Regulation of hypoxia-inducible factor 1 by glucose availability under hypoxic conditions

Kobe J Med Sci. 2008 Feb 8;53(6):283-96.

Abstract

Hypoxia-inducible transcription factor 1 (HIF-1), consisting of HIF-1 alpha and HIF-1 beta subunits, regulates the expression of a variety of genes involved in diverse adaptive processes in response to hypoxia. While oxygen availability regulates HIF-1 alpha by proteolytic degradation, some growth factors regulate HIF-1 alpha by protein synthesis in part through mammalian target of rapamycin complex 1 (TORC1) pathway. We herein report the role of nutrient availability on the regulation of HIF-1. A reduced availability of glucose, not amino acids, results in a decrease of the expression of HIF1-dependent genes and HIF-1 alpha protein in response to hypoxia. HIF-1 alpha mRNA expression was not significantly suppressed and DMOG, an inhibitor for proteasomal degradation of HIF-1 alpha, did not induce HIF-1 alpha protein expression under hypoxia combined with glucose depletion. In comparison to the effect in the presence of glucose, glucose depletion under hypoxia induced a much stronger activation of the AMP-dependent kinase pathway and phosphorylation of eIF2 alpha, and nearly complete inhibition of the TORC1 pathway. These findings imply that the reduced availability of glucose under hypoxia downregulates HIF-1 in part through the inhibition of HIF-1 alpha mRNA translation, which is occasionally observed in pathophysiological situations such as ischemic diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinase Kinases
  • Anti-Bacterial Agents / pharmacology
  • Aryl Hydrocarbon Receptor Nuclear Translocator / metabolism*
  • Cell Hypoxia
  • Cell Line
  • Cytosol / drug effects
  • Cytosol / metabolism
  • Eukaryotic Initiation Factor-2 / metabolism
  • Gene Expression Regulation
  • Glucose / metabolism*
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / genetics
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism*
  • Phosphorylation
  • Protein Biosynthesis
  • Protein Kinases / metabolism
  • Signal Transduction
  • TOR Serine-Threonine Kinases

Substances

  • ARNT protein, human
  • Anti-Bacterial Agents
  • Eukaryotic Initiation Factor-2
  • HIF1A protein, human
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Aryl Hydrocarbon Receptor Nuclear Translocator
  • Protein Kinases
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • AMP-Activated Protein Kinase Kinases
  • Glucose