Shin Sang Mi, Cho Il Je, Kim Sang Geon
Innovative Drug Research Center for Metabolic and Inflammatory Diseases, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742, Korea.
Mol Pharmacol. 2009 Oct;76(4):884-95. doi: 10.1124/mol.109.058479. Epub 2009 Jul 20.
Arachidonic acid (AA, a proinflammatory fatty acid) in combination with iron promotes excess reactive oxygen species (ROS) production and exerts a deleterious effect on mitochondria. We have shown previously that activation of AMP-activated protein kinase (AMPK) protects hepatocytes from AA + iron-induced apoptosis. Resveratrol, a polyphenol in grapes, has beneficial effects mediated through SIRT1, LKB1, and AMPK. This study investigated the potential of resveratrol to protect against the mitochondrial impairment induced by AA + iron and the underlying mechanism for this cytoprotection. Resveratrol treatment inhibited apoptosis, ROS production, and glutathione depletion elicited by AA + iron in HepG2 cells. In addition, resveratrol attenuated superoxide generation in mitochondria and inhibited mitochondrial dysfunction induced by AA + iron. Overall, AMPK activation by resveratrol contributed to cell survival, as supported by the reversal of its restoration of mitochondrial membrane potential by either overexpression of a dominant-negative mutant of AMPKalpha or compound C treatment. Resveratrol increased inhibitory phosphorylation of glycogen synthase kinase-3beta (GSK3beta) downstream of AMPK, which contributed to mitochondrial protection and cell survival. Likewise, small interfering RNA knockdown of LKB1, an upstream kinase of AMPK, reduced the ability of resveratrol to protect cells from mitochondrial dysfunction. Furthermore, this LKB1-dependent mitochondrial protection resulted from resveratrol's poly(ADP-ribose)polymerase activation, but not SIRT1 activation, as supported by the experiment using 3-aminobenzamide, a poly(ADP-ribose)polymerase inhibitor. Other polyphenols, such as apigenin, genistein, and daidzein, did not activate AMPK or protect mitochondria against AA + iron. Thus, resveratrol protects cells from AA + iron-induced ROS production and mitochondrial dysfunction through AMPK-mediated inhibitory phosphorylation of GSK3beta downstream of poly(ADP-ribose)polymerase-LKB1 pathway.
花生四烯酸（AA，一种促炎脂肪酸）与铁结合会促进过量活性氧（ROS）的产生，并对线粒体产生有害影响。我们之前已经表明，AMP激活的蛋白激酶（AMPK）的激活可保护肝细胞免受AA+铁诱导的凋亡。白藜芦醇是葡萄中的一种多酚，通过SIRT1、LKB1和AMPK介导发挥有益作用。本研究调查了白藜芦醇预防AA+铁诱导的线粒体损伤的潜力及其细胞保护的潜在机制。白藜芦醇处理可抑制HepG2细胞中由AA+铁引发的凋亡、ROS产生和谷胱甘肽耗竭。此外，白藜芦醇可减轻线粒体中超氧化物的产生，并抑制AA+铁诱导的线粒体功能障碍。总体而言，白藜芦醇激活AMPK有助于细胞存活，这得到了通过过表达AMPKα显性负突变体或化合物C处理来逆转其线粒体膜电位恢复实验结果的支持。白藜芦醇增加了AMPK下游糖原合酶激酶-3β（GSK3β）的抑制性磷酸化水平，这有助于线粒体保护和细胞存活。同样，AMPK的上游激酶LKB1通过小干扰RNA敲低后降低了白藜芦醇保护细胞免受线粒体功能障碍影响的能力。此外，这种依赖LKB1的线粒体保护作用是由白藜芦醇激活聚（ADP-核糖）聚合酶所致，而非SIRT1激活，使用聚（ADP-核糖）聚合酶抑制剂3-氨基苯甲酰胺的实验结果支持了这一点。其他多酚，如芹菜素、染料木黄酮和大豆苷元，不会激活AMPK或保护线粒体免受AA+铁的影响。因此，白藜芦醇通过聚（ADP-核糖）聚合酶-LKB1途径下游的AMPK介导的GSK3β抑制性磷酸化作用，保护细胞免受AA+铁诱导的ROS产生和线粒体功能障碍。
