DOPAMINE TRANSPORTER-- CLONING, CHROMOSOMAL LOCALIZATION AND GENE STUDIES

Project: Research project

Project Details

Description

The dopamine transporter/cocaine receptor (DAT) is the site at which
cocaine exerts rewarding/reinforcing effects. Cloning of the rat DAT
cDNA by Addiction Research Center molecular neurobiologists during the
preceding FY provided an opportunity to study the structure, genetics,
and expression of the human DATs and their genes and to seek species
differences in structure, function, or interaction with cocaine.
Polymorphic markers for the human gene would allow assessments of
possible contributions of population variants at the human DAT gene locus
to interindividual differences in vulnerability to substance abuse.
Studies of the murine DAT gene could facilitate work in transgenic mice.

cDNA libraries from human substantia nigra and brain stem, and libraries
constructed from human genomic DNA and mouse embryonic stem cell genomic
DNA yielded human and murine cDNAs and genomic clones; the human DAT is
94% identical to the rat sequence. It contains 620 amino acids that can
be arrayed in 12 hydrophobic, putative transmembrane domains with three
potential sites for N-linked glycosylation. The human DAT gene lies on
the telomeric region of chromosome 5pl5.3. Restriction Fragment Length
Polymorphisms (RFLPs) and Variable Number Tandem Repeat (VNTR) genetic
markers for the human DAT gene were identified along with
racially-dimorphic population distributions of the RFLP marker. Studies
of both markers in the same individuals reveal no detectable linkage
disequibrilium. DNA from individuals whose drug use histories were
characterized at the ARC was examined to seek association between
substance use and these 3' and 5' DAT gene markers. The VNTR and Taq I
RFLP were examined in more than 170 unrelated individuals with
well-characterized histories of lifetime substance use. These same
individuals show substantial allelic association with markers at the 3'
and 5' ends of the dopamine D2 receptor gene. However, there was no
association between either DAT gene marker and substance abuse. Human
and
murine DAT genomic clones reveal intron/exon boundaries at several sites
conserved with respect to the GABA transporter gene.
StatusNot started

Funding

  • National Institute on Drug Abuse

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