title: Evidence against dopamine D1/D2 receptor heteromers.
abstract: Hetero-oligomers of G-protein-coupled receptors have become the subject of intense investigation, because their purported potential to manifest signaling and pharmacological properties that differ from the component receptors makes them highly attractive for the development of more selective pharmacological treatments. In particular, dopamine D1 and D2 receptors have been proposed to form hetero-oligomers that couple to Gαq proteins, and SKF83959 has been proposed to act as a biased agonist that selectively engages these receptor complexes to activate Gαq and thus phospholipase C. D1/D2 heteromers have been proposed as relevant to the pathophysiology and treatment of depression and schizophrenia. We used in vitro bioluminescence resonance energy transfer, ex vivo analyses of receptor localization and proximity in brain slices, and behavioral assays in mice to characterize signaling from these putative dimers/oligomers. We were unable to detect Gαq or Gα11 protein coupling to homomers or heteromers of D1 or D2 receptors using a variety of biosensors. SKF83959-induced locomotor and grooming behaviors were eliminated in D1 receptor knockout (KO) mice, verifying a key role for D1-like receptor activation. In contrast, SKF83959-induced motor responses were intact in D2 receptor and Gαq KO mice, as well as in knock-in mice expressing a mutant Ala(286)-CaMKIIα that cannot autophosphorylate to become active. Moreover, we found that, in the shell of the nucleus accumbens, even in neurons in which D1 and D2 receptor promoters are both active, the receptor proteins are segregated and do not form complexes. These data are not compatible with SKF83959 signaling through Gαq or through a D1/D2 heteromer and challenge the existence of such a signaling complex in the adult animals that we used for our studies.
authors.affiliation: Neuroscience Graduate Program, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Frederick
authors.affiliation: Departments of Psychiatry and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
authors.forename: H
authors.initials: H
authors.lastname: Yano
authors.affiliation: Nutrition and Integrative Neurobiology, INRA UMR 1286; University of Bordeaux, Bordeaux, France.|Department of Neuroscience, Columbia University, New York, NY, USA.
authors.forename: P
authors.initials: P
authors.lastname: Trifilieff
authors.affiliation: Department of Neuroscience, Columbia University, New York, NY, USA.
authors.forename: H D
authors.initials: HD
authors.lastname: Vishwasrao
authors.affiliation: Departments of Psychiatry and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
authors.forename: D
authors.initials: D
authors.lastname: Biezonski
authors.affiliation: Departments of Psychiatry and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
authors.forename: J
authors.initials: J
authors.lastname: Mészáros
authors.affiliation: Departments of Psychiatry and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
authors.forename: E
authors.initials: E
authors.lastname: Urizar
authors.affiliation: Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
authors.forename: D R
authors.initials: DR
authors.lastname: Sibley
authors.affiliation: Departments of Psychiatry and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.|Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA.
authors.forename: C
authors.initials: C
authors.lastname: Kellendonk
authors.affiliation: Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, MA, USA.
authors.forename: K C
authors.initials: KC
authors.lastname: Sonntag
authors.affiliation: Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Graham
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA.|Vanderbilt Kennedy Center and Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Colbran
authors.affiliation: Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.|Vanderbilt Kennedy Center and Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: G D
authors.initials: GD
authors.lastname: Stanwood
authors.affiliation: Departments of Psychiatry and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.|Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Javitch
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism; D018491:Dopamine Agonists / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000235:genetics / Q000378:metabolism*; D006120:Grooming / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008958:Models, Molecular; D009043:Motor Activity / Q000187:drug effects / Q000235:genetics; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D055503:Protein Multimerization / Q000187:drug effects / Q000502:physiology*; D017434:Protein Structure, Tertiary; D017447:Receptors, Dopamine D1 / Q000235:genetics / Q000378:metabolism*; D017448:Receptors, Dopamine D2 / Q000235:genetics / Q000378:metabolism*
chemical_list: D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D008164:Luminescent Proteins; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; C080703:SK&F 83959; D043802:GTP-Binding Protein alpha Subunits, Gq-G11