Muyderman Håkan, Wadey Alison L, Nilsson Michael, Sims Neil R
Centre for Neuroscience and Department of Medical Biochemistry, School of Medicine, Flinders University, Adelaide, Australia.
J Neurochem. 2007 Aug;102(4):1369-82. doi: 10.1111/j.1471-4159.2007.04641.x. Epub 2007 May 4.
The major cellular antioxidant, glutathione, is mostly localized in the cytosol but a small portion is found in mitochondria. We have recently shown that highly selective depletion of mitochondrial glutathione in astrocytes in culture markedly increased cell death induced by the peroxynitrite donor, 3-morpholino-syndnonimine. The present study was aimed at characterizing the increase in susceptibility arising from mitochondrial glutathione loss and testing the possibility that elevating this metabolite pool above normal values could be protective. The increased vulnerability of astrocytes with depleted mitochondrial glutathione to Sin-1 was confirmed. Furthermore, these cells showed marked increases in sensitivity to hydrogen peroxide and also to high concentrations of the nitric oxide donor, S-nitroso-N-acetyl-penicillamine. The increase in cell death was mostly due to necrosis as indicated by substantially increased release of lactate dehydrogenase and staining of nuclei with propidium iodide but little change in annexin V staining and caspase 3 activation. The enhanced cell loss was blocked by prior restoration of the mitochondrial glutathione content. It was also essentially fully inhibited by treatment with cyclosporin A, consistent with a role for the mitochondrial permeability transition in the development of cell death. Susceptibility to the classical apoptosis inducer, staurosporine, was only affected to a small extent in contrast to the response to the other substances tested. Incubation of normal astrocytes with glutathione monoethylester produced large and long-lasting increases in mitochondrial glutathione content with much smaller effects on the cytosolic glutathione pool. This treatment reduced cell death on exposure to 3-morpholino-syndnonimine or hydrogen peroxide but not S-nitroso-N-acetyl-pencillamine or staurosporine. These findings provide evidence for an important role for mitochondrial glutathione in preserving cell viability during periods of oxidative or nitrative stress and indicate that increases in this glutathione pool can confer protection against some of these stressors.
主要的细胞抗氧化剂谷胱甘肽大多定位于胞质溶胶中，但有一小部分存在于线粒体中。我们最近发现，培养的星形胶质细胞中线粒体谷胱甘肽的高度选择性耗竭显著增加了过氧亚硝酸盐供体3-吗啉代-辛二亚胺诱导的细胞死亡。本研究旨在表征线粒体谷胱甘肽缺失导致的易感性增加，并测试将这种代谢物池提升至正常水平以上是否具有保护作用。线粒体谷胱甘肽耗竭的星形胶质细胞对Sin-1的易感性增加得到了证实。此外，这些细胞对过氧化氢以及高浓度的一氧化氮供体S-亚硝基-N-乙酰青霉胺的敏感性显著增加。细胞死亡的增加主要是由于坏死，这表现为乳酸脱氢酶的释放大幅增加以及细胞核被碘化丙啶染色，但膜联蛋白V染色和半胱天冬酶3激活变化不大。线粒体谷胱甘肽含量的预先恢复可阻止细胞损失的增加。用环孢素A处理也基本完全抑制了细胞损失，这与线粒体通透性转换在细胞死亡发展中的作用一致。与对其他测试物质的反应相比，对经典凋亡诱导剂星形孢菌素的易感性仅受到轻微影响。用谷胱甘肽单乙酯孵育正常星形胶质细胞会使线粒体谷胱甘肽含量大幅且持久增加，而对胞质谷胱甘肽池的影响要小得多。这种处理减少了暴露于3-吗啉代-辛二亚胺或过氧化氢时的细胞死亡，但对S-亚硝基-N-乙酰青霉胺或星形孢菌素无效。这些发现为线粒体谷胱甘肽在氧化或硝化应激期间维持细胞活力方面的重要作用提供了证据，并表明该谷胱甘肽池的增加可赋予针对某些应激源的保护作用。
