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Title: Role of spliceosome and microprocessor complex in the processing of Splice site Overlapping pri-miR-34b
Author: Mattioli, Chiara
Awarding Body: Open University
Current Institution: Open University
Date of Award: 2013
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Splicing and pri-miRNA cropping events occur co-transcriptionally, but the precise relationship between these two processes on pre-mRNA is not completely understood. I have studied the relationship between the spliceosome and the Microprocessor complex (MPC) activities in a novel class of miRNAs, named Splice site Overlapping (SO) miRNAs, whose hairpins overlap with splice sites. I focused on the evolutionarily conserved SO miR-34b, whose hairpin is in a non-coding transcript, juxtaposed to an acceptor splice site. In vivo, the transcript has a tissue specific, evolutionarily conserved pattern of alternative splicing, with variable amounts of the intron retention isoform, and different quantities of miR-34b are synthesised in the tissues. In minigene systems, I identified two indispensable elements for the recognition of the SO miR•34b 3' splice site: a branch point located in the hairpin and a downstream purine-rich enhancer (ESE). Splicing inhibition due to ESE or AG 3' splice site mutations increase miR-34b levels. Moreover, siRNA-mediated knock down of Drosha and DGCR8 improves splicing efficiency and abolishes miR-34b biosynthesis. Thus, the processing of 3' SO miR- 34b is regulated in an antagonistic manner by the MPC and the spliceosome due to competition between these two machineries on the nascent transcript. This novel competitive mechanism that discriminates between juxtaposed splice sites and pri-miRNA structures may be commonly used to regulate the relative amount of SO mi RNAs and mRNAs produced from a precursor RNA transcript.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available