Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), Amsterdam Neuroscience, VU University Medical Center, Amsterdam, Netherlands.
Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) Amsterdam, de Boelelaan 1087, 1081 HV Amsterdam, Netherlands.
Sci Adv. 2021 May 21;7(21). doi: 10.1126/sciadv.abf0659. Print 2021 May.
Synaptic vesicles (SVs) release neurotransmitters at specialized active zones, but release sites and organizing principles for the other major secretory pathway, neuropeptide/neuromodulator release from dense-core vesicles (DCVs), remain elusive. We identify dynamins, yeast Vps1 orthologs, as DCV fusion site organizers in mammalian neurons. Genetic or pharmacological inactivation of all three dynamins strongly impaired DCV exocytosis, while SV exocytosis remained unaffected. Wild-type dynamin restored normal exocytosis but not guanosine triphosphatase-deficient or membrane-binding mutants that cause neurodevelopmental syndromes. During prolonged stimulation, repeated use of the same DCV fusion location was impaired in dynamin 1-3 triple knockout neurons. The syntaxin-1 staining efficiency, but not its expression level, was reduced. αSNAP (α-soluble -ethylmaleimide-sensitive factor attachment protein) expression restored this. We conclude that mammalian dynamins organize DCV fusion sites, downstream of αSNAP, by regulating the equilibrium between fusogenic and non-fusogenic syntaxin-1 promoting its availability for SNARE (SNAP receptor) complex formation and DCV exocytosis.
突触小泡 (SVs) 在特化的活性区释放神经递质，但其他主要分泌途径——从致密核心囊泡 (DCVs) 释放神经肽/神经调质的释放位点和组织原则仍不清楚。我们鉴定出胞质动力蛋白，酵母 Vps1 同源物，作为哺乳动物神经元中 DCV 融合位点的组织者。三种胞质动力蛋白的遗传或药理学失活都强烈损害了 DCV 的胞吐作用，而 SV 的胞吐作用不受影响。野生型动力蛋白恢复了正常的胞吐作用，但不能恢复引起神经发育综合征的 GTPase 缺陷或膜结合突变体。在长时间刺激期间，在 dynamin 1-3 三重敲除神经元中，相同的 DCV 融合位置的重复使用受到损害。突触结合蛋白 1（syntaxin-1）的染色效率降低，但其表达水平没有降低。αSNAP（α-可溶的 -乙基马来酰亚胺敏感因子附着蛋白）的表达恢复了这一点。我们得出结论，哺乳动物的动力蛋白通过调节融合和非融合的 syntaxin-1 之间的平衡来组织 DCV 融合位点，αSNAP 位于下游，促进其用于 SNARE（SNAP 受体）复合物形成和 DCV 胞吐作用。
