FOXO4 induces human plasminogen activator inhibitor-1 gene expression via an indirect mechanism by modulating HIF-1alpha and CREB levels.
The plasminogen activator inhibitor-1 (PAI-1) expression can be enhanced by hypoxia and various stimuli associated with oxidative stress. Among the FOXO transcription factors, FOXO4 appears to be crucial in the response against oxidative stress. Therefore, it was the aim of this study to investigate the role of peroxide-induced oxidative stress and FOXO4 on PAI-1 expression under normoxia and hypoxia. Treatment of cells with hydrogen peroxide increased PAI-1 mRNA, protein, and promoter activity, and knocking down FOXO4 abolished the peroxide-dependent PAI-1 induction. PAI-1 promoter reporter gene assays revealed that the peroxide and FOXO4-dependent induction was mediated through the HIF-1 and CREB-binding HRE within the PAI-1 promoter. Western blot analyses then indicated that peroxide and FOXO4 downregulated HIF-1alpha levels, whereas CREB levels were increased. Chromatin immunoprecipitations showed that FOXO4 did not bind the PAI-1 promoter, whereas CREB binding was enhanced on FOXO4 overexpression. In addition, knockdown of CREB abolished the FOXO4-mediated PAI-1 induction. Together, these findings provide the first evidence that oxidative stress and FOXO4 induce PAI-1 expression through an indirect mechanism involving modulation of HIF-1alpha and CREB protein levels and that enhanced CREB binding to the PAI-1 promoter is critical for the PAI-1 induction under oxidative stress.
Department of Biochemistry, University of Kaiserslautern , Kaiserslautern, Germany. dimova@chemie.uni-kl.de
Elitsa Y
EY
Dimova
Anatoly
A
Samoylenko
Thomas
T
Kietzmann
D001665:Binding Sites; D001692:Biological Transport / Q000235:genetics / Q000502:physiology; D015152:Blotting, Northern; D015153:Blotting, Western; D050882:CREB-Binding Protein / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D051858:Forkhead Transcription Factors; D056945:Hep G2 Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000235:genetics / Q000502:physiology; D034741:RNA, Small Interfering; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D018797:Cell Cycle Proteins; C108803:FOXO4 protein, human; D051858:Forkhead Transcription Factors; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D017395:Plasminogen Activator Inhibitor 1; D034741:RNA, Small Interfering; C051321:SERPINE1 protein, human; D014157:Transcription Factors; D006861:Hydrogen Peroxide; D050882:CREB-Binding Protein; C494363:CREBBP protein, human