Defense Date

2011

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Human Genetics

First Advisor

Vladimir I Vladimirov

Second Advisor

Kenneth S Kendler

Abstract

MicroRNAs (miRNAs) are a family of small non-coding RNAs that regulate gene expression at both the mRNA and protein levels. MiRNAs have been shown to affect neuronal differentiation, synaptosomal complex localization and synapse plasticity, all functions thought to be disrupted in schizophrenia. We investigated the expression of 667 miRNAs (miRBase v.13) in the prefrontal cortex of individuals with schizophrenia (SZ, N = 35) and bipolar disorder (BP, N =35) using a real-time PCR-based Taqman Low Density Array (TLDA). After extensive QC steps, 441 miRNAs were included in the final analyses. At a FDR of 10%, 22 miRNAs were identified as differentially expressed between cases and controls, 7 dysregulated in SZ and 15 in BP. Using in silico target gene prediction programs, the 22miRNAs were found to target brain-specific genes contained within networks overrepresented for neurodevelopment, behavior, and SZ and BP disease development. Given that miRNAs can bind to their targets with imperfect complementarity, computational prediction of true miRNA:mRNA interactions has been difficult and therefore, functional validation of miRNA:mRNA interactions has been relatively sparse. Thus, it was the goal of this study to demonstrate biological functionality of miRNAs on their targets by evaluating transcriptional and translational levels of gene expression(real-time PCR, western blot) as well as determining miRNA target-site specificity (luciferase reporter gene assays). We investigated two miRNAs, miR-132 and miR-137, both of which have been shown to regulate neuronal function and development, and are believed to be associated with schizophrenia from two distinct avenues of research, miR-132 from expression studies and miR-137 from genetic studies. We demonstrated miR-132 down-regulates NTF3, DISC1, and GRIK5 at the transcript level and down-regulates GRIK5 at the protein level as well. Furthermore, we demonstrated miR-137 down-regulates TCF4, CACNA1C, CDK6, ANK3, and ZNF804A at the transcript level, and down-regulates TCF4, CACNA1C, and CDK6 at the protein level. Going further, we also demonstrated miR-137 binds specifically to target sites in the 3'-UTR of CACNA1C, TCF4, and CDK6, suggesting repression of these genes is directly mediated by miR-137. In total, this study provides strong evidence that miRNA dysregulation may contribute to schizophrenia pathogenesis.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

December 2012

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