Departamento de Biofísica, IB/UFRGS, Porto Alegre, RS, Brazil.
Arch Microbiol. 2010 Mar;192(3):221-8. doi: 10.1007/s00203-010-0551-2. Epub 2010 Feb 4.
Vitamin A (Vit A) is widely suggested to be protective against oxidative stress. However, different studies have been demonstrated the pro-oxidant effects of retinoids in several experimental models. In this work, we used the yeast Saccharomyces cerevisiae as a model organism to study the Vit A effects on superoxide dismutase (SOD)-deficient yeast strains. We report here that Vit A (10, 20 and 40 mg/ml) decreases the survival of exponentially growing yeast cells, especially in strains deficient in CuZnSOD (sod1Delta) and CuZnSOD/MnSOD (sod1Deltasod2Delta). We also observed the protective effect of vitamin E against the Vit A-induced toxicity. Possible adaptation effects induced by sub-lethal oxidative stress were monitored by pre-, co- and post-treatment with the oxidative agent paraquat. The enzymatic activities of catalase (CAT) and glutathione peroxidase (GPx), and the total glutathione content were determined after Vit A treatment. Our results showed that CuZnSOD represents an important defence against Vit A-generated oxidative damage. In SOD-deficient strains, the main defence against Vit A-produced reactive oxygen species (ROS) is GPx. However, the induction of GPx activity is not sufficient to prevent the Vit A-induced cell death in these mutants in exponential phase growth.
维生素 A（Vit A）被广泛认为具有抗氧化应激作用。然而，不同的研究已经在几种实验模型中证明了类视黄醇的促氧化剂作用。在这项工作中，我们使用酵母酿酒酵母作为模型生物来研究 Vit A 对超氧化物歧化酶（SOD）缺陷酵母菌株的影响。我们在这里报告 Vit A（10、20 和 40mg/ml）降低了指数生长期酵母细胞的存活率，特别是在 CuZnSOD（sod1Delta）和 CuZnSOD/MnSOD（sod1Deltasod2Delta）缺陷的菌株中。我们还观察到维生素 E 对 Vit A 诱导的毒性具有保护作用。通过用氧化剂百草枯进行预处理、共处理和后处理来监测亚致死氧化应激引起的可能的适应效应。在 Vit A 处理后测定了过氧化氢酶（CAT）和谷胱甘肽过氧化物酶（GPx）的酶活性和总谷胱甘肽含量。我们的结果表明，CuZnSOD 是对抗 Vit A 产生的氧化损伤的重要防御机制。在 SOD 缺陷菌株中，对 Vit A 产生的活性氧（ROS）的主要防御是 GPx。然而，在指数生长期生长的这些突变体中，GPx 活性的诱导不足以防止 Vit A 诱导的细胞死亡。
