein 1 binding sites.


RESULTS
APE-1/Ref-1 protein and messenger RNA were detected in resting gastric epithelial cells. APE-1/Ref-1 protein expression was increased after stimulation with H 2 O 2 or live cag pathogenicity island-bearing H. pylori, but not cag pathogenicity island-negative H. pylori or C. jejuni. H. pylori - or reactive oxygen species-mediated increases in APE-1/Ref-1 expression involved de novo protein synthesis that was inhibited by antioxidants. H. pylori or H 2 O 2 also induced nuclear accumulation of APE-1/Ref-1, and overexpression of APE-1/Ref-1 increased activator protein 1 binding activity.


CONCLUSIONS
The data show that H. pylori or reactive oxygen species enhance APE-1/Ref-1 protein synthesis and nuclear accumulation in human gastric epithelial cells and implicate APE-1/Ref-1 in the modulation of the pathogenesis of H. pylori infection.
Ding
Song-Ze
SZ
Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, USA.
O'Hara
Ann M
AM
Denning
Tim L
TL
Dirden-Kramer
Bernadette
B
Mifflin
Randy C
RC
Reyes
Victor E
VE
Ryan
Kieran A
KA
Elliott
Susan N
SN
Izumi
Tadahide
T
Boldogh
Istvan
I
Mitra
Sankar
S
Ernst
Peter B
PB
Crowe
Sheila E
SE
D000942:Antigens, Bacterial / Q000378:metabolism; D000975:Antioxidants / Q000494:pharmacology; D001426:Bacterial Proteins / Q000378:metabolism; D002169:Campylobacter Infections / Q000378:metabolism; D016123:Campylobacter jejuni / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D004260:DNA Repair / Q000502:physiology; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000096:biosynthesis*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology; D016481:Helicobacter Infections / Q000378:metabolism*; D016480:Helicobacter pylori / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D018384:Oxidative Stress / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism
D000942:Antigens, Bacterial; D000975:Antioxidants; D001426:Bacterial Proteins; D017382:Reactive Oxygen Species; C080866:cagA protein, Helicobacter pylori; D006861:Hydrogen Peroxide; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase