Elucidation of the role of myonectin in regulating lipid partitioning and metabolism

阐明肌连蛋白在调节脂质分配和代谢中的作用

• 批准号: 9470272
• 负责人: Hannah Little
• 金额: $ 4.4万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-16 至 2019-08-15
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9470272
• 关键词: Acute; Adipocytes; Adipose tissue; Affect; Biochemical Pathway; Biological Assay; Blood Circulation; Cardiovascular Diseases; Catabolism; Cause of Death; Cells; Clinical; Comorbidity; Complement 1q; Data; Deposition; Diet; Disease; Economic Burden; Exhibits; Family; Fasting; Fat-Restricted Diet; Fatty Acids; Fatty acid glycerol esters; Genetic; Genotype; Glucose; Goals; Healthcare Systems; Hepatocyte; High Fat Diet; Homeostasis; Hormones; Impairment; In Vitro; Knock-out; Knockout Mice; Label; Lead; Link; Lipids; Liver; Measures; Mediating; Metabolic; Metabolic Diseases; Metabolism; Modeling; Mus; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Pathway interactions; Peripheral; Phenotype; Physiological; Plasma Proteins; Play; Population; Prevalence; Process; Proteins; Radiolabeled; Recombinants; Regulation; Research; Role; Secondary to; Serum; Skeletal Muscle; TNF gene; Testing; Tissues; Triglycerides; United States; base; energy balance; enzyme activity; experimental study; fatty acid oxidation; glucose metabolism; in vivo; insight; lipid biosynthesis; lipid metabolism; lipoprotein lipase; loss of function; male; mouse model; novel; novel strategies; prevent; uptake

Project Summary Our lab has recently identified a family of 15 novel secreted plasma proteins, termed C1q/TNF-related proteins 1-15 (CTRP1-15), and we have found that many play prominent roles in regulating glucose and lipid metabolism (7-23). CTRP15, also termed myonectin, is a skeletal muscle-derived hormone and is the focus of this proposed project. Previous studies implicate myonectin as a postprandial hormone that facilitates lipid uptake from circulation into peripheral tissues (7). Preliminary experiments utilizing a whole-body knockout (KO) mouse model suggest that male KO mice challenged with a high fat diet (HFD) exhibit deficiencies in serum lipid clearance as well as differences in lipid deposition among liver and adipose tissues relative to their wildtype (WT) littermates. These data provide physiological evidence that myonectin is an important factor in regulating lipid metabolism to achieve whole-body energy homeostasis. The goal of the proposed project is to use HFD-fed KO mice as a model to study myonectin’s tissue-specific functions and mechanisms of action in vivo. Understanding how myonectin mediates tissue crosstalk to control metabolism will likely provide insights into how disruption of the metabolic network can lead to diseased states and perhaps reveal novel strategies to treat or prevent obesity-related metabolic disorders. The first specific aim is to elucidate the tissue-specific mechanisms underlying the impaired lipid clearance phenotype in HFD-fed KO mice. Radiolabeled lipids will be used to track acute lipid uptake and utilization in KO and WT mice to assess postprandial lipid partitioning. The contribution of alterations in lipoprotein lipase (LPL) activity to the high serum triglyceride levels in KO mice will be determined by measuring enzyme activity in different tissues derived from HFD-fed WT and KO mice. Finally, the ability of myonectin to directly modulate LPL activity will be analyzed by measuring enzyme activity in tissue explants derived from WT mice and treated with recombinant myonectin. The second specific aim is to determine, in a tissue-specific manner, the lipid metabolism processes that myonectin regulates. Fatty acid oxidation, de novo lipogenesis, and triglyceride synthesis will be evaluated in primary adipocytes and hepatocytes isolated from HFD-fed WT and KO mice to determine if alterations in any of these pathways contribute to the observed difference in lipid deposition. Additionally, primary cells will be isolated from WT mice and treated with recombinant myonectin before subjecting them to the same assays to determine if myonectin can directly affect these processes. Together, results from these studies will provide mechanistic insight at the tissue level underlying the impaired ability of KO mice to clear postprandial lipids and the difference in lipid partitioning. Additionally, these studies will reveal whether the observed phenotypes reflect the lack of direct myonectin action or are secondary to other alterations caused by myonectin deficiency.

项目摘要 我们的实验室最近发现了一个家族的15个新的分泌血浆蛋白，称为C1 q/TNF相关蛋白 1-15（CTRP 1 -15），我们已经发现，许多发挥突出的作用，在调节血糖和血脂 代谢（7-23）。CTRP 15，也称为肌粘连蛋白，是骨骼肌来源的激素，是免疫调节的焦点。 这个提议的项目。以前的研究表明肌联蛋白是一种餐后激素， 从循环中摄取到外周组织（7）。利用全身击倒的初步实验 (KO)小鼠模型表明，用高脂饮食（HFD）攻击的雄性KO小鼠表现出以下缺陷： 血清脂质清除率以及肝脏和脂肪组织中脂质沉积的差异， 野生型（WT）同窝仔。这些数据提供了生理学证据，表明肌粘连蛋白是一个重要的因素， 调节脂质代谢以实现全身能量稳态。拟议项目的目标是 使用HFD喂养的KO小鼠作为模型来研究肌连结蛋白的组织特异性功能和作用机制， vivo.了解肌粘连蛋白如何介导组织串扰以控制代谢可能会提供见解 代谢网络的破坏如何导致疾病状态，并可能揭示新的策略， 治疗或预防肥胖相关的代谢紊乱。第一个具体目标是阐明组织特异性 HFD喂养的KO小鼠中脂质清除表型受损的潜在机制。放射性标记的脂质将 用于跟踪KO和WT小鼠的急性脂质摄取和利用，以评估餐后脂质分配。 在KO中脂蛋白脂酶（LPL）活性的改变对高血清甘油三酯水平的贡献 将通过测量来自喂食HFD的WT和KO的不同组织中的酶活性来确定小鼠 小鼠最后，将通过测量酶活性来分析肌连结蛋白直接调节LPL活性的能力。 在来源于WT小鼠并用重组肌连蛋白处理的组织外植体中的活性。第二 具体的目的是以组织特异性的方式确定脂质代谢过程， 规范。将在初级研究中评价脂肪酸氧化、新生脂肪生成和甘油三酯合成。 从HFD喂养的WT和KO小鼠中分离的脂肪细胞和肝细胞，以确定这些细胞中的任何一个的改变 这些途径有助于观察到的脂质沉积差异。此外，将分离原代细胞 来自WT小鼠，并在对它们进行相同的测定之前用重组肌连蛋白处理， 确定myonectin是否可以直接影响这些过程。总之，这些研究的结果将提供 在组织水平上的机制洞察力是KO小鼠清除餐后脂质的能力受损的基础， 脂质分配的差异。此外，这些研究将揭示观察到的表型是否 反映缺乏直接的肌连蛋白作用或继发于肌连蛋白缺乏引起的其他改变。