title: Protein Kinases Alter the Allosteric Modulation of the Serotonin Transporter In Vivo and In Vitro.
abstract: Studies using S- and R-enantiomers of the SSRI citalopram have shown that R-citalopram exerts an antagonistic effect on the efficacy of the antidepressant S-citalopram (escitalopram) through an interaction at an allosteric modulator site on the serotonin transporter (SERT). Here, we show that protein kinase signaling systems are involved in the allosteric modulation of the SERT in vivo and in vitro.
  
  
  
  We assessed the effects of nonspecific protein kinase inhibitor staurosporine in the action of escitalopram and/or R-citalopram using electrophysiological and behavioral assays in rats and cell surface SERT expression measures in serotoninergic cells.
  
  
  
  Acute administration of R-citalopram counteracted the escitalopram-induced suppression of the serotonin (5-HT) neuronal firing activity and increase of the head twitches number following L-5-hydroxytryptophan injection. Importantly, these counteracting effects of R-citalopram were abolished by prior systemic administration of staurosporine. Interestingly, the preventing effect of staurosporine on 5-HT neuronal firing activity was abolished by direct activation of protein kinase C with phorbol 12-myristate 13-acetate. Finally, in vitro, quantification of the amount of cell surface-expressed SERT molecules revealed that R-citalopram prevented escitalopram-induced SERT internalization that was completely altered by staurosporine.
  
  
  
  Taken together, these results highlight for the first time an involvement of protein kinases in the allosteric modulation of SERT function.
authors.affiliation: Univ Lyon, Université Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, 69500 Bron, France.|Department of Integrative Neurophysiology, CNCR, Vrije Universiteit, Amsterdam, The Netherlands.
authors.forename: Ouissame
authors.initials: O
authors.lastname: Mnie-Filali
authors.affiliation: Biochemical Laboratory, Central Institute of Mental Health, Mannheim, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Lau
authors.affiliation: Biochemical Laboratory, Central Institute of Mental Health, Mannheim, Germany.
authors.forename: Friederike
authors.initials: F
authors.lastname: Matthaeus
authors.affiliation: Univ Lyon, Université Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, 69500 Bron, France.
authors.forename: Erika
authors.initials: E
authors.lastname: Abrial
authors.affiliation: Univ Lyon, Université Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, 69500 Bron, France.
authors.forename: Sarah
authors.initials: S
authors.lastname: Delcourte
authors.affiliation: Institute of Mental Health Research, University of Ottawa, Ottawa, ON, Canada.
authors.forename: Mostafa
authors.initials: M
authors.lastname: El Mansari
authors.affiliation: Neuropharmacology, Lundbeck Research USA, Paramus, NJ, USA.
authors.forename: Alan
authors.initials: A
authors.lastname: Pershon
authors.affiliation: Biochemical Laboratory, Central Institute of Mental Health, Mannheim, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Schloss
authors.affiliation: Neuropharmacology, Lundbeck Research USA, Paramus, NJ, USA.
authors.forename: Connie
authors.initials: C
authors.lastname: Sánchez
authors.affiliation: Univ Lyon, Université Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, 69500 Bron, France.
authors.forename: Nasser
authors.initials: N
authors.lastname: Haddjeri
mesh_terms: D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002227:Carbazoles / Q000494:pharmacology; D015283:Citalopram / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000166:cytology; D026121:Indole Alkaloids / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000187:drug effects*; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism*; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology; D013237:Stereoisomerism; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D006916:5-Hydroxytryptophan; D002227:Carbazoles; D015283:Citalopram; D004791:Enzyme Inhibitors; D026121:Indole Alkaloids; D011494:Protein Kinases; D012701:Serotonin; D050486:Serotonin Plasma Membrane Transport Proteins; D017367:Selective Serotonin Reuptake Inhibitors; D013755:Tetradecanoylphorbol Acetate; C020922:4-O-methyl-12-O-tetradecanoylphorbol 13-acetate; C049985:staurosporine aglycone
keywords: 5-HT transporter; Allosteric modulation; Escitalopram; Protein Kinases; R-citalopram; Staurosporine