Biophysical and genetic cues regulating lipid droplet packaging and alterations in obesity

调节脂滴包装和肥胖改变的生物物理和遗传线索

基本信息

批准号：
10456217
负责人：
Sayeepriyadarshini Anakk
金额：
$ 51.47万
依托单位：
UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-08-01 至 2024-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10456217
关键词：
Address Adipocytes Adipose tissue Adult Affect Behavior Bile Acid Biosynthesis Pathway Bile Acids Biogenesis Biological Models Biomechanics Biophysics Blood Vessels Brown Fat Calories Centers for Disease Control and Prevention (U.S.)Cryoelectron Microscopy Cues Data Development Diet Digestion Emulsions Endoplasmic Reticulum Epidemic Exposure to Extracellular Matrix Fat emulsion Fatty acid glycerol esters Gene Expression Genetic Genetic Transcription Goals Growth Impairment In Vitro Individual Knock-out Knockout Mice Knowledge Laser Scanning Confocal Microscopy Lipids Liquid substance Mechanics Membrane Metabolic syndrome Modeling Mus Nonesterified Fatty Acids Obesity Overnutrition Overweight Phase Physiological Pilot Projects Prevalence Process Property Regulation Risk Factors Roentgen Rays Role Signal Transduction Signaling Molecule Structure Testing Time Tissue Expansion Tissues Transcriptional Regulation Transgenic Organisms Triglycerides United States adiponectin design dietary epigenome experimental study gene synthesis genome-wide interdisciplinary approach lipid biosynthesis lipid metabolism mimetics novel nutrition obesity development obesogenic receptor response sterol ester sugar surfactant transcriptome unilamellar vesicle western diet

项目摘要

Summary Obesity is a major epidemic, which affects one in three individuals in the United States. Extensive remodeling of the adipose tissue and biogenesis of lipid droplets (LDs) occur in constant overnutrition to store the additional fat. The biophysical and genetic mechanisms controlling fat expansion are yet to be fully understood. Bile acids (BAs)—the body’s major natural surfactants— not only facilitate fat digestion but also act as signaling molecules to regulate fat metabolism by activating its receptors. Our preliminary data suggests that in response to BAs, LDs isolated from brown adipose tissue (BAT, containing small multilocular LDs) remain the same size whereas white (WAT, containing large unilocular LDs) adipose LDs integrate BAs in their core capturing TAGs that can rapidly shuttle from droplet to droplet. We will test the hypothesis that LD ripening, regulated by BA surfactants, is a dominant mechanism of LD growth instead of coalescence. We also found that fat is packed in layers in LDs. Additionally, we found that the extracellular matrix (ECM) of BAT is significantly more aligned that WAT’s ECM. We will investigate how the interplay between fat and ECM packing is altered in obesity. Finally, we developed a giant unilamellar vesicle (GUV) that mimics the endoplasmic reticulum LD biogenesis to tease these fat packaging differences. Our pilot experiments show that TAG distributes evenly in the GUV membrane before accumulating in a nascent TAG condensate. We will investigate a novel hypothesis for LD biogenesis that, in addition to membrane-tension, is controlled by liquid-liquid phase separation. We detected the presence of several BAs in adipose tissue and discovered that adipocyte-specific knockout of Farnesoid X Receptor (Fxr)—a BA receptor—resulted in a larger LD size and downregulated expression of genes controlling lipid metabolism. These surprising results indicate that LD remodeling may be transcriptionally regulated through the BA-Fxr axis. Further, we uncovered that a critical BA synthesis gene, Cyp27a1, was specifically induced upon adipogenesis and that its deletion of Cyp27a1 in preadipocytes impaired growth, indicating an important role of Cyp27a1 in adipogenesis. In addition to the focused approaches, we will also investigate the alterations in the transcriptome and epigenome of adipose remodeling during the development of obesity. Our exciting preliminary data underscores the importance of BAs' role (surfactant and signaling) in regulating LD size and expansion. This proposal will (1) determine how diet and BA regulation affect LD structure and biogenesis and (2) delineate the genetic mechanisms that regulate LD expansion during obesity. Overall, this project will uncover fundamental principles that govern LD dynamics in obesity.

概括肥胖是一种严重的流行病，影响着美国三分之一的人。脂肪组织的重塑和脂滴（LD）的生物发生不断发生营养过剩储存额外的脂肪控制脂肪的生物物理和遗传机制。胆汁酸（BA）——人体的主要天然表面活性剂——的扩展尚未完全了解。不仅能促进脂肪消化，还能作为信号分子调节脂肪代谢我们的初步数据表明，在响应 BA 时，分离出 LD。棕色脂肪组织（BAT，含有小多房 LD）保持相同大小，而白色（WAT，含有大的单眼 LD）脂肪 LD 将 BA 整合到其核心捕获中可以快速从一个液滴穿梭到另一个液滴的标签我们将测试 LD 成熟的假设。受 BA 表面活性剂调节，是 LD 生长而不是聚结的主要机制。还发现脂肪在 LD 中呈层状堆积。此外，我们还发现细胞外基质。 BAT 的 ECM 比 WAT 的 ECM 更加一致，我们将研究两者之间的相互作用。脂肪和 ECM 之间的堆积在肥胖中发生了改变。最后，我们开发出了一种巨大的单层结构。模仿内质网LD生物发生的囊泡（GUV）来梳理这些脂肪包装我们的中试实验表明，之前的 TAG 均匀分布在 GUV 膜中。我们将研究 LD 的新假设。除了膜张力之外，生物发生还受到液-液相分离的控制。我们检测到脂肪组织中存在多种 BA，并发现脂肪细胞特异性敲除 Farnesoid X 受体 (Fxr)（一种 BA 受体）会导致 LD 尺寸更大，并且这些令人惊讶的结果表明控制脂质代谢的基因表达下调。 LD 重塑可能通过 BA-Fxr 轴进行转录调节。发现关键的 BA 合成基因 Cyp27a1 是在脂肪生成及其前脂肪细胞中 Cyp27a1 的缺失损害了生长，表明 Cyp27a1 在脂肪生成中的重要作用除了重点方法之外，我们还将讨论。研究脂肪重塑过程中转录组和表观基因组的变化我们令人兴奋的初步数据强调了 BA 作用的重要性。（表面活性剂和信号传导）在调节 LD 大小和扩展方面的作用该提案将 (1) 确定。饮食和 BA 调节如何影响 LD 结构和生物发生，以及 (2) 描述遗传总体而言，该项目将揭示肥胖期间调节 LD 扩展的机制。控制肥胖 LD 动态的基本原则。