Differential regulation of glutathione peroxidase by selenomethionine and hyperoxia in endothelial cells

Abstract

We have studied the effect of selenomethionine (SeMet) and hyperoxia on the expression of glutathione peroxidase (GP) in human umbilical vein endothelial cells. Incubation of HUVEC with 1 x 10(-6) M SeMet for 24 h and 48 h caused a 65% and 86% increase in GP activity respectively. The same treatment did not result in significant changes in GP gene transcription and mRNA levels. Pactamycin, a specific inhibitor of the initiation step of translation, prevented the rise in GP activity induced by SeMet and caused an increase in GP mRNA in both cells grown in normal and SeMet-supplemented medium. Interestingly, SeMet supplementation stimulated the recruitment of GP mRNA from an untranslatable pool on to polyribosomes, so that the concentration of GP mRNA in polyribosomal translatable pools was 50% higher in cells grown in SeMet-supplemented medium than in cells grown in normal medium. On the other hand, cells exposed to 95% O2 for 3 days in normal medium showed a 60%, 394% and 81% increase in GP gene transcription rate, mRNA levels and activity respectively. Hyperoxia also stabilized GP mRNA. Hyperoxic cells grown in SeMet-supplemented medium did not show any change in GP gene transcription and mRNA levels, but expressed an 81% and 100% increase in GP activity and amount of GP mRNA associated with polyribosomes respectively, when compared with hyperoxic cells maintained in normal medium. Thus, GP appeared to be regulated post-transcriptionally, most probably co-translationally, in response to selenium availability, and transcriptionally and post-transcriptionally in response to oxygen.

Regulation of cellular glutathione peroxidase by different forms and concentrations of selenium in primary cultured bovine hepatocytes

“…Ebert et al [43] reported that GPx1 activity was enhanced 1.8-fold in bone marrow stromal cells that were cultured in the presence of 100 nM Se supplied as Na 2 SeO 3 . Incubation of human umbilical vein endothelial cells with 1 μmol/L of Se supplied as Se-Met for 24 h led to a 65% increase in GPx1 activity but did not result in a significant change in the level of GPx1 mRNA [44]. In this study, after reaching the maximal effect, higher Se supplementation led to dose-dependent decreasing trends of the mRNA level and activity of GPx1 in the hepatocytes treated with Se-Met, Na 2 SeO 3 or Se-Car (Figs.…”

Effects of 5 HIV Protease Inhibitors on Vasomotor Function and Superoxide Anion Production in Porcine Coronary Arteries

“…12 The effect of antioxidant SeMet on RTV-induced O 2 2 production was investigated. Because RTV was the most potent HIV PI, which caused vasomotor dysfunction and downregulation of eNOS expression, it was chosen as the …”

Chlorotyrosine promotes human aortic smooth muscle cell migration through increasing superoxide anion production and ERK1/2 activation

“…Mn (III) tetrakis (4-benzoic acid) porphyrin (MnTBAP) is a cell permeable superoxide dismutase (SOD) mimetic, which is an effective superoxide anion inhibitor [13]. Seleno-L-methionine (SeMet) is an effective antioxidant by increasing the activity of glutathione peroxidase [14].…”