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: 10406152
• 负责人: Michelle Biederman
• 金额: $ 4.68万
• 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/10406152
• 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膳食的代谢反应需要复杂的协调 细胞过程系统。这些细胞过程的破坏可能导致代谢疾病，例如 糖尿病、心脏病和肝脂肪变性。先前的实验表明，高脂肪饮食会增加 介导脂质代谢、储存和分泌的基因和基因途径的转录。中的一个 消化器官（肝脏和小肠）内最高度上调的基因，以响应饮食 甘油三酯（TG），是载脂蛋白A4（apoa4）。 ApoA4蛋白的功能目前尚不清楚，但它具有 参与脂蛋白颗粒合成和分泌的调节，以及饱腹感、炎症、 和胰岛素反应性。由于在培养细胞中尚未观察到 TG 诱导的 apoa4 基因表达， 仅在整个动物模型中观察到，我将使用斑马鱼系统来检查空间和时间 脂质代谢基因响应膳食TG的表达。斑马鱼的消化系统功能正常 并且在发育上与哺乳动物系统相似，在基本代谢方面具有高度遗传保守性 成分。因为斑马鱼幼虫光学透明且基因易于处理，所以我设计了一种细胞- 追踪内源性 apoa4 位点的荧光报告基因，这将使我能够可视化膳食 TG 活斑马鱼幼虫的反应。我计划表征 apoa4 表达的时间和位置以确定 脂质代谢基因的表达是否是对直接细胞摄取 TG 的细胞自主反应；或者 如果它是由短距离和/或长距离细胞间信号传导驱动的。 拟议的 apoa4 报告基因还可以让我筛选特定途径基因的作用和 转录因子 (TF) 对 TG 诱导的肠上皮细胞转录反应的影响 apoa4 表达。我计划使用我的 apoa4 报告基因作为膳食 TG 吸收的衡量标准，以帮助描绘 饮食TG代谢基因反应的细胞机制。尽管有多个 TF 牵涉其中 已在肝脏中鉴定出调节 apoa4 的 TF，但尚未在肠细胞中鉴定出负责调节 apoa4 的 TF 被表征。我们知道，消化器官中脂蛋白的合成和分泌很大程度上取决于 微粒体甘油三酯转移蛋白（MTP）活性，但其依赖的机制 不同消化器官中 apoa4 基因表达的 MTP 尚不清楚。以确定监管 肠道中 MTP 依赖性的机制，我计划使用 apoa4 转基因报告基因来检测 可能介导膳食 TG 吸收、MTP 活性和 apoa4 之间关系的基因 表达。拟议的研究将确定代谢基因反应之间的调节关系 膳食甘油三酯以及脂蛋白的产生和分泌。此外，拟议的 apoa4 光学报告基因将 是快速测量甘油三酯吸收以响应营养变化的有价值的工具， 未来研究中的行为、微生物、药理学和环境条件。