Molecular Mechanisms of Exocytosis, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany.
EMBO J. 2010 Aug 4;29(15):2477-90. doi: 10.1038/emboj.2010.130. Epub 2010 Jun 18.
The SNARE-complex consisting of synaptobrevin-2/VAMP-2, SNAP-25 and syntaxin-1 is essential for evoked neurotransmission and also involved in spontaneous release. Here, we used cultured autaptic hippocampal neurons from Snap-25 null mice rescued with mutants challenging the C-terminal, N-terminal and middle domains of the SNARE-bundle to dissect out the involvement of these domains in neurotransmission. We report that the stabilities of two different sub-domains of the SNARE-bundle have opposing functions in setting the probability for both spontaneous and evoked neurotransmission. Destabilizing the C-terminal end of the SNARE-bundle abolishes spontaneous neurotransmitter release and reduces evoked release probability, indicating that the C-terminal end promotes both modes of release. In contrast, destabilizing the middle or deleting the N-terminal end of the SNARE-bundle increases both spontaneous and evoked release probabilities. In both cases, spontaneous release was affected more than evoked neurotransmission. In addition, the N-terminal deletion delays vesicle priming after a high-frequency train. We propose that the stability of N-terminal two-thirds of the SNARE-bundle has a function for vesicle priming and limiting spontaneous release.
由突触融合蛋白 2/VAMP-2、SNAP-25 和突触融合蛋白 1 组成的 SNARE 复合物对于诱发的神经递质释放是必不可少的，并且也参与自发释放。在这里，我们使用来自 Snap-25 缺失型小鼠的培养的自突触海马神经元，这些神经元被具有挑战性的 SNARE 束的 C 末端、N 末端和中间结构域的突变体拯救，以剖析这些结构域在神经递质释放中的参与情况。我们报告说，SNARE 束的两个不同亚结构域的稳定性在设定自发和诱发神经递质释放的概率方面具有相反的功能。破坏 SNARE 束的 C 末端会消除自发神经递质释放并降低诱发释放的概率，表明 C 末端促进两种释放模式。相比之下，破坏中间或删除 SNARE 束的 N 末端会增加自发和诱发释放的概率。在这两种情况下，自发释放比诱发神经递质释放受到的影响更大。此外，N 末端缺失会延迟高频刺激后囊泡的引发。我们提出，SNARE 束 N 端三分之二的稳定性对于囊泡引发和限制自发释放具有功能。
