title: Rab 11 regulates constitutive dopamine transporter trafficking and function in N2A neuroblastoma cells.
abstract: The dopamine transporter (DAT) is a crucial regulator of dopaminergic neurotransmission which undergoes constitutive and substrate-mediated trafficking to and from the membrane. Although, considerable research has been done to elucidate the regulation of substrate-stimulated DAT trafficking, less is known about which trafficking proteins are involved in constitutive DAT trafficking. Rab proteins are GTPases known to regulate the trafficking of proteins to and from specific endocytic compartments. Rabs 8 and 11, in particular, are involved in trafficking proteins from intracellular compartments to the plasma membrane. In this study, we sought to determine whether Rabs 8 and 11 would modulate DAT activity and trafficking in N2A neuroblastoma cells. We used Rab mutations known to confer constitutively active or dominant negative activity of these proteins to investigate the role of Rab activity in constitutive DAT trafficking and function. We found that constitutively active Rab 11 upregulates DAT function and surface expression while neither the constitutively active nor the dominant negative mutant of Rab 8 had any effect on DA uptake. Furthermore, immunofluorescence experiments revealed that dominant negative Rab 11 overexpression results in decreased surface DAT indicating a necessary function of Rab 11 in DAT trafficking to the plasma membrane. These data show for the first time a functional role of Rab proteins in the constitutive recycling of DAT to the plasma membrane.
authors.affiliation: University of Michigan Medical School, Department of Pharmacology, Ann Arbor, MI 48109, USA. furmanc@umich.edu
authors.forename: Cheryse A
authors.initials: CA
authors.lastname: Furman
authors.forename: Charles B
authors.initials: CB
authors.lastname: Lo
authors.forename: Stephanie
authors.initials: S
authors.lastname: Stokes
authors.forename: Jose A
authors.initials: JA
authors.lastname: Esteban
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Gnegy
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D051379:Mice; D009154:Mutation; D021381:Protein Transport; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000502:physiology; D014162:Transfection; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*; D000099193:rab11 GTP-Binding Proteins
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D049452:Green Fluorescent Proteins; D011993:Recombinant Fusion Proteins; D020691:rab GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins; C530052:Rab8a protein, rat