Mechanisms of cytoplasmic lipid droplet regulation in the intestine

肠道细胞质脂滴调节机制

• 批准号: 9244666
• 负责人: Meredith H Wilson
• 金额: $ 5.71万
• 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/9244666
• 关键词: 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; Optics; Oral; Organelles; Phospholipids; Population; Prevention; Prevention strategy; Production; Proteins; Regulation; Risk Factors; Role; Serum; Source; Surface; System; Taste Buds; Taste Perception; Testing; Transgenic Organisms; Triglycerides; Variant; Work; Zebrafish; absorption; base; cardiovascular risk factor; design; disorder risk; experimental study; feeding; in vivo; in vivo imaging; lipid metabolism; monolayer; novel; perilipin; protein expression; public health relevance; relating to nervous system; 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（由申请方提供）：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风险因素。饭后，肠道产生的乳糜微粒对循环甘油三酯（TG）水平有显著贡献，其产生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，肠道可以通过短暂的TG储存和延迟输出来积极调节餐后乳糜微粒的产生速率。此外，患有代谢综合征的个体通常表现出高乳糜微粒血症。因此，肠道TG储存和周转的失调可能会导致疾病风险。小肠上皮细胞吸收膳食脂肪酸并将其包装成TG，TG通过乳糜微粒输出或储存在细胞质脂滴（LD）中。LD是由TG和胆固醇酯的核心组成的亚细胞器，被单层磷脂和各种蛋白质（包括周脂）包围。肠道LD是动态的储存室;它们在高脂肪餐后的几个小时内数量和大小增加，但在没有另一餐的情况下，12-14小时后几乎耗尽。然而，如果在储存的TG耗尽之前食用后续膳食，则其迅速以乳糜微粒的形式输出，这表明LD周转受到调节。尽管肠LD调节餐后血清TG水平的影响，肠细胞LD调节的机制是很差的特点。该提案的总体目标是阐明调节急性高脂餐后和重新进食后肠道LD维持和转换的细胞机制。这些研究将利用斑马鱼模型脊椎动物系统提供的强大的转基因和体内成像机会。本提案的目的1将确定肠上皮细胞中的LD是否通过中性脂肪酶响应于再喂养而进行快速脂解或通过自噬介导的脂解降解。在目标2中，将探索LD相关蛋白perilipin-2在调节肠道LD储存和周转中的作用。将评价与有利的脂蛋白谱相关的perilipin-2的人类变体，以确定它们是否改变肠LD动力学。目标3将确定斑马鱼是否检测脂肪作为味觉，以及这是否导致神经激活足以引起鱼类中的LD分解和乳糜微粒释放，如人类研究所建议的那样。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脂血症的策略至关重要。总的来说，拟议的实验将阐明调节肠道中脂质储存和周转的细胞机制，产生新的方法和工具来研究体内LD动力学，并确定斑马鱼是否是一个有效的模型来解决大脑如何将脂肪味道检测传达给肠道肠细胞。