Mechanical actions of dendritic-spine enlargement on presynaptic exocytosis
Mechanical actions of dendritic-spine enlargement on presynaptic exocytosis
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DOI：
10.1038/s41586-021-04125-7
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发表时间：
2021-11
期刊：
影响因子：
64.8
通讯作者：
H. Ucar;Satoshi Watanabe;J. Noguchi;Yuichi Morimoto;Y. Iino;Sho Yagishita;N. Takahashi;H. Kasai-
中科院分区：
文献类型：
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作者：
H. Ucar;Satoshi Watanabe;J. Noguchi;Yuichi Morimoto;Y. Iino;Sho Yagishita;N. Takahashi;H. Kasai-
突触传递涉及两个神经元之间突触连接处的细胞间通信，这一过程的化学和电形式已被广泛研究。在大脑中，兴奋性谷氨酸能突触通常是在树突棘上形成的，在学习过程中树突棘会扩大，，，-。由于树突棘和突触前末梢与突触间隙紧密相连，其增大可能对突触前功能产生机械效应。在这里，我们发现，用玻璃移液管对突触前扣进行精细和短暂的推动，可以显著促进谷氨酸的诱发释放和SNARE（可溶性乙基丙烯酰亚胺敏感因子附着蛋白受体）蛋白的组装，-通过Förster共振转移（FRET）和荧光寿命成像在大鼠片培养制备中测量。这两种效果都持续了20多分钟。突触前FRET的增加与胞质钙（Ca2+）无关，但依赖于钮扣中SNARE蛋白的组装和肌动蛋白的聚合。值得注意的是，低高渗蔗糖溶液（20 mM）对FRET和诱发释放均有促进作用，但不诱导自发释放，与高渗蔗糖溶液（300 mM）形成鲜明对比，高渗蔗糖溶液本身诱导胞吐。最后，双光子谷氨酸释放诱导的脊柱增大，只有当脊柱伸长推动钮扣时，才会增加诱发释放和FRET。因此，我们已经确定了突触前钮扣中的机械感觉和转导机制，其中诱发的谷氨酸释放增强超过20分钟。
Synaptic transmission involves cell-to-cell communication at the synaptic junction between two neurons, and chemical and electrical forms of this process have been extensively studied. In the brain, excitatory glutamatergic synapses are often made on dendritic spines that enlarge during learning, , , –. As dendritic spines and the presynaptic terminals are tightly connected with the synaptic cleft, the enlargement may have mechanical effects on presynaptic functions. Here we show that fine and transient pushing of the presynaptic boutons with a glass pipette markedly promotes both the evoked release of glutamate and the assembly of SNARE (solubleN-ethylmaleimide-sensitive factor attachment protein receptor) proteins, , , –—as measured by Förster resonance transfer (FRET) and fluorescence lifetime imaging—in rat slice culture preparations. Both of these effects persisted for more than 20 minutes. The increased presynaptic FRET was independent of cytosolic calcium (Ca2+), but dependent on the assembly of SNARE proteins and actin polymerization in the boutons. Notably, a low hypertonic solution of sucrose (20 mM) had facilitatory effects on both the FRET and the evoked release without inducing spontaneous release, in striking contrast with a high hypertonic sucrose solution (300 mM), which induced exocytosis by itself. Finally, spine enlargement induced by two-photon glutamate uncaging enhanced the evoked release and the FRET only when the spines pushed the boutons by their elongation. Thus, we have identified a mechanosensory and transduction mechanism in the presynaptic boutons, in which the evoked release of glutamate is enhanced for more than 20 min.