Activation of the HIF prolyl hydroxylase by the iron chaperones PCBP1 and PCBP2

Cell Metab. 2011 Nov 2;14(5):647-57. doi: 10.1016/j.cmet.2011.08.015.

Abstract

Mammalian cells express dozens of iron-containing proteins, yet little is known about the mechanism of metal ligand incorporation. Human poly (rC) binding protein 1 (PCBP1) is an iron chaperone that binds iron and delivers it to ferritin, a cytosolic iron storage protein. We have identified the iron-dependent prolyl hydroxylases (PHDs) and asparaginyl hydroxylase (FIH1) that modify hypoxia-inducible factor α (HIFα) as targets of PCBP1. Depletion of PCBP1 or PCBP2 in cells led to loss of PHD activity, manifested by reduced prolyl hydroxylation of HIF1α, impaired degradation of HIF1α through the VHL/proteasome pathway, and accumulation of active HIF1 transcription factor. PHD activity was restored in vitro by addition of excess Fe(II), or purified Fe-PCBP1, and PCBP1 bound to PHD2 and FIH1 in vivo. These data indicated that PCBP1 was required for iron incorporation into PHD and suggest a broad role for PCBP1 and 2 in delivering iron to cytosolic nonheme iron enzymes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • DNA-Binding Proteins
  • Enzyme Activation
  • Ferritins / metabolism
  • Gene Expression
  • Genes, Reporter
  • Half-Life
  • Heterogeneous-Nuclear Ribonucleoproteins / genetics
  • Heterogeneous-Nuclear Ribonucleoproteins / metabolism*
  • Humans
  • Hydroxylation
  • Hypoxia / metabolism
  • Hypoxia-Inducible Factor 1, alpha Subunit / genetics
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism*
  • Ion Transport / physiology*
  • Iron / metabolism*
  • Luciferases / analysis
  • Molecular Chaperones / genetics
  • Molecular Chaperones / metabolism
  • Procollagen-Proline Dioxygenase / genetics
  • Procollagen-Proline Dioxygenase / metabolism*
  • Proteasome Endopeptidase Complex / metabolism
  • Protein Binding
  • RNA, Small Interfering
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • Signal Transduction / physiology*

Substances

  • DNA-Binding Proteins
  • HIF1A protein, human
  • Heterogeneous-Nuclear Ribonucleoproteins
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Molecular Chaperones
  • PCBP1 protein, human
  • PCBP2 protein, human
  • RNA, Small Interfering
  • RNA-Binding Proteins
  • Ferritins
  • Iron
  • Luciferases
  • Procollagen-Proline Dioxygenase
  • Proteasome Endopeptidase Complex