title: Diverse arrestin-recruiting and endocytic profiles of tricyclic antipsychotics acting as direct α2Aadrenergic receptor ligands.
abstract: The therapeutic mechanism of action underlying many psychopharmacological agents remains poorly understood, due largely to the extreme molecular promiscuity exhibited by these agents with respect to potential central nervous system targets. Agents of the tricyclic chemical class, including both antidepressants and antipsychotics, exhibit a particularly high degree of molecular promiscuity; therefore, any clarification of how these agents interact with specific central nervous system targets is of great potential significance to the field. Here, we present evidence demonstrating that tricyclic antipsychotics appear to segregate into three distinct groups based upon their molecular interactions with the centrally-important α2Aadrenergic receptor (AR). Specifically, while the α2AAR binds all antipsychotics tested with similar affinities, and none of the agents are able to induce classical heterotrimeric G protein-mediated α2AAR signaling, significant differences are observed with respect to arrestin3 recruitment and receptor endocytosis. All antipsychotics tested induce arrestin3 recruitment to the α2AAR, but with differing strengths. Both chlorpromazine and clozapine drive significant α2AAR endocytosis, but via differing clathrin-dependent and lipid raft-dependent pathways, while fluphenazine does not drive a robust response. Intriguingly, in silico molecular modeling suggests that each of the three exhibits unique characteristics in interacting with the α2AAR ligand-binding pocket. In addition to establishing these three antipsychotics as novel arrestin-biased ligands at the α2AAR, our findings provide key insights into the molecular actions of these clinically-important agents.
authors.affiliation: Department of Cell, Molecular and Developmental Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA; Department of Biology and Chemistry, Morehead State University, Morehead, KY 40351, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Cottingham
authors.affiliation: Department of Cell, Molecular and Developmental Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Pulin
authors.initials: P
authors.lastname: Che
authors.affiliation: Southern Research Institute, Birmingham, AL 35205, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Cell, Molecular and Developmental Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Raymond X
authors.initials: RX
authors.lastname: Wang
authors.affiliation: Department of Cell, Molecular and Developmental Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Percival
authors.affiliation: Department of Cell, Molecular and Developmental Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Tana
authors.initials: T
authors.lastname: Birky
authors.affiliation: Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Lufang
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Jiao
authors.affiliation: Department of Cell, Molecular and Developmental Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA. Electronic address: qinwang@uab.edu.
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology*; D051242:Caveolin 1 / Q000378:metabolism; D002746:Chlorpromazine / Q000494:pharmacology; D003024:Clozapine / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects* / Q000502:physiology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005476:Fluphenazine / Q000494:pharmacology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D062105:Molecular Docking Simulation; D009638:Norepinephrine / Q000494:pharmacology; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism*; D000071559:beta-Arrestin 1 / Q000235:genetics / Q000378:metabolism*; D000071560:beta-Arrestin 2 / Q000235:genetics / Q000378:metabolism*
chemical_list: D014150:Antipsychotic Agents; D051242:Caveolin 1; D018341:Receptors, Adrenergic, alpha-2; D000071559:beta-Arrestin 1; D000071560:beta-Arrestin 2; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000242:Cyclic AMP; D003024:Clozapine; D005476:Fluphenazine; D002746:Chlorpromazine; D009638:Norepinephrine
keywords: Antipsychotic; Arrestin; Biased agonism; Endocytosis; Lipid raft; α(2) adrenergic receptor