Insulin induces transcription of target genes through the hypoxia-inducible factor HIF-1alpha/ARNT.
Hypoxic stress induces the expression of genes associated with increased energy flux, including the glucose transporters Glut1 and Glut3, several glycolytic enzymes, nitric oxide synthase, tyrosine hydroxylase, erythropoietin and vascular endothelial growth factor (VEGF). Induction of these genes is mediated by a common basic helix-loop-helix-PAS transcription complex, the hypoxia-inducible factor-1alpha (HIF-1alpha)/aryl hydrocarbon nuclear translocator (ARNT). Insulin also induces some of these genes; however, the underlying mechanism is unestablished. We report here that insulin shares with hypoxia the ability to induce the HIF-1alpha/ARNT transcription complex in various cell types. This induction was demonstrated by electrophoretic mobility shift of the hypoxia response element (HRE), and abolished by specific antisera to HIF-1alpha and ARNT, and by transcription activation of HRE reporter vectors. Furthermore, basal and insulin-induced expression of Glut1, Glut3, aldolase A, phosphoglycerate kinase and VEGF was reduced in cells having a defective ARNT. Similarly, the insulin-induced activation of HRE reporter vectors and VEGF was impaired in these cells and was rescued by re-introduction of ARNT. Finally, insulin-like growth factor-I (IGF-I) also induced the HIF-1alpha/ARNT transcription complex. These observations establish a novel signal transduction pathway of insulin and IGF-I and broaden considerably the scope of activity of HIF-1alpha/ARNT.
Zelzer
E
E
Department of Molecular Genetics, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel.
Levy
Y
Y
Kahana
C
C
Shilo
B Z
BZ
Rubinstein
M
M
Cohen
B
B
D000818:Animals; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D015687:Cell Hypoxia; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005634:Fructose-Bisphosphate Aldolase / Q000096:biosynthesis / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D018336:Receptors, Aryl Hydrocarbon; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
C497396:ARNT protein, human; C497398:ARNT protein, rat; D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; C497444:Hif1a protein, rat; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007328:Insulin; D009687:Nuclear Proteins; D018336:Receptors, Aryl Hydrocarbon; D014157:Transcription Factors; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D007334:Insulin-Like Growth Factor I; D005634:Fructose-Bisphosphate Aldolase