Sirianni Ana C, Jiang Jiying, Zeng Jiang, Mao Lilly L, Zhou Shuanhu, Sugarbaker Peter, Zhang Xinmu, Li Wei, Friedlander Robert M, Wang Xin
Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Department of Anatomy, Weifang Medical University, Weifang, Shandong, China.
J Neurochem. 2015 Sep;134(5):956-68. doi: 10.1111/jnc.13190. Epub 2015 Jul 14.
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive motor neuron loss. Evidence suggests that mitochondrial dysfunction, apoptosis, oxidative stress, inflammation, glutamate excitotoxicity, and proteasomal dysfunction are all responsible for ALS pathogenesis. N-acetyl-tryptophan has been identified as an inhibitor of mitochondrial cytochrome c release and therefore is a potential neuroprotective agent. By quantifying cell death, we demonstrate that N-acetyl-l-tryptophan (L-NAT) and N-acetyl-DL-tryptophan are neuroprotective in NSC-34 motor neuron-like cells and/or primary motor neurons, while their isomer N-acetyl-d-tryptophan has no protective effect. These findings are consistent with energy minimization and molecular modeling analysis, confirming that L-NAT generates the most stable complex with the neurokinin-1 receptor (NK-1R). L-NAT inhibits the secretion of Substance P and IL-1β (Enzyme-Linked Immunosorbent Assay and/or dot blots) and mitochondrial dysfunction by effectively inhibiting the release of cytochrome c/Smac/AIF from mitochondria into the cytoplasm and activation of apoptotic pathways, including the activation of caspase-1, -9, and -3, as well as proteasomal dysfunction through restoring chymotrypsin-like, trypsin-like, and caspase-like proteasome activity. These data provide insight into the molecular mechanisms by which L-NAT offers neuroprotection in models of ALS and suggest its potential as a novel therapeutic strategy for ALS. We demonstrate that L-NAT (N-acetyl-l-tryptophan), but not D-NAT, rescues NSC-34 cells and primary motor neurons from cell death. L-NAT inhibits the secretion of Substance P and IL-1β, and caspase-1 activation, the release of cytochrome c/Smac/AIF, and the activation of caspase -9, and -3, as well as proteasomal dysfunction. The data suggest the potential of L-NAT as a novel therapeutic strategy for amyotrophic lateral sclerosis (ALS). AIF, apoptosis-inducing factor.
肌萎缩侧索硬化症（ALS）是一种以进行性运动神经元丧失为特征的神经退行性疾病。有证据表明，线粒体功能障碍、细胞凋亡、氧化应激、炎症、谷氨酸兴奋性毒性和蛋白酶体功能障碍均与ALS的发病机制有关。N-乙酰色氨酸已被确定为线粒体细胞色素c释放的抑制剂，因此是一种潜在的神经保护剂。通过量化细胞死亡，我们证明N-乙酰-L-色氨酸（L-NAT）和N-乙酰-DL-色氨酸在NSC-34运动神经元样细胞和/或原代运动神经元中具有神经保护作用，而它们的异构体N-乙酰-D-色氨酸则没有保护作用。这些发现与能量最小化和分子模型分析一致，证实L-NAT与神经激肽-1受体（NK-1R）形成最稳定的复合物。L-NAT通过有效抑制细胞色素c/Smac/AIF从线粒体释放到细胞质中以及激活凋亡途径，包括激活半胱天冬酶-1、-9和-3，从而抑制P物质和IL-1β的分泌（酶联免疫吸附测定和/或斑点印迹）以及线粒体功能障碍，同时通过恢复类胰凝乳蛋白酶、类胰蛋白酶和类半胱天冬酶蛋白酶体活性来抑制蛋白酶体功能障碍。这些数据为L-NAT在ALS模型中提供神经保护的分子机制提供了见解，并表明其作为ALS新型治疗策略的潜力。我们证明L-NAT（N-乙酰-L-色氨酸）而非D-NAT可使NSC-34细胞和原代运动神经元免于细胞死亡。L-NAT抑制P物质和IL-1β的分泌、半胱天冬酶-1的激活、细胞色素c/Smac/AIF的释放以及半胱天冬酶-9和-3的激活，以及蛋白酶体功能障碍。这些数据表明L-NAT作为肌萎缩侧索硬化症（ALS）新型治疗策略的潜力。AIF，凋亡诱导因子。
