Regulation of Carbohydrate Metabolism and Lipogenesis

碳水化合物代谢和脂肪生成的调节

• 批准号: 8621976
• 负责人: KOSAKU UYEDA
• 金额: --
• 依托单位: VA NORTH TEXAS HEALTH CARE SYSTEM
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-10-01 至 2016-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8621976
• 关键词: 14-3-3 Proteins; Affinity; Animal Model; Binding; Binding Proteins; Binding Sites; Biochemical; Carbohydrates; Carbon; Cell Culture Techniques; Cell Nucleus; Complex; Consumption; Crystallography; Cyclic AMP; Data; Development; Diabetes Mellitus; Diet; Dietary Carbohydrates; Disease; Eating; Elements; Ensure; Enzyme Gene; Enzymes; Epidemic; Famines; Fasting; Fatty Acids; Fatty acid glycerol esters; Food; Food Supply; Fractionation; Gene Expression; Genes; Genetic Transcription; Glucose; Goals; Hepatocyte; Hormonal; Importins; In Vitro; Ingestion; Ketone Bodies; Ketones; Knowledge; Laboratories; Life Style; Liver; Liver Extract; Malignant Neoplasms; Mammalian Cell; Mediating; Metabolic; Modeling; Molecular; Nuclear; Nuclear Export; Nuclear Import; Nutrient; Nutritional; Obesity; Organ; Overweight; Pharmaceutical Preparations; Phosphorylation; Physiological; Population; Prevention strategy; Process; Protein Binding; Protein Biosynthesis; Protein Dephosphorylation; Protein Phosphatase 2A Regulatory Subunit PR53; Protein phosphatase; Public Health; Pyruvate Kinase; Rattus; Regulation; Response Elements; Rodent; Role; Signal Transduction; Site; Source; Specificity; Sucrose; Testing; Time; Tissues; Triglycerides; Work; X-Ray Crystallography; abstracting; blood glucose regulation; carbohydrate metabolism; carbohydrate receptor; design; dietary excess; fatty acid metabolism; feeding; glucose sensor; hypertensive heart disease; in vivo; insight; lipid biosynthesis; novel; obesity treatment; oxidation; pressure; promoter; protein complex; public health relevance; response; three dimensional structure; transcription factor

DESCRIPTION (provided by applicant): Abstract Evolutionary pressure has favored mechanisms that allow the body to efficiently store nutrients as fat when food is abundant as a safeguard against occasional famine. With the dramatic changes in modern lifestyle including consumption of high carbohydrate and high fat foods, these mechanisms may now be contributing to a major epidemic of obesity in the US where the majority of the population is overweight. Glucose is not only a major fuel of all mammalian tissues but also a source of carbon for fat and protein synthesis. The liver is the principal organ responsible for the conversion of excess dietary carbohydrate into triglycerides. Ingestion of a high carbohydrate diet induces transcription of more than 20 genes involved in the conversion of glucose to storage fat. A transcription factor with specificity for carbohydrate responsive elements (ChRE) found in the promoters of multiple genes required for lipogenesis and which displayed appropriate dietary responsive regulation, was first identified in my laboratory following purification from rat liver and termed "carbohydrate response element binding protein, ChREBP". The complete process by which ChREBP is activated in response to excess carbohydrate in order to induce the transcription of lipogenesis enzyme genes and then is turned off is not yet fully understood. We have shown that glucose and cAMP have antagonistic roles in the regulation of ChREBP activities in part through phosphorylation and dephosphorylation of multiple sites on ChREBP. Glucose stimulates dephosphorylation of at least some of these sites by activating a Xu5P-stimulated protein phosphatase, Xu5P-PP2A. More recently we have found that the interaction of ChREBP with 14-3-3 is one of the most important steps in regulation of the nuclear localization of ChREBP. The phosphorylation of ChREBP enhances the binding to 14-3-3 and is essential for export of ChREBP out of the nucleus under fasting conditions. In addition, we found that certain metabolites in fasted liver, but not in fed liver, promote the interaction of ChREBP with 14-3-3, and thereby export of ChREBP out of the nucleus. We have identified the metabolites as ketone bodies. To characterize the metabolites further we propose to (1) determine the biochemical mechanism by which they promote the interaction between ChREBP and 14-3-3, (2) determine their physiological significance in inhibition of ChREBP activities in hepatocytes, and (3) investigate whether the metabolites are signaling compounds for regulation of the subcellular localization of ChREBP in response to nutrients and fasting in vivo. We also will investigate other glucose signaling compounds in high sucrose fed rat liver extracts that may increase importin ¿ binding and/or destabilize 14-3-3 binding to promote the nuclear import of ChREBP. X-ray crystallography will be used to investigate the mechanisms of metabolite regulation of ChREBP binding to 14-3-3 and importin ¿ at an atomic level.

描述（由申请人提供）： 抽象的进化压力具有首选的机制，可以使人体有效地将营养作为脂肪有效地存储为脂肪，因为食物富含偶然的饥荒。随着现代生活方式的巨大变化，包括消费高碳水化合物和高脂食品，这些机制现在可能导致大多数人口超重的美国肥胖症的主要流行。葡萄糖不仅是所有哺乳动物组织的主要燃料，而且是脂肪和蛋白质合成的碳来源。肝脏是负责将过量饮食中碳水化合物转化为甘油三酸酯的主要器官。摄入高碳水化合物饮食可诱导20多个参与葡萄糖转化为储存脂肪的基因的转录。具有特异性的转录因子在脂肪生成所需的多个基因的启动子中发现并显示出适当的饮食反应性调节，它首先在我的实验室中从大鼠肝脏中纯化并称为“碳水化合物响应元素的结合蛋白，chrebp”。为了诱导脂肪生成酶基因的转录，然后关闭脂肪生成的转录，尚未完全了解Chrebp激活Chrebp的完整过程。我们已经表明，葡萄糖和cAMP在Chrebp上多个位点的磷酸化和去磷酸化的一部分在调节Chrebp活性中具有拮抗作用。葡萄糖通过激活XU5P刺激的蛋白磷酸酶XU5P-PP2A来刺激至少其中一些位点的去磷酸化。最近，我们发现Chrebp与14-3-3的相互作用是调节Chrebp核定位的最重要步骤之一。 CHREBP的磷酸化增强了与14-3-3的结合，对于在禁食条件下将Chrebp从核中导出至关重要。此外，我们发现禁食的肝脏中的某些代谢产物（但未在肝脏中）促进Chrebp与14-3-3的相互作用，从而从细胞核中出口Chrebp。我们已经将代谢产物确定为酮体。 To characterize the metabolites further we propose to (1) determine the biochemical mechanism by which they promote the interaction between ChREBP and 14-3-3, (2) determine their physical significance in inhibition of ChREBP activities in hepatocytes, and (3) investigate whether the metabolites are signaling compounds for regulation of the subcellular localization of ChREBP in response to nutrients and fasting in vivo.我们还将研究高蔗糖喂养大鼠肝脏提取物中的其他葡萄糖信号传导化合物，这些化合物可能会增加进口素的结合和/或破坏14-3-3结合以促进Chrebp的核进口。 X射线晶体学将用于研究Chrebp结合到14-3-3和在原子水平上的代谢物调节的机理。