LANEH, Department of Zoology, School of Life Sciences, East China Normal University, Shanghai, China.
Department of Aquaculture Technology, School of Aquatic Sciences and Fisheries Technology, University of Dar es Salaam, Dar es Salaam, Tanzania.
J Nutr Biochem. 2024 Sep;131:109678. doi: 10.1016/j.jnutbio.2024.109678. Epub 2024 Jun 5.
The solute carrier family 25 member 1 (Slc25a1)-dependent mitochondrial citrate shuttle is responsible for exporting citrate from the mitochondria to the cytoplasm for supporting lipid biosynthesis and protein acetylation. Previous studies on Slc25a1 concentrated on pathological models. However, the importance of Slc25a1 in maintaining metabolic homeostasis under normal nutritional conditions remains poorly understood. Here, we investigated the mechanism of mitochondrial citrate shuttle in maintaining lipid metabolism homeostasis in male Nile tilapia (Oreochromis niloticus). To achieve the objective, we blocked the mitochondrial citrate shuttle by inhibiting Slc25a1 under normal nutritional conditions. Slc25a1 inhibition was established by feeding Nile tilapia with 250 mg/kg 1,2,3-benzenetricarboxylic acid hydrate for 6 weeks or intraperitoneal injecting them with dsRNA to knockdown slc25a1b for 7 days. The Nile tilapia with Slc25a1 inhibition exhibited an obesity-like phenotype accompanied by fat deposition, liver damage and hyperglycemia. Moreover, Slc25a1 inhibition decreased hepatic citrate-derived acetyl-CoA, but increased hepatic triglyceride levels. Furthermore, Slc25a1 inhibition replenished cytoplasmic acetyl-CoA through enhanced acetate pathway, which led to hepatic triglycerides accumulation. However, acetate-derived acetyl-CoA caused by hepatic Slc25a1 inhibition did not activate de novo lipogenesis, but rather modified protein acetylation. In addition, hepatic Slc25a1 inhibition enhanced fatty acids esterification through acetate-derived acetyl-CoA, which increased Lipin1 acetylation and its protein stability. Collectively, our results illustrate that inhibiting mitochondrial citrate shuttle triggers lipid anabolic remodeling and results in lipid accumulation, indicating the importance of mitochondrial citrate shuttle in maintaining lipid metabolism homeostasis.
溶质载体家族 25 成员 1(Slc25a1)依赖性线粒体柠檬酸穿梭负责将柠檬酸从线粒体输出到细胞质,以支持脂质生物合成和蛋白质乙酰化。以前关于 Slc25a1 的研究集中在病理模型上。然而,Slc25a1 在正常营养条件下维持代谢平衡的重要性仍知之甚少。在这里,我们研究了线粒体柠檬酸穿梭在维持雄性尼罗罗非鱼(Oreochromis niloticus)脂质代谢平衡中的机制。为了实现这一目标,我们在正常营养条件下通过抑制 Slc25a1 来阻断线粒体柠檬酸穿梭。通过用 250mg/kg 1,2,3-苯三甲酸水合物喂养尼罗罗非鱼 6 周或用 dsRNA 腹腔注射它们来敲低 slc25a1b 7 天来建立 Slc25a1 抑制。Slc25a1 抑制的尼罗罗非鱼表现出肥胖样表型,伴有脂肪沉积、肝损伤和高血糖。此外,Slc25a1 抑制降低了肝柠檬酸衍生的乙酰辅酶 A,但增加了肝甘油三酯水平。此外,Slc25a1 抑制通过增强乙酸途径补充细胞质乙酰辅酶 A,导致肝甘油三酯积累。然而,由肝 Slc25a1 抑制引起的乙酸衍生的乙酰辅酶 A没有激活从头合成脂肪生成,而是修饰了蛋白质乙酰化。此外,肝 Slc25a1 抑制通过乙酸衍生的乙酰辅酶 A增强脂肪酸酯化,增加 Lipin1 乙酰化及其蛋白质稳定性。总之,我们的结果表明,抑制线粒体柠檬酸穿梭会引发脂质合成代谢重塑,导致脂质积累,这表明线粒体柠檬酸穿梭在维持脂质代谢平衡中的重要性。
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