Functional Genomic Analysis of Amphetamine Sensitivity in Drosophila

Caline S Karam,David Goldman,Sergey Kalachikov,Brenna L Williams,Irina Morozova,Yuchao Zhang,Qiaoping Yuan,Colin A Hodgkinson,Rony Panarsky,Jonathan A Javitch

doi:10.3389/fpsyt.2022.831597

Abstract

Abuse of psychostimulants, including amphetamines (AMPHs), is a major public health problem with profound psychiatric, medical, and psychosocial complications. The actions of these drugs at the dopamine transporter (DAT) play a critical role in their therapeutic efficacy as well as their liability for abuse and dependence. To date, however, the mechanisms that mediate these actions are not well-understood, and therapeutic interventions for AMPH abuse have been limited. Drug exposure can induce broad changes in gene expression that can contribute to neuroplasticity and effect long-lasting changes in neuronal function. Identifying genes and gene pathways perturbed by drug exposure is essential to our understanding of the molecular basis of drug addiction. In this study, we used Drosophila as a model to examine AMPH-induced transcriptional changes that are DAT-dependent, as those would be the most relevant to the stimulatory effects of the drug. Using this approach, we found genes involved in the control of mRNA translation to be significantly upregulated in response to AMPH in a DAT-dependent manner. To further prioritize genes for validation, we explored functional convergence between these genes and genes we identified in a genome-wide association study of AMPH sensitivity using the Drosophila Genetic Reference Panel. We validated a number of these genes by showing that they act specifically in dopamine neurons to mediate the behavioral effects of AMPH. Taken together, our data establish Drosophila as a powerful model that enables the integration of behavioral, genomic and transcriptomic data, followed by rapid gene validation, to investigate the molecular underpinnings of psychostimulant action.

Highlights

The use of prescribed and illicit amphetamines (AMPHs) has been growing steadily, with an estimated 50 million worldwide users in 2017 [1]
As we were primarily interested in the dopamine transporter (DAT)-dependent contribution to the transcriptional response to AMPH, we focused our further analysis on genes that no longer respond to AMPH in the absence of DAT, i.e., genes that are differentially expressed in the WT but not in the DAT mutant, when comparing the AMPH-treated groups to their respective vehicle controls
Given that DAT is the principal molecular target of AMPH [4, 5], we first analyzed the transcriptional response to the psychostimulant in fly brains in the presence or absence of DAT

Summary

Introduction

The use of prescribed and illicit amphetamines (AMPHs) has been growing steadily, with an estimated 50 million worldwide users in 2017 [1]. These drugs are widely abused, often leading to aggression, psychosis, cardiovascular damage, and a host of other medical and psychosocial complications [2, 3]. The actions of AMPHs lead to a dramatic increase of extracellular dopamine via non-exocytic efflux of dopamine through DATmediated reverse transport [4,5,6,7]. The mechanisms that mediate the transition from drug use to abuse are not fully understood, and therapeutic interventions for AMPH abuse have been limited and largely ineffective

Methods

Results

Conclusion