Hypoxia induces hexokinase II gene expression in human lung cell line A549.

Academic Article

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.
  • Keywords

  • Cell Line, DNA-Binding Proteins, Deferoxamine, Gene Expression, Hexokinase, Humans, Hypoxia, Hypoxia-Inducible Factor 1, Hypoxia-Inducible Factor 1, alpha Subunit, Luciferases, Lung, Nuclear Proteins, Nucleic Acid Synthesis Inhibitors, Promoter Regions, Genetic, Protein Synthesis Inhibitors, RNA, Messenger, Respiratory System, Transcription Factors, Transfection
  • Digital Object Identifier (doi)

    Author List

  • Riddle SR; Ahmad A; Ahmad S; Deeb SS; Malkki M; Schneider BK; Allen CB; White CW
  • Start Page

  • L407
  • End Page

  • L416
  • Volume

  • 278
  • Issue

  • 2