NUTRITIONAL REGULATION OF SELENOENZYMES AND PROTEINS

本申请拟研究硒的营养调节作用- 含有酶和蛋白质。 其中以谷胱甘肽过氧化物酶（GPX）为最佳 动物体内存在的硒酶，因此这项研究将 主要关注GPX。 GPX活性水平迅速下降， 膳食硒缺乏，我们已经使用抗GPX抗体表明， GPX蛋白水平也呈指数和协调下降， 进行性缺硒 用克隆的GPX cDNA进行北方杂交证明 分析，我们最近已经表明，在饮食中的硒水平调节 GPX mRNA水平以及GPX活性和蛋白质水平，从而表明 动物的硒状态可以调节含硒酶，如GPX， 基因表达的转录水平。 这种监管机制 这可能是为什么大多数人的膳食硒需求量 高等动物，通常使用GPX作为指标来确定， 相似 在过去的十年里，越来越明显的是， 除GPX外，硒蛋白还存在于高等植物的组织中。 动物，但这些硒蛋白的性质和功能主要是 未知 与其他依赖微量饮食因素的物种一样， 为了充分发挥生物活性，这些物种应该进一步 表征了 因为活性测定、抗体或cDNA探针不被 通常可用于这些未表征的硒蛋白，我们的 先前开发的SDS/PAGE方法可用于鉴定和 定量75硒标记的这些硒蛋白的数量。 这将 允许对这些相对未表征的硒蛋白进行初步研究。 为了进一步了解硒的代谢，我们打算继续研究硒的代谢。 以下具体目标：1）确定硒状态对 GPX的表达（mRNA、蛋白质和酶活性水平） 真核生物，并进一步表征这一过程; 2）纯化， 进一步表征一种或多种未表征的哺乳动物， 硒蛋白 本研究的总体目标是更好地了解 硒蛋白和硒酶如GPX的营养调节。 这些知识可能会导致更好地了解营养 这可能会增加我们对硒的充分利用的理解。 在动物和人类健康中的作用。

This application proposes to study the nutritional regulation of selenium- containing enzymes and proteins. Glutathione peroxidase (GPX) is the best characterized selenoenzyme present in animals, and thus this research will have a major focus on GPX. GPX activity levels decrease rapidly during dietary Se deficiency, and we have used anti-GPX antibodies to show that GPX protein levels also fall exponentially and coordinately during progressive Se deficiency. Using a cloned GPX cDNA prove in Northern blot analysis, we have recently shown that the level of Se in the diet regulates the level of GPX mRNA as well as GPX activity and protein, thus suggesting that Se status of animals may regulate Se-containing enzymes such as GPX at the transcriptional level of gene expression. This regulatory mechanism maybe one of the major reasons why the dietary Se requirements for most higher animals, usually determined using GPX as an indicator, are so similar. In the last decade it has become increasingly clear that a number of selenoproteins in addition to GPX are present in the tissues of higher animals, but the nature and function of these selenoproteins are largely unknown. As with other species that are dependent on trace dietary factors for full biological activity, these species should be further characterized. Because activity assays, antibodies or cDNA probes are not generally available for these uncharacterized selenoproteins, our previously developed SDS/PAGE procedure can be used to identify and to quantitate 75Se-labeling of a number of these selenoproteins. This will allow initial studies on these relatively uncharacterized selenoproteins. To further our understanding of Se metabolism, we intend to pursue the following specific objectives: 1) to determine the effect of Se status on the expression of GPX (mRNA, protein and enzyme activity levels) in eukaryotes, and to further characterize this process; 2) to purify and to further characterize one or more of the uncharacterized mammalian selenoproteins. The overall objective of this research is to better understand the nutritional regulation of selenoproteins and selenoenzymes such as GPX. This knowledge may lead to a better understanding of the nutritional biochemistry of Se and it may increase our understanding of selenium's full role in animal and human health.