Regulation of GPIHBP1-dependent and independent triglyceride clearance

GPIHBP1 依赖性和独立性甘油三酯清除率的调节

• 批准号: 9276103
• 负责人: BRANDON Scott Joseph DAVIES
• 金额: $ 38.13万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2021-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9276103
• 关键词: ANGPTL3 gene; ANGPTL4 gene; Address; Angiopoietins; Binding; Binding Proteins; Biological Assay; Blood Vessels; Blood capillaries; Capillary Endothelial Cell; Cardiac; Cell Culture System; Cell Culture Techniques; Clinical; Complex; Data; Deposition; Dyslipidemias; Employee Strikes; Endothelial Cells; Fatty Acids; Fenestrated Capillary; Fibrates; GPI Membrane Anchors; Goals; High Density Lipoproteins; Human; Hydrolysis; Hyperlipidemia; Hypertriglyceridemia; In Vitro; Individual; Inflammatory Response; Injection of therapeutic agent; Insulin Resistance; Knockout Mice; Knowledge; Lead; Life; Lipase; Lipids; Lipolysis; Liver; Mediating; Metabolic Diseases; Metabolic syndrome; Methods; Mission; Modeling; Mus; N-terminal; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Pathway interactions; Pharmaceutical Preparations; Phenotype; Plasma; Process; Proteins; Public Health; Recombinant Proteins; Regulation; Research; Serum; Skeletal Muscle; Surface; Testing; Therapeutic; Tissues; Triglyceride Metabolism; Triglycerides; United States National Institutes of Health; base; burden of illness; capillary; cardiovascular risk factor; design; improved; in vivo; in vivo Model; innovation; lipoprotein lipase; lipoprotein triglyceride; mouse model; novel; novel strategies; novel therapeutic intervention; prevent; restoration; uptake

PROJECT SUMMARY Clinical hypertriglyceridemia is common and is only partially responsive to available drugs. Conversely, excess triglyceride delivery to individual tissues can lead to skeletal muscle insulin resistance, cardiac lipotoxicity, or severe inflammatory responses. Given the importance of proper triglyceride delivery, it is imperative that we understand the mechanisms that regulate this process. Two proteins normally required for triglyceride clearance are lipoprotein lipase (LPL) and GPIHBP1. LPL is required for the actual hydrolysis of plasma triglyceides, liberating fatty acids for tissue uptake. The endothelial cell protein GPIHBP1 is required to properly localize LPL to the vascular lumen where lipolysis takes place. The long term goal of the proposed research is to understand and ultimately modulate the delivery of triglyceride-derived fatty acids to specific tissues. The objectives in this application are to advance our understanding of how the angiopoietin-like (ANGPTL) proteins, ANGPTL3 and ANGPTL4, modulate triglyceride clearance. ANGPTL3 and ANGPTL4 can both inhibit LPL in vitro, and ANGPTL3 or ANGPTL4 deficiency leads to lower plasma triglyceride levels. However, if and how ANGPTL3 and ANGPTL4 directly modulate LPL/GPIHBP1-mediated triglyceride clearance is not clear. Moreover, the plasma triglyceride levels in mice deficient in both GPIHBP1 and ANGPTL4 indicate that ANGPTL4 may regulate an uncharacterized, GPIHBP1-independent triglyceride clearance pathway. These issues will be addressed by pursuing two specific aims: 1) Define the mechanisms by which ANGPTL3 and ANGPTL4 modulate GPIHBP1-dependent triglyceride clearance; and 2) Identify novel mechanisms of GPIHBP1- independent triglyceride clearance. The studies in aim 1 employ cell culture–based binding and lipase activity assays, as well as in vivo injection of recombinant proteins and tissue-specific knockout mice to investigate how ANGPTL proteins interact with GPIHBP1/LPL complexes on the surface of endothelial cells. The second aim will address the remarkably lower triglycerides in Angptl4–/–Gpihbp1–/– mice. Triglyceride clearance and fatty acid uptake assays will be used to identify the tissues to which triglycerides get cleared. Expression, protein, and lipase activity analysis will be used to identify the proteins responsible for this clearance. The approaches in the proposed research are innovative because they combine standard methods with novel mouse models to address previously untested questions about how triglyceride clearance is regulated. The proposed studies are significant because they will elucidate how and where ANGPTL3 and ANGPTL4 modulate levels of functional LPL to influence triglyceride delivery and will uncover novel mechanisms of triglyceride clearance that do not require vascular LPL, ultimately permitting new strategies designed to prevent or treat dyslipidemia.

项目摘要 临床高胆固醇血症很常见，对现有药物仅部分反应。相反地， 过量的甘油三酸酯输送到各个组织可导致骨骼肌胰岛素抵抗、心脏胰岛素抵抗、心肌胰岛素抵抗、心肌细胞胰岛素抵抗、心肌细胞胰岛素抵抗和心肌细胞胰岛素抵抗。 脂毒性或严重炎症反应。考虑到适当的甘油三酯输送的重要性， 我们必须了解调控这一过程的机制。两种蛋白质通常 甘油三酯清除所需的是脂蛋白脂肪酶（LPL）和GPIHBP 1。LPL是必需的， 血浆甘油三酯的实际水解，释放脂肪酸供组织吸收。内皮细胞 蛋白GPIHBP 1是将LPL正确定位于发生脂解的血管腔所必需的。 拟议研究的长期目标是了解并最终调节 脂肪酸对特定组织的影响。本申请的目的是促进我们的 了解血管生成素样（ANGPTL）蛋白ANGPTL 3和ANGPTL 4如何调节 甘油三酯清除率ANGPTL 3和ANGPTL 4在体外均能抑制LPL，ANGPTL 3或ANGPTL 4在体外均能抑制LPL。 ANGPTL 4缺乏导致血浆甘油三酯水平降低。然而，如果以及如何ANGPTL 3和 ANGPTL 4直接调节LPL/GPIHBP 1介导的甘油三酯清除尚不清楚。而且 GPIHBP 1和ANGPTL 4缺陷小鼠的血浆甘油三酯水平表明ANGPTL 4可能 调节一种非特征性的、GPIHBP 1非依赖性甘油三酯清除途径。这些问题将 通过追求两个具体目标来解决：1）定义ANGPTL 3和ANGPTL 4 调节GPIHBP 1依赖性甘油三酯清除; 2）确定GPIHBP 1- 独立甘油三酯清除率。目的1中的研究采用了基于细胞培养的结合和脂肪酶 活性测定，以及体内注射重组蛋白和组织特异性敲除小鼠， 研究ANGPTL蛋白如何与内皮细胞表面的GPIHBP 1/LPL复合物相互作用， 细胞第二个目的将解决Angptl 4-/-Gpihbp 1-/-小鼠中显著较低的甘油三酯。 甘油三酯清除率和脂肪酸摄取测定将用于鉴定 甘油三酯被清除了表达、蛋白质和脂肪酶活性分析将用于鉴定 负责这种清除的蛋白质。本文的研究方法具有创新性 因为他们将联合收割机标准方法与新型小鼠模型相结合， 关于甘油三酯清除率如何调节的问题。这些研究是重要的，因为 他们将阐明ANGPTL 3和ANGPTL 4如何以及在何处调节功能性LPL水平， 影响甘油三酸酯的传递，并将揭示新的甘油三酸酯清除机制， 需要血管LPL，最终允许设计新的策略来预防或治疗血脂异常。