TISSUE-SPECIFICITY OF SELENOPROTEIN GENE-EXPRESSION IN RATS
TISSUE-SPECIFICITY OF SELENOPROTEIN GENE-EXPRESSION IN RATS
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DOI：
10.1016/0955-2863(95)80004-v
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发表时间：
1995-07-01
影响因子：
5.6
通讯作者：
WRAY, CD
中科院分区：
文献类型：
--
作者：
CHRISTENSEN, MJ;CAMMACK, PM;WRAY, CD
为了研究缺硒、适量和高硒摄入对硒蛋白基因表达和酶活性的组织特异性影响，给断奶大鼠饲喂低硒饲料或相同饲料中添加0.1 mg/kg或2.0 mg/kg硒的饲料91天。在生长方面没有观察到显著的差异。在肝脏中，细胞谷胱甘肽过氧化物酶、I型碘甲腺原氨酸5‘-脱碘酶和硒蛋白P基因的转录不受硒摄入量的影响。肝脏谷胱甘肽过氧化物酶和硒蛋白P的稳定表达水平高于肾脏。而碘甲状腺原氨酸5‘脱碘酶则相反。在肝脏中，缺硒使谷胱甘肽过氧化物酶基因表达减少89%，酶活性几乎丧失。甲状旁腺素5‘脱碘酶的mRNA和酶活性分别降低了69%和70%。在肾脏中，缺硒使谷胱甘肽过氧化物酶基因表达减少91%，酶活性几乎为零。碘甲状腺原氨酸5‘-脱碘酶的mRNA和酶活性分别下降了19%和62%。硒蛋白P基因在肾脏中的表达减少了50%，而在肝脏中的表达仅减少了14%。这两种补充剂之间唯一的差异是在肝脏中，当补硒水平超过营养适量时，碘甲状腺原氨酸5‘-脱碘酶活性会降低。因此，对于这些硒蛋白来说，信使核糖核酸的周转似乎是对硒摄入量最敏感的翻译前过程。此外，在缺硒时，硒蛋白mRNAs的稳定性也不同，这取决于所检查的组织。硒酶活性的百分比变化与其mRNA水平的变化并不总是相同的。这表明，包括翻译和蛋白质周转在内的其他过程可能决定了对膳食硒摄入量的反应所达到的酶活性的最终水平。
To investigate the tissue-specific effects of inadequate, adequate, and high selenium intake on selenoprotein gene expression and enzyme activity, weanling rats were fed a selenium-deficient diet or the same diet supplemented with 0.1 or 2.0 mg of selenium/kg of diet for 91 days. No significant differences in growth were observed. In liver, transcription of genes for cellular glutathione peroxidase, type I iodothyronine 5'-deiodinase, and selenoprotein P was unaffected by selenium intake. Steady-state levels of mRNA for glutathione peroxidase and selenoprotein P were higher in liver than in kidney. For iodothyronine 5' deiodinase in the opposite was true. In liver, selenium deficiency reduced glutathione peroxidase mRNA by 89% and virtually abolished enzyme activity. For iodothyronine 5' deiodinase, mRNA and enzyme activity were reduced 69 and 70%, respectively. In kidney, selenium deprivation decreased glutathione peroxidase mRNA by 91% and reduced enzyme activity to nearly zero. For iodothyronine 5'-deiodinase, decreases in mRNA and enzyme activity were 19 and 62%, respectively. Reductions in selenoprotein P mRNA were 50% in kidney but only 14% in liver. The only difference in the effects between the two supplements was in liver, where iodothyronine 5'-deiodinase activity was reduced by increasing the selenium supplement above a nutritionally adequate level. Hence, for these selenoproteins, mRNA turnover appears to be the pretranslational process most sensitive to selenium intake. In addition, selenoprotein mRNAs are stabilized differentially in selenium deficiency, depending upon the tissue examined. Percentage changes in the activity of selenoenzymes were not always the same as the changes in their mRNA levels. This suggests that other processes, including translation and protein turnover, may determine the ultimate level of enzyme activity attained in response to dietary selenium intake.