Nobel C I, Kimland M, Lind B, Orrenius S, Slater A F
Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
J Biol Chem. 1995 Nov 3;270(44):26202-8. doi: 10.1074/jbc.270.44.26202.
Dithiocarbamates are metal-chelating compounds that can exert either pro-oxidant or antioxidant effects in different situations. They have recently been found to potently inhibit apoptotic cell death, an activity attributed to their antioxidant action. However, when thymocytes were exposed to pyrrolidine dithiocarbamate, an oxidation of the glutathione pool occurred within 90 min. Longer incubation resulted in cell shrinkage, chromatin fragmentation, glutathione depletion, and eventual cell lysis, which is typical of apoptosis in these cells. These changes were inhibited by inclusion of non-permeable metal chelators in the incubation medium, suggesting that pyrrolidine dithiocarbamate exerts its toxic effect by transporting a redox-active metal into the cell. This was directly confirmed when sustained 8-fold elevations of intracellular copper were detected after addition of pyrrolidine dithiocarbamate. In agreement with this, supplementation of the incubation medium with submicromolar concentrations of copper significantly potentiated pyrrolidine dithiocarbamate toxicity. We conclude that pyrrolidine dithiocarbamate exerts a powerful pro-oxidant effect on thymocytes due to its ability to transport external redox-active copper into cells. The resulting increase in glutathione disulfide may also explain the temporary anti-apoptotic activity of this compound described in other systems.
二硫代氨基甲酸盐是金属螯合化合物，在不同情况下可发挥促氧化或抗氧化作用。最近发现它们能有效抑制凋亡性细胞死亡，这种活性归因于其抗氧化作用。然而，当胸腺细胞暴露于吡咯烷二硫代氨基甲酸盐时，90分钟内谷胱甘肽池就会发生氧化。延长孵育时间会导致细胞皱缩、染色质碎片化、谷胱甘肽耗竭，最终细胞裂解，这是这些细胞凋亡的典型特征。在孵育培养基中加入不可渗透的金属螯合剂可抑制这些变化，这表明吡咯烷二硫代氨基甲酸盐通过将具有氧化还原活性的金属转运到细胞内发挥其毒性作用。加入吡咯烷二硫代氨基甲酸盐后，当检测到细胞内铜持续升高8倍时，这一点得到了直接证实。与此一致的是，在孵育培养基中补充亚微摩尔浓度的铜可显著增强吡咯烷二硫代氨基甲酸盐的毒性。我们得出结论，吡咯烷二硫代氨基甲酸盐对胸腺细胞发挥强大的促氧化作用，这是由于其能够将外部具有氧化还原活性的铜转运到细胞内。由此导致的谷胱甘肽二硫化物增加也可能解释了该化合物在其他系统中描述的暂时抗凋亡活性。
