- Title
- Characterising transcriptional perturbations arising from altered expression of schizophrenia-associated microRNA
- Creator
- Geaghan, Michael
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2019
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Schizophrenia is a severely debilitating psychiatric disorder which typically presents as a combination of symptoms including hallucinations, delusions, social withdrawal, and cognitive deficits. While much research to date has investigated various aspects of its pathophysiology and neurobiology, there are still many unknowns. In this thesis I have employed next-generation RNA sequencing technology to investigate the roles of microRNAs (miRNAs) in regulating the post-transcriptional expression profile of cells in schizophrenia. This was accomplished via three studies. In the first study, peripheral blood mononuclear cell (PBMC) samples from healthy controls and individuals with schizophrenia were analysed for changes in both miRNA and gene expression via RNA sequencing analysis. This data revealed an increase in immune-related gene expression among males with schizophrenia. These results were accompanied by reductions in the expression of various miRNAs predicted to target these genes, suggesting that these miRNAs – including miR-1271-5p, miR-221-5p, and let-7a-5p – may be important for regulating peripheral immune activity, and thus may be involved in regulating the abnormal immune activation that has been observed in schizophrenia. In the second study, a cell culture model of elevated DGCR8 expression was employed, using the neuron-like, differentiated SH-SY5Y human neuroblastoma cell line. The elevation of the miRNA biogenesis gene DGCR8 has been observed in brain tissue in schizophrenia and may represent a global change to miRNA biogenesis in neural tissue in the disorder. Analysis of miRNA and mRNA expression in this cell culture model via RNA sequencing revealed wide-sweeping changes to both expression profiles, and in particular demonstrated a reduction in expression of numerous genes involved in neuronal function, as well as genes known to be associated with schizophrenia. Furthermore, various cell cycle and apoptotic genes were upregulated, suggesting these processes could be involved in the disorder as well. Furthermore, the transcription factor YY1 was found to regulate DGCR8, and downregulation of this gene resulted in a similar miRNA expression profile to DGCR8 elevation, adding to preliminary evidence that this transcription factor may also be involved in schizophrenia neurobiology. Finally, the third study investigated the miRNA miR-1271-5p, again using the SH-SY5Y cell culture model. This miRNA was among the differentially expressed miRNAs elevated in the first study of PBMC RNA expression, and our lab has identified it as a potential player in regulating gene expression following neuronal depolarisation. This study involved both overexpressing and knocking down miR-1271-5p in vitro and employed both mRNA sequencing to investigate gene expression changes, as well as ribosome profiling to identify differentially translated genes. The results of this study suggest that this miRNA is involved in both regulating the cell cycle as well as aspects of neuronal morphology and locomotion, cellular functions that are vital to neurodevelopment and may be involved in development of schizophrenia. Together these results demonstrate a complex role for miRNAs in schizophrenia, both peripherally and in neuronal tissue. Understanding how schizophrenia-associated changes in miRNA expression affects the post-transcriptional gene expression profiles of cells helps to elucidate the mechanisms by which psychiatric diseases such as schizophrenia develop.
- Subject
- RNA; microRNA; miRNA; sequencing; RNA-seq; ribo-seq; gene expression; schizophrenia
- Identifier
- http://hdl.handle.net/1959.13/1406560
- Identifier
- uon:35646
- Rights
- Copyright 2019 Michael Geaghan, This thesis is currently under embargo and will be available from 30.07.2020
- Language
- eng
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