Role of ATGL in lipid droplet and nuclear lipidomes

非酒精性脂肪性肝病（NAFLD），由脂滴（LD）积聚定义，是一种普遍的疾病，涉及许多代谢性疾病的病因，包括肥胖、糖尿病和心血管疾病。尽管TAG代谢的重要性和我们对TAG合成途径的理解取得了进展，但调节肝脏TAG水解的机制及其对疾病病因的影响尚不清楚。本行政补充的目的是表征动态肝LD和核脂质体如何响应代谢刺激，如高脂肪喂养，atgl催化的脂肪分解和b -肾上腺素能信号。我们假设ATGL独特地改变LD和核脂质体，并且ATGL产生的特定脂质物种有助于Sirt1调节和细胞信号传导的下游作用。我们基于我们实验室的初步研究表明，ATGL诱导Sirt1活性控制PGC1- a/PPAR-a信号传导，介导b -肾上腺素能信号传导对Sirt1/PGC1- a/PPAR-a信号传导的影响，并以Sirt1依赖的方式诱导线粒体生物发生和脂肪酸氧化。这项研究的基本原理是确定LD和核脂质体的变化将极大地促进我们对这些细胞器及其脂质体在疾病病因学中的作用的理解，并可能有助于确定ATGL调节Sirt1的机制。该假设将通过两个特定目标进行验证：1)确定高脂肪喂养如何改变肝LD和核脂质组，以及ATGL在改变这些变化中的重要性；2)确定LD和核脂质组如何响应b -肾上腺素能信号变化，以及ATGL/脂解在介导这些影响中的作用。在第一个目标下，我们将对用对照组或ATGL shRNA喂食对照组或高脂饮食3个月的小鼠进行肝核和ld的脂质组学分析。第二个目的将表征b -肾上腺素能信号和慢性（shRNA）或急性（化学）抑制ATGL对原代小鼠肝细胞LD和核脂质体的影响。这些研究具有创新性，因为它们将利用脂质组学分析的强大技术平台来研究LD生物学和细胞器特异性脂质组学。这项工作意义重大，因为它将进一步加深我们对LD积累（即脂肪变性）、能量信号通路和NAFLD和2型糖尿病病因之间的联系的理解。

Non-alcoholic fatty liver disease (NAFLD), defined by lipid droplet (LD) accumulation, is a prevalent disorder that is involved in the etiology of numerous metabolic diseases including obesity, diabetes and cardiovascular disease. Despite the importance of TAG metabolism and the advancements into our understanding of the TAG synthetic pathway, the mechanisms regulating hepatic TAG hydrolysis and their effects on disease etiology are unknown. The objective of this administrative supplement is to characterize how the dynamic hepatic LD and nuclear lipidomes change in response to metabolic stimuli such as high fat feeding, ATGL-catalyzed lipolysis and B-adrenergic signaling. We hypothesis and ATGL uniquely alters LD and nuclear lipidomes and that specific lipid species generated by ATGL contribute to Sirt1 regulation and the downstream effects on cell signaling. We base this hypothesis on Preliminary Studies from our laboratory showing that ATGL induces Sirt1 activity to control PGC1-A/PPAR-a signaling, mediates the effects of B-adrenergic signaling on Sirt1/PGC1- a/PPAR-a signaling, and induces mitochondrial biogenesis and fatty acid oxidation in a Sirt1 dependent manner. The rationale for the proposed research is that identifying changes in LD and nuclear lipidomes will greatly advance our understanding of the contribution of these organelles and their lipidomes in disease etiology and may help identify the mechanism through which ATGL regulates Sirt1. The hypothesis will be tested using two specific aims: 1) to determine how high fat feeding alters the hepatic LD and nuclear lipidome and the importance of ATGL in altering these changes and 2) to determine how LD and nuclear lipidomes change in response to B-adrenergic signaling and the role of ATGL/lipolysis in mediating these effects. Under the first aim, we will perform lipidomic profiling of hepatic nuclei and LDs in mice treated with control or ATGL shRNA fed control or high fat diets for 3 months. The second aim will characterize the effects of B-adrenergic signaling and chronic (shRNA) or acute (chemical) inhibition of ATGL on the LD and nuclear lipidomes of primary mouse hepatocytes. These studies are innovative because they will employ the powerful technical platform of lipidomic profiling to the understudied area of LD biology and organelle-specific lipidomics. The proposes work is significant because it will further our understanding into the link between LD accumulation (i.e. steatosis), energy signaling pathways and the etiology of NAFLD and Type 2 Diabetes.