Staphylococcus aureus sepsis and mitochondrial accrual of the 8-oxoguanine DNA glycosylase DNA repair enzyme in mice.
BACKGROUND
Damage to mitochondrial DNA (mtDNA) by the production of reactive oxygen species during inflammatory states, such as sepsis, is repaired by poorly understood mechanisms.


OBJECTIVE
To test the hypothesis that the DNA repair enzyme, 8-oxoguanine DNA glycosylase (OGG1), contributes to mtDNA repair in sepsis.


METHODS
Using a well-characterized mouse model of Staphylococcus aureus sepsis, we analyzed molecular markers for mitochondrial biogenesis and OGG1 translocation into liver mitochondria as well as OGG1 mRNA expression at 0, 24, 48, and 72 hours after infection. The effects of OGG1 RNA silencing on mtDNA content were determined in control, tumor necrosis factor-α, and peptidoglycan-exposed rat hepatoma cells. Based on in situ analysis of the OGG1 promoter region, chromatin immunoprecipitation assays were performed for nuclear respiratory factor (NRF)-1 and NRF-2α GA-binding protein (GABP) binding to the promoter of OGG1.


RESULTS
Mice infected with 10(7) cfu S. aureus intraperitoneally demonstrated hepatic oxidative mtDNA damage and significantly lower hepatic mtDNA content as well as increased mitochondrial OGG1 protein and enzyme activity compared with control mice. The infection also caused increases in hepatic OGG1 transcript levels and NRF-1 and NRF-2α transcript and protein levels. A bioinformatics analysis of the Ogg1 gene locus identified several promoter sites containing NRF-1 and NRF-2α DNA binding motifs, and chromatin immunoprecipitation assays confirmed in situ binding of both transcription factors to the Ogg1 promoter within 24 hours of infection.


CONCLUSIONS
These studies identify OGG1 as an early mitochondrial response protein during sepsis under regulation by the NRF-1 and NRF-2α transcription factors that regulate mitochondrial biogenesis.
Bartz
Raquel R
RR
Department of Anesthesiology, DUMC Box 3094, Durham, NC 27710, USA. bartz001@mc.duke.edu
Suliman
Hagir B
HB
Fu
Ping
P
Welty-Wolf
Karen
K
Carraway
Martha Sue
MS
MacGarvey
Nancy Chou
NC
Withers
Crystal M
CM
Sweeney
Timothy E
TE
Piantadosi
Claude A
CA
D000818:Animals; D015153:Blotting, Western; D045647:DNA Glycosylases / Q000378:metabolism*; D004260:DNA Repair; D004272:DNA, Mitochondrial / Q000378:metabolism*; D004195:Disease Models, Animal; D051268:GA-Binding Protein Transcription Factor / Q000378:metabolism; D047468:Immunoprecipitation / Q000379:methods; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008930:Mitochondria, Liver / Q000201:enzymology*; D051266:Nuclear Respiratory Factor 1 / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018805:Sepsis / Q000201:enzymology* / Q000382:microbiology; D013211:Staphylococcus aureus
D004272:DNA, Mitochondrial; D051268:GA-Binding Protein Transcription Factor; C495656:Gabpa protein, mouse; C495634:Nrf1 protein, mouse; D051266:Nuclear Respiratory Factor 1; D017382:Reactive Oxygen Species; D045647:DNA Glycosylases; C485990:Ogg1 protein, mouse