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Receptor conformations involved in dopamine D(2L) receptor functional selectivity induced by selected transmembrane-5 serine mutations.

ABSTRACT: Although functional selectivity is now widely accepted, the molecular basis is poorly understood. We have studied how aspects of transmembrane region 5 (TM5) of the dopamine D(2L) receptor interacts with three rationally selected rigid ligands (dihydrexidine, dinapsoline, and dinoxyline) and the reference compounds dopamine and quinpirole. As was expected from homology modeling, mutation of three TM5 serine residues to alanine (S5.42A, S5.43A, S5.46A) had little effect on antagonist affinity. All three mutations decreased the affinity of the agonist ligands to different degrees, S5.46A being somewhat less affected. Four functions [adenylate cyclase (AC), extracellular signal-regulated kinase 1/2 phosphorylation (MAPK), arachidonic acid release (AA), and guanosine 5'-O-(3-thio)triphosphate binding (GTP?S)] were assessed. The intrinsic activity (IA) of quinpirole was unaffected by any of the mutations, whereas S5.42A and S5.46A mutations abolished the activity of dopamine and the three rigid ligands, although dihydrexidine retained IA at MAPK function only with S5.42A. Remarkably, S5.43A did not markedly affect IA for AC and MAPK for any of the ligands and eliminated AA activity for dinapsoline and dihydrexidine but not dinoxyline. These data suggest that this mutation did not disrupt the overall conformation or signaling ability of the mutant receptors but differentially affected ligand activation. Computational studies indicate that these D(2) agonists stabilize multiple receptor conformations. This has led to models showing the stabilized conformations and interhelical and receptor-ligand contacts corresponding to the different activation pathways stabilized by various agonists. These data provide a basis for understanding D(2L) functional selectivity and rationally discovering functionally selective D(2) drugs.

SUBMITTER: Fowler JC

PROVIDER: S-EPMC3362898 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

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Receptor conformations involved in dopamine D(2L) receptor functional selectivity induced by selected transmembrane-5 serine mutations.

Fowler J Corey JC Bhattacharya Supriyo S Urban Jonathan D JD Vaidehi Nagarajan N Mailman Richard B RB

Molecular pharmacology 20120313 6

Although functional selectivity is now widely accepted, the molecular basis is poorly understood. We have studied how aspects of transmembrane region 5 (TM5) of the dopamine D(2L) receptor interacts with three rationally selected rigid ligands (dihydrexidine, dinapsoline, and dinoxyline) and the reference compounds dopamine and quinpirole. As was expected from homology modeling, mutation of three TM5 serine residues to alanine (S5.42A, S5.43A, S5.46A) had little effect on antagonist affinity. Al ...[more]

PMID: 22416052

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Project description:Functional selectivity (or biased agonism) is a property exhibited by some G protein-coupled receptor (GPCR) ligands, which results in the modulation of a subset of a receptor's signaling capabilities and more precise control over complex biological processes. The dopamine D2 receptor (D2R) exhibits pleiotropic responses to the biogenic amine dopamine (DA) to mediate complex central nervous system functions through activation of G proteins and β-arrestins. D2R is a prominent therapeutic target for psychological and neurological disorders in which DA biology is dysregulated and targeting D2R with functionally selective drugs could provide a means by which pharmacotherapies could be developed. However, factors that determine GPCR functional selectivity in vivo may be multiple with receptors, ligands and transducers contributing to the process. We have recently described a mutagenesis approach to engineer biased D2R mutants in which G protein-dependent ([Gprot]D2R) and β-arrestin-dependent signaling ([βarr]D2R) were successfully separated (Peterson, et al. PNAS, 2015). Here, permutations of these mutants were used to identify critical determinants of the D2R signaling complex that impart signaling bias in response to the natural or synthetic ligands. Critical residues identified in generating [Gprot]D2R and [βarr]D2R conferred control of partial agonism at G protein and/or β-arrestin activity. Another set of mutations that result in G protein bias was identified that demonstrated that full agonists can impart unique activation patterns, and provided further credence to the concept of ligand texture. Finally, the contributions and interplay between different transducers indicated that G proteins are not aberrantly activated, and that receptor kinase and β-arrestin activities are inextricably linked. These data provide a thorough elucidation of the feasibility and malleability of D2R functional selectivity and point to means by which novel in vivo therapies could be modeled.

Project description:Dopamine receptors are integral membrane proteins whose endogenous ligand is dopamine. They play a fundamental role in the central nervous system and dysfunction of dopaminergic neurotransmission is responsible for the generation of a variety of neuropsychiatric disorders. From an evolutionary standpoint, phylogenetic relationships among the DRD1 class of dopamine receptors are still a matter of debate as in the literature different tree topologies have been proposed. In contrast, phylogenetic relationships among the DRD 2 group of receptors are well understood. Understanding the time of origin of the different dopamine receptors is also an issue that needs further study, especially for the genes that have restricted phyletic distributions (e.g., DRD2l and DRD4rs). Thus, the goal of this study was to investigate the evolution of dopamine receptors, with emphasis on shedding light on the phylogenetic relationships among the D1 class of dopamine receptors and the time of origin of the DRD2l and DRD4rs gene lineages. Our results recovered the monophyly of the two groups of dopamine receptors. Within the DRD1 group the monophyly of each paralog was recovered with strong support, and phylogenetic relationships among them were well resolved. Within the DRD1 class of dopamine receptors we recovered the sister group relationship between the DRD1C and DRD1E, and this clade was recovered sister to a cyclostome sequence. The DRD1 clade was recovered sister to the aforementioned clade, and the group containing DRD5 receptors was sister to all other DRD1 paralogs. In agreement with the literature, among the DRD2 class of receptors, DRD2 was recovered sister to DRD3, whereas DRD4 was sister to the DRD2/DRD3 clade. According to our phylogenetic tree, the DRD2l and DRD4rs gene lineages would have originated in the ancestor of gnathostomes between 615 and 473 mya. Conservation of sequences required for dopaminergic neurotransmission and small changes in regulatory regions suggest a functional refinement of the dopaminergic pathways along evolution.

Dataset Information

Receptor conformations involved in dopamine D(2L) receptor functional selectivity induced by selected transmembrane-5 serine mutations.

Publications

Receptor conformations involved in dopamine D(2L) receptor functional selectivity induced by selected transmembrane-5 serine mutations.

Similar Datasets

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