Regulation of mitochondrial dynamics and distribution by synapse position and neuronal activity in the axon
Regulation of mitochondrial dynamics and distribution by synapse position and neuronal activity in the axon
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DOI：
10.1111/ejn.12263
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发表时间：
2013-08-01
影响因子：
3.4
通讯作者：
Okabe, Shigeo
中科院分区：
文献类型：
--
作者：
Obashi, Kazuki;Okabe, Shigeo
轴突线粒体的正确分布对于多种神经元功能至关重要。为了了解种群行为的潜在机制，需要在多个时间尺度上对元素动力学进行定量表征。在这里，我们使用培养的小鼠海马神经元的活细胞成像研究了轴突线粒体的稳定性和运输。我们首先表征了静止线粒体的长期稳定性。在特定时刻，大约 10% 的线粒体处于运输状态，其余 90% 处于静止状态。在这些静止的线粒体中，40% 的线粒体在几天内保持在同一位置。线粒体的其余部分随机转变为移动状态，并且可以通过间隔 30 分钟的延时成像来检测和定量分析该过程。培养2至3周后，轴突线粒体的稳定性增加，河豚毒素处理后稳定性降低，突触附近更高。静止线粒体应通过移动线粒体的暂停和随后的稳定来产生。因此，我们接下来通过 0.3 Hz 的重复成像来分析移动线粒体的暂停事件。我们发现，短暂停顿的概率随着场刺激而增加，随着河豚毒素治疗而降低，并且在突触附近更高。最后，通过结合不同时间尺度的延时成像获得的参数，我们可以估计不同线粒体状态之间的转变率。分析表明，暂停线粒体转变为静止状态的可能性存在特定的发育调节。这些发现表明，多种线粒体行为，尤其是受神经元活动和突触位置调节的线粒体行为，决定了它们在轴突中的分布。
Proper distribution of axonal mitochondria is critical for multiple neuronal functions. To understand the underlying mechanisms for population behavior, quantitative characterisation of elemental dynamics on multiple time scales is required. Here we investigated the stability and transport of axonal mitochondria using live-cell imaging of cultured mouse hippocampal neurons. We first characterised the long-term stability of stationary mitochondria. At a given moment, about 10% of the mitochondria were in a state of transport and the remaining 90% were stationary. Among these stationary mitochondria, 40% of them remained in the same position over several days. The rest of the mitochondria transited to mobile state stochastically and this process could be detected and quantitatively analysed by time-lapse imaging with intervals of 30 min. The stability of axonal mitochondria increased from 2 to 3 weeks in culture, was decreased by tetrodotoxin treatment, and was higher near synapses. Stationary mitochondria should be generated by pause of moving mitochondria and subsequent stabilisation. Therefore, we next analysed pause events of moving mitochondria by repetitive imaging at 0.3 Hz. We found that the probability of transient pause increased with field stimulation, decreased with tetrodotoxin treatment, and was higher near synapses. Finally, by combining parameters obtained from time-lapse imaging with different time scales, we could estimate transition rates between different mitochondrial states. The analyses suggested specific developmental regulation in the probability of paused mitochondria to transit into stationary state. These findings indicate that multiple mitochondrial behaviors, especially those regulated by neuronal activity and synapse location, determine their distribution in the axon.