NUTRITIONAL & HORMONAL REGULATION OF HEPATIC GENES

这项研究计划的目标是调查分子 甲状腺激素和营养因子的作用机制， 特定肝脏基因的表达。 在这方面，我们目前 把我们的注意力集中在基因命名的14号点上。 肝 spot 14 mRNA的浓度非常迅速地增加（少于15分钟）， 甲状腺给药后显著（大于10倍） 激素或碳水化合物喂养。 因此，该响应可以表示 肝脏对这些刺激的主要作用。 我们目前的工作 有一种假说认为，该基因在两个不同的位点受到 效应子;基因转录速率发生微小变化，但 主要的变化是由于转录后的稳定性增加， Spot 14 mRNA的核前体。 为了进一步研究spot 14基因表达的调控， 将进行研究。 第一，诱导spot 14基因表达 将在存在蛋白质合成抑制剂的情况下进行检查， 这种反应是否真的是激素和饮食的主要影响。 第二，将在原代肝细胞培养物中检查调节， 激素和营养刺激的细胞作用部位将 得到证实。 第三，spot 14基因的转录活性将 在胎儿和新生儿发育期间进行检查，以确定何时 该基因的表达被激活。 第四，几种表达方式 其他受甲状腺激素和碳水化合物调节的肝脏基因 将确定喂养以测试转录后控制是否是 spot 14基因的不寻常特征或受调节基因的共同特征 基因. 进一步的研究将探索斑点14 mRNA与 前体与核基质，RNA加工的假定位点， 在荷尔蒙、饮食或发育变化期间。 此外该 初级斑点14转录物的转录后修饰将被 在这些国家检查。 我们希望这些研究可以阐明 调控机制。 最后，将开发细胞培养系统 利用DNA介导的基因工程技术检测spot 14基因的功能 转移 随后，DNA序列的范围和性质 用于调节的术语将由“体外”诱变来定义。 该系统 应该提供一个很好的模型系统，探索的基础， 激素和饮食基因调节，并可能提供线索， RNA的核加工以及如何调节这一过程。

The goal of this research proposal is to investigate the molecular mechanisms by which thyroid hormone and nutritional factors act to regulate the expression of specific hepatic genes. In this regard, we are currently focusing our attention on the gene designated spot 14. The hepatic concentration of spot14 mRNA increases very rapidly (less than 15 min) and dramatically (greater than 10-fold) following administration of thyroid hormone or carbohydrate feeding. Thus, this response may represent a primary effect in the liver to these stimuli. Our current working hypotheses is that this gene is regulated at two distinct sites by either effector; a minor change occurs in the rate of gene transcription, but the major change is due to a post-transcriptional increase in the stability of the nuclear precursor to spot 14 mRNA. To further study the regulation of spot 14 gene expression, the following studies will be performed. First, the induction of spot 14 gene expression will be examined in the presence of inhibitors of protein synthesis to test whether this response is truly a primary effect to hormone and diet. Second, the regulation will be examined in primary hepatocyte culture in which the cellular site of action of hormonal and nutritional stimuli will be confirmed. Third, the transcriptional activity of the spot 14 gene will be examined during fetal and neonatal development to determine when the expression of this gene is activated. Fourth, the expression of several other hepatic genes which are regulated by thyroid hormone and carbohydrate feeding will be determined to test whether post-transcriptional control is an unusual feature for the spot 14 gene or a common feature for regulated genes. Further studies will explore the association of the spot 14 mRNA precursor with the nuclear matrix, the presumed site of RNA processing, during hormonal, dietary or developmental changes. In addition, the post-transcriptional modification of the primary spot 14 transcript will be examined in these states. We hope that these studies may elucidate the mechanism of regulation. Finally, a cell culture system will be developed for testing the function of the isolated spot 14 gene by DNA-mediated gene transfer. Subsequently, the extent and nature of DNA sequences essential for regulation will be defined by 'in vitro' mutagenesis. This system should provide an excellent model system for exploring the basis of hormonal and dietary gene regulation and may provide clues regarding the nuclear processing of RNA and how this process can be regulated.