DOI
https://doi.org/10.25772/8MNJ-GR82
Defense Date
2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Anatomy & Neurobiology
First Advisor
Peter J. Hamilton Ph.D.
Abstract
Administration of addictive drugs like cocaine or morphine initiates aberrant gene transcription within brain reward circuitry neurons, which contributes to the lasting behavioral maladaptations that define addiction. The drug-induced expression and function of key brain transcription factors (TFs) is one major mechanism through which these drugs are able to regulate transcription, and as a consequence, lasting damaging drug-related behaviors including compulsive drug use. The goal of this dissertation is to more fully understand the molecular mechanistic drug-specific actions of TFs within the rodent nucleus accumbens (NAc). The findings from these studies could serve as the basis to identify novel candidate targets for drug-specific pharmacotherapies to block or reverse substance use disorder (SUD) pathogenesis. In the work presented in this dissertation, we identified Zfp189, a gene encoding a KRAB containing zinc finger protein (KZFP) as a highly cocaine-responsive gene within the NAc. We pioneered modified CRISPR constructs to activate NAc Zfp189 expression, via the natural mechanisms that occur upon cocaine use, and in a NAc medium spiny neuron (MSN)-specific fashion (Teague, Picone et al., 2023). We discovered that Zfp189 expression alone potentiated both dopamine receptor D1 positive (Drd1+) and dopamine receptor D1 positive (Drd2+) MSN physiological function to that of a cocaine-like state and drove a worsening of cocaine-related behaviors, including cocaine self-administration in mice (Teague, Picone et al., 2023). Interestingly, these manipulations had no effect on morphine-related behaviors (Teague, Picone et al., 2023). Based on these results, we hypothesized that the NAc Zfp189 gene product (ZFP189) facilitates cocaine-induced brain adaptations specifically. Given the promising results of this study, we elected to perform further investigation of the cocaine-induced functions of ZFP189. To investigate the ZFP189 TF in the context of different specific drugs, we innovated novel synthetic biology approaches to re-program the function of ZFP189 TF. We created synthetic ZFP189 TFs by replacing the endogenous repressive KRAB moiety with the transcriptional activator VP64-p65-Rta (VPR) (ZFP189VPR). We delivered these synthetic 13 ZFP189 TFs to the NAc, and observed that these molecular manipulations altered behavioral and transcriptional adaptations to cocaine, but not morphine, saline, or palatable food. This body of work is highlighted in Chapter 3 and is currently in revision at Molecular Psychiatry. Given that one KZFP, ZFP189, could alter brain and behavioral responses to cocaine, we hypothesized that other members of the KZFP gene family could be involved in the brain mechanisms of drug-induced transcription and plasticity more broadly. To study the entire KZFP gene family, we elected to re-program the function all KZFPs by synthesizing a modified KRAB-interacting repressive protein co-factor TRIM28 which assembles with the conserved KRAB domain on KZFPs and activate genes that would otherwise be repressed by KZFPs (TRIM28VPR). While still preliminary, the results of virally delivering these TRIM28 variants to the NAc and testing the effect on drug-induced behavior and transcription indicates that dysregulating the function of the KZFPs alters behavioral and transcriptional responses to both cocaine and morphine. The central hypothesis of this dissertation NAc KZFP TF transcriptional function drives brain molecular adaptations to facilitate the pathogenesis of specific drug addictions. I justify and explore this central hypothesis in chapters below.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
10-16-2024
Included in
Behavioral Neurobiology Commons, Genetics Commons, Molecular and Cellular Neuroscience Commons, Molecular Genetics Commons