title: Amphetamine-induced decreases in dopamine transporter surface expression are protein kinase C-independent.
abstract: Amphetamine (AMPH) is a potent dopamine (DA) transporter (DAT) inhibitor that markedly increases extracellular DA levels. In addition to its actions as a DAT antagonist, acute AMPH exposure induces DAT losses from the plasma membrane, implicating transporter-specific membrane trafficking in amphetamine's actions. Despite reports that AMPH modulates DAT surface expression, the trafficking mechanisms leading to this effect are currently not defined. We recently reported that DAT residues 587-596 play an integral role in constitutive and protein kinase C (PKC)-accelerated DAT internalization. In the current study, we tested whether the structural determinants required for PKC-stimulated DAT internalization are necessary for AMPH-induced DAT sequestration. Acute amphetamine exposure increased DAT endocytic rates, but DAT carboxy terminal residues 587-590, which are required for PKC-stimulated internalization, were not required for AMPH-accelerated DAT endocytosis. AMPH decreased DAT endocytic recycling, but did not modulate transferrin receptor recycling, suggesting that AMPH does not globally diminish endocytic recycling. Finally, treatment with a PKC inhibitor demonstrated that AMPH-induced DAT losses from the plasma membrane were not dependent upon PKC activity. These results suggest that the mechanisms responsible for AMPH-mediated DAT internalization are independent from those governing PKC-sensitive DAT endocytosis.
authors.affiliation: Brudnick Neuropsychiatric Research Institute, Department of Psychiatry, University of Massachusetts Medical School, 303 Belmont Street, Worcester, MA 01604, USA.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Boudanova
authors.forename: Deanna M
authors.initials: DM
authors.lastname: Navaroli
authors.forename: Haley E
authors.initials: HE
authors.lastname: Melikian
mesh_terms: D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D004298:Dopamine / Q000378:metabolism; D050483:Dopamine Plasma Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D004705:Endocytosis / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D016296:Mutagenesis; D016716:PC12 Cells / Q000187:drug effects; D011493:Protein Kinase C / Q000502:physiology*; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D013997:Time Factors; D014162:Transfection
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors; D004791:Enzyme Inhibitors; D000661:Amphetamine; D011493:Protein Kinase C; D004298:Dopamine