Identification of nicotinic acetylcholine receptor recycling and its role in maintaining receptor density at the neuromuscular junction in vivo
Identification of nicotinic acetylcholine receptor recycling and its role in maintaining receptor density at the neuromuscular junction in vivo
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DOI：
10.1523/jneurosci.3169-05.2005
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发表时间：
2005-10-26
影响因子：
5.3
通讯作者：
Akaaboune, M
中科院分区：
文献类型：
--
作者：
Bruneau, E;Sutter, D;Akaaboune, M
在中枢神经系统中，受体再循环对突触可塑性至关重要;然而，在外周突触中从未观察到受体的再循环。使用一种新的成像技术，我们在这里表明，烟碱乙酰胆碱受体（AChRs）回收到突触后膜的神经肌肉接头。通过用生物素-银环蛇毒素和链霉抗生物素蛋白-荧光团缀合物顺序标记AChR，我们能够区分活小鼠突触处回收的、预先存在的和新的受体池。延时成像显示，回收的AChR在最初标记的几个小时内被纳入突触，并且它们的数量随着时间的推移而增加。在功能齐全的突触，乙酰胆碱受体回收是强大的，并与新合成的受体插入的幅度相当，而慢性突触活动阻滞几乎废除受体回收。最后，使用相同的顺序标记方法，我们发现乙酰胆碱酯酶，另一个突触成分，不回收。这些结果确定了一种活性依赖性AChR再循环机制，该机制能够调节受体密度，这可能导致突触功效的快速改变。
In the CNS, receptor recycling is critical for synaptic plasticity; however, the recycling of receptors has never been observed at peripheral synapses. Using a novel imaging technique, we show here that nicotinic acetylcholine receptors (AChRs) recycle into the postsynaptic membrane of the neuromuscular junction. By sequentially labeling AChRs with biotin-bungarotoxin and streptavidin-fluorophore conjugates, we were able to distinguish recycled, preexisting, and new receptor pools at synapses in living mice. Time-lapse imaging revealed that recycled AChRs were incorporated into the synapse within hours of initial labeling, and their numbers increased with time. At fully functional synapses, AChR recycling was robust and comparable in magnitude with the insertion of newly synthesized receptors, whereas chronic synaptic activity blockade nearly abolished receptor recycling. Finally, using the same sequential labeling method, we found that acetylcholinesterase, another synaptic component, does not recycle. These results identify an activity-dependent AChR-recycling mechanism that enables the regulation of receptor density, which could lead to rapid alterations in synaptic efficacy.