Transient Suppression of Dopamine Transporter Palmitoylation by Methamphetamine: Implications for Transport Regulation

Abstract

The dopamine transporter (DAT) exerts temporal and spatial control over dopaminergic neurotransmission through reuptake of extracellular dopamine (DA). The functional capacity of DAT is under the control of signaling inputs and post-translational modifications that confer acute presynaptic regulation of reuptake in response to physiological needs, and dysregulation of these processes may contribute to DA imbalances in mood disorders and drug addiction. A key modification of DAT is palmitoylation, a lipid adduction that enhances transport velocity, is suppressed by protein kinase C, and opposes protein kinase C-mediated down-regulation. Here we now show in rat striatum and heterologous cells that transporter palmitoylation is also linked to methamphetamine (METH), undergoing rapid and transient reductions in response to the drug. The time course and other characteristics of palmitoylation reduction parallel those of METH-induced transport down-regulation, and a palmitoylation-deficient DAT mutant shows enhanced down-regulation to METH, supporting a mechanistic link between reduction of the modification and reduced reuptake activity. Recovery rates differed, however, with palmitoylation returning to starting levels more rapidly than reuptake, indicating that down-regulation mechanisms remain engaged with transporters that have undergone repalmitoylation. These results support palmitoylation as a rapid response mechanism that modulates DAT entry into METH-induced down-regulation states and suggest a broader role for the modification in control of reuptake in additional physiological and pathophysiological conditions.