Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA.
Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA; Department of Pharmacology, Nanjing Medical University, Nanjing, China.
J Biol Chem. 2021 Jan-Jun;296:100517. doi: 10.1016/j.jbc.2021.100517. Epub 2021 Mar 4.
G protein-coupled receptors (GPCRs) are important modulators of synaptic functions. A fundamental but poorly addressed question in neurobiology is how targeted GPCR trafficking is achieved. Rab GTPases are the master regulators of vesicle-mediated membrane trafficking, but their functions in the synaptic presentation of newly synthesized GPCRs are virtually unknown. Here, we investigate the role of Rab43, via dominant-negative inhibition and CRISPR-Cas9-mediated KO, in the export trafficking of α-adrenergic receptor (α-AR) and muscarinic acetylcholine receptor (mAChR) in primary neurons and cells. We demonstrate that Rab43 differentially regulates the overall surface expression of endogenous α-AR and mAChR, as well as their signaling, in primary neurons. In parallel, Rab43 exerts distinct effects on the dendritic and postsynaptic transport of specific α-AR and M3 mAChR subtypes. More interestingly, the selective actions of Rab43 toward α-AR and M3 mAChR are neuronal cell specific and dictated by direct interaction. These data reveal novel, neuron-specific functions for Rab43 in the dendritic and postsynaptic targeting and sorting of GPCRs and imply multiple forward delivery routes for different GPCRs in neurons. Overall, this study provides important insights into regulatory mechanisms of GPCR anterograde traffic to the functional destination in neurons.
G 蛋白偶联受体（GPCRs）是突触功能的重要调节剂。神经生物学中一个基本但尚未得到解决的问题是如何实现靶向 GPCR 运输。Rab GTPases 是囊泡介导的膜运输的主要调节剂，但它们在新合成的 GPCR 突触呈现中的功能实际上是未知的。在这里，我们通过显性负抑制和 CRISPR-Cas9 介导的 KO 研究 Rab43 在原代神经元和细胞中 α-肾上腺素能受体（α-AR）和毒蕈碱乙酰胆碱受体（mAChR）的输出运输中的作用。我们证明 Rab43 可在原代神经元中差异调节内源性 α-AR 和 mAChR 的整体表面表达及其信号转导。平行地，Rab43 对特定的 α-AR 和 M3 mAChR 亚型的树突和突触后运输产生不同的影响。更有趣的是，Rab43 对 α-AR 和 M3 mAChR 的选择性作用是神经元细胞特异性的，并由直接相互作用决定。这些数据揭示了 Rab43 在 GPCR 树突和突触后靶向和分拣中的新型、神经元特异性功能，并暗示神经元中不同 GPCR 存在多个正向递药途径。总的来说，这项研究为 GPCR 顺行运输到神经元中的功能目的地的调控机制提供了重要的见解。
