Gelain Daniel Pens, de Bittencourt Pasquali Matheus Augusto, Zanotto-Filho Alfeu, de Souza Luiz Fernando, de Oliveira Ramatis Birnfeld, Klamt Fábio, Moreira José Cláudio Fonseca
Centro de Estudos em Estresse Oxidativo, Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Chem Biol Interact. 2008 Jul 10;174(1):38-43. doi: 10.1016/j.cbi.2008.04.025. Epub 2008 May 2.
Vitamin A (retinol) is widely used as an antioxidant in therapeutic interventions and dietary supplementations. However, the redox properties of retinoids have been the subject of intense debate in the last few years, as recent works observed deleterious effects caused by retinol supplementation in clinical trials. In the present work, we show that retinol treatment (7 microM, 24 h) led to catalase (EC 1.11.1.6; CAT) activation in cultured Sertoli cells by increasing its protein content in a reactive species-dependent manner. Retinol treatment also increased cell lipoperoxidation, assessed by determination of thiobarbituric acid-reactive substances (TBARS), and intracellular reactive species production, determined by the real-time dihydrochlorofluorescein (DCFH-DA) assay. However, no alterations on CAT mRNA expression (assessed by RT-PCR) were observed, indicating an effect independent of CAT gene-transcription regulation. Importantly, all the effects induced by retinol were inhibited by the antioxidant Trolox, a hydrophilic analogue of alpha-tocopherol. These results show for the first time that retinol increases CAT activity by a redox-dependent modulation of its protein content in a cell culture model. CAT activity or expression are widely used as indexes of oxidative stress in biological systems; since no changes in CAT mRNA expression were detected in these conditions, the use of CAT gene-transcription activation when assessing oxidative stress should be re-evaluated.
维生素A（视黄醇）在治疗干预和膳食补充中被广泛用作抗氧化剂。然而，在过去几年中，类视黄醇的氧化还原特性一直是激烈争论的主题，因为最近的研究在临床试验中观察到视黄醇补充剂会产生有害影响。在本研究中，我们发现视黄醇处理（7 microM，24小时）通过以活性物质依赖性方式增加其蛋白质含量，导致培养的支持细胞中的过氧化氢酶（EC 1.11.1.6；CAT）活化。视黄醇处理还增加了细胞脂质过氧化（通过测定硫代巴比妥酸反应性物质（TBARS）评估）和细胞内活性物质的产生（通过实时二氯荧光素（DCFH-DA）测定）。然而，未观察到CAT mRNA表达的变化（通过RT-PCR评估），表明该效应独立于CAT基因转录调控。重要的是，视黄醇诱导的所有效应均被抗氧化剂Trolox（α-生育酚的亲水性类似物）抑制。这些结果首次表明，在细胞培养模型中，视黄醇通过对其蛋白质含量的氧化还原依赖性调节来增加CAT活性。CAT活性或表达被广泛用作生物系统中氧化应激的指标；由于在这些条件下未检测到CAT mRNA表达的变化，因此在评估氧化应激时对CAT基因转录激活的使用应重新评估。
