title: Amphetamine induces a calcium/calmodulin-dependent protein kinase II-dependent reduction in norepinephrine transporter surface expression linked to changes in syntaxin 1A/transporter complexes.
abstract: Norepinephrine (NE) transporters (NETs) are high-affinity transport proteins that mediate the synaptic clearance of NE after vesicular release. NETs represent a major therapeutic target for antidepressants and are targets of multiple psychostimulants including amphetamine (AMPH) and cocaine. Recently, we demonstrated that syntaxin 1A (SYN1A) regulates NET surface expression and, through binding to the transporter's NH(2) terminus, regulates transporter catalytic function. AMPH induces NE efflux and may also regulate transporter trafficking. We monitored NET distribution and function in catecholaminergic cell lines (CAD) stably transfected with either full-length human NET (CAD-hNET) or with an hNET N-terminal deletion (CAD-hNETDelta(28-47) cells). In hNET-CAD cells, AMPH causes a slow and small reduction of surface hNET with a modest increase in hNET/SYN1A associations at the plasma membrane. In contrast, in CAD-hNETDelta(28-47) cells, AMPH induces a rapid and substantial reduction in surface hNETDelta(28-47) accompanied by a large increase in plasma membrane hNETDelta(28-47)/SYN1A complexes. We also found that AMPH in CAD-hNETDelta(28-47) cells induces a robust increase in cytosolic Ca2+ and concomitant activation of calcium/calmodulin-dependent protein kinase II (CaMKII). Inhibition of either the increase in intracellular Ca2+ or CaMKII activity blocks AMPH-stimulated hNETDelta(28-47) trafficking and the formation of hNETDelta(28-47)/SYN1A complexes. Here, we demonstrate that AMPH stimulation of CAMKII stabilizes an hNET/SYN1A complex. This hNET/SYN1A complex rapidly redistributes, upon AMPH treatment, when mechanisms supported by the transporter's NH2 terminus are eliminated.
authors.affiliation: Department of Molecular Physiology and Biophysics, Center for Molecular Neuroscience, Vanderbilt University Medical Center, 465 21st Avenue South, 7124A Medical Research Building III, Nashville, TN 37232, USA.
authors.forename: Concetta
authors.initials: C
authors.lastname: Dipace
authors.forename: Uhna
authors.initials: U
authors.lastname: Sung
authors.forename: Francesca
authors.initials: F
authors.lastname: Binda
authors.forename: Randy D
authors.initials: RD
authors.lastname: Blakely
authors.forename: Aurelio
authors.initials: A
authors.lastname: Galli
mesh_terms: D000661:Amphetamine / Q000494:pharmacology*; D019921:Biotinylation; D002118:Calcium / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D006801:Humans; D007700:Kinetics; D050484:Norepinephrine Plasma Membrane Transport Proteins / Q000235:genetics*; D050827:Syntaxin 1 / Q000378:metabolism*
chemical_list: D050484:Norepinephrine Plasma Membrane Transport Proteins; D050827:Syntaxin 1; D000661:Amphetamine; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium