Opposite expression of the antioxidant heme oxygenase-1 in primary cells and tumor cells: regulation by interaction of USF-2 and Fra-1.
Heme oxygenase-1 is the rate-limiting enzyme for the degradation of the prooxidant heme. Previously, we showed that an E-box within the HO-1 promoter is crucial for the regulation of HO-1 expression in primary hepatocytes. Further to investigate the importance of this E-box, we determined the regulatory capacity of the E-box-binding factor USF-2 in primary cells in comparison with transformed cell lines. We found that HO-1 expression was inhibited by USF-2 in primary cells, whereas it was induced in tumor cell lines. Mutation of either the E-box or the AP-1 site within the HO-1 promoter only partially affected the USF-dependent regulation. However, this regulation was dramatically reduced in tumor cells and completely abolished in primary cells transfected with an HO-1 promoter construct containing mutations in both the E-box and the AP-1 site, suggesting that AP-1 factors and USF-2 may act in a cooperative manner. Indeed, protein-protein interaction studies revealed that USF proteins interacted with Fra-1. Further, the USF-dependent HO-1 promoter activity was not detectable with an USF-2 mutant lacking residues of the USF-specific region (USR) or the transactivation domain encoded by exon 4. Together, these data suggest that USF-2 has opposite regulatory roles for HO-1 gene expression in primary cells and tumor cell lines.
Samoylenko
Anatoly
A
Department of Biochemistry, University of Kaiserslautern, Kaiserslautern, Germany.
Dimova
Elitsa Y
EY
Horbach
Tina
T
Teplyuk
Nadiya
N
Immenschuh
Stephan
S
Kietzmann
Thomas
T
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D024202:Electrophoretic Mobility Shift Assay; D006367:HeLa Cells; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism*; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D008297:Male; D008957:Models, Genetic; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D051720:Upstream Stimulatory Factors / Q000235:genetics / Q000378:metabolism*; D000099169:Fos-Related Antigen 1
D051547:Heme Oxygenase-1; D016760:Proto-Oncogene Proteins c-fos; D051720:Upstream Stimulatory Factors; D000099169:Fos-Related Antigen 1