Selenoprotein gene expression during selenium-repletion of selenium-deficient rats
Selenoprotein gene expression during selenium-repletion of selenium-deficient rats
复制标题
DOI：
10.1007/bf02784076
复制
发表时间：
1996-03-01
影响因子：
3.9
通讯作者：
Hesketh, JE
中科院分区：
文献类型：
--
作者：
Bermano, G;Nicol, F;Hesketh, JE
以硒含量为20 μ g /kg体重的硒缺乏大鼠为模型，研究硒在肝脏和甲状腺中向特定硒蛋白分布的调控机制。肝脏注射硒16 ~ 32 h后，胞质谷胱甘肽过氧化物酶（cGSHPx）、磷脂氢过氧化物谷胱甘肽过氧化物酶（PHGSHPx）和碘甲状腺原氨酸5′-去碘酶（IDI）活性均有短暂性升高。然而，在甲状腺中，只有cGSHPx和PHGSHPx活性升高，而甲状腺中的IDI活性已经因缺硒而升高。这些反应是由于选择蛋白在新合成和/或现有mrna上的合成。在硒蛋白活性短暂增加后，甲状腺中的硒蛋白mrna增加了两倍和三倍。相比之下，肝脏中硒蛋白mRNA和酶活性发生平行变化，mRNA水平没有持续升高。器官差异表明，已知可诱导甲状腺IDI和mRNA的促甲状腺激素（TSH）浓度的增加可能控制所研究的所有甲状腺硒蛋白的mRNA，并且是硒供应有限时甲状腺硒蛋白保存的主要机制。
Selenium repletion of selenium-deficient rats with 20 mu g selenium/kg body weight as Na2SeO3 was used as a model to investigate the mechanisms that control the distribution of the trace element to specific selenoproteins in liver and thyroid. Cytosolic glutathione peroxidase (cGSHPx), phospholipid hydroperoxide glutathione peroxidase (PHGSHPx), and iodothyronine 5'-deiodinase (IDI) activities were all transiently increased in liver 16 to 32 h after ip injection with selenium. However, only cGSHPx and PHGSHPx activities increased in the thyroid where IDI activity was already increased by selenium deficiency. These responses were owing to synthesis of the seleoproteins on newly synthesised and/or existing mRNAs. The selenoprotein mRNAs in the thyroid gland were increased two- and threefold after the transitory increases in selenoprotein activity. Ln contrast, there were parallel changes in selenoprotein mRNAs and enzyme activities in the liver, with no prolonged rises in mRNA levels. The organ differences suggest that increased thryotrophin (TSH) concentrations, which are known to induce thyrodial IDI and mRNA, may control the mRNAs for all the thyroidal selenoproteins investigated and be a major mechanism for the preservation of thyroidal selenoproteins when selenium supplies are limited.