Regulation of the human RNA nucleotidyl transferase ZCCHC11

Thesis

Terminal uridylation of RNA 3ꞌ ends has recently been recognised as an important biological regulatory mechanism. The human terminal uridyl transferase ZCCHC11 was shown previously to uridylate and thereby regulate replication-dependent histone mRNAs and several miRNA precursors and mature miRNAs. Studies in cancer cell lines, mouse models and patient samples suggest that ZCCHC11 is a potential oncogene. However, very little is known about regulation of its expression and subcellular localisation. In this study, the regulation of the expression of ZCCHC11 was investigated, especially in relation to the roles played by the untranslated regions of its mRNA. The second aim of this study was to investigate the subcellular localisation of ZCCHC11, both under physiological conditions and under cellular stress. The results presented show that ZCCHC11 expression is regulated negatively through its 5ꞌ and 3ꞌUTRs. Upstream open reading frames in the 5ꞌUTR decrease its translation, while regulation through the 3ꞌUTR involves the combined activity of positive and negative factors. In this study it was shown that HuR positively regulates ZCCHC11 expression, whereas TTP contributes to its negative regulation. An homologous enzyme, ZCCHC6, negatively regulates ZCCHC11 expression. Regulation through the 3ꞌUTR of ZCCHC11 is particularly marked following S-phase arrest. ZCCHC11 expression increases under cellular stress and both UTRs take part in this regulation. Regulation under cellular stress also involves an alteration in sub-cellular localisation. ZCCHC11 is predominantly cytoplasmic in unstressed cells, but re-localises to p-bodies and stress granules under cellular stress. Mutating one of three zinc knuckle motifs within ZCCHC11 significantly decreased differential co-localisation with stress granule marker TIA-1 under oxidative stress. Taken together, the data presented provide insights into the post-transcriptional regulation of this post-transcriptional regulatory protein and its subcellular localisation, especially under cellular stress.

Authors: Akkaya, E

• Publication date: 2014
• DOI: 10.5287/ora-1ak4ygk6z
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: molecular pathology
• Subjects: Pathology