VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, USA; Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA; Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.
VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, USA; Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA.
J Lipid Res. 2021;62:100049. doi: 10.1016/j.jlr.2021.100049. Epub 2021 Feb 20.
Lipid droplets (LDs) are composed of neutral lipids enclosed in a phospholipid monolayer, which harbors membrane-associated proteins that regulate LD functions. Despite the crucial role of LDs in lipid metabolism, remodeling of LD protein composition in disease contexts, such as steatosis, remains poorly understood. We hypothesized that chronic ethanol consumption, subsequent abstinence from ethanol, or fasting differentially affects the LD membrane proteome content and that these changes influence how LDs interact with other intracellular organelles. Here, male Wistar rats were pair-fed liquid control or ethanol diets for 6 weeks, and then, randomly chosen animals from both groups were either refed a control diet for 7 days or fasted for 48 h before euthanizing. From all groups, LD membrane proteins from purified liver LDs were analyzed immunochemically and by MS proteomics. Liver LD numbers and sizes were greater in ethanol-fed rats than in pair-fed control, 7-day refed, or fasted rats. Compared with control rats, ethanol feeding markedly altered the LD membrane proteome, enriching LD structural perilipins and proteins involved in lipid biosynthesis, while lowering LD lipase levels. Ethanol feeding also lowered LD-associated mitochondrial and lysosomal proteins. In 7-day refed (i.e., ethanol-abstained) or fasted-ethanol-fed rats, we detected distinct remodeling of the LD proteome, as judged by lower levels of lipid biosynthetic proteins, and enhanced LD interaction with mitochondria and lysosomes. Our study reveals evidence of significant remodeling of the LD membrane proteome that regulates ethanol-induced steatosis, its resolution after withdrawal and abstinence, and changes in LD interactions with other intracellular organelles.
脂滴（LDs）由包裹在磷脂单层中的中性脂质组成，含有调节 LD 功能的膜相关蛋白。尽管 LDs 在脂质代谢中起着至关重要的作用，但在疾病情况下，如脂肪变性，LD 蛋白组成的重塑仍知之甚少。我们假设慢性乙醇消耗、随后的乙醇戒断或禁食会以不同的方式影响 LD 膜蛋白质组的含量，这些变化会影响 LD 与其他细胞内细胞器的相互作用。在这里，雄性 Wistar 大鼠被喂食液体对照或乙醇饮食 6 周，然后从两组中随机选择动物，要么再喂食对照饮食 7 天，要么禁食 48 小时后处死。从所有组中，从纯化的肝 LD 中分离 LD 膜蛋白，通过免疫化学和 MS 蛋白质组学进行分析。与配对喂养的对照组、7 天再喂养组或禁食组相比，乙醇喂养的大鼠肝 LD 数量和大小更大。与对照组相比，乙醇喂养显著改变了 LD 膜蛋白质组，丰富了 LD 结构蛋白 perilipin 和参与脂质生物合成的蛋白，同时降低了 LD 脂肪酶水平。乙醇喂养还降低了 LD 相关的线粒体和溶酶体蛋白。在 7 天再喂养（即乙醇戒断）或禁食-乙醇喂养的大鼠中，我们检测到 LD 蛋白质组的明显重塑，这可以从脂质生物合成蛋白水平降低和 LD 与线粒体和溶酶体的相互作用增强来判断。我们的研究揭示了 LD 膜蛋白质组的显著重塑的证据，这调节了乙醇诱导的脂肪变性、戒断和 abstinence 后的消退，以及 LD 与其他细胞内细胞器的相互作用的变化。
