A dominant-negative isoform lacking exons 11 and 12 of the human hypoxia-inducible factor-1alpha gene

Biochem J. 2002 Feb 15;362(Pt 1):71-9. doi: 10.1042/0264-6021:3620071.


Hypoxia-inducible factor-1alpha (HIF-1alpha), a member of the transcription family characterized by a basic helix-loop-helix (bHLH) domain and a PAS domain, regulates the transcription of hypoxia-inducible genes involved in erythropoiesis, vascular remodelling and glucose/energy metabolism. It contains bHLH/PAS domains in the N-terminal half, and a nuclear localization signal (NLS) and two transactivation domains (TADs) in the C-terminal half. It also has an oxygen-dependent degradation (ODD) domain, which is required to degrade HIF-1alpha protein by the ubiquitin-proteasome pathway. In this study, we identified a new alternatively spliced variant of human HIF-1alpha mRNA, which lacked both exons 11 and 12, producing a frame shift and giving a shorter form of HIF-1alpha. In the corresponding protein, a part of the ODD domain, both TADs and the C-terminal NLS motif were missing. Expression of endogenous HIF-1alpha variant protein was identified using immunoprecipitation and immunoblotting methods. The expressed HIF-1alpha variant exhibited neither the activity of transactivation nor hypoxia-induced nuclear translocation. In contrast with HIF-1alpha, the variant was strikingly stable in normoxic conditions and not up-regulated to such an extent by hypoxia, cobalt ions or desferrioxamine. It was also demonstrated that the HIF-1alpha variant competed with endogenous HIF-1alpha and suppressed HIF-1 activity, resulting in the down-regulation of mRNA expression of hypoxia-inducible genes. The association of the variant and arylhydrocarbon receptor nuclear translocator in the cytoplasm may be related to the inhibition of HIF-1 activity. It is assumed that this isoform preserves the balance between aerobic and anaerobic metabolism by counteracting the overaction of HIF-1alpha.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing
  • Animals
  • Aryl Hydrocarbon Receptor Nuclear Translocator
  • Base Sequence
  • Blotting, Western
  • Cell Line
  • Cloning, Molecular
  • DNA Primers
  • DNA-Binding Proteins*
  • Electrophoretic Mobility Shift Assay
  • Exons*
  • Gene Expression Regulation / physiology
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Mice
  • Microscopy, Fluorescence
  • Precipitin Tests
  • Protein Isoforms / genetics*
  • Protein Isoforms / metabolism
  • Protein Isoforms / physiology
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Receptors, Aryl Hydrocarbon*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism
  • Transcription Factors / physiology


  • ARNT protein, human
  • Arnt protein, mouse
  • DNA Primers
  • DNA-Binding Proteins
  • HIF1A protein, human
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Protein Isoforms
  • RNA, Messenger
  • Receptors, Aryl Hydrocarbon
  • Transcription Factors
  • Aryl Hydrocarbon Receptor Nuclear Translocator