# Dopamine Transporter Cell Surface Dynamics

> **NIH NIH R01** · UNIV OF MASSACHUSETTS MED SCH WORCESTER · 2020 · $442,642

## Abstract

Dopamine (DA) is a major neurotransmitter with diverse physiological impact, and is required for movement,
working memory, and reward. Following evoked release, DA extracellular half-life is determined by presynaptic
reuptake, mediated by the SLC6 plasma membrane DA transporter (DAT). DAT is the primary target for
addictive and therapeutic psychostimulants, such as amphetamine, cocaine and methylphenidate (Ritalin),
which potently inhibit DA uptake, sustain DA signaling and impact DA-dependent behaviors. DAT coding
variants are implicated in a variety of neuropsychiatric disorders, and transgenic mouse studies clearly
demonstrate that DAergic signaling and behaviors, as well as psychostimulant efficacy, are highly sensitive to
the level of DAT expression. DAT is not static at the plasma membrane, but is subject to robust constitutive
endocytic recycling. Moreover, direct protein kinase C (PKC) activation rapidly accelerates DAT internalization
and decreases DAT surface availability and function. Efforts over nearly two decades have elucidated many of
the mechanisms underlying basal and PKC-regulated DAT trafficking. However, it remains unclear how DAT is
regulated in bona fide presynaptic DA terminals, whether DAT regulation is region-dependent, and whether
DAT trafficking impacts DA signaling. Moreover, it is unknown whether DAT trafficking mechanisms identified
in cell line studies are physiologically relevant. The major goals of the proposed studies are to determine the
presynaptic mechanisms that regulate DAT surface expression, and test whether DAT trafficking has
physiological impact on DA release and clearance. Specifically, we aim to test 1) whether presynaptic Gq-coupled receptor activation impacts DAT surface expression and function in a region-dependent manner, 2)
whether retrograde signaling within the striatum regulates presynaptic DAT surface expression and function,
and 3) whether DAT trafficking dysfunction impacts DA signaling. These hypotheses stem from strong
preliminary data that demonstrate region-specific, Gq-mediated, biphasic DAT trafficking in striatal DAergic
terminals, and putative roles for the Gq-coupled M5 and Gi-couple NOPR receptors in presynaptic DAT
trafficking. These provocative findings suggest that multiple mechanisms converge on DAT within the striatum
to regulate DAT surface availability and function. To pursue this investigative line, we will leverage a variety of
state-of-the-art mouse genetic tools, including a newly developed viral approach to conditionally and inducibly
achieve shRNA-mediated gene knockdown in DA neurons, as well as chemogenetic and optogenetic
strategies. Ex vivo striatal slice studies will measure changes in DAT surface expression in response to
presynaptic receptor activation, and fast-scan cyclic voltammetry will measure DA release and DAT-mediated
clearance, in parallel. Conditional transgene expression, gene ablation and shRNA-mediated knockdown
strategies will be used to define t...

## Key facts

- **NIH application ID:** 9902390
- **Project number:** 5R01DA035224-08
- **Recipient organization:** UNIV OF MASSACHUSETTS MED SCH WORCESTER
- **Principal Investigator:** Haley E Melikian
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $442,642
- **Award type:** 5
- **Project period:** 2013-05-01 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9902390

## Citation

> US National Institutes of Health, RePORTER application 9902390, Dopamine Transporter Cell Surface Dynamics (5R01DA035224-08). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9902390. Licensed CC0.

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