Insulin and hypoxia share common target genes but not the hypoxia-inducible factor-1alpha.
Both hypoxia and insulin induce common target genes, including vascular endothelial growth factors and several glycolytic enzymes. However, these two signals eventually trigger quite different metabolic pathways. Hypoxia induces glycolysis, resulting in anaerobic ATP production, while insulin increases glycolysis for energy storage. Hypoxia-induced gene expression is mediated by the hypoxia-inducible factor-1 (HIF-1) that consists of HIF-1alpha and the aromatic hydrocarbon nuclear translocator (Arnt). Hypoxia-induced gene expression is initiated by the stabilization of the HIF-1alpha subunit. Here we investigated whether insulin-induced gene expression also requires stabilization of HIF-1alpha. Our results indicate that hypoxia but not insulin stabilizes HIF-1alpha protein levels, whereas both insulin- and hypoxia-induced gene expression require the presence of the Arnt protein. Insulin treatment fails to inactivate proline hydroxylation of HIF-1alpha, which triggers recruitment of the von Hippel-Lindau protein and oxygen-dependent degradation of HIF-1alpha. Insulin-induced gene expression is inhibited by the presence of the phosphoinositide (PI) 3-kinase inhibitor LY294002 and the dominant negative mutant of the p85 subunit of PI 3-kinase, whereas hypoxia-induced gene expression is not. Pyrrolidine dithiocarbamate, a scavenger of H2O2, reduces insulin-induced gene expression but not hypoxia-induced gene expression. Although both hypoxia and insulin induce the expression of common target genes through a hypoxia-responsive element- and Arnt-dependent mechanism, insulin cannot stabilize the HIF-1alpha protein. We believe that insulin activates other putative partner proteins for Arnt in PI 3-kinase- and H2O2-dependent pathways.
Yim
Sujin
S
Department of Life Science, University of Seoul, Seoul 130-743, Korea.
Choi
Su Mi
SM
Choi
Youngyeon
Y
Lee
Naery
N
Chung
Jieun
J
Park
Hyunsung
H
D016475:3T3 Cells; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002867:Chromones / Q000494:pharmacology; D003035:Cobalt / Q000494:pharmacology; D004268:DNA-Binding Proteins; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005799:Genes, Dominant; D005982:Glutathione Transferase / Q000378:metabolism; D006019:Glycolysis; D006367:HeLa Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D000860:Hypoxia; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D008025:Ligases / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009025:Morpholines / Q000494:pharmacology; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010957:Plasmids / Q000378:metabolism; D011759:Pyrrolidines / Q000494:pharmacology; D012313:RNA / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon; D013859:Thiocarbamates / Q000494:pharmacology; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein
D000255:Adenosine Triphosphate; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D002867:Chromones; D003035:Cobalt; D004268:DNA-Binding Proteins; D005982:Glutathione Transferase; D006861:Hydrogen Peroxide; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007328:Insulin; D008025:Ligases; D008156:Luciferases; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011759:Pyrrolidines; D012313:RNA; D018336:Receptors, Aryl Hydrocarbon; D013859:Thiocarbamates; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; C497396:ARNT protein, human; C497397:Arnt protein, mouse; C497442:HIF1A protein, human; C020972:pyrrolidine dithiocarbamic acid; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C497446:VHL protein, human; C018021:cobaltous chloride