Oxygen sensing by the prolyl-4-hydroxylase PHD2 within the nuclear compartment and the influence of compartmentalisation on HIF-1 signalling

J Cell Sci. 2012 Nov 1;125(Pt 21):5168-76. doi: 10.1242/jcs.109041. Epub 2012 Sep 3.


Hypoxia-inducible factors (HIFs) regulate more than 200 genes involved in cellular adaptation to reduced oxygen availability. HIFs are heterodimeric transcription factors that consist of one of three HIF-α subunits and a HIF-β subunit. Under normoxic conditions the HIF-α subunit is hydroxylated by members of a family of prolyl-4-hydroxylase domain (PHD) proteins, PHD1, PHD2 and PHD3, resulting in recognition by von-Hippel-Lindau protein, ubiquitylation and proteasomal degradation. It has been suggested that PHD2 is the key regulator of HIF-1α stability in vivo. Previous studies on the intracellular distribution of PHD2 have provided evidence for a predominant cytoplasmic localisation but also nuclear activity of PHD2. Here, we investigated functional nuclear transport signals in PHD2 and identified amino acids 196-205 as having a crucial role in nuclear import, whereas amino acids 6-20 are important for nuclear export. Fluorescence resonance energy transfer (FRET) showed that an interaction between PHD2 and HIF-1α occurs in both the nuclear and cytoplasmic compartments. However, a PHD2 mutant that is restricted to the cytoplasm does not interact with HIF-1α and shows less prolyl hydroxylase activity for its target HIF-1α than wild-type PHD2 located in the nucleus. Here, we present a new model by which PHD2-mediated hydroxylation of HIF-1α predominantly occurs in the cell nucleus and is dependent on very dynamic subcellular trafficking of PHD2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus
  • Cell Line, Tumor
  • Cell Nucleus / enzymology*
  • Gene Expression
  • Gene Expression Regulation
  • Genes, Reporter
  • Green Fluorescent Proteins / metabolism
  • HEK293 Cells
  • Humans
  • Hydroxylation
  • Hypoxia-Inducible Factor 1, alpha Subunit / genetics
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism*
  • Hypoxia-Inducible Factor-Proline Dioxygenases
  • Luciferases, Firefly / biosynthesis
  • Luciferases, Firefly / genetics
  • Microscopy, Fluorescence
  • Nuclear Localization Signals
  • Oxygen / metabolism*
  • Procollagen-Proline Dioxygenase / chemistry
  • Procollagen-Proline Dioxygenase / genetics
  • Procollagen-Proline Dioxygenase / metabolism*
  • Protein Processing, Post-Translational
  • Recombinant Fusion Proteins / metabolism
  • Sequence Deletion
  • Signal Transduction*
  • Transcription, Genetic


  • HIF1A protein, human
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Nuclear Localization Signals
  • Recombinant Fusion Proteins
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins
  • Luciferases, Firefly
  • EGLN1 protein, human
  • Procollagen-Proline Dioxygenase
  • Hypoxia-Inducible Factor-Proline Dioxygenases
  • Oxygen