PEROXYNITRITE AND SOD IN MOTOR NEURON APOPTOSIS

描述（来自申请人的摘要）：我们的长期目标是 了解SOD突变如何增加氧化应激并导致 肌萎缩侧索硬化症（ALS）中运动神经元的死亡。我们已经表明 过氧化亚硝酸根的内源性形成是由扩散限制的 超氧阴离子与一氧化氮反应诱导细胞凋亡 缺乏营养支持的胚胎大鼠运动神经元。两种抑制剂 一氧化氮合成以及Cu、Zn超氧化物歧化酶（SOD）递送 细胞内脂质体保护运动神经元免于凋亡。这些数据 表明一氧化氮和超氧化物之间的相互作用在 运动神经元凋亡SOD的突变与选择性 ALS中运动神经元的变性和ALS-SOD突变体的表达 转基因小鼠产生运动神经元疾病。一种常见的表型， 目前研究的ALS-SOD突变是降低对锌的亲和力。我们 已经表明，缺锌的SOD在清除 超氧阴离子和酪氨酸硝化的较好催化剂。此外，铜 在缺锌时SOD可作为一种非特异性单电子氧化酶， 抗氧化剂如抗坏血酸和谷胱甘肽的电子， 转化为氧气产生超氧化物。在NO的存在下， 缺锌SOD可催化过氧亚硝酸根的形成。上一 我们已经证明，缺锌SOD诱导细胞凋亡， 运动神经元通过一氧化氮依赖机制。为了续约，我们的第一个 目的是进一步研究缺锌SOD的机制， 杀死培养的运动神经元，并确定什么可以保护运动神经元 这种毒性。我们的第二个目标是描述 在运动神经元中由营养因子诱导的超氧化物是表征 营养因子诱导运动神经元产生超氧化物源 戒断我们的第三个目的是通过以下方法测试酪氨酸硝化的作用： 过氧亚硝基阴离子在两种营养因子诱导的运动神经元死亡中的作用 或由缺锌SOD引起。具体目标的实现将 为解释运动神经元是如何特别 易受SOD突变的影响，并建立了散发性和家族性之间的联系。 特种部队

DESCRIPTION (From the Applicant's Abstract): Our long-term goal is to understand how mutations to SOD can increase oxidative stress and cause the death of motor neurons in amyotrophic lateral sclerosis (ALS). We have shown that endogenous formation of the peroxynitrite by the diffusion-limited reaction between superoxide and nitric oxide induces apoptosis in cultured embryonic rat motor neurons deprived of trophic support. Both inhibitors of nitric oxide synthesis as well as Cu, Zn superoxide dismutase (SOD) delivered intracellularly with liposomes protect motor neurons from apoptosis. These data indicate that the interaction between nitric oxide and superoxide has a role in motor neuron apoptosis. Mutations to SOD are implicated in the selective degeneration of motor neurons in ALS and expression of ALS-SOD mutants in transgenic mice produces motor neuron disease. A common phenotype among the ALS-SOD mutations so far investigated is to decrease the affinity for zinc. We have shown that zinc-deficient SOD is both less efficient at scavenging superoxide and a better catalyst of tyrosine nitration. Furthermore, the copper in zinc-deficient SOD can act as a non-specific one-electron oxidase, robbing electrons from antioxidants like ascorbate and glutathione that can be transferred to oxygen to produce superoxide. In the presence of NO, zinc-deficient SOD can catalyze the formation of peroxynitrite. In the previous cycle of funding, we have shown that zinc-deficient SOD induces apoptosis in motor neurons by a nitric oxide-dependent mechanism. For the renewal, our first aim is to further investigate the mechanisms by which zinc-deficient SODs can kill cultured motor neurons and to determine what can protect motor neurons from this toxicity. Our second aim is to characterize the source or sources of superoxide induced in motor neurons by trophic factor is to characterize the source or sources of superoxide induced in motor neurons by trophic factor withdrawal. Our third aim is to test the role of tyrosine nitration by peroxynitrite in the death of motor neurons induced by either trophic factor deprivation or by zinc-deficient SOD. Completion of the specific aims will provide a mechanistic basis for explaining how motor neurons are particularly vulnerable to SOD mutations and establish a link between sporadic and familial SODs.