Mechanism of Selective Toxicity of SOD1 Mutants in ALS

SOD1突变体对ALS的选择性毒性机制

• 批准号: 6370770
• 负责人: JOHN P CROW
• 金额: $ 35.88万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-06-15 至 2005-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6370770
• 关键词: SDS polyacrylamide gel electrophoresis; amyotrophic lateral sclerosis; atomic absorption spectrometry; chemical binding; colorimetry; electrochemistry; enzyme activity; genetically modified animals; high performance liquid chromatography; laboratory mouse; mass spectrometry; motor neurons; neurofilament; neurotoxins; peroxynitrites; posttranslational modifications; protein degradation; protein protein interaction; superoxide dismutase; western blottings; zinc

DESCRIPTION (provided by applicant): In 1993, it was first reported that a mutation to the gene coding for Cu,Zn superoxide dismutase (SOD1) was associated with a form of familial amyotrophic lateral sclerosis (ALS). Since that time, more than 70 single amino acid mutations to SOD1 have been found to cause ALS in humans. Mice transgenic for any one of several of the human SOD1 mutants develop progressive and ultimately lethal paralysis in a time-dependent manner reminiscent of human ALS. Studies in transgenic mice clearly indicate that SOD1 is toxic via a gained function because the mutant produces disease even in the presence of marked increases in total SOD1 enzyme activity. Despite the overwhelming evidence for a gained toxic function, the exact nature of that function has remained elusive. Equally puzzling has been the fact that SOD1 mutants are toxic only to motor neurons even though they are expressed in all cell types. Based on published results, in vitro characterizations of SOD1 mutants, studies in cultured motor neurons, and preliminary data from transgenic mice, we have formulated a hypothesis which may explain how all ALS-associated SOD1 mutations can be toxic via a common mechanism and why toxicity is manifested only in motor neurons. HYPOTHESIS: We are proposing that zinc-deficient (copper-containing) SOD1 is the common toxic phenotype of ALS-associated SOD1 mutants, that zinc-deficient SOD1 is injurious via its ability to utilize ascorbate, oxygen, and nitric oxide to catalyze the formation of the cytotoxin peroxynitrite, and that neurofilament proteins--which avidly bind zinc and are very abundant in motor neurons--contribute to the formation of zinc-deficient SOD1 preferentially in motor neurons. This study proposes: Specific Aim 1) to measure zinc-deficient SOD1 in the most widely used animal model of ALS (G93A transgenic mice) and determine the factors responsible for its accumulation, Specific Aim 2) to determine the conditions which lead to SOD1-mediated oxidant generation and its potential relationship to toxic protein aggregation, and Specific Aim 3) to evaluate the in vivo efficacy of two classes of compounds which protect cultured motor neurons from the toxic effects of zinc-deficient SOD1 and which enhance survival in G93A mice.

描述（由申请人提供）：1993年，首先报道了 编码CU的基因突变，Zn超氧化物歧化酶（SOD1）为 与一种家族性肌萎缩性侧索硬化症（ALS）相关。自从 那个时候，已经发现有70多个单一氨基酸突变为SOD1 在人类中造成ALS。小鼠转基因的几个人类SOD1中的任何一种 突变体在时间依赖的 让人联想到人类ALS的方式。对转基因小鼠的研究清楚地表明 该SOD1通过获得的功能是有毒的，因为突变体会产生疾病 即使存在明显增加的总SOD1酶活性。尽管 获得有毒功能的压倒性证据，其确切的性质 功能仍然难以捉摸。同样令人困惑的是SOD1 突变体对运动神经元有毒，即使它们在所有人中都表达 细胞类型。根据已发表的结果，SOD1的体外表征 突变体，培养运动神经元的研究以及来自的初步数据 转基因小鼠，我们提出了一个假设，可以解释所有人如何 与ALS相关的SOD1突变可以通过共同的机制有毒，以及为什么 毒性仅体现在运动神经元中。假设：我们提出 缺乏锌（含铜的）SOD1是常见的毒性表型 与ALS相关的SOD1突变体，缺乏锌的SOD1是有害的 能够利用抗坏血酸，氧气和一氧化氮来催化 细胞毒素过氧硝酸盐的形成和神经丝 蛋白质 - 这种蛋白质热量结合锌，并且在电机中非常丰富 神经元 - 与锌缺陷SOD1的形成优先在 运动神经元。这项研究提出：特定目的1）测量缺陷锌 ALS（G93A转基因小鼠）和最广泛使用的动物模型中的SOD1和 确定负责其积累的因素，具体目的2） 确定导致SOD1介导的氧化剂及其的条件 与有毒蛋白质聚集的潜在关系，并具体目的3） 评估两类保护的化合物的体内功效 缺乏锌的SOD1的毒性作用的培养的运动神经元，并且 增强G93A小鼠的生存率。