Localization, trafficking, and signaling of trace amine-associated receptor 2 in mouse neuroblastoma cells

Trace amine-associated receptors (TAARs) are a family of G protein-coupled receptors increasingly recognized for their role in modulating neurotransmission. Among the TAAR isoforms, TAAR2 remains poorly understood despite growing appreciation of its involvement in neurological disorders. In this study, we characterized the subcellular localization and agonist-induced trafficking dynamics of TAAR2 in mouse Neuro-2a cells stably expressing N-terminal His-tagged TAAR2. Under basal conditions, immunocytochemical analysis revealed that TAAR2 was predominantly localized intracellularly. Upon stimulation with β-phenethylamine (β-PEA), a pan-TAAR agonist, TAAR2 underwent rapid and dynamic redistribution across subcellular compartments. Specifically, within 5 min, TAAR2 exited the endoplasmic reticulum (ER) and accumulated in the Golgi. By 10-20 min, its localization in the ER and Golgi returned to baseline, while TAAR2 slowly translocated to the plasma membrane, reaching peak surface expression at 20 min. Functional assays demonstrated that TAAR2 coupled to Gαi/o proteins, but not Gαs proteins, as evidenced by β-PEA-induced inhibition of forskolin-stimulated cAMP production. Notably, this inhibition became significant at 20 min of agonist treatment, coinciding with peak plasma membrane localization of TAAR2 following agonist treatment. Together, these findings establish a clear temporal link between TAAR2 trafficking and signaling, suggesting that subcellular localization is tightly coupled to receptor function. This study provides the first characterization of TAAR2's trafficking and signaling in a neuronal-like context, laying the groundwork for future investigations into its role in neurological disorders.