Madeja Zbigniew, Sroka Jolanta, Nyström Christina, Björkhem-Bergman Linda, Nordman Tomas, Damdimopoulos Anastasios, Nalvarte Ivan, Eriksson Lennart C, Spyrou Giannis, Olsson Jerker M, Björnstedt Mikael
Department of Laboratory Medicine, Division of Pathology, F46, Karolinska Institutet, Karolinska University Hospital in Huddinge, SE-141 86 Stockholm, Sweden.
Biochem Pharmacol. 2005 Jun 15;69(12):1765-72. doi: 10.1016/j.bcp.2005.02.023.
The selenoprotein thioredoxin reductase is a key enzyme in selenium metabolism, reducing selenium compounds and thereby providing selenide to synthesis of all selenoproteins. We evaluated the importance of active TrxR1 in selenium-induced cytotoxicity using transfected TrxR1 over-expressing stable Human Embryo Kidney (HEK-293) cells and modulation of activity by pretreatment with low concentration of selenite. Treatment with sodium selenite induced cytotoxity in a dose-dependent manner in both TrxR1 over-expressing and control cells. However, TrxR1 over-expressing cells, which were preincubated for 72h with 0.1 microM selenite, were significantly more resistant to selenite cytotoxicity than control cells. To demonstrate the early effects of selenite on behaviour of HEK-293 cells, we also investigated the influence of this compound on cell motility. We observed inhibition of cell motility by 50 microM selenite immediately after administration. Moreover, TrxR1 over-expressing cells preincubated with a low concentration of selenite were more resistant to the inhibitory effect of 50 microM selenite than those not preincubated. It was also observed that the TrxR over-expressing cells showed higher TrxR1 activity than control cells and the preincubation of over-expressing cells with 0.1 microM selenite induced further significant increase in the activity of TrxR1. On the other hand, we demonstrated that TrxR1 over-expressing cells showed decreased glutathione peroxidase activity compared to control cells. These data strongly suggest that TrxR1 may be a crucial enzyme responsible for cell resistance against selenium cytotoxicity.
硒蛋白硫氧还蛋白还原酶是硒代谢中的关键酶，它可还原硒化合物，从而为所有硒蛋白的合成提供硒化物。我们使用转染了硫氧还蛋白还原酶1（TrxR1）过表达稳定的人胚肾（HEK - 293）细胞，并通过低浓度亚硒酸盐预处理来调节其活性，以此评估活性TrxR1在硒诱导的细胞毒性中的重要性。亚硒酸钠处理在TrxR1过表达细胞和对照细胞中均以剂量依赖性方式诱导细胞毒性。然而，用0.1微摩尔亚硒酸盐预孵育72小时的TrxR1过表达细胞比对照细胞对亚硒酸盐细胞毒性的抗性明显更强。为了证明亚硒酸盐对HEK - 293细胞行为的早期影响，我们还研究了该化合物对细胞运动的影响。给药后立即观察到50微摩尔亚硒酸盐对细胞运动有抑制作用。此外，用低浓度亚硒酸盐预孵育的TrxR1过表达细胞比未预孵育的细胞对50微摩尔亚硒酸盐的抑制作用更具抗性。还观察到TrxR过表达细胞的TrxR1活性高于对照细胞，并且用0.1微摩尔亚硒酸盐预孵育过表达细胞会导致TrxR1活性进一步显著增加。另一方面，我们证明TrxR1过表达细胞与对照细胞相比，谷胱甘肽过氧化物酶活性降低。这些数据强烈表明，TrxR1可能是负责细胞抵抗硒细胞毒性作用的关键酶。
