Aldo-keto reductase 1 family B7 is the gene induced in response to oxidative stress in the livers of Long-Evans Cinnamon rats.
The Long-Evans Cinnamon (LEC) rat strain (Atp7b m/m), which accumulates copper in the liver due to mutations in the Atp7b gene, is a useful model for investigating the relationship between oxidative stress and hepatocarcinogenesis. To determine the effect of this mutation on oxidative stress marker genes, we performed oligonucleotide array analysis (Affymetrix), and compared the results in Atp7b m/m rats with those of a sibling line with the Atp7b w/w genotype. We focused our studies on the expression of the aldo-keto reductase 1 family B7 (AKR1B7)-like protein gene, since this gene codes for reductase enzymes involved in the detoxification of oxidizing compounds (e.g., aldehydes) and was differentially expressed in Atp7b m/m and Atp7b w/w rat liver. Akr1B7 mRNA expression was significantly increased in comparison with the expression of 4 other known oxidative stress responsive genes, haem-oxygenase-1 (HO-1), thioredoxin (Trx), aldehyde reductase (AKR1A1), and glucose-6-phosphate dehydrogenase (G6PDH). By searching binding motifs, five nuclear factor kappa B (NF-kappaB) binding sites were located in the 5'-upstream region of the akr1b7 gene. Transient co-transfection with both I-kappaBalpha and the Akr1b7 6 kb promoter (p6.0-AKR-Luc) inhibited luciferase activity of p6.0-AKR-Luc in HepG2 cells. Cuprous ion however did not affect the transcription activity induced by p6.0-AKR-luc. Gel-shift assay showed that the DNA binding activity of NF-kappaB increased in the livers of LEC rats, suggesting that the oxidative stress is mediated through NF-kappaB. The results indicate conclusively that in LEC rat liver, akr1b7 might be up-regulated by oxidative stress mediated through NF-kappaB, but not that mediated directly by copper.
Jia
Guang
G
Health Effects Research Team, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan.
Takahashi
Ryoya
R
Zhang
Zhiping
Z
Tsuji
Yoshiaki
Y
Sone
Hideko
H
D020121:5' Untranslated Regions / Q000378:metabolism; D000449:Aldehyde Reductase / Q000235:genetics*; D000818:Animals; D001665:Binding Sites; D003300:Copper / Q000494:pharmacology; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics; D051547:Heme Oxygenase-1 / Q000235:genetics; D020672:I-kappa B Proteins / Q000235:genetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D018384:Oxidative Stress / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D051381:Rats; D020332:Rats, Inbred LEC; D013879:Thioredoxins / Q000235:genetics; D015854:Up-Regulation
D020121:5' Untranslated Regions; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; C000606206:Nfkbia protein, rat; D012333:RNA, Messenger; D000072000:NF-KappaB Inhibitor alpha; D013879:Thioredoxins; D003300:Copper; C066498:Akr1b7 protein, mouse; D000449:Aldehyde Reductase; D005954:Glucosephosphate Dehydrogenase; D051547:Heme Oxygenase-1