ERK and calcium in activation of HIF-1

Ann N Y Acad Sci. 2002 Nov;973:448-53. doi: 10.1111/j.1749-6632.2002.tb04681.x.

Abstract

HIF-1 (hypoxia-inducible factor-1) is the main transcription factor responsible for increased gene expression in hypoxia. The oxygen-dependent regulation of HIF-1 activity occurs at multiple levels in vivo. The mechanisms regulating HIF-1alpha protein expression have been most extensively analyzed, but the ones modulating HIF-1 transcriptional activity remain unclear. Changes in the phosphorylation and/or redox status of HIF-1alpha certainly play a role. Here, we show that ionomycin could activate HIF-1 transcriptional activity in a way that is additive to the effect of hypoxia without affecting HIF-1alpha protein level and HIF-1 DNA binding capacity. In addition, a calmodulin dominant-negative mutant as well as BAPTA, an intracellular calcium chelator, inhibited the hypoxia-induced HIF-1 activation. These results indicate that elevated calcium in hypoxia could participate in HIF-1 activation. PD98059, an inhibitor of the ERK pathway, but not KN-93, an inhibitor of calmodulin kinases II and IV, also blocked HIF-1 activation by hypoxia and by ionomycin. Altogether, these results suggest that calcium and calmodulin would act upstream of ERK in the hypoxia signal transduction pathway leading to enhanced HIF-1 transcriptional activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calcium / physiology*
  • Calcium Signaling / physiology*
  • Carcinoma, Hepatocellular
  • Cell Hypoxia
  • Cloning, Molecular
  • DNA-Binding Proteins / drug effects
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Hypoxia-Inducible Factor 1
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Ionomycin / pharmacology*
  • Liver Neoplasms
  • MAP Kinase Signaling System / physiology*
  • Mitogen-Activated Protein Kinases / metabolism*
  • Nuclear Proteins / drug effects
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Plasmids
  • Transcription Factors / metabolism*
  • Transfection
  • Tumor Cells, Cultured

Substances

  • DNA-Binding Proteins
  • HIF1A protein, human
  • Hypoxia-Inducible Factor 1
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Nuclear Proteins
  • Transcription Factors
  • Ionomycin
  • Mitogen-Activated Protein Kinases
  • Calcium