Differential regulation of expression of cytosolic and mitochondrial thioredoxin reductase in rat liver and kidney

Lynne Kathryn Crosley, C. Méplan, Fergus Nicol, A. K. Rundlöf, E. S. J. Arnér, J. E. Hesketh, John Arthur

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)


Adequate supply of selenium (Se) is critical for synthesis of selenoproteins through selenocysteine insertion mechanism. To explore this process we investigated the expression of the cytosolic and mitochondrial isoenzymes of thioredoxin reductase (TrxR1 and TrxR2) in response to altered Se supply. Rats were fed diets containing different quantities of selenium and the levels of TrxR1 and TrxR2 protein and their corresponding mRNAs were determined in liver and kidney. Expression of the two isoenzymes was differentially affected, with TrxR1 being more sensitive to Se depletion than TrxR2 and greater changes in liver than kidney. In order to determine if the selenocysteine incorporation sequence (SECIS) element was critical in this response liver and kidney cell lines (H4 and NRK-52E) were transfected with reporter constructs in which expression of luciferase required read-through at a UGA codon and which contained either the TrxR1 or TrxR2 3'UTR, or a combination of the TrxR1 5' and 3'UTRs. Cell lines expressing constructs with the TrxR1 YUTR demonstrated no response to restricted Se supply. In comparison the Se-deficient cells expressing constructs with the TrxR2 3'UTR showed considerably less luciferase activity than the Se-adequate cells. No disparity of response to Se supply was observed in the constructs containing the different TrxR1 5'UTR variants. The data show that there is a prioritisation of TrxR2 over TrxR1 during Se deficiency such that TrxR1 expression is more sensitive to Se supply than TrxR2 but this sensitivity of TrxR1 was not fully accounted for by TrxR1 5' or YUTR sequences when assessed using luciferase reporter constructs. (c) 2007 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)178-188
Number of pages11
JournalArchives of Biochemistry and Biophysics
Issue number2
Early online date22 Jan 2007
Publication statusPublished - 15 Mar 2007


  • selenium
  • thioredoxin reductase
  • isozyme
  • expression
  • 3 ' UTR
  • selenocysteine insertion-sequence
  • glutathione-peroxidase gene
  • 3'-untranslated region
  • redox regulation
  • selenium deficiency
  • cDNA cloning
  • active-site
  • localization
  • purification
  • mechanism


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