Epidermal growth factor receptor (EGFR) is a key modulator of a number of cellular processes such as cell fate, proliferation, migration, and apoptosis. The EGFR gene is commonly amplified in a number of cancers and EGFR has been implicated in Alzheimer’s disease, but its role in this context is uncertain. An internal ribosome entry site (IRES) within the EGFR 5’untranslated region (UTR) has been previously discovered which maintains EGFR expression under hypoxic conditions and has a high requirement for the eukaryotic initiation factor (eIF) 4A helicase. Requirement for eIF4A suggests that the structure of the IRES is important in its regulation. Identifying the structure of the IRES and the conditions in which the IRES is active could lead to the development of therapeutics targeting the IRES. The IRES was investigated using bicistronic luciferase vectors. The IRES was found to be active in serum starvation stress but this activation appeared to be cell type specific, suggesting the IRES may depend upon tissue specific trans-acting factors for function. The EGFR IRES appears to not be modular, drawing similarities to the L-myc IRES. Structural data was used to improve prediction models for the IRES, which identified a structural switch that may be regulated by trans-acting factors. Targeting the IRES with anti-sense oligonucleotides proved moderately successful in inhibiting cap-independent translation. To study translational control in an environment closer to those found in Alzheimer’s disease, a 3-dimensional model was developed. Although the model was not spherical and could not be used as intended, it may be useful as a model for studying stress gradients. The effects that EGF stimulation has on translational regulation is poorly understood, yet may be a significant mediator in disease. RNA-seq allows for the quantification of the entire transcriptome for a given condition, whilst polysome profiling fractions mRNA based on ribosomal association. Through polysome profiling, RNA-seq and ontological clustering, it was revealed that EGF increased the translational efficiency of genes associated with Alzheimer’s disease aetiology. Some of these genes were found to be directly connected to the production and oligomerisation of the amyloid beta protein.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:719700 |
| Date | January 2017 |
| Creators | Smalley, Daniel S. |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://eprints.nottingham.ac.uk/43474/ |
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