Role of NPC1L1 in regulating energy metabolism, nutrient utilization & weight gai

NPC1L1在调节能量代谢、营养利用中的作用

• 批准号: 7582894
• 负责人: PHILIP N HOWLES
• 金额: $ 35.44万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-30 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7582894
• 关键词: ADD-1 protein; Accounting; Acyl Coenzyme A; Adipose tissue; Affect; Affinity; Anabolism; Animal Feed; Animals; Atherosclerosis; Attention; Bile fluid; Biliary; Biological Assay; Body Weight; Caco-2 Cells; Cell Culture Techniques; Cells; Cholesterol; Cholesterol Esters; Chronic; Chylomicrons; Coenzyme A Ligases; Complement component C1s; Data; Development; Diabetes Mellitus; Diet; Dietary Fats; Dietary Fatty Acid; Disease; Eating; Emulsions; Energy Metabolism; Euglycemic Clamping; Excretory function; Extrahepatic; Fatty Acids; Fatty acid glycerol esters; Gene Deletion; Gene Silencing; Genes; Glucose; Glucose Clamp; Goals; Hepatic; Hepatocyte; Homeostasis; Hyperglycemia; Hyperlipidemia; In Vitro; Infusion procedures; Insulin; Insulin Resistance; Intestines; Knockout Mice; Lipids; Lipoproteins; Liver; Measures; Mediating; Metabolic; Metabolic Diseases; Metabolism; Methods; Micelles; Monitor; Morbidity - disease rate; Mucous Membrane; Mus; Muscle; Myocardium; Nutrient; Obesity; Pathway interactions; Pharmaceutical Preparations; Phenotype; Physiological; Pick Disease of the Brain; Plasma; Precipitation; Property; Proteins; Radiolabeled; Reducing diet; Relative (related person); Reporting; Research; Research Project Grants; Resistance; Risk; Rodent; Role; Safflower Oil; Saturated Fatty Acids; Solubility; Sucrose; Testing; Therapeutic; Time; Tissues; Tracer; Triglycerides; Unsaturated Fats; Unsaturated Fatty Acids; Weight; Weight Gain; Wild Type Mouse; absorption; base; bile salts; cholesterol absorption; cocoa butter; design; energy balance; ezetimibe; fatty acid analog; feeding; glucose metabolism; hypercholesterolemia; in vivo; inhibitor/antagonist; inorganic phosphate; insight; lipid metabolism; lipid transport; liver metabolism; mortality; novel; novel therapeutics; oxidation; polyunsaturated fat; prevent; protein expression; public health relevance; radiotracer; receptor; research study; response; saturated fat; uptake

DESCRIPTION (provided by applicant): The goal of this research is to understand the mechanistic relationship between dietary lipid absorption and overall metabolism. The drug ezetimibe lowers plasma cholesterol by blocking its absorption in the intestine, apparently by disrupting the pathway associated with NPC1L1 (Nieman-Pick disease, type C1-protein -like protein 1). Preliminary studies into other physiological effects of ezetimibe have revealed that postprandial intestinal lipoproteins from ezetimibe-treated mice are different in size and composition than those from control mice. Our results also show that loss of NPC1L1 function, through ezetimibe treatment or gene deletion, protects mice from diet-induced obesity and insulin resistance. Reduced fat absorption may account for part of the difference in weight gain, but additional mechanisms, including increased energy expenditure, may also confer protection against diabetes and obesity. The focus of this proposal is to determine the mechanism(s) responsible for these different phenotypes. In Specific Aim 1, ezetimibe-treated, Npc1l1-/-, and control mice will be fed high fat diets that are either well absorbed by each group (safflower oil based) or poorly absorbed by Npc1l1-/- and ezetimibe-treated mice (cocoa butter based). Weight gain, plasma glucose, and energy expenditure will be monitored to test the hypothesis that mechanisms in addition to reduced fat absorption contribute resistance to obesity and diabetes of drug-treated and knockout mice. Other experiments will examine the partitioning of dietary fat among high energy tissues such as adipose, muscle, heart and liver in these three groups of mice to test the hypothesis that NPC1L1 inactivation alters postprandial lipid delivery to and utilization by these tissues. Aim 1 will also determine if metabolic changes derive from increased activation of specific receptors in hepatocytes due to chronic cholesterol loss. Specific Aim 2 will use in vivo methods to determine if the difference in dietary triglyceride utilization by muscle, liver and adipose is caused by disruption of NPC1L1-dependent pathways in those tissues or if it is caused by altered chylomicron composition from decreased cholesterol and fatty acid absorption. The effect of NPC1L1 and ezetimibe on glucose metabolism by these tissues will also be specifically tested. Specific Aim 3 will identify the mechanism by which inhibiting cholesterol absorption reduces saturated fatty acid absorption without affecting absorption of unsaturated fatty acids. In vitro, cell culture, and in vivo experiments will test the hypothesis that unabsorbed cholesterol inhibits solubilization of saturated fatty acids by bile salt micelles causing their precipitation and excretion. Together, these studies will provide novel insights about underlying causes of obesity and diabetes, especially the relationship of fat absorption and metabolism with glucose metabolism and overall energy balance. These studies will also provide valuable information about mechanisms of action for existing drugs, with potential for the design and development of new therapeutic entities for treatment of the closely related diseases of hyperlipidemia, obesity and diabetes. PUBLIC HEALTH RELEVANCE: This research project will provide important new information about underlying causes of obesity and diabetes, especially the relationship of fat absorption and metabolism with glucose metabolism and overall energy balance. These studies will also provide valuable information about mechanisms of action for existing drugs, and will identify potential new targets for the design and development of new therapeutic entities for treatment of the closely related diseases of hyperlipidemia, obesity and diabetes.

描述（由申请人提供）：这项研究的目的是了解饮食脂质吸收和整体代谢之间的机械关系。药物二酰胺通过阻断与NPC1L1相关的途径（Nieman-Pick疾病，型C1蛋白质样蛋白1）的途径来降低血浆胆固醇。对Ezetimibe的其他生理作用的初步研究表明，来自Ezetimibe处理的小鼠的餐后肠脂蛋白的大小和组成与对照小鼠的大小和组成不同。我们的结果还表明，通过ezetimibe治疗或基因缺失，NPC1L1功能的丧失可保护小鼠免受饮食诱导的肥胖症和胰岛素抵抗。减少的脂肪吸收可能是体重增加差异的一部分，但包括增加能量消耗在内的其他机制也可能赋予针对糖尿病和肥胖症的保护。该提案的重点是确定负责这些不同表型的机制。在特定的目标1中，经埃泽替纤维处理的NPC1L1 - / - 和对照小鼠将被喂食高脂饮食，这些饮食要么被每个组（Safflower Oil基）充分吸收，要么由NPC1L1-/ - / - 和Ezetimibe培养的小鼠（基于Cocoa Butter）（基于Cocoa Butter）吸收不良。体重增加，血浆葡萄糖和能量消耗将受到监测，以检验以下假设：除了减少脂肪吸收外，机制还促进了药物治疗和敲除小鼠的肥胖和糖尿病的抗性。其他实验将检查这三组小鼠中脂肪，肌肉，心脏和肝等高能量组织中饮食脂肪的分配，以测试NPC1L1失活的假设，即这些组织会改变餐后脂质递送和利用这些组织。 AIM 1还将确定由于慢性胆固醇丧失而导致的肝细胞中特定受体的激活增加是否来自代谢变化。具体的目标2将使用体内方法来确定肌肉，肝脏和脂肪在饮食甘油三酸酯利用中的差异是由这些组织中NPC1L1依赖性途径的破坏引起的，还是由降解的胆固醇和脂肪酸吸收降低而导致的囊肿成分引起的。 NPC1L1和Ezetimibe对这些组织的葡萄糖代谢的影响也将得到特殊测试。具体目标3将确定抑制胆固醇吸收的机制，可减少饱和脂肪酸的吸收而不会影响不饱和脂肪酸的吸收。在体外，细胞培养和体内实验将检验以下假设：未吸收的胆固醇通过胆汁盐胶束抑制饱和脂肪酸的溶解，从而导致其沉淀和排泄。总之，这些研究将提供有关肥胖和糖尿病根本原因的新见解，尤其是脂肪吸收与代谢与葡萄糖代谢以及整体能量平衡的关系。这些研究还将提供有关现有药物作用机制的有价值的信息，并有可能设计和开发新的治疗实体，以治疗高脂血症，肥胖和糖尿病的紧密相关疾病。 公共卫生相关性：该研究项目将提供有关肥胖和糖尿病基本原因的重要新信息，尤其是脂肪吸收和代谢与葡萄糖代谢以及整体能量平衡的关系。这些研究还将提供有关现有药物作用机制的宝贵信息，并将确定潜在的新目标，以设计和开发新的治疗实体，以治疗高脂血症，肥胖和糖尿病的密切相关疾病。