Modulation of thioredoxin reductase-2 expression in EAhy926 cells: Implications for endothelial selenoprotein hierarchy

Michael S. Crane, Alexander F. Howie, John R. Arthur, Fergus Nicol, Lynne K. Crosley, Geoffrey J. Beckett

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Abstract

Background: We examined the expression of the mitochondrial selenoenzyme TrxR2 in the endothelial cell line EAhy926 under conditions known to modify its cytoplasmic counterpart TrxR1.

Methods: Cells were cultured with varying concentrations of selenite, sulforaphane or the Ca2+ ionophore A23187 for 72-h, prior to assay of TrxR concentration and activity. Further cultures underwent prolonged (7-day) Se-depletion before selenoprotein measurement.

Results: In Se-deficient cultures, neither Se, A23187 or sulforaphane affected TrxR2 concentration, while these treatments induced TrxR1 concentration (p<0.05). When co-incubated, optimal concentrations of Se (40 nM) and sulforaphane (4 mu M) only modestly increased TrxR2 protein (similar to 1.3-fold), compared with TrxR1 (similar to 4-fold). In Se-deficient cells, TrxR activity was unaffected by sulforaphane or A23187. Prolonged Se-depletion caused a comparatively small reduction in TrxR2 (66% TrxR2 retained) against TrxR1 and glutathione peroxidase-1 activity (38% and 17% retained, respectively).

Conclusions: The relative resistance of TrxR2 to Se-deprivation and induction by sulforaphane and A23187 suggests TrxR2 lies near the top of the selenoprotein hierarchy in EAhy926 cells and exhibits near maximum expression under a range of culture conditions. In Se deficiency an inactive (possibly truncated) TrxR1 is produced in response to stimulus by sulforaphane and A23187. General significance: These observations underpin a likely critical antioxidant role for TrxR2 and TrxR1 in the endothelium. (C) 2009 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)1191-1197
Number of pages7
JournalBiochimica et Biophysica Acta (BBA) - General Subjects
Volume1790
Issue number10
Early online date10 Jul 2009
DOIs
Publication statusPublished - Oct 2009

Keywords

  • mitochondrial thioredoxin reductase
  • endothelium
  • selenium
  • sulforaphane
  • selenoprotein hierarchy
  • oxidative stress
  • glutathione-peroxidase
  • selenium deficiency
  • atherosclerosis
  • induction
  • tissue
  • supplementation
  • dysfunction
  • activation
  • Mitochondrial thioredoxin reductase
  • Endothelium
  • Selenium
  • Sulforaphane
  • Selenoprotein hierarchy

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