2-Oxoglutarate-dependent oxygenases control hepcidin gene expression.
OBJECTIVE
Hepcidin is a liver-produced hormone that regulates systemic iron homeostasis. Hepcidin expression is stimulated upon iron overload or inflammation while iron deficiency, anemia and tissue hypoxia are negative regulators. We investigated the involvement of 2-oxoglutarate-dependent oxygenases, HIF-1 and other transcription factors in the hypoxic suppression of hepcidin.


METHODS
Northern blotting analysis and real time PCR were used to determine hepcidin mRNA levels in hepatoma cells and hepcidin promoter activity was measured using Huh7 cells transfected with suitable reporter constructs under various conditions.


RESULTS
Treatment of human cultured hepatoma cells with hypoxia or known inhibitors of 2-oxoglutarate-dependent oxygenases, such as the iron chelator desferrioxamine, cobalt or the 2-oxoglutarate analogue dimethyl-oxalylglycine significantly reduced hepcidin mRNA levels and down-regulated its gene promoter activity. This effect was not dependent on the HREs or other known putative response elements in the hepcidin promoter and was observed even under interleukin-6 treatment.


CONCLUSIONS
2-Oxoglutarate-dependent oxygenases are important to maintain high hepcidin mRNA expression in a HIF-1-independent manner. We suggest that modulation of oxygenase activity may be of therapeutic value in iron-related disorders.
Braliou
Georgia G
GG
Laboratory of Biochemistry, Department of Medicine, University of Thessaly, 22 Papakyriazi Street, Larissa, Greece.
Verga Falzacappa
Maria Vittoria
MV
Chachami
Georgia
G
Casanovas
Guillem
G
Muckenthaler
Martina U
MU
Simos
George
G
D023181:Antimicrobial Cationic Peptides / Q000235:genetics*; D045744:Cell Line, Tumor; D005786:Gene Expression Regulation; D064451:Hepcidins; D006801:Humans; D051793:Hypoxia-Inducible Factor 1 / Q000502:physiology; D015850:Interleukin-6 / Q000096:biosynthesis; D007656:Ketoglutaric Acids / Q000378:metabolism*; D010105:Oxygenases / Q000037:antagonists & inhibitors / Q000502:physiology*; D011401:Promoter Regions, Genetic; D017382:Reactive Oxygen Species; D050791:STAT Transcription Factors / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism
D023181:Antimicrobial Cationic Peptides; C578702:HAMP protein, human; D064451:Hepcidins; D051793:Hypoxia-Inducible Factor 1; D015850:Interleukin-6; D007656:Ketoglutaric Acids; D017382:Reactive Oxygen Species; D050791:STAT Transcription Factors; D018808:Transcription Factor AP-1; D010105:Oxygenases