Apolipoprotein AV and intestinal transport

载脂蛋白 AV 和肠道运输

• 批准号: 9242017
• 负责人: PATRICK TSO
• 金额: $ 36.41万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2020-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9242017
• 关键词: Affect; Animals; Ants; Apolipoproteins; Apolipoproteins B; Appearance; Bile fluid; Biliary; Blood Circulation; Cholesterol; Chronic; Chylomicrons; Clinical; Clinical Management; Communication; Coronary heart disease; Data; Diabetes Mellitus; Diet; Dose; Emulsions; Endoplasmic Reticulum; Enterocytes; Esterified Fatty Acids; Fatty Acids; Fatty acid glycerol esters; Gastrointestinal Physiology; Gastrointestinal tract structure; Glycerophosphates; Hepatic; Homeostasis; Human; Hypertriglyceridemia; Infusion procedures; Injectable; Intestines; Knock-out; Knockout Mice; Knowledge; Label; Left; Leucine; Lipids; Lipoproteins; Liver; Lymph; Lymphatic; Measures; Mediating; Membrane; Metabolism; Methionine; Molecular; Monoglycerides; Mus; Obesity; Organ; Outcome; Output; Partial Hepatectomy; Particle Size; Pathway interactions; Phospholipids; Physiology; Plasma; Process; Production; Proteins; Published Comment; Recombinants; Regulation; Research; Research Personnel; Risk Factors; Role; Signal Transduction; Small Intestines; Source; Testing; Time; Transport Vesicles; Triglycerides; Very low density lipoprotein; Vesicle Transport Pathway; absorption; apolipoprotein B-48; base; experimental study; fascinate; feeding; insight; interest; knockout animal; novel; particle; public health relevance; response; targeted treatment; uptake

 DESCRIPTION (provided by applicant): Coronary heart disease, diabetes, and obesity remain major clinical problems worldwide and elevated plasma triglyceride (TG) levels constitute an independent risk factor. Discovered in 2001, apolipoprotein AV (apoAV) is a protein synthesized and secreted by the liver and is found to be inversely proportional to plasma TG levels. Mice and humans lacking functional apoAV have markedly elevated plasma TG while mice with high expression of human apoAV have dramatically decreased plasma TG. Curiously, plasma concentrations of apoAV are extremely low compared with other apolipoproteins such as apoB and apoAI. It has fascinated investigators for years that such a low circulating apolipoprotein can exert such a profound effect on plasma TG. We believe we have some novel insight to this question and this involves apoAV's action on the formation and secretion of chylomicrons (CM) by the enterocytes. Our preliminary data show that: 1) apoAV knockout (KO) animals were significantly more efficient in the absorption and lymphatic transport of both triglyceride (TG) an cholesterol than WT animals; 2) apoAV-KO animals have shorter CM appearance time than WT animals; 3) apoAV-KO animals release more pre-CM transport vesicles (PCTV) from endoplasmic reticulum (ER) than WT animals; 4) apoAV-KO animals secrete more apoB48 (therefore more CM particles since there is one apoB48 per particle) into lymph than WT animals; 5) apoAV is associated with CM in lymph during active fat absorption; and 6) apoAV is present in bile. We hypothesize that apoAV secreted by the liver regulates the intracellular formation and secretion of chylomicrons by the enterocytes and this regulation is mediated via biliary delivery and uptake of apoAV from the intestinal lumen. We will test these hypotheses in two specific aims. AIM 1: To determine the molecular mechanisms underlying the increased lymphatic transport of TG and cholesterol by apoAV-KO mice. There are four subaims to investigate the molecular mechanism of how apoAV modulates the formation and secretion of CM by the small intestine. The role of apoAV in CM and VLDL pathways for the transport of esterified FA will be determined. Taking advantage of our ability to label and isolate intestinal CM, the role of apoAV on CM metabolism will also be studied. AIM 2: Using recombinant apoAV in apoAV-KO animals, we will determine the effect of restoring apoAV in the circulation on intestinal CM transport. We will determine the effect of restoring hepatic production of apoAV to knockout animals (thus restoring both circulating and biliary apoAV) on intestinal CM transport. Lastly, we will determine directly the role of biliary apoAV in the lumen of apoAV-KO animals on lipid and apolipoprotein secretion by the gut, and study the uptake and lymphatic transport of 35S methionine labeled apoAV by the intestine will be studied.

 描述(由申请人提供)：冠心病、糖尿病和肥胖症仍然是世界范围内的主要临床问题，血浆甘油三酯(TG)水平升高是一个独立的危险因素。载脂蛋白AV(ApoAV)于2001年被发现，是一种由肝脏合成和分泌的蛋白质，被发现与血浆TG水平成反比。缺乏功能性载脂蛋白AV的小鼠和人的血浆甘油三酯显著升高，而人载脂蛋白AV高表达的小鼠血浆甘油三酯显著降低。奇怪的是，与载脂蛋白B和载脂蛋白AI等其他载脂蛋白相比，载脂蛋白病毒的血浆浓度极低。多年来，如此低的循环载脂蛋白能对血浆甘油三酯产生如此深远的影响，这一点一直让研究人员着迷。我们相信我们对这个问题有了一些新的见解，这涉及到载脂蛋白病毒对肠上皮细胞乳糜粒(CM)的形成和分泌的作用。我们的初步数据显示：1)apoAV基因敲除(KO)动物的甘油三酯(TG)和胆固醇的吸收和淋巴转运明显高于WT动物；2)apoAV-KO动物的CM出现时间比WT动物短；3)apoAV-KO动物比WT动物释放更多的CM前转运小泡(PCTV)；4)apoAV-KO动物比WT动物分泌更多的apoB48(因此每个颗粒有更多的CM颗粒)进入淋巴；5)在脂肪吸收活跃的过程中，apoAV与淋巴中的CM有关；6)apoAV存在于胆汁中。我们推测，肝脏分泌的载脂蛋白病毒调节肠道细胞内乳糜粒的形成和分泌，这种调节是通过胆道转运和从肠腔摄取载脂蛋白病毒来实现的。我们将在两个具体目标上检验这些假设。目的1：探讨apoAV-KO小鼠甘油三酯和胆固醇淋巴转运增加的分子机制。研究载脂蛋白AV如何调节小肠CM的形成和分泌的分子机制有四个子目标。载脂蛋白AV在CM和VLDL途径中运输酯化FA的作用将被确定。利用我们标记和分离肠道CM的能力，我们还将研究apoAV在CM代谢中的作用。目的：将重组apoAV应用于apoAV-KO动物体内，观察恢复循环中apoAV对肠道CM转运的影响。我们将确定恢复剔除动物肝脏载脂蛋白AV的产量(从而恢复循环和胆道载脂蛋白AV)对肠道CM转运的影响。最后，我们将直接确定apoAV-KO动物肠腔内胆汁载脂蛋白对肠道脂质和载脂蛋白分泌的影响，并研究35S蛋氨酸标记的载脂蛋白在肠道中的摄取和淋巴转运。