Characterizing the effects of human cancer-associated histone H2A.Z missense mutations in Saccharomyces cerevisiae.
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Authors
Duhaime, Levi
Date
2024-09-27
Type
thesis
Language
eng
Keyword
Cancer , Histones , Genetics
Alternative Title
Abstract
The genomes of eukaryotes are organized into chromatin, a structure made up of DNA and histone proteins. At the most basic level, chromatin provides the instructions that allow eukaryotic organisms to function properly. A wide range of mutations on histone-encoding genes have been identified from whole-exome sequencing data of human cancer patients. These mutations disrupt the histone octamer, higher order chromatin structure, histone tail dynamics, DNA accessibility and transcription factor binding. Although most of these mutations remain to be studied, some, termed “oncohistones,” have been demonstrated to drive cancer development and are correlated with poor disease prognosis. The overarching goal of this work was to improve our understanding of the various mechanisms by which cancer-associated mutations affect genome function to provide insight to how they may contribute to cancer development and progression. Specifically, this project sought to advance our understanding of the effects of cancer-associated missense mutations to the histone H2A variant, H2A.Z, using budding yeast (Saccharomyces cerevisiae) as a model system. H2A.Z is highly conserved from budding yeast to humans and is implicated in a wide range of molecular processes, including transcriptional regulation, DNA damage repair, DNA replication, and cell cycle progression. Focusing on mutations that map to identical residues between budding yeast and humans, we have generated a library of 21 budding yeast strains, each of which expresses a different version of H2A.Z with introduction of a single cancer-associated missense mutation. These mutants were screened for effects on cellular growth, H2A.Z expression levels, H2A.Z-dependent gene expression, H2A.Z-H2B interaction, and histone post-translational modification levels. Here, we found that the htz1-R36H, htz1-T46S, htz1-L66F, htz1-L101W, htz1-L104R, and htz1-I109S mutants displayed growth defects upon exposure to various stressors previously shown to elicit growth defects in the htz1Δ background. Importantly, different mutations conferred sensitivity to a different subset of stressors and these sensitivities vary in their magnitude, indicating that different H2A.Z-dependent functions are being impacted by these mutations. These findings lay the groundwork for further investigation into which H2A.Z-dependent functions are being perturbed by these mutations in vivo.
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.