Copper-dependent activation of hypoxia-inducible factor (HIF)-1: implications for ceruloplasmin regulation

Blood. 2005 Jun 15;105(12):4613-9. doi: 10.1182/blood-2004-10-3980. Epub 2005 Mar 1.

Abstract

Cellular oxygen partial pressure is sensed by a family of prolyl-4-hydroxylase domain (PHD) enzymes that modify hypoxia-inducible factor (HIF)alpha subunits. Upon hydroxylation under normoxic conditions, HIFalpha is bound by the von Hippel-Lindau tumor suppressor protein and targeted for proteasomal destruction. Since PHD activity is dependent on oxygen and ferrous iron, HIF-1 mediates not only oxygen- but also iron-regulated transcriptional gene expression. Here we show that copper (CuCl(2)) stabilizes nuclear HIF-1alpha under normoxic conditions, resulting in hypoxia-response element (HRE)-dependent reporter gene expression. In in vitro hydroxylation assays CuCl(2) inhibited prolyl-4-hydroxylation independently of the iron concentration. Ceruloplasmin, the main copper transport protein in the plasma and a known HIF-1 target in vitro, was also induced in vivo in the liver of hypoxic mice. Both hypoxia and CuCl(2) increased ceruloplasmin (as well as vascular endothelial growth factor [VEGF] and glucose transporter 1 [Glut-1]) mRNA levels in hepatoma cells, which was due to transcriptional induction of the ceruloplasmin gene (CP) promoter. In conclusion, our data suggest that PHD/HIF/HRE-dependent gene regulation can serve as a sensory system not only for oxygen and iron but also for copper metabolism, regulating the oxygen-, iron- and copper-binding transport proteins hemoglobin, transferrin, and ceruloplasmin, respectively.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CHO Cells
  • Carcinoma, Hepatocellular / metabolism
  • Cell Line
  • Cell Nucleus / metabolism
  • Cell Proliferation
  • Ceruloplasmin / metabolism*
  • Coloring Agents / pharmacology
  • Copper / metabolism*
  • Cricetinae
  • DNA-Binding Proteins / metabolism*
  • Dose-Response Relationship, Drug
  • Gene Expression Regulation*
  • Genes, Reporter
  • Glucose Transporter Type 1
  • HeLa Cells
  • Humans
  • Hypoxia
  • Hypoxia-Inducible Factor 1
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Immunoblotting
  • Iron / metabolism*
  • Liver / metabolism
  • Luciferases / metabolism
  • Mice
  • Microscopy, Fluorescence
  • Monosaccharide Transport Proteins / metabolism
  • Nuclear Proteins / metabolism*
  • Oxygen / metabolism*
  • Procollagen-Proline Dioxygenase / metabolism
  • Promoter Regions, Genetic
  • RNA, Messenger / metabolism
  • Tetrazolium Salts / pharmacology
  • Thiazoles / pharmacology
  • Transcription Factors / metabolism*
  • Transcription, Genetic
  • Transfection
  • Vascular Endothelial Growth Factor A / metabolism

Substances

  • Coloring Agents
  • DNA-Binding Proteins
  • Glucose Transporter Type 1
  • HIF1A protein, human
  • Hif1a protein, mouse
  • Hypoxia-Inducible Factor 1
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Monosaccharide Transport Proteins
  • Nuclear Proteins
  • RNA, Messenger
  • SLC2A1 protein, human
  • Slc2a1 protein, mouse
  • Tetrazolium Salts
  • Thiazoles
  • Transcription Factors
  • Vascular Endothelial Growth Factor A
  • Copper
  • Iron
  • Luciferases
  • Procollagen-Proline Dioxygenase
  • Ceruloplasmin
  • thiazolyl blue
  • cupric chloride
  • Oxygen