Hypoxia and hypoxia mimetics inhibit TNF-dependent VCAM1 induction in the 5A32 endothelial cell line via a hypoxia inducible factor dependent mechanism

Todd V. Cartee, Kellie J. White, Marvin Newton-West, Robert A. Swerlick

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Background: We previously reported that iron chelators inhibit TNFα-mediated induction of VCAM-1 in human dermal microvascular endothelial cells. We hypothesized that iron chelators mediate inhibition of VCAM-1 via inhibition of iron-dependent enzymes such as those involved with oxygen sensing and that similar inhibition may be observed with agents which simulate hypoxia. Objective: We proposed to examine whether non-metal binding hypoxia mimetics inhibit TNFα-mediated VCAM-1 induction and define the mechanisms by which they mediate their effects on VCAM-1 expression. Methods: These studies were undertaken in vitro using immortalized dermal endothelial cells, Western blot analysis, ELISA, immunofluorescence microscopy, quantitative real-time PCR, and chromatin immunoprecipitation. Results: Hypoxia and the non-iron binding hypoxia mimetic dimethyl oxallyl glycine (DMOG) inhibited TNFα-mediated induction of VCAM-1. DMOG inhibition of VCAM-1 was dose-dependent, targeted VCAM-1 gene transcription independent of NF-κB nuclear translocation, and blocked TNFα-mediated chromatin modifications of relevant elements of the VCAM-1 promoter. Combined gene silencing of both HIF-1α and HIF-2α using siRNA led to a partial rescue of VCAM expression in hypoxia mimetic-treated cells. Conclusion: Iron chelators, non-metal binding hypoxia mimetics, and hypoxia all inhibit TNFα-mediated VCAM-1 expression. Inhibition is mediated independent of nuclear translocation of NF-κB, appears to target TNFα-mediated chromatin modifications, and is at least partially dependent upon HIF expression. The absence of complete VCAM-1 expression rescue with HIF silencing implies an important regulatory role for an Fe(II)/α-ketoglutarate dioxygenase distinct from the prolyl and asparagyl hydroxylases that control HIF function. Identification of this dioxygenase may provide a valuable target for modulating inflammation in human tissues.

Original languageEnglish (US)
Pages (from-to)86-94
Number of pages9
JournalJournal of Dermatological Science
Issue number2
StatePublished - Feb 2012

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Dermatology


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