Depletion of Mitochondrial S-Nitrosothiols in ALS

描述（由申请人提供）：越来越多的证据表明线粒体功能障碍有助于肌萎缩侧索硬化症（ALS）的发病机制。 然而，ALS中线粒体功能障碍的原因尚不清楚。 我们推测，家族性ALS相关的SOD 1突变体异常耗尽S-亚硝基硫醇（SNOs）在线粒体中导致线粒体变性和运动神经元死亡。 S-亚硝基硫醇是具有连接至半胱氨酸残基的NO基团的肽和蛋白质。 肽SNO是有效的抗氧化剂和神经保护剂。 蛋白质上的关键半胱氨酸残基的S-亚硝基化正成为信号转导调节的一种机制。 因此，线粒体SNO的异常消耗可能是SOD 1突变体的毒性功能获得。 这是一个新的可验证的工作假设，在ALS领域几乎未探索的领域。 为了支持我们的假设，我们的初步数据表明，肽和蛋白质SNO主要位于表达野生型SOD 1的细胞系的线粒体中。 此外，在表达SOD 1突变体的细胞的线粒体中，SNO水平显著降低。 在具体目标1的拟议研究中，我们将扩大我们的初步研究在细胞系中的体内动物模型，并确定是否线粒体SNO水平降低突变SOD 1转基因小鼠的脊髓之前或在肌肉无力的发作时。 在具体目标2中，我们将确定线粒体SNO水平的恢复是否改善线粒体功能和表达突变体SOD 1的细胞的活力。 如果我们证实了我们的假设，那么在未来的研究中，我们将确定SNO供体化合物是否改善突变SOD 1转基因小鼠的存活率。 我们的长期目标是确定SNO供体化合物（已用于治疗冠状动脉疾病数十年，毒性有限）是否对ALS患者具有治疗效果。

DESCRIPTION (provided by applicant): There is increasing evidence that mitochondrial dysfunction contributes to amyotrophic lateral sclerosis (ALS) pathogenesis. However the causes of mitochondrial dysfunction in ALS are not known. We hypothesize that familial ALS-associated SOD1 mutants aberrantly deplete S-nitrosothiols (SNOs) in mitochondria leading to mitochondrial degeneration and motor neuron death. S-nitrosothiols are peptides and proteins that have an NO group attached to a cysteine residue. Peptide SNOs are potent antioxidants and neuroprotective. S-nitrosylation of critical cysteine residues on proteins is emerging as a mechanism of signal transduction regulation. Therefore aberrant depletion of mitochondrial SNOs is likely to be a toxic gain-of-function of SOD1 mutants. This is a novel testable working hypothesis in a virtually unexplored area in the ALS field. In support of our hypothesis, our preliminary data indicate that peptide and protein SNOs are located primarily in the mitochondria of cell lines expressing wild-type SOD1. Moreover, SNO levels are significantly decreased in the mitochondria of cells expressing SOD1 mutants. In specific aim 1 of the proposed studies we will extend our preliminary studies in cell lines to an in vivo animal model and determine if mitochondrial SNO levels are decreased in the spinal cord of mutant SOD1 transgenic mice before or at the time of onset of muscle weakness. In specific aim 2 we will determine if restoration of mitochondrial SNO levels improves mitochondrial function and the viability of cells expressing mutant SOD1. If we confirm our hypothesis, then in future studies we will determine if SNO donor compounds improve the survival of mutant SOD1 transgenic mice. Our long term goal is to determine if SNO donor compounds (which have been used for decades in the treatment of coronary artery disease with limited toxicity) have therapeutic efficacy in patients with ALS.