Department of Neurobiology, Interdisciplinary Center for Neurosciences, Heidelberg University , Heidelberg, Germany .
Antioxid Redox Signal. 2018 Oct 20;29(12):1109-1124. doi: 10.1089/ars.2017.7092. Epub 2017 Nov 14.
Excitotoxicity triggered by extrasynaptic N-methyl-d-aspartate-type glutamate receptors has been implicated in many neurodegenerative conditions, including Alzheimer's disease, Huntington's disease, amyotrophic lateral sclerosis, and stroke. Mitochondrial calcium overload leading to mitochondrial dysfunction represents an early event in excitotoxicity. Neurons are rendered resistant to excitotoxicity by previous periods of synaptic activity that activates a nuclear calcium-driven neuroprotective gene program. This process, termed acquired neuroprotection, involves transcriptional repression of the mitochondrial calcium uniporter leading to a reduction in excitotoxcity-associated mitochondrial calcium load. As mitochondrial calcium and the production of reactive oxygen species may be linked, we monitored excitotoxicity-associated changes in the mitochondrial redox status using the ratiometric glutathione redox potential indicator, glutaredoxin 1 (GRX1)-redox-sensitive green fluorescent protein (roGFP)2, targeted to the mitochondrial matrix. Aim of this study was to investigate if suppression of oxidative stress underlies mitoprotection afforded by synaptic activity.
We found that synaptic activity protects primary rat hippocampal neurons against acute excitotoxicity-induced mitochondrial oxidative stress and mitochondrial contraction associated with it. Downregulation of the mitochondrial uniporter by genetic means mimics the protective effect of synaptic activity on mitochondrial redox status. These findings indicate that oxidative stress acts downstream of mitochondrial calcium overload in excitotoxicity. Innovation and Conclusion: We established mito-GRX1-roGFP2 as a reliable and sensitive tool to monitor rapid redox changes in mitochondria during excitotoxicity. Our results highlight the importance of developing means of blocking mitochondrial calcium overload for therapeutic targeting of oxidative stress and mitochondrial dysfunction in neurodegenerative diseases. Antioxid. Redox. Signal. 29, 1109-1124.
由突触外 N-甲基-D-天冬氨酸型谷氨酸受体引发的兴奋性毒性与许多神经退行性疾病有关，包括阿尔茨海默病、亨廷顿病、肌萎缩侧索硬化症和中风。线粒体钙超载导致线粒体功能障碍是兴奋性毒性的早期事件。神经元通过先前的突触活动变得对兴奋性毒性具有抗性，这种活动激活了核钙驱动的神经保护基因程序。这个过程被称为获得性神经保护，涉及到线粒体钙单向转运体的转录抑制，导致与兴奋性毒性相关的线粒体钙负荷减少。由于线粒体钙和活性氧的产生可能有关联，我们使用比率型谷胱甘肽氧化还原电位指示剂（GRX1-氧化还原敏感的绿色荧光蛋白（roGFP）2）监测与线粒体氧化还原状态相关的兴奋性毒性变化，该指示剂靶向线粒体基质。本研究的目的是研究抑制氧化应激是否是突触活动提供的线粒体保护的基础。
我们发现，突触活动可保护原代大鼠海马神经元免受急性兴奋性毒性诱导的线粒体氧化应激和与之相关的线粒体收缩。通过遗传手段下调线粒体单向转运体可模拟突触活动对线粒体氧化还原状态的保护作用。这些发现表明，氧化应激在线粒体钙超载引起的兴奋性毒性中起下游作用。创新和结论：我们建立了 mito-GRX1-roGFP2，作为一种可靠和敏感的工具，用于监测兴奋性毒性过程中线粒体中快速的氧化还原变化。我们的结果强调了开发阻止线粒体钙超载的方法对于靶向神经退行性疾病中氧化应激和线粒体功能障碍的重要性。抗氧化还原信号。29, 1109-1124.
