Munc13 supports fusogenicity of non-docked vesicles at synapses with disrupted active zones.
Munc13 supports fusogenicity of non-docked vesicles at synapses with disrupted active zones.
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DOI：
10.7554/elife.79077
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发表时间：
2022-11-18
期刊：
影响因子：
7.7
通讯作者：
Kaeser PS
中科院分区：
文献类型：
--
作者：
Tan C;de Nola G;Qiao C;Imig C;Born RT;Brose N;Kaeser PS
活性区由紧密附着在突触前质膜上的蛋白质支架组成。它们停靠和启动突触囊泡，将它们偶联到电压门控的Ca2+通道，并将神经递质释放到突触后受体区域。同时RIM + ELKS消融破坏了这些支架，取消了囊泡对接，并去除了活性区域靶向的Munc13，但一些囊泡仍然可以释放。为了评估这种持久的囊泡融合原性是由非活性区锚定的Munc13介导还是独立于Munc13，我们切除了小鼠海马神经元中的Munc13-1和Munc13-2以及RIM + ELKS。六元敲除突触缺乏停靠的囊泡，但其他超微结构特征接近正常，尽管强烈的遗传操作。通过进一步减少可释放的囊泡池，去除Munc13和RIM + ELKS比去除RIM + ELKS更强烈地破坏了动作电位诱发的囊泡融合。因此，Munc13可以在没有RIM和ELKS的情况下支持一定的融合原性，并且即使没有活动区锚定，Munc13的突触前募集也足以产生一些融合能力囊泡。
Active zones consist of protein scaffolds that are tightly attached to the presynaptic plasma membrane. They dock and prime synaptic vesicles, couple them to voltage-gated Ca2+ channels, and direct neurotransmitter release toward postsynaptic receptor domains. Simultaneous RIM + ELKS ablation disrupts these scaffolds, abolishes vesicle docking, and removes active zone-targeted Munc13, but some vesicles remain releasable. To assess whether this enduring vesicular fusogenicity is mediated by non-active zone-anchored Munc13 or is Munc13-independent, we ablated Munc13-1 and Munc13-2 in addition to RIM + ELKS in mouse hippocampal neurons. The hextuple knockout synapses lacked docked vesicles, but other ultrastructural features were near-normal despite the strong genetic manipulation. Removing Munc13 in addition to RIM + ELKS impaired action potential-evoked vesicle fusion more strongly than RIM + ELKS knockout by further decreasing the releasable vesicle pool. Hence, Munc13 can support some fusogenicity without RIM and ELKS, and presynaptic recruitment of Munc13, even without active zone anchoring, suffices to generate some fusion-competent vesicles.