Hepatocyte Abca1, cholesterol trafficking, and lipid mobilization

肝细胞 Abca1、胆固醇运输和脂质动员

基本信息

批准号：
10063950
负责人：
JOHN S PARKS
金额：
$ 48.92万
依托单位：
WAKE FOREST UNIVERSITY HEALTH SCIENCES
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-07-23 至 2022-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10063950
关键词：
ADD-1 protein ATP binding cassette transporter 1 ATP-Binding Cassette Transporters Acute Address Affect Anabolism Apolipoprotein A-I Atherosclerosis BODIPY Cardiometabolic Disease Cardiovascular Diseases Catabolism Cell membrane Cells Cholesterol Cholesterol Homeostasis Complex Data Drops Endoplasmic Reticulum Endosomes Excretory function Fasting Fatty Liver Feces Funding Future Genetic Transcription Gluconeogenesis Hepatic Hepatocyte High Density Lipoprotein Cholesterol High Density Lipoproteins High Fat Diet Homeostasis Insulin Insulin Resistance Kinetics Knock-out Knockout Mice Knowledge Lipid Mobilization Lipids Lipoproteins Liver Liver Mitochondria Location Low Density Lipoprotein Receptor Low-Density Lipoproteins Lysophospholipids Lysosomes Mass Spectrum Analysis Measures Mediating Membrane Fluidity Membrane Proteins Messenger RNA Metabolic Metabolism Mitochondria Modeling Mus NPC1 gene Nuclear Protein Organelles Pathogenesis Phenotype Phospholipids Plant Roots Plasma Process Production Protein Export Pathway Recycling Regulation Research Respiration Role Sterols Stress Testing Tissues Transport Process United States National Institutes of Health Very low density lipoprotein Viral Work base cholesterol trafficking cholesteryl linoleate cholesteryl oleate fatty acid oxidation fluidity improved insight insulin signaling lipid biosynthesis lipid metabolism macrophage mitochondrial metabolism mouse model mutant novel particle programs promoter receptor expression respiratory enzyme reverse cholesterol transport trafficking uptake very low density lipoprotein triglyceride

项目摘要

Abstract- This R01 renewal seeks to continue the PI's creative, productive, and significant research program, which has enjoyed uninterrupted NIH funding since 1996, focused on lipid/lipoprotein metabolism in the pathogenesis of cardiovascular disease (CVD) and cardiometabolic disease (CMD). For over 15 years, the PI's research program has focused on ATP binding cassette transporter A1 (Abca1) and lipid and lipoprotein metabolism using tissue/cell-specific Abca1 knockout mice. Studies in hepatocyte-specific Abca1 knockout (HSKO) mice provided novel mechanistic insights into how hepatic Abca1 impacts the production and catabolism of all three major classes of plasma lipoproteins (VLDL, LDL, HDL) that contribute to CVD and CMD. Despite the massive (~80%) drop in plasma HDL relative to control mice, hyperlipidemic HSKO mice maintained macrophage reverse cholesterol transport and had decreased aortic root atherosclerosis compared to controls. HSKO mice also had increased plasma HDL cholesterol transport into the feces, decreased hepatic insulin signaling and de novo lipogenesis (DNL), increased mitochondrial respiration, increased LDL receptor expression, and increased hepatic VLDL triglyceride secretion. This unique phenotype was associated with diminished antegrade trafficking of lysosomal free cholesterol (FC) to the plasma membrane of hepatocytes, with no differences in total hepatic lipid mass between HSKO and control mice. Based on this work, our global hypothesis is that targeted deletion of hepatocyte Abca1 enhances hepatocyte retrograde FC redistribution from the plasma membrane to intracellular compartments, reprogramming insulin-mediated anabolism towards a coordinated catabolic program that reduces hepatic DNL, improves mitochondrial metabolism, and increases TG secretion, thereby decreasing hepatic steatosis when mice are stressed with a high-fat diet. This metabolic reprogramming in the absence of hepatic Abca1 results in a novel form of selective insulin resistance in HSKO mice, in which hepatic DNL is suppressed, but gluconeogenesis is appropriately downregulated by insulin. Future studies will address gaps in knowledge and barriers to progress, including: Specific aim 1) how Abca1 deletion alters FC distribution (or trafficking) among the plasma membrane, endoplasmic reticulum, and other organelles; Specific aim 2a) how insulin signaling and endoplasmic reticulum FC interact to activate Srebp1c; and Specific aim 2b) whether loss of Abca1 leads to increased mitochondria FC and/or lysophospholipid that improves mitochondrial respiration. Our proposed studies will build a more comprehensive and expansive model for Abca1 as a central control point of metabolic homeostasis and propel our previous 5-year discoveries in new directions, thereby advancing the field. Impact- Our studies will continue generating new discoveries regarding regulation of hepatic lipogenesis and the emerging role of Abca1 and FC trafficking in reprogramming hepatic lipid metabolism, a key contributor to CVD and CMD.

摘要-R01 更新旨在继续 PI 的创造性、富有成效和重要的研究项目，自 1996 年以来一直享有 NIH 不间断的资助，专注于脂质/脂蛋白代谢心血管疾病（CVD）和心脏代谢疾病（CMD）的发病机制。 15 年来，PI 研究计划重点关注 ATP 结合盒转运蛋白 A1 (Abca1) 以及脂质和脂蛋白使用组织/细胞特异性 Abca1 敲除小鼠进行代谢。肝细胞特异性 Abca1 敲除研究 (HSKO) 小鼠提供了关于肝脏 Abca1 如何影响肝脏生产和代谢的新机制见解。导致 CVD 和 CVD 的所有三大类血浆脂蛋白（VLDL、LDL、HDL）的分解代谢命令。尽管与对照小鼠相比，血浆 HDL 大幅下降（约 80%），但高脂血症 HSKO 小鼠与相比，维持巨噬细胞逆转胆固醇转运并减少主动脉根部动脉粥样硬化来控制。 HSKO 小鼠的血浆 HDL 胆固醇向粪便的转运也有所增加，肝脏胰岛素信号传导和从头脂肪生成 (DNL)、线粒体呼吸增加、低密度脂蛋白增加受体表达，并增加肝脏 VLDL 甘油三酯分泌。这种独特的表型是与溶酶体游离胆固醇（FC）向质膜的顺行运输减少有关肝细胞，HSKO 和对照小鼠之间的总肝脂质质量没有差异。基于此工作中，我们的总体假设是肝细胞 Abca1 的靶向删除会增强肝细胞逆行 FC 从质膜重新分布到细胞内区室，重新编程胰岛素介导的合成代谢朝向协调的分解代谢程序，减少肝脏 DNL，改善线粒体代谢，并增加 TG 分泌，从而在小鼠受到压力时减少肝脏脂肪变性高脂肪饮食。这种在肝脏 Abca1 缺失的情况下的代谢重编程导致了一种新形式的 HSKO 小鼠的选择性胰岛素抵抗，其中肝脏 DNL 受到抑制，但糖异生作用受到抑制胰岛素适当下调。未来的研究将解决知识差距和障碍进展，包括：具体目标 1) Abca1 删除如何改变 FC 在质膜、内质网和其他细胞器；具体目标 2a) 胰岛素信号传导和内质网 FC 相互作用激活 Srebp1c；具体目标 2b) Abca1 丢失是否会导致增加线粒体 FC 和/或溶血磷脂，改善线粒体呼吸。我们提出的研究将为 Abca1 作为代谢的中心控制点建立一个更全面和更广泛的模型稳态并推动我们之前 5 年的发现朝着新的方向发展，从而推动该领域的发展。影响-我们的研究将继续产生有关肝脏脂肪生成调节和 Abca1 和 FC 运输在重编程肝脂质代谢中的新作用，是肝脂质代谢的一个关键因素 CVD 和 CMD。