Dephosphorylated hypoxia-inducible factor 1alpha as a mediator of p53-dependent apoptosis during hypoxia

Oncogene. 2001 Sep 13;20(41):5779-88. doi: 10.1038/sj.onc.1204742.

Abstract

Under hypoxia, HIF-1alpha binds to aryl hydrocarbon receptor nuclear translocator (ARNT, also called HIF-1beta) to activate expression of genes important for cell survival. Alternatively, HIF-1alpha can bind to the tumor suppressor p53 and promote p53-dependent apoptosis. Here we show that the opposite functions of HIF-1alpha are distinguished by its phosphorylation status. Two distinguishable forms of HIF-1alpha, phosphorylated and dephosphorylated, were induced during hypoxia-induced apoptosis. The phosphorylated HIF-1alpha was the major form that bound to ARNT. Ectopically expressed ARNT was consistently able to enhance HIF-1alpha phosphorylation in a binding-dependent manner. In contrast, the dephosphorylated HIF-1alpha was the major form that bound to p53. Depletion of the dephosphorylated HIF-1alpha, by using the Hsp90 inhibitor geldanamycin A that had little effect on the phosphorylated HIF-1alpha expression, suppressed p53 induction and subsequent apoptosis. Depletion of dephosphorylated HIF-1alpha also prevented hypoxia-induced nuclear accumulation of HDM2, a negative regulator of p53. Our results indicate that the functions of HIF-1alpha varied with its phosphorylation status and that dephosphorylated HIF-1alpha mediated apoptosis by binding to and stabilizing p53.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Aryl Hydrocarbon Receptor Nuclear Translocator
  • Benzoquinones
  • Caspases / metabolism
  • Cell Hypoxia / physiology*
  • Cell Nucleus / metabolism
  • DNA-Binding Proteins / metabolism*
  • HSP90 Heat-Shock Proteins / pharmacology
  • Humans
  • Hypoxia-Inducible Factor 1
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Lactams, Macrocyclic
  • Nuclear Proteins / metabolism*
  • Phosphorylation
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-mdm2
  • Quinones / pharmacology
  • Receptors, Aryl Hydrocarbon*
  • Transcription Factors / metabolism*
  • Tumor Suppressor Protein p53 / drug effects
  • Tumor Suppressor Protein p53 / metabolism*

Substances

  • ARNT protein, human
  • Benzoquinones
  • DNA-Binding Proteins
  • HIF1A protein, human
  • HSP90 Heat-Shock Proteins
  • Hypoxia-Inducible Factor 1
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Lactams, Macrocyclic
  • Nuclear Proteins
  • Proto-Oncogene Proteins
  • Quinones
  • Receptors, Aryl Hydrocarbon
  • Transcription Factors
  • Tumor Suppressor Protein p53
  • Aryl Hydrocarbon Receptor Nuclear Translocator
  • MDM2 protein, human
  • Proto-Oncogene Proteins c-mdm2
  • Caspases
  • geldanamycin