NUTRITIONAL AND HORMONAL REGULATION OF HEPATIC GENES

哺乳动物生物体调节其遗传信息的表达 对营养和代谢信号的反应；然而，几乎没有 目前已知的与这些疾病相关的分子机制 流程。这项工作的长期目标是理解一个系统 新陈代谢的调节。这个系统包括酶的诱导。 碳水化合物增加对肝脏脂肪生成的催化作用 新陈代谢。我们重点研究了两个基因-L类型的丙酮酸激酶 (PK)和S14基因--通过增加转录激活 肝细胞的葡萄糖代谢。过去的工作已经定义了具体的 在这些基因的5‘侧翼区域发现的调控区 是控制的必要条件和充分条件。这些地区有一个共同的 包括两个元件的装置：碳水化合物响应元件 (家务)本身就能对升高的血糖做出反应 新陈代谢和增强反应的辅助因素部位。这个 Chore包含两个E盒基序(CACGTG)的独特排列，这两个基序是 由5个碱基对隔开。我们假设该元素充当 碳水化合物反应因子或复合体的结合部位。 了解这种转录因子的性质是第一个 这项工作的目标。这将通过以下方式解决：(1)确定 与序列CACGTG结合的因子USF是否为 碳水化合物反应复合体的成分；(2)分离和 克隆大鼠肝脏结合因子；以及(3) 鉴定碳水化合物反应复合体的其他成分 通过蛋白质相互作用屏幕参与基因调控。有了这个 信息，我们将继续研究，以探索 糖酵解升高时肝细胞中该因子的激活。 特别是，我们将探索磷酸化在这方面的作用。 进程。最后，我们将描述一种新型附件的特性 与PK和S14基因结合的因子，并决定这是否 因子参与接收来自其他生理因素的信号 这些基因的调节者。这些研究应该有助于破译 肝细胞可以感觉到糖酵解增加的信号过程 通过改变它的转录程序来回应，并作为一个榜样 用于高等真核生物中营养物质的转录调控。

Mammalian organisms regulate the expression of their genetic information in response to nutritional and metabolic signals; however, little is currently known regarding the molecular mechanisms involved in these processes. The long range goal of this work is to understand one system of metabolic regulation. This system involves the induction of enzymes catalyzing lipogenesis in the liver in response to increased carbohydrate metabolism. We have focused on two genes - the L-type pyruvate kinase (PK) and S14 genes - that are transcriptionally activated by increased glucose metabolism in the hepatocyte. Past work has defined specific regulatory regions found in the 5'-flanking region of these genes that are necessary and sufficient for control. These regions share a common arrangement including two elements: a carbohydrate response element (ChoRE) that by itself is capable of responding to increased glucose metabolism and an accessory factor site that enhances the response. The ChoRE contains a unique arrangement of two E box motifs (CACGTG) that are spaced by 5 base pairs. We hypothesize that this element serves as the binding site for a carbohydrate-responsive factor or complex. Understanding the nature of this transcriptional factor is the first objective of this work. This will be addressed by: (1) determining whether the factor USF, which binds to the sequence CACGTG, is a component of the carbohydrate-responsive complex; (2) isolating and cloning the factor binding to the ChoRE from rat liver; and (3) identifying other components of the carbohydrate-responsive complex involved in gene regulation using a protein interaction screen. With this information, we will pursue studies to explore the mechanism of activation of the factor in hepatocytes undergoing elevated glycolysis. In particular, we will explore the role of phosphorylation in this process. Finally, we will characterize the nature of a novel accessory factor that binds to both the PK and S14 genes and determine whether this factor is involved in receiving signals from other physiological regulators of these genes. These studies should help in deciphering the signaling process by which the hepatocyte can sense increased glycolysis and respond by changing its transcriptional program and serve as a model for transcriptional regulation by nutrients in higher eucaryotes.