Control of Gene Expression of Glutathione Peroxidase-1 and Other Selenoproteins in Rats and Cultured Cells
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In summary, there are six control points for gene expression. Studies with rats clearly indicate that tissue type, gender, and pregnancy/lactation all can have dramatic effects on transcription, but there is no evidence for Se regulation of transcription. Severe mineral deficiencies can elicit modest down-regulation of GPX1 transcription, apparently secondary to the primary deficiency. Expression of GPX1 does not appear to be controlled by nuclear RNA processing or rate of nuclear export. In the cytoplasm, the specific and unique control point for GPX1 expression is the regulation of GPX1 mRNA stability by Se status. In addition, the availability of Sec-tRNAøSec for translation clearly regulates protein synthesis of GPX1;this step in translation is the major control point for regulation of synthesis of the other selenoproteins, as the mRNA levels for the other selenoproteins are not appreciably down-regulated when Se status is marginal. Lastly, it appears that Se status has no effect on rates of selenoprotein turnover.
KeywordsGPX1 Activity Dietary Selenium SECIS Element GPX1 Expression Phospholipid Hydroperoxide Glutathione Peroxidase
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