title: Identification of key residues involved in the activation and signaling properties of dopamine D3 receptor.
abstract: The dopamine D3 receptor exhibits agonist-dependent tolerance and slow response termination (SRT) signaling properties that distinguish it from the closely-related D2 receptors. While amino acid residues important for D3 receptor ligand binding have been identified, the residues involved in activation of D3 receptor signaling and induction of signaling properties have not been determined. In this paper, we used cis and trans isomers of a novel D3 receptor agonist, 8-OH-PBZI, and site-directed mutagenesis to identify key residues involved in D3 receptor signaling function. Our results show that trans-8-OH-PBZI, but not cis-8-OH-PBZI, elicit the D3 receptor tolerance and SRT properties. We show that while both agonists require a subset of residues in the orthosteric binding site of D3 receptors for activation of the receptor, the ability of the two isomers to differentially induce tolerance and SRT is mediated by interactions with specific residues in the sixth transmembrane helix and third extracellular loop of the D3 receptor. We also show that unlike cis-8-OH-PBZI, which is a partial agonist at the dopamine D2S receptor and full agonist at dopamine D2L receptor, trans-8-OH-PBZI is a full agonist at both D2S and D2L receptors. The different effect of the two isomers on D3 receptor signaling properties and D2S receptor activation correlated with differential effects of the isomers on agonist-induced mouse locomotor activity. The two isomers of 8-OH-PBZI represent novel pharmacological tools for in silico D3 and D2 receptor homology modeling and for determining the role of D3 receptor tolerance and SRT properties in signaling and behavior.
authors.affiliation: Department of Pharmacology, Physiology and Neuroscience, Rutgers-New Jersey Medical School, Newark, NJ 07103, USA.
authors.forename: Kokila
authors.initials: K
authors.lastname: Kota
authors.affiliation: Department of Pharmacology, Physiology and Neuroscience, Rutgers-New Jersey Medical School, Newark, NJ 07103, USA. Electronic address: kuzhikev@njms.rutgers.edu.
authors.forename: Eldo V
authors.initials: EV
authors.lastname: Kuzhikandathil
authors.affiliation: Department of Pharmacology, Physiology and Neuroscience, Rutgers-New Jersey Medical School, Newark, NJ 07103, USA.
authors.forename: Milad
authors.initials: M
authors.lastname: Afrasiabi
authors.affiliation: Department of Pharmaceutical Sciences, Southern Illinois University Edwardsville, Edwardsville, IL 62026, USA.
authors.forename: Brett
authors.initials: B
authors.lastname: Lacy
authors.affiliation: Department of Pharmaceutical Sciences, Southern Illinois University Edwardsville, Edwardsville, IL 62026, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Kontoyianni
authors.affiliation: Department of Pharmaceutical Sciences, Southern Illinois University Edwardsville, Edwardsville, IL 62026, USA.
authors.forename: A Michael
authors.initials: AM
authors.lastname: Crider
authors.affiliation: China Central Place, Johnson & Johnson, Chaoyang District, Beijing 10025, PR China.
authors.forename: Daniel
authors.initials: D
authors.lastname: Song
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D018491:Dopamine Agonists / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000737:chemistry / Q000494:pharmacology; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009043:Motor Activity / Q000187:drug effects; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D050637:Receptors, Dopamine D3 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013237:Stereoisomerism; D013764:Tetrahydronaphthalenes / Q000494:pharmacology
chemical_list: C111033:8-hydroxy-3-(n-propyl)-1,2,3a,4,5,9b-hexahydro-1H-benz(e)indole; C493593:DRD3 protein, human; D018491:Dopamine Agonists; D007211:Indoles; D050637:Receptors, Dopamine D3; D011994:Recombinant Proteins; D013764:Tetrahydronaphthalenes; C031349:7-hydroxy-2-N,N-dipropylaminotetralin
keywords: Adenylate cyclase; Desensitization; Dopamine receptor; Locomotor behavior; MAPK; PBZI; Potassium channel; Tolerance