Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest 1083, Hungary.
eNeuro. 2018 Jan 29;5(1). doi: 10.1523/ENEURO.0390-17.2018. eCollection 2018 Jan-Feb.
Mitochondrial function in neurons is tightly linked with metabolic and signaling mechanisms that ultimately determine neuronal performance. The subcellular distribution of these organelles is dynamically regulated as they are directed to axonal release sites on demand, but whether mitochondrial internal ultrastructure and molecular properties would reflect the actual performance requirements in a synapse-specific manner, remains to be established. Here, we examined performance-determining ultrastructural features of presynaptic mitochondria in GABAergic and glutamatergic axons of mice and human. Using electron-tomography and super-resolution microscopy we found, that these features were coupled to synaptic strength: mitochondria in boutons with high synaptic activity exhibited an ultrastructure optimized for high rate metabolism and contained higher levels of the respiratory chain protein cytochrome-c (CytC) than mitochondria in boutons with lower activity. The strong, cell type-independent correlation between mitochondrial ultrastructure, molecular fingerprints and synaptic performance suggests that changes in synaptic activity could trigger ultrastructural plasticity of presynaptic mitochondria, likely to adjust their performance to the actual metabolic demand.
神经元中的线粒体功能与代谢和信号机制紧密相连，这些机制最终决定了神经元的性能。这些细胞器的亚细胞分布是动态调节的，因为它们根据需要被引导到轴突释放部位，但线粒体内部超微结构和分子特性是否会以特定于突触的方式反映实际的性能要求，仍有待确定。在这里，我们检查了 GABA 能和谷氨酸能轴突中突触前线粒体的决定性能超微结构特征。使用电子断层扫描和超分辨率显微镜，我们发现这些特征与突触强度相关：在具有高突触活性的末梢中，线粒体表现出优化的高代谢率超微结构，并含有更高水平的呼吸链蛋白细胞色素 c（CytC），而在活性较低的末梢中，线粒体含有更低水平的 CytC。线粒体超微结构、分子指纹和突触性能之间的强烈、与细胞类型无关的相关性表明，突触活动的变化可能会引发突触前线粒体的超微结构可塑性，可能会调整其性能以适应实际的代谢需求。
