Tissue-specific regulation of the expression on individual glutathione peroxidases

决定硒蛋白活性的最有效参数是硒的有效性。然而，硒蛋白被提供硒的严格等级和有时独特的组织特异性都指向额外的调节机制。这些可以在翻译或转录水平发挥作用。mRNA的稳定性可能受到RNA结合蛋白的调节，这些蛋白自身对硒有反应，并且/或者与其他稳定mRNA/蛋白复合物的因子（tRNA、GTP）的亲和力不同。RNA结合蛋白通过其与两种选择的谷胱甘肽过氧化物酶cGPx和GI-GPx的3 '-非翻译区（带有Secis元件）的相互作用来鉴定。通过使用可获得的PHGPx启动子和待克隆的GI-GPx启动子，将发现与它们结合的应答元件和因子。两个随后缩短的启动子将偶联到报告基因，并在用所得构建体转染的来自不同组织的细胞中研究其活性。通过这些方法，应该找到至少两种谷胱甘肽过氧化物酶在硒限制条件下的mRNA的不同稳定性以及它们独特的组织分布的解释。

The most effective parameter determining the activity of selenoproteins is the availability of selenium. Both, the strict hierarchy by which selenoproteins are supplied with selenium and the sometimes unique tissue specificity, however, point to additional regulatory mechanisms. These may function at translational or trancriptional levels. mRNA stability may be regulated by RNA-binding proteins which by themselves respond to selenium and/or differ in their affinities to other factors (tRNA, GTP) stabilizing the putative mRNA/protein complex.Transcription may be regulated by tissue-specific transcription factors. RNA-binding proteins are to be identified by their interaction with the 3'-untranslated regions, bearing the Secis elements, of two selected glutathione peroxidases, cGPx and GI-GPx. Responsive elements and factors binding to them will be found by using the available PHGPx promoter and the GI-GPx promoter which is to be cloned. Both subsequently shortened promoters will be coupled to reporter genes and their activities studied in cells from different tissue transfected with the resulting constructs. With these approaches an explanation should be found for the different stability of the mRNA for at least two glutathione peroxidases under selenium limiting conditions as well as for their unique tissue distribution.