Phosphorylation of the Amino Terminus of the Dopamine Transporter: Regulatory Mechanisms and Implications for Amphetamine Action

Abstract

Amphetamines (AMPHs) are potent psychostimulants that are widely used and abused, with profound medical and societal impact. Their actions at dopaminergic neurons are thought to mediate their therapeutic efficacy as well as their liability for abuse and dependence. AMPHs target the dopamine transporter (DAT), the plasmalemmal membrane protein that mediates the inactivation of released dopamine (DA) through its reuptake. AMPHs act as substrates for DAT and are known to cause mobilization of dopamine (DA) to the cell exterior via DAT-mediated reverse transport (efflux). It has become increasingly evident that the mechanisms that regulate AMPH-induced DA efflux are distinct from those that regulate DA uptake. Central to these mechanisms is the phosphorylation of the DAT amino (N)-terminus, which has been repeatedly demonstrated to facilitate DAT-mediated DA efflux, without impacting other aspects of DAT physiology. This review aims to summarize the current status of knowledge regarding DAT N-terminal phosphorylation and its regulation by protein modulators and the membrane microenvironment. A better understanding of these mechanisms may lead to the identification of novel therapeutic approaches that interfere selectively with the pharmacological effects of AMPHs without altering the physiological function of DAT.

Acute Food Deprivation Decreases the Expression of Methamphetamine-Induced Locomotor Sensitization in Rats

“…The DAT is a plasma membrane transport protein that belongs to the Na+/Cl-dependent transporter gene family and is responsible for regulating the concentration of extracellular DA (Giros & Caron, 1993;Vaughan & Foster, 2013). Second, AMPH increases DA release, depleting vesicular DA stores and promoting DA release through reversing the DAT function (Fleckenstein, Volz, Riddle, Gibb, & Hanson, 2007;Karam & Javitch, 2018;Sulzer, 2011). AMPH-like drugs not only inhibit DA uptake and increase DA efflux mediated through the DAT but also decrease DAT surface expression (Fleckenstein, Metzger, Wilkins, Gibb, & Hanson,1997;Kahlig et al, 2006;Karam & Javitch, 2018;Saunders et al, 2000).…”

“…Second, AMPH increases DA release, depleting vesicular DA stores and promoting DA release through reversing the DAT function (Fleckenstein, Volz, Riddle, Gibb, & Hanson, 2007;Karam & Javitch, 2018;Sulzer, 2011). AMPH-like drugs not only inhibit DA uptake and increase DA efflux mediated through the DAT but also decrease DAT surface expression (Fleckenstein, Metzger, Wilkins, Gibb, & Hanson,1997;Kahlig et al, 2006;Karam & Javitch, 2018;Saunders et al, 2000). These effects of AMPH-like drugs produce an increase in DA neurotransmission (Wheeler et al, 2015).…”

“…Akt is a downstream component of the insulin signaling pathway through activation of PI3K and is involved in the regulation of DA signaling (Beaulieu, Gainetdinov, & Caron, 2007). Akt is reported to play a key role in the surface expression of the DAT (García et al, 2005, Speed et al, 2011, which is required for psychostimulants such as AMPH and METH to enhance DA neurotransmission (Karam & Javitch, 2018;Khoshbouei et al, 2004;McFadden, Vieira-Brock, Hanson, & Fleckenstein 2015). AMPH and its N-methylated derivative METH are psychostimulants that share a common molecular structure (Melega, Williams, Schmitz, Distefano, & Cho, 1995).…”

Regulation of Glutamate, GABA and Dopamine Transporter Uptake, Surface Mobility and Expression

“…The N-terminus of the DAT protein is subject to phosphorylation and ubiquitination ( Karam and Javitch, 2018 ). Although five serine residues at positions 2, 4, 7, 12, 13 have been identified as targets for phosphorylation by PKC, the only verified phosphorylation site is Ser7 ( Moritz et al, 2013 ).…”

PINK1 Regulates Dopamine and Lipids at Mitochondria to Maintain Synapses and Neuronal Function

“…Next we fractionated hDAN lysates by density and used marker proteins to identify the soluble fractions (8)(9)(10)(11)(12)(13)(14) and the cholesterol-rich floating fractions (3-7) marked by flotillin ( Figure 4B). We assessed the distribution of several membrane-bound and cytosolic Since the dopamine transporter DAT is known to be negatively regulated by its phosphorylation in cholesterol rich lipid membrane rafts 74 reviewed in 75 , we then assessed the distribution of phosphorylated DAT and total DAT. PINK1 KO leads to more phosphorylated DAT in less soluble fractions ( Figure 4D), which leads to increased DAT internalization.…”