Mechanisms of cytoplasmic lipid droplet regulation in the intestine

肠道细胞质脂滴调节机制

• 批准号: 9121995
• 负责人: Meredith H Wilson
• 金额: $ 5.43万
• 依托单位: CARNEGIE INSTITUTION OF WASHINGTON, D.C.
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2019-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9121995
• 关键词: Accounting; Acute; Address; Adipocytes; Autophagocytosis; Biological Assay; Biological Models; Blood; Blood Circulation; Brain; Cardiovascular Diseases; Cell Line; Cholesterol Esters; Chronic; Chylomicrons; Data; Detection; Development; Dietary Fats; Dietary Fatty Acid; Enterocytes; Enzymes; Epithelial Cells; Esthesia; Exhibits; Exposure to; Fatty acid glycerol esters; Fishes; Goals; High Fat Diet; Hour; Human; Hypertriglyceridemia; Individual; Ingestion; Intestines; Label; Larva; Lipase; Lipids; Lipolysis; Lipoproteins; Maintenance; Mediating; Metabolic syndrome; Methods; Modeling; Mus; Oral; Organelles; Phospholipids; Population; Prevention; Prevention strategy; Process; Production; Proteins; Regulation; Risk Factors; Role; Serum; Source; Surface; System; Taste Buds; Taste Perception; Testing; Transgenic Organisms; Triglycerides; Variant; Work; Zebrafish; absorption; base; design; disorder risk; feeding; in vivo; in vivo imaging; lipid metabolism; monolayer; novel; perilipin; protein expression; public health relevance; relating to nervous system; research study; response; tool

 DESCRIPTION (provided by applicant): Elevated postprandial levels of triglyceride-rich lipoproteins (TRL) in the circulation are a risk factor for cardiovascular disease. Following a meal, chylomicrons produced by the intestine contribute prominently to circulating triglyceride (TG) levels, and production is primarily determined by the amount of fat ingested and absorbed. However, growing evidence suggests the intestine can actively regulate the rate of postprandial chylomicron production in part through transient TG storage and delayed export. Further, individuals with metabolic syndrome often exhibit hyperchylomicronemia. Thus, misregulation of intestinal TG storage and turnover likely contributes to disease risk. Intestinal enterocytes absorb and package dietary fatty acids into TG that is exported via chylomicrons or stored in cytoplasmic lipid droplets (LD). LDs are subcellular organelles composed of a core of TG and cholesterol esters surrounded by a monolayer of phospholipids and a variety of proteins, including perilipins. Intestinal LDs are dynamic storage compartments; they increase in number and size in the hours following a high-fat meal, but are nearly depleted 12-14 hours later in the absence of another meal. However, if a subsequent meal is consumed before the stored TG is depleted, it is rapidly exported in chylomicrons, suggesting that LD turnover is regulated. Despite the implications of intestinal LD regulation on postprandial serum TG levels, the mechanisms governing enterocyte LD regulation are poorly characterized. The overall goal of this proposal is to elucidate the cellular mechanisms regulating the maintenance and turnover of intestinal LDs following both an acute high-fat meal and in response to re- feeding. These studies will capitalize on the powerful transgenic and in vivo imaging opportunities afforded by the zebrafish model vertebrate system. Aim 1 of this proposal will determine whether LDs in enterocytes undergo rapid lipolysis by neutral lipases in response to re-feeding or are degraded by autophagy-mediated lipolysis. In Aim 2, the role of the LD-associated protein perilipin-2 in regulating intestinal LD storage and turnover will be explored. Human variants of perilipin-2 that are associated with favorable lipoprotein profiles will be evaluated to determine whether they alter intestinal LD dynamics. Aim 3 will establish whether zebrafish detect fat as a taste sensation and if this results in neural activation that is sufficient to elicit LD breakdown and chylomicron release in the fish, as has been suggested by human studies. Understanding intestinal regulation of lipid storage and lipoprotein production is imperative for development of strategies for the prevention and treatment of hypertriglyceridemia. Collectively, the proposed experiments will elucidate the cellular mechanisms regulating the storage and turnover of lipid in the intestine, produce novel methods and tools to study LD dynamics in vivo, and establish whether the zebrafish is a valid model to address how the brain communicates fat taste detection to intestinal enterocytes.

 描述（由申请人提供）：餐后循环中富含甘油三酯的脂蛋白（TRL）水平升高是心血管疾病的危险因素，餐后肠道产生的乳糜微粒对循环甘油三酯（TG）水平和产生有显着影响。主要取决于摄入和吸收的脂肪量。然而，越来越多的证据表明肠道可以主动调节餐后乳糜微粒的产生率。此外，代谢性的个体经常表现出高乳糜微粒血症，因此，肠道肠细胞吸收膳食脂肪酸并将其包装成通过乳糜微粒排出的甘油三酯。或储存在细胞质脂滴 (LD) 中，是由 TG 和胆固醇酯核心组成的亚细胞细胞器，周围有单层磷脂和多种蛋白质，包括周脂肪素在内的肠道 LD 是动态储存室；在高脂肪餐后数小时内，它们的数量和大小会增加，但如果没有再吃另一餐，则在 12-14 小时后几乎耗尽。在储存的 TG 耗尽之前，它会在乳糜微粒中迅速输出，这表明 LD 周转受到调节，尽管肠道 LD 调节对餐后血清 TG 水平有影响，但控制肠上皮细胞的机制。该提案的总体目标是阐明在急性高脂肪膳食和重新喂养后调节肠道 LD 的维持和周转的细胞机制。斑马鱼模型脊椎动物系统提供的体内成像机会将确定肠细胞中的 LD 是否会因重新进食而被中性脂肪酶快速脂解或被降解。在目标 2 中，将评估 LD 相关蛋白 perilipin-2 在调节肠道 LD 储存和周转中的作用，以评估与有利的脂蛋白谱相关的人类变体。确定它们是否会改变肠道 LD 动态，目标 3 将确定斑马鱼是否将脂肪视为一种味觉，以及这是否会导致足以引起鱼中 LD 分解和乳糜微粒释放的神经激活，正如所建议的那样。了解肠道对脂质储存和脂蛋白产生的调节对于制定预防和治疗高甘油三酯血症的策略至关重要。总的来说，所提出的实验将阐明调节肠道中脂质储存和周转的细胞机制，并产生新的方法。以及研究体内 LD 动力学的工具，并确定斑马鱼是否是解决大脑如何将脂肪味觉检测传递给肠细胞的有效模型。