Cross-talk between the signals hypoxia and glucose at the glucose response element of the L-type pyruvate kinase gene.
The signals oxygen and glucose play an important role in metabolism, angiogenesis, tumorigenesis, and embryonic development. Little is known about an interaction of these two signals. We demonstrate here the cross-talk between oxygen and glucose in the regulation of L-type pyruvate kinase (L-PK) gene expression in the liver. In the liver the periportal to perivenous drop in O(2) tension was proposed to be an endocrine key regulator for the zonated gene expression. In primary rat hepatocyte cultures the expression of the L-PK gene on mRNA and on protein level was induced by venous pO(2), whereas its glucose-dependent induction occurred predominantly under arterial pO(2). It was shown by transient transfection of L-PK promoter luciferase and glucose response element (Glc(PK)RE) SV40 promoter luciferase gene constructs that the modulation by O(2) of the glucose-dependent induction occurred at the Glc(PK)RE in the L-PK gene promoter. The reduction of the glucose-dependent induction of the L-PK gene expression under venous pO(2) appeared to be mediated via an interference between hypoxia inducible factor-1 (HIF-1) and upstream stimulating factor at the Glc(PK)RE. The glucose response element also functioned as an hypoxia response element which was confirmed in cotransfection assays with Glc(PK)RE luciferase gene constructs and HIF-1alpha expression vectors. Furthermore, it was found by gel shift and supershift assay that HIF-1alpha and USF-1 or USF-2 could bind to the Glc(PK)RE. Our findings implicate that the cross-talk between oxygen and glucose might have a fundamental role in the regulation of several physiological and pathophysiological processes.
Krones
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A
Institut für Biochemie und Molekulare Zellbiologie, Georg-August-Universität, Humboldtallee 23, D-37073 Göttingen, Germany.
Jungermann
K
K
Kietzmann
T
T
D000818:Animals; D001158:Arteries; D015687:Cell Hypoxia; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D022781:Hepatocytes / Q000201:enzymology; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007150:Immunohistochemistry; D007700:Kinetics; D008099:Liver / Q000098:blood supply; D008156:Luciferases / Q000235:genetics; D008297:Male; D009687:Nuclear Proteins / Q000378:metabolism / Q000494:pharmacology; D010100:Oxygen / Q000097:blood / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D011770:Pyruvate Kinase / Q000032:analysis / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D020218:Response Elements; D015398:Signal Transduction; D013539:Simian virus 40 / Q000235:genetics; D014157:Transcription Factors; D014158:Transcription, Genetic; D014162:Transfection; D014680:Veins / Q000201:enzymology
D004268:DNA-Binding Proteins; C497444:Hif1a protein, rat; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D008156:Luciferases; D011770:Pyruvate Kinase; D005947:Glucose; D010100:Oxygen