A cis-acting region regulates oxidized lipid-mediated induction of the human heme oxygenase-1 gene in endothelial cells.
OBJECTIVE
Several proatherogenic agents including oxidized LDL and its major component, 13-hydroperoxyoctadecadienoic acid (13-HPODE), upregulate heme oxygenase-1 (HO-1). Our previous studies have demonstrated that 13-HPODE-mediated HO-1 induction occurs via transcriptional mechanisms. The purpose of this study was to evaluate the molecular regulation and identify the signaling pathways involved in 13-HPODE-mediated HO-1 induction in human aortic endothelial cells.


RESULTS
The half-life of HO-1 mRNA after stimulation with 13-HPODE was approximately 1.8 hours. Antioxidants such as N-acetylcysteine, iron chelation with deferoxamine mesylate, and protein kinase C inhibition with Gö6976 blocked HO-1 induction. Using promoter constructs up to 9.1 kb, no significant reporter activity was observed in response to 13-HPODE. A 13-HPODE-inducible DNase I hypersensitive site was identified that maps to a region approximately 10 to 11 kb from the transcription start site of the human HO-1 gene. Based on the DNase I analysis, a -11.6-kb human HO-1 promoter construct was generated and elicited a 2.5-fold increase in reporter activity, indicating that 13-HPODE-mediated human HO-1 induction requires, at least in part, sequences that reside between 9.1 and 11.6 kb of the human HO-1 promoter.


CONCLUSIONS
Elucidation of the molecular mechanisms which control HO-1 gene expression will allow us to develop therapeutic strategies to enhance the cytoprotective potential of HO-1 in atherosclerosis.
Hill-Kapturczak
Nathalie
N
Department of Medicine, Division of Nephrology, Hypertension and Transplantation, University of Florida, Gainesville, Fla 32610, USA.
Voakes
Christy
C
Garcia
Jairo
J
Visner
Gary
G
Nick
Harry S
HS
Agarwal
Anupam
A
D002478:Cells, Cultured; D003850:Deoxyribonuclease I / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism*; D004790:Enzyme Induction; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006207:Half-Life; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics* / Q000378:metabolism*; D051547:Heme Oxygenase-1; D006801:Humans; D008041:Linoleic Acids / Q000378:metabolism*; D050356:Lipid Metabolism; D008054:Lipid Peroxides / Q000378:metabolism*; D008565:Membrane Proteins; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010084:Oxidation-Reduction; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
D008041:Linoleic Acids; D008054:Lipid Peroxides; D008565:Membrane Proteins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C038649:13-hydroperoxy-9,11-octadecadienoic acid; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D020928:Mitogen-Activated Protein Kinases; D003850:Deoxyribonuclease I