Date of Award

2017

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Graduate Group

Cell & Molecular Biology

First Advisor

Kathryn E. Wellen

Abstract

Cancer cells increase nutrient uptake to support viability and proliferation. The influx of nutrients alters intermediary metabolite levels, and compelling evidence shows that metabolite availability impacts cell functions through altering chromatin modifications and downstream gene expression. One such metabolic intermediate is acetyl-CoA, as the concentration of acetyl-CoA is positively correlated with histone and non-histone protein acetylation. Histone acetylation is emerging as a nutrient-sensitive process, conferring gene expression changes in response to nutrient availability. In this thesis, we examined the impact of acetyl-CoA metabolism on the epigenome. We established that histone acetylation is sensitive to acetyl-CoA concentrations, which are dynamically regulated by glucose availability. This dynamic increase in histone acetylation induces the expression of cancer-promoting genes. We hypothesized that oncogene activation could lead to increased histone acetylation through reprogrammed metabolism. In two mouse models of cancer, histone acetylation increased upon oncogene activation. Additionally, histone acetylation was positively correlated with phosphorylated AKT in human prostate tumors and glioma. To test whether AKT regulates histone acetylation through metabolic changes, we utilized glioblastoma cell lines expressing constitutively active AKT and found that AKT promotes histone acetylation in nutrient-limited conditions. Mechanistically, this occurs partly through AKT-mediated phosphorylation of ACLY at serine 455, increasing ACLY activity. These studies reveal a novel role for AKT-driven metabolic changes on global histone acetylation in cancer cells. To better understand how concentrations of acetyl-CoA could lead to differential gene expression, we investigated a subset of acetyl-CoA regulated genes. Under conditions in which intracellular acetyl-CoA is abundant, glioma cells upregulate expression of adhesion and migration genes, increase transwell migration, adhere better to ECM, and are efficient in wound healing. Genetic deletion or biochemical inhibition of acetyl-CoA generating enzyme, ACLY, abrogates nutrient-dependent adhesion and migration. We postulated that specificity for regulation of migration related gene expression would be achieved through regulation of transcription factors. Using computational analysis of our acetyl-CoA gene set, NFAT1 was predicted as the top transcription factor in promoting these genes. Through fluorescent single cell analyses, we find that acetyl-CoA triggers calcium oscillations that allow for NFAT1 nuclear localization. These findings suggest that that acetyl-CoA availability is differentially regulated in cancer cells and contributes to malignant phenotypes.

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Available to all on Monday, January 18, 2021

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