Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague 14220, Czech Republic.
Laboratory of Biotransformation, Institute of Microbiology of the Czech Academy of Sciences, Vídeňská 1083, Prague 14220, Czech Republic.
Oxid Med Cell Longev. 2019 May 21;2019:1826303. doi: 10.1155/2019/1826303. eCollection 2019.
Pancreatic -cells are vulnerable to oxidative stress due to their low content of redox buffers, such as glutathione, but possess a rich content of thioredoxin, peroxiredoxin, and other proteins capable of redox relay, transferring redox signaling. Consequently, it may be predicted that cytosolic antioxidants could interfere with the cytosolic redox signaling and should not be recommended for any potential therapy. In contrast, mitochondrial matrix-targeted antioxidants could prevent the primary oxidative stress arising from the primary superoxide sources within the mitochondrial matrix, such as at the flavin (I) and ubiquinone (I) sites of superoxide formation within respiratory chain complex I and the outer ubiquinone site (III) of complex III. Therefore, using time-resolved confocal fluorescence monitoring with MitoSOX Red, we investigated various effects of mitochondria-targeted antioxidants in model pancreatic -cells (insulinoma INS-1E cells) and pancreatic islets. Both SkQ1 (a mitochondria-targeted plastoquinone) and a suppressor of complex III site Q electron leak (S3QEL) prevented superoxide production released to the mitochondrial matrix in INS-1E cells with stimulatory glucose, where SkQ1 also exhibited an antioxidant role for UCP2-silenced cells. SkQ1 acted similarly at nonstimulatory glucose but not in UCP2-silenced cells. Thus, UCP2 can facilitate the antioxidant mechanism based on SkQ1 fatty acid anion pairing. The elevated superoxide formation induced by antimycin was largely prevented by S3QEL, and that induced by rotenone was decreased by SkQ1 and S3QEL and slightly by S1QEL, acting at complex I site Q. Similar results were obtained with the MitoB probe, for the LC-MS-based assessment of the 4 hr accumulation of reactive oxygen species within the mitochondrial matrix but for isolated pancreatic islets. For 2 hr INS-1E incubations, some samples were influenced by the cell death during the experiment. Due to the frequent dependency of antioxidant effects on metabolic modes, we suggest a potential use of mitochondria-targeted antioxidants for the treatment of prediabetic states after cautious nutrition-controlled tests. Their targeted delivery might eventually attenuate the vicious spiral leading to type 2 diabetes.
胰腺细胞由于还原缓冲物（如谷胱甘肽）含量低，容易受到氧化应激的影响，但富含硫氧还蛋白、过氧化物酶和其他能够进行氧化还原传递的蛋白质，从而传递氧化还原信号。因此，可以预测细胞溶质抗氧化剂可能会干扰细胞溶质的氧化还原信号，不应该推荐用于任何潜在的治疗。相比之下，线粒体基质靶向抗氧化剂可以防止源自线粒体基质内初级超氧化物源的原发性氧化应激，例如在呼吸链复合物 I 的黄素（I）和泛醌（I）位点以及复合物 III 的外部泛醌（III）位点形成的初级超氧化物。因此，我们使用时间分辨共聚焦荧光监测用 MitoSOX Red 研究了线粒体靶向抗氧化剂在模型胰腺细胞（胰岛素瘤 INS-1E 细胞）和胰腺胰岛中的各种作用。SkQ1（一种线粒体靶向质体醌）和复合物 III 位点 Q 电子泄漏抑制剂（S3QEL）均能阻止刺激葡萄糖时 INS-1E 细胞释放到线粒体基质的超氧化物产生，SkQ1 对 UCP2 沉默细胞也表现出抗氧化作用。SkQ1 在非刺激葡萄糖时也有类似作用，但在 UCP2 沉默细胞中没有作用。因此，UCP2 可以促进基于 SkQ1 脂肪酸阴离子配对的抗氧化机制。S3QEL 大大阻止了抗霉素诱导的超氧化物形成，而 SkQ1 和 S3QEL 以及 S1QEL（作用于复合物 I 位点 Q）则降低了由鱼藤酮诱导的超氧化物形成。类似的结果也在用 MitoB 探针获得，用于基于 LC-MS 的线粒体基质中活性氧 4 小时积累的评估，但用于分离的胰腺胰岛。对于 2 小时的 INS-1E 孵育，一些样品受到实验过程中细胞死亡的影响。由于抗氧化剂作用经常依赖于代谢模式，我们建议在谨慎的营养控制测试后，将线粒体靶向抗氧化剂用于治疗糖尿病前期状态。它们的靶向递送最终可能会减弱导致 2 型糖尿病的恶性循环。
