Dopamine transporter mutants with cocaine resistance and normal dopamine uptake provide targets for cocaine antagonism.
Cocaine's blockade of dopamine reuptake by brain dopamine transporters (DAT) is a central feature of current understanding of cocaine reward and addiction. Empirical screening of small-molecule chemical libraries has thus far failed to provide successful cocaine blockers that allow dopamine reuptake in the presence of cocaine and provide cocaine "antagonism". We have approached this problem by assessing expression, dopamine uptake, and cocaine analog affinities of 56 DAT mutants in residues located in or near transmembrane domains likely to play significant roles in cocaine recognition and dopamine uptake. A phenylalanine-to-alanine mutant in putative DAT transmembrane domain 3, F154A, retains normal dopamine uptake, lowers cocaine affinity 10-fold, and reduces cocaine stereospecificity. Such mutants provide windows into DAT structures that could serve as targets for selective cocaine blockers and document how combined strategies of mutagenesis and small molecule screening may improve our abilities to identify and design compounds with such selective properties.
Lin
Zhicheng
Z
Molecular Neurobiology Branch, National Institute on Drug Abuse-Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA.
Uhl
George R
GR
D019943:Amino Acid Substitution; D000818:Animals; D001667:Binding, Competitive; D019556:COS Cells; D002522:Chlorocebus aethiops; D003042:Cocaine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology; D004347:Drug Interactions; D004351:Drug Resistance; D008454:Mazindol / Q000494:pharmacology; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D020409:Molecular Motor Proteins; D009154:Mutation; D009419:Nerve Tissue Proteins; D014162:Transfection; D014316:Tritium
D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D020409:Molecular Motor Proteins; D009419:Nerve Tissue Proteins; D014316:Tritium; C021279:(1R-(exo,exo))-3-(4-fluorophenyl)-8-methyl-8- azabicyclo(3.2.1)octane-2-carboxylic acid, methyl ester; D008454:Mazindol; D003042:Cocaine; D004298:Dopamine