Engineering glutamate metabolism

工程谷氨酸代谢

• 批准号: 7140636
• 负责人: MALCOLM WATFORD
• 金额: $ 20.98万
• 依托单位: RUTGERS, THE STATE UNIV OF N.J.
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-30 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7140636
• 关键词: alanine; aminoacid metabolism; ammonia; biological models; biotechnology; dietary aminoacid; dietary proteins; enzyme activity; gene expression; genetically modified animals; glutamate dehydrogenase; glutamates; glutamine; laboratory mouse; muscle cells; myosins; nitrogen metabolism; protein degradation; striated muscles; tissue /cell culture; transfection

DESCRIPTION (provided by applicant): The aim of this work is to produce a transgenic mouse model to study the role of glutamate availability in the regulation of nitrogen partitioning within the body. Glutamate makes up to 10-15% of dietary protein but most ingested glutamate is metabolized by the enterocytes of the small intestine. However, glutamate plays a major role in nitrogen metabolism within the body and, in skeletal muscle, is the direct precursor of glutamine which is utilized by a number of tissues (intestinal mucosa, liver, kidneys and immune cells) particularly in catabolic states. Supplemental glutamine is increasingly being given to a variety of patients, most notably those with impaired digestive function and/or muscle wasting. Since glutamine is synthesized from amino acids derived from muscle protein breakdown the rationale for glutamine supplementation is that it will decrease endogenous glutamine synthesis and thereby maintain muscle mass. In addition to glutamine, skeletal muscle also shows net production of alanine and ammonia but little is known about the regulation of this process. There is evidence that intracellular glutamate is limiting for glutamine synthesis in catabolic states and this work will test the hypothesis that glutamate availability is a prime determinant in the partitioning of nitrogen into glutamine, alanine and ammonia. A transgenic mouse model expressing glutamate dehydrogenase in skeletal muscle will be developed which will enable us to manipulate intramuscular glutamate levels through dietary means. We hypothesize that changing intramuscular glutamate content will change the ratio of glutamine, alanine and ammonia synthesized and released by this tissue in response to dietary amino acids and catabolic stress. The long term goals of the work are to formulate optimal delivery of amino acids and protein to enhance protein accretion and limit protein wasting in the treatment, and prevention, of disease.

描述（由申请人提供）：这项工作的目的是建立转基因小鼠模型来研究谷氨酸可用性在体内氮分配调节中的作用。谷氨酸占膳食蛋白质的 10-15%，但大多数摄入的谷氨酸是由小肠的肠细胞代谢的。然而，谷氨酸在体内氮代谢中发挥着重要作用，并且在骨骼肌中，是谷氨酰胺的直接前体，谷氨酰胺被许多组织（肠粘膜、肝脏、肾脏和免疫细胞）利用，特别是在分解代谢状态下。越来越多的患者开始补充谷氨酰胺，尤其是消化功能受损和/或肌肉萎缩的患者。由于谷氨酰胺是由肌肉蛋白分解产生的氨基酸合成的，因此补充谷氨酰胺的基本原理是，它将减少内源性谷氨酰胺合成，从而维持肌肉质量。除了谷氨酰胺之外，骨骼肌还显示出丙氨酸和氨的净产生，但人们对这一过程的调节知之甚少。有证据表明，细胞内谷氨酸限制了分解代谢状态下的谷氨酰胺合成，这项工作将检验谷氨酸可用性是将氮分配为谷氨酰胺、丙氨酸和氨的主要决定因素这一假设。将开发一种在骨骼肌中表达谷氨酸脱氢酶的转基因小鼠模型，这将使​​我们能够通过饮食手段控制肌内谷氨酸水平。我们假设改变肌内谷氨酸含量将改变该组织响应膳食氨基酸和分解代谢应激而合成和释放的谷氨酰胺、丙氨酸和氨的比例。这项工作的长期目标是制定氨基酸和蛋白质的最佳输送方式，以增强蛋白质积累并限制疾病治疗和预防中的蛋白质浪费。