Mechanism of Selenoprotein Synthesis

描述（由申请人提供）：硒是一种重要的微量元素，长期以来因其抗氧化特性而闻名，其中大部分或全部可归因于硒蛋白。硒蛋白在生命的各个方面发挥作用，从早期发育到与衰老相关的疾病，以及其间的大多数生物过程。在我们对硒如何被纳入硒蛋白的理解方面已经取得了相当大的进展，但我们的知识中仍然存在重大差距，包括当微量元素限制时，硒如何优先保留和利用在关键组织中。同样，当硒缺乏时，决定某些硒蛋白优先合成的机制仍然是个谜。硒代半胱氨酸通过硒代半胱氨酸裂解酶在体内循环，我们对这种酶在硒供应中的作用的了解很少。这个建议的总体目标是阐明硒半胱氨酸裂解酶的作用，有助于硒蛋白合成的层次结构，并调查硒转运受损时，由于硒蛋白P敲除硒半胱氨酸裂解酶的贡献。我们研究的长期目标是了解硒分布和硒蛋白合成调控途径背后的分子、细胞和组织特异性机制。这些目标的实现将提供信息，这是必不可少的，以进一步了解硒是如何利用最佳健康。我们的中心假设是硒代半胱氨酸裂解酶的功能在组织和硒蛋白特异性回收硒代半胱氨酸，有助于机制，使最重要的组织和硒蛋白优先硒时，微量元素是有限的。我们的中心假设将通过以下具体目的进行测试：1）表征硒代半胱氨酸裂解酶敲除对组织硒蛋白mRNA和蛋白质表达的影响，以及对解剖学、生理学、组织病理学、神经运动功能和神经行为的影响; 2）产生组合的硒代半胱氨酸裂解酶-硒蛋白P敲除小鼠，并如目的1所述进行表征;和3）表征与硒蛋白mRNA相关的mRNP，所述硒蛋白mRNA在目的1和2的条件下被保存或靶向降解。这些研究将为硒的分布、硒蛋白的合成以及避免硒蛋白mRNA的无义介导的衰变机制提供新的见解。

DESCRIPTION (provided by applicant): Selenium is an essential trace element long known for its antioxidant properties, most or all of which are attributable to selenoproteins. Selenoproteins function in all aspects of life, from early development through diseases associated with aging, and most of the biological processes in between. Considerable progress has been made in our understanding of how selenium is incorporated into selenoproteins, but major gaps in our knowledge remain, including how selenium is preferentially retained and utilized in crucial tissues when the trace element is limiting. Likewise, the mechanisms dictating preferential synthesis of some selenoproteins over others when selenium is deficient remain enigmatic. Selenocysteine is recycled in the body via selenocysteine lyase, and our knowledge about the role of this enzyme in selenium supply is minimal. The overall objectives of this proposal are to elucidate the role of selenocysteine lyase in contributing to the hierarchy of selenoprotein synthesis, and to investigate the contributions of selenocysteine lyase when selenium transport is impaired due to selenoprotein P knockout. The long-term goals of our research are to understand the underlying molecular, cellular and tissue-specific mechanisms behind the regulatory pathways governing selenium distribution and selenoprotein synthesis. Achievement of these goals will provide information that is essential to furthering our understanding of how selenium is utilized for optimum health. Our central hypothesis is that selenocysteine lyase functions in tissue- and selenoprotein-specific recycling of selenocysteine, contributing to mechanisms whereby the most crucial tissues and selenoproteins have priority on selenium when the trace element is limiting. Our central hypothesis will be tested via the following specific aims: 1) characterize the effects of selenocysteine lyase knockout on tissue selenoprotein mRNA and protein expression, and effects on anatomy, physiology, histopathology, neuromotor function and neurobehavior; 2) generate combined selenocysteine lyase- selenoprotein P knockout mice, and characterize as described for aim 1; and 3) characterize mRNPs associated with selenoprotein mRNAs that are either preserved or targeted for degradation under the conditions in aims 1 and 2. These studies will provide new insights into the mechanisms of selenium distribution, selenoprotein synthesis, and circumventing nonsense-mediated decay of selenoprotein mRNAs.