title: Hypoxia induces hexokinase II gene expression in human lung cell line A549.
abstract: During adaptation to hypoxic and hyperoxic conditions, the genes involved in glucose metabolism are upregulated. To probe involvement of the transcription factor hypoxia-induced factor-1 (HIF-1) in hexokinase (HK) II expression in human pulmonary cells, A549 cells and small-airway epithelial cells (SAECs) were exposed to stimuli such as hypoxia, deferoxamine (DFO), and metal ions. The largest increase in HK-II (20-fold for mRNA and 2.5-fold for enzymatic activity) was observed in A549 cells when exposed to DFO. All stimuli selectively increased the 5.5-kb rather than 4-kb transcript in A549 cells. Cycloheximide and actinomycin D inhibited these responses. In addition, cells were transfected with luciferase reporter constructs driven by the full-length HK-II 5'-regulatory region (4.0 kb) or various deletions of that region. A549 cells transfected with the 4.0-kb construct and exposed to hypoxia or DFO increased their luciferase activity 7- and 10-fold, respectively, indicating that HK-II induction is, at least in part, due to increased gene transcription. Sixty percent of the inducible activity of the 4.0-kb construct was shown to reside within the proximal 0.5 kb. Additionally, cotransfection with a stable HIF-1 mutant and the 4.0-kb promoter construct resulted in increased luciferase activity under normoxic conditions. These results strongly suggest that HK-II is selectively regulated in pulmonary cells by a HIF-1-dependent mechanism.
authors.affiliation: Department of Pediatrics, National Jewish Medical and Research Center, Denver, Colorado 80206, USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Riddle
authors.forename: A
authors.initials: A
authors.lastname: Ahmad
authors.forename: S
authors.initials: S
authors.lastname: Ahmad
authors.forename: S S
authors.initials: SS
authors.lastname: Deeb
authors.forename: M
authors.initials: M
authors.lastname: Malkki
authors.forename: B K
authors.initials: BK
authors.lastname: Schneider
authors.forename: C B
authors.initials: CB
authors.lastname: Allen
authors.forename: C W
authors.initials: CW
authors.lastname: White
mesh_terms: D002460:Cell Line; D004268:DNA-Binding Proteins / Q000494:pharmacology; D003676:Deferoxamine / Q000494:pharmacology; D015870:Gene Expression; D006593:Hexokinase / Q000235:genetics*; D006801:Humans; D000860:Hypoxia / Q000201:enzymology* / Q000235:genetics*; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008156:Luciferases / Q000378:metabolism; D008168:Lung / Q000201:enzymology* / Q000473:pathology; D009687:Nuclear Proteins / Q000494:pharmacology; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D012137:Respiratory System / Q000201:enzymology / Q000473:pathology; D014157:Transcription Factors; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D014157:Transcription Factors; D008156:Luciferases; D006593:Hexokinase; D003676:Deferoxamine