Neural Activity Selects Myosin IIB and VI with a Specific Time Window in Distinct Dynamin Isoform-Mediated Synaptic Vesicle Reuse Pathways
Neural Activity Selects Myosin IIB and VI with a Specific Time Window in Distinct Dynamin Isoform-Mediated Synaptic Vesicle Reuse Pathways
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DOI：
10.1523/jneurosci.5028-14.2015
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发表时间：
2015-06-10
影响因子：
5.3
通讯作者：
Mochida, Sumiko
中科院分区：
文献类型：
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作者：
Hayashida, Michikata;Tanifuji, Shota;Mochida, Sumiko
突触前神经末梢必须通过突触囊泡（SV）再供应维持稳定的神经传递，尽管遇到传入动作电位（ap）的数量和频率的广泛波动。然而，神经活动变化与SV再供给之间的分子机制尚不清楚。肌凝蛋白II和VI是基于肌动蛋白的细胞骨架马达，分别驱动脑突触的树突肌动蛋白动力学和膜运输。本研究将基因敲除或分子功能障碍与培养的配对大鼠颈上神经节神经元快速突触传递的直接生理测量相结合，表明肌球蛋白IIB和VI在SV重复通路中单独起作用，与生理AP频率有明显的依赖性和时间常数。肌凝蛋白VI以缓慢的动力学重新供给易释放池（RRP），与放电速率无关，但在AP后50 ms内迅速起作用。在高频AP放电下，肌凝蛋白IIB在200 ms的较慢时间窗内以快速动力学重新供给RRP。通过混合siRNA显微注射敲低myosin和dynamin亚型表明，myosin iib介导的SV再供应遵循amphiphysin/dynamin-1介导的内吞作用，而myosin vi介导的SV再供应遵循dynamin-3介导的内吞作用。总的来说，我们的研究结果表明，不同的肌球蛋白同工型如何在与特定放电模式相关的适当SV再利用途径中作为囊泡马达工作。
Presynaptic nerve terminals must maintain stable neurotransmissions via synaptic vesicle (SV) resupply despite encountering wide fluctuations in the number and frequency of incoming action potentials (APs). However, the molecular mechanism linking variation in neural activity to SV resupply is unknown. Myosins II and VI are actin-based cytoskeletal motors that drive dendritic actin dynamics and membrane transport, respectively, at brain synapses. Here we combined genetic knockdown or molecular dysfunction and direct physiological measurement of fast synaptic transmission from paired rat superior cervical ganglion neurons in culture to show that myosins IIB and VI work individually in SV reuse pathways, having distinct dependency and time constants with physiological AP frequency. Myosin VI resupplied the readily releasable pool (RRP) with slow kinetics independently of firing rates but acted quickly within 50 ms after AP. Under high-frequency AP firing, myosin IIB resupplied the RRP with fast kinetics in a slower time window of 200 ms. Knockdown of both myosin and dynamin isoforms by mixed siRNA microinjection revealed that myosin IIB-mediated SV resupply follows amphiphysin/dynamin-1-mediated endocytosis, while myosin VI-mediated SV resupply follows dynamin-3-mediated endocytosis. Collectively, our findings show how distinct myosin isoforms work as vesicle motors in appropriate SV reuse pathways associated with specific firing patterns.