Department of Pharmacology, University of MichiganMedical School, Ann Arbor, MI, USA.
J Cell Biol. 2023 Jul 3;222(7). doi: 10.1083/jcb.202207070. Epub 2023 Apr 6.
Vesicle fusion at the plasma membrane is critical for releasing hormones and neurotransmitters and for delivering the cognate G protein-coupled receptors (GPCRs) to the cell surface. The SNARE fusion machinery that releases neurotransmitters has been well characterized. In contrast, the fusion machinery that delivers GPCRs is still unknown. Here, using high-speed multichannel imaging to simultaneously visualize receptors and v-SNAREs in real time in individual fusion events, we identify VAMP2 as a selective v-SNARE for GPCR delivery. VAMP2 was preferentially enriched in vesicles that mediate the surface delivery of μ opioid receptor (MOR), but not other cargos, and was required selectively for MOR recycling. Interestingly, VAMP2 did not show preferential localization on MOR-containing endosomes, suggesting that v-SNAREs are copackaged with specific cargo into separate vesicles from the same endosomes. Together, our results identify VAMP2 as a cargo-selective v-SNARE and suggest that surface delivery of specific GPCRs is mediated by distinct fusion events driven by distinct SNARE complexes.
在质膜融合对于释放激素和神经递质以及将同源 G 蛋白偶联受体（GPCR）递送到细胞表面至关重要。释放神经递质的 SNARE 融合机制已经得到很好的描述。相比之下，递呈 GPCR 的融合机制仍不清楚。在这里，我们使用高速多通道成像技术在单个融合事件中实时同时可视化受体和 v-SNARE，鉴定 VAMP2 是 GPCR 递呈的选择性 v-SNARE。VAMP2 优先富集在介导 μ 阿片受体（MOR）表面递呈的囊泡中，但不富集其他货物，并且对 MOR 回收是必需的。有趣的是，VAMP2 并没有优先定位于含有 MOR 的内体上，这表明 v-SNARE 与特定货物一起被包装在来自同一内体的不同囊泡中。总之，我们的结果鉴定了 VAMP2 作为一种货物选择性 v-SNARE，并表明特定 GPCR 的表面递呈是由不同 SNARE 复合物驱动的不同融合事件介导的。
