Apolipoprotein AV and intestinal transport

载脂蛋白 AV 和肠道运输

基本信息

批准号：
8914303
负责人：
PATRICK TSO
金额：
$ 37.92万
依托单位：
UNIVERSITY OF CINCINNATI
依托单位国家：
美国
项目类别：
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/8914303
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 Glycerides Glycerophosphates Hepatic Homeostasis Human Hypertriglyceridemia Infusion procedures 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 absorption apolipoprotein B-48 base fascinate feeding human APOA5 protein insight interest knockout animal novel particle public health relevance research study response therapeutic target uptake

项目摘要

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（申请人提供）：冠心病、糖尿病和肥胖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) 是一种由 2001 年发现的蛋白质合成和分泌的蛋白质。肝脏中的 TG 水平与血浆 TG 水平成反比。缺乏功能性 apoAV 的小鼠和人类的血浆 TG 显着升高，而具有高表达的人类 apoAV 的小鼠的血浆 TG 显着升高。奇怪的是，与其他载脂蛋白（如 apoB 和 apoAI）相比，apoAV 的血浆浓度极低，多年来，如此低的循环载脂蛋白对血浆 TG 产生如此深远的影响，这一点一直让研究人员着迷。对这个问题有一些新的见解，这涉及 apoAV 对肠上皮细胞乳糜微粒 (CM) 的形成和分泌的作用。我们的初步数据表明：1) apoAV 敲除 (KO)。与 WT 动物相比，动物在甘油三酯 (TG) 和胆固醇的吸收和淋巴转运方面更显着有效；2) apoAV-KO 动物比 WT 动物具有更短的 CM 出现时间；3) apoAV-KO 动物释放更多的前 CM 转运。 4) apoAV-KO 动物比 WT 动物分泌更多的 apoB48（因此存在更多的 CM 颗粒） apoB48（每个颗粒）比 WT 动物进入淋巴；5）apoAV 在主动脂肪吸收过程中与淋巴中的 CM 相关；6）我们发现肝脏分泌的 apoAV 通过以下方式调节细胞内乳糜微粒的形成和分泌。肠上皮细胞，这种调节是通过胆汁输送和肠腔摄取 apoAV 来介导的。我们将在两个具体目标中测试这些假设：确定。 apoAV-KO 小鼠增加 TG 和胆固醇淋巴转运的分子机制有四个子目标来研究 apoAV 如何调节小肠 CM 形成和分泌的分子机制 apoAV 在 CM 和 VLDL 中的作用。利用我们标记和分离肠道 CM 的能力，还将确定酯化 FA 的转运途径，并研究 apoAV 对 CM 代谢的作用：使用 AIM 2。在apoAV-KO动物中重组apoAV，我们将确定在循环中恢复apoAV对肠道CM运输的影响。我们将确定在敲除动物中恢复apoAV的肝脏产生（从而恢复循环和胆道apoAV）对肠道CM的影响。最后，我们将直接确定apoAV-KO动物管腔中胆汁apoAV对脂质和载脂蛋白分泌的作用。肠道，并研究肠道对35S蛋氨酸标记的apoAV的摄取和淋巴转运。