Localization and regulation of metabolic gene expression in response to dietary triglycerides

饮食甘油三酯代谢基因表达的定位和调节

• 批准号: 10156411
• 负责人: Michelle Biederman
• 金额: $ 4.6万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-02-01 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10156411
• 关键词: Address; Animal Model; Animals; Apolipoproteins; Apolipoproteins B; Behavioral; Biological Assay; Cardiovascular Diseases; Cell Nucleus; Cell physiology; Cells; Cholesterol; Chylomicrons; Complex; Confocal Microscopy; Cultured Cells; Data; Dependence; Development; Diabetes Mellitus; Dietary Fats; Dietary Fatty Acid; Dietary Practices; Engineering; Enterocytes; Fatty Liver; Fatty acid glycerol esters; Fluorescence; Future; Gene Expression; Genes; Genetic; Genetic Transcription; Heart Diseases; High Fat Diet; Homeostasis; Human; Hydrophobicity; Individual; Inflammation; Insulin; Intestines; Knowledge; Larva; Lead; Link; Lipids; Lipoproteins; Liver; Location; Low-Density Lipoproteins; Measurement; Measures; Mediating; Membrane; Metabolic; Metabolic Diseases; Metabolic Pathway; Metabolism; Mus; Nutrient; Nutritional; Obesity; Optical reporter; Optics; Organ; Pathway interactions; Pharmacology; Phospholipids; Plasma; Production; Proteins; Regulation; Reporter; Research; Satiation; Signal Transduction; Site; Small Intestines; System; Techniques; Testing; Time; Tissues; Transgenic Organisms; Triglycerides; Very low density lipoprotein; Work; Zebrafish; absorption; apolipoprotein A-IV; body system; cell type; design; dietary; experimental study; feeding; gastrointestinal system; genomic locus; lipid metabolism; lipid transfer protein; microbial; microbiota; microsomal triglyceride transfer protein; mutant; overexpression; particle; response; screening; single-cell RNA sequencing; small molecule; spatiotemporal; tool; transcription factor; uptake

Abstract: The metabolic response to meals high in fat and cholesterol requires the coordination of a complex system of cellular processes. Disruption of these cellular processes can lead to metabolic diseases, such as diabetes, heart disease, and hepatic steatosis. Previous experiments have shown that high-fat diets increase transcription of genes and gene pathways that mediate lipid metabolism, storage, and secretion. One of the most highly upregulated genes within the digestive organs (liver and small intestine), in response to dietary triglycerides (TG), is apolipoprotein A4 (apoa4). The function of ApoA4 protein is currently unknown, but it has been implicated in the regulation of lipoprotein particle synthesis and secretion, as well as satiety, inflammation, and insulin responsivity. Since TG-induced apoa4 gene expression has not been observed in cultured cells and only observed in whole animal models, I will use the zebrafish system to examine the spatial and temporal expression of lipid metabolic genes in response to dietary TG. The digestive system of zebrafish is functionally and developmentally similar to mammalian systems, with high genetic conservation in essential metabolic components. Because larval zebrafish are optically clear and genetically tractable, I have engineered a cell- tracing, fluorescent reporter in the endogenous apoa4 locus, which will allow me to visualize the dietary TG response in live zebrafish larvae. I plan to characterize the timing and location of apoa4 expression to determine whether expression of lipid metabolic genes is a cell-autonomous response to direct, cellular uptake of TGs; or if it is driven by short- and/or long-distance intercellular signaling. The proposed apoa4 reporter will also allow me to screen for the effect of specific pathway genes and transcription factors (TFs) on the TG-induced transcriptional response of intestinal enterocytes that results in apoa4 expression. I plan to use my apoa4 reporter as a measure of dietary TG absorption to help delineate the cellular mechanisms that underlie the dietary TG metabolic gene response. Although, several TFs implicated in regulating apoa4 have been identified in the liver, TFs responsible for regulating apoa4 in enterocytes have not been characterized. We know that lipoprotein synthesis and secretion in digestive organs is largely dependent on microsomal triglyceride transfer protein (MTP) activity, but the mechanisms underlying the dependence on MTP for apoa4 gene expression in different digestive organs is unknown. To determine the regulatory mechanisms underlying MTP-dependence in the intestine, I plan to use the apoa4 transgenic reporter to assay genes that potentially mediate the relationships between dietary TG absorption, MTP activity, and apoa4 expression. The proposed research will identify regulatory relationships between the metabolic gene response to dietary TGs, and lipoprotein production and secretion. Additionally, the proposed apoa4 optical reporter will be a valuable tool for rapid measurement of triglyceride absorption in response to changes in nutritional, behavioral, microbial, pharmacological, and environmental conditions in future studies.

摘要：对高脂肪和高胆固醇饮食的代谢反应需要一种复合体的协调 细胞过程系统。这些细胞过程的中断会导致代谢性疾病，例如 糖尿病、心脏病和肝脏脂肪变性。此前的实验表明，高脂肪饮食会增加 调节脂肪代谢、储存和分泌的基因和基因途径的转录。其中一个 消化器官(肝脏和小肠)中表达最高的基因，对饮食的反应 甘油三酯(TG)是载脂蛋白A4(Apoa4)。ApoA4蛋白的功能目前尚不清楚，但它已经 参与调节脂蛋白颗粒的合成和分泌，以及饱腹感、炎症、 和胰岛素的响应性。由于TG诱导的apoa4基因在培养细胞中未见表达， 只在整个动物模型中观察，我将使用斑马鱼系统来检查空间和时间 脂肪代谢基因的表达对膳食甘油三酯的响应。斑马鱼的消化系统在功能上 在发育上与哺乳动物系统相似，在必要的代谢中具有高度的遗传保守性 组件。因为斑马鱼的幼体在视觉上是透明的，而且遗传上容易驯服，所以我设计了一个细胞-- 在内源性载脂蛋白4基因座上的示踪荧光报告，这将使我能够可视化饮食中的甘油三酯 活斑马鱼幼体的反应。我计划鉴定apoa4表达的时间和位置，以确定 脂代谢基因的表达是否是对细胞直接摄取TGS的细胞自主反应；或者 如果它是由短和/或长距离的细胞间信号驱动的。 建议的apoa4记者还将允许我筛选特定途径基因和 转录因子(TF)对TG诱导的肠上皮细胞转录反应的影响 载脂蛋白4的表达。我计划用我的apoa4记者作为衡量饮食中甘油三酯吸收的指标，以帮助描绘 膳食甘油三酯代谢基因反应的细胞机制。尽管，有几个TF牵涉到 调节载脂蛋白4在肝脏中已被发现，而负责调节肠细胞中载脂蛋白4的转录因子尚未发现。 被刻画出来了。我们知道，消化器官中脂蛋白的合成和分泌在很大程度上依赖于 对微粒体甘油三酯转移蛋白(MTP)活性的影响，但依赖于 Apoa4基因在不同消化器官中表达的MTP尚不清楚。要确定监管机构 肠道中MTP依赖的潜在机制，我计划使用apoa4转基因报告来检测 可能调节膳食甘油三酯吸收、MTP活性和载脂蛋白4关系的基因 表情。这项拟议的研究将确定代谢基因反应之间的调节关系 对膳食TGS，以及脂蛋白的产生和分泌的影响。此外，拟议的apoa4光学记录器将 是一种有价值的工具，用于快速测量甘油三酯的吸收以响应营养变化， 未来研究中的行为、微生物、药理和环境条件。