Adipose Differentiation Related Protein (ADFP), VLDL Biogenesis and Triacylglycer

脂肪分化相关蛋白 (ADFP)、VLDL 生物发生和三酰甘油

• 批准号: 8107687
• 负责人: BENNY Hung-Junn CHANG
• 金额: $ 23.24万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-15 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8107687
• 关键词: Adenoviruses; Adipose tissue; Affect; Animals; Apolipoproteins B; Attenuated; Biochemical; Biogenesis; Cardiac; Cardiac Myocytes; Cardiovascular Diseases; Cell Line; Cell model; Cells; Chronic; Complement; Cytosol; Disease; Endoplasmic Reticulum; Equilibrium; Fatty Liver; Gene Expression; Genes; Genetic; Goals; Half-Life; Heart; Hepatic; Hepatocyte; Homeostasis; Human; Hydrolysis; Inflammation; Knock-out; Knockout Mice; Label; Light; Lipids; Lipoproteins; Liver; Liver diseases; Membrane; Messenger RNA; Methods; Microsomes; Modeling; Molecular; Mus; Obesity; Organ; Output; Pathogenesis; Physiologic pulse; Play; Production; Protein Binding; Protein Deficiency; Proteins; Recombinants; Regulation; Role; Small Interfering RNA; Societies; Surface; Testing; Tissues; Triglycerides; Up-Regulation; Very low density lipoprotein; design; inhibitor/antagonist; microsomal triglyceride transfer protein; mouse model; non-alcoholic fatty liver; overexpression; perilipin; public health relevance; research study; tool; uptake

DESCRIPTION (provided by applicant): Adipose Differentiation Related Protein (ADFP), VLDL Biogenesis and Triacylglycerol Homeostasis Nonalcoholic fatty liver disease (NAFLD) is often a precursor to chronic liver diseases, and a predictor of cardiovascular disease. The hallmark of NAFLD is the presence of numerous lipid droplets (LDs) in the hepatocytes. Adipose differentiation related protein (ADFP) is the most abundant cytosolic protein that binds to the surface of these LDs. Its expression is upregulated in lipid infiltrated hepatocytes (in NAFLD). I generated ADFP deficient mice and found a 60% reduction in hepatic triacylglycerol (TG) in these mice compared to WT mice. The TG reduction is pronounced in the cytosol, but, paradoxically, TG is increased in the microsome fraction in ADFP deficient as compared with wildtype mice. Concomitantly, there is an increase in the amount of microsomal triglyceride transfer protein (MTP) at the protein level, but not mRNA level, and a increase in VLDL secretion in the ADFP deficient mice. The hepatic lipid uptake, production and utilization are not altered. In this application, I will pursue three specific aims: (1) to identify the molecular mechanism of ADFP deficiency-associated hepatic MTP protein upregulation, (2) to determine the interplay between MTP and ADFP in modulating hepatic TG homeostasis., and (3) to study Adfp deficiency in the heart. I will use hepatic cell lines, cardiomyocytes, primary hepatocytes, transformed Adfp deficient hepatic cells, ADFP deficient and MTP conditional knockout mice as models. I will also generate conditional Adfp targeting mice. I will apply a combination of pharmacological and molecular tools such as MTP inhibitor, siRNA and recombinant helper dependent adenovirus to suppress or augment gene expression in these model cells and animals. The ultimate objectives I want to achieve are (i) to determine the mechanism of MTP protein upregulation in ADFP deficiency, (ii) to find the mechanism of ADFP deficiency-associated hepatic TG reduction and cardiac TG elevation, (iii) to test the hypothesis that ADFP, with its involvement in LD formation and regulation may represent a cytosolic protein which compete with MTP for TG and negatively regulate VLDL secretion while causing hepatic steatosis when it is overexpressed, and (iv) to identify factors that affect liver and heart TG storage in Adfp deficiency. My long term goal is to understand the function of ADFP and other LD- associated proteins in the formation and maturation of LD and how this affects the regulation of hepatic and cardiac TG dynamics such as lipoprotein assembly and secretion, and lipid homeostasis in liver heart and other organs. PUBLIC HEALTH RELEVANCE: Adipose Differentiation Related Protein (ADFP), VLDL Biogenesis and Triacylglycerol Homeostasis Fatty liver is a common disease in the Western society, and it's prominent feature is the presence of lipid droplets (LDs) in the liver cells. Adipose Differentiation Related Protein (ADFP) is a protein found on the surface of LDs. In this application, I designed experiments to study the function of ADFP in controlling the liver, as well as whole body, lipid homeostasis (or inner balance).

描述(申请人提供)：脂肪分化相关蛋白(ADFP)，极低密度脂蛋白的生物发生和三酰甘油稳态非酒精性脂肪性肝病(NAFLD)通常是慢性肝病的先兆，也是心血管疾病的预测因子。非酒精性脂肪性肝病的特点是肝细胞内存在大量脂滴。脂肪分化相关蛋白(ADFP)是结合在这些LDs表面的最丰富的胞浆蛋白。它在脂质浸润性肝细胞(NAFLD)中表达上调。我建立了ADFP缺陷小鼠，发现与WT小鼠相比，这些小鼠的肝脏三酰甘油(TG)降低了60%。与野生型小鼠相比，ADFP缺陷型小鼠在细胞质中的TG显著降低，但在微粒体中的TG却升高。同时，ADFP基因缺陷小鼠的微粒体甘油三酯转运蛋白(MTP)在蛋白水平增加，而在mRNA水平不增加，VLDL的分泌增加。肝脏对脂肪的摄取、生产和利用没有改变。在这项应用中，我将追求三个特定的目标：(1)确定ADFP缺乏相关的肝脏MTP蛋白上调的分子机制；(2)确定MTP和ADFP在调节肝脏TG稳态中的相互作用；(3)研究ADFP缺乏在心脏中的作用。我将以肝细胞系、心肌细胞、原代肝细胞、转化的Adfp缺陷肝细胞、ADFP缺陷和MTP条件性基因敲除小鼠为模型。我还将生成有条件的Adfp以鼠标为目标。我将应用药理学和分子工具的组合，如MTP抑制剂、siRNA和重组辅助子依赖腺病毒来抑制或增强这些模型细胞和动物的基因表达。我想达到的最终目标是：(I)确定ADFP缺乏时MTP蛋白上调的机制，(Ii)找出ADFP缺乏相关的肝脏和心脏TG降低和升高的机制，(Iii)检验ADFP参与LD形成和调节的假设，即ADFP可能代表一种细胞质蛋白，与MTP竞争甘油三酯，并在其过度表达时负向调节VLDL的分泌，同时导致肝脏脂肪变性，以及(Iv)确定在ADFP缺乏时影响肝脏和心脏TG储存的因素。我的长期目标是了解ADFP和其他LD相关蛋白在LD的形成和成熟中的作用，以及这如何影响肝脏和心脏TG动力学的调节，如脂蛋白的组装和分泌，以及肝脏、心脏和其他器官的脂平衡。 与公众健康相关：脂肪分化相关蛋白(ADFP)，极低密度脂蛋白(VLDL)的生物发生和三酰甘油稳态脂肪肝是西方社会的一种常见病，其显著特征是肝细胞中存在脂滴(LDs)。脂肪分化相关蛋白(ADFP)是发现于LDS表面的一种蛋白质。在这项应用中，我设计了实验来研究ADFP在控制肝脏以及全身、脂质动态平衡(或内部平衡)方面的功能。