NUTRITIONAL & HORMONAL REGULATION OF HEPATIC GENES

这项研究计划的目标是研究分子 甲状腺激素和营养因子的调节机制 肝脏特异性基因的表达。在这方面，我们目前正在 把我们的注意力集中在基因指定的第14点上。肝脏 斑点14mRNA浓度迅速增加(不到15分钟)，并且 在服用甲状腺后显著(超过10倍) 激素或碳水化合物喂养。因此，此响应可能表示 肝脏对这些刺激的主要作用。我们目前的工作 假说是该基因在两个不同的位置受 效应器；基因转录速率发生微小变化，但 主要的变化是由于转录后稳定性的增加 核前体点14mR-NA。 为了进一步研究Spot 14基因表达的调控，以下是 我们会进行研究。第一，诱导14号斑点基因表达 将在存在蛋白质合成抑制剂的情况下进行检测 这种反应是否真的是对激素和饮食的主要影响。 第二，这种调节将在#年的原代肝细胞培养中进行检测。 荷尔蒙和营养刺激的细胞作用部位将 得到确认。第三，点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，表达了几个 其他受甲状腺激素和碳水化合物调控的肝脏基因 摄食将被确定为测试转录后控制是否 14点基因的不寻常特征或受调控的共同特征 基因。进一步的研究将探索14号斑点mRNA之间的联系 与核基质的前体，即假定的RNA加工地点， 在荷尔蒙、饮食或发育变化期间。此外， 主要Spot 14转录本的转录后修饰将是 在这些州接受了检查。我们希望这些研究可以澄清 调控机制。最后，将开发一个细胞培养系统。 用DNA介导法检测分离到的Spot 14基因的功能 调职。随后，DNA序列的范围和性质至关重要 用于调控的基因将被定义为“体外”突变。这个系统 应为探索提供一个良好的模式体系的基础 荷尔蒙和饮食的基因调节，并可能提供关于 核糖核酸的核加工以及如何调控这一过程。

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.