Functional Investigation of Histone Demethylation on Skin Stem Cell Proliferation and Differentiation

Ha, Sarah Cayee

Undergraduate Honors Thesis

Functional Investigation of Histone Demethylation on Skin Stem Cell Proliferation and Differentiation Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/9z903028c

Abstract

Histone demethylases are proteins that remove methyl groups on lysine or arginine residues on histone core proteins in the nucleus. Through the demethylation of histone proteins, these enzymes play an essential role in the regulation of many biological processes. Although histone demethylases have been associated with regulatory pathways, their functionality is still largely unknown. To investigate the functional role of histone demethylation in regulatory pathways such as proliferation and differentiation in skin stem cells, I employed a small molecule, Methylstat, to competitively inhibit histone demethylases. In my thesis study, I cultured isolated murine epidermal skin stem cells and human squamous cell carcinoma (SCC) cells to observe and analyze the dynamics of self-renewal and terminal differentiation imbued with different concentrations of Methylstat to induce a global inhibition of histone demethylases. By treating skin cells, or keratinocytes, with Methylstat, I demonstrated that histone demethylation inhibition caused a decrease in proliferation and induced premature cell death. Additionally, I showed that inhibition of histone demethylation affected the cell’s ability to survive during proliferation and impaired the differentiation progression throughout the differentiation process. I also found that individual expression of target genes, such as p63 and Loricrin, showed a clear decrease in expression levels in the presence of Methylstat with a distinct dosage dependent manner. Lastly, by treating different SCC lines, I saw that cancer cells were more sensitive to lower dosages of Methylstat than normal epithelial stem cells. Overall, these results show that histone demethylation plays a large role in the regulation of proliferation and differentiation in keratinocytes. These initial findings provide a novel insight into the functionality of histone demethylation in skin and raise the possibility that histone demethylation may play a role in epithelial cancers.

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