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UBC Theses and Dissertations

High-throughput characterization of mutations in antioxidant responsive elements Chou, Alice


Understanding the binding specificity of transcription factors is an important step towards accurate computational prediction of regulatory sequences governing gene expression. Higher-throughput binding site characterization methods have long been available in the laboratory for the study of protein-DNA interactions in solution or upon a surface. In this thesis a new method is introduced for characterization of inducible regulatory sequences in living cells based on construction and analysis of promoter-reporter gene plasmids. Spiked oligonucleotides are used to generate libraries of regulatory sequences with subtle variations from a known regulatory element. Screening of the library in cell culture for the capacity of the mutated sequences to mediate expression provides a diverse collection of responsive and non-responsive sequences to aid in understanding the sequence requirement for an inducible transcription factor binding site. We apply the methodology to the study of antioxidant responsive elements, the target sites of the Nfe212 transcription factor. These target sequences commonly found in the promoters of detoxification genes modulate gene expression in response to a diverse array of chemicals. The variants serve as a primary screen for future targeted mutational analysis to further characterize context-specific sequence requirement in the ARE and/or interdependence between positions. Moreover, a transcription factor binding profile can be generated from functional ARE variants in the library screen. Such an ARE profile performs as well as standard profiles based on bona fide ARE sequences drawn from the scientific literature.

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