Biomedical Sciences ETDs

Publication Date

Fall 11-15-2017

Abstract

Substance use Disorders (SUDs) are characterized by chronic relapse after periods without symptoms. This has been hypothesized to stem from persistent alterations in corticolimbic circuit function and structure caused by drug-induced alterations in addiction-related gene (ARG) expression. Transcriptional and epigenetic regulation of ARGs and addiction-like behaviors have been well characterized but the role of post-transcriptional regulation is an understudied, yet promising field. RNA binding proteins (RBPs) are one post-transcriptional regulator of mRNA stability. HuD is a neuronal specific RBP that stabilizes mRNAs and is regulated by neuronal activity and cocaine. Another type of post-transcriptional regulator, microRNAs (miRNAs), are non-coding RNAs that target specific mRNAs for degradation or translational repression. Since both RBPs and miRNAs target the 3’UTR, this opens the possibility that these two classes of molecules could compete for access to a specific recognition site. We have found that miR-495 and HuD target a set of shared mRNAs via binding to the same GUUUGUUUG sequence. Many of these shared targets, including Bdnf and Camk2a mRNAs have been implicated in addiction and are considered ARGs. This led to my hypothesis that cocaine CPP differentially regulates HuD and miR-495 leading to a synergistic increase in ARG expression and addiction-like behaviors. We found that miR-495 was significantly decreased within the NAc while HuD protein and mRNA was significantly increased. CaMKIIα and BDNF mRNA and protein levels were increased in a similar fashion. Overexpression of HuD or miR-495 caused opposite effects on ARG expression and CPP behavior. Finally, to determine the in vivo capability of these two regulators to compete for behavior, we infused LV-miR-495 in HuDOE mice and trained them in CPP. We found that HuDOE + LV-miR-495 completely blocked the development of CPP compared to LV-GFP controls as well as diminishing expression of shared target mRNA and protein. This suggests that miR-495 and HuD have bidirectional roles in the regulation of CPP behavior. Further research on the role of post-transcriptional competition of shared targets on cellular dynamics and behavior may inform new pharmacological treatments that tip the balance of this post-transcriptional competition mechanism in the favor of remission.Substance use Disorders (SUDs) are characterized by chronic relapse after periods without symptoms. This has been hypothesized to stem from persistent alterations in corticolimbic circuit function and structure caused by drug-induced alterations in addiction-related gene (ARG) expression. Transcriptional and epigenetic regulation of ARGs and addiction-like behaviors have been well characterized but the role of post-transcriptional regulation is an understudied, yet promising field. RNA binding proteins (RBPs) are one post-transcriptional regulator of mRNA stability. HuD is a neuronal specific RBP that stabilizes mRNAs and is regulated by neuronal activity and cocaine. Another type of post-transcriptional regulator, microRNAs (miRNAs), are non-coding RNAs that target specific mRNAs for degradation or translational repression. Since both RBPs and miRNAs target the 3’UTR, this opens the possibility that these two classes of molecules could compete for access to a specific recognition site. We have found that miR-495 and HuD target a set of shared mRNAs via binding to the same GUUUGUUUG sequence. Many of these shared targets, including Bdnf and Camk2a mRNAs have been implicated in addiction and are considered ARGs. This led to my hypothesis that cocaine CPP differentially regulates HuD and miR-495 leading to a synergistic increase in ARG expression and addiction-like behaviors. We found that miR-495 was significantly decreased within the NAc while HuD protein and mRNA was significantly increased. CaMKIIα and BDNF mRNA and protein levels were increased in a similar fashion. Overexpression of HuD or miR-495 caused opposite effects on ARG expression and CPP behavior. Finally, to determine the in vivo capability of these two regulators to compete for behavior, we infused LV-miR-495 in HuDOE mice and trained them in CPP. We found that HuDOE + LV-miR-495 completely blocked the development of CPP compared to LV-GFP controls as well as diminishing expression of shared target mRNA and protein. This suggests that miR-495 and HuD have bidirectional roles in the regulation of CPP behavior. Further research on the role of post-transcriptional competition of shared targets on cellular dynamics and behavior may inform new pharmacological treatments that tip the balance of this post-transcriptional competition mechanism in the favor of remission.

Keywords

addiction, post-transcriptional regulation, camk2a, bdnf, nucleus accumbens

Document Type

Dissertation

Language

English

Degree Name

Biomedical Sciences

Level of Degree

Doctoral

Department Name

Biomedical Sciences Graduate Program

First Committee Member (Chair)

Nora Perrone-Bizzozero

Second Committee Member

Carlos Fernando Valenzuela

Third Committee Member

Jonathan Brigman

Fourth Committee Member

Andrea Allan

Fifth Committee Member

Derek Hamilton

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