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 (EtOH) consumption, subsequent abstinence from EtOH, or fasting differentially affect LD membrane proteome content, and that these changes influence how LDs interacts with other intracellular organelles. Here, male Wistar rats were pair-fed liquid control or EtOH diets for 6 weeks, then randomly-chosen animals from both groups were refed either a control diet for 7 days or were fasted for 48 hr before sacrifice. From all groups, LD membrane proteins from purified liver LDs were analyzed immunochemically and by mass spectrometry-proteomics. Liver LD numbers and sizes were greater in EtOH-fed rats than in pair-fed control, 7 day refed or fasted rats. Compared with control rats, EtOH feeding markedly altered the LD membrane proteome, enriching LD structural perilipins and proteins involved in lipid biosynthesis, while lowering LD lipase levels. EtOH feeding also lowered LD-associated mitochondrial and lysosomal proteins. In seven day refed (i.e. EtOH-abstained) or fasted-EtOH-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 EtOH-induced steatosis, its resolution after withdrawal and abstinence, and changes in LD interactions with other intracellular organelles.

中文翻译：

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脂滴膜蛋白质组重塑与乙醇诱导的肝脂肪变性及其解决类似。


脂滴 (LD) 由封闭在磷脂单层中的中性脂质组成，其中含有调节 LD 功能的膜相关蛋白。尽管 LD 在脂质代谢中发挥着至关重要的作用，但在脂肪变性等疾病背景下 LD 蛋白组成的重塑仍然知之甚少。我们假设长期乙醇 (EtOH) 消耗、随后戒除 EtOH 或禁食对 LD 膜蛋白质组含量有不同影响，并且这些变化影响 LD 与其他细胞内细胞器的相互作用。在这里，雄性 Wistar 大鼠被配对喂养液体对照或乙醇饮食 6 周，然后从两组中随机选择的动物被喂食对照饮食 7 天或在处死前禁食 48 小时。对所有组中纯化的肝脏 LD 中的 LD 膜蛋白进行免疫化学分析和质谱-蛋白质组学分析。 EtOH 喂养的大鼠的肝脏 LD 数量和大小大于配对喂养的对照、7 天再喂养或禁食的大鼠。与对照大鼠相比，乙醇喂养显着改变了 LD 膜蛋白质组，丰富了 LD 结构周脂质和参与脂质生物合成的蛋白质，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 天禁食（即禁食 EtOH）或禁食 EtOH 喂养的大鼠中，我们检测到 LD 蛋白质组的明显重塑，这是通过脂质生物合成蛋白水平较低以及 LD 与线粒体和溶酶体相互作用增强来判断的。我们的研究揭示了 LD 膜蛋白质组显着重塑的证据，该蛋白质组调节 EtOH 诱导的脂肪变性、戒断和禁欲后的消退，以及 LD 与其他细胞内细胞器相互作用的变化。