PEROXYNITRITE AND SOD IN MOTOR NEURON APOPTOSIS

说明（申请人摘要）：过氧亚硝酸盐是一种强氧化剂 在不同的细胞类型中引发凋亡。 申请人已经表明 过氧亚硝酸盐是由扩散限制反应产生的， 超氧阴离子和一氧化氮诱导胚胎大鼠细胞凋亡 失去了萎缩的支持的运动神经元。 这两种一氧化氮抑制剂 合成和递送野生型Cu/Zn超氧化物歧化酶（SOD） 细胞内脂质体保护营养因子剥夺的运动神经元 从细胞凋亡。 超氧化物歧化酶的突变与 ALS运动神经元选择性变性及SOD突变体的表达 与ALS相关的细胞凋亡诱导培养物中的神经元凋亡。 申请人 以前曾提出，SOD突变体的主要功能是由 通过过氧亚硝酸盐增加酪氨酸硝化的催化作用。 SOD能 催化酪氨酸和蛋白质被过氧亚硝酸根硝化， 3-硝基酪氨酸 硝化可以破坏酪氨酸激酶信号 转导和结构蛋白的组装。 酪氨酸硝化 发生在ALS和其他神经退行性疾病中， 疾病、多发性硬化症和阿尔茨海默病。 常见表型 在迄今为止研究的所有ALS/SOD突变中， 锌。 锌缺乏的SOD清除超氧化物的效率较低， 也是酪氨酸硝化的较好催化剂。 本 申请人假设在应激下的运动神经元 增加一氧化氮和超氧化物的产生速率， 使得这些神经元特别容易受到缺锌SOD的影响。 的 申请人提出研究神经元一氧化氮的诱导 营养缺乏对培养的大鼠胚胎运动神经元合成酶的影响 并描述运动神经元中超氧化物的来源。 使用 高效pH敏感脂质体递送具有限定金属含量的SOD 对于运动神经元，申请人将研究缺锌SOD的作用 在运动神经元中启动凋亡以及一氧化氮是否 ALS突变体SOD的毒性所必需的。 完成具体的 目的将有助于解释为什么运动神经元特别容易受到 与ALS相关的SOD突变。

DESCRIPTION (Applicant's Abstract): Peroxynitrite is a powerful oxidant that initiates apoptosis in diverse cell types. The applicant has shown that peroxynitrite produced by the diffusion-limited reaction between superoxide and nitric oxide induces apoptosis in cultured embryonic rat motor neuron deprived of atrophic support. Both inhibitors of nitric oxide synthesis and wild type Cu/Zn superoxide dismutase (SOD) delivered intracellularly with liposomes protect trophic factor deprived motor neurons from apoptosis. Mutations to superoxide dismutase are implicated in the selective degeneration of motor neurons in ALS and expression of SOD mutants associated with ALS induces neuronal apoptosis in cultures. The applicant has previously suggested that the main function of SOD mutants results from increased catalysis of tyrosine nitration by peroxynitrite. SOD can catalyze nitration of tyrosine and protein by peroxynitrite to form 3-nitrotyrosine. Nitration can disrupt both tyrosine kinase signal transduction and the assembly of structural proteins. Tyrosine nitration occurs in ALS and other neurodegenerative disorders including Parkinson's Disease, multiple sclerosis and Alzheimer's Disease. The common phenotype among all ALS/SOD mutations so far investigated is a decreased affinity for zinc. Zinc deficient SOD is both less efficient at scavenging superoxide and is also a better catalyst of tyrosine nitration. In the present application the applicant hypothesizes that motor neurons under stress increase the rates of both nitric oxide and superoxide production which makes these neurons particularly vulnerable to zinc-deficient SOD. The applicant proposes to investigate the induction of neuronal nitric oxide synthase in cultured rat embryonic motor neurons deprived of trophic support and characterize the sources of superoxide in motor neurons. Using efficient pH sensitive liposomes to deliver SOD with defined metal contents to motor neurons, the applicant will examine the role of zinc-deficient SOD in initiating apoptosis in motor neurons and whether nitric oxide is necessary for the toxicity of ALS mutant SOD. Completion of the specific aims will help explain why motor neurons are particularly vulnerable to mutations in SOD associated with ALS.