# Functional validation of a role for the candidate gene Ctr9 in psychostimulant action

> **NIH NIH R21** · NEW YORK STATE PSYCHIATRIC INSTITUTE DBA RESEARCH FOUNDATION FOR MENTAL HYGIENE, INC · 2022 · $199,875

## Abstract

The mechanisms that mediate substance abuse liability are incompletely understood and therapeutic
interventions for psychostimulant addiction remain largely ineffective. We conducted a genome-wide association
study in Drosophila and identified the gene Ctr9 to be significantly associated with the locomotor response to
amphetamine. Ctr9 is known to play a role in regulating gene expression as part of the Paf1C transcription
complex. It was also shown in one publication to interact with the dopamine transporter, the major molecular
target of psychostimulants. We have validated the role of Ctr9 in amphetamine-induced hyperactivity in flies;
dopamine neuron-specific knockdown of Ctr9 leads to a dramatic increase in the response to amphetamine and
methamphetamine, whereas its overexpression blunts the response. We have also shown that Ctr9 co-localizes
with dopamine transporter (DAT) outside of the nucleus in dopamine neurons in the adult fly brain. We now aim
to characterize the mechanisms underlying its effects on dopamine neurotransmission and methamphetamine-
induced behavior in Drosophila and to develop a genetic model to functionally validate the role of Ctr9 in
methamphetamine- and cocaine-induced hyperlocomotion in rats, which are uniquely suited to model traits that
mimic compulsive drug-seeking behavior in humans and will thus facilitate our long-term goal to investigate the
role of Ctr9 in addiction-like behavior. In pursuit of these goals, we propose the following specific aims:
(1) To elucidate the mechanisms by which Ctr9 modulates methamphetamine-induced locomotor activity
in flies. (a) We will use 2-photon imaging of a dopamine biosensor to determine the impact of Ctr9 knockdown
and overexpression on optogenetically-evoked and methamphetamine-induced dopamine release. (b) To
determine if the nuclear localization of Ctr9 is essential for its role in dopamine-mediated locomotor activity in
Drosophila, we will express a truncated Ctr9 protein that is blocked from translocating to the nucleus (Ctr9ΔSH2)
and test its impact on basal and methamphetamine-induced locomotion. (c) We will knock down the expression
of Ctr9 strictly during adulthood, and at different times during development, to determine if Ctr9 knockdown
interferes with early neurodevelopment to influence susceptibility to methamphetamine later in life or if it acts
acutely during adulthood to modulate methamphetamine-induced behavior.
(2) To establish a role for Ctr9 in the behavioral response to methamphetamine in rats and determine its
impact on dopamine neurotransmission and DAT function. We will (a) generate a conditional Ctr9 knockout
rat using a CRISPR/Cas9-mediated “Germline Gene Targeting” approach and (b) test the effects of deleting Ctr9
selectively in dopamine neurons on basal and methamphetamine- and cocaine-induced hyperactivity. (c) We
will test the impact of selective knockout of Ctr9 in dopamine neurons on DAT cell-surface localization, evoked dopamine release, ...

## Key facts

- **NIH application ID:** 10392183
- **Project number:** 1R21DA055441-01
- **Recipient organization:** NEW YORK STATE PSYCHIATRIC INSTITUTE DBA RESEARCH FOUNDATION FOR MENTAL HYGIENE, INC
- **Principal Investigator:** Jonathan A Javitch
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $199,875
- **Award type:** 1
- **Project period:** 2022-09-01 → 2024-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10392183

## Citation

> US National Institutes of Health, RePORTER application 10392183, Functional validation of a role for the candidate gene Ctr9 in psychostimulant action (1R21DA055441-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10392183. Licensed CC0.

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