EPIGENETIC AND GENE EXPRESSION CHANGES MEDIATED BY HISTONE H3 METHYLATION IN ACUTE MYELOID LEUKEMIA
Open Access
- Author:
- Becker, Abigail Harris
- Graduate Program:
- Biomedical Sciences
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 26, 2018
- Committee Members:
- Sergei Grigoryev, Thesis Advisor/Co-Advisor
Kristin Eckert, Committee Member
Greg Yochum, Committee Member - Keywords:
- AML
Acute Myeloid Leukemia
Gene Expression
H3K9me2
Histone Methytransferase
G9a
G9a/EHMT2
Chromatin
ChIP-sequencing
Epegentics
LOCKs - Abstract:
- Histone modifications are the principal regulators of chromatin dynamics, mediating the extent of chromatin compaction which in turn alters DNA accessibility for gene regulation and repair. Large-scale chromatin remodeling, manifested by the progressive condensation of chromatin marked by the repressive histone modification H3K9me2, is essential to establish cell-specific gene expression patterns during lineage commitment and cellular differentiation. Dysregulation of this large-scale regulatory mechanism has been linked to cellular transformation and oncogenesis in cancer cell lines, diverse solid tumors and hematopoietic cancers. Acute myeloid leukemia (AML) is a highly malignant blood cancer and many of the recurrent gene fusions and driver mutations associated with AML are directly related to epigenetic regulation and chromatin higher order structure, suggesting broad genetic and epigenetic disruption in the pathogenesis of AML. We conducted Chromatin Immunoprecipitation followed by massively parallel sequencing (ChIP-seq) to analyze genome-wide H3K9me2 distribution in primary AML patient samples, CD34+ hematopoietic progenitors, and mature granulocytes, and identified distinct genomic regions marked by significant bidirectional changes of H3K9me2, including domains persistently altered in AML patient samples. In addition, we showed that targeting the histone methyltransferase G9a, which is responsible for the majority of euchromatic H3K9me2, with a pharmacologically active inhibitor, reverses some of the changes observed in AML cells. We performed ChIP-qPCR and transcriptional analysis of genes within the specific regions and in this thesis present evidence in support of the ChIP-seq analysis. We propose that the bidirectional changes in H3K9me2 domains (i.e. loss or gain of H3K9me2, rearrangement in domain size or location) results in coordinated activation or silencing of gene clusters, which significantly contributes to the development of AML.