Defense Date

2022

Document Type

Thesis

Degree Name

Master of Science

Department

Anatomy & Neurobiology

First Advisor

Peter Hamilton

Second Advisor

Andrew Ottens

Third Advisor

Jennifer Wolstenholme

Abstract

Anxiety and its related disorders have become increasingly prevalent as more awareness and acceptance of mental illnesses have come to fruition, especially in the light of the ongoing COVID-19 pandemic. Anxiety can affect anyone regardless of their age, sex, or social status and is currently the most commonly diagnosed mental illness worldwide (Bandelow & Michaelis, 2015). While there are several effective treatments available, the underlying brain mechanisms that cause anxiety are still largely unknown and further research continues to piece together the complex pathophysiology behind this disease. The use of laboratory animal models, such as mice, to induce and observe anxiety-like behaviors are an effective research method to determine specific molecular mechanisms that can influence anxiety. These studies may help to identify more effective treatments and improve the understanding of complex mental illnesses.

Our laboratory previously identified increased levels of protein expression of RPRD2 in the nucleus accumbens (NAc) of mice that were resilient to chronic social defeat stress (Hamilton et al., 2020). Known as regulation of nuclear pre-mRNA domain containing protein 2, this protein is largely unstudied and its mechanism and function remain incompletely understood. RPRD2 is a member of the RPRD family of proteins, which are known to downregulate transcription through interaction with the c-terminal domain of RNA polymerase II (Ali et al., 2019; Ramani et al., 2021). This thesis project began by exploring the specific effects of RPRD2 in the NAc of C57BL/6J mice, and while the initial hypothesis was that RPRD2 overexpression would make mice resilient to social defeat stress, it was subsequently found that there is a relationship between RPRD2 expression and anxiety-like behaviors.

To study this protein, a viral vector was created by inserting cDNA encoding RPRD2 into a destination vector using a LR clonase reaction. By packaging this plasmid within herpes simplex virus (HSV) and injecting mice with this viral RPRD2 in the NAc, it was observed that there was an increase in anxiety-like behavior such as avoiding the open arms of the elevated plus maze. These behaviors were noted regardless of whether these mice previously experienced chronic social defeat stress. However, the viral RPRD2 did not have any significant effects on the social behaviors of mice in the social interaction test, even when the mice were exposed to an accelerated chronic social defeat stress paradigm. This thesis proposed a potential mechanism for RPRD2 through binding to the c-terminal domain of RNA polymerase II. Once RPRD2 binds, it is thought to pause the progression of transcription to the elongation phase by dephosphorylating Serine 5. While more research must be performed to confirm this mechanism, the data from this thesis suggests that the injection of HSV-RPRD2 in the NAc increases anxiety-like behavior in mice. The results of this study will help to better understand one potential mechanism of anxiety as well as provide more insight to the in vivo function of the protein RPRD2.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

5-10-2022

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