title: Regulation of human organic cation transporter hOCT2 by PKA, PI3K, and calmodulin-dependent kinases.
abstract: Properties and regulation of the human organic cation (OC) transporter type 2 (hOCT2) expressed in HEK-293 cells were extensively characterized using the fluorescent OC 4-[4-(dimethylamino)styryl]-N-methylpyridinium (ASP(+)). ASP(+) uptake was electrogenic and inhibited by TPA(+) (EC(50) = 2.7 microM), tetraethylammonium (EC(50) = 35 microM), cimetidine (EC(50) = 36 microM), or quinine (EC(50) = 6.7 microM). Stimulation with carbachol or ATP decreased initial uptake by 44 +/- 3 (n = 14) and 34 +/- 4% (n = 21), respectively, independently of PKC but dependent on phosphatidylinositol 3-kinase (PI3K). PKA stimulation decreased uptake by 18 +/- 4% (n = 40). Inhibition of calmodulin (CaM), Ca(2+)/CaM-dependent kinase II, or myosin light chain kinase decreased uptake by 63 +/- 2 (n = 15), 40 +/- 4 (n = 30), and 31 +/- 4% (n = 16), respectively. Inhibition of CaM resulted in a significant change in the EC(50) value for the inhibition of ASP(+) uptake by tetraethylammonium. In conclusion, we demonstrate that the hOCT2 is inhibited by PI3K and PKA and activated by a CaM-dependent signaling pathway, probably via a change in substrate affinity.
authors.affiliation: Medizinische Klinik und Poliklinik D, Experimentelle Nephrologie, and Klinik und Poliklinik für Kinderheilkunde, Universitätsklinikum Münster, D-48149 Münster, Germany.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Cetinkaya
authors.forename: Giuliano
authors.initials: G
authors.lastname: Ciarimboli
authors.forename: Gülay
authors.initials: G
authors.lastname: Yalçinkaya
authors.forename: Thomas
authors.initials: T
authors.lastname: Mehrens
authors.forename: Ana
authors.initials: A
authors.lastname: Velic
authors.forename: Jochen R
authors.initials: JR
authors.lastname: Hirsch
authors.forename: Valentin
authors.initials: V
authors.lastname: Gorboulev
authors.forename: Hermann
authors.initials: H
authors.lastname: Koepsell
authors.forename: Eberhard
authors.initials: E
authors.lastname: Schlatter
mesh_terms: D001667:Binding, Competitive; D002118:Calcium / Q000502:physiology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology*; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D004563:Electrochemistry; D004789:Enzyme Activation / Q000502:physiology; D006801:Humans; D027701:Organic Cation Transport Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000075102:Organic Cation Transporter 2; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D011493:Protein Kinase C / Q000378:metabolism; D011726:Pyridinium Compounds / Q000493:pharmacokinetics; D013379:Substrate Specificity
chemical_list: C032315:4-(4-dimethylaminostyryl)-1-methylpyridinium; D027701:Organic Cation Transport Proteins; D000075102:Organic Cation Transporter 2; D011726:Pyridinium Compounds; C491013:SLC22A2 protein, human; D019869:Phosphatidylinositol 3-Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium