title: Regulation of serotonin 1B receptor by glycogen synthase kinase-3.
abstract: In response to 5-hydroxytryptamine (5-HT), the type 1 serotonin receptors (5-HT1Rs) preferentially couple to the inhibitory G protein and elicit many physiological and behavioral processes. However, their regulation by intracellular protein kinases has not been fully investigated. In this study, we identified that glycogen synthase kinase-3 (GSK3) differentially regulates 5-HT1Rs. In receptor-expressing cells and brain slices, activation of both 5-HT1AR and 5-HT1BR reduced forskolin-stimulated cAMP production, but only the effect of 5-HT1BR was abolished by selective GSK3 inhibitors, deletion of GSK3beta by RNAi, or overexpression of impaired GSK3beta mutants (R96A and K85,86A). A consensus GSK3 phosphorylation sequence was identified between the serine-154 and threonine-158 in the second intracellular loop of 5-HT1BR. Mutation of either serine-154 or threonine-158 to alanine significantly reduced response of 5-HT1BR to 5-HT. Active GSK3beta interacted with resting 5-HT1BR to form a protein complex. The interaction was enhanced by receptor activation, abolished by GSK3 inhibitors, and dependent on the phosphorylation state of serine-154. In addition, regulation of 5-HT1BR by GSK3 changed the dynamics of agonist-induced cell surface receptor internalization, in which lack of phosphorylation at Ser154 resulted in sustained reduction of 5-HT1BR at the cell surface. Although the physiological consequences of selective regulation of 5-HT1BR by GSK3 remain to be identified, findings in this study reveal a new function of GSK3 as a protein kinase that is able to selectively regulate G protein-coupled receptors.
authors.affiliation: Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
authors.forename: Ligong
authors.initials: L
authors.lastname: Chen
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Salinas
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Li
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D001552:Benzazepines / Q000494:pharmacology; D016466:CHO Cells; D002460:Cell Line; D002772:Cholera Toxin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008301:Maleimides / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D010069:Oxadiazoles / Q000494:pharmacology; D010091:Oximes / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D010881:Piperidones / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011687:Purines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D044302:Receptor, Serotonin, 5-HT1B / Q000235:genetics / Q000502:physiology*; D000077546:Roscovitine; D012701:Serotonin / Q000494:pharmacology; D013141:Spiro Compounds / Q000494:pharmacology
chemical_list: C483321:6-bromoindirubin-3'-oxime; D001549:Benzamides; D001552:Benzazepines; D007211:Indoles; D008301:Maleimides; C108531:N-(3-(2-dimethylamino)ethoxy-4-methoxyphenyl)-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)-(1,1'-biphenyl)-4-carboxamide; D010069:Oxadiazoles; D010091:Oximes; D010880:Piperidines; D010881:Piperidones; D047428:Protein Kinase Inhibitors; D011687:Purines; D011725:Pyridines; D044302:Receptor, Serotonin, 5-HT1B; C417521:SB 216763; C108518:SB 22489G; D013141:Spiro Compounds; C119620:kenpaullone; D000077546:Roscovitine; D005576:Colforsin; C075631:anpirtoline; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D002772:Cholera Toxin; D000242:Cyclic AMP; D038362:Glycogen Synthase Kinase 3