TY - JOUR T1 - Role of SAP97 in the Regulation of 5-HT<sub>2A</sub>R Endocytosis and Signaling JF - Molecular Pharmacology JO - Mol Pharmacol SP - 275 LP - 283 DO - 10.1124/mol.114.093476 VL - 86 IS - 3 AU - Henry A. Dunn AU - Cornelia Walther AU - George Y. Yuan AU - Fabiana A. Caetano AU - Christina M. Godin AU - Stephen S. G. Ferguson Y1 - 2014/09/01 UR - http://molpharm.aspetjournals.org/content/86/3/275.abstract N2 - Serotonin (5-HT) interacts with a wide variety of 5-HT receptors (5-HTR) of which 5-HT2AR plays an important target for antidepressant and atypical antipsychotic drugs. The carboxyl-terminal tail of 5-HT2AR encodes a motif that mediates interactions with PSD-95/disc large/zona occludens (PDZ) domain–containing proteins. In the present study, we found that 5-HT2AR interacts with synapse-associated protein 97 (SAP97; also known as DLG1) by coimmunoprecipitation in human embryonic 293 (HEK 293) cells and cortical brain lysates. We found that 5-HT2AR expression results in the recruitment of SAP97 from the cytosol to the plasma membrane and that this recruitment is dependent on an intact 5-HT2AR PDZ binding motif. We also show that 5-HT2AR interacts with SAP97 using bioluminescence energy transfer and that overexpression of SAP97 retards 5-HT2AR endocytosis, while single hairpin RNA knockdown facilitates 5-HT2AR internalization. The knockdown of SAP97 in HEK 293 cells results in a reduction in the maximum efficacy for 5-HT2AR-stimulated inositol phosphate formation and that the deletion of the 5-HT2AR PDZ motif also impairs 5-HT2AR signaling. Similarly to what has been observed for the corticotropin-releasing factor receptor 1 (CRFR1), SAP97 expression is essential for 5-HT2AR-stimulated extracellular-regulated protein kinase 1/2 (ERK1/2) phosphorylation by a PDZ interaction-independent mechanism. Moreover, we find that SAP97 is not responsible for CRFR1-mediated sensitization of 5-HT2AR signaling. Taken together, our studies show that SAP97 plays a conserved role in regulating 5-HT2AR endocytosis and ERK1/2 signaling, but plays a novel role in regulating 5-HT2AR G protein coupling. ER -