title: A direct interaction of PSD-95 with 5-HT2A serotonin receptors regulates receptor trafficking and signal transduction.
abstract: The serotonin (5-hydroxytryptamine) 2A receptor (5-HT2A) is an important G protein-coupled receptor (GPCR) that mediates the effects of hallucinogens and is the target of a number of commonly prescribed medications including atypical antipsychotics, antidepressants, and anxiolytics. The 5-HT2A receptor possesses a canonical Type I PDZ-binding domain (X-Ser/Thr-X-Phi) at the carboxyl terminus and has been predicted, but never demonstrated, to interact with PDZ domain-containing proteins. We discovered that PSD-95, a prototypic PDZ domain-containing protein, directly associates with the 5-HT2A receptor and regulates 5-HT2A receptor-mediated signaling and trafficking in HEK-293 cells. Co-immunoprecipitation studies revealed that the native 5-HT2A receptor, but not a mutant lacking the PDZ-binding domain, interacted directly with PSD-95. The association with PSD-95 enhanced 5-HT2A receptor-mediated signal transduction, a novel action of PSD-95 on GPCRs. The augmentation of 5-HT2A receptor signaling by PSD-95 was not accompanied by alteration in the kinetics of 5-HT2A receptor desensitization but was associated with the inhibition of agonist-induced 5-HT2A receptor internalization. Additional studies demonstrated that 5-HT2A receptor and PSD-95 were co-localized in clusters on the cell surface of HEK-293 cells. Taken together, the present work elucidates novel roles for PSD-95 in regulating the functional activity and intracellular trafficking of 5-HT2A receptors and possibly other GPCRs.
authors.affiliation: Department of Biochemistry, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
authors.forename: Zongqi
authors.initials: Z
authors.lastname: Xia
authors.forename: John A
authors.initials: JA
authors.lastname: Gray
authors.forename: Beth A
authors.initials: BA
authors.lastname: Compton-Toth
authors.forename: Bryan L
authors.initials: BL
authors.lastname: Roth
mesh_terms: D020816:Amino Acid Motifs; D002460:Cell Line; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D006801:Humans; D006868:Hydrolysis; D008856:Microscopy, Fluorescence; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection
chemical_list: D018076:DNA, Complementary; D009419:Nerve Tissue Proteins; D010716:Phosphatidylinositols; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin; C033652:postsynaptic density proteins