Chi L, Ke Y, Luo C, Gozal D, Liu R
Department of Anatomy and Cell Biology, University of North Dakota School of Medicine, 501 North Columbia Road, Grand Forks, ND 58202, USA.
Neuroscience. 2007 Feb 9;144(3):991-1003. doi: 10.1016/j.neuroscience.2006.09.064. Epub 2006 Dec 5.
The mechanism of selective and age-dependent motor neuron degeneration in human amyotrophic lateral sclerosis (ALS) has not been defined and the role of glutathione (GSH) in association with motor neuron death remains largely unknown. A motor neuron-like cell culture system and a transgenic mouse model were used to study the effect of cellular GSH alteration on motor neuron cell death. Exposure of NSC34 motor neuron-like cells to ethacrynic acid (EA) or l-buthionine sulfoximine (BSO) dramatically reduced the cellular GSH levels, and was accompanied by increased production of reactive oxygen species (ROS) measured by the dichlorofluorescin (DCF) fluorescent oxidation assay. In addition, GSH depletion enhanced oxidative stress markers, AP-1 transcriptional activation, c-Jun, c-Fos and heme oxygenase-1 (HO-1) expression in NSC34 cells analyzed by a luciferase reporter, Western blotting and quantitative PCR assays respectively. Furthermore, depletion of GSH decreased mitochondrial function, facilitated apoptosis inducing factor (AIF) translocation, cytochrome c release, and caspase 3 activation, and consequently led to motor neuron-like cell apoptosis. In an ALS-like transgenic mouse model overexpressing mutant G93A-Cu, Zn-superoxide dismutase (SOD1) gene, we showed that the reduction of GSH in the spinal cord and motor neuron cells is correlated with AIF translocation, caspase 3 activation, and motor neuron degeneration during ALS-like disease onset and progression. Taken together, the in vitro and in vivo data presented in the current report demonstrated that decreased GSH promotes multiple apoptotic pathways contributing, at least partially, to motor neuron degeneration in ALS.
人类肌萎缩侧索硬化症（ALS）中选择性和年龄依赖性运动神经元变性的机制尚未明确，谷胱甘肽（GSH）与运动神经元死亡的关系在很大程度上仍不清楚。利用一种运动神经元样细胞培养系统和一种转基因小鼠模型来研究细胞内GSH改变对运动神经元细胞死亡的影响。将NSC34运动神经元样细胞暴露于依他尼酸（EA）或L-丁硫氨酸亚砜胺（BSO）中，可显著降低细胞内GSH水平，并伴随着通过二氯荧光素（DCF）荧光氧化测定法测得的活性氧（ROS）生成增加。此外，GSH耗竭分别通过荧光素酶报告基因、蛋白质免疫印迹和定量PCR分析增强了NSC34细胞中的氧化应激标志物、AP-1转录激活、c-Jun、c-Fos和血红素加氧酶-1（HO-1）的表达。此外，GSH耗竭降低了线粒体功能，促进了凋亡诱导因子（AIF）易位、细胞色素c释放和半胱天冬酶3激活，从而导致运动神经元样细胞凋亡。在一个过表达突变型G93A-铜锌超氧化物歧化酶（SOD1）基因的ALS样转基因小鼠模型中，我们发现脊髓和运动神经元细胞中GSH的减少与ALS样疾病发作和进展过程中的AIF易位、半胱天冬酶3激活以及运动神经元变性相关。综上所述，本报告中提供的体外和体内数据表明，GSH降低促进了多种凋亡途径，至少部分地导致了ALS中的运动神经元变性。
