Hinokitiol activates the hypoxia-inducible factor (HIF) pathway through inhibition of HIF hydroxylases.
Hypoxia-inducible factor (HIF)-1 has been established as a master regulator of vascular responses to hypoxia and ischemia by driving transcriptional activation of angiogenic factors. Oxygen- and 2-oxoglutarate (2-OG)-dependent, iron(II) containing HIF-specific prolyl-4-hydroxylases (PHDs) and factor inhibiting HIF-1alpha (FIH-1) catalyze the hydroxylation of the specific proline and asparagine residues of HIF-1alpha, thereby controlling the level of HIF-1alpha and ultimately the HIF response. Here, we unveil a new action of hinokitiol, an iron chelator found in natural plants, on stabilization of HIF-1alpha in cell cultures in a dose-dependent manner. In vitro PHD2 and FIH activity assays based on fluorescence polarization reveal that such HIF-1alpha stabilization is likely medicated by inhibitory effects of hinokitiol on prolyl and asparaginyl hydroxylation of HIF-1alpha. In addition, the inhibition of PHD2 by hinokitiol is reversed by the addition of 2-OG and iron(II), suggesting that the underlying inhibitory mechanism involves displacement of 2-OG and a chelate formation with iron(II) at the enzyme active site by hinokitiol. Furthermore, hinokitiol treated cells show increased transcription of vascular endothelial growth factor, providing the therapeutic potential in the treatment of ischemic diseases.
Lee
Myong Jin
MJ
Life Sciences Research Division, Korea Institute of Science and Technology, PO Box 131, Cheongryang, Seoul 130-650, Republic of Korea.
Kim
Jeong Won
JW
Yang
Eun Gyeong
EG
D045744:Cell Line, Tumor; D006801:Humans; D006900:Hydroxylation / Q000187:drug effects; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000819:agonists*; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D007502:Iron Chelating Agents / Q000494:pharmacology*; D006899:Mixed Function Oxygenases; D039821:Monoterpenes / Q000494:pharmacology*; D011393:Procollagen-Proline Dioxygenase / Q000037:antagonists & inhibitors*; D012097:Repressor Proteins / Q000037:antagonists & inhibitors; D014158:Transcription, Genetic / Q000187:drug effects; D014334:Tropolone / Q000031:analogs & derivatives* / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics
D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007502:Iron Chelating Agents; D039821:Monoterpenes; D012097:Repressor Proteins; D042461:Vascular Endothelial Growth Factor A; D014334:Tropolone; D006899:Mixed Function Oxygenases; C439790:HIF1AN protein, human; C490190:EGLN1 protein, human; D011393:Procollagen-Proline Dioxygenase; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; C009479:beta-thujaplicin