Characterization of chromatin assembly in murine embryos
department or school: Science, Faculty of
department or school: Zoology, Department of
data provider: DSpace
degree campus: UBCV
creator: Jansen, Hailey Janice
issued: 2013-08-12T14:28:43Z
issued: 2013
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: During differentiation, changes in chromatin proteins lead to the establishment and maintenance of gene expression patterns. Histone H3 trimethylated at lysine 4 (H3K4me3) by the trithorax group (trxG) gene family Mixed lineage leukemia (MLL) is associated with active genes. H3K27me3 is trimethylated by the Polycomb group (PcG) Enhancer of Zeste (EZH2) at repressed genes. In Drosophila embryos, trxG and PcG proteins but not H3K4me3 or H3K27me3 are stable to DNA replication. In contrast, methylated histones are detected on nascent DNA in Drosophila and murine cell lines. Therefore some aspect of chromatin assembly or histone trimethylation must differ in different cells. My first aim was to determine if there is a change in the abundance of methylated histones at the replication fork in undifferentiated versus differentiated murine ES cells using two novel in vivo assays. Most undifferentiated ES cells lack early H3K4me3 and H3K27me3, but after 4 days of differentiation, most cells have early trimethylation of H3K4 and H3K27. I propose that the change in kinetics of histone methylation correlates with differentiation. To test this hypothesis, I carried out similar experiments on cells dissociated from day 9.5 (E9.5) and 14.5 (E14.5) murine embryos. In E9.5 cells there are two populations of cells, one that lacks methylated histones and the other contains methylated histones on nascent DNA. By E14.5 most cells exhibit H3K4me3 and H3K27me3 on nascent DNA. To determine if the presence of histone methyltransferases could account for the changes in histone methylation, I tested MLL1 and a subunit of the EZH2 complex, Su(z)12. Both are present continuously on nascent DNA, suggesting that their activity is regulated. Methylation and acetylation antagonize each other at the same residue. However I showed that the presence of acetylated H3K27 is not anticorrelated with H3K27me3 in most murine embryos cells. My results using inhibitors of the appropriate histone acetyltransfer…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/44768
note: CHARACTERIZATION OF CHROMATIN ASSEMBLY IN MURINE EMBRYOS by Hailey Janice Jansen B.Sc., The University of British Columbia, 2010 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Zoology) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) August 2013 ? Hailey Janice Jansen, 2013 ii Abstract During differentiation, changes in chromatin proteins lead to the establishment and maintenance of gene expression patterns. Histone H3 trimethylated at lysine 4 (H3K4me3) by the trithorax group (trxG) gene family Mixed lineage leukemia (MLL) is associated with active genes. H3K27me3 is trimethylated by the Polycomb group (PcG) Enhancer of Zeste (EZH2) at repressed genes. In Drosophila embryos, trxG and PcG proteins but not H3K4me3 or H3K27me3 are stable to DNA replication. In contrast, methylated histones are detected on nascent DNA in Drosophila and murine cell lines. Therefore some aspect of chromatin assembly or histone trimethylation must differ in different cells. My first aim was to determine if there is a change in the abundance of methylated histones at the replication fork in undifferentiated versus differentiated murine ES cells using two novel in vivo assays. Most undifferentiated ES cells lack early H3K4me3 and H3K27me3, but after 4 days of differentiation, most cells have early trimethylation of H3K4 and H3K27. I propose that the change in kinetics of histone methylation correlates with differentiation. To test this hypothesis, I carried out similar experiments on cells dissociated from day 9.5 (E9.5) and 14.5 (E14.5) murine embryos. In E9.5 cells there are two populations of cells, one that lacks methylated histones and the other contains methylated histones on nascent DNA. By E14.5 most cells exhibit H3K4me3 and H3K27me3 on nascent DNA. To determine if the presence of histone methyltransferases could account for the changes in histone methylation, I tested MLL1 and a s…
has type: Thesis/Dissertation
date issued: 2013-11
is shown at: 10.14288/1.0074032
language: eng
degree discipline: Zoology
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/44768