HEPATIC GLUTAMINASE

谷氨酰胺在所有哺乳动物细胞中起着重要的生物合成作用。 糖尿病期间肝脏使用谷氨酰胺，糖尿病期间肾脏使用谷氨酰胺。 代谢性酸中毒和哺乳期的乳腺，也是一种 包括癌细胞在内的许多快速分裂细胞的主要呼吸燃料 细胞。哺乳动物组织中谷氨酰胺分解代谢的主要酶 是磷酸激活的谷氨酰胺酶的两种同工酶。肝型为 只在成人肝脏中发现，而另一种酶(肾型)是 在所有其他利用谷氨酰胺的组织中发现，包括胎儿肝脏和 肝癌细胞。所描述的工作的目的是描述和描述 了解磷酸激活的谷氨酰胺酶在体内的作用和调节 老鼠肝。 这项工作源于对肝脏谷氨酰胺酶活性的观察 在链脲佐菌素糖尿病期间增加了4倍。这种酶已经被 提纯的、针对它的特异性抗体，用于识别 推测为cdna。CDNAs的鉴定将通过比对得到证实。 在DNA和氨基酸序列中，mRNA和氨基酸序列的杂交选择 融合多肽的分析。该基因将被用来确定 MRNA相对丰度与肝脏转录速率的关系 正常大鼠和糖尿病大鼠肝脏谷氨酰胺酶基因。胞外 肝谷氨酰胺酶基因表达调控的刺激物 将使用分离的肝细胞和肝癌细胞进行鉴定。 该cDNA将用于鉴定编码肝型的基因组序列。 谷氨酰胺酶和其他利用酶的谷氨酰胺。分布情况： 肝脏和肾型谷氨酰胺酶(活性、蛋白质和mRNA)将 在不同的肝癌细胞和大鼠肝脏中不同时间测定 发展的各个阶段。将在细胞中分析染色质结构 显示出这两个基因的差异表达。这些系统提供了 研究组织特异性、激素和发育的独特模型 谷氨酰胺酶基因表达的调控。结果将提供 对为什么有两种酶以及它们的功能有价值的见解 属于不同的细胞类型。

Glutamine plays an important biosynthetic role in all mammalian cells. Glutamine is used by the liver during diabetes, the kidney during metabolic acidosis and the mammary gland during lactation, it is also a major respiratory fuel for many rapidly dividing cells including cancer cells. The major enzymes of glutamine catabolism in mammalian tissues are two isozymes of phosphate activated glutaminase. The liver type is found exclusively in adult liver while the other enzyme (kidney-type) is found in all other glutamine utilizing tissues, including fetal liver and hepatoma cells. The aim of the work described is to characterize and understand the role and regulation of phosphate activated glutaminase in rat liver. This work stems from the observation that hepatic glutaminase activity is increased 4-fold during streptozotocin diabetes. The enzyme has been purified, specific antibodies raised against it and used to identify a putative cDNA. The identify of the cDNA will be confirmed by comparison of the DNA and amino acid sequences, hybrid selection of mRNA and analysis of fusion peptide. The cDNA will be used to determine the relative abundance of mRNA and the rate of transcription hepatic glutaminase gene in liver from control and diabetic rats. Extracellular stimuli involved in the regulation of hepatic glutaminase gene expression will be identified using isolated hepatocytes and hepatoma cells. The cDNA will be used to identify genomic sequences encoding liver-type glutaminase and other glutamine utilizing enzymes. The distribution of liver- and kidney-type glutaminase (activity, protein and mRNA) will be determined in different hepatoma cells and in rat liver at different stages of development. Chromatin structure will be analyzed in cells showing differential expression of the two genes. These systems offer a unique model for the study of tissue-specific, hormonal and developmental regulation of glutaminase gene expression. The results will provide valuable insights into why there are two enzymes and what their functions are in the different cell types.