title: Differential in vitro and cellular effects of iron chelators for hypoxia inducible factor hydroxylases.
abstract: Hypoxia inducible factor 1α (HIF-1α), an essential transcriptional factor, is negatively regulated by two different types of oxygen and Fe(2+) -dependent HIF hydroxylases, proline hydroxylase (PHD) and factor inhibiting HIF (FIH), under normoxia. Iron chelators have therefore been used for inducing HIF-1α expression by inhibiting the hydroxylases. In this study, the iron chelators displayed differential effects for PHD and FIH in cells depending on their iron specificity and membrane permeability rather than their in vitro potencies. The membrane permeability of the strict Fe(2+) -chelator potentially inhibited both hydroxylases, whereas the membrane impermeable one showed no inhibitory effect in cells. In contrast, the depletion of the extracellular Fe(3+) ion was mainly correlated to PHD inhibition, and the membrane permeable one elicited low efficacy for both enzymes in cells. The 3'-hydroxyl group of quercetin, a natural flavonoid, was critical for inhibition of intracellular hydroxylases. Since the 3'-methylation of quercetin is induced by catechol-O-methyl transferase, the enzyme may regulate the intracellular activity of quercetin. These data suggest that the multiple factors of iron-chelators may be responsible for regulating the intracellular activity HIF hydroxylases.
authors.affiliation: Bionanotechnology Research Center, KRIBB, Gwahak-ro, Yuseong-gu, Daejeon 305-806, Republic of Korea.
authors.forename: Eun A
authors.initials: EA
authors.lastname: Cho
authors.forename: Hyun Kyung
authors.initials: HK
authors.lastname: Song
authors.forename: Sang-Hyeup
authors.initials: SH
authors.lastname: Lee
authors.forename: Bong Hyun
authors.initials: BH
authors.lastname: Chung
authors.forename: Heon Man
authors.initials: HM
authors.lastname: Lim
authors.forename: Myung Kyu
authors.initials: MK
authors.lastname: Lee
mesh_terms: D000818:Animals; D058846:Antibodies, Monoclonal, Murine-Derived / Q000378:metabolism; D002463:Cell Membrane Permeability; D003001:Cloning, Molecular; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005290:Ferric Compounds / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D000860:Hypoxia / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D007501:Iron / Q000378:metabolism; D007502:Iron Chelating Agents / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism; D010618:Phenanthrolines / Q000494:pharmacology; D011393:Procollagen-Proline Dioxygenase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011794:Quercetin / Q000031:analogs & derivatives / Q000494:pharmacology; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D004791:Enzyme Inhibitors; D005290:Ferric Compounds; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007502:Iron Chelating Agents; D010618:Phenanthrolines; D012097:Repressor Proteins; C063423:rhamnetin; D011794:Quercetin; D007501:Iron; D006899:Mixed Function Oxygenases; C439790:HIF1AN protein, human; C490190:EGLN1 protein, human; D011393:Procollagen-Proline Dioxygenase; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; C025205:1,10-phenanthroline