title: Elucidation of G-protein and β-arrestin functional selectivity at the dopamine D2 receptor.
abstract: The neuromodulator dopamine signals through the dopamine D2 receptor (D2R) to modulate central nervous system functions through diverse signal transduction pathways. D2R is a prominent target for drug treatments in disorders where dopamine function is aberrant, such as schizophrenia. D2R signals through distinct G-protein and β-arrestin pathways, and drugs that are functionally selective for these pathways could have improved therapeutic potential. How D2R signals through the two pathways is still not well defined, and efforts to elucidate these pathways have been hampered by the lack of adequate tools for assessing the contribution of each pathway independently. To address this, Evolutionary Trace was used to produce D2R mutants with strongly biased signal transduction for either the G-protein or β-arrestin interactions. These mutants were used to resolve the role of G proteins and β-arrestins in D2R signaling assays. The results show that D2R interactions with the two downstream effectors are dissociable and that G-protein signaling accounts for D2R canonical MAP kinase signaling cascade activation, whereas β-arrestin only activates elements of this cascade under certain conditions. Nevertheless, when expressed in mice in GABAergic medium spiny neurons of the striatum, the β-arrestin-biased D2R caused a significant potentiation of amphetamine-induced locomotion, whereas the G protein-biased D2R had minimal effects. The mutant receptors generated here provide a molecular tool set that should enable a better definition of the individual roles of G-protein and β-arrestin signaling pathways in D2R pharmacology, neurobiology, and associated pathologies.
authors.affiliation: Departments of Cell Biology.
authors.forename: Sean M
authors.initials: SM
authors.lastname: Peterson
authors.affiliation: Departments of Cell Biology.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Pack
authors.affiliation: Department of Molecular and Human Genetics and Computational and Integrative Biomedical Research Center, Baylor College of Medicine, Houston, TX 77030; and.
authors.forename: Angela D
authors.initials: AD
authors.lastname: Wilkins
authors.affiliation: Departments of Cell Biology.
authors.forename: Nikhil M
authors.initials: NM
authors.lastname: Urs
authors.affiliation: Departments of Cell Biology.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Urban
authors.affiliation: Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14214.
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Bass
authors.affiliation: Department of Molecular and Human Genetics and Computational and Integrative Biomedical Research Center, Baylor College of Medicine, Houston, TX 77030; and.
authors.forename: Olivier
authors.initials: O
authors.lastname: Lichtarge
authors.affiliation: Departments of Cell Biology, Medicine, and Neurobiology, Duke University School of Medicine, Durham, NC 27710; marc.caron@dm.duke.edu.
authors.forename: Marc G
authors.initials: MG
authors.lastname: Caron
mesh_terms: D000818:Animals; D019390:Arrestins / Q000737:chemistry / Q000378:metabolism*; D003342:Corpus Striatum / Q000166:cytology; D003461:Crystallography; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D020935:MAP Kinase Signaling System / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008958:Models, Molecular; D016296:Mutagenesis; D009474:Neurons / Q000378:metabolism; D011487:Protein Conformation; D017448:Receptors, Dopamine D2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012044:Regression Analysis; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D017448:Receptors, Dopamine D2; D000071557:beta-Arrestins; D019204:GTP-Binding Proteins
keywords: G protein; GPCR; dopamine; functional selectivity; β-arrestin