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.
|Number of pages||7|
|Journal||Biochimica et Biophysica Acta (BBA) - General Subjects|
|Early online date||10 Jul 2009|
|Publication status||Published - Oct 2009|
- mitochondrial thioredoxin reductase
- selenoprotein hierarchy
- oxidative stress
- selenium deficiency
- Mitochondrial thioredoxin reductase
- Selenoprotein hierarchy