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dc.contributor.advisorAdams, Ian
dc.contributor.advisorCaceres, Javier
dc.contributor.authorCordiner, Ross Andrew Alex
dc.date.accessioned2018-01-10T09:06:48Z
dc.date.available2018-01-10T09:06:48Z
dc.date.issued2016-11-29
dc.identifier.urihttp://hdl.handle.net/1842/25877
dc.description.abstractDGCR8 (DiGeorge critical region 8) protein constitutes part of the Microprocessor complex together with Drosha, and is involved in the nuclear phase of microRNA (miRNA) biogenesis. DGCR8 recognises the hairpin RNA substrates of precursor miRNAs through two double-stranded RNA (dsRNA) binding motifs and acts as a molecular anchor to direct Drosha cleavage at the base of the pri-miRNA hairpin. Recent characterisation of the RNA targets of the Microprocessor by HITSCLIP of DGCR8 protein revealed that this complex also binds and regulates the stability of several types of transcripts, including mRNAs, lncRNAs and retrotransposons. Of particular interest is the binding of DGCR8 to mature small nucleolar RNA (snoRNA) transcripts, since the stability of these transcripts is dependent on DGCR8, but independent of Drosha. This raises the interesting possibility that there could be alternative DGCR8 complex/es using different nucleases to process a variety of cellular RNAs. We performed mass spectrometry experiments and revealed that DGCR8 copurifies with subunits of the nucleolar exosome, which contains the exonuclease RRP6. We demonstrated DGCR8 and the exosome form a nucleolar complex, which degrade the mature snoRNAs tested within this study. Interestingly, we also show that DGCR8/exosome complex controls the stability of the human telomerase RNA component (hTR/TERC), and absence of DGCR8 creates a concomitant telomere phenotype. In order to identify the RNA targets of the DGCR8/Exosome complex on a global scale we performed iCLIP of endogenous and overexpressed RRP6 (wild-type and a catalytically inactive form). Thus, intersection of CLIP datasets from DGCR8 and RRP6 identified common substrates; accordingly snoRNAs were the most represented. In addition, we identified the cellular RNA targets of the RRP6 associated human exosome. The use of a catalytically inactive form of RRP6 stabilised important in vivo interactions that are highly dynamic and transient and also highlighted the role of RRP6-mediated trimming of 3’flanks of immature non-coding RNAs. We will present a global view of the RNA-binding capacity of the RRP6-associated exosome. In sum, we identified a novel function for DGCR8, acting as an adaptor to recruit the exosome to structured RNAs and induce their degradation. Moreover, we have identified DGCR8-depenedent substrates of the exosome and have demonstrated the requirement of RRP6 for 3’ processing of ncRNAs.en
dc.language.isoenen
dc.publisherThe University of Edinburghen
dc.relation.hasversionCellular functions of the microprocessor, Sara Macias, Ross A. Cordiner and Javier F. Caceres, Biochemical Society Transactions (2013) Volume 41, part 4, 838–843; doi:10.1042/BST20130011en
dc.subjectRNAen
dc.subjectmRNAen
dc.subjectsnoRNAen
dc.subjectexosomeen
dc.subjectmicroprocessoren
dc.subjectDGCR8en
dc.subjectCLIPen
dc.titleCellular functions of the microprocessor complexen
dc.typeThesis or Dissertationen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD Doctor of Philosophyen
dc.rights.embargodate2100-12-31en
dcterms.accessRightsRestricted Accessen


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