Serotonin 5-HT2C Receptor Signaling Analysis Reveals Psychedelic Biased Agonism.

The serotonin 2C receptor (5-HT 2C ) is involved in processes like mood and appetite and is a target for drugs treating obesity, addiction, and depression, including psychedelics. This analysis of 5-HT 2C signaling confirms that the receptor activates multiple G protein pathways—Gi/o/z and G12/13 in addition to its main Gq/11 pathway—and preferentially recruits β-arrestin2 over β-arrestin1. Increased RNA editing of the receptor reduces signaling across all G protein pathways, especially G12/13, while preserving β-arrestin recruitment. Profiling of ligands shows that psychedelics like LSD and psilocin produce a strong Gq/11 bias by minimally activating other G proteins. These findings provide a foundation for considering broader signaling modalities in 5-HT 2C drug development.

Study at a glance

Abstract

The serotonin 2C receptor (5-HT 2C ) is a G protein-coupled receptor implicated in multiple physiological and psychological processes and has been investigated as a therapeutic target for neuropsychiatric conditions such as obesity, drug abuse, and depression. With renewed interest in serotonergic psychedelics for treating depression, 5-HT 2C may contribute to psychedelic-induced therapeutic effects. Despite earlier evidence of 5-HT 2C G protein coupling promiscuity, the full signaling landscape remains incompletely characterized, which may help explain the limited efficacy and potential cancer risks associated with lorcaserin. Here, we provide a comprehensive analysis of 5-HT 2C signaling, confirming and building upon previous findings that the receptor engages Gi/o/z and G12/13 proteins in addition to its primary Gq/11 pathway, and that it preferentially recruits β-arrestin2 over β-arrestin1. We also show that increased RNA editing of the receptor attenuates signaling across all G protein pathways, particularly for G12/13, while preserving β-arrestin recruitment. Profiling of both 5-HT 2C -selective and psychedelic ligands reveals diverse signaling profiles, with serotonergic psychedelics such as LSD and psilocin exhibiting a striking Gq/11 bias due to minimal secondary G protein activation. Altogether, this work provides a foundation for incorporating a broader view of 5-HT 2C signaling modalities into future investigations of 5-HT 2C drug development efforts.