The effects of dietary selenium on translational control of protein synthesis

膳食硒对蛋白质合成翻译控制的影响

• 批准号: 8863770
• 负责人: MICHAEL T HOWARD
• 金额: $ 28.31万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-05-01 至 2019-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8863770
• 关键词: Affect; Amino Acids; Binding Proteins; Biochemical; Biochemical Pathway; Biological; Code; Codon Nucleotides; Complex; Data; Diabetes Mellitus; Diet; Dietary Selenium; Disease; Elements; Gene Expression; Genes; Genetic; Genome; Goals; Health; Human; Intake; Knowledge; Lead; Link; Location; Male Infertility; Malignant Neoplasms; Measurement; Messenger RNA; Methodology; Methods; Molecular; Mouse Strains; Mus; Mutation; Myopathy; Neurodegenerative Disorders; Nonsense-Mediated Decay; Open Reading Frames; Oxidative Stress; Pathway interactions; Physiological; Predisposition; Process; Production; Protein Biosynthesis; Protein Isoforms; Proteins; Regulation; Resolution; Ribosomes; Role; Selenium; Selenocysteine; Signal Transduction; Stress; Testing; Thinking; Thyroid Hormones; Tissues; Trans-Activators; Transcription Initiation; Translating; Translation Initiation; Translations; Untranslated Regions; Virus Diseases; deep sequencing; density; environmental change; feeding; genome-wide; immune function; improved; in vivo; mRNA Stability; public health relevance; research study; response; selenium deficiency; selenocysteine-tRNA; selenoprotein; tool; transcriptome sequencing

 DESCRIPTION (provided by applicant): The environmental element selenium (Se) is essential for human health in small amounts, but toxic at high levels. There is strong evidence that even small changes in Se status have multi-faceted effects on human health which include altered immune function and susceptibility to viral infections, biochemical stresses, cancer, and even diabetes. Many of the beneficial effects of Se can be attributed to selenoproteins; proteins containing Se in the form of the 21st amino acid selenocysteine (Sec). The diversity of substrates and biochemical pathways that selenoproteins act upon likely explains the multiple health effects associated with Se intake. Selenocysteine is incorporated into selenoproteins during translation by an unconventional mechanism involving Sec-tRNA decoding of UGA codons. This translational "redefinition" of UGA codons provides a unique mechanism by which selenoprotein expression may be controlled. Consequently, the regulation of selenoprotein synthesis is quite complex and likely involves control of selenocysteine incorporation efficiency and mRNA stability (due to nonsense mediated decay) in addition to regulation of transcription and translation initiation. Here we propose to systematically examine and clarify the molecular mechanisms of selenocysteine incorporation and control of selenoprotein synthesis using a combination of new deep-sequencing approaches and well established biochemical methods. Ribosome profiling (deep-sequencing of ribosome protected mRNA footprints) will be used to examine the location and density of ribosomes actively translating selenoprotein mRNAs in vivo (mouse tissues). From this information it will be possible to quantify both translation initiation and Sec incorporation efficiency in the context of controlled changes in diet or genetic backgrounds. Combined with measurements of mRNA abundance, this methodology provides an ideal tool to determine precisely how changing biological conditions affect selenoprotein synthesis. Preliminary data is presented which challenges conventional thinking about the mechanism of selenocysteine incorporation and how cis- and trans-acting factors regulate selenoprotein expression. In Aim 1, we propose to continue our studies of the mechanisms by which altered dietary selenium intake affects selenoprotein expression. In Aim 2, we propose to test hypothesis regarding the mechanism of Sec incorporation using genetically modified mice containing mutations in key cis- and trans-acting factors required for Sec incorporation. Finally, in Aim 3 we propose to examine the impact of altered selenoprotein expression on transcriptional and translational control of gene expression across the genome.

 描述（由申请人提供）：环境元素硒（Se）少量对人体健康至关重要，但高水平时有毒。有强有力的证据表明，即使是硒状态的微小变化也会对人类健康产生多方面的影响，包括免疫功能的改变和对病毒感染、生化应激、癌症甚至糖尿病的易感性。硒的许多有益作用可以归因于硒蛋白;以第21位氨基酸硒代半胱氨酸（Sec）形式含有硒的蛋白质。硒蛋白作用的底物和生化途径的多样性可能解释了与硒摄入相关的多种健康效应。硒代半胱氨酸在翻译过程中通过涉及UGA密码子的Sec-tRNA解码的非常规机制掺入硒蛋白中。UGA密码子的翻译“重新定义”提供了一种独特的机制，通过这种机制可以控制硒蛋白的表达。因此，硒蛋白合成的调节是相当复杂的，并且除了转录和翻译起始的调节之外，还可能涉及硒代半胱氨酸掺入效率和mRNA稳定性（由于无义介导的衰变）的控制。在这里，我们建议系统地检查和澄清硒半胱氨酸掺入和控制硒蛋白合成的分子机制，使用新的深度测序方法和完善的生化方法相结合。核糖体分析（核糖体保护的mRNA足迹的深度测序）将用于检查核糖体在体内（小鼠组织）主动翻译硒蛋白mRNA的位置和密度。从这些信息，它将是可能的，以量化的背景下，在饮食或遗传背景的控制变化的翻译起始和Sec的掺入效率。结合mRNA丰度的测量，这种方法提供了一个理想的工具，以精确地确定如何改变生物条件影响硒蛋白的合成。初步的数据提出了挑战传统的思维硒半胱氨酸掺入的机制，以及如何顺式和反式作用因子调节硒蛋白的表达。在目标1中，我们建议继续我们的机制，改变膳食硒摄入量影响硒蛋白表达的研究。在目标2中，我们建议使用含有Sec掺入所需的关键顺式和反式作用因子突变的转基因小鼠来检验关于Sec掺入机制的假设。最后，在目标3中，我们建议研究改变硒蛋白表达对整个基因组的基因表达的转录和翻译控制的影响。