Interleukin-8 induction by Helicobacter pylori in gastric epithelial cells is dependent on apurinic/apyrimidinic endonuclease-1/redox factor-1.
Helicobacter pylori infection causes inflammation and increases the expression of IL-8 in human gastric epithelial cells. H. pylori activates NF-kappaB and AP-1, essential transcriptional factors in H. pylori-induced IL-8 gene transcription. Although colonization creates a local oxidative stress, the molecular basis for the transition from infection to the expression of redox-sensitive cytokine genes is unknown. We recently reported that the expression of apurinic/apyrimidinic endonuclease-1/redox factor-1 (APE-1/Ref-1), which repairs oxidative DNA damage and reductively activates transcription factors including AP-1 and NF-kappaB, is increased in human gastric epithelia during H. pylori infection. In this study, we examine whether APE-1/Ref-1 functions in the modulation of IL-8 gene expression in H. pylori-infected human gastric epithelial cells. Small interfering RNA-mediated silencing of APE-1/Ref-1 inhibited basal and H. pylori-induced AP-1 and NF-kappaB DNA-binding activity without affecting the nuclear translocation of these transcription factors and also reduced H. pylori-induced IL-8 mRNA and protein. In contrast, overexpression of APE-1/Ref-1 enhanced basal and H. pylori-induced IL-8 gene transcription, and the relative involvement of AP-1 in inducible IL-8 promoter activity was greater in APE-1/Ref-1 overexpressing cells than in cells with basal levels of APE-1/Ref-1. APE-1/Ref-1 inhibition also reduced other H. pylori-induced chemokine expression. By implicating APE-1/Ref-1 as an important regulator of gastric epithelial responses to H. pylori infection, these data elucidate a novel mechanism controlling transcription and gene expression in bacterial pathogenesis.
O'Hara
Ann M
AM
Department of Internal Medicine, University of Virginia, Charlottesville, VA 22908, USA.
Bhattacharyya
Asima
A
Mifflin
Randy C
RC
Smith
Michael F
MF
Ryan
Kieran A
KA
Scott
Kevin G-E
KG
Naganuma
Makoto
M
Casola
Antonella
A
Izumi
Tadahide
T
Mitra
Sankar
S
Ernst
Peter B
PB
Crowe
Sheila E
SE
D002460:Cell Line; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D005753:Gastric Mucosa / Q000276:immunology* / Q000382:microbiology; D015870:Gene Expression; D020868:Gene Silencing; D016481:Helicobacter Infections / Q000276:immunology*; D016480:Helicobacter pylori / Q000276:immunology; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D007834:Lasers; D042282:Microdissection; D016328:NF-kappa B / Q000276:immunology / Q000378:metabolism; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018808:Transcription Factor AP-1 / Q000276:immunology / Q000378:metabolism; D014158:Transcription, Genetic
D016209:Interleukin-8; D016328:NF-kappa B; D034741:RNA, Small Interfering; D018808:Transcription Factor AP-1; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase