Residues and Residue Pairs of Evolutionary Importance Differentially Direct Signaling Bias of D2 Dopamine Receptors

Authors

María E Terrón-Díaz
Sara J Wright
Melina A Agosto
Olivier Lichtarge
Theodore G Wensel

Publication Date

12-13-2019

Journal

Journal of Biological Chemistry

DOI

10.1074/jbc.RA119.008068

PMID

31676688

PMCID

PMC6916503

PubMedCentral® Posted Date

11-1-2019

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

Cells, Cultured, Dopamine, Dose-Response Relationship, Drug, HEK293 Cells, Humans, Receptors, Dopamine D2, Serotonin, Signal Transduction, G-protein–coupled receptor (GPCR), dopamine receptor, dopamine, arrestin, allosteric regulation, G protein, cell signaling

Abstract

The D2 dopamine receptor and the serotonin 5-hydroxytryptamine 2A receptor (5-HT2A) are closely-related G-protein–coupled receptors (GPCRs) from the class A bioamine subfamily. Despite structural similarity, they respond to distinct ligands through distinct downstream pathways, whose dysregulation is linked to depression, bipolar disorder, addiction, and psychosis. They are important drug targets, and it is important to understand how their bias toward G-protein versus β-arrestin signaling pathways is regulated. Previously, evolution-based computational approaches, difference Evolutionary Trace and Evolutionary Trace–Mutual information (ET-Mip), revealed residues and residue pairs that, when switched in the D2 receptor to the corresponding residues from 5-HT2A, altered ligand potency and G-protein activation efficiency. We have tested these residue swaps for their ability to trigger recruitment of β-arrestin2 in response to dopamine or serotonin. The results reveal that the selected residues modulate agonist potency, maximal efficacy, and constitutive activity of β-arrestin2 recruitment. Whereas dopamine potency for most variants was similar to that for WT and lower than for G-protein activation, potency in β-arrestin2 recruitment for N124H3.42 was more than 5-fold higher. T205M5.54 displayed high constitutive activity, enhanced dopamine potency, and enhanced efficacy in β-arrestin2 recruitment relative to WT, and L379F6.41 was virtually inactive. These striking differences from WT activity were largely reversed by a compensating mutation (T205M5.54/L379F6.41) at residues previously identified by ET-Mip as functionally coupled. The observation that the signs and relative magnitudes of the effects of mutations in several cases are at odds with their effects on G-protein activation suggests that they also modulate signaling bias.