PDF(Pubmed)
Abstract：
Acetyl-CoA carboxylase 2 plays a crucial role in regulating mitochondrial fatty acid oxidation in cardiomyocytes. Lithium, a monovalent cation known for its cardioprotective potential, has been investigated for its influence on mitochondrial bioenergetics. The present study explored whether lithium modulated acetyl-CoA carboxylase 2 and mitochondrial fatty acid metabolism in cardiomyocytes and the potential therapeutic applications of lithium in alleviating metabolic stress. Mitochondrial bioenergetic function, fatty acid oxidation, reactive oxygen species production, membrane potential and the expression of proteins involved in fatty acid metabolism in H9c2 cardiomyocytes treated with LiCl for 48 h was measured by using a Seahorse extracellular flux analyzer, fluorescence microscopy and western blotting. Small interfering RNA against glucose transporter type 4 was transfected into H9c2 cardiomyocytes for 48 h to induce metabolic stress mimicking insulin resistance. The results revealed that LiCl at a concentration of 0.3 mM (but not at a concentration of 0.1 or 1.0 mM) upregulated the expression of phosphorylated (p-)glycogen synthase kinase-3 beta and downregulated the expression of p-acetyl-CoA carboxylase 2 but did not affect the expression of adenosine monophosphate-activated protein kinase or calcineurin. Cotreatment with TWS119 (8 µM) and LiCl (0.3 mM) downregulated p-acetyl-CoA carboxylase 2 expression to a similar extent as did treatment with TWS119 (8 µM) alone. Moreover, LiCl (0.3 mM) inhibited mitochondrial fatty acid oxidation, improved coupling efficiency and the cellular respiratory control ratio, hindered reactive oxygen species production and proton leakage and restored mitochondrial membrane potential in glucose transporter type 4 knockdown-H9c2 cardiomyocytes. These findings suggested that low therapeutic levels of lithium can downregulate p-acetyl-CoA carboxylase 2, thus reducing mitochondrial fatty acid oxidation and oxidative stress in cardiomyocytes.
摘要：
乙酰辅酶A羧化酶2在调节心肌细胞线粒体脂肪酸氧化中起关键作用。锂，以其心脏保护潜力而闻名的一价阳离子，已经研究了它对线粒体生物能学的影响。本研究探讨了锂是否调节了心肌细胞中乙酰辅酶A羧化酶2和线粒体脂肪酸的代谢，以及锂在减轻代谢应激方面的潜在治疗应用。线粒体生物能量功能，脂肪酸氧化，活性氧的产生，使用Seahorse细胞外通量分析仪测量用LiCl处理48小时的H9c2心肌细胞的膜电位和参与脂肪酸代谢的蛋白质的表达，荧光显微镜和蛋白质印迹。将针对4型葡萄糖转运蛋白的小干扰RNA转染到H9c2心肌细胞中48小时以诱导模拟胰岛素抵抗的代谢应激。结果表明，浓度为0.3mM（但浓度为0.1或1.0mM）的LiCl上调了磷酸化（p-）糖原合酶激酶3β的表达，下调了对乙酰辅酶A羧化酶2的表达，但不影响腺苷一磷酸活化的蛋白激酶或钙调磷酸酶的表达。用TWS119（8µM）和LiCl（0.3mM）协同处理下调对乙酰辅酶A羧化酶2的表达，与单独用TWS119（8µM）处理的程度相似。此外，LiCl（0.3mM）抑制线粒体脂肪酸氧化，提高了耦合效率和细胞呼吸控制率，4型葡萄糖转运蛋白敲低H9c2心肌细胞中活性氧的产生和质子泄漏以及线粒体膜电位的恢复。这些发现表明，低治疗水平的锂可以下调对乙酰辅酶A羧化酶2，从而减少心肌细胞中的线粒体脂肪酸氧化和氧化应激。
