TY - JOUR T1 - Colocalization and Regulated Physical Association of Presynaptic Serotonin Transporters with A3 Adenosine Receptors JF - Molecular Pharmacology JO - Mol Pharmacol DO - 10.1124/mol.111.071399 SP - mol.111.071399 AU - Chongbin Zhu AU - Kathryn M. Lindler AU - Nicholas G. Campbell AU - James S. Sutcliffe AU - William A. Hewlett AU - Randy D. Blakely Y1 - 2011/01/01 UR - http://molpharm.aspetjournals.org/content/early/2011/06/24/mol.111.071399.abstract N2 - Activation of A3 adenosine receptors (A3ARs) rapidly enhances the activity of antidepressant-sensitive serotonin (5-HT) transporters (SERTs) in vitro, ex vivo and in vivo. A3AR agonist stimulation of SERT activity is lost in A3AR knockout mice. A3AR-stimulated SERT activity is mediated by protein kinase G1 (PKGI)- and p38 mitogen activated protein kinase (MAPK)-linked pathways that support, respectively, enhanced SERT surface expression and catalytic activation. The mechanisms by which A3ARs target SERTs among other potential effectors is unknown. Here we present evidence that A3ARs are co-expressed with SERT in midbrain serotonergic neurons and form a physical complex in A3AR/hSERT co-transfected cells. Treatment of A3AR/SERT co-transfected Chinese Hamster Ovary (CHO) cells with the A3AR agonist IB-MECA (1 μM, 10 min), conditions previously reported to increase SERT surface expression and 5-HT uptake activity, enhanced the abundance of A3AR/SERT complexes in a PKGI-dependent manner. Co-transfection of SERT with L90V-A3AR, a hyperfunctional coding variant identified in subjects with autism spectrum disorder (ASD), resulted in a prolonged recovery of receptor/transporter complexes following A3AR activation. As PKGI and nitric oxide synthetase (NOS) are required for A3AR stimulation of SERT activity, and both proteins PKGI and NOS form complexes with SERT, our findings suggest a mechanism by which signaling pathways coordinating A3AR signaling to SERT can be spatially restricted and regulated, as well as compromised by neuropsychiatric disorders. ER -