UC Merced

The ability to control when, and how much of the genetic code is being expressed is the underlying principle behind gene regulation. Control of gene production is able to influence a cell's phenotype by determining which structural components of the cell's observable traits (shape, growth, and behavior) are made. In multicellular organism’s different cell types are able to arise from the same genetic code due to a difference in the patterns of genes being expressed. Essentially anywhere in the process of gene expression from transcription, RNA processing, translation, and post-translational modifications of the protein is subject to regulation. As transcription is the first step in the process of gene expression, it is the first level of regulation for influencing the cell phenotype. The actions of transcription factors, histone modifiers, and other proteins work together to influence RNA polymerase's ability to complete the process of transcription. The actions of transcription factors are able to influence transcription by controlling the ability of RNA polymerase to be recruited to the start of a protein coding region and histone modifiers can rearrange the histones of the chromatin causing entire regions of a chromosome to become exposed or sequestered. These transcriptional regulators are able to work in a combinatorial fashion with one another to either activate and/or repress wide repertoires of transcriptional targets. Mapping out a network of interactions between these transcriptional regulators in gene expression programs allows researchers to understand how each protein is able to influence the phenotype of the cell, and how mutations to any of these transcriptional regulators are able to drive the cell into a diseased state. In the case of cancer, changes in the mechanisms of gene regulation brought on by mutations to these transcriptional regulators may drive the cell's hyper proliferative state. With the creation of next generation sequencing researchers are now better able to define where regulation is taking place in the genome, and how much it is able to influence gene expression. This gives researchers the ability to build these gene regulatory networks and evaluate their impact on gene expression. The subsequent chapters of this dissertation are a reflection of my published work investigating the contribution of oncogenic processes to gene regulatory networks in cancer through the study of hyperactivating somatic mutation of a histone modifier, changes in transcription factor response element specificity, epigenetic regulation of transcription factor signaling, and a transcription factor coactivation network.