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Title: Selection of G-quadruplex specific proteins and their effects on gene expression
Author: Fernando, Himesh
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2008
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G-quadruplexes in the promoters of oncogenes have been identified as potential therapeutic targets for the regulation of gene transcription by quadruplex-binding molecules. KIT is a tyrosine kinase receptor found on the cell membrane, and forms part of the cell signalling pathway. Certain mutations within it result in constitutive activation leading to uncontrolled cell proliferation.  Elevated levels of KIT have been reported in most gastrointestinal cancer cases, hence making it a prime anti cancer target. c-kit, the gene encoding KIT, contains a G-rich sequence in its promoter. With the aid of circular dichroism, ultraviolet and 1H NMR spectroscopic techniques, I have demonstrated that this G-rich sequence can form a G-quadruplex. An important criterion for any potential therapeutic is to be able to act specifically on the target of interest with minimum off target effects. Therefore, I screened for single-chain antibodies and zinc fingers from phage display libraries, that can bind to the c-kit promoter quadruplex with high affinity and specificity. I have demonstrated that engineered proteins can not only distinguish quadruplex from duplex DNA, but also can discriminate between two intramolecular quadruplexes with similar sequences, a molecular recognition achievement that had not been demonstrated before. Finally, the selected quadruplex-binding proteins were introduced into cancer cells to investigate if they had an effect on the transcription of c-kit. Furthermore, using human whole genome microarrays, I have asked the question ‘do engineered quadruplex binding proteins cause differential expression of genes that contain putative quadruplex forming sequences?’
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available