PEROXYNITRITE AND SOD IN MOTOR NEURON APOPTOSIS

描述(摘自申请者摘要)：我们的长期目标是 了解超氧化物歧化酶的突变如何增加氧化应激并导致 肌萎缩侧索硬化症(ALS)运动神经元死亡。我们已经展示了 扩散受限的过氧亚硝酸根的内源形成 超氧化物歧化和一氧化氮相互作用诱导培养的细胞凋亡 失去营养支持的胚胎大鼠运动神经元。这两种抑制剂都是 一氧化氮合成与铜锌超氧化物歧化酶(SOD)的传递 细胞内使用脂质体保护运动神经元免受细胞凋亡的影响。这些数据 提示一氧化氮和超氧化物之间的相互作用在 运动神经元的凋亡。超氧化物歧化酶的突变与选择性 肌萎缩侧索硬化症运动神经元变性及肌萎缩侧索硬化症-超氧化物歧化酶突变体的表达 转基因小鼠会导致运动神经元病。一种常见的表型在 目前研究的ALS-SOD突变是降低对锌的亲和力。我们 研究表明，缺乏锌的超氧化物歧化酶清除能力较差 超氧化物和更好的酪氨酸硝化催化剂。此外，铜 在缺锌的情况下，超氧化物歧化酶可以作为一种非特异性的单电子氧化酶，抢夺 来自抗坏血酸和谷胱甘肽等抗氧化剂的电子可以 转移到氧气中以产生超氧化物。在NO的存在下， 缺锌的超氧化物歧化酶能催化过氧亚硝酸根的形成。在上一次 在资金循环中，我们已经表明缺锌的SOD诱导细胞凋亡 运动神经元受一氧化氮依赖机制的影响。对于更新，我们的第一个 目的是进一步研究缺锌超氧化物歧化酶的机制。 杀死培养的运动神经元，并确定什么可以保护运动神经元 从这种毒性中。我们的第二个目标是描述一个或多个 用营养因子诱导运动神经元产生的超氧化物歧化来表征 营养因子诱导运动神经元超氧化物歧化的一个或多个来源 戒烟。我们的第三个目标是测试酪氨酸硝化的作用 过氧亚硝酸盐在任一种营养因子诱导的运动神经元死亡中的作用 缺乏锌或缺乏锌的超氧化物歧化酶。具体目标的完成将 为解释运动神经元是如何特别 易受超氧化物歧化酶突变的影响，并在散发性和家族性之间建立联系 臭气冲天。

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.