Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany.
Neuron. 2022 Jan 19;110(2):248-265.e9. doi: 10.1016/j.neuron.2021.10.028. Epub 2021 Nov 11.
Despite the importance of dopamine for striatal circuit function, mechanistic understanding of dopamine transmission remains incomplete. We recently showed that dopamine secretion relies on the presynaptic scaffolding protein RIM, indicating that it occurs at active zone-like sites similar to classical synaptic vesicle exocytosis. Here, we establish using a systematic gene knockout approach that Munc13 and Liprin-α, active zone proteins for vesicle priming and release site organization, are important for dopamine secretion. Furthermore, RIM zinc finger and CB domains, which bind to Munc13 and Liprin-α, respectively, are needed to restore dopamine release after RIM ablation. In contrast, and different from typical synapses, the active zone scaffolds RIM-BP and ELKS, and RIM domains that bind to them, are expendable. Hence, dopamine release necessitates priming and release site scaffolding by RIM, Munc13, and Liprin-α, but other active zone proteins are dispensable. Our work establishes that efficient release site architecture mediates fast dopamine exocytosis.
尽管多巴胺对纹状体回路功能很重要，但对多巴胺传递的机制理解仍不完整。我们最近表明，多巴胺的分泌依赖于突触前支架蛋白 RIM，这表明它发生在类似于经典突触小泡胞吐的活性区样部位。在这里，我们通过系统的基因敲除方法确立了，囊泡引发和释放部位组织的活性区蛋白 Munc13 和 Liprin-α，对于多巴胺的分泌很重要。此外，分别与 Munc13 和 Liprin-α结合的 RIM 锌指和 CB 结构域，对于 RIM 缺失后多巴胺的释放的恢复是必需的。相比之下，与典型的突触不同，活性区支架 RIM-BP 和 ELKS，以及与它们结合的 RIM 结构域，是可有可无的。因此，多巴胺的释放需要 RIM、Munc13 和 Liprin-α进行囊泡引发和释放部位支架的搭建，但其他的活性区蛋白是可有可无的。我们的工作确立了有效的释放部位结构介导快速多巴胺胞吐。
