Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089, USA.
Biochem J. 2010 Apr 28;428(1):85-93. doi: 10.1042/BJ20100164.
Excessive generation of nitric oxide radical (NO*) in neuroinflammation, excitotoxicity and during age-related neurodegenerative disorders entails the localized and concerted increase in nitric oxide synthase(s) expression in glial cells and neurons. The aim of the present study was to assess the biological significance of the impact of NO* on the cell's thiol status with emphasis on S-glutathionylation of targeted proteins. Exposure of primary cortical neurons or astrocytes to increasing flow rates of NO* (0.061-0.25 microM/s) resulted in the following. (i) A decrease in GSH (glutathione) in neurons accompanied by formation of GSNO (S-nitrosoglutathione) and GSSG (glutathione disulfide); neurons were far more sensitive to NO* exposure than astrocytes. (ii) A dose-dependent oxidation of the cellular redox status: the neuron's redox potential increased approximately 42 mV and that of astrocytes approximately 23 mV. A good correlation was observed between cell viability and the cellular redox potential. The higher susceptibility of neurons to NO* can be partly explained by a reduced capacity to recover GSH through lower activities of GSNO and GSSG reductases. (iii) S-glutathionylation of a small subset of proteins, among them GAPDH (glyceraldehyde-3-phosphate dehydrogenase), the S-glutathionylation of which resulted in inhibition of enzyme activity. The quantitative analyses of changes in the cell's thiol potential upon NO* exposure and their consequences for S-glutathionylation are discussed in terms of the distinct redox environment of astrocytes and neurons.
在神经炎症、兴奋毒性和与年龄相关的神经退行性疾病中，一氧化氮自由基（NO*）的过度产生需要胶质细胞和神经元中一氧化氮合酶（NOS）表达的局部协同增加。本研究旨在评估 NO对细胞硫醇状态的影响的生物学意义，重点是靶向蛋白的 S-谷胱甘肽化。将原代皮质神经元或星形胶质细胞暴露于递增的 NO流速（0.061-0.25 microM/s）会导致以下结果。（i）神经元中 GSH（谷胱甘肽）减少，同时形成 GSNO（S-亚硝基谷胱甘肽）和 GSSG（谷胱甘肽二硫化物）；神经元对 NO暴露比星形胶质细胞更为敏感。（ii）细胞氧化还原状态的剂量依赖性氧化：神经元的氧化还原电位增加约 42 mV，星形胶质细胞的氧化还原电位增加约 23 mV。细胞活力与细胞氧化还原电位之间存在良好的相关性。神经元对 NO的更高敏感性可以部分解释为通过降低 GSNO 和 GSSG 还原酶的活性来恢复 GSH 的能力降低。（iii）一小部分蛋白质的 S-谷胱甘肽化，其中包括 GAPDH（甘油醛-3-磷酸脱氢酶），其 S-谷胱甘肽化导致酶活性抑制。NO*暴露后细胞硫醇状态的定量分析及其对 S-谷胱甘肽化的影响，根据星形胶质细胞和神经元的不同氧化还原环境进行了讨论。
