Mechanism of Selenoprotein Synthesis

项目总结/摘要 硒（Se）是一种重要的微量元素，长期以来因其抗氧化特性而闻名，其中大部分或全部都是 硒蛋白的作用。硒蛋白在生命的各个方面发挥作用，从早期发育到 与衰老有关的疾病，以及介于两者之间的大多数生物过程。了相当大的进展 在我们理解硒是如何被纳入硒蛋白，但在我们的主要差距， 知识仍然存在，包括硒是如何优先保留和利用在关键组织时，微量元素， 元素是有限的。硒代半胱氨酸通过硒代半胱氨酸裂解酶（Scly）在体内循环。靶向破坏 小鼠Scly基因的突变导致代谢综合征，这种表型在雄性中更为明显 比女性多。有趣的是，来自临床试验的证据表明， 硒对葡萄糖稳态的影响，表明补硒人群中2型糖尿病的发病率较高。 男性硒摄入量充足，但女性没有。因此，Scly敲除小鼠模型可能具有 与人体健康中适当硒代谢的重要性直接相关。这一总体目标 我们的建议是阐明代谢综合征表型对Scly反应的机制基础。 基因敲除，以及这种表型的性别特异性的原因。我们的长期目标 研究是为了了解潜在的分子，细胞和组织特异性机制背后的 硒分布和硒蛋白合成的调控途径。实现这些目标将 提供的信息是必不可少的，以进一步了解硒是如何利用最佳的健康。 我们的中心假设是Scly在硒代半胱氨酸的组织和硒蛋白特异性再循环中起作用， 有助于特定组织中的关键硒蛋白优先于硒的机制， 微量元素是有限的。我们进一步假设，当Scly 表达被破坏导致代谢综合征。我们将通过以下方式来解决这一假设 具体目标：具体目标1：确定代谢途径和硒蛋白基因表达的变化， 在雄性和雌性小鼠中发生，以响应全身Scly KO，以及其中哪些受CAST影响 和/或睾酮（TST）替代。具体目标2：生成和表征组织特异性 雄性和雌性小鼠的肝脏、胰岛和下丘脑Scly KO，以及CAST和TST- 更换.具体目标3：建立细胞培养模型，以进一步研究 在目的1和2中鉴定的基因有助于雄性与雌性Scly KO小鼠中的MetS。这些研究将提供 对硒的分布、硒蛋白的合成及硒蛋白的功能等方面的新认识 和硒在能量代谢和代谢综合征中的再循环。

PROJECT SUMMARY / ABSTRACT Selenium (Se) 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 Se is incorporated into selenoproteins, but major gaps in our knowledge remain, including how Se is preferentially retained and utilized in crucial tissues when the trace element is limiting. Selenocysteine is recycled in the body via selenocysteine lyase (Scly). Targeted disruption of the Scly gene in mice results in metabolic syndrome, with the phenotype being more pronounced in males than females. Interestingly, evidence from clinical trials suggests a gender specific effect of the influence of Se on glucose homeostasis, demonstrating a higher incidence of type 2 diabetes among Se supplemented men with an adequate Se intake but not among women. Thus, the Scly knockout mouse model may have direct relevance for the importance of proper Se metabolism in human health. The overall objectives of this proposal are to elucidate the mechanistic basis for the metabolic syndrome phenotype in response to Scly knockout, and the reasons underlying the sex-specific nature of this phenotype. The long-term goals of our research are to understand the underlying molecular, cellular and tissue-specific mechanisms behind the regulatory pathways governing Se distribution and selenoprotein synthesis. Achievement of these goals will provide information that is essential to furthering our understanding of how Se is utilized for optimum health. Our central hypothesis is that Scly functions in tissue- and selenoprotein-specific recycling of selenocysteine, contributing to mechanisms whereby crucial selenoproteins in specific tissues have priority on Se when the trace element is limiting. We further hypothesize that impaired synthesis of crucial selenoproteins when Scly expression is disrupted results in metabolic syndrome. We will address this hypothesis via the following specific aims: Specific Aim 1: Identify changes in metabolic pathways and selenoprotein gene expression that occur in male and female mice in response to whole body Scly KO, and which of these are affected by CAST and/or testosterone (TST)-replacement. Specific Aim 2: Generate and characterize effects of tissue-specific liver, pancreatic islet and hypothalamic Scly KO in male and female mice, and effects of CAST and TST- replacement. Specific Aim 3: Establish cell culture models to further investigate which of the changes identified in aims 1 and 2 contribute to MetS in male versus female Scly KO mice. These studies will provide new insights into the mechanisms of Se distribution, selenoprotein synthesis, and the functions selenoproteins and Se recycling in energy metabolism and metabolic syndrome.