ALS-mutant SOD1-induced motor neuron apoptosis

描述(申请人提供)：肌萎缩侧索硬化症(ALS) 一种以上下运动丧失为特征的神经退行性疾病 神经元，在出现症状后1到6年内会导致死亡。 超氧化物歧化酶(SOD)的突变与2%-3%的病例有关 是肌萎缩侧索硬化症的唯一致病原因。我们发现这些 突变会削弱蛋白质的结构，从而降低与蛋白质的亲和力 锌。野生型和突变型缺锌超氧化物歧化酶均可诱导培养细胞凋亡 运动神经元通过一种需要一氧化氮的机制。然而，野生型和野生型 含铜和锌的突变型超氧化物歧化酶可抑制运动神经元的凋亡 由营养因子剥夺所致。这些结果表明，突变的超氧化物歧化酶 当蛋白质充满铜和铜时，它可以起到功能和保护作用 锌，但在锌原子丢失后会变得有毒。我们假设 使超氧化物歧化酶有毒的功能获得是由于锌的损失。我们进一步 散发性ALS患者野生型超氧化物歧化酶可能缺锌的假设 调节运动神经元的退化。我们的结果是有争议的，因为 与在转基因小鼠身上观察到的明显矛盾 ALS-突变型超氧化物歧化酶。我们建议在纯化的运动神经元中检验我们的假设。 高表达野生型人超氧化物歧化酶的转基因小鼠和小鼠 携带G93A和G37R ALS突变的超氧化物歧化酶。我们还将测试硝酸盐的作用 一氧化氮在营养因子剥夺诱导运动神经元凋亡中的作用 和锌缺乏的超氧化物歧化酶使用从小鼠的运动神经元“敲除”用于 神经型或内皮型一氧化氮合酶。这些研究的结果 调查将有助于解决有关该机制的一些争议。 肌萎缩侧索硬化症突变型超氧化物歧化酶毒性，将为运动机制提供新的见解 肌萎缩侧索硬化症神经元变性可能导致新的 治疗策略。

DESCRIPTION (provided by the Applicant): Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the loss of upper and lower motor neurons, which lead to death between 1 to 6 years after becoming symptomatic. Mutations in superoxide dismutase (SOD) are linked to 2-3 percent of the cases of ALS and are the only proven cause of the disease. We found that these mutations weaken the structure of the protein, which decreases the affinity for zinc. Both wild type and mutant zinc-deficient SOD induce apoptosis in cultured motor neurons by a mechanism requiring nitric oxide. However, both wild type and mutant copper and zinc-containing SOD prevent motor neuron apoptosis induced by trophic factor deprivation. These results suggest that mutant SOD protein can be functional and protective when it is replete with copper and zinc but becomes toxic after the zinc atom is lost. We hypothesize that the gain-of-function that makes SOD toxic is due to the loss of zinc. We further hypothesize that wild type SOD might become zinc-deficient in sporadic ALS mediating motor neuron degeneration. Our results are controversial since they are in apparent contradiction with observation in transgenic mice carrying ALS-mutant SOD. We propose to test our hypothesis in motor neurons purified from transgenic mice over expressing wild type human SOD as well as mice carrying the G93A and G37R ALS-mutant SOD. We also will test the role of nitric oxide in the induction of motor neuron apoptosis by trophic factor deprivation and Zn-deficient SOD by using motor neurons purified from mice "knockout" for neuronal or endothelial nitric oxide synthase. The results of these investigations will help to solve some controversy on the mechanism of ALS-mutant SOD toxicity and will provide new insight in the mechanism of motor neuron degeneration in ALS that could result in the development of new therapeutic strategies.