Mechanism of Selenoprotein Synthesis

项目摘要/摘要 硒(Se)是一种重要的微量元素，长期以来一直以其抗氧化性能而闻名，其中大部分或全部是 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，以及介于两者之间的大多数生物过程。取得了相当大的进展 在我们对硒是如何被结合到硒蛋白中的理解上取得了进展，但我们的 知识仍然存在，包括当痕量硒在关键组织中优先保留和利用时 元素是有限的。硒半胱氨酸通过硒半胱氨酸裂解酶(Scly)在体内循环。有针对性的破坏 小鼠的Scly基因突变会导致代谢综合征，这种表型在雄性更明显 而不是雌性。有趣的是，来自临床试验的证据表明， 硒对血糖稳态的影响，表明在补充硒的人群中2型糖尿病的发病率更高 有足够的硒摄入量的男性，但不是女性。因此，Scly基因敲除小鼠模型可能具有 与适当的硒代谢对人类健康的重要性直接相关。这个项目的总体目标是 建议阐明SCLY反应的代谢综合征表型的机制基础 基因敲除，以及这种表型性别特异性的潜在原因。我们的长期目标是 研究是为了了解潜在的分子、细胞和组织特异性机制 调控硒分布和硒蛋白合成的调控途径。实现这些目标将 提供必要的信息，以加深我们对如何利用硒来实现最佳健康的理解。 我们的中心假设是Scly在组织和硒蛋白特异性的硒半胱氨酸循环中发挥作用， 有助于特定组织中的关键硒蛋白优先于硒的机制 微量元素含量有限。我们进一步假设，当SCLY 表达中断会导致代谢综合征。我们将通过以下几点来解决这一假设 特定目标：特定目标1：确定代谢途径和硒蛋白基因表达的变化 发生在雄性和雌性小鼠身上，对全身Scly KO的反应，其中哪一种受到管型的影响 和/或睾酮(TST)替代物。具体目标2：产生和表征组织特异性效应 雄性和雌性小鼠肝脏、胰岛和下丘脑Scly KO的变化及CAST和TST的影响 替补。具体目标3：建立细胞培养模型以进一步研究哪些变化 在AIMS 1和AIMS 2中发现的对雄性与雌性Scly KO小鼠的Met有贡献。这些研究将提供 对硒分布、硒蛋白合成和功能的新认识 能量代谢和代谢综合征中的硒循环。

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.